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While the term "whore" is a bit incendiary, in my estimation it is quite accurate and justified.
Whore would imply they are doing it for money. I think they do it for "love". Love of Kerry, love of the dems and love of the jihadists.
So I guess since they are not doing it for money and they are doing it for love, that would imply a relationship. A long-term relationship of over 40 years. I think that qualifies them for a common law marriage.

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Blue Cross and Blue Shield of Alabama says it is laying off four percent of its work force because of the downturn in the economy.
The company said Thursday the 151 job cuts would be mostly in the Birmingham area where most of its 3,800 statewide employees work.
The company offered early retirement to employees earlier this year and some took that option last month.


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Watch: British Film Industry Seeks Better Asia Ties
The British Academy of Film and Television Arts, better known as BAFTA, is holding a series of bridge-building events this week in Hong Kong. BAFTA chief executive Amanda Berry spoke to the Journal about her plans.
Follow WSJ Asia on Twitter @WSJAsia.


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With Instructables you can share what you make with the world, and tap into an ever-growing community of creative experts.
This is an easy and cheap Valentines Day decoration sure to add a little love to you room.
Sheet of pink felt Sheet of white felt Small heart shaped cookie cutter Medium heart shaped cookie cutter pencil scissors pink thread white thread needle
Using the small cookie cutter as a stencil trace hearts onto white felt. Using the medium cookie cutter trace hearts on the pink felt. How many depends one ...
For this project there is a wrong side and a right side of the felt. The wrong side of the felt is the side that you traced the ...
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The hotel itself was very lovely and the food in the restaurant was absolutely delicious.Our room was very clean and perfect for the two of us.
Unfortunately, what let the hotel down was the health club. Although the lady doing my treatments was very nice and chatty, the result was disappointing. On the advertisement for this deal the picture was actually of a different swimming pool in a different Barcelo hotel, this was very misleading. The swimming pool at the Oxford hotel was tiny and described by staff as a splash pool. Needless to say I wouldn't consider this a spa break! We also decided to have breakfast in our room which was cold and generally not very nice.
We had a lovely time and the staff were very helpful and friendly but unfortunately the health club/spa was dated and disappointing. I wouldn't return to this hotel for a spa break but if you were visiting Oxford and needed a place to stay then this would be a good choice. Oxford is easily accessible and we found our way around with ease.
All together we had a lovely time but it was disappointing in some areas.
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focoelho.com opened on 20.9.2010 and this domain is 5 years, 11 months old. We see that focoelho.com is using Google Adsense to monetize and , 364132 Alexa Rank and Country rank shows us how good and useful this site is.It is well known webmasters care about W3 Validator and fortunately W3 didn't find any error and warning on focoelho.com. It is important for every website to open quick and be smooth while surfing. We see this site opens in 2369 milliseconds and it isn't a good score at all, you can make your site faster by compressing your scripts and stylesheets. focoelho.com registered under UNIVERSO ONLINE S/A (UOL) and Its nameservers are ns1.focoelho.com and ns2.focoelho.com.On our researches we see focoelho.com gets visitors with these words : focoelho fatos enoticias, menina nua, telexfree, focoelho, focoelho pendencias 29 03 13, feliz dia das mães, cabuloso menina que morreu no hopi hari. This website doesn't have any keyword, we think they should put at least one or two keywords. We see focoelho.com doesn't have DMOZ record that is why we don't think this site is secure to surf but since DMOZ wants money to add your site to Dmoz we can't say this site is 100% secure or not.We see that your website gets most of the users with these missed types;cocoelho.com, fcoelho.com, f0ocoelho.com, fooelho.com, fodcoelho.com, focelho.com, foc0oelho.com, focolho.com, focodelho.com, focoeho.com,
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Does anybody have Insectophobia?I have it since I remember myself. I thought it's common but I never met anyone who has it...
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14 Cygnet Terrace Kingston Park SA 5049
Contact AgentNeed a home loan? Just crunching the numbers for you...
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14 Cygnet Terrace Kingston Park
Looking for style? Walk to the beach!
Last days to purchase at this reduced price $750,000!
Rare opportunity to acquire a beloved family home on a large allotment in the fantastic seaside location of Kingston Park that has not been available since 1978! Move in and enjoy this lovely architecturally designed ranch style home or perhaps secure it as a rare investment or development opportunity (Subject to Council Consent).
Significant features of this property are;
Large allotment with development potential
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Fabulously high ceilings, glass walls and abundant natural light
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Rent Sex in the Heartland 1st edition today, or search our site for other textbooks by Beth L. Bailey. Every textbook comes with a 21-day "Any Reason" guarantee. Published by Harvard University Press.
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|Publication number
|Publication type
|Application number
|Publication date
|Jun 1, 2004
|Filing date
|Feb 28, 2001
|Priority date
|Feb 29, 2000
|Fee status
|Also published as
|Publication number
|Matthew D. Phaneuf, Donald J. Dempsey, William C. Quist, Frank W. LoGerfo
|Original Assignee
|Biomod Surfaces, Beth Israel Deaconess Medical Center
|Export Citation
|BiBTeX, EndNote, RefMan
|Patent Citations (13), Non-Patent Citations (26), Referenced by (8), Classifications (21), Legal Events (5)
|External Links: USPTO, USPTO Assignment, Espacenet
This application claims priority from U.S. Ser. No. 60/186,154, which was filed on Feb. 29, 2000.
This invention was made with government support under a grant entitled DEVELOPMENT OF A BIOLOGICALLY-ACTIVE VASCULAR GRAFT/1R41HL63511-01A1 awarded by the National Heart, Lung, and Blood Institute through a Small Business Technology Transfer Research Program. The government has certain rights to the invention.
This invention relates to biocompatible devices and the methods and materials used to make them. More particularly, the invention relates to synthetic vascular grafts.
Synthetic vascular prostheses have been widely used in clinical medicine as replacements and bypasses for large, medium, and small vessels in human patients. These prostheses are often used when the patient lacks adequate autogenous replacement tissue due to prior chemotherapy, previous harvesting, phlebitis, or other vascular pathologies.
Vascular grafts of medium (6-8 mm) and small (<5 mm) internal diameter are primarily utilized in peripheral regions of the body and appendages. Despite recent advancements in the materials used to make vascular grafts, medium and small diameter grafts continue to have unacceptably high failure rates when used in the clinical setting. The major complications associated with these grafts include: (1) structural and mechanical degradation (Hanson, S. R. In Cardiovasc. Pathology 157S-165S, Harker, L. A., et al. ed., Elsevier Science Publishing Co. Inc., New York, N.Y. (1993)), (2) acute thrombosis and thromboembolic phenomenon (Fyfe, B., et al. Cardiovasc. Path. 2:187 (1993)), and (3) incomplete, unregulated, or inappropriate cellular healing (Kaboda, K., et al. J. Thorac. Cardiovasc. Surg. 103:1059 (1992)). Failure of prosthetic arterial grafts can be grouped into three categories: acute, delayed, and late. An acute failure (occurring within hours or days after implantation) is generally the result of reduced blood flow through the luminal surface of the graft, resulting in increased activation of the coagulation cascade with subsequent thrombosis or thromboembolic phenomenon occurring (Hanson, S. R. In Cardiovasc. Pathology 157S-165S, Harker, L. A., et al. ed., Elsevier Science Publishing Co. Inc., New York, N.Y. (1993)). A delayed failure (occurring within weeks or months after implantation) is generally caused by an incomplete endothelial cell lining of the graft surface, resulting in uncontrolled vascular smooth muscle cell proliferation (LoGerfo, F. W., et al. Ann. Surg. 197:479 1983). Late graft failure (occurring within years after implantation) is infrequent and most often due to progression of atherosclerosis in the inflow or outflow vessels.
Expanded polytetrafluoroethylene (ePTFE) is currently one of the most widely used materials for vascular grafts. See, e.g., U.S. Pat. Nos. 4,187,390 and 3,953,566. However, the chemical structure of ePTFE is extremely rigid, thereby creating a mechanical mismatch at the interface between the native artery and the graft. Additionally, surface modification of ePTFE grafts is generally not possible due to the inertness of the polymer.
Polyethylene terephthalate (polyester or Dacron™) vascular grafts, which have better mechanical (i.e. stretching) and handling (i.e. suturing) properties than ePTFE grafts, have had limited use. These grafts have a porous graft matrix that is typically sealed with proteins purified from another species, e.g. porcine, bovine, etc., that are randomly cross-linked by fixative agents such as glutaraldehyde and formaldehyde. These protein-coated surfaces help to "mask" the graft from immune response. However, they have numerous adverse effects in vivo, including platelet adhesion and activation with the release of growth factors and pro-thrombotic molecules, and are rapidly desorbed, potentially re-exposing the biomaterial surface.
Due to the problems associated with conventional synthetic vascular grafts, they are generally unsuitable for smaller diameter vascular reconstructions. Thus, there remains a need to develop biocompatible synthetic vascular prostheses that have physical and chemical properties that more closely approximate those of autogenous blood vessels. In particular, there is a need to develop vascular grafts suitable for use in medium and small diameter arterial reconstructions.
The present invention features a polyether or polyether/carbonate based urethane polymer that contains functional groups (e.g. carboxylic acid groups) which are capable of serving as anchor sites for protein binding. The polymer is prepared using a process that includes the following two steps: (1) forming a diisocyanate terminated prepolymer, based on a polyether or polyether/carbonate glycol that has a molecular weight between 200-3,000 Da (preferably about 1000 Da), and a diisocyanate having the general structure OCN—R′—NCO, wherein R′ is a hydrocarbon that may include aromatic or non-aromatic structures; and (2) chain extension using a dihydroxy carboxylic acid, for example, 2,2-bis(hydroxymethyl)-propionic acid (DHMPA).
The invention also features a biocompatible device that has been sealed with the polyether or polyether/carbonate based urethane polymer. The biocompatible device can be, for example, a polyethylene terephthalate (polyester or Dacron™) vascular graft or other polymeric base material. The surface properties of the graft can be modified with biologically active proteins in order to emulate certain natural properties of native vessels, thereby improving graft patency and healing. For instance, antithrombin (recombinant hirudin) or other anti-clotting agents, thrombolytic agents (e.g. streptokinase, urokinase, tPA, pro-urokinase, etc.), and mitogenic agents (e.g. vascular endothelial growth factor) or other growth promoting substances, or inhibitors (e.g. γ-interferon) can be linked to the surface of the graft.
In another aspect, the invention provides a technique for sealing a vascular graft, such as a polyethylene terephthalate vascular graft, with polyurethane using an inward/luminal perfusion system. The perfusion system includes a flow chamber which has inflow and outflow fixtures and a hollow inner mandrel. The system also includes a Y-fitting that is connected to the flow chamber and a peristaltic pump via hollow plastic tubing. The Y-fitting is also connected to a container holding a polyurethane sealant solution.
FIG. 1 is a diagram of a perfusion system adapted to incorporating PEU-COOH throughout the wall of a vascular graft.
FIG. 2 is a bar graph showing water permeation data for selected vascular grafts.
FIG. 3 is a picture of the lumenal surface and capsular surface of a Dacron™ graft sealed with a PEU-COOH coating.
FIG. 4 is a bar graph showing 125I-CSA binding data for selected vascular grafts.
The invention features a biocompatible device which has been coated or sealed with a polyether or polyether/carbonate based urethane polymer. The polyurethane compound of the invention contains functional groups (e.g. carboxylic acid groups) which are capable of serving as anchor sites for protein binding. This polyurethane possesses more compliant mechanical properties (i.e. elasticity) than previously utilized polycarbonate-based urethanes.
The biocompatible device of the invention is intended to contact cells, biological fluids, or preparations derived from cells. In one embodiment, the biocompatible device is a vascular graft prosthesis. Vascular grafts of the invention are preferably biodurable, non-thrombogenic, chemically durable, resistant to infection or formation of microbial plaques, easy to implant, and possess appropriate elastic properties.
Biocompatible materials suitable for use in the vascular grafts of the invention can be any materials that do not activate coagulation or inhibit cellular healing. The material should be sufficiently malleable so that it can form the appropriate geometry, but also have sufficient tensile strength to endure rigorous circulation throughout the vascular tree. The biocompatible material should be able to be sterilized, for example, by gamma radiation. The biocompatible materials useful in the present invention include, but are not limited to, polyethylene terephthalate (Dacron™ or polyester), nylon, polyurethane, Kevlar™, polyethylene, polypropylene, silicons, and combinations thereof.
Standard Dacron™ vascular grafts are predominantly employed for large-diameter arterial reconstructions (i.e., internal diameter (ID) greater than 9 mm), such as thoracic or abdominal aorta reconstructions. A majority of these grafts are sealed with cross-linked collagen (e.g. HEMASHIELD™) in order to prevent pre-clotting the graft interstices with the patient's blood. This sealing procedure often creates a highly thrombogenic surface. Blood flow through these larger arteries is significantly higher than other areas within the peripheral vascular tree (e.g., the iliac and femoral arteries), therefore grafts implanted at these sites generally have greater than 90% patency rates. Implantation of conventional Dacron™ grafts in peripheral or medium-diameter arteries (i.e., internal diameter between 6-8 mm) results in a significant reduction in patency (20-40%) (see, e.g., Comerota, A. J., et al. "Graft thrombosis and thromboembolic complications" in Vascular Surgery, 4th Ed., Rutherford, R. W. ed., W. B. Saunders Co., Philadelphia (1995)).
Prosthetic grafts made from ePTFE are used for both large and medium-diameter arterial reconstructions. No difference in patency rates between Dacron™ and ePTFE grafts in large-diameter implants has been demonstrated. In medium-diameter reconstructions, however, ePTFE has slightly higher patency than Dacron™. In general, neither of these types of graft material are used clinically for small-diameter arterial grafting (i.e., internal diameter of less than 5 mm) due to poor patency rates (less than 20% patency within the first year).
In a preferred embodiment, the biocompatible device of the present invention is a polyethylene terephthalate (Dacron™) vascular graft. The graft is sealed with polyurethane preferably using an inventive sealing technique, with permeation controlled by the methodology. The final composite graft of the invention has permeation values comparable to that of a protein-sealed vascular graft. The preferred polyurethane sealant has functional groups (e.g. carboxylic acid groups) within the polymer backbone to which proteins can be covalently attached. The functional groups on the graft surface are accessible to protein binding, with less non-specific protein adhesion than a standard Dacron™ prosthesis. The polyurethane-sealed graft of the invention has good handling characteristics, self-sealing properties, and healing characteristics comparable to a standard protein-sealed Dacron™ prosthesis, but without the adverse effects associated with conventional protein-sealed grafts. These improved characteristics enable the graft to be used not only in large-diameter vascular reconstructions, but also in medium and small-diameter reconstructions.
Studies on the mechanisms of prosthetic arterial graft failure have revealed that all biomaterials are excluded from direct blood interaction within minutes of establishing blood flow by an amorphous pseudointima composed of platelets, fibrin, fibrinogen, and serum proteins. LoGerfo, F. W., et al., Ann. Surg. 197:479 (1983). Thus, it is desirable to have a biomaterial surface which will alter pseudointima composition and formation. Furthermore, biomaterials inter-positioned in the vasculature must address two key components of vascular graft biology: (1) activation of the coagulation cascade and (2) incomplete cellular healing. Since the polyurethane sealant of the present invention possesses functional groups which permit covalent linkage of protein, the surfaces of implants sealed with this polyurethane can be designed so that selected biologically-active proteins can be immobilized in order to localize the beneficial effects directly on the material surface. Thus, both antithrombin and mitogenic factors can be covalently bound to a vascular graft surface in order to prevent acute thrombosis and potentiate cellular ingrowth across the graft. In a preferred embodiment, the biocompatible Dacron™ vascular graft of the invention possesses both surface bound antithrombin and mitogenic properties via covalent linkage of the potent antithrombin agent rHir (to inhibit thrombin activity) and the endothelial cell specific growth factor VEGF (to enhance endothelial cell proliferation) to the polyurethane sealant.
Polyurethanes have unique mechanical and biological properties (i.e., inherent toughness, flexibility, excellent biocompatibility) that make them ideal for use in a wide variety of implantation devices. Polyurethanes are used in many biomedical applications, including ventricular assist devices, access shunts, vascular grafts, and stents. Polyurethanes can be divided into three major groups depending on the choice of macroglycol used to prepare the polymer: polyester-based polyurethanes, polyether-based polyurethanes, and polycarbonate-based polyurethanes. Polycarbonate-based urethanes are stiffer and less compliant than polyether-based polyurethanes with equal hard segment concentration. This is believed to be due to the rotational stiffness imparted by the carbonate linkage (O—C═OO) versus the freedom of the ether linkage (C—O—C). In order to maintain a wide latitude for formulation development (i.e. increase hard segments, more functional groups for attachment) while preserving a narrow range of compliance, it is desirable to utilize more compliant ether macroglycol formulations or ether/carbonate macroglycol (CAS Registry Number 92538-66-4) formulations.
The biostability of polyurethanes has been vigorously studied. See, e.g., Stokes, K., Advances in Biomedical Polymers, Proc. Natl. Acad. Sci., Plenum Press, N.Y. (1987). Environmental Stress Cracking (ESC) has been determined to be the main complication associated with implantation of polyurethanes. The two primary factors contributing to ESC of polyurethanes are (1) the presence of an applied strain (must be greater than 100%) and (2) the presence of ether linkages. The elimination of either of these factors will stabilize the polymer against ESC. The first factor can be eliminated by ensuring that minimal strain is present in the final product. This can be accomplished by manufacturing parts using a solution coating process. Annealing, the process of solvent evaporation at elevated temperatures, may also be used since annealed polymers generally do not exhibit ESC in vivo. Zhao, Q. et al., J. Biomed. Mater. Res. 29:467 (1995). Thus, solvent processing alone can largely eliminate ESC.
The presence of ether linkages also effects ESC of polyurethanes. Both commercial polycarbonate and polyether urethanes contain ether linkages. In polycarbonate urethanes applicable for vascular uses (Shore hardness range of about 75 to 90 Å) the percent of ether linkages is low (4 to 12%) and thus less susceptible to ESC. Unstabilized polycarbonate urethanes have been shown to be susceptible to ESC in vivo. Therefore, in long-term clinical applications, chemical and/or other methods of stabilization may be needed if the ether linkages cannot be totally eliminated.
ESC initiates as surface phenomena and various approaches have been employed to slow the onset. These include the use of antioxidants, preparation of copolymers such as urethane/silicone polymers in attempts to mask the ether group, and formulating morphological changes to exclude the ether group from the surface. See, e.g., Zhang, Z., et al., Biomaterials 16(5):369 (1995), and Ward, R. S., et al., "The effects of phase separation and endgroup, chemistry on in vivo biostability of polyurethane." Trans ASAIO Meeting, Washington, D.C., Lippincott-Raven, Philadelphia, Pa. (1996). Recent efforts using vitamin E as an antioxidant in polyether urethanes have shown that vitamin E prevents ESC in vivo. Collier, T., et al., J Biomed. Mater. Res. 41(2):192 (1998). This antioxidant offers many desirable characteristics; it is biocompatible, it has low water solubility (less extractable by the blood), and it has been shown through its many years of use as a commercial polymer stabilizer to be thermally stable. Thus, vitamin E is a good choice as an antioxidant and can be used in the solvent drying processes.
It is believed that ESC is caused by the extraction of a hydrogen that is bonded to the carbon in the alpha position to the oxygen atom. Therefore, synthesizing a polyurethane that excludes this group from the biologic interface through morphological changes is desirable and should give additive if not synergistic (use of vitamin E) protection against ESC. This makes polyether urethane a good choice because of its greater latitude in formulating. In a given compliance (stiffness) range, the hard segment, diisocyanate/short chain extender can be increased 20% more for the polyether urethane than it can for the polycarbonate urethane counterpart. Increasing the hard segment while maintaining the same compliance range provides a two-fold advantage. First, the concentration of the chain extender that contains the functional carboxylic acid groups is increased allowing for greater biological binding. Second, increasing the hard segment necessarily reduces the more susceptible soft segment. More importantly, the surface morphology for a polyurethane having a hard segment greater than 50% is exclusively urethane or urea bonds. These have been proven stable to the biological environment as shown by the absence of ESC in polyether urethane of 55D hardness. Schubert, M. A., et al., J. Biomed. Mater. Res. 32:493 (1996).
The polyether or polyether/carbonate based urethane of the present invention contains functional groups, such as carboxylic acid groups, which can be used as anchor sites for protein binding. This ionic polyurethane can be used as a sealant to seal a wide variety of biocompatible devices and implants, including polyethylene terephthalate (polyester or Dacron™) vascular grafts, as well as other types of vascular grafts. It can seal the graft interstices, maintain the physical properties of the Dacron™ scaffolding, and permit covalent linkage of antithrombin (recombinant hirudin or rHir) or other anti-clotting agents, thrombolytic agents (e.g. streptokinase, urokinase, tPA, pro-urokinase, etc.), and mitogenic agents (e.g. vascular endothelial growth factor or VEGF) or other growth promoting substances (e.g. basic or acidic fibroblast growth factor, platelet-derived growth factor, etc.) or inhibitors (e.g. γ-interferon). Surface modification with biologically active proteins can, in part, emulate some of the natural properties of native vessels, thereby improving graft patency and healing. Inhibition of the enzymatic chemotactic and mitogenic properties of thrombin via surface bound anti-clotting factors can significantly reduce blood product formation and maintain anastomotic smooth muscle cells in the quiescent state, thereby preventing the formation of anastomotic intimal hyperplasia. Covalent linkage of growth factors permits complete endothelialization of the graft surface by both trans-anastomotic and trans-membrane (through the remaining residual porosity) cellular migration.
The polyether or polyether/carbonate based urethane polymers of the invention can be obtained by first forming a diisocyanate terminated prepolymer, based on a polyether glycol or a polyether/carbonate glycol having a molecular weight between 200-3,000 Da (preferably between 500-2,500 Da; most preferably about 1000 Da), and a diisocyanate having the general structure OCN—R′—NCO, wherein R′ is a hydrocarbon that may include aromatic or non-aromatic structures, including aliphatic and cycloaliphatic structures. This is followed by chain extension using a dihydroxy carboxylic acid, for example, 2,2-bis(hydroxymethyl)-propionic acid (DHMPA). Polytetramethylene ether glycol (PTMEG 1000) is the preferred polyetherglycol, and the preferred polyether/carbonate macroglycol is polyetherpolycarbonatediol 1000 molecular weight.
The preferred isocyanates include methylene diisocyanate, 4,4′-methylene bisphenyl isocyanate, 4,4′-diphenylmethane diisocyanate (MDI), and hydrogenated methylene diisocyanate (HMDI). Other suitable isocyanates include, but are not limited to, hexamethylene diisocyanate and the toluene diisocyanates, such as 2,4-toluene diisocyanate and 2,6-toluene diisocyanate, 4,4′-tolidine diisocyanate, m-phenylene diisocyanate, 4-chloro-1,3-phenylene diisocyanate, 4,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,10-decamethylene diisocyanate, 1,4-cyclohexylene diisocyanate, 4,4′-methylene bis (cyclohexylisocyanate), 1,4-isophorone diisocyanate, 3,3′-dimethyl-4,4′-diphenylmethane diisocyanate, 1,5-tetrahydronaphthalene diisocyanate, and mixtures of such diisocyanates. Also included among the isocyanates suitable to this invention are specialty isocyanates containing sulfonated groups for improved hemocompatibility and the like.
A preferred solvent for this process is dimethyl acetamide (DMAC). Other suitable solvents that can be used in this process include, but are not limited to, DMF, THF, cyclohexanone, m-pyrol, etc. Stannous octoate is preferably used as a catalyst. Other catalysts may be used, such as dibutyl tin dilaurate, or generally an organo tin catalyst which is non-toxic and readily hydrolyzes.
The polyether or polyether/carbonate based urethane polymers resulting from the preferred method of synthesis contain carboxylic acid groups within the polymer backbone (PEU-COOH), and have more compliant mechanical properties (i.e. elasticity) than polycarbonate-based urethanes. The synthesis method can be modified to produce a urethane polymer having different functional groups within the polymer backbone. This can be accomplished by, for instance, chain extension with amine groups or photoactive groups.
The invention also features a method of sealing a vascular graft with polyurethane using a modified perfusion system. The vascular grafts of the present invention can be made according to the following steps. First, the graft, preferably a Dacron™ double velour vascular graft, is scoured and washed. The graft is then hydrolyzed, rinsed and dried. Knitted or woven grafts may be used. In a preferred embodiment, the grafts are warp knit (Meadox Medicals, Oakland, N.J.). Examples of other suitable grafts which are commercially available include weft knit, reverse locknit, locknit, or sharkskin grafts.
In one embodiment of the invention, the PEU-COOH is incorporated throughout the wall of the graft using an inward/luminal perfusion system. An example of this perfusion system is shown in FIG. 1. The system includes a flow chamber 1 having an inflow fixture 2 and an outflow fixture 3 in order to circulate polyurethane throughout the system. The flow chamber also includes a porous hollow inner mandrel 4 attached to tubing connectors via micro-glan clamps.
The system also includes a Y-fitting 5. One part of the Y-fitting 5 is connected to the outflow connector 3 of the flow chamber 1 with hollow plastic tubing, preferably inert Tygon tubing (�″ ID). Another part of the Y-fitting 5 is connected to a peristaltic pump 6, which in turn is connected to the inflow connector 2 of the flow chamber 1. The final part of the Y-fitting is connected to a container 7 holding the PEU-COOH solution. The percent solids in solution may vary from about 1% to about 10%, preferably between 5-7.5%.
The hydrolyzed graft is fitted to the mandrel and tied (e.g. via 2-0 silk), followed by insertion into the flow chamber of the perfusion system. After perfusion, the graft is removed from the flow chamber and air dried, preferably at about 60� C. for approximately 1.5 hours. The graft is then subjected to infusion to uniformly coat the luminal surface. The graft is infused with a solution of PEU-COOH using a programmable infusion system. Again, the percent solids in solution may vary from about 1% to about 10%, preferably between 5-7.5%. After perfusion, the graft is air-dried at about 60� C. for approximately 1.5 hours. This inward/luminal perfusion technique results in a PEU-COOH sealing of the Dacron™ graft (PEU-D). The graft has good flexibility and kink resistance, with PEU-COOH coated evenly on both the lumenal and capsular surfaces of the graft. See FIG. 3.
The surface of the vascular graft of the invention can be modified with biologically active proteins in order to emulate some of the natural properties of native vessels, thereby improving graft patency and healing. For example, the enzymatic, chemotactic, and mitogenic properties of thrombin can be inhibited by surface bound rHir (recombinant hirudin). This inhibition can significantly reduce blood product formation and maintain anastomotic smooth muscle cells in the quiescent state, thereby preventing the formation of anastomotic intimal hyperplasia. rHir has been shown to have potent antithrombin activity when covalently immobilized onto a Dacron™ surface (see, e.g., Phaneuf, M. D., et al., Biomaterials 18(10):755 (1997) and Berceli, S. A., et al., J. Vasc. Surg. 27:1117 (1998)) or to another biomolecule (see, e.g., Phaneuf, M. D., et al., Thromb. Haemostas. 71(4):481 (1994)). In addition, covalent linkage of VEGF (vascular endothelial growth factor) may permit complete endothelialization of the graft surface by both trans-anastomotic and trans-membrane (through the remaining porosity) cellular migration. Techniques for binding growth promoting factors to biocompatible materials are described in U.S. Ser. No. 09/139,507 entitled "Growth-Promoting Biocompatible Substances and Methods of Use Thereof," and in Kubaska, S. M. III, et al., Surgical Forum 49:322 (1998), which are herein incorporated by reference.
Covalent linkage of protein to a biomaterial surface in order to create a "basecoat" layer has numerous beneficial advantages. Non-specific or covalent attachment of a protein coating can "passivate" a surface that is relatively thrombogenic, thereby decreasing adhesion of blood products such as platelets, red blood cells, and fibrinogen. Rumisek, J., et al., Surgery 105:654 (1989). Proteins incorporated as a basecoat layer can be used as a "scaffolding" in order to promote a specific response such as linkage of RGD peptides to promote cell adhesion. Lin, H. B., et al. J. Biomed. Mater. Res. 28:329 (1994). Additionally, increasing the angstrom distance between a biologically-active molecule and the surface via polyethylene oxide groups can reduce steric hindrance on the target molecule, thereby maintaining activity. Park, K. D., et al., J Biomed. Mater. Res. 22:977 (1988).
Covalent linkage of a protein "basecoat" layer can serve as the spacer between rHir/VEGF and the biomaterial surface. In one embodiment of the invention, albumin is used as the basecoat moiety. Albumin, which is in natural abundance in circulating blood, has numerous beneficial results in vitro and in vivo. Kotteke-Marchant, K., et al., Biomaterials 10:147 (1989) and Phaneuf, M. D., et al., J Applied Biomater. 6:289 (1995). Utilization of a basecoat layer permits significant amplification of potential binding sites for secondary protein attachment via heterobifunctional crosslinkers, creating a biomaterial surface with distinct properties for a specific application and has been shown to have numerous binding sites for rHir. Phaneuf, M. D., et al. ASAIO J. 44:M653 (1998) and Phaneuf, M. D., et al., Biomaterials 18(10):755 (1997). Examples of other basecoat proteins include, but are not limited to, collagen and fibronectin. Alternatively, the basecoat may be synthetic, such as, for example, a Lys-Tyr moiety or polyethylene oxide.
One of the advantages of the present invention is a reduction in the inflammatory response that often results from the implantation of a synthetic device into a patient. In particular, implantation devices made of Dacron™ often elicit an inflammatory response, which may interfere with the overall healing of the graft surface. In contrast, non-extruded polyether-based urethane generally elicits a minimal inflammatory response compared to that of Dacron™ fibers due to antioxidants incorporated into the polymer solution. Thus, when the polyurethane of the invention is used to seal Dacron™ grafts it helps to "mask" the Dacron™ scaffold from immune response.
The Dacron™ vascular grafts of the invention are useful as replacements or bypasses in large and small diameter clinical arterial reconstructions. The invention is also useful as a hemodialysis access graft due to the sealing properties of the polyurethane, or as a sealant for the Dacron™ cuff sewn onto heart valves. Furthermore, the sealing technique of the present invention can be used to seal woven grafts, thereby preventing fraying upon cutting, a major problem when using such structures clinically.
The features and other details of the invention will now be more particularly described and pointed out in the examples. It will be understood that the particular embodiments of the invention are shown by way of illustration and not as limitations of the invention. The principle features of this invention can be employed in various embodiments without departing from the scope of the invention.
A biodurable polyether-based polyurethane compound containing carboxylic acid groups was synthesized by a two step procedure. The first step involved the formation of diisocyanate terminated prepolymer, based on 1000 Da (molecular weight) polytetramethylene ether glycol (PTMEG 1000) and 4,4′-diphenylmethane diisocyanate (MDI). This was followed by chain extension by 2,2-bis(hydroxymethyl)-propionic acid (DHMPA). Dimethyl acetamide (DMAC) was used as the solvent and stannous octoate as a catalyst.
A 1000 nominal molecular weight polyether polyol (117.0 g containing 0.117 moles−hydroxyl content=112.2 mg KOH) and 62.5 g (0.25 moles) of MDI was charged to a reaction kettle and stirred for 1.5 hours at 75� C. under a dry, inert N2 atmosphere. DMAC (502.9 g) was then added and reaction temperature lowered to 65� C. with constant stirring for an additional 1 hour. DHMPA (18.8 g, 0.14 moles) and five drops of stannous octoate were added to the reaction mixture and the temperature adjusted to 60� C. This temperature was held for an additional 2 hours, then the reaction mixture was slowly cooled to ambient temperature while mixing continued. The resulting solution, approximately 28% weight, was transferred into a wide-mouth jar and stored under a dry nitrogen blanket. This polymer was designed to contain approximately 3.2% (weight) of reactive carboxyl groups. Films (0.1 mm) were then cast from the 15% solids solution onto release paper to grossly evaluate the presence of carboxylic acid groups via methylene blue uptake, and to macroscopically assess physical parameters.
In a similar fashion, a Biodurable poly(ether/carbonate)-based polyurethane containing carboxylic acid groups was synthesized by the two step procedure utilizing: 1) formation of diisocyante terminated prepolymer, based on 1000 Da (molecular weight) polyetherpolycarbonatediol (CAS Registry Number 92538-66-4) and 4,4′-diphenylmethane diisocyante (MDI) followed by 2) chain extension by 2,2-bis(hydroxymethyl)-propionic acid (DHMPA). Dimethylacetamide (DMAC) was used as the solvent and stannous octoate as catalyst.
A 1010 nominal molecular weight polyetherpolycarbonatepolyol (118.3 g) containing 0.117 moles (hydroxyl content=111.0 mg KOH) and 64.25 g (0.257 moles) of MDI was charged to a reaction kettle stirred for 1.5 hours at 75� C. under a dry, inert N2 atmosphere. DMAC (517.8 g) was then added and reaction temperature lowered to 65� C. with constant stirring for an additional 1 hour. DHMPA (18.8 g, 0.14 moles) and five drops of stannous octoate were added to the reaction mixture and the temperature adjusted to 60� C. This temperature was held for an additional 2 hours, then the reaction mixture was slowly cooled to ambient temperature while mixing continued. The resulting solution, approximately 28% weight, was transferred into a wide-mouth jar and stored under a dry nitrogen blanket. This polymer was designed to contain approximately 3.2% (weight) of reactive carboxyl groups. Films (0.1 mm) were then cast from the 15% solids solution onto release paper to grossly evaluate the presence of carboxylic acid groups via methylene blue uptake, as described under the preceding chemical characterization section, and to macroscopically assess physical parameters.
The processes resulted in either a polyether (PEU-COOH) or a polyetherpolycarbonate (PEU-COOH)-based urethane polymer with carboxylic acid groups. Both of which possess more compliant mechanical properties (i.e., elasticity) than previously utilized polycarbonate-based urethanes. Carboxylic acid groups were also determined to be accessible within the polymer structures via methylene blue uptake (data not shown).
Graft Preparation
Knitted Dacron™ double velour vascular grafts (100 cm length) were scoured in a 1 L Tween 20/sodium carbonate solution at 60� C. for 30 minutes followed by a distilled water wash at 60� C. for 30 minutes. Grafts were then hydrolyzed by exposing the graft to 1% sodium hydroxide at 100� C. for 30 minutes. The grafts were rinsed with distilled water and dried at 80� C. for 1 hour. After drying, the grafts were cut into segments (15 cm) that were used for each perfusion.
Inward/Luminal Perfusion System
A perfusion system shown in FIG. 1 was used in order to incorporate PEU-COOH (as prepared in Example 1) throughout the wall of the graft. This system included a 60 ml polyethylene chamber with inflow and outflow fixtures in order to circulate polyurethane throughout the system. Connected to the chamber was a porous, hollow inner polyethylene mandrel attached to 6 mm tubing connectors. The hydrolyzed graft segment was connected to this fitting via 2-0 silk and inserted into the flow chamber through a pre-fit seal secured with Teflon tape. A cover was placed over the top of the chamber in order to stabilize the upper connector. Inert Tygon tubing (�″ ID) was fitted over the upper (withdrawal) connector, followed by attachment to a Y-fitting. One part of the Y-fitting was connected to a Harvard Apparatus peristaltic pump that continued onto the side connector (inlet feed) of the chamber, thereby completing the perfusion loop. Tygon tubing was connected to the other part of the Y-fitting which was inserted into a 7.5% solids PEU-COOH solution. The flow rate was 12 ml/min and the system was run for 1 hour. After perfusion, the graft was removed from the chamber with one connector remaining attached and air-dried at 60� C. for 1.5 hours.
The connector/graft segment was then attached to a 60 ml syringe that had an 8 mm connector on the outflow end. The syringe was filled with a 7.5% solids solution of PEU-COOH and placed into a Harvard Apparatus PHD 2000 Programmable Infusion System. The graft was set in a downward position prior to infusion and clamped at the end of the graft in order to uniformly coat the luminal surface. A flow rate of 20 ml/min was employed. Once the graft was filled, the clamp was immediately released. Flow was then permitted to continue unhindered for the remainder of the run. The graft was removed from the system and air-dried at 60� C. for 1.5 hours.
Macroscopically, PEU-COOH sealing of Dacron™ grafts using this inward/luminal perfusion technique resulted in a flexible vascular graft with good kink resistance. Additionally, the PEU-COOH coating was evenly distributed on both surfaces, a significant improvement over previous sealing techniques. There were also no apparent air bubbles trapped within the graft wall.
Physical Characterization
Water permeation for cleaned (CNTRL), HEMASHIELD™, and PEU-D grafts (7.5%/7.5%, 5.0%/7.5% and 5.0%/5.0%) (as prepared in Example 2) was determined using a previously described procedure. Sawyer, P. N., et al., J. Biomed. Mater. Res. 13:937 (1979). Grafts (6 mm, ID) of each material were opened and cut into circular segments (15 cm diameter). A cylindrical reservoir, with a direct water inlet to keep pressure constant, was set to a height of 165 mm to the top of the water column. Polypropylene tubing (�″ ID) was run from the bottom of the reservoir and connected to a T-shaped fitting. One part of the fitting was connected to tubing that was attached to a manometer, permitting accurate determination of pressure directly at the sample/water interface. The other part was attached to the sample chamber. A {fraction (5/16)}″ Tight Right fitting (attached to {fraction (3/16)}″ tubing) was used to hold the test segment in place without applying stretch to the material. The area of material exposed to flow was calculated to be 0.38 CM2 and was constant for all samples. A hemostat was used to maintain stasis between sample changes. Each segment of material was pre-soaked in the apparatus for 1 minute in order to de-gas. All graft segments were exposed to 120 mm Hg pressure. The CNTRL segments, due to the high water permeability, had to begin at 180 mm Hg at stasis in order to maintain pressure constant upon water release. The Hemashield graft segments (cross-linked collagen impregnated) and PEU-D segments were exposed to 120 mm Hg pressure without alteration. CNTRL segments were evaluated for 30 seconds and Hemashield/PEU-D for 60 seconds. Volume was collected in a graduated cylinder and was used to determine ml/min/cm2.
Water permeation by PEU-D grafts sealed with either 7.5%/7.5% (0.44�0.38 ml/min/cm2) or 5.0%/7.5% (13�17 ml/min/CM2) solids had comparable water permeation to collagen cross-linked Hemashield grafts (17�11 ml/min/cm2), as shown in FIG. 2. Water permeation using the 5.0%/5.0% parameters (67�30 ml/min/cm2) was higher than the Hemashield grafts, however, implantation of grafts with permeation values of less than 100 ml/min/cm2 has been performed without bleeding complications. The mean permeation reported for Hemashield grafts was <10 ml/min/cm2, thereby demonstrating the accuracy of the test method. CNTRL segments were essentially ineffective at blocking water permeation (2,717�140 ml/min/cm2), with this value slightly higher than the reported mean permeability of 1,900 ml/min/cm2.
Chemical Characterization
Methylene blue (MB), a cationic dye that has been employed to determine carboxylic acid groups within both Dacron™ and polyurethane (see, e.g., Dempsey, D. J., et al., ASAIO J 44:M506 (1998)), was used to quantitatively and qualitatively assess carboxylic acid content in the PEU-D grafts. A 500 ml stock solution (500 μg/ml) of methylene blue was prepared (80% Purity) in 0.1 M Tris-CL pH 8.0. A working solution of methylene blue was prepared by aliquotting 1 ml of the stock solution and bringing to a total volume of 100 ml with Tris buffer (5 μg/ffil). Segments (0.5 cm) were cut from knitted, 0.5% sodium hydroxide-hydrolyzed (HYD), and 3 PEU-D sealed grafts (n=4/test group). Working MB solution (10 ml) was added to each segment, and incubated for 1 hour. Grafts were removed and placed into wash solution consisting of Tris buffer for one hour. Dye bath and wash solutions were read at 611 nm using Tris buffer as blank. Quantification of carboxylic acid groups within each graft (nmoles/mg) was calculated using standard equations as previously described.
The amount of carboxylic acid groups created on the PEU-D segments (1.04�0.27, 0.92�0.07, and 0.86�0.06 nmoles/mg, respectively) was significantly greater than both HYD (0.43�0.7 nmoles/m g) and CNTRL (0.24�0.05 nmoles/mg) segments, respectively. Microscopic evaluation of methylene Blue-dyed PEU-D grafts revealed a uniform seal that extended throughout the graft wall. Additionally, both surfaces showed comparable PEU-COOH coating, as seen in FIG. 3.
125I-canine serum albumin (CSA) binding versus CNTRL, HYD, and PEU-D segments (3 treatments) was performed to determine basecoat binding. Phaneuf, M. D., et al., Biomaterials 18(10):755 (1997) and Phaneuf, M. D., et al., J Biomed. Appl 12:100 (1997). Graft segments (0.5 cm) were cut and weighed (n=4/test group/condition). One set of each graft type was placed into 5 ml of a 10 mg/ml (50% ethanol) solution of EDC crosslinker. The control segments of each group were placed into 5 ml of 50% ethanol solution. A total of 4 segments/tube were used for all protein binding assays. All segments were reacted for 30 minutes at room temperature on an inversion mixer. Segments were then removed from their respective solutions, shaken to remove excess solvent/crosslinker and placed into 2.4 ml of a 14.8 μM 125I-CSA, radiolabeled. These segments were incubated for 2 hours at room temperature on an inversion mixer. Control and test segments of each were removed and placed into individual test tubes containing 2 ml of PBS with 9% Tween 20. These polyurethane segments were sonicated in an ultrasonic cleaner for 5 minutes. This procedure was repeated 3 times followed by 2 additional washes for 15 minutes, with the wash buffer changed between sonications, in order to remove any weakly adherent 125I-CSA on the segment surface. Segments with non-specifically bound (CNTRL+125I-CSA, HYD+125I-CSA, and PEU-D+125I-CSA) and covalently bound (CNTRL−125I-CSA, HYD−125I-CSA, and PEU-D−125I-CSA) 125I-CSA were then gamma counted. Utilizing the specific activity, the amount of 125I-CSA bound (ng) per weight of graft segment (mg) was determined. Results are shown in FIG. 4.
Non-specific binding of 125I-CSA to HYD segments (115�27 ng/mg) was greater than CNTRL (54�13 ng/mg) and PEU-D (18�3, 13�0.8, and 20�2 ng/mg, respectively) segments, with the PEU-D segments binding the lowest amount of 125I-CSA (FIG. 4). Therefore, PEU coating significantly reduced non-specific protein adhesion. Covalent linkage of 125I-CSA was also greatest in the HYD segments (613�77 ng/mg) as compared to CNTRL (509�36 ng/mg) and PEU-D (103�2, 90�7, and 129�11 ng/mg, respectively) segments. The lower amount of 125I-CSA bound is believed to be attributed to a reduced total surface area by the polyurethane sealant. Reduction in CSA adhesion could result in lowering non-specific binding of other blood products such as fibrinogen, platelets or thrombin that are detrimental to graft patency.
Mongrel canines (25-30 kg) were sedated with acepromazine (0.75 mg/kg), induced with pentothal and maintained on halothane gas (0.5-1.5%). Through a midline incision, the carotid arteries were exposed for a length of approximately 15 cm. Following heparinization (100 units/kg), a 6 mm, 5.0%/7.5% PEU-COOH sealed Dacron™ graft (6 cm length, gamma sterilized) was implanted on one side and a 6 mm 5.0%/5.0% PEU-COOH sealed Dacron™ graft (6 cm length, gamma sterilized) was implanted on the contralateral side. The grafts were re-exposed at 1 week and punctured with a 16-gauge needle to determine the self-sealing properties of the graft. The grafts were then excised and evaluated for patency, gross thrombus and pseudointima formation.
The graft handling properties were comparable in both stiffness and suturing, with a favorable rating from both surgeons. Grafts did soften upon soaking in saline prior to suturing. Needle puncturing of both grafts showed self-sealing of the puncture site within seconds of needle removal. Both grafts were patent at 1 week. Upon macroscopic evaluation, the surface had uniform pseudointima formation, with composition to be determined via histological analysis.
Although the present invention has-been described with reference to preferred embodiments, one skilled in the art can easily ascertain its essential characteristics and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions. Those skilled in the art will recognize or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed in the scope of the present invention.
All publications, patents, and patent applications, mentioned in this specification are herein incorporated by reference.
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|U.S. Classification
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|International Classification
|Cooperative Classification
|European Classification
|Aug 10, 2001
Owner name: BIOMOD SURFACES, MASSACHUSETTS
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:DEMPSEY, DONALD;REEL/FRAME:012062/0221
Effective date: 20010717
Owner name: BETH ISRAEL DEACONESS MEDICAL CENTER, MASSACHUSETT
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:PHANEUF, MATTHEW D.;QUIST, WILLIAM C.;LOGERFO, FRANK W.;REEL/FRAME:012069/0417
Effective date: 20010517
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Effective date: 20080601


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- Report: #421394
Report - Rebuttal - Arbitrate
Complaint Review: IK9 Privacy Matters & IK9 Privacy Plus Fraud Scam
IK9 Privacy Matters & IK9 Privacy Plus Fraud Scamprivacymatters-program.com/ Internet U.S.A.
AP9 Privacy Matters & IK9 Privacy Plus Unauthorized, fraudelent charges to my Credit Card Internet
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The credit card company faxed me a document for me to sign to start the proceedings. The worst of it is I had to close my account and reopen a new one because my account had been compromised. What a pain in the neck. So now I have to wait up to 14 days for them to send me a new card.
Next step is to notify all companies I pay automatically using the card of the change. Bummer.
The worst part is my credit score will take a hit because of this. CRAZZAP!
Someone needs to shut this fraudulent company down. Privacy Matters, what a joke of a name! They steal your privacy so I am sure your lack of privacy matters.
FYI the charges to my account started after I bought a yahoo game online for my computer. I would think that Yahoo would be more secure than that. I bought the game on the 3rd and the next day I took 2 hits with 3 more following.
My advice is to check you credit card statement or bank statement every day to look for fraudulent charges such as these.
Freeport, Kansas
This report was posted on Ripoff Report on 02/07/2009 11:44 AM and is a permanent record located here: http://www.ripoffreport.com/r/IK9-Privacy-Matters-IK9-Privacy-Plus-Fraud-Scam/internet/AP9-Privacy-Matters-IK9-Privacy-Plus-Unauthorized-fraudelent-charges-to-my-Credit-Card-421394. The posting time indicated is Arizona local time. Arizona does not observe daylight savings so the post time may be Mountain or Pacific depending on the time of year.
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- Report: #968219
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Complaint Review: tarsonisc /life style deals.com
tarsonisc /life style deals.comInternet United States of America
tarsonisc /life style deals.com i really am not quite sure which ripped me off when checking my bank account for another reason i noticed a charge for $39.95 from tarsoniscs. i called the number in my statement and a rep for tarsoniscs said it was lifestylesdeals.com who charged Internet
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This report was posted on Ripoff Report on 11/12/2012 03:55 PM and is a permanent record located here: http://www.ripoffreport.com/r/tarsonisc-life-style-dealscom/internet/tarsonisc-life-style-dealscom-i-really-am-not-quite-sure-which-ripped-me-off-when-checki-968219. The posting time indicated is Arizona local time. Arizona does not observe daylight savings so the post time may be Mountain or Pacific depending on the time of year.
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What's Driving Sustainable Energy Consumption? A Survey of the Empirical Literature
The focus of the paper is on the individual decision of energy consumers, and it's relation to sustainable consumption. Consumer behavior is based on individual decisions, but it depends largely on supply-side measures and an appropriate infrastructure (e.g. the availability of energy-efficient household equipment) and on socio-political factors (e.g. if systems of emissions trading or eco-labels exist). We derive some hypotheses on the determinants of sustainable energy consumption in residential buildings from a review of the empirical literature on the diffusion of energy efficient activities. While there is agreement on a lot of factors, the role of environmental attitudes and environmental behavior remains uncertain. Thus research needs are derived respectively. Finally, we specify these hypotheses for three specific technologies of sustainable energy consumption: Domestic appliances, micro-power and green electricity.
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Great product
I use this product every day. Purchased 3 over the last few years and all are still going strong. They make moving around from the desk to the warehouse a lot easier, rather than having to put my customer on hold and running back and forth.
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Index of content:
Volume 40, Issue 6, June 1972
Resource Letter ERPEE-1 on Energy: Resources, Production, and Environmental Effects40(1972); http://dx.doi.org/10.1119/1.1986677View Description Hide Description
Prepared at the request of the AAPT Committee on Resource Letters. This is one of a series of Resource Letters on different topics, intended to guide college physicists to some of the literature and other teaching aids that may help them improve course contents in specified fields of physics. No Resource Letter is meant to be exhaustive and complete; in time there may be more than one letter on some of the main subjects of interest. Comments and suggestions concerning the content and arrangement of letters as well as suggestions for future topics will be welcomed. Please send such communications to Professor Arthur Quinton, Chairman, Resource Letter Committee, Department of Physics, University of Massachusetts, Amherst, Massachusetts 01002.
Spreading Wave Packets—A Cautionary Note40(1972); http://dx.doi.org/10.1119/1.1986678View Description Hide Description
The spreading of a quantum mechanical wave packet is studied from two apparently equivalent points of view. For certain classes of wave functions, one prescription predicts spreading while the other does not. Reasons for this anomaly are discussed.
Spin Waves and Generalized Susceptibilities for Classical Models40(1972); http://dx.doi.org/10.1119/1.1986679View Description Hide Description
Lowest order noninteracting spin-wave theory for uniaxial, classical, Heisenberg, antiferromagnets, and ferrimagnets is considered. By use of the transverse generalized wave vector dependent magnetic susceptibility, the magnetization and mean energy are evaluated for low temperatures in the spin-wave approximation. Both two- and three-dimensional lattices are considered.
Standing Waves by Oblique Incidence on a Mirror40(1972); http://dx.doi.org/10.1119/1.1986680View Description Hide Description
We have employed the convenient wavelengths of microwaves to develop an introductory experiment with standing waves produced by oblique incidence upon a mirror. This experiment in physical optics was performed in two parts: (1) with polarization of the electric field perpendicular to the plane of incidence as an empirical introduction to the lower limit of the distance between maxima or minima in an interference pattern and (2) with polarization of the electric field parallel to the plane of incidence as an introduction to elliptical polarization. We have indicated the sources of error, illustrated graphically the sizes of errors to be expected, and suggested optimum dimensions of equipment.
On the Quantum Theory of the Symmetric Top40(1972); http://dx.doi.org/10.1119/1.1986681View Description Hide Description
The rotation operator of an ad hoc introduced particle is used to study the free symmetric top. A comprehensive and remarkable simple treatment is obtained.
Stimulated Emission and Bose-Einstein Statistics40(1972); http://dx.doi.org/10.1119/1.1986682View Description Hide Description
Einstein's derivation of Planck's blackbody formula using the A and B coefficients for spontaneous and stimulated transition probabilities is reviewed. Application of the Einstein-Fowler equation for statistical fluctuations, , shows that two terms contribute to the fluctuations, one from the particle nature of the system and one from its wave nature. When expressed in terms of the average number of quanta , occupying phase cells, the fluctuations become . This is exactly the first order variance of a system of particles distributed among phase cells in Bose-Einstein statistics. If stimulated emission is omitted in the Einstein derivation, the Wien formula results, and the fluctuations become equal to the single term , which is characteristic of classical statistics. Since the Planck law, which depends on both stimulated emission and stimulated absorption, gives fluctuation in accord with the Bose-Einstein statistics, whereas Wien's law, which depends on stimulated absorption alone, gives fluctuations in accord with classical statistics, it is concluded that the stimulated emission process is the mechanism responsible for the appearance of the Bose-Einstein statistics in blackbody radiation.
Quantum Theory of a Damped Two-Level Atom40(1972); http://dx.doi.org/10.1119/1.1986683View Description Hide Description
The interaction of a two-level atom with the radiation field in a cavity is discussed in quantum mechanical terms that are closely analogous to those used in discussing the classical Langevin equation; the quantum Langevin equation for this case, however, is nonlinear. A technique is developed for finding the measurable properties of the solution of the equations exactly; the properties of the solution are compared with those for the harmonic oscillator.
Poincaré's Rendiconti Paper On Relativity. Part II40(1972); http://dx.doi.org/10.1119/1.1986684View Description Hide Description
This is a continuation of the modernized presentation of Poincaré's Rendiconti paper (begun in the November 1971 issue of this Journal). It covers Secs. 5–8 of that paper, dealing with its central theme, as indicated by its title, "On the dynamics of the electron," the subject being of interest to both the historian of the classical theory of the electron and the historian of relativity.
Green's Function Treatment of Short Linear Heisenberg Chains40(1972); http://dx.doi.org/10.1119/1.1986685View Description Hide Description
The Callen and Tyablikov decoupling schemes used in the Green's function method are tested numerically for short Heisenberg linear chains which are first subjected to a constraint. The constraint is imposed to insure that internal excitations alone contribute to the calculated thermal averages so that in this sense these averages correspond to thermodynamic quantities. It is found that improved agreement with the exact results occurs if the Tyablikov decoupling is corrected by a term linear in the temperature.
Calculation of Magnetothermodynamic Properties of Paramagnetic Ions in Axial Crystal Fields40(1972); http://dx.doi.org/10.1119/1.1986686View Description Hide Description
The relations between the roots and coefficients of the characteristic equation for the spin Hamiltonian have been used to derive the magnetothermodynamic properties of paramagnetic ions in axial crystal fields. The physical basis of the derivation is discussed and some illustrative examples are included.
Research Project for Undergraduates: Ionic Thermoconductivity in Dielectrics40(1972); http://dx.doi.org/10.1119/1.1986687View Description Hide Description
Research projects for undergraduates should satisfy several conditions with regards to the physical insight, experimental manipulation, data analyses, and time for the experimental run that are required of the students. These conditions are satisfied by the study of dipole relaxations in dielectric materials using the method of ionic thermocurrents (ITC). ITC can be used to determine the concentration, activation energy, and relaxation time of dipoles in a dielectric. The necessary equipment and some possible research projects are discussed.
Even and Odd Spectra of One-Dimensional Symmetrical Potential. I. Schrödinger Theory40(1972); http://dx.doi.org/10.1119/1.1986688View Description Hide Description
The discrete spectrum of a one-dimensional symmetrical potential is studied within the framework of the Schrödinger theory using the variable phase approach. Separate Riccati equations characterizing the even and odd spectra are given, and the two lower states are defined by transcendental inequalities. Possible extension to a nonsymmetrical potential is also indicated and some numerical results are checked for a solvable potential of infinite range.
Even and Odd Spectra of One-Dimensional Symmetrical Potential. II. Dirac Theory40(1972); http://dx.doi.org/10.1119/1.1986689View Description Hide Description
The discrete spectrum of a one-dimensional symmetrical potential is studied within the framework of the Diractheory and compared to the Schrödinger spectrum, using the variable phase approach. Separate Riccati equations characterizing the even and odd spectra are given, and transcendental inequalities yield energy bounds on the two lower states. Conditions sufficient to support one odd state are established, and some numerical results are checked for a square well potential.
A Simple Demonstration of Flux Quantization in Superconductors40(1972); http://dx.doi.org/10.1119/1.1986690View Description Hide Description
An indiumfilm containing holes is used, together with a standard magnetometer, to demonstrate the quantization of flux in superconductors.
Uncertainty Relations for Nonsimultaneous Measurements40(1972); http://dx.doi.org/10.1119/1.1986691View Description Hide Description
The usual Heisenberg uncertainty relations are generalized to the case of nonsimultaneous measurements of position and momentum. The product of the corresponding uncertainties is bounded from below by a quantity depending on the dynamics of the system (the potential), and which may be lower than and even vanish. The case of two successive measurements of momentum and position is also treated, and one recovers the standard phenomenon of spreading of the wave packet. Whereas the case of an arbitrary potential can only be treated to lowest orders in the lime delay, a complete solution is given for the harmonic oscillator.
Illustrating Key Problems that Can Lead Towards a Quantitative Physical Biology40(1972); http://dx.doi.org/10.1119/1.1986692View Description Hide Description
Waddington has questioned whether a theoretical biology can be formulated, analogous to theoretical physics. This paper proposes two problems that physicists might tackle. One is to account for the relation between weight specific blood flow and weight specific oxygen consumption that is found with changing activity level in mammals. An essentially unique correlation is shown to exist for all sizes of mammals over their full range of aerobic activity. The correlation applies to the entire macroorganism as well as to the local microvascular bed (e.g., in muscle). It is thus representative of design of the metabolic apparatus at an integrative cellular level. The second problem is to account for the laws of population change in complex biological species (e.g., the human). Physics reached classical maturity by relating the macroscopic properties of matter to underlying atomistic properties. The two problems posed, cast at two different systems' levels (one the organism and the other society), call for a "classical" correlation with their underlying atomistic sources (the governing processes in the microvasculature and in the individual's decision making).
An Experiment to Determine the Relative Permeability of Ferrites40(1972); http://dx.doi.org/10.1119/1.1986693View Description Hide Description
Relative permeability of a ferrite rod can be determined by finding the series resonant frequencies of a simple L-C-R circuit with and without the rod inside the inductancecoil. Compared to other methods employed for the determination, of permeability, this method is simple and easy to perform in the laboratory. Using the value of from this experiment, —the absolute permeability of free space has been determined which provides a check for the correctness of this experiment.
Measurement of the Speed of Light40(1972); http://dx.doi.org/10.1119/1.1986694View Description Hide Description
Measurement of the speed of light by the rotating mirror method of Foucault using a laser source and photodiodedetector is described. With a path length of 38 m and rotation rates up to 500 Hz, the result is obtained.
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Solutions of Legendre's Equation—Simple Proof40(1972); http://dx.doi.org/10.1119/1.1986695View Description Hide Description
Bouncing Light Beam40(1972); http://dx.doi.org/10.1119/1.1986696View Description Hide Description


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Much More Than a Desktop Mill: The DIY VMC Build
A VMC (vertical machining center) is essentially a CNC vertical milling machine on steroids. Many CNC mills are just manual milling machines that have been converted to CNC control. They work nicely, but have a number of drawbacks when it comes to real world CNC milling: manual tool changes, lack of chip collection, lack of coolant containment, and backlash issues (which a manual machinist normally compensates for).
These problems are solved with a VMC, which will usually have an automatic tool changer, and an enclosure to contain coolant and wash chips down into a collection pan. They are, however, very …read more
Police Baffled? Send For The Radio Amateurs!
The police force in Evanston, Illinois had a problem on their hands. A mystery transmitter was blocking legal use of radio devices, car key fobs, cellphones, and other transmitters in an area of their city, and since it was also blocking 911 calls they decided to investigate it. Their first call for help went to the FCC who weren't much use, telling them to talk to the manufacturers of the devices affected.
Eventually they approached the ARRL, the USA's national amateur radio organisation, who sent along [Kermit Carlson, W9XA] to investigate. He fairly quickly identified the frequencies with the strongest …read more
A Refrigerator Cooled by Rubber Bands
Ever noticed that a rubber band gets warmer when it's stretched? The bands also get cooler when allowed to snap back to relaxed length? [Ben Krasnow] noticed, and he built a rubber band cooled refrigerator to demonstrate the concept. The idea of stretching a rubber band to make it hotter, then releasing it to make it cooler seems a bit counter intuitive. Normally when things get smaller (like a gas being compressed) they get hotter. When pressure is released the gas gets cooler. Rubber bands do the exact opposite. Stretching a rubber band makes it hot. Releasing the stretched band …read more
Arduino Versus Logic: The Coil Gun War Continues
Looks like another shot has been fired in the simmering Coil Gun Control War. This time, [Great Scott] is taken to the discrete woodshed with a simplified and improved control circuit using a single CMOS chip and a few transistors. Where will it end? Won't somebody think of the children?
The latest salvo is in response to [GreatScott]'s attempt to control a DIY coil gun with discrete logic, which in turn was a response to comments that he took the easy way out and used an Arduino in the original build. [Great Scott]'s second build was intended to justify the …read more
Fine Business, Good Buddy: Amateur Radio for Truckers
Summer is the season for family road trips here in the US, and my family took to the open road in a big way this year. We pulled off a cross-country relocation, from Connecticut to Idaho. Five days on the road means a lot of pit stops, and we got to see a lot of truck stops and consequently, a lot of long-haul truckers. I got to thinking about their unique lifestyle and tried to imagine myself doing that job. I wondered what I'd do hour after long hour, alone in the cab of my truck. I figured that I'd …read more


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Ryan Walter News Archive
News -- April 2016 (1)
- 4/15 A Winning Habit: Habs Should Not Trade P.K. Subban.: The Habs PK Subban was a topic of discussion during a TSN-690 radio segment with Tony Marinaro boldly claiming their is a 50/50...
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- Report: #306605
Report - Rebuttal - Arbitrate
Complaint Review: Passive Profits
Passive ProfitsSalt Lake City, Utah U.S.A.
Passive Profits SCAM SCAM SCAM SCAM SCAM SCAM SCAM!! Salt Lake City Utah
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Las Vegas, Nevada
This report was posted on Ripoff Report on 02/06/2008 08:12 AM and is a permanent record located here: http://www.ripoffreport.com/r/Passive-Profits/Salt-Lake-City-Utah/Passive-Profits-SCAM-SCAM-SCAM-SCAM-SCAM-SCAM-SCAM-Salt-Lake-City-Utah-306605. The posting time indicated is Arizona local time. Arizona does not observe daylight savings so the post time may be Mountain or Pacific depending on the time of year.
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Mohamad Ali was named President and CEO in December 2014 to help Carbonite continue to grow and serve the ever-evolving technology needs of the small and mid-sized businesses that power the world. Prior to Carbonite, Ali served as Chief Strategy Officer at Hewlett-Packard Co., reporting to the Chairman and CEO. Before HP, Ali was CEO of the Workforce Optimization division of Aspect Software, and before that he led Avaya's $2 billion Global Services division as its president. Ali also held various executive positions at IBM.
Ali is a long-time resident of Boston, Carbonite's world headquarters, where he lives with his wife and children. He attended Stanford and received a Bachelor of Science in Computer Engineering, a Bachelor of Arts in History, and a Master's degree in Electrical Engineering. He serves on the boards of City National Bank, Oxfam America, and the Massachusetts Technology Leadership Council.
Scott Daniels joined the Carbonite board of directors in 2016, adding valuable experience in growth investment and public markets to the Carbonite board.
Daniels has spent his entire career investing in and working with public technology companies. He was a senior analyst at Shannon River Partners, a private hedge fund focused on technology, media and communications companies. Prior to Shannon River, Daniels was a partner at S Squared Technology, a technology investment fund where he evaluated and invested in multiple publicly traded small and midsized emerging growth technology companies around the world. At S Squared, Daniels focused on enterprise software, storage, networking and SaaS sectors.
Before joining S Squared, he was a research analyst at CIBC World Markets covering software. Early in his career, Daniels spent five years working in the software industry in finance operations roles. Daniels received his B.A. degree from University of Pennsylvania, and holds an M.B.A. from Columbia Business School.
Jeff Flowers (co-founder and former CTO and Chief Architect at Carbonite) is a seasoned technology executive with deep IT and technical expertise. Jeff has worked with David Friend (CEO) since 1982 and co-founded Sonexis, FaxNet and Pilot Software. At Sonexis and FaxNet, he also served as CTO. In 2009, he was named CTO of the Year by the Mass Technology Leadership Council.
In addition to the three companies he co-founded with David, Jeff served as VP of Engineering for Computer Pictures. He also served as VP of Development at ON Technology Corporation, a software vendor that provided groupware and utility products for Apple and Novell Netware operating environments. During Jeff's tenure, ON Technology completed its IPO.
Jeff holds a B.S. and M.S. in Information and Computer Science from the Georgia Institute of Technology and attended the Northeastern University School of Business.
David Friend has been a successful technology entrepreneur for over 25 years. After serving as President of ARP Instruments, he co-founded four companies: Sonexis, FaxNet, Pilot Software, and Computer Pictures Corporation. In 2010, David was named Ernst & Young Entrepreneur of the Year in the Emerging Technology category for the New England Region. He has been featured in USA Today, Tech Capital, The Boston Globe, Mass HiTech, Fortune, Forbes and Tom Peter's best-selling management book, The Pursuit of Wow!
David has been a lecturer at MIT's Sloan School of Management and is an active supporter of music and the arts in Boston. He is a trustee (emeritus) of the New England Conservatory, Berklee College of Music, and the Brookings Institution in Washington, D.C.
David holds a bachelor's degree in engineering from Yale University and attended the Princeton University Graduate School of Engineering where he was a David Sarnoff Fellow. He is an avid marathoner, distance cyclist, windsurfer, and hiker.
Peter Gyenes joined the Carbonite board of directors in 2015, bringing experience with corporate growth and value creation to our vision for business continuity for SMBs.
Peter was most recently the Chairman and Chief Executive Officer of Ascential Software Corporation, until its acquisition by IBM in April 2005. He brings to Carbonite four decades of experience in technical, sales, marketing and general management positions within the computer systems and software industry in the Americas, Europe and Asia/Pacific.
He serves on the boards of Sophos, Inc., Intralinks, Inc., Lawson Software, Inc., Pegasystems Inc., RealPage Inc., VistaPrint N.V., a number of privately held technology companies and the Massachusetts Technology Leadership Council (Trustee Emeritus). Peter has a bachelor's degree in mathematics and an MBA from Columbia University in New York.
Charles Kane is a seasoned public company executive and director. Mr. Kane has served as president and CEO of Corechange, an enterprise software company; as CFO of Global BPO Services Corp., RSA Security, Aspen Technology, and Informix Software; and in other financial management roles with Stratus Computer, Prime Computer, and Deloitte & Touche LLP.
Since November of 2006, Mr. Kane has served as a Board member and audit committee chairman of Progress Software. He has served in the same capacity for Demandware since May 2010. Previously, Mr. Kane served as a member of the Board of Borland Software, Netezza, and Applix.
Mr. Kane holds a B.B.A. in Accounting from the University of Notre Dame, an M.B.A. in International Finance from Babson College, and is a senior lecturer of International Finance at the Massachusetts Institute of Technology's Sloan School of Management.
Todd Krasnow is an accomplished entrepreneur, consumer sales & marketing executive and early stage venture investor. Currently at Highland Capital Partners, Todd serves as a Director on the Boards of several privately-held companies including Quraz, OnForce, and C & S Wholesale Grocers, and is a member of the Board of Advisors at Harvard Business School's Arthur Rock Center for Entrepreneurship.
Previously, Todd was a member of the original management team at Staples and served as its EVP of Sales and Marketing. During his tenure at Staples, Todd won a gold "Clio" award for the best retail advertising in the United States while the company reached over $7 billion in sales.
He holds an M.B.A. from Harvard Business School and an A.B. in Chemistry from Cornell University.
Steve Munford is an accomplished leader in the security industry with vast experience in major strategic shifts.
Steve is currently the non-executive chairman of the Sophos Ltd. board of directors. He served as Sophos' CEO from 2006 to 2012 and, during that time, led the company through a period of dramatic growth, more than tripling bookings. Prior to his role as CEO, Steve served as President of Sophos for North America and then became Chief Operating Officer, responsible for the day-to-day running of the company and its senior management team. Previously, he was President of ActiveState before its acquisition by Sophos in 2003. Under his leadership, ActiveState established itself as a global leader in email security software.
Steve has a bachelor's degree in economics from the University of Western Ontario and has an MBA from Queen's University, Ontario.


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With Instructables you can share what you make with the world, and tap into an ever-growing community of creative experts.
This Is A Tutorial On How To Make A Super In-Inexpensive Pen From Bullet Casings...
Supplies Are quite simple all you need is: -Bullet casings(Find Them Any Where Guns Are Shot) -Cheap Pen -Duct Tape Or Super Glue -Any Tool That Cuts (best works with multi-tool, or ...
First Choose Your Casing Size For This Build I Chose A 7mm Remington mag casing. Then Pull The Main part of the pen of to get the arrow ...
Now Put them side by side mesure then cut stem too a little smaller than the casing so it doesnt keep touching the bottom but dont put it ...
So now take the elmers school glue or super glue and glue the piece of the stem You cut just so ink does not run out. Drying................................ Now Get The ...
Make your own Rifle Cartridge Pen blanksby switch62
Air gun Bulletsby ~FROGYOU~
Cardboard/duct tape sniper rifleby TheArtOfWeapons
Pellet or bullet trapby Snidely70448
Nerf longshot clip mod: Drum magazineby Ratchet_M60
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