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Sample records for expanded polytetrafluoroethylene femoral-popliteal

  1. Expanded polytetrafluoroethylene augmentation of the lower face.

    PubMed

    Sherris, D A; Larrabee, W F

    1996-05-01

    Most options for rejuvenation of the lower face use soft-tissue fillers that augment the appropriate sites. Each of these options has associated risks and benefits. The U.S. Food and Drug Administration recently approved the use of expanded polytetrafluoroethylene (E-PTFE) as a soft-tissue filler in the face. From January 1991 through December 1993, the authors used E-PTFE soft-tissue patches for lower facial augmentation in 41 patients at 115 implant sites. Postsurgical follow-up has ranged from 2.5 to 4.5 years; during this time, complications have occurred in 4 patients. One implant had to be removed because of a seroma (1 patient), 4 implants required further secondary augmentation (2 patients), and 1 implant required revision because of malposition (1 patient). There have been no cases of implant infection, extrusion, long-term inflammation, or capsule formation. In this article, the authors review the technical aspects of E-PTFE use and discuss issues relating to the long-term efficacy of this new option for soft-tissue augmentation. The technique is also compared with other options for rejuvenation of the lower face. PMID:8628100

  2. Novel treatment techniques for recanalization of femoral-popliteal deep venous occlusion from chronic thrombosis.

    PubMed

    Spencer, Elizabeth Brooke; Stratil, Peter; Mizones, Heidi

    2014-06-01

    Patients with postthrombotic syndrome due to previous femoral-popliteal deep venous thrombosis often experience lifestyle-limiting lower-extremity pain and swelling. Conservative treatment options include compression stockings and lymphedema massage, but in many cases these treatments only temporarily and partially improve symptoms. Ultrasound and venography in patients with postthrombotic syndrome often show only partial recanalization of the femoral vein with significant collateral vein formation. These abnormal veins are insufficient for adequate venous drainage from the lower extremity as evidenced by the patient's continued symptoms. Recanalization of the occluded or partially occluded femoral vein using prolonged venoplasty, with or without chemical thrombolysis, combined with optimizing anticoagulation and conservative treatment measures, results in lasting improvement in symptoms for a high percentage of patients.

  3. The use of expanded polytetrafluoroethylene gloves for care of upper-extremity burns.

    PubMed

    Schiller, W R; Leukens, C; Neve, D

    1994-01-01

    The combination of a glove made of an expanded polytetrafluoroethylene membrane-based laminate and silver sulfadiazine cream was evaluated as a treatment for burned hands. Eight patients who had burns averaging 25% total body surface area and who had 11 extensive partial thickness hand burns (2% total body surface area) were treated with an average of 17 gloves over 9 days. The burn wounds healed with no unusual or unexpected outcomes. Nurses and therapists agreed that dressing changes were quick and easy and that the gloves provided greater range of motion and function in the hands. Patients also expressed a preference for this method of treatment.

  4. Antibacterial effects of the povidone-iodine vacuum impregnation technique in expanded polytetrafluoroethylene augmentation rhinoplasty.

    PubMed

    Lee, Jung Min; Lee, Joong Seob; Kim, Dong-Kyu; Lee, Jun Ho; Park, Hae Sang; Lee, Ho Jun; Bae, Sung Hee; Jang, Ji Su; Lee, Jae Jun; Park, Chan Hum

    2016-06-01

    Expanded polytetrafluoroethylene (e-PTFE) is a popular graft material for augmentation rhinoplasty. Gore-Tex and Surgiform are two types of e-PTFE; Surgiform has thicker fibrils and is more compact than Gore-Tex. We conducted an ex vivo study to evaluate the ability of povidone-iodine (PVP-I) vacuum pretreatment to prevent infection with these two types of e-PTFE. Gore-Tex and Surgiform specimens were cut into 2-mm(3) pieces, which were separated into two groups. One group for each e-PTFE was disinfected with vacuum PVP-I impregnation and the other group was not disinfected. Using the pieces of implant material, swabs were obtained from the nasal cavities of 20 healthy adults, and the specimens were incubated on agar plates and viewed by scanning electron microscopy (SEM). We found that PVP-I treatment significantly reduced the bacterial colony counts in both the Gore-Tex and Surgiform groups. In the SEM images, bacterial colonies were observed both inside and outside the untreated Gore-Tex; on the untreated Surgiform, they were found primarily on the surface. Few bacteria were detected in the PVP-I-treated Gore-Tex and Surgiform groups. Our findings suggest that PVP-I pretreatment can reduce the risk of infection associated with e-PTFE. PMID:27304448

  5. Modification of expanded polytetrafluoroethylene by UV irradiation in reactive and inert atmosphere

    NASA Astrophysics Data System (ADS)

    Gumpenberger, T.; Heitz, J.; Bäuerle, D.; Rosenmayer, T. C.

    2005-01-01

    The surface properties of expanded polytetrafluoroethylene (ePTFE) can be modified by 172 nm excimer lamp irradiation in ammonia (NH3) or acetylene (C2H2) atmosphere. This surface modification is either related to the substitution of fluorine by nitrogen- and/or hydrogen-containing groups or to the deposition of material from the gas phase. Additional oxygen-containing functionalities are incorporated by reactions with the residual gas and/or oxidation in air after treatment. The changes in surface properties are discussed on the basis of water contact-angle measurements, X-ray photoelectron spectroscopy (XPS) and IR spectroscopy on dense PTFE samples. Surface modification yields a reduction of the tear strength and break-down elongation in tensile tests. Field-emission scanning electron microscopy (FE-SEM) revealed that the tensile failure occurred at the contact of fibrils and nodes in the material. With 193 nm ArF excimer-laser irradiation in NH3 atmosphere, both the modification efficiency and material degradation are considerably lower.

  6. Results of Bony Chest Wall Reconstruction with Expanded Polytetrafluoroethylene Soft Tissue Patch

    PubMed Central

    Huang, Haibo; Kitano, Kentaro; Nagayama, Kazuhiro; Nitadori, Jun-ichi; Anraku, Masaki; Murakawa, Tomohiro

    2015-01-01

    Purpose: The early and long-term outcomes of bony chest wall reconstruction with expanded polytetrafluoroethylene (Gore-Tex) soft tissue patch remain a concern. No clinical study has reported the shrinkage of Gore-Tex following reconstruction to date. Methods: Thirty-seven patients who underwent bony chest wall reconstruction from 1994 to 2012 were retrospectively reviewed. Postoperative chest computed tomography images of 17 patients were examined, and shrinkage of reconstruction materials was measured and compared. Results: Gore-Tex was used for reconstruction in 18 patients, autologous materials were used in 14, Marlex mesh was used in four, and Medifit felt was used in one. No surgery-related deaths were observed. Twenty patients experienced early postoperative complications. Four patients experienced local infection. One patient with Marlex-mesh experienced empyema 33 days postoperatively. Chest drainage time in the Gore-Tex patients was significantly lower than in patients with other types of prosthetic reconstruction. No dislocation or dehiscence was found. Shrinkage of Gore-Tex was absent in 4 patients and acceptable in seven patients. No granulation formation was evident around the Gore-Tex, No significant difference in shrinkage was seen between the different materials used. Conclusion: Chest wall reconstruction with Gore-Tex was feasible with favorable early and long-term results. PMID:25641033

  7. Hyaluronic acid enhancement of expanded polytetrafluoroethylene for small diameter vascular grafts

    NASA Astrophysics Data System (ADS)

    Lewis, Nicole R.

    Cardiovascular disease is the leading cause of mortality and morbidity in the United States and other developed countries. In the United States alone, 8 million people are diagnosed with peripheral arterial disease per year and over 250,000 patients have coronary bypass surgery each year. Autologous blood vessels are the standard graft used in small diameter (<6mm) arterial bypass procedures. Synthetic small diameter grafts have had limited success. While polyethylene (Dacron) and expanded polytetrafluoroethylene (ePTFE) are the most commonly used small diameter synthetic vascular graft materials, there are significant limitations that make these materials unfavorable for use in the low blood flow conditions of the small diameter arteries. Specifically, Dacron and ePTFE grafts display failure due to early thrombosis or late intimal hyperplasia. With the shortage of tissue donors and the limited supply of autologous blood vessels available, there is a need for a small diameter synthetic vascular graft alternative. The aim of this research is to create and characterize ePTFE grafts prepared with hyaluronic acid (HA), evaluate thrombogenic potential of ePTFE-HA grafts, and evaluate graft mechanical properties and coating durability. The results in this work indicate the successful production of ePTFE-HA materials using a solvent infiltration technique. Surface interactions with blood show increased platelet adhesion on HA-modified surfaces, though evidence may suggest less platelet activation and erythrocyte lysis. Significant changes in mechanical properties of HA-modified ePTFE materials were observed. Further investigation into solvent selection, uniformity of HA, endothelialization, and dynamic flow testing would be beneficial in the evaluation of these materials for use in small diameter vascular graft bypass procedures.

  8. Ultrasound-induced thermal therapy of hyperplasia in ringed expanded polytetrafluoroethylene (eptfe) access grafts

    NASA Astrophysics Data System (ADS)

    Query, Michael Earl

    Hemodialysis vascular access, the interface between a dialysis patient and a dialysis machine, is quite literally the lifeblood of a patient's health. Vascular access dysfunction is the leading cause of hospitalization in hemodialysis patients. The occlusive growth of neointimal hyperplasia (NH) in expanded polytetrafluoroethylene (ePTFE) ringed grafts is the primary cause of failure. To further develop a proposed thermal ultrasound treatment to reduce or prevent NH in arteriovenous vascular grafts, the acoustic properties of ePTFE were studied in water and alcohol solutions. Previous reports of ePTFE acoustic properties are critiqued. It was found that the acoustic transmission and attenuation through ePTFE, and therefore the potential for an ultrasound-based therapy for NH, are heavily dependent on the medium in which the graft is immersed, suggesting that the acoustic properties of implanted grafts will change as grafts mature in vivo. The acoustic impedance and attenuation of water-soaked ePTFE were 0.478 +/- 1.43 x 10-2 MRayl and 1.78 +/- 0.111 Np/cm*MHz, respectively, while the acoustic impedance and attenuation of ePTFE in alcohol were 1.49 +/- 0.149 MRayl and 0.77 +/- 1.1 x 10-2 Np/cm*MHz, respectively. The use of focused ultrasound to heat implanted ringed ePTFE grafts was numerically modeled from 1.35- and 1.443-MHz transducers for in vitro geometries. Power deposition and heating, in turn, differed by an order of magnitude between various graft acoustic properties. Graft rings were predicted to be substantial absorbing and scattering features. In vitro phantom models were constructed: one with and one without thermocouples. At 1 W of acoustic power, the maximum temperature rise was 8˚ C. The thermocouple model containing a water-soaked graft did not experience heating in the far graft wall. The MRTI model confirmed that the graft rings are an absorbing/scattering feature. Heating was not prevented in the presence of water flow through the graft. Water

  9. Improved biomechanical resistance using an expanded polytetrafluoroethylene composite-structure prosthesis.

    PubMed

    Bellón, Juan M; Rodríguez, Marta; Serrano, Natalia; San-Martín, Antonio Carrera; Buján, Julia

    2004-05-01

    We designed a composite-structure (laminar-reticular) prosthesis using expanded polytetrafluoroethylene (ePTFE) as the biomaterial in an attempt to improve the biomechanical resistance of the same biomaterial in the form of a single lamina. Defects (7 x 5 cm) were created in the abdominal wall of male white New Zealand rabbits (n = 24). The defects, which comprised all the wall layers except the skin, were then repaired with one of two types of ePTFE prosthesis. One was a latest generation laminar prosthesis (DualMesh, or Gore-Tex) and the other was a composite of in-house design (CV-4 mesh composite) made by suturing a mesh woven out of ePTFE thread to an ePTFE lamina. After sacrificing the animals at 14 or 90 days after surgery, implant specimens were subjected to morphologic analysis (light microscopy and scanning electron microscopy); and adhesion formation, neoperitoneal thickness, and biomechanical strength were evaluated. No significant differences were recorded between the two prosthesis regarding the consistency of adhesions or the area occupied by adhesions (DM 0.17 +/- 0.06; CV-4 mesh composite 0.18 +/- 0.08 cm2) (p > 0.05). Notably, improved tissue integration was achieved using the composite prosthesis; its reticular side became infiltrated by dense connective tissue that enveloped the mesh filaments. In contrast, the DM prosthesis became encapsulated by host tissue. The neoperitoneum induced by both prostheses was homogeneous and orderly, with a layer of typical mesothelial cells lining its inner surface. The thickness of the neoperitoneum was similar (p > 0.05) for the two implants (385.0 +/- 3.4 vs. 390 +/- 3.1 microm), although significantly higher (p < 0.05) mechanical resistance values were recorded for the composite prosthesis (26.75 +/- 3.71 vs. 14.11 +/- 3.71 N). Our findings suggest that the use of a reticular and a laminar ePTFE layer in the same prosthesis leads to better repair and biomechanical behavior compared to the use of a single

  10. Surface zwitterionization of expanded poly(tetrafluoroethylene) membranes via atmospheric plasma-induced polymerization for enhanced skin wound healing.

    PubMed

    Jhong, Jheng-Fong; Venault, Antoine; Hou, Chun-Chung; Chen, Sheng-Han; Wei, Ta-Chin; Zheng, Jie; Huang, James; Chang, Yung

    2013-07-24

    Development of bioinert membranes to prevent blood clotting, tissue adhesion, and bacterial attachment is important for the wound healing process. In this work, two wound-contacting membranes of expanded poly(tetrafluoroethylene) (ePTFE) grafted with zwitterionic poly(sulfobetaine methacrylate) (PSBMA) and hydrophilic poly(ethylene glycol) methacrylate (PEGMA) via atmospheric plasma-induced surface copolymerization were studied. The surface grafting chemical structure, hydrophilicity, and hydration capability of the membranes were determined to illustrate the correlations between bioadhesive properties and wound recovery of PEGylated and zwitterionic ePTFE membranes. Bioadhesive properties of the membranes were evaluated by the plasma protein adsorption, platelet activation, blood cell hemolysis, tissue cell adhesion, and bacterial attachment. It was found that the zwitterionic PSBMA-grafted ePTFE membrane presented high hydration capability and exhibited the best nonbioadhesive character in contact with protein solution, human blood, tissue cells, and bacterial medium. This work shows that zwitterionic membrane dressing provides a moist environment, essential for "deep" skin wound healing observed from the animal rat model in vivo and permits a complete recovery after 14 days, with histology of repaired skin similar to that of normal skin tissue. This work suggests that the bioinert nature of grafted PSBMA polymers obtained by controlling grafting structures gives them great potential in the molecular design of antibioadhesive membranes for use in skin tissue regeneration. PMID:23795955

  11. Reduced platelet deposition on seeded versus unseeded segments of expanded polytetrafluoroethylene grafts: Clinical observations after a 6-month follow-up

    SciTech Connect

    Ortenwall, P.; Wadenvik, H.; Risberg, B. )

    1989-10-01

    The concept of autologous endothelial cell seeding has proved successful in animal models with respect to decrease of graft thrombogenicity and increase in patency. In the present study, application of this method in humans was explored. In 23 patients, random halves of expanded polytetrafluoroethylene grafts, used for lower limb arterial reconstructions, were seeded with endothelial cells at a seeding density of 3500 cells/cm{sup 2}. These cells were derived from the saphenous vein by enzymatic harvesting. The other half was sham seeded with culture medium. Graft thrombogenicity was estimated by measuring platelet deposition on graft surface 1 and 6 months after surgery, with indium 111-labeled platelets and external gamma-camera imaging. Seeded graft segments accumulated significantly (p less than 0.03) fewer platelets at all imaging times. It is concluded that seeding of expanded polytetrafluoroethylene vascular grafts in humans reduces graft surface thrombogenicity. The clinical implications of this remain to be demonstrated.

  12. Thermal treatment of expanded polytetraflu-oroethylene (ePTFE) membranes for reconstruction of a valved conduit.

    PubMed

    Zhu, Guangyu; Yuan, Qi; Hock Yeo, Joon; Nakao, Masakazu

    2015-01-01

    The unique micro porous structure of expanded polytetrafluoroethylene (ePTFE) that allows bio-integration for fixation, as well as overall mechanical integrity make it used successfully in a number of biomedical and clinical applications, which include the reconstruction of the pulmonary valve in in right ventricular outflow tract reconstruction (RVOT) operations. The objective of this study was to determine the effects of the thermal treatment on physical and mechanical properties of ePTFE membranes. ePTFE sheets were cut into 16 rectangle strips (10 mm by 60 mm) and evenly separated into 4 groups. One group was the blank control (group A), while the rest of the three groups (group B to D) were heated to 350°C and cooled to 24°C at different cooling rates (10°C/min, 20°C/min and rapid ambient air cooling) in a temperature controlled atmosphere. The mechanical and morphological characteristics of all the samples were tested using a tensile test machine and a scanning electron microscopy (SEM). The results show that the elastic modulus of group B to D was 24.95%, 33.45% and 72.76% higher than group A. The percentage elongation of groups B to D was found to be between 2.3% and 40.45% lower than group A. The proportion of pores in the ePTFE membrane was reduced following the thermal treatment. There were no morphology differences observed between groups B to D. In summary, the selection of cooling rate was important for preserving the mechanical properties of ePTFE membranes under thermal treatment. These findings may provide useful information for the preparation of molded ePTFE valve in RVOT operations. PMID:26406048

  13. Expanded polytetrafluoroethylene and dental rubber dam barrier membranes in the treatment of periodontal intrabony defects. A comparative clinical trial.

    PubMed

    Paolantonio, M; D'Archivio, D; Di Placido, G; Tumini, V; Di Peppe, G; Del Giglio Matarazzo, A; De Luca, M

    1998-11-01

    As observed in previous case reports, dental rubber dam (DRD) can be utilized as a barrier membrane in the guided tissue regeneration (GTR) technique for the treatment of periodontal intrabony defects. The purpose of the present study was (1) to confirm the validity of DRD as a suitable material in regenerative procedures and (2) to compare, in a split-mouth clinical trial, the effectiveness of DRD-made membranes in the treatment of periodontal intrabony defects versus that of expanded polytetrafluoroethylene (e-PTFE) barriers. 22 systemically healthy non-smoker adult periodontitis patients (7 male, 15 female) aged between 35 to 58 years were selected for the study. In each patient, a couple of 2-3 wall intrabony defects, located in different quadrants, were treated by a GTR technique using DRD (test sites) and e-PTFE (control sites), respectively. Performing a strict control of the oral hygiene level and of the marginal gingival health during the whole period of study, clinical (pocket probing depth, PPD; probing attachment level, PAL; gingival recession, GR) and intrasurgical (depth of the defect's intraosseous component, IOC; level of the alveolar crest, ACL) parameters were recorded at baseline and at the 1-year re-entry procedure in each experimental site. Furthermore, the coronal level of the newly formed tissue from the base of the defect (NFTL) and the vertical bone gain (VBG) were calculated at the time of membrane removal and after the re-entry procedure respectively. Membranes were removed from both test and control sites after 5 weeks; however, exposure of the membrane always occurred in test sites whereas it was observed in only 6 out of 22 control sites, this fact leading to an incomplete coverage of the regenerated tissue by the gingival flap in 18 out of 22 test sites. In both test and control sites, a statistically significant improvement of clinical and intrasurgical parameters occurred at the end of the study period; however, a significantly

  14. Use of the Viatorr Expanded Polytetrafluoroethylene-Covered Stent-Graft for Transjugular Intrahepatic Portosystemic Shunt Creation in Children: Initial Clinical Experience

    SciTech Connect

    Mermuys, Koen; Maleux, Geert Heye, Sam; Lombaerts, Rita; Nevens, Frederik

    2008-07-15

    Four children, three boys and one girl, with a median age of 9 years 8 months, underwent transjugular intrahepatic portosystemic shunt creation with an expanded polytetrafluoroethylene (e-PTFE)-covered nitinol stent. The stent-graft was successfully placed in all four patients without any complication. Clinical and biochemical improvement was noted in all four patients during follow-up. Radiological follow-up with use of duplex ultrasound showed a recurrent stenosis of the shunt 180 days after stent-graft implantation in one patient. This was treated with placement of an additional stent-graft, re-expanding completely the recurrent stenosis. In the other three patients, the stent-graft remained fully patent until the end of the study or until orthotopic liver transplantation. These preliminary results suggest that use of the Viatorr ePTFE-covered stent-graft in children is safe and feasible, with potentially the same high patency rate and improved clinical outcome as reported in adult patients.

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

    SciTech Connect

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

    2011-02-15

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

  16. Comparison of Small-Intestinal Submucosa and Expanded Polytetrafluoroethylene as a Vascular Conduit in the Presence of Gram-Positive Contamination

    PubMed Central

    Shell, Daniel H.; Croce, Martin A.; Cagiannos, Catherine; Jernigan, T Wright; Edwards, Norma; Fabian, Timothy C.

    2005-01-01

    Objective: As a vascular conduit, expanded polytetrafluoroethylene (ePTFE) is susceptible to graft infection with Gram-positive organisms. Biomaterials, such as porcine small-intestinal submucosa (SIS), have been successfully used clinically as tissue substitutes outside the vascular arena. Summary Background Data: In the present study, we compared a small-diameter conduit of SIS to ePTFE in the presence of Gram-positive contamination to evaluate infection resistance, incorporation and remodeling, morphometry, graft patency, and neointimal hyperplasia (NH) development. Methods: Adult male mongrel pigs were randomized to receive either SIS or ePTFE (3-cm length, 6-mm diameter) and further randomized to 1 of 3 groups: Control (no graft inoculation), Staphylococcus aureus, or mucin-producing S epidermidis (each graft inoculation with 108 colonies/mL). Pressure measurements were obtained proximal and distal to the graft to create the iliac/aorta pressure ratio. Morphometric analysis of the neointima and histopathologic examinations was performed. Other outcomes included weekly WBC counts, graft incorporation, and quantitative culture of explanted grafts. Results: Eighteen animals were randomized. All grafts were patent throughout the 6-week study period. Infected SIS grafts had less NH and little change in their iliac/aorta indices compared with infected ePTFE grafts. Quantitative cultures at euthanasia demonstrated no growth in either SIS group compared with 1.7 × 104 colonies for ePTFE S aureus and 6 × 102 for ePTFE S epi (each P < 0.001). All SIS grafts were incorporated. Histology demonstrated remodeling into host artery with smooth muscle and capillary ingrowth in all SIS groups. Scanning electron micrography illustrated smooth and complete endothelialization of all SIS grafts. Conclusions: Compared with ePTFE, SIS induces host tissue remodeling, exhibits a decreased neointimal response to infection, and is resistant to bacterial colonization. SIS may provide a

  17. Polytetrafluoroethylene sponge syringosubarachnoid shunt.

    PubMed

    Chagla, Aadil S; Kansal, Ritesh; Srikant, Balasubramaniam

    2011-01-01

    Syringomyelia is condition in which a cyst or cavity forms inside the spinal cavity. Its management always remains a difficult. A variety of surgical techniques have been used in management of syringomyelia. Syringosubarachnoid shunt remains an effective method in management of syringomyelia. Shunt tube obstruction remains an important complication of shunt procedure. We describe a novel technique of use of polytetrafluoroethylene sponge shunt for syringosubarachnoid shunt in patient with large syrinx and Chiari 1 malformation. Polytetrafluoroethylene sponge is a non irritant material with multiple porosities that is less susceptible to blockages or kinking. It could provide a good alternative technique in syringosubarachnoid shunting.

  18. Equation of state of polytetrafluoroethylene

    NASA Astrophysics Data System (ADS)

    Bourne, N. K.; Gray, G. T.

    2003-06-01

    The present drive to make munitions as safe as is feasible and to develop predictive models describing their constitutive response, has led to the development and production of plastic bonded explosives and propellants. There is a range of elastomers used as binder materials with the energetic components. One of these is known as Kel-F-800™ (poly-chloro-trifluroethylene) whose structure is in some ways analogous to that of poly-tetrafluoroethylene (PTFE or Teflon). Thus, it is of interest to assess the mechanical behavior of Teflon and to compare the response of five different production Teflon materials, two of which were produced in pedigree form, one as-received product, and two from previous in-depth literature studies. The equations of state of these variants were quantified by conducting a series of shock impact experiments in which both pressure-particle velocity and shock velocity-particle velocity dependencies were measured. The compressive behavior of Teflon, based upon the results of this study, appears to be independent of the production route and additives introduced.

  19. 75 FR 67105 - Granular Polytetrafluoroethylene Resin From Italy and Japan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-01

    ... granular polytetrafluoroethylene resin from Japan (53 FR 32267). On August 30, 1988, Commerce issued an antidumping duty order on imports of granular polytetrafluoroethylene resin from Italy (53 FR 33163... orders on imports of granular polytetrafluoroethylene resin from Italy and Japan (70 FR 76026)....

  20. 76 FR 39896 - Granular Polytetrafluoroethylene Resin From Italy

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-07

    ... COMMISSION Granular Polytetrafluoroethylene Resin From Italy Determination On the basis of the record \\1... antidumping duty order on granular polytetrafluoroethylene resin from Italy would be likely to lead to... Granular Polytetrafluoroethylene Resin from Italy: Investigation No. 731-TA-385 (Third Review). By order...

  1. 21 CFR 878.5035 - Nonabsorbable expanded polytetrafluoroethylene surgical suture.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical..., including cardiovascular surgery. It may be undyed or dyed with an approved color additive and may...

  2. 21 CFR 878.5035 - Nonabsorbable expanded polytetrafluoroethylene surgical suture.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical..., including cardiovascular surgery. It may be undyed or dyed with an approved color additive and may...

  3. 21 CFR 878.5035 - Nonabsorbable expanded polytetrafluoroethylene surgical suture.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical..., including cardiovascular surgery. It may be undyed or dyed with an approved color additive and may...

  4. 21 CFR 878.5035 - Nonabsorbable expanded polytetrafluoroethylene surgical suture.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical..., including cardiovascular surgery. It may be undyed or dyed with an approved color additive and may...

  5. 21 CFR 878.5035 - Nonabsorbable expanded polytetrafluoroethylene surgical suture.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical..., including cardiovascular surgery. It may be undyed or dyed with an approved color additive and may...

  6. 21 CFR 878.4520 - Polytetrafluoroethylene injectable.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Polytetrafluoroethylene injectable. 878.4520 Section 878.4520 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices §...

  7. 21 CFR 878.4520 - Polytetrafluoroethylene injectable.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Polytetrafluoroethylene injectable. 878.4520 Section 878.4520 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices §...

  8. 21 CFR 878.4520 - Polytetrafluoroethylene injectable.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Polytetrafluoroethylene injectable. 878.4520 Section 878.4520 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices §...

  9. 21 CFR 878.4520 - Polytetrafluoroethylene injectable.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Polytetrafluoroethylene injectable. 878.4520 Section 878.4520 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices §...

  10. 21 CFR 878.4520 - Polytetrafluoroethylene injectable.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Polytetrafluoroethylene injectable. 878.4520 Section 878.4520 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices §...

  11. 76 FR 42114 - Granular Polytetrafluoroethylene Resin From Italy: Continuation of Antidumping Duty Order

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-18

    ... Granular Polytetrafluoroethylene Resin From Italy, 76 FR 39896 (July 7, 2011), and USITC Publication 4240... International Trade Administration Granular Polytetrafluoroethylene Resin From Italy: Continuation of... the antidumping duty order on granular polytetrafluoroethylene resin (``PTFE resin'') from Italy...

  12. Toxicity of pyrolysis gases from polytetrafluoroethylene

    NASA Technical Reports Server (NTRS)

    Hilado, C. J.; Schneider, J. E.

    1979-01-01

    A sample of polytetrafluoroethylene was evaluated for toxicity of pyrolysis gases, using various test conditions of the toxicity screening test method developed at the University of San Francisco. Time to death appears to be affected by the material of which the pyrolysis tube is made, with Monel tending to give longer times to death than quartz. When quartz tubes are used, time to death seems to be related to carbon monoxide concentration. When Monel tubes are used, carbon monoxide does not appear to be the principal toxicant.

  13. 76 FR 4936 - Granular Polytetrafluoroethylene Resin From Italy

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-27

    ... on granular PTFE resin from Italy and Japan (75 FR 67082-67083 and 67105-67108, November 1, 2010... COMMISSION Granular Polytetrafluoroethylene Resin From Italy AGENCY: United States International Trade... antidumping duty order on granular polytetrafluoroethylene resin (``granular PTFE resin'') from Italy....

  14. 76 FR 8774 - Granular Polytetrafluoroethylene Resin From Japan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-15

    ... COMMISSION Granular Polytetrafluoroethylene Resin From Japan AGENCY: United States International Trade... polytetrafluoroethylene resin from Japan would be likely to lead to continuation or recurrence of material injury. On... December 22, 2010, because ``the domestic parties did not participate in this review.'' (76 FR...

  15. Radiation Degradation of Polytetrafluoroethylene-Lead Composites

    NASA Astrophysics Data System (ADS)

    Karmakar, Sanat; Lawrence, Falix; Mallika, C.; Mudali, U. Kamachi

    2015-11-01

    Composites of polytetrafluoroethylene (PTFE) with Pb (0-15 wt.%) were fabricated and irradiated up to 50 kGy in a 60Co-gamma chamber to evaluate the effect of Pb in improving the radiation tolerance of PTFE. Thermal and mechanical properties were measured for the irradiated and un-irradiated PTFE samples and its composites. The number average molecular weight of PTFE was estimated at different doses from the enthalpy of crystallization values obtained by Differential Scanning Calorimetry. Reduction in the percentage increase in the enthalpy of crystallization and melting of PTFE-15% Pb composite, during irradiation indicated the stabilizing effect of lead on PTFE. Surface morphology of PTFE and its composites revealed that the formation of micro-cracks and blisters in PTFE, owing to radiation damage was controlled by lead. Elongation at break values and SEM images of the irradiated composites indicated that 15% Pb offered better stability to PTFE than 10% Pb.

  16. Shock Wave Treatment of Polytetrafluoroethylene: Structure and Properties

    NASA Astrophysics Data System (ADS)

    Volkova, A. E.; Adamenko, N. A.; Agafonova, G. V.; Kazurov, A. V.

    2016-02-01

    The paper considers changes of the structure and thermomechanical properties of polytetrafluoroethylene pressing after the explosive treatment depending on the thickness of the pressing. Structural changes and defects in samples, preserved even after sintering, were detected.

  17. Light scattering of semitransparent sintered polytetrafluoroethylene films.

    PubMed

    Li, Qinghe; Lee, Bong Jae; Zhang, Zhuomin M; Allen, David W

    2008-01-01

    Polytetrafluoroethylene (PTFE) is a strongly scattering material and has been regarded to have optical properties similar to biological tissues. In the present study, the bidirectional reflectance distribution function (BRDF) and the bidirectional transmittance distribution function (BTDF) of several PTFE films, with thicknesses from 0.11 to 10 mm, are measured using a laser scatterometer at the wavelength of 635 nm. The directional-hemispherical reflectance (R) and transmittance (T) were obtained by integrating BRDF and BTDF for normal incidence. Comparison of the ratio of the measured R and T with that calculated from the adding-doubling method allows the determination of the reduced scattering coefficient. Furthermore, the effect of surface scattering is investigated by measuring the polarization-dependent BRDF and BTDF at oblique incidence. By analyzing the measurement uncertainty of BTDF in the near-normal observation angles at normal incidence, the present authors found that the scattering coefficient of PTFE should exceed 1200 cm(-1), which is much greater than that of biological tissues. On the other hand, the absorption coefficient of PTFE must be less than 0.01 cm(-1), much smaller than that of biological tissues, a necessary condition to achieve R > or =0.98 with a 10-mm-thick slab. PMID:19021442

  18. Antibiotic bonding to polytetrafluoroethylene with tridodecylmethylammonium chloride

    SciTech Connect

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

    1982-09-01

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

  19. Critical appraisal of paclitaxel balloon angioplasty for femoral-popliteal arterial disease.

    PubMed

    Herten, Monika; Torsello, Giovanni B; Schönefeld, Eva; Stahlhoff, Stefan

    2016-01-01

    Peripheral arterial disease, particularly critical limb ischemia, is an area with urgent need for optimized therapies because, to date, vascular interventions often have limited life spans. In spite of initial encouraging technical success after femoropopliteal percutaneous transluminal angioplasty or stenting, postprocedural restenosis remains the major problem. The challenging idea behind the drug-coated balloon (DCB) concept is the biological modification of the injury response after balloon dilatation. Antiproliferative drugs administered via DCBs or drug-eluting stents are able to suppress neointimal hyperplasia, the main cause of restenosis. This article reviews the results of DCB treatments of femoropopliteal and infrapopliteal lesions in comparison to standard angioplasty with uncoated balloons. A systematic literature search was performed in 1) medical journals (ie, MEDLINE), 2) international registers for clinical studies (ie, www.clinicaltrials.gov), and 3) abstracts of scientific sessions. Several controlled randomized trials with follow-up periods of up to 5 years demonstrated the efficacy of paclitaxel -DCB technology. However, calcified lesions seem to affect the efficacy of DCB. Combinations of preconditioning methods with DCBs showed promising results. Although the mechanical abrasion of calcium via atherectomy or laser ablation showed favorable periprocedural results, the long-term impact on restenosis and clinical outcome has to be demonstrated. Major advantages of the DCBs are the rapid delivery of drug at uniform concentrations with a single dose, their efficacy in areas wherein stents have been contraindicated until now (ie, bifurcation, ostial lesions), and in leaving no stent scaffold behind. Reinterventions are easier to perform because DCBs leave no metal behind. Various combinations of DCBs with other treatment modalities may prove to be viable options in future. The follow-up results of clinical studies will evaluate the long-term impact of DCBs. PMID:27621646

  20. 78 FR 11627 - Certain Granular Polytetrafluoroethylene Resin From Italy: Rescission of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-19

    ... International Trade Administration Certain Granular Polytetrafluoroethylene Resin From Italy: Rescission of... on certain granular polytetrafluoroethylene (``PTFE'') resin from Italy. The period of review is... and Countervailing Duty Administrative Reviews and Request for Revocation in Part, 77 FR...

  1. X-ray powder diffraction study of polytetrafluoroethylene

    SciTech Connect

    Lebedev, Yu. A. Korolev, Yu. M.; Polikarpov, V. M.; Ignat'eva, L. N.; Antipov, E. M.

    2010-07-15

    Samples of polytetrafluoroethylene were studied by X-ray diffraction. A quantitative X-ray powder diffraction analysis of three components of the polymer was performed for the first time. All samples of polytetrafluoroethylene were found to be three-phase and consist of one crystalline and two amorphous phases. One of the amorphous phases is composed of low-molecular-weight products. The structure of the latter phase was established for the first time by X-ray diffraction methods and computer simulation.

  2. 76 FR 27663 - Granular Polytetrafluoroethylene Resin From Italy; Scheduling of an Expedited Five-Year Review...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-12

    ... COMMISSION Granular Polytetrafluoroethylene Resin From Italy; Scheduling of an Expedited Five-Year Review Concerning the Antidumping Duty Order on Granular Polytetrafluoroethylene Resin From Italy AGENCY: United... polytetrafluoroethylene resin from Italy would be likely to lead to continuation or recurrence of material injury within...

  3. 76 FR 28455 - Granular Polytetrafluoroethylene Resin From Italy; Scheduling of an Expedited Five-Year Review...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-17

    ... COMMISSION Granular Polytetrafluoroethylene Resin From Italy; Scheduling of an Expedited Five-Year Review Concerning the Antidumping Duty Order on Granular Polytetrafluoroethylene Resin From Italy AGENCY: United... polytetrafluoroethylene resin from Italy would be likely to lead to continuation or recurrence of material injury within...

  4. 21 CFR 872.3680 - Polytetrafluoroethylene (PTFE) vitreous carbon materials.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Polytetrafluoroethylene (PTFE) vitreous carbon materials. 872.3680 Section 872.3680 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices §...

  5. 21 CFR 872.3680 - Polytetrafluoroethylene (PTFE) vitreous carbon materials.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Polytetrafluoroethylene (PTFE) vitreous carbon materials. 872.3680 Section 872.3680 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices §...

  6. Diffusely reflecting paints including polytetrafluoroethylene and method of manufacture

    NASA Technical Reports Server (NTRS)

    Schutt, J. B.; Shai, M. C. (Inventor)

    1985-01-01

    The invention pertains to a high diffuse, reflective paint comprising an alcohol soluble binder, polytetrafluoroethylene (TFE) and an alcohol for coating a substrate and forming an optical reference with a superior Lambertian characteristic. A method for making the paint by first mixing the biner and alcohol, and thereafter by mixing in outgassed TFE is described. A wetting agent may be employed to aid the mixing process.

  7. Responses of endothelial cells, smooth muscle cells, and platelets dependent on the surface topography of polytetrafluoroethylene.

    PubMed

    Lamichhane, Sujan; Anderson, Jordan A; Remund, Tyler; Sun, Hongli; Larson, Mark K; Kelly, Patrick; Mani, Gopinath

    2016-09-01

    In this study, the effect of different structures (flat, expanded, and electrospun) of polytetrafluoroethylene (PTFE) on the interactions of endothelial cells (ECs), smooth muscle cells (SMCs), and platelets was investigated. In addition, the mechanisms that govern the interactions between ECs, SMCs, and platelets with different structures of PTFE were discussed. The surface characterizations showed that the different structures of PTFE have the same surface chemistry, similar surface wettability and zeta potential, but uniquely different surface topography. The viability, proliferation, morphology, and phenotype of ECs and SMCs interacted with different structures of PTFE were investigated. Expanded PTFE (ePTFE) provided a relatively better surface for the growth of ECs. In case of SMC interactions, although all the different structures of PTFE inhibited SMC growth, a maximum inhibitory effect was observed for ePTFE. In case of platelet interactions, the electrospun PTFE provided a better surface for preventing the adhesion and activation of platelets. Thus, this study demonstrated that the responses of ECs, SMCs, and platelets strongly dependent on the surface topography of the PTFE. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2291-2304, 2016. PMID:27119260

  8. Responses of endothelial cells, smooth muscle cells, and platelets dependent on the surface topography of polytetrafluoroethylene.

    PubMed

    Lamichhane, Sujan; Anderson, Jordan A; Remund, Tyler; Sun, Hongli; Larson, Mark K; Kelly, Patrick; Mani, Gopinath

    2016-09-01

    In this study, the effect of different structures (flat, expanded, and electrospun) of polytetrafluoroethylene (PTFE) on the interactions of endothelial cells (ECs), smooth muscle cells (SMCs), and platelets was investigated. In addition, the mechanisms that govern the interactions between ECs, SMCs, and platelets with different structures of PTFE were discussed. The surface characterizations showed that the different structures of PTFE have the same surface chemistry, similar surface wettability and zeta potential, but uniquely different surface topography. The viability, proliferation, morphology, and phenotype of ECs and SMCs interacted with different structures of PTFE were investigated. Expanded PTFE (ePTFE) provided a relatively better surface for the growth of ECs. In case of SMC interactions, although all the different structures of PTFE inhibited SMC growth, a maximum inhibitory effect was observed for ePTFE. In case of platelet interactions, the electrospun PTFE provided a better surface for preventing the adhesion and activation of platelets. Thus, this study demonstrated that the responses of ECs, SMCs, and platelets strongly dependent on the surface topography of the PTFE. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2291-2304, 2016.

  9. Dialysis needle puncture of Wallgrafts placed in polytetrafluoroethylene hemodialysis grafts.

    PubMed

    Rhodes, Erik S; Silas, Anne M

    2005-08-01

    This study evaluates the effect of routine venipuncture at hemodialysis on the durability of Wallgraft covered stents. Thirteen covered stents were placed in six aging, failing polytetrafluoroethylene grafts for treatment of pseudoaneurysms and recurrent stenoses. Four patients did not experience significant graft complications. One graft was ligated for an infected overlying skin ulcer. After surgical revision, the graft remains functional. Another patient experienced fraying of the stent edges and recurrence of a small pseudoaneurysm. Our experience suggests that the Wallgraft covered stent can withstand routine venipuncture at dialysis without flow-limiting stent distortion.

  10. Using electrochemistry in device processing on poly(tetrafluoroethylene) substrates

    SciTech Connect

    Howard, A.J.; Rye, R.R.; Ricco, A.J.; Rieger, D.J.; Lovejoy, M.L.; Sloan, L.R.; Mitchell, M.A.

    1994-10-01

    By combining electrochemical and electroless metal deposition processes with standard optical lithography and wet chemical etching, the authors have developed techniques for the fabrication of fine (<20 {mu}m), adherent, conducting features on poly(tetrafluoroethylene) (PTFE) substrates. These techniques are less expensive and have demonstrated resolution of at least a factor of five better than existing printed wiring board-based processes. Using these PTFE-based processes, the authors have fabricated {approximately} 10 GHz coupled-line quadrature (Lange) couplers, for which test results will be presented.

  11. 76 FR 3614 - Granular Polytetrafluoroethylene Resin From Japan: Final Results of Sunset Review and Revocation...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-20

    ... resin (``PTFE resin'') from Japan. See Initiation of Five-Year (``Sunset'') Review, 75 FR 67082... Antidumping Duty Order; Granular Polytetrafluoroethylene Resin From Japan, 53 FR 32267 (August 24, 1988). On... of Antidumping Duty Orders on Granular Polytetrafluoroethylene Resin from Italy and Japan, 70...

  12. 76 FR 29008 - Granular Polytetrafluoroethylene Resin From Italy; Correction of Notice of Scheduling

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-19

    ... COMMISSION Granular Polytetrafluoroethylene Resin From Italy; Correction of Notice of Scheduling AGENCY... Federal Register May 12, 2011 (76 FR 27663), the Commission published a notice of scheduling of an expedited five-year review on an antidumping duty order on granular polytetrafluoroethylene resin from...

  13. 76 FR 12939 - Granular Polytetrafluoroethylene Resin From Italy: Final Results of Expedited Sunset Review of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-09

    ... International Trade Administration Granular Polytetrafluoroethylene Resin From Italy: Final Results of Expedited... granular polytetrafluoroethylene resin (``PTFE resin'') from Italy. The Department has conducted an... antidumping duty order on PTFE resin from Italy pursuant to section 751(c) of the Tariff Act of 1930,...

  14. Polytetrafluoroethylene transfer film studied with X-ray photoelectron spectroscopy

    NASA Technical Reports Server (NTRS)

    Wheeler, D. R.

    1980-01-01

    Polytetrafluoroethylene (PTFE) was rubbed against nickel in ultrahigh vacuum at loads up to 3.9 N and speeds up to 94 mm/sec. The transfer film formed on the nickel was analyzed using X-ray phototectron spectroscopy. The film was indistinguishable from bulk PTFE except for the possible presence of a small amount of NiF2. The transfer film was found to be about 1 molecule (0.5 nm) thick under all conditions; but at speeds above 10 mm/sec, there was evidence of bulk transfer in the form of fragments as well. The thickness measurements required a choice among conflicting published values of the inelastic mean free path for electrons in polymers. The values chosen gave internally consistent results.

  15. Reconstruction of recurrent diaphragmatic eventration with an elongated polytetrafluoroethylene sheet

    PubMed Central

    Ikeda, Masaki; Sonobe, Makoto; Bando, Toru; Date, Hiroshi

    2013-01-01

    We report the case of a 31-year old woman with recurrence of left diaphragmatic eventration 3 years after a previous surgery for this condition. At the initial occurrence, she had experienced dyspnoea on exercise and subsequently underwent laparoscopic plication of the diaphragm with an endo-stapler at a local hospital. Immediately after the operation, the diaphragm was torn and the intestine entered the thorax. Therefore, plication involving sewing was performed. Then, 3 years later, the patient again experienced dyspnoea and was diagnosed as having recurrence of left diaphragmatic eventration. Observation under thoracoscopy revealed that the centre of the left diaphragm was thin but not torn. We reconstructed the left diaphragm with an elongated polytetrafluoroethylene sheet on the naïve diaphragm. The patient was discharged from our hospital 5 days after surgery. Her respiratory function improved and she has not experienced recurrence. PMID:23644727

  16. Superhydrophobicity of polytetrafluoroethylene thin film fabricated by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Kwong, H. Y.; Wong, M. H.; Wong, Y. W.; Wong, K. H.

    2007-09-01

    Superhydrophobic polytetrafluoroethylene (PTFE) thin films were obtained by pulsed laser deposition (PLD) technique carried out with KrF excimer laser ( λ = 248 nm) of about 1 J/cm 2 at a pressure of 1.33 Pa. The samples exhibit high water contact angle of about 170° and the sliding angle smaller than 2°. From studying the surface morphology of the prepared films, it is believed that the nano-scale surface roughness has enhanced the hydrophobic property of the PTFE. The increase of trapping air and reducing liquid-solid contact area due to the rough surface, as suggested by the Cassie-Baxter's model, should be responsible for superhydrophobicity of the PLD prepared films. This study thus provides a convenient one-step method without using wet-process to produce a superhydrophobic surface with good self-cleaning properties.

  17. Modification of polytetrafluoroethylene surfaces using H2S plasma treatment

    NASA Astrophysics Data System (ADS)

    Vesel, Alenka; Kovac, Janez; Zaplotnik, Rok; Modic, Martina; Mozetic, Miran

    2015-12-01

    A process for modifying the surface properties of polytetrafluoroethylene (PTFE) polymer using sulfur-containing gaseous plasma is presented in this paper. Samples of PTFE foils were treated in pure H2S gaseous plasma sustained by an electrode-less radio-frequency discharge in the E-mode. The samples were kept at a floating potential. X-ray photoelectron spectroscopy, secondary ion mass spectrometry and atomic force microscopy were used to determine the evolution of the surface functionalities and morphology. An extremely thin film of chemically bonded sulfur was formed on the surface after a few seconds of plasma treatment, whereas a treatment duration of more than a minute resulted in the deposition of pure sulfur. The deposited film remained as thin as a few nanometers, even after half an hour of treatment.

  18. Synthesis of polytetrafluoroethylene based olefinic copolymer by gamma radiation grafting

    NASA Astrophysics Data System (ADS)

    Ferreto, H. F. R.; Lima, L. F. C. P.; Parra, D. F.; Zaia, V.; Lugão, A. B.

    2007-12-01

    High speed extrusion of linear low density polyethylene (LLDPE) is limited by processes shortcoming known as 'melt fracture' and 'sharkskin', which are surface defect of the extruded polymer. This defect results in a product with a rough surface that lacks luster and with poor surface properties. The fluoropolymer processing additives are used to eliminate the surface defect by coating the die wall and inducing slip at the coated fluoropolymer surface/LLDPE interface. The aim of this study was to obtain a recycled polytetrafluoroethylene polymer grafted 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 grafting an olefinic monomer the polymeric matrix (PTFE). After a certain time of contact, the copolymer was heat treated to allow recombination and elimination of the radicals, both in a reactive and/or inert atmosphere. The olefinic monomer used was 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). The obtained copolymer (0.2-2.0 wt%) was mixed with LLDPE. The rheological properties of the mixture were determined with a torque rheometer. The results indicated that the developed process rendered a copolymer which when added to LLDPE, improved the extrusion process and eliminated the defect 'melt fracture'.

  19. XPS Study of Plasma- and Argon Ion-Sputtered Polytetrafluoroethylene

    NASA Technical Reports Server (NTRS)

    Golub, Morton A.; Kliss, Mark (Technical Monitor)

    1997-01-01

    The similarity of plasma-polymerized tetrafluoroethylene (PPTFE) and the fluoropolymer film deposited by rf (radio frequency) plasma sputtering (SPTFE) of polytetrafluoroethylene (PTFE), noted earlier in the literature, has been reconfirmed. FT-IR (Fourier Transform Infrared), XPS (X ray Photoelectron Spectroscopy) and UV (ultraviolet) spectroscopy has been employed in apparently the first study to involve preparation of PPTFE and SPTFE in the same reactor and under comparable low-power plasma conditions. Most of the work concerned the use of He or Ar as sputtering gas, but some runs were also carried out with the other rare gases Ne, Kr and Xe. The C1s XPS spectra of SPTFE films displayed a relatively higher content of CF2 groups, and yielded higher F/C (fluorine / carbon) ratios, than PPTFE films, while the SPTFE films were somewhat more transparent in the UV than PPTFE. The F/C ratios for SPTFE were essentially independent of the rare gas used for sputtering. Increasing rf power from 10 to 50 W for Xe plasma-sputtering of PTFE resulted in successively lower F/C ratios (1.55 to 1.21), accompanied by sputtering of the glass reactor occurring at 40 W and above. Some limited XPS, FT-IR and UV data are presented on Ar ion-sputtered PTFE.

  20. Expanding Universe

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    A universe that expands with time. Although the possibility had been raised earlier through theoretical work carried out by Willem de Sitter (1872-1934), Aleksandr Friedmann (1888-1925), and the Abbé Georges Lemaître (1894-1966), that our universe is expanding was first demonstrated observationally in 1929 by Edwin P Hubble (1889-1953), through his measurements of the redshifts in the spectra of ...

  1. Tribological interaction between polytetrafluoroethylene and silicon oxide surfaces

    SciTech Connect

    Uçar, A.; Çopuroğlu, M.; Suzer, S.; Baykara, M. Z.; Arıkan, O.

    2014-10-28

    We investigated the tribological interaction between polytetrafluoroethylene (PTFE) and silicon oxide surfaces. A simple rig was designed to bring about a friction between the surfaces via sliding a piece of PTFE on a thermally oxidized silicon wafer specimen. A very mild inclination (∼0.5°) along the sliding motion was also employed in order to monitor the tribological interaction in a gradual manner as a function of increasing contact force. Additionally, some patterns were sketched on the silicon oxide surface using the PTFE tip to investigate changes produced in the hydrophobicity of the surface, where the approximate water contact angle was 45° before the transfer. The nature of the transferred materials was characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). XPS results revealed that PTFE was faithfully transferred onto the silicon oxide surface upon even at the slightest contact and SEM images demonstrated that stable morphological changes could be imparted onto the surface. The minimum apparent contact pressure to realize the PTFE transfer is estimated as 5 kPa, much lower than reported previously. Stability of the patterns imparted towards many chemical washing processes lead us to postulate that the interaction is most likely to be chemical. Contact angle measurements, which were carried out to characterize and monitor the hydrophobicity of the silicon oxide surface, showed that upon PTFE transfer the hydrophobicity of the SiO{sub 2} surface could be significantly enhanced, which might also depend upon the pattern sketched onto the surface. Contact angle values above 100° were obtained.

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

    PubMed

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

    2016-09-01

    Nanoscale gas bubbles residing on a macroscale hydrophobic surface have a surprising long lifetime (on the order of days) and can serve as cavitation nuclei for initiating inertial cavitation (IC). Whether interfacial nanobubbles (NBs) reside on the infinite surface of a hydrophobic nanoparticle (NP) and could serve as cavitation nuclei is unknown, but this would be very meaningful for the development of sonosensitive NPs. To address this problem, we investigated the IC activity of polytetrafluoroethylene (PTFE) NPs, which are regarded as benchmark superhydrophobic NPs due to their low surface energy caused by the presence of fluorocarbon. Both a passive cavitation detection system and terephthalic dosimetry was applied to quantify the intensity of IC. The IC intensities of the suspension with PTFE NPs were 10.30 and 48.41 times stronger than those of deionized water for peak negative pressures of 2 and 5MPa, respectively. However, the IC activities were nearly completely inhibited when the suspension was degassed or ethanol was used to suspend PTFE NPs, and they were recovered when suspended in saturated water, which may indicates the presence of interfacial NBs on PTFE NPs surfaces. Importantly, these PTFE NPs could sustainably initiate IC for excitation by a sequence of at least 6000 pulses, whereas lipid microbubbles were completely depleted after the application of no more than 50 pulses under the same conditions. The terephthalic dosimetry has shown that much higher hydroxyl yields were achieved when PTFE NPs were present as cavitation nuclei when using ultrasound parameters that otherwise did not produce significant amounts of free radicals. These results show that superhydrophobic NPs may be an outstanding candidate for use in IC-related applications. PMID:27150739

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

    PubMed

    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. PMID:21347955

  4. Airborne Nanoparticle Concentrations in the Manufacturing of Polytetrafluoroethylene (PTFE) Apparel

    PubMed Central

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

    2016-01-01

    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 over 1,000 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 to 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. PMID:21347955

  5. Expanding Universe

    NASA Astrophysics Data System (ADS)

    Schrödinger, E.

    2011-02-01

    Preface; Part I. The de Sitter Universe: 1. Synthetic construction; 2. The reduced model: geodesics; 3. The elliptic interpretation; 4. The static frame; 5. The determination of parallaxes; 6. The Lemaître-Robertson frame; Part II. The Theory of Geodesics: 7. On null geodesics; i. Determination of the parameter for null lines in special cases; ii. Frequency shift; 8. Free particles and light rays in general expanding spaces, flat or hyperspherical; i. Flat spaces; ii. Spherical spaces; iii. The red shift for spherical spaces; Part III. Waves in General Riemannian Space-Time: 9. The nature of our approximation; 10. The Hamilton-Jacobi theory in a gravitational field; 11. Procuring approximate solutions of the Hamilton-Jacobi equation from wave theory; Part IV. Waves in an Expanding Universe: 12. General considerations; 13. Proper vibrations and wave parcels; Bibliography.

  6. Expanding Gravity

    NASA Astrophysics Data System (ADS)

    Aisenberg, Sol

    2005-04-01

    Newton's gravitational constant Gn and Laws of Gravity are based upon observations in our solar system. Mysteries appear when they are used far outside our solar system Apparently, Newton's gravitational constant can not be applied at large distances. Dark matter was needed to explain the observed flat rotational velocity curves of spiral galaxies (Rubin), and of groups of remote galaxies (Zwicky). Our expansion of Newton's gravitational constant Gn as a power series in distance r, is sufficient to explain these observations without using dark matter. This is different from the MOND theory of Milgrom involving acceleration. Also, our Expanded Gravitational Constant (EGC) can show the correct use of the red shift. In addition to the Doppler contribution, there are three other contributions and these depend only upon gravity. Thus, velocity observations only based on the red shift can not be used to support the concept of the expanding universe, the accelerating expansion, or dark energy. Our expanded gravity constant can predict and explain Olbers' paradox (dark sky), and the temperature of the CMB (cosmic microwave background). Thus, CMB may not support the big bang and inflation.

  7. X-ray diffraction phase analysis of the crystalline phase of polytetrafluoroethylene

    SciTech Connect

    Lebedev, Yu. A. Korolev, Yu. M.; Rebrov, A. V.; Ignat'eva, L. N.; Antipov, E. M.

    2010-07-15

    Samples of ultradispersed polytetrafluoroethylene, which were prepared with the use of different technological approaches, were studied by X-ray diffraction. The samples were found to belong to the monoclinic system. For some samples, basal reflections, which can be related to paraffins, were found for the first time. This indicates that polymer chains can form yet another type of monoclinic structure.

  8. A technique to eliminate subgingival cement adhesion to implant abutments by using polytetrafluoroethylene tape.

    PubMed

    Hess, Timothy A

    2014-08-01

    Residual excess cement adhered subgingivally to an implant abutment has the potential to cause periimplant mucositis or periimplant disease. This article describes a procedure in which polytetrafluoroethylene (PTFE) tape is used to protect dental cements from adhering to the implant abutment. This technique ensures complete removal of cement from the implant abutment after seating of the crown. PMID:24529837

  9. Expanded Yegua

    SciTech Connect

    Hart, R.E.; Grayson, S.; Benes, J.

    1988-01-01

    The upper Eocene Yegua Formation expands dramatically across a regional flexure generally 12-15 km wide. During each of several postulated Yegua sea level drops, this flexure became a focal point for deltaic deposition of good to excellent reservoir-quality sands. From the western edge of the Houston salt dome basin to the San Marcos arch, this trend has yielded, since 1982, at least seven noteworthy discoveries: Toro Grande and Lost Bridge fields in Jackson County, and Black Owl, Shanghai, Shanghai East, El Campo, and Phase Four fields in Wharton County, Texas. El Campo field in Wharton County, Texas, was discovered in December 1985 by Ladd Petroleum Corporation with the drilling of the Ladd Petroleum 1 Popp well. Mud logs acquired while drilling indicated that a very sandy reservoir, with encouraging quantities of natural gas and condensate had been encountered. Subsequent open-hold logging generated more questions than answers about the prospective sand section. Additional open hole logs (EPT/ML,SHDT) were run to identify what turned out to be an extremely laminated sand-shale sequence over 400 ft thick. Subsequent development drilling and the acquisition of a 120 ft whole core provided valuable data in analyzing this prolific, geopressured natural gas and condensate Yegua reservoir. Whole-core data, open-hole logs, and computer logs were integrated to develop petro-physical evaluation procedures and to determine the environment of deposition. El Campo field is believed to represent an extremely thick, delta front slope to distal delta front facies.

  10. The effects of low earth orbit atomic oxygen on the properties of Polytetrafluoroethylene

    NASA Astrophysics Data System (ADS)

    Hooshangi, Zhila; Hossein Feghhi, Seyed Amir; Saeedzadeh, Rezgar

    2016-02-01

    Polymers are widely used in space systems as the structural materials. The low earth orbit (LEO) space environment includes hazards such as atomic oxygen. Exposure of polymeric materials to atomic oxygen results in destructive effects on the chemical, electrical, thermal, optical and mechanical properties as well as surface degradation. In the present work, the effects of atomic oxygen on the mechanical, thermal, and optical properties of Polytetrafluoroethylene film have been investigated. The atomic oxygen density was calculated by SPENVIS tool. After the atomic oxygen exposure by using radio-frequency (RF) plasma source, the appearance of the samples changed, and the mass of the samples reduced because of outgassing. The results of thermal analysis showed that atomic oxygen flux does not affect thermal degradation of samples regarding TGA diagrams. By increasing the atomic oxygen flux, the amount of absorbance increased showing that atomic oxygen had damaged the surface of Polytetrafluoroethylene, and it had oxidized the surface of the polymer.

  11. Near Infrared 45°/0° Reflectance Factor of Pressed Polytetrafluoroethylene (PTFE) Powder

    PubMed Central

    Nadal, Maria E.; Barnes, P. Yvonne

    1999-01-01

    Pressed polytetrafluoroethylene (PTFE) powder is commonly used as a reflectance standard for bidirectional and hemispherical geometries. The wavelength dependence of the reflectance factor of PTFE is presented for the near-infrared spectral region (800 nm to 1600 nm) for the 45°/0° geometry, as well as in the visible spectral region (380 nm to 800 nm) for comparison with previously published results.

  12. Nano-microstructured, superhydrophobic, and infrared transparent polytetrafluoroethylene/diamond films

    NASA Astrophysics Data System (ADS)

    Horowitz, Flavio; Brandão, Lívia E. V. S.; Camargo, Kelly C.; Michels, Alexandre F.; Balzaretti, Naira M.

    2013-01-01

    A self-assembled polytetrafluoroethylene (PTFE) nanostructure is deposited on microcrystalline diamond (MCD) films, by use of physical and chemical vapor deposition in a two-step process, to produce (fully) superhydrophobic surfaces: high water contact angle (static, 165±2 deg), very low hysteresis (dynamic, ˜4 deg), and associated sliding angle (1 deg 5‧±15‧), thus combining the diamond infrared transparency and self-cleaning properties. These are interpreted in light of Wenzel and Cassie-Baxter wetting models, associated with structural microscopy of nano-micro rough PTFE/MCD surfaces, and present a promising perspective for self-cleaning infrared optics applications.

  13. Fabrication of super-hydrophobic surfaces on aluminum alloy substrates by RF-sputtered polytetrafluoroethylene coatings

    SciTech Connect

    Wang, Yang; Liu, Xiao Wei; Zhang, Hai Feng Zhou, Zhi Ping

    2014-03-15

    In this work, we present a method of fabricating super-hydrophobic surface on aluminum alloy substrate. The etching of aluminum surfaces has been performed using Beck's dislocation etchant for different time to create micrometer-sized irregular steps. An optimised etching time of 50 s is found to be essential before polytetrafluoroethylene (PTFE) coating, to obtain a highest water contact angle of 165±2° with a lowest contact angle hysteresis as low as 5±2°. The presence of patterned microstructure as revealed by scanning electron microscopy (SEM) together with the low surface energy ultrathin RF-sputtered PTFE films renders the aluminum alloy surfaces highly super-hydrophobic.

  14. A facile method to fabricate superamphiphobic polytetrafluoroethylene surface by femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Fan, Wenzhong; Qian, Jing; Bai, Feng; Li, Yangbo; Wang, Chengwei; Zhao, Quan-Zhong

    2016-01-01

    We report a simple method to fabricate superamphiphobic polytetrafluoroethylene (PTFE) surfaces by femtosecond laser direct irradiation. After femtosecond laser direct writing, a dual-scale composite structure combined a groove-like microstructure with a lamellar submicron structure forms on the PTFE surface, enhancing its hydrophobic properties with a contact angle increasing from 109° to 156.88°, as well as exhibiting transition from intrinsic oleophilicity to superoleophobicity. Meanwhile, the wettability of the surface can be tuned by changing the roughness and the interval between two adjacent micro-grooves. Furthermore, we also explain the relationship between the interval width and the contact angle using the Cassie-Baxter model.

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

    NASA Astrophysics Data System (ADS)

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

    2001-07-01

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

  16. Interaction of proton microbeam with the inner surface of a polytetrafluoroethylene macrocapillary

    NASA Astrophysics Data System (ADS)

    Rajta, I.; Nagy, G. U. L.; Bereczky, R. J.; Tőkési, K.

    2015-07-01

    The transmission of 1 MeV proton microbeam through a single, cylindrically shaped, micrometre-sized polytetrafluoroethylene capillary was studied. The capillary axis was tilted with respect to the axis of the incident ion beam. The tilting, the aspect ratio of the capillary and the small beam divergence disabled the geometrical transmission of the beam through the target. The time dependence of the intensity, the charge-state and the deflection of the transmitted beam were investigated. We found that pure guided transmission of a MeV/amu energy ion beam is possible through an insulator capillary.

  17. Temperature dependence of catalytic cyclohexane partial oxidation in a polytetrafluoroethylene reactor

    NASA Astrophysics Data System (ADS)

    Lončarević, D.; Krstić, J.; Banković, P.; Anić, S.; Čupić, Ž.

    2007-09-01

    Polymer-supported Co(II) catalyst was prepared and its activity and selectivity in the partial oxidation of cyclohexane was determined at several temperatures in a polytetrafluoroethylene reactor (PTFE). The catalyst was characterized by means of SEM-EDX, FTIR, diffuse reflectance UV-Vis, N2 sorption, and mecury porosimetry. Activation energies were determined under steady state conditions for the net production of cyclohexanone and cyclohexanol and for cyclohexane and oxygen net consumption. Some activation energies were lower than the ones reported for the uncatalyzed process, indicating that the catalyst played an important role in the initiation of the free-radical reaction.

  18. Periodic and high-temperature disordered conformations of polytetrafluoroethylene chains: an ab initio modeling.

    PubMed

    D'Amore, Maddalena; Talarico, Giovanni; Barone, Vincenzo

    2006-02-01

    We report here the main results of a successful attempt to predict some macroscopic properties of representative polymers of technological relevance both in regular and disordered forms by using first principle quantum mechanical approaches at microscopic level. Until now, the prediction of the structural and thermal properties of those polymers has been mostly a domain of molecular mechanics methods. To overcome the limits of those classical computational tools whenever physical properties are significantly influenced by stereoelectronic effects (e.g., electron rich substituents), we employed methods rooted in the Density Functional Theory (DFT). A general computational strategy including the proper choice of periodic boundary conditions (PBC), functional, basis set, and model system size, has been tested and validated for saturated polymers such as polyethylene and isotactic/syndiotactic polypropylenes. On the basis of these results, a comprehensive study of poly(tetrafluoroethylene) (PTFE) chains in both regular periodic and disordered conformations has been performed. A statistical approach has been next applied to obtain the thermal concentration of defects and to reproduce the thermal behavior of the investigated polymer. At the end, a very good agreement with experimental X-ray diffraction and IR results has been achieved, definitely reaching a good understanding of the widely studied disorder phenomenon determining the main technological properties of poly(tetrafluoroethylene) (the trade Teflon) and, at the same time, identifying the proper computational tools to investigate perfluoro-compounds and other complex polymeric systems.

  19. Potential space debris shield structure using impact-initiated energetic materials composed of polytetrafluoroethylene and aluminum

    NASA Astrophysics Data System (ADS)

    Wu, Qiang; Zhang, Qingming; Long, Renrong; Zhang, Kai; Guo, Jun

    2016-03-01

    A whipple shield using Al/PTFE (polytetrafluoroethylene) energetic material to protect against space debris is presented. The hypervelocity impact characteristics were investigated experimentally using a two-stage light gas gun at velocities between 3 and 6 km/s. A good protection of the shield was obtained through comparative experiments which used the same bumper areal density. The results showed that the critical projectile diameter can be improved by 28% by contrast with the Christiansen ballistic limit equations. The Al/PTFE energetic material bumper can break up the projectile into smaller, less massive, and slower projectiles due to the combined effect of impact and explosion, thereby producing a sharp rise in the spacecraft protection ability.

  20. Observation of Individual Fluorine Atoms from Highly Oriented Poly(Tetrafluoroethylene) Films by Atomic Force Microscopy

    NASA Technical Reports Server (NTRS)

    Lee, J. A.

    2000-01-01

    Direct observation of the film thickness, molecular structure, and individual fluorine atoms from highly oriented poly(tetrafluoroethylene) (PTFE) films were achieved using atomic force microscopy (AFM). A thin PTFE film is mechanically deposited onto a smooth glass substrate at specific temperatures by a friction-transfer technique. Atomic resolution images of these films show that the chain-like helical structures of the PTFE macromolecules are aligned parallel to each other with an intermolecular spacing of 5.72 A, and individual fluorine atoms are clearly observed along these twisted molecular chains with an interatomic spacing of 2.75 A. Furthermore, the first direct AFM measurements for the radius of the fluorine-helix, and of the carbon-helix in sub-angstrom scale are reported as 1.7 and 0.54 A respectively.

  1. Tensile deformation of polytetrafluoroethylene hollow fiber membranes used for water purification.

    PubMed

    Yonezu, Akio; Iio, Shouichi; Itonaga, Takehiro; Yamamura, Hiroshi; Chen, Xi

    2014-01-01

    The tensile deformation behavior of polytetrafluoroethylene (PTFE) hollow fiber membranes is studied. PTFE membranes at present have sub-micron pores with an open cell structure, which plays a critical role in water purification. One of the main challenges in water purification is that the pore structure becomes covered with biofouling, leading to blocked pores. To maintain the capacity for water purification, physical cleaning along with mechanical deformation is usually conducted. Thus, it is crucial to understand the mechanical properties, in particular the deformation behavior, of the membrane fibers. Using uniaxial tension experiments, we established a fundamental discrete model to describe the deformation behavior of a porous structure using a finite element method. The present model enables the prediction of the macroscopic deformation behavior of the membrane, by taking into account the changes of pore structure. The insight may be useful for porous membrane fabrication and provide insights for the reliable operation of water purification.

  2. Air-to-surface missile wound of the thorax reconstructed with a polytetrafluoroethylene patch: case report.

    PubMed

    Flis, V; Antonic, J; Crnjac, A; Zorko, A

    1993-11-01

    A method of reconstructing a chest wall defect following non-guided air-to-surface missile injury is described. The wall defect was simply closed with a polytetrafluoroethylene patch. The high risk of infection following use of the described method is well recognized. No infection occurred in this case. It could be stated that under the exigencies of the moment the use of prosthetic material to reconstruct the chest is not invariably followed by infection. However, when the patient is stable this latter problem can then be addressed by a variety of standard methods. It is concluded that the described method is particularly suitable in war circumstances, when it is usually necessary to attend to a large number of patients in a short period of time. PMID:8230352

  3. Removing hepatitis C virus from polytetrafluoroethylene-coated orthodontic archwires and other dental instruments.

    PubMed

    Ramadan, A A

    2003-05-01

    The efficacy of removing, rather than destroying, hepatitis C virus (HCV) from polytetrafluoroethylene (PTFE)-coated orthodontic archwirs was tested. PTFE-coated archwires, pieces of PTFE and endodontic files (20 each) were immersed in HCV-infected blood for 24 hours. Half were washed under running water for 10 seconds while the remainder were thoroughly scrubbed with a toothbrush under running water for 10 seconds. Items were kept in separate dishes of distilled water for 24 hours. Reverse transcription polymerase chain reaction was used for viral replication. Viruses were detected by the gel method using a transilluminator. Only scrubbed PTFE pieces and coated archwires were negative for HCV. This suggests that PTFE coating of dental instruments inhibited HCV adhesion when thoroughly scrubbed.

  4. Water dispersible polytetrafluoroethylene microparticles prepared by grafting of poly(acrylic acid)

    NASA Astrophysics Data System (ADS)

    Yang, Changqiao; Xu, Lu; Zeng, Hongyan; Tang, Zhongfeng; Zhong, Lei; Wu, Guozhong

    2014-10-01

    Due to the hydrophobic nature and high gravimetric density, it is very difficult to obtain water dispersible polytetrafluoroethylene (PTFE) powder. In this work, hydrophilic PTFE microparticles were successfully prepared by grafting of poly(acrylic acid) onto PTFE micropowder via a pre-irradiation method. The as-obtained hydrophilic PTFE microparticles were analyzed by FT-IR, 1H NMR, CA, SEM and TGA. After neutralization by sodium hydroxide, the water contact angle decreased from 145.69° for pristine PTFE to 63.38° for PTFE-g-NaAA. The obtained micropowder can be easily dispersed in water to form a dispersion with very high stability. Furthermore, the presence of grafted PAA shows no obvious influence on degradation temperature of PTFE backbones.

  5. X-ray photoelectron and mass spectroscopic study of electron irradiation and thermal stability of polytetrafluoroethylene

    NASA Technical Reports Server (NTRS)

    Wheeler, Donald R.; Pepper, Stephen V.

    1990-01-01

    Polytetrafluoroethylene (PTFE) was subjected to 3 keV electron bombardment and then heated in vacuum to 300 C. The behavior of the material as a function of radiation dose and temperature was studied by X-ray photoelectron spectroscopy (XPS) of the surface and mass spectroscopy of the species evolved. A quantitative comparison of the radiation dose rate with that in other reported studies showed that, for a given total dose, the damage observed by XPS is greater for higher dose rates. Lightly damaged material heated to 300 C evolved saturated fluorocarbon species, whereas unsaturated fluorocarbon species evolved from heavily damaged material. After heating the heavily damaged material, those features in the XPS that were associated with damage diminished, giving the appearance that the radiation damage annealed. The apparent annealing of the radiation damage was found to be due to the covering of the network by saturated fragments that easily diffused through the decomposed material to the surface region upon heating.

  6. Improved adhesion of Ni films on X-ray damaged polytetrafluoroethylene

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    The considered investigation shows that the adhesion of evaporated Ni on polytetrafluoroethylene (PTFE) is enhanced by irradiating the PTFE surface prior to evaporation. Evidence obtained with the aid of X-ray photoelectron spectroscopy is presented concerning the association of the enhanced adhesion with an interfacial chemical reaction. Evaporated Ni clearly adheres better to the X-ray damaged PTFE surface than to the undamaged surface. There is evidence that the improved adhesion is not related to the Ni-C bond, but rather to the NiF2. A possible mechanism which may be consistent with the data is the formation of a F-Ni-C complex, where C is a member of the polymer chain.

  7. Effect of X-ray flux on polytetrafluoroethylene in X-ray photoelectron spectroscopy

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    The effect of the X-ray flux in X-ray photoelectron spectroscopy (STAT) on the constitution of the polytetrafluoroethylene (PTFE) surface has been examined. The radiation dose rate for our specimen was about 10 to the 7th rad/s. The structure, magnitude and binding energy of the C(1s) and F(1s) features of the XPS spectrum and the mass spectrum of gaseous species evolved during irradiation are observed. The strong time dependence of these signals over a period of several hours indicated that the surface constitution of PTFE is greatly affected by this level of radiation dose. The results are consistent with the development of a heavily cross-linked or branched structure in the PTFE surface region and the evolution of short chain fragments into the gas phase.

  8. Surface energy changes produced by ultraviolet-ozone irradiation of poly(methylmethacrylate), polycarbone and polytetrafluoroethylene

    NASA Technical Reports Server (NTRS)

    Ponter, A. B.; Jones, W. R., Jr.; Jansen, R. H.

    1994-01-01

    Contact angles of water and methylene iodide were measured as a function of UV/O3 treatment time for three polymers: poly(methylmethacrylate) (PMMA), polycarbonate, and polytetrafluoroethylene (PTFE). Surface roughnesses were also measured. Surface free energies were then calculated using relationships developed by Kaelble and Neumann. The surface energy of polycarbonate was found to increase (60 percent) during UV/O3 treatment. However, calculations on PMMA were hampered by the formation of a water soluble surface product. On PTFE surfaces, the UV/O3 treatment etched the surface causing large increases in surface roughness, rendering contact angle measurements impossible. It is concluded that care must be taken in interpreting contact angle measurements and surface energy calculations on UV/O3 treated polymer surfaces.

  9. Stabilization of positive charge on polytetrafluoroethylene electret films treated with titanium-tetrachloride vapor

    SciTech Connect

    Rychkov, Dmitry; Gerhard, Reimund

    2011-03-21

    The surface of polytetrafluoroethylene films was treated with titanium-tetrachloride vapor. The treatment was carried out in a flow reactor by means of molecular-layer deposition, a method from the arsenal of chemical nanotechnology. X-ray photoelectron spectroscopy reveals that such a treatment results in considerable changes in the chemical composition at and near the surface of the fluoropolymer film. Both, defluorination and oxidation of the surface were observed. At the same time, samples treated with titanium tetrachloride show a significant enhancement in the thermal stability of the positive homocharge. The thermally stimulated surface-potential-decay curves were observed to shift to higher temperatures by more than 100 deg. C

  10. Pulsed electron beam deposition of highly oriented thin films of polytetrafluoroethylene

    NASA Astrophysics Data System (ADS)

    Chandra, Vimlesh; Manoharan, Solomon S.

    2008-04-01

    Thin films of polytetrafluoroethylene (PTFE) were deposited by pulsed electron deposition (PED) technique. The transmission electron microscopy (TEM) image of the RT fabricated (20 Å thick) film on carbon coated copper grid shows crystalline nature. Infrared spectra show one to one correspondence between PED ablated film and the PTFE bulk target. The asymmetrical and symmetrical -CF 2- stretching modes were observed at 1220 and 1156 cm -1, respectively. The -CF 2- wagging and bending modes occur at 644 and 512 cm -1, respectively. X-ray diffraction patterns of the film deposited at room temperature (RT) show oriented film along (1 0 0) plane of hexagonal structure and the crystalline nature is retained up to 300 °C on vacuum annealing. The room temperature fabricated film shows smooth and pin hole free surface whereas post-annealing brings discontinuity, roughness and pin holes.

  11. Adhesion and transfer of polytetrafluoroethylene to tungsten studied by field ion microscopy

    NASA Technical Reports Server (NTRS)

    Brainard, W. A.; Buckley, D. H.

    1972-01-01

    Mechanical contacts between polytetrafluoroethylene (PTFE) and tungsten field ion tips were made in situ in the field ion microscope. Both load and force of adhesion were measured for varying contact times and for clean and contaminated tungsten tips. Strong adhesion between the PTFE and clean tungsten was observed at contact times greater than 2.5 min (forces of adhesion were greater than three times the load). For times less than 2.5 min, the force of adhesion was immeasurably small. The increase in adhesion with contact time after 2.5 min can be attributed to the increase in true contact area by creep of PTFE. No adhesion was measurable at long contact times with contaminated tungsten tips. Neon field ion micrographs taken after the contacts show many linear and branched arrays which appear to represent PTFE that remains adhered to the surface even at the high electric fields required for imaging.

  12. Extreme ultraviolet (EUV) surface modification of polytetrafluoroethylene (PTFE) for control of biocompatibility

    NASA Astrophysics Data System (ADS)

    Ahad, Inam Ul; Butruk, Beata; Ayele, Mesfin; Budner, Bogusław; Bartnik, Andrzej; Fiedorowicz, Henryk; Ciach, Tomasz; Brabazon, Dermot

    2015-12-01

    Extreme ultraviolet (EUV) surface modification of polytetrafluoroethylene (PTFE) was performed in order to enhance the degree of biocompatibility. Polymer samples were irradiated by different number of EUV shots using a laser-plasma based EUV source in the presence of nitrogen gas. The physical and chemical properties of EUV modified PTFE samples were studied using Atomic Force Microscopy, X-ray photoelectron spectroscopy and water contact angle (WCA) methods. Pronounced wall type micro and nano-structures appeared on the EUV treated polymer surfaces resulting in increased surface roughness and hydrophobicity. Stronger cell adhesion and good cell morphology were observed on EUV modified surfaces by in-vitro cell culture studies performed using L929 fibroblasts.

  13. Preparation of microstructure-controllable superhydrophobic polytetrafluoroethylene porous thin film by vacuum thermal-evaporation

    NASA Astrophysics Data System (ADS)

    Yi, Na; Bao, Shanhu; Zhou, Huaijuan; Xin, Yunchuan; Huang, Aibin; Ma, Yining; Li, Rong; Jin, Ping

    2016-09-01

    The three-dimensional porous network polytetrafluoroethylene (PTFE) thin films were achieved by a vacuum technique through evaporating the pure PTFE powders. The surfaces of PTFE thin films showed various morphologies by adjusting the evaporation temperature and the corresponding contact angle ranging from 133° to 155°. Further analyses of surface chemical composition and morphology by FTIR and FE-SEM revealed that the origin of hydrophobicity for the PTFE thin films could be ascribed to the fluorine-containing groups and the surface morphologies, indicating that abundant -CF2 groups and network structures with appropriate pore sizes played a vital role in superhydrophobicity. By characterization of UV-Vis, the films also showed high transmittance and antireflection effect. The films prepared by this simple method have potential applications such as waterproof membrane and self-cleaning coating.

  14. Preparation and characterization of porous composite filter medium by polytetrafluoroethylene foam coating.

    PubMed

    Park, Byung Hyun; Lee, Myong-Hwa; Kim, Sang Bum; Kim, Gyung Soo; Jo, Young Min

    2010-02-01

    The high costs of ceramic and Teflon filter media for hot gas cleaning has limited their industrial applications. This paper presents a foam coating technology that can be used to produce an inexpensive and highly efficient filter for industrial applications. A new apparatus was designed and built that coats porous glass mats with liquid-phase polytetrafluoroethylene (PTFE). The machine generates bubbles, enables the formation of uniform micropores less than 45 microm in diameter, and produces a product with air permeability greater than 5.5 cm3/cm2/sec. The resulting filter was found to be thermally stable up to 270 degrees C without any visible distortion and was comparable in dust collection efficiency to other commercial filter media. In addition, its de-dusting efficiency was greater than 85%, which is similar to that of other test filter media.

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

    PubMed

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

    2014-01-01

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

  16. Characterization of plastic deformation and chemical reaction in titanium-polytetrafluoroethylene mixture

    NASA Astrophysics Data System (ADS)

    Davis, Jeffery Jon

    1998-09-01

    The subject of this dissertation is the deformation process of a single metal - polymer system (titanium - polytetrafluoroethylene) and how this process leads to initiation of chemical reaction. Several different kinds of experiments were performed to characterize the behavior of this material to shock and impact. These mechanical conditions induce a rapid plastic deformation of the sample. All of the samples tested had an initial porosity which increased the plastic flow condition. It is currently believed that during the deformation process two important conditions occur: removal of the oxide layer from the metal and decomposition of the polymer. These conditions allow for rapid chemical reaction. The research from this dissertation has provided insight into the complex behavior of plastic deformation and chemical reactions in titanium - polytetrafluoroethylene (PTFE, Teflon). A hydrodynamic computational code was used to model the plastic flow for correlation with the results from the experiments. The results from this work are being used to develop an ignition and growth model for metal/polymer systems. Three sets of experiments were used to examine deformation of the 80% Ti and 20% Teflon materials: drop- weight, gas gun, and split-Hopkinson pressure bar. Recovery studies included post shot analysis of the samples using x-ray diffraction. Lagrangian hydrocode DYNA2D modeling of the drop-weight tests was performed for comparison with experiments. One of the reactions know to occur is Ti + C → TiC (s) which results in an exothermic release. However, the believed initial reactions occur between Ti and fluorine which produces TixFy gases. The thermochemical code CHEETAH was used to investigate the detonation products and concentrations possible during Ti - Teflon reaction. CHEETAH shows that the Ti - fluorine reactions are thermodynamically favorable. This research represents the most comprehensive to date study of deformation induced chemical reaction in metal/polymers.

  17. Temperature measurements for shocked polymethylmethacrylate, epoxy resin, and polytetrafluoroethylene and their equations of state

    NASA Astrophysics Data System (ADS)

    Bordzilovskii, S. A.; Karakhanov, S. M.; Merzhievskii, L. A.; Voronin, M. S.

    2016-10-01

    This paper presents the results of computational and experimental studies of the temperature along the shock adiabat for three polymers. Measurements of the brightness temperatures of shock-compressed epoxy resin and polymethylmethacrylate and the brightness and color temperatures of shock-compressed polytetrafluoroethylene were carried out. The temperatures of the shock-compressed polymethylmethacrylate were determined in the range 1390-1900 K for shock pressures of 22-39 GPa. Similar measurements performed for epoxy resin in the pressure range of 18-40 GPa showed values of 940-1900 K, and the temperatures of polytetrafluoroethylene in the pressure range of 30-50 GPa were equal to 2000-3200 K. The equation of state for the three polymers with a nonspherical strain tensor was constructed to describe shock-wave and high-temperature processes in a wide range of thermodynamic parameters. In the proposed model, two Grüneisen parameters were used: the thermodynamic parameter corresponding to intrachain vibrations and the lattice parameter representing the contribution of interchain vibrations. The brightness temperatures of shocked-compressed polymethylmethacrylate and epoxy resin showed a good agreement with calculations using the proposed model and with the results of earlier calculation methods. Time dependences of the observed intensity of light were used to determine the absorption coefficients of the shocked polymers and estimate the effective thickness of the radiating layer. A typical feature of all the polymers is the width of the radiating layer of 0.8 to 2.5 mm, depending on the material and shock pressure.

  18. What Expands in an Expanding Universe?

    PubMed

    Pacheco, José A De Freitas

    2015-01-01

    In the present investigation, the possible effects of the expansion of the Universe on systems bonded either by gravitational or electromagnetic forces, are reconsidered. It will be shown that the acceleration (positive or negative) of the expanding background, is the determinant factor affecting planetary orbits and atomic sizes. In the presently accepted cosmology (ΛCDM) all bonded systems are expanding at a decreasing rate that tends to be zero as the universe enters in a de Sitter phase. It is worth mentioning that the estimated expansion rates are rather small and they can be neglected for all practical purposes. PMID:26628035

  19. What Expands in an Expanding Universe?

    PubMed

    Pacheco, José A De Freitas

    2015-01-01

    In the present investigation, the possible effects of the expansion of the Universe on systems bonded either by gravitational or electromagnetic forces, are reconsidered. It will be shown that the acceleration (positive or negative) of the expanding background, is the determinant factor affecting planetary orbits and atomic sizes. In the presently accepted cosmology (ΛCDM) all bonded systems are expanding at a decreasing rate that tends to be zero as the universe enters in a de Sitter phase. It is worth mentioning that the estimated expansion rates are rather small and they can be neglected for all practical purposes.

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

    PubMed

    Wang, Shibo; Niu, Chengchao

    2016-01-01

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

  1. Triboelectrification-Induced Large Electric Power Generation from a Single Moving Droplet on Graphene/Polytetrafluoroethylene.

    PubMed

    Kwak, Sung Soo; Lin, Shisheng; Lee, Jeong Hwan; Ryu, Hanjun; Kim, Tae Yun; Zhong, Huikai; Chen, Hongsheng; Kim, Sang-Woo

    2016-08-23

    Recently, several reports have demonstrated that a moving droplet of seawater or ionic solution over monolayer graphene produces an electric power of about 19 nW, and this has been suggested to be a result of the pseudocapacitive effect between graphene and the liquid droplet. Here, we show that the change in the triboelectrification-induced pseudocapacitance between the water droplet and monolayer graphene on polytetrafluoroethylene (PTFE) results in a large power output of about 1.9 μW, which is about 100 times larger than that presented in previous research. During the graphene transfer process, a very strong negative triboelectric potential is generated on the surface of the PTFE. Positive and negative charge accumulation, respectively, occurs on the bottom and the top surfaces of graphene due to the triboelectric potential, and the negative charges that accumulate on the top surface of graphene are driven forward by the moving droplet, charging and discharging at the front and rear of the droplet. PMID:27415838

  2. Stability of nonfouling electroless nickel-polytetrafluoroethylene coatings after exposure to commercial dairy equipment sanitizers.

    PubMed

    Huang, Kang; Goddard, Julie M

    2015-09-01

    Application of nonfouling coatings on thermal processing equipment can improve operational efficiency. However, to enable effective commercial translation, a need exists for more comprehensive studies on the stability of nonfouling coatings after exposure to different sanitizers. In the current study, the influence of different commercial dairy equipment sanitizers on the nonfouling properties of stainless steel modified with electroless Ni-polytetrafluoroethylene (PTFE) coatings was determined. Surface properties, such as dynamic contact angle, surface energy, surface morphology, and elemental composition, were measured before and after the coupons were exposed to the sanitizers for 168 cleaning cycles. The fouling behavior of Ni-PTFE-modified stainless steel coupons after exposure was also evaluated by processing raw milk on a self-fabricated benchtop-scale plate heat exchanger. The results indicated that peroxide sanitizer had only minor effect on the Ni-PTFE-modified stainless steel surface, whereas chlorine- and iodine-based sanitizers influenced the surface properties drastically. The coupons after 168 cycles of exposure to peroxide sanitizer accumulated the least amount of fouling material (4.44±0.24mg/cm(2)) compared with the coupons exposed to the other 3 sanitizers. These observations indicated that the Ni-PTFE nonfouling coating retained antifouling properties after 168 cycles of exposure to peroxide-based sanitizer, supporting their potential application as nonfouling coatings for stainless steel dairy processing equipment.

  3. Enhanced cathode performance of nano-sized lithium iron phosphate composite using polytetrafluoroethylene as carbon precursor

    NASA Astrophysics Data System (ADS)

    Avci, Ercan

    2014-12-01

    Herein we report a facile and efficient solid state synthesis of carbon coated lithium iron phosphate (LiFePO4/C) cathode material achieved through the pyrolysis of polytetrafluoroethylene (PTFE). The current investigation is comparatively analyzed with the results of the composites of LiFePO4/C (LFP/C) synthesized using polystyrene-block-polybutadiene (PS-b-PBD), polyethyhylene (PE) and sucrose as carbon precursors. The optimized LFP/CPTFE composite is synthesized at 700 °C using 10 wt.% PTFE. The composite exhibits remarkable improvement in capacity, cyclability and rate capability compared to those of LFP/C synthesized using (PS-b-PBD), PE and sucrose. The specific discharge capacities as high as 166 mA h g-1 (theoretical capacity: 170 mA h g-1) at 0.2 C and 114 mA h g-1 at 10 C rates were achieved with LFP/CPTFE. In addition, the composite exhibits a long-term cycling stability with the capacity loss of only 11.4% after 1000 cycles. PTFE shifts the size distribution of the composite to nanometer scale (approximately 120 nm), however the addition of sucrose and other polymers do not have such an effect. According to TEM and XPS analysis, LFP/CPTFE particles are mostly coated with a few nanometers thick carbon layer forming a core-shell structure. Residual carbon does not contain fluorine.

  4. Dielectric Properties of Layered ZnTa2O6/Poly(tetrafluoroethylene) Composites

    NASA Astrophysics Data System (ADS)

    Jeon, Chang Jun; Kim, Eung Soo

    2012-11-01

    The effects of ZnTa2O6 content and layered structure on the dielectric properties of ZnTa2O6/poly(tetrafluoroethylene) (PTFE) composites were investigated at microwave frequency. With increasing ZnTa2O6 content, the dielectric constant (K) and dielectric loss (tan δ) of the composites increased due to the K values of the individual components and the microstructure. For the composites with layered structures, tan δ was dependent on the internal strain of the composites. Several types of theoretical models were employed to predict the effective K of the composites and the predicted values were compared with experimental data. The temperature coefficient of resonant frequency (TCF) was also discussed as it characterises the thermal stability of the composites. Typically, K of 4.24, tan δ of 1.36 ×10-3 and, TCF of 4.75 ppm/°C were obtained for the single layered PTFE composites with 0.2 volume fraction (Vf) of ZnTa2O6.

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

    SciTech Connect

    Wang, Liu; Liu, Jinxu Zhang, Xinbo; Li, Shukui

    2015-11-15

    Energetic structural material is a kind of materials that are inert under normal conditions but could produce exothermic chemical reaction when subjected to impact. This report shows a kind of energetic structural material of tungsten (W)-polytetrafluoroethylene (PTFE)-aluminum (Al) with density of 4.12 g/cm{sup 3}, excellent ductility and dynamic compressive strength of 96 MPa. Moreover, 50W-35PTFE-15Al (wt%) can exhibit a high reaction energy value of more than 2 times of TNT per unit mass and 5 times of TNT per unit volume, respectively, but with excellent insensitivity compared with traditional explosives. Under thermal conditions, the W-PTFE-Al composite can keep stable at 773 K. Under impact loading, when the strain rate up to ∼4820 s{sup −1} coupled with the absorbed energy per unit volume of 120 J/cm{sup 3}, deflagration occurs and combustion lasts for 500 μs. During impact compressive deformation, the PTFE matrix is elongated into nano-fibers, thus significantly increases the reaction activity of W-PTFE-Al composites. The nano-fiber structure is necessary for the reaction of W-PTFE-Al composites. The formation of PTFE nano-fibers must undergo severe plastic deformation, and therefore the W-PTFE-Al composites exhibit excellent insensitivity and safety. Furthermore, the reaction mechanisms of W-PTFE-Al composites in argon and in air are revealed.

  6. Triboelectrification-Induced Large Electric Power Generation from a Single Moving Droplet on Graphene/Polytetrafluoroethylene.

    PubMed

    Kwak, Sung Soo; Lin, Shisheng; Lee, Jeong Hwan; Ryu, Hanjun; Kim, Tae Yun; Zhong, Huikai; Chen, Hongsheng; Kim, Sang-Woo

    2016-08-23

    Recently, several reports have demonstrated that a moving droplet of seawater or ionic solution over monolayer graphene produces an electric power of about 19 nW, and this has been suggested to be a result of the pseudocapacitive effect between graphene and the liquid droplet. Here, we show that the change in the triboelectrification-induced pseudocapacitance between the water droplet and monolayer graphene on polytetrafluoroethylene (PTFE) results in a large power output of about 1.9 μW, which is about 100 times larger than that presented in previous research. During the graphene transfer process, a very strong negative triboelectric potential is generated on the surface of the PTFE. Positive and negative charge accumulation, respectively, occurs on the bottom and the top surfaces of graphene due to the triboelectric potential, and the negative charges that accumulate on the top surface of graphene are driven forward by the moving droplet, charging and discharging at the front and rear of the droplet.

  7. Polytetrafluoroethylene/TiO2 Composite Pellets as Sulfur Adsorbents for Pressure Oxidation Leaching of Chalcopyrite

    NASA Astrophysics Data System (ADS)

    Govindaiah, Patakamuri; Grundy, Mark; Guerra, Eduard; Choi, Yeonuk; Ye, Zhibin

    2015-04-01

    In this study, we report the use of polytetrafluoroethylene/titanium dioxide (PTFE/TiO2) composite pellets as sulfur adsorbents in the extraction of copper from chalcopyrite by pressure oxidation leaching. PTFE/TiO2 composites of various compositions were prepared by compression molding followed by pelletization. The mass percentage of TiO2 filler in the PTFE matrix was varied from 0 to 35 wt pct. With the use of the composite pellets, significant enhancements in copper leaching were observed, indicating their role as adsorbents for the adsorption of molten elemental sulfur. In particular, the enhancement in copper extraction was increasingly pronounced (from 75 to 89 pct) with the increase of the mass percentage of TiO2 in the composite pellets from 0 to 35 wt pct. This is reasoned to result from the loss of TiO2 domains from the pellet surface, which creates additional rough hydrophobic surface to better capture elemental sulfur. The composite pellet adsorbents show excellent reusability, with the performance well maintained for 10 leaching cycles. In addition, the effectiveness of composite adsorbents at different chalcopyrite pulp densities was also investigated.

  8. Ion-implanted polytetrafluoroethylene enhances Saccharomyces cerevisiae biofilm formation for improved immobilization.

    PubMed

    Tran, Clara T H; Kondyurin, Alexey; Hirsh, Stacey L; McKenzie, David R; Bilek, Marcela M M

    2012-11-01

    The surface of polytetrafluoroethylene (PTFE) was modified using plasma immersion ion implantation (PIII) with the aim of improving its ability to immobilize yeast. The density of immobilized cells on PIII-treated and -untreated PTFE was compared as a function of incubation time over 24 h. Rehydrated yeast cells attached to the PIII-treated PTFE surface more rapidly, with higher density, and greater attachment strength than on the untreated surface. The immobilized yeast cells were removed mechanically or chemically with sodium hydroxide and the residues left on the surfaces were analysed with Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS). The results revealed that the mechanism of cell attachment on both surfaces differs and a model is presented for each. Rapid attachment on the PIII-treated surface occurs through covalent bonds of cell wall proteins and the radicals on the treated surface. In contrast, on the untreated surface, only physisorbed molecules were found in the residue and lipids were more highly concentrated than proteins. The presence of lipids in the residue was found to be a consequence of damage to the plasma membrane during the rehydration process and the increased cell stress was also apparent by the amount of Hsp12 in the protein residue. The immobilized yeast cells on PIII-treated PTFE were found to be as active as yeast cells in suspension.

  9. Polytetrafluoroethylene Ingestion as a Way to Increase Food Volume and Hence Satiety Without Increasing Calorie Content.

    PubMed

    Naftalovich, Rotem; Naftalovich, Daniel; Greenway, Frank L

    2016-07-01

    Since satiety is largely due to stretch of the stomach and people tend to eat a consistent weight of food, increasing food volume and mass increases satiety. This can be achieved without increasing the calories of food by mixing food with a material that cannot be metabolized. Such a material should be inert, safe, resistant to stomach acid, lack taste, available in powder form, smooth, resistant to heat, and cost effective. Polytetrafluoroethylene (PTFE) is an ideal substance for this purpose. It is a soft plastic that is widely considered to be the most inert material known and is extremely stable. Animal feeding trials showed that rats fed a diet of 25% PTFE for 90 days had no signs of toxicity and that the rats lost weight. This article publishes the data from these subchronic animal feeding trials, reviews the relevant available literature, and hypothesizes that increasing the volume of food by mixing the food with PTFE powder at a ratio of 3 parts food to 1 part PTFE by volume will substantially improve satiety and reduce caloric consumption in people. PMID:26810925

  10. Audio and ultrasonic responses of laminated fluoroethylenepropylene and porous polytetrafluoroethylene films with different charge distributions

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoqing; Sessler, Gerhard M.; Xue, Yuan; Ma, Xingchen

    2016-05-01

    Laminated fluoropolymer films with a regular microstructure were made from compact fluoroethylenepropylene (FEP) and porous polytetrafluoroethylene (PTFE) using a process consisting of patterning and fusion bonding steps. The fabricated films were rendered piezoelectric via the contact charging or corona charging methods. The piezoelectric responses of such piezoelectret films were measured in the frequency range 100 Hz-100 kHz. The results show that the acoustic impedance of the FEP/PTFE films is around 0.014-0.030 MRayl. Dynamic piezoelectric d 33 coefficients of up to 500 pC N-1 were achieved at 100 Hz for these films. Microphones built with such films exhibit flat response curves in a broad frequency range if the diffraction effects are eliminated. Bonded films with all positive charges deposited in the porous PTFE layers show the best thermal stability: after annealing for 1100 min at 125 °C, the remaining d 33 at 1020 Hz is about 30% of the initial value, corresponding to 105 pC N-1, and it remains relatively stable at this temperature. This remarkable thermal stability has to be attributed to the fact that positive charges are more permanent in porous PTFE than in FEP. The entire charge distribution exhibits much better thermal stability than is achievable for customary polypropylene piezoelectrets.

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

    NASA Astrophysics Data System (ADS)

    Wang, Liu; Liu, Jinxu; Li, Shukui; Zhang, Xinbo

    2015-11-01

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

  12. The significant adhesion enhancement of Ag-polytetrafluoroethylene antibacterial coatings by using of molecular bridge

    NASA Astrophysics Data System (ADS)

    Guo, Ruijie; Yin, Guangda; Sha, Xiaojuan; Zhao, Qi; Wei, Liqiao; Wang, Huifang

    2015-06-01

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

  13. Electret Polyvinylidene Fluoride Nanofibers Hybridized by Polytetrafluoroethylene Nanoparticles for High-Efficiency Air Filtration.

    PubMed

    Wang, Shan; Zhao, Xinglei; Yin, Xia; Yu, Jianyong; Ding, Bin

    2016-09-14

    Airborne particulate matter (PM) pollution has become a severe environmental concern calling for electret fibrous materials with high filtration efficiency and low pressure drop. However, restraining the dissipation of the electric charges in service to ensure the stabilized electrostatic force of the fibers for effectively adsorbing particles is extremely important and also challenging. Herein, we report novel electret nanofibrous membranes with numerous charges and desirable charge stability using polyvinylidene fluoride (PVDF) as the matrix polymer and polytetrafluoroethylene nanoparticles (PTFE NPs) as an inspiring charge enhancer through the in situ charging technology of electrospinning. Benefiting from the employment of PTFE NPs and optimized injection energy, the fibrous membranes are endowed with elevated surface potentials from 0.42 to 3.63 kV and reduced decrement of charges from 75.4 to 17.5%, which contribute to the ameliorative stability of filtration efficiency. Significantly, an electret mechanism is proposed, while deepened depth of the energy level and incremental polarized dipole charges with increasing PTFE NP concentrations and injection energy have been confirmed through the measurement of open-circuit thermally stimulated discharge and surface potential decay. Ultimately, the resultant fibrous membrane exhibited a high filtration efficiency of 99.972%, a low pressure drop of 57 Pa, a satisfactory quality factor of 0.14 Pa(-1), and superior long-term service performance. The successful fabrication of such an intriguing material may provide a new approach for the design and development of electret materials for PM2.5 governance. PMID:27552028

  14. Optical characteristics of poly(tetrafluoroethylene) thin film prepared by a vacuum evaporation

    NASA Astrophysics Data System (ADS)

    Ohnishi, Yasutaka; Kita, Rio; Tsuchiya, Kazuyoshi; Iwamori, Satoru

    2016-02-01

    Poly(tetrafluoroethylene) (PTFE) thin films were deposited onto a glass slide substrate by a heat-resistance type vacuum evaporation apparatus due to changing the evaporation conditions. Transparency of the PTFE thin films prepared by the vacuum evaporation depended on the deposition conditions, i.e., temperatures of the basket, and distance between the evaporation source and substrate. To elucidate relationship between the molecular structure and transparency of the PTFE thin film prepared by the vacuum evaporation, chemical structures, crystallinity and thermophysical property were investigated. The chemical bonding state of the PTFE thin film prepared by the vacuum evaporation was almost the same as that of the pristine PTFE, however, the crystalinity was different. Although the pristine PTFE was crystal structure, the transparent evaporated thin film was estimated to be microcrystal structure. In addition, endothermic peaks in a differential scanning calorimeter (DSC) spectrum of the PTFE thin film were different from that of the pristine PTFE. These endothermic peaks of the PTFE thin film prepared by the vacuum evaporation shifted lower temperature compared to the pristine PTFE, which suggests that molecular weight of the PTFE thin film prepared by the vacuum evaporation decreased compared with that of the pristine PTFE.

  15. Audio and ultrasonic responses of laminated fluoroethylenepropylene and porous polytetrafluoroethylene films with different charge distributions

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoqing; Sessler, Gerhard M.; Xue, Yuan; Ma, Xingchen

    2016-05-01

    Laminated fluoropolymer films with a regular microstructure were made from compact fluoroethylenepropylene (FEP) and porous polytetrafluoroethylene (PTFE) using a process consisting of patterning and fusion bonding steps. The fabricated films were rendered piezoelectric via the contact charging or corona charging methods. The piezoelectric responses of such piezoelectret films were measured in the frequency range 100 Hz–100 kHz. The results show that the acoustic impedance of the FEP/PTFE films is around 0.014–0.030 MRayl. Dynamic piezoelectric d 33 coefficients of up to 500 pC N‑1 were achieved at 100 Hz for these films. Microphones built with such films exhibit flat response curves in a broad frequency range if the diffraction effects are eliminated. Bonded films with all positive charges deposited in the porous PTFE layers show the best thermal stability: after annealing for 1100 min at 125 °C, the remaining d 33 at 1020 Hz is about 30% of the initial value, corresponding to 105 pC N‑1, and it remains relatively stable at this temperature. This remarkable thermal stability has to be attributed to the fact that positive charges are more permanent in porous PTFE than in FEP. The entire charge distribution exhibits much better thermal stability than is achievable for customary polypropylene piezoelectrets.

  16. Fluoropolymer Films Deposited by RF Plasma Sputtering of Polytetrafluoroethylene Using Inert Gases

    NASA Technical Reports Server (NTRS)

    Golub, Morton A.; Wydeven, Theodore; Kliss, Mark (Technical Monitor)

    1998-01-01

    The FT-IR (Fourier Transform Infrared), UV (Ultraviolet) and XPS (X Ray Photoelectron Spectroscopy) spectra of fluoropolymer films (SPTFE) deposited by rf (radio frequency) plasma sputtering of polytetrafluoroethylene (PTFE), using Ne, Kr and Xe as sputtering gases, were obtained and compared with prior spectra for SPTFE formed using He and Ar. The F/C (fluorine / carbon) ratios for SPTFE films (1.44-1.55), obtained at a rf power of 10 W, were essentially the same for all five rare gases, there being no trend of decreasing fluorine content in the SPTFE product with increasing atomic weight of the sputtering gas - contrary to the momentum transfer notion advanced by M. E. Ryan, et al. Increasing rf power from 10 to 50 W resulted in successively lower F/C ratios for SPTFE (e.g., from 1.55 to 1.21 in the case of Xe plasma-sputtered PTFE), accompanied by sputtering of the glass reactor and deposition of fragments of sodium aluminum silicate occurring at 40 W and above. In order to achieve a "Teflon-like" SPTFE structure (i.e., products with as high a F/C ratio as possible) in a given plasma reactor, an optimum rf power must be found, which in the present case was approximately 10 W.

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

    PubMed Central

    Wang, Shibo; Niu, Chengchao

    2016-01-01

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

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

    PubMed

    Wang, Shibo; Niu, Chengchao

    2016-01-01

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

  19. Wet Chemistry and Peptide Immobilization on Polytetrafluoroethylene for Improved Cell-adhesion.

    PubMed

    Gabriel, Matthias; Niederer, Kerstin; Frey, Holger

    2016-01-01

    Endowing materials surface with cell-adhesive properties is a common strategy in biomaterial research and tissue engineering. This is particularly interesting for already approved polymers that have a long standing use in medicine because these materials are well characterized and legal issues associated with the introduction of newly synthesized polymers may be avoided. Polytetrafluoroethylene (PTFE) is one of the most frequently employed materials for the manufacturing of vascular grafts but the polymer lacks cell adhesion promoting features. Endothelialization, i.e., complete coverage of the grafts inner surface with a confluent layer of endothelial cells is regarded key to optimal performance, mainly by reducing thrombogenicity of the artificial interface. This study investigates the growth of endothelial cells on peptide-modified PTFE and compares these results to those obtained on unmodified substrate. Coupling with the endothelial cell adhesive peptide Arg-Glu-Asp-Val (REDV) is performed via activation of the fluorin-containing polymer using the reagent sodium naphthalenide, followed by subsequent conjugation steps. Cell culture is accomplished using Human Umbilical Vein Endothelial Cells (HUVECs) and excellent cellular growth on peptide-immobilized material is demonstrated over a two-week period. PMID:27584937

  20. Functionalized expanded porphyrins

    DOEpatents

    Sessler, Jonathan L; Pantos, Patricia J

    2013-11-12

    Disclosed are functionalized expanded porphyrins that can be used as spectrometric sensors for high-valent actinide cations. The disclosed functionalized expanded porphyrins have the advantage over unfunctionalized systems in that they can be immobilized via covalent attachment to a solid support comprising an inorganic or organic polymer or other common substrates. Substrates comprising the disclosed functionalized expanded porphyrins are also disclosed. Further, disclosed are methods of making the disclosed compounds (immobilized and free), methods of using them as sensors to detect high valent actinides, devices that comprise the disclosed compounds, and kits.

  1. Prelining of polytetrafluoroethylene grafts with cultured human endothelial cells isolated from varicose veins.

    PubMed

    Leseche, G; Bikfalvi, A; Dupuy, E; Tobelem, G; Andreassian, B; Caen, J

    1989-01-01

    Prelining graft material with autologous functioning endothelial cells might be one of the ultimate requirements to obtain a biocompatible surface. Accordingly, endothelial cells from stripped varicose veins were enzymatically harvested and grown on a fibronectin matrix. Proliferation was investigated in defined medium supplemented with various concentrations of endothelial cell growth supplement (ECGS) (25, up to 150 micrograms/ml) and heparin (10(-8), up to 10(-5)mol/L): optimal growth required both 150 micrograms/ml of ECGS and 10(-5)mol/L heparin. Under these conditions, cell culture achieved cell densities at a confluence of 1.2 +/- 1.1 10(5) cells/cm2 with a doubling time of 1 day. During subcultivation cultured cells consistently exhibited characteristic cobblestone morphology and immunofluorescent staining for factor VIII-related antigen, whereas prostacyclin production determined by enzyme-linked immunosorbent assay for 6-keto-prostaglandin F1 alpha reached 21.1 +/- 1.2 ng/10(6) cells after 15-minute stimulation with 1 U/ml of thrombin. Heparin-containing culture medium-endothelial cell interactions were particularly studied, and with iodine 125-heparin, binding was demonstrated with an apparent dissociation constant (Kd) of 0.36 +/- 0.04 mumol/L. A cold storage technique at -80 degrees C was sought, and freezed cells were used to coat in vitro polytetrafluoroethylene grafts. Protein-treated material allowed cell attachment and growth to a confluent monolayer as assayed by light and scanning electron microscopy. These data validate the feasibility of prelining grafts in vitro with autologous functioning endothelial cells. This approach may be useful in improving the performance of small-caliber vascular grafts according to prostacyclin production and surface-bound heparin of these cells.

  2. Fluoropolymer Films Deposited by Argon Ion-Beam Sputtering of Polytetrafluoroethylene

    NASA Technical Reports Server (NTRS)

    Golub, Morton A.; Banks, Bruce A.; Kliss, Mark (Technical Monitor)

    1998-01-01

    The FT-IR, XPS and UV spectra of fluoropolymer films (SPTFE-I) deposited by argon ion-beam sputtering of polytetrafluoroethylene (PTFE) were obtained and compared with prior corresponding spectra of fluoropolymer films (SPTFE-P) deposited by argon rf plasma sputtering of PTFE. Although the F/C ratios for SPTFE-I and -P (1.63 and 1.51) were similar, their structures were quite different in that there was a much higher concentration of CF2 groups in SPTFE-I than in SPTFE-P, ca. 61 and 33% of the total carbon contents, respectively. The FT-IR spectra reflect that difference, that for SPTFE-I showing a distinct doublet at 1210 and 1150 per centimeter while that for SPTFE-P presents a broad, featureless band at ca. 1250 per centimeter. The absorbance of the 1210-per centimeter band in SPTFE-I was proportional to the thickness of the film, in the range of 50-400 nanometers. The SPTFE-I was more transparent in the UV than SPTFE-P at comparable thickness. The mechanism for SPTFE-I formation likely involves "chopping off" of oligomeric segments of PTFE as an accompaniment to "plasma" polymerization of TFE monomer or other fluorocarbon fragments generated in situ from PTFE on impact with energetic Ar ions. Data are presented for SPTFE-I deposits and the associated Ar(+) bombarded PTFE targets where a fresh target was used for each run or a single target was used for a sequence of runs.

  3. Comparison of a New Polytetrafluoroethylene-Covered Metallic Stent to a Noncovered Stent in Canine Ureters

    SciTech Connect

    Chung, Hwan-Hoon Lee, Seung Hwa; Cho, Sung Bum; Park, Hong Suk; Kim, Young Sik; Kang, Byung Chul; Frisoli, Joan K.; Razavi, Mahmood K.

    2008-05-15

    The aim of this study was to determine the feasibility of using a newly designed polytetrafluoroethylene (PTFE)-covered metallic stent in the ureter by comparing its effectiveness with that of the noncovered stent in a canine model. We placed 14 stents in the ureters of seven mongrel dogs that weighed 30-40 kg each. The covered and noncovered stents were deployed in the right and left ureters, respectively, of six dogs. In the seventh dog, a covered stent and a double-J catheter were inserted in the right ureter, and a covered stent only was inserted in the left ureter. The first six dogs were sacrificed at 5, 10, and 15 weeks after deployment of the stents (two for each follow-up period), and the seventh dog was sacrificed at 30 weeks. There was no migration or poor expansion of any of the stents observed on plain radiography. On intravenous pyelogram and retrograde pyelogram, all of the covered stents at each follow-up period had patent lumens at the stented segments without hydronephrosis, and the passage of contrast material through it was well preserved. The noncovered stents in the dogs sacrificed at 5 and 10 weeks and one of the two dogs sacrificed at 15 weeks showed near-complete occlusion of the stent lumen due to ingrowth of the soft tissue, and severe hydronephrosis was also noted. The noncovered stent in the other dog sacrificed at 15 weeks showed the passage of contrast material without hydronephrosis, but the lumen of the stent was still nearly occluded by the soft tissue. There was no evidence of hydronephrosis or passage disturbance of the contrast material in both ureters of the dog sacrificed at 30 weeks. We conclude that the newly designed PTFE-covered stent effectively prevented the luminal occlusion caused by urothelial hyperplasia compared to the near-total occlusion of the noncovered stents, and no migration of the covered stents was noted.

  4. Theme: The Expanded Mission.

    ERIC Educational Resources Information Center

    Finley, Eddy; And Others

    1991-01-01

    This theme issue covers the following topics: modernization of agricultural education, an expanded mission for the field, community development, a national presence for agricultural education, revising curriculum, and interesting students in new careers in agriculture. (SK)

  5. Optimization of expander plants

    SciTech Connect

    Wang, W.B.

    1985-01-01

    A computer program that uses the Tomich technique to solve multistage, multi-feed distillation problems was modified. The MSEQ method was utilized to generate initial temperature and vapor rate profiles. The modified fractionator program coupled with the MSEQ method was used to generate required rigorous data for expander-plant demethanizer splits. Furthermore, a shortcut method was developed to facilitate expander process simulation. Calculated demethanizer results from a simulation were compared with a commercial program with good agreement. The results from the shortcut method were in good agreement with rigorous calculations. Computer simulations were made for four different natural gases ranging from lean to rich in liquefiable hydrocarbons for various turboexpander plant processes. These processes included self-refrigerated expander process with/without external refrigeration, and with/without demethanizer heat recovery. Only lean gases can be utilized in the self-refrigerated expander process with high ethane recovery. While the use of external refrigeration in conjunction with the expander process can reduce overall horsepower requirements, it may not be economical to do so. In general, the processing should be carried out at the highest practical processing pressure. The use of demethanizer heat recovery is an efficient method to reduce both refrigeration horsepower and recompression energy requirements. This work emphasizes high ethane recovery. Further study of expander processes emphasizing ethane rejection is advisable.

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

    SciTech Connect

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

    2007-02-02

    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.

  7. Silicon microfabricated beam expander

    SciTech Connect

    Othman, A. Ibrahim, M. N.; Hamzah, I. H.; Sulaiman, A. A.; Ain, M. F.

    2015-03-30

    The feasibility design and development methods of silicon microfabricated beam expander are described. Silicon bulk micromachining fabrication technology is used in producing features of the structure. A high-precision complex 3-D shape of the expander can be formed by exploiting the predictable anisotropic wet etching characteristics of single-crystal silicon in aqueous Potassium-Hydroxide (KOH) solution. The beam-expander consist of two elements, a micromachined silicon reflector chamber and micro-Fresnel zone plate. The micro-Fresnel element is patterned using lithographic methods. The reflector chamber element has a depth of 40 µm, a diameter of 15 mm and gold-coated surfaces. The impact on the depth, diameter of the chamber and absorption for improved performance are discussed.

  8. An automated baseline correction protocol for infrared spectra of atmospheric aerosols collected on polytetrafluoroethylene (Teflon) filters

    NASA Astrophysics Data System (ADS)

    Kuzmiakova, Adele; Dillner, Ann M.; Takahama, Satoshi

    2016-06-01

    A growing body of research on statistical applications for characterization of atmospheric aerosol Fourier transform infrared (FT-IR) samples collected on polytetrafluoroethylene (PTFE) filters (e.g., Russell et al., 2011; Ruthenburg et al., 2014) and a rising interest in analyzing FT-IR samples collected by air quality monitoring networks call for an automated PTFE baseline correction solution. The existing polynomial technique (Takahama et al., 2013) is not scalable to a project with a large number of aerosol samples because it contains many parameters and requires expert intervention. Therefore, the question of how to develop an automated method for baseline correcting hundreds to thousands of ambient aerosol spectra given the variability in both environmental mixture composition and PTFE baselines remains. This study approaches the question by detailing the statistical protocol, which allows for the precise definition of analyte and background subregions, applies nonparametric smoothing splines to reproduce sample-specific PTFE variations, and integrates performance metrics from atmospheric aerosol and blank samples alike in the smoothing parameter selection. Referencing 794 atmospheric aerosol samples from seven Interagency Monitoring of PROtected Visual Environment (IMPROVE) sites collected during 2011, we start by identifying key FT-IR signal characteristics, such as non-negative absorbance or analyte segment transformation, to capture sample-specific transitions between background and analyte. While referring to qualitative properties of PTFE background, the goal of smoothing splines interpolation is to learn the baseline structure in the background region to predict the baseline structure in the analyte region. We then validate the model by comparing smoothing splines baseline-corrected spectra with uncorrected and polynomial baseline (PB)-corrected equivalents via three statistical applications: (1) clustering analysis, (2) functional group quantification

  9. Superhydrophobic and oleophilic open-cell foams from fibrillar blends of polypropylene and polytetrafluoroethylene.

    PubMed

    Rizvi, Ali; Chu, Raymond K M; Lee, Jung H; Park, Chul B

    2014-12-10

    Effective removal of oils from water is of global significance for environmental protection. In this study, we investigate the hydrophobicity and oleophilicity of open-cell polymer foams prepared in a continuous and scalable extrusion process. The material used to prepare the open-cell foams is a fibrillar blend of polypropylene (PP) and polytetrafluoroethylene (PTFE). Scanning electron microscopy (SEM) images of the morphology of the PP/PTFE fibrillar blend reveal that the PTFE has a fibrillar morphology in the PP matrix. SEM micrograph of the extruded foam shows the formation of an interconnected open-cell structure. Using nitrogen pycnometry, the open-cell content is estimated to be 97.7%. A typical bulk density of the open-cell foam is measured to be about 0.07 g cm(-3) corresponding to a void fraction of 92%. Thus, a large three-dimensional space is made available for oil storage. A drop of water on the cross-section of the extruded open-cell foam forms a contact angle of 160° suggesting that the open-cell foam exhibits superhydrophobicity. The open-cell foam can selectively absorb various petroleum products, such as octane, gasoline, diesel, kerosene, light crude oil, and heavy crude oil from water and the uptake capacities range from about 5 to 24 g g(-1). The uptake kinetics can be enhanced by exposing the open-cell foam to high intensity ultrasound which increases the surface porosity of the thin, impervious, foam "skin" layer. The reusability of the foam can be improved by using a matrix polymer which demonstrates superior elastic properties and prevents the foams from undergoing a large permanent deformation upon compression to "squeeze out" the oil. For example, when the PP homopolymer matrix is replaced with a PP random copolymer, the permanent deformation for 10 compressive cycles is reduced from about 30% to 10%. To the best of our knowledge, these PP-based open-cell foams outperform PP-based absorbents conventionally used for oil-spill cleanup

  10. Elucidation of atomic scale mechanisms for polytetrafluoroethylene tribology using molecular dynamics simulation

    NASA Astrophysics Data System (ADS)

    Barry, Peter R.

    Polytetrafluoroethylene (PTFE) is a polymer that has been widely exploited commercially as a result of its low friction, 'non-stick' properties. The polymer has found usage as 'non-stick,' chemically resistant coatings for bearings, valves, rollers and pipe linings with applications in industries ranging from food and chemical processing to construction, automotive and aerospace. The major drawback of PTFE in low friction applications involves its excessive wear rate. For decades, scientists and engineers have sought to improve the polymer's wear resistance while maintaining its low sliding friction by reinforcing the polymer matrix with a host of filler materials ranging from fibril to particulate. In this study, a different approach is taken in which the atomic scale phenomena between two crystalline PTFE surfaces in sliding contact are examined. The goal is to obtain atomic-level insights into PTFE's low friction and high wear rate to aid in the designing of effective polymer based tribological composites for extreme condition applications. To accomplish this, several tribological conditions were varied. These included sliding direction of the two polymer surfaces with respect to their chain alignment, sliding velocity, degree of crystalline phase rigidity, interfacial contact pressure, sample temperature and the presence of fluorocarbon fluids between the two crystalline PTFE surfaces. From these studies, it was found that crystalline PTFE-PTFE sliding demonstrates friction anisotropy. Low friction and molecular wear was observed when sliding in the direction of the chain alignment with high friction and wear behavior dominating when sliding in a direction perpendicular to the chain alignment. For the range of cross-link density (average linear density of 6.2 to 11.1 A) and sliding rate (5 m/s to 20 m/s) explored, a significant change in friction behavior or wear mechanisms was not observed. Under conditions of increased normal load or low temperature however

  11. Expander plant design

    SciTech Connect

    Not Available

    1986-01-01

    Expander plant design is iterative. In order to calculate an answer it is necessary to have an answer to start with. Consequently, the starting point for a final design is a function of the experience level of the designer and his personal preference. This paper assumes that the designer has no experience in expander plant design and concentrates on providing methods for assuming an answer that will be close enough to the final answer that the design can be done with a minimum number of iterations. For illustration, several typical process designs are presented.

  12. Nanoporous Polytetrafluoroethylene/Silica Composite Separator as a High-Performance All-Vanadium Redox Flow Battery Membrane

    SciTech Connect

    Wei, Xiaoliang; Nie, Zimin; Luo, Qingtao; Li, Bin; Chen, Baowei; Simmons, Kevin L.; Sprenkle, Vincent L.; Wang, Wei

    2013-09-02

    Driven by the motivation of searching for low-cost membrane alternatives, a novel nanoporous polytetrafluoroethylene/silica composite separator has been prepared and evaluated for its use in all-vanadium mixed-acid redox flow battery. This separator consisting of silica particles enmeshed in a polytetrafluoroethylene fibril matrix has no ion exchange capacity and is featured with unique nanoporous structures, which function as the ion transport channels in redox flow battery operation, with an average pore size of 38nm and a porosity of 48%. This separator has produced excellent electrochemical performance in the all-vanadium mixed-acid system with energy efficiency delivery comparable to Nafion membrane and superior rate capability and temperature tolerance. The separator also demonstrates an exceptional capacity retention capability over extended cycling, offering additional operational latitude towards conveniently mitigating the capacity decay that is inevitable for Nafion. Because of the inexpensive raw materials and simple preparation protocol, the separator is particularly low-cost, estimated to be at least an order of magnitude more inexpensive than Nafion. Plus the proven chemical stability due to the same backbone material as Nafion, this separator possesses a good combination of critical membrane requirements and shows great potential to promote market penetration of the all-vanadium redox flow battery by enabling significant reduction of capital and cycle costs.

  13. Miniaturized Dual Band Multislotted Patch Antenna on Polytetrafluoroethylene Glass Microfiber Reinforced for C/X Band Applications

    PubMed Central

    Islam, M. T.; Samsuzzaman, M.

    2014-01-01

    This paper introduces a new configuration of compact, triangular- and diamond-slotted, microstrip-fed, low-profile antenna for C/X band applications on polytetrafluoroethylene glass microfiber reinforced material substrate. The antenna is composed of a rectangular-shaped patch containing eight triangles and two diamond-shaped slots and an elliptical-slotted ground plane. The rectangular-shaped patch is obtained by cutting two diamond slots in the middle of the rectangular patch, six triangular slots on the left and right side of the patch, and two triangular slots on the up and down side of the patch. The slotted radiating patch, the elliptical-slotted ground plane, and the microstrip feed enable the matching bandwidth to be widened. A prototype of the optimized antenna was fabricated on polytetrafluoroethylene glass microfiber reinforced material substrate using LPKF prototyping machine and investigated to validate the proposed design. The simulated results are compared with the measured data, and good agreement is achieved. The proposed antenna offers fractional bandwidths of 13.69% (7.78–8.91 GHz) and 10.35% (9.16–10.19 GHz) where S11 < −10 dB at center frequencies of 8.25 GHz and 9.95 GHz, respectively, and relatively stable gain, good radiation efficiency, and omnidirectional radiation patterns in the matching band. PMID:24987742

  14. Miniaturized dual band multislotted patch antenna on polytetrafluoroethylene glass microfiber reinforced for C/X band applications.

    PubMed

    Islam, M T; Samsuzzaman, M

    2014-01-01

    This paper introduces a new configuration of compact, triangular- and diamond-slotted, microstrip-fed, low-profile antenna for C/X band applications on polytetrafluoroethylene glass microfiber reinforced material substrate. The antenna is composed of a rectangular-shaped patch containing eight triangles and two diamond-shaped slots and an elliptical-slotted ground plane. The rectangular-shaped patch is obtained by cutting two diamond slots in the middle of the rectangular patch, six triangular slots on the left and right side of the patch, and two triangular slots on the up and down side of the patch. The slotted radiating patch, the elliptical-slotted ground plane, and the microstrip feed enable the matching bandwidth to be widened. A prototype of the optimized antenna was fabricated on polytetrafluoroethylene glass microfiber reinforced material substrate using LPKF prototyping machine and investigated to validate the proposed design. The simulated results are compared with the measured data, and good agreement is achieved. The proposed antenna offers fractional bandwidths of 13.69% (7.78-8.91 GHz) and 10.35% (9.16-10.19 GHz) where S11 < -10 dB at center frequencies of 8.25 GHz and 9.95 GHz, respectively, and relatively stable gain, good radiation efficiency, and omnidirectional radiation patterns in the matching band. PMID:24987742

  15. Expanding Student Assessment Opportunities.

    ERIC Educational Resources Information Center

    Bartscher, Beth; Carter, Andrea; Lawlor, Anna; McKelvey, Barbara

    This paper describes an approach for expanding assessment opportunities for students to demonstrate their understanding of content. The targeted population consisted of elementary and junior high school students in two schools in a growing middle-class community in north central Illinois. The elementary school enrolled 467 students and the junior…

  16. Expanded Roles for HRD.

    ERIC Educational Resources Information Center

    1998

    This document contains three papers from a symposium on expanded roles for human resource development (HRD). "The Roles of Consultants in Gainsharing Firms: Empirical Results" (Eunsang Cho, Gary N. McLean) reports findings that consultants are moderately involved at the separation, preparation, evaluation, and design stages and have low…

  17. ExpandED Options: Learning beyond High School Walls

    ERIC Educational Resources Information Center

    ExpandED Schools, 2014

    2014-01-01

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

  18. X-Ray Photoelectron Spectroscopy Study of the Effect of Hydrocarbon Contamination on Poly(Tetrafluoroethylene) Exposed to a Nitrogen Plasma

    NASA Technical Reports Server (NTRS)

    Golub, Morton A.; Lopata, Eugene S.; Finney, Lorie S.

    1993-01-01

    In this note, we show that X-ray photoelectron Spectroscopy (XPS) data and the changes in surface properties attending exposure of poly(tetrafluoroethylene) (PTFE) films to a nitrogen plasma can likewise be misinterpreted when the interfering role of minor surface hydrocarbon contamination is not taken into account.

  19. Expandable LED array interconnect

    DOEpatents

    Yuan, Thomas Cheng-Hsin; Keller, Bernd

    2011-03-01

    A light emitting device that can function as an array element in an expandable array of such devices. The light emitting device comprises a substrate that has a top surface and a plurality of edges. Input and output terminals are mounted to the top surface of the substrate. Both terminals comprise a plurality of contact pads disposed proximate to the edges of the substrate, allowing for easy access to both terminals from multiple edges of the substrate. A lighting element is mounted to the top surface of the substrate. The lighting element is connected between the input and output terminals. The contact pads provide multiple access points to the terminals which allow for greater flexibility in design when the devices are used as array elements in an expandable array.

  20. Grazing incidence beam expander

    SciTech Connect

    Akkapeddi, P.R.; Glenn, P.; Fuschetto, A.; Appert, Q.; Viswanathan, V.K.

    1985-01-01

    A Grazing Incidence Beam Expander (GIBE) telescope is being designed and fabricated to be used as an equivalent end mirror in a long laser resonator cavity. The design requirements for this GIBE flow down from a generic Free Electron Laser (FEL) resonator. The nature of the FEL gain volume (a thin, pencil-like, on-axis region) dictates that the output beam be very small. Such a thin beam with the high power levels characteristic of FELs would have to travel perhaps hundreds of meters or more before expanding enough to allow reflection from cooled mirrors. A GIBE, on the other hand, would allow placing these optics closer to the gain region and thus reduces the cavity lengths substantially. Results are presented relating to optical and mechanical design, alignment sensitivity analysis, radius of curvature analysis, laser cavity stability analysis of a linear stable concentric laser cavity with a GIBE. Fabrication details of the GIBE are also given.

  1. Discovering the Expanding Universe

    NASA Astrophysics Data System (ADS)

    Nussbaumer, Harry; Bieri, Lydia; Sandage, Foreword by Allan

    2009-03-01

    Acknowledgments; Foreword; 1. Introduction; 2. Cosmological concepts at the end of the Middle Ages; 3. Nebulae as a new astronomical phenomenon; 4. On the construction of the Heavens; 5. Island universes turn into astronomical facts: a universe of galaxies; 6. The early cosmology of Einstein and de Sitter; 7. The dynamical universe of Friedmann; 8. Redshifts: how to reconcile Slipher and de Sitter?; 9. Lemaître discovers the expanding universe; 10. Hubble's contribution of 1929; 11. The breakthrough for the expanding universe; 12. Hubble's anger about de Sitter; 13. Robertson and Tolman join the game; 14. The Einstein-de Sitter universe; 15. Are Sun and Earth older than the universe?; 16. In search of alternative tracks; 17. The seed for the Big Bang; 18. Summary and Postscript; Appendix; References; Index.

  2. Radiation-induced graft polymermization of acrylamide onto poly(tetrafluoroethylene/ Hexaflouropropylene/vinylidene fluoride) (TFB) films

    NASA Astrophysics Data System (ADS)

    Dessouki, A. M.; Taher, N. H.; El-Boohy, H. A.

    Radiation-induced graft polymerization of acrylamide (AAm) onto poly(tetrafluoroethylene/ hexafluoropropylene/vinylidene fluoride) (TFB) films has been investigated. The appropriate reaction conditions at which the graft polymerization was carried out successfully were selected. It was observed that the grafting process was enhanced remarkably by using distilled water as diluent. In this grafting system ammonium ferrous sulphate (Mohr's salt) was used as inhibitor to minimize the homopolymerization of AAm and the suitable concentration of such inhibitor was found to be 3.5wt%. The dependence of the grafting rate on the monomer concentration was calculated to be 2.8 order. Some properties of the grafted films such as water uptake, electrical conductivity, mechanical properties and chemical and thermal stability were investigated. An improvement in these properties was observed which makes possible the use of these membranes in some practical applications.

  3. Permanent hydrophilization of outer and inner surfaces of polytetrafluoroethylene tubes using ambient air plasma generated by surface dielectric barrier discharges

    SciTech Connect

    Pavliňák, D.; Galmiz, O.; Zemánek, M.; Brablec, A.; Čech, J.; Černák, M.

    2014-10-13

    We present an atmospheric pressure ambient air plasma technique developed for technically simple treatment of inner and/or outer surfaces of plastic tubes and other hollow dielectric bodies. It is based on surface dielectric barrier discharge generating visually diffuse plasma layers along the treated dielectric surfaces using water-solution electrodes. The observed visual uniformity and measured plasma rotational and vibrational temperatures of 333 K and 2350 K indicate that the discharge can be readily applied to material surface treatment without significant thermal effect. This is exemplified by the obtained permanent surface hydrophilization of polytetrafluoroethylene tubes related to the replacement of a high fraction (more than 80%) of the surface fluorine determined by X-ray photoelectron spectroscopy. A tentative explanation of the discharge mechanism based on high-speed camera observations and the discharge current and voltage of measurements is outlined.

  4. Thermal stability of electron-irradiated poly(tetrafluoroethylene) - X-ray photoelectron and mass spectroscopic study

    NASA Technical Reports Server (NTRS)

    Wheeler, Donald R.; Pepper, Stephen V.

    1990-01-01

    Polytetrafluoroethylene (PTFE) was subjected to 3 keV electron bombardment and then heated in vacuum to 300 C. The behavior of the material as a function of radiation dose and temperature was studied by X-ray photoelectron spectroscopy (XPS) of the surface and mass spectroscopy of the species evolved. Lightly damaged material heated to 300 C evolved saturated fluorocarbon species, whereas unsaturated fluorocarbon species were evolved from heavily damaged material. After heating the heavily damaged material, those features in the XPS spectrum that were associated with damage diminished, giving the appearance that the radiation damage had annealed. The observations were interpreted by incorporating mass transport of severed chain fragments and thermal decomposition of severely damaged material into the branched and cross-linked network model of irradiated PTFE. The apparent annealing of the radiation damage was due to covering of the network by saturated fragments that easily diffused through the decomposed material to the surface region upon heating.

  5. Effect of through-plane polytetrafluoroethylene distribution in gas diffusion layers on performance of proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Ito, Hiroshi; Iwamura, Takuya; Someya, Satoshi; Munakata, Tetsuo; Nakano, Akihiro; Heo, Yun; Ishida, Masayoshi; Nakajima, Hironori; Kitahara, Tatsumi

    2016-02-01

    This experimental study identifies the effect of through-plane polytetrafluoroethylene (PTFE) distribution in gas diffusion backing (GDB) on the performance of proton exchange membrane fuel cells (PEMFC). PTFE-drying under vacuum pressure created a relatively uniform PTFE distribution in GDB compared to drying under atmospheric pressure. Carbon paper samples with different PTFE distributions due to the difference in drying conditions were prepared and used for the cathode gas diffusion layer (GDL) of PEMFCs. Also investigated is the effect of MPL application on the performance for those samples. The current density (i) - voltage (V) characteristics of these PEMFCs measured under high relative humidity conditions clearly showed that, with or without MPL, the cell using the GDL with PTFE dried under vacuum condition showed better performance than that dried under atmospheric condition. It is suggested that this improved performance is caused by the efficient transport of liquid water through the GDB due to the uniform distribution of PTFE.

  6. Anisotropic pyrochemical microetching of poly(tetrafluoroethylene) initiated by synchrotron radiation-induced scission of molecule bonds

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Akinobu; Kido, Hideki; Ukita, Yoshiaki; Kishihara, Mitsuyoshi; Utsumi, Yuichi

    2016-02-01

    We developed a process for micromachining polytetrafluoroethylene (PTFE): anisotropic pyrochemical microetching induced by synchrotron X-ray irradiation. X-ray irradiation was performed at room temperature. Upon heating, the irradiated PTFE substrates exhibited high-precision features. Both the X-ray diffraction peak and Raman signal from the irradiated areas of the substrate decreased with increasing irradiation dose. The etching mechanism is speculated as follows: X-ray irradiation caused chain scission, which decreased the number-average degree of polymerization. The melting temperature of irradiated PTFE decreased as the polymer chain length decreased, enabling the treated regions to melt at a lower temperature. The anisotropic pyrochemical etching process enabled the fabrication of PTFE microstructures with higher precision than simultaneously heating and irradiating the sample.

  7. Dynamics of changes in the colored form of spiroantrooxazine incorporated into polytetrafluoroethylene F-42 in a supercritical carbon dioxide medium

    NASA Astrophysics Data System (ADS)

    Kopylov, A. S.; Glagolev, N. N.; Timashev, P. S.; Cherkasova, A. V.; Timashev, S. F.; Solov'eva, A. B.

    2015-09-01

    It is shown that the incorporation of spiroantrooxazine (SAO), which has pronounced photochromic properties, into polytetrafluoroethylene F-42 in supercritical carbon dioxide medium leads to the formation of metastable colored photochromic states of different structure. In the subsequent relaxation of the polymer-SAO system, these states give rise to the most thermodynamically stable isomeric form of SAO for the given system. The kinetics of these reactions is analyzed in supercritical CO2 medium and after placing the test sample in air upon the formation of the unstable colored form of the photochromic molecule in the polymeric matrix. It is noted that in these cases, comparison of the rate constants of relaxation transitions allows us to numerically assess how the matrix plasticization by carbon dioxide affects the formation of photochromic colored states and the relaxation reorganization of the photochromic metastable forms.

  8. Expanded criteria donors.

    PubMed

    Feng, Sandy; Lai, Jennifer C

    2014-08-01

    The greatest challenge facing liver transplantation today is the shortage of donor livers. Demand far exceeds supply, and this deficit has driven expansion of what is considered an acceptable organ. The evolving standard has not come without costs, however, as each new frontier of expanded donor quality (i.e., advancing donor age, donation after cardiac death, and split liver) may have traded wait-list for post-transplant morbidity and mortality. This article delineates the nature and severity of risk associated with specific deceased donor liver characteristics and recommends strategies to maximally mitigate these risks. PMID:25017080

  9. Expandable pattern casting research

    NASA Astrophysics Data System (ADS)

    1993-09-01

    The Expandable Pattern Casting (EPC) Process is a developing foundry technology that allows designers the opportunity to consolidate parts, reduce machining, and minimize assembly operations. An air gauging system was developed for measuring foam patterns; exact shrinkage depended on type and density of the foam. Compaction studies showed that maximum sand densities in cavities and under overhangs are achieved with vibrational amplitudes 0.001-0.004 in., and that sand moved most freely within a few inches of the top free surface. Key to complete mold filling while minimizing casting defects lies in removing the foam decomposition products. The most precise iron castings were made by EPC in four commercial EPC foundries, with attention paid to molding and compaction. EP cast 60-45-12 ductile iron had yield strengths, ultimate strengths, and elastic modulus similar to conventionally cast ductile iron cast from the same ladle.

  10. Expanding hollow metal rings

    DOEpatents

    Peacock, Harold B.; Imrich, Kenneth J.

    2009-03-17

    A sealing device that may expand more planar dimensions due to internal thermal expansion of a filler material. The sealing material is of a composition such that when desired environment temperatures and internal actuating pressures are reached, the sealing materials undergoes a permanent deformation. For metallic compounds, this permanent deformation occurs when the material enters the plastic deformation phase. Polymers, and other materials, may be using a sealing mechanism depending on the temperatures and corrosivity of the use. Internal pressures are generated by either rapid thermal expansion or material phase change and may include either liquid or solid to gas phase change, or in the gaseous state with significant pressure generation in accordance with the gas laws. Sealing material thickness and material composition may be used to selectively control geometric expansion of the seal such that expansion is limited to a specific facing and or geometric plane.

  11. Mechanically expandable annular seal

    DOEpatents

    Gilmore, Richard F.

    1983-01-01

    A mechanically expandable annular reusable seal assembly to form an annular hermetic barrier between two stationary, parallel, and planar containment surfaces. A rotatable ring, attached to the first surface, has ring wedges resembling the saw-tooth array of a hole saw. Matching seal wedges are slidably attached to the ring wedges and have their motion restricted to be perpendicular to the second surface. Each seal wedge has a face parallel to the second surface. An annular elastomer seal has a central annular region attached to the seal wedges' parallel faces and has its inner and outer circumferences attached to the first surface. A rotation of the ring extends the elastomer seal's central region perpendicularly towards the second surface to create the fluidtight barrier. A counterrotation removes the barrier.

  12. Mechanically expandable annular seal

    DOEpatents

    Gilmore, R.F.

    1983-07-19

    A mechanically expandable annular reusable seal assembly to form an annular hermetic barrier between two stationary, parallel, and planar containment surfaces is described. A rotatable ring, attached to the first surface, has ring wedges resembling the saw-tooth array of a hole saw. Matching seal wedges are slidably attached to the ring wedges and have their motion restricted to be perpendicular to the second surface. Each seal wedge has a face parallel to the second surface. An annular elastomer seal has a central annular region attached to the seal wedges' parallel faces and has its inner and outer circumferences attached to the first surface. A rotation of the ring extends the elastomer seal's central region perpendicularly towards the second surface to create the fluid tight barrier. A counter rotation removes the barrier. 6 figs.

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

    PubMed

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

    2009-01-01

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

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

    PubMed

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

    2009-01-01

    We report on a 58-year-old male who presented with an enlarging cervical hematoma 3 months following carotid endarterectomy with Dacron patch repair, due to septic disruption of the Dacron patch secondary to presumed infection. The essential features of this case are the control of the proximal common carotid artery gained through a median sternotomy, because the patient was markedly obese with minimal thyromental distance, and the treatment consisting of in situ polytetrafluoroethylene bypass grafting, due to the absence of a suitable autogenous saphenous vein. Median sternotomy is rarely required in case of reintervention for septic false aneurysms and hematomas following carotid endarterectomy but should be considered whenever difficult control of the common carotid artery, when entering the previous cervicotomy, is anticipated. In situ polytetrafluoroethylene grafting can be considered if autogenous vein material is lacking. PMID:19875014

  15. The Artful Universe Expanded

    NASA Astrophysics Data System (ADS)

    Barrow, John D.

    2005-07-01

    Our love of art, writes John Barrow, is the end product of millions of years of evolution. How we react to a beautiful painting or symphony draws upon instincts laid down long before humans existed. Now, in this enhanced edition of the highly popular The Artful Universe , Barrow further explores the close ties between our aesthetic appreciation and the basic nature of the Universe. Barrow argues that the laws of the Universe have imprinted themselves upon our thoughts and actions in subtle and unexpected ways. Why do we like certain types of art or music? What games and puzzles do we find challenging? Why do so many myths and legends have common elements? In this eclectic and entertaining survey, Barrow answers these questions and more as he explains how the landscape of the Universe has influenced the development of philosophy and mythology, and how millions of years of evolutionary history have fashioned our attraction to certain patterns of sound and color. Barrow casts the story of human creativity and thought in a fascinating light, considering such diverse topics as our instinct for language, the origins and uses of color in nature, why we divide time into intervals as we do, the sources of our appreciation of landscape painting, and whether computer-generated fractal art is really art. Drawing on a wide variety of examples, from the theological questions raised by St. Augustine and C.S. Lewis to the relationship between the pure math of Pythagoras and the music of the Beatles, The Artful Universe Expanded covers new ground and enters a wide-ranging debate about the meaning and significance of the links between art and science.

  16. Advanced expander test bed program

    NASA Technical Reports Server (NTRS)

    Masters, A. I.; Mitchell, J. C.

    1991-01-01

    The Advanced Expander Test Bed (AETB) is a key element in NASA's Chemical Transfer Propulsion Program for development and demonstration of expander cycle oxygen/hydrogen engine technology component technology for the next space engine. The AETB will be used to validate the high-pressure expander cycle concept, investigate system interactions, and conduct investigations of advanced missions focused components and new health monitoring techniques. The split-expander cycle AETB will operate at combustion chamber pressures up to 1200 psia with propellant flow rates equivalent to 20,000 lbf vacuum thrust.

  17. Advanced expander test bed engine

    NASA Technical Reports Server (NTRS)

    Mitchell, J. P.

    1992-01-01

    The Advanced Expander Test Bed (AETB) is a key element in NASA's Space Chemical Engine Technology Program for development and demonstration of expander cycle oxygen/hydrogen engine and advanced component technologies applicable to space engines as well as launch vehicle upper stage engines. The AETB will be used to validate the high pressure expander cycle concept, study system interactions, and conduct studies of advanced mission focused components and new health monitoring techniques in an engine system environment. The split expander cycle AETB will operate at combustion chamber pressures up to 1200 psia with propellant flow rates equivalent to 20,000 lbf vacuum thrust.

  18. Liquid-crystal alignment on polytetrafluoroethylene and high-density polyethylene thin films studied by optical second-harmonic generation

    NASA Astrophysics Data System (ADS)

    Dennis, John R.; Vogel, Viola

    1998-05-01

    We have used optical second-harmonic generation to study surface molecular order in a liquid-crystal (4'-n-octyl-4-cyano-biphenyl, or 8CB) on shear-deposited polymer films. The films are highly oriented layers of polytetrafluoroethylene (PTFE) or high-density polyethylene (HDPE), with a surface topology of uniaxially aligned nanoscale ridges and grooves, which are used as versatile substrates for oriented growth and alignment of other materials. In nematic 8CB cells made with either polymer, the surface monolayers of 8CB were aligned along the polymer orientation axis, and showed C2ν symmetry. In the isotropic phase, the surface monolayer alignment in these cells was lost. Monolayers of 8CB evaporated onto either polymer showed little or no alignment. These data indicate that the PTFE and HDPE films do not produce the strong epitaxylike alignment seen on some cloth-rubbed polymer surfaces. Instead, alignment appears to be primarily caused by surface ridges through an elastic, bulk-mediated mechanism.

  19. Elevated cholinesterase activity and increased urinary excretion of inorganic fluorides in the workers producing fluorine-containing plastic (polytetrafluoroethylene)

    SciTech Connect

    Baohui Xu |; Jiusun Zhang; Guaogeng Mao; Guifen Yang; Aini Chen; Aoyama, Kohji; Matsushita, Toshio; Ueda, Atsushi

    1992-07-01

    Fluoropolymers are widely used in thermal and electrical industries. Polytetrafluoroethylene (PTFE) plastic is a typical one. During its production, workers are occupationally exposed to many organic fluorides, especially tetrafluoroethylene, chlorodifluoromethane, PTFE and its thermal decomposition products. Of these compounds, it has been documented that following inhalation of combustion products of PTFE the focal hemorrhages, edema, fibrin deposition in lungs and renal infarcts were observed in rats. Odum and Green have demonstrated a marked damage to proximal tubule of kidney with no effects on the liver in rats exposed to 6000 ppm tetrafluoroethylene for 6 hr. The investigations of the hazards of these compounds to workers have been mainly focused on acute toxicity. There have been some reports that polymers and its pyrolysis caused polymer fume fever and pulmonary edema. In practice, workers engaged in PTFE manufacture are chronically exposed to the above-mentioned chemicals, but little was known about the hazards ascribed to these chemicals. To clarify the influences of the exposed chemicals on health in PTFE production we conducted a mass survey investigation in a PTFE production factory. As a result, in addition to the nephrotoxicity characterized by elevated ALP and NAG activities in urine, more interestingly, we have also found a reversible increase in cholinesterase (ChE) activity and enhanced urinary excretion of inorganic fluorides in workers engaged in PTFE production. We report here these findings and discuss their physiological significance. 18 refs., 4 tabs.

  20. Simultaneous and long-lasting hydrophilization of inner and outer wall surfaces of polytetrafluoroethylene tubes by transferring atmospheric pressure plasmas

    NASA Astrophysics Data System (ADS)

    Chen, Faze; Song, Jinlong; Huang, Shuai; Xu, Sihao; Xia, Guangqing; Yang, Dezheng; Xu, Wenji; Sun, Jing; Liu, Xin

    2016-09-01

    Plasma hydrophilization is a general method to increase the surface free energy of materials. However, only a few works about plasma modification focus on the hydrophilization of tube inner and outer walls. In this paper, we realize simultaneous and long-lasting plasma hydrophilization on the inner and outer walls of polytetrafluoroethylene (PTFE) tubes by atmospheric pressure plasmas (APPs). Specifically, an Ar atmospheric pressure plasma jet (APPJ) is used to modify the PTFE tube’s outer wall and meanwhile to induce transferred He APP inside the PTFE tube to modify its inner wall surface. The optical emission spectrum (OES) shows that the plasmas contain many chemically active species, which are known as enablers for various applications. Water contact angle (WCA) measurements, x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) are used to characterize the plasma hydrophilization. Results demonstrate that the wettability of the tube walls are well improved due to the replacement of the surface fluorine by oxygen and the change of surface roughness. The obtained hydrophilicity decreases slowly during more than 180 d aging, indicating a long-lasting hydrophilization. The results presented here clearly demonstrate the great potential of transferring APPs for surface modification of the tube’s inner and outer walls simultaneously.

  1. Radiolytic preparation and characterization of hydrophilic poly(acrylonitrile-co-vinylsulfonate)-grafted porous poly(tetrafluoroethylene) substrates

    NASA Astrophysics Data System (ADS)

    Park, Byeong-Hee; Sohn, Joon-Yong; Shin, Junhwa

    2016-01-01

    In this study, a hydrophilic copolymer of acrylonitrile (AN) and sodium vinylsulfonate (SVS) was grafted into a highly hydrophobic porous poly(tetrafluoroethylene) (PTFE) substrate using a gamma-ray irradiation method and the grafted substrate was used as a substrate for impregnating a hydrophilic ionomer, Nafion. The results of FT-IR and TGA analysis of the prepared substrate showed that the SVS/AN monomers were successfully grafted into the porous PTFE film. The results of degree of grafting, elemental analyzer, and contact angle analysis showed that the hydrophilicity of the prepared PTFE-g-P(AN-co-VS) substrate was increased with an increase in the amount of SVS/AN graft copolymers. Also, the results of FE-SEM and Gurley number measurement showed that the pores in the substrate were reduced as the amount of SVS/AN copolymers grafted into the substrate increased. The prepared porous PTFE-g-P(AN-co-VS) substrate at an irradiation dose of 70 kGy was found to impregnate Nafion ionomer effectively compared to the original porous PTFE substrate. These results suggest that the prepared PTFE-g-P(AN-co-VS) substrate can be effectively used for the impregnation of polymer electrolyte (Nafion) to prepare a reinforced composite membrane.

  2. Core-Shell Al-Polytetrafluoroethylene (PTFE) Configurations to Enhance Reaction Kinetics and Energy Performance for Nanoenergetic Materials.

    PubMed

    Wang, Jun; Qiao, Zhiqiang; Yang, Yuntao; Shen, Jinpeng; Long, Zhang; Li, Zhaoqian; Cui, Xudong; Yang, Guangcheng

    2016-01-01

    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). PMID:26612396

  3. Enhanced performance of gas diffusion electrode for electrochemical reduction of carbon dioxide to formate by adding polytetrafluoroethylene into catalyst layer

    NASA Astrophysics Data System (ADS)

    Wang, Qinian; Dong, Heng; Yu, Han; Yu, Hongbing

    2015-04-01

    Gas diffusion electrode (GDE) with Nafion bonded catalyst layer (CL) for electrochemical reduction of CO2 to formate (ERCF) suffers from CO2 mass transfer limitation. In this work, polytetrafluoroethylene (PTFE) with contents of 5.9 wt%, 7.7 wt%, 11.1 wt% and 20 wt% are added into the CL of the GDE with Sn catalyst (P-SGDE) for ERCF. The morphologies and porous structures of the P-SGDEs are examined by scanning electron microscope and mercury intrusion measurement, respectively. The electrochemical performances of the P-SGDEs are investigated by linear sweep voltammetry, electrochemical impedance spectroscopy and constant potential electrolysis. The results show that the Faraday efficiency (86.75 ± 2.89%) and current density (21.67 ± 1.29 mA cm-2) for ERCF were improved by 25.4% and 25.8% respectively when the content of PTFE is 11.1 wt%, probably owing to the enhancement in the catalyst active surface area and CO2 diffusion. This Faraday efficiency is the highest one found for ERCF with Sn GDE under similar conductions.

  4. High-performance LiFePO4/C electrode with polytetrafluoroethylene as an aqueous-based binder

    NASA Astrophysics Data System (ADS)

    Gao, Shiyan; Su, Yuefeng; Bao, Liying; Li, Ning; Chen, Lai; Zheng, Yu; Tian, Jun; Li, Jian; Chen, Shi; Wu, Feng

    2015-12-01

    An environmental-friendly and low-cost polymer, polytetrafluoroethylene (PTFE) has been applied as an aqueous-based binder for the fabrication of LiFePO4/C electrode. The electrode with PTFE has been compared to the electrode with the conventional binder, polyvinylidene fluoride (PVDF) via Rheology test, X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and electrochemical tests. The Rheology test indicates that the viscosity of the slurry prepared with PTFE as a binder is better than that prepared with PVDF. The electrochemical measurements demonstrate that the electrode with PTFE binder displays a higher discharge capacity of 161.1 mAh g-1 compared to the electrode with PVDF binder, which shows a discharge capacity of 150.7 mAh g-1. The EIS analysis indicates the LiFePO4/C electrode with PTFE binder shows a higher ionic conductivity and a smaller increasing in charge transfer rate compared to the LiFePO4/C electrode with PVDF binder. In addition, the electrodes applying the aqueous-based binder have been optimized by controlling the moisture content in the electrodes. The electrochemical enhancement of these electrodes can be achieved by controlling the vacuum drying temperature and time during the preparation of the electrodes.

  5. Thermodynamic properties and transport coefficients of air thermal plasmas mixed with ablated vapors of Cu and polytetrafluoroethylene

    NASA Astrophysics Data System (ADS)

    Zhang, JunMin; Lu, ChunRong; Guan, YongGang; Liu, WeiDong

    2015-10-01

    Because the fault arc in aircraft electrical system often causes a fire, it is particularly important to analyze its energy and transfer for aircraft safety. The calculation of arc energy requires the basic parameters of the arc. This paper is mainly devoted to the calculations of equilibrium composition, thermodynamic properties (density, molar weight, enthalpy, and specific heat at constant pressure) and transport coefficients (thermal conductivity, electrical conductivity, and viscosity) of plasmas produced by a mixture of air, Cu, and polytetrafluoroethylene under the condition of local thermodynamic equilibrium. The equilibrium composition is determined by solving a system of equations around the number densities of each species. The thermodynamic properties are obtained according to the standard thermodynamic relationships. The transport coefficients are calculated using the Chapman-Enskog approximations. Results are presented in the temperature range from 3000 to 30 000 K for pressures of 0.08 and 0.1 MPa, respectively. The results are more accurate and are reliable reference data for theoretical analysis and computational simulation of the behavior of fault arc.

  6. A polytetrafluoroethylene porous membrane and dimethylhexadecylamine quaternized poly (vinyl benzyl chloride) composite membrane for intermediate temperature fuel cells

    NASA Astrophysics Data System (ADS)

    Cao, Yuan-Cheng; Xu, Chenxi; Zou, Linling; Scott, Keith; Liu, Jiyan

    2015-10-01

    A composite material for phosphoric acid (PA) loaded membrane was prepared using a porous polytetrafluoroethylene (PTFE) thin film. N, N-Dimethylhexadecylamine partially quaternized poly (vinyl benzyl chloride) (qPVBzCl-) was synthesized as the substrate for the phosphoric acid loaded polymer membrane. SEM observation indicated that the pores were filled with the qPVBzCl-. The maximum PA loading level was calculated to be 4.67-5.12 per repeat unit on average. TGA results showed that resultant composite membrane was stable in the intermediate temperature from 100 °C to 200 °C. The composite membrane tensile stress was 56.23 MPa, and the Young's Modulus was 0.25 GPa, and the fractured elongation was 23%. The conductivity of the composite membrane after the PA addition (H3PO4@PTFE/qPVBzCl-) increased from 0.085 S cm-1 to 0.11 S cm-1 from 105 °C to 180 °C. The peak power density of the H2/O2 at 175 °C under low humidity condition (<1%) for H3PO4@PTFE/qPVBzCl- membranes was 360 mW cm-2.

  7. Particle size effect on strength, failure, and shock behavior in polytetrafluoroethylene-Al-W granular composite materials

    NASA Astrophysics Data System (ADS)

    Herbold, E. B.; Nesterenko, V. F.; Benson, D. J.; Cai, J.; Vecchio, K. S.; Jiang, F.; Addiss, J. W.; Walley, S. M.; Proud, W. G.

    2008-11-01

    The variation of metallic particle size and sample porosity significantly alters the dynamic mechanical properties of high density granular composite materials processed using a cold isostatically pressed mixture of polytetrafluoroethylene (PTFE), aluminum (Al), and tungsten (W) powders. Quasistatic and dynamic experiments are performed with identical constituent mass fractions with variations in the size of the W particles and pressing conditions. The relatively weak polymer matrix allows the strength and fracture modes of this material to be governed by the granular type behavior of agglomerated metal particles. A higher ultimate compressive strength was observed in relatively high porosity samples with small W particles compared to those with coarse W particles in all experiments. Mesoscale granular force chains of the metallic particles explain this unusual phenomenon as observed in hydrocode simulations of a drop-weight test. Macrocracks forming below the critical failure strain for the matrix and unusual behavior due to a competition between densification and fracture in dynamic tests of porous samples were also observed. Numerical modeling of shock loading of this granular composite material demonstrated that the internal energy, specifically thermal energy, of the soft PTFE matrix can be tailored by the W particle size distribution.

  8. Hydrophobic properties of polytetrafluoroethylene thin films fabricated at various catalyzer temperatures through catalytic chemical vapor deposition using a tungsten catalyzer.

    PubMed

    Cha, Jeong Ok; Yeo, Seung Jun; Pode, Ramchandra; Ahn, Jeung Sun

    2011-07-01

    Using the catalytic chemical vapor deposition (Cat-CVD) method, polytetrafluoroethylene (PTFE) thin films were fabricated on Si(100) substrates at various catalyzer temperatures, using a tungsten catalyzer, and Fourier transform infrared (FTIR) spectroscopy and X-ray photoemission spectroscopy (XPS) were used to confirm the fabrication of the films. An atomic-force microscope (AFM) and a scanning electron microscope (SEM) were employed to study the correlation between the wettability and surface morphology of the samples. It was found that the wettability of the PTFE thin films fabricated via Cat-CVD is strongly correlated with the sizes of the film surfaces' nanoprotrusions, and that superhydrophobic PTFE thin-film surfaces can be easily achieved by controlling the sizes of the nanoprotrusions through the catalyzer temperature. The comparison of the wettability values and surface morphologies of the films confirmed that nanoscale surface roughness enhances the hydrophobic properties of PTFE thin films. Further, the detailed analysis of the films' surface morphologies from their AFM images with the use of the Wenzel and Cassie models confirmed that the nanoscale surface roughness enhanced the hydrophobic property of the PTFE films. Further, the variations of the wettability of the PTFE thin films prepared via Cat-CVD are well explained by the Cassie model. It seems that the increase in the trapping air and the reduction of the liquid-solid contact area are responsible for the superhydrophobicity of the PTFE thin films prepared via Cat-CVD. PMID:22121615

  9. POLYTETRAFLUOROETHYLENE-RICH POLYPHENLENESULFIDE BLEND TOP COATINGS FOR MITIGATING CORROSION OF CARBON STEEL IN 300 DEGREE CELCIUS BRINE.

    SciTech Connect

    SUGAMA, T.; JUNG, D.

    2006-06-01

    We evaluated usefulness of a coating system consisting of an underlying polyphenylenesulfide (PPS) layer and top polytetrafluoroethylene (PTFE)-blended PPS layer as low friction, water repellent, anti-corrosion barrier film for carbon steel steam separators in geothermal power plants. The experiments were designed to obtain information on kinetic coefficient of friction, surface free energy, hydrothermal oxidation, alteration of molecular structure, thermal stability, and corrosion protection of the coating after immersing the coated carbon steel coupons for up to 35 days in CO{sub 2}-laden brine at 300 C. The superficial layer of the assembled coating was occupied by PTFE self-segregated from PPS during the melt-flowing process of this blend polymer; it conferred an outstanding slipperiness and water repellent properties because of its low friction and surface free energy. However, PTFE underwent hydrothermal oxidation in hot brine, transforming its molecular structure into an alkylated polyfluorocarboxylate salt complex linked to Na. Although such molecular transformation increased the friction and surface free energy, and also impaired the thermal stability of PTFE, the top PTFE-rich PPS layer significantly contributed to preventing the permeation of moisture and corrosive electrolytes through the coating film, so mitigating the corrosion of carbon steel.

  10. Thermodynamic properties and transport coefficients of air thermal plasmas mixed with ablated vapors of Cu and polytetrafluoroethylene

    SciTech Connect

    Zhang, JunMin E-mail: guanyg@tsinghua.edu.cn; Lu, ChunRong; Guan, YongGang E-mail: guanyg@tsinghua.edu.cn; Liu, WeiDong

    2015-10-15

    Because the fault arc in aircraft electrical system often causes a fire, it is particularly important to analyze its energy and transfer for aircraft safety. The calculation of arc energy requires the basic parameters of the arc. This paper is mainly devoted to the calculations of equilibrium composition, thermodynamic properties (density, molar weight, enthalpy, and specific heat at constant pressure) and transport coefficients (thermal conductivity, electrical conductivity, and viscosity) of plasmas produced by a mixture of air, Cu, and polytetrafluoroethylene under the condition of local thermodynamic equilibrium. The equilibrium composition is determined by solving a system of equations around the number densities of each species. The thermodynamic properties are obtained according to the standard thermodynamic relationships. The transport coefficients are calculated using the Chapman-Enskog approximations. Results are presented in the temperature range from 3000 to 30 000 K for pressures of 0.08 and 0.1 MPa, respectively. The results are more accurate and are reliable reference data for theoretical analysis and computational simulation of the behavior of fault arc.

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  12. Monolithical aspherical beam expanding systems

    NASA Astrophysics Data System (ADS)

    Fuchs, U.; Matthias, Sabrina

    2014-10-01

    Beam expanding is a common task, where Galileo telescopes are preferred. However researches and customers have found limitations when using these systems. A new monolithical solution which is based on the usage of only one aspherical component will be presented. It will be shown how to combine up to five monolithical beam expanding systems and to keep the beam quality at diffraction limitation. Insights will be given how aspherical beam expanding systems will help using larger incoming beams and reducing the overall length of such a system. Additionally an add-on element for divergence and wavelength adaption will be presented.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  14. Advanced expander test bed program

    NASA Technical Reports Server (NTRS)

    Riccardi, D. P.; Mitchell, J. C.

    1993-01-01

    The Advanced Expander Test Bed (AETB) is a key element in NASA's Space Chemical Engine Technology Program for development and demonstration of expander cycle oxygen/hydrogen engine and advanced component technologies applicable to space engines as well as launch vehicle upper stage engines. The AETB will be used to validate the high-pressure expander cycle concept, investigate system interactions, and conduct investigations of advanced mission focused components and new health monitoring techniques in an engine system environment. The split expander cycle AETB will operate at combustion chamber pressures up to 1200 psia with propellant flow rates equivalent to 20,000 lbf vacuum thrust. Contract work began 27 Apr. 1990. During 1992, a major milestone was achieved with the review of the final design of the oxidizer turbopump in Sep. 1992.

  15. Study of methods for applying and enhancing transfer film coatings of polytetrafluoroethylene (PTEE) to Space Shuttle Main Engine (SSME) High Pressure Oxygen Turbo Pump (HPOTP) bearings

    NASA Technical Reports Server (NTRS)

    Kannel, J. W.; Dufrane, K. F.; Zugaro, F. F.

    1981-01-01

    Machines were constructed and evaluated for burnishing polytetrafluoroethylene on balls for use in the high pressure oxygen turbopump (HPOTP). The most positive performance was obtained with single-ball burnishing, but one technique for burnishing three balls simultaneously holds promise. Evaluations of the coatings in a HPOTP bearing of earlier design (employed smaller diameter balls) showed very little life enhancement before high torque and ball and race wear initiated. Other coating techniques, such as molybdenum disulfide combined with PTFE transfer films, hold promise for providing the more durable quantities of solid lubricant needed for the bearings.

  16. Federal government expands compliance initiatives.

    PubMed

    Dugan, J K

    1997-09-01

    In 1995, the Federal government initiated Operation Restore Trust to increase enforcement of fraud and abuse regulations in Medicare and Medicaid programs. With the success of the original initiative, the government is expanding the project to additional states and program areas. The initial scrutiny of home health agencies, nursing homes, hospice care, and durable medical equipment is being expanded to managed care plans and acute care hospitals with an eye toward DRG creep. To manage this increased enforcement activity, healthcare organizations should institute comprehensive corporate compliance programs. Such programs should provide a framework that delineates responsibilities and provides a systematic means to resolve issues in a timely manner. PMID:10170318

  17. Federal government expands compliance initiatives.

    PubMed

    Dugan, J K

    1997-09-01

    In 1995, the Federal government initiated Operation Restore Trust to increase enforcement of fraud and abuse regulations in Medicare and Medicaid programs. With the success of the original initiative, the government is expanding the project to additional states and program areas. The initial scrutiny of home health agencies, nursing homes, hospice care, and durable medical equipment is being expanded to managed care plans and acute care hospitals with an eye toward DRG creep. To manage this increased enforcement activity, healthcare organizations should institute comprehensive corporate compliance programs. Such programs should provide a framework that delineates responsibilities and provides a systematic means to resolve issues in a timely manner.

  18. Thermal stability of micro-nano structures and superhydrophobicity of polytetrafluoroethylene films formed by hot embossing via a picosecond laser ablated template

    NASA Astrophysics Data System (ADS)

    Gong, Dingwei; Long, Jiangyou; Fan, Peixun; Jiang, Dafa; Zhang, Hongjun; Zhong, Minlin

    2015-03-01

    We report here a simple and efficient hot embossing process capable of mass fabricating superhydrophobic and self-cleaning polytetrafluoroethylene (PTFE) film surfaces. Adding superhydrophobicity to hydrophobic polytetrafluoroethylene (PTFE) significantly enhances their application potential in industry as well as in daily life. We applied a picosecond laser to fabricate regular array of micro-holes companied with submicron structures on high strength steel substrate to form a lotus-leaf-like template. Then the hot embossing process was performed on flat PTFE films to introduce a dual-scale structure composed of the micro-scale protrusions and nano-scale fibril structures on the top of protrusions. The hot embossing parameters such as the embossing pressure and time were optimized to achieve required micro- and nano-scale dual structure on PTFE film very closed to the similar dual structure of the lotus leaf surface. The PTFE films then exhibited superhydrophobicity with contact angle up to 154.6° and sliding angle of as low as 5.5°. The thermal stability of the superhydrophobic PTFE films was investigated from room temperature up to 430 °C. We demonstrate that the micro-nano dual structure on PTFE films and their superhydrophobicity is thermally stable up to 340 °C. The micro-scale protrusions will collapse and the superhydrophobicity will lose when the temperate is over 370 °C.

  19. The Expanding Frontier of Pluralism.

    ERIC Educational Resources Information Center

    King, Edmund

    1983-01-01

    Looks at the expanding frontier of pluralism in terms of reappraising the relationship of formal education to the advent of the constant change (occupational and social) accelerated by the microprocessor revolution and readjusting provisions in educational systems to meet the different needs of different populations. (AH)

  20. Expanding the Concept of Literacy.

    ERIC Educational Resources Information Center

    Daley, Elizabeth

    2003-01-01

    Explores four arguments for an expanded definition of literacy to include the multimedia language of the screen. Describes efforts to develop this literacy in students at the Institute for Multimedia Literacy at the Annenberg Center of the University of Southern California. (EV)

  1. Expanding the eukaryotic genetic code

    DOEpatents

    Chin, Jason W.; Cropp, T. Ashton; Anderson, J. Christopher; Schultz, Peter G.

    2010-09-14

    This invention provides compositions and methods for producing translational components that expand the number of genetically encoded amino acids in eukaryotic cells. The components include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, orthogonal pairs of tRNAs/synthetases and unnatural amino acids. Proteins and methods of producing proteins with unnatural amino acids in eukaryotic cells are also provided.

  2. Expanding the eukaryotic genetic code

    DOEpatents

    Chin, Jason W.; Cropp, T. Ashton; Anderson, J. Christopher; Schultz, Peter G.

    2009-10-27

    This invention provides compositions and methods for producing translational components that expand the number of genetically encoded amino acids in eukaryotic cells. The components include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, orthogonal pairs of tRNAs/synthetases and unnatural amino acids. Proteins and methods of producing proteins with unnatural amino acids in eukaryotic cells are also provided.

  3. Expanding the eukaryotic genetic code

    SciTech Connect

    Chin, Jason W.; Cropp, T. Ashton; Anderson, J. Christopher; Schultz, Peter G.

    2009-11-17

    This invention provides compositions and methods for producing translational components that expand the number of genetically encoded amino acids in eukaryotic cells. The components include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, orthogonal pairs of tRNAs/synthetases and unnatural amino acids. Proteins and methods of producing proteins with unnatural amino acids in eukaryotic cells are also provided.

  4. Expanding the eukaryotic genetic code

    SciTech Connect

    Chin, Jason W; Cropp, T. Ashton; Anderson, J. Christopher; Schultz, Peter G

    2015-02-03

    This invention provides compositions and methods for producing translational components that expand the number of genetically encoded amino acids in eukaryotic cells. The components include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, orthogonal pairs of tRNAs/synthetases and unnatural amino acids. Proteins and methods of producing proteins with unnatural amino acids in eukaryotic cells are also provided.

  5. Expanding the eukaryotic genetic code

    DOEpatents

    Chin, Jason W.; Cropp, T. Ashton; Anderson, J. Christopher; Schultz, Peter G.

    2012-02-14

    This invention provides compositions and methods for producing translational components that expand the number of genetically encoded amino acids in eukaryotic cells. The components include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, orthogonal pairs of tRNAs/synthetases and unnatural amino acids. Proteins and methods of producing proteins with unnatural amino acids in eukaryotic cells are also provided.

  6. Expanding the eukaryotic genetic code

    SciTech Connect

    Chin, Jason W.; Cropp, T. Ashton; Anderson, J. Christopher; Schultz, Peter G.

    2009-12-01

    This invention provides compositions and methods for producing translational components that expand the number of genetically encoded amino acids in eukaryotic cells. The components include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, orthogonal pairs of tRNAs/synthetases and unnatural amino acids. Proteins and methods of producing proteins with unnatural amino acids in eukaryotic cells are also provided.

  7. Expanding the eukaryotic genetic code

    SciTech Connect

    Chin, Jason W.; Cropp, T. Ashton; Anderson, J. Christopher; Schultz, Peter G.

    2013-01-22

    This invention provides compositions and methods for producing translational components that expand the number of genetically encoded amino acids in eukaryotic cells. The components include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, orthogonal pairs of tRNAs/synthetases and unnatural amino acids. Proteins and methods of producing proteins with unnatural amino acids in eukaryotic cells are also provided.

  8. Expanding the eukaryotic genetic code

    DOEpatents

    Chin, Jason W.; Cropp, T. Ashton; Anderson, J. Christopher; Schultz, Peter G.

    2012-05-08

    This invention provides compositions and methods for producing translational components that expand the number of genetically encoded amino acids in eukaryotic cells. The components include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, orthogonal pairs of tRNAs/synthetases and unnatural amino acids. Proteins and methods of producing proteins with unnatural amino acids in eukaryotic cells are also provided.

  9. Expanding the Universe of Education.

    ERIC Educational Resources Information Center

    Parsons, Elizabeth

    1996-01-01

    Definitions of "education" and "rural" are debunked and expanded. The three major tasks of rural education are educating people to understand their own needs, the unavoidable changes that will transform rural Australia within their lifetimes, and the range of technologies that can enhance their well-being. Presents a strategy for educating…

  10. Common Ground: Expanding Our Horizons.

    ERIC Educational Resources Information Center

    McDevitt, Michele J.

    In "Common Ground: Dialogue, Understanding, and the Teaching of Composition," Kurt Spellmeyer seeks to familiarize students and teachers with the linguistic and cultural no-man's-land separating them. Reinstating the value of two writing conventions often used by traditional students--expressive and commonplaces--can help expand on the horizons of…

  11. Teleteach Expanded Delivery System: Evaluation.

    ERIC Educational Resources Information Center

    Christopher, G. Ronald; Milam, Alvin L.

    In order to meet the demand for Air Force Institute of Technology (AFIT) professional continuing education (PCE) courses within the School of Systems and Logistics and the School of Engineering, the Teleteach Expanded Delivery System (TEDS) for instruction of Air Force personnel at remote locations was developed and evaluated. TEDS uses a device…

  12. Helical screw expander evaluation project

    NASA Technical Reports Server (NTRS)

    Mckay, R.

    1982-01-01

    A one MW helical rotary screw expander power system for electric power generation from geothermal brine was evaluated. The technology explored in the testing is simple, potentially very efficient, and ideally suited to wellhead installations in moderate to high enthalpy, liquid dominated field. A functional one MW geothermal electric power plant that featured a helical screw expander was produced and then tested with a demonstrated average performance of approximately 45% machine efficiency over a wide range of test conditions in noncondensing, operation on two-phase geothermal fluids. The Project also produced a computer equipped data system, an instrumentation and control van, and a 1000 kW variable load bank, all integrated into a test array designed for operation at a variety of remote test sites. Data are presented for the Utah testing and for the noncondensing phases of the testing in Mexico. Test time logged was 437 hours during the Utah tests and 1101 hours during the Mexico tests.

  13. Seal-less cryogenic expander

    SciTech Connect

    Faria, L.E.; Christopher, E.H.

    1987-12-08

    In an expander for use in a split Stirling cycle refrigeration system of the type wherein a displacer moves with reciprocating motion inside an expander housing, and wherein a plunger force and a regenerator force are formed on the displacer, the plunger force cyclically varying and having a time of minimum and maximum plunger force amplitude, and the regenerator force cyclically varying and having a time of minimum and maximum regenerator force amplitude, the improvement is described comprising: (a) means for maintaining displacer forces, such that the maximum plunger force amplitude is substantially equal to the maximum regenerator force amplitude; and (b) means for adjusting a time difference, the time difference being the time between the time of maximum plunger force and the time of maximum regenerator force such that a measure of the cooling power of the refrigeration system is maximized.

  14. Magical NiTi expander

    PubMed Central

    Katti, Chandrika Girish; Katti, Girish; Kallur, Ravi; Ghali, Srinivas Rao

    2013-01-01

    A 24-year-old male patient was referred to our department for expansion of the constricted maxillary arch as a presurgical procedure for the correction of congenital facial disfigurement. On examination, the patient had a convex profile, increased interlabial gap, tongue thrust, limited mouth opening, posterior crossbite, asymmetric ‘V’-shaped maxillary arch with severe constriction, crowding of anterior teeth in the maxillary arch and a massive open bite. Radiographic investigations included orthopantomograph and occlusal radiographs. The patient photographs and models were analysed. On careful evaluation, the treatment for maxillary arch expansion was planned with a nickel titanium (NiTi) slow maxillary expander along with fixed mechanotherapy for alignment of teeth. An unexpectedly successful outcome was appreciated from the treatment. An emphasis should be laid on selecting and treating the case of constricted arches with a surgical or non-surgical approach, as expansion can be achieved orthodontically by using NiTi expanders. PMID:23867876

  15. Entropy in an expanding universe.

    PubMed

    Frautschi, S

    1982-08-13

    The question of how the observed evolution of organized structures from initial chaos in the expanding universe can be reconciled with the laws of statistical mechanics is studied, with emphasis on effects of the expansion and gravity. Some major sources of entropy increase are listed. An expanding "causal" region is defined in which the entropy, though increasing, tends to fall further and further behind its maximum possible value, thus allowing for the development of order. The related questions of whether entropy will continue increasing without limit in the future, and whether such increase in the form of Hawking radiation or radiation from positronium might enable life to maintain itself permanently, are considered. Attempts to find a scheme for preserving life based on solid structures fail because events such as quantum tunneling recurrently disorganize matter on a very long but fixed time scale, whereas all energy sources slow down progressively in an expanding universe. However, there remains hope that other modes of life capable of maintaining themselves permanently can be found.

  16. Subtask 1.15-Passive Diffusion Sample Bags Made from Expanded Polytetrafluorethylene (ePTFE) to Measure VOC Concentrations in Groundwater

    SciTech Connect

    Barry W. Botnen

    2006-08-01

    With laboratory testing of expanded polytetrafluoroethylene (ePTFE) membranes complete, collected data support that volatile organic compound (VOC) molecules will readily diffuse across ePTFE membranes. Membrane samples, supplied by BHA Technologies (GE Osmonics), were tested to determine diffusion rates for VOCs in groundwater. Tests were conducted using membranes with two different pore sizes, with and without thermally laminated spun bond backing, and multiple concentrations of contaminated groundwater. Results suggest that typical residence times associated with traditional samplers constructed of polyethylene (2 weeks) can be reduced by 1 week using ePTFE membranes (reducing project costs) and that VOCs will diffuse more readily at lower temperatures (2.2-3.3 C) across ePTFE materials.

  17. Infrared, spectral, directional-hemispherical reflectance of fused silica, Teflon polytetrafluoroethylene polymer, chrome oxide ceramic particle surface, Pyromark 2500 paint, Krylon 1602 paint, and Duraflect coating

    NASA Astrophysics Data System (ADS)

    Persky, Merle J.; Szczesniak, Martin

    2008-04-01

    Infrared, spectral, directional-hemispherical reflectivity measurements of polished fused silica, Teflon polytetrafluoroethylene polymer, chrome oxide ceramic particle surface, Pyromark 2500 paint, Krylon 1602 paint, and Duraflect coating are provided. The reflectance was measured with an estimated accuracy of 0.01 to 0.02 units and a precision of 0.005 units. All the surfaces were measured at ambient temperatures. Additionally, the chrome oxide ceramic particle surface was measured at 486 K and the Pyromark 2500 at four temperatures to 877 K. Polarization measurements are also provided for fused silica, Duraflect, chrome oxide ceramic particle surface, and Pyromark 2500 paint. Separate diffuse and specular reflectance components for the Duraflect and chrome oxide ceramic surfaces are included. Fresnel-based predictions for fused silica parallel and perpendicular polarized reflections are compared to measurements. It is notable that the Pyromark 2500 and chrome oxide ceramic particle surfaces exhibit a significant lack of manufacturing repeatability.

  18. Study on the anti-wear performance of Ni-base composite coating sucker joint that contains nano-diamond and nano-polytetrafluoroethylene.

    PubMed

    Wang, Wei-Zhang; Yan, Xiang-Zhen; Wang, Hai-Wen; Wang, Ming-Bo

    2009-02-01

    With the development of oilfields, the problem of eccentric wear between casing and sucker rod in rod-pumped wells operation is more and more severe. Investigations on the eccentric wear show that the abrasion of sucker rod joint is more serious than the sucker rod itself. A new method of producing the Ni-base composite coating that contains nano-diamond and nano-polytetrafluoroethylene (PTFE) on sucker joint obtained by electrodeposition is presented in this paper. The test results show that the anti-wear performance and hardness of the sucker rod improve significantly with the increase of nano-diamond. The addition of nano-PTFE particle is useful in reducing the friction factor. Field tests demonstrate that the life of the sucker rod joint is increased and the maintenance cycle of the rod-pumped well is prolonged. PMID:19441509

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

    NASA Astrophysics Data System (ADS)

    Jeong, Gisu; Kim, MinJoong; Han, Junyoung; Kim, Hyoung-Juhn; Shul, Yong-Gun; Cho, EunAe

    2016-08-01

    Although high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) have a high carbon monoxide tolerance and allow for efficient water management, their practical applications are limited due to their lower performance than conventional low-temperature PEMFCs. Herein, we present a high-performance membrane-electrode assembly (MEA) with an optimal polytetrafluoroethylene (PTFE) content for HT-PEMFCs. Low or excess PTFE content in the electrode leads to an inefficient electrolyte distribution or severe catalyst agglomeration, respectively, which hinder the formation of triple phase boundaries in the electrodes and result in low performance. MEAs with PTFE content of 20 wt% have an optimal pore structure for the efficient formation of electrolyte/catalyst interfaces and gas channels, which leads to high cell performance of approximately 0.5 A cm-2 at 0.6 V.

  20. Study on the anti-wear performance of Ni-base composite coating sucker joint that contains nano-diamond and nano-polytetrafluoroethylene.

    PubMed

    Wang, Wei-Zhang; Yan, Xiang-Zhen; Wang, Hai-Wen; Wang, Ming-Bo

    2009-02-01

    With the development of oilfields, the problem of eccentric wear between casing and sucker rod in rod-pumped wells operation is more and more severe. Investigations on the eccentric wear show that the abrasion of sucker rod joint is more serious than the sucker rod itself. A new method of producing the Ni-base composite coating that contains nano-diamond and nano-polytetrafluoroethylene (PTFE) on sucker joint obtained by electrodeposition is presented in this paper. The test results show that the anti-wear performance and hardness of the sucker rod improve significantly with the increase of nano-diamond. The addition of nano-PTFE particle is useful in reducing the friction factor. Field tests demonstrate that the life of the sucker rod joint is increased and the maintenance cycle of the rod-pumped well is prolonged.

  1. Shell may expand detergent alcohols

    SciTech Connect

    1996-10-23

    Shell Chemical is studying plans to expand detergent alcohols capacity in the US, CW has learned. The company is considering adding capacity for about 80 million lbs/year. If the project is approved, it would be implemented at the company`s Geismar, LA site. Shell will make a final decision on whether to proceed with the project within six months. It has been rumored to be considering a capacity addition as a result of tightening supply of natural and synthetic detergent alcohols.

  2. Unconventional microfluidics: expanding the discipline

    PubMed Central

    Nawaz, Ahmad Ahsan; Mao, Xiaole; Stratton, Zackary S.; Huang, Tony Jun

    2014-01-01

    Since its inception, the discipline of microfluidics has been harnessed for innovations in the biomedicine/chemistry fields—and to great effect. This success has had the natural side-effect of stereotyping microfluidics as a platform for medical diagnostics and miniaturized lab processes. But microfluidics has more to offer. And very recently, some researchers have successfully applied microfluidics to fields outside its traditional domains. In this Focus article, we highlight notable examples of such “unconventional” microfluidics applications (e.g., robotics, electronics). It is our hope that these early successes in unconventional microfluidics prompt further creativity, and inspire readers to expand the microfluidics discipline. PMID:23478651

  3. Unconventional microfluidics: expanding the discipline.

    PubMed

    Nawaz, Ahmad Ahsan; Mao, Xiaole; Stratton, Zackary S; Huang, Tony Jun

    2013-04-21

    Since its inception, the discipline of microfluidics has been harnessed for innovations in the biomedicine/chemistry fields-and to great effect. This success has had the natural side-effect of stereotyping microfluidics as a platform for medical diagnostics and miniaturized lab processes. But microfluidics has more to offer. And very recently, some researchers have successfully applied microfluidics to fields outside its traditional domains. In this Focus article, we highlight notable examples of such "unconventional" microfluidics applications (e.g., robotics, electronics). It is our hope that these early successes in unconventional microfluidics prompt further creativity, and inspire readers to expand the microfluidics discipline.

  4. Frost heave test being expanded

    SciTech Connect

    Not Available

    1981-03-01

    Northwest Alaskan Pipeline Co. is expanding its frost-heave testing program by adding seven test sites along the planned Alaskan gas transmission pipeline route. The test results will demonstrate the behavior of chilled pipe buried in unfrozen soils. To protect the permafrost in which the pipe will be buried, the pipeline operators will chill the gas in the line to below 32/sup 0/F. In thawed soils, however, frost heave may occur when moisture freezes on the chilled pipe, creates a frost bulb, expands the soil, and causes the chilled pipe to heave upward. Two methods being tested for preventing or minimizing frost heave are (1) insulation, and (2) replacement of frost-susceptible unfrozen soil with a selected bedding material. Each test site will consist of two 80-ft sections of 48 in-diam pipe - one bare, the other with insulation (urethane foam) or insulation plus a bedding-material replacement. The sites will have their own power-generation and refrigeration equipment, as well as data-acquisition systems that will automatically collect information from 800 sensors twice a week.

  5. Heat expanded starch-based compositions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A heat expansion process similar to that used for expanded bead polystyrene was used to expand starch-based compositions. Foam beads made by solvent extraction had the appearance of polystyrene beads but their open-cell structure precluded them from expanding further when heated. Non-porous beads, p...

  6. Drizo protects turbo expander plant

    SciTech Connect

    Frazier, C.W.; Force, J.E.

    1982-01-01

    A triethylene glycol (TEG) unit using Dow's Drizo technology in front of processes was installed in a turbo expander plant owned by Valero Hydrocarbons, San Antonio, Texas. The TEG unit was placed in the process because methanol consumption had run higher than design conditions had predicted; gas flow rates and water content varied widely; and the gas was found to be contaminated considerably with iron sulfide. The TEG unit optimized gas processing by reducing the water content of gas to the system, accepting variable gas flow and water content to smooth out feed gas quality, removing iron sulfide and other contaminants before processing, and being amenable to conversion from other equipment already in existence at other Valero plant locations. The TEG Drizo process provides an azeotropic agent injected into the hot glycol, and the glycol solution is used to reduce residual water content of gas. Details of the equipment and process conversion are given.

  7. Deep Brain Stimulation: Expanding Applications

    PubMed Central

    TEKRIWAL, Anand; BALTUCH, Gordon

    2015-01-01

    For over two decades, deep brain stimulation (DBS) has shown significant efficacy in treatment for refractory cases of dyskinesia, specifically in cases of Parkinson's disease and dystonia. DBS offers potential alleviation from symptoms through a well-tolerated procedure that allows personalized modulation of targeted neuroanatomical regions and related circuitries. For clinicians contending with how to provide patients with meaningful alleviation from often debilitating intractable disorders, DBSs titratability and reversibility make it an attractive treatment option for indications ranging from traumatic brain injury to progressive epileptic supra-synchrony. The expansion of our collective knowledge of pathologic brain circuitries, as well as advances in imaging capabilities, electrophysiology techniques, and material sciences have contributed to the expanding application of DBS. This review will examine the potential efficacy of DBS for neurologic and psychiatric disorders currently under clinical investigation and will summarize findings from recent animal models. PMID:26466888

  8. Leak detection with expandable coatings

    NASA Technical Reports Server (NTRS)

    1971-01-01

    Developed and evaluated is a system for leak detection that can be easily applied over separable connectors and that expands into a bubble or balloon if a leak is present. This objective is accomplished by using thin films of Parafilm tape wrapped over connectors, which are then overcoated with a special formulation. The low yield strength and the high elongation of the envelope permit bubble formation if leakage occurs. This system is appropriate for welds and other hardware besides separable connectors. The practical limit of this system appears to be for leaks exceeding 0.000001 cc/sec. If this envelope is used to trap gases for mass spectrometer inspection, leaks in the range of ten to the minus 8th power cc/sec. may be detectable.

  9. Preventive Ethics Through Expanding Education.

    PubMed

    Ho, Anita; MacDonald, Lisa Mei-Hwa; Unger, David

    2016-03-01

    Healthcare institutions have been making increasing efforts to standardize consultation methodology and to accredit both bioethics training programs and the consultants accordingly. The focus has traditionally been on the ethics consultation as the relevant unit of ethics intervention. Outcome measures are studied in relation to consultations, and the hidden assumption is that consultations are the preferred or best way to address day-to-day ethical dilemmas. Reflecting on the data from an internal quality improvement survey and the literature, we argue that having general ethics education as a key function of ethics services may be more important in meeting the contemporaneous needs of acute care settings. An expanded and varied ethics education, with attention to the time constraints of healthcare workers' schedules, was a key recommendation brought forward by survey respondents. Promoting ethical reflection and creating a culture of ethics may serve to prevent ethical dilemmas or mitigate their effects.

  10. Engelhard expands oxidation catalysts portfolio

    SciTech Connect

    Rotman, D.

    1997-02-26

    Engelhard says its agreement earlier this month to market Amoco Chemical`s proprietary maleic anhydride catalyst reflects an effort to expand its speciality catalysts business (CW, Feb. 19, p.5). In particular, the company says it is looking for additional alliances to bolster its oxidation catalysts portfolio. {open_quotes}There are some areas of oxidation catalysis that are reasonably attractive,{close_quotes} says Paul Lamb, marketing director/chemical catalysts. He says that while Engelhard is not interested in commodity oxidation catalysts, such as those used to make sulfuric acid, it does want to boost offerings for higher-value oxidation catalysts. Engelhard is collaborating with Geon to offer oxychlorination catalysts for making ethylene dichloride. It also markets oxidation catalysts for vinyl acetate production.

  11. Expanding Human Cognition and Communication

    SciTech Connect

    Spohrer, Jim; Pierce, Brian M.; Murray, Cherry A.; Golledge, Reginald G.; Horn, Robert E.; Turkle, Sherry; Yonas, Gerold; Glicken Turnley, Jessica; Pollack, Jordan; Burger, Rudy; Robinett, Warren; Wilson, Larry Todd; Bainbridge, W. S.; Canton, J.; Kuekes, P.; Loomis, J.; Penz, P.

    2013-01-01

    To be able to chart the most profitable future directions for societal transformation and corresponding scientific research, five multidisciplinary themes focused on major goals have been identified to fulfill the overall motivating vision of convergence described in the previous pages. The first, “Expanding Human Cognition and Communication,” is devoted to technological breakthroughs that have the potential to enhance individuals’ mental and interaction abilities. Throughout the twentieth century, a number of purely psychological techniques were offered for strengthening human character and personality, but evaluation research has generally failed to confirm the alleged benefits of these methods (Druckman and Bjork 1992; 1994). Today, there is good reason to believe that a combination of methods, drawing upon varied branches of converging science and technology, would be more effective than attempts that rely upon mental training alone.

  12. Expanding the Trilinos developer community.

    SciTech Connect

    Heroux, Michael Allen

    2010-10-01

    The Trilinos Project started approximately nine years ago as a small effort to enable research, development and ongoing support of small, related solver software efforts. The 'Tri' in Trilinos was intended to indicate the eventual three packages we planned to develop. In 2007 the project expanded its scope to include any package that was an enabling technology for technical computing. Presently the Trilinos repository contains over 55 packages covering a broad spectrum of reusable tools for constructing full-featured scalable scientific and engineering applications. Trilinos usage is now worldwide, and many applications have an explicit dependence on Trilinos for essential capabilities. Users come from other US laboratories, universities, industry and international research groups. Awareness and use of Trilinos is growing rapidly outside of Sandia. Members of the external research community are becoming more familiar with Trilinos, its design and collaborative nature. As a result, the Trilinos project is receiving an increasing number of requests from external community members who want to contribute to Trilinos as developers. To-date we have worked with external developers in an ad hoc fashion. Going forward, we want to develop a set of policies, procedures, tools and infrastructure to simplify interactions with external developers. As we go forward with multi-laboratory efforts such as CASL and X-Stack, and international projects such as IESP, we will need a more streamlined and explicit process for making external developers 'first-class citizens' in the Trilinos development community. This document is intended to frame the discussion for expanding the Trilinos community to all strategically important external members, while at the same time preserving Sandia's primary leadership role in the project.

  13. Production of biodiesel using expanded gas solvents

    SciTech Connect

    Ginosar, Daniel M; Fox, Robert V; Petkovic, Lucia M

    2009-04-07

    A method of producing an alkyl ester. The method comprises providing an alcohol and a triglyceride or fatty acid. An expanding gas is dissolved into the alcohol to form a gas expanded solvent. The alcohol is reacted with the triglyceride or fatty acid in a single phase to produce the alkyl ester. The expanding gas may be a nonpolar expanding gas, such as carbon dioxide, methane, ethane, propane, butane, pentane, ethylene, propylene, butylene, pentene, isomers thereof, and mixtures thereof, which is dissolved into the alcohol. The gas expanded solvent may be maintained at a temperature below, at, or above a critical temperature of the expanding gas and at a pressure below, at, or above a critical pressure of the expanding gas.

  14. Model of An Expanding Heliosphere

    NASA Astrophysics Data System (ADS)

    Song, P.; Vasyliunas, V. M.

    2015-12-01

    Conventional models of the heliosphere assume that the heliopause is formed, similarly to the magnetopause of a planet, at the location where the total pressure of the exterior (interstellar) medium is balanced by the total pressure of the interior (heliospheric) medium. The heliosphere, however, differs greatly from a planetary magnetosphere in being dominated by a continuous interior source of mass (present in some planetary magnetospheres, notably Jupiter and Saturn, but not to anything like the same extent), and it differs as well from systems with large interior mass sources such as comets (to which it has also been compared) in being threaded by magnetic flux from its central object (the Sun). The heliosphere must thus expand continually as more and more mass is put into it by the solar wind, with the heliopause marching into the interstellar medium at some non-zero speed while maintaining the plasma total (thermal plus magnetic) pressure equal to that of the interstellar medium. A steady state heliosphere is, strictly speaking, impossible unless and until the distinction between the heliospheric and the interstellar medium has disappeared. The geometry of the expansion can be visualized in different ways. Conventionally it is taken for granted that the expansion is deflected by interstellar flow sideways and channeled into an extended wake/tail region, the rest of the heliosphere being in apparently steady state. Even if this may occur, it would be at a distance much larger than commonly assumed. We explore the alternative possibility of a heliosphere expanding predominantly in the radial direction and describe some of its properties. The input from solar wind and interplanetary magnetic field during each solar cycle forms a shell, with subsequent cycles adding shells of alternating magnetic polarities. The ultimate extent of the heliosphere (in all directions) and the number of shells can be limited by the time until either the solar output or the

  15. Expanding discourse repertoires with hybridity

    NASA Astrophysics Data System (ADS)

    Kelly, Gregory J.

    2012-09-01

    In "Hybrid discourse practice and science learning" Kamberelis and Wehunt present a theoretically rich argument about the potential of hybrid discourses for science learning. These discourses draw from different forms of "talk, social practice, and material practices" to create interactions that are "intertextually complex" and "interactionally dynamic." The hybrid discourse practices are described as involving the dynamic interplay of at least three key elements: "the lamination of multiple cultural frames, the shifting relations between people and their discourse, and the shifting power relations between and among people." Each of these elements requires a respective unit of analysis and are often mutually reinforcing. The authors present a theoretically cogent argument for the study of hybrid discourse practices and identify the potential such discourses may have for science education. This theoretical development leads to an analysis of spoken and written discourse around a set of educational events concerning the investigation of owl pellets by two fifth grade students, their classmates, and teacher. Two discourse segments are presented and analyzed by the authors in detail. The first is a discourse analysis of the dissection of the owl pellet by two students, Kyle and Max. The second analysis examines the science report of these same two students. In this article, I pose a number of questions about the study with the hope that by doing so I expand the conversation around the insightful analysis presented.

  16. FPIA helps expand contraceptive services.

    PubMed

    Groot, H

    1984-01-01

    Since the beginning in 1971 of the Planned Parenthood Federation of America's international program, Family Planning International Assistance (FPIA), US$54 million has been contributed in direct financial support for the operation of over 300 family planning programs in 51 countries; over 3000 institutions in 115 countries have been supplied with family planning commodities, including over 600 million condoms, 120 cycles of oral contraceptives, and 4 million IUD; and about 1 million contraceptive clients were served by FPIA funded projects in 1982 aone. Since 1971, however, the world's population has increased from 3.7 billion to around 4.7 billion people. About 85 million people are added to the world each year. There is consensus that without organized family planning programs, today's world population would be even higher. FPIA measures its progress in terms of expanding the availability of contraceptive services in devloping countries. FPIA supported projects have helped make services available in areas previously lacking them, and has helped involve a wide variety of organizations, such as women's groups, youth organizations, and Red Cross Societies, in family planning services. A prime concern of FPIA, which has limited resources, is what happens to projects once FPIA support is terminated. FPIA has been paying attention to local income generation to help projects become more self-supporting and to increas staff members' management skills. The more successful income-generating schemes appear to be directly related to family planning, selling contraceptives and locally produced educational materials, and charging fees for family planning and related medical services and tuition for training courses. FPIA funded to projects use management by objectives (MBO) to help improve management skills. MBO helps grantees improve their ability to set objectives, plan, monitor, report, and do day-to-day project management.

  17. Improving and expanding NGO programmes.

    PubMed

    Mukhopadhyay, A

    1993-06-01

    India has massive problems and is in need of improving and expanding non governmental organization (NGO) programs by broadening the scope of NGO activities, identifying successful NGO activities, and by moving closer to the community to participate in their activities. The problems and experience in the last few decades indicate that with expansion bureaucratization takes place. The institution begins to depend on donors and follows donor-driven agendas. As more money is given by the government, many more so called GONGO or Government-NGO projects materialize. Another problem is that the government almost always approaches the NGOs for the implementation of a project, and there is complete lack of cooperation at the planning stage. The government is considering a loan from the World Bank and UNICEF to launch a mother and child health program, but there has not been any discussion with the dozens of people who have worked on issues concerning mother and child health issues for many years. There is a need to be more demanding of the government about the various programs that are implemented for the government. Very few NGO health and family welfare projects are run by ordinary nurses or ordinary Ayurvedic doctors under ordinary conditions. Since successful NGO work has to be extended to other parts of the country, they will have to be run by ordinary people with very ordinary resources. Over the years, the NGO community has become preoccupied with its own agenda. Today, despite very sophisticated equipment and infrastructure, they are not able to reach the 60,000-70,000 workers and employees. Some of the ideas with respect to the strengthens and weaknesses of community participation have to be shared. NGOs should include all the existing non governmental organizations throughout the country, and have a dialogue with other nongovernmental bodies such as trade unions. The challenge is to adjust the current agenda, prevailing style, and present way of operating and move

  18. Depth profiling of ultra trace metal impurities in polytetrafluoroethylene wares by surface scraping and acid-vapor extraction followed by ICP-MS analysis.

    PubMed

    Tanaka, Masafumi; Takahashi, Makoto

    2002-10-01

    This paper describes the development of the depth profiling method of ultra trace metal impurities in polytetrafluoroethylene (PTFE) wares based on contamination-free sampling followed by acid-vapor extraction and its application to evaluate the washing method for PTFE wares. A contamination-free sampling process was achieved by scraping the surface of PTFE wares with the cleft face of a silicon wafer followed by exposing the PTFE scraped to highly pure acid-vapor. The concentration of metal impurities in extractants was determined by ICP-MS equipped with an electrothermal vaporizer (ETV-ICP-MS). The blank values of Al, Cr, Fe, Ni and Cu by the depth profiling method were 0.006, 0.004, 0.005, 0.002 and 0.003 ng, respectively. By analyzing the depth profile of beakers, the distributions of ultra trace (ng g(-1) level) metal impurities were clarified. An examination of the washing methods by the depth profiling method also clarified that exposing to acid-vapor was more effective than the acid-dipping method for the elimination of metal impurities.

  19. Effect of polytetrafluoroethylene (PTFE) phase transition at 19°C on the use of Spectralon as a reference standard for reflectance.

    PubMed

    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 (<5%) measurements of flux, irradiance, or radiance are required from PTFE-based integrating spheres at temperatures close to the phase transition at 19°C. PMID:23852192

  20. Polymer dynamics near the surface and in the bulk of poly(tetrafluoroethylene) probed by zero-field muon-spin-relaxation spectroscopy.

    PubMed

    McKenzie, Iain; Salman, Zaher; Giblin, Sean R; Han, Yun Yu; Leach, Gary W; Morenzoni, Elvezio; Prokscha, Thomas; Suter, Andreas

    2014-02-01

    The results of many experiments on polymers such as polystyrene indicate that the polymer chains near a free surface exhibit enhanced dynamics when compared with the bulk. We have investigated whether this is the case for poly(tetrafluoroethylene) (PTFE) by using zero-field muon-spin-relaxation spectroscopy to characterize a local probe, the F-Mu(+)-F state, which forms when spin-polarized positive muons are implanted in PTFE. Low-energy muons (implantation energies from 2.0 to 23.0 keV) were used to study the F-Mu(+)-F state between ∼ 23 and 191 nm from the free surface of PTFE. Measurements were also made with surface muons (4.1 MeV) where the mean implantation depth is on the order of ∼ 0.6 mm. The relaxation rate of the F-Mu(+)-F state up to ∼ 150 K was found to be significantly higher for muons implanted at 2.0 keV than for higher implantation energies, which suggests that the polymer chains in a region on the order of a few tens of nanometers from the free surface are more mobile than those in the bulk.

  1. Polymer dynamics near the surface and in the bulk of poly(tetrafluoroethylene) probed by zero-field muon-spin-relaxation spectroscopy.

    PubMed

    McKenzie, Iain; Salman, Zaher; Giblin, Sean R; Han, Yun Yu; Leach, Gary W; Morenzoni, Elvezio; Prokscha, Thomas; Suter, Andreas

    2014-02-01

    The results of many experiments on polymers such as polystyrene indicate that the polymer chains near a free surface exhibit enhanced dynamics when compared with the bulk. We have investigated whether this is the case for poly(tetrafluoroethylene) (PTFE) by using zero-field muon-spin-relaxation spectroscopy to characterize a local probe, the F-Mu(+)-F state, which forms when spin-polarized positive muons are implanted in PTFE. Low-energy muons (implantation energies from 2.0 to 23.0 keV) were used to study the F-Mu(+)-F state between ∼ 23 and 191 nm from the free surface of PTFE. Measurements were also made with surface muons (4.1 MeV) where the mean implantation depth is on the order of ∼ 0.6 mm. The relaxation rate of the F-Mu(+)-F state up to ∼ 150 K was found to be significantly higher for muons implanted at 2.0 keV than for higher implantation energies, which suggests that the polymer chains in a region on the order of a few tens of nanometers from the free surface are more mobile than those in the bulk. PMID:25353500

  2. Papillaes-enhanced hydrophobicity of large-sized polytetrafluoroethylene-polyphenylene sulfite soft film prepared by layer-by-layer construction

    NASA Astrophysics Data System (ADS)

    Hou, Cheng Cheng; Wang, Wen Jun; Zhang, Yu; Guan, Zi Sheng

    2012-07-01

    Large-sized superhydrophobic soft film with hierarchical structures were prepared by combining papillaes on the polytetrafluoroethylene-polyphenylene sulfite (PTFE-PPS) surface via layer-by-layer construction on the glass substrate and heat treatment processes, therein, the papillaes were formed by 0.1 μm PTFE coated on the pollen grains. The water contact angles (CAs) and sliding angles (SAs) of the films are strongly dependent on the number density of the papillaes on the PTFE-PPS surface. A superhydrophobic surface with a water CA = 151.5° and SA = 4° was obtained when the number density was about 649 mm-2. The papillaes with micro/submicroscale structures play an important role in the formation of the superhydrophobic surface and can change Wenzel-type surface into Cassie-Baxter-type surface. The condensation of water vapor on the Cassie-Baxter-type PTFE-PPS film is much more difficult than that of on the Wenzel-type film. Our method may develop into a facile method to prepare large-sized soft film with low cost, which limited only by the size of the loading substrates.

  3. Expanding your horizons in science and mathematics

    NASA Technical Reports Server (NTRS)

    Palmer, Cynthia E. A.

    1995-01-01

    The purpose of the 'Expanding Your Horizons in Science and Mathematics' program is to interest young women in grades six through twelve in a variety of careers where mathematics and science are important. Progress in encouraging young women to take courses in mathematics, science, and technological subjects is discussed. Also included are adult, student, and organizational information packets used for 'Expanding Your Horizons' conferences.

  4. Screw expander for light duty diesel engines

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Preliminary selection and sizing of a positive displacement screw compressor-expander subsystem for a light-duty adiabatic diesel engine; development of a mathematical model to describe overall efficiencies for the screw compressor and expander; simulation of operation to establish overall efficiency for a range of design parameters and at given engine operating points; simulation to establish potential net power output at light-duty diesel operating points; analytical determination of mass moments of inertia for the rotors and inertia of the compressor-expander subsystem; and preparation of engineering layout drawings of the compressor and expander are discussed. As a result of this work, it was concluded that the screw compressor and expander designed for light-duty diesel engine applications are viable alternatives to turbo-compound systems, with acceptable efficiencies for both units, and only a moderate effect on the transient response.

  5. Time to Grow: Year Two Report on ExpandED Schools. A TASC Report

    ERIC Educational Resources Information Center

    Traill, Saskia; Brohawn, Katie

    2014-01-01

    An analysis of data from the second year of The After-School Corporation's (TASC's) national demonstration of an expanded school day for elementary and middle school students shows that ExpandED Schools improved school culture, decreased rates of students' chronic absenteeism and helped students develop positive learning habits and attitudes.…

  6. Emission of perfluoroalkyl carboxylic acids (PFCA) from heated surfaces made of polytetrafluoroethylene (PTFE) applied in food contact materials and consumer products.

    PubMed

    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 (<230°C), emissions from 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.

  7. An Expanded Classification of the Plant Kingdom.

    ERIC Educational Resources Information Center

    Rushton, B. S.

    1981-01-01

    Presents an expanded classification of the plant kingdom, emphasizing major evolutionary steps and differences in levels of complexity. Describes subdivisions and suggests that this classification, reflecting unity and diversity, may be logical, understandable, and useful to students. (JN)

  8. Injuries Soar as Trampoline Parks Expand

    MedlinePlus

    ... medlineplus.gov/news/fullstory_160184.html Injuries Soar as Trampoline Parks Expand Broken bones, fractures the most ... 1, 2016 MONDAY, Aug. 1, 2016 (HealthDay News) -- As trampoline parks spring up across the United States, ...

  9. Hand-Operated Hydraulic Tube Expander

    NASA Technical Reports Server (NTRS)

    Hagan, David W.; Wolff, Edwin D.

    1995-01-01

    Hand-operated tool expands end portion of narrow metal or plastic tube to slightly larger diameter. Used on tubes with original inner diameters as small as 0.060 in. Includes replaceable tip comprising ferrule and tubular expansion sleeve sized for sliding fit into tube to be expanded. Expansion sleeve swells in response to internal hydraulic pressure generated by turning handle and thereby advancing piston.

  10. Expanded Schools: Developing Mindsets to Support Academic Success. Research Brief

    ERIC Educational Resources Information Center

    ExpandED Schools, 2014

    2014-01-01

    The national demonstration of ExpandED Schools, The After-School Corporation's (TASC) expanded learning model, was launched in 2011-12 in New York City, Baltimore, and New Orleans. The ExpandED Schools demonstration is being evaluated by Policy Studies Associates (PSA) and is rolling out at a time when there is heightened awareness among…

  11. Multifunctional π-expanded oligothiophene macrocycles.

    PubMed

    Iyoda, Masahiko; Shimizu, Hideyuki

    2015-09-21

    This tutorial review summarizes recent progress in the design, synthesis, and multifunctional properties of fully conjugated macrocyclic π-systems. We focus on the π-expanded oligothiophene macrocycles after a short survey of macrocyclic conjugated loops and belts such as [n]cycloparaphenylenes, cyclic[n]para-phenylacetylenes, [4]cyclo-2,8-crysenylenes, and cyclo[n]thiophenes. Fully conjugated π-expanded oligothiophene macrocycles possess shape-persistent but sometimes pliable π-frames, and the electronic and optoelectronic properties of the macrocycles largely depend on the π-systems inserted into the oligothiophene macrocycles. Among them, the π-expanded oligothiophene macrocycle composed of 2,5-thienylenes, ethynylenes, and vinylenes is one of the most widely applicable macrocycles for constructing multifunctional π-systems. These π-expanded oligothiophene macrocycles from small to very large ring sizes can be prepared via a short step procedure, and their various solid state structures can be determined by X-ray analysis. Since these macrocycles have inner and outer domains, specific information concerning structural, electronic, and optical properties is expected. Furthermore, π-expanded oligothiophene macrocycles with alkyl substituents exhibit various morphologies depending on nanophase separation of molecules, and a morphological change is observed for the molecular switch. PMID:26204527

  12. Causes and consequences of expanded subventricular zones.

    PubMed

    Charvet, Christine J; Striedter, Georg F

    2011-09-01

    Primates have evolved an expanded isocortex relative to many other mammals. Parrots and songbirds have evolved an expanded telencephalon relative to many other birds. Previous work suggests that the expansion of the telencephalon in parrots and songbirds as well as the isocortex in primates is achieved, at least in part, by selectively delaying neurogenesis, expanding the subventricular zone (SVZ) and delaying maturation. The finding that similar developmental alterations in the spatial and temporal pattern of neurogenesis evolved together in these two distant lineages suggests that a single change in developmental mechanism might account for the expansion of the isocortex or telencephalon. We here review how uniformly lengthening developmental schedules may result in delays of neurogenesis, the expansion of the SVZ and delayed maturation. We propose that delays in neurogenesis may cause ventricular zone (VZ) cells to proliferate faster than the VZ can expand, which may force many proliferating cells to leave the VZ and form an expanded SVZ. Prolonged proliferation in the VZ and SVZ causes delays in neuronal maturation, which in turn may promote learning from conspecifics. Thus, we suggest that a single heterochronic change in developmental timing may orchestrate a variety of changes in the spatial and temporal pattern of proliferation, which has important behavioral consequences in adulthood.

  13. Toxicological evaluation of dry ice expanded tobacco.

    PubMed

    Theophilus, Eugenia H; Poindexter, Dale B; Meckley, Daniel R; Bombick, Betsy R; Borgerding, Michael F; Higuchi, Mark A; Ayres, Paul H; Morton, Michael J; Mosberg, Arnold T; Swauger, James E

    2003-11-30

    A tiered testing strategy has been developed to evaluate the potential of tobacco processes, ingredients, or technological developments to change the biological activity resulting from burning tobacco. The strategy is based on comparative chemical and biological testing. Dry ice expanded tobacco (DIET) is an example of a common tobacco expansion process currently used in the manufacture of cigarettes to increase tobacco filling capacity. As part of the toxicological evaluation of DIET, test cigarettes containing DIET were compared with control cigarettes containing tobacco expanded with a traditional expansion agent (Freon-11, also known as trichlorofluoromethane). Testing included mainstream cigarette smoke chemistry studies, genotoxicity studies (Ames and sister chromatid exchange, SCE), a 13-week inhalation study in Sprague-Dawley rats, and a 30-week dermal tumor promotion study in SENCAR mice. Cigarettes containing DIET or Freon-11 expanded tobacco were similar in biological activity. PMID:14581163

  14. DYNAMICAL MODEL OF AN EXPANDING SHELL

    SciTech Connect

    Pe'er, Asaf

    2012-06-10

    Expanding blast waves are ubiquitous in many astronomical sources, such as supernova remnants, X-ray emitting binaries, and gamma-ray bursts. I consider here the dynamics of such an expanding blast wave, both in the adiabatic and the radiative regimes. As the blast wave collects material from its surroundings, it decelerates. A full description of the temporal evolution of the blast wave requires consideration of both the energy density and the pressure of the shocked material. The obtained equation is different from earlier works in which only the energy was considered. The solution converges to the familiar results in both the ultrarelativistic and the sub-relativistic (Newtonian) regimes.

  15. Expanding your horizons in science and mathematics

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Through the presentation of its Expanding Your Horizons in Science and Mathematics career education conferences for secondary school young women, the Math/Science Network continues its efforts to remove the educational, psychological, and cultural barriers which prevent women from entering math-and science-based careers. The Expanding Your Horizons conferences were presented on 77 college, university and high school campuses across the United States. This year, these unique one day conferences reached 15,500 students, 3,000 parents and educators, and involved 3,000 career women who volunteered their services as conference planners, workshop leaders, speakers, and role models.

  16. Expanding Arts Education in a Digital Age

    ERIC Educational Resources Information Center

    Choi, Haeryun; Piro, Joseph M.

    2009-01-01

    This article proposes a way to expand the study of arts education within new contexts of technology and globalization. Drawing upon theories that have informed arts and aesthetic education in the past, the authors suggest new applications for these ideas to ensure that arts education sustains its significance in twenty-first-century society. The…

  17. Expanding Assessment Methods and Moments in History

    ERIC Educational Resources Information Center

    Frost, Jennifer; de Pont, Genevieve; Brailsford, Ian

    2012-01-01

    History courses at The University of Auckland are typically assessed at two or three moments during a semester. The methods used normally employ two essays and a written examination answering questions set by the lecturer. This study describes an assessment innovation in 2008 that expanded both the frequency and variety of activities completed by…

  18. Heat expanded starch-based compositions.

    PubMed

    Glenn, Gregory M; Klamczynski, Artur K; Holtman, Kevin M; Shey, Justin; Chiou, Bor-Sen; Berrios, Jose; Wood, Delilah; Orts, William J; Imam, Syed H

    2007-05-16

    A heat expansion process similar to that used for expanded bead polystyrene was used to expand starch-based compositions. Foam beads made by solvent extraction had the appearance of polystyrene beads but did not expand when heated due to an open-cell structure. Nonporous beads, pellets, or particles were made by extrusion or by drying and milling cooked starch slurries. The samples expanded into a low-density foam by heating 190-210 degrees C for more than 20 s at ambient pressures. Formulations containing starch (50-85%), sorbitol (5-15%), glycerol (4-12%), ethylene vinyl alcohol (EVAL, 5-15%), and water (10-20%) were studied. The bulk density was negatively correlated to sorbitol, glycerol, and water content. Increasing the EVAL content increased the bulk density, especially at concentrations higher than 15%. Poly(vinyl alcohol) (PVAL) increased the bulk density more than EVAL. The bulk density was lowest in samples made of wheat and potato starch as compared to corn starch. The expansion temperature for the starch pellets decreased more than 20 degrees C as the moisture content was increased from 10 to 25%. The addition of EVAL in the formulations decreased the equilibrium moisture content of the foam and reduced the water absorption during a 1 h soaking period.

  19. Expanded Learning the LA's BEST Way

    ERIC Educational Resources Information Center

    Sanger, Carla; Heckman, Paul E.

    2011-01-01

    As federal and state policymakers and many education researchers and experts suggest, expanding the learning day for students makes sense. Given the demographic trends--women increasingly entering the workforce and low-income families working multiple jobs--children and youth need supervision and opportunities to learn in the hours between 3:00…

  20. Properties of extruded expandable breadfruit products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dried breadfruit was extruded with a twin screw extruder to develop a value-added expanded fruit product. This research studied the effects of barrel temperature (120-160°C), moisture content (13-25%), feeding rate (13-25 kg/h) and screw speed (115-175rpm) on physicochemical properties (bulk densit...

  1. Expanded Subject Access to Reference Collection Materials.

    ERIC Educational Resources Information Center

    Mischo, William H.

    1979-01-01

    Reports a computer assisted index emphasizing expanded subject access to the reference collection of the Iowa State University Library. The index displays abbreviated length records and complements existing catalogs. Limitations of subject access and a system for assigning subject descriptors are discussed. (Author/RAA)

  2. Definition of Handicapping Conditions Expands ... Almost!

    ERIC Educational Resources Information Center

    Penning, Nick

    1990-01-01

    Recent efforts of parents, education experts, and Congress to expand the definition of handicapped children (under the Education for All Handicapped Children Act) to include attention deficit disorder victims failed when the National Association for the Advancement for Colored People intervened on behalf of Black children, already…

  3. Responsible implementation of expanded carrier screening

    PubMed Central

    Henneman, Lidewij; Borry, Pascal; Chokoshvili, Davit; Cornel, Martina C; van El, Carla G; Forzano, Francesca; Hall, Alison; Howard, Heidi C; Janssens, Sandra; Kayserili, Hülya; Lakeman, Phillis; Lucassen, Anneke; Metcalfe, Sylvia A; Vidmar, Lovro; de Wert, Guido; Dondorp, Wybo J; Peterlin, Borut

    2016-01-01

    This document of the European Society of Human Genetics contains recommendations regarding responsible implementation of expanded carrier screening. Carrier screening is defined here as the detection of carrier status of recessive diseases in couples or persons who do not have an a priori increased risk of being a carrier based on their or their partners' personal or family history. Expanded carrier screening offers carrier screening for multiple autosomal and X-linked recessive disorders, facilitated by new genetic testing technologies, and allows testing of individuals regardless of ancestry or geographic origin. Carrier screening aims to identify couples who have an increased risk of having an affected child in order to facilitate informed reproductive decision making. In previous decades, carrier screening was typically performed for one or few relatively common recessive disorders associated with significant morbidity, reduced life-expectancy and often because of a considerable higher carrier frequency in a specific population for certain diseases. New genetic testing technologies enable the expansion of screening to multiple conditions, genes or sequence variants. Expanded carrier screening panels that have been introduced to date have been advertised and offered to health care professionals and the public on a commercial basis. This document discusses the challenges that expanded carrier screening might pose in the context of the lessons learnt from decades of population-based carrier screening and in the context of existing screening criteria. It aims to contribute to the public and professional discussion and to arrive at better clinical and laboratory practice guidelines. PMID:26980105

  4. An Expanding Universe in the Classroom.

    ERIC Educational Resources Information Center

    Chandler, David

    1991-01-01

    Two computer-generated star charts that can be used as overlay transparencies to show an expanding universe are presented. Directions on how to use the star charts to determine the Hubble constant and the age of the universe are provided. (KR)

  5. 24 CFR 3285.502 - Expanding rooms.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 24 Housing and Urban Development 5 2014-04-01 2014-04-01 false Expanding rooms. 3285.502 Section 3285.502 Housing and Urban Development Regulations Relating to Housing and Urban Development (Continued) OFFICE OF ASSISTANT SECRETARY FOR HOUSING-FEDERAL HOUSING COMMISSIONER, DEPARTMENT OF HOUSING AND......

  6. Digital Storytelling: Expanding Media Possibilities for Learning

    ERIC Educational Resources Information Center

    McLellan, Hilary, Ed.

    2008-01-01

    Stories offer a powerful framework for engagement, reflection, and other important skills that young people need to learn. As digital media have expanded, so have the possibilities for creating stories. Here, several examples of those new possibilities are examined, examples that highlight student-produced online broadcasting initiatives,…

  7. Expanding CTE Opportunities through Blended Learning

    ERIC Educational Resources Information Center

    McKinstry, Elizabeth

    2012-01-01

    The global economy, 21st century skills, knowledge society, college and career readiness, digital and project-based learning are all common terms to educators who are expanding their learning environments beyond the classroom to meet the needs of all students. It is common knowledge that the rapid technological advances of this century have…

  8. Expanding Educational Excellence: The Power of Schools

    ERIC Educational Resources Information Center

    Coleman, Mary Ruth; Winn, Donna-Marie; Harradine, Christine

    2012-01-01

    In this paper, the authors explore four major barriers to academic success that must be addressed, briefly describe two projects that have worked to address these barriers, and make recommendations for moving forward as they work to expand educational excellence for all students. They provide examples of the myriad ways in which schools have the…

  9. Amorphous microcellular polytetrafluoroethylene foam film

    NASA Astrophysics Data System (ADS)

    Tang, Chongzheng

    1991-11-01

    We report herein the preparation of novel low-density ultramicrocellular fluorocarbon foams and their application. These fluorocarbon foams are of interest for the biochemistry arena in numerous applications including foodstuff, pharmacy, wine making, beer brewery, fermentation medical laboratory, and other processing factories. All of those require good quality processing programs in which, after eliminating bacterium and virus, compressed air is needed. Ordinarily, compressed air contains bacterium and virus, its size is 0.01 - 2 micrometers fluorocarbon foam films. Having average porous diameter 0.04 - 0.1 micrometers , these are stable to high temperature (280 degree(s)C) and chemical environments, and generally have good engineering and mechanical properties (e.g., low coefficient of thermal expansion, high modulus, and good dimensional stability). Our new process for preparing low density fluorocarbon foams provides materials with unique properties. As such, they offer the possibility for being superior to earlier materials for a number of the filter applications mentioned.

  10. Refrigeration generation using expander-generator units

    NASA Astrophysics Data System (ADS)

    Klimenko, A. V.; Agababov, V. S.; Koryagin, A. V.; Baidakova, Yu. O.

    2016-05-01

    The problems of using the expander-generator unit (EGU) to generate refrigeration, along with electricity were considered. It is shown that, on the level of the temperatures of refrigeration flows using the EGU, one can provide the refrigeration supply of the different consumers: ventilation and air conditioning plants and industrial refrigerators and freezers. The analysis of influence of process parameters on the cooling power of the EGU, which depends on the parameters of the gas expansion process in the expander and temperatures of cooled environment, was carried out. The schematic diagram of refrigeration generation plant based on EGU is presented. The features and advantages of EGU to generate refrigeration compared with thermotransformer of steam compressive and absorption types were shown, namely: there is no need to use the energy generated by burning fuel to operate the EGU; beneficial use of the heat delivered to gas from the flow being cooled in equipment operating on gas; energy production along with refrigeration generation, which makes it possible to create, using EGU, the trigeneration plants without using the energy power equipment. It is shown that the level of the temperatures of refrigeration flows, which can be obtained by using the EGU on existing technological decompression stations of the transported gas, allows providing the refrigeration supply of various consumers. The information that the refrigeration capacity of an expander-generator unit not only depends on the parameters of the process of expansion of gas flowing in the expander (flow rate, temperatures and pressures at the inlet and outlet) but it is also determined by the temperature needed for a consumer and the initial temperature of the flow of the refrigeration-carrier being cooled. The conclusion was made that the expander-generator units can be used to create trigeneration plants both at major power plants and at small energy.

  11. Smaragdyrins: emeralds of expanded porphyrin family.

    PubMed

    Pareek, Yogita; Ravikanth, M; Chandrashekar, T K

    2012-10-16

    Porphyrins are tetrapyrrolic 18 π electron conjugated macrocycles with wide applications that range from materials to medicine. Expanded porphyrins, synthetic analogues of porphyrins that contain more than 18 π electrons in the conjugated pathway, have an increased number of pyrroles or other heterocyles or multiple meso-carbon bridges. The expanded porphyrins have attracted tremendous attention because of unique features such as anion binding or transport that are not present in porphyrins. Expanded porphyrins exhibit wide applications that include their use in the coordination of large metal ions, as contrasting agents in magnetic resonance imaging (MRI), as sensitizers for photodynamic therapy (PDT) and as materials for nonlinear optical (NLO) studies. Pentaphyrin 1, sapphyrin 2, and smaragdyrin 3 are expanded porphyrins that include five pyrroles or heterocyclic rings. They differ from each other in the number of bridging carbons and direct bonds that connect the five heterocyclic rings. Sapphyrins were the first stable expanded porphyrins reported in the literature and remain one of the most extensively studied macrocycles. The strategies used to synthesize sapphyrins are well established, and these macrocycles are versatile anion binding agents. They possess rich porphyrin-like coordination chemistry and have been used in diverse applications. This Account reviews developments in smaragdyrin chemistry. Although smaragdyrins were discovered at the same time as sapphyrins, the chemistry of smaragdyrins remained underdeveloped because of synthetic difficulties and their comparative instability. Earlier efforts resulted in the isolation of stable β-substituted smaragdyrins and meso-aryl isosmaragdyrins. Recently, researchers have synthesized stable meso-aryl smaragdyrins by [3 + 2] oxidative coupling reactions. These results have stimulated renewed research interest in the exploration of these compounds for anion and cation binding, energy transfer

  12. Smaragdyrins: emeralds of expanded porphyrin family.

    PubMed

    Pareek, Yogita; Ravikanth, M; Chandrashekar, T K

    2012-10-16

    Porphyrins are tetrapyrrolic 18 π electron conjugated macrocycles with wide applications that range from materials to medicine. Expanded porphyrins, synthetic analogues of porphyrins that contain more than 18 π electrons in the conjugated pathway, have an increased number of pyrroles or other heterocyles or multiple meso-carbon bridges. The expanded porphyrins have attracted tremendous attention because of unique features such as anion binding or transport that are not present in porphyrins. Expanded porphyrins exhibit wide applications that include their use in the coordination of large metal ions, as contrasting agents in magnetic resonance imaging (MRI), as sensitizers for photodynamic therapy (PDT) and as materials for nonlinear optical (NLO) studies. Pentaphyrin 1, sapphyrin 2, and smaragdyrin 3 are expanded porphyrins that include five pyrroles or heterocyclic rings. They differ from each other in the number of bridging carbons and direct bonds that connect the five heterocyclic rings. Sapphyrins were the first stable expanded porphyrins reported in the literature and remain one of the most extensively studied macrocycles. The strategies used to synthesize sapphyrins are well established, and these macrocycles are versatile anion binding agents. They possess rich porphyrin-like coordination chemistry and have been used in diverse applications. This Account reviews developments in smaragdyrin chemistry. Although smaragdyrins were discovered at the same time as sapphyrins, the chemistry of smaragdyrins remained underdeveloped because of synthetic difficulties and their comparative instability. Earlier efforts resulted in the isolation of stable β-substituted smaragdyrins and meso-aryl isosmaragdyrins. Recently, researchers have synthesized stable meso-aryl smaragdyrins by [3 + 2] oxidative coupling reactions. These results have stimulated renewed research interest in the exploration of these compounds for anion and cation binding, energy transfer

  13. A new alternative to expandable pedicle screws: Expandable poly-ether-ether-ketone shell.

    PubMed

    Demir, Teyfik

    2015-05-01

    Screw pullout is a very common problem in the fixation of sacrum with pedicle screws. The principal cause of this problem is that the cyclic micro motions in the fixation of sacrum are higher than the other regions of the vertebrae that limit the osteo-integration between bone and screw. In addition to that, the bone quality is very poor at sacrum region. This study investigated a possible solution to the pullout problem without the expandable screws' handicaps. Newly designed poly-ether-ether-ketone expandable shell and classical pedicle screws were biomechanically compared. Torsion test, pullout tests, fatigue tests, flexion/extension moment test, axial gripping capacity tests and torsional gripping capacity tests were conducted in accordance with ASTM F543, F1798 and F1717. Standard polyurethane foam and calf vertebrae were used as embedding medium for pullout tests. Classical pedicle screw pullout load on polyurethane foam was 564.8 N compared to the failure load for calf vertebrae's 1264 N. Under the same test conditions, expandable poly-ether-ether-ketone shell system's pullout loads from polyurethane foam and calf vertebrae were 1196.3 and 1890 N, respectively. The pullout values for expandable poly-ether-ether-ketone shell were 33% and 53% higher than classical pedicle screw on polyurethane foam and calf vertebrae, respectively. The expandable poly-ether-ether-ketone shell exhibited endurance on its 90% of yield load. Contrary to poly-ether-ether-ketone shell, classical pedicle screw exhibited endurance on 70% of its yield load. Expandable poly-ether-ether-ketone shell exhibited much higher pullout performance than classical pedicle screw. Fatigue performance of expandable poly-ether-ether-ketone shell is also higher than classical pedicle screw due to damping the micro motion capacity of the poly-ether-ether-ketone. Expandable poly-ether-ether-ketone shell is a safe alternative to all other expandable pedicle screw systems on mechanical perspective.

  14. A new alternative to expandable pedicle screws: Expandable poly-ether-ether-ketone shell.

    PubMed

    Demir, Teyfik

    2015-05-01

    Screw pullout is a very common problem in the fixation of sacrum with pedicle screws. The principal cause of this problem is that the cyclic micro motions in the fixation of sacrum are higher than the other regions of the vertebrae that limit the osteo-integration between bone and screw. In addition to that, the bone quality is very poor at sacrum region. This study investigated a possible solution to the pullout problem without the expandable screws' handicaps. Newly designed poly-ether-ether-ketone expandable shell and classical pedicle screws were biomechanically compared. Torsion test, pullout tests, fatigue tests, flexion/extension moment test, axial gripping capacity tests and torsional gripping capacity tests were conducted in accordance with ASTM F543, F1798 and F1717. Standard polyurethane foam and calf vertebrae were used as embedding medium for pullout tests. Classical pedicle screw pullout load on polyurethane foam was 564.8 N compared to the failure load for calf vertebrae's 1264 N. Under the same test conditions, expandable poly-ether-ether-ketone shell system's pullout loads from polyurethane foam and calf vertebrae were 1196.3 and 1890 N, respectively. The pullout values for expandable poly-ether-ether-ketone shell were 33% and 53% higher than classical pedicle screw on polyurethane foam and calf vertebrae, respectively. The expandable poly-ether-ether-ketone shell exhibited endurance on its 90% of yield load. Contrary to poly-ether-ether-ketone shell, classical pedicle screw exhibited endurance on 70% of its yield load. Expandable poly-ether-ether-ketone shell exhibited much higher pullout performance than classical pedicle screw. Fatigue performance of expandable poly-ether-ether-ketone shell is also higher than classical pedicle screw due to damping the micro motion capacity of the poly-ether-ether-ketone. Expandable poly-ether-ether-ketone shell is a safe alternative to all other expandable pedicle screw systems on mechanical perspective

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

    PubMed Central

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

    2013-01-01

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

  16. Protein evolution with an expanded genetic code

    PubMed Central

    Liu, Chang C.; Mack, Antha V.; Tsao, Meng-Lin; Mills, Jeremy H.; Lee, Hyun Soo; Choe, Hyeryun; Farzan, Michael; Schultz, Peter G.; Smider, Vaughn V.

    2008-01-01

    We have devised a phage display system in which an expanded genetic code is available for directed evolution. This system allows selection to yield proteins containing unnatural amino acids should such sequences functionally outperform ones containing only the 20 canonical amino acids. We have optimized this system for use with several unnatural amino acids and provide a demonstration of its utility through the selection of anti-gp120 antibodies. One such phage-displayed antibody, selected from a naïve germline scFv antibody library in which six residues in VH CDR3 were randomized, contains sulfotyrosine and binds gp120 more effectively than a similarly displayed known sulfated antibody isolated from human serum. These experiments suggest that an expanded “synthetic” genetic code can confer a selective advantage in the directed evolution of proteins with specific properties. PMID:19004806

  17. Gas expander based power plant system

    SciTech Connect

    Kucerija, Z.

    1991-04-02

    This patent describes a method for generating electricity where gas pressure from a high pressure gas transmission line is reduced with a gas expander system capable of operating with fluctuating high pressure gas conditions and maintaining required outlet gas conditions for delivery to a lower pressure gas distribution line. It comprises supplying a portion of the lower pressure gas to the combustion apparatus of a steam generator, heating feedwater in the steam generator and producing a low pressure steam, condensing the steam in a heat exchange using the heat of condensation of the steam to heat a portion of high pressure gas in a heat exchange, mixing the heated high pressure gas with unheated high pressure gas in proportion to controlled variable requirements, reducing the pressure of the combined high pressure gas by passing the gas through a gas expander which produces useful shaft power for driving an electrical generator or for mechanical drive applications.

  18. Black holes in an expanding universe.

    PubMed

    Gibbons, Gary W; Maeda, Kei-ichi

    2010-04-01

    An exact solution representing black holes in an expanding universe is found. The black holes are maximally charged and the universe is expanding with arbitrary equation of state (P = w rho with -1 < or = for all w < or = 1). It is an exact solution of the Einstein-scalar-Maxwell system, in which we have two Maxwell-type U(1) fields coupled to the scalar field. The potential of the scalar field is an exponential. We find a regular horizon, which depends on one parameter [the ratio of the energy density of U(1) fields to that of the scalar field]. The horizon is static because of the balance on the horizon between gravitational attractive force and U(1) repulsive force acting on the scalar field. We also calculate the black hole temperature.

  19. Expanding Advanced Civilizations in the Universe

    NASA Astrophysics Data System (ADS)

    Gros, C.

    The 1950 lunch-table remark by Enrico Fermi `Where is everybody' has started intensive scientific and philosophical discussions about what we call nowadays the `Fermi paradox': If there had been ever a single advanced civilization in the cosmological history of our galaxy, dedicated to expansion, it would have had plenty of time to colonize the entire galaxy via exponential growth. No evidence of present or past alien visits to earth are known to us, leading to the standard conclusion that no advanced expanding civilization has ever existed in the milky-way. This conclusion rest fundamentally on the ad-hoc assumption, that any alien civilizations dedicated to expansion at one time would remain dedicated to expansions forever. Considering our limited knowledge about alien civilizations we need however to relax this basic assumption. Here we show that a substantial and stable population of expanding advanced civilization might consequently exist in our galaxy.

  20. Outsourcing meets expanded plant`s requirements

    SciTech Connect

    Haas, W.E.

    1997-03-01

    This article describes a system provided and operated by outside contractor that converts treated sewage water to high-purity makeup for expanded gas-turbine plant with minimal environmental impact. Florida Power Corp. (FPC), St. Petersburg, Fla., faced various challenges when planning to expand the Intercession City gas-turbine plant located near Kissimmee, Fla. One challenge was dealing with water for NO{sub x} emissions reduction supplied from the Kissimmee sanitary sewage treatment plant. Another was to minimize or eliminate wastewater generated by chemical cleaning of the reverse-osmosis (RO) system envisioned for the plant. Because of the substantial capital investment needed to meet these challenges, FPC outsourced the design, construction, and operation of the water treatment system to Ecolochem Inc., Norfolk, VA. After three years of operation, the system is meeting all design requirements and is saving the utility about $250,000/yr.

  1. Demands of Expanding Populations and Development Planning

    NASA Astrophysics Data System (ADS)

    Lim, Bo

    2010-04-01

    This book is a practical resource for development planners, demographers, and organizations involved with development projects related to improving the well-being and welfare of expanding human populations. Demands of Expanding Populations and Development Planning essentially is a treatment on sustainability and includes a heavy emphasis on major issues of environmental pollution over the last 3 decades. The book's coverage of ecosystems, atmospheric chemistry, water availability and quality, and soils is comprehensive. The author's extensive teaching experience makes this somewhat of an authoritative book on air quality and emissions from natural and anthropogenic sources, volatile heavy metals, carbon monoxide, radon, and nuclear waste. Most of the book focuses on the atmospheric chemistry of air pollution, whether the pollution source is from energy, industrial production, and manufacturing processes or from the treatment of waste products from such processes.

  2. Anaerobic expanded bed treatment of whey

    SciTech Connect

    Switzenbaum, M.S.; Danskin, S.C.

    1982-01-01

    The use of anaerobic attached film expanded bed (AAFEB) for whey treatment is described and the potential for implementation of substitute natural gas from whey is discussed. A significant portion (less than or equal to 46%) of the energy needs at cheese-production plants could be recovered by CH/sub 4/ manufactured from whey. Efficient treatment of whey is possible by AAFEB at low retention times and at high organic loading rates.

  3. Short wavelength striations on expanding plasma clouds

    SciTech Connect

    Winske, D.; Gary, S.P.

    1989-01-01

    The growth and evolution of short wavelength (expanding across an ambient magnetic field have been actively studied in recent years, both by means of experiments in the laboratory as well as in space and through numerical simulations. We review the relevant observations and simulations results, discuss the instability mechanism and related linear theory, and describe recent work to bring experiments and theory into better agreement. 30 refs., 6 figs.

  4. Joule-Thomson expander and heat exchanger

    NASA Technical Reports Server (NTRS)

    Norman, R. H.

    1976-01-01

    The Joule-Thomson Expander and Heat Exchanger Program was initiated to develop an assembly (JTX) which consists of an inlet filter, counterflow heat exchanger, Joule-Thomson expansion device, and a low pressure jacket. The program objective was to develop a JTX which, when coupled to an open cycle supercritical helium refrigerating system (storage vessel), would supply superfluid helium (He II) at 2 K or less for cooling infrared detectors.

  5. Measurements of an expanding surface flashover plasma

    SciTech Connect

    Harris, J. R.

    2014-05-21

    A better understanding of vacuum surface flashover and the plasma produced by it is of importance for electron and ion sources, as well as advanced accelerators and other vacuum electronic devices. This article describes time-of-flight and biased-probe measurements made on the expanding plasma generated from a vacuum surface flashover discharge. The plasma expanded at velocities of 1.2–6.5 cm/μs, and had typical densities of 10{sup 10}–10{sup 12} cm{sup −3}. The expansion velocity of the plasma leading edge often exhibited a sharp increase at distances of about 50 mm from the discharge site. Comparison with biased-probe data suggests that, under most conditions, the plasma leading edge was dominated by negative ions, with the apparent increase in velocity being due to fast H{sup −} overtaking slower, heavier ions. In some cases, biased-probe data also showed abrupt discontinuities in the plasma energy distribution co-located with large changes in the intercepted plasma current, suggesting the presence of a shock in the leading edge of the expanding plasma.

  6. Lubricin in human breast tissue expander capsules.

    PubMed

    Cheriyan, Thomas; Guo, Lifei; Orgill, Dennis P; Padera, Robert F; Schmid, Thomas M; Spector, Myron

    2012-10-01

    Capsular contraction is the most common complication of breast reconstruction surgery. While presence of the contractile protein alpha smooth muscle actin (α-SMA) is considered among the causes of capsular contraction, the exact etiology and pathophysiology is not fully understood. The objective of this study was to investigate the possible role of lubricin in capsular formation and contraction by determining the presence and distribution of the lubricating protein lubricin in human breast tissue expander capsules. Related aims were to evaluate select histopathologic features of the capsules, and the percentage of cells expressing α-SMA, which reflects the myofibroblast phenotype. Capsules from tissue expanders were obtained from eight patients. Lubricin, at the tissue-implant interface, in the extracellular matrix, and in cells, and α-SMA-containing cells were evaluated immunohistochemically. The notable finding was that lubricin was identified in all tissue expander capsules: as a discrete layer at the tissue-implant interface, extracellular, and intracellular. There was a greater amount of lubricin in the extracellular matrix in the intimal-subintimal zone when compared with the tissue away from the implant. Varying degrees of synovial metaplasia were seen at the tissue-implant interface. α-SMA-containing cells were also seen in all but one patient. The findings might help us better understand factors involved in capsule formation.

  7. Expandable Metal Liner For Downhole Components

    DOEpatents

    Hall, David R.; Fox, Joe R.

    2004-10-05

    A liner for an annular downhole component is comprised of an expandable metal tube having indentations along its surface. The indentations are formed in the wall of the tube either by drawing the tube through a die, by hydroforming, by stamping, or roll forming and may extend axially, radially, or spirally along its wall. The indentations accommodate radial and axial expansion of the tube within the downhole component. The tube is inserted into the annular component and deformed to match an inside surface of the component. The tube may be expanded using a hydroforming process or by drawing a mandrel through the tube. The tube may be expanded in such a manner so as to place it in compression against the inside wall of the component. The tube is useful for improving component hydraulics, shielding components from contamination, inhibiting corrosion, and preventing wear to the downhole component during use. It may also be useful for positioning conduit and insulated conductors within the component. An insulating material may be disposed between the tube and the component in order to prevent galvanic corrosion of the downhole component.

  8. Expanded mode lasers for telecommunications applications

    NASA Astrophysics Data System (ADS)

    Lealman, Ian F.

    This thesis describes the development of a long wavelength (1.55 μm) expanded mode semiconductor laser. The increased spot size of the laser improves both the coupling efficiency to cleaved fibre and fibre alignment tolerances and reduces packaging cost. In this type of device the strength of the waveguide is gradually reduced towards the front facet allowing the mode to adiabatically expand so that the laser mode is better matched in size to that of a cleaved fibre. This can be achieved by either reducing the refractive index of the guide or reducing the amount of material in the core. The structure chosen was a buried heterostructure laser that utilised a twin guide consisting of an upper higher refractive index guide (the active region of the laser) above a weak passive guide. The width of the active region was reduced along part of the device allowing the mode to expand into the weak underlying guide. The guide structure was optimised using a variable grid finite difference mode solver, and the taper length calculated by an approximation to Love's method. Detailed results are presented for the measured light-current characteristic, farfield and coupling loss to cleaved fibre. These coupling losses were compared to the calculated data thus allowing the waveguide design to be optimised. Several iterations in the design of the device were undertaken, with the aim of reducing the coupling loss to cleaved single mode fibre without significantly compromising the laser performance. The final device design had extremely low coupling losses as low as 1.2 dB to cleaved fibre. Finally, the positive impact this device had on passive alignment using a silicon motherboard is examined, and the application this technology to a range of other optoelectronic components is discussed.

  9. Expandable tubulars for use in geologic structures

    DOEpatents

    Spray, Jeffery A.; Svedeman, Steven; Walter, David; Mckeighan, Peter; Siebanaler, Shane; Dewhurst, Peter; Hobson, Steven; Foss, Doug; Wirz, Holger; Sharpe, Aaron; Apostal, Michael

    2014-08-12

    An expandable tubular includes a plurality of leaves formed from sheet material that have curved surfaces. The leaves extend around a portion or fully around the diameter of the tubular structure. Some of the adjacent leaves of the tubular are coupled together. The tubular is compressed to a smaller diameter so that it can be inserted through previously deployed tubular assemblies. Once the tubular is properly positioned, it is deployed and coupled or not coupled to a previously deployed tubular assembly. The tubular is useful for all types of wells and boreholes.

  10. Entangling power of an expanding universe

    SciTech Connect

    Steeg, Greg Ver; Menicucci, Nicolas C.

    2009-02-15

    We show that entanglement can be used to detect spacetime curvature. Quantum fields in the Minkowski vacuum are entangled with respect to local field modes. This entanglement can be swapped to spatially separated quantum systems using standard local couplings. A single, inertial field detector in the exponentially expanding (de Sitter) vacuum responds as if it were bathed in thermal radiation in a Minkowski universe. We show that using two inertial detectors, interactions with the field in the thermal case will entangle certain detector pairs that would not become entangled in the corresponding de Sitter case. The two universes can thus be distinguished by their entangling power.

  11. Emergence of oscillons in an expanding background

    SciTech Connect

    Farhi, E.; Guth, A. H.; Iqbal, N.; Graham, N.; Rosales, R. R.; Stamatopoulos, N.

    2008-04-15

    We consider a (1+1) dimensional scalar field theory that supports oscillons, which are localized, oscillatory, stable solutions to nonlinear equations of motion. We study this theory in an expanding background and show that oscillons now lose energy, but at a rate that is exponentially small when the expansion rate is slow. We also show numerically that a universe that starts with (almost) thermal initial conditions will cool to a final state where a significant fraction of the energy of the universe--on the order of 50%--is stored in oscillons. If this phenomenon persists in realistic models, oscillons may have cosmological consequences.

  12. Painful Na-channelopathies: an expanding universe.

    PubMed

    Waxman, Stephen G

    2013-07-01

    The universe of painful Na-channelopathies--human disorders caused by mutations in voltage-gated sodium channels--has recently expanded in three dimensions. We now know that mutations of sodium channels cause not only rare genetic 'model disorders' such as inherited erythromelalgia and channelopathy-associated insensitivity to pain but also common painful neuropathies. We have learned that mutations of NaV1.8, as well as mutations of NaV1.7, can cause painful Na-channelopathies. Moreover, recent studies combining atomic level structural models and pharmacogenomics suggest that the goal of genomically guided pain therapy may not be unrealistic.

  13. Short wavelength striations on expanding plasma clouds

    NASA Technical Reports Server (NTRS)

    Winske, D.; Gary, S. P.

    1990-01-01

    The present evaluation of current understanding of the growth and evolution of less-than-1 ion gyroradius 'flute modes' on a plasma as it expands across and ambient magnetic field notes that the mechanism by which the instability is generated, and its approximate linear theory (encompassing nonlocal, finite-beta, and collisional effects), have reached a satisfactory degree of development. AMPTE Ba releases have been the bases of most of the observational studies. Substantial progress is also noted in the development of a nonlinear mode-coupling theory which can resolve remaining differences between theory and observation.

  14. Expanding health literacy: indigenous youth creating videos.

    PubMed

    Stewart, Suzanne; Riecken, Ted; Scott, Tish; Tanaka, Michele; Riecken, Janet

    2008-03-01

    How can creating videos contribute to expanding health literacy? This article describes a participatory action research project with a group of Canadian Indigenous youth and their teachers. As the youth explored their interests about health and wellness through the artistic creation of videos, they developed a critical consciousness about community, culture, confidence, and control. They became mobilized and obtained information about health and wellness that allowed for the development and expansion of their notion of health literacy that included cultural conceptions of health and wellness.

  15. Expanding NASA Science Cooperation with New Partners

    NASA Astrophysics Data System (ADS)

    Allen, Marc; Bress, Kent

    Expanding NASA Science Cooperation with New Partners When NASA was created in 1958, it was given a goal of "cooperation by the United States with other nations and groups of nations in work done pursuant to this Act and in the peaceful application of the results." As science has become increasingly globalized during the past 50 years, NASA and its many partners in space and Earth science research have benefited enormously from pooling ideas, skills, and resources for joint undertakings. The discoveries made have powerfully advanced public awareness of science and its importance all over the world. Today, the U.S. Administra-tion is encouraging NASA to expand its cooperation with new and emerging partners. NASA space and Earth science cooperation is founded on scientist-to-scientist research collaboration. Space missions are very costly and technically challenging, but there are many other important areas for international cooperation. Areas ripe for expansion with new partners include space data sharing, scientist-to-scientist collaborative research, international research program plan-ning and coordination, Earth applications for societal benefit, ground-based measurements for Earth system science, and education and public outreach. This presentation lays out NASA's general principles for international science cooperation, briefly describes each of these opportu-nity areas, and suggests avenues for initiating new cooperative relationships.

  16. Unintended Consequences of Expanding the Genetic Alphabet.

    PubMed

    Pollum, Marvin; Ashwood, Brennan; Jockusch, Steffen; Lam, Minh; Crespo-Hernández, Carlos E

    2016-09-14

    The base pair d5SICS·dNaM was recently reported to incorporate and replicate in the DNA of a modified strain of Escherichia coli, thus making the world's first stable semisynthetic organism. This newly expanded genetic alphabet may allow organisms to store considerably more information in order to translate proteins with unprecedented enzymatic activities. Importantly, however, there is currently no knowledge of the photochemical properties of d5SICS or dNaM-properties that are central to the chemical integrity of cellular DNA. In this contribution, it is shown that excitation of d5SICS or dNaM with near-visible light leads to efficient trapping of population in the nucleoside's excited triplet state in high yield. Photoactivation of these long-lived, reactive states is shown to photosensitize cells, leading to the generation of reactive oxygen species and to a marked decrease in cell proliferation, thus warning scientists of the potential phototoxic side effects of expanding the genetic alphabet. PMID:27564795

  17. Historical Notes on the Expanding Universe

    NASA Technical Reports Server (NTRS)

    Way, Michael J.; Belenkyi, Ari; Nussbaumer, Harry; Peacock, John

    2014-01-01

    The article Measuring the Hubble constant by Mario Livio and Adam Riess (Physics Today, October 2013, page 41) reviewed studies of the expanding universe from the 1920s to the present. Although the history of the subject underwent considerable compression to fit the length of a magazine article, we think it may leave a misleading impression of some of the key steps to our current understanding. We therefore offer the following clarifications. Most significantly, papers by Arthur Eddington and by Willem de Sitter in 1930, who successfully promoted Georges Lematres 1927 article for the Scientific Society of Brussels, effected a paradigm shift in interpretation of extragalactic redshifts in 1930. Before then, the astronomical community was generally unaware of the existence of nonstatic cosmological solutions and did not broadly appreciate that redshifts could be thought of locally as Doppler shifts in an expanding matter distribution. Certainly, in 1929 Edwin Hubble referred only to the de Sitter solution of 1917. At the time, the relation between distance and redshift predicted in that model was generally seen purely as a manifestation of static spacetime curvature.

  18. Space power for an expanded vision.

    NASA Astrophysics Data System (ADS)

    Braselton, W. M., Jr.

    1995-03-01

    The author suggests that the problem with the space program in the 1990s is that there are few short term benefits that the public can directly relate to and no long term vision that will motivate them. Recent surveys have shown that public would support an expanded space program if they understood the specific short term purpose that provides benefits coupled to a longer term vision. The author discusses a proposed space program that has a 100 Year Vision and a specific beneficial near term purpose. The specific near term purpose is to return to the Moon and develop He for nuclear fusion power on Earth, and then expand into the Solar System and eventually to the nearby stars with the purpose of finding new life as a long term vision. This is how the author sees it unfolding-in three Epochs. Epoch I is proposed as the minimum near term space program. Space Station Freedom in near-Earth orbit being serviced by the Space Shuttle, the National Aerospace Plane and the Single-Stage-To-Orbit Vehicle. Just above Freedom is an Earth Observing System Satellite that, as part of Mission to Planet Earth, will monitor and analyze our planet's ecological systems. There are also a great many scientific, defense and launch systems whose technologies will evolve to play critical roles in future epochs.

  19. Optical cavity resonator in an expanding universe

    NASA Astrophysics Data System (ADS)

    Kopeikin, Sergei M.

    2015-02-01

    We study the cosmological evolution of frequency of a standing electromagnetic wave in a resonant optical cavity placed to the expanding manifold described by the Robertson-Walker metric. Because of the Einstein principle of equivalence (EEP), one can find a local coordinate system (a local freely falling frame), in which spacetime is locally Minkowskian. However, due to the conformal nature of the Robertson-Walker metric the conventional transformation to the local inertial coordinates introduces ambiguity in the physical interpretation of the local time coordinate, . Therefore, contrary to a common-sense expectation, a straightforward implementation of EEP alone does not allow us to unambiguously decide whether atomic clocks based on quantum transitions of atoms, ticks at the same rate as the clocks based on electromagnetic modes of a cavity. To resolve this ambiguity we have to analyse the cavity rigidity and the oscillation of its electromagnetic modes in an expanding universe by employing the full machinery of the Maxwell equations irrespectively of the underlying theory of gravity. We proceed in this way and found out that the size of the cavity and the electromagnetic frequency experience an adiabatic drift in conformal (unphysical) coordinates as the universe expands in accordance with the Hubble law. We set up the oscillation equation for the resonant electromagnetic modes, solve it by the WKB approximation, and reduce the coordinate-dependent quantities to their counterparts measured by a local observer who counts time with atomic clock. The solution shows that there is a perfect mutual cancellation of the adiabatic drift of cavity's frequency by space transformation to local coordinates and the time counted by the clocks based on electromagnetic modes of cavity has the same rate as that of atomic clocks. We conclude that if general relativity is correct and the local expansion of space is isotropic there should be no cosmological drift of frequency of a

  20. The Expanding Marketplace for Applied Geophysics

    NASA Astrophysics Data System (ADS)

    Carlson, N.; Sirles, P.

    2012-12-01

    While the image of geophysics for the proverbial "layman" often seems limited to volcanoes and earthquakes, and to the geoscientist this image enlarges to include oil or minerals exploration and whole earth studies, there has been a steady increase in the application of geophysics into the realm of "daily life", such as real estate deals, highway infrastructure, and flood protection. This expansion of applications can be attributed to the improved economics from advances in equipment and interpretation. Traditional geophysical methods that at one time often only fit within the budgets of oil, gas, and minerals exploration programs can now be economically applied to much smaller scale needs like contaminant mapping, landfill delineation, and levee investigations. A real-world, economic example of this expanding marketplace is our company, which began very small and was aimed almost exclusively at the minerals exploration market. Most of our growth has been in the last 10 years, when we have expanded to five offices and a staff with almost 40 geoscientist degrees (21 in geophysics); much of this growth has been in the non-oil, non-minerals arenas. While much of our work still includes minerals exploration, other projects this year include wind-farm foundation studies, cavity detection above underground nuclear tests, landfill studies, acid mine drainage problems, and leaks in evaporation ponds. A methodology example of this expanding market is the induced polarization (IP) survey, once primarily used for minerals exploration, particularly large porphyry copper deposits, but now efficient enough to also use in environmental studies. The IP method has been particularly useful in delineating and characterizing old, poorly documented landfills, and recent research suggests it may also be useful in monitoring the accelerated biodegradation processes used in some cases to rehabilitate the sites. Compared to temperature monitoring systems, IP may be more useful in providing

  1. 46 CFR 56.30-15 - Expanded or rolled joints.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Expanded or rolled joints. 56.30-15 Section 56.30-15... APPURTENANCES Selection and Limitations of Piping Joints § 56.30-15 Expanded or rolled joints. (a) Expanded or rolled joints may be used where experience or test has demonstrated that the joint is suitable for...

  2. 46 CFR 56.30-15 - Expanded or rolled joints.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Expanded or rolled joints. 56.30-15 Section 56.30-15... APPURTENANCES Selection and Limitations of Piping Joints § 56.30-15 Expanded or rolled joints. (a) Expanded or rolled joints may be used where experience or test has demonstrated that the joint is suitable for...

  3. 46 CFR 56.30-15 - Expanded or rolled joints.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Expanded or rolled joints. 56.30-15 Section 56.30-15... APPURTENANCES Selection and Limitations of Piping Joints § 56.30-15 Expanded or rolled joints. (a) Expanded or rolled joints may be used where experience or test has demonstrated that the joint is suitable for...

  4. 26 CFR 1.199-7 - Expanded affiliated groups.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 3 2010-04-01 2010-04-01 false Expanded affiliated groups. 1.199-7 Section 1... (CONTINUED) INCOME TAXES Itemized Deductions for Individuals and Corporations (continued) § 1.199-7 Expanded... the Internal Revenue Code (Code). All members of an expanded affiliated group (EAG) are treated as...

  5. 26 CFR 1.199-7 - Expanded affiliated groups.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 3 2011-04-01 2011-04-01 false Expanded affiliated groups. 1.199-7 Section 1...-7 Expanded affiliated groups. (a) In general. The provisions of this section apply solely for purposes of section 199 of the Internal Revenue Code (Code). All members of an expanded affiliated...

  6. 26 CFR 1.199-7 - Expanded affiliated groups.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 3 2012-04-01 2012-04-01 false Expanded affiliated groups. 1.199-7 Section 1...-7 Expanded affiliated groups. (a) In general. The provisions of this section apply solely for purposes of section 199 of the Internal Revenue Code (Code). All members of an expanded affiliated...

  7. 26 CFR 1.199-7 - Expanded affiliated groups.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 26 Internal Revenue 3 2013-04-01 2013-04-01 false Expanded affiliated groups. 1.199-7 Section 1...-7 Expanded affiliated groups. (a) In general. The provisions of this section apply solely for purposes of section 199 of the Internal Revenue Code (Code). All members of an expanded affiliated...

  8. 26 CFR 1.199-7 - Expanded affiliated groups.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 26 Internal Revenue 3 2014-04-01 2014-04-01 false Expanded affiliated groups. 1.199-7 Section 1...-7 Expanded affiliated groups. (a) In general. The provisions of this section apply solely for purposes of section 199 of the Internal Revenue Code (Code). All members of an expanded affiliated...

  9. 21 CFR 884.4250 - Expandable cervical dilator.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Expandable cervical dilator. 884.4250 Section 884....4250 Expandable cervical dilator. (a) Identification. An expandable cervical dilator is an instrument with two handles and two opposing blades used manually to dilate (stretch open) the cervical os....

  10. 21 CFR 884.4250 - Expandable cervical dilator.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Expandable cervical dilator. 884.4250 Section 884....4250 Expandable cervical dilator. (a) Identification. An expandable cervical dilator is an instrument with two handles and two opposing blades used manually to dilate (stretch open) the cervical os....

  11. 21 CFR 884.4250 - Expandable cervical dilator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Expandable cervical dilator. 884.4250 Section 884....4250 Expandable cervical dilator. (a) Identification. An expandable cervical dilator is an instrument with two handles and two opposing blades used manually to dilate (stretch open) the cervical os....

  12. 21 CFR 884.4250 - Expandable cervical dilator.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Expandable cervical dilator. 884.4250 Section 884....4250 Expandable cervical dilator. (a) Identification. An expandable cervical dilator is an instrument with two handles and two opposing blades used manually to dilate (stretch open) the cervical os....

  13. 21 CFR 884.4250 - Expandable cervical dilator.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Expandable cervical dilator. 884.4250 Section 884....4250 Expandable cervical dilator. (a) Identification. An expandable cervical dilator is an instrument with two handles and two opposing blades used manually to dilate (stretch open) the cervical os....

  14. Wave Propagation in Expanding Cell Layers

    NASA Astrophysics Data System (ADS)

    Utuje, Kazage J. Christophe; Banerjee, Shiladitya; Marchetti, M. Cristina

    2014-03-01

    The coordinated migration of groups of cells drives important biological processes, such as wound healing and morphogenesis. In this talk we present a minimal continuum model of an expanding cell monolayer coupling elastic deformations to myosin-based activity in the cells. The myosin-driven contractile activity is quantified by the chemical potential difference for the process of ATP hydrolysis by myosin motors. A new ingredient of the model is a feedback of the local strain rate of the monolayer on contractility that naturally yields a mechanism for viscoelasticity of the cellular medium. By combining analytics and numerics we show that this simple model reproduces qualitatively many experimental findings, including the build-up of contractile stresses at the center of the cell monolayer, and the existence of traveling mechanical waves that control spreading dynamics and stress propagation in the cell monolayer. KJCU and MCM were supported by the NSF through grants DMR-1004789 and DGE-1068780.

  15. Expandable mixing section gravel and cobble eductor

    DOEpatents

    Miller, Arthur L.; Krawza, Kenneth I.

    1997-01-01

    In a hydraulically powered pump for excavating and transporting slurries in hich it is immersed, the improvement of a gravel and cobble eductor including an expandable mixing section, comprising: a primary flow conduit that terminates in a nozzle that creates a water jet internal to a tubular mixing section of the pump when water pressure is applied from a primary supply flow; a tubular mixing section having a center line in alignment with the nozzle that creates a water jet; a mixing section/exit diffuser column that envelopes the flexible liner; and a secondary inlet conduit that forms an opening at a bas portion of the column and adjacent to the nozzle and water jet to receive water saturated gravel as a secondary flow that mixes with the primary flow inside of the mixing section to form a combined total flow that exits the mixing section and decelerates in the exit diffuser.

  16. Microfluidics Expanding the Frontiers of Microbial Ecology

    PubMed Central

    Rusconi, Roberto; Garren, Melissa; Stocker, Roman

    2014-01-01

    The ability afforded by microfluidics to observe the behaviors of microbes in highly controlled and confined microenvironments, across scales from a single cell to mixed communities, has significantly contributed to expand the frontiers of microbial ecology over the last decade. Spatially and temporally varying distributions of organisms and chemical cues that mimic natural microbial habitats can now be established by exploiting physics at the micrometer scale and by incorporating structures with specific geometries and materials. Here we review applications of microfluidics that have resulted in highly insightful discoveries on fundamental aspects of microbial life, ranging from growth and sensing to cell-cell interactions and population dynamics. We anticipate that this flexible, multidisciplinary technology will continue to facilitate discoveries regarding the ecology of microorganisms and help uncover strategies to control phenomena such as biofilm formation and antibiotic resistance. PMID:24773019

  17. The expanding spectrum of cutaneous borreliosis.

    PubMed

    Eisendle, K; Zelger, B

    2009-04-01

    The known spectrum of skin manifestations in cutaneous Lyme disease is continuously expanding and can not be regarded as completed. Besides the classical manifestations of cutaneous borreliosis like erythema (chronicum) migrans, borrelial lymphocytoma and acrodermatitis chronica atrophicans evidence is growing that at least in part also other skin manifestations, especially morphea, lichen sclerosus and cases of cutaneous B-cell lymphoma are causally related to infections with Borrelia. Also granuloma annulare and interstitial granulomatous dermatitis might be partly caused by Borrelia burgdorferi or similar strains. There are also single reports of other skin manifestations to be associated with borrelial infections like cutaneous sarcoidosis, necrobiosis lipoidica and necrobiotic xanthogranuloma. In addition, as the modern chameleon of dermatology, cutaneous borreliosis, especially borrelial lymphocytoma, mimics other skin conditions, as has been shown for erythema annulare centrifugum or lymphocytic infiltration (Jessner Kanof) of the skin. PMID:19357623

  18. Web Content Analysis: Expanding the Paradigm

    NASA Astrophysics Data System (ADS)

    Herring, Susan C.

    Are established methods of content analysis (CA) adequate to analyze web content, or should new methods be devised to address new technological developments? This article addresses this question by contrasting narrow and broad interpretations of the concept of web content analysis. The utility of a broad interpretation that subsumes the narrow one is then illustrated with reference to research on weblogs (blogs), a popular web format in which features of HTML documents and interactive computer-mediated communication converge. The article concludes by proposing an expanded Web Content Analysis (WebCA) paradigm in which insights from paradigms such as discourse analysis and social network analysis are operationalized and implemented within a general content analytic framework.

  19. Emergency management: expanding the disaster plan.

    PubMed

    Ross, Kevin L; Bing, Caryn M

    2007-06-01

    A comprehensive emergency management plan (CEMP) is key to minimizing the disruption of patient care and services during and after a natural or man-made disaster. The home health nurse can play a key role in enhancing, expanding, and evaluating the effectiveness of the organization's disaster plan. The components of a CEMP and lessons learned from actual implementation of disaster plans in home care are addressed. The disasters and emergencies of the past few years, such as threats of terrorism, hurricanes, floods, wildfires, tornadoes, and earthquakes, have validated the need to extend the emergency preparedness plan to a more comprehensive approach to emergency management. Communities, healthcare providers, and individuals/families all have been urged to take a more comprehensive look at their readiness for these types of events. Home healthcare organizations, including home health agencies, hospice providers, infusion providers, and medical equipment companies, can take a fresh and comprehensive look at their emergency management plan.

  20. The expanding universe of p53 targets.

    PubMed

    Menendez, Daniel; Inga, Alberto; Resnick, Michael A

    2009-10-01

    The p53 tumour suppressor is modified through mutation or changes in expression in most cancers, leading to the altered regulation of hundreds of genes that are directly influenced by this sequence-specific transcription factor. Central to the p53 master regulatory network are the target response element (RE) sequences. The extent of p53 transactivation and transcriptional repression is influenced by many factors, including p53 levels, cofactors and the specific RE sequences, all of which contribute to the role that p53 has in the aetiology of cancer. This Review describes the identification and functionality of REs and highlights the inclusion of non-canonical REs that expand the universe of genes and regulation mechanisms in the p53 tumour suppressor network.

  1. Expandable pallet for space station interface attachments

    NASA Technical Reports Server (NTRS)

    Wesselski, Clarence J. (Inventor)

    1989-01-01

    A foldable expandable pallet having a basic square configuration is disclosed. Each pallet is comprised of a plurality of struts, joined together by node point fittings to make a rigid structure. Some of the struts have hinge fittings and are spring loaded to permit collapse of the module for stowage and transport to a space station. Dimensions of the pallet are selected to provide convenient, closely spaced attachment points between the relatively widely spaced trusses of a space station platform. A pallet is attached to a truss at four points; one close fitting hole; two oversize holes; and a slot; to allow for thermal expansion/contraction and for manufacturing tolerances. Applications of the pallet include its use in rotary or angular joints; servicing of splints; with gridded plates; as an instrument mounting bases; and as a roadbed for a Mobile Service Center (MSC).

  2. Expandable pallet for space station interface attachments

    NASA Technical Reports Server (NTRS)

    Wesselski, Clarence J. (Inventor)

    1988-01-01

    Described is a foldable expandable pallet for Space Station interface attachments with a basic square configuration. Each pallet consists of a series of struts joined together by node point fittings to make a rigid structure. The struts have hinge fittings which are spring loaded to permit collapse of the module for stowage transport to a Space Station in the payload bay of the Space Shuttle, and development on orbit. Dimensions of the pallet are selected to provide convenient, closely spaced attachment points between the node points of the relatively widely spaced trusses of a Space Station platform. A pallet is attached to a strut at four points: one close fitting hole, two oversize holes, and a slot to allow for thermal expansion/contraction and for manufacturing tolerances. Applications of the pallet include its use in rotary or angular joints; servicing of splints; with gridded plates; as instrument mounting bases; and as a roadbed for a Mobile Service Center (MSC).

  3. Withdrawal: Expanding a Key Addiction Construct.

    PubMed

    Piper, Megan E

    2015-12-01

    Withdrawal is an essential component of classical addiction theory; it is a vital manifestation of dependence and motivates relapse. However, the traditional conceptualization of withdrawal as a cohesive collection of symptoms that emerge during drug deprivation and decline with either the passage of time or reinstatement of drug use, may be inadequate to explain scientific findings or fit with modern theories of addiction. This article expands the current understanding of tobacco withdrawal by examining: (1) withdrawal variability; (2) underlying causes of withdrawal variability, including biological and person factors, environmental influences, and the influence of highly routinized behavioral patterns; (3) new withdrawal symptoms that allow for enhanced characterization of the withdrawal experience; and (4) withdrawal-related cognitive processes. These topics provide guidance regarding the optimal assessment of withdrawal and illustrate the potential impact modern withdrawal conceptualization and assessment could have on identifying treatment targets.

  4. Expanding the role of the oncology nurse

    PubMed Central

    Quinn, A

    2008-01-01

    Oncology nursing continues to evolve in response to advances in cancer treatment, information and biotechnology. As new scientific and technological discoveries are integrated into cancer care, oncology nurses need to play a key role in the management of this patient population. The role of the oncology nurse has expanded significantly and can differ greatly across cultures. Sophisticated treatments and the growth of targeted therapies will create the challenge of ensuring that all nurses working in this arena are well-educated, independent thinkers. Thus the future success of oncology nurses will focus on enhancement of nursing practice through advanced education. The increased globalisation of healthcare offers exciting opportunities to accomplish this goal by allowing for collaborative relationships among oncology nurses across the globe. PMID:21611002

  5. Alice and Bob in an expanding spacetime

    NASA Astrophysics Data System (ADS)

    Alexander, Helder; de Souza, Gustavo; Mansfield, Paul; Sampaio, Marcos

    2015-09-01

    We investigate the teleportation of a qubit between two observers Alice and Bob in an asymptotically flat Robertson-Walker expanding spacetime. We use scalar or fermionic field modes inside Alice's and Bob's ideal cavities and show the degradation of the teleportation quality, as measured by the fidelity, through a mechanism governed by spacetime expansion. This reduction is demonstrated to increase with the rapidity of the expansion and to be highly sensitive to the coupling of the field to spacetime curvature, becoming considerably stronger as it reduces from conformal to minimal. We explore a perturbative approach in the cosmological parameters to compute the Bogoliubov coefficients in order to evaluate and compare the fidelity degradation of fermionic and scalar fields.

  6. Expandable slotted tubes offer well design benefits

    SciTech Connect

    Metcalfe, P.

    1996-10-01

    Multilateral wells can reduce well count by accessing multiple targets from one main overburden penetration. However, isolated laterals capable of handling increased production require a larger casing scheme than normal, along with whipstocks, plugs, gauges and downhole control valves. All this equipment is difficult to include in a slimhole or monobore multilateral well design. In many instances slimhole technology and multilateral designs are not compatible. Expanded slotted tubing (EST) technology was designed to complement multilateral and slimhole monobore applications as well as conventional wells. The paper describes the concept, alternative borehole liner, downhole forces, a case history from a southwestern Texas field, objectives, formation pressure testing, EST running and cementing, EST expansion, drill-out, log and pressure test, and EST as a completion liner for multilateral wells.

  7. The law's interface with expanding technology

    NASA Technical Reports Server (NTRS)

    Green, H. P.

    1972-01-01

    The role of the law in technology assessment is described in generalized terms of a legal system as it confronts expanding technology. The functions of a technology assessment are considered to be twofold; provide for legislative action designed to channel technological advance along lines which are regarded as optimal from the standpoint of society's interests; and encourage and promote legislative action which will deal decisively with the potential disruptions and injuries caused by technology at a much earlier stage of the growth of the technology than is feasible under the present legal system. It is concluded that since new law always has a disruptive effect on expectations and commitments arrived at under old law, it is generally desirable that new legislation should make the least possible change in the law consistant with accomplishing the desired objective.

  8. NOVAE EJECTA AS DISCRETE ADIABATICALLY EXPANDING GLOBULES

    SciTech Connect

    Williams, Robert

    2013-09-15

    Available data for novae show that the X-ray and visible spectral regions correlate with each other as they evolve. Large differences in ionization exist simultaneously in the two wavelength regimes, and a straightforward model is proposed that explains the characteristics observed in both spectral regimes. Its key features are (1) ejected blobs of very high density gas from the white dwarf (WD) that expand to create within each clump a wide range of emitting density, ionization, and velocity, and (2) a more homogeneous circumbinary envelope of gas that is produced by secondary star mass loss. The relative mass loss rates from the two stars determine whether the He/N or the Fe II visible spectrum predominates during decline, when hard X-rays are detected, and when the WD can be detected as a super soft X-ray source.

  9. Expanding forensic science through forensic intelligence.

    PubMed

    Ribaux, Olivier; Talbot Wright, Benjamin

    2014-12-01

    Research and Development ('R&D') in forensic science currently focuses on innovative technologies improving the efficiency of existing forensic processes, from the detection of marks and traces at the scene, to their presentation in Court. R&D approached from this perspective provides no response to doubts raised by recent criminological studies, which question the effective contribution of forensic science to crime reduction, and to policing in general. Traces (i.e. forensic case data), as remnants of criminal activity are collected and used in various forms of crime monitoring and investigation. The aforementioned doubts therefore need to be addressed by expressing how information is conveyed by traces in these processes. Modelling from this standpoint expands the scope of forensic science and provides new R&D opportunities. Twelve propositions for R&D are stated in order to pave the way. PMID:25498939

  10. Gravitational wave memory in an expanding universe

    NASA Astrophysics Data System (ADS)

    Tolish, Alexander; Wald, Robert

    2016-03-01

    We investigate the gravitational wave memory effect in an expanding FLRW spacetime. We find that if the gravitational field is decomposed into gauge-invariant scalar, vector, and tensor modes after the fashion of Bardeen, only the tensor mode gives rise to memory, and this memory can be calculated using the retarded Green's function associated with the tensor wave equation. If locally similar radiation source events occur on flat and FLRW backgrounds, we find that the resulting memories will differ only by a redshift factor, and we explore whether or not this factor depends on the expansion history of the FLRW universe. We compare our results to related work by Bieri, Garfinkle, and Yau.

  11. Study of an expanding magnetic cloud

    NASA Astrophysics Data System (ADS)

    Nakwacki, M. S.; Dasso, S.; Mandrini, C. H.; Démoulin, P.

    Magnetic Clouds (MCs) transport into the interplanetary medium the magnetic flux and helicity released in coronal mass ejections by the Sun. At 1 AU from the Sun, MCs are generally modelled as static flux ropes. However, the velocity profile of some MCs presents signatures of expansion. We analise here the magnetic structure of an expanding magnetic cloud observed by Wind spacecraft. We consider a dynamical model, based on a self-similar behaviour for the cloud radial velocity. We assume a free expansion for the cloud, and a cylindrical linear force free field (i.e., the Lundquist's field) as the initial condition for its magnetic configuration. We derive theoretical expressions for the magnetic flux across a surface perpendicular to the cloud axis, for the magnetic helicity and magnetic energy per unit length along the tube using the self-similar model. Finally, we compute these magntitudes with the fitted parameters. FULL TEXT IN SPANISH

  12. High temperature expanding cement composition and use

    DOEpatents

    Nelson, Erik B.; Eilers, Louis H.

    1982-01-01

    A hydratable cement composition useful for preparing a pectolite-containing expanding cement at temperatures above about 150.degree. C. comprising a water soluble sodium salt of a weak acid, a 0.1 molar aqueous solution of which salt has a pH of between about 7.5 and about 11.5, a calcium source, and a silicon source, where the atomic ratio of sodium to calcium to silicon ranges from about 0.3:0.6:1 to about 0.03:1:1; aqueous slurries prepared therefrom and the use of such slurries for plugging subterranean cavities at a temperature of at least about 150.degree. C. The invention composition is useful for preparing a pectolite-containing expansive cement having about 0.2 to about 2 percent expansion, by volume, when cured at at least 150.degree. C.

  13. Novae Ejecta as Discrete Adiabatically Expanding Globules

    NASA Astrophysics Data System (ADS)

    Williams, Robert

    2013-09-01

    Available data for novae show that the X-ray and visible spectral regions correlate with each other as they evolve. Large differences in ionization exist simultaneously in the two wavelength regimes, and a straightforward model is proposed that explains the characteristics observed in both spectral regimes. Its key features are (1) ejected blobs of very high density gas from the white dwarf (WD) that expand to create within each clump a wide range of emitting density, ionization, and velocity, and (2) a more homogeneous circumbinary envelope of gas that is produced by secondary star mass loss. The relative mass loss rates from the two stars determine whether the He/N or the Fe II visible spectrum predominates during decline, when hard X-rays are detected, and when the WD can be detected as a super soft X-ray source.

  14. Expanding the role of the oncology nurse.

    PubMed

    Quinn, A

    2008-07-01

    Oncology nursing continues to evolve in response to advances in cancer treatment, information and biotechnology. As new scientific and technological discoveries are integrated into cancer care, oncology nurses need to play a key role in the management of this patient population. The role of the oncology nurse has expanded significantly and can differ greatly across cultures. Sophisticated treatments and the growth of targeted therapies will create the challenge of ensuring that all nurses working in this arena are well-educated, independent thinkers. Thus the future success of oncology nurses will focus on enhancement of nursing practice through advanced education. The increased globalisation of healthcare offers exciting opportunities to accomplish this goal by allowing for collaborative relationships among oncology nurses across the globe.

  15. Expanding forensic science through forensic intelligence.

    PubMed

    Ribaux, Olivier; Talbot Wright, Benjamin

    2014-12-01

    Research and Development ('R&D') in forensic science currently focuses on innovative technologies improving the efficiency of existing forensic processes, from the detection of marks and traces at the scene, to their presentation in Court. R&D approached from this perspective provides no response to doubts raised by recent criminological studies, which question the effective contribution of forensic science to crime reduction, and to policing in general. Traces (i.e. forensic case data), as remnants of criminal activity are collected and used in various forms of crime monitoring and investigation. The aforementioned doubts therefore need to be addressed by expressing how information is conveyed by traces in these processes. Modelling from this standpoint expands the scope of forensic science and provides new R&D opportunities. Twelve propositions for R&D are stated in order to pave the way.

  16. Expanding roles for GILT in immunity

    PubMed Central

    West, Laura Ciaccia

    2015-01-01

    Gamma-interferon-inducible lysosomal thiol reductase (GILT), a thioredoxin-related oxidoreductase, functions in MHC class II-restricted antigen processing and MHC class I-restricted cross-presentation by reducing disulfide bonds of endocytosed proteins and facilitating their unfolding and optimal degradation. However, recent reports have greatly expanded our understanding of GILT’s function. Several studies of GILT and antigen processing have shown that the influence of GILT on the peptide repertoire can alter the character of the immune response and affect central tolerance. Furthermore, a few unexpected roles for GILT have been uncovered: as a host factor for Listeria monocytogenes infection, in the maintenance of cellular glutathione levels (GSH), and possibly outside the cell, as enzymatically active GILT is secreted by activated macrophages. PMID:23246037

  17. Withdrawal: Expanding a Key Addiction Construct.

    PubMed

    Piper, Megan E

    2015-12-01

    Withdrawal is an essential component of classical addiction theory; it is a vital manifestation of dependence and motivates relapse. However, the traditional conceptualization of withdrawal as a cohesive collection of symptoms that emerge during drug deprivation and decline with either the passage of time or reinstatement of drug use, may be inadequate to explain scientific findings or fit with modern theories of addiction. This article expands the current understanding of tobacco withdrawal by examining: (1) withdrawal variability; (2) underlying causes of withdrawal variability, including biological and person factors, environmental influences, and the influence of highly routinized behavioral patterns; (3) new withdrawal symptoms that allow for enhanced characterization of the withdrawal experience; and (4) withdrawal-related cognitive processes. These topics provide guidance regarding the optimal assessment of withdrawal and illustrate the potential impact modern withdrawal conceptualization and assessment could have on identifying treatment targets. PMID:25744958

  18. Expandable and reconfigurable instrument node arrays

    NASA Technical Reports Server (NTRS)

    Hilliard, Lawrence M. (Inventor); Deshpande, Manohar (Inventor)

    2012-01-01

    An expandable and reconfigurable instrument node includes a feature detection means and a data processing portion in communication with the feature detection means, the data processing portion configured and disposed to process feature information. The instrument node further includes a phase locked loop (PLL) oscillator in communication with the data processing portion, the PLL oscillator configured and disposed to provide PLL information to the processing portion. The instrument node further includes a single tone transceiver and a pulse transceiver in communication with the PLL oscillator, the single tone transceiver configured and disposed to transmit or receive a single tone for phase correction of the PLL oscillator and the pulse transceiver configured and disposed to transmit and receive signals for phase correction of the PLL oscillator. The instrument node further includes a global positioning (GPA) receiver in communication with the processing portion, the GPS receiver configured and disposed to establish a global position of the instrument node.

  19. Henry Norris Russell and the Expanding Universe

    NASA Astrophysics Data System (ADS)

    DeVorkin, D.

    2013-04-01

    Henry Norris Russell, one of the most influential American astronomers of the first half of the 20th Century, had a special place in his heart for the Lowell Observatory. Although privately critical of the founder for his pronouncements about life on Mars and the superiority of the Mars Hill observing site, he always supported the Observatory in public and professional circles. He staunchly supported Tombaugh's detection of a planet as leading from Lowell's prediction, and always promoted V. M. Slipher's spectroscopic investigations of planetary and stellar phenomena. But how did he react to Slipher's puzzling detection of the extreme radial velocities of spiral nebulae starting in 1912, and how did he regard the extension and interpretation of those observations by Hubble and others in following decades? Here we describe the arc of Russell's reactions, dating from Slipher's first detection, as an indicator of how mainstream stellar astronomers reacted to the concept of an expanding universe.

  20. Financing Expanded Learning Time in Schools: A Look at Five District-Expanded Time Schools

    ERIC Educational Resources Information Center

    Kaplan, Claire; Farbman, David A.; Deich, Sharon; Padgette, Heather Clapp

    2014-01-01

    Over the last several years, public education in the U.S. has experienced a remarkable growth in the number of schools that have expanded their schedules beyond the conventional calendar of 180 6.5-hour days. Spurred by significant policy activity at the federal, state, and local levels, more and more educators have capitalized on opportunities to…

  1. BOOK REVIEW: The Artful Universe Expanded

    NASA Astrophysics Data System (ADS)

    Bassett, B. A.

    2005-07-01

    The cosmos is an awfully big place and there is no better guide to its vast expanse and fascinating nooks and crannies than John Barrow. A professor of mathematical sciences at Cambridge University, Barrow embodies that rare combination of highly polished writer and expert scientist. His deft touch brings together the disparate threads of human knowledge and weaves them into a tapestry as rich and interesting for the expert as it is for the layperson. The Artful Universe Expanded is an updated edition of this popular book first published in 1995. It explores the deeply profound manner in which natural law and the nature of the cosmos have moulded and shaped us, our cultures and the very form of our arts and music—a new type of `cosmic' anthropology. The main themes Barrow chooses for revealing this new anthropology are the subjects of evolution, the size of things, the heavens and the nature of music. The book is a large, eclectic repository of knowledge often unavailable to the layperson,\\endcolumn hidden in esoteric libraries around the world. It rivals The Da Vinci Code for entertainment value and insights, but this time it is Nature’s code that is revealed. It is rare indeed to find common threads drawn through topics as diverse as The Beetles, Bach and Beethoven or between Jackson Pollock, the Aztecs, Kant, Picasso, Byzantine mosaics, uranium-235 and the helix nebula. Barrow unerringly binds them together, presenting them in a stimulating, conversational style that belies the amount of time that must have gone into researching this book. Dip into it at random, or read it from cover to cover, but do read it. The Artful Universe Expanded is an entertaining antidote to the oft-lamented pressures to know more and more about less and less and the apparently inexorable march of specialization. On reading this book one can, for a short time at least, hold in one’s mind a vision that unifies science, art and culture and glimpse a universal tapestry of great

  2. Transparency parameters from relativistically expanding outflows

    SciTech Connect

    Bégué, D.; Iyyani, S.

    2014-09-01

    In many gamma-ray bursts a distinct blackbody spectral component is present, which is attributed to the emission from the photosphere of a relativistically expanding plasma. The properties of this component (temperature and flux) can be linked to the properties of the outflow and have been presented in the case where there is no sub-photospheric dissipation and the photosphere is in coasting phase. First, we present the derivation of the properties of the outflow for finite winds, including when the photosphere is in the accelerating phase. Second, we study the effect of localized sub-photospheric dissipation on the estimation of the parameters. Finally, we apply our results to GRB 090902B. We find that during the first epoch of this burst the photosphere is most likely to be in the accelerating phase, leading to smaller values of the Lorentz factor than the ones previously estimated. For the second epoch, we find that the photosphere is likely to be in the coasting phase.

  3. Expanding Taylor bubble under constant heat flux

    NASA Astrophysics Data System (ADS)

    Voirand, Antoine; Benselama, Adel M.; Ayel, Vincent; Bertin, Yves

    2016-09-01

    Modelization of non-isothermal bubbles expanding in a capillary, as a contribution to the understanding of the physical phenomena taking place in Pulsating Heat Pipes (PHPs), is the scope of this paper. The liquid film problem is simplified and solved, while the thermal problem takes into account a constant heat flux density applied at the capillary tube wall, exchanging with the liquid film surrounding the bubble and also with the capillary tube outside medium. The liquid slug dynamics is solved using the Lucas-Washburn equation. Mass and energy balance on the vapor phase allow governing equations of bubble expansion to be written. The liquid and vapor phases are coupled only through the saturation temperature associated with the vapor pressure, assumed to be uniform throughout the bubble. Results show an over-heating of the vapor phase, although the particular thermal boundary condition used here always ensures an evaporative mass flux at the liquid-vapor interface. Global heat exchange is also investigated, showing a strong decreasing of the PHP performance to convey heat by phase change means for large meniscus velocities.

  4. Branching instability in expanding bacterial colonies

    PubMed Central

    Giverso, Chiara; Verani, Marco; Ciarletta, Pasquale

    2015-01-01

    Self-organization in developing living organisms relies on the capability of cells to duplicate and perform a collective motion inside the surrounding environment. Chemical and mechanical interactions coordinate such a cooperative behaviour, driving the dynamical evolution of the macroscopic system. In this work, we perform an analytical and computational analysis to study pattern formation during the spreading of an initially circular bacterial colony on a Petri dish. The continuous mathematical model addresses the growth and the chemotactic migration of the living monolayer, together with the diffusion and consumption of nutrients in the agar. The governing equations contain four dimensionless parameters, accounting for the interplay among the chemotactic response, the bacteria–substrate interaction and the experimental geometry. The spreading colony is found to be always linearly unstable to perturbations of the interface, whereas branching instability arises in finite-element numerical simulations. The typical length scales of such fingers, which align in the radial direction and later undergo further branching, are controlled by the size parameters of the problem, whereas the emergence of branching is favoured if the diffusion is dominant on the chemotaxis. The model is able to predict the experimental morphologies, confirming that compact (resp. branched) patterns arise for fast (resp. slow) expanding colonies. Such results, while providing new insights into pattern selection in bacterial colonies, may finally have important applications for designing controlled patterns. PMID:25652464

  5. Microstructural analysis of Iberian expanded clay aggregates.

    PubMed

    Bogas, J Alexandre; Mauricio, António; Pereira, M F C

    2012-10-01

    This article presents a detailed study of the microstructure of Iberian expanded clay lightweight aggregates (LWA). Other than more commonly used mercury porosimetry (MP) and water absorption methods, the experimental study involves optical microscopy, scanning electron microscopy (SEM), and microtomography (μ-CT). Pore connectivity and how it is deployed are shown to some degree, and the pore size spectrum is estimated. LWA are in general characterized by a dense outer shell up to 200 μm thick, encasing an inner cellular structure of 10-100 times bigger pore size. Aggregate pore sizes may span from some hundreds of nanometers up to over 1 mm, though the range of 1-25 μm is more typical. A noteworthy fraction of these pores is closed, and they are mainly up to 1 μm. It is also shown that macropore spatial arrangement is affected by the manufacturing process. A step forward is given to understanding how the outer shell and the inner pore network influence the mechanical and physical LWA properties, particularly the density and water absorption. The joint consideration of μ-CT and SEM seems to be the most appropriate methodology to study LWA microstructure. MP analysis is likely to distort LWA pore spectrum assessment. PMID:23031601

  6. The expanding universe of noncoding RNAs.

    PubMed

    Hannon, G J; Rivas, F V; Murchison, E P; Steitz, J A

    2006-01-01

    The 71st Cold Spring Harbor Symposium on Quantitative Biology celebrated the numerous and expanding roles of regulatory RNAs in systems ranging from bacteria to mammals. It was clearly evident that noncoding RNAs are undergoing a renaissance, with reports of their involvement in nearly every cellular process. Previously known classes of longer noncoding RNAs were shown to function by every possible means-acting catalytically, sensing physiological states through adoption of complex secondary and tertiary structures, or using their primary sequences for recognition of target sites. The many recently discovered classes of small noncoding RNAs, generally less than 35 nucleotides in length, most often exert their effects by guiding regulatory complexes to targets via base-pairing. With the ability to analyze the RNA products of the genome in ever greater depth, it has become clear that the universe of noncoding RNAs may extend far beyond the boundaries we had previously imagined. Thus, as much as the Symposium highlighted exciting progress in the field, it also revealed how much farther we must go to understand fully the biological impact of noncoding RNAs.

  7. The expanding universe of prion diseases.

    PubMed

    Watts, Joel C; Balachandran, Aru; Westaway, David

    2006-03-01

    Prions cause fatal and transmissible neurodegenerative disease. These etiological infectious agents are formed in greater part from a misfolded cell-surface protein called PrP(C). Several mammalian species are affected by the diseases, and in the case of "mad cow disease" (BSE) the agent has a tropism for humans, with negative consequences for agribusiness and public health. Unfortunately, the known universe of prion diseases is expanding. At least four novel prion diseases--including human diseases variant Creutzfeldt-Jakob disease (vCJD) and sporadic fatal insomnia (sFI), bovine amyloidotic spongiform encephalopathy (BASE), and Nor98 of sheep--have been identified in the last ten years, and chronic wasting disease (CWD) of North American deer (Odocoileus Specis) and Rocky Mountain elk (Cervus elaphus nelsoni) is undergoing a dramatic spread across North America. While amplification (BSE) and dissemination (CWD, commercial sourcing of cervids from the wild and movement of farmed elk) can be attributed to human activity, the origins of emergent prion diseases cannot always be laid at the door of humankind. Instead, the continued appearance of new outbreaks in the form of "sporadic" disease may be an inevitable outcome in a situation where the replicating pathogen is host-encoded.

  8. Tachyonic resonance preheating in an expanding universe

    SciTech Connect

    Abolhasani, Ali Akbar; Firouzjahi, Hassan; Sheikh-Jabbari, M. M.

    2010-02-15

    In this paper the tachyonic resonance preheating generated from the bosonic trilinear {phi}{chi}{sup 2} interactions in an expanding universe is studied. In {lambda}{phi}{sup 4}/4 inflationary model the trilinear interaction, in contrast to the four-legs {phi}{sup 2{chi}2}, breaks the conformal symmetry explicitly and the resonant source term becomes nonperiodic, making the Floquet theorem inapplicable. We find that the occupation number of the produced {chi} particles has a nonlinear exponential growth with exponent {approx}x{sup 3/2}, where x is the conformal time. This should be contrasted with preheating from a periodic resonant source arising, for example, from the four-legs {phi}{sup 2{chi}2} interaction, where the occupation number has a linear exponential growth. We present an analytic method to compute the interference term coming from phases accumulated in nontachyonic scattering regions and show that the effects of the interference term cause ripples on x{sup 3/2} curve, a result which is confirmed by numerical analysis. Studying the effects of backreaction of the {chi} particles, we show that tachyonic resonance preheating in our model can last long enough to transfer most of the energy from the background inflation field {phi}, providing an efficient model for preheating in the chaotic inflation models.

  9. The Hubble Constant and the Expanding Universe

    NASA Astrophysics Data System (ADS)

    Freedman, Wendy

    2003-01-01

    In 1929 Edwin Hubble proved that our universe is expanding by showing that the farther a galaxy is from us, the faster it is speeding away into space. This velocity-distance relation came to be called Hubble's law, and the value that describes the rate of expansion is known as the Hubble constant, or H0 . Like the speed of light, H0 is a fundamental constant, and it is a key parameter needed to estimate both the age and size of the universe. Since the late 1950s astronomers have been arguing for an H0 value between 50 to 100 kilometers per second per megaparsec, a lack of precision that produced an unacceptably wide range of ages for the universe—anywhere from 10 to 20 billion years. Using the Hubble Space Telescope, Freedman and her colleagues measured H0 to an unprecedented level of accuracy, deriving a value of 72, with an uncertainty of 10 percent—a milestone achievement in cosmology. The new result suggests that our universe is about 13 billion years old, give or take a billion years, and it's a value that sits comfortably alongside the 12 billion years estimated for the age of the oldest stars.

  10. The expanding universe of prion diseases.

    PubMed

    Watts, Joel C; Balachandran, Aru; Westaway, David

    2006-03-01

    Prions cause fatal and transmissible neurodegenerative disease. These etiological infectious agents are formed in greater part from a misfolded cell-surface protein called PrP(C). Several mammalian species are affected by the diseases, and in the case of "mad cow disease" (BSE) the agent has a tropism for humans, with negative consequences for agribusiness and public health. Unfortunately, the known universe of prion diseases is expanding. At least four novel prion diseases--including human diseases variant Creutzfeldt-Jakob disease (vCJD) and sporadic fatal insomnia (sFI), bovine amyloidotic spongiform encephalopathy (BASE), and Nor98 of sheep--have been identified in the last ten years, and chronic wasting disease (CWD) of North American deer (Odocoileus Specis) and Rocky Mountain elk (Cervus elaphus nelsoni) is undergoing a dramatic spread across North America. While amplification (BSE) and dissemination (CWD, commercial sourcing of cervids from the wild and movement of farmed elk) can be attributed to human activity, the origins of emergent prion diseases cannot always be laid at the door of humankind. Instead, the continued appearance of new outbreaks in the form of "sporadic" disease may be an inevitable outcome in a situation where the replicating pathogen is host-encoded. PMID:16609731

  11. The expanding fireball of Nova Delphini 2013.

    PubMed

    Schaefer, G H; ten Brummelaar, T; Gies, D R; Farrington, C D; Kloppenborg, B; Chesneau, O; Monnier, J D; Ridgway, S T; Scott, N; Tallon-Bosc, I; McAlister, H A; Boyajian, T; Maestro, V; Mourard, D; Meilland, A; Nardetto, N; Stee, P; Sturmann, J; Vargas, N; Baron, F; Ireland, M; Baines, E K; Che, X; Jones, J; Richardson, N D; Roettenbacher, R M; Sturmann, L; Turner, N H; Tuthill, P; van Belle, G; von Braun, K; Zavala, R T; Banerjee, D P K; Ashok, N M; Joshi, V; Becker, J; Muirhead, P S

    2014-11-13

    A classical nova occurs when material accreting onto the surface of a white dwarf in a close binary system ignites in a thermonuclear runaway. Complex structures observed in the ejecta at late stages could result from interactions with the companion during the common-envelope phase. Alternatively, the explosion could be intrinsically bipolar, resulting from a localized ignition on the surface of the white dwarf or as a consequence of rotational distortion. Studying the structure of novae during the earliest phases is challenging because of the high spatial resolution needed to measure their small sizes. Here we report near-infrared interferometric measurements of the angular size of Nova Delphini 2013, starting one day after the explosion and continuing with extensive time coverage during the first 43 days. Changes in the apparent expansion rate can be explained by an explosion model consisting of an optically thick core surrounded by a diffuse envelope. The optical depth of the ejected material changes as it expands. We detect an ellipticity in the light distribution, suggesting a prolate or bipolar structure that develops as early as the second day. Combining the angular expansion rate with radial velocity measurements, we derive a geometric distance to the nova of 4.54 ± 0.59 kiloparsecs from the Sun. PMID:25363778

  12. Homogeneous cosmology with aggressively expanding civilizations

    NASA Astrophysics Data System (ADS)

    Olson, S. Jay

    2015-11-01

    In the context of a homogeneous Universe, we note that the appearance of aggressively expanding advanced life is geometrically similar to the process of nucleation and bubble growth in a first-order cosmological phase transition. We exploit this similarity to describe the dynamics of life saturating the Universe on a cosmic scale, adapting the phase transition model to incorporate probability distributions of expansion and resource consumption strategies. Through a series of numerical solutions spanning several orders of magnitude in the input assumption parameters, the resulting cosmological model is used to address basic questions related to the intergalactic spreading of life, dealing with issues such as timescales, observability, competition between strategies, and first-mover advantage. Finally, we examine physical effects on the Universe itself, such as reheating and the backreaction on the evolution of the scale factor, if such life is able to control and convert a significant fraction of the available pressureless matter into radiation. We conclude that the existence of life, if certain advanced technologies are practical, could have a significant influence on the future large-scale evolution of the Universe.

  13. Gene family matters: expanding the HGNC resource.

    PubMed

    Daugherty, Louise C; Seal, Ruth L; Wright, Mathew W; Bruford, Elspeth A

    2012-01-01

    The HUGO Gene Nomenclature Committee (HGNC) assigns approved gene symbols to human loci. There are currently over 33,000 approved gene symbols, the majority of which represent protein-coding genes, but we also name other locus types such as non-coding RNAs, pseudogenes and phenotypic loci. Where relevant, the HGNC organise these genes into gene families and groups. The HGNC website http://www.genenames.org/ is an online repository of HGNC-approved gene nomenclature and associated resources for human genes, and includes links to genomic, proteomic and phenotypic information. In addition to this, we also have dedicated gene family web pages and are currently expanding and generating more of these pages using data curated by the HGNC and from information derived from external resources that focus on particular gene families. Here, we review our current online resources with a particular focus on our gene family data, using it to highlight our new Gene Symbol Report and gene family data downloads. PMID:23245209

  14. Is Space Really Expanding? A Counterexample

    NASA Astrophysics Data System (ADS)

    Chodorowski, Michał J.

    2007-03-01

    In all Friedman models, the cosmological redshift is widely interpreted as a consequence of the general-relativistic phenomenon of expansion of space. Other commonly believed consequences of this phenomenon are superluminal recession velocities of distant galaxies, and the distance to the particle horizon greater than ct (where t is the age of the Universe), in apparent conflict with special relativity. Here, we study a particular Friedman model: empty universe. This model exhibits both cosmological redshift, superluminal velocities and infinite distance to the horizon. However, we show that the cosmological redshift is there simply a relativistic Doppler shift. Moreover, apparently superluminal velocities and ‘acausal’ distance to the horizon are in fact a direct consequence of special-relativistic phenomenon of time dilation, as well as of the adopted definition of distance in cosmology. There is no conflict with special relativity, whatsoever. In particular, inertial recession velocities are subluminal. Since in the real Universe, sufficiently distant galaxies recede with relativistic velocities, these special-relativistic effects must be at least partly responsible for the cosmological redshift and the aforementioned ‘superluminalities’, commonly attributed to the expansion of space. Let us finish with a question resembling a Buddhism-Zen ‘koan’: in an empty universe, what is expanding?

  15. Erotized transference reconsidered: expanding the countertransference dimension.

    PubMed

    Eber, M

    1990-01-01

    A reconsideration of the erotized transference from a contemporary perspective has been presented utilizing detailed case material provided by Stoller. The main thesis is that this type of transference, traditionally conceived as a product of a particular kind of patient often felt to be borderline, is better understood as arising in a specific intersubjective context involving both participants in the psychoanalytic situation. The focus is on the intricate interaction of analyst and patient, recognizing that either may serve as a selfobject for the other. This view assumes a more expanded countertransference role than recognized in the earlier literature. The psychoanalytic situation can be erotized by either or both participants. A corollary thesis is that the details of a patient's fantasy should also be viewed as codetermined and that imbedded within it might be the patient's subjective experience of the psychoanalytic interaction. Alluded to peripherally is that the erotized transference in the interaction between male analyst and female patient is, in part, a manifestation of traditional roles assumed in situations involving a male authority figure in close engagement with a female who perceives herself as relatively powerless. This issue has recently received considerable attention from writers who have addressed themselves to the important gender issues in psychoanalysis.

  16. Expanding the role of internal facility assessments

    SciTech Connect

    Kolpa, R.L.; Levenson, J.B.; Weaver, M.A.

    1996-05-01

    The US Air Force (USAF) Environmental Compliance Assessment and Management Program (ECAMP) is an effective and comprehensive system to evaluate environmental compliance at individual USAF installations. The ECAMP assessment is typically performed by a team of experts from the installation`s Major Command (MAJCOM) Headquarters, and is often augmented with technical contractor support. As directed by Air Force policy, an external ECAMP assessment is required at a minimum of every three years for each installation. In the intervening years, each installation is required to perform an internal ECAMP assessment, with its own personnel and resources. Even though team composition differs, the internal and external ECAMP assessments are likely to be very similar in scope, objectives, and deliverables. For over nine years, Argonne National Laboratory (ANL) has supported several Air Force MAJCOMs in performing their external ECAMP assessments. More recently, ANL has also had the opportunity to provide technical support and training at individual installations during their preparation and conduct of internal ECAMP assessments. From that experience, the authors have learned that the quality and value of the internal assessment is enhanced by making it a vehicle for training, planning, and interaction among organizations. Various strategies and techniques have been successfully employed to derive maximum benefit and insight from the internal assessment process. Experiences that involve expanding the scope and objectives of internal assessments to meet specific goals are presented. The expansion of scope and objectives include preassessment training, planning, and evaluator interactions as part of the overall internal assessment process.

  17. Expandable Purge Chambers Would Protect Cryogenic Fittings

    NASA Technical Reports Server (NTRS)

    Townsend, Ivan I., III

    2004-01-01

    Expandable ice-prevention and cleanliness-preservation (EIP-CP) chambers have been proposed to prevent the accumulation of ice or airborne particles on quick-disconnect (QD) fittings, or on ducts or tubes that contain cryogenic fluids. In the original application for which the EIP-CP chambers were conceived, there is a requirement to be able to disconnect and reconnect the QD fittings in rapid succession. If ice were to form on the fittings by condensation and freezing of airborne water vapor on the cold fitting surfaces, the ice could interfere with proper mating of the fittings, making it necessary to wait an unacceptably long time for the ice to thaw before attempting reconnection. By keeping water vapor away from the cold fitting surfaces, the EIP-CP chambers would prevent accumulation of ice, preserving the ability to reconnect as soon as required. Basically, the role of an EIP-CP chamber would be to serve as an enclosure for a flow of dry nitrogen gas that would keep ambient air away from QD cryogenic fittings. An EIP-CP chamber would be an inflatable device made of a fabriclike material. The chamber would be attached to an umbilical plate holding a cryogenic QD fitting.

  18. Helical Screw Expander Evaluation Project. Final report

    SciTech Connect

    McKay, R.

    1982-03-01

    A functional 1-MW geothermal electric power plant that featured a helical screw expander was produced and then tested in Utah in 1978 to 1979 with a demonstrated average performance of approximately 45% machine efficiency over a wide range of test conditions in noncondensing operation on two-phase geothermal fluids. The Project also produced a computer-equipped data system, an instrumentation and control van, and a 1000-kW variable load bank, all integrated into a test array designed for operation at a variety of remote test sites. Additional testing was performed in Mexico in 1980 under a cooperative test program using the same test array, and machine efficiency was measured at 62% maximum with the rotors partially coated with scale, compared with approximately 54% maximum in Utah with uncoated rotors, confirming the importance of scale deposits within the machine on performance. Data are presented for the Utah testing and for the noncondensing phases of the testing in Mexico. Test time logged was 437 hours during the Utah tests and 1101 hours during the Mexico tests.

  19. Autoimmune thyroid disease: an expanding spectrum.

    PubMed

    Fisher, D A; Pandian, M R; Carlton, E

    1987-08-01

    Autoimmune thyroid disease classically has included Hashimoto's thyroiditis and Graves' disease. Hashimoto's thyroiditis probably also includes focal thyroiditis, fibrous thyroiditis, primary myxedema, and Hashitoxicosis as variants. Graves' disease is associated with ophthalmopathy and dermopathy, and recent evidence suggests that these manifestations are autoimmune phenomena as well. Other associated autoimmune disorders include idiopathic thrombocytopenic purpura and antigen-antibody complex nephritis. Nonthyroid endocrine autoimmune deficiency disorders also have been classified as part of the spectrum of thyroid autoimmune disease. With the recent recognition of the spectrum of autoimmune mechanisms and antibody types and methods to distinguish antibody functions or types, our understanding of postpartum and neonatal thyroid disorders has been advanced considerably. The spectrum of neonatal thyroid disorders in the infants of women with autoimmune disease relates to the levels and types of antithyroid antibodies acquired from the mother. Finally, there is suggestive evidence that nonspecific goiter, including simple adolescent goiter and multinodular goiter as well as some cases of sporadic cretinism, may be part of an even more expanded spectrum of autoimmune thyroid disease.

  20. Expanded polylactide bead foaming - A new technology

    NASA Astrophysics Data System (ADS)

    Nofar, M.; Ameli, A.; Park, C. B.

    2015-05-01

    Bead foaming technology with double crystal melting peak structure has been recognized as a promising method to produce low-density foams with complex geometries. During the molding stage of the bead foams, the double peak structure generates a strong bead-to-bead sintering and maintains the overall foam structure. During recent years, polylactide (PLA) bead foaming has been of the great interest of researchers due to its origin from renewable resources and biodegradability. However, due to the PLA's low melt strength and slow crystallization kinetics, the attempts have been limited to the manufacturing methods used for expanded polystyrene. In this study, for the first time, we developed microcellular PLA bead foams with double crystal melting peak structure. Microcellular PLA bead foams were produced with expansion ratios and average cell sizes ranging from 3 to 30-times and 350 nm to 15 µm, respectively. The generated high melting temperature crystals during the saturation significantly affected the expansion ratio and cell density of the PLA bead foams by enhancing the PLA's poor melt strength and promoting heterogeneous cell nucleation around the crystals.

  1. Tabbed Tissue Expanders Improve Breast Symmetry Scores in Breast Reconstruction

    PubMed Central

    Khavanin, Nima; Gust, Madeleine J; Grant, David W; Nguyen, Khang T

    2014-01-01

    Background Achieving symmetry is a key goal in breast reconstruction. Anatomically shaped tabbed expanders are a new tool in the armamentarium of the breast reconstruction surgeon. Suture tabs allow for full control over the expander position and thus inframammary fold position, and, in theory, tabbed expanders mitigate many factors responsible for poor symmetry. The impact of a tabbed expander on breast symmetry, however, has not been formally reported. This study aims to evaluate breast symmetry following expander-implant reconstruction using tabbed and non-tabbed tissue expanders. Methods A chart review was performed of 188 consecutive expander-implant reconstructions that met the inclusion criteria of adequate follow-up data and postoperative photographs. Demographic, oncologic, postoperative complication, and photographic data was obtained for each patient. The photographic data was scored using a 4-point scale assessing breast symmetry by three blinded, independent reviewers. Results Of the 188 patients, 74 underwent reconstruction with tabbed expanders and 114 with non-tabbed expanders. The tabbed cohort had significantly higher symmetry scores than the non-tabbed cohort (2.82/4±0.86 vs. 2.55/4±0.92, P=0.034). Conclusions The use of tabbed tissue expanders improves breast symmetry in tissue expander-implant-based breast reconstruction. Fixation of the expander to the chest wall allows for more precise control over its location and counteracts the day-to-day translational forces that may influence the shape and location of the expander pocket, mitigating many factors responsible for breast asymmetry. PMID:24511496

  2. Spherical Accretion in a Uniformly Expanding Universe

    NASA Astrophysics Data System (ADS)

    Colpi, Monica; Shapiro, Stuart L.; Wasserman, Ira

    1996-10-01

    We consider spherically symmetric accretion of material from an initially homogeneous, uniformly expanding medium onto a Newtonian point mass M. The gas is assumed to evolve adiabatically with a constant adiabatic index F, which we vary over the range Γ ɛ [1, 5/3]. We use a one-dimensional Lagrangian code to follow the spherical infall of material as a function of time. Outflowing shells gravitationally bound to the point mass fall back, giving rise to a inflow rate that, after a rapid rise, declines as a power law in time. If there were no outflow initially, Bondi accretion would result, with a characteristic accretion time-scale ta,0. For gas initially expanding at a uniform rate, with a radial velocity U = R/t0 at radius R, the behavior of the flow at all subsequent times is determined by ta,0/t0. If ta,0/t0 ≫ 1, the gas has no time to respond to pressure forces, so the fluid motion is nearly collisionless. In this case, only loosely bound shells are influenced by pressure gradients and are pushed outward. The late-time evolution of the mass accretion rate Mdot is close to the result for pure dust, and we develop a semianalytic model that accurately accounts for the small effect of pressure gradients in this limit. In the opposite regime, ta,0/t0 ≪ 1, pressure forces significantly affect the motion of the gas. At sufficiently early times, t ≤ ttr, the flow evolved along a sequence of quasi-stationary, Bondi-like states, with a time-dependent Mdot determined by the slowly varying gas density at large distances. However, at later times, t ≥ ttr, the fluid flow enters a dustllke regime; ttr is the time when the instantaneous Bondi accretion radius reaches the marginally bound radius. The transition time ttr depends sensitively on ta,0/t0 for a given Γ and can greatly exceed t0. We show that there exists a critical value Γ = 11/9, below which the transition from fluid to ballistic motion disappears. As one application of our calculations, we consider the

  3. AstroCom NYC: Expanding the Partnership

    NASA Astrophysics Data System (ADS)

    Paglione, Timothy; Ford, Saavik; Agueros, Marcel A.; Mac Low, Mordecai-Mark; Robbins, Dennis

    2015-01-01

    AstroCom NYC is an undergraduate mentoring program designed to improve urban minority student access to opportunities in astrophysical research by greatly enhancing partnerships between research astronomers in New York City (City University of New York - an MSI, American Museum of Natural History, and Columbia). AstroCom NYC provides centralized, personalized mentoring as well as financial and academic support, to CUNY undergraduates throughout their studies, plus the resources and opportunities to further CUNY faculty research with students. The goal is that students' residency at AMNH helps them build a sense of belonging in the field, and readies and inspires them for graduate study. AstroCom NYC provides a rigorous Methods of Scientific Research course developed specifically to this purpose, a laptop, research and career mentors, outreach activities, scholarships and stipends, Metrocards, and regular assessment for maximum effectiveness. Stipends in part alleviate the burdens at home typical for CUNY students so they may concentrate on their academic success. AMNH serves as the central hub for our faculty and students, who are otherwise dispersed among all five boroughs of the City. For our second cohort, we dramatically improved the application and screening process, implemented a number of tools to evaluate their potential for grad school, and began growing a network of potential hosts for summer internships around NY State and the US. We review these implementations and outcomes, as well as plans for Year 3, when we expect many of our current students to compete for external summer REUs, and after greatly expanding the program reach through a NASA community college initiative.

  4. Expanding the boundaries of local similarity analysis

    PubMed Central

    2013-01-01

    Background Pairwise comparison of time series data for both local and time-lagged relationships is a computationally challenging problem relevant to many fields of inquiry. The Local Similarity Analysis (LSA) statistic identifies the existence of local and lagged relationships, but determining significance through a p-value has been algorithmically cumbersome due to an intensive permutation test, shuffling rows and columns and repeatedly calculating the statistic. Furthermore, this p-value is calculated with the assumption of normality -- a statistical luxury dissociated from most real world datasets. Results To improve the performance of LSA on big datasets, an asymptotic upper bound on the p-value calculation was derived without the assumption of normality. This change in the bound calculation markedly improved computational speed from O(pm2n) to O(m2n), where p is the number of permutations in a permutation test, m is the number of time series, and n is the length of each time series. The bounding process is implemented as a computationally efficient software package, FASTLSA, written in C and optimized for threading on multi-core computers, improving its practical computation time. We computationally compare our approach to previous implementations of LSA, demonstrate broad applicability by analyzing time series data from public health, microbial ecology, and social media, and visualize resulting networks using the Cytoscape software. Conclusions The FASTLSA software package expands the boundaries of LSA allowing analysis on datasets with millions of co-varying time series. Mapping metadata onto force-directed graphs derived from FASTLSA allows investigators to view correlated cliques and explore previously unrecognized network relationships. The software is freely available for download at: http://www.cmde.science.ubc.ca/hallam/fastLSA/. PMID:23368516

  5. Equations of motion in an Expanding Universe

    NASA Astrophysics Data System (ADS)

    Kopeikin, Sergei M.; Petrov, Alexander N.

    2015-06-01

    We make use of an effective field-theoretical approach to derive post-Newtonian equations of motion of hydrodynamical inhomogeneities in cosmology. The matter Lagrangian for the perturbed cosmological model includes dark matter, dark energy, and ordinary baryonic matter. The Lagrangian is expanded in an asymptotic Taylor series around a Friedmann-Lemaître-Robertson-Walker background. The small parameter of the decomposition is the magnitude of the metric tensor perturbation. Each term of the expansion series is gauge-invariant and all of them together form a basis for the successive post-Newtonian approximations around the background metric. The approximation scheme is covariant and the asymptotic nature of the Lagrangian decomposition does not require the post-Newtonian perturbations to be small though computationally it works the most effectively when the perturbed metric is close enough to the background metric. Temporal evolution of the background metric is governed by dark matter and dark energy and we associate the large-scale inhomogeneities of matter as those generated by the primordial cosmological perturbations in these two components with δρ/ρ ≤ 1. The small scale inhomogeneities are generated by the baryonic matter which is considered as a bare perturbation of the background gravitational field, dark matter and energy. Mathematically, the large scale structure inhomogeneities are given by the homogeneous solution of the post-Newtonian equations while the small scale inhomogeneities are described by a particular solution of these equations with the stress-energy tensor of the baryonic matter that admits δρ/ρ ≫ 1. We explicitly work out the field equations of the first post-Newtonian approximation in cosmology and derive the post-Newtonian equations of motion of the large and small scale inhomogeneities which generalize the covariant law of conservation of stress-energy-momentum tensor of matter in asymptotically-flat spacetime.

  6. Structural state of expanded graphite prepared from intercalation compounds

    SciTech Connect

    Teplykh, A. E. Bogdanov, S. G.; Dorofeev, Yu. A.; Pirogov, A. N.; Skryabin, Yu. N.; Makotchenko, V. G.; Nazarov, A. S.; Fedorov, V. E.

    2006-12-15

    The structural state of nanocrystalline samples of expanded graphite is investigated using X-ray diffraction and neutron diffraction analyses. The expanded graphite samples are prepared by a rapid thermal decomposition of intercalation compounds of oxidized graphite based on fluorinated graphite, graphite oxide, and graphite aminofluoride. It is established that the main phase of expanded graphite belongs to the hexagonal crystal system (space group P6{sub 3}/mmc) and that carbon atoms in the structure occupy the 2b and 2c positions. The unit cell parameters and the unit cell volume in the structure of expanded graphite samples are larger than those in the structure of massive graphite.

  7. Infrastructure Requirements for an Expanded Fuel Ethanol Industry

    SciTech Connect

    Reynolds, Robert E.

    2002-01-15

    This report provides technical information specifically related to ethanol transportation, distribution, and marketing issues. This report required analysis of the infrastructure requirements for an expanded ethanol industry.

  8. Expanding policy options for educating teenagers.

    PubMed

    Stern, David

    2009-01-01

    David Stern argues that some basic features of the American high school must be modified if it is to serve all students successfully. He notes, for example, that only three-quarters of U.S. high school students graduate four years after beginning ninth grade and that the National Assessment of Educational Progress found no improvement in reading or mathematics for seventeen-year-olds between 1971 and 2004. The nation's system for educating teenagers, says Stern, seems to be stuck, despite the constant efforts of teachers and repeated waves of reform. Citing two widely accepted public purposes of educating teenagers-preparation for civic participation and for economic self-sufficiency-Stern proposes four new strategies to achieve those goals. He draws on empirical evidence suggesting that these are promising directions for research and policy, but acknowledges that existing studies provide only limited guidance. First, he says, schools should continue the current trend toward integrating educational options to provide young people with skills and experiences that pave the way to both college and careers. Second, states and districts should tie education funding not simply to the number of students attending school, but also to what young people learn, whether they graduate, and whether they find jobs or enroll in postsecondary education. Such a move, he argues, would encourage teaching and learning formats that use students' time more effectively. Third, more adults in addition to classroom teachers should be involved in educating teenagers. Other adults acting as academic advisers, learning coaches, student advocates, internship supervisors, mentors, and college counselors could help guide the education of teenagers inside and outside of school and provide some relief for the chronic shortage of teachers. Fourth, schools should expand the options for educating teenagers outside of geographically fixed schools. Combining improved Internet-based curriculum with

  9. Expanding policy options for educating teenagers.

    PubMed

    Stern, David

    2009-01-01

    David Stern argues that some basic features of the American high school must be modified if it is to serve all students successfully. He notes, for example, that only three-quarters of U.S. high school students graduate four years after beginning ninth grade and that the National Assessment of Educational Progress found no improvement in reading or mathematics for seventeen-year-olds between 1971 and 2004. The nation's system for educating teenagers, says Stern, seems to be stuck, despite the constant efforts of teachers and repeated waves of reform. Citing two widely accepted public purposes of educating teenagers-preparation for civic participation and for economic self-sufficiency-Stern proposes four new strategies to achieve those goals. He draws on empirical evidence suggesting that these are promising directions for research and policy, but acknowledges that existing studies provide only limited guidance. First, he says, schools should continue the current trend toward integrating educational options to provide young people with skills and experiences that pave the way to both college and careers. Second, states and districts should tie education funding not simply to the number of students attending school, but also to what young people learn, whether they graduate, and whether they find jobs or enroll in postsecondary education. Such a move, he argues, would encourage teaching and learning formats that use students' time more effectively. Third, more adults in addition to classroom teachers should be involved in educating teenagers. Other adults acting as academic advisers, learning coaches, student advocates, internship supervisors, mentors, and college counselors could help guide the education of teenagers inside and outside of school and provide some relief for the chronic shortage of teachers. Fourth, schools should expand the options for educating teenagers outside of geographically fixed schools. Combining improved Internet-based curriculum with

  10. Expanding the scope of lamellar keratoplasty.

    PubMed Central

    Rich, L F

    1999-01-01

    PURPOSE: To investigate whether applications of current technology, such as cryolathe and excimer laser, might improve outcomes and increase use of lamellar keratoplasty. METHODS: Six studies were performed, beginning with animals and progressing to human subjects. The first study compared cryolathed with hand-dissected rabbit corneas to ascertain which created a smoother donor interface. The second animal pilot study was done to determine whether thickness of donor cornea resection could be accurately predicted with the cryolathe. A prospective animal trial was then undertaken to compare lamellar keratoplasty outcomes using cryolathed versus hand-dissected tissue. The fourth work extrapolated previous animal findings to lamellar keratoplasty in human disease. Finally, two ongoing studies are described. The first explores the possibility of sutureless lamellar keratoplasty. The second utilizes the excimer laser to dissect the recipient stromal bed. RESULTS: The initial animal pilot study demonstrated a clearer stromal surface in cryolathed versus hand-dissected corneal tissue. The second pilot showed that plano-powered donor tissue could be generated to predetermined thickness. The prospective animal trial revealed that clear grafts of intended thickness could be obtained with cryolathing. Human studies suggested that lamellar keratoplasty using cryolathe-prepared donor tissue may offer superior results to free-hand dissection. Finally, one ongoing study indicates that sutureless lamellar keratoplasty is untenable, and the other shows that clear grafts can be obtained by combining cryolathed donor tissue with recipient photoablation. CONCLUSION: This body of work demonstrates that use of new lamellar keratoplasty technology may offer expanded scope and better outcomes than traditional lamellar keratoplasty techniques. Images FIGURE 1 FIGURE 3 FIGURE 4A FIGURE 4B FIGURE 8A FIGURE 8B FIGURE 9 FIGURE 10 FIGURE 10B FIGURE 11A FIGURE 11B FIGURE 12A FIGURE 12B FIGURE 13

  11. In Vitro Comparison of Self-Expanding Versus Balloon-Expandable Stents in a Human Ex Vivo Model

    SciTech Connect

    Grenacher, Lars Rohde, Stefan Gaenger, Ellen; Deutsch, Jochen; Kauffmann, Guenter W.; Richter, Goetz M.

    2006-04-15

    The objective was to compare the radial strength and expansile precision of self-expanding stents and balloon-expandable stents in a human cadaver bifurcation model. Seven different self-expanding (LUMINEXX, JOSTENT SelfX, JOSTENT SelfX hrf, Sinus-Repo, Sinus SuperFlex, Easy Wallstent, SMART) and four different balloon-expandable stent models (Palmaz, Sinus Stent, SAXX Medium, JOSTENT peripheral), each type 10 stents (total n = 110 stents) were implanted into the common iliac arteries of human cadaver corpses. The maximum stent diameter was 10 mm for all models. After stent implantation, the specimens were filled with silicone caoutchouc. After 24 h, the vascular walls including the stents were removed from the hardened casts. Diameters were taken and the weight of the cast cylinders was measured in air and in purified water to calculate the volume of the bodies (according to Archimedes Law) as a relative but precise degree for the radial strength of the implanted stents. The cylindrical casts of the self-expanding stents showed lower mean diameters (8.2 {+-} 1.0 mm) and mean volumes (0.60 {+-} 0.14 ml/cm) than in the balloon-expandable stent group (10.1 {+-} 0.3 mm and 0.71 {+-} 0.04 ml/cm, respectively; p < 0.01). The nominal maximum diameter of 10 mm was not achieved in any of the self-expanding stents, but this was achieved in more than 70% (29/40) of the balloon-expandable stent specimens (p < 0.05). The variation between achieved volumes was significantly larger in self-expanding (range: 0.23-0.78 ml/cm) than in balloon-expandable stents (range: 0.66-0.81 ml/cm; p < 0.05). Self-expanding stents presented considerably lower radial expansion force and lower degree of precision than balloon-expandable stents.

  12. Study and design of beam expander with wide aperture

    NASA Astrophysics Data System (ADS)

    Guo, Ming; Jin, Guangyong; Cai, Jixing; Zhang, Wei; Wei, Zhi

    2014-12-01

    In order to improve the capacity of beam collimation for laser beam expander, it is necessary to design a more reasonable and feasible structure of beam expander system. Laser beam expander is used to compress the laser divergence angle, in order to reduce the energy losing in long distance scanning acquisition system. This paper introduces the working principle and design idea of the laser beam expander, the collimating multiplying power focal length and the collimated magnification formula of expander main, secondary mirror. According to the third-order aberration theory, Considering the spherical aberration, sine difference and divergence angle, the reasonable analysis of optical path, ZEMAX optical design software was used to design large-diameter laser beam expander and analysis and optimize, And given the actual design data and results. Display the maximum optical path difference is +/-0.01λ of the main light ray and each light ray. To combination the rear- group objective lens of Galileo and Kepler beam expander, a large-diameter(1.475m) laser beam expander was designed with 0.2m in the diameter, 1/2m in the relative caliber. In the objective lens System, a high-order aspherical was used to the aberration of extra-axial point. we can see that the image quality is close to the diffraction limit from the curves of wavefront. In addition to improve image quality effectively, the system has the characteristics of simple structure, less costly and less design difficulty to compare with the other beam expanding system. And make the output beam's divergence angle smaller, energy density higher, and the beam quality has been greatly improved. The results show that the beam expander is fully meet the design requirements, the use effect is good. Design and research of laser beam expanding system not only improves the quality of the laser beam in the laser system, but also enlarge the application field of laser technology in photoelectric system.

  13. Expanding the Horizons of Quantitative Remote Sensing

    NASA Astrophysics Data System (ADS)

    Christensen, P. R.

    2011-12-01

    and deconvolved with a similarly degraded and reduced spectral library, whose endmember selection was informed by the hyperspectral results. Using these carefully chosen endmembers, the deconvolved spectra provide results that are similar to the hyperspectral analysis in many, but not all cases; future work is needed to understand exactly why and when. Analysis of high-spectral-resolution data reveals that the subtle spectral variations present in the multi-spectral data represent true variations in surface composition. Nine distinct compositional units can be identified, with subtle composition variations within these units that are confirmed by analysis of spectra of collected samples and field inspection. This compositional mapping is accurate enough to confidently map the details of the highly complex, structurally rotated and thrusted terrain of the Granite Wash Mtns, Arizona. This work illustrates that even a limited amount of high spectral and spatial resolution data provide extremely powerful tools to extend the analysis of the satellite multi-spectral data, significantly increasing the accuracy of, and confidence in, the use of these data for quantitative compositional mapping. Until hyperspectral remote sensing systems become available, these approaches provide a means to meaningfully expand the utility and use of existing multi-spectral data.

  14. Challenging the Expanding Environment Model of Teaching Elementary Social Studies.

    ERIC Educational Resources Information Center

    Palmer, Jesse

    1989-01-01

    Looks at criticism of the Expanding Environments Model in the elementary school social studies curriculum. Cites recent reports that recommend a history-centered elementary curriculum. States that teaching methods may be the cause of historical, civic, and geographic illiteracy rather than the Expanding Environments Model. (LS)

  15. New York: Expanding Time, Increasing Opportunities for Achievement

    ERIC Educational Resources Information Center

    Miller, Tiffany D.

    2014-01-01

    New York is poised to take an important step to improve student achievement by expanding learning time for students attending high-poverty, low-performing schools. Recent district- and state-level investments in expanded learning time--a promising strategy to close achievement and opportunity gaps--will give students more time to learn core…

  16. Still Not Equal: Expanding Educational Opportunity in Society

    ERIC Educational Resources Information Center

    Brown, M. Christopher, II, Ed.

    2007-01-01

    "Still Not Equal: Expanding Educational Opportunity in Society" addresses the successes and failures of "Brown v. Board of Education" and the Civil Rights Act of 1964, as well as the continuing challenge of expanding educational opportunity in the United States and across the Black diaspora. The educational, political, and social influence…

  17. Supporting Student Success: The Promise of Expanded Learning Opportunities

    ERIC Educational Resources Information Center

    NGA Center for Best Practices, 2010

    2010-01-01

    Expanded learning opportunities (ELOs) support state education goals by providing safe, structured learning environments for students outside the regular school day. ELOs include after-school and summer learning programs, as well as before-school, evening, and weekend programs. Although research demonstrates that high-quality expanded learning…

  18. Characteristics and Young's Modulus of Collagen Fibrils from Expanded Skin Using Anisotropic Controlled Rate Self-Inflating Tissue Expander.

    PubMed

    Manssor, Nur Aini S; Radzi, Zamri; Yahya, Noor Azlin; Mohamad Yusof, Loqman; Hariri, Firdaus; Khairuddin, Nurul Hayah; Abu Kasim, Noor Hayaty; Czernuszka, Jan T

    2016-01-01

    Mechanical properties of expanded skin tissue are different from normal skin, which is dependent mainly on the structural and functional integrity of dermal collagen fibrils. In the present study, mechanical properties and surface topography of both expanded and nonexpanded skin collagen fibrils were evaluated. Anisotropic controlled rate self-inflating tissue expanders were placed beneath the skin of sheep's forelimbs. The tissue expanders gradually increased in height and reached equilibrium in 2 weeks. They were left in situ for another 2 weeks before explantation. Expanded and normal skin samples were surgically harvested from the sheep (n = 5). Young's modulus and surface topography of collagen fibrils were measured using an atomic force microscope. A surface topographic scan showed organized hierarchical structural levels: collagen molecules, fibrils and fibers. No significant difference was detected for the D-banding pattern: 63.5 ± 2.6 nm (normal skin) and 63.7 ± 2.7 nm (expanded skin). Fibrils from expanded tissues consisted of loosely packed collagen fibrils and the width of the fibrils was significantly narrower compared to those from normal skin: 153.9 ± 25.3 and 106.7 ± 28.5 nm, respectively. Young's modulus of the collagen fibrils in the expanded and normal skin was not statistically significant: 46.5 ± 19.4 and 35.2 ± 27.0 MPa, respectively. In conclusion, the anisotropic controlled rate self-inflating tissue expander produced a loosely packed collagen network and the fibrils exhibited similar D-banding characteristics as the control group in a sheep model. However, the fibrils from the expanded skin were significantly narrower. The stiffness of the fibrils from the expanded skin was higher but it was not statistically different. PMID:26836267

  19. Distant Supernovae Indicate Ever-Expanding Universe

    NASA Astrophysics Data System (ADS)

    1998-12-01

    ESO Astronomers Contribute towards Resolution of Cosmic Puzzle Since the discovery of the expansion of the Universe by American astronomer Edwin Hubble in the 1920's, by measurement of galaxy velocities, astronomers have tried to learn how this expansion changes with time. Until now, most scientists have been considering two possibilities: the expansion rate is slowing down and will ultimately either come to a halt - whereafter the Universe would start to contract, or it will continue to expand forever. However, new studies by two independent research teams, based on observations of exploding stars ( supernovae ) by ESO astronomers [1] with astronomical telescopes at the La Silla Observatory as well as those of their colleagues at other institutions, appear to show that the expansion of the Universe is accelerating . The results take the discovery of the cosmological expansion one step further and challenge recent models of the Universe. If the new measurements are indeed correct, they show that the elusive "cosmological constant" , as proposed by Albert Einstein , contributes significantly to the evolution of the Universe. The existence of a non-zero cosmological constant implies that a repulsive force, counter-acting gravity, currently dominates the universal expansion , and consequently leads to an ever-expanding Universe. This new research is being named as the "Breakthrough of the Year" by the renowned US science journal Science in the December 18, 1998, issue. A Press Release is published by the journal on this occasion. "Fundamental Parameters" of the Universe Three fundamental parameters govern all cosmological models based on the theory of General Relativity. They are 1. the current expansion rate as described by Hubble's constant , i.e. the proportionality factor between expansion velocity and distance 2. the average matter density in the Universe, and 3. the amount of "other energy" present in space. From the measured values of these fundamental

  20. Tissue regeneration during tissue expansion and choosing an expander

    PubMed Central

    Agrawal, K.; Agrawal, S.

    2012-01-01

    This paper reviews the various aspects of tissue regeneration during the process of tissue expansion. “Creep” and mechanical and biological “stretch” are responsible for expansion. During expansion, the epidermis thickens, the dermis thins out, vascularity improves, significant angiogenesis occurs, hair telogen phase becomes shorter and the peripheral nerves, vessels and muscle fibres lengthen. Expansion is associated with molecular changes in the tissue. Almost all these biological changes are reversible after the removal of the expander.This study is also aimed at reviewing the difficulty in deciding the volume and dimension of the expander for a defect. Basic mathematical formulae and the computer programmes for calculating the dimension of tissue expanders, although available in the literature, are not popular. A user-friendly computer programme based on the easily available Microsoft Excel spread sheet has been introduced. When we feed the area of defect and base dimension of the donor area or tissue expander, this programme calculates the volume and height of the expander. The shape of the expander is decided clinically based on the availability of the donor area and the designing of the future tissue movement. Today, tissue expansion is better understood biologically and mechanically. Clinical judgement remains indispensable in choosing the size and shape of the tissue expander. PMID:22754146

  1. Acute expanded perlite exposure with persistent reactive airway dysfunction syndrome.

    PubMed

    Du, Chung-Li; Wang, Jung-Der; Chu, Po-Chin; Guo, Yue-Liang Leon

    2010-01-01

    Expanded perlite has been assumed as simple nuisance, however during an accidental spill out in Taiwan, among 24 exposed workers followed for more than 6 months, three developed persisted respiratory symptoms and positive provocation tests were compatible with reactive airway dysfunction syndrome. During simulation experiment expanded perlite is shown to be very dusty and greatly exceed current exposure permission level. Review of literature and evidence, though exposure of expanded perlite below permission level may be generally safe, precautionary protection of short term heavy exposure is warranted.

  2. Nitrogen expander cycles for large capacity liquefaction of natural gas

    SciTech Connect

    Chang, Ho-Myung; Park, Jae Hoon; Gwak, Kyung Hyun; Choe, Kun Hyung

    2014-01-29

    Thermodynamic study is performed on nitrogen expander cycles for large capacity liquefaction of natural gas. In order to substantially increase the capacity, a Brayton refrigeration cycle with nitrogen expander was recently added to the cold end of the reputable propane pre-cooled mixed-refrigerant (C3-MR) process. Similar modifications with a nitrogen expander cycle are extensively investigated on a variety of cycle configurations. The existing and modified cycles are simulated with commercial process software (Aspen HYSYS) based on selected specifications. The results are compared in terms of thermodynamic efficiency, liquefaction capacity, and estimated size of heat exchangers. The combination of C3-MR with partial regeneration and pre-cooling of nitrogen expander cycle is recommended to have a great potential for high efficiency and large capacity.

  3. Environmental assessment, expanded Ponnequin wind energy project, Weld County, Colorado

    SciTech Connect

    1999-02-01

    The US Department of Energy (DOE) has considered a proposal from the State of Colorado, Office of Energy Conservation (OEC), for funding construction of the Expanded Ponnequin Wind Project in Weld County, Colorado. OEC plans to enter into a contracting arrangement with Public Service Company of Colorado (PSCo) for the completion of these activities. PSCo, along with its subcontractors and business partners, are jointly developing the Expanded Ponnequin Wind Project. The purpose of this Final Environmental Assessment (EA) is to provide DOE and the public with information on potential environmental impacts associated with the Expanded Ponnequin Wind Energy Project. This EA, and public comments received on it, were used in DOE`s deliberations on whether to release funding for the expanded project under the Commercialization Ventures Program.

  4. growl: Growth factor and growth rate of expanding universes

    NASA Astrophysics Data System (ADS)

    Hamilton, Andrew J. S.

    2015-12-01

    Growl calculates the linear growth factor Da and its logarithmic derivative dln D/dln a in expanding Friedmann-Robertson-Walker universes with arbitrary matter and vacuum densities. It permits rapid and stable numerical evaluation.

  5. The Rate of Expanded Inner Speech During Spontaneous Sentence Productions.

    PubMed

    Netsell, Ronald; Kleinsasser, Steven; Daniel, Todd

    2016-10-01

    The rate of expanded inner speech and speech aloud was compared in 20 typical adults (3 males, 17 females; M age = 24 years, SD = 4). Participants generated and timed spontaneous sentences with both expanded inner speech and speech aloud following the instruction to say "the first thing that comes to mind." The rate of expanded inner speech was slightly, but significantly, faster than the rate of speech aloud. The findings supported the hypothesis that expanded inner speech was faster than speech aloud because of the time required to move the articulators in the latter. Physical measures of speaking rate are needed to validate self-timed measures. Limitations of the study and directions for research are discussed. PMID:27562695

  6. Expanding the Intertrial Interval During Extinction: Response Cessation and Recovery

    PubMed Central

    Orinstein, Alyssa J.; Urcelay, Gonzalo P.; Miller, Ralph R.

    2010-01-01

    We examined trial spacing during extinction following a human contingency learning task. Specifically, we assessed if an expanding retrieval practice schedule (Bjork & Bjork, 1992, 2006), in which the spacing between extinction trials was progressively increased, would result in faster immediate extinction and less recovery from extinction than uniformly spaced extinction trials. We used an ABB vs. ABA renewal design and observed that, whereas the expanding group extinguished faster during extinction treatment, the expanding and constant groups showed the same level of extinction with an immediate test in the extinction context (ABB) and the two groups showed equivalent ABA renewal at test in the training context. We conclude that the faster extinction observed in the expanding groups could be misleading in clinical treatment, if the therapist used the absence of fear during extinction as the basis for terminating treatment. PMID:20171324

  7. Analytic Solution of the Boltzmann Equation in an Expanding System.

    PubMed

    Bazow, D; Denicol, G S; Heinz, U; Martinez, M; Noronha, J

    2016-01-15

    For a massless gas with a constant cross section in a homogeneous, isotropically expanding spacetime we reformulate the relativistic Boltzmann equation as a set of nonlinear coupled moment equations. For a particular initial condition this set can be solved exactly, yielding the first analytical solution of the Boltzmann equation for an expanding system. The nonequilibrium behavior of this relativistic gas can be mapped onto that of a homogeneous, static nonrelativistic gas of Maxwell molecules. PMID:26824535

  8. Shifted genus expanded W ∞ algebra and shifted Hurwitz numbers

    NASA Astrophysics Data System (ADS)

    Zheng, Quan

    2016-05-01

    We construct the shifted genus expanded W ∞ algebra, which is isomorphic to the central subalgebra A ∞ of infinite symmetric group algebra and to the shifted Schur symmetrical function algebra Λ* defined by Okounkov and Olshanskii. As an application, we get some differential equations for the generating functions of the shifted Hurwitz numbers; thus, we can express the generating functions in terms of the shifted genus expanded cut-and-join operators.

  9. A new magnetic expanded graphite for removal of oil leakage.

    PubMed

    Ding, Xiaohui; Wang, Rong; Zhang, Xin; Zhang, Yanzong; Deng, Shihuai; Shen, Fei; Zhang, Xiaohong; Xiao, Hong; Wang, Lilin

    2014-04-15

    Magnetic expanded graphite (MEG) was prepared using the blended calcination method under a nitrogen atmosphere. MEG was characterized by scanning electron microscope (SEM), X-ray powder diffraction (XRD), Raman spectroscopy, and vibrating sample magnetization (VSM). Results show that the cobalt ferrite nanoparticles were uniformly and efficiently deposited on expanded graphite (EG). The saturation magnetization reached 55.05 emu g(-1), and the adsorption capacity of MEG under the optimal condition was 35.72 g g(-1) for crude oil.

  10. Self-expanding/shrinking structures by 4D printing

    NASA Astrophysics Data System (ADS)

    Bodaghi, M.; Damanpack, A. R.; Liao, W. H.

    2016-10-01

    The aim of this paper is to create adaptive structures capable of self-expanding and self-shrinking by means of four-dimensional printing technology. An actuator unit is designed and fabricated directly by printing fibers of shape memory polymers (SMPs) in flexible beams with different arrangements. Experiments are conducted to determine thermo-mechanical material properties of the fabricated part revealing that the printing process introduced a strong anisotropy into the printed parts. The feasibility of the actuator unit with self-expanding and self-shrinking features is demonstrated experimentally. A phenomenological constitutive model together with analytical closed-form solutions are developed to replicate thermo-mechanical behaviors of SMPs. Governing equations of equilibrium are developed for printed structures based on the non-linear Green-Lagrange strain tensor and solved implementing a finite element method along with an iterative incremental Newton-Raphson scheme. The material-structural model is then applied to digitally design and print SMP adaptive lattices in planar and tubular shapes comprising a periodic arrangement of SMP actuator units that expand and then recover their original shape automatically. Numerical and experimental results reveal that the proposed planar lattice as meta-materials can be employed for plane actuators with self-expanding/shrinking features or as structural switches providing two different dynamic characteristics. It is also shown that the proposed tubular lattice with a self-expanding/shrinking mechanism can serve as tubular stents and grippers for bio-medical or piping applications.

  11. Numerical simulation of a twin screw expander for performance prediction

    NASA Astrophysics Data System (ADS)

    Papes, Iva; Degroote, Joris; Vierendeels, Jan

    2015-08-01

    With the increasing use of twin screw expanders in waste heat recovery applications, the performance prediction of these machines plays an important role. This paper presents a mathematical model for calculating the performance of a twin screw expander. From the mass and energy conservation laws, differential equations are derived which are then solved together with the appropriate Equation of State in the instantaneous control volumes. Different flow processes that occur inside the screw expander such as filling (accompanied by a substantial pressure loss) and leakage flows through the clearances are accounted for in the model. The mathematical model employs all geometrical parameters such as chamber volume, suction and leakage areas. With R245fa as working fluid, the Aungier Redlich-Kwong Equation of State has been used in order to include real gas effects. To calculate the mass flow rates through the leakage paths formed inside the screw expander, flow coefficients are considered as constant and they are derived from 3D Computational Fluid Dynamic calculations at given working conditions and applied to all other working conditions. The outcome of the mathematical model is the P-V indicator diagram which is compared to CFD results of the same twin screw expander. Since CFD calculations require significant computational time, developed mathematical model can be used for the faster performance prediction.

  12. Theoretically Founded Optimization of Auctioneer's Revenues in Expanding Auctions

    NASA Astrophysics Data System (ADS)

    Rabin, Jonathan; Shehory, Onn

    The expanding auction is a multi-unit auction which provides the auctioneer with control over the outcome of the auction by means of dynamically adding items for sale. Previous research on the expanding auction has provided a numeric method to calculate a strategy that optimizes the auctioneer's revenue. In this paper, we analyze various theoretical properties of the expanding auction, and compare it to VCG, a multi-unit auction protocol known in the art. We examine the effects of errors in the auctioneer's estimation of the buyers' maximal bidding values and prove a theoretical bound on the ratio between the revenue yielded by the Informed Decision Strategy (IDS) and the post-optimal strategy. We also analyze the relationship between the auction step and the optimal revenue and introduce a method of computing this optimizing step. We further compare the revenues yielded by the use of IDS with an expanding auction to those of the VCG mechanism and determine the conditions under which the former outperforms the latter. Our work provides new insight into the properties of the expanding auction. It further provides theoretically founded means for optimizing the revenue of auctioneer.

  13. SLOW MAGNETOACOUSTIC WAVE OSCILLATION OF AN EXPANDING CORONAL LOOP

    SciTech Connect

    Schmidt, J. M.; Ofman, L.

    2011-10-01

    We simulated an expanding loop or slow coronal mass ejection (CME) in the solar corona dimensioned with size parameters taken from real coronal expanding loops observed with the STEREO spacecraft. We find that the loop expands to Sun's size within about one hour, consistent with slow CME observations. At the top of the loop, plasma is being blown off the loop, enabled with the reconnection between the loop's flux rope magnetic field and the radial magnetic field of the Sun, thus yielding feeding material for the formation of the slow solar wind. This mechanism is in accordance with the observed blob formation of the slow solar wind. We find wave packets traveling with local sound speed downward toward the footpoints of the loop, already seen in coronal seismology observations and simulations of stationary coronal loops. Here, we generalize these results for an expanding medium. We also find a reflection of the wave packets, identified as slow magnetoacoustic waves, at the footpoints of the loop. This confirms the formation of standing waves within the coronal loop. In particular, the reflected waves can partly escape the loop top and contribute to the heating of the solar wind. The present study improves our understanding on how loop material can emerge to form blobs, major ingredients of slow CMEs, and how the release of the wave energy stored in slow magnetoacoustic waves, and transported away from the Sun within expanding loops, contributes to the acceleration and formation of the slow solar wind.

  14. Testing the Expanding-Contracting Polar Cap Paradigm

    NASA Astrophysics Data System (ADS)

    Sotirelis, T.; Keller, M. R.; Smith, D.; Barnes, R. J.; Talaat, E. R.; Newell, P. T.; Baker, J. B.

    2013-12-01

    The expanding-contracting polar cap (ECPC) paradigm is tested. Under the ECPC paradigm ionospheric convection in the polar cap is driven by the combined effects of dayside merging and nightside reconnection, as opposed to being mapped down from higher altitudes. The ECPC paradigm is tested by separately examining convection when the polar cap is expanding versus contracting. The open magnetic flux is estimated from SuperDARN observations of the convection reversal boundary (CRB) made simultaneously at different local times. (Sotirelis et al. [2005] established the CRB as a proxy for the Open-Closed Boundary (OCB).) The correlation of the ionospheric convection potential with solar wind/IMF driving is indeed found to depend on whether the polar cap is expanding or contracting. Specifically, when the polar cap is expanding, ionospheric convection correlates best (0.86) with the most recent 10 minutes of solar wind/IMF driving (versus 0.57 for contracting). When contracting, convection correlates best (0.87) with 90-minute averages of solar wind/IMF driving (versus 0.51 for expanding). This is consistent with ECPC expectations.

  15. An Expanded CAG Repeat in Huntingtin Causes +1 Frameshifting.

    PubMed

    Saffert, Paul; Adamla, Frauke; Schieweck, Rico; Atkins, John F; Ignatova, Zoya

    2016-08-26

    Maintenance of triplet decoding is crucial for the expression of functional protein because deviations either into the -1 or +1 reading frames are often non-functional. We report here that expression of huntingtin (Htt) exon 1 with expanded CAG repeats, implicated in Huntington pathology, undergoes a sporadic +1 frameshift to generate from the CAG repeat a trans-frame AGC repeat-encoded product. This +1 recoding is exclusively detected in pathological Htt variants, i.e. those with expanded repeats with more than 35 consecutive CAG codons. An atypical +1 shift site, UUC C at the 5' end of CAG repeats, which has some resemblance to the influenza A virus shift site, triggers the +1 frameshifting and is enhanced by the increased propensity of the expanded CAG repeats to form a stem-loop structure. The +1 trans-frame-encoded product can directly influence the aggregation of the parental Htt exon 1. PMID:27382061

  16. Financial Burdens and Economic Costs in Expanding Urban Water Systems

    NASA Astrophysics Data System (ADS)

    Moreau, David H.; Snyder, Thomas P.

    1987-07-01

    Rates of growth of demand, lengths of financing periods, real interest rates, and the types of facilities are shown to be important variables in evaluating the equity (or inequity) between established residents and new-development residents when urban water and sewer facilities are expanded with public financing. Established residents pay less than the economic cost of facilities when facilities that can be efficiently expanded in an incremental manner are subject to demands that are growing at rates that are less than the real interest rate. They pay more than the economic cost when growth occurs at higher rates. When facilities are expanded at multiyear intervals with excess capacity, payments are equated to costs at lower growth rates. Similarly, increasing real costs of facilities shift that breakpoint to lower growth rates. Modest one-time changes can be used to offset burdens on established residents when inequities do occur. Inflation has little effect on these results.

  17. The effect of code expanding optimizations on instruction cache design

    NASA Technical Reports Server (NTRS)

    Chen, William Y.; Chang, Pohua P.; Conte, Thomas M.; Hwu, Wen-Mei W.

    1991-01-01

    It is shown that code expanding optimizations have strong and non-intuitive implications on instruction cache design. Three types of code expanding optimizations are studied: instruction placement, function inline expansion, and superscalar optimizations. Overall, instruction placement reduces the miss ratio of small caches. Function inline expansion improves the performance for small cache sizes, but degrades the performance of medium caches. Superscalar optimizations increases the cache size required for a given miss ratio. On the other hand, they also increase the sequentiality of instruction access so that a simple load-forward scheme effectively cancels the negative effects. Overall, it is shown that with load forwarding, the three types of code expanding optimizations jointly improve the performance of small caches and have little effect on large caches.

  18. Can microcarrier-expanded chondrocytes synthesize cartilaginous tissue in vitro?

    PubMed

    Surrao, Denver C; Khan, Aasma A; McGregor, Aaron J; Amsden, Brian G; Waldman, Stephen D

    2011-08-01

    Tissue engineering is a promising approach for articular cartilage repair; however, it is challenging to produce adequate amounts of tissue in vitro from the limited number of cells that can be extracted from an individual. Relatively few cell expansion methods exist without the problems of de-differentiation and/or loss of potency. Recently, however, several studies have noted the benefits of three-dimensional (3D) over monolayer expansion, but the ability of 3D expanded chondrocytes to synthesize cartilaginous tissue constructs has not been demonstrated. Thus, the purpose of this study was to compare the properties of engineered cartilage constructs from expanded cells (monolayer and 3D microcarriers) to those developed from primary chondrocytes. Isolated bovine chondrocytes were grown for 3 weeks in either monolayer (T-Flasks) or 3D microcarrier (Cytodex 3) expansion culture. Expanded and isolated primary cells were then seeded in high density culture on Millicell™ filters for 4 weeks to evaluate the ability to synthesize cartilaginous tissue. While microcarrier expansion was twice as effective as monolayer expansion (microcarrier: 110-fold increase, monolayer: 52-fold increase), the expanded cells (monolayer and 3D microcarrier) were not effectively able to synthesize cartilaginous tissue in vitro. Tissues developed from primary cells were substantially thicker and accumulated significantly more extracellular matrix (proteoglycan content: 156%-292% increase; collagen content: 70%-191% increase). These results were attributed to phenotypic changes experienced during the expansion phase. Monolayer expanded chondrocytes lost their native morphology within 1 week, whereas microcarrier-expanded cells were spreading by 3 weeks of expansion. While the use of 3D microcarriers can lead to large cellular yields, preservation of chondrogenic phenotype during expansion is required in order to synthesize cartilaginous tissue. PMID:21449621

  19. Stability of the anisotropically inflating Bianchi type VI expanding solutions

    SciTech Connect

    Kao, W. F.; Lin, Ing-Chen

    2011-03-15

    A special class of the Bianchi type VI expanding solutions was speculated to break the cosmic no-hair theorem that will not approach the late-time de Sitter solution. We will show that an unstable mode always exists when the perturbation of the field equations is applied to the system. In addition to a model-independent perturbation formula, a simplification is also achieved by the introduction of a {delta}R=0 solution good for quadratic models in all Bianchi spaces. The result shows that this special class of anisotropically expanding solutions is unstable.

  20. Uniformly expanding vacuum: A possible interpretation of the dark energy

    NASA Astrophysics Data System (ADS)

    Huang, Peng; Yuan, Fang-Fang

    2016-06-01

    Following the spirit of the equivalence principle, we take a step further to recognize the free fall of the observer as a method to eliminate causes that would lead the perceived vacuum to change its original state. Thus, it is expected that the vacuum should be in a rigid Minkowski state or be uniformly expanding. By carefully investigating the impact on measurement caused by the expansion, we clarify the exact meaning of the uniformly expanding vacuum and find that this proposal may be able to explain the current observations of an accelerating universe.

  1. The paradox of HIV/AIDS as expanding consciousness.

    PubMed

    Lamendola, F P; Newman, M A

    1994-03-01

    A heuristic approach employing Newman's method for pattern identification was used to examine the theory of health as expanding consciousness in persons with human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS). Themes derived from the interview of nine gay men portrayed a pattern of alienation during childhood, followed by a breaking away from family, and progressing to cycles of aloneness and searching. Recognition of HIV/AIDS in their lives brought them to a turning point of more meaningful connectedness. This pattern is viewed as expanding consciousness and possibly a phenomenon of cultural evolution. PMID:8203827

  2. Preparation and characterization of low-temperature expandable graphite

    SciTech Connect

    Ying Zongrong Lin Xuemei; Qi Yu; Luo Jie

    2008-10-02

    The low-temperature expandable graphite was successfully prepared with perchloric acid, phosphoric acid and KMnO{sub 4} by chemical process. The optimum weight ratio of perchloric acid to phosphoric acid in mixed acid was 1:0.2, and the weight ratio of the mixed acid, KMnO{sub 4} and natural flake graphite was preferably 1.5:0.1:1. The expanded volume can reach 260 mL/g at a relatively low temperature of 300 deg. C. Meanwhile, the prepared samples were characterized by means of Fourier transform infrared, thermogravimetry-differential scanning calorimetry and X-ray diffraction.

  3. Self-expandable CoreValve implantation without contrast media.

    PubMed

    Bruschi, Giuseppe; Colombo, Paola; De Marco, Federico; Barosi, Alberto; Mauri, Silvia; Klugmann, Silvio

    2016-09-01

    Transcatheter aortic valve implantation has been designed to treat high-risk surgical patients affected by severe aortic stenosis, many of whom are affected by chronic kidney disease. To perform transcatheter self-expandable valve implantation, multiple contrast injections are required to monitor the procedure, so these patients are at increased risk of acute kidney injury. We described self-expandable transcatheter aortic valve implantation without contrast media in an 80-year-old man affected by severe aortic stenosis and endstage chronic kidney disease.

  4. Solubility parameter of poly(tetrafluoroethylene)

    NASA Astrophysics Data System (ADS)

    Wohlfarth, Ch.

    This document is part of Subvolume D2 'Polymer Solutions - Physical Properties and their Relations I (Thermodynamic Properties: PVT -Data and miscellaneous Properties of polymer Solutions) of Volume 6 `Polymers' of Landolt-Börnstein - Group VIII `Advanced Materials and Technologies'.

  5. Expanding Distribution of Lethal Amphibian Fungus Batrachochytrium salamandrivorans in Europe.

    PubMed

    Spitzen-van der Sluijs, Annemarieke; Martel, An; Asselberghs, Johan; Bales, Emma K; Beukema, Wouter; Bletz, Molly C; Dalbeck, Lutz; Goverse, Edo; Kerres, Alexander; Kinet, Thierry; Kirst, Kai; Laudelout, Arnaud; Marin da Fonte, Luis F; Nöllert, Andreas; Ohlhoff, Dagmar; Sabino-Pinto, Joana; Schmidt, Benedikt R; Speybroeck, Jeroen; Spikmans, Frank; Steinfartz, Sebastian; Veith, Michael; Vences, Miguel; Wagner, Norman; Pasmans, Frank; Lötters, Stefan

    2016-07-01

    Emerging fungal diseases can drive amphibian species to local extinction. During 2010-2016, we examined 1,921 urodeles in 3 European countries. Presence of the chytrid fungus Batrachochytrium salamandrivorans at new locations and in urodeles of different species expands the known geographic and host range of the fungus and underpins its imminent threat to biodiversity.

  6. Contracting/expanding self-sealing cryogenic tube seals

    NASA Technical Reports Server (NTRS)

    Jia, Lin X. (Inventor)

    1997-01-01

    Contracting/expanding self-sealing cryogenic tube seals are disclosed which use the different properties of thermal contraction and expansion of selected dissimilar materials in accord with certain design criteria to yield self-tightening seals via sloped-surface sealing. The seals of the subject invention are reusable, simple to assemble, and adaptable to a wide variety of cryogenic applications.

  7. Expanding Dual Enrollment: Increasing Postsecondary Access for All?

    ERIC Educational Resources Information Center

    Pretlow, Josh; Wathington, Heather D.

    2014-01-01

    This study investigated the dual enrollment outcomes associated with a 2005 policy change intended to expand dual enrollment participation in Virginia. Results indicated that overall access to and participation in dual enrollment courses increased following the policy change. However, data showed this increase was not uniform, and minority groups…

  8. Substance Abuse Prevention and Intervention: An Expanded Perspective for Counselors.

    ERIC Educational Resources Information Center

    Schmidt, John J.

    1994-01-01

    Suggests that a successful "war" on alcohol and other drug abuse requires cooperation among counselors and other helping professionals, beginning among professional counselors. View of counselors' roles must be expanded, as well as those of schools, government agencies, law enforcement officials, health professionals, and recreational specialists.…

  9. The Expanded Food and Nutrition Education Program (EFNEP)

    ERIC Educational Resources Information Center

    National Institute of Food and Agriculture, 2010

    2010-01-01

    Obesity, poor health, and limited physical activity are major health concerns. The Expanded Food and Nutrition Education Program (EFNEP) improves the health and well-being of limited resource families and youth. Additionally, EFNEP leads to public savings. Research shows that better health is associated with reduced health care costs, less…

  10. Expandable rubber plug seals openings for pressure testing

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Plug assembly seals openings in piping systems, vessels, and chambers for low pressure leak testing. The assembly, which consists of a rubber sealing plug and the mechanism for expanding it into a pressure-tight configuration, adequately seals irregular diameters without damage to mating surfaces.

  11. Shifting Expectations: Bringing STEM to Scale through Expanded Learning Systems

    ERIC Educational Resources Information Center

    Donner, Jessica; Wang, Yvonne

    2013-01-01

    Expanded learning opportunities, such as afterschool and summer programs, are particularly well positioned to help address science, technology, engineering, and mathematics (STEM) education crisis. A large percentage of youth participating in afterschool programs are members of groups traditionally underrepresented in STEM fields. Additionally,…

  12. Expanding Gerontology Enrollments: Successful Results of an Innovative Outreach Program

    ERIC Educational Resources Information Center

    Reynolds, Sandra L.; Haley, William E.; Hyer, Kathryn

    2007-01-01

    As state budget allocations for higher education decrease, "specialty" programs such as gerontology must continually demonstrate their productivity. State and private universities increasingly rely on student credit hours (SCH) or tuition generated, which is making it difficult for many gerontology programs to expand. The School of Aging Studies…

  13. Educated Japanese English: Expanding Oral/Aural Core Vocabulary

    ERIC Educational Resources Information Center

    D'Angelo, James F.

    2005-01-01

    Having established the world's first undergraduate college of world Englishes, and in an "Expanding-Circle" setting, we have created the pilot environment for a new type of ELT curriculum. We must address the creation of a curriculum that is pervasively informed by the philosophy of world Englishes at both a macro and micro level. Certain…

  14. Expanding the Oral Hygiene Curriculum in a Nursing Program.

    ERIC Educational Resources Information Center

    Briggs, Susan; Griego, Elizabeth

    A program was implemented to expand the curriculum materials within the Licensed Practical Nursing (LPN) Program at Clark County Community College (CCCC) which relate to oral hygiene care for the hospital patient. The instructional materials included a video tape and a written instructional packet which were researched, prepared, and presented by…

  15. Microcomputer Telecommunication: Bringing Education Online for an Expanded Classroom.

    ERIC Educational Resources Information Center

    Schooler, Douglas K.

    This document is designed as a comprehensive resource and guide for computer-using educators who wish to expand the scope and magnitude of their computer power through telecommunications. The major focus is on the microcomputer's ability to communicate with other microcomputers via telephone lines. Emphasis is placed upon information services and…

  16. Crowd Around: Expanding Your Donor Pool with Crowdfunding

    ERIC Educational Resources Information Center

    Jarrell, Andrea

    2013-01-01

    At most institutions, annual fund-giving is down. Crowdfunding sites allow people with a great idea or worthy cause to bypass traditional funding methods and take their case directly to web-savvy investors and donors. This article describes how higher education institutions are expanding their donor pool through such crowdfunding sites as USEED,…

  17. Expanding Schooling Opportunities for 4-Year-Olds

    ERIC Educational Resources Information Center

    Leuven, Edwin; Lindahl, Mikael; Oosterbeek, Hessel; Webbink, Dinand

    2010-01-01

    We use a novel quasi-experimental strategy to estimate the effect of expanding early schooling enrollment possibilities on early achievement. It exploits two features of the school system in The Netherlands. The first is rolling admissions; children are allowed to start school immediately after their 4th birthday instead of at the beginning of the…

  18. 78 FR 37431 - Expanding America's Leadership in Wireless Innovation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-20

    .... (Presidential Sig.) THE WHITE HOUSE, Washington, June 14, 2013. [FR Doc. 2013-14971 Filed 6-19-13; 11:15 am... Documents#0;#0; ] Memorandum of June 14, 2013 Expanding America's Leadership in Wireless Innovation... innovation, private investment, and smart policy has positioned the United States as the global leader...

  19. Strengthening and Expanding Prekindergarten in the Children First Reorganization

    ERIC Educational Resources Information Center

    Boressoff, Todd

    2012-01-01

    This policy brief examines the infrastructure needed to support early education at the Department of Education in the coming years. The Department's newly announced reform agenda will reshape how prekindergarten is managed. It's goal is to help inform the decisions the City must make to integrate an expanding prekindergarten program into Children…

  20. Expanding the taxonomy of the diagnostic criteria for temporomandibular disorders.

    PubMed

    Peck, C C; Goulet, J-P; Lobbezoo, F; Schiffman, E L; Alstergren, P; Anderson, G C; de Leeuw, R; Jensen, R; Michelotti, A; Ohrbach, R; Petersson, A; List, T

    2014-01-01

    There is a need to expand the current temporomandibular disorders' (TMDs) classification to include less common but clinically important disorders. The immediate aim was to develop a consensus-based classification system and associated diagnostic criteria that have clinical and research utility for less common TMDs. The long-term aim was to establish a foundation, vis-à-vis this classification system, that will stimulate data collection, validity testing and further criteria refinement. A working group [members of the International RDC/TMD Consortium Network of the International Association for Dental Research (IADR), members of the Orofacial Pain Special Interest Group (SIG) of the International Association for the Study of Pain (IASP), and members from other professional societies] reviewed disorders for inclusion based on clinical significance, the availability of plausible diagnostic criteria and the ability to operationalise and study the criteria. The disorders were derived from the literature when possible and based on expert opinion as necessary. The expanded TMDs taxonomy was presented for feedback at international meetings. Of 56 disorders considered, 37 were included in the expanded taxonomy and were placed into the following four categories: temporomandibular joint disorders, masticatory muscle disorders, headache disorders and disorders affecting associated structures. Those excluded were extremely uncommon, lacking operationalised diagnostic criteria, not clearly related to TMDs, or not sufficiently distinct from disorders already included within the taxonomy. The expanded TMDs taxonomy offers an integrated approach to clinical diagnosis and provides a framework for further research to operationalise and test the proposed taxonomy and diagnostic criteria.

  1. Similarity modeling on an expanded mesh applied to rotating turbulence

    NASA Astrophysics Data System (ADS)

    Domaradzki, J. Andrzej; Horiuti, Kiyosi

    2001-11-01

    Because of the reduction in the turbulent kinetic energy decay rates rotating turbulence presents a significant challenge for turbulence models developed for nonrotating cases. We show that the modeling difficulties are removed if the generalized similarity methods are implemented on an expanded mesh.

  2. Expanding Doctoral Education in South Africa: Pipeline or Pipedream?

    ERIC Educational Resources Information Center

    Herman, Chaya

    2011-01-01

    The purpose of this paper is to discuss both the status of the PhD in South Africa and the feasibility of the country's aspiration to increase by fivefold the production of PhDs by 2025. Based on the first empirical studies on doctoral education in South Africa, it argues that in order to move towards this target, an expanded and coordinated…

  3. Expanding Possibilities through Metaphor: Breaking Biases to Improve Crisis Management

    ERIC Educational Resources Information Center

    Cirka, Carol C.; Corrigall, Elizabeth A.

    2010-01-01

    In this article, we demonstrate that an exercise using metaphors to overcome cognitive biases helped students to proactively imagine and prepare for an expanded set of potential crises. The exercise complements traditional textbook approaches to crisis management and incorporates creativity skill building in a realistic context. Learning outcomes…

  4. Understanding Expanded School Mental Health Services in Baltimore City

    ERIC Educational Resources Information Center

    Walrath, Christine M.; Bruns, Eric J.; Anderson, Karyn L.; Glass-Siegal, Marcia; Weist, Mark D.

    2004-01-01

    This article explores the nature of expanded school mental health (ESMH) services in Baltimore City, which at the time of the study were incorporated into 40% of the citys public schools. A provider survey was distributed to ESMH clinicians to gather information on the characteristics of service providers and recipients, types of services being…

  5. Diaspora, Migration, and Globalization: Expanding the Discourse of Adult Education

    ERIC Educational Resources Information Center

    Alfred, Mary V.

    2015-01-01

    This article explores how notions of diaspora, migration, and globalization intersect to inform identities and social realities of those who leave their homeland and resettle in other nations. It calls for expanding the discourse of adult education to incorporate critical studies of the diaspora to make visible the inequality and imbalance of…

  6. Cantilever springs maintain tension in thermally expanded wires

    NASA Technical Reports Server (NTRS)

    Terselic, R. A.

    1965-01-01

    Two deflected cantilever springs strung with wire provide force displacement compensation to maintain tension in the wires as they undergo thermal expansion. This method of maintaining tension in thermally expanded wires is used in electric space heaters and residential heat exchangers.

  7. Browsing Your Virtual Library: The Case of Expanding Universe.

    ERIC Educational Resources Information Center

    Daniels, Wayne; Enright, Jeanne; Mackenzie, Scott

    1997-01-01

    Describes "Expanding Universe: a classified search tool for amateur astronomy," a Web site maintained by the Metropolitan Toronto Reference Library which uses a modified form of the Dewey Decimal Classification to organize a large file of astronomy hotlinks. Highlights include structure, HTML coding, design requirements, and future possibilities.…

  8. Expanding the Vision of Self: Why the Arts Matter

    ERIC Educational Resources Information Center

    Nathan, Linda F.

    2013-01-01

    In this reflective essay, Linda F. Nathan, the founding headmaster of the Boston Arts Academy and currently the executive director of Center for Arts in Education at Boston Arts Academy, shares a story about how one student, Ronald, expands his vision of self through his engagement with the arts. In presenting this reflection on Ronald's…

  9. Expanding Distribution of Lethal Amphibian Fungus Batrachochytrium salamandrivorans in Europe

    PubMed Central

    Spitzen-van der Sluijs, Annemarieke; Martel, An; Asselberghs, Johan; Bales, Emma K.; Beukema, Wouter; Bletz, Molly C.; Dalbeck, Lutz; Goverse, Edo; Kerres, Alexander; Kinet, Thierry; Kirst, Kai; Laudelout, Arnaud; Marin da Fonte, Luis F.; Nöllert, Andreas; Ohlhoff, Dagmar; Sabino-Pinto, Joana; Schmidt, Benedikt R.; Speybroeck, Jeroen; Spikmans, Frank; Steinfartz, Sebastian; Veith, Michael; Vences, Miguel; Wagner, Norman; Pasmans, Frank

    2016-01-01

    Emerging fungal diseases can drive amphibian species to local extinction. During 2010–2016, we examined 1,921 urodeles in 3 European countries. Presence of the chytrid fungus Batrachochytrium salamandrivorans at new locations and in urodeles of different species expands the known geographic and host range of the fungus and underpins its imminent threat to biodiversity. PMID:27070102

  10. A case of neonatal Jeune syndrome expanding the phenotype

    PubMed Central

    Drera, Bruno; Ferrari, Daniela; Cavalli, Pietro; Poggiani, Carlo

    2014-01-01

    Key Clinical Message We report the case of a premature, very low birth weight, newborn with stigmata of Jeune syndrome, a rare skeletal dysplasia, and marked renal involvement (i.e. remarkable prenatal oligohydramnios, histologic nephronophthisis-like pattern, macroscopic renal cysts, and renal failure), expanding the phenotype consistent with the continuum of syndromic ciliopathies. PMID:25356276

  11. Expanding Distribution of Lethal Amphibian Fungus Batrachochytrium salamandrivorans in Europe.

    PubMed

    Spitzen-van der Sluijs, Annemarieke; Martel, An; Asselberghs, Johan; Bales, Emma K; Beukema, Wouter; Bletz, Molly C; Dalbeck, Lutz; Goverse, Edo; Kerres, Alexander; Kinet, Thierry; Kirst, Kai; Laudelout, Arnaud; Marin da Fonte, Luis F; Nöllert, Andreas; Ohlhoff, Dagmar; Sabino-Pinto, Joana; Schmidt, Benedikt R; Speybroeck, Jeroen; Spikmans, Frank; Steinfartz, Sebastian; Veith, Michael; Vences, Miguel; Wagner, Norman; Pasmans, Frank; Lötters, Stefan

    2016-07-01

    Emerging fungal diseases can drive amphibian species to local extinction. During 2010-2016, we examined 1,921 urodeles in 3 European countries. Presence of the chytrid fungus Batrachochytrium salamandrivorans at new locations and in urodeles of different species expands the known geographic and host range of the fungus and underpins its imminent threat to biodiversity. PMID:27070102

  12. Expanding the Spanish Classroom: The "Art" in Liberal Arts

    ERIC Educational Resources Information Center

    Díaz, Erin M.

    2016-01-01

    Supplementing the foreign language curriculum with the incorporation of art museum visits has benefits for students, faculty, the campus art gallery, and the institution. Such a collaborative program serves to expand the classroom and complement instruction by providing learners with a new space to engage in authentic practice in the target…

  13. DEMONSTRATION OF PACKAGING MATERIALS ALTERNATIVES TO EXPANDED POLYSTYRENE

    EPA Science Inventory

    This report represents the second demonstration of cleaner technologies to support the goals of the 33/50 Program under the EPA Cooperative Agreement No. CR-821848. The report presents assessment results of alternative packaging materials which could potentially replace expanded...

  14. Reflections on Using Blogs to Expand In-Class Discussion

    ERIC Educational Resources Information Center

    Wang, Shiang-Kwei; Hsua, Hui-Yin

    2008-01-01

    Originally, blogs served as personal journaling tools. Recently, blogs have facilitated the formation of online communities and have thus expanded to more extensive uses in education. Little has been learned about using blogs as a collaboration tool in educational contexts. In this article, the authors share their experiences with using blogs to…

  15. Building an Expanded Learning Time and Opportunities School: Principals' Perspectives

    ERIC Educational Resources Information Center

    Malone, Helen Janc

    2011-01-01

    Expanded learning time and opportunities (ELTO) requires a committed school leader who is willing to partner with community-based organizations in order to provide strong academic and enrichment daily experiences for his or her students. This article examines four such leaders and the diverse approaches they took to implement ELTO in their…

  16. Expanding Literacies: Teachers' Inquiry Research and Multigenre Texts

    ERIC Educational Resources Information Center

    Simon, Lisa

    2007-01-01

    This article describes the results of an inquiry/multigenre project undertaken by students in a literacy foundations course. The project's initial pedagogical goal was to provide pre- and in-service teachers with multiple and engaging opportunities to read and write in areas of their interests. That goal expanded to encompass the critical literacy…

  17. Matching Students to Opportunity: Expanding College Choice, Access, and Quality

    ERIC Educational Resources Information Center

    Kelly, Andrew P., Ed.; Howell, Jessica S., Ed.; Sattin-Bajaj, Carolyn, Ed.

    2016-01-01

    "Matching Students to Opportunity" expands on the discussion of a critical issue in college access and success: the match between prospective students and the colleges in which they enroll. Research indicates that ensuring a good match significantly increases a student's chance of graduating. The contributors to this volume argue that…

  18. Program Performance 1971 Expanded Food and Nutrition Program.

    ERIC Educational Resources Information Center

    Extension Service (USDA), Washington, DC.

    General conclusions and recommendations resulting from a second in-depth evaluation of the Expanded Food and Nutrition Education Program of the Cooperative Extension Service, conducted 1 April 1970 through 31 March 1971, are presented. Evaluation data were collected from Extension personnel associated with the program and from local and state…

  19. An Expanded Framework for Analyzing General Chemistry Exams

    ERIC Educational Resources Information Center

    Smith, K. Christopher; Nakhleh, Mary B.; Bretz, Stacey Lowery

    2010-01-01

    This paper describes an expanded framework to aid chemical educators in constructing exams for their courses. The framework has three primary levels: definition, algorithmic, and conceptual. These primary levels have often been used in chemical education research to analyze and describe exam questions, but in this study the definition,…

  20. Spreading of ultrarelativistically expanding shell: An application to GRBs

    NASA Astrophysics Data System (ADS)

    Ruffini, R.; Siutsou, I. A.; Vereshchagin, G. V.

    2014-02-01

    Optically thick energy dominated plasma created in the source of Gamma-Ray Bursts (GRBs) expands radially with acceleration and forms a shell with constant width measured in the laboratory frame. When strong Lorentz factor gradients are present within the shell it is supposed to spread at sufficiently large radii. There are two possible mechanisms of spreading: hydrodynamical and thermal ones. We consider both mechanisms evaluating the amount of spreading that occurs during expansion up to the moment when the expanding shell becomes transparent for photons. We compute the hydrodynamical spreading of an ultrarelativistically expanding shell. In the case of thermal spreading we compute the velocity spread as a function of two parameters: comoving temperature and bulk Lorentz factor of relativistic Maxwellian distribution. Based on this result we determine the value of thermal spreading of relativistically expanding shell. We found that thermal spreading is negligible for typical GRB parameters. Instead hydrodynamical spreading appears to be significant, with the shell width reaching ˜1010 cm for total energy E=1054 erg and baryonic loading B=10-2. Within the fireshell model such spreading will result in the duration of Proper Gamma-Ray Bursts up to several seconds.

  1. Views of Nonprint Media: A Case for Expanded Literacy.

    ERIC Educational Resources Information Center

    Ruth, Deborah Dashow

    The process of becoming literate today means both visual and verbal literacy. There is no need, however, to choose between print and nonprint media as teaching tools. Today's "new media" serve to expand and accentuate the world of printed words and provide valuable means of learning in and of themselves. Visual literacy implies developing an…

  2. Expanding the Knowledge Base: A Rejoinder to Townsend (1998).

    ERIC Educational Resources Information Center

    Brent, Brian O.

    1998-01-01

    Provides a further examination of nonresidential expanded tax base (ETB) approaches to school finance. Disagrees with Townsend's optimism that more equitable distribution formulas can be found in existing state aid systems, and with Townsend's concern that the specification of distribution formulas will be subject to political manipulation.…

  3. Validation of the Chinese Expanded Euthanasia Attitude Scale

    ERIC Educational Resources Information Center

    Chong, Alice Ming-Lin; Fok, Shiu-Yeu

    2013-01-01

    This article reports the validation of the Chinese version of an expanded 31-item Euthanasia Attitude Scale. A 4-stage validation process included a pilot survey of 119 college students and a randomized household survey with 618 adults in Hong Kong. Confirmatory factor analysis confirmed a 4-factor structure of the scale, which can therefore be…

  4. The Instructional Values of Humanistic Educators: An Expanded, Empirical Analysis.

    ERIC Educational Resources Information Center

    Shapiro, Stewart B.

    1987-01-01

    Expanded a previous factorial study of the writings of 40 humanistic educators by including 89 educators. Revealed two new factors--self-determined evaluation and a spiritual-transpersonal factor--as important principles of humanistic education. Confirmed the original factors, a general humanistic instructional paradigm, democratically induced…

  5. Expanding Library Support of Faculty Research: Exploring Readiness

    ERIC Educational Resources Information Center

    Brown, Jeanne M.; Tucker, Cory

    2013-01-01

    The changing research and information environment requires a reexamination of library support for research. This study considers research-related attitudes and practices to identify elements indicating readiness or resistance to expanding the library's role in research support. A survey of faculty conducted at the University of Nevada Las…

  6. Targeting Expanded Care to the Aged: Early SHMO Experience.

    ERIC Educational Resources Information Center

    Leutz, Walter; And Others

    1988-01-01

    Describes targeting policies of four Social Health Maintenance Organization sites which deliver integrated, prepaid, acute, and chronic care to Medicare beneficiaries. Analyzes complexities of operationalizing targeting systems in four different settings. Notes that selection criteria for targeting expanded benefits and their implementation affect…

  7. Expanding Perspectives for Comprehending Visual Images in Multimodal Texts

    ERIC Educational Resources Information Center

    Serafini, Frank

    2011-01-01

    The texts that adolescents encounter today are often multimodal, meaning they incorporate a variety of modes, including visual images, hypertext, and graphic design elements along with written text. Expanding the perspectives readers use to make sense of the multimodal texts is an important aspect of comprehension instruction. Moving beyond the…

  8. Leakage Flow Characteristics in Expander for CO2 Refrigeration Cycle

    NASA Astrophysics Data System (ADS)

    Fukuta, Mitsuhiro; Adachi, Masaaki; Yanagisawa, Tadashi; Ogi, Yasuhiro

    Carbon dioxide (CO2) is considered to be an alternative to HFC refrigerants due to its non-flammability, non-toxicity and small global warming potential. To improve the performance of the CO2 refrigeration cycle, using an expander as an expansion device to recover a throttling loss has been examined. Since an inlet condition of the expander is supercritical and an exit is subcritical, leakage through a narrow clearance in the expander becomes a transcritical flow where the condition changes from the supercritical to the subcritical. It is necessary to clarify the characteristics of the transcritical leakage flow through the narrow clearance, because the leakage flow has serious influence on the expander performance. In this study, the transcritical leakage flow is modeled analytically and the flow characteristic is examined by the model. The calculated mass flow rate agrees with the experimental one. It is found that frictional loss accounts for a half of pressure drop both in the supercritical and two phase region at any inlet temperature tested in this study. In addition, the sealing effect of oil on the transcritical leakage flow rate is shown to be little.

  9. 2010 Impacts: The Expanded Food and Nutrition Education Program (EFNEP)

    ERIC Educational Resources Information Center

    National Institute of Food and Agriculture, 2011

    2011-01-01

    Since 1969, the Expanded Food and Nutrition Education Program (EFNEP) has improved the diets and food-related behaviors of program participants. Each year EFNEP enrolls more than half a million new program participants. In 2010, EFNEP reached 137,814 adults and 463,530 youth directly and nearly 400,000 family members indirectly. This paper…

  10. Studies of an expanded trinucleotide repeat in transgenic mice

    SciTech Connect

    Bingham, P.; Wang, S.; Merry, D.

    1994-09-01

    Spinal and bulbar muscular atrophy (SBMA) is a progressive motor neuron disease caused by expansion of a trinucleotide repeat in the androgen receptor gene (AR{sup exp}). AR{sup exp} repeats expand further or contract in approximately 25% of transmissions. Analogous {open_quotes}dynamic mutations{close_quotes} have been reported in other expanded trinucleotide repeat disorders. We have been developing a mouse model of this disease using a transgenic approach. Expression of the SBMA AR was documented in transgenic mice with an inducible promoter. No phenotypic effects of transgene expression were observed. We have extended our previous results on stability of the expanded trinucleotide repeat in transgenic mice in two lines carrying AR{sup exp}. Tail DNA was amplified by PCR using primers spanning the repeat on 60 AR{sup exp} transgenic mice from four different transgenic lines. Migration of the PCR product through an acrylamide gel showed no change of the 45 CAG repeat length in any progeny. Similarly, PCR products from 23 normal repeat transgenics showed no change from the repeat length of the original construct. Unlike the disease allele in humans, the expanded repeat AR cDNA in transgenic mice showed no change in repeat length with transmission. The relative stability of CAG repeats seen in the transgenic mice may indicate either differences in the fidelity of replicative enzymes, or differences in error identification and repair between mice and humans. Integration site or structural properties of the transgene itself might also play a role.

  11. Food for Thought: Expanding School Breakfast to NJ Students

    ERIC Educational Resources Information Center

    Allen-Kyle, Portia; Parello, Nancy

    2011-01-01

    This brief marks the start of "Advocates for Children of New Jersey's Food for Thought School Breakfast Campaign", which seeks to expand innovative approaches to serving school breakfast and significantly increase students' participation rates. This report provides a closer look at the data, including identifying districts that have high…

  12. Expanding Access to Adult Literacy with Online Distance Education.

    ERIC Educational Resources Information Center

    Askov, Eunice N.; Johnston, Jerome; Petty, Leslie I.; Young, Shannon J.

    This monograph examines benefits, challenges, and methods of expanding access to adult literacy with online distance education (ODE). The following are among the topics discussed: (1) reasons for considering ODE (new technologies and delivery systems in education; ODE in higher education, business training, and adult basic education; state-level…

  13. Expanding the Role of Connectionism in SLA Theory

    ERIC Educational Resources Information Center

    Language Learning, 2013

    2013-01-01

    In this article, I explore how connectionism might expand its role in second language acquisition (SLA) theory by showing how some symbolic models of bilingual and second language lexical memory can be reduced to a biologically realistic (i.e., neurally plausible) connectionist model. This integration or hybridization of the two models follows the…

  14. An Expanded Model of Faculty Vitality in Academic Medicine

    ERIC Educational Resources Information Center

    Dankoski, Mary E.; Palmer, Megan M.; Laird, Thomas F. Nelson; Ribera, Amy K.; Bogdewic, Stephen P.

    2012-01-01

    Many faculty in today's academic medical centers face high levels of stress and low career satisfaction. Understanding faculty vitality is critically important for the health of our academic medical centers, yet the concept is ill-defined and lacking a comprehensive model. Expanding on previous research that examines vital faculty in higher…

  15. Expanding Learning Opportunities for High School Students with Distance Learning

    ERIC Educational Resources Information Center

    Beese, Jane

    2014-01-01

    The purpose of the Synchronous Interactive Video Conference Distance Learning pilot program was to use emerging technologies to expand learning opportunities for students at an urban public high school. Through grant funding, students were able to enroll in Advanced Placement and foreign language courses through an online learning provider. Using…

  16. Apprenticeship Programs Expand with Help of Community Colleges

    ERIC Educational Resources Information Center

    Gonzalez, Jennifer

    2011-01-01

    The apprenticeship system, long considered an educational relic by some educators and policy makers, is gaining new attention as a model for improving job skills and meeting national college-completion goals. A number of states and community and technical colleges are working to strengthen and expand apprenticeship opportunities. They offer…

  17. Reducing Dropout Rates through Expanded Learning Opportunities. Issue Brief

    ERIC Educational Resources Information Center

    Harris, Laura; Princiotta, Daniel

    2009-01-01

    Expanded learning opportunities (ELOs), which include afterschool, summer learning, and extended day and extended year programs, can help states reduce dropout rates and increase graduation rates. Effective elementary, middle, and high school ELOs support academic rigor, boost student engagement, and provide students with supportive relationships.…

  18. Analysis of nitrogen condensation in an expanding nozzle flow

    NASA Technical Reports Server (NTRS)

    Wang, F. C.

    1976-01-01

    Condensation of nitrogen flow in an expanding nozzle flow is analyzed using one-dimensional gas dynamic equations and the equations for nucleation and droplet growth. Effects of variations in the Tolman constant and the mass accommodation factor are discussed as well as the effect of foreign nuclei. Comparisons are made with experimental data obtained from a small, contoured nozzle.

  19. Expanding the Definition of Privilege: The Concept of Social Privilege

    ERIC Educational Resources Information Center

    Black, Linda L.; Stone, David

    2005-01-01

    Examinations of privilege have historically focused on gender and race. By placing privilege within the context of oppression, the authors offer an expanded view of the domains of privilege that include sexual orientation, socioeconomic status, age, differing degrees of ableness, and religious affiliation.

  20. [Methodological aspects of expanded operations in patients with lung cancer].

    PubMed

    Lomidze, Z T; Gagua, R O; Kuchava, V O; Gzirishvili, L G

    2009-02-01

    In attempt to improve the results of treatment of locally advanced lung cancer different techniques are presented and described. In 1995-2008 in Thoracal Department of Georgian National Oncological Center lung resection was performed to 2460 patients, to 1368 (55,6%) of which expanded operations were performed. There were 1070 (78,2%) male and 298(21,8%) female. Expanded operations on the right side as well as on the left side were performed in cases when metastatic lesion of mediastinal lymphatic nodes was observed. Sometimes intrasurgical biopsy of lymphatic nodes with urgent histological examination was used to verify metastases of lymphatic nodes of mediastinum. One stage removal of lymphatic nodes with lung or parts of lungs was performed. Mobilization of cellular tissues and lymphatic nodes mediastinum is described. It was accompanied by careful electrocoagulation which provides at some degree the ablasticity of interference. Expanded pneumactomies on the right and on the left sides technically had several distinctions which were defined by the anatomical peculiarities of the right and left hemithorax. For the purpose of one stage removal of paratracheal and tracheobronchial lymphatic nodes, the azygos vien was ligated in all cases of the right side expanded pneumactomy. To get the better approach to tracheobronchial lymphatic nodes in left side expanded pneumactomies, arterial duct and bronchial arteries were ligated in several cases. The removal of paraaortal lymphatic nodes on posterolateral wall of aorta in several cases, due to their site, forced us to legate some intercostals arteries in all cases, when it was possible. We tried to preserve the integrity of large nerve trunks. PMID:19276465

  1. The Expanding Polity: Theorizing the Links between Expanded Higher Education and the New Politics of the Post-1970s

    ERIC Educational Resources Information Center

    Kamens, David H.

    2009-01-01

    In this article, I argue that the expansion of higher education worldwide has had important effects in restructuring the political system of affluent democracies. A large literature has developed that describes how democracy has been "downsized" (e.g., lower voting rates). This, I argue, is one impact of expanded higher education. But there is…

  2. Opportunities for synthetic biology in antibiotics: expanding glycopeptide chemical diversity.

    PubMed

    Thaker, Maulik N; Wright, Gerard D

    2015-03-20

    Synthetic biology offers a new path for the exploitation and improvement of natural products to address the growing crisis in antibiotic resistance. All antibiotics in clinical use are facing eventual obsolesce as a result of the evolution and dissemination of resistance mechanisms, yet there are few new drug leads forthcoming from the pharmaceutical sector. Natural products of microbial origin have proven over the past 70 years to be the wellspring of antimicrobial drugs. Harnessing synthetic biology thinking and strategies can provide new molecules and expand chemical diversity of known antibiotic scaffolds to provide much needed new drug leads. The glycopeptide antibiotics offer paradigmatic scaffolds suitable for such an approach. We review these strategies here using the glycopeptides as an example and demonstrate how synthetic biology can expand antibiotic chemical diversity to help address the growing resistance crisis.

  3. Basic Study on Engine with Scroll Compressor and Expander

    NASA Astrophysics Data System (ADS)

    Morishita, Etsuo; Kitora, Yoshihisa; Nishida, Mitsuhiro

    Scroll compressors are becoming popular in air conditioning and refrigeration. This is primarily due to their higher efficiency and low noise/vibration characteristics. The scroll principle can be applied also to the steam expander and the Brayton cycle engine,as shown in the past literature. The Otto cycle spark-ignition engine with a scroll compressor and expander is studied in this report. The principle and basic structure of the scroll engine are explained,and the engine characteristic are calculated based on the idealized cycles and processes. A prototype model has been proposed and constructed. The rotary type engine has always had a problem with sealing. The scroll engine might overcome this shortcoming with its much lower rubbing speed compared to its previous counterparts,and is therefore worth investigating.

  4. Einstein's conversion from his static to an expanding universe

    NASA Astrophysics Data System (ADS)

    Nussbaumer, Harry

    2014-02-01

    In 1917 Einstein initiated modern cosmology by postulating, based on general relativity, a homogenous, static, spatially curved universe. To counteract gravitational contraction he introduced the cosmological constant. In 1922 Alexander Friedman showed that Albert Einstein's fundamental equations also allow dynamical worlds, and in 1927 Georges Lemaître, backed by observational evidence, concluded that our universe was expanding. Einstein impetuously rejected Friedman's as well as Lemaître's findings. However, in 1931 he retracted his former static model in favour of a dynamic solution. This investigation follows Einstein on his hesitating path from a static to the expanding universe. Contrary to an often advocated belief the primary motive for his switch was not observational evidence, but the realisation that his static model was unstable.

  5. Design of Modern Reactors for Synthesis of Thermally Expanded Graphite.

    PubMed

    Strativnov, Eugene V

    2015-12-01

    One of the most progressive trends in the development of modern science and technology is the creation of energy-efficient technologies for the synthesis of nanomaterials. Nanolayered graphite (thermally exfoliated graphite) is one of the key important nanomaterials of carbon origin. Due to its unique properties (chemical and thermal stability, ability to form without a binder, elasticity, etc.), it can be used as an effective absorber of organic substances and a material for seal manufacturing for such important industries as gas transportation and automobile. Thermally expanded graphite is a promising material for the hydrogen and nuclear energy industries. The development of thermally expanded graphite production is resisted by high specific energy consumption during its manufacturing and by some technological difficulties. Therefore, the creation of energy-efficient technology for its production is very promising.

  6. REDSHIFTS AND THE EXPANDING UNIVERSE - PARADIGM SHIFT OR SLOW DAWNING?

    NASA Astrophysics Data System (ADS)

    Raifeartaigh, Cormac O.

    2014-01-01

    The observation by Edwin Hubble of a linear relation between the redshift of the spiral nebulae and their radial distance marked one of the great discoveries of 20th century astronomy. This paper examines how the finding was interpreted as possible evidence for a universe of expanding radius by a number of theoreticians, but not astronomers. A brief review of the cosmic models of theoreticians such as Lemaître, Eddington, Einstein, de Sitter and Tolman is given, contrasting their different views of issues such as spatial curvature, the cosmological constant, the singularity and the formation of structure. It is argued that the concept of an expanding universe was not fully accepted for many years, and is best seen as the slow dawning of an idea rather than an abrupt Kuhnian paradigm shift.

  7. Expanding Medicaid managed care: the right choice for Texas?

    PubMed

    Reddy, Swapna; Finley, Marisa; Posey, Dan; Rohack, James J

    2012-10-01

    We set out to determine whether expanding Medicaid managed care in Texas is the solution to the challenges faced by the state of meeting the healthcare needs of a rapidly growing Medicaid population while addressing its own fiscal limitations. We reviewed the Texas Medicaid program, the potential effects of federal healthcare reform, and the state political climate through the perspectives (advantages and disadvantages) of the primary stakeholders: patients, practitioners, hospitals, and insurers. Research was performed through online, federal and state regulatory, and legislative review. In addition, we reviewed government and peer-reviewed reports and articles pertaining to issues related to Medicaid populations, healthcare practitioners, and hospitals that serve them. Each primary stakeholder had potential advantages and disadvantages associated with the expansion of Medicaid managed care. We conclude that expanding Medicaid managed care, if done in a manner responsive to the needs of recipients, can meet enrollees' healthcare needs while controlling the state's costs.

  8. Internally folded expanded metal electrode for battery construction

    NASA Technical Reports Server (NTRS)

    Korinek, Paul D. (Inventor); Morgan, Maurice C. (Inventor); Pierce, Doug C. (Inventor)

    1993-01-01

    A battery system is disclosed which includes folded grids of expanded metal inserted through non-conductive substrates and pasted with electrochemically active materials. In the most preferred embodiment, a frame is provided with a plastic insert, and slots are provided in the latter to receive the expanded metal grid. After suitable coinage of the grid and insertion through the plastic film, the grid is sealed and pasted on opposite sides with positive and negative active material. A battery is assembled using one or a plurality of the resulting electrode elements, with separators, to produce a high-power, lead-acid battery. The folded grid provides many of the design benefits of standard bipolar construction.

  9. Small-angle neutron scattering from samples of expanded carbon

    SciTech Connect

    Bogdanov, S. G. Valiev, E. Z.; Dorofeev, Yu. A.; Pirogov, A. N.; Skryabin, Yu. N.; Makotchenko, V. G.; Nazarov, A. S.; Fedorov, V. E.

    2006-12-15

    The subatomic structure of expanded graphite has been investigated by small-angle neutron scattering. Samples were synthesized during quick thermal decomposition of intercalated compounds based on oxidized graphite. They had a low bulk density (up to 0.1 g/cm{sup 3}) and were characterized by considerable small-angle scattering. It has been established that majority of the volume of expanded graphite samples is occupied by participles with characteristic sizes in two ranges: from 6 to 8 nm and from 20 to 30 nm. Small particles have properties of a surface fractal with the dimension D{sub s} = 2.4-2.6, whereas the larger particles are mainly smooth and have the dimension D{sub s} = 2.0-2.1. The specific surface of the samples studied was determined from the small-angle scattering data.

  10. Outflow Propagation in Collapsars: Collimated Jets And Expanding Outflows

    SciTech Connect

    Mizuta, A.; Yamasaki, T.; Nagataki, S.; Mineshige, S.; /Kyoto U., Yukawa Inst., Kyoto /KIPAC, Menlo Park

    2007-06-08

    We investigate the outflow propagation in the collapsar in the context of gamma-ray bursts (GRBs) with 2D relativistic hydrodynamic simulations. We vary the specific internal energy and bulk Lorentz factor of the injected outflow from non-relativistic regime to relativistic one, fixing the power of the outflow to be 10{sup 51}erg s{sup -1}. We observed the collimated outflow, when the Lorentz factor of the injected outflow is roughly greater than 2. To the contrary, when the velocity of the injected outflow is slower, the expanding outflow is observed. The transition from collimated jet to expanding outflow continuously occurs by decreasing the injected velocity. Different features of the dynamics of the outflows would cause the difference between the GRBs and similar phenomena, such as, X-ray flashes.

  11. Expanding Medicaid managed care: the right choice for Texas?

    PubMed

    Reddy, Swapna; Finley, Marisa; Posey, Dan; Rohack, James J

    2012-10-01

    We set out to determine whether expanding Medicaid managed care in Texas is the solution to the challenges faced by the state of meeting the healthcare needs of a rapidly growing Medicaid population while addressing its own fiscal limitations. We reviewed the Texas Medicaid program, the potential effects of federal healthcare reform, and the state political climate through the perspectives (advantages and disadvantages) of the primary stakeholders: patients, practitioners, hospitals, and insurers. Research was performed through online, federal and state regulatory, and legislative review. In addition, we reviewed government and peer-reviewed reports and articles pertaining to issues related to Medicaid populations, healthcare practitioners, and hospitals that serve them. Each primary stakeholder had potential advantages and disadvantages associated with the expansion of Medicaid managed care. We conclude that expanding Medicaid managed care, if done in a manner responsive to the needs of recipients, can meet enrollees' healthcare needs while controlling the state's costs. PMID:23038487

  12. Pascual Jordan, Varying Gravity, and the Expanding Earth

    NASA Astrophysics Data System (ADS)

    Kragh, Helge

    2015-06-01

    In the 1950s, surprising links were proposed between cosmological theory and the geological and paleontological sciences. These links were mainly provided by Paul Dirac's hypothesis of 1937 that the gravitational constant G decreases with cosmic time. Pascual Jordan, famous for his pioneering contributions to quantum theory, took up Dirac's hypothesis; after the end of World War II, Jordan developed its geophysical consequences, concluding that the Earth is expanding. Much of Jordan's later scientific work focused on the expanding Earth and other aspects of the earth sciences relating to the varying- G hypothesis. This chapter in the history of science has received almost no attention from either scientists or historians. The article analyzes Jordan's cosmo-geological work in relation to the somewhat similar efforts of other "expansionists" in the period that led to the plate tectonic revolution in the earth sciences.

  13. Expanded beam non-imaging fiber optic connector

    DOEpatents

    Jannson, Tommasz; Jannson, Joanna; Yeung, Peter

    1990-01-01

    There is disclosed an expanded beam fiber to fiber connector, based on non-imaging optic principles for coupling light beams from one optical fiber to another. The system consists of two identical connector parts, referred to herein as a collimating part and a concentrating part, each having a preferred partially curved reflective boundary surface for minimizing power loss and surrounding either a hollow space or a space filled with a uniform transparent medium. In one embodiment the boundary is metallic while in a second embodiment the boundary is in the form of an interface allowing total internal reflection. In both the hollow and filled case a lens may be located at the expanded end of both the collimater part and the concentrator part forming the connector. The connector is preferably located in a housing in order to protect and preserve the mechanical stability of the coupler.

  14. Culture and meaning: expanding the metaphorical repertoire of family therapy.

    PubMed

    Paré, D A

    1996-03-01

    This essay proposes that a family therapy founded on a contemporary, postmodern perspective demands an expanded range of metaphors for the family and the work of therapy. It describes a perspective that emphasizes a view of the family as a culture, as opposed to a system. A cultural perspective naturally addresses issues of meaning and language, narrative, politics, and practices of power-critical contemporary concerns not adequately encompassed by traditional systemic formulations. The essay explores the relationship between theory and metaphor, and contrasts the views of persons and of the family offered by the metaphors of culture and system. Case illustrations demonstrate how a cultural view effectively fashions an expanded therapeutic discourse, shifting the focus of family therapy from normative prescriptions for family "functionality" to issues of intercultural harmony. This shift in emphasis also extends to individual work, where the therapeutic task is construed as a peace-making between conflicting stories that intersect in the client's life. PMID:8804965

  15. Extrusion Simulation for Manufacturing Stabilization of Expandable Polymer

    NASA Astrophysics Data System (ADS)

    Son, Jae Hwan; Han, Chang Woo; Choi, Won Sik; Noh, Kyoo Ik; Kim, Young Suk; Lee, Young Moon

    This study investigates pressure and temperature changes in an extrusion die of expandable polymer according to resin flow. Depending on die design each three structural changes of the die neck width and lip height were assumed and the effects were analyzed. It is revealed that the maximum pressure decreases as the inlet width of die neck and outlet height of die lip increase. The mean temperature decreases as the inlet width increase, but it does not change with the outlet height.

  16. Development of Self-Expanding Idealflo (tm) Sandcontrol Technology

    SciTech Connect

    Jeff A. Spray

    2007-09-30

    Development of Self-Expanding Idealflo{trademark} Sandscreen Technology was a successfully executed design-by-analysis through field demonstration project. This final report is presented as a two-part progression of concept development and manufacturing activities. The first part, conceptual development activities, discusses novel specifications creation and non-linear analytical design generation. The second part, manufacturing, contains achievement related information for detailed-design, fabrication, mechanical testing, and field demonstration activities.

  17. Equilibrium states for random non-uniformly expanding maps

    NASA Astrophysics Data System (ADS)

    Arbieto, Alexander; Matheus, Carlos; Oliveira, Krerley

    2004-03-01

    We show that for a robust (C2-open) class of random non-uniformly expanding maps there exist equilibrium states for a large class of potentials. In particular, these sytems have measures of maximal entropy. These results also give a partial answer to a question posed by Liu-Zhao. The proof of the main result uses an extension of techniques in recent works by Alves-Araújo, Alves-Bonatti-Viana and Oliveira.

  18. Australia announces plans for expanded marine reserve network

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2012-06-01

    Australia announces plans for expanded marine reserve network The Australian government has announced plans to increase the nation's network of marine reserves from 27 to 60, bringing the total size of the network to 3.1 million square kilometers, Australia's environment minister Tony Burke said on 14 June. The expansion, which would place more than one third of Australia's waters under protection, requires a 60-day consultation before it can become law.

  19. Maintaining and Expanding the Hands-On Optics Program

    NASA Astrophysics Data System (ADS)

    Pompea, Stephen M.; Sparks, R. T.; Walker, C. E.

    2008-05-01

    Hands-On Optics (HOO) was funded by the National Science Foundation Informal Science Education program to bring optics education to traditionally underserved middle school students. We developed a series of six optics modules each covering a different topic in optics. During the four-year grant, we brought the program to the Mathematics, Science and Engineering Achievement (MESA) programs in seven states as well as 8 major science centers. We continue to support our established sites as well as expand our program. One of our expansion efforts involves continuing our partnership with the International Society for Optical Engineering (SPIE). We have been working closely with SPIE to present workshops for student chapter leaders at SPIE meetings. The student chapter leaders use HOO materials in their outreach activities. SPIE has teamed with us to bring HOO to Europe. We have received a grant from the Science Foundation of Arizona to expand HOO in Arizona. This program builds on our successful programs at the South Tucson Boys and Girls Club as well as the Sells Boys and Girls Club by expanding HOO to other sites around the state with an emphasis on rural locations such as Bisbee, Safford, Prescott Valley and the Tohon O'odham Nation. We have been working with a variety of Boys and Girls Clubs around the state. Several programs are underway and we hope to add more sites in the coming year. We continue to host local events at Kitt Peak National Observatory as well as special events for the community and students in the Tucson area. Our events include science nights at local schools, optics festivals and competitions, career days and teacher fairs. We will describe the current state of the program as well as lessons learned as we expand the program in a variety of settings.

  20. National Earthquake Hazards Reduction Program; time to expand

    USGS Publications Warehouse

    Steinbrugge, K.V.

    1990-01-01

    All of us in earthquake engineering, seismology, and many related disciplines have been directly or indirectly affected by the National Earthquake Hazards Reduction Program (NEHRP). This program was the result of the Earthquake Hazards Reduction Act of 1977 (Public Law 95-124). With well over a decade of experience, should this expression of public policy now take a different or expanded role? 

  1. The Hubble party balloon and the expanding universe

    NASA Astrophysics Data System (ADS)

    Zendri, G.; Rosi, T.; Oss, S.

    2016-09-01

    We show that the metaphor of the inflated balloon used to describe expanding space-time according to the Hubble law can be transformed into a simple laboratory experiment. We obtain, in terms of measured recession speeds and distances of ink dots drawn on a party balloon, easy renditions of various cosmological models, such as the static one and the Einstein-De Sitter universe.

  2. Hydroaminations of alkenes: a radical, revised, and expanded version.

    PubMed

    Villa, Matteo; Jacobi von Wangelin, Axel

    2015-10-01

    Radical changes: The applicability of alkene hydroamination has recently been significantly expanded by the development of radical variants that are based on initial hydrogen atom transfer to the alkene. This Highlight assesses the current state of the art, focusing on an iron-catalyzed reaction that utilizes stable nitroarenes as the electrophilic N component and is based on the dual catalytic activation of both starting materials.

  3. Tissue Expanders in Skin Deficient Ventral Hernias Utilizing Component Separation

    PubMed Central

    Molinar, Vanessa E.; Molinar, Alonso; Palladino, Humberto

    2015-01-01

    Summary: Skin deficient complex ventral hernias are complicated surgical cases that have multimodal approaches. There is no current consensus on the management of those patients who also have concomitant stomas or enterocutaneous fistula. We present 2 cases in which the senior authors were able to apply tissue expanders above and between the abdominal wall in patients with an enterocutaneous fistula or stoma. After expansion and final closure, the patients did not experience recurrent hernias. PMID:26893988

  4. Tissue Expanders in Skin Deficient Ventral Hernias Utilizing Component Separation.

    PubMed

    Agullo, Francisco J; Molinar, Vanessa E; Molinar, Alonso; Palladino, Humberto

    2015-11-01

    Skin deficient complex ventral hernias are complicated surgical cases that have multimodal approaches. There is no current consensus on the management of those patients who also have concomitant stomas or enterocutaneous fistula. We present 2 cases in which the senior authors were able to apply tissue expanders above and between the abdominal wall in patients with an enterocutaneous fistula or stoma. After expansion and final closure, the patients did not experience recurrent hernias. PMID:26893988

  5. Expanding the catalog of cas genes with metagenomes.

    PubMed

    Zhang, Quan; Doak, Thomas G; Ye, Yuzhen

    2014-02-01

    The CRISPR (clusters of regularly interspaced short palindromic repeats)-Cas adaptive immune system is an important defense system in bacteria, providing targeted defense against invasions of foreign nucleic acids. CRISPR-Cas systems consist of CRISPR loci and cas (CRISPR-associated) genes: sequence segments of invaders are incorporated into host genomes at CRISPR loci to generate specificity, while adjacent cas genes encode proteins that mediate the defense process. We pursued an integrated approach to identifying putative cas genes from genomes and metagenomes, combining similarity searches with genomic neighborhood analysis. Application of our approach to bacterial genomes and human microbiome datasets allowed us to significantly expand the collection of cas genes: the sequence space of the Cas9 family, the key player in the recently engineered RNA-guided platforms for genome editing in eukaryotes, is expanded by at least two-fold with metagenomic datasets. We found genes in cas loci encoding other functions, for example, toxins and antitoxins, confirming the recently discovered potential of coupling between adaptive immunity and the dormancy/suicide systems. We further identified 24 novel Cas families; one novel family contains 20 proteins, all identified from the human microbiome datasets, illustrating the importance of metagenomics projects in expanding the diversity of cas genes.

  6. Focusing of geodesic congruences in an accelerated expanding Universe

    SciTech Connect

    Albareti, F.D.; Cembranos, J.A.R.; Cruz-Dombriz, A. de la E-mail: cembra@fis.ucm.es

    2012-12-01

    We study the accelerated expansion of the Universe through its consequences on a congruence of geodesics. We make use of the Raychaudhuri equation which describes the evolution of the expansion rate for a congruence of timelike or null geodesics. In particular, we focus on the space-time geometry contribution to this equation. By straightforward calculation from the metric of a Robertson-Walker cosmological model, it follows that in an accelerated expanding Universe the space-time contribution to the Raychaudhuri equation is positive for the fundamental congruence, favoring a non-focusing of the congruence of geodesics. However, the accelerated expansion of the present Universe does not imply a tendency of the fundamental congruence to diverge. It is shown that this is in fact the case for certain congruences of timelike geodesics without vorticity. Therefore, the focusing of geodesics remains feasible in an accelerated expanding Universe. Furthermore, a negative contribution to the Raychaudhuri equation from space-time geometry which is usually interpreted as the manifestation of the attractive character of gravity is restored in an accelerated expanding Robertson-Walker space-time at high speeds.

  7. Porous expandable device for attachment to bone tissue

    DOEpatents

    Rybicki, Edmund F.; Wheeler, Kenneth Ray; Hulbert, Lewis E.; Karagianes, Manuel Tom; Hassler, Craig R.

    1977-01-01

    A device for attaching to substantially solid living bone tissue, comprising a body member having an outer surface shaped to fit approximately into an empty space in the tissue and having pores into which the tissue can grow to strengthen the bond between the device and the tissue, and adjustable means for expanding the body member against the tissue to an extent such as to provide a compressive stress capable of maintaining a snug and stable fit and of enhancing the growth of the tissue into the pores in the body member. The expanding means is adjustable to provide a stress between the tissue and the body member in the range of about 150 to 750 psi, typically 150 to 350 psi. Typically the body member comprises an expandable cylindrical portion having at least one radial slit extending longitudinally from a first end to the vicinity of the opposite (second) end thereof, at least one radial slit extending longitudinally from the second end to the vicinity of the first end thereof, and a tapered cylindrical hole extending coaxially from a wider circular opening in the first end to a narrower circular opening communicating with the second end.

  8. Stability of stagnation via an expanding accretion shock wave

    NASA Astrophysics Data System (ADS)

    Velikovich, A. L.; Murakami, M.; Taylor, B. D.; Giuliani, J. L.; Zalesak, S. T.; Iwamoto, Y.

    2016-05-01

    Stagnation of a cold plasma streaming to the center or axis of symmetry via an expanding accretion shock wave is ubiquitous in inertial confinement fusion (ICF) and high-energy-density plasma physics, the examples ranging from plasma flows in x-ray-generating Z pinches [Maron et al., Phys. Rev. Lett. 111, 035001 (2013)] to the experiments in support of the recently suggested concept of impact ignition in ICF [Azechi et al., Phys. Rev. Lett. 102, 235002 (2009); Murakami et al., Nucl. Fusion 54, 054007 (2014)]. Some experimental evidence indicates that stagnation via an expanding shock wave is stable, but its stability has never been studied theoretically. We present such analysis for the stagnation that does not involve a rarefaction wave behind the expanding shock front and is described by the classic ideal-gas Noh solution in spherical and cylindrical geometry. In either case, the stagnated flow has been demonstrated to be stable, initial perturbations exhibiting a power-law, oscillatory or monotonic, decay with time for all the eigenmodes. This conclusion has been supported by our simulations done both on a Cartesian grid and on a curvilinear grid in spherical coordinates. Dispersion equation determining the eigenvalues of the problem and explicit formulas for the eigenfunction profiles corresponding to these eigenvalues are presented, making it possible to use the theory for hydrocode verification in two and three dimensions.

  9. Polypropylenes foam consisting of thermally expandable microcapsule as blowing agent

    NASA Astrophysics Data System (ADS)

    Jeoung, Sun Kyung; Hwang, Ye Jin; Lee, Hyun Wook; Kwak, Sung Bok; Han, In-Soo; Ha, Jin Uk

    2016-03-01

    The structure of thermally expandable microcapsule (TEMs) is consisted of a thermoplastic shell which is filled with liquid hydrocarbon at core. The shell of TEMs becomes soft when the temperature is higher than boiling temperature of liquid hydrocarbon. The shell of TEMs is expanded under the high temperature because the inner pressure of TEMs is increased by vaporization of hydrocarbon core. Therefore, the TEMs are applicable for blowing agents and light weight fillers. In this research, we fabricated the polypropylene (PP) foam by using the TEMs and chemical blowing agents and compared to their physical properties. The density of the specimen was decreased when the contents of chemical blowing agents and TEMs were increased. In addition, the mechanical properties (i.e. tensile strength and impact strength) of specimens were deteriorated with increasing amount of chemical blowing agents and TEMs. However, PP foam produced with TEMs showed higher impact strength than the one with the chemical blowing agent. In order to clarify the dependence of impact strength of PP foam as the blowing agent, the morphology difference of the PP foams was investigated. Expanding properties of PP foams produced with TEMs was changed with TEMs content of PP foams. Processing conditions also influenced the mechanical properties of PP foam containing TEMs.

  10. Environmental Assessment Expanded Ponnequin Wind Energy Project Weld County, Colorado

    SciTech Connect

    N /A

    1999-03-02

    The U.S.Department of Energy (DOE) has considered a proposal from the State of Colorado, Office of Energy Conservation (OEC), for funding construction of the Expanded Ponnequin Wind Project in Weld County, Colorado. OEC plans to enter into a contracting arrangement with Public Service Company of Colorado (PSCO) for the completion of these activities. PSCo, along with its subcontractors and business partners, are jointly developing the Expanded Ponnequin Wind Project. DOE completed an environmental assessment of the original proposed project in August 1997. Since then, the geographic scope and the design of the project changed, necessitating additional review of the project under the National Environmental Policy Act. The project now calls for the possible construction of up to 48 wind turbines on State and private lands. PSCo and its partners have initiated construction of the project on private land in Weld County, Colorado. A substation, access road and some wind turbines have been installed. However, to date, DOE has not provided any funding for these activities. DOE, through its Commercialization Ventures Program, has solicited applications for financial assistance from state energy offices, in a teaming arrangement with private-sector organizations, for projects that will accelerate the commercialization of emerging renewable energy technologies. The Commercialization Ventures Program was established by the Renewable Energy and Energy Efficiency Technology Competitiveness Act of 1989 (P.L. 101-218) as amended by the Energy Policy Act of 1992 (P.L. 102-486). The Program seeks to assist entry into the marketplace of newly emerging renewable energy technologies, or of innovative applications of existing technologies. In short, an emerging renewable energy technology is one which has already proven viable but which has had little or no operational experience. The Program is managed by the Department of Energy, Office of Energy Efficiency and Renewable Energy. The

  11. Expanding relativistic shells and gamma-ray burst temporal structure

    SciTech Connect

    Fenimore, E.E.; Madras, C.D.; Nayakshin, S.

    1996-12-01

    Many models of gamma-ray bursts (GRBs) involve a shell expanding at extreme relativistic speeds. The shell of material expands in a photon-quiet phase for a period {ital t}{sub 0} and then becomes gamma-ray active, perhaps due to inhomogeneities in the interstellar medium or the generation of shocks. Based on kinematics, we relate the envelope of the emission of the event to the characteristics of the photon-quiet and photon-active phases. We initially assume local spherical symmetry wherein, on average, the same conditions prevail over the shell`s surface within angles the order of {Gamma}{sup {minus}1}, where {Gamma} is the Lorentz factor for the bulk motion. The contribution of the curvature to the temporal structure is comparable to the contribution from the overall expansion. As a result, GRB time histories from a shell should have an envelope similar to {open_quotes}FRED{close_quotes} (fast rise, exponential decay) events in which the rise time is related to the duration of the photon-active phase and the fall time is related to the duration of the photon-quiet phase. This result depends only on local spherical symmetry and, since most GRBs do not have such envelopes, we introduce the {open_quotes}shell symmetry{close_quotes} problem: the observed time history envelopes of most GRBs do not agree with that expected for a relativistic expanding shell. Although FREDs have the signature of a relativistic shell, they may not be due to a single shell, as required by some cosmological models. Some FREDs have precursors in which the peaks are separated by more than the expansion time required to explain FRED shape. Such a burst is most likely explained by a central engine; that is, the separation of the multiple peaks occurs because the central site produced multiple releases of energy on timescales comparable to the duration of the event. (Abstract Truncated)

  12. Emissions reductions from expanding state-level renewable portfolio standards.

    PubMed

    Johnson, Jeremiah X; Novacheck, Joshua

    2015-05-01

    In the United States, state-level Renewable Portfolio Standards (RPS) have served as key drivers for the development of new renewable energy. This research presents a method to evaluate emissions reductions and costs attributable to new or expanded RPS programs by integrating a comprehensive economic dispatch model and a renewable project selection model. The latter model minimizes incremental RPS costs, accounting for renewable power purchase agreements (PPAs), displaced generation and capacity costs, and net changes to a state's imports and exports. We test this method on potential expansions to Michigan's RPS, evaluating target renewable penetrations of 10% (business as usual or BAU), 20%, 25%, and 40%, with varying times to completion. Relative to the BAU case, these expanded RPS policies reduce the CO2 intensity of generation by 13%, 18%, and 33% by 2035, respectively. SO2 emissions intensity decreased by 13%, 20%, and 34% for each of the three scenarios, while NOx reductions totaled 12%, 17%, and 31%, relative to the BAU case. For CO2 and NOx, absolute reductions in emissions intensity were not as large due to an increasing trend in emissions intensity in the BAU case driven by load growth. Over the study period (2015 to 2035), the absolute CO2 emissions intensity increased by 1% in the 20% RPS case and decreased by 6% and 22% for the 25% and 40% cases, respectively. Between 26% and 31% of the CO2, SO2, and NOx emissions reductions attributable to the expanded RPS occur in neighboring states, underscoring the challenges quantifying local emissions reductions from state-level energy policies with an interconnected grid. Without federal subsidies, the cost of CO2 mitigation using an RPS in Michigan is between $28 and $34/t CO2 when RPS targets are met. The optimal renewable build plan is sensitive to the capacity credit for solar but insensitive to the value for wind power. PMID:25884101

  13. Statistical physics of topological emulsions and expanding populations

    NASA Astrophysics Data System (ADS)

    Korolev, Kirill Sergeevich

    This thesis studies how microscopic interactions lead to large scale phenomena in two very different systems: two-dimensional liquid crystals and expanding populations. First, we explore the interactions among circular droplets embedded in a two-dimensional liquid crystal. The interactions arise due to anchoring boundary conditions on the surface of the inclusions and the elastic deformations of the orientational order parameter in the continuous phase. We analytically compute the texture around a single droplet and the far-field droplet-droplet pair potential. The near-field pair potential is computed numerically. We find that droplets attract at long separations and repel at short separations, which results in a well-defined preferred distance between the droplets and stabilization of the emulsion. Self-organization, barriers to coalescence, and the effects of thermal fluctuations are also discussed. Second, we study the role of randomness in the number of offspring on the evolutionary dynamics of expanding populations. Several equally fit genetic variants (alleles) are considered. We find that spatial expansion combined with demographic fluctuations leads to a substantial loss of genetic diversity and spatial segregation of the alleles. The effects of these processes on recurring mutations and selective sweeps are studied as well. Third, the competition between two alleles of different fitness is investigated. We find that the essential features of this competition can be captured by a non-linear reaction-diffusion equation. During a range expansion the fitter allele forms growing sectors that eventually engulf the less fit allele. The applications to measuring relative fitness in microbiological experiments are discussed. Finally, we analyze how a combination of strong stochasticity and weak competition affects the spreading of beneficial mutations in stationary, non-expanding, populations.

  14. Emissions reductions from expanding state-level renewable portfolio standards.

    PubMed

    Johnson, Jeremiah X; Novacheck, Joshua

    2015-05-01

    In the United States, state-level Renewable Portfolio Standards (RPS) have served as key drivers for the development of new renewable energy. This research presents a method to evaluate emissions reductions and costs attributable to new or expanded RPS programs by integrating a comprehensive economic dispatch model and a renewable project selection model. The latter model minimizes incremental RPS costs, accounting for renewable power purchase agreements (PPAs), displaced generation and capacity costs, and net changes to a state's imports and exports. We test this method on potential expansions to Michigan's RPS, evaluating target renewable penetrations of 10% (business as usual or BAU), 20%, 25%, and 40%, with varying times to completion. Relative to the BAU case, these expanded RPS policies reduce the CO2 intensity of generation by 13%, 18%, and 33% by 2035, respectively. SO2 emissions intensity decreased by 13%, 20%, and 34% for each of the three scenarios, while NOx reductions totaled 12%, 17%, and 31%, relative to the BAU case. For CO2 and NOx, absolute reductions in emissions intensity were not as large due to an increasing trend in emissions intensity in the BAU case driven by load growth. Over the study period (2015 to 2035), the absolute CO2 emissions intensity increased by 1% in the 20% RPS case and decreased by 6% and 22% for the 25% and 40% cases, respectively. Between 26% and 31% of the CO2, SO2, and NOx emissions reductions attributable to the expanded RPS occur in neighboring states, underscoring the challenges quantifying local emissions reductions from state-level energy policies with an interconnected grid. Without federal subsidies, the cost of CO2 mitigation using an RPS in Michigan is between $28 and $34/t CO2 when RPS targets are met. The optimal renewable build plan is sensitive to the capacity credit for solar but insensitive to the value for wind power.

  15. Simple scheme for expanding photonic cluster states for quantum information

    SciTech Connect

    Kalasuwan, P.; Laing, A.; Coggins, J.; Callaway, M.; O'Brien, J. L.; Mendoza, G.; Nagata, T.; Takeuchi, S.; Stefanov, A.

    2010-06-15

    We show how an entangled cluster state encoded in the polarization of single photons can be straightforwardly expanded by deterministically entangling additional qubits encoded in the path degree of freedom of the constituent photons. This can be achieved using a polarization-path controlled-phase gate. We experimentally demonstrate a practical and stable realization of this approach by using a Sagnac interferometer to entangle a path qubit and polarization qubit on a single photon. We demonstrate precise control over phase of the path qubit to change the measurement basis and experimentally demonstrate properties of measurement-based quantum computing using a two-photon, three-qubit cluster state.

  16. Evaluated Rayleigh integrals for pulsed planar expanding ring sources

    SciTech Connect

    Warshaw, S.I.

    1985-12-20

    Time-domain analytic and semianalytic pressure fields acoustically radiated from expanding pulsed ring sources imbedded in a planar rigid baffle have been calculated. The source functions are radially symmetric delta-function distributions whose amplitude and argument have simple functional dependencies on radius and time. Certain cases yield closed analytic results, while others result in elliptic integrals, which are evaluated to high accuracy by Gauss-Chebyshev and modified Gauss-Legendre quadrature. These results are of value for calibrating computer simulations and convolution procedures, and estimating fields from more complex planar radiators. 3 refs., 4 figs.

  17. Study of an under-expanded sonic impinging jet array

    NASA Astrophysics Data System (ADS)

    Lee, Joon Ho

    The under-expanded impinging jet is used in various situations, such as the launch of a rocket, the takeoff and landing of a vertical/short take off and landing aircraft, jet engine exhaust impingement, or the thrust vector control system of a solid rocket motor. It is also of considerable interest to study the fluid dynamics of jet impingement on a surface with respect to heat transfer. Past investigations of sonic or supersonic impinging jets were limited to only a single jet and were primarily concentrated on fluid mechanics phenomena. No results exist in the literature for an under-expanded sonic impinging jet array. The present study is focused on the fluid dynamics for an array of under-expanded sonic impinging jets with the ultimate objective being to study the understanding of the interaction between impinging jets and the effect of jet-to-jet spacing (s/d), jet-to-plate spacing (z/d), and the degree of under-expansion (P0/Pa). Schlieren videography was applied to study the variation of structures that dominate the supersonic impinging flow, such as the intercepting shock, reflected shock, normal disk, stand-off-plate shock, and stagnation bubble. A high frequency transducer was used to measure the pressure field of the fluid flow near the impingement surface. Test configurations included non-dimensional jet-to-plate heights from 1 to 10, non-dimensional jet-to-jet spacing of 2 and 4, and pressure ratios from 3.3 to 12.9. Jets with orifice diameter of 12.7 and 25.4 mm were used. The fluid dynamics of an under-expanded sonic jet array differ largely from a single jet at s/d = 2. Midway between jets and near each stagnation bubble region, the jet array shows higher values in surface pressure due to the jet interaction. Both a single jet and a jet array have the linear dependence between z/d for the location of the shock cell and transition from supersonic wall jet to subsonic wall jet. However, the jet array show the location of the shock cell is changing

  18. Endoscopic palliation for pancreatic cancer with expandable metal stents.

    PubMed

    Spitz, J D; Arregui, M E

    2000-05-01

    Pancreatic cancer is generally not amenable to curative resection. Consequently, therapeutic efforts for these patients are most commonly directed at palliation of symptoms. Historically, surgery has been considered the most effective method of providing relief for biliary and/or enteric obstruction. However, less invasive methods have become available that can provide effective relief of jaundice and duodenal obstruction. Surgeons should still play an integral role in the management of these patients. We present a case report in which self-expanding metallic stents were used to relieve obstruction of the bile duct and duodenum in a patient with unresectable pancreatic cancer.

  19. Evaluation of expanded uncertainties in luminous intensity and illuminance calibrations

    SciTech Connect

    Sametoglu, Ferhat

    2008-11-01

    Detector-based calibrating methods and expressions for calculation of photometric uncertainties related to uncertainties in the calibrations of luminous intensity of a light source, illuminance responsivity of a photometer head, and calibration factors of an illuminance meter are discussed. These methods permit luminous intensity calibrations of incandescent light sources, luminous responsivity calibrations of photometer heads, and calibration factors of illuminance meters to be carried out with relative expanded uncertainties (with a level of confidence of 95.45%) of 0.4%, 0.4%, and 0.6%, respectively.

  20. Evaluation of expanded uncertainties in luminous intensity and illuminance calibrations.

    PubMed

    Sametoglu, Ferhat

    2008-11-01

    Detector-based calibrating methods and expressions for calculation of photometric uncertainties related to uncertainties in the calibrations of luminous intensity of a light source, illuminance responsivity of a photometer head, and calibration factors of an illuminance meter are discussed. These methods permit luminous intensity calibrations of incandescent light sources, luminous responsivity calibrations of photometer heads, and calibration factors of illuminance meters to be carried out with relative expanded uncertainties (with a level of confidence of 95.45%) of 0.4%, 0.4%, and 0.6%, respectively.

  1. Mechanical Thrombectomy of Iliocaval Thrombosis Using a Protective Expandable Sheath

    SciTech Connect

    Truong, Tri H.; Spuentrup, Elmar; Staatz, Gundula; Wildberger, Joachim E.; Schmitz-Rode, Thomas; Nolte-Ernsting, Claus C.A.; Guenther, Rolf W.; Haage, Patrick

    2004-09-15

    We report a case of successful percutaneous treatment of a subacute ilio-caval venous thrombosis in a 64-year-old female patient by using a novel combination of a rotatory fragmentation device (percutaneous thrombectomy device: PTD) and large wire basket (temporary Guenther basket filter) under temporary caval filter protection using an expandable sheath. Because the patient had multiple myeloma with increased risk for contrast media-induced renal failure, the therapeutic angiographic procedure was performed without iodinated contrast medium. Non-contrast-enhanced MR venography (high-resolution True FISP) confirmed the effective thrombus removal by the percutaneous mechanical thrombectomy procedure.

  2. Army Reserve Expands Net Zero Energy, Water, Waste

    SciTech Connect

    Solana, Amy E.

    2015-04-14

    In 2012, the Army initiated a Net Zero (NZ) program to establish NZ energy, water, and/or waste goals at installations across the U.S. In 2013, the U.S. Army Reserve expanded this program to cover all three categories at different types of Reserve Centers (RCs) across 5 regions. Projects identified at 10 pilot sites resulted in an average savings potential from recommended measures of 90% for energy, 60% for water, and 83% for waste. This article provides results of these efforts.

  3. Beyond the numbers: expanding the boundaries of neuropsychology.

    PubMed

    Perry, William

    2009-02-01

    Beyond the Numbers: Expanding the Boundaries of Neuropsychology was Dr Perry's 2007 presidential address in the annual conference of the National Academy of Neuropsychology. In his address he discussed the achievements of the science of neuropsychology and highlighted some areas that exemplified the expansion of the boundaries of neuropsychology. These areas are: (i) the study of neuropsychological functioning in new or non-traditional populations, particularly seemingly healthy people and people with non-brain diseases; (ii) the interface of cognition and genetics; (iii) the use of the process approach as a means of understanding brain functioning; and (iv) a translational application to the science of neuropsychology.

  4. Expanding the Frontiers of Visual Analytics and Visualization

    SciTech Connect

    Dill, John; Earnshaw, Rae; Kasik, David; Vince, John; Wong, Pak C.

    2012-05-31

    Expanding the Frontiers of Visual Analytics and Visualization contains international contributions by leading researchers from within the field. Dedicated to the memory of Jim Thomas, the book begins with the dynamics of evolving a vision based on some of the principles that Jim and colleagues established and in which Jim’s leadership was evident. This is followed by chapters in the areas of visual analytics, visualization, interaction, modelling, architecture, and virtual reality, before concluding with the key area of technology transfer to industry.

  5. “Ripples” on a relativistically expanding fluid

    DOE PAGES

    Shi, Shuzhe; Liao, Jinfeng; Zhuang, Pengfei

    2014-12-29

    Recent studies have shown that fluctuations of various types play important roles in the evolution of the fireball created in relativistic heavy ion collisions and bear many phenomenological consequences for experimental observables. In addition, the bulk dynamics of the fireball is well described by relativistic hydrodynamic expansion and the fluctuations on top of such expanding background can be studied within the linearized hydrodynamic framework. In this paper we present complete and analytic sound wave solutions on top of both Bjorken flow and Hubble flow backgrounds.

  6. Expanded HOXA13 polyalanine tracts in a monotreme.

    PubMed

    Lehoczky, Jessica A; Innis, Jeffrey W

    2008-01-01

    The N-terminal region of human HOXA13 has seven discrete polyalanine tracts. Our previous analysis of these tracts in multiple major vertebrate clades suggested that three are mammal-specific. We now report the N-terminal HOXA13 repetitive tract structures in the monotreme Tachyglossus aculeatus (echidna). Contrary to our expectations, echidna HOXA13 possesses a unique set of polyalanine tracts and an unprecedented polyglycine tract. The data support the conclusion that the emergence of expanded polyalanine tracts in proteins occurred very early in the stem lineage that gave rise to mammals, between 162 and 315 Ma. PMID:18638320

  7. Avoiding Intellectual Stagnation: The Starship as an Expander of Minds

    NASA Astrophysics Data System (ADS)

    Crawford, Ian A.

    2014-06-01

    Interstellar exploration will advance human knowledge and culture in multiple ways. Scientifically, it will advance our understanding of the interstellar medium, stellar astrophysics, planetary science and astrobiology. In addition, significant societal and cultural benefits will result from a programme of interstellar exploration and colonisation. Most important will be the cultural stimuli resulting from expanding the horizons of human experience, and increased opportunities for the spread and diversification of life and culture through the Galaxy. Ultimately, a programme of interstellar exploration may be the only way for human (and post-human) societies to avoid the intellectual stagnation predicted for the `end of history'.

  8. The Alaska Volcano Observatory - Expanded Monitoring of Volcanoes Yields Results

    USGS Publications Warehouse

    Brantley, Steven R.; McGimsey, Robert G.; Neal, Christina A.

    2004-01-01

    Recent explosive eruptions at some of Alaska's 52 historically active volcanoes have significantly affected air traffic over the North Pacific, as well as Alaska's oil, power, and fishing industries and local communities. Since its founding in the late 1980s, the Alaska Volcano Observatory (AVO) has installed new monitoring networks and used satellite data to track activity at Alaska's volcanoes, providing timely warnings and monitoring of frequent eruptions to the aviation industry and the general public. To minimize impacts from future eruptions, scientists at AVO continue to assess volcano hazards and to expand monitoring networks.

  9. Expanding General Relativity's Space by S-Denying

    NASA Astrophysics Data System (ADS)

    Rabounski, Dmitri; Smarandache, Florentins; Borissova, Larissa

    2016-05-01

    Applying the S-denying procedure to signature conditions in a four-dimensional pseudo-Riemannian space - i.e. changing one (or even all) of the conditions to be partially true and partially false. Obtaining five kinds of expanded space-time for General Relativity. Kind I permits the space-time to be in collapse. Kind II permits the space-time to change its own signature. Kind III has peculiarities, linked to the third signature condition. Kind IV permits regions where the metric fully degenerates: there may be non-quantum teleportation, and a home for virtual photons. Kind V is common for kinds I, II, III, and IV.

  10. Expanded and packed bed albumin adsorption on fluoride modified zirconia.

    PubMed

    Mullick, A; Griffith, C M; Flickinger, M C

    1998-11-01

    The expanded bed characteristics of 75-103microm fluoride-modified zirconia (FmZr) particles synthesized by a fed batch oil emulsion process were investigated. These particles are distinguished from commercially available expanded-bed adsorbents by virtue of their high density (2.8 g/cc) and the mixed mode protein retention mechanism which allows for the retention of both cationic and anionic proteins. The linear velocity versus bed porosity data agree with the Richardson-Zaki relationship with the terminal velocity in infinite medium of 2858.4 cm/h and a bed expansion index of 5.1. Residence time distribution (RTD) studies and bovine serum albumin (BSA) adsorption studies were performed as a function of the height of the settled bed to the column diameter (H:D) ratio and degree of bed expansion with superficial velocities of 440 to 870 cm/h. The settled bed, a 2x expanded bed, and a 3x expanded bed were studied for the H:D ratios of 1:1, 2:1, and 3:1. The dynamic binding capacity (DBC) at 5% breakthrough was low (2-8 mg BSA/mL settled bed) and was independent of the H:D ratio or the degree of bed expansion. The saturation DBC was 32.3 +/- 7.0 mg BSA/mL settled bed. The adsorption-desorption kinetics and intraparticle diffusion for protein adsorption on FmZr (38-75 micrometer) were investigated by studying the packed bed RTD and BSA adsorption as a function of temperature and flow rate. The data show that the adsorption-desorption kinetics along with intraparticle diffusion significantly influence protein adsorption on FmZr. Low residence times ( approximately 0.8 min) of BSA result in a DBC at 5% breakthrough which is 3.5-fold lower compared to that at 6-fold higher protein residence time. At low linear velocity (45 cm/h) the breakthrough curve is nearly symmetrical and becomes asymmetrical and more dispersed at higher linear velocity (270 cm/h) due to the influence of slow adsorption-desorption kinetics and intraparticle diffusion. Bioeng 60: 333-340, 1998. PMID

  11. Angiogenesis and osteogenesis in an orthopedically expanded suture

    NASA Technical Reports Server (NTRS)

    Chang, H. N.; Garetto, L. P.; Potter, R. H.; Katona, T. R.; Lee, C. H.; Roberts, W. E.

    1997-01-01

    The purpose of this study was to examine the angiogenic and the subsequent osteogenic responses during a 96-hour time-course after sutural expansion. Fifty rats were divided into: (1) a control group that received only angiogenic induction through injection of 5 ng/gm recombinant human endothelial cell growth factor (rhECGF); (2) an experimental group that received orthopedic expansion and rhECGF; (3) a sham group that received expansion and sodium chloride (NaCl) injection; and (4) a baseline group that received no expansion or injection. All rats were injected with 3H-thymidine (1.0 microCi/gm) 1 hour before death to label the DNA of S-phase cells. Demineralized sections (4 microm thick) were stained with hematoxylin and eosin. Angiogenesis and cell migration were analyzed with a previously established cell kinetics model. Analysis of variance was used to test the hypothesis that enhancement of angiogenesis stimulates reestablishment of osteogenic capability. Blood vessel number, area, and endothelial cell-labeled index significantly increased in experimental groups, but no difference was found between control and baseline groups. Labeled-pericyte index and activated pericyte numbers in the experimental group were also higher than in the sham groups. These results show that supplemental rhECGF enhances angiogenesis in expanded sutures but not in nonexpanded sutures. Data also suggest that pericytes are the source of osteoblasts in an orthopedically expanded suture.

  12. Droplet evolution in expanding flow of warm dense matter.

    PubMed

    Armijo, J; Barnard, J J

    2011-05-01

    We propose a simple, self-consistent kinetic model for the evolution of a mixture of droplets and vapor expanding adiabatically in vacuum after rapid, almost isochoric heating. We study the evolution of the two-phase fluid at intermediate times between the molecular and the hydrodynamic scales, focusing on out-of-equilibrium and surface effects. We use the van der Waals equation of state as a test bed to implement our model and study the phenomenology of the upcoming second neutralized drift compression experiment (NDCX-II) at Lawrence Berkeley National Laboratory (LBNL) that uses ion beams for target heating. We find an approximate expression for the temperature difference between the droplets and the expanding gas and we check it with numerical calculations. The formula provides a useful criterion to distinguish the thermalized and nonthermalized regimes of expansion. In the thermalized case, the liquid fraction grows in a proportion that we estimate analytically, whereas, in case of too rapid expansion, a strict limit for the evaporation of droplets is derived. The range of experimental situations is discussed. PMID:21728540

  13. Proposal for Certifying Expandable Planetary Surface Habitation Structures

    NASA Technical Reports Server (NTRS)

    Dorsey, John T.

    2011-01-01

    A factor-of-safety (FS) of 4.0 is currently used to design habitation structures made from structural soft goods. This approach is inconsistent with using a FS of 2.0 for metallic and polymeric composite pressure vessels as well as soft good structures such as space suits and parachutes. This inconsistency arises by using the FS to improperly account for the unknown effects of a variety of environmental and loading uncertainties. Using a 4.0 FS not only results in additional structural mass, it also makes it difficult to gain insight into the limitations of the material and/or product form and thus, it becomes difficult to make improvements. In order to bring consistency to the design and certification of expandable habitat structures, the approach used by the Federal Aviation Administration (FAA) to certify polymeric composite aircraft structures is used as a model and point of departure. A draft certification plan for Expandable Habitat Structures is developed in this paper and offered as an option for placing habitats made from soft goods on an equal footing with other structural implementations.

  14. Equal spacing and expanding schedules in children's categorization and generalization.

    PubMed

    Vlach, Haley A; Sandhofer, Catherine M; Bjork, Robert A

    2014-07-01

    To understand how generalization develops across the lifespan, researchers have examined the factors of the learning environment that promote the acquisition and generalization of categories. One such factor is the timing of learning events, which recent findings suggest may play a particularly important role in children's generalization. In the current study, we build on these findings by examining the impact of equally spaced versus expanding learning schedules on children's ability to generalize from studied exemplars of a given category to new exemplars presented on a later test. We found no significant effects of learning schedule when the generalization test was administered immediately after the learning phase, but there was a clear difference when the generalization test was delayed by 24h, with children in the expanding condition significantly outperforming children in the equally spaced learning condition. These results suggest that forgetting and retrieval dynamics may be lower level cognitive mechanisms promoting generalization and have several implications for broad theories of learning, cognition, and development. PMID:24613074

  15. A Study of Flexible Composites for Expandable Space Structures

    NASA Technical Reports Server (NTRS)

    Scotti, Stephen J.

    2016-01-01

    Payload volume for launch vehicles is a critical constraint that impacts spacecraft design. Deployment mechanisms, such as those used for solar arrays and antennas, are approaches that have successfully accommodated this constraint, however, providing pressurized volumes that can be packaged compactly at launch and expanded in space is still a challenge. One approach that has been under development for many years is to utilize softgoods - woven fabric for straps, cloth, and with appropriate coatings, bladders - to provide this expandable pressure vessel capability. The mechanics of woven structure is complicated by a response that is nonlinear and often nonrepeatable due to the discrete nature of the woven fiber architecture. This complexity reduces engineering confidence to reliably design and certify these structures, which increases costs due to increased requirements for system testing. The present study explores flexible composite materials systems as an alternative to the heritage softgoods approach. Materials were obtained from vendors who utilize flexible composites for non-aerospace products to determine some initial physical and mechanical properties of the materials. Uniaxial mechanical testing was performed to obtain the stress-strain response of the flexible composites and the failure behavior. A failure criterion was developed from the data, and a space habitat application was used to provide an estimate of the relative performance of flexible composites compared to the heritage softgoods approach. Initial results are promising with a 25% mass savings estimated for the flexible composite solution.

  16. Evolution of gravitational orbits in the expanding universe

    SciTech Connect

    Sereno, Mauro; Jetzer, Philippe

    2007-03-15

    The gravitational action of the smooth energy-matter components filling in the universe can affect the orbit of a planetary system. Changes are related to the acceleration of the cosmological scale size R. In a universe with significant dark matter, a gravitational system expands or contracts according to the amount and equation of state of the dark energy. At present time, the Solar System, according to the {lambda}CDM scenario emerging from observational cosmology, should be expanding if we consider only the effect of the cosmological background. Its fate is determined by the equation of state of the dark energy alone. The mean motion and periastron precession of a planet are directly sensitive to Re/R, whereas variations with time in the semimajor axis and eccentricity are related to its time variation. Actual bounds on the cosmological deceleration parameters q{sub 0} from accurate astrometric data of perihelion precession and changes in the third Kepler's law in the Solar System fall short of 10 orders of magnitude with respect to estimates from observational cosmology. Future radio-ranging measurements of outer planets could improve actual bounds by 5 orders of magnitude.

  17. The expanding regulatory universe of p53 in gastrointestinal cancer.

    PubMed

    Fesler, Andrew; Zhang, Ning; Ju, Jingfang

    2016-01-01

    Tumor suppresser gene TP53 is one of the most frequently deleted or mutated genes in gastrointestinal cancers. As a transcription factor, p53 regulates a number of important protein coding genes to control cell cycle, cell death, DNA damage/repair, stemness, differentiation and other key cellular functions. In addition, p53 is also able to activate the expression of a number of small non-coding microRNAs (miRNAs) through direct binding to the promoter region of these miRNAs.  Many miRNAs have been identified to be potential tumor suppressors by regulating key effecter target mRNAs. Our understanding of the regulatory network of p53 has recently expanded to include long non-coding RNAs (lncRNAs). Like miRNA, lncRNAs have been found to play important roles in cancer biology.  With our increased understanding of the important functions of these non-coding RNAs and their relationship with p53, we are gaining exciting new insights into the biology and function of cells in response to various growth environment changes. In this review we summarize the current understanding of the ever expanding involvement of non-coding RNAs in the p53 regulatory network and its implications for our understanding of gastrointestinal cancer.

  18. An expanded model of faculty vitality in academic medicine.

    PubMed

    Dankoski, Mary E; Palmer, Megan M; Nelson Laird, Thomas F; Ribera, Amy K; Bogdewic, Stephen P

    2012-12-01

    Many faculty in today's academic medical centers face high levels of stress and low career satisfaction. Understanding faculty vitality is critically important for the health of our academic medical centers, yet the concept is ill-defined and lacking a comprehensive model. Expanding on previous research that examines vital faculty in higher education broadly and in academic medical centers specifically, this study proposes an expanded model of the unique factors that contribute to faculty vitality in academic medicine. We developed an online survey on the basis of a conceptual model (N = 564) and used linear regression to investigate the fit of the model. We examined the relationships of two predictor variables measuring Primary Unit Climate and Leadership and Career and Life Management with an overall Faculty Vitality index comprised of three measures: Professional Engagement, Career Satisfaction, and Productivity. The findings revealed significant predictive relationships between Primary Unit Climate and Leadership, Career and Life Management, and Faculty Vitality. The overall model accounted for 59% of the variance in the overall Faculty Vitality Index. The results provide new insights into the developing model of faculty vitality and inform initiatives to support faculty in academic medical centers. Given the immense challenges faced by faculty, now more than ever do we need reliable evidence regarding what sustains faculty vitality.

  19. LONGITUDINAL OSCILLATIONS IN DENSITY STRATIFIED AND EXPANDING SOLAR WAVEGUIDES

    SciTech Connect

    Luna-Cardozo, M.; Verth, G.; Erdelyi, R. E-mail: robertus@sheffield.ac.uk

    2012-04-01

    Waves and oscillations can provide vital information about the internal structure of waveguides in which they propagate. Here, we analytically investigate the effects of density and magnetic stratification on linear longitudinal magnetohydrodynamic (MHD) waves. The focus of this paper is to study the eigenmodes of these oscillations. It is our specific aim to understand what happens to these MHD waves generated in flux tubes with non-constant (e.g., expanding or magnetic bottle) cross-sectional area and density variations. The governing equation of the longitudinal mode is derived and solved analytically and numerically. In particular, the limit of the thin flux tube approximation is examined. The general solution describing the slow longitudinal MHD waves in an expanding magnetic flux tube with constant density is found. Longitudinal MHD waves in density stratified loops with constant magnetic field are also analyzed. From analytical solutions, the frequency ratio of the first overtone and fundamental mode is investigated in stratified waveguides. For small expansion, a linear dependence between the frequency ratio and the expansion factor is found. From numerical calculations it was found that the frequency ratio strongly depends on the density profile chosen and, in general, the numerical results are in agreement with the analytical results. The relevance of these results for solar magneto-seismology is discussed.

  20. The expanding regulatory universe of p53 in gastrointestinal cancer.

    PubMed

    Fesler, Andrew; Zhang, Ning; Ju, Jingfang

    2016-01-01

    Tumor suppresser gene TP53 is one of the most frequently deleted or mutated genes in gastrointestinal cancers. As a transcription factor, p53 regulates a number of important protein coding genes to control cell cycle, cell death, DNA damage/repair, stemness, differentiation and other key cellular functions. In addition, p53 is also able to activate the expression of a number of small non-coding microRNAs (miRNAs) through direct binding to the promoter region of these miRNAs.  Many miRNAs have been identified to be potential tumor suppressors by regulating key effecter target mRNAs. Our understanding of the regulatory network of p53 has recently expanded to include long non-coding RNAs (lncRNAs). Like miRNA, lncRNAs have been found to play important roles in cancer biology.  With our increased understanding of the important functions of these non-coding RNAs and their relationship with p53, we are gaining exciting new insights into the biology and function of cells in response to various growth environment changes. In this review we summarize the current understanding of the ever expanding involvement of non-coding RNAs in the p53 regulatory network and its implications for our understanding of gastrointestinal cancer. PMID:27508057