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Comparative study of agar gel immunodiffusion (AGID protocols for the diagnosis of equine infectious anemia in Brazil
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Fernanda Gonçalves Oliveira
Full Text Available To evaluate the Equine Infectious Anemia (EIA agar gel immunodiffusion (AGID protocols, two different kits commercially available in Brazil were used: an imported kit (kit A and a domestically produced kit (kit B. Kit A was submitted to the protocols recommended by the World Organization for Animal Health (OIE and the protocol recommended by the Ministério da Agricultura Pecuária e Abastecimento (MAPA. Kit B, the Brazilian kit, was submitted only to the MAPA-recommended protocol and was used as a reference in this study. A total of 345 equid serum samples, including field samples, serum sets from official laboratories and a weak positive serum control from National Veterinary Services Laboratories (NVSL, were used. Parameters such as the sensitivity of kit A in the two protocols, the detection limit of kits and the occurrence of nonspecific reactions or non-identity were evaluated. When Kit A was used for an AGID procedure performed according to the OIE-recommended protocol, the kit demonstrated good agreement with kit B and 99 % relative sensitivity. However, when kit A was processed according to the MAPA-recommended protocol, it failed to detect 1.16 % of weak positive samples and its relative sensitivity decreased to 96 %. The detection limit of kit A was lower than the detection limit of kit B for weak positive samples in both protocols. The occurrence of nonidentity reactions was higher with kit B than with kit A. The training of veterinarians to ensure the correct execution of the AGID test protocol should be intensified in Brazil.
Prevalence of Peste Des Petits Ruminants Virus (PPRV in Mardan, Hangu and Kohat District of Pakistan; Comparative Analysis of PPRV Suspected serum samples using Competitive ELISA (cELISA and Agar Gel Immunodiffusion (AGID
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Misbah Aslam
Full Text Available Peste des petits Ruminants (PPR is an acute, febrile, highly contagious and economically important viral disease of small ruminants. However PPR is more prevalent in sheep and goat. Competitive ELISA, Virus neutrilization test, and RT-PCR are the available techniques for diagnosis of PPR which give rapid detection where as Agar gel immunodiffusion and Counter immunoelectrophoresis were previously used for PPR detection. In this study two serological techniques were compared for PPR diagnosis. The main aim of this study was to evaluate the comparative sensitivity of both techniques for PPR detection. For this purpose one hundred and sixty PPR suspected serum samples collected from goats and sheep flocks (unvaccinated from three Districts of NWFP including Mardan, Hangu and Kohat were analyzed in National Veterinary Laboratories, Islamabad. Out of these 160 samples, fifty (50 were found positive for PPR antibodies with cELISA (Prevalence = 31.25%. The cELISA positive serum samples however gave negative results when tested with AGID although the control well was always positive. Thus it was concluded that cELISA technique is more sensitive and specific than AGID for PPR antibody detection. [Vet. World 2009; 2(3.000: 89-92
Prevalence of Peste Des Petits Ruminants Virus (PPRV) in Mardan, Hangu and Kohat District of Pakistan; Comparative Analysis of PPRV Suspected serum samples using Competitive ELISA (cELISA) and Agar Gel Immunodiffusion (AGID)
Misbah Aslam; Muhammad Abubakar; Rehana Anjum; Shamim Saleha; and Qurban Ali
Peste des petits Ruminants (PPR) is an acute, febrile, highly contagious and economically important viral disease of small ruminants. However PPR is more prevalent in sheep and goat. Competitive ELISA, Virus neutrilization test, and RT-PCR are the available techniques for diagnosis of PPR which give rapid detection where as Agar gel immunodiffusion and Counter immunoelectrophoresis were previously used for PPR detection. In this study two serological techniques were compared for PPR diagnosis...
Comparison of agar gel immunodiffusion test, enzyme-linked immunosorbent assay and PCR in diagnostics of enzootic bovine leukosis
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Malovrh Tadej
Full Text Available Bovine leukaemia virus (BLV is a retrovirus that induces a chronic infection in cattle. Once infected, cattle remain virus carriers for life and start to show an antibody response within a few weeks after infection. Eradication and control of the disease are based on early diagnostics and segregation of the carriers. The choice of a diagnostic method depends on the eradication programme, money resources and characteristics of the herd to be analysed. The agar gel immunodiffusion (AGID test has been the serological test of choice for routine diagnosis of serum samples. Nevertheless, in more recent years, the enzyme-linked immunosorbent assay (ELISA has replaced the AGID for large scale testing. For this purpose, commercially available BLV-ELISA kits were compared to the AGID and to the polymerase chain reaction (PCR method performed with two sets of primers, amplifying env region. The ELISA kit based on the p24 core protein was found to be less specific and served as a screening test. The ELISA kit based on the envelope glycoprotein (gpSI served as a verification test and gave a good correlation with the AGID test and PCR method. However, ELISA showed a higher sensitivity than AGID. The p24 based ELiSA was useful for screening a large number of samples, whereas gp51 based ELISA, AGID and PCR were more important for detecting the antibody response against the individual BLV-proteins and therefore for verification of the infection with BLV.
Enzyme-linked immunosorbent assay for the diagnosis of bovine leukosis: comparison with the agar gel immunodiffusion test approved by the Canadian Food Inspection Agency.
Simard, C; Richardson, S.; Dixon, P; Bélanger, C; Maxwell, P
Four commercially available bovine leukemia virus (BLV)-ELISA kits from Europe or the United States were compared to the agar gel immunodiffusion (AGID) test officially approved by the Canadian Food Inspection Agency (CFIA). A total of 1200 cattle serum samples were used. Three ELISA kits based on the envelope glycoprotein (gp51) gave an excellent correlation with the AGID test. The kappa values were 0.998, 0.984, and 0.986 for the ELISA kits #1, #2, and #3, respectively. The ELISA kit based ...
Simple procedure for preparation of bluetongue virus and epizootic hemorrhagic disease virus antigens for agar gel immunodiffusion.
Stott, J. L.; Osburn, B. I.
A simplified procedure was developed for preparing soluble antigen from two related orbiviruses, bluetongue and epizootic hemorrhagic disease viruses, for agar gel immunodiffusion. The antigens gave excellent results in both micro-agar gel diffusion (agar gel precipitin) and macro-agar gel diffusion (bluetongue immunodiffusion). Minor modification in the spatial arrangement of reference antisera, commonly utilized in the agar gel immunodiffusion tests, was employed to reduce the possible deve...
Avaliaçăo do teste de imunodifusăo mediante emprego do polissacarídeo "O" no diagnóstico da brucelose bovina / Evaluation of agar gel immunodiffusion test using O-chain-polysaccharide for diagnosis of bovine brucellosis
Scientific Electronic Library Online (English)
G.M., Costa; V.L.V., Abreu; F.C.F., Lobato; J.A., Silva; N.E., Martins.
Full Text Available Comparou-se o teste de imunodifusăo dupla em ágar gel (IDGA) pelo emprego do polissacarídeo "O" como antígeno com os testes de soroaglutinaçăo rápida, soroaglutinaçăo lenta, 2-mercaptoetanol, reaçăo de fixaçăo de complemento e antígeno tamponado acidificado no diagnóstico da brucelose, em bovinos in [...] fectados, năo infectados e recém-vacinados com a amostra B-19, visando ŕ diferenciaçăo de anticorpos vacinais daqueles associados ŕ infecçăo natural pela Brucella abortus. Nenhum dos testes realizados permitiu diferenciar precisamente anticorpos vacinais daqueles induzidos pela infecçăo brucélica e, nas condiçőes do presente trabalho, a utilizaçăo do IDGA com este objetivo poderia levar ŕ retençăo de animais infectados no rebanho. Abstract in english Agar gel immunodiffusion test (AGID) using the O-polysaccharide was compared with serologic tests used in brucellosis diagnosis in non-infected, infected and early vaccinated cattle with strain B-19, in order to differentiate vaccinal antibodies from those resulting of natural infection by Brucella [...] abortus. None of the techniques can differentiate with absolute reliability the vaccinal antibodies from antibodies associated with natural infection to Brucella abortus. Moreover, the use of AGID with this objective would cause maintenance of infected animals in the herd.
Comparison of an agar-gel immunodiffusion test with other serological methods for differentiating Brucella infected from vaccinated cattle.
McMahon, K. J.
An agar-gel immunodiffusion test was compared with other serological tests for detection of antibodies in the sera of 48 cattle vaccinated with Brucella abortus strain 19. Two hundred forty-two sera were tested over a 12 month period, and addition of positive reactions for each test resulted in totals of 170 for the card test, 74 for the standard tube-agglutination test, 71 for the 2-mercaptoethanol test, 64 for the dithiothreitol test and 22 for the agar-gel immunodiffusion test.
Improvements to the hemagglutination inhibition test for serological assessment of recombinant fowlpox-H5-avian-influenza vaccination in chickens and its use along with an agar gel immunodiffusion test for differentiating infected from noninfected vaccinated animals.
Swayne, David E; Avellaneda, Gloria; Mickle, Thomas R; Pritchard, Nikki; Cruz, Julio; Bublot, Michel
In general, avian influenza (AI) vaccines protect chickens from morbidity and mortality and reduce, but do not completely prevent, replication of wild AI viruses in the respiratory and intestinal tracts of vaccinated chickens. Therefore, surveillance programs based on serological testing must be developed to differentiate vaccinated flocks infected with wild strains of AI virus from noninfected vaccinated flocks in order to evaluate the success of vaccination in a control program and allow continuation of national and international commerce of poultry and poultry products. In this study, chickens were immunized with a commercial recombinant fowlpox virus vaccine containing an H5 hemagglutinin gene from A/turkey/Ireland/83 (H5N8) avian influenza (AI) virus (rFP-H5) and evaluated for correlation of immunological response by hemagglutination inhibition (HI) or agar gel immunodiffusion (AGID) tests and determination of protection following challenge with a high pathogenicity AI (HPAI) virus. In two different trials, chickens immunized with the rFP-H5 vaccine did not develop AGID antibodies because the vaccine lacks AI nucleoprotein and matrix genes, but 0%-100% had HI antibodies, depending on the AI virus strain used in the HI test, the HI antigen inactivation procedure, and whether the birds had been preimmunized against fowlpox virus. The most consistent and highest HI titers were observed when using A/turkey/Ireland/83 (H5N8) HPAI virus strain as the beta-propiolactone (BPL)-inactivated HI test antigen, which matched the hemagglutinin gene insert in the rFP-H5 vaccine. In addition, higher HI titers were observed if ether or a combination of ether and BPL-inactivated virus was used in place of the BPL-inactivated virus. The rFP-H5 vaccinated chickens survived HPAI challenge and antibodies were detected by both AGID and HI tests. In conclusion, we demonstrated that the rFP-H5 vaccine allowed easy serological differentiation of infected from noninfected birds in vaccinated populations of chickens when using standard AGID and HI tests. PMID:17992929
Use of enzyme immunoassay (ELISA) for monitoring effectiveness of rinderpest vaccination and comparative evaluation with Agar-Gel immunodiffusion test
International Nuclear Information System (INIS)
In line with other countries participating in the Pan African Rinderpest Campaign, Ghana wishes to monitor the success of a national rinderpest vaccination campaign. This involves the collection of sera from throughout the country in an epidemiologically acceptable manner and the use of a serological procedure that can test the sera for the presence of antibodies to the rinderpest virus. A comparison was carried out between an FAO/IAEA ELISA based system and an Agar-Gel Immunodiffusion test for the detection of antibodies to rinderpest virus in cattle. the ELISA was found to be faster than the Agar-Gel test, could handle larger number of samples in a short time and could detect lower levels than of immunoglobulins. Utilising the ELISA system to examine sera collected in two surveys of 3,500 and 1,818 samples from three regions (Greater Accra, Central and Volta regions) a very marked variable rate of seroconversion was demonstrated with levels lower than the desired 85%. It would appear that the primary cause of these lower than expected levels was related to an inadequate cold-chain. (author). 7 refs, 1 fig., 4 tabs
Comparision of Polymerase Chain Reaction and Agar Gel Immunodiffusion test in Detection of MarekAND#8217;s Disease Virus
A. Manicavasaka Dinakaran; G. Selvaraju; K. Jayalakshmi; T.R. Gopalakrishna Murthy; M. Geetha and S. Saravanan
A study was undertaken to identify Marek's disease virus (MDV) antigen by PCR and AGID and to test the significance of PCR and AGID by McNemar's test in detection of MDV antigen in outbreak in layer flocks. A total of twelve different MD outbreak flocks with varying flock size were selected in this study. Feather follicles were collected from 10 apparently healthy birds, 10 clinically affected birds and 10 dead birds separately in each outbreak. All the samples were subjec...
Imunodifusăo em gel de ágar com polissacarídeos de membrana de Brucella abortus 1119-3 no diagnóstico da brucelose bovina / Membrane polysaccharides of Brucella abortus 1119-3 in agar gel immunodifusion test in diagnosis of bovine brucellosis
Scientific Electronic Library Online (English)
J., Megid; M.G., Ribeiro; J.V.B., Agottani; G., Marcos Jr.
Full Text Available Comparou-se a prova de imunodifusăo em gel de ágar (IDGA), utilizando extrato polissacarídico (POLI O), obtido da amostra de B. abortus 1119-3, com os testes de soroaglutinaçăo rápida em placa, de soroaglutinaçăo lenta em tubos, de antígeno acidificado e de 2-mercaptoetanol para o diagnóstico da bru [...] celose bovina. O IDGA mostrou alta especificidade, porém sensibilidade inferior aos métodos convencionais. Abstract in english An agar gel immunodiffusion (AGID) test using the polysaccharide (POLIO O) extract obtained from Brucella abortus strain 1119-3, was compared to plate agglutination, tube agglutination, rose bengal plate and mercaptoethanol tests in the diagnosis of bovine brucellosis. The AGID assay with B. abortur [...] s polysaccharide antigens, presented a greater specificity but lower sensitivity for detecting brucellosis infected animals as compared to the conventional methods of antibody detection.
Evaluación de la eficacia de la prueba de inmunodifusión en gel agar para la detección de anticuerpos contra el virus de la leucosis enzootica bovina / Assessment of the Efficacy of the Agar Gel Immunodiffusion Test for the Detection of Antibodies Against the Enzootic Bovine Leukosis Virus
Scientific Electronic Library Online (English)
Zoraida, Nava; César, Obando; Magaly, Bracamonte; Aurico, Sousa; Mayra, Hidalgo.
Full Text Available contra el virus de la leucosis enzoótica bovina (VLEB), comparándola con el ensayo inmunoenzimático (ELISA). Se procesaron 360 muestras de suero bovino para ambas pruebas, siguiendo las indicaciones del fabricante. El grado de concordancia (GC), valores predictivos (VP) y razones de verosimilitud (R [...] V) fueron determinados y analizados. El GC entre ambas pruebas resultó ser del 86,4%, con un coeficiente Kappa (K) = 0,7. La IDGA detectó una significativa (P Abstract in english The efficacy of the agar gel immunodifusion test (AGID) for the detection of antibodies against the enzootic bovine leucosis virus (EBLV) was evaluated and compared with the ELISA test. A total of 360 bovine serum samples were tested for both tests, following the manufacturer instructions. The agree [...] ment degree (AD), predictive values (PV), and coefficient of probability (CP) were determined and analyzed. There was a good AD between both tests (86.4%; Kappa coefficient =0.7). The AGID test detected a significant (P
Diagnostic efficiency of Brucella soluble antigens in immunodiffusion tests and ability to differentiate Brucella abortus strain 19 vaccinated cattle / Eficięncia diagnóstica de antígenos solúveis de Brucella em testes de imunodifusăo e capacidade para diferenciar bovinos vacinados com Brucella abortus CEPA 19
Scientific Electronic Library Online (English)
José, DAFFNER; Pedro, ABALOS; Lautaro, PINOCHET; Mariela, SCORTTI; Santiago, URCELAY.
Full Text Available Foram comparados tręs antígenos solúveis: um hapteno nativo (NH) de B. melitensis 16M, um polissacarídeo (PS) obtido de B. abortus 1119-3 e outro polissacarídeo de cadeia O (O-Chain) originado também da última Brucella. Os testes de imunodifusăo radial (RID) e imunodifusăo em gel de ágar (AGID) fora [...] m confrontados com as tręs classes de soros bovinos: a) infectados naturalmente (n = 76), b) năo infectados (n = 130) e c) vacinados com B19 (n = 61) reagindo a testes sorológicos clássicos. Foram determinadas a sensibilidade (Se), a especificidade (Sp) e a capacidade para discriminar vacinados (ADV). A Se mais alta (84,3%) no teste RID foi demonstrada pelo antígeno NH, enquanto os tręs antígenos tiveram 100% de Sp. O antígeno O-Chain teve 100% de ADV nesse teste. O teste AGID com estes antígenos demonstrou 100% Sp e ADV, enquanto o antígeno PS mostrou uma melhor Se (86,6%). Finalmente, por sua qualidade de produçăo e eficięncia, os antígenos PS e NH representam uma alternativa segura e econômica para o diagnóstico suplementar da brucelose. Abstract in english Three soluble antigens were compared by radial immunodiffusion (RID) and agar gel immunodiffusion (AGID) tests: a native haptene (NH) from Brucella melitensis 16M, and a polysaccharide (PS) from B. abortus 1119-3, both obtained by non-hydrolytic methods, and the (O-Chain) polysaccharide extracted al [...] so from B. abortus 1119-3 but using an hydrolytic method. Three groups of bovine sera were tested: a) Naturally infected (n = 76); b) Non-infected (n = 130) and c) S-19 vaccinated (n = 61); the sensitivity (Se), the specificity (Sp) and the ability to differentiate vaccinated (ADV) were determined in each group a, b and c respectively. The highest Se in the RID test (84.3%) was achieved by NH; while the three antigens gave 100% Sp. The O-Chain showed 100% ADV in this test. In the AGID test PS antigen showed the best Se (86.6%), and all antigens showed 100% of Sp and ADV. Finally, for its production qualities and efficiency the antigens PS and NH represent a promising alternative for complementary diagnosis of brucellosis.
Rapid serum agglutination and agar gel immunodiffusion tests associated to clinical signs in rams experimentally infected with Brucella ovis / Teste de soro aglutinaçăo rápida e do teste de imunodifusăo em gel de ágar associados aos sinais clínicos em carneiros infectados experimentalmente com Brucella ovis
Scientific Electronic Library Online (English)
Cristiane Nakada, Nozaki; Nair Silva Cavalcanti de, Lira; Otávio, Augusto Filho; Hymerson Costa, Azevedo; Leandro, Rodello; Maurício Gaudério, Dasso; Sony Dimas, Bicudo; Joăo Marcelo Azevedo de Paula, Antunes; Jane, Megid.
Full Text Available O objetivo deste estudo foi avaliar o uso do teste de imunodifusăo em gel de ágar e o teste sorológico de aglutinaçăo rápida comparados aos sinais clínicos em carneiros infectados experimentalmente com Brucella ovis para o diagnóstico confirmatório da brucelose ovina. O perfil sorológico durante os [...] 12 meses pós-infecçăo mostrou flutuaçăo da resposta por anticorpos, que favorece a falha no diagnóstico. A avaliaçăo dos testes indicou que nenhum dos testes foi capaz de detectar a infecçăo durante todo o período de estudo. O estudo ressalta a importância de considerar os sinais clínicos para apoiar o diagnóstico confirmatório da infecçăo por Brucella ovis em carneiros. Abstract in english The purpose of this study was to evaluate the agar gel immunodiffusion and the rapid serum agglutination tests associated to clinical signs in rams experimentally infected with Brucella ovis. The serological profile during the 12 months of infection showed a large fluctuation of antibodies that favo [...] rs the failure in the diagnostic. The evaluation of tests after the experimental infection allowed to suggest that none of the tests were able to detect the infection throughout the period of study. The study reinforces the importance of considering the clinical signs to support the diagnosis of Brucella ovis infection in rams.
Rapid serum agglutination and agar gel immunodiffusion tests associated to clinical signs in rams experimentally infected with Brucella ovis Teste de soro aglutinaçăo rápida e do teste de imunodifusăo em gel de ágar associados aos sinais clínicos em carneiros infectados experimentalmente com Brucella ovis
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Cristiane Nakada Nozaki
Full Text Available The purpose of this study was to evaluate the agar gel immunodiffusion and the rapid serum agglutination tests associated to clinical signs in rams experimentally infected with Brucella ovis. The serological profile during the 12 months of infection showed a large fluctuation of antibodies that favors the failure in the diagnostic. The evaluation of tests after the experimental infection allowed to suggest that none of the tests were able to detect the infection throughout the period of study. The study reinforces the importance of considering the clinical signs to support the diagnosis of Brucella ovis infection in rams.O objetivo deste estudo foi avaliar o uso do teste de imunodifusăo em gel de ágar e o teste sorológico de aglutinaçăo rápida comparados aos sinais clínicos em carneiros infectados experimentalmente com Brucella ovis para o diagnóstico confirmatório da brucelose ovina. O perfil sorológico durante os 12 meses pós-infecçăo mostrou flutuaçăo da resposta por anticorpos, que favorece a falha no diagnóstico. A avaliaçăo dos testes indicou que nenhum dos testes foi capaz de detectar a infecçăo durante todo o período de estudo. O estudo ressalta a importância de considerar os sinais clínicos para apoiar o diagnóstico confirmatório da infecçăo por Brucella ovis em carneiros.
Estudio comparativo de un PCR anidado, ELISA y AGID en la detección del virus de la leucosis bovina en muestras de suero, sangre y leche / Comparative study of nested PCR, ELISA and AGID tests in the detection of bovine leukaemia virus infection in serum, blood and milk samples
Scientific Electronic Library Online (English)
R, Felmer; J, Zúńiga; M, Recabal.
Full Text Available Se evaluaron distintos métodos actualmente disponibles para el diagnóstico de la infección por el virus de la leucosis bovina (VLB). Los métodos empleados fueron AGID en suero, ELISA en muestras de suero y leche y PCR en linfocitos sanguíneos. De un total de 126 animales analizados, AGID identificó [...] un menor número de animales positivos (75) comparado con las pruebas PCR y ELISA aplicadas en muestras de suero y leche (100). Tres animales positivos a AGID fueron negativos a PCR y 28 de las 51 muestras negativas a AGID fueron positivas mediante PCR. La sensibilidad diagnóstica de PCR con respecto a AGID fue de 96%, mientras que la especificidad fue de 45% (kappa 0,45). Todos los animales positivos a AGID fueron también positivos a ELISA aplicado tanto en suero como en leche, mientras que 25 animales negativos a AGID fueron consignados como positivos a ELISA, en ambas muestras biológicas. De esta forma, la sensibilidad diagnóstica de ELISA respecto a AGID fue de un 100%, mientras que la especificidad fue de 51% (kappa 0,55). La menor sensibilidad observada de AGID no es debido a reacciones falso positivas de ELISA y PCR, sino más bien a una mayor sensibilidad de estas últimas, lo que sugiere reconsiderar la utilización del método AGID en aquellos países en que aún se utiliza como método oficial en los programas de erradicación de leucosis. Abstract in english Different methods available for the detection of bovine leukaemia virus (BLV) infection were evaluated. The methods evaluated were AGID in serum, ELISA in serum and milk, and PCR in blood lymphocytes. The AGID test identified a smaller number of positive animals (75/126) compared to PCR and ELISA te [...] sts (100/126). Three positive animals by AGID were negative by PCR and 28 of the 51 negative samples by AGID were positive by PCR. The sensitivity of PCR with respect to AGID was 96%, whereas the specificity was 45% (kappa 0.45). All positive animals by AGID were also positive by ELISA in serum and milk samples, whereas 25 negative animals by AGID were considered positive by the ELISA test, in both biological samples. Thus, sensitivity of the ELISA with respect to AGID was 100%, whereas specificity was 51% (kappa 0.55). The smaller sensitivity of AGID is not due to false positive reactions of ELISA and PCR tests, but rather to a greater sensitivity of these, which suggests a revision of AGID in those countries in which it is still used as the official method in the erradication programs of leukaemia.
[Immunodiffusion studies of the complete somatic antigens of Paramphistomum sp. and Fasciola hepatica].
Bratanov, V; Lilkova, N; Stoianova-Za?kova, L
Investigations were carried out through the agar gel immunodiffusion test of complete somatic antigens of Paramphistomum sp. and Fasciola hepatica, using the respective homologic and heterologic hyperimmune rabbit sera. Differences were established in the spectrum and number of the produced precipitation lines - 6 to Paramphistomum and 4 to Fasciola. With the identity test by the scheme in three after Zilber and Abelev (1962) no precipitation arcs were formed against the heterologic hyperimmune rabbit sera. This pointed the fact that there was no antigenic relation between the helminth species studies. PMID:6172897
21 CFR 866.4800 - Radial immunodiffusion plate.
... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents § 866.4800 Radial immunodiffusion plate. (a)...
Quantitative evaluation of pork adulteration in raw ground beef by radial immunodiffusion and enzyme-linked immunosorbent assay.
Martin, D R; Chan, J; Chiu, J Y
Quantitative estimates are important to establish whether pork adulteration in ground beef is accidental or intentional. A standard agar gel radial immunodiffusion (RID) test using forensic-grade antiserum to porcine albumin and an enzyme-linked immunosorbent assay (ELISA) using forensic-grade anti-porcine glycoprotein immunoglobulin were used to determine from 1 to 75% raw pork in raw ground beef. The RID test, which incorporated 1.5% anti-pork serum in 1% immunodiffusion agar, formed precipitin rings with pork albumin in agar wells. A linear standard curve was obtained by plotting the diffusion area against standard pork concentrations ranging from 0 to 80%. For the ELISA the endpoint optical density increased linearly versus log % pork between 0.0625% and 2% pork. In spiked samples, the RID test had a detection limit of 3 to 5%, a coefficient of variation (CV) of 22%, and a recovery of 105%. The ELISA had a detection limit of 1%, a CV of 18%, and a recovery of 114%. The mean recovery from the spiked samples by the ELISA and RID test was not significantly different (P > 0.05) from the known sample amounts. Quantitation by RID of 28 ground beef samples (27 of which were DTEK ELISA-positive for pork adulteration) revealed a wide range of pork content, with values as high as 48%. PMID:9874351
Evaluation of five commercially available immunodiffusion kits for detection of Coccidioides immitis and Histoplasma capsulatum antibodies.
Johnson, J. E.; Jeffery, B.; Huppert, M.
Five commercial test kits for the serodiagnosis of coccidioidomycosis and histoplasmosis based upon immunodiffusion were evaluated. The correlation of results with the test kits in the Clinical Laboratory varied from 71 to 100% for coccidioidomycosis. The correlation for coccidioidomycosis immunodiffusion testing varied from 57 to 83% when results from the test kits and the Mycology Research Laboratory were compared. Only 81% correlation was noted between the two laboratories when the same re...
Extraction of Equine Infectious Anemia Immunodiffusion Antigen with the Aid of the Chaotropic Agent, Thiocyanate
Hart, L. T.; Broussard, E. A.
Immunodiffusion antigen from spleens of horses infected with equine infectious anemia virus was prepared by methods employing freeze-thaw cycles and thiocyanate treatment. Thiocyanate (0.5 M) permitted the recovery of the greatest amount of antigen. Furthermore, it was most effective for recovery of immunodiffusion antigen from spleens which yielded unsatisfactory concentrations of antigen by the conventional freeze-thaw or water-extraction methods. The reactivity of the antigen did not appear to be affected by this chemical treatment. Images PMID:4348466
The single radial immunodiffusion assay highlights small antigenic differences among influenza virus hemagglutinins.
Rodda, S J; Gallichio, H A; Hampson, A W
The results of single radial immunodiffusion assays of influenza virus hemagglutinin were found to be greatly altered by small antigenic differences between test and reference strains. When such differences were present, the precise specificity of the antiserum used had a critical effect on the measured hemagglutinin antigen content obtained.
Studies on the major common precipitating antigen of capripoxvirus.
Kitching, R P; Hammond, J M; Black, D N
The proteins of sheep pox, goat pox, sheep and goat pox and lumpy skin disease (Neethling) viruses were labelled with [35S]methionine. The major structural polypeptides of these viruses co-migrated on polyacrylamide gels, demonstrating the very close biochemical relationship between them. Using the agar gel immunodiffusion (AGID) test with radiolabelled antigen preparations, a major common precipitating antigen was identified. This co-migrated on polyacrylamide gels with one of the major structural polypeptides [mol. wt. 67000 (67K)]. The use of [35S]methionine-labelled antigen preparations considerably improved the sensitivity of the AGID test as a diagnostic test for capripoxvirus antibody detection. PMID:3080547
Comparison of serological methods for the diagnostic of Caprine arthritis-encephalitis (CAE) in Rio de Janeiro, Brazil / Comparaçăo entre métodos sorológicos para o diagnóstico da Artrite-encefalite caprina (CAE) no Rio de Janeiro, Brasil
Scientific Electronic Library Online (English)
Madelayne, Cortez-Moreira; Walter M.R., Oelemann; Walter, Lilenbaum.
Full Text Available Soros de 562 caprinos foram submetidos ŕ pesquisa de Artrite-encefalite caprina através dos testes de imunodifusăo em gel de agarose (AGID) de teste imunoenzimático (ELISA). Das amostras testadas, 79 (14,1%) foram reativas em ambos os testes, mas 141 (25,1%) foram positivos apenas no ELISA. Assim, a [...] sensibilidade do ELISA em relaçăo ao AGID foi de 100% e a especificidade de 70,8%. Abstract in english Serum samples of 562 goats were tested for Caprine arthritis-encephalitis using agar gel immunodiffusion test (AGID) and enzyme linked immunosorbent assay (ELISA). Seventy-nine samples (14.1%) were reactive by both testes but 141 (25.1%) were reactive only by ELISA. ELISA, when compared to AGID, pre [...] sented 100% sensitivity and 70.8% specificity.
Bluetongue virus: comparative evaluation of enzyme-linked immunosorbent assay, immunodiffusion, and serum neutralization for detection of viral antibodies.
Poli, G.; Stott, J.; Liu, Y. S.; Manning, J. S.
Comparative studies on the detection of bovine serum immunoglobulin G antibodies to bluetongue virus with an enzyme-linked immunosorbent assay, an immunodiffusion method, and a serum neutralization assay demonstrated complete concordance between the enzyme-linked immunosorbent assay and the serum neutralization assay results. However, the immunodiffusion method failed to detect bluetongue virus antibody in a substantial number of sera found to possess bluetongue virus immunoglobulin G with th...
Ocorręncia da leucose enzoótica dos bovinos no Estado do Pará, Brasil / Occurrence of enzootic bovine leukosis in the State of Pará, Brazil
Scientific Electronic Library Online (English)
Éva, Molnár; László, Molnár; Hilma Tavares, Dias; Aluízio Otávio Almeida da, Silva; William Gomes, Vale.
Full Text Available A ocorręncia da infecçăo pelo Vírus da Leucose Enzoótica dos Bovinos (BLV) no Estado do Pará, foi estudada através do método de imunodifusăo em ágar-gel (AGID) e por um ensaio imunoenzimatico (ELISA) indireto, paralelamente. Os exames foram realizados com amostras de soros sanguíneos oriundos de bov [...] inos de diferentes raças sendo a maioria deles adultos. A prevalęncia observada foi de 49,8% (359/721) no ELISA e 26,0% (174/668) no AGID. Todos os 14 grupos dos animais estudados pelo ELISA indireto, mostraram a existęncia da infeçăo, enquanto que pelo método da AGID, dois grupos de animais foram negativos. Abstract in english The occurrence of the infection with Bovine Leukosis Virus (BLV) was examined in agar-gel immunodiffusion (AGID) test and with indirect enzyme-linked immunosorbent assay (ELISA), in the State of Pará, Brazil. The blood sera were collected from different breeds including Nelore, Piemontes, Simental, [...] Holstein Frisian, Indubrasil, Girolanda, Simbrasil and their cross-breedings. The majority of the animals were adults. The overall occurrence of infections was 49.8% (359/721) and 26.0% (174/668) for ELISA and AGID test, respectively. All animal groups examined showed infection in ELISA, however in the AGID test two groups were sera negative.
Improved methods for the fluorographic detection of weak ?-emitting radioisotopes in agarose and acrylamide gel electrophoresis media
International Nuclear Information System (INIS)
The use of acetic acid as a solvent for diphenyloxazole (PPO) in fluorographic procedures has been investigated. It is demonstrated to be superior to both dimethyl sulfoxide and methanol with respect to its suitability in both agarose and acrylamide gel electrophoresis systems. In addition, a method has been developed for impregnating fragile gels such as those used for immunodiffusion with PPO in preparation for fluorography. (Auth.)
Predictive value of serologic tests in the diagnosis and follow-up of patients with paracoccidioidomycosis Valor predictivo de las pruebas serologicas para el diagnostico y seguimiento de la paracoccidoidomycosis
Luz Elena Cano; Angela Restrepo
A serologic study was undertaken in a group of 43 patients with active paracoccidioidomycosis who were treated in the same form (ketoconazole), for identical periods of time (6 months), and folio wed-up for various periods posttherapy. The tests employed were agar gel immunodiffusion (AGID) and complement fixation (FC). Also studied were 50 sera from patients with proven histoplasmosis and pulmonary aspergilloma, 30 patients with culturaly proven tuberculosis as well as 92 specimens from heal...
Soroprevalence and risk factors associated to "Brucella canis" infection in dogs from Campina Grande, Paraíba Soroprevalęncia e fatores de risco associados ŕ infecçăo por Brucella canis em căes da
Robério Macedo Oliveira; Francisco Rafael Martins Soto; Fernanda Bernardi; Carolina de Sousa Américo Batista; Francisco de Assis Leandro Alves; Arau?jo Neto, Jose? O.; Inácio José Clementino; Clebert José Alves; Rodrigo Tavares Jordăo de Vasconcelos; Sérgio Santos Azevedo
The prevalence of brucellosis due to Brucella canis was investigated in dogs from Campina Grande, Paraíba, Northern region of Brazil, and the risk factors for seropositivity were also analyzed. For this purposes, 170 dogs' blood samples were collected during the rabies vaccination campaign, in September, 2003. The agar gel immunodiffusion test (AGID), by Brucella ovis lipopolysaccharides and proteins antigens, sample Reo 198, was used for serological diagnosis. The seroprevalence was 2.35%...
Detection of Brucella ovis in ovine from Paraíba State, in the Northeast region of Brazil
Clebert José Alves; Salomăo Moreira de Figueiredo; Sérgio Santos Azevedo; Inácio José Clementino; Lara Borges Keid; Sílvio Arruda Vasconcellos; Carolina de Sousa Américo Batista; Vivianne Cambuí Mesquita Rocha; Severino Silvano Higino
To determine the presence of Brucella ovis in ovine from Paraíba State, in the Northeast region of Brazil, 80 animals slaughtered in the public slaughterhouse of Patos city were used. Before slaughter, blood samples were collected by jugular venopuncture from each animal, and after slaughter, testicles, epidydimus and uterus were aseptically collected. For the serological diagnosis of B. ovis and B. abortus infections, the agar gel immunodiffusion (AGID) and Rose Bengal (RBT) tests were carr...
An investigation of equine infectious anaemia infection in the Central Anatolia region of Turkey
Sahna, K. C.; Simsek, A.; Bulut, O.; Kale, M.; Yavru, S.; Yapkic, O.
In this study, 162 horses, 80 donkeys and 51 mule serum samples were collected in Konya city. Additionally, 64 horse serum samples from Ankara and 49 samples from Kayseri city were included in the study. A total of 406 serum samples were examined by agar gel immunodiffusion (AGID) and enzyme-linked immunosorbent assay (ELISA) for antibody to equine infectious anaemia virus (EIAV) and no positive result was detected.
Electroimmunoassay, radioimmunoassay, and radial immunodiffusion assay evaluated for quantification of human apolipoprotein B
International Nuclear Information System (INIS)
We examined three immunoassay techniques for measuring apolipoprotein B in serum and major lipoprotein density fractions from normolipidemic and hyperlipoproteinemic persons, comparing values by electroimmunoassay, radioimmunoassay, and radial immunodiffusion assay with those determined gravimetrically. Electroimmunoassay is faster and simpler than radioimmunoassay, and equally precise (within- and between-assay coefficients of variation for both were 5 and 7%, respectively). All the immunoassays gave results that agreed with those by gravimetry for normolipidemic sera and the corresponding lipoprotein density fractions, but only electroimmunoassay results agreed with those by gravimetry for apolipoprotein B in lipoproteins of d < 1.019 g/ml isolated from hypertriglyceridemic patients. Concentrations of apolipoprotein B in plasma, determined by electroimmunoassay in a population of normal persons and patients with primary hyperlipoproteinemias, were: normals, 980 +- 200; type 1, 700 +- 160; type IIa, 2000 +- 260; type IIb, 2180 +- 300; type III, 1300 +- 340; type IV, 1470 +- 400; and type V, 1550 +- 390 mg/liter (mean +- SD). Lipoprotein density fractions from the hyperlipoproteinemic patients each had a characteristic distribution of free and associated forms of lipoprotein family B. The absolute concentration and distribution of apolipoprotein B between the free and associated forms of lipoprotein B may represent a useful indicator of the underlying biochemical defedicator of the underlying biochemical defect
Ocorręncia de anticorpos anti-Brucella abortus e anti-Brucella canis em căes rurais e urbanos do Município de Monte Negro, Rondônia, Brasil / Anti-Brucella abortus and anti-Brucella canis antibodies occurrence in rural and urban dogs from Monte Negro county, Rondônia, Brazil
Scientific Electronic Library Online (English)
Daniel Moura de, Aguiar; Guacyara Tenório, Cavalcante; Silvio Arruda, Vasconcellos; Jane, Megid; Vanessa Riesz, Salgado; Tais Fukuta, Cruz; Marcelo Bahia, Labruna; Adriano, Pinter; Jean Carlos Ramos da, Silva; Zenaide Maria, Moraes; Luís Marcelo Aranha, Camargo; Solange Maria, Gennari.
Full Text Available Foram avaliados 304 căes de ambiente rural e urbano do município de Monte Negro, Rondônia, através do Antígeno Acidificado Tamponado (AAT), Soroaglutinaçăo Lenta em Tubos (SAL) e 2-Mercaptoetanol (2-ME) para a pesquisa de anticorpos anti-Brucella abortus e da Imunodifusăo em gel de ágar (IDGA) e Imu [...] nodifusăo em gel de ágar com soro tratado com 2-Mercaptoetanol (IDGA-ME) para Brucella canis. Foram consideradas positivas as amostras reagentes nas provas confirmatórias do 2-ME e IDGA-ME. Verificaram-se 56 (18,4%) animais reagentes ao AAT e 12 (4,0%) reagentes a SAL. Apenas um căo (0,3%) foi considerado positivo, confirmado pela prova do 2-ME. Foram observadas 11 (3,6%) reaçőes á IDGA, porém năo houve confirmaçăo na prova do IDGA-ME. Ressalta-se a baixa ocorręncia de căes positivos ao 2-ME e a ausęncia de animais reagentes á IDGA-ME. Abstract in english Serum samples from 304 dogs living in urban or rural areas of Monte Negro County, Rondônia State, Brazil, were evaluated for Brucella abortus reactivity using the Rose-Bengal Test (RBT), Standard Tube agglutination Test (SAT), and Mercaptoethanol Test (MET), and for Brucella canis reactivity using t [...] he Immunodiffusion test (AGID) and Immunodiffusion test with 2-Mercaptoethanol (ME-AGID). Serum was considered positive if reacted in the MET or ME-AGID. Fifty-six (18.4%) dogs reacted by the RBT, and 12 (4.0%) by the SAT. One (0.3%) dog was positive by the MET. Eleven (3.6%) dogs reacted by the AGID, but with no confirmation by the ME-AGID. It the small occurrence of dogs reacting by the MET and the absence of reactivity by ME-AGID is emphasized.
Evaluation of western blotting for the diagnosis of enzootic bovine leukemia Avaliaçăo da técnica de western blot no diagnóstico da leucose enzoótica bovina
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E.T. Gonzalez
Full Text Available A western blotting (WB procedure has been developed for detecting antibodies to bovine leukosis virus (BLV in cattle sera. Two hundred and thirty three serum samples from naturally infected cattle with BLV virus and serial bleedings from experimentally BLV infected cows were used. An agar gel immunodiffusion test (AGID was used for comparing with the results obtained by WB. The AGID positive sera showed a different degree of reactivity by WB test against the two most important viral antigens (gp51 and p24, or against one of them. Other proteins (gp30, p15, p12 and p10 were not detected with any AGID positive sera, being observed occasionally three bands corresponding to the p24 protein. Using sera obtained by BLV experimental inoculation, the antibodies directed to p24 appeared early (between the 2nd and 4th week post inoculation and thereafter antibodies to gp51were detected in some animals. The analysis of field serum samples by AGID as compared to WB showed an agreement of 90.9%. Only 1.7% of sera were negative by AGID and positive by WB and 7.2% that were not conclusive by AGID and were defined by WB (4.2% as positive and 3.0% as negative.Um sistema de western blotting (WB foi desenvolvido para detecçăo de anticorpos contra o vírus da leucose em soros de bovinos. Foram utilizadas amostras de soros de 233 animais naturalmente infectados e soros de vacas experimentalmente infectadas. O teste de imunodifusăo em ágar (AGID foi usado para comparaçăo dos resultados. Graus diferentes de reatividade foram observados em soros positivos ao AGID, quando testados em WB frente a um ou aos dois antígenos mais importantes (gp51 e p24. Outras proteínas (gp30, p15, p12 e p10 năo foram detectadas por nenhum soro positivo ao AGID, sendo que tręs bandas correspondentes ŕ proteína p24 foram observadas ocasionalmente. Em soros obtidos por inoculaçăo experimental, anticorpos contra a proteína p24 foram detectados entre a segunda e a quarta semanas após a inoculaçăo e, em alguns animais, detectaram-se anticorpos anti-gp51 mais tardiamente. O estudo de soros de campo com AGID e WB mostrou concordância de 90,9% sendo que apenas 1,7% dos soros negativos pelo AGID foram positivos ao WB e 7,2% dos resultados năo conclusivos por AGID foram definidos por WB (4,2% como positivos e 3% como negativos.
Measurement of serum immunoglobulin concentration in killer whales and sea otters by radial immunodiffusion.
Taylor, Bernadette C; Brotheridge, Rory M; Jessup, David A; Stott, Jeffrey L
Killer whales and sea otters maintained in captivity are the subjects of routine health monitoring programs, and interest in immunologic studies in sea otters has been rising recently in response to potential impacts from infectious disease and environmental pollution on the threatened southern sea otter population. Development of species-specific reagents for immunologic studies in these two marine mammals is currently in its infancy. In this study, killer whale and sea otter immunoglobulin-specific polyclonal antibodies were generated, and used to develop tests for serum Ig concentration in the killer whale (Orcinus orca) and the southern (Enhydra lutris nereis) and northern sea otter (Enhydra lutris lutris). Killer whale serum IgG was purified using caprylic acid/ammonium sulfate precipitation. Sea otter plasma IgG was purified using protein-A-agarose. Polyclonal anti-Ig antisera were produced in rabbits, and specificity confirmed by immunoelectrophoresis. Radial immunodiffusion was used to measure Ig concentration in serum or plasma samples derived from 21 captive killer whales, 18 wild and 4 captive southern sea otters and 15 wild and 4 captive northern sea otters grouped by age. Mean killer whale serum Ig concentration (+/-95% confidence interval) ranged from 15.04 +/- 3.97 g/l for animals aged 0-5 years to 26.65 +/- 9.8 g/l for animals aged >10 years. Mean sea otter serum Ig concentration (+/-95% confidence interval) ranged from 28.39 +/- 11.00 g/l for southern sub-adults to 32.76 +/- 11.58 g/l for southern adults. No significant difference in serum Ig concentration was found between southern and northern sea otters. Serum Ig concentrations in two northern sea otter pups were low compared to those of adult sea otters. The two serum Ig quantitation assays produced were highly specific and reproducible and will be useful additions to the limited number of tests available for immune function in these marine mammal species. PMID:12383650
Comparaçăo de tręs testes sorológicos aplicados ao diagnóstico da infecçăo de caninos por Brucella canis / Comparison of three serological tests applied to diagnosis of the Brucella canis infection in dogs
Scientific Electronic Library Online (English)
Sérgio Santos de, Azevedo; Sílvio Arruda, Vasconcellos; Lara Borges, Keid; Lília Márcia Paulin da Silva, Grasso; Sônia Regina, Pinheiro; Roberta, Mascolli; Clebert José, Alves.
Full Text Available Foram comparados os testes de imunodifusăo em gel de ágar (IDGA), imunodifusăo em gel de ágar em soros tratados pelo 2-mercaptoetanol (IDGA-ME) e reaçăo de fixaçăo de complemento (CFT), aplicados ao diagnóstico da infecçăo de caninos por Brucella canis. O antígeno utilizado nas técnicas de IDGA e ID [...] GA-ME constituiu-se de lipopolissacarídeos e proteínas de Brucella ovis, amostra Reo 198, e na CFT, o antígeno empregado foi a Brucella ovis, amostra 63/290. Foram examinadas 80 amostras de soro sanguíneo de căes colhidas durante a campanha de vacinaçăo anti-rábica animal do Município de Santana de Parnaíba-SP, realizada em agosto de 1999. As provas sorológicas foram comparadas, duas a duas, pelo teste de Mc Nemar, e a concordância foi analisada pelo indicador Kappa. A concordância entre as técnicas de CFT e IDGA-ME foi regular (Kappa = 0,54), entre as técnicas de IDGA e CFT foi sofrível (Kappa = 0,36) e entre as provas de IDGA e IDGA-ME também foi sofrível (Kappa = 0,39). Abstract in english The agar gel immunodiffusion test (AGID), agar gel immunodiffusion test in sera treated by 2-mercaptoethanol (ME-AGID) and complement fixation test (CFT), applied to diagnosis of the canine brucellosis due to Brucella canis, were compared. For this purposes, 80 blood samples from dogs were collected [...] during the rabies vaccination campaign of Santana de Parnaíba municipality, State of Săo Paulo, in August 1999. The antigens used in the AGID and ME-AGID tests were lipopolysaccharides and proteins from Brucella ovis, strain Reo 198, and in the CFT, the antigen employed was Brucella ovis, strain 63/290. The serological tests were compared two by two by Mc Nemar test, and the agreement was analyzed by the Kappa indicator. The agreement between the CFT and ME-AGID was moderate (Kappa = 0.54), between the AGID and CFT was fair (Kappa = 0.36) and between the AGID and ME-AGID was fair (Kappa = 0.39).
Epidemiological studies on bluetongue virus infection in West Java, Indonesia
International Nuclear Information System (INIS)
In monitoring of sentinel cattle in West Java, seroconversions to orbiviruses occurred mostly at the end of the wet season. A low altitude site gave more reactors than did a high altitude site. Due to perceived inefficiencies of the agar gel immunodiffusion (AGID) test, a competitive ELISA (C-ELISA) was applied and the results compared with the AGID test results. C-ELISA detected antibodies at an earlier stage of infection than did the AGID test. Not all sera reacting in the AGID test reacted in C-ELISA, suggesting that the C-ELISA is more specific in detecting bluetongue virus (BTV) antibodies than the AGID. However, as the infection status of most field sera was not known, this could not be confirmed conclusively from the available data. A comparison of isolation methods indicated that isolates were obtained more frequently if samples were passaged in embryonated eggs before blind passage in A edes albopictus cells followed by passage in BHK-21 cells. Six BTV serotypes, 1,7,9,12,20,21 and 23 were identified and confirmed from apparently healthy sentinel cattle blood at low altitudes; BTV serotype 21 was also isolated from a pool of the Avaritia sub-genus of the Culicoides spp which contained 227 C. fulvus and 20 C. orientalis. (author). 17 refs, 2 figs, 1 tab
Specific determination of N-acetyl-?-D-hexosaminidase isozymes A and B by radioimmunoassay and radial immunodiffusion
International Nuclear Information System (INIS)
The two major isozymes of N-acetylhexosaminidase, namely hexosaminidase A and B were quantitatively determined in tissues and biological fluids of both normal individuals and Tay-Sachs patients. The determination was carried out by two sensitive immunoassays: radial immunodiffusion, using chromogenic substrate, and radioimmunoassay, which were developed in this study. For this purpose we used either a cross-reactive antiserum which reacts to a similar extent with both isozymes, or an antiserum reacting exclusively with hexosaminidase A (obtained by selective immunoadsorption). This enabled the quantitisation of the two isozymes separately, or in the presence of each other, in purified enzyme preparations or in tissue homogenates, affording a direct positive determination of hexosaminidase A. The results demonstrated that normal tissues contain the two isozymes in comparable amounts, whereas tissues of Tay-Sachs patients lack hexosaminidase A or any material which carries the A-specific antigenic determinants. The possible applications of these assays and their potential diagnosis are discussed. (orig.)
Aspergillus fumigatus fungus ball in hospitalized patients with chronic pulmonary disease: usefulness of double immunodiffusion test as a screening procedure
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M. F. Ferreira-da-Cruz
Full Text Available Double immunodiffusion (DID was used as a screening test for the diagnosis of aspergillosis. Three hundred and fifty patients were tested, all of them referred from a specialized chest disease hospital and without a definitive etiological diagnosis. When DID was positive addtional information such as clinical history and radiographic findings were requested and also surgical specimens were obtained whenever possible. Specific precipitin hamds for Aspergillus fumigatus antigen were found in 29 (8.3% of 350 patients sera. Nineteen (65.5% of the 29 patients with positive serology were recognized as having a fungus ball by X-rays signs in 17 or by pathological examination in 2 or by both in 8 patients. This two-year prospective study has shown that pulmonary aspergillos is a considerable problem among patiens admitted to a Chest Diseases Hospital, especially in those with pulmonary cavities or bronchiectasis.Trezentos e cinquenta pacientes sintomáticos respiratórios admitidos no Hospial Raphael de Paula Souza, sem diagnóstico etiológico definitivo, foram triados pela técnica de imunodifusăo dupla (IDD para aspergilose. Quando a IDD foi positiva, informaçőes adicionais como histórico e exames radiológicos foram requisitados e, quando possível, espécimes clínicos foram processados para exames micológicos e histopatológicos. Linhas de precipitaçăo específicas para o antígeno de A. fumigatus foram encontradas em 29(8,3% dos 350 soros de pacientes testados. Dezenove (65,5% dos 29 pacientes cm sorologia positiva foram reconhecidos como tendo boa fúngica pelos achados radiológicos em dois ou por ambos em oito pacientes. Este estudo prospectivo de dois anos mostrou que aspergilose pulmonar é um problema considerável entre pacientes admitidos em um hospital para sintomáticos respiratórios, especialmente aqueles com cavidades pulmonares ou bronquiectasias.
Aspergillus fumigatus fungus ball in hospitalized patients with chronic pulmonary disease: usefulness of double immunodiffusion test as a screening procedure
Scientific Electronic Library Online (English)
M. F., Ferreira-da-Cruz; B., Wanke; C., Pirmez; B., Galvăo-Castro.
Full Text Available Trezentos e cinquenta pacientes sintomáticos respiratórios admitidos no Hospial Raphael de Paula Souza, sem diagnóstico etiológico definitivo, foram triados pela técnica de imunodifusăo dupla (IDD) para aspergilose. Quando a IDD foi positiva, informaçőes adicionais como histórico e exames radiológic [...] os foram requisitados e, quando possível, espécimes clínicos foram processados para exames micológicos e histopatológicos. Linhas de precipitaçăo específicas para o antígeno de A. fumigatus foram encontradas em 29(8,3%) dos 350 soros de pacientes testados. Dezenove (65,5% dos 29 pacientes cm sorologia positiva foram reconhecidos como tendo boa fúngica pelos achados radiológicos em dois ou por ambos em oito pacientes. Este estudo prospectivo de dois anos mostrou que aspergilose pulmonar é um problema considerável entre pacientes admitidos em um hospital para sintomáticos respiratórios, especialmente aqueles com cavidades pulmonares ou bronquiectasias. Abstract in english Double immunodiffusion (DID) was used as a screening test for the diagnosis of aspergillosis. Three hundred and fifty patients were tested, all of them referred from a specialized chest disease hospital and without a definitive etiological diagnosis. When DID was positive addtional information such [...] as clinical history and radiographic findings were requested and also surgical specimens were obtained whenever possible. Specific precipitin hamds for Aspergillus fumigatus antigen were found in 29 (8.3%) of 350 patients sera. Nineteen (65.5%) of the 29 patients with positive serology were recognized as having a fungus ball by X-rays signs in 17 or by pathological examination in 2 or by both in 8 patients. This two-year prospective study has shown that pulmonary aspergillos is a considerable problem among patiens admitted to a Chest Diseases Hospital, especially in those with pulmonary cavities or bronchiectasis.
Technical note: Comparison of radial immunodiffusion and ELISA for quantification of bovine immunoglobulin G in colostrum and plasma.
Gelsinger, S L; Smith, A M; Jones, C M; Heinrichs, A J
Historically, radial immunodiffusion (RID) has been the only method that directly measures IgG; however, recent studies have reported IgG concentrations in colostrum, milk, and plasma as measured using an ELISA. To our knowledge no comparison between RID and ELISA methods has been made for bovine colostrum or plasma. The objective of this study was to compare IgG concentrations measured by both methods in samples of bovine colostrum before and after heat treatment and bovine plasma. Concentration of IgG was quantified using a commercially available RID kit and a modified ELISA. Samples of bovine colostrum and plasma were collected from individual animals and colostrum was tested before and after heat treatment at 60°C for 30min. All samples were tested using both methods. Pearson correlation coefficients were determined for RID and ELISA values from unheated colostrum, heat-treated colostrum, and plasma samples. Mixed models were used to determine the effect of assay on IgG measurement in colostrum and plasma and effect of heat treatment on IgG concentration in colostrum. A weak correlation was found between ELISA and RID results in plasma and unheated colostrum. Concentration of IgG was significantly lower in all sample types when measured by ELISA compared to RID. Thus, direct comparison of ELISA and RID results is not recommended. Colostrum IgG concentration significantly decreased after heat treatment as measured by ELISA, but means were not different when measured by RID. Correlation plots between colostrum values measured before and after heat treatment indicated changes in the colostrum protein matrix due to heat affected RID and ELISA assays differently. This investigation compared RID and ELISA results, but no conclusions could be drawn as to the accuracy of either assay. PMID:25841961
The efficiency of Peste des petits ruminants virus (PPRV) vaccines available in Pakistan was evaluated on the basis of the humoral immune response measured by haemagglutination inhibition (HI) and agar gel immunodiffusion (AGID) tests in sheep (n=60) and goats (n=60). The effect of storage temperature on HA activity of vaccine virus was measured by holding the vaccine at -20, 4, 27 and 40°C for 24 hours. The titer of freshly prepared vaccine was 1:16 and remained unchanged for 24 hours in ...
Seroprevalence of infectious bursal disease virus in local chickens in Udu Local Government Area of Delta State, South East Nigeria.
Abraham-Oyiguh, J; Adewumi, M O; Onoja, A B; Suleiman, I; Sulaiman, L K; Ahmed, S J; Jagboro, S T
Infectious Bursal Disease Virus (IBDV) poses a great global threat to the poultry industry. Knowledge of the occurrence of the disease is important in the design and implementation of a control program, therefore this study determines the seroprevalence of IBDV in local chickens in Udu Local Government Area of Delta State. 250 chickens were bled by exsanguination and sera obtained were screened using Agar Gel Immunodiffusion (AGID) test. The seropositivity was 51.6%, which is indicates endemicity of the disease. Biosecurity and good sanitary measures are recommended. Molecular characterization of the strains should be carried out for inclusion in generic vaccines. PMID:25331185
Mora, Thierry; Boudaoud, Arezki
The patterns arising from the differential swelling of gels are investigated experimentally and theoretically as a model for the differential growth of living tissues. Two geometries are considered: a thin strip of soft gel clamped to a stiff gel, and a thin corona of soft gel clamped to a disk of stiff gel. When the structure is immersed in water, the soft gel swells and bends out of plane leading to a wavy periodic pattern which wavelength is measured. The linear stability...
Detection of Brucella ovis in ovine from Paraíba State, in the Northeast region of Brazil
Scientific Electronic Library Online (English)
Clebert José, Alves; Salomăo Moreira de, Figueiredo; Sérgio Santos de, Azevedo; Inácio José, Clementino; Lara Borges, Keid; Sílvio Arruda, Vasconcellos; Carolina de Sousa Américo, Batista; Vivianne Cambuí Mesquita, Rocha; Severino Silvano, Higino.
Full Text Available To determine the presence of Brucella ovis in ovine from Paraíba State, in the Northeast region of Brazil, 80 animals slaughtered in the public slaughterhouse of Patos city were used. Before slaughter, blood samples were collected by jugular venopuncture from each animal, and after slaughter, testic [...] les, epidydimus and uterus were aseptically collected. For the serological diagnosis of B. ovis and B. abortus infections, the agar gel immunodiffusion (AGID) and Rose Bengal (RBT) tests were carried out, respectively. In addition, microbiological culture and polymerase chain reaction (PCR) were performed on testicle, epidydimus and uterus samples. Six animals (7.5%) tested positive for the presence of B. ovis antibodies and all animals tested negative for the presence of B. abortus antibodies. One AGID-positive animal tested positive at uterine swab culture. PCR was able to amplify DNA of Brucella spp. from the pool of testicle, epidydimus and uterus samples from AGID-positive animals. This is the first report of isolation and detection of B. ovis DNA by PCR in ovine from the Northeast region of Brazil.
Blastomycosis in nondomestic felids.
Storms, Timothy N; Clyde, Victoria L; Munson, Linda; Ramsay, Edward C
Blastomycosis was diagnosed in six nondomestic felids from eastern Tennessee, including two Asian lions (Panthera leo persicus), one African lion (Panthera leo), one Siberian tiger (Panthera tigris), one cheetah (Acinonyx jubatus), and one snow leopard (Panthera uncia). Clinical signs included lethargy, anorexia, weight loss, dyspnea, sneezing. ataxia, and paresis. Variable nonspecific changes included leukocytosis, monocytosis, moderate left shift of neutrophils, moderate hypercalcemia, hyperproteinemia, and hyperglobulinemia. Thoracic radiographs revealed interstitial and alveolar changes, consolidation or collapse of a lung lobe, bullae formation, and a pulmonary mass. Agar gel immunodiffusion (AGID) serology for Blastomyces dermatitidis was performed in five felids and was positive in three. The tiger had cerebral blastomycosis and was positive for AGID serologic tests of both cerebrospinal fluid and serum. One percutaneous lung aspirate in the snow leopard and one bronchial aspirate in an Asian lion demonstrated B. dermatitidis organisms. whereas tracheal wash samples and a nasal discharge were nondiagnostic in others. Treatment with itraconazole was attempted in four cats. The tiger improved before euthanasia, whereas the others did not survive beyond initial treatments. In four felids, B. dermatitidis was found in the lungs and tracheobronchial lymph nodes associated with a florid pyogranulomatous reaction; the tiger had a pyogranulomatous encephalomyelitis, and the cheetah had a single pulmonary granuloma. Thoracic radiography, cytologic examination of lung lesion aspirates, and B. dermatitidis AGID serology should be performed on clinically ill zoo felids in endemic areas to rule out blastomycosis. PMID:14582783
Detection of rubella-specific serum IgG and IgA and nasopharyngeal IgA responses using a radioactive single radial immunodiffusion technique
International Nuclear Information System (INIS)
A radioactive, single radial immunodiffusion technique (RSRID) employing 125I-labelled antiglobulins, was developed to determine rubella-specific serum IgG and IgA and nasopharyngeal IgA antibody responses following both naturally acquired rubella and vaccination with four attenuated vaccines. Rubella-specific IgG antibodies developed in parallel with haemagglutination inhibiting (HAI) antibodies and both persisted for at least a year in all cases of naturally acquired and vaccine induced infection. However, the RSRID test detected rises in titre in all of five volunteers challenged intranasally with RA27/3, whereas only one volunteer showed a rise by HAI. Serum IgA antibodies generally persisted for at least a year following naturally acquired infection but rubella vaccines induced variable responses. Thus, following administration of RA27/3 and To-336 vaccines, rubella-specific IgA usually persisted for a year, whereas Cendehill vaccine failed to induce a detectable response. Rubella-specific nasopharyngeal IgA was detected in all five patients following naturally acquired infection and was still present in the only two patients tested a year after infection. These antibodies were detected in fourteen of twenty-three vaccinees at 3 weeks, but persisted for a year in only two vaccinees, both of whom were given RA27/3 intranasally. (author)
The feasibility of using antigens prepared with rough Brucella strains for diagnosis of canine brucellosis Utilidad de los antígenos preparados con cepas rugosas de Brucella en el diagnóstico de brucelosis canina
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G. I. Escobar
Full Text Available Clinical diagnosis of canine brucellosis is not sensitive enough and a negative blood culture cannot rule out the disease. Indirect methods of serological testing such as agar gel immunodiffusion (AGID, rapid slide agglutination test (RSAT and indirect enzyme linked immunoassay (IELISA are preferred for routine diagnosis. Since Brucella canis shares antigenic components with the Brucella ovis and Brucella abortus RB51 strain, it would seem that either strain could be used as antigen. We present data on AGID and IELISA tests using the B. ovis antigen, RSAT and IELISA using the B. canis antigen and IELISA using the B. abortus RB51 antigen. The cut-off values were adjusted by the ROC analysis; the IELISA-B. ovis cut-off value was 23 (%P and the IELISA-B. abortus RB51, 24 (%P, with 100% sensitivity and 98.8% specificity. RSAT detected 100% of positive cases, while AGID was less sensitive. The sera from dogs treated with antibiotic showed that %P correlated well with the clinical course. Sera from dogs presumptively infected with B. suis were negative in all tests performed with the rough Brucella strains. RSAT is a very sensitive screening test and IELISA-B. canis, B. ovis and B. abortus RB51 could be used as confirmatory tests, since they show good specificity and sensitivity.Las técnicas más usadas en el diagnóstico de brucelosis canina son la inmunodifusión en gel de agar (AGID, la microaglutinación en portaobjetos (RSAT y el ELISA indirecto ya que el diagnóstico clínico es poco sensible y el bacteriológico no excluye la enfermedad. Como Brucella canis comparte componentes antigénicos con Brucella ovis y Brucella abortus RB51, estas cepas podrían ser usadas indistintamente como antígenos. En este trabajo presentamos datos sobre las pruebas de AGID e IELISA con antígeno B. ovis, RSAT e IELISA con antígeno B. canis e IELISA con antígeno B. abortus RB51. Los puntos de corte ajustados con la curva ROC fueron (%P 23 para IELISA-B. ovis y (%P 24 para IELISA-RB51 con 100% de sensibilidad y 98,8% de especificidad. RSAT detectó el 100% de los casos positivos, pero AGID fue menos sensible. Los sueros de los perros tratados con antibióticos tuvieron un %P que correlacionó con la evolución clínica. Los perros presumiblemente infectados con B. suis fueron negativos a todos los ensayos realizados con antígenos de cepas de Brucella rugosas. RSAT es muy sensible como prueba tamiz y los IELISA con antígenos de B. canis, B. ovis y B. abortus RB51 podrían ser usados como confirmatorios ya que han demostrado alta sensibilidad y especificidad.
The feasibility of using antigens prepared with rough Brucella strains for diagnosis of canine brucellosis / Utilidad de los antígenos preparados con cepas rugosas de Brucella en el diagnóstico de brucelosis canina
Scientific Electronic Library Online (English)
G. I., Escobar; E. J., Boeri; S. M., Ayala; N. E., Lucero.
Full Text Available Las técnicas más usadas en el diagnóstico de brucelosis canina son la inmunodifusión en gel de agar (AGID), la microaglutinación en portaobjetos (RSAT) y el ELISA indirecto ya que el diagnóstico clínico es poco sensible y el bacteriológico no excluye la enfermedad. Como Brucella canis comparte compo [...] nentes antigénicos con Brucella ovis y Brucella abortus RB51, estas cepas podrían ser usadas indistintamente como antígenos. En este trabajo presentamos datos sobre las pruebas de AGID e IELISA con antígeno B. ovis, RSAT e IELISA con antígeno B. canis e IELISA con antígeno B. abortus RB51. Los puntos de corte ajustados con la curva ROC fueron (%P) 23 para IELISA-B. ovis y (%P) 24 para IELISA-RB51 con 100% de sensibilidad y 98,8% de especificidad. RSAT detectó el 100% de los casos positivos, pero AGID fue menos sensible. Los sueros de los perros tratados con antibióticos tuvieron un %P que correlacionó con la evolución clínica. Los perros presumiblemente infectados con B. suis fueron negativos a todos los ensayos realizados con antígenos de cepas de Brucella rugosas. RSAT es muy sensible como prueba tamiz y los IELISA con antígenos de B. canis, B. ovis y B. abortus RB51 podrían ser usados como confirmatorios ya que han demostrado alta sensibilidad y especificidad. Abstract in english Clinical diagnosis of canine brucellosis is not sensitive enough and a negative blood culture cannot rule out the disease. Indirect methods of serological testing such as agar gel immunodiffusion (AGID), rapid slide agglutination test (RSAT) and indirect enzyme linked immunoassay (IELISA) are prefer [...] red for routine diagnosis. Since Brucella canis shares antigenic components with the Brucella ovis and Brucella abortus RB51 strain, it would seem that either strain could be used as antigen. We present data on AGID and IELISA tests using the B. ovis antigen, RSAT and IELISA using the B. canis antigen and IELISA using the B. abortus RB51 antigen. The cut-off values were adjusted by the ROC analysis; the IELISA-B. ovis cut-off value was 23 (%P) and the IELISA-B. abortus RB51, 24 (%P), with 100% sensitivity and 98.8% specificity. RSAT detected 100% of positive cases, while AGID was less sensitive. The sera from dogs treated with antibiotic showed that %P correlated well with the clinical course. Sera from dogs presumptively infected with B. suis were negative in all tests performed with the rough Brucella strains. RSAT is a very sensitive screening test and IELISA-B. canis, B. ovis and B. abortus RB51 could be used as confirmatory tests, since they show good specificity and sensitivity.
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Adriana Hellmeister de Campos Nogueira
Full Text Available
Mukherjee, S. P.
Multicomponent homogeneous, ultrapure noncrystalline gels/gel derived glasses are promising batch materials for the containerless glass melting experiments in microgravity. Hence, ultrapure, homogeneous gel precursors could be used to: (1) investigate the effect of the container induced nucleation on the glass forming ability of marginally glass forming compositions; and (2) investigate the influence of gravity on the phase separation and coarsening behavior of gel derived glasses in the liquid-liquid immiscibility zone of the nonsilicate systems having a high density phase. The structure and crystallization behavior of gels in the SiO2-GeO2 as a function of gel chemistry and thermal treatment were investigated. As are the chemical principles involved in the distribution of a second network former in silica gel matrix being investigated. The procedures for synthesizing noncrystalline gels/gel-monoliths in the SiO2-GeO2, GeO2-PbO systems were developed. Preliminary investigations on the levitation and thermal treatment of germania silicate gel-monoliths in the Pressure Facility Acoustic Levitator were done.
Mora, T; Mora, Thierry; Boudaoud, Arezki
The patterns arising from the differential swelling of gels are investigated experimentally and theoretically as a model for the differential growth of living tissues. Two geometries are considered: a thin strip of soft gel clamped to a stiff gel, and a thin corona of soft gel clamped to a disk of stiff gel. When the structure is immersed in water, the soft gel swells and bends out of plane leading to a wavy periodic pattern which wavelength is measured. The linear stability of the flat state is studied in the framework of linear elasticity using the equations for thin plates. The flat state is shown to become unstable to oscillations above a critical swelling rate and the computed wavelengths are in quantitative agreement with the experiment.
Miravet, Juan F
There is much recent interest in the field of molecular gels because of their potential use in many different applications including biomedicine and electronic materials. Functional Molecular Gels details the latest research on molecular gels from the fundamentals of molecular gel formation to their uses in a variety of fields. The book introduces the key concepts of designing molecular gels and their characterization techniques, followed by chapters discussing different stimuli responsive systems. Specific chapters are then dedicated to the diverse range of applications including catalysis, tissue engineering, photonic materials and as templates for nanostructured materials. Written by active researchers in the area, this book gives a taste of the possibilities that molecular gels offer for those both new to and already working in the area.
Evaluation of efficacy of saponin and freund's incomplete adjuvanted paratuberculosis vaccine in murine model
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Jubeda Begum
Full Text Available Aim: To compare the efficacy between saponin adjuvanted paratuberculosis killed vaccine and Freund's incomplete (FIC adjuvanted paratuberculosis vaccine in mice model. Materials and Methods: The study was conducted for a period of 11 months using 80 Swiss albino mice by dividing into four groups (Group I-mice vaccinated with killed Mycobacterium avium subspp. paratuberculosis (MAP adjuvanted with saponin, Group II- for FIC, Group III- Saponin control and Gr IV- FIC control. Faecal shedding, changes in body weight, presence of local reactions and clinical symptoms, were evaluated. Serological assays for humoral and cell mediated immune response were determined by agar gel immunodiffusion (AGID and nitric oxide test (NO respectively. A total of 76 serum samples, 52 faecal samples and 20 tissue samples were collected at different intervals during the study period. ZN staining; AGID test and nitric oxide test were employed for analysis of samples. Results: A total of 38 samples (37 faecal and 1 tissue sample and 18 serum samples were recorded as positive by ZN staining and AGID test respectively from all four groups of mice. Significant decrease in faecal shedding of organisms was observed in Group I mice vaccinated with saponin adjuvanted vaccine in comparison to Group II. Gain in body weight of Group I mice was recorded as higher than Group II. NO test revealed increase in the concentration of NO level in both vaccinated group but more significant in Group I. Conclusion: The tests results obtained revealed that killed MAP vaccine adjuvanted with saponin have higher protective efficacy in terms of reduced faecal shedding, gain in body weight, less side effects, absence of attributable specific symptoms of Johne's disease, etc. in comparison to killed MAP vaccine adjuvanted with FIC. The present study also reveals that AGID and NO estimation tests are specific tests which can be employed for diagnosis and comparison of efficacy of paratuberculosis vaccine.
Modeling chemoresponsive polymer gels.
Kuksenok, Olga; Deb, Debabrata; Dayal, Pratyush; Balazs, Anna C
Stimuli-responsive gels are vital components in the next generation of smart devices, which can sense and dynamically respond to changes in the local environment and thereby exhibit more autonomous functionality. We describe recently developed computational methods for simulating the properties of such stimuli-responsive gels in the presence of optical, chemical, and thermal gradients. Using these models, we determine how to harness light to drive shape changes and directed motion in spirobenzopyran-containing gels. Focusing on oscillating gels undergoing the Belousov-Zhabotinksy reaction, we demonstrate that these materials can spontaneously form self-rotating assemblies, or pinwheels. Finally, we model temperature-sensitive gels that encompass chemically reactive filaments to optimize the performance of this system as a homeostatic device for regulating temperature. These studies could facilitate the development of soft robots that autonomously interconvert chemical and mechanical energy and thus perform vital functions without the continuous need of external power sources. PMID:24498954
Energy Technology Data Exchange (ETDEWEB)
Sudo, M. [Shizuoka Univ., Shizuoka (Japan)
Gel being swollen by water is named hydrogel, and is adopted in the field of medicine such as slow release drug in drug delivery system, artificial muscles, and intelligent materials developing function by responding to irritation. Water in gel has strong mutual action with chain of polymer, and water not freezing in 0 degree C exists. This kind of water is orientated directly with functional group of gel, and is called non-freezing water by reason of not freezing in -196 degree C. Water being orientated loosely around non-freezing water is called bound water, and can be distinguish from free water freezing 0 degree C. Factors giving influence to speed of swelling and shrinking are size of gel and porosity. As of response time being in proportion to square of representative length of gel, velocity of response is fast by the size of gel being as fine as possible. The soft contact lens developed in Czechoslovakia in 1960 is poly-hydroxy-ethyl-cellulose gel. The permeability of oxygen is superior due to moisture content being increased. Furthermore, the devise releasing insulin responding glucose is developed. (NEDO)
Microfluidics with Gel Emulsions
Priest, Craig; Surenjav, Enkhtuul; Herminghaus, Stephan; Seemann, Ralf
Microfluidic processing is usually achieved using single phase liquids. Instead, we use monodisperse emulsions to compartment liquids within microchannel geometries. At low continuous phase volume fractions, droplets self-organize to form well-defined arrangements, analogous to foam. While it is well-known that confined geometries can induce rearrangement of foam compartments at the millimeter-scale, similar dynamics are also expected for gel emulsions. We have studied online generation, organization and manipulation of gel emulsions using a variety of microchannel geometries. ``Passive'' reorganization, based on fixed channel geometries, can be supplemented by ``active'' manipulation by incorporating a ferrofluid phase. A ferromagnetic phase facilitates reorganization of liquid compartments on demand using an electromagnetic trigger. Moreover, coalescence between adjacent compartments within a gel emulsion can be induced using electrical potential. Microfluidics using gel emulsions will be well-suited for combinatorial chemistry, DNA sequencing, drug screening and protein crystallizations.
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Lagerge S.
Full Text Available Aerogel conditioning of the chitosan makes it possible to prepare porous solids of significant specific surface. The increase in the chitosan concentration or the degree of acetylation decreases the specific surface of the synthesized chitosan gel. Whereas drying with supercritical CO2 more effectively makes it possible to preserve the volume of the spheres of gel and to have a more significant specific surface in comparison with evaporative drying.
Conformance Improvement Using Gels
Energy Technology Data Exchange (ETDEWEB)
Seright, Randall S.; Schrader, Richard; II Hagstrom, John; Wang, Ying; Al-Dahfeeri, Abdullah; Gary, Raven; Marin; Amaury; Lindquist, Brent
This research project had two objectives. The first objective was to identify gel compositions and conditions that substantially reduce flow through fractures that allow direct channeling between wells, while leaving secondary fractures open so that high fluid injection and production rates can be maintained. The second objective was to optimize treatments in fractured production wells, where the gel must reduce permeability to water much more than that to oil.
3D MR gel dosimetry with lung equivalent gel
International Nuclear Information System (INIS)
The MR gel dosimetry is used to verify complex 3D treatment plans. Till now this method served only for dose evaluation in homogeneous phantoms. On the way to build a heterogeneous anthropomorphic gel phantom, a lung equivalent gel with the density 0.4 g/cm3 was developed. First experiments show a 1.55 times higher dose reponse in the low density gel (LD gel). The comparison of a dose distribution in a gel/LD gel/gel slab phantom with Monte Carlo calculations shows good agreement within 5%. More over the accuray of the measuring device magnetic resonance imager was studied in respect to the now exclusive digital image processing with the software MRD (MR dosimetry). Because of the dimensions of the Fricke gel phantom an artefact correction, based on the data from the unirradiated phantom proved to be essential. (orig.)
Seroepidemiology of Paracoccidioides brasiliensis infection in horses from Rio Grande do Sul, Brazil
Scientific Electronic Library Online (English)
Ana Paula Neuschrank, Albano; Gabriel Baracy, Klafke; Tchana Martinez, Brandolt; Vanusa Pousada, Da Hora; Carlos Eduardo Wayne, Nogueira; Melissa Orzechowski, Xavier; Mário Carlos Araújo, Meireles.
Full Text Available Paracoccidioides brasiliensis is the etiological agent of the major systemic mycosis in Brazil, called paracoccidioidomycosis. Although the Rio Grande do Sul is considered an endemic area of the disease, there are few studies on the ecology of P. brasiliensis in the state. Therefore, this study aime [...] d to evaluate the infection of P. brasiliensis in horses from the mesoregion of Southwest Riograndense, using these animals as sentinels. Serological techniques, such as double immunodiffusion in agar gel (AGID) and indirect ELISA, were performed to detect the anti-gp43 P. brasiliensis antibody in horses from five different farms in the region of Bagé, RS, Brazil. Serology was performed in 200 Pure Blood English horses up to two years of age that were born and raised exclusively at the farms. Of these horses, 12% had anti-gp43 antibodies according to the ELISA results, with rates ranging from 0 to 30% according to the farm of origin (p
International Nuclear Information System (INIS)
Small Angle Neutron Scattering (SANS) measurements have been performed to investigate the nanoscale structure of materials of the systems xTiO2-(1-x)SiO2 and xZrO2-(1-x)SiO2 with x ? 10 mol % at different processing stages. The materials were prepared by sol-gel using the alkoxides method, in strong acidic conditions. Samples were studied as xerogels heat-treated at 120 and 850 deg. C and as wet gels at gel point and after aging. All samples showed identical microstructure at gel point, extended linear chains ?10 nm long. The aged gel has a mass fractal structure with fractal dimension of 1.7 - 1.9. The 120 deg. C heat-treated xerogels show homogeneous oxide regions with mass fractal structure. For the 850 deg. C heat-treated xerogel the oxide regions average size has reduced and it has densified as compared to 120 deg. C heat-treated sample. (author)
Schreiner, L. J.; Olding, T.; McAuley, K. B.
Polymer gels are chemical dosimeters based on dose dependent radiation-induced polymerization and cross-linking of monomers in an irradiated volume. The changes are spatially localized in the volume by incorporating the initial monomers in an aqueous gel matrix in the dosimeter and can be probed by various imaging techniques such as magnetic resonance imaging (MRI), x-ray computed tomography (CT), and optical CT. As they are chemical dosimeters, polymer gels are sensitive to preparation conditions. The three dimensional dose readout is sensitive to the imaging modality and also to the technical conditions in use during specific scans. This brief article is intended to present an introduction to these points which need to be taken into account as one attempts to establish this dosimetry in the clinic.
International Nuclear Information System (INIS)
Sol-gel techniques can be used to produce two new types of optical silicas, termed Type V for the full density material and Type VI for the optically transparent porous material. This paper summarizes the processing differences between these six types of commercial silicas. The primary emphasis of this paper is to discuss the scientific basis for the processing of Types V and VI optical silica. First, however, the use of sol-gel processing of other systems will be briefly reviewed. The controlled hydrolysis of alkoxides has also been used to produce submicrometer TiO2, doped TiO2 (17), ZrO2 (18), doped ZrO2 (18), doped SiO2 (19), SrTiO3 (20), and corderite (20) powders. Emulsions have been employed to produce spherical powders of mixed cation oxides, such as yttrium aluminum garnets (YAG) and many other systems (20). Sol-gel powder processes have also been applied to fissile elements (21) where spray form sols UO2, and rigid gel spheres of UO-PuO2 are formed during passage through a column of heated liquid. Both crystalline and vitreous ceramic fibers have been prepared using the sol-gel method. Compositions include TiO2-SiO2 and ZrO2-SiO2 glass fibers (22), high purity SiO2 waveguide fibers (23), Al2O3, ZrO2, ThO2, MgO, TiO2, ZrSiO4, 3AlO3-2SiO24, 3AlO3-2SiO2 fibers (24). Sol-gel derived alumina grains are important commercial products (25)
Janice Stephens
In this experiment related to plant biotechnology, learners discover how to prepare and load an electrophoresis gel. They will then run the gels in an electrophoresis system to separate several dyes that are of different molecular sizes and carry different charges. This technique is fundamental to many of the procedures used in biotechnology. This lesson guide includes background information for the educator, safety precautions, and questions with answers for learners. For safety reasons, adult supervision is recommended. Modifications for use with younger learners are described in a related PDF (see related resource).
Chen, Daniel
Active networks drive a diverse range of critical processes ranging from motility to division in living cells, yet a full picture of their rheological capabilities in non-cellular contexts is still emerging, e.g., How does the rheological response of a network capable of remodeling under internally-generated stresses differ from that of a passive biopolymer network? In order to address this and other basic questions, we have engineered an active gel composed of microtubules, bidirectional kinesin motors, and molecular depletant that self-organizes into a highly dynamic network of active bundles. The network continually remodels itself under ATP-tunable cycles of extension, buckling, fracturing, and self-healing. Using confocal rheometry we have simultaneously characterized the network's linear and non-linear rheological responses to shear deformation along with its dynamic morphology. We find several surprising and unique material properties for these active gels; most notably, rheological cloaking, the ability of the active gel to drive large-scale fluid mixing over several orders of flow magnitude while maintaining an invariant, solid-like rheological profile and spontaneous flow under confinement, the ability to exert micro-Newton forces to drive persistent directed motion of the rheometer tool. Taken together, these results and others to be discussed highlight the rich stress-structure-dynamics relationships in this class of biologically-derived active gels.
Hinkley, Craig
This video from CUNY Kingsborough Community College shows the process of running an agarose gel. The video describes the process step by step and would be easy to replicate in a laboratory setting. Running time for the video is 2:52.
Hinkley, Craig
This video from CUNY Kingsborough Community College shows how to pour an Agarose Gel. The video describes the process step by step and would be easy to replicate in a laboratory setting. Running time for the video is 2:13.
Toxoplasmosis, leptospirosis and brucellosis in stray dogs housed at the shelter in Umuarama municipality, Paraná, Brazil
Scientific Electronic Library Online (English)
Márcia Küster de Paula, Dreer; Daniela Dib, Gonçalves; Isabel Cristina da Silva, Caetano; Edson, Gerônimo; Paulo Henrique, Menegas; Danilo, Bergo; Fabiana Maria Ruiz, Lopes-Mori; Aline, Benitez; Julio Cesar de, Freitas; Fernanda, Evers; Italmar Teodorico, Navarro; Lisiane de Almeida, Martins.
Full Text Available Background : Leptospirosis, toxoplasmosis and brucellosis are diseases with worldwide distribution. Among stray dogs, these zoonoses are facilitated by direct contact with other animal species, by the habit of scavenging garbage and hunting in search of food, drinking standing water, smelling othe [...] r animals' urine, licking female genitalia and the sexual act itself. The objective of this study was to detect antibodies anti-Toxoplasma gondii, anti-Leptospira spp., anti-Brucella canis and anti-Brucella abortus in stray dogs housed in shelters at Umuarama city, Paraná, Brazil. In order to detect toxoplasmosis, indirect immunofluorescence assay (IFA) was performed, agglutination microscopic (MAT) test for leptospirosis and agar gel immunodiffusion (AGID) and buffered acidified antigen (BAA) tests for brucellosis. Results : Of the 175 serum samples analyzed, 70.85% were considered positive for toxoplasmosis by IFA, 20% by MAT for leptospirosis and 2.85% by AGID for Brucella canis. Conclusions : The serological results of this study showed that stray dogs housed at the private shelter are potential carriers of these three different zoonoses and contribute to the spread and maintenance of these etiologic agents in the urban area of Umuarama (PR), Brazil.
Clinical resolution of Brucella canis-induced ocular inflammation in a dog.
Vinayak, Arathi; Greene, Craig E; Moore, Phillip A; Powell-Johnson, Gail
A 2-year-old spayed female mixed-breed dog was referred with an 8-month history of recurrent bilateral anterior uveitis and hyphema secondary to infection with Brucella canis. Treatment with doxycycline PO and atropine and prednisone acetate topically prior to referral had failed to resolve the ocular inflammation. Successful control of ocular inflammation was achieved after initiation of treatment with gentamicin SC and ciprofloxacin and doxycycline PO. The finite indirect fluorescent antibody (IFA) titer was reduced by half, and results of an agar gel immunodiffusion (AGID) test became negative after rifampin was added to the treatment protocol. Treatment with gentamicin was eventually discontinued because of evidence of renal toxicosis and cutaneous reactions to repeated injections. Thirty-five months after initial examination of the dog, results of the AGID test were still negative, the finite IFA titer was stable, and ocular inflammation had resolved, suggesting that the ocular infection may have been eliminated. To our knowledge, this represents the first report of the successful treatment of ocular inflammation caused by B canis infection in a dog. PMID:15198266
Gel architectures and their complexity.
Richtering, Walter; Saunders, Brian R
Gels have made the transition from brittle materials with few potential applications to high performance systems with mechanical properties approaching that of rubber. They have a wide variety of structures and provide the opportunity to tailor these structures to achieve well-controlled properties over a range of length scales. In this review we consider and compare the structures and properties of a range of gels that have been studied in recent years. In comparing these gels we highlight the importance of key structural parameters in defining gel mechanical properties. It is hoped that this article will provide authors who discover new gels a resource that will easily enable them to determine the differences of their new gels to existing gels. PMID:24705716
International Nuclear Information System (INIS)
The development of a national policy for guaranteeing an ample supply of 99mTc to nuclear medicine, involves issues which go beyond the means by which radioactivation is achieved. Indeed, in such an exercise the pragmatic dictates of business and the sensitivities of politics must also be taken into account. Furthermore where a preference towards the nuclear reactor or the potential of cyclotrons is being questioned, the debate is incomplete if the only options that are considered are the fission-based 99Mo generator versus the direct cyclotron production of 99mTc. There is a third option (also neutron ?-based), an alternative to the fission 99Mo generator, which ought not be overlooked. The application of low specific activity (n,?) 99Mo to a new type of generator, the Gel Generator, has been the focus of much research, particularly in Australia and more recently in China. After the initial concept had been established in the laboratory, the Australian researchers then undertook a comprehensive program of tests on the Gel Generator to assess its potential, either in the clinical laboratory or the centralised radiopharmacy, for supplying 99mTc suitable for nuclear medicine. The outcome of this program was a clear indication that the Gel Generator innovation had the capability to provide both technical and economic advantages to the nuclear medicine industry. These advantages are described. Since that time the Gel Generator has been selected for routine use in China where it now satisfies more than 30% of the 99mTc demand. (author)
Czech Academy of Sciences Publication Activity Database
Mat?jová, Lenka; Cajthaml, Tomáš; Kluso?, P.; Benada, Old?ich; Mat?j, Z.; Šolcová, Olga
Bratislava : Slovak Society of Chemical Engineering, 2008 - (Markoš, J.), s. 166 ISBN 978-80-227-2903-1. [35th International Conference of Slovak Society of Chemical Engineering. Tatranské Matliare (SK), 26.05.2008-30.05.2008] R&D Projects: GA AV ?R KAN400720701; GA AV ?R IAA4072404 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z50200510 Keywords : sol-gel * TiO2 powder * supercritic fluid extraction Subject RIV: CF - Physical ; Theoretical Chemistry
Gel polymer electrolytes for batteries
Balsara, Nitash Pervez; Eitouni, Hany Basam; Gur, Ilan; Singh, Mohit; Hudson, William
Nanostructured gel polymer electrolytes that have both high ionic conductivity and high mechanical strength are disclosed. The electrolytes have at least two domains--one domain contains an ionically-conductive gel polymer and the other domain contains a rigid polymer that provides structure for the electrolyte. The domains are formed by block copolymers. The first block provides a polymer matrix that may or may not be conductive on by itself, but that can soak up a liquid electrolyte, thereby making a gel. An exemplary nanostructured gel polymer electrolyte has an ionic conductivity of at least 1.times.10.sup.-4 S cm.sup.-1 at 25.degree. C.
Phase behaviors of agarose gel
Takaharu Morita; Takayuki Narita; Sada-atsu Mukai; Miho Yanagisawa; Masayuki Tokita
We present evidence for the existence of phase separation in the gel state of agarose having the mixture of water and methanol as the gel solvent. Firstly, the sol-gel transition line and the cloud point line are determined independently as a function of the concentration of agarose as well as the concentration of methanol in the mixed solvent by the quasi-equilibrium cooling of the solutions. Then the spinodal line is determined by quenching the solutions below the sol-gel transition line. W...
Electrically controlled polymeric gel actuators
Adolf, Douglas B. (Albuquerque, NM); Shahinpoor, Mohsen (Albuquerque, NM); Segalman, Daniel J. (Albuquerque, NM); Witkowski, Walter R. (Albuquerque, NM)
Electrically controlled polymeric gel actuators or synthetic muscles capable of undergoing substantial expansion and contraction when subjected to changing pH environments, temperature, or solvent. The actuators employ compliant containers for the gels and their solvents. The gels employed may be cylindrical electromechanical gel fibers such as polyacrylamide fibers or a mixture of poly vinyl alcohol-polyacrylic acid arranged in a parallel aggregate and contained in an electrolytic solvent bath such as salt water. The invention includes smart, electrically activated devices exploiting this phenomenon. These devices are capable of being manipulated via active computer control as large displacement actuators for use in adaptive structure such as robots.
Phase behaviors of agarose gel
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Takaharu Morita
Full Text Available We present evidence for the existence of phase separation in the gel state of agarose having the mixture of water and methanol as the gel solvent. Firstly, the sol-gel transition line and the cloud point line are determined independently as a function of the concentration of agarose as well as the concentration of methanol in the mixed solvent by the quasi-equilibrium cooling of the solutions. Then the spinodal line is determined by quenching the solutions below the sol-gel transition line. We find that the spinodal line appears below the cloud point line and both lines are entirely buried below the sol-gel transition line in the aqueous agarose system. The concentration fluctuations are, therefore, frozen into the polymer network of agarose gel that promotes the opacity of the resultant gel. The structure of agarose gel is observed by the confocal laser scanning microscope (CLSM imaging technique that reveals that the density fluctuations are grown up to micrometer scale in space. The phase separation boundary is found to shift to the higher temperature region than the sol-gel transition line when the concentration of methanol in the mixed solvent is increased. The results indicate that the position of the phase separation boundary in relative to the sol-gel transition line varies with the quality of solvent. These results are in agreement with the theory of the sol-gel transition in which both the divergence of the connectivity and the thermodynamic instability are taken into account.
Inquérito sorológico e fatores de risco para a brucelose por Brucella canis em căes do município de Santana de Parnaíba, Estado de Săo Paulo / Serological survey and risk factors for brucellosis due to Brucella canis in dogs of the Santana de Parnaíba municipality, State of Săo Paulo
Scientific Electronic Library Online (English)
Sérgio S., Azevedo; Sílvio A., Vasconcellos; Clebert J., Alves; Lara B., Keid; Lília M.P. S., Grasso; Roberta, Mascolli; Sônia R., Pinheiro.
Full Text Available Foi investigada a prevalęncia da brucelose causada por Brucella canis em căes do município de Santana de Parnaíba, SP, Brasil, e realizado um estudo de possíveis fatores de risco associados ŕ soropositividade para B. canis. Foram examinadas 410 amostras de soro sanguíneo de căes colhidas durante a c [...] ampanha de vacinaçăo anti-rábica animal, realizada em agosto de 1999. A imunodifusăo em gel de ágar (IDGA), utilizando antígeno de lipopolissacarídeos e proteínas de Brucella ovis, amostra Reo 198, foi empregada em soros normais como teste de triagem, e, para a confirmaçăo, a mesma técnica foi aplicada em soros tratados pelo 2-mercaptoetanol (IDGA-ME). A reaçăo de fixaçăo de complemento (CFT), utilizando antígeno de B. ovis, amostra 63/290, também foi utilizada como prova confirmatória. A determinaçăo da prevalęncia considerou como positivos os animais que reagiram positivamente nos dois testes confirmatórios (IDGA-ME e CFT). A prevalęncia da B. canis foi de 2,2% (I.C. 95% = 1,01-4,13%). A análise estatística mostrou que os căes com acesso irrestrito ŕ rua o dia todo (manejo do tipo solto) estiveram mais expostos ao risco da infecçăo por B. canis, com um valor de odds ratio de 8,73 (I.C. 95% = 1,48-51,55) e p=0,04. Abstract in english The prevalence of brucellosis due to Brucella canis was investigated in dogs of the Santana de Parnaíba county, State of Săo Paulo, southeastern Brazil, and the risk factors for infection were analyzed. For this purpose, 410 blood samples were collected from dogs during the rabies vaccination campai [...] gn, in August 1999. The agar gel immunodiffusion test (AGID), using lipopolysaccharides and protein antigens from Brucella ovis, strain Reo 198, was applied first as a screening test on normal sera, and secondly, for confirmation. The same AGID test was applied to sera treated previously with 2-mercaptoethanol (ME-AGID). The complement fixation test (CFT), using B. ovis antigen, strain 63/290, was applied also as a confirmatory test. For the prevalence analysis, animals presenting positive results in both ME-AGID and CFT were considered positive. The prevalence of brucellosis due to B. canis was 2.2% (95% C.I.=1.01-4.13%). Dogs that were allowed by their owners to stay free outside their home had a higher risk for contracting B. canis infection, with an odds ratio value of 8.73 (95% C.I.=1.48-51.55) and p=0.04.
Seroprevalence for brucellosis and leptospirosis in dogs from Belém and Castanhal, State of Pará, Brazil / Soroprevalęncia para brucelose e leptospirose em căes de Belém e Castanhal, Pará, Brasil
Scientific Electronic Library Online (English)
Giselle Souza da, PAZ; Katarine de Souza, ROCHA; Michele de Souza, LIMA; Ediene Moura, JORGE; José Carlos Figueiredo, PANTOJA; Carla Cristina Guimarăes de, MORAES; Helio, LANGONI.
Full Text Available Brucelose e leptospirose săo enfermidades bacterianas amplamente disseminadas e o căo é importante fonte de infecçăo e reservatório para ambas, podendo eliminar o agente no meio ambiente, e transmiti-lo para humanos e/ou outros animais. O presente estudo teve como objetivo pesquisar a ocorręncia de [...] căes reagentes para anticorpos contra Leptospira spp., Brucella canis e B. abortus em Belém e Castanhal, Pará, Amazônia, Brasil. Foram colhidas de forma aleatória 156 amostras no município de Belém e 158 amostras em Castanhal. A pesquisa de anticorpos anti-B. canis foi realizada pela técnica de Imunodifusăo em Gel de Ágar (IDGA) com e sem tratamento do soro com 2-mercaptoetanol (IDGA-2ME) e para pesquisa de anticorpos anti-B. abortus foi utilizada a técnica de Soroaglutinaçăo Rápida com antígeno acidificado tamponado (AAT). Para pesquisa de anticorpos contra-Leptospira spp. utilizou-se a Técnica de Aglutinaçăo Microscópica (MAT). Nenhum animal reagiu para Brucella abortus e um animal foi reagente para B. canis na IDGA, porém foi negativo na IDGA-2ME. Dezessete por cento dos căes (47/274) apresentaram anticorpos contra-Leptospira spp., com predominância do sorovar Canicola. Os căes de Belém e Castanhal năo săo fontes de infecçăo para B. abortus e B. canis, no entanto săo reservatórios de diferentes sorovares de Leptospira spp. Abstract in english Brucellosis and leptospirosis are widely spread bacterial infections and dogs are the most important source of infection and reservoir for diseases. Dogs can disseminate the agents in the environment and transmit them to humans and/or other animals. The objective of this study was assess the occurre [...] nce of reactive to antibodies anti-Leptospira spp., Brucella canis and B. abortus in Belém and Castanhal, State of Pará, Amazon, Brazil. A total of 156 samples were randomly collected in the city of Belém and 158 samples in Castanhal. The anti-B. canis antibodies research was performed by Agar Gel Immunodiffusion (AGID) with and without 2-mercaptoethanol serum treatment (AGID-2ME). To assess the anti-B. abortus antibodies, the technique of Fast Seroagglutination with buffered acidified plate antigen (BAPAT) was used. For anti-Leptospira spp. antibodies research, the Microscopic Agglutination Technique (MAT) was used. No animal reacted to Brucella abortus and one animal was reactive to B. canis at the AGID, but it was negative to the AGID-2ME test. Seventeen percent of dogs (47/274) presented anti-Leptospira spp. antibodies, with prevalence of serovar Canicola. The dogs from Belém and Castanhal are not source of infection for B. abortus and B. canis, however, they are reservoirs for different serovars of Leptospira spp.
Nanocrystal/sol-gel nanocomposites
Petruska, Melissa A. (Los Alamos, NM); Klimov, Victor L. (Los Alamos, NM)
The present invention is directed to solid composites including colloidal nanocrystals within a sol-gel host or matrix and to processes of forming such solid composites. The present invention is further directed to alcohol soluble colloidal nanocrystals useful in formation of sol-gel based solid composites
Electrochemical Light-Emitting Gel
Directory of Open Access Journals (Sweden)
Nobuyuki Itoh
Full Text Available Light-emitting gel, a gel state electroluminescence material, is reported. It is composed of a ruthenium complex as the emitter, an ionic liquid as the electrolyte, and oxide nanoparticles as the gelation filler. Emitted light was produced via electrogenerated chemiluminescence. The light-emitting gel operated at low voltage when an alternating current was passed through it, regardless of its structure, which is quite thick. The luminescence property of the gel is strongly affected by nanoparticle materials. TiO2 nanoparticles were a better gelation filler than silica or ZnO was, with respect to luminescence stability, thus indicating a catalytic effect. It is demonstrated that the light-emitting gel device, with quite a simple fabrication process, flashes with the application of voltage.
International Nuclear Information System (INIS)
In radiotherapy, the primary objective is to deliver a prescribed dose of radiation to a tumour or lesion within a patient while minimising the dose delivered to the surrounding healthy tissue. Traditional radiotherapy treatments usually involve simple external or internal irradiations of a tumour. External irradiations are normally achieved in the clinic with photon or electron beams produced by high energy linear accelerators. The photon or electron beams are collimated into regular shapes as they emerge from the treatment head of the unit which is supported by a gantry that can be rotated isocentrically to any position. A discrete number of photon or electron beams with different angles of incidence that intersect at the iso-centre are used to produce a region of high dose around the tumour volume (positioned at the iso-centre). Internal irradiations are normally achieved in the clinic by implanting radioactive sources in and around the tumour or lesion. Such irradiations are characterised by very high doses local to the tumour. Radioactive sources are also used to prevent post-angioplasty restenosis by inserting sources into arteries. Usually when treating a tumour, a compromise is made between tumour control and complications arising from normal tissue damage. One measure of this compromise, the therapeutic ratio, is defined as the radiation dose producing complications in 50% of patients divided by the dose providing tumour control in 50% of the patients. The therapeutic ratio depends on the radiobiological characteristics of the cancerous tissue and surrounding healthy tissues and on the radiation dose distribution achieved by the radiotherapy treatment. It is generally believed that the therapeutic ratio can be minimised by optimising the conformation of the radiation dose distribution to the target volume. This is difficult with traditional radiotherapy techniques since they do not produce dose distributions that adequately cover tumour volumes of complex shapes and sizes while sparing normal tissue. The situation is further complicated if the normal tissues are critical organs or are particularly sensitive to radiation. Radiotherapy techniques employed to obtain a closer conformation of the dose distribution to the tumour volume are referred to as conformal radiotherapy techniques. The clinical implementation of conformal therapy has been delayed by limitations in the verification of conformal dose distributions calculated by treatment planning systems prior to the irradiation of the patient and the verification of complex treatments during its delivery to the patient. There are several aspects of conformal therapy that complicate dose verification. To achieve the dose distributions conforming to complex 3D volumes, high dose gradients arise in the treatment volume. Further, overdose or underdose regions can exist when separate radiation fields are used to deliver additional radiation. These aspects require that practical dose measurement (dosimetry) techniques be able to integrate dose over time and easily measure dose distributions in 3D with high spatial resolution. Traditional dosimeters, such as ion chambers, thermoluminescent dosimeters and radiographic film do not fulfil these requirements. Novel gel dosimetry techniques are being developed in which dose distributions can potentially be determined in vitro in 3D using anthropomorphic phantoms to simulate a clinically irradiated situation. As long ago as the 1950's, radiation-induced colour change in dyes was used to investigate radiation doses in gels. It was subsequently shown that radiation induced changes in nuclear magnetic resonance (NMR) relaxation properties of gels infused with conventional Fricke dosimetry solutions could be measured using magnetic resonance imaging (MRI). In Fricke gels, Fe2+ ions in ferrous sulphate solutions are usually dispersed throughout a gelatin, agarose or PVA matrix. Radiation-induced changes in the dosimeters are considered to be either through direct absorption of ionising radiation or via intermediate water free rad
Electromechanical nonionic gels
International Nuclear Information System (INIS)
The electrically induced bending of nonionic polyvinyl alcohol gels, bending over 900 within 100 ms, is the fastest motion in the field of electroactuation of polymers. This rapid bending produces initial mechanical vibrations followed by a durable displacement that contrasts highly with the relaxation observed with elastomer- and polyelectrolyte-based actuators. Here, we characterize the bending process using video imaging and laser detecting technology and establish a physical model for the electromechanical conversion, based on our observation of an induced solvent migration. Our results show excellent agreement between the measurements and calculations. This study provides general rules for understanding the electrically induced bending of isotropic dielectrics and may also shed light on nonmuscular biological engines
Electromechanical nonionic gels
Energy Technology Data Exchange (ETDEWEB)
Zheng, J [Department of Bioengineering, University of Washington, Seattle, WA 98195 (United States); Xu, C [Department of Mechanical Engineering, University of Washington, Box 352600, Seattle, WA 98195 (United States); Hirai, T [Faculty of Textile Science and Technology, Shinshu University, Tokida 3-15-1, Ueda-shi 386-8567 (Japan)], E-mail: firstname.lastname@example.com
The electrically induced bending of nonionic polyvinyl alcohol gels, bending over 90{sup 0} within 100 ms, is the fastest motion in the field of electroactuation of polymers. This rapid bending produces initial mechanical vibrations followed by a durable displacement that contrasts highly with the relaxation observed with elastomer- and polyelectrolyte-based actuators. Here, we characterize the bending process using video imaging and laser detecting technology and establish a physical model for the electromechanical conversion, based on our observation of an induced solvent migration. Our results show excellent agreement between the measurements and calculations. This study provides general rules for understanding the electrically induced bending of isotropic dielectrics and may also shed light on nonmuscular biological engines.
Chemical Gel for Surface Decontamination
International Nuclear Information System (INIS)
Many chemical decontamination processes operate by immersing components in aggressive chemical solutions. In these applications chemical decontamination technique produce large amounts of radioactive liquid waste. Therefore it is necessary to develop processes using chemical gels instead of chemical solutions, to avoid the well-known disadvantages of chemical decontamination techniques while retaining their high efficiency. Chemical gels decontamination process consists of applying the gel by spraying it onto the surface of large area components (floors, walls, etc) to be decontaminated. The gel adheres to any vertical or complex surface due to their thixotropic properties and operates by dissolving the radioactive deposit, along with a thin layer of the gel support, so that the radioactivity trapped at the surface can be removed. Important aspects of the gels are that small quantities can be used and they show thixitropic properties : liquid during spraying, and solid when stationary, allowing for strong adherence to surfaces. This work investigates the decontamination behaviors of organic-based chemical gel for SS 304 metallic surfaces contaminated with radioactive materials
Detecçăo de Erwinia psidii via enriquecimento em extrato de folhas de goiabeira e imunodifusăo radial dupla Detection of Erwinia psidii through enrichment in guava leaf extract and double radial immunodiffusion
Directory of Open Access Journals (Sweden)
Ana Cristina O. Teixeira
Full Text Available Uma das principais doenças que afetam a produçăo de goiaba no Brasil é a seca-dos-ponteiros, causada pela bactéria Erwinia psidii, cuja disseminaçăo é favorecida por mudas contaminadas. O desenvolvimento de métodos diagnósticos mais eficazes poderia reduzir a disseminaçăo da bactéria no país. Considerando a necessidade de se disponibilizar um método eficiente e simples para a detecçăo de E. psidii em material de propagaçăo, foi objetivo desse trabalho produzir antissoros policlonais específicos contra a bactéria e desenvolver um método de detecçăo utilizando o enriquecimento da populaçăo bacteriana em extrato de folhas de goiabeira seguido de imunodifusăo radial dupla. Um antissoro foi produzido contra a estirpe tipo da bactéria IBSBF 435 (ICMP 8426, NCPPB 3555, avaliado quanto ŕ eficięncia e especificidade e utilizado na determinaçăo dos limiares de detecçăo da mesma. O antissoro As15-1 reagiu positivamente com todos as estirpes testadas de E. psidii, năo reagindo com estirpes de outros gęneros e espécies de bactérias fitopatogęnicas e apresentou reaçăo cruzada com dois isolados năo patogęnicos da flora da goiabeira. O crescimento da populaçăo bacteriana no extrato de folhas foi observado após 12 h de incubaçăo a partir de populaçőes iniciais de 10ł, 10(5 e 10(7 ufc/mL, até 60 h. A partir de 12 h, já foi possível detectar E. psidii por enriquecimento e imunodifusăo radial nas amostras com populaçőes iniciais de 10(7 ufc/mL e a partir de 36 h, detectou-se a bactéria mesmo em amostras com populaçőes iniciais de 10ł ufc/mL. Considerando a possibilidade de falsos positivos, é recomendável associar outros métodos diagnósticos ao método aqui proposto.One of the most important diseases affecting guava production in Brazil is bacterial blight, caused by the bacterium Erwinia psidii. Pathogen dissemination often occurs through contaminated propagating plant material. The development of more effective diagnostic methods may reduce pathogen dissemination in the country. Considering the need for a reliable and simple method for detecting the pathogen in plant material, the objectives of this study were to produce E. psdii-specific polyclonal antibodies and to develop a detection method using bacterial population enrichment on guava leaf extracts followed by double radial immunodiffusion. The antiserum was produced against the E. psidii type strain IBSBF 435 (ICMP 8426, NCPPB 3555 and its efficiency, specificity and sensitivity threshold were determined. The antiserum As15-1 was tested with strains of several plant-pathogenic bacteria and reacted positively with all strains of E. psidii, although cross reactions were detected with two non-pathogenic isolates from guava flora. Bacterial multiplication on leaf extracts was observed 12 h after incubation from initial populations of 10ł, 10(5 and 10(7 ufc/mL, up to 60 h. After 12 h it was already possible to detect E. psidii in samples with starting populations of 10(7 cfu/mL. After 36 h, the enrichment technique allowed the detection of E. psidii using double radial immunodiffusion in samples with populations as low as 10ł cfu/mL. Considering the possibility of false positives it is desirable to associate other diagnostic methods with the method proposed in this study.
Detecçăo de Erwinia psidii via enriquecimento em extrato de folhas de goiabeira e imunodifusăo radial dupla / Detection of Erwinia psidii through enrichment in guava leaf extract and double radial immunodiffusion
Scientific Electronic Library Online (English)
Ana Cristina O., Teixeira; Marisa A.S.V., Ferreira; Abi S.A., Marques.
Full Text Available Uma das principais doenças que afetam a produçăo de goiaba no Brasil é a seca-dos-ponteiros, causada pela bactéria Erwinia psidii, cuja disseminaçăo é favorecida por mudas contaminadas. O desenvolvimento de métodos diagnósticos mais eficazes poderia reduzir a disseminaçăo da bactéria no país. Consid [...] erando a necessidade de se disponibilizar um método eficiente e simples para a detecçăo de E. psidii em material de propagaçăo, foi objetivo desse trabalho produzir antissoros policlonais específicos contra a bactéria e desenvolver um método de detecçăo utilizando o enriquecimento da populaçăo bacteriana em extrato de folhas de goiabeira seguido de imunodifusăo radial dupla. Um antissoro foi produzido contra a estirpe tipo da bactéria IBSBF 435 (ICMP 8426, NCPPB 3555), avaliado quanto ŕ eficięncia e especificidade e utilizado na determinaçăo dos limiares de detecçăo da mesma. O antissoro As15-1 reagiu positivamente com todos as estirpes testadas de E. psidii, năo reagindo com estirpes de outros gęneros e espécies de bactérias fitopatogęnicas e apresentou reaçăo cruzada com dois isolados năo patogęnicos da flora da goiabeira. O crescimento da populaçăo bacteriana no extrato de folhas foi observado após 12 h de incubaçăo a partir de populaçőes iniciais de 10ł, 10(5) e 10(7) ufc/mL, até 60 h. A partir de 12 h, já foi possível detectar E. psidii por enriquecimento e imunodifusăo radial nas amostras com populaçőes iniciais de 10(7) ufc/mL e a partir de 36 h, detectou-se a bactéria mesmo em amostras com populaçőes iniciais de 10ł ufc/mL. Considerando a possibilidade de falsos positivos, é recomendável associar outros métodos diagnósticos ao método aqui proposto. Abstract in english One of the most important diseases affecting guava production in Brazil is bacterial blight, caused by the bacterium Erwinia psidii. Pathogen dissemination often occurs through contaminated propagating plant material. The development of more effective diagnostic methods may reduce pathogen dissemina [...] tion in the country. Considering the need for a reliable and simple method for detecting the pathogen in plant material, the objectives of this study were to produce E. psdii-specific polyclonal antibodies and to develop a detection method using bacterial population enrichment on guava leaf extracts followed by double radial immunodiffusion. The antiserum was produced against the E. psidii type strain IBSBF 435 (ICMP 8426, NCPPB 3555) and its efficiency, specificity and sensitivity threshold were determined. The antiserum As15-1 was tested with strains of several plant-pathogenic bacteria and reacted positively with all strains of E. psidii, although cross reactions were detected with two non-pathogenic isolates from guava flora. Bacterial multiplication on leaf extracts was observed 12 h after incubation from initial populations of 10ł, 10(5) and 10(7) ufc/mL, up to 60 h. After 12 h it was already possible to detect E. psidii in samples with starting populations of 10(7) cfu/mL. After 36 h, the enrichment technique allowed the detection of E. psidii using double radial immunodiffusion in samples with populations as low as 10ł cfu/mL. Considering the possibility of false positives it is desirable to associate other diagnostic methods with the method proposed in this study.
Scientific Electronic Library Online (English)
Full Text Available The main goal of this work is the preparation and characterization of gelsusingchitosan for further formulation and topic applications. To achieve this goal several gels from pharmaceutical quality chitosan of low( Mw= 72.180 g/mol ) andmedium.( Mw= 103.000 g/mol) molecular weight with a 4% w/w were [...] employed.The prepared gels were characterized by infrared spectroscopy, scanning electron microscopy andreological analyses.The spectroscopic study shows no great difference between both gels and most of chitosan bands are exhibited.The reological studies shows that both gels exhibit a non newtonian flow independent of the time, with seudoplastic for low molecular weight chitosan and plastic behavior for the medium molecular weight
Relación entre la prueba intradermica de histoplasmina y los niveles de anticuerpos detectables por ELISA e immunodifusion Relationship between histoplasmin skin test and Histoplasma capsulatum antibody levels detected by ELISA and immunodiffusion tests
Directory of Open Access Journals (Sweden)
Carlos M. Fernandez-Andreu
Full Text Available Se realizó un estudio prospectivo en 40 trabajadores de una granja avícola (grupo 1 considerados con riesgo de exposición a Histoplasma capsulatum, agente etiológico de la histoplasmosis, y en 16 individuos sin riesgo profesional de exposición a dicho agente (grupo 2. En ambos grupos se aplicó la prueba intradérmica de histoplasmina y se obtuvo el suero antes de su aplicación y a los 30 y 180 días después de realizada dicha prueba. Se determinó el nivel de anticuerpos anti-H. capsulatum mediante las técnicas de ELISA e inmunodifusión doble. En los dos grupos de población estudiados la aplicación intradérmica de histoplasmina, aún en los casos en que la respuesta fue positiva, no constituyó un estímulo antigénico suficiente para provocar un aumento en los niveles de anticuerpos anti-H. capsulation detectables por las técnicas serológicas empleadas. Los resultados obtenidos contribuyen a la mejor interpretación de la prueba de ELISA en el diagnóstico de la histoplasmosis.A prospective study was carried out in two groups of individuals: a group 1 (n=40 included workers from a poultry farm, with potencial occupational risk of exposure to Histoplasma capsulatum, ethiologic agent of histoplasmosis, and a group 2 (n=16, persons without occupational risk of exposure to the agent. Histoplasmin skin test was performed in both groups, and three sera were obtained from each individual: 1 before skin test was done, 2 30 days after, and 3 180 days after it. In both groups the histoplasmin skin test, even when the test was positive, was not a sufficient antigenic booster to provoque an increase in the H. capsulatum antibody levels capable to be detected by the Serologic tests used (ELISA and Double Immunodiffusion. These results contribute to improve the interpretation of ELISA test values in the diagnosis of histoplasmosis.
Relación entre la prueba intradermica de histoplasmina y los niveles de anticuerpos detectables por ELISA e immunodifusion / Relationship between histoplasmin skin test and Histoplasma capsulatum antibody levels detected by ELISA and immunodiffusion tests
Scientific Electronic Library Online (English)
Carlos M., Fernandez-Andreu; Ana Margarita, Cadre-Raton; Gerardo, Martinez Machin; Alina Llop, Hernandez; Miguel, Suarez Hernandez.
Full Text Available Se realizó un estudio prospectivo en 40 trabajadores de una granja avícola (grupo 1) considerados con riesgo de exposición a Histoplasma capsulatum, agente etiológico de la histoplasmosis, y en 16 individuos sin riesgo profesional de exposición a dicho agente (grupo 2). En ambos grupos se aplicó la [...] prueba intradérmica de histoplasmina y se obtuvo el suero antes de su aplicación y a los 30 y 180 días después de realizada dicha prueba. Se determinó el nivel de anticuerpos anti-H. capsulatum mediante las técnicas de ELISA e inmunodifusión doble. En los dos grupos de población estudiados la aplicación intradérmica de histoplasmina, aún en los casos en que la respuesta fue positiva, no constituyó un estímulo antigénico suficiente para provocar un aumento en los niveles de anticuerpos anti-H. capsulation detectables por las técnicas serológicas empleadas. Los resultados obtenidos contribuyen a la mejor interpretación de la prueba de ELISA en el diagnóstico de la histoplasmosis. Abstract in english A prospective study was carried out in two groups of individuals: a group 1 (n=40) included workers from a poultry farm, with potencial occupational risk of exposure to Histoplasma capsulatum, ethiologic agent of histoplasmosis, and a group 2 (n=16), persons without occupational risk of exposure to [...] the agent. Histoplasmin skin test was performed in both groups, and three sera were obtained from each individual: 1) before skin test was done, 2) 30 days after, and 3) 180 days after it. In both groups the histoplasmin skin test, even when the test was positive, was not a sufficient antigenic booster to provoque an increase in the H. capsulatum antibody levels capable to be detected by the Serologic tests used (ELISA and Double Immunodiffusion). These results contribute to improve the interpretation of ELISA test values in the diagnosis of histoplasmosis.
Topical Review: Polymer gel dosimetry
Baldock, C; De Deene, Y; Doran, S; Ibbott, G.; Jirasek, A; Lepage, M.; McAuley, K B; Oldham, M; Schreiner, L J
Polymer gel dosimeters are fabricated from radiation sensitive chemicals which, upon irradiation, polymerize as a function of the absorbed radiation dose. These gel dosimeters, with the capacity to uniquely record the radiation dose distribution in three-dimensions (3D), have specific advantages when compared to one-dimensional dosimeters, such as ion chambers, and two-dimensional dosimeters, such as film. These advantages are particularly significant in dosimetry situations where steep dose ...
Tracer diffusion in colloidal gels
Babu, Sujin; Gimel, Jean Christophe; Nicolai, Taco
Computer simulations were done of the mean square displacement (MSD) of tracer particles in colloidal gels formed by diffusion or reaction limited aggregation of hard spheres. The diffusion coefficient was found to be determined by the volume fraction accessible to the spherical tracers ($\\phi_a$) independent of the gel structure or the tracer size. In all cases, critical slowing down was observed at $\\phi_a\\approx 0.03$ and was characterized by the same scaling laws reporte...
Microbubble tunneling in gel phantoms
Caskey, Charles F.; Qin, Shengping; Dayton, Paul A.; Ferrara, Katherine W.
Insonified microbubbles were observed in vessels within a gel with a Young's modulus similar to that of tissue, demonstrating shape instabilities, liquid jets, and the formation of small tunnels. In this study, tunnel formulation occurred in the direction of the propagating ultrasound wave, where radiation pressure directed the contact of the bubble and gel, facilitating the activity of the liquid jets. Combinations of ultrasonic parameters and microbubble concentrations that are relevant f...
TOPICAL REVIEW: Polymer gel dosimetry
Baldock, C.; De Deene, Y.; Doran, S.; Ibbott, G.; Jirasek, A.; Lepage, M.; McAuley, K. B.; Oldham, M.; Schreiner, L. J.
Polymer gel dosimeters are fabricated from radiation sensitive chemicals which, upon irradiation, polymerize as a function of the absorbed radiation dose. These gel dosimeters, with the capacity to uniquely record the radiation dose distribution in three-dimensions (3D), have specific advantages when compared to one-dimensional dosimeters, such as ion chambers, and two-dimensional dosimeters, such as film. These advantages are particularly significant in dosimetry situations where steep dose gradients exist such as in intensity-modulated radiation therapy (IMRT) and stereotactic radiosurgery. Polymer gel dosimeters also have specific advantages for brachytherapy dosimetry. Potential dosimetry applications include those for low-energy x-rays, high-linear energy transfer (LET) and proton therapy, radionuclide and boron capture neutron therapy dosimetries. These 3D dosimeters are radiologically soft-tissue equivalent with properties that may be modified depending on the application. The 3D radiation dose distribution in polymer gel dosimeters may be imaged using magnetic resonance imaging (MRI), optical-computerized tomography (optical-CT), x-ray CT or ultrasound. The fundamental science underpinning polymer gel dosimetry is reviewed along with the various evaluation techniques. Clinical dosimetry applications of polymer gel dosimetry are also presented.
Silica reinforced triblock copolymer gels
DEFF Research Database (Denmark)
Theunissen, E.; Overbergh, N.
The effect of silica and polymer coated silica particles as reinforcing agents on the structural and mechanical properties of polystyrene-poly(ethylene/butylene)-polystyrene (PS-PEB-PS) triblock gel has been investigated. Different types of chemically modified silica have been compared in order to evaluate the influence of the compatibility between gel and filler. Time-resolved SANS and small-angle X-ray scattering (SAXS) shows that the presence of silica particles affects the ordering of the polystyrene domains during gelsetting. The scattering pattern of silica-reinforced gels reveals strong scattering at very low q, but no structure and formfactor information. However, on heating above the viscoelastic to plastic transition, the 'typical' scattering pattern of the copolymer gel builds-up. All reinforced gels are strengthened by the addition of the reinforcing agent. The transitions from a viscoclastic rubber to a plastic fluid and from a plastic fluid to a viscoelastic liquid are shifted to more elevated temperatures when silica is added to the triblock copolymer gel. (C) 2004 Elsevier Ltd. All rights reserved.
Radiotherapy Gel Dosimetry: Development and Application of Normoxic Polymer Gels
International Nuclear Information System (INIS)
In many radiotherapy applications, true three-dimensional dosimetry with good spatial resolution that can be achieved in a single measurement would be of great value. Polymer gel dosimetry fulfils many of the demands on such a system. In this study, methods to facilitate the implementation of gel dosimetry have been investigated. A new type of polymer gel, for which the response to absorbed dose is not negatively affected even if manufacturing is undertaken at normal levels of oxygen, called normoxic gel, was studied. The concept of percentage dose resolution was introduced to enable optimization of gel compositions for use in relative dosimetry applications. This concept was applied to demonstrate the effects of varying the gel composition on gel performance. Comparison between data obtained using magnetic resonance imaging and FT-Raman spectroscopy indicated that not all water protons attached to the polymer are accessible for exchange of magnetization with other proton groups. Dose response characteristics were investigated for a polymer gel containing the antioxidant tetrakis(hydroxymethyl)phosphonium. The transversal relaxation time (R2) versus dose response increased with increasing amounts of monomer, while no systematic dependence on antioxidant concentration was observed. The investigated normoxic gel exhibited a dependence on temperature during irradiation, leading to differences in absolute R2 as well as deviations in relative depth dose curves. It was suggin relative depth dose curves. It was suggested that the deviation in R2 can be attributed to structural differences in the polymer matrix, caused by varying polymerisation temperature. A linear relationship between absorbed dose and optical attenuation coefficient was observed, which demonstrates the potential for evaluation using light transmission measurements. Low-density gel was manufactured by mixing normal density normoxic gel with Styrofoam spheres. A linear correlation between R2 and dose was observed for doses up to 15 Gy. Possible dose response dependence on linear energy transfer (LET) was investigated using proton beam absorbed dose measurements. An increased LET with depth was closely followed by a decrease in relative detector sensitivity, indicating that the response of this type of gel detector is dependent on LET. No significant effects were observed for LET < 2.5 keV/mm, indicating that the detector response would not be altered in the range of LET values expected for photons or electrons in a clinical range of energies. The feasibility of using normoxic gel for intensity-modulated radiation therapy verification was investigated. Good agreement between treatment planning system calculations and measured data was obtained. For the planning target volume, the calculated and the measured mean relative dose was 96.8±2.5% (±1 SD) and 98.6±2.2%, respectively. The results indicated great potential for intensity-modulated radiation therapy verification using normoxic polymer gel
Rheology and structure of milk protein gels
van Vliet, T; Lakemond, C.M.M.; Visschers, R.W.
Recent studies on gel formation and rheology of milk gels are reviewed. A distinction is made between gels formed by aggregated casein, gels of `pure` whey proteins and gels in which both casein and whey proteins contribute to their properties. For casein' whey protein mixtures, it has been shown that both the fraction whey protein aggregated with the casein particles and whey protein aggregates dispersed in the continuous phase have a large impact on the structural and mechanical properties ...
Capillary fracture of soft gels
Bostwick, Joshua B
A liquid droplet resting on a soft gel substrate can deform that substrate to the point of material failure, whereby fractures develop on the gel surface that propagate outwards from the contact-line in a starburst pattern. In this paper, we characterize i) the initiation process in which the number of arms in the starburst is controlled by the ratio of surface tension contrast to the gel's elastic modulus and ii) the propagation dynamics showing that once fractures are initiated they propagate with a universal power law $L\\propto t^{3/4}$. We develop a model for crack initiation by treating the gel as a linear elastic solid and computing the deformations within the substrate from the liquid/solid wetting forces. The elastic solution shows that both the location and magnitude of the wetting forces are critical in providing a quantitative prediction for the number of fractures and, hence, an interpretation of the initiation of capillary fractures. This solution also reveals that the depth of the gel is an impo...
Sigman, Michael E.; Dindal, Amy B.
Described is a method for producing copolymerized sol-gel derived sorbent particles for the production of copolymerized sol-gel derived sorbent material. The method for producing copolymerized sol-gel derived sorbent particles comprises adding a basic solution to an aqueous metal alkoxide mixture for a pH.ltoreq.8 to hydrolyze the metal alkoxides. Then, allowing the mixture to react at room temperature for a precalculated period of time for the mixture to undergo an increased in viscosity to obtain a desired pore size and surface area. The copolymerized mixture is then added to an immiscible, nonpolar solvent that has been heated to a sufficient temperature wherein the copolymerized mixture forms a solid upon the addition. The solid is recovered from the mixture, and is ready for use in an active sampling trap or activated for use in a passive sampling trap.
Detection efficiency of scintillator gels
International Nuclear Information System (INIS)
A study was performed to determine whether the increased counting efficiency of gel scintillants (containing dioxan, PPO, dimethyl POPOP and naphthalene) with the addition of increasing amounts of silica could be due to increased fluorescence from PPO resulting from the increasing viscosity. This was tested by studying a series of gel scintillants of the same composition but containing no silica; an increasing viscosity was obtained by adding different quantities of liquid HP55 (hydroxypropyl-methyl-phthalate cellulose). The overall results with the scintillants containing HP showed a decreased fluorescence from PPO with increasing viscosity. However this was a result of two opposing mechanisms, i.e. an increased fluorescence from PPO due to increased viscosity and a direct quenching effect of HP55, the latter effect being predominant. The importance of the viscosity was thus confirmed, raised values leading to increased fluorescence from PPO and thus increased scintillation counting efficiency. A further study was made of other gel scintillants containing silica. (UK)
Screening effect on nanostructure of charged gel
DEFF Research Database (Denmark)
Sugiyama, M; Annaka, M
Charge screening effects on nanostructures of N-isopropylacrylamide-sodium acrylate (NIPA-SA) and -acrylic acid (NIPA-AAc) gels are investigated with small-angle neutron scattering. The NIPA-SA and NIPA-AAc gels with low water content exhibit microphase separations with different dimensions. The dehydrated NIPA-SA gel also makes the microphase separation but the dehydrated NIPA-AAc gel does not. These results indicate that ionic circumstance around charged bases strongly affects the nanostructures both of the dehydrated gel and the gel with low water content. (C) 2004 Elsevier B. V. All rights reserved.
Heterogeneous diffusion in a reversible gel
Hurtado, P I; Kob, W; Hurtado, Pablo I.; Berthier, Ludovic; Kob, Walter
We introduce a microscopically realistic model of a physical gel and use computer simulations to study its static and dynamic properties at thermal equilibrium. The phase diagram comprises a sol phase, a coexistence region ending at a critical point, a gelation line determined by geometric percolation, and an equilibrium gel phase unrelated to phase separation. The global structure of the gel is homogeneous, but the stress is supported by a fractal network. The gel dynamics is highly heterogeneous and we propose a theoretical model to quantitatively describe dynamic heterogeneity in gels. We elucidate several differences between the dynamics of gels and that of glass-formers.
Surface grafted chitosan gels. Part II. Gel formation and characterization
DEFF Research Database (Denmark)
Liu, Chao; Thormann, Esben
Responsive biomaterial hydrogels attract significant attention due to their biocompatibility and degradability. In order to make chitosan based gels, we first graft one layer of chitosan to silica, and then build a chitosan/poly(acrylic acid) multilayer using the layer-by-layer approach. After cross-linking the chitosan present in the polyelectrolyte multilayer, poly(acrylic acid) is partly removed by exposing the multilayer structure to a concentrated carbonate buffer solution at a high pH, leaving a surface-grafted cross-linked gel. Chemical cross-linking enhances the gel stability against detachment and decomposition. The chemical reaction between gluteraldehyde, the cross-linking agent, and chitosan was followed in situ using total internal reflection Raman (TIRR) spectroscopy, which provided a molecular insight into the complex reaction mechanism, as well as the means to quantify the cross-linking density. The amount of poly(acrylic acid) trapped inside the surface grafted films was found to decrease with decreasing cross-linking density, as confirmed in situ using TIRR, and ex situ by Fourier transform infrared (FTIR) measurements on dried films. The responsiveness of the chitosan-based gels with respect to pH changes was probed by quartz crystal microbalance with dissipation (QCM-D) and TIRR. Highly cross-linked gels show a small and fully reversible behavior when the solution pH is switched between pH 2.7 and 5.7. In contrast, low cross-linked gels are more responsive to pH changes, but the response is fully reversible only after the first exposure to the acidic solution, once an internal restructuring of the gel has taken place. Two distinct pKa's for both chitosan and poly(acrylic acid), were determined for the cross-linked structure using TIRR. They are associated with populations of chargeable groups displaying either a bulk like dissociation behavior or forming ionic complexes inside the hydrogel film. © 2014 American Chemical Society.
News concerning gel polymer electrolytes.
Czech Academy of Sciences Publication Activity Database
Sedla?íková, M.; Vondrák, Ji?í; Macalík, M.
Brno : University of technology Brno, 2009, s. 46-48. ISBN 978-80-214-3943-6. [International Conference Advanced Batteries, Accumulators and Fuel Cells /10./. Brno (CZ), 30.08.2009-02.10.2009] Institutional research plan: CEZ:AV0Z40320502 Keywords : gel polymer electrolytes Subject RIV: CG - Electrochemistry
Yield stress determination of a physical gel
DEFF Research Database (Denmark)
Hvidt, SŘren
Pluronic F127 solutions form gels in water with high elastic moduli. Pluronic gels can, however, only withstand small deformations and stresses. Different steady shear and oscillatory methods traditionally used to determine yield stress values are compared. The results show that the yield stresses values of these gels depend on test type and measurement time, and no absolute yield stress value can be determined for these physical gels.
Heterogeneous diffusion in a reversible gel
Hurtado, Pablo I.; Berthier, Ludovic; Kob, Walter
We introduce a microscopically realistic model of a physical gel and use computer simulations to study its static and dynamic properties at thermal equilibrium. The phase diagram comprises a sol phase, a coexistence region ending at a critical point, a gelation line determined by geometric percolation, and an equilibrium gel phase unrelated to phase separation. The global structure of the gel is homogeneous, but the stress is supported by a fractal network. The gel dynamics ...
Diffusion of potassium chromate in Agar gel
International Nuclear Information System (INIS)
Tracer and self-diffusion coefficients for potassium chromate labelled with 51Cr are determined in agar gel medium at different temperatures and the activation energies for the two processes are determined. The role of the obstruction effect on the self-diffusion coefficient is examined. The marked discrepancy observed between the experimentally determined formation factor and that predicted from the theory, whether on the basis of needle or spherical shape for the gel, suggests that apart from gel structure and known obstruction effect due to the gel matrix, other factors as specific binding between ions and gel matrix and electrostatic effects appear to influence the diffusion of ions. (orig.)
Symmetries and Elasticity of Nematic Gels
Lubenskii, T C; Radzihovsky, L R; Xing, X; Mukhopadhyay, Ranjan; Radzihovsky, Leo; Xing, Xiangjun
A nematic liquid-crystal gel is a macroscopically homogeneous elastic medium with the rotational symmetry of a nematic liquid crystal. In this paper, we develop a general approach to the study of these gels that incorporates all underlying symmetries. After reviewing traditional elasticity and clarifying the role of broken rotational symmetries in both the reference space of points in the undistorted medium and the target space into which these points are mapped, we explore the unusual properties of nematic gels from a number of perspectives. We show how symmetries of nematic gels formed via spontaneous symmetry breaking from an isotropic gel enforce soft elastic response characterized by the vanishing of a shear modulus and the vanishing of stress up to a critical value of strain along certain directions. We also study the phase transition from isotropic to nematic gels. In addition to being fully consistent with approaches to nematic gels based on rubber elasticity, our description has the important advanta...
Consolidation of Inorganic Precipitated Silica Gel
Directory of Open Access Journals (Sweden)
Matthias Kind
Full Text Available Colloidal gels are possible intermediates in the generation of highly porous particle systems. In the production process the gels are fragmented after their formation. These gel fragments compact to particles whose application-technological properties are determined by their size and porosity. In the case of precipitated silica gels, this consolidation process depends on temperature and pH, among other parameters. It is shown that these dependencies can be characterized by oedometer measurements. Originally, the oedometer test (one-dimensional compression test stemmed from soil mechanics. It has proven to be an interesting novel examination method for gels. Quantitative data of the time-dependent shrinkage of gel samples can be obtained. The consolidation of the gels shows a characteristic dependence on the above parameters.
Gel transitions in colloidal suspensions
Bergenholtz, Johan; Fuchs, Matthias
The idealized mode-coupling theory (MCT) is applied to colloidal systems interacting via short-range attractive interactions of Yukawa form. At low temperatures, MCT predicts a slowing down of the local dynamics and ergodicity-breaking transitions. The non-ergodicity transitions share many features with the colloidal gel transition, and are proposed to be the source of gelation in colloidal systems. Previous calculations of the phase diagram are complemented with additional data for shorter r...
Schmidt, Helmut K.
The synthesis of ceramic raw materials has become an important factor in ceramic technologies. The increasing demands to the performance of ceramic compounds has caused increased activities for the preparation of tailor-made raw materials. Amongst a variety of new syntheses like flame pyrolysis, reactive spray drying, plasma or laser assisted techniques, the sol-gel process plays an important and increasing role. The process describes the building up of an inorganic (in general an oxide) netw...
Evaluation of standard reagents for radial-immunodiffusion assays. In vitro control of rabies vaccines / Avaliaçăo de reativos padrőes para provas de Imunodifusăo Radial. Controle in vitro de vacinas antirrábicas
Scientific Electronic Library Online (English)
Graciela S., MICELI; Jorge, TORROBA; Walter, TORRES; Jorge, ESTEVES MADERO; Ana Maria, DÍAZ.
Full Text Available A prova de Imunodifusăo Radial (IDR) é um método in vitro conveniente para determinar a concentraçăo de antígenos no produto final como um todo, de vacinas anti-rábicas para uso veterinário. Os reativos padrőes candidatos para uso na prova IDR, proposta para o controle de processo de vacinas de cult [...] ivo celular, elaboradas na América Latina e Caribe, foram produzidos e padronizados no Instituto Panamericano de Proteçăo de Alimentos e Zoonoses (INPPAZ). A validaçăo dos padrőes e o controle de qualidade de 28 lotes de vacinas anti-rábicas, de diferentes procedęncias, foram realizados na Faculdade de Cięncias Veterinárias da Universidade de La Plata, Argentina (UNLP). Todas as vacinas foram elaboradas com virus rábico cepa Pasteur (PV) em células BHK e sua atividade foi determinada através de provas in vivo (NIH) e in vitro (IDR). Os resultados dos reativos, candidatos para as provas de padronizaçăo, demonstraram estabilidade, sensibilidade e reprodutibilidade. Por análise de variância e de regressăo foi estimada a potęncia relativa de 1.2 entre as vacinas problemas e a vacina de referęncia. Os resultados deste estudo de validaçăo indicam que o INPPAZ, está em condiçőes de elaborar e distribuir os reativos padrőes acima mencionados e apoiar a adoçăo da técnica de IDR (sensível, rápida, econômica) pelos laboratórios de produçăo de vacinas anti-rábicas da América Latina e Caribe. Abstract in english The RID assay is one of the in vitro methods used for in-process control in the production of rabies vaccines for veterinary use. It has been shown to be very useful for determining antigen concentration in the final bulk product. The work presented in this paper, including the production and standa [...] rdization of candidate standard reagents for use in the Radial Immunodiffusion Assay (RID) was carried out at the Pan American Institute for Food Protection and Zoonoses (INPPAZ/PAHO/WHO). The study was completed with the cooperation of the Faculty of Veterinary Sciences, National University of La Plata (NULP), Argentina, where the validation of the proposed standards and the quality control of samples from 28 different batches of rabies vaccines produced with Pasteur strain rabies virus (PV) in BHK cells were performed. The activity of the vaccines was determined by in vivo (NIH) and in vitro (RID)assays. The results of the candidate reagents for the reagent standardization tests showed stability, sensitivity and reproducibility. The Relative Potency the 1.2 between the problem vaccines and the reference vaccine was estimated by variance and regression analysis. The results of our validation study show that the INPPAZ (PAHO/WHO) is capable of producing and distributing the above-mentioned standard reagents, as well as of providing support for the incorporation of the RID technique (sensitive, rapid and inexpensive) to the laboratories that manufacture rabies vaccines in Latin America and the Caribbean.
Evaluation of standard reagents for radial-immunodiffusion assays. In vitro control of rabies vaccines Avaliaçăo de reativos padrőes para provas de Imunodifusăo Radial. Controle in vitro de vacinas antirrábicas
Directory of Open Access Journals (Sweden)
Graciela S. MICELI
Full Text Available The RID assay is one of the in vitro methods used for in-process control in the production of rabies vaccines for veterinary use. It has been shown to be very useful for determining antigen concentration in the final bulk product. The work presented in this paper, including the production and standardization of candidate standard reagents for use in the Radial Immunodiffusion Assay (RID was carried out at the Pan American Institute for Food Protection and Zoonoses (INPPAZ/PAHO/WHO. The study was completed with the cooperation of the Faculty of Veterinary Sciences, National University of La Plata (NULP, Argentina, where the validation of the proposed standards and the quality control of samples from 28 different batches of rabies vaccines produced with Pasteur strain rabies virus (PV in BHK cells were performed. The activity of the vaccines was determined by in vivo (NIH and in vitro (RIDassays. The results of the candidate reagents for the reagent standardization tests showed stability, sensitivity and reproducibility. The Relative Potency the 1.2 between the problem vaccines and the reference vaccine was estimated by variance and regression analysis. The results of our validation study show that the INPPAZ (PAHO/WHO is capable of producing and distributing the above-mentioned standard reagents, as well as of providing support for the incorporation of the RID technique (sensitive, rapid and inexpensive to the laboratories that manufacture rabies vaccines in Latin America and the Caribbean.A prova de Imunodifusăo Radial (IDR é um método in vitro conveniente para determinar a concentraçăo de antígenos no produto final como um todo, de vacinas anti-rábicas para uso veterinário. Os reativos padrőes candidatos para uso na prova IDR, proposta para o controle de processo de vacinas de cultivo celular, elaboradas na América Latina e Caribe, foram produzidos e padronizados no Instituto Panamericano de Proteçăo de Alimentos e Zoonoses (INPPAZ. A validaçăo dos padrőes e o controle de qualidade de 28 lotes de vacinas anti-rábicas, de diferentes procedęncias, foram realizados na Faculdade de Cięncias Veterinárias da Universidade de La Plata, Argentina (UNLP. Todas as vacinas foram elaboradas com virus rábico cepa Pasteur (PV em células BHK e sua atividade foi determinada através de provas in vivo (NIH e in vitro (IDR. Os resultados dos reativos, candidatos para as provas de padronizaçăo, demonstraram estabilidade, sensibilidade e reprodutibilidade. Por análise de variância e de regressăo foi estimada a potęncia relativa de 1.2 entre as vacinas problemas e a vacina de referęncia. Os resultados deste estudo de validaçăo indicam que o INPPAZ, está em condiçőes de elaborar e distribuir os reativos padrőes acima mencionados e apoiar a adoçăo da técnica de IDR (sensível, rápida, econômica pelos laboratórios de produçăo de vacinas anti-rábicas da América Latina e Caribe.
Counting efficiency of scintillating gels
International Nuclear Information System (INIS)
Scintillating gels that are suitable for the counting of insoluble radioact+ve samples, sometimes exhibit in addition a higher scintillation yield than the corresponding liquid scintillators. This property, observable when silica is added into dioxane liquid scintillators, is inherent in some primary solutes (PPO, PBD, butyl-PBD) while not obvious for others (CPO, PFD, BPO, ?NPO). Quenching properties of chlorinated compounds (CHCl3, CCl4) and energy transfer mechanisms are not changed by silica addition. On the other hand, PPO, PBD and butyl-PBD fluorescence quantum yields are markedly increased under these conditions, probably because of the higher viscosity of the samples. Another scintillating gel was prepared by the addition of HP55 (hydroxy propyl methyl cellulose phthalate) into PPO-dioxane liquid scintillator; its scintillation yield is reduced without any change of transfer mechanisms and at the same time PPO fluorescence quantum yield is diminished. A static quenching process by HP55 is likely to occur, which screens the viscosity effect noticed in the presence of Cab-O-Sil. Thus, PPO, PBD and butyl-PBD seem to be the most efficient primary solutes among those studied since they provide gel scintillator giving improved counting efficiency compared to that of liquid scintillator. (author)
Metal-silica sol-gel materials
Stiegman, Albert E. (Inventor)
The present invention relates to a single phase metal-silica sol-gel glass formed by the co-condensation of a transition metal with silicon atoms where the metal atoms are uniformly distributed within the sol-gel glass as individual metal centers. Any transition metal may be used in the sol-gel glasses. The present invention also relates to sensor materials where the sensor material is formed using the single phase metal-silica sol-gel glasses. The sensor materials may be in the form of a thin film or may be attached to an optical fiber. The present invention also relates to a method of sensing chemicals using the chemical sensors by monitoring the chromatic change of the metal-silica sol-gel glass when the chemical binds to the sensor. The present invention also relates to oxidation catalysts where a metal-silica sol-gel glass catalyzes the reaction. The present invention also relates to a method of performing oxidation reactions using the metal-silica sol-gel glasses. The present invention also relates to organopolymer metal-silica sol-gel composites where the pores of the metal-silica sol-gel glasses are filled with an organic polymer polymerized by the sol-gel glass.
Rheological characterization of Poloxamer 407 nimesulide gels
Directory of Open Access Journals (Sweden)
M. N. Freitas
Full Text Available The thermal gelling property of Poloxamer 407- nimesulide gels was characterized by rheological studies. Nimesulide, a local anti-inflammatory and anesthetic drug used for the treatment of acute and chronic pain, has a short duration of action and a long-acting single-dose injection would be of clinical importance. Thus a poloxamer 407 gel applied intramuscularly could prolong the release and action of nimesulide. In this study, aqueous gels with nimesulide, containing three different concentrations of Poloxamer 407, were prepared. Viscosity measurements were performed by rheologial studies to obtain the optimal sol-gel transition temperature . Poloxamer 407 gels are pseudoplastic and viscoelastic materials, which have an elastic modulus (G', characteristic of the solid, and a viscous modulus (G'', characteristic of the liquid material. Moreover, being pseudoplastic gels, when they are deformed by shearing, their viscosity decreases. Increase of the polymer concentration increased the viscosity of the gels, which could affect the releasing process of nimesulide. Furthermore, the presence of nimesulide led to a lowering of the sol-gel transition temperature. Keywords: Poloxamer 407 gels; nimesulide; rheological characterization; viscosity; sol-gel transition temperature.
Diagnosis of peste des petits ruminants infection in small ruminants through in-house developed Indirect ELISA: Practical considerations
Directory of Open Access Journals (Sweden)
K. K. Sharma
Full Text Available Aim: The work was conducted to diagnose peste des petits ruminants (PPR outbreak through an in house developed indirect ELISA (thereafter referred as iELISA its comparison with other available diagnostic tests and description of practical considerations in its development, utility and limitations. Materials and Methods: An outbreak resembled to PPR occurred in two different places of southern Gujarat viz. Vapi and Navsari, affecting 622 animals, including both goat (n = 476 and sheep (n = 146. Animals displayed the typical signs of PPR at Vapi; however diarrhea was the inconsistent feature in animals of Navsari. The affection caused morbidity of 100% and mortality were 73.68% (n = 392/532 and 56.67% (n = 51/90 in Vapi and Navsari outbreaks, respectively. Relevant ante mortem and post mortem samples were collected from representative animals. At the outset of the epidemic no kit was available with us, so agar gel immunodiffusion (AGID was carried out and a commercial ELISA (cELISA kit was ordered for making diagnosis through antibody demonstration. Meanwhile, an iELISA was developed in house using PPR vaccine as antigen and protein G conjugated HRPO antibody as detector. Histopathology and results of sandwich ELISA were also used to diagnose PPR virus (PPRV in the outbreak. Results: The iELISA developed had detected PPRV antibodies in 22/24 samples (91.66%. Significant difference was observed in disease sensitivity pattern of two species by Chi-square test. While AGID failed to detect antibodies in any sample. Results were reconfirmed by comparing with commercially available cELISA kit. Conclusion: PPR is an economically important disease and for the rapid diagnosis of PPR the in house developed antibody capture iELISA can be a suitable cost effective alternative.
Epidemiologia da infecçăo pelo vírus da Leucose Enzoótica Bovina (LEB) / Epidemiology of Enzootic Bovine Leukemia (BLV) virus infection
Scientific Electronic Library Online (English)
José Wilton, Pinheiro Junior; Maria Evódia de, Souza; Wagnner José Nascimento, Porto; Nair Silva Cavalcanti, Lira; Rinaldo Aparecido, Mota.
Full Text Available Objetivou-se com este trabalho investigar a presença de anticorpos anti-vírus da leucose enzoótica além de identificar a associaçăo entre variáveis de manejo e soropositividade para essa infecçăo em bovinos no Estado de Alagoas, Brasil. Foram examinados 17 rebanhos, perfazendo um total de 341 animai [...] s, distribuídos em oito municípios. A pesquisa de anticorpos foi efetuada pela técnica de Imunodifusăo em Gel de Ágar (IDGA), utilizando-se o antígeno constituído por lipopolissacarídeos e proteínas do vírus da leucose bovina. Das 341 amostras analisadas, 95 (27,8%) foram positivas e o número de focos constatados foi de 12 (70,6%). Foram observadas diferenças significativas para as variáveis: assistęncia técnica (p Abstract in english The purpose of this study was to investigate the presence of anti-enzootic leucosis virus antibodies and also to identify the association between seropositivity and management variables for this infection in cattle in the State of Alagoas, Brazil. A total of 17 herds were examined, totaling 341 anim [...] als, distributed in eight counties. The antibody detection was performed by the technique of agar gel immunodiffusion (AGID), using the antigen constituted of lipids and proteins from bovine leukosis virus. From the 341 samples analyzed, 95 (27.8%) were positive and the number of outbreaks was 12 (70.6%). Significant differences were observed for the variables: technical assistance (p
Prevalence of bluetongue virus antibodies in sheep from Distrito Federal, BrazilPrevalęncia de anticorpos contra o vírus da língua azul em ovinos do Distrito Federal
Directory of Open Access Journals (Sweden)
Aurora Maria Guimarăes Gouveia
Full Text Available The aims of the present study were to determine the prevalence of bluetongue virus antibodies in sheep from Distrito Federal. Sera from 606 sheep of 18 herds were submitted to the agar-gel immunodiffusion for bluetongue virus antibodies. The prevalences of bluetongue infection found in Distrito Federal were 100% (CI 95%: 84.67 to 100.00 for flocks and 52.37% (389/606 (CI 95%: 35.76 to 68.98 for animals. Thus, data from the present study showed that infection by bluetongue virus is highly widespread in sheep flocks in the Distrito Federal, which intensifies the need for assessments on the impact of this disease in Brazil. O objetivo deste trabalho foi estimar a prevalęncia de anticorpos contra o vírus da língua azul (BTV em rebanhos ovinos do Distrito Federal. Soros de 606 ovinos, pertencentes a 18 propriedades, foram analisados pela técnica de imunodifusăo em ágar gel (AGID, para pesquisa de anticorpos contra o BTV. As prevalęncias de rebanhos e de animais infectados pelo vírus da língua azul no Distrito Federal foram respectivamente de 100% (IC 95%: 84,67% a 100% e de 52,37% (389/606 (IC 95%: 35,76% a 68,98%. Assim, o presente estudo permite concluir que o vírus da língua azul está amplamente disseminada no rebanho ovino do Distrito Federal.
Soroepidemiologia da leucemia bovina (LB) em bovinos curraleiros dos estados de Goiás e Tocantins, Brasil / Seroepidemiology of bovine leukaemia (LB) in curraleiro cattle breed from Goiás and Tocantins states
Scientific Electronic Library Online (English)
Raquel Soares, Juliano; Maria Clorinda Soares, Fioravanti; Wilia Marta Elsner Diederichsen de, Brito; Urbano Gomes Pinto de, Abreu; Saura Nayane de, Souza.
Full Text Available Com o objetivo de verificar a ocorręncia da leucose enzoótica (LB) em bovinos Curraleiros, foram amostrados soros sanguíneos de um total de 1051 animais pertencentes a 11 rebanhos localizados nos Estados de Goiás e 12 em Tocantins. O diagnóstico sorológico de LB foi realizado pelo método de imunodif [...] usăo em gel de ágar (IDGA). A taxa total de sororeagentes foi 21,1% (222/1051). Em Tocantins foram encontrados 27,8% (136/489) de sororreagentes, número significativamente maior que em Goiás, onde foram encontrados 15,3% (86/562). A sororreatividade foi maior em fęmeas que em machos, 23,3% (198/852) e 11,8% (23/195), respectivamente, e em animais com idade superior a 48 meses. Abstract in english Aiming to verify bovine leukaemia (BL) occurrence in Curraleiro cattle breed, sera of 1051 animals were sampled from Goias (n=11) and Tocantins (n=12) states. BL serological diagnosis was performed by agar gel immunodiffusion method (AGID). The total occurrence rate was 21.1% (222/1051). In Tocantin [...] s it was 27.8% (136/489) occurrence was observed, higher value than in Goias, where 15.3% (86/562) occurrence was found. The serum reactivity was higher in females than in males, 23.3% (198/852) and 11.8% (23/195), respectively, and in animals older than 48 months old.
Active Gel Model of Amoeboid Cell Motility
Callan-Jones, A C
We develop a model of amoeboid cell motility based on active gel theory. Modeling the motile apparatus of a eukaryotic cell as a confined layer of finite length of poroelastic active gel permeated by a solvent, we first show that, due to active stress and gel turnover, an initially static and homogeneous layer can undergo a contractile-type instability to a polarized moving state in which the rear is enriched in gel polymer. This agrees qualitatively with motile cells containing an actomyosin-rich uropod at their rear. We find that the gel layer settles into a steadily moving, inhomogeneous state at long times, sustained by a balance between contractility and filament turnover. In addition, our model predicts an optimal value of the gel-susbstrate adhesion leading to maximum layer speed, in agreement with cell motility assays. The model may be relevant to motility of cells translocating in complex, confining environments that can be mimicked experimentally by cell migration through microchannels.
Macedo, Marcelo A.; Aegerter, Michel A.
All solid state electrochromic devices have potential applications in architectural and automotive fields to regulate the transmission and reflection of radiant energy. We present the optical and electrochemical characteristics of two solid state windows having the configuration glass/ITO/TiO2-CeO2/TiO2/TiO2-CeO2/ITO/glass and glass/ITO/WOa/TiO2/TiO2-CeO2/ITO/glass where the three internal layers have been prepared by sol gel methods. The preparation of the individual sols and some physical p...
Motility initiation in active gels
Recho, Pierre; Truskinovsky, Lev
Motility initiation in crawling cells requires a symmetry breaking mechanism which transforms a symmetric state into a polarized state. Experiments on keratocytes suggest that polarization is triggered by increased contractility of motor proteins. In this paper we argue that contraction can be responsible not only for the symmetry breaking transition but also for the incipient translocation of the segment of an active gel mimicking the crawling cell. Our model suggests that when the contractility increases sufficiently far beyond the motility initiation threshold, the cell can stop and re-symmetrizes. The proposed theory reproduces the motility initiation pattern in fish keratocytes and the behavior of keratocytes prior to cell division.
Buckling of paramagnetic chains in soft gels
Huang, Shilin; Pessot, Giorgio; Cremer, Peet; Weeber, Rudolf; Holm, Christian; Nowak, Johannes; Odenbach, Stefan; Menzel, Andreas M.; Auernhammer, Gu?nter K.
We study the magneto-elastic coupling behavior of paramagnetic chains in soft polymer gels exposed to external magnetic fields. To this end, a laser scanning confocal microscope is used to observe the morphology of the paramagnetic chains together with the deformation field of the surrounding gel network. The paramagnetic chains in soft polymer gels show rich morphological shape changes under oblique magnetic fields, in particular a pronounced buckling deformation. The detai...
Computer Analysis of Two-Dimensional Gels
Goldfarb, Marcia
This work identifies statistical algorithms which need to be included in analysis of two-dimensional gels for accurate determination of differential changes. Two-dimensional electrophoresis is a powerful tool for determining differential protein expression in complex mixtures, but the methodology, to date, is not producing expected results due to the degree of gel variability. The new DIGE procedure, comparing two samples in the same gel, does eliminate some of the variability introduced with...
Crystal structure of thermally reversible maltodextrin gels
International Nuclear Information System (INIS)
Aqueous solutions of starch solidify at room temperature to form thermally irreversible gels. These gels exhibit the wide angle X-ray pattern of B-starch. In thermally reversible gels of a special digestion product of starch the B-pattern of starch is also observed. The property of thermal reversibility therefore is not due to amorphous or different crystalline structures, but is a consequence of smaller macromolecules. (author)
Polymer gel electrolytes for lithium batteries
International Nuclear Information System (INIS)
The data on the most promising polymer gel electrolytes for lithium batteries published in the past decade are surveyed and described systematically. Gel electrolytes with matrices of polyethylene oxide, poly(vinylidene fluoride) and its copolymer with hexafluoropropylene, poly(methyl methacrylate), polyacrylonitrile, poly(vinyl chloride) and polyacrylates are discussed. A special section is devoted to gel electrolytes with ionic liquids as the solvents. The bibliography includes 160 references.
Brillouin light-scattering from polymer gels
Ng, S.; Li, Y.
The experimental results of th Brillouin shift and width for poly(vinyl alcohol) and poly(vinyl chloride) gels as a function of gel network volume fraction have been analysed using the theory of Marqusee and Deutch for Brillouin light-scattering from polymer gels, incorporated with a new plausible assumption relating the speed of sound in the gel network with its volume fraction. It has been found that the essential features of the behaviour of th Brillouin shift and width are well described ...
Padronizaçăo do Elisa indireto e Western Blot para diagnóstico da artrite-encefalite caprina / Standardization of indirect Elisa and Western Blot for diagnosis of Caprine Arthritis-Encephalitis
Scientific Electronic Library Online (English)
A.S., Rodrigues; R.L.L., Brito; R.R., Pinheiro; R.P., Dias; S.M., Alves; T.S., Souza; K.C., Souza; D.A.A., Azevedo; A., Andrioli; D.C.T., Magalhăes; M.F.S., Teixeira.
Full Text Available A artrite-encefalite caprina (CAE) é diagnosticada rotineiramente pela técnica de imunodifusăo em gel de agarose (IDGA), que é considerada pouco sensível. Objetivou-se com este estudo padronizar testes de Elisa-i e Western Blot (WB) para diagnóstico precoce de anticorpos em caprinos contra CAEV e co [...] mparar os resultados obtidos nesses testes com a prova de IDGA. Para a padronizaçăo dos testes Elisa-i e WB, utilizaram-se diferentes concentraçőes e diluiçőes de antígeno, soros e conjugado. No Elisa-i, adotaram-se microplacas rígidas com 96 poços, sendo a combinaçăo de concentraçăo de 0,5µg/poço de antígeno e diluiçőes de 1:100 de soro e 1:1500 de conjugado a que apresentou melhor resultado. No WB foram utilizadas membranas de nitrocelulose, definindo-se as diluiçőes de 1:50 de soro e 1:15000 de conjugado. Para avaliar o desempenho das técnicas, 222 amostras de soro caprino foram testadas e os dados obtidos foram comparados com o IDGA. A sensibilidade e a especificidade do Elisa-i/IDGA, WB/IDGA e WB/Elisa-i foram de 70% e 91%, 100% e 72,6%, 84,6% e 76,5%, concomitantemente. O índice Kappa desses testes foi de 0,35, 0,2 e 0,36, respectivamente. As técnicas de Elisa-i e WB apresentaram-se mais sensíveis que a IDGA, podendo ser utilizadas como ferramentas para o diagnóstico precoce da CAE. Abstract in english Caprine arthritis-encephalitis (CAE) is routinely diagnosed with the Agarose Gel Immunodiffusion (AGID) technique, which is considered to have low sensitivity. The objective of this study was to standardize testing i-Elisa and Western Blot for early detection of antibodies against CAEV in goats and [...] compare the results obtained in these tests with proof of AGID. For standardization of i-Elisa and WB, different concentrations and dilutions of antigen, sera and conjugate were used. In the i-Elisa, rigid microplate with 96 wells was adopted, and the combination that showed the best result was a concentration of 0.5µg/ well of antigen and dilutions of the serum of 1:100 and conjugate of 1:1500. In the WB nitrocellulose membranes were used, and the dilutions of the serum were defined at 1:50 and conjugate at 1:15000. To evaluate the performance of the techniques, 222 goat serum samples were tested and the data were compared with the AGID. The sensitivity and specificity of Elisa-i/IDGA, WB/AGID and WB/Elisa-i were 70% and 91%, 100% and 72.6%, 84.6% and 76.5%, concomitantly. The Kappa index of these tests was 0.35, 0.2 and 0.36, respectively. The i-Elisa and WB techniques were more sensitive than the AGID and can be used as tools for early diagnosis of CAE.
Gel-eletroforese no diagnóstico da varíola Gel-electrophoresis in the smallpox diagnosis
Directory of Open Access Journals (Sweden)
Julio A. Mesquita
Full Text Available O emprego de gel-eletroforese no diagnóstico da varíola, demonstrou ser ao menos trinta vezes (30X mais sensível que o teste de agar-gel, nas condiçőes descritas (tabela I. Doze (12 espécimes, cujos testes convencionais de inoculaçăo em ovos embrionados e de agar-gel resultaram positivos, foram testados em suas diluiçőes originais congeladas por mais de um ano, sendo seis deles revelados por gel-eletroforese enquanto nenhum o foi por agar-gel (tabela II. Trinta e tręs (33 amostras isoladas no laboratório, foram testadas com material colhido de membrana cório-alantóica da primeira inoculaçăo para o diagnóstico, conservado em glicerina 50%, resultando 15 positivas em gel-eletroforese e apenas 3 em agar-gel (tabela II. Os últimos 60 espécimes recebidos para diagnóstico, através a Campanha de Erradicaçăo da Varíola, também resultaram negativos em gel-eletroforese, que năo mostrou falsos-positivos nas condiçőes descritas.The test of gel-electrophoresis applied to the pox virus group showed to be at least thirth times (30X more sensitive than agar-gel test on the described conditions (Table I. Twelve specimens, which were positives form Smallpox in the conventional tests of egg inoculation and agar-gel difusion test, have been screened in their original dilutions frozen for more than 1 year and six of them were still detectable by gel-eletrophoresis, while by agar-gel test any of them was positive (Table II. Thirty three Smallpox isolates have been tested with material from first egg inoculation (chorioallantoic membranes which have been stored in glycerin 50%, at - 15şC. Fifteen of them were still positive by gel-electrophoresis and only 3 by agar-gel (Table II. The last 60 specimens received for diagnosis from Smallpox Erradication Campaign (CEV, were negatives by both tests. The gel-electrophoresis, did not show false-positives on described conditions.
Stacking gels: A method for maximising output for pulsed-field gel electrophoresis
Directory of Open Access Journals (Sweden)
Heng See
Full Text Available Pulsed field gel electrophoresis (PFGE, the gold standard of molecular typing methods, has a major disadvantage of an unusually long electrophoretic time. From the original protocol of 6 days, it was modified to 3 days and subsequently to a single day. We describe the procedure of stacking five to six gels one on top of another in order to increase and maximize the output in a shorter time without compromising the resolution and reproducibility. All the variables that affect pulsed field gels during electrophoresis were taken into consideration. We firstly optimized the parameters to be used and secondly determined whether stacking of five to six gels had any effect on the molecular separation during electrophoresis in comparison with a single gel run. DNA preparation, restriction, electrophoresis, staining and gel documentation was carried out based on previously published methods. Gels were analysed using BioNumerics and dice coefficient and unweighted pair group methods were used to generate dendrograms based on 1.5% tolerance values. Identical band profiles and band resolution-separation were seen in the PFGE patterns with single gel and multiple stacking gels. Cluster analysis further strengthened the fact that results from stacking gels were reproducible and comparable with a single gel run. This method of stacking gels saves time and maximizes the output at the same time. The run time for a single gel was about 28 hours, but with six stacked gels the run time was 54 hours compared with 28 x 6 = 168 hours if they were run separately as single gels thus saving time of 67.86%. Beside the big factor of saving time, stacking gels save resources (electricity, reagents, water, chemicals and working time by increasing the sample throughput in a shorter time without compromising on quality of data. But optimization of working parameters is vital depending on the PFGE system used.
Principles of Gel Permeation Chromatography
Principles of Gel Permeation Chromatography presents the principles of gel permeation chromatography (GPC) for students in introductory undergraduate courses of chemistry and biochemistry. These principles are presented in four sections: Introduction, Real Lab, Virtual Lab, and Microscopic Model. The Introduction and Real Lab sections present a brief view of the basic experimental apparatus typically used in laboratory GPC in order to provide a concrete connection of the real process of separation. The basic elements of column chromatography, emphasizing the stationary and mobile phases, are presented in the Introduction, followed by a sequence of pictures and texts describing major steps in GPC analysis in the Real Lab section. The Virtual Lab section is a simulator. Three samples are available for a virtual GPC experiment: sample 1, containing hemoglobin; sample 2, containing methylene blue; and sample 3, containing both methylene blue and hemoglobin. Each sample undergoes a virtual separation run, which is dynamically represented in three ways in the software: a virtual column, the collected fractions, and a virtual chromatogram. This threefold representation allows the simultaneous view of key aspects of the process to demonstrate the correlation between the experimental procedure and the resulting chromatogram.
The Principle of Polysaccharide Gels
Directory of Open Access Journals (Sweden)
Masakuni Tako
Full Text Available For several decades attention has been directed to natural polysaccharide gels and synthesized polymer gels. The structure-function relationships at molecular level in water of polysaccharides, ?-carrageenan, ?-carrageenan, agarose (agar, and gellan family of polysaccharides (gellan, welan, rhamsan, S-657, deacetylated rhamsan and native gellan gum, which are industrially useful polysaccharides extracted from family of red seaweeds and bacteria, in principle are discussed on the view point of rheological aspects. The polysaccharide molecules (0.1% - 1.0% play a dominant role in the center of the tetrahedral cavities occupied by water molecules (99.0% - 99.9%, and the arrangement is similar to a tetrahedral structure in a gelation process. The cage and hydrophobic effect play thermal dynamically dominant role in gelation process which gives lowest entropy to electrons of sugar residues. Though the chemical structure of these polysaccharides similar each other, their rheological (gelling characteristics are quite different. Many investigations about the gelling properties of the polysaccharides have been undertaken to elucidate the structure-function relationship, but no other researchers have established mechanism at the molecular level. There is consistency in our investigations. Thus, the rheological analysis is one of significant methods for understanding the structure-function relationship of polysaccharides in aqueous media. The discussion provides many important information not only in academic field, but also in industrial one, such as food, cosmetic, pharmaceutical, drug delivery and tissue industries, and biotechnology.
Radiological properties of normoxic polymer gel dosimeters
International Nuclear Information System (INIS)
The radiological properties of the normoxic polymer gel dosimeters MAGIC, MAGAS, and MAGAT [methacrylic and ascorbic acid in gelatin initiated by copper; methacrylic acid gelatine gel with ascorbic acid; and methacrylic acid gelatine and tetrakis (hydroxymethyl) phosphonium chloride, respectively] have been investigated. The radiological water equivalence was determined by comparing the polymer gel macroscopic photon and electron interaction cross sections over the energy range from 10 keV to 20 MeV and by Monte Carlo modeling of depth doses. Normoxic polymer gel dosimeters have a high gelatine and monomer concentration and therefore mass density (kg m-3) up to 3.8% higher than water. This results in differences between the cross-section ratios of the normoxic polymer gels and water of up to 3% for the attenuation, energy absorption, and collision stopping power coefficient ratios through the Compton dominant energy range. The mass cross-section ratios were within 2% of water except for the mass attenuation and energy absorption coefficients ratios, which showed differences with water of up to 6% for energies less than 100 keV. Monte Carlo modeling was undertaken for the polymer gel dosimeters to model the electron and photon transport resulting from a 6 MV photon beam. The absolute percentage differences between gel and water were within 1% and the relative percentage differences were within 3.5%. The results show that the MAGAT gel formulation is the mostthat the MAGAT gel formulation is the most radiological water equivalent of the normoxic polymer gel dosimeters investigated due to its lower mass density measurement compared with MAGAS and MAGIC gels
Effect of iron gel on dentin permeability
Scientific Electronic Library Online (English)
Sílvia Helena de Carvalho, Sales-Peres; Joăo Victor Donazan, Reinato; André de Carvalho, Sales-Peres; Juliane Avansini, Marsicano.
Full Text Available Este estudo objetivou avaliar in vitro o efeito do gel experimental contendo ferro na reduçăo da condutividade hidráulica na dentina. Trinta e seis discos de dentina humana de 1 mm de espessura, foram obtidos de terceiros molares extraídos divididos em 3 grupos de 10 espécimes cada. Os grupos foram [...] divididos nos seguintes grupos experimentais: F- flúor gel a 1,23%, pH 4,1; O- gel de oxalato de potássio a 3%, pH 4,1; I- gel de sulfato ferroso FeSO4 a 10 mmol/L, pH 4,1. Os géis foram aplicados na dentina sob as diferentes condiçőes: após o ácido fosfórico a 37% a antes do ácido cítrico a 6%. Os resultados foram analisados por ANOVA e teste de Tukey, com nível de significância de 5%. Todos os grupos (gel de flúor, oxalato de potássio e gel de ferro) năo apresentaram diferenças significativas entre si para todas as condiçőes testadas, exceto na presença da smear layer (p Abstract in english This study evaluated in vitro the effect of an experimental gel containing iron on the reduction of hydraulic conductance of dentin. Thirty-six 1-mm-thick dentin discs obtained from extracted human third molars were divided into 3 groups of 10 specimens each. The groups corresponded to the following [...] experimental materials: 1.23% acidulated phosphate fluoride gel, pH 4.1; 3% potassium oxalate gel, pH 4.1 (Oxa-Gel®); and iron sulfate gel (10 mmol/L FeSO4), pH 4.1. The gels were applied to dentin under the following conditions: after 37% phosphoric acid and before 6% citric acid. Data were analyzed statistically by ANOVA and Tukey's test at 5% significance level. There was no significant differences (p0.05) among the gels. This study suggests that the iron gel promoted reduction in dentin permeability comparable to that of the other agents and thus may be considered a good clinical alternative for the treatment of dentin hypersensitivity.
FTIR thermal analysis on organofunctionalized silica gel
Directory of Open Access Journals (Sweden)
Foschiera José L.
Full Text Available Silica gel modified with organic groups is widely used as a stationary phase for liquid chromatography. Grafting synthesis can be used to obtain stable modified silica gel surfaces. In this work, silica gel (10 nm of pore diameter and surface area of 320 m˛ g-1 was chemically modified with 3-chloropropyltrimethoxysilane or 3-aminopropyltrimethoxysilane and reacted with aniline, p-anisidine, benzylamine and 3-phenylpropylchloride in order to yield aromatic groups immobilized on the silica gel surface. Infrared spectroscopy was utilized for characterization of the aromatic groups grafted on the silica gel surface, using a quartz cell. The solids were heated at several temperatures in high vacuum and the infrared band areas of the organic groups were used to evaluate the thermal stability.
Chitosan: Gels and Interfacial Properties
Directory of Open Access Journals (Sweden)
Julie Nilsen-Nygaard
Full Text Available Chitosan is a unique biopolymer in the respect that it is abundant, cationic, low-toxic, non-immunogenic and biodegradable. The relative occurrence of the two monomeric building units (N-acetyl-glucosamine and d-glucosamine is crucial to whether chitosan is predominantly an ampholyte or predominantly a polyelectrolyte at acidic pH-values. The chemical composition is not only crucial to its surface activity properties, but also to whether and why chitosan can undergo a sol–gel transition. This review gives an overview of chitosan hydrogels and their biomedical applications, e.g., in tissue engineering and drug delivery, as well as the chitosan's surface activity and its role in emulsion formation, stabilization and destabilization. Previously unpublished original data where chitosan acts as an emulsifier and flocculant are presented and discussed, showing that highly-acetylated chitosans can act both as an emulsifier and as a flocculant.
21 CFR 872.1730 - Electrode gel for pulp testers.
... false Electrode gel for pulp testers. 872.1730 Section...CONTINUED) MEDICAL DEVICES DENTAL DEVICES Diagnostic Devices § 872.1730 Electrode gel for pulp testers. (a) Identification. An electrode gel for pulp testers is a device...
Radiation sensitive polymer gel dosimeters
International Nuclear Information System (INIS)
Full text: Radiation sensitive gels are studied for their potential to retain a permanent 3D dose distribution for applications in radiotherapy. Co-monomers dissolved in a tissue-equivalent hydrogel undergo a polymerization reaction upon absorption of ionizing radiation. The polymer formed influences the local spin-spin relaxation time (T2) of the dosimeter that can be determined using magnetic resonance imaging (MRI). The relationship between T2 and the absorbed dose was studied for different initial chemical compositions. The aim was to find a model linking the changes in T2 with absorbed dose to the initial composition of the dosimeter. It is believed this will help designing new gel dosimeters having desired properties to minimize the uncertainty in the determination of the dose distribution. 1H, 13C nuclear magnetic resonance spectroscopy and FT-Raman spectroscopy were used to quantify the amount of monomers still remaining after the absorption of a given dose of radiation. This data is used to model the changes of T2 as a function of the absorbed dose. A model of fast exchange of magnetization between three proton pools was used, where the fraction of protons (fxH ) in the xth pool is obtained from the chemical composition of the dosimeter and the apparent T2 of each pool is determined for a given composition. Initially, the protons are contained in two pools; a mobile (mob), which contd in two pools; a mobile (mob), which contains the water protons and the monomers protons, and a gelatin (gela) proton pool. The mobile pool is partially depleted as polymer is formed, the protons are transferred into the polymer (pol) pool. In the figure, the experimental data along with the calculated values are plotted for three different monomer concentrations, with the gelatin concentration fixed. The model is seen to provide a good fit to the experimental data
Sol-Gel Manufactured Energetic Materials
Simpson, Randall L. (Livermore, CA); Lee, Ronald S. (Livermore, CA); Tillotson, Thomas M. (Tracy, CA); Hrubesh, Lawrence W. (Pleasanton, CA); Swansiger, Rosalind W. (Livermore, CA); Fox, Glenn A. (Livermore, CA)
Sol-gel chemistry is used for the preparation of energetic materials (explosives, propellants and pyrotechnics) with improved homogeneity, and/or which can be cast to near-net shape, and/or made into precision molding powders. The sol-gel method is a synthetic chemical process where reactive monomers are mixed into a solution, polymerization occurs leading to a highly cross-linked three dimensional solid network resulting in a gel. The energetic materials can be incorporated during the formation of the solution or during the gel stage of the process. The composition, pore, and primary particle sizes, gel time, surface areas, and density may be tailored and controlled by the solution chemistry. The gel is then dried using supercritical extraction to produce a highly porous low density aerogel or by controlled slow evaporation to produce a xerogel. Applying stress during the extraction phase can result in high density materials. Thus, the sol-gel method can be used for precision detonator explosive manufacturing as well as producing precision explosives, propellants, and pyrotechnics, along with high power composite energetic materials.
Preparation and Characteristics of ADU gel Particles
International Nuclear Information System (INIS)
HTGR (High Temperature Gas Reactor) energy technology development has been spot-lighted for a clean hydrogen gas and electricity production for the countermeasures of supplying a massive energy production in the next decades because other energies such as solar heat, wind power, and tidal energy, can only produce a small amount of electricity or they are not as effective. Generally, the production of spherical UO2 kernels for a HTGR nuclear fuel can be carried out by wet chemical processes, a sol-gel process, based on a solidification of uranium liquid droplets as a raw material. Sol-gel process is a proper way to produce the UO2 kernel because of its advantages in a high quality of products, low heat treatment temperature, and an easy control of the components. However, there are only a few reports on the preparation of a spherical UO2 kernel by a sol-gel method. In this study, spherical ADU gel particle and UO3 particles via an UN(uranyl nitrate, UO2(NO3) solution as a raw material were prepared. And the characteristics of these liquid droplets and the ADU gel particle prepared with the sol-gel method were analyzed, and the heat treatment characteristics from the ADU gel to UO3 particle were analyzed by a Streoscope, TG/DTA, and X-ray
FTIR thermal analysis on organofunctionalized silica gel
Scientific Electronic Library Online (English)
José L., Foschiera; Tania M., Pizzolato; Edilson V., Benvenutti.
Full Text Available Sílica gel modificada com grupos orgânicos tem sido muito utilizada como fase estacionária para cromatografia líquida. Reaçőes de enxerto podem ser usadas na obtençăo de superfícies modificadas estáveis de sílica gel. Neste trabalho a sílica gel (10 nm de diâmetro de poro e 320 m˛ g-1 de área superf [...] icial) foi modificada quimicamente com 3-cloropropiltrimetoxisilano ou com 3-aminopropiltrimetoxisilano e posteriormente com anilina, p-anisidina, benzilamina e 3-fenilpropilcloreto a fim de se obter grupos aromáticos imobilizados na superfície de sílica gel. A espectroscopia no infravermelho foi utilizada para a caracterizaçăo dos grupos aromáticos enxertados, usando-se uma cela de quartzo. Os sólidos foram aquecidos a várias temperaturas em alto vácuo sendo que as áreas sob as bandas dos grupos orgânicos obtidas no infravermelho foram usadas para estimar a estabilidade térmica. Abstract in english Silica gel modified with organic groups is widely used as a stationary phase for liquid chromatography. Grafting synthesis can be used to obtain stable modified silica gel surfaces. In this work, silica gel (10 nm of pore diameter and surface area of 320 m˛ g-1) was chemically modified with 3-chloro [...] propyltrimethoxysilane or 3-aminopropyltrimethoxysilane and reacted with aniline, p-anisidine, benzylamine and 3-phenylpropylchloride in order to yield aromatic groups immobilized on the silica gel surface. Infrared spectroscopy was utilized for characterization of the aromatic groups grafted on the silica gel surface, using a quartz cell. The solids were heated at several temperatures in high vacuum and the infrared band areas of the organic groups were used to evaluate the thermal stability.
Energy dependence of Fricke-xylenol orange gel and gel based on Turnbull blue for low-energy photons
Šolc, Jaroslav; Sochor, Vladimír; Kozubíková, Petra
The paper describes the energy dependence of two types of radiochromic gels, a Fricke-xylenol orange gel (FX gel) and a gel based on Turnbull blue (TB gel), on low energy photons between 14 and 145 keV. Gel samples were irradiated at reference photon fields at the Czech Metrology Institute and evaluated by two independent optical methods. Measurements revealed that the response of the TB gel is independent on photon energy down to at least 14 keV photons, while the FX gel is energy dependent for photons below roughly 50 keV.
Yang, Quanzu
The fundamental goal of the present study was to develop an understanding of the mechanisms of dispersion, gelation, drying, interfacial bonding and densification of composite sol-gel (CSG) ceramics. The general applied objective was to fabricate high performance CSG ceramics and to produce novel, non-permeable, adherent CSG coatings on stainless steel substrates for high temperature corrosion and wear protection. The properties of the alumina sols and CSG were studied by measuring viscosity, conductivity, ionic strength, and pH of the sol. The dispersion and stability of ceramic particles in alumina sols were investigated by measuring particle size distributions, measuring zeta potentials, and calculating the interaction energy according to DLVO theory. The CSG technology has been developed to fabricate high performance engineering composite ceramics and coatings through dispersing ceramic fillers (alumina, zirconia, SiC) into alumina sols, gelcasting, drying, and pressureless sintering. A sintering model for CSG was developed and validated by experiment results. The model was then used successfully to predict sinterability and to optimize the processing technologies of CSG. The research results indicate that hydrated alumina sols can be used as a sintering and dispersion additive for alumina-based ceramics. The sol-gel matrix provides fast diffusion paths for mass transport during sintering CSG. Dispersion of alumina and SiC particles is substantially improved in alumina sols, as compared to pure water of similar acidity, e.g. the average agglomerate size is decreased by at least 50%. For alumina/alumina CSG ceramics sintered at 1400°C, the microhardness is 20 GPa and porosity is less than 1 vol%. The CSG composite with composition of 50vol%SiC-50vol%Al2O 3 has been sintered successfully to full densification and microhardness of 22.9 GPa. A novel process for ceramic coatings on the metallic substrates has been developed successfully by combining chemical bonding and CSG technologies. Non-permeable, crack-free, thick ceramic coatings (2--600 mum) on the substrates were fabricated by spraying and dipping, followed by low temperature (500--600°C) sintering. The correlations between the processing methods, microstructure, and mechanical properties of CSG coatings were investigated by varying the preparation methods, studying morphology, and measuring mechanical properties of the ceramics. The chemically bonded CSG coatings have the best performance. The bonding strength between the substrates and coatings is about 42 MPa, and the surface microhardness of the coatings is about 6.5 GPa.
Functional coatings: the sol-gel approach
Energy Technology Data Exchange (ETDEWEB)
Belleville, Ph. [CEA Centre d' Etudes du Ripault, 37 - Tours (France)
CEA's sol-gel laboratory is specialized in the development of innovative sol-gel optical coatings and has extended its application field to membrane materials and coatings for energy conversion, to electric coatings for microelectronics devices and to thin films for gas sensing. This article describes, by way of examples, the laboratory's research on sol-gel functional coatings, including nano-material synthesis, organic-inorganic hybrid-based solution preparation as well as deposition process development and prototyping. (author)
Sol-gel coatings for electrochromic devices
Macedo, Marcelo A.; Luiz H. Dall'Antonia; Aegerter, Michel A.
Electrochromic devices have potential applications in architectural and automotive fields to regulate the transmission and reflection of the radiant energy. Preliminary characteristics of an all sol-gel window with the configuration glassITOWO3TiO2TiO2-CeO2ITOglass is presented, and compared with another window where WO3 was deposited by evaporation. We also present preliminary data of a sol-gel Nb2O5 electrochromic layer as well as a thorough evaluation of the properties of a sol-gel TiO2-Ce...
Reusable gels for germanium-68 sources
International Nuclear Information System (INIS)
Two water-soluble gels, gelatin and Carbowax, were mixed with radioactive 68Ge solutions and evaluated for their use as long-lived (half-life, 280 days) radioactive sources. These gels melt at 40-50oC and solidify at room temperature. The amount of 68Ge mixed with them can be increased or decreased as needed, eliminating waste of 68Ge. These gel sources also may replace short-lived 68Ga (half-life 68 min) as attenuation correction sources in positron emission tomography (PET) and reduce frequency of source preparation, thus reducing exposure of PET operators to radiation. (author)
Pulsed field gel electrophoresis a practical guide
Birren, Bruce
Pulsed Field Gel Electrophoresis: A Practical Guide is the first laboratory manual to describe the theory and practice of this technique. Based on the authors' experience developing pulsed field gel instruments and teaching procedures, this book provides everything a researcher or student needs to know in order to understand and carry out pulsed field gel experiments. Clear, well-tested protocols assume only that users have a basic familiarity with molecular biology. Thorough coverage of useful data, theory, and applications ensures that this book is also a lasting resource for more adv
Frictional properties of gel engineering materials with laser surface texturing
Yamada, Naoya; Gong, Jin; Kabir, M. Hasnat; Makino, Masato; Maekawa, Keisuke; Wada, Masato; Furukawa, Hidemitsu
Several synthesis methods have been devised to improve the mechanical strength of gels extraordinarily after 2001. It was a trigger to use gels as a new industrial materials, since gels had been considered difficult for industrial materials because of their weakness. In a recent study, we had designed transparency shape memory gels for the first time. Shape memory gels are one of the gels with characteristic networks, and have a shape memory function by copolymerizing an acrylic monomer with a hydrophobic long alkyl side group. It is well known that the mechanical properties such as Young's modulus and friction coefficient of shape memory gels depend on temperature. In this study, we tried to change the frictional properties of shape memory gels by laser surface texturing. Two types of processed surface were prepared. The hexagonal close packed pattern and the square close packed pattern of dimples were formed on the surface of gel sheets with CO2 laser. The intensity of laser was optimized to avoid cutting gels. The friction coefficients of unprocessed gels and two types of processed gels were measured by ball-on-disk method. Measurement partner material was sodalime glass ball. The measurement results of processed gels showed clear differences from unprocessed gels. The friction coefficients of processed gels were larger than unprocessed gels. However, these results specifically showed the velocity dependence. It indicates that surface texturing enable to control the friction coefficient of polymer gels by surface pattern and velocity.
Oxygen-17 relaxation in aqueous agarose gels
International Nuclear Information System (INIS)
Nuclear magnetic relaxation of oxygen-17 in H2 17O enriched agarose gels shows that existing explanations of water behaviour are oversimplified. Satisfactory models must include at least three proton phases, two of which involve water molecules. (Auth.)
International Nuclear Information System (INIS)
A key part of the proposed waste treatment for K Basin sludge is the elimination of reactive uranium metal by dissolution in nitric acid (Fkirnent, 1998). It has been found (Delegard, 1998a) that upon nitric acid dissolution of the sludge, a gel sometimes forms. Gels are known to sometimes impair solid/liquid separation and/or material transfer. The purpose of the work reported here is to determine the cause(s) of the gel formation and to determine operating parameters for the sludge dissolution that avoid formation of gel. This work and related work were planned in (Fkunent, 1998), (Jewett, 1998) and (Beck, 1998a). This report describes the results of the tests in (Beck, 1998a) with non-radioactive surrogates
Radiation protection on polysaccharide solutions and gels
Energy Technology Data Exchange (ETDEWEB)
Bazafkan, Sedighealsharieh
The effects of ionizing radiation on solutions of (1) sodium alginate, (2) alginate gels (wet and dry), (3) xanthan glum, (4), locust bean gum (LBG) and (5) carboxymethyl cellulose (CMC), have been investigated. Problems arise in the radiation sterilization of these gums (either as a solution or gel) due to reduction in their viscosity and the gel strength, caused by the high doses (25kGy) commonly used for the purpose of sterilization. The alginates used here were manugel DMB, manugel DPB and manucol DMF. The irradiations were carried out using {sup 60}Co-{gamma}-source and the gels and solutions were analysed by measurement of their apparent viscosities using a Brookfield viscometer L.V.T. (author).
Sol-gel antireflective coating on plastics
Ashley, Carol S. (Albuquerque, NM); Reed, Scott T. (Albuquerque, NM)
An antireflection film made from a reliquified sol-gel hydrolyzation, condensation polymeric reaction product of a silicon, alkoxides and/or metal alkoxides, or mixtures thereof. The film is particularly useful for coating plastics.
Procedure to prepare transparent silica gels
Barber, Patrick G. (inventor); Simpson, Norman R. (inventor)
This invention relates to the production of silica gels and in particular to a process for the preparation of silica gels which can be used as a crystal growth medium that simulates the convectionless environment of space to produce structurally perfect crystals. Modern utilizations of substances in electronics, such as radio transmitters and high frequency microphones, often require single crystals with controlled purity and structural perfection. The near convectionless environment of silica gel suppresses nucleation, thereby reducing the competitive nature of crystal growth. This competition limits the size and perfection of the crystal; and it is obviously desirable to suppress nucleation until, ideally, only one crystal grows in a predetermined location. A silica gel is not a completely convectionless environment like outer space, but is the closest known environment to that of outer space that can be created on Earth.
Essential characteristics of polymer gel dosimeters
International Nuclear Information System (INIS)
For a physical measurement instrument different requirements have to be fulfilled such as its insensitivity to uncontrollable environmental parameters and its stability. On the other hand, in order to meet an assigned accuracy, all measurement instruments should be operated in an approved manner. Polymer gel dosimeters are unique in their kind as they are able to integrate the dose in three dimensions and can be shaped in a humanoid form. In this paper, we focus on different characteristics that determine the accuracy of polymer gel dosimeters from the point-of-view of their use as 3D dosimeters in radiotherapy. It is shown that the accuracy is highly dependent on the composition of polymer gel. The comparison of the radiological characteristics may help in understanding the underlying mechanisms of the polymer gel dosimeters and in optimizing the chemical composition in terms of both dose and spatial accuracy
Functional gels based on chemically modified graphenes.
Li, Chun; Shi, Gaoquan
Chemically modified graphene (CMG) materials have been extensively studied because of their unique structures, excellent properties, and potential applications in energy storage and conversion, catalysis, and environment remediation. However, the unique two-dimensional structure and amphiphilicity make CMG sheets easily restack into irregular aggregates, which greatly reduces their accessible surface area, and thereby deteriorates their performance in practical applications. To exploit their inherent properties fully, CMGs usually have to be fabricated or assembled into functional gels with desired three-dimensional (3D) interconnected porous microstructures. In this review, we summarize the recent achievements in the synthesis of CMG-based functional gels, including hydrogels, organogels, aerogels, and their composites. The mechanisms of gel formation and the applications of these functional gels will also be discussed. PMID:24659376
Sol-gel deposited electrochromic coatings
Energy Technology Data Exchange (ETDEWEB)
Ozer, N.; Lampert, C.M.
Electrochromic devices have increasing application in display devices, switchable mirrors and smart windows. A variety of vacuum deposition technologies have been used to make electrochromic devices. The sol- gel process offers an alternative approach to the synthesis of optical quality and low cost electrochromic device layers. This study summarizes the developments in sol-gel deposited electrochromic films. The sol-gel process involves the formation of oxide networks upon hydrolysis-condensation of alkoxide precursors. In this study we cover the sol-gel deposited oxides of WO[sub 3], V[sub 2]O[sub 5], TiO[sub 2], Nb[sub 2]O[sub 5], and NiO[sub x].
Maize Arabinoxylan Gels as Protein Delivery Matrices
Directory of Open Access Journals (Sweden)
Ana Luisa Martínez-López
Full Text Available The laccase induced gelation of maize bran arabinoxylans at 2.5% (w/v in the presence of insulin or ?-lactoglobulin at 0.1% (w/v was investigated. Insulin and ?-lacto-globulin did not modify either the gel elasticity (9 Pa or the cross-links content (0.03 and 0.015 mg di- and triferulic acids/mg arabinoxylan, respectively. The protein release capability of the gel was also investigated. The rate of protein release from gels was dependent on the protein molecular weight. The apparent diffusion coefficient was 0.99 × 10-7 and 0.79 × 10-7 cm2/s for insulin (5 kDa and ?-lactoglobulin (18 kDa, respectively. The results suggest that maize bran arabinoxylan gels can be potential candidates for the controlled release of proteins.
Connectivity in sol-gel silica glasses
Vasconcelos Wander L.
In this work it is carried out a review on structural parameters related to the evaluation of pore connectivity of nanostructures. The work describes parameters and methods of evaluation of geometric parameters. The concepts of connectivity are applied to silica gels and glasses obtained from sol-gel process. The study of pores connectivity was carried out using a combination of geometric modeling and experimental evaluation of specific surface area and pore volume. The permeability of the po...
Brillouin scattering from cross-linked gels
Mallamace, Francesco; Micali, Norberto; Vasi, Cirino; Bansil, Rama; Pajevic, Sinisa; Sciortino, Francesco
In this letter we report Brillouin scattering measurements on methyl-methacrylate (MMA) gels crosslinked with varying amounts of ethylene-dimethacrylate (EDMA). We find that the k dependence of the phase velocity changes on increasing the cross-link content. For higher concentrations of crosslink we observe maxima and minima in the k dependence of the phase velocity. We associate these minima and maxima with spatial inhomogeneities in the gel, with the formation of regions of low and high cro...
Dr. Shashikant D. Barhate
High molecular weight water soluble homopolymer of carbapol 934P resins are reported to possess very high viscosity in low concentration, transparency and film forming properties useful for gels. The meloxicam sodium gels were prepared by varying the concentration of penetration enhancer's ethanol, PEG 400, menthol and azone. Selection of optimized batch was done on the basis of results of rheological studies and in-vitro drug permeation. Formulation F19 with highest amount of menthol shows...
The yielding dynamics of a colloidal gel
Gibaud, Thomas; Frelat, Damien; Manneville, Se?bastien
Attractive colloidal gels display a solid-to-fluid transition as shear stresses above the yield stress are applied. This shear-induced transition is involved in virtually any application of colloidal gels. It is also crucial for controlling material properties. Still, in spite of its ubiquity, the yielding transition is far from understood, mainly because rheological measurements are spatially averaged over the whole sample. Here, the instrumentation of creep and oscillatory...
Drying and Rehydration of Calcium Alginate Gels:
Vreeker, R.; Li, L.; Fang, Y.; Appelqvist, I.; Mendes, E.
In this paper, we study the rehydration properties of air-dried calcium alginate gel beads. Rehydration is shown to depend on alginate source (i.e. mannuronic to guluronic acid ratio) and the salt concentration in the rehydration medium. Rehydration curves are described adequately by the empirical Weibull equation. Wide-angle X-ray diffraction measurements are performed to obtain information on the microstructure of dried alginate gels. The X-ray diffraction patterns provide evidence for form...
Conducting Polymer Electrodes for Gel Electrophoresis
Bengtsson, Katarina; Nilsson, Sara; Robinson, Nathaniel D.
In nearly all cases, electrophoresis in gels is driven via the electrolysis of water at the electrodes, where the process consumes water and produces electrochemical by-products. We have previously demonstrated that p-conjugated polymers such as poly(3,4-ethylenedioxythiophene) (PEDOT) can be placed between traditional metal electrodes and an electrolyte to mitigate electrolysis in liquid (capillary electroosmosis/electrophoresis) systems. In this report, we extend our previous result to gel ...
Brownian Dynamics simulations of aging colloidal gels
D Arjuzon, Rodolphe J. M.; Frith, William; Melrose, John R.
Colloidal gel aging is investigated using very long runs of brownian dynamics simulations. The Asakura Oosawa description of the depletion interaction is used to model a simple colloid polymer mixture. Several regimes are identified during gel formation. The Intermediate scattering function displays a double decay characteristic of systems where some kinetic processes are frozen. The $\\beta$ relaxation at short times is explained in terms of the Krall-Weitz model for the dec...
Particle size analysis of PAGAT gel dosimetry
Samuel, E. J. J.; Sathiyaraj, P.; Titus, D.; Kumar, D. S.
This work represents the response of PAGAT gel dosimeter using UV-Visible Spectrophotometry. The particle size and optimal wavelength of the gel sample were analyzed from the obtained spectrum. In addition, the compressibility was estimated using Ultrasonic Interferometer. The results showed that the particle size of the PAGAT varied appreciably with respect to the dose applied but did not vary significantly with the post irradiation time.
Prevalence of Gumboro disease in vaccinated and non-vaccinated village chickens in Egypt
International Nuclear Information System (INIS)
In order to investigate the incidence of Gumboro disease virus (IBDV) in village poultry in Egypt, 3000 one-day-old Balady chicks were distributed to 60 householders keeping free- ranging chicken (traditional) with an average of 50 chicks/ household. These were put under observed from one-day-old until seventy days of age and visited once a week. On 30 of these household farms the one-day-old chicken were vaccinated before delivery with an intermediate IBDV strain while the chicken on the other 30 farms were not vaccinated. Fifteen of each vaccinated and unvaccinated householder farms had other avian species while the other fifteen of each vaccinated and unvaccinated householders had not. The clinical symptoms, post-mortem and serological results using the Agar Gel Immuno-diffusion test (AGID) revealed that Gumboro disease is one of the most important diseases in rural chicken. Mortality rates were very high (5-32%) and decreasing body weights due to IBDV infection were significant, especially in chicken reared with other avian species. Results from the survey showed the significant efficacy of IBDV classical vaccine in one day old chicken. It showed a decrease in mortality and an increase in body weight gain on vaccinated farms independent whether they were kept with other avian species. Vaccination programs to control Gumboro disease would be an advantage in traditional poultry farms. (author)
Optimized MR imaging for polyacrylamide gel dosimetry
International Nuclear Information System (INIS)
Polyacrylamide gels are a powerful tool to measure radiation dose by quantifying the NMR T2 relaxation times of the irradiated gel. The exploitation of these radiation sensitive gels in clinical radiotherapy requires accurate mapping of T2 values. This paper describes the optimization strategy used to identify accurate and practical methods of measuring the range of T2 values typical of gel dosimeters (140-700 ms). The MR imaging techniques used to measure T2 values and the choice of image acquisition parameters are described. Four sequences are compared and the results are analysed in terms of accuracy, signal-to-noise ratio and acquisition time. A multiple spin echo sequence was found to yield the most accurate results (98.9%). Single spin echo sequences, such as Hahn spin echo and EPI spin echo, were found to measure gel T2 values with an accuracy of 90.1%. This paper reports the importance of careful selection and optimization of the MR imaging sequences for accurate and reliable polyacrylamide gel dosimetry. (author)
Treatment of osteochondral injuries with platelet gel
Scientific Electronic Library Online (English)
Marcus Vinicius, Danieli; Hamilton da Rosa, Pereira; Carlos Augusto de Sá, Carneiro; Sérgio Luiz, Felisbino; Elenice, Deffune.
Full Text Available OBJECTIVES: Treatments for injured articular cartilage have not advanced to the point that efficient regeneration is possible. However, there has been an increase in the use of platelet-rich plasma for the treatment of several orthopedic disorders, including chondral injuries. Our hypothesis is tha [...] t the treatment of chondral injuries with platelet gel results in higher-quality repair tissue after 180 days compared with chondral injuries not treated with gel. METHODS: A controlled experimental laboratory study was performed on 30 male rabbits to evaluate osteochondral injury repair after treatment with or without platelet gel. Osteochondral injuries were surgically induced in both knees of each rabbit at the medial femoral condyle. The left knee injury was filled with the platelet gel, and the right knee was not treated. Microscopic analysis of both knee samples was performed after 180 days using a histological grading scale. RESULTS: The only histological evaluation criterion that was not significantly different between treatments was metachromasia. The group that was treated with platelet gel exhibited superior results in all other criteria (cell morphology, surface regularity, chondral thickness and repair tissue integration) and in the total score. CONCLUSION: The repair tissue was histologically superior after 180 days in the study group treated with platelet gel compared with the group of untreated injuries.
Fricke xylenol gel energy dependence
International Nuclear Information System (INIS)
The advancement of technology has increasingly use the of ionizing radiation mainly in the areas of medicine, industry and research. The development of instruments and methods for an effective performance for detection and measurement of each radiation area was crucial. The literature have demonstrated the effectiveness of the Fricke Xylenol Gel (FXG) as an adequate chemical sensor to be used for dosimetry, once its effective atomic number and density are near to those of the soft tissue. The use of photon beams for therapeutic purpose requires knowledge of their characteristics that can vary for each equipment. Therefore, is important to know all parameters involved for the patient irradiation as the total geometry involved, type of radiation, target material composition and beam energy, that have to be taken into account in the beam dosimetry for the treatment success being the energy parameter is one of the most important. This work was developed to study the energetic dependence of the FXG dosimeter. This chemical solution is made with gelatine 300 Bloom, ferrous ammonium sulfate, xylenol orange, sulfuric acid and Milli-Q water and is based on the Fe+2 oxidation to Fe+3, due to the ionizing radiation leading to the xylenol orange - ferric complex formation, that is linear depend on the absorbed dose. The FXG samples were irradiated with photons of different energies and the absorbance measurements were done with the spectrophotometric technique at the 585 nm, FXG highest absorption peak. The energetic dependence results presented a stronger dependence for low energies and almost independence for high energies, as expected by the interaction of radiation with matter. (author)
Uncertainty in 3D gel dosimetry
De Deene, Yves; Jirasek, Andrew
Three-dimensional (3D) gel dosimetry has a unique role to play in safeguarding conformal radiotherapy treatments as the technique can cover the full treatment chain and provides the radiation oncologist with the integrated dose distribution in 3D. It can also be applied to benchmark new treatment strategies such as image guided and tracking radiotherapy techniques. A major obstacle that has hindered the wider dissemination of gel dosimetry in radiotherapy centres is a lack of confidence in the reliability of the measured dose distribution. Uncertainties in 3D dosimeters are attributed to both dosimeter properties and scanning performance. In polymer gel dosimetry with MRI readout, discrepancies in dose response of large polymer gel dosimeters versus small calibration phantoms have been reported which can lead to significant inaccuracies in the dose maps. The sources of error in polymer gel dosimetry with MRI readout are well understood and it has been demonstrated that with a carefully designed scanning protocol, the overall uncertainty in absolute dose that can currently be obtained falls within 5% on an individual voxel basis, for a minimum voxel size of 5 mm3. However, several research groups have chosen to use polymer gel dosimetry in a relative manner by normalizing the dose distribution towards an internal reference dose within the gel dosimeter phantom. 3D dosimetry with optical scanning has also been mostly applied in a relative way, although in principle absolute calibration is possible. As the optical absorption in 3D dosimeters is less dependent on temperature it can be expected that the achievable accuracy is higher with optical CT. The precision in optical scanning of 3D dosimeters depends to a large extend on the performance of the detector. 3D dosimetry with X-ray CT readout is a low contrast imaging modality for polymer gel dosimetry. Sources of error in x-ray CT polymer gel dosimetry (XCT) are currently under investigation and include inherent limitations in dosimeter homogeneity, imaging performance, and errors induced through post-acquisition processing. This overview highlights a number of aspects relating to uncertainties in polymer gel dosimetry.
Characterization of schistosome antigens by SDS-polyacrylamide gel electrophoresis
International Nuclear Information System (INIS)
Separation of polypeptides by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) is based upon the relationship between the electrophoretic mobility of SDS-protein complexes and their molecular weights. Tegumental proteins extracted from Schistosoma mansoni have been analyzed by SDS-PAGE using slab gels by a number of investigators. Valuable information has also been obtained using tube gels to analyze radiolabeled proteins. The procedures for electrophoresis using tube gels and electrophoresis using gradient slab gels are described
Evolution of gel structure during thermal processing of Na-geopolymer gels.
Duxson, Peter; Lukey, Grant C; van Deventer, Jannie S J
The present work examines how the gel structure and phase composition of Na-geopolymers derived from metakaolin with varied Si/Al ratio evolve with exposure to temperatures up to 1000 degrees C. Gels were thermally treated and characterized using quantitative XRD, DTA, and FTIR to elucidate the changes in gel structure, phase composition, and porosity at each stage of heating. It is found that the phase stability, defined by the amount and onset temperature of crystallization, is improved at higher Si/Al ratios. Two different mechanisms of densification have been isolated by FTIR, related to viscous flow and collapse of the highly distributed pore network in the gel. Gels with low Si/Al ratio only experience viscous flow that correlates with low thermal shrinkage. Gels at a higher Si/Al ratio, which have a homogeneous microstructure composed of a highly distributed porosity, undergo both densification processes corresponding to a large extent of thermal shrinkage during densification. This work elucidates the intimate relationship between gel microstructure, chemistry, and thermal evolution of Na-geopolymer gels. PMID:17014113
Mucosal effects of tenofovir 1% gel.
Hladik, Florian; Burgener, Adam; Ballweber, Lamar; Gottardo, Raphael; Vojtech, Lucia; Fourati, Slim; Dai, James Y; Cameron, Mark J; Strobl, Johanna; Hughes, Sean M; Hoesley, Craig; Andrew, Philip; Johnson, Sherri; Piper, Jeanna; Friend, David R; Ball, T Blake; Cranston, Ross D; Mayer, Kenneth H; McElrath, M Juliana; McGowan, Ian
Tenofovir gel is being evaluated for vaginal and rectal pre-exposure prophylaxis against HIV transmission. Because this is a new prevention strategy, we broadly assessed its effects on the mucosa. In MTN-007, a phase-1, randomized, double-blinded rectal microbicide trial, we used systems genomics/proteomics to determine the effect of tenofovir 1% gel, nonoxynol-9 2% gel, placebo gel or no treatment on rectal biopsies (15 subjects/arm). We also treated primary vaginal epithelial cells from four healthy women with tenofovir in vitro. After seven days of administration, tenofovir 1% gel had broad-ranging effects on the rectal mucosa, which were more pronounced than, but different from, those of the detergent nonoxynol-9. Tenofovir suppressed anti-inflammatory mediators, increased T cell densities, caused mitochondrial dysfunction, altered regulatory pathways of cell differentiation and survival, and stimulated epithelial cell proliferation. The breadth of mucosal changes induced by tenofovir indicates that its safety over longer-term topical use should be carefully monitored. PMID:25647729
Energy Technology Data Exchange (ETDEWEB)
Physical and chemical agents in the environment, those used in clinical applications, or encountered during recreational exposures to sunlight, induce damages in DNA. Understanding the biological impact of these agents requires quantitation of the levels of such damages in laboratory test systems as well as in field or clinical samples. Alkaline gel electrophoresis provides a sensitive (down to {approx} a few lesions/5Mb), rapid method of direct quantitation of a wide variety of DNA damages in nanogram quantities of non-radioactive DNAs from laboratory, field, or clinical specimens, including higher plants and animals. This method stems from velocity sedimentation studies of DNA populations, and from the simple methods of agarose gel electrophoresis. Our laboratories have developed quantitative agarose gel methods, analytical descriptions of DNA migration during electrophoresis on agarose gels (1-6), and electronic imaging for accurate determinations of DNA mass (7-9). Although all these components improve sensitivity and throughput of large numbers of samples (7,8,10), a simple version using only standard molecular biology equipment allows routine analysis of DNA damages at moderate frequencies. We present here a description of the methods, as well as a brief description of the underlying principles, required for a simplified approach to quantitation of DNA damages by alkaline gel electrophoresis.
Directory of Open Access Journals (Sweden)
Sunil Kumar
Full Text Available The purpose of this research is to design proniosomal gel drug delivery system of flurbiprofen in a trial to overcome the adverse effects associated with oral administration of the drug. This can be overcome by the use of vesicular drug delivery system. Encapsulation of a drug in vesicular structure can be predicted to prolong the existence of the drug in the systemic circulation and thus enhance penetration into target tissue and reduce toxicity. Proniosomal gels are generally present in transparent, translucent or white semisolid gel texture. Due to the limited solvent system present, the proniosomes formed were the mixture of many phases of liquid crystal, viz. lamellar, hexagonal and cubic phase liquid crystals. The potential of proniosomes as a transdermal drug delivery system for flurbiprofen was investigated by encapsulating the drug in various formulations of proniosomal gel composed of various ratios of sorbitan fatty acid esters, cholesterol, prepared by coacervation-phase separation method. The formulated systems were characterized in vitro for size, vesicle count, drug entrapment, drug release profiles and vesicular stability at different storage conditions. Stability studies for proniosomal gel were carried out for 4 weeks. The method of proniosome loading resulted in an encapsulation yield of 30.6 – 75.4%. Proniosomes were characterised by transmission electron microscopy. In vitro studies showed prolonged release of entrapped flurbiprofen. At refrigerated conditions, higher drug retention was observed. It is evident from this study that proniosomes are a promising prolonged delivery system for captopril and have reasonably good stability characteristics.
Carbon gels derived from natural resources
Directory of Open Access Journals (Sweden)
A. Celzard
Full Text Available Most carbon gels investigated so far and reportedin the literature were prepared from resorcinolcrosslinked with formaldehyde in water, and weregenerally dried with supercritical CO2 before beingpyrolysed. In the present paper, through someselected examples, we show how valuable carbongels can be derived from other phenolic resourceshaving a natural origin. Special emphasis is givento tannin and lignin, both derived from wood, aspotential precursors of carbon aero- and cryogels.However, natural compounds not obeying the usualconcepts of sol-gel chemistry may also be used forpreparing carbon gels, such as cellulose, and evenglucose. In the latter case, hydrothermal treatmentforces the phase separation to occur, and leads tomonoliths which can be advantageously convertedinto carbon aerogels by supercritical drying andsubsequent pyrolysis.
Sol-gel synthesis of hydroxyapatite
International Nuclear Information System (INIS)
Hydroxyapatite (HAp) has been established as the calcium phosphate based compound with most applications in the biological field. Among the numerous techniques for synthesis of HAp, the sol-gel processing route affords great control over purity and formed phases using low processing temperatures. In addition, the sol-gel approach offers an option for homogeneous HAp coating on metal substrates, as well as the ability to generate nanocrystalline powders. In this work, the sol-gel synthesis of HAp was investigated employing triethyl phosphate and calcium nitrate tetrahydrate as phosphorous and calcium precursors, respectively. The aging effect on phase composition and powder morphology of the final product was studied in terms of temperature and aging time. The powders were studied by using X-ray diffraction, Fourier transform infrared spectroscopy, particle size distribution by laser diffraction and scanning electron microscopy. (author)
Superconductive ceramics obtained with sol gel method
International Nuclear Information System (INIS)
Several sol gel routes have been considered, studied and developed to produce large quantities of granulates which can be processed to obtain ceramics having good superconducting characteristics. In the considered process a mixture of commercial nitrates is atomized, at room temperature, in a solution 1:1 of Primene JMT and Benzene and a pale blue gel of the starting elements is suddently formed. The granulates obtained are free flowing, very reactive and well suited for pressing. For their intrinsic characteristics they could be very good precursors for the production of large quantities of superconductive ceramics in different forms. The precipitated gel is dried, calcinated, pressed in the form of cylindrical pellets which are sintered up to 960 degrees C. No griding or different thermal treatments are needed. The sintered material has low electric resistence, shows a clear Meissner effect and has a transition temperature of between 91 and 95 K
Multiple-phase behavior and memory effect of polymer gel
International Nuclear Information System (INIS)
A poly(4-acrylamidosalicylic acid) gel (PASA gel) exhibits multiple phases as characterized by distinct degrees of swelling; the gel can take one of four different swelling values, but none of the intermediate values. The gel has remarkable memory: the phase behavior of the gel depends on whether the gel has experienced the most swollen phase or the most collapsed phase in the immediate past. The information is stored and reversibly erased in the form of a macroscopic phase transition behavior. The structure factors corresponding to these four phases were obtained by SANS, which indicated the presence of characteristic structures depending on pH and temperature, particularly in the shrunken state. (orig.)
Iron(II)- or vanadium(IV)-containing siliceous gels
Hutter, Frank; Schmidt, Helmut K.; Scholze, Horst
Iron(II)-containing SiO2 gels can be prepared by the hydrolysis and condensation of tetramethoxysilane in methanolic solutions of iron(II) chloride. These gels show an absorption at 1000 nm indicating the presence of iron(II). In opposition to that, iron(II) cannot be introduced into organically modified gels of the 3-glycidyloxypropyltrimethoxysilane type. Vanadium(IV) can be incorporated into both gels. Unlike the SiO2 gels, the organically modified gels are compact and elastic. The spectra...
Multiple-phase behavior and memory effect of polymer gel
Annaka, M; Nakahira, T; Sugiyama, M; Hara, K; Matsuura, T
A poly(4-acrylamidosalicylic acid) gel (PASA gel) exhibits multiple phases as characterized by distinct degrees of swelling; the gel can take one of four different swelling values, but none of the intermediate values. The gel has remarkable memory: the phase behavior of the gel depends on whether the gel has experienced the most swollen phase or the most collapsed phase in the immediate past. The information is stored and reversibly erased in the form of a macroscopic phase transition behavior. The structure factors corresponding to these four phases were obtained by SANS, which indicated the presence of characteristic structures depending on pH and temperature, particularly in the shrunken state. (orig.)
The mechanism and properties of acid-coagulated milk gels
Directory of Open Access Journals (Sweden)
Chanokphat Phadungath
Full Text Available Acid-coagulated milk products such as fresh acid-coagulated cheese varieties and yogurt areimportant dairy food products. However, little is known regarding the mechanisms involved in gel formation, physical properties of acid gels, and the effects of processing variables such as heat treatment and gelation temperature on the important physical properties of acid milk gels. This paper reviews the modern concepts of possible mechanisms involved in the formation of particle milk gel aggregation, along with recent developments including the use of techniques such as dynamic low amplitude oscillatory rheology to observe the gel formation process, and confocal laser scanning microscopy to monitor gel microstructure.
Neutron detector using sol-gel absorber
Hiller, John M. (Oak Ridge, TN); Wallace, Steven A. (Oak Ridge, TN); Dai, Sheng (Knoxville, TN)
An neutron detector composed of fissionable material having ions of lithium, uranium, thorium, plutonium, or neptunium, contained within a glass film fabricated using a sol-gel method combined with a particle detector is disclosed. When the glass film is bombarded with neutrons, the fissionable material emits fission particles and electrons. Prompt emitting activated elements yielding a high energy electron contained within a sol-gel glass film in combination with a particle detector is also disclosed. The emissions resulting from neutron bombardment can then be detected using standard UV and particle detection methods well known in the art, such as microchannel plates, channeltrons, and silicon avalanche photodiodes.
Hybrid sol-gel optical materials
Zeigler, John M. (Albuquerque, NM)
Hybrid sol-gel materials comprise silicate sols cross-linked with linear polysilane, polygermane, or poly(silane-germane). The sol-gel materials are useful as optical identifiers in tagging and verification applications and, in a different aspect, as stable, visible light transparent non-linear optical materials. Methyl or phenyl silicones, polyaryl sulfides, polyaryl ethers, and rubbery polysilanes may be used in addition to the linear polysilane. The linear polymers cross-link with the sol to form a matrix having high optical transparency, resistance to thermooxidative aging, adherence to a variety of substrates, brittleness, and a resistance to cracking during thermal cycling.
Alignment and nonlinear elasticity in biopolymer gels
Feng, Jingchen; Levine, Herbert; Mao, Xiaoming; Sander, Leonard M.
We present a Landau-type theory for the nonlinear elasticity of biopolymer gels with a part of the order parameter describing induced nematic order of fibers in the gel. We attribute the nonlinear elastic behavior of these materials to fiber alignment induced by strain. We suggest an application to contact guidance of cell motility in tissue. We compare our theory to simulation of a disordered lattice model for biopolymers. We treat homogeneous deformations such as simple shear, hydrostatic expansion, and simple extension, and obtain good agreement between theory and simulation. We also consider a localized perturbation which is a simple model for a contracting cell in a medium.
Development of Stable Restructured Mango Gel
Das Gupta, D. K.; Roopa, N.; Leela, R. K.
Restructured mango gel was prepared by alginate texturization of mango pulp using sodium alginate, glucono-?-lactone and calcium hydrogen orthophosphate. The requisite quantities of the chemical additives were mixed, added together to the neutralized mango pulp in a mixer and allowed to set at 4°C for 16 h. The mango gel was cut into 1.5 cm cubes and stabilized by Hurdle Technology (HT) through adjustment of water activity to 0.89, pH 4.4 and pasteurization in polypropylene pouches. Storage...
Electroactive polymer gels based on epoxy resin
Samui, A. B.; Jayakumar, S.; Jayalakshmi, C. G.; Pandey, K.; Sivaraman, P.
Five types of epoxy gels have been synthesized from common epoxy resins and hardeners. Fumed silica and nanoclay, respectively, were used as fillers and butyl methacrylate/acrylamide were used as monomer(s) for making interpenetrating polymer networks (IPNs) in three compositions. Swelling study, tensile property evaluation, dynamic mechanical thermal analysis, thermo-gravimetric analysis, scanning electron microscopy and electroactive property evaluation were done. The gels have sufficient mechanical strength and the time taken for bending to 20° was found to be 22 min for forward bias whereas it was just 12 min for reverse bias.
Aggregation-structure-elasticity relationship of gels
Ma, Hang-Shing
Aerogel is a mesoporous, low-density material which is desirable for applications like thermal insulation and low-k interlayer dielectric. However, its lack of mechanical integrity hinders its development. Experiments have shown that aerogels exhibit a scaling relationship E ? rho m between modulus E and density rho, with the exponent m usually between 3 and 4. The objective of the dissertation is to use computer modeling to understand how the random aggregation process accounts for the fractal structure and the compliant nature of aerogels. Model gels were created by the diffusion-limited cluster-cluster aggregation (DLCA), which simulates random aggregation leading to the sol-gel transition. Then each resulting structure was modeled as an elastic beam network and numerically compressed using the finite element method (FEM). Analyses showed that the DLCA gels reproduced the scaling relationship after trimming the non-contributive dangling branches from the mechanically efficient looped networks. The dangling bond deflection (DEF) model was therefore developed to model the random rotational movement of the dangling branches and the subsequent loop structure formation. Model gels with extensive loops and negligible dangling branches were simulated by combining the DLCA and DEF models. Representation of the aerogel networks by the DLCADEF models was validated for the resemblance of the fractal geometry and elastic behavior. The lack of mechanical integrity in aerogels is a natural consequence of the random aggregation and the resulting fractal structure. Fractal clusters are created in the early stage of aggregation, each of which is characterized by a dense core and sparse perimeter. These clusters grow in size until they percolate at the gel point by knitting together at the perimeters. The gel structure possesses a "blob-and-link" architecture, with the blobs representing the rigid cores of the fractal clusters, and the links corresponding to the tenuous chains formed between the clusters at percolation. Finite element analysis illustrates that the strain energy always localizes at the links in the DLCADEF gels. Therefore the stiffness of an aerogel is reduced by the presence of these compliant links. The key to synthesizing stiffer gels is to homogenize the distribution and cross-linking of mass during the formation of the network.
Predictive value of serologic tests in the diagnosis and follow-up of patients with paracoccidioidomycosis / Valor predictivo de las pruebas serologicas para el diagnostico y seguimiento de la paracoccidoidomycosis
Scientific Electronic Library Online (English)
Luz Elena, Cano; Angela, Restrepo.
Full Text Available Con el objeto de determinar el valor predictivo de las pruebas serológicas (Fˇjación de Complemento, FC, e Inmunodifusión en Gel de Agar, IDGA), utilizadas regularmente en nuestro laboratorio para el diagnóstico y el seguimiento de la paracoccidioidomicosis, se analizaron los datos provenientes de 4 [...] 3 pacientes con la enfermedad. Tales pacientes fueron tratados en forma identica (Ketoconazol, 200 mg/dia por 6 meses); además ambas pruebas serológicas utilizaron un mismo lote de antigeno, eliminando asi posibles variables. Fuera de los sueros provenientes de los 43 pacientes con paracoccidioidomicosis (A), se estudiaron 50 sueros de pacientes con otras micosis profundas (B) y 92 sueros de personas sanas (C). Empleamos las fórmulas dadas por GALEN y GAMBINO6 y hallamos que la sensibilidad de ambas pruebas serológicas era comparable, sin diferencia estadísticamente significativa entre ellas (FC = 93%, IDGA - 88.4%). Dicha sesibilidad tendia a disminuir con el tratamiento, siendo más marcada su baja durante las observaciones post-terapia. Al analizar la especificidad se encontró que la IDGA era totalmente específica, no encontrandose falsos positivos en las poblaciones controles estudiadâs (B y C). La FC mostró un 96.7% de especificidad frente a la población C y un 82% frente a la B, siendo estadistisarnente significativa la diferencia entre ambas. Basados en los datos ariteriores, se buscó et valor predictivo, hallaridose que la IDGA da seguridad completa para el diagnóstiso en cualquiera de los períodos evaluados no asi la FC, la que mostró disminución de tales valores durante la terapia y la post-terapia. La curva respectiva mostró como a medida que pasaba el tiempo, disminuía la posibiildad de diferenciar la paracoccidioidomicosis (A) de otras micosis (B), manteniendose, sinembargo, la diferencia con los controles normales (C). Abstract in english A serologic study was undertaken in a group of 43 patients with active paracoccidioidomycosis who were treated in the same form (ketoconazole), for identical periods of time (6 months), and folio wed-up for various periods posttherapy. The tests employed were agar gel immunodiffusion (AGID) and comp [...] lement fixation (FC). Also studied were 50 sera from patients with proven histoplasmosis and pulmonary aspergilloma, 30 patients with culturaly proven tuberculosis as well as 92 specimens from healthy individuals, residents in the endemic area for paracoccidioidomycosis. A single lot of yeast filtrate antigen was used throughout the study. The value of each test was measured according to GALEN and GAMBINO6. Both tests were highly sensitive, 89 and 93% respectively. Regarding their specificity, the AGID was totally specific while the CF exhibited 96.6% and 97% specificity in front of tuberculosis patients and healthy individuals respectively and 82% in comparison with patients with other mycoses. The concept of predictive value, that is, the certainty one has in accepting a positive test as diagnostic of paracoccidioidomycosis, favored the AGID procedure (100%) over the CF test. The latter could sort out with 93% certainty a patient with paracoccidioidomycosis among a group of healthy individuals and with 97.5% in the case of TB patients; when the group in question was composed by individuals with other deep mycoses, such certainty was lower (81%). The above results indicate that both the AGID and the CF tests furnish results of high confidence; one should not relay, however, in the CF alone as a means to establish the specific diagnosis of paracoccidioidomycosis.
Lentivírus em caprinos leiteiros do semiárido paraibano: prevalęncia de anticorpos, fatores de risco e detecçăo molecular / Lentivirus in dairy goats from the semiarid region of Paraiba state: seroprevalence, risk factors and molecular detection
Scientific Electronic Library Online (English)
Maria L.C.R., Silva; Roberto S., Castro; Rita C., Maia; Sergio A., Nascimento; Ana Lisa V., Gomes; Sérgio S., Azevedo.
Full Text Available Os objetivos do presente trabalho foram determinar a prevalęncia de caprinos leiteiros soropositivos para a infecçăo por Lentivirus de pequenos ruminantes no semiárido do Estado da Paraíba, Nordeste do Brasil, identificar fatores de risco associados ŕ prevalęncia de rebanhos positivos, e realizar a [...] detecçăo molecular do agente. Foram utilizadas 1047 cabras leiteiras de 110 propriedades selecionadas aleatoriamente no Município de Monteiro, Estado da Paraíba, no período de março de 2009 a dezembro de 2011. Para o diagnóstico da infecçăo por Lentivirus, foi utilizado o teste de imunodifusăo em gel de ágar (AGID). Um ano após foi realizada nova sorologia, e PCR em tempo real foi aplicada em amostras de sangue e leite de 48 cabras procedentes de quatro propriedades com animais soropositivos. As prevalęncias de propriedades positivas e de animais soropositivos na AGID foram 44,6% (IC 95% = 35,1% - 54,3%) e 8,1% (IC 95% = 5,6% - 16,8%), respectivamente. Realizar corte e desinfecçăo de umbigo (odds ratio = 2,44; p = 0,048) e condiçőes de aglomeraçăo de animais (odds ratio = 3,45; p = 0,048) foram associadas com a prevalęncia de propriedades positivas. Um ano após a realizaçăo do inquérito sorológico, foi verificada a permanęncia de animais infectados, detectados por PCR em tempo real a partir de amostras de sangue e leite. A PCR em tempo real das amostras de leucócitos circulantes apresentou boa performance, com sensibilidade de 100%, especificidade de 92,86%, concordância de 93,75% e indicador Kappa de 0,765. Sugere-se que seja realizado um trabalho de educaçăo sanitária junto aos produtores sobre medidas de prevençăo com o objetivo de reduzir a disseminaçăo da infecçăo nos rebanhos. Abstract in english The aims of this study were to determine the seroprevalence of infection by ruminants Lentivirus in dairy goats in the semiarid of the Paraiba State, Northeastern Brazil, to identify risk factors associated with the herd-level prevalence and to perform molecular detection of the agent. A total of 1, [...] 047 dairy goats from 110 herds were randomly selected from the county of Monteiro, Paraiba State, and serum samples were collected from March 2009 to December 2011. For the diagnosis of Lentivirus infection, the agar gel immunodiffusion test (AGID) was used. One year after that a new serology was performed and the real-time PCR assay was applied in blood and milk samples from 48 goats from four herds with seropositive animals. Prevalence of positive herds and seropositive animals at AGID were 44.6% (95% CI=35.1-54.3%) and 8.1% (95% CI =5.6-16.8%), respectively. Umbilical cord cutting and disinfection (odds ratio = 2.44; p = 0.048) and conditions of animal agglomeration (odds ratio=3.45; p=0.048) were associated with herd-level prevalence. One year after the serological profile, the permanence of infected animals detected by real-time PCR in blood and milk samples was verified. Real-time PCR using white blood cells had a good performance, with sensitivity of 100%, specificity of 92.86%, concordance of 93.75% and Kappa index of 0.765. It was suggested to teach sanitary measures to the herd owners in order to encourage them to adopt prevention measures aiming to reduce the spread of the infection in the herds.
Predictive value of serologic tests in the diagnosis and follow-up of patients with paracoccidioidomycosis Valor predictivo de las pruebas serologicas para el diagnostico y seguimiento de la paracoccidoidomycosis
Directory of Open Access Journals (Sweden)
Luz Elena Cano
Full Text Available A serologic study was undertaken in a group of 43 patients with active paracoccidioidomycosis who were treated in the same form (ketoconazole, for identical periods of time (6 months, and folio wed-up for various periods posttherapy. The tests employed were agar gel immunodiffusion (AGID and complement fixation (FC. Also studied were 50 sera from patients with proven histoplasmosis and pulmonary aspergilloma, 30 patients with culturaly proven tuberculosis as well as 92 specimens from healthy individuals, residents in the endemic area for paracoccidioidomycosis. A single lot of yeast filtrate antigen was used throughout the study. The value of each test was measured according to GALEN and GAMBINO6. Both tests were highly sensitive, 89 and 93% respectively. Regarding their specificity, the AGID was totally specific while the CF exhibited 96.6% and 97% specificity in front of tuberculosis patients and healthy individuals respectively and 82% in comparison with patients with other mycoses. The concept of predictive value, that is, the certainty one has in accepting a positive test as diagnostic of paracoccidioidomycosis, favored the AGID procedure (100% over the CF test. The latter could sort out with 93% certainty a patient with paracoccidioidomycosis among a group of healthy individuals and with 97.5% in the case of TB patients; when the group in question was composed by individuals with other deep mycoses, such certainty was lower (81%. The above results indicate that both the AGID and the CF tests furnish results of high confidence; one should not relay, however, in the CF alone as a means to establish the specific diagnosis of paracoccidioidomycosis.Con el objeto de determinar el valor predictivo de las pruebas serológicas (Fˇjación de Complemento, FC, e Inmunodifusión en Gel de Agar, IDGA, utilizadas regularmente en nuestro laboratorio para el diagnóstico y el seguimiento de la paracoccidioidomicosis, se analizaron los datos provenientes de 43 pacientes con la enfermedad. Tales pacientes fueron tratados en forma identica (Ketoconazol, 200 mg/dia por 6 meses; además ambas pruebas serológicas utilizaron un mismo lote de antigeno, eliminando asi posibles variables. Fuera de los sueros provenientes de los 43 pacientes con paracoccidioidomicosis (A, se estudiaron 50 sueros de pacientes con otras micosis profundas (B y 92 sueros de personas sanas (C. Empleamos las fórmulas dadas por GALEN y GAMBINO6 y hallamos que la sensibilidad de ambas pruebas serológicas era comparable, sin diferencia estadísticamente significativa entre ellas (FC = 93%, IDGA - 88.4%. Dicha sesibilidad tendia a disminuir con el tratamiento, siendo más marcada su baja durante las observaciones post-terapia. Al analizar la especificidad se encontró que la IDGA era totalmente específica, no encontrandose falsos positivos en las poblaciones controles estudiadâs (B y C. La FC mostró un 96.7% de especificidad frente a la población C y un 82% frente a la B, siendo estadistisarnente significativa la diferencia entre ambas. Basados en los datos ariteriores, se buscó et valor predictivo, hallaridose que la IDGA da seguridad completa para el diagnóstiso en cualquiera de los períodos evaluados no asi la FC, la que mostró disminución de tales valores durante la terapia y la post-terapia. La curva respectiva mostró como a medida que pasaba el tiempo, disminuía la posibiildad de diferenciar la paracoccidioidomicosis (A de otras micosis (B, manteniendose, sinembargo, la diferencia con los controles normales (C.
SAXS study of silica sols, gels and glasses obtained by the sol gel process
International Nuclear Information System (INIS)
Systematic SAXS studies have been performed at the LURE Synchrotron, Orsay, using an intense beam of point like cross-section to obtain information about the sol -> humid gel -> dried gel -> silica glass transformation. The intensity curves have been analysed in term of power law in log-log plots, whose exponent is related to mass and surface fractal dimensions of the structure. It was found that almost all phases present fractal structures and for the case of basic gels, is of hierarchical nature. The aerogels are formed by a dense matrix, with a smooth surface and exhibit a very narrow auto-similarity range that gives a mass fractal dimension. (author)
3D gel printing for soft-matter systems innovation
Furukawa, Hidemitsu; Kawakami, Masaru; Gong, Jin; Makino, Masato; Kabir, M. Hasnat; Saito, Azusa
In the past decade, several high-strength gels have been developed, especially from Japan. These gels are expected to use as a kind of new engineering materials in the fields of industry and medical as substitutes to polyester fibers, which are materials of artificial blood vessels. We consider if various gel materials including such high-strength gels are 3D-printable, many new soft and wet systems will be developed since the most intricate shape gels can be printed regardless of the quite softness and brittleness of gels. Recently we have tried to develop an optical 3D gel printer to realize the free-form formation of gel materials. We named this apparatus Easy Realizer of Soft and Wet Industrial Materials (SWIM-ER). The SWIM-ER will be applied to print bespoke artificial organs, including artificial blood vessels, which will be possibly used for both surgery trainings and actual surgery. The SWIM-ER can print one of the world strongest gels, called Double-Network (DN) gels, by using UV irradiation through an optical fiber. Now we also are developing another type of 3D gel printer for foods, named E-Chef. We believe these new 3D gel printers will broaden the applications of soft-matter gels.
(3-Mercaptopropyl)trimethoxysilane-derived Porous Gel Monolith via Thioacetal Reaction-Assisted Sol-Gel Route
Energy Technology Data Exchange (ETDEWEB)
Ito, S; Nishi, M; Kurahashi, T; Matsubara, S; Shimotsuma, Y; Miura, K; Hirao, K [Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto-Daigaku-Katsura, Nishikyo-ku, Kyoto 615-8510 (Japan); Kanamori, K; Nakanishi, K, E-mail: email@example.com [Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa, Sakyo-ku, Kyoto 606-8502 (Japan)
Porous gel monolith was synthesized by reacting (3-mercaptopropyl)trimethoxysilane (MPTMS) with acetone on acidic conditions. It is known that MPTMS itself is difficult to turn into gel on acidic conditions and instead oligomers are obtained owing to the large mercaptopropyl group. In our system, the gels were obtained since acetone worked as a cross-linker via thioacetal reaction. Additionally, Au ions were selectively adsorbed on the obtained gel. When an obtained white gel was soaked in a chloroauric acid solution, the gel turned brown and was getting dark depending on the soaked time; on the other hand, the color of the solution turned from yellow to colorless.
Growth of antimony sulphoiodide in gel
Raman, G.; Gnanam, F. D.; Ramasamy, P.
The conditions for growing single crystals of SbSI in sodium silicate gel at room temperature have been investigated in detail. The SbSI crystals grow in the needle shape. The effect of pH on the growth of SbSI has also been discussed.
Matching Two-dimensional Gel Electrophoresis' Spots
DEFF Research Database (Denmark)
Dos Anjos, Anto?nio; AL-Tam, Faroq
This paper describes an approach for matching Two-Dimensional Electrophoresis (2-DE) gels' spots, involving the use of image registration. The number of false positive matches produced by the proposed approach is small, when compared to academic and commercial state-of-the-art approaches. This article contributes to solving one of the greatest bottlenecks in the 2-DE analysis pipeline.
Electrophoretic Porosimetry of Sol-Gels
Snow, L. A.; Smith, D. D.; Sibille, L.; Hunt, A. J.; Ng, J.; Rose, M. Franklin (Technical Monitor)
It has been hypothesized that gravity has an effect on the formation and resulting microstructure of sol-gels. In order to more clearly resolve the effect of gravity, pores may be non-destructively analyzed in the wet gel, circumventing the shrinkage and coarsening associated with the drying procedure. We discuss the development of an electrophoretic technique, analogous to affinity chromatography, for the determination of pore size distribution and its application to silica gels. Specifically a monodisperse charged dye is monitored by an optical densitometer as it moves through the wet gel under the influence of an electric field. The transmittance data (output) represents the convolution of the dye concentration profile at the beginning of the run (input) with the pore size distribution (transfer function), i.e. linear systems theory applies. Because of the practical difficulty in producing a delta function input dye profile we prefer instead to use a step function. Average pore size is then related to the velocity of this dye front, while the pore size distribution is related to the spreading of the front. Preliminary results of this electrophoretic porosimetry and its application to ground and space-grown samples will be discussed.
Sol-Gel Derived Hafnia Coatings
Feldman, Jay D.; Stackpoole, Mairead; Blum, Yigal; Sacks, Michael; Ellerby, Don; Johnson, Sylvia M.; Venkatapathy, Ethiras (Technical Monitor)
Sol-gel derived hafnia coatings are being developed to provide an oxidation protection layer on ultra-high temperature ceramics for potential use in turbine engines (ultra-efficient engine technology being developed by NASA). Coatings using hafnia sol hafnia filler particles will be discussed along with sol synthesis and characterization.
Sol-Gel Synthesis Of Aluminoborosilicate Powders
Bull, Jeffrey; Leiser, Daniel; Selvaduray, Guna
Application of sol-gel process to synthesis of aluminoborosilicate powders shows potential for control of microstructures of materials. Development of materials having enhanced processing characteristics prove advantageous in extending high-temperature endurance of fibrous refractory composite insulation made from ceramic fibers.
Simple Cloud Chambers Using Gel Ice Packs
Kamata, Masahiro; Kubota, Miki
Although cloud chambers are highly regarded as teaching aids for radiation education, school teachers have difficulty in using cloud chambers because they have to prepare dry ice or liquid nitrogen before the experiment. We developed a very simple and inexpensive cloud chamber that uses the contents of gel ice packs which can substitute for dry…
Thermal Decomposition Characteristics of ADU Gel Spheres
International Nuclear Information System (INIS)
HTGR nuclear fuel uses a modified sol.gel GSP (Gel Supported Precipitation) method, which is a wet method used in most countries. ADU(Ammonium DiUranate) gel particles fabricated in this way pass through thermal treatments and become final UO2 microspheres. The washing characteristics such as washing volume, duration, and times during AWD(ageing, washing and drying) process after the spherical ADU gel particles preparation by the GSP method was studied. The VHTR (Very High Temperature Gas Reactor) is one of the reactor concepts in the Gen IV International Collaboration. Unlike light water reactor currently in use in Korea, a HTGR actually functions as a gas cooled reactor where the high temperature heat generated from nuclear fission in a reactor is cooled by He gas, with uranium dioxide (UO2 is globally used) used as fuel for the nuclear fission. Generally, nuclear fuel used in a HTGR is fabricated into a TRISO (TRi.ISOtropic) structure that can prevent the leakage of nuclear fission products at high temperatures
Cell viability in a wet silica gel.
Nieto, Alejandra; Areva, Sami; Wilson, Timothy; Viitala, Reeta; Vallet-Regi, Maria
A modified two-step sol-gel route using silicon ethoxide (TEOS) has been used to synthesize amorphous sol-gel-derived silica, which has been successfully used as a cell encapsulation matrix for 3T3 mouse fibroblasts and CRL-2595 epithelial cells due to its non-toxicity. The sol-gel procedure comprised a first, low pH hydrolysis step, followed by a neutral condensation-gelation step. A high water-to-TEOS ratio and the addition of d-glucose as a porogen and source of nutrients were chosen to minimize silica dissolution and improve the biocompatibility of the process. Indeed, the cell integrity in the encapsulation process was preserved by alcohol removal from the starting solution. Cells were then added in a buffered medium, causing rapid gelation and entrapment of the cells within a randomly structured siloxane matrix in the shape of a monolith, which was maintained in the wet state. MTT and alamarBlue assays were used to check the cytotoxicity of the silica gels and the viability of entrapped cells at initial times in contact with silica. To improve cell attachment, cell clumping experiments - where groups of cells were formed - were designed, rendering improved viability. The obtained materials are therefore excellent candidates for designing tissue-culture scaffolds and implantable bioreactors for biomedical applications. PMID:19481618
Driven Polymer Translocation into a Crosslinked Gel
Sean, David; Slater, Gary
In a typical polymer translocation setup, a thin membrane is used to separate two chambers and a polyelectrolyte is driven by an electric field to translocate from one side of the membrane to the other via a small nanopore. However, the high translocation rate that results from the forces required to drive this process makes optical and/or electrical analysis of the translocating polymer challenging. Using coarse-grained Langevin Dynamics simulations we investigate how the translocation process can be slowed down by placing a crosslinked gel on the trans-side of the membrane. Since the driving electric field is localized in the neighborhood of the nanopore, electrophoretic migration is only achieved by a ``pushing'' action from the polymer segment residing in the nanopore. For the case of a flexible polymer we find that the polymer fills the gel pores via multiple ``herniation'' processes, whereas for a semi-flexible chain in a tight gel there are no hernias and the polymer follows a smooth curvilinear path. Moreover, for the case of a semi-flexible polymer the gel makes the translocation process more uniform by reducing the acceleration at the end of the process.
Sol-gel Application in the Environment.
Czech Academy of Sciences Publication Activity Database
Kaštánek, František; Šolcová, Olga; Maléterová, Ywetta
Maribor : Univerza v Mariboru, 2013. [Nanofuture. Maribor (SI), 03.02.2013-07.02.2013] R&D Projects: GA TA ?R TA01020804 Institutional support: RVO:67985858 Keywords : sol-gel methods * biosenzors * environment monitoring Subject RIV: CI - Industrial Chemistry, Chemical Engineering
Optical bonding with fast sol-gel
Gvishi, R.; Pokrass, M.; Strum, G.
We investigate here the properties of fast sol-gel for optical bonding. The precursors of the fast sol-gel material are organically modified alkoxides generating a transparent hybrid (organic-inorganic) substance with silica glass-like properties whose index of refraction can be modified by the addition of various metal-oxides. The fast sol-gel method consists of rapid fabrication of a viscous resin and its subsequent dilution for long shelf life use. This material, when used as an adhesive offers the option of either a thermal or UV curing procedure. We demonstrate a bonding strength of ~ 10 MPa when a 15 ?m layer is applied between two glass elements. The bonding remained stable after an extensive -40°C - 120°C temperature cycling with minimal residual solvent evaporation at 150°C. The fast sol-gel material was tested for optical bonding between silica bulks, between silica bulk and silicon wafers and as an adhesive in silica fibre couplers.
Staining and Imaging an Agarose Gel
Hinkley, Craig
This video from CUNY Kingsborough Community College shows the process of staining and imaging an agarose gel. The video describes the process step by step and would be easy to replicate in a laboratory setting. Running time for the video is 3:18.
Preparation for Pouring an Agarose Gel
Hinkley, Craig
This video from CUNY Kingsborough Community College describes the technique of preparing to pour an Agarose Gel. The video describes the process step by step and would be easy to replicate in a laboratory setting. Running time for the video is 3:22.
Bioactive nanocrystalline sol-gel hydroxyapatite coatings.
Chai, C S; Ben-Nissan, B
Sol-gel technology offers an alternative technique for producing bioactive surfaces for improved bone attachment. Previous work indicated that monophasic hydroxyapatite coatings were difficult to produce. In the present work hydroxyapatite was synthesized using the sol-gel technique with alkoxide precursors and the solution was allowed to age up to seven days prior to coating. It was found that, similar to the wet-chemical method of hydroxyapatite powder synthesis, an aging time is required to produce a pure hydroxyapatite phase. A methodology that has been successfully used to produce nanocrystalline hydroxyapatite thin film coatings via the sol-gel route on various substrates including alumina, Vycor glass, partially stabilized zirconia, Ti-6Al-4V alloy and single crystal MgO is described. Coatings produced on MgO substrates were characterized by X-ray diffraction and atomic force microscopy, while the analogous gels were examined with thermogravimetric and differential thermal analyses. The coatings were crack free and the surface was covered with small grains, of approximately 200 nm in size for samples fired to 1000 degrees C. Coating thickness varied between 70 and 1000 nm depending on the number of applied layers. PMID:15348113
Encapsulation of nanoclusters in dried gel materials via an inverse micelle/sol gel synthesis
Martino, Anthony (Albuquerque, NM); Yamanaka, Stacey A. (Dallas, TX); Kawola, Jeffrey S. (Albuquerque, NM); Showalter, Steven K. (Albuquerque, NM); Loy, Douglas A. (Albuquerque, NM)
A dried gel material sterically entrapping nanoclusters of a catalytically active material and a process to make the material via an inverse micelle/sol-gel synthesis. A surfactant is mixed with an apolar solvent to form an inverse micelle solution. A salt of a catalytically active material, such as gold chloride, is added along with a silica gel precursor to the solution to form a mixture. To the mixture are then added a reducing agent for the purpose of reducing the gold in the gold chloride to atomic gold to form the nanoclusters and a condensing agent to form the gel which sterically entraps the nanoclusters. The nanoclusters are normally in the average size range of from 5-10 nm in diameter with a monodisperse size distribution.
Interaction between Crosslinked Polyelectrolyte Gels and Oppositely Charged Surfactants
Nilsson, Peter
The interactions between anionic, crosslinked gels and cationic surfactants have been investigated. When exposed to oppositely charged surfactant, the gel collapses into a dense complex of polyion and micelles. During deswelling, the gel phase separates into a micelle-rich, collapsed surface phase, and a swollen, micelle-free core, both still part of the same network. As more surfactant is absorbed, the surface phase grows at the expense of the core, until the entire gel has collapsed. Polyac...
Gel-forming reagents and uses thereof for preparing microarrays
Golova, Julia (Burr Ridge, IL); Chernov, Boris (Burr Ridge, IL); Perov, Alexander (Woodridge, IL)
New gel-forming reagents including monomers and cross-linkers, which can be applied to gel-drop microarray manufacturing by using co-polymerization approaches are disclosed. Compositions for the preparation of co-polymerization mixtures with new gel-forming monomers and cross-linker reagents are described herein. New co-polymerization compositions and cross-linkers with variable length linker groups between unsaturated C.dbd.C bonds that participate in the formation of gel networks are disclosed.
Effect of Electron beam on Prepared HAP-Gel Composition
Naima A. El Gendy*,Tawfik M. S.**, and Asma M. Nour
Background: Polyvinyl alcohol liquid PVAl was used as the organic carrier for Hydroxylapatite-gel (Hap-gel) composite. PVAl has the ability to form a nano- hydroxylapatite polyvinyl alcohol composite gel which has a wide range of uses in different environmental and medical applications. Prepared Hap-gel is known to have a very similar composition to human bone and is used as a substitute for bones in compound fractures and artificial dentures. Matreia and Methods: In this work prepared H...
Gel dosimetry for HDR Brachytherapy 3-D distribution through MRI
International Nuclear Information System (INIS)
Gel dosimetry using MRI is increasingly being utilized in contemporary literature. In our work we investigated the calibration of an acrylic gel by means of imaging with magnetic resonance and its application to the dose measurement in a 3D distribution 192Ir HDR brachytherapy treatment. Early gel dosimetry used Fricke gels and T1 relaxation time. In 2001 Fong et al. introduced a new normoxic gel known as ''MAGIC'' gel, the main components of which are Metacrylic Acid (polymer) and Hydroquinone ( polymerizing inhibitor). For this material, the evidence of radiation dose is indicated by a change in the T2 relaxation time on an MR image. Later studies varied concentrations of the MAGIC gel components in order to observe its effect and the behavior of the gel sensitivity, for magnetic fields over 0.5 T. In the 1980s a series of studies on dose quantification using magnetic resonance images and Fricke gels were performed by evaluating T1 signal through means of an Inversion Recovery technique. Polymer gels have been developed to avoid the adverse effects of oxygen that plague Fricke gels. Normoxic gels have a component which helps to capture the oxygen dissolved in the gel (MAGIC). For these type of gels, measurements of T2 are made using a Spin-Echo technique. For both groups of gels, the Relaxativity compared to either T1 or T2 varies linearly with the absorbed dose. Novotny et al. has obtainedabsorbed dose. Novotny et al. has obtained a dose response curve for BANG-2 gel showing a linear relationship of 1/T2 vs D[Gy]. In the work presented here we tested and found the same linear relation between spin-spin relaxation (R2=1/T2) versus dose up to 8.0Gy
Gel-based and gel-free quantitative proteomics approaches at a glance
Cosette Abdallah; Eliane Dumas-Gaudot; Jenny Renaut; Kjell Sergeant
Two-dimensional gel electrophoresis (2-DE) is widely applied and remains the method of choice in proteomics; however, pervasive 2-DE-related concerns undermine its prospects as a dominant separation technique in proteome research. Consequently, the state-of-the-art shotgun techniques are slowly taking over and utilising the rapid expansion and advancement of mass spectrometry (MS) to provide a new toolbox of gel-free quantitative techniques. When coupled to MS, t he shotgun proteomic pipeline...
Nanoscale Silicon Dioxide Prepared by Sol-Gel Process
Hui Gao; Junling Yang
Nanoscale silicon dioxide has been prepared with tetraethyl orthosilicate (TEOS) by sol-gel process. The optimum process conditions have been obtained by investigating the effect of formulation, temperature, catalyst and etc. on its gel morphology, gel time, and particle size.
Hydroxyapatite incorporated into collagen gels for mesenchymal stem cell culture.
Laydi, F; Rahouadj, R; Cauchois, G; Stoltz, J-F; de Isla, N
Collagen gels could be used as carriers in tissue engineering to improve cell retention and distribution in the defect. In other respect hydroxyapatite could be added to gels to improve mechanical properties and regulate gel contraction. The aim of this work was to analyze the feasibility to incorporate hydroxyapatite into collagen gels and culture mesenchymal stem cells inside it. Human bone marrow mesenchymal stem cells (hMSC-BM) were used in this study. Gels were prepared by mixing rat tail type I collagen, hydroxyapatite microparticles and MSCs. After polymerization gels were kept in culture while gel contraction and mechanical properties were studied. In parallel, cell viability and morphology were analyzed. Gels became free-floating gels contracted from day 3, only in the presence of cells. A linear rapid contraction phase was observed until day 7, then a very slow contraction phase took place. The incorporation of hydroxyapatite improved gel stability and mechanical properties. Cells were randomly distributed on the gel and a few dead cells were observed all over the experiment. This study shows the feasibility and biocompatibility of hydroxyapatite supplemented collagen gels for the culture of mesenchymal stem cells that could be used as scaffolds for cell delivery in osteoarticular regenerative medicine. PMID:23798652
Study of nuclear glasses alteration gel and synthesis of some model gels
International Nuclear Information System (INIS)
This work deals with the general problem of alteration of the reference nuclear glass R7T7. Attention is paid particularly to the altered layer formed at the glass surface during alteration process. In opposition to previous works, related essentially to glass dissolution kinetics based on chemical analyses of lixiviated elements, this thesis deals with alteration problems through structural studies of the reference glass and derived gel. This approach allows the determination of mechanisms for the gel formation and a better understanding of the behaviour of glasses towards lixiviation. Both approaches appeared complementary. Based on several spectroscopic techniques, this work showed the particular role of cations such as calcium, zirconium and iron. Studies of silica-based synthetic gels showed the synergic effect of formers cation and of one highly coordinated cation. The variation of the wavenumber related to Si-O-Si asymmetric stretching vibration can be correlated to O/Si ratio for ternary systems Si/Na/Zr. On the contrary, the Si losses of the materials depend on the number of non-bridging oxygen atoms. In the perspective of long-term behaviour, the alteration gel presents better characteristics than initial glass. It is therefore a highly stable material in static conditions. In the same way, synthetic gels are materials with very low solubilities (much lower than the alteration gel) and could be used as confining matrices. (authors). refs., 71 figs., 37 tabs
21 CFR 878.3540 - Silicone gel-filled breast prosthesis.
...Identification —(1) Single-lumen silicone gel-filled breast prosthesis. A single-lumen silicone gel-filled...with injectable silicone gel at time of implantation. The device...female breast. (2) Double-lumen silicone gel-filled...
Study on propartis of coal extracts. Solvent gel film; Sekitan chushutsubutsu. Yobai gel maku no seijo no kento
Energy Technology Data Exchange (ETDEWEB)
Isoda, S.; Takanohashi, T.; Iino, M. [Tohoku University, Sendai (Japan). Institute for Chemical Reaction Science
Coal extracts-solvent gel films are prepared by evaporation of N-methyl-2-pyrrolidinone(NMP) from coal extract solution in NMP. FR-IR measurement was carried out to investigate the physical state of NMP in the gel films. A significant amount of NMP were found to form hydrogen bonds with coal in the gel film. Temperature dependence of viscoelasticity was investigated to clarify cross-linking structure of the gel. 2 refs., 9 figs.
Forma nervosa da artrite-encefalite caprina / Nervous form of caprine arthritis-encephalitis
Scientific Electronic Library Online (English)
Karla Moraes Rocha, Guedes; Vanessa da Silva, Mustafa; Pedro Miguel Ocampos, Pedroso; David, Driemeier; Fábio Henrique Bezerra, Ximenes; Cristiano Barros de, Melo; José Renato Junqueira, Borges; Márcio Botelho de, Castro.
Full Text Available Săo descritos dois casos de caprinos, fęmeas, mestiços da raça Saanen de dois meses de idade com sinais clínicos de paresia de membros posteriores, incoordenaçăo, dificuldade respiratória e caquexia, que foram submetidos ŕ eutanásia, devido ao prognóstico desfavorável. Na necropsia, observou-se cong [...] estăo do sistema nervoso central (SNC) e consolidaçăo pulmonar nos dois caprinos. Microscopicamente, as alteraçőes foram caracterizadas por leucoencefalomielite linfoplasmocítica multifocal, com vacuolizaçăo do neurópilo e esferoides axonais, leptomeningite, pneumonia intersticial năo supurativa no caprino A e broncopneumonia bacteriana no caprino B. O exame de imuno-histoquímica (IHQ) foi positivo para o vírus da artrite-encefalite caprina em fragmento de tálamo. A prova de imunodifusăo em gel de ágar (IDGA) foi realizada em vinte animais do rebanho de origem e dezesseis animais foram positivos. O diagnóstico da forma nervosa da infecçăo pelo vírus da artrite-encefalite caprina (CAEV) foi baseado no quadro clínico-patológico, IHQ e IDGA. Esta apresentaçăo clínica da CAE pode ser pouco comum no Brasil, mas deve ser considerada em caso de doenças neurológicas em pequenos ruminantes. Abstract in english Two cases are described of female goats, Saanen crossbreds, two months old, with clinical signs of hind limb paresis, incoordination, difficulty breathing and cachexia, which were subjected to euthanasia due to unfavorable prognosis. At necropsy it was possible to observe that there was congestion o [...] f the central nervous system (CNS) and pulmonary consolidation in both goats. Microscopic changes were characterized by multifocal lymphoplasmacytic leucoencephalomielitis, with vacuolization of neuropile and axonal spheroids, leptomeningitis, interstitial nonsupurative pneumonia in goat A and bacterial bronchopneumonia in goat B. Immunohistochemistry (IHC) was positive for the caprine arthritis - encephalitis virus in thalamus fragments. The agar gel immunodiffusion (AGID) test was performed in sera sample of twenty animals and sixteen resulted positive. Diagnosis of the nervous form of caprine arthritis-encephalitis virus (CAEV) infection was based on clinical and pathological status, IHC and AGID. This clinical presentation of CAE could be uncommon in Brazil, but must be considered in case of neurologic diseases in small ruminants.
Sol-gel Technology for Sensor Applications (Review Paper
Directory of Open Access Journals (Sweden)
N. K. Chaudhury
Full Text Available Sol-gel processes refer to the transition of predefined compositions of inorganic alkoxidesprecursors from liquid sol phase to solid gel phase. The phenomenon of sol-gel was known tomankind for more than 150 years. It is because of concerted efforts of researchers frommultidisciplinary fields, sol-gel science transformed to technology. Several products are alreadycommercially available for applications in optical coatings, nanocomposites, and public healthcare.Potential applications in the areas of biosensors and environmental monitoring are expected.Newer applications with nanotechnology appear too exciting. An attempt has been made toaddress important applications of sol-gel technology, particularly in sensing techniques fromthe defence perspective.
Local mobility and topology in gels
International Nuclear Information System (INIS)
In the first section of this two part report entitled 'Separation of the motion around cross-link points from main chain motion in network samples' by Higgins, Ma and Hall, experimental evidence for topologically dependent diffusion in gels and rubbers is presented from high resolution neutron scattering experiments on deuterium labelled model trifunctional networks which show that the junction points move more slowly than the free chain centres by a factor of about two. In the second part by Warner entitled 'The dynamics of particular points on a polymer chain', the diffusional dynamics of particular points of a polymer chain is calculated in the Rouse approximation. The points considered correspond, in the case of incoherent neutron scattering, to the proton-labelled free ends of chains, crosslinks between chains in rubbers or gels, or the central monomers in branched or star polymers. Results derived are also relevant to NMR, ESR and computer simulation experiments. (U.K.)
Switching friction with thermal- responsive gels.
Wu, Yang; Cai, Meirong; Pei, Xiaowei; Liang, Yongmin; Zhou, Feng
The thermosensitive graphene oxide (GO)/poly(N-isopropyl acrylamide) (pNIPAM) composite hydrogels are prepared, and their tribological properties in response to external stimuli are evaluated. The frictional coefficient of the hydrogels is closely related to the gel composition and ambient temperature. When the gel is in swelling state below the low critical solution temperature (LCST), it shows ultra-low friction and exhibits high friction at a shrunk state above the LCST. The huge difference of frictional coefficient under two states can be reversibly switched many times by altering the temperature. The incorporation of a nonthermal sensitive monomer into pNIPAM could change the LCST and thus the transformation point of frictional coefficient can be altered. These reversible and tunable frictional hydrogels have potential application in the design of intelligent control equipment. PMID:24249089
Fundamentals of MRI measurements for gel dosimetry
International Nuclear Information System (INIS)
In radiotherapy gel dosimetry a humanoid phantom is irradiated according to the planned treatment of a patient. This results in a three-dimensional dose distribution. In order to read-out the gel dosimeter phantom, magnetic resonance imaging (MRI) is often used. Due to specific disturbances both the spatial and the dose reliability can be compromised. It is essential that the measurement sequence is optimized and that possible imaging artifacts are compensated in such a way that the proposed spatial and dose accuracy are met. In this review, several sources of disturbances are treated and compensation strategies are proposed. A code of good practice for the read-out technique is proposed. Finally, a tool for quality control of the imaging sequence is presented
Instabilities in droplets spreading on gels
Daniels, K E; Behringer, R P; Daniels, Karen E.; Mukhopadhyay, Shomeek; Behringer, Robert P.
The surface-tension driven spreading of liquids is industrially and biologically important, and has been studied in detail on both solid and liquid substrates. Less is known about how droplet spreading is modified in the presence of a compliant substrate, a situation especially relevant to biological applications. We perform droplet-spreading experiments on gel agar, a viscoelastic material, to explore the influence of substrate on the spreading dynamics of the droplet. We find a novel branching instability with an onset that is controlled by the ratio of surface tension difference to the shear strength of the gel. The existence of a spreading morphology in which a spreading droplet becomes spatially localized has important implications for the industrial and medical application ofsurfactants.
Ordering phenomena in ABA triblock copolymer gels
DEFF Research Database (Denmark)
Reynders, K.; Mischenko, N.
Temperature and concentration dependencies of the degree of order in ABA triblock copolymer gels are discussed. Two factors can influence the ordering phenomena: the conformation of the midblocks (links of the network) and the polydispersity of the endblock domains (nodes of the network). The latter is defined by the scattering density profile (polymer chain packing) at the domain boundary: a sharp boundary corresponds to less polydisperse domains and to increased order in the arrangement of the network nodes. The structure of the network can be described in terms of a highly distorted crystalline lattice with close-packed spheres or with cubic (presumably BCC) equilibrium morphology. The appearance of the latter is never detected in the gels with a stretched conformation of the midblock.
Ordering phenomena in ABA triblock copolymer gels
International Nuclear Information System (INIS)
Temperature and concentration dependencies of the degree of order in ABA triblock copolymer gels are discussed. Two factors can influence the ordering phenomena: the conformation of the midblocks (links of the network) and the polydispersity of the endblock domains (nodes of the network). The latter is defined by the scattering density profile (polymer chain packing) at the domain boundary: a sharp boundary corresponds to less polydisperse domains and to increased order in the arrangement of the network nodes. The structure of the network can be described in terms of a highly distorted crystalline lattice with close-packed spheres or with cubic (presumably BCC) equilibrium morphology. The appearance of the latter is never detected in the gels with a stretched conformation of the midblock. (orig.)
Anion-switchable supramolecular gels for controlling pharmaceutical crystal growth
Foster, Jonathan A.; Piepenbrock, Marc-Oliver M.; Lloyd, Gareth O.; Clarke, Nigel; Howard, Judith A. K.; Steed, Jonathan W.
We describe the use of low-molecular-weight supramolecular gels as media for the growth of molecular crystals. Growth of a range of crystals of organic compounds, including pharmaceuticals, was achieved in bis(urea) gels. Low-molecular-weight supramolecular gelators allow access to an unlimited range of solvent systems, in contrast to conventional aqueous gels such as gelatin and agarose. A detailed study of carbamazepine crystal growth in four different bis(urea) gelators, including a metallogelator, is reported. The crystallization of a range of other drug substances, namely sparfloxacin, piroxicam, theophylline, caffeine, ibuprofen, acetaminophen (paracetamol), sulindac and indomethacin, was also achieved in supramolecular gel media without co-crystal formation. In many cases, crystals can be conveniently recovered from the gels by using supramolecular anion-triggered gel dissolution; however, crystals of substances that themselves bind to anions are dissolved by them. Overall, supramolecular gel-phase crystallization offers an extremely versatile new tool in pharmaceutical polymorph screening.
G-Quadruplex Guanosine Gels and Single Walled Carbon Nanotubes
Directory of Open Access Journals (Sweden)
Yuehua Yu
Full Text Available Solubilization of single walled carbon nanotubes (SWNTs in aqueous gel phases formed by reversible, G-quadruplex self-assembly of guanosine monophosphate (GMP alone or with guanosine (Guo is described. Unlike other media and methods for aqueous solubilization of SWNTs, the guanosine gels ("G-gels" are found to readily disperse high (>mg/mL concentrations of individual rather than bundled SWNTs. SWNT dispersions in GMP alone precipitate in several hours and re-form upon shaking; however, dispersions in the binary GMP/Guo gels are indefinitely stable. Increasing GMP or KCl concentration in the binary gels increased the relative abundance of large diameter and semi-conducting SWNTs. Different gel compositions also displayed different selectivities toward SWNTs of different chiralities. These results indicate a strong connection between the self-assembled G-gels and the dimensions and structures of the SWNTs that they solubilize.
Antioxidant effect of green tea on polymer gel dosimeter
Samuel, E. J. J.; Sathiyaraj, P.; Deena, T.; Kumar, D. S.
Extract from Green Tea (GTE) acts as an antioxidant in acrylamide based polymer gel dosimeter. In this work, PAGAT gel was used for investigation of antioxidant effect of GTE.PAGAT was called PAGTEG (Polyacrylamide green tea extract gel dosimeter) after adding GTE. Free radicals in water cause pre polymerization of polymer gel before irradiation. Polyphenols from GTE are highly effective to absorb the free radicals in water. THPC is used as an antioxidant in polymer gel dosimeter but here we were replaced it by GTE and investigated its effect by spectrophotometer. GTE added PAGAT samples response was lower compared to THPC added sample. To increase the sensitivity of the PAGTEG, sugar was added. This study confirmed that THPC was a good antioxidant for polymer gel dosimeter. However, GTE also can be used as an antioxidant in polymer gel if use less quantity (GTE) and add sugar as sensitivity enhancer.
Ring-Resonator/Sol-Gel Interferometric Immunosensor
Bearman, Gregory; Cohen, David
A proposed biosensing system would be based on a combination of (1) a sensing volume containing antibodies immobilized in a sol-gel matrix and (2) an optical interferometer having a ring resonator configuration. The antibodies would be specific to an antigen species that one seeks to detect. In the ring resonator of the proposed system, light would make multiple passes through the sensing volume, affording greater interaction length and, hence, greater antibody- detection sensitivity.
Biological macromolecules as gels: functional similarities.
Douzou, P.
Functional biological macromolecules arising from folding, cross-connection, and solvation of long-chain biopolymers forming three-dimensional networks can be compared to gels. Both involve identical internal competitive forces that are selectively influenced by external conditions and conspire to adjust conformations and modulate functions. In spite of important differences in size, chemical composition, polymer density, and configuration, biological macromolecules indeed manifest some of th...
Gel Evolution in Oil Based Drilling Fluids
Sandvold, Ida
Drilling fluids make up an essential part of the drilling operation. Successful drilling operations rely on adequate drilling fluid quality. With the development of new drilling techniques such as long deviated sections and drilling in ultra-deep waters, the standard of required performance of the drilling fluids continue to increase. Narrow pressure margins and low tolerance for barite sag requires accurate prediction of the gel evolution in drilling fluids. Increased knowledge of how dri...
Time-dependent strength of colloidal gels
Manley, Suliana; Davidovitch, B; Davies, N. R.; Cipelletti, L.; Bailey, A. E.; Christianson, R. J.; Gasser, U.; Prasad, V.(Indian Institute of Technology Guwahati, 781039, Guwahati, Assam, India); Segre, P. N.; Doherty, M. P.; Sankaran, S; Jankovsky, A. L.; Shiley, B.; Bowen, J; Eggers, J.
Colloidal silica gels are shown to stiffen with time, as demonstrated by both dynamic light scattering and bulk rheological measurements. Their elastic moduli increase as a power law with time, independent of particle volume fraction; however, static light scattering indicates that there are no large-scale structural changes. We propose that increases in local elasticity arising from bonding between neighboring colloidal particles can account for the strengthening of the network, while preser...
Schmidt, Helmut K.
The sol-gel process is a method for the preparation of inorganic materials and organically modified ceramics by "soft" chemistry. The possibility of adjusting the rheology of intermediates leads to products for coating procedures. As coating techniques dip, spin-on, spray, roll, and others are possible. Different applications for glasses are possible: to improve the surface properties of glass (e.g. strength) and to generate special effects or functions (optical, chemical reactivity, sensitiv...
Semiconductor Gel in Shark Sense Organs?
Fields, R. Douglas; Fields, Kyle D.; Fields, Melanie C.
Sharks can sense bioelectric fields of prey and other animals in seawater using an extraordinary system of sense organs (ampullae of Lorenzini) [9]. A recent study reported that these sense organs also enable sharks to locate prey-rich thermal fronts using a novel mode of temperature reception without ion channels. The study reported that gel extracted from the organs operates as a thermoelectric semiconductor, generating electricity when it is heated or cooled [2]. Here we report biophysical...
Adiabatic nucleation and crystallization of gels
Meyer, Erich; Zanotto, Edgar D.; Aegerter, Michel A.
Adiabatic Nucleation Theory (ANT) has been successfully applied to pure liquid metals, oxide glasses, metallic glasses and polymers. This paper shows that ANT gives an interesting correlation between the crystallization data of gels of both reluctant and good (dense) glass forming systems. For reluctant glass formers, one finds that Tch T14-. T-14 is the temperature predicted by ANT at which nucleation starts in cooling experiment...
Sol-gel coatings for optoelectronic devices
César O. Avellaneda; Macedo, Marcelo A.; Florentino, Ariovaldo O.; Aegerter, Michel A.
Nb2O5 prepared by a sol-gel process in form of coatings and aerogels are new materials which present interesting properties: (a) the coatings present electrochromic properties and exhibit a blue coloration under Li+ insertion with 100% reversible variation of the optical transmission in the visible and near infrared range between 80% and 20% and have a high chemical stability (tested up to 2000 cycles), (b) they are semiconductor and present a photoelectric effect when illuminating in the UV ...
Gel Electrophoresis of Gold-DNA Nanoconjugates
Directory of Open Access Journals (Sweden)
W. J. Parak
Full Text Available Gold-DNA conjugates were investigated in detail by a comprehensive gel electrophoresis study based on 1200 gels. A controlled number of single-stranded DNA of different length was attached specifically via thiol-Au bonds to phosphine-stabilized colloidal gold nanoparticles. Alternatively, the surface of the gold particles was saturated with single stranded DNA of different length either specifically via thiol-Au bonds or by nonspecific adsorption. From the experimentally determined electrophoretic mobilities, estimates for the effective diameters of the gold-DNA conjugates were derived by applying two different data treatment approaches. The first method is based on making a calibration curve for the relation between effective diameters and mobilities with gold nanoparticles of known diameter. The second method is based on Ferguson analysis which uses gold nanoparticles of known diameter as reference database. Our study shows that effective diameters derived from gel electrophoresis measurements are affected with a high error bar as the determined values strongly depend on the method of evaluation, though relative changes in size upon binding of molecules can be detected with high precision. Furthermore, in this study, the specific attachment of DNA via gold-thiol bonds to Au nanoparticles is compared to nonspecific adsorption of DNA. Also, the maximum number of DNA molecules that can be bound per particle was determined.
Directory of Open Access Journals (Sweden)
Prajapati SK
Full Text Available The purpose of this research is to design proniosomal gel drug delivery system of flurbiprofen in a trial to overcome the adverse effects associated with oral administration of the drug. This can be overcome by the use of vesicular drug delivery system. Encapsulation of a drug in vesicular structure can be predicted to prolong the existence of the drug in the systemic circulation and thus enhance penetration into target tissue and reduce toxicity. Due to the limited solvent system present, the proniosomes formed were the mixture of many phases of liquid crystal, viz. lamellar, hexagonal and cubic phase liquid crystals. The potential of proniosomes as a transdermal drug delivery system of flurbiprofen was investigated by encapsulating the drug in various formulations of proniosomal gel composed of various ratios of sorbitan fatty acid esters, cholesterol, prepared by coacervation-phase separation method. The formulated systems were characterized in vitro for size, vesicle count, drug entrapment, drug release profiles and vesicular stability at different storage conditions. Stability studies for proniosomal gel were carried out for 4 weeks. The method of proniosome loading resulted in an encapsulation yield of 30.6 – 75.4%. Invitro studies showed prolonged release of entrapped flurbiprofen. At refrigerated conditions, higher drug retention was observed. It is evident from this study that proniosomes are a promising prolonged delivery system for flurbiprofen and have reasonably good stability characteristics.
Sol-gel method for encapsulating molecules
Brinker, C. Jeffrey (Albuquerque, NM); Ashley, Carol S. (Albuquerque, NM); Bhatia, Rimple (Albuquerque, NM); Singh, Anup K. (San Francisco, CA)
A method for encapsulating organic molecules, and in particular, biomolecules using sol-gel chemistry. A silica sol is prepared from an aqueous alkali metal silicate solution, such as a mixture of silicon dioxide and sodium or potassium oxide in water. The pH is adjusted to a suitably low value to stabilize the sol by minimizing the rate of siloxane condensation, thereby allowing storage stability of the sol prior to gelation. The organic molecules, generally in solution, is then added with the organic molecules being encapsulated in the sol matrix. After aging, either a thin film can be prepared or a gel can be formed with the encapsulated molecules. Depending upon the acid used, pH, and other processing conditions, the gelation time can be from one minute up to several days. In the method of the present invention, no alcohols are generated as by-products during the sol-gel and encapsulation steps. The organic molecules can be added at any desired pH value, where the pH value is generally chosen to achieve the desired reactivity of the organic molecules. The method of the present invention thereby presents a sufficiently mild encapsulation method to retain a significant portion of the activity of the biomolecules, compared with the activity of the biomolecules in free solution.
Decontamination using chemical gels, electrolytical swab, abrasives
International Nuclear Information System (INIS)
Decontamination for decommissioning purposes differs from usual in-service decontamination procedures. The main factors which have to be considered in setting up decontamination procedures for nuclear installation decommissioning are: rapidity and ease of application, efficiency of decontamination, possibility of remote operation and small quantities of secondary generated wastes. The aim of this research work is to develop three decontamination methods which appear to be well adapted to dismantling. After laboratory tests where several procedures are compared, actual nuclear installation dismantling operations were performed. Among the decontamination procedures developed by CEA Cadarache, the following have been the subject of extensive studies: spraying of gels containing decontaminating agents, electropolishing with swab device and abrasive blasting. Examples of industrial applications of these three techniques which have been carried out are for these procedures: gels spraying performed on pieces coming from German BW Reactor ISAR, Brennilis Bitumization plant decontamination and dismantling, gels spraying decontamination performed on the cooling circuit of the graphite gas reactor G2 and a mechanical sodium cleaning method by abrasive blasting on SuperPhenix fuel storage drum intervessel. For each of these in-situ decontamination operations, a balance has to be made between the quantity of decontaminated metallic wastes and the amount of chemical reagent used asand the amount of chemical reagent used as well as the quantity of secondary wastes generated. (author)
Research software for radiotherapy gel dosimetry
International Nuclear Information System (INIS)
Gel dosimetry using magnetic resonance imaging is a technique which allows measurement of three-dimensional absorbed dose distributions in radiation therapy. This paper presents details of a software tool written specifically to provide facilities to perform image processing required in research and development of gel dosimetry. Collections of magnetic resonance images can be converted into either longitudinal or transverse nuclear magnetic resonance relaxation images. The conversions are accomplished by means of a pixel-by-pixel non-linear least squares fitting algorithm. Adjustments can be made to the number of parameters used in the fitting algorithm. Fundamental image manipulation tools such as window width / level display adjustment zooming, profile and region of interest tools are provided. The software has been developed using MATLAB (The MathWorks Inc., Natick, MA) running on Windows 95. User interaction is via a windows graphical user interface (GUI). Data such as statistics from regions of interest can be exported to other windows applications for further processing. Flexibility is incorporated in the GUI design by taking advantage of the developmental aspects of the MATLAB environment. Although originally designed for gel dosimetry, the software can be used in any application of MRI which requires production and manipulation of relaxation time images
Development of Stable Restructured Mango Gel
Directory of Open Access Journals (Sweden)
D.K. Das Gupta
Full Text Available Restructured mango gel was prepared by alginate texturization of mango pulp using sodium alginate, glucono-?-lactone and calcium hydrogen orthophosphate. The requisite quantities of the chemical additives were mixed, added together to the neutralized mango pulp in a mixer and allowed to set at 4°C for 16 h. The mango gel was cut into 1.5 cm cubes and stabilized by Hurdle Technology (HT through adjustment of water activity to 0.89, pH 4.4 and pasteurization in polypropylene pouches. Storage studies were carried out in foil laminate packs at three different temperatures i.e. 4°C, RT (20-33°C and 37°C and evaluated for chemical parameters, Hunter colour values as well as microbiological and organoleptic characteristics. Studies showed that HT preserved texturized mango gel could be kept in acceptable condition up to 12 months at RT and 6 months at 37°C. During storage a considerable reduction in sulphur dioxide, carotenoids and an increase in acidity were observed. Decrease in L, a, b values was also observed in all the samples stored under different temperatures. The product was also found to be microbiologically stable and safe up to 12 m.
Highly-correlated charges in polyelectrolyte gels
Sing, Charles; Zwanikken, Johannes; Olvera de La Cruz, Monica
Polyelectrolyte gels are ubiquitous in polymer physics due to their attractive combination of structural and chemical features that permit the realization of ``environmentally responsive'' systems. The conventional conceptual picture of the volume response of these systems is based on a competition between osmotic and elastic effects. We elaborate on this fundamental understanding by including ion correlations through the use of liquid-state integral equation theory. This allows for a statistical mechanical representation of the state of the system that not only surpasses traditional Poisson-Boltzmann theories but also renders structural features in a highly accurate fashion. In particular, the local ion structure is elucidated, allowing for detailed articulation of charge inversion and condensation effects in the context of gel swelling. The inclusion of correlations has a number of ramifications that become apparent, with enhanced gel collapse and excluded volume competitions that give rise to novel and ion-dependent reentrant swelling effects. We expect this rigorous theory to prove instructive in understanding any number of gelated structures, such as chromosomes or designed synthetic materials for drug delivery.
Colloid molecular weight estimation by gel chromatography/acrylamide gel electrophoresis
International Nuclear Information System (INIS)
Size or molecular weight (MW) estimation of radiolabeled collides in aqueous solutions has long been a problem. The authors have prepared several minimicroaggregated albumin colloids (m?AA) by heat denaturation of stannous-containing HSA solutions at pH 7.0, 7.5, and 8.5). The resulting colloids were labeled with Tc-99m and compared with Au-198 colloid and Tc-99m-antimony sulfide colloid (Tc-99m-Sb/sub 2/S3) by gel chromatography and gel electrophoresis. Tc-99mm-m?AA aggregated at pH 7.0 and the Au-198 colloid appeared in the external void volume of a BioRad A5.0 agarose column indicating an apparent MW of > 5 x 10/sup 6/ daltons. The pH7.5 Tc-99m-m?AA, migrated within the filtration range of the column as did a small fraction of Tc-99m-Sb/sub 2/S/sub 3/, suggesting that the MW is between 6 x 10/sup 4/ - 5 x 10/sup 6/ daltons. The Tc-99m-m?AA, aggregated at pH 8.5, had an apparent MW on gel filtration similar to that of untreated albumin, MW 6.6 x 10-/sup 4/ daltons. The mobilities of the colloids, on acrylamide disc gel electrophoresis, were consistent with the results on gel chromatography. The largest colloids, Au-198 colloid and pH 7.0 Tc-99m-m?AA, barely entered the separating gel; intermediate sized colloids, a small fraction of Tc-99m-Sb/sub 2/S/sub 3/ and pH 7.5 Tc-99m-m?AA migrated farther into the separating gel; while pH 8.5 Tc-99m-m?AA had mobility approaching that of untreated albumin. Lymphoscintigraphy studies using these colloids in animals showed the predicted, particle size-related differences in migration and clearance. The authors conclude that gel chromatography and gel electrophoresis are useful methods for estimating the apparent size of the colloidal particles
Different Applications of Rheological Techniques in Studies of Physical Gels
DEFF Research Database (Denmark)
Hvidt, SŘren
Physical gels are of both great scientific and practical interest. The cytoplasm of cells, which consists of a complex physical gel of protein filaments, is important for most of the cellular processes including cell division and cell motility. Nature has developed this complex system of associating protein filaments with the characteristic function of individual filaments. The proteins enable the cell to regulate the mechanical properties of the cell by sol-gel transition and a variety of crosslinking reactions. In the food industry texture of products are regulated by addition of gel-forming biopolymers. Physical gels are also used in the paint industry to minimize sedimentation. Delayed and controlled drug release is of importance in the pharmaceutical industry, and one way to obtain this control is to hide active components in physical gels. Two excellent reviews cover many aspects of biopolymer and physical gels [1,2]. The nature of physical gels has been debated for many years. In contrast to chemicallycrosslinked gels physical gels are often thermoreversible and small changes in e.g. temperature, pH or ionic strength may shift the system from a gel state to a sol state. Ole Kramer [3] pointed out the importance of time scales for physical gels. According to him the characteristic property of a gel is the presence of two components and a constant elastic storage modulus on time scales of 1 s or frequencies of 1 rad/s. His definition of gels relies on their rheological properties. Rheological techniques are used extensively in studies of physical gels and gelation. In the lecture some of the common techniques used in studies of gels will be addressed. Small amplitude oscillatory measurements are the most common type of measurement performed, and such measurements allow a determination of the elastic storage modulus, G', and loss modulus, G", as a function of e.g. frequency, temperature, or time. Two other techniques, which can be very useful for studies of gels, are creep and relaxation measurements. These techniques, which allow determinations of the compliance and the relaxation modulus, respectively, are particularly useful for investigating slow motions in gels and long-time properties. An example of how these different techniques have been used to investigate the rheological properties of sputum [4] will be discussed. The results demonstrate that sputum is a viscoelastic material and that both nucleic acids and actin filaments contribute to the viscoelastic properties of sputum from cystic fibrosis patients. Many simple methods have been developed over the years in industry to characterize products. The SAG test is widely used in the food industry to grade pectin samples and their ability to form gels. The test, which consists of a SAG measurement due to gravity of gels with a very precisely defined shape, is highly reproducible. However, it does not give any information about fundamental rheological properties of the pectin gels. Our attempt to understand more fundamental aspects of this test combined creep and oscillatory measurements together with finite element simulation. The results show [5] that pectin gels can be modeled as nearly ideal incompressible elastic materials, and equations connecting SAG number and the elastic storage modulus have been obtained. Solutions of tri-block copolymers of ethylene oxide and propylene oxide form micelles in water with increasing temperature due to the hydrophobic nature of poly(propylene oxide) at higher temperatures. At high concentration micelles pack in bcc structures and various other gel structures are also formed. The gel properties are dominated by repulsive interactions between micelles, and oscillatory measurements allow a determination of the repulsive potential between micelles. Oscillatory bulk modulus measurements have been used to determine the dynamics of unimer-micelle motions. The strain properties of physical gels are of major importance in many applications. When a gel is deformed with increasing strain or strain amplitudes most gels eventually
Ferramentas diagnósticas de Lentivirose de Pequenos Ruminantes: padronizaçăo da técnica de ELISA indireto / Diagnostic tools of small ruminant lentiviruses: standardization of indirect ELISA
Scientific Electronic Library Online (English)
Caliandra Bona, Nascimento; Raymundo Rizaldo, Pinheiro; Francisco Selmo Fernandes, Alves; Roberta Lomonte Lemos de, Brito; Apoliana de Sousa, Rodrigues; Ricardo Abílio, Bezerra e Silva; Ney Rômulo de Oliveira, Paula; Maria do Carmo de Souza, Batista.
Full Text Available As Lentiviroses de Pequenos Ruminantes (LVPR) incluem a Maedi-Visna (MV) em ovinos e a Artrite Encefalite Caprina (CAE). Essas enfermidades estăo difundidas no mundo e săo responsáveis por grandes perdas na produtividade destes animais. Os LVPR săo vírus RNA da subfamília Lentivirinae que causam uma [...] infecçăo persistente, sendo a detecçăo precoce uma das formas mais eficientes para limitar sua disseminaçăo no rebanho. Visando contribuir com essas questőes, este experimento foi realizado na Universidade Federal do Piauí (UFPI) em parceria com a Embrapa Caprinos e Ovinos, com o objetivo de padronizar a técnica de ensaio imunoenzimático indireto e compará-lo com a imunodifusăo em gel de agarose no diagnóstico da CAE. Foram utilizadas 696 amostras de soros de caprinos machos e fęmeas oriundas do banco de soros da Unidade de Pesquisa de LVPR do Centro de Cięncias Agrárias da UFPI. As amostras foram coletadas no período de janeiro de 2007 a março de 2010. Na padronizaçăo, verificou-se que 0,25 µg de proteína/poço, diluiçăo de 1:200 do soro e concentraçăo de 1:3.000 do conjugado anticorpo anti-IgG cabra apresentaram os melhores resultados. O ponto de corte obtido foi de 0,36. Na comparaçăo, o Imunodifusăo em Gel de Ágar (IDGA) detectou 128 (18,4%) amostras positivas, e o ELISA indireto (ELISA-i), 259 (37,2%). A sensibilidade e a especificidade do teste ELISA-i com relaçăo ao IDGA foi de 94,5% e 75,7%, respectivamente. Verificou-se maior índice de positividade em caprinos acima de seis meses (p Abstract in english The Small Ruminant Lentiviruses (SRLVs) include Maedi-Visna (MV) of sheep and Caprine Arthritis-Encephalitis (CAE). These diseases are widespread and responsible for major production losses regarding sheep and goats. The SRLV is a RNA virus of the subfamily Lentivirus genus that causes persistent in [...] fections in goats. Early detection is one of the best ways to limit its spread in the herd. To contribute to these issues, this experiment was conducted at Universidade Federal do Piauí in partnership with Embrapa Goats and Sheep, with the objective of standardizing the technique of indirect ELISA (i-ELISA) and to compare it with Immunodiffusion in Agarose Gel to diagnose Caprine Lentiviruses (LC). Six hundred ninety six serum samples were used from the University Veterinary Hospital, Universidade Federal do Piauí, from January 2007 to March 2010. Standardization showed that 0.25 µg protein/well, a 1:200 dilution of the serum and concentration of 1:3,000 of the conjugated anti-goat IgG presented the best results. It was observed that the Agar Gel Immunodiffusion (AGID) detected 128 (18.4%) positive samples, and ELISA, 259 (37.2%). The sensitivity and specificity of i-ELISA regarding AGID were 94.5% and 75.7%, respectively. A higher prevalence was observed among animals older than six months (p
Dosimetry in HDR brachytherapy with Fricke-gel layers and Fricke-gel catheters
Gambarini, G.; Carrara, M.; Negri, A.; Invernizzi, M.; Tenconi, C.; Scotti, A.; Pirola, L.; Borroni, M.; Tomatis, S.; Fallai, C.
Fricke-gel layer dosimeters (FGLD) and Fricke gel dosimetric catheters (FGDC) have been designed and tested with the aim of enquiring their suitability for HDR 192Ir brachytherapy source control and for in-vivo dose verification during treatment. Anisotropy function measurements have been carried out with FGLDs in which a thin plastic tube has been placed in for the 192Ir source insertion. FGDCs are constituted by plastic tubes (3 mm of external diameter and 13 cm of length) filled with the dosimeter-gel. Absorbed dose images and profiles were attained by means of optical analysis. Dedicated software has been developed both for achieving anisotropy function values and for obtaining reliable results in visible light absorbance measurements across the thin cylindrical dosimeters. Preparation and analysis procedures have been optimised. The results confirm that the proposed methods are very promising for HDR brachytherapy dosimetry.
Dosimetry in HDR brachytherapy with Fricke-gel layers and Fricke-gel catheters
International Nuclear Information System (INIS)
Fricke-gel layer dosimeters (FGLD) and Fricke gel dosimetric catheters (FGDC) have been designed and tested with the aim of enquiring their suitability for HDR 192Ir brachytherapy source control and for in-vivo dose verification during treatment. Anisotropy function measurements have been carried out with FGLDs in which a thin plastic tube has been placed in for the 192Ir source insertion. FGDCs are constituted by plastic tubes (3 mm of external diameter and 13 cm of length) filled with the dosimeter-gel. Absorbed dose images and profiles were attained by means of optical analysis. Dedicated software has been developed both for achieving anisotropy function values and for obtaining reliable results in visible light absorbance measurements across the thin cylindrical dosimeters. Preparation and analysis procedures have been optimised. The results confirm that the proposed methods are very promising for HDR brachytherapy dosimetry.
Investigation of the Peroxovanadate Sol-Gel Process and Characterization of the Gels
Energy Technology Data Exchange (ETDEWEB)
Craig Joseph Fontenot
In general, the peroxovanadate solution sol-gel process can be thought of as consisting of two parts: (1) the decomposition of the peroxo species and (2) cation hydrolysis leading to gelation. By controlling the synthesis conditions, both layered and amorphous compounds can be created. However, the type of water coordination observed in these gels was found to be identical no matter what the long-range order. The current work clarified many of the discrepancies found in the literature and offered much new valuable information. Highlights include the types of vanadium environments present at various stages of hydration, the role of adsorbed water, oxygen exchange from adsorbed water into the gel sites, and the ability to create metastable VMoO solid solution phases. These results could have a variety of impacts on future catalysis research.
Photosensitive YBCO gel film and its patterning by sol-gel process
International Nuclear Information System (INIS)
Acrylic acid (AA) as chemical modifier. The AA-modified YBCO gel film exhibits the photosensitivity to UV-light. The patterned YBCO film was fabricated by chemically modified sol-gel method. The YBCO precursor solution was prepared using yttrium acetate, barium acetate and copper acetate as starting material, diethylenetriamine, trifluoroacetate, acrylic acid (AA) as chemical additives, methanol as solvent. The precursor solution was modified by AA, in which the Cu2+ of Cu(OAc)2 and AA were reacted to form the photosensitive copper complex. The coated gel film using this precursor solution exhibited the photosensitivity to UV light at around 245 nm. Utilizing the photosensitivity, the patterned YBCO film with a high critical transition temperature (Tc) of 91.5 K was fabricated.
Sol-gel synthesis of hydroxyapatite; Sintese de hidroxiapatita via sol-gel
Energy Technology Data Exchange (ETDEWEB)
Zupanski, M.D.; Lucena, M.P.P.; Bergmann, C.P., E-mail: email@example.com [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil)
Hydroxyapatite (HAp) has been established as the calcium phosphate based compound with most applications in the biological field. Among the numerous techniques for synthesis of HAp, the sol-gel processing route affords great control over purity and formed phases using low processing temperatures. In addition, the sol-gel approach offers an option for homogeneous HAp coating on metal substrates, as well as the ability to generate nanocrystalline powders. In this work, the sol-gel synthesis of HAp was investigated employing triethyl phosphate and calcium nitrate tetrahydrate as phosphorous and calcium precursors, respectively. The aging effect on phase composition and powder morphology of the final product was studied in terms of temperature and aging time. The powders were studied by using X-ray diffraction, Fourier transform infrared spectroscopy, particle size distribution by laser diffraction and scanning electron microscopy. (author)
Vaginal deployment and tenofovir delivery by microbicide gels.
Gao, Y; Yuan, A; Chuchuen, O; Ham, A; Yang, K H; Katz, D F
Gels are one of the soft material platforms being evaluated to deliver topically acting anti-HIV drugs (microbicides) to the vaginal environment. For each drug, its loaded concentration, gel properties and applied volume, and frequency of dosing can be designed to optimize PK and, thence, PD. These factors also impact user sensory perceptions and acceptability. Deterministic compartmental modeling of vaginal deployment and drug delivery achieved by test gels can help delineate how multiple parameters characterizing drug, vehicle, vaginal environment, and dosing govern details of PK and PD and also gel leakage from the canal. Such microbicide delivery is a transport process combining convection, e.g., from gel spreading along the vaginal canal, with drug diffusion in multiple compartments, including gel, mucosal epithelium, and stroma. The present work builds upon prior models of gel coating flows and drug diffusion (without convection) in the vaginal environment. It combines and extends these initial approaches in several key ways, including: (1) linking convective drug transport due to gel spreading with drug diffusion and (2) accounting for natural variations in dimensions of the canal and the site of gel placement therein. Results are obtained for a leading microbicide drug, tenofovir, delivered by three prototype microbicide gels, with a range of rheological properties. The model includes phosphorylation of tenofovir to tenofovir diphosphate (which manifests reverse transcriptase activity in host cells), the stromal concentration distributions of which are related to reference prophylactic values against HIV. This yields a computed summary measure related to gel protection ("percent protected"). Analyses illustrate tradeoffs amongst gel properties, drug loading, volume and site of placement, and vaginal dimensions, in the time and space history of gel distribution and tenofovir transport to sites of its anti-HIV action and concentrations and potential prophylactic actions of tenofovir diphosphate therein. PMID:25874971
A mathematical characterization of the gel point in sol-gel transition
Bilge, A. H.; Pekcan, O.
We model the sol-gel transition in terms of Susceptible-Infected-Removed (SIR) and Susceptible-Exposed-Infected-Removed (SEIR) models and compare with experimental results. We show, numerically, that the "gel point" described as the onset of the gelation phenomena and measured experimentally, corresponds to an accumulation point of the extreme values of the derivatives of the gelation curve. We define the "critical point of a sigmoidal curve" as the limit of the points where the derivatives reach their extreme values, provided that this limit exists.
Sol-gel processing to form doped sol-gel monoliths inside hollow core optical fiber and sol-gel core fiber devices made thereby
Shaw, Harry C. (Inventor); Ott, Melanie N. (Inventor); Manuel, Michele V. (Inventor)
A process of fabricating a fiber device includes providing a hollow core fiber, and forming a sol-gel material inside the hollow core fiber. The hollow core fiber is preferably an optical fiber, and the sol-gel material is doped with a dopant. Devices made in this manner includes a wide variety of sensors.
Soroprevalence and risk factors associated to "Brucella canis" infection in dogs from Campina Grande, Paraíba Soroprevalęncia e fatores de risco associados ŕ infecçăo por Brucella canis em căes da
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Robério Macedo de Oliveira
Full Text Available The prevalence of brucellosis due to Brucella canis was investigated in dogs from Campina Grande, Paraíba, Northern region of Brazil, and the risk factors for seropositivity were also analyzed. For this purposes, 170 dogs' blood samples were collected during the rabies vaccination campaign, in September, 2003. The agar gel immunodiffusion test (AGID, by Brucella ovis lipopolysaccharides and proteins antigens, sample Reo 198, was used for serological diagnosis. The seroprevalence was 2.35% (95% CI = 0.64% - 5.91%. The epidemiological evidences showed that canine brucellosis due to Brucella canis in this area presented no association with the variables sex, age and management, however, there was statistic association between Brucella canis seropositivity and abortions occurrence.Foi investigada a soroprevalęncia de brucelose canina por Brucella canis em căes da cidade de Campina Grande, estado da Paraíba, Brasil, e realizado um estudo de possíveis fatores de riscos associados ŕ soropositividade. Foram examinadas 170 amostras de soro sangüíneo de căes colhidas durante a campanha de vacinaçăo anti-rábica animal, realizada em setembro de 2003. Para o diagnóstico sorológico da infecçăo por Brucella canis, foi empregada a prova de imunodifusăo em gel de ágar (IDGA, utilizando antígeno de lipopolissacarídeos e proteínas de Brucella ovis, amostra Reo 198. A soroprevalęncia encontrada foi de 2,35% (IC 95% = 0,64% - 5,91%. O perfil epidemiológico da doença mostrou que o agente infecta em iguais condiçőes os animais sem diferença de sexo, tipo de manejo e idade, havendo, contudo, associaçăo estatística entre soropositividade para Brucella canis e ocorręncia de abortamentos.
Anticorpos anti Brucella abortus, anti Brucella canis e anti Leptospira spp. em raposas (Pseudalopex vetulus) do semiárido paraibano, Nordeste do Brasil / Detection of anti Brucella abortus, anti Brucella canis and anti Leptospira spp. Antibodies in hoary foxes (Pseudalopex vetulus) from semi-arid of Paraiba state, Northeastern region of Brazil
Scientific Electronic Library Online (English)
Sérgio Santos de, Azevedo; Maria Luana Cristiny Rodrigues, Silva; Carolina de Sousa Américo, Batista; Albério Antônio de Barros, Gomes; Sílvio Arruda, Vasconcellos; Clebert José, Alves.
Full Text Available O objetivo do presente trabalho foi determinar a ocorręncia de anticorpos anti Brucella abortus, anti Brucella canis e anti Leptospira spp. em raposas (Pseudalopex vetulus). Para tanto, foram utilizadas 60 raposas atropeladas em rodovias no semiárido da Paraíba, Nordeste do Brasil. Para a detecçăo d [...] e anticorpos anti Brucella abortus, o teste do antígeno acidificado tamponado (AAT) foi empregado como teste de triagem, e a prova do 2-mercaptoetanol foi empregada como método confirmatório. Para o diagnóstico sorológico das infecçőes por Brucella canis e Leptospira spp., foram utilizados os testes de imunodifusăo em gel de agar (IDGA) e soroaglutinaçăo microscópica, respectivamente. Todas as amostras foram negativas na pesquisa de anticorpos anti Brucella canis e anti Leptospira spp. Das 60 raposas testadas, 16 (26,6%) foram positivas para anticorpos anti Brucella abortus no teste de AAT, e quatro (6,7%) amostras foram confirmadas no teste de 2-mercaptoetanol, sendo duas amostras com título 100 e duas com título 50. Abstract in english The aim of this research was to determine the occurrence of anti Brucella abortus, anti B. canis and anti Leptospira spp. antibodies in foxes (Pseudalopex vetulus). Sixty road-killed wild foxes from semi-arid of Paraiba state, Northeastern region of Brazil, were used. For the detection of anti B. ab [...] ortus antibodies, the buffered plate agglutination test (BPAT) was applied as a screening method and the 2-mercaptoethanol test as a confirmatory method. For serological diagnosis of infections by B. canis and Leptospira spp., the agar gel immunodiffusion test (AGID) and the microscopic agglutination test (MAT) were used, respectively. All samples were negative for anti B. canis and anti Leptospira spp. antibodies. Of the 60 foxes tested, 16 (26.6 %) were positive for anti B. abortus antibodies at BPAT, four (6.7%) samples were confirmed in the 2-mercaptoethanol test, and two samples presented titer 100 and two titer 50.
Estudio serológico de fiebre aftosa y brucelosis en rebańos mixtos de camélidos y ovinos en la ecorregión de serranía en Apolobamba, La Paz - Bolivia / Foot and mouth disease and brucellosis serological survey in mixed herds of camelids and sheep in the highlands of Apolobamba eco-region, La Paz - Bolivia
Scientific Electronic Library Online (English)
L. Fabián, Beltrán-Saavedra S; Herminio, Ticona Ch; Rodolfo, Nallar G; José Luis, Gonzáles R.
Full Text Available El objetivo del presente estudio fue determinar niveles serológicos de anticuerpos contra fiebre aftosa y brucelosis en rebańos mixtos de alpacas y ovejas en cuatro comunidades de la ecorregión serranía en el Área Natural de Manejo Integrado Nacional Apolobamba, La Paz - Bolivia, colindante con Perú [...] . Se colectaron 99 muestras de sangre de alpacas y 42 de ovinos de ambos sexos y edad diversa. Las muestras se procesaron mediante la prueba de inmunodifusión en gel agar para detectar anticuerpos VIA contra el virus de la fiebre aftosa y las pruebas de Aglutinación Rápida en Placa (prueba tamiz) y ELISA de competición (c-ELISA) (prueba confirmativa) para la detección de anticuerpos contra cepas lisas de Brucella sp. No se detectó anticuerpos contra fiebre aftosa o brucelosis. Abstract in english The objective of the present study was to determine serological levels of antibodies against foot and mouth disease (FMD) and brucellosis in mixed herds of alpacas and sheep in four communities of the highland ecorregion of the Apolobamba Protected Area (National Integrated Management Natural Area - [...] ANMIN), La Paz - Bolivia, bordering with Peru. Blood samples of 99 alpacas and 42 sheep of different sex and ages were collected. Plasma samples were tested for the detection of VIA antibodies against FMD virus using the agar gel immunodiffusion test (AGID-VIA) and for the detection of antibodies against smooth strains of Brucella spp. using a plate agglutination test as screening and a competitive ELISA (c-ELISA) as a confirmatory test. The results of the study showed no seropositive reactors for FMD or brucellosis.
Encapsulation of biological species in sol-gel matrices
International Nuclear Information System (INIS)
Two examples are given of the gelation of silica sols containing bio catalysts, resulting in their encapsulation in porous matrices. Urease was encapsulated in gels made from a mixture of TMOS and alkyltrimethoxysilane. Enzyme activities, monitored by measuring the rate of production of ammoniacal nitrogen as urea was decomposed, ranged up to 60% of that of the unencapsulated species. Anaerobic sulphate-reducing bacteria were encapsulated in a gel produced from colloidal silica, thus avoiding contact with alcohol. The detection of H2S produced in the doped gel indicated that the bacteria were able to continue normal metabolic function within the gel matrix. A gel initially doped with ? 5 x 105 cells cm-3, exhibited an optimum sulphate reduction rate of 11 ug h-1 cm-3; this reduction rate was quickly re-established after storage of the gel for 14 weeks. Copyright (2000) The Australian Ceramic Society
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A.P. Patil*, A.A. Tagalpallewar, G.M. Rasve, A.V. Bendre, P.G. Khapekar
Full Text Available The ophthalmic in-situ gels now days proved an palpable sustained drug delivery in various eye diseases. The formulation of in-situ gels for eye which carries the advantages like easy for administration, reduces frequency of dose and improves patient compliance. The formation of in-situ gels depends on phase transition system or sol-gel transition system. The formulation approaches like temperature intonation, pH change and presence of ions from which the drug gets released in a sustained and controlled manner are utilised for in-situ gels. Various polymers that are used for the formulation of in-situ gels include chitosan, Pluronic F-127, poly-caprolactone, gellan gum, alginic acid, xyloglucan, pectin etc.
Nonlinear elasticity and cavitation of a triblock copolymer gel.
Hashemnejad, Seyed Meysam; Kundu, Santanu
Polymer gels are subjected to large-strain deformation during their applications. The gel deformation at large-strain is non-linear and can often lead to failure of the material. Here, we report the large-strain deformation behavior of a physically cross-linked, swollen triblock copolymer gel, which displays unique strain-stiffening response at large-strain. Investigations were performed using large amplitude oscillatory shear (LAOS) and custom developed cavitation rheology techniques. The Gent constitutive equation, which considers finite extensibility of midblock, was fitted with the LAOS data, thereby, linking the estimated parameters from LAOS analysis to the structure of the gel. The pressure responses obtained from the cavitation experiments were modeled using neo-Hookean and Gent constitutive equations. Our results capture the failure behavior of a gel with finite chain extensibility, initiated from a defect within the gel. PMID:25915797
Produçăo e padronizaçăo dos antígenos de Paracoccidioides brasiliensis (Pb), Histoplasma capsulatum (Hc) e Aspergillus fumigatus (Af) para uso no imunodiagnóstico: comparaçăo entre as técnicas de imunodifusăo e imunoeletroosmoforese / Production and standardization of Paracoccidioides brasiliensis, Histoplasm capsulatum and Aspergillus fumigatus antigens to be used in immunodiagnosis: comparison between immunodiffusion and immunoelectrophoresis technics
Scientific Electronic Library Online (English)
Maria de Fátima, Ferreira-da-Cruz; Bernardo, Galvăo-Castro; Bodo, Wanke.
Full Text Available Foram produzidos antígenos solúveis de P. brasiliensis, H. capsulatum e A. fumigatus e padronizados nas técnicas de imunodifusăo dupla (IDD) e imunoeletroosmoforese (IEOF). A especificidade dos antígenos foi testada utilizando-se 96 soros de pacientes com paracoccidioidomicose, histoplasmose, asperg [...] ilose, candidíase sistęmica, esporotricose, tuberculose, neoplasia pulmonar, leishmaniose tegumentar e visceral e em 18 indivíduos sadios. Na IDD, a especificidade foi de 100% usando-se como critério de positividade linhas de precipitaçăo com identidade total com soro de referęncia. Entretanto na IEOF, a especificidade variou de acordo com o antígeno testado, sendo observadas reaçőes cruzadas com antígeno de P. brasiliensis frente a soros de pacientes com histoplasmose (16,7%) e leishmaniose tegumentar (10%) e com antígeno de H. capsulatum frente a soros de pacientes com paracoccidioidomicose (31,8%) e leishmaniose tegumentar (10%). Ambas as técnicas mostraram a mesma sensibilidade para o sorodiagnóstico de paracoccidioidomicose, histoplasmose e aspergilose, respectivamente 100%, 83,3% e 100%. A grande sensibilidade e especificidade da IDD observadas nos soros desses pacientes, aliadas ŕ fácil reprodutibilidade e baixo custo, fazem esta técnica muito apropriada como procedimento de rotina, para a triagem de pacientes sintomáticos respiratórios. Abstract in english Soluble antigens (Ag) from Paracoccidioides brasiliensis, Histoplasma capsulatum and Aspergillus fumigatus were prepared and standardized by double immunodiffusion (DID) and immunoelectroosmophoresis (IEOP). No difference in sensitivity was observed between the two techniques; 100% of standard patie [...] nt sera were positive with P. brasiliensis and A. fumigatus Ag and 83.3% were positive with H. capsulatum Ag. The specificity of the tests was verified testing 96 sera from patients with paracoccidioidomycosis, histoplasmosis, systemic candidiasis, sporotrichosis, tuberculosis, lung cancer, visceral or cutaneous leishmaniasis and 18 sera from healthy individuals. All the three antigens were 100% specific with the DID (using the identification pattern indicated by the confluence of test serum with standard serum precipitin lines as a positive criterium). However in the IEOP, the specificity varied with each Ag. Positive reactions with P. brasiliensis Ag were observed in 16.7% of histoplasmosis sera and in 10% of cutaneous leishmaniasis sera. On the other hand 31.8% of paracoccidioidomycosis and 10% of cutaneous leishmaniasis sera reacted with H. capsulatum Ag. The high sensitivity and specificity of the DID test, its easy reproducibility and low cost, led us to consider it highly appropriate as a routine procedure for the screening of patients with respiratory infections.
Screening of mucoadhesive vaginal gel formulations
Scientific Electronic Library Online (English)
Ana Ochoa, Andrade; María Emma, Parente; Gastón, Ares.
Full Text Available O planejamento racional de formulaçőes para a liberaçăo vaginal de fármacos requer atençăo especial ŕs propriedades do veículo, que otimizem o revestimento e a retençăo vaginal. O objetivo do presente trabalho foi realizar uma triagem de géis vaginais mucoadesivos formulados com carbomero ou carrage [...] nina em combinaçăo binária com um segundo polímero (carbomero, goma guár ou xantana). Os géis foram caracterizados usando estudos in vitro de aderęncia, espalhabilidade e potencial de vazamento, bem como mediçőes reológicas (testes de varredura de tensăo e frequęncia) e o efeito de diluiçăo com fluido vaginal simulado (SVF) na espalhabilidade. Os resultados foram analisados utilizando a análise de variância e de fator múltiplo. A combinaçăo de polímeros reforçou a adesăo de ambos os agentes gelificantes primários, carbomero e carragenina. Do ponto de vista reológico todas as formulaçőes apresentaram comportamento semelhante, predominantemente elástico e caracterizado por valores de tangente de perda bem abaixo de 1. Năo se encontrou correlaçăo entre as mediçőes reológicas e o comportamento de adesăo. Os géis de carbomero e carragenina contendo o maior porcentual de goma xantana apresentaram melhor mucoadesăo e espalhabilidade, menor potencial de vazamento e maior resistęncia ŕ diluiçăo in vitro. Os resultados positivos obtidos com géis de carragenina-goma xantana podem incentivar o uso de adjuvantes biocompatíveis naturais na composiçăo dos produtos vaginais, um campo de formulaçăo atualmente sob o domínio de produtos sintéticos. Abstract in english Rational design of vaginal drug delivery formulations requires special attention to vehicle properties that optimize vaginal coating and retention. The aim of the present work was to perform a screening of mucoadhesive vaginal gels formulated with carbomer or carrageenan in binary combination with a [...] second polymer (carbomer, guar or xanthan gum). The gels were characterised using in vitro adhesion, spreadability and leakage potential studies, as well as rheological measurements (stress and frequency sweep tests) and the effect of dilution with simulated vaginal fluid (SVF) on spreadability. Results were analysed using analysis of variance and multiple factor analysis. The combination of polymers enhanced adhesion of both primary gelling agents, carbomer and carrageenan. From the rheological point of view all formulations presented a similar behaviour, prevalently elastic and characterised by loss tangent values well below 1. No correlation between rheological and adhesion behaviour was found. Carbomer and carrageenan gels containing the highest percentage of xanthan gum displayed good in vitro mucoadhesion and spreadability, minimal leakage potential and high resistance to dilution. The positive results obtained with carrageenan-xanthan gum-based gels can encourage the use of natural biocompatible adjuvants in the composition of vaginal products, a formulation field that is currently under the synthetic domain.
Stimuli responsive polymer gels for sensing applications
Kavanagh, Andrew
This chapter (3) is based on simplifying the design template of an optical sensor through the multifunctionality imparted on it by an IL. The IL simplified polymer gel is termed an optode within this chapter as (a) it is prepared the same manner as optodes, (b) the IL performs many of the same functions as previous materials used in optode design and (c) the analyte or ion movement between the aqueous and organic phases follows the same convention for optodes. The 2-component optode membr...
Pulsed field gel electrophoresis for dairy propionibacteria.
Chuat, Victoria; de Freitas, Rosangela; Dalmasso, Marion
Pulsed field gel electrophoresis (PFGE) is a technique using alternating electric fields to migrate high molecular weight DNA fragments with a high resolution. This method consists of the digestion of bacterial chromosomal DNA with rare-cutting restriction enzymes and in applying an alternating electrical current between spatially distinct pairs of electrodes. DNA molecules migrate at different speeds according to the size of the fragments. Among other things, this technique is considered as the "gold standard" for genotyping, genetic fingerprinting, epidemiological studies, genome size estimation, and studying radiation-induced DNA damage and repair. This chapter describes a PFGE method that can be used to differentiate dairy propionibacteria. PMID:25862063
Sol-gel chromogenic materials and devices
Aegerter, Michel A.
In the last few years the sol-gel process has turned into an interesting and promising method of synthesizing materials for obtaining thin or thick films with definite functions. The techniques of film preparation such as dip and spin coating are simple and allow us to prepare coatings with smooth optical surfaces with controlled stoichiometry, structure and texture. In this paper we give an up to date overview of what has been achieved in the field of chromogenic materials such as anodic or ...
Soluble polymers in sol-gel silica
Beaudry, Christopher Laurent
In the last few years, the inherent versatility of sol-gel processing has led to a significant research effort on inorganic/organic materials. One method of incorporating an organic phase into sol-gel silica is dissolving an organic polymer in a tetraethylorthosilicate (TEOS) solution, followed by in situ polymerization of silica in the presence of organic polymer. The first part of the study involved the development of a two-step (acid-base) synthesis procedure to allow systematic control of acidity in TEOS solutions. With this procedure, it was possible to increase the pH of the TEOS solution while correlating the acidity and properties. The properties were the gelation time, syneresis rate, drying behavior, and xerogel pore structure, as determined by nitrogen sorption. Furthermore, controlling the acidity was shown to control the silica xerogel pore structure. In the second part of the study, the two-step procedure was used to synthesize silica/poly(ethylene glycol) (PEG), and silica/poly(vinyl acetate) (PVAc) composite materials. The content of organic polymer and the molecular weight were varied. The gelation time, the syneresis rate, the drying behavior, and the pore structure were determined for compositions with 10% PEG (M.W. 2,000), 5, 10, and 15% PEG (M.W. 3,400), and 10 and 25% PVAc (M.W. 83,000). Other compositions and molecular weights of PEG lead to sedimentation. In the PEG compositions, the tendency to phase separate was correlated with the effects of the processing variables on the segregation strength and polymerization rate. The PVAc compositions did not show any visible phase separation during processing, giving the composite xerogels an appearance similar to pure silica. The property differences between gels with PEG and gels with PVAc show the relative strength of the interactions with silica. Both polymers exhibit hydrogen bonding between the phases. In the case of PEG, hydrogen bonding between the ether oxygens of the polymer and silanol groups of the hydrolyzed TEOS reduce the gelation time. In the case of PVAc, hydrogen bonding between carbonyl groups of the polymer and silanol groups delay gelation and may physically interfere with condensation. As the competition between the rates of condensation and phase separation are a function of processing conditions, we obtained xerogels that ranged from transparent to opaque.
Characterization of sol-gel-prepared nanoferrites
Shobana, M. K.; Sankar, S.
Spinel Co 1-xMn xFe 2O 4 nanoparticles were prepared by the sol-gel combustion technique. X-ray diffraction (XRD), atomic force microscopy (AFM) and vibration sample magnetometer (VSM) studies have been carried out in order to understand the temperature dependence of their properties. It is observed that the high concentration of Mn 2+ substituted into CoFe 2O 4 tends to reduce the particle size. Furthermore, the influence of Mn on the magnetic and thermal characteristics of Co 1-xMn xFe 2O 4 nanoparticles has been investigated in detail.
Characterization of sol-gel-prepared nanoferrites
International Nuclear Information System (INIS)
Spinel Co1-xMnxFe2O4 nanoparticles were prepared by the sol-gel combustion technique. X-ray diffraction (XRD), atomic force microscopy (AFM) and vibration sample magnetometer (VSM) studies have been carried out in order to understand the temperature dependence of their properties. It is observed that the high concentration of Mn2+ substituted into CoFe2O4 tends to reduce the particle size. Furthermore, the influence of Mn on the magnetic and thermal characteristics of Co1-xMnxFe2O4 nanoparticles has been investigated in detail
Sol-gel processing of ceramics
Schmidt, Helmut K.
The sol-gel process can be considered as an interesting method for the synthesis of tailor-made ceramic raw materials. Two points of view are of special interest: powder synthesis and the processing of ultrafine raw materials. In the case of powder synthesis, high quality and multicomponent powders can be synthesized by control of surface chemistry and agglomerate-free subµm powder can be obtained. The preparation of tailor-made sols offers the possibility of powder-free processing of coatin...
Antimicrobial activity and the mechanism of silver nanoparticle thermosensitive gel
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Chen M
Full Text Available Meiwan Chen1,2,‡, Zhiwen Yang1,‡, Hongmei Wu1, Xin Pan1, Xiaobao Xie3, Chuanbin Wu11Research and Development Center of Pharmaceutical Engineering, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, China; 2State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macau, China; 3Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangzhou, China ‡These authors contributed equally to this workPurpose: The purpose of the present study was to elucidate the antimicrobial activity and mechanism of silver nanoparticles incorporated into thermosensitive gel (S-T-Gel on Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa.Patients and methods: This study investigated the growth, permeability, and morphology of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa cells in order to observe the action of S-T-Gel on the membrane structure of these three bacteria. The cell morphology of normal and treated bacteria cells was assessed by transmission electron microscopy (TEM, and the effects of S-T-Gel on genome DNA of bacterial cells were evaluated by agarose gel electrophoresis.Results: S-T-Gel showed promising activity against Staphylococcus aureus and moderate activity against Escherichia coli and Pseudomonas aeruginosa. The observation with TEM suggested that S-T-Gel may destroy the structure of bacterial cell membranes in order to enter the bacterial cell. S-T-Gel then condensed DNA and combined and coagulated with the cytoplasm of the damaged bacteria, resulting in the leakage of the cytoplasmic component and the eventual death of these three bacteria. In addition, the analysis of agarose gel electrophoresis demonstrated that S-T-Gel could increase the decomposability of genome DNA.Conclusion: These results about promising antimicrobial activity and mechanism of S-T-Gel may be useful for further research and development in in-vivo studies.Keywords: molecule mechanism, bacterial cells, S-T-Gel
Accumulation of humic acid in DET/DGT gels
Veeken, P.L.R., van der; Chakraborty, P.; Van Leeuwen, H.P.
Gel layer based sensors are increasingly employed for dynamic trace metal speciation analysis in aquatic and soil media. In DGT (Diffusive Gradient in Thin film), polyacrylamide hydrogels are commonly used for the diffusive gel layer. While some effects of humic and fulvic acids on the DGT detection of metal species have been observed, the gel permeation properties of the actual humic and fulvic acid compounds themselves have not been analyzed thus far. Here we show with DET (Diffusive Equili...
The Substitute Brain and the Potential of the Gel Model
Pomfret, Roland; Miranpuri, Gurwattan; Sillay, Karl
This purpose of this paper is to review the recent history of the use of agarose gels. Although originally confined to electrophoresis work, agarose gels have proven themselves useful to a number of disciplines in the modern world, which includes brain infusion studies for research involving the treatment of various neurological conditions, such as Parkinson's Disease. In reviewing the relevant research leading up to the modern day, this paper attempts to track agarose gels through their st...
Capillary gel electrophoresis for rapid, high resolution DNA sequencing.
Swerdlow, H; Gesteland, R
Capillary gel electrophoresis has been demonstrated for the separation and detection of DNA sequencing samples. Enzymatic dideoxy nucleotide chain termination was employed, using fluorescently tagged oligonucleotide primers and laser based on-column detection (limit of detection is 6,000 molecules per peak). Capillary gel separations were shown to be three times faster, with better resolution (2.4 x), and higher separation efficiency (5.4 x) than a conventional automated slab gel DNA sequenci...
Smart Polymeric Gels: Redefining the Limits of Biomedical Devices
Chaterji, Somali; Kwon, Il Keun; Park, Kinam
This review describes recent progresses in the development and applications of smart polymeric gels, especially in the context of biomedical devices. The review has been organized into three separate sections: defining the basis of smart properties in polymeric gels; describing representative stimuli to which these gels respond; and illustrating a sample application area, namely, microfluidics. One of the major limitations in the use of hydrogels in stimuli–responsive applications is the di...
Stability of the gel formed during nuclear glass alteration
International Nuclear Information System (INIS)
This thesis is divided in two parts. The first part is dedicated to the study of the protective properties of the gels formed during the alteration of nuclear glass and the second part the stability of these gels after drying and the effect of the sulfate ions are studied. The protective properties of the gel of SON68 glass are assessed at different alteration progress and related to their morphology analyzed by X-ray reflectometry and gas adsorption. Initially a depleted glass layer is obtained, followed by the formation of a gel with an open porosity. Subsequently the gel densifies as the glass alteration rate decreases and finally the pore size increases upon the formation of a dense and thin zone within the film on the glass surface. The increase of the gradient density zone could explain the increase of the protective properties of the gel. A high reaction progress, when the thin and dense zone within the gel is formed, the protective properties are constant. Various simplified glasses are also studied. At high reaction progress there is a dense zone within the gel. The location of this zone depends on the glass composition which control the competition between the species diffusion in solution and their recondensation. The gel morphology, the protective properties, its stability and the glass composition are correlated. The drying induces some modifications of the morphology of the SON68 glass alteration layer (density, thickness and porosity) and of the mechanical properties (cracks, adhesion on glass). For protective gels these modifications are limited and don't raise the protective properties of the gel. The effect of the sulfate ions in a closed system is essentially to complex calcium. For sulfate ions concentrations in geological repository, the stability of the gel is not raised. (author)
Engineering new supramolecular gels: From catalysis to drug delivery
Bachl, Ju?rgen
The present dissertation evaluates the design, characterization and potential applications of functional supramolecular gel-materials. Gels have attracted tremendous scientific interest as they can be obtained from natural sources or derive from readily available building blocks by facile preparation methods. They have conquered our daily life appearing as constituents of commercial products in the fields of biomedicine, agriculture, cosmetics, food thickeners and many more. Gel-materials exh...
Effect of heat on the adsorption properties of silica gel
Christy, Alfred A.
Adsorption properties of silica gel have been attributed to the surface hydroxyl groups of silica gel. Some hydroxyl groups are free standing and called free silanol groups. Some are hydrogen bonded to neighbouring silanol groups. Christy has shown that a high silanol number and a balanced concentration proportionality between these two different types of hydroxyl groups is necessary for effective adsorption of water molecules. Thermal treatment of silica gel samples alters the proportions of...
Gel stabilization in chelate sol-gel preparation of Bi-2223 superconductors.
Czech Academy of Sciences Publication Activity Database
Rubešová, K.; Jakeš, V.; Hlásek, T.; Vašek, Petr; Mat?jka, P.
Ro?. 73, ?. 3 (2012), s. 448-453. ISSN 0022-3697 Institutional research plan: CEZ:AV0Z10100521 Keywords : superconductors * sol-gel growth * infrared spectroscopy * thermogravimetric analysis (TGA) * X-ray diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.527, year: 2012
PCR amplification on microarrays of gel immobilized oligonucleotides
Strizhkov, Boris; Tillib, Sergei; Mikhailovich, Vladimir; Mirzabekov, Andrei
The invention relates two general methods for performing PCR amplification, combined with the detection and analysis of the PCR products on a microchip. In the first method, the amplification occurs both outside and within a plurality of gel pads on a microchip, with at least one oligonucleotide primer immobilized in a gel pad. In the second method, PCR amplification also takes place within gel pads on a microchip, but the pads are surrounded by a hydrophobic liquid such as that which separates the individual gel pads into environments which resemble micro-miniaturized test tubes.
High Impulse Nanoparticulate-Based Gel Propellants Project
National Aeronautics and Space Administration — This proposed Small Business Innovative Research (SBIR) Phase I addresses the development of advanced gel propellants and determination of their suitability for...
Silica scintillating materials prepared by sol-gel methods
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Silica was investigated as a rad-hard alternative to organic polymer hosts for organic scintillators. Silica sol-gels were prepared by hydrolysis of tetramethoxysilane in alcohol solutions. organic dyes were incorporated into the gels by dissolving in methanol at the sol stage of gel formation. The silica sol-gel matrix is very rad-hard. The radiation stability of silica scintillators prepared by this method is dye-limited. Transient radioluminescence was measured following excitation with 30 ps pulses of 20 MeV electrons
Carbopol-Incorporated Thermoreversible Gel for Intranasal Drug Delivery
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Prabagar Balakrishnan
Full Text Available The present study describes the preparation and evaluation of a poloxamer 407 (P407-based thermoreversible gel using Carbopol 934P (C934P as a mucoadhesive polymer and hydroxypropyl-?-cyclodextrin (HP-?-CD for enhancing the aqueous solubility and intranasal absorption of fexofenadine hydrochloride (FXD HCl. The prepared gels were characterized by gelation temperature, viscoelasticity, and drug release profile. Thermoreversibility of P407/C934P gel was demonstrated by rheological studies. The incorporation of carbopol into P407 gel also reduced the amounts of drug released from the gel formulations (p < 0.05. In vivo pharmacokinetic results of the prepared gel formulations in rabbits (at 0.5 mg/kg dose showed that the relative bioavailability of drug from P407/C934P gel was 11.3 and 2.7-fold higher than those of drug solution and P407 gel group, respectively. These findings suggested that developed thermoreversible gels could be used as promising dosage forms to improve intranasal drug absorption.
Carbopol-incorporated thermoreversible gel for intranasal drug delivery.
Balakrishnan, Prabagar; Park, Eun-Kyoung; Song, Chung-Kil; Ko, Hyun-Jeong; Hahn, Tae-Wook; Song, Ki-Won; Cho, Hyun-Jong
The present study describes the preparation and evaluation of a poloxamer 407 (P407)-based thermoreversible gel using Carbopol 934P (C934P) as a mucoadhesive polymer and hydroxypropyl-?-cyclodextrin (HP-?-CD) for enhancing the aqueous solubility and intranasal absorption of fexofenadine hydrochloride (FXD HCl). The prepared gels were characterized by gelation temperature, viscoelasticity, and drug release profile. Thermoreversibility of P407/C934P gel was demonstrated by rheological studies. The incorporation of carbopol into P407 gel also reduced the amounts of drug released from the gel formulations (p < 0.05). In vivo pharmacokinetic results of the prepared gel formulations in rabbits (at 0.5 mg/kg dose) showed that the relative bioavailability of drug from P407/C934P gel was 11.3 and 2.7-fold higher than those of drug solution and P407 gel group, respectively. These findings suggested that developed thermoreversible gels could be used as promising dosage forms to improve intranasal drug absorption. PMID:25749681
Developmental Studies on Metallised UDMH and Kerosene Gels
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T. L. Varghese
Full Text Available The influence of particulate and hydrocolloid gellants and different surfactants on gellation of metallised stable gels of unsymmetrical dimethyl hydrazine (UDMH and kerosene containing 30 per cent 15 micron Aluminium was studied. Metallised UDMH and kerosene gels were characterised with respect to pseudoplasticity, thixotropy, consistency and yield stress using Contrave's rheometer. The effect of shear rate and temperature on the viscosity of these gels was determined. Thermal stability, hypergolicity tests and flow rate studies were also conducted. Metallised UDMH and kerosene gels are found to be stable, thixotropic and pseudoplastic and easily flowing like a liquid under shear force.
Time to first fracture affects sweetness of gels
Sala, G.; Stieger, M.A.
The aim of this study was to investigate the influence of the breakdown behaviour on sweetness intensity of gelled model foods. Emulsion-filled gelatine/agar gels varying mainly in fracture strain (?F) were used. The fracture strain was modified by changing either the ratio between gelatine and agar concentration or the size of the oil droplets embedded in the gel matrix. The sugar content of all gels was kept constant at 6 wt%. The fracture strain of the gels varied between ?F = 37% and ?...
Polyacrylamide gel miniaturization improves protein visualization and autoradiographic detection
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Polyacrylamide gels shrink to one-quarter of their original area when soaked in a 50% (w/v) solution of polyethylene glycol. Gel miniaturization improves the contrast of protein bands, with four valuable consequences. (i) A 5- to 10-fold increase in sensitivity for Coomassie blue is observed. (ii) Gels are more durable; i.e., they resist tearing when wet and they do not crack during drying under vacuum. (iii) Shrunken gels give sharper photographic images and provide better interlane protein band comparisons. (iv) Condensed protein bands lead to an increased sensitivity for detecting low-abundance, radioactively-labeled proteins by fluorography
Effect of bloom strength on radiochromic gel dosimeters
Ebenezer Suman Babu, S.; Ravindran, B. Paul
The Fricke gel dosimeter has been the widely used dosimeter among the gel dosimeters because of its dose response characteristics and easy preparation. The ferrous to ferric conversion that happens in this gel dosimeter on irradiation, corresponds to the absorbed dose of radiation. Gel dosimetry in India is not moving forward because of the import restrictions on the commercially available high bloom strength gelatin (imported 300 bloom). The feasibility of using Fricke gel dosimeter prepared with the locally available gelatin of 240 bloom and 200 bloom were compared with the 300 bloom gelatin taken as standard. The gel samples were prepared with 5% gelatin by weight and irradiated with 60Co gamma radiation for a dose range from 0-3 Gy used clinically. The optical absorption of gel samples were analyzed using spectrophotometer at 585 nm and dose response curves were generated. The results indicate that Fricke gels prepared with 240 bloom have linear dose response and comparable with those prepared with 300 bloom but the use of gels prepared with 200 bloom was found to be limited because of its poor optical transmittance.
Catanionic gels based on cholic acid derivatives.
di Gregorio, M Chiara; Pavel, N Viorel; Miragaya, Javier; Jover, Aida; Meijide, Francisco; Vázquez Tato, José; Tellini, Victor H Soto; Galantini, Luciano
In this paper, the preparation and characterization of an anionic and a cationic surfactant obtained by chemical modifications of a natural bile acid (cholic acid) are reported. The bile acid was modified by introducing a diamine or a dicarboxylic aromatic residue on the lateral chain. The pure cationic surfactant self-assembles in a network of fibers with a cross-section gyration radius of about 15.1 Ĺ, providing hydrogels with a pH-dependent compactness. On the other hand, the anionic molecule gives rise to prolate ellipsoid micelles. Homogeneous catanionic mixtures have also been obtained, with molar fraction of each surfactant ranging from 0.125 to 0.875. At total surfactant concentration of 0.05% (w/v), the mixtures form gels of fibrils partially arranged in secondary twisted superstructures. Comparison of this concentration with the minimum gelation concentration of the pure cationic derivative (0.16% w/v) suggests that, in the mixtures, the presence of the electrostatic component in self-assembly of the molecules allows the formation of gels starting from more dilute samples. In view of these achievements, this work suggests that catanionic mixtures can be exploited to enhance the efficiency of gelators. PMID:24063307
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Dr. Shashikant D. Barhate
Full Text Available High molecular weight water soluble homopolymer of carbapol 934P resins are reported to possess very high viscosity in low concentration, transparency and film forming properties useful for gels. The meloxicam sodium gels were prepared by varying the concentration of penetration enhancer's ethanol, PEG 400, menthol and azone. Selection of optimized batch was done on the basis of results of rheological studies and in-vitro drug permeation. Formulation F19 with highest amount of menthol shows highest permeability of meloxicam sodium (89.96% at the end of 12 hrs this indicates that menthol showed significant permeation enhancement effect. The permeation rate (flux for F19 was 260.11 µg/cm2/h. Obtained R2 values for zero-order model suggests that the drug follows zero-order release kinetics. The rheological characterization of formulated systems showed that the systems exhibit non-Newtonian behavior and The optimized formulation C1 showed higher % cumulative permeation of meloxicam sodium (> 95.00% and permeation rates (flux.
Microfluidic dielectrophoretic sorter using gel vertical electrodes
Luo, Jason; Nelson, Edward L.; Li, G. P.; Bachman, Mark
We report the development and results of a two-step method for sorting cells and small particles in a microfluidic device. This approach uses a single microfluidic channel that has (1) a microfabricated sieve which efficiently focuses particles into a thin stream, followed by (2) a dielectrophoresis (DEP) section consisting of electrodes along the channel walls for efficient continuous sorting based on dielectric properties of the particles. For our demonstration, the device was constructed of polydimethylsiloxane, bonded to a glass surface, and conductive agarose gel electrodes. Gold traces were used to make electrical connections to the conductive gel. The device had several novel features that aided performance of the sorting. These included a sieving structure that performed continuous displacement of particles into a single stream within the microfluidic channel (improving the performance of downstream DEP, and avoiding the need for additional focusing flow inlets), and DEP electrodes that were the full height of the microfluidic walls ("vertical electrodes"), allowing for improved formation and control of electric field gradients in the microfluidic device. The device was used to sort polymer particles and HeLa cells, demonstrating that this unique combination provides improved capability for continuous DEP sorting of particles in a microfluidic device. PMID:24926390
Brownian Dynamics simulations of aging colloidal gels
D'Arjuzon, R J M; Melrose, J R; Arjuzon, Rodolphe J. M. d'; Frith, William; Melrose, John R.
Colloidal gel aging is investigated using very long runs of brownian dynamics simulations. The Asakura Oosawa description of the depletion interaction is used to model a simple colloid polymer mixture. Several regimes are identified during gel formation. The Intermediate scattering function displays a double decay characteristic of systems where some kinetic processes are frozen. The $\\beta$ relaxation at short times is explained in terms of the Krall-Weitz model for the decorelation due to the elastic modes present. The $\\alpha$ relaxation at long times is well described by a stretched exponential, showing a wide spectrum of relaxation times for which the $q$ dependence is $\\tau_{\\alpha} = q^{-2.2}$, lower than for diffusion. For the shortest waiting times, a combination of two stretched exponentials is used, suggesting a bimodal distribution. The extracted relaxation times vary with waiting time as $\\tau_{\\alpha}=\\tau_w^{0.66}$, slower than the simple aging case. The real space displacements are found to be...
Influence of micro gel particles of sodium alginate on gel structure of calcium alginate gels used for controlled release of active substances
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The properties of gel particles of calcium alginate with a chitosan membrane for controlled release of active substances, beside the conformation properties of the macromolecules of sodium alginate and chitosan in solution, depend on the internal structure of the gel which can be controlled or be modified by inducing micro gel structures in the pregel solution with addition of calcium ions. The quantity, dimension and the form of the micro gel structures are in direct relation with the molecular mass, dimension, flexibility, electrical properties, concentration and the mannuronic-to-guluronic ratio from the primary chain of sodium alginate macromolecules as well as temperature. Also, the final properties of controlled release are predetermined from the conditions of gel particle preparation (rate of dropping of sodium alginate solution in the gelling bath, speed of steering of the gelling bath and the time of setting of the gel particles). The research is realised by working with the methods of- gel-permeation chromatography, viscosimetry, static and dynamic light scattering, electric birefringence, spectrophotometry of the kinetics of release of the active substance and scanning electron microscopy.(Author)
Treatment of cutaneous leishmaniasis: cassia fistula fruit gel- intralesional glucantime Vs. placebo gel- intralesional glucantime combination
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Jaffary F
Full Text Available "n Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi;} Background: Cutaneous leishmaniasis is a major health problem in Iran and especially Isfahan province is considered as an endemic area for this disease. Regarding the previous report of positive effects of Cassia fistula boiled extract in the treatment of cutaneous leishmaniasis, this study was designed to evaluate the effect of combination therapy with intralesional meglumine antimoniate and Cassia fistula fruit gel compared to placebo in this disease."n"nMethods: 140 patients with cutaneous leishmaniasis referring to Skin Disease and Leishmaniasis Research Center of Isfahan (SDLRC were randomly allocated in two groups. One group received intralesional meglumine antimoniate injection and Cassia fistula fruit gel and the second group were treated with intralesional meglumine antimoniate and placebo gel. Improvement was defined as complete cure, partial cure and treatment failure. "n"nResults: At 12 week, 47 patients treated with intralesional meglumine antimoniate and topical Cassia fistula fruit gel achieved complete cure (67.1% compared to 29(41.4% patients in placebo treated group. There was significant difference in cure rate between two treatment groups of this study (p<0.001. Nine patients (19% in each group suffered from adverse effects of the treatment such as itching and erythema. There was no significant difference in this regard between two groups (p=0.82. "n"nConclusions: The results of this study shows the efficacy of Cassia fistula fruit gel in increasing the cure rate of cutaneous leishmaniasis lesions achieved by intralesional meglumine antimoniate. Combination therapy of intralesional meglumine antimoniate and Cassia fistula fruit gel could be suggested as a choice for the treatment of acute cutaneous leishmaniasis lesions.
Raman study of lower toxicity polymer gel for radiotherapy dosimetry
Adenan, M. Z.; Ahmad, M.; Mohd Noor, N.; Deyhimihaghighi, N.; Saion, E.
N-isopropyl acrylamide (NIPAM) monomer and N, N' – methylene-bis-acrylamide (BIS) crosslinker were used to synthesize polymer gel dosimeters for a reason that the monomer is lower toxicity which gives a significant advantage over the other polymer gel compositions. The gels were irradiated with Co-60 gamma rays at doses up to 21 Gy and the irradiated NIPAM polymer gels were used to investigate the dose response characteristics based on Raman spectroscopy analysis on the formation of the polymer gels and the consumptions of NIPAM and BIS co-monomers. From the findings, the polymerization was referred to an increment in Raman intensity at 815 cm?1, assigned for C-C stretching mode of NIPAM polymer gel, as the dose increased. The consumptions of the co-monomers were referred to a decrement in Raman intensities at 1025 cm?1 2353 cm?1 for C=C stretching modes of NIPAM and BIS respectively as the dose increased. The increment and decrement in Raman intensities of polymer and co-monomers respectively with increase of dose indicate that there is occurrence of polymerization of NIPAM polymer gels which could be applied in 3D dose distributions for radiotherapy treatment planning. The correlation factor kBIS is greater than kNIPAM showing that the reaction of BIS crosslinker is more efficient than NIPAM monomer to generate 37% of the NIPAM polymer gel.
Yielding of colloidal gels under steady and oscillatory shear
Petekidis, George; Moghimi, Esmaeel; Koumakis, Nick; Forth Team
The structural and rheological properties of intermediate volume fraction colloid polymer gels are examined during and after steady and oscillatory shear flow using rheometry, confocal microscopy, light scattering and Brownian Dynamics simulations. Our main objective is to rationalize the microscopic mechanisms through which one can tune the mechanical properties of such metastable colloidal gels by imposing different types of external shear and flow. Experimentally, the gels consist of model hard sphere particle dispersions of ? = 0.44 with the addition of non-adsorbing linear chains, while BD simulations are conducted for hard spheres with the superposition of an AO potential for depletion attractions. Structural analysis shows that variation of the applied shear rate produces strong changes in the structure of the gels both when under shear and during gel reformation at cessation. Larger rates are characterized by disperse particles and the total breakage of structures at rest, which after cessation evolve with time into strong solids with relatively homogeneous structures. However, smaller rates show large inhomogeneous structures under flow, which do not evolve after cessation and additionally exhibit reduced elasticity and as such are weaker solids. Furthermore oscillatory shear is far more efficient than steady shear creating gels with stronger differences in their elastic modulus. Thus by tuning the way a gel is sheared, one may vary the final strength and structure of the resulting gel. Work in collaboration with R. Besseling, W. C. K. Poon and J. F. Brady
Investigation of silica gel supported inorganic ion exchangers
International Nuclear Information System (INIS)
Microcrystalline zirconium phosphate (?-ZrP), hydrous manganese dioxide (HMnO), ammonium molybdophosphate (AMP), and silica gel supported forms of these materials as well as silica gel (SG) itself were investigated by thermoanalytical, electron microscopic, x-ray diffraction and infrared spectrometric methods. Chemical composition, structure and some related properties of the inorganic ion exchangers mentioned above are reported. (author)
Biocatalysis with Sol-Gel Encapsulated Acid Phosphatase
Kulkarni, Suhasini; Tran, Vu; Ho, Maggie K.-M.; Phan, Chieu; Chin, Elizabeth; Wemmer, Zeke; Sommerhalter, Monika
This experiment was performed in an upper-level undergraduate biochemistry laboratory course. Students learned how to immobilize an enzyme in a sol-gel matrix and how to perform and evaluate enzyme-activity measurements. The enzyme acid phosphatase (APase) from wheat germ was encapsulated in sol-gel beads that were prepared from the precursor…
Optimized conditions for pulsed field gel electrophoretic separations of DNA.
Birren, B. W.; Lai, E.; Clark, S. M.; Hood, L.; Simon, M. I.
Quantitative measurement of DNA migration in gel electrophoresis requires precisely controlled homogeneous electric fields. A new electrophoresis system has allowed us to explore several parameters governing DNA migration during homogeneous field pulsed field gel (PFG) electrophoresis. Migration was measured at different switch times, temperatures, agarose concentrations, and voltage gradients. Conditions which increase DNA velocities permit separation over a wider size range, but reduce reso...
A comparative study of new type polymer gel dosimeters
International Nuclear Information System (INIS)
In this study we have investigated and evaluated some dosimetric properties of polymer gel dosimeter encountered when using gels in clinical radiation therapy environment. Four different compositions of polymer gel dosimeter were manufactured. Two compositions (A and D) represent widely recognized gels prepared following literature instructions. In case of MAGIC type dosimeter (D), gelatin weight fraction was decreased to 5%. During our previous research, we have experienced some substantial changes in behavior when lowering amount of sodium hydroxide and when potassium aluminum sulfate was added. Therefore another two gels were prepared (B and C). Gel dosimeters were evaluated using transversal relaxation rate R2. Details of the used acquisition sequence may be found in Spevacek V. et.al. (2001), only eight echo times were used for R2 calculation in this case. The following properties have been investigated for the four gel compositions: dose response; temperature dependence of dose response; short and long term stability; behavior of gels in a region of steep dose gradient; and uniformity of homogeneously irradiated region. (authors)
Maintenance of Bacterial Cultures on Anhydrous Silica Gel
Lennox, John E.
Suspensions of 20 different cultures were grown on appropriate media, then pipetted into sterile anhydrous silica gel. Silica gel cultures after incubation and refrigerated storage were tested for viability. Results showed little mutation, low replication, low contamination, minimal expenses, and survival up to two years. (CS)
Mechanical similarities observed between polypropylene gels and molten polypropylenes
Oyer, A. J.; Carrillo, J.-M. Y.; Dobrynin, A. V.; Mackintosh, F. C.
The gelation of syndiotactic and isotactic polypropylenes (sPP and iPP) was found when PPs were dissolved in 1,2,3,4-tetrahydronaphthalene (tetralin). Interestingly, it was found that the storage modulus of sPP-gel became higher than that of iPP-gel when PPs were dissolved in tetralin at low PP concentration (40 wt%).
Long-range forces extending from polymer-gel surfaces
Zheng, J; Zheng, Jian-ming; Pollack, Gerald H.
Aqueous suspensions of microspheres were infused around gels of varying composition. The solutes were excluded from zones on the order of 100 micrometers from the gel surface. We present evidence that this finding is not an artifact, and that solute-repulsion forces exist at distances far greater than conventional theory predicts. The observations imply that solutes may interact over an unexpectedly long range.
Development of Satranidazole Mucoadhesive Gel for the Treatment of Periodontitis
Bansal, K; Rawat, M. K.; Jain, A.; Rajput, A.; Chaturvedi, T.P.; Singh, S
The aim of the paper was to develop satranidazole-containing mucoadhesive gel for the treatment of periodontitis. Different mucoadhesive gels were prepared, using various gelling agents like sodium carboxymethylcellulose (SCMC), poloxamer 407, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, and the mucoadhesive polymer carbopol 934P. The selected formulations (based on the mucoadhesive force) were studied for different mechanical properties, such as mucoadhesive s...
Multiresponsive reversible gels based on charge-driven assembly
Lemmers, Marc; Sprakel, Joris; Voets, Ilja K.; Gucht, Jasper van der; Stuart, Martien A Cohen
Coassembly of an ABA triblock copolymer with charged end blocks and an oppositely charged polyelectrolyte yields gels that respond to changes in concentration, temperature, ionic strength, pH value, and charge composition. Above the critical gel concentration, the triblock copolymers bridge micelles, forming a sample-spanning transient network of interconnected micelles.
Dose response characteristics in polymer gel for the composition ratio
International Nuclear Information System (INIS)
Although a gel dosimeter is not widely used, it has many potential merits for 3D dosimetry in the development of radiotherapy techniques. Because conventional gel dosimeters tend to sensitively polymerize with oxygen. A new polymer gel that solves these problems was introduced recently. The gel dosimeter contains anti-oxidants that eliminate oxygen chemically instead of using complicated facilities. The type and the concentration of the monomer affect the polymerization of the polymer gel dosimeter. Therefore, the polymerization of the normoxic polymer gel dosimeter is affected by anti-oxidant, the monomer, the constituent ratio, and the condition of the monomer, so many researchers have concentrated on the anti-oxidant, the type of monomer, and the constituent ratio. In this study, a normoxic polymer gel dosimeter was composed using anti-oxidants in a laboratory, and the dose response and sensitivity were measured. The results of this study are as follow the threshold R2 values were reduced, and the radio sensitivity was reduced with the increasing MAA ratio. Otherwise, the increase in the gelatin represented an increase and decrease in the threshold value of R2 values and the radio sensitivity, respectively. Therefore, in this study, 6 - 8 % MAA ratios and an 8 % gelatin ratio, considering the aging effect of the gel, were the optimal values.
Impedance and polarisation studies of new lithium polyelectrolyte gels
Krok, F.; Dygas, J. R.; Misztal-Faraj, B.; Florja?czyk, Z.; Bzducha, W.
Electrical conductivity, interaction with lithium metal and apparent Li + transference number of gel polyelectrolytes was examined by the impedance spectroscopy and the dc polarisation of cells. Gel polyelectrolytes were obtained by crosslinking of plasticized lithium salts derived from comb-like half ester of maleic acid copolymer. Two gels contained additives: either BF 3 as an agent complexing carboxylic anions or LiN(CF 3SO 2) 2 salt as a source of additional lithium ions. The measured impedance spectra of cells Li/gel/Li were simulated by an equivalent circuit. The time evolution of the circuit parameters indicated growth of passivation layer and degradation of the electrolyte. In all studied gels, the apparent Li + transference number had low values, which decreased upon time of storage of cells with lithium electrodes. Probably small ions are formed upon chemical interaction between lithium and dimethoxyethylenesulfoxide—the polar solvent used as a plasticizer.
Formaldehyde increases MAGIC gel dosimeter melting point and sensitivity
International Nuclear Information System (INIS)
Polymeric gel dosimeters are being used to verify three-dimensional (3D) dose distributions of different types of radiotherapy treatments, especially the most complexes ones. An important factor that can limit the wider use of this kind of dosimeter is temperature, as gel melting can destroy 3D information. This work shows that the addition of formaldehyde to the gel preparation increases the melting point, allowing its use in warmer environments, including up to body temperature. An addition of 3% in mass of the formaldehyde solution to a MAGIC type gel dosimeter increased its melting point from 25 to 69 deg. C. Also important were a 10.5% increase in gel sensitivity and an expressive decrease in relaxation rate R2 uncertainty that added to the agreement of the depth dose distribution measurement with the expected dosimetric data of the LINAC show the potential applicability of this new dosimeter for 3D dose verification.
Molecular Gels Materials with Self-Assembled Fibrillar Networks
Weiss, Richard G
Molecular gels and fibrillar networks – a comprehensive guide to experiment and theory Molecular Gels: Materials with Self-Assembled Fibrillar Networks provides a comprehensive treatise on gelators, especially low molecular-mass gelators (LMOGs), and the properties of their gels. The structures and modes of formation of the self-assembled fibrillar networks (SAFINs) that immobilize the liquid components of the gels are discussed experimentally and theoretically. The spectroscopic, rheological, and structural features of the different classes of LMOGs are also presented. Many examples of the application of the principal analytical techniques for investigation of molecular gels (including SANS, SAXS, WAXS, UV-vis absorption, fluorescence and CD spectroscopies, scanning electron, transmission electron and optical microscopies, and molecular modeling) are presented didactically and in-depth, as are several of the theories of the stages of aggregation of individual LMOG molecules leading to SAFINs. Several actua...
Processing and characterization of Aloe vera gel for hydrogel preparation
International Nuclear Information System (INIS)
This work describes the processing and characterization of Aloe vera gel for the preparation of hydrogels through gamma radiation from polymers and natural products in order to be used in biomedical applications. Processing was carried out immersing slices of aloe in distilled water for phenolic compound extraction. Through UV-VIS spectroscopy, 48 hours was determined as the optimal soaking time, at which organoleptic characteristics of the gel as well as its pH were acceptable. An increase of pH was observed on the gel that was stored at room temperature. The non processed gel showed a pink coloration. Results of gel yield values were not high. Microbiological tests showed a high bioburden. (author)
Nonlinear Elasticity and Cavitation of a Triblock Copolymer Gel
Kundu, Santanu; Hashemnejad, Seyed Meysam; Zabet, Mahla; Mishra, Satish
Polymer gels are subjected to large-strain deformation during their applications. The gel deformation at large-strain is non-linear and can often lead to failure of the material. Here, we report the large-strain deformation behavior of a physically cross-linked, swollen polymer gel, which displays unique strain-stiffening response at large-strain. Investigations were performed using large amplitude oscillatory shear (LAOS) and custom developed cavitation rheology techniques. Gent constitutive model, which considers finite extensibility of midblock, was fitted with the LAOS data, therefore, linking the estimated parameters from LAOS analysis to the structure of the gel. Cavitation experiments were conducted as a function of temperature. Both analytical method and finite-element based modeling have been implemented to capture the pressure response in cavitation experiments. Our results provide a critical understanding of gel failure mechanism at large-strain.
Opportunities for sol-gel materials in fuel cells
International Nuclear Information System (INIS)
Fuel cells are electrochemical devices that convert the chemical energy of a fuel and oxidant directly to electrical energy. Three types of fuel cells are (a) proton-exchange membrane fuel cells (PEMFC), (b) molten carbonate fuel cells (MCFC) and (c) solid oxide fuel cells (SOFC). In each case, there is a role for sol-gel processing. In the case of PEMFC, sol-gel modifications to the membrane are designed to increase the operating temperature. In the case of MCFC, sol-gel corrosion barriers extend the lifetime of the current collector. Finally, sol-gel processing is being used to assemble the electrolyte and electrode layers in SOFC and related oxygen generating devices. Examples are given for the application of sol-gel processing in each system, pointing out the derived benefits and areas for further development. (author)
Use of chitosan gel for the purification of protein
Scientific Electronic Library Online (English)
ZhenXing, Tang; JunQing, Qian.
Full Text Available The aim of this study was to optimize the preparation of chitosan gel and to use it for protein purification. The optimized preparation parameters were chitosan concentration 2.0%, glutaraldehyde concentration 0.6%, low cross-linking rate, NaOH concentration 1.6%, amount of NaBH4 0.4 g. In order to [...] use the chitosan gel, the elution conditions were optimized as follows. NaCl concentration 0.05 mol/L in the tris-HCl (pH 9.05) at the flow rate of 2.03.0 mL/min. Particle size of chitosan gel was 120-140 µm. Neutral protease could be separated into four ingredients through chitosan gel column. The yield of enzyme was more than 90%. Albumin bovine serum could be separated into two ingredients through gel column and the total yield of albumin bovine serum was more than 70%.
Use of chitosan gel for the purification of protein
Directory of Open Access Journals (Sweden)
ZhenXing Tang
Full Text Available The aim of this study was to optimize the preparation of chitosan gel and to use it for protein purification. The optimized preparation parameters were chitosan concentration 2.0%, glutaraldehyde concentration 0.6%, low cross-linking rate, NaOH concentration 1.6%, amount of NaBH4 0.4 g. In order to use the chitosan gel, the elution conditions were optimized as follows. NaCl concentration 0.05 mol/L in the tris-HCl (pH 9.05 at the flow rate of 2.03.0 mL/min. Particle size of chitosan gel was 120-140 µm. Neutral protease could be separated into four ingredients through chitosan gel column. The yield of enzyme was more than 90%. Albumin bovine serum could be separated into two ingredients through gel column and the total yield of albumin bovine serum was more than 70%.
Laser CT evaluation on normoxic PAGAT gel dosimeter
Kumar, D. S.; Samuel, E. J. J.; Watanabe, Y.
Optical computed tomography has been shown to be a potentially useful imaging tool for the radiation therapy physicists. In radiation therapy, researchers have used optical CT for the readout of 3D dosimeters. The purpose of this paper is to describe the initial evaluation of a newly fabricated laser CT scanner for 3D gel dosimetry which works using the first generation principle. A normoxic PAGAT (Polyacrylamide Gelatin and Tetrakis) gel is used as a dosimeter for this analysis. When a laser passes through the gel phantom, absorption and scattering of photon take place. The optical attenuation coefficient of the laser can be obtained by measuring its intensity after passing through the gel by a sensor. The scanner motion is controlled by a computer program written in Microsoft Visual C++. Reconstruction and data analysis on the irradiated gel phantom is performed by suitable algorithm using Matlab software.
PC based automated sol-gel pilot plant
International Nuclear Information System (INIS)
Sol-gel process offers an easy wet chemical route for preparation of fuel elements in the form of microspheres of desired size. The system is designed for preparation of dry gel particles of uranium oxide and uranium-plutonium oxide. Processes involved are pre mixing, feed dispersion, gel formation, washing and drying of gel particles. The sol-gel assembly with a production capacity of ?3 kg/day is housed in an eight module glove box. To execute different process sequences a PC based system has been developed. PC is the main system controller. Control of process involves control of liquid flow, solenoid valves, pneumatic valves, pumps, level control sequence, time based sequence, conductivity based sequence etc. Peripheral instruments associated with PC are level controllers, pressure indicator unit, power oscillator, conductivity meter, silicon oil heating unit and belt drying unit. (author). 4 refs., 1 fig
Volume phase transitions of cholesteric liquid crystalline gels
Matsuyama, Akihiko
We present a mean field theory to describe anisotropic deformations of a cholesteric elastomer without solvent molecules and a cholesteric liquid crystalline gel immersed in isotropic solvents at a thermal equilibrium state. Based on the neoclassical rubber theory of nematic elastomers, we derive an elastic energy and a twist distortion energy, which are important to determine the shape of a cholesteric elastomer (or gel). We demonstrate that when the elastic energy dominates in the free energy, the cholesteric elastomer causes a spontaneous compression in the pitch axis and elongates along the director on the plane perpendicular to the pitch axis. Our theory can qualitatively describe the experimental results of a cholesteric elastomer. We also predict the first-order volume phase transitions and anisotropic deformations of a gel at the cholesteric-isotropic phase transition temperature. Depending on a chirality of a gel, we find a prolate or oblate shape of cholesteric gels.
Development of naftifine hydrochloride alcohol-free niosome gel.
Barakat, Heba S; Darwish, Inas A; El-Khordagui, Labiba K; Khalafallah, Nawal M
Marketed topical gels of the antifungal drug naftifine hydrochloride contain 50% alcohol as cosolvent. Repeated exposure to alcohol could be detrimental to skin. The aim of this study is to develop an alcohol-free niosome gel containing 1% naftifine hydrochloride. Niosomes were prepared and formulation variables were optimized to achieve maximum entrapment coupled with stability. Maximum drug entrapment and niosome stability entailed imparting a negative charge to the vesicles where entrapment efficiency reached 50%. Niosomes were incorporated into a hydroxyethylcellulose gel. The final gel contained a total drug concentration of 1% (wt/wt) half of which was entrapped in the niosomes. The results suggest the potential usefulness of the niosome gel. PMID:18989805
Sonochemical preparation of SbSI gel.
Nowak, M; Szperlich, P; Bober, L; Szala, J; Moskal, G; Stróz, D
A novel sonochemical method for direct preparation of nanocrystalline antimony sulfoiodide (SbSI) has been established. The SbSI gel was synthesized using elemental Sb, S and I in the presence of ethanol under ultrasonic irradiation (35 kHz, 2 W/cm2) at 50 degrees C for 2 h. The products were characterized by using techniques such as powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and optical diffuse reflection spectroscopy (DRS). The SEM and HRTEM investigations exhibit that the as-prepared samples are made up of large quantity nanowires with diameters of about 10-50 nm and lengths reaching up to several micrometers and single-crystalline in nature. PMID:17964844
Photothermally reprogrammable buckling of nanocomposite gel sheets.
Hauser, Adam W; Evans, Arthur A; Na, Jun-Hee; Hayward, Ryan C
Patterning deformation within the plane of thin elastic sheets represents a powerful tool for the definition of complex and stimuli-responsive 3D buckled shapes. Previous experimental methods, however, have focused on sheets that access a limited number of shapes pre-programmed into the sheet, restricting the degree of dynamic control. Here, we demonstrate on-demand reconfigurable buckling of poly(N-isopropylacrylamide-co-acrylic acid) (PNIPAM) hydrogel network films containing gold nanoparticles (AuNPs) by patterned photothermal deswelling. Predictable, easily controllable, and reversible transformations from a single flat gel sheet to numerous different three-dimensional forms are shown. Importantly, the response time is limited by poroelastic mass transport, rather than photochemical switching kinetics, enabling reconfiguration of shape on timescales of several seconds, with further increases in speed possible by reducing film thickness. PMID:25752941
Sol-gel coatings for optoelectronic devices
Avellaneda, Cesar O.; Macedo, Marcelo A.; Florentino, Aariovaldo O.; Aegerter, Michel A.
Nb2O5 prepared by a sol-gel process in form of coatings and aerogels are new materials which present interesting properties: (a) the coatings present electrochromic properties and exhibit a blue coloration under Li+ insertion with 100% reversible variation of the optical transmission in the visible and near infrared range between 80% and 20% and have a high chemical stability (tested up to 2000 cycles), (b) they are semiconductor and present a photoelectric effect when illuminating in the UV region ((lambda) < 360 nm). These films are therefore very promising to be used in electrochromic devices, as electrodes for photoelectrochemical purpose and the development of nanocrystalline solar cell, and (c) when prepared in aerogel form, the high BET surface area of the powders is a promising asset to use these new materials for catalytic purposes.
Modelling of erosion of bentonite gel by gel/sol flow
International Nuclear Information System (INIS)
Bentonite intrusion into a fracture intersecting the canister deposition hole is modelled. The model describes the expansion of the bentonite within the fracture. It accounts for the repulsive electrostatic double-layer forces, the attractive van der Waals forces and friction forces between the particles and the water. The model also takes into account the diffusion of the colloid particles in the smectite sol. Diffusion of a counterion, sodium, is accounted for as this strongly influences the double layer force and the viscosity of the gel/sol. The gel/sol is considered to be a fluid with a varying viscosity that is strongly dependent on the bentonite volume fraction in the gel and the sodium concentration in the water. Two different geometries were modelled; a rectangular and a cylindrical. The rectangular geometry was used to gain experience with the processes and mechanisms and how they interact since the cylindrical geometry was somewhat less stable numerically and more time consuming. In the rectangular geometry a fracture 1 metre long in the flow direction was modelled. In both geometries the fracture size was selected sufficiently large to ensure that the water velocity, near the distant border was nearly the same as the approaching water velocity and that the smectite concentration there was vanishingly small. It was found that the velocity of the fluid drops considerably where the bentonite volume fraction is larger than 1-2%. This is due to the strong increase in viscosity with increasing bentonite volume fraction. The loss of smectite by the slowly flowing fluid was found to be proportional to the square root of the seeping water velocity for the rectangular geometry. For the cylindrical geometry, the dependence is somewhat lower (exponent about 0.4) since the length of the gel/water interface decreases with increasing water flow rate. The penetration depth of the gel/water interface decreases with increasing water flow rate. For water velocity of the order of a metre per year the gel may penetrate several metres into the fracture when steady state is reached. The simulations were made with only sodium as counterion. Most simulations had sodium concentrations below the critical coagulation concentration, CCC. In the compacted bentonite at the fracture mouth it was 10 mM and 0.1 mM in the approaching water. At these concentrations the gel is expansive and can turn into a sol releasing colloidal particles. The low ion concentration has a strong impact on the fluid viscosity, which increases with decreasing ionic strength. At the same time, however the repulsion forces between the smectite particles increase causing a quicker expansion. Simulations with higher sodium concentrations had a marginal influence on the erosion rate. For the highest water flow rates the smectite loss could be up to 0.3 kg per year for one canister. This is more than one order of magnitude larger than what could be reached by smectite particle diffusion alone if fluid flow was neglected. In experiments in downward facing slits (fractures) it has been found that bentonite releases gel agglomerates much faster than expected. These are released and sediment also under conditions where it is expected that the smectite particles should have separated into individual smectite sheets, which would not noticeably be influenced by gravity. The reasons for this behaviour are not understood. In the modelling it is assumed that there are no other larger non-smectite particles that would be left behind to gradually build up a bed of particles that could act as filter, slowing down or even straining further smectite penetration into the fracture. The modelling results could therefore be highly pessimistic because bentonites contain tens of percent of accessory minerals that do not form colloids and the presence of which may cause the expansion to be slowed down by friction against the fracture walls
Modelling of erosion of bentonite gel by gel/sol flow
Energy Technology Data Exchange (ETDEWEB)
Moreno, Luis; Neretnieks, Ivars; Longcheng Liu (Chemical Engineering and Technology, School of Chemical Science and Engineering, Royal Institute of Technology, Stockholm (Sweden))
Bentonite intrusion into a fracture intersecting the canister deposition hole is modelled. The model describes the expansion of the bentonite within the fracture. It accounts for the repulsive electrostatic double-layer forces, the attractive van der Waals forces and friction forces between the particles and the water. The model also takes into account the diffusion of the colloid particles in the smectite sol. Diffusion of a counterion, sodium, is accounted for as this strongly influences the double layer force and the viscosity of the gel/sol. The gel/sol is considered to be a fluid with a varying viscosity that is strongly dependent on the bentonite volume fraction in the gel and the sodium concentration in the water. Two different geometries were modelled; a rectangular and a cylindrical. The rectangular geometry was used to gain experience with the processes and mechanisms and how they interact since the cylindrical geometry was somewhat less stable numerically and more time consuming. In the rectangular geometry a fracture 1 metre long in the flow direction was modelled. In both geometries the fracture size was selected sufficiently large to ensure that the water velocity, near the distant border was nearly the same as the approaching water velocity and that the smectite concentration there was vanishingly small. It was found that the velocity of the fluid drops considerably where the bentonite volume fraction is larger than 1-2%. This is due to the strong increase in viscosity with increasing bentonite volume fraction. The loss of smectite by the slowly flowing fluid was found to be proportional to the square root of the seeping water velocity for the rectangular geometry. For the cylindrical geometry, the dependence is somewhat lower (exponent about 0.4) since the length of the gel/water interface decreases with increasing water flow rate. The penetration depth of the gel/water interface decreases with increasing water flow rate. For water velocity of the order of a metre per year the gel may penetrate several metres into the fracture when steady state is reached. The simulations were made with only sodium as counterion. Most simulations had sodium concentrations below the critical coagulation concentration, CCC. In the compacted bentonite at the fracture mouth it was 10 mM and 0.1 mM in the approaching water. At these concentrations the gel is expansive and can turn into a sol releasing colloidal particles. The low ion concentration has a strong impact on the fluid viscosity, which increases with decreasing ionic strength. At the same time, however the repulsion forces between the smectite particles increase causing a quicker expansion. Simulations with higher sodium concentrations had a marginal influence on the erosion rate. For the highest water flow rates the smectite loss could be up to 0.3 kg per year for one canister. This is more than one order of magnitude larger than what could be reached by smectite particle diffusion alone if fluid flow was neglected. In experiments in downward facing slits (fractures) it has been found that bentonite releases gel agglomerates much faster than expected. These are released and sediment also under conditions where it is expected that the smectite particles should have separated into individual smectite sheets, which would not noticeably be influenced by gravity. The reasons for this behaviour are not understood. In the modelling it is assumed that there are no other larger non-smectite particles that would be left behind to gradually build up a bed of particles that could act as filter, slowing down or even straining further smectite penetration into the fracture. The modelling results could therefore be highly pessimistic because bentonites contain tens of percent of accessory minerals that do not form colloids and the presence of which may cause the expansion to be slowed down by friction against the fracture walls
Clotrimazole nanoparticle gel for mucosal administration
International Nuclear Information System (INIS)
In this study a formulation suitable to be applied on oral and/or vaginal mucosa has been developed for the treatment of fungal infections. The aim of the research is a comparison between clotrimazole (CLO) containing semisolid formulations based on monoolein aqueous dispersion (MAD) or nanostructured lipid carrier (NLC). MAD and NLC have been characterized in terms of morphology and dimensional distribution by cryogenic Transmission Electron Microscopy (cryo-TEM) and Photon Correlation Spectroscopy (PCS). CLO was encapsulated with high entrapment efficiency both in MAD and in NLC, according to Sedimentation Field Flow Fractionation (SdFFF) combined with HPLC. CLO recovery in MAD and NLC has been investigated by time. In order to obtain formulations with suitable viscosity for mucosal application, MAD was diluted with a carbomer gel, while NLC was directly viscosized by the addition of poloxamer 407 in the dispersion. The rheological properties of MAD and NLC after viscosizing have been investigated. Franz cell has been employed to study CLO diffusion from the different vehicles, evidencing diffusion rates from MAD and NLC superimposable to that obtained using Canesten®. An anticandidal activity study demonstrated that both CLO-MAD and CLO-NLC were more active against Candida albicans with respect to the pure drug. Highlights: ? Comparison between monoolein aqueous dispersion (MAD) and nanostructured lipid carrier (NLC). ? Clotrimazole (CLO) encapsulatNLC). ? Clotrimazole (CLO) encapsulated with high entrapment efficiency both in MAD and in NLC. ? The solid matrix of NLC controls CLO degradation better than MAD. ? CLO containing MAD and NLC exhibits a higher anticandidal activity than the free drug. ? Simple production of CLO-NLC based poloxamer gel, suitable for industry scaling up
Phyllosilicates and Amorphous Gel in the Nakhlites
Hicks, L. J.; Bridges, J. C.; Gurman, S. J.
Previous studies of the nakhlite martian meteorites have revealed hydrothermal minerals present within the fractures of the olivine minerals and the mesostasis. The olivine fractures of the Lafayette nakhlite reveal variations with initial deposits of siderite on the fracture walls, followed by crystalline phyllosilicates (smectite), and finishing with a rapidly cooled amorphous silicate gel within the central regions of the fractures. The mesostasis fractures of Lafayette also contain a crystalline phyllosilicate (serpentine). The amorphous gel is the most abundant secondary phase within the fractures of the other nakhlites [1, 2]. By studying nine nakhlite samples, including Lafayette, Governador Valadares, Nakhla, Y-000593, Y-000749, Miller-Range 03346, NWA 817, NWA 998, and NWA 5790, our aim is to constrain the identity of the phyllosilicate secondary phase minerals found throughout the nakhlite martian meteorites. This is achieved using methods including Electron Probe Micro-analysis (EPMA); X-ray Absorption Near-Edge Structure (Fe-K XANES) spectroscopy measured using Beamline I-18 at the Diamond Light Source synchrotron; and the use of Transmission Electron Microscopy (TEM) at the University of Leicester for High-Resolution (HR) imaging and Selected Area Electron Diffraction (SAED). BF studying nine nakhlite samples, including Lafayette, Governador Valadares, Nakhla, Y-000593, Y-000749, Miller-Range 03346, NWA 817, NWA 998, and NWA 5790, our aim is to constrain the identity of the phyllosilicate secondary phase minerals found throughout the nakhlite martian meteorites. This is achieved using methods including Electron Probe Micro-analysis (EPMA); X-ray Absorption Near-Edge Structure (Fe-K XANES) spectroscopy measured using Beamline I-18 at the Diamond Light Source synchrotron; and the use of Transmission Electron Microscopy (TEM) at the University of Leicester for High-Resolution (HR) imaging and Selected Area Electron Diffraction (SAED).
Clotrimazole nanoparticle gel for mucosal administration
Energy Technology Data Exchange (ETDEWEB)
Esposito, Elisabetta, E-mail: firstname.lastname@example.com [Department of Pharmaceutical Sciences, University of Ferrara, I-44121 Ferrara (Italy); Ravani, Laura [Department of Pharmaceutical Sciences, University of Ferrara, I-44121 Ferrara (Italy); Contado, Catia [Department of Chemistry, University of Ferrara, Ferrara (Italy); Costenaro, Andrea [Department of Pharmaceutical Sciences, University of Ferrara, I-44121 Ferrara (Italy); Drechsler, Markus [Macromolecular Chemistry II, University of Bayreuth (Germany); Rossi, Damiano [Department of Biology and Evolution, LT Terra and Acqua Tech UR7, University of Ferrara, Ferrara (Italy); Menegatti, Enea [Department of Pharmaceutical Sciences, University of Ferrara, I-44121 Ferrara (Italy); Grandini, Alessandro [Department of Biology and Evolution, LT Terra and Acqua Tech UR7, University of Ferrara, Ferrara (Italy); Cortesi, Rita [Department of Pharmaceutical Sciences, University of Ferrara, I-44121 Ferrara (Italy)
In this study a formulation suitable to be applied on oral and/or vaginal mucosa has been developed for the treatment of fungal infections. The aim of the research is a comparison between clotrimazole (CLO) containing semisolid formulations based on monoolein aqueous dispersion (MAD) or nanostructured lipid carrier (NLC). MAD and NLC have been characterized in terms of morphology and dimensional distribution by cryogenic Transmission Electron Microscopy (cryo-TEM) and Photon Correlation Spectroscopy (PCS). CLO was encapsulated with high entrapment efficiency both in MAD and in NLC, according to Sedimentation Field Flow Fractionation (SdFFF) combined with HPLC. CLO recovery in MAD and NLC has been investigated by time. In order to obtain formulations with suitable viscosity for mucosal application, MAD was diluted with a carbomer gel, while NLC was directly viscosized by the addition of poloxamer 407 in the dispersion. The rheological properties of MAD and NLC after viscosizing have been investigated. Franz cell has been employed to study CLO diffusion from the different vehicles, evidencing diffusion rates from MAD and NLC superimposable to that obtained using Canesten{sup Registered-Sign }. An anticandidal activity study demonstrated that both CLO-MAD and CLO-NLC were more active against Candida albicans with respect to the pure drug. Highlights: Black-Right-Pointing-Pointer Comparison between monoolein aqueous dispersion (MAD) and nanostructured lipid carrier (NLC). Black-Right-Pointing-Pointer Clotrimazole (CLO) encapsulated with high entrapment efficiency both in MAD and in NLC. Black-Right-Pointing-Pointer The solid matrix of NLC controls CLO degradation better than MAD. Black-Right-Pointing-Pointer CLO containing MAD and NLC exhibits a higher anticandidal activity than the free drug. Black-Right-Pointing-Pointer Simple production of CLO-NLC based poloxamer gel, suitable for industry scaling up.
One step antiglare sol-gel coating for screens by sol-gel techniques
Schelle, Christian; Mennig, Martin; Krug, Herbert; Jonschker, Gerhard; Schmidt, Helmut K.
Anti-reflection coatings on glass substrates were prepared by the application of sol-gel coatings of silica containing crystalline tin oxide particles. The sol was coated on commercially available float glass by dip-coating and spin-coating techniques. Increasing the surface roughness of the float glass (factor of 50) by a particulate coating material resulted in anti-reflection effects comparable to frosted glass. Haze and clarity, which are a measure for the contrast and definition of an op...
Diffusion of Rose Bengal in agar gel: variation with the concentration of the diffusant and the gel
International Nuclear Information System (INIS)
The diffusion of Rose Bengal 131I in agar gel is studied in the concentration range of 10-7 to 10-5M. In addition, effects due to varying the concentration of the gel and temperature are reported. (author)
Performance of external microwave applicators measured in Guy gel and agar-saline gel
International Nuclear Information System (INIS)
Before any predictions can be made about temperature patterns from an external microwave applicator, it is necessary to know the specific absorption rate (SAR) distribution of the applicator in a medium. To do this, a sufficient forward power of 915 MHz microwaves was delivered and the temperature rise in the medium at various depths was recorded for the first 40 seconds after the power was turned on. This was repeated at 1 cm intervals along the two perpendicular axes of the applicator. SAR distributions of several commercially available applicators were compared in a muscle equivalent Guy gel and an agar-saline gel. Applicators with the same aperture size may have different SAR distributions due to different construction design. The SAR distribution measured in the two media did not differ significantly, suggesting that the agar gel may have some utility in characterizing microwave applicators. In addition, the agar-saline phantom can be used in a steady state phantom for the measurement of temperature distribution patterns. The steady state method allows a rapid and detailed field mapping of the microwave applicator
The effect of residual water on antacid properties of sucralfate gel dried by microwaves
Gainotti, Alessandro; Losi, Elena; Colombo, Paolo; Santi, Patrizia; Sonvico, Fabio; Baroni, Daniela; Massimo, Gina; Colombo, Gaia; Del Gaudio, Pasquale
The aim of this work was to study the acid neutralization characteristics of microwave-dried sucralfate gel in relation to the water content and physical structure of the substance. Several dried sucralfate gels were compared with humid sucralfate gel and sucralfate nongel powder in terms of neutralization rate and buffering capacity. Humid sucralfate gel and microwave-dried gel exhibited antacid effectiveness. In particular, the neutralization rate of dried gel powders was inversely related ...
Physical properties of nanoparticle silica gel doped with CdS prepared by sol-gel technique
Battisha, I. K.
CdS/silica xerogel glasses were prepared via silica gels containing mixture solution of 0.2 M (CdCl2 and thiourea) with molar ratio 1:1. Doping the gels with this mixture solution and its heat treatment gave transparent yellow silica-gel glasses doped with CdS crystals. X-ray diffraction and transmission electron microscope make it possible to evaluate the nanoparticle size of the prepared samples. The nanoparticle size was dependent on the concentration of the dopant materials and the heating temperature. In the optical transmission spectra, the absorption edge exhibited a blue shift compared to that of the bulk CdS, and its energy shift was reciprocally proportional to the square of the radius. Thus the quantum-size effect could be found for the silica gel containing CdS prepared by the sol-gel process. The energy band gap shifted to higher energy for smaller nanoparticle size.
Açúcar granulado ou em gel no tratamento de feridas em căes / Granulated sugar and sugar gel in treating canine wounds
Scientific Electronic Library Online (English)
Gabriele Maria Callegaro, Serafini; Joăo Eduardo Wallau, Schossler; Anne Santos do, Amaral; Luciana Hermes, Dutra; Angela Piantá, Dibi; Priscila, Drogemoller; Cristiane de Lima, Athayde.
Full Text Available O açúcar é um dos produtos mais utilizados para tratamento de feridas em medicina veterinária. Sua principal vantagem é o efeito higroscópico nos tecidos e morte das bactérias por plasmólise, tornando-o um bactericida pelo efeito físico realizado, sem levar ŕ resistęncia bacteriana. O objetivo deste [...] experimento foi comparar a evoluçăo cicatricial de feridas cutâneas com o uso tópico de açúcar na forma granulada e na forma de gel. Foram tratadas 16 feridas de căes, das quais oito receberam tratamento com açúcar granulado (grupo A) e oito com gel de açúcar (grupo G). O tempo de tratamento, independente do grupo, levou, no mínimo, sete dias e, no máximo, 14. Quanto ŕ aplicabilidade, o gel demonstrou melhor adesăo nas feridas e preenchimento do produto no subcutâneo de forma mais efetiva que o açúcar granulado. Conclui-se que tanto o gel quanto o açúcar foram efetivos na cicatrizaçăo das feridas dos animais deste experimento, sendo que o gel demonstrou precocidade na retraçăo cicatricial nos primeiros sete dias. Abstract in english Sugar is one of the most widely used products in the treatment of wounds in veterinary medicine. Its main advantage is the hygroscopic effect on tissues and the bacterial death by plasmolysis, making it a bactericidal agent due to the physical effect observed, without leading to bacterial resistance [...] . The aim of this experiment was to compare cicatricial evolution of cutaneous wounds with the topical use of sugar either granulated or as gel. Sixteen canine wounds were treated: eight with granulated sugar (group A) and eight with sugar gel (group G). Treatment time, independent of the group, took at least seven days and a maximum of 14. Concerning applicability, gel sugar showed better adhesion to wounds and subcutaneous filling more effectively that granulated sugar. It is concluded that both granulated and gel sugar were effective in healing skin wounds, the gel being precocious in cicatricial retraction within the first seven days of treatment.
Açúcar granulado ou em gel no tratamento de feridas em căes Granulated sugar and sugar gel in treating canine wounds
Directory of Open Access Journals (Sweden)
Gabriele Maria Callegaro Serafini
Full Text Available O açúcar é um dos produtos mais utilizados para tratamento de feridas em medicina veterinária. Sua principal vantagem é o efeito higroscópico nos tecidos e morte das bactérias por plasmólise, tornando-o um bactericida pelo efeito físico realizado, sem levar ŕ resistęncia bacteriana. O objetivo deste experimento foi comparar a evoluçăo cicatricial de feridas cutâneas com o uso tópico de açúcar na forma granulada e na forma de gel. Foram tratadas 16 feridas de căes, das quais oito receberam tratamento com açúcar granulado (grupo A e oito com gel de açúcar (grupo G. O tempo de tratamento, independente do grupo, levou, no mínimo, sete dias e, no máximo, 14. Quanto ŕ aplicabilidade, o gel demonstrou melhor adesăo nas feridas e preenchimento do produto no subcutâneo de forma mais efetiva que o açúcar granulado. Conclui-se que tanto o gel quanto o açúcar foram efetivos na cicatrizaçăo das feridas dos animais deste experimento, sendo que o gel demonstrou precocidade na retraçăo cicatricial nos primeiros sete dias.Sugar is one of the most widely used products in the treatment of wounds in veterinary medicine. Its main advantage is the hygroscopic effect on tissues and the bacterial death by plasmolysis, making it a bactericidal agent due to the physical effect observed, without leading to bacterial resistance. The aim of this experiment was to compare cicatricial evolution of cutaneous wounds with the topical use of sugar either granulated or as gel. Sixteen canine wounds were treated: eight with granulated sugar (group A and eight with sugar gel (group G. Treatment time, independent of the group, took at least seven days and a maximum of 14. Concerning applicability, gel sugar showed better adhesion to wounds and subcutaneous filling more effectively that granulated sugar. It is concluded that both granulated and gel sugar were effective in healing skin wounds, the gel being precocious in cicatricial retraction within the first seven days of treatment.
Influence of colloidal silicon dioxide on gel strength, robustness, and adhesive properties of diclofenac gel formulation for topical application.
Lu, Zheng; Fassihi, Reza
The objective of this study is to identify the extent of stiffness, adhesiveness, and thixotropic character of a three-dimensional gel network of a 1% diclofenac sodium topical gel formulation in the presence and absence of colloidal silicon dioxide (CSD) and assess its ease of application and adhesiveness using both objective and subjective analysis. The 1% diclofenac gel was mixed with different amounts of CSD (e.g., 0.5, 1, 2, 3, and 5% w/w) and allowed to equilibrate prior to testing. The texture analyzer in combination with a cone-cap assembly was used to objectively investigate the changes in spreadability and adhesiveness of the gel system before and after addition of CSD. Results indicate that an increase in pliability and adhesiveness at levels ?2 to ?5% w/w of CSD dispersed in the gel ensues. For subjective analysis, gels with (2% w/w) CSD and in the absence of CSD were uniformly applied to a 20-cm(2) (5 cm?×?4 cm) surface area on the forearms of healthy volunteers and vehicle preferences by the volunteers regarding ease of application, durability on the skin, compliance, and feelings concerning its textural properties were assessed. It appears that changes in the gel formulation with the addition of CSD enhance gel viscosity and bonding to the skin. Results further show that changes in physical and rheological characteristics of gel containing 2% w/w CSD did not significantly change subject preferences for the gel preparations. These findings may help formulators to have additional options to develop more robust and cost-effective formulations. PMID:25501873
Detección de Mycobacterium avium subespecie paratuberculosis, por medio de PCR-anidada a partir de muestras de heces de ovinos / Detection of Mycobacterium avium subspecies paratuberculosis by nested-PCR of ovine fecal samples
Scientific Electronic Library Online (English)
Norma G, Jaimes; Marco Antonio, Santillán Flores; Oscar A, Hernández Cruz; Dionisio, Córdova López; Claudia Celic, Guzmán Ruiz; Beatriz, Arellano Reynoso; Efrén, Díaz Aparicio; Víctor R, Tenorio Gutiérrez; Alfredo, Cuéllar Ordaz.
Full Text Available La paratuberculosis es una enteritis granulomatosa de curso crónico ocasionada por Mycobacterium avium subespecie paratuberculosis (Map), afecta a rumiantes domésticos y silvestres. Map es excretada en las heces de animales que desarrollan la enfermedad, y la transmisión de la infección se da median [...] te la ingestión de alimentos y agua contaminados por heces de animales infectados. Con el objetivo de establecer el diagnóstico de paratuberculosis en ovinos por medio de la PCR-anidada a partir de muestras de heces, se trabajaron 204 muestras de heces y sueros de ovinos; las heces se evaluaron por PCR-anidada y cultivo bacteriológico, las muestras de sueros fueron analizadas por medio de inmunodifusión en agar gel (lDGA). Con la PCR-anidada se obtuvo un producto de amplificación 210 pb que corresponde a la IS900 de Map, en 61 de las 204 muestras. De éstas, 43 eran de animales positivos a IDGA y 18 negativos. Mediante cultivo bacteriológico se aislaron 17 cepas de Map; en este contexto, la IDGA detectó a 91 animales como positivos. La PCR-anidada permitió detectar en menor tiempo a mayor cantidad de animales que estaban eliminando al bacilo, aun cuando habían resultado negativos a la prueba serológica; este resultado se considera importante, ya que generalmente estos animales, al permanecer dentro de la granja, constituyen la principal fuente de infección para el rebańo. Se debe considerar a la PCR-anidada como alternativa, cuando se requiera el diagnóstico en breve tiempo, para conocer el estado sanitario del rebańo con respecto a paratuberculosis. Abstract in english Paratuberculosis is a chronic granulomatous enteritis caused by Mycobacterium avium subspecies paratuberculosis (Map), which affects wild and domestic ruminants. Map is shed in feces from infected animals. Transmission of the infection takes place by oral ingestion of the bacterium from contaminated [...] food and water with feces. With the objective to establish a paratuberculosis diagnosis in ovine by nested-PCR from fecal samples, 204 fecal and serum ovine samples were studied. Feces were evaluated by nested-PCR and bacterial culture, serum samples were analyzed by agar gel immunodiffusion (AGID). Nested-PCR yielded a 210 bp amplification product that corresponds to Map-IS900, in 61 out of 204 samples. From these, 43 were from AGID positive animals and 18 from negative animals. Seventeen Map strains were isolated by bacterial culture and AGID detected 91 positive animals. Nested-PCR allowed to detect, sooner, greater number of animals shedding bacillus, even when they had resulted negative to the serological test. This result is considered important because generally these animals, while remaining in the farm, constitute the main source of infection for the herd. Nested-PCR should be considered as an alternative, when a prompt result is required to know the health status of the herd with respect to paratuberculosis.
Time and frequency dependent rheology of reactive silica gels.
Wang, Miao; Winter, H Henning; Auernhammer, Günter K
In a mixture of sodium silicate and low concentrated sulfuric acid, nano-sized silica particles grow and may aggregate to a system spanning gel network. We studied the influence of the finite solubility of silica at high pH on the mechanical properties of the gel with classical and piezo-rheometers. Direct preparation of the gel sample in the rheometer cell avoided any pre-shear of the gel structure during the filling of the rheometer. The storage modulus of the gel grew logarithmically with time with two distinct growth laws. The system passes the gel point very quickly but still shows relaxation at low frequency, typically below 6 rad/s. We attribute this as a sign of structural rearrangements due to the finite solubility of silica at high pH. The reaction equilibrium between bond formation and dissolution maintains a relatively large bond dissolution rate, which leads to a finite life time of the bonds and behavior similar to physical gels. This interpretation is also compatible with the logarithmic time dependence of the storage modulus. The frequency dependence was more pronounced for lower water concentrations, higher temperatures and shorter reaction times. With two relaxation models (the modified Cole-Cole model and the empirical Baumgaertel-Schausberger-Winter model) we deduced characteristic times from the experimental data. Both models approximately described the data and resulted in similar relaxation times. PMID:24183445
Study of lanthanide complexes in silica gels by photoacoustic spectroscopy
International Nuclear Information System (INIS)
Via a sol-gel process, lanthanide complexes Ln(bipy)2Cl3.2H2O (Ln3+:La3+, Nd3+, Tb3+; bipy: 2,2'-bipyridyl) are incorporated into silica gels by the hydrolysis and condensation of tetraethoxysilane (TEOS). Upon heat treatment at 150 deg. C, PA intensity of the ligand increases for Tb3+, La3+ and Nd3+ complexes in silica gels, respectively, while this difference cannot be observed for samples without heat treatment. Different PA intensities of lanthanide complexes in silica gels are interpreted by comparison with their luminescence spectra. Spectral results indicate that bipy does not coordinate with lanthanide ions in gels without a suitable heat treatment. The formation of lanthanide complexes in silica gels is discussed from two aspects: radiative and non-radiative processes firstly. The nephelauxetic parameters and PA branching vectors of f-f transitions of Nd3+ complex in silica gels, which exhibit highly sensitivity to the coordination environment, are also discussed
Structure and dynamics of a nanocolloidal silica gel dispersion
International Nuclear Information System (INIS)
We studied the structure and the dynamics of a nanocolloidal silica gel dispersed in an organic solvent [octylcyanobiphenyl (8CB)] as a function of the silica density by x-ray intensity fluctuation spectroscopy (XIFS). The silica density of the dispersed aerosil gel samples ranged from 0.03 to 0.20 g cm-3 and the autocorrelation of the silica scattering was probed over the q range from 0.03 to 0.15 nm-1 (corresponding to length scales from 42 to 209 nm) at a constant room temperature at which 8CB is in the smectic-A phase. The gel structure has a fractal dimension in this density range of df?2.15. The time autocorrelation functions of the gels show clear density-dependent and complex dynamics. The gel relaxation times are very long and become bimodal with nonergodic character for densities from 0.10 to 0.16 g cm-3. In this same density range, the fluctuation contrast (strength) is a minimum while the relaxation time becomes independent of wave vector. Together, these results indicate that there is a narrow silica density range for these gels in which the dynamics changes dramatically. This suggests a complex phase diagram for the dynamics of aerosil gels as a function of densification
Soft magnetorheological polymer gels with controllable rheological properties
Xu, Yangguang; Gong, Xinglong; Xuan, Shouhu
A series of magnetorheological (MR) gels consisting of plastic polyurethane matrix swollen by nonvolatile solvent in different weight fractions and carbonyl iron particles were prepared. Their magnetorheological properties, both under oscillatory and rotational shear rheometry, were systematically tested. The results demonstrate that except for the significant influence on the magnetorheological performance, the state of these MR gels can also be easily switched from solid-like (the solvent content is less than 10 wt%) to liquid-like (the solvent content exceeds 25 wt%) by adjusting the solvent content. The huge differences in magnetorheological properties of different MR gels (for example, the G? of MR gels without solvent is three orders of magnitude larger than that of MR gels with 45 wt% of solvent in the absence of a magnetic field) and movements of iron particles in the presence of a magnetic field were analyzed, which are helpful in thoroughly understanding the mechanical-magnetic coupling mechanism between the magnetic particles and the polymer matrix and promoting the application of MR polymer gels. In addition, the stability of MR gels was also investigated. A gravity yield parameter was introduced to quantitatively describe the relationship between particle sedimentation and material characteristics. When the solvent content is lower than 25 wt% or the gravity yield parameter is larger than 0.865, the particle settling phenomenon can be effectively avoided.
Development of mucoadhesive sprayable gellan gum fluid gels.
Mahdi, Mohammed H; Conway, Barbara R; Smith, Alan M
The nasal mucosa provides a potentially good route for local and systemic drug delivery. However, the protective feature of the nasal cavity make intranasal delivery challenging. The application of mucoadhesive polymers in nasal drug delivery systems enhances the retention of the dosage form in the nasal cavity. Several groups have investigated using low acyl gellan as a drug delivery vehicle but only limited research however, has been performed on high acyl gellan for this purpose, despite its properties being more conducive to mucoadhesion. High acyl gellan produces highly elastic gels below 60°C which make it difficult to spray using a mechanical spray device. Therefore, in this study we have tried to address this problem by making fluid gels by introducing a shear force during gelation of the gellan polymer. These fluid gel systems contain gelled micro-particles suspended in a solution of un-gelled polymer. These systems can therefore behave as pourable viscoelastic fluids. In this study we have investigated the rheological behavior and mucoadhesion of fluid gels of two different types of gellan (high and low acyl) and fluid gels prepared from blends of high and low acyl gellan at a 50:50 ratio. The results demonstrated that by preparing fluid gels of high acyl gellan, the rheological properties were sufficient to spray through a standard nasal spray device. Moreover fluid gels also significantly enhance both high acyl and low acyl gellan mucoadhesion properties. PMID:25863119
Development of an injectable chitosan/marine collagen composite gel
Energy Technology Data Exchange (ETDEWEB)
Wang Wei [Department of Inorganic Materials, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062 (Japan); Itoh, Soichiro [Affiliated Facility for Clinical and Fieldwork Practices, International University of Health and Welfare, 6-1-14 Kounodai, Ichikawa-shi, Chiba 272-0827 (Japan); Aizawa, Tomoyasu; Demura, Makoto [Division of Molecular Life Science, Graduate School of Life Science, Hokkaido University, Sapporo 060-0810 (Japan); Okawa, Atsushi [Department of Orthopaedic and Spinal Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519 (Japan); Sakai, Katsuyoshi; Ohkuma, Tsuneo, E-mail: firstname.lastname@example.com [Research and Development Division, Hokkaido Soda Co., Ltd, 2-12 Chitose, Noboribetsu-shi 059-0003 (Japan)
A chitosan/marine-originated collagen composite has been developed. This composite gel was characterized and its biocompatibility, as well as an inflammatory reaction, was observed. The chitosan gel including N-3-carboxypropanoil-6-O-(carboxymethyl) chitosan of 3 mol%, 6-O-(carboxymethyl) chitosan of 62 mol% and 6-O-(carboxymethyl) chitin of 35 mol% was prepared and compounded with the salmon atelocollagen (SA) gel at different mixture ratios. The composite gels were injected subcutaneously in to the back of rats. The specimens were harvested for a histological survey as well as a tumor necrosis factor-alpha (TNF-{alpha}) assay by ELISA. The inflammatory cell infiltration and release of TNF-{alpha} were successively controlled low with the ratio of SA to chitosan at 10:90 or 20:80. The SA gel first, within 2 weeks, and then chitosan in the composite gel were slowly absorbed after implantation, followed by soft tissue formation. It is expected that this composite gel will be available as a carrier for tissue filler and drug delivery systems.
Western Blot of Stained Proteins from Dried Polyacrylamide Gels
Gruber, Claudia; Stan-Lotter, Helga
Western blotting of proteins is customarily performed following their separation on polyacrylamide gels, either prior to staining (1) or, as recently reported, following staining (2). We describe here Western blotting with stained gels, which had been dried and some of which had been stored for years. This procedure permits immunological analysis of proteins, to which antisera may have become available only later, or where the application of newly developed sensitive detection methods is desired. Once rehydration of the gels is achieved, proteins can be-transferred to blotting membranes by any appropriate protocol. Proteins stained with Coomassie Blue have to be detected with a non-chromogenic method, such as the film-based enhanced chemiluminescence (ECL)2) procedure (3). Silver stained proteins, which transfer in the colorless form, may be visualized by any detection method, although, because of the usually very low amounts of proteins, detection by ECL is preferable. Blotting of stained proteins from rehydrated gels is as rapid and as quantitative as from freshly prepared gels, in contrast to blotting from wet stained gels, which requires extensive washing and results in low transfer efficiency (2). Together with a photographic record of the gel pattern, unambiguous identification of immunoreactive proteins from complex mixtures is possible. Some further applications of this work are discussed.
Development of an injectable chitosan/marine collagen composite gel
International Nuclear Information System (INIS)
A chitosan/marine-originated collagen composite has been developed. This composite gel was characterized and its biocompatibility, as well as an inflammatory reaction, was observed. The chitosan gel including N-3-carboxypropanoil-6-O-(carboxymethyl) chitosan of 3 mol%, 6-O-(carboxymethyl) chitosan of 62 mol% and 6-O-(carboxymethyl) chitin of 35 mol% was prepared and compounded with the salmon atelocollagen (SA) gel at different mixture ratios. The composite gels were injected subcutaneously in to the back of rats. The specimens were harvested for a histological survey as well as a tumor necrosis factor-alpha (TNF-?) assay by ELISA. The inflammatory cell infiltration and release of TNF-? were successively controlled low with the ratio of SA to chitosan at 10:90 or 20:80. The SA gel first, within 2 weeks, and then chitosan in the composite gel were slowly absorbed after implantation, followed by soft tissue formation. It is expected that this composite gel will be available as a carrier for tissue filler and drug delivery systems.
Creating coordination-based cavities in a multiresponsive supramolecular gel.
Wei, Shi-Chao; Pan, Mei; Fan, Yuan-Zhong; Liu, Haoliang; Zhang, Jianyong; Su, Cheng-Yong
Creating cavities in varying levels, from molecular containers to macroscopic materials of porosity, have long been motivated for biomimetic or practical applications. Herein, we report an assembly approach to multiresponsive supramolecular gels by integrating photochromic metal-organic cages as predefined building units into the supramolecular gel skeleton, providing a new approach to create cavities in gels. Formation of discrete O-Pd2 L4 cages is driven by coordination between Pd(2+) and a photochromic dithienylethene bispyridine ligand (O-PyFDTE). In the presence of suitable solvents (DMSO or MeCN/DMSO), the O-Pd2 L4 cage molecules aggregate to form nanoparticles, which are further interconnected through supramolecular interactions to form a three-dimensional (3D) gel matrix to trap a large amount of solvent molecules. Light-induced phase and structural transformations readily occur owing to the reversible photochromic open-ring/closed-ring isomeric conversion of the cage units upon UV/visible light radiation. Furthermore, such Pd2 L4 cage-based gels show multiple reversible gel-solution transitions when thermal-, photo-, or mechanical stimuli are applied. Such supramolecular gels consisting of porous molecules may be developed as a new type of porous materials with different features from porous solids. PMID:25876958
Chemically responsive gels prepared from microspheres dispersed in liquid crystals.
Pal, Santanu Kumar; Agarwal, Ankit; Abbott, Nicholas L
Liquid-crystalline materials are a promising class of stimuli-responsive materials that have been demonstrated to undergo surface-induced orientational ordering transitions that can be highly sensitive and specific to chemical species. However, past studies demonstrating surface-induced transitions in liquid crystals (LCs) have employed thin films of low-molecular-weight LCs that are difficult to stabilize (due to dewetting of the LC on a surface). Here, it is reported that it is possible to prepare liquid-crystalline gels using a mixture of polystyrene microspheres and nematic LCs that undergo changes in orientational order, and thus optical appearance, in response to exposure to specific chemical compounds. These colloid-in-liquid-crystal (CLC) gels are mechanically stable and can be molded on chemically functionalized surfaces into thin films containing micrometer-sized LC-rich domains that span the two interfaces of the gels. In contrast to other reports of LC gels, where the presence of a polymeric or self-assembled small-molecule gelator network within a nematic LC frustrates ordering transitions from propagating through the gels over distances, it is demonstrated that thin films of CLC gels, when supported on chemically functionalized surfaces, do undergo easily visualized ordering transitions upon exposure to organophosphonate compounds. Because these optically responsive CLC gels are mechanically robust and can be molded, this class of composite LC material may be broadly useful for the design of chemically responsive LC devices. PMID:19777464
Implementation of MRI gel dosimetry in radiation therapy
Energy Technology Data Exchange (ETDEWEB)
Baeck, S.Aa.J
Gel dosimetry was used together with magnetic resonance imaging (MRI) to measure three-dimensional absorbed dose distributions in radiation therapy. Two different dosimeters were studied: ferrous- and monomer gel, based on the principles of radiation-induced oxidation and polymerisation, respectively. Single clinical electron and photon beams were evaluated and gel dose distributions were mainly within 2% of conventional detector results. The ferrous-gel was also used for clinical proton beams. A decrease in signal per absorbed dose was found close to the end of the range of the protons (15-20%). This effect was explained as a linear energy transfer dependence, further supported with Monte Carlo simulations. A method for analysing and comparing data from treatment planning system (TPS) and gel measurements was developed. The method enables a new pixel by pixel evaluation, isodose comparison and dose volume histogram verification. Two standard clinical radiation therapy procedures were examined using the developed TPS verification method. The treatment regimes included several beams of different radiation qualities. The TPS calculated data were in very good agreement with the dose distribution measured by the ferrous-gel. However, in a beam abutment region, larger dose difference was found. Beam adjustment errors and a minor TPS underestimation of the lateral scatter contribution outside the primary electron beam may explain the discrepancy. The overall uncertainty in the ferrous-gel dose determination was considerably reduced using an optimised MRI acquisition protocol and a new MRI scanner. The relative dose uncertainty was found to be better than 3.3% for all dose levels (95% confidence level). Using the method developed for comparing measured gel data with calculated treatment plans, the gel dosimetry method was proven to be a useful tool for radiation treatment planning verification 103 refs, 20 figs, 6 tabs
Implementation of MRI gel dosimetry in radiation therapy
International Nuclear Information System (INIS)
Gel dosimetry was used together with magnetic resonance imaging (MRI) to measure three-dimensional absorbed dose distributions in radiation therapy. Two different dosimeters were studied: ferrous- and monomer gel, based on the principles of radiation-induced oxidation and polymerisation, respectively. Single clinical electron and photon beams were evaluated and gel dose distributions were mainly within 2% of conventional detector results. The ferrous-gel was also used for clinical proton beams. A decrease in signal per absorbed dose was found close to the end of the range of the protons (15-20%). This effect was explained as a linear energy transfer dependence, further supported with Monte Carlo simulations. A method for analysing and comparing data from treatment planning system (TPS) and gel measurements was developed. The method enables a new pixel by pixel evaluation, isodose comparison and dose volume histogram verification. Two standard clinical radiation therapy procedures were examined using the developed TPS verification method. The treatment regimes included several beams of different radiation qualities. The TPS calculated data were in very good agreement with the dose distribution measured by the ferrous-gel. However, in a beam abutment region, larger dose difference was found. Beam adjustment errors and a minor TPS underestimation of the lateral scatter contribution outside the primary electron beam may explain the discrepancy. The overall uncertainty in the ferrous-gel dose determination was considerably reduced using an optimised MRI acquisition protocol and a new MRI scanner. The relative dose uncertainty was found to be better than 3.3% for all dose levels (95% confidence level). Using the method developed for comparing measured gel data with calculated treatment plans, the gel dosimetry method was proven to be a useful tool for radiation treatment planning verification
Sol-gel processing with inorganic metal salt precursors
Hu, Zhong-Cheng
Methods for sol-gel processing that generally involve mixing together an inorganic metal salt, water, and a water miscible alcohol or other organic solvent, at room temperature with a macromolecular dispersant material, such as hydroxypropyl cellulose (HPC) added. The resulting homogenous solution is incubated at a desired temperature and time to result in a desired product. The methods enable production of high quality sols and gels at lower temperatures than standard methods. The methods enable production of nanosize sols from inorganic metal salts. The methods offer sol-gel processing from inorganic metal salts.
Azelaic acid (15% gel) in the treatment of acne rosacea.
Gupta, Aditya K; Gover, Melissa D
In December of 2002, the FDA approved azelaic acid 15% gel for the topical treatment of inflammatory papules and pustules of mild to moderate rosacea. Azelaic acid is a saturated dicarboxylic acid, which is naturally occurring and has been used in the treatment of rosacea, acne, and melasma. The 15% gel has a high efficacy and is generally well tolerated, with the local irritation (burning, stinging, itching, and scaling) being typically mild and transient. Azelaic acid 15% gel is considered effective and safe as a therapy for inflammatory papulo-pustular rosacea and is suitable for use on all skin types. PMID:17472690
Application and production of sol-gel process
International Nuclear Information System (INIS)
This book consists of eight chapters, which are deals with new chemistry of sol-gel process, creation of functional materials such as optical glass for laser, grin lens, nuclear fuel and ceramic, new complex materials by structure control such as intercalation and ORMOCERs, functional design, application and advance of analysis technology application of special technology on sol-gel process like supercritical dry and electrophoresis assay, development situation in Japan and development on sol-gel process about the accumulation of technology for present, and future.
Interaktion mellem warfarin og oral miconazol-gel
DEFF Research Database (Denmark)
Ogard, C G; Vestergaard, Henrik
We report a case of a 76 year-old woman who had been taking warfarin for seven years because of relapsing deep venous thrombosis. Her daily maintenance dose was 5 mg. Monthly measurements of international normalised ratio (INR) were stable between 2-3. She developed oral candidiasis and miconazole gel was prescribed. One week later she developed bleeding gums. Eight days later she was admitted to the hospital with haematuria. INR was > 10. Warfarin and the miconazole gel were withdrawn. She was treated with phytonadione. INR normalised after four days and she continued warfarin treatment. Caution should be exercised whenever the combination of warfarin and miconazole gel are prescribed.
Effect of Electron beam on Prepared HAP-Gel Composition
Directory of Open Access Journals (Sweden)
Naima A. El Gendy*,Tawfik M. S.**, and Asma M. Nour
Full Text Available Background: Polyvinyl alcohol liquid PVAl was used as the organic carrier for Hydroxylapatite-gel (Hap-gel composite. PVAl has the ability to form a nano- hydroxylapatite polyvinyl alcohol composite gel which has a wide range of uses in different environmental and medical applications. Prepared Hap-gel is known to have a very similar composition to human bone and is used as a substitute for bones in compound fractures and artificial dentures. Matreia and Methods: In this work prepared HAP- gel was exposed to a high ionizing radiation electron beam (5 kilo Gray and an aqueous solution containing aluminum ions (Al+. Some investigations were done to illustrate the effect of radiation exposure and aluminum contamination on prepared Hap-gel. Results: Energy dispersive X-ray analysis (EDx showed that the electron beam used caused an obvious increase in the calcium ions (Ca++ content of the prepared Hap-gel from 60% to 65.69 % with a prominent decrease in phosphorus ions (P + content from 40 % to 34.31 % in addition to an increase in the Ca/P ratio from 1.5 to 1.91. Exposure of the pre-irradiated Hap-gel samples to aluminium ions (Al+ resulted in a noticeable decrease in Ca++ content from 65.69 atomic % to 32.14 % atomic % and a further noticeable decrease in P+ content from 34.31 % atomic % to 13 atomic % as well as an increase in the Ca/P ratio from 1.91 to 2.47. The levels for the original prepared Hap-gel were Ca++; 60 atomic % and P+; 40 atomic %. It was deduced that exposure of the Hap-gel to Al+ had a further damaging effect on the pre-irradiated Hap-gel composition in addition to the damaging effect that the electron beam used induced on the samples. Conclusions: it could be concluded that electron beams and Al+ have an injurious effect on human bone tissue taking into consideration the similarity in composition between Hap-gel and bones. Therefore, this study could be beneficial in the field of osteoporosis research and assist the understanding of the effects of radiation such as that of electron beams and some pollutants such as aluminium present in running water on the health of human bone tissue.
Orientation of the agarose gel matrix in pulsed electric fields.
Stellwagen, J.; Stellwagen, N. C.
The technique of transient electric birefringence was used to investigate the effect of pulsed electric fields on the orientation of the agarose gel matrix. Orientation of the gel was observed at all electric field strengths. Very slow, time-dependent effects were observed when pulses of 10-100 V/cm were applied to 1% gels for 0.5-2 seconds, indicating that domains of the matrix were being oriented by the electric field. The sign of the birefringence reversed when the direction of the applied...
Fracture of a biopolymer gel as a viscoplastic disentanglement process
Baumberger, T; Martina, D; Baumberger, Tristan; Caroli, Christiane; Martina, David
We present an extensive experimental study of mode-I, steady, slow crack dynamics in gelatin gels. Taking advantage of the sensitivity of the elastic stiffness to gel composition and history we confirm and extend the model for fracture of physical hydrogels which we proposed in a previous paper (Nature Materials, doi:10.1038/nmat1666 (2006)), which attributes decohesion to the viscoplastic pull-out of the network-constituting chains. So, we propose that, in contrast with chemically cross-linked ones, reversible gels fracture without chain scission.
Directory of Open Access Journals (Sweden)
T. Mangilal*, K. S. K. Rao Patnaik , R. Sivakumar , Y. Sudhakar and S. K. Basu
Full Text Available Povidone-Iodine Ointment was prepared using polyethylene glycol base by fusion method and the gel was prepared using Poloxamer 407 as a gelling agent by cold process. The different characteristics of povidone-iodine ointment and gel were compared from the results obtained for assay and total, available and complex iodine contents. These values were comparable with marketed formulations. The formulations were tested for wound healing and antimicrobial activity. Wound healing studies show that the time taken for complete wound healing was slightly less for prepared povidone-iodine ointment and gel than the marketed preparations. Antimicrobial activity also found to be almost equal for the different formulations.
Gels and gel-derived glasses in the Na2O-B2O3-SiO2 system. [containerless melting in space
Mukherjee, S. P.
The containerless melting of high-purity multicomponent homogeneous gels and gel-monoliths offers a unique approach to making ultrapure multicomponent optical glasses in the reduced gravity environment of space. Procedures for preparing and characterizing gels and gel-derived glasses in the Na2O-B2O3-SiO2 system are described. Preparation is based on the polymerization reactions of alkoxysilane with trimethyl borate or boric acid and a suitable sodium compound. The chemistry of the gelling process is discussed in terms of process parameters and the gel compositions. The physicochemical nature of gels prepared by three different procedures were found to be significantly different. IR absorption spectra indicate finite differences in the molecular structures of the different gels. The melting of the gel powders and the transformation of porous gel-monoliths to transparent 'glass' without melting are described.
Gels and gel-derived glasses in the system Na2O-B2O3-SiO2
Mukherjee, S. P.
The containerless melting of high-purity multicomponent homogeneous gels and gel monoliths offers a unique approach to making ultrapure multicomponent optical glasses in the reduced gravity environment of space. Procedures for preparing and characterizing gels and gel-derived glasses in the system Na2O-B2O3-SiO2 are described. Preparation is based on the polymerization reactions of alkoxysilane with trimethyl borate or boric acid and a suitable sodium compound. The chemistry of the gelling process is discussed in terms of process parameters and the gel compositions. The physicochemical nature of gels prepared by three different procedures was found to be significantly different. Infrared absorption spectra indicate finite differences in the molecular structures of the different gels. The melting of the gel powders and the transformation of porous gel monoliths to transparent 'glass' without melting are described.
Clotrimazole nanoparticle gel for mucosal administration.
Esposito, Elisabetta; Ravani, Laura; Contado, Catia; Costenaro, Andrea; Drechsler, Markus; Rossi, Damiano; Menegatti, Enea; Grandini, Alessandro; Cortesi, Rita
In this study a formulation suitable to be applied on oral and/or vaginal mucosa has been developed for the treatment of fungal infections. The aim of the research is a comparison between clotrimazole (CLO) containing semisolid formulations based on monoolein aqueous dispersion (MAD) or nanostructured lipid carrier (NLC). MAD and NLC have been characterized in terms of morphology and dimensional distribution by cryogenic Transmission Electron Microscopy (cryo-TEM) and Photon Correlation Spectroscopy (PCS). CLO was encapsulated with high entrapment efficiency both in MAD and in NLC, according to Sedimentation Field Flow Fractionation (SdFFF) combined with HPLC. CLO recovery in MAD and NLC has been investigated by time. In order to obtain formulations with suitable viscosity for mucosal application, MAD was diluted with a carbomer gel, while NLC was directly viscosized by the addition of poloxamer 407 in the dispersion. The rheological properties of MAD and NLC after viscosizing have been investigated. Franz cell has been employed to study CLO diffusion from the different vehicles, evidencing diffusion rates from MAD and NLC superimposable to that obtained using Canesten(®). An anticandidal activity study demonstrated that both CLO-MAD and CLO-NLC were more active against Candida albicans with respect to the pure drug. PMID:25428089
Drying and shrinkage of polymer gels
Scientific Electronic Library Online (English)
S. S., Waje; M. W., Meshram; V., Chaudhary; R., Pandey; P. A., Mahanawar; B. N., Thorat.
Full Text Available The polymer hydrogel was synthesized by photo-polymerization process (UV light, 60 şC) in presence of Photo-initiator (IrgacureR) and Cross-linker (NN'-methylene bisacrylamide; MBAM). In the present work, the drying of polymer hydrogel was carried out to study the effect of temperature, gel-sheet th [...] ickness, monomer ratio of acryl acid to acrylamide (AA/AM), concentration of MBAM and quantity of monomers. A correlation has been developed for modified sheet thickness as a function of contraction coefficient and degree of drying. Effective diffusivity was estimated from Fickian-diffusive model considering modified sheet thickness and was found to be in the range of 1.1 ´ 10-10-5.93 ´ 10-10 m˛/s. The activation energy obtained using Arrhenius type equation was found to be in the range of 2979-10737 kJ/kmol H2O. The drying behavior shows an initial shoot-up in drying rate followed by constant rate and two falling rate periods.
Drying and shrinkage of polymer gels
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S. S. Waje
Full Text Available The polymer hydrogel was synthesized by photo-polymerization process (UV light, 60 şC in presence of Photo-initiator (IrgacureR and Cross-linker (NN'-methylene bisacrylamide; MBAM. In the present work, the drying of polymer hydrogel was carried out to study the effect of temperature, gel-sheet thickness, monomer ratio of acryl acid to acrylamide (AA/AM, concentration of MBAM and quantity of monomers. A correlation has been developed for modified sheet thickness as a function of contraction coefficient and degree of drying. Effective diffusivity was estimated from Fickian-diffusive model considering modified sheet thickness and was found to be in the range of 1.1 ´ 10-10-5.93 ´ 10-10 m˛/s. The activation energy obtained using Arrhenius type equation was found to be in the range of 2979-10737 kJ/kmol H2O. The drying behavior shows an initial shoot-up in drying rate followed by constant rate and two falling rate periods.
Casting AISI 316 steel by gel cast
International Nuclear Information System (INIS)
The feasibility of producing AISI 316 steel components from their powders and avoiding their compaction is analyzed. A casting technique is tested that is similar to gel casting, used for ceramic materials. In the initial stage, the process consists of the formulation of a concentrated barbotine of powdered metal in a solution of water soluble organic monomers, which is cast in a mold and polymerized in situ to form a raw piece in the shape of the cavity. The process can be performed under controlled conditions using barbotines with a high monomer content from the acrylimide family. Then, the molded piece is slowly heated until the polymer is eliminated, and it is sintered at temperatures of 1160oC to 1300oC under a dry hydrogen atmosphere, until the desired densities are attained. The density and micro structure of the materials obtained are compared with those for the materials compacted and synthesized by the conventional processes. The preliminary results show the feasibility of the process for the production of certain kinds of structural components (CW)
Serological Evaluation of Brucella abortus S99 Lipopolysaccharide Extracted by an Optimized Method
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Ali S. Salmani
Full Text Available Problem statement: Brucellosis is a globally found infectious disease and there is no licensed vaccine against human brucellosis. The present study carried-out to evaluate the potency of our modified extracted lipopolysaccharide (LPS of B. abortus to elicit specific anti-Brucella antibodies in animal model (Rabbit as a part of a candidate vaccine for brucellosis. Lipopolysaccharide is one of the main virulence factors and the most immunogenic structure of smooth strains of Brucella. Approach: Lipopolysaccharide of B. abortus S99 (S-LPS initially extracted through an optimized method as described previously. After biochemical and pyrogenicity evaluations of the extracted S-LPS humoral immune response against the extracted LPS analyzed in animal model through serological assays such as Rose Bengal assay, Rapid agglutination (Rapid Wright test and Standard agglutination test (SAT or Wright test to demonstrate the specific elicited antibodies against the injected LPS. In addition, the interaction of LPS and anti-LPS antibodies was demonstrated by Agarose Gel Immunodiffusion (AGID assay. Results: Higher doses of B. abortus S99 LPS caused less or equal body temperature increase in comparison to E. coli LPS doses. Sera of immunized animals had been reported positive by RBT because of B. abortus LPS immunogenicity which we extracted through our optimized method. The highest titer of anti-Brucella antibodies detected two weeks after the third immunization (assayed by rapid slide agglutination and standard agglutination tests. Anti-Brucella antibodies of immunized animals reacted more specifically with the LPS of B. abortus in comparison with E. coli LPS and precipitation lines between B. abortus LPS and immune sera appeared after 30 min while detected after three hours for E. coli LPS. Conclusions/Recommendations: The properties of B. abortus S99 LPS concluded from the present study results, suggest the possible use of this component as a carrier or a part of a sub-unit or conjugated vaccine for human brucellosis.
Directory of Open Access Journals (Sweden)
Full Text Available The efficiency of Peste des petits ruminants virus (PPRV vaccines available in Pakistan was evaluated on the basis of the humoral immune response measured by haemagglutination inhibition (HI and agar gel immunodiffusion (AGID tests in sheep (n=60 and goats (n=60. The effect of storage temperature on HA activity of vaccine virus was measured by holding the vaccine at -20, 4, 27 and 40°C for 24 hours. The titer of freshly prepared vaccine was 1:16 and remained unchanged for 24 hours in the vaccines stored at -20 and 4°C. However, drop in titer (1:2 HA was recorded in the vaccine kept at 40°C for 24 hours. The haemagglutination activity of PPR virus constituted in buffer with pH 6.8 and 7.0 was recorded as highest when assay was performed with chicken and human blood group'O' erythrocytes (1%. The lowest titer was recorded when vaccine was reconstituted in buffer at pH 8.0. After 14th day post vaccination, there was a gradual increase in the antibody titer till 56th day. Geometric mean titer (GMT of antibodies against locally manufactured PPRV vaccine was higher (207.9 in comparison with Pestivec (73.3, a vaccine imported from Jordan at 63rd day post vaccination in sheep; the corresponding values in goats were 147.0 and 48.5, respectively. All animals of control group were negative for antibodies by both of the diagnostic tests.
Photosensitive YBCO gel film and its patterning by sol-gel process
Zhang, Huangli; Zhao, Gaoyang
The YBCO precursor solution was prepared using yttrium acetate, barium acetate and copper acetate as starting material, diethylenetriamine, trifluoroacetate, acrylic acid (AA) as chemical additives, methanol as solvent. The precursor solution was modified by AA, in which the Cu 2+ of Cu(OAc) 2 and AA were reacted to form the photosensitive copper complex. The coated gel film using this precursor solution exhibited the photosensitivity to UV light at around 245 nm. Utilizing the photosensitivity, the patterned YBCO film with a high critical transition temperature ( Tc) of 91.5 K was fabricated.
Bi-Sr-Co-O thermoelectrics prepared by sol-gel methods with modified gel decomposition.
Czech Academy of Sciences Publication Activity Database
Rubešová, K.; Hlásek, T.; Jakeš, V.; Sedmidubský, D.; Hejtmánek, Ji?í
Ro?. 30, ?. 1 (2012), 1-5. ISSN 1757-8981. [Fall Meeting of the European-Materials-Research-Society (E-MRS)/Symposium K - Solution-Derived Electronic-Oxide Films, Nanostructures and Patterning, from Materials to Devices. Warsaw, 19.09.2011-23.09.2011] R&D Projects: GA ?R GA203/09/1036 Institutional research plan: CEZ:AV0Z10100521 Keywords : BiSrCoO * thermoelectrics * sol–gel Subject RIV: BM - Solid Matter Physics ; Magnetism
Gel electrolytes based on lithium modified silica nano-particles
International Nuclear Information System (INIS)
In this work lithium modified silica (Li-SiO2) nano-particles were synthesized and used as a single ion lithium conductor source in gel electrolytes. It was found that Li-SiO2 exhibited good compatibility with DMSO, DMA/EC (a mixture of N,N-dimethyl acetamide and ethylene carbonate) and the ionic liquid, N-methyl-N-propyl pyrrolidinium bis(trifluoromethylsulfonyl) amide ([C3mpyr][NTf2]). Several gel electrolytes based on Li-SiO2 were obtained. These gel electrolytes were investigated by DSC, solid state NMR, conductivity measurements and cyclic voltammetry. Conductivities as high as 10-3 S/cm at room temperature were observed in these nano-particle gel electrolytes. The results of electrochemical tests showed that some of these materials were promising for using as lithium conductive electrolytes in electrochemical devices, with high lithium cycling efficiency evident
formulation and evaluation of topical gel of aceclofenac
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tarun kumar guleri
Full Text Available Topical gel formulations of Aceclofenac were prepared using these polymers such as Carbopol?934, Carbopol?941, HPMC, Poloxamer 407 in different concentration for the treatment of rheumatoid arthritis. The gels were evaluated for various parameters such as homogeneity, grittiness, skin irritancy, extrudability, in vitro drug release, viscosity(Brooke field viscometer, pH, drug content, stability studies. The in vitro release rate of gel was evaluated using Franz diffusion cell containing cellophane membrane with phosphate buffer pH 7.4 as the receptor medium. The release rate of the gel was found to obey Higuchi model. The percentage of drug release follow following order Poloxamer-407> HPMC> Carbopol-940>Carbopol-934.
Production of continuous mullite fiber via sol-gel processing
Tucker, Dennis S.; Sparks, J. Scott; Esker, David C.
The development of a continuous ceramic fiber which could be used in rocket engine and rocket boosters applications was investigated at the Marshall Space Flight Center. Methods of ceramic fiber production such as melt spinning, chemical vapor deposition, and precursor polymeric fiber decomposition are discussed and compared with sol-gel processing. The production of ceramics via the sol-gel method consists of two steps, hydrolysis and polycondensation, to form the preceramic, followed by consolidation into the glass or ceramic structure. The advantages of the sol-gel method include better homogeneity and purity, lower preparation temperature, and the ability to form unique compositions. The disadvantages are the high cost of raw materials, large shrinkage during drying and firing which can lead to cracks, and long processing times. Preparation procedures for aluminosilicate sol-gel and for continuous mullite fibers are described.
Preliminary Investigation of the Dosimetric Properties of 'RadGel'
International Nuclear Information System (INIS)
A preliminary investigation into the efficacy of a new 3D dosimetry material, RadGelTM, for verification of radiation therapy dose distributions is presented. Small volumes of RadGelTM were found to exhibit a linear, reproducible response to dose. A gradual increase in optical-density (OD) with time was observed, suggesting scanning should be completed within 18 hours to keep a linear correlation of R2 > 0.99. A larger 10 cm diameter volume of RadGelTM was irradiated with a rotationally symmetric 'spoke' plan designed to rigorously evaluate scanner/dosimeter combined performance. The dosimeter was imaged with the Duke Mid-sized Optical-CT Scanner (DMOS). Promising OD and corresponding dose maps were obtained. Edge artefacts were observed and are suspected to be exacerbated by the particular container used in this early study. Further studies will evaluate new containers and methods for refractive matching at the gel-container-fluid interface.
Studies on supramolecular gel formation using DOSY NMR.
Czech Academy of Sciences Publication Activity Database
Nonappa, N.; Šaman, David; Kolehmainen, E.
Ro?. 53, ?. 4 (2015), s. 256-260. ISSN 0749-1581 Institutional support: RVO:61388963 Keywords : DOSY * VT NMR * gel * diffusion coefficients Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.559, year: 2013
The substitute brain and the potential of the gel model.
Pomfret, Roland; Miranpuri, Gurwattan; Sillay, Karl
This purpose of this paper is to review the recent history of the use of agarose gels. Although originally confined to electrophoresis work, agarose gels have proven themselves useful to a number of disciplines in the modern world, which includes brain infusion studies for research involving the treatment of various neurological conditions, such as Parkinson's Disease. In reviewing the relevant research leading up to the modern day, this paper attempts to track agarose gels through their stages of accuracy verification, highlighting why they are useful to the neurosurgery discipline and characterizing the nature of their use. Agarose gels do have significant limitations, which are also discussed, but they have substantial potential as a modifiable medium or as a basis of comparison for even more accurate models in the future. PMID:25206029
Composition and applications of Aloe vera leaf gel.
Hamman, Josias H
Many of the health benefits associated with Aloe vera have been attributed to the polysaccharides contained in the gel of the leaves. These biological activities include promotion of wound healing, antifungal activity, hypoglycemic or antidiabetic effects antiinflammatory, anticancer, immunomodulatory and gastroprotective properties. While the known biological activities of A. vera will be briefly discussed, it is the aim of this review to further highlight recently discovered effects and applications of the leaf gel. These effects include the potential of whole leaf or inner fillet gel liquid preparations of A. vera to enhance the intestinal absorption and bioavailability of co-administered compounds as well as enhancement of skin permeation. In addition, important pharmaceutical applications such as the use of the dried A. vera gel powder as an excipient in sustained release pharmaceutical dosage forms will be outlined. PMID:18794775
Composition and Applications of Aloe vera Leaf Gel
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Josias H. Hamman
Full Text Available Many of the health benefits associated with Aloe vera have been attributed to the polysaccharides contained in the gel of the leaves. These biological activities include promotion of wound healing, antifungal activity, hypoglycemic or antidiabetic effects antiinflammatory, anticancer, immunomodulatory and gastroprotective properties. While the known biological activities of A. vera will be briefly discussed, it is the aim of this review to further highlight recently discovered effects and applications of the leaf gel. These effects include the potential of whole leaf or inner fillet gel liquid preparations of A. vera to enhance the intestinal absorption and bioavailability of co-administered compounds as well as enhancement of skin permeation. In addition, important pharmaceutical applications such as the use of the dried A. vera gel powder as an excipient in sustained release pharmaceutical dosage forms will be outlined.
Continuum Model of Heterogeneous Gels: Formation and Elastic Properties
Oshmian, V. G.; Benguigui, L.
A kinetic model of heterogeneous gel formation and a method to calculate gel stiffness are proposed, with application to the elastic properties of polyacrylamide gels. The model is based on assumptions about nucleation and growth of dense regions, governed by the concentration of monomer units (p_0) crosslink agent (c_0) and rate constants for chain propagation and curing. It is shown that at low c_0 the polymer and crosslink densities inside and outside an inclusion are almost the same and that the gel may be regarded as homogeneous. But the difference between densities increases sharply with c_0, giving growth of heterogeneities. Calculation of the elastic modulus was performed using a self-consistent method. Stiffness grows with p_0 at fixed c_0, but goes through a maximum as a function of c_0 at fixed p_0. The theoretical analysis is in qualitative agreement with the experimental data.
Gel-glass dispersed liquid crystal projection display
Levy, David; Quintana, Xabier; Rodrigo, Covadonga; Oton, Jose M.
Liquid crystal microdroplets trapped into silica gel glasses by sol-gel processes may be used for display applications. Gel-glass dispersed liquid crystals (GDLC) are switched between opaque and transparent states by applying external ac-voltage signals; no polarizers are required. Contrast ratio is enhanced in the projection mode as scattering from liquid crystal microdroplets is increased. Color emissive projection displays may be obtained by placing fluorescent RGB masks on the back plane; a UV lamp over the front plane excites the chromophors located under switched pixels, whereas unswitched pixels scatter the incoming UV light and the residual fluorescence. This setup takes advantage of the photostability of sol- gel glasses as compared to similar systems such as polymer-dispersed liquid crystals (PDLCs).
Resistivity and NMR of PMMA based gel electrolytes.
Czech Academy of Sciences Publication Activity Database
Krejza, O.; Sedla?íková, M.; Vondrák, Ji?í; Reiter, J.; Velická, Jana; Bartušek, K.
Banff : USEB, 2007, s. 5. ISBN N. [International Society of Electrochemistry /58./. Banff (CA), 09.09.2007-14.09.2007] Institutional research plan: CEZ:AV0Z40320502 Keywords : gel electrolytes Subject RIV: CA - Inorganic Chemistry
Investigations of rheological properties of diclofenac sodium gel preparation
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Firuza Maksudova
Full Text Available It is well-known that the majority of non-steroidal anti-inflammatory drugs (NSAIDs are ulcerogenic. Gel or ointment preparations of NSAIDs are free from this side-effect, which is a prerequisite for the increase of aforementioned forms of NSAIDs. A major quality indicator of gels and ointments are rheological properties. Along with determining the quality of preparation, they influence manufacturing, expiration date and terms of storage. This article demonstrates the results of investigation of rheological indices of 3% gel preparation of diclofenac sodium such as plasticity, structural viscosity, and thixotropy. Obtained results confirm that the developed gel preparation has thixotropy, plasticity and is classified as a Bingham system.
Measurement of body fluid proteins by polyacrylamide gel electrophoresis
Johnson, MH; Thompson, Ej
A development of the disc polyacrylamide gel electrophoretic system of Ornstein and Davis, which has been applied to the analysis of unconcentrated cerebrospinal fluid, is described. Modifications to the scanning densitometer have improved the signal:noise ratio of the gel scanning system. Using this technique, we have studied the dye-binding properties of albumin, and of beta- and gamma-globulins, and have shown that reproducible quantification of proteins can be achieved. The advantages of ...
Washing liquid effect on surimi gel rheological properties
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Vinnov Alexey Sergeevich
Full Text Available The purpose of this research was to compare the rheological properties of the modori and su-wari gels, obtained from minced carp washed with water and electro-activated by water systems. The results of comparative analysis of rheological properties of suwari and modori gels from minced carp, washed with tap water, catholyte and anolyte are presented. Effective viscosity in all cases is reversibly reduced with increasing shear rate and is stabilized for all considered soft gel samples at strain rate of 15–20 s-1. The effective viscosity maximum at small shear stress is ob-served for suwari from minced carp washed with catholyte with sodium chloride addition. This gel type is capable for effective viscosity intense reduction, under external mechanical effect. Under the sodium chloride influence, destruction intensity of gel structure for minced meat, washed with water, increases by 4,5 times, and for suwari from minced meat, washed by electroactivated sys-tems, this value is changing only by 1,4–0,73 times. The flow final segment analysis shows that the crystalline sodium chloride addition reduces the destruction intensity of suwari structure washed with water by 2, and with anolyte – by 4. The suvari and madory gels statistical critical shear stress values comparative research showed, that catholyte washed minced carp provide the largest values, taking into account moisture content in the product. The plastic flow of the soft gels from minced meat, washed by electro-activated systems begins at 1 700 Pa and it exceeds the yield strength of suwari washed with water almost twice. It is clear, that catholyte and anolyte application for obtaining washed carp minced meat provides obtaining suwari and modori gels with higher rheological properties than if it is washed with water.
Sol-gel nanocomposites as functional optical materials
Schmidt, Helmut K.
Small particle processing opens a variety of interesting aspects for optical applications. For the utilization, the sol-gel process offers a variety of routes, like colloid synthesis, incorporating into sol-gel derived matrices and in combination with photopolyermizabel components patterning processes based on photolithography. In this paper, a summary over a new conception of colloid stabilization and colloid processing by multifunctional ligands and further processing routes for optical app...
Optical materials by a modified sol-gel nanoparticle process
Schmidt, Helmut K.; Mennig, Martin
The use of sol-gel derived nanoparticles leads to interesting new materials and systems for optics. The basic principle, to combine transparent matrices with nanoparticles in sizes below remarkable scattering losses opens up new material technologies. The processing is almost as simple as sol-gel processing, and the use of polymerizable nanoparticle even leads to high performance coatings by using simple polymer techniques.
Chemical Sensors Based on Molecularly Imprinted Sol-Gel Materials
Franz L. Dickert; Lieberzeit, Peter A.; Adnan Mujahid
The sol-gel technique is earning the worldwide attention of researchers in the field of material science, due to its versatility in synthesizing inorganic ceramic materials at mild conditions. High purity, homogeneity, controlled porosity, stable temperature and nanoscale structuring are the most remarkable features offered by this method for generating highly sensitive and selective matrices to incorporate analyte molecules. The crafting of sol-gel sensors through molecular imprinting has pu...
Chemistry of material preparation by the sol-gel process
Schmidt, Helmut K.
A survey over the role of chemistry in sol-gel processing is given. The basic chemistry of the sol-gel process is complex due to the different reactivities of the network forming and the network modifying components and the wide variety of reaction parameters. Despite the important progress in the investigations of the mechanisms of hydrolysis and condensation, a direct relation of reaction parameters to material properties is still very difficult.
Development of Radiation Curable polymeric Gel Electrolyte Formulation
International Nuclear Information System (INIS)
The result of this study, the free lithium ions of polymer gel electrolyte containing hydroxyproply Cellulose 1% is the most excellent due to irradiate of strong energy over quick time, although curing reaction of EB system is a very fast, polymer gel electrolyte containing hydroxypropyl Cellulose Fabricated by UV system is excellent curing reaction and ionic conductivity and mechanical properties and thermal stability than EB system
Comparative Efficacy Of 2% And 1% Clotrimazole Gel In Dermatophytosis
Bandyopadhyay Debabrata
Fifty consecutive patients of dermatophytosis satisfying a set of inclusion/exclusion criteria randomly received treatment with either 1% or 2% clotrimazole gel in a double blind set up of 42 patients who completed the study. 20 received treatment with 1% (Gr. 1) and 22 with 2% (Gr. 2) clotrimazole gel. Trichophyton rubrum was grown in culture from lesions of all patients. No statistically significant difference was found in clinical scores and mycologic findings a...
Partition and permeation of dextran in polyacrylamide gel.
Williams, J.C.; Mark, L A; Eichholtz, S
Partition of sized FITC-dextrans in polyacrylamide gel showed a relationship between Kav and solute radius as predicted by the theory of Ogston, which is based solely on geometry of the spaces. Permeability data for the same dextrans were fit to several theories, including those based on geometry and those based on hydrodynamic interactions, and the gel structure predicted by the partition and permeability data were compared. The Brinkman effective-medium model (based on hydrodynamic interact...
Investigations of rheological properties of diclofenac sodium gel preparation
Firuza Maksudova; Ekut Karieva
It is well-known that the majority of non-steroidal anti-inflammatory drugs (NSAIDs) are ulcerogenic. Gel or ointment preparations of NSAIDs are free from this side-effect, which is a prerequisite for the increase of aforementioned forms of NSAIDs. A major quality indicator of gels and ointments are rheological properties. Along with determining the quality of preparation, they influence manufacturing, expiration date and terms of storage. This article demonstrates the results of investiga...
Rapid transfer of DNA from agarose gels to nylon membranes.
Reed, K C; Mann, D.A.
The unique properties of nylon membranes allow for dramatic improvement in the capillary transfer of DNA restriction fragments from agarose gels (Southern blotting). By using 0.4 M NaOH as the transfer solvent following a short pre-treatment of the gel in acid, DNA is depurinated during transfer. Fragments of all sizes are eluted and retained quantitatively by the membrane; furthermore, the alkaline solvent induces covalent fixation of DNA to the membrane. The saving in time and materials aff...
Deformation and fracture behavior of simulated particle gels
Rzepiela, A.A.
In this PhD project rheological properties of model particle gels are investigated using Brownian Dynamics (BD) simulations. Particle gels are systems of colloidal particles that form weakly bonded percolating networks interpenetrated by a suspending fluid. They are characterized as soft, deformable, elastic solids. Examples in the food domain are yogurt and cheese, in which the particles are casein micelles.Aggregation kinetics is discussed for a range of volume fractions. The model is set u...
Antifungal activity of aloe vera gel against plant pathogenic fungi
International Nuclear Information System (INIS)
Aloe vera gel extracted from the Aloe vera leaves was evaluated for their antifungal activity at the rate of 0.15%, 0.25% and 0.35% concentration against five plants pathogenic fungi viz., Aspergillus niger, Aspergillus flavus, Alternaria alternata, Drechslera hawaiensis and Penicillum digitatum 0.35% concentration Aloe vera gel completely inhibited the growth of Drechslera hawaiensis and Alternaria alternata. (author)
Gel del Vimang con actividad antifotoenvejecimiento: estudio histopatológico preliminar
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Angel R. Concepción
Full Text Available Se realizaron estudios de una nueva formulación (gel del Vimang, para evaluar en este caso parámetros histopatológicos, de un modelo in vivo; partiendo del antecedente que por resultados in vitro se sabe que el Vimang posee propiedades antioxidantes.Studies of a new formulation (Vimang's gel were conducted to evaluate, in this case, histopathological parameters of a model in vivo, starting from the antecedent that, according to results in vitro, Vimang has antioxidant properties.
Interaction between Covalent DNA Gels and a Cationic Surfactant
Costa, Diana; Hansson, Per; Schneider, Stefanie; Miguel, M. Grac?a; Lindman, Bjo?rn
The interaction of covalently cross-linked double-stranded (ds) DNA gels and cetyltrimethylammonium bromide (CTAB) is investigated. The volume transition of the gels that follows the absorption of the oppositely charged surfactant from aqueous solution is studied. As do other polyelectrolyte networks, DNA networks form complexes with oppositely charged surfactant micelles at surfactant concentrations far below the critical micelle concentration (cmc) of the polymer-free solution. The size of ...
Sol-Gel Materials with Pesticide Delivery Properties
Ligia Todan; Malina Raileanu; Maria Crisan; Ana Braileanu; Maria Zaharescu; Adrian Carpov; Corina Bradu; Adriana Rusu
Pesticides are widely used in agriculture, although they may create hazards both to humans and to the environment. In order to reduce the harmful effects of their administration, there has been made a great effort to find solutions. The porous sol-gel silica materials which are able to entrap different organic molecules represent new studied controlled release carriers. The aim of the present work was to prepare and characterize sol-gel composites based on trichlorfon as organophosphorous pes...
Silica Sol-Gel Coatings on Metals Produced by EPD
Castro, Y.; Ferrari, B.; Moreno, R.; Durán, A
The objective of this work has been to combine the sol-gel method and the electrophoretic deposition (EPD) process to prepare thick coatings onto metallic substrates. Two different routes were used for preparing the sol-gel silica suspensions. On one hand, silica particulate sols were obtained by basic catalysis of alkoxides and alkylalkoxides. On the other, silica suspensions were prepared by adding a commercial colloidal silica sol to an organic-inorganic acid catalysed silica s...
Synthesis of organically modified glasses by sol-gel techniques
Schmidt, Helmut K.
Sol-gel derived inorganic-organic composites can be prepared in homogeneities sufficient for optical applications. Therefore, it is necessary to control structure formation, especially with respect to the distribution or aggregation of inorganic network forming units and organics. Inorganic components can be kept on a nano level by growth control using stabilazors interacting with the surface of colloidal particles formed by sol-gel or precipitation reactions. Thus, colloidal particles < 10 n...
Sol-gel-based inorganic-organic composite materials
Schmidt, Helmut K.; Krug, Herbert
The sol-gel process allows the synthesis of inroganic non-metallic materials through a soft chemistry route and organic functions can be incorporated. While maintaining the phase size of the inorganic component on a molecular or nano range, inorganic molecular or nano composites can be fabricated. For this reason techniques that make use of surface interaction controlling ligands for colloidal sol-gel particles have been developed, allowing the inorganic part to be linked chemically to the or...
The Influence of Microgravity on Silica Sol-Gel Formation
Sibille, L.; Smith, D. D.; Cronise, R.; Hunt, A. J.; Wolfe, D. B.; Snow, L. A.; Oldenberg, S.; Halas, N.; Rose, M. Franklin (Technical Monitor)
We discuss space-flight experiments involving the growth of silica particles and gels. The effect of microgravity on the growth of silica particles via the sol-gel route is profound. In four different recipes spanning a large range of the parameter space that typically produces silica nanoparticles in unit-gravity, low-density gel structures were instead formed in microgravity. The particles that did form were generally smaller and more polydisperse than those grown on the ground. These observations suggest that microgravity reduces the particle growth rate, allowing unincorporated species to form aggregates and ultimately gel. Hence microgravity favors the formation of more rarefied structures, providing a bias towards diffusion-limited cluster-cluster aggregation. These results further suggest that in unit gravity, fluid flows and sedimentation can significantly perturb sol-gel substructures prior to gelation and these deleterious perturbations may be "frozen" into the resulting microstructure. Hence, sol-gel pores may be expected to be smaller, more uniform, and less rough when formed in microgravity.
Sol-gel Technology and Advanced Electrochemical Energy Storage Materials
Chu, Chung-tse; Zheng, Haixing
Advanced materials play an important role in the development of electrochemical energy devices such as batteries, fuel cells, and electrochemical capacitors. The sol-gel process is a versatile solution for use in the fabrication of ceramic materials with tailored stoichiometry, microstructure, and properties. This processing technique is particularly useful in producing porous materials with high surface area and low density, two of the most desirable characteristics for electrode materials. In addition,the porous surface of gels can be modified chemically to create tailored surface properties, and inorganic/organic micro-composites can be prepared for improved material performance device fabrication. Applications of several sol-gel derived electrode materials in different energy storage devices are illustrated in this paper. V2O5 gels are shown to be a promising cathode material for solid state lithium batteries. Carbon aerogels, amorphous RuO2 gels and sol-gel derived hafnium compounds have been studied as electrode materials for high energy density and high power density electrochemical capacitors.
Photopatterned free-standing polyacrylamide gels for microfluidic protein electrophoresis.
Duncombe, Todd A; Herr, Amy E
Designed for compatibility with slab-gel polyacrylamide gel electrophoresis (PAGE) reagents and instruments, we detail development of free-standing polyacrylamide gel (fsPAG) microstructures supporting electrophoretic performance rivalling that of microfluidic platforms. For the protein electrophoresis study described here, fsPAGE lanes are comprised of a sample reservoir and contiguous separation gel. No enclosed microfluidic channels are employed. The fsPAG devices (120 ?m tall) are directly photopatterned atop of and covalently attached to planar polymer or glass surfaces. Leveraging the fast up-scale from a unit separation to an array of 96 concurrent fsPAGE assays in 10 min run time driven by one electrode pair. The fsPAG array layout matches that of a 96-well plate to facilitate integration of the planar free standing gel array with multi-channel pipettes while remaining compatible with conventional slab-gel PAGE reagents, such as staining for label-free protein detection. Notably, the entire fsPAGE workflow from fabrication, to operation, and readout uses readily available materials and instruments - making this technique highly accessible. PMID:23609800
Piping and erosion phenomena in soft clay gels
International Nuclear Information System (INIS)
The present study has confirmed the conclusions from earlier investigations of piping and erosion of soft smectite gels by showing that the erodibility can be predicted by comparing the drag forces exerted by flowing water and the cohesive particle bonds in the gels. Optical microscopy used to identify the detailed erosion mechanisms shows that discrete flakes are not eroded as assumed earlier. The minerals torn off from the gels in fact consist of stable aggregates sized 5-50 ?m in the case of electrolyte-poor water and even larger units in ocean-type water. The theoretical model as well as the experiments show that erosion is initiated at a flow rate of 10-4 m/s in the first-mentioned type of water and that it becomes significant at 10-3m/s. In salt water the gels are much more erosion-resistant. Piping, which preceded the erosion in the tests, can take place in the form of radial expansion of natural pore passages in the gels, or by tensile failure, depending on the boundary conditions. Theoretically, the critical pressure to produce piping is about 1 kPa at water content of 1000% of Na montmorillonite and this appeared to be on the same order of magnitude as the experimentally determined values for the very conservative conditions that were applied. Separate tests of a clay rich in hydrous mica showed much less erodibility and higher piping resistance than of the smectite gels. (orig.)
Characterization of Hybrid Sol-gel Coatings Applied over Tinplate
Scientific Electronic Library Online (English)
D., Álvarez; A., Collazo; C., Pérez.
Full Text Available The present work studies the behavior of hybrid sol-gel films based on tetraethyl orthosilicate (TEOS) and vinyltrimethylsiloxane (VTMS) precursors applied over commercial tinplate. In previous works VTMS films obtained by the sol-gel technology were tested to verify their good corrosion performance [...] over short immersion times in a citric acid/sodium citrate buffer solution. However, at longer exposure times the high porosity inherent to organic sol-gel films allows the aggressive media to reach the metallic substrate and start the corrosion process. In order to overcome these limitations, hybrid organic-inorganic sol-gel coatings were obtained using the dip- coating method. This work also studies the influence of the ageing time of the hybrid sol-gel in the formation of a uniform and continuous film. The obtained layers were characterized using a Scanning Electron Microscopy (SEM) and mechanical profilometry. The corrosion performance in organic acid media was tested using polarization curves and Electrochemical Impedance Spectroscopy (EIS) with a 0.1M citric/citrate buffer solution as electrolyte. The results obtained suggest that a minimum ageing time of 10 days is needed to obtain uniform films. The electrochemical measurements indicate a clear improvement on the barrier properties on the hybrid sol-gel compared to the organic ones. A major decrease in the impedance values after 24 hours of immersion indicates that it is necessary to improve the long-term barrier properties to achieve an industrial application.
Stability of bentonite gels in crystalline rock
International Nuclear Information System (INIS)
The present, extended study comprises a derivation of a simple rock model as a basis for calculation of the penetration rate of bentonite and of the groundwater flow rate, which is a determinant of the erodibility of the protruding clay film. This model, which is representative of a gross permeability of about 10-8 - 10-9 m/s, implies a spectrum of slot-shaped joints with apertures ranging between 0.1 and 0.5 mm. It is concluded that less than 2percent of the highly compacted bentonite will be lost into traversing joints in 106 years. A closer analysis, in which also Poiseuille retardation and short-term experiments were taken into account, even suggests that the penetration into the considered joints will be less than that. The penetration rate is expected to be 1 decimeter in a few hundred years. The risk of erosion by flowing groundwater was estimated by comparing clay particle bond strength, evaluated from viscometer tests, and theoretically derived drag forces, the conclusion being that the maximum expected water flow rate in the widest joints of the rock model (4 times 10-4 m/s) is not sufficient to disrupt the gel front or the large individual clay flocs that may exist at this front. The experiments support the conclusion that erosion will not be a source of bentonite loss. A worst case scenario with a shear zone being developed across deposition holes is finally considered and in addition to this, the conditions in the fracture-rich tunnel floor at the upper end of the deposition holes are also analysed. This study shows that even if the rock is much more fractured than normal conditions would imply, the bentonite loss is expected to be very moderate and without substantial effect on the barrier functions of the remaining clay cores in the deposition holes. (author)
Two-dimensional Gel Electrophoresis (2DE)
K?odzi?ska, Ewa; Buszewski, Bogus?aw
The chemical compounds, which are present in the environment, increasingly cause bad effects on health. The most serious effects are tumors and various mutations at the cellular level. Such compounds, from the analytical point of view, can serve the function of biomarkers, constituting measurable changes in the organism's cells and biochemical processes occurring therein. The challenge of the twenty-first century is therefore searching for effective and reliable methods of identification of biomarkers as well as understanding bodily functions, which occur in living organisms at the molecular level. The irreplaceable tool for these examinations is proteomics, which includes both quality and quantity analysis of proteins composition, and also makes it possible to learn their functions and expressions. The success of proteomics examinations lies in the usage of innovative analytical techniques, such as electromigration technique, two-dimensional electrophoresis in polyacrylamide gel (2D PAGE), liquid chromatography, together with high resolution mass spectrometry and bio-informatical data analysis. Proteomics joins together a number of techniques used for analysis of hundreds or thousands of proteins. Its main task is not the examination of proteins inside the particular tissue but searching for the differences in the proteins' profile between bad and healthy tissues. These differences can tell us a lot regarding the cause of the sickness as well as its consequences. For instance, using the proteomics analysis it is possible to find relatively fast new biomarkers of tumor diseases, which in the future will be used for both screening and foreseeing the course of illness. In this chapter we focus on two-dimensional electrophoresis because as it seems, it may be of enormous importance when searching for biomarkers of cancer diseases.
A method for in-gel fluorescent visualization of proteins after native and sodium dodecyl sulfate polyacrylamide gel electrophoresis.
Pristov, Jelena Bogdanovi?; Opa?i?, Miloš; Dimitrijevi?, Milena; Babi?, Nikolina; Spasojevi?, Ivan
We have developed a simple one-step 30-min method for fluorescent visualization of proteins in native and sodium dodecyl sulfate polyacrylamide gel electrophoresis (PAGE) gels. The method is based on formation of strong fluorophores via potassium ferricyanide-provoked oxidation of tryptophan (Trp). Following PAGE, gels are soaked in water solution of potassium ferricyanide (100mM) and NaOH (1M) and are kept in the dark for 30min. Gels are then transferred to water and scanned. The sensitivity of the method was slightly lower compared with standard Coomassie Brilliant Blue (CBB) staining. The method can be useful when rapid acquisition of data is of the essence. After preview, gels can be post-stained using the CBB protocol for further analysis. The intensity of fluorescence is dependent on Trp number, so the protocol might find application in the quantification of Trp residues as illustrated here. Importantly, there is room for improvement of the method. Namely, according to excitation-emission matrix analysis of stained protein bands, maximal fluorescence intensity (at 345/460nm) was 3.5-fold higher compared with the settings that were available on a commercial imager (395/525nm). As a supplement, we present an upgrade of the previously described method for in-gel detection of non-heme iron-binding proteins that also employs potassium ferricyanide. PMID:25862081
Effect of drying methods on retention of moist sucralfate gel properties
Maggi, L.; Catellani, P. L.; Fisicaro, E.; Santi, P.; Zani, F.; Massimo, G.; Colombo, P.
The aim of this work was to find a drying procedure for moist sucralfate gel capable of producing dried sucralfate gel that retains the original gel properties of bioadhesion, rheology, and micromeritics. Spray-drying and microwave-drying procedures were employed. Mannitol was used as a gel-protective substance during the drying processes. The spray drying of moist sucralfate gel gave rise to a powder whose water suspensions showed significantly reduced viscosity. The bioadhesion of spray-dri...
sPP gel with high mechanical properties and high transparency by supercooling in mixed solvents
Takaesu, Keita; Hotta, Atsushi
Polymer gels are generally classified into chemical gels and physical gels depending on the types of crosslinking points. Physical gels are known to possess significantly poorer mechanical properties than chemical gels due to relatively weak crosslinking bonds in physical gels such as hydrogen bond and an intermolecular bond. In this work, physical sPP gels with extremely high mechanical properties and high transparency were successfully created by supercooling in mixed solvents. From our previous work, it was found that supercooling of physical gels (sPP/decalin gels) could produce gels with high mechanical properties comparable to chemical gels but maintaining the advantages of physical gels such as stimulus-responsiveness and reversibility, which cannot be realized by using chemical gels. Here, we also used tetrahydronaphthalene (tetralin) as solvent. The mechanical properties of sPP/tetralin were degraded by supercooling but intriguingly enhancement in the mechanical properties of sPP gels could be observed by using mixed solvent of decalin and tetralin, which eventually showed twice as high fracture stress as sPP/decalin gels.
Directory of Open Access Journals (Sweden)
Amruta B. Kumbhar*, Ashwini K. Rakde, P.D. Chaudhari
Full Text Available Recently, controlled and sustained drug delivery has become the standard in modern pharmaceutical design and an intensive research have been undertaken in achieving much better drug product effectiveness, reliability and safety. This interest has been sparked by the advantages shown by in situ gel forming drug delivery systems such as ease of administration and reduced frequency of administration, improved patient compliance and comfort. The formation of gels depends on factors like temperature modulation, pH change, presence of ions and ultra violet irradiation, from which the drug gets released in a sustained and controlled manner. Various biodegradable polymers that are used for the formulation of in situ gels include gellan gum, alginic acid, xyloglucan, pectin, chitosan, poly(DL lactic acid, poly(DL-lactide-co-glycolide and poly-caprolactone. Mainly in situ gels are administered by oral, ocular, rectal, vaginal, injectable and intraperitoneal routes. In situ gel forming injectable drug delivery system is the ability to inject a drug incorporated into a polymer to a localized site and have the polymer form a semi-solid gel drug depot has a number of advantages. Among these advantages is ease of application and localized, prolonged drug delivery. Biodegradable injectable in situ gel forming drug delivery systems represent an attractive alternative to microspheres, liposomes and emulsion as parenteral depot systems. For these reasons a large number of in situ gelling polymeric delivery systems have been developed and investigated for use in delivering a wide variety of drugs. The various strategies that have been used to prepare in situ gelling systems and outline their advantages and disadvantages as localized drug delivery systems. From a manufacturing point of view, the production of such devices is less complex and thus lowers the investment and manufacturing cost.
Modelling the behaviour of the push-pull gel dosimeter
International Nuclear Information System (INIS)
Full text: Recent development of a gel dosimeter based on the radiobleaching pigment, genipin, allows development of a new 3D optically scanned gel dosimeter-the push-pullgel. This gel would contain two spectrally complementary pigments, one which darkens with dose and another (e.g. genipin) which bleaches. The two pigments deal separately with the high and low dose ends of the dosimeter's dynamic range. The bleaching pigment would be optimised for high sensitivity and the darkening pigment for low. Employing dual pigments, optimised independently, relaxes the need for compromise between sensitivity at low dose and accuracy at high dose. Such a gel, after exposure, would be read using two successive optical CT scans, at two different wavelengths. The reduction in sensitivity of the darkening pigment (allowed by the use of push-pull) would reduce the occurrence of regions of high optical attenuation which can generate optical CT artefacts. Simulated optical CT reconstructions of the optical density map (Fig. La) scanned at the darkening pigment wavelength of a hypothetical push-pull gel, confirms the reduction in susceptibility to artefacts. Fig. I b shows a profile through the map with no stray light added. The centre of the profile in Fig. I d shows a cupping artefact produced by 10 ppm of stray light. The similarity of Fig. Ic and b show that a 30% sensitivity reduction allowed by push-pull, renders the artefact negligible. This paperenders the artefact negligible. This paper presents the results of' these simulations of a push-pull gel scanned using optical CT and also some results of experiments with genipin gel. (author)
Gel Generator Technology Viability for Small Scale Production - Indian Experience [Country report: India - GEL Gen.
International Nuclear Information System (INIS)
The radioisotope 99mTc is used in nearly 80% of all diagnostic imaging procedures in nuclear medicine and hence ensuring its uninterrupted availability is of prime importance to the nuclear medicine industry. Of the various options available for accessing 99mTc from its precursor 99Mo through a generator system, the 99mTc generator using a bed of acidic alumina column for column chromatographic separation of 99mTc from 99Mo remains the most popular procedure world over. The uninterrupted availability of high specific activity (n,f)99Mo, an essential requirement for the alumina column generators and produced by few large scale commercial suppliers, needs to be ensured to avoid frequent disruption in 99mTc supplies. Alternate technologies that could use (n,?)99Mo to meet partial/complete domestic demands are worth exploring to reduce import dependency/foster self-sufficiency particularly in countries having the necessary infrastructure in place. The Indian pursuit of gel generator technology for 99mTc was driven mainly by three considerations, namely, (i) reliable, well-established and ease of production of (n,?)99Mo in TBq quantities in the research reactors in Trombay/Mumbai, India, (ii) need for relatively low-cost alternate technology to replace the solvent (MEK) extraction generator system in use in India since 1970s and (iii) minimize dependency on weekly import of fission-produced 99Mo raw material required for alumina column generator. The development of column type 99mTc generator based on conversion of (n,?)99Mo as zirconium molybdate-99Mo (ZrM) gel matrix and subsequent separation of 99mTc by elution in normal saline was an important development in this direction, as this combines the advantages of using (n,?)99Mo and a column based separation technique. A considerable volume of work was carried out at the Board of Radiation and Isotope Technology (BRIT) both independently and as a part of IAEA's CRP [4,9] for standardization of the process. After successful completion of feasibility studies and small scale production and supply of gel generators to local hospitals, development of technology for regular production and supply was undertaken. A multidisciplinary core team comprising of chemists and engineers working in close collaboration enabled successful completion of the project. The technology development entailed four major aspects: (i) adaptation of chemical process to automation, (ii) design and erection of a production facility with adequate shielding, (iii) design/fabrication/installation of operation specific gadgets, and (iv) design of a compact, portable, easy to assemble and reusable generator assembly. The production facility, having a capacity to produce up to 25 generators per batch in an 8 hour shift operation, has been operational since the past five years. We report here the salient aspects of technology development and operational experience of producing the gel generators thereby demonstrating the viability of the technology
Gel dosimetry - a laser based 3D scanner for gel samples - research in India
Energy Technology Data Exchange (ETDEWEB)
Widmer, Johannes [Institut fuer Angewandte Photophysik, TU Dresden (Germany); Photonics Division, VIT University, Vellore, Tamil Nadu (India); Dhiviyaraj Kalaiselven, Senthil Kumar [Photonics Division, VIT University, Vellore, Tamil Nadu (India); Department of Therapeutic Radiology, University of Minnesota, Minneapolis (United States); James, Jebaseelan Samuel [Photonics Division, VIT University, Vellore, Tamil Nadu (India)
A laser based 3D scanner is developed to take tomography images of partly transparent samples. The scanner is optimized to characterize gel samples from spatially resolved dosimetry measurements. The resulting device should be suitably designed to be constructed in India. This gave me valuable insight into the scientific and technological environment of the country and made me find my way through a quite different culture of research and commerce, within and beyond the scientific context of the university. The project was implemented during a nine months stay at the Vellore Institute of Technology University in Vellore, Tamil Nadu, India, in co-operation with the Christian Medical College, Vellore, in 2006/07. It was conducted within the framework of existing research activities of the host university.
Gel dosimetry - a laser based 3D scanner for gel samples - research in India
International Nuclear Information System (INIS)
A laser based 3D scanner is developed to take tomography images of partly transparent samples. The scanner is optimized to characterize gel samples from spatially resolved dosimetry measurements. The resulting device should be suitably designed to be constructed in India. This gave me valuable insight into the scientific and technological environment of the country and made me find my way through a quite different culture of research and commerce, within and beyond the scientific context of the university. The project was implemented during a nine months stay at the Vellore Institute of Technology University in Vellore, Tamil Nadu, India, in co-operation with the Christian Medical College, Vellore, in 2006/07. It was conducted within the framework of existing research activities of the host university.
BANG polymer gels applied to heavy carbon ion dosimetry
International Nuclear Information System (INIS)
Full text: BANGTM polymer-gel and magnetic resonance imaging (MRI) can be used to measure dose distributions produced by conformal carbon ion radiotherapy. Radiation induced local changes in the molecular structure of the polymer affect the water proton MR longitudinal and transverse relaxation times T1 and T2. The changes are large enough to be mapped with high spatial resolution. In analogy to the radiobiological efficiency of high LET radiation the dose response of polymer-gels relative to photon radiation were investigated systematically. BANGTM polymer-gel phantoms were irradiated with monoenergetic 12C ion beams in the energy range between EP = 100 and 400 MeV/u. To avoid deviations from the linearity of dose response particle fluences were restricted to an expected maximum dose in the bragg peak of 10Gy. For dose calibration and efficiency calculation the gels were irradiated with sparsely ionising 6MV photon radiation. The MR images were measured with a 1.5T whole body scanner (Magnetom, Siemens) using a head coil. The transverse MR relaxation rate R2=1/T2 of the water protons was taken as a measure of the radiation dose absorbed in the gels, calculated from series of multi spin echo sequences (TR = 3s, TE = 20-640 ms, ?TE = 20 ms). As far as quality is concerned, there is good agreement between measured and planned dose distributions. Quantitatively, significant differencns. Quantitatively, significant differences are found when comparing the measured amplitude and the planned physical dose profiles. The observations are caused by saturation effects of the densely ionising carbon beam penetrating matter. The examination yielded first effectiveness values of carbon ion irradiation which are depending on the linear energy transfer (LET). With decreasing LET, i.e. increasing projectile energy the dose response and the efficiency of the BANGTM gel increases. Since fragmentation of the primary beam along its path results in a mixed radiation field, measurements need to be extended to light ion data. BANGTM gel dosimetry is applied to conformal carbon ion irradiation. Dose contours and gradients can be imaged in three dimensions with high spatial resolution. At present, the dependence of the BANGTM gel efficiency on heavy ion energy does not allow an absolute dose measurement. However, once this dependence is known with sufficient accuracy, MR imaging of tissue-equivalent aqueous BANGTM polymer-gel will become a convenient method for the verification of three-dimensional dose distributions in carbon-ion radiotherapy. Copyright (2000) Australasian College of Physical Scientists and Engineers in Medicine
Polymer gels for in-phantom dose imaging in radiotherapy
International Nuclear Information System (INIS)
Full text: In recent radiotherapy techniques, aimed at achieving high dose release in volumes conformal to the tumours and low dose in the surrounding healthy tissue, the high nonuniformity of the dose spatial distribution makes imperative to perform reliable 3-D determinations. In last years, a growing up interest was focussed on gel dosimetry. The method is based on the analysis of a tissue-equivalent gel medium that acts by itself as continuous dosimeter. Such a dosimetric matrix is obtained by incorporating a chemical dosimeter into a tissue-equivalent gel. The first studied gel-dosimeters were gel phantoms containing a Fricke solution, that can be mainly considered as a ferrous sulphate solution. After exposure to ionising radiation, chemical reactions give rise to oxidation of ferrous ions Fe2+ into ferric ions Fe3+ with ferric ion yield proportional to the absorbed dose. Owing to the diffusion of ferric ions in the gel matrix, with the consequent necessity of performing the analysis within a short time after irradiation, new kind of gel dosimeters, called polymer gels dosimeters (PGD), are under study. The purpose is to obtain dosimeters showing changes correlated to the absorbed dose that do not involve diffusive ions. PGD are based on gel matrices in which radiation induces a polymerisation process that increases the opacity of the medium allowing optical imaging. In this study, PGD of different shape were exposed to photon fields, at vashape were exposed to photon fields, at various energies and light transmittance was measured by means of a spectrophotometer or a CCD camera. Many characteristics of the PGDs were investigated: i) reproducibility and linearity of the PGD relative dose response varying the delivered dose; ii) reproducibility and linearity of the PGD relative dose response varying the time between irradiation and analysis; iii) reliability of the absolute depth dose profiles and superficial absolute dose measurements, which were compared to ionization chamber readings and Monte Carlo (Penelope) calculations. The polymer dosimeters have show promising characteristics and deserve further studies
Three-dimensional gel dosimetry for carbon ion beam radiotherapy
International Nuclear Information System (INIS)
To meet the requirements for three dimensional (3D) dose verification of precise radiotherapy, methacrylic acid gel 3D dosimetry was developed. However, this dosimeter still has some problems for clinical use. The aim of this study is to investigate the efficacy of methacrylic acid gel 3D dosimetry for carbon ion beams. Beakers filled with methacrylic acid gel whose components were 16% gelatin by weight (260 bloom), ascorbic acid, CuSO4·5H2O, hydroquinone, 5% methacrylic acid by weight and distilled water were employed. They are irradiated with 12C of 290 MeV/u external beam. Magnetic resonance (MR) imagings of the irradiated beakers were performed to obtain the T2 value maps. From the data of T2 value maps, the transverse water relaxation rates (R2=1/T2 value) were calculated. The relative water equivalent thickness of the methacrylic acid gel (Tg/Tw) was measured using an ion chamber. The R2 and irradiation doses were linearly correlated between 0 Gy and 10 Gy (correlation coefficient = 0.995). Tg/Tw was 1.04. The use of the methacrylic acid gel 3D dosimetry, in combination with MRI, seems to promise for dosimetric verification in the carbon ion beam radiotherapy. (author)
Gas control treatment with gel in Varadero field
Energy Technology Data Exchange (ETDEWEB)
Archer, F.; Reyna, M.; Rauseo, O. [PDVSA Petroleos de Venezuela SA, Caracas (Venezuela, Bolivarian Republic of). INTEVEP; Tavares, D. [CUPET, Havana (Cuba)
Located in Cuba's Matanzas province, the Varadero oil field contains significant oil and gas resources. However, stringent environmental regulations have caused the closure of wells due to the high content of hydrogen sulphide (H{sub 2}S) released into the environment during gas production activities. This paper discussed the use of a polymer gel designed to control gas. The effect of the disproportionate reduction of permeability (DPR) in the sealant was investigated at high temperatures for use in carbonate deposits. A batch injection technique was used to seal gas-producing fractures and control excess gas production in the fractured reservoir. Laboratory tests were conducted to determine formulations and gel volume requirements. The gel was then applied to a test well with a shut-in time of 7 days in order to ensure maximum gel consistency. It was concluded that gel application is a successful method for controlling excess gas production in fractured carbonate reservoirs. Increased oil production may be attributed to lower gas flow rates. It was concluded that further studies are needed in order to determine duration of the treatment and its economic viability. 4 refs., 1 tab., 1 fig.
Preparation of silica by sol-gel method using formamide
Scientific Electronic Library Online (English)
R.F.S., Lenza; W.L., Vasconcelos.
Full Text Available In this work we obtained microporous and mesoporous silica gels by sol-gel processing. Tetraethylortosilicate (TEOS) was used as precursor. Nitric acid and hydrofluoric acid were used as catalysts. In order to study the affect of formamide as drying additive, we used a molar ratio alkoxide/formamide [...] of 1/1. The performance of formamide in obtaining crack-free gels was evaluated through monolithicity measurements. The structural evolution occurring in the interconnected network of the gels during thermal treatment was monitored by Fourier transform infrared spectroscopy (FTIR), shrinkage and density measurements and nitrogen gas sorption. We noted that in the presence of formamide, the Si-O-Si bonds are stronger and belong to a more cross-linked structure. The samples obtained in the presence of formamide have larger pore volume and its pore structure is in the range of mesoporosity. The samples obtained without additive are microporous. Formamide allowed the preparation of crack-free silica gels stabilized at high temperatures.
Removal of DNA curving by DNA ligands: gel electrophoresis study.
Barcelo, F; Muzard, G; Mendoza, R; Révet, B; Roques, B P; Le Pecq, J B
The removal of inherent curving in Crithidia fasciculata kinetoplast DNA by various small DNA ligands, groove binders and mono- and bisintercalators, has been studied by gel retardation and electron microscopy. The migration of the kinetoplast DNA fragment is highly retarded during gel electrophoresis. We demonstrate that this retardation is suppressed by DNA ligands such as distamycin and ditercalinium, which have different modes of binding and sequence specificities. Observation by electron microscopy confirms that the effect of ditercalinium on gel migration of curved DNA is linked to DNA uncurving. As the drug is progressively added to DNA, a large broadening of the retarded band is observed during gel electrophoresis for distamycin and ditercalinium. In the case of distamycin, the retarded DNA band splits into two broad bands, whereas the noncurved DNA bands remain homogeneous. This indicates that the drug-DNA exchange is extremely slow in the gel and that a limited number of specific sites on DNA are critical for the removal of bending. GC-specific quinomycin, monointercalators, and bisintercalators act in a manner similar to that of AT-specific distamycin. This indicates that direct drug binding at the dAn tracts is not required for DNA uncurving. We propose that the uncurving of kinetoplast DNA by drugs is caused by a global alteration of DNA structure; subsequent increased flexibility leads to the suppression of rigid bending at the AT tract junctions. PMID:1645181
Structural Evolution and Stability of Sol-Gel Biocatalysts
International Nuclear Information System (INIS)
Full text: Immobilisation strategies for catalytic enzymes are important as they allow reuse of the biocatalysts. Sol-gel materials have been used to immobilise Candida antarctica lipase B (CALB), a commonly used industrial enzyme with a known crystal structure. The sol-gel bioencapsulate is produced through the condensation of suitable metal alkoxides in the presence of CALB, yielding materials with controlled pore sizes, volume and surface chemistry. Sol-gel matrices have been shown to prolong the catalytic life and enhance the activity of CALB, although the molecular basis for this effect has yet to be elucidated due to the limitations of analysis techniques applied to date. Small angle neutron scattering (SANS) allows such multicomponent systems to be characterised through contrast matching. In the sol-gel bioencapsulate system, at the contrast match point for silica, residual scattering intensity is due to the CALB and density fluctuations in the matrix. A SANS contrast variation series found the match point for the silica matrix, both with and without enzyme present, to be around 35 percent. The model presented here proposes a mechanism for the interaction between CALB and the surrounding sol-gel matrix, and the observed improvement in enzyme activity and matrix strength. The SANS protocol developed here may be applied more generally to bioencapsulates. (authors)
Preparation of silica by sol-gel method using formamide
Directory of Open Access Journals (Sweden)
R.F.S. Lenza
Full Text Available In this work we obtained microporous and mesoporous silica gels by sol-gel processing. Tetraethylortosilicate (TEOS was used as precursor. Nitric acid and hydrofluoric acid were used as catalysts. In order to study the affect of formamide as drying additive, we used a molar ratio alkoxide/formamide of 1/1. The performance of formamide in obtaining crack-free gels was evaluated through monolithicity measurements. The structural evolution occurring in the interconnected network of the gels during thermal treatment was monitored by Fourier transform infrared spectroscopy (FTIR, shrinkage and density measurements and nitrogen gas sorption. We noted that in the presence of formamide, the Si-O-Si bonds are stronger and belong to a more cross-linked structure. The samples obtained in the presence of formamide have larger pore volume and its pore structure is in the range of mesoporosity. The samples obtained without additive are microporous. Formamide allowed the preparation of crack-free silica gels stabilized at high temperatures.
Gel electrode imaging of fatigue cracks in titanium
International Nuclear Information System (INIS)
In a recent series of reports, a new and simple technique was introduced which detects and images fatigue damage in aluminum alloys with an electrochemical gel electrode. This new technique is based upon two factors: (i) the creation of microcracks in a surface anodic oxide film during fatigue of the underlying metal, and (ii) the detection of these microcracks by contacting the surface with a gel electrolyte containing KI and starch, and applying a voltage pulse to stimulate corrosion currents. These currents flow preferentially through the microcracks in the oxide film and release iodine ions which react with the starch to form a black complex in the surface of the gel. In this way an image is formed of the sites of current flow. The initial experiments on aluminum alloys demonstrated that the gel electrode is very sensitive: fatigue cracks as short as 10 ?m in length were detected, while fatigue deformation was detected and measured earlier than 1% of the fatigue life. This report demonstrates that the technique offers a similar sensitivity for the detection and imaging of fatigue cracks in titanium. Gel electrode images are compared with scanning electron micrographs of the specimen itself to show that cracks greater than or equal to 20 ?m long are detectable
Morphology and Rheological Behaviour of Ag-SBS Nanocomposite Gels
Peponi, Laura; Torre, Luigi; Kenny, Josč M.; Mondragon, Ińaki
Block copolymers are of both theoretical and practical importance because of their ability to self-assemble in nano-ordered structures. The self-assembly processes in these materials, are a consequence of the intermolecular micro phase separation between the dissimilar chains covalently linked together. Another important property of block copolymers is that, in solution with a selective solvent, they aggregate to form physical gels. Their technological importance is due to their ability to form elastic solids via self-assembly, with midblocks bridging aggregated end-block micelles. In our study poly(styrene-b-butadiene-b-styrene) (SBS), form, by its dissolution in a mid-block-selective solvent (THF) physical gels. So the morphology and the rheological behavior of the thermoreversible gels have been studied and characterized. Moreover, the gel behavior was also studied when Ag nanoparticles were added to the SBS matrix. The results of this study show that the gel stability is not affected by the presence of Ag nanoparticles.
Nanoparticle solutions as adhesives for gels and biological tissues
Rose, Séverine; Prevoteau, Alexandre; Elzičre, Paul; Hourdet, Dominique; Marcellan, Alba; Leibler, Ludwik
Adhesives are made of polymers because, unlike other materials, polymers ensure good contact between surfaces by covering asperities, and retard the fracture of adhesive joints by dissipating energy under stress. But using polymers to `glue' together polymer gels is difficult, requiring chemical reactions, heating, pH changes, ultraviolet irradiation or an electric field. Here we show that strong, rapid adhesion between two hydrogels can be achieved at room temperature by spreading a droplet of a nanoparticle solution on one gel's surface and then bringing the other gel into contact with it. The method relies on the nanoparticles' ability to adsorb onto polymer gels and to act as connectors between polymer chains, and on the ability of polymer chains to reorganize and dissipate energy under stress when adsorbed onto nanoparticles. We demonstrate this approach by pressing together pieces of hydrogels, for approximately 30 seconds, that have the same or different chemical properties or rigidities, using various solutions of silica nanoparticles, to achieve a strong bond. Furthermore, we show that carbon nanotubes and cellulose nanocrystals that do not bond hydrogels together become adhesive when their surface chemistry is modified. To illustrate the promise of the method for biological tissues, we also glued together two cut pieces of calf's liver using a solution of silica nanoparticles. As a rapid, simple and efficient way to assemble gels or tissues, this method is desirable for many emerging technological and medical applications such as microfluidics, actuation, tissue engineering and surgery.
Performance Evaluation and Experimental Studies on Metallised Gel Propellants
Directory of Open Access Journals (Sweden)
T. L. Varghese
Full Text Available Metallised gel propellants offer higher specific impulse and volumetric loading, reduced vaporisation loss, spillage and slosh problems and easy storage in comparison to the conventional liquid propellants. Theoretical performance analysis of gel propellant containing Al in unsymmetrical dimethyl hydrazine-dinitrogen tetroxide (UDMH-N/sub 2/O/sub 4} system shows peak Isp (vacuum condition of 316.7 s and 318.3 s at oxidiser/fuel (O/f ratios of 1.5 and 1.0, respectively for 30 per cent and 40 per cent UDMH-Al gel propellants, under standard conditions. The effect of other parameters like area ratio and chamber pressure on performance has been brought out in view of mission oriented applications. Aluminium has been found to be a better choice over magnesium in metallised gel propellants. Experimental studies on UDMH gellation using propellant grade (15 micrometerand pyrotechnic grade (1.5 micrometerAl in 500g batch level show that gellant(methyl cellulose concentration could be reduced by 50 percent using pyrotechnic grade Al. The pseudoplastic-thixotropic behaviour, flow rate through die holes, burst pressure tests and bulk density are studied. UDMH -25 to 30 per cent Al gels with both grades of Al are found to be stable, pseudoplastic (shear thinning and thixotropic (time-dependent shear thinning, but their flow pattern through die holes differ in nature.
Development and Characterization of NMR Measurements for Polymer Gel Dosimetry
Kwong, Zachary; Whitney, Heather
Polymer gel dosimeters are systems of water, gelatin, and monomers which form polymers upon irradiation. The gelatin matrix retains dose distribution in 3D form, facilitating truly integrated measurements of complex dose plans for radiation therapy. Polymer gels have two proton pools coupled by exchange: free solvent protons and bound polymerized macromolecular protons. Measuring magnetization transfer (MT) and relaxation affords useful insights into particle rigidity and chemical exchange effects on relaxation in polymer gels. Polymer gel dose response has been previously quantified with several techniques, most often in terms of MRI parameters, usually at field strengths of 1.5 T and below. The research described here investigates the dose response of a revised MAGIC gel dosimeter via both high-field imaging and simpler nuclear magnetic resonance (NMR) spectroscopy. This includes both transverse and longitudinal relaxation rates (R2 and R1) and quantitative MT parameters. We investigated estimating polymer molecular weight for a given applied dose using the Rouse model and R2 data from the imaging study. Finally, we began development of NMR methods for studying dose response, requiring adaption of NMR experiments to accommodate for radiation damping.
2D gels still have a niche in proteomics
DEFF Research Database (Denmark)
Rogowska-Wrzesinska, Adelina; Le Bihan, Marie-Catherine
With the rapid advance of MS-based proteomics one might think that 2D gel-based proteomics is dead. This is far from the truth. Current research has shown that there are still a number of places in the field of protein and molecular biology where 2D gels still play a leading role. The aim of this review is to highlight some of these applications. Examples from our own research as well as from other published works are used to illustrate the 2D gel driven research in the areas of: 1) de novo sequencing and protein identification from organisms with no or incomplete genome sequences available; 2) alternative detection methods for modification specific proteomics; 3) identification of protein isoforms and modified proteins. With an example of the glycoprotein TIMP-1 protein we illustrate the unique properties of 2D gels for the separation and characterisation of multiply modified proteins. We also show that careful analysis of experimental and theoretical protein mass and pI can lead to the identification of unanticipated protein variants modified by for example proteolytic cleavage. Together this shows that there is an important niche for 2D gel-based proteomics, which compliments traditional LC-MS techniques for specific protein research purposes. This article is part of a Special Issue entitled: EUPA 2012: NEW HORIZONS.
New insights into uranium (VI) sol-gel processing
International Nuclear Information System (INIS)
Nuclear Magnetic Resonance (NMR) investigations on the Oak Ridge National Laboratory process for sol-gel synthesis of microspherical nuclear fuel (UO2), has been extremely useful in sorting out the chemical mechanism in the sol-gel steps. 13C, 15N, and 1H NMR studies on the HMTA gelation agent (Hexamethylene tetramine, C6H12N4) has revealed near quantitative stability of this adamantane-like compound in the sol-gel process, contrary to its historical role as an ammonia source for gelation from the worldwide technical literature. 17O NMR of uranyl (UO2++) hydrolysis fragments produced in colloidal sols has revealed the selective formation of a uranyl trimer, [(UO2)3(?3-O)(?2-OH)3]+, induced by basic hydrolysis with the HMTA gelation agent. Spectroscopic results will be presented to illustrate that trimer condensation occurs during sol-gel processing leading to layered polyanionic hydrous uranium oxides in which HMTAH+ is occluded as an ''intercalation'' cation. Subsequent sol-gel processing of microspheres by ammonia washing results in in-situ exchange and formation of a layered hydrous ammonium uranate with a proposed structural formula of (NH4)2 [(UO2)8 O4 (OH)10] · 8H2O. This compound is the precursor to sintered UO2 ceramic fuel. 23 refs., 10 figs
Allopurinol gel mitigates radiation-induced mucositis and dermatitis
International Nuclear Information System (INIS)
It has not been verified whether allopurinol application is beneficial in decreasing the severity of radiation-induced oral mucositis and dermatitis. Rats were divided into 4 groups and received 15 Gy irradiation on the left whisker pad. Group 1 received only irradiation. Group 2 was maintained by applying allopurinol/carrageenan-mixed gel (allopurinol gel) continuously from 2 days before to 20 days after irradiation. Group 3 had allopurinol gel applied for 20 days after radiation. Group 4 was maintained by applying carrageenan gel continuously from 2 days before to 20 days after irradiation. The intra oral mucosal and acute skin reactions were assessed daily using mucositis and skin score systems. The escape thresholds for mechanical stimulation to the left whisker pad were measured daily. In addition, the irradiated tissues at the endpoint of this study were compared with naive tissue. Escape threshold in group 2 was significantly higher than that in group 1, and mucositis and skin scores were much improved compared with those of group 1. Concerning escape threshold, mucositis and skin scores in group 3 began to improve 10 days after irradiation. Group 4 showed severe symptoms of mucositis and dermatitis to the same extent as that observed in group 1. In the histopathological study, the tissues of group 1 showed severe inflammatory reactions, compared with those of group 2. These results suggest that allopurinol gel application can mitigate inflammation reactions asion can mitigate inflammation reactions associated with radiation-induced oral mucositis and dermatitis. (author)
Study of density and stability of a lung-equivalent gel
Claeys, Carolien; de Deene, Yves; Truyens, Bart; de Wagter, Carlos
Gel dosimetry is a useful tool for the verification of radiation treatments in water-equivalent tissues. In order to extend the application of gel dosimetry to the lung, the density of the dosimeter should be reduced. Some methods have been proposed for the fabrication of low-density gels. Major challenges in the fabrication of these gel dosimeters are to achieve a density that equals the electron-density of lung tissue and to obtain an acceptable homogeneity. Both polymer and Fricke gel formulations have been used as basic chemical compositions for low-density gel dosimeters. To reduce the density, two approaches have been suggested: (1) Styrofoam beads can be added to the gel or (2) the gel can be beaten until a foam is obtained. In this study we followed the latter method and added sodium-dodecyl-sulphate (SDS) as a surfactant to increase the surface tension of the gel.
Fluid diversion and sweep improvement with chemical gels in oil recovery processes
Energy Technology Data Exchange (ETDEWEB)
Seright, F.S.; Martin, F.D.
The objectives of this project are to identify the mechanisms by which gel treatments divert fluids in reservoirs and to establish where and how gel treatments are best applied. Several different types of gelants are being examined. This research is directed at gel applications in water injection wells, in production wells, and in high-pressure gas floods. The work will establish how the flow properties of gels and gelling agents are influenced by permeability, lithology, and wettability. Other goals include determining the proper placement of gelants, the stability of in-place gels, and the types of gels required for the various oil recovery processes and for different scales of reservoir heterogeneity. This report describes progress made during the first year of this three-year study the following tasks: gel screening studies; impact of gelation pH, rock permeability, and lithology on the performance of a monomer-based gel; preliminary study of the permeability reduction for CO{sub 2} and water using a resorcinol-formaldehyde gel; preliminary study of permeability reduction for oil and water using a resorcinol-formaldehyde gel; rheology of Cr(III)-xanthan gel and gelants in porous media; impact of diffusion, dispersion, and viscous fingering on gel placement in injection wells; examination of flow-profile changes for field applications of gel treatments in injection wells; and placement of gels in production wells. Papers have been indexed separately for inclusion on the data base.
Swelling-induced and controlled curving in layered gel beams.
Lucantonio, A; Nardinocchi, P; Pezzulla, M
We describe swelling-driven curving in originally straight and non-homogeneous beams. We present and verify a structural model of swollen beams, based on a new point of view adopted to describe swelling-induced deformation processes in bilayered gel beams, that is based on the split of the swelling-induced deformation of the beam at equilibrium into two components, both depending on the elastic properties of the gel. The method allows us to: (i) determine beam stretching and curving, once assigned the characteristics of the solvent bath and of the non-homogeneous beam, and (ii) estimate the characteristics of non-homogeneous flat gel beams in such a way as to obtain, under free-swelling conditions, three-dimensional shapes. The study was pursued by means of analytical, semi-analytical and numerical tools; excellent agreement of the outcomes of the different techniques was found, thus confirming the strength of the method. PMID:25383031
Charge transport in ion-gel gated IDTBT transistors
Wang, Shun; Bao, Bei; Shao, Xianyi; Tan, Lu; Wu, Yueshen; Wen, Libin; Bai, Xuxu; Guo, Xiaojun; Liu, Ying
Ionic liquids (ion gels) have been employed as the gate dielectric for polymer transistors due to its ultra-high capacitance. At high charge carrier density provided by ionic liquid gating, polymers like P3HT and PBTTT can exhibit very high mobility. We have fabricated ion-gel gated IDTBT transistors and measured its charge transport properties. We found that the mobility of ion-gel gated IDTBT transistors is greatly suppressed compared to the Cytop gated devices. At carrier density on the order of 1021/cm3, IDTBT shows mobility of about 0.05 cm2/V/s. Detailed analysis of the temperature dependence of resistivity shows 3D Mott variable range hopping in IDTBT at such carrier density, indicating a different charge transport mechanism from Cytop gated device.
Preparation and evaluation of gels from gum of Moringa oleifera
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Panda D
Full Text Available The present study was undertaken with an objective to find out the gelling potentials of a natural gum obtained from plant Moringa oleifera . The gum was extracted by using water as solvent and precipitated using acetone as non-solvent. Physical characteristics such as, solubility, swelling index, loss on drying, and pH were studied. Diclofenac sodium was used as model drug for the formulation of gels. Seven batches of drug loaded gels with concentration of mucilage ranging from 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, and 8.5 were formulated by using glycerin as plasticizer and methyl paraben as preservative. The pH, viscosity, and in vitro diffusion profiles were studied. The gels prepared with 8.0% of mucilage were found to be ideal and comparable with a commercial preparation.
Application of tannin gel to TRU aqueous waste treatment
International Nuclear Information System (INIS)
Batch experiments by simulated TRU aqueous waste using Eu, as a simulant of Am, were carried out to apply tannin gel to treatment of TRU aqueous waste, which has high nitric acid and Am concentration. From the results, reduction of adsorption amount of Eu by the impurities in the simulated waste was observed. However, the effect of the impurities will not become serious problem to construct practical process. Also, applicability of denitration by formic acid to pH conditioning for adsorption by tannin gel was examined to reduce the salt as a secondary waste arising from the neutralization for the pH conditioning. From the results of the batch experiments by the simulated waste containing formic acid, enhancement of Eu adsorption amount by the formic acid was observed. The applicability of adsorption by the tannin gel and denitration by formic acid to TRU aqueous waste treatment becomes clear from the results. (authors)
Modification of sol-gel thin films by ion implantation
International Nuclear Information System (INIS)
In order to densify and to improve the physical properties, TiO2 sol-gel films, about 100 nm in thickness, on silica glass or silicon wafer were implanted with Ar+ or B+ ions. The refractive index of the as-dried films increased and the IR absorption band of OH disappeared after Ar+ implantation. Drying and densification of sol-gel films were enhanced by Ar+ implantation. On the other hand, the refractive index and the thickness of the films hardly changed with B+ implantation. However, IR absorption bands of B-O bond were observed after B+ implantation. This suggests that sol-gel films could be chemically modified by ion implantation with reactive ion species
Creep and brittle failure of a protein gel under stress
Leocmach, Mathieu; Divoux, Thibaut; Manneville, Sébastien
Biomaterials such as protein or polysaccharide gels are known to behave qualitatively as soft solids and to rupture under an external load. Combining optical and ultrasonic imaging to shear rheology we show that the failure scenario of a protein gel is typical of brittle solids: after a power-law creep regime fully accounted for by linear viscoelasticity and homogeneous deformation, fractures nucleate and grow logarithmically perpendicularly to shear up to sudden rupture. A single equation accounting for those two successive processes nicely captures the full rheological response. The failure time follows a decreasing power-law with the applied shear stress strongly reminiscent of the Basquin law of fatigue for solids. These results are in excellent agreement with recent fiber-bundle models that include damage accumulation on elastic fibers and exemplify protein gels as model brittle soft solids.
Synthesis and characterization of nano-sized silica gels
International Nuclear Information System (INIS)
Silica gels with the high specific surface area and the high adsorption activity have been prepared from water-glass and HCl through the process of adding surfactant. DTA-TGA, BET, XRD, IR, TEM and some other methods are used to characterize the structure and performance of silica gels. The optimum technical conditions are as fallows: water-glass content, 40 g/L; HCl concentration, 5 mol/L; surfactant content, 50 g/L; calcining temperature, 600 degree C; aging time, 1 h. The specific surface area of the silica gel is found to be 998 m2/g. The static sorption capacity for zirconium reaches 0.344 mmol/g
Manufacture of Regularly Shaped Sol-Gel Pellets
Leventis, Nicholas; Johnston, James C.; Kinder, James D.
An extrusion batch process for manufacturing regularly shaped sol-gel pellets has been devised as an improved alternative to a spray process that yields irregularly shaped pellets. The aspect ratio of regularly shaped pellets can be controlled more easily, while regularly shaped pellets pack more efficiently. In the extrusion process, a wet gel is pushed out of a mold and chopped repetitively into short, cylindrical pieces as it emerges from the mold. The pieces are collected and can be either (1) dried at ambient pressure to xerogel, (2) solvent exchanged and dried under ambient pressure to ambigels, or (3) supercritically dried to aerogel. Advantageously, the extruded pellets can be dropped directly in a cross-linking bath, where they develop a conformal polymer coating around the skeletal framework of the wet gel via reaction with the cross linker. These pellets can be dried to mechanically robust X-Aerogel.
Study of the characterization and formulation of the decontamination gels
International Nuclear Information System (INIS)
To develop a chemical gel decontamination technology for a removal of non-fixed contaminants during the maintenance and decommissioning works of high radiation hot cells which have been used for a recycling or treatment of spent fuels we have prepare gels with CAB-O-SIL M-5 or Aerosil 380 as viscosifier and some non-ionic surfactants such as diethylene glycol hexyl ether, triethylene glycol dodecyl ether, polyethylene glycol 600, and triethylene glycol butyl ether. Surfactants are playing important roles in manipulating the properties of decontamination the gels. We have found the CAB-O-SIL with triethylene glycol butyl ether and Aerosil with triethylene glycol dodecyl ether systems promising for the decontamination work
Densification and crystallization behaviour of colloidal cordierite-type gels
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Full Text Available Three cordierite-type gels were prepared from an aqueous solution of Mg(NO32, a boehmite sol and silica sols of very small particle sizes. The effect of varying the silica particle size on the crystallization and densification behaviour was studied. Phase development was examined by thermal analysis and X-ray diffraction, while the densification behaviour was characterized by measuring the linear shrinkage of pellets. The activation energy of densification by viscous flow was determined using the Franckel model for non-isothermal conditions and a constant heating rate. The results show that spinel crystallizes from the colloidal gels prior to cristobalite, and their reaction gives a-cordierite, which is specific for three-phase gels. Decreasing the silica particles size lowers the cristobalite crystallization temperature and the a-cordierite formation temperature. The activation energy of densification by viscous flow is lower and the densification more efficient, the smaller the silica particles are.
Preparation and characterization of hydrophobic superparamagnetic magnetite gel
International Nuclear Information System (INIS)
The present study describes the preparation and analysis of a highly concentrated hydrophobic oleic acid-coated magnetite gel. By contrast to conventional techniques to prepare magnetic fluids, herein the oleic acid was introduced as a reactant during the initial crystallization phase of magnetite that was obtained by the co-precipitation of Fe(II) and Fe(III) salts by addition of ammonium hydroxide. The resulting gelatinous hydrophobic magnetite was characterized in terms of morphology, particle size, magnetic properties, crystal structure, and hydrophobicity/hydrophilicity. This magnetic gel exhibited superparamagnetism with a saturation magnetization of 46.0 emu/g at room temperature and could be well dispersed both in polar and nonpolar carrier liquids. This protocol produced highly concentrated hydrophobic magnetic gel for biopolymer encapsulations
Sol-gel-derived optical pH sensors
Lacan, Pascale; LeGall, P.; Rigola, Jeannine; Lurin, Christian L.; Wettling, D.; Guizard, Christian; Cot, L.
The sol-gel process has been successfully used for preparing amorphous and transparent oxide materials doped with organic molecules. This paper reports on the possibility of using sol-gel materials as host matrices for organic dyes in order to perform optical pH sensors. Different materials have been investigated so as to study the influence of some characteristics (porosity, hydrophilicity, hydrophobicity...) on the dye optical behavior. Results will be presented for microporous silica and heteropolysiloxanes which are organic/inorganic composites materials obtained from ormosil precursors known to provide versatile systems. Preliminary experiments have been carried out with sol-gel thin films doped with fluorescein as pH indicator and coated onto flat glass substrates. Dynamic range and response time curves are reported for the different sensors. Problems of signal losses (leachability, dye degradation...), sensor lifetime and dye stability within the different matrices are also discussed.
Strain identification in Rhizobium by starch gel electrophoresis of isoenzymes
DEFF Research Database (Denmark)
Engvild, Kjeld Christensen; Nielsen, G.
Sonieated extracts of rhizobia, especiaUy Rhizobium leguminosarum from pea and vetch, were run in horizontal starch gel electrophoresis in the cold. The rhizobia were grown on agar on a slime suppressing substrate of tryptone-yeast extract-CaCl2 with small amounts of mannitol, sorbitol and arabinose and other sugars as enzyme inducers. After electrophoresis the gels were separated into several slabs by a gel cutter. Each slab was stained for a particular enzyme. Among numerous enzyme systems tested we found useful variation in esterases (EC 18.104.22.168, EC 220.127.116.11), 3-hydroxybutyrate dehydrogenase (EC 184.108.40.206), mannitol dehydrogenase (EC 22.214.171.124), and arabinose dehydrogenase (EC 22.214.171.124). It was possible to distinguish at least 7 different types of pea rhizobia among 16 strains isolated from one batch of 5 kg soil.
Non-diffusing photochromic gel for optical computed tomography phantoms
Jordan, K.
This study examines photochromic response in radiation sensitive hydrogels. Genipin, crosslinked, gelatin gel can support high resolution images because the chromophores do not diffuse. A low power, 633 nm He-Ne laser was used to write lines into the gels by a photobleaching reaction. Optical cone-beam computed tomography (CBCT) scans mapped the high resolution images in 3D with 0.25 mm voxel resolution. A straight line was written into a deformed gel and then readout in its relaxed, initial shape. The curved, photo-bleached line demonstrated deformable 3D dosimetry is possible with this system to the balloon edge. High resolution, photochromic images provide key information for characterizing optical CT scanners and 3D dosimeters. Many, ionizing radiation, dosimeter materials demonstrate either a photochromic or photothermal response, allowing this approach to be widely used in quantitative 3D scanning.
Surface structure of polymer Gels and emerging functions
International Nuclear Information System (INIS)
We report the surface structure of polymer gels on a submicrometer scale during the volume phase transition. Sponge-like domains with a mesoscopic scale were directly observed in water by using at atomic force microscope (AFM). The surface structure characterized by the domains is discussed in terms of the root-mean-square roughness and the auto-correlation function, which were calculated from the AFM images. In order to demonstrate the role of surface structure in determining the macroscopic properties of film-like poly (N-isopropylacrylamide: NIPA) gels. It was found that the temperature dependence, as well as the absolute values of the static contact angle, were strongly dependent on the bulk network inhomogeneities. The relation between the mesoscopic structure and the macroscopic properties is qualitatively discussed in terms of not only the changes in the chemical, but also in the physical, surface properties of the NIPA gels in response to a temperature change
Optical Sensors for Biomolecules Using Nanoporous Sol-Gel Materials
Fang, Jonathan; Zhou, Jing C.; Lan, Esther H.; Dunn, Bruce; Gillman, Patricia L.; Smith, Scott M.
An important consideration for space missions to Mars is the ability to detect biosignatures. Solid-state sensing elements for optical detection of biological entities are possible using sol-gel based biologically active materials. We have used these materials as optical sensing elements in a variety of bioassays, including immunoassays and enzyme assays. By immobilizing an appropriate biomolecule in the sol-gel sensing element, we have successfully detected analytes such as amino acids and hormones. In the case of the amino acid glutamate, the enzyme glutamate dehydrogenase was the immobilized molecule, whereas in the case of the hormone cortisol, an anti-cortisol antibody was immobilized in the sensing element. In this previous work with immobilized enzymes and antibodies, excellent sensitivity and specificity were demonstrated in a variety of formats including bulk materials, thin films and fibers. We believe that the sol-gel approach is an attractive platform for bioastronautics sensing applications because of the ability to detect a wide range of entities such as amino acids, fatty acids, hopanes, porphyrins, etc. The sol-gel approach produces an optically transparent 3D silica matrix that forms around the biomolecule of interest, thus stabilizing its structure and functionality while allowing for optical detection. This encapsulation process protects the biomolecule and leads to a more "rugged" sensor. The nanoporous structure of the sol-gel matrix allows diffusion of small target molecules but keeps larger, biomolecules immobilized in the pores. We are currently developing these biologically active sol-gel materials into small portable devices for on-orbit cortisol detection
Gel clot bacterial endotoxin test of FDG: Indian scenario
International Nuclear Information System (INIS)
The bacterial endotoxin test (BET) performed using gel clot method is a 60-min test and typically performed after the decay of the 2-(18F) fluoro-2-deoxy-D-glucose (18F-FDG) sample to determine the endotoxin content. The objective of this study protocol was to perform BET testing of 18F-FDG by gel clot method. Ten random decayed samples of the 18F-FDG were subjected to the gel clot BET. The assay was performed with undiluted 18F-FDG and at four different maximum valid dilutions of 1:10, 1:100, 1:350 and 1:700 (total number of tests = 100). The sensitivity of the LAL reagent used was 0.125 EU/ml. Endotoxin dilutions were freshly prepared from control standard endotoxin (CSE) stock solution for each 18F-FDG batch testing. If the gel had formed and remained intact in the bottom of the reaction tube after an inversion of 180 °, the test was considered positive. Any other state of the reaction mixture constituted a negative test. In the undiluted samples, the measured pH (7.05) was well within the acceptable range (i.e. 6.0-8.0) for the gel clot assay. Of the 10 undiluted 18F-FDG batches and all the diluted samples, none gelled after 60-min incubation period at 37° C. However, the undiluted 18F-FDG did inhibit gel formation at the lysate sensitivity of 0.125 EU/ml. The total volume of FDG produced was 16 ml in the synthesis module. The total 18F-FDG preparation at any time p>18F-FDG preparation at any time did not contain more than 8 EU (0.5 EU/ml x 16 ml). Thus, the product is safe for human administration. (author)
Diffusion of ion-exchanging electrolytes in montmorillonite gels
International Nuclear Information System (INIS)
The primary contributions of this work are: (1) Development of a unique radially perfused diffusion cell suitable for measuring transient diffusion rates in compacted, highly adsorbing and swelling porous media such as montmorillonite clay gels; (2) examination of the effective diffusion coefficient (D6) of electrolytes in montmorillonite clay gels; and (3) Measurement of the transient diffusion rates of cesium, chloride and tritium in 15 w/o montmorillonite clay gels at pH 9 and sodium chloride backgrounds of 10-1 to 10-3 kmol/m3. Results are interpreted by using the dilute limit of the multicomponent transport equations derived for species migration in a single clay pore after macroscopic averaging. The tortuosity of the clay gel is found by tritium diffusion. Transient chloride diffusion rates are found to be at molecular rates. Negative adsorption of anions from the clay gel, required for an a priori prediction of chloride profiles, are calculated from site-binding theory. Surface diffusion is the primary mode of cesium transport in montmorillonite clay gels. Migration of cesium is primarily along the inner Helmholtz plane of clay particles. The primary implication for the montmorillonite clay-based packing as a nuclear waste migration barrier is that surface diffusion must be included to describe properly diffusion rates of either anions or cations. Currently surface diffusion is neglected and cesium penetration into ths neglected and cesium penetration into the packing is drastically underestimated. Penetration depths of anions is grossly overestimated. In either case, the appropriate diffusion coefficient of ions in compacted packing will be in considerable error relative to current design recommendations
Polyelectrolyte gels as bending actuators: modeling and numerical simulation
Wallmersperger, Thomas; Keller, Karsten; Attaran, Abdolhamid
Polyelectrolyte gels are ionic electroactivematerials. They have the ability to react as both, sensors and actuators. As actuators they can be used e.g. as artificial muscles or drug delivery control; as sensors they may be used for measuring e.g. pressure, pH or other ion concentrations in the solution. In this research both, anionic and cationic polyelectrolyte gels placed in aqueous solution with mobile anions and cations are investigated. Due to external stimuli the polyelectrolyte gels can swell or shrink enormously by the uptake or delivery of solvent. In the present research a coupled multi-field problem within a continuum mechanics framework is proposed. The modeling approach introduces a set of equations governing multiple fields of the problem, including the chemical field of the ionic species, the electrical field and the mechanical field. The numerical simulation is performed by using the Finite Element Method. Within the study some test cases will be carried out to validate our model. In the works by Gülch et al., the application of combined anionic-cationic gels as grippers was shown. In the present research for an applied electric field, the change of the concentrations and the electric potential in the complete polymer is simulated by the given formulation. These changes lead to variations in the osmotic pressure resulting in a bending of different polyelectrolyte gels. In the present research it is shown that our model is capable of describing the bending behavior of anionic or cationic gels towards the different electrodes (cathode or anode).
Implementation of an efficient workflow process for gel dosimetry using 3D Slicer
Alexander, K. M.; Pinter, C.; Andrea, J.; Fichtinger, G.; Schreiner, L. J.
One challenge in gel dosimetry is the manipulation and analysis of complex data sets from different systems. In this paper, we describe a simple and fast gel dosimetry analysis tool for radiation therapy dose deliveries. Using the open source medical imaging software 3D Slicer, an extension was designed and implemented for the purpose of importing treatment planning system dose, CT imaging from simulation and at treatment, and optical CT gel dosimeter data. The extension also allows for calibration of gel dosimeter data, registration, and comparison of 3D dose distributions. The development of an open source gel dosimetry processing environment may help adoption of gels in the clinic.
Water and tissue equivalency of some gel dosimeters for photon energy absorption
International Nuclear Information System (INIS)
The mass energy absorption coefficients,?en/?, effective atomic numbers for photon energy absorption, ZPEAeff, and effective electron numbers for photon-energy absorption, NPEAeff, is calculated for 14 polymer gel dosimeter, five gel dosimeter, soft tissue and water, in the energy range from 1 keV to 20 MeV. The ZPEAeff(Gel)/ZPEAeff(Tissue) and NPEAeff(Gel)/NPEAeff (Tissue) are used to evaluate the tissue equivalency. - Highlights: • Tissue and water equivalency of gel dosimeters is investigated. • Effective atomic and electron numbers for gel dosimeters are calculated, with respect to the photon energy absorption. • Calculations are compared to previous work for verification
Nanoscaled filled sol-gel hybrid materials for powder coatings
Sepeur, Stefan; Dittfurth, Carola; Muhle, Jörg; Poppe, Andreas; Schmidt, Helmut K.
The sol-gel process has been applied for the synthesis of inorganic-organic powder materials. For this purpose, low reactivity and, for reasons of comparison, nanoscaled sol-gel precursors and nanoscaled silica filler were used to synthesize a low molecular weight inorganic-organic composite which was meltable between 85°C and 100°C and curable at temperatures of 150°C - 200°C. The powders were used for electrostatic coating of aluminum sheets. The resulting coatings of the unfilled system ex...
Functionalization of sol-gel zirconia composites with europium complexes
International Nuclear Information System (INIS)
Different sol-gel strategies based on functionalization of ZrO2:Eu microparticles with 1,10-phenanthroline (phen) and incorporation of colloidal Eu(phen)2(NO3)3 into zirconia have been used to obtain hybrid sol-gel composites with controlled optical properties. The process leads to materials with quantum yields of about 48 % monitoring the 615 nm emission line at 350 nm excitation. Excitation/luminescence spectroscopy, diffuse reflectance spectroscopy and X-ray diffraction have been used to characterize the hybrid zirconia composites. (orig.)
EXAFS analysis of blue luminescence in polyoxytungstate citrate gels
International Nuclear Information System (INIS)
Remarkable color changes can be seen when ammonium metatungstate - citric acid gels are submitted to sunlight. The colors strongly depend of the pH values of the precursor solution. Luminescence measurements reveal that gels at pH 7 exhibit a strong blue emission resulting from the presences of WO42- tetrahedra while a slight green emission is due to WO66- octahedra. The shift in equilibrium from octahedral to tetrahedral coordination upon increase in pH is confirmed by detailed EXAFS analysis. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Inorganic Sensing Using Organofunctional Sol-Gel Materials
Carrington, Nathan A.; Xue, Zi-ling
This Account describes recent work in the development and applications of sol-gel sensors for concentrated strong acids/bases and metal ions. The use of sol-gel films doped with organic indicators for the optical sensing of concentrated strong acids (HCl 1-10 M) and bases (NaOH 1-10 M) has been explored, and the development of dual optical sensor approaches for ternary systems (HCl-salt-H2O and NaOH-alcohol-H2O) to give acid and salt as well as base and alcohol concentrations is discussed. Th...
Methods for immobilizing nucleic acids on a gel substrate
Mirzabekov, Andrei Darievich (Moscow, RU); Proudnikov, Dimitri Y. (Samara, RU); Timofeev, Edward N. (Moscow, RU); Kochetkova, Svetlana V. (Moscow, RU); Florentiev, Vladimir L. (Moscow, RU); Shick, Valentine V. (Moscow, RU)
A method for labeling oligonucleotide molecules, and for immobilizing oligonucleotide and DNA molecules is provided comprising modifying the molecules to create a chemically active group, and contacting activated fluorescent dyes to the region. A method for preparing an immobilization substrate is also provided comprising modifying a gel to contain desired functional groups which covalently interact with certain moieties of the oligonucleotide molecules. A method for immobilizing biomolecules and other molecules within a gel by copolymerization of allyl-substituted oligonucleotides, DNA and proteins with acrylamide is also provided.
Irradiation of linear polyethylene - Partitioning between sol and gel.
Rijke, A. M.; Mandelkern, L.
Investigation of the importance of chain-scission processes and of the applicability of the general theory of network formation to polyethylene with respect to critical conditions for gelation, using molecular weight fractions of linear polyethylene irradiated at 133 C. The partitioning between sol and gel was found to adhere to the theory just beyond the gel point. Deviations from theory occurred as the irradiation dosage was increased. It was concluded that main-chain scission at the temperatures concerned is not a significant process.
Pulsed-Field Gel Electrophoresis of Pseudomonas aeruginosa.
Hu, Honghua; Manos, Jim
Pulsed-field gel electrophoresis (PFGE) is a technique used for the separation of high molecular weight restriction fragments from digested bacterial genomic DNA on a gel matrix by applying an electric field that periodically changes direction. PFGE has been shown to be the most discriminatory and reproducible bacterial strain typing technique available. It is considered the 'gold standard' in epidemiological studies of pathogenic and nonpathogenic microorganisms. This chapter provides a detailed method for using PFGE in the genotyping of the opportunistic Gram-negative bacterial pathogen Pseudomonas aeruginosa. PMID:25862056
Generation of monodisperse gel emulsions in a microfluidic device
Priest, Craig; Herminghaus, Stephan; Seemann, Ralf
We demonstrate that high dispersed phase volume fraction emulsions (i.e., gel emulsions) can be prepared in situ for microfluidic applications. Previously, the production of gel-like emulsions in microfluidic devices, where the droplet size is less than the length-scale of the channel, required multistep splitting of larger droplets in a branched microchannel network. Instead, we employ an abrupt change in the aspect ratio of a single microchannel to rapidly destabilize a confined coflowing stream, forming highly monodisperse droplets (coefficient of variance emulsions can be prepared in a single production step.
An Innovative Concept Gel to Prevent Skin Aging
Adele Sparavigna; Beatrice Tenconi; Ileana Deponti; Francesco Scarci; Maurizio Caserini; Federico Mailland
The study aimed to evaluate the instrumental and clinical properties of an innovative gel formulation for anti-aging treatment. This was an open, non-controlled study, where the eligible subjects, divided into three subgroups according to age, had to perform a single dose application of the gel on the face for a short-term evaluation and a 4-week repeated use, twice a day, for a long-term evaluation. Instrumental and clinical evaluations had to be performed mono-lateral...
Scaffold architecture and fibrin gels promote meniscal cell proliferation
International Nuclear Information System (INIS)
Stability of the knee relies on the meniscus, a complex connective tissue with poor healing ability. Current meniscal tissue engineering is inadequate, as the signals for increasing meniscal cell proliferation have not been established. In this study, collagen scaffold structure, isotropic or aligned, and fibrin gel addition were tested. Metabolic activity was promoted by fibrin addition. Cellular proliferation, however, was significantly increased by both aligned architectures and fibrin addition. None of the constructs impaired collagen type I production or triggered adverse inflammatory responses. It was demonstrated that both fibrin gel addition and optimized scaffold architecture effectively promote meniscal cell proliferation
A conductive gel for the plotting of equipotential lines
Elizalde-Torres, J.; González-Cardel, M.; Vega-Murguía, E. J.; Castillo-González, I.; Rodríguez-Nava, M.
This paper presents the development of a conductive gel that can be used to measure the electrical potential differences on its surface, and has enough consistency to plot equipotential lines. It has a gelation time of less than 10?min, and is suitable for implementing learning experiences in a physics teaching laboratory in a 90?min session. To evaluate the gel, voltage measurements were made on its surface by applying an alternating electric current with frequencies of 60 and 1000?Hz and an amplitude of 200?mV using iron steel electrodes with several geometrics. Some equipotential lines were also identified using a water soluble marker.
TOPICAL REVIEW: Encapsulation of biomolecules in silica gels
Livage, Jacques; Coradin, Thibaud; Roux, Cécile
A wide variety of biomolecules, ranging over proteins, enzymes, antibodies and even whole cells, have been embedded within sol-gel glasses. They retain their bioactivity and remain accessible to external reagents by diffusion through the porous silica. Sol-gel glasses can be cast into desired shapes and are optically transparent, so it is possible to couple optics and bioactivity to make photonic devices and biosensors. The high specificity and sensitivity of enzymes and antibodies allows the detection of traces of chemicals. Entrapped living cells can be used for the production of metabolites, the realization of immunoassays and even for cell transplantation.
Scaffold architecture and fibrin gels promote meniscal cell proliferation
Energy Technology Data Exchange (ETDEWEB)
Pawelec, K. M., E-mail: email@example.com, E-mail: firstname.lastname@example.com; Best, S. M.; Cameron, R. E. [Cambridge Centre for Medical Materials, Materials Science and Metallurgy Department, University of Cambridge, Cambridge CB3 0FS (United Kingdom); Wardale, R. J., E-mail: firstname.lastname@example.com, E-mail: firstname.lastname@example.com [Division of Trauma and Orthopaedic Surgery, Department of Surgery, University of Cambridge, Cambridge CB2 2QQ (United Kingdom)
Stability of the knee relies on the meniscus, a complex connective tissue with poor healing ability. Current meniscal tissue engineering is inadequate, as the signals for increasing meniscal cell proliferation have not been established. In this study, collagen scaffold structure, isotropic or aligned, and fibrin gel addition were tested. Metabolic activity was promoted by fibrin addition. Cellular proliferation, however, was significantly increased by both aligned architectures and fibrin addition. None of the constructs impaired collagen type I production or triggered adverse inflammatory responses. It was demonstrated that both fibrin gel addition and optimized scaffold architecture effectively promote meniscal cell proliferation.
Scaffold architecture and fibrin gels promote meniscal cell proliferation
Directory of Open Access Journals (Sweden)
K. M. Pawelec
Full Text Available Stability of the knee relies on the meniscus, a complex connective tissue with poor healing ability. Current meniscal tissue engineering is inadequate, as the signals for increasing meniscal cell proliferation have not been established. In this study, collagen scaffold structure, isotropic or aligned, and fibrin gel addition were tested. Metabolic activity was promoted by fibrin addition. Cellular proliferation, however, was significantly increased by both aligned architectures and fibrin addition. None of the constructs impaired collagen type I production or triggered adverse inflammatory responses. It was demonstrated that both fibrin gel addition and optimized scaffold architecture effectively promote meniscal cell proliferation.
2D Electrophoresis Gel Image and Diagnosis of a Disease
Kim, G; Kim, Gene; Kim, MyungHo
The process of diagnosing a disease from the 2D gel electrophoresis image is a challenging problem. This is due to technical difficulties of generating reproducible images with a normalized form and the effect of negative stain. In this paper, we will discuss a new concept of interpreting the 2D images and overcoming the aforementioned technical difficulties using mathematical transformation. The method makes use of 2D gel images of proteins in serums and we explain a way of representing the images into vectors in order to apply machine-learning methods, such as the support vector machine.
Functionalization of sol-gel zirconia composites with europium complexes
Energy Technology Data Exchange (ETDEWEB)
Danchova, Nina; Gutzov, Stoyan [Sofia Univ. ' St Kliment Ohridski' (Bulgaria). Dept. of Physical Chemistry
Different sol-gel strategies based on functionalization of ZrO{sub 2}:Eu microparticles with 1,10-phenanthroline (phen) and incorporation of colloidal Eu(phen){sub 2}(NO{sub 3}){sub 3} into zirconia have been used to obtain hybrid sol-gel composites with controlled optical properties. The process leads to materials with quantum yields of about 48 % monitoring the 615 nm emission line at 350 nm excitation. Excitation/luminescence spectroscopy, diffuse reflectance spectroscopy and X-ray diffraction have been used to characterize the hybrid zirconia composites. (orig.)
Mechanical properties of syndiotactic polypropylene (sPP) gels: the effects of temperature and solute concentration
Okoshi, Ryusuke; Hotta, Atsushi
The effects of the solute concentration on the microstructures and the mechanical properties of quenched syndiotactic polypropylene (sPP) gels were investigated. Our group has previously reported a highly resilient sPP gel quenched using liquid nitrogen (Gel LN). In this research, sPP/decahydronaphtalene gels were prepared varying the sPP concentrations from 5 to 20 wt%. Compression test was carried out to evaluate the mechanical properties. Scanning electron microscopy (SEM) was conducted to analyze the microstructures. Gel LN with the sPP concentration of 20 wt% presented a high fracture stress of 2400 kPa. A high fracture strain of 70% was also observed for all Gel LN samples. By contrast, sPP gels with the sPP concentration of 20 wt% cooled at 25 degrees C (Gel 25) showed lower fracture stress of 480 kPa. The fracture strain of Gel 25 ranged from 21 to 37% depending on the sPP concentrations. The SEM results revealed that the Gel LN samples had homogeneous networks regardless of the sPP concentrations. The Gel 25, however, possessed inhomogeneous networks with spherulites. It was therefore concluded that the strengthening of the sPP gels could be effectively achieved by Gel LN regardless of the sPP concentrations.
Solvent cleanup using base-treated silica gel solid adsorbent
International Nuclear Information System (INIS)
A solvent cleanup method using silica gel columns treated with either sodium hydroxide (NaOH) or lithium hydroxide (LiOH) has been investigated. Its effectiveness compares favorably with that of traditional wash methods. After treatment with NaOH solution, the gels adsorb HNO3, dibutyl phosphate (DBP), UO22+, Pu4+, various metal-ion fission products, and other species from the solvent. Adsorption mechanisms include neutralization, hydrolysis, polymerization, and precipitation, depending on the species adsorbed. Sodium dibutyl phosphate, which partially distributes to the solvent from the gels, can be stripped with water; the stripping coefficient ranges from 280 to 540. Adsorption rates are diffusion controlled such that temperature effects are relatively small. Recycle of the gels is achieved either by an aqueous elution and recycle sequence or by a thermal treatment method, which may be preferable. Potential advantages of this solvent cleanup method are that (1) some operational problems are avoided and (2) the amount of NaNO3 waste generated per metric ton of nuclear fuel reprocessed would be reduced significantly. 19 references, 6 figures, 12 tables
Structure and arrested dynamics of colloidal gels of adhesive spheres
Solomon, Michael J.; Varadan, Priya
Suspensions of colloidal silica grafted with octadecyl hydrocarbon chains and dispersed in hexadecane form reversible physical gels below a critical temperature (Chen and Russel, J Colloid Interface Sci 141 564 1991). The gelation temperature is a function of the colloid volume fraction. The interparticle interaction of this system has been modeled with Baxter's model for adhesive spheres. The relationship between the onset of gelation in thermoreversible colloidal gels and the predicted phase behavior of adhesive spheres is unclear. We have measured the static structure factor and the coherent intermediate scattering function, f(q,t), of the thermoreversible gels for volume fractions between 0.01 and 0.1 by means of light scattering. The static structure factor of the gels is consistent with the structure of aggregated fractal clusters of finite extent. Below the gelation temperature, f(q,t) exhibits a long-time plateau whose magnitude is a function of the scattering vector q, temperature and volume fraction. The dependence of the temporal relaxation of f(q,t) on these quantities is discussed with regards to the recent model of Krall and Weitz (Phys Rev Lett 80 778 1998), the Baxter model for adhesive spheres, and the theory and phenomenology of the glass transition.
Immobilization of Brewing Yeast Cells by Sol-Gel Technique.
Czech Academy of Sciences Publication Activity Database
Prajzlerová, M.; Kuncová, Gabriela; Dostálek, P.
Praha, 2002, s. 119-122. [International BRG Workshop on Bioencapsulation /10./. Praha (CZ), 26.04.2002-28.04.2002] R&D Projects: GA MŠk OC 840.10 Keywords : cell immobilization * sol-gel technique * alginate Subject RIV: CI - Industrial Chemistry, Chemical Engineering
Immobilization of Brewing Yeast Cells by Sol-Gel Technique.
Czech Academy of Sciences Publication Activity Database
Dostálek, P.; ?epi?ka, J.; Fiala, J.; Prajzlarová, M.; Kuncová, Gabriela
2002. s. 17. [Technical Meeting EBC Brewing Science Group /4./. 04.09.2002-06.09.2002, Oporto] Institutional research plan: CEZ:AV0Z4072921 Keywords : brewing yeast cells * sol-gel technique * immobilization of living cells Subject RIV: CI - Industrial Chemistry, Chemical Engineering
Dose mapping of inhomogeneities positioned in radiosensitive polymer gels
International Nuclear Information System (INIS)
A gel matrix (gelatin), infused with acrylamide monomer and a crosslinking agent has been used as a three-dimensional dosimeter of X- and ?-rays are used in radiotherapy. Magnetic resonance imaging is used to create a parameter map of transverse relaxation time (T2) from which a map of absorbed dose is calculated. We are using the technique to investigate the interfacial radiation patterns resulting from the presence of implanted inhomogeneities in the gel phantom being irradiated, a concept which is as yet underdeveloped. The inhomogeneities, which may be either low or high density with respect to the surrounding medium, are designed to simulate the effects of air cavities or bone in the body and their effects on the absorbed dose during radiotherapy. This paper explores ways of introducing inhomogeneities into the gel and presents results of dose maps obtained post irradiation. An inherent problem of the dosimeter is the inhibition of polymerisation due to dissolved oxygen. Free radicals produced by the incident radiation are key to the polymerisation and crosslinking effects but are consumed by the dissolved oxygen. This paper describes the observed effects of oxygen contamination within a gel and suggests steps to be taken to minimise the problem
New decontamination techniques: chemical gels, electropolishing and abrasives
International Nuclear Information System (INIS)
The decommissioning of nuclear installations requires decontamination techniques that are efficient, simple to apply and producing a small amount of wastes, which are easy to process. With a view to this, three decontamination methods, which appear to be particularly suited to decommissioning, have been studied. These three methods are: - spraying of gels carrying chemical decontaminating agents, - electropolishing with a swab device, - abrasives blasting. After parametric tests on non-radioactive and active samples, the industrial application of these methods in the dismantling of installations was studied. These industrial applications concern: - decontamination of pieces coming from the German BWR ISAR by immersion and gel spraying, - decontamination, mainly by gel spraying, and dismantling of the BRENNILIS bituminisation plant, - decontamination of part of the cooling circuit of the graphite gas reactor G2 by gel spraying, - decontamination of a component of the FBR SuperPhenix, using dry abrasives blasting. During the first three applications, generated secondary wastes volume and form were determined. 33 tabs., 16 figs., 12 refs
Sol-gel matrices for direct colorimetric detection of analytes
Charych, Deborah H. (Albany, CA); Sasaki, Darryl (Albuquerque, NM); Yamanaka, Stacey (Dallas, TX)
The present invention relates to methods and compositions for the direct detection of analytes using color changes that occur in immobilized biopolymeric material in response to selective binding of analytes to their surface. In particular, the present invention provides methods and compositions related to the encapsulation of biopolymeric material into metal oxide glass using the sol-gel method.
Process of forming a sol-gel/metal hydride composite
Congdon, James W. (Aiken, SC)
An external gelation process is described which produces granules of metal hydride particles contained within a sol-gel matrix. The resulting granules are dimensionally stable and are useful for applications such as hydrogen separation and hydrogen purification. An additional coating technique for strengthening the granules is also provided.
Sol–gel coassembly of macroporous cylinders cladded optical fibers
International Nuclear Information System (INIS)
Highlights: • We develop a novel sol–gel cooperatively assembly method. • 3D microstructure fibers can be fabricated in a single step by sol–gel co-assembly. • Cylindrical inverse opals cladded optical fibers show face-centered cubic structure. • SEM images of transverse and longitudinal cross section are observed. • Transmission spectra show deep photonic band gaps up to 50%. - Abstract: In this paper, we provide a facile way to fabricate a microstructure fiber by coating a standard optical fiber with a silica inverse opal through a sol–gel coassembly method. Polystyrene (PS) colloidal suspension of microspheres and a hydrolyzed silicate precursor were added to the solvent together. With the evaporation of the solvent, the assembly of a PS colloidal template and the infiltration of voids of the spheres with silica gel were executed simultaneously to form a colloidal composite in a single step. After removal of the sacrificial colloidal template, a cylindrical inverse opal (CIO) cladded an optical fiber was obtained. Structural properties characterized by optical and scanning electron microscopy (SEM) and unique transmission spectra with photonic band gaps reveal the high quality of the silica CIOs, which can be used as fiber Bragg grating for optical communications
Fibrinopeptide A radioimmunoassay by the gel adsorption method
International Nuclear Information System (INIS)
The aim of these studies was to test the fibrinopeptide-A radioinmunoassay by the gel adsorption method for its clinical application, its validity and its accuracy concerning clinical questions. Fibrinopeptide-A levels (individual values) and the kinetics of fibrinopeptide-A liberation in vitro (FPA-formation curves) were therefore determined for 'normal persons' and patients with various illnesses. (orig./MG)
Fine patterning of thin sol-gel films
Krug, Herbert; Merl, Norbert; Schmidt, Helmut K.
An embossing technique was used to fabricate surface reliefs in organically modified ceramics of the Ormocer type, synthesized via the sol-gel route. Embossing techniques for these materials are described and results of embossed grids and gratings with up to 2400 lines/mm and peak-to-trough values up to 3 µm are presented.
i-Gel Supraglottic Airway for Inexperienced Anesthesia Residents
Directory of Open Access Journals (Sweden)
Hiroyuki Kobinata
Full Text Available i-gel (Intersurgical Ltd., Wokingham, UK is a new supraglottic airway device with a cuff made of thermoplastic elastomer gel. We retrospectively studied easiness of insertion and troubles in ventilation when this device was used by less experienced anesthesiologists. Consecutive eleven cases undergoing surgery under general anesthesia were studied. i-gel was successfully inserted in 7 cases (63% at the first attempt, 2 cases at the second attempt without changing the size. In one case, the size was changed at the second attempt, which resulted in the successful insertion. There was one case of failed insertion even at the second attempt. Fiberoptic observation of the glottis showed direct contact of the cuff to the arytenoids cartilage in cases with successful insertion, however, spastic glottis, defined as contact of vocal cords was observed in 4 cases, and down-folding of the epiglottis was observed in 2 cases. During maintenance of anesthesia, ventilation trouble was observed in 3 cases. We conclude that i-gel should only be used with sufficient knowledge, preparations, skills or support from experienced physician to solve problems related to the safe use of supraglottic airway devices.
Scaling Analysis of Surfactant Templated Polyacrylamide Gel Surfaces
Chakrapani, M; Van Winkle, D; Rikvold, P A; Chakrapani, Mukundan
Surfaces of surfactant-templated polyacrylamide hydrogels were imaged by atomic force microscopy (AFM), and the surface morphology was studied by numerical scaling analysis. The templated gels were formed by polymerizing acrylamide plus a cross-linker in the presence of surfactants, which were then removed by soaking in distilled water. Gels formed in the presence of over 20% surfactant (by weight) formed clear, but became opaque upon removal of the surfactants. Untemplated gels formed and remained clear. The surface morphology of the gels was studied by several one- and two-dimensional numerical scaling methods. The surfaces were found to be self-affine on short length scales, with a roughness (Hurst) exponent in the range 0.85 to 1, crossing over to a constant root-mean-square surface width on long scales. Both the crossover length between these two regimes and the saturation value of the surface width increased significantly with increasing surfactant concentration, coincident with the increase in opacity....
Polymerase Chain Reaction (PCR) and Gel Electrophoresis Powerpoint
The HURI SURI project is developing a regional biotechnology workforce pipeline by expanding and supporting biotechnology research experiences for Jamestown Community College (JCC) undergraduates and disseminating these research experiences and materials to area high school teachers and students. This 15 slide presentation provides an introduction to DNA and explains polymerase chain reactions and gel electrophoresis. Many diagrams are included to help explain the concepts.
Fluorine profiling after application of various anti-caries gels
International Nuclear Information System (INIS)
Two newly developed caries-preventing gels were tested together with Elmex on pre-school children over a time of 3 years. Proton-induced gamma-ray emission spectrometry (PIGE) was used to measure the fluorine profiles in milk teeth (incisors). In accordance with the clinical statement the results allow to produce a new anti-caries drug. (orig.)
Photolithography fabrication of sol-gel ridge waveguides
Sara, Rahmani; Touam, Tahar; Blanchetiere, Chantal; Saddiki, Z.; Saravanamuttu, Kalaichelvi; Du, Xin M.; Chrostowski, Jacek; Andrews, Mark P.; Najafi, S. Iraj
We report on fabrication of ridge waveguides in UV-light sensitive glass sol-gel thin films, deposited on silicon substrate, using a simple photolithography process. The single-layer films are prepared at low temperature and deep UV-light (DUV) is employed to make the waveguides. The effect of fabrication parameters on waveguide shape is investigated.
Electrically tunable coherent optical absorption in graphene with ion gel.
Thareja, Vrinda; Kang, Ju-Hyung; Yuan, Hongtao; Milaninia, Kaveh M; Hwang, Harold Y; Cui, Yi; Kik, Pieter G; Brongersma, Mark L
We demonstrate electrical control over coherent optical absorption in a graphene-based Salisbury screen consisting of a single layer of graphene placed in close proximity to a gold back reflector. The screen was designed to enhance light absorption at a target wavelength of 3.2 ?m by using a 600 nm-thick, nonabsorbing silica spacer layer. An ionic gel layer placed on top of the screen was used to electrically gate the charge density in the graphene layer. Spectroscopic reflectance measurements were performed in situ as a function of gate bias. The changes in the reflectance spectra were analyzed using a Fresnel based transfer matrix model in which graphene was treated as an infinitesimally thin sheet with a conductivity given by the Kubo formula. The analysis reveals that a careful choice of the ionic gel layer thickness can lead to optical absorption enhancements of up to 5.5 times for the Salisbury screen compared to a suspended sheet of graphene. In addition to these absorption enhancements, we demonstrate very large electrically induced changes in the optical absorption of graphene of ?3.3% per volt, the highest attained so far in a device that features an atomically thick active layer. This is attributable in part to the more effective gating achieved with the ion gel over the conventional dielectric back gates and partially by achieving a desirable coherent absorption effect linked to the presence of the thin ion gel that boosts the absorption by 40%. PMID:25671369
Directory of Open Access Journals (Sweden)
Dhrupesh panchal
Full Text Available Over the past few decades, advances in the in situ gel technologies have spurred development in manymedical and biomedical applications including controlled drug delivery. Many novel in situ gel baseddelivery matrices have been designed and fabricated to fulfill the ever increasing needs of thepharmaceutical and medical fields. In situ gelling systems are liquid at room temperature but undergogelation when in contact with body fluids or change in pH. In situ gel forming drug delivery is a type ofmucoadhesive drug delivery system. The formation of gel depends on factors like temperaturemodulation, pH change, presence of ions and ultraviolet irradiation from which the drug gets released ina sustained and controlled manner. Nasal delivery is a promising drug delivery option where commondrug administrations such as intravenous, intramuscular or oral are inapplicable. Recently, it has beenshown that many drugs have better bioavailability by nasal route than the oral route. This has beenattributed to rich vasculature and a highly permeable structure of the nasal mucosa coupled withavoidance of hepatic first-pass elimination, gut wall metabolism and/or destruction in thegastrointestinal tract. The physiology of the nose presents obstacles but offers a promising route for noninvasivesystemic delivery of numerous therapies and debatably drug delivery route to the brain. Thusthis review focuses on nasal drug delivery, various aspects of nasal anatomy and physiology, nasal drugabsorption mechanisms, various nasal drug delivery systems and their applications in drug delivery.
Sol–gel coassembly of macroporous cylinders cladded optical fibers
Energy Technology Data Exchange (ETDEWEB)
Li, Xia; Tian, Jing; Lv, Zhijuan [Jiangsu Laboratory of Advanced Functional Materials, College of Physics and Electronic Engineering, Changshu Institute of Technology, Changshu 215500 (China); Guo, Wenhua, E-mail: email@example.com [Jiangsu Laboratory of Advanced Functional Materials, College of Physics and Electronic Engineering, Changshu Institute of Technology, Changshu 215500 (China); School of Physics and Technology, Nanjing Normal University, Key Laboratory on Opto-Electronic Technology of Jiangsu Province, Nanjing 210046 (China); Wang, Ming [School of Physics and Technology, Nanjing Normal University, Key Laboratory on Opto-Electronic Technology of Jiangsu Province, Nanjing 210046 (China)
Highlights: • We develop a novel sol–gel cooperatively assembly method. • 3D microstructure fibers can be fabricated in a single step by sol–gel co-assembly. • Cylindrical inverse opals cladded optical fibers show face-centered cubic structure. • SEM images of transverse and longitudinal cross section are observed. • Transmission spectra show deep photonic band gaps up to 50%. - Abstract: In this paper, we provide a facile way to fabricate a microstructure fiber by coating a standard optical fiber with a silica inverse opal through a sol–gel coassembly method. Polystyrene (PS) colloidal suspension of microspheres and a hydrolyzed silicate precursor were added to the solvent together. With the evaporation of the solvent, the assembly of a PS colloidal template and the infiltration of voids of the spheres with silica gel were executed simultaneously to form a colloidal composite in a single step. After removal of the sacrificial colloidal template, a cylindrical inverse opal (CIO) cladded an optical fiber was obtained. Structural properties characterized by optical and scanning electron microscopy (SEM) and unique transmission spectra with photonic band gaps reveal the high quality of the silica CIOs, which can be used as fiber Bragg grating for optical communications.
Gel-Electrophoresis and Diffusion of Ring-Shaped DNA
Alon, U; Alon, Uri; Mukamel, David
A model for the motion of ring-shaped DNA in a gel is introduced and studied by numerical simulations and a mean-field approximation. The ring motion is mediated by finger-shaped loops (hernias) that move in an amoeba-like fashion around the gel obstructions. This constitutes an extension of previous reptation tube treatments. It is shown that tension is essential for describing the dynamics in the presence of hernias. It is included in the model as long range interactions over stretched DNA regions. The mobility of ring-shaped DNA is found to saturate much as in the well-studied case of linear DNA. Experiments in polymer gels, however, show that the mobility drops exponentially with the DNA ring size. This is commonly attributed to dangling-ends in the gel that can impale the ring. The predictions of the present model are expected to apply to artificial 2D obstacle arrays (W.D. Volkmuth, R.H. Austin, Nature 358,600 (1992)) which have no dangling-ends. In the zero-field case an exact solution of the model ste...
Gel electrophoresis of linear and star-branched DNA
Lau, Henry W.; Archer, Lynden A.
The electrophoretic mobility of double-stranded DNA in polyacrylamide gel is investigated using an activated hopping model for the transport of a charged object within a heterogeneous medium. The model is premised upon a representation of the DNA path through the gel matrix as a series of traps with alternating large and small cross sections. Calculations of the trap dimensions from gel data show that the path imposes varying degrees of confinement upon migrating analytes, which retard their forward motion in a size-dependent manner. An expression derived for DNA mobility is shown to provide accurate predictions for the dynamics of linear DNA (67-622 bp) in gels of multiple concentrations. For star-branched DNA, the incorporation within the model of a length scale previously proposed to account for analyte architecture [Yuan , Anal. Chem.ANCHAM0003-270010.1021/ac060414w 78, 6179 (2006)] leads to mobility predictions that compare well with experimental results for a wide range of DNA shapes and molecular weights.
Directory of Open Access Journals (Sweden)
Shivani Salil Desai
Full Text Available Chlorhexidine has bacteriocidal and bacteriostatic properties also it is used to reduce oral bacteria and dental plaque. Chlorhexidine gluconate present in gel formulations possesses antibacterial activity towards the organisms present in the dental plaque. Hence, it is a new alternative and cheaper formulation for the treatment of Periodontitis.
Gel electrophoresis of linear and star-branched DNA.
Lau, Henry W; Archer, Lynden A
The electrophoretic mobility of double-stranded DNA in polyacrylamide gel is investigated using an activated hopping model for the transport of a charged object within a heterogeneous medium. The model is premised upon a representation of the DNA path through the gel matrix as a series of traps with alternating large and small cross sections. Calculations of the trap dimensions from gel data show that the path imposes varying degrees of confinement upon migrating analytes, which retard their forward motion in a size-dependent manner. An expression derived for DNA mobility is shown to provide accurate predictions for the dynamics of linear DNA (67-622 bp) in gels of multiple concentrations. For star-branched DNA, the incorporation within the model of a length scale previously proposed to account for analyte architecture [Yuan et al., Anal. Chem. 78, 6179 (2006)] leads to mobility predictions that compare well with experimental results for a wide range of DNA shapes and molecular weights. PMID:22304125
In this study, the effectiveness of TiO2 nanoparticles in arsenic adsorption was examined. TiO2 particles (LS) were synthesized via sol-gel techniques and characterized for their crystallinity, surface area and pore volume. Batch adsorption studies were perf...
Purification of Peptide Components including Melittin from Bee Venom using gel filtration chromatography and propionic acid/urea polyacrylamide gel electrophoresis
Directory of Open Access Journals (Sweden)
Young Chon Choi
Full Text Available Objectives : This study was conducted to carry out Purification of Melittin and other peptide components from Bee Venom using gel filtration chromatography and propionic acid/urea polyacrylamide gel electrophoresis Methods : Melittin and other peptide components were separated from bee venom by using gel filtration chromatography on Sephadex G-50 column in 0.05M ammonium acetate buffer. Results : Melittin and other peptide components were separated from bee venom by using gel filtration chromatography on Sephadex G-50 column in 0.05M ammonium acetate buffer. The fractions obtained from gel filtration chromatography was analyzed by using SDS-PAGE and propionic acid/urea polyacrylamide gel electrophoresis. The melittin obtained from the gel filtration contained residual amount of phospholipase A2 and a protein with molecular weight of 6,000. The contaminating proteins were removed by the second gel filtration chromatography. Conclusion : Gel filtration chromatography and propionic acid/urea polyacrylamide gel electrophoresis are useful to separate peptide components including melittin from bee venom.
78 FR 14540 - Cyromazine, Silica Silicates (Silica Dioxide and Silica Gel), Glufosinate Ammonium, Dioctyl...
...Silica Dioxide and Silica Gel), Glufosinate Ammonium, Dioctyl Sodium Sulfosuccinate...silica dioxide and silica gel), glufosinate ammonium, dioctyl sodium sulfosuccinate...for cyromazine, silica silicates, glufosinate ammonium, DSS, and UDA to...
Dynamics of Surfactants Spreading on Gel-like Materials: Cracking and Pattern Formation
Spandagos, Constantine; Matar, Omar
We study the dynamics of surfactants spreading on gels, paying particular attention to the pattern formation accompanying the flow. The latter results from gel-cracking, promoted by Marangoni stresses, and resemble starbursts.
Fabrication of the Fine-patterns of YBCO Superconducting Thin Film by Sol-Gel Process
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ZHANG Huang-Li,ZHAO Gao-Yang,PENG Hai-Jun
Full Text Available Using methanol as solvent, cupric acetate, yttrium acetate and barium acetate as starting materials, and diethylenetriamine, trifluoroacetic acid, acrylic acid(AA as chemical additives, the photosensitive YBCO sols and gel films were fabricated by the sol-gel method. The UV absorption peak of the sols and gel films is located at about 250nm, which corresponds to the cuprate complex. The intensity of the absorption peak for the gel films gradually decreases under the UV light irradiation, and the solubility of gel films in some organic solvent as methanol is changed, showing the photosensitivity of the gel films. Utilizing the photosensitivity, the YBCO gel films are irradiated by UV light through a pattern mask and leached by methanol. Thus the fine patterning of YBCO gel film is prepared. After heat treatment, the fine patterning of YBCO film with highly Ş«c-axis oriented structure and superconducting transition temperature (TC of 92K can be obtained.
77 FR 26556 - Determination of Regulatory Review Period for Purposes of Patent Extension; EQUIDONE GEL
...as specified in 35 U.S.C. 156(g)(4)(B). FDA approved for marketing the animal drug product EQUIDONE GEL (domperidone). EQUIDONE GEL is indicated for prevention of fescue toxicosis in periparturient mares. Subsequent to this...
Sol-gel materials for optofluidics - process and applications
DEFF Research Database (Denmark)
Mikkelsen, Morten Bo Lindholm
This Ph.D. thesis is concerned with the use of sol-gel materials in optofluidic applications and the physics of DNA molecules in nanoconfinement. The bottom-up formation of solid material, which is provided by the sol-gel process, enables control of the chemical composition and porosity of the material. At early stages of gelation, thin gel coatings can be structured by nanoimprint lithography, and purely inorganic silica materials can be obtained by subsequent thermal annealing. The sol-gel process thus constitutes a unique method for nanofabrication of silica materials of special properties. In this work, sol-gel silica is introduced as a new material class for the fabrication of lab-on-a-chip devices for DNA analysis. An imprint process with a rigid, non-permeable stamp was developed, which enabled fabrication of micro- and nanofluidic silica channels in a single process step without use of any high-vacuum techniques. Sealing of the channels was performed by fusion bonding of a glass cover slipto the imprinted surface, and the applicability of the device was demonstrated by sizing experiments on DNA molecules confined in the imprinted nanochannels. In addition, in a fused silica device, the dynamics of linear and circular DNA molecules was studied under pressure driven flow in a slit channel with arrays of transverse nanogrooves. In the nanogroove geometry, transport occurs through two states of propagation: a slow, stepwise groove-to-groove translation called the 'sidewinder' and a fast, continuous tumbling across the grooves called the 'tumbleweed'. Dynamical transitions between the two states cause DNA molecules to exhibit both size- and topology-dependent velocities that may be utilized for separation. By templating the porosity of sol-gel silica with sub-wavelength latex particles, tuning of the effective refractive index of the material was enabled. Using nanoimprint lithography, a diffraction grating with refractive index of 1.33 was fabricated. This low-index grating was used to demonstrate reconfigurability of an optically functional surface topography by electrophoretic actuation of charged latex nanoparticles. Preliminary results showed 22 dB modulation of the intensity of the first diffraction order. Sol-gel material was also used as a permeable solid matrix for immobilization of analyte-sensitive dye molecules, thus constituting a sensor material for use in reagentbased optical sensing systems. Using the principle of hemiwicking, a method that enables deposition of the liquid sensor material in a homogeneous layer on a well-defined region of a surface was developed. The method simplifies the fabrication of optical sensors integrated in disposable lab ware.