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Sample records for ptfe vessel acid

  1. Renal vessel reconstruction in kidney transplantation using a polytetrafluoroethylene (PTFE) vascular graft.

    Science.gov (United States)

    Kamel, Mohamed H; Thomas, Anil A; Mohan, Ponnusamy; Hickey, David P

    2007-04-01

    We report a rare experience in reconstructing short renal vessels in kidney transplantation using polytetrafluroethylene (PTFE) vascular grafts. The short renal vessels in three kidney grafts were managed by the interposition of PTFE vascular grafts. Two grafts were from deceased donors and the third was a renal auto-transplant graft. PTFE grafts were used to lengthen short renal veins in two kidney grafts and a short renal artery in one. The warm ischaemia time was under 1 h and all kidneys functioned well post-operatively. Excellent blood perfusion in the three renal grafts was present on postoperative MAG 3 renal scan. No intra-operative or post-operative complications were encountered. In the three described patients, the use of PTFE vascular graft presented no additional morbidity to the kidney transplant operation and no post-oerative complication was related to its use. However, more data are necessary to conclude that PTFE graft can be used safely in kidney transplantation.

  2. Acid Aging Effects on Surfaces of PTFE Gaskets Investigated by Thermal Analysis

    Directory of Open Access Journals (Sweden)

    C. Fragassa

    2016-12-01

    Full Text Available This paper investigates the effect of a prolonged acid attack on the surface of PTFE by Thermogravimetric Analysis (TGA and Differential Scanning Calorimetry (DSC. PTFE is very non-reactive, partly because of the strength of carbon–fluorine bonds and for its high crystallinity, and, as a consequence, it is often used in containers and pipework with reactive and corrosive chemicals. The PTFE under analysis is commercialized by two alternative producers in form of Teflon tapes. These tapes are adopted, as gaskets, in process plants where tires moulds are cleaned by acid solutions inside a multistage ultrasonic process. In this case, PTFE shows, in a relatively short operation time, inexplicably phenomena of surface degradation, which could be related, in general terms, to an acid attack. But, even considering the combined effect of ultrasonic waves, temperature, humidity and acid attack, the PTFE properties of resistance nominally exclude the risk of the extreme erosion phenomena as observed. The present experimental research aim at investigating this contradiction. A possible explanation could be related to the presence in the cleaning solution of unexpected fluorides, able to produce fluorinating agents and, thus, degrade carbon-fluorine bonds. Considering more the 300 chemical elements a tire compound consists in, it is really complex to preserve the original chemical composition of the cleaning solution. In this research PTFE samples have been treated with different mixtures of acids with the aim at investigating the different aging effects. The thermal analysis has permitted the experimental characterization of PTFE surface properties after acid attack, providing evidence of the degradation phenomena. In particular, the different acid treatments adopted for accelerating the aging of gaskets have highlighted the different behaviour of the PTFE matrix, but also differences between manufacturers.

  3. Acid Aging Effects on Surfaces of PTFE Gaskets Investigated by Fourier Transform Infrared Spectroscopy

    Directory of Open Access Journals (Sweden)

    L. Giorgini

    2016-09-01

    Full Text Available This paper investigates the effect of a prolonged acid and thermal attack, on the surface of PTFE by Fourier Transform Infrared Micro-Spectroscopy (FT-IR. The materials are commercialized by two alternative producers in form of Teflon tapes. These tapes are installed in process plants where tires moulds are cleaned inside a multistage ultrasonic process. In these cases, Teflon tapes, having a role of gaskets, show inexplicably phenomena of degradation in relatively short operation periods. Even considering that these gaskets are exposed to the combined effect of ultrasonic waves, temperature, humidity and acid attack, the PTFE properties of resistance nominally exclude the possibility of these severe erosion phenomena. An interesting explanation can be related to the potential presence in the cleaning solution, mainly based on sulfamic acid, of highly reactive chemical compounds, as chlorides and fluorides, originated by the disaggregation of elements from the tire composition and/or additives used as processing aids and/or by catalytic effect generated by fluorine produced by PTFE degradation. In general, up to 300 different chemical elements, both organic and inorganic, natural and synthetic, are merged in a tire. Since this composition is practically unknown, especially regarding additives and “unusual elements”, representing a secrecy of each tire manufactures, it is really complex to define the chemical composition of the cleaning solution with an appropriate precision. As a consequence, the gaskets have been treated with different mixtures of acids in the way to combine a larger range of possibilities. Thus, the FT-IR experimental characterization of PTFE surface properties followed an appropriate accelerated aging, aiming at actuating the specific mechanics of wearing as in industrial use. The different acid treatments adopted for accelerating the aging of gaskets have highlighted the different behaviour of the PTFE matrix, but

  4. Studies on surface graft polymerization of acrylic acid onto PTFE film by remote argon plasma initiation

    International Nuclear Information System (INIS)

    Wang Chen; Chen Jierong

    2007-01-01

    The graft polymerization of acrylic acid (AAc) was carried out onto poly(tetrafluoroethylene) (PTFE) films that had been pretreated with remote argon plasma and subsequently exposed to oxygen to create peroxides. Peroxides are known to be the species responsible for initiating the graft polymerization when PTFE reacts with AAc. We chose different parameters of remote plasma treatment to get the optimum condition for introducing maximum peroxides (2.87 x 10 -11 mol/cm 2 ) on the surface. The influence of grafted reaction conditions on the grafting degree was investigated. The maximum grafting degree was 25.2 μg/cm 2 . The surface microstructures and compositions of the AAc grafted PTFE film were characterized with the water contact angle meter, Fourier-transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). Contact angle measurements revealed that the water contact angle decreased from 108 o to 41 o and the surface free energy increased from 22.1 x 10 -5 to 62.1 x 10 -5 N cm -1 by the grafting of the AAc chains. The hydrophilicity of the PTFE film surface was greatly enhanced. The time-dependent activity of the grafted surface was better than that of the plasma treated film

  5. THE USE OF CHLOROSULFONIC ACID ON SULFONATION OF cPTFE FILM GRAFTED STYRENE FOR PROTON EXCHANGE MEMBRANE

    Directory of Open Access Journals (Sweden)

    Yohan Yohan

    2010-06-01

    Full Text Available Sulfonation of g-ray iradiated and styrene-grafted crosslinked polytetrafluoro ethylene film (cPTFE-g-S film have been done. The aim of the research was to make hydrophyl membrane as proton exchange membrane fuel cell. Sulfonation was prepared by using chlorosulfonic acid in chloroethane under various conditions. The impact of the percentage of grafting, the concentration of chlorosulfonic acid, the reaction time,and the reaction temperature on the properties of sulfonated film were examined. The results show that sulfonation of surface-grafted films was incomplete at room temperature. Increasing concentration of chlorosulfonic acid and reaction temperature accelerate the reaction but they also favor side reactions. These lead to the decrease of the ion-exchange capacity, water uptake, and proton conductivity but the increase of the resistance to oxidation in a perhydrol solution. The resulted cPTFE-g-SS membraneis stabile in a H2O2 30% solution for 20 h.   Keywords: Chorosulfonic acid, sulfonation, PTFE film, proton excange membrane.

  6. Properties of PTFE tape as a semipermeable membrane in fluorous reactions

    OpenAIRE

    Brendon A. Parsons; Olivia Lin Smith; Myeong Chae; Veljko Dragojlovic

    2015-01-01

    Summary In a PTFE tape phase-vanishing reaction (PV-PTFE), a delivery tube sealed with PTFE tape is inserted into a vessel which contains the substrate. The reagent diffuses across the PTFE tape barrier into the reaction vessel. PTFE co-polymer films have been found to exhibit selective permeability towards organic compounds, which was affected by the presence of solvents. In this study, we attempted to establish general trends of permeability of PTFE tape to different compounds and to better...

  7. Radiation grafting of pH and thermosensitive N-isopropylacrylamide and acrylic acid onto PTFE films by two-steps process

    International Nuclear Information System (INIS)

    Bucio, E.; Burillo, G.

    2007-01-01

    Polytetrafluoroethylene (PTFE) was grafted (g) with acrylic acid (AAc) by γ-ray pre-irradiation method to get PTFE-g-AAc films, then N-isopropylacrylamide (NIPAAm) was grafted onto PTFE-g-AAc films with γ-ray to get (PTFE-g-AAc)-g-NIPAAm. PTFE films were irradiated in air at a dose rate of 3.0 kGy h -1 and different radiation dose. The irradiated films were placed in glass ampoules, which contained aqueous solutions with different monomer concentration (AAc), and then they were heated at different temperatures and reaction time. NIPAAm onto PTFE-g-AAc was carried out with the same procedure with monomer concentration of 1 mol L -1 . The thermosensitivity of the samples was defined and calculated as the ratio of the grafted samples swelling at 28 and 35 o C, and pH sensitivity defined as the ratio of the grafted samples swelling at pH 2 and 8

  8. 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.

  9. Properties of PTFE tape as a semipermeable membrane in fluorous reactions

    Directory of Open Access Journals (Sweden)

    Brendon A. Parsons

    2015-06-01

    Full Text Available In a PTFE tape phase-vanishing reaction (PV-PTFE, a delivery tube sealed with PTFE tape is inserted into a vessel which contains the substrate. The reagent diffuses across the PTFE tape barrier into the reaction vessel. PTFE co-polymer films have been found to exhibit selective permeability towards organic compounds, which was affected by the presence of solvents. In this study, we attempted to establish general trends of permeability of PTFE tape to different compounds and to better describe the process of solvent transport in PV-PTFE bromination reactions. Though PTFE tape has been reported as impermeable to some compounds, such as dimethyl phthalate, solvent adsorption to the tape altered its permeability and allowed diffusion through channels of solvent within the PTFE tape. In this case, the solvent-filled pores of the PTFE tape are chemically more akin to the adsorbed solvent rather than to the PTFE fluorous structure. The solvent uptake effect, which was frequently observed in the course of PV-PTFE reactions, can be related to the surface tension of the solvent and the polarity of the solvent relative to the reagent. The lack of pores in bulk PTFE prevents solvents from altering its permeability and, therefore, bulk PTFE is impermeable to most solvents and reagents. However, bromine, which is soluble in liquid fluorous media, diffused through the bulk PTFE. A better understanding of the PTFE phase barrier will make it possible to further optimize the PV-PTFE reaction design.

  10. Proton exchange membranes prepared by grafting of styrene/divinylbenzene into crosslinked PTFE membranes

    International Nuclear Information System (INIS)

    Li Jingye; Ichizuri, Shogo; Asano, Saneto; Mutou, Fumihiro; Ikeda, Shigetoshi; Iida, Minoru; Miura, Takaharu; Oshima, Akihiro; Tabata, Yoneho; Washio, Masakazu

    2005-01-01

    Thin PTFE membranes were prepared by coating the PTFE dispersion onto the aluminum films. Thus the thin crosslinked PTFE (RX-PTFE) membranes were obtained by means of electron beam irradiation above the melting temperature of PTFE under oxygen-free atmosphere. The RX-PTFE membranes were pre-irradiated and grafted by styrene with or without divinylbenzene (DVB) in liquid phase. The existence of DVB accelerated the initial grafting rate. The styrene grafted RX-PTFE membranes are white colored, on the other hand, the styrene/DVB grafted RX-PTFE membranes are colorless. The proton exchange membranes (PEMs) were obtained by sulfonating the grafted membranes using chlorosulfonic acid. The ion exchange capacity (IEC) values of the PEMs ranging from 1.5 to 2.8 meq/g were obtained. The PEMs made from the styrene/DVB grafted membranes showed higher chemical stability than those of the styrene grafted membranes under oxidative circumstance

  11. Diaphragms obtained by radiochemical grafting in PTFE

    International Nuclear Information System (INIS)

    Nenner, T.; Fahrasmane, A.

    1984-01-01

    Diaphragms for alkaline water electrolysis are prepared by radiochemical grafting of PTFE fabric with styrene, which is later on sulfonated, or with acrylic acid. The diaphragms obtained are mechanically resistant to potash at temperatures up to 200 0 C, but show some degrafting, which limits the lifetime. The sulfonated styrene group has been found to be more stable in electrolysis than the acrylic acid. In both cases, the incorporation of a cross-linking agent like divinyl benzene improves the lifetime of the diaphragms. Electrolysis during 500 hours at 120 0 C and 10 kAm 2 could be performed. (author)

  12. Mechanical Stability of H3PO4-Doped PBI/Hydrophilic-Pretreated PTFE Membranes for High Temperature PEMFCs

    International Nuclear Information System (INIS)

    Park, Jaehyung; Wang, Liang; Advani, Suresh G.; Prasad, Ajay K.

    2014-01-01

    Graphical abstract: - Highlights: • PBI/PTFE membrane was prepared by porous PTFE with hydrophilic surface pretreatment. • The durability of the prepared PBI/PTFE membrane was compared with pure PBI, PBI with untreated PTFE, and PBI-Nafion with untreated PTFE membranes. • Accelerated durability tests and SEM showed improved durability based the PBI/PTFE membrane with pretreated PTFE. - Abstract: A novel polybenzimidazole (PBI)/poly(tetrafluoroethylene) (PTFE) composite membrane doped with phosphoric acid was fabricated for high temperature operation in a polymer electrolyte membrane (PEM) fuel cell. A hydrophilic surface pretreatment was applied to the porous PTFE matrix film to improve its interfacial adhesion to the PBI polymer, thereby avoiding the introduction of Nafion ionomer which is traditionally used as a coupling agent. The pretreated PTFE film was embedded within the composite membrane during solution-casting using 5wt% PBI/DMAc solution. The mechanical stability and durability of three types of MEAs assembled with PBI only, PBI with pretreated PTFE, and PBI-Nafion with untreated PTFE membranes were evaluated under an accelerated degradation testing protocol employing extreme temperature cycling. Degradation was characterized by recording polarization curves, hydrogen crossover, and proton resistance. Cross-sections of the membranes were examined before and after thermal cycling by scanning electron microscope. Energy-dispersive X-ray spectroscopy verified that the PBI is dispersed homogeneously in the porous PTFE matrix. Results show that the PBI composite membrane with pretreated PTFE has a lower degradation rate than the Nafion/PBI membrane with untreated PTFE. Thus, the hydrophilic pretreatment employed here greatly improved the mechanical stability of the composite membrane, which resulted in improved durability under an extreme thermal cycling regime

  13. Less Than Total Excision of Infected Prosthetic PTFE Graft Does Not Increase the Risk of Reinfection.

    Science.gov (United States)

    Sgroi, Michael D; Kirkpatrick, Vincent E; Resnick, Karen A; Williams, Russell A; Wilson, Samuel E; Gordon, Ian L

    2015-01-01

    Traditional treatment of infected polytetrafluoroethylene (PTFE) grafts consist of removal of the entire prosthesis. Closure of the native vessels may compromise vascular patency. We examined the outcomes for patients in whom a PTFE remnant of an infected graft was retained on the vessel. We reviewed the operating room log from 2000 to 2011 and identified all patients who had partial removal of an infected PTFE graft used for hemodialysis or peripheral bypass. These patients were examined for subsequent complications. Twenty-seven patients underwent 30 partial graft excisions with mean follow-up of 27 months. A total of 17% (5 of 30) of the partial graft resection procedures resulted in complications. Of 48 total remnants left behind at the arterial or venous anastomoses, reinfection occurred in 15%. Leaving a well-incorporated small 1-to 5-mm PTFE remnant at the arterial or venous anastomoses can be performed safely with a low risk of complications. © The Author(s) 2015.

  14. Microfabrication of crosslinked PTFE by synchrotron radiation

    International Nuclear Information System (INIS)

    Sato, Yasunori; Yamaguchi, Daichi; Oshima, Akihiro; Washio, Masakazu; Katoh, Takanori; Aoki, Yasushi; Ikeda, Shigetoshi; Tanaka, Shigeru

    2003-01-01

    Microfabrication of crosslinked polytetrafluoroethylene (PTFE) using synchrotron radiation (SR) has been demonstrated for production of micro-components applicable to radiation fields. The method of microfabrication was readily capable of obtaining a microstructure with aspect-ratio of 25 made of crosslinked PTFE. The etching rate of crosslinked PTFE was higher than that of non-crosslinked PTFE. The results show that the etching rate of crosslinked PTFE depends only on the degree of crosslinking. The effect of molecular motion on etching process was discussed from temperature dependence on etching rate. Moreover, in order to examine whether any change of chemical structures and crystallinity would be induced by SR-irradiation on PTFE, SR-irradiated PTFE was measured by NMR spectroscopy and DSC analysis. The results showed that the crosslinking reaction of PTFE would be induced by SR-irradiation in the solid state. (author)

  15. Radiation grafting of styrene and maleic anhydride onto PTFE membranes and sequent sulfonation for applications of vanadium redox battery

    International Nuclear Information System (INIS)

    Qiu Jingyi; Ni Jiangfeng; Zhai Maolin; Peng Jing; Zhou Henghui; Li Jiuqiang; Wei Genshuan

    2007-01-01

    Using γ-radiation technique, poly(tetrafluoroethylene) (PTFE) membrane was grafted with styrene (St) (PTFE-graft-PS) or binary monomers of St and maleic anhydride (MAn) (PTFE-graft-PS-co-PMAn), respectively. Then grafted membranes were further sulfonated with chlorosulfonic acid into ion-exchange membranes (denoted as PTFE-graft-PSSA and PTFE-graft-PSSA-co-PMAc, respectively) for application of vanadium redox battery (VRB). Micro-FTIR analysis indicated that PTFE was successfully grafted and sulfonated at the above two different conditions. However, a higher degree of grafting (DOG) was obtained in St/MAn binary system at the same dose due to a synergistic effect. Comparing with PTFE-graft-PSSA, PTFE-graft-PSSA-co-PMAc membrane showed higher water uptake and ion-exchange capacity (IEC) and lower area resistance (AR) at the same DOG. In addition, PTFE-graft-PSSA-co-PMAc with 6% DOG also showed a higher IEC and higher conductivity compared to Nafion membrane. Radiation grafting of PTFE in St/MAn binary system and sequent sulfonation is an appropriate method for preparing ion-exchange membrane of VRB

  16. Electrophoretic deposition of PTFE particles on porous anodic aluminum oxide film and its tribological properties

    International Nuclear Information System (INIS)

    Zhang, Dongya; Dong, Guangneng; Chen, Yinjuan; Zeng, Qunfeng

    2014-01-01

    Polytetrafluoroethylene (PTFE) composite film was successfully fabricated by depositing PTFE particles into porous anodic aluminum oxide film using electrophoretic deposition (EPD) process. Firstly, porous anodic aluminum oxide film was synthesized by anodic oxidation process in sulphuric acid electrolyte. Then, PTFE particles in suspension were directionally deposited into the porous substrate. Finally, a heat treatment at 300 °C for 1 h was utilized to enhance PTFE particles adhesion to the substrate. The influence of anodic oxidation parameters on the morphology and micro-hardness of the porous anodic aluminum oxide film was studied and the PTFE particles deposited into the pores were authenticated using energy-dispersive spectrometer (EDS) and scanning electron microscopy (SEM). Tribological properties of the PTFE composite film were investigated under dry sliding. The experimental results showed that the composite film exhibit remarkable low friction. The composite film had friction coefficient of 0.20 which deposited in 15% PTFE emulsion at temperature of 15 °C and current density of 3 A/dm 2 for 35 min. In addition, a control specimen of porous anodic aluminum oxide film and the PTFE composite film were carried out under the same test condition, friction coefficient of the PTFE composite film was reduced by 60% comparing with the control specimen at 380 MPa and 100 mm/s. The lubricating mechanism was that PTFE particles embedded in porous anodic aluminum oxide film smeared a transfer film on the sliding path and the micro-pores could support the supplement of solid lubricant during the sliding, which prolonged the lubrication life of the aluminum alloys.

  17. Chemiluminescence emission from irradiated polytetrafluoroethylene (PTFE)

    International Nuclear Information System (INIS)

    Zhong Xiaoguang; Sun Jiazhen; Yoshii, Fumio; Sasaki, Takashi; Makuuchi, Keizo

    2000-01-01

    PTFE is well known for its chemical and high temperature resistance and also for its high-energy radiation sensitivity. The present work deals with the radiation-induced emission of chemiluminescence from PTFE film, which is generally thought as a measure of radiation induced oxidation reaction in irradiated polymer. The observation that the much stronger chemiluminescence emission from PTFE than that from other polymeric system indicate the unusual high degree of radiation induced oxidation in PTFE. On the other hand the temperature and atmosphere effect during radiation on emission of chemiluminescence were also reported. (author)

  18. Radiation processing for PTFE composite reinforced with carbon fiber

    International Nuclear Information System (INIS)

    Akihiro Oshima; Akira Udagawa; Yousuke Morita

    1999-01-01

    The present work is an attempt to evaluate the performance of crosslinked PTFE as a polymer matrix for carbon fiber-reinforced composite materials. The carbon fiber-reinforced PTFE pre-composite, which is laminated with PTFE fine powder, is crosslinked by electron beam irradiation. Mechanical and frictional properties of the crosslinked PTFE composite obtained are higher than those of PTFE resin. The crosslinked PTFE composite with high mechanical and radiation resistant performance is obtained by radiation crosslinking process

  19. Recycling of PTFE by means of ionizing rays

    International Nuclear Information System (INIS)

    Lee, D.W.

    1994-01-01

    By treatment with beta or gamma rays, PTFE waste is converted to high-grade PTFE fine powder. High-molecular weight PTFE is degraded to low-molecular weight PTFE. Due to this the density, the degree of crystallinity, and the melt flow index are increased, which enhances the brittleness of the material. Irradiation of PTFE thus facilitates milling and makes the material pourable and free-flowing. Milled PTFE fine powder, lie PTFE plastic, combines temperature resistance, weather fastness, and chemical stability with good slip behaviour and antiadhesive properties. Areas of application for fine powder include additives for plastics, printing inks, nonstick coatings, and antifriction lacquers. (orig.) [de

  20. Acid digestion of geological and environmental samples using open-vessel focused microwave digestion.

    Science.gov (United States)

    Taylor, Vivien F; Toms, Andrew; Longerich, Henry P

    2002-01-01

    The application of open vessel focused microwave acid digestion is described for the preparation of geological and environmental samples for analysis using inductively coupled plasma-mass spectrometry (ICP-MS). The method is compared to conventional closed-vessel high pressure methods which are limited in the use of HF to break down silicates. Open-vessel acid digestion more conveniently enables the use of HF to remove Si from geological and plant samples as volatile SiF4, as well as evaporation-to-dryness and sequential acid addition during the procedure. Rock reference materials (G-2 granite, MRG-1 gabbros, SY-2 syenite, JA-1 andesite, and JB-2 and SRM-688 basalts) and plant reference materials (BCR and IAEA lichens, peach leaves, apple leaves, Durham wheat flour, and pine needles) were digested with results comparable to conventional hotplate digestion. The microwave digestion method gave poor results for granitic samples containing refractory minerals, however fusion was the preferred method of preparation for these samples. Sample preparation time was reduced from several days, using conventional hotplate digestion method, to one hour per sample using our microwave method.

  1. Development of a Diehard GEM using PTFE insulator substrate

    OpenAIRE

    Wakabayashi, M.; Komiya, K.; Tamagawa, T.; Takeuchi, Y.; Aoki, K.; Taketani, A.; Hamagaki, H.

    2014-01-01

    We have developed the gas electron multiplier (GEM) using polytetrafluoroethylene (PTFE) insulator substrate (PTFE-GEM). Carbonization on insulator layer by discharges shorts the GEM electrodes, causing permanent breakdown. Since PTFE is hard to be carbonized against arc discharges, PTFE-GEM is expected to be robust against breakdown. Gains as high as 2.6x10^4 were achieved with PTFE-GEM (50 um thick) in Ar/CO2 = 70%/30% gas mixture at V_GEM = 730V. PTFE-GEM never showed a permanent breakdown...

  2. Development of a Diehard GEM using PTFE insulator substrate

    International Nuclear Information System (INIS)

    Wakabayashi, M; Tamagawa, T; Takeuchi, Y; Aoki, K; Taketani, A; Komiya, K; Hamagaki, H

    2014-01-01

    We have developed the gas electron multiplier (GEM) using polytetrafluoroethylene (PTFE) insulator substrate (PTFE-GEM). Carbonization on insulator layer by discharges shorts the GEM electrodes, causing permanent breakdown. Since PTFE is hard to be carbonized against arc discharges, PTFE-GEM is expected to be robust against breakdown. Gains as high as 2.6 × 10 4 were achieved with PTFE-GEM (50 μm thick) in Ar/CO 2 = 70%/30% gas mixture at V GEM = 730 V. PTFE-GEM never showed a permanent breakdown even after suffering more than 40000 times discharges during the experiment. The result demonstrates that PTFE-GEM is really robust against discharges. We conclude that PTFE is an excellent insulator material for the GEM productions

  3. Biomimetic Fluorocarbon Surfactant Polymers Reduce Platelet Adhesion on PTFE/ePTFE Surfaces

    Science.gov (United States)

    Wang, Shuwu; Gupta, Anirban Sen; Sagnella, Sharon; Barendt, Pamela M.; Kottke-Marchant, Kandice; Marchant, Roger E.

    2010-01-01

    We describe a series of fluorocarbon surfactant polymers designed as surface-modifying agents for improving the thrombogenicity of ePTFE vascular graft materials by the reduction of platelet adhesion. The surfactant polymers consist of a poly(vinyl amine) backbone with pendent dextran and perfluoroundecanoyl branches. Surface modification is accomplished by a simple dip-coating process in which surfactant polymers undergo spontaneous surface-induced adsorption and assembly on PTFE/ePTFE surface. The adhesion stability of the surfactant polymer on PTFE was examined under dynamic shear conditions in PBS and human whole blood with a rotating disk system. Fluorocarbon surfactant polymer coatings with three different dextran to perfluorocarbon ratios (1:0.5, 1:1 and 1:2) were compared in the context of platelet adhesion on PTFE/ePTFE surface under dynamic flow conditions. Suppression of platelet adhesion was achieved for all three coated surfaces over the shear-stress range of 0–75 dyn/cm2 in platelet-rich plasma (PRP) or human whole blood. The effectiveness depended on the surfactant polymer composition such that platelet adhesion on coated surfaces decreased significantly with increasing fluorocarbon branch density at 0 dyn/cm2. Our results suggest that fluorocarbon surfactant polymers can effectively suppress platelet adhesion and demonstrate the potential application of the fluorocarbon surfactant polymers as non-thrombogenic coatings for ePTFE vascular grafts. PMID:19323880

  4. Thermal radiation properties of PTFE plasma

    Science.gov (United States)

    Liu, Xiangyang; Wang, Siyu; Zhou, Yang; Wu, Zhiwen; Xie, Kan; Wang, Ningfei

    2017-06-01

    To illuminate the thermal transfer mechanism of devices adopting polytetrafluoroethylene (PTFE) as ablation materials, the thermal radiation properties of PTFE plasma are calculated and discussed based on local thermodynamic equilibrium (LTE) and optical thin assumptions. It is clarified that line radiation is the dominant mechanism of PTFE plasma. The emission coefficient shows an opposite trend for both wavelength regions divided by 550 nm at a temperature above 15 000 K. The emission coefficient increases with increasing temperature and pressure. Furthermore, it has a good log linear relation with pressure. Equivalent emissivity varies complexly with temperature, and has a critical point between 20 000 K to 25 000 K. The equivalent cross points of the average ionic valence and radiation property are about 10 000 K and 15 000 K for fully single ionization.

  5. Catalytic activity of hydrophobic Pt/C/PTFE catalysts of different PTFE content for hydrogen-water liquid exchange reaction

    International Nuclear Information System (INIS)

    Hu Sheng; Xiao Chengjian; Zhu Zuliang; Luo Shunzhong; Wang Heyi; Luo Yangming; Wang Changbin

    2007-01-01

    10%Pt/C catalysts were prepared by liquid reduction method. PTFE and Pt/ C catalysts were adhered to porous metal and hydrophobic Pt/C/PTFE catalysts were prepared. The structure and size of Pt crystal particles of Pt/C catalysts were analyzed by XRD, and their mean size was 3.1 nm. The dispersion state of Pt/C and PTFE was analyzed by SEM, and they had good dispersion mostly, but PTFE membrane could be observed on local parts of Pt/C/PTFE surface. Because of low hydrophobicity, Pt/C/ PTFE catalysts have low activity when the mass ratio of PTFE and Pt/C is 0.5: 1, and their catalytic activity increases markedly when the ratio is 1:1. When the ratio increases again, more Pt active sites would be covered by PTFE and interior diffusion effect would increase, which result in the decrease of catalytic activity of Pt/C/PTFE. By PTFE pretreatment of porous metal carrier, the activity of Pt/C/PTFE catalysts decreases when the mass ratio of PTFE and Pt/C is 0.5:1, and their activity decreases when the mass ratio is 1:1. (authors)

  6. Friction coefficients of PTFE bearing liner

    Science.gov (United States)

    Daniels, C. M.

    1979-01-01

    Data discusses frictional characteristics of PTFE (polytetrafluoroethylene) under temperature extremes and in vacuum environment. Tests were also run on reduced scale hardware to determine effects of vacuum. Data is used as reference by designers of aircraft-control system rod-end bearings and for bearings used in polar regions.

  7. Long-term results of PTFE grafts.

    Science.gov (United States)

    Hedin, Ulf

    2015-01-01

    Vascular surgeons are essential in "lifeline" creation for hemodialysis patients and should be the central player in any multidisciplinary access service together with nephrologists, dialysis staff and interventional radiology. In this position, access surgeons are involved in complicated clinical decision making regarding primary and secondary access selection, which throughout the last decade has been largely aided, and influenced, by national and international guidelines as well as other initiatives. These recommendations, unanimously and appropriately, advocate the placement of native fistulas over synthetic grafts (the majority grafts from expanded polytetrafluoroethylene, ePTFE, herein referred to as PTFE) based on the superiority of fistulas with respect to complications such as infections and thrombosis. Nevertheless, the use of PTFE grafts for hemodialysis access is an accepted and firmly established alternative to native fistulas where data today reveal unwanted consequences to overinterpretation of established guidelines such as increased catheter use. This information highlights a need for an adjustment of access selection strategies based on patient-centered algorithms. Here, available results on PTFE graft performance in hemodialysis access is recapitulated, with respect to both conventional grafts and technical modifications, and conclude with a modified approach to primary access selection.

  8. Mechanisms of Loss of Agricultural Odorous Compounds in Sample Bags of Nalophan, Tedlar, and PTFE.

    Science.gov (United States)

    Kasper, Pernille Lund; Oxbøl, Arne; Hansen, Michael Jørgen; Feilberg, Anders

    2018-03-01

    Alteration of the chemical composition of odor samples during storage in polymer sample bags can significantly impair the accuracy of subsequent odor evaluations. To overcome or minimize this effect, the mechanisms determining compound loss must be more thoroughly understood. The present study examines the storage stability of a selection of key odorants from livestock production in polymer sample bags of Nalophan, Tedlar, and polytetrafluoroethylene (PTFE). The compounds included are acetic acid, butanoic acid, propanoic acid, 3-methylbutanoic acid, hydrogen sulfide, methanethiol, dimethyl sulfide, trimethylamine, and 4-methylphenol. The fate of the unrecovered compound fractions is clarified by means of thermal desorption and concentric double bags, allowing estimation of the magnitude of losses due to adsorption and diffusion, respectively. The degree of recovery was found to be PTFE > Tedlar > Nalophan, and smaller ratios of bag surface area to sample volume improved the recovery significantly. Furthermore, PTFE bags were found far superior for maintaining the original sample humidity and for storing 4-methylphenol. Analysis of sample humidity, partitioning coefficients, and thermal desorption suggested that the loss in PTFE bags was mainly controlled by adsorption, whereas for Nalophan and Tedlar, compound loss is a combined effect of adsorption and diffusion. It is suggested to heat the bags when evacuating the sample for analysis, as this was found to improve the recovery significantly. For a 5-L PTFE bag, all odorants could be found at concentration levels between 71.6 and 98.8% even after 48 h of storage when heated to 57°C prior to analysis. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  9. Constitutive modeling of shock response of PTFE

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Eric N [Los Alamos National Laboratory; Reanyansky, Anatoly D [DSTO, AUSTRALIA; Bourne, Neil K [AWE, UK; Millett, Jeremy C F [AWE, UK

    2009-01-01

    The PTFE (polytetrafluoroethylene) material is complex and attracts attention of the shock physics researchers because it has amorphous and crystalline components. In turn, the crystalline component has four known phases with the high pressure transition to phase III. At the same time, as has been recently studied using spectrometry, the crystalline region is growing with load. Stress and velocity shock-wave profiles acquired recently with embedded gauges demonstrate feature that may be related to impedance mismatches between the regions subjected to some transitions resulting in density and modulus variations. We consider the above mentioned amorphous-to-crystalline transition and the high pressure Phase II-to-III transitions as possible candidates for the analysis. The present work utilizes a multi-phase rate sensitive model to describe shock response of the PTFE material. One-dimensional experimental shock wave profiles are compared with calculated profiles with the kinetics describing the transitions. The objective of this study is to understand the role of the various transitions in the shock response of PTFE.

  10. Method of radiation degradation of PTFE under vacuum conditions

    Energy Technology Data Exchange (ETDEWEB)

    Korenev, Sergey E-mail: sergey_korenev@steris.com

    2004-10-01

    A new method of radiation degradation of Polytetrafluoroethylene (PTFE) under vacuum conditions is considered in this report. The combination of glow gas discharge and electrical surface discharge (on surface and inside PTFE) increases the efficiency of thermal-radiation degradation. The main mechanism of this degradation method consists of the breaking of C-C and C-F bonds. The vacuum conditions allow decreasing of the concentration of toxic compounds, such as a HF. Experimental results for degradation of PTFE are presented.

  11. Method of radiation degradation of PTFE under vacuum conditions

    Science.gov (United States)

    Korenev, Sergey

    2004-09-01

    A new method of radiation degradation of Polytetrafluoroethylene (PTFE) under vacuum conditions is considered in this report. The combination of glow gas discharge and electrical surface discharge (on surface and inside PTFE) increases the efficiency of thermal-radiation degradation. The main mechanism of this degradation method consists of the breaking of C-C and C-F bonds. The vacuum conditions allow decreasing of the concentration of toxic compounds, such as a HF. Experimental results for degradation of PTFE are presented.

  12. Effect of gamma radiation on graphite - PTFE dry lubrication system

    Science.gov (United States)

    Singh, Sachin; Tyagi, Mukti; Seshadri, Geetha; Tyagi, Ajay Kumar; Varshney, Lalit

    2017-12-01

    An effect of gamma radiation on lubrication behavior of graphite -PTFE dry lubrication system has been studied using (TR-TW-30L) tribometer with thrust washer attachment in plane contact. Different compositions of graphite and PTFE were prepared and irradiated by gamma rays. Gamma radiation exposure significantly improves the tribological properties indicated by decrease in coefficient of friction and wear properties of graphite -PTFE dry lubrication system. SEM and XRD analysis confirm the physico-chemical modification of graphite-PTFE on gamma radiation exposure leading to a novel dry lubrication system with good slip and anti friction properties.

  13. Potassium co-transport and antiport during the uptake of sucrose and glutamic acid from the xylem vessels

    NARCIS (Netherlands)

    Bel, A.J.E. van; Erven, A.J. van

    Perfusion experiments with excised internodes of tomato (Lycopersicon esculentum cv Moneymaker) showed that the uptake of glutamic acid and sucrose from the xylem vessels is accompanied with coupled proton co-transport and potassium antiport at low pH (<5.5). At high pH (5.5) both proton and

  14. Study of PTFE wick structure applied to loop heat pipe

    International Nuclear Information System (INIS)

    Wu, Shen-Chun; Gu, Tzu-Wei; Wang, Dawn; Chen, Yau-Ming

    2015-01-01

    This study investigated the use of sintered PTFE (polytetrafluoroethylene) particles as the wick material of loop heat pipe (LHP), taking advantage of PTFE's low thermal conductivity to reduce the heat leakage problem during LHP's operation. Different PTFE particle sizes were tried to find the one that resulted in the best wick; LHP performance tests were then conducted, and PTFE's potential for application to LHP was examined. Using PTFE particles ranging from 300–500 μm in size, the best wick properties were effective pore radius of 1.7 μm, porosity of 50%, and permeability of 6.2 × 10 −12  m 2 . LHP performance tests showed that, under typical electronic devices' operating temperature of 85 °C, the heat load reached 450 W, the thermal resistance was 0.145 °C/W, and the critical heat load (dryout heat load) reached 600 W. Compared to LHP with a nickel wick, LHP with a PTFE wick had a significantly lower operating temperature, indicating reduced heat leakage during operation, while having comparable performance; also, during the manufacturing process, a PTFE wick required lower sintering temperature, needed shorter sintering time, and had no need for hydrogen gas during sintering. The results of this study showed that, for high heat transfer capacity cooling devices, PTFE wicks possess great potential for applications to LHPs. - Highlights: • The performances of PTFE and nickel wicks in LHP are comparable for the first time. • PTFE wick allows for lower operating temperature and thus pressure in LHP system. • A wick requiring lower temperature and manufacturing cost and less time was made. • PTFE wick has potential to replace metal wick and enhance performance of LHP

  15. Dacron or PTFE for above-knee femoropopliteal bypass. a multicenter randomised study

    DEFF Research Database (Denmark)

    Jensen, L P; Lepäntalo, M; Fossdal, J E

    2007-01-01

    To compare polytetrafluorethylene (PTFE) and polyester grafts (Dacron) for above knee femoropopliteal bypass.......To compare polytetrafluorethylene (PTFE) and polyester grafts (Dacron) for above knee femoropopliteal bypass....

  16. ESR study on free radicals trapped in crosslinked polytetrafluoroethylene (PTFE)

    International Nuclear Information System (INIS)

    Oshima, Akihiro; Tabata, Yoneho; Seguchi, Tadao

    1997-01-01

    Free radicals in crosslinked PTFE which formed by 60 Co γ-rays irradiation at 77 K and at room temperature were studied by electron spin resonance (ESR) spectroscopy. The crosslinked PTFE specimens with different crosslinking density were prepared by electron beam irradiation in the molten state. The ESR spectra observed in the irradiated crosslinked PTFE are much different from those in non-crosslinked PTFE (virgin); a broad singlet component increases with increasing the crosslinking density, G-value of radicals is much higher in crosslinked PTFE than in non-crosslinked one. Free radicals related to the broad component are trapped in the non-crystalline region of crosslinked PTFE and rather stable at room temperature, whereas radicals trapped in amorphous non-crosslinked PTFE are unstable at room temperature. It is thought that most of free radicals trapped in the crosslinked PTFE are formed in the crosslinked amorphous region. The trapped radicals decays around 383 K (110 o C) due to the molecular motion of α-relaxation. (Author)

  17. Modification of PTFE nanopowder by controlled electron beam irradiation: A useful approach for the development of PTFE coupled EPDM compounds

    Directory of Open Access Journals (Sweden)

    2008-04-01

    Full Text Available Low-temperature reactive mixing of controlled electron beam modified Polytetrafluoroethylene (PTFE nanopowder with Ethylene-Propylene-Diene-Monomer (EPDM rubber produced PTFE coupled EPDM rubber compounds with desired physical properties. The radiation-induced chemical alterations in PTFE nanopowder, determined by electron spin resonance (ESR and Fourier transform infrared (FTIR spectroscopy, showed increasing concentration of radicals and carboxylic groups (–COOH with increasing irradiation dose. The morphological variations of the PTFE nanopowder including its decreasing mean agglomerate size with the absorbed dose was investigated by particle size and scanning electron microscopy (SEM analysis. With increasing absorbed dose the wettability of the modified PTFE nanopowder determined by contact angle method increased in accordance with the (–COOH concentration. Transmission electron microscopy (TEM showed that modified PTFE nanopowder is obviously enwrapped by EPDM. This leads to a characteristic compatible interphase around the modified PTFE. Crystallization studies by differential scanning calorimetry (DSC also revealed the existence of a compatible interphase in the modified PTFE coupled EPDM.

  18. Studying the Effect of the Concentration of PTFE Nanoparticles on the Tribological Behavior of Ni-P-PTFE Composite Coatings

    Directory of Open Access Journals (Sweden)

    Hamid Rahmati

    2015-10-01

    Full Text Available In the past 30 years, electroless nickel (EN plating has grown to such proportions that these coatings and their applications are now found underground, in outer space, and in a myriad of areas in between. Moreover, in order to further improve the mechanical and tribological properties of the nickel-phosphorous (Ni-P coatings, Ni-P/PTFE composite coatings can be obtained, which provides even greater friction behavior and lubricity than the one naturally occurring in the nickel-phosphorous alloy deposit. In this paper, The Ni-P-PTFE coating was deposited on mild carbon steel surface via electroless deposition process. The friction behavior and wear mechanisms of Ni-P-PTFE nanocomposite coating were studied at different concentrations of PTFE. Frictional behavior was examined using a pin on disk wear test method. Surface morphology and worn surface was evaluated using field emission scanning electron microscopy (FESEM and energy dispersive spectroscopy (EDS analysis. The results showed that the incorporation of PTFE nanoparticles can reduce the wear rate of Ni-P coating from 33.07×10-6 mm3/Nm to 12.46×10-6 mm3/Nm for the Ni-P PTFE containing 10 g/l PTFE and decrease the friction coefficient from 0.64 to 0.2. Thus the tribological behavior of Ni-P coating is much improved in the presence of PTFE nanoparticles and 10 g/l is the optimized concentration of PTFE in the electroless bath.

  19. Layer-by-layer assembly of thin organic films on PTFE activated by cold atmospheric plasma

    Directory of Open Access Journals (Sweden)

    Tóth András

    2014-12-01

    Full Text Available An air diffuse coplanar surface barrier discharge is used to activate the surface of polytetrafluoroethylene (PTFE samples, which are subsequently coated with polyvinylpyrrolidone (PVP and tannic acid (TAN single, bi- and multilayers, respectively, using the dip-coating method. The surfaces are characterized by X-ray Photoelectron Spectroscopy (XPS, Attenuated Total Reflection – Fourier Transform Infrared Spectroscopy (ATR-FTIR and Atomic Force Microscopy (AFM. The XPS measurements show that with plasma treatment the F/C atomic ratio in the PTFE surface decreases, due to the diminution of the concentration of CF2 moieties, and also oxygen incorporation through formation of new C–O, C=O and O=C–O bonds can be observed. In the case of coated samples, the new bonds indicated by XPS show the bonding between the organic layer and the surface, and thus the stability of layers, while the gradual decrease of the concentration of F atoms with the number of deposited layers proves the creation of PVP/TAN bi- and multi-layers. According to the ATR-FTIR spectra, in the case of PVP/TAN multilayer hydrogen bonding develops between the PVP and TAN, which assures the stability of the multilayer. The AFM lateral friction measurements show that the macromolecular layers homogeneously coat the plasma treated PTFE surface.

  20. PTFE-ALUMINUM films serve as neutral density filters

    Science.gov (United States)

    Burks, H. D.

    1966-01-01

    Polytetrafluoroethylene /PTFE/ films coated with aluminum films act as neutral density filters in the wavelength range 0.3 to 2.1 microns. These filters are effective in the calibration of photometric systems.

  1. Degradation and crosslinking of PTFE due to irradiation

    International Nuclear Information System (INIS)

    Tutiya, Mituaki

    1995-01-01

    In this report, we summarized all our experimental results concerning about the effects of Co-60 γ rays irradiation on polytetrafluoroethylene (PTFE). The NMR spectra, the mechanical properties and others of PTFE were measured. The increase in the degree of crystallinity, the lowering of the 19degC transition temperature and that of the melting temperature due to irradiation were observed. The effect of post-irradiation heat treatment were also observed. In each case, the main causes of these effects were attributed to the radiation-induced main chain scission. In the case of PTFE irradiated at 320-360degC in vacuum, we found that the effect of radiation-induced crosslinking were observed. By using our new theories, these experimental results which were measured in the crystalline and the amorphous regions of the irradiated PTFE were discussed, and a satisfactory agreement between the theories and the experiments was obtained. (author)

  2. Impact of lubrication on the tribological behaviour of PTFE ...

    Indian Academy of Sciences (India)

    bronze and bronze + molybdenum disulfide (MoS2) were considered. These composites were ... the PTFE composites have significantly been reduced in the lubricated condition ... there are no strong bonds between the fillers and the matrix in.

  3. Polyester composite versus PTFE in laparoscopic ventral hernia repair.

    Science.gov (United States)

    Colon, Modesto J; Telem, Dana A; Chin, Edward; Weber, Kaare; Divino, Celia M; Nguyen, Scott Q

    2011-01-01

    Both polyester composite (POC) and polytetrafluoroethylene (PTFE) mesh are commonly used for laparoscopic ventral hernia repair. However, sparse information exists comparing perioperative and long-term outcome by mesh repair. A prospective database was utilized to identify 116 consecutive patients who underwent laparoscopic ventral hernia repair at The Mount Sinai Hospital from 2004-2009. Patients were grouped by type of mesh used, PTFE versus POC, and retrospectively compared. Follow-up at a mean of 12 months was achieved by telephone interview and office visit. Of the 116 patients, 66 underwent ventral hernia repair with PTFE and 50 with POC mesh. Patients were well matched by patient demographics. No difference in mean body mass index (BMI) was demonstrated between the PTFE and POC group (31.8 vs. 32.5, respectively; P=NS). Operative time was significantly longer in the PTFE group (136 vs.106 minutes, PPTFE group and none in the POC group (P NS). No other major complications occurred in the immediate postoperative period (30 days). At a mean follow-up of 12 months, no significant difference was demonstrated between the PTFE and POC groups in hernia recurrence (3% vs. 2%), wound complications (1% vs. 0%), mesh infection, requiring removal (3% vs. 0%), bowel obstruction (3% vs. 2%), or persistent pain or discomfort (28% vs. 32%), respectively (P=NS). Our study demonstrated no significant association between types of mesh used and postoperative complications. In the 12-month follow-up, no differences were noted in hernia recurrence.

  4. Magnetorheological fluid based on thixotropic PTFE-oil organogel

    Science.gov (United States)

    Zhang, Hansong; Yan, Hua; Hu, Zhide; Yang, Jianjian; Niu, Fanghao

    2018-04-01

    Polytetrafluoroethylene (PTFE) micropowders were employed in this work to fabricate PTFE-oil organogel, then carbonyl iron particles were dispersed in this thixotropic organogel to prepare magnetorheological fluids without any other additives. By performing a comparative investigation of MRFs' performances, enhanced magnetorheological response, suspension stability and tribological performance were obtained contrast to pure silicon oil based MRFs. The experimental results revealed a changeable viscosity of organogel, considerable increases in thixotropy also can be observed with the increase of PTFE content. Sedimentation tests demonstrated a much better suspension stability of MRFs based on organogel, suggesting that the internal network microstructures formed by hydrogen bonds between PTFE microparticles and oil molecular chains are likely to impose the gaps among magnetic particles thus hinder the particle aggregation and sedimentation. Moreover, a critical PTFE volume fraction about 4.7 vol% was recognized in this study, lower content organogels tended to display enhanced yield stresses contrast to pure silicon oil based MRFs while high content organogels showed slightly lower ones. It may suggest a compromise between nonmagnetic particle adsorption and the reinforcement effect of network microstructures. The adsorption is likely to decrease the saturation magnetization of carbonyl iron particles and to hinder the formation of field-induced chains, however, the reinforcement effect tends to strengthen these magnetic chains. Besides, the tribological tests confirmed the lubricant effects of PTFE-oil organogel by acquiring rather sharp decreases in friction coefficients of organogel based MRFs especially in the presence of magnetic field.

  5. Improved patency and reduced intimal hyperplasia in PTFE grafts with luminal immobilized heparin compared with standard PTFE grafts at six months in a sheep model.

    Science.gov (United States)

    Pedersen, G; Laxdal, E; Ellensen, V; Jonung, T; Mattsson, E

    2010-06-01

    The aim of this study was to compare the performance of polytetrafluoroethylene (PTFE) grafts with luminal coating of immobilized heparin to that of standard PTFE grafts at six months. Twenty-eight common carotid arteries in fourteen sheep were bypassed with heparin-coated PTFE grafts (6 mm diameter, 6 cm length) on one side and standard PTFE grafts on the other. The grafts were explanted after six months. The thickness of intimal hyperplasia (IH) in open grafts was measured with histomorphometrical methods. Two of 14 heparinized PTFE grafts and nine of 14 grafts in the control PTFE-group were occluded at explantation (P=0.006). Six-month patency rates for heparinized PTFE grafts and for standard PTFE grafts were 86% and 36%, respectively. Mean graft anastomotic IH thickness in open grafts were 0.074 mm for heparinized PTFE grafts and 0.259 mm for PTFE-grafts (P=0.006). PTFE grafts with luminal coating containing immobilized heparin had significantly better patency and recruited less intimal hyperplasia than standard PTFE grafts at six months.

  6. The Scandinavian Propaten(®) trial - 1-year patency of PTFE vascular prostheses with heparin-bonded luminal surfaces compared to ordinary pure PTFE vascular prostheses - a randomised clinical controlled multi-centre trial

    DEFF Research Database (Denmark)

    Lindholt, J S; Gottschalksen, B; Johannesen, N

    2011-01-01

    To compare 1-year potencies' of heparin-bonded PTFE [(Hb-PTFE) (Propaten(®))] grafts with those of ordinary polytetraflouroethylene (PTFE) grafts in a blinded, randomised, clinically controlled, multi-centre study.......To compare 1-year potencies' of heparin-bonded PTFE [(Hb-PTFE) (Propaten(®))] grafts with those of ordinary polytetraflouroethylene (PTFE) grafts in a blinded, randomised, clinically controlled, multi-centre study....

  7. Sulfonation of cPTFE Film grafted Styrene for Proton Exchange Membrane Fuel Cell

    Directory of Open Access Journals (Sweden)

    Yohan Yohan

    2010-10-01

    Full Text Available Sulfonation of γ-ray iradiated and styrene-grafted crosslinked polytetrafluoroethylene film (cPTFE-g-S film have been done. The aim of the research is to make hydropyl membrane as proton exchange membrane fuel cell. Sulfonation was prepared with chlorosulfonic acid in chloroethane under various conditions. The impact of the percent of grafting, the concentration of chlorosulfonic acid, the reaction time,and the reaction temperature on the properties of sulfonated film is examinated. The results show that sulfonation of surface-grafted films is incomplete at room  temperature. The increasing of concentration of chlorosulfonic acid and reaction temperature accelerates the reaction but they also add favor side reactions. These will lead to decreasing of the ion-exchange capacity, water uptake, and proton conductivity but increasing the resistance to oxidation in a perhidrol solution. The cPTFE-g-SS membrane which is resulted has stability in a H2O2 30% solution for 20 hours.

  8. Thermal desorption study of physical forces at the PTFE surface

    Science.gov (United States)

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

    1987-01-01

    Thermal desorption spectroscopy (TDS) of the polytetrafluoroethylene (PTFE) surface was successfully employed to study the possible role of physical forces in the enhancement of metal-PTFE adhesion by radiation. The thermal desorption spectra were analyzed without assumptions to yield the activation energy for desorption over a range of xenon coverage from less than 0.1 monolayer to more than 100 monolayers. For multilayer coverage, the desorption is zero-order with an activation energy equal to the sublimation energy of xenon. For submonolayer coverages, the order for desorption from the unirradiated PTFE surface is 0.73 and the activation energy for desorption is between 3.32 and 3.36 kcal/mol; less than the xenon sublimation energy. The effect of irradiation is to increase the activation energy for desorption to as high as 4 kcal/mol at low coverage.

  9. Coupling sequential injection on-line preconcentration using a PTFE beads packed column to direct injection nebulization inductively coupled plasma mass spectrometry

    DEFF Research Database (Denmark)

    Wang, Jianhua; Hansen, Elo Harald

    2002-01-01

    An automated sequential injection on-line preconcentration procedure for trace metals by using a PTFE bead-packed microcolumn coupled to ICP-MS is described, and used for simultaneous analyses of cadmium and lead. In dilute nitric acid (0.5%, v/v), neutral complexes between the analytes...

  10. Tailoring Novel PTFE Surface Properties: Promoting Cell Adhesion and Antifouling Properties via a Wet Chemical Approach.

    Science.gov (United States)

    Gabriel, Matthias; Niederer, Kerstin; Becker, Marc; Raynaud, Christophe Michel; Vahl, Christian-Friedrich; Frey, Holger

    2016-05-18

    Many biomaterials used for tissue engineering applications lack cell-adhesiveness and, in addition, are prone to nonspecific adsorption of proteins. This is especially important for blood-contacting devices such as vascular grafts and valves where appropriate surface properties should inhibit the initial attachment of platelets and promote endothelial cell colonization. As a consequence, the long-term outcome of the implants would be improved and the need for anticoagulation therapy could be reduced or even abolished. Polytetrafluoroethylene (PTFE), a frequently used polymer for various medical applications, was wet-chemically activated and subsequently modified by grafting the endothelial cell (EC) specific peptide arginine-glutamic acid-aspartic acid-valine (REDV) using a bifunctional polyethylene glycol (PEG)-spacer (known to reduce platelet and nonspecific protein adhesion). Modified and control surfaces were both evaluated in terms of EC adhesion, colonization, and the attachment of platelets. In addition, samples underwent bacterial challenges. The results strongly suggested that PEG-mediated peptide immobilization renders PTFE an excellent substrate for cellular growth while simultaneously endowing the material with antifouling properties.

  11. Pt-Fe catalyst nanoparticles supported on single-wall carbon nanotubes: Direct synthesis and electrochemical performance for methanol oxidation

    Science.gov (United States)

    Ma, Xiaohui; Luo, Liqiang; Zhu, Limei; Yu, Liming; Sheng, Leimei; An, Kang; Ando, Yoshinori; Zhao, Xinluo

    2013-11-01

    Single-wall carbon nanotubes (SWCNTs) supported Pt-Fe nanoparticles have been prepared by one-step hydrogen arc discharge evaporation of carbon electrode containing both Pt and Fe metal elements. The formation of SWCNTs and Pt-Fe nanoparticles occur simultaneously during the evaporation process. High-temperature hydrogen treatment and hydrochloric acid soaking have been carried out to purify and activate those materials in order to obtain a new type of Pt-Fe/SWCNTs catalyst for methanol oxidation. The Pt-Fe/SWCNTs catalyst performs much higher electrocatalytic activity for methanol oxidation, better stability and better durability than a commercial Pt/C catalyst according to the electrochemical measurements, indicating that it has a great potential for applications in direct methanol fuel cells.

  12. Dosimetric properties of LIF:Mg,CuP+PTFE

    International Nuclear Information System (INIS)

    Gonzalez Martinez, P.R.; Azorin Nieto, J.; Ramirez Luna, A.

    1998-01-01

    The work presents the preparation method, as well as the characterization of the dosemeters of LiF;Mg,Cu+PTFE developed in the National Institute of Nuclear Investigations (ININ) Mexico, Among the carried out tests can mention, sensibility, detection threshold, equivalent of bottom, uniformity, reproducibility, dissipation, answer in function of the dose and kinetic parameters

  13. Creation and Validation of Sintered PTFE BRDF Targets & Standards.

    Science.gov (United States)

    Durell, Christopher; Scharpf, Dan; McKee, Greg; L'Heureux, Michelle; Georgiev, Georgi; Obein, Gael; Cooksey, Catherine

    2015-09-21

    Sintered polytetrafluoroethylene (PTFE) is an extremely stable, near-perfect Lambertian reflecting diffuser and calibration standard material that has been used by national labs, space, aerospace and commercial sectors for over two decades. New uncertainty targets of 2 % on-orbit absolute validation in the Earth Observing Systems community have challenged the industry to improve is characterization and knowledge of almost every aspect of radiometric performance (space and ground). Assuming "near perfect" reflectance for angular dependent measurements is no longer going to suffice for many program needs. The total hemispherical spectral reflectance provides a good mark of general performance; but, without the angular characterization of bidirectional reflectance distribution function (BRDF) measurements, critical data is missing from many applications and uncertainty budgets. Therefore, traceable BRDF measurement capability is needed to characterize sintered PTFE's angular response and provide a full uncertainty profile to users. This paper presents preliminary comparison measurements of the BRDF of sintered PTFE from several laboratories to better quantify the BRDF of sintered PTFE, assess the BRDF measurement comparability between laboratories, and improve estimates of measurement uncertainties under laboratory conditions.

  14. Peroxi-coagulation degradation of C.I. Basic Yellow 2 based on carbon-PTFE and carbon nanotube-PTFE electrodes as cathode

    International Nuclear Information System (INIS)

    Zarei, Mahmoud; Salari, Darioush; Niaei, Aligoli; Khataee, Alireza

    2009-01-01

    The electrochemical treatment of solutions containing C.I. Basic Yellow 2 (BY2) in aqueous solutions with carbon-PTFE (polytetrafluoroethylene) and carbon nanotube (CNT)-PTFE electrodes as cathode has been studied. The fabricated electrodes were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The amount of electrogenerated H 2 O 2 on the surface of these electrodes was investigated, too. The results showed that the amount of H 2 O 2 obtained with the CNT-PTFE electrode was nearly three times higher than that of carbon-PTFE electrode. The decolorization efficiency of BY2 in peroxi-coagulation process reached 62% and 96% in the first 10 min by carbon-PTFE and CNT-PTFE electrodes at 100 mA, respectively. The effect of operational parameters such as applied current, initial pH and initial dye concentration was studied in an attempt to reach higher decolorization efficiency. The degradation and mineralization of BY2 using CNT-PTFE electrode were followed by total organic carbon (TOC) and GC-MS analysis. The results of TOC measurements indicated that peroxi-coagulation with carbon-PTFE allowed 81% mineralization after 6 h of electrolysis; whereas peroxi-coagulation with CNT-PTFE yields 92% mineralization under the same conditions. GC-MS analysis verified the identity of intermediates and a reaction pathway based on them was proposed.

  15. 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.

  16. Vessel Operating Units (Vessels)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains data for vessels that are greater than five net tons and have a current US Coast Guard documentation number. Beginning in1979, the NMFS...

  17. Nitrogen and Fluorine co-doped carbon catalyst with high oxygen reduction performance, prepared by pyrolyzing a mixture of melamine and PTFE

    International Nuclear Information System (INIS)

    Peng, Hongliang; Liu, Fangfang; Qiao, Xiaochang; Xiong, Ziang; Li, Xiuhua; Shu, Ting; Liao, Shijun

    2015-01-01

    Graphical abstract: A novel N and F co-doped metal-free doped carbon catalyst with three dimensional vesicles structures and ultra thin walls are prepared by pyrolyzing the mixture of melamine and PTFE. The catalyst has high N and F contents (13 and 6 at.%), and exhibits high ORR activity, high stability, and high limitation current density in both alkaline and acid medium. - Highlights: • N and F co-doped carbon catalyst was derived from the mixture of PTFE and melamine. • The N and F contents of the catalyst are up to 13 and 6 at.%, respectively. • The catalyst has three dimensional vesicles structure with ultra thin walls. • ORR activity of the catalyst is superior to that of Pt/C catalyst in alkaline medium. - Abstract: A novel nitrogen and fluorine co-doped carbon catalyst (C-Mela-PTFE) is prepared by pyrolyzing a mixture of melamine and polytetrafluoroethylene (PTFE), the catalyst has a three-dimensional vesicular structure with ultrathin wall, and exhibits excellent ORR performance in both alkaline and acidic mediums. In an alkaline medium, the catalyst exhibits superior ORR activity to that of commercial Pt/C catalyst. Notably, the ORR activity of the catalyst is just slightly lower than that of Pt/C catalyst in acidic medium. It is interesting that the ORR limiting current density of our C-Mela-PTFE catalyst is much higher than that of Pt/C catalyst. The effects of the melamine/PTFE ratio and the pyrolysis temperature on the catalyst's ORR performance are investigated. The optimal melamine/PTFE ratio by weight is 1:1.5, and the optimal pyrolysis temperature is 950 °C. The catalyst samples are characterized by XRD, SEM/TEM, Raman analysis, and XPS, the results reveal the ultra-thin-walled vesicular structure, high surface area and porosity, and high doping amounts of N and F of the catalyst. For the optimal sample, the N and F contents are up to 13 and 6 at.%, respectively, the proportion of pyridinic N is up to 45 at.% according to the

  18. Pressurized wet digestion in open vessels (T11)

    International Nuclear Information System (INIS)

    Kettisch, P.; Maichin, P.; Zischka, M.; Knapp, G.

    2002-01-01

    Full text: Pressurized wet digestion in closed vessels, microwave assisted or with conventional conductive heating, is the most important sample preparation technique for digestion or leaching procedures in element analysis. In comparison to open vessel digestion closed vessel digestion methods have many advantages, but there is one disadvantage - complex and expensive vessel designs. A new technique - pressurized wet digestion in open vessels - combine the advantages of closed vessel sample digestion with the application of simple and cheap open vessels made of quartz or PFA. The vessels are placed in a high pressure Asher HPA, which is adapted with a Teflon liner and filled partly with water. The analytical results with 30 ml quartz vessels, 22 ml PFA vessels and 1.5 ml PIA auto sampler cups will be shown. In principle every dimensions of vessels can be used. The vessels are loaded with sample material (max. 1.5 g with quartz vessels, max. 0.5 g with PFA vessels and 50 mg with auto sampler cups) and digestion reagent. Afterwards the vessels are simply covered with PTFE stoppers and not sealed. The vessels are transferred into a special adapted HPA and digested at temperatures up to 270 o C. The digestion time is 90 min. and cooling down to room temperature 30 min. The analytical results of CRM's are within the certified values and no cross contamination and losses of volatile elements could be observed. (author)

  19. Dosimetric characterization of KMgF3:Tb+PTFE

    International Nuclear Information System (INIS)

    Ramirez R, M. I.; Garcia S, L.; Villicana M, M.; Huirache A, R.; Apolinar C, J.; Gonzalez M, P. R.

    2017-10-01

    In this work the results obtained from the dosimetric characterization of the new radiation detectors of KMgF 3 :Tb+PTFE are presented. The host salt was obtained by means of the microwave technique, with the polycrystalline powder obtained, dosimeters were made in tablet form, using as Ptfe binder. The thermoluminescent response of these new detectors presented a linear behavior, in the dose range between 1 and 1000 Gy of 60 Co gamma radiation, the reproducibility test in the measurements, during ten cycles of heat treatment, irradiation and reading presented ± 3.7% Ds, in the stability test of thermoluminescent signal, during two months showed that the fading is practically null. Due to the results obtained, this new detector could be very useful for the dosimetry of ionizing radiation in different clinical applications. (Author)

  20. Robust Non-Wetting PTFE Surfaces by Femtosecond Laser Machining

    Directory of Open Access Journals (Sweden)

    Fang Liang

    2014-08-01

    Full Text Available Nature shows many examples of surfaces with extraordinary wettability, which can often be associated with particular air-trapping surface patterns. Here, robust non-wetting surfaces have been created by femtosecond laser ablation of polytetrafluoroethylene (PTFE. The laser-created surface structure resembles a forest of entangled fibers, which support structural superhydrophobicity even when the surface chemistry is changed by gold coating. SEM analysis showed that the degree of entanglement of hairs and the depth of the forest pattern correlates positively with accumulated laser fluence and can thus be influenced by altering various laser process parameters. The resulting fibrous surfaces exhibit a tremendous decrease in wettability compared to smooth PTFE surfaces; droplets impacting the virgin or gold coated PTFE forest do not wet the surface but bounce off. Exploratory bioadhesion experiments showed that the surfaces are truly air-trapping and do not support cell adhesion. Therewith, the created surfaces successfully mimic biological surfaces such as insect wings with robust anti-wetting behavior and potential for antiadhesive applications. In addition, the fabrication can be carried out in one process step, and our results clearly show the insensitivity of the resulting non-wetting behavior to variations in the process parameters, both of which make it a strong candidate for industrial applications.

  1. Tribological study of PTFE composites loaded with porcelain tile waste

    International Nuclear Information System (INIS)

    Oliveira, P.M.; Araujo Neto, A.P.; Souza, J.R.; Medeiros, J.T.N.

    2016-01-01

    The Brazilian northeast is one of the largest producers of clays that burn in the white form and disposal of tailings from the process of polishing the ceramic pieces of porcelain stands out as a major source of environmental degradation. This problem can be reduced by adding such material as filler in composites, in order to improve the mechanical properties of the polymeric matrix. Polytetrafluoroethylene (PTFE) is characterized as a good solid lubricant, because it has excellent properties such as low coefficient of friction (0.01 < μ < 0.1), thermal stability at high temperatures and chemical resistance. However, the pure PTFE has high wear rates (greater than 10-13m2/N) leading to early failures of various components. To reuse the Tailings of Porcelain (TP), composites of PTFE + TP were developed in three different compositions (85:15, 75:25 and 65:35). For this investigation the particle size distribution and some chemical characteristics of the tailings by testing XRD, XRF, SEM and EDS were performed, registering a large amount of silica, aluminum and other metals. Roughness, wettability and sclerometry also were performed. It was noted that the values of arithmetic average roughness, Ra, is higher for composites with higher percentage of TP, in addition they have a lower contact angle and higher surface energy to distilled water, characterized as hydrophilic. The results of energy of deformation provided by the sclerometry test were non-linear. (author)

  2. 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.

  3. Robust non-wetting PTFE surfaces by femtosecond laser machining.

    Science.gov (United States)

    Liang, Fang; Lehr, Jorge; Danielczak, Lisa; Leask, Richard; Kietzig, Anne-Marie

    2014-08-08

    Nature shows many examples of surfaces with extraordinary wettability,which can often be associated with particular air-trapping surface patterns. Here,robust non-wetting surfaces have been created by femtosecond laser ablation of polytetrafluoroethylene (PTFE). The laser-created surface structure resembles a forest of entangled fibers, which support structural superhydrophobicity even when the surface chemistry is changed by gold coating. SEM analysis showed that the degree of entanglement of hairs and the depth of the forest pattern correlates positively with accumulated laser fluence and can thus be influenced by altering various laser process parameters. The resulting fibrous surfaces exhibit a tremendous decrease in wettability compared to smooth PTFE surfaces; droplets impacting the virgin or gold coated PTFE forest do not wet the surface but bounce off. Exploratory bioadhesion experiments showed that the surfaces are truly air-trapping and do not support cell adhesion. Therewith, the created surfaces successfully mimic biological surfaces such as insect wings with robust anti-wetting behavior and potential for antiadhesive applications. In addition, the fabrication can be carried out in one process step, and our results clearly show the insensitivity of the resulting non-wetting behavior to variations in the process parameters,both of which make it a strong candidate for industrial applications.

  4. Wear resistant PTFE thin film enabled by a polydopamine adhesive layer

    International Nuclear Information System (INIS)

    Beckford, Samuel; Zou, Min

    2014-01-01

    The influence of a polydopamine (PDA) adhesive layer on the friction and wear resistance of polytetrafluoroethylene (PTFE) thin films coated on stainless steel was investigated. The friction and wear tests were carried out using a ball on flat configuration under a normal load of 50 g, sliding speed of 2.5 mm/s, and stroke length of 15 mm. It is found that the PDA/PTFE film is able to withstand approximately 500 times more rubbing cycles than the PTFE film alone. X-ray photoelectron spectroscopy (XPS) results show that a tenacious layer of PTFE remains adhered to the PDA layer, which enables the durability of the PDA/PTFE film. Because of the relatively low thickness of the film, PDA/PTFE shows great potential for use in applications where durable, thin films are desirable

  5. Study on poly-electrolyte membrane of crosslinked PTFE by radiation-grafting

    International Nuclear Information System (INIS)

    Sato, Kohei; Ikeda, Shigetoshi; Iida, Minoru; Oshima, Akihiro; Tabata, Yoneho; Washio, Masakazu

    2003-01-01

    Polymer electrolyte fuel cell membrane based on crosslinked polytetrafluoroethylene (PTFE) [RX-PTFE] has been processed by radiation-grafting with reactive styrene monomers by γ-rays under atmospheric circumstances, and the characteristic properties of the obtained membranes have been studied. The grafting yields of styrene monomer onto RX-PTFE, which have various crosslinking densities, were in the range of 5-100%. At the reaction period of 24 h, the grafting yields for RX-PTFE with low crosslinking density, which was reacted at 60 deg. C, achieved 94%. As a tendency, the lower grafting temperature gives higher grafting ratio of styrene onto RX-PTFE. Moreover, the yields of subsequent sulfonation for all samples were close to 100%. Mechanical properties were decreased with increasing grafting yields; especially the membrane with higher grafting yields was brittle. Ion exchange capacity of sulfonated RX-PTFE reached 1.1 meq/g while maintaining the mechanical properties

  6. Surface modification of PTFE sheet by synchrotron radiation in the soft X-ray region

    International Nuclear Information System (INIS)

    Kato, Y.; Kanda, K.; Haruyama, Y.; Matsui, S.

    2004-01-01

    Full text: The surface properties of poly (tetrafluoroethylene) (PTFE) are changed by the exposure to synchrotron radiation (SR). We succeeded in controlling the wettability of the PTFE surface from hydrophobic to hydrophilic by varying the substrate temperature during the SR irradiation and found that the wettability was ascribable to microstructure and chemical composition of surface.In these previous works, oxygen atoms were found to inhabit on the hydrophobic surface of PTFE. In this study, we investigated the surface modification of PTFE from the SR exposure experiment under the O 2 gas atmosphere. The SR exposure to the PTFE sheet was carried out at beamline 6 (BL6) of the New- SUBARU. The PTFE sheet was irradiated to the white beam, ranging 50-1000 eV at BL6 at room temperature. The gas cell was mounted at the irradiation chamber. The O 2 gas pressure in the gas cell can be maintained at about 0.20 Pa during the SR exposure using 5mm φ hole window. The wettability of PTFE surface was evaluated by the contact angle of a small water drop. Contact angle was measured with the water drop of 1 μl using the contact angle meter. Fig.1 shows the SR dose dependence of contact angle of PTFE surface under the O 2 gas atmosphere and under the vacuum. Contact angle decreased monotonically with SR dose. The decrease rate of contact angle of the PTFE surface irradiated under the O 2 gas atmosphere was larger than that of the PTFE surface irradiated without O 2 gas. Therefore, the combination of O atom to the PTFE surface was enhanced by the O 2 gas in the reaction region. These results suggested that the bonding of O atom on the hydrophobic PTFE surface is dominantly produced in the sample chamber during SR irradiation, but not in the air atmosphere after the SR irradiation

  7. Pressurized Vessel Slurry Pumping

    International Nuclear Information System (INIS)

    Pound, C.R.

    2001-01-01

    This report summarizes testing of an alternate ''pressurized vessel slurry pumping'' apparatus. The principle is similar to rural domestic water systems and ''acid eggs'' used in chemical laboratories in that material is extruded by displacement with compressed air

  8. 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.

  9. Nano-structuring of PTFE surface by plasma treatment, etching, and sputtering with gold

    International Nuclear Information System (INIS)

    Reznickova, Alena; Kolska, Zdenka; Hnatowicz, Vladimir; Svorcik, Vaclav

    2011-01-01

    Properties of pristine, plasma modified, and etched (by water and methanol) polytetrafluoroethylene (PTFE) were studied. Gold nanolayers sputtered on this modified PTFE have been also investigated. Contact angle, measured by goniometry, was studied as a function of plasma exposure and post-exposure aging times. Degradation of polymer chains was examined by etching of plasma modified PTFE in water or methanol. The amount of ablated and etched layer was measured by gravimetry. In the next step the pristine, plasma modified, and etched PTFE was sputtered with gold. Changes in surface morphology were observed using atomic force microscopy. Chemical structure of modified polymers was characterized by X-ray photoelectron spectroscopy (XPS). Surface chemistry of the samples was investigated by electrokinetic analysis. Sheet resistance of the gold layers was measured by two-point technique. The contact angle of the plasma modified PTFE decreases with increasing exposure time. The PTFE amount, ablated by the plasma treatment, increases with the plasma exposure time. XPS measurements proved that during the plasma treatment the PTFE macromolecular chains are degraded and oxidized and new –C–O–C–, –C=O, and –O–C=O groups are created in modified surface layer. Surface of the plasma modified PTFE is weakly soluble in methanol and intensively soluble in water. Zeta potential and XPS shown dramatic changes in PTFE surface chemistry after the plasma exposure, water etching, and gold deposition. When continuous gold layer is formed a rapid decrease of the sheet resistance of the gold layer is observed.

  10. Improved conductivity of carbon-nano-fiber (CNF)/polytetrafluoroethylene (PTFE) composite

    Energy Technology Data Exchange (ETDEWEB)

    Chandra, Sarita; Kalra, G. S.; Pushkar, Vinay K.; Gill, Fateh Singh, E-mail: drfatehs@gmail.com [Graphic Era University, Bell Road, Clement Town, Dehradun (India); Panwar, Variz [School of Materials Science and Engineering, Gwangju Institute of Science Technology (GIST), Gwangju 500-712 (Korea, Republic of); Gupta, Himanshu; Pal, Pankaj K.; Pathak, Trilok K.; Purohit, L. P. [Gurukul Kangri University, Haridwar-249404 (India)

    2016-05-23

    A series of CNF/PTFE composite loaded with different weight % of CNFs as 0.01, 0.02, 0.03, 0.05, 1, 2, 3, 4, 5 into PTFE is fabricated. In this work, the 5wt% heat-treated CNFs were used as filler in PTFE. Current-voltage (I-V) study of the samples confirmed the samples as conducting composite. In scanning electron microscope (SEM) study, the conducting CNFs channels were observed from upper surface to inside throughout the polymer matrix. A sintered composite of 5 wt% loading of CNFs showed an improved conductivity and SEM image exhibited a good binding of CNFs into PTFE.

  11. Improved conductivity of carbon-nano-fiber (CNF)/polytetrafluoroethylene (PTFE) composite

    International Nuclear Information System (INIS)

    Chandra, Sarita; Kalra, G. S.; Pushkar, Vinay K.; Gill, Fateh Singh; Panwar, Variz; Gupta, Himanshu; Pal, Pankaj K.; Pathak, Trilok K.; Purohit, L. P.

    2016-01-01

    A series of CNF/PTFE composite loaded with different weight % of CNFs as 0.01, 0.02, 0.03, 0.05, 1, 2, 3, 4, 5 into PTFE is fabricated. In this work, the 5wt% heat-treated CNFs were used as filler in PTFE. Current-voltage (I-V) study of the samples confirmed the samples as conducting composite. In scanning electron microscope (SEM) study, the conducting CNFs channels were observed from upper surface to inside throughout the polymer matrix. A sintered composite of 5 wt% loading of CNFs showed an improved conductivity and SEM image exhibited a good binding of CNFs into PTFE.

  12. Performance of in-vessel composting of food waste in the presence of coal ash and uric acid

    International Nuclear Information System (INIS)

    An, Chun-Jiang; Huang, Guo-He; Yao, Yao; Sun, Wei; An, Kai

    2012-01-01

    Highlights: ► The amendments of CA and UA could facilitate the composting performance. ► The overall performance is a sum of different events with different mechanisms. ► The added CA and UA might lead to higher pH during the composting. ► The process is correlated with the variations of microbial activity and C/N ratio. ► The presence of CA and UA has significant influence on composting of food waste. - Abstract: Massive quantities of food waste often coexist with other agroindustrial and industrial waste, which might contain coal ash (CA) and uric acid (UA). This study investigated the influence of CA and UA on the composting of food waste in the in-vessel system. The patterns of food waste composting were compared among various combinations. The results showed that the temperature level was enhanced in the presence of CA and UA during the first 8 days. The significant drop in pH was observed in the treatment without any amendment. But the presence of CA could alleviate the drop of pH. More intensive organic mass reduction took place in the treatments with amended CA and UA in the first half of process. The O 2 uptake rate in the reactor with CA and UA was higher than that with only CA in the early stage. Both thermophilic and mesophilic microorganisms were present throughout the composting period. The populations of both thermophilic and mesophilic microorganisms were influenced when amended with CA and UA. The decreasing trend in C/N ratio was shown in all the reactors, while a relatively lower C/N ratio was obtained in the series with both CA and UA.

  13. A Novel Non-Planar Transverse Stretching Process for Micro-Porous PTFE Membranes and Resulting Characteristics

    KAUST Repository

    Chang, Y.-H.; Chen, S.-C.; Wang, T.-J.; Guo, J.

    2018-01-01

    Polytetrafluoroethylene (PTFE) micro-porous membranes were prepared from PTFE fine powder through extruding, rolling, and uniaxial longitudinally stretching. In contrast to conventional planar transverse stretching, a novel 3D mold design of non

  14. Low-Flammability PTFE for High-Oxygen Environments

    Science.gov (United States)

    Walle, E.; Fallon, B.; Sheppard, A.

    1986-01-01

    Modified forming process removes volatile combustible materials. Flammability of cable-wrapping tape reduced by altering tape-manufacturing process. In new manufacturing process, tape formed by proprietary process of screw extrusion, followed by washing in solvent and drying. Tape then wrapped as before. Spectrogram taken after extrusion, washing, and drying shows lower hydrocarbon content. PTFE formed by new process suited to oxygen-rich environments. Safe in liquid oxygen of Space Shuttle tank and in medical uses; thin-wall shrinkable tubing in hospital test equipment, surgical instruments, and implants.

  15. Immobilisation of a fibrillin-1 fragment enhances the biocompatibility of PTFE.

    Science.gov (United States)

    Hajian, Hamid; Wise, Steven G; Bax, Daniel V; Kondyurin, Alexey; Waterhouse, Anna; Dunn, Louise L; Kielty, Cay M; Yu, Young; Weiss, Anthony S; Bilek, Marcela M M; Bannon, Paul G; Ng, Martin K C

    2014-04-01

    Current vascular biomaterials exhibit poor biocompatibility characterised by failure to promote endothelialisation, predisposition to neoinitmal hyperplasia and excessive thrombogenicity. Fibrillin-1, a major constituent of microfibrils is associated with elastic fibres in the arterial wall. Fibrillin-1 binds to endothelial cells through an RGD cell adhesion motif in the fourth TB module. The RGD motif is present in PF8, a recombinant fibrillin-1 fragment. We investigated the potential of PF8 to improve the biocompatibility of PTFE. PF8 enhanced endothelial cell attachment and cell proliferation to a greater extent than fibronectin (pPTFE using plasma immersion ion implantation (PIII), retained these favourable cell interactive properties, again promoting endothelial cell attachment and proliferation. The thrombogenicity of covalently bound PF8 on PTFE was assessed in both static and dynamic conditions. In static conditions, uncoated PIII treated PTFE was more thrombogenic than untreated PTFE, while PF8 coating reduced thrombogenicity. Under flow, there was no difference in the thrombogenicity of PF8 coated PTFE and untreated PTFE. Immobilised PF8 shows a striking ability to promote attachment and growth of endothelial cells on PTFE, while providing a non-thrombogenic surface. These features make PF8 a promising candidate to improve the biocompatibility of current synthetic vascular grafts. Crown Copyright © 2014. Published by Elsevier B.V. All rights reserved.

  16. 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

  17. Fluoropolymer-coated dacron versus PTFE grafts for femorofemoral crossover bypass: randomised trial

    DEFF Research Database (Denmark)

    Eiberg, JP; Røder, Ole Christian; Stahl-Madsen, M

    2006-01-01

    To investigate whether patency of a thin walled 8 mm fluoropassivated Dacron graft was similar to that of a standard 8mm PTFE graft for femorofemoral crossover bypass surgery.......To investigate whether patency of a thin walled 8 mm fluoropassivated Dacron graft was similar to that of a standard 8mm PTFE graft for femorofemoral crossover bypass surgery....

  18. Preparation of PVDF and PTFE membranes for fuel cell use; Preparacao de membranas de PVDF e PTFE enxertadas e sulfonadas para uso em celula a combustivel

    Energy Technology Data Exchange (ETDEWEB)

    Geraldes, Adriana N.; Zen, Heloisa A.; Ferreira, Henrique P.; Parra, Duclerc F.; Lugao, Ademar B.; Linardi, Marcelo [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)], e-mail: angeral@ipen.br

    2007-07-01

    Grafting of styrene onto polyvinylidenefluoride (PVDF), polytetrafluoroethylene (PTFE) was studied using styrene/toluene solutions. First, PTFE and PVDF films were prepared and the process was conducted by radiation induced graft polymerization of styrene, by a Co{sup 60} source. Films of PTFE and PVDF were immersed in styrene/toluene at 1:1 (v/v) concentration and then submitted to gamma radiation at 20 kGy doses. After irradiation, the samples were evaluated at the period of 21 days at room temperature in order to observe the grafting degree. Chemical changes in the PVDF and PTFE films after styrene grafting were monitored and the results were evaluated by FTIR, DSC, TGA and degree of grafting (DOG). The ion exchange capacity (IEC) after sulfonation of 1, 2 and 24 hours were also determined. (author)

  19. Surface modification and adhesion improvement of PTFE film by ion beam irradiation

    International Nuclear Information System (INIS)

    Lee, S.W.; Hong, J.W.; Wye, M.Y.; Kim, J.H.; Kang, H.J.; Lee, Y.S.

    2004-01-01

    The polytetrafluoroethylene (PTFE) surfaces, modified by 1 kV Ar + or O 2 + ion beam irradiation, was investigated with in-situ X-ray photoelectron spectroscopy (XPS), scanning electron micrographs (SEM), atomic force microscopy (AFM) measurements. The surface of PTFE films modified by Ar + ion irradiation was carbonized and the surface roughness increased with increasing ion doses. The surface of PTFE films modified by both Ar + ion in O 2 atmosphere and O 2 + ion irradiation formed the oxygen function group on PTFE surface, and the surface roughness change was relatively small. The adhesion improvement in Ar + ion irradiated PTFE surface is attributed to mechanical interlocking due to the surface roughness and -CF-radical, but that in Ar + ion irradiation in an O 2 atmosphere was contributed by the C-O complex and -CF-radical with mechanical interlocking. The C-O complex and -CF-radical in O 2 + ion irradiated surface contributed to the adhesion

  20. Fabrication and Characteristics of Al/PTFE Multilayers and Application in Micro-initiator

    Science.gov (United States)

    Zhang, Yuxin; Jiang, Hongchuan; Zhao, Xiaohui; Zhang, Wanli; Li, Yanrong

    2017-12-01

    In this paper, a micro-initiator was designed and fabricated by integrating Al/PTFE multilayers with a Cu film bridge. The regularity layer structure and interface composition of Al/PTFE multilayers was analysed by transmission electron microscope and X-ray photoelectron spectroscopy, respectively. The heat release reaction in Al/PTFE multilayers can be triggered with reaction temperature of 430 °C, and the overall heat of reaction is 3192 J/g. Al/PTFE multilayers with bilayer thickness of 200 nm was alternately deposited on a Cu film bridge to improve the electric explosion performances. Compared to Cu film bridge, the Al/PTFE/Cu integrated film bridge exhibits improved performances with longer explosion duration time, more violent explosion phenomenon and larger quantities of ejected product particles.

  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. 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)

  3. Thermally stimulated current in PTFE and its application in radiation dosimetry

    International Nuclear Information System (INIS)

    Ozdemir, S.

    1985-01-01

    Thermally Stimulated Current (TSC) measurement was made on PTFE (Polytetrafluoro ethylene) in an attempt to develop an integrating radiation dosimeter material and the system. TSC spectra, dose response, energy response, fading and background charge stability characteristics were used as a measure of suitability of various untreated and heat treated PTFE samples for dosimetry applications. For practical TSC dosimetry system, it was discovered that the PTFE samples should be subjected to a specific heat treatment in order to produce samples with better dosimeter characteristics. A treatment at a temperature of 240 C produces a high dose response and low fading characteristics. It was found that the spurious charges due to storage and low sensitivity to irradiation caused the limitation in the measurement of low doses with PTFE samples for personnel protection. However, a TSC Dosimetry system using PTFE is proposed which is suitable for radiation doses in the radiotherapy range from *approx* 50 to *approx* 800 mGy. (author)

  4. Effect of gamma radiation on graphite – PTFE dry lubrication system

    International Nuclear Information System (INIS)

    Singh, Sachin; Tyagi, Mukti; Seshadri, Geetha; Tyagi, Ajay Kumar; Varshney, Lalit

    2017-01-01

    An effect of gamma radiation on lubrication behavior of graphite -PTFE dry lubrication system has been studied using (TR-TW-30L) tribometer with thrust washer attachment in plane contact. Different compositions of graphite and PTFE were prepared and irradiated by gamma rays. Gamma radiation exposure significantly improves the tribological properties indicated by decrease in coefficient of friction and wear properties of graphite -PTFE dry lubrication system. SEM and XRD analysis confirm the physico-chemical modification of graphite-PTFE on gamma radiation exposure leading to a novel dry lubrication system with good slip and anti friction properties. - Highlights: • Novel dry lubrication system of graphite -PTFE using gamma radiation. • Gamma radiation processing. • Reduction in coefficient of friction, frictional torque and wear loss of developed dry lubrication system.

  5. Identification of animal fats via compound specific δ13C values of individual fatty acids: assessments of results for reference fats and lipid extracts of archaeological pottery vessels

    Directory of Open Access Journals (Sweden)

    Richard P. Evershed

    2002-12-01

    Full Text Available The possibility of obtaining molecular information from lipid residues associated with archaeological pottery has dramatically increased the potential for deriving new information on the use of ancient vessels and the commodities processed therein. Motivated by the high proportion of the archaeological potsherds that have been shown to contain animal fats, a new approach invol- ving compound specific stable isotope analysis of remnant fats has been developed to retrieve infor- mation which will allow new insights into animal exploitation, dietary preferences and vessel use amongst prehistoric peoples. The new approach uses the δ13C values of the major saturated fatty acid (C16:0 and C18:0 determined by gas chromatography-combustion-isotope ratio mass spectrometry (GC–C–IRMS to characterise the origins of animal fat recovered from archaeological pottery.

  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. Research vessels

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, P.S.

    The role of the research vessels as a tool for marine research and exploration is very important. Technical requirements of a suitable vessel and the laboratories needed on board are discussed. The history and the research work carried out...

  8. Preparation and Properties of PTFE-PMMA Core-Shell Nanoparticles and Nanocomposites

    Directory of Open Access Journals (Sweden)

    Diego Antonioli

    2012-01-01

    Full Text Available The preparation of polytetrafluoroethylene-poly(methyl methacrylate (PTFE-PMMA core-shell particles was described, featuring controlled size and narrow size distribution over a wide compositional range, through a seeded emulsion polymerization starting from a PTFE seed of 26 nanometers. Over the entire MMA/PTFE range, the particle size increases as the MMA/PTFE ratio increases. A very precise control over the particle size can be exerted by properly adjusting the ratio between the monomer and the PTFE seed. Particles in the 80–240 nm range can be prepared with uniformity indexes suited to build 2D and 3D colloidal crystals. These core-shell particles were employed to prepare nanocomposites with different compositions, through an annealing procedure at a temperature higher than the glass transition temperature of the shell forming polymer. A perfect dispersion of the PTFE particles within the PMMA matrix was obtained and optically transparent nanocomposites were prepared containing a very high PTFE amount.

  9. MgTiO3 filled PTFE composites for microwave substrate applications

    International Nuclear Information System (INIS)

    Yuan, Y.; Zhang, S.R.; Zhou, X.H.; Li, E.Z.

    2013-01-01

    MgTiO 3 filled PTFE composite substrates were fabricated for microwave circuit applications. The filler content in the PTFE matrix was varied from 30 to 70 wt%. Low loss MgTiO 3 ceramic powder was prepared by the solid state ceramic route. The phase formation of MgTiO 3 was studied by powder X-ray diffraction analysis. Morphology of the composites and dispersion of filler in the PTFE matrix was studied using scanning electron microscopy. Microwave dielectric properties of the composites with respect to filler loading were measured by stripline resonator method using Vector Network Analyzer. Different theoretical modeling approaches were used to predict the dielectric constant of PTFE ceramic composites with respect to filler loading. The linear coefficient of thermal expansion of the composites was investigated. Moisture absorption of the composites was found out conforming to IPC-TM-650 2.6.2. - Highlights: • We prepare MT/PTFE composite by cold pressing and hot treating. • Increasing MT will increase ε r , tan δ and moisture absorption. • Increasing MT will decrease thermal expansion coefficient. • MT/PTFE composite has an ε r of 4.3 and a tan δ of 0.00097 at 50 wt% filler loading. • MT/PTFE composite are promising candidates for microwave circuit applications

  10. XPS analysis of the effect of fillers on PTFE transfer film development in sliding contacts

    Science.gov (United States)

    Blanchet, T. A.; Kennedy, F. E.; Jayne, D. T.

    1993-01-01

    The development of transfer films atop steel counterfaces in contact with unfilled and bronze-filled PTFE has been studied using X-ray photoelectron spectroscopy. The sliding apparatus was contained within the vacuum of the analytical system, so the effects of the native oxide, hydrocarbon, and adsorbed gaseous surface layers of the steel upon the PTFE transfer behavior could be studied in situ. For both the filled and the unfilled PTFE, cleaner surfaces promoted greater amounts of transfer. Metal fluorides, which formed at the transfer film/counterface interface, were found solely in cases where the native oxide had been removed to expose the metallic surface prior to sliding. These fluorides also were found at clean metal/PTFE interfaces formed in the absence of frictional contact. A fraction of these fluorides resulted from irradiation damage inherent in XPS analysis. PTFE transfer films were found to build up with repeated sliding passes, by a process in which strands of transfer filled in the remaining counterface area. Under these reported test conditions, the transfer process is not expected to continue atop previously deposited transfer films. The bronze-filled composite generated greater amounts of transfer than the unfilled PTFE. The results are discussed relative to the observed increase in wear resistance imparted to PTFE by a broad range of inorganic fillers.

  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. Pulse electrodeposition of self-lubricating Ni–W/PTFE nanocomposite coatings on mild steel surface

    Energy Technology Data Exchange (ETDEWEB)

    Sangeetha, S. [Advanced Nanocomposite Coatings Laboratory, Department of Industrial Chemistry, Alagappa University, Karaikudi 630 003 (India); Kalaignan, G. Paruthimal, E-mail: pkalaignan@yahoo.com [Advanced Nanocomposite Coatings Laboratory, Department of Industrial Chemistry, Alagappa University, Karaikudi 630 003 (India); Anthuvan, J. Tennis [M. Kumarasamy College of Engineering, Karur, Tamil Nadu (India)

    2015-12-30

    Graphical abstract: - Highlights: • PTFE polymer inclusion on Ni–W alloy matrix was electrodeposited by pulse current method. • Tribological properties and electrochemical characterizations of the nanocomposite coatings were analyzed. • The hydrophobic behaviour of Ni–W/PTFE nanocomposite coating was measured. • Ni–W/PTFE nanocomposite coatings have showed superior tribological properties and corrosion resistance relative to that of the Ni–W alloy matrix. - Abstract: Ni–W/PTFE nanocomposite coatings with various contents of PTFE (polytetafluoroethylene) particles were prepared by pulse current (PC) electrodeposition from the Ni–W plating bath containing self lubricant PTFE particles to be co-deposited. Co-deposited PTFE particulates were uniformly distributed in the Ni–W alloy matrix. The coatings were characterized by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDAX), X-ray Diffractometry (XRD) and Vicker's micro hardness tester. Tafel Polarization and electrochemical Impedance methods were used to evaluate the corrosion resistance behaviour of the nanocomposite coatings in 3.5% NaCl solution. It was found that, the Ni–W/PTFE nanocomposite coating has better corrosion resistance than the Ni–W alloy coating. Surface roughness and friction coefficient of the coated samples were assessed by Mitutoyo Surftest SJ-310 (ISO1997) and Scratch tester TR-101-M4 respectively. The contact angle (CA) of a water droplet on the surface of nanocomposite coating was measured by Optical Contact Goniometry (OCA 35). These results indicated that, the addition of PTFE in the Ni–W alloy matrix has resulted moderate microhardness, smooth surface, less friction coefficient, excellent water repellency and enhanced corrosion resistance of the nanocomposite coatings.

  14. On compression and damage evolution in PTFE and PEEK

    Science.gov (United States)

    Rau, C.; Parry, S.; Garcea, S. C.; Bourne, N. K.; McDonald, S. A.; Eastwood, D. S.; Brown, E. N.; Withers, P. J.

    2017-01-01

    The well-known Taylor cylinder impact test, that follows the impact of a flat-ended cylindrical rod onto a rigid stationary anvil, is conducted over a range of impact speeds for two polymers, PTFE and PEEK. In previous work experiments and a model were developed to capture the deformation behaviour of the rod after impact. A distinctive feature of these works was that a region in which both spatial and temporal variation of both longitudinal and radial deformation showed evidence of changes in phase within the material. This region is X-ray imaged in a range of impacted targets at the I13 Imaging and Coherence beam line at the Diamond synchrotron. Further techniques were fielded to resolve compressed regions within the recovered polymer cylinders that showed a fracture zone in the impact region. This shows the transit of damage from ductile to brittle failure results from previously undetected internal failure.

  15. Radiation-induced crosslinking of short Fiber-filled polytetrafluoroethylene (PTFE)

    International Nuclear Information System (INIS)

    Oshima, Akihiro; Udagawa, Akira; Morita, Yousuke

    1999-02-01

    The radiation-induced crosslinking of PTFE mixed with short fibers as glass or carbon fibers was studied for processing the composite materials. The crosslinking behaviors did not change by mixing of the fiber under the irradiation condition in oxygen-free atmosphere at temperature at temperature of 330degC - 350degC. The effect of reinforcement by the fibers in the fabricated composite materials was supposed to be a morphological change of PTFE because and adhesion between PTFE and the fibers was hardly observed in the composite materials. (author)

  16. 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.

  17. Biodegradation of total petroleum hydrocarbons from acidic sludge produced by re-refinery industries of waste oil using in-vessel composting.

    Science.gov (United States)

    Asgari, Alireza; Nabizadeh, Ramin; Mahvi, Amir Hossein; Nasseri, Simin; Dehghani, Mohammad Hadi; Nazmara, Shahrokh; Yaghmaeian, Kamyar

    2017-01-01

    In Iran, re-refinery industry has been developed many years ago based on the acid-clay treatment. Acidic sludge with high concentration of total petroleum hydrocarbon (TPH) is the final products of some facilities. In this study removal of TPH by aerated in-vessel composting was investigated. In order to microorganisms seeding and nutrient providing, urban immature compost was added as an amendment to acidic sludge. The ratios of acidic sludge (AS) to compost were, 1:0 (as control), 1:5, 1:8, 1:10, 1:15, 1:20, 1:30, 1:40, 1:50, 1:75 and 1:100 (as dry basis) at a C: N: P ratio of 100:5:1 and 45-65% moisture content for 70 days. The removal efficiency in all reactors was more than 48%. The highest and lowest TPH removal was observed in 1:5 (71.56%) and 1:100 (48.53%) mixing ratios, respectively. The results of the control reactors showed that biological treatment was the main mechanism for TPH removal. Experimental data was fitted second order kinetic model ( R 2  > 0.8006). Degradation of TPH in 1:5 mixing ratio (k 2  = 0.0038 gmg -1 d -1 ; half-life = 3.08d) was nearly three times faster than 1:100 mixing ratio (k 2  = 0.0238; half-life = 8.96d). The results of the control reactors showed that biological treatment was the main mechanism for TPH removal. The results of this study revealed in-vessel composting with immature urban compost as the amendment maybe recommended as an effective method for TPH remediation.

  18. Non-Cyanide Electrodeposited Ag–PTFE Composite Coating Using Direct or Pulsed Current Deposition

    Directory of Open Access Journals (Sweden)

    Raymond Sieh

    2016-07-01

    Full Text Available The effects of FC-4 cationic surfactant on electrodeposited Ag–PTFE composite coating using direct or pulsed currents were studied using scanning electron microscope (SEM, energy dispersive X-ray (EDS, optical microscope, and a linear tribometer. FC-4:PTFE in various ratios were added to a non-cyanide succinimide silver complex bath. Direct or pulsed current method was used at a constant current density to enable comparison between both methods. A high incorporation rate of PTFE was successfully achieved, with pulsed current being highly useful in increasing the amount of PTFE in the composite coating. The study of coating wear under sliding showed that a large majority of the electrodeposited coatings still managed to adhere to the substrate, even after 10 wear cycles of sliding tests. Performance improvements were achieved on all the samples with a coefficient of friction (CoF between 0.06 and 0.12.

  19. In vitro microbiologic evaluation of PTFE and cotton as spacer materials.

    Science.gov (United States)

    Paranjpe, Avina; Jain, Sumita; Alibhai, Karim J; Wadhwani, Chandur P; Darveau, Richard P; Johnson, James D

    2012-09-01

    To microbiologically evaluate the efficacy of cotton and polytetrafluoroethylene (PTFE) tape used as spacer materials. Twenty-six extracted human molars were restored using either cotton or PTFE tape as spacers under a standardized provisional restorative material (Cavit). The teeth were incubated for 7 days in a culture of Streptococcus gordonii or in liquid media alone. The spacers were removed and tested for bacterial contamination. The access cavities were also evaluated for bacterial contamination. Nine of 10 teeth with cotton spacers and one of 10 teeth with PTFE spacers were positive for S gordonii growth. The nine teeth in the cotton group also showed contamination of the access cavities. Even under optimal conditions, cotton spacers may cause leakage into the access cavities. Cotton fibers may serve as a route for bacterial contamination of the access cavities and root canal space. In contrast, PTFE tape did not provide an avenue for bacterial contamination.

  20. The production and characterization of Ptfe bonded Nd-Fe-B magnets

    International Nuclear Information System (INIS)

    Mokal, B.; Williams, A.J.; Hay, J.N.; Harris, I.R.

    1996-01-01

    A study of the processing and characteristics of PTFE bonded Nd Fe B magnets has been carried out. PTFE was used because of its low coefficient of friction, thus enabling its flow between the particles of Nd Fe B powder. PTFE also increases the resistance to corrosion of the magnet. In these investigations, the production of bonded magnets by cold compaction and by hot processing (HP) of MQ powders using PTFE as the binder was investigated . Magnetic, microstructural, and mechanical properties were investigated and are presented together with a correlation with the different processing techniques used. The corrosion behaviour of the hot pressed magnets was also investigated. These studies could lead to the development of simpler and more effective processing routes for the production of bonded magnets. (author)

  1. Preparation of Pt-PTFE hydrophobic catalyst for hydrogen-water isotope exchange

    International Nuclear Information System (INIS)

    Li Junhua; Kang Yi; Han Yande; Ruan Hao; Dou Qincheng; Hu Shilin

    2001-01-01

    The hydrophobic catalyst used in the hydrogen-water isotope exchange is prepared with Pt as the active metal, PTFE as the hydrophobic material, active carbon or silicon dioxide as the support. The isotope catalytic exchange reaction between hydrogen and water is carried out in the trickle bed and the effects of different carriers, mass fraction of Pt and PTFE on the catalytic activity are discussed. The experimental results show that the activity of Pt-C-PTFE hydrophobic catalyst with the ratio between PTFE and Pt-C from 1 to 2 is higher than other kinds of catalysts and the overall volume transfer coefficient is increased with the increasing of the hydrogen flow rate and reaction temperature

  2. Highly oriented poly(di-n-alkylsilylene) films on oriented PTFE substrates

    NARCIS (Netherlands)

    Frey, H.H.; Frey, Holger; Sheiko, Sergej; Sheiko, S.; Moller, M.; Möller, Martin; Wittmann, Jean-Claude; Lot, Bernard

    1993-01-01

    Highly oriented polysilylene layers have potential applications in electrophotography, nonlinear optics, display fabrication, and microlithography. The preparation of such layers by crystallization on a highly oriented PTFE substrate is reported, and their assessment by optical birefringence,

  3. Synthesis and characterization of c-PTFE-g-styrene copolymer by preirradiation method

    International Nuclear Information System (INIS)

    Oktaviani; Ambyah Suliwarno; Tita Puspitasari

    2011-01-01

    Crosslinked-poly(tetrafluoroethylene)-graf-styrene (c-PTFE-g-styrene) copolymer has been synthesized by copolymerization preirradiation method. Irradiation onto c-PTFE films was carried out by γ-ray with irradiation doses of 15, 30, and 45 kGy at room temperature. Styrene was grafted into irradiated c-PTFE films in the temperature range of between 600-90°C. Parameter observed in the grafting process was degree of grafting. The results showed that the degree of grafting increased with increasing of irradiation doses. The highest degree of grafting was 25,44 % obtained at temperature of 70°C and still increased up to 25,73% with increasing of the grafting time. The optimum grafting time was 2 hours. Chemical and physical properties of c-PTFE-g-styrene film were analyzed by IR spectrophotometer and Scanning Electron Microscopy (SEM). (author)

  4. The Mechanical and Reaction Behavior of PTFE/Al/Fe2O3 under Impact and Quasi-Static Compression

    Directory of Open Access Journals (Sweden)

    Jun-yi Huang

    2017-01-01

    Full Text Available Quasi-static compression and drop-weight test were used to characterize the mechanical and reaction behavior of PTFE/Al/Fe2O3 composites. Two kinds of PTFE/Al/Fe2O3 composites were prepared with different mass of PTFE, and the reaction phenomenon and stress-strain curves were recorded; the residuals after reaction were analyzed by X-ray diffraction (XRD. The results showed that, under quasi-static compression condition, the strength of the materials is increased (from 37.1 Mpa to 77.2 Mpa with the increase of PTFE, and the reaction phenomenon occurred only in materials with high PTFE content. XRD analysis showed that the reaction between Al and Fe2O3 was not triggered with identical experimental conditions. In drop-weight tests, PTFE/Al/Fe2O3 specimens with low PTFE content were found to be more insensitive by high-speed photography, and a High Temperature Metal Slag Spray (HTMSS phenomenon was observed in both kinds of PTFE/Al/Fe2O3 composites, indicating the existence of thermite reaction, which was confirmed by XRD. In PTFE/Al/Fe2O3 system, the reaction between PTFE and Al precedes the reaction between Al and Fe2O3.

  5. Study on the performance of MoS2 modified PTFE composites by molding process

    Science.gov (United States)

    Ma, Weiqiang; Hou, Genliang; Bi, Song; Li, Ping; Li, Penghui

    2017-10-01

    MoS2 filled PTFE composites were prepared by cold pressing and sintering molding. The compressive and creep properties of composite materials were analyzed by controlling the size of molded composites during molding. The results show that the composites have the best compressive and creep resistance when the molding pressure is 55 MPa in the MoS2 composites with 15% mass fraction, which is a practical reference for the preparation of MoS2-modified PTFE composites.

  6. Thermoluminescence sensitivity variations in LiF PTFE dosemeters incurred by improper handling procedures

    CERN Document Server

    Mason, E W; MacKinlay, Alistair F; Saunders, D

    1975-01-01

    A systematic study of some anomalous darkening effects and thermoluminescence sensitivity variations observed in LiF:PTFE thermoluminescent dosemeters is described. Various likely causes of such effects have been investigated. The manufacturer's recommended cleaning procedures have been found to be inadequate and, in some cases, have been found to actually promote discolouration of the dosemeters. Recommendations are given for the successful use of LiF:PTFE thermoluminescent dosemeters in personal dosimetry.

  7. Preparation, Properties, and Self-Assembly Behavior of PTFE-Based Core-Shell Nanospheres

    International Nuclear Information System (INIS)

    Sparnacci, K.; Antonioli, D.; Deregibus, S.; Laus, M.; Zuccheri, G.; Boarino, L.; De Leo, N.; Comoretto, D.

    2012-01-01

    Nano sized PTFE-based core-shell particles can be prepared by emulsifier-free seed emulsion polymerization technique starting from spherical or rod-like PTFE seeds of different size. The shell can be constituted by the relatively high Tg polystyrene and polymethylmethacrylate as well as by low Tg polyacrylic copolymers. Peculiar thermal behavior of the PTFE component is observed due to the high degree of PTFE compartmentalization. A very precise control over the particle size can be exerted by properly adjusting the ratio between the monomers and the PTFE seed. In addition, the particle size distribution self-sharpens as the ratio monomer/PTFE increases. Samples with uniformity ratios suited to build 2D and 3D colloidal crystals are easily prepared. In particular, 2D colloidal crystal of spheres leads to very small 2D nanostructuration, useful for the preparation of masks with a combination of nanosphere lithography and reactive ion etching. 3D colloidal crystals were also obtained featuring excellent opal quality, which is a direct consequence of the monodispersity of colloids used for their growth.

  8. Synchrotron radiation induced direct photo-etching and surface modification of PTFE

    International Nuclear Information System (INIS)

    Oshima, Akihiro; Washio, Masakazu

    2003-01-01

    In the first part of this article, we have described and discussed the measurement results of etching rates by direct photo-etching using Synchrotron Radiation (SR) for various kind of crosslinked PTFEs, which were prepared by different crosslinking doses, comparing with the non-crosslinked PTFE. It has been found that the etching rates obtained for crosslinked PTFE were much larger than that of non-crosslinked one. These results are not described by simple consideration such as the G values of main chain scission. We propose that the etching rates should be discussed by the complex mechanism through at least two different steps such as polymer decomposition and fragment desorption. In the second part of the article, we have described and discussed the abnormal reaction induced at the surface region after the SR etching for non-crosslinked PTFE. Through the measurements using DSC and solid state 19 F-NMR, we have confirmed the crosslinking reaction of PTFE even in solid state PTFE. This should be induced by the very high density radical formation in very thin area of PTFE films by SR radiation. (author)

  9. Preparation, Properties, and Self-Assembly Behavior of PTFE-Based Core-Shell Nanospheres

    Directory of Open Access Journals (Sweden)

    Katia Sparnacci

    2012-01-01

    Full Text Available Nanosized PTFE-based core-shell particles can be prepared by emulsifier-free seed emulsion polymerization technique starting from spherical or rod-like PTFE seeds of different size. The shell can be constituted by the relatively high Tg polystyrene and polymethylmethacrylate as well as by low Tg polyacrylic copolymers. Peculiar thermal behavior of the PTFE component is observed due to the high degree of PTFE compartmentalization. A very precise control over the particle size can be exerted by properly adjusting the ratio between the monomers and the PTFE seed. In addition, the particle size distribution self-sharpens as the ratio monomer/PTFE increases. Samples with uniformity ratios suited to build 2D and 3D colloidal crystals are easily prepared. In particular, 2D colloidal crystal of spheres leads to very small 2D nanostructuration, useful for the preparation of masks with a combination of nanosphere lithography and reactive ion etching. 3D colloidal crystals were also obtained featuring excellent opal quality, which is a direct consequence of the monodispersity of colloids used for their growth.

  10. Ion beam deposition of DLC and nitrogen doped DLC thin films for enhanced haemocompatibility on PTFE

    International Nuclear Information System (INIS)

    Srinivasan, S.; Tang, Y.; Li, Y.S.; Yang, Q.; Hirose, A.

    2012-01-01

    Diamond-like carbon (DLC) and N-doped DLC (DLC:N) thin films have been synthesized on polytetrafluroethylene (PTFE) and silicon wafers using ion beam deposition. Raman spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy and scanning electron microscopy were used to study the structural and morphological properties of the coated surface. The results show that the ion beam deposited DLC thin films exhibit high hardness and Young's modulus, low coefficient of friction and high adhesion to the substrate. Low concentration of nitrogen doping in DLC improves the mechanical properties and reduces the surface roughness. DLC coating decreases the surface energy and improves the wettability of PTFE. The platelet adhesion results show that the haemocompatibility of DLC coated PTFE, especially DLC:N coated PTFE, has been significantly enhanced as compared with uncoated PTFE. SEM observations show that the platelet reaction on the DLC and DLC:N coated PTFE was minimized as the platelets were much less aggregated and activated.

  11. Grafting of Styrene onto Commercial Polytetrafluorethylene (PTFE) Membrane and Sulfonation for Possible use in Fuel Cell

    International Nuclear Information System (INIS)

    Abdel-Hady, E.E.; Abdel-Hamed, M.O.; Hammam, A.M.; El-toony, M.M.

    2010-01-01

    The purpose of this work is to initiate the fundamental research necessary for the development of a novel proton-exchange membranes (PEM) to overcome the material and performance limitations of the s tate of the art N afion that is used in both hydrogen and methanol fuel cells. Silica was inserted in commercial PTFE membrane in ratio 8%. Gamma irradiation was used for grafting of different ratios of styrene onto the membrane in one and two steps. Methacrylic acid and styrene were used as binary monomers for grafting of such membranes to raise the grafting percentage. Thermal characterization of the grafted membrane was discussed using thermal gravimetric analysis (TGA). The mechanical properties were tested by measuring ultimate tensile value, and Young modulus. The positron annihilation lifetime spectroscopy has been used to investigate the free volume hole size, while the surface morphology of the membrane was studied by scanning electron microscope (SEM). It was found that the maximum water uptake of the sulfonated membrane reached 20% by weight. The proton conductivity of the prepared polymer electrolyte was measured by ac impedance spectroscopic analysis. And it was found to be 0.9 x 10 -4 ohm -1 cm -1 .

  12. The Scandinavian Propaten(®) trial - 1-year patency of PTFE vascular prostheses with heparin-bonded luminal surfaces compared to ordinary pure PTFE vascular prostheses - a randomised clinical controlled multi-centre trial.

    Science.gov (United States)

    Lindholt, J S; Gottschalksen, B; Johannesen, N; Dueholm, D; Ravn, H; Christensen, E D; Viddal, B; Flørenes, T; Pedersen, G; Rasmussen, M; Carstensen, M; Grøndal, N; Fasting, H

    2011-05-01

    To compare 1-year potencies' of heparin-bonded PTFE [(Hb-PTFE) (Propaten(®))] grafts with those of ordinary polytetraflouroethylene (PTFE) grafts in a blinded, randomised, clinically controlled, multi-centre study. Eleven Scandinavian centres enrolled 569 patients with chronic functional or critical lower limb ischaemia who were scheduled to undergo femoro-femoral bypass or femoro-poplitaeal bypass. The patients were randomised 1:1 stratified by centre. Patency was assessed by duplex ultrasound scanning. A total of 546 patients (96%) completed the study with adequate follow-up. Perioperative bleeding was, on average, 370 ml with PTFE grafts and 399 ml with Heparin-bonded PTFE grafts (p = 0.32). Overall, primary patency after 1 year was 86.4% for Hb-PTFE grafts and 79.9% for PTFE grafts (OR = 0.627, 95% CI: 0.398; 0.989, p = 0.043). Secondary patency was 88% in Hb-PTFE grafts and 81% in PTFE grafts (OR = 0.569 (0.353; 0.917, p = 0.020)). Subgroup analyses revealed that significant reduction in risk (50%) was observed when Hb-PTFE was used for femoro-poplitaeal bypass (OR = 0.515 (0.281; 0.944, p = 0.030)), and a significant reduction in risk (50%) was observed with Hb-PTFE in cases with critical ischaemia (OR = 0.490 (0.249; 0.962, p = 0.036)). The Hb-PTFE graft significantly reduced the overall risk of primary graft failure by 37%. Risk reduction was 50% in femoro-poplitaeal bypass cases and in cases with critical ischaemia. Copyright © 2011. Published by Elsevier Ltd.

  13. Acid dip for dosemeter

    International Nuclear Information System (INIS)

    Stewart, J.C.; McWhan, A.F.

    1982-01-01

    Background signal in a PTFE based dosemeter caused by impurities in the PTFE and in the active component such as lithium fluoride is substantially reduced by treating the dosemeter with acid. The optimum treatment involves use of hydrofluoric acid at room temperature for approximately one minute, followed by thorough washing with methanol, and finally drying. This treatment is best applied after the original manufacture of the dosemeters. It may also be applied to existing dosemeters after they have been in use for some time. The treatment produces a permanent effect in reducing both the light induced signal and the non-light induced signal. The process may be applied to all types of dosemeter manufactured from PTFE or other plastics or resins which are able to resist brief exposure to acid. The treatment works particularly well with dosemeters based on PTFE and lithium fluoride. It is also applicable to dosemeters based on calcium sulphate, lithium borate and magnesium borate. Acids which may be used include hydrofluoric, hydrochloric, nitric, phosphoric and sulphuric. (author)

  14. Dextran grafting on PTFE surface for cardiovascular applications

    Science.gov (United States)

    Michel, Eléonore C; Montaño-Machado, Vanessa; Chevallier, Pascale; Labbé-Barrère, Amélie; Letourneur, Didier; Mantovani, Diego

    2014-01-01

    The modification of biomaterial surfaces with biomolecules influences the biological response. In this work, caboxymethyldextrans (CMD) with different degrees of substitution have been grafted to surfaces by introduction of amino moieties directly onto the substrate surface. Polytetrafluoroethylene was selected as a model substrate for biomaterial as it is already largely used for cardiovascular clinical applications. Firstly, CMD polymers were characterized by FTIR, 1H-NMR, and conductimetric titration. Then, the coatings have been analyzed by XPS to confirm the grafting and determine the composition. Once characterized, biological performances of CMD coatings were investigated. The hemocompatibility was ascertained using the free hemoglobin method. The effects on endothelial and smooth muscle cell adhesion were also studied. Results indicated that CMD at a 0.2 substitution degree, significantly influenced the biological property of PTFE by exhibiting non-thrombogenic properties as well as enhancing endothelial cell adhesion along with limiting smooth muscle cell adhesion. This work suggested the creation of versatile pro-active biomaterials suitable for different biomedical applications. PMID:25482414

  15. BRDF Calibration of Sintered PTFE in the SWIR

    Science.gov (United States)

    Georgiev, Georgi T.; Butler, James J.

    2009-01-01

    Satellite instruments operating in the reflective solar wavelength region often require accurate and precise determination of the Bidirectional Reflectance Distribution Function (BRDF) of laboratory-based diffusers used in their pre-flight calibrations and ground-based support of on-orbit remote sensing instruments. The Diffuser Calibration Facility at NASA's Goddard Space Flight Center is a secondary diffuser calibration standard after NEST for over two decades, providing numerous NASA projects with BRDF data in the UV, Visible and the NIR spectral regions. Currently the Diffuser Calibration Facility extended the covered spectral range from 900 nm up to 1.7 microns. The measurements were made using the existing scatterometer by replacing the Si photodiode based receiver with an InGaAs-based one. The BRDF data was recorded at normal incidence and scatter zenith angles from 10 to 60 deg. Tunable coherent light source was setup. Broadband light source application is under development. Gray-scale sintered PTFE samples were used at these first trials, illuminated with P and S polarized incident light. The results are discussed and compared to empirically generated BRDF data from simple model based on 8 deg directional/hemispherical measurements.

  16. 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

  17. Electrophoretic deposition (EPD) of hydrous ruthenium oxides with PTFE and their supercapacitor performances

    International Nuclear Information System (INIS)

    Jang, Jong H.; Machida, Kenji; Kim, Yuri; Naoi, Katsuhiko

    2006-01-01

    The effect of PTFE addition was investigated for the electrophoretic deposition (EPD) of hydrous ruthenium oxide electrodes. Mechanical stability of electrode layers, together with deposition yield, was enhanced by using hydrous ruthenium oxide/PTFE dispersions. High supercapacitor performance was obtained for the electrodes prepared with 2% PTFE and 10% water. When PTFE content was higher, the rate capability became poor with low electronic conductivity; higher water content than 10% resulted in non-uniform depositions with poor cycleability and power capability. When electrodes were heat treated at 200 deg. C for 10 h, the specific energy was as high as 17.6 Wh/kg based on single electrode (at 200 W/kg); while utilizable energy was lower with heat treatment time of 1 and 50 h, due to the high resistance and gradual crystallization, respectively. With PTFE addition and heat treatment at 200 deg. C for 10 h, the specific capacitance was increased by 31% (460 → 599 F/g at ca. 0.6 mg/cm 2 ) at 10 mV/s, and the deposition weight was increased up to 1.7 mg/cm 2 with initial capacitance of 350 F/g

  18. Thermal and radiation process for nano-/micro-fabrication of crosslinked PTFE

    International Nuclear Information System (INIS)

    Kobayashi, Akinobu; Oshima, Akihiro; Okubo, Satoshi; Tsubokura, Hidehiro; Takahashi, Tomohiro; Oyama, Tomoko Gowa; Tagawa, Seiichi; Washio, Masakazu

    2013-01-01

    Nano-/micro-fabrication process of crosslinked poly(tetrafluoroethylene) (RX-PTFE) is proposed as a novel method using combined process which is thermal and radiation process for fabrication of RX-PTFE (TRaf process). Nano- and micro-scale patterns of silicon wafers fabricated by EB lithography were used as the molds for TRaf process. Poly(tetrafluoroethylene) (PTFE) dispersion was dropped on the fabricated molds, and then PTFE was crosslinked with doses from 105 kGy to 1500 kGy in its molten state at 340 °C in nitrogen atmosphere. The obtained nano- and micro-structures by TRaf process were compared with those by the conventional thermal fabrication process. Average surface roughness (R a ) of obtained structures was evaluated with atomic force microscope (AFM) and scanning electron microscope (SEM). R a of obtained structures with the crosslinking dose of 600 kGy showed less than 1.2 nm. The fine nano-/micro-structures of crosslinked PTFE were successfully obtained by TRaf process

  19. Comparison of FLIXENE™ and standard PTFE arteriovenous graft for early haemodialysis.

    Science.gov (United States)

    Chiang, Nathaniel; Hulme, Katherine Ria; Haggart, Paul Charles; Vasudevan, Thodur

    2014-01-01

    The purpose is to compare the outcomes of FLIXENE™ arteriovenous graft (AVG) to standard polytetrafluoroethylene (PTFE) AVG for early haemodialysis. This is a prospective observational study of all AVGs placed over a 40-month period between 2008 and 2011 at our vascular unit. Primary outcome was to examine early cannulation rates for FLIXENE™. Secondary outcomes included patency rates, usability of grafts, complications in particular infections, interventions and death in comparison to standard PTFE grafts. Forty-five FLIXENE™ and 19 standard PTFE AVGs were placed in the study period; 89% of FLIXENE™ grafts were used for dialysis, with 78% cannulated within 3 days. At 18 months, primary patency (FLIXENE™ 34% vs standard PTFE 24%), primary assisted patency (35% vs 36%) and secondary patency rate (51% vs 48%) were not statistically different; 20.2% of FLIXENE™ grafts were infected at 18 months requiring explantation compared with 40.3% of standard PTFE grafts (p=0.14). FLIXENE™ can be cannulated for dialysis within 3 days. It has similar patency and complication rates as other prosthetic grafts in the market. In patients who have no access and require urgent dialysis, FLIXENE™ is a viable option.

  20. Control of cell behavior on PTFE surface using ion beam irradiation

    International Nuclear Information System (INIS)

    Kitamura, Akane; Kobayashi, Tomohiro; Meguro, Takashi; Suzuki, Akihiro; Terai, Takayuki

    2009-01-01

    A polytetrafluoroethylene (PTFE) surface is smooth and biologically inert, so that cells cannot attach to it. Ion beam irradiation of the PTFE surface forms micropores and a melted layer, and the surface is finally covered with a large number of small protrusions. Recently, we found that cells could adhere to this irradiated PTFE surface and spread over the surface. Because of their peculiar attachment behavior, these surfaces can be used as biological tools. However, the factors regulating cell adhesion are still unclear, although some new functional groups formed by irradiation seem to contribute to this adhesion. To control cell behavior on PTFE surfaces, we must determine the effects of the outermost irradiated surface on cell adhesion. In this study, we removed the thin melted surface layer by postirradiation annealing and investigated cell behavior on the surface. On the surface irradiated with 3 x 10 16 ions/cm 2 , cells spread only on the remaining parts of the melted layer. From these results, it is clear that the melted layer had a capacity for cell attachment. When the surface covered with protrusions was irradiated with a fluence of 1 x 10 17 ions/cm 2 , the distribution of cells changed after the annealing process from 'sheet shaped' into multicellular aggregates with diameters of around 50 μm. These results indicate that we can control cell behavior on PTFE surfaces covered with protrusions using irradiation and subsequent annealing. Multicellular spheroids can be fabricated for tissue engineering using this surface.

  1. Biocompatibility assessment of porous chitosan-Nafion and chitosan-PTFE composites in vivo.

    Science.gov (United States)

    Liu, Bo-Ji; Ma, Li-Nan; Su, Juan; Jing, Wei-Wei; Wei, Min-Jie; Sha, Xian-Zheng

    2014-06-01

    Chitosan (CS) is widely used as a scaffold material in tissue engineering. The objective of this study was to test whether porous chitosan membrane (PCSM) coating for Nafion used in implantable sensor reduced fibrous capsule (FC) density and promoted superior vascularization compared with PCSM coating for polytetrafluoroethylene (PTFE). PCSM was fabricated with solvent casting/particulate leaching method using silica gel as porogen and characterized in vitro. Then, PCSM-Nafion and PCSM-PTFE composites were assembled with hydrated PCSM and implanted subcutaneously in rats. The histological analysis was performed in comparison with Nafion and PTFE. Implants were explanted 35, 65, and 100 days after the implantation. Histological assessments indicated that both composites achieved presumed effects of porous coatings on decreasing collagen deposition and promoting angiogenesis. PCSM-PTFE exerted higher collagen deposition by area ratio, both within and outside, compared with that of PCSM-Nafion. Angiogenesis within and outside the PCSM-Nafion both increased over time, but that of the PCSM-PTFE within decreased. Copyright © 2013 Wiley Periodicals, Inc.

  2. Production of porous PTFE-Ag composite thin films by pulsed laser deposition

    International Nuclear Information System (INIS)

    Kecskeméti, Gabriella; Hopp, Béla; Smausz, Tomi; Tóth, Zsolt; Szabó, Gábor

    2012-01-01

    The suitability of pulsed laser deposition technique for preparation of polytetrafluoroethylene (PTFE) and silver (Ag) composite thin films was demonstrated. Disk-shaped targets combined from silver and Teflon with various percentages were ablated with pulses of an ArF excimer laser. The chemical composition of the deposited layers was estimated based on deposition rates determined for the pure PTFE and Ag films. EDX and SEM analyses using secondary electron and backscattered electron images proved that the morphology of the layers is determined by the PTFE which is the main constituent and it is transferred mostly in form of grains and clusters forming a sponge-like structure with high specific surface. The Ag content is distributed over the surface of the PTFE structure. Contact angle measurements showed that with increasing the amount of Ag in the deposited layers the surface significantly enhanced the wetting properties. Conductivity experiments demonstrated that when the average silver content of the layers was increased from 0.16 to 3.28 wt% the resistance of our PTFE-Ag composite films decreased with about three orders of magnitudes (from ∼10 MΩ to ∼10 kΩ). The properties of these films suggest as being a good candidate for future electrochemical sensor applications.

  3. Adhesion and removal kinetics of Bacillus cereus biofilms on Ni-PTFE modified stainless steel.

    Science.gov (United States)

    Huang, Kang; McLandsborough, Lynne A; Goddard, Julie M

    2016-01-01

    Biofilm control remains a challenge to food safety. A well-studied non-fouling coating involves codeposition of polytetrafluoroethylene (PTFE) during electroless plating. This coating has been reported to reduce foulant build-up during pasteurization, but opportunities remain in demonstrating its efficacy in inhibiting biofilm formation. Herein, the initial adhesion, biofilm formation, and removal kinetics of Bacillus cereus on Ni-PTFE-modified stainless steel (SS) are characterized. Coatings lowered the surface energy of SS and reduced biofilm formation by > 2 log CFU cm(-2). Characterization of the kinetics of biofilm removal during cleaning demonstrated improved cleanability on the Ni-PTFE coated steel. There was no evidence of biofilm after cleaning by either solution on the Ni-PTFE coated steel, whereas more than 3 log and 1 log CFU cm(-2) of bacteria remained on the native steel after cleaning with water and an alkaline cleaner, respectively. This work demonstrates the potential application of Ni-PTFE non-fouling coatings on SS to improve food safety by reducing biofilm formation and improving the cleaning efficiency of food processing equipment.

  4. Microwave plasma initiated graft copolymerization modification of monomers onto PTFE surface

    International Nuclear Information System (INIS)

    Guan Weishu; Wen Yunjian; Fang Yan; Yin Yongxiang

    1996-02-01

    A graft copolymerization modification technique of monomers onto polytetrafluoroethylene (PTFE) surface initiated by a 2.45 GHz non-equilibrium microwave plasma has been investigated. Standard X-Ray Photoelectron Spectroscopy (XPS), Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), Scanning Electron Microscopy (sEM) and wetting techniques were used for examination and analysis of samples. Considerable changes in chemical structure, composition and in morphology of grafted surface of PTFE were found. Results showed the occurrence of noticeable defluorination and cross-linked structure on grafted surface, and indicated that different kinds and contents of oxygen-containing functional groups were introduced into the surface of PTFE. Wetting and adhesion experiment of the sample proved that significant improvements in hydrophilicity and adhesion of surface were exhibited. These results confirmed the success of grafting. (8 refs., 7 figs., 1 tab.)

  5. Carbon protrusions on PTFE surface prepared by ion irradiation and chemical defluorination

    Science.gov (United States)

    Kobayashi, T.; Iwaki, M.

    2006-01-01

    A surface of PTFE was covered with small protrusions by ion-beam irradiation. In this study, we converted PTFE protrusions into carbon protrusions by a defluorination (carbonization) process using sodium vapor. The morphology, composition and structure were analyzed by SEM-EDX, Raman spectroscopy and TEM. The irradiated PTFE sheets were packed in evacuated glass tubes with a sodium block and kept at 473 K for 2-48 h. The samples were then rinsed in HCl and distilled water to remove NaF precipitates. The EDX measurement showed that the NaF precipitates were completely removed by washing, and the percentage of carbon atoms was controlled from 60% to 99% by the treatment. Raman spectra showed that graphite structures grow during the defluorination process. TEM micrographs showed that the protrusions have a bubble structure and are covered with a thin wall. The carbonized protrusions were conductive and grew perpendicular to the substrate.

  6. Influence of porous PTFE/LDPE/PP composite electret in skin ultrastructure

    International Nuclear Information System (INIS)

    Jiang, J; Liang, Y Y; Tang, Y; Ye, X T; Yang, Y J; Song, M H; Cui, L L; Hou, X M

    2008-01-01

    Corona charging and heat melting method were used to prepare porous PTFE electret and porous PTFE/LDPE/PP composite electret, respectively. After 0.5, 1, 1.5, 3 and 4 hour's action of fluorescein sodium (FINa) and -300V porous PTFE/LDPE/PP composite electret on the excised abdominal skin of rat, the skin structure was studied by means of scanning electron microscopy, transmission electron microscopy and confocal laser scanning microscopy, respectively, to probe the mechanism of electret on transdermal drug delivery. The results indicated that negative electret could increase the transdermal delivery of FINa due to its effect on changing the organized structure of stratum corneum, enlarging the hair follicles, which may be the mechanism of electret in enhancing transdermal drug delivery.

  7. Characterization of structural modifications induced by x radiation on poly-tetra-fluoroethylene (PTFE)

    International Nuclear Information System (INIS)

    Takata, Neide H.

    1995-01-01

    This work deal mainly with the effect induced by X-ray radiation in PTFE as sheet and powder, and the characterization of unirradiated and irradiated samples. Several techniques such as X-ray diffraction (XRD), differential scanning calorimetry (DSC), Raman scattering, infrared photoacoustic spectroscopy (PAS) and electronic absorption spectroscopy were used to characterize the PTFE samples. The irradiation dose up to 640 kGy promoted a slight increase in the crystallinity degree of PTFE, which has been observed by X-ray diffraction, in DSC curves and in the PA spectra. For more than 640 kGy doses, the crystallinity degree remains constant. The increase in crystallinity can be attributed to the scissions of the chain in the amorphous region. (author). 87 refs., 18 figs., 3 tabs

  8. Annealing induced morphological modifications in PTFE films deposited by magnetron sputtering

    Science.gov (United States)

    Tripathi, S.; De, Rajnarayan; Rao, K. Divakar; Haque, S. Maidul; Misal, J. S.; Prathap, C.; Das, S. C.; Ganesan, V.; Sahoo, N. K.

    2017-05-01

    As grown RF magnetron sputtered polytetrafluoroethylene (PTFE) thin films were subjected to vacuum annealing at optimized elevated temperature of 200° C for varying time duration and corresponding surface morphological changes were recorded. The columnar structures appearing after an annealing duration of 2 hours are interesting for fabrication of rough PTFE surfaces towards possible applications in hydrophobicity along with high transmission. Supported by transmission data, the AFM images show a transformation of smooth PTFE surface with less than 2 nm rms roughness to a very rough surface. The results are interpreted in terms of thermal energy induced modifications only at the surface without any change in the original bonding structure on the surface and inside the sample. Preliminary studies indicate that the optimization of roughness and transmission together on such surfaces may lead to high water contact angles.

  9. Effect of gamma and neutron irradiation on the mechanical properties of Spectralon™ porous PTFE

    Energy Technology Data Exchange (ETDEWEB)

    Gourdin, William H., E-mail: gourdin1@llnl.gov [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA USA (United States); Datte, Philip; Jensen, Wayne; Khater, Hesham; Pearson, Mark [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA USA (United States); Girard, Sylvain [Laboratoire Hubert Curien − UMR CNRS 5516, 18 rue du Pr. Benoît Lauras, F-42000 Saint Etienne (France); Paillet, Philippe; Alozy, Eric [CEA, DAM, DIF, F-91297 Arpajon (France)

    2016-11-15

    Highlights: • The effects of neutrons and gammas on PTFE are equivalent for a given absorbed dose. • A neutron fluence of 10{sup 13} n/cm{sup 2} corresponds to a gamma dose of 200 Gy. • The dose-to-fluence conversion factor is approximately 5 × 10{sup 10} n/(cm{sup 2}-Gy). • Irradiation in a low-oxygen environment enhances loads and elongations. • Mechanical properties of PTFE will deteriorate at a neutron fluence of 10{sup 13} n/cm{sup 2}. - Abstract: We establish a correspondence between the mechanical properties (maximum load and failure elongation) of Spectralon™ porous PTFE irradiated with 14 MeV neutrons and 1.17 and 1.33 MeV gammas from a cobalt-60 source. From this correspondence we infer that the effects of neutrons and gammas on this material are approximately equivalent for a given absorbed dose.

  10. Fabrication of micro-prominences on PTFE surface using proton beam writing

    Energy Technology Data Exchange (ETDEWEB)

    Kitamura, Akane, E-mail: ogawa.akane@jaea.go.jp [Department of Advanced Radiation Technology, Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki-Machi, Takasaki, Gunma 370-1292 (Japan); Satoh, Takahiro; Koka, Masashi [Department of Advanced Radiation Technology, Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki-Machi, Takasaki, Gunma 370-1292 (Japan); Kobayashi, Tomohiro [Advanced Science Institute, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 350-0198 (Japan); Kamiya, Tomihiro [Department of Advanced Radiation Technology, Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki-Machi, Takasaki, Gunma 370-1292 (Japan)

    2013-07-01

    Polytetrafluoroethylene (PTFE) is a typical fluoropolymer and it has several desirable technological properties such as electrical insulation, solid lubrication etc. However, the conventional microstructuring methods have not been well applied to PTFE due to its chemical inertness. Some effective micromachining using synchrotron radiation or ion beam irradiation has been reported. In this study, we create micro-prominences by raising the original surface using proton beam writing (PBW) without chemical etching. A conical prominence was formed by spiral drawing from the center with a 3 MeV proton beam. The body was porous, and the bulk PTFE below the prominence changed to fragmented structures. With decreasing writing speed, the prominence became taller but the height peaked. The prominence gradually reduced in size after the speed reached the optimum value. We expect that these porous projections with high aspect ratio will be versatile in medical fields and microelectromechanical systems (MEMS) technology.

  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. Engineering based assessment for a shape design of a pediatric ePTFE pulmonary conduit valve.

    Science.gov (United States)

    Tsuboko, Yusuke; Shiraishi, Yasuyuki; Yamada, Akihiro; Yambe, Tomoyuki; Miura, Hidekazu; Mura, Seitaro; Yamagishi, Masaaki

    2016-08-01

    The authors examined the hemodynamic characteristics of expanded polytetrafluoroethylene (ePTFE) pulmonary valved conduits quantitatively by our originally developed pediatric pulmonary mechanical circulatory system, in order to suggest the optimal shape design. The system consisted of pneumatically driven right atrium and ventricle model, a pulmonary valve chamber, and elastic pulmonary compliance model with peripheral vascular resistance units, a venous reservoir. We employed two different types of ePTFE valve and evaluated the relationship between the leaflets motion and hemodynamic characteristics by using a high-speed video camera. As a result, we successfully reproduced hemodynamic simulations in our pediatric pulmonary mock system. We confirmed that the presence of bulging sinuses in the pulmonary valved conduit reduced the transvalvular energy loss and increased the valve opening area during systolic period. Our engineering-based in vitro analysis could be useful for proposing a shape design optimization of sophisticated pediatric ePTFE pulmonary valve.

  13. Molecular level analyses of mechanical properties of PTFE sterilized by Co-60 γ-ray irradiation for clinical use

    Science.gov (United States)

    Furuta, Masakazu; Matsugaki, Aira; Nakano, Takayoshi; Hirata, Isao; Kato, Koichi; Oda, Takashi; Sato, Mamoru; Okazaki, Masayuki

    2017-10-01

    Recently, Co-60 gamma-ray irradiation has become markedly popular for the sterilization of biomedical materials, including expanded PTFE. However, its effect on the properties of PTFE has not been thoroughly examined. In this study, changes in the properties of PTFE before and after irradiation were analyzed physicochemically and discussed crystallographically. The tensile breaking strengths of PTFE decreased markedly on irradiation at 1 kGy, and were maintained at almost one fourth of the original value (44.3±2.5 N/mm2) ranging from 5 to 100 kGy. XPS analysis indicated that the atomic concentrations of carbon (C) and fluorine (F) of PTFE were not different among samples irradiated at various dosages. Raman spectra of PTFE showed a slight increase of the absorption peak intensity at 735 cm-1 in an irradiation dosage-dependent manner. X-ray diffraction showed that the crystal size of PTFE (56.7±1.0 nm) became smaller after radiation at 100 kGy (48.5±0.6 nm). These results are consistent with the above results of Raman analysis. It is suggested that the observed changes in the mechanical properties of PTFE may be due to nano-scale C-C bond scission by gamma ray irradiation, and not due to the formation of micro-scale cracks.

  14. Radiation syntheses and characteristics of PTFE-g-PSSA ion exchange membranes for applications in vanadium redox battery

    International Nuclear Information System (INIS)

    Peng Jinfen; Qiu Jinyi; Zhai Maolin; Xu Peng; Peng Jing; Li Jiuqiang; Wei Genshuan

    2006-01-01

    Radiation-induced grafting of styrene onto polyterafluorothylene (PTFE) films was studied by simultaneous irradiation technique. The grafting was induced by 60 Co γ-rays at room temperatures. Effects of the solvent, absorbed dose, dose rate, atmosphere and initial monomer concentration on the grafting yield were investigated and optimal grafting conditions were obtained. Subsequently, sulphonation of the grafted PTFE films (PTFE-g-PS) was investigated and a series of ion exchange membranes (PTFE-g-PSSA) was prepared. FTIR, TGA, XRD and SEM measurements showed that grafting and sulfonation of the PTFE films were successfully carried out; moreover, grafting of styrene mainly occurred in the pores of PTFE films and crystallization degree of the PTFE films decreased with increase grafting yield. Water uptake, ion exchange capacity (IEC) and conductivity of the PTFE-g-PSSA membrane increased with the grafting yield. The results indicated that by 20 kGy irradiation, ion exchange membrane which was suitable for vanadium redox battery can be prepared. (authors)

  15. Wear and friction performance of PTFE filled epoxy composites with a high concentration of SiO2 particles

    NARCIS (Netherlands)

    Shen, J.T.; Top, M.; Pei, Y.T.; de Hosson, Jeff

    2015-01-01

    In this work, the tribological performance of PTFE filled SiO2 particles–epoxy composites is investigated. Under a load of 60 N (~140 MPa contact pressure), the optimum content of PTFE lies between 10 and 15 wt%, which yields an ultralow coefficient of friction (CoF) in conjunction with a low wear

  16. Preparation and characterization of PTFE coating in new polymer quartz piezoelectric crystal sensor for testing liquor products

    International Nuclear Information System (INIS)

    Gu Yu; Li Qiang

    2015-01-01

    A new method was developed based on the electron beam vacuum dispersion (EBVD) technology to prepare the PTFE polymer coating of the new polymer quartz piezoelectric crystal sensor for testing liquor products. The new method was applied in the new EBVD equipment which we designed. A real-time system monitoring the polymer coating’s thickness was designed for the new EBVD equipment according to the quartz crystal microbalance (QCM) principle, playing an important role in preparing stable and uniform PTFE polymer coatings of the same thickness. 30 pieces of PTFE polymer coatings on the surface of the quartz crystal basis were prepared with the PTFE polymer ultrafine powder (purity ≥ 99.99%) as the starting material. We obtained 30 pieces of new PTFE polymer sensors. By using scanning electron microscopy (SEM), the structure of the PTFE polymer coating’s column clusters was studied. One sample from the 30 pieces of new PTFE polymer sensors was analysed by SEM in four scales, i.e., 400×, 1000×, 10000×, and 25000×. It was shown that under the condition of high bias voltage and low bias current, uniformly PTFE polymer coating could be achieved, which indicates that the new EBVD equipment is suitable for mass production of stable and uniform polymer coating. (paper)

  17. A fine surface roughness electroless Ni–P–PTFE composite modified stamper for light guide plate application

    International Nuclear Information System (INIS)

    Pan, K; Fu, C

    2010-01-01

    Electroless Ni–P–PTFE composite coating technology takes advantage of the beneficial properties from both Ni–P alloy and PTFE, such as good wear resistance, good anti-adhesion, dry lubrication, low coefficient of friction and good corrosion resistance. It has been applied in many mold industries. However, the Ni–P–PTFE composite coating suffers from bad surface roughness, when the PTFE particles incorporate into a Ni–P matrix. This severely hampers the technology to be applied to optical grade applications. In this paper, we propose a trick to generate a fine surface roughness (FSR) electroless Ni–P–PTFE composite to modify a nickel stamper. Using this new method, the nickel stamper can be covered by a Ni–P–PTFE functional layer and can keep the original surface property at the same time, namely the optical properties. We have chosen 4.5 inch (97 mm × 59 mm × 0.6 mm) light guide plates (LGPs) to demonstrate the effectiveness of the procedure. For the sake of comparison, the LGPs were produced by injection molding with three kinds of stampers including an original SUS430 master, an electroless Ni–P–PTFE composite coated nickel stamper and an FSR electroless Ni–P–PTFE composite modified stamper. We measured and discussed the optical performances at both the element level and system level, namely complete back light units.

  18. Wettability properties of PTFE/ZnO nanorods thin film exhibiting UV-resilient superhydrophobicity

    International Nuclear Information System (INIS)

    Bayat, A.; Ebrahimi, M.; Nourmohammadi, A.; Moshfegh, A.Z.

    2015-01-01

    Highlights: • Thin layer of Teflon was deposited on ZnO nanorods using RF sputtering technique. • Water contact angle was measured from 3° for ZnO to 160° for the PTFE/ZnO. • Very low contact angle hysteresis of ∼2° and sliding angle of ∼1° was measured. • Excellent stability under UV illumination was observed for the PTFE/ZnO sample. • We have proposed a model to describe wettability property supporting our data. - Abstract: In this research, initially anodization process was used to fabricate ZnO nanorods on Zn substrate and then RF sputtering technique was applied to grow a thin layer of polytetrafluoroethylene (PTFE, Teflon) on the coated ZnO nanorods for producing a superhydrophobic surface. According to scanning electron microscopy (SEM) observations, ZnO nanorods were formed with average diameter and length of about ∼180 nm and 14 μm, respectively. Superhydrophilic property of ZnO nanorods and superhydrophobic property of PTFE/ZnO nanorods was investigated by water contact angle (WCA) measurements. It was found that the contact angle varied with the PTFE deposition time. The highest contact angle measurement was obtained at 160° for the PTFE (60 min coating)/ZnO as optimum sample which indicates its superhydrophobic property. X-ray photoelectron spectroscopy (XPS) determined surface chemical composition and F/C ratio of about 1.27 for this sample. A change of water contact angle from 3° to 160° indicates transition from superhydrophilic to superhydrophobic state. Very low contact angle hysteresis (CAH) of ∼2° and sliding angle (SA) of ∼1° as well as unchanged contact angle under UV illumination was observed for the synthesized optimum PTFE/ZnO sample exhibits an excellent superhydrophobic property. Based on our data analysis, the ZnO nanorods and the PTFE/ZnO nanorods obey Wenzel and Cassie–Baxter model, respectively

  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. 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.

  1.  Evaluation of the humoral and cellular immune responses after implantation of a PTFE vascular prosthesis.

    Science.gov (United States)

    Skóra, Jan; Pupka, Artur; Dorobisz, Andrzej; Barć, Piotr; Korta, Krzysztof; Dawiskiba, Tomasz

    2012-07-02

    The experiment was designed in order to determine the immunological processes that occur during the healing in synthetic vascular grafts, especially to establish the differences in the location of the complement system proteins between the proximal and distal anastomosis and the differences in the arrangement of inflammatory cells in those anastomoses. The understanding of those processes will provide a true basis for determining risk factors for complications after arterial repair procedures. The experiment was carried out on 16 dogs that underwent implantation of unilateral aorto-femoral bypass with expanded polytetrafluoroethylene (ePTFE). After 6 months all animals were euthanized to dissect the vascular grafts. Immunohistochemical assays and electron microscopic examinations were performed. Immunohistochemical findings in the structure of neointima between anastomoses of vascular prostheses demonstrated significant differences between humoral and cellular responses. The area of proximal anastomosis revealed the presence of fibroblasts, but no macrophages were detected. The histological structure of the proximal anastomosis indicates that inflammatory processes were ended during the prosthesis healing. The immunological response obtained in the distal anastomosis corresponded to the chronic inflammatory reaction with the presence of macrophages, myofibroblasts and deposits of complement C3. The identification of differences in the presence of macrophages and myofibroblasts and the presence of the C3 component between the anastomoses is the original achievement of the present study. In the available literature, no such significant differences have been shown so far in the humoral and cellular immune response caused by the presence of an artificial vessel in the arterial system.

  2. Tl response of KMgF{sub 3}: Lu + PTFE at ultraviolet radiation; Respuesta Tl de KMgF{sub 3}: Lu + PTFE a radiacion ultravioleta

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, P R [Instituto Nacional de Investigaciones Nucleares, A.P. 18 -1027, 11801 Mexico D.F. (Mexico); Alarcon, N G [Facultad de Quimica, Universidad Autonoma del Estado de Mexico. Paseo Tollocan, Esq. con Jesus Carranza, 50180 Toluca, Estado de Mexico (Mexico); Furetta, C; Azorin, J [Universidad Autonoma Metropolitana- Iztapalapa, San Rafael Atlixco 186, 09340 Mexico. D.F. (Mexico)

    2003-07-01

    Ionizing radiation has different types of interaction with a crystalline solid. However, only few effects are interesting to optimize some thermoluminescent (Tl) properties of certain Tl materials. This paper presents results obtained by irradiating KMgF{sub 3}: Lu + Ptfe Tl dosimeters with ultraviolet (UV) radiation previously exposed to gamma radiation. These results showed that those dosimeters not exposed previously to gamma radiation did not presented any Tl signal. Meanwhile, those previously submitted to gamma irradiation showed that their sensitivity was increased as the gamma dose increased. The glow curve of sensitized KMgF{sub 3}: Lu + Ptfe exposed to UV radiation, presented the dosimetric pea at 212 C. This makes this material to be promissory for measuring UV radiation. (Author)

  3. Dosimetric characterization of KMgF{sub 3}:Tb+PTFE; Caracterizacion dosimetrica de KMgF{sub 3}:Tb+PTFE

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez R, M. I.; Garcia S, L.; Villicana M, M.; Huirache A, R.; Apolinar C, J. [Universidad Michoacana de San Nicolas de Hidalgo, Facultad de Ingenieria Quimica, Francisco J. Mujica s/n, Ciudad Universitaria, Col. Felicitas del Rio, 58030 Morelia, Michoacan (Mexico); Gonzalez M, P. R., E-mail: itcraf_15@hotmail.com [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2017-10-15

    In this work the results obtained from the dosimetric characterization of the new radiation detectors of KMgF{sub 3}:Tb+PTFE are presented. The host salt was obtained by means of the microwave technique, with the polycrystalline powder obtained, dosimeters were made in tablet form, using as Ptfe binder. The thermoluminescent response of these new detectors presented a linear behavior, in the dose range between 1 and 1000 Gy of {sup 60}Co gamma radiation, the reproducibility test in the measurements, during ten cycles of heat treatment, irradiation and reading presented ± 3.7% Ds, in the stability test of thermoluminescent signal, during two months showed that the fading is practically null. Due to the results obtained, this new detector could be very useful for the dosimetry of ionizing radiation in different clinical applications. (Author)

  4. Containment vessel

    International Nuclear Information System (INIS)

    Zbirohowski-Koscia, K.F.; Roberts, A.C.

    1980-01-01

    A concrete containment vessel for nuclear reactors is disclosed that is spherical and that has prestressing tendons disposed in first, second and third sets, the tendons of each set being all substantially concentric and centred around a respective one of the three orthogonal axes of the sphere; the tendons of the first set being anchored at each end at a first anchor rib running around a circumference of the vessel, the tendons of the second set being anchored at each end at a second anchor rib running around a circumference of the sphere and disposed at 90 0 to the first rib, and the tendons of the third set being anchored some to the first rib and the remainder to the second rib. (author)

  5. Tribological study of PTFE composites loaded with porcelain tile waste; Estudo tribologico de compositos de PTFE carregados com rejeito de porcelanato

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, P.M.; Araujo Neto, A.P.; Souza, J.R.; Medeiros, J.T.N., E-mail: plinio_rpg@hotmail.com [Universidade Federal do Rio Grande do Norte (GET/UFRN), Natal, RN (Brazil). Grupo de Estudos de Tribologia e Integridade Estrutural

    2016-07-01

    The Brazilian northeast is one of the largest producers of clays that burn in the white form and disposal of tailings from the process of polishing the ceramic pieces of porcelain stands out as a major source of environmental degradation. This problem can be reduced by adding such material as filler in composites, in order to improve the mechanical properties of the polymeric matrix. Polytetrafluoroethylene (PTFE) is characterized as a good solid lubricant, because it has excellent properties such as low coefficient of friction (0.01 < μ < 0.1), thermal stability at high temperatures and chemical resistance. However, the pure PTFE has high wear rates (greater than 10-13m2/N) leading to early failures of various components. To reuse the Tailings of Porcelain (TP), composites of PTFE + TP were developed in three different compositions (85:15, 75:25 and 65:35). For this investigation the particle size distribution and some chemical characteristics of the tailings by testing XRD, XRF, SEM and EDS were performed, registering a large amount of silica, aluminum and other metals. Roughness, wettability and sclerometry also were performed. It was noted that the values of arithmetic average roughness, Ra, is higher for composites with higher percentage of TP, in addition they have a lower contact angle and higher surface energy to distilled water, characterized as hydrophilic. The results of energy of deformation provided by the sclerometry test were non-linear. (author)

  6. Anatomic changes of target vessels after fenestrated and branched aortic aneurysm repair.

    Science.gov (United States)

    Kalder, J; Keschenau, P; Tamm, M; Jalaie, H; Jacobs, M J; Greiner, A

    2014-04-01

    Objective of this study was to evaluate the anatomic changes of the stented target vessels after endovascular repair of complex aortic aneurysms. Between July 2011 and December 2013, 53 aortic aneurysms were treated in our department with fenestrated and branched stent-graft devices. Forty-two of these patients were pre- and postoperatively scanned with a high resolution computer tomography (CT) (Cook Zenith® fenestrated or branched, Australia Pty. Ltd., Brisbane, Australia: N.=19; AnacondaTM fenestrated, Vascutek, Glasgow, Scotland, UK: N.=23). The other 11 out of the 53 patients did not receive a CT scan, because of a pre-existing renal failure. In the CT scans we retrospectively evaluated the anatomic vessel deviation at the origin of the target vessel and the vessel shift distal to the stent. For the first measurement the CT scans were loaded into OsiriX MD®, and the pre- and postoperative angles of the target vessels were measured and subtracted. For matching, the CT-scans were normalized at vertebral body lumbar 2. The second measured angle was the maximal measured angle distal to the target vessel stent-graft. Altogether, 113 target vessels were stented (celiac trunk [CT] 15, superior mesenteric arteries [SMA] 26, renal arteries [RA] 72), with 97 balloon-expandable PTFE stents: 90 Atrium V12 (Maquet Getinge group, Hudson, NH, USA), 7 BeGrafts (Bentley InnoMed, Hechingen, Germany) and 16 self-expandable fluency PTFE stents (Bard, Karlsruhe, Germany). The mean anatomic deviation at the target vessel origin was 28±17.3 and the mean vessel shift distal to the stent was 36.3±18.8. There were no significant differences between the main device and the target vessel stent types. Fenestrated and branched stent-graft solutions for aortic aneurysm repair induce changes of the target vessel anatomy. We did not observe significant differences between the several devices.

  7. Optimization for Tribological Properties of Glass Fiber-Reinforced PTFE Composites with Grey Relational Analysis

    Directory of Open Access Journals (Sweden)

    Firojkhan Pathan

    2016-01-01

    Full Text Available Most recent history shows that polytetrafluoroethylene (PTFE is widely used as antifrictional materials in industry for wide speed range. A high antifriction property of PTFE makes it suitable for dry friction bearing. Main disadvantage of using PTFE is its high wear rate, so extensive research had been carried out to improve the wear resistance with addition of filler material. This study focuses on four input parameters load, sliding speed, sliding distance, and percentage of glass fiber as a filler material. Taguchi method was used for experimentation; each parameter is having 3 levels with L27 orthogonal array. Grey relational analysis is used to convert multiple response parameters, namely, wear and coefficient of friction, into single grey relation grade. The optimal input parameters were selected based on the S/N ratio. It was observed that load 3 kg, sliding speed 5.1836 m/s (900 rpm, sliding distance 2 km, and 15% of glass fiber are optimal input parameters for PTFE without significantly affecting the wear rate and coefficient of friction.

  8. Dacron or PTFE for Above-knee Femoropopliteal Bypass. A Multicenter Randomised Study

    DEFF Research Database (Denmark)

    Jensen, L. P.; Lepäntalo, M.; Fossdal, J. E.

    2007-01-01

    more often than patients operated on for intermittent claudication, 10 and 3 respectively (p=0.003), and had higher mortality rates, 20% and 8% respectively (p=0.001). CONCLUSION: This trial confirms that Dacron is at least as durable as PTFE for above-knee bypass procedures, and might even be superior....

  9. Effect of gamma radiation on dielectric and mechanical properties of modified fluoroplastic PTFE

    Science.gov (United States)

    Romanov, Boris; Kostromin, Valeriy; Bedenko, Sergey; Knyshev, Vladimir; Mukhnurov, Ilya; Matias, Rodrigo Roman

    2018-03-01

    The influence of gamma radiation on dielectric and mechanical characteristics of modified fluoroplast PTFE-4 MBK is considered in this paper. The material was exposed to Gamma-ray source GU-200 (Joint-stock company «Research Institute of Instruments», Lytkarino, Russia). The results of the research have shown that the relative permittivity and the tangent of the dielectric loss angle of PTFE-4 MBK samples at doses 4.105-1.106 Gy monotonically increase by 2.9 and 9.4%, respectively, compared to un-exposed material. The research of the mechanical properties of PTFE-4 MBK showed a maximum stress of up to 13.8 MPa and a maximum strain of 252% at doses of 8.104 Gy. It has been demonstrated that modified PTFE-4 MBK has good dielectric characteristics and withstanding high mechanical stress. We propose to use the results of the research for choosing cables and wiring location used in nuclear and space industry.

  10. PTFE effect on the electrocatalysis of the oxygen reduction reaction in membraneless microbial fuel cells.

    Science.gov (United States)

    Guerrini, Edoardo; Grattieri, Matteo; Faggianelli, Alessio; Cristiani, Pierangela; Trasatti, Stefano

    2015-12-01

    Influence of PTFE in the external Gas Diffusion Layer (GDL) of open-air cathodes applied to membraneless microbial fuel cells (MFCs) is investigated in this work. Electrochemical measurements on cathodes with different PTFE contents (200%, 100%, 80% and 60%) were carried out to characterize cathodic oxygen reduction reaction, to study the reaction kinetics. It is demonstrated that ORR is not under diffusion-limiting conditions in the tested systems. Based on cyclic voltammetry, an increase of the cathodic electrochemical active area took place with the decrease of PTFE content. This was not directly related to MFC productivity, but to the cathode wettability and the biocathode development. Low electrodic interface resistances (from 1 to 1.5 Ω at the start, to near 0.1 Ω at day 61) indicated a negligible ohmic drop. A decrease of the Tafel slopes from 120 to 80 mV during productive periods of MFCs followed the biological activity in the whole MFC system. A high PTFE content in the cathode showed a detrimental effect on the MFC productivity, acting as an inhibitor of ORR electrocatalysis in the triple contact zone.

  11. Removal of I, Rn, Xe and Kr from off gas streams using PTFE membranes

    Science.gov (United States)

    Siemer, Darryl D.; Lewis, Leroy C.

    1990-01-01

    A process for removing I, R, Xe and Kr which involves the passage of the off gas stream through a tube-in-shell assembly, whereby the tubing is a PTFE membrane which permits the selective passages of the gases for removing and isolating the gases.

  12. Surface modification of BMN particles with silane coupling agent for composites with PTFE

    Science.gov (United States)

    Qi, Yanyuan; Luo, Qing; Shen, Jie; Zheng, Liu; Zhou, Jing; Chen, Wen

    2017-08-01

    Polymer-ceramic dielectric composites, which possess better dielectric properties, flexibility, ease in processing and shaping since they combine the advantages of polymers and dielectric ceramics, are widely used in microwave substrate applications. In order to optimize the properties of the composites, it is necessary to enhance the compatibility between the polymer matrix and ceramic filler because of their tremendous difference. In this paper, the vinyltrimethoxysilane (VTMS) is used to modify the Ba(Mg1/3Nb2/3)O3 (BMN) ceramic particles which can improve the compatibility between BMN ceramics and PTFE and the distribution of BMN in polytetrafluoroethylene (PTFE). The modification of VTMS has no influence on the crystal structure of BMN ceramics and the compact VTMS modified BMN/PTFE composites with satisfactory uniformity and less cavities are obtained. The relative permittivity (εr) of VTMS modified BMN/PTFE composite substrate is 5.84 while the loss tangent reaches 1.5 × 10-3 at microwave frequencies (around 10 GHz).

  13. Use of PTFE patch for pericardial closure after minimal invasive LVAD implantation.

    Science.gov (United States)

    Mohite, Prashant N; Sabashnikov, Anton; Popov, Aron F; Fatullayev, Javid; Simon, André R

    2016-07-01

    The left ventricular assist device (LVAD) is now a routine therapy for advanced heart failure. The thoracotomy approach for LVAD implantation, in which the left ventricle is approached through a pericardial rent, is becoming popular. We demonstrate closure of the pericardial rent with a polytetrafluoroethylene (PTFE) patch and its advantages. © The Author(s) 2015.

  14. Modeling the constitutive and frictional behavior of PTFE flexible stamps for nanoimprint lithography

    DEFF Research Database (Denmark)

    Sonne, Mads Rostgaard; Hattel, Jesper Henri

    2013-01-01

    was verified through an experiment, where a PTFE sheet was deformed by a steel sphere mounted in a tensile test machine. Good agreement between simulations and experimental results is found, both regarding force–displacement and corresponding principal strain measurements. As expected, applying the correct...

  15. PTFE treatment by remote atmospheric Ar/O2 plasmas : a simple reaction scheme model proposal

    NARCIS (Netherlands)

    Carbone, E.A.D.; Verhoeven, M.W.G.M.; Keuning, W.; van der Mullen, J.J.A.M.

    2016-01-01

    Polytetrafluoroethylene (PTFE) samples were treated by a remote atmospheric pressure microwave plasma torch and analyzed by water contact angle (WCA) and X-ray photoelectron spectroscopy (XPS). In the case of pure argon plasma a decrease of WCA is observed meanwhile an increase of hydrophobicity was

  16. 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

  17. Does patency after a vein collar and PTFE-bypass depend on sex and age?

    DEFF Research Database (Denmark)

    Lundgren, F; Schroeder, Torben Veith

    2012-01-01

    Randomized studies evaluating the effect of a vein collar at the distal anastomosis of PTFE-grafts show conflicting results. The study of the Joint Vascular Research Group (JVRG) of UK found improved primary patency while the Scandinavian Miller Collar Study (SCAMICOS) found neither any effect...

  18. Gas barrier properties of diamond-like carbon films coated on PTFE

    International Nuclear Information System (INIS)

    Ozeki, K.; Nagashima, I.; Ohgoe, Y.; Hirakuri, K.K.; Mukaibayashi, H.; Masuzawa, T.

    2009-01-01

    Diamond-like carbon (DLC) films were deposited on polytetrafluoroethylene (PTFE) using radio frequency (RF) plasma-enhanced chemical vapour deposition (PE-CVD). Before the DLC coating, the PTFE substrate was modified with a N 2 plasma pre-treatment to enhance the adhesive strength of the DLC to the substrate. The influences of the N 2 plasma pre-treatment and process pressure on the gas permeation properties of these DLC-coated PTFE samples were investigated. In the Raman spectra, the G peak position shifted to a lower wave number with increasing process pressure. With scanning electron microscopy (SEM), a network of microcracks was observed on the surface of the DLC film without N 2 plasma pre-treatment. The density of these cracks decreased with increasing process pressure. In the film subjected to a N 2 plasma pre-treatment, no cracks were observed at any process pressure. In the gas barrier test, the gas permeation decreased drastically with increasing film thickness and saturated at a thickness of 0.2 μm. The DLC-coated PTFE with the N 2 plasma pre-treatment exhibited a greater reduction in gas permeation than did the samples without pre-treatment. For both sample types, gas permeation decreased with increasing process pressure.

  19. Tribological behavior of Nano-Al2O3 and PEEK reinforced PTFE composites

    Science.gov (United States)

    Wang, Banghan; Lv, Qiujuan; Hou, Genliang

    2017-01-01

    The Nano-Al2O3 and PEEK particles synergetic filled PTFE composites were prepared by mechanical blending-molding-sintering method. The tribological behavior of composites with different volume fraction of fillers was tested on different test conditions by a MMW-1A block-on-ring friction and wear tester. The transfer film on counterpart 5A06 Aluminum alloy ring was inspected and anslyzed with scanning electronic microscopy (SEM) and X-ray diffraction (XRD). The results demonstrated that the lowest friction coefficient was gained when the PTFE composite was filled with only 10% PEEK. The friction coefficient decreases gradually with the increasing content of PEEK. The special wear rate of 10% PEEK/PTFE were decreased clearly with filled different contents of nano-Al2O3 particles. The special wear rate of the sample with 5% nano-Al2O3 and 10% PEEK had the lowest volume wear rate. The sliding speed effect significantly on the tribological behavior of nano-Al2O3/PEEK/PTFE composites.

  20. Spray-coating process in preparing PTFE-PPS composite super-hydrophobic coating

    Directory of Open Access Journals (Sweden)

    Rui Weng

    2014-03-01

    Full Text Available In order to improve the performance of a liquid-floated rotor micro-gyroscope, the resistance of the moving interface between the rotor and the floating liquid must be reduced. Hydrophobic treatment can reduce the frictional resistance between such interfaces, therefore we proposed a method to prepare a poly-tetrafluoroethylene (PTFE-poly-phenylene sulphide (PPS composite super-hydrophobic coating, based on a spraying process. This method can quickly prepare a continuous, uniform PTFE-PPS composite super-hydrophobic surface on a 2J85 material. This method can be divided into three steps, namely: pre-treatment; chemical etching; and spraying. The total time for this is around three hours. When the PTFE concentration is 4%, the average contact angle of the hydrophobic coating surface is 158°. If silicon dioxide nanoparticles are added, this can further improve the adhesion and mechanical strength of the super-hydrophobic composite coating. The maximum average contact angle can reach as high as 164° when the mass fraction of PTFE, PPS and silicon dioxide is 1:1:1.

  1. Spray-coating process in preparing PTFE-PPS composite super-hydrophobic coating

    Science.gov (United States)

    Weng, Rui; Zhang, Haifeng; Liu, Xiaowei

    2014-03-01

    In order to improve the performance of a liquid-floated rotor micro-gyroscope, the resistance of the moving interface between the rotor and the floating liquid must be reduced. Hydrophobic treatment can reduce the frictional resistance between such interfaces, therefore we proposed a method to prepare a poly-tetrafluoroethylene (PTFE)-poly-phenylene sulphide (PPS) composite super-hydrophobic coating, based on a spraying process. This method can quickly prepare a continuous, uniform PTFE-PPS composite super-hydrophobic surface on a 2J85 material. This method can be divided into three steps, namely: pre-treatment; chemical etching; and spraying. The total time for this is around three hours. When the PTFE concentration is 4%, the average contact angle of the hydrophobic coating surface is 158°. If silicon dioxide nanoparticles are added, this can further improve the adhesion and mechanical strength of the super-hydrophobic composite coating. The maximum average contact angle can reach as high as 164° when the mass fraction of PTFE, PPS and silicon dioxide is 1:1:1.

  2. Characterization of the personal thermoluminescent dosemeter of LiF: Mg, Ti + Ptfe

    International Nuclear Information System (INIS)

    Azorin N, J.; Gutierrez C, A.; Gonzalez M, P.

    1991-01-01

    The objective of this work is to characterize the thermoluminescent dosemeters taken place in the laboratory in form of pellets of LiF: Mg, Ti + Ptfe like personal dosemeters, subjecting them to the operation tests proposed by the international standards and comparing them with the TLD-100, the Tl dosemeter more used at the moment for personal dosimetry

  3. Determination of the parameters of traps in thermoluminescent dosemeters of ZrO2: Eu + Ptfe

    International Nuclear Information System (INIS)

    Nieto H, B.; Azorin N, J.; Rivera M, T.

    2002-01-01

    In this work the manufacture of dosemeters in pellets form of ZrO 2 : Eu + Ptfe is described; which after were exposed to UV radiation (260 nm) were generated the corresponding thermoluminescent curves and in the basis to the properties of symmetry of the curves it was determined the kinetic order using the Chen and the Balarin criteria. (Author)

  4. Experimental Study on Reaction Characteristics of PTFE/Ti/W Energetic Materials under Explosive Loading

    Directory of Open Access Journals (Sweden)

    Yan Li

    2016-11-01

    Full Text Available Metal/fluoropolymer composites represent a new category of energetic structural materials that release energy through exothermic chemical reactions initiated under shock loading conditions. This paper describes an experiment designed to study the reaction characteristics of energetic materials with low porosity under explosive loading. Three PTFE (polytetrafluoroethylene/Ti/W mixtures with different W contents are processed through pressing and sintering. An inert PTFE/W mixture without reactive Ti particles is also prepared to serve as a reference. Shock-induced chemical reactions are recorded by high-speed video through a narrow observation window. Related shock parameters are calculated based on experimental data, and differences in energy release are discussed. The results show that the reaction propagation of PTFE/Ti/W energetic materials with low porosity under explosive loading is not self-sustained. As propagation distance increases, the energy release gradually decreases. In addition, reaction failure distance in PTFE/Ti/W composites is inversely proportional to the W content. Porosity increased the failure distance due to higher shock temperature.

  5. Thermoluminescent characteristics of CaSO4:Dy+PTFE irradiated with high energy electron beams

    International Nuclear Information System (INIS)

    Alvarez, R.; Rivera, T.; Calderon, J. A.; Jimenez, Y.; Rodriguez, J.; Oviedo, O.; Azorin, J.

    2011-10-01

    In the present work thermoluminescent response of dysprosium doped calcium sulfate embedded in polytetrafluorethylene (CaSO 4 :Dy+PTFE) under high electron beam irradiations from linear accelerator for clinical applications was investigated. The irradiations were carried out using high electron beams (6 to 18 MeV) from a linear accelerator Varian, C linac 2300C/D, for clinical practice purpose. The electron irradiations were obtained by using the water solid in order to guarantee electronic equilibrium conditions. Field shaping for electron beams was obtained with electron cones. Glow curve and other thermoluminescent characteristics of CaSO 4 :Dy+PTFE were conducted under high electron beams irradiations. The thermoluminescent response of the pellets showed and intensity peak centered at around 235 C. Thermoluminescent response of CaSO 4 :Dy+PTFE as a function of high electron absorbed dose showed a linearity in a wide range. To obtain reproducibility characteristic, a set of pellets were exposed repeatedly for the same electron absorbed dose. The results obtained in this study can suggest the applicability of CaSO 4 :Dy+PTFE pellets for high electron beam dosimetry, provided fading is correctly accounted for. (Author)

  6. [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

  7. Indirect induction of endothelial cell injury by PU- or PTFE-mediated activation of monocytes.

    Science.gov (United States)

    Liu, Xin; Xue, Yang; Sun, Jiao

    2010-01-01

    Polyurethanes (PUs) and polytetrafluoroethylene (PTFE) are widely used for making cardiovascular devices, but thrombus formation on the surfaces of these devices is inevitable. Since endothelial injury can lead to thrombosis, most of the studies on PUs or PTFE focused on their damage to endothelial cells. However, few studies have attempted to clarify whether the use of foreign objects as biomaterials can cause endothelial injury by activating the innate immune system. In this study, we aimed to investigate the roles of PU- or PTFE-stimulated immune cells in endothelial-cell injury. First, monocytes (THP-1 cells) were stimulated with PU or PTFE for 24 h and, subsequently, human umbilical vein endothelial cells (HUVECs) were treated with the supernatants of the stimulated cells for 24 h. We measured the generation of intracellular reactive oxygen species (ROS) from THP-1 cells treated with PU and PTFE for 24 h, meanwhile hydrogen dioxide (H(2)O(2)), tumor necrosis factor (TNF)-α and interleukin (IL)-1β in the supernatants were also detected. Then, we assessed the apoptosis rate of the HUVECs and determined the expression of NO, inducible nitric oxide synthase (iNOS), and apoptosis-related proteins (p53, Bax, Bcl-2) in the HUVECs. The results showed that large amounts of ROS and low levels of pro-inflammatory cytokines (TNF-α and IL-1β) were produced by the stimulated THP-1 cells. After culturing with the supernatants of the PU- or PTFE-stimulated THP-1 cells, the apoptosis rate, NO production and expression of iNOS, p53 and Bax in the HUVECs were up-regulated, while Bcl-2 expression was down-regulated. In conclusion, the release of ROS by PU- or PTFE-treated THP-1 cells may induce iNOS expression and cause apoptosis in HUVECs via the p53, Bax and Bcl-2 proteins. These data provide the interesting finding that endothelial injury in the process of biomaterial-induced thrombosis can be initiated through the release of soluble mediators by monocytes.

  8. Structure-property effects on mechanical, friction and wear properties of electron modified PTFE filled EPDM composite

    Directory of Open Access Journals (Sweden)

    2009-01-01

    Full Text Available Tribological properties of Ethylene-Propylene-Diene-rubber (EPDM containing electron modified Polytetrafluoroethylene (PTFE have been investiagted with the help of pin on disk tribometer without lubrication for a testing time of 2 hrs in atmospheric conditions at a sliding speed and applied normal load of 0.05 m•s–1 and FN = 1 N, respectively. Radiation-induced chemical changes in electron modified PTFE powders were analyzed using Electron Spin Resonance (ESR and Fourier Transform Infrared (FTIR specroscopy to characterize the effects of compatibility and chemical coupling of modified PTFE powders with EPDM on mechanical, friction and wear properties. The composites showed different friction and wear behaviour due to unique morphology, dispersion behaviour and radiation functionalization of PTFE powders. In general, EPDM reinforced with electron modified PTFE powder demonstrated improvement both in mechanical and tribological properties. However, the enhanced compatibility of PTFE powder resulting from the specific chemical coupling of PTFE powder with EPDM has been found crucial for mechanical, friction and wear properties.

  9. 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.

  10. Enhanced tribological behavior of anodic films containing SiC and PTFE nanoparticles on Ti6Al4V alloy

    International Nuclear Information System (INIS)

    Li, Songmei; Zhu, Mengqi; Liu, Jianhua; Yu, Mei; Wu, Liang; Zhang, Jindan; Liang, Hongxing

    2014-01-01

    Highlights: • An environmental friendly sodium tartrate (C 4 O 6 H 4 Na 2 ) electrolyte is used. • SiC and PTFE nanoparticles reduce friction coefficient of composite films. • SiC and PTFE nanoparticles demonstrate a favorable synergistic effect on improving tribological properties of composite films. • Lubricating mechanisms of SiC and PTFE nanoparticles are discussed. - Abstract: Anodic films containing SiC and polytetrafluoroethylene (PTFE) nanoparticles were successfully fabricated on Ti6Al4V alloy by using anodic oxidation method in an environmental friendly electrolyte. The morphology, structure and composition of the films were studied with the scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results showed that the film contained a layered structure and have a surface full of petaloid bulges, which was totally different from the common anodic oxide film of the porous kind. The tribological properties of the films were investigated with dry friction tests in terms of the friction coefficient, wear rate and the morphology of worn surfaces. The results indicated that the SiC/PTFE composite film exhibited much better anti-wear and anti-friction performances than that of the SiC composite film, the PTFE composite film and the ordinary film without nanoparticles. The SiC/PTFE composite film has friction coefficient of 0.1 and wear rate of 20.133 mg/m, which was decreased respectively by 80% and 44.5% compared with that of the ordinary film. The lubricating mechanisms of the composite film containing SiC and PTFE nanoparticles were discussed. PTFE nanoparticles could lead to the formation of lubricating layer while SiC nanoparticles inside the lubricating layer turned sliding friction to rolling friction

  11. PTFE grafts versus tunneled cuffed catheters for hemodialysis: which is the second choice when arteriovenous fistula is not feasible?

    Science.gov (United States)

    Donati, Gabriele; Cianciolo, Giuseppe; Mauro, Raffaella; Rucci, Paola; Scrivo, Anna; Marchetti, Antonio; Giampalma, Emanuela; Golfieri, Rita; Panicali, Laura; Iorio, Mario; Stella, Andrea; La Manna, Gaetano; Stefoni, Sergio

    2015-02-01

    Vascular access-related complications are still one of the leading causes of morbidity in hemodialysis patients. The aim of this study was to compare polytetrafluoroethylene (PTFE) grafts versus tunneled cuffed permanent catheters (TCCs) in terms of vascular access and patients' survival. An observational study was carried out with a 2-year follow-up. Eighty-seven chronic hemodialysis patients were enrolled: 31 with a PTFE graft as vascular access for hemodialysis versus 56 with a TCC. Patients' mean age was 63.8 ± 14.6 (grafts) versus 73.5 ± 11.3 years (TCCs), P = 0.001. Significantly more patients with TCC had atrial fibrillation than patients with grafts (30.3% versus 6.5%, P = 0.01). In an unadjusted Kaplan-Meier analysis, median TCC survival at 24 months was 5.4 months longer than that of PTFE grafts but not significantly (log-rank test = 1.3, P = ns). In a Cox regression analysis adjusted for age, gender, number of previous vascular accesses, diabetes, atrial fibrillation, smoking, and any complication, this lack of significant difference in survival of the vascular access between TCC and PTFE groups was confirmed and diabetes proved to be an independent risk factor for the survival of both vascular accesses considered (P = 0.02). In an unadjusted Kaplan-Meier analysis, a higher mortality was found in the TCC group than in the PTFE group at 24 months (log-rank test = 10.07, P PTFE grafts. When an arteriovenous fistula (AVF) is not possible, PTFE grafts can be considered the vascular access of second choice, whereas TCCs can be used when an AVF or PTFE graft are not feasible or as a bridge to AVF or PTFE graft creation. Copyright © 2014 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  12. Thermoluminescent response of CaSO{sub 4}: Dy + PTFE to beta particles; Respuesta termoluminiscente de CaSO{sub 4}: Dy + PTFE a particulas beta

    Energy Technology Data Exchange (ETDEWEB)

    Aguirre C, A.; Azorin N, J. [Colegio de Bachilleres No. 13, Xochimilco-Tepepan, 16000 Mexico D.F. (Mexico)

    2000-07-01

    In this work the results of studying the thermoluminescent properties of CaSO{sub 4}: Dy + PTFE are presented when it is irradiated with beta particles. The conclusion was the obtention of the Tl response curve in function of dose is that to desexcite the dosemeters at temperature 300 C during 30 minutes and after that were irradiated at different times in groups and to do the reading of dosemeter, it can be observed that a greater irradiation time major is the Tl response and this depends of the material has been used. (Author)

  13. Measurement of absorbed dose for high energy electron using CaSO4: Tm-PTFE TLD

    International Nuclear Information System (INIS)

    Park, Myeong Hwan; Kim, Do Sung

    2000-01-01

    In this study, the highly sensitive CaSO 4 : Tm-PTFE TLDs has been fabricated for the purpose of measurement of high energy electron. CaSO 4 : Tm phosphor powder was mixed with polytetrafluoroethylene(PTFE) powder and moulded in a disk type(diameter 8.5mm, thickness 90mg/cm 2 ) by cold pressing. The absorbed dose distribution and ranges for high energy electron were measured by using the CaSO 4 : Tm-PTFE TLDs. The ranges determined were R 100 =3D14.5mm, R 50 =3D24.1mm and R p =3D31.8mm, respectively and the beam flatness, the variation of relative dose in 80% of the field size, was 4.5%. The fabricated CaSO 4 : Tm-PTFE TLDs may be utilized in radiation dosimetry for personal, absorbed dose and environmental monitoring.=20

  14. SIMULATION OF POROSITY AND PTFE CONTENT IN GAS DIFFUSION LAYER ON PROTON EXCHANGE MEMBRANE FUEL CELL PERFORMANCE

    Directory of Open Access Journals (Sweden)

    NUR H. MASLAN

    2016-01-01

    Full Text Available Numerous research and development activities have been conducted to optimize the operating parameters of a proton exchange membrane fuel cell (PEMFC by experiments and simulations. This study explains the development of a 3D model by using ANSYS FLUENT 14.5 to determine the optimum PEMFC parameters, namely, porosity and polytetrafluoroethylene (PTFE content, in the gas diffusion layer (GDL. A 3D model was developed to analyze the properties and effects of GDL. Simulation results showed that the increase in GDL porosity significantly improved the performance of PEMFC in generating electrical power. However, the performance of PEMFC decreased with increasing PTFE content in GDL. Thus, the PTFE content in the GDL must be optimized and the optimum PTFE content should be 5 wt%. The model developed in this simulation showed good capability in simulating the PEMFC parameters to assist the development process of PEMFC design.

  15. Preliminary study of blood compatibility of PTFE copolymerized with DMAA through gamma rays compared to PET and aflon films

    International Nuclear Information System (INIS)

    Queiroz, A.A.A. de; Higa, O.Z.

    1990-01-01

    The new method developed by Imai and Nosa was used for the evaluation of blood compatibility of poly(tetrafluoroethylene) (PTFE) grafted films with N,N - dimethylacrylamide (DMAA). The amount of the formed thrombus was measured gravimetrically at an appropriate interval of time after calcium chloride being added to the ACD blood in contact to the tested material. It was concluded that the method of modifying the polymeric surface of PTFE by grafting the hydrophilic monomer DMAA improved its blood compatibility. (author)

  16. Microbiologic Evaluation of Cotton and Polytetrafluoroethylene (PTFE) Tape as Endodontic Spacer Materials in Primary Molars An in Vivo Study.

    Science.gov (United States)

    Prabhakar, Attiguppe Ramasetty; Dixit, Kratika; Raju, O S

    PTFE tape, which is commonly used as plumber's tape is an inorganic, non-fibrous, ribbon like material. The aim of this study was to evaluate PTFE tape as endodontic spacer material and to compare it with commonly used spacer material that is cotton, in primary teeth. Seventeen children undergoing pulpectomy of lower second primary molar bilaterally were included in the study. Cotton and PTFE tape were placed as spacers on each side randomly. Samples were taken from the access cavity at baseline and after seven days to check for microbial leakage. Spacer materials were also checked for microbial contamination. The results revealed that there was a significant increase in the bacterial colony count after seven days in cotton group. The access cavities were also positive for microbial leakage in the cotton group where the spacers showed positive growth. In PTFE group only two samples showed microbial contamination of spacer and out of two only one sample showed contamination of access cavity along with spacer. Within the limitations of this study, it can be concluded that PTFE tape performed better than cotton as endodontic spacer material. Thus, PTFE tape can be recommended as an endodontic spacer material as an alternative to cotton in primary teeth.

  17. Compressive Properties of PTFE/Al/Ni Composite Under Uniaxial Loading

    Science.gov (United States)

    Wang, Huai-xi; Li, Yu-chun; Feng, Bin; Huang, Jun-yi; Zhang, Sheng; Fang, Xiang

    2017-05-01

    To investigate the mechanical properties of pressed and sintered PTFE/Al/Ni (polytetrafluoroethylene/aluminum/nickel) composite, uniaxial quasi-static and dynamic compression experiments were conducted at strain rates from 10-2 to 3 × 103/s. The prepared samples were tested by an electrohydraulic press with 300 kN loading capacity and a split Hopkinson pressure bar (SHPB) device at room temperature. Experimental results show that PTFE/Al/Ni composite exhibits evident strain hardening and strain rate hardening. Additionally, a bilinear relationship between stress and {{log(}}\\dot{ɛ} ) is observed. The experimental data were fit to Johnson-Cook constitutive model, and the results are in well agreement with measured data.

  18. Relationship of Adhesive, Contact and Electret Properties of PTFE Modified by DC Discharge

    Science.gov (United States)

    Yablokov, M.; Piskarev, M.; Gilman, A.; Kechek'yan, A.; Kuznetsov, A.

    2018-02-01

    The relationship between the contact, adhesive and electret properties of PTFE films modified by direct current glow discharge has been studied. The film samples of 40 μm thickness were placed at the anode and cathode and treated in the air as a working gas. The contact properties of polymer surface were characterized by the values of deionized water contact angle. The peel strength was determined using T-peel test for the Scotch®810/PTFE film contact. The electret potential was measured by the compensation technique using dynamic capacitor, and from the measured potential value the effective surface charge density was calculated. It has been found that there is an undoubted correlation between the change in the value of water contact angle, the peel strength of the DC discharge-treated film, and the magnitude of the effective surface charge.

  19. Chemically robust carbon nanotube–PTFE superhydrophobic thin films with enhanced ability of wear resistance

    Institute of Scientific and Technical Information of China (English)

    Kewei Wang; Pan Xiong; Xiuping Xu; Kan Wang; YanLong Li; Yufeng Zheng

    2017-01-01

    A chemically robust superhydrophobic nanocomposite thin film with enhanced wear resistance is prepared from a composite comprising polytetrafluoroethylene (PTFE) and carbon nanotubes. The superhydrophobic thin films with hierarchical structure are fabricated by spraying an environmentally friendly aqueous dispersion containing carbon nanotubes and PTFE resin on silicon wafer. Thin films with a contact angle of 154.1° ± 2° and a sliding angle less than 2° remain superhydrophobic after abrading over 500 times under a pressure of 50 g/cm2. The thin film is also extremely stable even under much stress conditions. To further the understanding of the enhancement of wear resistance, we investigated the formation of microsized structure and their effects. The growth of microbumps is caused by attracting solution droplet to the hydrophilic islands on hydrophobic surface.

  20. Tribological properties of polymers PI, PTFE and PEEK at cryogenic temperature in vacuum

    Science.gov (United States)

    Wang, Qihua; Zheng, Fei; Wang, Tingmei

    2016-04-01

    The effects of temperature, sliding speed and load on the tribological properties of polyimide (PI), polytetrafluoroethylene (PTFE) and polyetheretherketone (PEEK) at cryogenic temperature in vacuum were investigated using a ball-on-disk tribometer. At cryogenic temperature, polymers show higher hardness which results in decreasing contact area between the friction pairs. Moreover, the real surface area in contact between steel ball and polymer disk determines the friction coefficient instead of the formation and adhesion of the transfer film. Thus, the friction coefficients at cryogenic temperatures are lower than at room temperature. On the other hand, wear rates of the three polymers decrease as temperature decreases since molecular mobility and migration are limited at cryogenic temperatures. For the visco-elasticity of PI, PTFE and PEEK, the friction coefficients fall as the load increases.

  1. Tl response of KMgF3: Lu + PTFE at ultraviolet radiation

    International Nuclear Information System (INIS)

    Gonzalez, P.R.; Alarcon, N.G.; Furetta, C.; Azorin, J.

    2003-01-01

    Ionizing radiation has different types of interaction with a crystalline solid. However, only few effects are interesting to optimize some thermoluminescent (Tl) properties of certain Tl materials. This paper presents results obtained by irradiating KMgF 3 : Lu + Ptfe Tl dosimeters with ultraviolet (UV) radiation previously exposed to gamma radiation. These results showed that those dosimeters not exposed previously to gamma radiation did not presented any Tl signal. Meanwhile, those previously submitted to gamma irradiation showed that their sensitivity was increased as the gamma dose increased. The glow curve of sensitized KMgF 3 : Lu + Ptfe exposed to UV radiation, presented the dosimetric pea at 212 C. This makes this material to be promissory for measuring UV radiation. (Author)

  2. Characterization of the melting process of PTFE using positron annihilation spectroscopy

    International Nuclear Information System (INIS)

    Honda, Y; Nishijima, S

    2015-01-01

    Poly(tetrafluoroethylene) (PTFE) is a semi-crystalline polymer and the lifetime of ortho-positronium(o-Ps) is known to be able to be separated into two components due to annihilation in the crystal region and in the amorphous region. The melting process of PTFE was investigated using positron annihilation spectroscopy and X-ray diffraction. The results indicated that volume expansion with an increase of temperature is dominantly due to the expansion of the amorphous region and a Ps bubble is formed at melting in both regions. The o-Ps relating to the crystal region definitely remains on the surface of crystal at the time of annihilation. The production of lower energy electrons at melting was deduced by the analysis of the Doppler broadened annihilation photopeak, and the increase in the number of such electrons was found to have great influence on the formation of the o-Ps and annihilation processes of positron and o-Ps. (paper)

  3. 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.

  4. SELECTIVE HYDROGENATION OF CINNAMALDEHYDE WITH Pt AND Pt-Fe CATALYSTS: EFFECTS OF THE SUPPORT

    Directory of Open Access Journals (Sweden)

    A.B. da Silva

    1998-06-01

    Full Text Available Low-temperature reduced TiO2-supported Pt and Pt-Fe catalysts are much more active and selective for the liquid–phase hydrogenation of cinnamaldehyde to unsaturated cinnamyl alcohol than the corresponding carbon-supported catalysts. High-temperature reduced catalysts, where the SMSI effect should be present, are almost inactive for this reaction. There is at present no definitive explanation for this effect but an electronic metal-support interaction is most probably involved.

  5. Treatment of Malignant Biliary Obstruction with a PTFE-Covered Self-Expandable Nitinol Stent

    International Nuclear Information System (INIS)

    Han, Young-Min; Kwak, Hyo-Sung; Jin, Gong-Yong; Lee, Seung-Ok; Chung, Gyung-Ho

    2007-01-01

    We wanted to determine the technical and clinical efficacy of using a PTFE-covered self-expandable nitinol stent for the palliative treatment of malignant biliary obstruction. Thirty-seven patients with common bile duct strictures caused by malignant disease were treated by placing a total of 37 nitinol PTFE stents. These stents were covered with PTFE with the exception of the last 5 mm at each end; the stent had an unconstrained diameter of 10 mm and a total length of 50 80 mm. The patient survival rate and stent patency rate were calculated by performing Kaplan-Meier survival analysis. The bilirubin, serum amylase and lipase levels before and after stent placement were measured and then compared using a Wilcoxon signed-rank test. The average follow-up duration was 27.9 weeks (range: 2 81 weeks). Placement was successful in all cases. Seventy-six percent of the patients (28/37) experienced adequate palliative drainage for the remainder of their lives. There were no immediate complications. Three patients demonstrated stent sludge occlusion that required PTBD (percutaneous transhepatic biliary drainage) irrigation. Two patients experienced delayed stent migration with stone formation at 7 and 27 weeks of follow-up, respectively. Stent insertion resulted in acute elevations of the amylase and lipase levels one day after stent insertion in 11 patients in spite of performing endoscopic sphincterotomy (4/6). The bilirubin levels were significantly reduced one week after stent insertion (p < 0.01). The 30-day mortality rate was 8% (3/37), and the survival rates were 49% and 27% at 20 and 50 weeks, respectively. The primary stent patency rates were 85%, and 78% at 20 and 50 weeks, respectively. The PTFE-covered self-expandable nitinol stent is safe to use with acceptable complication rates. This study is similar to the previous studies with regard to comparing the patency rates and survival rates

  6. Treatment of Malignant Biliary Obstruction with a PTFE-Covered Self-Expandable Nitinol Stent

    Energy Technology Data Exchange (ETDEWEB)

    Han, Young-Min; Kwak, Hyo-Sung; Jin, Gong-Yong; Lee, Seung-Ok; Chung, Gyung-Ho [Chonbuk National University Medical School and Hospital, Chonju (Korea, Republic of)

    2007-10-15

    We wanted to determine the technical and clinical efficacy of using a PTFE-covered self-expandable nitinol stent for the palliative treatment of malignant biliary obstruction. Thirty-seven patients with common bile duct strictures caused by malignant disease were treated by placing a total of 37 nitinol PTFE stents. These stents were covered with PTFE with the exception of the last 5 mm at each end; the stent had an unconstrained diameter of 10 mm and a total length of 50 80 mm. The patient survival rate and stent patency rate were calculated by performing Kaplan-Meier survival analysis. The bilirubin, serum amylase and lipase levels before and after stent placement were measured and then compared using a Wilcoxon signed-rank test. The average follow-up duration was 27.9 weeks (range: 2 81 weeks). Placement was successful in all cases. Seventy-six percent of the patients (28/37) experienced adequate palliative drainage for the remainder of their lives. There were no immediate complications. Three patients demonstrated stent sludge occlusion that required PTBD (percutaneous transhepatic biliary drainage) irrigation. Two patients experienced delayed stent migration with stone formation at 7 and 27 weeks of follow-up, respectively. Stent insertion resulted in acute elevations of the amylase and lipase levels one day after stent insertion in 11 patients in spite of performing endoscopic sphincterotomy (4/6). The bilirubin levels were significantly reduced one week after stent insertion (p < 0.01). The 30-day mortality rate was 8% (3/37), and the survival rates were 49% and 27% at 20 and 50 weeks, respectively. The primary stent patency rates were 85%, and 78% at 20 and 50 weeks, respectively. The PTFE-covered self-expandable nitinol stent is safe to use with acceptable complication rates. This study is similar to the previous studies with regard to comparing the patency rates and survival rates.

  7. SPIE 9639-49 Creation and Validation of Sintered PTFE BRDF Targets & Standards

    OpenAIRE

    Durell, Christopher; Scharpf, Dan; McKee, Greg; L’Heureux, Michelle; Georgiev, Georgi; Obein, Gael; Cooksey, Catherine

    2015-01-01

    Sintered polytetrafluoroethylene (PTFE) is an extremely stable, near-perfect Lambertian reflecting diffuser and calibration standard material that has been used by national labs, space, aerospace and commercial sectors for over two decades. New uncertainty targets of 2 % on-orbit absolute validation in the Earth Observing Systems community have challenged the industry to improve is characterization and knowledge of almost every aspect of radiometric performance (space and ground). Assuming “n...

  8. Ordered arrays of polymeric nanopores by using inverse nanostructured PTFE surfaces

    International Nuclear Information System (INIS)

    Martín, Jaime; Martín-González, Marisol; Del Campo, Adolfo; Reinosa, Julián J; Fernández, José Francisco

    2012-01-01

    We present a simple, efficient, and high-throughput methodology for the fabrication of ordered nanoporous polymeric surfaces with areas in the range of cm 2 . The procedure is based on a two-stage replication of a master nanostructured pattern. The process starts with the preparation of an ordered array of poly(tetrafluoroethylene) (PTFE) free-standing nanopillars by wetting self-ordered porous anodic aluminum oxide templates with molten PTFE. The nanopillars are 120 nm in diameter and approximately 350 nm long, while the array extends over cm 2 . The PTFE nanostructuring process induces surface hydrocarbonation of the nanopillars, as revealed by confocal Raman microscopy/spectroscopy, which enhances the wettability of the originally hydrophobic material and facilitates its subsequent use as an inverse pattern. Thus, the PTFE nanostructure is then used as a negative master for the fabrication of macroscopic hexagonal arrays of nanopores composed of biocompatible poly(vinylalcohol). In this particular case, the nanopores are 130–140 nm in diameter and the interpore distance is around 430 nm. Features of such characteristic dimensions are known to be easily recognized by living cells. Moreover, the inverse mold is not destroyed in the pore array demolding process and can be reused for further pore array fabrication. Therefore, the developed method allows the high-throughput production of cm 2 -scale biocompatible nanoporous surfaces that could be interesting as two-dimensional scaffolds for tissue repair or wound healing. Moreover, our approach can be extrapolated to the fabrication of almost any polymer and biopolymer ordered pore array. (paper)

  9. Change of wettability of PTFE surface by sputter etching and excimer laser. Sputter etching oyobi excimer laser ni yoru PTFE hyomen no shinsuika

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, S. (Nitto Denko Corp., Osaka (Japan)); Kubo, U. (Kinki University, Osaka (Japan))

    1994-06-20

    The wettability of PTFE (polytetrafluoroethylene) surfaces was improved by sputter etching and excimer laser irradiation. In sputter etching, the PTFE surface was treated by reactive sputter etching with H2O gas to give active groups on the surface. In laser irradiation, the surface was irradiated in pure water by high-energy KrF excimer laser. As the surface wettability was evaluated with a contact angle to water, the contact angle decreased remarkably in both treatments resulting in a good improvement effect. In sputter etching, various new chemical bonds such as F-C=O, F2C-FC-O, F2C-C-O and C-O were observed because of a decrease in F and incorporation of oxygen. Such chemical bonds could be eliminated by ultraviolet ray irradiation, and the treated surface condition approached the initial condition after irradiation of 200 hours. In laser irradiation, it was suggested that C-F bonds were broken, and OH groups were added to the surface by dissociation of H2O to H and OH. 7 refs., 8 figs., 1 tab.

  10. Annealing dependent evolution of columnar nanostructures in RF magnetron sputtered PTFE films for hydrophobic applications

    Science.gov (United States)

    Tripathi, S.; De, Rajnarayan; Maidul Haque, S.; Divakar Rao, K.; Misal, J. S.; Prathap, C.; Das, S. C.; Patidar, Manju M.; Ganesan, V.; Sahoo, N. K.

    2018-01-01

    Present communication focuses on a relatively less explored direction of producing rough polytetrafluoroethylene (PTFE) surfaces for possible hydrophobic applications. The experiments were carried out to make rough PTFE films without losing much of the transmission, which is an important factor while designing futuristic solar cell protection covers. After annealing temperature optimization, as grown RF magnetron sputtered PTFE films (prepared at 160 W RF power) were subjected to vacuum annealing at 200 °C for different time durations ranging from 1 to 4 h. The films show morphological evolution exhibiting formation and growth of columnar nanostructures that are responsible for roughening of the films due to annealing induced molecular migration and rearrangement. In agreement with this, qualitative analysis of corresponding x-ray reflectivity data shows modification in film thickness, which may again be attributed to the growth of columns at the expense of the atoms of remaining film molecules. However, the observations reveal that the film annealed at 200 °C for 2 h gives a combination of patterned columnar structures and reasonable transmission of >85% (in 500-1000 nm wavelength range), both of which are deteriorated when the films are annealed either at high temperature beyond 200 °C or for long durations >3 h. In addition, attenuated total reflection-Fourier transform infrared spectroscopy results reveal that the molecular bonds remain intact upon annealing at any temperature within the studied range indicating the stable nature of the films.

  11. 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.

  12. Combustion of PTFE: The Effects of Gravity and Pigmentation on Ultrafine Particle Generation

    Science.gov (United States)

    McKinnon, J. Thomas; Srivastava, Rajiv; Todd, Paul

    1997-01-01

    Ultrafine particles generated during polymer thermodegradation are a major health hazard, owing to their unique pathway of processing in the lung. This hazard in manned spacecraft is poorly understood, because the particulate products of polymer thermodegradation are generated under low gravity conditions. Particulate generated from the degradation of PolyTetraFluoroEthylene (PTFE), insulation coating for 20 AWG copper wire (representative of spacecraft application) under intense ohmic heating were studied in terrestrial gravity and microgravity. Microgravity tests were done in a 1.2-second drop tower at the Colorado School of Mines (CSM). Thermophoretic sampling was used for particulate collection. Transmission Electron Microscopy (TEM) and Scanning Transmission Electron Microscopy (STEM) were used to examine the smoke particulates. Image software was used to calculate particle size distribution. In addition to gravity, the color of PTFE insulation has an overwhelming effect on size, shape and morphology of the particulate. Nanometer-sized primary particles were found in all cases, and aggregation and size distribution was dependent on both color and gravity; higher aggregation occurred in low gravity. Particulates from white, black, red and yellow colored PTFE insulations were studied. Elemental analysis of the particulates shows the presence of inorganic pigments.

  13. Tl response of LiF:Mg, Cu, P + PTFE to Am-Be neutrons

    International Nuclear Information System (INIS)

    Gonzalez M, P.R.

    2000-01-01

    In different laboratories of the world it is followed the research about development of new Tl materials, whose main characteristics should be their equivalence with the tissue and their high sensibility to any type of radiation. The study consists in to measure the Tl peak intensity which TLD-100 presents at being irradiated with neutrons and that appears over 250 Centigrade, for compare it with the Tl intensity of the LiF: Mg, Cu, P + PTFE dosemeters. However, not all dosemeters of the same group show the interesting peak, by this only can be the total Tl intensity of dosemeters studied. In the ININ dosemeters development laboratory, we have developed a Tl material of lithium fluoride activated with magnesium, copper and phosphorus (LiF: Mg, Cu, P) that in polycrystalline powder form is almost 35 times more sensitive than the TLD-100 commercial dosemeter of Harshaw/Filtrol, USA. With the use of polytetrafluorethylene (PTFE) and with the above described Tl material, it has been possible to obtain dosemeters in pellet form of LiF: Mg, Cu, P + PTFE. (Author)

  14. Vessel Operator System

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Operator cards are required for any operator of a charter/party boat and or a commercial vessel (including carrier and processor vessels) issued a vessel permit from...

  15. Oxygen Compatibility of Brass-Filled PTFE Compared to Commonly Used Fluorinated Polymers for Oxygen Systems

    Science.gov (United States)

    Herald, Stephen D.; Frisby, Paul M.; Davis, Samuel Eddie

    2009-01-01

    Safe and reliable seal materials for high-pressure oxygen systems sometimes appear to be extinct species when sought out by oxygen systems designers. Materials that seal well are easy to find, but these materials are typically incompatible with oxygen, especially in cryogenic liquid form. This incompatibility can result in seals that leak, or much worse, seals that easily ignite and burn during use. Materials that are compatible with oxygen are easy to find, such as the long list of compatible metals, but these metallic materials are limiting as seal materials. A material that seals well and is oxygen compatible has been the big game in the designer's safari. Scientists at the Materials Combustion Research Facility (MCRF), part of NASA/Marshall Space Flight Center (MSFC), are constantly searching for better materials and processes to improve the safety of oxygen systems. One focus of this effort is improving the characteristics of polymers used in the presence of an oxygen enriched environment. Very few systems can be built which contain no polymeric materials; therefore, materials which have good impact resistance, low heat of combustion, high auto-ignition temperature and that maintain good mechanical properties are essential. The scientists and engineers at the Materials Combustion Research Facility, in cooperation with seal suppliers, are currently testing a new formulation of polytetrafluoroethylene (PTFE) with Brass filler. This Brass-filled PTFE is showing great promise as a seal and seat material for high pressure oxygen systems. Early research has demonstrated very encouraging results, which could rank this material as one of the best fluorinated polymers ever tested. This paper will compare the data obtained for Brass-filled PTFE with other fluorinated polymers, such as TFE-Teflon (PTFE) , Kel-F 81, Viton A, Viton A-500, Fluorel , and Algoflon . A similar metal filled fluorinated polymer, Salox-M , was tested in comparison to Brass-filled PTFE to

  16. The fabrication, nano/micro-structure, heat- and wear-resistance of the superhydrophobic PPS/PTFE composite coatings.

    Science.gov (United States)

    Wang, Huaiyuan; Zhao, Jingyan; Zhu, Youzhuang; Meng, Yang; Zhu, Yanji

    2013-07-15

    A simple engineering method was used to fabricate stability and wear-resistance of superhydrophobic PPS-based PPS/PTFE surfaces through nano/micro-structure design and modification of the lowest surface energy groups (-CF2-), which was inspired by the biomimic lotus leaves. The hydrophobic properties and wear-resistance of the coatings were measured by a contact angle meter and evaluated on a pin-on-disk friction and wear tester, respectively. Moreover, the surfaces of the PPS/PTFE composite coatings were investigated by means of scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), and thermogravimetry (TG) analysis. Results showed that the highest contact angle of the PPS/PTFE surface, with papillae-like randomly distributed double-scale structure, could reach up to 162°. When 1 wt.% PDMS was added, the highest contact angle could hold is 172°. The coatings also retained superhydrophobicity, even under high temperature environment. The investigation also indicated that the coatings were not only superhydrophobic but also oleophobic behavior at room temperature, such as the crude oil, glycerol, and oil-water mixture. The PPS/45%PTFE coatings had more stable friction coefficient and excellent wear-resistance (331,407 cycles) compared with those with less than 45% of PTFE. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. Thermal–Hydrodynamic Behaviour of Coated Pivoted Pad Thrust Bearings: Comparison between Babbitt, PTFE and DLC

    Directory of Open Access Journals (Sweden)

    Konstantinos Katsaros

    2018-05-01

    Full Text Available The hydrodynamic lubrication and thermal analysis of tilting pad thrust bearings has been a major subject for many studies in the field of tribology. There is only a limited number of studies regarding thrust bearings with coated surfaces. The purpose of this study is to build a parametric, iterative algorithm in order to perform a complete thermal and hydrodynamic lubrication analysis for pivoted pad thrust bearings with coatings. The analytical model is mainly based on the energy, continuity and Navier–Stokes equations, which are solved numerically with the Semi-Implicit Method for Pressure Linked Equations Consistent (SIMPLEC method. The analysis focuses on a single pivoted pad of the thrust bearing. The thermal properties of the coating material are taken into account and the resulting thermal and flow fields are solved. The basic hydrodynamic and tribological characteristics are calculated for an uncoated, a Babbitt coated, a PTFE coated and a diamond like carbon (DLC coated pivoted pad thrust bearing. The pressure and the film thickness distribution, as well as the load capacity and the frictional forces, are determined for several pad positions and velocities of the rotor. A mineral oil lubricant is used to estimate the shear thinning or thickening effects on the pad tribological performance. The results indicate that pads coated with PTFE and DLC show lower friction forces compared to the common steel and Babbitt applications. At the same time, the DLC coating seems to affect the bearing’s flow and thermal fields less than the PTFE, making it more suitable for thrust bearings applications.

  18. Ionizing radiation effects on ISS ePTFE jacketed cable assembly

    Science.gov (United States)

    Koontz, S. L.; Golden, J. L.; Lorenz, M. J.; Pedley, M. D.

    2003-09-01

    Polytetrafluoroethylene (PTFE), which is susceptible to embrittlement by ionizing radiation, is used as a primary material in the Mobile Transporter's (MT) Trailing Umbilical System (TUS) cable on the International Space Station (ISS). The TUS cable provides power and data service between the ISS truss and the MT. The TUS cable is normally stowed in an uptake reel and is fed out to follow the MT as it moves along rails on the ISS truss structure. For reliable electrical and mechanical performance, TUS cable polymeric materials must be capable of >3.5% elongation without cracking or breaking. The MT TUS cable operating temperature on ISS is expected to range between -100°C and +130°C. The on-orbit functional life requirement for the MT TUS cable is 10 years. Analysis and testing were performed to verify that the MT TUS cable would be able to meet full-life mechanical and electrical performance requirements, despite progressive embrittlement by the natural ionizing radiation environment. Energetic radiation belt electrons (trapped electrons) are the principal contributor to TUS cable radiation dose. TUS cable specimens were irradiated, in vacuum, with both energetic electrons and gamma rays. Electron beam energy was chosen to minimize charging effects on the non-conductive ePTFE (expanded PTFE) targets. Tensile testing was then performed, over the expected range of operating temperatures, as a function of radiation dose. When compared to the expected in-flight radiation dose/depth profile, atomic oxygen (AO) erosion of the radiation damaged TUS cable jacket surfaces is more rapid than the development of radiation induced embrittlement of the same surfaces. Additionally, the layered construction of the jacket prevents crack growth propagation, leaving the inner layer material compliant with the design elongation requirements. As a result, the TUS cable insulation design was verified to meet performance life requirements.

  19. Characterization of the early pulmonary inflammatory response associated with PTFE fume exposure

    Science.gov (United States)

    Johnston, C. J.; Finkelstein, J. N.; Gelein, R.; Baggs, R.; Oberdorster, G.; Clarkson, T. W. (Principal Investigator)

    1996-01-01

    Heating of polytetrafluoroethylene (PTFE) has been described to release fumes containing ultrafine particles (approximately 18 nm diam). These fumes can be highly toxic in the respiratory tract inducing extensive pulmonary edema with hemorrhagic inflammation. Fischer-344 rats were exposed to PTFE fumes generated by temperatures ranging from 450 to 460 degrees C for 15 min at an exposure concentration of 5 x 10(5) particles/cm3, equivalent to approximately 50 micrograms/m3. Responses were examined 4 hr post-treatment when these rats demonstrated 60-85% neutrophils (PMNs) in their lung lavage. Increases in abundance for messages encoding the antioxidants manganese superoxide dismutase and metallothionein (MT) increased 15- and 40-fold, respectively. For messages encoding the pro- and anti-inflammatory cytokines: inducible nitric oxide synthase, interleukin 1 alpha, 1 beta, and 6 (IL-1 alpha, IL-1 beta, and IL-6), macrophage inflammatory protein-2, and tumor necrosis factor-alpha (TNF alpha) increases of 5-, 5-, 10-, 40-, 40-, and 15-fold were present. Vascular endothelial growth factor, which may play a role in the integrity of the endothelial barrier, was decreased to 20% of controls. In situ sections were hybridized with 33P cRNA probes encoding IL-6, MT, surfactant protein C, and TNF alpha. Increased mRNA abundance for MT and IL-6 was expressed around all airways and interstitial regions with MT and IL-6 demonstrating similar spatial distribution. Large numbers of activated PMNs expressed IL-6, MT, and TNF alpha. Additionally, pulmonary macrophages and epithelial cells were actively involved. These observations support the notion that PTFE fumes containing ultrafine particles initiate a severe inflammatory response at low inhaled particle mass concentrations, which is suggestive of an oxidative injury. Furthermore, PMNs may actively regulate the inflammatory process through cytokine and antioxidant expression.

  20. Plasma polymer films rf sputtered from PTFE under various argon pressures

    Czech Academy of Sciences Publication Activity Database

    Stelmashuk, Vitaliy; Biederman, H.; Slavinská, D.; Zemek, Josef; Trchová, Miroslava

    2005-01-01

    Roč. 77, č. 2 (2005), s. 131-137 ISSN 0042-207X R&D Projects: GA MŠk(CZ) OC 527.10; GA MŠk(CZ) OC 527.90 Grant - others:EUREKAΣ2080(XE) OE57 Institutional research plan: CEZ:AV0Z10100521; CEZ:AV0Z20430508 Keywords : RF sputtering * PTFE * fluorcarbon plasma polymers * thin film * teflon * deposition Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.909, year: 2005

  1. Effects of 108 Days Tritium Exposure on UHMW-PE, PTFE, and Vespel(R)

    International Nuclear Information System (INIS)

    Clark, E.A.

    2003-01-01

    Samples of three polymers, Ultra-High Molecular Weight Polyethylene (UHMW-PE), polytetrafluoroethylene (PTFE), also known as Teflon(R), and Vespel(R) polyimide were exposed to 1 atmosphere of tritium gas at ambient temperature for 108 days. Sample mass and size measurements to calculate density, spectra-colorimetry, dynamic mechanical analysis (DMA), and Fourier-transform infrared spectroscopy (FT-IR) were employed to characterize the effects of this exposure on these samples. This technical report is the first report from this research program

  2. Thermal conductivity measurements of PTFE and Al2O3 ceramic at sub-Kelvin temperatures

    Science.gov (United States)

    Drobizhev, Alexey; Reiten, Jared; Singh, Vivek; Kolomensky, Yury G.

    2017-07-01

    The design of low temperature bolometric detectors for rare event searches necessitates careful selection and characterization of structural materials based on their thermal properties. We measure the thermal conductivities of polytetrafluoroethylene (PTFE) and Al2O3 ceramic (alumina) in the temperature ranges of 0.17-0.43 K and 0.1-1.3 K, respectively. For the former, we observe a quadratic temperature dependence across the entire measured range. For the latter, we see a cubic dependence on temperature above 0.3 K, with a linear contribution below that temperature. This paper presents our measurement techniques, results, and theoretical discussions.

  3. Ignition of PTFE-lined flexible hoses by rapid pressurization with oxygen

    Science.gov (United States)

    Janoff, Dwight; Bamford, Larry J.; Newton, Barry E.; Bryan, Coleman J.

    1989-01-01

    A high-volume pneumatic-impact system has been used to test PTFE-lined stainless steel braided hoses, in order to characterize the roles played in the mechanism of oxygen-induced ignition by impact pressure, pressurization rate, and upstream and downstream volumes of the hose. Ignitions are noted to have occurred at impact pressures well below the working pressure of the hoses, as well as at pressurization rates easily obtainable through manual operation of valves. The use of stainless steel hardlines downstream of the hose prevented ignitions at all pressures and pressurization rates; internal observations have shown evidence of shock ionization in the oxygen prior to ignition.

  4. Lamp system with conditioned water coolant and diffuse reflector of polytetrafluorethylene(PTFE)

    Science.gov (United States)

    Zapata, Luis E.; Hackel, Lloyd

    1999-01-01

    A lamp system with a very soft high-intensity output is provided over a large area by water cooling a long-arc lamp inside a diffuse reflector of polytetrafluorethylene (PTFE) and titanium dioxide (TiO.sub.2) white pigment. The water is kept clean and pure by a one micron particulate filter and an activated charcoal/ultraviolet irradiation system that circulates and de-ionizes and biologically sterilizes the coolant water at all times, even when the long-arc lamp is off.

  5. Thermoluminescent response of CaSO4: Dy + PTFE to beta particles

    International Nuclear Information System (INIS)

    Aguirre C, A.; Azorin N, J.

    2000-01-01

    In this work the results of studying the thermoluminescent properties of CaSO 4 : Dy + PTFE are presented when it is irradiated with beta particles. The conclusion was the obtention of the Tl response curve in function of dose is that to desexcite the dosemeters at temperature 300 C during 30 minutes and after that were irradiated at different times in groups and to do the reading of dosemeter, it can be observed that a greater irradiation time major is the Tl response and this depends of the material has been used. (Author)

  6. Accelerated electron beams for production of heat shrinkable polymeric products and PTFE wastes recovery

    Energy Technology Data Exchange (ETDEWEB)

    Marin, Gh; Marcuta, M [SC ICPE Electrostatica SA, Bucharest (Romania); Jipa, S [' Valahia' University, Targoviste (Romania)

    2001-07-01

    Radiation curing, i.e. curing under the action of ionizing radiation (predominantly electron beams) is one of the most important areas of radiation processing. There are many practical applications of electron beam processing. Our research activity was focused on two of them: radiation cross-linking of polymeric materials; recovery of PTFE wastes. For this purpose we have used: an industrial electron accelerator ILU-6 with 2.5 MeV electron energy and 40kW beam power; equipment for the transport of materials under the electron beam; and a technologic line with typical equipment for the expansion process.

  7. Accelerated electron beams for production of heat shrinkable polymeric products and PTFE wastes recovery

    International Nuclear Information System (INIS)

    Marin, Gh.; Marcuta, M.; Jipa, S.

    2001-01-01

    Radiation curing, i.e. curing under the action of ionizing radiation (predominantly electron beams) is one of the most important areas of radiation processing. There are many practical applications of electron beam processing. Our research activity was focused on two of them: radiation cross-linking of polymeric materials; recovery of PTFE wastes. For this purpose we have used: an industrial electron accelerator ILU-6 with 2.5 MeV electron energy and 40kW beam power; equipment for the transport of materials under the electron beam; and a technologic line with typical equipment for the expansion process

  8. A Novel Non-Planar Transverse Stretching Process for Micro-Porous PTFE Membranes and Resulting Characteristics

    KAUST Repository

    Chang, Y.-H.

    2018-02-26

    Polytetrafluoroethylene (PTFE) micro-porous membranes were prepared from PTFE fine powder through extruding, rolling, and uniaxial longitudinally stretching. In contrast to conventional planar transverse stretching, a novel 3D mold design of non-planar transverse stretching process was employed in this study to produce micro-porous structure. The morphology, membrane thickness, mean pore size, and porosity of the PTFE membrane were investigated. The results show that the non-planar transverse stretched membranes exhibit more uniform average pore diameter with thinner membrane thickness. Morphological changes induced by planar and non-planar transverse stretching for pore characteristics were investigated. The stretching conditions, stretching temperature and rate, affect the stretched membrane. Increasing temperature facilitated the uniformity of pore size and uniformity of membrane thickness. Moreover, increase in stretching rate resulted in finer pore size and thinner membrane.

  9. Multiple shell pressure vessel

    International Nuclear Information System (INIS)

    Wedellsborg, B.W.

    1988-01-01

    A method is described of fabricating a pressure vessel comprising the steps of: attaching a first inner pressure vessel having means defining inlet and outlet openings to a top flange, placing a second inner pressure vessel, having means defining inlet and outlet opening, concentric with and spaced about the first inner pressure vessel and attaching the second inner pressure vessel to the top flange, placing an outer pressure vessel, having inlet and outlet openings, concentric with and spaced apart about the second inner pressure vessel and attaching the outer pressure vessel to the top flange, attaching a generally cylindrical inner inlet conduit and a generally cylindrical inner outlet conduit respectively to the inlet and outlet openings in the first inner pressure vessel, attaching a generally cylindrical outer inlet conduit and a generally cylindrical outer outlet conduit respectively to the inlet and outlet opening in the second inner pressure vessel, heating the assembled pressure vessel to a temperature above the melting point of a material selected from the group, lead, tin, antimony, bismuth, potassium, sodium, boron and mixtures thereof, filling the space between the first inner pressure vessel and the second inner pressure vessel with material selected from the group, filling the space between the second inner pressure vessel and the outer pressure vessel with material selected from the group, and pressurizing the material filling the spaces between the pressure vessels to a predetermined pressure, the step comprising: pressurizing the spaces to a pressure whereby the wall of the first inner pressure vessel is maintained in compression during steady state operation of the pressure vessel

  10. The mechanism of PTFE and PE friction deposition: a combined scanning electron and scanning force microscopy study on highly oriented polymeric sliders

    NARCIS (Netherlands)

    Schönherr, Holger; Schaeben, H.; Vancso, Gyula J.

    1998-01-01

    The mechanism of friction deposition of polytetrafluoroethylene (PTFE) and polyethylene (PE) was studied by scanning electron (SEM) and scanning force microscopy (SFM) on the worn surfaces of PTFE and PE sliders that were used in friction deposition on glass substrates. These surfaces exhibited a

  11. Preparation and performance of Pt/PTFE/Foam SiC as a hydrophobic catalyst for LPCE

    Energy Technology Data Exchange (ETDEWEB)

    He, Jianchao; Wang, Heyi, E-mail: hywang@caep.cn; Xiao, Chengjian; Li, Jiamao; Chen, Ping; Hou, Jingwei

    2016-12-15

    Highlights: • A new type of foam material, Foam SiC with three-dimensional network structure, was chosen as the carrier of catalyst. • Foam SiC was hydrophobic treated by PTFE, and achieved a good hydrophobic property. • Pt/PTFE/Foam SiC was prepared by impregnation method with Pt-organic solution and gaseous phase reduction method. • The hydrophobic catalysts were packed with Dixon phosphor bronze gauze rings (about 3 mm × 3 mm) in LPCE system to test the catalytic performance. • The effect of different size of the catalyst on LPCE was been tested. - Abstract: Platinum catalysts supported on a composite of polytetrafluoroethylene (PTFE) and Foam SiC (Pt/PTFE/Foam SiC) have been proposed and prepared by an impregnation method. The as-prepared Pt/PTFE/Foam SiC was characterized by compression load testing, dynamic contact angle measurement, SEM, XRD, and TEM. The results show that the catalyst prepared by triple hydrophobic treatment had an initial contact angle of 134.2°, a good compression performance of 3.2 MPa, and platinum nanoparticles of 12.1 nm (average size). The catalytic activity of the catalyst was tested with different packing methods, reaction temperatures, and gas-liquid ratios. An excellent hydrogen isotope exchange performance was observed using a hydrophilic packing material-to-catalyst ratio of 25% and reaction temperature of 80 °C. Pt/PTFE/Foam SiC may be used as a hydrophobic catalyst for a water detritiation system (WDS) via a liquid-phase catalytic exchange process (LPCE).

  12. Preparation and performance of Pt/PTFE/Foam SiC as a hydrophobic catalyst for LPCE

    International Nuclear Information System (INIS)

    He, Jianchao; Wang, Heyi; Xiao, Chengjian; Li, Jiamao; Chen, Ping; Hou, Jingwei

    2016-01-01

    Highlights: • A new type of foam material, Foam SiC with three-dimensional network structure, was chosen as the carrier of catalyst. • Foam SiC was hydrophobic treated by PTFE, and achieved a good hydrophobic property. • Pt/PTFE/Foam SiC was prepared by impregnation method with Pt-organic solution and gaseous phase reduction method. • The hydrophobic catalysts were packed with Dixon phosphor bronze gauze rings (about 3 mm × 3 mm) in LPCE system to test the catalytic performance. • The effect of different size of the catalyst on LPCE was been tested. - Abstract: Platinum catalysts supported on a composite of polytetrafluoroethylene (PTFE) and Foam SiC (Pt/PTFE/Foam SiC) have been proposed and prepared by an impregnation method. The as-prepared Pt/PTFE/Foam SiC was characterized by compression load testing, dynamic contact angle measurement, SEM, XRD, and TEM. The results show that the catalyst prepared by triple hydrophobic treatment had an initial contact angle of 134.2°, a good compression performance of 3.2 MPa, and platinum nanoparticles of 12.1 nm (average size). The catalytic activity of the catalyst was tested with different packing methods, reaction temperatures, and gas-liquid ratios. An excellent hydrogen isotope exchange performance was observed using a hydrophilic packing material-to-catalyst ratio of 25% and reaction temperature of 80 °C. Pt/PTFE/Foam SiC may be used as a hydrophobic catalyst for a water detritiation system (WDS) via a liquid-phase catalytic exchange process (LPCE).

  13. Introduction of oxygen vacancies and fluorine into TiO2 nanoparticles by co-milling with PTFE

    International Nuclear Information System (INIS)

    Senna, Mamoru; Šepelák, Vladimir; Shi, Jianmin; Bauer, Benjamin; Feldhoff, Armin; Laporte, Vincent; Becker, Klaus-Dieter

    2012-01-01

    Solid-state processes of introducing oxygen vacancies and transference of fluorine to n-TiO 2 nanoparticles by co-milling with poly(tetrafluoroethylene) (PTFE) powder were examined by diffuse reflectance spectroscopy (DRS) of UV, visual, near- and mid-IR regions, thermal analyses (TG-DTA), energy-dispersive X-ray spectroscopy (EDXS), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). The broad absorption peak at around 8800 cm −1 (1140 nm) was attributed to the change in the electronic states, viz. electrons trapped at the oxygen vacancies (Vo) and d–d transitions of titanium ions. Incorporation of fluorine into n-TiO 2 was concentrated at the near surface region and amounted to ca. 40 at% of the total fluorine in PTFE, after co-milling for 3 h, as confirmed by the F1s XPS spectrum. The overall atomic ratio, F/Ti, determined by EDXS was 0.294. By combining these analytical results, a mechanism of the present solid state processes at the boundary between PTFE and n-TiO 2 was proposed. The entire process is triggered by the partial oxidative decomposition of PTFE. This is accompanied by the abstraction of oxygen atoms from the n-TiO 2 lattices. Loss of the oxygen atoms results in the formation of the diverse states of locally distorted coordination units of titania, i.e. TiO 6−n Vo n , located at the near surface region. This leads subsequent partial ligand exchange between F and O, to incorporate fluorine preferentially to the near surface region of n-TiO 2 particles, where local non-crystalline states predominate. - Graphical abstract: Scheme of the reaction processes: (a) pristine mixture, (b) oxygen abstraction from TiO 2 and (c) fluorine migration from PTFE to TiO 2 . Highlights: Transfer of fluorine from PTFE to n-TiO 2 in a dry solid state process was confirmed. ► 40% of F in PTFE was incorporated to the near surface region of n-TiO 2 nanoparticles. ► The transfer process is

  14. Changes in the tribological behavior of an epoxy resin by incorporating CuO nanoparticles and PTFE microparticles

    DEFF Research Database (Denmark)

    Larsen, Thomas Ricco Ølholm; Andersen, Tom Løgstrup; Thorning, Bent

    2008-01-01

    by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), which show a relatively good dispersion of both kinds of particles. Differential scanning calorimetry (DSC) and Vickers hardness measurements show no clear changes in glass transition temperature or hardness as a function...... of the composites using a smoother counterface. This gives rise to significantly less wear, which for composites without PTFE is attributed to formation of a protective transfer film. At a pv condition of 1.16 MPa, 1.0 m1s the following is found: composites without PTFE generally show an unsteady behavior with high...

  15. 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

  16. Immobilization of Ochrobactrum tritici As5 on PTFE thin films for arsenite biofiltration.

    Science.gov (United States)

    Branco, Rita; Sousa, Tânia; Piedade, Ana P; Morais, Paula V

    2016-03-01

    Ochrobactrum tritici SCII24T bacteria is an environmental strain with high capacity to resist to arsenic (As) toxicity, which makes it able to grow in the presence of As(III). The inactivation of the two functional arsenite efflux pumps, ArsB and ACR3_1, resulted in the mutant O. tritici As5 exhibiting a high accumulation of arsenite. This work describes a method for the immobilization of the mutant cells O. tritici As5, on a commercial polymeric net after sputtered modified by the deposition of poly(tetrafluoroethylene) (PTFE) thin films, and demonstrates the capacity of immobilized cells to accumulate arsenic from solutions. Six different set of deposition parameters for PTFE thin films were developed and tested in vitro regarding their ability to immobilize the bacterial cells. The surface that exhibited a mild zeta potential value, hydrophobic characteristics, the lowest surface free energy but with a high polar component and the appropriate ratio of chemical reactive groups allowed cells to proliferate and to grow as a biofilm. These immobilized cells maintained their ability to accumulate the surrounding arsenite, making it a great arsenic biofilter to be used in bioremediation processes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Investigation of PTFE transfer films by infrared emission spectroscopy and phase-locked ellipsometry

    Science.gov (United States)

    Lauer, James L.; Bunting, Bruce G.; Jones, William R., Jr.

    1988-01-01

    When a PTFE sheet was rubbed unidirectionally over a smooth surface of stainless steel an essentially monomolecular transfer film was formed. by ellipsometric and emission infrared spectroscopic techniques it was shown that the film was 10 to 15 A thick and birefringent. From the intensity differences of infrared bands obtained with a polarizer passing radiation polarized in mutually perpendicular planes, it was possible to deduce transfer film orientation with the direction of rubbing. After standing in air for several weeks the transfer films apparently increased in thickness by as much as threefold. At the same time both the index of refraction and the absorption index decreased. Examination of the surfaces by optical and electron microscopies showed that the films had become porous and flaky. These observations were consistent with previous tribological measurements. The coefficients of friction decreased with the formation of the transfer film but increased again as the film developed breaks. The applicability of the ellipsometric and polarized infrared emission techniques to the identification of monomolecular tribological transfer films of polymers such as PTFE has been demonstrated.

  18. Investigation of graft copolymerization modification of PTFE surface using microwave plasma

    International Nuclear Information System (INIS)

    Wen Yunjian; Guan Weishu; Fang Yan; Ying Yongxiang

    1995-03-01

    Investigation of graft copolymerization modification of PTFE surface with kind of one or another reactive monomers was performed by using non-equilibrium microwave plasma at 2.45 GHz under various operating conditions. Untreated clean samples and grafted samples were examined and analyzed with different surface analytical techniques such as X-Ray Photoelectron Spectroscopy (XPS), Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Scanning Electron Microscopy (SEM). The results showed that the occurrence of noticeable de-fluorination and cross linking on grafted surface, and different polar groups and content of oxygen-containing were introduced into the grafted surface of PTFE. Fibriform hetero-structure layer was also formed. These results confirmed the success of graft and indicated that the hydrophilicity of the grafted surface is excellent and a significant improvement in adhesion characteristics has been achieved. The experiments revealed that the changes in surface properties are correlated closely to the changes in chemical structure, composition and morphology. (8 figs., 1 refs.)

  19. Thermoluminescent signal fading of encapsulated lif: Mg,Ti detectors in PTFE-Teflon registered trademark

    International Nuclear Information System (INIS)

    Sasho Nikolovski, Sasho; Nikolovska, Lidija; Velevska, Marija; Velev, Velko

    2010-01-01

    Fading is a process when the latent information of a detector is unintentionally lost mainly due to the thermal influence. Thermoluminescent (TL) detectors have different sensitivities as far as the fading effect. Encapsulated TL detectors mounted within shielded filter holders are used during the personal monitoring of occupationally exposed persons in R. Macedonia. PTFE-Teflon registered trademark polymer is an example of encapsulation material that has a temperature resistance and it allows the luminescence signal to pass through. Since the encapsulated TL detectors cannot be submitted to annealing treatment in an oven, another fading reduction method is needed. The TL evaluation method suggested in this work is based on a specific glow-curve region. Irradiations were conducted using 90Sr/90Y source. Post-irradiation fade investigations were conducted for evaluation periods that varied up to 4 months. Two areas of the TL glow-curve were selected with the WimRems software. They correspond to the high and the low fading emission peaks (the lower temperature peaks display a greater degree of thermal fading than the higher temperature peaks). Post-irradiation fade is a contributing factor that affects the response of a thermoluminescent (TL) phosphor as a function of time. PTFE - Polytetrafluoroethylene most well known by the DuPont brand name Teflon registered trademark. (Author)

  20. 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.

  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. Probabilistic retinal vessel segmentation

    Science.gov (United States)

    Wu, Chang-Hua; Agam, Gady

    2007-03-01

    Optic fundus assessment is widely used for diagnosing vascular and non-vascular pathology. Inspection of the retinal vasculature may reveal hypertension, diabetes, arteriosclerosis, cardiovascular disease and stroke. Due to various imaging conditions retinal images may be degraded. Consequently, the enhancement of such images and vessels in them is an important task with direct clinical applications. We propose a novel technique for vessel enhancement in retinal images that is capable of enhancing vessel junctions in addition to linear vessel segments. This is an extension of vessel filters we have previously developed for vessel enhancement in thoracic CT scans. The proposed approach is based on probabilistic models which can discern vessels and junctions. Evaluation shows the proposed filter is better than several known techniques and is comparable to the state of the art when evaluated on a standard dataset. A ridge-based vessel tracking process is applied on the enhanced image to demonstrate the effectiveness of the enhancement filter.

  3. Improvement to reactor vessel

    International Nuclear Information System (INIS)

    1974-01-01

    The vessel described includes a prestressed concrete vessel containing a chamber and a removable cover closing this chamber. The cover is in concrete and is kept in its closed position by main and auxiliary retainers, comprising fittings integral with the concrete of the vessel. The auxiliary retainers pass through the concrete of the cover. This improvement may be applied to BWR, PWR and LMFBR type reactor vessel [fr

  4. Pendulum support of the W7-X plasma vessel: Design, tests, manufacturing, assembly, critical aspects, status

    Energy Technology Data Exchange (ETDEWEB)

    Missal, B., E-mail: bernd.missal@ipp.mpg.de [Max-Planck-Institut für Plasmaphysik, EURATOM Association, Teilinstitut Greifswald, Wendelsteinstraße 1, D-17491 Greifswald (Germany); Leher, F.; Schiller, T. [MAN Diesel and Turbo SE, Werftstraße 17, 94469 Deggendorf (Germany); Friedrich, P. [Universität Rostock, FB Maschinenbau und Schiffstechnik, Albert-Einsteins-Straße 2, 18051 Rostock (Germany); Capriccioli, A. [ENEA Frascati, Fusion Technology Unit, Frascati (Italy)

    2014-10-15

    Highlights: • Plasma vessel support has to allow vertical adjustment and horizontal passive movement. • Planar sliding tables with PTFE do not fulfill all requirements. • Pendulums can fulfill all requirements. • Geometry and material of spherical bearings had to be optimized in calculations and tests. • Optimized pendulums were manufactured and assembled. - Abstract: The superconducting helical advanced stellarator Wendelstein 7-X (W7-X) is under construction at the Max-Planck-Institut für Plasmaphysik (IPP) in Greifswald, Germany. The three dimensional shape of plasma will be generated by 50 non-planar magnetic coils. The plasma vessel geometry follows exactly this three dimensional shape of plasma. To ensure the superconductivity of coils a cryo vacuum has to be generated. Therefore the coils and their support structure are enclosed within the outer vessel. Plasma vessel, coil structures and outer vessel have to be supported separately. This paper will describe the vertical supports of plasma vessel which have to fulfill two special requirements, vertical adjustability and horizontal mobility. These two tasks will be carried out by plasma vessel supports (PVS) with hydraulic cylinders, special sliding tables during assembly and pendulum supports during operating phase. The paper will give an overview of design, calculation, tests, fabrication, assembly, critical aspects and status of PVS.

  5. ALICE HMPID Radiator Vessel

    CERN Document Server

    2003-01-01

    View of the radiator vessels of the ALICE/HMPID mounted on the support frame. Each HMPID module is equipped with 3 indipendent radiator vessels made out of neoceram and fused silica (quartz) windows glued together. The spacers inside the vessel are needed to stand the hydrostatic pressure. http://alice-hmpid.web.cern.ch/alice-hmpid

  6. Thermoluminescent characteristics of CaSO{sub 4}:Dy+PTFE irradiated with high energy electron beams; Caracteristicas termoluminiscentes del CaSO{sub 4}:Dy+PTFE irradiado con haces de electrones de alta energia

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, R.; Rivera, T.; Calderon, J. A.; Jimenez, Y. [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria 694, Col. Irrigacion, 11500 Mexico D. F. (Mexico); Rodriguez, J. [Hospital General de Mexico, Dr. Balmis 148, Col. Doctores, 06726 Mexico D. F. (Mexico); Oviedo, O. [Centro Medico ABC, Sur 136 No. 116, Col. Las Americas, 01120 Mexico D. F. (Mexico); Azorin, J., E-mail: chagua@hotmail.com [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Av. San Rafael Atlixco 186, 09340 Mexico D. F. (Mexico)

    2011-10-15

    In the present work thermoluminescent response of dysprosium doped calcium sulfate embedded in polytetrafluorethylene (CaSO{sub 4}:Dy+PTFE) under high electron beam irradiations from linear accelerator for clinical applications was investigated. The irradiations were carried out using high electron beams (6 to 18 MeV) from a linear accelerator Varian, C linac 2300C/D, for clinical practice purpose. The electron irradiations were obtained by using the water solid in order to guarantee electronic equilibrium conditions. Field shaping for electron beams was obtained with electron cones. Glow curve and other thermoluminescent characteristics of CaSO{sub 4}:Dy+PTFE were conducted under high electron beams irradiations. The thermoluminescent response of the pellets showed and intensity peak centered at around 235 C. Thermoluminescent response of CaSO{sub 4}:Dy+PTFE as a function of high electron absorbed dose showed a linearity in a wide range. To obtain reproducibility characteristic, a set of pellets were exposed repeatedly for the same electron absorbed dose. The results obtained in this study can suggest the applicability of CaSO{sub 4}:Dy+PTFE pellets for high electron beam dosimetry, provided fading is correctly accounted for. (Author)

  7. Metallurgy of steels for PWR pressure vessels

    International Nuclear Information System (INIS)

    Kepka, M.; Mocek, J.; Barackova, L.

    1980-01-01

    A survey and the chemical compositions are presented of reactor pressure vessel steels. The metallurgy is described of steel making for pressure vessels in Japan and the USSR. Both acidic and alkaline open-hearth steel is used for the manufacture of ingots. The leading world manufacturers of forging ingots for pressure vessels, however, exclusively use electric steel. Vacuum casting techniques are exclusively used. Experience is shown gained with the introduction of the manufacture of forging ingots for pressure vessels at SKODA, Plzen. The metallurgical procedure was tested utilizing alkaline open hearths, electric arc furnaces and facilities for vacuum casting of steel. Pure charge raw materials should be used for securing high steel purity. Prior to forging pressure vessel rings, not only should sufficiently big bottoms and heads be removed but also the ingot middle part should be scrapped showing higher contents of impurities and nonhomogeneous structure. (B.S.)

  8. Metallurgy of steels for PWR pressure vessels

    Energy Technology Data Exchange (ETDEWEB)

    Kepka, M; Mocek, J; Barackova, L [Skoda, Plzen (Czechoslovakia)

    1980-09-01

    A survey and the chemical compositions are presented of reactor pressure vessel steels. The metallurgy is described of steel making for pressure vessels in Japan and the USSR. Both acidic and alkaline open-hearth steel is used for the manufacture of ingots. The leading world manufacturers of forging ingots for pressure vessels, however, exclusively use electric steel. Vacuum casting techniques are exclusively used. Experience is shown gained with the introduction of the manufacture of forging ingots for pressure vessels at SKODA, Plzen. The metallurgical procedure was tested utilizing alkaline open hearths, electric arc furnaces and facilities for vacuum casting of steel. Pure charge raw materials should be used for securing high steel purity. Prior to forging pressure vessel rings, not only should sufficiently big bottoms and heads be removed but also the ingot middle part should be scrapped showing higher contents of impurities and nonhomogeneous structure.

  9. 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.

  10. 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.

  11. [Research on ultrasonic permeability of low intensity pulsed ultrasound through PTFE membrane and Bio-Gide collagen membrane].

    Science.gov (United States)

    Chai, Zhaowu; Zhao, Chunliang; Song, Jinlin; Deng, Feng; Yang, Ji; Gao, Xiang; Liu, Minyi

    2013-12-01

    The aim of the present study was to detect the transmission rate of ultrasonic low intensity pulsed ultrasound (LIPUS) through polytetrafluoroethylene (PTFE) membrane (Thickness: 0.01 mm) and Bio-Gide collagen membrane, and to provide the basis for the barrier membrane selection on the study of LIPUS combined with guided tissue regeneration (GTR). The ultrasonic (LIPUS, frequency 1.5 MHz, pulse width 200 micros, repetition rate 1.0 kHz) transmission coefficient of the two kinds of barrier membrane were detected respectively through setting ten groups from 10 to 100mW/cm2 every other 10 mW/cm2. We found in the study that the ultrasonic transmission coefficient through 0.01 mm PTFE membrane was 78.1% to 92.%, and the ultrasonic transmission coefficient through Bio-Gide collagen membrane was 43.9% to 55.8%. The ultrasonic transmission coefficient through PTFE membrane was obviously higher than that through Bio-Gide collagen membrane. The transmission coefficient of the same barrier membrane of the ultrasonic ion was statistically different under different powers (P PTFE membrane and Bio-Gide collagen membrane were relatively high. We should select barrier membranes based on different experimental needs, and exercise ultrasonic transmission coefficient experiments to ensure effective power.

  12. 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

  13. Highly oriented thin films of a substituted oligo(para-phenylenevinylene) on friction-transferred PTFE substrates

    NARCIS (Netherlands)

    Gill, R.E; Hadziioannou, G; Lang, P.; Garnier, F.; Wittmann, J.C.

    Communication: Highly oriented thin films of oligo(p-phenylenevinylene)s, oligoPPVs, provide information about the structure of polyPPV and structure-property relationships. It is shown that deposition of a substituted oligoPPV onto highly preoriented PTFE substrates leads to highly oriented thin

  14. How to increase the hydrophobicity of PTFE surfaces using an r.f. atmospheric-pressure plasma torch

    NARCIS (Netherlands)

    Carbone, E.A.D.; Boucher, N.; Sferrazza, M.; Reniers, F.

    2010-01-01

    An experimental investigation of the surface modification of polytetrafluoroethylene (PTFE) by an Ar and Ar/O2 plasma created with an atmospheric-pressure radio frequency (r.f.) torch is presented here. The surfaces were analyzed by atomic force microscopy (AFM), XPS and water contact angle (WCA) to

  15. Improved extraction of ePTFE and medical adhesive modified defibrillation leads from the coronary sinus and great cardiac vein.

    Science.gov (United States)

    Wilkoff, Bruce L; Belott, Peter H; Love, Charles J; Scheiner, Avram; Westlund, Randy; Rippy, Marian; Krishnan, Mohan; Norlander, Barry E; Steinhaus, Bruce; Emmanuel, Janson; Zeller, Peter J

    2005-03-01

    Permanent leads with shocking coils for defibrillation therapy are sometimes implanted in the coronary sinus (CS) and great cardiac vein (GCV). These shocking coils, as documented by pathologic examination of animal investigations, often become tightly encapsulated by fibrosis and can be very difficult to remove. One of three configurations of the Guidant model 7109 Perimeter coronary sinus shocking lead was implanted into the distal portion of the GCV of 24 sheep for up to 14 months. Group 1 had unmodified coils (control), group 2 had coils backfilled with medical adhesive (MA), and Group 3 had coils coated with expanded polytetrafluoroethylene (ePTFE). Eighteen leads, three from each group at 6 and 14 months were transvenously extracted from the left jugular vein. The remaining six animals were not subject to extraction. All animals were euthanized for pathological and microscopic examination. All six of the control, three of the MA, and one of the ePTFE leads required the use of an electrosurgical dissection sheath (EDS) for extraction. Five control, two MA, and none of the ePTFE leads had significant fibrotic attachments to the shocking coils. Significant trauma was observed at necropsy for those leads requiring the use of the EDS for extraction. Tissue ingrowth is a major impediment to the removal of defibrillation leads implanted in the CS and GCV of sheep. Reduction of tissue ingrowth by coating the shocking coils with ePTFE or by backfilling with MA facilitates transvenous lead removal with reduced tissue trauma.

  16. Investigation of counterface surface topography effects on the wear and transfer behaviour of a POM-20% PTFE composite

    NARCIS (Netherlands)

    Franklin, S.E.; de Kraker, A.

    2003-01-01

    In order to gain greater insight into the relation between the wear rate, counterface surface topography and the characteristics of the transfer layer formed, a series of wear experiments have been performed with a commercial POM-20% PTFE composite sliding against hardened tool steel counterfaces in

  17. Linker-free covalent immobilization of heparin, SDF-1α, and CD47 on PTFE surface for antithrombogenicity, endothelialization and anti-inflammation.

    Science.gov (United States)

    Gao, Ang; Hang, Ruiqiang; Li, Wan; Zhang, Wei; Li, Penghui; Wang, Guomin; Bai, Long; Yu, Xue-Feng; Wang, Huaiyu; Tong, Liping; Chu, Paul K

    2017-09-01

    Small-diameter vascular grafts made of biomedical polytetrafluoroethylene (PTFE) suffer from the poor long-term patency rate originating from thrombosis and intimal hyperplasia, which can be ascribed to the insufficient endothelialization and chronic inflammation of the materials. Hence, bio-functionalization of PTFE grafts is highly desirable to circumvent these disadvantages. In this study, a versatile "implantation-incubation" approach in which the biomedical PTFE is initially modified by plasma immersion ion implantation (PIII) is described. After the N 2 PIII treatment, the surface of biomedical PTFE is roughened with nanostructures and more importantly, the abundant free radicals generated underneath the surface continuously migrate to the surface and react with environmental molecules. Taking advantage of this mechanism, various biomolecules with different functions can be steadily immobilized on the surface of PTFE by simple solution immersion. As examples, three typical biomolecules, heparin, SDF-1α, and CD47, are covalently grafted onto the PTFE. In addition to retaining the bioactivity, the surface-functionalized PTFE exhibits reduced thrombogenicity, facilitates the recruitment of endothelial progenitor cells, and even alleviates the inflammatory immune responses of monocytes-macrophages and is thus promising to the development of small-diameter prosthetic vascular grafts with good long-term patency. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Dacron® vs. PTFE as bypass materials in peripheral vascular surgery – systematic review and meta-analysis

    Science.gov (United States)

    Roll, Stephanie; Müller-Nordhorn, Jacqueline; Keil, Thomas; Scholz, Hans; Eidt, Daniela; Greiner, Wolfgang; Willich, Stefan N

    2008-01-01

    Background In peripheral vascular bypass surgery different synthetic materials are available for bypass grafting. It is unclear which of the two commonly used materials, polytetrafluoroethylene (PTFE) or polyester (Dacron®) grafts, is to be preferred. Thus, the aim of this meta-analysis and systematic review was to compare the effectiveness of these two prosthetic bypass materials (Dacron® and PTFE). Methods We performed a systematic literature search in MEDLINE, Cochrane-Library – CENTRAL, EMBASE and other databases for relevant publications in English and German published between 1999 and 2008. Only randomized controlled trials were considered for inclusion. We assessed the methodological quality by means of standardized checklists. Primary patency was used as the main endpoint. Random-effect meta-analysis as well as pooling data in life table format was performed to combine study results. Results Nine randomized controlled trials (RCT) were included. Two trials showed statistically significant differences in primary patency, one favouring Dacron® and one favouring PTFE grafts, while 7 trials did not show statistically significant differences between the two materials. Meta-analysis on the comparison of PTFE vs. Dacron® grafts yielded no differences with regard to primary patency rates (hazard ratio 1.04 (95% confidence interval [0.85;1.28]), no significant heterogeneity (p = 0.32, I2 = 14%)). Similarly, there were no significant differences with regard to secondary patency rates. Conclusion Systematic evaluation and meta-analysis of randomized controlled trials comparing Dacron® and PTFE as bypass materials for peripheral vascular surgery showed no evidence of an advantage of one synthetic material over the other. PMID:19099583

  19. Dacron® vs. PTFE as bypass materials in peripheral vascular surgery – systematic review and meta-analysis

    Directory of Open Access Journals (Sweden)

    Eidt Daniela

    2008-12-01

    Full Text Available Abstract Background In peripheral vascular bypass surgery different synthetic materials are available for bypass grafting. It is unclear which of the two commonly used materials, polytetrafluoroethylene (PTFE or polyester (Dacron® grafts, is to be preferred. Thus, the aim of this meta-analysis and systematic review was to compare the effectiveness of these two prosthetic bypass materials (Dacron® and PTFE. Methods We performed a systematic literature search in MEDLINE, Cochrane-Library – CENTRAL, EMBASE and other databases for relevant publications in English and German published between 1999 and 2008. Only randomized controlled trials were considered for inclusion. We assessed the methodological quality by means of standardized checklists. Primary patency was used as the main endpoint. Random-effect meta-analysis as well as pooling data in life table format was performed to combine study results. Results Nine randomized controlled trials (RCT were included. Two trials showed statistically significant differences in primary patency, one favouring Dacron® and one favouring PTFE grafts, while 7 trials did not show statistically significant differences between the two materials. Meta-analysis on the comparison of PTFE vs. Dacron® grafts yielded no differences with regard to primary patency rates (hazard ratio 1.04 (95% confidence interval [0.85;1.28], no significant heterogeneity (p = 0.32, I2 = 14%. Similarly, there were no significant differences with regard to secondary patency rates. Conclusion Systematic evaluation and meta-analysis of randomized controlled trials comparing Dacron® and PTFE as bypass materials for peripheral vascular surgery showed no evidence of an advantage of one synthetic material over the other.

  20. Absorbed dose measurements in mammography using Monte Carlo method and ZrO2+PTFE dosemeters

    International Nuclear Information System (INIS)

    Duran M, H. A.; Hernandez O, M.; Salas L, M. A.; Hernandez D, V. M.; Vega C, H. R.; Pinedo S, A.; Ventura M, J.; Chacon, F.; Rivera M, T.

    2009-10-01

    Mammography test is a central tool for breast cancer diagnostic. In addition, programs are conducted periodically to detect the asymptomatic women in certain age groups; these programs have shown a reduction on breast cancer mortality. Early detection of breast cancer is achieved through a mammography, which contrasts the glandular and adipose tissue with a probable calcification. The parameters used for mammography are based on the thickness and density of the breast, their values depend on the voltage, current, focal spot and anode-filter combination. To achieve an image clear and a minimum dose must be chosen appropriate irradiation conditions. Risk associated with mammography should not be ignored. This study was performed in the General Hospital No. 1 IMSS in Zacatecas. Was used a glucose phantom and measured air Kerma at the entrance of the breast that was calculated using Monte Carlo methods and ZrO 2 +PTFE thermoluminescent dosemeters, this calculation was completed with calculating the absorbed dose. (author)

  1. Burning and radiance properties of red phosphorus in Magnesium/PTFE/Viton (MTV)-based compositions

    Science.gov (United States)

    Li, Jie; Chen, Xian; Wang, Yanli; Shi, Yuanliang; Shang, Junteng

    2017-09-01

    Red phosphorus (RP) a highly efficient smoke-producing agent. In this study different contents of RP are added into the Magnesium/PTFE/Viton (MTV)-based composition, with the aim of investigating the influence of RP on the burning and radiance properties of MTV-based composition by using a high-temperature differential thermobalance method, a Fourier Transform Infrared (FTIR) remote-sensing spectrometer, a FTIR Spectrometer and a far-infrared thermal imager. The results show that RP improves the initial reaction temperature and reduces the mass burning rate by 0.1-0.17 g·s-1 (34-59%). The addition of RP has no obvious effect on the burning temperature and far-infrared radiation brightness, but the radiating area raises substantially (by 141%), and thus improves the radiation intensity (by 155%).

  2. PTFE-nanocomposites structure and wear-resistance changing in various methods of structural modification

    Science.gov (United States)

    Mashkov, Yu K.; Ruban, A. S.; Rogachev, E. A.; Chemisenko, O. V.

    2018-01-01

    Conditions of polymer materials usage containing nanoelements as modifiers significantly affect the requirements for their physic-mechanical and tribological properties. However, the mechanisms of nanoparticles effect to the polymers tribotechnical properties have not been studied enough. The article aim is to analyze the results of studying polytetrafluoroethylene modified with cryptocrystalline graphite and silicon dioxide and to determine the effectiveness of the modification methods used and methods for further improving filled PTFE mechanical and tribotechnical properties. The effect of modifiers to PCM supramolecular structure was analyzed with SEM methods. The results of modifying the PCM samples surface by depositing a copper film with ion-vacuum deposition methods and changing the structural-phase composition and tribological characteristics are considered. The findings make possible to characterize the physicochemical processes under frictional interaction in metal polymer tribosystems.

  3. Temperature profiles of an ablation controlled arc in PTFE: II. Simulation of side-on radiances

    International Nuclear Information System (INIS)

    Schneidenbach, H; Uhrlandt, D; Franke, St; Seeger, M

    2007-01-01

    The temperature determination by spectroscopic measurements in high-current high-pressure arcs in a polytetrafluoroethylene (PTFE) nozzle under the assumption of an optically thin plasma has been investigated. Assuming local thermodynamic equilibrium the radial temperature distributions as well as the plasma pressures have been determined by fitting a model to measured spectral radiances considering line and continuum absorption. It is shown that absorption has to be included in the error estimate of the experimental results. The different effects, which cause deviations from the optically thin case, have been analysed numerically and by using a simplified analytical model. The theoretically estimated pressures sensitively depend on the Stark broadening. In the studied plasmas the calculated large electron densities indicate a marked reduction of the Stark widths by nonideality effects. The applicability of the experimental method has been proved for suitably chosen lines

  4. Optimization of the obtaining method of CaSO4: Dy + Ptfe dosimeters

    International Nuclear Information System (INIS)

    Galicia A, J.; Rioja Ch, J.; Torijano C, E.; Azorin N, J.

    2012-10-01

    This work contain the obtained results of studying the response when irradiating to different dose of X-rays, dosimeters of CaSO 4 : Dy + Ptfe using different lapses of time in their preparation (a lot of selected dosimeters of an elaboration process of 3 days and another of an elaboration process of 2 hours). For the elaboration of the powdered material, the evaporation method was used; the irradiation were carried out in a lineal accelerator Elekta Synergy property of the National Medical Center, 20 de November. The similarities and differences are shown among the two dosimeters lots together with an analysis of the shine curves and of calibration selecting those that presented a better behaviour and a more rea liable response. (Author)

  5. Dosimetry of beta particles using Li:Mg, Cu, P + Ptfe

    International Nuclear Information System (INIS)

    Olvera, L.; Azorin, J.; Rivera, T.

    2003-01-01

    This paper presents the experimental results of determining the thermoluminescence (Tl) response of LiF: Mg, Cu, P + Ptfe pellets excited with 90 Sr/ 90 Y beta radiation. The glow curve exhibited three peaks which appear at 121 C, 178 C and 217 C . Its relative sensitivity is 49 with respect to that of the TLD-100 dosemeter taken as a reference. The minimal dose that could be measured was 750 mGy. The Tl response as a function of dose was linear in the range of 0.7 mGy to 22.5 mGy. The study of the repeatability of the information contained in the pellets showed a standard deviation of 2 %. (Author)

  6. Bronchobiliary Fistula Treated by Self-expanding ePTFE-Covered Nitinol Stent-Graft

    International Nuclear Information System (INIS)

    Gandini, Roberto; Konda, Daniel; Tisone, Giuseppe; Pipitone, Vincenzo; Anselmo, Alessandro; Simonetti, Giovanni

    2005-01-01

    A 71-year-old man, who had undergone right hepatectomy extended to the caudate lobe with terminolateral Roux-en-Y left hepatojejunostomy for a Klatskin tumor, developed bilioptysis 3 weeks postoperatively due to bronchobiliary fistula. Percutaneous transhepatic cholangiography revealed a non-dilated biliary system with contrast medium extravasation to the right subphrenic space through a resected anomalous right posterior segmental duct. After initial unsuccessful internal-external biliary drainage, the fistula was sealed with a VIATORR covered self-expanding nitinol stent-graft placed with its distal uncovered region in the hepatojejunal anastomosis and the proximal ePTFE-lined region in the left hepatic duct. A 10-month follow-up revealed no recurrence of bilioptysis and confirmed the complete exclusion of the bronchobiliary fistula

  7. Investigation of optical and microstructural properties of RF magnetron sputtered PTFE films for hydrophobic applications

    International Nuclear Information System (INIS)

    Tripathi, S.; Haque, S. Maidul; Rao, K. Divakar; De, Rajnarayan; Shripathi, T.; Deshpande, U.; Ganesan, V.; Sahoo, N.K.

    2016-01-01

    Highlights: • Polytetrafluoroethylene films were made by RF sputtering by varying deposition time. • With increasing deposition time, thickness shows unusual trend due to backsputtering. • Major contribution of CF 2 and CF 3 bonds in the samples is seen by ATR-FTIR. • Deposition time influences film thickness but all samples remain hydrophobic. • XPS spectra show strong CF x bonds at the surface. - Abstract: The deposition time dependence of optical, structural and morphological properties of thin as well as ultrathin Polytetrafluoroethylene (PTFE) sputtered films have been explored in the present communication. The films were prepared by RF magnetron sputtering under high vacuum condition, as a function of deposition time. The ellipsometry as well as X-ray reflectivity data show a drastic reduction in film thickness as the deposition time increases from 5 s to 10 s, possibly as a consequence of back sputtering. With subsequent deposition, back sputtering component decreases and hence, thickness increases with increase in deposition time. Atomic force microscopy (AFM) images show a slight change in growth morphology although roughness is independent of deposition time. Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) measurements showed the presence of C−C and CF x (x = 1–3) bonds in all the PTFE films. Supporting this, corresponding X-ray photoelectron spectroscopy (XPS) curves fitted for C-1s and F-1s peaks revealed a major contribution from CF 2 bonds along with significant contribution from CF 3 bonds leading to an F/C ratio of ∼1.5 giving hydrophobic nature of all the films.

  8. Pressure vessel design manual

    CERN Document Server

    Moss, Dennis R

    2013-01-01

    Pressure vessels are closed containers designed to hold gases or liquids at a pressure substantially different from the ambient pressure. They have a variety of applications in industry, including in oil refineries, nuclear reactors, vehicle airbrake reservoirs, and more. The pressure differential with such vessels is dangerous, and due to the risk of accident and fatality around their use, the design, manufacture, operation and inspection of pressure vessels is regulated by engineering authorities and guided by legal codes and standards. Pressure Vessel Design Manual is a solutions-focused guide to the many problems and technical challenges involved in the design of pressure vessels to match stringent standards and codes. It brings together otherwise scattered information and explanations into one easy-to-use resource to minimize research and take readers from problem to solution in the most direct manner possible. * Covers almost all problems that a working pressure vessel designer can expect to face, with ...

  9. Tumor Blood Vessel Dynamics

    Science.gov (United States)

    Munn, Lance

    2009-11-01

    ``Normalization'' of tumor blood vessels has shown promise to improve the efficacy of chemotherapeutics. In theory, anti-angiogenic drugs targeting endothelial VEGF signaling can improve vessel network structure and function, enhancing the transport of subsequent cytotoxic drugs to cancer cells. In practice, the effects are unpredictable, with varying levels of success. The predominant effects of anti-VEGF therapies are decreased vessel leakiness (hydraulic conductivity), decreased vessel diameters and pruning of the immature vessel network. It is thought that each of these can influence perfusion of the vessel network, inducing flow in regions that were previously sluggish or stagnant. Unfortunately, when anti-VEGF therapies affect vessel structure and function, the changes are dynamic and overlapping in time, and it has been difficult to identify a consistent and predictable normalization ``window'' during which perfusion and subsequent drug delivery is optimal. This is largely due to the non-linearity in the system, and the inability to distinguish the effects of decreased vessel leakiness from those due to network structural changes in clinical trials or animal studies. We have developed a mathematical model to calculate blood flow in complex tumor networks imaged by two-photon microscopy. The model incorporates the necessary and sufficient components for addressing the problem of normalization of tumor vasculature: i) lattice-Boltzmann calculations of the full flow field within the vasculature and within the tissue, ii) diffusion and convection of soluble species such as oxygen or drugs within vessels and the tissue domain, iii) distinct and spatially-resolved vessel hydraulic conductivities and permeabilities for each species, iv) erythrocyte particles advecting in the flow and delivering oxygen with real oxygen release kinetics, v) shear stress-mediated vascular remodeling. This model, guided by multi-parameter intravital imaging of tumor vessel structure

  10. Maury Journals - German Vessels

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — German vessels observations, after the 1853 Brussels Conference that set International Maritime Standards, modeled after Maury Marine Standard Observations.

  11. Reactor vessel sealing plug

    International Nuclear Information System (INIS)

    Dooley, R.A.

    1986-01-01

    This invention relates to an apparatus and method for sealing the cold leg nozzles of a nuclear reactor pressure vessel from a remote location during maintenance and inspection of associated steam generators and pumps while the pressure vessel and refueling canal are filled with water. The apparatus includes a sealing plug for mechanically sealing the cold leg nozzle from the inside of a reactor pressure vessel. The sealing plugs include a primary and a secondary O-ring. An installation tool is suspended within the reactor vessel and carries the sealing plug. The tool telescopes to insert the sealing plug within the cold leg nozzle, and to subsequently remove the plug. Hydraulic means are used to activate the sealing plug, and support means serve to suspend the installation tool within the reactor vessel during installation and removal of the sealing plug

  12. Containment vessel drain system

    Science.gov (United States)

    Harris, Scott G.

    2018-01-30

    A system for draining a containment vessel may include a drain inlet located in a lower portion of the containment vessel. The containment vessel may be at least partially filled with a liquid, and the drain inlet may be located below a surface of the liquid. The system may further comprise an inlet located in an upper portion of the containment vessel. The inlet may be configured to insert pressurized gas into the containment vessel to form a pressurized region above the surface of the liquid, and the pressurized region may operate to apply a surface pressure that forces the liquid into the drain inlet. Additionally, a fluid separation device may be operatively connected to the drain inlet. The fluid separation device may be configured to separate the liquid from the pressurized gas that enters the drain inlet after the surface of the liquid falls below the drain inlet.

  13. 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.

  14. 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.

  15. Culture of Iris Pigment Epithelial Cells on Expanded-Polytetrafluroethylene (ePTFE Substrates for the Treatment of Age-Related Macular Degeneration

    Directory of Open Access Journals (Sweden)

    S Nian

    2011-05-01

    Full Text Available Introduction: Transplantation of an intact differentiated retinal pigment epithelial (RPE cell layer may provide a means to treat Age-Related Macular Degeneration (AMD. However, harvesting RPE cells can be a technically complicated procedure. Our current work aimed to prepare intact differentiated iris pigment epithelial (IPE cell layers, which are easy to obtain and have the same embryonic origin and similar properties as RPE cells, on ePTFE substrates for transplantation purposes to rescue deteriorated photoreceptors in AMD. Methods: IPE cells isolated from rat eyes were seeded on different substrates, including fibronectin n-heptylamine (HA ePTFE substrates, HA ePTFE substrates, ePTFE substrates and fibronectin tissue culture polystyrene (TCPS as control. Cell number and morphology were assessed at each time interval. The formation of tight junction was examined by immunostaining of junction proteins. Results: An obvious increasing trend of cell number was observed in IPE cells on fibronectin n-heptylamine (HA ePTFE substrate, exhibiting heavy pigmentation and epithelial morphology. At Day 28, tight junction formation was indicated by cell-cell junctional proteins along cell borders. Conclusion: Harvested IPE cells cultured on fibronectin HA-ePTFE substrates can differentiate and form a cell monolayer that may be suitable for transplantation.

  16. Experience of usage of forming rings and protective caps made of PTFE on the single-component implants

    Directory of Open Access Journals (Sweden)

    S. A. Chertov

    2014-04-01

    Full Text Available Relevance. The main reason that limits the usage of single-component implants, as compared with collapsible (two-component implants is the high risk of infectious and inflammatory complications in the postoperative period and problems in prosthetics in the esthetically important areas. Therefore, the usage of elements that contribute to healing of the mucous membrane in the early stages of implantation is particularly up-to-date. Work objective is to determine the clinical effectiveness of usage of forming rings and protective caps made of PTFE on the single-component implants in the prevention of peri-implant pathology on a one-step surgical implantation. Materials and methods of the investigation. For this work we used the treatment results of 24 patients with various dentition defects. According to the single-component implant procedure 52 single-component implants were mounted. The head of monolithic implants (38 p. were isolated by rings or caps made of PTFE. For comparison, 14 implants remained bare for 2-6 weeks before the temporary prosthesis. Postoperatively, subjective feelings were noted in patients, the presence or absence of pain complaints during the examination and palpation, the nature and extent of edema, the phenomena of inflammation around the implant neck were checked. At the stage of sutures removal the degree of soft plaque deposits on the healing elements and titanium implant heads was assessed. Results of the investigation and their discussion. No effects of mucosal hyperemia around the supporting elements made of PTFE were revealed, there was no soft and hard plaque on the rings and caps in most patients of the main group. In patients of the control group, on the contrary, the appearance of the biofilm that covered the head and the implant shoulder on all abutments, which were not protected by a ring or cap, was noted. The healing period of mucous membrane in patients of the control group was longer, the quality of

  17. High energy electron beams characterization using CaSO{sub 4}:Dy+PTFE Phosphors for clinical therapy applications

    Energy Technology Data Exchange (ETDEWEB)

    Rivera, T., E-mail: trivera@ipn.mx [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada-Legaria, IPN. Av. Legaria 694, Col. Irrigacion. 11500 Mexico DF (Mexico); Espinoza, A.; Von, S.M. [Centro Estatal de Cancerologia de los Servicios de Salud de Nayarit, Enfermeria S/n, Fracc, Fray Junipero Serra, 63169 Tepic Nay (Mexico); Alvarez, R.; Jimenez, Y. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada-Legaria, IPN. Av. Legaria 694, Col. Irrigacion. 11500 Mexico DF (Mexico)

    2012-07-15

    In the present work high energy electron beam dosimetry from linear accelerator (LINACs) for clinical applications using dysprosium doped calcium sulfate embedded in polytetrafluorethylene (CaSO{sub 4}:Dy+PTFE) was studied. The irradiations were carried out using high electron beams (6 to 18 MeV) from a linear accelerator (LINAC) Varian, CLINAC 2300C/D, for clinical practice purpose. The electron irradiations were obtained using the water solid in order to guarantee electronic equilibrium conditions (EEC). Field shaping for electron beams was obtained with electron cones. Glow curve and other thermoluminescent characteristics of CaSO{sub 4}:Dy+PTFE were conducted under high electrons beams irradiations. The TL response of the pellets showed an intensity peak centered at around 215 Degree-Sign C. TL response of CaSO{sub 4}:Dy+PTFE as a function of high electron absorbed dose showed a linearity in a wide range. To obtain reproducibility characteristic, a set of pellets were exposed repeatedly for the same electron absorbed dose. The results obtained in this study can suggest the applicability of CaSO{sub 4}:Dy+PTFE pellets for high electron beam dosimetry, provided fading is correctly accounted for. - Highlights: Black-Right-Pointing-Pointer Developing of CaSO{sub 4}:Dy to electron beams dosimetry. Black-Right-Pointing-Pointer Characterization of caSO{sub 4}:Dy to radiation safety in LINACs. Black-Right-Pointing-Pointer TL characteristics of CaSO{sub 4}:Dy for electron beams quality control.

  18. Electrostatic Properties of PE and PTFE Subjected to Atmospheric Pressure Plasma Treatment; Correlation of Experimental Results with Atomistic Modeling

    Science.gov (United States)

    Trigwell, Steve; Boucher, Derrick; Calle, Carlos

    2006-01-01

    The use of an atmospheric pressure glow discharge (APGD) plasma was used at KSC to increase the hydrophilicity of spaceport materials to enhance their surface charge dissipation and prevent possible ESD in spaceport operations. Significant decreases in charge decay times were observed after tribocharging the materials using the standard KSC tribocharging test. The polarity and amount of charge transferred was dependent upon the effective work function differences between the respective materials. In this study, polyethylene (PE) and polytetrafluoroethylene (PTFE) were exposed to a He+O2 APGD. The pre and post treatment surface chemistry was analyzed by X-ray photoelectron spectroscopy and contact angle measurements. Semi-empirical and ab initio calculations were performed to correlate the experimental results with some plausible molecular and electronic structure features of the oxidation process. For the PE, significant surface oxidation was observed, as indicated by XPS showing C-O, C=O, and O-C=O bonding, and a decrease in the surface contact angle from 98.9 deg to 61.2 deg. For the PTFE, no C-O bonding appeared and the surface contact angle increased indicating the APGD only succeeded in cleaning the PTFE surface without affecting the surface structure. The calculations using the PM3 and DFT methods were performed on single and multiple oligomers to simulate a wide variety of oxidation scenarios. Calculated work function results suggest that regardless of oxidation mechanism, e.g. -OH, =0 or a combination thereof, the experimentally observed levels of surface oxidation are unlikely to lead to a significant change in the electronic structure of PE and that its increased hydrophilic properties are the primary reason for the observed changes in its electrostatic behavior. The calculations for PTFE argue strongly against significant oxidation of that material, as confirmed by the XPS results.

  19. Filtration of Oil-furnace Carbon Black Dust Particles from the Tail Gases by Filter Bags With PTFE Membrane

    Directory of Open Access Journals (Sweden)

    Čuzela, D.

    2010-01-01

    Full Text Available During the industrial production of oil furnace carbon black, tail gases containing oil-furnace carbon black dust particles are emitted to the atmosphere. In the carbon black plant, Petrokemija d. d., there are six exhaust stacks for tail gases. Each of them has installed process equipment for cleaning tail gases. Efficiency of cleaning mainly depends on equipment construction and cleaning technology. The vicinity of the town, quality of the air in the region of Kutina, regarding floating particles PM10, and corporate responsibility for further enviromental improvement, imposes development of new methods that will decrease the emmision of oil-furnace carbon black dust particles in the air. Combining centrifugal percipitator and filter, special construction of cyclofilter for filtration of oil-furnace carbon black dust particles from tail gases by using PTFE (polytetrafluoroethylene membrane filter bags, was designed. Developed filtration technique provides η = 99.9 % efficiency of filtration. Construction part of the filter contains the newest generation of PTFE membrane filter bags with the ability of jet pulse cleaning. Using the PTFE membrane filter bags technology, filtration efficiency for oil-furnace carbon black dust particles in tail gases of maximum γ=5mgm-3can be achieved. The filtration efficiency was monitored continuously measuring the concentration of the oil-furnace carbon black dust particles in the tail gases with the help of in situ electronic probe. The accomplished filtration technology is the base for the installation of the PTFE membrane filter bags in the main operation filters which will provide better protection of the air in the town of Kutina against floating particles PM10.

  20. Effect of antithrombotic agents on the patency of PTFE-Covered stents in the inferior vena cava: An experimental study

    International Nuclear Information System (INIS)

    Makutani, Shiro; Kichikawa, Kimihiko; Uchida, Hideo; Maeda, Munehiro; Konishi, Noboru; Hiasa, Yoshio; Yoshikawa, Tomohiro; Kimura, Yukio

    1999-01-01

    Purpose: To evaluate the efficacy of antithrombotic agents in the prevention of stenosis of polytetrafluororethylene (PTFE)-covered stents in the venous system.Methods: Spiral Z stents covered with PTFE (PTFE-covered stents) were placed in the inferior vena cava (IVC) of 34 dogs. Nineteen dogs, used as a control group, were sacrificed at 2, 4, and 12 weeks. Fifteen dogs, previously given antithrombotic agents [cilostazol (n=5), warfarin potassium (n=5), cilostazol plus warfarin potassium (n=5)] were sacrificed at 4 weeks, and then examined angiographically and histopathologically. The effect of the antithrombotic agents was compared between groups.Results: The patency rate of the antithrombotic agent group was 93% (14/15), which was higher than the control group rate of 63% (12/19). The mean stenosis rate of the patent stent at both ends and at the midportion was lower at 4 weeks in the antithrombotic agent group than in the control group. In particular, the mean stenosis rate in the cilostazol plus warfarin potassium group was significantly lower than the control group (Tukey's test, p < 0.05). The mean neointimal thickness of the patent stent at both ends and at the midportion was thinner at 4 weeks in the antithrombotic agent group than in the control group. In particular, the thickness of the neointima in the cilostazol plus warfarin potassium group was significantly decreased when compared with the control group (Tukey's test p < 0.05). At 4 weeks, endothelialization in the antithrombotic agent group tended to be almost identical to that in the control group.Conclusion: The present study suggests that administration of an antithrombotic agent is an effective way of preventing the stenosis induced by a neointimal thickening of PTFE-covered stents in the venous system.

  1. Ridge Preservation Comparing a Nonresorbable PTFE Membrane to a Resorbable Collagen Membrane: A Clinical and Histologic Study in Humans.

    Science.gov (United States)

    Arbab, Hussain; Greenwell, Henry; Hill, Margaret; Morton, Dean; Vidal, Ricardo; Shumway, Brian; Allan, Nicholas D

    2016-02-01

    The primary aim of this randomized, controlled, blinded clinical trial was to compare the effect of a resorbable collagen membrane (CM group) versus a nonresorbable high-density polytetrafluoroethylene membrane (PTFE group) on the clinical and histologic outcomes of a ridge preservation procedure. All 24 sites received an intrasocket cancellous allograft and a buccal overlay bovine derived xenograft. The change in horizontal crestal ridge width was -1.4 ± 1.2 mm for the CM group, whereas the PTFE group lost -2.2 ± 1.5 mm, which was not statistically significant between groups (P > 0.05). Vertical ridge height change was -1.2 ± 1.5 for the CM group, whereas the PTFE group lost -0.5 ± 1.6, which was not significantly different between groups (P > 0.05). The percent vital bone was similar and not significantly different between groups. Primary closure was not obtained and the exposed membrane portion over the socket opening healed with keratinized tissue. The choice of a resorbable versus a nonresorbable barrier membrane did not affect the clinical or the histologic outcome of ridge preservation treatment.

  2. On the potential for fibronectin/phosphorylcholine coatings on PTFE substrates to jointly modulate endothelial cell adhesion and hemocompatibility properties.

    Science.gov (United States)

    Montaño-Machado, Vanessa; Chevallier, Pascale; Mantovani, Diego; Pauthe, Emmanuel

    2015-01-01

    The use of biomolecules as coatings on biomaterials is recognized to constitute a promising approach to modulate the biological response of the host. In this work, we propose a coating composed by 2 biomolecules susceptible to provide complementary properties for cardiovascular applications: fibronectin (FN) to enhance endothelialization, and phosphorylcholine (PRC) for its non thrombogenic properties. Polytetrafluoroethylene (PTFE) was selected as model substrate mainly because it is largely used in cardiovascular applications. Two approaches were investigated: 1) a sequential adsorption of the 2 biomolecules and 2) an adsorption of the protein followed by the grafting of phosphorylcholine via chemical activation. All coatings were characterized by immunofluorescence staining, X-Ray Photoelectron Spectroscopy and Scanning Electron Microscopy analyses. Assays with endothelial cells showed improvement on cell adhesion, spreading and metabolic activity on FN-PRC coatings compared with the uncoated PTFE. Platelets adhesion and activation were both reduced on the coated surfaces when compared with uncoated PTFE. Moreover, clotting time tests exhibited better hemocompatibility properties of the surfaces after a sequential adsorption of FN and PRC. In conclusion, FN-PRC coating improves cell adhesion and non-thrombogenic properties, thus revealing a certain potential for the development of this combined deposition strategy in cardiovascular applications.

  3. Socket Preservation with d-PTFE Membrane: Histologic Analysis of the Newly Formed Matrix at Membrane Removal.

    Science.gov (United States)

    Laurito, Domenico; Cugnetto, Riccardo; Lollobrigida, Marco; Guerra, Fabrizio; Vestri, Annarita; Gianno, Francesca; Bosco, Sandro; Lamazza, Luca; De Biase, Alberto

    This study aimed to evaluate the efficacy of an exposed high-density polytetrafluoroethylene (d-PTFE) membrane in preventing epithelial migration in postextraction sockets. For this purpose, a histologic description of the newly formed soft tissue underlying the membrane is presented. The periodontal status of the adjacent teeth was also evaluated to assess the gingival response. Ten premolar extraction sockets were treated. After tooth extraction, the sockets were filled with nanocrystalline hydroxyapatite and covered with d-PTFE membranes. Subperiosteal pockets were created to ensure the stability of the membranes. Membranes were left intentionally exposed and were atraumatically removed after 28 days. At that time, a bioptic specimen of the newly formed soft tissue under the membranes was taken. All the histologic samples showed a dense connective tissue without epithelial cells and no signs of foreign body reaction. No significant variation of the periodontal indices was observed on the teeth adjacent to the extraction sites. The study results indicate that exposed d-PTFE membranes can prevent epithelial migration in healing sockets without consequences on the periodontal health.

  4. Stress Analysis and Fatigue Behaviour of PTFE-Bronze Layered Journal Bearing under Real-Time Dynamic Loading

    Science.gov (United States)

    Duman, M. S.; Kaplan, E.; Cuvalcı, O.

    2018-01-01

    The present paper is based on experimental studies and numerical simulations on the surface fatigue failure of the PTFE-bronze layered journal bearings under real-time loading. ‘Permaglide Plain Bearings P10’ type journal bearings were experimentally tested under different real time dynamic loadings by using real time journal bearing test system in our laboratory. The journal bearing consists of a PTFE-bronze layer approximately 0.32 mm thick on the steel support layer with 2.18 mm thick. Two different approaches have been considered with in experiments: (i) under real- time constant loading with varying bearing widths, (ii) under different real-time loadings at constant bearing widths. Fatigue regions, micro-crack dispersion and stress distributions occurred at the journal bearing were experimentally and theoretically investigated. The relation between fatigue region and pressure distributions were investigated by determining the circumferential pressure distribution under real-time dynamic loadings for the position of every 10° crank angles. In the theoretical part; stress and deformation distributions at the surface of the journal bearing analysed by using finite element methods to determine the relationship between stress and fatigue behaviour. As a result of this study, the maximum oil pressure and fatigue cracks were observed in the most heavily loaded regions of the bearing surface. Experimental results show that PTFE-Bronze layered journal bearings fatigue behaviour is better than the bearings include white metal alloy.

  5. 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.

  6. Experimental Study on Impact-Induced Reaction Characteristics of PTFE/Ti Composites Enhanced by W Particles

    Directory of Open Access Journals (Sweden)

    Yan Li

    2017-02-01

    Full Text Available Metal/fluoropolymer composites are a category of energetic structural materials that release energy through exothermic chemical reactions initiated under highly dynamic loadings. In this paper, the chemical reaction mechanism of PTFE (polytetrafluoroethylene/Ti/W composites is investigated through thermal analysis and composition analysis. These composites undergo exothermic reactions at 510 °C to 600 °C, mainly producing TiFx. The tungsten significantly reduces the reaction heat due to its inertness. In addition, the dynamic compression properties and impact-induced reaction behaviors of PTFE/Ti/W composites with different W content prepared by pressing and sintering are studied using Split Hopkinson Pressure Bar and high speed photography. The results show that both the mechanical strength and the reaction degree are significantly improved with the increasing strain rate. Moreover, as W content increases, the mechanical strength is enhanced, but the elasticity/plasticity is decreased. The PTFE/Ti/W composites tend to become more inert with the increasing W content, which is reflected by the reduced reaction degree and the increased reaction threshold for the impact ignition.

  7. Superhydrophobic photocatalytic PTFE – Titania coatings deposited by reactive pDC magnetron sputtering from a blended powder target

    Energy Technology Data Exchange (ETDEWEB)

    Ratova, Marina, E-mail: marina_ratova@hotmail.com; Kelly, Peter J.; West, Glen T.

    2017-04-01

    The production of photocatalytic coatings with superhydrophobic properties, as opposed to the conventional hydrophilic properties, is desirable for the prevention of adhesion of contaminants to photocatalytic surfaces with subsequent deterioration of photocatalytic properties. In this work polytetrafluoroethylene (PTFE) – TiO{sub 2} composite thin films were deposited using a novel method of reactive pulsed direct current (pDC) magnetron sputtering of a blended PTFE – titanium oxide powder target. The surface characteristics and photocatalytic properties of the deposited composite coatings were studied. The as-deposited coatings were annealed at 523 K in air and analysed with Raman spectroscopy, optical profilometry and scanning electron microscopy. Hydrophobicity was assessed though measurements of water contact angles, and photocatalytic properties were studied via methylene blue dye degradation under UV irradiation. It was found that variations of gas flow and, hence, process pressures allowed deposition of samples combining superhydrophobicity with stable photocatalytic efficiency under UV light irradiation. Reversible wettability behaviour was observed with the alternation of light-dark cycles. - Highlights: • PTFE-TiO{sub 2} coatings were deposited by pDC reactive magnetron sputtering. • Blended powder target was used for coatings deposition. • Deposited coatings combined superhydrophobic and photocatalytic properties. • Under UV irradiation coatings exhibited reversible wettability.

  8. 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

  9. NCSX Vacuum Vessel Fabrication

    International Nuclear Information System (INIS)

    Viola ME; Brown T; Heitzenroeder P; Malinowski F; Reiersen W; Sutton L; Goranson P; Nelson B; Cole M; Manuel M; McCorkle D.

    2005-01-01

    The National Compact Stellarator Experiment (NCSX) is being constructed at the Princeton Plasma Physics Laboratory (PPPL) in conjunction with the Oak Ridge National Laboratory (ORNL). The goal of this experiment is to develop a device which has the steady state properties of a traditional stellarator along with the high performance characteristics of a tokamak. A key element of this device is its highly shaped Inconel 625 vacuum vessel. This paper describes the manufacturing of the vessel. The vessel is being fabricated by Major Tool and Machine, Inc. (MTM) in three identical 120 o vessel segments, corresponding to the three NCSX field periods, in order to accommodate assembly of the device. The port extensions are welded on, leak checked, cut off within 1-inch of the vessel surface at MTM and then reattached at PPPL, to accommodate assembly of the close-fitting modular coils that surround the vessel. The 120 o vessel segments are formed by welding two 60 o segments together. Each 60 o segment is fabricated by welding ten press-formed panels together over a collapsible welding fixture which is needed to precisely position the panels. The vessel is joined at assembly by welding via custom machined 8-inch (20.3 cm) wide spacer ''spool pieces''. The vessel must have a total leak rate less than 5 X 10 -6 t-l/s, magnetic permeability less than 1.02(micro), and its contours must be within 0.188-inch (4.76 mm). It is scheduled for completion in January 2006

  10. Radioactive waste processing vessel

    International Nuclear Information System (INIS)

    Hayashi, Masaru; Suzuki, Osamu; Ishizaki, Kanjiro.

    1987-01-01

    Purpose: To obtain a vessel of a reduced weight and with no external leaching of radioactive materials. Constitution: The vessel main body is constituted, for example, with light weight concretes or foamed concretes, particularly, foamed concretes containing fine closed bubbles in the inside. Then, layers having dense texture made of synthetic resin such as polystylene, vinylchloride resin, etc. or metal plate such as stainless plate are integrally disposed to the inner surface of the vessel main body. The cover member also has the same structure. (Sekiya, K.)

  11. Tempest in a vessel

    International Nuclear Information System (INIS)

    Barre, Bertrand

    2015-01-01

    As the ASN made some statements about anomalies of carbon content in the EPR vessel bottom and top, the author recalls and comments some technical issues to better understand the information published on this topic. He notably addresses the role of the vessel, briefly indicates its operating conditions, shape and structure, and mechanical components for the top, its material and mechanical properties, and test samples used to assess mechanical properties. He also comments the phenomenon of radio-induced embrittlement, the vessel manufacturing process, and evokes the applicable regulations. He quotes and comments statements made by the ASN and Areva which evoke further assessments of the concerned components

  12. Cheboygan Vessel Base

    Data.gov (United States)

    Federal Laboratory Consortium — Cheboygan Vessel Base (CVB), located in Cheboygan, Michigan, is a field station of the USGS Great Lakes Science Center (GLSC). CVB was established by congressional...

  13. High Performance Marine Vessels

    CERN Document Server

    Yun, Liang

    2012-01-01

    High Performance Marine Vessels (HPMVs) range from the Fast Ferries to the latest high speed Navy Craft, including competition power boats and hydroplanes, hydrofoils, hovercraft, catamarans and other multi-hull craft. High Performance Marine Vessels covers the main concepts of HPMVs and discusses historical background, design features, services that have been successful and not so successful, and some sample data of the range of HPMVs to date. Included is a comparison of all HPMVs craft and the differences between them and descriptions of performance (hydrodynamics and aerodynamics). Readers will find a comprehensive overview of the design, development and building of HPMVs. In summary, this book: Focuses on technology at the aero-marine interface Covers the full range of high performance marine vessel concepts Explains the historical development of various HPMVs Discusses ferries, racing and pleasure craft, as well as utility and military missions High Performance Marine Vessels is an ideal book for student...

  14. 2011 Vessel Density

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Automatic Identification Systems (AIS) are a navigation safety device that transmits and monitors the location and characteristics of many vessels in U.S. and...

  15. 2011 Fishing Vessel Density

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Automatic Identification Systems (AIS) are a navigation safety device that transmits and monitors the location and characteristics of many vessels in U.S. and...

  16. 2013 Tanker Vessel Density

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Automatic Identification Systems (AIS) are a navigation safety device that transmits and monitors the location and characteristics of many vessels in U.S. and...

  17. Maury Journals - US Vessels

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — U.S. vessels observations, after the 1853 Brussels Conference that set International Maritime Standards, modeled after Maury Marine Standard Observations.

  18. Coastal Logbook Survey (Vessels)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains catch (landed catch) and effort for fishing trips made by vessels that have been issued a Federal permit for the Gulf of Mexico reef fish,...

  19. In-vessel tritium

    International Nuclear Information System (INIS)

    Ueda, Yoshio; Ohya, Kaoru; Ashikawa, Naoko; Ito, Atsushi M.; Kato, Daiji; Kawamura, Gakushi; Takayama, Arimichi; Tomita, Yukihiro; Nakamura, Hiroaki; Ono, Tadayoshi; Kawashima, Hisato; Shimizu, Katsuhiro; Takizuka, Tomonori; Nakano, Tomohide; Nakamura, Makoto; Hoshino, Kazuo; Kenmotsu, Takahiro; Wada, Motoi; Saito, Seiki; Takagi, Ikuji; Tanaka, Yasunori; Tanabe, Tetsuo; Yoshida, Masafumi; Toma, Mitsunori; Hatayama, Akiyoshi; Homma, Yuki; Tolstikhina, Inga Yu.

    2012-01-01

    The in-vessel tritium research is closely related to the plasma-materials interaction. It deals with the edge-plasma-wall interaction, the wall erosion, transport and re-deposition of neutral particles and the effect of neutral particles on the fuel recycling. Since the in-vessel tritium shows a complex nonlinear behavior, there remain many unsolved problems. So far, behaviors of in-vessel tritium have been investigated by two groups A01 and A02. The A01 group performed experiments on accumulation and recovery of tritium in thermonuclear fusion reactors and the A02 group studied theory and simulation on the in-vessel tritium behavior. In the present article, outcomes of the research are reviewed. (author)

  20. Reactor pressure vessel support

    International Nuclear Information System (INIS)

    Butti, J.P.

    1977-01-01

    A link and pin support system provides the primary vertical and lateral support for a nuclear reactor pressure vessel without restricting thermally induced radial and vertical expansion and contraction. (Auth.)

  1. 2013 Cargo Vessel Density

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Automatic Identification Systems (AIS) are a navigation safety device that transmits and monitors the location and characteristics of many vessels in U.S. and...

  2. 2013 Fishing Vessel Density

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Automatic Identification Systems (AIS) are a navigation safety device that transmits and monitors the location and characteristics of many vessels in U.S. and...

  3. 2013 Vessel Density

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Automatic Identification Systems (AIS) are a navigation safety device that transmits and monitors the location and characteristics of many vessels in U.S. and...

  4. Ocean Station Vessel

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Ocean Station Vessels (OSV) or Weather Ships captured atmospheric conditions while being stationed continuously in a single location. While While most of the...

  5. Vessel Sewage Discharges

    Science.gov (United States)

    Vessel sewage discharges are regulated under Section 312 of the Clean Water Act, which is jointly implemented by the EPA and Coast Guard. This homepage links to information on marine sanitation devices and no discharge zones.

  6. Investigation on Mechanical Properties and Reaction Characteristics of Al-PTFE Composites with Different Al Particle Size

    Directory of Open Access Journals (Sweden)

    Jia-xiang Wu

    2018-01-01

    Full Text Available Al-PTFE (aluminum-polytetrafluoroethylene serves as one among the most promising reactive materials (RMs. In this work, six types of Al-PTFE composites with different Al particle sizes (i.e., 50 nm, 1∼2 μm, 6∼7 μm, 12∼14 μm, 22∼24 μm, and 32∼34 μm were prepared, and quasistatic compression and drop weight tests were conducted to characterize the mechanical properties and reaction characteristics of Al-PTFE composites. The reaction phenomenon and stress-strain curves were recorded by a high-speed camera and universal testing machine. The microstructure of selected specimens was anatomized through adopting a scanning electron microscope (SEM to correlate the mesoscale structural characteristics to their macroproperties. As the results indicated, in the case of quasistatic compression, the strength of the composites was decreased (the yield strength falling from 22.7 MPa to 13.6 MPa and the hardening modulus declining from 33.3 MPa to 25 MPa with the increase of the Al particle size. The toughness rose firstly and subsequently decreased and peaked as 116.42 MJ/m3 at 6∼7 μm. The reaction phenomenon occurred only in composites with the Al particle size less than 10 μm. In drop weight tests, six types of specimens were overall reacted. As the Al particle size rose, the ignition energy of the composites enhanced and the composites turned out to be more insensitive to reaction. In a lower strain rate range (10−2·s−1∼102·s−1, Al-PTFE specimens take on different mechanical properties and reaction characteristics in the case of different strain rates. The formation of circumferential open cracks is deemed as a prerequisite for Al-PTFE specimens to go through a reaction.

  7. Novel phosphate-grafted ePTFE copolymers for optimum in vitro mineralization

    International Nuclear Information System (INIS)

    Wentrup-Byrne, Edeline; Suzuki, Shuko; Groendahl, Lisbeth; Suwanasilp, Juthakarn Jessica

    2010-01-01

    Surface modification via graft copolymerization is an attractive method for optimizing polymers used in biomedical applications. We developed a novel method using a mixed solvent system (either water and dichloromethane (DCM) or water, methanol and DCM) consisting of two solvent phases for grafting 2-(methacryloyloxy)ethyl phosphate onto expanded polytetrafluoroethylene (ePTFE). This new method resulted in the fabrication of grafted membranes with greater grafting extents (GEs) (as evaluated from x-ray photoelectron spectroscopy (XPS)) in the organic phase than those obtained when grafting was carried out in a single phase. It also made it possible to graft in the aqueous phase, a process that is otherwise inhibited by the concomitant formation of large amounts of highly crystalline homopolymer. Thorough characterization of the grafted membranes using gravimetric, XPS and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) not only permitted evaluation of the grafting outcomes but also made it possible to analyze their dependence on monomer concentration and solvent composition. A selection of membranes was tested for their in vitro mineralization capacity using simulated body fluid. It was found that an 'ideal' mineralization outcome, i.e. a uniform coating of carbonated hydroxyapatite (cHAP) formed on the sample grafted in the aqueous phase of the water/DCM two-phase solvent system. A detailed discussion bringing together these results, as well as results from a series of earlier studies, allows conclusions regarding polymer chemistry and the topology necessary for cHAP mineralization.

  8. Circularly Polarized S Band Dual Frequency Square Patch Antenna Using Glass Microfiber Reinforced PTFE Composite

    Directory of Open Access Journals (Sweden)

    M. Samsuzzaman

    2014-01-01

    Full Text Available Circularly polarized (CP dual frequency cross-shaped slotted patch antenna on 1.575 mm thick glass microfiber reinforced polytetrafluoroethylene (PTFE composite material substrate is designed and fabricated for satellite applications. Asymmetric cross-shaped slots are embedded in the middle of the square patch for CP radiation and four hexagonal slots are etched on the four sides of the square patch for desired dual frequency. Different substrate materials have been analysed to achieve the desired operating band. The experimental results show that the impedance bandwidth is approximately 30 MHz (2.16 GHz to 2.19 GHz for lower band and 40 MHz (3.29 GHz to 3.33 GHz for higher band with an average peak gain of 6.59 dBiC and 5.52 dBiC, respectively. Several optimizations are performed to obtain the values of the antenna physical parameters. Moreover, the proposed antenna possesses compactness, light weight, simplicity, low cost, and circularly polarized. It is an attractive candidate for dual band satellite antennas where lower band can be used for uplink and upper band can be used for downlink.

  9. The Study of the Composite Material Go/CF/PTFE Tribological Property

    Directory of Open Access Journals (Sweden)

    Wang Li-hu

    2017-01-01

    Full Text Available In this paper, the composite material Go/CF/PTFE tribological property was studied. The test of its mechanical property, and the fabrication of the filled PTEE composite material sample which is based on the technology of cold press molding and sinter molding proved that adding Go and CF moderately to the composite material was an efficient way to improve its mechanical property. Meanwhile the process of friction and wear trial and SEM analysis results of the micro-structure of wear pattern proved that the addition of the Go and CF tremendously improved the anti-wear property and that after the addition the plowing effect which took place on the material surface would turn into a kind of mixed wear effect that includes plowing effect and fatigue wear. Working as pinning and bridging, the Go which distributing uniformly in the matrix was able to improve the resistance and substantially resisted the crack propagation, therefore to a certain degree enhanced the intensity of composite material and prolong its lifespan.

  10. Analysis of abrasive wear behavior of PTFE composite using Taguchi’s technique

    Directory of Open Access Journals (Sweden)

    Yusuf Şahin

    2015-12-01

    Full Text Available Polymeric composites are widely used for structural, aerospace, and automobile sectors due to their good combination of high specific strength and specific modulus. These two main characteristics make these materials attractive, compared to conventional materials like metal or alloy ones. Some of their typical benefits include easy processing, corrosion resistance, low friction, and damping of noise and vibrations. Wear behavior of Polytetrafluoroethylenes (PTFE and its composites including glass-filled composites and carbon-filled composites are investigated using a pin-on-disc configuration. A plan of experiments in terms of Taguchi technique is carried out to acquire data in controlled way. An orthogonal array (L9 and the analysis of variance are employed to investigate the influence of process parameters on the wear of these composites. Volume loss increased with abrasive size, load, and distance. Furthermore, specific wear rate decreased with increasing grit size, load, sliding distance, whereas, slightly with compressive strength. Optimal process parameters, which minimize the volume loss, were the factor combinations of L1, G3, D1, and C3. Confirmation experiments were conducted to verify the optimal testing parameters. It was found that in terms of volume loss, there was a good agreement between the estimated and the experimental value of S/N ratio with an error of 1.604%. Moreover, abrasive size, load, and sliding distance exerted a great effect on the specific wear rate, at 51.14, 27.77, and 14.70%, respectively.

  11. Surface modifying of microporous PTFE capillary for bilirubin removing from human plasma and its blood compatibility

    International Nuclear Information System (INIS)

    Jin Gu; Yao Qizhi; Zhang Shanzi; Zhang Lei

    2008-01-01

    In this study, human serum albumin (HSA) was covalently immobilized onto the inner surface of microporous poly(tetrafluoroethylene) (MPTFE) capillaries for direct bilirubin removal from human plasma. To obtain active binding sites for HSA, the MPTFE capillaries were chemically functionalized by using a coating of poly(vinyl alcohol) (PVA)-glycidyl methacrylate (GMA) copolymers. Characterization of grafted MPTFE capillaries was verified by XPS, Fourier transform infrared spectroscopy (FT-IR), scanning electronic microscopy (SEM). Non-specific adsorption on the PVA-GMA coated capillary remains low (< 0.38 mg bilirubin/g), and higher affinity adsorption capacity, of up to 73.6 mg bilirubin/g polymer was obtained after HSA is immobilized. Blood compatibility of the grafted MPTFE capillary was evaluated by SEM and platelet rich plasma (PRP) contacting experiments. The experimental data on blood compatibility indicated that PVA-coated and PVA-GMA-HSA coated PTFE capillary showed a sharp suppress on platelets adhesion. The proposed method has the potential of serving in bilirubin removal in clinical application

  12. Reflectance measurements of PTFE, Kapton, and PEEK for xenon scintillation light for the LZ detector.

    Science.gov (United States)

    Arthurs, M.; Batista, E.; Haefner, J.; Lorenzon, W.; Morton, D.; Neff, A.; Okunawo, M.; Pushkin, K.; Sander, A.; Stephenson, S.; Wang, Y.; LZ Collaboration

    2017-01-01

    LZ (LUX-Zeplin) is an international collaboration that will look for dark matter candidates, WIMPs (Weakly Interacting Massive Particles), through direct detection by dual-phase time projection chamber (TPC) using liquid xenon. The LZ detector will be located nearly a mile underground at SURF, South Dakota, shielded from cosmic background radiation. Seven tons active mass of liquid xenon will be used for detecting the weak interaction of WIMPs with ordinary matter. Over three years of operation it is expected to reach the ultimate sensitivity of 2x10-48 cm2 for a WIMP mass of 50 GeV. As for many other rare event searches, high light collection efficiency is essential for LZ detector. Moreover, in order to achieve greater active volume for detection as well as reduce potential backgrounds, thinner detector walls without significant loss in reflectance are desired. Reflectance measurements of polytetrafluoroethylene (PTFE), Kapton, and PEEK for xenon scintillation light (178 nm), conducted at the University of Michigan using the Michigan Xenon Detector (MiX) will be presented. The University of Michigan, LZ Collaboration, The US Department of Energy.

  13. Drop evaporation on superhydrophobic PTFE surfaces driven by contact line dynamics.

    Science.gov (United States)

    Ramos, S M M; Dias, J F; Canut, B

    2015-02-15

    In the present study, we experimentally study the evaporation modes and kinetics of sessile drops of water on highly hydrophobic surfaces (contact angle ∼160°), heated to temperatures ranging between 40° and 70 °C. These surfaces were initially constructed by means of controlled tailoring of polytetrafluoroethylene (PTFE) substrates. The evaporation of droplets was observed to occur in three distinct phases, which were the same for the different substrate temperatures. The drops started to evaporate in the constant contact radius (CCR) mode, then switched to a more complex mode characterized by a set of stick-slip events accompanied by a decrease in contact angle, and finally shifted to a mixed mode in which the contact radius and contact angle decreased simultaneously until the drops had completely evaporated. It is shown that in the case of superhydrophobic surfaces, the energy barriers (per unit length) associated with the stick-slip motion of a drop ranges in the nJ m(-1) scale. Furthermore, analysis of the evaporation rates, determined from experimental data show that, even in the CCR mode, a linear relationship between V(2/3) and the evaporation time is verified. The values of the evaporation rate constants are found to be higher in the pinned contact line regime (the CCR mode) than in the moving contact line regime. This behavior is attributed to the drop's higher surface to volume ratio in the CCR mode. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Higher de novo synthesized fatty acids and lower omega 3-and omega 6-long-chain polyunsaturated fatty acids in umbilical vessels of women with preeclampsia and high fish intakes

    NARCIS (Netherlands)

    Huiskes, Victor J. B.; Kuipers, Remko S.; Velzing-Aarts, Francien V.; Dijck-Brouwer, D. A. Janneke; van der Meulen, Jan; Muskiet, Frits A. J.

    2009-01-01

    Umbilical veins (UV) and arteries (UA) of preeclamptic women in Curacao harbor lower long-chain polyunsaturated fatty acids (LCP). The present aim was to test these findings in Mwanza (Tanzania), whose inhabitants have high LCP omega 3 and LCP omega 6 intakes from Lake Victoria fish. Women with

  15. Reactor pressure vessel design

    International Nuclear Information System (INIS)

    Foehl, J.

    1998-01-01

    As a result of the popularity of the Agencies report 'Neutron Irradiation Embrittlement of Reactor Pressure Vessel Steels' of 1975, it was decided that another report on this broad subject would be of use. In this report, background and contemporary views on specially identified areas of the subject are considered as self-contained chapters, written by experts. In chapter 2, the general principles of reactor pressure vessel design are elaborated. Crack and fracture initiation and propagation are treated in some detail

  16. Graywater Discharges from Vessels

    Science.gov (United States)

    2011-11-01

    metals (e.g., cadmium, chromium, lead, copper , zinc, silver, nickel, and mercury), solids, and nutrients (USEPA, 2008b; USEPA 2010). Wastewater from... flotation ), and disinfection (using ultraviolet light) as compared to traditional Type II MSDs that use either simple maceration and chlorination, or...Coliform Naval Vessels Oceanographic Vessels Small Cruise Ships 25a Vendor 2 Hamann AG Biological Treatment with Dissolved Air Flotation and

  17. LANL Robotic Vessel Scanning

    Energy Technology Data Exchange (ETDEWEB)

    Webber, Nels W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-25

    Los Alamos National Laboratory in J-1 DARHT Operations Group uses 6ft spherical vessels to contain hazardous materials produced in a hydrodynamic experiment. These contaminated vessels must be analyzed by means of a worker entering the vessel to locate, measure, and document every penetration mark on the vessel. If the worker can be replaced by a highly automated robotic system with a high precision scanner, it will eliminate the risks to the worker and provide management with an accurate 3D model of the vessel presenting the existing damage with the flexibility to manipulate the model for better and more in-depth assessment.The project was successful in meeting the primary goal of installing an automated system which scanned a 6ft vessel with an elapsed time of 45 minutes. This robotic system reduces the total time for the original scope of work by 75 minutes and results in excellent data accumulation and transmission to the 3D model imaging program.

  18. FFTF and CRBRP reactor vessels

    International Nuclear Information System (INIS)

    Morgan, R.E.

    1977-01-01

    The Fast Flux Test Facility (FFTF) reactor vessel and the Clinch River Breeder Reactor Plant (CRBRP) reactor vessel each serve to enclose a fast spectrum reactor core, contain the sodium coolant, and provide support and positioning for the closure head and internal structure. Each vessel is located in its reactor cavity and is protected by a guard vessel which would ensure continued decay heat removal capability should a major system leak develop. Although the two plants have significantly different thermal power ratings, 400 megawatts for FFTF and 975 megawatts for CRBRP, the two reactor vessels are comparable in size, the CRBRP vessel being approximately 28% longer than the FFTF vessel. The FFTF vessel diameter was controlled by the space required for the three individual In-Vessel Handling Machines and Instrument Trees. Utilization of the triple rotating plug scheme for CRBRP refueling enables packaging of the larger CRBRP core in a vessel the same diameter as the FFTF vessel

  19. The effect of nitrogen and oxygen plasma on the wear properties and adhesion strength of the diamond-like carbon film coated on PTFE

    International Nuclear Information System (INIS)

    Ozeki, K.; Hirakuri, K.K.

    2008-01-01

    Diamond-like carbon (DLC) films were deposited on polytetrafluoroethylene (PTFE) using a radiofrequency plasma chemical vapour deposition method. Prior to DLC coating, the PTFE substrates were modified with O 2 and N 2 plasma to enhance the adhesion strength of the DLC film to the substrate. The effect of the plasma pre-treatment on the chemical composition and the surface energy of the plasma pre-treated PTFE surface was investigated by X-ray photoelectron spectroscopy (XPS) and static water contact angle measurement, respectively. A pull-out test and a ball-on-disc test were carried out to evaluate the adhesion strength and the wear properties of the DLC-coated PTFE. In the N 2 plasma pre-treatment, the XPS result indicated that defluorination and the nitrogen grafting occurred on the plasma pre-treated PTFE surface, and the water contact angle decreased with increasing the plasma pre-treatment time. In the O 2 plasma pre-treatment, no grafting of the oxygen occurred, and the water contact angle slightly increased with the treatment time. In the pull-out test, the adhesion strength of the DLC film to the PTFE substrate was improved with the plasma pre-treatment to the PTFE substrate, and N 2 plasma pre-treatment was more effective than the O 2 plasma pre-treatment. In the ball-on-disc test, the DLC film with the N 2 plasma pre-treatment showed good wear resistance, compared with that with O 2 plasma pre-treatment

  20. Acrylic vessel cleaning tests

    International Nuclear Information System (INIS)

    Earle, D.; Hahn, R.L.; Boger, J.; Bonvin, E.

    1997-01-01

    The acrylic vessel as constructed is dirty. The dirt includes blue tape, Al tape, grease pencil, gemak, the glue or residue form these tapes, finger prints and dust of an unknown composition but probably mostly acrylic dust. This dirt has to be removed and once removed, the vessel has to be kept clean or at least to be easily cleanable at some future stage when access becomes much more difficult. The authors report on the results of a series of tests designed: (a) to prepare typical dirty samples of acrylic; (b) to remove dirt stuck to the acrylic surface; and (c) to measure the optical quality and Th concentration after cleaning. Specifications of the vessel call for very low levels of Th which could come from tape residues, the grease pencil, or other sources of dirt. This report does not address the concerns of how to keep the vessel clean after an initial cleaning and during the removal of the scaffolding. Alconox is recommended as the cleaner of choice. This acrylic vessel will be used in the Sudbury Neutrino Observatory

  1. PTFE Additive and Re-annealing Effect on Thermoluminescence Response of CaSO4:Dy Derived from Co-precipitation Method

    Science.gov (United States)

    Nuraeni, Nunung; Dwi Septianto, Ricky; Iskandar, Ferry; Haryanto, Freddy; Waris, Abdul; Hiswara, Eri

    2017-07-01

    Effect of re-annealing treatment in thermoluminescence response of thermoluminescent dosimeter (TLD) CaSO4:Dy and CaSO4:Dy with PTFE (Polytetrafluoroethylene) addition was investigated. CaSO4:Dy was prepared by a co-precipitation method. The PTFE was added before re-annealing treatment which the mass ratio of CaSO4:Dy and PTFE was fixed to 2:3. The re-annealing treatments of the samples were done at temperature 700 °C for 1 hr. The obtained samples were characterized using a Fourier-transform infrared (FTIR) and X-ray diffraction (XRD) to observe the molecule bonding in sample and crystal properties, respectively. From the experimental results, it was observed that the thermoluminescence intensity of CaSO4:Dy, CaSO4:Dy re-annealed at 700 °C, and CaSO4:Dy + PTFE re-annealed at 700 °C are 57.03, 75.15, and 1191.11 nC, respectively. The intensity of 700 °C-re-annealed CaSO4:Dy increased significantly after PTFE addition.

  2. 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.

  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. Radioactive liquid containing vessel

    International Nuclear Information System (INIS)

    Sakurada, Tetsuo; Kawamura, Hironobu.

    1993-01-01

    Cooling jackets are coiled around the outer circumference of a container vessel, and the outer circumference thereof is covered with a surrounding plate. A liquid of good conductivity (for example, water) is filled between the cooling jackets and the surrounding plate. A radioactive liquid is supplied to the container vessel passing through a supply pipe and discharged passing through a discharge pipe. Cooling water at high pressure is passed through the cooling water jackets in order to remove the heat generated from the radioactive liquid. Since cooling water at high pressure is thus passed through the coiled pipes, the wall thickness of the container vessel and the cooling water jackets can be reduced, thereby enabling to reduce the cost. Further, even if the radioactive liquid is leaked, there is no worry of contaminating cooling water, to prevent contamination. (I.N.)

  5. Percutaneous Palliation of Pancreatic Head Cancer: Randomized Comparison of ePTFE/FEP–Covered Versus Uncovered Nitinol Biliary Stents

    International Nuclear Information System (INIS)

    Krokidis, Miltiadis; Fanelli, Fabrizio; Orgera, Gianluigi; Tsetis, Dimitrios; Mouzas, Ioannis; Bezzi, Mario; Kouroumalis, Elias; Pasariello, Roberto; Hatzidakis, Adam

    2011-01-01

    The purpose of this study was to compare the clinical effectiveness of expanded polytetrafluoroethylene/fluorinated-ethylene-propylene (ePTFE/FEP)–covered stents with that of uncovered nitinol stents for the palliation of malignant jaundice caused by inoperable pancreatic head cancer. Eighty patients were enrolled in a prospective randomized study. Bare nitinol stents were used in half of the patients, and ePTFE/FEP–covered stents were used in the remaining patients. Patency, survival, complications, and mean cost were calculated in both groups. Mean patency was 166.0 ± 13.11 days for the bare-stent group and 234.0 ± 20.87 days for the covered-stent group (p = 0.007). Primary patency rates at 3, 6, and 12 months were 77.5, 69.8, and 69.8% for the bare-stent group and 97.5, 92.2, and 87.6% for the covered-stent group, respectively. Mean secondary patency was 123.7 ± 22.5 days for the bare-stent group and 130.3 ± 21.4 days for the covered-stent group. Tumour ingrowth occurred exclusively in the bare-stent group in 27.5% of cases (p = 0.002). Median survival was 203.2 ± 11.8 days for the bare-stent group and 247.0 ± 20 days for the covered-stent group (p = 0.06). Complications and mean cost were similar in both groups. Regarding primary patency and ingrowth rate, ePTFE/FEP–covered stents have shown to be significantly superior to bare nitinol stents for the palliation of malignant jaundice caused by inoperable pancreatic head cancer and pose comparable cost and complications. Use of a covered stent does not significantly influence overall survival rate; nevertheless, the covered endoprosthesis seems to offer result in fewer reinterventions and better quality of patient life.

  6. Mechanical properties and the evolution of matrix molecules in PTFE upon irradiation with MeV alpha particles

    International Nuclear Information System (INIS)

    Fisher, Gregory L.; Lakis, Rollin E.; Davis, Charles C.; Szakal, Christopher; Swadener, John G.; Wetteland, Christopher J.; Winograd, Nicholas

    2006-01-01

    The morphology, chemical composition, and mechanical properties in the surface region of α-irradiated polytetrafluoroethylene (PTFE) have been examined and compared to unirradiated specimens. Samples were irradiated with 5.5 MeV 4 He 2+ ions from a tandem accelerator to doses between 1 x 10 6 and 5 x 10 10 Rad. Static time-of-flight secondary ion mass spectrometry (ToF-SIMS), using a 20 keV C 60 + source, was employed to probe chemical changes as a function of α dose. Chemical images and high resolution spectra were collected and analyzed to reveal the effects of α particle radiation on the chemical structure. Residual gas analysis (RGA) was utilized to monitor the evolution of volatile species during vacuum irradiation of the samples. Scanning electron microscopy (SEM) was used to observe the morphological variation of samples with increasing α particle dose, and nanoindentation was engaged to determine the hardness and elastic modulus as a function of α dose. The data show that PTFE nominally retains its innate chemical structure and morphology at α doses 9 Rad. At α doses ≥10 9 Rad the polymer matrix experiences increased chemical degradation and morphological roughening which are accompanied by increased hardness and declining elasticity. At α doses >10 10 Rad the polymer matrix suffers severe chemical degradation and material loss. Chemical degradation is observed in ToF-SIMS by detection of ions that are indicative of fragmentation, unsaturation, and functionalization of molecules in the PTFE matrix. The mass spectra also expose the subtle trends of crosslinking within the α-irradiated polymer matrix. ToF-SIMS images support the assertion that chemical degradation is the result of α particle irradiation and show morphological roughening of the sample with increased α dose. High resolution SEM images more clearly illustrate the morphological roughening and the mass loss that accompanies high doses of α particles. RGA confirms the supposition that

  7. Evolution of shear stress, protein expression, and vessel area in an animal model of arterial dilatation in hemodialysis grafts

    Science.gov (United States)

    Misra, Sanjay; Fu, Alex A.; Misra, Khamal D.; Glockner, James F.; Mukhopadyay, Debabrata

    2010-01-01

    Purpose To evaluate the wall shear stress, protein expression of matrix metalloproteinases-2 (MMP-2), -9 (MMP-9), and the inhibitors (tissue inhibitor of matrix metalloproteinases-1 (TIMP-1), and -2 (TIMP-2)), and vessel area over time in a porcine model for hemodialysis polytetrafluoroethylene (PTFE) grafts. Materials and methods In 21 pigs, subtotal renal infarction was performed and 28 days later, a PTFE graft was placed to connect the carotid artery to the ipsilateral jugular vein. Phase contrast MR was used to measure blood flow and vessel area at 1, 3, 7, and 14 days after graft placement. Wall shear stress was estimated from Poiseuille’s law. Animals were sacrificed at day 3 (N=7), day 7 (N=7), and day 14 (N=7) and expression of MMP-2, MMP-9, TIMP-1, and TIMP-2 were determined at the grafted and control arteries. Results The mean wall shear stress of the grafted artery was higher than the control artery at all time points (P<0.05). It peaked by day 3 and decreased by days 7–14 as the vessel area nearly doubled. By days 7–14, there was a significant increase in active MMP-2 followed by a significant increase in pro and active MMP-9 by day 14 (P<0.05, grafted artery versus control). TIMP-1 expression peaked by day 7 and then decreased while TIMP-2 expression was decreased at days 7–14. Conclusions The wall shear stress of the grafted artery peaks by day 3 with increased MMP-2 activity by days 7–14 followed by pro and active MMP-9 by day 14 and the vessel area nearly doubled. PMID:20123196

  8. Pressure vessel integrity 1991

    International Nuclear Information System (INIS)

    Bhandari, S.; Doney, R.O.; McDonald, M.S.; Jones, D.P.; Wilson, W.K.; Pennell, W.E.

    1991-01-01

    This volume contains papers relating to the structural integrity assessment of pressure vessels and piping, with special emphasis on nuclear industry applications. The papers were prepared for technical sessions developed under the sponsorship of the ASME Pressure Vessels and Piping Division Committees for Codes and Standards, Computer Technology, Design and Analysis, and Materials Fabrication. They were presented at the 1991 Pressure Vessels and Piping Division Conference in San Diego, California, June 23-27. The primary objective of the sponsoring organization is to provide a forum for the dissemination and discussion of information on development and application of technology for the structural integrity assessment of pressure vessels and piping. This publication includes contributions from authors from Australia, France, Japan, Sweden, Switzerland, the United Kingdom, and the United States. The papers here are organized in six sections, each with a particular emphasis as indicated in the following section titles: Fracture Technology Status and Application Experience; Crack Initiation, Propagation and Arrest; Ductile Tearing; Constraint, Stress State, and Local-Brittle-Zones Effects; Computational Techniques for Fracture and Corrosion Fatigue; and Codes and Standards for Fatigue, Fracture and Erosion/Corrosion

  9. The reactor vessel steels

    International Nuclear Information System (INIS)

    Bilous, W.; Hajewska, E.; Szteke, W.; Przyborska, M.; Wasiak, J.; Wieczorkowski, M.

    2005-01-01

    In the paper the fundamental steels using in the construction of pressure vessel water reactor are discussed. The properties of these steels as well as the influence of neutron irradiation on its degradation in the time of exploitation are also done. (authors)

  10. Vacuum distilling vessel

    Energy Technology Data Exchange (ETDEWEB)

    Reik, H

    1928-12-27

    Vacuum distilling vessel for mineral oil and the like, characterized by the ring-form or polyconal stiffeners arranged inside, suitably eccentric to the casing, being held at a distance from the casing by connecting members of such a height that in the resulting space if necessary can be arranged vapor-distributing pipes and a complete removal of the residue is possible.

  11. Visualization of vessel traffic

    NARCIS (Netherlands)

    Willems, C.M.E.

    2011-01-01

    Moving objects are captured in multivariate trajectories, often large data with multiple attributes. We focus on vessel traffic as a source of such data. Patterns appearing from visually analyzing attributes are used to explain why certain movements have occurred. In this research, we have developed

  12. GOLD PRESSURE VESSEL SEAL

    Science.gov (United States)

    Smith, A.E.

    1963-11-26

    An improved seal between the piston and die member of a piston-cylinder type pressure vessel is presented. A layer of gold, of sufficient thickness to provide an interference fit between the piston and die member, is plated on the contacting surface of at least one of the members. (AEC)

  13. Reactor vessel stud tensioner

    International Nuclear Information System (INIS)

    Malandra, L.J.; Beer, R.W.; Salton, R.B.; Spiegelman, S.R.; Cognevich, M.L.

    1982-01-01

    A quick-acting stud tensioner, for facilitating the loosening or tightening of a stud nut on a reactor vessel stud, has gripper jaws which when the tensioner is lowered into engagement with the upper end of the stud are moved inwards to grip the upper end and which when the tensioner is lifted move outward to release the upper end. (author)

  14. Synthesis of a gamma irradiation grafted polytetrafluoroethylene (PTFE) based olefinic copolymer; Estudo da sintese de copolimero olefinico a base de politetrafluoroetileno (PTFE) por meio da enxertia induzida por radiacao gama

    Energy Technology Data Exchange (ETDEWEB)

    Ferreto, Helio Fernando Rodrigues

    2006-07-01

    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)

  15. PDX vacuum vessel stress analysis

    International Nuclear Information System (INIS)

    Nikodem, Z.D.

    1975-01-01

    A stress analysis of PDX vacuum vessel is described and the summary of results is presented. The vacuum vessel is treated as a toroidal shell of revolution subjected to an internal vacuum. The critical buckling pressure is calculated. The effects of the geometrical discontinuity at the juncture of toroidal shell head and cylindrical outside wall, and the concavity of the cylindrical wall are examined. An effect of the poloidal field coil supports and the vessel outside supports on the stress distribution in the vacuum vessel is determined. A method evaluating the influence of circular ports in the vessel wall on the stress level in the vessel is outlined

  16. The use of macro and micro proton beams to study the variation in PIXE yield from metal targets insulated with PTFE, glass and nylon

    International Nuclear Information System (INIS)

    Pillay, A.E.

    1999-01-01

    Proton beams of diameters of 3 mm and 3 μm, were used to observe the differences in PIXE yield from pure metal targets encapsulated with PTFE, glass (macor) and nylon. The beam energy was kept constant at 700 keV. Beam currents varied from about 200 pA with the microbeam and between 1-10 nA with the macrobeam. Considerable enhancement was observed mainly with the use of PTFE, up to about a factor of 18 with the macrobeam and 306 with the microbeam. (author)

  17. Use of DSC and DMA Techniques to Help Investigate a Material Anomaly for PTFE Used in Processing a Piston Cup for the Urine Processor Assembly (UPA) on International Space Station (ISS)

    Science.gov (United States)

    Wingard, Doug

    2010-01-01

    Human urine and flush water are eventually converted into drinking water with the Urine Processor Assembly (UPA) aboard the International Space Station (ISS). This conversion is made possible through the Distillation Assembly (DA) of the UPA. One component of the DA is a molded circular piston cup made of virgin polytetrafluoroethylene (PTFE). The piston cup is assembled to a titanium component using eight fasteners and washers. Molded PTFE produced for spare piston cups in the first quarter of 2010 was different in appearance and texture, and softer than material molded for previous cups. For the suspect newer PTFE material, cup fasteners were tightened to only one-half the required torque value, yet the washers embedded almost halfway into the material. The molded PTFE used in the DA piston cup should be Type II, based on AMS 3667D and ASTM D4894 specifications. The properties of molded PTFE are considerably different between Type I and II materials. Engineers working with the DA thought that if Type I PTFE was molded by mistake instead of Type II material, that could have resulted in the anomalous material properties. Typically, the vendor molds flat sheet PTFE from the same material lot used to mold the piston cups, and tensile testing as part of quality control should verify that the PTFE is Type II material. However, for this discrepant lot of material, such tensile data was not available. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) were two of the testing techniques used at the NASA/Marshall Space Flight Center (MSFC) to investigate the anomaly for the PTFE material. Other techniques used on PTFE specimens were: Shore D hardness testing, tensile testing on dog bone specimens and a qualitative estimation of porosity by optical and scanning electron microscopy.

  18. PTFE-based microreactor system for the continuous synthesis of full-visible-spectrum emitting cesium lead halide perovskite nanocrystals

    Directory of Open Access Journals (Sweden)

    Chengxi Zhang

    2017-11-01

    Full Text Available Colloidal perovskite nanocrystals comprised of all inorganic cesium lead halide (CsPbX3, X = Cl, Br, I or a mixture thereof have potential as optical gain materials due to their high luminescence efficiency. In this work, cesium lead halide nanocrystals are continuously synthesized via a microreactor system consisting of poly(tetrafluoroethylene (PTFE capillaries. The synthesized nanocrystals possess excellent optical properties, including a full width at half maximum of 19–35 nm, high fluorescence quantum yield of 47.8–90.55%, and photoluminescence emission in the range of 450–700 nm. For the same precursor concentrations, the photoluminescence emission peak generally increases with increasing reaction temperature, revealing a controllable temperature effect on the photoluminescence characteristics of the synthesized nanocrystals. For quantum dots synthesized with a Br/I ratio of 1:3, a slight blue shift was observed for reaction temperatures greater than 100 °C. This PTFE-based microreactor system provides the unique capability of continuously synthesizing high-quality perovskite nanocrystals that emit over the full visible spectrum with applications ranging from displays and optoelectronic devices.

  19. The effect of addition of PTFE or urea on luminescence response of copper-doped lithium tetraborate

    Science.gov (United States)

    Iskandar, Ferry; Fajri, Annisa; Nuraeni, Nunung; Stavila, Erythrina; Aimon, Akfiny H.; Nuryadin, Bebeh W.

    2018-04-01

    Lithium tetraborate (Li2B4O7) is a promising material for application in personal dosimetry due to its tissue equivalent properties. The addition of copper as a dopant in Li2B4O7 is known to increase the sensitivity for both photoluminescent (PL) and thermoluminescent (TL) emission. Therefore, in this paper, synthesis of Li2B4O7:Cu is reported. The optimum synthesis condition was achieved using the solution-assisted method, followed by calcination at 700 °C for 2 h. The addition of 0.1 wt% Cu resulted in the highest PL and TL emissions. Further investigation of the influence of polytetrafluoroethylene (PTFE) or urea addition on the luminescence response of Li2B4O7:Cu is described. All samples were characterized by x-ray diffraction (XRD), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectrometry, photoluminescence spectrofluorophotometer, thermoluminescence reader, scanning electron microscopy (SEM), and energy dispersive x-ray (EDX) spectroscopy. The addition of PTFE decreased the PL emission of the Li2B4O7:Cu but slightly increased its TL emission. Meanwhile, the addition of urea increased the luminescence emission for both PL and TL of the Li2B4O7:Cu.

  20. Partial ion yield and NEXAFS of 2-(perfluorooctyl)ethanethiol self-assembled monolayer: Comparison with PTFE results

    CERN Document Server

    Setoyama, H; Murase, T; Imamura, M; Mase, K; Okudaira, K K; Hara, M; Ueno, N

    2003-01-01

    Partial-ion-yield (PIY) spectra using ion time-of-flight (TOF) method and near-edge absorption fine structure (NEXAFS) spectra were measured for 2-(perfluorooctyl)ethanethiol [CF sub 3 (CF sub 2) sub 7 (CH sub 2) sub 2 SH] self-assembled monolayer (F8-SAM) on Au(1 1 1) near carbon K-edge. The PIY spectra of the F8-SAM at the magic angle, where -CF sub 3 groups exist at the surface were compared with those of the rubbed polytetrafluoroethylene (PTFE) thin film. The F sup + intensity from the F8-SAM at the photon energy of the sharp peak of the NEXAFS, which originates from the excitation of C1s electron to sigma sup * (C-F) states at -CF sub 2 - chain, was extremely smaller than that from the rubbed PTFE film. This result clearly indicates that the ions observed by PIY do not originate from the film inside but from the surface. This was confirmed by changes in ion-TOF mass spectra during soft X-ray induced etching of the F8-SAM. The NEXAFS peaks of the F8-SAM were also assigned by considering PIY results.

  1. Influence of SiO2 Addition on Properties of PTFE/TiO2 Microwave Composites

    Science.gov (United States)

    Yuan, Ying; Wang, Jie; Yao, Minghao; Tang, Bin; Li, Enzhu; Zhang, Shuren

    2018-01-01

    Composite substrates for microwave circuit applications have been fabricated by filling polytetrafluoroethylene (PTFE) polymer matrix with ceramic powder consisting of rutile TiO2 ( D 50 ≈ 5 μm) partially substituted with fused amorphous SiO2 ( D 50 ≈ 8 μm) with composition x vol.% SiO2 + (50 - x) vol.% TiO2 ( x = 0, 3, 6, 9, 12), and the effects of SiO2 addition on characteristics such as the density, moisture absorption, microwave dielectric properties, and thermal properties systematically investigated. The results show that the filler was well distributed throughout the matrix. High dielectric constant ( ɛ r > 7.19) and extremely low moisture absorption (ceramic particles served as barriers and improved the thermal stability of the PTFE polymer, retarding its decomposition. The temperature coefficient of dielectric constant ( τ ɛ ) of the composites shifted toward the positive direction (from - 309 ppm/°C to - 179 ppm/°C) as the SiO2 content was increased, while the coefficient of thermal expansion remained almost unchanged (˜ 35 ppm/°C).

  2. Tl response of LiF: Mg, Cu, P + PTFE (Mexico) and GR200A (China) dosemeters

    International Nuclear Information System (INIS)

    Gonzalez M, P.R.; Azorin N, J.; Furetta, C.

    2003-01-01

    TLD-100 was the commercial dosemeter more known since some decades ago. This dosemeter was considered for many research groups as the reference material for developing new Tl materials for ionizing radiation dosimetry. Actually it seems that TLD-100 is going to be replaced by the Chinese material GR200A, as reference material due that this material in addition to be considered as a tissue equivalent material, is 30 to 35 times more sensitive that TLD- 100. Results of the study of the Tl response of LiF: Mg, Cu, P + Ptfe developed at ININ-Mexico, comparing them with those of GR200A are presented. These results showed that the sensitivity (s = Tl intensity/weight x dose) to gamma radiation of the LiF: Mg, Cu, P + Ptfe dosimeters was 4.34 meanwhile that of the commercial dosemeter was 3.41. Detection threshold of the dosemeters studied was 2.22 and 0.52 μGy respectively Repeatability after 10 cycles Irradiation-reading-annealing was ±1.39% and ±1.86% respectively. Both types of dosemeters presented a linear response as a function of gamma radiation in the range from 0.02 mGy and 100 Gy. (Author)

  3. Vessels in Transit - Web Tool

    Data.gov (United States)

    Department of Transportation — A web tool that provides real-time information on vessels transiting the Saint Lawrence Seaway. Visitors may sort by order of turn, vessel name, or last location in...

  4. Reactor vessel sealing plug

    International Nuclear Information System (INIS)

    Dooley, R.A.

    1986-01-01

    An apparatus is described for sealing a cold leg nozzle of a nuclear reactor pressure vessel from a remote location comprising: at least one sealing plug for mechanically sealing the nozzle from the inside of the reactor pressure vessel. The sealing plug includes a plate and a cone assembly having an end part receptive in the nozzle, the plate being axially moveable relative to the cone assembly. The plate and cone assembly have confronting bevelled edges defining an opening therebetween. A primary O-ring is disposed about the opening and is supported on the bevelled edges, the plate being guidably mounted to the cone assembly for movement toward the cone assembly to radially expand the primary O-ring into sealing engagement with the nozzle. A means is included for providing relative movement between the outer plate and the cone assembly

  5. Mobile nuclear reactor containment vessel

    International Nuclear Information System (INIS)

    Thompson, R.E.; Spurrier, F.R.; Jones, A.R.

    1978-01-01

    A containment vessel for use in mobile nuclear reactor installations is described. The containment vessel completely surrounds the entire primary system, and is located as close to the reactor primary system components as is possible in order to minimize weight. In addition to being designed to withstand a specified internal pressure, the containment vessel is also designed to maintain integrity as a containment vessel in case of a possible collision accident

  6. Nuclear reactor vessel inspection apparatus

    International Nuclear Information System (INIS)

    Blackstone, E.G.; Lofy, R.A.; Williams, L.P.

    1979-01-01

    Apparatus for the in situ inspection of a nuclear reactor vessel to detect the location and character of flaws in the walls of the vessel, in the welds joining the various sections of the vessel, in the welds joining attachments such as nozzles, elbows and the like to the reactor vessel and in such attachments wherein an inspection head carrying one or more ultrasonic transducers follows predetermined paths in scanning the various reactor sections, welds and attachments

  7. Reactor vessel stud closure system

    International Nuclear Information System (INIS)

    Spiegelman, S.R.; Salton, R.B.; Beer, R.W.; Malandra, L.J.; Cognevich, M.L.

    1982-01-01

    A quick-acting stud tensioner apparatus for enabling the loosening or tightening of a stud nut on a reactor vessel stud. The apparatus is adapted to engage the vessel stud by closing a gripper around an upper end of the vessel stud when the apparatus is seated on the stud. Upon lifting the apparatus, the gripper releases the vessel stud so that the apparatus can be removed

  8. Reactor pressure vessel steels

    International Nuclear Information System (INIS)

    Van De Velde, J.; Fabry, A.; Van Walle, E.; Chaouuadi, R.

    1998-01-01

    Research and development activities related to reactor pressure vessel steels during 1997 are reported. The objectives of activities of the Belgian Nuclear Research Centre SCK/CEN in this domain are: (1) to develop enhanced surveillance concepts by applying micromechanics and fracture-toughness tests to small specimens, and by performing damage modelling and microstructure characterization; (2) to demonstrate a methodology on a broad database; (3) to achieve regulatory acceptance and industrial use

  9. Reactor Pressure Vessel Steels

    Energy Technology Data Exchange (ETDEWEB)

    Van de Velde, J.; Fabry, A.; Van Walle, E.; Chaoudi, R

    1998-07-01

    SCK-CEN's R and D programme on Reactor Pressure Vessel (RPV) Steels in performed in support of the RVP integrity assessment. Its main objectives are: (1) to develop enhanced surveillance concepts by applying micromechanics and fracture-toughness tests to small specimens, and by performing damage modelling and microstructure characterization; (2) to demonstrate the applied methodology on a broad database; (3) to achieve regulatory acceptance and industrial use. Progress and achievements in 1999 are reported.

  10. Different techniques of vessel reconstruction during kidney transplantation

    Directory of Open Access Journals (Sweden)

    Tomić Aleksandar

    2015-01-01

    Full Text Available Background/Aim. Multiple renal arteries (MRAs represent a surgical challenge by the difficulty in performing anastomoses, bleeding and stenosis. MRAs should be preserved and special attention should be paid to accessory polar arteries. All renal arteries (RAs must be reconstructed and prepared for safe anastomosis. The paper decribed the different techniques of vessel reconstruction during kidney transplantation including important steps within recovery of organs, preparation and implantation. Methods. In a 16-year period (1996-2012 of kidney transplantation in the Military Medical Academy, Belgrade, a total of 310 living donors and 44 human cadaver kidney transplantations were performed, of which 28 (8% kidneys had two or more RAs. Results. All the transplanted kidneys had immediate function. We repaired 20 cases of donor kidneys with 2 arteries, 4 cases with three RAs, one case with 4 RAs, one case with 4 RAs and renal vein reconstruction, one case with 3 arteries and additional polytetrafluoroethylene (PTFE graft reconstruction, one case with transected renal artery and reconstruction with 5 cm long deceased donor external iliac artery. There were no major complications and graft failure. At a minimum of 1-year follow-up, all the patients showed normal renal function. Conclusion. Donor kidney transplantation on a contralateral side and “end-to-end” anastomosis of the renal artery to the internal iliac artery (IIA is our standard procedure with satisfactory results. Renal artery reconstruction and anastomosis with IIA is a safe and highly efficient procedure and kidneys with MRAs are not contraindicated for transplantation. A surgical team should be fully competent to remove cadaveric abdominal organs to avoid accidental injuries of organs vessels.

  11. Phenomenological vessel burst investigations

    International Nuclear Information System (INIS)

    Hippelein, K.W.; Julisch, P.; Muz, J.; Schiedermaier, J.

    1985-07-01

    Fourteen burst experiments have been carried out using vessels with circumferential and longitudinal flaws, for investigation of the fracture behaviour, i.e. the time-related fracture opening. The vessels had dimensions (outer diameter x wall thickness = 800 x 47 mm) which correspond to the dimensions of the main coolant piping of a 1300 MW e PWR. The test specimens had been made of the base-safe material 20 MnMoNi 55 and of a special, 22 NiMoCr 37 base alloy. The experimental conditions with regard to pressure and temperature have been chosen so as to correspond to normal operating conditions of a PWR (p∝17.5 MPa, T∝300 0 C), i.e. the flaws have been so dimensioned that failure was to be expected at a pressure of p∝17.5 MPa. As a rule, water has been used as the pressure medium, or in some cases air, in order to influence the time-dependent pressure decrease. Fluid and structural dynamics calculations have also been made. In order to determine the impact of a fast propagating crack on the leak-to-fracture curve, which normally is defined by quasistationary experiments, suitable tests have been made with large-volume, cylindrical vessels (outer diameter x wall thickness x length = 3000 x 21 x 14000 mm) made of the material WSt E 43. The leak-before-fracture criterion has been confirmed. (orig./HP) [de

  12. Blood Vessels in Allotransplantation.

    Science.gov (United States)

    Abrahimi, P; Liu, R; Pober, J S

    2015-07-01

    Human vascularized allografts are perfused through blood vessels composed of cells (endothelium, pericytes, and smooth muscle cells) that remain largely of graft origin and are thus subject to host alloimmune responses. Graft vessels must be healthy to maintain homeostatic functions including control of perfusion, maintenance of permselectivity, prevention of thrombosis, and participation in immune surveillance. Vascular cell injury can cause dysfunction that interferes with these processes. Graft vascular cells can be activated by mediators of innate and adaptive immunity to participate in graft inflammation contributing to both ischemia/reperfusion injury and allograft rejection. Different forms of rejection may affect graft vessels in different ways, ranging from thrombosis and neutrophilic inflammation in hyperacute rejection, to endothelialitis/intimal arteritis and fibrinoid necrosis in acute cell-mediated or antibody-mediated rejection, respectively, and to diffuse luminal stenosis in chronic rejection. While some current therapies targeting the host immune system do affect graft vascular cells, direct targeting of the graft vasculature may create new opportunities for preventing allograft injury and loss. © Copyright 2015 The American Society of Transplantation and the American Society of Transplant Surgeons.

  13. Ionizing radiations and blood vessels

    International Nuclear Information System (INIS)

    Vorob'ev, E.I.; Stepanov, R.P.

    1985-01-01

    Data on phenomenology of radiation-induced changes in blood vessels are systematized and authors' experience is generalized. Modern concepts about processes leading to vessel structure injury after irradiation is critically analyzed. Special attention is paid to reparation and compensation of X-ray vessel injury, consideration of which is not yet sufficiently elucidated in literature

  14. Ionizing radiations and blood vessels

    International Nuclear Information System (INIS)

    Vorob'ev, E.I.; Stepanov, R.P.

    1985-01-01

    Data on phenomeology of radiation changes of blood vessels are systemized and the authors' experience is generalyzed. A critical analysis of modern conceptions on processes resulting in vessel structure damage after irradiation, is given. Special attention is paid to reparation and compensation of radiation injury of vessels

  15. Determination of kinetic parameters in Tl dosemeters of LiF: Mg, Cu, P + PTFE developed in the ININ; Determinacion de parametros cineticos en dosimetros Tl de LiF: Mg, Cu, P + PTFE desarrollados en el ININ

    Energy Technology Data Exchange (ETDEWEB)

    Basurto G, B.S

    2002-07-01

    The objective of this work, is the one of determining the kinetic parameters of the dosemeter of LiF: Mg, Cu, P + Ptfe; starting from the curves Tl obtained at being irradiated with alpha radiation ({alpha}), beta ({beta}) and gamma ({gamma}). As like to compare its sensitivity with each radiation type, considering the sensitivity of the TLD-100 as the unit. In the Chapter 1, the fundamental structure of the matter is described, making emphasis in the different radiation types, and their interaction with this. In the Chapter 2, the units are described but used in the dosimetry of the radiation. In the Chapter 3, the basic concepts of the phenomenon of Tl are described and those are explained characteristic of the deconvolution method to determine the kinetics of the one phenomenon. In the Chapter 4, the methodology is detailed that was used in the elaboration of this thesis work, describing the material Tl that were considered like reference, as well as the sources of ionizing radiation, with those that the dosemeters were irradiated and the equipment in the one that the curves Tl was obtained. Reference is made to the software used to carry out the deconvolution of the curves Tl that were obtained in the one experimental development. In the Chapter 5, the obtained results of this study are presented, showing the tables of homogenization of dosemeters and the reading of the same one; they are observed the curves Tl obtained to different radiation doses (alpha, beta and gamma), the intensity Tl in function of the dose. Also they are tabulated, the obtained results in the kinetic parameters of the three different study materials (TLD-100H, USA; TLD-100, USA and LiF: Mg, Cu, P + Ptfe developed in the l.N.l.N). They are analyzed shortly for each material Tl their sensitivity to the ionizing radiation as well as their kinetic parameters. The obtained results showed that the Tl dosemeters of LiF: Mg,Cu,P + Ptfe, they presented a bigger sensitivity that the TLD-100 when

  16. Tribological Behavior of TiC/a-C : H-Coated and Uncoated Steels Sliding Against Phenol-Formaldehyde Composite Reinforced with PTFE and Glass Fibers

    NARCIS (Netherlands)

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

    2013-01-01

    Tribological experiments on phenol-formaldehyde composite reinforced with polytetrafluoroethylene (PTFE) and glass fibers were performed against 100Cr6 steel and TiC/a-C:H thin film-coated 100Cr6 steel. In both cases, the coefficient of friction increases with increasing sliding distance until a

  17. Design and fabrication of a PET/PTFE-based piezoelectric squeeze mode drop-on-demand inkjet printhead with interchangeable nozzle

    KAUST Repository

    Li, Erqiang; Xu, Qian; Sun, Jie; Fuh, Jerry; Wong, Yokesan; Thoroddsen, Sigurdur T

    2010-01-01

    , or Teflon) tubing, which of a much softer material, than the conventionally used glass tubing. Applying the same electrical voltage, PET/PTFE-based printhead will generate a larger volume change in the material to be dispensed. The novel printhead fabricated

  18. The effect on patency of type, shape and volume of a vein collar used at the distal anastomis of PTFE-bypass to arteries below-knee

    DEFF Research Database (Denmark)

    Lundgren, F; Schroeder, Torben Veith

    2012-01-01

    The aim of this paper was to study the effect on patency rate of different types of vein collar (Miller's original or St Mary's boot), different length/height shapes of vein collar, and different vein collar volumes at the distal anastomosis of PTFE-bypass grafts to below-knee arteries in patients...

  19. Design and fabrication of a PET/PTFE-based piezoelectric squeeze mode drop-on-demand inkjet printhead with interchangeable nozzle

    KAUST Repository

    Li, Erqiang

    2010-09-01

    A PET/PTFE-based piezoelectric squeeze mode drop-on-demand inkjet printhead with interchangeable nozzles is designed and fabricated. The printhead chamber is comprised of PET (polyethylene terephthalate) tubing or PTFE (polytetrafluoroethylene, or Teflon) tubing, which of a much softer material, than the conventionally used glass tubing. Applying the same electrical voltage, PET/PTFE-based printhead will generate a larger volume change in the material to be dispensed. The novel printhead fabricated herein has successfully dispensed liquids with viscosities up to 100 cps, as compared to 20 cps for the commercial printheads. Furthermore, PTFE-based printhead provides excellent anti-corrosive property when strongly corrosive inks are involved. The interchangeable nozzle design enables the same printhead to be fitted with nozzles of different orifice size, thus a clogged nozzle can be easily removed for cleaning or replacement. The characteristics of this novel printhead are also studied by dispensing glycerin-water solutions. © 2010 Elsevier B.V. All rights reserved.

  20. Open vessel microwave digestion of food matrices (T6)

    International Nuclear Information System (INIS)

    Rhodes, L.; LeBlanc, G.

    2002-01-01

    Full text: Advancements in the field of open vessel microwave digestion continue to provide solutions for industries requiring acid digestion of large sample sizes. Those interesting in digesting food matrices are particularly interested in working with large amounts of sample and then diluting small final volumes. This paper will show the advantages of instantaneous regent addition and post-digestion evaporation when performing an open vessel digestion and evaporation methods for various food matrices will be presented along with analyte recovery data. (author)

  1. Comparison of the performance of natural latex membranes prepared with different procedures and PTFE membrane in guided bone regeneration (GBR) in rabbits.

    Science.gov (United States)

    Moura, Jonas M L; Ferreira, Juliana F; Marques, Leonardo; Holgado, Leandro; Graeff, Carlos F O; Kinoshita, Angela

    2014-09-01

    This work assessed the performance of membranes made of natural latex extracted from Hevea brasiliensis prepared with three different methods: polymerized immediately after collection without the use of ammonia (L1); polymerized after preservation in ammonia solution (L2); and polymerized after storage in ammonia, followed by Soxhlet technique for the extraction of substances (L3). Polytetrafluoroethylene (PTFE) membrane was used as control. Two 10-mm diameter bone defects were surgically made in the calvaria of thirty adult male New Zealand rabbits. Defects (total n = 60) were treated with guided bone regeneration (GBR) using L1, L2, L3 or PTFE membranes (n = 15 for each membrane). Ten animals were euthanized after 7, 20 and 60 days postoperatively so that five samples (n = 5) of each treatment were collected at each time, and bone regeneration was assessed microscopically. The microscopic analysis revealed defects filled with blood clot and new bone formation at the margins of the defect in all 7-day samples, while 20-day defects were mainly filled with fibrous connective tissue. After 60 days defects covered with L1 membranes showed a significantly larger bone formation area in comparison to the other groups (P PTFE membranes was also investigated in six additional rabbits. The animals were subjected to the same surgical procedure for the confection of one 10-mm diameter bone defect that was treated with L1 (n = 3) or PTFE (n = 3). Fifty-three days later, a second surgery was performed to make a second defect, which was treated with the same type of membrane used in the first surgery. Seven days later, the animals were euthanized and samples analyzed. No differences among L1 and PTFE samples collected from sensitized and non-sensitized animals were found (P > 0.05, Kruskal-Wallis). Therefore, the results demonstrated that latex membranes presented performance comparable to PTFE membranes, and that L1 membranes induced higher bone formation. L1 and

  2. Determination of kinetic parameters in Tl dosemeters of LiF: Mg, Cu, P + PTFE developed in the ININ

    International Nuclear Information System (INIS)

    Basurto G, B.S.

    2002-01-01

    The objective of this work, is the one of determining the kinetic parameters of the dosemeter of LiF: Mg, Cu, P + Ptfe; starting from the curves Tl obtained at being irradiated with alpha radiation (α), beta (β) and gamma (γ). As like to compare its sensitivity with each radiation type, considering the sensitivity of the TLD-100 as the unit. In the Chapter 1, the fundamental structure of the matter is described, making emphasis in the different radiation types, and their interaction with this. In the Chapter 2, the units are described but used in the dosimetry of the radiation. In the Chapter 3, the basic concepts of the phenomenon of Tl are described and those are explained characteristic of the deconvolution method to determine the kinetics of the one phenomenon. In the Chapter 4, the methodology is detailed that was used in the elaboration of this thesis work, describing the material Tl that were considered like reference, as well as the sources of ionizing radiation, with those that the dosemeters were irradiated and the equipment in the one that the curves Tl was obtained. Reference is made to the software used to carry out the deconvolution of the curves Tl that were obtained in the one experimental development. In the Chapter 5, the obtained results of this study are presented, showing the tables of homogenization of dosemeters and the reading of the same one; they are observed the curves Tl obtained to different radiation doses (alpha, beta and gamma), the intensity Tl in function of the dose. Also they are tabulated, the obtained results in the kinetic parameters of the three different study materials (TLD-100H, USA; TLD-100, USA and LiF: Mg, Cu, P + Ptfe developed in the l.N.l.N). They are analyzed shortly for each material Tl their sensitivity to the ionizing radiation as well as their kinetic parameters. The obtained results showed that the Tl dosemeters of LiF: Mg,Cu,P + Ptfe, they presented a bigger sensitivity that the TLD-100 when being

  3. Optimization of the obtaining method of CaSO{sub 4}: Dy + Ptfe dosimeters; Optimizacion del metodo de obtencion de dosimetros de CaSO{sub 4}: Dy + PTFE

    Energy Technology Data Exchange (ETDEWEB)

    Galicia A, J.; Rioja Ch, J.; Torijano C, E.; Azorin N, J., E-mail: blink19871@hotmail.com [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, 09340 Mexico D. F. (Mexico)

    2012-10-15

    This work contain the obtained results of studying the response when irradiating to different dose of X-rays, dosimeters of CaSO{sub 4}: Dy + Ptfe using different lapses of time in their preparation (a lot of selected dosimeters of an elaboration process of 3 days and another of an elaboration process of 2 hours). For the elaboration of the powdered material, the evaporation method was used; the irradiation were carried out in a lineal accelerator Elekta Synergy property of the National Medical Center, 20 de November. The similarities and differences are shown among the two dosimeters lots together with an analysis of the shine curves and of calibration selecting those that presented a better behaviour and a more rea liable response. (Author)

  4. Pressure vessel lid

    International Nuclear Information System (INIS)

    Schoening, J.; Elter, C.; Becker, G.; Pertiller, S.

    1986-01-01

    The invention concerns a lid for closing openings in reactor pressure vessels containing helium, which is made as a circular casting with hollow spaces and a flat floor and is set on the opening and kept down. It consists of helium-tight metal cast material with sufficient temperature resistance. There are at least two concentric heat resistant seals let into the bottom of the lid. The bottom is in immediate contact with the container atmosphere and has hollow spaces in its inside in the area opposite to the opening. (orig./HP) [de

  5. [Small vessel cerebrovascular disease].

    Science.gov (United States)

    Cardona Portela, P; Escrig Avellaneda, A

    2018-05-09

    Small vessel vascular disease is a spectrum of different conditions that includes lacunar infarction, alteration of deep white matter, or microbleeds. Hypertension is the main risk factor, although the atherothrombotic lesion may be present, particularly in large-sized lacunar infarctions along with other vascular risk factors. MRI findings are characteristic and the lesions authentic biomarkers that allow differentiating the value of risk factors and defining their prognostic value. Copyright © 2018 SEH-LELHA. Publicado por Elsevier España, S.L.U. All rights reserved.

  6. Preparation of thermoluminescent dosimeters of LiF: Mg, Cu, P + Ptfe for environmental radiological monitoring and radiodiagnosis; Preparacion de dosimetros termoluminiscentes de LiF: Mg, Cu, P + PTFE para monitoreo radiologico ambiental y radiodiagnostico

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez L, A

    1997-12-31

    The necessity of finding a thermoluminescent material for measuring gamma and X radiation in applications like environmental monitoring, personnel dosimetry and biomedical sciences (radiotherapy and radiodiagnosis), but with special characteristics such as low umbral detection, independence of the energy of radiation and equivalency with the tissue. This made us think in lithium fluoride activated with magnesium, copper and phosphorous (LiF: Mg, Cu, P). In this thesis I developed this material chips like shape embedded in polytetrafluoroethylene (LiF: Mg, Cu, P+Ptfe). The chapter 1 and 2 talk about the atom is conformed and the interaction of the radiation with the matter. The requirements of Tl material, types of dosimetry system, biological effects and units of measurements are discussed in chapter 3 as well as the recommended limits of the International Commission on Radiological Protection ICRP. Chapter 4 shows aspects of the thermoluminescence phenomenon and describes, at the same time, the determination of the most important thermoluminescent parameters (kinetic order, energy or trap depth and the frequency factor). Chapter 5 describes the major characteristics and properties of Tl materials and its requirements for dosimetric use. Chapter 6 deals with the preparations of LiF: Mg, Cu, P+Ptfe chips and some tests for improving its sensitivity, describes the dosimetric tests and requirements proposed by American National Standard Institute ANSI-N545 Like: umbral of detection, homogeneity, fading, repeatability, linearity, effects of UV and fluorescent light etc. Finally in chapter 7 I do a report about analysis of results, conclusions and some recommendations. (Author).

  7. PTFE Graft as a "Bridge" to Communicating Veins Maturation in the Treatment of an Intrahepatic Cholangiocarcinoma Involving the 3 Hepatic Veins. The Minor-but-Complex Liver Resection.

    Science.gov (United States)

    Urbani, Lucio; Balestri, Riccardo; Sidoti, Francesco; Bernardini, Juri Riccardo; Arces, Francesco; Licitra, Gabriella; Leoni, Chiara; Forfori, Francesco; Colombatto, Piero; Boraschi, Piero; Castagna, Maura; Buccianti, Piero

    2016-12-01

    Parenchyma-sparing liver surgery allows resecting hepatic veins (HV) at the hepatocaval confluence with minor (PTFE graft can be used as a bridge to communicating-veins maturation to ensure the correct outflow of the spared liver. We present a video of an intrahepatic cholangiocarcinoma (IC) involving the three HV at the hepatocaval confluence treated with this approach. In a 50-year old obese (BMI 44.8) male a 6-cm IC involving the hepatocaval confluence was identified during the follow-up for a kidney malignancy. At the preoperative CT scan the left HV was not detectable, the middle HV was incorporated within the tumor, and right HV had a 3-cm contact with the tumor. No communicating veins were evident at preoperative imaging. After a J-shape thoracophrenolaparotomy, the resection of segments II-III-IVa was partially extended to segment VIII-VII and I. The right HV was detached from the tumor, and the middle HV was reconstructed with a 7-mm ringed-armed PTFE graft anastomosed to V8. Surgery lasted 20 h and 55 min with an estimated blood loss of 3500 ml, but the postoperative course was uneventful and the patient was discharged on the 14th postoperative day. One month later the CT scan showed a patent PTFE graft with the maturation of communicating-veins. One year later a complete thrombosis of the PTFE graft was observed with normal liver perfusion and function, and the patient was disease-free. PTFE-based parenchyma-sparing liver resection is a new tool to treat tumors located at the hepatocaval confluence exploiting the maturation of intrahepatic communicating-veins between main HV.

  8. Environmental transmission electron microscopy investigations of Pt-Fe2O3 nanoparticles for nucleating carbon nanotubes

    DEFF Research Database (Denmark)

    He, Maoshuai; Jin, Hua; Zhang, Lili

    2016-01-01

    electron microscopy, restructuring of the acorn-like Pt-Fe2O3 nanoparticles at reaction conditions is investigated. Upon heating to reaction temperature, ε-Fe2O3 is converted to β-Fe2O3, which can be subsequently reduced to metallic Fe once introducing CO. As Pt promotes the carburization of Fe, part...... of the metallic Fe reacts with active carbon atoms to form Fe2.5C instead of Fe3C, catalyzing the nucleation of carbon nanotubes. Nanobeam electron diffraction characterizations on SWCNTs grown under ambient pressure at 800 °C demonstrate that their chiral angle and diameter distributions are similar to those...

  9. Alveolar Ridge Preservation with nc-HA and d-PTFE Membrane: A Clinical, Histologic, and Histomorphometric Study.

    Science.gov (United States)

    Laurito, Domenica; Lollobrigida, Marco; Gianno, Francesca; Bosco, Sandro; Lamazza, Luca; De Biase, Alberto

    Alveolar ridge preservation has become a very common procedure following tooth extraction. This study presents a clinical, histologic, and histomorphometric analysis of postextraction bone changes using nanocrystalline hydroxyapatite (nc-HA) and exposed high-density polytetrafluoroethylene (d-PTFE) membrane. A total of 10 extraction sockets were treated. Clinical measurements were taken after tooth extraction with a customized acrylic stent to ensure the same measurement points. At 6 months, clinical measurements were repeated and bone specimens taken. An overall bone reduction was observed. The histologic and histomorphometric analysis revealed newly formed bone (25.92% ± 18.78%), soft tissue (28.55% ± 9.73%), and residual graft particles (15.43% ± 11.08%). Further studies are necessary to evaluate the efficacy of this technique over the long term.

  10. Tl response of KMgF3 :Lu+PTFE depending on the dose of gamma radiation of 60Co

    International Nuclear Information System (INIS)

    Lopez, A.; Gonzalez, P.R.; Furetta, C.; Azorin, J; Rivera, T.; Sepulveda, F.

    2002-01-01

    Due to the great interest in Tl dosimetry for measuring the levels of radiation doses, as environmental as in the different medical radiation applications in different laboratories of the World it is continued in the searching of new Tl materials with optimum dosimetric characteristics and low cost. In this work the obtained results when irradiating Tl dosemeters of KMgF 3 :Lu + PTFE with gamma radiation of 60 Co are presented. Such results showed that this material presents linearity of response depending on the dose between 0.016 to 100 Gy. Although it is continued with the characterization tests it is able to say that this Tl new material can be used for dosimetric aims. (Author)

  11. An automated vessel segmentation of retinal images using multiscale vesselness

    International Nuclear Information System (INIS)

    Ben Abdallah, M.; Malek, J.; Tourki, R.; Krissian, K.

    2011-01-01

    The ocular fundus image can provide information on pathological changes caused by local ocular diseases and early signs of certain systemic diseases, such as diabetes and hypertension. Automated analysis and interpretation of fundus images has become a necessary and important diagnostic procedure in ophthalmology. The extraction of blood vessels from retinal images is an important and challenging task in medical analysis and diagnosis. In this paper, we introduce an implementation of the anisotropic diffusion which allows reducing the noise and better preserving small structures like vessels in 2D images. A vessel detection filter, based on a multi-scale vesselness function, is then applied to enhance vascular structures.

  12. Preparation of thermoluminescent dosimeters of LiF: Mg, Cu, P + Ptfe for environmental radiological monitoring and radiodiagnosis

    International Nuclear Information System (INIS)

    Ramirez L, A.

    1996-01-01

    The necessity of finding a thermoluminescent material for measuring gamma and X radiation in applications like environmental monitoring, personnel dosimetry and biomedical sciences (radiotherapy and radiodiagnosis), but with special characteristics such as low umbral detection, independence of the energy of radiation and equivalency with the tissue. This made us think in lithium fluoride activated with magnesium, copper and phosphorous (LiF: Mg, Cu, P). In this thesis I developed this material chips like shape embedded in polytetrafluoroethylene (LiF: Mg, Cu, P+Ptfe). The chapter 1 and 2 talk about the atom is conformed and the interaction of the radiation with the matter. The requirements of Tl material, types of dosimetry system, biological effects and units of measurements are discussed in chapter 3 as well as the recommended limits of the International Commission on Radiological Protection ICRP. Chapter 4 shows aspects of the thermoluminescence phenomenon and describes, at the same time, the determination of the most important thermoluminescent parameters (kinetic order, energy or trap depth and the frequency factor). Chapter 5 describes the major characteristics and properties of Tl materials and its requirements for dosimetric use. Chapter 6 deals with the preparations of LiF: Mg, Cu, P+Ptfe chips and some tests for improving its sensitivity, describes the dosimetric tests and requirements proposed by American National Standard Institute ANSI-N545 Like: umbral of detection, homogeneity, fading, repeatability, linearity, effects of UV and fluorescent light etc. Finally in chapter 7 I do a report about analysis of results, conclusions and some recommendations. (Author)

  13. Role of arginase in vessel wall remodeling

    Directory of Open Access Journals (Sweden)

    William eDurante

    2013-05-01

    Full Text Available Arginase metabolizes the semi-essential amino acid L-arginine to L-ornithine and urea. There are two distinct isoforms of arginase, arginase I and II, which are encoded by separate genes and display differences in tissue distribution, subcellular localization, and molecular regulation. Blood vessels express both arginase I and II but their distribution appears to be cell-, vessel-, and species-specific. Both isoforms of arginase are induced by numerous pathologic stimuli and contribute to vascular cell dysfunction and vessel wall remodeling in several diseases. Clinical and experimental studies have documented increases in the expression and/or activity of arginase I or II in blood vessels following arterial injury and in pulmonary and arterial hypertension, aging, and atherosclerosis. Significantly, pharmacological inhibition or genetic ablation of arginase in animals ameliorates abnormalities in vascular cells and normalizes blood vessel architecture and function in all of these pathological states. The detrimental effect of arginase in vascular remodeling is attributable to its ability to stimulate vascular smooth muscle cell and endothelial cell proliferation, and collagen deposition by promoting the synthesis of polyamines and L-proline, respectively. In addition, arginase adversely impacts arterial remodeling by directing macrophages towards an inflammatory phenotype. Moreover, the proliferative, fibrotic, and inflammatory actions of arginase in the vasculature are further amplified by its capacity to inhibit nitric oxide synthesis by competing with nitric oxide synthase for substrate, L-arginine. Pharmacologic or molecular approaches targeting specific isoforms of arginase represent a promising strategy in treating obstructive fibroproliferative vascular disease.

  14. PUMP DESIGN AND COMPUTATIONAL FLUID DYNAMIC ANALYSIS FOR HIGH TEMPERATURE SULFURIC ACID TRANSFER SYSTEM

    Directory of Open Access Journals (Sweden)

    JUNG-SIK CHOI

    2014-06-01

    Full Text Available In this study, we proposed a newly designed sulfuric acid transfer system for the sulfur-iodine (SI thermochemical cycle. The proposed sulfuric acid transfer system was evaluated using a computational fluid dynamics (CFD analysis for investigating thermodynamic/hydrodynamic characteristics and material properties. This analysis was conducted to obtain reliable continuous operation parameters; in particular, a thermal analysis was performed on the bellows box and bellows at amplitudes and various frequencies (0.1, 0.5, and 1.0 Hz. However, the high temperatures and strongly corrosive operating conditions of the current sulfuric acid system present challenges with respect to the structural materials of the transfer system. To resolve this issue, we designed a novel transfer system using polytetrafluoroethylene (PTFE, Teflon® as a bellows material for the transfer of sulfuric acid. We also carried out a CFD analysis of the design. The CFD results indicated that the maximum applicable temperature of PTFE is about 533 K (260 °C, even though its melting point is around 600 K. This result implies that the PTFE is a potential material for the sulfuric acid transfer system. The CFD simulations also confirmed that the sulfuric acid transfer system was designed properly for this particular investigation.

  15. Targeting Therapy Resistant Tumor Vessels

    Science.gov (United States)

    2008-08-01

    Morris LS. Hysterectomy vs. resectoscopic endometrial ablation for the control of abnormal uterine bleeding . A cost-comparative study. J Reprod Med 1994;39...after the antibody treatment contain a pericyte coat, vessel architecture is normal, the diameter of the vessels is smaller (dilated, abnormal vessels...involvement of proteases from inflammatory mast cells and functionally abnormal (Carmeliet and Jain, 2000; Pasqualini (Coussens et al., 1999) and other bone

  16. The vessel fluence; Fluence cuve

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    This book presents the proceedings of the technical meeting on the reactors vessels fluence. They are grouped in eight sessions: the industrial context and the stakes of the vessels control; the organization and the methodology for the fluence computation; the concerned physical properties; the reference computation methods; the fluence monitoring in an industrial context; vessels monitoring under irradiation; others methods in the world; the research and development programs. (A.L.B.)

  17. Americium behaviour in plastic vessels

    International Nuclear Information System (INIS)

    Legarda, F.; Herranz, M.; Idoeta, R.; Abelairas, A.

    2010-01-01

    The adsorption of 241 Am dissolved in water in different plastic storage vessels was determined. Three different plastics were investigated with natural and distilled waters and the retention of 241 Am by these plastics was studied. The same was done by varying vessel agitation time, vessel agitation speed, surface/volume ratio of water in the vessels and water pH. Adsorptions were measured to be between 0% and 70%. The adsorption of 241 Am is minimized with no water agitation, with PET or PVC plastics, and by water acidification.

  18. Americium behaviour in plastic vessels

    Energy Technology Data Exchange (ETDEWEB)

    Legarda, F.; Herranz, M. [Departamento de Ingenieria Nuclear y Mecanica de Fluidos, Escuela Tecnica Superior de Ingenieria de Bilbao, Universidad del Pais Vasco (UPV/EHU), Alameda de Urquijo s/n, 48013 Bilbao (Spain); Idoeta, R., E-mail: raquel.idoeta@ehu.e [Departamento de Ingenieria Nuclear y Mecanica de Fluidos, Escuela Tecnica Superior de Ingenieria de Bilbao, Universidad del Pais Vasco (UPV/EHU), Alameda de Urquijo s/n, 48013 Bilbao (Spain); Abelairas, A. [Departamento de Ingenieria Nuclear y Mecanica de Fluidos, Escuela Tecnica Superior de Ingenieria de Bilbao, Universidad del Pais Vasco (UPV/EHU), Alameda de Urquijo s/n, 48013 Bilbao (Spain)

    2010-07-15

    The adsorption of {sup 241}Am dissolved in water in different plastic storage vessels was determined. Three different plastics were investigated with natural and distilled waters and the retention of {sup 241}Am by these plastics was studied. The same was done by varying vessel agitation time, vessel agitation speed, surface/volume ratio of water in the vessels and water pH. Adsorptions were measured to be between 0% and 70%. The adsorption of {sup 241}Am is minimized with no water agitation, with PET or PVC plastics, and by water acidification.

  19. Americium behaviour in plastic vessels.

    Science.gov (United States)

    Legarda, F; Herranz, M; Idoeta, R; Abelairas, A

    2010-01-01

    The adsorption of (241)Am dissolved in water in different plastic storage vessels was determined. Three different plastics were investigated with natural and distilled waters and the retention of (241)Am by these plastics was studied. The same was done by varying vessel agitation time, vessel agitation speed, surface/volume ratio of water in the vessels and water pH. Adsorptions were measured to be between 0% and 70%. The adsorption of (241)Am is minimized with no water agitation, with PET or PVC plastics, and by water acidification. Copyright 2009 Elsevier Ltd. All rights reserved.

  20. [Large vessel vasculitides].

    Science.gov (United States)

    Morović-Vergles, Jadranka; Puksić, Silva; Gracanin, Ana Gudelj

    2013-01-01

    Large vessel vasculitis includes Giant cell arteritis and Takayasu arteritis. Giant cell arteritis is the most common form of vasculitis affect patients aged 50 years or over. The diagnosis should be considered in older patients who present with new onset of headache, visual disturbance, polymyalgia rheumatica and/or fever unknown cause. Glucocorticoides remain the cornerstone of therapy. Takayasu arteritis is a chronic panarteritis of the aorta ant its major branches presenting commonly in young ages. Although all large arteries can be affected, the aorta, subclavian and carotid arteries are most commonly involved. The most common symptoms included upper extremity claudication, hypertension, pain over the carotid arteries (carotidynia), dizziness and visual disturbances. Early diagnosis and treatment has improved the outcome in patients with TA.

  1. Reactor pressure vessel embrittlement

    International Nuclear Information System (INIS)

    1992-07-01

    Within the framework of the IAEA extrabudgetary programme on the Safety of WWER-440/230 NPPs, a list of safety issues requiring broad studies of generic interest have been agreed upon by an Advisory Group who met in Vienna in September 1990. The list was later revised in the light of the programme findings. The information on the status of the issues, and on the amount of work already completed and under way in the various countries, needs to be compiled. Moreover, an evaluation of what further work is required to resolve each one of the issues is also necessary. In view of this, the IAEA has started the preparation of a series of status reports on the various issues. This report on the generic safety issue ''Reactor Pressure Vessel Embrittlement'' presents a comprehensive survey of technical information available in the field and identifies those aspects which require further investigation. 39 refs, 21 figs, 4 tabs

  2. Reactor containment vessel

    International Nuclear Information System (INIS)

    Ochiai, Kanehiro; Hayagumo, Sunao; Morikawa, Matsuo.

    1981-01-01

    Purpose: To safety and simplify the structure in a reactor containment vessel. Constitution: Steam flow channels with steam jetting ports communicating to coolants are provided between a communication channel and coolants in a pressure suppression chamber. Upon loss of coolant accidents, pressure in a dry well will increase, then force downwards water in an annulus portion and further flow out the water through steam jetting ports into a suppression pool. Thus, the steam flow channel is filled with steams or airs present in the dry well, which are released through the steam jetting ports into the pressure suppression chamber. Even though water is violently vibrated owing to the upward movement of air bubbles and condensation of steam bubbles, the annular portion and the steam jetting ports are filled with steams or the like, direct dynamic loads onto the structures such as communication channels can be avoided. (J.P.N.)

  3. Pressure vessel for nuclear reactors

    International Nuclear Information System (INIS)

    1975-01-01

    The invention applies to a pressure vessel for nuclear reactors whose shell, made of cast metal segments, has a steel liner. This liner must be constructed to withstand all operational stresses and to be easily repairable. The invention solves this problem by installing the liner at a certain distance from the inner wall of the pressure vessel shell and by filling this clearance with supporting concrete. Both the concrete and the steel liner must have a lower prestress than the pressure vessel shell. In order to avoid damage to the liner when prestressing the pressure vessel shell, special connecting elements are provided which consist of welded-on fastening elements projecting into recesses in the cast metal segments of the pressure vessel. Their design is described in detail. (TK) [de

  4. Comparison of TEVAR resin beads, PAN fibers, and ePTFE membranes as a solid support for Aliquat-336 in immobilized liquid extraction chromatography for separation of actinides

    International Nuclear Information System (INIS)

    Joe Dauner; Steve Workman

    2012-01-01

    The following paper covers a comparison of two new systems to traditional TEVA R resin systems for the analytical separation of actinides by immobilized liquid-liquid extraction using Aliquat-336. The new systems are using expanded polytetrafluroethane (ePTFE) membrane or polyacrylonitrile (PAN) fibers as the solid support. The systems are compared in two ways. First in how much Aliquat-336 they contain with the Vs, ratio of volume of Aliquat-336 to volume of polymeric support, being 0.158, 0.483, and 0.590 for the TEVA R resin, PAN fibers, and the ePTFE systems, respectively. The second comparison is in their performance capacity of extraction of uranyl chloride anion complex. The fiber and resins systems show similar capacities, and the membrane system being an order of magnitude less than the other systems. A cost comparison demonstrates the savings advantages of using a fiber based support compared with resin and membrane support systems. (author)

  5. Containment vessel stability analysis

    International Nuclear Information System (INIS)

    Harstead, G.A.; Morris, N.F.; Unsal, A.I.

    1983-01-01

    The stability analysis for a steel containment shell is presented herein. The containment is a freestanding shell consisting of a vertical cylinder with a hemispherical dome. It is stiffened by large ring stiffeners and relatively small longitudinal stiffeners. The containment vessel is subjected to both static and dynamic loads which can cause buckling. These loads must be combined prior to their use in a stability analysis. The buckling loads were computed with the aid of the ASME Code case N-284 used in conjunction with general purpose computer codes and in-house programs. The equations contained in the Code case were used to compute the knockdown factors due to shell imperfections. After these knockdown factors were applied to the critical stress states determined by freezing the maximum dynamic stresses and combining them with other static stresses, a linear bifurcation analysis was carried out with the aid of the BOSOR4 program. Since the containment shell contained large penetrations, the Code case had to be supplemented by a local buckling analysis of the shell area surrounding the largest penetration. This analysis was carried out with the aid of the NASTRAN program. Although the factor of safety against buckling obtained in this analysis was satisfactory, it is claimed that the use of the Code case knockdown factors are unduly conservative when applied to the analysis of buckling around penetrations. (orig.)

  6. Pressure vessel design

    International Nuclear Information System (INIS)

    Annaratone, D.

    2007-01-01

    This book guides through general and fundamental problems of pressure vessel design. It moreover considers problems which seem to be of lower importance but which turn out to be crucial in the design phase. The basic approach is rigorously scientific with a complete theoretical development of the topics treated, but the analysis is always pushed so far as to offer concrete and precise calculation criteria that can be immediately applied to actual designs. This is accomplished through appropriate algorithms that lead to final equations or to characteristic parameters defined through mathematical equations. The first chapter describes how to achieve verification criteria, the second analyzes a few general problems, such as stresses of the membrane in revolution solids and edge effects. The third chapter deals with cylinders under pressure from the inside, while the fourth focuses on cylinders under pressure from the outside. The fifth chapter covers spheres, and the sixth is about all types of heads. Chapter seven discusses different components of particular shape as well as pipes, with special attention to flanges. The eighth chapter discusses the influence of holes, while the ninth is devoted to the influence of supports. Finally, chapter ten illustrates the fundamental criteria regarding fatigue analysis. Besides the unique approach to the entire work, original contributions can be found in most chapters, thanks to the author's numerous publications on the topic and to studies performed ad hoc for this book. (orig.)

  7. Wound Healing and ndash; A Proteomic Analysis of the Effect of Erythropoietin on Granulation Tissue Isolated from ePTFE Implants

    Directory of Open Access Journals (Sweden)

    Bekka Christensen

    2014-02-01

    Conclusion: Daily injection of recombinant human erythropoietin of 1000 IU/kg alters the protein expression of GAPDH, ENOA and TPIS in granulation tissue from wounds on postoperative day 9. The successful combination of proteomic analysis of wound tissue and the ePTFE wound model could advance our knowledge of the complex healing process. [Arch Clin Exp Surg 2014; 3(1.000: 26-33

  8. PWR vessel flaw distribution development

    International Nuclear Information System (INIS)

    Rosinski, S.T.; Kennedy, E.L.; Foulds, J.R.; Kinsman, K.M.

    1990-01-01

    This paper reports on PWR pressure vessels which operate under NRC rules and regulatory guides intended to prevent failure of the vessels. Plants failing to meet the operating criteria specified under these rules and regulations are required to analytically demonstrate fitness for service in order to continue operation. The initial flaw size or distribution of initial vessel flaws is a key input to the required vessel integrity analyses. However, the flaw distribution assumed in the development of the NRC Regulations and recommended for the plant specific analyses is potentially over-conservative. This is because the distribution is based on the limited amount of vessel inspection data available at the time the criteria were being developed and does not take full advantage of the more recent and reliable domestic vessel inspection results. The U.S. Department of Energy is funding an effort through Sandia National Laboratories to investigate the possibility of developing a new flaw distribution based on the increased amount and improved reliability of domestic vessel inspection data. Results of Phase I of the program indicate that state-of-the-art NDE systems' capabilities are sufficient for development of a new flaw distribution that could ultimately provide life extension benefits over the presently required operating practice

  9. Nuclear reactor vessel decontamination systems

    International Nuclear Information System (INIS)

    McGuire, P. J.

    1985-01-01

    There is disclosed in the present application, a decontamination system for reactor vessels. The system is operatable without entry by personnel into the contaminated vessel before the decontamination operation is carried out and comprises an assembly which is introduced into the vertical cylindrical vessel of the typical boiling water reactor through the open top. The assembly includes a circular track which is centered by guideways permanently installed in the reactor vessel and the track guides opposed pairs of nozzles through which water under very high pressure is directed at the wall for progressively cutting and sweeping a tenacious radioactive coating as the nozzles are driven around the track in close proximity to the vessel wall. The whole assembly is hoisted to a level above the top of the vessel by a crane, outboard slides on the assembly brought into engagement with the permanent guideways and the assembly progressively lowered in the vessel as the decontamination operation progresses. The assembly also includes a low pressure nozzle which forms a spray umbrella above the high pressure nozzles to contain radioactive particles dislodged during the decontamination

  10. 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.)

  11. Effect of sintering temperature on the morphology and mechanical properties of PTFE membranes as a base substrate for proton exchange membrane

    Directory of Open Access Journals (Sweden)

    Nor Aida Zubir

    2002-11-01

    Full Text Available This paper reports the development of PTFE membranes as the base substrates for producing proton exchange membrane by using radiation-grafting technique. An aqueous dispersion of PTFE, which includes sodium benzoate, is cast in order to form suitable membranes. The casting was done by usinga pneumatically controlled flat sheet membrane-casting machine. The membrane is then sintered to fuse the polymer particles and cooled. After cooling process, the salt crystals are leached from the membrane by dissolution in hot bath to leave a microporous structure, which is suitable for such uses as a filtration membrane or as a base substrate for radiation grafted membrane in PEMFC. The effects of sintering temperature on the membrane morphology and tensile strength were investigated at 350oC and 385oC by using scanning electron microscopy (SEM and EX 20, respectively. The pore size and total void space are significantly smaller at higher sintering temperature employed with an average pore diameter of 11.78 nm. The tensile strength and tensile strain of sintered PTFE membrane at 385oC are approximately 19.02 + 1.46 MPa and 351.04 + 23.13 %, respectively. These results were indicated at 385oC, which represents significant improvements in tensile strength and tensile strain, which are nearly twice those at 350oC.

  12. Comparative Efficacy of Pulse-Spray Thrombolysis and Angioplasty Versus Surgical Salvage Procedures for Treatment of Recurrent Occlusion of PTFE Dialysis Access Grafts

    International Nuclear Information System (INIS)

    Polak, Joseph F.; Berger, Markus F.; Pagan-Marin, Heriberto; Aruny, John E.; Meyerovitz, Michael F.

    1998-01-01

    Purpose: To compare the efficacy of surgery versus pulse-spray thrombolysis and angioplasty in patients with recurrent thrombosis of polytetrafluoroethylene (PTFE) dialysis access grafts. Methods: We analyzed 96 consecutive interventions for thrombosed PTFE dialysis access grafts in 18 patients. Primary patency after thrombolysis and angioplasty (n= 25) was compared with primary patency following thrombectomy alone (n= 50) or thrombectomy followed by graft revision (n= 21) using life-table analysis. A Cox proportional hazards model that accounted for graft age and number of previous interventions was used to generate the relative risk for recurrent occlusion following therapy. Results: Life-table analysis showed that patency after thrombolysis and angioplasty was greater than that following thrombectomy alone (p= 0.02). After accounting for the age of the graft and the number of previous interventions (average six per patient), the relative risk for recurrent occlusion [3.0; 95% confidence intervals (CI): 1.5, 6.4] was greater for thrombectomy alone than for thrombolysis/angioplasty [0.6; CI = 0.3, 1.3]. The relative risks of repeat occlusion following thrombolysis/angioplasty [0.6; CI = 0.3, 1.3] and thrombectomy/surgical revision [1.0; CI = 0.5, 1.7] were similar. Conclusion: Outcome data from our retrospective study on recurrent thrombosis of PTFE dialysis access grafts suggest that thrombolysis/angioplasty is superior to thrombectomy alone, and equivalent to thrombectomy/surgical revision

  13. Proton/gamma relative thermoluminescence efficiencies of LiF:Mg,Cu,P+PTFE prepared at ININ and TLD-100H

    International Nuclear Information System (INIS)

    Avila, O.; Gonzalez, P.; Murillo, G.

    2009-10-01

    Properties of LiF:Mg,Cu,P+PTFE dosemeters developed at ININ have been investigated in order to evaluate their performance compared to those of equivalent commercial dosemeters. In this work both LiF:Mg,Cu,P+PTFE and TLD-100H pellets were exposed to low fluence 3 MeV protons and to low dose gamma radiation to evaluate experimental proton/gamma efficiencies. Gamma irradiation was performed using the Vic krad irradiator at ININ at varying doses between 25 and 500 mGy. For proton irradiation the Tandem Van de Graaff accelerator at ININ was used. Dosemeters were placed on a holder inside a scattering chamber where protons impinge on a gold target and scatter in all directions. The holder allows for several angular positions so that dosemeters receive proton fluence between 10 6 and 10 1 0 p/cm 2 . Experimental efficiency values found for LiF:Mg,Cu,P+PTFE and TLD-100H were 0.18 +- 03 and 0.23 +- 0.03, respectively. These results allow to confirm the reliability of the dosemeters developed at ININ. (Author)

  14. Gammatography of thick lead vessels

    International Nuclear Information System (INIS)

    Raghunath, V.M.; Bhatnagar, P.K.; Sundaram, V.M.

    1979-01-01

    Radiography, scintillation and GM counting and dose measurements using ionisation chamber equipment are commonly used for detecting flaws/voids in materials. The first method is mostly used for steel vessels and to a lesser extent thin lead vessels also and is essentially qualitative. Dose measuring techniques are used for very thick and large lead vessels for which high strength radioactive sources are required, with its inherent handling problems. For vessels of intermediate thicknesses, it is ideal to use a small strength source and a GM or scintillation counter assembly. At the Reactor Research Centre, Kalpakkam, such a system was used for checking three lead vessels of thicknesses varying from 38mm to 65mm. The tolerances specified were +- 4% variation in lead thickness. The measurements also revealed the non concentricity of one vessel which had a thickness varying from 38mm to 44mm. The second vessel was patently non-concentric and the dimensional variation was truly reproduced in the measurements. A third vessel was fabricated with careful control of dimensions and the measurements exhibited good concentricity. Small deviations were observed, attributable to imperfect bondings between steel and lead. This technique has the following advantages: (a) weaker sources used result in less handling problems reducing the personnel exposures considerably; (b) the sensitivity of the instrument is quite good because of better statistics; (c) the time required for scanning a small vessel is more, but a judicious use of a scintillometer for initial fast scan will help in reducing the total scanning time; (d) this method can take advantage of the dimensional variations themselves to get the calibration and to estimate the deviations from specified tolerances. (auth.)

  15. Dosimetric intercomparison in Cobalt 60 unities using TLD-100 crystals and CaSO{sub 4}: Dy + Ptfe; Intercomparacion dosimetrica en unidades de cobalto 60 usando cristales de TLD-100 y CaSO{sub 4}: Dy + PTFE

    Energy Technology Data Exchange (ETDEWEB)

    Gaona, E. [Universidad Autonoma Metropolitana Xochimilco, Mexico D.F. (Mexico); Azorin N, J. [Universidad Autonoma Metropolitana Iztapalapa, Mexico D.F. (Mexico); Perez P, M.A. [Instituto Nacional de Cancerologia, Mexico D.F. (Mexico); Castillo H, M. [Centro Medico Nacional 20 de Noviembre, ISSSTE, Mexico D.F. (Mexico); Flores F, F. [Unidad de Oncologia, Centro Medico Nacional, IMSS, Mexico D.F. (Mexico); Guzman R, L.V. [Unidad de Oncologia, Hospital General de Mexico, Mexico D.F. (Mexico)

    1999-07-01

    The purpose of this work is to design and construct a phantom in basis of thermoplastic polymer of methyl methacrylate that is reutilizable and which allows to do an analysis of the absorbed doses in thermoluminescent crystals (Tl) exposed to cobalt 60 to establish the dosimetric intercomparison in cobalt units which allows to do the follow-up of the Quality assurance programs, standardization of calibration procedures, dosimetry and TLD post intercomparison in radiotherapy. This work allows also prove new thermoluminescent materials of national manufacture developed by Juan Azorin and collaborators as the CaSO{sub 4}: Dy + Ptfe. This is a first study which is realized in Mexico with the system crystal-phantom for aims to intercomparison in cobalt 60 units. In this work participate eight unities of cobalt 60 of different trades belonging at four radiotherapy centers. The results of the dose intercomparison of the eight unities of cobalt 60 were in the range 0.95-1.13, taking in account that the values between 0.95 and 1.05 were considered acceptable in terms of the requirements by the standing legislation. (Author)

  16. BY FRUSTUM CONFINING VESSEL

    Directory of Open Access Journals (Sweden)

    Javad Khazaei

    2016-09-01

    Full Text Available Helical piles are environmentally friendly and economical deep foundations that, due to environmental considerations, are excellent additions to a variety of deep foundation alternatives available to the practitioner. Helical piles performance depends on soil properties, the pile geometry and soil-pile interaction. Helical piles can be a proper alternative in sensitive environmental sites if their bearing capacity is sufficient to support applied loads. The failure capacity of helical piles in this study was measured via an experimental research program that was carried out by Frustum Confining Vessel (FCV. FCV is a frustum chamber by approximately linear increase in vertical and lateral stresses along depth from top to bottom. Due to special geometry and applied bottom pressure, this apparatus is a proper choice to test small model piles which can simulate field stress conditions. Small scale helical piles are made with either single helix or more helixes and installed in fine grained sand with three various densities. Axial loading tests including compression and tension tests were performed to achieve pile ultimate capacity. The results indicate the helical piles behavior depends essentially on pile geometric characteristics, i.e. helix configuration and soil properties. According to the achievements, axial uplift capacity of helical model piles is about equal to usual steel model piles that have the helixes diameter. Helical pile compression bearing capacity is too sufficient to act as a medium pile, thus it can be substituted other piles in special geoenvironmental conditions. The bearing capacity also depends on spacing ratio, S/D, and helixes diameter.

  17. Vacuum vessel for thermonuclear device

    International Nuclear Information System (INIS)

    Hagiwara, Koji; Imura, Yasuya.

    1979-01-01

    Purpose: To provide constituted method for easily performing baking of vacuum vessel, using short-circuiting segments. Constitution: At the time of baking, one turn circuit is formed by the vacuum vessel and short-circuiting segments, and current transformer converting the one turn circuit into a secondary circuit by the primary coil and iron core is formed, and the vacuum vessel is Joule heated by an induction current from the primary coil. After completion of baking, the short-circuiting segments are removed. (Kamimura, M.)

  18. PWR vessel inspection performance improvements

    International Nuclear Information System (INIS)

    Blair Fairbrother, D.; Bodson, Francis

    1998-01-01

    A compact robot for ultrasonic inspection of reactor vessels has been developed that reduces setup logistics and schedule time for mandatory code inspections. Rather than installing a large structure to access the entire weld inspection area from its flange attachment, the compact robot examines welds in overlapping patches from a suction cup anchor to the shell wall. The compact robot size allows two robots to be operated in the vessel simultaneously. This significantly reduces the time required to complete the inspection. Experience to date indicates that time for vessel examinations can be reduced to fewer than four days. (author)

  19. Special enclosure for a pressure vessel

    International Nuclear Information System (INIS)

    Wedellsborg, B.W.; Wedellsborg, U.W.

    1993-01-01

    A pressure vessel enclosure is described comprising a primary pressure vessel, a first pressure vessel containment assembly adapted to enclose said primary pressure vessel and be spaced apart therefrom, a first upper pressure vessel jacket adapted to enclose the upper half of said first pressure vessel containment assembly and be spaced apart therefrom, said upper pressure vessel jacket having an upper rim and a lower rim, each of said rims connected in a slidable relationship to the outer surface of said first pressure vessel containment assembly, mean for connecting in a sealable relationship said upper rim of said first upper pressure vessel jacket to the outer surface of said first pressure vessel containment assembly, means for connecting in a sealable relationship said lower rim of said first upper pressure vessel jacket to the outer surface of said first pressure vessel containment assembly, a first lower pressure vessel jacket adapted to enclose the lower half of said first pressure vessel containment assembly and be spaced apart therefrom, said lower pressure vessel jacket having an upper rim connected in a slidable relationship to the outer surface of said first pressure vessel containment assembly, and means for connecting in a sealable relationship said upper rim of said first lower pressure vessel jacket to the outer surface of said first pressure vessel containment assembly, a second upper pressure vessel jacket adapted to enclose said first upper pressure vessel jacket and be spaced apart therefrom, said second upper pressure vessel jacket having an upper rim and a lower rim, each of said rims adapted to slidably engage the outer surface of said first upper pressure vessel jacket, means for sealing said rims, a second lower pressure vessel jacket adapted to enclose said first lower pressure vessel jacket and be spaced apart therefrom

  20. Measurements to determine the sulfuric acid dew point and the SO sub 3 concentration in flue gas of power plant vessels. Messungen zur Bestimmung des Saeuretaupunktes und der SO sub 3 -Konzentration im Rauchgas von Kraftwerkskesseln

    Energy Technology Data Exchange (ETDEWEB)

    Derichs, W.; Menden, W. (RWE Energie AG, Bergheim (Germany)); Ebel, P.K. (Apparatebau Hundsbach GmbH, Baden-Baden (Germany))

    1990-01-01

    Among the customary methods of dew point determination, the technique of recording the increase in conductivity between two electrodes at the moment of acid condensing onto them, and measuring at the same time the temperature of the sensor, is appropriate to determine the sulfuric acid dew point in dust-laden flue gas. By means of the sensitivity of a newly developed sensor, the accuracy of the measurement method could be improved to such an extent that also low acid dew points and rapid changes can be recorded reliably. Measurements have shown that the acid dew point primarily depends on the SO{sub 3} content which is substantially determined by the sulfur content of the fuel and the type of flue gas ducts. Further influential quantities include flue gas humidity, air surplus, other gaseous flue gas components such as HCl and HF, as well as the quantity, composition and temperature-dependent adsorption capability of the flue dusts. (orig./BBR).

  1. Dosimetric intercomparison in Cobalt 60 unities using TLD-100 crystals and CaSO4: Dy + Ptfe

    International Nuclear Information System (INIS)

    Gaona, E.; Azorin N, J.; Perez P, M.A.; Castillo H, M.; Flores F, F.; Guzman R, L.V.

    1999-01-01

    The purpose of this work is to design and construct a phantom in basis of thermoplastic polymer of methyl methacrylate that is reutilizable and which allows to do an analysis of the absorbed doses in thermoluminescent crystals (Tl) exposed to cobalt 60 to establish the dosimetric intercomparison in cobalt units which allows to do the follow-up of the Quality assurance programs, standardization of calibration procedures, dosimetry and TLD post intercomparison in radiotherapy. This work allows also prove new thermoluminescent materials of national manufacture developed by Juan Azorin and collaborators as the CaSO 4 : Dy + Ptfe. This is a first study which is realized in Mexico with the system crystal-phantom for aims to intercomparison in cobalt 60 units. In this work participate eight unities of cobalt 60 of different trades belonging at four radiotherapy centers. The results of the dose intercomparison of the eight unities of cobalt 60 were in the range 0.95-1.13, taking in account that the values between 0.95 and 1.05 were considered acceptable in terms of the requirements by the standing legislation. (Author)

  2. Electrode kinetics of ethanol oxidation on novel CuNi alloy supported catalysts synthesized from PTFE suspension

    Science.gov (United States)

    Sen Gupta, S.; Datta, J.

    An understanding of the kinetics and mechanism of the electrochemical oxidation of ethanol is of considerable interest for the optimization of the direct ethanol fuel cell. In this paper, the electro-oxidation of ethanol in sodium hydroxide solution has been studied over 70:30 CuNi alloy supported binary platinum electrocatalysts. These comprised mixed deposits of Pt with Ru or Mo. The electrodepositions were carried out under galvanostatic condition from a dilute suspension of polytetrafluoroethylene (PTFE) containing the respective metal salts. Characterization of the catalyst layers by scanning electron microscope (SEM)-energy dispersive X-ray (EDX) indicated that this preparation technique yields well-dispersed catalyst particles on the CuNi alloy substrate. Cyclic voltammetry, polarization study and electrochemical impedance spectroscopy were used to investigate the kinetics and mechanism of ethanol electro-oxidation over a range of NaOH and ethanol concentrations. The relevant parameters such as Tafel slope, charge transfer resistance and the reaction orders in respect of OH - ions and ethanol were determined.

  3. Coupling Sodium Dodecyl Sulfate–Capillary Polyacrylamide Gel Electrophoresis with MALDI-TOF-MS via a PTFE Membrane

    Science.gov (United States)

    Lu, Joann J.; Zhu, Zaifang; Wang, Wei; Liu, Shaorong

    2011-01-01

    Sodium dodecyl sulfate (SDS)–polyacrylamide gel electrophoresis (PAGE) is a fundamental analytical technique for proteomic research, and SDS–capillary gel electrophoresis (CGE) is its miniaturized version. Compared to conventional slab-gel electrophoresis, SDS-CGE has many advantages such as increased separation efficiency, reduced separation time and automated operation. SDS-CGE is not widely accepted in proteomic research primarily due to the difficulties in identifying the well-resolved proteins. MALDI–TOF–MS is an outstanding platform for protein identifications. Coupling the two would solve the problem but is extremely challenging because the MS detector has no access to the SDS-CGE resolved proteins and the SDS interferes with MS detection. In this work we introduce an approach to address these issues. We discover that poly(tetrafluoroethylene) (PTFE) membranes are excellent materials for collecting SDS-CGE separated proteins. We demonstrate that we can wash off the SDS bound to the collected proteins and identify these proteins on-membrane with MALDI-TOF-MS. We also show that we can immunoblot and Coomassie-stain the proteins collected on these membranes. PMID:21309548

  4. Normal Force Influence on 3D Texture Parameters Characterizing the Friction Couple Steel – PBT + 10 % PTFE

    Directory of Open Access Journals (Sweden)

    C. Georgescu

    2014-03-01

    Full Text Available This study presents the influence of the normal force on the surface quality of the friction couple steel – polybutylene terephthalate (PBT + 10 % polytetrafluoroethylene (PTFE. There were calculated the average values of the amplitude and functional parameters, as obtained from investigating square areas on the wear tracks, with the help of a proposed methodology, for initial and tested surfaces generated on the blocks and on counterpart ring made of rolling bearing steel, for the following test conditions: three normal forces (F = 1 N, F = 2.5 N and F =5 N, three sliding speeds (v = 0.25 m/s, v = 0.50 m/s and v = 0.75 m/s and a sliding distance of L = 7500 m. The conclusion of the research study was that the tested normal force range has an insignificant influence on the surface quality for the tested materials and parameters. This friction couple could be recommended for variable conditions (speed and load in dry regimes.

  5. Histopathological Evaluation of a Hydrophobic Terpolymer (PTFE-PVD-PP) as an Implant Material for Nonpenetrating Very Deep Sclerectomy.

    Science.gov (United States)

    Leszczynski, Rafal; Gumula, Teresa; Stodolak-Zych, Ewa; Pawlicki, Krzysztof; Wieczorek, Jaroslaw; Kajor, Maciej; Blazewicz, Stanislaw

    2015-08-01

    The purpose of the study was to assess the biocompatibility of porous terpolymer (polytetrafluoroethylene-co-polyvinylidene fluoride-co-polypropylene, PTFE-PVDF-PP) membranes as an implant material to be placed during nonpenetrating very deep sclerectomy (NPVDS). Another study objective was to determine whether the polymer membrane under investigation could be used to manufacture a new-generation implant, which would actively delay the process of fistula closure and facilitate aqueous humor drainage. Histological response and tissue tolerance of the implant material were assessed. The study was performed on 38 eyeballs of 19 New Zealand white rabbits (19 implanted, 19 control). Histological assessment was carried out between 2 and 52 weeks after surgery. We routinely assessed inflammatory infiltrate, neovascularization, hemorrhage, and stromal edema as well as connective tissue attachment to the implant and adjacent tissues. At 52 weeks of observation, a statistically significant difference was revealed between the study and control groups in terms of resorptive granulation, tissue, and the inflammatory infiltrate. No features of acute inflammatory response to the implant were observed, and there was an absence of histological features of acute inflammatory infiltrates and subsidence of chronic inflammatory infiltrates and resorptive granulation over time. Slight fibrotic response and insignificant changes in neighboring eye tissues all indicate good tolerance to bioimplant materials. This allows for some optimism regarding the use of hydrophobic terpolymer in the construction of new intrascleral implants. However, the ultimate decision regarding its usefulness and safety in the treatment of glaucoma requires further investigation.

  6. 2013 West Coast Vessel Tracklines

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Automatic Identification Systems (AIS) are a navigation safety device that transmits and monitors the location and characteristics of many vessels in U.S. and...

  7. 2011 West Coast Vessel Tracklines

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Automatic Identification Systems (AIS) are a navigation safety device that transmits and monitors the location and characteristics of many vessels in U.S. and...

  8. 2013 Great Lakes Vessel Tracklines

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Automatic Identification Systems (AIS) are a navigation safety device that transmits and monitors the location and characteristics of many vessels in U.S. and...

  9. 2011 Great Lakes Vessel Tracklines

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Automatic Identification Systems (AIS) are a navigation safety device that transmits and monitors the location and characteristics of many vessels in U.S. and...

  10. 2011 East Coast Vessel Tracklines

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Automatic Identification Systems (AIS) are a navigation safety device that transmits and monitors the location and characteristics of many vessels in U.S. and...

  11. Coastal Discard Logbook Survey (Vessels)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains data on the type and amount of marine resources that are discarded or interacted with by vessels that are selected to report to the Southeast...

  12. SC/OQ Vessel Database

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data tables holding information for the Surf Clam/Ocean Quahog vessel and dealer/processor logbooks (negative and positive), as well as individual tag information...

  13. Vessel Permit System Data Set

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — GARFO issues federal fishing permits annually to owners of fishing vessels who fish in the Greater Atlantic region, as required by federal regulation. These permits...

  14. Reactor pressure vessel status report

    International Nuclear Information System (INIS)

    Strosnider, J.; Wichman, K.; Elliot, B.

    1994-12-01

    This report gives a brief description of the reactor pressure vessel (RPV), followed by a discussion of the radiation embrittlement of RPV beltline materials and the two indicators for measuring embrittlement, the end-of-license (EOL) reference temperature and the EOL upper-shelf energy. It also summarizes the GL 92-01 effort and presents, for all 37 boiling water reactor plants and 74 pressurized water reactor plants in the United States, the current status of compliance with regulatory requirements related to ensuring RPV integrity. The staff has evaluated the material data needed to predict neutron embrittlement of the reactor vessel beltline materials. These data will be stored in a computer database entitled the reactor vessel integrity database (RVID). This database will be updated annually to reflect the changes made by the licensees in future submittals and will be used by the NRC staff to assess the issues related to vessel structural integrity

  15. Reactor-vessel-sectioning demonstration

    International Nuclear Information System (INIS)

    Lundgren, R.A.

    1981-07-01

    A successful technical demonstration of simulated reactor vessel sectioning was completed using the combined techniques of air arc gouging and flame cutting. A 4-ft x 3-ft x 9-in. thick sample was fabricated of A36 carbon steel to simulate a reactor vessel wall. A 1/4-in layer of stainless steel (SS) was tungsten inert gas (TIG)-welded to the carbon steel. Several techniques were considered to section the simulated reactor vessel: an air arc gouger was chosen to penetrate the stainless steel, and flame cutting was selected to sever the carbon steel. After the simulated vessel was successfully cut from the SS side, another cut was made, starting from the carbon steel side. This cut was also successful. Cutting from the carbon steel side has the advantages of cost reduction since the air arc gouging step is eliminated and contamination controlled because the molten metal is blown inward

  16. Power reactor pressure vessel benchmarks

    International Nuclear Information System (INIS)

    Rahn, F.J.

    1978-01-01

    A review is given of the current status of experimental and calculational benchmarks for use in understanding the radiation embrittlement effects in the pressure vessels of operating light water power reactors. The requirements of such benchmarks for application to pressure vessel dosimetry are stated. Recent developments in active and passive neutron detectors sensitive in the ranges of importance to embrittlement studies are summarized and recommendations for improvements in the benchmark are made. (author)

  17. Prosopomorphic vessels from Moesia Superior

    Directory of Open Access Journals (Sweden)

    Nikolić Snežana

    2008-01-01

    Full Text Available The prosopomorphic vessels from Moesia Superior had the form of beakers varying in outline but similar in size. They were wheel-thrown, mould-made or manufactured by using a combination of wheel-throwing and mould-made appliqués. Given that face vessels are considerably scarcer than other kinds of pottery, more than fifty finds from Moesia Superior make an enviable collection. In this and other provinces face vessels have been recovered from military camps, civilian settlements and necropolises, which suggests that they served more than one purpose. It is generally accepted that the faces-masks gave a protective role to the vessels, be it to protect the deceased or the family, their house and possessions. More than forty of all known finds from Moesia Superior come from Viminacium, a half of that number from necropolises. Although tangible evidence is lacking, there must have been several local workshops producing face vessels. The number and technological characteristics of the discovered vessels suggest that one of the workshops is likely to have been at Viminacium, an important pottery-making centre in the second and third centuries.

  18. Vacuum vessel for thermonuclear device

    International Nuclear Information System (INIS)

    Kikuchi, Mitsuru; Kurita, Gen-ichi; Onozuka, Masaki; Suzuki, Masaru.

    1997-01-01

    Heat of inner walls of a vacuum vessel that receive radiation heat from plasmas by way of first walls is removed by a cooling medium flowing in channels for cooling the inner walls. Nuclear heat generation of constitutional materials of the vacuum vessel caused by fast neutrons and γ rays is removed by a cooling medium flowing in cooling channels disposed in the vacuum vessel. Since the heat from plasmas and the nuclear heat generation are removed separately, the amount of the cooling medium flowing in the channels for cooling inner walls is increased for cooling a great amount of heat from plasmas while the amount of the cooling medium flowing in the channels for cooling the inside of the vacuum vessel is reduced for cooling the small amount of nuclear heat generation. Since the amount of the cooling medium can thus be optimized, the capacity of the facilities for circulating the cooling medium can be reduced. In addition, since the channels for cooling the inner walls and the channels of cooling medium formed in the vacuum vessel are disposed to the inner walls of the vacuum vessel on the side opposite to plasmas, integrity of the channels relative to leakage of the cooling medium can be ensured. (N.H.)

  19. Vacuum vessel for thermonuclear device

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, Mitsuru; Kurita, Gen-ichi [Japan Atomic Energy Research Inst., Tokyo (Japan); Onozuka, Masaki; Suzuki, Masaru

    1997-07-31

    Heat of inner walls of a vacuum vessel that receive radiation heat from plasmas by way of first walls is removed by a cooling medium flowing in channels for cooling the inner walls. Nuclear heat generation of constitutional materials of the vacuum vessel caused by fast neutrons and {gamma} rays is removed by a cooling medium flowing in cooling channels disposed in the vacuum vessel. Since the heat from plasmas and the nuclear heat generation are removed separately, the amount of the cooling medium flowing in the channels for cooling inner walls is increased for cooling a great amount of heat from plasmas while the amount of the cooling medium flowing in the channels for cooling the inside of the vacuum vessel is reduced for cooling the small amount of nuclear heat generation. Since the amount of the cooling medium can thus be optimized, the capacity of the facilities for circulating the cooling medium can be reduced. In addition, since the channels for cooling the inner walls and the channels of cooling medium formed in the vacuum vessel are disposed to the inner walls of the vacuum vessel on the side opposite to plasmas, integrity of the channels relative to leakage of the cooling medium can be ensured. (N.H.)

  20. Lymphatic vessels assessment in feline mammary tumours

    International Nuclear Information System (INIS)

    Sarli, Giuseppe; Sassi, Francesco; Brunetti, Barbara; Rizzo, Antonio; Diracca, Laura; Benazzi, Cinzia

    2007-01-01

    The lymphatic vessels play a crucial role in a variety of human cancers since tumour cell lymphatic invasion significantly influences prognosis. It is not known if pre-existing lymphatics are enough for tumour dissemination or de novo development is necessary. VEGFR-3 is an angiogenetic mediator for both lymphatic and blood vessels during embryonic development, and only for lymphatics after birth. VEGF is a mediator of both vasculogenesis and angiogenesis, regulates the growth of lymphatics in various experimental models, and is produced in many solid tumours. CD44 mediates hyaluronic acid (HA)-dependent cell adhesion: besides promoting invasion, this interaction also supports neoangiogenesis that indirectly stimulates tumour cell proliferation. The expression of VEGF-C (Vascular Endothelial Growth Factor – C), its receptor VEGFR-3 and CD44, were studied on feline mammary samples to assess the importance of lymphangiogenesis and lymphangiotrophism in neoplasia. Samples were taken from six normal mammary glands (NMG), ten benign (BT) and 32 malignant (MT) tumours. Immunohistochemical laminin/VEGFR-3 double stain, VEGF-C and CD44 stains were applied to 4 μm-thick sections, and their expression evaluated in intratumoral/extratumoral and intramammary/extramammary fields. All groups revealed a higher number of lymphatics in the extratumoral/extramammary areas. VEGF-C expression in the epithelium paralleled the number of positive vessels in the NMG, BT and MT, whereas VEGF-C higher expression was noted in the intratumoral fields only in infiltrating MT. CD44 score was lower in extratumoral than intratumoral fields in tumours and showed a significant increase in extramammary/extratumoral fields from NMG to MT. Pearson test showed a significant and inversely proportional correlation between CD44 expression and the number of lymphatic vessels with VEGFR-3 in malignant infiltrating tumours. The number of both VEGFR-3 positive and negative lymphatics in the extratumoral

  1. Automated method for identification and artery-venous classification of vessel trees in retinal vessel networks.

    Science.gov (United States)

    Joshi, Vinayak S; Reinhardt, Joseph M; Garvin, Mona K; Abramoff, Michael D

    2014-01-01

    The separation of the retinal vessel network into distinct arterial and venous vessel trees is of high interest. We propose an automated method for identification and separation of retinal vessel trees in a retinal color image by converting a vessel segmentation image into a vessel segment map and identifying the individual vessel trees by graph search. Orientation, width, and intensity of each vessel segment are utilized to find the optimal graph of vessel segments. The separated vessel trees are labeled as primary vessel or branches. We utilize the separated vessel trees for arterial-venous (AV) classification, based on the color properties of the vessels in each tree graph. We applied our approach to a dataset of 50 fundus images from 50 subjects. The proposed method resulted in an accuracy of 91.44% correctly classified vessel pixels as either artery or vein. The accuracy of correctly classified major vessel segments was 96.42%.

  2. The TPX vacuum vessel and in-vessel components

    International Nuclear Information System (INIS)

    Heitzenroeder, P.; Bialek, J.; Ellis, R.; Kessel, C.; Liew, S.

    1994-01-01

    The Tokamak Physics Experiment (TPX) is a superconducting tokamak with double-null diverters. TPX is designed for 1,000-second discharges with the capability of being upgraded to steady state operation. High neutron yields resulting from the long duration discharges require that special consideration be given to materials and maintainability. A unique feature of the TPX is the use of a low activation, titanium alloy vacuum vessel. Double-wall vessel construction is used since it offers an efficient solution for shielding, bakeout and cooling. Contained within the vacuum vessel are the passive coil system, Plasma Facing Components (PFCs), magnetic diagnostics, and the internal control coils. All PFCs utilize carbon-carbon composites for exposed surfaces

  3. Clay Corner: Recreating Chinese Bronze Vessels.

    Science.gov (United States)

    Gamble, Harriet

    1998-01-01

    Presents a lesson where students make faux Chinese bronze vessels through slab or coil clay construction after they learn about the history, function, and design of these vessels. Utilizes a variety of glaze finishes in order to give the vessels an aged look. Gives detailed guidelines for creating the vessels. (CMK)

  4. Vacuum vessel for thermonuclear device

    International Nuclear Information System (INIS)

    Kikuchi, Mitsuru; Nagashima, Keisuke; Suzuki, Masaru; Onozuka, Masaki.

    1997-01-01

    A vacuum vessel main body and structural members at the inside and the outside of the vacuum vessel main body are constituted by structural materials activated by irradiation of neutrons from plasmas such as stainless steels. Shielding members comprising tungsten or molybdenum are disposed on the surface of the vacuum vessel main body and the structural members of the inside and the outside of the main body. The shielding members have a function also as first walls or a seat member for the first walls. Armor tiles may be disposed to the shielding members. The shielding members and the armor tiles are secured to a securing seat member disposed, for example, to an inner plate of the vacuum vessel main body by bolts. Since the shielding members are disposed, it is not necessary to constitute the vacuum vessel main body and the structural members at the inside and the outside thereof by using a low activation material which is less activated, such as a titanium alloy. (I.N.)

  5. Vacuum vessel for thermonuclear device

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, Mitsuru; Nagashima, Keisuke [Japan Atomic Energy Research Inst., Tokyo (Japan); Suzuki, Masaru; Onozuka, Masaki

    1997-07-11

    A vacuum vessel main body and structural members at the inside and the outside of the vacuum vessel main body are constituted by structural materials activated by irradiation of neutrons from plasmas such as stainless steels. Shielding members comprising tungsten or molybdenum are disposed on the surface of the vacuum vessel main body and the structural members of the inside and the outside of the main body. The shielding members have a function also as first walls or a seat member for the first walls. Armor tiles may be disposed to the shielding members. The shielding members and the armor tiles are secured to a securing seat member disposed, for example, to an inner plate of the vacuum vessel main body by bolts. Since the shielding members are disposed, it is not necessary to constitute the vacuum vessel main body and the structural members at the inside and the outside thereof by using a low activation material which is less activated, such as a titanium alloy. (I.N.)

  6. Molten material-containing vessel

    International Nuclear Information System (INIS)

    Akagawa, Katsuhiko

    1998-01-01

    The molten material-containing vessel of the present invention comprises a vessel main body having an entrance opened at the upper end, a lid for closing the entrance, an outer tube having an upper end disposed at the lower surface of the lid, extended downwardly and having an closed lower end and an inner tube disposed coaxially with the outer tube. When a molten material is charged from the entrance to the inside of the vessel main body of the molten material-containing vessel and the entrance is closed by the lid, the outer tube and the inner tube are buried in the molten material in the vessel main body, accordingly, a fluid having its temperature elevated by absorption of the heat of the molten material rises along the inner circumferential surface of the outer tube, abuts against the lower surface of the lid and cooled by exchanging heat with the lid and forms a circulating flow. Since the heat in the molten material is continuously absorbed by the fluid, transferred to the lid and released from the lid to the atmospheric air, heat releasing efficiency can be improved compared with conventional cases. (N.H.)

  7. Emergency venting of pressure vessels

    International Nuclear Information System (INIS)

    Steinkamp, H.

    1995-01-01

    With the numerical codes developed for safety analysis the venting of steam vessel can be simulated. ATHLET especially is able to predict the void fraction depending on the vessel height. Although these codes contain a one-dimensional model they allow the description of complex geometries due to the detailed nodalization of the considered apparatus. In chemical reactors, however, the venting process is not only influenced by the flashing behaviour but additionally by the running chemical reaction in the vessel. Therefore the codes used for modelling have to consider the kinetics of the chemical reaction. Further multi-component systems and dissolving processes have to be regarded. In order to preduct the fluid- and thermodynamic process it could be helpful to use 3-dimensional codes in combination with the one-dimensional codes as used in nuclear industry to get a more detailed describtion of the running processes. (orig./HP)

  8. Development of Catamaran Fishing Vessel

    Directory of Open Access Journals (Sweden)

    A. Jamaluddin

    2010-11-01

    Full Text Available Multihull due to a couple of advantages has been the topic of extensive research work in naval architecture. In this study, a series of investigation of fishing vessel to save fuel energy was carried out at ITS. Two types of ship models, monohull (round bilge and hard chine and catamaran, a boat with two hulls (symmetrical and asymmetrical were developed. Four models were produced physically and numerically, tested (towing tank and simulated numerically (CFD code. The results of the two approaches indicated that the catamaran mode might have drag (resistance smaller than those of monohull at the same displacement. A layout of catamaran fishing vessel, proposed here, indicates the freedom of setting the deck equipments for fishing vessel.

  9. 33 CFR 90.3 - Pushing vessel and vessel being pushed: Composite unit.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Pushing vessel and vessel being... HOMELAND SECURITY INLAND NAVIGATION RULES INLAND RULES: INTERPRETATIVE RULES § 90.3 Pushing vessel and vessel being pushed: Composite unit. Rule 24(b) of the Inland Rules states that when a pushing vessel and...

  10. 33 CFR 82.3 - Pushing vessel and vessel being pushed: Composite unit.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Pushing vessel and vessel being... HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES 72 COLREGS: INTERPRETATIVE RULES § 82.3 Pushing vessel and vessel being pushed: Composite unit. Rule 24(b) of the 72 COLREGS states that when a pushing vessel and a...

  11. Containment vessel design and practice

    International Nuclear Information System (INIS)

    Bangash, Y.

    1983-01-01

    The state of the art of analysis and design of the concrete containment vessels required for BWR and PWR is reviewed. A step-by-step critical appraisal of the existing work is given. Elastic, inelastic and cracking conditions under extreme loads are fully discussed. Problems associated with these structures are highlighted. A three-dimensional finite element analysis is included to cater for service, overload and dynamic cracking of such structures. Missile impact and seismic effects are included in this work. The second analysis is known as the limit state analysis, which is given to design such vessels for any kind of load. (U.K.)

  12. Stress analysis of pressure vessels

    International Nuclear Information System (INIS)

    Kim, B.K.; Song, D.H.; Son, K.H.; Kim, K.S.; Park, K.B.; Song, H.K.; So, J.Y.

    1979-01-01

    This interim report contains the results of the effort to establish the stress report preparation capability under the research project ''Stress analysis of pressure vessels.'' 1978 was the first year in this effort to lay the foundation through the acquisition of SAP V structural analysis code and a graphic terminal system for improved efficiency of using such code. Software programming work was developed in pre- and post processing, such as graphic presentation of input FEM mesh geometry and output deformation or mode shope patterns, which was proven to be useful when using the FEM computer code. Also, a scheme to apply fracture mechanics concept was developed in fatigue analysis of pressure vessels. (author)

  13. Vessel dilatation in coronary angiograms

    International Nuclear Information System (INIS)

    Hinterauer, L.; Goebel, N.

    1983-01-01

    Amongst 166 patients with aneurysms, ectasia or megaloarteries shown on coronary angiograms, 86.1% had dilated vessels as part of generalised coronary sclerosis (usually in patients with three-vessel disease). In 9%, dilatation was of iatrogenic origin and in 4.8% it was idiopathic. One patient had Marfan's syndrome. Amongst 9 000 patients, there were eight with megalo-arteries without stenosis; six of these had atypical angina and three suffered an infarct. Patients with definite dilatation of the coronary artery and stagnation of contrast flow required treatment. (orig.) [de

  14. Vessel dilatation in coronary angiograms

    Energy Technology Data Exchange (ETDEWEB)

    Hinterauer, L.; Goebel, N.

    1983-11-01

    Amongst 166 patients with aneurysms, ectasia or megaloarteries shown on coronary angiograms, 86.1% had dilated vessels as part of generalised coronary sclerosis (usually in patients with three-vessel disease). In 9%, dilatation was of iatrogenic origin and in 4.8% it was idiopathic. One patient had Marfan's syndrome. Amongst 9 000 patients, there were eight with megalo-arteries without stenosis; six of these had atypical angina and three suffered an infarct. Patients with definite dilatation of the coronary artery and stagnation of contrast flow required treatment.

  15. A novel structure of scalable air-cathode without Nafion and Pt by rolling activated carbon and PTFE as catalyst layer in microbial fuel cells.

    Science.gov (United States)

    Dong, Heng; Yu, Hongbing; Wang, Xin; Zhou, Qixing; Feng, Junli

    2012-11-01

    Single chambered air-cathode microbial fuel cells (MFCs) are promising to be scaled up as sustainable wastewater treatment systems. However, the current air-cathode made by brushing noble metal catalyst and Nafion binder onto carbon matrix becomes one of the biggest bottlenecks for the further development of MFCs due to its high cost, huge labor-consuming and less accuracy. A novel structure of air-cathode was constructed here by rolling activated carbon (AC) and polytetrafluoroethylene (PTFE) as catalyst layer to enhance the reproducibility and improve the performance by an optimized three-phase interface (TPI). Air-cathodes with AC/PTFE ratios of 3, 5, 6, 8 and 11 in the catalyst layer were prepared, and the physical and electrochemical techniques were employed to investigate their surface microstructure and electrochemical characteristics. Uniform cross-linked ropiness networks were observed from the catalyst layer of all the cathodes and increased as the AC/PTFE ratio decreased, while the exchange currents were positively related to this ratio. Maximum power densities (MPDs) decreased as follows: AC/PTFE = 6 (802 mW m(-2) at 3.4 A m(-2)), 5 (704 mW m(-2) at 2.2 mA m(-2)), 8 (647 mW m(-2) at 2.2 A m(-2)), 3 (597 mW m(-2) at 2.1 A m(-2)) and 11 (584 mW m(-2) at 2.0 mA m(-2)), which was due to the changes of both the capacitance characteristics and conductivities according to the electrochemical impedance spectrum (EIS) analysis. This study demonstrated that inexpensive, highly reproducible, high performance and scalable air-cathode can be produced by rolling method without using noble metal and expensive binder. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Non-proximate mass spectrometry using a heated 1-m long PTFE tube and an air-tight APCI ion source

    International Nuclear Information System (INIS)

    Usmanov, Dilshadbek T.; Hiraoka, Kenzo; Wada, Hiroshi; Matsumura, Masaya; Sanada-Morimura, Sachiyo; Nonami, Hiroshi; Yamabe, Shinichi

    2017-01-01

    Direct and rapid trace-level gas analysis is highly needed in various fields such as safety and security, quality control, food analysis, and forensic medicine. In many cases, the real samples are bulky and are not accessible to the space-limited ion source of the mass spectrometer. In order to circumvent this problem, we developed an airtight atmospheric-pressure chemical ionization (APCI) ion source equipped with a flexible 1-m-long, 2-mm-i.d. PTFE sniffing tube. The ambient air bearing sample gas was sucked into the heated PTFE tube (130 °C) and was transported to the air-tight ion source without using any extra pumping system or a Venturi device. Analytes were ionized by an ac corona discharge located at 1.5 mm from the inlet of the mass spectrometer. By using the airtight ion source, all the ionized gas in the ion source was introduced into the vacuum of the mass spectrometer via only the evacuation of the mass spectrometer (1.6 l min"−"1). Sub-pg limits of detection were obtained for carbaryl and trinitrotoluene. Owing to its flexibility and high sensitivity, the sniffing tube coupled with a mass spectrometer can be used as the stethoscope for the high-sensitive gas analysis. The experimental results obtained for drugs, hydrogen peroxide and small alkanes were discussed by DFT calculations. - Highlights: • Non-proximate mass spectrometry for the trace-level gas analysis was developed. • Using a 1-m long flexible PTFE tube, it can be applicable to complicated-shape real-world samples. • By atmospheric pressure chemical ionization in the airtight ion source, sub-pg limits of detection were attained. • Adsorption of less-volatility compounds was negligible with the tube temperature at 130° C. • Novel experimental results obtained were fully examined by density functional theory calculations.

  17. Non-proximate mass spectrometry using a heated 1-m long PTFE tube and an air-tight APCI ion source

    Energy Technology Data Exchange (ETDEWEB)

    Usmanov, Dilshadbek T. [Clean Energy Research Center, University of Yamanashi, Takeda-4, Kofu, Yamanashi, 400-8511 (Japan); Institute of Ion-Plasma and Laser Technologies, Durmon Yoli Street 33, 100125, Tashkent (Uzbekistan); Hiraoka, Kenzo, E-mail: hiraoka@yamanashi.ac.jp [Clean Energy Research Center, University of Yamanashi, Takeda-4, Kofu, Yamanashi, 400-8511 (Japan); Wada, Hiroshi [Kyushu Okinawa Agricultural Research Center, National Agriculture and Food Research Organization, 496 Izumi, Chikugo, Fukuoka 833-0041 (Japan); Matsumura, Masaya; Sanada-Morimura, Sachiyo [Kyushu Okinawa Agricultural Research Center, National Agriculture and Food Research Organization, Suya 2421, shiKo, Kumamoto 861-1192 (Japan); Nonami, Hiroshi [Plant Biophysics/Biochemistry Research Laboratory, Faculty of Agriculture, Ehime University, 3-5-7 T Tarumi, 790-0905, Matsuyama (Japan); Yamabe, Shinichi, E-mail: yamabesh@gmail.com [Department of Material Science, Nara Institute of Science and Technology, Takayama-cho, 8916-5, Ikoma, Nara, 630−0101 (Japan)

    2017-06-22

    Direct and rapid trace-level gas analysis is highly needed in various fields such as safety and security, quality control, food analysis, and forensic medicine. In many cases, the real samples are bulky and are not accessible to the space-limited ion source of the mass spectrometer. In order to circumvent this problem, we developed an airtight atmospheric-pressure chemical ionization (APCI) ion source equipped with a flexible 1-m-long, 2-mm-i.d. PTFE sniffing tube. The ambient air bearing sample gas was sucked into the heated PTFE tube (130 °C) and was transported to the air-tight ion source without using any extra pumping system or a Venturi device. Analytes were ionized by an ac corona discharge located at 1.5 mm from the inlet of the mass spectrometer. By using the airtight ion source, all the ionized gas in the ion source was introduced into the vacuum of the mass spectrometer via only the evacuation of the mass spectrometer (1.6 l min{sup −1}). Sub-pg limits of detection were obtained for carbaryl and trinitrotoluene. Owing to its flexibility and high sensitivity, the sniffing tube coupled with a mass spectrometer can be used as the stethoscope for the high-sensitive gas analysis. The experimental results obtained for drugs, hydrogen peroxide and small alkanes were discussed by DFT calculations. - Highlights: • Non-proximate mass spectrometry for the trace-level gas analysis was developed. • Using a 1-m long flexible PTFE tube, it can be applicable to complicated-shape real-world samples. • By atmospheric pressure chemical ionization in the airtight ion source, sub-pg limits of detection were attained. • Adsorption of less-volatility compounds was negligible with the tube temperature at 130° C. • Novel experimental results obtained were fully examined by density functional theory calculations.

  18. Examination of the discharge mechanism of Li/CF(x) cells: Comparison of the electrochemical reduction mechanisms of PTFE and (CF(x))n by lithium

    Science.gov (United States)

    Baxam, Carl C.; Margalit, N.

    1991-01-01

    Swelling of (CF(x))(sub n) electrodes in commercial Li/(CF(x))(sub n) cells presents a limiting factor in cell design optimization. Examination of cathodes from such cells, after discharge, reveals a relation between cell operating temperatures and cathode swelling. Attempts to explain the swelling using the prevailing model for the cathode reaction have failed. A more suitable reaction mechanism is proposed based on the observed behavior of (CF(x))(sub n) electrodes on discharge and a comparison of the reaction products of (CF(x))(sub n) and polytetra fluoroethylene (PTFE) with lithium amalgams. The proposed mechanism is in agreement with the experimental data found in the literature.

  19. Evaluation of a novel PTFE material for separation and preconcentration of trace levels of metal ions in sequential injection (SI) and sequential injection lab-on-valve (SI-LOV) systems interfaced with detection by ETAAS

    DEFF Research Database (Denmark)

    Long, Xiangbao; Chomchoei, Roongrat; Gała, Piotr

    The operational characteristics of a novel PTFE bead material, granular Algoflon®, used for separation and preconcentration of metal ions via adsorption of on-line generated non-charged metal complexes, were evaluated in a sequential injection (SI) system furnished with an external packed column...... and in a sequential injection lab-on-valve (SI-LOV) system. Employed for the determination of cadmium(II), complexed with diethyldithiophosphate (DDPA), and detection by electrothermal atomic absorption spectrometry (ETAAS), its performance was compared to that of a previously used material, Aldrich PTFE, which had...... demonstrated that PTFE was the most promising for solid-state pretreatments. By comparing the two materials, the Algoflon® beads exhibited much higher sensitivity (1.6107 versus 0.2956 μg l-1 per integrated absorbance (s)), and better retention efficiency (82% versus 74%) and enrichment factor (20.8 versus 17...

  20. Grounding Damage to Conventional Vessels

    DEFF Research Database (Denmark)

    Lützen, Marie; Simonsen, Bo Cerup

    2003-01-01

    The present paper is concerned with rational design of conventional vessels with regard to bottom damage generated in grounding accidents. The aim of the work described here is to improve the design basis, primarily through analysis of new statistical data for grounding damage. The current regula...

  1. PLANNING VESSEL BODY SECTION PRODUCTION

    Directory of Open Access Journals (Sweden)

    A. G. Grivachevsky

    2015-01-01

    Full Text Available A problem of planning production of a vessel body section is considered. The problem is reduced to the classic Johnson’s tree-machine flow-shop scheduling problem. A genetic algorithm and computer experiment to compare efficiency of this algorithm and the algorithm of full enumeration are described.

  2. Pressure vessel and method therefor

    Science.gov (United States)

    Saunders, Timothy

    2017-09-05

    A pressure vessel includes a pump having a passage that extends between an inlet and an outlet. A duct at the pump outlet includes at least one dimension that is adjustable to facilitate forming a dynamic seal that limits backflow of gas through the passage.

  3. Commercial Passenger Fishing Vessel Fishery

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains the logbook data from U.S.A. Commercial Passenger Fishing Vessels (CPFV) fishing in the U.S.A. EEZ and in waters off of Baja California, from...

  4. Mercury-free dissolution of aluminum-clad fuel in nitric acid

    Science.gov (United States)

    Christian, Jerry D.; Anderson, Philip A.

    1994-01-01

    A mercury-free dissolution process for aluminum involves placing the aluminum in a dissolver vessel in contact with nitric acid-fluoboric acid mixture at an elevated temperature. By maintaining a continuous flow of the acid mixture through the dissolver vessel, an effluent containing aluminum nitrate, nitric acid, fluoboric acid and other dissolved components are removed.

  5. Development of PWR pressure vessel steels

    International Nuclear Information System (INIS)

    Druce, S.; Edwards, B.

    1982-01-01

    Requirements to be met by vessel steels for pressurized water reactors are analyzed. Chemicat composition of low-alloyed steels, mechanical properties of sheets and forgings made of these steels and changes in the composition and properties over the wall thickness of the reactor vessel are presented. Problems of the vessel manufacturing including welding and heat treatment processes of sheets and forgings are considered. Special attention is paid to steel embrittlement during vessel fabrication and operation (radiation embrittlement, thermal embrittlement). The role of non-metal inclusions and their effect on anisotropy of fracture toughness is discussed. Possible developments of vessel steels and procedures for producing reactor vessels are reviewed

  6. Development of PWR pressure vessel steels

    Energy Technology Data Exchange (ETDEWEB)

    Druce, S.; Edwards, B.

    1982-01-01

    Requirements to be met by vessel steels for pressurized water reactors are analyzed. Chemicat composition of low-alloyed steels, mechanical properties of sheets and forgings made of these steels and changes in the composition and properties over the wall thickness of the reactor vessel are presented. Problems of the vessel manufacturing including welding and heat treatment processes of sheets and forgings are considered. Special attention is paid to steel embrittlement during vessel fabrication and operation (radiation embrittlement, thermal embrittlement). The role of non-metal inclusions and their effect on anisotropy of fracture toughness is discussed. Possible developments of vessel steels and procedures for producing reactor vessels are reviewed.

  7. Pressure vessel for nuclear reactor plant consisting of several pre-stressed cast pressure vessels

    International Nuclear Information System (INIS)

    Bodmann, E.

    1984-01-01

    Several cylindrical pressure vessel components made of pressure castings are arranged on a sector of a circle around the cylindrical cast pressure vessel for accommodating the helium cooled HTR. Each component pressure vessel is connected to the reactor vessel by a horizontal gas duct. The contact surfaces between reactor and component pressure vessel are in one plane. In the spaces between the individual component pressure vessels, there are supporting blocks made of cast iron, which are hollow and also have flat surfaces. With the reactor vessel and the component pressure vessels they form a disc-shaped connecting part below and above the gas ducts. (orig./PW)

  8. 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.

  9. Microstructure and microwave dielectric properties of Na1/2Sm1/2TiO3 filled PTFE, an environmental friendly composites

    Science.gov (United States)

    Luo, Fuchuan; Tang, Bin; Yuan, Ying; Fang, Zixuan; Zhang, Shuren

    2018-04-01

    A study on Na1/2Sm1/2TiO3 filled and glassfiber reinforced polytetrafluoroethylene (PTFE) composites was described. The GF content was a fixed value of 4 wt%, and the NST content in the composite matrix changed from 26 to 66 wt%. The paper consisted of the manufactural process of the composite and the effects of filler content on the properties of the substrate, such as morphology, moisture absorption, density, dielectric properties and temperature coefficient of dielectric constant. As NST filler loading increased from 26 to 66 wt%, the dielectric constant and loss tangent experienced a continuously increase while the development in τε was opposite. X-Ray Diffraction, FTIR and XPS were used to analyze the microstructure of modified ceramic powder. It was proved that the silane coupling agent has been grafted on the NST surface successfully. At last, the NST/GF filled PTFE composites exhibited good dielectric constant (εr = 4.95), low dielectric loss (tan δ = 0.00147), acceptable water absorption (0.036) and temperature coefficient of dielectric constant (τε = -164) at filler loading of 4 wt% GF and 46 wt% NST.

  10. Calculation of Al2O3 contents in Al2O3-PTFE composite thick films fabricated by using the aerosol deposition

    International Nuclear Information System (INIS)

    Kim, Hyung-Jun; Kim, Yoon-Hyun; Nam, Song-Min; Yoon, Young-Joon; Kim, Jong-Hee

    2010-01-01

    Low-temperature fabrication of Al 2 O 3 -PTFE (poly tetra fluoro ethylene) composite thick films for flexible integrated substrates was attempted by using the aerosol deposition method. For optimization of composite thick films, a novel calculation method for the ceramic contents in the composites was attempted. Generally, a thermogravimetry (TG) analysis is used to calculate the ceramic contents in the ceramic-polymer composites. However, the TG analysis requires a long measurement time in each analysis, so we studied a novel calculation method that used a simple dielectric measurement. We used Hashin-Shtrikman bounds to obtain numerical results for the relationship between the dielectric constant of the composites and the contents of Al 2 O 3 . A 3-D electrostatic simulation model similar to the deposited Al 2 O 3 -PTFE composite thick films was prepared, and the simulation result was around the lower bound of the Hashin-Shtrikman bounds. As a result, we could calculate the Al 2 O 3 contents in the composites with a low error of below 5 vol.% from convenient dielectric measurements, and the Al 2 O 3 contents ranged from 51 vol.% to 54 vol.%.

  11. Tl response of LiF: Mg, Cu, P+Ptfe at X rays of 24, 42 and 100 KeV

    International Nuclear Information System (INIS)

    Gonzalez M, P.R.; Tovar M, V.M.; Azorin N, J.; Furetta, C.; Quiroz C, M.C.

    2005-01-01

    In this work the obtained results of the irradiation of thermoluminescent dosemeters (Tl) of LiF: Mg,Cu,P + Ptfe with X rays for the effective radiation energy of 24, 42 and 100 keV, in an interval of Kerma in air in the sinus of the air between 0.05 and 1.0 Gy are presented. The rate of Kerma in air was determined with an ionization chamber PTW-1152, gauged by the Laboratoire Central des Industries Electriques (LCIE). As reference commercial TLD-100 dosemeters was used. The results showed that the studied Tl dosemeters presented a lineal response in the interval of mentioned Kerma. On the other hand the estimated Kerma with the Tl dosemeter in the calibration curves for X rays, were similar to the one measured with the previously gauged ionization chamber. The Tl of LiF: Mg, Cu, P + Ptfe, developed in the ININ, are highly reliable for X-ray dosimetry. (Author)

  12. AFSC/FMA/Vessel Assessment Logging

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Vessels fishing trawl gear, vessels fishing hook-and-line and pot gear that are also greater than 57.5 feet overall, and shoreside and floating processing facilities...

  13. 2013 EPA Vessels General Permit (VGP)

    Data.gov (United States)

    U.S. Environmental Protection Agency — Information for any vessel that submitted a Notice of Intent (NOI), Notice of Termination (NOT), or annual report under EPA's 2013 Vessel General Permit (VGP)....

  14. Interstitial Cells of Blood Vessels

    Directory of Open Access Journals (Sweden)

    Vladimír Pucovský

    2010-01-01

    Full Text Available Blood vessels are made up of several distinct cell types. Although it was originally thought that the tunica media of blood vessels was composed of a homogeneous population of fully differentiated smooth muscle cells, more recent data suggest the existence of multiple smooth muscle cell subpopulations in the vascular wall. One of the cell types contributing to this heterogeneity is the novel, irregularly shaped, noncontractile cell with thin processes, termed interstitial cell, found in the tunica media of both veins and arteries. While the principal role of interstitial cells in veins seems to be pacemaking, the role of arterial interstitial cells is less clear. This review summarises the knowledge of the functional and structural properties of vascular interstitial cells accumulated so far, offers hypotheses on their physiological role, and proposes directions for future research.

  15. The Vessel Schedule Recovery Problem

    DEFF Research Database (Denmark)

    Brouer, Berit Dangaard; Plum, Christian Edinger Munk; Vaaben, Bo

    Maritime transportation is the backbone of world trade and is accountable for around 3% of the worlds CO2 emissions. We present the Vessel Schedule Recovery Problem (VSRP) to evaluate a given disruption scenario and to select a recovery action balancing the trade off between increased bunker cons...... consumption and the impact on the remaining network and the customer service level. The model is applied to 4 real cases from Maersk Line. Solutions are comparable or superior to those chosen by operations managers. Cost savings of up to 58% may be achieved.......Maritime transportation is the backbone of world trade and is accountable for around 3% of the worlds CO2 emissions. We present the Vessel Schedule Recovery Problem (VSRP) to evaluate a given disruption scenario and to select a recovery action balancing the trade off between increased bunker...

  16. Nuclear power plant pressure vessels. Inservice inspections

    International Nuclear Information System (INIS)

    1995-01-01

    The requirements for the planning and reporting of inservice inspections of nuclear power plant pressure vessels are presented. The guide specifically applies to inservice inspections of Safety class 1 and 2 nuclear power plant pressure vessels, piping, pumps and valves plus their supports and reactor pressure vessel internals by non- destructive examination methods (NDE). Inservice inspections according to the Pressure Vessel Degree (549/73) are discussed separately in the guide YVL 3.0. (4 refs.)

  17. Expanded Fermilab pressure vessel directory program

    Energy Technology Data Exchange (ETDEWEB)

    Tanner, A.

    1983-01-01

    Several procedures have been written to manage the information pertaining to the vacuum tanks and pressure vessels for which the laboratory is responsible. These procedures have been named TANK1 for the vessels belonging to the Accelerator Division, TANK2 and TANK3 for the vessels belonging to the Research Division and to Technical Support respectively, and TANK4 for the vessels belonging to the Business Division. The operating procedures are otherwise identical in every respect.

  18. Expanded Fermilab pressure vessel directory program

    International Nuclear Information System (INIS)

    Tanner, A.

    1983-01-01

    Several procedures have been written to manage the information pertaining to the vacuum tanks and pressure vessels for which the laboratory is responsible. These procedures have been named TANK1 for the vessels belonging to the Accelerator Division, TANK2 and TANK3 for the vessels belonging to the Research Division and to Technical Support respectively, and TANK4 for the vessels belonging to the Business Division. The operating procedures are otherwise identical in every respect

  19. Vacuum vessel for plasma devices

    International Nuclear Information System (INIS)

    Yamada, Masao; Taguchi, Masami.

    1975-01-01

    Object: To permit effective utility of the space in the inner and outer sides of the container wall and also permit repeated assembly for use. Structure: Vacuum vessel wall sections are sealed together by means of welding bellows, and also flange portions formed at the end of the wall sections are coupled together by bolts and are sealed together with a seal ring and a seal cap secured by welding. (Nakamura, S.)

  20. Reactor vessel head permanent shield

    International Nuclear Information System (INIS)

    Hankinson, M.F.; Leduc, R.J.; Richard, J.W.; Malandra, L.J.

    1989-01-01

    A nuclear reactor is described comprising: a nuclear reactor pressure vessel closure head; control rod drive mechanisms (CRDMs) disposed within the closure head so as to project vertically above the closure head; cooling air baffle means surrounding the control rod drive mechanisms for defining cooling air paths relative to the control rod drive mechanisms; means defined within the periphery of the closure head for accommodating fastening means for securing the closure head to its associated pressure vessel; lifting lugs fixedly secured to the closure head for facilitating lifting and lowering movements of the closure head relative to the pressure vessel; lift rods respectively operatively associated with the plurality of lifting lugs for transmitting load forces, developed during the lifting and lowering movements of the closure head, to the lifting lugs; upstanding radiation shield means interposed between the cooling air baffle means and the periphery of the enclosure head of shielding maintenance personnel operatively working upon the closure head fastening means from the effects of radiation which may emanate from the control rod drive mechanisms and the cooling air baffle means; and connecting systems respectively associated with each one of the lifting lugs and each one of the lifting rods for connecting each one of the lifting rods to a respective one of each one of the lifting lugs, and for simultaneously connecting a lower end portion of the upstanding radiation shield means to each one of the respective lifting lugs

  1. Reactor-vessel-sectioning demonstration

    International Nuclear Information System (INIS)

    Lundgren, R.A.

    1981-09-01

    A technical demonstration was successfully completed of simulated reactor vessel sectioning using the combined techniques of air arc gouging and flame cutting. A 4-ft x 3-ft x 9-in. thick sample was fabricated of A36 carbon steel to simulate a reactor vessel wall. A 1/4-in. layer of stainless steel (SS) was tungsten inert gas (TIG)-welded to the carbon steel. Several techniques were considered to section the simulated reactor vessel; air arc gouging was selected to penetrate the stainless steel, and flame cutting was selected to sever the carbon steel. Three sectioning operations were demonstrated. For all three, the operating parameters were the same; but the position of the sample was varied. For the first cut, the sample was placed in a horizontal position, and it was successfully severed from the SS side. For the second cut, the sample was turned over and cut from the carbon steel side. Cutting from the carbon steel side has the advantages of cost reduction

  2. 33 CFR 151.1512 - Vessel safety.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Vessel safety. 151.1512 Section... River § 151.1512 Vessel safety. Nothing in this subpart relieves the master of the responsibility for ensuring the safety and stability of the vessel or the safety of the crew and passengers, or any other...

  3. Reactor vessel supported by flexure member

    International Nuclear Information System (INIS)

    Crawford, J.D.; Pankow, B.

    1975-01-01

    A description is given of a reactor pressure vessel which is provided with vertical support means in the form of circumferentially spaced columns upon which the vessel is mounted. The columns are adapted to undergo flexure in order to accommodate the thermally induced displacements experienced by the vessel during operational transients

  4. 19 CFR 4.97 - Salvage vessels.

    Science.gov (United States)

    2010-04-01

    ... United States and Great Britain ‘concerning reciprocal rights for United States and Canada in the... meaning of this statute. (e) A Mexican vessel may engage in a salvage operation on a Mexican vessel in any territorial waters of the United States in which Mexican vessels are permitted to conduct such operations by...

  5. Model tests for prestressed concrete pressure vessels

    International Nuclear Information System (INIS)

    Stoever, R.

    1975-01-01

    Investigations with models of reactor pressure vessels are used to check results of three dimensional calculation methods and to predict the behaviour of the prototype. Model tests with 1:50 elastic pressure vessel models and with a 1:5 prestressed concrete pressure vessel are described and experimental results are presented. (orig.) [de

  6. 50 CFR 648.4 - Vessel permits.

    Science.gov (United States)

    2010-10-01

    ... carrying passengers for hire. (8) Atlantic bluefish vessels. (i) Commercial. Any vessel of the United... lands Atlantic bluefish in or from the EEZ in excess of the recreational possession limit specified at § 648.164 must have been issued and carry on board a valid commercial bluefish vessel permit. (ii) Party...

  7. Integrating Multiple Autonomous Underwater Vessels, Surface Vessels and Aircraft into Oceanographic Research Vessel Operations

    Science.gov (United States)

    McGillivary, P. A.; Borges de Sousa, J.; Martins, R.; Rajan, K.

    2012-12-01

    Autonomous platforms are increasingly used as components of Integrated Ocean Observing Systems and oceanographic research cruises. Systems deployed can include gliders or propeller-driven autonomous underwater vessels (AUVs), autonomous surface vessels (ASVs), and unmanned aircraft systems (UAS). Prior field campaigns have demonstrated successful communication, sensor data fusion and visualization for studies using gliders and AUVs. However, additional requirements exist for incorporating ASVs and UASs into ship operations. For these systems to be optimally integrated into research vessel data management and operational planning systems involves addressing three key issues: real-time field data availability, platform coordination, and data archiving for later analysis. A fleet of AUVs, ASVs and UAS deployed from a research vessel is best operated as a system integrated with the ship, provided communications among them can be sustained. For this purpose, Disruptive Tolerant Networking (DTN) software protocols for operation in communication-challenged environments help ensure reliable high-bandwidth communications. Additionally, system components need to have considerable onboard autonomy, namely adaptive sampling capabilities using their own onboard sensor data stream analysis. We discuss Oceanographic Decision Support System (ODSS) software currently used for situational awareness and planning onshore, and in the near future event detection and response will be coordinated among multiple vehicles. Results from recent field studies from oceanographic research vessels using AUVs, ASVs and UAS, including the Rapid Environmental Picture (REP-12) cruise, are presented describing methods and results for use of multi-vehicle communication and deliberative control networks, adaptive sampling with single and multiple platforms, issues relating to data management and archiving, and finally challenges that remain in addressing these technological issues. Significantly, the

  8. BRONZ KATKILI POLİ-TETRA-FLOR-ETİLEN (PTFE) KOMPOZİTLERİN PASLANMAZ ÇELİK MALZEMEYE KARŞI AŞINMA VE SÜRTÜNME DAVRANIŞLARI

    OpenAIRE

    Ünal, Hüseyin; Yetkin, Salih Hakan; Poyraz, Bayram

    2018-01-01

    Bu deneysel çalışmada, katkısızpoli-tetra-flor-etilen (PTFE) polimeri ile %25 bronz katkılı PTFE kompoziti ve%40 bronz katkılı PTFE kompozitlerin, kuru kayma şartları altında paslanmazçelik malzemeye karşı tribolojik performansları incelenmiştir. Tribolojiktestler, pim-disk aşınma cihazında ve oda sıcaklığında gerçekleştirilmiştir.Aşınma ve sürtünme testleri, 50N, 100N ve 150N yüklerde ve 1.0, 1.5 ve 2.0m/skayma hızlarında yapılmıştır. Aşınma test sonuçlarına göre, %40 bronz katkılıPTFE kompo...

  9. Sequential injection on-line matrix removal and trace metal preconcentration using a PTFE beads packed column as demonstrated for the determination of cadmium by electrothermal atomic absorption spectrometry

    DEFF Research Database (Denmark)

    Wang, Jianhua; Hansen, Elo Harald

    2002-01-01

    A sequential injection (SI) on-line matrix removal and trace metal preconcentration procedure by using a novel microcolumn packed with PTFE beads is described, and demonstrated for trace cadmium analysis with detection by electrothermal atomic absorption spectrometry (ETAAS). The analyte...

  10. Flaw distribution development from vessel ISI data

    International Nuclear Information System (INIS)

    Foulds, J.R.; Kennedy, E.L.; Basin, S.L.; Rosinski, S.T.

    1991-01-01

    Previous attempts to develop flaw distributions for use in the structural integrity evaluation of pressurized water reactor (PWR) vessels have aimed at the estimation of a ''generic'' distribution applicable to all vessels. In contrast, this paper describes the analysis of vessel-specific in-service inspection (ISI) data for the development of a flaw distribution reliably representative of the condition of the particular vessel inspected. The application of the methodology may be extended to other vessels, but has been primarily developed for PWR reactor vessels. For this study, the flaw data analyzed included data obtained from three recently performed PWR vessel ISIs and from laboratory inspection of selected weldment sections of the Midland reactor vessel. The variability in both the character of the reviewed data (size range of flaws, number of flaws) and the UT (ultrasonic test) inspection system performance identified a need for analyzing the inspection results on a vessel-, or data set-specific basis. For this purpose, traditional histogram-based methods were inadequate, and a new methodology that can accept a very small number of flaws (typical of vessel-specific ISI results) and that includes consideration of inspection system flaw detection reliability, flaw sizing accuracy and flaw detection threshold, was developed. Results of the application of the methodology to each of the four PWR reactor vessel cases studied are presented and discussed

  11. Primo vessel inside a lymph vessel emerging from a cancer tissue.

    Science.gov (United States)

    Lee, Sungwoo; Ryu, Yeonhee; Cha, Jinmyung; Lee, Jin-Kyu; Soh, Kwang-Sup; Kim, Sungchul; Lim, Jaekwan

    2012-10-01

    Primo vessels were observed inside the lymph vessels near the caudal vena cava of a rabbit and a rat and in the thoracic lymph duct of a mouse. In the current work we found a primo vessel inside the lymph vessel that came out from the tumor tissue of a mouse. A cancer model of a nude mouse was made with human lung cancer cell line NCI-H460. We injected fluorescent nanoparticles into the xenografted tumor tissue and studied their flow in blood, lymph, and primo vessels. Fluorescent nanoparticles flowed through the blood vessels quickly in few minutes, and but slowly in the lymph vessels. The bright fluorescent signals of nanoparticles disappeared within one hour in the blood vessels but remained much longer up to several hours in the case of lymph vessels. We found an exceptional case of lymph vessels that remained bright with fluorescence up to 24 hours. After detailed examination we found that the bright fluorescence was due to a putative primo vessel inside the lymph vessel. This rare observation is consistent with Bong-Han Kim's claim on the presence of a primo vascular system in lymph vessels. It provides a significant suggestion on the cancer metastasis through primo vessels and lymph vessels. Copyright © 2012. Published by Elsevier B.V.

  12. What is cerebral small vessel disease?

    International Nuclear Information System (INIS)

    Onodera, Osamu

    2011-01-01

    An accumulating amount of evidence suggests that the white matter hyperintensities on T 2 weighted brain magnetic resonance imaging predict an increased risk of dementia and gait disturbance. This state has been proposed as cerebral small vessel disease, including leukoaraiosis, Binswanger's disease, lacunar stroke and cerebral microbleeds. However, the concept of cerebral small vessel disease is still obscure. To understand the cerebral small vessel disease, the precise structure and function of cerebral small vessels must be clarified. Cerebral small vessels include several different arteries which have different anatomical structures and functions. Important functions of the cerebral small vessels are blood-brain barrier and perivasucular drainage of interstitial fluid from the brain parenchyma. Cerebral capillaries and glial endfeet, take an important role for these functions. However, the previous pathological investigations on cerebral small vessels have focused on larger arteries than capillaries. Therefore little is known about the pathology of capillaries in small vessel disease. The recent discoveries of genes which cause the cerebral small vessel disease indicate that the cerebral small vessel diseases are caused by a distinct molecular mechanism. One of the pathological findings in hereditary cerebral small vessel disease is the loss of smooth muscle cells, which is an also well-recognized finding in sporadic cerebral small vessel disease. Since pericytes have similar character with the smooth muscle cells, the pericytes should be investigated in these disorders. In addition, the loss of smooth muscle cells may result in dysfunction of drainage of interstitial fluid from capillaries. The precise correlation between the loss of smooth muscle cells and white matter disease is still unknown. However, the function that is specific to cerebral small vessel may be associated with the pathogenesis of cerebral small vessel disease. (author)

  13. 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

  14. Vacuum isostatic micro/macro molding of PTFE materials for laser beam shaping in environmental applications: large scale UV laser water purification

    Science.gov (United States)

    Lizotte, Todd; Ohar, Orest

    2009-08-01

    Accessibility to fresh clean water has determined the location and survival of civilizations throughout the ages [1]. The tangible economic value of water is demonstrated by industry's need for water in fields such as semiconductor, food and pharmaceutical manufacturing. Economic stability for all sectors of industry depends on access to reliable volumes of good quality water. As can be seen on television a nation's economy is seriously affected by water shortages through drought or mismanagement and as such those water resources must therefore be managed both for the public interest and the economic future. For over 50 years ultraviolet water purification has been the mainstay technology for water treatment, killing potential microbiological agents in water for leisure activities such as swimming pools to large scale waste water treatment facilities where the UV light photo-oxidizes various pollutants and contaminants. Well tailored to the task, UV provides a cost effective way to reduce the use of chemicals in sanitization and anti-biological applications. Predominantly based on low pressure Hg UV discharge lamps, the system is plagued with lifetime issues (~1 year normal operation), the last ten years has shown that the technology continues to advance and larger scale systems are turning to more advanced lamp designs and evaluating solidstate UV light sources and more powerful laser sources. One of the issues facing the treatment of water with UV lasers is an appropriate means of delivering laser light efficiently over larger volumes or cross sections of water. This paper examines the potential advantages of laser beam shaping components made from isostatically micro molding microstructured PTFE materials for integration into large scale water purification and sterilization systems, for both lamps and laser sources. Applying a unique patented fabrication method engineers can form micro and macro scale diffractive, holographic and faceted reflective structures

  15. 46 CFR 4.03-40 - Public vessels.

    Science.gov (United States)

    2010-10-01

    ... INVESTIGATIONS Definitions § 4.03-40 Public vessels. Public vessel means a vessel that— (a) Is owned, or demise... Department (except a vessel operated by the Coast Guard or Saint Lawrence Seaway Development Corporation...

  16. Progress of ITER vacuum vessel

    Energy Technology Data Exchange (ETDEWEB)

    Ioki, K., E-mail: Kimihiro.Ioki@iter.org [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-lez-Durance (France); Bayon, A. [F4E, c/ Josep Pla, No. 2, Torres Diagonal Litoral, Edificio B3, E-08019 Barcelona (Spain); Choi, C.H.; Daly, E.; Dani, S.; Davis, J.; Giraud, B.; Gribov, Y.; Hamlyn-Harris, C.; Jun, C.; Levesy, B. [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-lez-Durance (France); Kim, B.C. [NFRI, 52 Yeoeundong Yuseonggu, Daejeon 305-333 (Korea, Republic of); Kuzmin, E. [NTC “Sintez”, Efremov Inst., 189631 Metallostroy, St. Petersburg (Russian Federation); Le Barbier, R.; Martinez, J.-M. [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-lez-Durance (France); Pathak, H. [ITER-India, A-29, GIDC Electronic Estate, Sector 25, Gandhinagar 382025 (India); Preble, J. [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-lez-Durance (France); Sa, J.W. [NFRI, 52 Yeoeundong Yuseonggu, Daejeon 305-333 (Korea, Republic of); Terasawa, A.; Utin, Yu. [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-lez-Durance (France); and others

    2013-10-15

    Highlights: ► This covers the overall status and progress of the ITER vacuum vessel activities. ► It includes design, R and D, manufacturing and approval process of the regulators. ► The baseline design was completed and now manufacturing designs are on-going. ► R and D includes ISI, dynamic test of keys and lip-seal welding/cutting technology. ► The VV suppliers produced full-scale mock-ups and started VV manufacturing. -- Abstract: Design modifications were implemented in the vacuum vessel (VV) baseline design in 2011–2012 for finalization. The modifications are mostly due to interface components, such as support rails and feedthroughs for the in-vessel coils (IVC). Manufacturing designs are being developed at the domestic agencies (DAs) based on the baseline design. The VV support design was also finalized and tests on scale mock-ups are under preparation. Design of the in-wall shielding (IWS) has progressed, considering the assembly methods and the required tolerances. Further modifications are required to be consistent with the DAs’ manufacturing designs. Dynamic tests on the inter-modular and stub keys to support the blanket modules are being performed to measure the dynamic amplification factor (DAF). An in-service inspection (ISI) plan has been developed and R and D was launched for ISI. Conceptual design of the VV instrumentation has been developed. The VV baseline design was approved by the agreed notified body (ANB) in accordance with the French Nuclear Pressure Equipment Order procedure.

  17. Progress of ITER vacuum vessel

    International Nuclear Information System (INIS)

    Ioki, K.; Bayon, A.; Choi, C.H.; Daly, E.; Dani, S.; Davis, J.; Giraud, B.; Gribov, Y.; Hamlyn-Harris, C.; Jun, C.; Levesy, B.; Kim, B.C.; Kuzmin, E.; Le Barbier, R.; Martinez, J.-M.; Pathak, H.; Preble, J.; Sa, J.W.; Terasawa, A.; Utin, Yu.

    2013-01-01

    Highlights: ► This covers the overall status and progress of the ITER vacuum vessel activities. ► It includes design, R and D, manufacturing and approval process of the regulators. ► The baseline design was completed and now manufacturing designs are on-going. ► R and D includes ISI, dynamic test of keys and lip-seal welding/cutting technology. ► The VV suppliers produced full-scale mock-ups and started VV manufacturing. -- Abstract: Design modifications were implemented in the vacuum vessel (VV) baseline design in 2011–2012 for finalization. The modifications are mostly due to interface components, such as support rails and feedthroughs for the in-vessel coils (IVC). Manufacturing designs are being developed at the domestic agencies (DAs) based on the baseline design. The VV support design was also finalized and tests on scale mock-ups are under preparation. Design of the in-wall shielding (IWS) has progressed, considering the assembly methods and the required tolerances. Further modifications are required to be consistent with the DAs’ manufacturing designs. Dynamic tests on the inter-modular and stub keys to support the blanket modules are being performed to measure the dynamic amplification factor (DAF). An in-service inspection (ISI) plan has been developed and R and D was launched for ISI. Conceptual design of the VV instrumentation has been developed. The VV baseline design was approved by the agreed notified body (ANB) in accordance with the French Nuclear Pressure Equipment Order procedure

  18. Nuclear reactor pressure vessel flaw distribution development

    International Nuclear Information System (INIS)

    Kennedy, E.L.; Foulds, J.R.; Basin, S.L.

    1991-12-01

    Previous attempts to develop flaw distributions for probabilistic fracture mechanics analyses of pressurized water reactor (PWR) vessels have aimed at the estimation of a ''generic'' distribution applicable to all PWR vessels. In contrast, this report describes (1) a new flaw distribution development analytic methodology that can be applied to the analysis of vessel-specific inservice inspection (ISI) data, and (2) results of the application of the methodology to the analysis of flaw data for each vessel case (ISI data on three PWR vessels and laboratory inspection data on sections of the Midland reactor vessel). Results of this study show significant variation among the flaw distributions derived from the various data sets analyzed, strongly suggesting than a vessel-specific flaw distribution (for vessel integrity prediction under pressurized thermal shock) is preferred over a ''generic'' distribution. In addition, quantitative inspection system flaw sizing accuracy requirements have been identified for developing a flaw distribution from vessel ISI data. The new flaw data analysis methodology also permits quantifying the reliability of the flaw distribution estimate. Included in the report are identified needs for further development of several aspects of ISI data acquisition and vessel integrity prediction practice

  19. PRODUCTION OF TRIFLUOROACETIC ACID COMPOUNDS

    Science.gov (United States)

    Haworth, W.N.; Stacey, M.

    1949-08-30

    A process is described for the preparation of trifluoroacetic acid. Acetone vapor diluted wlth nitrogen and fluorine also diluted with nltrogen are fed separately at a temperature of about 210 deg C into a reaction vessel containing a catalyst mass selected from-the group consisting of silver and gold. The temperature in the reaction vessel is maintained in the range of 200 deg to 250 deg C. The reaction product, trifluoroacetyl fluoride, is absorbed in aqueous alkali solution. Trifluoroacetic acid is recovered from the solution by acidification wlth an acid such as sulfuric followed by steam distillation.

  20. 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)

  1. Regulation of Electrochemically Generated H2O2 in Situ from a Novel CB-PTFE Cathode for Transformation of Chlorine Benzene in Groundwater

    Science.gov (United States)

    Jiang, J.; Zhang, X.; Li, G.

    2014-12-01

    Fenton's reagents (H2O2 and Fe2+ catalyst commonly) have been widely used in soil and groundwater remediation. But the excessive H2O2 decomposition and the pH modification (acidification) problem have been limitations for Fenton based remediation strategies. The Electro-Fenton (E- Fenton) processes has been recently developed to solve the problems, in which Fe2+ or H2O2are generated in situ as continuing source of Fenton's reagents. In this study, a novel CB-PTFE cathode and a Fe cathode were employed to generate H2O2 and Fe2+ in situ simultaneously. The generated reactive oxidizing species, i.e., O2,H2O2 and hydroxyl radical (HO•), oxidized bio-refractory organics to nontoxic matters in groundwater. Automatic pH adjustments are achieved by appropriately arraying the electrodes. Laboratory batch tests and column tests for the E-Fenton oxidation and hybrid electrolysis system were conducted to evaluate the transformation efficiency of chlorine benzene. Results from batch experiments suggested the CB-PTFE cathode was effective for reducing O2 to H2O2. The H2O2 concentration reached 468 mg/L under the condition of pH 3.0 and 30mA/cm2 in 60 minutes, which was 5 and 10 times of that with a graphite and C-felt cathode. The removal efficiency of chlorine benzene reached 80% in 20 minutes. Both chlorine benzene degradation and H2O2 production increased with decreasing solution pH and increasing current density. The results from the columns tests proved that the in situ E-Fenton system is a feasible method for groundwater remediation.

  2. Assessment of Pain and Quality of Life in Lichtenstein Hernia Repair Using a New Monofilament PTFE Mesh: Comparison of Suture vs. Fibrin-Sealant Mesh Fixation.

    Science.gov (United States)

    Fortelny, René H; Petter-Puchner, Alexander H; Redl, Heinz; May, Christopher; Pospischil, Wolfgang; Glaser, Karl

    2014-01-01

    Inguinal hernia repair is one of the most common operations in general surgery. The Lichtenstein tension-free operation has become the gold standard in open inguinal hernia repair. Despite the low recurrence rates, pain and discomfort remain a problem for a large number of patients. The aim of this study was to compare suture fixation vs. fibrin sealing by using a new monofilament PTFE mesh, i.e., the Infinit(®) mesh by W. L. Gore & Associates. This study was designed as a controlled prospective single-center two-cohort study. A total of 38 patients were enrolled and operated in Lichtenstein technique either standard suture mesh fixation or fibrin-sealant mesh fixation were used as described in the TIMELI trial. Primary outcome parameters were postoperative complications with the new mesh (i.e., seroma, infection), pain, and quality of life evaluated by the VAS and the SF-36 questionnaire. Secondary outcome was recurrence assessed by ultrasound and physical examination. Follow-up time was 1 year. Significantly, less postoperative pain was reported in the fibrin-sealant group compared to the suture group at 6 weeks (P = 0.035), 6 months (P = 0.023), and 1 year (P = 0.011) postoperatively. Additionally, trends toward a higher postoperative quality of life, a faster surgical procedure, and a shorter hospital stay were seen in the fibrin-sealant group. Fibrin-sealant mesh fixation in Lichtenstein hernioplasty effectively reduces acute and chronic postoperative pain. Monofilament, macro-porous, knitted PTFE meshes seem to be a practicable alternative to commonly used polypropylene meshes in open inguinal hernia repair.

  3. Assessment of pain and quality of life in Lichtenstein hernia repair using a new monofilament PTFE mesh: comparison of suture vs. fibrin sealant mesh fixation

    Directory of Open Access Journals (Sweden)

    René H Fortelny

    2014-11-01

    Full Text Available Background: Inguinal hernia repair is one of the most common operations in general surgery. The Lichtenstein tension-free operation has become the gold standard in open inguinal hernia repair. Despite the low recurrence rates, pain and discomfort remain a problem for a large number of patients. The aim of this study was to compare suture fixation vs. fibrin sealing by using a new monofilament PTFE mesh, i.e. the Infinit® mesh by W. L. Gore & Associates. Methods: This study was designed as a controlled prospective single-centre two cohort study. A total of 38 patients were enrolled and operated in Lichtenstein technique either standard suture mesh fixation or fibrin sealant mesh fixation were used as described in the TIMELI trial. Primary outcome parameters were postoperative complications with the new mesh (i.e. seroma, infection, pain and quality of life evaluated by the VAS and the SF-36 questionnaire. Secondary outcome was recurrence assessed by ultrasound and physical examination. Follow-up time was 1 year.Results: Significantly less postoperative pain was reported in the fibrin sealant group compared to the suture group at 6 weeks (P=0.035, 6 months (P=0.023 and 1 year (P=0.011 postoperatively. Additionally trends towards a higher postoperative quality of life, a faster surgical procedure and a shorter hospital stay were seen in the fibrin sealant group.Conclusion: Fibrin sealant mesh fixation in Lichtenstein hernioplasty effectively reduces acute and chronic postoperative pain. Monofilament, macro-porous, knitted PTFE meshes seem to be a practicable alternative to commonly used polypropylene meshes in open inguinal hernia repair.

  4. Super-hydrophobic self-cleaning bead-like SiO2@PTFE nanofiber membranes for waterproof-breathable applications

    Science.gov (United States)

    Liang, Yueyao; Ju, Jingge; Deng, Nanping; Zhou, Xinghai; Yan, Jing; Kang, Weimin; Cheng, Bowen

    2018-06-01

    Superhydrophobic waterproof-breathable membranes, which possess a huge superiority in multi-functional applications including self-cleaning, anti-icing, anticorrosion and protective clothing, have aroused considerable attention owing to their excellent performance. Herein, the robust superhydrophobic microporous fibrous membranes were efficiently prepared via a facile and environmental-friendly electro-blown spinning (EBS) technique followed by calcination. Compared with hydrophobic pure PTFE fibrous membranes, the bead-like SiO2@PTFE nanofiber membranes (BLNFMs) exhibited superhydrophobic surface with the advancing water angle (θadv) and the water contact angle (WCA) up to 161° and 155°, respectively. The SiO2 nanoparticles were introduced as fillers which can alter the pore structure and form the multilevel rough surface. The BLNFMs could maintain superhydrophobic surface even after abrasion for 30 times or exposing to a strong corrosive solution with PH from 0 to 12 for 24 h. Besides, the BLNFMs were endowed with the modest vapor permeability (9.7 kg·m-2·d-1) and air permeability (7.2 mm·s-1) when the concentration of SiO2 nanoparticles reached to 7.3 wt%. In addition, a potential relationship among θadv, maximum pore size (dmax) and breathability (effective breathing area) was proposed in order to design the waterproof-breathable membranes with excellent properties. Furthermore, the superhydrophobic membranes with durable self-cleaning property provided the advantages of potential applications in the fields of membrane distillation, versatile protective clothing, etc.

  5. Hydrogen storage in insulated pressure vessels

    Energy Technology Data Exchange (ETDEWEB)

    Aceves, S.M.; Garcia-Villazana, O. [Lawrence Livermore National Lab., CA (United States)

    1998-08-01

    Insulated pressure vessels are cryogenic-capable pressure vessels that can be fueled with liquid hydrogen (LH{sub 2}) or ambient-temperature compressed hydrogen (CH{sub 2}). Insulated pressure vessels offer the advantages of liquid hydrogen tanks (low weight and volume), with reduced disadvantages (lower energy requirement for hydrogen liquefaction and reduced evaporative losses). This paper shows an evaluation of the applicability of the insulated pressure vessels for light-duty vehicles. The paper shows an evaluation of evaporative losses and insulation requirements and a description of the current analysis and experimental plans for testing insulated pressure vessels. The results show significant advantages to the use of insulated pressure vessels for light-duty vehicles.

  6. Neutron Assay System for Confinement Vessel Disposition

    International Nuclear Information System (INIS)

    Frame, Katherine C.; Bourne, Mark M.; Crooks, William J.; Evans, Louise; Mayo, Douglas R.; Miko, David K.; Salazar, William R.; Stange, Sy; Valdez, Jose I.; Vigil, Georgiana M.

    2012-01-01

    Los Alamos National Laboratory has a number of spherical confinement vessels (CVs) remaining from tests involving nuclear materials. These vessels have an inner diameter of 6 feet with 1-inch thick steel walls. The goal of the Confinement Vessel Disposition (CVD) project is to remove debris and reduce contamination inside the CVs. The Confinement Vessel Assay System (CVAS) was developed to measure the amount of special nuclear material (SNM) in CVs before and after cleanout. Prior to cleanout, the system will be used to perform a verification measurement of each vessel. After cleanout, the system will be used to perform safeguards-quality assays of (le)100-g 239 Pu equivalent in a vessel for safeguards termination. The CVAS has been tested and calibrated in preparation for verification and safeguards measurements.

  7. Automatic Vessel Segmentation on Retinal Images

    Institute of Scientific and Technical Information of China (English)

    Chun-Yuan Yu; Chia-Jen Chang; Yen-Ju Yao; Shyr-Shen Yu

    2014-01-01

    Several features of retinal vessels can be used to monitor the progression of diseases. Changes in vascular structures, for example, vessel caliber, branching angle, and tortuosity, are portents of many diseases such as diabetic retinopathy and arterial hyper-tension. This paper proposes an automatic retinal vessel segmentation method based on morphological closing and multi-scale line detection. First, an illumination correction is performed on the green band retinal image. Next, the morphological closing and subtraction processing are applied to obtain the crude retinal vessel image. Then, the multi-scale line detection is used to fine the vessel image. Finally, the binary vasculature is extracted by the Otsu algorithm. In this paper, for improving the drawbacks of multi-scale line detection, only the line detectors at 4 scales are used. The experimental results show that the accuracy is 0.939 for DRIVE (digital retinal images for vessel extraction) retinal database, which is much better than other methods.

  8. Electrical discharge machining for vessel sample removal

    International Nuclear Information System (INIS)

    Litka, T.J.

    1993-01-01

    Due to aging-related problems or essential metallurgy information (plant-life extension or decommissioning) of nuclear plants, sample removal from vessels may be required as part of an examination. Vessel or cladding samples with cracks may be removed to determine the cause of cracking. Vessel weld samples may be removed to determine the weld metallurgy. In all cases, an engineering analysis must be done prior to sample removal to determine the vessel's integrity upon sample removal. Electrical discharge machining (EDM) is being used for in-vessel nuclear power plant vessel sampling. Machining operations in reactor coolant system (RCS) components must be accomplished while collecting machining chips that could cause damage if they become part of the flow stream. The debris from EDM is a fine talclike particulate (no chips), which can be collected by flushing and filtration

  9. Exponential Stabilization of an Underactuated Surface Vessel

    Directory of Open Access Journals (Sweden)

    Kristin Y. Pettersen

    1997-07-01

    Full Text Available The paper shows that a large class of underactuated vehicles cannot be asymptotically stabilized by either continuous or discontinuous state feedback. Furthermore, stabilization of an underactuated surface vessel is considered. Controllability properties of the surface vessels is presented, and a continuous periodic time-varying feedback law is proposed. It is shown that this feedback law exponentially stabilizes the surface vessel to the origin, and this is illustrated by simulations.

  10. Computerized reactor pressure vessel materials information system

    International Nuclear Information System (INIS)

    Strosnider, J.; Monserrate, C.; Kenworthy, L.D.; Tether, C.D.

    1980-10-01

    A computerized information system for storage and retrieval of reactor pressure vessel materials data was established, as part of Task Action Plan A-11, Reactor Vessel Materials Toughness. Data stored in the system are necessary for evaluating the resistance of reactor pressure vessels to flaw-induced fracture. This report includes (1) a description of the information system; (2) guidance on accessing the system; and (3) a user's manual for the system

  11. How to replace a reactor pressure vessel

    International Nuclear Information System (INIS)

    Huber, R.

    1996-01-01

    A potential life extending procedure for a nuclear reactor after, say, 40 years of service life, might in some circumstances be the replacement of the reactor pressure vessel. Neutron induced degradation of the vessel might make replacement by one of a different material composition desirable, for example. Although the replacement of heavy components, such as steam generators, has been possible for many years, the pressure vessel presents a much more demanding task if only because it is highly irradiated. Some preliminary feasibility studies by Siemens are reported for the two removal strategies that might be considered. These are removal of the entire pressure vessel in one piece and dismantling it into sections. (UK)

  12. Prestressed reactor vessel for nuclear power plants

    International Nuclear Information System (INIS)

    Schoening, J.; Schwiers, H.G.

    1982-01-01

    With usual pressure vessels for nuclear reactor plants, especially for gas-cooled nuclear reactors, the load occurring due to the inner overpressure, especially the tensile load affecting the vessel top and/or bottom, their axis of inertia being horizontal, shall be compensated without a supplementary modification in design of the top and/or the bottom. This is attained by choosing an appropriate prestressing system of the vessel wall in the field the top and/or the bottom, so that the top and/or the bottom form a tension vault directed towards the interior of the vessel. (orig.) [de

  13. Reactor vessel decommissioning project. Final report

    International Nuclear Information System (INIS)

    Schoonen, D.H.

    1984-09-01

    This report describes a reactor vessel decommissioning project; it documents and explains the project objectives, scope, performance results, and sodium removal process. The project was successfully completed in FY-1983, within budget and without significant problems or adverse impact on the environment. Waste generated by the operation included the reactor vessel, drained sodium, and liquid, solid, and gaseous wastes which were significantly less than project estimates. Personnel radiation exposures were minimized, such that the project total was one-half the predicted exposure level. Except for the sodium removed, the material remaining in the reactor vessel is essentially the same as when the vessel arrived for processing

  14. Safety vessels for explosive fusion reactor

    International Nuclear Information System (INIS)

    Mineev, V.

    1994-01-01

    The failure of several types of geometrically similar cylindrical and spherical steel and glass fibers vessels filled with water or air was investigated when an explosive charge of TNT was detonated in the center. Vessels had radius 50-1000 mm, thickness of walls 2-20%. The detonation on TNT imitated energy release. The parameter: K = M/mf is a measure of the strength of the vessel where M is the mass of the vessel, and mf is the mass of TNT for which the vessel fails. This demanded 2-4 destroyed and nondestroyed shots. It may be showed that: K=A/σ f where σ f is the fracture stress of the material vessel, and A = const = F(energy TNT, characteristic of elasticity of vessel material). The chief results are the following: (1) A similar increase in the geometrical dimensions of steel vessels by a factor of 10 leads to the increase of parameter K in about 5 times and to decrease of failure deformation in 7 times (scale effect). (2) For glass fibers, scale effect is absent. (3) This problem is solved in terms of theory energetic scale effect. (4) The concept of TNT equivalent explosive makes it possible to use these investigations to evaluate the response of safety vessels for explosive fusion reactor

  15. Determinants of injuries in passenger vessel accidents.

    Science.gov (United States)

    Yip, Tsz Leung; Jin, Di; Talley, Wayne K

    2015-09-01

    This paper investigates determinants of crew and passenger injuries in passenger vessel accidents. Crew and passenger injury equations are estimated for ferry, ocean cruise, and river cruise vessel accidents, utilizing detailed data of individual vessel accidents that were investigated by the U.S. Coast Guard during the time period 2001-2008. The estimation results provide empirical evidence (for the first time in the literature) that crew injuries are determinants of passenger injuries in passenger vessel accidents. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Increase of cyclic durability of pressure vessels

    International Nuclear Information System (INIS)

    Vorona, V.A.; Zvezdin, Yu.I.

    1980-01-01

    The durability of multilayer pressure vessels under cyclic loading is compared with single-layer vessels. The relative conditional durability is calculated taking into account the assumption on the consequent destruction of layers and viewing a vessel wall as an indefinite plate. It is established that the durability is mainly determined by the number of layers and to a lesser degree depends on the relative size of the defect for the given layer thickness. The advantage of the multilayer vessels is the possibility of selecting layer materials so that to exclude the effect of agressive corrosion media on the strength [ru

  17. Vessel size measurements in angiograms: Manual measurements

    International Nuclear Information System (INIS)

    Hoffmann, Kenneth R.; Dmochowski, Jacek; Nazareth, Daryl P.; Miskolczi, Laszlo; Nemes, Balazs; Gopal, Anant; Wang Zhou; Rudin, Stephen; Bednarek, Daniel R.

    2003-01-01

    Vessel size measurement is perhaps the most often performed quantitative analysis in diagnostic and interventional angiography. Although automated vessel sizing techniques are generally considered to have good accuracy and precision, we have observed that clinicians rarely use these techniques in standard clinical practice, choosing to indicate the edges of vessels and catheters to determine sizes and calibrate magnifications, i.e., manual measurements. Thus, we undertook an investigation of the accuracy and precision of vessel sizes calculated from manually indicated edges of vessels. Manual measurements were performed by three neuroradiologists and three physicists. Vessel sizes ranged from 0.1-3.0 mm in simulation studies and 0.3-6.4 mm in phantom studies. Simulation resolution functions had full-widths-at-half-maximum (FWHM) ranging from 0.0 to 0.5 mm. Phantom studies were performed with 4.5 in., 6 in., 9 in., and 12 in. image intensifier modes, magnification factor = 1, with and without zooming. The accuracy and reproducibility of the measurements ranged from 0.1 to 0.2 mm, depending on vessel size, resolution, and pixel size, and zoom. These results indicate that manual measurements may have accuracies comparable to automated techniques for vessels with sizes greater than 1 mm, but that automated techniques which take into account the resolution function should be used for vessels with sizes smaller than 1 mm

  18. Vessels for elevated temperature service

    International Nuclear Information System (INIS)

    O'Donnell, W.J.; Porowski, J.S.

    1983-01-01

    The subject is covered in chapters, entitled: introduction (background; elevated temperature concerns; design tools); design of pressure vessels for elevated temperature per ASME code; basic elevated temperature failure modes; allowable stresses and strains per ASME code (basic allowable stress limits; ASME code limits for bending; time-fraction summations; strain limits; buckling and instability; negligible creep and stress-rupture effects); combined membrane and bending stresses in creep regime; thermal stress cycles; bounding methods based on elastic core concept (bounds on accumulated strains; more accurate bounds; strain ranges; maximum stresses; strains at discontinuities); elastic follow-up; creep strain concentrations; time-dependent fatigue (combined creep rupture and fatigue damage; limits for inelastic design analyses; limits for elastic design analyses); flaw evaluation techniques; type 316 stainless steel; type 304 stainless steel; steel 2 1/4Cr1Mo; Inconel 718; Incolloy 800; Hastelloy X; detailed inelastic design analyses. (U.K.)

  19. Milestones in pressure vessel technology

    International Nuclear Information System (INIS)

    Spence, J.; Nash, D.H.

    2004-01-01

    The progress of pressure vessel technology over the years has been influenced by many important events. This paper identifies a number of 'milestones' which have provided a stimulus to analysis methods, manufacturing, operational processes and new pressure equipment. The formation of a milestone itself along with its subsequent development is often critically dependent on the work of many individuals. It is postulated that such developments takes place in cycles, namely, an initial idea, followed sometimes by unexpected failures, which in turn stimulate analysis or investigation, and when confidence is established, followed finally by the emergence of codes ad standards. Starting from the industrial revolution, key milestones are traced through to the present day and beyond

  20. Tl response of LiF: Mg, Cu, P+Ptfe at X rays of 24, 42 and 100 KeV; Respuesta TL de LiF: Mg, Cu, P+Ptfe a rayos X de 24, 42 y 100 KeV

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez M, P.R.; Tovar M, V.M. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico); Azorin N, J. [UAM-I, 09340 Mexico D.F. (Mexico); Furetta, C. [Universita degli Studi di Roma ' La Sapienza' , Piazzale Aldo Moro 2, 00185 Roma (Italy); Quiroz C, M.C. [Facultad de Medicina, UAEM, 50180 Toluca, Estado de Mexico (Mexico)

    2005-07-01

    In this work the obtained results of the irradiation of thermoluminescent dosemeters (Tl) of LiF: Mg,Cu,P + Ptfe with X rays for the effective radiation energy of 24, 42 and 100 keV, in an interval of Kerma in air in the sinus of the air between 0.05 and 1.0 Gy are presented. The rate of Kerma in air was determined with an ionization chamber PTW-1152, gauged by the Laboratoire Central des Industries Electriques (LCIE). As reference commercial TLD-100 dosemeters was used. The results showed that the studied Tl dosemeters presented a lineal response in the interval of mentioned Kerma. On the other hand the estimated Kerma with the Tl dosemeter in the calibration curves for X rays, were similar to the one measured with the previously gauged ionization chamber. The Tl of LiF: Mg, Cu, P + Ptfe, developed in the ININ, are highly reliable for X-ray dosimetry. (Author)

  1. Reactor pressure vessel thermal annealing

    International Nuclear Information System (INIS)

    Lee, A.D.

    1997-01-01

    The steel plates and/or forgings and welds in the beltline region of a reactor pressure vessel (RPV) are subject to embrittlement from neutron irradiation. This embrittlement causes the fracture toughness of the beltline materials to be less than the fracture toughness of the unirradiated material. Material properties of RPVs that have been irradiated and embrittled are recoverable through thermal annealing of the vessel. The amount of recovery primarily depends on the level of the irradiation embrittlement, the chemical composition of the steel, and the annealing temperature and time. Since annealing is an option for extending the service lives of RPVs or establishing less restrictive pressure-temperature (P-T) limits; the industry, the Department of Energy (DOE) and the Nuclear Regulatory Commission (NRC) have assisted in efforts to determine the viability of thermal annealing for embrittlement recovery. General guidance for in-service annealing is provided in American Society for Testing and Materials (ASTM) Standard E 509-86. In addition, the American Society of Mechanical Engineers (ASME) Code Case N-557 addresses annealing conditions (temperature and duration), temperature monitoring, evaluation of loadings, and non-destructive examination techniques. The NRC thermal annealing rule (10 CFR 50.66) was approved by the Commission and published in the Federal Register on December 19, 1995. The Regulatory Guide on thermal annealing (RG 1.162) was processed in parallel with the rule package and was published on February 15, 1996. RG 1.162 contains a listing of issues that need to be addressed for thermal annealing of an RPV. The RG also provides alternatives for predicting re-embrittlement trends after the thermal anneal has been completed. This paper gives an overview of methodology and recent technical references that are associated with thermal annealing. Results from the DOE annealing prototype demonstration project, as well as NRC activities related to the

  2. Structural analysis of the KSTAR vacuum vessel

    Energy Technology Data Exchange (ETDEWEB)

    In, Sang Ryul; Yoon, Byeong Joo [Korea Atomic Energy Research Institute, Taejon (Korea)

    1998-10-01

    Structure analysis of the vacuum vessel for the KSTAR tokamak which, is in the end phase of the conceptual design have been performed. Mechanical stresses and deformations of the vessel produced by constant forces due to atmospheric pressure, dead weight, fluid pressure, etc and various transient electromagnetic forces induced during tokamak operations were calculated as well as modal characteristics and buckling properties were investigated. Influences of the temperature gradient and the constraint condition of the support on the thermal stress and deformation of the vessel were analyzed. The thermal stress due to the temperature distribution on the vessel as supplying the N{sub 2} gas of 400 deg C through poloidal channels according to the recent baking concept were calculated. No severe problem in the robustness of the vessel was found when applying the constant pressures on the vessel. However the mechanical stress due to the EM force induced by halo currents flowing on the vessel and the plasma facing components (PFCs) far exceeded the allowable limit. Some reinforcing components should be added on the boundary of the PFC support and the vessel, and that of the vessel support and the vessel. A steep temperature gradient in the vicinity of the inlet and oulet of the heating gas produced a thermal stress much higher than allowable. It is necessary to make the temperature of the vessel as uniform as possible and to develop a new support concept which is flexible enough to accommodate a thermal expansion of a few cm while sufficiently strong to resist mechanical impacts. (author). 5 refs., 41 figs., 9 tabs.

  3. A computational algorithm addressing how vessel length might depend on vessel diameter

    Science.gov (United States)

    Jing Cai; Shuoxin Zhang; Melvin T. Tyree

    2010-01-01

    The objective of this method paper was to examine a computational algorithm that may reveal how vessel length might depend on vessel diameter within any given stem or species. The computational method requires the assumption that vessels remain approximately constant in diameter over their entire length. When this method is applied to three species or hybrids in the...

  4. Vessel classification method based on vessel behavior in the port of Rotterdam

    NARCIS (Netherlands)

    Zhou, Y.; Daamen, W.; Vellinga, T.; Hoogendoorn, S.P.

    2015-01-01

    AIS (Automatic Identification System) data have proven to be a valuable source to investigate vessel behavior. The analysis of AIS data provides a possibility to recognize vessel behavior patterns in a waterway area. Furthermore, AIS data can be used to classify vessel behavior into several

  5. Nuclear reactor with a suspended vessel

    International Nuclear Information System (INIS)

    Lemercier, Guy.

    1977-01-01

    This invention relates to a nuclear reactor with a suspended vessel and applies in particular when this is a fast reactor, the core or active part of the reactor being inside the vessel and immersed under a suitable volume of flowing liquid metal to cool it by extracting the calories released by the nuclear fission in the fuel assemblies forming this core [fr

  6. Fabrication of Separator Demonstration Facility process vessel

    International Nuclear Information System (INIS)

    Oberst, E.F.

    1985-01-01

    The process vessel system is the central element in the Separator Development Facility (SDF). It houses the two major process components, i.e., the laser-beam folding optics and the separators pods. This major subsystem is the critical-path procurement for the SDF project. Details of the vaious parts of the process vessel are given

  7. Irradiation embrittlement of reactor vessel steels

    International Nuclear Information System (INIS)

    Bros, J.

    2000-01-01

    From the historical decision of closing the Yankee Rowe NPP because of the uncertainties on the level of reactor pressure vessel neutron embrittlement, this paper reviews the technical-scientist bases of the degradation phenomena, and refers to the evolution of reactor pressure vessel radiation surveillance programs. (Author)

  8. Ultrasound periodic inspections of reactor pressure vessels

    International Nuclear Information System (INIS)

    Haniger, L.

    1980-01-01

    Two versions are described of ultrasonic equipment for periodic inspections of reactor pressure vessels. One uses the principle of exchangeable programmators with solid-state logic while the other uses programmable logic with semiconductor memories. The equipment is to be used for inspections of welded joints on the upper part of the V-1 reactor pressure vessel. (L.O.)

  9. Elastic plastic buckling of elliptical vessel heads

    International Nuclear Information System (INIS)

    Alix, M.; Roche, R.L.

    1981-08-01

    The risks of buckling of dished vessel head increase when the vessel is thin walled. This paper gives the last results on experimental tests of 3 elliptical heads and compares all the results with some empirical formula dealing with elastic and plastic buckling

  10. Analyzing Vessel Behavior Using Process Mining

    NARCIS (Netherlands)

    Maggi, F.M.; Mooij, A.J.; Aalst, W.M.P. van der

    2013-01-01

    In the maritime domain, electronic sensors such as AIS receivers and radars collect large amounts of data about the vessels in a certain geographical area. We investigate the use of process mining techniques for analyzing the behavior of the vessels based on these data. In the context of maritime

  11. Nuclear reactor vessel fuel thermal insulating barrier

    Science.gov (United States)

    Keegan, C. Patrick; Scobel, James H.; Wright, Richard F.

    2013-03-19

    The reactor vessel of a nuclear reactor installation which is suspended from the cold leg nozzles in a reactor cavity is provided with a lower thermal insulating barrier spaced from the reactor vessel that has a hemispherical lower section that increases in volume from the center line of the reactor to the outer extent of the diameter of the thermal insulating barrier and smoothly transitions up the side walls of the vessel. The space between the thermal insulating harrier and the reactor vessel forms a chamber which can be flooded with cooling water through passive valving to directly cool the reactor vessel in the event of a severe accident. The passive inlet valve for the cooling water includes a buoyant door that is normally maintained sealed under its own weight and floats open when the cavity is Hooded. Passively opening steam vents are also provided.

  12. Method of burying vessel containing radioactive waste

    International Nuclear Information System (INIS)

    Koga, Yoshihito.

    1989-01-01

    A float having an inert gas sealed therein is attached to a tightly closed vessel containing radioactive wastes. The vessel is inserted and kept in a small hole for burying the tightly closed vessel in an excavated shaft in rocks such as of granite or rock salts, while filling bentonite as shielding material therearound. In this case, the float is so adjusted that the apparent specific gravity is made equal or nearer between the tightly closed vessel and the bentonite, so that the rightly closed vessel does not sink and cause direct contact with the rocks even if bentonite flows due to earthquakes, etc. This can prevent radioactivity contamination through water in the rocks. (S.K.)

  13. An experimental study on feasibility of ex-vessel cooling through the external guide vessel

    International Nuclear Information System (INIS)

    Kang, Kyoung-Ho; Kim, Jong-Hwan; Park, Rae-Jun; Kim, Sang-Baik

    2000-01-01

    This paper presents the results of a series of experiments for assessing the efficacy of ex-vessel cooling through the external guide vessel during a severe accident. Four tests were performed in the LAVA test facility at KAERI, varying the boundary conditions at the outer surface of the vessel. The first test was a dry condition test conducted without cooling the outside of the vessel. On the other hand, in the second test, the cooling of the vessel surface was produced by gravity-driven forced injection of water along the annular gap of 25 mm between the vessel and the external guide vessel. Water flow rate was about 0.85 kg/s and total mass of available water was 300 kg. For the evaluation of the water flow rate effect, the third test was performed with a pool type cooling in the annulus without any circulation of water. These two external cooling tests were performed under elevated pressure of about 1.6 MPa. Finally, the fourth test was conducted under atmospheric pressure to evaluate the effect of system pressure on boiling heat transfer characteristics. In the dry test and the pool type ex-vessel cooling test performed under atmospheric pressure, the vessel was failed by a melt penetration at about 40 degree upper position from the vessel bottom, which is coincident with the boundary of the Al 2 O 3 /Fe melt separated layers. On the other hand, in both of the ex-vessel cooling tests conducted under elevated pressure of about 1.6 MPa, the vessel didn't fail. Compared with the pool boiling test, the vessel experienced effective cooling due to the inlet flow in the forced flow test. Synthesized the results of the tests, it was shown that the heat removal with ex-vessel cooling through the guide vessel is feasible, but the additional evaluations should be performed to guarantee enough thermal margin. (author)

  14. Radiation embrittlement of PWR vessel supports

    International Nuclear Information System (INIS)

    Cheverton, R.D.; Robinson, G.C.; Pennell, W.E.; Nanstad, R.K.

    1989-01-01

    Several studies pertaining to radiation damage of PWR vessel supports were conducted between 1978 and 1987. During this period, apparently there was no reason to believe that low-temperature (<100 degree C) MTR embrittlement data were not appropriate for evaluating embrittlement of PWR vessel supports. However, late in 1986, data from the High Flux Isotope Reactor (HFIR) vessel surveillance program indicated that the embrittlement rates of the several HFIR vessel materials (A212-B, A350-LF3, A105-II) were substantially greater than anticipated on the basis of MTR data. Further evaluation of the HFIR data suggested that a fluence-rate effect was responsible for the apparent discrepancy, and shortly thereafter it became apparent that this rate effect was applicable to the evaluation of LWR vessel supports. As a result, the Nuclear Regulatory Commission (NRC) requested that the Oak Ridge National Laboratory (ORNL) evaluate the impact of the apparent embrittlement rate effect on the integrity of light-water-reactor (LWR) vessel supports. The purpose of the study was to provide an indication of whether the integrity of reactor vessel supports is likely to be challenged by radiation-induced embrittlement. The scope of the evaluation included correlation of the HFIR data for application to the evaluation of LWR vessel supports; a survey and cursory evaluation of all US LWR vessel support designs, selection of two plants for specific-plant evaluation, and a specific-plant evaluation of both plants to determine critical flaw sizes for their vessel supports. 19 refs., 8 figs., 2 tabs

  15. Thermal conductivity of a graphite bipolar plate (BPP) and its thermal contact resistance with fuel cell gas diffusion layers: Effect of compression, PTFE, micro porous layer (MPL), BPP out-of-flatness and cyclic load

    Science.gov (United States)

    Sadeghifar, Hamidreza; Djilali, Ned; Bahrami, Majid

    2015-01-01

    This paper reports on measurements of thermal conductivity of a graphite bipolar plate (BPP) as a function of temperature and its thermal contact resistance (TCR) with treated and untreated gas diffusion layers (GDLs). The thermal conductivity of the BPP decreases with temperature and its thermal contact resistance with GDLs, which has been overlooked in the literature, is found to be dominant over a relatively wide range of compression. The effects of PTFE loading, micro porous layer (MPL), compression, and BPP out-of-flatness are also investigated experimentally. It is found that high PTFE loadings, MPL and even small BPP out-of-flatness increase the BPP-GDL thermal contact resistance dramatically. The paper also presents the effect of cyclic load on the total resistance of a GDL-BPP assembly, which sheds light on the behavior of these materials under operating conditions in polymer electrolyte membrane fuel cells.

  16. ITER vacuum vessel, in vessel components and plasma facing materials

    International Nuclear Information System (INIS)

    Ioki, Kimihiro; Enoeda, M.; Federici, G.

    2007-01-01

    Design of the NB ports including duct liners under heat loads of the neutral beams has been developed. Design of the in-wall shielding has been developed in more details considering the supporting structure and the assembly method. The ferromagnetic inserts have previously not been installed in the outboard midplane region due to irregularity caused by the tangential ports for NB injection. Due to this configuration, the maximum ripple is relatively large (∝1 %) in a limited region of the plasma and the toroidal field flux lines fluctuate ∝10 mm in the FW region. To avoid these problems, additional ferromagnetic inserts are to be installed in the equatorial port region. Detailed studies were carried out on the ITER vacuum vessel to define appropriate codes and standards in the context of the ITER licensing in France. A set of draft documents regarding the ITER vacuum vessel structural code were prepared including an RCC-MR Addendum for the ITER VV with justified exceptions or modifications. The main deviation from the base Code is the extensive use of UT in lieu of radiography for the volumetric examination of all one-side access welds of the outer shell and field joint. The procurement allocation of blanket modules among 6 parties was fixed and the blanket module design has progressed in cooperation with parties. Fabrication of mock-ups for prequalification testing is under way and the tests will be performed in 2007-2008. Development of new beryllium materials is progressing in China and Russia. The ITER limiters will be installed in equatorial ports at two toroidal locations. The limiter plasma-facing surface protrudes ∝8 cm from the FW during the start-up and shutdown phase. In the new limiter concept, the limiters are retracted by ∝8 cm during the plasma flat top phase. This concept gives important advantages; (i) mitigation of the particle and heat loads due to disruptions, ELMs and blobs, (ii) improvement of the power coupling with the ICRH antenna

  17. Reactor pressure vessel. Status report

    International Nuclear Information System (INIS)

    Elliot, B.J.; Hackett, E.M.; Lee, A.D.

    1996-10-01

    This report describes the issues raised as a result of the staffs review of Generic Letter (GL) 92-01, Revision 1, responses and plant-specific reactor pressure vessel (RPV) assessments and the actions taken or work in progress to address these issues. In addition, the report describes actions taken by the staff and the nuclear industry to develop a thermal annealing process for use at U.S. commercial nuclear power plants. This process is intended to be used as a means of mitigating the effects of neutron radiation on the fracture toughness of RPV materials. The Nuclear Regulatory Commission (NRC) issued GL 92-01, Revision 1, Supplement 1, to obtain information needed to assess compliance with regulatory requirements and licensee commitments regarding RPV integrity. GL 92-01, Revision 1, Supplement 1, was issued as a result of generic issues that were raised in the NRC staff's reviews of licensee responses to GL 92-01, Revision 1, and plant-specific RPV evaluations. In particular, an integrated review of all data submitted in response to GL 92-01, Revision 1, indicated that licensees may not have considered all relevant data in their RPV assessments. This report is representative of submittals to and evaluations by the staff as of September 30, 1996. An update of this report will be issued at a later date

  18. In hydrofluoric acid corrosion-resistant materials

    International Nuclear Information System (INIS)

    Hauffe, K.

    1985-01-01

    Copper, red brass (Cu-15 Zn), special treated carbon steel and chromium-nickel-molybdenum steel represent materials of high resistivity against concentrated hydrofluoric acid ( 2 O 3 ) are employed for windows in the presence of hydrogen fluoride and/or hydrofluoric acid because of their superior optical properties and their excellent corrosion resistance. Polyethylen, polypropylene and polyvinyl chloride (PVC) belong to the cheapest corrosion resistant material for container and for coatings in the presence of hydrofluoric acid. Special polyester resins reinforced by glass or graphite fibers have been successfully employed as material for production units with hydrofluoric acid containing liquids up to 330 K. By carbon reinforced epoxy resin represents a corrosion resistant coating. Because of their excellent friction and corrosion resistance against concentrated hot hydrofluoric acid and HNO 3 -HF-solutions, PTFE and polyvinylidene fluoride are used as material for valves and axles in such environment. The expensive alloys, as for instance hastelloy and monel, are substituted more and more by fiber-reinfored polyolefins, PVC and fluorine containing polymers. (orig.) [de

  19. The chemistry of tributyl phosphate at elevated temperatures in the Plutonium Finishing Plant Process Vessels

    International Nuclear Information System (INIS)

    Barney, G.S.; Cooper, T.D.

    1994-01-01

    Potentially violent chemical reactions of the tributyl phosphate solvent used by the Plutonium Finishing Plant at the Hanford Site were investigated. There is a small probability that a significant quantity of this solvent could be accidental transferred to heated process vessels and react there with nitric acid or plutonium nitrate also present in the solvent extraction process. The results of laboratory studies of the reactions show that exothermic oxidation of tributyl phosphate by either nitric acid or actinide nitrates is slow at temperatures expected in the heated vessels. Less than four percent of the tributyl phosphate will be oxidized in these vented vessels at temperatures between 125 degrees C and 250 degrees C because the oxidant will be lost from the vessels by vaporization or decomposition before the tributyl phosphate can be extensively oxidized. The net amounts of heat generated by oxidation with concentrated nitric acid and with thorium nitrate (a stand-in for plutonium nitrate) were determined to be about -150 and -220 joules per gram of tributyl phosphate initially present, respectively. This is not enough heat to cause violent reactions in the vessels. Pyrolysis of the tributyl phosphate occurred in these mixtures at temperatures of 110 degrees C to 270 degrees C and produced mainly 1-butene gas, water, and pyrophosphoric acid. Butene gas generation is slow at expected process vessel temperatures, but the rate is faster at higher temperatures. At 252 degrees C the rate of butene gas generated was 0.33 g butene/min/g of tributyl phosphate present. The measured heat absorbed by the pyrolysis reaction was 228 J/g of tributyl phosphate initially present (or 14.5 kcal/mole of tributyl phosphate). Release of flammable butene gas into process areas where it could ignite appears to be the most serious safety consideration for the Plutonium Finishing Plant

  20. The chemistry of tributyl phosphate at elevated temperatures in the Plutonium Finishing Plant Process Vessels

    Energy Technology Data Exchange (ETDEWEB)

    Barney, G.S.; Cooper, T.D.

    1994-06-01

    Potentially violent chemical reactions of the tributyl phosphate solvent used by the Plutonium Finishing Plant at the Hanford Site were investigated. There is a small probability that a significant quantity of this solvent could be accidental transferred to heated process vessels and react there with nitric acid or plutonium nitrate also present in the solvent extraction process. The results of laboratory studies of the reactions show that exothermic oxidation of tributyl phosphate by either nitric acid or actinide nitrates is slow at temperatures expected in the heated vessels. Less than four percent of the tributyl phosphate will be oxidized in these vented vessels at temperatures between 125{degrees}C and 250{degrees}C because the oxidant will be lost from the vessels by vaporization or decomposition before the tributyl phosphate can be extensively oxidized. The net amounts of heat generated by oxidation with concentrated nitric acid and with thorium nitrate (a stand-in for plutonium nitrate) were determined to be about -150 and -220 joules per gram of tributyl phosphate initially present, respectively. This is not enough heat to cause violent reactions in the vessels. Pyrolysis of the tributyl phosphate occurred in these mixtures at temperatures of 110{degrees}C to 270{degrees}C and produced mainly 1-butene gas, water, and pyrophosphoric acid. Butene gas generation is slow at expected process vessel temperatures, but the rate is faster at higher temperatures. At 252{degrees}C the rate of butene gas generated was 0.33 g butene/min/g of tributyl phosphate present. The measured heat absorbed by the pyrolysis reaction was 228 J/g of tributyl phosphate initially present (or 14.5 kcal/mole of tributyl phosphate). Release of flammable butene gas into process areas where it could ignite appears to be the most serious safety consideration for the Plutonium Finishing Plant.