text:
Some researches about various functionalities on textile materials treated with in situ sol‐gel method and sols with nanoparticles.
\r\n\t",isbn:null,printIsbn:null,doi:null,price:0,slug:null,numberOfPages:0,isOpenForSubmission:!1,hash:"429d24d493e64821ae08df0a71d33e37",bookSignature:"Prof. Maguid H.M. Hassan",publishedDate:null,coverURL:"https://cdn.intechopen.com/books/images_new/8822.jpg",keywords:"Fuzzy Inference Systems, Neural Networks, Heritage Structures, Heritage Conservation, Component Reliability, System Reliability, Redundancy, Probabilistic Approach, Intelligent Algorithms, Uncertainty , Sustainability, Sustainable Design",numberOfDownloads:144,numberOfWosCitations:0,numberOfCrossrefCitations:0,numberOfDimensionsCitations:0,numberOfTotalCitations:0,isAvailableForWebshopOrdering:!0,dateEndFirstStepPublish:"September 24th 2018",dateEndSecondStepPublish:"October 15th 2018",dateEndThirdStepPublish:"December 14th 2018",dateEndFourthStepPublish:"March 4th 2019",dateEndFifthStepPublish:"May 3rd 2019",remainingDaysToSecondStep:"4 months",secondStepPassed:!0,currentStepOfPublishingProcess:4,editedByType:null,editors:[{id:"141308",title:"Prof.",name:"Maguid",middleName:"H.M.",surname:"Hassan",slug:"maguid-hassan",fullName:"Maguid Hassan",profilePictureURL:"https://mts.intechopen.com/storage/users/141308/images/system/141308.jpeg",biography:"Prof. Hassan earned his B.Sc. in Structural Engineering in 1983 from Ain-Shams University, followed by M.Sc. in 1988 from the same school in Structural Dynamics. During the first five years of his career he practiced engineering across several capacities in structural steel and reinforced concrete design and construction. \nProf. Hassan then joined the University of Maryland at College Park, USA, in 1988 as a teaching assistant studying towards his PhD. As a teaching assistant, Prof. Hassan taught several engineering courses in the US at the 200 and 400 levels. He worked on several research projects during his doctoral studies. He developed a real time safety fuzzy controller for structures during their construction stage. Prof. Hassan earned his Ph.D. in 1992 from the University of Maryland at College Park, USA, in Structural Reliability. He then joined one of the private higher education institutions, in Egypt, where he helped develop the curriculum of the civil engineering department. Prof. Hassan was awarded a Fulbright teaching/research grant in 2004 where he taught structural engineering courses at the University of Maryland at College Park for one academic year and conducted his research. Prof. Hassan joined the BUE in 2006 to establish the Civil Engineering Department. During this period, he was involved in the establishment of the Civil Engineering Department, through the development of an up-to-date curriculum. As the founding Head, he led the efforts in validating the program by a UK partner University, according to the QAA regulations which was successfully achieved in August 2007. \nProf. Hassan was appointed as an Associate Dean for Research and Community Engagement in 2013 then as the Dean of Engineering in 2014.",institutionString:"The British University in Egypt (BUE)",position:"Prof./Dean of Engineering",outsideEditionCount:0,totalCites:0,totalAuthoredChapters:"1",totalChapterViews:"0",totalEditedBooks:"0",institution:{name:"British University in Egypt (BUE)",institutionURL:null,country:null}}],coeditorOne:null,coeditorTwo:null,coeditorThree:null,coeditorFour:null,coeditorFive:null,topics:[{id:"24",title:"Technology",slug:"technology"}],chapters:[{id:"65199",title:"Nanotechnology and Development of Strain Sensor for Damage Detection",slug:"nanotechnology-and-development-of-strain-sensor-for-damage-detection",totalDownloads:39,totalCrossrefCites:0,authors:[null]},{id:"64878",title:"Application of a Frequency-Based Detection Method for Evaluating Damaged Concrete Sleepers",slug:"application-of-a-frequency-based-detection-method-for-evaluating-damaged-concrete-sleepers",totalDownloads:42,totalCrossrefCites:0,authors:[null]},{id:"65037",title:"Monitoring of Critical Metallic Assets in Oil and Gas Industry Using Ultrasonic Guided Waves",slug:"monitoring-of-critical-metallic-assets-in-oil-and-gas-industry-using-ultrasonic-guided-waves",totalDownloads:0,totalCrossrefCites:0,authors:[null]},{id:"65016",title:"The Importance of Emissivity on Monitoring and Conservation of Wooden Structures Using Infrared Thermography",slug:"the-importance-of-emissivity-on-monitoring-and-conservation-of-wooden-structures-using-infrared-ther",totalDownloads:63,totalCrossrefCites:0,authors:[null]}],productType:{id:"1",title:"Edited Volume",chapterContentType:"chapter",authoredCaption:"Edited by"},personalPublishingAssistant:{id:"270941",firstName:"Sandra",lastName:"Maljavac",middleName:null,title:"Ms.",imageUrl:"https://mts.intechopen.com/storage/users/270941/images/7824_n.jpg",email:"email@example.com",biography:"As an Author Service Manager my responsibilities include monitoring and facilitating all publishing activities for authors and editors. From chapter submission and review, to approval and revision, copyediting and design, until final publication, I work closely with authors and editors to ensure a simple and easy publishing process. I maintain constant and effective communication with authors, editors and reviewers, which allows for a level of personal support that enables contributors to fully commit and concentrate on the chapters they are writing, editing, or reviewing. I assist authors in the preparation of their full chapter submissions and track important deadlines and ensure they are met. I help to coordinate internal processes such as linguistic review, and monitor the technical aspects of the process. As an ASM I am also involved in the acquisition of editors. Whether that be identifying an exceptional author and proposing an editorship collaboration, or contacting researchers who would like the opportunity to work with IntechOpen, I establish and help manage author and editor acquisition and contact."}},relatedBooks:[{type:"book",id:"9336",title:"Technology, Science and Culture",subtitle:"A Global Vision",isOpenForSubmission:!1,hash:"e1895103eeec238cda200b75d6e143c8",slug:"technology-science-and-culture-a-global-vision",bookSignature:"Sergio Picazo-Vela and Luis Ricardo Hernández",coverURL:"https://cdn.intechopen.com/books/images_new/9336.jpg",editedByType:"Edited by",editors:[{id:"293960",title:"Dr.",name:"Sergio",surname:"Picazo-Vela",slug:"sergio-picazo-vela",fullName:"Sergio Picazo-Vela"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"6826",title:"The Use of Technology in Sport",subtitle:"Emerging Challenges",isOpenForSubmission:!1,hash:"f17a3f9401ebfd1c9957c1b8f21c245b",slug:"the-use-of-technology-in-sport-emerging-challenges",bookSignature:"Daniel Almeida Marinho and Henrique Pereira Neiva",coverURL:"https://cdn.intechopen.com/books/images_new/6826.jpg",editedByType:"Edited by",editors:[{id:"177359",title:"Dr.",name:"Daniel Almeida",surname:"Marinho",slug:"daniel-almeida-marinho",fullName:"Daniel Almeida Marinho"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"6516",title:"Metrology",subtitle:null,isOpenForSubmission:!1,hash:"09e6966a3d9fadcc90b1b723e30d81ca",slug:"metrology",bookSignature:"Anil",coverURL:"https://cdn.intechopen.com/books/images_new/6516.jpg",editedByType:"Edited by",editors:[{id:"190673",title:"Associate Prof.",name:"Anil",surname:"Akdogan",slug:"anil-akdogan",fullName:"Anil Akdogan"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"8354",title:"Flexible Electronic Paper Based Displays",subtitle:null,isOpenForSubmission:!0,hash:"6077f645585a2b115920398982d46178",slug:null,bookSignature:"",coverURL:"https://cdn.intechopen.com/books/images_new/8354.jpg",editedByType:null,editors:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"8362",title:"Time Series Analysis",subtitle:null,isOpenForSubmission:!1,hash:"7e98dd03d921c19cc2324e91845d5160",slug:null,bookSignature:"Dr. Chun-Kit Ngan",coverURL:"https://cdn.intechopen.com/books/images_new/8362.jpg",editedByType:null,editors:[{id:"227503",title:"Dr.",name:"Chun-Kit",surname:"Ngan",slug:"chun-kit-ngan",fullName:"Chun-Kit Ngan"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"8677",title:"Global Positioning System",subtitle:null,isOpenForSubmission:!0,hash:"32ef335e42ace85473f4e4f7ccac5805",slug:null,bookSignature:"Dr. Rustam B. Rustamov and Dr. Sefer Kurnaz",coverURL:"https://cdn.intechopen.com/books/images_new/8677.jpg",editedByType:null,editors:[{id:"59174",title:"Dr.",name:"Rustam B.",surname:"Rustamov",slug:"rustam-b.-rustamov",fullName:"Rustam B. Rustamov"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"8724",title:"Gas Sensors",subtitle:null,isOpenForSubmission:!0,hash:"bc4be4b954b559709aaace45f70adcd0",slug:null,bookSignature:"Dr. Sher Bahadar Khan, Dr. Abdullah M. Asiri and Dr. Kalsoom Akhtar",coverURL:"https://cdn.intechopen.com/books/images_new/8724.jpg",editedByType:null,editors:[{id:"245468",title:"Dr.",name:"Sher Bahadar",surname:"Khan",slug:"sher-bahadar-khan",fullName:"Sher Bahadar Khan"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"9175",title:"Electronic Test Equipment",subtitle:null,isOpenForSubmission:!0,hash:"f8af91915a5ce9b7527de5720aa8f02f",slug:null,bookSignature:"",coverURL:"https://cdn.intechopen.com/books/images_new/9175.jpg",editedByType:null,editors:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"7648",title:"Sport Technology",subtitle:null,isOpenForSubmission:!0,hash:"f07d63b59d525116ce6452304c5f9926",slug:null,bookSignature:"Dr. Christopher P. Johnson",coverURL:"https://cdn.intechopen.com/books/images_new/7648.jpg",editedByType:null,editors:[{id:"289721",title:"Dr.",name:"Christopher P.",surname:"Johnson",slug:"christopher-p.-johnson",fullName:"Christopher P. Johnson"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"7704",title:"Assistive Technologies",subtitle:null,isOpenForSubmission:!1,hash:"6fc608c535075ca3391a14d41b02276e",slug:null,bookSignature:"",coverURL:"https://cdn.intechopen.com/books/images_new/7704.jpg",editedByType:null,editors:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}}]},chapter:{item:{type:"chapter",id:"54300",title:"Sol-Gel Applications in Textile Finishing Processes",doi:"10.5772/67686",slug:"sol-gel-applications-in-textile-finishing-processes",body:'\n
Functional properties can be given to textile materials by textile finishing processes. The use of sol‐gel technology in textile finishing processes has taken very much attention in the last decades. Sol‐gel technology has advantages such as less chemical usage, low‐temperature treatment, easy application and treatment facilities in textile mills, and no requirement for special equipment [1, 2].\n
Moreover, sol‐gel technology makes enabling multifunctional properties in one step which is not possible by conventional textile finishing methods because of incompatibility of chemical materials. In conventional textile finishing methods, the treatments have separately been applied in several steps to obtain functional properties and these multistep processes increase the costs of the textile mills. Therefore, enabling multifunctional properties in one step is a challenging process to overcome in terms of decreasing water and energy consumption and costs. On the other hand, besides the various advantages, sol‐gel technology has a disadvantage of high costs of precursor materials used in sol‐gel technology. In sol‐gel technology, metal alkoxides and metallic salts have been used as precursors and by the catalytic effect of an acid or alkali, hydrolysis and condensation reactions occur [1, 2]. The reactions of precursor materials with textile surfaces are given in Figure 1. Nanosols can be applied to fabric by pad‐dry‐cure process. Application steps of nanosols to textiles are illustrated in Figure 2.\n
By sol‐gel technology, various functional properties can be given to textile materials or some properties that already exist can be developed in one or more steps. The use of sol‐gel technology in textile industry for flame retardancy, antimosquito [3], water or oil repellency [4], antibacterial activity [5], antiwrinkle, anticrease, durable press or easy‐care effect [6], ultraviolet (UV) protection, self‐cleaning or soil repellency, photocatalytic activity [7], development in fastness behavior, abrasion resistance, tensile and thermal properties, and in microencapsulation process have been studied in detail. In Figure 3, the application areas of sol‐gel technology in textile finishing processes have been demonstrated. The aim of this review is to introduce the usage possibilities of sol‐gel technology in textile applications.
There has been a significant importance to improve flame retardancy properties of textile materials for hindering the fire damages because they are primary combustion sources in a fire. Chloride‐, bromide‐, phosphorus‐, antimony‐, and boron‐based materials have been used for textile materials to give flame‐retardant activity. In addition, the combination of these chemical materials (e.g., antimony‐halogen or phosphorus‐nitrogen) can also be used due to their synergistic effect. By sol‐gel method, high chemical concentration (nearly 300–500 g/l) used in conventional methods can be significantly decreased or by the use of chemical materials without halogen, ecological, and economical flame‐retardant activity can be obtained. Alongi and Malucelli [8] reported the detailed review of flame retardancy treatment of cotton fabrics by sol‐gel process until 2015.\n
Grancaric et al. [9] studied the flame retardancy properties of cotton fabric by using diethylphosphatoethyltriethoxysilane (DPTES) as a sol‐gel precursor together with monoethanolamine (MEA) as a neutralizer for acidic conditions of DPTES with or without the addition of tetraethoxysilane (TEOS) and 3‐glycidoxypropyltriethoxysilane (GPTES) to increase the durability of finishing process. Their results showed that the cotton samples were in self‐extinguished classification and had the LOI (limited oxygen index) value of 29. It was observed that the amount of residue of treated fabrics at Tmax compared with that of untreated fabric increased from 37.5 to 60% and the total heat release (THR) of treated fabrics with respect to untreated fabric decreased from 12 to 4.2 kJ/g. Thermal shielding effect of silica phases and char‐forming by synergistic effect of phosphorous and nitrogen were attributed to be the causes of flame retardancy and thermal behavior of cotton samples. However, the LOI values of fabric samples reduced from 29 to 21 after one washing process [9].\n
Boukhriss et al. [11] investigated the flame retardancy and water repellency properties of cotton fabric treated with sols containing 1‐methylimidazolium chloride propyltriethoxysilane (MCPTS) and 1‐pyridinium chloride propyltriethoxysilane (PCPTS) salts synthesized. The results indicated that their flame retardancy and water repellency properties improved. Water uptake values with dip test with regard to untreated fabric decreased from 340 to 50%. The weight of residue of treated fabric samples regarding untreated fabric increased from 1 to 93% which is higher than the test results (48%) reported by Alongi et al. [10]. The fabric samples lost their flame retardancy properties after three washing process and entirely burnt [11].\n
Kappes et al. [12] coated the cotton, PET fabric, and polyester/cotton blends with (3‐trimethoxysilylpropyl)diethylenetriamine (TRIAMO) by sol‐gel process. Then, coated and uncoated fabrics were treated with phenylphosphonic acid. Hole formation, flame spread to upper or side edges, and burning time after flame application of samples were evaluated by surface and edge‐ignition tests according to EN ISO 15025. The two‐step treatment of cotton and blend fabrics improved their flame retardancy properties and burning and hole formation after flame treatment of the samples were not observed while cotton fabrics treated with only sol‐gel and only phenylphosphonic acid treatment showed burning and hole formation. Polyester fabric samples displayed hole formation and burning after flame treatment, but flame did not reach the upper or side edges for the fabric samples treated with two‐step process and only phenylphosphonic acid due to recede of fabric from flame. Sol‐gel treatment gave rise to prolong burning time after flame treatment and to prevent fabrics receding from flame that is known to be undesired. Peak heat release rate (pHRR) of all fabric samples treated with two‐ and one‐step process decreased compared with untreated fabric. The total heat evolved (THE) of polyester fabric slightly increased, while these of cotton and blend fabrics slightly decreased [12].\n
Zhang et al. [13] treated silk fabric to give flame retardancy by using TEOS and boric acid by means of sol‐gel process. They used 1,2,3,4‐butanetetracarboxylic acid (BTCA) as crosslinking agent to improve durability of flame retardancy properties of the fabric samples. The results showed that LOI values of silk fabric containing P, N, or S with inherent difficult flammability increased from 25.3 to 32.3% by treatment with BTCA solution and then nanosol‐containing boric acid as a flame‐retardant agent. They found that the flame retardancy of silk fabric was durable to even 30 washing cycles. They demonstrated that the pHRR, temperature at pHRR, the total heat release (THR), weight loss, and the density of released smoke of the fabric samples compared to control fabric decreased as indicating low flammability [13].\n
Šehić et al. [14] investigated the synergistic effect of the presence of Si‐ and P‐ on polyamide 6 fabric surface treated by sol‐gel process using 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO)‐modified vinyltriethoxysilane (VTS) and tetraethoxysilane (TEOS) as precursors. The increase in the percentage of residue at Tmax1 and the decrease in Tonset were attributed to promoting char formation. The heat release capacity (HRC), pHRR, and THR of fabric samples were found to be reduced. Ignition of cotton under burning samples, after‐flame, and after‐glow times were analyzed by vertical flame‐spread test, DIN 53906. The combination of Si and P and the presence of only Si contributed to no dripping, no ignition of cotton substrate under burning sample, longer after‐flame time, and no after‐glow. Synergistic effectiveness values of samples proved the synergistic activity of Si and P in condensed phase. Figure 4 shows the combustion cycle of polymer [15].\n
Deh et al. [16] studied the synergistic effect of N and Si added to phosphorous compounds on flame retardancy of cotton fabric treated by phosphorylation using phosphoric acid and urea and then by sol‐gel process using TEOS as a precursor. They found that the cotton fabrics treated by phosphorylation and sol‐gel process had high LOI values (>25%) with durability to 10 washing processes. The presence of Si together with N and P on cotton fabric contributed to developing the formation of char acting as a thermal‐insulating barrier and to decrease the number of byproducts which are not promoting the dehydration process, is requested flame retardant activity. Dehydration of cotton at low temperature was observed to support char formation and synergistic effect reduced the formation of levoglucosan whose decomposition generates flammable gases and product after pyrolysis. Figure 5 illustrates the thermal degradation of cotton with heating [16].\n
Liu et al. [17] synthesized di‐(triethoxysilylpropyl) phenylphosphamide (PPD‐PTES) by reaction of 3‐aminopropyl triethoxysilane (APTES) and phenylphosphonic dichloride (PPDC) and then treated cotton fabric with PPD‐PTES for 5, 10, 20, and 30 min of immersion times by sol‐gel process. As a result of vertical burning test, the fabric treated with PPD‐PTES containing P‐, Si‐ and N‐elements self‐extinguished as ignition source was found to be withdrawn and minimum char area left was observed on the fabric treated with 30 min of immersion time. As long as immersion times were increased, char residue increased while Tmax, pHRR, and THR decreased. Nevertheless, they found that the absorbance intensity of CO2, which is one of the non‐flammable gases, did not significantly change in treated fabrics compared to that of untreated fabric while their intensity of C=O and C‐O‐C groups, which are found in flammable gases and compounds, decreased by virtue of Fourier transform infrared spectroscopy(FTIR) analysis [17].\n
Ren et al. [18] investigated the flame retardancy properties of polyacrylonitrile (PAN) fabric treated by one‐step sol‐gel process using TEOS and polyphosphoric acid (PPA). The increase at their LOI and char residue to, respectively, 30.1 and 69.48% and the decrease at their THR, pHRR, the fire growth rate index (FIGRA), average mass loss rate (aMLR), the peak of smoke production rate (pSPR), and total smoke production (TSP) as a result of cone calorimetry test [18] were determined.\n
Aksit et al. [19] proved the synergistic effect of Si, P, and N on flame‐retardant cotton fabrics treated with (3‐aminopropyl) triethoxysilane as N‐ and Si‐source, (3‐glycidyloxypropyl) trimethoxysilane as Si‐source, and guanidine phosphate as P‐source by sol‐gel technique. They determined that the fabric samples had 45.7% LOI values [19].
Hydrophobic effect can be given to textile materials by decreasing the surface tension of textile material against the liquid [1]. In conventional methods, fluorocarbon components have been used for this purpose. However, sol‐gel technology as an alternative method has also been studied because of the harmful effects of fluorocarbon components to the environment. Many researches have been conducted about the use of modified silane precursors by sol‐gel technology in order to enable hydrophobic effect on textile materials. It was aimed to gain surface roughness together with creating low‐surface energy on substrate surface based on the theory of Wenzel or Cassie and Baxter [20–22] in order to produce superhydrophobic materials in many researches. Moreover, the durability to abrasion, washing and UV exposure, and so on of their superhydrophobic properties for especially outdoor materials were maintained as a significant challenge. Schematic illustration of hydrophilicity‐hydrophobicity properties of substrate as contact angles is given in Figure 6.\n
Zhao et al. [24] treated the cotton, cotton/polyester, and polyester fabric by using nanosol containing silica nanoparticles, (3‐aminopropyl) triethoxysilane (APTES, 99%), and hexadecyltrimethoxysilane (HDTMS) by spray process. They achieved the production of fabrics with contact angle (CA) >150° and hysteresis <10° required to gain superhydrophobic properties to fabric. The increasing amount of HDMS or silica nanoparticles led to higher contact angle and lower‐surface energy than that of uncoated fabrics. Surface roughness values measured by atomic force microscopy (AFM) were found to increase for cotton and cotton/polyester fabric compared to uncoated fabrics. The cotton and polyester fabric did not lose their superhydrophobic properties after five washing processes. In addition, the fabrics kept their hydrophobic properties even after 600 abrasion cycles [24].\n
Xue et al. [25] coated polyester fabric with polymer paste containing silica nanoparticles and polydimethylsiloxane (PDMS) by spread coating method and then posttreated by nanosols containing TEOS and cetyltrimethoxysilane (CTMS). They determined the hydrophobic properties (CA >90°) of fabrics coated with PDMS‐silica nanoparticles and superhydrophobic properties (162.5 of CA, 5.4 of sliding angle (SA)) of fabric posttreated by TEOS and CTMS. From the study, it was observed that water pressure resistance properties (38.6 kPa) of fabrics developed, their CAs a little decreased, and their SAs slightly increased as the number of coatings increased. Their contact angles and water resistance properties did not demonstrate significant change after basic and acidic treatment with different pH values or after UV‐light exposure. However, water pressure resistance of fabrics decreased to 10 kPa after abrasion test for even 10 cycles because of the insufficient binding force between coating layer and fabric [25].\n
Hao et al. [26] investigated polymer nanocomposites (PNs) synthesized by in situ sol‐gel process to achieve multifunctional properties of cotton fabrics. Crosslinked polysiloxane (CLPS) with aminopropyltriethoxysilane (APTES) and then obtained APTES‐CLPS with silica sols (CLPS‐SiO2) were treated by in situ sol‐gel process. The cotton fabric was immersed in APTES‐CLPS or CLPS‐SiO2 solutions in ethyl acetate and padded, dried, and cured. They concluded that the fabric samples treated with CLPS‐SiO2 had better thermal stability with lower weight loss in TGA analysis, higher the root‐mean‐square roughness (4.528 nm) than that treated with APTES‐CLPS due to the presence of silica nanoparticles. The contact angles of the fabric reached 158° and they did not lose their superhydrophobic properties until 10 washing cycles [26].\n
Zhang et al. [27] produced an oligomer of hexadecyltriethoxysilane (HD‐oligomer) (HDTES) and HDTES‐modified silica nanoparticles (HD‐silica) by Stöber method based on sol‐gel process. In the second step, HD‐silica/HD‐oligomer nanocomposites were prepared by adding HDTES, TEOS, ethanol, water, and ammonia to HD‐silica and HD‐oligomer. Subsequently, wool fabrics were immersed in nanocomposite solution in toluene and triethylamine as catalyst and exposed to ultrasonication to produce superhydrophobic wool fabric with excellent abrasion resistance, excellent chemical and environmental stability, excellent mechanical resistance for adhesion of double side tape and scratching with a scalpel, and good washing durability for 10 washing cycles [27].\n
Vasiljević et al. [28] studied the improvement of water repellency properties of the cotton fabric by first treating with oxygen plasma and then with 1H,1H,2H,2H‐perfluorooctyltriethoxysilane (SiF) in ethanol by sol‐gel process. The fabrics pretreated by plasma for 20 s at an operating current of 0.3 A resulted in nearly 150° of contact angle and 24° of sliding angle [28].\n
Przybylak et al. [29] previously impregnated cotton fabric with octaanion solution synthesized by using TEOS, tetramethylammonium hydroxide, methanol, and water and squeezed, dried, and subsequently impregnated with bifunctional silsesquioxanes containing octafluoropentyloxypropyl groups and trimethoxysilylethyl synthesized. Squeezed, dried, and cured fabric samples were found to have superhydrophobic properties with 151° of contact angle and durability against 10 washing cycles [29].\n
Xue et al. observed that the fabrics treated with nanosols containing tetrabutyl titanate and then with 1H, 1H, 2H, 2H‐perfluorodecyltrichlorosilane in toluene and/or stearic acid in acetone and cured at 110°C for 1 h had superhydrophobic properties and good UV‐protection properties [30].\n
Onar and Mete [31] investigated water repellency properties of the cotton fabric treated with two‐step process as surface roughening with ZnO, Al2O3, TiO2, and ZrO2 nanoparticles and hydrophobic modification with long‐chain alkyl silanes (hexadecyltrimethoxy silane). From the study, it was observed that the cotton fabric treated with Al2O3 nanoparticles and HDMS had superhydrophobic properties and all fabric samples treated with nanoparticles and HDMS maintained their hydrophobic properties after washing process [31].\n
Onar et al. [32] purposed to achieve the production of water‐repellent cotton fabric by sol‐gel process using tridecafluorooctyltriethoxysilane (FTES), hexadecyltrimethoxysilane (HDTMS), glycidyloxypropyltriethoxysilane (GLYE), phenyltriethoxysilane (FES), vinyltrimethoxysilane (VTEO), 3‐aminopropyl trimethoxysilane (AMMO), titanium (IV) isopropoxide (TIPT), and zirconium (IV) acetylacetonate (ZrAc) as precursors. They found that the treatment with HDTMS under acidic and alkaline conditions or FTES under alkaline conditions led to provide superhydrophobicity on cotton fabric. The fabric samples treated with FES, VTEO, TIPT, and GLYE precursors lost their hydrophobic properties after washing process, while the fabrics treated with HDMS, FTES, AMMO, and ZrAc precursors preserved the hydrophobic properties after washing process [32].\n
Colleoni et al. [33] treated the cotton and polyester fabric with octyltriethoxysilane (OTES) together with melamine‐based crosslinking agent. They revealed that the cotton and polyester fabrics had good hydrophobic properties with, respectively, 130° and 150° of contact angle values [33].\n
Gao et al. [34] researched the hydrophobic properties of the cotton and polyester fabric treated with TEOS and then HDTMS by sol‐gel process (Figure 7). The process imparted highly hydrophobic properties to the cotton (155° CA) and polyester fabric (143° CA) with durability till 30 washing processes and a slight reduction of their tensile strength (<10%) [34].\n
Teli and Annaldewar [35] studied the water repellency and UV‐protection properties of cotton fabric dip coated with silica nanoparticles prepared by sol‐gel process and subsequently impregnated with zinc nitrate hexahydrate in hexamine and then hydrophobically modified with ethanolic sodium stearate solution. As a result of that, the fabric samples imparted excellent UV protection with +50 UPF and superhydrophobic properties. The fabric samples had still excellent UV protection and hydrophobic properties after 10 washing cycles [35].\n
de Ferri et al. [36] coated the silk fabric with nanosols composed of 3‐glycidoxypropyltrimethoxysilane (GLYMO) and DynF8815 with acid catalyst by sol‐gel process. The treatment caused the high abrasion resistance to 8500 cycle, high contact angle (nearly 123° CA) to four oils, and hydrophobic properties with 148° of contact angle. The washing durability of oil and water repellency of the fabric samples was also analyzed. It was observed that the fabric had still hydrophobic (130° CA) and oleophobic properties (100° of CA) after, respectively, 15 washing and 5 washing cycles [36].\n
Vasiljević et al. [37] aimed to produce highly oleophobic and superhydrophobic cotton fabric by three‐step sol‐gel process. The first step was the treatment of cotton fabric with silica nanoparticles with different average particle sizes (50 ± 15, 230 ± 20, and 780 ± 30 nm) prepared according to Stöber method based on sol‐gel process; the second step was the application of the in situ growth of polysiloxane layer on cotton fabric in basic TEOS solution, and the third step was the padding with a fluoroalkyl functional water‐borne oligosiloxane (FAS, Dynasylan F 8815). They obtained fabric samples with low sliding angle (2°), high oleophobicity (6), and superhydrophobicity durable to 10 washing cycles [37].
Long‐time exposure to UV light may result in early skin aging, allergy, sun burns, or even skin cancer in especially fair‐skinned human. Various chemical agents such as benzophenone derivatives, ortho‐hydroxy phenyl, and diphenyl triazine derivatives as organic UV absorbers and TiO2 and ZnO particles as inorganic UV absorbers have been used [38]. Alternatively, UV protection can be obtained by sol‐gel method with generally TiO2 and ZnO nanoparticles incorporated to textile materials. TiO2 nanoparticles provide self‐cleaning as well as UV protection by means of photocatalytic reaction. Anatase phase of TiO2 nanoparticles, which is one of three phases of TiO2 (anatase, brookite, and rutile), has photocatalytic activity. The formation of anatase phase at low temperature on textile material coated with titania nanosols is a big challenge because textile materials cannot endure high temperature [39]. Researchers are investigating some solutions such as steaming process [40, 41], hydrothermal process [42], or solvothermal process [43] to produce anatase crystals at low temperature so far.\n
Photocatalytic reaction leads to the decomposition of organic and inorganic pollutants under the ultraviolet light [43]. In addition, organic components such as microorganisms in textile surfaces and dyestuff residues in textile wastewater can also be decomposed by photocatalytic effect. By this way, photocatalytic effect ensures not only UV protection and self‐cleaning but also antibacterial effect and ecological and economical wastewater treatment [43, 44]. Figure 8 illustrates the self‐cleaning properties of cotton fabric treated with titania nanosols.\n
Liu et al. [46] investigated the self‐cleaning and UV‐protection properties of raw wool fabric and Kroy‐process wool fabric (removed scales with chlorination process) treated with polycarboxylic acid such as 1,2,3,4‐butanetetracarboxylic acid (BTCA), citric acid (CA) as crosslinking agent and then nanosols prepared by using titanium (IV) butoxide (TBT) and TEOS as precursors. The self‐cleaning properties of the fabric samples were evaluated by photo‐induced decomposition test of methylene blue. Self‐cleaning properties of raw wool fabric were found to be better than that of Kroy‐process wool fabric, while UPF values of raw material (356) were lower than that of Kroy‐process wool fabric (992) [46].\n
Dhineshbabu et al. [47] studied the UV‐protection, antibacterial, and flame retardancy properties of cotton fabric treated with colloidal sols containing TEOS as precursor and polyethylene glycol (PEG) as stabilizer and TiO2 nanoparticles produced by sol‐gel process. They found that UPF values of the fabric samples were greater than 50 UPF corresponding to excellent UV protection after even 10 washing cycles. According to ASTM D1230 standard, their results showed that the total burning time and residual weight after burning of the fabric samples were higher than that of untreated fabric according to the flame test at 45° angle. Thus, their burning performance improved after the treatment and nearly 70% of this performance was preserved after 10 washing cycles. The study revealed that the fabric samples had good antibacterial activity against Staphylococcus aureus and Escherichia coli with, respectively, 18 and 15 mm diameter of inhibition zone because of the reactive oxygen species (ROS) generation mechanism of TiO2 nanoparticles [47].\n
Rilda et al. [48] previously produced TiO2‐SiO2 powder by using titanium isopropoxide and TEOS as precursors with different molar ratios, diethanol amine (DEA) as stabilizer, isopropanol as solvent, and chitosan in acetic acid as dispersing agent by sol‐gel process. The fabric samples coated with acrylic acid binder were immersed to TiO2‐SiO2 suspension containing the powder, surfactant, and isopropanol and then coated with the suspension to ensure homogeneous coating by spin‐coating machine. Falling at absorbance of methylene blue under UV irradiation for 120 min was attributed to self‐cleaning properties of fabrics treated with TiO2‐SiO2 powders with especially 1:2 molar ratios [48]. The discoloration of wine stain on cotton fabric treated with TiO2‐SiO2 colloidal solution increased exposure times under solar light simulator for 0, 4, 8, and 24 h [49].\n
Wang et al. [39] treated the cotton fabric with TiO2 acidic hydrosol prepared with titanium (IV) butoxide as precursor by dip‐pad‐steam process. Photocatalytic activity of TiO2 prepared by low‐temperature steaming process was higher than that of TiO2 dried at 150°C. They stated that the fabric samples had excellent durable self‐cleaning and UV‐protection properties. The crystallinity and photocatalytic activity of TiO2 improved with the increase of the water content in TiO2 hydrosol [39].\n
Shaban et al. [50] investigated the self‐cleaning properties of cotton fabrics coated with ZnO nanoparticles or ZnO solution containing zinc acetate dihydrate as precursor, 2‐methoxyethanol as solvent, and monoethanolamine as stabilizer by sol‐gel spin‐coating process. Their results indicated that ZnO nanoparticles had photocatalytic activity especially under UV irradiation due to their high band‐gap energy and the methyl orange dye on cotton fabrics coated with ZnO nanoparticles or ZnO solution degraded under sunlight and 200‐W lamp illumination [50].\n
Noorian et al. [51] prepared precursor solutions based on copper sulfate and/or zinc chlorite containing folic acid, NaOH, and water by in situ synthesis. They immersed the cotton fabric in the solutions, dried and washed. They stated that the combination of ZnO and Cu2O and the addition of folic acid improved the UV protection and anticrease properties of the fabric samples with, respectively, 87.31% enhanced UVP and 100.75° of crease recovery angle [51].
Antibacterial and antimicrobial activities are important for sport, outdoor, home, automotive, and medical textiles and for garments like hosiery and underwear. For antibacterial and antimicrobial textile finishing, various biocides like silver, triclosan, chitosan, quaternary ammonium salts, N‐halamines, biguanide derivatives, synthetic dyes, and peroxyacids have been applied to textile surfaces [52–58]. Sol‐gel technology as an alternative method can bring advantages like ecological treatment, less chemical use, low‐temperature processing, low toxicity to human health, protection of inherent properties of textile material, and excellent washing and usage durability in this finishing process [52, 55, 59–61].\n
Different types of sol‐gel systems are known to have antibacterial or antimicrobial effect. These systems are photoactive titania coatings with anatase modification and sol‐gel coatings with embedded colloidal metal or metal compounds like silver, silver salts, copper compounds, zinc, or biocidal quaternary ammonium salts [5, 62–65]. On the other hand, these systems have several disadvantages like high operation temperatures to produce highly photoactive thin films and the use of strong acids to keep aqueous sols in the peptized state that cause destruction on textiles. In addition, titania coatings require UV radiation to perform antimicrobial or antibacterial activity [66–69]. Because of harmful effects of strong acids and high temperatures on textiles, in recent methods, organic solvents, for example, alcohol‐based solutions that can be applied at low temperatures, were developed [5, 59, 60]. Simoncic et al. compiled the antibacterial activity of silver nanoparticles prepared by in situ method and colloidal solutions [70].\n
Poli et al. prepared zinc‐based coatings by sol‐gel method in neutral hydro‐alcoholic medium and applied on cotton fabric to obtain antibacterial activity. They reported that this method was simple, cheap, reproducible, and less harmful when compared to conventional methods [5]. Other than titania‐based sol‐gel coatings, silica‐based coatings are also under examination for antibacterial or antimicrobial effectiveness. To enable the antibacterial or antimicrobial effect, polycationic components are incorporated within the silica layer matrix and by this means positively charged polycationic components interact with negatively charged microbial cell membranes and damage their cellular functions [5, 61, 62, 63]. The use of these systems was researched in detail [5, 59–63, 67].\n
Mahltig et al. reported that the sol‐gel processing exhibited the antimicrobial activity based on controlled release, contact action, or photocatalytic activity [71].\n
Rivero and Goicoechea presented the detailed review about improving antibacterial properties of textiles by sol‐gel process [72].\n
Zhang et al. classified the application methods on cotton methods for colloidal suspensions of metal nanoparticles and precursor solutions of metal ions, respectively, titled as sol and solution to gain antimicrobial properties [52].\n
Mohamed et al. [73] prepared the colloidal solutions of silver nanoparticles (10–25 nm) synthesized by chemical reduction process using dextran as stabilizing and reducing agent and modified TEOS using ascorbic acid as scavenging agent and (3‐aminopropyl)triethoxysilane (APTEOS) by using BTCA or vinyltriethoxysilane (VTEOS) and applied it to cotton fabrics by sol‐gel process by dip coating. Silver nanoparticles modified with TEOS and VTEOS were cured with UV irradiation by means of a photoinitiator. They proved that the modified fabrics had antibacterial activity against S. aureus and E. coli with nearly 90% of bacterial reduction even after 20 washing cycles and thermo‐regulating properties [73].\n
The combination of antibacterial biopolymers with titania and silica matrix is a different method and this method is observed to give ecological advantage and possessed antibacterial activity both in the presence or absence of light. Arik and Seventekin [55] studied chitosan/titania and chitosan/silica hybrid coatings in terms of antibacterial activity. Sol‐gel method was used to prepare coating solutions and then solutions were applied to cotton fabric. From the study, hybrid coatings were found to have better antibacterial activity and washing durability than only chitosan, only titania, or only silica coatings [55].
Antiwrinkle, anticrease, durable press, or easy‐care effect has been enabled by the fixation of the crosslinking agents to textile materials. Since dimethyloldihydroxyethylene urea (DMDHEU), which was used commonly in conventional antiwrinkle finishing treatments, releases free formaldehyde that is harmful to human health and environment and causes negative effects due to the acidic catalysts on tensile properties and whiteness index of textile materials, new alternative crosslinking agents and methods have been recently researched. By means of sol‐gel technology, it is possible to enable antiwrinkle effect herewith good tensile and whiteness properties by the use of silane coupling agents [74, 75] like glycidoxy propyltrimethoxysilane as epoxy silanes, vinyltrimethoxysilane as vinyl silanes [76, 77], and tetraethoxysilane that do not release formaldehyde [78–80].\n
The main cause of the tensile strength loss and yellowing in conventional antiwrinkle finishing is the disruptive effect of the acidic catalyst on fibers at high temperatures. But in sol‐gel method, metallic alkoxides and organic solvents are used in mild conditions that provide tensile strength and color retention [78–80].\n
In antiwrinkle sol‐gel applications, mixed sols with conventional agents can also be applied and different combinations like DMEU/SiO2 (dimethylolethyleneurea/silica), TEOS‐TTB/DMDHEU (tetra ethoxysilane‐titanium (IV) n‐butoxide/dimethylol dihydroxyethylene urea), BTCA‐MAH/SiO2 (1,2,3,4‐butanetetracarboxylic acid‐maleic anhydride/silica), BTCA‐SHP/TEOS‐GPTMS (1,2,3,4‐butan tetracarboxylic acid‐sodium hypophosphite/tetraethoxysilane‐glycidylpropyloxytrimethoxysilane), DMDHEU/TEOS‐GPTMS were evaluated for antiwrinkle finishing and their effects on physical properties of cotton in previous studies [75, 78–81]. These combinations were also found to have advantages in terms of abrasion resistance [75], heat resistance [78], and UV‐light resistance [79] as well as antiwrinkle effect.\n
Schramm and Rinderer treated the cotton fabric with BTCA and/or nanosol containing GPTMS together with metal alkoxides such as aluminum isopropoxide (AIP), titanium tetra isopropoxide, and zircon tetrabutoxide (ZTB) or hydrophobic trialkoxysilanes such as methyltriethoxysilane (MTEOS), octyltriethoxysilane (OTEOS), or Dynasylan F8815 (fluoroalkyl functional oligosiloxane) to impart antiwrinkle properties. Treatment only with metal alkoxides led to no improvement of their anticrease properties, while treatment with GPTMS developed their anticrease properties. Moreover, the addition of AIP and OTEOS or MTEOS to GPTMS solution caused the increase of dry‐crease recovery angle (DCRA) of the fabrics treated with the solution, respectively, from 263° to 289°, 290°, and 294°. Tensile properties of fabric treated with GPTMS solution decreased 10% when compared to that of untreated fabric. The addition of AIP solution to GPTMS solution brought on further 10% loss of their tensile strength, while the addition of OTEOS and MTEOS solutions to solution containing GPTMS and AIP induced to increasing 10% of the tensile strength with regard to tensile strength of fabrics treated with solution containing GPTMS and AIP. The treatment with GPTMS solution containing AIP or AIP together with F8815, MTEOS, and OTEOS solutions ensured the enhancement of contact angle values of the fabrics, respectively, from hydrophilic to 112°, 147°, 145°, and 136° corresponds to excellent hydrophobic properties. They also found that BTCA pretreatment improved the anticrease properties of the fabrics treated with GPTMS solution until 299° of DCRA and led to further loss of tensile strength of the fabric samples treated with GPTMS solution. BTCA pretreatment also did not cause significant change on contact angle values of the fabric samples‐treated GPTMS together with metal alkoxides and/or hydrophobic trialkoxysilanes [22].
It is possible to give various functional properties to textile materials in one step by the combination of compatible inorganic precursors, thanks to sol‐gel technology and the finishing like this is called multifunctional finishing. Multifunctional finishing has drawn much attention in the last decades with many studies on this subject. Table 1 summarized some researches about various functionalities on textile materials treated with in situ sol‐gel method and sols with nanoparticles [82–101].
|Sol preparation
|Precursor or NPs
|NP binding
|Other chemicals/function
|Ref. no.
|NP sols
|Anti‐UV, rubbing fastness
|Ethanol, water
|Polyacrylate/adhesive, NM‐5263/ thickening agent
|Dodecanol/nonsurfactant template
|NP sols
|UPF, hydrophobicity, antibacterial, mechanical strength
|Co/Pes (65/35, 20/80)
|TiO2NP, ZnONP
|Acrylate‐based binder
|NP sols
|Electroconductive, antibacterial
|Co, CV
|PVP/stabilizer, EG/reducing agent, NaCl/mediating agent
|In situ sol‐gel
|Antibacterial, self‐cleaning
|Acrylic acid/plasma polymerization monomer
|NaBH4/reducing agent
|In situ sol‐gel
|UV‐resistance, thermal properties
|Titanium butoxide
|Ethanol, water
|Acetic acid
|MPTMS/graft polymerization monomer
|In situ sol‐gel
|Antibacterial, antifungal, abrasion, pilling resistance
|GPTMS, aluminum isopropoxide
|Ethanol, water
|Ag/CuNP/bioactive additive
|In situ sol‐gel
|UV‐protection, antibacterial, dyeing
|Ethanol, water
|Acetic acid
|CHPTMAC/cationization agent, dyes
|In situ sol‐gel
|Surface bonding, carrier for chemicals / drugs / therapeutic
|PES, Co
|Ethanol, water
|Sodium silicate solution/ nucleation agent
|In situ sol‐gel
|Flame retardancy
|Ethanol, water
|Dimethyl phosphonate
|In situ sol‐gel
|Thermal resistance, water‐repellency
|PVS (with VTES)
|Ethanol, water, toluene
|In situ sol‐gel
|Antibacterial, self‐cleaning
|Zinc nitrate
|Tragacanth gum/reducing, stabilizing, binding agent
|NP sols
|Superhydrophobicity, oil‐water separation, stain repellency, self‐cleaning
|Co, Bamboo, lignocellulosic
|TiO2NP, SiO2NP, VTES
|In situ sol‐gel
|Antibacterial, abrasion resistance
|TEOS, zinc acetate
|Ethanol, water
|In situ sol‐gel
|Photocatalytic activity, UV‐protection
|Acetic acid
|In situ sol‐gel
|Thermal resistance
|In situ sol‐gel
|Photocatalytic activity
|Acetic acid, HCl
|[97, 98]
|In situ sol‐gel
|Sweat pH sensing
|Halochromic dye/litmus
|In situ sol‐gel
|Flame retardancy
|Ethanol, water
|H3BO3, Zn3B2O6, NH4HB4O7/ flame retardants
|In situ sol‐gel
|Hydrophobic, conductive
Memon et al. treated polyester fabrics with titania‐doped silica nanosols. It was observed that the antiwrinkle and UV‐protection properties developed, while air permeability and whiteness index values decreased only slightly [102].\n
Onar and Mete developed water‐oil–repellent and flame‐retardant cotton fabrics by sol‐gel method or knife‐over‐roll coating using a one‐step treatment. The nanosol containing TEOS as a precursor, hexadecyltrimethoxysilane as a precursor with water‐repellent properties, and guanidine phosphate as a flame‐retardant agent were prepared for using at pad‐dry‐cure process. On the other hand, the combination of the nanosols and various polymers such as polyacrylate, polyvinyl acetate (VA), and polyurethane dispersions and fluorocarbon polymer was applied to cotton fabric by knife‐over‐roll process. They found that the fabric coated with nanosols containing VA polymer relatively has good durable water‐oil repellency and flame retardancy properties [103].\n
Chakrabarti and Banerjee prepared multifunctional cotton fabric that shows enhanced mechanical strength, water and stain repellence, antimicrobial properties, UV‐blocking capacity, and self‐cleaning characteristics by zinc oxide nanoparticles [104].\n
Ibahim et al. enhanced both the functionality and pigment‐printability of linen/cotton‐blended fabric in a one‐step process by the incorporation of inorganic nanomaterials such as silver (Ag‐NPs), zinc oxide (ZnO‐NPs), zirconium oxide (ZrO2‐NPs), or titanium dioxide (TiO2‐NPs) [105].\n
Mahltig et al. obtained photobactericidal and photochromic textile materials with UV‐protective properties by sol‐gel technology and stated that especially epoxysilane‐modified sols led to promising results [106].\n
Pan et al. prepared superhydrophobic (water contact angle of 146.27°) and UV‐blocking (UPF value of 164.06) cotton fabric by nano‐alumina sol via sol‐gel method [107].\n
Simoncic et al. compared the sol‐gel application procedures as one step or two steps in terms of multifunctional water‐oil–repellent and antimicrobial properties of cotton and found that one‐step procedure was more effective in the production of coatings with water‐ and oil‐repellent properties, while two‐step procedure provided higher antibacterial activity, as well as better washing fastness [108].\n
Mahltig and Fischer applied sol‐gel coatings to viscose and polyamide textiles in order to give functional properties like water repellency and antimicrobial activity at the same time and found that textile comfort properties were also preserved [109].\n
Textor and Mahltig described a sol‐gel–based surface treatment for the preparation of water‐repellent antistatic textiles and applied it to two types of textiles (100% polyester fabric and 65% polyester and 35% cotton‐blended fabric). They obtained sufficient water repellency and antistatic properties simultaneously and suggested that this concept can be adapted to the alternative multifunctional surface coatings other than combining water repellence with antistatic properties for textile materials [110].\n
El‐Shafei et al. purposed to develop flame‐retardant and antibacterial cotton fabric by treatment with BTCA solution containing sodium hypophosphite (SHP) as a catalyst and chitosan phosphate synthesized and then TiO2 nanosols. Increase of TiO2, SHP and chitosan‐phosphate concentration led to increase of LOI values of the fabric treated with them. The combination of BTCA and chitosan phosphate causes lower crease recovery angle than that of treatment with only BTCA. The antibacterial activity of the fabrics against S. aureus, E. coli, Candida albicans (fungus), and Aspergillus flavus (fungus) developed with the increase of TiO2 and chitosan‐phosphate concentration [111].\n
Rana et al. investigated the water repellency, UV protection, and antibacterial properties of cotton fabric treated with silica nanosols containing dimethyl dimethoxysilane (DMDMS) and TEOS as precursors and AgBr‐TiO2 nanoparticles, which were synthesized by using silver nitrate, potassium bromide, and titanium tetrachloride as precursors, by spray coating process. The treatment with silica nanosols with and without AgBr‐TiO2 particles gave rise to, respectively, 145.8°, 149.1° and 136°, 144.3° of contact angle values of the fabrics before and after washing process. Nevertheless, the fabrics treated with silica nanosols along with AgBr‐TiO2 particles have excellent UV protection with 41.9 of UPF value and good antibacterial activity with 99.88% bacterial reduction against E. coli [112].\n
Vasiljević et al. prepared six different solutions containing 1H,1H,2H,2H‐perfluorooctyltriethoxysilane (SiF), 3‐(trimethoxysilyl)‐propyldimethyloctadecyl ammonium chloride (SiQ), and P,P‐diphenyl‐ N‐(3‐(trimethoxysilyl)propyl) phosphinic amide (SiP) together with TEOS or organocyclotetrasiloxane 2,4,6,8‐tetrakis (2‐(diethoxy(methyl)silyl)ethyl)‐2,4,6,8‐tetramethyl‐cyclotetrasiloxane. Optimization of water, oil repellency, flame‐retardant, and antibacterial properties of the fabric treated were carried out. They revealed that the fabrics treated at optimized conditions have superhydrophobic properties with 161° of contact angle and 4° of sliding angle and good antibacterial properties with 100 and 81.6% bacterial reduction against, respectively, S. aureus and E. coli but not good oil repellency properties (3) [113].\n
Gu et al. proved the flame retardancy and water repellency properties of cotton fabric treated with phosphorus‐doped silica hydrosol containing hexadecyltrimethoxysilane. They found that the LOI value, residue amount at 600°C, and contact angle of the fabrics increased from, respectively, 18.5, 13.3% and hydrophilic to 29.4, 29.7, and 134.6° when compared to that of untreated fabric. Their onset temperature and pHRR values decreased from, respectively, 320 and 235°C to 217 and 81.46°C [114].\n
El‐Naggar et al. stated that the cotton fabrics treated with titania nanosols in situ synthesized and then urea nitrate solution by two‐step process possessed excellent antibacterial properties with, respectively, 99.4 and 99.37% bacterial reduction against to S. aureus and E. coli and excellent UV‐protection properties with 42.11% UPF value with good durability to washing [115].\n
Sivakumar et al. studied the antibacterial, UV‐protection, soil release, and self‐cleaning properties of the cotton/polyester fabric subjected to TiO2 nanoparticles, which were synthesized using titanium isopropoxide as precursor and then modified with 3‐aminopropyltriethoxysilane and silicon oil, by pad‐dry‐cure process. The maximum photocatalytic and antibacterial activities were obtained for the fabrics treated with modified TiO2, while the maximum UPF values were obtained for the fabric treated with unmodified TiO2 [116].\n
Behzadnia et al. developed the photosonochemical synthesis of N‐Ag/TiO2 on wool fabric using titanium isopropoxide and silver nitrate as precursors and ammonia as nitrogen doping. The effect of pH, sonication, and precursor concentration on antibacterial and photocatalytic properties of wool fabrics treated were researched. Ag doping to N‐TiO2 nanocomposites on wool improved self‐cleaning, photocatalytic, and antibacterial properties of N‐doping TiO2 nanocomposites on wool, while sono‐treated samples containing N‐Ag/TiO2 possess higher self‐cleaning and photocatalytic properties when compared to stirred fabrics containing N‐Ag/TiO2 [117].
Since 1960s, sol‐gel‐coating method on the substrates like metal, glass, and ceramic has been studied extensively. In the last decades, researches about sol‐gel technology have focused on enabling functional properties to textile materials as an alternative to conventional textile finishing treatments. In textile finishing, flame retardancy, water or oil repellency, UV protection, antimicrobial activity, and antiwrinkle effect were already studied by sol‐gel method. In addition, multifunctionality means that two or more of these properties are evaluated in combination and investigated in terms of washing durability, textile comfort, and physical properties. It is an important fact to ensure multifunctional properties in one step, and by nanotechnological sol‐gel method, this problem can be achieved and moreover, eco‐friendly treatments can be applied in textile finishing due to less harmful chemical use. Therefore, sol‐gel technology is expected to be used in plenty of textile finishing processes and promising studies are the starting points for further developments in future.
The role of the ionosphere in providing human life is difficult to overestimate. This role was great in the pre-satellite era and multiplied after the launch of an artificial Earth satellite. This role is most fully represented in [1], in which various technological systems are divided into two categories: (1) systems which cannot exist without the ionosphere (VLF-LF communication and navigation, MF communication, HF communication, "short-wave" listening, OTH radar surveillance, HFDF and HF SIGINT), and systems on which the ionosphere makes the big impact (a satellite communication, satellite navigation (i.e., GPS & GLONASS, etc.), space-based radar and imaging, terrestrial radar surveillance and tracking, and others). This shows how it is important to study the ionosphere. Classical methods of studying the ionosphere from the Earth's surface are the pulsed sounding—the sending of radio pulses and the observation of their reflections from various ionospheric layers with the measurement of the delay time and the study of the intensity and shape of the reflected signals. Measuring the reflection height of radio pulses at different frequencies, determining the critical frequencies of different regions, that is, frequencies for which the given area of the ionosphere becomes transparent, it is possible to determine the value of the electron density in the layers and the virtual altitudes for the given frequencies, hence to select the optimum frequencies for the specified radio paths. This is the principle of work of the main device namely of ionosonde. Its use for many years in many parts of the globe has made it possible to obtain a huge array of data and develop predictive models of various parameters. The breakthrough occurred with the advent of satellites, in particular, with the installation of ionosondes on satellites [2]. Here, there is a wide variety of methods. Let us list some of them with a brief description. The first is external (topside) sounding (TS, f < foF2, where foF2 is the critical frequency of the basic layer of the ionosphere F2). An example is the on-board ionosonde "IS-338," in future projects, the on-board ionosonde "LAERT" [3]. The second is direct transionospheric sounding (TIS) (f > foF2). In this case, the signal is emitted from the spacecraft, and the reception is on the Earth. The third option is reverse transionospheric sounding (RTS) (f > foF2). In this case, the signals emitted by the transmitter from the Earth are received by the receiver on the satellite. All of these methods were implemented in a variety of experiments on spacecraft series Alouette, Arial, ISIS, Intercosmos-19 and Kosmos-1809, IC Bulgaria 1300, and others. An example of ionograms of TS (the left curve) and RTS (the right curve) of "Kosmos-1809" is shown in Figure 1.\n\n
A detailed analysis of the current state of the TS method is given in [4]. The RTS method is presented in [5]. In all cases, a number of important tasks were solved. One of them is the mathematical support of methods [6]. The second problem is the synchronization of airborne and ground ionosondes [7]. Figure 2 shows a system for synchronous ionospheric sounding using all methods of radio pulse sounding. The features of synchronous operation of the terrestrial-satellite system are presented in the examples of synchronization schemes for previously launched Russian ionosondes.\n\n
As to scientific results, it is difficult to select something from hundreds of, if not from thousands of, the publications based on processing of millions of ionograms. As examples, it is possible to note the first publications [8] and the detailed review of results from Alouette1, Explorer 20, Alouette2, Explorer 31 [9]. Data of topside sounding have played a big role in improvement of various models of the ionosphere with the use of data of Intercosmos-19 and Cosmos 1809 [10], Alouette1-2, ISIS-1-2 [11] and later satellites [12]. In the paper [13], application of ionospheric topside-sounding results to magnetospheric physics and astrophysics is presented. From the latest publications, it is possible to specify the study of behavior of high-latitude N(h)-profiles during strong magnetic storms with use of huge database of digital topside ionograms [14]. It is underlined in [4] that the interest in the modification and the use of TIS has increased recently in connection with the need to monitor the polar region. On the one hand, this is due to the fact that high-latitude regions were always problematic zones because of the small number of ionosondes and the enormous spatial and temporal variability of the ionosphere due to the magnetospheric influence. On the other hand, interest increased due to increased scientific and economic activities in these regions.\n
In this chapter, the main emphasis is also on the study of the polar region, that is why we consider the existing proposals. In [15], the authors, noting such shortcomings of the TIS method, using low-altitude satellites, associated with the high speed of the satellite and its projection to the Earth's surface, as impossibility of exact separation of the spatiotemporal characteristics of the variability in a diagnosed region and large time delay between the measurements of the ionospheric parameters and the processing and analysis of the measurement data, have proposed the use of satellites in the geostationary orbit. Since it is proposed to install a transmitter on a satellite, the main attention in [15] is given to the energy problem. A calculation of ray trajectories is carried out in a two-dimensional plane of propagation from a satellite to a receiver point formed by combined vertical profiles of the electron density. Up to a height of 2000 km, Ne(h) is taken from the IRI model and then is "sewed" to the NeQuick model [16] in such a way that the electron density becomes zero at a height of 36,000 km. Calculations were made for the transmitting antennas as weakly directed vertical or horizontal dipoles. Of the three types of signals: simple smooth pulses, linearly frequency modulated (LFM) and phase and code manipulated (PCM) used for sounding the ionosphere, estimates are made for the first and second types for signal-to-noise ratio (S/N) of 20 dB. For the first type, the field strength at the receiver was ~6 μB/m for radiated power of 1 kW. The use of LFM signals of ~100 μs duration is intended to reduce the radiated power due to the complexity and broadband of the signals. At S/N = 20 dB, the radiated power can be 100 W. An example of the model transionogram and the received field strength is shown in Figure 3.\n\n
The paper [17] is a definite addition to [15], of which deserves an attention remark about another disadvantage of this method TIS and RTS, namely, that these techniques only determine two parameters: the critical frequency (foF2) and the height of the maximum of the F2 layer (hmF2) in the sub-satellite point, without defining N(h)-profile, and that to date conducted only one successful experiment about reconstruction of a bottom Ne(h)-profile of the F2 layer using them [18]. It is possible that namely for this reason, the methods of TIS and RTS have not been developed in the world. Explanation was made for differences of the proposed methods of TS, TIS and RTS: (a) a source of information is not a traditional ionogram and ionogram, retaining only radio sounding signals; (b) ionosonde becomes a measuring tool, and the system of a single-board broadband transmitter module (BTM) and a network of ground receiving k modules (GRM) with the tuning frequency tunable synchronously with the on-board BTM. Therefore, the method is called as multifrequency ionospheric radioscopy method. The difference between [17] and [15] is information on experimental data confirming the possibility of implementing the proposed method, but these data are indirect. The approach described in [19] is based on real experiments in the Arctic using external sounding [20]. These experiments revealed a shortcoming of use of circular low orbit, namely the inability to determine the dynamics of the ionospheric irregularities; therefore, the use of space satellites with highly elliptical orbits with an apogee over the North Pole was proposed. However, it was immediately noted the complexity of using such orbits, consisting in the difficulty of choosing the time of ionosonde location over the investigated area. To overcome this difficulty, it is proposed to use solar-synchronous orbits. It is shown that there is a number of such orbits for monitoring Arctic of Russia: the first orbit has an apogee of 40,000 km (the North Pole) and a perigee of 500 km (above the South Pole) during one revolution of 12 h, a second orbit has an apogee of 20,343 km, perigee 485 km, the time of one revolution is 6 h, the third orbit has apogee 11,829 km, perigee 500 km. The choice of the orbit is mainly influenced by the significant energy loss of the probing signal for propagation in free space. For example, the difference in signal power loss from reflection from the Earth between a high-orbit and low-orbit ionosondes can be about 100 dB, and the transmitter power is limited. As a solution, signals with phase-code modulation are selected. Calculation of the sounding parameters has shown that a power of 600 W will not suppress the remaining experiments on the satellite, and at the same time, this power will be enough to assure confident reception of signals reflected from the ionosphere of the Earth on a high-altitude apogee satellite. All these proposals indicate the relevance and prospects of such methods.\n
The main element of the methods [15, 17, 19] is the installation of an ionosonde on the spacecraft, but as noted in [21], an ionosonde for TS [19] or a powerful on-board transmitter for TIS [22] not yet created. Even more important is the problem of electromagnetic compatibility on board of a satellite. The proposed principle is a kind of RTS and consists of the use of an on-board receiver and a terrestrial transmitter, which makes it possible to increase the energy potential of the sounding channel due to a more powerful ground-based transmitter. The author of [21] showed the possibility of RTS from highly elliptical orbits up to 40,000 km. The details are as follows. It is proposed to use a terrestrial ionosonde of the "Parus" type with a typical rhombic antenna, only an ionosonde receiver with shortened antennas should be installed on board (the upper part of the frequency range is used). For comparison, the calculation is performed for the orbits proposed in [19], and the characteristics of which are given in Table 1. The orbital number, apogee and perigee, eccentricity and period of revolution are given.\n
|Orbital number\n
|Apogee (km) above the North Pole\n
|Perigee (km)\n
|Circulation period (h)\n
The possibility of successful sounding of the ionosphere by means of satellites is largely determined by the energy potential of the Pv channel of the satellite-Earth. The parameter Pv is estimated in [19] for TS and in [17] for TIS. To assess Pv, in the case of RTS, ground and airborne antennas are used, the directional patterns and gain factors are shown in Figures 4 and 5. The tables, included in the form of frames, give an idea of the quantitative evaluations: Freq—frequency, R—active resistance, jX—reactive resistance, Ga—gain, F/B—ratio of direct radiation and reverse power, and ON—auxiliary symbol.\n\n\n
The characteristics of the assumed on-board receiver and ground transmitter are given in Table 2.\n
|Receiver of the ionosonde "Laert"\n
|Transmitter ionosonde "Parus-A"\n
|Range of sounding frequencies (MHz)\n
|Installed programmatically\n
|Pulse power of the transmitter (kW)\n
|Up to 20\n
|Lamp version\n
|Pulse width (μs)\n
|Pulse repetition frequency (Hz)\n
|Installed programmatically\n
|Bandwidth (kHz)\n
|(−3 dB)\n
|Sensitivity (μV)\n
|Not less than 5\n
|With S/N 10 dB\n
|Dynamic range (dB)\n
|Not less than 100\n
|Up to 120\n
|Number of discrete frequencies\n
|Not less than 400\n
|Changes programmatically\n
|The law of adjustment in the range\n
|Changes programmatically\n
|Instability of reference frequency\n
|Not worse than 10−8\n
|Not worse than 10−8\n
The energy potential of Pv with RTS for orbits with a height of 10–40,000 km was calculated according to the known relation from [23]. The results are shown in Figure 6. The red line presents the calculation results for the frequency of 5 MHz, green—10 MHz, blue—15 MHz, dark blue—20 MHz.\n\n
In the paper [22], the calculation of the power of the communication channel was carried out for TIS in the circumpolar region, and it is shown that "the main source of background noise is the radiation of powerful radio stations on the Earth's surface." That is why, for comparison, Figure 5, the dashed curve shows the level of interference from a 21-m broadcast transmitter with a power of 50 kW at the altitudes of the satellite. The peculiarity of the on-board ionosonde "Laert" is a two-channel polarization reception, which allows reducing to a minimum the losses from the polarization mismatch. Losses in antenna feeders and filters are assumed to be 3–6 dB. The obtained values of Pv show the excess of the signal above the interference to 6–10 dB even for distances exceeding 40,000 km. The worst reception conditions are near the cutoff frequency. In the case under consideration, this frequency of 5 MHz corresponds to foF2, and it is possible to use a corresponding estimation of absorption. However, in this case too, at a low signal-to-noise ratio (S/N), the transionograms can be recorded, as was shown in the experiments "Intercosmos-19" and RTS—with "Cosmos-1809." The RTS sounding mode, in which one pulse is emitted at each frequency, ensures maximum diagnostic efficiency, but the "Parus-A" and "Laert" ionosondes are potentially designed to work with complex signals, which can be used to increase the S/N ratio during a significant increase of the absorption in the polar ionosphere during different disturbances. Thus, the RTS mode is energetically favorable for the sounding channel, and it does not require, as with the TIS in [22], to install on the satellite a powerful transmitter that affects the operation of other on-board systems to ensure the requirements of the electromagnetic compatibility. Obviously, working with complex signals, with the accumulation of signals at each sampling frequency [19], significantly reduces the resolution concerning space. The synchronization problem can be solved with the "binding" of the chronographs of the ground and airborne ionosondes to the exact time of GLONASS or GPS [17, 21], taking into account the ephemerides of the satellite.\n
These results allow us to propose a somewhat different scheme of the RTS method, namely, the use of the GLONASS platform to install the receiver (an application of this method is given in Section 4).\n
Among large number of empirical models of the ionosphere, the International Reference Ionosphere (IRI) is the most widely used, tested by huge scientific community and constantly modified. The development of this model was started in the late 1960s and was carried out under the umbrella of Committee on Space Research COSPAR and International Union of Radio Science URSI. Currently, it is an international standard for the determination of ionospheric parameters [24]. This is a statistical average model based on a huge amount of data from both terrestrial and satellite measurements. For the propagation problems, its most important parameters are: the critical frequency foF2 of the F2 layer (or the maximum density NmF2 bound by the linear ratio with the square of the critical frequency), the height hmF2 of the maximum of the F2 layer, the propagation coefficient M3000F2 determining the maximum applicable MUF frequency for the 3000 km path, the altitude profile of the electron density N(h), the total electron content TEC of the ionosphere. The parameters are determined using the coefficients of CCIR and URSI, obtained by the Fourier expansion according to the data of the 1960s and the 1980s. The driving parameters are the solar activity indices. The input parameters are the date, latitude and longitude of the point on the globe. The shape of the N(h)-profile of the lower part of the ionosphere is determined by parameters B0 and B1, for which there are two options: tabular and Gulyaeva data, but they do not have advantages over each other, although the tabular variant is most often used. There are several basic versions of the model, reflecting the most significant stages of its modification: IRI79, IRI90, IRI95, IRI2001, and IRI2007. The latest modifications of the IRI2016 model are presented in [25]. They include two new options for hmF2. The review of the last steps for the transition from climatological character of the model to the description of ionospheric conditions in real time by adaptation to the current diagnostic data is presented. At present, there is a new version of IRI-Plas [26]. The main distinguishing features of this model are: (1) introduction of a new height scale for the upper ionosphere, (2) taking into account the plasma sphere part of the profile and (3) adapting the profile to the experimental value of TEC. The advantages provided by these features are indicated in [27].\n
Like a situation with ionospheric modeling, there is a number of methods of radiowave propagation calculation in the model ionosphere. In this chapter, the most theoretically developed method of trajectory calculations is used. Briefly, it consists of the following. In general, the calculation of trajectories follows the classical ray tracing procedure [28]. A numerical solution of the local dispersion equation is found by transforming it to a system of differential characteristic equations with respect to spatial and ray coordinates in the model ionosphere as the sum of the basic unperturbed part and the additional perturbation: \n\n where N0 is the unperturbed "base" part described by the international model IRI-2016, with allowance for the possibility of correction in the presence of experimental vertical sounding data, \n\n and \n\n are the perturbations created by traveling ionospheric disturbances (TID).\n
Using the proposed method, RTS allows to study in detail not only the large-scale structure in the form of layers, but also to determine the parameters of quasi-wave disturbances, including traveling ionospheric disturbances (TIDs) in the outer ionosphere. The technique was proposed and tested according to the data of RTS on the Intercosmos-1809 satellite. Details of the method are presented in [29]. It is the singular spectrum analysis (SSA) method [30], which is modified to select a one-dimensional latitudinal series of observations of the quasi-harmonic TID component at a fixed height. The investigated series are the values of the electron density at a fixed height in the function of the geomagnetic co-latitude. These series are decomposed into a sum of series, each of which corresponds to a trend, a periodic component and, possibly, noise. The basic algorithm of the SSA method includes four steps: embedding, singular decomposition, grouping, and diagonal averaging. Modification of the basic SSA method consists of removing the trend and analyzing the remaining term characterizing the disturbance. The main contribution is given by decomposition [31]. The method was applied to the case of ionospheric sounding from the Kosmos-1809 satellite on 06.03.1987, pass 1079, UT = 8.82–8.92 h along geomagnetic longitude ~128° E. The geomagnetic situation during the experiment was characterized by the planetary index Kp = 2+. The spatial distribution of the normalized values of the electron density in the altitude range of 300–400 km is shown in Figure 7.\n\n
Figures 8 and 9 show the results of the determination of the electron density perturbation at an altitude of 350 km.\n\n\n
Figure 8 shows that the disturbance is a fragment of a wave train, not a harmonic. This clearly manifests itself when considering the spatial picture of the disturbance depicted in Figure 9. In this particular case, we are dealing with a weak perturbation with a wavelength of L ≈ 500 km, damped in the vertical and horizontal directions.\n
TEC measurements by means of signals from satellites began literally with the launch of the first satellite [32]. Since the mid-1960s, continuous measurements of the rotation of the Faraday polarization plane at one point with the help of geostationary satellites have been carried out. Since the mid-1970s, measurements have been carried out using differential group delays and Doppler shifts. As noted by many researchers, the TEC parameter, like the critical frequency foF2, has become the main parameter for describing the behavior of the ionosphere. A huge number of GPS receivers around the globe, the availability of data on the Internet has allowed and allow scientists to study the local, regional, global characteristics of the ionosphere independently, quickly and simultaneously. The results are presented both on the basis of the data of local networks of GPS receivers, and data of global maps. In this chapter, the TEC values are calculated from the IONEX file data (site
Since any empirical model is problematic for the high latitude region, it is necessary to obtain quantitative estimates of the accuracy of the model in the investigated region. In our case, it is the European part of Russia. Figure 10 gives an example of a comparison of the model and experimental ionospheric parameters for the highest latitude Longyearbuen station (78.2° N, 15.9° E). Its results are compared with the results of the mid-latitude station Juliusruh, which is a reference station. Results are given for mean solar activity from those vertical sounding data that were available for the Longyearbuen station (2011–2014). Absolute |ΔfoF2| (in MHz) and relative deviations σ (in %) are compared for three options: (1) model values and experimental medians ("med" icon), (2) model values and monthly average experimental instantaneous values ("ins"), and (3) values calculated using experimental TEC and equivalent slab thickness of the ionosphere τ ("τ" icon). The latter should be compared with option 2.\n\n
The values averaged over the year during the data availability period of Longyearbuen station are given in Table 3. Each result column contains |ΔfoF2| and σ. Figure 9 and Table 3 show that the average deviations for options 1 and 2 for both stations are not much different. This indicates that the IRI model can provide foF2 with accuracy close to mid-latitude values. Using TEC improves the correspondence between calculated and experimental values in 1.5–2 times; however, here, the results for Longyearbuen station are worse than for Juliusruh. The reason lies in the small number of stations contributing to the construction of global TEC maps, and at large angles of slant TECs associated with the boundary latitude of navigation satellites.\n
|0.42, 11.90\n
|0.64, 17.73\n
|0.38, 11.73\n
|0.44, 10.35\n
|0.65, 14.96\n
|0.28, 6.94\n
|0.36, 9.82\n
|0.62, 17.18\n
|0.43, 12.70\n
|0.76, 17.95\n
|0.99, 23.87\n
|0.38, 9.13\n
|0.48, 11.40\n
|0.69, 16.54\n
|0.40, 10.71\n
|0.32, 6.83\n
|0.65, 13.98\n
|0.31, 7.29\n
|0.70, 13.72\n
|0.85, 17.34\n
|0.42, 9.64\n
|0.62, 11.47\n
|0.83, 15.65\n
|0.30, 6.22\n
An interesting result was obtained by the author of the model SDMF2 (Satellite and Digisonde Data Model of the F2 layer) for quiet geomagnetic conditions [33] when compared with the IRI model [34]. A comparison was made using data from eight ionosondes in various regions of the globe to evaluate the effects of different solar-ionospheric indices [34]. Of all the stations, the best fit of the model and experimental values of foF2 were obtained for the Salekhard station (66.5 °N, 66.5 °E).\n
The most important is the use of the model to specify propagation conditions on oblique paths. In [35], the calculated and experimental ionograms of oblique sounding were compared on 17 high-latitude HF paths of AARI during the period of quiet conditions on February 13–14, 2014 using the IRI-2012 model. It is shown that the IRI model without correction based on current diagnostic data, even under quiet conditions, underestimates the experimental values. Correction according to the current diagnostic data allows us to substantially approach the calculated values to the experimental ones. As the current diagnostics data, the critical frequencies measured by ionosondes located near the paths or calculated using the experimental values of TEC were used. It was obtained that the relative error of the initial IRI model in obtaining the values of the maximum useable frequency MUF averaged over all cases and the provided 23.6% for one hop was reduced by 4% when using the TEC and by 6% when using foF2. Analysis of experimental data showed that on high-latitude paths, there are a number of unpredictable features that occur even in quiet conditions. These include TID, M and N-modes, lateral modes, triplets and diffusivity. Below, the results of additional comparisons, including for disturbed days on September 6–8, 2017 are presented for ionograms of two oblique paths Cyprus-Lovozero (path length 3600 km) and Gorkovskaya-Lovozero (path length 900 km). It should be noted that the IRI model, like any statistical model, provides median (mean) values, so the model values should be compared with the experimental medians of the parameters. However, very often, model values are used as daily values, that is, instant, for the lack of others. In this case, the error can be large, especially during disturbances. In this case, such disturbance was observed from September 6 to 8, 2017. This fact is illustrated in Figures 11 and 12.\n\n\n
For this case, Table 4 gives mean monthly (Δ), absolute (|Δ|) deviations and estimates of absolute and relative errors.\n
|RMS (%)\n
|0.064 MHz\n
|0.22 MHz\n
|0.25 MHz\n
|18.9 km\n
|19.5 km\n
|26.7 km\n
Relative errors lie in the range of 6–10%. Of course, this is a very small statistic, but it coincides with the results of [36] and allows us to confirm on the new data an important conclusion about the possibility of using the IRI model in high latitudes. Figure 12 shows the difference in the disturbed values of foF2 from the medians. We see a significant positive disturbance in foF2 on September 7 and a negative perturbation in the behavior of both parameters on September 8. As it was noted earlier, a feature of the IRI model is its ability to be adapted to the current diagnostic data. This plays a big role in the calculation of oblique ionograms, which is illustrated in Figure 13. This figure shows the experimental MOF values for one and two hops, as well as the experimental value of foF2 in the center of the path. The black dots show the Dst index reduced in five times in absolute value. The right graph shows the values calculated by the numerical method. Red triangles refer to the experiment, black dots describe the curve for the original IRI model, and blue circles represent the results for model adaptation.\n\n
This allows us to conclude that the comparison of the parameters of HF propagation testifies that the model can be used in the high latitude region as yet, especially at adaptation to the data of the current diagnostics.\n
Since the main area of application of the proposed principle is the polar region, it is necessary to point to an important result of [37]. It is shown that when recalculating a slant TEC into a vertical one, the traditional assumption of the ionosphere in the form of a thin layer is admissible. The height of this layer is associated with the position of the sub-ionospheric point. The calculated positions of this point are shown in Figure 14. The vertical axis represents the maximum latitude of the sub-ionospheric points in degrees, along the horizontal axis the latitude of the receiver in degrees is postponed.\n\n
This indicates that in high latitudes, there is no restriction on the visibility of the satellite, that is, on sounding the high-latitude ionosphere according to GNSS signals, and allows solving such tasks as tracking the position of high-latitude structures: mid latitude ionospheric trough (MIT) and auroral oval. The situation with the study of these structures is as follows. The trough generally consists of three parts: an equator wall, a trough minimum and a pole wall. Because of the large electron density, gradient on either side of the trough affects radio wave propagation, the exact position of the trough is very important for solving some problems, such as trans-ionospheric communication and navigation [38]. The main regularities of the behavior are obtained, and the MIT model is developed using foF2 [12] for night winter conditions—the period of the most probable occurrence of a trough. The corresponding behavior of the TEC shows that TEC can be used to identify the position of the dip [39]. It is shown that TEC always shows the presence of the trough.\n
The auroral oval in the high-latitude ionosphere is the boundary of the polar cap and is defined as the region of the ionosphere, which is the projection of the plasma layer and cusp along the lines of force of the geomagnetic field. The position of the auroral oval zone is projected onto the boundary of the outer radiation belt of the Earth. During magnetic storms, it shifts toward the mid-latitude, following a shift in the outer radiation belt. The displacement is almost linear and can reach 10 degrees with the growth of the Kp index to 5. With greater growth of Kp, the auroral oval boundary can jump discontinuously in the middle latitudes due to a significant distortion in the structure of the magnetosphere. In the auroral oval zone, the frequency of failures and refusals of radio communication and navigation equipment increases [37], so it is important to monitor its position. The possibility of such tracking not only in the meridional but also in the longitude directions is shown in [40].\n
An additional advantage of using the GLONASS platform for implementing the RTS method is associated with the ability to determine the N(h) profile from the initial height of the ionosphere to the height of the platform. This is due to the possibility of determining the critical frequency that can be used to adapt the model. The simulation results are shown in Figure 15 for conditions of February 21, 2014, UT = 12, the satellite's altitude is 20,000 km, the satellite's latitude is 68.96°, longitude is 33.0°, the transmitter's latitude is 68.56°, longitude is 33.08°. The left panel of Figure 15 shows the N(h)-profile as Fn(h)-curve (N is proportional to Fn2), the middle—trajectories of waves, and the right panel shows the transionogram.\n\n
It can be seen that foF2 can be determined with an accuracy of 0.25 MHz. In experiments, it is possible to use the basic advantage of the model IRI-Plas, namely, its adaptation to measured value of ТЕС, which allows modifying plasmaspheric part of N(h)-profiles.\n
One more important possible application of the RTS method can be an installation of the receiver on low-flying mini satellites. The launch of such satellites is carried out constantly. It is possible to point out the results presented at the conference [41]. The micro-satellite "Chibis-M" was launched into a near-Earth orbit with parameters close to those of the ISS (513 km altitude, inclination 51°) on January 25, 2012 as a passing load on the cargo spacecraft Progress. It successfully operated for more than 2.5 years. The Vernov satellite was launched on July 8, 2014 to a solar-synchronous orbit with a small eccentricity—the height of the pericenter is 640 km, the altitude of the apocentre is 830 km, the inclination is 98.4°, and the period of revolution is 100 min. The Lomonosov satellite was launched on April 28, 2016 also to the solar synchronous orbit, circular with a height of 490 km, an inclination of 98.4° and a period of 90 min. The realization of these microsatellites has shown that with their help, it is possible to successfully carry out electromagnetic monitoring of the surrounding space environment. A new space project of the Moscow State University is being discussed (Lomonosov "Universal-SOKRAT") to create a grouping of satellites for real-time monitoring in near-Earth space. Methodological aspects of the spatiotemporal resolution of the plasma-wave parameters of the ionosphere with the help of two copies of Trabant MC (2020–2024), simultaneously deduced into an orbit with a height of ~500 km are considered. They intended for investigation of: (a) the mechanisms of occurrence and dynamics of ionospheric inhomogeneities of different scale depending on the active processes on the Sun and on Earth; (b) regularities of changes in plasma-wave and electromagnetic parameters in the ionosphere of natural and technogenic character in a wide dynamic and frequency ranges; (c) applied aspects, consisting in conducting diagnostics of ionospheric manifestations of space weather.\n
The long-term use of satellite sounding data has made it possible to obtain the most important knowledge about near-Earth space. Climatological models of ionospheric parameters have been developed, which have found the widest application in various technological systems. However, at the present stage, it is necessary to provide operational support for these systems with ionospheric information. Here, it is necessary to look for ways of modifying different methods. In the ionospheric models, it is an adaptation to the parameters of the current diagnosis and the use of the total electron content for this diagnosis. A modification is also required in transionospheric sounding methods. It is shown that the main role can be played by the method of reverse transionospheric sounding, combined with the measurement of TEC. The installation of an on-board ionosonde receiver on the GLONASS platform helps to solve much problems. First, there is no need to develop a new platform for the polar high-apogee experiment, and second, the installation of the ionosonde receiver does not violate the electromagnetic compatibility requirements, the "timing" of the ionosonde to the exact time and the ephemerides of the satellite is simplified, and the transionogramms of the RTS can be transmitted through the service channels, besides, sizes of the reception aerial decrease at restriction of a frequency range [21].\n
This work was supported by grant under the state task N3.9696.2017/8.9 from Ministry of Education and Science of Russia.\n
There is no conflict of interest.
IntechOpen offers several publishing options to researchers and research groups looking for a professional partner with a wide, international reach. Our publishing options cover the breadth of scientific publications and ensure an appropriate outlet for your research.",metaTitle:"Why publish with IntechOpen?",metaDescription:"IntechOpen offers publishing options to researchers and research groups looking for a professional partner with a wide, international reach. Our publishing options cover the breadth of scientific publications and ensure an appropriate outlet for your research.",metaKeywords:null,canonicalURL:"/page/why-publish-with-intechopen",contentRaw:'[{"type":"htmlEditorComponent","content":"


text:
Latest topics
Log in
Be An Athletic Supporter!
Donate and get this nifty tag!
StatisticsWe have 12919 registered users
The newest registered user is firstname.lastname@example.com
Our users have posted a total of 185484 messages in 24835 subjects
2017/2018 Schedules
Boys Classic League Field Maps and Status
Girls PPL Schedules and Results
PPL Field Status and Field Maps
Boys PPL Schedules and ResultsIf you want your league schedule here PM me the link!
Player Search
Page 1 of 1 • Share •
Player Search
Invictus United is in need of 2 field players and a keeper. No club dues or training fees. Practice is in Murphy on Tuesdays and Thursdays.
- TxSoccer Lurker
- Posts : 2
Points : 164
Join date : 2018-09-16
Re: Player Search
- TxSoccer Lurker
- Posts : 2
Points : 164
Join date : 2018-09-16
Permissions in this forum:You cannot reply to topics in this forum

subset: commoncrawl


text:
You don't have to travel overseas; try a Western USA Family Holiday. Hit the beach in San Diego to surf and swim. Then head to the Grand Canyon to watch the sun paint the canyon walls and hear rangers explain park geology. Drive on toward dazzling Las Vegas, and, if you dare, venture into Death Valley, the hottest, driest spot in the country, where you'll find volcanic craters, mountain peaks and salt flats. Don't miss the giant sequoias and granite cliffs at Yosemite National Park. End your trip by returning to San Francisco via Monterey, where you can visit the Monterey Bay Aquarium, go kayaking, or journey by boat to spot sea lions, otters and whales.
What to do: Bring your passport, so you can view them from the Canadian and American sides; to visit both, just cross Rainbow Bridge. Board the Maid of the Mist boat from either shore to get right up to the raging water (they give you ponchos so you don't get drenched). By day you'll see rainbows; at night, the falls are dramatically lit, and there are fireworks too! If your kids aren't afraid of heights, they'll also love the bird's eye view from Skylon Tower.
What to do: Miami Beach has the most tropical beaches in the continental United States. Its warm waters are calmer than North Atlantic counterparts and less salty than the Pacific. As you drive to Miami Beach from Miami, you hit your first two must-see attractions. Indoors, there's the internationally recognized Children's Museum that shares an island with Jungle Island — an interactive zoological theme park. Beloved by celebrities just as much as kids, The Sugar Factory on Ocean Drive is also a mustl. It's the most Instagram-worthy restaurant in the world!
WOW AIR: WOW Air as grown at a staggering rate since it first began flying from the USA in 2015. It now flies from 13 U.S. airports, including just-launched service from airports in Cleveland, Cincinnati, Detroit and St. Louis. All of WOW's U.S. flights are to its hub near Reykjavik, where connections are available to more than 20 European destinations. Flights from Iceland to India will provide a new option starting in December 2018. Jeremy Dwyer-Lindgren, special to USA TODAY
Why you'll love it: Ruminate on the Revolution on Beantown's historic streets while following the (free) Freedom Trail, a 2.5-mile, red-lined route that winds past 16 historically significant sites dating back to the American Revolution. Don't miss taking a spin on the swan boats in the lake at the Boston Public Gardens in Boston Common, and plan a stop at the New England Aquarium and Museum of Science too.
Cozumel is considered one of the Western Hemisphere's top diving destinations, and for those who want to explore this spectacular underwater world without shelling out an arm and a leg, El Cozumeleno, facing the Caribbean Sea directly on a white sand beach, is an affordable all-inclusive resort that can help make that a reality. The rooms are no-frills, but you'll probably be spending most of your time in the water, diving, swimming and snorkeling. There are five swimming pools too, including one with the swim-up bar.
Our mission at TravelGuidesFree.com is to put the world you want to visit at your fingertips with quick and easy access to maps, travel tips, local discounts, up to date information and the expert advice found in our offered brochures. Many of our guides are available for instant download, or you can choose to have the guides and brochures mailed to you at no cost. Get the most fun out of your vacation with free travel guides.
When is the best time to go? You will be less limited with a baby or a toddler because they don't yet go to school, allowing you to plan a trip in September or early May when places are less crowded and room rates are lower. If you have older children that are in school, you will need to get away during their school holidays like spring break and summer. During the summer season, most beach destinations are quite crowded while cities tent to be emptier and a good choice as vacations for kids. If you have a teenager who is learning about the U.S. history, take her to Washington D.C. and spend a few days at the Smithsonian Museums.
If you're located on the West Coast, this year is one of the most affordable times to head to Tahiti. Why? This May, French budget airline Frenchbee launched non-stop service from San Francisco (SFO) to Tahiti (PPT). Searches for summer airfare yield results well under $1,000 round-trip, which is unheard of for this exotic destination. Travel in August to take advantage of fares under $750 round-trip. United will also fly directly to the South Pacific islands starting in October of this year, meaning prices will continue to be competitive through the fall.
CheapOair makes it easy to find and book travel packages at great prices. Now you can save even more by booking your flight, hotel, and car rental together. CheapOair works closely with top travel brands to ensure that you get the best vacation deals possible. We offer cheap vacations & packages to the most sought after destinations around the globe. From all-inclusive vacations to kid friendly destinations, romantic and leisure travel, to name a few.


text:
Looking to escape the hectic life 1116 Johnson's Branch Rd. features a well- kept Ranch Style Home in a quiet setting beside a bubbling brook that backs up to pure nature. Five generations of the same family called this location home. Pursue gardening, walking the trails or just relaxing in the back yard. There are ample outbuildings for tools and...28.68 Acres : $84,000
Home With Land in Bandy, VA
Bandy : Tazewell Co : Virginia