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Sample records for expanded polytetrafluoroethylene gore-tex

  1. Frontal suspension for congenital ptosis using an expanded polytetrafluoroethylene (Gore-Tex® sheet: one-year follow-up

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    Nakauchi K

    2013-01-01

    Full Text Available Kazuaki Nakauchi,1 Hidenori Mito,2 Osamu Mimura11Hospital of Hyogo College of Medicine, Hyogo, 2Ide Eye Hospital, Yamagata, JapanBackground: The frontalis suspension technique is the surgical method of choice in patients with ptosis and a levator function of 4 mm or less. Several types of materials have been used, including Gore-Tex®, which has been used successfully as a frontalis sling material since 1986. Recently, a Gore-Tex sheet (wider than a sling or strip suspension was reported. This paper reports the results of 27 eyes from 20 patients with congenital ptosis treated using the frontalis suspension technique with the newly developed Gore-Tex Most Versatile Patch (MVP sheet.Methods: All patients underwent surgery between April 2007 and September 2011 and were followed up for at least one year. The average follow-up duration was 18 months, with a range of 12–36 months. The average patient age was 45 (5–85 years, and the group included 11 males and nine females. Thirteen cases demonstrated ptosis in one eye, and seven cases involved both eyes. The patients were divided by age into a younger group and an older group. All ptosis procedures were performed using the Gore-Tex MVP sheet. The implant was normally 7 mm wide for adults and 5 mm wide for children. The implantation method was the same as that used for the sheet shape fascia.Results: In all patients, satisfactory functional results were observed at the 6-month follow-up examination. Eyelid opening heights were also obtained. The average marginal reflex distance (MRD was -0.5 mm preoperatively, which improved to +1.9 mm after surgery. After one year, average MRD was +1.6 mm. MRD attenuation was more frequent in the younger group. There were no cases requiring redo surgery and only one case of exposure.Keywords: polytetrafluoroethylene, Gore-Tex®, frontalis suspension, congenital ptosis, recurrence

  2. Histopathological changes in the human larynx following expanded polytetrafluroethylene (Gore-Tex® implantation

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    Sheffield E

    2005-01-01

    Full Text Available Abstract Background Expanded polytetrafluroethelyne (e PTFE, Gore-Tex® has been advocated as an implant material for medialization of the vocal fold. Animal studies involving rabbits and a porcine model have demonstrated host tolerance of the implant. There have been no reports describing the histological changes in a human laryngectomy specimen with a Gore-Tex implant. Case presentation The histological findings in a laryngectomy specimen of a patient previously implanted with e PTFE for medialization of a paralyzed vocal fold following excision of a vagal neurofibroma were studied. Histopathology revealed a mild foreign-body giant cell granulomatous reaction with some associated fibrosis. The granulomatous response was limited to the periphery of the Gore-Tex and although it closely followed the profile of the material it did not encroach into or significantly break up the material. There was no significant neutrophilic or lymphocytic inflammation. Conclusions Our findings are consistent with the animal models confirming that Gore-Tex implantation does not result in a significant granulomatous reaction in the human larynx over a 13-month period. Moreover, there is no evidence of resorption or infection. Further, the lack of lymphocytes in association with the granulomas indicates that there is no significant immunological hypersensitivity. Histologically, the slight permeation by connective tissue is similar to that seen in Gore-Tex vascular and cardiac implants. The degree of the slight giant cell response appears to be dependent on the profile of the material; a sharp edge incited more of a response than a flat surface.

  3. Aplicaciones del Gore-tex en Oftalmología

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    María Cáceres Toledo

    Full Text Available Objetivo: evaluar los resultados terapéuticos en la corrección quirúrgica de afecciones oculares, con el uso del Gore-tex y con la modificación realizada a la técnica quirúrgica convencional de la suspensión al frontal. Métodos: se realizó un estudio descriptivo prospectivo en una serie de 16 casos: 7 con ptosis, 5 con estrabismo y 4 con retracción palpebral inferior. Para la corrección de la retracción y la ptosis se utilizaron fragmentos del referido material y una sutura de Gore-tex en la corrección del estrabismo y en algunos casos con ptosis. Se colocaron 2 mm de Gore-tex por cada milímetro de retracción y de ptosis palpebral. Se corrigieron 2 dioptrías prismáticas por cada milímetro de retroinserción del músculo afectado. Resultados: fueron satisfactorios en un total de 13 casos (87 %. La mayoría de los pacientes operados con la modificación realizada a la técnica de la suspensión al frontal disminuyeron los mm de caída hasta el nivel fisiológico palpebral. Conclusiones: los resultados son satisfactorios en la mayoría de los casos operados con el uso del Gore-tex y con la técnica de suspensión al frontal modificada.

  4. An in vivo comparative study of the e-polytetrafluoroethylene vascular prostheses: Vitaflon and Gore-Tex.

    Science.gov (United States)

    Dobrova, N B; Gorodkov, A J; Sidorenko, E S; Schekhter, A B; Baquey, C

    1999-12-01

    A comparative study was performed in order to validate new Russian e-PTFE vascular prostheses Vitaflon (St. Petersburg, Russia). The Gore-Tex prostheses were chosen as a referential model. The prostheses were implanted in the venous and arterial positions in 13 dog experiments. After the implantation time was over a comprehensive histological and histochemical examination of excized specimens was performed. It was demonstrated that there is no difference in healing and functional properties between the two studied prostheses. Copyright 1999 Kluwer Academic Publishers

  5. The Gore-Tex prosthetic ligament as a salvage procedure in deficient knees

    NARCIS (Netherlands)

    Roolker, W.; Patt, T. W.; van Dijk, C. N.; Vegter, M.; Marti, R. K.

    2000-01-01

    The purpose of this study was to evaluate the results of prosthetic ligament replacement of the anterior cruciate ligament (ACL) or posterior cruciate ligament (PCL) with the Gore-Tex polytetrafluorethyene prosthesis (W.L. Gore and Co., Flagstaff, Ariz. ) in 52 patients (54 knees). All patients

  6. Repair of bile duct injuries with Gore-Tex vascular grafts: experimental study in dogs.

    Science.gov (United States)

    Gómez, Néstor A; Alvarez, Ludwig R; Mite, Alfredo; Andrade, Jean P; Alvarez, José R; Vargas, Paola E; Tomalá, Nancy E; Vivas, Alex F; Zapatier, Jorge A

    2002-01-01

    Bile duct injury is the most feared complication related to biliary tract operations. The goal of this investigation was to offer an alternative treatment that might prevent this complication. Twelve mongrel dogs, thin-walled FEP-ringed Gore-Tex vascular grafts, and Gore-Tex sutures were used in this study. The dogs were randomized into three groups of four according to the length of time of graft implantation: group 1 = 1 month; group 2 = 2 months; and group 3 = 3 months. During the first part of the study, a biliary injury was induced by ligating the middle choledocus after performing a conventional cholecystectomy. During the second part of the study, biliodigestive and biliobiliary anastomosis were performed using Gore-Tex vascular grafts prior to resection of the stenotic area. Initially, an increase in serum bilirubin and alkaline phosphatase levels was noted. Two weeks later, after implantation of the grafts, these values returned to normal. Thin-walled FEP-ringed Gore-Tex vascular grafts were found to be useful in the repair of bile duct injuries, especially in complete transections of the common bile duct. The ductility and flexibility of the material allows any type of anastomosis to be performed, especially when bile duct-gut anastomosis is technically difficult.

  7. Tracheal reconstruction by re-inforced Gore-Tex in esophageal submuscular tunneling: An experimental study

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    Hodjati Hossein

    2011-01-01

    Full Text Available Background: Tracheal reconstructions are aimed at rearranging or replacing parts of the tracheal tissue by different techniques. Here we introduce a new technique for tracheal reconstruction. Methods: In 10 adult dogs, after intubation with an endotracheal tube, a segment of trachea including seven tracheal rings was resected circumferentially. A submuscular tunnel was induced between mucosal and muscular layers of the adjacent esophagus lying right next to the trachea. The esophageal submuscular tunnel starts and ends exactly at the level of distal and proximal ends of tracheal resection, respectively. Inforced Gore-Tex passed through the esophageal submuscular tunnel the distal segment of trachea and end-to-end anastomosis were made between distal ends of Gore-Tex and trachea, then endotracheal tube removed and the same procedure was made for proximal ends of Gore-Tex and trachea. Afterward, the proximal and distal ends of the esophageal tunnel were approximated to proximal and distal tracheal parts over the anastomosis. Results: All dogs, except one due to anesthetic problem, survived and tolerated the operation; the first two dogs experienced postoperative fever, aspiration pneumonia, and died due to tracheoesophageal fistula. All survived animals were eating and barking well. We started to scarify dogs at least 6 and 12 weeks after operation for microscopy and pathologic examination. The Gore-Texes were patent and supported externally with fibrous connective tissue in esophageal tunneling, with in growth of respiratory epithelium on inner surfaces. Conclusion: Air tightness, good re-epithelialization, and relatively no limitation of esophageal length and no risk of luminal collapse are advantages of tracheal reconstruction by submuscular esophageal tunneling. This new method is worthy of further investigation, as it is technically feasible and easy to implement.

  8. Anti-inflammatory and Antibacterial Effects of Covalently Attached Biomembrane-Mimic Polymer Grafts on Gore-Tex Implants.

    Science.gov (United States)

    Jin, Young Ju; Kang, Sunah; Park, Pona; Choi, Dongkil; Kim, Dae Woo; Jung, Dongwook; Koh, Jaemoon; Jeon, Joohee; Lee, Myoungjin; Ham, Jiyeon; Seo, Ji-Hun; Jin, Hong-Ryul; Lee, Yan

    2017-06-07

    Expanded polytetrafluoroethylene (ePTFE), also known as Gore-Tex, is widely used as an implantable biomaterial in biomedical applications because of its favorable mechanical properties and biochemical inertness. However, infection and inflammation are two major complications with ePTFE implantations, because pathogenic bacteria can inhabit the microsized pores, without clearance by host immune cells, and the limited biocompatibility can induce foreign body reactions. To minimize these complications, we covalently grafted a biomembrane-mimic polymer, poly(2-methacryloyloxylethyl phosphorylcholine) (PMPC), by partial defluorination followed by UV-induced polymerization with cross-linkers on the ePTFE surface. PMPC grafting greatly reduced serum protein adsorption as well as fibroblast adhesion on the ePTFE surface. Moreover, the PMPC-grafted ePTFE surface exhibited a dramatic inhibition of the adhesion and growth of Staphylococcus aureus, a typical pathogenic bacterium in ePTFE implants, in the porous network. On the basis of an analysis of immune cells and inflammation-related factors, i.e., transforming growth factor-β (TGF-β) and myeloperoxidase (MPO), we confirmed that inflammation was efficiently alleviated in tissues around PMPC-grafted ePTFE plates implanted in the backs of rats. Covalent PMPC may be an effective strategy for promoting anti-inflammatory and antibacterial functions in ePTFE implants and to reduce side effects in biomedical applications of ePTFE.

  9. Characterization of a tubular flow chamber for studying platelet interaction with biologic and prosthetic materials: deposition of indium 111-labeled platelets on collagen, subendothelium, and expanded polytetrafluoroethylene

    International Nuclear Information System (INIS)

    Badimon, L.; Turitto, V.; Rosemark, J.A.; Badimon, J.J.; Fuster, V.

    1987-01-01

    A plastic (Plexiglas) chamber for evaluating platelet deposition under controlled hemodynamic conditions has been developed. The perfusion chamber has been designed to retain the cylindrical shape typical of the vasculature, to be flexible enough to accept a variety of biologic and prosthetic materials, and to simulate a broad range of physiologic flow conditions in either an ex vivo or in vitro perfusion system. Three type of surfaces were exposed to blood flowing directly from the carotid artery of a heparinized pig through the perfusion chamber: de-endothelialized pig aorta, collagen strips from rabbit Achilles tendon, and an expanded polytetrafluoroethylene material (Gore-Tex). Platelets, previously radiolabeled with indium 111 and injected into the animal, were quantified on the material surface, and the total number of deposited platelets determined for a range of blood flow rates (5 to 40 ml/min) and exposure times (0.5 to 20 minutes). The deposition rates were correlated with theory for describing the mass transport of platelets to the test surface. At the wall shear rates investigated (105 to 850 sec-1), the deposition of platelets on subendothelium was strongly dependent on the local flow conditions. Values of deposition on Gore-Tex obtained at similar flow conditions (105 to 425 sec-1) were reduced compared with that observed on subendothelium and showed a markedly weaker dependence on the shear rate. In contrast, deposition of platelets on collagen was more than an order of magnitude greater than on subendothelium and showed a dependence on flow only at the lowest flow rate studied (10 ml/min). The results indicate that collagen is much more reactive than subendothelium and Gore-Tex with respect to the growth and stability of platelet aggregates and moreover suggest that flow mechanisms for depositing platelets on various surface may be substantially different

  10. Characterization of a tubular flow chamber for studying platelet interaction with biologic and prosthetic materials: deposition of indium 111-labeled platelets on collagen, subendothelium, and expanded polytetrafluoroethylene

    Energy Technology Data Exchange (ETDEWEB)

    Badimon, L.; Turitto, V.; Rosemark, J.A.; Badimon, J.J.; Fuster, V.

    1987-12-01

    A plastic (Plexiglas) chamber for evaluating platelet deposition under controlled hemodynamic conditions has been developed. The perfusion chamber has been designed to retain the cylindrical shape typical of the vasculature, to be flexible enough to accept a variety of biologic and prosthetic materials, and to simulate a broad range of physiologic flow conditions in either an ex vivo or in vitro perfusion system. Three type of surfaces were exposed to blood flowing directly from the carotid artery of a heparinized pig through the perfusion chamber: de-endothelialized pig aorta, collagen strips from rabbit Achilles tendon, and an expanded polytetrafluoroethylene material (Gore-Tex). Platelets, previously radiolabeled with indium 111 and injected into the animal, were quantified on the material surface, and the total number of deposited platelets determined for a range of blood flow rates (5 to 40 ml/min) and exposure times (0.5 to 20 minutes). The deposition rates were correlated with theory for describing the mass transport of platelets to the test surface. At the wall shear rates investigated (105 to 850 sec-1), the deposition of platelets on subendothelium was strongly dependent on the local flow conditions. Values of deposition on Gore-Tex obtained at similar flow conditions (105 to 425 sec-1) were reduced compared with that observed on subendothelium and showed a markedly weaker dependence on the shear rate. In contrast, deposition of platelets on collagen was more than an order of magnitude greater than on subendothelium and showed a dependence on flow only at the lowest flow rate studied (10 ml/min). The results indicate that collagen is much more reactive than subendothelium and Gore-Tex with respect to the growth and stability of platelet aggregates and moreover suggest that flow mechanisms for depositing platelets on various surface may be substantially different.

  11. Pericardial tissue valves and Gore-Tex conduits as an alternative for right ventricular outflow tract replacement in children.

    Science.gov (United States)

    Allen, Bradley S; El-Zein, Chawki; Cuneo, Betina; Cava, Joseph P; Barth, Mary Jane; Ilbawi, Michel N

    2002-09-01

    There is still no perfect conduit for reconstruction of the right ventricular outflow tract (RVOT) in children. Homografts are not always available in the appropriate size, and degenerate in a few years. This study evaluates the pericardial valve with Gore-Tex conduit as an alternative for RVOT construction. From January 1, 1993, to September 30, 1999, a pericardial tissue valve was inserted in all patients undergoing RVOT reconstruction or pulmonary valve replacement (PVR) who were large enough to accommodate a tissue valve. In patients without a native main pulmonary artery, a new technique was used to construct an RV-PA conduit out of a flat sheet of Gore-Tex, as Dacron frequently leads to stenosis. Data were collected by retrospective review, follow-up echocardiograms, and assessment by a single cardiologist. There were 48 patients, 22 undergoing a PVR alone and 26 a RV-PA valved Gore-Tex conduit. Diagnosis included tetralogy of Fallot (n = 25); truncus arteriosis (n = 9); ventricular septal defect with PA (n = 5); DORV (n = 4); D-TGA with PS (n = 2); and 1 each IAA with sub AS, VSD with PI, and PS s/p Ross procedure. Patient age ranged from 3 to 33 years and 98% were reoperations. The valve sizes ranged from 19 to 33 mm and the median hospital length of stay was 4 days. There were 2 (4.2%) perioperative and 1 (2.1%) late deaths, none related to the valve or Gore-Tex conduit. At a follow-up of 15 to 86 months (mean 43 +/- 16 months), all remaining 45 patients are New York Heart Association class I, all valves are functional, and no patient has required valve or conduit replacement or revision; more importantly, echocardiogram revealed no significant valve or conduit stenosis (mean gradient 16 +/- 8 mm Hg) and no evidence of regurgitation or structural degeneration. A pericardial tissue valve and Gore-Tex conduit provides a reliable alternative for RVOT reconstruction in pediatric patients. It is readily available, molds in the limited retrosternal space, and

  12. Gore-tex® versus resolut adapt® GTR membranes with perioglas® in periodontal regeneration

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    Amit Wadhawan

    2012-01-01

    Full Text Available Background: Successful reconstruction of periodontal tissues destroyed due to periodontitis has been an evasive goal for the periodontists. Several GTR materials and bone grafts have been tried with varied success rates. Aims and Objectives: The aim of the present study was to evaluate and compare the efficacy of non-resorbable (GoreTex® and bioabsorbable (Resolut Adapt® membranes in combination with bioactive glass (PerioGlas® in the treatment of periodontal intrabony defects. Materials and Methods: Ten chronic periodontitis patients having bilateral matched intrabony defects were treated with non-resorbable membrane (GoreTex® and bioactive glass or the bioresorbable membrane (Resolut Adapt® and bioactive glass in split mouth design. Clinical parameters like plaque index, gingival index, probing pocket depth, clinical attachment level, and gingival recession were recorded at baseline and 9 months post-operatively. Similarly, radiographic (linear CADIA and intra-surgical (re-entry measurements were evaluated at baseline and 9 months post-operatively. Results: Both the membrane groups showed clinically and statistically significant improvement in clinical parameters i.e., reduction in probing depth (4.6 ± 1.4 mm vs. 3.7 ± 1.3 mm and gain in clinical attachment level (4.6 + 1.6 vs. 3.2 ± 1.5 mm for non-resorbable and bioresorbable membrane groups, respectively. Similar trend was observed when radiographical and intra-surgical (re-entry measurements were evaluated and compared, pre- and post-operatively at 9 months. However, on comparison between the two groups, the difference was statistically not significant. Conclusion: Both the barrier membranes i.e., non-resorbable (Gore-Tex® and bioabsorbable (Resolut Adapt® membranes in combination with bioactive glass (PerioGlas® were equally effective in enhancing the periodontal regeneration.

  13. Sutures for inguinal herniorrhaphy--a comparison of monofilaments with PTFE.

    Science.gov (United States)

    Cahill, J.; Northeast, A. D.; Jarret, P. E.; Leach, R. D.

    1989-01-01

    Polybutester (Novafil, Davis & Geck) and expanded polytetrafluoroethylene PTFE (Gore-tex, W L Gore) were compared with nylon (Ethilon, Ethicon UK) for elective inguinal herniorrhaphy. PTFE had the best handling characteristics, but is expensive, and increased wound sepsis attended its use. Polybutester had significantly better handling characteristics, and is an attractive alternative to nylon for hernia repair. PMID:2705719

  14. Adoption of new technology in sports medicine: case studies of the Gore-Tex prosthetic ligament and of thermal capsulorrhaphy.

    Science.gov (United States)

    Virk, Sohrab S; Kocher, Mininder S

    2011-01-01

    Evaluation of new technology in sports medicine is supposed to promote improvements in the care of patients. It is also supposed to prohibit technology that can harm patients. This evaluation process is not perfect and at times can promote technology that not only does not help patients but may harm them. Two examples of new sports medicine technology that were widely adopted but eventually abandoned are thermal capsulorrhaphy for treatment of shoulder instability and the Gore-Tex prosthetic ligament (W. L. Gore & Associates, Flagstaff, AZ) for patients with anterior cruciate ligament deficiency. On analysis of the quick adoption of these 2 failed procedures, certain recommendations are apparent for improvement of the evaluation process. There must be a sound rationale behind any new technology, basic science research into the theory of the medical technology, and demonstrated improvements in animal models and clinical studies that are prospective cohort studies or randomized controlled trials, and finally, there must be careful follow-up and postmarket surveillance. Copyright © 2011 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

  15. Case Report: Rapid staged abdominal closure using Gore-Tex® mesh as a bridge to primary omphalocele sac closure

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    William C. Kethman

    2016-06-01

    Full Text Available Omphaloceles present an ongoing challenge due to significant variations in presentation and associated co-morbidities. Diverse management strategies have been described to tackle many of the fundamental challenges of closure and reconstruction of the abdominal wall – this fact demonstrates a need for increasingly individualized management options for this complex disease. We describe a novel method of rapid staged abdominal wall closure using Gore-Tex® mesh as a bridge to primary omphalocele closure in an infant with partial Pentalogy of Cantrell and giant ruptured omphalocele. This strategy can be used in management of some of the most complex abdominal wall defects.

  16. Self expandable polytetrafluoroethylene stent for carotid blowout syndrome.

    Science.gov (United States)

    Tatar, E C; Yildirim, U M; Dündar, Y; Ozdek, A; Işik, E; Korkmaz, H

    2012-01-01

    Carotid blowout syndrome (CBS) is an emergency complication in patients undergoing treatment for head and neck cancers. The classical management of CBS is the ligation of the common carotid artery, because suturing is not be possible due to infection and necrosis of the field. In this case report, we present a patient with CBS, in whom we applied a self-expandable polytetrafluoroethylene (PTFE) stent and observed no morbidity. Endovascular stent is a life-saving technique with minimum morbidity that preserves blood flow to the brain. We believe that this method is preferable to ligation of the artery in CBS.

  17. Clinical trial comparing autogenous fascia lata sling and Gore-Tex suspension in bilateral congenital ptosis

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    Elsamkary MA

    2016-03-01

    Full Text Available Mahmoud Ahmed Elsamkary,1 Maged Maher Salib Roshdy1,2 1Ophthalmology Department, Faculty of Medicine, Ain Shams University, Cairo, Egypt; 2Pediatric Ophthalmology Department, Al Watany Eye Hospital, Cairo, Egypt Purpose: To study the effect of autogenous fascia lata sling (AFLS versus Gore-Tex suspension (GTS regarding the functional and aesthetic outcomes in patients with bilateral congenital ptosis. Patients and methods: A prospective comparative randomized single-center study enrolled 110 patients with bilateral congenital ptosis. One group (n=55 underwent AFLS and the second group (n=55 underwent GTS. Exclusion criteria were good levator function, absent Bell’s phenomenon, and abnormal ocular motility. Follow-up period was 2 years. Functional outcome was measured from digital photos by analysis of upper eyelid margin position relative to the superior limbus and classified as very good (<3 mm, good (3–5 mm, poor (>5 mm, and recurrent. Aesthetic outcome was assessed in terms of lid contour, symmetry of eyelid height, and lid crease presence. Complications were also reported. Results: Failure rate (recurrence and complications was less in AFLS (P=0.035. Symmetrical lid height and good contour were more frequently attained by AFLS (P=0.007 and 0.047, respectively. However, the frequency of very good, good, poor, recurrence, lagopthalmos, ectropion, infection, and formed lid crease individually showed no statistically significant difference (P=0.252, 0.482, 1, 0.489, 0.438, 1, 0.618, and 0.506, respectively. Conclusion: AFLS is a better choice in surgery for patients with bilateral congenital ptosis because it has fewer complications and a lesser recurrence rate than GTS. Keywords: ptosis surgery, surgical outcomes, ptosis recurrence, lagophthalmos

  18. Vivosorb (R), Bio-Gide (R), and Gore-Tex (R) as barrier membranes in rat mandibular defects : an evaluation by microradiography and micro-CT

    NARCIS (Netherlands)

    Gielkens, Pepijn F. M.; Schortinghuis, Jurjen; de Jong, Johan R.; Raghoebar, Gerry M.; Stegenga, Boudewijn; Bos, Ruud R. M.

    Objectives: The objectives of this study were to determine whether a new degradable synthetic barrier membrane (Vivosorb (R)) composed of poly(DL-lactide-epsilon-caprolactone) (PDLLCL) can be useful in implant dentistry and to compare it with collagen and expanded polytetrafluoroethylene (ePTFE)

  19. A Modified Rabbit Ulna Defect Model for Evaluating Periosteal Substitutes in Bone Engineering: A Pilot Study

    Energy Technology Data Exchange (ETDEWEB)

    El Backly, Rania M. [DIMES, University of Genova, Genova (Italy); IRCCS AOU San Martino–IST Istituto Nazionale per la Ricerca sul Cancro, Genova (Italy); Faculty of Dentistry, Alexandria University, Alexandria (Egypt); Chiapale, Danilo [IRCCS AOU San Martino–IST Istituto Nazionale per la Ricerca sul Cancro, Genova (Italy); Muraglia, Anita [Biorigen S.R.L., Genova (Italy); Tromba, Giuliana [Sincrotrone Trieste S.C.P.A., Trieste (Italy); Ottonello, Chiara [Biorigen S.R.L., Genova (Italy); Santolini, Federico [IRCCS AOU San Martino–IST Istituto Nazionale per la Ricerca sul Cancro, Genova (Italy); Cancedda, Ranieri; Mastrogiacomo, Maddalena, E-mail: maddalena.mastrogiacomo@unige.it [DIMES, University of Genova, Genova (Italy); IRCCS AOU San Martino–IST Istituto Nazionale per la Ricerca sul Cancro, Genova (Italy)

    2015-01-06

    The present work defines a modified critical size rabbit ulna defect model for bone regeneration in which a non-resorbable barrier membrane was used to separate the radius from the ulna to create a valid model for evaluation of tissue-engineered periosteal substitutes. Eight rabbits divided into two groups were used. Critical defects (15 mm) were made in the ulna completely eliminating periosteum. For group I, defects were filled with a nanohydroxyapatite poly(ester urethane) scaffold soaked in PBS and left as such (group Ia) or wrapped with a tissue-engineered periosteal substitute (group Ib). For group II, an expanded-polytetrafluoroethylene (e-PTFE) (GORE-TEX{sup ®}) membrane was inserted around the radius then the defects received either scaffold alone (group IIa) or scaffold wrapped with periosteal substitute (group IIb). Animals were euthanized after 12–16 weeks, and bone regeneration was evaluated by radiography, computed microtomography (μCT), and histology. In the first group, we observed formation of radio-ulnar synostosis irrespective of the treatment. This was completely eliminated upon placement of the e-PTFE (GORE-TEX{sup ®}) membrane in the second group of animals. In conclusion, modification of the model using a non-resorbable e-PTFE membrane to isolate the ulna from the radius was a valuable addition allowing for objective evaluation of the tissue-engineered periosteal substitute.

  20. A Modified Rabbit Ulna Defect Model for Evaluating Periosteal Substitutes in Bone Engineering: A Pilot Study

    International Nuclear Information System (INIS)

    El Backly, Rania M.; Chiapale, Danilo; Muraglia, Anita; Tromba, Giuliana; Ottonello, Chiara; Santolini, Federico; Cancedda, Ranieri; Mastrogiacomo, Maddalena

    2015-01-01

    The present work defines a modified critical size rabbit ulna defect model for bone regeneration in which a non-resorbable barrier membrane was used to separate the radius from the ulna to create a valid model for evaluation of tissue-engineered periosteal substitutes. Eight rabbits divided into two groups were used. Critical defects (15 mm) were made in the ulna completely eliminating periosteum. For group I, defects were filled with a nanohydroxyapatite poly(ester urethane) scaffold soaked in PBS and left as such (group Ia) or wrapped with a tissue-engineered periosteal substitute (group Ib). For group II, an expanded-polytetrafluoroethylene (e-PTFE) (GORE-TEX ® ) membrane was inserted around the radius then the defects received either scaffold alone (group IIa) or scaffold wrapped with periosteal substitute (group IIb). Animals were euthanized after 12–16 weeks, and bone regeneration was evaluated by radiography, computed microtomography (μCT), and histology. In the first group, we observed formation of radio-ulnar synostosis irrespective of the treatment. This was completely eliminated upon placement of the e-PTFE (GORE-TEX ® ) membrane in the second group of animals. In conclusion, modification of the model using a non-resorbable e-PTFE membrane to isolate the ulna from the radius was a valuable addition allowing for objective evaluation of the tissue-engineered periosteal substitute.

  1. Multidetector-Row Computed Tomography in the Evaluation of Transjugular Intrahepatic Portosystemic Shunt Performed with Expanded-Polytetrafluoroethylene-Covered Stent-Graft

    International Nuclear Information System (INIS)

    Fanelli, Fabrizio; Bezzi, Mario; Bruni, Antonio; Corona, Mario; Boatta, Emanuele; Lucatelli, Pierleone; Passariello, Roberto

    2011-01-01

    We assessed, in a prospective study, the efficacy of multidetector spiral computed tomography (MDCT) in the evaluation of transjugular intrahepatic portosystemic shunt (TIPS) patency in patients treated with the Viatorr (Gore, Flagstaff, AZ) expanded-polytetrafluoroethylene (e-PTFE)-covered stent-graft. Eighty patients who underwent TIPS procedure using the Viatorr self-expanding e-PTFE stent-graft were evaluated at follow-up of 1, 3, 6, and 12 months with clinical and laboratory tests as well as ultrasound–color Doppler (USCD) imaging. In case of varices, upper gastrointestinal endoscopy was also performed. In addition, the shunt was evaluated using MDCT at 6 and 12 months. In all cases of abnormal findings and discrepancy between MDCT and USCD, invasive control venography was performed. MDCT images were acquired before and after injection of intravenous contrast media on the axial plane and after three-dimensional reconstruction using different algorithms. MDCT was successfully performed in all patients. No artefacts correlated to the Viatorr stent-graft were observed. A missing correlation between UCSD and MDCT was noticed in 20 of 80 (25%) patients. Invasive control venography confirmed shunt patency in 16 (80%) cases and shunt malfunction in 4 (20%) cases. According to these data, MDCT sensitivity was 95.2%; specificity was 96.6%; and positive (PPV) and negative predictive values (NPV) were 90.9 and 98.2%, respectively. USCD sensitivity was 90%; specificity was 75%; and PPV and NPV were 54.5 and 95.7%, respectively. A high correlation (K value = 0.85) between MDCT and invasive control venography was observed. On the basis of these results, MDCT shows superior sensitivity and specificity compared with USCD in those patients in whom TIPS was performed with the Viatorr stent-graft. MDCT can be considered a valid tool in the follow-up of these patients.

  2. Pregnancy Outcomes After Myomectomy With Polytetrafluoroethylene Placement

    OpenAIRE

    Eaton, Jennifer L.; Milad, Magdy P.

    2014-01-01

    Background and Objectives: The aim of this study was to report preliminary data on pregnancy outcomes after myomectomy with placement of an expanded polytetrafluoroethylene adhesion barrier membrane. Methods: In this retrospective case series, 68 women who underwent myomectomy with expanded polytetrafluoroethylene membrane placement between January 1, 2003, and December 31, 2009, were identified. Of these women, 15 subsequently had documented pregnancies and were included in the final dataset...

  3. ENHANCED HEALING OF 30-MU-M GORE-TEX PTFE MICROARTERIAL PROSTHESES BY ALCOHOL-PRETREATMENT

    NARCIS (Netherlands)

    VANDERLEI, B; STRONCK, JW; WILDEVUUR, CRH

    1991-01-01

    Polytetrafluoroethylene (PTFE) microvascular prostheses with a fibril length of 30-mu-m were pretreated with alcohol (n = 18), implanted into the abdominal aorta of rats and were evaluated at 1 day (n = 3), 1 week (n = 3), 3 weeks (n = 6) and 6 weeks (n = 6) to determine whether alcohol-pretreatment

  4. The use of expanded microporous polytetrafluoroethylene for limb salvage: a preliminary report.

    Science.gov (United States)

    Campbell, C D; Brooks, D H; Webster, M W; Bahnson, H T

    1976-05-01

    Initial laboratory and clinical evaluations of a new prosthetic material, expanded microporous polytetrafluoroethylene (PTFE), for small vessel replacement is promising and encourages further clinical trial. Frequently the autogenous saphenous vein is not available for bypass procedures, and alternative arterial substitutes have not proved reliable for replacement of small vessels. In this study, 15 patients with impending loss of limb and no available saphenous vein underwent revascularization of the lower extremity with expanded microporous PTFE grafts. Thirteen of 15 patients now demonstrate viable extremities with a resulting over-all early patency and limb salvage rate of 87 percent for this series. Follow-up ranges from one to 8 months. Seven patients had diabetes mellitus and eight had atherosclerotic heart disease. Nine grafts crossed the knee joint. In all patients arterial runoff was poor. Six patients had previous femoropopliteal bypasses, five with autogenous veins and one with Dacron velour. Two patients had multiple previous operations that failed, first with autogenous vein and later with fabric grafts. The current limb salvage and patency rate of 87 percent in high-risk patients suggests that expanded PTFE may be the prosthesis of choice when an autogenous vein is not available and possibly an equally good substitute when the venous autograft is available.

  5. Suspensão ao músculo frontal com politetrafluoretileno para o tratamento da blefaroptose Frontalis suspension with polytetrafluorethylene for the treatment of blepharoptosis

    Directory of Open Access Journals (Sweden)

    Juliana Silvério

    2009-02-01

    Full Text Available OBJETIVO: Relatar a experiência com o uso do fio de politetrafluoretileno nas cirurgias de suspensão ao músculo frontal para correção de blefaroptose. MÉTODOS: Foram estudados todos os casos de blefaroptose grave submetidos à cirurgia pela técnica de suspensão ao músculo frontal como fio de politetrafluoretileno, no período de fevereiro de 2003 a abril de 2007. Foram realizadas 36 cirurgias em 23 pacientes, a média de seguimento foi de 15,8 meses (variando de 3 a 36 meses. A técnica cirúrgica utilizada foi a descrita por Fox. RESULTADOS: Entre as causas de blefaroptose foram encontradas: congênita em 20 (86,95% pacientes, blefarofimose em 2 (8,69% pacientes e traumática em 1 (4,35% paciente. Na primeira semana de pós-operatório, 6 (26,08% pacientes referiram assimetria palpebral, 4 (17,39% notaram edema local, 3 (13,04% pacientes apresentaram granuloma no local do fio e 1 (4,35% paciente apresentou celulite facial na região frontal unilateral. Após 3 meses de seguimento, 3 (13,04% pacientes referiram assimetria palpebral, e em 1 (4,35% paciente persistia o granuloma. CONCLUSÃO: O politetrafluoretileno - Modelo CV3, 6.0 (Gore-Tex®; W.L. Gore & Associates Inc, Flagstaff, AZ, EUA é um material adequado com bons resultados funcionais (86,9%, baixos índices de complicação (4,35% e insatisfação (13,4%, podendo ser uma alternativa em relação à fáscia lata, na cirurgia de suspensão ao frontal para tratamento de ptose palpebral grave.PURPOSE: To evaluate the functional results and complications of the use of expanded polytetrafluoroethylene in frontalis suspension surgery for the treatment of blepharoptosis. METHODS: Frontalis suspension procedure with polytetrafluoroethylene was performed between 2003 and 2007 on 23 patients (36 eyes with blepharoptosis. An average follow-up time was 15.8 months (range, 3 to 36. Surgical technique used was described by Fox. RESULTS: The causes of blepharoptosis found were: congenital in

  6. Repair of large abdominal wall defects with expanded polytetrafluoroethylene (PTFE).

    Science.gov (United States)

    Bauer, J J; Salky, B A; Gelernt, I M; Kreel, I

    1987-01-01

    Most abdominal wall incisional hernias can be repaired by primary closure. However, where the defect is large or there is tension on the closure, the use of a prosthetic material is indicated. Expanded polytetrafluoroethylene (PTFE) patches were used to repair incisional hernias in 28 patients between November 1983 and December 1986. Twelve of these patients (43%) had a prior failure of a primary repair. Reherniation occurred in three patients (10.7%). Wound infections developed in two patients (7.1%), both of whom had existing intestinal stomas, one with an intercurrent pelvic abscess. The prosthetic patch was removed in the patient with the abscess, but the infection was resolved in the other without sequelae. Septic complications did not occur after any operations performed in uncontaminated fields. None of the patients exhibited any undue discomfort, wound pain, erythema, or induration. Complications related to adhesions, erosion of the patch material into the viscera, bowel obstruction, or fistula formation did not occur. Based on this clinical experience, the authors believe that the PTFE patch appears to represent an advance in synthetic abdominal wall substitutes. Images Fig. 1. Fig. 2(left)., Fig. 3(right). PMID:3689012

  7. Physicomechanical evaluation of polypropylene, polyester, and polytetrafluoroethylene meshes for inguinal hernia repair.

    Science.gov (United States)

    Deeken, Corey R; Abdo, Michael S; Frisella, Margaret M; Matthews, Brent D

    2011-01-01

    For meshes to be used effectively for hernia repair, it is imperative that engineers and surgeons standardize the terminology and techniques related to physicomechanical evaluation of these materials. The objectives of this study were to propose standard techniques, perform physicomechanical testing, and classify materials commonly used for inguinal hernia repair. Nine meshes were evaluated: 4 polypropylene, 1 polyester, 1 polytetrafluoroethylene, and 3 partially absorbable. Physical properties were determined through image analysis, laser micrometry, and density measurements. Biomechanical properties were determined through suture retention, tear resistance, uniaxial, and ball burst testing with specimens tested in 2 different orientations. A 1-way ANOVA with Tukey's post-test or a t-test were performed, with p INFINIT (WL Gore & Associates) did not resist tearing as effectively as the others. All meshes exhibited supraphysiologic burst strengths except INFINIT and ULTRAPRO. Significant differences exist between the physicomechanical properties of polypropylene, polyester, polytetrafluoroethylene, and partially absorbable mesh prostheses commonly used for inguinal hernia repair. Orientation of the mesh was also shown to be critical for the success of meshes, particularly those demonstrating anisotropy. Copyright © 2011 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

  8. A prospective study on the effectiveness of cotton versus waterproof cast padding in maintaining the reduction of pediatric distal forearm fractures.

    Science.gov (United States)

    Robert, Christopher E; Jiang, Jimmy J; Khoury, Joseph G

    2011-03-01

    Distal forearm fractures, one of the most common fractures seen in the pediatric population, are regularly treated by closed reduction and casting. Our study investigates the effectiveness of Gore-Tex-lined casting in maintaining the reduction of 100% displaced distal forearm fractures compared with traditional cotton-lined casts. We screened all patients from February 2007 to July 2009 who presented to Children's Hospital in Birmingham, AL with a distal radius fracture. Only patients with 100% displaced distal radius fractures were eligible to be assigned to either the cotton-lined or Gore-Tex-lined cast groups. Power analysis was performed to identify an adequate patient sample size. The mean maximum change between initial post-reduction x-rays and follow-up x-rays for anterior-posterior (AP) angulation, AP displacement, lateral angulation, and lateral displacement of the radius were calculated for both cotton and Gore-Tex groups. The rate of subsequent intervention and/or unacceptable results for each group was also analyzed. Seven hundred and twenty-two patients were treated with distal radius fractures at our hospital with 59 patients eligible for inclusion in our study. Thirty-six of our patients were treated with cotton-lined casts, and 23 patients were treated with Gore-Tex-lined cast. The mean maximum change in AP angulation, AP displacement, lateral angulation, and lateral displacement of the radius after initial reduction was 9.2 degrees, 6.9%, 13.9 degrees, and 13.6%, respectively, for the cotton-lined cast group and 7.7 degrees, 6.1%, 14.6 degrees, and 9.6%, respectively, for the Gore-Tex-lined cast group. There were no statistical differences between the means of the 4 measurements (P=0.33, 0.69, 0.73, and 0.10, respectively). There were also no significant differences between groups for final AP and lateral angulation and displacement. Subgroup analysis showed no significant differences in all measurements between cotton and Gore-Tex groups. Gore-Tex

  9. Laparoscopic diaphragmatic hernia repair using expanded polytetrafluoroethylene (ePTFE) for delayed traumatic diaphragmatic hernia.

    Science.gov (United States)

    Jee, Yeseob

    2017-06-01

    Traumatic diaphragmatic hernia (TDH) is an uncommon surgical problem, and diagnosis is often delayed. However, the mortality from bowel necrosis can reach 80%. Therefore, suspicion is needed and surgery is required to prevent complications. A 50-year-old man was transferred due to abdominal pain and vomiting. Chest X-ray and computed tomography (CT) scan showed herniation of the stomach through the left diaphragm. The patient had fallen down 15 months ago and CT scan at that time revealed a small defect of the diaphragm without herniation. We diagnosed delayed herniation of TDH and the patient underwent laparoscopic repair using an expanded polytetrafluoroethylene (ePTFE) mesh. Recovery was uneventful and the CT scan at 3 months after the operation showed no recurrence. We reported a delayed presenting TDH and considered a laparoscopic approach to be safe and feasible during elective surgery. Moreover, use of an ePTFE mesh for repair of large diaphragmatic hernia was also feasible.

  10. A comparison of woven versus nonwoven polypropylene (PP) and expanded versus condensed polytetrafluoroethylene (PTFE) on their intraperitoneal incorporation and adhesion formation.

    Science.gov (United States)

    Raptis, Dimitri Aristotle; Vichova, Barbora; Breza, Jan; Skipworth, James; Barker, Stephen

    2011-07-01

    To compare known and novel synthetic materials useful for incisional hernia repair and to test independently, whether they justify common perceptions related to their use. Four types of synthetic materials were implanted in to 12 pigs to compare incorporation histology and adhesion formation 90 d after placement. Woven polypropylene (WPP), nonwoven polypropylene (NWPP), expanded polytetrafluoroethylene (ePTFE). and condensed polytetrafluoroethylene (cPTFE) were placed intraperitoneally (IP). Intraperitoneally, WPP became fully peritonealized, but generated thick and plentiful adhesions. NWPP became fully peritonealized and generated filmy and far less numerous adhesions. ePTFE formed some filmy adhesions and did not peritonealize. cPTFE and WPP became fully peritonealized. However, bowel became adherent on raised edges of cPTFE and WPP. We conclude that NWPP incorporates extremely well intraperitoneally, promotes few adhesions, and its use is likely to be suitable for hernia repair. cPTFE performs well and promotes few adhesions, but to minimize potentially serious complications, its edges must be secured around its entire circumference. Copyright © 2011 Elsevier Inc. All rights reserved.

  11. The Gore/Bush Records on Higher Education.

    Science.gov (United States)

    Walters, Ronald

    2000-01-01

    Compares the records of presidential candidates George W. Bush and Al Gore on higher education issues and, specifically, those of interest to the Black community. Concludes that Al Gore's record makes him an overall better choice in the 2000 campaign. (DB)

  12. Heparin-bonded, expanded polytetrafluoroethylene-lined stent graft in the treatment of femoropopliteal artery disease: 1-year results of the VIPER (Viabahn Endoprosthesis with Heparin Bioactive Surface in the Treatment of Superficial Femoral Artery Obstructive Disease) trial.

    Science.gov (United States)

    Saxon, Richard R; Chervu, Arun; Jones, Paul A; Bajwa, Tanvir K; Gable, Dennis R; Soukas, Peter A; Begg, Richard J; Adams, John G; Ansel, Gary M; Schneider, Darren B; Eichler, Charles M; Rush, Michael J

    2013-02-01

    To evaluate the performance of a heparin-bonded, expanded polytetrafluoroethylene (ePTFE)-lined nitinol endoprosthesis in the treatment of long-segment occlusive disease of the femoropopliteal artery (FPA) and to identify factors associated with loss of patency. In a single-arm, prospective, 11-center study (VIPER [Gore Viabahn Endoprosthesis with Heparin Bioactive Surface in the Treatment of Superficial Femoral Artery Obstructive Disease] trial), 119 limbs (113 patients; 69 men; mean age, 67 y), including 88 with Rutherford category 3-5 disease and 72 with Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASC II) C or D lesions of the FPA, underwent stent graft implantation. The mean lesion length was 19 cm; 56% of lesions were occlusions. Follow-up evaluations included color duplex ultrasonography in all patients, with patency defined as a peak systolic velocity ratio20% was 70% (P = .047). Primary patency was not significantly affected by device diameter (5 vs 6 vs 7 mm) or lesion length (≤20 cm vs>20 cm). The 30-day major adverse event rate was 0.8%. The heparin-bonded, ePTFE/nitinol stent graft provided clinical improvement and a primary patency rate of 73% at 1 year in the treatment of long-segment FPA disease. Careful sizing of the device relative to vessel landing zones is essential for achieving optimal outcomes. Copyright © 2013 SIR. Published by Elsevier Inc. All rights reserved.

  13. Diaphragm Repair with a Novel Cross-Linked Collagen Biomaterial in a Growing Rabbit Model.

    Directory of Open Access Journals (Sweden)

    Steffi Mayer

    Full Text Available Neonates with congenital diaphragmatic hernia and large defects often require patch closure. Acellular collagen matrices (ACM have been suggested as an alternative to synthetic durable patches as they are remodeled by the host or could also be used for tissue engineering purposes.2.0x1.0 cm diaphragmatic defects were created in 6-weeks old New-Zealand white rabbits. We compared reconstruction with a purpose-designed cross-linked ACM (Matricel to 4-layer non-cross-linked small intestinal submucosa (SIS and a 1-layer synthetic Dual Mesh (Gore-Tex. Unoperated animals or animals undergoing primary closure (4/0 polyglecaprone served as age-matched controls. 60 (n = 25 resp. 90 (n = 17 days later, animals underwent chest x-ray and obduction for gross examination of explants, scoring of adhesion and inflammatory response. Also, uniaxial tensiometry was done, comparing explants to contralateral native diaphragmatic tissue.Overall weight nearly doubled from 1,554±242 g at surgery to 2,837±265 g at obduction (+84%. X-rays did show rare elevation of the left diaphragm (SIS = 1, Gore-Tex = 1, unoperated control = 1, but no herniation of abdominal organs. 56% of SIS and 10% of Matricel patches degraded with visceral bulging in four (SIS = 3, Matricel = 1. Adhesion scores were limited: 0.5 (Matricel to 1 (SIS, Gore-Tex to the left lung (p = 0.008 and 2.5 (Gore-Tex, 3 (SIS and 4 (Matricel to the liver (p<0.0001. Tensiometry revealed a reduced bursting strength but normal compliance for SIS. Compliance was reduced in Matricel and Gore-Tex (p<0.01. Inflammatory response was characterized by a more polymorphonuclear cell (SIS resp. macrophage (Matricel type of infiltrate (p<0.05. Fibrosis was similar for all groups, except there was less mature collagen deposited to Gore-Tex implants (p<0.05.Matricel induced a macrophage-dominated inflammatory response, more adhesions, had appropriate strength but a lesser compliance compared to native tissue. The herein

  14. Student Town Meeting with Vice President Al Gore. Teacher's Guide.

    Science.gov (United States)

    Edwards, Amy N.

    This teacher's guide accompanies a videotape of the same name. Vice President Albert Gore, Jr., discusses current issues with students who question Mr. Gore on such topics as the environment, reinventing government, voter participation, crime, and the United States' role in foreign affairs. Gore tailors his answers to the teenage audience as the…

  15. The use of expanded polytetrafluoroethylene in depressed deformities of the face.

    Science.gov (United States)

    Liu, Xiaowei; Zhang, Yiming; Wang, Shaoliang; Lei, Zeyuan; Li, Xiang; Fan, Dongli

    2016-11-01

    Expanded polytetrafluoroethylene (ePTFE) has been extensively used for facial soft tissue augmentation procedures, and is regarded as safe and reliable and suitable as a permanent implant. This implant is generally used in the lower third of the face for lips filling, nasal augmentation, nasolabial folds and chin augmentation, and rarely for congenital or acquired depressed deformities of the face. The aim of the present study was to assess the effects of ePTFE in congenital or acquired depressed deformities of the face. From September, 2008 to January, 2014, 26 patients were implanted with the material ePTFE to correct depressed deformities of the face. The average age at operation was 23.2 years, with a range of 17-45 years. The depressed deformities were lateralized. The follow-up period was 6-18 months (average 9 months). The etiologies of the depressed deformities included stable hemifacial atrophy (3 cases), craniofacial microsomia (13 cases), bony depression after trauma (8 cases), and other unclear reasons (2 cases). The operations were performed under local anesthesia. ePTFE was inserted in different tissue planes that varied among the different subanatomical areas in the face: beneath the superficial temporal fascia in the temporal area, and on the surface of the superficial musculoaponeurotic system in the zygomatic area, cheek and mandibular area. All of the patients were followed up. Most of the patients [25 of 26 patients (96.2%)] were satisfied with the results, while 1 patient (3.8%) was not satisfied for incomplete correction of the depressed deformity. In conclusion, aside from lipofilling and a free flap transfer, the results showed that ePTFE was an alternative treatment for facial depressed deformity.

  16. Development of Aluminum-Lithium 2195 Gores by the Stretch Forming Process

    Science.gov (United States)

    Volz, M. P.; Chen, P. S.; Gorti, S.; Salvail, P.

    2014-01-01

    Aluminum-Lithium alloy 2195 exhibits higher mechanical properties and lower density than aluminum alloy 2219, which is the current baseline material for Space Launch System (SLS) cryogenic tank components. Replacement of Al 2219 with Al-Li 2195 would result in substantial weight savings, as was the case when this replacement was made on the shuttle external tank. A key component of cryogenic tanks are the gores, which are welded together to make the rounded ends of the tanks. The required thicknesses of these gores depend on the specific SLS configuration and may exceed the current experience base in the manufacture of such gores by the stretch forming process. Here we describe the steps taken to enhance the formability of Al-Li 2195 by optimizing the heat treatment and stretch forming processes for gore thicknesses up to 0.75", which envelopes the maximum expected gore thicknesses for SLS tanks. An annealing treatment, developed at Marshall Space Flight Center, increased the forming range and strain hardening exponent of Al-Li 2195 plates. Using this annealing treatment, one 0.525" thick and two 0.75" thick gores were manufactured by the stretch forming process. The annealing treatment enabled the stretch forming of the largest ever cross sectional area (thickness x width) of an Al-Li 2195 plate achieved by the manufacturer. Mechanical testing of the gores showed greater than expected ultimate tensile strength, yield strength, modulus, and elongation values. The gores also exhibited acceptable fracture toughness at room and LN2 temperatures. All of the measured data indicate that the stretch formed gores have sufficient material properties to be used in flight domes.

  17. 33 CFR 110.77 - Amistad Reservoir, Tex.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Amistad Reservoir, Tex. 110.77... ANCHORAGE REGULATIONS Special Anchorage Areas § 110.77 Amistad Reservoir, Tex. (a) Diablo East, Tex. That portion of the Amistad Reservoir enclosed by a line connecting the following points, excluding a 300-foot...

  18. Endovascular Treatment of Occlusive Lesions in the Aortic Bifurcation with Kissing Polytetrafluoroethylene-Covered Stents

    NARCIS (Netherlands)

    Grimme, F.A.B.; Spithoven, J.H.; Zeebregts, C.J.A.; Scharn, D.M.; Reijnen, M.M.

    2015-01-01

    PURPOSE: To determine the clinical outcomes of polytetrafluoroethylene covered balloon expandable stents (CBESs) in occlusive lesions of the aortic bifurcation in a kissing stent configuration. MATERIALS AND METHODS: The study included 69 consecutive patients (29 men, 40 women) who underwent kissing

  19. Endovascular Treatment of Occlusive Lesions in the Aortic Bifurcation with Kissing Polytetrafluoroethylene-Covered Stents

    NARCIS (Netherlands)

    Grimme, Frederike A. B.; Spithoven, J. Hans; Zeebregts, Clark J.; Scharn, Dirk M.; Reijnen, Michel M. P. J.

    Purpose: To determine the clinical outcomes of polytetrafluoroethylene covered balloon expandable stents (CBESs) in occlusive lesions of the aortic bifurcation in a kissing stent configuration. Materials and Methods: The study included 69 consecutive patients (29 men, 40 women) who underwent kissing

  20. Quantification of deposition of neutrophilic granulocytes on vascular grafts in dogs with 111In-labeled granulocytes

    International Nuclear Information System (INIS)

    Dewanjee, M.K.; Solis, E.; Mackey, S.T.; Socher, S.; Chowdhury, S.; Wu, F.P.; Kaye, M.P.

    1985-01-01

    A new radioisotopic technique has been developed for quantification of deposition of neutrophilic granulocytes on vascular grafts. Nine healthy mongrel dogs underwent bilateral femoral artery resection and reconstruction with grafts of the femoral vein and Gore-Tex. Pure granulocytes that had been separated from whole blood by centrifugal elutriation were labeled with 111 In-tropolone in plasma. The granulocyte harvesting efficiency was 25 +/- 12%, and the labeling efficiency was 87 +/- 7%. Three hours after injection of labeled granulocytes and 2 hours after reperfusion, the grafts were harvested and cut into several segments for study of areas of anastomoses and midsections. On the basis of the radioactivity in the blood and in anastomotic and graft sections, the area of graft sections, and the neutrophilic granulocyte and differential leukocyte counts, the number of neutrophilic granulocytes adherent to a unit area and the total number of neutrophilic granulocytes on graft sections were calculated. These quantifications of the deposition of neutrophilic granulocytes indicated that the midsections of Gore-Tex grafts retained more neutrophilic granulocytes than did the midsections of vein grafts. Although the anastomotic areas retained more neutrophilic granulocytes than did the midsections of vein grafts, the opposite finding prevailed for the Gore-Tex grafts. A major fraction of neutrophilic granulocytes on Gore-Tex grafts was incorporated into the thrombus. Semiquantitative information obtained by scintigraphy of the deposition of neutrophilic granulocytes on vascular grafts also confirmed this observation

  1. StarTeX - a TeX for beginners

    OpenAIRE

    Langmyhr, Dag

    1996-01-01

    This article describes StarTEX, a new TEX format for students writing their first report and other novice users. Its aim is to provide a simpler and more robust tool for users with no previous knowledge of TEX and LATEX.V

  2. Sustained Thromboresistant Bioactivity with Reduced Intimal Hyperplasia of Heparin-Bonded Polytetrafluoroethylene Propaten Graft in a Chronic Canine Femoral Artery Bypass Model.

    Science.gov (United States)

    Freeman, John; Chen, Aaron; Weinberg, Roy J; Okada, Tamuru; Chen, Changyi; Lin, Peter H

    2018-05-01

    Bypass graft thrombosis remains a significant mode of failure in prosthetic graft revascularization. The purpose of this investigation was to evaluate the long-term thromboresistant effect of heparin-bonded expanded polytetrafluoroethylene (ePTFE) graft using Carmeda BioActive Surface technology in a canine model. Bilateral femorofemoral artery bypass grafts with ePTFE grafts were performed in 25 adult grayhound dogs. In each animal, a heparin-bonded ePTFE graft (Propaten, WL Gore) was placed on one side, whereas a control nonheparin graft was placed on the contralateral side. The graft patency was assessed at 1, 6, 12, 18, and 24 months (n = 5 per group) following the bypass. Heparin bioactivity of the graft material was analyzed. The effect of intimal hyperplasia was also assessed. All bypass grafts were patent at 1 month. Significantly greater patency rates were noted in the Propaten group compared to the control group at 12, 18, and 24 months, which were 84%, 80%, and 80% vs. 55%, 35%, and 20%, respectively (P  0.05). Heparin-bonded ePTFE graft provides a thromboresistant surface and reduced anastomotic intimal hyperplasia at 2 years. The stable heparin bioactivity of the Propaten graft confers an advantage in long-term graft patency. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  3. Truth and opinion in climate change discourse: the Gore-Hansen disagreement.

    Science.gov (United States)

    Russill, Chris

    2011-11-01

    In this paper, I discuss the "inconvenient truth" strategy of Al Gore. I argue that Gore's notion of truth upholds a conception of science and policy that narrows our understanding of climate change discourse. In one notable exchange, Gore and NASA scientist, James Hansen, disagreed about whether scientific statements based on Hansen's computer simulations were truth or opinion. This exchange is featured in An Inconvenient Truth, yet the disagreement is edited from the film and presented simply as an instance of Hansen speaking "inconvenient truth". In this article, I compare the filmic representation of Hansen's testimony with the congressional record. I place their exchange in a broader historical perspective on climate change disputation in order to discuss the implications of Gore's perspective on truth.

  4. Aluminum 2195 T8 Gore Development for Space Launch System Core and Upper Stage

    Science.gov (United States)

    Volz, Martin

    2015-01-01

    Gores are pie-shaped panels that are welded together to form the dome ends of rocket fuel tanks as shown in figure 1. Replacing aluminum alloy 2219 with aluminum (Al)-lithium (Li) alloy 2195 as the Space Launch System (SLS) cryogenic tank material would save enormous amounts of weight. In fact, it has been calculated that simply replacing Al 2219 gores with Al 2195 gores on the SLS core stage domes could save approximately 3,800 pound-mass. This is because the Al-Li 2195 alloy exhibits both higher mechanical properties and lower density than the SLS baseline Al 2219 alloy. Indeed, the known advantages of Al 2195 led to its use as a replacement for Al 2219 in the shuttle external tank program. The required thicknesses of Al 2195 gores for either SLS core stage tanks or upper stage tanks will depend on the specific design configurations. The required thicknesses or widths may exceed the current experience base in the manufacture of such gores by the stretch-forming process. Accordingly, the primary objective of this project was to enhance the formability of Al 2195 by optimizing the heat treatment and stretch-forming process for gore thicknesses up to 0.75 inches, which envelop the maximum expected gore thicknesses for SLS tank configurations.

  5. The Effectiveness of Texas Teacher Certification Programs as Evidenced through Pass Rates on TExES PPR 160 Exam

    Science.gov (United States)

    Clouse, Scarlet

    2013-01-01

    The purpose of this study was to investigate the differences between alternative certification pathways, specifically those offered through a university-based, post baccalaureate certification program and a regional education service center certification program. A quantitative research design was implemented and archived scores on the TExES PPR…

  6. Recent Seismicity in Texas and Research Design and Progress of the TexNet-CISR Collaboration

    Science.gov (United States)

    Hennings, P.; Savvaidis, A.; Rathje, E.; Olson, J. E.; DeShon, H. R.; Datta-Gupta, A.; Eichhubl, P.; Nicot, J. P.; Kahlor, L. A.

    2017-12-01

    The recent increase in the rate of seismicity in Texas has prompted the establishment of an interdisciplinary, interinstitutional collaboration led by the Texas Bureau of Economic Geology which includes the TexNet Seismic Monitoring and Research project as funded by The State of Texas (roughly 2/3rds of our funding) and the industry-funded Center for Integrated Seismicity Research (CISR) (1/3 of funding). TexNet is monitoring and cataloging seismicity across Texas using a new backbone seismic network, investigating site-specific earthquake sequences by deploying temporary seismic monitoring stations, and conducting reservoir modeling studies. CISR expands TexNet research into the interdisciplinary realm to more thoroughly study the factors that contribute to seismicity, characterize the associated hazard and risk, develop strategies for mitigation and management, and develop methods of effective communication for all stakeholders. The TexNet-CISR research portfolio has 6 themes: seismicity monitoring, seismology, geologic and hydrologic description, geomechanics and reservoir modeling, seismic hazard and risk assessment, and seismic risk social science. Twenty+ specific research projects span and connect these themes. We will provide a synopsis of research progress including recent seismicity trends in Texas; Fort Worth Basin integrated studies including geological modeling and fault characterization, fluid injection data syntheses, and reservoir and geomechanical modeling; regional ground shaking characterization and mapping, infrastructure vulnerability assessment; and social science topics of public perception and information seeking behavior.

  7. Bioactive nanocomposite for chest-wall replacement: Cellular response in a murine model.

    Science.gov (United States)

    Jungraithmayr, Wolfgang; Laube, Isabelle; Hild, Nora; Stark, Wendelin J; Mihic-Probst, Daniela; Weder, Walter; Buschmann, Johanna

    2014-07-01

    Chest-wall invading malignancies usually necessitate the resection of the respective part of the thoracic wall. Gore-Tex® is the material of choice that is traditionally used to repair thoracic defects. This material is well accepted by the recipient; however, though not rejected, it is an inert material and behaves like a 'foreign body' within the thoracic wall. By contrast, there are materials that have the potential to physiologically integrate into the host, and these materials are currently under in vitro and also in vivo investigation. These materials offer a gradual but complete biodegradation over time, and severe adverse inflammatory responses can be avoided. Here, we present a novel material that is a biodegradable nanocomposite based on poly-lactic-co-glycolic acid and amorphous calcium phosphate nanoparticles in comparison to the traditionally employed Gore-Tex® being the standard for chest-wall replacement. On a mouse model of thoracic wall resection, that resembles the technique and localization applied in humans, poly-lactic-co-glycolic acid and amorphous calcium phosphate nanoparticles and Gore-Tex® were implanted subcutaneously and additionally tested in a separate series as a chest-wall graft. After 1, 2, 4 and 8 weeks cell infiltration into the respective materials, inflammatory reactions as well as neo-vascularization (endothelial cells) were determined in six different zones. While Gore-Tex® allowed for cell infiltration only at the outer surface, electrospun poly-lactic-co-glycolic acid and amorphous calcium phosphate nanoparticles were completely penetrated by infiltrating cells. These cells were composed mainly by macrophages, with only 4% of giant cells and lymphocytes. Total macrophage count increased by time while the number of IL1-β-expressing macrophages decreased, indicating a protective state towards the graft. As such, poly-lactic-co-glycolic acid and amorphous calcium phosphate nanoparticles seem to develop ideal

  8. An Experimental Study to Replace the Thoracic Descending Aorta for Pigs with a Self-Made Sutureless Blood Vessel

    Directory of Open Access Journals (Sweden)

    Fenglin Song

    2014-01-01

    Full Text Available To simplify the procedure of blood vessel replacement operation and shorten the vascular anastomosis time, we developed a special artificial blood vessel which can be connected to native blood vessels without suture. The self-made sutureless blood vessel (SMSBV was made from two titanium connectors and a Gore-Tex graft. To investigate blood compatibility and histocompatibility of the SMSBV, we carried thoracic descending aorta replacement using either SMSBV or Gore-Tex, respectively, in pigs. The aortic clamp time and the operative blood loss in the experimental group (using SMSBV were less than those in the control group (using Gore-Tex. The whole blood hematocrit, platelet count, plasma soluble P-selectin, plasma free hemoglobin, and interleukins 2, 6 at each time point were not different significantly between the two groups. Light microscopy and transmission electron microscopy examination showed there were layers of vascular smooth muscle cells and endothelial cells adhered in the inner wall of artificial blood vessel without any signs of thrombosis. Based on the result, we have drawn the conclusion that the application of SMSBV can significantly shorten the vascular anastomosis time, reduce operative blood loss, and show good blood and tissue compatibility.

  9. Thoracoscopic phrenic nerve patch insulation to avoid phrenic nerve stimulation with cardiac resynchronization therapy

    Directory of Open Access Journals (Sweden)

    Masatsugu Nozoe, MD, PhD

    2014-04-01

    Full Text Available A 76-year-old female was implanted with a cardiac resynchronization therapy (CRT device, with the left ventricular lead implanted through a transvenous approach. One day after implantation, diaphragmatic stimulation was observed when the patient was in the seated position, which could not be resolved by device reprogramming. We performed thoracoscopic phrenic nerve insulation using a Gore-Tex patch. The left phrenic nerve was carefully detached from the pericardial adipose tissue, and a Gore-Tex patch was inserted between the phrenic nerve and pericardium using a thoracoscopic technique. This approach represents a potential option for the management of uncontrollable phrenic nerve stimulation during CRT.

  10. Al Gore attends Fall Meeting session on Earth observing satellite

    Science.gov (United States)

    Richman, Barbara T.

    2011-12-01

    Former U.S. vice president Al Gore, making unscheduled remarks at an AGU Fall Meeting session, said, "The reason you see so many pictures" of the Deep Space Climate Observatory (DSCOVR) satellite at this session is "that it already has been built." However, "because one of its primary missions was to help document global warming, it was canceled. So for those who are interested in struggling against political influence," Gore said, "the benefits have been documented well here." Gore made his comments after the third oral presentation at the 8 December session entitled "Earth Observations From the L1 (Lagrangian Point No. 1)," which focused on the capabilities of and progress on refurbishing DSCOVR. The satellite, formerly called Triana, had been proposed by Gore in 1998 to collect climate data. Although Triana was built, it was never launched: Congress mandated that before the satellite could be sent into space the National Academies of Science needed to confirm that the science it would be doing was worthwhile. By the time the scientific validation was complete, the satellite "was no longer compatible with the space shuttle manifest," Robert C. Smith, program manager for strategic integration at the NASA Goddard Space Flight Center, told Eos.

  11. MODE-PP TeX: A GRM/GDMO Pretty Printing Library based on MODE-FE for the Generation of TeX Documents : Release 1.0 Reference Manual

    OpenAIRE

    Festor , Olivier

    1996-01-01

    MODE-PP TeX (MODE TeX Pretty-Printer) is a module which allows formatting and pretty printing of GRM (General Relationship Model) and GDMO (Guidelines for the Definition of Managed Objects) specifications. The tool allows the generation of one or more TeX files which contain formatted specifications according to different document style constrains. MODE-PP TeX is part of the MODE (Managed Object Development Environment) prototype which is developed for integrating the use of Formal Descriptio...

  12. Histologic Changes of Implanted Gore Bio-A in an Experimental Animal Model

    Directory of Open Access Journals (Sweden)

    Kwan Koo Yeo

    2014-01-01

    Full Text Available Gore Bio-A has been reported to be an ideal synthetic bioabsorbable scaffold material for hernia repair. The purpose of this study was to determine the effectiveness of Gore Bio-A in soft tissue augmentation. Six New Zealand white rabbits were used in the study. Five subcutaneous pockets were created on the back of the rabbit, and 20×20 mm sized square shaped Gore Bio-A sheets, each 1.5 mm, 3 mm, 4.5 mm, 6 mm, and 7.5 mm in thickness, were implanted into each pocket (1 layer to 5 layers. To analyze the morphologic and histologic changes, the implants were harvested 1, 3, and 6 months after implantation. Following the gross analysis, absorption rate was accelerated with increased implant duration and decreased thickness. Histological analysis of the implants demonstrated progressive neovascularization, fibroblast infiltration, and neocollagenation over time. Six months after implantation, Gore Bio-A was almost absorbed and degenerated, not maintaining its volume. Based on this study, Gore Bio-A was revealed as a biocompatible material; however, it is not suitable for soft tissue augmentation because it is absorbed in the process of changing into soft tissue without maintaining its own volume. Therefore, this material is incomplete and needs more study to overcome this limitation.

  13. Bush and Gore Focus on Schools.

    Science.gov (United States)

    Joiner, Lottie L.

    2000-01-01

    In the 2000 presidential race, education seems a top priority for Vice-President Al Gore and Texas Governor George W. Bush. Although both candidates are promising billions of federal-aid dollars to raise standards, many believe they are ignoring factors such as student motivation and funding inequities. (MLH)

  14. Gore offers to help drug companies pursue research.

    Science.gov (United States)

    1996-03-08

    A meeting convened between Vice President Al Gore and executives of leading pharmaceutical companies to determine means of accelerating efforts to develop vaccines, therapeutics, and microbicides for people with HIV. Gore explained that the administration will work with pharmaceutical companies to determine the long-term effectiveness of drugs approved by the Food and Drug Administration (FDA), work with international groups to increase investment in vaccine development, help develop new microbicides for women with HIV, and identify promising areas of AIDS research. According to advocates, the Clinton Administration has made great strides in improving and accelerating the FDA's drug approval process. The next goal of the pharmaceutical research agenda should be to include consumer advocates in the decision-making process.

  15. Neurosurgical considerations after bull goring during festivities in Spain and Latin America.

    Science.gov (United States)

    Spiotta, Alejandro M; Matoses, Salvador Martorell

    2011-08-01

    Bullfighting is a highly popular activity during festivities in Spain and Latin America. A scientific society for bullfight injuries, Congreso Internacional de Cirugía Taurina, was founded on November 24, 1974, in recognition of the distinctive pattern of injury that results from bull goring, and a subspecialty of general surgical trauma with emphasis on the acute surgical management of bull-goring injuries has emerged. Injuries to the head and neck are less frequent than genitourinary, inguinal, and abdominal injuries, but are more severe and more likely to result in death. This report reviews the primary venues in which bull goring and associated injuries occur, including the bullfight and the running of the bulls. The biomechanics of the primary and secondary goring injuries are reviewed, with an emphasis on those with the potential to result in neurosurgical injuries. This results in a very unique and devastating pattern of injury that combines penetrating and blunt mechanisms and results in polytrauma. Neurosurgical expertise should be immediately available on-site in the event of a life-threatening neurological injury.

  16. Gore's Controversial Priorities for Higher Education.

    Science.gov (United States)

    Gose, Ben

    2000-01-01

    Evaluates presidential candidate Al Gore's priorities for higher education, noting criticism by some educators of his emphasis on benefits for the middle class and the large number of specific proposals he has offered, including the College Opportunity Tax Cut, 21st Century Teachers' Corps, 401(j) Educational Savings Accounts, the National Tuition…

  17. Transjugular Intrahepatic Portosystemic Shunt Flow Reduction with Adjustable Polytetrafluoroethylene-Covered Balloon-Expandable Stents Using the “Sheath Control” Technique

    Energy Technology Data Exchange (ETDEWEB)

    Blue, Robert C., E-mail: Robert.c.blue@gmail.com; Lo, Grace C.; Kim, Edward; Patel, Rahul S.; Scott Nowakowski, F.; Lookstein, Robert A.; Fischman, Aaron M. [Icahn School of Medicine at Mount Sinai, Interventional Radiology Section, Department of Radiology (United States)

    2016-06-15

    PurposeA complication of transjugular intrahepatic portosystemic shunts (TIPS) placement is refractory portosystemic encephalopathy (PSE) often requiring TIPS reduction. We report the results of a “sheath control technique” utilizing constraining sheaths during deployment of polytetrafluoroethylene (PTFE)-covered balloon-expandable stents, minimizing stent migration, and providing additional procedural control.MethodsTIPS reduction was performed in 10 consecutive patients for PSE using Atrium iCast covered stents (Atrium Maquet Getinge Group, Germany). Within the indwelling TIPS stent, a 9 mm × 59 mm iCast stent was deployed with 2 cm exposed from the sheath’s distal end and the majority of the stent within the sheath to create the distal hourglass shape. During balloon retraction, the stent was buttressed by the sheath. The proximal portion of the stent was angioplastied to complete the hourglass configuration, and the central portion of the stent was dilated to 5 mm. Demographics, pre- and post-procedure laboratory values, and outcomes were recorded.ResultsTen patients underwent TIPS reduction with 100 % technical success. There was no stent migration during stent deployment. All patients experienced initial improvement of encephalopathy. One patient ultimately required complete TIPS occlusion for refractory PSE, and another developed TIPS occlusion 36 days post-procedure. There was no significant trend toward change in patients’ MELD scores immediately post-procedure or at 30 days (p = 0.46, p = 0.47, respectively).ConclusionTIPS reduction using Atrium iCast PTFE balloon-expandable stents using the “sheath control technique” is safe and effective, and minimizes the risk of stent migration.

  18. 76 FR 8774 - Granular Polytetrafluoroethylene Resin From Japan

    Science.gov (United States)

    2011-02-15

    ... INTERNATIONAL TRADE COMMISSION [Investigation No. 731-TA-386 (Third Review)] Granular Polytetrafluoroethylene Resin From Japan AGENCY: United States International Trade Commission. ACTION: Termination of five... revocation of the antidumping duty order on granular polytetrafluoroethylene resin from Japan would be likely...

  19. TEX-2 - experimental reports 1996

    International Nuclear Information System (INIS)

    Brokmeier, H.-G.; Witassek, B.

    1997-01-01

    In 1996 the FRG-1 has been operated during 262 days. Hence, numerous investigations on about 26 different projects were carried out at TEX-2. This report gives a short description of these projects. Beam time was given at about 50% for geological projects and about 50% for materials science projects. The different samples measured at TEX-2 represent a broad spectrum: Magnetite, hematite, gypsum, calcite, halite, galena, YBaCuO-superconductures, niobium, copper, titanium aluminides, intermetallic NiAl, composites (Fe-Cu, Al-Mg, Al-Nb, Cu-Mg, Ag-Ni) and zircaloy. Instrumental improvements were carried out at the loading device, at special sample holders and at the slit system. (orig.) [de

  20. Valuable books from the library of Paul Gore (Identification and/or inventory of sources

    Directory of Open Access Journals (Sweden)

    Maria Danilov

    2013-12-01

    Full Text Available Paul Gore (1875-1927 - an outstanding figure of the socio-political, scientific and cultural life of Bessarabia at the beginning of 20th century, was also known among his contemporaries as a keen collector of old and rare books. Undoubtedly, the most valuable part of the library of Paul Gore consisted of books on the history of Bessarabia. Documents from the National Archives of the Republic of Moldova in Chişinău confirm that he inherited a large part of books from his father Gheorghe Gore (1839-1909. A study of the Paul Gore Fund at the National Archives of Romania in Bucharest gave us a lot of documentary evidence of the destiny of this Bessarabian noble library, which later became a property of the King Ferdinand Fund. However, the fate of its most valuable part - books on the history of Bessarabia, consisted of 651 units of the total number of 6456 volumes - is still unknown.

  1. KneeTex: an ontology-driven system for information extraction from MRI reports.

    Science.gov (United States)

    Spasić, Irena; Zhao, Bo; Jones, Christopher B; Button, Kate

    2015-01-01

    In the realm of knee pathology, magnetic resonance imaging (MRI) has the advantage of visualising all structures within the knee joint, which makes it a valuable tool for increasing diagnostic accuracy and planning surgical treatments. Therefore, clinical narratives found in MRI reports convey valuable diagnostic information. A range of studies have proven the feasibility of natural language processing for information extraction from clinical narratives. However, no study focused specifically on MRI reports in relation to knee pathology, possibly due to the complexity of knee anatomy and a wide range of conditions that may be associated with different anatomical entities. In this paper we describe KneeTex, an information extraction system that operates in this domain. As an ontology-driven information extraction system, KneeTex makes active use of an ontology to strongly guide and constrain text analysis. We used automatic term recognition to facilitate the development of a domain-specific ontology with sufficient detail and coverage for text mining applications. In combination with the ontology, high regularity of the sublanguage used in knee MRI reports allowed us to model its processing by a set of sophisticated lexico-semantic rules with minimal syntactic analysis. The main processing steps involve named entity recognition combined with coordination, enumeration, ambiguity and co-reference resolution, followed by text segmentation. Ontology-based semantic typing is then used to drive the template filling process. We adopted an existing ontology, TRAK (Taxonomy for RehAbilitation of Knee conditions), for use within KneeTex. The original TRAK ontology expanded from 1,292 concepts, 1,720 synonyms and 518 relationship instances to 1,621 concepts, 2,550 synonyms and 560 relationship instances. This provided KneeTex with a very fine-grained lexico-semantic knowledge base, which is highly attuned to the given sublanguage. Information extraction results were evaluated

  2. Election 2000: The Keys Point to Gore.

    Science.gov (United States)

    Lichtman, Allan J.

    2000-01-01

    Asserts that Vice President Al Gore will be elected in 2000 based on the performance of the Clinton administration. Utilizes the key to the White House, 13 true-or-false diagnostic questions stated as propositions. If five or less are false then the party in power wins. (CMK)

  3. 77 FR 50486 - Application To Export Electric Energy; TexMex Energy, LLC

    Science.gov (United States)

    2012-08-21

    ... DEPARTMENT OF ENERGY [OE Docket No. EA-294-B] Application To Export Electric Energy; TexMex Energy.... SUMMARY: TexMex Energy, LLC (TexMex) has applied to renew its authority to transmit electric energy from...Mex to transmit electric energy from the United States to Mexico as a power marketer for a five-year...

  4. Effect of Graft Material on Red Blood Cell Loss Following Aortic Surgery

    National Research Council Canada - National Science Library

    Fisher, Jay

    1990-01-01

    ... (Meadox Woven Double Velour) and PTFE (Gore-Tex) grafts. A total of 25 patients (13 Dacron, 12 PTFE) were studied including 21 with abdominal aortic aneurysms, and 4 with aorto-iliac occlusive disease...

  5. Congenital heart defect corrective surgeries

    Science.gov (United States)

    ... make it bigger with a patch made of Gore-tex, a man-made (synthetic) material. Another way ... 434. Bhatt AB, Foster E, Kuehl K, et al; American Heart Association Council on Clinical Cardiology. Congenital ...

  6. Thoracoscopic phrenic nerve patch insulation to avoid phrenic nerve stimulation with cardiac resynchronization therapy

    OpenAIRE

    Nozoe, Masatsugu; Tanaka, Yasuaki; Koyama, Junjiroh; Oshitomi, Takashi; Honda, Toshihiro; Yoshioka, Masakazu; Iwatani, Kazunori; Hirayama, Touitsu; Nakao, Koichi

    2014-01-01

    A 76-year-old female was implanted with a cardiac resynchronization therapy (CRT) device, with the left ventricular lead implanted through a transvenous approach. One day after implantation, diaphragmatic stimulation was observed when the patient was in the seated position, which could not be resolved by device reprogramming. We performed thoracoscopic phrenic nerve insulation using a Gore-Tex patch. The left phrenic nerve was carefully detached from the pericardial adipose tissue, and a Gore...

  7. Alergia látex-fruta Latex-fruit allergy

    Directory of Open Access Journals (Sweden)

    Flávia Andréia MARIN

    2002-01-01

    Full Text Available O látex está sendo considerado o alergênico do ano 2000, tendo em vista que inúmeros indivíduos, principalmente profissionais da área de saúde e pacientes submetidos a várias intervenções diagnósticas e terapêuticas, estão freqüentemente expostos aos alérgenos do látex, presentes em produtos de borracha natural. As manifestações clínicas conseqüentes às reações alérgicas de hipersensibilidade imediata vão desde rinite, urticária, conjuntivite, angioedema, asma, até anafilaxia. Estudos recentes estão demonstrando que pacientes alérgicos ao látex desenvolvem concomitantemente sensibilização a certos alimentos de origem vegetal, especialmente frutas como papaia, figo, banana, abacate, kiwi, pêssego, abacaxi, melão e castanha, acreditando-se numa provável ocorrência de reações cruzadas entre os alérgenos do látex e destas frutas. Faz-se, então, uma revisão sobre a alergia ao látex, em particular sobre os grupos de risco, incluindo a presença de reatividade cruzada entre o látex e as frutas.The latex is being considered the allergenic agent of the year 2000, taking into account that several individuals, mainly health care professionals, and patients who had undergone many diagnostic and therapeutic interventions, are frequently exposed to latex allergens, which are present in natural rubber latex products. The clinical manifestations, derived from allergic reactions of immediate hypersensitivity vary from since rhinitis, conjunctivitis, urticaria, angioedema, asthma, to anaphylaxis. Recent researches are demonstrating that patients allergic to latex develop concomitantly sensitization to certain vegetable foods, especially fruits like papaya, fig, banana, avocado, kiwi, peach, pineapple, melon and chestnut, and a probable occurrence of cross reaction between allergens of latex and of these fruits is believed. A review is made about latex allergy, in particular about risk groups, including the presence of

  8. Low-flow water-quality characterization of the Gore Creek watershed, upper Colorado River basin, Colorado, August 1996

    Science.gov (United States)

    Wynn, Kirby H.; Spahr, Norman E.

    1998-01-01

    The Upper Colorado River Basin (UCOL) is one of 59 National Water-Quality Assessment (NAWQA) study units designed to assess the status and trends of the Nation?s water quality (Leahy and others, 1990). The UCOL study unit began operation in 1994, and surface-water-quality data collection at a network of 14 sites began in October 1995 (Apodaca and others, 1996; Spahr and others, 1996). Gore Creek, which flows through Vail, Colorado, originates in pristine alpine headwaters and is designated a gold-medal trout fishery. The creek drains an area of about 102 square miles and is a tributary to the Eagle River. Gore Creek at the mouth near Minturn (site 13 in fig. 1) is one of the 14 sites in the UCOL network. This site was selected to evaluate water quality resulting from urban development and recreational land use. The Gore Creek watershed has undergone rapid land-use changes since the 1960?s as the Vail area shifted from traditional mountain ranchlands to a four-season resort community. Residential, recreational, commercial, and transportation development continues near Gore Creek and its tributaries to support the increasing permanent and tourist population of the area. Interstate 70 runs through the watershed from Vail Pass near site 14, along the eastern side of Black Gore Creek, and along the northern side of the main stem of Gore Creek to the mouth of the watershed (fig. 1). A major local concern is how increasing urbanization/recreation affects the water quality, gold-medal trout fishery, and aesthetic values of Gore Creek. An evaluation of the spatial characteristics of water quality in the watershed upstream from site 13 at the mouth of Gore Creek (fig. 1) can provide local water and land managers with information necessary to establish water policy and make land-use planning decisions to maintain or improve water quality. Historical data collected at the mouth of Gore Creek provide information about water quality resulting from land use, but a synoptic

  9. Mutnovsky and Gorely Volcanoes, Kamchatka as Planetary Analogue Sites

    Science.gov (United States)

    Evdokimova, N.; Izbekov, P. E.; Krupskaya, V.; Muratov, A.

    2016-12-01

    Recent advances in Mars studies suggest that volcanic rocks, which dominated Martian surface in the past, have been exposed to alteration processes in a water-bearing environment during Noachian, before 3.7 Gy. Active volcanoes on Earth are natural laboratories, where volcanic processes and their associated products can be studied directly. This is particularly important for studying of alteration of juvenile volcanic products in aqueous environment because of the transient nature of some of the alteration products, as well as the environment itself. Terrestrial analogues help us to better understand processes on Mars; they are particularly useful as a test sites for preparation to future Mars missions. In this presentation we describe planetary analogue sites at Mutnovsky and Gorely Volcanoes in Kamchatka, which might be helpful for comparative studies and preparation to future Mars missions. Mutnovsky and Gorely Volcanoes are located 75 km south of Petropavlovsk-Kamchatsky, in the southern part of the Kamchatka Peninsula, Russia. The modern volcanic landscape in the area was shaped in Holocene (recent 10,000 years) through intermittent eruption of magmas ranging in composition from basalts to dacites and rhyodacites, with basaltic andesite lavas dominating in the modern relief. Two localities could be of a particular interest: (1) Mutnovsky NW thermal field featuring processes of active hydrothermal alteration of lavas of basaltic andesite and (2) dry lake at the bottom of Gorely caldera featuring products of mechanical disintegration of basaltic andesite lavas by eolian processes with short seasonal sedimentation in aqueous environment.

  10. 75 FR 67105 - Granular Polytetrafluoroethylene Resin From Italy and Japan

    Science.gov (United States)

    2010-11-01

    ... Polytetrafluoroethylene Resin From Italy and Japan AGENCY: United States International Trade Commission. ACTION... resin from Italy and Japan. SUMMARY: The Commission hereby gives notice that it has instituted reviews... revocation of the antidumping duty orders on granular polytetrafluoroethylene resin from Italy and Japan...

  11. Treatment of a Left Internal Mammary Artery to Pulmonary Artery Fistula with Polytetrafluoroethylene Covered Stents: A Case Report and Review of the Literature

    International Nuclear Information System (INIS)

    Abbott, J. Dawn; Brennan, Joseph J.; Remetz, Michael S.

    2004-01-01

    Internal mammary artery (IMA) to pulmonary artery (PA) fistula is a rare complication of coronary artery bypass grafting (CABG) that may present as myocardial ischemia. We describe a case of left IMA-to-PA fistula treated with balloon expandable coronary polytetrafluoroethylene (PTFE) graft stents and review previously reported cases of this entity

  12. 21 CFR 878.3500 - Polytetrafluoroethylene with carbon fibers composite implant material.

    Science.gov (United States)

    2010-04-01

    ... composite implant material. 878.3500 Section 878.3500 Food and Drugs FOOD AND DRUG ADMINISTRATION... Prosthetic Devices § 878.3500 Polytetrafluoroethylene with carbon fibers composite implant material. (a) Identification. A polytetrafluoroethylene with carbon fibers composite implant material is a porous device...

  13. VAC for external fixation of flail chest

    DEFF Research Database (Denmark)

    Winge, Rikke; Berg, Jais O; Albret, Rikke

    2012-01-01

    A large aterior chest wall defect following tumor resection was reconstructed with a Gore-Tex® membrane and a combined musculocutaneous rectus femoris and tensor fasciae latae free flap. Subsequent paradoxical respiration impeded weaning from the ventilator. Appliance of Vacuum Assisted Closure...

  14. The UNO Aviation Monograph Series: Aviation Security: An Annotated Bibliography of Responses to the Gore Commission

    Science.gov (United States)

    Carrico, John S.; Schaaf, Michaela M.

    1998-01-01

    This monograph is a companion to UNOAI Monograph 96-2, "The Image of Airport Security: An Annotated Bibliography," compiled in June 1996. The White House Commission on Aviation Safety and Security, headed by Vice President Al Gore, was formed as a result of the TWA Flight 800 crash in August 1996. The Commission's final report included 31 recommendations addressed toward aviation security. The recommendations were cause for security issues to be revisited in the media and by the aviation industry. These developments necessitated the need for an updated bibliography to review the resulting literature. Many of the articles were written in response to the recommendations made by the Gore Commission. "Aviation Security: An Annotated Bibliography of Responses to the Gore Commission" is the result of this need.

  15. TexMo: A Multi-language Development Environment

    DEFF Research Database (Denmark)

    Pfeiffer, Rolf-Helge; Wasowski, Andrzej

    2012-01-01

    Contemporary software systems contain a large number of artifacts expressed in multiple languages, ranging from domain-specific languages to general purpose languages. These artifacts are interrelated to form software systems. Existing development environments insufficiently support handling...... relations between artifacts in multiple languages. This paper presents a taxonomy for multi-language development environments, organized according to language representation, representation of relations between languages, and types of these relations. Additionally, we present TexMo, a prototype of a multi-language...... development environment, which uses an explicit relation model and implements visualization, static checking, navigation, and refactoring of cross-language relations. We evaluate TexMo by applying it to development of a web-application, JTrac, and provide preliminary evidence of its feasibility by running...

  16. source files for manuscript in tex format

    Data.gov (United States)

    U.S. Environmental Protection Agency — Source tex files used to create the manuscript including original figure files and raw data used in tables and inline text. This dataset is associated with the...

  17. 20 old and rare books from the library of Paul Gore

    Directory of Open Access Journals (Sweden)

    Liviu Papuc

    2014-12-01

    Full Text Available As is well known, most of the large library of Paul Gore, nearly 5,000 volumes, as evidenced by preserved inventory list, is currently kept in the “M. Eminescu” Central University Library in Iaşi. Based on dozens of specimens found in the storages and on the notes made by Paul Gore in the inventory-catalog, the paper presents their bibliographic description. It is made in the continuation of a communication that is to be printed in the Magazine of the Museum of the “Al.I. Cuza” University of Iaşi and in order to complete a full catalog of the library of the great scientist, the work on which was begun with great success by other researchers in the field.

  18. Topological Phase Diagrams of Bulk and Monolayer TiS2−xTex

    KAUST Repository

    Zhu, Zhiyong

    2013-02-12

    With the use of ab initio calculations, the topological phase diagrams of bulk and monolayer TiS2−xTex are established. Whereas bulk TiS2−xTex shows two strong topological phases [1;(000)] and [1;(001)] for 0.44Tex is a unique system for studying topological phases in three and two dimensions simultaneously.

  19. Topological Phase Diagrams of Bulk and Monolayer TiS2−xTex

    KAUST Repository

    Zhu, Zhiyong; Cheng, Yingchun; Schwingenschlö gl, Udo

    2013-01-01

    With the use of ab initio calculations, the topological phase diagrams of bulk and monolayer TiS2−xTex are established. Whereas bulk TiS2−xTex shows two strong topological phases [1;(000)] and [1;(001)] for 0.44Tex is a unique system for studying topological phases in three and two dimensions simultaneously.

  20. Structure and properties of polymer-silicate nanocomposites based on polytetrafluoroethylene

    Energy Technology Data Exchange (ETDEWEB)

    Sleptsova, Sardana A.; Okhlopkova, Aitalina A. [North-Eastern Federal University, Yakutsk (Russian Federation)

    2011-07-01

    The results of physicomechanical, tribological , and structural investigation of polytetrafluoroethylene based polymers and natural layered silicates are reported. It is shown that the tribological behaviour of the composites can be significantly improved by introducing a small amount of activated silicates. The results of structural examination of the composite friction surfaces by scanning-probe microscopy and IR spectroscopy are discussed. Key words: polytetrafluoroethylene, layered silicates, wear resistance, friction coefficient, structure, IR-spectrum.

  1. Uudised : Kitarrifestival Viljandis. Al Gore'i "Ebamugav tõde" ooperiks

    Index Scriptorium Estoniae

    2008-01-01

    23.-27. septembrini Viljandis toimuvast Eesti esimesest improvisatsioonilise kitarri festivalist. Milaano ooperiteatri La Scala esindajad andsid teada, et itaalia heliloojalt Giorgio Battistellilt on tellitud USA endise asepresidendi Al Gore'i keskkonnateemalisel Oscariga pärjatud filmil rajanev ooper (valmiva teosega on plaanis avada La Scala 2011. aasta hooaeg)

  2. Histologic and biomechanical evaluation of a novel macroporous polytetrafluoroethylene knit mesh compared to lightweight and heavyweight polypropylene mesh in a porcine model of ventral incisional hernia repair.

    Science.gov (United States)

    Melman, L; Jenkins, E D; Hamilton, N A; Bender, L C; Brodt, M D; Deeken, C R; Greco, S C; Frisella, M M; Matthews, B D

    2011-08-01

    To evaluate the biocompatibility of heavyweight polypropylene (HWPP), lightweight polypropylene (LWPP), and monofilament knit polytetrafluoroethylene (mkPTFE) mesh by comparing biomechanics and histologic response at 1, 3, and 5 months in a porcine model of incisional hernia repair. Bilateral full-thickness abdominal wall defects measuring 4 cm in length were created in 27 Yucatan minipigs. Twenty-one days after hernia creation, animals underwent bilateral preperitoneal ventral hernia repair with 8 × 10 cm pieces of mesh. Repairs were randomized to Bard(®)Mesh (HWPP, Bard/Davol, http://www.davol.com), ULTRAPRO(®) (LWPP, Ethicon, http://www.ethicon.com), and GORE(®)INFINIT Mesh (mkPTFE, Gore & Associates, http://www.gore.com). Nine animals were sacrificed at each timepoint (1, 3, and 5 months). At harvest, a 3 × 4 cm sample of mesh and incorporated tissue was taken from the center of the implant site and subjected to uniaxial tensile testing at a rate of 0.42 mm/s. The maximum force (N) and tensile strength (N/cm) were measured with a tensiometer, and stiffness (N/mm) was calculated from the slope of the force-versus-displacement curve. Adjacent sections of tissue were stained with hematoxylin and eosin (H&E) and analyzed for inflammation, fibrosis, and tissue ingrowth. Data are reported as mean ± SEM. Statistical significance (P 0.05 for all comparisons). However, for each mesh type, the maximum strength at 5 months was significantly lower than that at 1 month (P 0.05 for all comparisons). No significant differences with regard to inflammation, fibrosis, or tissue ingrowth were detected between mesh types at any time point (P > 0.09 for all comparisons). However, over time, inflammation decreased significantly for all mesh types (P 0.09). The maximum tensile strength of mesh in the abdominal wall decreased over time for HWPP, LWPP, and mkPTFE mesh materials alike. This trend may actually reflect inability to adequately grip specimens at later time points

  3. Radiation effect on polytetrafluoroethylene

    International Nuclear Information System (INIS)

    Deng Pengyang; Zhong Xiaoguang; Sun Jiazhen

    1999-01-01

    Polytetrafluoroethylene (PTFE) has always been regarded as a typical kind of radiation degradation polymer. But, in fact, PTFE can be induced crosslinking by γ-ray or electron beam at some special conditions (free oxygen and a narrow temperature region at 335 +- 5 degree C). Compared with radiation degradiation PTFE, cosslinking PTFE owns a lot of new properties. Some articles concerning with these have been published, which will be systematically reviewed in this

  4. Water recovery from flue gas

    Energy Technology Data Exchange (ETDEWEB)

    Heijboer, R.; Van Deelen-Bremer, M.H.; de Vos, F.; Zeijseink, A.G.L. [KEMA Nederland B.V. (Netherlands)

    2007-07-01

    In the power generation process a large amount of water is needed, for steam generation, flue gas cleaning etc. On the other hand a large amount of water is emitted to the atmosphere via the stack. For example a 400 MW coal fired power plant with a flue gas desulfurisation plant emits about 1,500,000 m{sup 3} per hour with a water concentration of about 11%. The emitted water has a rather good quality compared to surface water and needs less effort to be treated for use as make-up water. As the available amount of water in the flue gas from the earlier mentioned power plant is about 150 tons per hour, recovering 20% of this amount covers the make-up water needs of this 400 MW power plant. Direct condensation of the flue gas needs large cooling power and the condensed water is acidic and corrosive and needs cleanup treatment before it can be used in the water/steam cycle. KEMA developed a technology based on gas separation membranes which makes it possible to recover water from flue gas. The process is covered by a wide patent. The principle of the membrane is comparable to the material that is used in fabric like SympaTex{reg_sign} and GORE-TEX{reg_sign}. The GORE-TEX material is permeable to water vapor but rejects liquid water. The driving force is the water vapor pressure close to the human skin which is the higher than the water vapor pressure open the outside of the clothing. The selectivity of the GORE-TEX material however is not good enough to be used at the temperature of flue gas. The University of Twente (Netherlands) developed a membrane material based on modified PEEK which is highly selective of water vapor at flue gas temperatures. Based on the fact that flat membranes have an uneconomical surface to volume ratio, the choice has been made to use hollow fibre membranes. 6 figs.

  5. Comparative analysis of adherence, viability, proliferation and morphology of umbilical cord tissue-derived mesenchymal stem cells seeded on different titanium-coated expanded polytetrafluoroethylene scaffolds

    International Nuclear Information System (INIS)

    Hollweck, Trixi; Marschmann, Michaela; Hartmann, Isabel; Akra, Bassil; Meiser, Bruno; Reichart, Bruno; Eissner, Guenther; Eblenkamp, Markus; Wintermantel, Erich

    2010-01-01

    Umbilical cord tissue comprises an attractive new source for mesenchymal stem cells. Umbilical cord tissue-derived mesenchymal stem cells (UCMSC) exhibit self-renewal, multipotency and immunological naivity, and they can be obtained without medical intervention. The transfer of UCMSC to the ischemic region of the heart may have a favorable impact on tissue regeneration. Benefit from typical cell delivery by injection to the infarcted area is often limited due to poor cell retention and survival. Another route of administration is to use populated scaffolds implanted into the infarcted zone. In this paper, the seeding efficiency of UCMSC on uncoated and titanium-coated expanded polytetrafluoroethylene (ePTFE) scaffolds with different surface structures was determined. Dualmesh (registered) (DM) offers a corduroy-like surface in contrast to the comparatively planar surface of cardiovascular patch (CVP). The investigation of adherence, viability and proliferation of UCMSC demonstrates that titanium-coated scaffolds are superior to uncoated scaffolds, independent of the surface structure. Microscopic images reveal spherical UCMSC seeded on uncoated scaffolds. In contrast, UCMSC on titanium-coated scaffolds display their characteristic spindle-shaped morphology and a homogeneous coverage of CVP. In summary, titanium coating of clinically approved CVP enhances the retention of UCMSC and thus offers a potential cell delivery system for the repair of the damaged myocardium.

  6. Comparative analysis of adherence, viability, proliferation and morphology of umbilical cord tissue-derived mesenchymal stem cells seeded on different titanium-coated expanded polytetrafluoroethylene scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Hollweck, Trixi; Marschmann, Michaela; Hartmann, Isabel; Akra, Bassil; Meiser, Bruno; Reichart, Bruno; Eissner, Guenther [Department of Cardiac Surgery, University of Munich, Marchioninistrasse 15, 81377 Munich (Germany); Eblenkamp, Markus; Wintermantel, Erich, E-mail: Guenther.Eissner@med.uni-muenchen.d [Chair of Medical Engineering, Technische Universitaet Muenchen, Boltzmannstrasse 15, 85748 Garching (Germany)

    2010-12-15

    Umbilical cord tissue comprises an attractive new source for mesenchymal stem cells. Umbilical cord tissue-derived mesenchymal stem cells (UCMSC) exhibit self-renewal, multipotency and immunological naivity, and they can be obtained without medical intervention. The transfer of UCMSC to the ischemic region of the heart may have a favorable impact on tissue regeneration. Benefit from typical cell delivery by injection to the infarcted area is often limited due to poor cell retention and survival. Another route of administration is to use populated scaffolds implanted into the infarcted zone. In this paper, the seeding efficiency of UCMSC on uncoated and titanium-coated expanded polytetrafluoroethylene (ePTFE) scaffolds with different surface structures was determined. Dualmesh (registered) (DM) offers a corduroy-like surface in contrast to the comparatively planar surface of cardiovascular patch (CVP). The investigation of adherence, viability and proliferation of UCMSC demonstrates that titanium-coated scaffolds are superior to uncoated scaffolds, independent of the surface structure. Microscopic images reveal spherical UCMSC seeded on uncoated scaffolds. In contrast, UCMSC on titanium-coated scaffolds display their characteristic spindle-shaped morphology and a homogeneous coverage of CVP. In summary, titanium coating of clinically approved CVP enhances the retention of UCMSC and thus offers a potential cell delivery system for the repair of the damaged myocardium.

  7. Passing the English as a second language (ESL) supplemental texes exam keys to certification and language proficient learners

    CERN Document Server

    Wilmore, Elaine L

    2014-01-01

    Master the TExES with down-to-earth test prep strategies ESL certification is attainable if one understands the domains and competencies represented in the test and masters test prep skills. Dr. Elaine Wilmore, known for her popular TExES preparation seminars, synthesizes her knowledge and experiences and gives readers a practical approach to passing the ESL Supplemental Exam. Written in a conversational tone, the book uses real examples to help readers connect theory with actual practice and offers: Thorough discussions of relevant concepts related to domains and competencies Tables and graph

  8. HEALING OF MICROVENOUS PTFE PROSTHESES IMPLANTED INTO THE RAT FEMORAL VEIN

    NARCIS (Netherlands)

    VANDERLEI, B; DIJK, F; JONGEBLOED, WL; ROBINSON, PH; Bartels, H.

    44 PTFE prostheses (Gore-Tex(R); ID 1 mm) were implanted into rats' femoral veins by means of the sleeve anastomotic technique and were evaluated at regular intervals from 1 h up till 24 weeks after implantation by means of light and electron microscopy to study in detail their healing process. All

  9. Radiolysis of polytetrafluoroethylene

    International Nuclear Information System (INIS)

    Ferreira, Max Passos; Ferreira, Roberta Viana; Verly, Rodrigo Moreira

    2007-01-01

    Polytetrafluoroethylene is a linear polymer with structure: -[-CF 2 -CF 2 -] n -. Due to its singular properties, it is ideal for use at high temperatures and in chemically aggressive environments. It is extremely sensitive to ionizing radiation and is quickly degraded. PTFE radiolysis has been extensively studied. However, despite the many published papers, its degradation mechanism remains much uncertain. The degradation of polytetrafluoroethylene by γ irradiation yields perfluorinated carboxylic acids, olefin mixtures, and paraffins with different molecular weights. This process is a new alternative for the synthesis of aliphatic perfluorinated compounds used as intermediates for obtaining special products such as fluoro surfactants, electrical materials, special products for the textile industry, etc. PTFE scraps were irradiated with a uniform source of 60 Co gamma rays in oxygen atmosphere with a dose of 3 MGy. The radiolysis of PTFE yielded a water soluble material (probably fluorinated hydrocarbons with low molecular weight and main chains with 10-20 carbon atoms) and a water insoluble brittle polymeric material. Spectroscopy analysis in the infrared region of irradiated and non-irradiated PTFE were carried out. X-ray diffractometry pointed to changes in the crystalline structure of PTFE; scanning electron microscopy indicated alterations in samples irradiated under different conditions. Mass spectrometry was also used to identify the compounds formed after sample irradiation. Comparison of irradiated and non-irradiated FTIR spectra showed the formation of bands at 3450 cm -1 , associated with the O-H stretching, and at 1631 cm -1 , associated with the C=O stretching. The bands are characteristic of carboxylic acid, which indicates its formation in irradiated PTFE. (author)

  10. Overview of the Benzene and Other Toxics Exposure (BEE-TEX) Field Study.

    Science.gov (United States)

    Olaguer, Eduardo P

    2015-01-01

    The Benzene and other Toxics Exposure (BEE-TEX) field study was an experimental campaign designed to demonstrate novel methods for measuring ambient concentrations of hazardous air pollutants (HAPs) in real time and to attribute these concentrations to quantified releases from specific emission points in industrial facilities while operating outside facility fence lines. BEE-TEX was conducted in February 2015 at three neighboring communities in the Houston Ship Channel of Texas, where a large number of petrochemical facilities are concentrated. The novel technologies deployed during BEE-TEX included: (1) tomographic remote sensing based on differential optical absorption spectroscopy; (2) real-time broadcasting of ambient air monitoring data over the World Wide Web; (3) real-time source attribution and quantification of HAP emissions based on either tomographic or mobile measurement platforms; and (4) the use of cultured human lung cells in vitro as portable indicators of HAP exposure.

  11. Improvement of thermophysiological stress in participants wearing protective clothing for spraying pesticide, and its application in the field.

    Science.gov (United States)

    Hayashi, C; Tokura, H

    2000-04-01

    Thermoregulatory responses were compared under two experimental conditions, in the laboratory (Experiment I), and in the field (Experiment II), between two kinds of protective clothing for spraying pesticides. One was currently being used (Type A), and was composed of ready made Gore-Tex clothing, mask, polyurethane gloves and rubber boots. The other one was newly designed (Type B), and was composed of pesticide-proof clothing (100% cotton with water repellent finish), mask, Gore-Tex gloves, and special boots consisting of rubber for the feet and ankle and Gore-Tex around the legs. In addition, the head and chest were cooled by frozen gel strips fixed in the cap and undershirt. In Experiment I, five female adults took part, in a climate-chamber controlled at an ambient temperature of 28 degrees C and a relative humidity of 60%. In Experiment II, five farmers (one male and four female) were tested in an apple orchard in July, August and September. The main results are summarized as follows: (1) change of rectal temperature was inhibited more effectively in Type B in Experiment I, (2) change of heart rate tended to be lower in Type B than in Type A in both experiments, (3) salivary lactic acid concentration at the end of the first exercise was significantly higher in Type A than in Type B in Experiment I, (4) the number of contractions in the handgrip exercise which was performed immediately after the third exercise, was significantly smaller in Type A than in Type B in Experiment I, (5) subjective comfort sensation was significantly improved in Type B in Experiments I and II. Thus, it was concluded that the newly designed protective clothing could reduce thermal stress during the spraying of pesticides in an apple orchard in summer.

  12. Välis-Eesti meets tex-mex / Moonika Siimets

    Index Scriptorium Estoniae

    Siimets, Moonika, 1980-

    2012-01-01

    Portreelugu Torontos väliseesti perekonnas sündinud ja paljudes riikides elanud ning kokana töötanud Kristina Luppist, kes sattus Tallinnasse elama seoses Nõukogude Eesti toidukultuurist magistritööd kirjutades. Tex-Mex toiduretseptid s.h Margarita ja Guacamole

  13. Alergia ao látex e a frutas em profissionais da área da saúde

    Directory of Open Access Journals (Sweden)

    Marin Flávia Andréia

    2003-01-01

    Full Text Available INTRODUÇÃO: A alergia ao látex tornou-se um risco crescente aos indivíduos expostos, como os profissionais da área da saúde, tendo como agravo a associação com hipersensibilidade a vários alimentos, especialmente frutas. OBJETIVO: Avaliar a freqüência de sensibilização ao látex e a frutas em profissionais da área da saúde. MÉTODOS: Foram avaliados 53 profissionais da saúde, 81,9% do sexo feminino, aplicando-se questionário alergológico e testes cutâneos por puntura para alérgenos inaláveis, do látex e de frutas (mamão papaia, kiwi, abacate, banana, figo, tomate, noz. RESULTADOS: Dos 53 indivíduos estudados, 15 (28,5% eram alérgicos ao látex. A sensibilidade a frutas foi diagnosticada em 14 (26,4%, dos quais 10 (18,8% apresentavam teste por puntura positivo para o látex; as frutas alergênicas mais freqüentes foram papaia (80,0%, kiwi (60,0% e abacate (50,0%. CONCLUSÃO: Estes achados demonstram a existência da alergia látex-fruta, como descrito na literatura, sendo de suma importância uma avaliação in vivo em profissionais da área de saúde, caracterizados como potencial grupo de risco.

  14. Gore vidal's early Hollywood: history, fiction and film Gore vidal's early Hollywood: history, fiction and film

    Directory of Open Access Journals (Sweden)

    Thomas LaBorie Burns

    2008-04-01

    Full Text Available Although Gore Vidal has both worked as a Hollywood screenwriter and written criticism on Film—in this regard, he is perhaps best known for a sustained attack on the auteur theory of the magisterial director—I am concerned in this paper mainly with his fiction account of the early days of film-making in his novel Hollywood (1990 and the relation of film to national political life depicted therein. This novel is the sixth in a series that gives a more or less continuous historical picture of the social and political history of the US from colonial times to the present. “Political” for Vidal, however, means primarily the acts of statesmen, diplomats, and high-ranking military personnel, and the social history he presents is that of the upper-class which supplies their ranks, so that what Vidal is in fact offering in these six novels is what one might call the history of the American “movers-and-shakers”. Although Gore Vidal has both worked as a Hollywood screenwriter and written criticism on Film—in this regard, he is perhaps best known for a sustained attack on the auteur theory of the magisterial director—I am concerned in this paper mainly with his fiction account of the early days of film-making in his novel Hollywood (1990 and the relation of film to national political life depicted therein. This novel is the sixth in a series that gives a more or less continuous historical picture of the social and political history of the US from colonial times to the present. “Political” for Vidal, however, means primarily the acts of statesmen, diplomats, and high-ranking military personnel, and the social history he presents is that of the upper-class which supplies their ranks, so that what Vidal is in fact offering in these six novels is what one might call the history of the American “movers-and-shakers”.

  15. Deletion of the pluripotency-associated Tex19.1 gene causes activation of endogenous retroviruses and defective spermatogenesis in mice

    DEFF Research Database (Denmark)

    Ollinger, Rupert; Childs, Andrew J; Burgess, Hannah M

    2008-01-01

    . During male spermatogenesis, Tex19.1 expression is highest in mitotic spermatogonia and diminishes as these cells differentiate and progress through meiosis. In pluripotent stem cells, Tex19.1 expression is also downregulated upon differentiation. However, it is not clear whether Tex19.1 has an essential...... spermatogenesis. Immunostaining and histological analysis revealed defects in meiotic chromosome synapsis, the persistence of DNA double-strand breaks during meiosis, and a loss of post-meiotic germ cells in the testis. Furthermore, expression of a class of endogenous retroviruses is upregulated during meiosis...... in the Tex19.1(-/-) testes. Increased transposition of endogenous retroviruses in the germline of Tex19.1(-/-) mutant mice, and the concomitant increase in DNA damage, may be sufficient to disrupt the normal processes of recombination and chromosome synapsis during meiosis and cause defects...

  16. In vitro adherence of bacteria to prosthetic grafting materials

    International Nuclear Information System (INIS)

    Brewer, A.R.; Stromberg, B.V.

    1990-01-01

    Adherence of bacteria to prosthetic grafting material is thought to play an important role in the ultimate development of prosthetic infections. To evaluate the role of bacterial adherence in the initiation and colonization of prosthetic materials, Proplast II, Gore-Tex, and silicone were evaluated for adherence of Escherichia coli and Staphylococcus aureus. Bacteria were radiolabeled and incubated with the study material. Adherence was determined by scintillation. Adherence to Proplast II and Gore-Tex reached a maximum at approximately 45 minutes of incubation and demonstrated a detachment phenomenon with E. coli. Similar results were noted with S. aureus, but with a maximal attachment at approximately 30 minutes. Interestingly, bacterial attachment to silicone continued to increase throughout the time of the incubation. In addition, adherence of S. aureus was at a faster rate than E. coli. Attachment of bacteria is a multifactorial process. However, the PTFE graft demonstrates a slower rate of attachment, lower total number of attached bacteria, and faster detachment. The importance of this phenomenon may help explain the foreign body effect of increased susceptibility to infection of foreign materials

  17. An evaluation of the effectiveness of different techniques for intraoperative infiltration of antibiotics into alloplastic implants for use in facial reconstruction.

    Science.gov (United States)

    Keefe, Morgan S; Keefe, Michael A

    2009-01-01

    Reconstruction in the head and neck can be difficult owing to the size of the defect or characteristics of the tissue that needs to be replaced. Facial wounds or reconstruction sites can be subject to contamination, thereby risking infection of any implanted material even under ideal circumstances. Particular areas of concern are sites where minimizing the bacterial contamination prior to placing an implant is difficult (eg, the oral cavity and internal nose). Reconstruction involves the facial subcutaneous soft tissue and/or bone, and the ideal implant provides support and natural feel, as well as a low risk of infection. The biocompatibility of alloplastic implants depends on the tissue inertness of the implant and the porosity, allowing connective tissue ingrowth, which in turn decreases the susceptibility to infection. Scalafani et al demonstrated that alloplastic implants contaminated prior to fibrovascular ingrowth had a much higher incidence of infection and rejection. To examine the effectiveness of several techniques for infiltrating antibiotics into alloplastic implants of different porosity using 2 commonly used alloplastic implants, expanded polytetrafluoroethylene (e-PTFE, or GORE-TEX) and porous high-density polyethylene (Medpor). Using an in vitro bacterial growth inhibition model, we found that suction infiltration of the implant with antibiotics was the most effective technique, with a statistically significant advantage over other techniques used. The advantages of the suction impregnation were seen to be most effective using alloplasts with a smaller pore size (20-30 microm) (P < .001), but there was a statistically significant difference even with implants with a larger pore size (150-200 microm) (P < .001). Suction infiltration of antibiotics into porous implants seems to be the most effective method identified using an in vitro testing protocol. Further experiments will be needed to confirm the effectiveness in reducing the perioperative risk

  18. Radiation induced crosslinking of polytetrafluoroethylene

    International Nuclear Information System (INIS)

    Oshima, Akihiro; Tabata, Yoneho; Ikeda, Shigetoshi; Otsuhata, Kazushige; Kudoh, Hisaaki; Seguchi, Tadao.

    1995-01-01

    The Irradiation temperature effect on polytetrafluoroethylene (PTFE) from room temperature to 380degC was investigated by tensile test and thermal analysis. The behavior of tensile properties and changes of crystallinity on irradiation indicated the formation of a network structure in PTFE by radiation induced crosslinking in inert gas in the molten state just above the melting temperature of PTFE (327degC). The crosslinked PTFE showed a much improved radiation resistance in an atmospheric radiation field. (author)

  19. Salvage of bilateral renal artery occlusion after endovascular aneurysm repair with open splenorenal bypass

    Directory of Open Access Journals (Sweden)

    Samuel Jessula, MDCM

    2017-09-01

    Full Text Available We report renal salvage maneuvers after accidental bilateral renal artery coverage during endovascular aneurysm repair of an infrarenal abdominal aortic aneurysm. A 79-year-old man with an infrarenal abdominal aortic aneurysm was treated with endovascular aneurysm repair. Completion angiography demonstrated coverage of the renal arteries. Several revascularization techniques were attempted, including endograft repositioning and endovascular stenting through the femoral and brachial approach. The patient eventually underwent open splenorenal bypass with a Y Gore-Tex graft (W. L. Gore & Associates, Flagstaff, Ariz. After 3 months, computed tomography showed no evidence of endoleak and patent renal arteries. Renal function was well maintained, and the patient did not require dialysis.

  20. Polytetrafluoroethylene-jacketed stirrer modified with graphene oxide and polydopamine for the efficient extraction of polycyclic aromatic hydrocarbons.

    Science.gov (United States)

    Zhang, Zinxin; Mwadini, Mwadini Ahmada; Chen, Zilin

    2016-10-01

    Steel stirrers jacketed with polytetrafluoroethylene can be regarded as an ideal substrate for stirrer bar sorptive extraction. However, it is still a great challenge to immobilize graphene onto a polytetrafluoroethylene stirrer due to the high chemical resistance of the surface of a polytetrafluoroethylene stirrer. We describe here a method to modify the surface of polytetrafluoroethylene stirrers with graphene. In this work, graphene was used as the sorbent due to its excellent adsorption capability for aromatic compounds, such as polycyclic aromatic compounds. Graphene was successfully immobilized onto polytetrafluoroethylene-stirrer by a bio-inspired polydopamine functionalization method. The graphene-modified polytetrafluoroethylene-stirrer shows good stability and tolerance to stirring, ultrasonication, strong acidic and basic solutions, and to organic solvents. The multilayer coating was characterized by scanning electronic microscopy and Fourier transform infrared spectroscopy. After the optimization of some experimental conditions, the graphene-modified polytetrafluoroethylene stirrer was used for the stirrer bar sorptive extraction of polycyclic aromatic hydrocarbons, in which the binding between the polycyclic aromatic hydrocarbons and the graphene layer was mainly based on π-π stacking and hydrophobic interactions. The graphene-modified polytetrafluoroethylene-stirrer-based stirrer bar sorptive extraction and high-performance liquid chromatography method was developed for the determination of polycyclic aromatic hydrocarbons with great extraction efficiency, with enrichment factors from 18 to 62. The method has low limits of detection of 1-5 pg/mL, wide linear range (5-100 and 10-200 pg/mL), good linearity (R ≥ 0.9957) and good reproducibility (RSD ≤ 6.45%). The proposed method has been applied to determine polycyclic aromatic hydrocarbons in real dust samples. Good recoveries were obtained, ranging from 88.53 to 109.43%. © 2016 WILEY-VCH Verlag

  1. Early and long-term clinical and radiological follow-up results of expanded-polytetrafluoroethylene-covered stent-grafts for transjugular intrahepatic portosystemic shunt procedures

    International Nuclear Information System (INIS)

    Maleux, Geert; Heye, Sam; Thijs, Maria; Wilms, Guy; Nevens, Frederik; Verslype, Chris; Wilmer, Alexander

    2004-01-01

    The purpose of this study was to assess the therapeutic efficacy and immediate and long-term safety of expanded-tetrafluoroethylene covered stent-grafts for transjugular intrahepatic portosystemic shunts in patients with portal hypertension-related complications. A cohort of 56 patients suffering from severe portal hypertension-related complications underwent implantation of an expanded-polytetrafluoroethylene-covered stent-graft. All patients suffered from severe liver cirrhosis graded Child-Pugh A (n=8; 16%), B (n=13; 21%) or C (n=35; 63%). In 44 patients, the stent-graft was placed during the initial TIPS procedure (de novo TIPS); in the other 12 patients, the stent-graft was placed to repermeabilize the previously placed bare stent (TIPS revision). Follow-up was performed with clinical assessment, duplex ultrasound and, if abnormal or inconclusive, with invasive venography and pressure measurements. Per- en immediate post-procedural complications occurred in four patients (4/56, 7%). None of them was lethal. During follow-up, stent occlusion appeared in one patient and stenosis in two; no recurrence of bleeding was noted in all patients treated for variceal bleeding (n=28), and 24 of the 28 patients (86%) suffering from refractory ascites and/or hepatic hydrothorax were free of regular paracenteses and/or drainage of pleural effusion after shunt creation. The 30-day and global mortality for the total study population (n=56) was, respectively, 7% (n=4) and 28.5% (n=16). In the patient subgroup with variceal bleeding (n=28), 30-day mortality was 3.5% (n=1) and global mortality 14.2% (n=4). In the ascites and/or hydrothorax subgroup (n=28), 8.1% (n=3) mortality at 30 days was found and global mortality was 32.4% (n=12). In 10 patients of the 56 studied patients (18%), isolated hepatic encephalopathy occurred, which was lethal in 4 (Child C) patients (7%). Three of these four patients died within the 1st month after TIPS placement. A very high primary patency rate

  2. Early and long-term clinical and radiological follow-up results of expanded-polytetrafluoroethylene-covered stent-grafts for transjugular intrahepatic portosystemic shunt procedures

    Energy Technology Data Exchange (ETDEWEB)

    Maleux, Geert; Heye, Sam; Thijs, Maria; Wilms, Guy [University Hospitals Gasthuisberg, Department of Radiology, Leuven (Belgium); Nevens, Frederik; Verslype, Chris [University Hospitals Gasthuisberg, Department of Hepatology, Leuven (Belgium); Wilmer, Alexander [University Hospitals Gasthuisberg, Department of Medical Intensive Care Unit, Leuven (Belgium)

    2004-10-01

    The purpose of this study was to assess the therapeutic efficacy and immediate and long-term safety of expanded-tetrafluoroethylene covered stent-grafts for transjugular intrahepatic portosystemic shunts in patients with portal hypertension-related complications. A cohort of 56 patients suffering from severe portal hypertension-related complications underwent implantation of an expanded-polytetrafluoroethylene-covered stent-graft. All patients suffered from severe liver cirrhosis graded Child-Pugh A (n=8; 16%), B (n=13; 21%) or C (n=35; 63%). In 44 patients, the stent-graft was placed during the initial TIPS procedure (de novo TIPS); in the other 12 patients, the stent-graft was placed to repermeabilize the previously placed bare stent (TIPS revision). Follow-up was performed with clinical assessment, duplex ultrasound and, if abnormal or inconclusive, with invasive venography and pressure measurements. Per- en immediate post-procedural complications occurred in four patients (4/56, 7%). None of them was lethal. During follow-up, stent occlusion appeared in one patient and stenosis in two; no recurrence of bleeding was noted in all patients treated for variceal bleeding (n=28), and 24 of the 28 patients (86%) suffering from refractory ascites and/or hepatic hydrothorax were free of regular paracenteses and/or drainage of pleural effusion after shunt creation. The 30-day and global mortality for the total study population (n=56) was, respectively, 7% (n=4) and 28.5% (n=16). In the patient subgroup with variceal bleeding (n=28), 30-day mortality was 3.5% (n=1) and global mortality 14.2% (n=4). In the ascites and/or hydrothorax subgroup (n=28), 8.1% (n=3) mortality at 30 days was found and global mortality was 32.4% (n=12). In 10 patients of the 56 studied patients (18%), isolated hepatic encephalopathy occurred, which was lethal in 4 (Child C) patients (7%). Three of these four patients died within the 1st month after TIPS placement. A very high primary patency rate

  3. Cell microarrays on photochemically modified polytetrafluoroethylene

    Czech Academy of Sciences Publication Activity Database

    Mikulíková, R.; Moritz, S.; Gumpenberger, T.; Olbrich, M.; Romanin, C.; Bačáková, Lucie; Švorčík, V.; Heitz, J.

    2005-01-01

    Roč. 26, č. 27 (2005), s. 5572-5580 ISSN 0142-9612 R&D Projects: GA AV ČR(CZ) IAA5011301 Grant - others:CZ-AT(CZ) Scientific-Technical Cooperation 2004-9; Jubiläumsfonds der Österreichischen Nationalbank(AT) 10549 Institutional research plan: CEZ:AV0Z50110509 Keywords : polytetrafluoroethylene * surface modification * endothelial cells Subject RIV: EI - Biotechnology ; Bionics Impact factor: 4.698, year: 2005

  4. Third-Party Evaluation of Petro Tex Hydrocarbons, LLC, ReGen Lubricating Oil Re-refining Process

    Energy Technology Data Exchange (ETDEWEB)

    Compere, A L [ORNL; Griffith, William {Bill} L [ORNL

    2009-04-01

    This report presents an assessment of market, energy impact, and utility of the PetroTex Hydrocarbons, LLC., ReGen process for re-refining used lubricating oil to produce Group I, II, and III base oils, diesel fuel, and asphalt. PetroTex Hydrocarbons, LLC., has performed extensive pilot scale evaluations, computer simulations, and market studies of this process and is presently evaluating construction of a 23 million gallon per year industrial-scale plant. PetroTex has obtained a 30 acre site in the Texas Industries RailPark in Midlothian Texas. The environmental and civil engineering assessments of the site are completed, and the company has been granted a special use permit from the City of Midlothian and air emissions permits for the Texas Commission on Environmental Quality.

  5. Late Pleistocene temperature history of Southeast Africa: A TEX

    NARCIS (Netherlands)

    Woltering, M.; Johnson, T.C.; Werne, J.P.; Schouten, S.; Sinninghe Damsté, J.S.

    2011-01-01

    We present a TEX86-derived surface water temperature record for Lake Malawi that provides the first continuous continental record of temperature variability in the continental tropics spanning the past similar to 74 kyr with millennial-scale resolution. Average temperature during Marine Isotope

  6. Lipoplex gene transfer of inducible nitric oxide synthase inhibits the reactive intimal hyperplasia after expanded polytetrafluoroethylene bypass grafting.

    Science.gov (United States)

    Pfeiffer, Tomas; Wallich, Martina; Sandmann, Wilhelm; Schrader, Jürgen; Gödecke, Axel

    2006-05-01

    Intimal hyperplasia (IH) is most commonly the cause of graft occlusion in infrainguinal bypass grafting for arterial occlusive disease. We investigated the influence of nitric oxide on the IH of the arterial vessel wall at the region of prosthetic bypass anastomoses. Experiments were performed in 10 Foxhound dogs. We used a technique of inducible nitric oxide synthase (iNOS) overexpression by a non-virus-mediated, liposome-based iNOS gene transfer. The plasmid pSCMV-iNOS, which drives the expression of iNOS under control of the cytomegalovirus promoter, was complexed with cationic liposomes (lipoplexes). Segments of both carotid arteries were pretreated by intramural injection of a lipoplex solution by using an infiltrator balloon catheter (Infiltrator Drug Delivery Balloon System). In each dog, iNOS was administered at one side, and a control vector (pSCMV2) was administered at the contralateral side. Carotid arteries were ligated, and bypass grafts (expanded polytetrafluoroethylene, 6-mm, ring enforced) were implanted on both sides. The proximal and distal anastomoses (end-to-side fashion; running nonabsorbable sutures) were placed in the pretreated regions. After 6 months, the prostheses were excised, and the intimal thicknesses of 50 cross sections (orcein staining) of each anastomosis were measured planimetrically. The average reduction of the neointima thickness of the iNOS side in proximal anastomoses at the prosthetic wall, suture region, and arterial wall was 43%, 52%, and 81%, respectively. In distal anastomoses, the average reduction was 40%, 47%, and 52%, respectively. All differences of neointima thickness between the iNOS and control sides were statistically significant (Wilcoxon test; P < or = .05). Inducible NOS expression is an efficient approach for inhibition of IH. In contrast to earlier studies, which investigated the efficacy of gene therapeutic NOS expression at 3 to 4 weeks after intervention, the novelty of our findings is that a single

  7. Surgical Access to Jejunal Veins for Local Thrombolysis and Stent Placement in Portal Vein Thrombosis

    International Nuclear Information System (INIS)

    Schellhammer, Frank; Esch, Jan Schulte am; Hammerschlag, Sascha; Knoefel, Wolfram Trudo; Fuerst, Guenter

    2008-01-01

    Portal vein thrombosis is an infrequent entity, which may cause high morbidity and mortality. We report a case of portal vein thrombosis due to benign stenosis following partial pancreatoduodenectomy with segmental replacement of the portal vein by a Gore-tex graft. Using a surgical access to jenunal veins, local thrombolysis, mechanical fragmentation of thrombus, and stent placement were successfully performed.

  8. Management of malignant biliary obstruction: Technical and clinical results using an expanded polytetrafluoroethylene fluorinated ethylene propylene (ePTFE/FEP)-covered metallic stent after 6-year experience

    Energy Technology Data Exchange (ETDEWEB)

    Fanelli, Fabrizio; Orgera, Gianluigi; Bezzi, Mario; Rossi, Plinio; Allegritti, Massimiliano; Passariello, Roberto [University of Rome, Department of Radiological Sciences, Rome (Italy)

    2008-05-15

    To evaluate the efficacy and safety of an expanded polytetrafluoroethylene-fluorinated ethylene-propylene (ePTFE/FEP)-covered metallic stent in the management of malignant biliary obstruction. Eighty consecutive patients with malignant common bile duct strictures were treated by placement of 83 covered metallic stents. The stent-graft consists of an inner ePTFE/FEP lining and an outer supporting structure of nitinol wire. Clinical evaluation, assessment of serum bilirubin and liver enzyme levels were analyzed before biliary drainage, before stent-graft placement and during the follow-up period at 1, 3, 6, 9 and 12 months. Technical success was obtained in all cases. After a mean follow-up of 6.9{+-}4.63 months, the 30-day mortality rate was 14.2%. Survival rates were 40% and 20.2% at 6 and 12 months, respectively. Stent-graft patency rates were 95.5%, 92.6% and 85.7% at 3, 6 and 12 months, respectively. Complications occurred in five patients (6.4%); among these, acute cholecystitis was observed in three patients (3.8%). A stent-graft occlusion rate of 9% was observed. The percentage of patients undergoing lifetime palliation (91%) and the midterm patency rate suggest that placement of this ePTFE/FEP-covered stent-graft is safe and highly effective in achieving biliary drainage in patients with malignant strictures of the common bile duct. (orig.)

  9. Putting it to the test : alternative exploration techniques seek recognition

    Energy Technology Data Exchange (ETDEWEB)

    Cope, G.

    2005-06-01

    In the past, remote sensing techniques such as magnetic surveying, geochemical sampling and radiometric surveys, were efficient in hard rock mining exploration but were limited in hydrocarbon detection due to problems such as diurnal and weather variations. This article discussed some of the recent advances in technology that have been developed to overcome many of the drawbacks of older systems. Two Calgary-based companies are currently offering innovative and viable exploration alternatives. The Gore-Sorber module is the most accurate and comprehensive surface geochemical sampling technology currently available to the oil and gas industry. The testing module consists of 2 portions of expanded polytetrafluoroethylene polymer material sealed into a GORE-TEX sheath to prevent water and particle contamination. The module is then inserted into a shallow hole to a depth of 50 centimetres and left there for up to 2 weeks. The sample position is marked and surveyed. Over the course of the 2 weeks, volatile and semi-volatile soil gases in the C2-C15 range are absorbed into the material. The modules are analysed in mass spectrometers and gas chromatographs to determine zone and phase information. Advantages of the system include a reduction in soil contamination; the elimination of day-to-day fluctuations; and the fact that lab analysis allows for higher sensitivity. Costs are approximately $60,000 to $70,000 for an area of 16 square kilometres. Disadvantages include the inability to define the amount of hydrocarbons in place or their depth and the fact that proper field operation and collection of data by trained personnel is critical to the analysis process. The technique has been gaining in popularity in Canada as more exploration is directed towards environmentally sensitive frontier areas. Radiometric surveys record the gamma ray emissions of potassium, uranium and thorium as they decay radioactively. As hydrocarbons leak to the surface, they cause geochemical changes

  10. 77 FR 35959 - Atlas Pipeline Mid-Continent WestTex, LLC; Pioneer Natural Resources USA, Inc.; Notice of...

    Science.gov (United States)

    2012-06-15

    ... Mid-Continent WestTex, LLC; Pioneer Natural Resources USA, Inc.; Notice of Application Take notice that on May 30, 2012, Atlas Pipeline Mid-Continent WestTex, LLC (Atlas) and Pioneer Natural Resources... President and General Counsel, Atlas Pipeline Mid-Continent, LLC, 110 W. 7th Street, Suite 2300, Tulsa, OK...

  11. Experimental study of commercial size proton exchange membrane fuel cell performance

    International Nuclear Information System (INIS)

    Yan, Wei-Mon; Wang, Xiao-Dong; Lee, Duu-Jong; Zhang, Xin-Xin; Guo, Yi-Fan; Su, Ay

    2011-01-01

    Commercial sized (16 x 16 cm 2 active surface area) proton exchange membrane (PEM) fuel cells with serpentine flow chambers are fabricated. The GORE-TEX (registered) PRIMEA 5621 was used with a 35-μm-thick PEM with an anode catalyst layer with 0.45 mg cm -2 Pt and cathode catalyst layer with 0.6 mg cm -2 Pt and Ru or GORE-TEX (registered) PRIMEA 57 was used with an 18-μm-thick PEM with an anode catalyst layer at 0.2 mg cm -2 Pt and cathode catalyst layer at 0.4 mg cm -2 of Pt and Ru. At the specified cell and humidification temperatures, the thin PRIMEA 57 membrane yields better cell performance than the thick PRIMEA 5621 membrane, since hydration of the former is more easily maintained with the limited amount of produced water. Sufficient humidification at both the cathode and anode sides is essential to achieve high cell performance with a thick membrane, like the PRIMEA 5621. The optimal cell temperature to produce the best cell performance with PRIMEA 5621 is close to the humidification temperature. For PRIMEA 57, however, optimal cell temperature exceeds the humidification temperature.

  12. Nobeli rahupreemia favoriidiks püütakse suruda Al Goreþi / Kaivo Kopli

    Index Scriptorium Estoniae

    Kopli, Kaivo

    2007-01-01

    USA endise asepresidendi Al Goreþi valimise nimel järgmiseks Nobeli rahupreemia laureaadiks tehakse aktiivset lobitööd. Norra Nobeli instituudi direktori Geir Lundestadi hinnangul võib lobitöö anda aga hoopis tagasilöögi. Internetis väljapakutud kandidaatidest

  13. Surface Modification of Poly(tetrafluoroethylene) by Magnesium Amalgam

    Czech Academy of Sciences Publication Activity Database

    Kavan, Ladislav; Janda, Pavel; Weber, Jan

    2001-01-01

    Roč. 36, - (2001), s. 879-885 ISSN 0022-2461 R&D Projects: GA ČR GA203/98/1168; GA ČR GA203/98/1181 Institutional research plan: CEZ:AV0Z4040901 Keywords : poly(tetrafluoroethylene) * surface modification * ESCA Subject RIV: CG - Electrochemistry Impact factor: 0.728, year: 2001

  14. Kliimateadlastele ja Al Gore'ile läinud Nobel oli oodatud otsus / Liisi Poll, Oliver Tiks

    Index Scriptorium Estoniae

    Poll, Liisi, 1980-

    2007-01-01

    Nobeli preemiat välja andev komitee Oslos otsustas anda Nobeli rahupreemia rahvusvahelisele kliimamuutuste töörühmale ja USA endisele asepresidendile Al Gore'ile. Lisa: Tänavune Nobeli rahupreemia

  15. Mechanisms of Contact Electrification at Aluminum-Polytetrafluoroethylene and Polypropylene-Water

    KAUST Repository

    Nauruzbayeva, Jamilya

    2017-01-01

    of electrons, but a comprehensive understanding of contact electrification at interfaces of electrical insulators, such as air, water, polytetrafluoroethylene (PTFE), polypropylene remains incomplete. In fact, a variety of mechanisms responsible for transfer

  16. Management of horn gore injury and urticaria in a dairy cow: A case report

    Directory of Open Access Journals (Sweden)

    Abdul Nasir Tijjani

    2015-09-01

    Full Text Available This paper reports how a 4-year old Friesien-Sahiwal cross cow weighing 380 kg with horn gore injury on the left labia of the vulva was managed at the Large Animal Clinic, University Putra Malaysia. The lacerated wound measuring about 4-cm long was originated as a result of horn goring from another cow two weeks prior presentation of the cow to the clinic. Physical examination of the cow incidentally revealed urticaria on the left ventro-lateral aspect of the neck suspected to be sequel of hypersensitivity. The wound was treated by topical application of a mixture of Iodine, Benacillin LA, Biomectin 1% and Ilium Dermapred made into cream. While the uticaria was treated by intramuscular injection of Chlorpheniramine maleate at 0.5 mg/kg bwt. Animal management, housing design and presence of sharp horns are some of the factors that can lead to physical traumatic injuries in dairy cows. [J Adv Vet Anim Res 2015; 2(3.000: 366-368

  17. Bradley vs. Gore: how media covered proposals for health insurance reform in the context of the 2000 presidential campaign.

    Science.gov (United States)

    Mebane, Felicia

    2003-01-01

    This study examines how often national media reported key aspects of Senator Bill Bradley's and Vice President Al Gore's proposals for health insurance reform during the 2000 Democratic primary campaign. The results show that news media reported on Bradley's plan and major features of his plan significantly more often than Gore's. Additionally, few reports contained explicit comparisons that explained which plan would have covered more people or cost more. Public health and media professionals need to work together to improve the quality of information the public depends on to develop views about and support for the uninsured.

  18. Biomechanical comparison of expanded polytetrafluoroethylene (ePTFE) and PTFE interpositional patches and direct tendon-to-bone repair for massive rotator cuff tears in an ovine model.

    Science.gov (United States)

    McKeown, Andrew Dj; Beattie, Rebekah F; Murrell, George Ac; Lam, Patrick H

    2016-01-01

    Massive irreparable rotator cuff tears are a difficult problem. Modalities such as irrigation and debridement, partial repair, tendon transfer and grafts have been utilized with high failure rates and mixed results. Synthetic interpositional patch repairs are a novel and increasingly used approach. The present study aimed to examine the biomechanical properties of common synthetic materials for interpositional repairs in contrast to native tendon. Six ovine tendons, six polytetrafluoroethylene (PTFE) felt sections and six expanded PTFE (ePTFE) patch sections were pulled-to-failure to analyze their biomechanical and material properties. Six direct tendon-to-bone surgical method repairs, six interpositional PTFE felt patch repairs and six interpositional ePTFE patch repairs were also constructed in ovine shoulders and pulled-to-failure to examine the biomechanical properties of each repair construct. Ovine tendon had higher load-to-failure (591 N) and had greater stiffness (108 N/mm) than either PTFE felt (296 N, 28 N/mm) or ePTFE patch sections (323 N, 34 N/mm). Both PTFE felt and ePTFE repair techniques required greater load-to-failure (225 N and 177 N, respectively) than direct tendon-to-bone surgical repairs (147 N) in ovine models. Synthetic materials lacked several biomechanical properties, including strength and stiffness, compared to ovine tendon. Interpositional surgical repair models with these materials were significantly stronger than direct tendon-to-bone model repairs.

  19. TEX86 paleothermometry : proxy validation and application in marine sediments

    NARCIS (Netherlands)

    Huguet, C.

    2007-01-01

    Determination of past sea surface temperature (SST) is of primary importance for the reconstruction of natural climatic changes, modelling of climate and reconstruction of ocean circulation. Recently, a new SST proxy was introduced, the TetraEther indeX of lipids with 86 carbons (TEX86), which is

  20. Improvement of Polytetrafluoroethylene Surface Energy by Repetitive Pulse Non-Thermal Plasma Treatment in Atmospheric Air

    International Nuclear Information System (INIS)

    Yang Guoqing; Zhang Guanjun; Zhang Wenyuan

    2011-01-01

    Improvement of polytetrafluoroethylene surface energy by non-thermal plasma treatment is presented, using a nanosecond-positive-edge repetitive pulsed dielectric barrier discharge generator in atmospheric air. The electrical parameters including discharging power, peak and density of micro-discharge current were calculated, and the electron energy was estimated. Surface treatment experiments of polytetrafluoroethylene films were conducted for both different applied voltages and different treating durations. Results show that the surface energy of polytetrafluoroethylene film could be improved to 40 mJ/m 2 or more by plasma treatment. Surface roughness measurement and surface X-ray photoelectron spectroscopy analysis indicate that there are chemical etching and implantation of polar oxygen groups in the sample surface treating process, resulting in the improvement of the sample surface energy. Compared with an AC source of 50 Hz, the dielectric barrier discharges generated by a repetitive pulsed source could provide higher peak power, lower mean power, larger micro-discharge current density and higher electron energy. Therefore, with the same applied peak voltage and treating duration, the improvement of polytetrafluoroethylene surface energy using repetitive pulsed plasma is more effective, and the plasma treatment process based on repetitive pulsed dielectric barrier discharges in air is thus feasible and applicable.

  1. Structural changes in polytetrafluoroethylene molecular chains upon sliding against steel

    NARCIS (Netherlands)

    Shen, J.T.; Pei, Y.T.; Hosson, J.Th.M. De

    In this work, the influence of dry sliding between a steel counterpart ball and polytetrafluoroethylene (PTFE) plate sample on the transformation of PTFE molecular structure is investigated. With X-ray diffraction, differential scanning calorimetry, Fourier transform infrared (FT-IR) spectroscopy

  2. Influence of gamma-radiation on tensile strength properties of polytetrafluoroethylene (PTFE)

    CERN Document Server

    Gafurov, U G; Nemkova, N

    2002-01-01

    The tensile strength properties of polytetrafluoroethylene are studied at modification doses of gamma-irradiation. The main molecular process of polymer destruction is found to be the thermostimulated slippage of molecular chains. (author)

  3. TRATAMIENTOS PARA REDUCIR LOS DAÑOS POR LÁTEX EN MANGO (Mangifera indica

    Directory of Open Access Journals (Sweden)

    Marta Montero

    2005-01-01

    Full Text Available El objetivo de este estudio fue evaluar tratamientos alternativos para reducir las manchas de látex en mango. Se utilizaron frutos del cultivar Amarilla y soluciones (1% en agua de eter lauril sulfonato de sodio (ELSS, ácido sulfónico (AS, amida de coco (AC y nonil fenol etoxilado (NFE; hipoclorito de sodio (100 y 200 mg l-1 en agua; agua; con 3 tratamientos testigo (deslechado en seco y manchado intencional con limpieza posterior y sin ella. Se midió la incidencia y severidad de las manchas sobre la cáscara y en las lenticelas. Los residuos de látex y las manchas sobre la cáscara generalmente cubrieron menos de 5% del área total; sin embargo, cuando los frutos se deslecharon en agua, en las soluciones con los tensoactivos,o al mancharlos intencionalmente, las manchas fueron severas. Los tensoactivos AS, AC y NFE provocaron oscurecimiento de las lenticelas en el 60-100% de la superficie, con grado de severidad alto (3,8-4,0, sin estar asociados a residuos de látex sobre la cáscara. La severidad de la mancha de látex resultó leve cuando la fruta se deslechó en seco (0,8 y fue moderada cuando se hizo en agua y en las soluciones de cloro con 100 y 200 mg l-1 (1,7, 1,6 y 1,3, respectivamente. El trata- miento posterior con fungicida y agua caliente hizo más visibles las manchas. Los 3 mejores tratamientos fueron el deslechado en ELSS al 1%, en la solución de hipoclorito de sodio (100 mg l-1 y en seco.

  4. Influence of deep-water derived isoprenoid tetraether lipids on the TEX

    NARCIS (Netherlands)

    Kim, J.H.; Schouten, S.; Rodrigo-Gámiz, M.; Rampen, S.W.; Marino, G.; Huguet, C.; Helmke, P.; Buscail, R.; Hopmans, E.C.; Pross, J.; Sangiorgi, F.; Middelburg, J.; Sinninghe Damsté, J.S.

    2015-01-01

    The View the MathML sourceTEX86H paleothermometer based on isoprenoid glycerol dialkyl glycerol tetraethers (isoGDGTs) has widely been applied in various marine settings to reconstruct past sea surface temperatures (SSTs). However, it still remains uncertain how well this proxy reconstructs annual

  5. ShapeTex : Implementing shape-changing structures in fabric for wearable actuation

    NARCIS (Netherlands)

    Du, Jiachun; Markopoulos, Panos; Wang, Qi; Toeters, Marina; Gong, Ting

    2018-01-01

    Research in smart textiles and garments has mostly focused on integrating sensing technology. In order to make garments that are truly interactive it is also essential to develop technologies for actuating smart garments and textiles. This paper introduces ShapeTex, a thermal shape changing fabric

  6. The noncovalent bonding of antibiotics to a polytetrafluoroethylene-benzalkonium graft

    International Nuclear Information System (INIS)

    Harvey, R.A.; Greco, R.S.

    1981-01-01

    This study evaluates the noncovalent bonding of anionic antibiotics to polytetrafluoroethylene grafts using benzalkonium chloride as a cationic anchor. The binding of radiolabeled surfactants and antibiotics was evaluated by liquid scintillation and in an in vitro microbiologic assay against Staphylococcus aureus. Significant quantities of antibiotic were bound when the grafts were pretreated with benzalkonium in ethanol or aqueous solution at elevated temperature. Bound antibiotic is stable in aqueous salt solutions, but slowly dissociates in the presence of blood or serum. The ionic nature of the bonding process is clarified by the use of a variety of antibiotics and surfactants with complementary charges. The ability of the benzalkonium treated grafts to adsorb antibiotic from blood is, likewise, demonstrated and the possibility of concomitantly binding heparin and antibiotic simultaneously is evaluated. These studies support the ability to noncovalently bond antibiotics to polytetrafluoroethylene surfaces and form the basis of eventually utilizing these surfaces in the prevention of vascular prosthetic infections

  7. Long-Term Outcomes of Double-Layered Polytetrafluoroethylene Membrane-Covered Self-Expandable Segmental Metallic Stents (Uventa) in Patients with Chronic Ureteral Obstructions: Is It Really Safe?

    Science.gov (United States)

    Kim, Myong; Hong, Bumsik; Park, Hyung Keun

    2016-12-01

    To evaluate the long-term clinical efficacy and safety of double-layered polytetrafluoroethylene membrane-covered self-expandable segmental metallic stents (Uventa) in patients with chronic ureteral obstruction. In a retrospective study, a total of 50 ureter units (44 patients) with chronic obstructions were included from July 2010 to May 2015. Indications for Uventa placement were primary stenting for malignant ureteral obstruction, failed conventional polymeric Double-J stent (PS), or percutaneous nephrostomy (PCN) technique, with comorbidities or fears limiting PS/PCN changes, or with irritation or pain due to PS/PCN. Patients underwent Uventa stent placement using the antegrade or retrograde approach. There were no immediate procedure-related complications, and all stents were placed in the proper sites. During the median follow-up of 30.9 (interquartile range [IQR], 8.1-49.0) months, the primary (no obstruction and no additional intervention) and overall success (no obstruction and no additional intervention except supplementary Uventa) was 30.0% and 34.0%, respectively. Moreover, 14 of 50 ureter units (28.0%) experienced major complications (≥Clavien-Dindo class IIIb), such as ureteroarterial fistula (three cases, 6.0%), ureteroenteric fistula (three, 6.0%), ureterovaginal fistula (one, 2.0%), ureter perforation (one, 2.0%), uncontrollable bleeding (one, 2.0%), and complete obstruction (five, 10.0%). On univariate analysis, major complications were associated with female (odds ratio [OR] = 6.000), cervical cancer (OR = 4.667), ureteral stricture length (≥6.0 cm, OR = 4.583), and placement duration (≥24.0 months, OR = 20.429; all p stent demonstrated poor treatment outcomes with frequent major complications in patients with chronic ureteral obstructions.

  8. Climate Change Draws World Attention: The 2007 Nobel Peace Award Goes to Gore and IPCC

    Science.gov (United States)

    Bisland, Beverly Milner; Ahmad, Iftikhar

    2008-01-01

    In the fall of 2007, the Nobel Committee awarded their Peace Prize to the Intergovernmental Panel on Climate Change (a scientific intergovernmental body set up by the World Meteorological Organization and by the United Nations Environment Program) and to former Vice-President Al Gore, Jr. The committee praised the United Nations panel for creating…

  9. Marine crenarchaeotal membrane lipids in decapods: Implications for the TEX86 paleothermometer

    NARCIS (Netherlands)

    Huguet, C.; Cartes, J.E.; Sinninghe Damsté, J.S.; Schouten, S.

    2006-01-01

    Pelagic Crenarchaeota produce glycerol dibiphytanyl glycerol tetraethers (GDGTs) as membrane lipids, and the GDGT composition changes according to growth temperature. This forms the basis of the TEX86 paleotemperature proxy. This ratio correlates with sea surface temperature (SST) despite the fact

  10. The Impact of TexAQS 2000 on Air Quality Planning in Houston

    Science.gov (United States)

    Thomas, J. W.; Price, J. H.

    2002-12-01

    Before the Texas 2000 Air Quality Study (TexAQS 2000) the State used the Urban Airshed Model to model nine different episodes in Houston with very poor results: only one episode met EPA model performance criteria. Questions existed regarding emissions uncertainties, meteorological modeling, and model chemistry. NOAA, DOE, and SOS led more than 35 organizations and 250 investigators who participated in TexAQS 2000. Major findings from TexAQS 2000 are: 1. There are two types of meteorological patterns that lead to ozone episodes in the Houston area: (i) stagnation associated with the sea breeze flow reversal causes a pool of industrial emissions and ozone to accumulate, then to move across the city as the wind flow picks up and (ii) plumes of ozone form when relatively persistent winds carry the emissions away from the city and industrial areas. 2. The chemistry that produces high ozone concentrations and rapid rises in ozone in the Houston area has been explained: multiple investigators in TexAQS 2000 have documented more rapid and more efficient formation of ozone in the plume from the Houston industrial area than any of them has observed in any previous field study. Houston's exceptionally rapid ozone formation arises from large amounts of anthropogenic VOCs in the atmosphere, often from the same plants that provide sufficient NOx. 3. This rapid and efficient ozone formation results most often from the presence of a specific subclass of hydrocarbons called light olefins, primarily ethylene and propylene. 4. Sometimes it is other specific hydrocarbons that cause the rapid formation of high concentrations of ozone, and sometimes it is just the total mass of a lot of relatively unreactive hydrocarbons. 5. The current emissions inventory for ethylene and propylene, as well as other VOCs, underestimates their routine emissions by a factor of roughly five to ten or perhaps even more. 6. It is not clear whether the emissions causing Houston's rapid ozone formation are

  11. Efecto in vitro del látex de Ficus insipida sobre la cascada de la coagulación sanguínea.

    Directory of Open Access Journals (Sweden)

    Fernando Concha-Benavente

    2010-07-01

    Full Text Available Es necesario investigar drogas naturales nuevas que aporten principios farmacológicos activos para ser utilizadas como una alternativa terapéutica. Por este motivo nos propusimos estudiar a Ficus insipida, cuyo látex ha sido usado como antihelmíntico durante muchos años en la amazonía, pero se investigó solo superficialmente su efecto anticoagulante in vitro. Objetivo: Comprobar el efecto anticoagulante in vitro y determinar la vía de la coagulación sobre la que actúa el látex de Ficus insípida. Material y métodos: Se obtuvo el látex de Ficus insipida y se prepararon diferentes concentraciones del mismo. Se obtuvieron muestras de sangre venosa periférica de 5 donantes voluntarios, anticoagulándolas con citrato de sodio. Luego, éstas se mezclaron con las diluciones del látex, se centrifugaron y se extrajo el plasma. Posteriormente, se obtuvo un pool de plasma para cada concentración del látex y se procedió a determinar el Tiempo de Protrombina (TP y el Tiempo de Tromboplastina Parcial activada (TTPa, respectivamente. Resultados: Se encontró que el látex de Ficus insipida prolongó el TP a una concentración mayor o igual a 0,03125% (V/V, y ambos, el TP y TTPa a una concentración mayor o igual a 0,15% (V/V. Conclusiones: Los resultados obtenidos nos permiten afirmar que el látex de Ficus insipida posee un efecto anticoagulante in vitro dosis dependiente sobre la vía extrínseca de la coagulación sanguínea a una concentración igual o mayor a 0,03125% (V/V y que a una concentración igual o mayor a 0,15% (V/V posee un potente efecto anticoagulante sobre ambas vías de la coagulación.(Rev Med Hered 2010;21:146-152.

  12. Reações de alergia provocadas pelo látex: um alerta aos trabalhadores da área da saúde

    Directory of Open Access Journals (Sweden)

    Rosimeire Aparecida Mendes Lopes

    1999-09-01

    Full Text Available É apresentado um levantamento bibliográfico de artigos referentes às reações de alergia ao látex, publicados nos últimos anos. O primeiro artigo sobre reação de alergia associado ao uso do látex foi publicado em 1979, na Grã-Bretanha, e desde então, de forma crescente, outros casos têm sido relatados(Barion, 1993. As reações do Tipo I (reação imediata e Tipo IV (resposta tardia estão envolvidas nos processos de alergia ao látex (Steelman, 1995. Uma das explicações para a alergia por contato é o processo inadequado de lavagem durante a manufatura, com retenção de proteínas hidrossolúveis que causam reação alérgica em pessoas susceptíveis. Na literatura são descritos casos de reações que variam de dermatite de contato à choque anafilático. Conclui-se que os achados evidenciam a necessidade da equipe de saúde ter conhecimento das implicações prováveis da alergia ao látex.

  13. Anatomic factors associated with acute endograft collapse after Gore TAG treatment of thoracic aortic dissection or traumatic rupture.

    NARCIS (Netherlands)

    Muhs, B.E.; Balm, R.; White, G.H.; Verhagen, H.J.M.

    2007-01-01

    OBJECTIVE: The potentially devastating complication of total or near total thoracic endoprosthesis collapse has been described with the TAG device (W. L. Gore & Associates, Flagstaff, Ariz). This rare complication has resulted in a warning to clinicians and speculation about the etiology of this

  14. Anatomic factors associated with acute endograft collapse after Gore TAG treatment of thoracic aortic dissection or traumatic rupture

    NARCIS (Netherlands)

    Muhs, Bart E.; Balm, Ron; White, Geoffrey H.; Verhagen, Hence J. M.

    2007-01-01

    OBJECTIVE: The potentially devastating complication of total or near total thoracic endoprosthesis collapse has been described with the TAG device (W. L. Gore & Associates, Flagstaff, Ariz). This rare complication has resulted in a warning to clinicians and speculation about the etiology of this

  15. Scalable bonding of nanofibrous polytetrafluoroethylene (PTFE) membranes on microstructures

    Science.gov (United States)

    Mortazavi, Mehdi; Fazeli, Abdolreza; Moghaddam, Saeed

    2018-01-01

    Expanded polytetrafluoroethylene (ePTFE) nanofibrous membranes exhibit high porosity (80%-90%), high gas permeability, chemical inertness, and superhydrophobicity, which makes them a suitable choice in many demanding fields including industrial filtration, medical implants, bio-/nano- sensors/actuators and microanalysis (i.e. lab-on-a-chip). However, one of the major challenges that inhibit implementation of such membranes is their inability to bond to other materials due to their intrinsic low surface energy and chemical inertness. Prior attempts to improve adhesion of ePTFE membranes to other surfaces involved surface chemical treatments which have not been successful due to degradation of the mechanical integrity and the breakthrough pressure of the membrane. Here, we report a simple and scalable method of bonding ePTFE membranes to different surfaces via the introduction of an intermediate adhesive layer. While a variety of adhesives can be used with this technique, the highest bonding performance is obtained for adhesives that have moderate contact angles with the substrate and low contact angles with the membrane. A thin layer of an adhesive can be uniformly applied onto micro-patterned substrates with feature sizes down to 5 µm using a roll-coating process. Membrane-based microchannel and micropillar devices with burst pressures of up to 200 kPa have been successfully fabricated and tested. A thin layer of the membrane remains attached to the substrate after debonding, suggesting that mechanical interlocking through nanofiber engagement is the main mechanism of adhesion.

  16. Evaluating Production of Cyclopentyl Tetraethers by Marine Group II Euryarchaeota in the Pearl River Estuary and Coastal South China Sea: Potential Impact on the TEX86 Paleothermometer

    Directory of Open Access Journals (Sweden)

    Jin-Xiang Wang

    2017-10-01

    Full Text Available TEX86 [TetraEther indeX of glycerol dialkyl glycerol tetraethers (GDGTs with 86 carbon atoms] has been widely applied to reconstruct (paleo- sea surface temperature. Marine Group I (MG-I Thaumarchaeota were thought to be the primary source of GDGTs constituting the TEX86 formula; however, recent research has suggested that Marine Group II (MG-II Euryarchaeota may also contribute significantly to the GDGT pool in the ocean. Little is known regarding the potential impact of MG-II Euryarchaeota-derived GDGTs on TEX86 values recorded in marine sediments. In this study, we assessed the relationship between distributions of GDGTs and MG-II Euryarchaeota and evaluated its potential effect on the TEX86 proxy. Lipid and DNA analyses were performed on suspended particulate matter and surface sediments collected along a salinity gradient from the lower Pearl River (river water and its estuary (mixing water to the coastal South China Sea (SCS, seawater. TEX86-derived temperatures from the water column and surface sediments were significantly correlated and both were lower than satellite-based temperatures. The ring index (RI values in these environments were higher than predicted from the calculated TEX86-RI correlation, indicating that the GDGT pool in the water column of the PR estuary and coastal SCS comprises relatively more cyclopentane rings, which thereby altered TEX86 values. Furthermore, the abundance of MG-II Euryarchaeota 16S rRNA gene in the mixing water was two to three orders of magnitude higher than those observed in the river or seawater. Significant linear correlations were observed between the gene abundance ratio of MG-II Euryarchaeota to total archaea and the fractional abundance of GDGTs with cyclopentane rings. Collectively, these results suggest that MG-II Euryarchaeota likely produce a large proportion of GDGTs with 1–4 cyclopentane moieties, which may bias TEX86 values in the water column and sediments. As such, valid

  17. HiPer-tex{sup TM} WindStrand{sup TM}: A new generation of high performance reinforcement

    Energy Technology Data Exchange (ETDEWEB)

    Peters, L.; Adolphs, G. [Owens Corning S and T, Battice (Belgium); Bech, J.I.; Broendsted, P. [Risoe National Lab., Material Research Dept., Roskilde (Denmark)

    2006-07-01

    Owens Corning has recently introduced the HiPer-texTM family of high performance reinforcements of which WindStrandTM is engineered to specific customer process requirements of resin infusion and prepregs for Wind Turbine blades manufacture. The new HiPer-tex technology platform enables up to 35% higher strength, 17% higher modulus, better impact, corrosion and high temperature resistance and significantly better fatigue properties versus traditional E Glass laminates. These attributes have been measured with various laminates types and are presented in this paper. These better performances are needed in markets such as Wind Energy, pressure vessels, armour, aerospace and light weight structural component. (au)

  18. Translanguaging, TexMex, and Bilingual Pedagogy: Emergent Bilinguals Learning through the Vernacular

    Science.gov (United States)

    Sayer, Peter

    2013-01-01

    This article presents an ethnographic study of how bilingual teachers and children use their home language, TexMex, to mediate academic content and standard languages. From the premise that TESOL educators can benefit from a fuller understanding of students' linguistic repertoires, the study describes language practices in a second-grade classroom…

  19. Recognizing subtle evidence for silicic magma derivation from petrochemically-similar arc crust: Isotopic and chemical evidence for the bimodal volcanic series of Gorely Volcanic Center, Kamchatka, Russia

    Science.gov (United States)

    Seligman, A. N.; Bindeman, I. N.; Ellis, B. S.; Ponomareva, V.; Leonov, V.

    2012-12-01

    The Kamchatka Peninsula is home to some of the most prolific subduction related volcanic activity in the world. Gorely caldera and its central volcano are located in the rear of its currently active Eastern Volcanic Front. Recent work determined the presence of explosive ignimbrite eruptions sourced from Gorely volcano during the Pleistocene. We studied 32 eruptive units, including tephrochronologically-dated Holocene tephra, stratigraphically-arranged ignimbrites, as well as pre- and post-caldera lavas. We analyzed oxygen isotope ratios of pyroxene and plagioclase grains by laser fluorination, and major and trace element compositions of whole rocks. In addition, we determined 87Sr/86Sr and 143Nd/144Nd ratios of caldera-forming ignimbrite eruptions. Chemical compositions show that Gorely eruptive units range from basalt to basaltic andesite in the "Pra-Gorely" stages prior to caldera formation and the modern Gorely stages forming its current edifice. In contrast, eruptive material from earlier ignimbrites exposed at Opasny Ravine consists primarily of dacite. Whole rock analyses for Gorely indicate that silicic rocks and ignimbrites volumetrically dominate all other products, forming separate bimodal peaks in our SiO2-frequency diagram. In addition, trace element concentrations and ratios define two trends, one for more silicic and another for more mafic material. δ18Omelt values range from a low of 4.85 up to 6.22‰, where the lowest value was found in the last caldera forming eruption, suggesting incorporation of hydrothermally-altered material from earlier eruptions. 87Sr/86Sr and 143Nd/144Nd ratios range from 0.70328 to 0.70351 and from 0.51303 to 0.51309 respectively, with higher and more diverse values being characteristic of earlier ignimbrite units; again suggesting incorporation of surrounding crustal material. In contrast to these results, MELTS modeling using a variety of likely primitive basalts from Gorely shows it is possible to obtain silicic

  20. Cell proliferation on UV-excimer lamp modified and grafted polytetrafluoroethylene

    Czech Academy of Sciences Publication Activity Database

    Švorčík, V.; Ročková, K.; Ratajová, E.; Heitz, J.; Huber, N.; Bäuerle, D.; Bačáková, Lucie; Dvořánková, B.; Hnatowicz, Vladimír

    2004-01-01

    Roč. 217, č. 2 (2004), s. 307-313 ISSN 0168-583X R&D Projects: GA AV ČR IAA5011301; GA ČR GA106/03/0514 Grant - others:CZ-AT(CZ) Aktion 2002-7 Institutional research plan: CEZ:AV0Z5011922 Keywords : polytetrafluoroethylene * UV-beam modification * grafting Subject RIV: EI - Biotechnology ; Bionics Impact factor: 0.997, year: 2004

  1. tex de amapá (Parahancornia fasciculata (Poir Benoist, Apocynaceae: remédio e renda na floresta e na cidade

    Directory of Open Access Journals (Sweden)

    Murilo da Serra Silva

    Full Text Available O estudo abordou a cadeia de produção e de comercialização e os aspectos do consumo do látex medicinal de amapá amargoso (Parahancornia fasciculata em Belém e Ponta de Pedras, no Pará. Nosso objetivo foi investigar diversos aspectos do manejo e uso desse produto, revelando a sua importância na vida de seus produtores e consumidores. Foram utilizados a abordagem da 'cadeia de produção ao consumo' e métodos qualitativos e quantitativos de pesquisa, incluindo pesquisa de mercado, entrevistas com extrativistas, comerciantes e consumidores, oficinas, turnês guiadas e inventário florestal. Os oito mil litros de látex de amapá comercializados anualmente na região de Belém beneficiam, principalmente, consumidores de baixa renda, que têm tradição secular do uso desse látex. A renda obtida com esse produto representa 42% da renda total dos extrativistas com produtos florestais não madeireiros. A grande abundância da espécie e a distribuição diamétrica das árvores indicam possibilidade de regeneração natural. A melhoria na técnica de extração do látex realizada por alguns extrativistas revela que eles têm conhecimento da anatomia da árvore. A tradição de uso e manejo do látex e as características ecológicas da espécie sugerem grande potencial para programas de produção sustentável.

  2. 33 CFR 208.32 - Sanford Dam and Lake Meredith, Canadian River, Tex.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Sanford Dam and Lake Meredith... OF THE ARMY, DEPARTMENT OF DEFENSE FLOOD CONTROL REGULATIONS § 208.32 Sanford Dam and Lake Meredith, Canadian River, Tex. The Bureau of Reclamation, or its designated agent, shall operate the Sanford Dam and...

  3. Self-expandable polytetrafluoroethylene (PTFE)-covered nitinol stent for the palliative treatment of malignant biliary obstruction

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Oong; Jung, Gyoo Sik; Han, Byung Hoon; Shin, Dong Hoon [Gospel Hospital, College of Medicine, Kosin University, Busan (Korea, Republic of); Ko, Ji Ho [Masan Samsung Medical Center, Sungkyunkwan University School of Medicine, Masan (Korea, Republic of)

    2008-06-15

    We wanted to determine the technical and clinical efficacy of placing a self-expandable PTFE-covered nitinol stent for the management of inoperable malignant biliary obstruction. Thirty six patients with inoperable malignant biliary obstructions were treated by placement of self-expandable PTFE-covered nitinol stents (S and G Biotech Corporation, Seongnam, Korea). Clinical evaluation was done with assessment of the serum bilirubin and alkaline phosphatase levels, which were measured before and after stent placement within 1 week, at 1 month and at 3 months. The patient survival rate and stent patency rate were calculated with performing Kaplan-Meier survival analysis. Successful stent placement was achieved in all the patients without procedure-related complication. Pancreatitis as an early complication occurred in two cases. The serum bilirubin and alkaline phosphatase levels were significantly decreased after the procedure. During the follow-up, recurrent obstructive jaundice occurred in six cases; stent migration occurred in four cases and tumor overgrowth occurred in two cases. The survival rates were 97%, 80%, 67% and 59% at 1, 3, 6 and 9 months, respectively. The stent patency rates were 96%, 92%, 86% and 86% at 1, 3, 6 and 9 months, respectively. Self-expandable PTFE-covered nitinol stent placement seems to be technically feasible and effective for the palliative treatment of malignant biliary obstruction.

  4. Self-expandable polytetrafluoroethylene (PTFE)-covered nitinol stent for the palliative treatment of malignant biliary obstruction

    International Nuclear Information System (INIS)

    Yoo, Oong; Jung, Gyoo Sik; Han, Byung Hoon; Shin, Dong Hoon; Ko, Ji Ho

    2008-01-01

    We wanted to determine the technical and clinical efficacy of placing a self-expandable PTFE-covered nitinol stent for the management of inoperable malignant biliary obstruction. Thirty six patients with inoperable malignant biliary obstructions were treated by placement of self-expandable PTFE-covered nitinol stents (S and G Biotech Corporation, Seongnam, Korea). Clinical evaluation was done with assessment of the serum bilirubin and alkaline phosphatase levels, which were measured before and after stent placement within 1 week, at 1 month and at 3 months. The patient survival rate and stent patency rate were calculated with performing Kaplan-Meier survival analysis. Successful stent placement was achieved in all the patients without procedure-related complication. Pancreatitis as an early complication occurred in two cases. The serum bilirubin and alkaline phosphatase levels were significantly decreased after the procedure. During the follow-up, recurrent obstructive jaundice occurred in six cases; stent migration occurred in four cases and tumor overgrowth occurred in two cases. The survival rates were 97%, 80%, 67% and 59% at 1, 3, 6 and 9 months, respectively. The stent patency rates were 96%, 92%, 86% and 86% at 1, 3, 6 and 9 months, respectively. Self-expandable PTFE-covered nitinol stent placement seems to be technically feasible and effective for the palliative treatment of malignant biliary obstruction

  5. Late Neogene Orbitally-Forced Sea Surface Temperature Variability in the Eastern Equatorial Pacific as Measured by Uk'37 and TEX86

    Science.gov (United States)

    Lawrence, K. T.; Pearson, A.; Castañeda, I. S.; Peterson, L.

    2017-12-01

    Key features of late Neogene climate remain uncertain due to conflicting records derived from different sea surface temperature (SST) proxies. To resolve these disputes, it is necessary to explore both the consistencies and differences between paleotemperature estimates from critical oceanographic regimes. Here, we report orbital-scale climate variability at ODP Site 846 in the Eastern Equatorial Pacific (EEP) in the interval from 5-6 Ma using alkenone and TEX86 temperature estimates. Results from both proxies are very similar in their secular trends and magnitude of long-term temperature change; and spectral analysis demonstrates that the records are coherent and in-phase or nearly in-phase in both the obliquity and precession bands. However, we find that the temperatures reconstructed by TEX86 are consistently offset towards colder values by 2ºC with orbital-scale variations approximately twice the amplitude of the Uk'37 derived estimates. Both temperature records are antiphased - i.e. "colder" - at higher sediment alkenone concentrations, a qualitative indicator of increased glacial productivity. Temperature differences between the proxies are accentuated during glacial intervals in contrasts to modern observations of EEP surface and subsurface temperatures, which show that thermocline temperatures are fairly stable, and thus by analogy, glacial cooling and/or enhanced upwelling should have reduced rather than accentuated temperature gradients in the upper water column. Therefore, arguments that Uk'37 corresponds to temperature variability in the surface, while TEX86 responds to the subsurface, may be too simplistic. Instead, it appears generally true that high-productivity environments, including the EEP, tend to have negative TEX86 anomalies. This may reflect a dual dependence of TEX86 records on both water column temperature and local productivity. Overall, our data suggest that in the EEP and likely in other upwelling zones, paleotemperature data derived

  6. Growth of muscle cells on plasma-treated and gold nanoparticles-grafted polytetrafluoroethylene

    Czech Academy of Sciences Publication Activity Database

    Řezníčková, A.; Makajová, Z.; Kasálková-Slepičková, N.; Kolská, Z.; Bačáková, Lucie; Švorčík, V.

    2014-01-01

    Roč. 23, č. 3 (2014), s. 227-236 ISSN 1026-1265 R&D Projects: GA ČR(CZ) GBP108/12/G108 Institutional support: RVO:67985823 Keywords : polytetrafluoroethylene ( PTFE ) * nanoparticles * biocompatibility Subject RIV: EI - Biotechnology ; Bionics Impact factor: 1.806, year: 2014

  7. Water Exploitation and Its Outcomes Caused by Capitalism as Reflected on Gore Verbinski's Rango Movie

    OpenAIRE

    SETIAWAN, DANIEL NUGRAHA

    2014-01-01

    Nugraha Setiawan, Daniel. 2014. Water Exploitation and Its Outcome Caused byCapitalism as Reflected on Gore Verbinski's Rango Movie. Study Program ofEnglish, Universitas Brawijaya.Supervisor: Yusri Fajar, Co-supervisor: Melania Shinta Harendika.Keywords: water exploitation, environment, capitalism, Rango movie. Water exploitation threats ecosystem and causes a great damage to environment. One of the causes of the water exploitation is capitalism. The movie entitled Rango reveals some causes a...

  8. Observations of Radical Precursors during TexAQS II: Findings and Implications

    Science.gov (United States)

    Olaguer, E. P.; Lefer, B. L.; Rappenglueck, B.; Pinto, J. P.

    2009-12-01

    The Texas Environmental Research Consortium (TERC) sponsored and helped organize significant components of the Second Texas Air Quality Study (TexAQS II). Some of the TERC-sponsored experiments, most notably those associated with the TexAQS II Radical and Aerosol Measurement Project (TRAMP) sited on top of the Moody Tower at the University of Houston, found evidence for the importance of short-lived radical sources such as formaldehyde (HCHO) and nitrous acid (HONO) in increasing ozone productivity. During TRAMP, daytime HCHO pulses as large as 32 ppb were observed and attributed to industrial activities upwind in the Houston Ship Channel (HSC), and HCHO peaks as large as 52 ppb were detected by in-situ surface monitors in the HSC. In addition, an instrumented Piper Aztec aircraft observed plumes of apparent primary formaldehyde in flares from petrochemical facilities in the HSC. In one such combustion plume, depleted of ozone by large NOx emissions, the Piper Aztec measured an HCHO-to-CO ratio three times that of mobile sources. HCHO from uncounted primary sources or ozonolysis of underestimated olefin emissions could significantly increase ozone productivity in Houston beyond previous expectations. Simulations with the CAMx model show that additional emissions of HCHO from industrial flares can increase peak ozone in Houston by up to 30 ppb, depending on conditions in the planetary boundary layer. Other findings from TexAQS II include significant concentrations of HONO throughout the day, well in excess of current air quality model predictions, with large nocturnal vertical gradients indicating a surface or near-surface source of HONO, and large concentrations of night-time radicals (~30 ppt HO2). Additional HONO sources could increase daytime ozone by more than 10 ppb. Improving the representation of primary and secondary HCHO and HONO in air quality models could enhance the effectiveness of simulated control strategies, and thus make ozone attainment

  9. Candidates stick to party guns. In lieu of new healthcare plans, Bush, Gore follow party reform proposals.

    Science.gov (United States)

    Gardner, J; Hallam, K

    2000-07-03

    As the Democratic and GOP nominating conventions approach next month, presumptive nominees Al Gore and George W. Bush are offering no new healthcare plans, both preferring to ride the healthcare waves already set in motion by their respective party's leadership. And the really interesting thing is, the plans aren't that different. Call it creeping incrementalism.

  10. Caracterização da hipersensibilidade a luvas de látex em profissionais da odontologia = Rubber latex gloves hypersensitivities in dental workers

    Directory of Open Access Journals (Sweden)

    Flávia Sukekava

    2007-01-01

    Full Text Available As reações alérgicas ao látex vêm aumentando em profissionais da saúde e se manifestam como um incômodo local ou sintomatologia sistêmica. Para conhecer a freqüência das manifestações alérgicas nos usuários de luvas de látex foi realizada busca entre os profissionais da odontologia via aplicação de questionários. Foram aplicados 450questionários e, dentre os respondedores (140, 19% relataram manifestar reações locais ao contato com as luvas de látex e 5% reações sistêmicas a outros produtos de látex. Cerca de 2,5% declararam dermatite de contato e reações sistêmicas (anafiláticas, 1,5% apenas dermatite de contato e 1% sintomas de anafilaxia ao uso das luvas. Vinte por cento dos profissionais atenderam pacientes com alergia ao látex e 29% declararam questionar, durante a anamnese, a respeito de alergia ao látex. As reações alérgicas a luvas de látex foram freqüentes e é objeto de preocupação entre os profissionais da odontologia.Allergic reactions to natural rubber latex have increased in dental practice affecting both the professional and the patients. Allergic reactions may range from skin disease to asthma and anaphylaxis. This study aimed at determining the incidence of latex gloves allergy amongdental care workers. 450 allergy questionnaires were used to collect information on latex gloves reactions and 140 dental works answered them. Latex gloves reaction occurred in 19% of them and 5% reported allergic reactions to other latex products. 2.5% reported symptoms suggesting contact dermatitis and anaphylaxis hypersensitivities, 1.5% contact dermatitis, and 1% reported anaphylaxis symptoms when wearing them. 20% of them had patients who presented symptoms suggestive of anaphylaxis hypersensitivity to rubber gloves latex. Our study confirms that rubber latex gloves reactions are frequent among dental care workers, and dentists must be aware of the latex allergy in dental practice.

  11. Tribological behavior of polytetrafluoroethylene coating reinforced with black phosphorus nanoparticles

    Science.gov (United States)

    Peng, Shiguang; Guo, Yue; Xie, Guoxin; Luo, Jianbin

    2018-05-01

    This study compares the tribological performance of polytetrafluoroethylene (PTFE) thin film coating reinforced with black phosphorus (BP) or ball-milled graphite (BMG) nanoparticles, so as to elucidate their mechanism of action under reciprocating sliding test conditions. PTFE coatings with 0.5 wt.% BMG (BMG/PTFE) and 0.5 wt.% BP (BP/PTFE) were prepared on GCr15 bearing steel disk by using a spin coater. The friction and wear tests were carried out by using the ball-on-disk tribometer under a normal load of 1 N (contact pressure: 780 MPa), a frequency of 2 Hz, and 4.2 mm sliding displacement amplitude. The surface roughness, wear volume and surface morphology of the coatings were characterized by the three-dimensional white light, and Energy Dispersive X-ray Detector (EDX) analysis coupled with environmental scanning electron microscope (ESEM). It is found that BP/PTFE coating has better anti-wear and anti-friction performances than those of pure PTFE or BMG/PTFE coating. The coating with BP nanoparticles shows excellent tribological properties with the wear volume decreased from 3.52 × 106 μm3 to 1.64 × 106 μm3 and the coefficient of friction (COF) decreased from 0.117 to 0.046. More importantly, the BP layer probably expands and absorbs much energy due to its negative Poisson's ratio phenomenon under reciprocating sliding, and effectively reducing furrow and adhesive wear.

  12. Radiation processing for carbon fiber-reinforced polytetrafluoroethylene composite materials

    International Nuclear Information System (INIS)

    Oshima, Akihiro; Udagawa, Akira; Morita, Yousuke

    2001-01-01

    The present work is an attempt to evaluate the performance of the fiber composites with crosslinked polytetrafluoroethylene (PTFE) as a polymer matrix by radiation. The uni-directional carbon fiber-reinforced composites were fabricated with PTFE fine powder impregnation method and then crosslinked by electron beams irradiation under selective conditions. The carbon fiber-reinforced crosslinked PTFE composites show good mechanical properties compared with crosslinked PTFE. The radiation resistance of crosslinked PTFE composites is improved more than that of crosslinked resin without fiber. (author)

  13. TEX-SIS Occ/Tec Non-Returning Student Follow-Up, Volume 1, Number 1.

    Science.gov (United States)

    Gose, Frank

    In 1981, selected data about nonreturning occupational/technical students were collected at Yavapai College using the TEX-SIS follow-up system, which was developed by the Texas Education Agency and Texas Coordinating Board for Universities and Colleges. A sample of 449 students was selected from the approximately 900 students who had enrolled in…

  14. Membrane technologies for liquid radioactive waste treatment

    International Nuclear Information System (INIS)

    Chmielewski, A.G.; Harasimowicz, M.; Zakrzewska-Trznadel, G.

    1998-01-01

    At Institute of Nuclear Chemistry and Technology (INCT) the membrane method for purification of radioactive wastes applied such processes as ultrafiltration (UF), 'seeded' ultrafiltration and reverse osmosis (RO) was developed. On the basis of the results obtained in laboratory experiments the pilot plant for radioactive effluents treatment was built. The plant was composed of UF unit (AMICON H 26P30 capillary module) and two RO units (NITTO NTR 739 HF S-4 spiral wound LPRO modules). The capacity of the pilot plant was up to 200 L/h and the specific activity of wastes purified in the system - below 10 4 Bq/L. Decontamination factor for entire system is higher than 5 x10 3 . Another possibility for radioactive wastes treatment is membrane distillation (MD), non-isothermal process employing hydrophobic polymer membrane, which is developed at INCT now. Preliminary tests with liquid radwaste were carried out on laboratory unit with permeation test-cell holding flat sheet membrane. As a hydrophobic barrier membranes made of two polymers were used: polytetrafluoroethylene (PTFE) and polypropylene (PP). The process was arranged in direct contact membrane distillation configuration. The permeate condensed directly in the cold stream (distilled water) and retentate was enriched in radionuclides. The further experiments carried out with capillary module BFMF 06-30-33 (Euro-Sep Ltd.) with polypropylene capillaries, diameter 0.33 mm and cut off 0.6 μm proved previous results. A pilot plant employing GORE-TEX membrane distillation was constructed. The plant can clean the low-level radioactive wastes from nuclear centre, at a throughput about 0.05 m 3 /h

  15. Diffusion layer characteristics for increasing the performance of activated carbon air cathodes in microbial fuel cells

    KAUST Repository

    Zhang, Xiaoyuan; He, Weihua; Yang, Wulin; Liu, Jia; Wang, Qiuying; Liang, Peng; Huang, Xia; Logan, Bruce E.

    2016-01-01

    The characteristics of several different types of diffusion layers were systematically examined to improve the performance of activated carbon air cathodes used in microbial fuel cells (MFCs). A diffusion layer of carbon black and polytetrafluoroethylene (CB + PTFE) that was pressed onto a stainless steel mesh current collector achieved the highest cathode performance. This cathode also had a high oxygen mass transfer coefficient and high water pressure tolerance (>2 m), and it had the highest current densities in abiotic chronoamperometry tests compared to cathodes with other diffusion layers. In MFC tests, this cathode also produced maximum power densities (1610 ± 90 mW m−2) that were greater than those of cathodes with other diffusion layers, by 19% compared to Gore-Tex (1350 ± 20 mW m−2), 22% for a cloth wipe with PDMS (1320 ± 70 mW m−2), 45% with plain PTFE (1110 ± 20 mW m−2), and 19% higher than those of cathodes made with a Pt catalyst and a PTFE diffusion layer (1350 ± 50 mW m−2). The highly porous diffusion layer structure of the CB + PTFE had a relatively high oxygen mass transfer coefficient (1.07 × 10−3 cm s−1) which enhanced oxygen transport to the catalyst. The addition of CB enhanced cathode performance by increasing the conductivity of the diffusion layer. Oxygen mass transfer coefficient, water pressure tolerance, and the addition of conductive particles were therefore critical features for achieving higher performance AC air cathodes.

  16. Gore-Mbeki Binational Commission integrated housing program. Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-12-31

    This report documents the work done under Grant DE-FG36-97GO10209, Innovative Renewable Energy Technology Transfer Program. PEER Consultants, PC, and its subcontractor, PEER Africa (Pty.) Ltd., received an $88,000.00 grant to plan and build two energy efficient homes in the black township of Gugulethu in Cape Town, South Africa. These demonstration homes were given to the people of South Africa as a gesture of goodwill by the US government as part of the Gore-Mbeki Binational Commission (BNC) agreements and cooperation. The BNC is the term used to describe the agreement to work together by the US and the South African governments for economic development of South Africa in the areas of energy, commerce, agriculture, housing, and transportation. The BNC was formed in 1995. This project under the auspices of the BNC started in September 1996. The DOE-funded portion was performed between January 11, 1997 and February 28, 1997.

  17. Mass production of bacterial communities adapted to the degradation of volatile organic compounds (TEX).

    Science.gov (United States)

    Lapertot, Miléna; Seignez, Chantal; Ebrahimi, Sirous; Delorme, Sandrine; Peringer, Paul

    2007-06-01

    This study focuses on the mass cultivation of bacteria adapted to the degradation of a mixture composed of toluene, ethylbenzene, o-, m- and p-xylenes (TEX). For the cultivation process Substrate Pulse Batch (SPB) technique was adapted under well-automated conditions. The key parameters to be monitored were handled by LabVIEW software including, temperature, pH, dissolved oxygen and turbidity. Other parameters, such as biomass, ammonium or residual substrate concentrations needed offline measurements. SPB technique has been successfully tested experimentally on TEX. The overall behavior of the mixed bacterial population was observed and discussed along the cultivation process. Carbon and nitrogen limitations were shown to affect the integrity of the bacterial cells as well as their production of exopolymeric substances (EPS). Average productivity and yield values successfully reached the industrial specifications, which were 0.45 kg(DW)m(-3) d(-1) and 0.59 g(DW)g (C) (-1) , respectively. Accuracy and reproducibility of the obtained results present the controlled SPB process as a feasible technique.

  18. Orthodontic tooth movement after extraction of previously autotransplanted maxillary canines and ridge augmentation.

    Science.gov (United States)

    Collett, A R; Fletcher, B

    2000-12-01

    A case report is detailed in which autotransplanted maxillary canines were removed and the spaces closed. Substantial surrounding bone loss was associated with the upper right canine, and a bone graft was needed to reestablish normal dentoalveolar ridge morphology. Bone was taken from the maxillary tuberosity and placed in the canine extraction site, fixed with a bone screw, and covered with GoreTex. Seven months after placement of the bone graft, the GoreTex and stabilizing screw were removed to allow for consolidation of the bone. The upper left canine and lower second premolars were extracted, and fixed appliances were placed in both arches to align the teeth and close the spaces. Protraction of the upper right first premolar and retraction of the lateral incisor into the graft site were kept slow and constant with continued periodontal assessment. During the space closure, there was some concern that the bone in the graft site might resorb, leaving the teeth with compromised periodontal support. However, no significant periodontal attachment loss occurred despite ongoing concern about the amount of keratinized tissue. Perhaps the relatively slow rate of tooth movement provided for bone to be maintained and recreated ahead of the tooth. Almost complete closure of the upper canine extraction spaces was achieved. The upper premolars were substituted for the maxillary canines, and unfavorable prosthetic options were thus avoided. The lower arch was aligned, and the extraction spaces completely closed.

  19. Health assessment for Tex Tin Corporation, National Priorities List Site, Texas City, Texas, Region 6. CERCLIS No. TXD062113329. Preliminary report

    International Nuclear Information System (INIS)

    1990-01-01

    The Tex Tin Corporation facility, formerly Gulf Chemical and Metallurgical Corporation, is a proposed National Priorities List site located in Texas City, Galveston County, Texas. Tex Tin previously operated as a primary tin smelter, but currently operates as a copper smelter. Significant concentrations of metals (antimony, arsenic, barium, cadmium, chromium, copper, lead, manganese, mercury, nickel, silver, tin, and zinc) have been detected on-site in surface water, groundwater, and soil. Significant concentrations of metals (arsenic, cadmium, chromium, lead, nickel, and tin) have also been detected in ambient air samples collected off-site. Some remediation activities have occurred on-site including the closure of a 19-million-gallon ferric chloride pond and the removal of approximately 4,000 drums containing radioactive material. The Tex Tin site poses a potential public health concern for on-site workers, residents living in nearby neighborhoods, and possibly for a limited number of residents on private wells located within approximately one mile of the site

  20. Microfabrication of high quality polytetrafluoroethylene films by synchrotron radiation

    International Nuclear Information System (INIS)

    Yoshida, A.; Matsumoto, E.; Yamada, H.; Okada, H.; Wakahara, A.

    2003-01-01

    We deposited polytetrafluoroethylene (PTFE) thin films both from the PTFE target by using synchrotron radiation (SR) beam and from PTFE emulsion by spin-coat process. The X-ray diffraction analyses showed a sharp peak due to (1 0 0) PTFE crystalline part, and only C-F 2 bonding was found in Fourier transform infrared spectrophotometer spectra. From electron spectroscopy for chemical analysis measurements, no impurities were found. The fabricated PTFE films were easily etched by SR beam on the limited area of the surface on a microscale through a suitably patterned mask

  1. Initial H2O content and conditions of parent magma origin for Gorely volcano (Southern Kamchatka) estimated by trace element thermobarometry

    Science.gov (United States)

    Nazarova, D. P.; Portnyagin, M. V.; Krasheninnikov, S. P.; Mironov, N. L.; Sobolev, A. V.

    2017-01-01

    The formation conditions of the parental magmas of Gorely volcano, which is located behind a volcanic front in Southern Kamchatka, have been evaluated using the modern methods of micro-element thermobarometry. These magmas contained 1.7 ± 0.8 (2σ) wt % of H2O, the majority (82%) of which has been lost from inclusions. They crystallized at 1121 ± 17°C and an oxygen fugacity of ΔQFM 1.2 ± 0.2, and could have been produced by about 11% melting of an enriched MORB source (E-DMM) at a temperature of about 1270°C, and a pressure of about 1.5 GPa. A distinctive feature of Gorely volcano, compared with frontal volcanoes of Kamchatka, is the unusually high temperature (925 ± 20°C) of formation of the subduction component corresponding to the region of existence of water-bearing melts.

  2. Late Pleistocene temperature history of Southeast Africa: A TEX(86) temperature record from Lake Malawi

    NARCIS (Netherlands)

    Woltering, M.; Johnson, T.C.; Werne, J.P.; Schouten, S.; Sinninghe Damsté, J.S.

    2011-01-01

    We present a TEX86-derived surface water temperaturerecord for LakeMalawi that provides the first continuous continental record of temperature variability in the continental tropics spanning the past ∼ 74 kyr with millennial-scale resolution. Average temperature during Marine Isotope Stage (MIS) 5A

  3. Prevalência de sinais/sintomas sugestivos de sensibilização ao látex em profissionais de saúde Prevalencia de señales/síntomas sugestivos de sensibilidad al l átex en profesionales de la salud Prevalence of signs/symptoms suggestive of latex sensitization in health care workers

    Directory of Open Access Journals (Sweden)

    Lígia Andrade da Silva Telles Mathias

    2006-04-01

    Full Text Available JUSTIFICATIVA E OBJETIVOS: As referências na literatura sobre reações aos derivados do látex têm aumentado significativamente nos últimos anos. Faltam, entretanto, dados do nosso país relativos à prevalência de sensibilização ao látex nos profissionais da área da saúde. O objetivo deste estudo foi avaliar a prevalência de sinais/sintomas sugestivos de sensibilização ao látex em profissionais da área da saúde. MÉTODO: Após aprovação pelo Comitê de Ética foram selecionados indivíduos pertencentes ao quadro da instituição: funcionários do Setor de Limpeza, Contabilidade e Divisão de Enfermagem do Centro Cirúrgico; Médicos da Cirurgia, Ginecologia, Obstetrícia, Anestesiologia, Unidade de Terapia Intensiva e Clínica Médica. Após consentimento informado, os indivíduos foram submetidos a um questionário sobre: idade, sexo, categoria profissional; tipo e tempo de contato profissional com derivados do látex; tipo de luva; sinais/sintomas sugestivos de sensibilização ao látex dentro e fora do ambiente hospitalar; sinais/sintomas sugestivos de atopia e de alergia a alimentos. RESULTADOS: Foram avaliados 326 questionários (193 mulheres e 133 homens, com idade entre 30 e 73 anos. Setenta e cinco por cento dos entrevistados apresentaram até 10 anos de tempo na profissão. A prevalência dos sinais/sintomas sugestivos de sensibilização ao látex dentro do ambiente hospitalar em relação aos grupos compostos pelos funcionários do Setor de Contabilidade (não expostos a derivados do látex no ambiente de trabalho e o restante dos indivíduos (expostos a derivados do látex no ambiente de trabalho mostrou diferença significativa (p JUSTIFICATIVA Y OBJETIVOS: Las referencias en la literatura sobre reacciones a los derivados del látex han aumentado significativamente en los últimos años. Sin embargo faltan datos de nuestro país relativos a la prevalencia de sensibilidad al látex en los profesionales del

  4. ZnO1-xTex and ZnO1-xSx semiconductor alloys as competent materials for opto-electronic and solar cell applications: a comparative analysis

    Institute of Scientific and Technical Information of China (English)

    Utsa Das; Partha P.Pal

    2017-01-01

    ZnO1-xTex ternary alloys have great potential to work as a photovoltaic (PV) absorber in solar cells.ZnO1-xSx is also a ZnO based alloy that have uses in solar cells.In this paper we report the comparative study of various parameters of ZnO1-xTex and ZnO1-xSx for selecting it to be a competent material for solar cell applications.The parameters are mainly being calculated using the well-known VCA (virtual crystal approximation) and VBAC (Valence Band Anti-Crossing) model.It was certainly being analysed that the incorporation of Te atoms produces a high band gap lower than S atoms in the host ZnO material.The spin-orbit splitting energy value of ZnO1-xTex was found to be higher than that of ZnO1-xSx.Beside this,the strain effects are also higher in ZnO1-xTex than ZnO1-xSx.The remarkable notifying result which the paper is reporting is that at a higher percentage of Te atoms in ZnO1-xTex,the spin-orbit splitting energy value rises above the band gap value,which signifies a very less internal carrier recombination that decreases the leakage current and increases the efficiency of the solar ceil.Moreover,it also covers a wide wavelength range compared to ZnO1-xSx.

  5. Non-destructive examination of a time capsule recovered from the Gore Park excavations, Hamilton, Ontario

    International Nuclear Information System (INIS)

    MacDonald, B.L.; Vanderstelt, J.

    2015-01-01

    Non-destructive analytical techniques are becoming increasingly important for the study of objects of cultural heritage interest. We present a study that applied two techniques: x-ray fluorescence (XRF) and neutron radiography, for the investigation of a time capsule recovered from an urban construction site in Gore Park, Hamilton. XRF analysis revealed the composition of the artifact, while n-radiography showed that its contents remained intact after being interred for 91 years. Results of this study demonstrate the value of non-destructive techniques for the analysis and preservation of cultural heritage. (author)

  6. Radiation degradation and crosslinking of polytetrafluoroethylene and its application

    International Nuclear Information System (INIS)

    Wu Guozhong; Wang Mouhua; Tang Zhongfeng

    2009-01-01

    Polytetrafluoroethylene (PTFE) is a high-performance engineering plastic and known as a typical material of radiation degradation. PTFE can be degraded by radiation under various conditions and PTFE micro-powder is usually fabricated by a combination of radiation and milling. PTFE can also be crosslinked by irradiation in the melt state (330∼340 degree C). The materials can be applied as a special additive due to its excellent wear resistance. Crosslinked PTFE may also be applied in lithography and fuel cell membrane in the future. In this paper, history and application of PTFE degradation and crosslinking products are reviewed. (authors)

  7. Deposition of nanostructured fluorocarbon plasma polymer films by RF magnetron sputtering of polytetrafluoroethylene

    Energy Technology Data Exchange (ETDEWEB)

    Kylian, Ondrej, E-mail: ondrej.kylian@gmail.com; Drabik, Martin; Polonskyi, Oleksandr; Cechvala, Juraj; Artemenko, Anna; Gordeev, Ivan; Choukourov, Andrei; Matolinova, Iva; Slavinska, Danka; Biederman, Hynek, E-mail: bieder@kmf.troja.mff.cuni.cz

    2011-07-29

    The RF magnetron sputtering of polytetrafluoroethylene target is studied with the aim to find out conditions leading to the deposition of super-hydrophobic thin films. It is shown that such coatings can be prepared at elevated pressures and a longer distance between the sputtered target and the substrate. This is explained by an increase in the density of longer C{sub x}F{sub y} molecules that reach the substrate and a lower flux of ions and CF{sub 2} radicals on the surface of growing film under such deposition conditions, as observed by optical emission spectroscopy and mass spectrometry. Such changes in plasma composition result in a deposition of rough films having F/C ratio close to 2 as observed by scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. These findings clearly distinguish our results from the previous investigations of polytetrafluoroethylene sputtering performed at shorter distances from the target, where either low F/C ratio or low roughness of the deposited films did not allow reaching super-hydrophobic character of the coatings.

  8. Impact of water depth on the distribution of iGDGTs in the surface sediments from the northern South China Sea: applicability of TEX86 in marginal seas

    Science.gov (United States)

    Chen, Jiali; Hu, Pengju; Li, Xing; Yang, Yang; Song, Jinming; Li, Xuegang; Yuan, Huamao; Li, Ning; Lü, Xiaoxia

    2018-03-01

    The TEX 86 H paleothermometer on the base of isoprenoid glycerol dialkyl glycerol tetraethers (iGDGTs) has been widely applied to various marine settings to reconstruct past sea surface temperatures (SSTs). However, it remains uncertain how well this proxy reconstructs SSTs in marginal seas. In this study, we analyze the environmental factors governing distribution of iGDGTs in surface sediments to assess the applicability of TEX 86 H paleothermometer in the South China Sea (SCS). Individual iGDGT concentrations increase gradually eastwards. Redundancy analysis based on the relative abundance of an individual iGDGT compound and environmental parameters suggests that water depth is the most influential factor to the distribution of iGDGTs, because thaumarchaeota communities are water-depth dependent. Interestingly, the SST difference (Δ T) between TEX 86 H derived temperature and remote-sensing SST is less than 1°C in sediments with water depth>200 m, indicating that TEX 86 H was the robust proxy to trace the paleo-SST in the region if water depth is greater than 200 m.

  9. Alergia ao látex: diagnóstico acidental após procedimento urológico. Relato de caso Alergia al látex: diagnóstico accidental después procedimiento urológico. Relato de caso Latex allergy: accidental diagnosis after urological procedure. Case report

    Directory of Open Access Journals (Sweden)

    Bruno Araújo Verdolin

    2003-08-01

    Full Text Available JUSTIFICATIVA E OBJETIVOS: A alergia aos produtos derivados do látex tem-se tornado um problema de grandes proporções, afetando tanto os pacientes como os profissionais da saúde. O objetivo deste relato é descrever o diagnóstico acidental de alergia ao látex após uma cirurgia urológica sob raquianestesia em que o paciente apresentou quadro clínico compatível ao choque anafilático. RELATO DO CASO: Paciente do sexo masculino, 16 anos, portador de lesão de uretra posterior e em uso de sonda vesical por 3 anos, devido a duas cirurgias prévias sem sucesso. Durante o procedimento cirúrgico sob raquianestesia com bupivacaína, o paciente apresentou, logo após a exploração da cavidade abdominal, confusão, dispnéia, prurido e eritema generalizado, broncoespasmo, hipotensão arterial e taquicardia. Houve melhora gradativa das alterações apresentadas com o tratamento instituído. Durante a permanência no hospital, o paciente apresentou, ao soprar um balão de festa, urticária de contato na face e broncoespasmo, que foram prontamente tratados. O teste de punção cutânea e a dosagem de IgE específica para o látex confirmaram a hipótese diagnóstica de alergia ao látex. CONCLUSÕES: A combinação da história clínica do paciente com os dados laboratoriais permitiram a identificação do quadro de alergia ao látex. Esta entidade vem apresentando grande importância recentemente, principalmente naqueles pacientes de risco, como é o do presente caso.JUSTIFICATIVA Y OBJETIVOS: La alergia a los productos derivados del látex se han convertido en un problema de grandes proporciones, afectando tanto los pacientes como también, los profesionales de la salud. El objetivo de este relato es describir el diagnóstico accidental de alergia al látex después de una cirugía urológica sobre raquianestesia en que el paciente presentó cuadro clínico compatible con choque anafilático. RELATO DE CASO: Paciente del sexo masculino, 16 a

  10. Liberação de componentes do extrato de Casearia sylvestris Swartz empregando membranas de látex natural como suporte

    OpenAIRE

    Alberto Trecco; Felipe Azevedo Borges; Elaise G. Pierri; André Gonzaga dos Santos; Chung Man Chin; Rondinelli Donizetti Herculano

    2014-01-01

    A membrana de látex natural (NRL – Natural Rubber Latex), manipulada a partir do látex extraído da seringueira Hevea brasiliensis, tem apresentado grande potencial de aplicação no campo da biomedicina e dos biomateriais. Graças a sua biocompatibilidade e baixa taxa de rejeição, ela tem sido utilizada para próteses e enxertos, atuando como estimulante da angiogênese, adesão celular e barreira física a agentes infecciosos. Além dessas aplicações, as membranas são utiliza...

  11. Solar concentrator panel and gore testing in the JPL 25-foot space simulator

    Science.gov (United States)

    Dennison, E. W.; Argoud, M. J.

    1981-01-01

    The optical imaging characteristics of parabolic solar concentrator panels (or gores) have been measured using the optical beam of the JPL 25-foot space simulator. The simulator optical beam has been characterized, and the virtual source position and size have been determined. These data were used to define the optical test geometry. The point source image size and focal length have been determined for several panels. A flux distribution of a typical solar concentrator has been estimated from these data. Aperture photographs of the panels were used to determine the magnitude and characteristics of the reflecting surface errors. This measurement technique has proven to be highly successful at determining the optical characteristics of solar concentrator panels.

  12. Developing Tele-Operated Laboratories for Manufacturing Engineering Education. Platform for E-Learning and Telemetric Experimentation (PeTEX

    Directory of Open Access Journals (Sweden)

    A. Erman Tekkaya

    2010-09-01

    Full Text Available The aim of the PeTEX-project is to establish an e-Learning platform for the development, implementation, and delivery of educational training programs in the field of manufacturing engineering. The PeTEX team designs both: a technical platform for eLearning based on “Moodle” including distributed tele-operated experimentation facilities, and didactic and socio-technical requirements for a successful online learning community. User interfaces are deployed for remote access to instruments, data analysis and multiplexed data access via network protocols. Hence, the platform provides complex tools in order to perform various activities to support the educational process, from telemetric experimentation to virtual project groups for an entire community to the purpose of domain specific learning. This paper describes important steps of interdisciplinary participatory design and development of a remote lab-prototype in the field of manufacturing engineering.

  13. Demonstration of the AGI Universal Samplers (F.K.A. the GORE Modules) for Passive Sampling of Groundwater

    Science.gov (United States)

    2014-03-27

    and lower Hen- ry’s Law constants are biased low (Anderson 2013). In this instance, me- thyl tert-butyl ether (MTBE) is lost entirely and 1,2...coolers full of ice or blue ice to transport samples to the laboratory. One limitation associated with using the GORE Module is that, like all no- purge...was taken from Dunbar et al. (2001). A regional geologic and geomorphic model was developed for the Aberdeen Prov- ing Ground (APG). Regional

  14. MR angiography in diagnosing and following up the treatment result: arteria lusoria

    International Nuclear Information System (INIS)

    Vogl, T.J.; Juergens, M.; Harms, J.; Pegios, W.; Zimmermann, A.; Hetzer, R.; Felix, R.

    1994-01-01

    Diagnostic and therapeutic procedures are presented in a 29-year-old female patient who suffered from severe dysphagia and rapid loss in weight. In the conventional X-ray examination and barium swallow an aberrant right subclavian artery was suspected. MR imaging (MRI) and MR angiography (MRA) were done to plan the surgical correction. Post-operative MRA documented exactly the complex topography after surgical correction and the flow pattern in the implanted Gore-Tex stretch graft prosthesis. Non-invasive MR angiography renders possible the concrete planning of complex corrections of thoracic vessels replacing invasive catheter angiography. (orig.) [de

  15. Introducing TEX86 as a Water pH Proxy for Alkaline Lakes on the Tibetan Plateau

    Science.gov (United States)

    Wang, M.; Tian, Q.; Li, X.; Liang, J.; Yue, H.; Hou, J.

    2017-12-01

    Lake water pH represents one of the most important indicators for lake evolution and factors influencing the evolution of aquatic ecosystem, however, which is less studied on the Tibetan Plateau (TP). Applicability of diatom assemblages, an effective proxy of lake water pH variation in freshwater lakes, is highly limited on the TP because the widespread distribution of alkaline lakes is unfavorable for preservation of diatom shells. Glycerol dialkyl glycerol tetraethers (GDGTs) are a series of specific membrane lipids biosynthesized by archaea and bacteria, which appear to be a promising method to reflect lake water pH variation. Here we present the distribution of iGDGTs compounds in surface sediments across the TP to discuss the effect of various environmental factors on iGDGTs distribution. The results show that TEX86 is a promising proxy for lake water pH in high-elevation alkaline lakes, as water pH appears to be the most important factor to affect the cyclization of iGDGTs. We proposed the water pH calibration for lakes (salinitywater pH. The TEX86-derived pH at Bangong Co varied from 8.69 to 9.49 since the last 16 kyr BP, which is generally consistent with precipitation isotope variation that was reconstructed from leaf wax D/H ratios in the same sediment core, suggesting the lake water pH was mainly controlled by local hydrology. We believe that TEX86 will be able to infer past water pH of alkaline lakes over TP and could be a potentially useful tool for reconstructing pH in alkaline lakes worldwide after regional calibrated.

  16. Non-Fourier heat conduction and phase transition in laser ablation of polytetrafluoroethylene (PTFE)

    Science.gov (United States)

    Zhang, Yu; Zhang, Daixian; Wu, Jianjun; Li, Jian; He, Zhaofu

    2017-11-01

    The phase transition in heat conduction of polytetrafluoroethylene-like polymers was investigated and applied in many fields of science and engineering. Considering more details including internal absorption of laser radiation, reflectivity of material and non-Fourier effect etc., the combined heat conduction and phase transition in laser ablation of polytetrafluoroethylene were modeled and investigated numerically. The thermal and mechanic issues in laser ablation were illustrated and analyzed. Especially, the phenomenon of temperature discontinuity formed in the combined phase transition and non-Fourier heat conduction was discussed. Comparisons of target temperature profiles between Fourier and non-Fourier heat conduction in melting process were implemented. It was indicated that the effect of non-Fourier plays an important role in the temperature evolvement. The effect of laser fluence was proven to be significant and the thermal wave propagation was independent on the laser intensity for the non-Fourier heat conduction. Besides, the effect of absorption coefficients on temperature evolvements was studied. For different ranges of absorption coefficients, different temperature evolvements can be achieved. The above numerical simulation provided insight into physical processes of combined non-Fourier heat conduction and phase transition in laser ablation.

  17. Caracterización de diversas fracciones del látex Carica papaya como biocatalizadores en la hidrólisis de triglicéridos

    Directory of Open Access Journals (Sweden)

    Rivera, I.

    2014-03-01

    Full Text Available Carica papaya latex contains interesting enzymes; the best known is papain, but lipolytic activity is also present. Due to the complexity of the latex polymeric matrix, it has not been possible to completely isolate enzymes responsible of lipolytic activity. The aim of this work was to characterize the lipolytic activity in the raw latex (CPLtx and two partially purified fractions of papaya latex (without protease, CPL-p and without esterase CPL-e. Thermostability, optimal temperature and pH in the hydrolysis of two model triglycerides (tributyrin and triolein and the selectivity towards triglycerides with different chain lengths were determined. The lipolytic activity of these biocatalysts in the hydrolysis of tributyrin and olive oil was similar to other commercially available immobilized microbial lipases (RM IM and Novozyme 435.El látex de Carica papaya es fuente de interesantes enzimas, la más conocida es la papaína, pero la actividad lipolítica también está presente. No obstante, debido a la complejidad de la matriz polimérica del látex, hasta la fecha no ha sido posible aislar las enzimas responsables de la actividad lipolítica del látex. Este trabajo está dedicado a la caracterización de la actividad lipolítica en el látex crudo (CPLtx y dos fracciones parcialmente purificadas de látex de papaya (sin proteasas, CPL-p y sin esterasas, CPL-e, a las cuales se determinaron la termostabilidad, temperatura y pH óptimos en la hidrólisis de dos triglicéridos modelo (tributirina y trioleina, así como la selectividad hacia triglicéridos con diferentes longitudes de cadena. Los tres presentaron actividades lipolíticas en hidrólisis de tributirina y aceite de oliva comparables con otras lipasas microbianas inmovilizadas disponibles comercialmente (RM IM y Novozyme 435.

  18. Wet-chemical approach for the cell-adhesive modification of polytetrafluoroethylene

    International Nuclear Information System (INIS)

    Gabriel, Matthias; Dahm, Manfred; Vahl, Christian-F

    2011-01-01

    Polytetrafluoroethylene (PTFE), a frequently utilized polymer for the fabrication of synthetic vascular grafts, was surface-modified by means of a wet-chemical process. The inherently non-cell-adhesive polymer does not support cellular attachment, a prerequisite for the endothelialization of luminal surface grafts in small diameter applications. To impart the material with cell-adhesive properties a treatment with sodium-naphthalene provided a basis for the subsequent immobilization of the adhesion promoting RGD-peptide using a hydroxy- and amine-reactive crosslinker. Successful conjugation was shown with cell culture experiments which demonstrated excellent endothelial cell growth on the modified surfaces.

  19. Estudo da atividade do látex do Croton urucurana Baill. sobre o trânsito gastrintestinal de camundongos

    Directory of Open Access Journals (Sweden)

    Luilma Albuquerque Gurgel

    Full Text Available O presente trabalho tem como propósito avaliar uma possível atividade inibitória do látex do Croton urucurana Baill. sobre o trânsito gastrintestinal de camundongos, bem como tentar esclarecer os possíveis mecanismos de ação envolvidos em sua atividade. Foram utilizados os modelos de trânsito gastrintestinal normal e trânsito gastrintestinal estimulado por fisostigmina em camundongos. Os resultados obtidos mostram que o látex inibiu o trânsito gastrintestinal de camundongos, e, muito embora seu mecanismo de ação ainda não seja claro, seu efeito é independente da participação de mecanismo opióide, colinérgico, α2-adrenérgico ou nitriérgico.

  20. Purificación y caracterización preliminar de proteasas del látex de Vasconcellea candicans (A. Gray A. DC (Mito

    Directory of Open Access Journals (Sweden)

    Ana I. F. Gutiérrez

    2017-01-01

    Full Text Available E studios preliminares indican que , el látex fresco del “ M ito” tiene una actividad específica de papaína de 1,84 veces mayor a la encontrada en el látex of papaya, por lo que el objetivo de este trabajo fue purificar y caracterizar las proteasa s del látex fresco del “ M ito” que tuvieran actividad de papaína. El e xtracto crudo de proteasas se obtuvo a partir del látex de “Mito” el cual fue resuspendido (1:1 en buffer acetato de Na 10 mM a pH 5,0; inmediatamente se precipitaron proteínas a pH 9,0 y luego con sulfato de amonio al 45%. Posteriormente se purific ó en una columna de Sephadex G - 100 y se obtuvieron tres fracciones: A, B y C ; u tilizando como sustrato caseína se midió la actividad enzimática específica (AEE . S e encontró que para la Fracción A la AE E fue de 87,74 nkat.mg - 1 proteína, para la Fracción B fue de 14,93 nkat.mg - 1 proteína y para la Fracción C fue de 16,13 nkat.mg - 1 proteína . La AEE de la fracción A frente a la de papaína de látex fresco de C. papaya fue 13,3 veces mayor. En el análisis electrofor é tico (gel desnaturalizante , 12% se observa para la fracción A dos bandas de proteínas teniendo una de ellas una “ relación de frente ” semejante al estándar de papaína. Además, se observó que la fracción A (papaína de “Mito” frente a diferentes concentraciones de caseína, usada como sustrato, presenta una curva sigmoidea michaeliana; a diferentes volúmenes de enzima se muestra un comportamiento lineal; tiene un pH óptimo a 7,5 y es activa hasta 60 ºC .

  1. Radiation-induced branching and crosslinking of poly(tetrafluoroethylene) (PTFE)

    International Nuclear Information System (INIS)

    Lappan, U.; Geissler, U.; Haeussler, L.; Jehnichen, D.; Pompe, G.; Lunkwitz, K.

    2001-01-01

    The effect of electron beams on poly(tetrafluoroethylene) (PTFE) at elevated temperatures above the melting point on oxygen-free conditions has been studied using differential scanning calorimetry (DSC), wide-angle X-ray scattering (WAXS), Fourier-transform infrared (FTIR) spectroscopy, thermo-gravimetric analysis (TGA) and tensile test. The investigations have shown that the chemical structure and several properties of PTFE are greatly altered by the irradiation. DSC and WAXS indicate that the crystallinity of the PTFE irradiated with high doses is reduced. CF 3 side groups and branched structures are assumed to hinder the crystallization. TGA has shown that the thermal stability of the radiation-modified PTFE is considerably lower than that of unirradiated PTFE

  2. Poly-electrolyte fuel cell membrane based on crosslinked polytetrafluoroethylene by radiation-grafting

    International Nuclear Information System (INIS)

    Ichizuri, Shogo; Asano, Saneto; Li, Jingye

    2004-01-01

    Poly-electrolyte fuel cell (PEFC) membranes based on crosslinked Polytetrafluoroethylene (RX-PTFE) have been fabricated by radiation-grafting with reactive styrene monomers using γ-ray irradiation in air at room temperature / electron beam irradiation under N 2 gas atmosphere at room temperature. The characteristic properties of obtained materials have been measured by DSC, TGA and FT-IR spectroscopy, and so on. Ion exchange capacity of sulfonated crosslinked PTFE has been achieved 2.8meq/g. (author)

  3. FRHAM-TEX trademark cool suit - OST reference No. 1854. Deactivation and decommissioning focus area

    International Nuclear Information System (INIS)

    1998-02-01

    This paper describes a demonstration project for the FRHAM-TEX Cool Suit trademark manufactured by FRHAM Safety Products. It is a one-piece, disposable, breathable, waterproof coverall designed to permit moisture generated by the wearer to be transmitted outside the suit. The performance of this suit was compared to a Tyvek reg-sign suit as a baseline. The suit is proposed as safety ware for workers at decontamination and decommissioning projects

  4. Legionella dumoffii Tex-KL Mutated in an Operon Homologous to traC-traD is Defective in Epithelial Cell Invasion.

    Science.gov (United States)

    Qin, Tian; Ken-Ichiro, Iida; Ren, Hong Yu; Zhou, Hai Jian; Yoshida, Shin-Ichi

    2016-06-01

    To understand the mechanism of invasion by Legionella dumoffii. The L. dumoffii strain Tex-KL was mutated using the Tn903 derivative, Tn903dIIlacZ. After screening 799 transposon insertion mutants, we isolated one defective mutant. We then constructed the gene-disrupted mutant, KL16, and studied its invasion of and intracellular growth in HeLa and A549 cells, and in A/J mice survival experiments. The structure of traC-traD operon was analyzed by RT-PCR. The transposon insertion was in a gene homologous to Salmonella typhi traC, which is required for the assembly of F pilin into the mature F pilus structure and for conjugal DNA transmission. Results from RT-PCR suggested that the traC-traD region formed an operon. We found that when the traC gene was disrupted, invasion and intracellular growth of L. dumoffii Tex-KL were impaired in human epithelial cells. When mice were infected by intranasal inoculation with a traC deficient mutant, their survival significantly increased when compared to mice infected with the wild-type strain.. Our results indicated that the traC-traD operon is required for the invasion and intracellular growth abilities of L. dumoffii Tex-KL in epithelial cells. Copyright © 2016 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

  5. Cold crystallization of polytetrafluoroethylene by γ irradiation

    International Nuclear Information System (INIS)

    Takenaga, M.; Yamagata, K.

    1980-01-01

    Changes in density and in the corresponding degree of crystallinity with radiation dose are studied experimentally for γ-irradiated polytetrafluoroethylene (PTFE) in the dose range from 1 x 10 3 to 1 x 10 9 R. The relation between the amorphous fraction and the radiation dose is derived from a quantitative analysis of cold crystallization by scission of polymer backbone chains. The characteristic radiation dose, at which one break occurs on the average per initial molecule, is estimated as about 3 x 10 4 R on the basis of a derived kinetic equation. The theoretical relation is modified by considering microvoids produced in the irradiated samples. The radii of microvoids in the form of spheres are evaluated as about 0.2 nm, and are also related to cage spheres relevant to the chain scission process. Good agreement between the modified theoretical relation and experimental data is attained over the entire range of radiation dose. 4 figures, 1 table

  6. Short- and long-term results of chordal reconstruction using artificial suture material (polytetrafluoroethylene and polypropylene in the dog

    Directory of Open Access Journals (Sweden)

    Isamu Kanemoto

    2017-04-01

    Full Text Available No previous reports have compared the suitability of expanded polytetrafluoroethylene (ePTFE and polypropylene as artificial suture materials for chordal reconstruction in mitral valve plasty (MVP in the dog. Twelve normal dogs were subjected to MVP using surfaceinduced deep hypothermia. In the short-term group (1.5-4 months after surgery, all ePTFE sutures were covered by a tissue sheath including the paired suture arms, which gave the appearance of native chordae from 2 months after surgery. In contrast, all polypropylene sutures were not covered by tissue, and appeared the same as the paired polypropylene suture arms at the operation. In the long-term group (12 months after surgery, all ePTFE sutures were covered by a tissue sheath, which appeared the same as that in the short-term group, and had flexibility without increased thickness with time. In contrast, although the polypropylene suture was covered completely by a tissue sheath in 1 dog, all the other polypropylene sutures were exposed except for both ends of the suture. ePTFE may be superior to polypropylene as an artificial suture material for chordal reconstruction in MVP.

  7. 33 CFR 208.19 - Marshall Ford Dam and Reservoir (Mansfield Dam and Lake Travis), Colorado River, Tex.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Marshall Ford Dam and Reservoir... Marshall Ford Dam and Reservoir (Mansfield Dam and Lake Travis), Colorado River, Tex. The Secretary of the Interior, through his agent, the Lower Colorado River Authority (LCRA) shall operate the Marshall Ford Dam...

  8. Growth properties of poly(tetrafluoroethylene) films by synchrotron radiation ablation

    International Nuclear Information System (INIS)

    Guo, Qixin; Kugino, Takashi; Kume, Yusuke; Mitsuishi, Yoshiaki; Tanaka, Tooru; Nishi, Mitsuhiro; Ogawa, Hiroshi

    2007-01-01

    High-quality poly(tetrafluoroethylene) (PTFE) films have been grown on Si substrates by synchrotron radiation ablation of a PTFE target. Only doublet absorption structures assigned to C-F asymmetric and symmetric stretching vibrations in CF 2 groups are observed, suggesting that the CF 2 groups in the grown PTFE film are organized in an ordered manner through linear attachment. The growth rate of the PTFE films increases with increasing target temperature, while it decreases with increasing substrate temperature. It has been shown that the thickness of the PTFE film with a high-spatial-resolution structure can be easily controlled at nanometer order by changing the synchrotron radiation irradiation dose. (author)

  9. Demonstration of the AGI Universal Samplers (F.K.A. the GORE (registered trademark) Modules) for Passive Sampling of Groundwater

    Science.gov (United States)

    2014-03-01

    and lower Hen- ry’s Law constants are biased low (Anderson 2013). In this instance, me- thyl tert-butyl ether (MTBE) is lost entirely and 1,2...coolers full of ice or blue ice to transport samples to the laboratory. One limitation associated with using the GORE Module is that, like all no- purge...was taken from Dunbar et al. (2001). A regional geologic and geomorphic model was developed for the Aberdeen Prov- ing Ground (APG). Regional

  10. The effect of normal load on polytetrafluoroethylene tribology.

    Science.gov (United States)

    Barry, Peter R; Chiu, Patrick Y; Perry, Scott S; Sawyer, W Gregory; Phillpot, Simon R; Sinnott, Susan B

    2009-04-08

    The tribological behavior of oriented poly(tetrafluoroethylene) (PTFE) sliding surfaces is examined as a function of sliding direction and applied normal load in classical molecular dynamics (MD) simulations. The forces are calculated with the second-generation reactive empirical bond-order potential for short-range interactions, and with a Lennard-Jones potential for long-range interactions. The range of applied normal loads considered is 5-30 nN. The displacement of interfacial atoms from their initial positions during sliding is found to vary by a factor of seven, depending on the relative orientation of the sliding chains. However, within each sliding configuration the magnitude of the interfacial atomic displacements exhibits little dependence on load over the range considered. The predicted friction coefficients are also found to vary with chain orientation and are in excellent quantitative agreement with experimental measurements.

  11. Reação anafilática durante transplante renal intervivos em criança alérgica ao látex: relato de caso Reacción anafiláctica durante transplante renal intervivos en niño alérgico al látex: relato de caso Anaphylaxis during renal transplantation of live donor graft in a child with latex allergy: case report

    Directory of Open Access Journals (Sweden)

    Glória Maria Braga Potério

    2009-04-01

    Full Text Available JUSTIFICATIVA E OBJETIVOS: A alergia ao látex vem se tornando frequente, atingindo pacientes e profissionais de saúde. O objetivo deste relato foi apresentar um caso de criança alérgica ao látex que desenvolveu crise anafilática durante anestesia para transplante renal e destacar algumas condutas multiprofissionais empregadas para diminuir o risco de choque anafilático após a reperfusão do transplante. RELATO DO CASO: Criança do sexo masculino, com 5 anos e 10 meses, P3 pela classificação da ASA, com história de alergia ao látex, diagnosticada após contato com bexigas de festa e confirmada por testes Rast específico para o látex e Prick teste, foi submetida a transplante renal intervivos, por insuficiência renal terminal em consequência de malformação urológica. Os cuidados para evitar a exposição da criança ao látex seguiram os protocolos para paciente alérgico ao látex, adotados pelo Serviço de Anestesia e de Enfermagem do Hospital das Clínicas da UNICAMP. Foram iniciados na véspera da operação com a limpeza terminal das salas cirúrgicas e a substituição de todos os produtos médico-hospitalares por produtos isentos de látex. Os equipamentos e materiais utilizados durante o procedimento possuíam laudo técnico de isenção completa de látex, fornecido pelo fabricante. A operação foi realizada sob anestesia geral com ventilação controlada mecânica. Ao final da operação necessitou de transfusão de concentrado de hemácias administrado com auxílio de pressurizador, apresentando rash cutâneo, cessou-se a transfusão, administrou-se hidrocortisona e aumentou-se a infusão de cristaloides. A resposta ao tratamento foi satisfatória e imediata. CONCLUSÕES: A alergia ao látex tornou-se um problema de saúde pública e o conhecimento de condutas terapêuticas específicas possibilita o pronto atendimento e menor risco para os pacientesJUSTIFICATIVA Y OBJETIVOS: La alergia al látex ha venido alcanzando

  12. Vena cava superior syndrome associated with sarcoidosis

    International Nuclear Information System (INIS)

    Wurm, K.; Walz, M.; Reidemeister, J.C.; Donhuijsen, K.

    1988-01-01

    We report the first observation of clinical manifestations of vena cava superior syndrome (VCSS) associated with sarcoidosis. Twenty-four years after the first signs of the disease had been noted, mediastinal lymphomas penetrating the wall of the vena cava superior caused complete obstruction. It is most unusual for the vessel wall to be destroyed in this way, which explains why VCSS is often missed in sarcoidosis. The obstructed vessel was resected and successfully replaced by a Gore-Tex prosthesis. The importance of VCSS for the differential diagnosis is pointed out. Two further peculiarities are the simultaneous occurrence of elevated intraocular pressure and VCSS, and the familial incidence. (orig.) [de

  13. Leiomyosarcoma of inferior vena cava involving bilateral renal veins: Surgical challenges and reconstruction with upfront saphenous vein interposition graft for left renal vein outflow

    Directory of Open Access Journals (Sweden)

    Rishi Nayyar

    2010-01-01

    Full Text Available Leiomyosarcoma of inferior vena cava (IVC involving bilateral renal veins presents a surgical challenge. Herein, we report the successful management of two such cases using restoration of left renal venous outflow by saphenous vein interposition graft as first step of surgery. Then radical resection of tumor and right kidney was done. IVC was lastly reconstructed using Gore-Tex graft. This report highlights the surgical challenges to ensure radical resection. Furthermore, the importance of restoring left renal outflow in presence of concomitant right nephrectomy is discussed. Both the patients were disease free at six months with no loss of left renal glomerular filtration rate.

  14. A new concept for very low energy detonators and torches

    Energy Technology Data Exchange (ETDEWEB)

    Bickes, Jr., R. W.; Grubelich, M. C.; Romero, J. A.; Staley, D. J.; Buss, R. J.; Ward, P. P.; Erickson, K. L.

    1996-03-01

    We deposited secondary explosive and multilayer thermite films directly onto semiconductor bridges (SCBs) and other substrates. Methods for the deposition of two thermite films (aluminum/copper oxide and magnesium/fluorocarbon polymer) were developed as part of this study and a new capability was obtained for depositing adherent films on any material, including Teflon and Gore-Tex. Our experimental program determined conditions for the SCB ignition of the deposited films, and with the aluminum/copper oxide film, we observed a lower threshold for ignition of a powder pressed against the bridge. We also looked at other ignition methods including lasers, spark discharges, primers and hot combustion gases.

  15. Total Artificial Heart as Rescue Therapy for Primary Graft Failure in an Infant.

    Science.gov (United States)

    Ziegler, Luke A; Sainathan, Sandeep; Morell, Victor O; Sharma, Mahesh S

    2018-04-01

    An infant unable to be weaned from cardiopulmonary bypass after orthotopic heart transplantation was cannulated for extracorporeal membrane oxygenation. During the next 3 days, allograft failure and intracardiac thrombosis necessitated cardiectomy. To provide acute mechanical circulatory support, artificial atrial chambers were constructed with Gore-Tex conduits and PediMag centrifugal pumps were connected to each by Berlin Heart EXCOR cannulae. The PediMag pumps were subsequently exchanged for 10-mL Berlin Heart EXCOR pumps. After 60 days of support by total artificial heart, the patient was bridged successfully to a second heart transplant. Copyright © 2018 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  16. Comparative study of the monomer grafting: ethylene, acetylene, 1,3-butadiene and estyrene in the matrix of recycled polytetrafluoroethylene (PTFE)

    International Nuclear Information System (INIS)

    Ikari, Carolina T.; Rosner, Gerhardyne O.; Oliveira, Ana C.F.; Ferreto, Helio F.R.; Lima, Luiz F.C.P.; Lugao, Ademar B.; Moreira, Otavio M.

    2009-01-01

    In this study it is used the recycled polytetrafluoroethylene (PTFE), that with the gamma radiation under inert atmosphere or in presence of air, it is obtained free radicals and a posterior the monomer grafting (ethylene, acetylene, styrene or 1.3 butadiene), obtaining the copolymer polytetrafluoroethylene-g-monomer. It is studied the obtention of the polymer by two methods: by direct way, via grafting, where the polymer is irradiated in presence of monomer, and via grafting when the polymer is irradiated in absence of monomer and under inert or air. The characterization of the copolymer was performed by the techniques of infrared region absorption spectroscopy with Fourier transformation (FTIR), thermogravimetric (TGA) and derivative thermogravimetry (DTG), and percentage of mass grafting (DOG)

  17. Diseño del sistema de automatización de la fabricación de pinturas y del sistema para la transferencia fiscal del látex en la fábrica pintec, de Guayaquil

    OpenAIRE

    Espol; Salazar Aguirre, Jorge Patricio

    2016-01-01

    Se analizó el proceso de fabricación de pinturas. Se identificaron las deficiencias y se hicieron las propuestas de mejoras. Las propuestas de mejoras se realizaron en dos áreas: área de almacenamiento de látex y área de fabricación de pinturas. Se propuso mejorar el control del inventario y transferencia de látex desde los camiones de transporte de látex y controlar con exactitud el llenado de los tanques de preparación de pinturas según las recetas establecidas para la fabricación, así como...

  18. Alergia al látex en los trabajadores sanitarios (I: Vigilancia de la salud

    Directory of Open Access Journals (Sweden)

    María Soledad Gil Micharet

    2007-09-01

    Full Text Available La alergia al látex constituye un importante problema de salud entre los trabajadores sanitarios, tanto por su elevada prevalencia como por la gravedad de las reacciones que puede producir. La detección temprana de los síntomas mediante una vigilancia de la salud específica, y las medidas encaminadas a evitar la sensibilización y a prevenir la aparición de sintomatología y la progresión de la enfermedad en los trabajadores ya sensibilizados, son las mejores estrategias de intervención sobre este problema ocupacional. El artículo, realiza en esta primera parte, una revisión de la epidemiología, clínica y diagnóstico, y propone un protocolo médico específico.Látex allergy constitutes an important problem of health in the healthcare workers, so much for its high prevalence as for the graveness of the reactions that can take place. The early detection of the symptoms by means of specific health surveillance, and the measures guided to avoid the sensitization and to prevent the symptomatology appearance and progression of the illness in the sensitized workers, are the best intervention strategies on this occupational problem. The article carries out in this first part, a revision of the epidemiology, clinic and diagnosis, and it proposes a specific medical protocol.

  19. TRATAMIENTOS PARA REDUCIR LOS DAÑOS POR LÁTEX EN MANGO (Mangifera indica)

    OpenAIRE

    Marta Montero; Manuel Enrique Molina

    2005-01-01

    El objetivo de este estudio fue evaluar tratamientos alternativos para reducir las manchas de látex en mango. Se utilizaron frutos del cultivar Amarilla y soluciones (1% en agua) de eter lauril sulfonato de sodio (ELSS), ácido sulfónico (AS), amida de coco (AC) y nonil fenol etoxilado (NFE); hipoclorito de sodio (100 y 200 mg l-1 en agua); agua; con 3 tratamientos testigo (deslechado en seco y manchado intencional con limpieza posterior y sin ella). Se midió la incidencia y severidad de ...

  20. Recycling of Polytetrafluoroethylene Scarp for Useful Practical Applications

    International Nuclear Information System (INIS)

    El-Nemr, K.F.; Youssef, H.A.; Abd-El Aziz, M.M.; El-Miligy, A.A.

    1999-01-01

    Radiation vulcanization of NBR based composites were prepared whereby polytetrafluoroethylene, PTFE scrap was utilized as additive. The thermal property of composites, using TGA technique was investigated as a function of irradiation dose as well as the degree of loading with Teflon scarp. Moreover, the effect of gasoline solvent of varying content of toluene on the swelling characteristics of prepared composites has been followed up at 100 degree whereby, the irradiation dose was kept at 100 kGy. It was found that due to incorporation of PTFE powder , the solid composites obtained possess good thermal stability as well as swelling resistance. The best swelling resistance was obtained for the gasoline which does not contains toluene. The prepared rubber composites would be recommended for manufacturing rubber articles characterized by having self-lubricating property used as rubber seals under static condition, that may be at temperatures as high as 100 degree

  1. TeX4 (X = F, Cl, Br) as Lewis acids--complexes with soft thio- and seleno-ether ligands.

    Science.gov (United States)

    Hector, Andrew L; Jolleys, Andrew; Levason, William; Reid, Gillian

    2012-08-28

    TeF(4) reacts with OPR(3) (R = Me or Ph) in anhydrous CH(2)Cl(2) to give the colourless, square based pyramidal 1 : 1 complexes [TeF(4)(OPR(3))] only, in which the OPR(3) is coordinated basally in the solid state, (R = Me: d(Te-O) = 2.122(2) Å; R = Ph: d(Te-O) = 2.1849(14) Å). Variable temperature (19)F{(1)H}, (31)P{(1)H} and (125)Te{(1)H} NMR spectroscopic studies strongly suggest this is the low temperature structure in solution, although the systems are dynamic. The much softer donor ligands SMe(2) and SeMe(2) show a lower affinity for TeF(4), although unstable, yellow products with spectroscopic features consistent with [TeF(4)(EMe(2))] are obtained by the reaction of TeF(4) in neat SMe(2) or via reaction in CH(2)Cl(2) with SeMe(2). TeX(4) (X = F, Cl or Br) causes oxidation and halogenation of TeMe(2) to form X(2)TeMe(2). The Br(2)TeMe(2) hydrolyses in trace moisture to form [BrMe(2)Te-O-TeMe(2)Br], the crystal structure of which has been determined. TeX(4) (X = Cl or Br) react with the selenoethers SeMe(2), MeSe(CH(2))(3)SeMe or o-C(6)H(4)(SeMe)(2) (X = Cl) in anhydrous CH(2)Cl(2) to give the distorted octahedral monomers trans-[TeX(4)(SeMe(2))(2)], cis-[TeX(4){MeSe(CH(2))(3)SeMe}] and cis-[TeCl(4){o-C(6)H(4)(SeMe)(2)}], which have been characterised by IR, Raman and multinuclear NMR ((1)H, (77)Se{(1)H} and (125)Te{(1)H}) spectroscopy, and via X-ray structure determinations of representative examples. Tetrahydrothiophene (tht) can form both 1 : 1 and 1 : 2 Te : L complexes. For X = Br, the former has been shown to be a Br-bridged dimer, [Br(3)(tht)Te(μ-Br)(2)TeBr(3)(tht)], by crystallography with the tht ligands anti, whereas the latter are trans-octahedral monomers. Like its selenoether analogue, MeS(CH(2))(3)SMe forms distorted octahedral cis-chelates, [TeX(4){MeS(CH(2))(3)SMe}], whereas the more rigid o-C(6)H(4)(SMe)(2) unexpectedly forms a zig-zag chain polymer in the solid state, [TeCl(4){o-C(6)H(4)(SMe)(2)}](n), in which the dithioether adopts an

  2. Patent foramen ovale closure with GORE HELEX or CARDIOFORM Septal Occluder vs. antiplatelet therapy for reduction of recurrent stroke or new brain infarct in patients with prior cryptogenic stroke

    DEFF Research Database (Denmark)

    Kasner, Scott E; Thomassen, Lars; Søndergaard, Lars

    2017-01-01

    Rationale The utility of patent foramen ovale (PFO) closure for secondary prevention in patients with prior cryptogenic stroke is uncertain despite multiple randomized trials completed to date. Aims The Gore REDUCE Clinical Study (REDUCE) aims to establish superiority of patent foramen ovale...... with truly cryptogenic strokes. Medical therapy is limited to antiplatelet agents in both arms thereby reducing confounding. The trial should determine whether patent foramen ovale closure with the Gore septal occluders is safe and more effective than medical therapy alone for the prevention of recurrent...... closure in conjunction with antiplatelet therapy over antiplatelet therapy alone in reducing the risk of recurrent clinical ischemic stroke or new silent brain infarct in patients who have had a cryptogenic stroke. Methods and design This controlled, open-label trial randomized 664 subjects...

  3. Gore's Nobel May Bring Even More Attention on Campuses to Environmental Issues: Award for Combating Climate Change Implicitly Honors the Work of Academic Scientists

    Science.gov (United States)

    Byrne, Richard; Monastersky, Richard

    2007-01-01

    When the Norwegian Nobel Committee announced that the 2007 Nobel Peace Prize would be shared by Al Gore, the former U.S. vice president, and the Intergovernmental Panel on Climate Change, the award implicitly celebrated a third party--academic institutions. Much of the research on global warming has come from university scientists, and higher…

  4. Evaluación de las pruebas dot blot y aglutinación de látex para el diagnóstico de cisticercosis en Perú

    Directory of Open Access Journals (Sweden)

    Eduardo Miranda-Ulloa

    Full Text Available Con el objetivo de evaluar las pruebas dot blot y aglutinación de látex para la detección de cisticercosis humana con antígeno de líquido de cisticerco de Taenia solium, se usaron 125 sueros humanos, de los cuales 60 procedían de personas con cisticercosis confirmada por Western Blot, 45 de personas con otras enfermedades parasitarias y 20 de personas aparentemente sanas. La concentración óptima del antígeno para impregnar las tiras dot blot fue de 0,01 ug/uL, y para impregnar las partículas de látex fue de 0,092 ug/uL. Para la prueba dot blot se encontró una sensibilidad del 100% y especificidad del 87,7%; para la aglutinación de látex una sensibilidad del 93,3% y especificidad del 89,2%. Ambas pruebas podrían ser de utilidad y factibles de implementar como alternativas de diagnóstico serológico en laboratorios de áreas endémicas del Perú

  5. 77 FR 17121 - RailAmerica, Inc., Palm Beach Rail Holding, Inc., RailAmerica Transportation Corp., RailTex, Inc...

    Science.gov (United States)

    2012-03-23

    ...% of the Class A Common Units of TransRail, giving RailTex a 70% ownership interest in TransRail and control of W&C through TransRail. The MG Principals will retain the Class B Common Units of TransRail... DEPARTMENT OF TRANSPORTATION Surface Transportation Board [Docket No. FD 35605] RailAmerica, Inc...

  6. Expanded polytetrafluoroethylene graft fistula for chronic hemodialysis.

    Science.gov (United States)

    Tellis, V A; Kohlberg, W I; Bhat, D J; Driscoll, B; Veith, F J

    1979-01-01

    In a retrospective study of 66 PTFE arteriovenous fistulae and 71 BCH arteriovenous fistulae for dialysis access, PTFE had a higher patency rate than BCH at 12 months (62.4 versus 32.5%). PTFE was easier to work with and easier to handle in the face of infection. The lateral upper arm approach to placement of the PTFE graft is desirable in patients who have had multiple previous access procedures because this area is usually free from scarring, is distant from neurovascular structures, and provides a greater length of graft for needle punctures.

  7. Improvement of radiation resistance for polytetrafluoroethylene(PTFE) by radiation cross-linking

    International Nuclear Information System (INIS)

    Oshima, Akihiro; Tabata, Yoneho; Ikeda, Shigetoshi; Seguchi, Tadao.

    1996-01-01

    The crosslinked polytetrafluoroethylene(PTFE) was prepared by electron beams irradiation technique in the molten state at 340degC ± 3degC in inert gas atmosphere. The crosslinking density was changed by the irradiation dose. The radiation resistance of crosslinked PTFE was investigated on the mechanical properties after irradiation by γ-rays at room temperature under vacuum and in air. The dose at half value of elongation at break was about 1MGy for 500kGy-crosslinked PTFE, while the dose for non-crosslinked PTFE was only 3.5kGy. It was found that the radiation resistance of PTFE was extremely improved by crosslinking. (author)

  8. Chemical structure and physical properties of radiation-induced crosslinking of polytetrafluoroethylene

    International Nuclear Information System (INIS)

    Oshima, Akihiro; Ikeda, Shigetoshi; Katoh, Etsuko; Tabata, Yoneho

    2001-01-01

    The chemical structure and physical properties of polytetrafluoroethylene (PTFE) that has been crosslinked by radiation have been studied by various methods. It has been found that a Y-type crosslinking structure and a Y-type structure incorporating a double bond (modified Y-type) is formed in PTFE by radiation-crosslinking in the molten state. In addition, various types of double bond structures, excluding the crosslinking site, have been identified. The crosslinked PTFE has a good light transparency due to the loss of crystallites, whilst it retains the excellent properties of electrical insulation and heat resistance. The coefficient of abrasion and the permanent creep are also greatly improved by crosslinking

  9. The friction and wear of γ-irradiated polytetrafluoroethylene

    International Nuclear Information System (INIS)

    Briscoe, B.J.; Ni, Z.

    1984-01-01

    The exposure of polytetrafluoroethylene (PTFE) to γ radiation significantly reduces the molecular weight but below the gross softening temperature suppresses the overall molecular domain mobility. The shear modulus and creep resistance increase but the toughness is reduced. Data are presented to substantiate these trends and to interpret their influence on the friction and wear of γ-damaged PTFE. The sliding friction on smooth rigid counterfaces increases but the wear in this configuration is decreased. The rate of abrasion on rough rigid counterfaces is increased. There is also an improvement in the ultimate load-bearing capacity. All the changes produced are a function of the exposure but most of the effects are fully manifested by 20 Mrad. The general conclusion is that the extent of the molecular mobility or migration induced by mechanical stresses, imposed in both the interface and the bulk of the polymer, has a critical effect on the friction and wear processes. (Auth.)

  10. Fabrication of polymer-alloy based on polytetrafluoroethylene by radiation-crosslinking

    International Nuclear Information System (INIS)

    Oshima, A.; Asano, S.; Hyunga, T.; Ichizuri, S.; Washio, M.

    2003-01-01

    Perfluoropolymer such as polytetrafluoroethylene (PTFE), tetrafluoroethylene co-perfluoroalkylvinylether (PFA) and tetrafluoroethylene-co-hexafluoropropylene (FFP) have been classified to be a typical polymer of radiation-induced degradation. However, we confirmed that the crosslinking of PTFE, PFA and FEP proceed by irradiation under selective condition where oxygen-free and high temperature above the melting temperature of them. In this study, fabrication of polymer-alloy based on PTFE has been demonstrated by radiation-crosslinking techniques. The polymer alloy, which was PTFE fine powder contained with other polymeric materials, was obtained by electron beams irradiation under oxygen-free atmosphere. Characterization of polymer-alloy based on PTFE has been studied by various measurements such as solid state 19F- and 13C-NMR spectroscopy, thermal analysis (DSC, TGA)

  11. High spatial and spectral resolution measurements of Jupiter's auroral regions using Gemini-North-TEXES

    Science.gov (United States)

    Sinclair, J. A.; Orton, G. S.; Greathouse, T. K.; Lacy, J.; Giles, R.; Fletcher, L. N.; Vogt, M.; Irwin, P. G.

    2017-12-01

    Jupiter exhibits auroral emission at a multitude of wavelengths. Auroral emission at X-ray, ultraviolet and near-infrared wavelengths demonstrate the precipitation of ion and electrons in Jupiter's upper atmosphere, at altitudes exceeding 250 km above the 1-bar level. Enhanced mid-infrared emission of CH4, C2H2, C2H4 and further hydrocarbons is also observed coincident with Jupiter's auroral regions. Retrieval analyses of infrared spectra from IRTF-TEXES (Texas Echelon Cross Echelle Spectrograph on NASA's Infrared Telescope Facility) indicate strong heating at the 1-mbar level and evidence of ion-neutral chemistry, which enriches the abundances of unsaturated hydrocarbons (Sinclair et al., 2017b, doi:10.1002/2017GL073529, Sinclair et al., 2017c (under review)). The extent to which these phenomena in the stratosphere are correlated and coupled physically with the shorter-wavelength auroral emission originating from higher altitudes has been a challenge due to the limited spatial resolution available on the IRTF. Smaller-scale features observed in the near-infrared and ultraviolet emission, such as the main `oval', transient `swirls' and dusk-active regions within the main oval (e.g. Stallard et al., 2014, doi:10.1016/j/Icarus.2015.12.044, Nichols et al., 2017, doi: 10.1002/2017GL073029) are potentially being blurred in the mid-infrared by the diffraction-limited resolution (0.7") of IRTF's 3-metre primary aperture. However, on March 17-19th 2017, we obtained spectral measurements of H2 S(1), CH4, C2H2, C2H4 and C2H6 emission of Jupiter's high latitudes using TEXES on Gemini-North, which has a 8-metre primary aperture. This rare opportunity combines the superior spectral resolving power of TEXES and the high spatial resolution provided by Gemini-North's 8-metre aperture. We will perform a retrieval analyses to determine the 3D distributions of temperature, C2H2, C2H4 and C2H6. The morphology will be compared with near-contemporaneous measurements of H3+ emission from

  12. High-rate anisotropic ablation and deposition of polytetrafluoroethylene using synchrotron radiation process

    International Nuclear Information System (INIS)

    Inayoshi, Muneto; Ikeda, Masanobu; Hori, Masaru; Goto, Toshio; Hiramatsu, Mineo; Hiraya, Atsunari.

    1995-01-01

    Both anisotropic ablation and thin film formation of polytetrafluoroethylene (PTFE) were successfully demonstrated using synchrotron radiation (SR) irradiation of PTFE, that is, the SR ablation process. Anisotropic ablation by the SR irradiation was performed at an extremely high rate of 3500 μm/min at a PTFE target temperature of 200degC. Moreover, a PTFE thin film was formed at a high rate of 2.6 μm/min using SR ablation of PTFE. The chemical structure of the deposited film was similar to that of the PTFE target as determined from Fourier transform infrared absorption spectroscopy (FT-IR) analysis. (author)

  13. X-ray photoelectron spectroscopy study of synchrotron radiation irradiation of a polytetrafluoroethylene surface

    CERN Document Server

    Haruyama, Y; Matsui, S; Ideta, T; Ishigaki, H

    2003-01-01

    The effect of synchrotron radiation (SR) irradiation of a polytetrafluoroethylene (PTFE) surface was investigated using X-ray photoelectron spectroscopy (XPS). After the SR irradiation, the relative intensity of the F ls peak to the C ls peak decreased markedly. The chemical composition ratio to the F atoms to C atoms was estimated to be 0.29. From the curve fitting analysis of C ls and F ls XPS spectra, the chemical components and their intensity ratio were determined. The reason for the chemical composition change by the SR irradiation was discussed. (author)

  14. Reversible amorphous-crystalline phase changes in a wide range of Se1-xTex alloys studied using ultrafast differential scanning calorimetry

    NARCIS (Netherlands)

    Vermeulen, Paul. A.; Momand, Jamo; Kooi, Bart J.

    The reversible amorphous-crystalline phase change in a chalcogenide material, specifically the Se1-xTex alloy, has been investigated for the first time using ultrafast differential scanning calorimetry. Heating rates and cooling rates up to 5000 K/s were used. Repeated reversible

  15. Antibiotic bonding to polytetrafluoroethylene with tridodecylmethylammonium chloride

    International Nuclear Information System (INIS)

    Harvey, R.A.; Alcid, D.V.; Greco, R.S.

    1982-01-01

    Polytetrafluoroethylene (PTFE) treated with the cationic surfactant, triodecylmethylammonium chloride (TDMAC), binds 14 C-penicillin (1.5 to 2 mg antibiotic/cm graft), whereas untreated PTFE or PTFE treated with anionic detergents shows little binding of antibiotic. TDMAC-treated PTFE concomitantly binds penicillin and heparin, generating a surface that potentially can resist both infection and thrombosis. The retention of these biologically active molecules is not due to passive entrapment in the PTFE but reflects an ionic interaction between the anionic ligands and surface-bound TDMAC. Penicillin bound to PTFE is not removed by exhaustive washing in aqueous buffers but is slowly released in the presence of plasma or when the PTFE is placed in a muscle pouch in the rat. Muscle tissue adjacent to the treated PTFE shows elevated levels of antibiotic following implantation. PTFE treated with TDMAC and placed in a muscle pouch binds 14 C-penicillin when it is locally irrigated with antibiotic or when penicillin is administered intravenously. Thus, the TDMAC surface treated either in vitro or in vivo with penicillin provides an effective in situ source for the timed release of antibiotic

  16. Guided tissue regeneration ensures osseointegration of dental implants placed into extraction sockets. An experimental study in monkeys

    DEFF Research Database (Denmark)

    Warrer, L; Gotfredsen, K; Hjørting-Hansen, E

    1991-01-01

    on the buccal and palatal aspects of the maxillary molars in both sides of the jaw. The second molars were then extracted and self tapping titanium implants of the screw type (Astra Dental Implants) were inserted into the sockets of the largest roots. In the coronal portion of the sockets, a void was always...... present between the implant and the socket walls. In one side of the jaw, a membrane (Gore-Tex Augmentation Material) was adjusted to cover the implant. The implant in the other side of the jaw served as control and was only covered by the tissue flaps. Microscopic analysis after 3 months of healing...... technique can secure complete osseointegration of implants inserted immediately into extraction sockets....

  17. A Fast Placement Technique for Covered Tracheobronchial Stents in Patients with Complicated Esophagorespiratory Fistulas

    International Nuclear Information System (INIS)

    Kishi, Kazushi; Nakao, Taisei; Goto, Hironobu; Kimura, Masashi; Sonomura, Tetsuo; Yamanaka, Noboru; Nanjo, Kishio; Sato, Morio

    2005-01-01

    Purpose. To test an endotracheal placement procedure for malignant esophagorespiratory fistula when endoesophageal placement is inapplicable. Methods. We report on patients with malignant esophagorespiratory fistula to which endoesophageal approaches were complicated with a complete obstruction of the hypopharynx, a collapsible tracheobronchus, or a previously placed endoesophageal stents. Gore-Tex membrane-covered Z-stents were deployed in the trachea using a coaxial introducer system in three patients. A Dumon tube was deployed in the bronchus over the bronchofiberscope in one patient. Results. All fistula were completely sealed by the endotracheal or endobronchial stenting. Symptomatic and clinical improvements were immediate obtained. Conclusion. Endotracheal or endobronchial covered stent placement is thought to be an effective alternative method for sealing esophagorespiratory fistula

  18. Structural surprises in friction-deposited films of poly(tetrafluoroethylene)

    DEFF Research Database (Denmark)

    Breiby, Dag Werner; Sølling, Theis Ivan; Bunk, Oliver

    2005-01-01

    Thin films of poly(tetrafluoroethylene) (PTFE) produced by friction deposition were studied using grazing incidence X-ray diffraction as the principal tool. The structure of the deposited thin films was compared with that of the surface of the PTFE bar used for depositing the films. Both exhibited...... the 15/7 helix conformation characteristic of crystal PTFE phase IV. A high degree of biaxial orientation was found for the highly crystalline thin films. Whereas the unit cell of the bar surface material appeared to be single-stem hexagonal, the film displayed diffraction characteristics consistent...... the possibility of a continuous transition between the low-order single-stem hexagonal and the multistem high-order unit cell. The degree of chain orientation was much lower at the surface of the bar than in the thin film. A modification of the commonly accepted mechanism for the transfer of material from the bar...

  19. Reflectance dependence of polytetrafluoroethylene on thickness for xenon scintillation light

    Energy Technology Data Exchange (ETDEWEB)

    Haefner, J.; Neff, A.; Arthurs, M.; Batista, E.; Morton, D.; Okunawo, M.; Pushkin, K.; Sander, A. [Randall Laboratory of Physics, University of Michigan, Ann Arbor, MI 48109-1040 (United States); Stephenson, S. [Randall Laboratory of Physics, University of Michigan, Ann Arbor, MI 48109-1040 (United States); University of California Davis, Department of Physics, One Shields Ave., Davis, CA 95616 (United States); Wang, Y. [Randall Laboratory of Physics, University of Michigan, Ann Arbor, MI 48109-1040 (United States); Lorenzon, W., E-mail: lorenzon@umich.edu [Randall Laboratory of Physics, University of Michigan, Ann Arbor, MI 48109-1040 (United States)

    2017-06-01

    Many rare event searches including dark matter direct detection and neutrinoless double beta decay experiments take advantage of the high VUV reflective surfaces made from polytetrafluoroethylene (PTFE) reflector materials to achieve high light collection efficiency in their detectors. As the detectors have grown in size over the past decade, there has also been an increased need for ever thinner detector walls without significant loss in reflectance to reduce dead volumes around active noble liquids, outgassing, and potential backgrounds. We report on the experimental results to measure the dependence of the reflectance on thickness of two PTFE samples at wavelengths near 178 nm. No change in reflectance was observed as the wall thickness of a cylindrically shaped PTFE vessel immersed in liquid xenon was varied between 1 mm to 9.5 mm.

  20. Preparing polymer brushes on polytetrafluoroethylene films by free radical polymerization

    International Nuclear Information System (INIS)

    Sun Wei; Chen Yiwang; Deng Qilan; Chen Lie; Zhou Lang

    2006-01-01

    Films of polytetrafluoroethylene (PTFE) were exposed to sodium naphthalenide (Na/naphtha) etchant so as to defluorinate the surface for obtaining hydroxyl functionality. Surface-initiators were immobilized on the PTFE films by esterification of 4,4'-azobis(4-cyanopentanoic acid) (ACP) and the hydroxyl groups covalently linked to the surface. Grafting of polymer brushes on the PTFE films was carried out by the surface-initiated free radical polymerization. Homopolymers brushes of methyl methacrylate (MMA) were prepared by free radical polymerization from the azo-functionalized PTFE surface. The chemical composition and topography of the graft-functionalized PTFE surfaces were characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance (ATR) FT-IR spectroscopy and atomic force microscopy (AFM). Water contact angles on PTFE films were reduced by surface grafting of MMA

  1. Improvement of Meteorological Inputs for TexAQS-II Air Quality Simulations

    Science.gov (United States)

    Ngan, F.; Byun, D.; Kim, H.; Cheng, F.; Kim, S.; Lee, D.

    2008-12-01

    An air quality forecasting system (UH-AQF) for Eastern Texas, which is in operation by the Institute for Multidimensional Air Quality Studies (IMAQS) at the University of Houston, uses the Fifth-Generation PSU/NCAR Mesoscale Model MM5 model as the meteorological driver for modeling air quality with the Community Multiscale Air Quality (CMAQ) model. While the forecasting system was successfully used for the planning and implementation of various measurement activities, evaluations of the forecasting results revealed a few systematic problems in the numerical simulations. From comparison with observations, we observe some times over-prediction of northerly winds caused by inaccurate synoptic inputs and other times too strong southerly winds caused by local sea breeze development. Discrepancies in maximum and minimum temperature are also seen for certain days. Precipitation events, as well as clouds, are simulated at the incorrect locations and times occasionally. Model simulatednrealistic thunderstorms are simulated, causing sometimes cause unrealistically strong outflows. To understand physical and chemical processes influencing air quality measures, a proper description of real world meteorological conditions is essential. The objective of this study is to generate better meteorological inputs than the AQF results to support the chemistry modeling. We utilized existing objective analysis and nudging tools in the MM5 system to develop the MUltiscale Nest-down Data Assimilation System (MUNDAS), which incorporates extensive meteorological observations available in the simulated domain for the retrospective simulation of the TexAQS-II period. With the re-simulated meteorological input, we are able to better predict ozone events during TexAQS-II period. In addition, base datasets in MM5 such as land use/land cover, vegetation fraction, soil type and sea surface temperature are updated by satellite data to represent the surface features more accurately. They are key

  2. GORE PRECLUDE MVP dura substitute applied as a nonwatertight "underlay" graft for craniotomies: product and technique evaluation.

    Science.gov (United States)

    Chappell, E Thomas; Pare, Laura; Salehpour, Mohammed; Mathews, Marlon; Middlehof, Charles

    2009-01-01

    While watertight closure of the dura is a long-standing tenet of cranial surgery, it is often not possible and sometimes unnecessary. Many graft materials with various attributes and drawbacks have been in use for many years. A novel synthetic dural graft material called GORE PRECLUDE MVP dura substitute (WL Gore & Associates, Inc, Flagstaff, Ariz) (henceforth called "MVP") is designed for use both in traditional watertight dural closure and as a dural "underlay" graft in a nonwatertight fashion. One surface of MVP is engineered to facilitate fibroblast in-growth so that its proximity to the underside of the dura will lead to rapid incorporation, whereas the other surface acts as a barrier to reduce tissue adhesion to the device. A series of 59 human subjects undergoing craniotomy and available for clinical and radiographic follow-up underwent nonwatertight underlay grafting of their durotomy with MVP. This is an assessment of the specific product and technique. No attempt is made to compare this to other products or techniques. The mean follow-up in this group was more than 4 months. All subjects have ultimately experienced excellent outcomes related to use of the graft implanted with the underlay technique. No complications occurred related directly to MVP, but the wound-related complication rate attributed to the underlay technique was higher than expected (17%). However, careful analysis found a high rate of risk factors for wound complications and determined that complications with the underlay technique could be avoided by assuring close approximation of the graft material to the underside of the dura. MVP can be used as an underlay graft in a nonwatertight fashion. However, if used over large voids (relaxed brain or large tumor bed), "tacking" or traditional watertight closure techniques should be used. The underlay application of MVP is best applied over the convexities and is particularly well-suited to duraplasty after hemicraniectomy.

  3. Photolithography of polytetrafluoroethylene for tailored adhesion

    International Nuclear Information System (INIS)

    Rye, R.R.; Martinez, R.J.

    1988-01-01

    Irradiation of polytetrafluoroethylene (PTFE) with Mg (Kα) x-rays is shown to protect the surface against the chemical etching steps used to prepare PTFE for adhesion. Pre-irradiated etched samples of PTFE have adhesions strengths of less than 3% of that for non-irradiated etched samples. The major portion of this decrease in adhesion strength occurs for x-ray exposures of less than 10 min ∼4.8 x10 3 mrads) and failure in every case occurs in PTFE and not in the bonded transition region. XPS measurements (20 angstrom sampling depth) show little difference in F content between irradiated and non-irradiated samples, but thermal desorption shows increasing fluorocarbon desorption with irradiation time. These results are consistent with the known radiation chemistry of PTFE. Irradiation produced free radicals lead to branching and/ or cross-linking, and a surface rich in low molecular weight fluorocarbons. The more rigid cross-linked surface is resistant to deep (10,000 angstrom chemical attack and the bond formed is with a surface rich in short chain flurocarbons. Both a thin boundary region and bonding to short chain species is expected to lead to weak adhesive bonding. Electron irradiation is shown to lead to protection against chemical etching comparable to that obtained with X-rays. With electrons one has the patterns with resolution limited by the beam diameter

  4. A bioactive metallurgical grade porous silicon-polytetrafluoroethylene sheet for guided bone regeneration applications.

    Science.gov (United States)

    Chadwick, E G; Clarkin, O M; Raghavendra, R; Tanner, D A

    2014-01-01

    The properties of porous silicon make it a promising material for a host of applications including drug delivery, molecular and cell-based biosensing, and tissue engineering. Porous silicon has previously shown its potential for the controlled release of pharmacological agents and in assisting bone healing. Hydroxyapatite, the principle constituent of bone, allows osteointegration in vivo, due to its chemical and physical similarities to bone. Synthetic hydroxyapatite is currently applied as a surface coating to medical devices and prosthetics, encouraging bone in-growth at their surface and improving osseointegration. This paper examines the potential for the use of an economically produced porous silicon particulate-polytetrafluoroethylene sheet for use as a guided bone regeneration device in periodontal and orthopaedic applications. The particulate sheet is comprised of a series of microparticles in a polytetrafluoroethylene matrix and is shown to produce a stable hydroxyapatite on its surface under simulated physiological conditions. The microstructure of the material is examined both before and after simulated body fluid experiments for a period of 1, 7, 14 and 30 days using Scanning Electron Microscopy. The composition is examined using a combination of Energy Dispersive X-ray Spectroscopy, Thin film X-ray diffraction, Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy and the uptake/release of constituents at the fluid-solid interface is explored using Inductively Coupled Plasma-Optical Emission Spectroscopy. Microstructural and compositional analysis reveals progressive growth of crystalline, 'bone-like' apatite on the surface of the material, indicating the likelihood of close bony apposition in vivo.

  5. Superhydrophobic and icephobic surfaces prepared by RF-sputtered polytetrafluoroethylene coatings

    International Nuclear Information System (INIS)

    Jafari, R.; Menini, R.; Farzaneh, M.

    2010-01-01

    A superhydrophobic and icephobic surface were investigated on aluminum alloy substrate. Anodizing was used first to create a micro-nanostructured aluminum oxide underlayer on the alloy substrate. In a second step, the rough surface was coated with RF-sputtered polytetrafluoroethylene (PTFE or Teflon). Scanning electron microscopy images showed a 'bird's nest'-like structure on the anodized surface. The RF-sputtered PTFE coating exhibited a high static contact angle of ∼165 deg. with a very low contact angle hysteresis of ∼3 deg. X-ray photoelectron spectroscopy (XPS) results showed high quantities of CF 3 and CF 2 groups, which are responsible for the hydrophobic behavior of the coatings. The performance of this superhydrophobic film was studied under atmospheric icing conditions. These results showed that on superhydrophobic surfaces ice-adhesion strength was 3.5 times lower than on the polished aluminum substrate.

  6. Superhydrophobic and icephobic surfaces prepared by RF-sputtered polytetrafluoroethylene coatings

    Science.gov (United States)

    Jafari, R.; Menini, R.; Farzaneh, M.

    2010-12-01

    A superhydrophobic and icephobic surface were investigated on aluminum alloy substrate. Anodizing was used first to create a micro-nanostructured aluminum oxide underlayer on the alloy substrate. In a second step, the rough surface was coated with RF-sputtered polytetrafluoroethylene (PTFE or Teflon ®). Scanning electron microscopy images showed a " bird's nest"-like structure on the anodized surface. The RF-sputtered PTFE coating exhibited a high static contact angle of ˜165° with a very low contact angle hysteresis of ˜3°. X-ray photoelectron spectroscopy (XPS) results showed high quantities of CF 3 and CF 2 groups, which are responsible for the hydrophobic behavior of the coatings. The performance of this superhydrophobic film was studied under atmospheric icing conditions. These results showed that on superhydrophobic surfaces ice-adhesion strength was 3.5 times lower than on the polished aluminum substrate.

  7. IMPROVED HEALING OF SMALL-CALIBER POLYTETRAFLUOROETHYLENE PROSTHESES BY INDUCTION OF A CLOT LAYER - A REVIEW OF EXPERIMENTAL STUDIES IN RATS

    NARCIS (Netherlands)

    VANDERLEI, B; STRONCK, JW; WILDEVUUR, CRH

    1991-01-01

    This report reviews our experiments that have been undertaken to test the hypothesis whether the induction of a clot layer on the graft surface of small-caliber polytetrafluoroethylene ( PTFE) prostheses might improve their healing. 1 2 PTFE prostheses with a fibril length of 30-mu-m, PTFE

  8. Avaliação dos elásticos ortodônticos intra-orais de látex e de borracha sintética: estudo in vitro e in vivo

    OpenAIRE

    Daniela Ferreira de Carvalho Notaroberto

    2014-01-01

    Os elásticos ortodônticos intermaxilares sintéticos vem sendo cada vez mais utilizados, sendo principalmente indicados para pacientes que apresentam hiper-sensibilidade ao látex. Afim de avaliar e comparar o comportamento de elásticos de látex e sintéticos quanto a perda de força ao longo do tempo, este estudo foi realizado tanto in vitro quanto in vivo. Para o estudo in vitro foram avaliados 15 elásticos de cada material, para cada tempo: 0, 1, 3, 12 e 24 horas. No estudo in vivo, pacientes ...

  9. Patent foramen ovale closure with GORE HELEX or CARDIOFORM Septal Occluder vs. antiplatelet therapy for reduction of recurrent stroke or new brain infarct in patients with prior cryptogenic stroke: Design of the randomized Gore REDUCE Clinical Study.

    Science.gov (United States)

    Kasner, Scott E; Thomassen, Lars; Søndergaard, Lars; Rhodes, John F; Larsen, Coby C; Jacobson, Joth

    2017-12-01

    Rationale The utility of patent foramen ovale (PFO) closure for secondary prevention in patients with prior cryptogenic stroke is uncertain despite multiple randomized trials completed to date. Aims The Gore REDUCE Clinical Study (REDUCE) aims to establish superiority of patent foramen ovale closure in conjunction with antiplatelet therapy over antiplatelet therapy alone in reducing the risk of recurrent clinical ischemic stroke or new silent brain infarct in patients who have had a cryptogenic stroke. Methods and design This controlled, open-label trial randomized 664 subjects with cryptogenic stroke at 63 multinational sites in a 2:1 ratio to either antiplatelet therapy plus patent foramen ovale closure (with GORE® HELEX® Septal Occluder or GORE® CARDIOFORM Septal Occluder) or antiplatelet therapy alone. Subjects will be prospectively followed for up to five years. Neuroimaging is required for all subjects at baseline and at two years or study exit. Study outcomes The two co-primary endpoints for the study are freedom from recurrent clinical ischemic stroke through at least 24 months post-randomization and incidence of new brain infarct (defined as clinical ischemic stroke or silent brain infarct) through 24 months. The primary analyses are an unadjusted log-rank test and a binomial test of subject-based proportions, respectively, both on the intent-to-treat population, with adjustment for testing multiplicity. Discussion The REDUCE trial aims to target a patient population with truly cryptogenic strokes. Medical therapy is limited to antiplatelet agents in both arms thereby reducing confounding. The trial should determine whether patent foramen ovale closure with the Gore septal occluders is safe and more effective than medical therapy alone for the prevention of recurrent clinical ischemic stroke or new silent brain infarct; the neuroimaging data will provide an opportunity to further support the proof of concept. The main results are anticipated in 2017

  10. Peritoneostomy with latex coated polypropylene: experimental study in rats Peritoniostomia com polipropileno revestido por látex: estudo experimental em ratos

    Directory of Open Access Journals (Sweden)

    Renato Hugues Atique Claudio

    2006-12-01

    Full Text Available PURPOSE: To evaluate if latex coated polypropylene mesh leads to less adhesions formation. METHODS: 90 rats were distributed in three groups. Group I (control was submitted to median laparotomy and posterior synthesis; Group II (polypropylene was submitted to a segment resection of the abdominal wall, and the defect was corrected with a polypropylene mesh; Group III using the new material (latex coated polypropylene. After 45 days the euthanasia procedure was done and the adhesions were evaluated in 2 ways: 1 classification in a grading system; 2 evaluation of the adhesion area, which was calculated by resection of the adhesions after dying with Indian blue ink. RESULTS: The classification in a grading system showed that Group III animals had less adhesions formation (P0.05. The severe complications (fistula, evisceration and obstruction, which were lethal, were not reduced by the latex coated material. CONCLUSION: Latex coated polypropylene causes fewer adhesion formations than polypropylene alone, although it does not diminish the severe early complications.OBJETIVO: Avaliar se o revestimento da tela de polipropileno com látex leva a menor formação de aderências. MÉTODOS: Foram utilizados 90 ratos, distribuídos em três grupos de 30: grupo I (controle animais submetidos a laparotomia mediana e posterior síntese; grupo II (polipropileno ressecção de segmento da parede abdominal e síntese com tela de polipropileno; grupo III, (polipropileno revestido por látex. Eutanásia foi realizada após 45 dias e as aderências avaliadas sob duas formas: 1 classificação em graus; 2 avaliação da área aderida, calculada corando-se o segmento da parede contendo as aderências que posteriormente foram ressecadas produzindo uma região clara em contraste com o restante da peça, corada. RESULTADOS: Na avaliação por meio de graus, o grupo III apresentou menor formação de aderências (p0,05. As complicações graves não foram reduzidas pelo

  11. Active screen cage pulsed dc discharge for implanting copper in polytetrafluoroethylene (PTFE)

    Science.gov (United States)

    Zaka-ul-Islam, Mujahid; Naeem, Muhammad; Shafiq, Muhammad; Sitara; Jabbar Al-Rajab, Abdul; Zakaullah, Muhammad

    2017-07-01

    Polymers such as polytetrafluoroethylene (PTFE) are widely used in artificial organs where long-term anti-bacterial properties are required to avoid bacterial proliferation. Copper or silver ion implantation on the polymer surface is known as a viable method to generate long-term anti-bacterial properties. Here, we have tested pulsed DC plasma with copper cathodic cage for the PTFE surface treatment. The surface analysis of the treated specimens suggests that the surface, structural properties, crystallinity and chemical structure of the PTFE have been changed, after the plasma treatment. The copper release tests show that copper ions are released from the polymer at a slow rate and quantity of the released copper increases with the plasma treatment time.

  12. Solution casting Nafion/polytetrafluoroethylene membrane for vanadium redox flow battery application

    International Nuclear Information System (INIS)

    Teng, Xiangguo; Sun, Cui; Dai, Jicui; Liu, Haiping; Su, Jing; Li, Faqiang

    2013-01-01

    Highlights: ► Nafion/polytetrafluoroethylene (PTFE) blend membranes were prepared by solution casting method. ► The blend membranes were tested for vanadium redox flow battery (VRB) application. ► The blend membranes show lower vanadium ion permeability than that of recast Nafion membrane. ► In VRB single cell test, the blend membrane shows superior performances than that of pure recast Nafion. -- Abstract: Solution casting method was adopted using Nafion and polytetrafluoroethylene (PTFE) solution to prepare Nafion/PTFE blend membranes for vanadium redox flow battery application. The physicochemical properties of the membranes were characterized by using water uptake, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermal analysis (TA). The electrochemical properties of the membranes were examined by using electrochemical impedance spectroscopy (EIS) and single cell test. Despite the high miscibility of PTFE with Nafion, the addition of hydrophobic PTFE reduces the water uptake, ion exchange capacity (IEC) and conductivity of blend membranes. But PTFE can increase the crystallinity, thermal stability of Nafion/PTFE membranes and reduce the vanadium permeability. The blend membrane with PTFE (30 wt%, N 0.7 P 0.3 ) was chosen and investigated for VRB single cell test. The energy efficiency of this VRB with N 0.7 P 0.3 membrane was 85.1% at current density of 50 mA cm −2 , which was superior to that of recast Nafion (r-Nafion) membrane (80.5%). Self-discharge test shows that the decay of open circuit potential of N 0.7 P 0.3 membrane is much lower than that of r-Nafion membrane. More than 50 cycles charge–discharge test proved that the N 0.7 P 0.3 membrane possesses high stability in long time running. Chemical stabilities of the chosen N 0.7 P 0.3 membrane are further proved by soaking the membrane for 3 weeks in highly oxidative V(V) solution. All results suggest that the addition of PTFE is a simple and effective way to

  13. Thermodynamic properties and transport coefficients of a two-temperature polytetrafluoroethylene vapor plasma for ablation-controlled discharge applications

    International Nuclear Information System (INIS)

    Wang, Haiyan; Qi, Haiyang; Wang, Weizong; Yan, Joseph D; Geng, Jinyue; Wu, Yaowu

    2017-01-01

    Ablation-controlled plasmas have been used in a range of technical applications where local thermodynamic equilibrium (LTE) is often violated near the wall due to the strong cooling effect caused by the ablation of wall materials. The thermodynamic and transport properties of ablated polytetrafluoroethylene (PTFE) vapor, which determine the flowing plasma behavior in such applications, are calculated based on a two-temperature model at atmospheric pressure. To our knowledge, no data for PTFE have been reported in the literature. The species composition and thermodynamic properties are numerically determined using the two-temperature Saha equation and the Guldberg–Waage equation according to van de Sanden et al ’s derivation. The transport coefficients, including viscosity, thermal conductivity and electrical conductivity, are calculated with the most recent collision interaction potentials using Devoto’s electron and heavy-particle decoupling approach but expanded to the third-order approximation (second-order for viscosity) in the frame of the Chapman–Enskog method. Results are computed for different degrees of thermal non-equilibrium, i.e. the ratio of electron to heavy-particle temperatures, from 1 to 10, with electron temperature ranging from 300 to 40 000 K. Plasma transport properties in the LTE state obtained from the present work are compared with existing published results and the causes for the discrepancy analyzed. The two-temperature plasma properties calculated in the present work enable the modeling of wall ablation-controlled plasma processes. (paper)

  14. Thermodynamic properties and transport coefficients of a two-temperature polytetrafluoroethylene vapor plasma for ablation-controlled discharge applications

    Science.gov (United States)

    Wang, Haiyan; Wang, Weizong; Yan, Joseph D.; Qi, Haiyang; Geng, Jinyue; Wu, Yaowu

    2017-10-01

    Ablation-controlled plasmas have been used in a range of technical applications where local thermodynamic equilibrium (LTE) is often violated near the wall due to the strong cooling effect caused by the ablation of wall materials. The thermodynamic and transport properties of ablated polytetrafluoroethylene (PTFE) vapor, which determine the flowing plasma behavior in such applications, are calculated based on a two-temperature model at atmospheric pressure. To our knowledge, no data for PTFE have been reported in the literature. The species composition and thermodynamic properties are numerically determined using the two-temperature Saha equation and the Guldberg-Waage equation according to van de Sanden et al’s derivation. The transport coefficients, including viscosity, thermal conductivity and electrical conductivity, are calculated with the most recent collision interaction potentials using Devoto’s electron and heavy-particle decoupling approach but expanded to the third-order approximation (second-order for viscosity) in the frame of the Chapman-Enskog method. Results are computed for different degrees of thermal non-equilibrium, i.e. the ratio of electron to heavy-particle temperatures, from 1 to 10, with electron temperature ranging from 300 to 40 000 K. Plasma transport properties in the LTE state obtained from the present work are compared with existing published results and the causes for the discrepancy analyzed. The two-temperature plasma properties calculated in the present work enable the modeling of wall ablation-controlled plasma processes.

  15. Usefulness of a balloon-expandable, covered stent for the transjugular intrahepatic portosystemic shunt

    Directory of Open Access Journals (Sweden)

    Rössle M

    2018-01-01

    Full Text Available The availability of polytetrafluoroethylene (PTFE covered, self-expandable nitinol stents in 2001 considerably improved the patency, response rates and survival of the transjugular intrahepatic portosystemic shunt (TIPS. Side effects of portosystemic shunting such as hepatic encephalopathy (HE and worsening of hepatic function, however, remained a problem. To reduce HE, underdilatation of nitinol stents has been practiced for many years. However, as shown recently, underdilatation was a flop since, due to their intrinsic memory, nitinol stents always expanded to reach their nominal diameter of 8 or 10 mm. To overcome this problem and to be able to perform permanent shunts with a smaller diameter of < 8 mm, we studied the usefulness of a balloon-expandable, covered, metallic stent which allowed adjustment to any diameter between 5 and 12 mm. Methods: 30 patients with cirrhosis and symptomatic portal hypertension were included. The mean Child-Pugh score was 8 ± 2.17 patients had refractory ascites, 9 patients variceal bleeding and four patients other indications for the TIPS. Results: The TIPS was successfully implanted in all patients within 69.6 ± 21.8 min. The shunt reduced the portosystemic pressure gradient by 57.5 ± 14.2% with a mean stent diameter of 7.4 ± 1.0 mm (5 -10.3 mm. During a mean follow-up of 330 ± 249 days, shunt revision was necessary in 5 patients (17%, four of them had insufficient response and received stent dilatation and one patient had stent misplacement requiring a parallel shunt. Three patients (10% developed HE. Conclusions: The covered, balloon-expandable stent could be placed accurately and allowed creation of adapted shunts with smaller diameters as usual. This resulted in a comparatively low rate of HE.

  16. Production of polytetrafluoroethylene by means of polymerization induced by gamma radiation

    International Nuclear Information System (INIS)

    Sugao, A.B.

    1986-01-01

    The process of polytetrafluoroethylene (PTFE) production, is studied. The TFE monomer was prepared by pyrolisis of clorodifluoromethane (R-22) and purified by low temperature fractional distillation. The bulk polymerization of tetrafluoroethylene (TFE) induced by gamma rays from a 185 TBq (5000 Ci) Co-60 source was studied at several temperatures (0 0 C, -23 0 C e -78 0 C). The purified monomer was introduced into stainless steel cylindres of 15 and 60 ml under vacuum. Glass cylindres of 10,50 and 700 ml were also used for irradiation at -78 0 C. The polymer was obtained as white agglomerated particles. The I.R. spectra of polymer samples were consistent with those of commercial PTFE. The melting points of samples were between 327 and 331 0 C. (Author) [pt

  17. Superhydrophobic and icephobic surfaces prepared by RF-sputtered polytetrafluoroethylene coatings

    Energy Technology Data Exchange (ETDEWEB)

    Jafari, R., E-mail: rjafari@uqac.ca [NSERC / Hydro-Quebec / UQAC Industrial Chair on Atmospheric Icing of Power Network Equipment (CIGELE) and Canada Research Chair on Engineering of Power Network Atmospheric Icing (INGIVRE), Universite du Quebec a Chicoutimi, Chicoutimi, QC (Canada); Menini, R.; Farzaneh, M. [NSERC / Hydro-Quebec / UQAC Industrial Chair on Atmospheric Icing of Power Network Equipment (CIGELE) and Canada Research Chair on Engineering of Power Network Atmospheric Icing (INGIVRE), Universite du Quebec a Chicoutimi, Chicoutimi, QC (Canada)

    2010-12-15

    A superhydrophobic and icephobic surface were investigated on aluminum alloy substrate. Anodizing was used first to create a micro-nanostructured aluminum oxide underlayer on the alloy substrate. In a second step, the rough surface was coated with RF-sputtered polytetrafluoroethylene (PTFE or Teflon). Scanning electron microscopy images showed a 'bird's nest'-like structure on the anodized surface. The RF-sputtered PTFE coating exhibited a high static contact angle of {approx}165 deg. with a very low contact angle hysteresis of {approx}3 deg. X-ray photoelectron spectroscopy (XPS) results showed high quantities of CF{sub 3} and CF{sub 2} groups, which are responsible for the hydrophobic behavior of the coatings. The performance of this superhydrophobic film was studied under atmospheric icing conditions. These results showed that on superhydrophobic surfaces ice-adhesion strength was 3.5 times lower than on the polished aluminum substrate.

  18. Determination of Trace Anions in Concentrated Hydrogen Peroxide by Direct Injection Ion Chromatography with Conductivity Detection after Pt-Catalyzed On-Line Decomposition

    International Nuclear Information System (INIS)

    Kim, Do Hee; Lee, Bo Kyung; Lee, Dong Soo

    1999-01-01

    A method has been developed for the determination of trace anion impurities in concentrated hydrogen peroxide. The method involves on-line decomposition of hydrogen peroxide, ion chromatographic separation and subsequent suppressed-type conductivity detection. H 2 O 2 is decomposed in Pt-catalyst filled Gore-Tex membrane tubing and the resulting aqueous solution containing analytes is introduced to the injection valve of an ion chromatograph for periodic determinations. The oxygen gas evolving within the membrane tubing escapes freely through the membrane wall causing no problem in ion chromatographic analysis. Decomposition efficiency is above 99.99% at a flow rate of 0.4mL/min for a 30% hydrogen peroxide concentration. Analytes are quantitatively retained. The analysis results for several brands of commercial hydrogen peroxides are reported

  19. Caracterização da hipersensibilidade a luvas de látex em profissionais da odontologia - DOI: 10.4025/actascihealthsci.v29i1.103 Rubber latex gloves hypersensitivities in dental workers - DOI: 10.4025/actascihealthsci.v29i1.103

    Directory of Open Access Journals (Sweden)

    Ana Maria Sell

    2007-12-01

    Full Text Available As reações alérgicas ao látex vêm aumentando em profissionais da saúde e se manifestam como um incômodo local ou sintomatologia sistêmica. Para conhecer a freqüência das manifestações alérgicas nos usuários de luvas de látex foi realizada busca entre os profissionais da odontologia via aplicação de questionários. Foram aplicados 450 questionários e, dentre os respondedores (140, 19% relataram manifestar reações locais ao contato com as luvas de látex e 5% reações sistêmicas a outros produtos de látex. Cerca de 2,5% declararam dermatite de contato e reações sistêmicas (anafiláticas, 1,5% apenas dermatite de contato e 1% sintomas de anafilaxia ao uso das luvas. Vinte por cento dos profissionais atenderam pacientes com alergia ao látex e 29% declararam questionar, durante a anamnese, a respeito de alergia ao látex. As reações alérgicas a luvas de látex foram freqüentes e é objeto de preocupação entre os profissionais da odontologia.Allergic reactions to natural rubber latex have increased in dental practice affecting both the professional and the patients. Allergic reactions may range from skin disease to asthma and anaphylaxis. This study aimed at determining the incidence of latex gloves allergy among dental care workers. 450 allergy questionnaires were used to collect information on latex gloves reactions and 140 dental works answered them. Latex gloves reaction occurred in 19% of them and 5% reported allergic reactions to other latex products. 2.5% reported symptoms suggesting contact dermatitis and anaphylaxis hypersensitivities, 1.5% contact dermatitis, and 1% reported anaphylaxis symptoms when wearing them. 20% of them had patients who presented symptoms suggestive of anaphylaxis hypersensitivity to rubber gloves latex. Our study confirms that rubber latex gloves reactions are frequent among dental care workers, and dentists must be aware of the latex allergy in dental practice.

  20. Management of carotid Dacron patch infection: a case report using median sternotomy for proximal common carotid artery control and in situ polytetrafluoroethylene grafting.

    Science.gov (United States)

    Illuminati, Giulio; Calio', Francesco G; D'Urso, Antonio; Ceccanei, Gianluca; Pacilè, Maria Antonietta

    2009-01-01

    We report on a 58-year-old male who presented with an enlarging cervical hematoma 3 months following carotid endarterectomy with Dacron patch repair, due to septic disruption of the Dacron patch secondary to presumed infection. The essential features of this case are the control of the proximal common carotid artery gained through a median sternotomy, because the patient was markedly obese with minimal thyromental distance, and the treatment consisting of in situ polytetrafluoroethylene bypass grafting, due to the absence of a suitable autogenous saphenous vein. Median sternotomy is rarely required in case of reintervention for septic false aneurysms and hematomas following carotid endarterectomy but should be considered whenever difficult control of the common carotid artery, when entering the previous cervicotomy, is anticipated. In situ polytetrafluoroethylene grafting can be considered if autogenous vein material is lacking.

  1. Evaluación de la toxicidad hepática y renal aguda y subaguda del látex de Croton palanostigma (sangre de grado en animales de experimentación

    Directory of Open Access Journals (Sweden)

    Miguel Sandoval

    2005-06-01

    Full Text Available Objetivo: Determinar la toxicidad hepática y renal de la administración oral del látex de Croton palanostigma, en dosis terapéutica y de mayor concentración. Materiales y Métodos: Se evaluó 60 ratas albinas, machos, en dos grupos: con administración oral aguda por 7 dìas y otro con administración oral subaguda por 30 días ad libitum. En cada grupo se tuvo tres subgrupos: (A Látex diluido 1/1000 (dosis terapéutica, (B Látex diluido 1/100, (C Agua (grupo control. Medimos el peso del animal y consumo del bebedero. Después, bajo anestesia con éter, se obtuvo sangre por punción cardiaca y se centrifugó a 5000 rpm por 5 minutos para obtener plasma sanguíneo. Se determinó actividad de gamma glutamil transferasa y fosfatasa alcalina, se evaluó niveles de urea, creatinina, proteínas totales, albúmina y globulinas por espectrofotocolorimétría. Resultados: El consumo promedio del látex en el primer grupo fue: en A, 0,14 mL.kg-1/día-1/rata-1; en B, 1,34 mL/kg-1/día-1/rata-1; y, en C, agua. En el segundo grupo, fue: en A, 0,13 mL/kg-1/día-1/rata-1; en B, 1,21 mL/kg-1/día-1/rata-1; y, en C, agua. No hubo diferencia significativa en el consumo del látex diario entre los grupos tratados a 7 y 30 días. Las actividades de gamma glutamil transferasa y fosfatasa alcalina, así como los metabolitos sanguíneos y ratios hígado/peso animal y riñones/peso animal, de los grupos experimentales vs. grupo control, no presentaron diferencias significativas (p>0,05. Conclusiones: En condiciones experimentales, la administración oral de sangre de grado, aguda y subaguda, en dosis terapéuticas y de mayor concentración, no produce alteraciones bioquímicas hepáticas ni renales en animales de experimentación.

  2. Formation of SiO2/polytetrafluoroethylene hybrid superhydrophobic coating

    International Nuclear Information System (INIS)

    Zheng Yansheng; He Yi; Qing Yongquan; Zhuo Zhihao; Mo Qian

    2012-01-01

    Highlights: ► The coating showed the water contact angle of 165° and the water sliding angle of 6°. ► The hierarchical structure with the low surface energy leads to surface superhydrophobicity. ► We demonstrated a simple yet efficient approach to preparing superhydrophobic surface. - Abstract: Superhydrophobic coating has been fabricated on the glass substrates with modified SiO 2 sol and polytetrafluoroethylene emulsion through a sol–gel process. SiO 2 sol was modified with γ-glycidoxypropyl trimethoxysilane. The coatings were characterized by water contact angle measurement, Scanning electron microscope, Fourier transform infrared spectrometry, X-ray photoelectron spectroscopy and thermal synthetic analysis. The experimental results show that coatings exhibited superhydrophobic and heat-resistant property with a water average contact angle of 156° and sliding angle of 6°, coating has a rough surface with both micro- and nanoscale structures, γ-glycidoxypropyl trimethoxysilane enhanced the hydrophobicity of the coatings. Low surface energy of polymer and special structure of the coatings were responsible for the hydrophobic of the surfaces.

  3. Ablation of polytetrafluoroethylene using a continuous CO2 laser beam

    International Nuclear Information System (INIS)

    Tolstopyatov, E M

    2005-01-01

    The ablation of polytetrafluoroethylene (PTFE) is studied using a continuous CO 2 laser beam of 30-50 W at a mean intensity of 0.05-50 MW m -2 . The ablation products and changes in the target layer are examined using infrared spectroscopy, x-ray photoelectron spectroscopy, x-ray diffraction and electron microscopy. The main experiments were conducted with an unfocused beam of intensity 0.9-1.2 MW m -2 . The radiation-polymer interaction characteristics were found to change appreciably as the ablation conditions are approached. Within the polymer layer, light scattering diminishes and true resonant light absorption increases. Two distinct polymer components, which differ primarily in their resistance to CO 2 laser radiation, were found to exist under ablation conditions. The less stable component depolymerizes intensively, while the more resistant component is blown up into fibres by intense gas flow. The reasons behind this behaviour are discussed. Preliminary gamma irradiation of PTFE is found to have a significant influence on the laser ablation process

  4. Microstructure and tri biological properties of sputtered NbTex thin films

    International Nuclear Information System (INIS)

    Kassem, M.; Langlade, C.; Fayeulle, S.; Mathy, Y.; Pailharey, D.

    1997-01-01

    Thin NbTex films were deposited on steel by sputtering. Annealing was performed at several temperatures. Phase transition phenomena were analysed by X-ray diffraction (0-20 and grazing incidence). Depending on the conditions (Sputtering and annealing) the structure of the films changed from the NbTe2 (Two-dimensional) to the Nb3Te4 (Three-dimensional with linear channels) structural type and the intercalation of Te of Nb atoms within the parent structures was suggested. Films were evaluated under fretting conditions at 1 Hz in a dry environment. The displacement was ± 50 μ m and the contact pressure was 300 MPa. Friction coefficients were low, ranging from 0.08 to 0.18 depending on the film structure. The classical dependence of friction coefficient on pressure, well known for solid lubricants, was observed for NbTe2. Thickness and annealing temperature were shown to have a major effect of endurance. (author). 21 Refs., 7 Figs

  5. The potential of tumor-derived exosomes for noninvasive cancer monitoring.

    Science.gov (United States)

    Whiteside, Theresa L

    2015-01-01

    Tumor-derived exosomes (TEX) are emerging as a new type of cancer biomarker. TEX are membrane-bound, virus-size vesicles of endocytic origin present in all body fluids of cancer patients. Based on the expanding albeit incomplete knowledge of their biogenesis, secretion by tumor cells and cancer cell-specific molecular and genetic contents, TEX are viewed as promising, clinically-relevant surrogates of cancer progression and response to therapy. Preliminary proteomic, genetic and functional profiling of tumor cell-derived or cancer plasma-derived exosomes confirms their unique characteristics. Alterations in protein or nucleic acid profiles of exosomes in plasma of cancer patients responding to therapies appear to correlate with clinical endpoints. However, methods for TEX isolation and separation from the bulk of human plasma-derived exosomes are not yet established and their role as biomarkers remains to be confirmed. Further development and validation of TEX as noninvasive, liquid equivalents of tumor biopsies are necessary to move this effort forward.

  6. Superhydrophobic polytetrafluoroethylene thin films with hierarchical roughness deposited using a single step vapor phase technique

    International Nuclear Information System (INIS)

    Gupta, Sushant; Arjunan, Arul Chakkaravarthi; Deshpande, Sameer; Seal, Sudipta; Singh, Deepika; Singh, Rajiv K.

    2009-01-01

    Superhydrophobic polytetrafluoroethylene films with hierarchical surface roughness were deposited using pulse electron deposition technique. We were able to modulate roughness of the deposited films by controlling the beam energy and hence the electron penetration depth. The films deposited at higher beam energy showed contact angle as high as 166 o . The scanning electron and atomic force microscope studies revealed clustered growth and two level sub-micron asperities on films deposited at higher energies. Such dual-scale hierarchical roughness and heterogeneities at the water-surface interface was attributed to the observed contact angle and thus its superhydrophobic nature.

  7. Superhydrophobic polytetrafluoroethylene thin films with hierarchical roughness deposited using a single step vapor phase technique

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Sushant, E-mail: sushant3@ufl.ed [Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32611 (United States); Arjunan, Arul Chakkaravarthi [Sinmat Incorporated, 2153 SE Hawthorne Road, 129, Gainesville, Florida 32641 (United States); Deshpande, Sameer; Seal, Sudipta [Advanced Material Processing and Analysis Center, University of Central Florida, Orlando, Florida 32816 (United States); Singh, Deepika [Sinmat Incorporated, 2153 SE Hawthorne Road, 129, Gainesville, Florida 32641 (United States); Singh, Rajiv K. [Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32611 (United States)

    2009-06-30

    Superhydrophobic polytetrafluoroethylene films with hierarchical surface roughness were deposited using pulse electron deposition technique. We were able to modulate roughness of the deposited films by controlling the beam energy and hence the electron penetration depth. The films deposited at higher beam energy showed contact angle as high as 166{sup o}. The scanning electron and atomic force microscope studies revealed clustered growth and two level sub-micron asperities on films deposited at higher energies. Such dual-scale hierarchical roughness and heterogeneities at the water-surface interface was attributed to the observed contact angle and thus its superhydrophobic nature.

  8. Epoxidação "in situ" aplicada ao látex de borracha natural "In situ" epoxidation of natural rubber latex

    Directory of Open Access Journals (Sweden)

    Cristiane K. Santin

    2012-01-01

    Full Text Available O comportamento da borracha natural na forma látex frente à reação de epoxidação foi avaliado visando estabelecer as melhores condições reacionais sem a ocorrência de reações laterais, que promovem a coagulação do látex e o desenvolvimento de um aglomerado de borracha. Grupos epóxidos foram gerados através da reação de epoxidação a partir da formação in situ do ácido perfórmico. As amostras foram caracterizadas qualitativamente por espectroscopia de infravermelho (FTIR e o grau de modificação determinado por ressonância magnética nuclear de hidrogênio (1H-RMN. Análises de calorimetria exploratória diferencial (DSC demonstraram que a mobilidade da cadeia polimérica foi influenciada pela presença de grupos epóxidos, com aumento linear na temperatura de transição vítrea (Tg. Os resultados indicaram que a epoxidação do látex de borracha natural, sem a ocorrência de reações laterais, é possível e dependente das condições reacionais.Natural rubber latex was submitted to epoxidation reaction to establish the best reaction conditions without the occurrence of side reactions, which promote coagulation of the latex and development of an agglomerate of rubber. Epoxy groups were produced by in situ epoxidation with formic acid and hydrogen peroxide. The samples were characterized qualitatively by Fourier Transform Infrared (FTIR analysis and the degree of modification determined by Hydrogen Nuclear Magnetic Resonance Spectroscopy (1H-NMR analysis. A linear increase in the glass transition temperature (Tg was observed. The results show that the epoxidation of natural rubber latex is possible and depends on the reaction conditions.

  9. Mechanistic insights into the room temperature transitions of polytetrafluoroethylene during electron-beam irradiation

    Science.gov (United States)

    Fu, Congli; Yu, Xianwei; Zhao, Xiaofeng; Wang, Xiuli; Gu, Aiqun; Xie, Meiju; Chen, Chen; Yu, Zili

    2017-11-01

    In order to recognize the characteristic thermal transitions of polytetrafluoroethylene (PTFE) occurring at 19 °C and 30 °C, PTFE is irradiated on electron beam accelerator at room temperature and analyzed by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The results suggest that the two transition temperatures decrease considerably with increasing irradiation doses. Based on the results of structural analysis, the decrease of the two transition temperatures is supposed to be highly relevant to the structural changes. In particular, the content and structure of the side groups generated in PTFE are responsible for the variations of the two thermal transitions after irradiation, offering fundamental insights into the reaction mechanisms of PTFE during irradiation.

  10. Desarrollo de nuevas formulaciones de látex de caucho natural libres de n-nitrosaminas, hipoalergénicas y ecológicas, y su caracterización por RMN de campo bajo

    OpenAIRE

    Brasero Espada, Justo

    2016-01-01

    Los artículos de látex de caucho natural están extensamente presentes en nuestra sociedad, ya que se cifran en más de 40,000 los artículos que contienen látex, incluyendo más de 400 dispositivos bio‐médicos. Este éxito se debe a que es un material idóneo para fabricar artículos de paredes muy delgadas con excelentes propiedades barrera y elásticas. Estas propiedades barrera proporcionan una protección muy eficaz contra virus y bacterias que, unidas a la durabilidad, costo y confort, han hecho...

  11. How to design the optimal self-expandable oesophageal metallic stents: 22 years of experience in 645 patients with malignant strictures.

    Science.gov (United States)

    Na, Han Kyu; Song, Ho-Young; Kim, Jin Hyoung; Park, Jung-Hoon; Kang, Min Kyoung; Lee, Jongjin; Oh, Se Jin

    2013-03-01

    To evaluate the clinical efficacy and safety of self-expandable metallic stent (SEMS) placement for malignant oesophageal strictures and their relationship with stent designs. Seven generations of SEMS were used to treat 645 consecutive patients with oesophageal strictures. Logistic regression models were constructed to identify predictive factors associated with complications. Stent placement was technically successful in 641 of 645 patients (99.4%). The clinical success rate was 95.5%. There were 260 (40.3%) complications after stent placement. Due to complications, 68 stents were removed; 66 of 68 stents (97.1%) were removed successfully. Stainless steel (SS) stents (odds ratio [OR] 4.18; 95% confidence interval [CI] 2.10, 8.32) and radiation therapy (RT) before stent placement (OR 4.23; CI 2.02, 8.83) were significantly associated with severe pain. Flared ends (OR 9.63; CI 3.38, 27.43), stricture length stent diameter stent migration. Polyurethane membranes were associated with more frequent tumour ingrowth than polytetrafluoroethylene (PTFE) membranes (P = 0.002). Despite the relatively high complication rate, retrievable self-expandable PTFE-covered nitinol stents equipped with a head and a tail appeared to be an effective treatment for malignant oesophageal strictures.

  12. Thermal comfort of dual-chamber ski gloves

    Science.gov (United States)

    Dotti, F.; Colonna, M.; Ferri, A.

    2017-10-01

    In this work, the special design of a pair of ski gloves has been assessed in terms of thermal comfort. The glove 2in1 Gore-Tex has a dual-chamber construction, with two possible wearing configurations: one called “grip” to maximize finger flexibility and one called “warm” to maximize thermal insulation in extremely cold conditions. The dual-chamber gloves has been compared with two regular ski gloves produced by the same company. An intermittent test on a treadmill was carried out in a climatic chamber: it was made of four intense activity phases, during which the volunteer ran at 9 km/h on a 5% slope for 4 minutes, spaced out by 5-min resting phases. Finger temperature measurements were compared with the thermal sensations expressed by two volunteers during the test.

  13. Evaluación de agentes de coagulación para la producción de láminas de caucho seco a partir de Látex multiclonal de “Hevea Brasiliensis”

    OpenAIRE

    Giraldo Díaz, Alejandra María; López Aristizábal, Paulina

    2016-01-01

    El presente trabajo consiste en la evaluación de tres agentes de coagulación, uno convencional (ácido acético) y dos alternativos (ácido cítrico y limoneno) para la producción de láminas de caucho seco a partir del látex de Hevea brasiliensis, extraído del Nordeste Antioqueño en el corregimiento San José del Nus -- Se realizó una caracterización del látex, en la que se obtuvo una densidad de 0,97 gr/ml, un porcentaje de solidos de 31,14%, un porcentaje de caucho seco de 29,4%, un TGA con la p...

  14. Corrigendum.

    Science.gov (United States)

    2017-04-01

    Holden A, Merrilees S, Buckley B, et al. First-in-human experience with the Gore balloon-expandable covered endoprosthesis in iliac artery occlusive disease. J Endovasc Ther. 2017;24:11-18. doi: 10.1177/1526602816680570 .

  15. Multi-layer composite structure covered polytetrafluoroethylene for visible-infrared-radar spectral Compatibility

    Science.gov (United States)

    Qi, Dong; Cheng, Yongzhi; Wang, Xian; Wang, Fang; Li, Bowen; Gong, Rongzhou

    2017-12-01

    In this paper, a polytetrafluoroethylene (PTFE) top-covered multi-layer composite structure PTFE/H s/(Ge/ZnS)3 (H s represents the surface layer ZnS with various thicknesses) for spectral compatibility is proposed and investigated theoretically and experimentally. A substantial decline of glossiness from over 200 Gs to 74.2 Gs could be realized, due to high roughness and interface reflection of the 800 nm PTFE protection layer. In addition, similar to the structure of H s/(Ge/ZnS)3, the designed structure with a certain color exhibits ultra-low emissivity of average 0.196 at 8-14 µm and highly transparent performance of 96.45% in the radar frequency range of 2-18 GHz. Our design will provide an important reference for the practical applications of the spectral compatible multilayer films.

  16. Removable polytetrafluoroethylene template based epitaxy of ferroelectric copolymer thin films

    Science.gov (United States)

    Xia, Wei; Chen, Qiusong; Zhang, Jian; Wang, Hui; Cheng, Qian; Jiang, Yulong; Zhu, Guodong

    2018-04-01

    In recent years ferroelectric polymers have shown their great potentials in organic and flexible electronics. To meet the requirements of high-performance and low energy consumption of novel electronic devices and systems, structural and electrical properties of ferroelectric polymer thin films are expected to be further optimized. One possible way is to realize epitaxial growth of ferroelectric thin films via removable high-ordered polytetrafluoroethylene (PTFE) templates. Here two key parameters in epitaxy process, annealing temperature and applied pressure, are systematically studied and thus optimized through structural and electrical measurements of ferroelectric copolymer thin films. Experimental results indicate that controlled epitaxial growth is realized via suitable combination of both parameters. Annealing temperature above the melting point of ferroelectric copolymer films is required, and simultaneously moderate pressure (around 2.0 MPa here) should be applied. Over-low pressure (around 1.0 MPa here) usually results in the failure of epitaxy process, while over-high pressure (around 3.0 MPa here) often results in residual of PTFE templates on ferroelectric thin films.

  17. Decomposition pathways of polytetrafluoroethylene by co-grinding with strontium/calcium oxides.

    Science.gov (United States)

    Qu, Jun; He, Xiaoman; Zhang, Qiwu; Liu, Xinzhong; Saito, Fumio

    2017-06-01

    Waste polytetrafluoroethylene (PTFE) could be easily decomposed by co-grinding with inorganic additive such as strontium oxide (SrO), strontium peroxide (SrO 2 ) and calcium oxide (CaO) by using a planetary ball mill, in which the fluorine was transformed into nontoxic inorganic fluoride salts such as strontium fluoride (SrF 2 ) or calcium fluoride (CaF 2 ). Depending on the kind of additive as well as the added molar ratio, however, the reaction mechanism of the decomposition was found to change, with different compositions of carbon compounds formed. CO gas, the mixture of strontium carbonate (SrCO 3 ) and carbon, only SrCO 3 were obtained as reaction products respectively with equimolar SrO, excess SrO and excess SrO 2 to the monomer unit CF 2 of PTFE were used. Excess amount of CaO was needed to effectively decompose PTFE because of its lower reactivity compared with strontium oxide, but it promised practical applications due to its low cost.

  18. Novel Ultrafine Fibrous Poly(tetrafluoroethylene Hollow Fiber Membrane Fabricated by Electrospinning

    Directory of Open Access Journals (Sweden)

    Qinglin Huang

    2018-04-01

    Full Text Available Novel poly(tetrafluoroethylene (PTFE hollow fiber membranes were successfully fabricated by electrospinning, with ultrafine fibrous PTFE membranes as separation layers, while a porous glassfiber braided tube served as the supporting matrix. During this process, PTFE/poly(vinylalcohol (PVA ultrafine fibrous membranes were electrospun while covering the porous glassfiber braided tube; then, the nascent PTFE/PVA hollow fiber membrane was obtained. In the following sintering process, the spinning carrier PVA decomposed; meanwhile, the ultrafine fibrous PTFE membrane shrank inward so as to further integrate with the supporting matrix. Therefore, the ultrafine fibrous PTFE membranes had excellent interface bonding strength with the supporting matrix. Moreover, the obtained ultrafine fibrous PTFE hollow fiber membrane exhibited superior performances in terms of strong hydrophobicity (CA > 140°, high porosity (>70%, and sharp pore size distribution. The comprehensive properties indicated that the ultrafine fibrous PTFE hollow fiber membranes could have potentially useful applications in membrane contactors (MC, especially membrane distillation (MD in harsh water environments.

  19. Friction transfer of polytetrafluoroethylene (PTFE) to produce nanoscale features and influence cellular response in vitro.

    Science.gov (United States)

    Kearns, V R; Doherty, P J; Beamson, G; Martin, N; Williams, R L

    2010-07-01

    A large number of cell types are known to respond to chemical and topographical patterning of substrates. Friction transfer of polytetrafluoroethylene (PTFE) onto substrates has been shown to produce continuous, straight, parallel nanofibres. Ammonia plasma treatment can be used to defluorinate the PTFE, decreasing the dynamic contact angle. Fibroblast and epithelial cells were elongated and oriented with their long axis parallel to the fibres, both individually and in clusters. The fibres restricted cell migration. Cell alignment was slightly reduced on the plasma-treated fibres. These results indicated that although surface topography can affect cellular response, surface chemistry also mediates the extent of this response.

  20. High-performance membrane-electrode assembly with an optimal polytetrafluoroethylene content for high-temperature polymer electrolyte membrane fuel cells

    DEFF Research Database (Denmark)

    Jeong, Gisu; Kim, MinJoong; Han, Junyoung

    2016-01-01

    Although high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) have a high carbon monoxide tolerance and allow for efficient water management, their practical applications are limited due to their lower performance than conventional low-temperature PEMFCs. Herein, we present a high......-performance membrane-electrode assembly (MEA) with an optimal polytetrafluoroethylene (PTFE) content for HT-PEMFCs. Low or excess PTFE content in the electrode leads to an inefficient electrolyte distribution or severe catalyst agglomeration, respectively, which hinder the formation of triple phase boundaries...

  1. 28 October 2013- Former US Vice President A. Gore signing the guest book with Technology Department Head F. Bordry, Head of International Relations R. Voss, Director for Research and Scientific Computing S. Bertolucci and CMS Collaboration Spokesperson J. Incandela.

    CERN Multimedia

    Maximilien Brice

    2013-01-01

    28 October 2013- Former US Vice President A. Gore signing the guest book with Technology Department Head F. Bordry, Head of International Relations R. Voss, Director for Research and Scientific Computing S. Bertolucci and CMS Collaboration Spokesperson J. Incandela.

  2. Characteristics improvement of hydrophobic polytetrafluoroethylene-platinum catalysts for tritium separation

    International Nuclear Information System (INIS)

    Popescu, I.; Ionita, Gh.; Dobrinescu, D.; Varlam, C.; Stefanescu, I.

    2006-01-01

    Full text: Based on the long experience of the authors in the preparation, testing and evaluation of the performances of hydrophobic catalysts and based on the reviewed references, this paper presents up-to-date R and D activities on the preparation methods and applications of the hydrophobic catalysts in tritium separation. The objectives of the paper are: how to improve the characteristics and performance of platinum hydrophobic catalysts; to assess and find a new procedure for the preparation of a new improved hydrophobic catalyst. From reviewed references one can conclude that platinum is the most active and efficient catalytic metal while the polytetrafluoroethylene is the best wet-proofing agent. A new improved hydrophobic Pt-catalyst has been proposed and its testing is now underway. The main steps and experimental conditions of preparation are thoroughly discussed. A new wet-proofing agent and new binders (titanium dioxide, cerium dioxide, zirconium dioxide) with a catalytic role are proposed and tested. The physico-structural parameters of the improved catalyst have been determined and are discussed in detail. The new proposal is a promising idea to improve the performance of conventional hydrophobic Pt-catalysts. (authors)

  3. Functional properties of poly(tetrafluoroethylene) (PTFE) gasket working in nuclear reactor conditions

    Science.gov (United States)

    Wyszkowska, Edyta; Leśniak, Magdalena; Kurpaska, Lukasz; Prokopowicz, Rafal; Jozwik, Iwona; Sitarz, Maciej; Jagielski, Jacek

    2018-04-01

    In this study structural and nanomechanical properties of polytetrafluoroethylene (PTFE) used as a gasket in the nuclear reactor have been deeply investigated. In order to reveal structural changes caused by long-term pressure, temperature and irradiation (possibly neutron and gamma), methods such as SEM, X-ray diffraction and Raman Spectroscopy have been used. Nanomechanical properties such as Young Modulus and hardness were investigated by means of the nanoindentation technique. Presented study confirmed the influence of working (radiative) environment on the functional properties of PTFE. The results of Raman spectroscopy and X-ray diffraction techniques revealed shift of the major band positions and band intensities increase. Moreover, changes of hardness and Young Modulus values of the irradiated material with respect to the virgin specimen have been recorded. This phenomenon can be attributed to the modifications in crystallinity of the material. Presented work suggest that morphology of the irradiated material altered from well-ordered parallel fibers to more dense and thicker ones.

  4. Unruptured Aneurysm of Sinus of Valsalva Coexisting with the Large Ventricular Septal Defect and Severe Aortic Regurgitation in a Young Man

    Directory of Open Access Journals (Sweden)

    Pouya Nezafati

    2015-01-01

    Full Text Available Introduction. Unruptured sinus of valsalva aneurysm (SVA is a rare congenital anomaly, particularly, when it coexists with a ventricular septal defect (VSD and aortic regurgitation due to the prolapse of the elongated aortic cusp into the VSD. In this report, we present the case of a 19-year-old young man with VSD challenging in spite of dyspnea and lower limb edema. Presentation of Case. Its diagnosis was made on the basis of transthoracic echocardiography results. Surgical management consisted of replacing the SVA with mechanical valve prosthesis. A Gore-Tex patch repaired the VSD. Discussion. In the follow-up periods, clinical and echocardiographic tests showed that the patient was in excellent status. Conclusion. SVA requires a surgical procedure due to its high risk of mortality in unoperated patients and a good safety of surgery.

  5. Uso da biomembrana de látex em cavidade exenterada: relato de caso The use of latex biomembrane in exenteration: case report

    Directory of Open Access Journals (Sweden)

    Fernando Fugimoto

    2007-10-01

    Full Text Available A membrana de látex é um material extraído da Hevea brasiliensis, e devido às suas propriedades neoangiogênicas, de adesão celular e formação de matriz extracelular, é utilizada em recobrimentos de úlceras, meringoplastias e outras feridas, com sucesso. Neste caso descrevemos seu uso, inédito, na ferida pós-exenteração orbitária por carcinoma basocelular em paciente do sexo masculino, 72 anos, procedente da Bahia com lesão na pálpebra do olho esquerdo há dois anos com prurido, sangramento, lacrimejamento, e dor. Ao exame oftalmológico do olho esquerdo evidenciou-se lesão ulcerada de pálpebra superior e canto medial, hiperemia conjuntival, afilamento corneano, catarata, perfuração ocular. Sem alterações significativas à direita. A tomografia de órbitas revelou lesão expansiva palpebral com invasão pré-septal, osso frontal e lâmina papirácea à esquerda. Realizada exenteração total com curativo de biomembrana de látex; troca a cada 24 horas nos primeiros sete dias e a cada 48 horas nos outros sete dias. Retirou-se a biomembrana de látex por não ter sido evidenciada granulação, o que só ocorreu após um mês e quinze dias. A exenteração orbitária consiste na retirada de todo o conteúdo da órbita, incluindo olho e partes moles. É considerada total quando as pálpebras são incluídas, e subtotal quando as mesmas são preservadas. Existem várias técnicas de reconstrução da cavidade exenterada: como granulação espontânea, enxerto de pele, retalho frontal, retalho miocutâneo, entre outros. Neste caso utilizamos curativo com biomembrana de látex, material que se mostrou eficaz no recobrimento de outros tecidos cruentos como úlceras, mas sem o mesmo sucesso em nossa experiência. Mais estudos são necessários para que possamos concluir as vantagens e desvantagens do uso da biomembrana de látex na área da oftalmologia.The latex biomembrane is a material from Hevea brasiliensis and has angiogenic

  6. Use of X-ray photoelectron spectroscopy to study radiation and thermal effects in polytetrafluoroethylene

    International Nuclear Information System (INIS)

    Wheeler, D.R.; Pepper, S.V.

    1990-01-01

    X-ray photoelectron spectroscopy of the surface and mass spectroscopy of the gas evolved during irradiation and subsequent heating of irradiated polytetrafluoroethylene (PTFE) indicated that the effect of electron irradiation was the same as that of x-irradiation. Saturated fluorocarbon gas was evolved during irradiation and a cross-linked or branched network formed in the surface region. Heating irradiated PTFE to temperatures below 200C resulted in the evolution of additional saturated fluorocarbon gas but no change in the surface. From 200C to 300C, lightly damaged PTFE did not change further, but severely damaged PTFE emitted unsaturated fluorocarbons while the surface underwent apparent partial recovery. These observations demonstrate the thermal instability of the irradiated PTFE surface and allow elaboration of the existing model of radiation damage in PTFE

  7. The biomechanical effects of polytetrafluoroethylene suture augmentations in lateral-row rotator cuff repairs in an ovine model.

    Science.gov (United States)

    Beimers, Lijkele; Lam, Patrick H; Murrell, George A C

    2014-10-01

    This study investigated the biomechanical effects of expanded polytetrafluoroethylene (ePTFE) suture augmentation patches in rotator cuff repair constructs. The infraspinatus tendon in 24 cadaveric ovine shoulders was repaired using an inverted horizontal mattress suture with 2 knotless bone anchors (ArthroCare, Austin, TX, USA) in a lateral-row configuration. Four different repair groups (6 per group) were created: (1) standard repair using inverted horizontal mattress sutures, (2) repair with ePTFE suture augmentations on the bursal side of the tendon, (3) repair with ePTFE suture augmentations on the articular side, and, (4) repair with ePTFE suture augmentations on both sides of the tendon. Footprint contact pressure, stiffness, and the load to failure of the repair constructs were measured. Repairs with ePTFE suture augmentations on the bursal side exerted significantly more footprint contact pressure (0.40 ± 0.01 MPa) than those on the articular side (0.34 ± 0.02 MPa, P = .04) and those on both sides (0.33 ± 0.02 MPa, P = .01). At 15 degrees of abduction, ePTFE-augmented repairs on the bursal side had higher footprint contact pressure (0.26 ± 0.03 MPa) compared with standard repairs (0.15 ± 0.02 MPa, P = .01) and with ePTFE-augmented repairs on the articular side (0.18 ± 0.02 MPa, P = .03). The ePTFE-augmented repairs on the bursal side demonstrated significantly higher failure loads (178 ± 18 N) than standard repairs (120 ± 17 N, P = .04). Inverted horizontal mattress sutures augmented with ePTFE patches on the bursal side of the tendon enhanced footprint contact pressures and the ultimate load to failure of lateral-row rotator cuff repairs in an ovine model. Copyright © 2014 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  8. Multiple Scattering Approach to Polarization Dependence of F K-Edge XANES Spectra for Highly Oriented Polytetrafluoroethylene (PTFE) Thin Film

    International Nuclear Information System (INIS)

    Nagamatsu, S.; Ono, M.; Kera, S.; Okudaira, K. K.; Fujikawa, T.; Ueno, N.

    2007-01-01

    The polarization dependence of F K-edge X-ray absorption near edge structure (XANES) spectra of highly-oriented thin-film of polytetrafluoroethylene (PTFE) has been analyzed by using multiple scattering theory. The spectra show clear polarization dependence due to the highly-oriented structure. The multiple scattering calculations reflects a local structure around an absorbing atom. The calculated results obtained by considering intermolecular-interactions are in good agreement with the observed polarization-dependence. We have also analyzed structural models of the radiation damaged PTFE films

  9. Bioactive surface modifications on inner walls of poly-tetra-fluoro-ethylene tubes using dielectric barrier discharge

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Yong Ki [Department of Physics, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Heat Treatment and Surface Engineering R and D Group, Korea Institute of Industrial Technology, Incheon 406-840 (Korea, Republic of); Park, Daewon; Kim, Hoonbae [Department of Physics, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Lee, Hyerim; Park, Heonyong [Department of Molecular Biology, Dankook University, Yongin 448-701 (Korea, Republic of); Kim, Hong Ja [Department of Internal Medicine, Dankook University, Cheonan 330-714 (Korea, Republic of); Jung, Donggeun, E-mail: djung@skku.ac.kr [Department of Physics, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2014-03-01

    Graphical abstract: - Highlights: • The surface modification of the inner walls of poly-tetra-fluoro-ethylene (PTFE) tubing was carried out to improve vascular grafts. • Focus was centered on the cell attachment of the inner wall of the PTFE by sequential processes of hydrogen plasma treatment, hydrocarbon deposition, and reactive plasma treatment using micro plasma discharge. - Abstract: Bioactive surface modification can be used in a variety of medical polymeric materials in the fields of biochips and biosensors, artificial membranes, and vascular grafts. In this study, the surface modification of the inner walls of poly-tetra-fluoro-ethylene (PTFE) tubing was carried out to improve vascular grafts, which are made of biocompatible material for the human body in the medical field. Focus was centered on the cell attachment of the inner wall of the PTFE by sequential processes of hydrogen plasma treatment, hydrocarbon deposition, and reactive plasma treatment on the PFTE surface using micro plasma discharge. Micro plasma was generated by a medium-frequency alternating current high-voltage generator. The preliminary modification of PTFE was conducted by a plasma of hydrogen and argon gases. The hydrocarbon thin film was deposited on modified PTFE with a mixture of acetylene and argon gases. The reactive plasma treatment using oxygen plasma was done to give biocompatible functionality to the inner wall surface. The hydrophobic surface of bare PTFE is made hydrophilic by the reactive plasma treatment due to the formation of carbonyl groups on the surface. The reactive treatment could lead to improved attachment of smooth muscle cells (SMCs) on the modified PTFE tubing. Fourier transform infrared absorption spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and water contact angle measurement were used for the analysis of the surface modification. The SMC-attached PTFE tube developed will be applicable to in vitro human vasculature

  10. Bioactive surface modifications on inner walls of poly-tetra-fluoro-ethylene tubes using dielectric barrier discharge

    International Nuclear Information System (INIS)

    Cho, Yong Ki; Park, Daewon; Kim, Hoonbae; Lee, Hyerim; Park, Heonyong; Kim, Hong Ja; Jung, Donggeun

    2014-01-01

    Graphical abstract: - Highlights: • The surface modification of the inner walls of poly-tetra-fluoro-ethylene (PTFE) tubing was carried out to improve vascular grafts. • Focus was centered on the cell attachment of the inner wall of the PTFE by sequential processes of hydrogen plasma treatment, hydrocarbon deposition, and reactive plasma treatment using micro plasma discharge. - Abstract: Bioactive surface modification can be used in a variety of medical polymeric materials in the fields of biochips and biosensors, artificial membranes, and vascular grafts. In this study, the surface modification of the inner walls of poly-tetra-fluoro-ethylene (PTFE) tubing was carried out to improve vascular grafts, which are made of biocompatible material for the human body in the medical field. Focus was centered on the cell attachment of the inner wall of the PTFE by sequential processes of hydrogen plasma treatment, hydrocarbon deposition, and reactive plasma treatment on the PFTE surface using micro plasma discharge. Micro plasma was generated by a medium-frequency alternating current high-voltage generator. The preliminary modification of PTFE was conducted by a plasma of hydrogen and argon gases. The hydrocarbon thin film was deposited on modified PTFE with a mixture of acetylene and argon gases. The reactive plasma treatment using oxygen plasma was done to give biocompatible functionality to the inner wall surface. The hydrophobic surface of bare PTFE is made hydrophilic by the reactive plasma treatment due to the formation of carbonyl groups on the surface. The reactive treatment could lead to improved attachment of smooth muscle cells (SMCs) on the modified PTFE tubing. Fourier transform infrared absorption spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and water contact angle measurement were used for the analysis of the surface modification. The SMC-attached PTFE tube developed will be applicable to in vitro human vasculature

  11. Vascular Biocompatibility of a Triple Layered Self Expanding Stent-Graft in a Dog Mode

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Jae Ik; Won, Je Hwan; Jang, Eun Ho; Lee, Sung Yeong; Ko, Kwang Tae [Dept. of Radiology, Ajou University School of Medicine, Suwon (Korea, Republic of); Jin, Bo Hwan [Medical Science Research Center, Ajou University School of Medicine, Suwon (Korea, Republic of); Lee, June Woo [Dept. of Radiology, Busan National University College of Medicine, Busan (Korea, Republic of)

    2012-02-15

    To evaluate performance and biocompatibility of a newly designed self-expanding stent graft, which consisted of two nitinol stents and an intervening expanded polytetrafluoroethylene membrane in a dog artery model. Twelve stent grafts were placed in the aorta of 6 dogs (beagle, mean body weight 11 kg) for 4 weeks (n = 4) and 12 weeks (n = 8). Luminal diameters were measured for each segment (the proximal bare, the middle graft, the distal bare) by angiographies after implantation and follow up periods. Percent luminal stenosis based on angiographies, histomorphometric, histologic, and scanning electron microscopic analyses of each segments were performed. Blood flow through the stent grafts was good after implantation and during the follow up period, without thrombotic occlusion or stent graft migration. The mean percent luminal stenosis of the proximal bare, the middle grafted and the distal bare segments after 12 weeks were 13.5%, 3.9%, 9.6% retrospectively. The mean neointimal areas of the middle grafted segment were 4.39 mm{sup 2} (4 week) and 4.92 mm{sup 2} (12 week). Mature endothelialization was evident in over 70% of the area of the stented artery after 4 weeks and in over 90% after 12 weeks. The stent graft was well placed in the attempted area without migration. During the 12-week-follow up period, it showed a good patency without thrombotic occlusion or significant in-stent luminal stenosis. Endothelialization was rapid and nearly complete. Neointima was thin and smooth on the middle graft segment and thicker and irregular on the bare segments.

  12. Vascular Biocompatibility of a Triple Layered Self Expanding Stent-Graft in a Dog Mode

    International Nuclear Information System (INIS)

    Bae, Jae Ik; Won, Je Hwan; Jang, Eun Ho; Lee, Sung Yeong; Ko, Kwang Tae; Jin, Bo Hwan; Lee, June Woo

    2012-01-01

    To evaluate performance and biocompatibility of a newly designed self-expanding stent graft, which consisted of two nitinol stents and an intervening expanded polytetrafluoroethylene membrane in a dog artery model. Twelve stent grafts were placed in the aorta of 6 dogs (beagle, mean body weight 11 kg) for 4 weeks (n = 4) and 12 weeks (n = 8). Luminal diameters were measured for each segment (the proximal bare, the middle graft, the distal bare) by angiographies after implantation and follow up periods. Percent luminal stenosis based on angiographies, histomorphometric, histologic, and scanning electron microscopic analyses of each segments were performed. Blood flow through the stent grafts was good after implantation and during the follow up period, without thrombotic occlusion or stent graft migration. The mean percent luminal stenosis of the proximal bare, the middle grafted and the distal bare segments after 12 weeks were 13.5%, 3.9%, 9.6% retrospectively. The mean neointimal areas of the middle grafted segment were 4.39 mm 2 (4 week) and 4.92 mm 2 (12 week). Mature endothelialization was evident in over 70% of the area of the stented artery after 4 weeks and in over 90% after 12 weeks. The stent graft was well placed in the attempted area without migration. During the 12-week-follow up period, it showed a good patency without thrombotic occlusion or significant in-stent luminal stenosis. Endothelialization was rapid and nearly complete. Neointima was thin and smooth on the middle graft segment and thicker and irregular on the bare segments.

  13. Self-Expandable Metal Stents and Trans-stent Light Delivery: Are Metal Stents and Photodynamic Therapy Compatible?

    Science.gov (United States)

    Wang, Luo-Wei; Li, Li-Bo; Li, Zhao-Shen; Chen, Yang K; Hetzel, Fred W.; Huang, Zheng

    2008-01-01

    Background and Objectives: Obstructive non-small cell lung cancer and obstructive esophageal cancer are US FDA approved indications of photodynamic therapy (PDT). The usefulness of PDT for the treatment of cholangiocarcinoma is currently under clinical investigation. Endoscopic stenting for lumen restoration is a common palliative intervention for those indications. It is important to assess whether self-expandable metal stents are compatible with trans-stent PDT light delivery. Study Design/Materials and Methods: Direct effects of various components of metal biliary (n = 2), esophageal (n = 2), and bronchial (n = 1) stents on PDT light transmittance and distribution were examined using a point or linear light source (630 or 652 nm diode laser). Resected pig biliary duct and esophageal wall tissues were used to examine the feasibility of PDT light delivery through the fully expanded metal stents. Results: While using a point light source, the metal components (thread and joint) of the stent could cause a significant shadow effect. The liner material (polytetrafluoroethylene or polyurethane) could cause various degrees of light absorption. When the stent was covered with a thin layer of biliary duct and esophageal tissues containing all wall layers, the shadow effect could be mitigated due to tissue scattering. Conclusions: This study clearly demonstrates that it is feasible to combine stenting and PDT for the treatment of luminal lesions. PDT light dose should be adjusted to counteract the reduction of light transmittance caused by the metal and liner materials of stent. PMID:18951422

  14. Changes in the chemical structure of polytetrafluoroethylene induced by electron beam irradiation in the molten state

    CERN Document Server

    Lappan, U; Lunkwitz, K

    2000-01-01

    Polytetrafluoroethylene (PTFE) was exposed to electron beam radiation at elevated temperature above the melting point under nitrogen atmosphere and in vacuum for comparison. Fourier-transform infrared (FTIR) spectroscopy was used to study the changes in the chemical structure. The irradiation under nitrogen atmosphere leads to the same structures as described recently for PTFE irradiated in vacuum. Trifluoromethyl branches and double bond structures were detected. The concentrations of terminal and internal double bonds are higher after irradiation under nitrogen than in vacuum. Annealing experiments have shown that the thermal oxidative stability of the radiation-modified PTFE is reduced compared to unirradiated PTFE. The reason are the formation of unstable structures such as double bonds.

  15. Impact of Emissions from Commercial Shipping During TexAQS 2006

    Science.gov (United States)

    Williams, E.; Lerner, B.; Murphy, P.

    2007-12-01

    Commercial marine vessels range in size from small fishing boats (20-30 meters in length) to extremely large container ships (over 300 meters in length). These ships almost without exception use diesel engines for propulsion and auxiliary power generation. The larger ships, comprising bulk carriers, tankers and container carriers, utilize diesel engines that produce power in the 10 MW to 100 MW range. These engines typically consume heavy fuel oils which are high in sulfur content (1%-4.5% by weight). These engines are also extremely efficient, converting essentially all of the carbon in the fuel to CO2, but also emitting NOx, CO, SO2, VOCs, and PM. During TexAQS 2006 our measurements on board the NOAA research ship Ronald H. Brown allowed us to characterize the emissions from a large number of commercial marine vessels. The measurements provided the means to calculate mass-based emission factors for many of the compounds noted above. With the information broadcast by these vessels over the Automated Information System, we have unequivocally determined the emission factors for over 200 vessels both at dock and underway. Our data largely confirm published average emission factors, but also show significant variability especially with NOx. This talk will present those results and then use the data to show that emissions of NOx and SO2 from these vessels are not negligible in the Houston-Galveston region.

  16. Adhesion, friction and wear between polytetrafluoroethylene and nitrogen-implanted stainless steel

    International Nuclear Information System (INIS)

    Yang, E.; Hirvonen, J.P.; Raesaenen, M.; Toivanen, R.O.

    1992-01-01

    Adhesion, friction and wear of polytetrafluoroethylene (PTFE), carbon-reinforced PTFE, and glass-reinforced PTFE in sliding contact with nitrogen-implanted and unimplanted AISI 316 stainless steel were determined. The transfer of PTFE within the first 10 unidirectional traverses was investigated using the 19 F(p,αγ) 16 O nuclear reaction. External proton beam induced X-ray emission (PIXE) was used to determine the metal transfer from AISI 316 to pin heads. Nitrogen implantation considerably reduced the transfer of PTFE to the steel surface, and the transfer of the metallic elements from stainless steel to the PTFE-based composites. Furthermore, a lower friction coefficient was observed for nitrogen-implanted samples within the first 400 revolutions. The wear of PTFE, glass-reinforced and carbon-reinforced PTFE pins was only slightly reduced on the nitrogen-implanted surface, although a significant improvement in the wear of the steel was observed. Transmission electron microscopy (TEM) examination of wear debris revealed that PTFE was amorphized during the transfer process. However, no change in the structure of the pin head prior to the transfer was detected with an IR spectrophotometer. (orig.)

  17. Study on surface adhesion of Plasma modified Polytetrafluoroethylene hollow fiber membrane

    Science.gov (United States)

    Chen, Jiangrong; Zhang, Huifeng; Liu, Guochang; Guo, Chungang; Lv, Jinglie; Zhangb, Yushan

    2018-01-01

    Polytetrafluoroethylene (PTFE) is popular membrane material because of its excellent thermal stability, chemical stability and mechanical stability. However, the low surface energy and non-sticky property of PTFE present challenges for modification. In the present study, plasma treatment was performed to improve the surface adhesion of PTFE hollow fiber membrane. The effect of discharge voltage, treatment time on the adhesion of PTFE hollow fiber membrane was symmetrically evaluated. Results showed that the plasma treatment method contributed to improve the surface activity and roughness of PTFE hollow fiber membrane, and the adhesion strength depend significantly on discharge voltage, which was beneficial to seepage pressure of PTFE hollow fiber membrane module. The adhesion strength of PTFE membrane by plasma treated at 220V for 3min reached as high as 86.2 N, far surpassing the adhesion strength 12.7 N of pristine membrane. Furthermore, improvement of content of free radical and composition analysis changes of the plasma modified PTFE membrane were investigated. The seepage pressure of PTFE membrane by plasma treated at 220V for 3min was 0.375 MPa, which means that the plasma treatment is an effective technique to improve the adhesion strength of membrane.

  18. The clinical effects of Kinesio® Tex taping: A systematic review.

    Science.gov (United States)

    Morris, D; Jones, D; Ryan, H; Ryan, C G

    2013-05-01

    Kinesio(®) Tex tape (KTT) is used in a variety of clinical settings. The purpose of this study was to investigate the effect of KTT from randomized controlled trials (RCTs) in the management of clinical conditions. A systematic literature search of CINAHL; MEDLINE; OVID; AMED; SCIENCE DIRECT; PEDRO; www.internurse.com; SPORT DISCUS; BRITISH NURSING INDEX; www.kinesiotaping.co.uk; www.kinesiotaping.com; COCHRANE CENTRAL REGISTER OF CLINICAL TRIALS; and PROQUEST was performed up to April 2012. The risk of bias and quality of evidence grading was performed using the Cochrane collaboration methodology. Eight RCTs met the full inclusion/exclusion criteria. Six of these included patients with musculoskeletal conditions; one included patients with breast-cancer-related lymphedema; and one included stroke patients with muscle spasticity. Six studies included a sham or usual care tape/bandage group. There was limited to moderate evidence that KTT is no more clinically effective than sham or usual care tape/bandage. There was limited evidence from one moderate quality RCT that KTT in conjunction with physiotherapy was clinically beneficial for plantar fasciitis related pain in the short term; however, there are serious questions around the internal validity of this RCT. There currently exists insufficient evidence to support the use of KTT over other modalities in clinical practice.

  19. Polytetrafluoroethylene surface modification by filamentary and homogeneous dielectric barrier discharges in air

    International Nuclear Information System (INIS)

    Fang Zhi; Hao Lili; Yang Hao; Xie Xiangqian; Qiu Yuchang; Edmund, Kuffel

    2009-01-01

    In this paper, polytetrafluoroethylene (PTFE) films are modified using non-equilibrium plasma generated by homogeneous DBD in air at medium pressure, and the results are compared to those treated by using filamentary DBD in air at atmospheric pressure. The surface properties of PTFE films before and after the treatments are studied using contact angle and surface energy measurement, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). It is found that the plasma treatments modify the PTFE surface in both morphology and composition. The PTFE films modified in both treatments show a remarkable decrease in water contact and a remarkable increase in surface energy. XPS analysis reveals that oxygen-containing polar groups are introduced onto the PTFE surface, and SEM analysis shows that the surfaces of the films are etched after both the treatments. It is found that homogeneous DBD is more effective in PTFE surface modification than filamentary DBD as it can make the contact angle decline to a lower level by introducing more oxygen-containing groups, and the possible reason for this effect is discussed.

  20. Liberação de componentes do extrato de Casearia sylvestris Swartz empregando membranas de látex natural como suporte

    Directory of Open Access Journals (Sweden)

    Alberto Trecco

    2014-01-01

    Full Text Available A membrana de látex natural (NRL – Natural Rubber Latex, manipulada a partir do látex extraído da seringueira Hevea brasiliensis, tem apresentado grande potencial de aplicação no campo da biomedicina e dos biomateriais. Graças a sua biocompatibilidade e baixa taxa de rejeição, ela tem sido utilizada para próteses e enxertos, atuando como estimulante da angiogênese, adesão celular e barreira física a agentes infecciosos. Além dessas aplicações, as membranas são utilizadas como matriz de sistemas de liberação para avaliar o comportamento da liberação de fármacos e extratos de origem vegetal que apresentam propriedades medicinais. O sistema extrato-membrana tem como objeto de estudo uma nova abordagem dessas substâncias no tratamento de feridas visando à cicatrização e regeneração do tecido envolvido. Casearia sylvestris, conhecida popularmente como guaçatonga, pertence à família Salicaceae, conhecida na medicina popular pelos seus efeitos antiulcerogênicos, cicatrizantes, antiofídicos, anti-inflamatórios e antissépticos, propriedades já comprovadas por estudos. Trabalhos recentes demonstraram que a liberação controlada de fármacos e extratos utilizando membranas de látex natural é uma alternativa interessante e promissora para aplicações biomédicas. Assim, o objetivo deste projeto foi estudar a liberação do extrato de Casearia sylvestris incorporado à membrana de látex em soluções com diferentes valores de pH, com o propósito de estudar seu comportamento e sua liberação de forma controlada. A taxa de liberação do extrato do sistema extrato-membrana foi monitorada e analisada utilizando-se o método de espectroscopia ótica (UV. O pH básico age desestabilizando a membrana indicando que o polímero possui a habilidade de proteger o extrato de ser liberado em valores de pH ácidos, direcionando sua aplicação para o sítio de melhor absorção. Além disso, a liberação segue uma função bi

  1. Evaluation of texaphyrins as tumor selective radiation sensitizers

    International Nuclear Information System (INIS)

    Qing Fan; Woodburn, Kathryn W.; Young, Stuart W.

    1997-01-01

    Texaphyrins are expanded porphyrin macrocycles that selectively localize and are retained in cancerous lesions. The function of the texaphyrin can be manipulated by the incorporation of different metal ions into the macrocycle's central cavity. Gadolinium texaphyrin (Gd-Tex) and lutetium texaphyrin (Lu-Tex) were evaluated as radiation sensitizers. Radiation sensitization studies were performed using SMT-F and EMT6 mammary tumor-bearing mice. Single and multifraction dose regimens were performed. SMT-F bearing DBA/2N mice and EMT6 bearing Balb/c mice were intravenously administered with Gd-Tex of Lu-Tex (5-40 μmol/kg) 30 minutes to 5 hours prior to radiation (10-50 Gray) for the single fraction studies. The more radioresistant EMT-6 sarcoma model was used for the multifraction studies. The tumor bearing animals were injected with Gd-Tex (5, 20, or 40 μmol/kg) to 2 hours prior radiation (1, 2, or 4 Gray), this regimen was performed for five consecutive days. Gd-Tex is paramagnetic and has a strong fluorescence signal. Tumor selectivity was determined by MRI and fluorescence spectral imaging before and up to 24 hours following the administration of Gd-Tex. Gd-Tex but not Lu-Tex, proved to be an effective radiation sensitizer. Administration of Gd-Tex (40 μmol/kg) prior to a single dose of 30 Gray radiation provided a significant improvement in survival in SMT-F-bearing DBA/2N mice as compared to animals receiving radiation alone (p = 0.0034). A significant radiation sensitization effect was also found in multiple fraction studies (five consecutive days) with Balb/C mice bearing EMT-6 neoplasma-- following 1 Gray of radiation for 5 days there was a significant difference between the 20 and 40 μmol/kg group and controls (p = 0.003, p = 0.005 respectively). MRI and fluorescence spectral imaging studies of tumor bearing animals revealed excellent contrast enhancement of the tumor which persisted up to 24 hours. Texaphyrins localize in neoplasms as visualized using MRI

  2. Adhesive and morphological characteristics of surface chemically modified polytetrafluoroethylene films

    International Nuclear Information System (INIS)

    Hopp, B.; Kresz, N.; Kokavecz, J.; Smausz, T.; Schieferdecker, H.; Doering, A.; Marti, O.; Bor, Z.

    2004-01-01

    In the present paper, we report an experimental determination of adhesive and topographic characteristics of chemically modified surface of polytetrafluoroethylene (PTFE) films. The surface chemistry was modified by ArF excimer laser irradiation in presence of triethylene-tetramine photoreagent. The applied laser fluence was varied in the range of 0.4-9 mJ/cm 2 , and the number of laser pulses incident on the same area was 1500. To detect the changes in the adhesive features of the treated Teflon samples, we measured receding contact angle for distilled water and adhesion strength, respectively. It was found that the receding contact angle decreased from 96 deg. to 30-37 deg. and the adhesion strength of two-component epoxy glue to the treated sample surface increased from 0.03 to 9 MPa in the applied laser fluence range. Additionally, it was demonstrated that the adhesion of human cells to the modified Teflon samples is far better than to the untreated ones. The contact mode and pulsed force mode atomic force microscopic investigations of the treated samples demonstrated that the measured effective contact area of the irradiated films does not differ significantly from that of the original films, but the derived adhesion force is stronger on the modified samples than on the untreated ones. Hence, the increased adhesion of the treated Teflon films is caused by the higher surface energy

  3. The taphonomy of a remarkable leaf bed assemblage from the Late Oligocene-Early Miocene Gore Lignite Measures, southern New Zealand

    Energy Technology Data Exchange (ETDEWEB)

    Ferguson, David K.; Zetter, Reinhard; Vavra, Norbert [Department of Paleontology, University of Vienna, Althanstrasse 14, A-1090 Vienna (Austria); Lee, Daphne E. [Department of Geology, University of Otago, PO Box 56, Dunedin (New Zealand); Bannister, Jennifer M. [Department of Botany, University of Otago, PO Box 56, Dunedin (New Zealand); Jordan, Gregory J. [School of Plant Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001 (Australia); Mildenhall, Dallas C. [GNS Science, PO Box 30-368, Lower Hutt (New Zealand)

    2010-08-01

    A diverse assemblage of fossil leaves showing cellular detail is reported from the Late Oligocene-Early Miocene Gore Lignite Measures, southern New Zealand. The leaf-remains include at least five conifers, such as the genera Agathis, Dacrycarpus, Phyllocladus and Dacrydium, as well as a number of angiosperms including Gymnostoma, Nothofagus Subgenus Brassospora, Phormium, Proteaceae, Sapindaceae and Ericaceae. A parallel palynological study has identified a number of the same elements. The leaf layers represent litter horizons laid down in pools on the surface of a subtropical ombrotrophic forest mire that formed on an extensive low-lying coastal plain. Highly acidic water ponded in tree-fall depressions prevented microbial decay of the foliage. Taxa represented by both leaves and pollen are considered to have been components of the autochthonous swamp forest. Some other pollen grains are thought to represent local elements, based on the pollination biology of their nearest living relatives. Other taxa whose extant representatives are wind-pollinated may have grown further away. (author)

  4. Manufacturing Technology of Composite Materials-Principles of Modification of Polymer Composite Materials Technology Based on Polytetrafluoroethylene.

    Science.gov (United States)

    Panda, Anton; Dyadyura, Kostiantyn; Valíček, Jan; Harničárová, Marta; Zajac, Jozef; Modrák, Vladimír; Pandová, Iveta; Vrábel, Peter; Nováková-Marcinčínová, Ema; Pavelek, Zdeněk

    2017-03-31

    The results of the investigations into the technological formation of new wear-resistant polymer composites based on polytetrafluoroethylene (PTFE) filled with disperse synthetic and natural compounds are presented. The efficiency of using PTFE composites reinforced with carbon fibers depends on many factors, which influence the significant improvement of physicomechanical characteristics. The results of this research allow stating that interfacial and surface phenomena of the polymer-solid interface and composition play a decisive role in PTFE composites properties. Fillers hinder the relative movement of the PTFE molecules past one another and, in this way, reduce creep or deformation of the parts, reducing the wear rate of parts used in dynamic applications as well as the coefficient of thermal expansion. The necessary structural parameters of such polymer composites are provided by regimes of process equipment.

  5. Studies on surface modification of poly(tetrafluoroethylene) film by remote and direct Ar plasma

    International Nuclear Information System (INIS)

    Wang Chen; Chen Jierong; Li Ru

    2008-01-01

    Poly(tetrafluoroethylene) (PTFE) surfaces are modified with remote and direct Ar plasma, and the effects of the modification on the hydrophilicity of PTFE are investigated. The surface microstructures and compositions of the PTFE film were characterized with the goniometer, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Results show that the remote and direct plasma treatments modify the PTFE surface in morphology and composition, and both modifications cause surface oxidation of PTFE films, in the forming of some polar functional groups enhancing polymer wettability. When the remote and direct Ar plasma treats PTFE film, the contact angles decrease from the untreated 108-58 o and 65.2 o , respectively. The effect of the remote Ar plasma is more noticeable. The role of all kinds of active species, e.g. electrons, ions and free radicals involved in plasma surface modification is further evaluated. This shows that remote Ar plasma can restrain the ion and electron etching reaction and enhance radical reaction

  6. Intrasellar Iatrogenic Carotid Pseudoaneurysm: Endovascular Treatment with a Polytetrafluoroethylene-Covered S tent

    International Nuclear Information System (INIS)

    Vanninen, R. L.; Manninen, H. I.; Rinne, J.

    2003-01-01

    This case illustrates successful treatment of a large postoperative intrasellar pseudoaneurysm with a polytetrafluoroethylene (PTFE)-covered stent. The advantages and potential disadvantages of this novel method of treatment are discussed. A previously healthy 59-year-old man underwent transsphenoidal operative treatment for hypophyseal macroadenoma,complicated by bleeding. On the 17 th postoperative day the patient had profuse arterial bleeding from his nose requiring posterior tamponade. Subsequent angiography of the left internal carotid artery(ICA) revealed a large pseudoaneurysm located intrasellarly, with the orifice in the anteromedial wall in the ophthalmic segment of the ICA.Surgical treatment of the pseudoaneurysm was considered very risky. A12-mm PTFE-covered stent (JoMed, Ulestraten, Netherlands), manually compressed on a PTCA-balloon (Maxxum 4.5/13 mm, Boston Scientific,Ireland) was endovascularly delivered covering the orifice of the pseudoaneurysm. Control angiography immediately after the intervention and one year later revealed no flow into the pseudoaneurysm and the ICA was fully patent. In conclusion, deployment of a PTFE-covered stent proved to be feasible and successful in the treatment of an intrasellariatrogenic ICA pseudoaneurysm. Adequate anticoagulative treatment after the procedure is essential to prevent thrombotic complications

  7. Long term results of polytetrafluoroethylene in above knee femoropopliteal bypass for critical ischaemia.

    LENUS (Irish Health Repository)

    Kavanagh, E G

    2012-02-03

    Ninety-six consecutive above-knee femoropopliteal bypasses, using polytetrafluoroethylene (PTFE) preferentially, were performed for limb-threatening ischaemia. Cumulative primary graft patency was 68 per cent, 49 per cent and 36 per cent and limb salvage 93 per cent, 85 per cent and 75 per cent at 1, 3 and 5 yr respectively. As a result of poor long term survival (51 per cent at 5 yr), and the healing of remedial lesions before graft occlusion, 68 patients (72 per cent) required no further intervention. Eighteen secondary bypasses were undertaken, 12 using ipsilateral saphenous vein. In this group of elderly patients with poor life expectancy, where a limited operation is desirable, the use of PTFE provided excellent limb salvage with low morbidity. Although we can no longer justify our continued use of PTFE in every case of critical ischaemia because of its inferior patency to autogenous vein, we continue to use it preferentially in patients whose lifespan is likely to be short and in cases where a remedial lesion is present.

  8. ExpandED Options: Learning beyond High School Walls

    Science.gov (United States)

    ExpandED Schools, 2014

    2014-01-01

    Through ExpandED Options by TASC, New York City high school students get academic credit for learning career-related skills that lead to paid summer jobs. Too many high school students--including those most likely to drop out--are bored or see classroom learning as irrelevant. ExpandED Options students live the connection between mastering new…

  9. Cell adhesion and proliferation on poly(tetrafluoroethylene) with plasma-metal and plasma-metal-carbon interfaces

    Science.gov (United States)

    Reznickova, Alena; Kvitek, Ondrej; Kolarova, Katerina; Smejkalova, Zuzana; Svorcik, Vaclav

    2017-06-01

    The aim of this article is to investigate the effect of the interface between plasma activated, gold and carbon coated poly(tetrafluoroethylene) (PTFE) on in vitro adhesion and spreading of mouse fibroblasts (L929). Surface properties of pristine and modified PTFE were studied by several experimental techniques. The thickness of a deposited gold film is an increasing function of the sputtering time, conversely thickness of carbon layer decreases with increasing distance between carbon source and the substrate. Because all the used surface modification techniques take place in inert Ar plasma, oxidized degradation products are formed on the PTFE surface, which affects wettability of the polymer surface. Cytocompatibility tests indicate that on samples with Au/C interface, the cells accumulate on the part of sample with evaporated carbon. Number of L929 cells proliferated on the studied samples is comparable to tissue culture polystyrene standard.

  10. Provenance of tetraether membrane lipids in a large temperate lake (Loch Lomond, UK): implications for glycerol dialkyl glycerol tetraether (GDGT)-based palaeothermometry

    NARCIS (Netherlands)

    Buckles, L.K.; Weijers, J.W.H.; Tran, X.-M.; Waldron, S.; Sinninghe Damsté, J.S.

    2014-01-01

    The application of glycerol dialkyl glycerol tetraether (GDGT)-based palaeoenvironmental proxies, such as the branched vs. isoprenoidal tetratether (BIT) index, TEX86 and the MBT–CBT palaeothermometer, has lately been expanded to lacustrine sediments. Given recent research identifying the production

  11. Provenance of tetraether membrane lipids in a large temperate lake (Loch Lomond, UK) : Implications for glycerol dialkyl glycerol tetraether (GDGT)-based palaeothermometry

    NARCIS (Netherlands)

    Buckles, L. K.; Weijers, J. W H; Tran, X.-M.; Waldron, S.; Sinninghe Damsté, J. S.

    2014-01-01

    The application of glycerol dialkyl glycerol tetraether (GDGT)-based palaeoenvironmental proxies, such as the branched vs. isoprenoidal tetratether (BIT) index, TEX86 and the MBT-CBT palaeothermometer, has lately been expanded to lacustrine sediments. Given recent research identifying the production

  12. Removal of retrievable self-expandable urethral stents: experience in 58 stents

    International Nuclear Information System (INIS)

    Shin, Ji Hoon; Song, Ho-Young; Kim, Jin Hyoung; Ko, Heung-Kyu; Kim, Yong Jae; Woo, Chul-Woong; Kim, Tae-Hyung; Ko, Gi-Young; Yoon, Hyun-Ki; Sung, Kyu-Bo; Park, Hyungkeun

    2006-01-01

    The purpose of this study was to retrospectively evaluate the safety and efficacy of removing retrievable self-expandable urethral stents using a retrieval hook wire. Under fluoroscopic guidance, the removal of 58 polyurethane or PTFE (polytetrafluoroethylene)-covered stents was attempted in 33 patients using a retrieval hook wire. Indications for removal were elective removal (n=21), stent migration (n=19), formation of tissue hyperplasia around or inside of the stent (n=14), stent deformity (n=3), and severe pain (n=1). The mean time the stents remained in place was 64.8±42.9 days (range, 1-177 days). Fifty-six (97%) of the 58 stents were successfully removed using the retrieval hook wire despite the following difficulties; hook wire disconnection (n=2), untied drawstrings (n=3), and polyurethane membrane disruption/separation (n=4). The removal procedure using a retrieval hook wire failed in two stents (3%) which had migrated into the urinary bladder. One of the two stents with migration into the urinary bladder was removed using a snare through the cystostomy route. The overall complication rate was 14% (seven hematuria cases and one urethral tear case), and all were minor and spontaneously resolved without further treatment. In conclusion, removal of retrievable urethral stents using a retrieval hook wire was safe and effective despite some technical difficulties. It is a useful method for allowing temporary stent placement and solving various complications of stent use. (orig.)

  13. Removal of retrievable self-expandable urethral stents: experience in 58 stents

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Ji Hoon; Song, Ho-Young; Kim, Jin Hyoung; Ko, Heung-Kyu; Kim, Yong Jae; Woo, Chul-Woong; Kim, Tae-Hyung; Ko, Gi-Young; Yoon, Hyun-Ki; Sung, Kyu-Bo [Asan Medical Center, Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Seoul (Korea); Park, Hyungkeun [Asan Medical Center, Department of Urology, University of Ulsan College of Medicine, Seoul (Korea)

    2006-09-15

    The purpose of this study was to retrospectively evaluate the safety and efficacy of removing retrievable self-expandable urethral stents using a retrieval hook wire. Under fluoroscopic guidance, the removal of 58 polyurethane or PTFE (polytetrafluoroethylene)-covered stents was attempted in 33 patients using a retrieval hook wire. Indications for removal were elective removal (n=21), stent migration (n=19), formation of tissue hyperplasia around or inside of the stent (n=14), stent deformity (n=3), and severe pain (n=1). The mean time the stents remained in place was 64.8{+-}42.9 days (range, 1-177 days). Fifty-six (97%) of the 58 stents were successfully removed using the retrieval hook wire despite the following difficulties; hook wire disconnection (n=2), untied drawstrings (n=3), and polyurethane membrane disruption/separation (n=4). The removal procedure using a retrieval hook wire failed in two stents (3%) which had migrated into the urinary bladder. One of the two stents with migration into the urinary bladder was removed using a snare through the cystostomy route. The overall complication rate was 14% (seven hematuria cases and one urethral tear case), and all were minor and spontaneously resolved without further treatment. In conclusion, removal of retrievable urethral stents using a retrieval hook wire was safe and effective despite some technical difficulties. It is a useful method for allowing temporary stent placement and solving various complications of stent use. (orig.)

  14. Temporary suspension of acute facial paralysis using the S-S Cable Suture (Medical U&A, Tokyo, Japan).

    Science.gov (United States)

    Ozaki, Mine; Takushima, Akihiko; Momosawa, Akira; Kurita, Masakazu; Harii, Kiyonori

    2008-07-01

    For a treatment of facial paralysis, suture suspension of soft tissue is considered effective due to its less invasiveness and relatively simple technique, with minimal bruising and rapid recovery. However, suture suspension effect may not last for a long period of time. We obtained good outcome with temporary static suture suspension in 5 cases of severe facial paralysis in the intervening period between the onset of paralysis and expected spontaneous recovery. We used the S-S Cable Suture (Medical U&A, Tokyo, Japan), which was based on the modification of previously established method using the Gore-Tex cable suture originally reported by Sasaki et al in 2002. Because of the ease of technique and relatively strong lifting capability of the malar pad, we recommend it as a useful procedure for a patient suffering acute facial paralysis with possible spontaneous recovery for an improved quality of life by the quick elimination of facial distortion.

  15. Successful Endovascular Treatment of a Left Common Carotid Artery Aneurysm Following Failed Surgery of a Right Common Carotid Artery Aneurysm

    International Nuclear Information System (INIS)

    Cil, Barbaros E.; Ucar, Ibrahim; Ozsoy, Fatma; Arat, Anil; Yorgancioglu, Cem; Boeke, Erkmen

    2005-01-01

    Aneurysm of the common carotid artery is a rare and serious disease requiring prompt treatment in order to avoid neurologic complications. A 39-year-old man presented with voice impairment and a pulsatile mass at the right side of his neck and was found by color Doppler examination to have bilateral common carotid artery aneurysms of unknown origin. The right-sided large aneurysm was treated with placement of an 8 mm interposition Gore-Tex graft between the right common and internal carotid arteries. The surgical graft thrombosed 7 days after the surgery but the left-sided aneurysm was successfully treated by a Jostent peripheral stent-graft. Color Doppler examination showed a patent stent and no filling of the aneurysm on his first and sixth-month follow-up. Bilateral common carotid artery aneurysm is an exceptionally unusual condition and endovascular treatment of carotid artery aneurysms with covered stents may become an effective treatment alternative for these lesions

  16. Internal and External Flow over Laser-Textured Superhydrophobic Polytetrafluoroethylene (PTFE).

    Science.gov (United States)

    Ahmmed, K M Tanvir; Patience, Christian; Kietzig, Anne-Marie

    2016-10-12

    In this work, internal and external flows over superhydrophobic (SH) polytetrafluoroethylene (PTFE) were studied. The SH surface was fabricated by a one-step femtosecond laser micromachining process. The drag reduction ability of the textured surface was studied experimentally both in microscale and macroscale internal flows. The slip length, which indicates drag reduction in fluid flow, was determined in microscale fluid flow with a cone-and-plate rheometer, whereas a pressure channel setup was used for macroscale flow experiments. The textured PTFE surface reduced drag in both experiments yielding comparable slip lengths. Moreover, the experimentally obtained slip lengths correspond well to the result obtained applying a semianalytical model, which considers the solid fraction of the textured surface. In addition to the internal flow studies, we fabricated SH PTFE spheres to test their drag reduction abilities in an external flow experiment, where the terminal velocities of the falling spheres were measured. These experiments were conducted at three different Reynolds numbers in both viscous and inertial flow regimes with pure glycerol, a 30% glycerol solution, and water. Surprisingly, the drag on the SH spheres was higher than the measured drag on the non-SH spheres. We hypothesize that the increase in form drag outweighs the decrease in friction drag on the SH sphere. Thus, the overall drag increased. These experiments demonstrate that a superhydrophobic surface that reduces drag in internal flow might not reduce drag in external flow.

  17. A proton-exchange membrane prepared by the radiation grafting of styrene and silica into polytetrafluoroethylene films

    Science.gov (United States)

    Yu, Hongyan; Shi, Jianheng; Zeng, Xinmiao; Bao, Mao; Zhao, Xinqing

    2009-07-01

    A polytetrafluoroethylene (PTFE) based organic-inorganic hybrid proton-exchange membrane was prepared from simultaneous radiation grafting of styrene (St) into porous PTFE membrane with the in situ sol-gel reaction of tetraethoxysilane (TEOS) followed by sulfonation in fuming sulfonic acid. The effect of radiation on the sol-gel reaction was studied. The results show that radiation promotes the sol-gel reaction with the help of St at room temperature. Incorporated silica gel helps to produce higher degree of grafting (DOG). SEM analysis was conducted to confirm that the inorganic silicon oxide was introduced to produce hybrid membrane in this work. The proton conductivity of membrane evaluated using electrochemical impedance spectroscopy is much higher (14.3×10 -2 S cm -1) than that of Nafion ® 117 at temperature of 80 °C with acceptable water uptake 51 wt%.

  18. Manufacturing Technology of Composite Materials—Principles of Modification of Polymer Composite Materials Technology Based on Polytetrafluoroethylene

    Directory of Open Access Journals (Sweden)

    Anton Panda

    2017-03-01

    Full Text Available The results of the investigations into the technological formation of new wear-resistant polymer composites based on polytetrafluoroethylene (PTFE filled with disperse synthetic and natural compounds are presented. The efficiency of using PTFE composites reinforced with carbon fibers depends on many factors, which influence the significant improvement of physicomechanical characteristics. The results of this research allow stating that interfacial and surface phenomena of the polymer–solid interface and composition play a decisive role in PTFE composites properties. Fillers hinder the relative movement of the PTFE molecules past one another and, in this way, reduce creep or deformation of the parts, reducing the wear rate of parts used in dynamic applications as well as the coefficient of thermal expansion. The necessary structural parameters of such polymer composites are provided by regimes of process equipment.

  19. Surgical treatment of pulmonic stenosis in dogs under cardiopulmonary bypass: outcome in nine dogs.

    Science.gov (United States)

    Bristow, P; Sargent, J; Luis Fuentes, V; Brockman, D

    2018-01-01

    To describe the outcome for nine dogs with pulmonic stenosis treated by open patch grafting using expanded polytetrafluoroethylene under cardiopulmonary bypass. Data were collected from the hospital records of all dogs that had undergone right ventricular outflow tract grafting with an expanded polytetrafluoroethylene patch under cardiopulmonary bypass between 2006 and 2012 for the treatment of pulmonic stenosis. Echocardiographic images were reviewed and the pressure gradient across the right ventricular outflow tract re-measured. Owners of dogs still alive at the time of writing were invited to return to the hospital for reassessment. Nine dogs met the inclusion criteria. Median pressure gradient preoperatively was 118 mmHg, (range 102 to 259 mmHg) reducing to a median of 20 mmHg (range 7 to 53 mmHg) at 48 hours postoperatively and 14 mmHg (range 10 to 70 mmHg), with a median percentage reduction of 89% (range 41 to 94%) at long-term follow-up. Eight of nine dogs survived surgery, with six of nine surviving to hospital discharge. Two dogs were still alive over 6 and 8 years postoperatively. No long-term deaths were believed to be attributable to pulmonic stenosis. Expanded polytetrafluoroethylene patch grafting of the right ventricular outflow tract for treatment of severe pulmonic stenosis in dogs is feasible and can be an effective method to reduce the severity of right ventricular outflow tract obstruction. © 2017 British Small Animal Veterinary Association.

  20. Insensitive high-energy energetic structural material of tungsten-polytetrafluoroethylene-aluminum composites

    Directory of Open Access Journals (Sweden)

    Liu Wang

    2015-11-01

    Full Text Available Energetic structural material is a kind of materials that are inert under normal conditions but could produce exothermic chemical reaction when subjected to impact. This report shows a kind of energetic structural material of tungsten (W-polytetrafluoroethylene (PTFE-aluminum (Al with density of 4.12 g/cm3, excellent ductility and dynamic compressive strength of 96 MPa. Moreover, 50W-35PTFE-15Al (wt% can exhibit a high reaction energy value of more than 2 times of TNT per unit mass and 5 times of TNT per unit volume, respectively, but with excellent insensitivity compared with traditional explosives. Under thermal conditions, the W-PTFE-Al composite can keep stable at 773 K. Under impact loading, when the strain rate up to ∼4820 s−1 coupled with the absorbed energy per unit volume of 120 J/cm3, deflagration occurs and combustion lasts for 500 μs. During impact compressive deformation, the PTFE matrix is elongated into nano-fibers, thus significantly increases the reaction activity of W-PTFE-Al composites. The nano-fiber structure is necessary for the reaction of W-PTFE-Al composites. The formation of PTFE nano-fibers must undergo severe plastic deformation, and therefore the W-PTFE-Al composites exhibit excellent insensitivity and safety. Furthermore, the reaction mechanisms of W-PTFE-Al composites in argon and in air are revealed.

  1. Synthesis of a gamma irradiation grafted polytetrafluoroethylene (PTFE) based olefinic copolymer

    International Nuclear Information System (INIS)

    Ferreto, Helio Fernando Rodrigues

    2006-01-01

    The extrusion of linear low density polyethylene (LLDPE) is limited by a process related defect known as 'melt fracture' or 'sharkskin', which is a surface defect of the extruded polymer. This defect results in a product with a rough surface that lacks luster and in alterations of specific surface properties. The aim of this study was to obtain a recycled polytetrafluoroethylene polymer with an olefin that could improve the extrudability of the LLDPE. The copolymer was obtained by irradiating recycled PTFE in an inert atmosphere followed by the addition of an olefinic monomer to graft the latter in the polymeric matrix (PTFE). After a certain time of contact, the copolymer was heat treated to permit recombination and elimination of the radicals, both in a reactive and/or inert atmosphere. Three olefinic monomers were used, namely; acetylene, ethylene and 1,3-butadiene. The 1,3-butadiene monomer was found to be more effective with respect to grafting. The specimens were studied using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential thermogravimetry (DTG). 0.2-2.0 wt% of the copolymer that was obtained was mixed with LLDPE. The rheological properties of the mixture were determined with a torque rheometer. The results indicated that the process used rendered a copolymer which when added to LLDPE, improved the extrusion process and eliminated the defect 'melt fracture'. (author)

  2. Alergia ao látex em paciente com síndrome de Kabuki: relato de caso Alergia al látex en paciente con síndrome de Kabuki: relato de caso Latex allergy in a patient with Kabuki syndrome: case report

    Directory of Open Access Journals (Sweden)

    Vera Coelho Teixeira

    2010-10-01

    Full Text Available JUSTIFICATIVA E OBJETIVOS: O conhecimento do profissional de Anestesiologia sobre aspectos específicos de pacientes portadores de síndromes raras é uma necessidade crescente, já que cada vez mais esses pacientes são levados aos centros cirúrgicos. O objetivo é descrever um caso de alergia ao látex ocorrido em um desses pacientes com diagnóstico da Síndrome de Kabuki, cujos aspectos ainda não foram completamente esclarecidos, alertando os anestesiologistas quanto à possibilidade dessa associação. RELATO DO CASO: Paciente de 11 anos com diagnóstico de Síndrome de Kabuki foi admitida para exérese de lesões de partes moles. Apresentava histórico de reações alérgicas prévias após procedimentos cirúrgicos de pequeno porte. Com a necessidade da realização de um novo procedimento, após avaliação pré-anestésica, foi encaminhada a um alergologista, que a submeteu a testes cutâneos que confirmaram a hipótese de alergia ao látex. Foi levada mais uma vez ao centro cirúrgico para exérese das lesões, sob anestesia geral. Foram tomadas todas as precauções, com o objetivo de evitar novas manifestações clínicas. O procedimento transcorreu sem intercorrências e a paciente recebeu alta no mesmo dia, sem apresentar qualquer tipo de complicação, o que reforçou ainda mais o diagnóstico. CONCLUSÕES: A Síndrome de Kabuki parece ter um curso relativamente benigno em sua história natural. Entretanto, há muitos aspectos ainda a serem esclarecidos e, portanto, não se descarta a possibilidade da associação dessa patologia com outras condições que interessam ao anestesiologista. Essa descrição tem por objetivo alertar quanto ao risco da associação dessa síndrome com a alergia ao látex. Para tanto, deve-se incentivar, na avaliação pré-anestésica desses pacientes, a realização de uma anamnese bem feita, com a análise de outros fatores predisponentes que não a síndrome per seJUSTIFICATIVA Y OBJETIVOS: El

  3. Fabrication of TiO2-modified polytetrafluoroethylene ultrafiltration membranes via plasma-enhanced surface graft pretreatment

    Science.gov (United States)

    Qian, Yingjia; Chi, Lina; Zhou, Weili; Yu, Zhenjiang; Zhang, Zhongzhi; Zhang, Zhenjia; Jiang, Zheng

    2016-01-01

    Surface hydrophilic modification of polymer ultrafiltration membrane using metal oxide represents an effective yet highly challenging solution to improve water flux and antifouling performance. Via plasma-enhanced graft of poly acryl acid (PAA) prior to coating TiO2, we successfully fixed TiO2 functional thin layer on super hydrophobic polytetrafluoroethylene (PTFE) ultrafiltration (UF) membranes. The characterization results evidenced TiO2 attached on the PTFE-based UF membranes through the chelating bidentate coordination between surface-grafted carboxyl group and Ti4+. The TiO2 surface modification may greatly reduce the water contact angle from 115.8° of the PTFE membrane to 35.0° without degradation in 30-day continuous filtration operations. The novel TiO2/PAA/PTFE membranes also exhibited excellent antifouling and self-cleaning performance due to the intrinsic hydrophilicity and photocatalysis properties of TiO2, which was further confirmed by the photo-degradation of MB under Xe lamp irradiation.

  4. Torsional Tribological Behavior and Torsional Friction Model of Polytetrafluoroethylene against 1045 Steel

    Science.gov (United States)

    Wang, Shibo; Niu, Chengchao

    2016-01-01

    In this work, the plane-on-plane torsional fretting tribological behavior of polytetrafluoroethylene (PTFE) was studied. A model of a rigid, flat-ended punch acting on an elastic half-space was built according to the experimental conditions. The results indicate that the shape of T–θ curves was influenced by both the torsional angle and the normal load. The torsion friction torque and wear rate of PTFE exponentially decreased when the torsion angle rose. The torsional torque increased from 0.025 N·m under a normal load of 43 N to 0.082 N·m under a normal load of 123 N. With sequentially increasing normal load, the value of torque was maintained. With rising normal load, the wear mass loss of PTFE disks was increased and the wear rate was decreased. Good agreement was found with the calculated torque according to the model and the experimental torque except for that under a normal load of 163 N. The difference under a normal load of 163 N was caused by the coefficient of friction. Usually the coefficient of friction of a polymer decreases with increasing normal load, whereas a constant coefficient of friction was applied in the model. PMID:26799324

  5. Full four-dimensional and reciprocal Mueller matrix bidirectional reflectance distribution function of sintered polytetrafluoroethylene.

    Science.gov (United States)

    Germer, Thomas A

    2017-11-20

    We measured the Mueller matrix bidirectional reflectance distribution function (BRDF) of a sintered polytetrafluoroethylene (PTFE) sample over the scattering hemisphere for six incident angles (0°-75° in 15° steps) and for four wavelengths (351 nm, 532 nm, 633 nm, and 1064 nm). The data for each wavelength were fit to a phenomenological description for the Mueller matrix BRDF, which is an extension of the bidirectional surface scattering modes developed by Koenderink and van Doorn [J. Opt. Soc. Am. A.15, 2903 (1998)JOAOD60740-323210.1364/JOSAA.15.002903] for unpolarized BRDF. This description is designed to be complete, to obey the appropriate reciprocity conditions, and to provide a full description of the Mueller matrix BRDF as a function of incident and scattering directions for each wavelength. The description was further extended by linearizing the surface scattering mode coefficients with wavelength. This data set and its parameterization provides a comprehensive on-demand description of the reflectance properties for this commonly used diffuse reflectance reference material over a wide range of wavelengths.

  6. Substituição parcial do pericárdio de cães por membrana de látex natural Partial replacement of dog pericardium with a natural latex membrane

    Directory of Open Access Journals (Sweden)

    Soraya Lopes SADER

    2000-12-01

    Full Text Available FUNDAMENTO: São numerosas as vantagens de se fechar a cavidade pericárdica após as operações cardíacas e pneumonectomias intrapericárdicas. OBJETIVO: Estudar o comportamento da membrana de látex natural como substituto parcial do pericárdio. MATERIAL E MÉTODOS: Em 16 cães, divididos em 3 grupos, ressecou-se um retalho elíptico da porção ântero-lateral esquerda do pericárdio (7 cm x 5 cm: Grupo A (n=4 - o retalho removido foi reimplantado imediatamente; Grupo B (n=8 - o retalho foi substituído por outro, de látex natural, com área equivalente e espessura de 0,3 mm; Grupo C (n=4 - retalho de látex de 0,7 mm de espessura. Em todos os animais, fixou-se o retalho com sutura contínua de fio de polipropileno 5-0 ou 6-0. No último grupo, foram dados 4 pontos adicionais, em U, ancorados em barras de dacron. Realizaram-se eletrocardiogramas (ECG e leucogramas no pré e no pós-operatório, bem como estudo macro e microscópio post-mortem. RESULTADOS: Grupo A - auto-enxerto íntegro, macro e microscopicamente, fortemente aderido ao pulmão e frouxamente aderido ao epicárdio; Grupo B - deiscência parcial da sutura em 1 e total em 2 animais. A membrana de látex não aderiu nem ao pulmão nem ao epicárdio. Em 3 (37,5% animais houve regeneração total e distinta do pericárdio subjacente ao látex, microscopicamente idêntico ao pericárdio nativo. Grupo C - suturas íntegras. Em 3 (75% animais observou-se regeneração pericárdica total e distinta. Nos demais animais dos Grupos B e C, e epicárdio subjacente ao látex apresentava-se ligeiramente espessado, permitindo visibilizar os vasos coronários com facilidade. Microscopicamente, identificaram-se algumas áreas com denso infiltrado linfo-plasmocitário, proliferação fibroblástica e vascular; em outras, os fibroblastos circunscreviam fendas com revestimento mesotelial, indicativas de regeneração irregular do pericárdio. Não se observou infecção local nem alteração do

  7. Comparative study of the monomer grafting: ethylene, acetylene, 1,3-butadiene and estyrene in the matrix of recycled polytetrafluoroethylene (PTFE); Estudo comparativo da enxertia dos monomeros: etileno, acetileno, 1,3-butadieno e estireno na matriz de politetrafluoroetileno (PTFE) reciclado

    Energy Technology Data Exchange (ETDEWEB)

    Ikari, Carolina T.; Rosner, Gerhardyne O.; Oliveira, Ana C.F. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Quimica e Meio Ambiente (CQMA); Faculdades Oswaldo Cruz, Sao Paulo, SP (Brazil); Ferreto, Helio F.R.; Lima, Luiz F.C.P.; Lugao, Ademar B., E-mail: hferreto@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Quimica e Meio Ambiente (CQMA); Moreira, Otavio M. [Faculdades Oswaldo Cruz, Sao Paulo, SP (Brazil)

    2009-07-01

    In this study it is used the recycled polytetrafluoroethylene (PTFE), that with the gamma radiation under inert atmosphere or in presence of air, it is obtained free radicals and a posterior the monomer grafting (ethylene, acetylene, styrene or 1.3 butadiene), obtaining the copolymer polytetrafluoroethylene-g-monomer. It is studied the obtention of the polymer by two methods: by direct way, via grafting, where the polymer is irradiated in presence of monomer, and via grafting when the polymer is irradiated in absence of monomer and under inert or air. The characterization of the copolymer was performed by the techniques of infrared region absorption spectroscopy with Fourier transformation (FTIR), thermogravimetric (TGA) and derivative thermogravimetry (DTG), and percentage of mass grafting (DOG)

  8. Measurements of Extensive Aerosol Optical Properties During TexAQS II: Implications for PM Compliance and Planning

    Science.gov (United States)

    Wright, M. E.; Atkinson, D. B.; Luke, W. T.

    2007-12-01

    In 2000, the Houston-Galveston Area (HGA) was designated as a non-attainment area for several criteria air pollutants by the US EPA. In order to meet the requirements of the federal Clean Air Act, the Second Texas Air Quality Study (TexAQS II) was designed to update the State Implementation Plan (SIP) by providing scientific air quality data over 18 months from June 2005 to October 2006. The data presented here was collected as part of the Texas Radical and Aerosol Measurement Program (TRAMP), a substudy of TexAQS II. Bulk aerosol optical properties were measured for six weeks atop the 60 m high Southwest Moody Tower on the University of Houston campus. The measurements were collected using a cavity ring-down transmissometer/nephelometer (CRDT/N) and consisted of the extensive aerosol coefficients: extinction (bext) at 532 and 1064 nm and scattering (bscat) at 530nm. In addition to daily and whole study averages and calculated mass values, positive correlations between the 1064 nm extinction and 532 nm absorption (babs = bext - bscat) values are displayed for this study period for the first time. Correlation between the particle scattering coefficient and the sum of AMS measured (UNH - PI: R. Griffin) sulfate and organic particle mass concentrations as well as covariance between optical properties and O3, CO and NOx values (ARL/NOAA - PI: W. Luke) are also examined. No correlation is expected between coarse particles (PM10), which are typically primary biogenic suspended soil minerals or windblown dust, and high ozone concentrations. Ozone levels are highest during periods of low wind when coarse particulate is likely to be at a minimum. On the other hand, secondary particles and O3 should be correlated on short time scales because both species tend to have the same precursors, NOx and VOC's, and formation of particles is favored during stagnant conditions. Fine particles (PM2.5) should also correlate with CO since both species have a common emission source. Wind

  9. Guided bone regeneration in rat mandibular defects using resorbable poly(trimethylene carbonate) barrier membranes

    NARCIS (Netherlands)

    van Leeuwen, A. C.; Huddleston Slater, J. J. R.; Gielkens, P. F. M.; de Jong, J. R.; Grijpma, D. W.; Bos, R. R. M.

    The present study evaluates a new synthetic degradable barrier membrane based on poly(trimethylene carbonate) (PTMC) for use in guided bone regeneration. A collagen membrane and an expanded polytetrafluoroethylene (e-PTFE) membrane served as reference materials. In 192 male Sprague-Dawley rats, a

  10. Guided bone regeneration in rat mandibular defects using resorbable poly(trimethylene carbonate) barrier membranes

    NARCIS (Netherlands)

    van Leeuwen, A.C.; Huddelston Slater, J.J.R.; Gielkens, P.F.M.; de Jong, J.R.; Grijpma, Dirk W.; Bos, R.R.M.

    2012-01-01

    The present study evaluates a new synthetic degradable barrier membrane based on poly(trimethylene carbonate) (PTMC) for use in guided bone regeneration. A collagen membrane and an expanded polytetrafluoroethylene (e-PTFE) membrane served as reference materials. In 192 male Sprague–Dawley rats, a

  11. Natural latex graft in lamellar and penetrating sclerectomies in rabbits Enxerto de látex natural na cicatrização de esclerectomias lamelar e penetrante em coelhos

    Directory of Open Access Journals (Sweden)

    Ivia Carmem Talieri

    2009-09-01

    Full Text Available The objective of study was to investigate the effects of natural latex with 0.1% of polylysine on lamellar and penetrating scleroctomies in rabbits. Two groups of twelve rabbits each (lamellar GI and penetrating GII were studied. Scleral square incisions near the limbus were performed on the left eye of each animal. The latex biomembrane was fixed to the recipient sclera and it covered with a conjunctival flap. The clinical evaluations were followed for 60 days. Aplannation tonometry, binocular indirect ophthalmoscopy and slit-lamp biomicroscopy were performed during evaluation. Bright field microscopy and polarization microscopy were employed. Blepharospasm, graft infection, mucoid ocular discharge and chemosis were not observed in either treatment group. The conjunctival hyperemia varied from moderate to hardly noticeable. The postoperative IOP was not statiscally significant, comparing to the preoperative IOP, for GI and GII. The histopathology by polarization microscopy showed that the neoformed tissue was primarily dependent on adjacent vascularized tissues and was constituted by collagen type III. Both groups presented optimum graft adhesion to the receiving sclera. The natural latex biomembrane with 0.1% polylysine constitutes a new alternative for scleral reconstruction. Furthermore, this is a durable material, easy to obtain and manipulate.Este trabalho teve como objetivo investigar os efeitos do látex natural com polilisina a 0,1% na cicatrização de esclerectomias lamelar e penetrante em coelhos. Foram estudados dois grupos de 12 coelhos (GI - lamelar e GII - penetrante. As esclerectomias foram realizadas no olho esquerdo de cada animal. A biomembrana de látex foi fixada à esclera receptora e foi recoberta com conjuntiva bulbar. As avaliações clínicas foram realizadas durante 60 dias. Para tal, empregaram-se a tonometria de aplanação, a oftalmoscopia indireta binocular e a biomicroscopia em lâmpada de fenda. Realizou-se an

  12. Preparation and characterization of semiconductor thin film cells of n-CdSe and CdSel-x Tex. Application in solar cells of liquid union

    International Nuclear Information System (INIS)

    Gutierrez, M.A.

    1987-01-01

    The development of the new energy sources, constitutes one of the most active and changing investigation areas of nowday. Within this frame, the conservation of photovoltaic solar energy, has taken a particular importance, as these systems become directly the photovoltaic solar energy, which incises on a semiconductor, in electric energy. In spite of this advantage, the use of photovoltaic systems is limited, being the main reason for this, the still high cost of the devices. One of the objectives of this Memory is to contribute to the reduction of these photovoltaic devices by using available methods for the preparation of photosensitive material, and for the union formation. The chosen preparation method is the electrochemical one and the electric field is made up in the interphase semiconductor/electrolyte, dipping the semiconductor in a convenient electrolyte. Summarizing, it can be said that the Memory's objetive presented is to discover the experiences realized in the electrochemical preparation of the n-CdSel-x Tex and its characterization by chemical analysis, X-rays difraction, electronic microscope of swept, optical techniques and photoelectrochemical methods. From the data obtained with these techniques, a study of the physical parameters evolution which determine the photovoltaic properties of the semiconductor, is made, as: the concentration of minoritary carriers, ND, and the diffusion length of these carriers, LP. Finally, taking into account the results obtained by the characterization of n-CdSe and CdSel-x Tex, is made from the construction of the photoelectrochemical cell, using two kinds of electrolyte: sulfide- polysulfide ands ferro-ferricyanide. (Author)

  13. Expanded polytetrafluoroethylene membrane alters tissue response to implanted Ahmed glaucoma valve.

    Science.gov (United States)

    DeCroos, Francis Char; Ahmad, Sameer; Kondo, Yuji; Chow, Jessica; Mordes, Daniel; Lee, Maria Regina; Asrani, Sanjay; Allingham, R Rand; Olbrich, Kevin C; Klitzman, Bruce

    2009-07-01

    Long-term intraocular pressure control by glaucoma drainage implants is compromised by the formation of an avascular fibrous capsule that surrounds the glaucoma implant and increases aqueous outflow resistance. It is possible to alter this fibrotic tissue reaction and produce a more vascularized and potentially more permeable capsule around implanted devices by enclosing them in a porous membrane. Ahmed glaucoma implants modified with an outer 5-microm pore size membrane (termed porous retrofitted implant with modified enclosure or PRIME-Ahmed) and unmodified glaucoma implants were implanted into paired rabbit eyes. After 6 weeks, the devices were explanted and subject to histological analysis. A tissue response containing minimal vascularization, negligible immune response, and a thick fibrous capsule surrounded the unmodified Ahmed glaucoma implant. In comparison, the tissue response around the PRIME-Ahmed demonstrated a thinner fibrous capsule (46.4 +/- 10.8 microm for PRIME-Ahmed versus 94.9 +/- 21.2 microm for control, p vascularized near the tissue-material interface. A prominent chronic inflammatory response was noted as well. Encapsulating the aqueous outflow pathway with a porous membrane produces a more vascular tissue response and thinner fibrous capsule compared with a standard glaucoma implant plate. Enhanced vascularity and a thinner fibrous capsule may reduce aqueous outflow resistance and improve long-term glaucoma implant performance.

  14. Latex production with depolymerizing compounds of actin cytoskeleton in rubber trees Produção de látex estimulada pela aplicação de compostos despolimerizantes de citoesqueleto de actina em seringueiras

    Directory of Open Access Journals (Sweden)

    Gao Zheng-Quan

    2008-02-01

    Full Text Available The objective of this work was to assess stimulated latex flow from rubber trees (Hevea brasiliensis with saturated macrolide (latrunculin A, 1, 5, and 10% potassium iodide in 2% methylcellulose compared with 0.3% ethylene in 2% methylcellulose (check and 2% methylcellulose (blank. Latex output and contents of pure rubber, total solid, sucrose, inorganic phosphorus, thiol, and Mg2+ were measured. The treatments containing 1% KI or saturated macrolide increased latex yields compared to the blank with 2% methylcellulose alone. The 1% KI or saturated macrolide treatments were equal to that of 0.3% ethylene check treatment. However, 5 and 10% KI were harmful to bark of rubber trees, even caused prolonged tapping panel dryness.O objetivo deste trabalho foi avaliar a produção de látex em seringueiras (Hevea brasiliensis estimulada pela aplicação de macrolídeo saturado (latrunculina A, iodeto de potássio a 1, 5 e 10%, e etileno a 0,3%, preparados em solução de metilcelulose a 0,2%. O tratamento testemunha consistiu da aplicação de solução pura de metilcelulose a 2%. Foram medidos a produção de látex e o conteúdo de borracha pura, sólidos totais, sacarose, fósforo inorgânico, tiol e Mg2+. A aplicação de KI a 1% ou de macrolídeo saturado aumentou a produção de látex em comparação com o tratamento testemunha. Os tratamentos com KI a 1% e macrolídeo saturado foram iguais ao tratamento com etileno a 0,3%. No entanto, os tratamentos com KI a 5 e 10% foram prejudiciais à casca da seringueira, causando até mesmo o secamento do painel-de-sangria.

  15. Studies on surface grafting of AAc/SSS binary monomers onto polytetrafluoroethylene by dielectric barrier discharge initiation

    International Nuclear Information System (INIS)

    Xi Zhenyu; Xu Youyi; Zhu Liping; Liu Fu; Zhu Baoku

    2008-01-01

    Polytetrafluoroethylene (PTFE) films were pre-treated by dielectric barrier discharge in atmospheric pressure with air as carrier gas. And then the hydrophilic sulfonate groups were introduced by the single step grafting method with binary monomer solution of acrylic acid (AAc) and sodium 4-styrenesulfonate (SSS). The effects of binary monomer ratio, reaction solution concentration and polymerization time on the degree of grafting were investigated. The surface chemical change was determined by Fourier transform infrared attenuated total reflection spectroscopy (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS). Morphological changes on the film surface were described using field emitting scanning electron microscopy (SEM) and atomic force microscopy (AFM). The surface hydrophilicity of the modified film was characterized through water contact angle measurement. It was found that the water contact angle of the film surface reduced significantly when compared with the original one, indicating the introduction of hydrophilic groups and improvement of the surface hydrophilicity

  16. Tissue expander infections in children: look beyond the expander pocket.

    Science.gov (United States)

    Mason, A C; Davison, S P; Manders, E K

    1999-11-01

    Infection of the expander pocket is the most common complication encountered with soft-tissue expansion. It is usually due to direct inoculation with skin flora either at the time of expander insertion or from extrusion of the device. The authors report two cases of infection of tissue expanders in which the children had concomitant infected sites distant from the prosthesis. Etiological bacteria of common pediatric infections like otitis media and pharyngitis were cultured from the infected expander pocket, raising suspicion that translocation of the organism to the expander had occurred. Aggressive antibiotic treatment, removal of the prosthesis, and flap advancement is advocated.

  17. Plasma-Functionalized Polytetrafluoroethylene Nanoparticles for Improved Wear in Lubricated Contact

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Vinay [Materials Science; Timmons, Richard [Chemistry and Biochemistry, University of Texas at Arlington, P.O. Box 19065, Arlington, Texas 76019, United States; Erdemir, Ali [Argonne National Lab, Argonne, Illinois 60439, United States; Aswath, Pranesh B. [Materials Science

    2017-07-20

    Plasma-functionalized polytetrafluoroethylene (PTFE) nanoparticles were employed to evaluate their utility in improving the lubrication property of a group III mineral oil with a significantly low amount of zinc dialkyl dithiophosphate (ZDDP). The particles were coated with two consecutive films; the initial coating contained silica to enhance amorphous glassy tribofilm formation, followed by a methacrylate film to protect the silica coating and enhance dispersibility in the oil. The functionalized nanoparticles were evaluated for their tribological performance using a high-frequency reciprocating rig, in a cylinder-on-flat configuration. The oil formulations containing ZDDP (350 ppm phosphorus level) and the functionalized nanoparticles resulted in dramatic reductions in the friction coefficient and overall wear compared to the samples containing nonfunctionalized PTFE nanoparticles, ZDDP (350 ppm P), and samples devoid of nanoparticles but containing ZDDP with a 700 ppm P treat rate. XPS and XANES spectroscopy were employed to characterize the tribological films formed on the test samples. The samples with functionalized particles and ZDDP clearly exhibited tribofilms with Si- and F-doped polyphosphates of Zn coupled with the presence of ZnS at the metal-tribofilm interface. On the other hand, oils without the functionalized nanoparticles have oxides of Fe and to a lesser extent short-chain phosphates of Zn. The overall results suggest that the synergism between plasma-coated PTFE nanoparticles and ZDDP contributed to the development of protective tribofilms even at reduced amount of phosphorus in the oil. This new method of employing nanoparticles to deliver novel antifriction and antiwear chemistries at the tribological interfaces stands out as a promising approach to further reduce P levels in oils without compromising friction and wear performance.

  18. Intraarterial 9-beta-methyl carbacyclin improves canine polytetrafluoroethylene graft patency

    International Nuclear Information System (INIS)

    Dacey, L.J.; Hees, P.S.; Cronenwett, J.L.

    1988-01-01

    This study examined the effect of 9-beta-methyl carbacyclin, a synthetic, stable prostacyclin analog, on canine polytetrafluoroethylene (PTFE) graft patency. Twenty-five dogs had 4 mm x 7 cm PTFE grafts implanted bilaterally into the femoral arteries. A subcutaneous infusion pump was used to deliver either saline solution (control) or 9-beta-methyl carbacyclin (Ciprostine) at 100 (CARB-100) or 200 ng/kg/min (CARB-200) through a femoral artery branch just proximal to one of the femoral grafts, with the contralateral graft serving as a noninfused control. Graft-platelet deposition (with 111 In-labeled platelets) was measured between the fifth and seventh days, with patency determined on the seventh day. Dogs were classified as aggregators (AGG [+]) if the preoperative epinephrine-enhanced sodium arachidonate platelet aggregation was greater than 20%. CARB-200 infusion significantly improved ipsilateral graft patency (80%) compared with noninfused grafts (50%, p less than 0.05), or grafts in control and CARB-100 dogs (43%, p less than 0.05). Anastomotic platelet deposition was decreased bilaterally in CARB-200 dogs by 45% to 59% compared with CARB-100 and control dogs (p less than 0.05). With the exception of grafts infused with CARB-200, AGG (+) dogs had significantly lower graft patency (26%) than nonaggregator AGG (-) dogs (71%, p less than 0.01). CARB-200 infusion significantly improved graft patency in AGG (+) dogs (71%), compared with control and CARB-100-infused grafts (19%, p less than 0.025). Intra-arterial 9-beta-methyl carbacyclin improved early PTFE graft patency and inhibited platelet deposition in a severe canine model, independent of baseline platelet aggregation status, which also had an important effect on graft patency

  19. Rupture of Model 48Y UF6 cylinder and release of uranium hexafluoride, Sequoyah Fuels Facility, Gore, Oklahoma, January 4, 1986. Volume 1

    International Nuclear Information System (INIS)

    1986-02-01

    At 11:30 a.m. on January 4, 1986, a Model 48Y UF 6 cylinder filled with uranium hexafluoride (UF 6 ) ruptured while it was being heated in a steam chest at the Sequoyah Fuels Conversion Facility near Gore, Oklahoma. One worker died because he inhaled hydrogen fluoride fumes, a reaction product of UF 6 and airborne moisture. Several other workers were injured by the fumes, but none seriously. Much of the facility complex and some offsite areas to the south were contaminated with hydrogen fluoride and a second reaction product, uranyl fluoride. The interval of release was approximately 40 minutes. The cylinder, which had been overfilled, ruptured while it was being heated because of the expansion of UF 6 as it changed from the solid to the liquid phase. The maximum safe capacity for the cylinder is 27,560 pounds of product. Evidence indicates that it was filled with an amount exceeding this limit. 18 figs

  20. Travelling TexTs alla Nordic Digital Humanities Conference: Riflessioni sulla situazione di Digital Humanities nell’ottica della storia letteraria finlandese

    Directory of Open Access Journals (Sweden)

    Viola Parente-Čapková

    2016-12-01

    Full Text Available In my contribution, I intend to offer a report on the first conference of Nordic Digital Humanities held in Oslo on March 15-17 2016. I begin with a brief note on the present situation of the discipline, and, following the arguments brought up during the conference, reflect on its existence, development and problems. Then I concentrate on the presentation of the HERA funded Joint Research Project Travelling TexTs 1790–1914: Transnational Reception of Women’s Writing at the Fringes of Europe (Finland, Norway, Slovenia, Spain, The Netherlands and the importance of the digital tool for the project work. I tackle the concept of distant and close reading and comment briefly on the possibilities which such projects offer in terms of new ways of writing and teaching (Finnish literary history.

  1. Effect of gamma irradiation on the structural, mechanical and optical properties of polytetrafluoroethylene sheet

    Science.gov (United States)

    Mohammadian-Kohol, M.; Asgari, M.; Shakur, H. R.

    2018-04-01

    In this study, the effects of gamma radiation on the chemical structure, mechanical and optical properties of polytetrafluoroethylene (PTFE) sheet were investigated with various doses up to 12 kGy. The chemical changes in the structure were studied by FTIR spectroscopy. Also, effects of radiation on the different mechanical parameters such as Young's modulus, toughness, strain, and stress were studied at the maximum tolerable force and the fracture points. Furthermore, changing the various optical parameters such as absorption coefficient, Urbach energy, optical band gaps, refractive index, optical dispersion parameters and plasma resonance frequency were studied by UV-visible spectroscopy. Formation of a band at 1594 cm-1, which was belonged to double carbon bonds, indicated that chain-scission was occurred at 12 kGy gamma irradiation dose. As well, the mechanical results showed an increase in the elastic behavior of PTFE sheets and a decrease in the plastic behavior of it with absorbed dose increasing. Moreover, the results showed that gamma irradiation can effectively change the various optical properties of PTFE sheets due to different phenomena such as degradation of the main chains, occurring chain-scission, formation of free radicals and cross-linking in the polymer structure.

  2. The significant adhesion enhancement of Ag–polytetrafluoroethylene antibacterial coatings by using of molecular bridge

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Ruijie, E-mail: guoruijie@tyut.edu.cn [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan, 030024 (China); Yin, Guangda; Sha, Xiaojuan [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan, 030024 (China); Zhao, Qi [Division of Mechanical Engineering and Mechatronics, University of Dundee, Dundee, DD1 4HN (United Kingdom); Wei, Liqiao; Wang, Huifang [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan, 030024 (China)

    2015-06-30

    Highlights: • The more effective coupling agent is employed to modify surface. • S–Ag displays more intensive bond strength than that of N–Ag. • The coatings possess the highest level of adhesion. - Abstract: Weak adhesion between the metal-based antibacterial coatings and polymer substrates limits their clinical applications; surface modification is an effective way to solve this intrinsic problem. In this study, UV irradiation was employed to activate the inert silicon rubber substrates, and the grafting of coupling agent (3-mercaptopropyl) trimethoxy silane into the UV-irradiated substrates generated reactive surface containing −SH groups. During electroless plating S which has lone pair electrons anchored Ag{sup +} and produced antibacterial coatings with improved adhesion. The grafting of (3-mercaptopropyl) trimethoxy silane into silicon rubber was verified by X-ray photoelectron spectroscopy (XPS). The adhesion was tested by American Society of Testing Materials (ASTM D 3359-02). Surface elements content and distribution were observed and analyzed by X-ray energy disperse spectroscopy (EDS). The antibacterial performance was characterized by inhibition halo test and shake flash method. The results showed that the as-prepared composite Ag–polytetrafluoroethylene coatings possessed remarkably enhanced adhesion and superior antibacterial activity.

  3. Efeito leishmanicida in vitro do látex de Croton lechleri (Euphorbiaceae

    Directory of Open Access Journals (Sweden)

    Ana Paula Azevedo Santos

    2016-07-01

    Full Text Available A Leishmaniose Tegumentar Americana é uma infecção causada por uma variedade de espécies de Leishmania, é transmitida ao homem por flebotomíneos. Os antimoniais pentavalentes são utilizados na quimioterapia dessa doença; no entanto, esses fármacos provocam uma série de efeitos colaterais, além de apresentar altos índices de toxicidade. Na busca por novos agentes leishmanicidas, avaliamos in vitro o extrato do látex de Croton lechleri (Sangue de dragão frente a formas promastigotas de Leishmania amazonensis e Leishmania guyanensis. O extrato foi obtido através da desidratação do látex de C. lechleri e diluído em solução 10% de etanol em salina tamponada com fosfato. As promastigotas de Leishmania foram cultivadas juntamente com o extrato nas concentrações de 6,25; 12,5 e 25μg/ mL por 72 horas. O extrato apresentou eficácia em todas as concentrações testadas apresentando um IC 50 (concentração inibitória de 5,04μg/mL para L. amazonensis e IC 50 de 9,05μg/mL para L. guyanensis. Foi realizada a avaliação citotóxica em células J774 nas mesmas concentrações usadas no ensaio leishmanicida, porém a concentração de 25μg/mL apresentou  índice de toxicidade de aproximadamente 50% para a célula hospedeira. Os testes realizados mostraram-sepromissores, pois o extrato testado também foi capaz de inibir o crescimento de promastigotas de L. amazonensis após ensaio de infecção com células J774.Palavras-chave: Croton lechleri. Atividade leishmanicida. Atividade citotóxica. ABSTRACTIn vitro leishmanicidal effect of Croton lechleri latexCutaneous Leishmaniasis is an infection caused by a several species of Leishmania, is transmitted to humans by phlebotomine sandflies. Pentavalent antimonial compounds are used in the chemotherapy of this disease; however, these drugs cause several collateral effects, besides presenting high levels of toxicity. The search for new antiLeishmanial agents, we assessed in vitro the

  4. Evaluación de un método de aglutinación con látex para la detección de proteína C reactiva Agglutination evaluation method related to use of latex to detection of reactive C protein

    Directory of Open Access Journals (Sweden)

    Ana María Guerreiro Hernández

    2009-04-01

    Full Text Available Se evaluó un método de aglutinación con látex para la detección de proteína C reactiva (PCR (PCR-Látex, CENTIS empleándose como referencia un test turbidimétrico (PCR-Turbilátex, Spinreact. Se procesaron en paralelo 97 sueros de pacientes con clínica sugestiva de inflamación y sepsis. El análisis estadístico incluyó la determinación de la sensibilidad, especificidad, valor predictivo positivo (VPP, valor predictivo negativo (VPN y límites de detección. Los resultados obtenidos de sensibilidad: 97,8 %; especificidad: 98,0 %; VPP: 97,8 %; VPN: 98,0 %, con un límite de detección de 6 mg/L, pueden considerarse de satisfactorios, lo que permite contar con un procedimiento sencillo, rápido y eficiente que no requiere de un equipamiento especial.Agglutination evaluation method related to use of latex for detection of reactive C protein (RCP (RCP-Latex, CENTIS was evaluated, using as reference a turbidimetry test (RCP-Turbilatex, Spinreact. In parallel, 97 sera from patients with possibilities of inflammation and sepsis were processed. Statistical analysis included determination of sensitivity, specificity, positive predictive value (PPV, negative predictive value (NPV, and detection limits. Results achieved for sensitivity: 97,8 %; specificity: 98,0 %; NVP: 97,8 %; NPV: 98 % with a detection limit of 6 mg/L, may be considered of satisfactory, allowing to have a simple, fast, and efficient procedure without a especial equipment.

  5. Evaluación de un método de aglutinación con látex para la detección de factor reumatoide Evaluation of a latex agglutination method for the detection of rheumatoid factor

    Directory of Open Access Journals (Sweden)

    Ana M. Guerreiro Hernández

    2008-04-01

    Full Text Available Se evaluó un método de aglutinación con látex de producción nacional (Centis, para la detección de factor reumatoide, empleándose como procedimiento de referencia un ensayo turbidimétrico con látex (Spin React, España en un grupo de pacientes con artritis reumatoide. Los resultados obtenidos en el método evaluado: sensibilidad 93 %; especificidad 80 %; valor predictivo positivo 97,6 %; valor predictivo negativo 57,1 %; y un límite de detección de 15 UI/mL, indican su calidad y utilidad.An agglutination method with latex of national production (Centis was evaluated to detect the rheumatoid factor by using a turbidimetric assay with latex (Spin React, Spain as a reference procedure in a group of patients with rheumatoid arthritis. The results obtained in the evaluated method (sensitivity 93 %, specificity 80 %, positive predictive value 97.6 %, negative predictive value 57.1 %, and a detection limit of 15 UI/mL showed its quality and usefulness.

  6. Plasma treatment of expanded PTFE offers a way to a biofunctionalization of its surface

    International Nuclear Information System (INIS)

    Baquey, Ch.; Palumbo, F.; Porte-Durrieu, M.C.; Legeay, G.; Tressaud, A.; D'Agostino, R.

    1999-01-01

    Biointegration is the ideal outcome which is expected for an artificial implant. That means that the phenomena which seats at the interface between the implant and the host tissues does not induce neither any deleterious effect, such as chronic inflammatory response, nor the formation of unusual tissues. Thus it is of paramount importance to design biomaterials, used for the fabrication of implants, with the best appropriate surface properties. At the same time these biomaterials must feature bulk properties which meet other requirements, especially mechanical properties, deriving from the intended function of the implant in which they are involved. As it is quite impossible to design biomaterials which fulfil at the same time both types of requirements, it is commonly agreed that the solution to this issue goes through the selection or the design of biomaterials with adequate bulk properties, and a further treatment of the surface which would improve the properties of the latter. In this respect ionizing radiations and plasma based treatments, offer a wide panel of possibilities; as an example we describe here how the surface of expanded poly(tetrafluoroethylene) samples can be activated using cold plasma, in order to open a way to chemical modifications of such a surface. Subsequently, Radio Frequency Glow Discharge (RFGD) containing oligopeptides, known for their role in mediating the adhesion of cells to the extracellular matrix, were bound to the modified surface, and the affinity of endothelial cells for the latter was investigated

  7. Airborne nanoparticle concentrations in the manufacturing of polytetrafluoroethylene (PTFE) apparel.

    Science.gov (United States)

    Vosburgh, Donna J H; Boysen, Dane A; Oleson, Jacob J; Peters, Thomas M

    2011-03-01

    One form of waterproof, breathable apparel is manufactured from polytetrafluoroethylene (PTFE) membrane laminated fabric using a specific process to seal seams that have been sewn with traditional techniques. The sealing process involves applying waterproof tape to the seam by feeding the seam through two rollers while applying hot air (600 °C). This study addressed the potential for exposure to particulate matter from this sealing process by characterizing airborne particles in a facility that produces more than 1000 lightweight PTFE rain jackets per day. Aerosol concentrations throughout the facility were mapped, breathing zone concentrations were measured, and hoods used to ventilate the seam sealing operation were evaluated. The geometric mean (GM) particle number concentrations were substantially greater in the sewing and sealing areas (67,000 and 188,000 particles cm⁻³)) compared with that measured in the office area (12,100 particles cm⁻³). Respirable mass concentrations were negligible throughout the facility (GM = 0.002 mg m⁻³) in the sewing and sealing areas). The particles exiting the final discharge of the facility's ventilation system were dominated by nanoparticles (number median diameter = 25 nm; geometric standard deviation of 1.39). The breathing zone particle number concentrations of the workers who sealed the sewn seams were highly variable and significantly greater when sealing seams than when conducting other tasks (p < 0.0001). The sealing workers' breathing zone concentrations ranged from 147,000 particles cm⁻³ to 798,000 particles cm⁻³, and their seam responsibility significantly influenced their breathing zone concentrations (p = 0.03). The finding that particle number concentrations were approximately equal outside the hood and inside the local exhaust duct indicated poor effectiveness of the canopy hoods used to ventilate sealing operations.

  8. Inertial cavitation initiated by polytetrafluoroethylene nanoparticles under pulsed ultrasound stimulation.

    Science.gov (United States)

    Jin, Qiaofeng; Kang, Shih-Tsung; Chang, Yuan-Chih; Zheng, Hairong; Yeh, Chih-Kuang

    2016-09-01

    Nanoscale gas bubbles residing on a macroscale hydrophobic surface have a surprising long lifetime (on the order of days) and can serve as cavitation nuclei for initiating inertial cavitation (IC). Whether interfacial nanobubbles (NBs) reside on the infinite surface of a hydrophobic nanoparticle (NP) and could serve as cavitation nuclei is unknown, but this would be very meaningful for the development of sonosensitive NPs. To address this problem, we investigated the IC activity of polytetrafluoroethylene (PTFE) NPs, which are regarded as benchmark superhydrophobic NPs due to their low surface energy caused by the presence of fluorocarbon. Both a passive cavitation detection system and terephthalic dosimetry was applied to quantify the intensity of IC. The IC intensities of the suspension with PTFE NPs were 10.30 and 48.41 times stronger than those of deionized water for peak negative pressures of 2 and 5MPa, respectively. However, the IC activities were nearly completely inhibited when the suspension was degassed or ethanol was used to suspend PTFE NPs, and they were recovered when suspended in saturated water, which may indicates the presence of interfacial NBs on PTFE NPs surfaces. Importantly, these PTFE NPs could sustainably initiate IC for excitation by a sequence of at least 6000 pulses, whereas lipid microbubbles were completely depleted after the application of no more than 50 pulses under the same conditions. The terephthalic dosimetry has shown that much higher hydroxyl yields were achieved when PTFE NPs were present as cavitation nuclei when using ultrasound parameters that otherwise did not produce significant amounts of free radicals. These results show that superhydrophobic NPs may be an outstanding candidate for use in IC-related applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Embolization of the Systemic Arterial Supply via a Detachable Silicon Balloon in a Child with Scimitar Syndrome

    International Nuclear Information System (INIS)

    Sahin, Sinan; Celebi, Ahmet; Yalcin, Yalim; Saritas, Mustafa; Bilal, Mehmet S.; Celik, Levent

    2005-01-01

    Scimitar syndrome is a rare congenital disorder. It is characterized by partial or total abnormal venous drainage of the right lung into the inferior vena cava, which is often associated with anomalous systemic arterial supply to the right lung, congenital cardiac anomalies, hypoplasia of the right lung and bronchial anomalies. Symptoms depend on the degree of the shunt and severity of the associated anomalies, which determine the treatment. We present a 6-year-old boy who was diagnosed as having the adult form of scimitar syndrome during evaluation for recurrent pulmonary infections, and underwent embolization with a detachable silicon balloon of the anomalous systemic arterial supply from the abdominal aorta to the right lower lung lobe. Successful elective surgery was performed 6 months later, in which right pulmonary veins were directed to the left atrium using a Gore-Tex patch by creating an intra-atrial tunnel. The patient has been symptom-free period during 6 months of follow-up, which supports the idea that recurrent pulmonary infections can be eliminated by embolization of the anomalous arterial supply

  10. [TECHNIQUES IN MITRAL VALVE REPAIR VIA A MINIMALLY INVASIVE APPROACH].

    Science.gov (United States)

    Ito, Toshiaki

    2016-03-01

    In mitral valve repair via a minimally invasive approach, resection of the leaflet is technically demanding compared with that in the standard approach. For resection and suture repair of the posterior leaflet, premarking of incision lines is recommended for precise resection. As an alternative to resection and suture, the leaflet-folding technique is also recommended. For correction of prolapse of the anterior leaflet, neochordae placement with the loop technique is easy to perform. Premeasurement with transesophageal echocardiography or intraoperative measurement using a replica of artificial chordae is useful to determine the appropriate length of the loops. Fine-tuning of the length of neochordae is possible by adding a secondary fixation point on the leaflet if the loop is too long. If the loop is too short, a CV5 Gore-Tex suture can be passed through the loop and loosely tied several times to stack the knots, with subsequent fixation to the edge of the leaflet. Finally, skill in the mitral valve replacement technique is necessary as a back-up for surgeons who perform minimally invasive mitral valve repair.

  11. Core-Shell Al-Polytetrafluoroethylene (PTFE) Configurations to Enhance Reaction Kinetics and Energy Performance for Nanoenergetic Materials.

    Science.gov (United States)

    Wang, Jun; Qiao, Zhiqiang; Yang, Yuntao; Shen, Jinpeng; Long, Zhang; Li, Zhaoqian; Cui, Xudong; Yang, Guangcheng

    2016-01-04

    The energy performance of solid energetic materials (Al, Mg, etc.) is typically restricted by a natural passivation layer and the diffusion-limited kinetics between the oxidizer and the metal. In this work, we use polytetrafluoroethylene (PTFE) as the fluorine carrier and the shielding layer to construct a new type of nano-Al based fuels. The PTFE shell not only prevents nano-Al layers from oxidation, but also assists in enhancing the reaction kinetics, greatly improving the stability and reactivity of fuels. An in situ chemical vapor deposition combined with the electrical explosion of wires (EEW) method is used to fabricate core-shell nanostructures. Studies show that by controlling the stoichiometric ratio of the precursors, the morphology of the PTFE shell and the energy performance can be easily tuned. The resultant composites exhibit superior energy output characters than that of their physically mixed Al/PTFE counterparts. This synthetic strategy might provide a general approach to prepare other high-energy fuels (Mg, Si). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Sequential diffusion of ammonium and nitrate from soil extracts to a polytetrafluoroethylene trap for 15N determination

    DEFF Research Database (Denmark)

    Sørensen, P.; Jensen, E.S.

    1991-01-01

    A novel diffusion method was used for preparation of NH4+- and NO3--N samples from soil extracts for N-15 determination. Ammonium, and nitrate following reduction to ammonia, are allowed to diffuse to an acid-wetted glass filter enclosed in polytetrafluoroethylene tape. The method was evaluated...... with simulated soil extracts obtained using 50 ml of 2 M potassium chloride solution containing 130-mu-g of NH4+-N (2.3 atom% N-15) and 120-mu-g of NO3--N (natural N-15 abundance). No cross-over in the N-15 abundances of NH4+-N and NO3--N was observed, indicating a quantitative diffusion process (72 h, 25...

  13. Anticorrosion Coating of Carbon Nanotube/Polytetrafluoroethylene Composite Film on the Stainless Steel Bipolar Plate for Proton Exchange Membrane Fuel Cells

    Directory of Open Access Journals (Sweden)

    Yoshiyuki Show

    2013-01-01

    Full Text Available Composite film of carbon nanotube (CNT and polytetrafluoroethylene (PTFE was formed from dispersion fluids of CNT and PTFE. The composite film showed high electrical conductivity in the range of 0.1–13 S/cm and hydrophobic nature. This composite film was applied to stainless steel (SS bipolar plates of the proton exchange membrane fuel cell (PEMFC as anticorrosion film. This coating decreased the contact resistance between the surface of the bipolar plate and the membrane electrode assembly (MEA of the PEMFC. The output power of the fuel cell is increased by 1.6 times because the decrease in the contact resistance decreases the series resistance of the PEMFC. Moreover, the coating of this composite film protects the bipolar plate from the surface corrosion.

  14. Properties of carbon composite paper derived from coconut coir as a function of polytetrafluoroethylene content

    Science.gov (United States)

    Destyorini, Fredina; Indriyati; Indayaningsih, Nanik; Prihandoko, Bambang; Zulfia Syahrial, Anne

    2018-03-01

    The carbon composite papers were produced by utilizing carbon materials from coconut coir. In the present work, carbon composite papers (CCP) were prepared by mixing carbon materials in the form of powder and fibre with polymer (ethylene vinyl acetate and polyethylene glycol) in xylene at 100°C. Then, polytetrafluoroethylene (PTFE) with different content was used to treat the surface of CCP. The properties of PTFE-coated CCP were analysed by means of contact angle measurement, tensile testing, porosity, density, and electrical conductivity measurements. As expected, all CCP’s surfaces treated with PTFE were found to be hydrophobic with contact angle >120° and relatively constant during 60 minutes measurement. Furthermore, water contact angle, density, and mechanical properties of CCP generally increase with increasing PTFE content. However, the porosity and electrical conductivity of CCP decrease slightly as the PTFE content increased from 0 wt% to 30 wt%. Based on the observation and analysis, the optimum PTFE content on CCP was 20 %, in which the mechanical properties and hydrophobicity behaviour were improved significantly, but it was only caused a very small drop in porosity and electrical conductivity

  15. Expandable stents.

    Science.gov (United States)

    Nesbitt, J C; Carrasco, H

    1996-05-01

    Expandable metallic stents are effective in selected patients with malignant or benign airway stenoses. When used for malignant lesions, the primary purpose of the stent is to improve the quality of life; stents are usually chosen for palliation of symptoms in recognition of the low likelihood of success for other therapy. For patients with benign stenoses, the stents provide a permanent source of structural support to alleviate the narrowed segment. The advantages of the expandable metallic stents are as follows: (1) they can be inserted through an endotracheal tube or under local anesthesia with relative simplicity under fluoroscopic guidance; (2) they do not impair the drainage of sputum because ciliary movement is not interrupted; (3) over a period of a few weeks, the meshwork is gradually covered with mucosa as the stent becomes incorporated into the airway wall; (4) ventilation usually is not impaired if the metallic mesh stent covers another nonstenosed bronchus, because the interstices of the stent are nonobstructive; and (5) they are dynamic and continue to expand over time, particularly if concurrent treatment achieves an effect on the lesion that caused stenosis. Disadvantages of the expandable stent include (1) they often are only temporarily effective for tracheobronchial stenosis due to intraluminal tumor or granulation tissue, both of which can grow between the wires; (2) they are considered permanent stents because removal is difficult; and (3) they can be poorly positioned during placement or can become displaced by progressive migration after placement, and they cannot be repositioned. A relative contraindication to insertion is an inflammatory process or infection that can predispose to granulation formation, particularly at the points of maximal contact pressure of the stent to the airway mucosa. In the presence of inflammation, it may be better to use a silicone prosthesis until the inflammatory process subsides and fibrosis occurs. Granulation

  16. Structure and thermoelectric property of Te doped paracostibite CoSb1-xTexS compounds

    Science.gov (United States)

    You, Yonghui; Su, Xianli; Liu, Wei; Yan, Yonggao; Fu, Jiefei; Cheng, Xin; Zhang, Cheng; Tang, Xinfeng

    2018-06-01

    Paracostibite (CoSbS), a newly developed thermoelectric material, has aroused lots of interest due to its highly earth abundant and inexpensive constituent elements and potential application for thermoelectric power generation in the intermediate temperature range. Herein, a series of CoSb1-xTexS (x = 0-0.09) compounds were prepared by vacuum melting and annealing followed by SPS processing, and the effects of Te doping on the structure and thermoelectric properties were systematically investigated. Doping Te on the Sb site increases the carrier concentration up to 7.24 × 1020 cm-3 for CoSb0.93Te0.07S compound which is several orders of magnitude higher than that of un-doped CoSbS, and enhances the power factor. The maximum power factor of 14.07 μW cm-1 K-2 is attained at 900 K. Concomitantly, doping with Te on the Sb site leads to effective scattering of heat carrying phonon, accompanying with a strong suppression of the thermal conductivity with the increase of Te content, resulting in an increase of the ZT. A maximum ZT of 0.43 at 900 K is attained for CoSb0.93Te0.07S compound, which is 139% higher than that of un-doped CoSbS compound.

  17. AMERİKA BİRLEŞİK DEVLETLERİ’NDE DEVLETİN YENİDEN YAPILANDIRILMASINA YÖNELİK UYGULAMALAR (Clinton-Al Gore Girişimi: 1993-2001)

    OpenAIRE

    Aktan, Coşkun Can

    2018-01-01

    ABD’nde devletin yeniden yapılandırılması çalışmaları William Clinton’un başkanlığı döneminde Başkan Yardımcılığı görevini yürüten Al Gore öncülüğünde yürütülmüştür. ABD’nde bu amaçla National Performance Review adlı bir de yeniden yapılandırma laboratuvarı kurulmuştur. Bu kurum daha sonra National Partnership for Reinventing Government adını almıştır. Bu çalışmada 1993-2001 yılları arasında ABD’nde devletin yeniden yapılandırılmasına yönelik uygulamalar incelenmektedir....

  18. What Expands in an Expanding Universe?

    Science.gov (United States)

    Pacheco, José A De Freitas

    2015-01-01

    In the present investigation, the possible effects of the expansion of the Universe on systems bonded either by gravitational or electromagnetic forces, are reconsidered. It will be shown that the acceleration (positive or negative) of the expanding background, is the determinant factor affecting planetary orbits and atomic sizes. In the presently accepted cosmology (ΛCDM) all bonded systems are expanding at a decreasing rate that tends to be zero as the universe enters in a de Sitter phase. It is worth mentioning that the estimated expansion rates are rather small and they can be neglected for all practical purposes.

  19. What Expands in an Expanding Universe?

    Directory of Open Access Journals (Sweden)

    JOSÉ A. DE FREITAS PACHECO

    2015-12-01

    Full Text Available ABSTRACT In the present investigation, the possible effects of the expansion of the Universe on systems bonded either by gravitational or electromagnetic forces, are reconsidered. It will be shown that the acceleration (positive or negative of the expanding background, is the determinant factor affecting planetary orbits and atomic sizes. In the presently accepted cosmology (ΛCDM all bonded systems are expanding at a decreasing rate that tends to be zero as the universe enters in a de Sitter phase. It is worth mentioning that the estimated expansion rates are rather small and they can be neglected for all practical purposes.

  20. Budget impact analysis of heparin-bonded polytetrafluoroethylene grafts (Propaten) against standard polytetrafluoroethylene grafts for below-the-knee bypass in patients with critical limb ischaemia in France

    Science.gov (United States)

    Vergnaud, Simon; Riche, Valéry-Pierre; Tessier, Philippe; Mauduit, Nicolas; Kaladji, Adrien; Gouëffic, Yann

    2018-01-01

    Objectives To evaluate the budget impact of progressive replacement of standard polytetrafluoroethylene (PTFE) grafts by heparin-bound PTFE (Propaten) for below-the-knee (BTK) bypass in patients with critical limb ischaemia (CLI). Design From a review of the scientific literature, we calculated a theoretical BTK primary patency for Propaten grafts. Using the French hospital expenditure database (PMSI), we retrospectively estimated a rehospitalisation rate for standard PTFE grafts. From these data, a model was created to assess the budget impact of a progressive replacement from standard PTFE grafts to Propaten grafts over a 5-year horizon. We performed an univariate sensitivity analysis to assess the robustness of our results. Setting French National Health Insurance (FNHI) perspective. Participant Patients with CLI. Main outcome measures Budget impact analysis. Results Data extraction from the PMSI revealed that 656 patients were treated with PTFE grafts in 2011 in French public hospitals for a BTK bypass. Assuming a 2-year survival rate of 76.8%, observed reinterventions rate for standard PTFE grafts at 24 months from the PMSI was 35.1%. The mean rehospitalisation cost was €10 689. The budget impact analysis based on these data found a net cumulative 5-year payer budget reduction of €112 420 in favour of Propaten, under the assumption of a 75.6% primary patency for Propaten grafts for a projected population of 3215 patients of which 801 received a Propaten graft. Conclusions Our budget impact analysis showed a positive impact on the national health insurance budget of the replacement of standard PTFE grafts by Propaten grafts for BTK bypass in patients with CLI in France. This supports the enactment of a reimbursement policy by the FNHI. PMID:29490953

  1. Herida por asta de toro en el área maxilofacial: revisión de la literatura y presentación de un caso Maxillofacial injury by bull goring: literature review and case report

    Directory of Open Access Journals (Sweden)

    J.L. Crespo Escudero

    2008-10-01

    ías traumáticas de la región craneofacial y cuyas características deben ser conocidas. Aunque son lesiones graves por el peligro de obstrucción de la vía aérea o de shock hemorrágico, su pronóstico es favorable. El éxito en el manejo y tratamiento de los pacientes con este tipo de heridas se fundamenta en una rápida identificación de las lesiones, con el fin de realizar una terapéutica quirúrgica correcta en el menor tiempo posible desde que se produce el accidente.Introduction. Injuries produced by bull goring are relatively common in Spain and South American countries, where bullfights are scheduled regularly. These wounds have specific characteristics that differentiate them from any other type of wounds. Material and methods. In the summer of 2005, an 18-year-old male patient was brought to the Hospital 12 de Octubre by emergency services after being gored in the cervicofacial region during the running of the bulls in San Sebastián de los Reyes. The patient had an anfractuous, penetrating and blunt wound extending from the left supraclavicular region to the left lip commissure, comminuted fracture of the left mandibular angle and right mandibular body, dentoalveolar fractures of pieces 1.3 to 2.3, and severe laceration of the lingual musculature and mouth floor. Discussion. Most patients who suffer multiple injuries as a result of bull goring are men, with a mean age of 30 years. Victims usually are spontaneous participants, bullfighting fans rather than professional bullfighters. The wounds produced by the horns of the bull may be located anywhere in the body, but the most frequent location in all the series reviewed was the lower limb. The cervicofacial region is one of less frequently affected regions in all the series. All authors agree that these injuries have a low incidence despite the huge number of bullfight fans and curious spectators who are attracted by bullfight events. Emergency treatment is required because of the particular characteristics

  2. Raman Spectroscopy of Two-Dimensional Bi2TexSe3 − x Platelets Produced by Solvothermal Method

    Directory of Open Access Journals (Sweden)

    Jian Yuan

    2015-08-01

    Full Text Available In this paper, we report a facile solvothermal method to produce both binary and ternary compounds of bismuth chalcogenides in the form of Bi2TexSe3 − x. The crystal morphology in terms of geometry and thickness as well as the stoichiometric ratio can be well controlled, which offers the opportunities to systematically investigate the relationship between microstructure and phonon scattering by Raman spectroscopy. Raman spectra of four compounds, i.e., Bi2Se3, Bi2Se2Te, Bi2SeTe2 and Bi2Te3, were collected at four different excitation photon energies (2.54, 2.41, 1.96, and 1.58 eV. It is found that the vibrational modes are shifted to higher frequency with more Se incorporation towards the replacement of Te. The dependence of Raman vibrational modes on excitation photon energy was investigated. As the excitation photon energy increases, three Raman vibrational modes (A1g1, Eg2 and A1g2 of the as-produced compounds move to low frequency. Three Infrared-active (IR-active modes were observed in thin topological insulators (TIs crystals.

  3. Self-lubricating layer consist of polytetrafluoroethylene micropowders and fluorocarbon acrylate resin formation on surface of geotextile

    Science.gov (United States)

    Long, Xiaoyun; He, Lifen; Zhang, Yan; Ge, Mingqiao

    2018-04-01

    In this study, the self-lubricating layer consist of polytetrafluoroethylene (PTFE) micropowders and two types fluorocarbon acrylate resin were formed on the surface of geotextile, to improves the evenness and decreases the frictional angle value of geotextile surface. The surface and cross section morphology of geotextile were examined by scanning electron microscopy (SEM). It was determined that composite resin emulsion was evenly coated on the surface of geotextile, to form a even and complete self-lubricating layer, and it was strongly combined with the geotextile due to formation of the transition layer. The tensile fracture stress and strain values of samples were evaluated by mechanical properties measurement, the tensile fracture stress of the untreated and treated sample was approximately 5329 kN/m and 5452 kN/m while the elongation at the yield of them was approximately 85% to 83.9%, respectively. In addition, the frictional angle values of municipal solid waste (MSW)/geotextile interface was measured by the tilt table test, the values of untreated sample was 28.1° and 24.2° under the dry and moist condition, the values of treated sample was 16.2° and 9.8°, respectively.

  4. Induction of surface modification of polytetrafluoroethylene with proton ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Noh, I S; Kim, H R; Choi, Y J; Park, H S [Seoul National Univ. of Technology, Seoul (Korea, Republic of)

    2007-04-15

    Cardiovascular disease is one of the leading causes of the death in the USA and developed countries. More than 570,000 artery bypass graft surgeries per USA are performed each year, though percutaneous devices have abounded in extreme cases. Based on the surgery follow-ups, large diameter expanded polytetrafluoroethylene (ePTFE) (>5 mm) are clinically employed with good results but its clinical applications in smaller vessels is still problematic due to thrombosis and neointima formation. Achievement of high patency grafts has been to some extent achieved by numerous methods of surface modification techniques, but its results are less than its initial hopes. As examples, endothelial cells coated on the luminal surface of ePTFE has demonstrated limited success after recirculation. Surface modifications of PTFE film with either argon ion beam or UV light from Xe-excimer lamp were reported to increase its interaction with vascular endothelial cell. Surface modification of poly(lactide-co-glycolide)[PLGA] is also very important in tissue engineering, in where induction of its initial high cellular adhesion and spreading is a critical step for development of tissue engineering medical products. We previously reported tissue engineering of the hybrid ePTFE scaffold by seeding smooth muscle cells and subsequently evaluation of its tissue regeneration behaviors and stabilities with circulation of pulsatile flow. To improve its tissue engineering more quickly, we here performed surface modification of ePTFE and porous PLGA scaffold and evaluated its subsequent chemical and biological properties after treating its surface with low energy ion beams. The porous ePTFE was prepared in a round shape (diameter = 1 cm) and dried after organic solvent extraction for ion beam treatment. Another porous PLGA layers (d = 1 cm, t = 1 cm with approximately 92% porosity) were fabricated and treated its surface by irradiating low energy either nitrogen or argon ion beams (1 keV, 1x1015 ions

  5. Induction of surface modification of polytetrafluoroethylene with proton ion beams

    International Nuclear Information System (INIS)

    Noh, I. S.; Kim, H. R.; Choi, Y. J.; Park, H. S.

    2007-04-01

    Cardiovascular disease is one of the leading causes of the death in the USA and developed countries. More than 570,000 artery bypass graft surgeries per USA are performed each year, though percutaneous devices have abounded in extreme cases. Based on the surgery follow-ups, large diameter expanded polytetrafluoroethylene (ePTFE) (>5 mm) are clinically employed with good results but its clinical applications in smaller vessels is still problematic due to thrombosis and neointima formation. Achievement of high patency grafts has been to some extent achieved by numerous methods of surface modification techniques, but its results are less than its initial hopes. As examples, endothelial cells coated on the luminal surface of ePTFE has demonstrated limited success after recirculation. Surface modifications of PTFE film with either argon ion beam or UV light from Xe-excimer lamp were reported to increase its interaction with vascular endothelial cell. Surface modification of poly(lactide-co-glycolide)[PLGA] is also very important in tissue engineering, in where induction of its initial high cellular adhesion and spreading is a critical step for development of tissue engineering medical products. We previously reported tissue engineering of the hybrid ePTFE scaffold by seeding smooth muscle cells and subsequently evaluation of its tissue regeneration behaviors and stabilities with circulation of pulsatile flow. To improve its tissue engineering more quickly, we here performed surface modification of ePTFE and porous PLGA scaffold and evaluated its subsequent chemical and biological properties after treating its surface with low energy ion beams. The porous ePTFE was prepared in a round shape (diameter = 1 cm) and dried after organic solvent extraction for ion beam treatment. Another porous PLGA layers (d = 1 cm, t = 1 cm with approximately 92% porosity) were fabricated and treated its surface by irradiating low energy either nitrogen or argon ion beams (1 keV, 1x1015 ions

  6. Effect of flow on vascular endothelial cells grown in tissue culture on polytetrafluoroethylene grafts

    International Nuclear Information System (INIS)

    Sentissi, J.M.; Ramberg, K.; O'Donnell, T.F. Jr.; Connolly, R.J.; Callow, A.D.

    1986-01-01

    Vascular grafts lined with endothelial cells (EC) grown to confluence in culture before implantation may provide a thromboresistant flow surface. Growth of EC on and their adherence to currently available prosthetic materials under conditions of flow are two impediments remaining in the development of such a graft. To address these problems, 22 polytetrafluoroethylene grafts (PTFE) (5 cm by 4 mm inside diameter) were pretreated with collagen and fibronectin, seeded with 2 to 3 X 10(6) bovine aortic EC per graft, and placed in tissue culture (seeded grafts). Twenty-two grafts pretreated with collagen and fibronectin alone served as controls. After 2 weeks morphologic studies revealed that 20/22 seeded grafts were lined with a confluent endothelial layer. Indium 111-oxine was then used to label the EC-seeded grafts. After exposure to either low (25 ml/min) or high (200 ml/min) flow rates for 60 minutes in an in vitro circuit, examination of the luminal surface of the graft by light microscopy and scanning electron microscopy revealed minimal loss of EC. These findings were corroborated by radionuclide scans that showed an insignificant loss of the EC-associated indium label during exposure to flow (7% low flow, 11% high flow). Pretreatment of PTFE grafts with collagen and fibronectin thus promotes both attachment and adherence of EC even under flow conditions

  7. Wear Process Analysis of the Polytetrafluoroethylene/Kevlar Twill Fabric Based on the Components’ Distribution Characteristics

    Directory of Open Access Journals (Sweden)

    Gu Dapeng

    2017-12-01

    Full Text Available Polytetrafluoroethylene (PTFE/Kevlar fabric or fabric composites with excellent tribological properties have been considered as important materials used in bearings and bushing, for years. The components’ (PTFE, Kevlar, and the gap between PTFE and Kevlar distribution of the PTFE/Kevlar fabric is uneven due to the textile structure controlling the wear process and behavior. The components’ area ratio on the worn surface varying with the wear depth was analyzed not only by the wear experiment, but also by the theoretical calculations with our previous wear geometry model. The wear process and behavior of the PTFE/Kevlar twill fabric were investigated under dry sliding conditions against AISI 1045 steel by using a ring-on-plate tribometer. The morphologies of the worn surface were observed by the confocal laser scanning microscopy (CLSM. The wear process of the PTFE/Kevlar twill fabric was divided into five layers according to the distribution characteristics of Kevlar. It showed that the friction coefficients and wear rates changed with the wear depth, the order of the antiwear performance of the previous three layers was Layer III>Layer II>Layer I due to the area ratio variation of PTFE and Kevlar with the wear depth.

  8. Expanding subjectivities

    DEFF Research Database (Denmark)

    Lundgaard Andersen, Linda; Soldz, Stephen

    2012-01-01

    A major theme in recent psychoanalytic thinking concerns the use of therapist subjectivity, especially “countertransference,” in understanding patients. This thinking converges with and expands developments in qualitative research regarding the use of researcher subjectivity as a tool......-Saxon and continental traditions, this special issue provides examples of the use of researcher subjectivity, informed by psychoanalytic thinking, in expanding research understanding....

  9. Orthodontic space closure in combination with membrane supported healing of extraction sockets (MHE) a pilot study.

    Science.gov (United States)

    Tiefengraber, Julia; Diedrich, Peter; Fritz, Ulrike; Lantos, Peter

    2002-09-01

    In periodontology and implantology the guided bone regeneration (GBR) technique represents a well established and successful method for augmentation of alveolar bone. The aim of the present study was to evaluate what advantages, if any, are offered for orthodontic space closure by membrane supported healing of extraction sockets (MHE) (criteria: rate of movement, incidence of gingival clefts, atrophy of the alveolar bone). Within the scope of orthodontic therapy with a complete fixed appliance, three girls aged 11-14 years with indication for extraction of the first premolars were unilaterally augmented with an e-PTFE membrane (Gore-Tex((R)), W. L. Gore & Associates, Flagstaff, AZ, USA) immediately after premolar extraction. The study was performed in the split-mouth technique. An atraumatic extraction without digital compression was performed on the control side. The membranes were fixed with a Frios((R)) fixation set (Friadent, GmbH, Mannheim, Germany) and removed after 6 to 8 weeks. 1 week after membrane removal, space closure was started simultaneously with passive rectangular segmented archwires using Sentalloy((R)) closed coil springs (GAC International, Inc., Gräfelfing, Germany) at a constant force of 200 cN. The transversal and vertical dimensions of the alveolar bone the rate of space closure were determined clinically and radiographically. Complications were not observed in any patient. The MHE-treated alveolar region showed pronounced stability of the transversal dimension. Space closure was performed in all cases without gingival clefts being induced. The control side showed distinct atrophy as well as gingival clefts. No differences were recorded in the rate of space closure. The MHE technique seems to be a suitable means of creating favorable periodontal conditions for tooth movement, especially in cases of alveolar bone loss after extraction or trauma.

  10. Determinación de las características anatómicas de las arterias coronarias de cerdo mediante técnica de inyección con látex

    Directory of Open Access Journals (Sweden)

    Guillermo Rivera

    2015-06-01

    Full Text Available Objetivo: Determinar las características anatómicas de las arterias coronarias del cerdo, mediante inyección con látex. Materiales y métodos: Se usaron 100 corazones de cerdo. Se insertaron sondas Nelaton a través de las arterias coronarias y se les inyectó solución de látex y tinta china. Se determinó el diámetro y el punto de origen para la coronaria derecha, coronaria izquierda, interventricular paraconal y circunfleja. Se cuantificaron el número de ramas diagonales, marginales ventriculares izquierdas y postero laterales. Se determinó frecuencia de ramus intermedius y tipo de dominancia. Se realizó análisis estadístico con un error estándar del 5%, con el Epidat 3,1. Resultados: El 100% de los orígenes anatómicos de las arterias coronarias fueron normales. La dominancia mas frecuente fue la derecha, 73%. El promedio de número de ramas marginales izquierdas, diagonales y posterolaterales fue de 3. La frecuencia de ramus intermedius fue de 12%. El calculo de chi cuadrado de Pearson mostró significancia entre el ramus intermedius y número de ramas marginales izquierdas (p=0,0009. Conclusiones: Las características anatómicas de las arterias coronarias del cerdo son similares a las del humano. El ramus intermedius se comporta como una primera rama marginal izquierda y no como una primera rama diagonal como lo afirman algunos autores.

  11. Investigation on surface structure of potassium permanganate/nitric acid treated poly(tetrafluoroethylene)

    International Nuclear Information System (INIS)

    Fu, Congli; Liu, Shuling; Gong, Tianlong; Gu, Aiqun; Yu, Zili

    2014-01-01

    Highlights: • A new transformation (conversion) mechanism of PTFE surface from a hydrophobicity to a hydrophilicity was proposed through the treatment of KMnO 4 /HNO 3 . • Chemical reactions or defluorination of PTFE described in the reported paper was testified to be a misconceived conclusion by the combination of several testing measurements (IR, XPS, XRD and so on) in our present work. • Deposition of manganese oxide and/or manganese hydroxide on PTFE surface contributed to the hydrophilic property of the modified PTFE with KMnO 4 /HNO 3 treated. • The deposition thickness on the modified PTFE surface was about 5 μm, which was significantly helpful in enhancing the adhesive strength of PTFE with other materials. - Abstract: In the previous articles concerning the treatment of poly(tetrafluoroethylene) (PTFE) with potassium permanganate/nitric acid mixture, the conversion of a hydrophobic to a hydrophilic surface was partially assigned to the defluorination of PTFE and then the introduction of carbonyl and hydroxyl groups into the defluorinated sites. In the present work, PTFE sheets were treated with potassium permanganate/nitric acid, and the surfaces before and after treatment were comparatively characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The surface sediments of the treated PTFE were also determined by atomic absorption spectroscopy (AAS). The results indicate that the conversion of the hydrophobicity to the hydrophilicity on the modified PTFE surface is mainly due to the deposition of hydrophilic manganese oxides which covered the fluorocarbon surface, and no detectable chemical reactions of PTFE occur in the treating process

  12. Investigation on surface structure of potassium permanganate/nitric acid treated poly(tetrafluoroethylene)

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Congli; Liu, Shuling; Gong, Tianlong; Gu, Aiqun; Yu, Zili, E-mail: ziliyu@scu.edu.cn

    2014-10-30

    Highlights: • A new transformation (conversion) mechanism of PTFE surface from a hydrophobicity to a hydrophilicity was proposed through the treatment of KMnO{sub 4}/HNO{sub 3}. • Chemical reactions or defluorination of PTFE described in the reported paper was testified to be a misconceived conclusion by the combination of several testing measurements (IR, XPS, XRD and so on) in our present work. • Deposition of manganese oxide and/or manganese hydroxide on PTFE surface contributed to the hydrophilic property of the modified PTFE with KMnO{sub 4}/HNO{sub 3} treated. • The deposition thickness on the modified PTFE surface was about 5 μm, which was significantly helpful in enhancing the adhesive strength of PTFE with other materials. - Abstract: In the previous articles concerning the treatment of poly(tetrafluoroethylene) (PTFE) with potassium permanganate/nitric acid mixture, the conversion of a hydrophobic to a hydrophilic surface was partially assigned to the defluorination of PTFE and then the introduction of carbonyl and hydroxyl groups into the defluorinated sites. In the present work, PTFE sheets were treated with potassium permanganate/nitric acid, and the surfaces before and after treatment were comparatively characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The surface sediments of the treated PTFE were also determined by atomic absorption spectroscopy (AAS). The results indicate that the conversion of the hydrophobicity to the hydrophilicity on the modified PTFE surface is mainly due to the deposition of hydrophilic manganese oxides which covered the fluorocarbon surface, and no detectable chemical reactions of PTFE occur in the treating process.

  13. Expanding Thurston maps

    CERN Document Server

    Bonk, Mario

    2017-01-01

    This monograph is devoted to the study of the dynamics of expanding Thurston maps under iteration. A Thurston map is a branched covering map on a two-dimensional topological sphere such that each critical point of the map has a finite orbit under iteration. It is called expanding if, roughly speaking, preimages of a fine open cover of the underlying sphere under iterates of the map become finer and finer as the order of the iterate increases. Every expanding Thurston map gives rise to a fractal space, called its visual sphere. Many dynamical properties of the map are encoded in the geometry of this visual sphere. For example, an expanding Thurston map is topologically conjugate to a rational map if and only if its visual sphere is quasisymmetrically equivalent to the Riemann sphere. This relation between dynamics and fractal geometry is the main focus for the investigations in this work.

  14. Stability of nonfouling electroless nickel-polytetrafluoroethylene coatings after exposure to commercial dairy equipment sanitizers.

    Science.gov (United States)

    Huang, Kang; Goddard, Julie M

    2015-09-01

    Application of nonfouling coatings on thermal processing equipment can improve operational efficiency. However, to enable effective commercial translation, a need exists for more comprehensive studies on the stability of nonfouling coatings after exposure to different sanitizers. In the current study, the influence of different commercial dairy equipment sanitizers on the nonfouling properties of stainless steel modified with electroless Ni-polytetrafluoroethylene (PTFE) coatings was determined. Surface properties, such as dynamic contact angle, surface energy, surface morphology, and elemental composition, were measured before and after the coupons were exposed to the sanitizers for 168 cleaning cycles. The fouling behavior of Ni-PTFE-modified stainless steel coupons after exposure was also evaluated by processing raw milk on a self-fabricated benchtop-scale plate heat exchanger. The results indicated that peroxide sanitizer had only minor effect on the Ni-PTFE-modified stainless steel surface, whereas chlorine- and iodine-based sanitizers influenced the surface properties drastically. The coupons after 168 cycles of exposure to peroxide sanitizer accumulated the least amount of fouling material (4.44±0.24mg/cm(2)) compared with the coupons exposed to the other 3 sanitizers. These observations indicated that the Ni-PTFE nonfouling coating retained antifouling properties after 168 cycles of exposure to peroxide-based sanitizer, supporting their potential application as nonfouling coatings for stainless steel dairy processing equipment. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  15. Development of high performance lubricant through the compatibilization of polyalphaolefin, polyurea and irradiated polytetrafluoroethylene

    International Nuclear Information System (INIS)

    Ratao, Natalia T.; Zen, Heloisa A.; Lugao, Ademar B.

    2013-01-01

    High performance lubricants are essential for shipping and oil exploration industries for working under severe conditions of temperature, pressure and contamination. Polytetrafluoroethylene (PTFE) is widely used as a lubricating additive in greases for presenting the lowest known coefficient of friction, is commercially found irradiated in air, by this way can be grinded and oxygenated terminal groups can be formed. PTFE processed by ionizing radiation with 4μ average particle size was supplied by Uniflon and compared with the ultraviolet-irradiated PTFE with the same average particle size, from Dupont. The characterization of functional proprieties by drop point, oil separation and four ball test was conducted with a polyurea base grease additive with both types of PTFE. The chemical characterization was done with Differential Scanning Calorimetry (DSC). The drop point and oil separation tests showed that the Uniflon irradiated PTFE improved the thermal resistance and stability of polyurea grease due to the greater presence of the end groups increase the compatibility of the additive with the fluid. Four ball tests showed that the grease with Uniflon irradiated PTFE also has a better antiwear and extreme pressure performance because of the greater polarity of the molecules improving the dispersion and anchoring of the PTFE in metal surface voids, reducing wear. The PTFE processed by ionizing radiation showed greater compatibility with polyurea grease and polyalphaolefin fluid and the grease functional characteristics met the requirements for a high performance lubricant. (author)

  16. Five-year outcomes following a randomized trial of femorofemoral and femoropopliteal bypass grafting with heparin-bonded or standard polytetrafluoroethylene grafts

    DEFF Research Database (Denmark)

    Lindholt, Jes S.; Houlind, K.; Gottschalksen, B

    2016-01-01

    BACKGROUND: Cohort studies suggest superior long-term patency of luminal heparin-bonded polytetrafluoroethylene (Hb-PTFE) bypass grafts compared with standard PTFE grafts. The aim of this study was to compare the outcomes of Hb-PTFE grafts with those of standard PTFE grafts 5 years after...... a randomized trial. METHODS: Patients with intermittent claudication or critical limb ischaemia requiring femorofemoral or femoropopliteal bypass grafting were randomized in a clinical trial of Hb-PTFE versus standard PTFE in 11 Scandinavian centres between 2005 and 2009. Patients were followed up for 5 years...... of the primary outcome. Use of Hb-PTFE significantly improved patency by 37 per cent at 2 years, but 5 years after randomization there was no difference in primary patency (adjusted hazard ratio (HR) 0·95, 95 per cent c.i. 0·71 to 1·28; P = 0·748). In patients with critical limb ischaemia the use of Hb-PTFE...

  17. Ag-polytetrafluoroethylene composite coating on stainless steel as bipolar plate of proton exchange membrane fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Yu. [Laboratory of Fuel Cells, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road, Dalian 116023 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Hou, Ming; Shao, Zhigang; Yi, Baolian [Laboratory of Fuel Cells, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road, Dalian 116023 (China); Xu, Hongfeng; Hou, Zhongjun; Ming, Pingwen [Sunrise Power Co., Ltd., Dalian 116025 (China)

    2008-08-01

    Forming a coating on metals by surface treatment is a good way to get high performance bipolar plate of proton exchange membrane fuel cell (PEMFC). In our research, Ag-polytetrafluoroethylene (PTFE) composite film was electrodeposited with silver-gilt solution of nicotinic acid by a bi-pulse electroplating power supply on 316 L stainless steel bipolar plate of PEMFC. Surface topography, contact angle, interfacial conductivity and corrosion resistance of the bipolar plate samples were investigated. Results showed that the defects on the Ag-PTFE composite coating are greatly reduced compared with those on the pure Ag coating fabricated under the same condition; and the contact angle of the Ag-PTFE composite coating with water is 114 , which is much bigger than that of the pure Ag coating (73 ). In addition, the interfacial contact resistance of the composite coating stays as low as the pure Ag coating; and the bipolar plate sample with composite coating shows a close corrosion resistance to the pure Ag coating sample in potentiodynamic and potentiostatic tests. Coated 316 L stainless steel plate with Ag-PTFE composite coating exhibits well hydrophobic characteristic, less defects, high interfacial conductivity and good corrosion resistance, which shows a great potential of the application in PEMFC. (author)

  18. Fabrication of TiO_2-modified polytetrafluoroethylene ultrafiltration membranes via plasma-enhanced surface graft pretreatment

    International Nuclear Information System (INIS)

    Qian, Yingjia; Chi, Lina; Zhou, Weili; Yu, Zhenjiang; Zhang, Zhongzhi; Zhang, Zhenjia; Jiang, Zheng

    2016-01-01

    Graphical abstract: - Highlights: • Multifunctional TiO_2/PAA/PTFE ultrafiltration membrane was fabricated via tight coating of TiO_2 functional layer onto the plasma-assisted graft of PAA on PTFE. • The high water flux rate, remarkable enhanced ultrafiltration performance and excellent self-cleaning ability were demonstrated. • The formation of COO−Ti bidentate coordination between TiO_2 and PAA was responsible for the successful coating. - Abstract: Surface hydrophilic modification of polymer ultrafiltration membrane using metal oxide represents an effective yet highly challenging solution to improve water flux and antifouling performance. Via plasma-enhanced graft of poly acryl acid (PAA) prior to coating TiO_2, we successfully fixed TiO_2 functional thin layer on super hydrophobic polytetrafluoroethylene (PTFE) ultrafiltration (UF) membranes. The characterization results evidenced TiO_2 attached on the PTFE-based UF membranes through the chelating bidentate coordination between surface-grafted carboxyl group and Ti"4"+. The TiO_2 surface modification may greatly reduce the water contact angle from 115.8° of the PTFE membrane to 35.0° without degradation in 30-day continuous filtration operations. The novel TiO_2/PAA/PTFE membranes also exhibited excellent antifouling and self-cleaning performance due to the intrinsic hydrophilicity and photocatalysis properties of TiO_2, which was further confirmed by the photo-degradation of MB under Xe lamp irradiation.

  19. The Effect of Temperature on the Free Volume in Polytetrafluoroethylene Studied by Positron Annihilation Spectroscopy

    International Nuclear Information System (INIS)

    Abdel-Latif, R.M.; Mohamed, H.F.M.; Abdel-Hady, E.E.; Mohamed, S.S.

    2005-01-01

    The positron annihilation techniques have been applied to investigate the free volume holes in pure and doped polytetrafluoroethylene (PTFE) with glass as a function of temperature. The measurements were performed from room temperature up to 250 degree C. The lifetime spectra were analyzed using two methods; 1) Finite-term analysis to determine the average values of the orthopositronium (o-Ps) lifetime and its intensity using PATFIT program, 2) Continuous lifetime analysis to obtain the o-Ps lifetime and o-Ps hole volume distributions using MELT program. The ortho-positronium (o-Ps) lifetimes, (T3 and T4) are found to be vary depending upon the phase of the polymer. Within the temperature range two transitions can be observed. The first one is related to the glass transition temperature, T g (at 130 degree C for pure PTFE and at 110 degree C for doped PTFE with glass). The second one is the crystalline temperature at 210 degree C for the two samples. It was found that, T g is shifted toward the lower values (110 degree C) for doped PTFE with glass, which could be attributed to the increase in the degree of crystallinity. This is in consistent with the wide-angle x-ray scattering data. A correlation between the positron annihilation parameters and the electrical conductivity was achieved

  20. Performance assessment of retrospective meteorological inputs for use in air quality modeling during TexAQS 2006

    Science.gov (United States)

    Ngan, Fong; Byun, Daewon; Kim, Hyuncheol; Lee, Daegyun; Rappenglück, Bernhard; Pour-Biazar, Arastoo

    2012-07-01

    To achieve more accurate meteorological inputs than was used in the daily forecast for studying the TexAQS 2006 air quality, retrospective simulations were conducted using objective analysis and 3D/surface analysis nudging with surface and upper observations. Model ozone using the assimilated meteorological fields with improved wind fields shows better agreement with the observation compared to the forecasting results. In the post-frontal conditions, important factors for ozone modeling in terms of wind patterns are the weak easterlies in the morning for bringing in industrial emissions to the city and the subsequent clockwise turning of the wind direction induced by the Coriolis force superimposing the sea breeze, which keeps pollutants in the urban area. Objective analysis and nudging employed in the retrospective simulation minimize the wind bias but are not able to compensate for the general flow pattern biases inherited from large scale inputs. By using an alternative analyses data for initializing the meteorological simulation, the model can re-produce the flow pattern and generate the ozone peak location closer to the reality. The inaccurate simulation of precipitation and cloudiness cause over-prediction of ozone occasionally. Since there are limitations in the meteorological model to simulate precipitation and cloudiness in the fine scale domain (less than 4-km grid), the satellite-based cloud is an alternative way to provide necessary inputs for the retrospective study of air quality.

  1. The TEX-I real-time expert system, applied to situation assessment for the SNR-300 reactor

    International Nuclear Information System (INIS)

    Schmal, N.; Leder, H.J.; Schade, H.J.

    1988-01-01

    Interatom, a subsidiary company of Siemens, is developing expert systems for the technical domain. These systems are operating in various industrial applications like flexible manufacturing or plant configuration, based on a domain-specific expert system shell, developed by Interatom. Additional projects are focusing on real-time diagnostics, e.g., for nuclear power plants. The authors report in this paper about a diagnosis expert system for the liquid-metal fast breeder reactor SNR-300, which uses new real-time tools, developed within the German TEX-I project (technical expert systems for data interpretation, diagnosis, and process control). The purpose of the system is to support the reactor operators in assessing plant status in real time, based on readings from many sensors. By on-line connection to the process control computer, it can monitor all incoming signal values, check the consistency of data, continuously diagnose the current plant status, detect unusual trends prior to accidents, localize faulty components, and recommended operator response in abnormal conditions. In the present knowledge acquisition and test phase, the expert system is connected to a real-time simulation of the reactor. The simulator is based on a thermohydraulic code for simulation of the transient behavior of temperatures and flow rates in the reactor core, plena, pipes, pumps, valves, intermediate heat exchangers, and cooling components. Additionally, the system's response to an asynchronous operator interaction can be simulated

  2. Comparison of self-expandable and balloon-expanding stents for hybrid ductal stenting in hypoplastic left heart complex.

    Science.gov (United States)

    Goreczny, Sebastian; Qureshi, Shakeel A; Rosenthal, Eric; Krasemann, Thomas; Nassar, Mohamed S; Anderson, David R; Morgan, Gareth J

    2017-07-01

    We aimed to compare the procedural and mid-term performance of a specifically designed self-expanding stent with balloon-expandable stents in patients undergoing hybrid palliation for hypoplastic left heart syndrome and its variants. The lack of specifically designed stents has led to off-label use of coronary, biliary, or peripheral stents in the neonatal ductus arteriosus. Recently, a self-expanding stent, specifically designed for use in hypoplastic left heart syndrome, has become available. We carried out a retrospective cohort comparison of 69 neonates who underwent hybrid ductal stenting with balloon-expandable and self-expanding stents from December, 2005 to July, 2014. In total, 43 balloon-expandable stents were implanted in 41 neonates and more recently 47 self-expanding stents in 28 neonates. In the balloon-expandable stents group, stent-related complications occurred in nine patients (22%), compared with one patient in the self-expanding stent group (4%). During follow-up, percutaneous re-intervention related to the ductal stent was performed in five patients (17%) in the balloon-expandable stent group and seven patients (28%) in self-expanding stents group. Hybrid ductal stenting with self-expanding stents produced favourable results when compared with the results obtained with balloon-expandable stents. Immediate additional interventions and follow-up re-interventions were similar in both groups with complications more common in those with balloon-expandable stents.

  3. Quantification of hepatic flow distribution using particle tracking for patient specific virtual Fontan surgery

    Science.gov (United States)

    Yang, Weiguang; Vignon-Clementel, Irene; Troianowski, Guillaume; Shadden, Shawn; Mohhan Reddy, V.; Feinstein, Jeffrey; Marsden, Alison

    2010-11-01

    The Fontan surgery is the third and final stage in a palliative series to treat children with single ventricle heart defects. In the extracardiac Fontan procedure, the inferior vena cava (IVC) is connected to the pulmonary arteries via a tube-shaped Gore-tex graft. Clinical observations have shown that the absence of a hepatic factor, carried in the IVC flow, can cause pulmonary arteriovenous malformations. Although it is clear that hepatic flow distribution is an important determinant of Fontan performance, few studies have quantified its relation to Fontan design. In this study, we virtually implanted three types of grafts (T-junction, offset and Y-graft) into 5 patient specific models of the Glenn (stage 2) anatomy. We then performed 3D time-dependent simulations and systematically compared the IVC flow distribution, energy loss, and pressure levels in different surgical designs. A robustness test is performed to evaluate the sensitivity of hepatic distribution to pulmonary flow split. Results show that the Y-graft design effectively improves the IVC flow distribution, compared to traditional designs and that surgical designs could be customized on a patient-by-patient basis.

  4. Mechanisms of Contact Electrification at Aluminum-Polytetrafluoroethylene and Polypropylene-Water

    KAUST Repository

    Nauruzbayeva, Jamilya

    2017-04-01

    Contact electrification refers to the transfer of electrical charges between two surfaces, similar and dissimilar, as they are brought into contact and separated; this phenomenon is also known as static electrification or triboelectrification. For example, everyone has experienced weak electrical shocks from metal doorknobs, wool and synthetic clothing on dry days. While contact electrification might appear insignificant, it plays a key role in numerous natural and industrial processes, including atmospheric lightning, accumulation of dust on solar panels, charging of liquids during pipetting and flow in the tubes, and fire hazards in granular media. Contact electrification at metal-metal interfaces is well understood in terms of transfer of electrons, but a comprehensive understanding of contact electrification at interfaces of electrical insulators, such as air, water, polytetrafluoroethylene (PTFE), polypropylene remains incomplete. In fact, a variety of mechanisms responsible for transfer of electrical charges during mechanical rubbing, slipping, sliding, or flow at interfaces have been proposed via: electrons, ions, protons, hydroxide ions from water, specific orientation of dipoles, mechanoradicals, cryptoelectrons, and transfer of material. We have noticed that the extent of contact electrification of solids in water is influenced by surface free energies, mobile ions, surface roughness, duration of contact, sliding speeds, and relative humidity. Herein, we present results of our experimental investigation of contact electrification at the following interfaces: (i) PTFE-aluminum in air and (ii) polypropylene-water interfaces. To identify the underlying mechanism, we started with various hypotheses and exploited a variety of experimental techniques to falsify most of them until we got an answer; our techniques included high-voltage power supply (0-10,000 V), Faraday cages, Kelvin probe force microscopy, electrodeposition, X-ray photoelectron spectroscopy

  5. Silicified conifer forests and potential mining problems in seam M2 of the Gore Lignite Measures (Miocene), Southland, New Zealand

    Energy Technology Data Exchange (ETDEWEB)

    Lindqvist, J K; Isaac, M J [New Zealand Geological Survey, Dunedin (New Zealand). Dept. of Scientific and Industrial Research

    1991-04-01

    Silicified conifer ({ital Podocarpus cf. hallii}) stumps up to 0.8 m in diameter are present at two levels in seam M2 of the Miocene Gore Lignite Measures, Mataura Coalfield, eastern Southland. The in situ stumps are believed to be the remains of forests which grew during pauses in peat accumulation, when groundwater levels were depressed as a result of climatic change or local basinal processes. Growth-ring measurements show the trees increased in radius between 0.16 and 1 mm per year. In two of six specimens, the growth-rates halved during their final 30-40 years of life; rising water levels may have resulted in less favourable growth conditions. Within the stumps, much of the wood structure is well preserved. Progressive diagenesis involved impregnation of the cell walls by silica, infilling of the cell lumens with length-slow chalcedony and opaline silica, and deposition of opal, length-fast chalcedony, and minor siderite in fractures. Radial and axial parenchyma contain coalified organic material and minor chalcedony. Filaments of wood-rotting fungi and probable root masses of epiphytes are present in some fossil wood. However, by analogy with modern Podocarpus hallii, the stumps were probably preserved for later silicification because the wood was highly resistant to fungal and bacterial decay. The stumps presumably functioned as conduits to ascending silica-saturated meteoric groundwater and water released during compaction, because of the contrasts in permeability between the vertical stumps and the surrounding peat. 25 refs., 12 figs.

  6. Two Types of Expanding Lie Algebra and New Expanding Integrable Systems

    International Nuclear Information System (INIS)

    Dong Huanhe; Yang Jiming; Wang Hui

    2010-01-01

    From a new Lie algebra proposed by Zhang, two expanding Lie algebras and its corresponding loop algebras are obtained. Two expanding integrable systems are produced with the help of the generalized zero curvature equation. One of them has complex Hamiltion structure with the help of generalized Tu formula (GTM). (general)

  7. Technological properties of latex and natural rubber of Hevea brasiliensis clones Propriedades tecnológicas do látex e da borracha natural de clones de Hevea brasiliensis

    Directory of Open Access Journals (Sweden)

    Rogério Manoel Biagi Moreno

    2005-04-01

    Full Text Available Rubber industry has increased the requirements for quality and uniformity of natural rubber produced in Brazil. Technological properties of latex and natural rubber of clones GT 1, PB 235, IAN 873 and RRIM 600 [Hevea brasiliensis (Willd. Former Adr. de Juss. Muell.- Arg] were evaluated by standard methods of the dry rubber content (DRC%, percentage of nitrogen (N% and percentage of ashes (ASH% in two consecutive years; data were correlated with temperature and precipitation. Properties of latex and natural rubber varied (P A indústria da borracha está cada vez mais exigente em relação à qualidade e a uniformidade da borracha natural produzida no Brasil. Neste trabalho as propriedades tecnológicas do látex e da borracha natural dos clones de seringueira GT 1, PB 235, IAN 873 e RRIM 600 [Hevea brasiliensis (Willd. ex Adr. de Juss. Muell.-.Arg] foram avaliadas pelos ensaios padrões do conteúdo de borracha seca (DRC%, porcentagem de nitrogênio (N% e porcentagem de cinzas (CNZ% por dois anos consecutivos; os dados obtidos foram correlacionados com dados de temperatura e precipitação. As propriedades do látex e da borracha natural variaram (P < 0.01 em função do tipo de clone e entre coletas. O DRC% diminuiu no início da estação seca (maio a junho, enquanto N% e CNZ% aumentaram. O período de abril a junho revelou ser crítico, pois os valores da N% oscilaram acima 0,60%, fora dos padrões estabelecidos pela norma técnica brasileira ABNT/NBR. O clone RRIM 600 foi menos suscetível às variações climáticas.

  8. Influence of epoxy, polytetrafluoroethylene (PTFE) and rhodium surface coatings on surface roughness, nano-mechanical properties and biofilm adhesion of nickel titanium (Ni-Ti) archwires

    Science.gov (United States)

    Asiry, Moshabab A.; AlShahrani, Ibrahim; Almoammar, Salem; Durgesh, Bangalore H.; Kheraif, Abdulaziz A. Al; Hashem, Mohamed I.

    2018-02-01

    Aim. To investigate the effect of epoxy, polytetrafluoroethylene (PTFE) and rhodium surface coatings on surface roughness, nano-mechanical properties and biofilm adhesion of nickel titanium (Ni-Ti) archwires Methods. Three different coated (Epoxy, polytetrafluoroethylene (PTFE) and rhodium) and one uncoated Ni-Ti archwires were evaluated in the present study. Surface roughness (Ra) was assessed using a non-contact surface profilometer. The mechanical properties (nano-hardness and elastic modulus) were measured using a nanoindenter. Bacterial adhesion assays were performed using Streptococcus mutans (MS) and streptococcus sobrinus (SS) in an in-vitro set up. The data obtained were analyzed using analyses of variance, Tukey’s post hoc test and Pearson’s correlation coefficient test. Result. The highest Ra values (1.29 ± 0.49) were obtained for epoxy coated wires and lowest Ra values (0.29 ± 0.16) were obtained for the uncoated wires. No significant differences in the Ra values were observed between the rhodium coated and uncoated archwires (P > 0.05). The highest nano-hardness (3.72 ± 0.24) and elastic modulus values (61.15 ± 2.59) were obtained for uncoated archwires and the lowest nano-hardness (0.18 ± 0.10) and elastic modulus values (4.84 ± 0.65) were observed for epoxy coated archwires. No significant differences in nano-hardness and elastic modulus values were observed between the coated archwires (P > 0.05). The adhesion of Streptococcus mutans (MS) to the wires was significantly greater than that of streptococcus sobrinus (SS). The epoxy coated wires demonstrated an increased adhesion of MS and SS and the uncoated wires demonstrated decreased biofilm adhesion. The Spearman correlation test showed that MS and SS adhesion was positively correlated with the surface roughness of the wires. Conclusion. The different surface coatings significantly influence the roughness, nano-mechanical properties and biofilm adhesion parameters of the archwires. The

  9. Comparación de guantes de látex de uso clínico de diferentes marcas comerciales mediante microscopía electrónica de barrido

    Directory of Open Access Journals (Sweden)

    Gilberto González

    2015-10-01

    Full Text Available Resumen (español El uso de guantes de látex representa la primera barrera contra patógenos por parte del personal de ciencias de la salud, sin embargo, es cotidiano escuchar quejas sobre la calidad de los mismos, ya que en algunos casos tienden a romperse con facilidad disminuyendo así su capacidad protectora, además de utilizar como lubricante almidón de maíz, sustancia que puede provocar alergias. En esta investigación se compararon las características morfológicas del látex y la composición química del polvo de guantes de látex de uso clínico, de cinco marcas comerciales mediante microscopia electrónica de barrido. La calidad protectora se estableció como un arreglo entre el promedio de poros, el diámetro de los mismos y la rugosidad de la superficie. La marca Sensimedical® conto con poros de menor diámetro entre 0,1–0,7 μm, un promedio de 36,7 y superficie poco rugosa, seguida por las marcas Mc medical®, Confit®, King® y por ultimo Medac® con poros entre 0,6-2μm, un promedio de 28,1 y superficie muy rugosa. En cuanto a la composición química elemental del polvo lubricante se encontró predominio de calcio, níquel, magnesio y sodio. La presencia del sodio y magnesio puede deberse a mejorar propiedades de sudoración del usuario, pero el níquel puede generar alergias. Además otros elementos en baja proporción considerados contaminantes. Abstract (english The use of latex gloves is the first barrier against pathogens from the staff of health sciences, however, it is commonplace to hear complaints about the quality of them, since in some cases tend to break easily thus reducing their protective capacity, besides using corn starch as a lubricant, a substance that can cause allergies. In this research the morphological characteristics of latex and chemical composition of the powder latex gloves for clinical use, five trademarks by scanning electron microscopy were compared. The protective quality was established

  10. Expander for Thin-Wall Tubing

    Science.gov (United States)

    Pessin, R.

    1983-01-01

    Tool locally expands small-diameter tubes. Tube expander locally expands and deforms tube: Compressive lateral stress induced in elastomeric sleeve by squeezing axially between two metal tool parts. Adaptable to situations in which tube must have small bulge for mechanical support or flow control.

  11. 7 CFR 351.2 - Location of inspectors.

    Science.gov (United States)

    2010-01-01

    ..., Del., Duluth, Minn., Eagle Pass, Tex., El Paso, Tex., Galveston, Tex., Hidalgo, Tex., Hilo, Hawaii, Hoboken, N.J., Honolulu, Hawaii, Houston, Tex., Jacksonville, Fla., Jamaica, L.I., N.Y., Key West, Fla...

  12. In Vitro Comparison of Self-Expanding Versus Balloon-Expandable Stents in a Human Ex Vivo Model

    International Nuclear Information System (INIS)

    Grenacher, Lars; Rohde, Stefan; Gaenger, Ellen; Deutsch, Jochen; Kauffmann, Guenter W.; Richter, Goetz M.

    2006-01-01

    The objective was to compare the radial strength and expansile precision of self-expanding stents and balloon-expandable stents in a human cadaver bifurcation model. Seven different self-expanding (LUMINEXX, JOSTENT SelfX, JOSTENT SelfX hrf, Sinus-Repo, Sinus SuperFlex, Easy Wallstent, SMART) and four different balloon-expandable stent models (Palmaz, Sinus Stent, SAXX Medium, JOSTENT peripheral), each type 10 stents (total n = 110 stents) were implanted into the common iliac arteries of human cadaver corpses. The maximum stent diameter was 10 mm for all models. After stent implantation, the specimens were filled with silicone caoutchouc. After 24 h, the vascular walls including the stents were removed from the hardened casts. Diameters were taken and the weight of the cast cylinders was measured in air and in purified water to calculate the volume of the bodies (according to Archimedes Law) as a relative but precise degree for the radial strength of the implanted stents. The cylindrical casts of the self-expanding stents showed lower mean diameters (8.2 ± 1.0 mm) and mean volumes (0.60 ± 0.14 ml/cm) than in the balloon-expandable stent group (10.1 ± 0.3 mm and 0.71 ± 0.04 ml/cm, respectively; p < 0.01). The nominal maximum diameter of 10 mm was not achieved in any of the self-expanding stents, but this was achieved in more than 70% (29/40) of the balloon-expandable stent specimens (p < 0.05). The variation between achieved volumes was significantly larger in self-expanding (range: 0.23-0.78 ml/cm) than in balloon-expandable stents (range: 0.66-0.81 ml/cm; p < 0.05). Self-expanding stents presented considerably lower radial expansion force and lower degree of precision than balloon-expandable stents

  13. Effects of polytetrafluoroethylene treatment and compression on gas diffusion layer microstructure using high-resolution X-ray computed tomography

    Science.gov (United States)

    Khajeh-Hosseini-Dalasm, Navvab; Sasabe, Takashi; Tokumasu, Takashi; Pasaogullari, Ugur

    2014-11-01

    The microstructure of a TGP-H-120 Toray paper gas diffusion layer (GDL) was investigated using high resolution X-ray computed tomography (CT) technique, with a resolution of 1.8 μm and a field of view (FOV) of ∼1.8 × 1.8 mm. The images obtained from the tomography scans were further post processed, and image thresholding and binarization methodologies are presented. The validity of Otsu's thresholding method was examined. Detailed information on bulk porosity and porosity distribution of the GDL at various Polytetrafluoroethylene (PTFE) treatments and uniform/non-uniform compression pressures was provided. A sample holder was designed to investigate the effects of non-uniform compression pressure, which enabled regulating compression pressure between 0, and 3 MPa at a gas channel/current collector rib configuration. The results show the heterogeneous and anisotropic microstructure of the GDL, non-uniform distribution of PTFE, and significant microstructural change under uniform/non-uniform compression. These findings provide useful inputs for numerical models to include the effects of microstructural changes in the study of transport phenomena within the GDL and to increase the accuracy and predictability of cell performance.

  14. Development of high performance lubricant through the compatibility of polyalphaolefin, polyurea and irradiated polytetrafluoroethylene

    International Nuclear Information System (INIS)

    Ratao, Natalia Torres

    2013-01-01

    Lubricants are gaseous, liquid, semi solid or solid (powder) materials those form a film between two parties preventing friction. High performance lubricants are designed to work under severe conditions of temperature, pressure, and contamination. The most used are liquids (oils) and semi solids (greases). Greases are applied where oils can drain or in inaccessible places and are divided generally into two classes, soap and no soap. The most used non soap grease is polyurea, obtained by the reaction between amine and isocyanate, has highly thixotropic, high dielectric strength and excellent anticorrosive property, so it is widely used for lubrication of electric motors and shipbuilding machinery. For a grease with high performance, in this study was used a synthetic lubricant fluid, polyalphaolefin, and was also employed solid lubricant additive polytetrafluoroethylene (PTFE) due its lowest coefficient of friction, is found commercially irradiated in air to obtain smaller particles and to produce oxygenated terminal groups those are more compatible with the metal surface. The tests conducted were comparatively between pure polyurea grease and with PTFE additive. The characterizations were made by infrared spectroscopy and elemental analysis of C, N and H and Free NCO index, proving the formation of four carbons polyurea (tetraurea). The functional analysis of drop point and oil separation showed high stability and compatibility between the polymers increased when PTFE was added. The excellent resistance of pure tetraurea grease to wear and extreme pressure were demonstrated by four-ball and practical bearings tests, characterizing this grease as a high performance lubricant, when compared to most used greases in the market. (author)

  15. Network of anatomical texts (NAnaTex), an open-source project for visualizing the interaction between anatomical terms.

    Science.gov (United States)

    Momota, Ryusuke; Ohtsuka, Aiji

    2018-01-01

    Anatomy is the science and art of understanding the structure of the body and its components in relation to the functions of the whole-body system. Medicine is based on a deep understanding of anatomy, but quite a few introductory-level learners are overwhelmed by the sheer amount of anatomical terminology that must be understood, so they regard anatomy as a dull and dense subject. To help them learn anatomical terms in a more contextual way, we started a new open-source project, the Network of Anatomical Texts (NAnaTex), which visualizes relationships of body components by integrating text-based anatomical information using Cytoscape, a network visualization software platform. Here, we present a network of bones and muscles produced from literature descriptions. As this network is primarily text-based and does not require any programming knowledge, it is easy to implement new functions or provide extra information by making changes to the original text files. To facilitate collaborations, we deposited the source code files for the network into the GitHub repository ( https://github.com/ryusukemomota/nanatex ) so that anybody can participate in the evolution of the network and use it for their own non-profit purposes. This project should help not only introductory-level learners but also professional medical practitioners, who could use it as a quick reference.

  16. Caracterização de genótipos de tomateiro resistentes a begomovírus por marcador molecular co-dominante ligado ao gene Ty-1 Fingerprinting of tomato genotypes resistant to begomovirus by a codominant molecular marker linked to Ty-1 gene

    Directory of Open Access Journals (Sweden)

    Daniela Aparecida de Castro Nizio

    2008-12-01

    Full Text Available O objetivo deste trabalho foi avaliar genótipos de tomateiro, quanto à resistência a begomovírus, e caracterizar, por meio do marcador molecular SSR-47, híbridos de tomate de mesa portadores do alelo de resistência ao begomovírus Ty-1, com potencial comercial. Os 24 híbridos experimentais, heterozigotos no loco Ty-1, depois de infectados via enxertia, apresentaram sintomas intermediários, em comparação aos identificados pelas linhagens homozigotas Ty-1/Ty-1 e pelos genótipos suscetíveis Ty-1+/Ty-1+, o que indica a dominância incompleta do alelo Ty-1. Esses híbridos foram considerados como parcialmente tolerantes a begomovírus. Os híbridos experimentais TEX-246, TEX-261, TEX-253, TEX-256, TEX-262, TEX-252, TEX-251 e TEX-268 aliaram médias elevadas de produção total e de massa média dos frutos; e os híbridos TEX-246, TEX-253, TEX-256, TEX-262 e TEX-252 apresentaram valores elevados também para meia-vida da firmeza e foram, portanto, considerados competitivos em comparação aos padrões comerciais usados como testemunhas. O marcador molecular SSR-47 foi eficiente em caracterizar genótipos portadores do alelo Ty-1. A infecção do begomovírus, induzida via enxertia, manifestou sintomas, nos genótipos testados, condizentes com os resultados obtidos com o marcador molecular SSR-47.The objectives of this study were to evaluate tomato genotypes for begomovirus resistance and to assess SSR-47 fingerprinting patterns associated with alleles Ty-1, in hybrids of fresh-market tomato with commercial potential. Twenty-four experimental genotypes, heterozygous at Ty-1 locus, were infected with begomovirus via grafting, and showed intermediate symptoms compared to the ones identified by homozygous Ty-1/Ty-1 lines and by susceptible genotypes Ty-1+/Ty-1+, which indicates the incomplete dominance of the Ty-1 allele. These hybrids were considered to possess partial resistance to begomovirus. The experimental hybrids TEX-246, TEX-261, TEX

  17. Comparative study between immunoturbidimetric and latex agglutination methods for the detection of rheumatoid factor Estudo comparativo entre as técnicas de aglutinação em látex e de imunoturbidimetria para a detecção de fator reumatoide

    Directory of Open Access Journals (Sweden)

    Katya Cristina Rocha

    2013-02-01

    Full Text Available INTRODUCTION: The rheumatoid factor (RF is the most common antibody found in patients with rheumatoid arthritis. It is an inflammatory chronic disease characterized by articular involvement, inflammation of synovial fluid, tissue infiltration by leucocytes and joint destruction, which ultimately determine articular deformities. The rheumatoid factor is found in 70%-80% of the adult population and in 10% of the young population. OBJECTIVE: The aim of this research was to compare immunoturbidimetric and latex agglutination methods for the detection of RF in serum. RESULTS: The immunoturbidimetric method displayed sensitivity (95.2%, specificity (89.4% and high positive correlation (R² = 0,8077 with the latex agglutination method in positive serum samples. CONCLUSION: The study allowed to demonstrate that both immunoturbidimetric and latex agglutination methods equally discriminate between negative and positive serum samples for RF.INTRODUÇÃO: O fator reumatoide (FR é o autoanticorpo mais comum encontrado em pacientes com artrite reumatoide, uma doença crônica inflamatória caracterizada pelo envolvimento articular com inflamação do líquido sinovial, infiltração de tecido por leucócitos e destruição das articulações, que acaba por determinar deformidades articulares. O FR é encontrado em 70%-80% da população adulta e em 10% da população juvenil. OBJETIVO: Comparar os métodos de imunoturbidimetria e aglutinação (prova do látex para a determinação de FR em soro. RESULTADO: Foi possível observar que o método imunoturbidimétrico apresenta sensibilidade (95,2%, especificidade (89,4% e correlação positiva elevada (R² = 0,8077 com o método de aglutinação pelo látex em amostras de soro positivas. CONCLUSÃO: O estudo permitiu demonstrar que o método imunoturbidimétrico e o método de aglutinação pelo látex são igualmente capazes de discriminar amostras negativas e positivas para FR.

  18. Drastic Improvement in Adhesion Property of Polytetrafluoroethylene (PTFE) via Heat-Assisted Plasma Treatment Using a Heater.

    Science.gov (United States)

    Ohkubo, Yuji; Ishihara, Kento; Shibahara, Masafumi; Nagatani, Asahiro; Honda, Koji; Endo, Katsuyoshi; Yamamura, Kazuya

    2017-08-25

    The heating effect on the adhesion property of plasma-treated polytetrafluoroethylene (PTFE) was examined. For this purpose, a PTFE sheet was plasma-treated at atmospheric pressure while heating using a halogen heater. When plasma-treated at 8.3 W/cm 2 without using the heater (Low-P), the surface temperature of Low-P was about 95 °C. In contrast, when plasma-treated at 8.3 W/cm 2 while using the heater (Low-P+Heater), the surface temperature of Low-P+Heater was controlled to about 260 °C. Thermal compression of the plasma-treated PTFE with or without heating and isobutylene-isoprene rubber (IIR) was performed, and the adhesion strength of the IIR/PTFE assembly was measured via the T-peel test. The adhesion strengths of Low-P and Low-P+Heater were 0.12 and 2.3 N/mm, respectively. Cohesion failure of IIR occurred during the T-peel test because of its extremely high adhesion property. The surfaces of the plasma-treated PTFE with or without heating were investigated by the measurements of electron spin resonance, X-ray photoelectron spectroscopy, nanoindentation, scanning electron microscopy, and scanning probe microscopy. These results indicated that heating during plasma treatment promotes the etching of the weak boundary layer (WBL) of PTFE, resulting in a sharp increase in the adhesion property of PTFE.

  19. Comparison of Polytetrafluoroethylene Flat-Sheet Membranes with Different Pore Sizes in Application to Submerged Membrane Bioreactor

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    Manabu Motoori

    2012-06-01

    Full Text Available This study focused on phase separation of activated sludge mixed liquor by flat-sheet membranes of polytetrafluoroethylene (PTFE. A 20 liter working volume lab-scale MBR incorporating immersed PTFE flat-sheet membrane modules with different pore sizes (0.3, 0.5 and 1.0 μm was operated for 19 days treating a synthetic wastewater. The experiment was interrupted twice at days 5 and 13 when the modules were removed and cleaned physically and chemically in sequence. The pure water permeate flux of each membrane module was measured before and after each cleaning step to calculate membrane resistances. Results showed that fouling of membrane modules with 0.3 μm pore size was more rapid than other membrane modules with different pore sizes (0.5 and 1.0 μm. On the other hand, it was not clear whether fouling of the 0.5 μm membrane module was more severe than that of the 1.0 μm membrane module. This was partly because of the membrane condition after chemical cleaning, which seemed to determine the fouling of those modules over the next period. When irreversible resistance (Ri i.e., differences in membrane resistance before use and after chemical cleaning was high, the transmembrane pressure increased quickly during the next period irrespective of membrane pore size.

  20. Facile fabrication and characterization of poly(tetrafluoroethylene)@polypyrrole/nano-silver composite membranes with conducting and antibacterial property

    Science.gov (United States)

    Shi, Zhiquan; Zhou, Hui; Qing, Xutang; Dai, Tingyang; Lu, Yun

    2012-06-01

    Porous poly(tetrafluoroethylene) (PTFE) membranes play an important role in air purification and separation engineering. To achieve the bi-functionality of conducting and antibacterial property, two kinds of poly(tetrafluoroethylene)@ polypyrrole/nano-silver composite membranes have been prepared. One involves hydrophobic polypyrrole/nano-silver composite with hollow capsule nanostructures immobilized on the surface of the PTFE membranes. The other is a type of composite membranes with polypyrrole/nano-silver composite wholly packed on the fibrils of the expand PTFE membrane to form core/shell coaxial cable structures. The structure and morphology of the two kinds of composite membranes have been characterized by FTIR, UV-vis, XRD, TGA and SEM measurements. Possible formation mechanisms of the hollow capsules and the core/shell nanocable structures have been discussed in detail. The antibacterial effects of composite membranes are also briefly investigated.

  1. Histomorphometric Analysis of Periodontal Tissue Regeneration by the Use of High Density Polytetrafluoroethylen Membrane in Grade II Furcation Defects of Dogs

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    Raoofi S

    2015-09-01

    Full Text Available Statement of Problem: There are limited histomorphometric studies on biologic efficacy of high density tetrafluoroethylen (d-PTFE membrane. Objectives: To investigate the healing of surgically induced grade II furcation defects in dogs following the use of dense polytetrafluoroethylene as the barrier membrane and to compare the results with the contra lateral control teeth without the application of any membrane. Materials andMethods: Mandibular and maxillary 3rd premolar teeth of 18 young adult male mongrel dogs were used for the experiment. The furcation defects were created during the surgery. 5 weeks later, regenerative surgery was performed. The third premolar teeth were assigned randomly to control and test groups. In the test group, after a full thickness flap reflection, the d-PTFE membrane was placed over furcation defects. In the control group, no membrane was placed over the defect. 37 tissue blocks containing the teeth and surrounding hard and soft tissues were obtained three months post-regenerative surgery. The specimens were demineralized, serially sectioned, mounted and stained with Hematoxylin and Eosin staining technique. From each tissue block, 35-45 sections of 10 μm thickness within 60μm interval captured the entire surgically created defect. The histological images were transferred to computer and then the linear measurement ranges of the defects area, interadicular alveolar bone, epithelial attachment and coronal extension of the new cementum were done. Then, the volume and area of aforementioned parameters were calculated considering the thickness and interval of the sections. To compare the parameters between the control and test teeth, we calculated the amount of each one proportionally to the original amount of defects. Results: The mean interradicular root surface areas of original defects covered with new cementum was 74.46% and 29.59% for the membrane and control defects, respectively (p < 0.0001. Corresponding

  2. Microbial Biofilms and Breast Tissue Expanders

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    Melissa J. Karau

    2013-01-01

    Full Text Available We previously developed and validated a vortexing-sonication technique for detection of biofilm bacteria on the surface of explanted prosthetic joints. Herein, we evaluated this technique for diagnosis of infected breast tissue expanders and used it to assess colonization of breast tissue expanders. From April 2008 to December 2011, we studied 328 breast tissue expanders at Mayo Clinic, Rochester, MN, USA. Of seven clinically infected breast tissue expanders, six (85.7% had positive cultures, one of which grew Propionibacterium species. Fifty-two of 321 breast tissue expanders (16.2%, 95% CI, 12.3–20.7% without clinical evidence of infection also had positive cultures, 45 growing Propionibacterium species and ten coagulase-negative staphylococci. While vortexing-sonication can detect clinically infected breast tissue expanders, 16 percent of breast tissue expanders appear to be asymptomatically colonized with normal skin flora, most commonly, Propionibacterium species.

  3. Changes in methane oxidation activity and methanotrophic community composition in saline alkaline soils.

    Science.gov (United States)

    Serrano-Silva, Nancy; Valenzuela-Encinas, César; Marsch, Rodolfo; Dendooven, Luc; Alcántara-Hernández, Rocio J

    2014-05-01

    The soil of the former Lake Texcoco is a saline alkaline environment where anthropogenic drainage in some areas has reduced salt content and pH. Potential methane (CH4) consumption rates were measured in three soils of the former Lake Texcoco with different electrolytic conductivity (EC) and pH, i.e. Tex-S1 a >18 years drained soil (EC 0.7 dS m(-1), pH 8.5), Tex-S2 drained for ~10 years (EC 9.0 dS m(-1), pH 10.3) and the undrained Tex-S3 (EC 84.8 dS m(-1), pH 10.3). An arable soil from Alcholoya (EC 0.7 dS m(-1), pH 6.7), located nearby Lake Texcoco was used as control. Methane oxidation in the soil Tex-S1 (lowest EC and pH) was similar to that in the arable soil from Alcholoya (32.5 and 34.7 mg CH4 kg(-1) dry soil day(-1), respectively). Meanwhile, in soils Tex-S2 and Tex-S3, the potential CH4 oxidation rates were only 15.0 and 12.8 mg CH4 kg(-1) dry soil day(-1), respectively. Differences in CH4 oxidation were also related to changes in the methane-oxidizing communities in these soils. Sequence analysis of pmoA gene showed that soils differed in the identity and number of methanotrophic phylotypes. The Alcholoya soil and Tex-S1 contained phylotypes grouped within the upland soil cluster gamma and the Jasper Ridge, California JR-2 clade. In soil Tex-S3, a phylotype related to Methylomicrobium alcaliphilum was detected.

  4. Preparation of organic monolithic columns in polytetrafluoroethylene tubes for reversed-phase liquid chromatography

    International Nuclear Information System (INIS)

    Catalá-Icardo, M.; Torres-Cartas, S.; Meseguer-Lloret, S.; Gómez-Benito, C.; Carrasco-Correa, E.; Simó-Alfonso, E.F.; Ramis-Ramos, G.; Herrero-Martínez, J.M.

    2017-01-01

    In this work, a method for the preparation and anchoring of polymeric monoliths in a polytetrafluoroethylene (PTFE) tubing as a column housing for microbore HPLC is described. In order to assure a covalent attachment of the monolith to the inner wall of the PTFE tube, a two-step procedure was developed. Two surface etching reagents, a commercial sodium naphthalene solution (Fluoroetch"®), or mixtures of H_2O_2 and H_2SO_4, were tried and compared. Then, the obtained hydroxyl groups on the PTFE surface were modified by methacryloylation. Attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy and scanning electron microscopy (SEM) confirmed the successful modification of the tubing wall and the stable anchorage of monolith to the wall, respectively. Special emphasis was also put on the reduction of the unwanted effects of shrinking of monolith during polymerization, by using an external proper mold and by selecting the adequate monomers in order to increase the flexibility of the polymer. Poly(glycidyl methacrylate-co-divinylbenzene) monoliths were in situ synthesized by thermal polymerization within the confines of surface-vinylized PTFE tubes. The modified PTFE tubing tightly held the monolith, and the monolithic column exhibited good pressure resistance up to 20 MPa. The column performance was also evaluated via the isocratic separation of a series of alkylbenzenes in the reversed-phase mode. The optimized monolithic columns gave plate heights ranged between 70 and 80 μm. The resulting monoliths were also satisfactorily applied to the separation of proteins. - Highlights: • Successful surface etching of PTFE inner wall tubing was done. • The modified PTFE support was next methacryloylated with GMA. • Organic polymeric monolith was in situ prepared in the functionalized PTFE tube. • The monolithic columns gave suitable pressure resistance and separation of proteins.

  5. Preparation of organic monolithic columns in polytetrafluoroethylene tubes for reversed-phase liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Catalá-Icardo, M., E-mail: mocaic@qim.upv.es [Research Institute for Integrated Management of Coastal Areas, Universitat Politècnica de València, Paranimf 1, 46730, Grao de Gandía, Valencia (Spain); Torres-Cartas, S.; Meseguer-Lloret, S.; Gómez-Benito, C. [Research Institute for Integrated Management of Coastal Areas, Universitat Politècnica de València, Paranimf 1, 46730, Grao de Gandía, Valencia (Spain); Carrasco-Correa, E.; Simó-Alfonso, E.F.; Ramis-Ramos, G. [Department of Analytical Chemistry, Universitat de València, Dr. Moliner 50, 46100, Burjassot, Valencia (Spain); Herrero-Martínez, J.M., E-mail: jmherrer@uv.es [Department of Analytical Chemistry, Universitat de València, Dr. Moliner 50, 46100, Burjassot, Valencia (Spain)

    2017-04-01

    In this work, a method for the preparation and anchoring of polymeric monoliths in a polytetrafluoroethylene (PTFE) tubing as a column housing for microbore HPLC is described. In order to assure a covalent attachment of the monolith to the inner wall of the PTFE tube, a two-step procedure was developed. Two surface etching reagents, a commercial sodium naphthalene solution (Fluoroetch{sup ®}), or mixtures of H{sub 2}O{sub 2} and H{sub 2}SO{sub 4}, were tried and compared. Then, the obtained hydroxyl groups on the PTFE surface were modified by methacryloylation. Attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy and scanning electron microscopy (SEM) confirmed the successful modification of the tubing wall and the stable anchorage of monolith to the wall, respectively. Special emphasis was also put on the reduction of the unwanted effects of shrinking of monolith during polymerization, by using an external proper mold and by selecting the adequate monomers in order to increase the flexibility of the polymer. Poly(glycidyl methacrylate-co-divinylbenzene) monoliths were in situ synthesized by thermal polymerization within the confines of surface-vinylized PTFE tubes. The modified PTFE tubing tightly held the monolith, and the monolithic column exhibited good pressure resistance up to 20 MPa. The column performance was also evaluated via the isocratic separation of a series of alkylbenzenes in the reversed-phase mode. The optimized monolithic columns gave plate heights ranged between 70 and 80 μm. The resulting monoliths were also satisfactorily applied to the separation of proteins. - Highlights: • Successful surface etching of PTFE inner wall tubing was done. • The modified PTFE support was next methacryloylated with GMA. • Organic polymeric monolith was in situ prepared in the functionalized PTFE tube. • The monolithic columns gave suitable pressure resistance and separation of proteins.

  6. 8. Mujer joven con enfermedad de takayasu grave sintomática: bypass aortobicarotídeo en «y» de gore-tex

    Directory of Open Access Journals (Sweden)

    E. Rodríguez Caulo

    2010-01-01

    – La reconstrucción quirúrgica derivativa mediante bypass aortobicarotídeo se ha mostrado eficaz y segura hasta la fecha, cediendo la sintomatología de la paciente, por lo que podría utilizarse en casos similares de estenosis sintomáticas.

  7. Optimum concentration gradient of the electrocatalyst, Nafion® and poly(tetrafluoroethylene) in a membrane-electrode-assembly for enhanced performance of direct methanol fuel cells.

    Science.gov (United States)

    Liu, Jing Hua; Jeon, Min Ku; Lee, Ki Rak; Woo, Seong Ihl

    2010-12-14

    A combinatorial library of membrane-electrode-assemblies (MEAs) which consisted of 27 different compositions was fabricated to optimize the multilayer structure of direct methanol fuel cells. Each spot consisted of three layers of ink and a gradient was generated by employing different concentrations of the three components (Pt catalyst, Nafion® and polytetrafluoroethylene (PTFE)) of each layer. For quick evaluation of the library, a high-throughput optical screening technique was employed for methanol electro-oxidation reaction (MOR) activity. The screening results revealed that gradient layers could lead to higher MOR activity than uniform layers. It was found that the MOR activity was higher when the concentrations of Pt catalyst and Nafion ionomer decreased downward from the top layer to the bottom layer. On the other hand, higher MOR activity was observed when PTFE concentration increased downward from the top to the bottom layer.

  8. Emulsion Electrospinning of Polytetrafluoroethylene (PTFE) Nanofibrous Membranes for High-Performance Triboelectric Nanogenerators.

    Science.gov (United States)

    Zhao, Pengfei; Soin, Navneet; Prashanthi, Kovur; Chen, Jinkai; Dong, Shurong; Zhou, Erping; Zhu, Zhigang; Narasimulu, Anand Arcot; Montemagno, Carlo D; Yu, Liyang; Luo, Jikui

    2018-02-14

    Electrospinning is a simple, versatile technique for fabricating fibrous nanomaterials with the desirable features of extremely high porosities and large surface areas. Using emulsion electrospinning, polytetrafluoroethylene/polyethene oxide (PTFE/PEO) membranes were fabricated, followed by a sintering process to obtain pure PTFE fibrous membranes, which were further utilized against a polyamide 6 (PA6) membrane for vertical contact-mode triboelectric nanogenerators (TENGs). Electrostatic force microscopy (EFM) measurements of the sintered electrospun PTFE membranes revealed the presence of both positive and negative surface charges owing to the transfer of positive charge from PEO which was further corroborated by FTIR measurements. To enhance the ensuing triboelectric surface charge, a facile negative charge-injection process was carried out onto the electrospun (ES) PTFE subsequently. The fabricated TENG gave a stabilized peak-to-peak open-circuit voltage (V oc ) of up to ∼900 V, a short-circuit current density (J sc ) of ∼20 mA m -2 , and a corresponding charge density of ∼149 μC m -2 , which are ∼12, 14, and 11 times higher than the corresponding values prior to the ion-injection treatment. This increase in the surface charge density is caused by the inversion of positive surface charges with the simultaneous increase in the negative surface charge on the PTFE surface, which was confirmed by using EFM measurements. The negative charge injection led to an enhanced power output density of ∼9 W m -2 with high stability as confirmed from the continuous operation of the ion-injected PTFE/PA6 TENG for 30 000 operation cycles, without any significant reduction in the output. The work thus introduces a relatively simple, cost-effective, and environmentally friendly technique for fabricating fibrous fluoropolymer polymer membranes with high thermal/chemical resistance in TENG field and a direct ion-injection method which is able to dramatically improve the

  9. Obtención de anticuerpos policlonales IgY antiparvovirus canino y evaluación en un sistema de aglutinación con látex

    Directory of Open Access Journals (Sweden)

    Jannet González-Figueredo

    2015-12-01

    Full Text Available La parvovirosis canina es una de las principales infecciones que provoca gastroenteritis, fundamentalmente en cachorros, con altos índices de morbiletalidad. Los diagnosticadores más utilizados se basan en la detección de partículas virales excretadas durante la fase aguda de la enfermedad. Algunos requieren equipos especializados, lo que aumenta los costos y el tiempo de diagnóstico. Por esto, la simplificación de estos métodos con alta sensibilidad y especificidad es prioritaria. En Cuba solo se logra un diagnóstico presuntivo sin la completa confirmación de la enfermedad, principalmente por la escasez o ausencia de un medio diagnóstico en toda la red de consultorios y clínicas veterinarias, rápido, eficaz y ajustable a nuestras condiciones. Este trabajo tuvo como objetivo obtener anticuerpos policlonales IgY a partir de yema de huevo de gallina y evaluarlos mediante un sistema de látex-aglutinación, para su posible uso como terapia y principalmente en el diagnóstico. Se inmunizaron por vía intramuscular dos gallinas de raza Leghorn con una cepa atenuada de parvovirus canino (PVC tipo 2. Se aplicaron 8 inoculaciones por ave cada 15 días. Se cosecharon los huevos y se purificaron los anticuerpos por el método de sulfato de dextrana/sulfato de sodio. Se determinó el título de IgY anti-PVC por el método de Inhibición de la Hemoaglutinación (IH y con antígeno de PVC acoplado a partículas de látex de poliestireno. Por IH se obtuvo un título de IgY anti-PVC de 1:1024. Las mezclas de anticuerpos con títulos alto y medio de ambas gallinas aglutinaron con los reactivos preparados con 230 y 460 µg/mL de antígeno. La mayor intensidad de la reacción y la mejor detectabilidad correspondieron a los reactivos elaborados con los anticuerpos de mayor título.

  10. Effective treatment of benign biliary strictures with a removable, fully covered, self-expandable metal stent: A prospective, multicenter European study

    Science.gov (United States)

    Schmidt, Arthur; Pickartz, Tilman; Lerch, Markus M; Fanelli, Fabrizio; Fiocca, Fausto; Lucatelli, Pierleone; Cereatti, Fabrizio; Hoffmeister, Albrecht; van Steenbergen, Werner; Kraft, Matthias; Meier, Benjamin

    2016-01-01

    Background Temporary placement of removable, fully covered, self-expandable metal stents (fcSEMS) for treatment of benign biliary strictures (BBS) has been reported to be effective. However, the optimal extraction time point remains unclear and stent migration has been a major concern. Objective The objective of this study was to evaluate the efficacy and safety of this treatment modality using an fcSEMS with a special antimigration design and prolonged stent indwell time. Methods We performed a prospective, single-arm study at six tertiary care centers in Europe. Patients with BBS underwent endoscopic or percutaneous implantation of an fcSEMS (GORE® VIABIL® Biliary Endoprosthesis, W.L. Gore & Associates, Flagstaff, AZ, USA). The devices were scheduled to be removed nine months later, and patients were to return for follow-up for an additional 15 months. Results Forty-three patients were enrolled in the study. Stricture etiology was chronic pancreatitis in the majority of patients (57.5%). All fcSEMS were placed successfully, either endoscopically (76.7%) or percutaneously (23.3%). Stent migration was observed in two patients (5.2%). Primary patency of the SEMS prior to removal was 73.0%. All attempted stent removals were successful. At removal, stricture was resolved or significantly improved without need for further therapy in 78.9% of patients. Stricture recurrence during a follow-up of two years post-implant was observed in two patients. Conclusions Temporary placement of the fcSEMS is a feasible, safe and effective treatment for BBS. The design of the device used in this study accounts for very low migration rates and facilitates easy stent retrieval, even after it has been in place for up to 11 months. PMID:28507752

  11. Effective treatment of benign biliary strictures with a removable, fully covered, self-expandable metal stent: A prospective, multicenter European study.

    Science.gov (United States)

    Schmidt, Arthur; Pickartz, Tilman; Lerch, Markus M; Fanelli, Fabrizio; Fiocca, Fausto; Lucatelli, Pierleone; Cereatti, Fabrizio; Hoffmeister, Albrecht; van Steenbergen, Werner; Kraft, Matthias; Meier, Benjamin; Caca, Karel

    2017-04-01

    Temporary placement of removable, fully covered, self-expandable metal stents (fcSEMS) for treatment of benign biliary strictures (BBS) has been reported to be effective. However, the optimal extraction time point remains unclear and stent migration has been a major concern. The objective of this study was to evaluate the efficacy and safety of this treatment modality using an fcSEMS with a special antimigration design and prolonged stent indwell time. We performed a prospective, single-arm study at six tertiary care centers in Europe. Patients with BBS underwent endoscopic or percutaneous implantation of an fcSEMS (GORE® VIABIL® Biliary Endoprosthesis, W.L. Gore & Associates, Flagstaff, AZ, USA). The devices were scheduled to be removed nine months later, and patients were to return for follow-up for an additional 15 months. Forty-three patients were enrolled in the study. Stricture etiology was chronic pancreatitis in the majority of patients (57.5%). All fcSEMS were placed successfully, either endoscopically (76.7%) or percutaneously (23.3%). Stent migration was observed in two patients (5.2%). Primary patency of the SEMS prior to removal was 73.0%. All attempted stent removals were successful. At removal, stricture was resolved or significantly improved without need for further therapy in 78.9% of patients. Stricture recurrence during a follow-up of two years post-implant was observed in two patients. Temporary placement of the fcSEMS is a feasible, safe and effective treatment for BBS. The design of the device used in this study accounts for very low migration rates and facilitates easy stent retrieval, even after it has been in place for up to 11 months.

  12. Low-Pressure H2, NH3 Microwave Plasma Treatment of Polytetrafluoroethylene (PTFE) Powders: Chemical, Thermal and Wettability Analysis

    Science.gov (United States)

    Hunke, Harald; Soin, Navneet; Shah, Tahir H.; Kramer, Erich; Pascual, Alfons; Karuna, Mallampalli Sri Lakshmi; Siores, Elias

    2015-01-01

    Functionalization of Polytetrafluoroethylene (PTFE) powders of ~6 μm particle size is carried out using low-pressure 2.45 GHz H2, NH3 microwave plasmas for various durations (2.5, 10 h) to chemically modify their surface and alter their surface energy. The X-ray Photoelectron Spectroscopy (XPS) analyses reveal that plasma treatment leads to significant defluorination (F/C atomic ratio of 1.13 and 1.30 for 10 h NH3 and H2 plasma treatments, respectively vs. 1.86 for pristine PTFE), along with the incorporation of functional polar moieties on the surface, resulting in enhanced wettability. Analysis of temperature dependent XPS revealed a loss of surface moieties above 200 °C, however, the functional groups are not completely removable even at higher temperatures (>300 °C), thus enabling the use of plasma treated PTFE powders as potential tribological fillers in high temperature engineering polymers. Ageing studies carried over a period of 12 months revealed that while the surface changes degenerate over time, again, they are not completely reversible. These functionalised PTFE powders can be further used for applications into smart, high performance materials such as tribological fillers for engineering polymers and bio-medical, bio-material applications.

  13. The effect of irradiation atmosphere on NMR absorption of 60Co γ-rays irradiated polytetrafluoroethylene

    International Nuclear Information System (INIS)

    Tutiya, Mituaki

    1975-01-01

    The radiation stability of polytetrafluoroethylene (PTFE) is sensitive to the presence of oxygen during irradiation. In semicrystalline polymers such as PTFE, it is expected that the influence of irradiation differs in crystalline and amorphous regions, therefore the magnitude of irradiation effect in amorphous region was compared with that in crystalline region of PTFE. In the NMR measurement by the author, the main difference between the PTFE samples annealed after irradiation in air and in vacuum was that the increase in crystallinity and the lowering of crystalline transition temperature Tsub(t) were accelerated in the former case. The scission probability of C-C bonds r can be estimated from the radiation-induced increase in crystallinity in the amorphous region of PTFE, and the value of r in the crystalline region can also be calculated. According to previous papers, the ratio of the scission probability in air to that in vacuum was estimated to be about 7 in the amorphous region and 1.8 in the crystalline region of PTFE. From this fact, the following conclusions were drawn. Main chain scission was accelerated when PTFE was irradiated in air. In PTFE, the amorphous region was affected more by irradiation atmosphere than the crystalline region. In both air and vacuum irradiation, the scission probability in the amorphous region was larger than that in the crystalline region. The effect of irradiation on PTFE was affected by oxygen diffusion, the life time of free radicals, and the degree of packing of molecular chains. (Kako, I.)

  14. Suspended polytetrafluoroethylene nanostructure electret film in dual variable cavities for self-powered micro-shock sensing

    Science.gov (United States)

    Zhu, Jianxiong; Chen, Cong; Guo, Xiaoyu

    2018-04-01

    We report a suspended polytetrafluoroethylene (PTFE) nanostructure electret film in dual variable cavities for a self-powered micro-shock sensing application. The prototype contained series variable air cavities, a suspended nanostructure PTFE electret film and independent electrode films. The charges on the suspended nanostructure PTFE electret film provided the electrostatic field around the electret film in the series variable air cavities. When the reported device was driven by a micro-shock pressure, the inducted electrostatic charges on both the top and bottom electrodes would vary as the micro-shock pressing or releasing. Experimental results showed that the maximum of a short-circuit current density (J sc ) and an open-circuit voltage (V oc ) reached 3 ± 0.1 nA cm‑2 and 3.6 ± 0.1 V, respectively. It was found that the parameter J sc was more advantageous in identifying stronger shocks (parameter acceleration a bigger than 0.1 m s‑2), whereas the parameter V oc was more sensitive for weaker shocks, such as acceleration a smaller than 0.1 m s‑2. Moreover, finger continuous micro-shock pressure taps application was used to demonstrate the mechanical energy conversion performance with 4.5 ± 0.2 V open-circuit voltages. The research on the nanostructure electret PTFE film in series dual variable air cavities not only gave us a fresh idea about the principle and design of the shocking sensor, but also provided an easy fabrication and a low cost shocking sensor for the Internet of Things (IoT) systems.

  15. Silicon microfabricated beam expander

    Science.gov (United States)

    Othman, A.; Ibrahim, M. N.; Hamzah, I. H.; Sulaiman, A. A.; Ain, M. F.

    2015-03-01

    The feasibility design and development methods of silicon microfabricated beam expander are described. Silicon bulk micromachining fabrication technology is used in producing features of the structure. A high-precision complex 3-D shape of the expander can be formed by exploiting the predictable anisotropic wet etching characteristics of single-crystal silicon in aqueous Potassium-Hydroxide (KOH) solution. The beam-expander consist of two elements, a micromachined silicon reflector chamber and micro-Fresnel zone plate. The micro-Fresnel element is patterned using lithographic methods. The reflector chamber element has a depth of 40 µm, a diameter of 15 mm and gold-coated surfaces. The impact on the depth, diameter of the chamber and absorption for improved performance are discussed.

  16. Bigelow Expandable Activity Module Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Bigelow Expandable Activity Module (BEAM) project is a NASA-industry partnership with Bigelow Aerospace (BA) that has developing the first human-rated expandable...

  17. Fabrication of TiO{sub 2}-modified polytetrafluoroethylene ultrafiltration membranes via plasma-enhanced surface graft pretreatment

    Energy Technology Data Exchange (ETDEWEB)

    Qian, Yingjia [School of Environmental Science and Engineering, Shanghai Jiaotong University, Shanghai 200240 (China); Chi, Lina, E-mail: lnchi@sjtu.edu.cn [School of Environmental Science and Engineering, Shanghai Jiaotong University, Shanghai 200240 (China); Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ (United Kingdom); Zhou, Weili; Yu, Zhenjiang [School of Environmental Science and Engineering, Shanghai Jiaotong University, Shanghai 200240 (China); Zhang, Zhongzhi [College of Chemical Engineering, China University of Petroleum, Beijing 102249 (China); Zhang, Zhenjia [School of Environmental Science and Engineering, Shanghai Jiaotong University, Shanghai 200240 (China); Jiang, Zheng, E-mail: z.jiang@soton.ac.uk [Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ (United Kingdom)

    2016-01-01

    Graphical abstract: - Highlights: • Multifunctional TiO{sub 2}/PAA/PTFE ultrafiltration membrane was fabricated via tight coating of TiO{sub 2} functional layer onto the plasma-assisted graft of PAA on PTFE. • The high water flux rate, remarkable enhanced ultrafiltration performance and excellent self-cleaning ability were demonstrated. • The formation of COO−Ti bidentate coordination between TiO{sub 2} and PAA was responsible for the successful coating. - Abstract: Surface hydrophilic modification of polymer ultrafiltration membrane using metal oxide represents an effective yet highly challenging solution to improve water flux and antifouling performance. Via plasma-enhanced graft of poly acryl acid (PAA) prior to coating TiO{sub 2}, we successfully fixed TiO{sub 2} functional thin layer on super hydrophobic polytetrafluoroethylene (PTFE) ultrafiltration (UF) membranes. The characterization results evidenced TiO{sub 2} attached on the PTFE-based UF membranes through the chelating bidentate coordination between surface-grafted carboxyl group and Ti{sup 4+}. The TiO{sub 2} surface modification may greatly reduce the water contact angle from 115.8° of the PTFE membrane to 35.0° without degradation in 30-day continuous filtration operations. The novel TiO{sub 2}/PAA/PTFE membranes also exhibited excellent antifouling and self-cleaning performance due to the intrinsic hydrophilicity and photocatalysis properties of TiO{sub 2}, which was further confirmed by the photo-degradation of MB under Xe lamp irradiation.

  18. Effect of polytetrafluoroethylene (PTFE) phase transition at 19°C on the use of Spectralon as a reference standard for reflectance.

    Science.gov (United States)

    Ball, Christopher P; Levick, Andrew P; Woolliams, Emma R; Green, Paul D; Dury, Martin R; Winkler, Rainer; Deadman, Andrew J; Fox, Nigel P; King, Martin D

    2013-07-10

    Sintered polytetrafluoroethylene (PTFE) is highly reflective and is widely used as a reference standard in remote sensing, radiometry, and spectroscopy. The relative change in output flux from a PTFE integrating sphere over the room temperature phase transition at 19°C has been measured at a monochromatic wavelength of 633 nm as 1.82±0.21%. The change in output flux was attributed to a small change of 0.09±0.02% in the total hemispherical reflectance of PTFE, caused by a change in its material density as a result of the phase transition. For the majority of users, this small change measured in total hemispherical reflectance is unlikely to impact significantly the accuracy of PTFE flat panel reflectors used as reference standards. However, owing to the multiple reflections that occur inside an integrating sphere cavity, the effect is multiplied and remedial action should be applied, either via a mathematical correction or through temperature stabilization of the integrating sphere when high accuracy (PTFE-based integrating spheres at temperatures close to the phase transition at 19°C.

  19. Efficacy of linezolid, teicoplanin, and vancomycin in prevention of an experimental polytetrafluoroethylene graft infection model caused by methicillin-resistant Staphylococcus aureus.

    Science.gov (United States)

    Mese, Bulent; Bozoglan, Orhan; Elveren, Serdal; Eroglu, Erdinc; Gul, Mustafa; Celik, Ahmet; Ciralik, Harun; Yildirimdemir, Halil Ibrahim; Yasim, Alptekin

    2015-03-27

    The aim of this study was to evaluate the effectiveness of linezolid, teicoplanin, and vancomycin in prevention of prosthetic vascular graft infections in a vascular graft infection model. Fifty rats were divided into 5 groups. A polytetrafluoroethylene graft was implanted on the back of each rat. Methicillin-resistant Staphylococcus aureus (MRSA) strain was inoculated into all rats except Group 1. Group 2 was not given any treatment, Group 3 received linezolid, Group 4 received vancomycin, and Group 5 received teicoplanin. The grafts were removed for microbiological and histological examinations on the 7th day. In addition, C-reactive protein and prealbumin levels and leukocyte counts in obtained blood specimens were determined. Group 1 did not have infection. Group 2 had bacteria 5.7 × 10(4) CFU/cm(2). Group 3 and Group 4 had less bacterial growth. Group 5 had no bacterial growth. The number of bacteria was significantly higher in Group 2 than in the other experimental groups and the control group (pprevention of prosthetic vascular graft infections.

  20. Helium turbo-expander with an alternator

    International Nuclear Information System (INIS)

    Akiyama, Yoshitane

    1980-01-01

    Study was made on a helium turbo-expander, the heart of helium refrigerator systems, in order to develop a system which satisfies the required conditions. A helium turbo-expander with externally pressurized helium gas bearings at the temperature of liquid nitrogen and an alternator as a brake have been employed. The essential difference between a helium turbo-expander and a nitrogen turbo-expander was clarified. The gas bearing lubricated with nitrogen at room temperature and the gas bearing lubricated with helium at low temperature were tested. The flow rate of helium in a helium refrigerator for a large superconducting magnet is comparatively small, therefore a helium turbine must be small, but the standard for large turbine design can be applied to such small turbine. Using the alternator as a brake, the turbo-expander was easily controllable electrically. The prototype turbo-expander was made, and the liquefaction test with it and MHD power generation test were carried out. (Kako, I.)

  1. Silicon microfabricated beam expander

    International Nuclear Information System (INIS)

    Othman, A.; Ibrahim, M. N.; Hamzah, I. H.; Sulaiman, A. A.; Ain, M. F.

    2015-01-01

    The feasibility design and development methods of silicon microfabricated beam expander are described. Silicon bulk micromachining fabrication technology is used in producing features of the structure. A high-precision complex 3-D shape of the expander can be formed by exploiting the predictable anisotropic wet etching characteristics of single-crystal silicon in aqueous Potassium-Hydroxide (KOH) solution. The beam-expander consist of two elements, a micromachined silicon reflector chamber and micro-Fresnel zone plate. The micro-Fresnel element is patterned using lithographic methods. The reflector chamber element has a depth of 40 µm, a diameter of 15 mm and gold-coated surfaces. The impact on the depth, diameter of the chamber and absorption for improved performance are discussed

  2. Silicon microfabricated beam expander

    Energy Technology Data Exchange (ETDEWEB)

    Othman, A., E-mail: aliman@ppinang.uitm.edu.my; Ibrahim, M. N.; Hamzah, I. H.; Sulaiman, A. A. [Faculty of Electrical Engineering, Universiti Teknologi MARA Malaysia, 40450, Shah Alam, Selangor (Malaysia); Ain, M. F. [School of Electrical and Electronic Engineering, Engineering Campus, Universiti Sains Malaysia, Seri Ampangan, 14300,Nibong Tebal, Pulau Pinang (Malaysia)

    2015-03-30

    The feasibility design and development methods of silicon microfabricated beam expander are described. Silicon bulk micromachining fabrication technology is used in producing features of the structure. A high-precision complex 3-D shape of the expander can be formed by exploiting the predictable anisotropic wet etching characteristics of single-crystal silicon in aqueous Potassium-Hydroxide (KOH) solution. The beam-expander consist of two elements, a micromachined silicon reflector chamber and micro-Fresnel zone plate. The micro-Fresnel element is patterned using lithographic methods. The reflector chamber element has a depth of 40 µm, a diameter of 15 mm and gold-coated surfaces. The impact on the depth, diameter of the chamber and absorption for improved performance are discussed.

  3. Skin maintenance in the bed-ridden patient.

    Science.gov (United States)

    Flam, E

    1990-01-01

    The skin of a patient at risk of developing pressure ulcers can resist deterioration if the conditions that weaken it are controlled. The purpose of this study is to determine the relationships between hydration level, skin temperature, and friction in patients at risk of development or reoccurrence of pressure ulcers and in patients with newly created surgical flaps. Two systems were considered: the standard hospital mattress covered with a thick occlusive plastic film and a 50/50 cotton/polyester bed sheet and the KinAir and the TheraPulse support systems with nylon/High Air Loss GORE-TEX (n/HAL) laminate cushions and coverlets. The moisture vapor management and aeration capabilities of the support system materials were determined, and the frictional force generated against the skin was measured. The results revealed that excessive hydration increases the level of friction against the skin while at the same time reducing the mechanical properties of the protective skin layers. The n/HAL laminate coverlet also had a significantly lower skin friction coefficient than the 50/50 cotton/polyester bed sheet. The significance of these findings is that over-hydration accelerates the abrading action on the skin by increasing the frictional force and decreasing the shear resistance of the skin.

  4. Hole-Collection Mechanism in Passivating Metal-Oxide Contacts on Si Solar Cells: Insights From Numerical Simulations

    KAUST Repository

    Vijayan, Ramachandran Ammapet

    2018-02-14

    Silicon heterojunction solar cells enable high conversion efficiencies, thanks to their passivating contacts which consist of layered stacks of intrinsic and doped amorphous silicon. However, such contacts may reduce the photo current, when present on the illuminated side of the cell. This motivates the search for wider bandgap contacting materials, such as metal oxides. In this paper, we elucidate the precise impact of the material parameters of MoO<tex>$_{x}$> on device characteristics, based on numerical simulations. The simulation results allow us to propose design principles for hole-collecting induced junctions. We find that if MoO<tex>$_{x}$> has a sufficiently high electron affinity (<tex>$\\\\ge\\\\! \\\\text{{5.7 eV}}$tex>), direct band-to-band tunneling is the dominant transport mechanism; whereas if it has a lower electron affinity (<tex>$ <\\\\! \\\\text{{5.7 eV}}$tex>), trap-assisted tunneling dominates, which might introduce additional series resistance. At even lower electron affinity, S-shaped J–V curves may appear for these solar cells, which are found to be due to an insufficient trap state density in the MoO<tex>$_{x}$> film in contrast to the expectation of better performance at low trap density. These traps may assist carrier transport when present near the conduction band edge of the MoO<tex>$_{x}$> film. Our simulations predict that performance optimization for the MoO<tex>$_{x}$> film has to target either 1) a high electron affinity and a moderate doping density film or, 2) if the electron affinity is lower than the optimum value, a high defect density not exceeding the doping density inside the film.

  5. Surgical treatment of tetralogy of Fallot with absent pulmonary valve syndrome.

    Science.gov (United States)

    Tanaka, Yuki; Miyamoto, Takashi; Naito, Yuji; Yoshitake, Shuichi

    2016-06-01

    The patient was a 3-month-old girl weighting 3.6 kg, diagnosed with tetralogy of Fallot and absent pulmonary valve syndrome. We surgically repaired the tetralogy of Fallot by patch closure of the ventricular septal defect, right ventricular outflow tract reconstruction using an expanded polytetrafluoroethylene monocusp patch with a bulging sinus, and removal of the bronchial obstruction by anterior translocation of the pulmonary artery using the Lecompte maneuver. © The Author(s) 2015.

  6. Intercomparison of Volatile Organic Carbon Measurement Techniques and Data at La Porte During the TexAQS2000 Air Quality Study

    Energy Technology Data Exchange (ETDEWEB)

    Kuster, W. C.; Jobson, B Tom T.; Karl, Thomas G.; Riemer, D.; Apel, Eric; Goldan, P. D.; Fehsenfeld, Fred C.

    2004-01-01

    The Texas Air Quality Study 2000 (TexAQS2000) investigated the photochemical production of ozone and the chemistry of related precursors and reaction products in the vicinity of Houston, Texas. The co-location of four instruments for the measurement of volatile organic carbon compounds (VOCs) allowed a unique opportunity for the intercomparison of the different in-situ measuring techniques. The instruments included three gas chromatographs, each with a different type of detector, and a Proton-Transfer-Reaction Mass Spectrometer (PTR-MS) with each system designed to measure a different suite of VOCs. Correlation plots and correlation statistics are presented for species measured by more than one of these instruments. The GC instruments were all in agreement to within 10-20% (slope) with coefficients of variation (r2) of {ge} 0.85. The PTR-MS agreement with other instruments was more dependent on species with some very good agreements (r2 values of {approx}0.95 for some aromatics) but isoprene, acetaldehyde and propene were substantially less highly correlated (0.55 < r2 < 0.80). At least part of these differences were undoubtedly due to the timing of sample acquisition in an environment in which VOC levels changed very rapidly on both quantitative and temporal scales.

  7. Simultaneous and long-lasting hydrophilization of inner and outer wall surfaces of polytetrafluoroethylene tubes by transferring atmospheric pressure plasmas

    International Nuclear Information System (INIS)

    Chen, Faze; Song, Jinlong; Huang, Shuai; Xu, Wenji; Sun, Jing; Liu, Xin; Xu, Sihao; Xia, Guangqing; Yang, Dezheng

    2016-01-01

    Plasma hydrophilization is a general method to increase the surface free energy of materials. However, only a few works about plasma modification focus on the hydrophilization of tube inner and outer walls. In this paper, we realize simultaneous and long-lasting plasma hydrophilization on the inner and outer walls of polytetrafluoroethylene (PTFE) tubes by atmospheric pressure plasmas (APPs). Specifically, an Ar atmospheric pressure plasma jet (APPJ) is used to modify the PTFE tube’s outer wall and meanwhile to induce transferred He APP inside the PTFE tube to modify its inner wall surface. The optical emission spectrum (OES) shows that the plasmas contain many chemically active species, which are known as enablers for various applications. Water contact angle (WCA) measurements, x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) are used to characterize the plasma hydrophilization. Results demonstrate that the wettability of the tube walls are well improved due to the replacement of the surface fluorine by oxygen and the change of surface roughness. The obtained hydrophilicity decreases slowly during more than 180 d aging, indicating a long-lasting hydrophilization. The results presented here clearly demonstrate the great potential of transferring APPs for surface modification of the tube’s inner and outer walls simultaneously. (paper)

  8. Expander Codes

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 10; Issue 1. Expander Codes - The Sipser–Spielman Construction. Priti Shankar. General Article Volume 10 ... Author Affiliations. Priti Shankar1. Department of Computer Science and Automation, Indian Institute of Science Bangalore 560 012, India.

  9. Surface modification of poly(tetrafluoroethylene) films by low energy Ar+ ion-beam activation and UV-induced graft copolymerization

    International Nuclear Information System (INIS)

    Zhang Yan; Huan, A.C.H.; Tan, K.L.; Kang, E.T.

    2000-01-01

    Surface modification of poly(tetrafluoroethylene) (PTFE) films by Ar + ion-beam irradiation with varying ion energy and ion dose was carried out. The changes in surface composition of the irradiated PTFE films were characterized, both in situ and after exposure to air, by X-ray photoelectron spectroscopy (XPS). The possible mechanisms of chemical reaction induced by the incident ion beam on the surface of PTFE film included defluorination, chain scission and cross-linking, as indicated by the presence of the characteristic peak components associated with the - - -CF 3 , - - -CF, and C(CF 2 ) 4 species in the C 1s core-level spectra, the decrease in surface [F]/[C] ratio, and the increase in surface micro-hardness of the Ar + ion-beam-treated PTFE films. Furthermore, the free radicals generated by the ion-beam could react with oxygen in the air to give rise to oxidized carbon species, such as the peroxides, on the PTFE surface. Thus, after exposure to air, the Ar + ion-beam-pretreated PTFE films were susceptible to further surface modification by UV-induced graft copolymerization with a vinyl monomer, such as acrylamide (AAm). The graft concentrations were deduced from the XPS-derived surface stoichiometries. The Ar + ion energy and the ion dose affected not only the surface composition of the treated films but also the graft copolymerization efficiency of the corresponding pretreated films

  10. Bioactive surface modifications on inner walls of poly-tetra-fluoro-ethylene tubes using dielectric barrier discharge

    Science.gov (United States)

    Cho, Yong Ki; Park, Daewon; Kim, Hoonbae; Lee, Hyerim; Park, Heonyong; Kim, Hong Ja; Jung, Donggeun

    2014-03-01

    Bioactive surface modification can be used in a variety of medical polymeric materials in the fields of biochips and biosensors, artificial membranes, and vascular grafts. In this study, the surface modification of the inner walls of poly-tetra-fluoro-ethylene (PTFE) tubing was carried out to improve vascular grafts, which are made of biocompatible material for the human body in the medical field. Focus was centered on the cell attachment of the inner wall of the PTFE by sequential processes of hydrogen plasma treatment, hydrocarbon deposition, and reactive plasma treatment on the PFTE surface using micro plasma discharge. Micro plasma was generated by a medium-frequency alternating current high-voltage generator. The preliminary modification of PTFE was conducted by a plasma of hydrogen and argon gases. The hydrocarbon thin film was deposited on modified PTFE with a mixture of acetylene and argon gases. The reactive plasma treatment using oxygen plasma was done to give biocompatible functionality to the inner wall surface. The hydrophobic surface of bare PTFE is made hydrophilic by the reactive plasma treatment due to the formation of carbonyl groups on the surface. The reactive treatment could lead to improved attachment of smooth muscle cells (SMCs) on the modified PTFE tubing. Fourier transform infrared absorption spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and water contact angle measurement were used for the analysis of the surface modification. The SMC-attached PTFE tube developed will be applicable to in vitro human vasculature-mimetic model systems, and to medical vascular grafts.

  11. The expanding universe: an introduction

    OpenAIRE

    Pössel, Markus

    2017-01-01

    An introduction to the physics and mathematics of the expanding universe, using no more than high-school level / undergraduate mathematics. Covered are the basics of scale factor expansion, the dynamics of the expanding universe, various distance concepts and the generalized redshift-luminosity relation, among other topics.

  12. Tumor-Derived Exosomes and Their Role in Tumor-Induced Immune Suppression

    Directory of Open Access Journals (Sweden)

    Theresa L. Whiteside

    2016-10-01

    Full Text Available Tumor-derived exosomes (TEX are emerging as critical components of an intercellular information network between the tumor and the host. The tumor escapes from the host immune system by using a variety of mechanisms designed to impair or eliminate anti-tumor immunity. TEX carrying a cargo of immunoinhibitory molecules and factors represent one such mechanism. TEX, which are present in all body fluids of cancer patients, deliver negative molecular or genetic signals to immune cells re-programming their functions. Although TEX can also stimulate immune activity, in the microenvironments dominated by the tumor, TEX tend to mediate immune suppression thus promoting tumor progression. The TEX content, in part resembling that of the parent cell, may serve as a source of cancer biomarkers. TEX also interfere with immune therapies. A better understanding of TEX and their contribution to cancer progression and cancer patients’ response to immune therapies represents a challenging new field of investigation.

  13. A Rapidly Expanding Bose-Einstein Condensate: An Expanding Universe in the Lab

    Science.gov (United States)

    Eckel, S.; Kumar, A.; Jacobson, T.; Spielman, I. B.; Campbell, G. K.

    2018-04-01

    We study the dynamics of a supersonically expanding, ring-shaped Bose-Einstein condensate both experimentally and theoretically. The expansion redshifts long-wavelength excitations, as in an expanding universe. After expansion, energy in the radial mode leads to the production of bulk topological excitations—solitons and vortices—driving the production of a large number of azimuthal phonons and, at late times, causing stochastic persistent currents. These complex nonlinear dynamics, fueled by the energy stored coherently in one mode, are reminiscent of a type of "preheating" that may have taken place at the end of inflation.

  14. Utilization of d-PTFE Barriers for Post-Extraction Bone Regeneration in Preparation for Dental Implants.

    Science.gov (United States)

    Greenstein, Gary; Carpentieri, Joseph R

    2015-01-01

    Guided bone regeneration (GBR) can be used to restore a defective alveolar ridge after extractions before or in combination with implant placement. It may also be employed after extractions to reduce crestal bone resorption and maximize bone fill of sockets. Resorbable or nonresorbable barriers (eg, expanded polytetrafluoroethylene [e-PTFE]) can be used when performing GBR procedures, but they need to be completely submerged to attain optimal results. Dense polytetrafluoroethylene (d-PTFE) is a type of nonresorbable barrier that circumvents the necessity to attain primary closure after placement of bone grafts, thereby reducing patient morbidity. This article addresses topics pertaining to d-PTFE utilization, including characteristics and advantages of d-PTFE barriers, time needed for osteoid tissue to become impervious to penetration by flap connective tissue, relevant clinical studies, and limitations of available data. Clinical photographs and radiographs of successfully treated cases are presented to illustrate the efficacy of d-PTFE barriers in regenerating defective bony plates after extractions.

  15. Testing the Role of Microbial Ecology, Redox-Mediated Deep Water Production and Hypersalinity on TEX86: Lipids and 16s Sequences from Archaea and Bacteria in the Water Column and Sediments of Orca Basin

    Science.gov (United States)

    Warren, C.; Romero, I.; Ellis, G.; Goddard, E.; Krishnan, S.; Nigro, L. M.; Super, J. R.; Zhang, Y.; Zhuang, G.; Hollander, D. J.; Pagani, M.

    2014-12-01

    Mesophilic marine archaea and bacteria are known to substantially contribute to the oceanic microbial biomass and play critical roles in global carbon, nitrogen and nutrient cycles. The Orca Basin, a 2400 meter deep bathymetric depression on the continental slope of the north-central Gulf of Mexico, is an ideal environment to examine how redox-dependent biochemical processes control the input and cycling of bacterial and archaea-derived lipid compounds from formation in near-surface water, through secondary recycling processes operating at the redox-transition in the water column, to sedimentary diagenetic processes operating in oxic to anoxic zones within the basin. The lowermost 180 meters of the Orca Basin is characterized by an anoxic, hypersaline brine that is separated from the overlying oxic seawater by a well-defined redox sequence associated with a systematic increasing in salinity from 35 - 250‰. While surface water conditions are viewed as normal marine with a seasonally productive water column, the sub-oxic to anoxic transition zones within the deep-water column and the sediment spans over 200 m allowing the unique opportunity for discrete sampling of resident organisms and lipids. Here we present 16s rRNA sequence data of Bacteria and Archaea collected parallel to GDGT lipid profiles and in situ environmental measurements from the sediment and overlying water column in the intermediate zone of the basin, where movements of chemical transition zones are preserved. We evaluated GDGTs and corresponding taxa across the surface water, chlorophyll maximum, thermocline, and the deep redox boundary, including oxygenation, denitrification, manganese, iron and sulfate reduction zones, to determine if GDGTs are being produced under these conditions and how surface-derived GDGT lipids and the TEX86 signal may be altered. The results have implications for the application of the TEX86 paleotemperature proxy.

  16. Human testis-expressed sequence 101 is limitedly distributed in germinal epithelium of testis and disappears in seminoma

    Directory of Open Access Journals (Sweden)

    Cong-Cong Shen

    2014-01-01

    Full Text Available BACKGROUND: Testis-expressed sequence 101 (TEX101 was found to be highly expressed in testis and involved in acrosome reaction in previous studies. Recently, the metastasis suppressor function of TEX101 in cancer was disclosed, but the comprehensive investigation of its expression has rarely been reported. In this study, the expression features of TEX101 in normal human organs and seminoma were systematically analyzed. RESULTS: Immunohistochemistry demonstrated intense staining of TEX101 in human testis tissues; however, its expression in 27 other types of normal human organs, including the ovary, was negligible. Higher expression of TEX101 was observed in the spermatocytes and spermatids of the testis, but relatively lower staining was detected in spermatogonia. Western blotting showed a single TEX101 band of 38 kDa in human testis, but it did not correspond to the predicted molecular weight of its mature form at 21 KDa. Furthermore, we examined seminoma tissues by immunohistochemistry and found that none of the 36 samples expressed TEX101. CONCLUSIONS: Our data confirmed TEX101 to be a testis protein that could be related to the maturation process of male germ cells. The lack of TEX101 in seminoma indicated its potential role in tumor progression. This characteristic expression of TEX101 could provide a valuable reference for understanding its biological functions.

  17. A Rapidly Expanding Bose-Einstein Condensate: An Expanding Universe in the Lab

    Directory of Open Access Journals (Sweden)

    S. Eckel

    2018-04-01

    Full Text Available We study the dynamics of a supersonically expanding, ring-shaped Bose-Einstein condensate both experimentally and theoretically. The expansion redshifts long-wavelength excitations, as in an expanding universe. After expansion, energy in the radial mode leads to the production of bulk topological excitations—solitons and vortices—driving the production of a large number of azimuthal phonons and, at late times, causing stochastic persistent currents. These complex nonlinear dynamics, fueled by the energy stored coherently in one mode, are reminiscent of a type of “preheating” that may have taken place at the end of inflation.

  18. Endovascular Treatment of a Giant Superior Mesenteric Artery Pseudoaneurysm Using a Nitinol Stent-Graft

    International Nuclear Information System (INIS)

    Gandini, Roberto; Pipitone, Vincenzo; Konda, Daniel; Pendenza, Gianluca; Spinelli, Alessio; Stefanini, Matteo; Simonetti, Giovanni

    2005-01-01

    A 68-year-old woman presenting with gastrointestinal bleeding (hematocrit 19.3%) and in a critical clinical condition (American Society of Anesthesiologists grade 4) from a giant superior mesenteric artery pseudoaneurysm (196.0 x 131.4 mm) underwent emergency endovascular treatment. The arterial tear supplying the pseudoaneurysm was excluded using a 5.0 mm diameter and 31 mm long monorail expanded polytetrafluoroethylene (ePTFE)-covered self-expanding nitinol stent. Within 6 days of the procedure, a gradual increase in hemoglobin levels and a prompt improvement in the clinical condition were observed. Multislice CT angiograms performed immediately, 5 days, 30 days and 3 months after the procedure confirmed the complete exclusion of the pseudoaneurysm

  19. Development of Non-Optimum Factors for Launch Vehicle Propellant Tank Bulkhead Weight Estimation

    Science.gov (United States)

    Wu, K. Chauncey; Wallace, Matthew L.; Cerro, Jeffrey A.

    2012-01-01

    Non-optimum factors are used during aerospace conceptual and preliminary design to account for the increased weights of as-built structures due to future manufacturing and design details. Use of higher-fidelity non-optimum factors in these early stages of vehicle design can result in more accurate predictions of a concept s actual weights and performance. To help achieve this objective, non-optimum factors are calculated for the aluminum-alloy gores that compose the ogive and ellipsoidal bulkheads of the Space Shuttle Super-Lightweight Tank propellant tanks. Minimum values for actual gore skin thicknesses and weld land dimensions are extracted from selected production drawings, and are used to predict reference gore weights. These actual skin thicknesses are also compared to skin thicknesses predicted using classical structural mechanics and tank proof-test pressures. Both coarse and refined weights models are developed for the gores. The coarse model is based on the proof pressure-sized skin thicknesses, and the refined model uses the actual gore skin thicknesses and design detail dimensions. To determine the gore non-optimum factors, these reference weights are then compared to flight hardware weights reported in a mass properties database. When manufacturing tolerance weight estimates are taken into account, the gore non-optimum factors computed using the coarse weights model range from 1.28 to 2.76, with an average non-optimum factor of 1.90. Application of the refined weights model yields non-optimum factors between 1.00 and 1.50, with an average non-optimum factor of 1.14. To demonstrate their use, these calculated non-optimum factors are used to predict heavier, more realistic gore weights for a proposed heavy-lift launch vehicle s propellant tank bulkheads. These results indicate that relatively simple models can be developed to better estimate the actual weights of large structures for future launch vehicles.

  20. The Expanding Universe: Dark Energy

    Energy Technology Data Exchange (ETDEWEB)

    Lincoln, Don [Fermilab; Nord, Brian [Fermilab

    2014-09-01

    In 1998, observations of distant supernovae led physicists that not only was the universe expanding, but the expansion was speeding up. In this article, we describe the evidence for an expanding universe and describe what physicists and cosmologists have learned in the intervening years. The target audience for this article is high school physics teachers and college physics professors at teaching institutions.

  1. Screw expander for light duty diesel engines

    Science.gov (United States)

    1983-01-01

    Preliminary selection and sizing of a positive displacement screw compressor-expander subsystem for a light-duty adiabatic diesel engine; development of a mathematical model to describe overall efficiencies for the screw compressor and expander; simulation of operation to establish overall efficiency for a range of design parameters and at given engine operating points; simulation to establish potential net power output at light-duty diesel operating points; analytical determination of mass moments of inertia for the rotors and inertia of the compressor-expander subsystem; and preparation of engineering layout drawings of the compressor and expander are discussed. As a result of this work, it was concluded that the screw compressor and expander designed for light-duty diesel engine applications are viable alternatives to turbo-compound systems, with acceptable efficiencies for both units, and only a moderate effect on the transient response.

  2. Reactivity of Cu with poly(tetrafluoroethylene) and poly(vinyl chloride): Effect of pre- and post-metallization modification on the metal/polymer interface

    International Nuclear Information System (INIS)

    Perry, C.C.; Torres, J.; Carlo, S.R.; Fairbrother, D. Howard

    2002-01-01

    The reactivity of Cu with poly(tetrafluoroethylene) (PTFE) and poly(vinylchloride) (PVC) during thermal evaporation, as well as the effect of pre- and post-metallization Ar + ion and x-ray mediated surface modification treatments on the metal/polymer interface, have been studied using in situ x-ray photoelectron spectroscopy (XPS) and ex situ atomic force microscopy (AFM). During thermal evaporation, copper was unreactive on PTFE but reacted with PVC to form CuCl. Pretreatment of PTFE or PVC surfaces by Ar + ion or x-ray irradiation did not modify the chemical reactivity of the polymer surface during subsequent Cu deposition, although significant morphological changes were observed on PTFE by AFM. In contrast, post-metallization modification of the Cu/PTFE interface by Ar + ion or x-ray irradiation lead to the production of CuF 2 , and increased the yield of CuCl in the Cu/PVC system. In either the Cu/PTFE or Cu/PVC systems, the maximum concentration of copper halide formed and dependence upon treatment time was found to be similar for either Ar + ion or x-ray irradiation post-metallization treatment strategies, suggesting a common reaction mechanism

  3. Study on radiation grafting of acrylic acid onto fluorine-containing polymers. II. Properties of membrane obtained by preirradiation grafting onto poly(tetrafluoroethylene)

    International Nuclear Information System (INIS)

    Hegazy, E.S.A.; Ishigaki, I.; Rabie, A.; Dessouki, A.M.; Okamoto, J.

    1981-01-01

    Some properties of the membranes obtained by the preirradiation grafting of acrylic acid onto poly(tetrafluoroethylene) (PTFE) film have been studied. The dimensional change by grafting and swelling, water uptake, electric conductivity, and mechanical properties of the grafted PTFE films were measured and were found to increase as the grafting proceeds. These properties were found to be dependent mainly on the degree of grafting regardless of grafting conditions except higher monomer concentration (80 wt %). The electric conductivity and mechanical properties of the membranes at 80 wt % monomer concentration is lower than those at a lower monomer concentration. The results suggest that the membranes obtained at 80-wt % acrylic acid solution have a somewhat heterogeneous distribution of electrolyte groups as compared with those prepared at a monomer concentration less than 60 wt %. X-ray microscopy of the grafted films revealed that the grafting begins at the part close to the film surface and proceeds into the center with progressive diffusion of monomer to give finally the homogeneous distribution of electrolyte groups. The membranes show good electrochemical and mechanical properties which make them acceptable for the practical uses as cation exchange membrane

  4. Educator Preparedness to Teach Environmental Science in Secondary Schools

    Science.gov (United States)

    Guillory, Linus Joseph, Jr.

    2012-01-01

    This study assesses the environmental proficiency of Texas life science educators certified from 2003 to 2011 by analyzing their TExES 138 8-12 exam results in domains V and VI. The sample consisted of all the individuals that took and passed the TExES 138 life science 8-12 exam. During this period, approximately 41% of the individuals who took…

  5. A-coupled-expanding and distributional chaos

    International Nuclear Information System (INIS)

    Kim, Cholsan; Ju, Hyonhui; Chen, Minghao; Raith, Peter

    2015-01-01

    The concept of A-coupled-expanding maps is one of the more natural and useful ideas generalized from the horseshoe map which is commonly known as a criterion of chaos. It is well known that distributional chaos is one of the concepts which reflect strong chaotic behavior. In this paper, we focus on the relationship between A-coupled-expanding and distributional chaos. We prove two theorems which give sufficient conditions for a strictly A-coupled-expanding map to be distributionally chaotic in the senses of two kinds, where A is an m × m irreducible transition matrix

  6. Optimization of RNA preservation in granulation tissue in the expanded polytetrafluoroethylene (ePTFE) tube model

    DEFF Research Database (Denmark)

    Danielsen, Patricia L; Koudahl, V; Christensen, B

    2009-01-01

    , removed after ten days and randomized to four RNA preservation groups. Storage in RNAlater at 4 degrees C and snap freezing in methanol/acetone yielded significantly better RNA quality than snap freezing with liquid nitrogen and storage in RNAlater at -80 degrees C. Snap freezing in liquid nitrogen failed...

  7. Stability of expanded plasma focus

    International Nuclear Information System (INIS)

    Soliman, H.M.

    1994-01-01

    In this study, the stabilization of the expanded plasma focus formed by 4.5 kJ plasma focus device of Mather type by magnetic field is presented. The experimental results of the induced axial magnetic field and electric probe measurements of the expanded plasma focus show that, the plasma consists of three plasmoids, electron temperature measurements off the plasmoids at a point close to the muzzle are 26 eV, 30 eV and 27 eV respectively and the electron densities are 6.6 x 10 14 , 6.1 x 10 14 / cm 3 respectively. The presence of external axial magnetic field (B 2 = 1.6 kg) at the mid distance between the breech and the muzzle has a less effect on the stability of expanded focus and it causes a restriction for the plasma motion. the electron temperature of the three plasmoids are found to increase in that case by 23%, 18.5% respectively. When this axial magnetic field is applied at the muzzle end, it leads to a more stable expanded plasma focus which consists mainly of one plasmoid with electron temperature of 39 eV and density of 3.4 x 10 14 / cm 3 . 5 figs

  8. Expanding/Extending English: Interdisciplinarity and Internationalism.

    Science.gov (United States)

    Fleishman, Avrom

    1994-01-01

    Discusses the recent efforts to expand literary studies into numerous allied fields and the possible effects that such attempts toward interdisciplinarity and internationalism might have. Warns against possible negative consequences of interdisciplinary approaches. Calls for an expanded view of English as a field of study. (HB)

  9. Geothermal ORC Systems Using Large Screw Expanders

    OpenAIRE

    Biederman, Tim R.; Brasz, Joost J.

    2014-01-01

    Geothermal ORC Systems using Large Screw Expanders Tim Biederman Cyrq Energy Abstract This paper describes a low-temperature Organic Rankine Cycle Power Recovery system with a screw expander a derivative of developed of Kaishan's line of screw compressors, as its power unit. The screw expander design is a modified version of its existing refrigeration compressor used on water-cooled chillers. Starting the ORC development program with existing refrigeration screw compre...

  10. The effect of Se/Te ratio on transient absorption behavior and nonlinear absorption properties of CuIn0.7Ga0.3(Se1-xTex)2 (0 ≤ x ≤ 1) amorphous semiconductor thin films

    Science.gov (United States)

    Karatay, Ahmet; Küçüköz, Betül; Çankaya, Güven; Ates, Aytunc; Elmali, Ayhan

    2017-11-01

    The characterization of the CuInSe2 (CIS), CuInGaSe (CIGS) and CuGaSe2 (CGS) based semiconductor thin films are very important role for solar cell and various nonlinear optical applications. In this paper, the amorphous CuIn0.7Ga0.3(Se1-xTex)2 semiconductor thin films (0 ≤ x ≤ 1) were prepared with 60 nm thicknesses by using vacuum evaporation technique. The nonlinear absorption properties and ultrafast transient characteristics were investigated by using open aperture Z-scan and ultrafast pump-probe techniques. The energy bandgap values were calculated by using linear absorption spectra. The bandgap values are found to be varying from 0.67 eV to 1.25 eV for CuIn0.7Ga0.3Te2, CuIn0.7Ga0.3Se1.6Te0.4, CuIn0.7Ga0.3Se0.4Te1.6 and CuIn0.7Ga0.3Se2 thin films. The energy bandgap values decrease with increasing telluride (Te) doping ratio in mixed CuIn0.7Ga0.3(Se1-xTex)2 films. This affects nonlinear characteristics and ultrafast dynamics of amorphous thin films. Ultrafast pump-probe experiments indicated that decreasing of bandgap values with increasing the Te amount switches from the excited state absorption signals to ultrafast bleaching signals. Open aperture Z-scan experiments show that nonlinear absorption properties enhance with decreasing bandgaps values for 65 ps pulse duration at 1064 nm. Highest nonlinear absorption coefficient was found for CuIn0.7Ga0.3Te2 thin film due to having the smallest energy bandgap.

  11. Factors leading to tracheobronchial self-expandable metallic stent fracture.

    Science.gov (United States)

    Chung, Fu-Tsai; Lin, Shu-Min; Chen, Hao-Cheng; Chou, Chun-Liang; Yu, Chih-Teng; Liu, Chien-Ying; Wang, Chun-Hua; Lin, Horng-Chyuan; Huang, Chien-Da; Kuo, Han-Pin

    2008-11-01

    This retrospective study was to determine factors that contribute to self-expandable metallic stent fracture in patients with tracheobronchial disease. From 2001 to 2006, 139 patients (age, 62.1 +/- 15.4 years; range, 23-87 years) with benign (n = 62) and malignant (n = 77) tracheobronchial disease received 192 Ultraflex (Boston Scientific, Natick, Mass) self-expandable metallic stents (98 in patients with benign disease and 94 in patients with malignant disease). Seventeen fractured self-expandable metallic stents were found; the incidence was 12.2% (17/139 patients) among patients with tracheobronchial disease. Tortuous airway (odds ratio, 4.06; 95% confidence interval, 1.04-18.34; P = .04) independently predicted self-expandable metallic stent fracture. Most self-expandable metallic stent fractures (64.7%, 11/17) were detected 500 to 1000 days after self-expandable metallic stent implantation. Clinical presentations for patients with fractured self-expandable metallic stents included dyspnea exacerbation (70.6%, 12/17) and cough (23.5%, 4/17). Self-expandable metallic stent fracture is not uncommon in patients with tracheobronchial disease. Tortuous airway is an independent predictor for it. Although management of the fractured self-expandable metallic stent in our study was feasible and safe, self-expandable metallic stents should be restricted to a more select population.

  12. Neutrinos in an expanding Universe

    International Nuclear Information System (INIS)

    Wigmans, Richard

    2015-01-01

    The Universe contains several billion neutrinos for each nucleon. In this paper, we follow the history of these relic neutrinos as the Universe expanded. At present, their typical velocity is a few hundred km/s and, therefore, their spectra are affected by gravitational forces. This may have led to a phenomenon that could explain two of todays great mysteries: The large-scale structure of the Universe and the increasing rate at which it expands. (paper)

  13. Rule-based expert system to establish the linkage between yarn twist factor and end-use.

    CSIR Research Space (South Africa)

    Dlodlo, N

    2009-09-01

    Full Text Available of the fibre alignment to axis. The tex twist factor αtex is defined as: where: αtex is the tex twist factor, t = twist expressed in turns/metre (or turns/centimetre), Ti = the effective linear density (count) of the composite yarn expressed in tex... of staple fibre yarns. They can be classed by fibre length (e.g. short and long staple), by spinning system (e.g. ring and rotor), or by yarn construction (e.g. single, plied, cabled, multiple and fancy). Ring-spun yarns are produced on 1000/itex Tt=α m...

  14. Free-piston reciprocating cryogenic expander utilizing phase controller

    Science.gov (United States)

    Cha, Jeongmin; Park, Jiho; Kim, Kyungjoong; Jeong, Sangkwon

    2017-02-01

    In a free-piston expander which eliminates mechanical linkages, a prescribed behaviour of the free-piston movement is the key to an expander performance. In this paper, we have proposed an idea of reducing complexity of the free-piston expander. It is to replace both multiple solenoid valves and reservoirs that are indispensable in a previous machine with a combination of a single orifice-reservoir assembly. It functions as a phase controller like that of a pulse tube refrigerator so that it generates time-delay of pressure variation between the warm-end and the reservoir resulting in the intended expansion of the cold-end volume down to the pre-set reservoir pressure. The modeling of this unique free-piston reciprocating expander utilizing phase controller is developed to understand and predict the performance of the new-type expander. Additionally, the operating parameters are analysed at the specified conditions to enable one to develop a more efficient free-piston type cryogenic expander.

  15. New generation expandable sand screens

    OpenAIRE

    Syltøy, Christer

    2014-01-01

    Master's thesis in Petroleum engineering This thesis aims to give a general insight into sand control and various sorts of sand control measures and applications of sand control tools. Special focus will be given to expandable sand screens – a technology which came about in the late 1990’s through the use of flexible, expandable tubulars as base pipe in sand screens. More specifically Darcy’s Hydraulic Endurance Screens, a compliant sand screen system using hydraulic activation, and the fu...

  16. Synergism of carbon fiber and polyimide in polytetrafluoroethylene-based composites: Friction and wear behavior under sea water lubrication

    International Nuclear Information System (INIS)

    Chen, Beibei; Wang, Jianzhang; Yan, Fengyuan

    2012-01-01

    Highlights: ► The effect of PI and CF on the microstructure of PTFE was investigated. ► PI and CF had synergism on the improvement of tribological property of PTFE. ► PTFE-4 (with 5% PI and 15% CF) showed promising application in ocean environment. -- Abstract: Polytetrafluoroethylene-based (PTFE-based) composites reinforced simultaneously with carbon fiber (CF) and polyimide (PI) of different volume fractions were prepared. The microstructure and phase composition of as-prepared PTFE-based composites were analyzed by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). Besides, their friction and wear behavior under sea water lubrication was evaluated in relation to the synergistic effect between CF and PI using a ring-on-block test rig, and their worn surfaces were also analyzed using SEM. Results showed that the incorporation of PI induced loosening of the microstructure of PTFE but increased the wear resistance. Contrary to the above, the incorporation of CF led to increased compactness of PTFE, and the compactness as well as wear resistance of the PTFE-based composites increased with the increase of CF content. More importantly, the simultaneous incorporation of PI and CF at a proper volume fraction led to drastically reduced wear rate of PTFE under sea water lubrication. This implies that there exists synergistic friction-reducing and wear-resistant effect between PI and CF. As a result, the PTFE-based composite containing 5% PI (volume fraction) and 15% CF had the best wear resistance, showing promising application in ocean environment.

  17. Correção endovascular de aneurisma da artéria esplénica: caso clínico Endovascular correction of splenic artery aneurysm: case report

    Directory of Open Access Journals (Sweden)

    José Almeida Lopes

    2012-06-01

    Full Text Available Os aneurismas da artéria esplénica, embora sejam os aneurismas esplâncnicos mais frequentes, cursam com uma prevalência de apenas 0,01%. Neste contexto os autores apresentam um caso clínico de uma doente de 41 anos com aneurisma da artéria esplénica de 20x29mm, tratada através da colocação de um stent coberto auto-expansível (Gore®, Viabahn®. É realizada uma revisão da literatura, das possíveis complicações e feita referência às várias hipóteses de tratamento, dando particular ênfase às novas técnicas endovasculares.Splenic artery aneurysms, although they are the most common splanchnic aneurysms, they have a prevalence of only 0,01%. In this context the authors present a case report of a 41 years female patient with a splenic artery aneurysm of 20x29mm, treated by deployment of a covered self-expandable stent (Gore® Viabahn®. It is performed a literature review of the pathology in question, possible complications and made reference to the various treatment options, with particular emphasis on the new endovascular techniques.

  18. Comparison of a New Polytetrafluoroethylene-Covered Metallic Stent to a Noncovered Stent in Canine Ureters

    International Nuclear Information System (INIS)

    Chung, Hwan-Hoon; Lee, Seung Hwa; Cho, Sung Bum; Park, Hong Suk; Kim, Young Sik; Kang, Byung Chul; Frisoli, Joan K.; Razavi, Mahmood K.

    2008-01-01

    The aim of this study was to determine the feasibility of using a newly designed polytetrafluoroethylene (PTFE)-covered metallic stent in the ureter by comparing its effectiveness with that of the noncovered stent in a canine model. We placed 14 stents in the ureters of seven mongrel dogs that weighed 30-40 kg each. The covered and noncovered stents were deployed in the right and left ureters, respectively, of six dogs. In the seventh dog, a covered stent and a double-J catheter were inserted in the right ureter, and a covered stent only was inserted in the left ureter. The first six dogs were sacrificed at 5, 10, and 15 weeks after deployment of the stents (two for each follow-up period), and the seventh dog was sacrificed at 30 weeks. There was no migration or poor expansion of any of the stents observed on plain radiography. On intravenous pyelogram and retrograde pyelogram, all of the covered stents at each follow-up period had patent lumens at the stented segments without hydronephrosis, and the passage of contrast material through it was well preserved. The noncovered stents in the dogs sacrificed at 5 and 10 weeks and one of the two dogs sacrificed at 15 weeks showed near-complete occlusion of the stent lumen due to ingrowth of the soft tissue, and severe hydronephrosis was also noted. The noncovered stent in the other dog sacrificed at 15 weeks showed the passage of contrast material without hydronephrosis, but the lumen of the stent was still nearly occluded by the soft tissue. There was no evidence of hydronephrosis or passage disturbance of the contrast material in both ureters of the dog sacrificed at 30 weeks. We conclude that the newly designed PTFE-covered stent effectively prevented the luminal occlusion caused by urothelial hyperplasia compared to the near-total occlusion of the noncovered stents, and no migration of the covered stents was noted

  19. Partition expanders

    Czech Academy of Sciences Publication Activity Database

    Gavinsky, Dmitry; Pudlák, Pavel

    2017-01-01

    Roč. 60, č. 3 (2017), s. 378-395 ISSN 1432-4350 R&D Projects: GA ČR GBP202/12/G061 Institutional support: RVO:67985840 Keywords : expanders * pseudorandomness * communication complexity Subject RIV: BA - General Mathematics OBOR OECD: Computer sciences, information science, bioinformathics (hardware development to be 2.2, social aspect to be 5.8) Impact factor: 0.645, year: 2016 http://link.springer.com/article/10.1007%2Fs00224-016-9738-5

  20. The TEX-I real-time expert system applied to situation assessment for the SNR-300 reactor

    International Nuclear Information System (INIS)

    Schmal, N.; Doerbecker, K.; Leder, H.J.; Rueckert, M.; Schade, H.J.

    1990-01-01

    Within the German TEX-I Project, which was sponsored by the Federal Ministry for Research and Technology, several companies developed industrial applications of technical expert systems for data interpretation, diagnosis and process control. The purpose of the diagnosis expert system reported here is to support the operators of the LMFBR SNR-300 in assessing plant status in real-time, based on readings from a large number of sensors. By online connection to the process control computer, it can monitor all incoming signal values, check the consistency of data, continuously diagnose the current plant status, detect unusual trends prior to accidents, localize faulty components and recommend operators response in abnormal conditions. The systems architecture consists of two basic subsystems, an inference engine and an intelligent process interface, implemented in Lisp on a Symbolics-Workstation. The inference engine has been derived from BABYLON, a hybrid shell developed by the German computer research institute GMD. This shell includes rules, prologue, constraints and an object oriented frame processor. The extended version has a component description language and a top-down diagnosis scheme including a mechanism of attention focusing. Inference run as independent, quasi-parallel processes. These so-called inference tasks can interrupt or abort each other, if higher priority events must be processed. The complete system is modelled in an object oriented matter and is divided into several subsystems and each subsystem into its physical components. At present the expert system is connected to a real-time simulation of the reactor. The simulation is based on a thermohydraulic code for simulation of the transient behaviour of temperatures and flow rates in the reactor core, plena, pipes, pumps, valves, intermediate heat exchangers and cooling components. Additionally, the systems response to an asynchronous operator interaction can be simulated. Several types of anomalies

  1. Flow boiling in expanding microchannels

    CERN Document Server

    Alam, Tamanna

    2017-01-01

    This Brief presents an up to date summary of details of the flow boiling heat transfer, pressure drop and instability characteristics; two phase flow patterns of expanding microchannels. Results obtained from the different expanding microscale geometries are presented for comparison and addition to that, comparison with literatures is also performed. Finally, parametric studies are performed and presented in the brief. The findings from this study could help in understanding the complex microscale flow boiling behavior and aid in the design and implementation of reliable compact heat sinks for practical applications.

  2. Aortic annulus eccentricity before and after transcatheter aortic valve implantation: Comparison of balloon-expandable and self-expanding prostheses

    International Nuclear Information System (INIS)

    Schuhbaeck, Annika; Weingartner, Christina; Arnold, Martin; Schmid, Jasmin; Pflederer, Tobias; Marwan, Mohamed; Rixe, Johannes; Nef, Holger; Schneider, Christian; Lell, Michael; Uder, Michael; Ensminger, Stephan; Feyrer, Richard; Weyand, Michael; Achenbach, Stephan

    2015-01-01

    Highlights: • Post-implant geometry of catheter-based aortic valve prostheses is influenced by aortic valve calcification. • Balloon-expandable prostheses are more circular as compared to self-expanding prostheses. • The impact of post-implant geometry on valve function needs to be investigated. - Abstract: Introduction: The geometry of the aortic annulus and implanted transcatheter aortic valve prosthesis might influence valve function. We investigated the influence of valve type and aortic valve calcification on post-implant geometry of catheter-based aortic valve prostheses. Methods: Eighty consecutive patients with severe aortic valve stenosis (mean age 82 ± 6 years) underwent computed tomography before and after TAVI. Aortic annulus diameters were determined. Influence of prosthesis type and degree of aortic valve calcification on post-implant eccentricity were analysed. Results: Aortic annulus eccentricity was reduced in patients after TAVI (0.21 ± 0.06 vs. 0.08 ± 0.06, p < 0.0001). Post-TAVI eccentricity was significantly lower in 65 patients following implantation of a balloon-expandable prosthesis as compared to 15 patients who received a self-expanding prosthesis (0.06 ± 0.05 vs. 0.15 ± 0.07, p < 0.0001), even though the extent of aortic valve calcification was not different. After TAVI, patients with a higher calcium amount retained a significantly higher eccentricity compared to patients with lower amounts of calcium. Conclusions: Patients undergoing TAVI with a balloon-expandable prosthesis show a more circular shape of the implanted prosthesis as compared to patients with a self-expanding prosthesis. Eccentricity of the deployed prosthesis is affected by the extent of aortic valve calcification

  3. Latex allergy: an emerging

    Directory of Open Access Journals (Sweden)

    Fernando Samuel Sion

    2013-11-01

    Full Text Available RESUMO: A alergia ao látex é manifestação de hipersensibilidade imediata mediada por IgE à proteína do látex natural, com variedade de sinais clínicos como urticária de contato, dermatite de contato por irritação primária ou por mecanismo de hipersensibilidade tardia, angioedema, asma, até anafilaxia. Com maior risco para a alergia ao látex estão os trabalhadores da área de saúde e demais profissões que usam látex. Pacientes com hipersensibilidade ao látex podem apresentar reação cruzada a frutas / alimentos, especialmente banana, kiwi e abacate. O diagnóstico é feito por detecção de anticorpos IgE específicos, testes cutâneos de puntura e testes de contato. Prevenção à exposição, substituição e utilização de produtos livres de látex, como luvas sintéticas são essenciais para os afetados. Adaptações no local de trabalho devem ser feitas com uso de luvas sem talco, com baixo teor de alérgenos ou luvas sintéticas. Estas medidas preventivas reduziram significativamente a prevalência de reações. Descritores: Alergia ao látex, Alimentos e alergia ao látex, Prevenção a reação ao látex.

  4. Actividad Ribonucleasa en el Látex de Calotropis procera (Aiton W.T. Aiton y Pedilanthus tithymaloides (L. Poit / Ribonuclease Activity in Latex from Calotropis procera (Aiton W.T. Aiton and Pedilanthus tithymaloides (L. Poit

    Directory of Open Access Journals (Sweden)

    Emma Rueda de Arvelo

    2013-12-01

    Full Text Available Las enzimas ribonucleasas (RNasas han sido utilizadascon efectividad en el tratamiento de ciertos tipos de cáncer ypueden tener otras propiedades aplicables en biotecnología. Con el objetivo de identificar la presencia de actividad RNasa en el látex de las plantas tropicales Calotropis procera y Pedilanthus tithymaloides se colectaron muestras a partir de plantas adultas ubicadas al norte del estado Aragua, Venezuela. Las proteínas solubles fueron extraídas con acetato de sodio 50 mM pH 5 (16 μL/μgde látex y eliminada la porción poliisoprenoide por centrifugación a 16.000 x g durante 15 min. La actividad RNasa se estimó utilizando una técnica que incluye la aplicación de alícuotas de la mezcla de reacción sobre geles de poliacrilamida-urea y separadaspor electroforesis. La degradación del sustrato fue cuantificada pordensitometría. Se probaron diversos sustratos (ARNttotal, ARNtphe yARNm transcrito in vitro a partir de ADN plasmídico. El látexde ambas especies presentó actividad RNasa, con actividadesespecíficas iniciales de 1,42 ± 0,74 μg de ARN hidrolizado/min/ μg de proteína; 0,45 ± 0,18 ng de ARN hidrolizado/min/ng de proteína y 0,28 ± 0,07 ng de ARN hidrolizado/min/ng de proteínapara el ARNttotal, ARNm transcrito y ARNtphe, respectivamente, en C. procera, y de 0,02 ± 0,001 ng de ARN hidrolizado/min/ng de proteína para el ARNm transcrito y ARNtphe en P. tithymaloides. Este constituye el primer reporte acerca de la presencia de enzimas RNasas en el látex de estas especies. / Ribonuclease enzymes (RNase have been used effectively in the treatment of certain cancers and other properties that may be applicable in biotechnology. In order to identify the RNase activity in the latex of Calotropis procera and Pedilanthus tithymaloides, tropical plants samples were collected from adult plants located in the North State of Aragua, Venezuela. Soluble proteins were extracted with 50 mM sodium acetate pH 5 (16

  5. Time-dependent strains and stresses in a pumpkin balloon

    Science.gov (United States)

    Gerngross, T.; Xu, Y.; Pellegrino, S.

    This paper presents a study of pumpkin-shaped superpressure balloons consisting of gores made from a thin polymeric film attached to high stiffness meridional tendons This type of design is being used for the NASA ULDB balloons The gore film shows considerable time-dependent stress relaxation whereas the behaviour of the tendons is essentially time-independent Upon inflation and pressurization the instantaneous i e linear-elastic strain and stress distributions in the film show significantly higher values in the meridional direction However over time and due to the biaxial visco-elastic stress relaxation of the the gore material the em hoop strains increase and the em meridional stresses decrease whereas the em remaining strain and stress components remain substantially unchanged These results are important for a correct assessment of the structural integrity of a pumpkin balloon in a long-duration mission both in terms of the material performance and the overall stability of the shape of the balloon An experimental investigation of the time dependence of the biaxial strain distribution in the film of a 4 m diameter 48 gore pumpkin balloon is presented The inflated shape of selected gores has been measured using photogrammetry and the time variation in strain components at some particular points of these gores has been measured under constant pressure and temperature The results show good correlation with a numerical study using the ABAQUS finite-element package that includes a widely used model of

  6. Entropy in an expanding universe

    International Nuclear Information System (INIS)

    Frautschi, S.

    1982-01-01

    The question of how the observed evolution of organized structures from initial chaos in the expanding universe can be reconciled with the laws of statistical mechanics is studied, with emphasis on effects of the expansion and gravity. Some major sources of entropy increase are listed. An expanding causal region is defined in which the entropy, though increasing, tends to fall further and further behind its maximum possible value, thus allowing for the development of order. The related questions of whether entropy will continue increasing without limit in the future, and whether such increase in the form of Hawking radiation or radiation from positronium might enable life to maintain itself permanently, are considered. Attempts to find a scheme for preserving life based on solid structures fail because events such as quantum tunneling recurrently disorganize matter on a very long but fixed time scale, whereas all energy sources slow down progressively in an expanding universe. However, there remains hope that other modes of life capable of maintaining themselves permanently can be found

  7. Ex-vivo release of Pipeline Embolization Device polytetrafluoroethylene (PTFE) sleeves for improved distal landing zone accuracy in-vivo: A technical note.

    Science.gov (United States)

    Griessenauer, Christoph J; Gupta, Raghav; Moore, Justin; Thomas, Ajith J; Ogilvy, Christopher S

    2016-12-01

    Distal landing zone accuracy is critical in some intracranial aneurysms treated with the Pipeline Embolization Device (PED), and delayed opening of the distal end of the device can complicate the procedure. Here, we report a technical nuance that facilitates accurate placement of the distal end of the PED by ex-vivo, pre-implantation release of the PED Flex polytetrafluoroethylene (PTFE) sleeves. The PED Flex is partially pushed out of the introducer sheath ex-vivo, pre-implantation until the distal PED opens entirely and the PTFE sleeves are located distal to the device. Without inverting the PTFE sleeves, the PED is carefully pulled back into the introducer sheath placing the PTFE sleeves inside the device. The PED is loaded into the microcatheter and advanced toward the site of implantation. When the PED is initially deployed and pushed out of the microcatheter, it opens immediately and provides an anchor for the remainder of the deployment process. We present a video (supplementary material) that illustrates the technique along with an illustrative case. Ex-vivo, pre-implantation release of the PTFE sleeves is an option in aneurysm treatment where distal landing accuracy is critical. Even without the protection of the PTFE sleeves, our clinical observation shows that the PED can be advanced safely through the microcatheter in selected cases. © The Author(s) 2016.

  8. Solid expandable systems put deepwater targets within reach

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Roca, Eduardo [Enventure Global Technology L.L.C., Houston, TX (United States). Latin America; Fristch, Jerry [Enventure Global Technology L.L.C., Houston, TX (United States)

    2008-07-01

    Enabling technologies that take drilling operations to deeper objectives have made a significant impact on the practicality of many projects, especially deep water offshore targets. Increasing vertical depth and lateral reach requires adequate hole size to attain the desired objectives of the well bore. Solid expandable technology can maintain and retain hole size to address both the physical limitations and the economic feasibility of deep water operations. With each and every casing point, the potential for adequate hole size at total depth (TD) decreases. Solid expandable open hole liners and single-diameter systems reduce and eliminate, respectively, the well bore tapering that dictates hole size at TD and subsequent completion size. Successful mitigation of this tapering, whether through the entire well bore or through select zones, enables operators to gain access to previously unreachable reserves. Solid expandable systems have proven to be reliable and effective with over 1,000 installations in a myriad of conditions and environments worldwide. To date, over 115 of those applications have been in deep water environments. The current operating envelope for solid expandable systems include the deepest installation at {approx}28,750 ft (8,763 m) and the longest at 6,867 ft (2,083 m) in water depth over 3,150 ft (960 m). This record-length application consisted of an open hole liner installed and expanded in a single run. This paper will discuss the effectiveness of solid expandable systems in deep water operations and how the technology brings value to offshore projects especially when planned into the initial design. Case histories will be used to further illustrate the features, advantages, and benefits of expandable technology. In addition, this paper will examine the state of the solid expandable technology and its continuing evolution to provide even more drilling solutions. (author)

  9. Histological evaluation of different biodegradable and non-biodegradable membranes implanted subcutaneously in rats

    DEFF Research Database (Denmark)

    Zhao, S; Pinholt, E M; Madsen, J E

    2000-01-01

    Different types of biodegradable membranes have become available for guided tissue regeneration. The purpose of this study was to evaluate histologically three different biodegradable membranes (Bio-Gide, Resolut and Vicryl) and one non-biodegradable membrane (expanded polytetrafluoroethylene/e-PTFE...... that e-PTFE was well tolerated and encapsulated by a fibrous connective tissue capsule. There was capsule formation around Resolut and Vicryl and around Bio-Gide in the early phase there was a wide inflammatory zone already. e-PTFE and Vicryl were stable materials while Resolut and Bio-Gide fragmented...

  10. Cell biological characterization of the malaria vaccine candidate trophozoite exported protein 1.

    Directory of Open Access Journals (Sweden)

    Caroline Kulangara

    Full Text Available In a genome-wide screen for alpha-helical coiled coil motifs aiming at structurally defined vaccine candidates we identified PFF0165c. This protein is exported in the trophozoite stage and was named accordingly Trophozoite exported protein 1 (Tex1. In an extensive preclinical evaluation of its coiled coil peptides Tex1 was identified as promising novel malaria vaccine candidate providing the rational for a comprehensive cell biological characterization of Tex1. Antibodies generated against an intrinsically unstructured N-terminal region of Tex1 and against a coiled coil domain were used to investigate cytological localization, solubility and expression profile. Co-localization experiments revealed that Tex1 is exported across the parasitophorous vacuole membrane and located to Maurer's clefts. Change in location is accompanied by a change in solubility: from a soluble state within the parasite to a membrane-associated state after export to Maurer's clefts. No classical export motifs such as PEXEL, signal sequence/anchor or transmembrane domain was identified for Tex1.

  11. Superhydrophobic coatings fabricated with polytetrafluoroethylene and SiO2 nanoparticles by spraying process on carbon steel surfaces

    International Nuclear Information System (INIS)

    Wang, Haibin; Chen, Eryu; Jia, Xianbu; Liang, Lijun; Wang, Qi

    2015-01-01

    Graphical abstract: - Highlights: • The SiO 2 and PTFE NP-filled coatings exhibit excellent superhydrophobicity. • PTFE-filled coatings show denser structures and better liquid resistance than SiO 2 . • Air pocket of Wentzel model explains the difference in the superhydrophobicity. - Abstract: Superhydrophobicity is extensively investigated because of the numerous methods developed for water-repellant interface fabrication. Many suitable functional materials for the production of superhydrophobic surfaces on various substrates are still being explored. In this study, inorganic SiO 2 and organic polytetrafluoroethylene (PTFE) nanoparticles (NPs) are used for a comparative study on the performance of superhydrophobic coating on carbon steel surfaces. The NPs are added to PTFE coating emulsions by physical blending to form coating mixtures. Raw SiO 2 NPs are then hydrophobized using KH-570 and validated by Fourier transform-infrared spectroscopy (FT-IR) and Dynamic Laser Scattering (DLS) grain size analyses. The microstructures of the surfaces are characterized by contact angle (CA) measurements and field emission-scanning electron microscope (FE-SEM) images. The prepared surfaces are subjected to adhesion, hardness, water resistance, and acid/alkali erosion tests. Hydrophobized SiO 2 -filled coating surfaces are found to have better uniformity than raw SiO 2 regardless of their similar maximum static contact angles (SCAs) about 150°. A SCA of 163.1° is obtained on the PTFE NP-filled coating surfaces that have a considerably denser structure than SiO 2 . Thermogravimetric (TG) and differential scanning calorimetry (DSC) analyses reveal that all fabricated surfaces have good thermal stability and tolerate temperatures up to 550 °C. The PTFE NP-filled coating surfaces also exhibit excellent water and acid resistance. A possible mechanism concerning the amount of trapped air is proposed in relation to practical superhydrophobic surface fabrication

  12. We must speak of hope as well as catastrophe.

    Science.gov (United States)

    Rafferty, Anne Marie

    2017-08-23

    Al Gore, the former US vice-president and now campaigner on climate change, has just released a follow-up to his groundbreaking 2006 documentary An Inconvenient Truth. Gore's first film won an Oscar and grossed $49 million - astonishing for a documentary.

  13. Estimulación de la actividad péptica del jugo gástrico, inducida por látex de Croton palanostigma (sangre de grado

    Directory of Open Access Journals (Sweden)

    Miguel Sanvodal

    2008-09-01

    Full Text Available Objetivo: Determinar si la administración del látex de Croton palanostigma (sangre de grado, vía digestiva, modifica la actividad péptica de la secreción gástrica. Diseño: Estudio experimental. Institución: Centro de Investigación de Bioquímica y Nutrición Alberto Guzmán Barrón, Facultad de Medicina, Universidad Nacional Mayor de San Marcos. Material biológico: Ratas albinas machos adultos y sangre de grado. Métodos: Se usó 50 ratas albinas machos adultos, entre 200 y 250 g de peso, que fueron distribuidas aleatoriamente en 5 grupos, a los que se administró por vía oro-gástrica, y en dosis única, como sigue: grupo I: 0,8 mL/kg de sangre de grado; grupo II: 0,8 mL/kg de sangre de grado neutralizada; grupo III: ranitidina 50 mg/kg; grupo IV: control, con solución salina 0,9 g% (sin histamina; grupo V: control con solución salina 0,9 g%. Se realizó ligadura pilórica, por laparotomía, con anestesia de éter etílico. Se utilizó histamina, aplicada por vía subcutánea, para estimular la secreción, excepto al grupo IV. Cuatro horas después, se extrajo el jugo gástrico, se midió el volumen, el pH por potenciometría y la actividad de la pepsina, por el método de Anson modificado, expresado como µg de tirosina/mL. Principales medidas de resultados: Modificación de la actividad péptica de la secreción gástrica. Resultados: El volumen del jugo gástrico fue significativamente menor en los grupos II y III; que en los otros, entre los que no hubo diferencia estadística. El pH del grupo III (con ranitidina fue significativamente mayor que los otros, demostrando el efecto del fármaco. La actividad péptica fue: con sangre de grado 5,34+1,04; sangre de grado neutralizada 2,69+1,27; grupo ranitidina 2,57+0,88; el control sin histamina 3,29+0,94 y control con histamina 3,58+1,18. La actividad péptica fue significativamente mayor (+49,2% en el grupo con sangre de grado (p<0,01 que en los otros grupos. Conclusiones

  14. Conceptual design of initial opacity experiments on the national ignition facility

    Energy Technology Data Exchange (ETDEWEB)

    Heeter, R.  F.; Bailey, J.  E.; Craxton, R.  S.; DeVolder, B.  G.; Dodd, E.  S.; Garcia, E.  M.; Huffman, E.  J.; Iglesias, C.  A.; King, J.  A.; Kline, J.  L.; Liedahl, D.  A.; McKenty, P.  W.; Opachich, Y.  P.; Rochau, G.  A.; Ross, P.  W.; Schneider, M.  B.; Sherrill, M.  E.; Wilson, B.  G.; Zhang, R.; Perry, T.  S.

    2017-01-09

    Accurate models of X-ray absorption and re-emission in partly stripped ions are necessary to calculate the structure of stars, the performance of hohlraums for inertial confinement fusion and many other systems in high-energy-density plasma physics. Despite theoretical progress, a persistent discrepancy exists with recent experiments at the Sandia Z facility studying iron in conditions characteristic of the solar radiative–convective transition region. The increased iron opacity measured at Z could help resolve a longstanding issue with the standard solar model, but requires a radical departure for opacity theory. To replicate the Z measurements, an opacity experiment has been designed for the National Facility (NIF). The design uses established techniques scaled to NIF. A laser-heated hohlraum will produce X-ray-heated uniform iron plasmas in local thermodynamic equilibrium (LTE) at temperatures<tex-math>${\\geqslant}150$tex-math> eV and electron densities<tex-math>${\\geqslant}7\\times 10^{21}~\\text{cm}^{-3}$tex-math>. The iron will be probed using continuum X-rays emitted in a<tex-math>${\\sim}200$tex-math> ps,<tex-math>${\\sim}200~\\unicode[STIX]{x03BC}\\text{m}$tex-math>diameter source from a 2 mm diameter polystyrene (CH) capsule implosion. In this design

  15. Novel power MOSFET-based expander for high frequency ultrasound systems.

    Science.gov (United States)

    Choi, Hojong; Shung, K Kirk

    2014-01-01

    The function of an expander is to obstruct the noise signal transmitted by the pulser so that it does not pass into the transducer or receive electronics, where it can produce undesirable ring-down in an ultrasound imaging application. The most common type is a diode-based expander, which is essentially a simple diode-pair, is widely used in pulse-echo measurements and imaging applications because of its simple architecture. However, diode-based expanders may degrade the performance of ultrasonic transducers and electronic components on the receiving and transmitting sides of the ultrasound systems, respectively. Since they are non-linear devices, they cause excessive signal attenuation and noise at higher frequencies and voltages. In this paper, a new type of expander that utilizes power MOSFET components, which we call a power MOSFET-based expander, is introduced and evaluated for use in high frequency ultrasound imaging systems. The performance of a power MOSFET-based expander was evaluated relative to a diode-based expander by comparing the noise figure (NF), insertion loss (IL), total harmonic distortion (THD), response time (RT), electrical impedance (EI) and dynamic power consumption (DPC). The results showed that the power MOSFET-based expander provided better NF (0.76 dB), IL (-0.3 dB) and THD (-62.9 dB), and faster RT (82 ns) than did the diode-based expander (NF (2.6 dB), IL (-1.4 dB), THD (-56.0 dB) and RT (119 ns)) at 70 MHz. The -6 dB bandwidth and the peak-to-peak voltage of the echo signal received by the transducer using the power MOSFET-based expander improved by 17.4% and 240% compared to the diode-based expander, respectively. The new power MOSFET-based expander was shown to yield lower NF, IL and THD, faster RT and lower ring down than the diode-based expander at the expense of higher dynamic power consumption. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Origin and dynamics of expanding neutral hydrogen supershells

    International Nuclear Information System (INIS)

    Kolesnik, I.G.; Silich, S.A.

    1987-01-01

    The evolutionary model of expanding supershells regulated by induced star formation is proposed. It is suggested that giant expanding shells are formed n superclouds at late evolutionary stage of star complexes. To understand the dynamics of the most huge supershells it is necessary to take into account that expanding shells can trigger star formation in cold dense pre-exosting cloudlets. Efficiency of induced star formation must be less than one percent to fit observational properties of supershells

  17. Seal-less cryogenic expander

    International Nuclear Information System (INIS)

    Faria, L.E.; Christopher, E.H.

    1987-01-01

    In an expander for use in a split Stirling cycle refrigeration system of the type wherein a displacer moves with reciprocating motion inside an expander housing, and wherein a plunger force and a regenerator force are formed on the displacer, the plunger force cyclically varying and having a time of minimum and maximum plunger force amplitude, and the regenerator force cyclically varying and having a time of minimum and maximum regenerator force amplitude, the improvement is described comprising: (a) means for maintaining displacer forces, such that the maximum plunger force amplitude is substantially equal to the maximum regenerator force amplitude; and (b) means for adjusting a time difference, the time difference being the time between the time of maximum plunger force and the time of maximum regenerator force such that a measure of the cooling power of the refrigeration system is maximized

  18. Semiclassical expanding discrete space-times

    International Nuclear Information System (INIS)

    Cobb, W.K.; Smalley, L.L.

    1981-01-01

    Given the close ties between general relativity and geometry one might reasonably expect that quantum effects associated with gravitation might also be tied to the geometry of space-time, namely, to some sort of discreteness in space-time itself. In particular it is supposed that space-time consists of a discrete lattice of points rather than the usual continuum. Since astronomical evidence seems to suggest that the universe is expanding, the lattice must also expand. Some of the implications of such a model are that the proton should presently be stable, and the universe should be closed although the mechanism for closure is quantum mechanical. (author)

  19. Refrigeration generation using expander-generator units

    Science.gov (United States)

    Klimenko, A. V.; Agababov, V. S.; Koryagin, A. V.; Baidakova, Yu. O.

    2016-05-01

    The problems of using the expander-generator unit (EGU) to generate refrigeration, along with electricity were considered. It is shown that, on the level of the temperatures of refrigeration flows using the EGU, one can provide the refrigeration supply of the different consumers: ventilation and air conditioning plants and industrial refrigerators and freezers. The analysis of influence of process parameters on the cooling power of the EGU, which depends on the parameters of the gas expansion process in the expander and temperatures of cooled environment, was carried out. The schematic diagram of refrigeration generation plant based on EGU is presented. The features and advantages of EGU to generate refrigeration compared with thermotransformer of steam compressive and absorption types were shown, namely: there is no need to use the energy generated by burning fuel to operate the EGU; beneficial use of the heat delivered to gas from the flow being cooled in equipment operating on gas; energy production along with refrigeration generation, which makes it possible to create, using EGU, the trigeneration plants without using the energy power equipment. It is shown that the level of the temperatures of refrigeration flows, which can be obtained by using the EGU on existing technological decompression stations of the transported gas, allows providing the refrigeration supply of various consumers. The information that the refrigeration capacity of an expander-generator unit not only depends on the parameters of the process of expansion of gas flowing in the expander (flow rate, temperatures and pressures at the inlet and outlet) but it is also determined by the temperature needed for a consumer and the initial temperature of the flow of the refrigeration-carrier being cooled. The conclusion was made that the expander-generator units can be used to create trigeneration plants both at major power plants and at small energy.

  20. Rukopisi ne goreli, ne goreli, a potom nakonets zanjalis / Jelena Skulskaja

    Index Scriptorium Estoniae

    Skulskaja, Jelena, 1950-

    2002-01-01

    Roman Viktjuki teatri külalisetendused Eestis : fragmentaarium Mihhail Bulgakovi romaani "Meister ja Margarita" järgi ehk "Ivan Bezdomnõi unenäod" 5. ja 6. veebruaril Tallinna Vene Kultuurikeskuses

  1. EXPANDED POLYTETRAFLUOROETHYLENE PATCH VERSUS POLYPROPYLENE MESH FOR THE REPAIR OF CONTAMINATED DEFECTS OF THE ABDOMINAL-WALL

    NARCIS (Netherlands)

    BLEICHRODT, RP; SIMMERMACHER, RKJ; VANDERLEI, B; SCHAKENRAAD, JM

    Contaminated defects of the abdominal wall continue to be a significant problem for patients and surgeons. The lack of sufficient tissue may require the insertion of a prosthetic material. Polypropylene (PP) mesh is still the most widely used material for this purpose, although the propensity to

  2. Second Generation Self-Inflating Tissue Expanders: A Two-Year Experience

    Directory of Open Access Journals (Sweden)

    Jamal Omran Al Madani

    2014-01-01

    Full Text Available Background. Tissue expansion is a well-established surgical technique that produces an additional amount of normal skin to cover a defect. This technique is appealing because the skin quality and color are from the patient’s own. The widely used injectable expanders are of great reliability but carry the disadvantage of being painful during injection and most of the time require multiple clinic visits. So the idea of self-inflation became attractive and hydrogel expanders were developed and became widely known for being painless during clinic visit and decrease number of visits. The first generation expanders were modified by adding an enclosing plastic shell to decrease the unopposed expansion that occurred in the first generation expanders, which lead to pressure necrosis of the skin flaps. This made it an attractive option for tissue expansion in children and some adult patients. Patients, Materials, and Methods. Charts of 17 patients were retrospectively reviewed, all of them had second generation self-inflating expanders implanted over a 2-year period for one of two purposes, the treatment of giant nevi or burn scars. Results. Fifteen patients were females and 2 were males. The indication was large burn scar in 14 cases (14/17, in which 47/55 expanders were implanted, and giant nevus in 3/17 cases in which 8/55 expanders were implanted. Extrusion of the expander occurred in 8/55 expanders (14.5%, which occurred in 6/14 patients. The highest percentage of extrusion occurred in the neck in which two out of three expanders extruded; otherwise this complication does not seem to be related to the indication, gender, nor age of the patients. It seems to be that it is technical in nature. The patients did not have to get any injections to fill the tissue expanders, which made the expansion process less painful and more convenient. Conclusion. This seems to be currently the largest published review in which second generation expanders were used

  3. Preparation Nano-Structure Polytetrafluoroethylene (PTFE Functional Film on the Cellulose Insulation Polymer and Its Effect on the Breakdown Voltage and Hydrophobicity Properties

    Directory of Open Access Journals (Sweden)

    Jian Hao

    2018-05-01

    Full Text Available Cellulose insulation polymer is an important component of oil-paper insulation, which is widely used in power transformer. The weight of the cellulose insulation polymer materials is as high as tens of tons in the larger converter transformer. Excellent performance of oil-paper insulation is very important for ensuring the safe operation of larger converter transformer. An effective way to improve the insulation and the physicochemical property of the oil impregnated insulation pressboard/paper is currently a popular research topic. In this paper, the polytetrafluoroethylene (PTFE functional film was coated on the cellulose insulation pressboard by radio frequency (RF magnetron sputtering to improve its breakdown voltage and the hydrophobicity properties. X-ray photoelectron spectroscopy (XPS results show that the nano-structure PTFE functional film was successfully fabricated on the cellulose insulation pressboard surface. The scanning electron microscopy (SEM and X-ray diffraction (XRD present that the nanoscale size PTFE particles were attached to the pressboard surface and it exists in the amorphous form. Atomic force microscopy (AFM shows that the sputtered pressboard surface is still rough. The rough PTFE functional film and the reduction of the hydrophilic hydroxyl of the surface due to the shielding effect of PTFE improve the breakdown and the hydrophobicity properties of the cellulose insulation pressboard obviously. This paper provides an innovative way to improve the performance of the cellulose insulation polymer.

  4. Strength analysis of expandable tubulars for well applications

    Energy Technology Data Exchange (ETDEWEB)

    Aguiar, A.C.C. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil); Fonseca, C.E. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil); Netto, T.A. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE)

    2008-07-01

    Solid expandable tube technology has many advantages when compared to conventional wells. The expansion of tubes in situ allows developing reserves in many of the challenging scenarios found in oil industry, as pre-salt layer, HPHT wells, deep reservoirs, or ultra-deep water. Besides, this procedure has good compatibility with directional and horizontal wells and facilitates side-tracks operations. Although the expansion of tubes is very attractive, a better understanding of its influence on the tube mechanical strength is necessary. In this work, experimental tests and numerical analyses were performed in order to determine the effect of parameters such as diameter-to-thickness ratio and expansion rate on the collapse resistance of expandable tubes. An experimental apparatus was designed and built to reproduce full-scale tube expansion. Three 2 meter long specimens were expanded 10% their original diameters and subjected to hydrostatic pressure inside a vessel until collapse. Three non-expanded tubes were also tested for comparison. At the same time, non-linear numerical models were developed using the finite element method. After calibration, they were used to further analyze the mechanical behavior of solid expandable tubes and the influence of expansion on its resistance against collapse. (author)

  5. An Isothermal Steam Expander for an Industrial Steam Supplying System

    Directory of Open Access Journals (Sweden)

    Chen-Kuang Lin

    2015-01-01

    Full Text Available Steam is an essential medium used in the industrial process. To ensure steam quality, small and middle scale boilers are often adopted. However, because a higher steam pressure (compared to the necessary steam pressure is generated, the boiler’s steam pressure will be reduced via a pressure regulator before the steam is directed through the process. Unfortunately, pressure is somewhat wasted during the reducing process. Therefore, in order to promote energy efficiency, a pressure regulator is replaced by a steam expander. With this steam expander, the pressure will be transformed into mechanical energy and extracted during the expansion process. A new type of isothermal steam expander for an industrial steam supplying system will be presented in the paper. The isothermal steam expander will improve the energy efficiency of a traditional steam expander by replacing the isentropic process with an isothermal expansion process. With this, steam condensation will decrease, energy will increase, and steam quality will be improved. Moreover, the mathematical model of the isothermal steam expander will be established by using the Schmidt theory, the same principle used to analyze Stirling engines. Consequently, by verifying the correctness of the theoretical model for the isothermal steam expander using experimental data, a prototype of 100 c.c. isothermal steam expander is constructed.

  6. Numerical modelling of multi-vane expander operating conditions in ORC system

    Science.gov (United States)

    Rak, Józef; Błasiak, Przemysław; Kolasiński, Piotr

    2017-11-01

    Multi-vane expanders are positive displacement volumetric machines which are nowadays considered for application in micro-power domestic ORC systems as promising alternative to micro turbines and other volumetric expanders. The multi-vane expander features very simple design, low gas flow capacity, low expansion ratios, an advantageous ratio of the power output to the external dimensions and are insensitive to the negative influence of the gas-liquid mixture expansion. Moreover, the multi-vane expander can be easily hermetically sealed, which is one of the key issues in the ORC system design. A literature review indicates that issues concerning the application of multi-vane expanders in such systems, especially related to operating of multi-vane expander with different low-boiling working fluids, are innovative, not fully scientifically described and have the potential for practical implementation. In this paper the results of numerical investigations on multi-vane expander operating conditions are presented. The analyses were performed on three-dimensional numerical model of the expander in ANSYS CFX software. The numerical model of the expander was validated using the data obtained from the experiment carried out on a lab test-stand. Then a series of computational analysis were performed using expanders' numerical model in order to determine its operating conditions under various flow conditions of different working fluids.

  7. The Presidential Sweepstakes 2000.

    Science.gov (United States)

    Doyle, Denis P.

    2000-01-01

    In the 2000 presidential campaigns, both Vice-President Al Gore and Texas Governor George W. Bush want to enlarge the federal role in education. In separate essays, Bush and Gore explain their plans to invest more federal dollars in improving poor children's educational progress and opportunities. (MLH)

  8. Understanding Business Strategies of Networked Value Constellations Using Goal- and Value Modeling

    NARCIS (Netherlands)

    Gordijn, Jaap; Petit, Michael; Wieringa, Roelf J.

    2006-01-01

    In goal-oriented requirements engineering (GORE), one usually proceeds from a goal analysis to a requirements specification, usually of IT systems. In contrast, we consider the use of GORE for the design of IT-enabled value constellations, which are collections of enterprises that jointly satisfy a

  9. ZIP4H (TEX11 deficiency in the mouse impairs meiotic double strand break repair and the regulation of crossing over.

    Directory of Open Access Journals (Sweden)

    Carrie A Adelman

    2008-03-01

    Full Text Available We have recently shown that hypomorphic Mre11 complex mouse mutants exhibit defects in the repair of meiotic double strand breaks (DSBs. This is associated with perturbation of synaptonemal complex morphogenesis, repair and regulation of crossover formation. To further assess the Mre11 complex's role in meiotic progression, we identified testis-specific NBS1-interacting proteins via two-hybrid screening in yeast. In this screen, Zip4h (Tex11, a male germ cell specific X-linked gene was isolated. Based on sequence and predicted structural similarity to the S. cerevisiae and A. thaliana Zip4 orthologs, ZIP4H appears to be the mammalian ortholog. In S. cerevisiae and A. thaliana, Zip4 is a meiosis-specific protein that regulates the level of meiotic crossovers, thus influencing homologous chromosome segregation in these organisms. As is true for hypomorphic Nbs1 (Nbs1(DeltaB/DeltaB mice, Zip4h(-/Y mutant mice were fertile. Analysis of spermatocytes revealed a delay in meiotic double strand break repair and decreased crossover formation as inferred from DMC1 and MLH1 staining patterns, respectively. Achiasmate chromosomes at the first meiotic division were also observed in Zip4h(-/Y mutants, consistent with the observed reduction in MLH1 focus formation. These results indicate that meiotic functions of Zip4 family members are conserved and support the view that the Mre11 complex and ZIP4H interact functionally during the execution of the meiotic program in mammals.

  10. Expanded-bed chromatography in primary protein purification.

    Science.gov (United States)

    Anspach, F B; Curbelo, D; Hartmann, R; Garke, G; Deckwer, W D

    1999-12-31

    Chromatography in stable expanded beds enables proteins to be recovered directly from cultivations of microorganisms or cells and preparations of disrupted cells, without the need for prior removal of suspended solids. The general performance of an expanded bed is comparable to a packed bed owing to reduced mixing of the adsorbent particles in the column. However, optimal operating conditions are more restricted than in a packed bed due to the dependence of bed expansion on the size and density of the adsorbent particles as well as the viscosity and density of the feedstock. The feedstock composition may become the most limiting restriction owing to interactions of adsorbent particles with cell surfaces, DNA and other substances, leading to their aggregation and consequently to bed instabilities and channeling. Despite these difficulties, expanded-bed chromatography has found widespread applications in the large scale purification of proteins from mammalian cell and microbial feedstocks in industrial bioprocessing. The basics and implementation of expanded-bed chromatography, its advantages as well as problems encountered in the use of this technique for the direct extraction of proteins from unclarified feedstocks are addressed.

  11. First order phase transition of expanding matter and its fragmentation

    International Nuclear Information System (INIS)

    Chikazumi, Shinpei; Iwamoto, Akira

    2002-01-01

    Using an expanding matter model with a Lennard-Jones potential, the instability of the expanding system is investigated. The pressure, the temperature, and the density fluctuations are calculated as functions of density during the time evolution of the expanding matter, which are compared to the coexistence curve calculated by the Gibbs ensemble. The expanding matter undergoes the first order phase transition in the limit of the quasistatic expansion. The resultant fragment mass distributions are also investigated. (author)

  12. [E-PTFE Membrane for the Management of Perforated Corneal Ulcer].

    Science.gov (United States)

    Pahor, D; Pahor, A

    2016-10-01

    Purpose: To present the surgical management of perforated corneal ulcer using PRECLUDE® Pericardial Membrane, composed of expanded polytetrafluoroethylene (e-PTFE; GORE-TEX®), as an alternative surgical procedure in patients at high risk of graft rejections and to evaluate side effects for a prolonged period. Patients and Methods: The study included all patients who were admitted to our department and underwent surgical repair of perforated corneal ulcer with the e-PTFE membrane between 2010 and 2015. In total, 8 patients (8 eyes) were enrolled. Medical records of all patients were retrospectively reviewed. The operation was performed under peribulbar anaesthesia. Non-absorbable, microporous, watertight 0.1 mm thick e-PTFE membrane was used to close the corneal ulcer. The membrane was cut to overlap the defect adequately and to achieve the desired tissue attachment without preparing the conjunctiva or superficial trephination of the cornea. The membrane was fixed to the healthy cornea with several non-absorbable sutures (Prolene® 10.0), in order to achieve the proper stress without wrinkling. Results: Five of 8 patients were treated for systemic immunological diseases. Sjögren's syndrome was diagnosed in 2 patients, granulomatosis with polyangiitis in one, vasculitis with a history of previous sclerokeratitis in one and systemic lupus erythematosus in one. In 2 patients, corneal perforation was observed as a complication of corneal infection and in one patient as a late complication of a severe chemical burn. Corneal perforations were successfully covered with e-PTFE membrane in all patients. E-PTFE membrane was well tolerated in all patients and the eye was always preserved. After 3 to 4 months, the membrane was removed in 7 patients. The underlying cornea was thin, firm, stable and vascularised. In one patient with Sjögren's syndrome, the e-PTFE membrane is still in place. Conclusion: Surgical management of perforated corneal ulcer using E-PTFE membrane

  13. PREFACE: Proceedings of the First International Workshop on the Theoretical Calculation of ELNES and XANES (TEX2008) (Nagoya, Japan, 2-4 July 2008) Proceedings of the First International Workshop on the Theoretical Calculation of ELNES and XANES (TEX2008) (Nagoya, Japan, 2-4 July 2008)

    Science.gov (United States)

    Tanaka, Isao; Mizoguchi, Teruyasu; Yamamoto, Tomoyuki

    2009-03-01

    -or-less independently by the two communities. The three-day workshop on the Theoretical Calculation of ELNES and XANES (TEX2008) was planned to help remedy this situation. It aimed to demonstrate capability of state-of-the-art theoretical techniques to explain and predict ELNES and XANES spectra, and to allow deep discussion between scientists in the two communities. It also provided an excellent opportunity to introduce experimentalists to the computational techniques available. Invited talks and poster presentations by leading scientists were given on the first day, which was followed by tutorial sessions for five computer programs on the second and third days. Excellent lectures were given by Peter Blaha (Vienna, Austria) on the WIEN2k code, Chris J Pickard (St Andrews, UK) on the CASTEP code, John J Rehr (Seattle, USA) on the FEFF8 code, Frank de Groot (Utrecht, The Netherlands) on the CTM4XAS code, and Hidekazu Ikeno (Kyoto, Japan) on the first-principles CI-multiplet code. Thanks to the enthusiastic participation of more than 100 scientists from around the world, the workshop was a complete success. The aim of this special issue in Journal of Physics: Condensed Matter is to share with the readers the most up-to-date knowledge presented at the workshop. We believe this will prove useful as a reference for researchers in many different fields, as well as an overview of the current status and future directions of theoretical calculations for ELNES and XANES. TEX2008 was a satellite meeting of the First International Symposium on Advanced Microscopy and Theoretical Calculations (AMTC1) (Nagoya, Japan, 29-30 June 2008), which was held in commemoration of the establishment of the Nanostuctures Research Laboratory (NSRL) at the Japan Fine Ceramics Center (JFCC) and as a daughter event of EXPO 2005, Aichi, Japan. A Grant-in-Aid for Scientific Research on Priority Areas 'Nano Materials Science for Atomic-Scale Modification' from the Ministry of Education, Culture, Sports and Technology

  14. Grazing incidence beam expander

    Energy Technology Data Exchange (ETDEWEB)

    Akkapeddi, P.R.; Glenn, P.; Fuschetto, A.; Appert, Q.; Viswanathan, V.K.

    1985-01-01

    A Grazing Incidence Beam Expander (GIBE) telescope is being designed and fabricated to be used as an equivalent end mirror in a long laser resonator cavity. The design requirements for this GIBE flow down from a generic Free Electron Laser (FEL) resonator. The nature of the FEL gain volume (a thin, pencil-like, on-axis region) dictates that the output beam be very small. Such a thin beam with the high power levels characteristic of FELs would have to travel perhaps hundreds of meters or more before expanding enough to allow reflection from cooled mirrors. A GIBE, on the other hand, would allow placing these optics closer to the gain region and thus reduces the cavity lengths substantially. Results are presented relating to optical and mechanical design, alignment sensitivity analysis, radius of curvature analysis, laser cavity stability analysis of a linear stable concentric laser cavity with a GIBE. Fabrication details of the GIBE are also given.

  15. The Expanded Large Scale Gap Test

    Science.gov (United States)

    1987-03-01

    NSWC TR 86-32 DTIC THE EXPANDED LARGE SCALE GAP TEST BY T. P. LIDDIARD D. PRICE RESEARCH AND TECHNOLOGY DEPARTMENT ’ ~MARCH 1987 Ap~proved for public...arises, to reduce the spread in the LSGT 50% gap value.) The worst charges, such as those with the highest or lowest densities, the largest re-pressed...Arlington, VA 22217 PE 62314N INS3A 1 RJ14E31 7R4TBK 11 TITLE (Include Security CIlmsilficatiorn The Expanded Large Scale Gap Test . 12. PEIRSONAL AUTHOR() T

  16. Laparoscopic creation of neovagina and neocervix, followed by their reconstruction with polytetrafluoroethylene graft/buccal mucosa and pudendal artery perforator flap

    Directory of Open Access Journals (Sweden)

    Yi-Chieh Li

    2015-11-01

    Full Text Available Congenital cervical agenesis of is a rare Müllerian anomaly that may be associated with partial or complete vaginal aplasia and renal anomalies. Symptoms such as amenorrhea and abdominal pain usually develop shortly after menarche, when the absence or obstruction of the cervical canal results in blood accumulation in the uterus and fallopian tubes, and finally in the peritoneal cavity. Physical examination sometimes reveals normally developed external sex organs. Delayed diagnosis and treatment may potentially result in extensive endometriosis, which may potentially cause severe adhesion and damage to reproductivity. Such consequences could complicate further the management of the disease. Traditionally, hysterectomy has been the treatment of choice in these cases because of the high failure rate of canalization procedures and risk of serious ascending infection. With advanced laparoscopic techniques, conservative management seems feasible and has been recommended. We herein present a patient with complete cervical and vaginal agenesis. Creation of a neovagina and uterovaginal anastomosis were performed first under the guidance of laparoscopy (Figure 1. A neocervix was composed of a polytetrafluoroethylene graft and a piece of oral mucosa retrieved from the buccal area. The neovagina was reconstructed with an external pudendal artery perforator flap. A cervical Fr 16 size Foley was left in place as a stent. The patient had uneventful postoperative recovery and fair wound healing at the outpatient follow-up. Congenital agenesis of the uterine cervix and vagina can be differentiated accurately and reconstructed laparoscopically. Using mesh-buccal mucosa composite and pudendal perforator flap is a practical way to reconstruct neocervix and neovagina after their creation.

  17. Acquisition of reproducible transmission near-infrared (NIR) spectra of solid samples with inconsistent shapes by irradiation with isotropically diffused radiation using polytetrafluoroethylene (PTFE) beads.

    Science.gov (United States)

    Lee, Jinah; Duy, Pham Khac; Yoon, Jihye; Chung, Hoeil

    2014-06-21

    A bead-incorporated transmission scheme (BITS) has been demonstrated for collecting reproducible transmission near-infrared (NIR) spectra of samples with inconsistent shapes. Isotropically diffused NIR radiation was applied around a sample and the surrounding radiation was allowed to interact homogeneously with the sample for transmission measurement. Samples were packed in 1.40 mm polytetrafluoroethylene (PTFE) beads, ideal diffusers without NIR absorption, and then transmission spectra were collected by illuminating the sample-containing beads using NIR radiation. When collimated radiation was directly applied, a small portion of the non-fully diffused radiation (NFDR) propagated through the void space of the packing and eventually degraded the reproducibility. Pre-diffused radiation was introduced by placing an additional PTFE disk in front of the packing to diminish NFDR, which produced more reproducible spectral features. The proposed scheme was evaluated by analyzing two different solid samples: density determination for individual polyethylene (PE) pellets and identification of mining locality for tourmalines. Because spectral collection was reproducible, the use of the spectrum acquired from one PE pellet was sufficient to accurately determine the density of nine other pellets with different shapes. The differentiation of tourmalines, which are even more dissimilar in appearance, according to their mining locality was also feasible with the help of the scheme.

  18. Numerical modelling of multi-vane expander operating conditions in ORC system

    Directory of Open Access Journals (Sweden)

    Rak Józef

    2017-01-01

    Full Text Available Multi-vane expanders are positive displacement volumetric machines which are nowadays considered for application in micro-power domestic ORC systems as promising alternative to micro turbines and other volumetric expanders. The multi-vane expander features very simple design, low gas flow capacity, low expansion ratios, an advantageous ratio of the power output to the external dimensions and are insensitive to the negative influence of the gas-liquid mixture expansion. Moreover, the multi-vane expander can be easily hermetically sealed, which is one of the key issues in the ORC system design. A literature review indicates that issues concerning the application of multi-vane expanders in such systems, especially related to operating of multi-vane expander with different low-boiling working fluids, are innovative, not fully scientifically described and have the potential for practical implementation. In this paper the results of numerical investigations on multi-vane expander operating conditions are presented. The analyses were performed on three-dimensional numerical model of the expander in ANSYS CFX software. The numerical model of the expander was validated using the data obtained from the experiment carried out on a lab test-stand. Then a series of computational analysis were performed using expanders' numerical model in order to determine its operating conditions under various flow conditions of different working fluids.

  19. Prosthetic above-knee femoropopliteal bypass grafting: five-year results of a randomized trial.

    Science.gov (United States)

    Green, R M; Abbott, W M; Matsumoto, T; Wheeler, J R; Miller, N; Veith, F J; Money, S; Garrett, H E

    2000-03-01

    This trial was designed to identify factors affecting patency rates of primary prosthetic above-knee femoropopliteal bypass grafts at 5 years. A multi-institutional, prospective trial randomized 240 patients to compare patency rates of Gore-tex and Hemashield above-knee femoropopliteal bypass grafts at 5 years. Univariate comparisons of patency between levels of each prognostic variable were made with the Kaplan-Meier method. Variables that had a univariate P value less than.25 or those known to be important were submitted to a Cox regression analysis. The patient survival rate at 5 years was 59.4%. There were no differences in primary or secondary patency rates at 5 years between the two graft materials (primary, 45% vs 43% and secondary, 68% vs 68%). The risk for graft occlusion was significantly increased for patients younger than 65 years (2.1; P =.001) and for grafts with a diameter less than 7 mm (1.65; P =.0219). Variables with no apparent independent effect on patency rates were smoking status, runoff, diabetes mellitus, sex, presenting symptoms, and postoperative treatment with aspirin or Coumadin. Noninvasive test results were not predictive of subsequent graft function. Although the type of prosthetic used for above-knee femoropopliteal bypass grafts does not affect 5-year patency rates, age and graft size do influence results. These factors should be considered before a prosthetic bypass grafting procedure. Furthermore, these data should serve as a contemporary standard, with which evolving and conventional procedures can be compared.

  20. Legal and Institutional Constraints on Aquaculture in Dredged Material Containment Areas

    Science.gov (United States)

    1993-04-01

    SIZED CLAM PERMIT: It is unlawful to take, harvest, possess, sell, purchase, or import any hard clam of the genus Mercenaria of less than one inch in...S.W.2d 212, 216 (Tex.App. 19b?’ Bily v. Omni Equities . Inc., 731 S.W.2d 606, 611-12 (Tex.App. 1987); see also Tex. [Civ. Prac. & Rem.] Code Ann

  1. Conference Offers Girls Opportunity to Expand Career Horizons

    Science.gov (United States)

    Offers Girls Opportunity to Expand Career Horizons For more information contact: e:mail: Public Affairs Golden, Colo., Feb. 11, 1997 -- Expanding Your Horizons, a conference for girls grades 6 - 9 and Employed Women, Girls Incorporated of Metro Denver, King Soopers, McDonalds, the TCI Adult Program and the

  2. Development of cryogenic free-piston reciprocating expander utilizing phase controller

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Jeong Min; Park, Ji Ho; Kim, Kyung Joong; Jeong, Sang Kwon [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2016-06-15

    A free-piston reciprocating expander is a device which operates without any mechanical linkage to a stationary part. Since the motion of the floating piston is only controlled by the pressure difference at two ends of the piston, this kind of expander may indispensably require a sophisticated active control system equipped with multiple valves and reservoirs. In this paper, we have suggested a novel design that can further reduce complexity of the previously developed cryogenic free-piston expander configuration. It is a simple replacement of both multiple valves and reservoirs by a combination of an orifice valve and a reservoir. The functional characteristic of the integrated orifice-reservoir configuration is similar to that of a phase controller applied in a pulse tube refrigerator so that we designate the one as a phase controller. Depending on the orifice valve size in the phase controller, the different PV work which affects the expander performance is generated. The numerical model of this unique free-piston reciprocating expander utilizing a phase controller is established to understand and analyze quantitatively the performance variation of the expander under different valve timing and orifice valve size. The room temperature experiments are carried out to examine the performance of this newly developed cryogenic expander.

  3. Development of cryogenic free-piston reciprocating expander utilizing phase controller

    International Nuclear Information System (INIS)

    Cha, Jeong Min; Park, Ji Ho; Kim, Kyung Joong; Jeong, Sang Kwon

    2016-01-01

    A free-piston reciprocating expander is a device which operates without any mechanical linkage to a stationary part. Since the motion of the floating piston is only controlled by the pressure difference at two ends of the piston, this kind of expander may indispensably require a sophisticated active control system equipped with multiple valves and reservoirs. In this paper, we have suggested a novel design that can further reduce complexity of the previously developed cryogenic free-piston expander configuration. It is a simple replacement of both multiple valves and reservoirs by a combination of an orifice valve and a reservoir. The functional characteristic of the integrated orifice-reservoir configuration is similar to that of a phase controller applied in a pulse tube refrigerator so that we designate the one as a phase controller. Depending on the orifice valve size in the phase controller, the different PV work which affects the expander performance is generated. The numerical model of this unique free-piston reciprocating expander utilizing a phase controller is established to understand and analyze quantitatively the performance variation of the expander under different valve timing and orifice valve size. The room temperature experiments are carried out to examine the performance of this newly developed cryogenic expander

  4. Enterocutaneous fistula associated with ePTFE mesh: case report and review of the literature.

    Science.gov (United States)

    Foda, M; Carlson, M A

    2009-06-01

    A case of enterocutaneous fistula secondary to the erosion of an expanded polytetrafluoroethylene (ePTFE) prosthesis into the jejunum is described. This case is unusual secondary to the long experience with ePTFE and the lack of published cases similar to this one. The technical details of this case reveal extenuating circumstances associated with the fistula formation, and it is concluded that this particular case does not provide sufficient evidence to implicate ePTFE, by itself, as an etiologic agent for gastrointestinal fistulization. In addition, the published safety record of ePTFE in abdominal wall surgery is reviewed.

  5. Fabricating PFPE Membranes for Microfluidic Valves and Pumps

    Science.gov (United States)

    Greer, Frank; White, Victor E.; Lee, Michael C.; Willis, Peter A.; Grunthaner, Frank J.; Rolland, Jason; Rolland, Jason

    2009-01-01

    A process has been developed for fabricating membranes of a perfluoropolyether (PFPE) and integrating them into valves and pumps in laboratory-on-achip microfluidic devices. Membranes of poly(tetrafluoroethylene) [PTFE] and poly(dimethylsilane) [PDMS] have been considered for this purpose and found wanting. By making it possible to use PFPE instead of PTFE or PDMS, the present process expands the array of options for further development of microfluidic devices for diverse applications that could include detection of biochemicals of interest, detection of toxins and biowarfare agents, synthesis and analysis of proteins, medical diagnosis, and synthesis of fuels.

  6. Percutaneous Endoluminal Stent-Graft Repair of an Old Traumatic Femoral Arteriovenous Fistula

    International Nuclear Information System (INIS)

    Uflacker, Renan; Elliott, Bruce M.

    1996-01-01

    A stent-graft was custom made to close a high-flow traumatic arteriovenous fistula of the left superficial femoral artery, present for 30 years, in a 60-year-old man with congestive heart failure and ischemic ulceration in the left foot. A balloon expandable Palmaz stent (P394; 2.5 mm x 3.9 cm) was covered with a polytetrafluoroethylene (PTFE) graft and was inserted percutaneously through an 11 Fr vascular sheath. Follow-up Doppler ultrasound at 6 months demonstrated occlusion of the arteriovenous fistula, patency of the artery, and luminal integrity of the artery and vein

  7. Crystallization degree change of expanded graphite by milling and annealing

    International Nuclear Information System (INIS)

    Tang Qunwei; Wu Jihuai; Sun Hui; Fang Shijun

    2009-01-01

    Expanded graphite was ball milled with a planetary mill in air atmosphere, and subsequently thermal annealed. The samples were characterized by using X-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM) and thermal gravimetric analysis (TGA). It was found that in the milling initial stage (less than 12 h), the crystallization degree of the expanded graphite declined gradually, but after milling more than 16 h, a recrystallization of the expanded graphite toke place, and ordered nanoscale expanded graphite was formed gradually. In the annealing initial stage, the non-crystallization of the graphite occurred, but, beyond an annealing time, recrystallizations of the graphite arise. Higher annealing temperature supported the recrystallization. The milled and annealed expanded graphite still preserved the crystalline structure as raw material and hold high thermal stability.

  8. Politics and the Environmental Agenda.

    Science.gov (United States)

    Rogers, Adam

    1992-01-01

    Discusses the role of environmental protection in the 1992 presidential election. Includes an analysis of the positions taken by George Bush and Dan Quayle, Bill Clinton and Al Gore. Presents George Bush's "environmental" record during his tenure as President of the United States as well as those of Quayle, Gore, and Clinton. (MCO)

  9. Resonance – Journal of Science Education | Indian Academy of ...

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education. Bhalchandra W Gore. Articles written in Resonance – Journal of Science Education. Volume 22 Issue 7 July 2017 pp 705-714 Classroom. On Finding the Shortest Distance of a Point From a Line: Which Method Do You Prefer? Bhalchandra W Gore · More Details ...

  10. New York: Expanding Time, Increasing Opportunities for Achievement

    Science.gov (United States)

    Miller, Tiffany D.

    2014-01-01

    New York is poised to take an important step to improve student achievement by expanding learning time for students attending high-poverty, low-performing schools. Recent district- and state-level investments in expanded learning time--a promising strategy to close achievement and opportunity gaps--will give students more time to learn core…

  11. Innovative isothermal oil-free co-rotating scroll compressor–expander for energy storage with first expander tests

    International Nuclear Information System (INIS)

    Iglesias, A.; Favrat, D.

    2014-01-01

    Highlights: • Doing a new concept of small scale compressed air energy storage. • Presenting a new working process of scroll machinery. • Updating a thermodynamic model of scroll compressor that take into account water injection. • Updating a mathematical model of volumetric loses that take into account sealing effect of liquid water. • Encouraging results to investigate more deeply this new concept. - Abstract: The development of an efficient isothermal turbine and compressor is essential for the realization of a small-scale compressed air energy storage (CAES). This article presents the theoretical development of an oil-free co-rotating scroll air compressor and turbine working with water injection to make the operations of expansion and compression as isothermal as possible. First experimental results in expander mode are shown. The theoretical performance is predicted with the help of a mathematical model using the equations of energy and mass conservation and the equation of state. This model takes into account the effects of water injection and volumetric losses. The experimental prototype is an oil-free scroll air compressor with the distinctive feature of having two mobile involutes working in synchronized co-rotation one relative to another. The prime-mover is an electric motor driving the two scrolls with two synchronizing belts. Water injection in the housing intends to provide a quasi-isothermal compression. The same device is used as an isothermal expander by supplying high-pressure air with water when it rotates backwards in expander mode, the electric motor acting then as a generator. Expected improvements to a standard scroll compressor and expander are a better volumetric efficiency and a greater power density due to a higher rotational speed of the scrolls, thanks to their symmetrical masses. The isothermal processes increase also the overall performance

  12. Emission of perfluoroalkyl carboxylic acids (PFCA) from heated surfaces made of polytetrafluoroethylene (PTFE) applied in food contact materials and consumer products.

    Science.gov (United States)

    Schlummer, Martin; Sölch, Christina; Meisel, Theresa; Still, Mona; Gruber, Ludwig; Wolz, Gerd

    2015-06-01

    Polytetrafluoroethylene (PTFE) has been widely discussed as a source of perfluorooctanoic acid (PFOA), which has been used in the production of fluoropolymers. PTFE may also contain unintended perfluoroalkyl carboxylic acids (PFCAs) caused by thermolysis of PTFE, which has been observed at temperatures above 300°C. Common PTFE coated food contact materials and consumer goods are operated at temperatures above 200°C. However, knowledge on possible emissions of PFCAs is limited. Therefore, it was the aim of this study to investigate and evaluate the emission of PFCAs from PTFE coated products with both, normal use and overheating scenarios. Four pans, claimed to be PFOA free, and nine consumer products were investigated. At normal use conditions (PTFE surfaces were trapped for 1h. Overheating scenarios (>260°C) recorded emissions during a 30min heating of empty pans on a stove. Emissions were analyzed by LC-ESI-MS. Results indicate the emission of PFCAs, whereas no perfluorinated sulfonic acids were traced. At normal use conditions total emissions of PFCAs accounted for 4.75ng per hour. Overheated pans, however, released far higher amounts with up to 12190ng PFCAs per hour at 370°C. Dominating contributors where PFBA and PFOA at normal use and PFBA and PFPeA during overheating. Temperature seems to be the main factor controlling the emission of PFCAs. A worst case estimation of human exposure revealed that emissions of PFCAs from heated PTFE surfaces would be far below the TDI of 1500ng PFOA per kg body weight. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Is sonographic surveillance of polytetrafluoroethylene-covered transjugular intrahepatic portosystemic shunts (TIPS) necessary? A single centre experience comparing both types of stents

    Energy Technology Data Exchange (ETDEWEB)

    Pan, J.-J.; Chen, C. [Department of Medicine, Division of Gastroenterology, Hepatology, and Nutrition, Section of Hepatobiliary Disease, University of Florida, Gainesville, FL (United States); Geller, B. [Department of Radiology, University of Florida, Gainesville, FL (United States); Firpi, R.; Machicao, V.I. [Department of Medicine, Division of Gastroenterology, Hepatology, and Nutrition, Section of Hepatobiliary Disease, University of Florida, Gainesville, FL (United States); Caridi, J.G. [Department of Radiology, University of Florida, Gainesville, FL (United States); Nelson, D.R. [Department of Medicine, Division of Gastroenterology, Hepatology, and Nutrition, Section of Hepatobiliary Disease, University of Florida, Gainesville, FL (United States); Morelli, G. [Department of Medicine, Division of Gastroenterology, Hepatology, and Nutrition, Section of Hepatobiliary Disease, University of Florida, Gainesville, FL (United States)], E-mail: morelgj@medicine.ufl.edu

    2008-10-15

    Aim: To investigate whether sonographic (US) surveillance of polytetrafluoroethylene covered transjugular intrahepatic portosystemic shunts (TIPS) is necessary. Materials and methods: We identified 128 patients who underwent TIPS for complications of portal hypertension between January 2001 and December 2005 at a large tertiary centre. Procedural data were retrospectively analysed. US surveillance of the TIPS was performed at baseline with scheduled follow-up or whenever shunt dysfunction was suspected. Clinical and radiology reports were compared to assess US surveillance of the TIPS. Results: Four hundred and twenty-six US studies were performed, with a median of three per patient (range 1-5). The median follow-up period was 378 days (range 1-1749 days). Twenty-three patients (18%) had baseline US studies performed only whereas 105 (82%) also had follow-up studies. Forty-one (32%) of 128 patients [32 (78%) Wallstent, nine (22%) Viatorr] had Doppler ultrasound abnormalities noted. Venography was performed in all 41 patients. Abnormal venography and elevated hepatic venous pressure gradient (HVPG) was seen in 34 (82.9%) of the 41 patients [29 (85.3%) Wallstent, five (14.7%) Viatorr]. Among the 34 patients, 17 (50%) [13 (76.5%) Wallstent, four (23.5%) Viatorr] had venographic abnormalities noted at the hepatic venous end accompanied by increased HVPG. All four of the Viatorr patients had minor narrowing at the hepatic venous end and HVPG measurements that ranged 3-4 mm Hg above 12 mm Hg. Conclusion: Considering the improved patency of covered stents in TIPS, US surveillance may be superfluous after the baseline study.

  14. Expanding the Game Design Space

    DEFF Research Database (Denmark)

    Larsen, Lasse Juel; Majgaard, Gunver

    2016-01-01

    This article considers game design research in educational settings. Its focus is on how undergraduate students – particularly engineering students – learn computer game design. From observations conducted during our game design courses we have developed a model of expanded game design space...... layer establishes correspondence between formal elements of computer games and the structure of problem-based creativity. It addresses how game design challenges should be formulated and how creative solutions can be measured. The fourth and final layer demonstrates how clear framing can act....... It encapsulates the entire development process from the first ideas to the final game with emphasis on game design thinking. Our model of expanded game design space consists of four separate – yet interconnected – layers in the process of game development. The first layer addresses the importance of framing...

  15. Self-expanding/shrinking structures by 4D printing

    Science.gov (United States)

    Bodaghi, M.; Damanpack, A. R.; Liao, W. H.

    2016-10-01

    The aim of this paper is to create adaptive structures capable of self-expanding and self-shrinking by means of four-dimensional printing technology. An actuator unit is designed and fabricated directly by printing fibers of shape memory polymers (SMPs) in flexible beams with different arrangements. Experiments are conducted to determine thermo-mechanical material properties of the fabricated part revealing that the printing process introduced a strong anisotropy into the printed parts. The feasibility of the actuator unit with self-expanding and self-shrinking features is demonstrated experimentally. A phenomenological constitutive model together with analytical closed-form solutions are developed to replicate thermo-mechanical behaviors of SMPs. Governing equations of equilibrium are developed for printed structures based on the non-linear Green-Lagrange strain tensor and solved implementing a finite element method along with an iterative incremental Newton-Raphson scheme. The material-structural model is then applied to digitally design and print SMP adaptive lattices in planar and tubular shapes comprising a periodic arrangement of SMP actuator units that expand and then recover their original shape automatically. Numerical and experimental results reveal that the proposed planar lattice as meta-materials can be employed for plane actuators with self-expanding/shrinking features or as structural switches providing two different dynamic characteristics. It is also shown that the proposed tubular lattice with a self-expanding/shrinking mechanism can serve as tubular stents and grippers for bio-medical or piping applications.

  16. Analysis of a rotating spool expander for Organic Rankine Cycle applications

    Science.gov (United States)

    Krishna, Abhinav

    Increasing interest in recovering or utilizing low-grade heat for power generation has prompted a search for ways in which the power conversion process may be enhanced. Amongst the conversion systems, the Organic Rankine Cycle (ORC) has generated an enormous amount of interest amongst researchers and system designers. Nevertheless, component level technologies need to be developed and match the range of potential applications. In particular, technical challenges associated with scaling expansion machines (turbines) from utility scale to commercial scale have prevented widespread adoption of the technology. In this regard, this work focuses on a novel rotating spool expansion machine at the heart of an Organic Rankine Cycle. A comprehensive, deterministic simulation model of the rotating spool expander is developed. The comprehensive model includes a detailed geometry model of the spool expander and the suction valve mechanism. Sub-models for mass flow, leakage, heat transfer and friction within the expander are also developed. Apart from providing the ability to characterize the expander in a particular system, the model provides a valuable tool to study the impact of various design variables on the performance of the machine. The investigative approach also involved an experimental program to assess the performance of a working prototype. In general, the experimental data showed that the expander performance was sub-par, largely due to the mismatch of prevailing operating conditions and the expander design criteria. Operating challenges during the shakedown tests and subsequent sub-optimal design changes also detracted from performance. Nevertheless, the results of the experimental program were sufficient for a proof-of-concept assessment of the expander and for model validation over a wide range of operating conditions. The results of the validated model reveal several interesting details concerning the expander design and performance. For example, the match

  17. Rupture of an expander prosthesis mimics axillary cancer recurrence.

    LENUS (Irish Health Repository)

    Ismael, T

    2005-10-01

    Regional silicone gel migration from a ruptured breast implant has been reported at different locations including the upper extremity, chest wall muscles, axilla and back. We report a patient who presented with an axillary mass that mimicked a regional recurrence 5 years after breast cancer reconstruction with a latissimus dorsi musculocutaneous flap and silicon gel expander-prosthesis. Surgical exploration revealed that the mass contained silicone gel around the port of the breast expander that had ruptured. The mass was confluent with an intracapsular silicone leak through a tract along the tube of the expander port.

  18. Evidence for radiation induced crosslinking in polytetrafluoroethylene by means of high-resolution solid-state 19F high-speed MAS NMR

    International Nuclear Information System (INIS)

    Katoh, Etsuko; Sugisawa, Hisashi; Oshima, Akihiro; Tabata, Yoneho; Seguchi, Tadao; Yamazaki, Toshimasa

    1999-01-01

    Radiation effects on molecular structure of polytetrafluoroethylene (PTFE) were studied by high-resolution solid-state 19 F high speed magic angle spinning (HS MAS) NMR spectroscopy. Samples used for the NMR studies were prepared by electron beam irradiation of PTFE with a wide range of irradiation doses from 0.5-10 MGy in the molten state at 340 deg. C under oxygen-free atmosphere. While the non-irradiated PTFE displayed only an intense peak of the internal CF 2 , several new signals corresponding to CF 3 , CF 2 and CF groups were observed for the PTFE which was high temperature irradiated at 340 deg. C in oxygen-free atmosphere (hti-PTFE). Intensities of these new signals increased with an increase of irradiation dose. The present solid-state 19 F HS MAS NMR studies provide not only the first experimental evidence regarding the existence of crosslinking structure in hti-PTFE, directly detected as the CF signal, but also the crosslinking density which can be estimated from a proportion of the CF versus total fluorine signal intensities. The higher the irradiation dose, the higher the crosslinking density; hti-PTFE with 10 MGy contains one crosslinking site per approximately 24 CF 2 groups, while the hti-PTFE with 5 MGy contains one crosslinking site per approximately 36 CF 2 groups. Further, G value of crosslinking (G(x)) was estimated from the signal intensities of 19 F HS MAS NMR spectra. The highest G(x)-value, 1.85, was observed for the 2MGy hti-PTFE sample, suggesting that crosslinking of PTFE is formed most efficaciously with 2 MGy irradiation in the molten state at 340 deg. C under oxygen-free atmosphere

  19. Hubble Diagram Test of Expanding and Static Cosmological Models: The Case for a Slowly Expanding Flat Universe

    Directory of Open Access Journals (Sweden)

    Laszlo A. Marosi

    2013-01-01

    Full Text Available We present a new redshift (RS versus photon travel time ( test including 171 supernovae RS data points. We extended the Hubble diagram to a range of z = 0,0141–8.1 in the hope that at high RSs, the fitting of the calculated RS/ diagrams to the observed RS data would, as predicted by different cosmological models, set constraints on alternative cosmological models. The Lambda cold dark matter (ΛCDM, the static universe model, and the case for a slowly expanding flat universe (SEU are considered. We show that on the basis of the Hubble diagram test, the static and the slowly expanding models are favored.

  20. Intermittency Statistics in the Expanding Solar Wind

    Science.gov (United States)

    Cuesta, M. E.; Parashar, T. N.; Matthaeus, W. H.

    2017-12-01

    The solar wind is observed to be turbulent. One of the open questions in solar wind research is how the turbulence evolves as the solar wind expands to great distances. Some studies have focused on evolution of the outer scale but not much has been done to understand how intermittency evolves in the expanding wind beyond 1 AU (see [1,2]). We use magnetic field data from Voyager I spacecraft from 1 to 10AU to study the evolution of statistics of magnetic discontinuities. We perform various statistical tests on these discontinuities and make connections to the physical processes occurring in the expanding wind.[1] Tsurutani, Bruce T., and Edward J. Smith. "Interplanetary discontinuities: Temporal variations and the radial gradient from 1 to 8.5 AU." Journal of Geophysical Research: Space Physics 84.A6 (1979): 2773-2787.[2] Greco, A., et al. "Evidence for nonlinear development of magnetohydrodynamic scale intermittency in the inner heliosphere." The Astrophysical Journal 749.2 (2012): 105.