Science.gov

Sample records for acetate copolymer eva

  1. Preparation and Properties of Ethylene Vinyl Acetate Copolymer/Silica Nanocomposites in Presence of EVA-g-Acrylic Acid.

    PubMed

    Tham, Do Quang; Tuan, Vu Manh; Thanh, Dinh Thi Mai; Chinh, Nguyen Thuy; Giang, Nguyen Vu; Trang, Nguyen Thi Thu; Hang, To Thi Xuan; Huong, Ho Thu; Dung, Nguyen Thi Kim; Hoang, Thai

    2015-04-01

    Here we report a facile approach to enhance the dispersibility of ethylene vinyl acetate copolymer (EVA)/silica nanocomposites (for the EVA/silica nanocomposites and interaction between silica nanoparticles (nanosilica) and EVA by adding EVA-g-acrylic acid (EVAgAA) as a compatibilizer, which was formed by grafting acrylic acid onto EVA chains with the aid of dicumyl peroxide). The above nanocomposites with and without EVAgAA were prepared by melt mixing in a Haake intermixer with different contents of silica and EVAgAA. Their structure and morphology were characterized by Fourier transform infra-red (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM), and the mechanical, rheological, dielectrical, and flammability properties of the nanocomposites were also investigated. The FT-IR spectra of the nanocomposites confirmed the formation of hydrogen bonds between the surface silanol groups of nanosilica and C=O groups of EVA and/or EVAgAA. The presence of EVAgAA remarkably increased the intensity of hydrogen bonding between nanosilica and EVA which not only enhanced the dispersion of nanosilica in EVA matrix but also increased the mechanical, viscosity and storage modulus of EVA/silica nanocomposites. In addition, the flammability of EVA/silica nanocomposites is also significantly reduced after the functionalization with EVAgAA. However, the mechanical properties of EVA/silica nanocomposites tended to level off when its content was above 1.5 wt.%. It has also been found that the dielectric constant value of the EVA/EVAgAA/silica nanocomposites is much lower than that of the EVA/silica nanocomposites, which is another evidence of the hydrogen bonding formation between EVAgAA and nanosilica.

  2. Pre-dispersed organo-montmorillonite (organo-MMT) nanofiller: Morphology, cytocompatibility and impact on flexibility, toughness and biostability of biomedical ethyl vinyl acetate (EVA) copolymer.

    PubMed

    Osman, Azlin F; M Fitri, Tuty Fareyhynn; Rakibuddin, Md; Hashim, Fatimah; Tuan Johari, Syed Ahmad Tajudin; Ananthakrishnan, Rajakumar; Ramli, Rafiza

    2017-05-01

    Polymer-clay based nanocomposites are among the attractive materials to be applied for various applications, including biomedical. The incorporation of the nano sized clay (nanoclay) into polymer matrices can result in their remarkable improvement in mechanical, thermal and barrier properties as long as the nanofillers are well exfoliated and dispersed throughout the matrix. In this work, exfoliation strategy through pre-dispersing process of the organically modified montmorillonite (organo-MMT) nanofiller was done to obtain ethyl vinyl acetate (EVA) nanocomposite with improved flexibility, toughness, thermal stability and biostability. Our results indicated that the degree of organo-MMT exfoliation affects its cytotoxicity level and the properties of the resulting EVA nanocomposite. The pre-dispersed organo-MMT by ultrasonication in water possesses higher degree of exfoliation as compared to its origin condition and significantly performed reduced cytotoxicity level. Beneficially, this nanofiller also enhanced the EVA flexibility, thermal stability and biostability upon the in vitro exposure. We postulated that these were due to plasticizing effect and enhanced EVA-nanofiller interactions contributing to more stable chemical bonds in the main copolymer chains. Improvement in copolymer flexibility is beneficial for close contact with human soft tissue, while enhancement in toughness and biostability is crucial to extend its life expectancy as insulation material for implantable device.

  3. Drug release from cast films of ethylene vinyl acetate (EVA) copolymer: Stability of drugs by 1H NMR and solid state 13C CP/MAS NMR.

    PubMed

    Kalachandra, S; Lin, D M; Stejskal, E O; Prakki, A; Offenbacher, S

    2005-07-01

    The study utilizes an oral biocompatible material based on ethylene vinyl acetate copolymer (EVA) designed to release drugs in vitro at therapeutic levels over several days. We examined the drug stability during film casting process using proton and solid state NMR techniques. The drug-loaded EVA films were prepared from the dry sheet obtained by solvent (dichloromethane) evaporation of polymer casting solutions. Drugs tested include chlorhexidine diacetate (CDA), doxycycline hydrochloride (DOH), tetracycline hydrochloride (TTH) and nystatin (NST). Drug release from the films was examined for at least 14 days in 10 ml ddH2O (NST in water/ethanol (4:1)) which was replaced daily. Changes in optical density were followed spectraphotometrically. Effect of temperature on rate measurements was studied and the energies of activation (E*) were calculated using Arrhenius plots. Effect of EVA copolymer composition on CDA release rate was also investigated. The enhanced rates with temperature increase may be attributed to the formation of channels with increased geometry in the polymer. The highest E* observed for CDA compared to DOH and TTH may be related to their average molecular weights. Spectral analyses for CDA and NST revealed that the chemical and physical structures of the drugs remained unaffected during the film casting process.

  4. Development of an injection molded ethylene-vinyl acetate copolymer (EVA) intravaginal insert for the delivery of progesterone to cattle.

    PubMed

    Cappadoro, A J; Luna, J A

    2015-07-01

    The purpose of this study was to develop a new injection-molded intravaginal insert manufactured from ethylene-vinyl acetate containing progesterone for a 7-day insertion period in cattle. The manufacturing process resulted in a reduction in the residual drug compared to the silicone insert available while still maintaining biological performance.

  5. Preirradiation grafting of ethylene vinyl acetate copolymer resins

    NASA Astrophysics Data System (ADS)

    Ringrose, B. J.; Kronfli, E.

    1999-07-01

    Acrylic acid was graft copolymerised on to EVA powdered resins containing 9%, 18% and 28% vinyl acetate. A preirradiation grafting method was used and the effect on graft level of varying the parameters of gamma irradiation dose (2-50 kGy), dose rate (0.5-5 kGy h -1), monomer concentration (2.5-25%) and grafting time (1-4 h) and temperature (35-98°C) was investigated. The graft copolymer resins were converted into film and characterised in terms of their hydrophilicity and electrolytic resistance in alkaline solutions. Depending on the vinyl acetate content and rheological properties of the base EVA copolymer, high graft weight resins can be converted into semipermeable films suitable for a range of applications including battery separator membranes and topical medical dressings.

  6. 21 CFR 177.1350 - Ethylene-vinyl acetate copolymers.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Ethylene-vinyl acetate copolymers. 177.1350... Use Food Contact Surfaces § 177.1350 Ethylene-vinyl acetate copolymers. Ethylene-vinyl acetate... with the following prescribed conditions: (a)(1) Ethylene-vinyl acetate copolymers consist of...

  7. Space charge behaviour in maleic anhydride grafted polyethylene/ethylene - vinyl - acetate copolymer laminates

    NASA Astrophysics Data System (ADS)

    Lee, Seung Hyung; Park, Jung Ki; Han, Jae Hong; Suh, Kwang S.

    1997-01-01

    Charge distributions in maleic anhydride (MAH) grafted polyethylene (g-PE)/ethylene - vinyl - acetate (EVA) copolymer laminates have been measured with materials of different composition. All laminates showed interfacial charge, the polarity and the magnitude of which are explained by interfacial polarization. It was found that the interfacial charge increased with the increase of MAH content in the g-PE, whereas it decreased with the increase of vinyl - acetate content in the EVA. This feature was attributed to the differences in electrical conductivity of the materials. Details of the experimental results are described.

  8. Compatible blends of thermoplastic starch and hydrolyzed ethylene-vinyl acetate copolymers.

    PubMed

    Da Róz, A L; Ferreira, A M; Yamaji, F M; Carvalho, A J F

    2012-09-01

    Ethylene-vinyl acetate copolymer (EVA) with 19% of vinyl acetate and its derivatives modified by hydrolysis of 50 and 100% of the initial vinyl acetate groups were used to produce blends with thermoplastic starch (TPS) plasticized with 30 wt% glycerol. The blends were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, water absorption, stress-strain mechanical tests, dynamic mechanical analysis and thermogravimetric analysis. In contrast to the blends with unmodified EVA, those made with hydrolyzed EVA were compatible, as demonstrated by the brittle fracture surface analysis and the results of thermal and mechanical tests. The mechanical characteristics and water absorption of the TPS were improved even with a small addition (2.5 wt%) of hydrolyzed EVA. The glass transition temperature rose with the degree of hydrolysis of EVA by 40 and 50°, for the EVA with 50 and 100% hydrolysis, respectively. The addition of hydrolyzed EVA proved to be an interesting approach to improving TPS properties, even when very small quantities were used, such as 2.5 wt%.

  9. 21 CFR 177.1350 - Ethylene-vinyl acetate copolymers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Ethylene-vinyl acetate copolymers. 177.1350... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1350 Ethylene-vinyl acetate copolymers. Ethylene-vinyl acetate copolymers may be safely used as articles or components of...

  10. 21 CFR 177.1350 - Ethylene-vinyl acetate copolymers.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ethylene-vinyl acetate copolymers. 177.1350 Section... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1350 Ethylene-vinyl acetate copolymers. Ethylene-vinyl acetate copolymers may be safely used as articles or components of...

  11. 21 CFR 177.1350 - Ethylene-vinyl acetate copolymers.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Ethylene-vinyl acetate copolymers. 177.1350... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1350 Ethylene-vinyl acetate copolymers. Ethylene-vinyl acetate copolymers may be safely used as articles or components of...

  12. 21 CFR 177.1350 - Ethylene-vinyl acetate copolymers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Ethylene-vinyl acetate copolymers. 177.1350... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1350 Ethylene-vinyl acetate copolymers. Ethylene-vinyl acetate copolymers may be safely used as articles or components of...

  13. Comparative study on the effect of electron beam irradiation on the physical properties of ethylene-vinyl acetate copolymer composites

    NASA Astrophysics Data System (ADS)

    Wang, Bibo; Hong, Ningning; Shi, Yongqian; Wang, Biao; Sheng, Haibo; Song, Lei; Tang, Qinbo; Hu, Yuan

    2014-04-01

    Ethylene-vinyl acetate copolymer (EVA) flame retarded by a combination of cellulose acetate butyrate (CAB) microencapsulated ammonium polyphosphate (MCAPP) and polyamide-6 (PA-6) have been crosslinked by high energy electron beam irradiation. The effect of high energy electron beam irradiation on the crosslinking degree, mechanical, electrical and thermal properties of EVA/MCAPP/PA-6 cable material was studied by gel content, heat extention test, mechanical test, dynamic mechanical analysis, high-insulation resistance meter and thermogravimetric analysis. The gel content and heat extention test results showed that the EVA/MCAPP/PA-6 composites can be easily crosslinked by electron beam irradiation. The tensile strength of EVA composites was drastically increased from 16.2 to maximum 26.2 MPa as the electron beam irradiation dose increases from 0 to 160 kGy. The volatilized products of EVA/MCAPP/PA-6 composites were analyzed and compared by thermogravimetric analysis/infrared spectrometry (TG-FTIR).

  14. Ethylene vinyl acetate (EVA) as a new drug carrier for 3D printed medical drug delivery devices.

    PubMed

    Genina, Natalja; Holländer, Jenny; Jukarainen, Harri; Mäkilä, Ermei; Salonen, Jarno; Sandler, Niklas

    2016-07-30

    The main purpose of this work was to investigate the printability of different grades of ethylene vinyl acetate (EVA) copolymers as new feedstock material for fused-deposition modeling (FDM™)-based 3D printing technology in fabrication of custom-made T-shaped intrauterine systems (IUS) and subcutaneous rods (SR). The goal was to select an EVA grade with optimal properties, namely vinyl acetate content, melting index, flexural modulus, for 3D printing of implantable prototypes with the drug incorporated within the entire matrix of the medical devices. Indomethacin was used as a model drug in this study. Out of the twelve tested grades of the EVA five were printable. One of them showed superior print quality and was further investigated by printing drug-loaded filaments, containing 5% and 15% indomethacin. The feedstock filaments were fabricated by hot-melt extrusion (HME) below the melting point of the drug substance and the IUS and SR were successfully printed at the temperature above the melting point of the drug. As a result, the drug substance in the printed prototypes showed to be at least partly amorphous, while the drug in the corresponding HME filaments was crystalline. This difference affected the drug release profiles from the filaments and printed prototype products: faster release from the prototypes over 30days in the in vitro tests. To conclude, this study indicates that certain grades of EVA were applicable feedstock material for 3D printing to produce drug-loaded implantable prototypes.

  15. Determination of the linear coefficient of thermal expansion in polymer films at the nanoscale: influence of the composition of EVA copolymers and the molecular weight of PMMA.

    PubMed

    González-Benito, J; Castillo, E; Cruz-Caldito, J F

    2015-07-28

    Nanothermal-expansion of poly(ethylene-co-vinylacetate), EVA, and poly(methyl methacrylate), PMMA, in the form of films was measured to finally obtain linear coefficients of thermal expansion, CTEs. The simple deflection of a cantilever in an atomic force microscope, AFM, was used to monitor thermal expansions at the nanoscale. The influences of: (a) the structure of EVA in terms of its composition (vinylacetate content) and (b) the size of PMMA chains in terms of the molecular weight were studied. To carry out this, several polymer samples were used, EVA copolymers with different weight percents of the vinylacetate comonomer (12, 18, 25 and 40%) and PMMA polymers with different weight average molecular weights (33.9, 64.8, 75.600 and 360.0 kg mol(-1)). The dependencies of the vinyl acetate weight fraction of EVA and the molecular weight of PMMA on their corresponding CTEs were analyzed to finally explain them using new, intuitive and very simple models based on the rule of mixtures. In the case of EVA copolymers a simple equation considering the weighted contributions of each comonomer was enough to estimate the final CTE above the glass transition temperature. On the other hand, when the molecular weight dependence is considered the free volume concept was used as novelty. The expansion of PMMA, at least at the nanoscale, was well and easily described by the sum of the weighted contributions of the occupied and free volumes, respectively.

  16. Effect of electron beam irradiation and microencapsulation on the flame retardancy of ethylene-vinyl acetate copolymer materials during hot water ageing test

    NASA Astrophysics Data System (ADS)

    Sheng, Haibo; Zhang, Yan; Wang, Bibo; Yu, Bin; Shi, Yongqian; Song, Lei; Kundu, Chanchal Kumar; Tao, Youji; Jie, Ganxin; Feng, Hao; Hu, Yuan

    2017-04-01

    Microencapsulated ammonium polyphosphate (MCAPP) in combination with polyester polyurethane (TPU) was used to flame retardant ethylene-vinyl acetate copolymer (EVA). The EVA composites with different irradiation doses were immersed in hot water (80 °C) to accelerate ageing process. The microencapsulation and irradiation dose ensured positive impacts on the properties of the EVA composites in terms of better dimensional stability and flame retardant performance. The microencapsulation of APP could lower its solubility in water and the higher irradiation dose led to the more MCAPP immobilized in three dimensional crosslinked structure of the EVA matrix which could jointly enhance the flame retardant and electrical insulation properties of the EVA composites. So, the EVA composites with 180 kGy irradiation dose exhibited better dimensional stability than the EVA composites with 120 kGy due to the higher crosslinking degree. Moreover, the higher irradiation dose lead to the more MCAPP immobilizated in crosslinked three-dimensional structure of EVA, enhancing the flame retardancy and electrical insulation properties of the EVA composites. After ageing test in hot water at 80 °C for 2 weeks, the EVA/TPU/MCAPP composite with 180 kGy could still maintain the UL-94 V-0 rating and the limiting oxygen index (LOI) value was as high as 30%. This investigation indicated the flame retardant EVA cable containing MCAPP could achieve stable properties and lower electrical fire hazard risk during long-term hot water ageing test.

  17. Enhancing the thermal conductivity of ethylene-vinyl acetate (EVA) in a photovoltaic thermal collector

    NASA Astrophysics Data System (ADS)

    Allan, J.; Pinder, H.; Dehouche, Z.

    2016-03-01

    Samples of Ethylene-Vinyl Acetate (EVA) were doped with particles of Boron Nitride (BN) in concentrations ranging from 0-60% w/w. Thermal conductivity was measured using a Differential Scanning Calorimetery (DSC) technique. The thermal conductivity of parent EVA was increased from 0.24W/m ṡ K to 0.80W/m ṡ K for the 60% w/w sample. Two PV laminates were made; one using the parent EVA the other using EVA doped with 50% BN. When exposed to a one directional heat flux the doped laminate was, on average, 6% cooler than the standard laminate. A finite difference model had good agreement with experimental results and showed that the use of 60% BN composite achieved a PV performance increase of 0.3% compared to the standard laminate.

  18. 21 CFR 175.350 - Vinyl acetate/crotonic acid copolymer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Vinyl acetate/crotonic acid copolymer. 175.350... COATINGS Substances for Use as Components of Coatings § 175.350 Vinyl acetate/crotonic acid copolymer. A copolymer of vinyl acetate and crotonic acid may be safely used as a coating or as a component of a...

  19. 21 CFR 177.1360 - Ethylene-vinyl acetate-vinyl alcohol copolymers.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ethylene-vinyl acetate-vinyl alcohol copolymers... for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1360 Ethylene-vinyl acetate-vinyl alcohol copolymers. Ethylene-vinyl acetate-vinyl alcohol copolymers (CAS Reg. No....

  20. 21 CFR 177.1360 - Ethylene-vinyl acetate-vinyl alcohol copolymers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Ethylene-vinyl acetate-vinyl alcohol copolymers... for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1360 Ethylene-vinyl acetate-vinyl alcohol copolymers. Ethylene-vinyl acetate-vinyl alcohol copolymers (CAS Reg. No....

  1. 21 CFR 177.1360 - Ethylene-vinyl acetate-vinyl alcohol copolymers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Ethylene-vinyl acetate-vinyl alcohol copolymers... for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1360 Ethylene-vinyl acetate-vinyl alcohol copolymers. Ethylene-vinyl acetate-vinyl alcohol copolymers (CAS Reg. No....

  2. 21 CFR 177.1360 - Ethylene-vinyl acetate-vinyl alcohol copolymers.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Ethylene-vinyl acetate-vinyl alcohol copolymers... Repeated Use Food Contact Surfaces § 177.1360 Ethylene-vinyl acetate-vinyl alcohol copolymers. Ethylene... conditions: (a) Ethylene-vinyl acetate-vinyl alcohol copolymers are produced by the partial or...

  3. 21 CFR 177.1360 - Ethylene-vinyl acetate-vinyl alcohol copolymers.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Ethylene-vinyl acetate-vinyl alcohol copolymers... for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1360 Ethylene-vinyl acetate-vinyl alcohol copolymers. Ethylene-vinyl acetate-vinyl alcohol copolymers (CAS Reg. No....

  4. EVA thin film with thermo- and moisture-stable luminescent copolymer beads composed of Eu(III) complexes for improvement of energy conversion efficiency on silicon solar cell

    NASA Astrophysics Data System (ADS)

    Kataoka, Hisataka; Omagari, Shun; Nakanishi, Takayuki; Hasegawa, Yasuchika

    2015-04-01

    Luminescent beads composed of Eu(hfa)3(TPPO)2 (hfa: hexafluoroacetylacetonate, TPPO: triphenylphosphine oxide) in PMMA copolymer (polymethylmethacrylate- styrene and polymethylmethacrylate-trifluoromethylmethacrylate copolymers), PMMA-St-Eu and PMMA-TF-Eu have been reported for improvement of energy conversion efficiency on silicon solar cell. The PMMA-St-Eu and PMMA-TF-Eu beads are prepared using radical initiator AIBN (2,2-azobisisobutyronitrile) without BPO (Benzoyl peroxide) which promotes decomposition of Eu(hfa)3(TPPO)2. The emission properties of EVA (ethylene vinyl acetate) film with PMMA-St-Eu or PMMA-TF-Eu beads are characterized by the emission spectra and lifetimes. Thermo- and moisture-stabilities of the EVA films are performed under high temperature and high moisture condition (85°C85%RH). Increase percentage the solar cell short circuit current efficiency in the solar cell modulation using with EVA film containing PMMA-St-Eu beads with size in 70 μm was estimated to 1.2%. Thermo- and moisture-stable PMMA-St-Eu and PMMA-TF-Eu beads for solar sealing film are demonstrated for the first time.

  5. Beneficial effects of air inclusions on the performance of ethylene vinyl acetate (EVA) mouthguard material

    PubMed Central

    Westerman, B; Stringfellow, P; Eccleston, J

    2002-01-01

    Objective: To investigate the impact characteristics of an ethylene vinyl acetate (EVA) mouthguard material with regulated air inclusions, which included various air cell volumes and wall thickness between air cells. In particular, the aim was to identify the magnitude and direction of forces within the impacts. Method: EVA mouthguard material, 4 mm thick and with and without air inclusions, was impacted with a constant force impact pendulum with an energy of 4.4 J and a velocity of 3 m/s. Transmitted forces through the EVA material were measured using an accelerometer, which also allowed the determination of force direction and magnitude within the impacts. Results: Statistically significant reductions in the transmitted forces were observed with all the air inclusion materials when compared with EVA without air inclusions. Maximum transmitted force through one air inclusion material was reduced by 32%. Force rebound was eliminated in one material, and reduced second force impulses were observed in all the air inclusion materials. Conclusion: The regulated air inclusions improved the impact characteristics of the EVA mouthguard material, the material most commonly used in mouthguards world wide. PMID:11867493

  6. Multidimensional chromatographic techniques for hydrophilic copolymers II. Analysis of poly(ethylene glycol)-poly(vinyl acetate) graft copolymers.

    PubMed

    Knecht, Daniela; Rittig, Frank; Lange, Ronald F M; Pasch, Harald

    2006-10-13

    A large variety of hydrophilic copolymers is applied in different fields of chemical industry including bio, pharma and pharmaceutical applications. For example, poly(ethylene glycol)-poly(vinyl alcohol) graft copolymers that are used as tablet coatings are responsible for the controlled release of the active compounds. These copolymers are produced by grafting of vinyl acetate onto polyethylene glycol (PEG) and subsequent hydrolysis of the poly(ethylene glycol)-poly(vinyl acetate) graft copolymers. The poly(ethylene glycol)-poly(vinyl acetate) copolymers are distributed with regard to molar mass and chemical composition. In addition, they frequently contain the homopolymers polyethylene glycol and polyvinyl acetate. The comprehensive analysis of such complex systems requires hyphenated analytical techniques, including two-dimensional liquid chromatography and combined LC and nuclear magnetic resonance spectroscopy. The development and application of these techniques are discussed in the present paper.

  7. Effect of cellulose acetate butyrate microencapsulated ammonium polyphosphate on the flame retardancy, mechanical, electrical, and thermal properties of intumescent flame-retardant ethylene-vinyl acetate copolymer/microencapsulated ammonium polyphosphate/polyamide-6 blends.

    PubMed

    Wang, Bibo; Tang, Qinbo; Hong, Ningning; Song, Lei; Wang, Lei; Shi, Yongqian; Hu, Yuan

    2011-09-01

    Ammonium polyphosphate (APP), a widely used intumescent flame retardant, has been microencapsulated by cellulose acetate butyrate with the aim of enhancing the water resistance of APP and the compatibility between the ethylene-vinyl acetate copolymer (EVA) matrix and APP. The structure of microencapsulated ammonium polyphosphate (MCAPP) was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and water contact angle (WCA). The flame retadancy and thermal stability were investigated by a limiting oxygen index (LOI) test, UL-94 test, cone calorimeter, and thermogravimetric analysis (TGA). The WCA results indicated that MCAPP has excellent water resistance and hydrophobicity. The results demonstrated that MCAPP enhanced interfacial adhesion, mechanical, electrical, and thermal stability of the EVA/MCAPP/polyamide-6 (PA-6) system. The microencapsulation not only imparted EVA/MCAPP/PA-6 with a higher LOI value and UL-94 rating but also could significantly improve the fire safety. Furthermore, the microencapsulated EVA/MCAPP/PA-6 composites can still pass the UL-94 V-0 rating after treatment with water for 3 days at 70 °C, indicating excellent water resistance. This investigation provides a promising formulation for the intumescent flame retardant EVA with excellent properties.

  8. Effect of Rare Earth Ions on the Properties of Composites Composed of Ethylene Vinyl Acetate Copolymer and Layered Double Hydroxides

    PubMed Central

    Wang, Lili; Li, Bin; Zhao, Xiaohong; Chen, Chunxia; Cao, Jingjing

    2012-01-01

    Background The study on the rare earth (RE)-doped layered double hydroxides (LDHs) has received considerable attention due to their potential applications in catalysts. However, the use of RE-doped LDHs as polymer halogen-free flame retardants was seldom investigated. Furthermore, the effect of rare earth elements on the hydrophobicity of LDHs materials and the compatibility of LDHs/polymer composite has seldom been reported. Methodology/Principal Findings The stearate sodium surface modified Ni-containing LDHs and RE-doped Ni-containing LDHs were rapidly synthesized by a coprecipitation method coupled with the microwave hydrothermal treatment. The influences of trace amounts of rare earth ions La, Ce and Nd on the amount of water molecules, the crystallinity, the morphology, the hydrophobicity of modified Ni-containing LDHs and the adsorption of modifier in the surface of LDHs were investigated by TGA, XRD, TEM, contact angle and IR, respectively. Moreover, the effects of the rare earth ions on the interfacial compatibility, the flame retardancy and the mechanical properties of ethylene vinyl acetate copolymer (EVA)/LDHs composites were also explored in detail. Conclusions/Significance S-Ni0.1MgAl-La displayed more uniform dispersion and better interfacial compatibility in EVA matrix compared with other LDHs. Furthermore, the S-Ni0.1MgAl-La/EVA composite showed the best fire retardancy and mechanical properties in all composites. PMID:22693627

  9. MALDI SpiralTOF high‐resolution mass spectrometry and Kendrick mass defect analysis applied to the characterization of poly(ethylene‐co‐vinyl acetate) copolymers

    PubMed Central

    Nakamura, Sayaka

    2016-01-01

    Rationale Poly(ethylene‐co‐vinyl acetate) copolymers – usually referred to as EVA – are first class industrial polymers used for applications ranging from padding to photovoltaics as encapsulant for the silicon solar cells. Various techniques have been used for their characterization but the analysis of intact EVA chains using mass spectrometry (MS) has not been reported so far. Methods Three copolymers containing 18, 25 and 40 wt% vinyl acetate (VA) have been characterized using an off‐line coupling of size‐exclusion chromatography (SEC) and matrix‐assisted laser desorption/ionization (MALDI) spiral‐time‐of‐flight (TOF) high‐resolution mass spectrometry (HRMS). The representativeness of those results for the entire samples has been checked using 13C NMR spectroscopy. Lastly, Kendrick mass defect analysis has been proposed as an alternative and user‐friendly data treatment method. Results The shortest chains isolated by SEC fractionation and mass‐analyzed by HRMS have been thoroughly described in terms of end‐groups (found to be hydrogens) and co‐monomeric composition. The VA content was successfully derived from the peak assignments in MS spectra for the EVA 40 wt% and 25 wt% while it tended to be overestimated for the latest EVA 18 wt% (increasing poly(ethylene) character). Similar results have been found using a faster data treatment method relying on the Kendrick mass defect analysis of the MS data. Conclusions EVA low molecular weight intact oligomers have been extensively characterized by MS for the first time and the structural features confidently extended to the full sample according to NMR data. The Kendrick mass analysis finally constituted an efficient method for a fast evaluation of their VA content with no need for manual assignment. © 2016 The Authors. Rapid Communications in Mass Spectrometry Published by John Wiley & Sons Ltd. PMID:26969940

  10. Property tuning of poly(lactic acid)/cellulose bio-composites through blending with modified ethylene-vinyl acetate copolymer.

    PubMed

    Pracella, Mariano; Haque, Md Minhaz-Ul; Paci, Massimo; Alvarez, Vera

    2016-02-10

    The effect of addition of an ethylene-vinyl acetate copolymer modified with glycidyl methacrylate (EVA-GMA) on the structure and properties of poly(lactic acid) (PLA) composites with cellulose micro fibres (CF) was investigated. Binary (PLA/CF) and ternary (PLA/EVA-GMA/CF) composites obtained by melt mixing in Brabender mixer were analysed by SEM, POM, WAXS, DSC, TGA and tensile tests. The miscibility and morphology of PLA/EVA-GMA blends were first examined as a function of composition: a large rise of PLA spherulite growth rate in the blends was discovered with increasing the EVA-GMA content (0-30 wt%) in the isothermal crystallization both from the melt and the solid state. PLA/EVA-GMA/CF ternary composites displayed improved adhesion and dispersion of fibres into the matrix as compared to PLA/CF system. Marked changes of thermodynamic and tensile parameters, as elastic modulus, strength and elongation at break were observed for the composites, depending on blend composition, polymer miscibility and fibre-matrix chemical interactions at the interface.

  11. Thermal Conductivity of Ethylene Vinyl Acetate Copolymer/Nanofiller Blends

    NASA Technical Reports Server (NTRS)

    Ghose, S.; Watson, K. A.; Working, D. C.; Connell, J. W.; Smith, J. G., Jr.; Lin, Y.; Sun, Y. P.

    2007-01-01

    To reduce weight and increase the mobility, comfort, and performance of future spacesuits, flexible, thermally conductive fabrics and plastic tubes are needed for the Liquid Cooling and Ventilation Garment. Such improvements would allow astronauts to operate more efficiently and safely for extended extravehicular activities. As an approach to raise the thermal conductivity (TC) of an ethylene vinyl acetate copolymer (Elvax 260), it was compounded with three types of carbon based nanofillers: multi-walled carbon nanotubes (MWCNTs), vapor grown carbon nanofibers (CNFs), and expanded graphite (EG). In addition, other nanofillers including metallized CNFs, nickel nanostrands, boron nitride, and powdered aluminum were also compounded with Elvax 260 in the melt at various loading levels. In an attempt to improve compatibility between Elvax 260 and the nanofillers, MWCNTs and EG were modified by surface coating and through noncovalent and covalent attachment of organic molecules containing alkyl groups. Ribbons of the nanocomposites were extruded to form samples in which the nanofillers were aligned in the direction of flow. Samples were also fabricated by compression molding to yield nanocomposites in which the nanofillers were randomly oriented. Mechanical properties of the aligned samples were determined by tensile testing while the degree of dispersion and alignment of nanoparticles were investigated using high-resolution scanning electron microscopy. TC measurements were performed using a laser flash (Nanoflash ) technique. TC of the samples was measured in the direction of, and perpendicular to, the alignment direction. Additionally, tubing was also extruded from select nanocomposite compositions and the TC and mechanical flexibility measured.

  12. Thermal Conductivity of Ethylene Vinyl Acetate Copolymer/Nanofiller Blends

    NASA Technical Reports Server (NTRS)

    Ghose, Sayata; Watson, Kent A.; Working, Dennis C.; Connell, John W.; Smith, Joseph G., Jr.; Lin, Y.; Sun, Y. P.

    2007-01-01

    To reduce weight and increase the mobility, comfort, and performance of future spacesuits, flexible, thermally conductive fabrics and plastic tubes are needed for the Liquid Cooling and Ventilation Garment. Such improvements would allow astronauts to operate more efficiently and safely for extended extravehicular activities. As an approach to raise the thermal conductivity (TC) of an ethylene vinyl acetate copolymer (Elvax(TM)260), it was compounded with three types of carbon based nanofillers: multi-walled carbon nanotubes (MWCNTs), vapor grown carbon nanofibers (CNFs), and expanded graphite (EG). In addition, other nanofillers including metallized CNFs, nickel nanostrands, boron nitride, and powdered aluminum were also compounded with Elvax(TM) 260 in the melt at various loading levels. In an attempt to improve compatibility between Elvax 260 and the nanofillers, MWCNTs and EG were modified by surface coating and through noncovalent and covalent attachment of organic molecules containing alkyl groups. Ribbons of the nanocomposites were extruded to form samples in which the nanofillers were aligned in the direction of flow. Samples were also fabricated by compression molding to yield nanocomposites in which the nanofillers were randomly oriented. Mechanical properties of the aligned samples were determined by tensile testing while the degree of dispersion and alignment of nanoparticles were investigated using high-resolution scanning electron microscopy. TC measurements were performed using a laser flash (Nanoflash(TM)) technique. TC of the samples was measured in the direction of, and perpendicular to, the alignment direction. Additionally, tubing was also extruded from select nanocomposite compositions and the TC and mechanical flexibility measured.

  13. Calibration models for the vinyl acetate concentration in ethylene-vinyl acetate copolymers and its on-line monitoring by near-infrared spectroscopy and chemometrics: use of band shifts associated with variations in the vinyl acetate concentration to improve the models.

    PubMed

    Watari, Masahiro; Ozaki, Yukihiro

    2005-07-01

    The present study investigates calibration models for the vinyl acetate (VA) concentration in ethylene-vinyl acetate (EVA) copolymers and its on-line monitoring by near-infrared (NIR) spectroscopy and chemometrics. The key point in the present study is to make use of band shifts associated with concentration changes in the vinyl acetate (VA) for the improvement of the models. NIR spectra of EVA in melt and solid states were measured by a Fourier transform near-infrared (FT-NIR) on-line monitoring system and a FT-NIR laboratory system. Some of the bands in the NIR spectra for both states show significant shifts with the variations in the VA concentration. The peak shifts induced by the VA concentration changes are larger in the solid-state EVA than those in the melt-state EVA. We have developed calibration models for the VA concentration in the solid-state EVA and investigated how to improve the calibration models. The factor analysis of partial least squares (PLS) regression has suggested that the wavenumber shifts caused by the VA concentration changes affect the calibration models for the VA concentration in EVA. From the analysis, it has been proposed that the wavenumbers in the spectrum of one sample in nine EVA samples (VA concentration range: 0-41.1%) are shifted for the improvement of the calibration models, and the effects of the proposed method have been confirmed by using the PLS calibration models for the VA concentration in the solid EVA samples. As the next step, the effects of the wavenumber shift method have been explored for the calibration models for the VA concentration in the melt-state EVA. After that, the discrimination method using the score plots of PLS and the application sequence for the on-line monitoring to use the proposed wavenumber shift method were studied. The simulation results using the discrimination and wavenumber shift methods have shown that those methods are very effective to improve the predicted values of the calibration

  14. Thermal and chemical stabilization of ethylene/vinyl acetate/vinyl alcohol (EVA-OH) terpolymers under nitroplasticizer environments

    SciTech Connect

    Yang, Dali; Hubbard, Kevin M.; Henderson, Kevin C.; Labouriau, Andrea

    2014-09-17

    Here, we compare the aging behaviors of cross-linked ethylene/vinyl acetate/vinyl alcohol terpolymers, also referred to as EVA-OH, when they are either immersed in nitroplasticizer (NP) liquid or exposed to NP vapor at different temperatures. And while thermogravimetric analysis and differential scanning calorimetry are used to probe the thermal stability of aged NP and polymers, Fourier transform infrared, gel permeation chromatography, ultra-violet/vis, and nuclear magnetic resonance are used to probe their structural changes over the aging process. Our study confirms that NP degrades through C[BOND]N cleavage, and releases HONO molecules at a slightly elevated temperature (<75°C). As these molecules accumulate in the vapor phase, they react among themselves to create an acidic environment. Therefore, these chemical constituents in the NP vapor significantly accelerate the hydrolysis of EVA-OH polymer. When the hydrolysis occurs in both vinyl acetate and urethane groups and the scission at the cross-linker progresses, EVA-OH becomes vulnerable to further degradation in the NP vapor environment. Finally, through the comprehensive characterization, the possible degradation mechanisms of the terpolymers are proposed.

  15. Thermal and chemical stabilization of ethylene/vinyl acetate/vinyl alcohol (EVA-OH) terpolymers under nitroplasticizer environments

    DOE PAGES

    Yang, Dali; Hubbard, Kevin M.; Henderson, Kevin C.; ...

    2014-09-17

    Here, we compare the aging behaviors of cross-linked ethylene/vinyl acetate/vinyl alcohol terpolymers, also referred to as EVA-OH, when they are either immersed in nitroplasticizer (NP) liquid or exposed to NP vapor at different temperatures. And while thermogravimetric analysis and differential scanning calorimetry are used to probe the thermal stability of aged NP and polymers, Fourier transform infrared, gel permeation chromatography, ultra-violet/vis, and nuclear magnetic resonance are used to probe their structural changes over the aging process. Our study confirms that NP degrades through C[BOND]N cleavage, and releases HONO molecules at a slightly elevated temperature (<75°C). As these molecules accumulate inmore » the vapor phase, they react among themselves to create an acidic environment. Therefore, these chemical constituents in the NP vapor significantly accelerate the hydrolysis of EVA-OH polymer. When the hydrolysis occurs in both vinyl acetate and urethane groups and the scission at the cross-linker progresses, EVA-OH becomes vulnerable to further degradation in the NP vapor environment. Finally, through the comprehensive characterization, the possible degradation mechanisms of the terpolymers are proposed.« less

  16. 21 CFR 175.350 - Vinyl acetate/crotonic acid copolymer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Vinyl acetate/crotonic acid copolymer. 175.350 Section 175.350 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) INDIRECT FOOD ADDITIVES: ADHESIVES AND COMPONENTS OF COATINGS Substances for Use as Components...

  17. 21 CFR 175.350 - Vinyl acetate/crotonic acid copolymer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Vinyl acetate/crotonic acid copolymer. 175.350 Section 175.350 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: ADHESIVES AND COMPONENTS...

  18. 21 CFR 175.350 - Vinyl acetate/crotonic acid copolymer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Vinyl acetate/crotonic acid copolymer. 175.350 Section 175.350 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: ADHESIVES AND COMPONENTS...

  19. 21 CFR 175.350 - Vinyl acetate/crotonic acid copolymer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Vinyl acetate/crotonic acid copolymer. 175.350 Section 175.350 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: ADHESIVES AND COMPONENTS...

  20. Thermoplastic rubber comprising ethylene-vinyl acetate copolymer, asphalt and fluxing oil

    NASA Technical Reports Server (NTRS)

    Hendel, F. J. (Inventor)

    1970-01-01

    A thermoplastic rubber is made from a mixture of between about 10 percent and about 50 percent of asphalt, between about 5 percent and about 30 percent fluxing oil, and between about 35 percent and about 70 percent of a copolymer of polyethylene and vinyl acetate.

  1. Effect of chain structure on hydrogen bonding in vinyl acetate - vinyl alcohol copolymers

    NASA Astrophysics Data System (ADS)

    Merekalova, Nadezhda D.; Bondarenko, Galina N.; Denisova, Yuliya I.; Krentsel, Liya B.; Litmanovich, Arkadiy D.; Kudryavtsev, Yaroslav V.

    2017-04-01

    FTIR spectroscopy and semi-empirical AM1 method are used to study hydrogen bonding in multiblock and random equimolar copolymers of vinyl acetate and vinyl alcohol. An energetically beneficial zip-holder complex, built on multiple inter- and intrachain hydroxyl-hydroxyl bonds and an intrachain hydroxyl-acetyloxy bond, can be formed between two vinyl alcohol sequences. As a result, multiblock copolymers reveal stronger degree of association that affects crystallinity, as well as various rheological and relaxation properties discussed in the literature. Macromolecular complexes in random copolymers are weak and tend to be destroyed in the presence of residual DMF solvent and adsorbed water. Nevertheless, a rather stable interchain quaternary complex can be formed that includes vinyl alcohol and vinyl acetate units and DMF and water molecules. For a single chain it is shown that an H-bond between neighboring vinyl alcohol and vinyl acetate monomer units mostly engages a carbonyl oxygen atom of the vinyl acetate, if the vinyl alcohol belongs to a short (<5 units) sequence, and an ether oxygen atom in the other case. On the whole, the quantum chemistry calculations shed much light on the origin of distinctions in the copolymer FTIR spectra, which may seem subtle when considered standalone.

  2. Electron beam irradiation induced compatibilization of immiscible polyethylene/ethylene vinyl acetate (PE/EVA) blends: Mechanical properties and morphology stability

    NASA Astrophysics Data System (ADS)

    Entezam, Mehdi; Aghjeh, Mir Karim Razavi; Ghaffari, Mehdi

    2017-02-01

    Gel content, mechanical properties and morphology of immiscible PE/EVA blends irradiated by high energy electron beam were studied. The results of gel content measurements showed that the capability of cross-linking of the blend samples increased with an increase of the EVA composition. Also, the gel content for most compositions of the blends displayed a positive deviation from the additive rule. The results of mechanical properties showed that the tensile strength and elongation at break of the samples increased and decreased, respectively, with irradiation dose. On the other hand, the mechanical properties of the irradiated blends also depicted a positive deviation from additive rule contrary to the un-irradiated blends. A synergistic effect observed for the mechanical properties improvement of the irradiated blends and it was attributed to the probable formation of the PE-graft-EVA copolymers at the interface of the blends during the irradiation process. A theoretical analysis revealed that irradiation induced synergistic effect was more significant for EVA-rich blends with weaker interfacial interaction as compared to PE-rich blends. The morphological analysis indicated that the blend morphology was not affected obviously, whereas it was stabilized by irradiation.

  3. Oral 4-week and 13-week toxicity studies of polyvinyl acetate vinyl laurate copolymer in rats.

    PubMed

    Messinger, Horst; Bär, Albert

    2014-10-01

    Polyvinyl acetate vinyl laurate copolymer (PVAcVL) is a useful component of gum base for chewing gum production. The safety of PVAcVL was examined in a 4-week and a 13-week oral toxicity study in rats. Finely powdered PVAcVL was administered with the diet at levels of 1.25%, 2.0% and 5% in the 4-week study and 1.25%, 2.5% and 5% in the 13-week study. There were no treatment related effects on mortality, bodyweight gains feed efficiency, ophthalmoscopic findings, hematological and clinical chemical parameters, neurobehavioral observations as well as gross and histopathological changes of standard organs and tissues. The highest dose tested in the 13-week study (3783 and 4396mg/kgbw/d for males and females, respectively) proved to be a NOAEL.

  4. Modifying theophylline microparticle surfaces via the sequential deposition of poly(vinyl alcohol-co-vinyl acetate) copolymers.

    PubMed

    Zhao, Yanjun; Alas'ad, Mannar A; Jones, Stuart A

    2014-03-10

    The aim of this study was to investigate the manner in which amphiphilic poly(vinyl alcohol-co-vinyl acetate) copolymers (PVA-Ac) assembled on drug surfaces and use this information to generate a novel bi-layer polymer coating for a theophylline microparticle. Three grades of PVA-Ac, differing in hydrolysis degree and monomer distribution, were synthesised, characterised by nuclear magnetic resonance and shown to interact with theophylline when suspended in water. PVA-Ac deposition at the solid/liquid interface was driven by polymer hydrogen bond formation in a process that induced consequential structural changes in the macromolecule architecture. The most hydrophobic grades of the copolymer appeared to adsorb in a multistage process that passed through a series of equilibrium points. The PVA-Ac surface allowed two grades of the copolymer to be sequentially adsorbed and this resulted in the fabrication of a microparticle with desirable characteristics for pharmaceutical formulation production.

  5. Photothermal degradation of ethylene/vinylacetate copolymer

    NASA Technical Reports Server (NTRS)

    Liang, R. H.; Chung, S.; Clayton, A.; Di Stefano, S.; Oda, K.; Hong, S. D.; Gupta, A.

    1983-01-01

    Photothermal degradation studies were conducted on a 'stabilized' formulation of ethylene/vinyl acetate copolymer (EVA) in the temperature range 25-105 C under three different oxygen environments (in open air, with limited access to O2, and in a dark closed stagnant oven). These studies were performed in order to evaluate the utility of EVA as an encapsulation material for photovoltaic modules. Results showed that at low temperature (25 C), slow photooxidation of the polymer occurred via electronic energy transfer involving the UV absorber incorporated in the polymer. However, no changes in the physical properties of the bulk polymer were detected up to 1500 hours of irradiation. At elevated temperatures, leaching and evaporation of the additives occurred, which ultimately resulted in the chemical crosslinking of the copolymer and the formation of volatile photoproducts such as acetic acid.

  6. Thermal Conductivity of Ethylene Vinyl Acetate Copolymer/Carbon Nanofiller Blends

    NASA Technical Reports Server (NTRS)

    Ghose, S.; Watson, K. A.; Working, D. C.; Connell, J. W.; Smith, J. G., Jr.; Lin, Y.; Sun, Y. P.

    2007-01-01

    To reduce weight and increase the mobility, comfort, and performance of future spacesuits, flexible, thermally conductive fabrics and plastic tubes are needed for the Liquid Cooling and Ventilation Garment. Such improvements would allow astronauts to operate more efficiently and safely for extended extravehicular activities. As an approach to raise the thermal conductivity (TC) of an ethylene vinyl acetate copolymer (Elvax 260), it was compounded with three types of carbon based nanofillers: multi-walled carbon nanotubes (MWCNTs), vapor grown carbon nanofibers (CNFs), and expanded graphite (EG). In addition, other nanofillers including metallized CNFs, nickel nanostrands, boron nitride, and powdered aluminum were also compounded with Elvax 260 in the melt at various loading levels. In an attempt to improve compatibility between Elvax 260 and the nanofillers, MWCNTs and EG were modified by surface coating and through noncovalent and covalent attachment of organic molecules containing alkyl groups. Ribbons of the nanocomposites were extruded to form samples in which the nanofillers were aligned in the direction of flow. Samples were also fabricated by compression molding to yield nanocomposites in which the nanofillers were randomly oriented. Mechanical properties of the aligned samples were determined by tensile testing while the degree of dispersion and alignment of nanoparticles were investigated using high-resolution scanning electron microscopy. TC measurements were performed using a laser flash (Nanoflash ) technique. TC of the samples was measured in the direction of, and perpendicular to, the alignment direction. Additionally, tubing was also extruded from select nanocomposite compositions and the TC and mechanical flexibility measured.

  7. Evaluation of CO2-philicity of poly(vinyl acetate) and poly(vinyl acetate-alt-maleate) copolymers through molecular modeling and dissolution behavior measurement.

    PubMed

    Hu, Dongdong; Sun, Shaojun; Yuan, Peiqing; Zhao, Ling; Liu, Tao

    2015-02-19

    Multiscale molecular modeling and dissolution behavior measurement were both used to evaluate the factors conclusive on the CO2-philicity of poly(vinyl acetate) (PVAc) homopolymer and poly(vinyl acetate-alt-maleate) copolymers. The ab initio calculated interaction energies of the candidate CO2-philic molecule models with CO2, including vinyl acetate dimer (VAc), dimethyl maleate (DMM), diethyl maleate (DEM), and dibutyl maleate (DBM), showed that VAc was the most CO2-philc segment. However, the cohesive energy density, solubility parameter, Flory-Huggins parameter, and radial distribution functions calculated by using the molecular dynamics simulations for the four polymer and polymer-CO2 systems indicated that poly(VAc-alt-DBM) had the most CO2-philicity. The corresponding polymers were synthesized by using free radical polymerization. The measurement of cloud point pressures of the four polymers in CO2 also demonstrated that poly(VAc-alt-DBM) had the most CO2-philicity. Although copolymerization of maleate, such as DEM or DBM, with PVAc reduced the polymer-CO2 interactions, the weakened polymer-polymer interaction increased the CO2-philicity of the copolymers. The polymer-polymer interaction had a significant influence on the CO2-philicity of the polymer. Reduction of the polymer-polymer interaction might be a promising strategy to prepare the high CO2-philic polymers on the premise that the strong polymer-CO2 interaction could be maintained.

  8. Effect of VA and MWNT contents on the rheological and physical properties of EVA

    NASA Astrophysics Data System (ADS)

    Kim, Jong-Ho; Lee, Seungwon; Kim, Byoung Chul; Shin, Bong-Seob; Jeon, Jong-Young; Chae, Dong Wook

    2016-02-01

    Ethylene vinyl acetate (EVA) copolymers with two different VA contents (15 and 33 wt.%, denoted by EVA15 and EVA33, respectively) were melt compounded with multi-walled carbon nanotubes (MWNTs) and the effect of VA and nanotube contents on the rheological, thermal and morphological properties was investigated. The addition of nanotubes into both EVAs increased the onset temperature of crystallization and broadened the peak, but further addition from 3 wt.% slightly decreased the temperature with increasing nanotube contents. In the wide angle X-ray diffraction patterns the peak of EVA15 was little affected by the presence of nanotubes but that of EVA33 slightly shifted to higher degree and became sharper with increasing nanotube contents. Dynamic viscosity (η') increased with nanotube contents giving abrupt increase at 2 wt.% nanotubes. Loss tangent decreased with increasing nanotube contents exhibiting the plateau-like behavior over most of the frequency range from 2 wt.% nanotubes. In the Casson plot, yield stress increased with nanotube content and its increasing extent was more notable for more VA content. In the Cole-Cole plot, the presence of nanotubes from 2 wt.% gave rise to the deviation from the single master curve by decreasing the slope. The deviated extent of EVA33 became more remarkable with increasing nanotube contents than that of EVA15. The stress-strain curve showed that more improved tensile modulus and yield stress were achieved by the introduction of MWNTs for EVA 33 than for EVA15. Tensile strength of EVA33 increased with increasing nanotube contents, while that of EVA15 decreased.

  9. EVA Requirements for Exploration EVAs

    NASA Technical Reports Server (NTRS)

    Webbon, Bruce; Luna, Bernadette

    2005-01-01

    The exploration program proposed by the President will require extensive extravehicular operations in a wide range of environments. These include Og EVAs in planetary orbits as well as potential contingency EVAs during inter-planetary flight and surface operations on the moon and Mars. The EVA environments and mission requirements are very different for each of these. Commonality among such systems is highly desirable from the programmatic standpoint but the dramatic differences in EVA environments will have a profound impact on EVA system design. This paper will examine the relevant environmental parameters and discuss their impacts on EVA system design. An EVA design philosophy that maximizes EVA system commonality will be discussed.

  10. The effect of the Nb2O5 dispersion on ethylene vinyl acetate to obtain ethylene vinyl acetate/Nb2O5 nanostructured materials.

    PubMed

    Valentim, Ana Claudia S; Tavares, Maria Inês Bruno; da Silva, Emerson Oliveira

    2013-06-01

    This work investigated the effect of niobium pentoxide nanoparticles (Nb2O5) on the molecular organization of an ethylene vinyl acetate copolymer (EVA) matrix containing 28% vinyl acetate groups, according to their dispersion and distribution in the polymer matrix. Due to niobium pentoxide's characteristics and properties, it may interfere in the chemical and UV resistance, as well as in the EVA mechanical properties, increasing mechanical resistance. The EVA/Nb2O5 nanocomposite films, with Nb2O5 varying from 0.25 to 1% in relation to the total EVA mass, were prepared by solution casting. The Nb2O5 was well dispersed with the use of ultrasound. These films were mainly characterized by X-ray diffraction and low-field nuclear magnetic resonance through relaxometry, in order to obtain responses on the structural organization and molecular dynamic, respectively, and consequently to understand the effect of the nanoparticles on the EVA matrix. The results showed that the addition of Nb2O5 to the EVA matrix caused changes in its crystallinity and molecular mobility, due to the new interactions formed by the good dispersion of nanoparticles and also their distribution in the EVA matrix, changing the copolymer characteristics due to the formation of a new material.

  11. Bioconversion of glycerine pitch into a novel yellow-pigmented P(3HB-co-4HB) copolymer: synergistic effect of ammonium acetate and polymer characteristics.

    PubMed

    Ramachandran, Hema; Amirul, A A

    2014-01-01

    Glycerine pitch waste generated from oleochemical industry was exploited as a carbon source for poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-co-4HB)) copolymer production by a novel, yellow-pigmented bacterium Cupriavidus sp. USMAHM13 to improve the economics of microbial polyhydroxyalkanoate production and to establish a feasible waste management approach. Medium optimization using response surface methodology through shake-flask fermentation had led to the accumulation of P(3HB-co-51%4HB) copolymer using a combination of glycerine pitch (10 g/l), 1,4-butanediol (8.14 g/l), and ammonium acetate (2.39 g/l). P(3HB-co-4HB) copolymers with 4HB monomer compositions ranged from 3 to 40 mol% were obtained through batch fermentation in a bioreactor using different concentrations of ammonium acetate. The copolymers exhibited a wide range of material properties depending on the monomer composition and type of carbon sources. P(3HB-co-40%4HB) was a typical random copolymer, whereas other P(3HB-co-4HB) produced were blend copolymers. Carotenoid pigment which was produced simultaneously with the polymer production was found to have negligible effect on the mechanical and thermal properties of the P(3HB-co-4HB) copolymer films.

  12. Irradiation crosslinking and halogen-free flame retardation of EVA using hydrotalcite and red phosphorus

    NASA Astrophysics Data System (ADS)

    Jiao, Chuanmei; Wang, Zhengzhou; Chen, Xilei; Yu, Benyi; Hu, Yuan

    2006-05-01

    Halogen-free flame retarded ethylene vinyl acetate copolymer (EVA) composites using Mg-Al-CO 3 hydrotalcite (MALDH) and microcapsulated red phosphorus (MRP) have been prepared in a melt process. The flame retardation of the composites has been studied by the limited oxygen index (LOI) and UL-94 methods, and the thermal decomposition by the thermogravimetric analysis (TGA). The changes of their properties of the composites before and after the Gamma irradiation are compared. The synergistic effect in the flame retardation between MALDH and MRP in EVA has been found. The EVA/MALDH/MRP composites after the irradiation crosslinking result in a great increase in the Vicat softening point. The LOI value, the mechanical properties and thermal stability are also improved for the composites irradiated by a suitable irradiation dose.

  13. Effect of cellulose whisker content on the properties of poly(ethylene-co-vinyl acetate)/cellulose composites.

    PubMed

    Elanthikkal, Silviya; Gopalakrishnapanicker, Unnikrishnan; Varghese, Soney; Guthrie, James T; Francis, Tania

    2013-06-20

    The reinforcing effect of cellulose whiskers, produced from banana waste fibres, has been investigated using poly(ethylene-co-vinyl acetate) [EVA]/cellulose whisker composites. Cellulose whiskers, approximately 300 nm long and 30 nm wide, were obtained via a sulphuric acid hydrolysis method. The effects of the cellulose whisker loading on the thermal properties, mechanical properties and on the morphological features of the composites have been investigated. EVA copolymer with a vinyl acetate segment content of 40% has been used for composite fabrication. The developed composites showed superior thermal and mechanical properties relative to that of the EVA copolymer alone. Three theoretical models, namely the Halpin-Tsai model, the Kerner model and the Nicolais-Narkis model have been employed to provide a basis for the comparison of the results with the observations from the tensile investigations.

  14. Poly vinyl acetate and ammonio methacrylate copolymer as unconventional polymer blends increase the mechanical robustness of HPMC matrix tablets.

    PubMed

    Ali, R; Dashevsky, A; Bodmeier, R

    2017-01-10

    The objective was to investigate poly vinyl acetate (Kollicoat(®) SR 30 D) and ammonio methacrylate copolymer (Eudragit(®) RL 30 D) blends as coatings to increase the mechanical robustness of hydroxypropyl methylcellulose (HPMC) matrix tablets. Poly vinyl acetate (Kollicoat(®) SR 30 D - KSR) was selected for its flexibility and ammonio methacrylate copolymer (Eudragit(®) RL 30 D - ERL) because of its high permeability. Films based on KSR:ERL blends were prepared by casting or spraying aqueous dispersions of these polymers and were characterized by water uptake, dry mass loss and mechanical properties. KSR:ERL blends were investigated as coating materials to improve the robustness, mechanical strength and drug release from the HPMC matrix tablets containing propranolol HCl, caffeine and carbamazepine as model drugs. Both HPMC and the polymer coating affected the propranolol release. The release and the mechanical properties could be easily adjusted by varying the polymer blend ratio. The flexibility increased with increasing KSR content. At an 8% w/w coating level, a force of 3.2N was required to rupture the coating of the swollen tablet after 16h in the release medium; the coated tablets were thus robust to withstand gastrointestinal forces. The coating level (6%-10%, w/w) and dissolution agitation rate (50rpm to 150rpm) had no effect on the drug release. The water-insoluble carbamazepine was not released from the coated tablets as HPMC erosion, which is necessary for the release of a poorly water-soluble drug was hindered by the coating. The release of the water-soluble propranolol increased with increasing drug content and decreased with increasing HPMC content.

  15. Effect of addition of coal-tar pitches on adhesive properties of copolymer of ethylene with vinyl acetate

    SciTech Connect

    Chernikov, O.I.; Mironov, V.A.; Mitrokhina, L.L.; Kuznetsova, L.S.; Nepomnyashchaya, A.S.; Kachan, A.A.

    1984-08-01

    Results of studies of the effect of the addition of coal-tar pitches on the water resistance and adhesive properties of the copolymer of ethylene with vinyl acetate (CEVA) used as an adhesive layer in polymer films for protection of oil and gas pipelines against corrosion are presented. The dependence of the adhesive strength of CEVA with 12% vinyl acetate (VA) on the concentration of coal-tar pitch additives with softening temperatures of 70, 85, and 107/sup 0/C was found to be extreme with maximum adhesive strength in the concentration range of 0.8-1.4%. This increase in adhesive strength at low concentrations is thought to be due to improvement in the wetability of the melt. After long exposure (30h) to boiling water, the water resistance of the adhesive joints was improved by the addition of coal-tar pitches; but in the initial period of boiling, a decrease in water resistance was produced by the addition of coal-tar pitches. Films with pitch additives with a softening temperature of 70/sup 0/C were noted to have the highest hydrophobicity at low concentrations of the pitch additive.

  16. Heat shrinkage of electron beam modified EVA

    NASA Astrophysics Data System (ADS)

    Datta, Sujit K.; Chaki, T. K.; Tikku, V. K.; Pradhan, N. K.; Bhowmick, A. K.

    1997-10-01

    Heat shrinkage of electron beam modified ethylene vinyl acetate copolymer (EVA) has been investigated over a range of times, temperatures, stretching, irradiation doses and trimethylolpropane trimethacrylate (TMPTMA) levels. The irradiated (radiation dose 50 kGy and TMPTMA level 1%) and stretched (100% elongation) sample shrinks to a maximum level when kept at 453K temperature for 60 s. The heat shrinkage of samples irradiated with radiation doses of 20, 50, 100 and 150 kGy increases sharply with increasing stretching in the initial stage. Amnesia rating decreases with increasing radiation dose and TMPTMA level as well as gel content. The high radiation dose and TMPTMA level lower the heat shrinkage due to the chain scission. The effect of temperature at which extension is carried out on heat shrinkage is marginal. The irradiated (radiation dose 50 kGy and TMPTMA level 1%) EVA tubes of different dimensions expanded in a laboratory grade tube expander show similar behaviour at 453K and 60 s. The X-ray and DSC studies reveal that the crystallinity increases on stretching due to orientation of chains and it decreases to a considerable extent on heat shrinking. The theoretical and experimental values of heat shrinkage for tubes and rectangular strips are in good accord, when the radiation dose is 50 kGy and TMPTMA level 1%.

  17. Glatiramer Acetate in Treatment of Multiple Sclerosis: A Toolbox of Random Co-Polymers for Targeting Inflammatory Mechanisms of both the Innate and Adaptive Immune System?

    PubMed Central

    Jalilian, Babak; Einarsson, Halldór Bjarki; Vorup-Jensen, Thomas

    2012-01-01

    Multiple sclerosis is a disease of the central nervous system, resulting in the demyelination of neurons, causing mild to severe symptoms. Several anti-inflammatory treatments now play a significant role in ameliorating the disease. Glatiramer acetate (GA) is a formulation of random polypeptide copolymers for the treatment of relapsing-remitting MS by limiting the frequency of attacks. While evidence suggests the influence of GA on inflammatory responses, the targeted molecular mechanisms remain poorly understood. Here, we review the multiple pharmacological modes-of-actions of glatiramer acetate in treatment of multiple sclerosis. We discuss in particular a newly discovered interaction between the leukocyte-expressed integrin αMβ2 (also called Mac-1, complement receptor 3, or CD11b/CD18) and perspectives on the GA co-polymers as an influence on the function of the innate immune system. PMID:23203082

  18. Development and characterization of poly(1-vinylpyrrolidone-co-vinyl acetate) copolymer based polymer electrolytes.

    PubMed

    Sa'adun, Nurul Nadiah; Subramaniam, Ramesh; Kasi, Ramesh

    2014-01-01

    Gel polymer electrolytes (GPEs) are developed using poly(1-vinylpyrrolidone-co-vinyl acetate) [P(VP-co-VAc)] as the host polymer, lithium bis(trifluoromethane) sulfonimide [LiTFSI] as the lithium salt and ionic liquid, and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide [EMImTFSI] by using solution casting technique. The effect of ionic liquid on ionic conductivity is studied and the optimum ionic conductivity at room temperature is found to be 2.14 × 10(-6) S cm(-1) for sample containing 25 wt% of EMImTFSI. The temperature dependence of ionic conductivity from 303 K to 353 K exhibits Arrhenius plot behaviour. The thermal stability of the polymer electrolyte system is studied by using thermogravimetric analysis (TGA) while the structural and morphological properties of the polymer electrolyte is studied by using Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction analysis (XRD), respectively.

  19. EVA Physiology

    NASA Video Gallery

    An introduction to the risk of decompression sickness (DCS) in astronauts during EVA. This will include an explanation of Prebreathe Protocols (PB), to affect nitrogen washout as a primary risk mit...

  20. Development and Characterization of Poly(1-vinylpyrrolidone-co-vinyl acetate) Copolymer Based Polymer Electrolytes

    PubMed Central

    Sa'adun, Nurul Nadiah; Subramaniam, Ramesh; Kasi, Ramesh

    2014-01-01

    Gel polymer electrolytes (GPEs) are developed using poly(1-vinylpyrrolidone-co-vinyl acetate) [P(VP-co-VAc)] as the host polymer, lithium bis(trifluoromethane) sulfonimide [LiTFSI] as the lithium salt and ionic liquid, and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide [EMImTFSI] by using solution casting technique. The effect of ionic liquid on ionic conductivity is studied and the optimum ionic conductivity at room temperature is found to be 2.14 × 10−6 S cm−1 for sample containing 25 wt% of EMImTFSI. The temperature dependence of ionic conductivity from 303 K to 353 K exhibits Arrhenius plot behaviour. The thermal stability of the polymer electrolyte system is studied by using thermogravimetric analysis (TGA) while the structural and morphological properties of the polymer electrolyte is studied by using Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction analysis (XRD), respectively. PMID:25431781

  1. Incorporation of nisin in poly (ethylene-co-vinyl acetate) films by melt processing: a study on the antimicrobial properties.

    PubMed

    Scaffaro, Roberto; Botta, Luigi; Marineo, Sandra; Puglia, Anna Maria

    2011-07-01

    Both industry and academia have shown a growing interest in materials with antimicrobial properties suitable for food packaging applications. In this study, we prepared and characterized thin films of ethylene-co-vinyl acetate (EVA) copolymer with antimicrobial properties. The films were prepared with a film blowing process by incorporating a nisin preparation as an antimicrobial agent in the melt. Two grades of EVA containing 14 and 28% (wt/wt) vinyl acetate (EVA 14 and EVA 28, respectively) and two commercial formulations of nisin with different nominal activities were used. The effect of the nisin concentration also was evaluated. The films with the highest antimicrobial activity were those formulated with nisin at the highest activity and EVA with the highest content of vinyl acetate. The use of the commercial formulation of nisin with high activity in the EVA films allowed reduction in the amount of nisin needed to provide antimicrobial properties. Consequently, the mechanical properties of these films were only slightly inferior to those of the pure polymers. In contrast, films prepared by incorporating more of the nisin with lower activity had poor mechanical properties. The effect of different processing temperatures used in the preparation of the films on the antimicrobial properties of the films also was evaluated. The materials displayed antimicrobial properties even when they were prepared at temperatures as high as 160 °C, probably because of the very short processing time (60 to 90 s) required for preparation.

  2. Pyrolysis-gas chromatography-mass spectrometry for studying N-vinyl-2-pyrrolidone-co-vinyl acetate copolymers and their dissolution behaviour.

    PubMed

    Chojnacka, Aleksandra; Ghaffar, Abdul; Feilden, Andrew; Treacher, Kevin; Janssen, Hans-Gerd; Schoenmakers, Peter

    2011-11-14

    Knowledge on the solubility behaviour and dissolution rate of speciality and commodity polymers is very important for the use of such materials in high-tech applications. We have developed methods for the quantification and characterization of dissolved copolymers of N-vinyl-2-pyrrolidone (VP) and vinyl acetate (VA) during dissolution in water. The methods are based on pyrolysis (Py) performed in a programmed-temperature vaporization injector with subsequent identification and quantification of the components in the pyrolysate using capillary gas chromatography-mass spectrometry (GC-MS). By injecting large volumes and applying cryo-focussing at the top of the column, low detection limits could be achieved. The monomer ratio was found to have the greatest effect on the dissolution rate of the PVP-co-VA copolymers. The material with the highest amount of VA (50%) dissolves significantly slower than the other grades. Size-exclusion chromatography (SEC) and Py-GC-MS were used to measure molecular weights and average chemical compositions, respectively. Combined off-line SEC//Py-GC-MS was used to determine the copolymer composition (VP/VA ratio), as a function of the molecular weight for the pure polymers. In the dissolution experiments, a constant VP/VA ratio across the dissolution curve was observed for all copolymers analysed. This suggests a random distribution of the two monomers over the molecules.

  3. Relationship between cross-linking conditions of ethylene vinyl acetate and potential induced degradation for crystalline silicon photovoltaic modules

    NASA Astrophysics Data System (ADS)

    Jonai, Sachiko; Hara, Kohjiro; Tsutsui, Yuji; Nakahama, Hidenari; Masuda, Atsushi

    2015-08-01

    In this study, we investigated the relationship in crystalline silicon (c-Si) photovoltaic (PV) modules between the cross-linking level of copolymer of ethylene and vinyl acetate (EVA) as the encapsulant and the degree of degradation due to potential induced degradation (PID) phenomenon. We used three methods for the determination of cross-linking level of EVA: xylene method, which is one of the solvent extraction methods (SEM), curing degree by differential scanning calorimetry (DSC), and viscoelastic properties by dynamic mechanical analysis (DMA). The results indicate that degradation of PV modules by PID test depends on the cross-linking level of EVA. The PV modules encapsulated by EVA with higher cross-linking level show lower degradation degree due to PID phenomenon. Also we showed that EVA with higher cross-linking level tended to be higher volume resistivity. This tendency is similar to that for electrical resistance value during the PID test. The PID test was also done by changing thickness of EVA between front cover glass and c-Si with the same cross-linking level. The PV modules encapsulated by thicker EVA between front cover glass and c-Si cell show lower degradation by PID. From these results, the PV modules encapsulated by EVA with higher cross-linking level, higher volume resistivity and increased thickness would be tolerant of PID phenomenon.

  4. [Prediction of Encapsulation Temperatures of Copolymer Films in Photovoltaic Cells Using Hyperspectral Imaging Techniques and Chemometrics].

    PubMed

    Lin, Ping; Chen, Yong-ming; Yao, Zhi-lei

    2015-11-01

    A novel method of combination of the chemometrics and the hyperspectral imaging techniques was presented to detect the temperatures of Ethylene-Vinyl Acetate copolymer (EVA) films in photovoltaic cells during the thermal encapsulation process. Four varieties of the EVA films which had been heated at the temperatures of 128, 132, 142 and 148 °C during the photovoltaic cells production process were used for investigation in this paper. These copolymer encapsulation films were firstly scanned by the hyperspectral imaging equipment (Spectral Imaging Ltd. Oulu, Finland). The scanning band range of hyperspectral equipemnt was set between 904.58 and 1700.01 nm. The hyperspectral dataset of copolymer films was randomly divided into two parts for the training and test purpose. Each type of the training set and test set contained 90 and 10 instances, respectively. The obtained hyperspectral images of EVA films were dealt with by using the ENVI (Exelis Visual Information Solutions, USA) software. The size of region of interest (ROI) of each obtained hyperspectral image of EVA film was set as 150 x 150 pixels. The average of reflectance hyper spectra of all the pixels in the ROI was used as the characteristic curve to represent the instance. There kinds of chemometrics methods including partial least squares regression (PLSR), multi-class support vector machine (SVM) and large margin nearest neighbor (LMNN) were used to correlate the characteristic hyper spectra with the encapsulation temperatures of of copolymer films. The plot of weighted regression coefficients illustrated that both bands of short- and long-wave near infrared hyperspectral data contributed to enhancing the prediction accuracy of the forecast model. Because the attained reflectance hyperspectral data of EVA materials displayed the strong nonlinearity, the prediction performance of linear modeling method of PLSR declined and the prediction precision only reached to 95%. The kernel-based forecast models were

  5. Crystallization of Ethylene Vinyl Acetate (EVA) and Polyethylene (PE) /deuterated Polystyrene (dPS) Blends in Supercritical Carbon Dioxide (scCO2)

    NASA Astrophysics Data System (ADS)

    Pynn, Christopher; Ahdout, Payvand; Jerome, John; Wang, Yantian; Zaitsev, Vladimir; Soklov, Johnathan; Rafailovich, Miriam; Schwarz, Steven

    2006-03-01

    Thin films of EVA or PE and dPS were spun cast onto Si wafers and crystallized in supercritical carbon dioxide at pressures and temperatures corresponding to the density fluctuation ridge^1 or thermally annealed using standard protocols. The morphology composition and melting points of the films were studied using scanning force microscopy and imaging time-of-flight secondary ion mass spectrometry as function of film thickness and homopolymer concentration. The results showed that exposure to scCO2 produced highly crystalline films. Furthermore, in contrast to the thermally annealed films, the homopolymer was fully incorporated into the crystalline phase. The surface morphology of the films after crystallization showed either island or hole structure, depending on the relation between the film thickness and the lamellar height. Supported in part by the NSF-MRSEC program and by a grant from the SRC-NYS consortium. Reference: ^1 Koga T., Seo Y.S., Shin K., Zhang Y., Rafailovich M., Sokolov J., B. Chu, Satija, S.K. Macromolecules. Vol. 36. 2003: 5236- 5243.

  6. Risk Management in EVA

    NASA Technical Reports Server (NTRS)

    Hall, Jonathan; Lutomski, M.

    2006-01-01

    This viewgraph presentation reviews the use of risk management in Extravehicular Activities (EVA). The contents include: 1) EVA Office at NASA - JSC; 2) EVA Project Risk Management: Why and When; 3) EVA Office Risk Management: How; 4) Criteria for Closing a Risk; 5) Criteria for Accepting a Risk; 6) ISS IRMA Reference Card Data Entry Requirement s; 7) XA/ EVA Office Risk Activity Summary; 8) EVA Significant Change Summary; 9) Integrated Risk Management Application (XA) Matrix, March 31, 2004; 10) ISS Watch Item: 50XX Summary Report; and 11) EVA Project RM Usefulness

  7. Influence of mechanical stimulation in the development of a medial equivalent tissue-engineered vascular construct using a gelatin-g-vinyl acetate co-polymer scaffold.

    PubMed

    Thomas, Lynda V; Nair, Prabha D

    2012-01-01

    Vascular regeneration in the area of small diameter (<6 mm) vessels via the tissue-engineering approach has been in focus for some time now. In this study, we report the development and evaluation of a tissue-engineered medial equivalent using gelatin-g-vinyl acetate co-polymer (GeVAc) as the scaffold material. GeVAc was synthesized by co-polymerizing gelatin and vinyl acetate monomer in the presence of AIBN as the initiator and subjected to physico-chemical characterization. A porous 3-D scaffold with open interconnected pores was then produced from GeVAc. The scaffold is non-cytotoxic with good smooth muscle cell proliferative capacity and high cell viability. Influence of smooth muscle cell phenotype in response to these scaffolds has been studied under mechanical stimulation. It was found that the cell-seeded tubular GeVAc constructs under mechanical stimulation preferentially supported the contractile phenotype of smooth muscle cells, as evidenced by the elevated expression of contractile protein markers such as alpha-SMA, calponin and SM22α. The mechanical properties and the ECM secretion were also increased on applying the mechanical stimulation. Hence, the results showed the promising potential of the GeVAc scaffolds in the regeneration of the medial equivalent tissue-engineered vascular construct.

  8. Transparent nanostructured cellulose acetate films based on the self assembly of PEO-b-PPO-b-PEO block copolymer.

    PubMed

    Gutierrez, Junkal; Carrasco-Hernandez, Sheyla; Barud, Hernane S; Oliveira, Rafael L; Carvalho, Renata A; Amaral, André C; Tercjak, Agnieszka

    2017-06-01

    In this study fabrication and characterization of transparent nanostructured composite films based on cellulose triacetate (CTA) and poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (EPE) triblock copolymer were presented. The effect of the addition of EPE triblock copolymer on the thermal stability, morphology, and mechanical properties of cellulose triacetate films was investigated. The triblock EPE was chosen since PEO blocks interact favorably with CTA, whereas, PPO blocks remain immiscible which provokes a microphase separation. This allows to obtain EPE/CTA composite films with ordered microphase-separated structures where PPO spherical microdomains are well-dispersed in PEO/CTA matrix by simple solvent-evaporation process. During this process, PEO block chains selectively interact with CTA by strong interpolymer hydrogen-bonding while PPO block microseparated. The addition even 40wt% of EPE leads to nanostructured EPE/CTA composite. The cytotoxicity assay of CTA and EPE/CTA composite films confirm non-toxic character of designed transparent nanostructured composites based on sustainable matrices.

  9. Fast quantifying collision strength index of ethylene-vinyl acetate copolymer coverings on the fields based on near infrared hyperspectral imaging techniques

    PubMed Central

    Chen, Y. M.; Lin, P.; He, Y.; He, J. Q.; Zhang, J.; Li, X. L.

    2016-01-01

    A novel strategy based on the near infrared hyperspectral imaging techniques and chemometrics were explored for fast quantifying the collision strength index of ethylene-vinyl acetate copolymer (EVAC) coverings on the fields. The reflectance spectral data of EVAC coverings was obtained by using the near infrared hyperspectral meter. The collision analysis equipment was employed to measure the collision intensity of EVAC materials. The preprocessing algorithms were firstly performed before the calibration. The algorithms of random frog and successive projection (SP) were applied to extracting the fingerprint wavebands. A correlation model between the significant spectral curves which reflected the cross-linking attributions of the inner organic molecules and the degree of collision strength was set up by taking advantage of the support vector machine regression (SVMR) approach. The SP-SVMR model attained the residual predictive deviation of 3.074, the square of percentage of correlation coefficient of 93.48% and 93.05% and the root mean square error of 1.963 and 2.091 for the calibration and validation sets, respectively, which exhibited the best forecast performance. The results indicated that the approaches of integrating the near infrared hyperspectral imaging techniques with the chemometrics could be utilized to rapidly determine the degree of collision strength of EVAC. PMID:26875544

  10. Fast quantifying collision strength index of ethylene-vinyl acetate copolymer coverings on the fields based on near infrared hyperspectral imaging techniques.

    PubMed

    Chen, Y M; Lin, P; He, Y; He, J Q; Zhang, J; Li, X L

    2016-02-15

    A novel strategy based on the near infrared hyperspectral imaging techniques and chemometrics were explored for fast quantifying the collision strength index of ethylene-vinyl acetate copolymer (EVAC) coverings on the fields. The reflectance spectral data of EVAC coverings was obtained by using the near infrared hyperspectral meter. The collision analysis equipment was employed to measure the collision intensity of EVAC materials. The preprocessing algorithms were firstly performed before the calibration. The algorithms of random frog and successive projection (SP) were applied to extracting the fingerprint wavebands. A correlation model between the significant spectral curves which reflected the cross-linking attributions of the inner organic molecules and the degree of collision strength was set up by taking advantage of the support vector machine regression (SVMR) approach. The SP-SVMR model attained the residual predictive deviation of 3.074, the square of percentage of correlation coefficient of 93.48% and 93.05% and the root mean square error of 1.963 and 2.091 for the calibration and validation sets, respectively, which exhibited the best forecast performance. The results indicated that the approaches of integrating the near infrared hyperspectral imaging techniques with the chemometrics could be utilized to rapidly determine the degree of collision strength of EVAC.

  11. Fast quantifying collision strength index of ethylene-vinyl acetate copolymer coverings on the fields based on near infrared hyperspectral imaging techniques

    NASA Astrophysics Data System (ADS)

    Chen, Y. M.; Lin, P.; He, Y.; He, J. Q.; Zhang, J.; Li, X. L.

    2016-02-01

    A novel strategy based on the near infrared hyperspectral imaging techniques and chemometrics were explored for fast quantifying the collision strength index of ethylene-vinyl acetate copolymer (EVAC) coverings on the fields. The reflectance spectral data of EVAC coverings was obtained by using the near infrared hyperspectral meter. The collision analysis equipment was employed to measure the collision intensity of EVAC materials. The preprocessing algorithms were firstly performed before the calibration. The algorithms of random frog and successive projection (SP) were applied to extracting the fingerprint wavebands. A correlation model between the significant spectral curves which reflected the cross-linking attributions of the inner organic molecules and the degree of collision strength was set up by taking advantage of the support vector machine regression (SVMR) approach. The SP-SVMR model attained the residual predictive deviation of 3.074, the square of percentage of correlation coefficient of 93.48% and 93.05% and the root mean square error of 1.963 and 2.091 for the calibration and validation sets, respectively, which exhibited the best forecast performance. The results indicated that the approaches of integrating the near infrared hyperspectral imaging techniques with the chemometrics could be utilized to rapidly determine the degree of collision strength of EVAC.

  12. Studies Relating to EVA

    NASA Technical Reports Server (NTRS)

    1997-01-01

    In this session, Session JA1, the discussion focuses on the following topics: The Staged Decompression to the Hypobaric Atmosphere as a Prophylactic Measure Against Decompression Sickness During Repetitive EVA; A New Preoxygenation Procedure for Extravehicular Activity (EVA); Metabolic Assessments During Extra-Vehicular Activity; Evaluation of Safety of Hypobaric Decompressions and EVA From Positions of Probabilistic Theory; Fatty Acid Composition of Plasma Lipids and Erythrocyte Membranes During Simulation of Extravehicular Activity; Biomedical Studies Relating to Decompression Stress with Simulated EVA, Overview; The Joint Angle and Muscle Signature (JAMS) System - Current Uses and Future Applications; and Experimental Investigation of Cooperative Human-Robotic Roles in an EVA Work Site.

  13. In situ electron microscopy of Braille microsystems: photo-actuation of ethylene vinyl acetate/carbon nanotube composites

    NASA Astrophysics Data System (ADS)

    Czaniková, Klaudia; Krupa, Igor; Račko, Dušan; Šmatko, Vasilij; Campo, Eva M.; Pavlova, Ewa; Omastová, Mária

    2015-02-01

    The development of new types of tactile displays based on the actuation of composite materials can aid the visually impaired. Micro/nano systems based on ethylene vinyl acetate (EVA) polymeric matrices enriched with multiwalled carbon nanotubes (MWCNT) can produce ensembles capable of light-induced actuation. In this report, we investigate two types of commercial EVA copolymers matrices containing 28 and 50 wt% vinyl-acetate (VA). Non-covalent modification of carbon nanotubes was achieved through a compatibilization technique that appends the pyrenenyl and cholesteryl groups on the carbon nanotubes (CNTs) surface. EVA/MWCNT nanocomposites were prepared by casting from a solution. These composites were shaped into Braille elements using molds. The deformation of the Braille element (BE) under light-emitting diode (LED) illumination was observed for the first time by in situ scanning electron microscopy (SEM). The superior actuation performance promoted by the EVA/MWCNT nanocomposites indicates that these materials will be useful in the future as light-driven micro/nano system actuators.

  14. Effect of polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer on bioadhesion and release rate property of eplerenone pellets.

    PubMed

    Kendre, Prakash Namdeo; Chaudhari, Pravin Digambar

    2017-05-01

    The present study involved the design and development of oral bioadhesive pellets of eplerenone. A solid dispersion of eplerenone was developed with a hydrophilic carrier, polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (Soluplus(®)). Bioadhesive pellets were prepared from this solid dispersion using a combination of HPMC K4M and Carbopol 934P. Both the solid dispersion and the pellets were evaluated for various physicochemical properties such as solubility, entrapment efficiency, drug content, surface morphology, mucoadhesion and swelling behavior. Analysis carried out using FT-IR, DSC and XRD found no interaction between the eplerenone and excipients. The solid dispersion had irregular-shaped smooth-surfaced particles of diameter 265 ± 105.5 μm. In TEM analysis, eplerenone particles of size 79-120 nm were found. The solubility and dissolution of eplerenone in the Soluplus(®)-based solid dispersion were 5.26 and 2.50 times greater, respectively. Investigation of the swelling behavior of the pellets showed that the thickness of the gel layer increased continuously over the duration of the study. Moreover, a correlation was observed between the thickness and strength of the gel layer and the percentage release. The mechanism of drug release was found to be non-Fickian (anomalous), with the release kinetics approaching first-order kinetics. The bioavailability of the eplerenone bioadhesive pellet formulation was studied using Wistar rats and was found to be improved. An in vivo mucoadhesion study showed that the pellets are retained for 24 h in rabbits. It was concluded that Soluplus(®) had a positive effect on the solubility and dissolution of pellets without affecting the bioadhesion.

  15. Impact property enhancement of poly (lactic acid) with different flexible copolymers

    NASA Astrophysics Data System (ADS)

    Likittanaprasong, N.; Seadan, M.; Suttiruengwong, S.

    2015-07-01

    The objective of this work was to improve the impact property of Poly (lactic acid) (PLA) by blending with different copolymers. Six flexible copolymers, namely, acrylonitrile butadiene styrene (ABS) powder, Biomax, polybutyrate adipate co-terephthalate (PBAT), polyether block amide (PEBAX), ethylene-vinyl acetate (EVA) and ethylene acrylic elastomer (EAE), with loading less than 20wt% were used and compared. The rheological, mechanical and morphological properties of samples were investigated by melt flow index, tensile testing, impact testing and scanning electron microscope (SEM), respectively. It was found that PLA added 20wt% EAE showed the highest impact strength (59.5 kJ/m2), which was 22 times higher than neat PLA. The elongation at break was also increased by 12 folds compared to neat PLA. The SEM images showed good interface and distribution for PLA containing 20wt% EAE, 15 phr Biomax and 20 wt% PEBAX.

  16. Extravehicular Activity (EVA) 101: Constellation EVA Systems

    NASA Technical Reports Server (NTRS)

    Jordan, Nicole C.

    2007-01-01

    A viewgraph presentation on Extravehicular Activity (EVA) Systems is shown. The topics include: 1) Why do we need space suits? 2) Protection From the Environment; 3) Primary Life Support System (PLSS); 4) Thermal Control; 5) Communications; 6) Helmet and Extravehicular Visor Assy; 7) Hard Upper Torso (HUT) and Arm Assy; 8) Display and Controls Module (DCM); 9) Gloves; 10) Lower Torso Assembly (LTA); 11) What Size Do You Need?; 12) Boot and Sizing Insert; 13) Boot Heel Clip and Foot Restraint; 14) Advanced and Crew Escape Suit; 15) Nominal & Off-Nominal Landing; 16) Gemini Program (mid-1960s); 17) Apollo EVA on Service Module; 18) A Bold Vision for Space Exploration, Authorized by Congress; 19) EVA System Missions; 20) Configurations; 21) Reduced Gravity Program; and 22) Other Opportunities.

  17. Study on thermal properties and crystallization behavior of electron beam irradiated ethylene vinyl acetate (EVA)/waste tyre dust (WTD) blends in the presence of polyethylene graft maleic anhydride (PEgMAH)

    SciTech Connect

    Ramli, Syuhada; Ahmad, S. H.; Ratnam, C. T.; Athirah, Nurul

    2013-11-27

    The aim of this article is to show the effects of the electron beam irradiation dose and presence of a compatibiliser on the thermal properties and crystallinity of EVA/WTD blends. The purpose of applying electron beam radiation with doses range 50 to 200 kGy and adding a compatibiliser was to enhance the compatibility of the studied blends and at the same time to investigate the possibility of using this technique in the process of recycling polymeric materials. As the compatibilisers, the polyethylene grafted maleic anhydride (PEgMAH) was utilized, they were added at the amounts of 1-5 phr respectively. The enhancement of thermal properties was accompanied by the following effects, discussed in this article: i) an irradiated EVA/WTD blend at 200kGy was found to improve the thermal properties of EVA, ii) the addition of PEgMAH in EVA/WTD blends and the subsequent irradiation allowed prevention of degradation mechanism. iii) the ΔH{sub f} and crystallinity percentage decrease at higher PEgMAH content.

  18. Study on thermal properties and crystallization behavior of electron beam irradiated ethylene vinyl acetate (EVA)/waste tyre dust (WTD) blends in the presence of polyethylene graft maleic anhydride (PEgMAH)

    NASA Astrophysics Data System (ADS)

    Ramli, Syuhada; Ratnam, C. T.; Ahmad, S. H.; Athirah, Nurul

    2013-11-01

    The aim of this article is to show the effects of the electron beam irradiation dose and presence of a compatibiliser on the thermal properties and crystallinity of EVA/WTD blends. The purpose of applying electron beam radiation with doses range 50 to 200 kGy and adding a compatibiliser was to enhance the compatibility of the studied blends and at the same time to investigate the possibility of using this technique in the process of recycling polymeric materials. As the compatibilisers, the polyethylene grafted maleic anhydride (PEgMAH) was utilized, they were added at the amounts of 1-5 phr respectively. The enhancement of thermal properties was accompanied by the following effects, discussed in this article: i) an irradiated EVA/WTD blend at 200kGy was found to improve the thermal properties of EVA, ii) the addition of PEgMAH in EVA/WTD blends and the subsequent irradiation allowed prevention of degradation mechanism. iii) the ΔHf and crystallinity percentage decrease at higher PEgMAH content.

  19. EVA-SCRAM operations

    NASA Technical Reports Server (NTRS)

    Flanigan, Lee A.; Tamir, David; Weeks, Jack L.; Mcclure, Sidney R.; Kimbrough, Andrew G.

    1994-01-01

    This paper wrestles with the on-orbit operational challenges introduced by the proposed Space Construction, Repair, and Maintenance (SCRAM) tool kit for Extra-Vehicular Activity (EVA). SCRAM undertakes a new challenging series of on-orbit tasks in support of the near-term Hubble Space Telescope, Extended Duration Orbiter, Long Duration Orbiter, Space Station Freedom, other orbital platforms, and even the future manned Lunar/Mars missions. These new EVA tasks involve welding, brazing, cutting, coating, heat-treating, and cleaning operations. Anticipated near-term EVA-SCRAM applications include construction of fluid lines and structural members, repair of punctures by orbital debris, refurbishment of surfaces eroded by atomic oxygen, and cleaning of optical, solar panel, and high emissivity radiator surfaces which have been degraded by contaminants. Future EVA-SCRAM applications are also examined, involving mass production tasks automated with robotics and artificial intelligence, for construction of large truss, aerobrake, and reactor shadow shield structures. Realistically achieving EVA-SCRAM is examined by addressing manual, teleoperated, semi-automated, and fully-automated operation modes. The operational challenges posed by EVA-SCRAM tasks are reviewed with respect to capabilities of existing and upcoming EVA systems, such as the Extravehicular Mobility Unit, the Shuttle Remote Manipulating System, the Dexterous End Effector, and the Servicing Aid Tool.

  20. EVA Training and Development Facilities

    NASA Technical Reports Server (NTRS)

    Cupples, Scott

    2016-01-01

    Overview: Vast majority of US EVA (ExtraVehicular Activity) training and EVA hardware development occurs at JSC; EVA training facilities used to develop and refine procedures and improve skills; EVA hardware development facilities test hardware to evaluate performance and certify requirement compliance; Environmental chambers enable testing of hardware from as large as suits to as small as individual components in thermal vacuum conditions.

  1. Barrier properties of PE, PP and EVA (nano)composites - The influence of filler type and concentration

    NASA Astrophysics Data System (ADS)

    Merinska, D.; Kalendova, A.; Tesarikova, A.

    2014-05-01

    Nanocomposite materials with layered clay used as nanofiller and polyethylene (PE), polypropylene (PP) and copolymer ethylene and vinyl acetate matrix (EVA, the content of VA component 19 wt. %) were prepared by compounding the individual components in Brabender kneader. The MMT Na+ and four types of commercial products such as Nanofil N 5 and N3000, Cloisite 93A and 30B were used as nanofillers. Next to the clays microprecipitated CaHCO3, nanosilica and Halloysite tubes were used. The quantity of all the above-mentioned (nano)fillers was 1, 3 and 5 wt. % in relation to the content of montmorillonite. The aim was to evaluate the influence of (nano)filler type and concentration on nanocomposite barrier properties. The morphology of nanocomposite samples was examined by means of XRD analysis illustrated by transmission electronic microscopy TEM. Furthermore, permeability for O2 and CO2 were observed.

  2. Barrier properties of PE, PP and EVA (nano)composites - The influence of filler type and concentration

    SciTech Connect

    Merinska, D.; Kalendova, A.; Tesarikova, A.

    2014-05-15

    Nanocomposite materials with layered clay used as nanofiller and polyethylene (PE), polypropylene (PP) and copolymer ethylene and vinyl acetate matrix (EVA, the content of VA component 19 wt. %) were prepared by compounding the individual components in Brabender kneader. The MMT Na+ and four types of commercial products such as Nanofil N 5 and N3000, Cloisite 93A and 30B were used as nanofillers. Next to the clays microprecipitated CaHCO{sub 3}, nanosilica and Halloysite tubes were used. The quantity of all the above-mentioned (nano)fillers was 1, 3 and 5 wt. % in relation to the content of montmorillonite. The aim was to evaluate the influence of (nano)filler type and concentration on nanocomposite barrier properties. The morphology of nanocomposite samples was examined by means of XRD analysis illustrated by transmission electronic microscopy TEM. Furthermore, permeability for O{sub 2} and CO{sub 2} were observed.

  3. EVA Retriever Demonstration

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The EVA retriever is demonstrated in the Manipulator Development Facility (MDF). The retriever moves on the air bearing table 'searching' for its target, in this case tools 'dropped' by astronauts on orbit.

  4. Effect of poly(vinyl alcohol-co-vinyl acetate) copolymer blockiness on the dynamic interfacial tension and dilational viscoelasticity of polymer-anionic surfactant complex at the water-1-chlorobutane interface.

    PubMed

    Atanase, Leonard Ionut; Bistac, Sophie; Riess, Gérard

    2015-04-07

    Poly(vinyl alcohol-co-vinyl acetate) (PVA) copolymers obtained by partial hydrolysis of poly(vinyl acetate) (PVAc) are of practical importance for many applications, including emulsion and suspension polymerization processes. Their molecular characteristics have a major influence on the colloidal and interfacial properties. The most significant characteristics are represented by the average degree of hydrolysis D̅H̅, average degree of polymerization D̅P̅w̅ but also by the average acetate sequence length n(VAc)(0) which designates the so-called blockiness. Colloidal aggregates were observed in the aqueous PVA solutions having a D̅H̅ value of 73 mol%. The volume fraction of these aggregates at a given D̅H̅ value is directly correlated to the blockiness. Three PVA samples with identical D̅H̅ and D̅P̅w̅ but different blockiness were examined. By pendant drop and oscillating pendant drop techniques it was shown that the PVA sample having the lowest blockiness and thus the lowest volume fraction of colloidal aggregates has lower interfacial tension and elastic modulus E' values. On the contrary, the corresponding values are highest for PVA sample of higher blockiness. In the presence of sodium dodecyl sulfate (SDS), the colloidal aggregates are disaggregated by complex formation due to the hydrophobic-hydrophobic interactions. The PVA-SDS complex acts as a partial polyelectrolyte that induces the stretching of the chains and thus a reduction of the interface thickness. In this case, the interfacial tension and the elastic modulus both increase with increasing SDS concentration for all three PVA samples and the most significant effect was noticed for the most "blocky" copolymer sample.

  5. EVA Glove Research Team

    NASA Technical Reports Server (NTRS)

    Strauss, Alvin M.; Peterson, Steven W.; Main, John A.; Dickenson, Rueben D.; Shields, Bobby L.; Lorenz, Christine H.

    1992-01-01

    The goal of the basic research portion of the extravehicular activity (EVA) glove research program is to gain a greater understanding of the kinematics of the hand, the characteristics of the pressurized EVA glove, and the interaction of the two. Examination of the literature showed that there existed no acceptable, non-invasive method of obtaining accurate biomechanical data on the hand. For this reason a project was initiated to develop magnetic resonance imaging as a tool for biomechanical data acquisition and visualization. Literature reviews also revealed a lack of practical modeling methods for fabric structures, so a basic science research program was also initiated in this area.

  6. EVA Skills Training

    NASA Technical Reports Server (NTRS)

    Parazynski, Scott

    2012-01-01

    Dr. Parazynski and a colleague from Extravehicular Activity (EVA), Robotics, & Crew Systems Operations (DX) worked closely to build the EVA Skills Training Program, and for the first time, defined the gold standards of EVA performance, allowing crewmembers to increase their performance significantly. As part of the program, individuals had the opportunity to learn at their own rate, taking additional water time as required, to achieve that level of performance. This focus on training to one's strengths and weaknesses to bolster them enabled the Crew Office and DX to field a much larger group of spacewalkers for the daunting "wall of EVA" required for the building and maintenance of the ISS. Parazynski also stressed the need for designers to understand the capabilities and the limitations of a human in a spacesuit, as well as opportunities to improve future generations of space. He shared lessons learned (how the Crew Office engaged in these endeavors) and illustrated the need to work as a team to develop these complex systems.

  7. Real-Time EVA Troubleshooting

    NASA Technical Reports Server (NTRS)

    Leestma, David

    2013-01-01

    David Leestma was EV-1 for the STS-41G extravehicular activity (EVA) with Kathy Sullivan (first American female spacewalker). They conducted an EVA to fully demonstrate the feasibility of refueling satellites from the Space Shuttle, and performed the first contingency EVA task involving the Ku-band antenna. STS-41G was the fourth Space Shuttle mission to perform an EVA, and Leestma related his experiences with training, the spacesuit, and EVA tasks that were conducted on October 11, 1984 during this mission.

  8. Comb-like amphiphilic copolymers bearing acetal-functionalized backbones with the ability of acid-triggered hydrophobic-to-hydrophilic transition as effective nanocarriers for intracellular release of curcumin.

    PubMed

    Zhao, Junqiang; Wang, Haiyang; Liu, Jinjian; Deng, Liandong; Liu, Jianfeng; Dong, Anjie; Zhang, Jianhua

    2013-11-11

    The pH-responsive micelles have enormous potential as nanosized drug carriers for cancer therapy due to their physicochemical changes in response to the tumor intracellular acidic microenvironment. Herein, a series of comb-like amphiphilic copolymers bearing acetal-functionalized backbone were developed based on poly[(2,4,6-trimethoxybenzylidene-1,1,1-tris(hydroxymethyl) ethane methacrylate-co-poly(ethylene glycol) methyl ether methacrylate] [P(TTMA-co-mPEGMA)] as effective nanocarriers for intracellular curcumin (CUR) release. P(TTMA-co-mPEGMA) copolymers with different hydrophobic-hydrophilic ratios were prepared by one-step reversible addition fragmentation chain transfer (RAFT) copolymerization of TTMA and mPEGMA. Their molecular structures and chemical compositions were confirmed by (1)H NMR, Fourier transform infrared spectroscopy (FT-IR) and gel permeation chromatography (GPC). P(TTMA-co-mPEGMA) copolymers could self-assemble into nanosized micelles in aqueous solution and displayed low critical micelle concentration (CMC). All P(TTMA-co-mPEGMA) micelles displayed excellent drug loading capacity, due to the strong π-π conjugate action and hydrophobic interaction between the PTTMA and CUR. Moreover, the hydrophobic PTTMA chain could be selectively hydrolyzed into a hydrophilic backbone in the mildly acidic environment, leading to significant swelling and final disassembly of the micelles. These morphological changes of P(TTMA-co-mPEGMA) micelles with time at pH 5.0 were determined by DLS and TEM. The in vitro CUR release from the micelles exhibited a pH-dependent behavior. The release rate of CUR was significantly accelerated at mildly acidic pH of 4.0 and 5.0 compared to that at pH 7.4. Toxicity test revealed that the P(TTMA-co-mPEGMA) copolymers exhibited low cytotoxicity, whereas the CUR-loaded micelles maintained high cytotoxicity for HepG-2 and EC-109 cells. The results indicated that the novel P(TTMA-co-mPEGMA) micelles with low CMC, small and tunable

  9. Development of an EVA systems cost model. Volume 3: EVA systems cost model

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The EVA systems cost model presented is based on proposed EVA equipment for the space shuttle program. General information on EVA crewman requirements in a weightless environment and an EVA capabilities overview are provided.

  10. Extravehicular Activity (EVA) Hardware & Operations Overview

    NASA Technical Reports Server (NTRS)

    Moore, Sandra; Marmolejo, Jose

    2014-01-01

    The objectives of this presentation are to: Define Extravehicular Activity (EVA), identify the reasons for conducting an EVA, and review the role that EVA has played in the space program; Identify the types of EVAs that may be performed; Describe some of the U.S. Space Station equipment and tools that are used during an EVA, such as the Extravehicular Mobility Unit (EMU), the Simplified Aid For EVA Rescue (SAFER), the International Space Station (ISS) Joint Airlock and Russian Docking Compartment 1 (DC-1), and EVA Tools & Equipment; Outline the methods and procedures of EVA Preparation, EVA, and Post-EVA operations; Describe the Russian spacesuit used to perform an EVA; Provide a comparison between U.S. and Russian spacesuit hardware and EVA support; and Define the roles that different training facilities play in EVA training.

  11. What's NEXT for EVA

    NASA Astrophysics Data System (ADS)

    Fullerton, R. K.

    The NASA Exploration Team (NEXT) promotes a vision of new capabilities through an ongoing, integrated and prioritized investment in leap ahead concepts and technologies. The wise marriage of robotic and human work systems is a key element of this vision. To enable a wide array of future destinations and applications, it is important to develop and implement systems which are scalable, environmentally adaptable, reliable and efficiently productive. This paper highlights a few of the recently envisioned customers and applications for advanced extravehicular activity (EVA) systems. It also summarizes recent conceptual and practical studies to define the features and options of such a system. More importantly, it communicates the need and progress of knowledge capture, clearly defined performance targets, credible decision making tools, tangible benefits and creative leverage. With this integrated long range approach, space exploration and EVA can accelerate and enable the future for all generations.

  12. Space Shuttle/Orbiter EVA and EVA provisions

    NASA Technical Reports Server (NTRS)

    Goodman, J. R.

    1980-01-01

    EVA objectives, procedures, and equipment for the Shuttle are reviewed. The EVA will occur as a planned excursion, to complete a mission objective, or on a contingency basis as support for the mission or to effect repairs to the Orbiter or its payload. Configurations for the placement of the airlock for EVA with and without Spacelab payloads are discussed, along with the various EVA tasks which could be expected as necessary for mission completion. Handholds have been placed in strategic positions on the RMS and along the payload doors, and a safety tether has been incorporated with line extension out to 25 ft. Off-the-shelf tools such as needlenose pliers, forceps, diagonal cutters, etc. are carried as standard equipment for the repair of malfunctioning equipment and doorlatches. Finally, attention is given to EVA lighting, communication, life-support, and work station restraint systems.

  13. EVA Performance Prediction

    NASA Technical Reports Server (NTRS)

    Peacock, Brian; Maida, James; Rajulu, Sudhakar

    2004-01-01

    Astronaut physical performance capabilities in micro gravity EV A or on planetary surfaces when encumbered by a life support suit and debilitated by a long exposure to micro gravity will be less than unencumbered pre flight capabilities. The big question addressed by human factors engineers is: what can the astronaut be expected to do on EVA or when we arrive at a planetary surface? A second question is: what aids to performance will be needed to enhance the human physical capability? These questions are important for a number of reasons. First it is necessary to carry out accurate planning of human physical demands to ensure that time and energy critical tasks can be carried out with confidence. Second it is important that the crew members (and their ground or planetary base monitors) have a realistic picture of their own capabilities, as excessive fatigue can lead to catastrophic failure. Third it is important to design appropriate equipment to enhance human sensory capabilities, locomotion, materials handling and manipulation. The evidence from physiological research points to musculoskeletal, cardiovascular and neurovestibular degradation during long duration exposure to micro gravity . The evidence from the biomechanics laboratory (and the Neutral Buoyancy Laboratory) points to a reduction in range of motion, strength and stamina when encumbered by a pressurized suit. The evidence from a long history of EVAs is that crewmembers are indeed restricted in their physical capabilities. There is a wealth of evidence in the literature on the causes and effects of degraded human performance in the laboratory, in sports and athletics, in industry and in other physically demanding jobs. One approach to this challenge is through biomechanical and performance modeling. Such models must be based on thorough task analysis, reliable human performance data from controlled studies, and functional extrapolations validated in analog contexts. The task analyses currently carried

  14. Differences in the thickness of mouthguards fabricated from ethylene vinyl acetate copolymer sheets with differently arranged v-shaped grooves: part 2 - effect of shape on the working model.

    PubMed

    Takahashi, Mutsumi; Koide, Kaoru; Mizuhashi, Fumi

    2014-12-01

    The aim of this study was to evaluate the change in thickness of a working model mouthguard sheet due to different shape. Mouthguards were fabricated with ethylene vinyl acetate (EVA) sheets (4.0 mm thick) using a vacuum-forming machine. Two shapes of the sheet were compared: normal sheet or v-shaped groove 10-40 mm from the anterior end. Additionally, two shapes of the working model were compared; the basal plane was vertical to the tooth axis of the maxillary central incisor (condition A), and the occlusal plane was parallel to the basal plane (condition B). Sheets were heated until they sagged 15 mm below the clamp. Postmolding thickness was determined for the incisal portion (incisal edge and labial surface) and molar portion (cusp and buccal surface). Differences in the change in thickness due to the shape of the sheets and model were analyzed using two-way anova followed by a Bonferroni's multiple comparison tests. The thickness of the mouthguard sheet with v-shaped grooves was more than that of the normal sheet at all measuring points under condition A and condition B (P < 0.01). The thickness of condition B was less than that of condition A, there the incisal portion in the normal sheet and the incisal edge in the sheet with v-shaped grooves (P < 0.01). The present results suggested that thickness after molding was secured by the use of the sheet with v-shaped grooves. In particular, the model with the undercut on the labial surface may be clinically useful.

  15. Thermal processing of EVA encapsulants and effects of formulation additives

    SciTech Connect

    Pern, F.J.; Glick, S.H.

    1996-05-01

    The authors investigated the in-situ processing temperatures and effects of various formulation additives on the formation of ultraviolet (UV) excitable chromophores, in the thermal lamination and curing of ethylene-vinyl acetate (EVA) encapsulants. A programmable, microprocessor-controlled, double-bag vacuum laminator was used to study two commercial as formulated EVA films, A9918P and 15295P, and solution-cast films of Elvaxrm (EVX) impregnated with various curing agents and antioxidants. The results show that the actual measured temperatures of EVA lagged significantly behind the programmed profiles for the heating elements and were affected by the total thermal mass loaded inside the laminator chamber. The antioxidant Naugard P{trademark}, used in the two commercial EVA formulations, greatly enhances the formation of UV-excitable, short chromophores upon curing, whereas other tested antioxidants show little effect. A new curing agent chosen specifically for the EVA formulation modification produces little or no effect on chromophore formation, no bubbling problems in the glass/EVX/glass laminates, and a gel content of {approximately}80% when cured at programmed 155{degrees}C for 4 min. Also demonstrated is the greater discoloring effect with higher concentrations of curing-generated chromophores.

  16. ESEM analysis of polymeric film in EVA-modified cement paste

    SciTech Connect

    Silva, D.A. . E-mail: denise@ecv.ufsc.br; Monteiro, P.J.M.

    2005-10-01

    Portland cement pastes modified by 20% weight (polymer/cement ratio) of poly(ethylene-co-vinyl acetate) (EVA) were prepared, cured, and immersed in water for 11 days. The effects of water saturation and drying on the EVA polymeric film formed in cement pastes were observed using environmental scanning electron microscopy (ESEM). This technique allowed the imaging of the EVA film even in saturated samples. The decrease of the relative humidity inside the ESEM chamber did not cause any visual modification of the polymeric film during its drying.

  17. EVA safety: Space suit system interoperability

    NASA Technical Reports Server (NTRS)

    Skoog, A. I.; McBarron, J. W.; Abramov, L. P.; Zvezda, A. O.

    1995-01-01

    The results and the recommendations of the International Academy of Astronautics extravehicular activities (IAA EVA) Committee work are presented. The IAA EVA protocols and operation were analyzed for harmonization procedures and for the standardization of safety critical and operationally important interfaces. The key role of EVA and how to improve the situation based on the identified EVA space suit system interoperability deficiencies were considered.

  18. ChEVAS: Combining Suprarenal EVAS with Chimney Technique

    SciTech Connect

    Torella, Francesco; Chan, Tze Y. Shaikh, Usman; England, Andrew; Fisher, Robert K.; McWilliams, Richard G.

    2015-10-15

    Endovascular sealing with the Nellix{sup ®} endoprosthesis (EVAS) is a new technique to treat infrarenal abdominal aortic aneurysms. We describe the use of endovascular sealing in conjunction with chimney stents for the renal arteries (chEVAS) in two patients, one with a refractory type Ia endoleak and an expanding aneurysm, and one with a large juxtarenal aneurysm unsuitable for fenestrated endovascular repair (EVAR). Both aneurysms were successfully excluded. Our report confirms the utility of chEVAS in challenging cases, where suprarenal seal is necessary. We suggest that, due to lack of knowledge on its durability, chEVAS should only been considered when more conventional treatment modalities (open repair and fenestrated EVAR) are deemed difficult or unfeasible.

  19. Spectroscopic, scanning laser OBIC, and I-V/QE characterizations of browned EVA solar cells

    SciTech Connect

    Pern, F.J.; Eisgruber, I.L.; Micheels, R.H.

    1996-05-01

    The effects of ethylene-vinyl acetate (EVA) discoloration due to accelerated field or laboratory exposure on the encapsulated silicon (Si) solar cells or EVA/glass laminates were characterized quantitatively by using non-invasive, non-destructive ultraviolet-visible (UV-vis) spectrophotometry, spectrocolorimetry, spectrofluorometry, scanning laser OBIC (optical beam induced current) spectroscopy, and current-voltage (I-V) and quantum efficiency (QE) measurements. The results show that the yellowness index (YI) measured directly over the AR-coated solar cells under the glass superstrate increased from the range of -80 to -90 to the range of -20 to 15 as the EVA changed from clear to brown. The ratio of two fluorescence emission peak areas generally increased from 1.45 to 5.69 as browning increased, but dropped to 4.21 on a darker EVA. For a solar cell with brown EVA in the central region, small-area grating QE measurements and scanning laser OBIC analysis between the brown and clear EVA regions showed that the quantum efficiency loss at 633 nm was 42%-48% of the loss at 488 nm, due to a reduced decrease of transmittance in browned EVA at the longer wavelengths. The portion of the solar cell under the browned EVA showed a decrease of {approximately}36% in efficiency, as compared to the cell efficiency under clear EVA. Transmittance loss at 633 nm was 38% of the loss at 488 nm for a light yellow-brown EVA/glass laminate that showed a small increase of 10 in the yellowness index.

  20. EVA worksite analysis--use of computer analysis for EVA operations development and execution.

    PubMed

    Anderson, D

    1999-01-01

    To sustain the rate of extravehicular activity (EVA) required to assemble and maintain the International Space Station, we must enhance our ability to plan, train for, and execute EVAs. An underlying analysis capability has been developed to ensure EVA access to all external worksites as a starting point for ground training, to generate information needed for on-orbit training, and to react quickly to develop contingency EVA plans, techniques, and procedures. This paper describes the use of computer-based EVA worksite analysis techniques for EVA worksite design. EVA worksite analysis has been used to design 80% of EVA worksites on the U.S. portion of the International Space Station. With the launch of the first U.S. element of the station, EVA worksite analysis is being developed further to support real-time analysis of unplanned EVA operations. This paper describes this development and deployment of EVA worksite analysis for International Space Station (ISS) mission support.

  1. Post-Shuttle EVA Operations on ISS

    NASA Technical Reports Server (NTRS)

    West, Bill; Witt, Vincent; Chullen, Cinda

    2010-01-01

    The EVA hardware used to assemble and maintain the ISS was designed with the assumption that it would be returned to Earth on the Space Shuttle for ground processing, refurbishment, or failure investigation (if necessary). With the retirement of the Space Shuttle, a new concept of operations was developed to enable EVA hardware (EMU, Airlock Systems, EVA tools, and associated support equipment and consumables) to perform ISS EVAs until 2016 and possibly beyond to 2020. Shortly after the decision to retire the Space Shuttle was announced, NASA and the One EVA contractor team jointly initiated the EVA 2010 Project. Challenges were addressed to extend the operating life and certification of EVA hardware, secure the capability to launch EVA hardware safely on alternate launch vehicles, and protect EMU hardware operability on orbit for long durations.

  2. Application of shuttle EVA systems to payloads. Volume 1: EVA systems and operational modes description

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Descriptions of the EVA system baselined for the space shuttle program were provided, as well as a compendium of data on available EVA operational modes for payload and orbiter servicing. Operational concepts and techniques to accomplish representative EVA payload tasks are proposed. Some of the subjects discussed include: extravehicular mobility unit, remote manipulator system, airlock, EVA translation aids, restraints, workstations, tools and support equipment.

  3. Application of Shuttle EVA Systems to Payloads. Volume 2: Payload EVA Task Completion Plans

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Candidate payload tasks for EVA application were identified and selected, based on an analysis of four representative space shuttle payloads, and typical EVA scenarios with supporting crew timelines and procedures were developed. The EVA preparations and post EVA operations, as well as the timelines emphasizing concurrent payload support functions, were also summarized.

  4. Miniature EVA Software Defined Radio

    NASA Technical Reports Server (NTRS)

    Pozhidaev, Aleksey

    2012-01-01

    As NASA embarks upon developing the Next-Generation Extra Vehicular Activity (EVA) Radio for deep space exploration, the demands on EVA battery life will substantially increase. The number of modes and frequency bands required will continue to grow in order to enable efficient and complex multi-mode operations including communications, navigation, and tracking applications. Whether conducting astronaut excursions, communicating to soldiers, or first responders responding to emergency hazards, NASA has developed an innovative, affordable, miniaturized, power-efficient software defined radio that offers unprecedented power-efficient flexibility. This lightweight, programmable, S-band, multi-service, frequency- agile EVA software defined radio (SDR) supports data, telemetry, voice, and both standard and high-definition video. Features include a modular design, an easily scalable architecture, and the EVA SDR allows for both stationary and mobile battery powered handheld operations. Currently, the radio is equipped with an S-band RF section. However, its scalable architecture can accommodate multiple RF sections simultaneously to cover multiple frequency bands. The EVA SDR also supports multiple network protocols. It currently implements a Hybrid Mesh Network based on the 802.11s open standard protocol. The radio targets RF channel data rates up to 20 Mbps and can be equipped with a real-time operating system (RTOS) that can be switched off for power-aware applications. The EVA SDR's modular design permits implementation of the same hardware at all Network Nodes concept. This approach assures the portability of the same software into any radio in the system. It also brings several benefits to the entire system including reducing system maintenance, system complexity, and development cost.

  5. Study on structure and hydrophobicity of PP/EVA co-blending membrane: Quenching rate

    NASA Astrophysics Data System (ADS)

    Tang, Na; Li, Zhao; Hua, Xinxin

    2017-03-01

    Isotactic polypropylene (iPP)/ethylene vinyl acetate (EVA) co-blending hydrophobic microporous membranes for vacuum membrane distillation (VMD) were prepared via thermally induced phase separation (TIPS). In the process of preparation, quenching rate has a great influence on the membrane morphology.

  6. Advanced EVA system design requirements study

    NASA Technical Reports Server (NTRS)

    1986-01-01

    Design requirements and criteria for the Space Station Advanced Extravehicular Activity System (EVAS) including crew enclosures, portable life support systems, maneuvering propulsion systems, and related extravehicular activity (EVA) support equipment were defined and established. The EVA mission requirements, environments, and medical and physiological requirements, as well as opertional, procedures, and training issues were considered.

  7. European EVA decompression sickness risks

    NASA Astrophysics Data System (ADS)

    Vogt, Lorenz; Wenzel, Jürgen; Skoog, A. I.; Luck, S.; Svensson, Bengt

    For the first manned flight of Hermes there will be a capability of performing EVA. The European EVA Space Suit will be an anthropomorphic system with an internal pressure of 500 hPa of pure oxygen. The pressure reduction from the Hermes cabin pressure of 1013 hPa will induce a risk for Decompression Sickness (DCS) for the EVA crewmember if no adequate protective procedures are implemented. Specific decompression procedures have to be developed. From a critical review of the literature and by using knowledge gained from research conducted in the past in the fields of diving and aerospace medicine safe protective procedures are proposed for the European EVA scenario. An R factor of 1.2 and a tissue half-time ( t1/2) of 360 minutes in a single-tissue model have been identified as appropriate operational values. On the basis of an acceptable risk level of approximately 1%, oxygen prebreathing times are proposed for (a) direct pressure reduction from 1013 hPa to a suit pressure of 500 hPa, and (b) staged decompression using a 700 hPa intermediate stage in the spacecraft cabin. In addition, factors which influence individual susceptibility to DCS are identified. Recommendations are also given in the areas of crew selection and medical monitoring requirements together with therapeutic measures that can be implemented in the Hermes scenario. A method for demonstration of the validity of proposed risks and procedures is proposed.

  8. Block copolymer nanolithography for the fabrication of patterned media.

    SciTech Connect

    Warke, Vishal V; Bakker, Martin G; Hong, Kunlun; Mays, Jimmy; Britt, Phillip F; Li, Xuefa; Wang, Jin

    2008-01-01

    Abstract Bit patterned perpendicular media has the potential to increase the density of magnetic recording beyond what can be achieved by granular media. Self assembling diblock copolymers are of interest as templates for patterned media, as they potentially provide a low cost fabrication route. A method to fabricate the desired pattern using cylinder forming diblock copolymers of (PS-b-PMMA) as template is reported. Upon phase separation hexagonally packed cylinders of the minority phase (PMMA) surrounded by the continuous majority phase (PS) are obtained. The processing sequence began with spin coating the block copolymer on a suitable substrate, followed by annealing the block copolymer thin film in vacuum to orient it perpendicular to the substrate. Block copolymer templates were obtained by glacial acetic acid treatment which opened the pores in the block copolymer thin film. Ni was electrodeposited in the block copolymer templates and this pattern was then transferred onto the underlying substrate by ion milling

  9. A type of esophageal stent coating composed of one 5-fluorouracil-containing EVA layer and one drug-free protective layer: in vitro release, permeation and mechanical properties.

    PubMed

    Guo, Qinghai; Guo, Shengrong; Wang, Zhongmin

    2007-04-23

    A type of esophageal stent coating was investigated, which consists of one 5-fluorouracil (5-FU)-containing ethylene-vinyl acetate (EVA) copolymer layer and one drug-free EVA protective layer. The amount of 5-FU permeated through the protective layer (100 mum) is thousands of times lower than that of 5-FU released from the drug-loaded layer, indicating that the coating releases drug molecules in a unidirectional fashion. The barrier of the protective layer can be attributed to a tiny flux of 5-FU through the EVA film. In vitro release profiles of the stent coatings with various drug contents were investigated in pH 6.5 phosphate buffer solution. The results show that, the burst effect is not obvious for the coatings with 20-50% of 5-FU and the release profiles can be characterized by a first faster release rate phase followed by a decrease in release rate. The release data in the early and late stages can all be well fitted with zero-order kinetics, and the possible reasons for the release profiles were discussed. The rate of 5-FU permeation through porcine esophageal mucosa from the coatings can be adjusted by changing drug content of the coatings. The increase of drug content of the coatings significantly leads to the decrease of the maximum elongation, maximum tensible strength and maximum tear strength, and the increase of the modulus of elasticity. The coatings with 20-60% of drug attached to a stent can endure repeated binding and liberation via a stent introducer.

  10. Post-Shuttle EVA Operations on ISS

    NASA Technical Reports Server (NTRS)

    West, William; Witt, Vincent; Chullen, Cinda

    2010-01-01

    The expected retirement of the NASA Space Transportation System (also known as the Space Shuttle ) by 2011 will pose a significant challenge to Extra-Vehicular Activities (EVA) on-board the International Space Station (ISS). The EVA hardware currently used to assemble and maintain the ISS was designed assuming that it would be returned to Earth on the Space Shuttle for refurbishment, or if necessary for failure investigation. With the retirement of the Space Shuttle, a new concept of operations was developed to enable EVA hardware (Extra-vehicular Mobility Unit (EMU), Airlock Systems, EVA tools, and associated support hardware and consumables) to perform ISS EVAs until 2015, and possibly beyond to 2020. Shortly after the decision to retire the Space Shuttle was announced, the EVA 2010 Project was jointly initiated by NASA and the One EVA contractor team. The challenges addressed were to extend the operating life and certification of EVA hardware, to secure the capability to launch EVA hardware safely on alternate launch vehicles, to protect for EMU hardware operability on-orbit, and to determine the source of high water purity to support recharge of PLSSs (no longer available via Shuttle). EVA 2010 Project includes the following tasks: the development of a launch fixture that would allow the EMU Portable Life Support System (PLSS) to be launched on-board alternate vehicles; extension of the EMU hardware maintenance interval from 3 years (current certification) to a minimum of 6 years (to extend to 2015); testing of recycled ISS Water Processor Assembly (WPA) water for use in the EMU cooling system in lieu of water resupplied by International Partner (IP) vehicles; development of techniques to remove & replace critical components in the PLSS on-orbit (not routine); extension of on-orbit certification of EVA tools; and development of an EVA hardware logistical plan to support the ISS without the Space Shuttle. Assumptions for the EVA 2010 Project included no more

  11. Flecainide acetate acetic acid solvates.

    PubMed

    Veldre, Kaspars; Actiņs, Andris; Eglite, Zane

    2011-02-01

    Flecainide acetate forms acetic acid solvates with 0.5 and 2 acetic acid molecules. Powder X-ray diffraction, differential thermal analysis/thermogravimetric, infrared, and potentiometric titration were used to determine the composition of solvates. Flecainide acetate hemisolvate with acetic acid decomposes to form a new crystalline form of flecainide acetate. This form is less stable than the already known polymorphic form at all temperatures, and it is formed due to kinetic reasons. Both flecainide acetate nonsolvated and flecainide acetate hemisolvate forms crystallize in monoclinic crystals, but flecainide triacetate forms triclinic crystals. Solvate formation was not observed when flecainide base was treated with formic acid, propanoic acid, and butanoic acid. Only nonsolvated flecainide salts were obtained in these experiments.

  12. EVA Radio DRATS 2011 Report

    NASA Technical Reports Server (NTRS)

    Swank, Aaron J.; Bakula, Casey J.

    2012-01-01

    In the Fall of 2011, National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) participated in the Desert Research and Technology Studies (DRATS) field experiments held near Flagstaff, Arizona. The objective of the DRATS outing is to provide analog mission testing of candidate technologies for space exploration, especially those technologies applicable to human exploration of extra- terrestrial rocky bodies. These activities are performed at locations with similarities to extra-terrestrial conditions. This report describes the Extravehicular Activity (EVA) Dual-Band Radio Communication System which was demonstrated during the 2011 outing. The EVA radio system is designed to transport both voice and telemetry data through a mobile ad hoc wireless network and employs a dual-band radio configuration. Some key characteristics of this system include: 1. Dual-band radio configuration. 2. Intelligent switching between two different capability wireless networks. 3. Self-healing network. 4. Simultaneous data and voice communication.

  13. Interfacing with an EVA Suit

    NASA Technical Reports Server (NTRS)

    Ross, Amy

    2011-01-01

    A NASA spacesuit under the EVA Technology Domain consists of a suit system; a PLSS; and a Power, Avionics, and Software (PAS) system. Ross described the basic functions, components, and interfaces of the PLSS, which consists of oxygen, ventilation, and thermal control subsystems; electronics; and interfaces. Design challenges were reviewed from a packaging perspective. Ross also discussed the development of the PLSS over the last two decades.

  14. Ethylene vinyl acetate as matrix for oral sustained release dosage forms produced via hot-melt extrusion.

    PubMed

    Almeida, A; Possemiers, S; Boone, M N; De Beer, T; Quinten, T; Van Hoorebeke, L; Remon, J P; Vervaet, C

    2011-02-01

    Different ethylene vinyl acetate grades (EVA9, EVA15, EVA28 and EVA40 having a VA content of 9%, 15%, 28% and 40%, respectively) were characterized via differential scanning calorimetry. Glass transition temperature (T(g)), polymer crystallinity, melting point and polymer flexibility were positively influenced by the vinyl acetate content. The processability of EVA-based formulations produced by means of hot-melt extrusion (2mm die) was evaluated in function of VA content, extrusion temperature (60-140°C) and metoprolol tartrate (MPT, used as model drug) concentration (10-60%). Matrices containing 50% MPT resulted in smooth-surfaced extrudates, whereas at 60% drug content severe surface defects (shark skinning) were observed. Drug release from EVA/MPT matrices (50/50, w/w) was affected by the EVA grades: 90% after 24h for EVA15 and 28, while EVA9 and EVA40 formulations released 80% and 60%, respectively. Drug release also depended on drug loading and extrusion temperature. For all systems, the total matrix porosity (measured by X-ray tomography) was decreased after dissolution due to elastic rearrangement of the polymer. However, the largest porosity reduction was observed for EVA40 matrices as partial melting of the structure (melt onset temperature: 34.7°C) also contributed (thereby reducing the drug release pathway and yielding the lowest release rate from EVA40 formulations). The Simulator of the Human Intestinal Microbial Ecosystem (SHIME) used to evaluate the stability of EVA during gastrointestinal transit showed that EVA was not modified during GI transit, nor did it affect the GI ecosystem following oral administration.

  15. Climbing the Extravehicular Activity (EVA) Wall - Safely

    NASA Technical Reports Server (NTRS)

    Fuentes, Jose; Greene, Stacie

    2010-01-01

    The success of the EVA team, that includes the EVA project office, Crew Office, Mission Operations, Engineering and Safety, is assured by the full integration of all necessary disciplines. Safety participation in all activities from hardware development concepts, certification and crew training, provides for a strong partnership within the team. Early involvement of Safety on the EVA team has mitigated risk and produced a high degree of mission success.

  16. STS-64 Mission Photograph - Extravehicular Activity (EVA)

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Astronaut Mark Lee floats freely as he tests the new backpack called the Simplified Aid for EVA Rescue (SAFER) system. SAFER is designed for use in the event a crew member becomes untethered while conducting an EVA. The STS-64 mission marked the first untethered U.S. EVA in 10 years, and was launched on September 9, 1994, aboard the Space Shuttle Orbiter Discovery.

  17. Improved crystallinity and dynamic mechanical properties of reclaimed waste tire rubber/EVA blends under the influence of electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Ramarad, Suganti; Ratnam, Chantara T.; Khalid, Mohammad; Chuah, Abdullah Luqman; Hanson, Svenja

    2017-01-01

    Dependence on automobiles has led to a huge amount of waste tires produced annually around the globe. In this study, the feasibility of recycling these waste tires by blending reclaimed waste tire rubber (RTR) with poly(ethylene-co-vinyl acetate) (EVA) and electron beam irradiation was studied. The RTR/EVA blends containing 100-0 wt% of RTR were prepared in the internal mixer followed by electron beam (EB) irradiation with doses ranging from 50 to 200 kGy. The processing torques, calorimetric and dynamic mechanical properties of the blends were studied. Blends were found to have lower processing torque indicating easier processability of RTR/EVA blends compared to EVA. RTR domains were found to be dispersed in EVA matrix, whereas, irradiation improved the dispersion of RTR into smaller domains in EVA matrix. Results showed the addition of EVA improves the efficiency of irradiation induced crosslink formation and dynamic mechanical properties of the blends at the expense of the calorimetric properties. Storage and loss modulus of 50 wt% RTR blend was higher than RTR and EVA, suggesting partial miscibility of the blend. Whereas, electron beam irradiation improved the calorimetric properties and dynamic mechanical properties of the blends through redistribution of RTR in smaller domain sizes within EVA.

  18. EVA Systems Flight Controller Talks With Students

    NASA Video Gallery

    From NASA's International Space Station Mission Control Center, EVA Systems Flight Controller Sandy Fletcher participates in a Digital Learning Network (DLN) event with students from Northtowne Ele...

  19. Influence of association of "EVA-NBR" on indirect tensile strength of modified bituminous concrete

    NASA Astrophysics Data System (ADS)

    Chinoun, M.; Soudani, K.; Haddadi, S.

    2016-04-01

    The aim of this work is to contribute to the improvement of the mechanical properties of bituminous concrete by modification of bituminous concrete. In this study, we present the results of the indirect tensile strength "ITS" of modified bituminous concrete by the combination of two modifiers, one is a plastomer EVA (Ethylene Vinyl Acetate) and the other is a industrial waste from the shoe soles grinding NBR (Nitrile Butadiene Rubber) as crumb rubber. To modify the bitumen a wet process was used. The results show that the modification of bitumen by EVA-NBR combination increases their resistance to the indirect traction "ITS" compared to the bituminous concrete control. The mixture of 5% [50% EVA+ 50% NBR] is given the best result among the other associations.

  20. Mesoxalaldehyde acetals

    SciTech Connect

    Gordeeva, G.N.; Kalashnikov, S.M.; Popov, Yu.N.; Kruglov, E.A.; Imashev, U.B.

    1987-11-10

    The treatment of methylglyoxal acetals by alkyl nitrites in the presence of the corresponding aliphatic alcohols and hydrochloric acid leads to the formation of linear mesoxalaldehyde acetals, whose structure was established by NMR spectroscopy and mass spectrometry. The major pathways for the decomposition of these molecules upon electron impact were established.

  1. Emergency vehicle alert system (EVAS)

    NASA Technical Reports Server (NTRS)

    Reed, Bill; Crump, Roger; Harper, Warren; Myneni, Krishna

    1995-01-01

    The Emergency Vehicle Alert System (EVAS) program is sponsored by the NASA/MSFC Technology Utilization (TU) office. The program was conceived to support the needs of hearing impaired drivers. The objective of the program is to develop a low-cost, small device which can be located in a personal vehicle and warn the driver, via a visual means, of the approach of an emergency vehicle. Many different technologies might be developed for this purpose and each has its own advantages and drawbacks. The requirements for an acoustic detection system, appear to be pretty stringent and may not allow the development of a reliable, low-cost device in the near future. The problems include variations in the sirens between various types of emergency vehicles, distortions due to wind and surrounding objects, competing background noise, sophisticated signal processing requirements, and omni-directional coverage requirements. Another approach is to use a Radio Frequency (RF) signal between the Emergency Vehicle (EV) and the Personal Vehicle (PV). This approach requires a transmitter on each EV and a receiver in each PV, however it is virtually assured that a system can be developed which works. With this approach, the real technology issue is how to make a system work as inexpensively as possible. This report gives a brief summary of the EVAS program from its inception and concentrates on describing the activities that occurred during Phase 4. References 1-3 describe activities under Phases 1-3. In the fourth phase of the program, the major effort to be expended was in development of the microcontroller system for the PV, refinement of some system elements and packaging for demonstration purposes. An EVAS system was developed and demonstrated which used standard spread spectrum modems with minor modifications.

  2. Exploration EVA Purge Flow Assessment

    NASA Technical Reports Server (NTRS)

    Navarro, Moses; Conger, Bruce; Campbell, Colin

    2011-01-01

    An advanced future spacesuit will require properly sized suit and helmet purge flow rates in order to sustain a crew member with a failed Portable Life Support System (PLSS) during an Extravehicular Activity (EVA). A computational fluid dynamics evaluation was performed to estimate the helmet purge flow rate required to washout carbon dioxide and to prevent the condensing ("fogging") of water vapor on the helmet visor. An additional investigation predicted the suit purge flow rate required to provide sufficient convective cooling to keep the crew member comfortable. This paper summarizes the results of these evaluations.

  3. Exploration EVA Purge Flow Assessment

    NASA Technical Reports Server (NTRS)

    Navarro, Moses; Conger, Bruce

    2010-01-01

    An advanced future spacesuit will require properly sized suit and helmet purge flow rates in order to sustain a crew member with a failed Portable Life Support System (PLSS) during an Extravehicular Activity (EVA). A computational fluid dynamics evaluation was performed to estimate the helmet purge flow rate required to washout carbon dioxide and to prevent the condensing ("fogging") of water vapor on the helmet visor. An additional investigation predicted the suit purge flow rate required to provide sufficient convective cooling to keep the crew member comfortable. This paper summarizes the results of these evaluations.

  4. Advanced EVA system design requirements study: EVAS/space station system interface requirements

    NASA Technical Reports Server (NTRS)

    Woods, T. G.

    1985-01-01

    The definition of the Extravehicular Activity (EVA) systems interface requirements and accomodations for effective integration of a production EVA capability into the space station are contained. A description of the EVA systems for which the space station must provide the various interfaces and accomodations are provided. The discussion and analyses of the various space station areas in which the EVA interfaces are required and/or from which implications for EVA system design requirements are derived, are included. The rationale is provided for all EVAS mechanical, fluid, electrical, communications, and data system interfaces as well as exterior and interior requirements necessary to facilitate EVA operations. Results of the studies supporting these discussions are presented in the appendix.

  5. Advanced EVA system design requirements study

    NASA Technical Reports Server (NTRS)

    Woods, T. G.

    1988-01-01

    The results are presented of a study to identify specific criteria regarding space station extravehicular activity system (EVAS) hardware requirements. Key EVA design issues include maintainability, technology readiness, LSS volume vs. EVA time available, suit pressure/cabin pressure relationship and productivity effects, crew autonomy, integration of EVA as a program resource, and standardization of task interfaces. A variety of DOD EVA systems issues were taken into consideration. Recommendations include: (1) crew limitations, not hardware limitations; (2) capability to perform all of 15 generic missions; (3) 90 days on-orbit maintainability with 50 percent duty cycle as minimum; and (4) use by payload sponsors of JSC document 10615A plus a Generic Tool Kit and Specialized Tool Kit description. EVA baseline design requirements and criteria, including requirements of various subsystems, are outlined. Space station/EVA system interface requirements and EVA accommodations are discussed in the areas of atmosphere composition and pressure, communications, data management, logistics, safe haven, SS exterior and interior requirements, and SS airlock.

  6. EVA 2010: Preparing for International Space Station EVA Operations Post-Space Shuttle Retirement

    NASA Technical Reports Server (NTRS)

    Chullen, Cinda; West, William W.

    2010-01-01

    The expected retirement of the NASA Space Transportation System (also known as the Space Shuttle ) by 2011 will pose a significant challenge to Extra-Vehicular Activities (EVA) on-board the International Space Station (ISS). The EVA hardware currently used to assemble and maintain the ISS was designed assuming that it would be returned to Earth on the Space Shuttle for refurbishment, or if necessary for failure investigation. With the retirement of the Space Shuttle, a new concept of operations was developed to enable EVA hardware (Extra-vehicular Mobility Unit (EMU), Airlock Systems, EVA tools, and associated support hardware and consumables) to perform ISS EVAs until 2015, and possibly beyond to 2020. Shortly after the decision to retire the Space Shuttle was announced, the EVA 2010 Project was jointly initiated by NASA and the OneEVA contractor team. The challenges addressed were to extend the operating life and certification of EVA hardware, to secure the capability to launch EVA hardware safely on alternate launch vehicles, to protect for EMU hardware operability on-orbit, and to determine the source of high water purity to support recharge of PLSSs (no longer available via Shuttle). EVA 2010 Project includes the following tasks: the development of a launch fixture that would allow the EMU Portable Life Support System (PLSS) to be launched on-board alternate vehicles; extension of the EMU hardware maintenance interval from 3 years (current certification) to a minimum of 6 years (to extend to 2015); testing of recycled ISS Water Processor Assembly (WPA) water for use in the EMU cooling system in lieu of water resupplied by International Partner (IP) vehicles; development of techniques to remove & replace critical components in the PLSS on-orbit (not routine); extension of on-orbit certification of EVA tools; and development of an EVA hardware logistical plan to support the ISS without the Space Shuttle. Assumptions for the EVA 2010 Project included no more than

  7. EVA Wiki - Transforming Knowledge Management for EVA Flight Controllers and Instructors

    NASA Technical Reports Server (NTRS)

    Johnston, Stephanie S.; Alpert, Brian K.; Montalvo, Edwin James; Welsh, Lawrence Daren; Wray, Scott; Mavridis, Costa

    2016-01-01

    The EVA Wiki was recently implemented as the primary knowledge database to retain critical knowledge and skills in the EVA Operations group at NASA's Johnson Space Center by ensuring that information is recorded in a common, easy to search repository. Prior to the EVA Wiki, information required for EVA flight controllers and instructors was scattered across different sources, including multiple file share directories, SharePoint, individual computers, and paper archives. Many documents were outdated, and data was often difficult to find and distribute. In 2011, a team recognized that these knowledge management problems could be solved by creating an EVA Wiki using MediaWiki, a free and open-source software developed by the Wikimedia Foundation. The EVA Wiki developed into an EVA-specific Wikipedia on an internal NASA server. While the technical implementation of the wiki had many challenges, one of the biggest hurdles came from a cultural shift. Like many enterprise organizations, the EVA Operations group was accustomed to hierarchical data structures and individually-owned documents. Instead of sorting files into various folders, the wiki searches content. Rather than having a single document owner, the wiki harmonized the efforts of many contributors and established an automated revision controlled system. As the group adapted to the wiki, the usefulness of this single portal for information became apparent. It transformed into a useful data mining tool for EVA flight controllers and instructors, as well as hundreds of others that support EVA. Program managers, engineers, astronauts, flight directors, and flight controllers in differing disciplines now have an easier-to-use, searchable system to find EVA data. This paper presents the benefits the EVA Wiki has brought to NASA's EVA community, as well as the cultural challenges it had to overcome.

  8. EVA Wiki - Transforming Knowledge Management for EVA Flight Controllers and Instructors

    NASA Technical Reports Server (NTRS)

    Johnston, Stephanie S.; Alpert, Brian K.; Montalvo, Edwin James; Welsh, Lawrence Daren; Wray, Scott; Mavridis, Costa

    2016-01-01

    The EVA Wiki was recently implemented as the primary knowledge database to retain critical knowledge and skills in the EVA Operations group at NASA's Johnson Space Center by ensuring that information is recorded in a common, easy to search repository. Prior to the EVA Wiki, information required for EVA flight controllers and instructors was scattered across different sources, including multiple file share directories, SharePoint, individual computers, and paper archives. Many documents were outdated, and data was often difficult to find and distribute. In 2011, a team recognized that these knowledge management problems could be solved by creating an EVA Wiki using MediaWiki, a free and open-source software developed by the Wikimedia Foundation. The EVA Wiki developed into an EVA-specific Wikipedia on an internal NASA server. While the technical implementation of the wiki had many challenges, one of the biggest hurdles came from a cultural shift. Like many enterprise organizations, the EVA Operations group was accustomed to hierarchical data structures and individually-owned documents. Instead of sorting files into various folders, the wiki searches content. Rather than having a single document owner, the wiki harmonized the efforts of many contributors and established an automated revision controlled system. As the group adapted to the wiki, the usefulness of this single portal for information became apparent. It transformed into a useful data mining tool for EVA flight controllers and instructors, as well as hundreds of others that support the EVA. Program managers, engineers, astronauts, flight directors, and flight controllers in differing disciplines now have an easier-to-use, searchable system to find EVA data. This paper presents the benefits the EVA Wiki has brought to NASA's EVA community, as well as the cultural challenges it had to overcome.

  9. Walking to Olympus: An EVA Chronology

    NASA Technical Reports Server (NTRS)

    Portree, David S. F.; Trevino, Robert C.

    1997-01-01

    Spacewalkers enjoy a view of Earth once reserved for Apollo, Zeus, and other denizens of Mt. Olympus. During humanity's first extravehicular activity (EVA), Alexei Leonov floated above Gibraltar, the rock ancient seafarers saw as the gateway to the great unknown Atlantic. The symbolism was clear, Leonov stepped past a new Gibraltar when he stepped into space. More than 32 years and 154 EVAs later, Jerry Linenger conducted an EVA with Vladimir Tsibliyev as part of International Space Station Phase 1. They floated together above Gibraltar. Today the symbolism has new meaning: humanity is starting to think of stepping out of Earth orbit, space travel's new Gibraltar, and perhaps obtaining a new olympian view, a close-up look at Olympus Mons on Mars. Walking to Olympus: An EVA Chronology chronicles the 154 EVAs conducted from March 1965 to April 1997. It is intended to make clear the crucial role played by EVA in the history of spaceflight, as well as to chronicle the large body of EVA "lessons learned." Russia and the U.S. define EVA differently. Russian cosmonauts are said to perform EVA any time they are in vacuum in a space suit. A U.S. astronaut must have at least his head outside his spacecraft before he is said to perform an EVA. The difference is based in differing spacecraft design philoso- phies. Russian and Soviet spacecraft have always had a specialized airlock through which the EVA cosmonaut egressed, leaving the main habitable volume of the spacecraft pressurized. The U.S. Gemini and Apollo vehicles, on the other hand, depressurized their entire habitable volume for egress. In this document, we apply the Russian definition to Russian EVAS, and the U.S. definition to U.S. EVAS. Thus, for example, Gemini 4 Command Pilot James McDivitt does not share the honor of being first American spacewalker with Ed White, even though he was suited and in vacuum when White stepped out into space. Non-EVA spaceflights are listed in the chronology to provide context and to

  10. Software For Integration Of EVA And Telerobotics

    NASA Technical Reports Server (NTRS)

    Drews, Michael L.; Smith, Jeffrey H.; Estus, Jay M.; Heneghan, Cate; Zimmerman, Wayne; Fiorini, Paolo; Schenker, Paul S.; Mcaffee, Douglas A.

    1991-01-01

    Telerobotics/EVA Joint Analysis Systems (TEJAS) computer program is hypermedia information software system using object-oriented programming to bridge gap between crew-EVA and telerobotics activities. TEJAS Version 1.0 contains 20 HyperCard stacks using visual, customizable interface of icon buttons, pop-up menus, and relational commands to store, link, and standardize related information about primitives, technologies, tasks, assumptions, and open issues involved in space-telerobot or crew-EVA tasks. Runs on any Apple MacIntosh personal computer.

  11. EVA Suit Microbial Leakage Investigation Project

    NASA Technical Reports Server (NTRS)

    Falker, Jay; Baker, Christopher; Clayton, Ronald; Rucker, Michelle

    2016-01-01

    The objective of this project is to collect microbial samples from various EVA suits to determine how much microbial contamination is typically released during simulated planetary exploration activities. Data will be released to the planetary protection and science communities, and advanced EVA system designers. In the best case scenario, we will discover that very little microbial contamination leaks from our current or prototype suit designs, in the worst case scenario, we will identify leak paths, learn more about what affects leakage--and we'll have a new, flight-certified swab tool for our EVA toolbox.

  12. EVA Wiki - Transforming Knowledge Management for EVA Flight Controllers and Instructors

    NASA Technical Reports Server (NTRS)

    Johnston, Stephanie

    2016-01-01

    The EVA (Extravehicular Activity) Wiki was recently implemented as the primary knowledge database to retain critical knowledge and skills in the EVA Operations group at NASA's Johnson Space Center by ensuring that information is recorded in a common, searchable repository. Prior to the EVA Wiki, information required for EVA flight controllers and instructors was scattered across different sources, including multiple file share directories, SharePoint, individual computers, and paper archives. Many documents were outdated, and data was often difficult to find and distribute. In 2011, a team recognized that these knowledge management problems could be solved by creating an EVA Wiki using MediaWiki, a free and open-source software developed by the Wikimedia Foundation. The EVA Wiki developed into an EVA-specific Wikipedia on an internal NASA server. While the technical implementation of the wiki had many challenges, the one of the biggest hurdles came from a cultural shift. Like many enterprise organizations, the EVA Operations group was accustomed to hierarchical data structures and individually-owned documents. Instead of sorting files into various folders, the wiki searches content. Rather than having a single document owner, the wiki harmonized the efforts of many contributors and established an automated revision control system. As the group adapted to the wiki, the usefulness of this single portal for information became apparent. It transformed into a useful data mining tool for EVA flight controllers and instructors, and also for hundreds of other NASA and contract employees. Program managers, engineers, astronauts, flight directors, and flight controllers in differing disciplines now have an easier-to-use, searchable system to find EVA data. This paper presents the benefits the EVA Wiki has brought to NASA's EVA community, as well as the cultural challenges it had to overcome.

  13. Sustained release from hot-melt extruded matrices based on ethylene vinyl acetate and polyethylene oxide.

    PubMed

    Almeida, A; Brabant, L; Siepmann, F; De Beer, T; Bouquet, W; Van Hoorebeke, L; Siepmann, J; Remon, J P; Vervaet, C

    2012-11-01

    The aim of the present study was to evaluate the importance of matrix flexibility of hot-melt extruded (HME) ethylene vinyl acetate (EVA) matrices (with vinyl acetate (VA) contents of 9%, 15%, 28% and 40%), through the addition of hydrophilic polymers with distinct swelling capacity. Polyethylene oxide (PEO 100K, 1M and 7M) was used as swelling agent and metoprolol tartrate (MPT) as model drug. The processability via HME and drug release profiles of EVA/MPT/PEO formulations were assessed. Solid state characteristics, porosity and polymer miscibility of EVA/PEO matrices were evaluated by means of DSC, X-ray tomography and Raman spectroscopy. The processability via HME varied according to the VA content: EVA 40 and 28 were extruded at 90°C, whereas higher viscosity EVA grades (EVA 15 and 9) required a minimum extrusion temperature of 110°C to obtain high-quality extrudates. Drug release from EVA matrices depended on the VA content, PEO molecular weight and PEO content, matrix porosity as well as pore size distribution. Interestingly, the interplay of PEO leaching, matrix swelling, water influx and changes in matrix porosity influenced drug release: EVA 40- and 28-based matrices extruded with PEO of higher MW accelerated drug release, whereas for EVA 15- and 9-based matrices, drug release slowed down. These differences were related to the distinct polymer flexibility imposed by the VA content (lower VA content presents higher crystallinity and less free movement of the amorphous segments resulting in a higher rigidity). In all cases, diffusional mass transport seems to play a major role, as demonstrated by mathematical modeling using an analytical solution of Fick's second law. The bioavailability of EVA 40 and 28 matrices in dogs was not significantly different, independent of PEO 7M concentration.

  14. EVA Physiology, Systems and Performance [EPSP] Project

    NASA Technical Reports Server (NTRS)

    Gernhardt, Michael L.

    2010-01-01

    This viewgraph presentation gives a general overview of the biomedical and technological challenges of Extravehicular Activity (EVA). The topics covered include: 1) Prebreathe Protocols; 2) Lunar Suit Testing and Development; and 3) Lunar Electric Rover and Exploration Operations Concepts.

  15. Astronaut Bernard Harris on RMS during EVA

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Astronaut Bernard A. Harris, Jr., payload commander, watches astronaut C. Michael Foale (out of frame), mission specialist, during the late phases of their shared extravehicular activity (EVA) in the STS-63 Space Shuttle Discovery's cargo bay.

  16. Astronaut Bernard Harris on RMS during EVA

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Astronaut Bernard A. Harris, Jr., payload commander, standing on a foot restraint attached to the Remote Manipulator System (RMS) arm carries astronaut C. Michael Foale, mission specialist, during their shared extravehicular activity (EVA) in the Space Shuttle Discovery's cargo bay.

  17. EVA Health and Human Performance Benchmarking Study

    NASA Technical Reports Server (NTRS)

    Abercromby, A. F.; Norcross, J.; Jarvis, S. L.

    2016-01-01

    Multiple HRP Risks and Gaps require detailed characterization of human health and performance during exploration extravehicular activity (EVA) tasks; however, a rigorous and comprehensive methodology for characterizing and comparing the health and human performance implications of current and future EVA spacesuit designs does not exist. This study will identify and implement functional tasks and metrics, both objective and subjective, that are relevant to health and human performance, such as metabolic expenditure, suit fit, discomfort, suited postural stability, cognitive performance, and potentially biochemical responses for humans working inside different EVA suits doing functional tasks under the appropriate simulated reduced gravity environments. This study will provide health and human performance benchmark data for humans working in current EVA suits (EMU, Mark III, and Z2) as well as shirtsleeves using a standard set of tasks and metrics with quantified reliability. Results and methodologies developed during this test will provide benchmark data against which future EVA suits, and different suit configurations (eg, varied pressure, mass, CG) may be reliably compared in subsequent tests. Results will also inform fitness for duty standards as well as design requirements and operations concepts for future EVA suits and other exploration systems.

  18. Thallium acetate

    Integrated Risk Information System (IRIS)

    Jump to main content . Integrated Risk Information System Recent Additions | Contact Us Search : All EPA IRIS • You are here : EPA Home • Research • Environmental Assessment • IRIS • IRIS Summaries Redirect Page As of September 30 , 2009 , the assessment summary for Thallium acetate is included in t

  19. Phenylmercuric acetate

    Integrated Risk Information System (IRIS)

    Phenylmercuric acetate ; CASRN 62 - 38 - 4 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinog

  20. Ethyl acetate

    Integrated Risk Information System (IRIS)

    Ethyl acetate ; CASRN 141 - 78 - 6 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Eff

  1. Ammonium acetate

    Integrated Risk Information System (IRIS)

    Ammonium acetate ; CASRN 631 - 61 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  2. Vinyl acetate

    Integrated Risk Information System (IRIS)

    Vinyl acetate ; CASRN 108 - 05 - 4 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Eff

  3. Power assist EVA glove development

    NASA Technical Reports Server (NTRS)

    Main, John A.; Peterson, Steven W.; Strauss, Alvin M.

    1992-01-01

    Structural modeling of the EVA glove indicates that flexibility in the metacarpophalangeal (MCP) joint can be improved by selectively lowering the elasticity of the glove fabric. Two strategies are used to accomplish this. One method uses coil springs on the back of the glove to carry the tension in the glove skin due to pressurization. These springs carry the loads normally borne by the glove fabric, but are more easily deformed. An active system was also designed for the same purpose and uses gas filled bladders attached to the back of the EVA glove that change the dimensions of the back of the glove and allow the glove to bend at the MCP joint, thus providing greater flexibility at this joint. A threshold control scheme was devised to control the action of the joint actuators. Input to the controller was provided by thin resistive pressure sensors placed between the hand and the pressurized glove. The pressure sensors consist of a layer of polyester film that has a thin layer of ink screened on the surface. The resistivity of the ink is pressure dependent, so an extremely thin pressure sensor can be fabricated by covering the ink patch with another layer of polyester film and measuring the changing resistance of the ink with a bridge circuit. In order to sense the force between the hand and the glove at the MCP joint, a sensor was placed on the palmar face of the middle finger. The resultant signal was used by the controller to decide whether to fill or exhaust the bladder actuators on the back of the glove. The information from the sensor can also be used to evaluate the effectiveness of a given control scheme or glove design since the magnitude of the measured pressures gives some idea of the torque required to bend a glove finger at the MCP joint. Tests of this actuator, sensor, and control system were conducted in an 57.2 kPa glove box by performing a series of 90 degree finger bends with a glove without an MCP joint assembly, a glove with the coil spring

  4. Phase separations in a copolymer copolymer mixture

    NASA Astrophysics Data System (ADS)

    Zhang, Jin-Jun; Jin, Guojun; Ma, Yuqiang

    2006-01-01

    We propose a three-order-parameter model to study the phase separations in a diblock copolymer-diblock copolymer mixture. The cell dynamical simulations provide rich information about the phase evolution and structural formation, especially the appearance of onion-rings. The parametric dependence and physical reason for the domain growth of onion-rings are discussed.

  5. Examination of a Standardized Test for Evaluating the Degree of Cure of EVA Encapsulation (Presentation)

    SciTech Connect

    Miller, D.; Wohlgemuth, J.; Gu, X.; Haldeman, S.; Hidalgo, M.; Malguth, E.; Reid, C.; Shioda, T.; Schulze, S.; Wang, Z.

    2013-11-01

    The curing of cross-linkable encapsulation is a critical consideration for photovoltaic (PV) modules manufactured using a lamination process. Concerns related to ethylene-co-vinyl acetate (EVA) include the quality (e.g., expiration and uniformity) of the films or completion (duration) of the cross-linking of the EVA within a laminator. Because these issues are important to both EVA and module manufacturers, an international standard has recently been proposed by the Encapsulation Task-Group within the Working Group 2 (WG2) of the International Electrotechnical Commission (IEC) Technical Committee 82 (TC82) for the quantification of the degree of cure for EVA encapsulation. The present draft of the standard calls for the use of differential scanning calorimetry (DSC) as the rapid, enabling secondary (test) method. Both the residual enthalpy- and melt/freeze-DSC methods are identified. The DSC methods are calibrated against the gel content test, the primary (reference) method. Aspects of other established methods, including indentation and rotor cure metering, were considered by the group. Key details of the test procedure will be described.

  6. Examination of a Standardized Test for Evaluating the Degree of Cure of EVA Encapsulation: Preprint

    SciTech Connect

    Miller, D. C.; Gu, X.; Haldenman, S.; Hidalgo, M.; Malguth, E.; Reid, C. G.; Shioda, T.; Schulze, S. H.; Wang, Z. Y.; Wohlgemuth, J. H.

    2013-11-01

    The curing of cross-linkable encapsulation is a critical consideration for photovoltaic (PV) modules manufactured using a lamination process. Concerns related to ethylene-co-vinyl acetate (EVA) include the quality (e.g., expiration and uniformity) of the films or completion (duration) of the cross-linking of the EVA within a laminator. Because these issues are important to both EVA and module manufacturers, an international standard has recently been proposed by the Encapsulation Task-Group within the Working Group 2 (WG2) of the International Electrotechnical Commission (IEC) Technical Committee 82 (TC82) for the quantification of the degree of cure for EVA encapsulation. The present draft of the standard calls for the use of differential scanning calorimetry (DSC) as the rapid, enabling secondary (test) method. Both the residual enthalpy- and melt/freeze-DSC methods are identified. The DSC methods are calibrated against the gel content test, the primary (reference) method. Aspects of other established methods, including indentation and rotor cure metering, were considered by the group. Key details of the test procedure will be described.

  7. Applications of EVA guidelines and design criteria. Volume 3: EVA systems cost model formating

    NASA Technical Reports Server (NTRS)

    Brown, N. E.

    1973-01-01

    The development of a model for estimating the impact of manned EVA costs on future payloads is discussed. Basic information on the EV crewman requirements, equipment, physical and operational characteristics, and vehicle interfaces is provided. The cost model is being designed to allow system designers to quantify the impact of EVA on vehicle and payload systems.

  8. STS-110 Extravehicular Activity (EVA)

    NASA Technical Reports Server (NTRS)

    2002-01-01

    STS-110 Mission astronaut Rex J. Walheim, accompanied by astronaut Steven L. Smith (out of frame) translates along the Destiny laboratory on the International Space Station (ISS) during the third scheduled EVA session. The duo released the locking bolts on the Mobile Transporter and rewired the Station's robotic arm. The STS-110 mission prepared the ISS for future space walks by installing and outfitting the S0 (S-Zero) Truss and the Mobile Transporter. The 43-foot-long S0 truss weighing in at 27,000 pounds was the first of 9 segments that will make up the Station's external framework that will eventually stretch 356 feet (109 meters), or approximately the length of a football field. This central truss segment also includes a flatcar called the Mobile Transporter and rails that will become the first 'space railroad,' which will allow the Station's robotic arm to travel up and down the finished truss for future assembly and maintenance. The completed truss structure will hold solar arrays and radiators to provide power and cooling for additional international research laboratories from Japan and Europe that will be attached to the Station. Milestones of the S-110 mission included the first time the ISS robotic arm was used to maneuver space walkers around the Station and marked the first time all space walks were based out of the Station's Quest Airlock. It was also the first Shuttle to use three Block II Main Engines. The Space Shuttle Orbiter Atlantis, STS-110 mission, was launched April 8, 2002 and returned to Earth April 19, 2002.

  9. Influence of the association of the EVA and NBR on the characteristics of modified bitumen

    NASA Astrophysics Data System (ADS)

    Bensaada, A.; Soudani, K.; Haddadi, S.; Saoula, S.

    2015-03-01

    Durability and the performance of pavement depend mainly on the characteristics of materials which change over time like all other organic substances. They are subject to significant changes due to environmental conditions during the different phases of use. In the present work we investigated experimentally the influence of the association of ethyl vinyl acetate polymer (EVA) with an industrial waste, acrylonitrile-butadiene rubber (NBR) on the modification of bitumen AC 35-50 and its rheological behavior. The incorporation of NBR and EVA in the bitumen improved its intrinsic characteristics (softening point, penetration and ductility). In addition to improving the characteristics of bituminous binders that will affect the durability of bituminous structures, the environment will be preserved by the recycling of industrial waste.

  10. EVA/ORU model architecture using RAMCOST

    NASA Technical Reports Server (NTRS)

    Ntuen, Celestine A.; Park, Eui H.; Wang, Y. M.; Bretoi, R.

    1990-01-01

    A parametrically driven simulation model is presented in order to provide a detailed insight into the effects of various input parameters in the life testing of a modular space suit. The RAMCOST model employed is a user-oriented simulation model for studying the life-cycle costs of designs under conditions of uncertainty. The results obtained from the EVA simulated model are used to assess various mission life testing parameters such as the number of joint motions per EVA cycle time, part availability, and number of inspection requirements. RAMCOST first simulates EVA completion for NASA application using a probabilistic like PERT network. With the mission time heuristically determined, RAMCOST then models different orbital replacement unit policies with special application to the astronaut's space suit functional designs.

  11. Extravehicular Activity (EVA) Microbial Swab Tool

    NASA Technical Reports Server (NTRS)

    Rucker, Michelle

    2015-01-01

    When we send humans to search for life on Mars, we'll need to know what we brought with us versus what may already be there. To ensure our crewed spacecraft meet planetary protection requirements--and to protect our science from human contamination--we'll need to know whether micro-organisms are leaking/venting from our ships and spacesuits. This is easily done by swabbing external vents and surfaces for analysis, but there was no US EVA tool for that job. NASA engineers developed an EVA-compatible swab tool that can be used to collect data on current hardware, which will influence eventual Mars life support and EVA hardware designs.

  12. Creating a Lunar EVA Work Envelope

    NASA Technical Reports Server (NTRS)

    Griffin, Brand N.; Howard, Robert; Rajulu, Sudhakar; Smitherman, David

    2009-01-01

    A work envelope has been defined for weightless Extravehicular Activity (EVA) based on the Space Shuttle Extravehicular Mobility Unit (EMU), but there is no equivalent for planetary operations. The weightless work envelope is essential for planning all EVA tasks because it determines the location of removable parts, making sure they are within reach and visibility of the suited crew member. In addition, using the envelope positions the structural hard points for foot restraints that allow placing both hands on the job and provides a load path for reacting forces. EVA operations are always constrained by time. Tasks are carefully planned to ensure the crew has enough breathing oxygen, cooling water, and battery power. Planning first involves computers using a virtual work envelope to model tasks, next suited crew members in a simulated environment refine the tasks. For weightless operations, this process is well developed, but planetary EVA is different and no work envelope has been defined. The primary difference between weightless and planetary work envelopes is gravity. It influences anthropometry, horizontal and vertical mobility, and reaction load paths and introduces effort into doing "overhead" work. Additionally, the use of spacesuits other than the EMU, and their impacts on range of motion, must be taken into account. This paper presents the analysis leading to a concept for a planetary EVA work envelope with emphasis on lunar operations. There is some urgency in creating this concept because NASA has begun building and testing development hardware for the lunar surface, including rovers, habitats and cargo off-loading equipment. Just as with microgravity operations, a lunar EVA work envelope is needed to guide designers in the formative stages of the program with the objective of avoiding difficult and costly rework.

  13. Advanced EVA system design requirements study, executive summary

    NASA Technical Reports Server (NTRS)

    1986-01-01

    Design requirements and criteria for the space station advanced Extravehicular Activity System (EVAS) including crew enclosures, portable life support systems, maneuvering propulsion systems, and related EVA support equipment were established. The EVA mission requirements, environments, and medical and physiological requirements, as well as operational, procedures and training issues were considered.

  14. 21 CFR 177.1211 - Cross-linked polyacrylate copolymers.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...). The solvent used shall be at least 60 milliliters aqueous sodium chloride solution per gram of... grafted copolymer of cross-linked sodium polyacrylate identified as 2-propenoic acid, polymers with N,N-di-2-propenyl-2-propen-1-amine and hydrolyzed polyvinyl acetate, sodium salts, graft (CAS Reg....

  15. Protein based Block Copolymers

    PubMed Central

    Rabotyagova, Olena S.; Cebe, Peggy; Kaplan, David L.

    2011-01-01

    Advances in genetic engineering have led to the synthesis of protein-based block copolymers with control of chemistry and molecular weight, resulting in unique physical and biological properties. The benefits from incorporating peptide blocks into copolymer designs arise from the fundamental properties of proteins to adopt ordered conformations and to undergo self-assembly, providing control over structure formation at various length scales when compared to conventional block copolymers. This review covers the synthesis, structure, assembly, properties, and applications of protein-based block copolymers. PMID:21235251

  16. Effective Teamwork: The EVA NBL Experience

    NASA Technical Reports Server (NTRS)

    Crocker, Lori

    2007-01-01

    This viewgraph presentation reviews the experience of improving the operation of the ExtraVehiclar Activity (EVA) Neutral Buoyancy Laboratory as a team of NASA employees and contractors. It reviews specific recommendations to use in turning a struggling organization around as a NASA/contractor team

  17. Improved flexibility of an EVA glove

    NASA Technical Reports Server (NTRS)

    Eggeman, G. W.; Held, J. J.

    1986-01-01

    A student design contest was held between four universities. The project was to improve the flexibility of the NASA extra-vehicular activities (EVA) glove with the internal pressure increased from 4 psi to 8 psi. The Kansas State University team used an experimental design methodology and an industrial management scheme. This approach succeeded in making Kansas State University the winner of the competition.

  18. Astronaut Dale Gardner rehearses during EVA practice

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Astronaut Dale A. Gardner, 51-A mission specialist, rehearses control of manned maneuvering unit (MMU) during a practice for an extravehicular activity (EVA). Gardner is in the Shuttle mockup and integration laboratory at JSC. Gardner works to deploy a large stinger device designed for locking onto the orbiting satellites via entering a spent engine's nozzle.

  19. Astronaut Dale Gardner rehearses during EVA practice

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Astronaut Dale A. Gardner, 51-A mission specialist, rehearses control of manned maneuvering unit (MMU) during a practice for an extravehicular activity (EVA). Gardner is in the Shuttle mockup and integration laboratory at JSC. Gardner handles a stinger device to make initial contact with one of the two satellites they will be working with.

  20. Active personal radiation monitor for lunar EVA

    NASA Astrophysics Data System (ADS)

    Straume, Tore; Borak, Tom; Braby, L. A.; Lusby, Terry; Semones, Edward J.; Vazquez, Marcelo E.

    As astronauts return to the Moon-and this time, work for extended periods-there will be a critical need for crew personnel radiation monitoring as they operate lunar rovers or otherwise perform a myriad of extravehicular activities (EVAs). Our focus is on development of a small personal radiation monitor for lunar EVA that responds to the complex radiation quality and changing dose rates on the Moon. Of particular concern are active monitoring capabilities that provide both early warning and radiation dosimetry information during solar particle events (SPEs). To accomplish this, we are developing small detectors integrated with modern high speed, low power microelectronics to measure dose-rate and dose-mean lineal energy in real time. The monitor is designed to perform over the range of dose rates and LETs expected from both GCR and SPE radiations during lunar EVA missions. The monitor design provides simultaneous measurement of dose-equivalent rates at two tissue-equivalent depths simulating skin and marrow. The compact personal monitor is estimated to be the size of a cell phone and would fit on an EVA spacesuit (e.g., in backpack) or in a toolbox. The four-year development effort (which began December 2007) will result in a prototype radiation monitor field tested and characterized for the major radiations expected on the surface of the Moon. We acknowledge support from NSBRI through grants to NASA Ames Research Center (T. Straume, PI) and Colorado State University (T. Borak, PI).

  1. Crystallization and hardening of poly(ethylene-co-vinyl acetate) mouthguards during routine use

    PubMed Central

    Kuwahara, Ryoko; Tomita, Ryotaro; Ogawa, Natsumi; Nakajima, Kazunori; Takeda, Tomotaka; Uehara, Hiroki; Yamanobe, Takeshi

    2017-01-01

    Mouthguards (MGs) made from poly(ethylene-co-vinyl acetate) (EVA) are widely used in contact sports to prevent injuries such as breaking teeth and lip lacerations and to reduce brain concussion. However, the changes in morphology and the molecular mobility of EVA, which can affect its physical properties during practical usage, have not been precisely examined. Therefore, we attempted to determine the main factors which lead to changes in MG performance after one season of practical use by high school rugby players. Solid-state nuclear magnetic resonance (NMR) and pulse NMR measurements showed the hardening of MGs, which was associated with an increased crystallinity of the EVA resulting from prolonged usage. Furthermore, our data indicated that the increase in the relative amount of the crystalline phase may be primarily attributed to temperature fluctuations and repeated changes in pressure, which could cause the hardening of EVA and eventually diminish the protective ability of MGs. PMID:28294184

  2. Crystallization and hardening of poly(ethylene-co-vinyl acetate) mouthguards during routine use.

    PubMed

    Kuwahara, Ryoko; Tomita, Ryotaro; Ogawa, Natsumi; Nakajima, Kazunori; Takeda, Tomotaka; Uehara, Hiroki; Yamanobe, Takeshi

    2017-03-15

    Mouthguards (MGs) made from poly(ethylene-co-vinyl acetate) (EVA) are widely used in contact sports to prevent injuries such as breaking teeth and lip lacerations and to reduce brain concussion. However, the changes in morphology and the molecular mobility of EVA, which can affect its physical properties during practical usage, have not been precisely examined. Therefore, we attempted to determine the main factors which lead to changes in MG performance after one season of practical use by high school rugby players. Solid-state nuclear magnetic resonance (NMR) and pulse NMR measurements showed the hardening of MGs, which was associated with an increased crystallinity of the EVA resulting from prolonged usage. Furthermore, our data indicated that the increase in the relative amount of the crystalline phase may be primarily attributed to temperature fluctuations and repeated changes in pressure, which could cause the hardening of EVA and eventually diminish the protective ability of MGs.

  3. Preparing for space - EVA training at the European Astronaut Centre

    NASA Astrophysics Data System (ADS)

    Bolender, Hans; Stevenin, Hervé; Bessone, Loredana; Torres, Antonio

    2006-11-01

    The European Astronaut Centre has developed an Extra Vehicular Activity (EVA) training course for ESA astronauts to bridge the gap between their scuba diving certification and the spacesuit qualification provided by NASA. ESA astronauts André Kuipers and Frank De Winne have already completed this "EVA Pre-Familiarisation Training Programme" before their training at NASA. In June 2006, an international crew of experienced EVA astronauts approved the course as good preparation for suited EVA training; they recommended that portions of it be used to help maintain EVA proficiency for astronauts.

  4. CETA truck and EVA restraint system

    NASA Technical Reports Server (NTRS)

    Beals, David C.; Merson, Wayne R.

    1991-01-01

    The Crew Equipment Translation Aid (CETA) experiment is an extravehicular activity (EVA) Space Transportation System (STS) based flight experiment which will explore various modes of transporting astronauts and light equipment for Space Station Freedom (SSF). The basic elements of CETA are: (1) two 25 foot long sections of monorail, which will be EVA assembled in the STS cargo bay to become a single 50 ft. rail called the track; (2) a wheeled baseplate called the truck which rolls along the track and can accept three cart concepts; and (3) the three carts which are designated manual, electric, and mechanical. The three carts serve as the astronaut restraint and locomotive interfaces with the track. The manual cart is powered by the astronaut grasping the track's handrail and pulling himself along. The electric cart is operated by an astronaut turning a generator which powers the electric motor and drives the cart. The mechanical cart is driven by a Bendix type transmission and is similar in concept to a man-propelled railroad cart. During launch and landing, the truck is attached to the deployable track by means of EVA removable restraint bolts and held in position by a system of retractable shims. These shims are positioned on the exterior of the rail for launch and landing and rotate out of the way for the duration of the experiment. The shims are held in position by strips of Velcro nap, which rub against the sides of the shim and exert a tailored force. The amount of force required to rotate the shims was a major EVA concern, along with operational repeatability and extreme temperature effects. The restraint system was tested in a thermal-vac and vibration environment and was shown to meet all of the initial design requirements. Using design inputs from the astronauts who will perform the EVA, CETA evolved through an iterative design process and represented a cooperative effort.

  5. EVA Physiology and Medical Considerations Working in the Suit

    NASA Technical Reports Server (NTRS)

    Parazynski, Scott

    2012-01-01

    This "EVA Physiology and Medical Considerations Working in the Suit" presentation covers several topics related to the medical implications and physiological effects of suited operations in space from the perspective of a physician with considerable first-hand Extravehicular Activity (EVA) experience. Key themes include EVA physiology working in a pressure suit in the vacuum of space, basic EVA life support and work support, Thermal Protection System (TPS) inspections and repairs, and discussions of the physical challenges of an EVA. Parazynski covers the common injuries and significant risks during EVAs, as well as physical training required to prepare for EVAs. He also shares overall suit physiological and medical knowledge with the next generation of Extravehicular Mobility Unit (EMU) system designers.

  6. Dielectric properties of EVA rubber composites at microwave frequencies theory, instrumentation and measurements.

    PubMed

    Banerjee, Prasun; Biswas, Salil Kumar; Ghosh, Gautam

    2011-01-01

    This work describes and evaluates a technique for determining the dielectric properties of carbon-black filled Ethylene Vinyl Acetate (EVA) rubber and presents results on the studies of the effect of frequency on the permittivity and microwave conductivity using resonant cavity perturbation method. The measurements are performed with the aid of a Network Analyzer in X-band. The simplicity of this method lies in the fact that the dielectric properties can be obtained directly from the analytical formula without taking recourse to calibration.

  7. Silicone/Acrylate Copolymers

    NASA Technical Reports Server (NTRS)

    Dennis, W. E.

    1982-01-01

    Two-step process forms silicone/acrylate copolymers. Resulting acrylate functional fluid is reacted with other ingredients to produce copolymer. Films of polymer were formed by simply pouring or spraying mixture and allowing solvent to evaporate. Films showed good weatherability. Durable, clear polymer films protect photovoltaic cells.

  8. EVA-Compatible Microbial Swab Tool

    NASA Technical Reports Server (NTRS)

    Rucker, Michelle A.

    2016-01-01

    When we send humans to search for life on Mars, we'll need to know what we brought with us versus what may already be there. To ensure our crewed spacecraft meet planetary protection requirements—and to protect our science from human contamination—we'll need to know whether micro-organisms are leaking/venting from our ships and spacesuits. This is easily done by swabbing external vents and suit surfaces for analysis, but requires a specialized tool for the job. Engineers at the National Aeronautics and Space Administration (NASA) recently developed an Extravehicular Activity (EVA)-compatible swab tool that can be used to sample current space suits and life support systems. Data collected now will influence Mars life support and EVA hardware early in the planning process, before design changes become difficult and expensive.NASA’s EVA swab tool pairs a Space Shuttle-era tool handle with a commercially available swab tip mounted into a custom-designed end effector. A glove-compatible release mechanism allows the handle to quickly switch between swab tips, much like a shaving razor handle can snap onto a disposable blade cartridge. Swab tips are stowed inside individual sterile containers, each fitted with a microbial filter that allows the container to equalize atmospheric pressure, but prevents cabin contaminants from rushing into the container when passing from the EVA environment into a pressurized cabin. A bank of containers arrayed inside a tool caddy allows up to six individual samples to be collected during a given spacewalk.NASA plans to use the tool in 2016 to collect samples from various spacesuits during ground testing to determine what (if any) human-borne microbial contamination leaks from the suit under simulated thermal vacuum conditions. Next, the tool will be used on board the International Space Station to assess the types of microbial contaminants found on external environmental control and life support system vents. Data will support

  9. Fogging Control on LDPE/EVA Coextruded Films: Wettability Behavior and Its Correlation with Electric Performance

    PubMed Central

    Waldo-Mendoza, Miguel A.; Quiñones-Jurado, Zoe V.; Pérez-Medina, Juan C.; Yañez-Soto, Bernardo; Ramírez-González, Pedro E.

    2017-01-01

    The transformation of fog at a non-visible water layer on a membrane of low-density polyethylene (LDPE) and ethylene-vinyl acetate (EVA) was evaluated. Nonionic surfactants of major demand in the polyolefin industry were studied. A kinetic study using a hot fog chamber showed that condensation is controlled by both the diffusion and permanency of the surfactant more than by the change of the surface energy developed by the wetting agents. The greatest permanency of the anti-fog effect of the LDPE/EVA surface was close to 3000 h. The contact angle results demonstrated the ability of the wetting agent to spread out to the surface. Complementarily, the migration of nonionic surfactants from the inside of the polymeric matrix to the surface was analyzed by Fourier transform infrared (FTIR) microscopy. Additionally, electrical measurement on the anti-fogging membrane at alternating currents and at a sweep frequency was proposed to test the conductivity and wetting ability of nonionic surfactants. We proved that the amphiphilic molecules had the ability to increase the conductivity in the polyolefin membrane. A correlation between the bulk electrical conductivity and the permanency of the fogging control on the LDPE/EVA coextruded film was found. PMID:28241433

  10. Fogging Control on LDPE/EVA Coextruded Films: Wettability Behavior and Its Correlation with Electric Performance.

    PubMed

    Waldo-Mendoza, Miguel A; Quiñones-Jurado, Zoe V; Pérez-Medina, Juan C; Yañez-Soto, Bernardo; Ramírez-González, Pedro E

    2017-02-22

    The transformation of fog at a non-visible water layer on a membrane of low-density polyethylene (LDPE) and ethylene-vinyl acetate (EVA) was evaluated. Nonionic surfactants of major demand in the polyolefin industry were studied. A kinetic study using a hot fog chamber showed that condensation is controlled by both the diffusion and permanency of the surfactant more than by the change of the surface energy developed by the wetting agents. The greatest permanency of the anti-fog effect of the LDPE/EVA surface was close to 3000 h. The contact angle results demonstrated the ability of the wetting agent to spread out to the surface. Complementarily, the migration of nonionic surfactants from the inside of the polymeric matrix to the surface was analyzed by Fourier transform infrared (FTIR) microscopy. Additionally, electrical measurement on the anti-fogging membrane at alternating currents and at a sweep frequency was proposed to test the conductivity and wetting ability of nonionic surfactants. We proved that the amphiphilic molecules had the ability to increase the conductivity in the polyolefin membrane. A correlation between the bulk electrical conductivity and the permanency of the fogging control on the LDPE/EVA coextruded film was found.

  11. One hundred US EVAs: a perspective on spacewalks.

    PubMed

    Wilde, Richard C; McBarron, James W; Manatt, Scott A; McMann, Harold J; Fullerton, Richard K

    2002-01-01

    In the 36 years between June 1965 and February 2001, the US human space flight program has conducted 100 spacewalks, or extravehicular activities (EVAs), as NASA officially calls them. EVA occurs when astronauts wearing spacesuits travel outside their protective spacecraft to perform tasks in the space vacuum environment. US EVA started with pioneering feasibility tests during the Gemini Program. The Apollo Program required sending astronauts to the moon and performing EVA to explore the lunar surface. EVA supported scientific mission objectives of the Skylab program, but may be best remembered for repairing launch damage to the vehicle and thus saving the program. EVA capability on Shuttle was initially planned to be a kit that could be flown at will, and was primarily intended for coping with vehicle return emergencies. The Skylab emergency and the pivotal role of EVA in salvaging that program quickly promoted Shuttle EVA to an essential element for achieving mission objectives, including retrieving satellites and developing techniques to assemble and maintain the International Space Station (ISS). Now, EVA is supporting assembly of ISS. This paper highlights development of US EVA capability within the context of the overarching mission objectives of the US human space flight program.

  12. EVA assembly of large space structure element

    NASA Technical Reports Server (NTRS)

    Bement, L. J.; Bush, H. G.; Heard, W. L., Jr.; Stokes, J. W., Jr.

    1981-01-01

    The results of a test program to assess the potential of manned extravehicular activity (EVA) assembly of erectable space trusses are described. Seventeen tests were conducted in which six "space-weight" columns were assembled into a regular tetrahedral cell by a team of two "space"-suited test subjects. This cell represents the fundamental "element" of a tetrahedral truss structure. The tests were conducted under simulated zero-gravity conditions. Both manual and simulated remote manipulator system modes were evaluated. Articulation limits of the pressure suit and zero gravity could be accommodated by work stations with foot restraints. The results of this study have confirmed that astronaut EVA assembly of large, erectable space structures is well within man's capabilities.

  13. Skylab 3 crewmen practice EVA procedures

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The three prime crewmen of the Skylab 3 mission practice procedures which will be used during the extravehicular activity (EVA) portion of the scheduled Skylab rate gyro six-pac installation. They are Scientist-Astronaut Owen K. Garriott (center), Astronaut Alan L. Bean (center background) and Astronaut Jack R. Lousma (right). Garriott is working with a mock-up of a trunion plug plate which is on the space station's deployment assembly. This picture was taken during Skylab 3 prelaunch training at JSC. In the left foreground with back to camera is Astronaut Russell L. Schweickart, who is assisting with the Skylab 3 training. Another training officer is in the left background (31322); Lousma practices procedures for EVA in his extravehicular mobility unit (EMU). He is working with a mock-up of a trunion plug plate which is on the space station's deployment assembly (31323).

  14. The feasibility of Doppler monitoring during EVA.

    PubMed

    Barer, A; Filipenkov, S; Katuntsev, V; Vogt, L; Wenzel, J

    1995-07-01

    During extravehicular activities (EVA) outside the spacecraft, astronauts have to work under reduced pressure in a space suit. This pressure reduction induces the risk of decompression sickness (DCS) by the formation of gas bubbles from excess nitrogen dissolved in the organism by breathing air at normal pressure. Under laboratory conditions the gas bubbles moving in the blood stream can be detected by the non-invasive ultrasonic Doppler method. By early detection of excessive bubble formation the development of DCS symptoms may be prevented by early application of preventative measures. The method could also be useful when applied in the space suit in order to compare the results of laboratory tests with operational results, because there is a discrepancy according to the DCS risk of laboratory experiments and actual EVA missions, where no symptoms have been reported yet. A prototype Doppler sensor has been developed and implemented in the Russian Orlan suit. To investigate the feasibility of this method under simulated space conditions, the equipment has been used in a series of 12 thermovacuum chamber tests with suited subjects, where intravenous bubble formation was compared to unsuited control experiments. In more than 50% of the suited tests good Doppler recordings could be achieved. In some cases with unsatisfying results the signal could be improved by breathholding. Although the results do not yet allow any conclusion about a possible difference between suited and unsuited subjects due to the small number of tests performed, the method proved its feasibility for use in EVA suits and should be further developed to enhance the safety of EVA procedures.

  15. Eva Szabo, MD | Division of Cancer Prevention

    Cancer.gov

    Dr. Eva Szabo is Chief of the Lung and Upper Aerodigestive Cancer Research Group at the NCI Division of Cancer Prevention. She graduated from Yale University with a BS in Molecular Biophysics and Biochemistry, received her MD from Duke University, and completed her internal medicine residency at Bellevue-NYU Medical Center. After completing her medical oncology fellowship at the National Cancer Institute, Dr. |

  16. A Human Machine Interface for EVA

    NASA Astrophysics Data System (ADS)

    Hartmann, L.

    EVA astronauts work in a challenging environment that includes high rate of muscle fatigue, haptic and proprioception impairment, lack of dexterity and interaction with robotic equipment. Currently they are heavily dependent on support from on-board crew and ground station staff for information and robotics operation. They are limited to the operation of simple controls on the suit exterior and external robot controls that are difficult to operate because of the heavy gloves that are part of the EVA suit. A wearable human machine interface (HMI) inside the suit provides a powerful alternative for robot teleoperation, procedure checklist access, generic equipment operation via virtual control panels and general information retrieval and presentation. The HMI proposed here includes speech input and output, a simple 6 degree of freedom (dof) pointing device and a heads up display (HUD). The essential characteristic of this interface is that it offers an alternative to the standard keyboard and mouse interface of a desktop computer. The astronaut's speech is used as input to command mode changes, execute arbitrary computer commands and generate text. The HMI can respond with speech also in order to confirm selections, provide status and feedback and present text output. A candidate 6 dof pointing device is Measurand's Shapetape, a flexible "tape" substrate to which is attached an optic fiber with embedded sensors. Measurement of the modulation of the light passing through the fiber can be used to compute the shape of the tape and, in particular, the position and orientation of the end of the Shapetape. It can be used to provide any kind of 3d geometric information including robot teleoperation control. The HUD can overlay graphical information onto the astronaut's visual field including robot joint torques, end effector configuration, procedure checklists and virtual control panels. With suitable tracking information about the position and orientation of the EVA suit

  17. Collaborative Human Engineering Work in Space Exploration Extravehicular Activities (EVA)

    NASA Technical Reports Server (NTRS)

    DeSantis, Lena; Whitmore, Mihriban

    2007-01-01

    A viewgraph presentation on extravehicular activities in space exploration in collaboration with other NASA centers, industries, and universities is shown. The topics include: 1) Concept of Operations for Future EVA activities; 2) Desert Research and Technology Studies (RATS); 3) Advanced EVA Walkback Test; 4) Walkback Subjective Results; 5) Integrated Suit Test 1; 6) Portable Life Support Subsystem (PLSS); 7) Flex PLSS Design Process; and 8) EVA Information System; 9)

  18. Astronaut Jack Lousma seen outside Skylab space station during EVA

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Astronaut Jack R. Lousma, Skylab 3 pilot, is seen outside the Skylab space station in Earth orbit during the August 5, 1973 Skylab 3 extravehicular activity (EVA) in this photographic reproduction taken from a television transmission made by a color TV camera aboard the space station. Scientist-Astronaut Owen K. Garriott, Skylab 3 science pilot, participated in the EVA with Lousma. During the EVA the two crewmen deployed the twin pole solar shield to help shade the Orbital Workshop.

  19. Eva Physiology, Systems, and Performance (EPSP) Project Overview

    NASA Technical Reports Server (NTRS)

    Gernhardt, Michael L.

    2007-01-01

    Extravehicular activity (EVA) is any activity performed by astronauts outside their space vehicle or habitat. EVA may be performed on orbit, such as outside the Space Shuttle or the International Space Station, or on a planetary surface such as Mars or on the moon. Astronauts wear a pressurized suit that provides environmental protection, mobility, life support, and communications while they work in the harsh conditions of a microgravity environment. Exploration missions to the moon and Mars may last many days and will include many types of EVAs; exploration, science, construction and maintenance. The effectiveness and success of these EVA-filled missions is dependent on the ability to perform tasks efficiently. The EVA Physiology, Systems and Performance (EPSP) project will conduct a number of studies to understand human performance during EVA, from a molecular level to full-scale equipment and suit design aspects, with the aim of developing safe and efficient systems for Exploration missions and the Constellation Program. The EPSP project will 1) develop Exploration Mission EVA suit requirements for metabolic and thermal loading, optional center of gravity location, biomedical sensors, hydration, nutrition, and human biomedical interactions; 2) develop validated EVA prebreathe protocols that meet medical, vehicle, and habitat constraints while minimizing crew time and thus increasing EVA work efficiency; and 3) define exploration decompression sickness (DCS) risks, policy, and mission success statistics and develop a DCS risk definition report.

  20. EVA - Don't Leave Earth Without It

    NASA Technical Reports Server (NTRS)

    Cupples, J. Scott; Smith, Stephen A.

    2011-01-01

    Modern manned space programs come in two categories: those that need Extravehicular Activity (EVA) and those that will need EVA. This paper discusses major milestones in the Shuttle Program where EVA was used to save payloads, enhance on-orbit capabilities, and build structures in order to ensure success of National Aeronautics and Space Administration (NASA) missions. In conjunction, the Extravehicular Mobility Unit s (EMU) design, and hence, its capabilities evolved as its mission evolved. It is the intent that lessons can be drawn from these case studies so that EVA compatibility is designed into future vehicles and payloads.

  1. Controlled release of 5-fluorouridine from radiation-crosslinked poly(ethylene-co-vinyl acetate) films.

    PubMed

    de Queiroz, Alvaro A A; Abraham, Gustavo A; Higa, Olga Zazuco

    2006-11-01

    The effect of gamma-radiation doses of 12.5-380 kGy on the infrared spectra, gel content, mechanical properties, and the release of oxobutyl-5-fluoro-2'-deoxyuridine (OfdUrd, an antitumor agent) from poly(ethylene-co-vinyl acetate) (EVA) films was studied. The results showed that the application of radiation doses produced a crosslinking reaction leading to a maximum gel content of about 85% in the case of 150 kGy. Higher doses did not increase the gel content in EVA films. The mechanical properties (tensile strength, percentage elongation at break and Young's modulus) of all studied EVA matrices were affected by the exposure to gamma-radiation. Irradiation doses over 50 kGy caused an increase in the Young's modulus of EVA and at the same time a decrease in the strain per cent. Moreover, the network structure formed after irradiation reduced significantly the OFdUrd release from EVA films. In this manner, the radiation dose applied to the polymeric matrix modulated the release of OFdUrd, avoiding the high concentrations that may cause severe systemic toxicity. The loading of OFdUrd to EVA film triggered a slight hyperemia after implantation, while the inflammatory reaction was only observed during the first two days.

  2. Enhanced controlled release of loratadine from the ethylene-vinyl acetate matrix containing plasticizer.

    PubMed

    Cho, Cheong-Weon; Kim, Seong-Jin; Yang, Kyu-Ho; Song, Jae-Haeng; Jeong, Hyun-Jon; Shin, Sang-Chul

    2008-09-01

    An ethylene-vinyl acetate (EVA) matrix containing plasticizer was prepared as a potential controlled release system for loratadine. The EVA matrix containing loratadine was prepared as the transdermal device using casting methods. The solubility of loratadine according to the volume fraction of PEG 400 was determined. The effects of the drug concentration, temperature, and plasticizers on the release of the drug were determined at 37 degrees C using 40% PEG 400 solution as the receptor medium using the modified Keshary-Chien cell. Some types of plasticizers. such as citrates and phthalates, were used to prepare the pores and increase the flexibility of the EVA matrix. The solubility test according to the PEG 400 volume fraction revealed the highest solubility in the 40% PEG 400 solution. The rate of drug released from the EVA matrix increased with increasing temperature and drug loading. There was a linear relationship between the release rate and the square root of the loading dose. The activation energy for drug release from the EVA matrix with a loading dose of 1%, 2%, 3%, 4%, and 5% was estimated to be 6.83, 6.80, 6.77, 6.71, and 6.65 kcal/mol, respectively Among the plasticizers used, diethyl phthalate showed the highest level of loratadine release. In conclusion, an EVA matrix containing plasticizer could be used to enhance the controlled release of loratadine.

  3. The odontological identification of Eva Braun Hitler.

    PubMed

    Keiser-Nielsen, S; Strøm, F

    1983-01-01

    On May 7th-9th, 1945, a team of Russian pathologists autopsied several bodies found in and near the Fuehrer Bunker in Berlin; among them, a female body (No. 13) was later identified as that of Eva Braun Hitler (EBH), mainly by means of a gold bridge from the lower right jaw. A postmortem photograph of this bridge also shows a separate gold filling. Data now available on the dental treatment of EBH have permitted the present authors to substantiate that this gold filling also came from the mouth of EBH. Further speculation about the fate of EBH would henceforth seem professionally unfounded.

  4. A human factors analysis of EVA time requirements

    NASA Technical Reports Server (NTRS)

    Pate, D. W.

    1996-01-01

    Human Factors Engineering (HFE), also known as Ergonomics, is a discipline whose goal is to engineer a safer, more efficient interface between humans and machines. HFE makes use of a wide range of tools and techniques to fulfill this goal. One of these tools is known as motion and time study, a technique used to develop time standards for given tasks. A human factors motion and time study was initiated with the goal of developing a database of EVA task times and a method of utilizing the database to predict how long an ExtraVehicular Activity (EVA) should take. Initial development relied on the EVA activities performed during the STS-61 mission (Hubble repair). The first step of the analysis was to become familiar with EVAs and with the previous studies and documents produced on EVAs. After reviewing these documents, an initial set of task primitives and task time modifiers was developed. Videotaped footage of STS-61 EVAs were analyzed using these primitives and task time modifiers. Data for two entire EVA missions and portions of several others, each with two EVA astronauts, was collected for analysis. Feedback from the analysis of the data will be used to further refine the primitives and task time modifiers used. Analysis of variance techniques for categorical data will be used to determine which factors may, individually or by interactions, effect the primitive times and how much of an effect they have.

  5. Compiling a Comprehensive EVA Training Dataset for NASA Astronauts

    NASA Technical Reports Server (NTRS)

    Laughlin, M. S.; Murry, J. D.; Lee, L. R.; Wear, M. L.; Van Baalen, M.

    2016-01-01

    Training for a spacewalk or extravehicular activity (EVA) is considered hazardous duty for NASA astronauts. This activity places astronauts at risk for decompression sickness as well as various musculoskeletal disorders from working in the spacesuit. As a result, the operational and research communities over the years have requested access to EVA training data to supplement their studies.

  6. Astronaut David Scott practicing for Gemini 8 EVA

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Astronaut David R. Scott practicing for Gemini 8 extravehicular acitivity (EVA) in bldg 4 of the Manned Spacecraft Center on the air bearing floor. He is wearing the the Hand-Held Maneuvering Unit which he will use during the EVA.

  7. Extravehicular Activity System Sizing Analysis Tool (EVAS_SAT)

    NASA Technical Reports Server (NTRS)

    Brown, Cheryl B.; Conger, Bruce C.; Miranda, Bruno M.; Bue, Grant C.; Rouen, Michael N.

    2007-01-01

    An effort was initiated by NASA/JSC in 2001 to develop an Extravehicular Activity System Sizing Analysis Tool (EVAS_SAT) for the sizing of Extravehicular Activity System (EVAS) architecture and studies. Its intent was to support space suit development efforts and to aid in conceptual designs for future human exploration missions. Its basis was the Life Support Options Performance Program (LSOPP), a spacesuit and portable life support system (PLSS) sizing program developed for NASA/JSC circa 1990. EVAS_SAT estimates the mass, power, and volume characteristics for user-defined EVAS architectures, including Suit Systems, Airlock Systems, Tools and Translation Aids, and Vehicle Support equipment. The tool has undergone annual changes and has been updated as new data have become available. Certain sizing algorithms have been developed based on industry standards, while others are based on the LSOPP sizing routines. The sizing algorithms used by EVAS_SAT are preliminary. Because EVAS_SAT was designed for use by members of the EVA community, subsystem familiarity on the part of the intended user group and in the analysis of results is assumed. The current EVAS_SAT is operated within Microsoft Excel 2003 using a Visual Basic interface system.

  8. Astronaut Dale Gardner holds up for sale sign after EVA

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Astronaut Dale A. Gardner, having just completed the major portion of his second extravehicular activity (EVA) period in three days, holds up a 'for sale' sign. Astronaut Joseph P. ALlen IV, who also participated in the two EVA's, is reflected in Gardner's helmet visor. A portion of each of two recovered satellites is in the lower right corner, with Westar nearer Discovery's aft.

  9. Astronaut hazard during free-flight polar EVA

    NASA Technical Reports Server (NTRS)

    Hall, W. N.

    1985-01-01

    Extravehicular Activity (EVA) during Shuttle flights planned for the late 1980's includes several factors which together may constitute an astronaut hazard. Free-flight EVA is planned whereas prior United States Earth orbit EVA has used umbilical tethers carrying communications, coolant, and oxygen. EVA associated with missions like LANDSAT Retrieval will be in orbits through the auroral oval where charging of spacecraft may occur. The astronaut performing free flight EVA constitutes an independent spacecraft. The astronaut and the Shuttle make up a system of electrically isolated spacecraft with a wide disparity in size. Unique situations, such as the astronaut being in the wake of the Shuttle while traversing an auroral disturbance, could result in significant astronaut and Shuttle charging. Charging and subsequent arc discharge are important because they have been associated with operating upsets and even satellite failure at geosynchronous orbit. Spacecraft charging theory and experiments are examined to evaluate charging for Shuttle size spacecraft in the polar ionosphere.

  10. Experiments with an EVA Assistant Robot

    NASA Technical Reports Server (NTRS)

    Burridge, Robert R.; Graham, Jeffrey; Shillcutt, Kim; Hirsh, Robert; Kortenkamp, David

    2003-01-01

    Human missions to the Moon or Mars will likely be accompanied by many useful robots that will assist in all aspects of the mission, from construction to maintenance to surface exploration. Such robots might scout terrain, carry tools, take pictures, curate samples, or provide status information during a traverse. At NASA/JSC, the EVA Robotic Assistant (ERA) project has developed a robot testbed for exploring the issues of astronaut-robot interaction. Together with JSC's Advanced Spacesuit Lab, the ERA team has been developing robot capabilities and testing them with space-suited test subjects at planetary surface analog sites. In this paper, we describe the current state of the ERA testbed and two weeks of remote field tests in Arizona in September 2002. A number of teams with a broad range of interests participated in these experiments to explore different aspects of what must be done to develop a program for robotic assistance to surface EVA. Technologies explored in the field experiments included a fuel cell, new mobility platform and manipulator, novel software and communications infrastructure for multi-agent modeling and planning, a mobile science lab, an "InfoPak" for monitoring the spacesuit, and delayed satellite communication to a remote operations team. In this paper, we will describe this latest round of field tests in detail.

  11. Active Solid State Dosimetry for Lunar EVA

    NASA Technical Reports Server (NTRS)

    Wrbanek, John D.; Fralick, Gustave C.; Wrbanek, Susan Y.; Chen, Liang-Yu.

    2006-01-01

    The primary threat to astronauts from space radiation is high-energy charged particles, such as electrons, protons, alpha and heavier particles, originating from galactic cosmic radiation (GCR), solar particle events (SPEs) and trapped radiation belts in Earth orbit. There is also the added threat of secondary neutrons generated as the space radiation interacts with atmosphere, soil and structural materials.[1] For Lunar exploration missions, the habitats and transfer vehicles are expected to provide shielding from standard background radiation. Unfortunately, the Lunar Extravehicular Activity (EVA) suit is not expected to afford such shielding. Astronauts need to be aware of potentially hazardous conditions in their immediate area on EVA before a health and hardware risk arises. These conditions would include fluctuations of the local radiation field due to changes in the space radiation field and unknown variations in the local surface composition. Should undue exposure occur, knowledge of the dynamic intensity conditions during the exposure will allow more precise diagnostic assessment of the potential health risk to the exposed individual.[2

  12. STS-112 Astronaut Wolf Participates in EVA

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Astronaut David A. Wolf, STS-112 mission specialist, participates in the mission's second session of extravehicular activity (EVA), a six hour, four minute space walk, in which an exterior station television camera was installed outside of the Destiny Laboratory. Launched October 7, 2002 aboard the Space Shuttle Orbiter Atlantis, the STS-112 mission lasted 11 days and performed three EVA sessions. Its primary mission was to install the Starboard (S1) Integrated Truss Structure and Equipment Translation Aid (CETA) Cart to the International Space Station (ISS). The S1 truss provides structural support for the orbiting research facility's radiator panels, which use ammonia to cool the Station's complex power system. The S1 truss, attached to the S0 (S Zero) truss installed by the previous STS-110 mission, flows 637 pounds of anhydrous ammonia through three heat rejection radiators. The truss is 45-feet long, 15-feet wide, 10-feet tall, and weighs approximately 32,000 pounds. The CETA is the first of two human-powered carts that will ride along the International Space Station's railway providing a mobile work platform for future extravehicular activities by astronauts.

  13. STS-112 Astronaut Wolf Participates in EVA

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Anchored to a foot restraint on the Space Station Remote Manipulator System (SSRMS) or Canadarm2, astronaut David A. Wolf, STS-112 mission specialist, participates in the mission's first session of extravehicular activity (EVA). Wolf is carrying the Starboard One (S1) outboard nadir external camera which was installed on the end of the S1 Truss on the International Space Station (ISS). Launched October 7, 2002 aboard the Space Shuttle Orbiter Atlantis, the STS-112 mission lasted 11 days and performed three EVAs. Its primary mission was to install the S1 Integrated Truss Structure and Equipment Translation Aid (CETA) Cart to the ISS. The S1 truss provides structural support for the orbiting research facility's radiator panels, which use ammonia to cool the Station's complex power system. The S1 truss, attached to the S0 (S Zero) truss installed by the previous STS-110 mission, flows 637 pounds of anhydrous ammonia through three heat rejection radiators. The truss is 45-feet long, 15-feet wide, 10-feet tall, and weighs approximately 32,000 pounds. The CETA is the first of two human-powered carts that will ride along the International Space Station's railway providing a mobile work platform for future extravehicular activities by astronauts.

  14. The EVA space suit development in Europe

    NASA Astrophysics Data System (ADS)

    Skoog, A. Ingemar

    The progress of the European EVA space suit predevelopment activities has resulted in an improved technical reference concept, which will form the basis for a start of the Phase C/D development work in 1992. Technology development work over the last 2 years has resulted in a considerable amount of test data and a better understanding of the characteristics and behaviour of individual parts of the space suit system, in particular in the areas of suits' mobility and life support functions. This information has enabled a consolidation of certain design features on the one hand, but also led to the challenging of some of the design solutions on the other hand. While working towards an improved situation with respect to the main design drivers mass and cost, the technical concept has been improved with respect to functional safety and ease of handling, taking the evolving Hermes spaceplane requirements into consideration. Necessary hardware and functional redundancies have been implemented taking the operational scenario with Hermes and Columbus servicing into consideration. This paper presents the latest design status of the European EVA space suit concept, with particular emphasis on crew safety, comfort and productivity, in the frame of the predevelopment work for the European Space Agency.

  15. Use MACES IVA Suit for EVA Mobility Evaluations

    NASA Technical Reports Server (NTRS)

    Watson, Richard D.

    2014-01-01

    The use of an Intra-Vehicular Activity (IVA) suit for a spacewalk or Extra-Vehicular Activity (EVA) was evaluated for mobility and usability in the Neutral Buoyancy Lab (NBL) environment. The Space Shuttle Advanced Crew Escape Suit (ACES) has been modified (MACES) to integrate with the Orion spacecraft. The first several missions of the Orion MPCV spacecraft will not have mass available to carry an EVA specific suit so any EVA required will have to be performed by the MACES. Since the MACES was not designed with EVA in mind, it was unknown what mobility the suit would be able to provide for an EVA or if a person could perform useful tasks for an extended time inside the pressurized suit. The suit was evaluated in multiple NBL runs by a variety of subjects including crewmembers with significant EVA experience. Various functional mobility tasks performed included: translation, body positioning, carrying tools, body stabilization, equipment handling, and use of tools. Hardware configurations included with and without TMG, suit with IVA gloves and suit with EVA gloves. Most tasks were completed on ISS mockups with existing EVA tools. Some limited tasks were completed with prototype tools on a simulated rocky surface. Major findings include: demonstration of the ability to weigh-out the suit, understanding the need to have subjects perform multiple runs prior to getting feedback, determination of critical sizing factors, and need for adjustment of suit work envelop. The early testing has demonstrated the feasibility of EVA's limited duration and limited scope. Further testing is required with more flight like tasking and constraints to validate these early results. If the suit is used for EVA, it will require mission specific modifications for umbilical management or PLSS integration, safety tether attachment, and tool interfaces. These evaluations are continuing through calendar year 2014.

  16. Advanced EVA Suit Camera System Development Project

    NASA Technical Reports Server (NTRS)

    Mock, Kyla

    2016-01-01

    The National Aeronautics and Space Administration (NASA) at the Johnson Space Center (JSC) is developing a new extra-vehicular activity (EVA) suit known as the Advanced EVA Z2 Suit. All of the improvements to the EVA Suit provide the opportunity to update the technology of the video imagery. My summer internship project involved improving the video streaming capabilities of the cameras that will be used on the Z2 Suit for data acquisition. To accomplish this, I familiarized myself with the architecture of the camera that is currently being tested to be able to make improvements on the design. Because there is a lot of benefit to saving space, power, and weight on the EVA suit, my job was to use Altium Design to start designing a much smaller and simplified interface board for the camera's microprocessor and external components. This involved checking datasheets of various components and checking signal connections to ensure that this architecture could be used for both the Z2 suit and potentially other future projects. The Orion spacecraft is a specific project that may benefit from this condensed camera interface design. The camera's physical placement on the suit also needed to be determined and tested so that image resolution can be maximized. Many of the options of the camera placement may be tested along with other future suit testing. There are multiple teams that work on different parts of the suit, so the camera's placement could directly affect their research or design. For this reason, a big part of my project was initiating contact with other branches and setting up multiple meetings to learn more about the pros and cons of the potential camera placements we are analyzing. Collaboration with the multiple teams working on the Advanced EVA Z2 Suit is absolutely necessary and these comparisons will be used as further progress is made for the overall suit design. This prototype will not be finished in time for the scheduled Z2 Suit testing, so my time was

  17. Augmented robotic device for EVA hand manoeuvres

    NASA Astrophysics Data System (ADS)

    Matheson, Eloise; Brooker, Graham

    2012-12-01

    During extravehicular activities (EVAs), pressurised space suits can lead to difficulties in performing hand manoeuvres and fatigue. This is often the cause of EVAs being terminated early, or taking longer to complete. Assistive robotic gloves can be used to augment the natural motion of a human hand, meaning work can be carried out more efficiently with less stress to the astronaut. Lightweight and low profile solutions must be found in order for the assistive robotic glove to be easily integrated with a space suit pressure garment. Pneumatic muscle actuators combined with force sensors are one such solution. These actuators are extremely light, yet can output high forces using pressurised gases as the actuation drive. Their movement is omnidirectional, so when combined with a flexible exoskeleton that itself provides a degree of freedom of movement, individual fingers can be controlled during flexion and extension. This setup allows actuators and other hardware to be stored remotely on the user's body, resulting in the least possible mass being supported by the hand. Two prototype gloves have been developed at the University of Sydney; prototype I using a fibreglass exoskeleton to provide flexion force, and prototype II using torsion springs to achieve the same result. The gloves have been designed to increase the ease of human movements, rather than to add unnatural ability to the hand. A state space control algorithm has been developed to ensure that human initiated movements are recognised, and calibration methods have been implemented to accommodate the different characteristics of each wearer's hands. For this calibration technique, it was necessary to take into account the natural tremors of the human hand which may have otherwise initiated unexpected control signals. Prototype I was able to actuate the user's hand in 1 degree of freedom (DOF) from full flexion to partial extension, and prototype II actuated a user's finger in 2 DOF with forces achieved

  18. Genomic characterization of two new enterovirus types, EV-A114 and EV-A121.

    PubMed

    Deshpande, Jagadish M; Sharma, Deepa K; Saxena, Vinay K; Shetty, Sushmitha A; Qureshi, Tarique Husain I H; Nalavade, Uma P

    2016-12-01

    Enteroviruses cause a variety of illnesses of the gastrointestinal tract, central nervous system and cardiovascular system. Phylogenetic analysis of VP1 sequences has identified 106 different human enteroviruses classified into four enterovirus species within the genus Enterovirus of the family Picornaviridae. It is likely that not all enterovirus types have been discovered. Between September 2013 and October 2014, stool samples of 6274 apparently healthy children of up to 5 years of age residing in Gorakhpur district, Uttar Pradesh, India were screened for enteroviruses. Virus isolates obtained in RD and Hep-2c cells were identified by complete VP1 sequencing. Enteroviruses were isolated from 3042 samples. A total of 87 different enterovirus types were identified. Two isolates with 71 and 74 % nucleotide sequence similarity to all other known enteroviruses were recognized as novel types. In this paper we report identification and complete genome sequence analysis of these two isolates classified as EV-A114 and EV-A121.

  19. Application of EVA guidelines and design criteria. Volume 1: EVA selection/systems design considerations

    NASA Technical Reports Server (NTRS)

    Brown, N. E.

    1973-01-01

    Parameters that require consideration by the planners and designers when planning for man to perform functions outside the vehicle are presented in terms of the impact the extravehicular crewmen and major EV equipment items have on the mission, vehicle, and payload. Summary data on man's performance capabilities in the weightless space environment are also provided. The performance data are based on orbital and transearth EVA from previous space flight programs and earthbound simulations, such as water immersion and zero-g aircraft.

  20. Application of EVA guidelines and design criteria. Volume 2: EVA workstation conceptual designs

    NASA Technical Reports Server (NTRS)

    Brown, N. E.

    1973-01-01

    Several EV workstation concepts were developed and are documented. The workstation concepts were developed following a comprehensive analysis of potential EV missions, functions, and tasks as interpreted from NASA and contractor space shuttle and space station studies, mission models, and related reports. The design of a versatile, portable EVA workstation is aimed at reducing the design and development costs for each mission and aiding in the development of on-orbit serviceable payloads.

  1. Ultraviolet absorbing copolymers

    DOEpatents

    Gupta, Amitava; Yavrouian, Andre H.

    1982-01-01

    Photostable and weather stable absorping copolymers have been prepared from acrylic esters such as methyl methacrylate containing 0.1 to 5% of an 2-hydroxy-allyl benzophenone, preferably the 4,4' dimethoxy derivative thereof. The pendant benzophenone chromophores protect the acrylic backbone and when photoexcited do not degrade the ester side chain, nor abstract hydrogen from the backbone.

  2. Block coordination copolymers

    DOEpatents

    Koh, Kyoung Moo; Wong-Foy, Antek G.; Matzger, Adam J.; Benin, Annabelle I.; Willis, Richard R.

    2012-12-04

    The present invention provides compositions of crystalline coordination copolymers wherein multiple organic molecules are assembled to produce porous framework materials with layered or core-shell structures. These materials are synthesized by sequential growth techniques such as the seed growth technique. In addition, the invention provides a simple procedure for controlling functionality.

  3. Block coordination copolymers

    DOEpatents

    Koh, Kyoung Moo; Wong-Foy, Antek G; Matzger, Adam J; Benin, Annabelle I; Willis, Richard R

    2012-11-13

    The present invention provides compositions of crystalline coordination copolymers wherein multiple organic molecules are assembled to produce porous framework materials with layered or core-shell structures. These materials are synthesized by sequential growth techniques such as the seed growth technique. In addition, the invention provides a simple procedure for controlling functionality.

  4. Block coordination copolymers

    DOEpatents

    Koh, Kyoung Moo; Wong-Foy, Antek G; Matzger, Adam J; Benin, Annabelle I; Willis, Richard R

    2014-11-11

    The present invention provides compositions of crystalline coordination copolymers wherein multiple organic molecules are assembled to produce porous framework materials with layered or core-shell structures. These materials are synthesized by sequential growth techniques such as the seed growth technique. In addition, the invention provides a simple procedure for controlling functionality.

  5. Astronaut Noriega During Extravehicular Activity (EVA)

    NASA Technical Reports Server (NTRS)

    2000-01-01

    In this image, STS-97 astronaut and mission specialist Carlos I. Noriega waves at a crew member inside Endeavor's cabin during the mission's final session of Extravehicular Activity (EVA). Launched aboard the Space Shuttle Orbiter Endeavor on November 30, 2000, the STS-97 mission's primary objective was the delivery, assembly, and activation of the U.S. electrical power system onboard the International Space Station (ISS). The electrical power system, which is built into a 73-meter (240-foot) long solar array structure consists of solar arrays, radiators, batteries, and electronics. The entire 15.4-metric ton (17-ton) package is called the P6 Integrated Truss Segment, and is the heaviest and largest element yet delivered to the station aboard a space shuttle. The electrical system will eventually provide the power necessary for the first ISS crews to live and work in the U.S. segment.

  6. Evaluation of a Hybrid Elastic EVA Glove

    NASA Technical Reports Server (NTRS)

    Korona, F. Adam; Akin, David

    2002-01-01

    The hybrid elastic design is based upon an American Society for Engineering Education (ASEE) glove designed by at the Space Systems Laboratory (SSL) in 1985. This design uses an elastic restraint layer instead of convolute joints to achieve greater dexterity and mobility during EVA (extravehicular activity). Two pilot studies and a main study were conducted using the hybrid elastic glove and 4000-series EMU (extravehicular activity unit) glove. Data on dexterity performance, joint range of motion, grip strength and perceived exertion was assessed for the EMU and hybrid elastic gloves with correlations to a barehanded condition. During this study, 30 test subjects performed multiple test sessions using a hybrid elastic glove and a 4000- series shuttle glove in a 4.3psid pressure environment. Test results to date indicate that the hybrid elastic glove performance is approximately similar to the performance of the 4000-series glove.

  7. Dust Tolerant EVA-Compatible Connectors

    NASA Technical Reports Server (NTRS)

    Mueller, Robert P.; Townsend, Ivan I., III

    2010-01-01

    The objectives of this project are to develop connectors (quick disconnects and umbilical systems) that can be repetitively and reliably mated and de-mated during Lunar surface extra-vehicular activities. These standardized interfaces will be required for structural integrity and commodities transfer between linked surface elements. QD's fittings are needed for EVA spacesuit Primary Life Support Systems as well as liquid cooled garment circulation and suit heat rejection. Umbilical electro-mechanical systems (connectors) are needed between discrete surface systems for transfer of air, power, fluid (water), and data must be capable of being operated by extra vehicular astronaut crew members and/or robotic assistants. There exists an urgent need to prevent electro-statically charged dust and debris from clogging and degrading the interface seals and causing leakage and spills of hazardous commodities, contaminating the flowstream, and degrading the mechanisms needed for umbilical connection. Other challenges include modularity, standardization, autonomous operation, and lifetime sealing issues.

  8. Exploration Architecture Options - ECLSS, TCS, EVA Implications

    NASA Technical Reports Server (NTRS)

    Chambliss, Joe; Henninger, Don

    2011-01-01

    Many options for exploration of space have been identified and evaluated since the Vision for Space Exploration (VSE) was announced in 2004. The Augustine Commission evaluated human space flight for the Obama administration then the Human Exploration Framework Teams (HEFT and HEFT2) evaluated potential exploration missions and the infrastructure and technology needs for those missions. Lunar architectures have been identified and addressed by the Lunar Surface Systems team to establish options for how to get to, and then inhabit and explore, the moon. This paper will evaluate the options for exploration of space for the implications of architectures on the Environmental Control and Life Support (ECLSS), Thermal Control (TCS), and Extravehicular Activity (EVA) Systems.

  9. Exploration Architecture Options - ECLSS, EVA, TCS Implications

    NASA Technical Reports Server (NTRS)

    Chambliss, Joe; Henninger, Don; Lawrence, Carl

    2010-01-01

    Many options for exploration of space have been identified and evaluated since the Vision for Space Exploration (VSE) was announced in 2004. Lunar architectures have been identified and addressed in the Lunar Surface Systems team to establish options for how to get to and then inhabit and explore the moon. The Augustine Commission evaluated human space flight for the Obama administration and identified many options for how to conduct human spaceflight in the future. This paper will evaluate the options for exploration of space for the implications of architectures on the Environmental Control and Life Support (ECLSS), ExtraVehicular Activity (EVA) and Thermal Control System (TCS) Systems. The advantages and disadvantages of each architecture and options are presented.

  10. A Cabin Air Separator for EVA Oxygen

    NASA Technical Reports Server (NTRS)

    Graf, John C.

    2011-01-01

    Presently, the Extra-Vehicular Activities (EVAs) conducted from the Quest Joint Airlock on the International Space Station use high pressure, high purity oxygen that is delivered to the Space Station by the Space Shuttle. When the Space Shuttle retires, a new method of delivering high pressure, high purity oxygen to the High Pressure Gas Tanks (HPGTs) is needed. One method is to use a cabin air separator to sweep oxygen from the cabin air, generate a low pressure/high purity oxygen stream, and compress the oxygen with a multistage mechanical compressor. A main advantage to this type of system is that the existing low pressure oxygen supply infrastructure can be used as the source of cabin oxygen. ISS has two water electrolysis systems that deliver low pressure oxygen to the cabin, as well as chlorate candles and compressed gas tanks on cargo vehicles. Each of these systems can feed low pressure oxygen into the cabin, and any low pressure oxygen source can be used as an on-board source of oxygen. Three different oxygen separator systems were evaluated, and a two stage Pressure Swing Adsorption system was selected for reasons of technical maturity. Two different compressor designs were subjected to long term testing, and the compressor with better life performance and more favorable oxygen safety characteristics was selected. These technologies have been used as the basis of a design for a flight system located in Equipment Lock, and taken to Preliminary Design Review level of maturity. This paper describes the Cabin Air Separator for EVA Oxygen (CASEO) concept, describes the separator and compressor technology trades, highlights key technology risks, and describes the flight hardware concept as presented at Preliminary Design Review (PDR)

  11. EVA manipulation and assembly of space structure columns

    NASA Technical Reports Server (NTRS)

    Loughead, T. E.; Pruett, E. C.

    1980-01-01

    Assembly techniques and hardware configurations used in assembly of the basic tetrahedral cell by A7LB pressure-suited subjects in a neutral bouyancy simulator were studied. Eleven subjects participated in assembly procedures which investigated two types of structural members and two configurations of attachment hardware. The assembly was accomplished through extra-vehicular activity (EVA) only, EVA with simulated manned maneuvering unit (MMU), and EVA with simulated MMU and simulated remote manipulator system (RMS). Assembly times as low as 10.20 minutes per tetrahedron were achieved. Task element data, as well as assembly procedures, are included.

  12. Study of space shuttle EVA/IVA support requirements. Volume 2: EVA/IVA tasks, guidelines, and constraints definition

    NASA Technical Reports Server (NTRS)

    Webbon, B. W.; Copeland, R. J.; Wood, P. W., Jr.; Cox, R. L.

    1973-01-01

    The guidelines for EVA and IVA tasks to be performed on the space shuttle are defined. In deriving tasks, guidelines, and constraints, payloads were first identified from the mission model. Payload requirements, together with man and manipulator capabilities, vehicle characteristics and operation, and safety considerations led to a definition of candidate tasks. Guidelines and constraints were also established from these considerations. Scenarios were established, and screening criteria, such as commonality of EVA and IVA activities, were applied to derive representative planned and unplanned tasks. The whole spectrum of credible contingency situations with a potential requirement for EVA/IVA was analyzed.

  13. Development of an EVA systems cost model. Volume 2: Shuttle orbiter crew and equipment translation concepts and EVA workstation concept development and integration

    NASA Technical Reports Server (NTRS)

    1975-01-01

    EVA crewman/equipment translational concepts are developed for a shuttle orbiter payload application. Also considered are EVA workstation systems to meet orbiter and payload requirements for integration of workstations into candidate orbiter payload worksites.

  14. Astronaut Richard Gordon returns to hatch of spacecraft following EVA

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Astronaut Richard F. Gordon Jr., pilot for the Gemini 11 space flight, returns to the hatch of the spacecraft following extravehicular activity (EVA). This picture was taken over the Atlantic Ocean at approximately 160 nautical miles above the earth's surface.

  15. Students Speak With EVA Operations Specialist Glenda Brown

    NASA Video Gallery

    From NASA’s International Space Station Mission Control Center, EVA Operations Specialist Glenda Brown participates in a Digital Learning Network (DLN) event with students at Victory Lakes Interm...

  16. 7. LESLIE WICKMAN, EVA (EXTRA VEHICULAR ACTIVITIES) SPECIALIST, IN SPACE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. LESLIE WICKMAN, EVA (EXTRA VEHICULAR ACTIVITIES) SPECIALIST, IN SPACE SUIT AFTER TESTING IN NEUTRAL BUOYANCY TANK. AVERAGE COST OF SUIT IS $1,000,000. - Marshall Space Flight Center, Neutral Buoyancy Simulator Facility, Rideout Road, Huntsville, Madison County, AL

  17. Astronaut Dale Gardner rehearses control of MMU during EVA practice

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Astronaut Dale A. Gardner, 51-A mission specialist, rehearses control of manned maneuvering unit (MMU) during a practice for an extravehicular activity (EVA). Gardner is in the Shuttle mockup and integration laboratory at JSC.

  18. Astronauts Harris and Foale ready to egress airlock for EVA

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Astronauts Bernard A. Harris, Jr., payload commander, (top) and C. Michael Foale, mission specialist, are ready to egress airlock for an extravehicular activity (EVA) during the STS-63 mission on the Space Shuttle Discovery.

  19. EVA-glass interface bond stability

    NASA Technical Reports Server (NTRS)

    Koenig, J. L.

    1984-01-01

    The ethylene vinyl acetate/glass interface bond stability was investigated. Special methods to determine the structure of polymer/glass interface were developed. Structural changes related to hydrothermal degradation of polymer/glass interface are examined. Methods to inhibit the degradation reaction which occur at polymer/glass interface are developed.

  20. Imide/arylene ether copolymers

    NASA Technical Reports Server (NTRS)

    Jensen, Brian J. (Inventor); Hergenrother, Paul M. (Inventor); Bass, Robert G. (Inventor)

    1992-01-01

    Imide/arylene ether block copolymers are prepared by reacting anhydride terminated poly(amic acids) with amine terminated poly(arylene ethers) in polar aprotic solvents and by chemically or thermally cyclodehydrating the resulting intermediate poly(amic acids). The resulting block copolymers have one glass transition temperature or two, depending upon the particular structure and/or the compatibility of the block units. Most of these block copolymers form tough, solvent resistant films with high tensile properties.

  1. Clickable Amphiphilic Triblock Copolymers.

    PubMed

    Isaacman, Michael J; Barron, Kathryn A; Theogarajan, Luke S

    2012-06-15

    Amphiphilic polymers have recently garnered much attention due to their potential use in drug-delivery and other biomedical applications. A modular synthesis of these polymers is extremely desirable since it offers precise individual block characterization and increased yields. We present here for the first time a modular synthesis of poly(oxazoline)-poly(siloxane)-poly(oxazoline) block copolymers that have been clicked together using the copper-catalyzed azide-alkyne cycloaddition reaction. Various click methodologies for the synthesis of these polymers have been carefully evaluated and optimized. The approach using copper nanoparticles was found to be the most optimal among the methods evaluated. Furthermore, these results were extended to allow for a reactive Si-H group-based siloxane middle block to be successfully clicked. This enables the design of more complex amphiphilic block copolymers that have additional functionality, such as stimuli responsiveness, to be synthesized via a simple hydrosilylation reaction.

  2. Baroplastic Block copolymers

    NASA Astrophysics Data System (ADS)

    Hewlett, Sheldon A.

    2005-03-01

    Block copolymers with rubbery and glassy components have been observed to have pressure induced miscibility. These microphase-separated materials, termed baroplastics, were able to flow and be processed at temperatures below the Tg of the glassy component by simple compression molding and extrusion. Diblock and triblock copolymers of polystyrene and poly(butyl acrylate) or poly(2-ethyl hexyl acrylate) were synthesized by atom transfer radical polymerization (ATRP) and processed at room temperature into well defined transparent objects. SAXS and SANS measurements demonstrated partial mixing between components as a result of pressure during processing. DSC results also show the presence of distinct domains even after several processing cycles. Their mechanical properties after processing were tested and compared with commercial thermoplastic elastomers.

  3. Block copolymer battery separator

    SciTech Connect

    Wong, David; Balsara, Nitash Pervez

    2016-04-26

    The invention herein described is the use of a block copolymer/homopolymer blend for creating nanoporous materials for transport applications. Specifically, this is demonstrated by using the block copolymer poly(styrene-block-ethylene-block-styrene) (SES) and blending it with homopolymer polystyrene (PS). After blending the polymers, a film is cast, and the film is submerged in tetrahydrofuran, which removes the PS. This creates a nanoporous polymer film, whereby the holes are lined with PS. Control of morphology of the system is achieved by manipulating the amount of PS added and the relative size of the PS added. The porous nature of these films was demonstrated by measuring the ionic conductivity in a traditional battery electrolyte, 1M LiPF.sub.6 in EC/DEC (1:1 v/v) using AC impedance spectroscopy and comparing these results to commercially available battery separators.

  4. EVA Robotic Assistant Project: Platform Attitude Prediction

    NASA Technical Reports Server (NTRS)

    Nickels, Kevin M.

    2003-01-01

    The Robotic Systems Technology Branch is currently working on the development of an EVA Robotic Assistant under the sponsorship of the Surface Systems Thrust of the NASA Cross Enterprise Technology Development Program (CETDP). This will be a mobile robot that can follow a field geologist during planetary surface exploration, carry his tools and the samples that he collects, and provide video coverage of his activity. Prior experiments have shown that for such a robot to be useful it must be able to follow the geologist at walking speed over any terrain of interest. Geologically interesting terrain tends to be rough rather than smooth. The commercial mobile robot that was recently purchased as an initial testbed for the EVA Robotic Assistant Project, an ATRV Jr., is capable of faster than walking speed outside but it has no suspension. Its wheels with inflated rubber tires are attached to axles that are connected directly to the robot body. Any angular motion of the robot produced by driving over rough terrain will directly affect the pointing of the on-board stereo cameras. The resulting image motion is expected to make tracking of the geologist more difficult. This will either require the tracker to search a larger part of the image to find the target from frame to frame or to search mechanically in pan and tilt whenever the image motion is large enough to put the target outside the image in the next frame. This project consists of the design and implementation of a Kalman filter that combines the output of the angular rate sensors and linear accelerometers on the robot to estimate the motion of the robot base. The motion of the stereo camera pair mounted on the robot that results from this motion as the robot drives over rough terrain is then straightforward to compute. The estimates may then be used, for example, to command the robot s on-board pan-tilt unit to compensate for the camera motion induced by the base movement. This has been accomplished in two ways

  5. Planetary Protection Considerations in EVA System Design

    NASA Technical Reports Server (NTRS)

    Eppler, Dean B.; Kosmo, Joseph J.

    2011-01-01

    very little expression of these anomalies. hardware from the human-occupied area may limit (although not likely eliminate) external materials in the human habitat. Definition of design-to requirements is critical to understanding technical feasibility and costs. The definition of Planetary Protection needs in relation to EVA mission and system element development cost impacts should be considered and interpreted in terms of Plausible Protection criteria. Since EVA operations will have the most direct physical interaction with the Martian surface, PP needs should be considered in the terms of mitigating hardware and operations impacts and costs.

  6. Imide/Arylene Ether Copolymers

    NASA Technical Reports Server (NTRS)

    Jensen, Brian J.; Hergenrother, Paul M.; Bass, Robert G.

    1991-01-01

    New imide/arylene ether copolymers prepared by reacting anhydride-terminated poly(amic acids) with amine-terminated poly(arylene ethers) in polar aprotic solvents. Each resulting copolymer may have one glass-transition temperature or two, depending on chemical structure and/or compatibility of block units. Most of copolymers form tough, solvent-resistant films with high tensile properties. Films cast from solution tough and flexible, and exhibit useful thermal and mechanical properties. Potentially useful as moldings, adhesives, or composite matrices. Because of flexible arylene ether blocks, these copolymers easier to process than polyimides.

  7. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) co-polymer production from a local isolate, Brevibacillus invocatus MTCC 9039.

    PubMed

    Sankhla, Indu Singh; Bhati, Ranjana; Singh, Akhilesh Kumar; Mallick, Nirupama

    2010-03-01

    Accumulation of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] co-polymer by a local isolate, Brevibacillus invocatus MTCC 9039 under batch mode was investigated under glucose, acetate and propionate-supplemented conditions. Cells harvested at the stationary phase of growth depicted maximum accumulation of poly-3-hydroxybutyrate (PHB), i.e. 3% of dry cell weight (dcw) at pH 7.0 and temperature 30 degrees C at 48h of incubation. PHB accumulation reached up to 52% (dcw) under 3% glucose with 1% acetate supplementation. P(3HB-co-3HV) co-polymer synthesis was observed under propionate-supplemented condition, which reached up to 45% under 3% glucose with 1% propionate supplementation. Optimization of process parameters by response surface methodology (RSM) resulted into co-polymer accumulation up to 65% (dcw) at 2.08% glucose, 1.62% acetate, 0.75% propionate and 2.15 g l(-1) KH(2)PO(4) concentrations. This co-polymer exhibited comparable material properties with the commercial [P(3HB-co-3HV)] co-polymers, whereas the elasticity was tremendously high and could be comparable with polypropylene. Thus, B. invocatus MTCC 9039 is emerging as an interesting organism and could be exploited further for P(3HB-co-3HV) co-polymer production.

  8. The influence of Ca-Mg-Al hydrotalcite synthesized from brine water on thermal and mechanical properties of HTlc-EVA composite

    SciTech Connect

    Karina, Wiwiek Heraldy, Eddy Pramono, Edi; Heriyanto,; Astuti, Shanti

    2016-02-08

    Ca-Mg-Al hydrotalcite-like compound (Ca-Mg-Al HTlc) was prepared by co-precipitation method using brine water that is well known as the desalination process waste water. The structure of Ca-Mg-Al HTlc was determined by X-Ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) analysis. Ca-Mg-Al HTlc was studied as a non-halogenated filler in ethylene vinyl acetate (EVA) matrix. Composites with different filler concentrations were prepared to evaluate the influence of Ca-Mg-Al HTlc on thermal and mechanical properties of EVA.The presence of Ca-Mg-Al HTlc in the composite has been confirmed by FTIR analysis. Thermal properties of composites show significant reduction of degradation temperature as well as the loading of HTlc in EVA. However, the total enthalpies combustion of composites with 1% and 5% HTlc loadings higher compared to neat EVA. Further, mechanical properties were determined by tensile test. The result shows that tensile strength and elongation at break of composites decrease relatively by Ca-Mg-Al HTlc addition.

  9. The influence of Ca-Mg-Al hydrotalcite synthesized from brine water on thermal and mechanical properties of HTlc-EVA composite

    NASA Astrophysics Data System (ADS)

    Karina, Wiwiek; Heraldy, Eddy; Pramono, Edi; Heriyanto, Astuti, Shanti

    2016-02-01

    Ca-Mg-Al hydrotalcite-like compound (Ca-Mg-Al HTlc) was prepared by co-precipitation method using brine water that is well known as the desalination process waste water. The structure of Ca-Mg-Al HTlc was determined by X-Ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) analysis. Ca-Mg-Al HTlc was studied as a non-halogenated filler in ethylene vinyl acetate (EVA) matrix. Composites with different filler concentrations were prepared to evaluate the influence of Ca-Mg-Al HTlc on thermal and mechanical properties of EVA.The presence of Ca-Mg-Al HTlc in the composite has been confirmed by FTIR analysis. Thermal properties of composites show significant reduction of degradation temperature as well as the loading of HTlc in EVA. However, the total enthalpies combustion of composites with 1% and 5% HTlc loadings higher compared to neat EVA. Further, mechanical properties were determined by tensile test. The result shows that tensile strength and elongation at break of composites decrease relatively by Ca-Mg-Al HTlc addition.

  10. Expedition 16 Flight Engineer Tani Performs EVA

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Astronaut Daniel Tani (top center), Expedition 16 flight engineer, participates in the second of five scheduled sessions of extravehicular activity (EVA) as construction continues on the International Space Station (ISS). During the 6-hour and 33-minute space walk, Tani and STS-120 mission specialist Scott Parazynski (out of frame), worked in tandem to disconnect cables from the P6 truss, allowing it to be removed from the Z1 truss. Tani also visually inspected the station's starboard Solar Alpha Rotary Joint (SARJ) and gathered samples of 'shavings' he found under the joint's multilayer insulation covers. The space walkers also outfitted the Harmony module, mated the power and data grapple fixture and reconfigured connectors on the starboard 1 (S1) truss that will allow the radiator on S1 to be deployed from the ground later. The moon is visible at lower center. The STS-120 mission launched from Kennedy Space Center's launch pad 39A at 11:38:19 a.m. (EDT) on October 23, 2007.

  11. Astronaut Sellers Performs STS-112 EVA

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Launched October 7, 2002 aboard the Space Shuttle Orbiter Atlantis, the STS-112 mission lasted 11 days and performed three sessions of Extra Vehicular Activity (EVA). Its primary mission was to install the Starboard Side Integrated Truss Structure (S1) and Equipment Translation Aid (CETA) Cart to the International Space Station (ISS). The S1 truss provides structural support for the orbiting research facility's radiator panels, which use ammonia to cool the Station's complex power system. The S1 truss, attached to the S0 (S Zero) truss installed by the previous STS-110 mission, flows 637 pounds of anhydrous ammonia through three heat rejection radiators. The truss is 45-feet long, 15-feet wide, 10-feet tall, and weighs approximately 32,000 pounds. The CETA is the first of two human-powered carts that will ride along the International Space Station's railway providing a mobile work platform for future extravehicular activities by astronauts. In this photograph, Astronaut Piers J. Sellers uses both a handrail on the Destiny Laboratory and a foot restraint on the Space Station Remote Manipulator System or Canadarm2 to remain stationary while performing work at the end of the STS-112 mission's second space walk. A cloud-covered Earth provides the backdrop for the scene.

  12. Anti-plasticizing effect of amorphous indomethacin induced by specific intermolecular interactions with PVA copolymer.

    PubMed

    Ueda, Hiroshi; Aikawa, Shohei; Kashima, Yousuke; Kikuchi, Junko; Ida, Yasuo; Tanino, Tadatsugu; Kadota, Kazunori; Tozuka, Yuichi

    2014-09-01

    The mechanism of how poly(vinyl alcohol-co-acrylic acid-co-methyl methacrylate) (PVA copolymer) stabilizes an amorphous drug was investigated. Solid dispersions of PVA copolymer, poly(vinyl pyrrolidone) (PVP), and poly(vinyl pyrrolidone-co-vinyl acetate) (PVPVA) with indomethacin (IMC) were prepared. The glass transition temperature (Tg)-proportion profiles were evaluated by differential scanning calorimetry (DSC). General Tg profiles decreasing with the IMC ratio were observed for IMC-PVP and IMC-PVPVA samples. An interesting antiplasticizing effect of IMC on PVA copolymer was observed; Tg increased up to 20% IMC ratio. Further addition of IMC caused moderate reduction with positive deviation from theoretical values. Specific hydrophilic and hydrophobic interactions between IMC and PVA copolymer were revealed by infrared spectra. The indole amide of IMC played an important role in hydrogen bonding with PVA copolymer, but not with PVP and PVPVA. X-ray diffraction findings and the endotherm on DSC profiles suggested that PVA copolymer could form a semicrystalline structure and a possibility of correlation of the crystallographic nature with its low hygroscopicity was suggested. PVA copolymer was able to prevent crystallization of amorphous IMC through both low hygroscopicity and the formation of a specific intermolecular interaction compared with that with PVP and PVPVA.

  13. Surface functionalization of carbon nanotubes by direct encapsulation with varying dosages of amphiphilic block copolymers

    NASA Astrophysics Data System (ADS)

    Yao, Xueping; Li, Jie; Kong, Liang; Wang, Yong

    2015-08-01

    Encapsulation of carbon nanotubes (CNTs) by amphiphilic block copolymers is an efficient way to stabilize CNTs in solvents. However, the appropriate dosages of copolymers and the assembled structures are difficult to predict and control because of the insufficient understanding on the encapsulation process. We encapsulate multiwalled CNTs with polystyrene-block-poly (4-vinyl pyridine) (PS-b-P4VP) by directly mixing them in acetic acid under sonication. The copolymer forms a lamellar structure along the surface of CNTs with the PS blocks anchoring on the tube wall and the P4VP blocks exposed to the outside. The encapsulated CNTs achieve good dispersibility in polar solvents over long periods. To increase our understanding of the encapsulation process we investigate the assembled structures and stability of copolymer/CNTs mixtures with changing mass ratios. Stable dispersions are obtained at high mass ratios between the copolymer and CNTs, i.e. 2 or 3, with the presence of free spherical micelles. Transmission electron microscopy and thermal gravimetric analysis determine that the threshold for the complete coverage of CNTs by the copolymer occurs at the mass ratio of 1.5. The coated copolymer layer activates the surface of CNTs, enabling further functionalization of CNTs. For instance, atomic layer deposition of TiO2 produces conformal thin layers on the encapsulated CNTs while isolated TiO2 bumps are produced on the pristine, inert CNTs.

  14. Preparation of vinyl acetate

    DOEpatents

    Tustin, Gerald Charles; Zoeller, Joseph Robert; Depew, Leslie Sharon

    1998-01-01

    This invention pertains to the preparation of vinyl acetate by contacting a mixture of hydrogen and ketene with a heterogeneous catalyst containing a transition metal to produce acetaldehyde, which is then reacted with ketene in the presence of an acid catalyst to produce vinyl acetate.

  15. Preparation of vinyl acetate

    DOEpatents

    Tustin, G.C.; Zoeller, J.R.; Depew, L.S.

    1998-03-24

    This invention pertains to the preparation of vinyl acetate by contacting a mixture of hydrogen and ketene with a heterogeneous catalyst containing a transition metal to produce acetaldehyde, which is then reacted with ketene in the presence of an acid catalyst to produce vinyl acetate.

  16. Interfacial Modification by Copolymers: The Importance of Copolymer Microstructure

    NASA Astrophysics Data System (ADS)

    Dadmun, Mark; Eastwood, Eric

    2002-03-01

    The dispersion of nanoscale particles or domains in a polymer matrix can readily lead to nonlinear enhancement of material properties. Our research group has been examining two primary methods to improve the properties of multicomponent polymer systems: compatibilization of a blend with an interfacial modifier or improving the miscibility and properties of polymer blends with specific interactions. In this talk, the importance of specific copolymer microstructure on its ability to strengthen a biphasic interface will be discussed. Atom transfer radical polymerization has been utilized to polymerize a series of multiblock copolymers containing styrene and methyl methacrylate. This, in turn, has allowed the synthesis of a series of copolymers with careful control of the sequence distribution. Subsequent experiments that determine the interfacial strength between two polymers in the presence and absence of these copolymers has provided critical information that documents the importance of copolymer sequence distribution on its ability to strengthen a biphasic interface.

  17. A Human Factors Analysis of EVA Time Requirements

    NASA Technical Reports Server (NTRS)

    Pate, Dennis W.

    1997-01-01

    Human Factors Engineering (HFE) is a discipline whose goal is to engineer a safer, more efficient interface between humans and machines. HFE makes use of a wide range of tools and techniques to fulfill this goal. One of these tools is known as motion and time study, a technique used to develop time standards for given tasks. During the summer of 1995, a human factors motion and time study was initiated with the goals of developing a database of EVA task times and developing a method of utilizing the database to predict how long an EVA should take. Initial development relied on the EVA activities performed during the STS-61 (Hubble) mission. The first step of the study was to become familiar with EVA's, the previous task-time studies, and documents produced on EVA's. After reviewing these documents, an initial set of task primitives and task-time modifiers was developed. Data was collected from videotaped footage of two entire STS-61 EVA missions and portions of several others, each with two EVA astronauts. Feedback from the analysis of the data was used to further refine the primitives and modifiers used. The project was continued during the summer of 1996, during which data on human errors was also collected and analyzed. Additional data from the STS-71 mission was also collected. Analysis of variance techniques for categorical data was used to determine which factors may affect the primitive times and how much of an effect they have. Probability distributions for the various task were also generated. Further analysis of the modifiers and interactions is planned.

  18. Minimizing EVA Airlock Time and Depress Gas Losses

    NASA Technical Reports Server (NTRS)

    Trevino, Luis A.; Lafuse, Sharon A.

    2008-01-01

    This paper describes the need and solution for minimizing EVA airlock time and depress gas losses using a new method that minimizes EVA out-the-door time for a suited astronaut and reclaims most of the airlock depress gas. This method consists of one or more related concepts that use an evacuated reservoir tank to store and reclaim the airlock depress gas. The evacuated tank can be an inflatable tank, a spent fuel tank from a lunar lander descent stage, or a backup airlock. During EVA airlock operations, the airlock and reservoir would be equalized at some low pressure, and through proper selection of reservoir size, most of the depress gas would be stored in the reservoir for later reclamation. The benefit of this method is directly applicable to long duration lunar and Mars missions that require multiple EVA missions (up to 100, two-person lunar EVAs) and conservation of consumables, including depress pump power and depress gas. The current ISS airlock gas reclamation method requires approximately 45 minutes of the astronaut s time in the airlock and 1 KW in electrical power. The proposed method would decrease the astronaut s time in the airlock because the depress gas is being temporarily stored in a reservoir tank for later recovery. Once the EVA crew is conducting the EVA, the volume in the reservoir would be pumped back to the cabin at a slow rate. Various trades were conducted to optimize this method, which include time to equalize the airlock with the evacuated reservoir versus reservoir size, pump power to reclaim depress gas versus time allotted, inflatable reservoir pros and cons (weight, volume, complexity), and feasibility of spent lunar nitrogen and oxygen tanks as reservoirs.

  19. Cooperative EVA/Telerobotic Surface Operations in Support of Exploration Science

    NASA Astrophysics Data System (ADS)

    Akin, David L.

    2001-01-01

    The contents include: 1) Planetary Surface Robotics; 2) EVA Difficulties from Apollo; 3) Robotic Capabilities for EVA Support; 4) Astronaut Support Vehicle; 5) Three ASV Preliminary Designs; 6) Small Single-arm Assistant; 7) Dual-arm Assistant; 8) Large EVA Assistant; 9) Lessons Learned-Preliminary Designs; 10) Rover Design Assumptions; 11) Design Requirements-Terrain; 12) Design Requirements; 13) Science Payload; 14) Manipulator Arm; 15) EVA Multiple Robot Cooperation; 16) SSL Rover Body Concept; 17) Advanced EVA Support Rover Concept; 18) Robotic Access to Restricted Sites; 19) Robotic Rescue of EVA crew; and 19) Why Do We Need Humans? This paper is presented in viewgraph form.

  20. Polyether/Polyester Graft Copolymers

    NASA Technical Reports Server (NTRS)

    Bell, Vernon L., Jr.; Wakelyn, N.; Stoakley, D. M.; Proctor, K. M.

    1986-01-01

    Higher solvent resistance achieved along with lower melting temperature. New technique provides method of preparing copolymers with polypivalolactone segments grafted onto poly (2,6-dimethyl-phenylene oxide) backbone. Process makes strong materials with improved solvent resistance and crystalline, thermally-reversible crosslinks. Resulting graft copolymers easier to fabricate into useful articles, including thin films, sheets, fibers, foams, laminates, and moldings.

  1. Nanofabrication in cellulose acetate.

    PubMed

    Zeng, Hongjun; Lajos, Robert; Metlushko, Vitali; Elzy, Ed; An, Se Young; Sautner, Joshua

    2009-03-07

    We have demonstrated nanofabrication with commercialized cellulose acetate. Cellulose acetate is used for bulk nanofabrication and surface nanofabrication. In bulk nanofabrication, cellulose acetate reacts with an e-beam and permanent patterns are formed in it instead of being transferred to other substrates. We have studied the nano relief modulation performance of cellulose acetate before and after development. The depth of the nanopatterns is magnified after development, and is varied by exposing dosage and line width of the pattern. The thinnest 65 nm wide line is achieved in the bulk fabrication. We also demonstrate a binary phase Fresnel lens array which is directly patterned in a cellulose acetate sheet. Because of its unique mechanical and optical properties, cellulose is a good candidate for a template material for soft imprinting lithography. In the surface nanofabrication, cellulose acetate thin film spin-coated on silicon wafers is employed as a new resist for e-beam lithography. We achieved 50 nm lines with 100 nm pitches, dots 50 nm in diameter, and single lines with the smallest width of 20 nm. As a new resist of e-beam lithography, cellulose acetate has high resolution comparable with conventional resists, while having several advantages such as low cost, long stock time and less harmfulness to human health.

  2. EVA tools and equipment reference book

    NASA Technical Reports Server (NTRS)

    Fullerton, R. K.

    1993-01-01

    This document contains a mixture of tools and equipment used throughout the space shuttle-based extravehicular activity (EVA) program. Promising items which have reached the prototype stage of development are also included, but should not be considered certified ready for flight. Each item is described with a photo, a written discussion, technical specifications, dimensional drawings, and points of contact for additional information. Numbers on the upper left-hand corner of each photo may be used to order specific pictures from NASA and contractor photo libraries. Points of contact were classified as either operational or technical. An operational contact is an engineer from JSC Mission Operations Directorate who is familiar with the basic function and on-orbit use of the tool. A technical contact would be the best source of detailed technical specifications and is typically the NASA subsystem manager. The technical information table for each item uses the following terms to describe the availability or status of each hardware item: Standard - Flown on every mission as standard manifest; Flight specific - Potentially available for flight, not flown every mission (flight certification cannot be guaranteed and recertification may be required); Reference only - Item no longer in active inventory or not recommended for future use, some items may be too application-specific for general use; and Developmental - In the prototype stage only and not yet available for flight. The current availability and certification of any flight-specific tool should be verified with the technical point of contact. Those tools built and fit checked for Hubble Space Telescope maintenance are program dedicated and are not available to other customers. Other customers may have identical tools built from the existing, already certified designs as an optional service.

  3. EVA Glove Sensor Feasbility II Abstract

    NASA Technical Reports Server (NTRS)

    Melone, Kate

    2014-01-01

    The main objectives for the glove project include taking various measurements from human subjects during and after they perform different tasks in the glove box, acquiring data from these tests and determining the accuracy of these results, interpreting and analyzing this data, and using the data to better understand how hand injuries are caused during EVAs.1 Some of these measurements include force readings, temperature readings, and micro-circulatory blood flow.1 The three glove conditions tested were ungloved (a comfort glove was worn to house the sensors), Series 4000, and Phase VI. The general approach/procedure for the glove sensor feasibility project is as follows: 1. Prepare test subject for testing. This includes attaching numerous sensors (approximately 50) to the test subject, wiring, and weaving the sensors and wires in the glove which helps to keep everything together. This also includes recording baseline moisture data using the Vapometer and MoistSense. 2. Pressurizing the glove box. Once the glove box is pressurized to the desired pressure (4.3 psid), testing can begin. 3. Testing. The test subject will perform a series of tests, some of which include pinching a load cell, making a fist, pushing down on a force plate, and picking up metal pegs, rotating them 90 degrees, and placing them back in the peg board. 4. Post glove box testing data collection. After the data is collected from inside the glove box, the Vapometer and MoistSense device will be used to collect moisture data from the subject's hand. 5. Survey. At the conclusion of testing, he/she will complete a survey that asks questions pertaining to comfort/discomfort levels of the glove, glove sizing, as well as offering any additional feedback.

  4. Water Pump Development for the EVA PLSS

    NASA Technical Reports Server (NTRS)

    Schuller, Michael; Kurwitz, Cable; Goldman, Jeff; Morris, Kim; Trevino, Luis

    2009-01-01

    This paper describes the effort by the Texas Engineering Experiment Station (TEES) and Honeywell for NASA to design, fabricate, and test a preflight prototype pump for use in the Extravehicular activity (EVA) portable life support subsystem (PLSS). Major design decisions were driven by the need to reduce the pump s mass, power, and volume compared to the existing PLSS pump. In addition, the pump will accommodate a much wider range of abnormal conditions than the existing pump, including vapor/gas bubbles and increased pressure drop when employed to cool two suits simultaneously. A positive displacement, external gear type pump was selected because it offers the most compact and highest efficiency solution over the required range of flow rates and pressure drops. An additional benefit of selecting a gear pump design is that it is self priming and capable of ingesting noncondensable gas without becoming "air locked." The chosen pump design consists of a 28 V DC, brushless, sealless, permanent magnet motor driven, external gear pump that utilizes a Honeywell development that eliminates the need for magnetic coupling. Although the planned flight unit will use a sensorless motor with custom designed controller, the preflight prototype to be provided for this project incorporates Hall effect sensors, allowing an interface with a readily available commercial motor controller. This design approach reduced the cost of this project and gives NASA more flexibility in future PLSS laboratory testing. The pump design was based on existing Honeywell designs, but incorporated features specifically for the PLSS application, including all of the key features of the flight pump. Testing at TEES will simulate the vacuum environment in which the flight pump will operate. Testing will verify that the pump meets design requirements for range of flow rates, pressure rise, power consumption, working fluid temperature, operating time, and restart capability. Pump testing is currently

  5. Russian-American Cooperation in EVA Area (from Russian Perspective)

    NASA Astrophysics Data System (ADS)

    Tsygankov, O. S.; Alexandrov, A. P.; Poleschuk, A. F.

    Russian and American extravehicular activity (EVA) specialists started cooperation after Russia entered the ISS Program. Practical work began in the framework of the Mir-NASA Program, when astronauts J. Linenger, M. Foale and D. Wolf were trained in Russia and participated in the EVA on MIR. This was the intercourse of two experiences, two equal schools each formed under specific conditions. The Report studies the peculiarities of national EVA schools, shows the experience in their integration for the ISS purposes. Organizational aspects of the ISS Program to optimize the implementation of the EVA tasks are presented. It gives examples of the cooperation and development of the hardware equally compatible both with EMU and ORLAN-M space suits, impacts of different schools on the operational methods. It presents proposals on the further integration of the Russian and American schools, considers the prerequisites and perspectives of maximally integrated EVA system for the ISS and the possibility of its incorporation in future in to the mission to Mars.

  6. Effects of EVA spacesuit glove on grasping and pinching tasks

    NASA Astrophysics Data System (ADS)

    Appendino, Silvia; Battezzato, Alessandro; Chen Chen, Fai; Favetto, Alain; Mousavi, Mehdi; Pescarmona, Francesco

    2014-03-01

    The human hand has a wide range of degrees of freedom, allowing a great variety of movements, and is also one of the most sensitive parts of the human body. Due to these characteristics, it is the most important tool for astronauts to perform extravehicular activities (EVA). However, astronauts must wear mandatory EVA equipment to be protected from the harsh conditions in space and this strongly reduces hand performance, in particular as regards dexterity, tactile perception, mobility and fatigue. Several studies have been conducted to determine the influence of the EVA glove on manual capabilities, both in the past and more recently. This study presents experimental data regarding the performance decline occurring in terms of force and fatigue in the execution of grasping and pinching tasks when wearing an EVA glove, in pressurized and unpressurized conditions, compared with barehanded potential. Results show that wearing the unpressurized EVA glove hinders grip and lateral pinch performances, dropping exerted forces to about 50-70%, while it barely affects two- and three-finger pinch performances. On the other hand, wearing the pressurized glove worsens performances in all cases, reducing forces to about 10-30% of barehanded potential. The results are presented and compared with the previous literature.

  7. Enhanced Controlled Transdermal Delivery of Mexazolam Using Ethylene-vinyl Acetate

    PubMed Central

    Weon Cho, Cheong; Chul Shin, Sang

    2012-01-01

    Repeated oral administration of mexazolam, an anti-anxiety agent, may cause adverse effects such as gastric disturbance, drowsiness, and ataxia due to transiently high blood levels. Transdermal administration would avoid the systemic side effects and gastric disorders after oral administration. We have developed a matrix using ethylene-vinyl acetate (EVA), a heat-processible and flexible material, for transdermal delivery of mexazolam. Drug solubility was highest at 40% PEG-400 volume fraction. The release and permeation profiles through the rat skin were determined for 24 h using a modified Keshary-Chien diffusion cell. The drug release was increased by increasing the concentration with a linear relationship between the release rate and the square root of loading dose. Increasing temperature increased drug release from the EVA matrix. The activation energy (Ea), which was measured from a slope of log P versus 1000/T plot, was 8.64 Kcal/mol for a 1.5% loading dose. To reduce the brittleness and increase the pore of the EVA matrix, diffrent plasticizers were used. Among the plasticizers, including the citrates or the phthalate groups, diethyl phthalate showed the highest effect on the release of mexazolam. To increase the skin permeation of mexazolam from the EVA matrix, enhancers such as the fatty acids, the pyrrolidones, the propylene glycol derivatives, the glycerides, and the non-ionic surfactants were added to the EVA matrix, respectively, and skin permeation was evaluated using a modified Keshary-Chien diffusion cell fitted with intact excised rat skin. Among the several enhancers used, N-methyl-2-pyrrolidone showed the best enhancement factor. In conclusion, enhanced transdermal delivery of mexazolam through an EVA matrix containing plasticizer and a permeation enhancer could be useful in the development of a transdermal drug delivery system. PMID:25317180

  8. Development of a pH sensor based on a nanostructured filter adding pH-sensitive fluorescent dye for detecting acetic acid in photovoltaic modules

    NASA Astrophysics Data System (ADS)

    Asaka, Takashi; Itayama, Tomohiro; Nagasaki, Hideaki; Iwami, Kentaro; Yamamoto, Chizuko; Hara, Yukiko; Masuda, Atsushi; Umeda, Norihiro

    2015-08-01

    Acetic acid formed via the hydrolysis of ethylene vinyl acetate (EVA) as an encapsulant in photovoltaic (PV) modules causes a decrease in the conversion efficiency of such modules by grid corrosion. Here, a nondestructive and simple optical method for evaluating the condition of PV modules is proposed. This method uses a dual-wavelength pH-sensitive fluorescent dye to detect acetic acid in PV modules using a change in pH. The change in pH induced by the formation of acetic acid is detected by the change in the ratio of the fluorescent intensities of two peaks of the dye. A pH-sensitive fluorescent dye showed sensitivity for small amounts of acetic acid such as that produced from EVA. Furthermore, a membrane filter dyed with a pH-sensitive fluorescent dye was confirmed to detect acetic acid in aged EVA after a damp-heat test (85 °C, 85%) for 5000 h in PV modules.

  9. STS-33 EVA Prep and Post with Gregory, Blaha, Carter, Thorton, and Musgrave in FFT

    NASA Technical Reports Server (NTRS)

    1989-01-01

    This video shows the crew in the airlock of the FFT, talking with technicians about the extravehicular activity (EVA) equipment. Thornton and Carter put on EVA suits and enter the airlock as the other crew members help with checklists.

  10. Mission Specialists Mario Runco and Greg Harbaugh suiting up for EVA.

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Candid view of EVA Mission Specialists Mario Runco and Greg Harbaugh suiting up for EVA in the middeck with the assistance of Mission Specialist Susan Helms (reviewing the operation with a procedural checklist).

  11. STS-64 Mission Onboard Photograph - Extravehicular Activity (EVA)

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Astronaut Mark Lee (red stripe on extravehicular activity suit) tests the new backpack called Simplified Aid for EVA Rescue (SAFER), a system designed for use in the event a crew member becomes untethered while conducting an EVA. The Lidar-In-Space Technology Experiment (LITE) is shown in the foreground. The LITE payload employs lidar, which stands for light detection and ranging, a type of optical radar using laser pulses instead of radio waves to study Earth's atmosphere. Unprecedented views were obtained of cloud structures, storm systems, dust clouds, pollutants, forest burning, and surface reflectance. The STS-64 mission marked the first untethered U.S. EVA in 10 years, and was launched on September 9, 1994, aboard the Space Shuttle Orbiter Discovery.

  12. Enhanced transdermal delivery of loratadine from the EVA matrix.

    PubMed

    Cho, Cheong-Weon; Choi, Jun-Shik; Kim, Seong-Jin; Shin, Sang-Chul

    2009-05-01

    Various enhancers, such as fatty acids (saturated, unsaturated), glycerides, propylene glycols, and non-ionic surfactants, have been incorporated in the loratadine-EVA matrix to increase the rate of skin permeation of loratadine from an EVA matrix. The enhancing effects of these enhancers on the skin permeation of loratadine were evaluated using a modified Keshary-Chien cell fitted with intact excised rat skin. The penetration enhancers showed a higher flux, probably due to the enhancing effect on the skin barrier, the stratum corneum. Among the enhancers used, such as the fatty acids, glycols, propylene glycols, and non-ionic surfactants, linoleic acid showed the best enhancement. For the enhanced transdermal delivery of loratadine, application of an EVA matrix containing a permeation enhancer might be useful in the development of a transdermal drug delivery system.

  13. Acid-Labile Amphiphilic PEO-b-PPO-b-PEO Copolymers: Degradable Poloxamer Analogs.

    PubMed

    Worm, Matthias; Kang, Biao; Dingels, Carsten; Wurm, Frederik R; Frey, Holger

    2016-05-01

    Poly ((ethylene oxide)-b-(propylene oxide)-b-(ethylene oxide)) triblock copolymers commonly known as poloxamers or Pluronics constitute an important class of nonionic, biocompatible surfactants. Here, a method is reported to incorporate two acid-labile acetal moieties in the backbone of poloxamers to generate acid-cleavable nonionic surfactants. Poly(propylene oxide) is functionalized by means of an acetate-protected vinyl ether to introduce acetal units. Three cleavable PEO-PPO-PEO triblock copolymers (Mn,total = 6600, 8000, 9150 g·mol(-1) ; Mn,PEO = 2200, 3600, 4750 g·mol(-1) ) have been synthesized using anionic ring-opening polymerization. The amphiphilic copolymers exhibit narrow molecular weight distributions (Ð = 1.06-1.08). Surface tension measurements reveal surface-active behavior in aqueous solution comparable to established noncleavable poloxamers. Complete hydrolysis of the labile junctions after acidic treatment is verified by size exclusion chromatography. The block copolymers have been employed as surfactants in a miniemulsion polymerization to generate polystyrene (PS) nanoparticles with mean diameters of ≈200 nm and narrow size distribution, as determined by dynamic light scattering and scanning electron microscopy. Acid-triggered precipitation facilitates removal of surfactant fragments from the nanoparticles, which simplifies purification and enables nanoparticle precipitation "on demand."

  14. Shoulder Injuries in US Astronauts Related to EVA Suit Design

    NASA Technical Reports Server (NTRS)

    Scheuring, R. A.; McCulloch, P.; Van Baalen, Mary; Minard, Charles; Watson, Richard; Blatt, T.

    2011-01-01

    Introduction: For every one hour spent performing extravehicular activity (EVA) in space, astronauts in the US space program spend approximately six to ten hours training in the EVA spacesuit at NASA-Johnson Space Center's Neutral Buoyancy Lab (NBL). In 1997, NASA introduced the planar hard upper torso (HUT) EVA spacesuit which subsequently replaced the existing pivoted HUT. An extra joint in the pivoted shoulder allows increased mobility but also increased complexity. Over the next decade a number of astronauts developed shoulder problems requiring surgical intervention, many of whom performed EVA training in the NBL. This study investigated whether changing HUT designs led to shoulder injuries requiring surgical repair. Methods: US astronaut EVA training data and spacesuit design employed were analyzed from the NBL data. Shoulder surgery data was acquired from the medical record database, and causal mechanisms were obtained from personal interviews Analysis of the individual HUT designs was performed as it related to normal shoulder biomechanics. Results: To date, 23 US astronauts have required 25 shoulder surgeries. Approximately 48% (11/23) directly attributed their injury to training in the planar HUT, whereas none attributed their injury to training in the pivoted HUT. The planar HUT design limits shoulder abduction to 90 degrees compared to approximately 120 degrees in the pivoted HUT. The planar HUT also forces the shoulder into a forward flexed position requiring active retraction and extension to increase abduction beyond 90 degrees. Discussion: Multiple factors are associated with mechanisms leading to shoulder injury requiring surgical repair. Limitations to normal shoulder mechanics, suit fit, donning/doffing, body position, pre-existing injury, tool weight and configuration, age, in-suit activity, and HUT design have all been identified as potential sources of injury. Conclusion: Crewmembers with pre-existing or current shoulder injuries or certain

  15. Crosscutting Development- EVA Tools and Geology Sample Acquisition

    NASA Technical Reports Server (NTRS)

    2011-01-01

    Exploration to all destinations has at one time or another involved the acquisition and return of samples and context data. Gathered at the summit of the highest mountain, the floor of the deepest sea, or the ice of a polar surface, samples and their value (both scientific and symbolic) have been a mainstay of Earthly exploration. In manned spaceflight exploration, the gathering of samples and their contextual information has continued. With the extension of collecting activities to spaceflight destinations comes the need for geology tools and equipment uniquely designed for use by suited crew members in radically different environments from conventional field geology. Beginning with the first Apollo Lunar Surface Extravehicular Activity (EVA), EVA Geology Tools were successfully used to enable the exploration and scientific sample gathering objectives of the lunar crew members. These early designs were a step in the evolution of Field Geology equipment, and the evolution continues today. Contemporary efforts seek to build upon and extend the knowledge gained in not only the Apollo program but a wealth of terrestrial field geology methods and hardware that have continued to evolve since the last lunar surface EVA. This paper is presented with intentional focus on documenting the continuing evolution and growing body of knowledge for both engineering and science team members seeking to further the development of EVA Geology. Recent engineering development and field testing efforts of EVA Geology equipment for surface EVA applications are presented, including the 2010 Desert Research and Technology Studies (Desert RATs) field trial. An executive summary of findings will also be presented, detailing efforts recommended for exotic sample acquisition and pre-return curation development regardless of planetary or microgravity destination.

  16. An EVA Suit Fatigue, Strength, and Reach Model

    NASA Technical Reports Server (NTRS)

    Maida, James C.

    1999-01-01

    The number of Extra-Vehicular Activities (EVAs) performed will increase dramatically with the upcoming Space Station assembly missions. It is estimated that up to 900 EVA hours may be required to assemble the Space Station with an additional 200 hours per year for maintenance requirements. Efficient modeling tools will be essential to assist in planning these EVAS. Important components include strength and fatigue parameters, multi-body dynamics and kinematics. This project is focused on building a model of the EVA crew member encompassing all these capabilities. Phase 1, which is currently underway, involves collecting EMU suited and unsuited fatigue, strength and range of motion data, for all major joints of the body. Phase 2 involves processing the data for model input, formulating comparisons between the EMU suits and deriving generalized relationships between suited and unsuited data. Phase 3 will be formulation of a multi-body dynamics model of the EMU capable of predicting mass handling properties and integration of empirical data into the model. Phase 4 will be validation of the model with collected EMU data from the Neutral Buoyancy Laboratory at NASA/JSC. Engineers and designers will use tie EVA suit database to better understand the capabilities of the suited individuals. This knowledge will lead to better design of tools and planned operations. Mission planners can use the modeling system and view the animations and the visualizations of the various parameters, such as overall fatigue, motion, timelines, reach, and strength to streamline the timing, duration, task arrangement, personnel and overall efficiency of the EVA tasks. Suit designers can use quantifiable data at common biomechanical structure points to better analyze and compare suit performance.

  17. Second generation copolymers for EOR

    SciTech Connect

    McCormick, C.L.

    1988-05-01

    In this report, the authors review four types of acrylamide-based copolymers with distinctly different dilute solutions and rheological behavior. Each of these ''second generation'' systems possesses characteristics which, in theory, should be superior to conventional polymers under certain operational conditions. Type I copolymers are prepared from acrylamide (AM) and sodium-3-acrylamido-3-methylbutanoate (NaAMB). The high molecular weight, viscosity maintenance, and phase stability in the presence of divalent ions make these copolymers especially attractive for mobility control in EOR. Type II copolymers address the problems of entrapment, pore clogging, and shear degradation often encountered with ultrahigh molecular weight copolymers. The copolymers of this type are lower molecular weight than Type 1 but associate in a cooperative manner in semi-dilute solutions to enhance solution viscoscity. In this report, the authors discuss associative polymers of acrylamide/N-alkyl acrylamides which contain low mole percentages of C/sub 8/, C/sub 10/, or C/sub 12/ comonomers. In practice, a third charged comonomer such as carboxylated or sulfonated one, might be necessary to reduce adsorption to reservoir rock. Type III systems are relatively low molecular weight and hyrophibically modified in order to bring about intramolecular micelle-like association in aqueous solution. The aqueous solutions are non-viscous; viscosification occurs upon solubilization of hydrocarbons in the hydrophobic domains. Copolymers of acrylamide with N-propyl diacetone acrylamide are examples of Type III.

  18. Extravehicular Activity/Air Traffic Control (EVA/ATC) test report. [communication links to the astronaut

    NASA Technical Reports Server (NTRS)

    Tomaro, D. J.

    1982-01-01

    During extravehicular activity (EVA), communications between the EVA astronaut and the space shuttle orbiter are maintained by means of transceiver installed in the environmental support system backpack. Onboard the orbiter, a transceiver line replaceable unit and its associated equipment performs the task of providing a communications link to the astronaut in the extravehicular activity/air traffic control (EVA/ATC) mode. Results of the acceptance tests that performed on the system designed and fabricated for EVA/ATC testing are discussed.

  19. The role of EVA on Space Shuttle. [experimental support and maintenance activities

    NASA Technical Reports Server (NTRS)

    Carson, M. A.

    1974-01-01

    The purpose of this paper is to present the history of Extravehicular Activity (EVA) through the Skylab Program and to outline the expected tasks and equipment capabilities projected for the Space Shuttle Program. Advantages offered by EVA as a tool to extend payload capabilities and effectiveness and economic advantages of using EVA will be explored. The presentation will conclude with some guidelines and recommendations for consideration by payload investigators in establishing concepts and designs utilizing EVA support.

  20. Electrostatic Discharge Issues in International Space Station Program EVAs

    NASA Technical Reports Server (NTRS)

    Bacon, John B.

    2009-01-01

    EVA activity in the ISS program encounters several dangerous ESD conditions. The ISS program has been aggressive for many years to find ways to mitigate or to eliminate the associated risks. Investments have included: (1) Major mods to EVA tools, suit connectors & analytical tools (2) Floating Potential Measurement Unit (3) Plasma Contactor Units (4) Certification of new ISS flight attitudes (5) Teraflops of computation (6) Thousands of hours of work by scores of specialists (7) Monthly management attention at the highest program levels. The risks are now mitigated to a level that is orders of magnitude safer than prior operations

  1. Medical, Psychophysiological, and Human Performance Problems During Extended EVA

    NASA Technical Reports Server (NTRS)

    1997-01-01

    In this session, Session JP1, the discussion focuses on the following topics: New Developments in the Assessment of the Risk of Decompression Sickness in Null Gravity During Extravehicular Activity; The Dynamic of Physiological Reactions of Cosmonauts Under the Influence of Repeated EVA Workouts, The Russian Experience; Medical Emergencies in Space; The Evolution from 'Physiological Adequacy' to 'Physiological Tuning'; Five Zones of Symmetrical and Asymmetrical Conflicting Temperatures on the Human Body, Physiological Consequences; Human Performance and Subjective Perception in Nonuniform Thermal Conditions; The Hand as a Control System, Implications for Hand-Finger Dexterity During Extended EVA; and Understanding the Skill of Extravehicular Mass Handling.

  2. Astronaut Jack Lousma seen outside Skylab space station during EVA

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Astronaut Jack R. Lousma, Skylab 3 pilot, is seen outside the Skylab space station in Earth orbit during the August 5, 1973 Skylab 3 extravehicular activity (EVA) in this photographic reproduction taken from a television transmission made by a color TV camera aboard the space station. Lousma is at the Apollo Telescope Mount EVA work station assembling one of the two 55-foot long sectionalized poles for the twin pole solar shield which was deployed to help cool the Orbital Workshop. Part of the Airlock Module's thermal/meteoroid curtain is in the left foreground.

  3. EVA crew workstation provisions for Skylab and Space Shuttle missions

    NASA Technical Reports Server (NTRS)

    Brown, N. E.; Saenger, E. L.

    1973-01-01

    A synopsis of scheduled extravehicular activities (EVA) for a nominal Skylab mission is presented with an overview of EV workstation equipment developed for the program. Also included are the unprogrammed extravehicular activities and supporting equipment that was quickly developed and retrofitted in a series of successful operations to salvage the crippled Skylab Cluster during the Skylab 1 Mission. Because EVA appears to be a requirement for the Space Shuttle Program, candidate EV workstations are discussed in terms of effective and economical Shuttle payload servicing and maintenance. Several such concepts, which could provide a versatile, portable EV support system, are presented.

  4. EVA 2000: A European/Russian space suit concept

    NASA Astrophysics Data System (ADS)

    Skoog, A. I.; Abramov, I. P.

    1995-07-01

    For the European manned space activities an EVA space suit system was being developed in the frame of the Hermes Space Vehicle Programme of the European Space Agency (ESA). The space suit was to serve the needs for all relevant extravehicular activities for the Hermes/Columbus operations planned to begin in 2004. For the present Russian manned space programme the relevant EVAs are performed by the Orlan-DMA semi-rigid space suit. The origin of its development reaches back to the 1970s and has since been adapted to cover the needs for extravehicular activities on Salyut and MIR until today. The latest modification of the space suit, which guaranteed its completely self-contained operation, was made in 1988. However, Russian specialists considered it necessary to start developing an EVA space suit of a new generation, which would have improved performance and would cover the needs by the turn of the century and into the beginning of the next century. Potentially these two suit developments could have a lot in common based on similarities in present concepts. As future manned space activities become more and more an international effort, a safe and reliable interoperability of the different space suit systems is required. Based on the results of the Munich Minister Conference in 1991, the European Space Agency and the Russian Space Agency agreed to initiate a requirements analysis and conceptual design study to determine the feasibility of a joint space suit development, EVA 2000. The design philosophy for the EVA 2000 study was oriented on a space suit system design of: —space suit commonality and interoperability —increased crew productivity and safety —increase in useful life and reduced maintainability —reduced development and production cost. The EVA 2000 feasibility study was performed in 1992, and with the positive conclusions for EVA 2000, this approach became the new joint European/Russian EVA Suit 2000 Development Programme. This paper gives an

  5. Layered Poly(ethylene-co-vinyl acetate)/Poly(ethylene-co-vinyl alcohol) Membranes with Enhanced Water Separation Selectivity and Performance.

    PubMed

    Soto Puente, J A; Fatyeyeva, K; Chappey, C; Marais, S; Dargent, E

    2017-02-22

    A three-layered membrane based on poly(ethylene-co-vinyl acetate) (EVA) and hydrolyzed EVA-poly(ethylene-co-vinyl alcohol) (EVOH), was elaborated by the surface hydrolysis of a dense EVA membrane. Because of the chemical modifications, the three-layered EVOH/EVA/EVOH membrane was characterized by the particular microstructure (amorphous EVA and semicrystalline EVOH) and the tunable hydrophilic/hydrophobic balance. Also, these modifications led to the membrane with the selective barrier properties compared with the pure EVA and completely hydrolyzed EVOH membranes. The water barrier behavior was related to the strong hydrogen-bond interactions of water and vinyl alcohol groups, whereas the weak chemical interactions were revealed for gases (N2 and O2). Furthermore, the influence of the polymer rubbery or glassy state on the permeation kinetics was established. In the case of the three-layered membrane, the considerably high selectivity values were obtained for H2O/O2 (∼11 900) and H2O/N2 (∼48 000) at 25 °C. In addition to these highly selective properties, the three-layered structure does not present delamination features due to its elaboration procedure. Thus, these new layered membranes are very promising as selective materials for the water and gas separation and can be potentially used in food packaging or for the gas dehydration.

  6. Post thermoforming dimensional changes of ethylene vinyl acetate used in custom-made mouthguards for trauma prevention--a pilot study.

    PubMed

    Geary, Julian Lindsay; Kinirons, Martin James

    2008-06-01

    It is important that mouthguards have an adequate thickness of material if they are to be effective in the prevention of trauma. The aim of this study was to quantify dimensional changes that occur on thermoforming ethylene vinyl acetate (EVA) sheets used in the construction of mouthguards. Fourteen batches of 3 mm thick sheet EVA were thermoformed over dental models under a number of common processing conditions including, model height, inclination, shape and model temperature, model position on thermoforming platform, plasticizing time and evacuation method. Thickness of thermoformed material was determined at anterior and posterior sites and measurements were compared to determine the magnitude and patterns of stretching collectively and within each processing condition. Overall, sheets of 3-mm EVA stretched by 52% during the thermoforming conditions tested. Incisal/cuspal sites were found to be significantly thinner when compared with all other locations measured. A number of thermoforming conditions were demonstrated to have a significant effect on the degree to which the EVA material stretched. For the combination of materials and equipment tested in this study, current thermoforming practices may cause excessive thinning of EVA in critical areas including incisal edges and cusp tips, thereby reducing the protective effect for professionally made mouthguards. To optimize protection in vulnerable areas, it is important that clinicians distinguish between EVA sheet thickness and the cross-sectional dimensions achieved in the finished mouthguards. They need to be specific in their prescription of the thickness of material they require especially in critical areas.

  7. Reducing cyclone pressure drop with evasés

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cyclones are widely used to separate particles from gas flows and as air emissions control devices. Their cost of operation is proportional to the fan energy required to overcome their pressure drop. Evasés or exit diffusers potentially could reduce exit pressure losses without affecting collection...

  8. Astronaut Richard Gordon practices attaching camera to film EVA

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Astronaut Richard F. Gordon Jr., prime crew pilot for the Gemini 11 space flight, practices attaching to a Gemini boilerplate a camera which will film his extravehicular activity (EVA) outside the spacecraft. The training exercise is being conducted in the Astronaut Training Building, Kennedy Space Center, Florida.

  9. Astronaut Alan Bean with subpackages of the ALSEP during EVA

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Astronaut Alan L. Bean, lunar module pilot, traverses with the two subpackages of the Apollo Lunar Surface Experiments Package (ALSEP) during the first Apollo 12 extravehicular activity (EVA). Bean deployed the ALSEP components 300 feet from the Lunar Module (LM). The LM and deployed erectable S-band antenna can be seen in the background.

  10. Compiling a Comprehensive EVA Training Dataset for NASA Astronauts

    NASA Technical Reports Server (NTRS)

    Laughlin, M. S.; Murray, J. D.; Lee, L. R.; Wear, M. L.; Van Baalen, M.

    2016-01-01

    Training for a spacewalk or extravehicular activity (EVA) is considered a hazardous duty for NASA astronauts. This places astronauts at risk for decompression sickness as well as various musculoskeletal disorders from working in the spacesuit. As a result, the operational and research communities over the years have requested access to EVA training data to supplement their studies. The purpose of this paper is to document the comprehensive EVA training data set that was compiled from multiple sources by the Lifetime Surveillance of Astronaut Health (LSAH) epidemiologists to investigate musculoskeletal injuries. The EVA training dataset does not contain any medical data, rather it only documents when EVA training was performed, by whom and other details about the session. The first activities practicing EVA maneuvers in water were performed at the Neutral Buoyancy Simulator (NBS) at the Marshall Spaceflight Center in Huntsville, Alabama. This facility opened in 1967 and was used for EVA training until the early Space Shuttle program days. Although several photographs show astronauts performing EVA training in the NBS, records detailing who performed the training and the frequency of training are unavailable. Paper training records were stored within the NBS after it was designated as a National Historic Landmark in 1985 and closed in 1997, but significant resources would be needed to identify and secure these records, and at this time LSAH has not pursued acquisition of these early training records. Training in the NBS decreased when the Johnson Space Center in Houston, Texas, opened the Weightless Environment Training Facility (WETF) in 1980. Early training records from the WETF consist of 11 hand-written dive logbooks compiled by individual workers that were digitized at the request of LSAH. The WETF was integral in the training for Space Shuttle EVAs until its closure in 1998. The Neutral Buoyancy Laboratory (NBL) at the Sonny Carter Training Facility near JSC

  11. Commercial Spacewalking: Designing an EVA Qualification Program for Space Tourism

    NASA Technical Reports Server (NTRS)

    Gast, Matthew A.

    2010-01-01

    In the near future, accessibility to space will be opened to anyone with the means and the desire to experience the weightlessness of microgravity, and to look out upon both the curvature of the Earth and the blackness of space, from the protected, shirt-sleeved environment of a commercial spacecraft. Initial forays will be short-duration, suborbital flights, but the experience and expertise of half a century of spaceflight will soon produce commercial vehicles capable of achieving low Earth orbit. Even with the commercial space industry still in its infancy, and manned orbital flight a number of years away, there is little doubt that there will one day be a feasible and viable market for those courageous enough to venture outside the vehicle and into the void, wearing nothing but a spacesuit, armed with nothing but preflight training. What that Extravehicular Activity (EVA) preflight training entails, however, is something that has yet to be defined. A number of significant factors will influence the composition of a commercial EVA training program, but a fundamental question remains: 'what minimum training guidelines must be met to ensure a safe and successful commercial spacewalk?' Utilizing the experience gained through the development of NASA's Skills program - designed to qualify NASA and International Partner astronauts for EVA aboard the International Space Station - this paper identifies the attributes and training objectives essential to the safe conduct of an EVA, and attempts to conceptually design a comprehensive training methodology meant to represent an acceptable qualification standard.

  12. Astronaut Harrison Schmitt standing next to boulder during third EVA

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Scientist-Astronaut Harrison H. Schmitt is photographed standing next to a huge, split boulder during the third Apollo 17 extravehicular activity (EVA-3) at the Taurus-Littrow landing site on the Moon. Schmitt is the Apollo 17 lunar module pilot. This picture was taken by Astronaut Eugene A. Cernan, commander.

  13. Television transmission of Astronaut Harrison Schmitt falling during EVA

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Scientist-Astronaut Harrison H. Schmitt loses his balance and heads for a fall during the second Apollo 17 extravehicular activity (EVA-1) at the Taurus-Littrow landing site, in this black and white reproduction taken from a color television transmission made by the RCA color TV camera mounted on the Lunar Roving Vehicle. Schmitt is the lunar module pilot.

  14. Astronaut Harrison Schmitt retrieving lunar samples during EVA

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Scientist-Astronaut Harrison Schmitt, Apollo 17 lunar module pilot, with his adjustable sampling scoop, heads for a selected rock on the lunar surface to retrieve the sample for study. The action was photographed by Apollo 17 crew commander, Astronaut Eugene A. Cernan on the mission's second extravehicular activity (EVA-2), at Station 5 (Camelot Crater) at the Taurus-Littrow landing site.

  15. 8. LESLIE WICKMAN, EVA (EXTRA VEHICULAR ACTIVITIES) SPECIALIST, GETTING OUT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. LESLIE WICKMAN, EVA (EXTRA VEHICULAR ACTIVITIES) SPECIALIST, GETTING OUT OF SPACE SUIT AFTER TESTING IN NEUTRAL BUOYANCY TANK. AVERAGE COST OF SUIT $1,000,000. - Marshall Space Flight Center, Neutral Buoyancy Simulator Facility, Rideout Road, Huntsville, Madison County, AL

  16. Design, development and evaluation of Stanford/Ames EVA prehensors

    NASA Technical Reports Server (NTRS)

    Leifer, Larry J.; Aldrich, J.; Leblanc, M.; Sabelman, E.; Schwandt, D.

    1988-01-01

    Space Station operations and maintenance are expected to make unprecedented demands on astronaut EVA. With Space Station expected to operate with an 8 to 10 psi atmosphere (4 psi for Shuttle operations), the effectivness of pressurized gloves is called into doubt at the same time that EVA activity levels are to be increased. To address the need for more frequent and complex EVA missions and also to extend the dexterity, duration, and safety of EVA astronauts, NASA Ames and Stanford University have an ongoing cooperative agreement to explore and compare alternatives. This is the final Stanford/Ames report on manually powered Prehensors, each of which consists of a shroud forming a pressure enclosure around the astronaut's hand, and a linkage system to transfer the motions and forces of the hand to mechanical digits attached to the shroud. All prehensors are intended for attachment to a standard wrist coupling, as found on the AX-5 hard suit prototype, so that realistic tests can be performed under normal and reduced gravity as simulated by water flotation.

  17. Ordering Chaos: Eva Miller--Multnomah County Library, Portland, OR

    ERIC Educational Resources Information Center

    Library Journal, 2004

    2004-01-01

    Eva Miller has a knack for creating order out of disorder. She single-handedly brought Oregon's virtual reference service, Answerland, live in just under 90 days, says Rivkah Sass, now director of the Omaha Public Library. Miller created its web site, designed the graphics, developed marketing materials, and recruited and trained librarians--all…

  18. Polarization Processes of Nanocomposite Silicate-EVA and PP Materials

    NASA Astrophysics Data System (ADS)

    Montanari, Gian Carlo; Palmieri, Fabrizio; Testa, Luigi; Motori, Antonio; Saccani, Andrea; Patuelli, Francesca

    Recent works indicate that polypropylene (PP) and ethylene-vinylacetate (EVA) filled by nanosilicates may present low content of space charge and high electric strength. Investigations are being made to explain nanocomposite behaviour and characterize their electrical, thermal and mechanical properties. In this paper, the results of broad-band dielectric spectroscopy performed on EVA and PP filled by layered nanosized silicates are reported. Isochronal and isothermal curves of complex permittivity, as well as activation energies of the relaxation processes, are presented and discussed. Nanostructuration gives rise to substantial changes in the polarisation and dielectric loss behaviour. While the relaxation process of EVA, associated with glass transition of the material amorphous phase, results unchanged from base to nanostructured material, nanocomposites EVA and PP have shown the rise of a new process at higher temperatures respect to the typical host material processes, as well as a different distribution of relaxation processes. Changes in space charge accumulation in relation to the effectiveness of the purification process performed upon nanostructured materials are also reported: while the dispersion of the clean clays leads to a reduction of the space charge, especially at high fields, an unclean filler gives rise to significant homo-charge accumulation and interfacial polarisation phenomena.

  19. Astronaut James Irwin uses scoop during Apollo 15 EVA

    NASA Technical Reports Server (NTRS)

    1971-01-01

    Astronaut James B. Irwin, lunar module pilot, uses a scoop in making a trench in the lunar soil during Apollo 15 extravehicular activity (EVA). Mount Hadley rises approximately 14,765 feet (about 4,500 meters) above the plain in the background.

  20. EVA Metro Sedan Electric Propulsion System Test and Evaluation.

    DTIC Science & Technology

    1979-09-01

    This report provides the procedure and results of the performance evaluation of an EVA Metro Sedan propulsion system. Data is provided for the automatic transmission, solid state dc motor controller and the dc motor as well as the entire propulsion system. Algorithms used on the automatic data acquisition system are included. (Author)

  1. EVA: Collaborative Distributed Learning Environment Based in Agents.

    ERIC Educational Resources Information Center

    Sheremetov, Leonid; Tellez, Rolando Quintero

    In this paper, a Web-based learning environment developed within the project called Virtual Learning Spaces (EVA, in Spanish) is presented. The environment is composed of knowledge, collaboration, consulting, experimentation, and personal spaces as a collection of agents and conventional software components working over the knowledge domains. All…

  2. EVA: An Interactive Web-Based Collaborative Learning Environment

    ERIC Educational Resources Information Center

    Sheremetov, Leonid; Arenas, Adolfo Guzman

    2002-01-01

    In this paper, a Web-based learning environment developed within the project called Virtual Learning Spaces (EVA, in Spanish) is described. The environment is composed of knowledge, collaboration, consulting and experimentation spaces as a collection of agents and conventional software components working over the knowledge domains. All user…

  3. Space Station Human Factors Research Review. Volume 1: EVA Research and Development

    NASA Technical Reports Server (NTRS)

    Cohen, Marc M. (Editor); Vykukal, H. C. (Editor)

    1988-01-01

    An overview is presented of extravehicular activity (EVA) research and development activities at Ames. The majority of the program was devoted to presentations by the three contractors working in parallel on the EVA System Phase A Study, focusing on Implications for Man-Systems Design. Overhead visuals are included for a mission results summary, space station EVA requirements and interface accommodations summary, human productivity study cross-task coordination, and advanced EVAS Phase A study implications for man-systems design. Articles are also included on subsea approach to work systems development and advanced EVA system design requirements.

  4. Fabrication and Properties of Ethylene Vinyl Acetate-Carbon Nanofiber Nanocomposites

    PubMed Central

    2008-01-01

    Carbon nanofiber (CNF) is one of the stiffest materials produced commercially, having excellent mechanical, electrical, and thermal properties. The reinforcement of rubbery matrices by CNFs was studied in the case of ethylene vinyl acetate (EVA). The tensile strength was greatly (61%) increased, even for very low fiber content (i.e., 1.0 wt.%). The surface modification of the fiber by high energy electron beam and gamma irradiation led to better dispersion in the rubber matrix. This in turn gave rise to further improvements in mechanical and dynamic mechanical properties of EVA. The thermal conductivity also exhibited improvements from that of the neat elastomer, although thermal stability of the nanocomposites was not significantly altered by the functionalization of CNFs. Various results were well supported by the morphological analysis of the nanocomposites. PMID:20596388

  5. Nitroxide-mediated radical ring-opening copolymerization: chain-end investigation and block copolymer synthesis.

    PubMed

    Delplace, Vianney; Harrisson, Simon; Tardy, Antoine; Gigmes, Didier; Guillaneuf, Yohann; Nicolas, Julien

    2014-02-01

    Well-defined, degradable copolymers are successfully prepared by nitroxide-mediated radical ring opening polymerization (NMrROP) of oligo(ethylene glycol) methyl ether methacrylate (OEGMA) or methyl methacrylate (MMA), a small amount of acrylonitrile (AN) and cyclic ketene acetals (CKAs) of different structures. Phosphorous nuclear magnetic resonance allows in-depth chain-end characterization and gives crucial insights into the nature of the copoly-mer terminal sequences and the living chain fractions. By using a small library of P(OEGMA-co-AN-co-CKA) and P(MMA-co-AN-co-CKA) as macroinitiators, chain extensions with styrene are performed to furnish (amphiphilic) block copolymers comprising a degradable segment.

  6. Asteroid Redirect Crewed Mission Space Suit and EVA System Maturation

    NASA Technical Reports Server (NTRS)

    Bowie, Jonathan T.; Kelly, Cody; Buffington, Jesse; Watson, Richard D.

    2015-01-01

    The Asteroid Redirect Crewed Mission (ARCM) requires a Launch/Entry/Abort (LEA) suit capability and short duration Extra Vehicular Activity (EVA) capability from the Orion spacecraft. For this mission, the pressure garment that was selected, for both functions, is the Modified Advanced Crew Escape Suit (MACES) with EVA enhancements and the life support option that was selected is the Exploration Portable Life Support System (PLSS). The proposed architecture was found to meet the mission constraints, but much more work is required to determine the details of the required suit upgrades, the integration with the PLSS, and the rest of the tools and equipment required to accomplish the mission. This work has continued over the last year to better define the operations and hardware maturation of these systems. EVA simulations have been completed in the NBL and interfacing options have been prototyped and analyzed with testing planned for late 2014. For NBL EVA simulations, in 2013, components were procured to allow in-house build up for four new suits with mobility enhancements built into the arms. Boots outfitted with clips that fit into foot restraints have also been added to the suit and analyzed for possible loads. Major suit objectives accomplished this year in testing include: evaluation of mobility enhancements, ingress/egress of foot restraint, use of foot restraint for worksite stability, ingress/egress of Orion hatch with PLSS mockup, and testing with two crew members in the water at one time to evaluate the crew's ability to help one another. Major tool objectives accomplished this year include using various other methods for worksite stability, testing new methods for asteroid geologic sampling and improving the fidelity of the mockups and crew equipment. These tests were completed on a medium fidelity capsule mockup, asteroid vehicle mockup, and asteroid mockups that were more accurate for an asteroid type EVA than previous tests. Another focus was the

  7. 21 CFR 177.2470 - Polyoxymethylene copolymer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... copolymer when extracted for 6 hours with distilled water at reflux temperature. (ii) Not to exceed 0.15 percent by weight of the copolymer when extracted for 6 hours with n-heptane at reflux temperature....

  8. Lignin poly(lactic acid) copolymers

    DOEpatents

    Olsson, Johan Vilhelm; Chung, Yi-Lin; Li, Russell Jingxian; Waymouth, Robert; Sattely, Elizabeth; Billington, Sarah; Frank, Curtis W.

    2017-02-14

    Provided herein are graft co-polymers of lignin and poly(lactic acid) (lignin-g-PLA copolymer), thermoset and thermoplastic polymers including them, methods of preparing these polymers, and articles of manufacture including such polymers.

  9. Acid-Cleavable Unimolecular Micelles from Amphiphilic Star Copolymers for Triggered Release of Anticancer Drugs.

    PubMed

    Zhang, Shan; Xu, Jianbin; Chen, Heng; Song, Zhangfa; Wu, Yalan; Dai, Xingyi; Kong, Jie

    2017-03-01

    In this contribution, amphiphilic star copolymers (H40-star-PCL-a-PEG) with an H40 hyperbranched polyester core and poly(ε-caprolactone)-a-poly(ethylene glycol) copolymer arms linked with acetal groups are synthesized using ring-opening polymerization and a copper (I)-catalyzed alkyne-azide cycloaddition click reaction. The acid-cleavable acetal groups between the hydrophilic and hydrophobic segments of the arms endow the amphiphilic star copolymers with pH responsiveness. In aqueous solution, unimolecular micelles can be formed with good stability and a unique acid degradability, as is desirable for anticancer drug carriers. For the model drug of doxorubicin, the in vitro release behavior, intracellular release, and inhibition of proliferation of HeLa cells show that the acid-cleavable unimolecular micelles with anticancer activity can be dissociated in an acidic environment and efficiently internalized by HeLa cells. Due to the acid-cleavable and biodegradable nature, unimolecular micelles from amphiphilic star copolymers are promising for applications in intracellular drug delivery for cancer chemotherapy.

  10. High Performance EVA Glove Collaboration: Glove Injury Data Mining Effort

    NASA Technical Reports Server (NTRS)

    Reid, C. R.; Benson, E.; England, S.; Charvat, J.; Norcross, J. R.; McFarland, S. M.; Rajulu, S.

    2015-01-01

    Human hands play a significant role during Extravehicular Activity (EVA) missions and Neutral Buoyancy Lab (NBL) training events, as they are needed for translating and performing tasks in the weightless environment. Because of this high frequency usage, hand and arm related injuries are known to occur during EVA and EVA training in the NBL. The primary objectives of this investigation were to: 1) document all known EVA glove related injuries and circumstances of these incidents, 2) determine likely risk factors, and 3) recommend interventions where possible that could be implemented in the current and future glove designs. METHODS: The investigation focused on the discomforts and injuries of U.S. crewmembers who had worn the pressurized Extravehicular Mobility Unit (EMU) spacesuit and experienced 4000 Series or Phase VI glove related incidents during 1981 to 2010 for either EVA ground training or in-orbit flight. We conducted an observational retrospective case-control investigation using 1) a literature review of known injuries, 2) data mining of crew injury, glove sizing, and hand anthropometry databases, 3) descriptive statistical analyses, and finally 4) statistical risk correlation and predictor analyses to better understand injury prevalence and potential causation. Specific predictor statistical analyses included use of principal component analyses (PCA), multiple logistic regression, and survival analyses (Cox proportional hazards regression). Results of these analyses were computed risk variables in the forms of odds ratios (likelihood of an injury occurring given the magnitude of a risk variable) and hazard ratios (likelihood of time to injury occurrence). Due to the exploratory nature of this investigation, we selected predictor variables significant at p=0.15. RESULTS: Through 2010, there have been a total of 330 NASA crewmembers, from which 96 crewmembers performed 322 EVAs during 1981-2010, resulting in 50 crewmembers being injured inflight and 44

  11. 21 CFR 173.65 - Divinylbenzene copolymer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... CONSUMPTION Polymer Substances and Polymer Adjuvants for Food Treatment § 173.65 Divinylbenzene copolymer. Divinylbenzene copolymer may be used for the removal of organic substances from aqueous foods under the following... contacting the polymer is maintained at 79.4 °C (175 °F) or less. (d) The copolymer may be used in...

  12. A mobile transporter concept for EVA assembly of future spacecraft

    NASA Technical Reports Server (NTRS)

    Watson, Judith J.; Bush, Harold G.; Heard, Walter L., Jr.; Lake, Mark S.; Jensen, J. Kermit

    1990-01-01

    This paper details the ground test program for the NASA Langley Research Center Mobile Transporter concept. The Mobile Transporter would assist EVA astronauts in the assembly of the Space Station Freedom. 1-g and simulated O-g (neutral buoyancy) tests were conducted to evaluate the use of the Mobile Transporter. A three-bay (44 struts) orthogonal tetrahedral truss configuration with a 15-foot-square cross section was repeatedly assembled by a single pair of pressure suited test subjects working from the Mobile Transporter astronaut positioning devices. The average unit assembly time was 28 seconds/strut. The results of these tests indicate that the use of a Mobile Transporter for EVA assembly of Space Station size structure is viable and practical. Additionally, the Mobile Transporter could be used to construct other spacecraft such as the submillimeter astronomical laboratory, space crane, and interplanetary (i.e., Mars and lunar) spacecraft.

  13. High-Pressure Oxygen Generation for Outpost EVA Study

    NASA Technical Reports Server (NTRS)

    Jeng, Frank F.; Conger, Bruce; Ewert, Michael K.; Anderson, Molly S.

    2009-01-01

    The amount of oxygen consumption for crew extravehicular activity (EVA) in future lunar exploration missions will be significant. Eight technologies to provide high pressure EVA O2 were investigated. They are: high pressure O2 storage, liquid oxygen (LOX) storage followed by vaporization, scavenging LOX from Lander followed by vaporization, LOX delivery followed by sorption compression, water electrolysis followed by compression, stand-alone high pressure water electrolyzer, Environmental Control and Life Support System (ECLSS) and Power Elements sharing a high pressure water electrolyzer, and ECLSS and In-Situ Resource Utilization (ISRU) Elements sharing a high pressure electrolyzer. A trade analysis was conducted comparing launch mass and equivalent system mass (ESM) of the eight technologies in open and closed ECLSS architectures. Technologies considered appropriate for the two architectures were selected and suggested for development.

  14. EVA Development and Verification Testing at NASA's Neutral Buoyancy Laboratory

    NASA Technical Reports Server (NTRS)

    Jairala, Juniper; Durkin, Robert

    2012-01-01

    As an early step in preparing for future EVAs, astronauts perform neutral buoyancy testing to develop and verify EVA hardware and operations. To date, neutral buoyancy demonstrations at NASA JSC’s Sonny Carter Training Facility have primarily evaluated assembly and maintenance tasks associated with several elements of the ISS. With the retirement of the Space Shuttle, completion of ISS assembly, and introduction of commercial participants for human transportation into space, evaluations at the NBL will take on a new focus. In this session, Juniper Jairala briefly discussed the design of the NBL and, in more detail, described the requirements and process for performing a neutral buoyancy test, including typical hardware and support equipment requirements, personnel and administrative resource requirements, examples of ISS systems and operations that are evaluated, and typical operational objectives that are evaluated. Robert Durkin discussed the new and potential types of uses for the NBL, including those by non-NASA external customers.

  15. EVA Development and Verification Testing at NASA's Neutral Buoyancy Laboratory

    NASA Technical Reports Server (NTRS)

    Jairala, Juniper; Durkin, Robert

    2012-01-01

    As an early step in preparing for future EVAs, astronauts perform neutral buoyancy testing to develop and verify EVA hardware and operations. To date, neutral buoyancy demonstrations at NASA JSC's Sonny Carter Training Facility have primarily evaluated assembly and maintenance tasks associated with several elements of the ISS. With the retirement of the Space Shuttle, completion of ISS assembly, and introduction of commercial participants for human transportation into space, evaluations at the NBL will take on a new focus. In this session, Juniper Jairala briefly discussed the design of the NBL and, in more detail, described the requirements and process for performing a neutral buoyancy test, including typical hardware and support equipment requirements, personnel and administrative resource requirements, examples of ISS systems and operations that are evaluated, and typical operational objectives that are evaluated. Robert Durkin discussed the new and potential types of uses for the NBL, including those by non-NASA external customers.

  16. Study of EVA operations associated with satellite services

    NASA Technical Reports Server (NTRS)

    Nash, J. O.; Wilde, R. D.

    1982-01-01

    Extravehicular mobility unit (EMU) factors associated with satellite servicing activities are identified and the EMU improvements necessary to enhance satellite servicing operations are outlined. Areas of EMU capabilities, equipment and structural interfaces, time lines, EMU modifications for satellite servicing, environmental hazards, and crew training are vital to manned Eva/satellite services and as such are detailed. Evaluation of EMU capabilities indicates that the EMU can be used in performing near term, basic satellite servicing tasks; however, satellite servicing is greatly enhanced by incorporating key modifications into the EMU. The servicing missions involved in contamination sensitive payload repair are illustrated. EVA procedures and equipment can be standardized, reducing both crew training time and in orbit operations time. By standardizing and coordinating procedures, mission cumulative time lines fall well within the EMU capability.

  17. Copolymers For Capillary Gel Electrophoresis

    SciTech Connect

    Liu, Changsheng; Li, Qingbo

    2005-08-09

    This invention relates to an electrophoresis separation medium having a gel matrix of at least one random, linear copolymer comprising a primary comonomer and at least one secondary comonomer, wherein the comonomers are randomly distributed along the copolymer chain. The primary comonomer is an acrylamide or an acrylamide derivative that provides the primary physical, chemical, and sieving properties of the gel matrix. The at least one secondary comonomer imparts an inherent physical, chemical, or sieving property to the copolymer chain. The primary and secondary comonomers are present in a ratio sufficient to induce desired properties that optimize electrophoresis performance. The invention also relates to a method of separating a mixture of biological molecules using this gel matrix, a method of preparing the novel electrophoresis separation medium, and a capillary tube filled with the electrophoresis separation medium.

  18. Astronaut Harrison Schmitt standing next to boulder during third EVA

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Scientist-Astronaut Harrison H. Schmitt is photographed standing next to a huge, split boulder at Station 6 (base of North Massif) during the third Apollo 17 extravehicular activity (EVA-3) at the Taurus-Littrow landing site on the Moon. Notice the Lunar Roving Vehicle (LRV) in the left foreground. Schmitt is the Apollo 17 lunar module pilot. This picture was taken by Astronaut Eugene A. Cernan, commander.

  19. Astronaut Harrison Schmitt standing next to boulder during third EVA

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Scientist-Astronaut Harrison H. Schmitt is photographed standing next to a huge, split boulder during the third Apollo 17 extravehicular activity (EVA-3) at the Taurus-Littrow landing site on the Moon. The lunar rover, which transported Schmitt and Eugene A. Cernan, mission commander, to this extravehicular station from their Lunar Module, is seen in the background. Schmitt is the Apollo 17 lunar module pilot. The mosaic is made from two frames from Apollo 17 Hasselblad magaine 140.

  20. Non-Venting Thermal and Humidity Control for EVA Suits

    NASA Technical Reports Server (NTRS)

    Izenson, Mike; Chen, Weibo; Bue, Grant

    2011-01-01

    Future EVA suits need processes and systems to control internal temperature and humidity without venting water to the environment. This paper describes an absorption-based cooling and dehumidification system as well as laboratory demonstrations of the key processes. There are two main components in the system: an evaporation cooling and dehumidification garment (ECDG) that removes both sensible heat and latent heat from the pressure garment, and an absorber radiator that absorbs moisture and rejects heat to space by thermal radiation. This paper discusses the overall design of both components, and presents recent data demonstrating their operation. We developed a design and fabrication approach to produce prototypical heat/water absorbing elements for the ECDG, and demonstrated by test that these elements could absorb heat and moisture at a high flux. Proof-of-concept tests showed that an ECDG prototype absorbs heat and moisture at a rate of 85 W/ft under conditions that simulate operation in an EVA suit. The heat absorption was primarily due to direct absorption of water vapor. It is possible to construct large, flexible, durable cooling patches that can be incorporated into a cooling garment with this system. The proof-of-concept test data was scaled to calculate area needed for full metabolic loads, thus showing that it is feasible to use this technology in an EVA suit. Full-scale, lightweight absorber/radiator modules have also been built and tested. They can reject heat at a flux of 33 W/ft while maintaining ECDG operation at conditions that will provide a cool and dry environment inside the EVA suit.

  1. Enhanced Controlled Transdermal Delivery of Ambroxol from the EVA Matrix

    PubMed Central

    Cho, C. W.; Kim, D. B.; Cho, H. W.; Shin, S. C.

    2012-01-01

    To avoid the systemic adverse effects that might occur after oral administration, transdermal delivery of ambroxol was studied as a method for maintaining proper blood levels for an extended period. Release of ambroxol according to concentration and temperature was determined, and permeation of drug through rat skin was studied using two chamber-diffusion cells. The solubility according to PEG 400 volume fraction was highest at 40% PEG 400. The rate of drug release from the EVA matrix increased with increased temperature and drug loading doses. A linear relationship existed between the release rate and the square root of loading rate. The activation energy (Ea) was measured from the slope of the plot of log P versus 1000/T and was found to be 10.71, 10.39, 10.33 and 9.87 kcal/mol for 2, 3, 4 and 5% loading dose from the EVA matrix, respectively. To increase the permeation rate of ambroxol across rat skin from the EVA matrix, various penetration enhancers such as fatty acids (saturated, unsaturated), propylene glycols, glycerides, pyrrolidones, and non-ionic surfactants were used. The enhancing effects of the incorporated enhancers on the skin permeation of ambroxol were evaluated using Franz diffusion cells fitted with intact excised rat skin at 37° using 40% PEG 400 solution as a receptor medium. Among the enhancers used, polyoxyethylene-2-oleyl ether increased the permeation rate by 4.25-fold. In conclusion, EVA matrix containing plasticizer and permeation enhancer could be developed for enhanced transdermal delivery of ambroxol. PMID:23325993

  2. NEEMO 21: Tools, Techniques, Technologies & Training for Science Exploration EVA

    NASA Technical Reports Server (NTRS)

    Graff, Trevor

    2016-01-01

    The 21st mission of the NASA Extreme Environment Mission Operations (NEEMO) was a highly integrated operational test and evaluation of tools, techniques, technologies, and training for science driven exploration during Extravehicular Activity (EVA).The 16-day mission was conducted from the Aquarius habitat, an underwater laboratory, off the coast of Key Largo, FL. The unique facility, authentic science objectives, and diverse skill-sets of the crew/team facilitate the planning and design for future space exploration.

  3. Apollo 16 lunar module 'Orion' photographed from distance during EVA

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The Apollo 16 Lunar Module 'Orion' is photographed from a distance by Astronaut Chares M. Duke Jr., lunar module pilot, aboard the moving Lunar Roving Vehicle. Astronauts Duke and John W. Young, commander, were returing from the third Apollo 16 extravehicular activity (EVA-2). The RCA color television camera mounted on the LRV is in the foreground. A portion of the LRV's high-gain antenna is at top left.

  4. Asteroid Redirect Crewed Mission Space Suit and EVA System Maturation

    NASA Technical Reports Server (NTRS)

    Bowie, Jonathan; Buffington, Jesse; Hood, Drew; Kelly, Cody; Naids, Adam; Watson, Richard

    2015-01-01

    The Asteroid Redirect Crewed Mission (ARCM) requires a Launch/Entry/Abort (LEA) suit capability and short duration Extra Vehicular Activity (EVA) capability from the Orion spacecraft. For this mission, the pressure garment selected for both functions is the Modified Advanced Crew Escape Suit (MACES) with EVA enhancements and the life support option that was selected is the Exploration Portable Life Support System (PLSS) currently under development for Advanced Exploration Systems (AES). The proposed architecture meets the ARCM constraints, but much more work is required to determine the details of the suit upgrades, the integration with the PLSS, and the tools and equipment necessary to accomplish the mission. This work has continued over the last year to better define the operations and hardware maturation of these systems. EVA simulations were completed in the Neutral Buoyancy Lab (NBL) and interfacing options were prototyped and analyzed with testing planned for late 2014. This paper discusses the work done over the last year on the MACES enhancements, the use of tools while using the suit, and the integration of the PLSS with the MACES.

  5. EVA Development and Verification Testing at NASA's Neutral Buoyancy Laboratory

    NASA Technical Reports Server (NTRS)

    Jairala, Juniper C.; Durkin, Robert; Marak, Ralph J.; Sipila, Stepahnie A.; Ney, Zane A.; Parazynski, Scott E.; Thomason, Arthur H.

    2012-01-01

    As an early step in the preparation for future Extravehicular Activities (EVAs), astronauts perform neutral buoyancy testing to develop and verify EVA hardware and operations. Neutral buoyancy demonstrations at NASA Johnson Space Center's Sonny Carter Training Facility to date have primarily evaluated assembly and maintenance tasks associated with several elements of the International Space Station (ISS). With the retirement of the Shuttle, completion of ISS assembly, and introduction of commercial players for human transportation to space, evaluations at the Neutral Buoyancy Laboratory (NBL) will take on a new focus. Test objectives are selected for their criticality, lack of previous testing, or design changes that justify retesting. Assembly tasks investigated are performed using procedures developed by the flight hardware providers and the Mission Operations Directorate (MOD). Orbital Replacement Unit (ORU) maintenance tasks are performed using a more systematic set of procedures, EVA Concept of Operations for the International Space Station (JSC-33408), also developed by the MOD. This paper describes the requirements and process for performing a neutral buoyancy test, including typical hardware and support equipment requirements, personnel and administrative resource requirements, examples of ISS systems and operations that are evaluated, and typical operational objectives that are evaluated.

  6. UV aging and outdoor exposure correlation for EVA PV encapsulants

    NASA Astrophysics Data System (ADS)

    Reid, Charles G.; Bokria, Jayesh G.; Woods, Joseph T.

    2013-09-01

    A widely cited approximation in the solar industry is that "one week of xenon arc weather-o-meter exposure is equivalent to one year of field exposure." This statement is a generalization of test data generated in the mid-1990s as part of the NREL managed PVMaT-3 project. This approximation was based entirely upon yellowing of first generation EVA-based encapsulants in two different accelerated test conditions, xenon arc and mirror accelerated outdoor aging. First generation EVA encapsulants were developed by STR under the JPL solar project (1975-1986) and exhibit yellowing (or browning) with exposure to UV and heat. This yellowing mechanism was understood and resolved with newer generation EVA encapsulation products introduced in late 1990s. Modules were manufactured at the end of the PVMaT-3 project that included both older and newer generation encapsulants. Those modules were on a two-axis tracker in Arizona from 1996 to 2012 and are now undergoing diagnostic tests. Older generation standard-cure encapsulant used in these modules exhibited severe browning over cells and the modules exhibit approximate power loss of about two percent per year. This same standard cure encapsulant material has been tested with updated xenon arc exposure methods and optical transmission tests to estimate the loss in power due only to browning and reduction in light transmission.

  7. Next Generation Life Support: High Performance EVA Glove

    NASA Technical Reports Server (NTRS)

    Walsh, Sarah K.

    2015-01-01

    The objectives of the High Performance EVA Glove task are to develop advanced EVA gloves for future human space exploration missions and generate corresponding standards by which progress may be quantitatively assessed. New technologies and manufacturing techniques will be incorporated into the new gloves to address finger and hand mobility, injury reduction and durability in nonpristine environments. Three prototypes will be developed, each focusing on different technological advances. A robotic assist glove will integrate a powered grasping system into the current EVA glove design to reduce astronaut hand fatigue and hand injuries. A mechanical counter pressure (MCP) glove will be developed to further explore the potential of MCP technology and assess its capability for countering the effects of vacuum or low pressure environments on the body by using compression fabrics or materials to apply the necessary pressure. A gas pressurized glove, incorporating new technologies, will be the most flight-like of the three prototypes. Advancements include the development and integration of aerogel insulation, damage sensing components, dust-repellant coatings, and dust tolerant bearings.

  8. Maturing Pump Technology for EVA Applications in a Collaborative Environment

    NASA Technical Reports Server (NTRS)

    Hodgson, Edward; Dionne, Steven; Gervais, Edward; Anchondo, Ian

    2012-01-01

    The transition from low earth orbit Extravehicular Activity (EVA) for construction and maintenance activities to planetary surface EVA on asteroids, moons, and, ultimately, Mars demands a new spacesuit system. NASA's development of that system has resulted in dramatically different pumping requirements from those in the current spacesuit system. Hamilton Sundstrand, Cascon, and NASA are collaborating to develop and mature a pump that will reliably meet those new requirements in space environments and within the design constraints imposed by spacesuit system integration. That collaboration, which began in the NASA purchase of a pump prototype for test evaluation, is now entering a new phase of development. A second generation pump reflecting the lessons learned in NASA's testing of the original prototype will be developed under Hamilton Sundstrand internal research funding and ultimately tested in an integrated Advanced Portable Life Support System (APLSS) in NASA laboratories at the Johnson Space Center. This partnership is providing benefit to both industry and NASA by supplying a custom component for EVA integrated testing at no cost to the government while providing test data for industry that would otherwise be difficult or impossible to duplicate in industry laboratories. This paper discusses the evolving collaborative process, component requirements and design development based on early NASA test experience, component stand alone test results, and near term plans for integrated testing at JSCs.

  9. Crystalline imide/arylene ether copolymers

    NASA Technical Reports Server (NTRS)

    Jensen, Brian J. (Inventor); Hergenrother, Paul M. (Inventor); Bass, Robert G. (Inventor)

    1995-01-01

    Crystalline imide/arylene ether block copolymers are prepared by reacting anhydride terminated poly(amic acids) with amine terminated poly)arylene ethers) in polar aprotic solvents and chemically or thermally cyclodehydrating the resulting intermediate poly(amic acids). The block copolymers of the invention have one glass transition temperature or two, depending on the particular structure and/or the compatibility of the block units. Most of these crystalline block copolymers for tough, solvent resistant films with high tensile properties. While all of the copolymers produced by the present invention are crystalline, testing reveals that copolymers with longer imide blocks or higher imide content have increased crystallinity.

  10. Extravehicular activities limitations study. Volume 2: Establishment of physiological and performance criteria for EVA gloves

    NASA Technical Reports Server (NTRS)

    Ohara, John M.; Briganti, Michael; Cleland, John; Winfield, Dan

    1988-01-01

    One of the major probelms faced in Extravehicular Activity (EVA) glove development has been the absence of concise and reliable methods to measure the effects of EVA gloves on human hand capabilities. This report describes the development of a standardized set of tests designed to assess EVA-gloved hand capabilities in six measurement domains: Range of Motion, Strength, Tactile Perception, Dexterity, Fatigue, and Comfort. Based on an assessment of general human hand functioning and EVA task requirements several tests within each measurement domain were developed to provide a comprehensive evaluation. All tests were designed to be conducted in a glove box with the bare hand as a baseline and the EVA glove at operating pressure. A test program was conducted to evaluate the tests using a representative EVA glove. Eleven test subjects participated in a repeated-measures design. The report presents the results of the tests in each capability domain.

  11. Acetal-linked polymeric prodrug micelles for enhanced curcumin delivery.

    PubMed

    Li, Man; Gao, Min; Fu, Yunlan; Chen, Chao; Meng, Xuan; Fan, Aiping; Kong, Deling; Wang, Zheng; Zhao, Yanjun

    2016-04-01

    On-demand curcumin delivery via stimuli-responsive micellar nanocarriers holds promise for addressing its solubility and stability problem. Polymer-curcumin prodrug conjugate micelle is one of such nanosystems. The diversity of linker and conjugation chemistry enabled the generation and optimization of different curcumin micelles with tunable stimuli-responsiveness and delivery efficiency. The aim of the current work was to generate and assess acetal-linked polymeric micelles to enrich the pH-responsive curcumin delivery platforms. Curcumin was slightly modified prior to conjugating to amphiphilic methoxy poly(ethylene glycol)-poly(lactic acid) (mPEG-PLA) copolymer via an acetal bond, whereas an ester bond-linked conjugate was used as the control. The acetal-containing micelles showed a hydrodynamic diameter of 91.1 ± 2.9(nm) and the accompanying core size of 63.5 ± 7.1 (nm) with a zeta potential of -10.9 ± 0.7(mV). Both control and pH-labile micelles displayed similar critical micelle concentration at 1.6 μM. The acetal-containing nanocarriers exhibited a pH-dependent drug release behavior, which was faster at lower pH values. The cytotoxicity study in HepG2 cells revealed a significantly lower IC50 at 51.7 ± 9.0(μM) for acetal-linked micelles in contrast to the control at 103.0 ± 17.8(μM), but the polymer residue showed no cytotoxicity upon drug release. The acetal-linked micellar nanocarrier could be a useful addition to the spectrum of currently available stimuli-responsive curcumin nano-formulations.

  12. Acetate Kinase Isozymes Confer Robustness in Acetate Metabolism

    PubMed Central

    Chan, Siu Hung Joshua; Nørregaard, Lasse; Solem, Christian; Jensen, Peter Ruhdal

    2014-01-01

    Acetate kinase (ACK) (EC no: 2.7.2.1) interconverts acetyl-phosphate and acetate to either catabolize or synthesize acetyl-CoA dependent on the metabolic requirement. Among all ACK entries available in UniProt, we found that around 45% are multiple ACKs in some organisms including more than 300 species but surprisingly, little work has been done to clarify whether this has any significance. In an attempt to gain further insight we have studied the two ACKs (AckA1, AckA2) encoded by two neighboring genes conserved in Lactococcus lactis (L. lactis) by analyzing protein sequences, characterizing transcription structure, determining enzyme characteristics and effect on growth physiology. The results show that the two ACKs are most likely individually transcribed. AckA1 has a much higher turnover number and AckA2 has a much higher affinity for acetate in vitro. Consistently, growth experiments of mutant strains reveal that AckA1 has a higher capacity for acetate production which allows faster growth in an environment with high acetate concentration. Meanwhile, AckA2 is important for fast acetate-dependent growth at low concentration of acetate. The results demonstrate that the two ACKs have complementary physiological roles in L. lactis to maintain a robust acetate metabolism for fast growth at different extracellular acetate concentrations. The existence of ACK isozymes may reflect a common evolutionary strategy in bacteria in an environment with varying concentrations of acetate. PMID:24638105

  13. Liquid ethylene-propylene copolymers

    NASA Technical Reports Server (NTRS)

    Rhein, R. A.; Ingham, J. D.; Humphrey, M. F.

    1975-01-01

    Oligomers are prepared by heating solid ethylene-propylene rubber in container that retains solid and permits liquid product to flow out as it is formed. Molecular weight and viscosity of liquids can be predetermined by process temperature. Copolymers have low viscosity for given molecular weight.

  14. Polyether-polyester graft copolymer

    NASA Technical Reports Server (NTRS)

    Bell, Vernon L. (Inventor)

    1987-01-01

    Described is a polyether graft polymer having improved solvent resistance and crystalline thermally reversible crosslinks. The copolymer is prepared by a novel process of anionic copolymerization. These polymers exhibit good solvent resistance and are well suited for aircraft parts. Previous aromatic polyethers, also known as polyphenylene oxides, have certain deficiencies which detract from their usefulness. These commercial polymers are often soluble in common solvents including the halocarbon and aromatic hydrocarbon types of paint thinners and removers. This limitation prevents the use of these polyethers in structural articles requiring frequent painting. In addition, the most popular commercially available polyether is a very high melting plastic. This makes it considerably more difficult to fabricate finished parts from this material. These problems are solved by providing an aromatic polyether graft copolymer with improved solvent resistance and crystalline thermally reversible crosslinks. The graft copolymer is formed by converting the carboxyl groups of a carboxylated polyphenylene oxide polymer to ionic carbonyl groups in a suitable solvent, reacting pivalolactone with the dissolved polymer, and adding acid to the solution to produce the graft copolymer.

  15. Electrochemical Deposition Of Conductive Copolymers

    NASA Technical Reports Server (NTRS)

    Nagasubramanian, Ganesan; Distefano, Salvador; Liang, Ranty H.

    1991-01-01

    Experiments show electrically conductive films are deposited on glassy carbon or indium tin oxide substrates by electrochemical polymerization of N-{(3-trimethoxy silyl) propyl} pyrrole or copolymerization with pyrrole. Copolymers of monomer I and pyrrole exhibit desired electrical conductivity as well as desired adhesion and other mechanical properties. When fully developed, new copolymerization process useful in making surface films of selectable conductivity.

  16. Health and Safety Benefits of Small Pressurized Suitport Rovers as EVA Surface Support Vehicles

    NASA Technical Reports Server (NTRS)

    Gernhardt, Michael L.; Abercromby, Andrew F. J.

    2008-01-01

    Pressurized safe-haven providing SPE protection and decompression sickness (DCS) treatment capabilities within 20 mins at all times. Up to 50% reduction in time spent in EVA suits (vs. Unpressurized Rovers) for equal or greater Boots-on-Surface EVA exploration time. Reduces suit-induced trauma and provides improved options for nutrition, hydration, and waste-management. Time spent inside SPR during long translations may be spent performing resistive and cardiovascular exercise. Multiple shorter EVAs versus single 8 hr EVAs increases DCS safety and decreases prebreathe requirements. SPRs also offer many potential operational, engineering and exploration benefits not addressed here.

  17. Ethylene vinyl acetate polymer as a tool for passive sampling monitoring of hydrophobic chemicals in the salmon farm industry.

    PubMed

    Tucca, Felipe; Moya, Heriberto; Barra, Ricardo

    2014-11-15

    Current monitoring programs are focused on hydrophobic chemicals detection in aquatic systems, which require the collection of high volumes of water samples at a given time. The present study documents the preliminary use of the polymer ethylene vinyl acetate (EVA) as a passive sampler for the detection of a hydrophobic chemical used by salmon industries such as cypermethrin. Initially, an experimental calibration in laboratory was performed to determine the cypermethrin equilibrium between sampler and aquatic medium, which was reached after seven days of exposure. A logarithm of partitioning coefficient EVA-water (logKEVA-W) of 5.6 was reported. Field deployment of EVA samplers demonstrated average concentrations of cypermethrin in water to be 2.07 ± 0.7 ng L(-)(1) close to salmon cages, while near-shore was 4.39 ± 0.8 ng L(-)(1). This was a first approach for assessing EVA samplers design as a tool of monitoring in water for areas with salmon farming activity.

  18. Tunable shape memory behaviors of poly(ethylene vinyl acetate) achieved by adding poly(L-lactide)

    NASA Astrophysics Data System (ADS)

    Zhang, Zhi-xing; Liao, Fei; He, Zhen-zhen; Yang, Jing-hui; Huang, Ting; Zhang, Nan; Wang, Yong; Gao, Xiao-ling

    2015-12-01

    In this work, different contents of poly(L-lactide) (PLLA) (20-50 wt%) were introduced into poly(ethylene vinyl acetate) (EVA) to prepare the samples with a tunable shape memory behavior. Morphological characterization demonstrated that with increasing PLLA content from 20 to 50 wt%, the blend morphology changed from sea-island structure to cocontinuous structure. In all the samples, PLLA was amorphous and it did not affect the crystallization of polyethylene part in the EVA component. The presence of PLLA greatly enhanced the storage modulus of samples, especially at relatively low temperatures. The shape memory behaviors of samples were systematically investigated and the results demonstrated that the EVA/PLLA blends exhibited a tunable shape memory effect. On one hand, PLLA accelerated the shape fixation and enhanced the fixity ratio of samples. On the other hand, PLLA reduced the dependence of shape fixity of samples on fixity temperatures. Specifically, for the first time, a critical recovery temperature was observed for the immiscible shape memory polymer blends. In this work, the critical recovery temperature was about 53 °C. At recovery temperature below the critical value, the blends exhibited smaller recovery ratios compared with the pure EVA, however, at recovery temperature above 53 °C, the blends exhibited higher recovery ratios.

  19. The effects of 60Co γ-ray on poly(ethylene-co-vinyl acetate)/carbon black composites

    NASA Astrophysics Data System (ADS)

    Lee, Kyoung-Yong; Kim, Ki-Yup

    2008-04-01

    Cables used in a nuclear power plant are irradiation suppressing ones. Until now, researches on the irradiation suppressing cables have mainly been focused on insulation materials. Therefore, in this paper, the non-isothermal crystallization behaviors and degradation characteristics of ethylene vinyl acetate-carbon black (EVA-CB), used as a shielding material, were investigated by means of the Differential scanning calorimetry (DSC) and chemiluminescence analyzer (CL). The specimens were cooled after removing thermal history at 150 °C for 5 min by changing the cooling rates to 5, 7.5, 10, 15 and 20 °C/min with DSC. In addition, after maintaining a thermal equilibrium at each temperature of 25, 50, 75, 100, 125, 150 and 175 °C, their thermoluminescence was measured for 20 min with CL equipment. The 60Co γ-ray was used for irradiation. Tc, T0, T∞ and t1/2 in the DSC experiments are found to decrease gradually as radiation dose increases. Secondly, with the CL experiment, the 0.1, 0.25 and 0.5 MGy EVA-CB composites were found to show a much smaller thermoluminescence than the intact EVA-CB composites, while the 0.75 and 1 MGy EVA-CB composites were found to show a much higher thermoluminescence than ones.

  20. Kallolide A acetate pyrazoline.

    PubMed

    Rodríguez-Escudero, Idaliz; Marrero, Jeffrey; Rodríguez, Abimael D

    2012-01-01

    IN THE CRYSTAL STRUCTURE OF KALLOLIDE A ACETATE PYRAZOLINE [SYSTEMATIC NAME: 7-methyl-16-oxo-4,10-bis-(prop-1-en-2-yl)-17,18-dioxa-14,15-diaza-tetra-cyclo-[9.4.2.1(6,9).0(1,12)]octa-deca-6,8,14-trien-5-yl acetate], C(23)H(28)N(2)O(5), there is a 12-member-ed carbon macrocyclic structure. In addition, there is a tris-ubstituted furan ring, an approximately planar γ-lactone ring [maximum deviation of 0.057 (3) Å] and a pyraz-oline ring, the latter in an envelope conformation. The pyrazoline and the γ-lactone rings are fused in a cis configuration. In the crystal, mol-ecules are linked by weak C-H⋯O inter-actions, forming a two-dimensional network parallel to (001). An intra-molecular C-H⋯O hydrogen bond is also present.

  1. Kallolide A acetate pyrazoline

    PubMed Central

    Rodríguez-Escudero, Idaliz; Marrero, Jeffrey; Rodríguez, Abimael D.

    2012-01-01

    In the crystal structure of kallolide A acetate pyrazoline [systematic name: 7-methyl-16-oxo-4,10-bis­(prop-1-en-2-yl)-17,18-dioxa-14,15-diaza­tetra­cyclo­[9.4.2.16,9.01,12]octa­deca-6,8,14-trien-5-yl acetate], C23H28N2O5, there is a 12-member­ed carbon macrocyclic structure. In addition, there is a tris­ubstituted furan ring, an approximately planar γ-lactone ring [maximum deviation of 0.057 (3) Å] and a pyraz­oline ring, the latter in an envelope conformation. The pyrazoline and the γ-lactone rings are fused in a cis configuration. In the crystal, mol­ecules are linked by weak C—H⋯O inter­actions, forming a two-dimensional network parallel to (001). An intra­molecular C—H⋯O hydrogen bond is also present. PMID:22259545

  2. Impacts of Repeat Unit Structure and Copolymer Architecture on Thermal and Solution Properties in Homopolymers, Copolymers, and Copolymer Blends

    NASA Astrophysics Data System (ADS)

    Marrou, Stephen Raye

    Gradient copolymers are a relatively new type of copolymer architecture in which the distribution of comonomers gradually varies over the length of the copolymer chain, resulting in a number of unusual properties derived from the arrangement of repeat units. For example, nanophase-segregated gradient copolymers exhibit extremely broad glass transition temperatures (Tgs) resulting from the wide range of compositions present in the nanostructure. This dissertation presents a number of studies on how repeat unit structure and copolymer architecture dictate bulk and solution properties, specifically taking inspiration from the gradient copolymer architecture and comparing the response from this compositionally heterogeneous material to other more conventional materials. The glass transition behavior of a range of common homopolymers was studied to determine the effects of subunit structure on Tg breadth, observing a significant increase in T g breadth with increasing side chain length in methacrylate-based homopolymers and random copolymers. Additionally, increasing the composition distribution of copolymers, either by blending individual random copolymers of different overall composition or synthesizing random copolymers to high conversion, resulted in significant increases to Tg breadth. Plasticization of homopolymers and random copolymers with low molecular weight additives also served to increase the Tg breadth; the most dramatic effect was observed in the selective plasticization of a styrene/4-vinylpyridine gradient copolymer with increases in T g breadth to values above 100 °C. In addition, the effects of repeat unit structure and copolymer architecture on other polymer properties besides Tg were also investigated. The intrinsic fluorescence of styrene units in styrene-containing copolymers was studied, noting the impact of repeat unit structure and copolymer architecture on the resulting fluorescence spectra in solution. The impact of repeat unit structure on

  3. Block copolymers of the type poly(caprolactone)-b-poly(ethylene oxide) for the preparation and stabilization of nanoemulsions.

    PubMed

    Chausson, Mickael; Fluchère, Ann-Sophie; Landreau, Emmanuel; Aguni, Youssef; Chevalier, Yves; Hamaide, Thierry; Abdul-Malak, Nabil; Bonnet, Isabelle

    2008-10-01

    Block copolymers poly(caprolactone)-block-poly(ethylene oxide) are promising non-ionic macromolecular surfactants for the stabilization of emulsions because they display a stronger adsorption and provide an increased long-term stability. But such amphiphilic copolymers should also allow the fabrication of the suspensions according to the emulsification process used. An evaluation of such block copolymers was done regarding the nanoprecipitation and the miniemulsion polymerization processes that both afford aqueous suspensions of nanoparticles. Both the fabrication and the long-term stability were investigated. It was found that the emulsification by means of the nanoprecipitation process was successful when the amphiphilic block copolymer was added into the organic phase. The studies on the structure-activity relationships have shown that a minimum length of the poly(ethylene oxide) block was necessary in order to ensure both the long-term colloidal stability of the suspensions and the instantaneous stability during the preparation process. The length of the hydrophobic block was a parameter of less relevance, but a minimum length was required for the copolymers to be soluble in the organic phase. The miniemulsion polymerization process using block copolymer emulsifiers could be adapted to the incorporation of large loads of vitamin E acetate used as a hydrophobe stabilizer.

  4. Ethylene vinyl acetate based radiation grafted hydrophilic matrices: Process parameter standardization, grafting kinetics and characterization

    NASA Astrophysics Data System (ADS)

    Chaudhari, C. V.; Mondal, R. K.; Dubey, K. A.; Grover, V.; Panicker, L.; Bhardwaj, Y. K.; Varshney, L.

    2016-08-01

    A transparent, elastomeric, grafted matrix for several potential applications was synthesized by single-step simultaneous radiation grafting of methacrylic acid onto ethylene vinyl acetate (EVA). CuSO4 was found to be the most suitable homo-polymerization inhibitor among different inhibitors tried. The grafting kinetics was found to be a strong function of dose rate (D) and monomer content (M) and an equation relating grafting rate Rg=Kg [M]1.13D0.23 was deduced. Crystallinity of the grafted matrices as assessed from XRD and DSC measurements indicated decrease in crystalline content with increase in grafting yield, suggesting crystalline domain of EVA get disrupted on grafting. Elastic modulus increased linearly with the increase in grafting yield, though elongation at break decreased precipitously from 900% to 30% at even ~9% grafting. Thermo-gravimetric analysis showed three step weight loss of the grafted EVA matrix. The grafting of MAA resulted in increase in surface energy mainly due to enhanced polar component.

  5. Long-term survival of salivary streptococci on dental devices made of ethylene vinyl acetate

    PubMed Central

    Ogawa, Taiji; Yamasaki, Sayaka; Honda, Mariko; Terao, Yutaka; Kawabata, Shigetada; Maeda, Yoshinobu

    2012-01-01

    Bacterial infection associated with the use of medical or dental devices is a serious concern. Although devices made of ethylene vinyl acetate (EVA) are often used in the oral cavity, there are no established standards for their storage. We investigated bacterial survival on EVA sheets under various storage conditions to establish a standard for hygienic storage of such dental devices. Bacterial counts were evaluated, which showed a significant decrease after washing with sterilized water, mechanical brushing and rinsing, and using Mouthguard Cleaner as compared to untreated samples. In addition, no bacteria were detected on samples stored 2 days or longer in a ventilated environment, whereas they were detected for up to 14 days on samples without any cleaning stored in a closed environment. Bacterial counts for the untreated samples gradually declined, while surviving bacteria on samples treated with sterilized water and mechanical brushing showed a rapid decrease. Additionally, bacterial identification using polymerase chain reaction (PCR) revealed that Streptococcus oralis was dominantly detected on salivary samples after 14 days of storage among both two subjects. For effective hygienic storage of dental devices made of EVA, washing with sterilized water is important to remove absorbed salivary compounds along with storage in a ventilated environment. PMID:22422084

  6. Hubble Space Telescope EVA Power Ratchet Tool redesign

    NASA Astrophysics Data System (ADS)

    Richards, Paul W.; Park, Chan; Brown, Lee

    The Power Ratchet Tool (PRT) is a self contained, power-driven, 3/8 inch drive ratchet wrench which will be used by astronauts during Extravehicular Activities (EVA). This battery-powered tool is controlled by a dedicated electonic controller. The PRT was flown during the Hubble Space Telescope (HST) Deployment Mission STS-31 to deploy the solar arrays if the automatic mechanisms failed. The PRT is currently intended for use during the first HST Servicing Mission STS-61 as a general purpose power tool. The PRT consists of three major components; the wrench, the controller, and the battery module. Fourteen discrete combinations of torque, turns, and speed may be programmed into the controller before the EVA. The crewmember selects the desired parameter profile by a switch mounted on the controller. The tool may also be used in the manual mode as a non-powered ratchet wrench. The power is provided by a silver-zinc battery module, which fits into the controller and is replaceable during an EVA. The original PRT did not meet the design specification of torque output and hours of operation. To increase efficiency and reliability the PRT underwent a redesign effort. The majority of this effort focused on the wrench. The original PRT drive train consisted of a low torque, high speed brushless DC motor, a face gear set, and a planocentric gear assembly. The total gear reduction was 300:1. The new PRT wrench consists of a low speed, high torque brushless DC motor, two planetary gear sets and a bevel gear set. The total gear reduction is now 75:1. A spline clutch has also been added to disengage the drive train in the manual mode. The design changes to the controller will consist of only those modifications necessary to accomodate the redesigned wrench.

  7. Techniques for Improving the Performance of Future EVA Maneuvering Systems

    NASA Technical Reports Server (NTRS)

    Williams, Trevor W.

    1995-01-01

    The Simplified Aid for EVA Rescue (SAFER) is a small propulsive backpack that was developed as an in-house effort at Johnson Space Center; it is a lightweight system which attaches to the underside of the Primary Life Support Subsystem (PLSS) backpack of the Extravehicular Mobility Unit (EMU). SAFER provides full six-axis control, as well as Automatic Attitude Hold (AAH), by means of a set of cold-gas nitrogen thrusters and a rate sensor-based control system. For compactness, a single hand controller is used, together with mode switching, to command all six axes. SAFER was successfully test-flown on the STS-64 mission in September 1994 as a Development Test Objective (DTO); development of an operational version is now proceeding. This version will be available for EVA self-rescue on the International Space Station and Mir, starting with the STS-86/Mir-7 mission in September 1997. The DTO SAFER was heavily instrumented, and produced in-flight data that was stored in a 12 MB computer memory on-board. This has allowed post-flight analysis to yield good estimates for the actual mass properties (moments and products of inertia and center of mass location) encountered on-orbit. By contrast, Manned Maneuvering Unit (MMU) post-flight results were generated mainly from analysis of video images, and so were not very accurate. The main goal of the research reported here was to use the detailed SAFER on-orbit mass properties data to optimize the design of future EVA maneuvering systems, with the aim being to improve flying qualities and/or reduce propellant consumption. The Automation, Robotics and Simulation Division Virtual Reality (VR) Laboratory proved to be a valuable research tool for such studies. A second objective of the grant was to generate an accurate dynamics model in support of the reflight of the DTO SAFER on STS-76/Mir-3. One complicating factor was the fact that a hand controller stowage box was added to the underside of SAFER on this flight; the position of

  8. Astronaut Harrison Schmitt collects lunar rake samples during EVA

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Scientist-Astronaut Harrison H. Schmitt collects lunar rake samples at Station 1 during the first Apollo 17 extravehicular activity (EVA-1) at the Taurus-Littrow landing site. This picture was taken by Astronatu Eugene Cernan, Apollo 17 commander. Schmitt is the lunar module pilot. The lunar rake, An Apollo lunar geology hand tool, is used to collect discrete samples of rocks and rock chips ranging in size from one-half inch (1.3 cm) to one inch (2.5 cm).

  9. Astronaut Harrison Schmitt collects lunar rake samples during EVA

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Scientist-Astronaut Harrison H. Schmitt collects lunar rake samples at Station 1 during the first Apollo 17 extravehicular activity (EVA-1) at the Taurus-Littrow landing site. This picture was taken by Astronaut Eugene Cernan, Apollo 17 commander. Schmitt is the lunar module pilot. The lunar rake, an Apollo lunar geology hand tool, is used to collect discrete samples of rocks and rock chips ranging in size from one-half inch (1.3 cm) to one inch (2.5 cm).

  10. Baseline tests of the EVA contractor electric passenger vehicle

    NASA Technical Reports Server (NTRS)

    Bozek, J. M.; Tryon, H. B.; Slavick, R. J.

    1977-01-01

    The EVA Contactor four door sedan, an electric passenger vehicle, was tested to characterize the state-of-the-art of electric vehicles. It is a four passenger sedan that was converted to an electric vehicle. It is powered by 16 series connected 6 volt electric vehicle batteries through a four step contactor controller actuated by a foot accelerator pedal. The controller changes the voltage applied to the separately excited DC motor. The braking system is a vacuum assisted hydraulic braking system. Regenerative braking was also provided.

  11. Boudreaux the Robot (a.k.a. EVA Robotic Assistant)

    NASA Technical Reports Server (NTRS)

    Shillcutt, Kimberly; Burridge, Robert; Graham, Jeffrey

    2002-01-01

    The EVA Robotic Assistant is a prototype for an autonomous rover designed to assist human astronauts. The primary focus of the research is to explore the interaction between humans and robots, particularly in extreme environments, and to develop a software infrastructure that could be applied to any type of assistant robot, whether for planetary exploration or orbital missions. This paper describes the background and current status of the project, the types of scenarios addressed in field demonstrations, the hardware and software that comprise the current prototype, and future research plans.

  12. Astronaut Thomas Mattingly performs EVA during Apollo 16 transearth coast

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Astronaut Thomas K. Mattingly II, command module pilot of the Apollo 16 lunar landing mission, performs extravehicular activity (EVA) during the Apollo 16 transearth coast. mattingly is assisted by Astronaut Charles M. Duke Jr., lunar module pilot. Mattingly inspected the SIM bay of the Service Module, and retrieved film from the Mapping and Panoramic cameras. Mattingly is wearing the helmet of Astronaut John W. Young, commander. The helmet's lunar extravehicular visor assembly helped protect Mattingly's eyes frmo the bright sun. This view is a frame from motion picture film exposed by a 16mm Maurer camera.

  13. Apollo 16 lunar module 'Orion' photographed from distance during EVA

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The Apollo 16 Lunar Module 'Orion' is photographed from a distance by Astronaut Chares M. Duke Jr., lunar module pilot, aboard the moving Lunar Roving Vehicle. Astronauts Duke and John W. Young, commander, were returning from the excursion to Stone Mountain during the second Apollo 16 extravehicular activity (EVA-2). The RCA color television camera mounted on the LRV is in the foreground. A portion of the LRV's high-gain antenna is at top left. Smoky Mountain rises behind the LM in this north-looking view at the Descartes landing site.

  14. STS-118 Astronauts Rick Mastracchio and Clay Anderson Perform EVA

    NASA Technical Reports Server (NTRS)

    2007-01-01

    As the construction continued on the International Space Station (ISS), STS-118 astronaut and mission specialist Rick Mastracchio was anchored on the foot restraint of the Canadarm2 as he participated in the third session of Extra Vehicular Activity (EVA) for the mission. Assisting Mastracchio was Expedition 15 flight engineer Clay Anderson (out of frame). During the 5 hour, 28 minute space walk, the two relocated the S-band Antenna Sub-Assembly from the Port 6 (P6) truss to the Port 1 (P1) truss, installed a new transponder on P1 and retrieved the P6 transponder.

  15. Extravehicular Activity (EVA) Power, Avionics, and Software (PAS) 101

    NASA Technical Reports Server (NTRS)

    Irimies, David

    2011-01-01

    EVA systems consist of a spacesuit or garment, a PLSS, a PAS system, and spacesuit interface hardware. The PAS system is responsible for providing power for the suit, communication of several types of data between the suit and other mission assets, avionics hardware to perform numerous data display and processing functions, and information systems that provide crewmembers data to perform their tasks with more autonomy and efficiency. Irimies discussed how technology development efforts have advanced the state-of-the-art in these areas and shared technology development challenges.

  16. Separation of statistical poly[(N-vinyl pyrrolidone)-co-(vinyl acetate)]s by reversed-phase gradient liquid chromatography.

    PubMed

    Cheng, Guanglou; Cullen, Jim; Wu, Chi-san

    2011-01-14

    Although size exclusion chromatography (SEC) has been used successfully to determine the molecular weight distribution (MWD) of statistical poly[(N-vinyl pyrrolidone)-co-(vinyl acetate)]s [PVPVAs], SEC cannot separate the copolymers according to their chemical composition. In this article, the separation of commercial PVPVAs with varying chemical compositions is reported, by aqueous reversed-phase gradient liquid chromatography (RPLC) using polystyrene-divinylbenzene-based wide pore columns. RPLC-SEC cross-fractionation indicates the presence of molar mass dependant effects during RPLC separation due to broad MWD for the copolymer studied; therefore the width of the RPLC peak could not be associated entirely with chemical composition distribution of the copolymer. Coupling of RPLC with online FTIR spectroscopy reveals the increase of VA content with increasing THF gradient, an indication of interaction mechanism between VA repeating units and the stationary phase for water soluble PVPVAs. Separation of water insoluble PVPVAs and PVAs by the RPLC are possibly based on both interaction and precipitation/redissolution mechanisms.

  17. Bioinspired catecholic copolymers for antifouling surface coatings.

    PubMed

    Cho, Joon Hee; Shanmuganathan, Kadhiravan; Ellison, Christopher J

    2013-05-01

    We report here a synthetic approach to prepare poly(methyl methacrylate)-polydopamine diblock (PMMA-PDA) and triblock (PDA-PMMA-PDA) copolymers combining mussel-inspired catecholic oxidative chemistry and atom transfer radical polymerization (ATRP). These copolymers display very good solubility in a range of organic solvents and also a broad band photo absorbance that increases with increasing PDA content in the copolymer. Spin-cast thin films of the copolymer were stable in water and showed a sharp reduction (by up to 50%) in protein adsorption compared to those of neat PMMA. Also the peak decomposition temperature of the copolymers was up to 43°C higher than neat PMMA. The enhanced solvent processability, thermal stability and low protein adsorption characteristics of this copolymer makes it attractive for variety of applications including antifouling coatings on large surfaces such as ship hulls, buoys, and wave energy converters.

  18. Generic extravehicular (EVA) and telerobot task primitives for analysis, design, and integration. Version 1.0: Reference compilation for the EVA and telerobotics communities

    NASA Technical Reports Server (NTRS)

    Smith, Jeffrey H.; Drews, Michael

    1990-01-01

    The results are described of an effort to establish commonality and standardization of generic crew extravehicular (crew-EVA) and telerobotic task analysis primitives used for the study of spaceborne operations. Although direct crew-EVA plans are the most visible output of spaceborne operations, significant ongoing efforts by a wide variety of projects and organizations also require tools for estimation of crew-EVA and telerobotic times. Task analysis tools provide estimates for input to technical and cost tradeoff studies. A workshop was convened to identify the issues and needs to establish a common language and syntax for task analysis primitives. In addition, the importance of such a syntax was shown to have precedence over the level to which such a syntax is applied. The syntax, lists of crew-EVA and telerobotic primitives, and the data base in diskette form are presented.

  19. Underwater EVA training in the WETF with astronaut Robert L. Stewart

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Underwater extravehicular activity (EVA) training in the weightless environment training facility (WETF) with astronaut Robert L. Stewart. Stewart is simulating a planned EVA using the mobile foot restraint device and a one-G version of the Canadian-built remote manipulator system.

  20. An Experimental Investigation of Dextrous Robots Using EVA Tools and Interfaces

    NASA Technical Reports Server (NTRS)

    Ambrose, Robert; Culbert, Christopher; Rehnmark, Frederik

    2001-01-01

    This investigation of robot capabilities with extravehicular activity (EVA) equipment looks at how improvements in dexterity are enabling robots to perform tasks once thought to be beyond machines. The approach is qualitative, using the Robonaut system at the Johnson Space Center (JSC), performing task trials that offer a quick look at this system's high degree of dexterity and the demands of EVA. Specific EVA tools attempted include tether hooks, power torque tools, and rock scoops, as well as conventional tools like scissors, wire strippers, forceps, and wrenches. More complex EVA equipment was also studied, with more complete tasks that mix tools, EVA hand rails, tethers, tools boxes, PIP pins, and EVA electrical connectors. These task trials have been ongoing over an 18 month period, as the Robonaut system evolved to its current 43 degree of freedom (DOF) configuration, soon to expand to over 50. In each case, the number of teleoperators is reported, with rough numbers of attempts and their experience level, with a subjective difficulty rating assigned to each piece of EVA equipment and function. JSC' s Robonaut system was successful with all attempted EVA hardware, suggesting new options for human and robot teams working together in space.

  1. Crystalline Imide/Arylene Ether Copolymers

    NASA Technical Reports Server (NTRS)

    Jensen, Brian J.; Hergenrother, Paul M.; Bass, Robert G.

    1991-01-01

    Series of imide/arylene ether block copolymers prepared by using arylene ether blocks to impart low melt viscosity, and imide blocks to provide high strength and other desirable mechanical properties. Work represents extension of LAR-14159 on imide/arylene ether copolymers in form of films, moldings, adhesives, and composite matrices. Copolymers potentially useful in variety of high-temperature aerospace and microelectronic applications.

  2. Copolymers of fluorinated polydienes and sulfonated polystyrene

    DOEpatents

    Mays, Jimmy W.; Gido, Samuel P.; Huang, Tianzi; Hong, Kunlun

    2009-11-17

    Copolymers of fluorinated polydienes and sulfonated polystyrene and their use in fuel cell membranes, batteries, breathable chemical-biological protective materials, and templates for sol-gel polymerization.

  3. Self-assembly of Random Copolymers

    PubMed Central

    Li, Longyu; Raghupathi, Kishore; Song, Cunfeng; Prasad, Priyaa; Thayumanavan, S.

    2014-01-01

    Self-assembly of random copolymers has attracted considerable attention recently. In this feature article, we highlight the use of random copolymers to prepare nanostructures with different morphologies and to prepare nanomaterials that are responsive to single or multiple stimuli. The synthesis of single-chain nanoparticles and their potential applications from random copolymers are also discussed in some detail. We aim to draw more attention to these easily accessible copolymers, which are likely to play an important role in translational polymer research. PMID:25036552

  4. Enhanced Adhesion of EVA Laminates to Primed Glass Substrates Subjected to Damp-Heat Exposure

    SciTech Connect

    Pern, F. J.; Jorgensen, G. J.

    2005-02-01

    We investigated the effectiveness of glass-surface priming to promote enhanced adhesion of EVA laminates during damp-heat exposure at 85 C and 85% relative humidity. The primary objective was to develop advanced encapsulant formulations by incorporation of various primer formulations that exhibit improved adhesion during damp-heat exposure. Several primer formulations were identified that greatly enhanced the EVA adhesion strength, including to the extent that peeling could not be initiated, even for the laminates of the glass substrate/fast-cure EVA15295P/TPE backsheet (a Tedlar/polyester/EVA tri-laminate) that were exposed in a damp-heat test chamber for more than 750 h. The results show that a synergistic increase in the interfacial hydrophobicity, siloxane density, and cross-linking density are the key attributes to the improvement in the EVA adhesion strength.

  5. Space Station Freedom airlock - The integration of IVA and EVA capabilities in an orbital element

    NASA Astrophysics Data System (ADS)

    Moore, Thomas O., Jr.; Matthews, Anthony P.

    1992-07-01

    In order to meet mission goals, the Space Station Freedom (SSF) airlock must maximize crew efficiency while supporting a range of extravehicular activity (EVA) and intravehicular activity (IVA) operations. EVA will be a frequently planned occurrence on SSF. In order to maximize the usefulness of the limited EVA resource, overhead times must be minimized. This paper discusses how the SSF airlock outfitting design responds to both IVA and EVA requirements. An overview of the SSF airlock and the missions it must accomplish are also provided. The focus of this paper is on how the outfitting and man systems designs provide solutions to multiple requirements, explicitly stated as well as derived requirements. The Space Station airlock is evaluated as an integrated system in the functional assessments of the EVA task, and this paper explains how station common hardware and systems are adapted to the unique airlock environment.

  6. High Performance EVA Glove Collaboration: Glove Injury Data Mining Effort

    NASA Technical Reports Server (NTRS)

    Reid, C. R.; Benosn, E.; England, S.; Norcross, J. R.; McFarland, S. M.; Rajulu, S.

    2014-01-01

    Human hands play a significant role during extravehicular activity (EVA) missions and Neutral Buoyancy Lab (NBL) training events, as they are needed for translating and performing tasks in the weightless environment. It is because of this high frequency usage that hand- and arm-related injuries and discomfort are known to occur during training in the NBL and while conducting EVAs. Hand-related injuries and discomforts have been occurring to crewmembers since the days of Apollo. While there have been numerous engineering changes to the glove design, hand-related issues still persist. The primary objectives of this study are therefore to: 1) document all known EVA glove-related injuries and the circumstances of these incidents, 2) determine likely risk factors, and 3) recommend ergonomic mitigations or design strategies that can be implemented in the current and future glove designs. METHODS: The investigator team conducted an initial set of literature reviews, data mining of Lifetime Surveillance of Astronaut Health (LSAH) databases, and data distribution analyses to understand the ergonomic issues related to glove-related injuries and discomforts. The investigation focused on the injuries and discomforts of U.S. crewmembers who had worn pressurized suits and experienced glove-related incidents during the 1980 to 2010 time frame, either during training or on-orbit EVA. In addition to data mining of the LSAH database, the other objective of the study was to find complimentary sources of information such as training experience, EVA experience, suit-related sizing data, and hand-arm anthropometric data to be tied to the injury data from LSAH. RESULTS: Past studies indicated that the hand was the most frequently injured part of the body during both EVA and NBL training. This study effort thus focused primarily on crew training data in the NBL between 2002 and 2010. Of the 87 recorded training incidents, 19 occurred to women and 68 to men. While crew ages ranged from

  7. Initial Work Toward a Robotically Assisted EVA Glove

    NASA Technical Reports Server (NTRS)

    Rogers, J.; Peters, B.; McBryan, E.; Laske, E.

    2016-01-01

    The Space Suit RoboGlove is a device designed to provide additional grasp strength or endurance for an EVA crew member since gloved hand performance is a fraction of what the unencumbered human hand can achieve. There have been past efforts to approach this problem by employing novel materials and construction techniques to the glove design, as well as integrating powered assistance devices. This application of the NASA/GM RoboGlove technology uses a unique approach to integrate the robotic actuators and sensors into a Phase VI EVA glove. This design provides grasp augmentation to the glove user while active, but can also function as a normal glove when disabled. Care was taken to avoid adding excessive bulk to the glove or affecting tactility by choosing low-profile sensors and extrinsically locating the actuators. Conduits are used to guide robotic tendons from linear actuators, across the wrist, and to the fingers. The second generation of the SSRG includes updated electronics, sensors, and actuators to improve performance. The following discusses the electromechanical design, softgoods integration, and control system of the SSRG. It also presents test results from the first integration of a powered mobility element onto a space suit, the NASA Mark III. Early results show that sensor integration did not impact tactile feedback in the glove and the actuators show potential for reduction in grasp fatigue over time.

  8. A new method of measuring the stiffness of astronauts' EVA gloves

    NASA Astrophysics Data System (ADS)

    Mousavi, Mehdi; Appendino, Silvia; Battezzato, Alessandro; Bonanno, Alberto; Chen Chen, Fai; Crepaldi, Marco; Demarchi, Danilo; Favetto, Alain; Pescarmona, Francesco

    2014-04-01

    Hand fatigue is one of the most important problems of astronauts during their missions to space. This fatigue is due to the stiffness of the astronauts' gloves known as Extravehicular Activity (EVA) gloves. The EVA glove has a multilayered, bulky structure and is pressurized against the vacuum of space. In order to evaluate the stiffness of EVA gloves, different methods have been proposed in the past. In particular, the effects of wearing an EVA glove on the performance of the hands have been published by many researchers to represent the stiffness of the EVA glove. In this paper, a new method for measuring the stiffness of EVA gloves is proposed. A tendon-actuated finger probe is designed and used as an alternative to the human index finger in order to be placed inside an EVA glove and measure its stiffness. The finger probe is equipped with accelerometers, which work as tilt sensors, to measure the angles of its phalanges. The phalanges are actuated by applying different amount of torque using the tendons of the finger probe. Moreover, a hypobaric glove box is designed and realized to simulate the actual operating pressure of the EVA glove and to measure its stiffness in both pressurized and non-pressurized conditions. In order to prove the right performance of the proposed finger probe, an Orlam-DM EVA glove is used to perform a number of tests. The equation of stiffness for the PIP joint of this glove is extracted from the results acquired from the tests. This equation presents the torque required to flex the middle phalanx of the glove. Then, the effect of pressurization on the stiffness is highlighted in the last section. This setup can be used to measure the stiffness of different kinds of EVA gloves and allows direct, numerical comparison of their stiffness.

  9. Degradable and comb-like PEG-based copolymers by nitroxide-mediated radical ring-opening polymerization.

    PubMed

    Delplace, Vianney; Tardy, Antoine; Harrisson, Simon; Mura, Simona; Gigmes, Didier; Guillaneuf, Yohann; Nicolas, Julien

    2013-10-14

    Three cyclic ketene acetals, 2-methylene-1,3-dioxepane (MDO), 5,6-benzo-2-methylene-1,3-dioxepane (BMDO), and 2-methylene-4-phenyl-1,3-dioxolane (MPDL), have been copolymerized with oligo(ethylene glycol) methyl ether methacrylate and a small amount of acrylonitrile (or styrene) at 90 °C by nitroxidemediated radical ring-opening polymerization, as a convenient way to prepare degradable PEG-based copolymers for biomedical applications. MPDL was the best candidate, enabling high monomer conversions to be reached and well-defined PEG-based copolymers with adjustable amount of ester groups in the main chain to be synthesized, leading to nearly complete hydrolytic degradation (5% KOH aqueous solution, ambient temperature). The noncytotoxicity of the obtained copolymers was shown on three different cell lines (i.e., fibroblasts, endothelial cells and macrophages), representing a promising approach for the design of degradable precursors for PEGylation and bioconjugation via the NMP technique.

  10. Study of emulsion stabilization by graft copolymers using the optical analyzer Turbiscan.

    PubMed

    Lemarchand, Caroline; Couvreur, Patrick; Vauthier, Christine; Costantini, Dominique; Gref, Ruxandra

    2003-03-18

    Oil-in-water nanoemulsions were prepared using a series of synthetic graft copolymers with a backbone of dextran (DEX) and a number of side chains of poly-epsilon-caprolactone (PCL). In this paper, we focus on the o/w emulsion stabilizing abilities of these novel PCL-DEX copolymers, using a recently developed optical analyzer (Turbiscan). The main advantage of Turbiscan is to detect the destabilization phenomena in non-diluted emulsion, much earlier than the naked eye's operator, especially in the case of an opaque and concentrated system. This study shows that PCL-DEX copolymers successfully stabilized ethyl acetate-in-water emulsions, even in the absence of additional surfactants, whereas they were not efficient in stabilizing methylene chloride-in-water emulsions which coalesced fast and irreversibly. The ethyl acetate-in-water emulsion stabilizing ability of PCL-DEX seemed to be related to the localization of their blocks with regard to the oil-water interface.

  11. Development of block co-polymers as self-assembling templates for patterned media.

    SciTech Connect

    Warke, V.; Bakker, M. G.; Hong, K.; Mays, J.; Britt, P.; Li, X.; Wang, J.; X-Ray Science Division; Univ. of Alabama; ORNL

    2006-01-01

    Block copolymers that self-organize are of interest as templates for patterned media, as they potentially provide a low cost fabrication route. Poly(styrene)-Poly(methylmethacrylate) block co-polymers (PS-b-PMMA) of appropriate block length and PS to PMMA ratio self-assemble into a 2-D hexagonal phase in which the PS majority phase is continuous and surrounds cylinders of the minority, PMMA phase. For application of this phase to patterned media it is necessary that the cylinders of the minority phase be oriented perpendicular to the substrate surface. This can be achieved by a number of methods, including appropriate choice of substrate and use of a random co-polymer underlayer. Appropriate substrates include H-terminated silicon, some carbon coatings and some ITO glasses. Use of an acetic acid wash causes the minority PMMA component can be induced to be rearranged, giving rise to pores perpendicular to the substrate. Electrodeposition of a metal into the pores produces a hardmask which can be used with ion-milling to transfer the block co-polymer pattern onto a magnetic thin film.

  12. Influence of Copolymer Composition on In Vitro and In Vivo Performance of Celecoxib-PVP/VA Amorphous Solid Dispersions.

    PubMed

    Knopp, Matthias Manne; Nguyen, Julia Hoang; Mu, Huiling; Langguth, Peter; Rades, Thomas; Holm, René

    2016-03-01

    Previous studies suggested that an amorphous solid dispersion with a copolymer consisting of both hydrophobic and hydrophilic monomers could improve the dissolution profile of a poorly water-soluble drug compared to the crystalline form. Therefore, this study investigated the influence of the copolymer composition of polyvinylpyrrolidone/vinyl acetate (PVP/VA) on the non-sink in vitro dissolution behavior and in vivo performance of celecoxib (CCX) amorphous solid dispersions. The study showed that the hydrophilic monomer vinylpyrrolidone (VP) was responsible for the generation of CCX supersaturation whereas the hydrophobic monomer vinyl acetate (VA) was responsible for the stabilization of the supersaturated solution. For CCX, there was an optimal copolymer composition around 50-60% VP content where further replacement of VP monomers with VA monomers did not have any biopharmaceutical advantages. A linear relationship was found between the in vitro AUC(0-4h) and in vivo AUC(0-24h) for the CCX:PVP/VA systems, indicating that the non-sink in vitro dissolution method applied in this study was useful in predicting the in vivo performance. These results indicated that when formulating a poorly water-soluble drug as an amorphous solid dispersion using a copolymer, the copolymer composition has a significant influence on the dissolution profile and in vivo performance. Thus, the dissolution profile of a drug can theoretically be tailored by changing the monomer ratio of a copolymer with respect to the required in vivo plasma-concentration profile. As this ratio is likely to be drug dependent, determining the optimal ratio between the hydrophilic (dissolution enhancing) and hydrophobic (crystallization inhibiting) monomers for a given drug is imperative.

  13. Dimensionally Stable Ether-Containing Polyimide Copolymers

    NASA Technical Reports Server (NTRS)

    Fay, Catharine C. (Inventor); St.Clair, Anne K. (Inventor)

    1999-01-01

    Novel polyimide copolymers containing ether linkages were prepared by the reaction of an equimolar amount of dianhydride and a combination of diamines. The polyimide copolymers described herein possess the unique features of low moisture uptake, dimensional stability, good mechanical properties, and moderate glass transition temperatures. These materials have potential application as encapsulants and interlayer dielectrics.

  14. Thermochemical characteristics of chitosan-polylactide copolymers

    NASA Astrophysics Data System (ADS)

    Goruynova, P. E.; Larina, V. N.; Smirnova, N. N.; Tsverova, N. E.; Smirnova, L. A.

    2016-05-01

    The energies of combustion of chitosan and its block-copolymers with different polylactide contents are determined in a static bomb calorimeter. Standard enthalpies of combustion and formation are calculated for these substances. The dependences of the thermochemical characteristics on block-copolymer composition are determined and discussed.

  15. Process-Accessible States of Block Copolymers

    NASA Astrophysics Data System (ADS)

    Sun, De-Wen; Müller, Marcus

    2017-02-01

    Process-directed self-assembly of block copolymers refers to thermodynamic processes that reproducibly direct the kinetics of structure formation from a starting, unstable state into a selected, metastable mesostructure. We investigate the kinetics of self-assembly of linear A C B triblock copolymers after a rapid transformation of the middle C block from B to A . This prototypical process (e.g., photochemical transformation) converts the initial, equilibrium mesophase of the A B B copolymer into a well-defined but unstable, starting state of the A A B copolymer. The spontaneous structure formation that ensues from this unstable state becomes trapped in a metastable mesostructure, and we systematically explore which metastable mesostructures can be fabricated by varying the block copolymer composition of the initial and final states. In addition to the equilibrium mesophases of linear A B diblock copolymers, this diagram of process-accessible states includes 7 metastable periodic mesostructures, inter alia, Schoen's F-RD periodic minimal surface. Generally, we observe that the final, metastable mesostructure of the A A B copolymer possesses the same symmetry as the initial, equilibrium mesophase of the A B B copolymer.

  16. 21 CFR 177.2470 - Polyoxymethylene copolymer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ....2470 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Components of Articles Intended for Repeated Use § 177.2470 Polyoxymethylene copolymer. Polyoxymethylene copolymer identified in this section may be safely used as an article or component of articles intended...

  17. 21 CFR 177.2470 - Polyoxymethylene copolymer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ....2470 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Components of Articles Intended for Repeated Use § 177.2470 Polyoxymethylene copolymer. Polyoxymethylene copolymer identified in this section may be safely used as an article or component of articles intended...

  18. 21 CFR 177.2470 - Polyoxymethylene copolymer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ....2470 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Components of Articles Intended for Repeated Use § 177.2470 Polyoxymethylene copolymer. Polyoxymethylene copolymer identified in this section may be safely used as an article or component of articles intended...

  19. Chiral Block Copolymer Structures for Metamaterial Applications

    DTIC Science & Technology

    2015-01-27

    Final 3. DATES COVERED (From - To) 25-August-2011 to 24-August-2014 4. TITLE AND SUBTITLE Chiral Block Copolymer Structures for...researchers focused o synthesis and processing, morphology and physical characterization of chiral block copolymer (BCP) materials. Such materials a...valuable for both their optical and mechanical properties, particularly for their potential as chiral metamaterials and lightweig energy absorbing

  20. Nanostructured high-performance dielectric block copolymers.

    PubMed

    Liu, Wenmei; Liao, Xiaojuan; Li, Yawei; Zhao, Qiuhua; Xie, Meiran; Sun, Ruyi

    2015-10-25

    A new type of insulating-conductive block copolymer was synthesized by metathesis polymerization. The copolymer can self-assemble into unique nanostructures of micelles or hollow spheres. It exhibits a high dielectric constant, low dielectric loss, and high stored/released energy density due to the strong dipolar and nano-interfacial polarization contributions.

  1. Process-Accessible States of Block Copolymers.

    PubMed

    Sun, De-Wen; Müller, Marcus

    2017-02-10

    Process-directed self-assembly of block copolymers refers to thermodynamic processes that reproducibly direct the kinetics of structure formation from a starting, unstable state into a selected, metastable mesostructure. We investigate the kinetics of self-assembly of linear ACB triblock copolymers after a rapid transformation of the middle C block from B to A. This prototypical process (e.g., photochemical transformation) converts the initial, equilibrium mesophase of the ABB copolymer into a well-defined but unstable, starting state of the AAB copolymer. The spontaneous structure formation that ensues from this unstable state becomes trapped in a metastable mesostructure, and we systematically explore which metastable mesostructures can be fabricated by varying the block copolymer composition of the initial and final states. In addition to the equilibrium mesophases of linear AB diblock copolymers, this diagram of process-accessible states includes 7 metastable periodic mesostructures, inter alia, Schoen's F-RD periodic minimal surface. Generally, we observe that the final, metastable mesostructure of the AAB copolymer possesses the same symmetry as the initial, equilibrium mesophase of the ABB copolymer.

  2. Synthesis and Characterization of Block Copolymers.

    DTIC Science & Technology

    1987-07-01

    Polyether-Polyimide Block Copolymers; Three series of Polyether-Polyimide (PEPI) block copolymers were synthesized. Soft segments were poly( propylene ... glycol ) (PPO) Mn = 2,000 and 4,000. Hard segments were pyromellitic dianhydride (PMDA) and di-(2-hydroxyethyl)-dimethylhydantoin (H). The hard

  3. Responsive copolymers for enhanced petroleum recovery

    SciTech Connect

    McCormick, C.; Hester, R.

    1992-01-01

    The overall goal of this research is the development of advanced water-soluble copolymers for use in enhanced oil recovery which rely on reversible microheterogeneous associations for mobility control and reservoir conformance. Technical progress is summarized for the following tasks: advanced copolymer synthesis; characterization of macromolecular structure and properties; and solution rheology in a porous media.

  4. Imide/arylene ether block copolymers

    NASA Technical Reports Server (NTRS)

    Jensen, B. J.; Hergenrother, P. M.; Bass, R. G.

    1991-01-01

    Two series of imide/arylene either block copolymers were prepared using an arylene ether block and either an amorphous or semi-crystalline imide block. The resulting copolymers were characterized and selected physical and mechanical properties were determined. These results, as well as comparisons to the homopolymer properties, are discussed.

  5. Asteroid Redirect Crewed Mission Space Suit and EVA System Architecture Trade Study

    NASA Technical Reports Server (NTRS)

    Blanco, Raul A.; Bowie, Jonathan T.; Watson, Richard D.; Sipila, Stephanie A.

    2014-01-01

    The Asteroid Redirect Crewed Mission (ARCM) requires a Launch/Entry/Abort (LEA) suit capability and short duration Extra Vehicular Activity (EVA) capability for Orion. The EVAs will involve a two-person crew for approximately four hours. Currently, two EVAs are planned with one contingency EVA in reserve. Providing this EVA capability is very challenging due to system level constraints and a new and unknown environment. The goal of the EVA architecture for ARCM is one that builds upon previously developed technologies and lessons learned, and that accomplishes the ARCM mission while providing a stepping stone to future missions and destinations. The primary system level constraints are to 1) minimize system mass and volume and 2) minimize the interfacing impacts to the baseline Orion design. In order to minimize the interfacing impacts and to not perturb the baseline Orion schedule, the concept of adding "kits" to the baseline system is proposed. These kits consist of: an EVA kit (converts LEA suit to EVA suit), EVA Servicing and Recharge Kit (provides suit consumables), the EVA Tools, Translation Aids & Sample Container Kit (the tools and mobility aids to complete the tasks), the EVA Communications Kit (interface between the EVA radio and the MPCV), and the Cabin Repress Kit (represses the MPCV between EVAs). This paper will focus on the trade space, analysis, and testing regarding the space suit (pressure garment and life support system). Historical approaches and lessons learned from all past EVA operations were researched. Previous and current, successfully operated EVA hardware and high technology readiness level (TRL) hardware were evaluated, and a trade study was conducted for all possible pressure garment and life support options. Testing and analysis was conducted and a recommended EVA system architecture was proposed. Pressure garment options that were considered for this mission include the currently in-use ISS EVA Mobility Unit (EMU), all variations of

  6. 21 CFR 184.1185 - Calcium acetate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    .... No. 62-54-4), also known as acetate of lime or vinegar salts, is the calcium salt of acetic acid. It may be produced by the calcium hydroxide neutralization of acetic acid. (b) The ingredient meets...

  7. 21 CFR 184.1185 - Calcium acetate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    .... No. 62-54-4), also known as acetate of lime or vinegar salts, is the calcium salt of acetic acid. It may be produced by the calcium hydroxide neutralization of acetic acid. (b) The ingredient meets...

  8. 21 CFR 184.1185 - Calcium acetate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    .... No. 62-54-4), also known as acetate of lime or vinegar salts, is the calcium salt of acetic acid. It may be produced by the calcium hydroxide neutralization of acetic acid. (b) The ingredient meets...

  9. 21 CFR 184.1185 - Calcium acetate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... as acetate of lime or vinegar salts, is the calcium salt of acetic acid. It may be produced by the calcium hydroxide neutralization of acetic acid. (b) The ingredient meets the specifications of the...

  10. The main results of EVA medical support on the Mir Space Station.

    PubMed

    Katuntsev, V P; Osipov, Yu Yu; Barer, A S; Gnoevaya, N K; Tarasenkov, G G

    2004-04-01

    The aim of this paper is to review the main results of medical support of 78 two-person extravehicular activities (EVAs) which have been conducted in the Mir Space Program. Thirty-six male crewmembers participated in these EVAs. Maximum length of a space walk was equal to 7 h 14 min. The total duration of all space walks reached 717.1 man-hours. The maximum frequency of EVA's execution was 10 per year. Most of the EVAs (67) have been performed at mission elapsed time ranging from 31 to 180 days. The oxygen atmosphere of the Orlan space suit with a pressure of 40 kPa in combination with the normobaric cabin environment and a short (30 min) oxygen prebreathe protocol have minimized the risk of decompression sickness (DCS). There has been no incidence of DCS during performed EVAs. At the peak activity, metabolic rates and heart rates increased up to 9.9-13 kcal/min and 150-174 min-1, respectively. The medical problems have centred on feeling of moderate overcooling during a rest period in a shadow after the high physical loads, episodes with tachycardia accompanied by cardiac rhythm disorders at the moments of emotional stress, pains in the muscles and general fatigue after the end of a hard EVA. All of the EVAs have been completed safely.

  11. A clinically authentic mouse model of enterovirus 71 (EV-A71)-induced neurogenic pulmonary oedema

    PubMed Central

    Victorio, Carla Bianca Luena; Xu, Yishi; Ng, Qimei; Chua, Beng Hooi; Alonso, Sylvie; Chow, Vincent T. K.; Chua, Kaw Bing

    2016-01-01

    Enterovirus 71 (EV-A71) is a neurotropic virus that sporadically causes fatal neurologic illness among infected children. Animal models of EV-A71 infection exist, but they do not recapitulate in animals the spectrum of disease and pathology observed in fatal human cases. Specifically, neurogenic pulmonary oedema (NPE)—the main cause of EV-A71 infection-related mortality—is not observed in any of these models. This limits their utility in understanding viral pathogenesis of neurologic infections. We report the development of a mouse model of EV-A71 infection displaying NPE in severely affected animals. We inoculated one-week-old BALB/c mice with an adapted EV-A71 strain and identified clinical signs consistent with observations in human cases and other animal models. We also observed respiratory distress in some mice. At necropsy, we found their lungs to be heavier and incompletely collapsed compared to other mice. Serum levels of catecholamines and histopathology of lung and brain tissues of these mice strongly indicated onset of NPE. The localization of virally-induced brain lesions also suggested a potential pathogenic mechanism for EV-A71-induced NPE. This novel mouse model of virally-induced NPE represents a valuable resource for studying viral mechanisms of neuro-pathogenesis and pre-clinical testing of potential therapeutics and prophylactics against EV-A71-related neurologic complications. PMID:27357918

  12. Advanced EVA Capabilities: A Study for NASA's Revolutionary Aerospace Systems Concept Program

    NASA Technical Reports Server (NTRS)

    Hoffman, Stephen J.

    2004-01-01

    This report documents the results of a study carried out as part of NASA s Revolutionary Aerospace Systems Concepts Program examining the future technology needs of extravehicular activities (EVAs). The intent of this study is to produce a comprehensive report that identifies various design concepts for human-related advanced EVA systems necessary to achieve the goals of supporting future space exploration and development customers in free space and on planetary surfaces for space missions in the post-2020 timeframe. The design concepts studied and evaluated are not limited to anthropomorphic space suits, but include a wide range of human-enhancing EVA technologies as well as consideration of coordination and integration with advanced robotics. The goal of the study effort is to establish a baseline technology "road map" that identifies and describes an investment and technical development strategy, including recommendations that will lead to future enhanced synergistic human/robot EVA operations. The eventual use of this study effort is to focus evolving performance capabilities of various EVA system elements toward the goal of providing high performance human operational capabilities for a multitude of future space applications and destinations. The data collected for this study indicate a rich and diverse history of systems that have been developed to perform a variety of EVA tasks, indicating what is possible. However, the data gathered for this study also indicate a paucity of new concepts and technologies for advanced EVA missions - at least any that researchers are willing to discuss in this type of forum.

  13. The main results of EVA medical support on the Mir Space Station

    NASA Astrophysics Data System (ADS)

    Katuntsev, V. P.; Osipov, Yu. Yu.; Barer, A. S.; Gnoevaya, N. K.; Tarasenkov, G. G.

    2004-04-01

    The aim of this paper is to review the main results of medical support of 78 two-person extravehicular activities (EVAs) which have been conducted in the Mir Space Program. Thirty-six male crewmembers participated in these EVAs. Maximum length of a space walk was equal to 7 h 14 min. The total duration of all space walks reached 717.1 man-hours. The maximum frequency of EVA's execution was 10 per year. Most of the EVAs (67) have been performed at mission elapsed time ranging from 31 to 180 days. The oxygen atmosphere of the Orlan space suit with a pressure of 40 kPa in combination with the normobaric cabin environment and a short (30 min) oxygen prebreathe protocol have minimized the risk of decompression sickness (DCS). There has been no incidence of DCS during performed EVAs. At the peak activity, metabolic rates and heart rates increased up to 9.9- 13 kcal/ min and 150- 174 min-1, respectively. The medical problems have centred on feeling of moderate overcooling during a rest period in a shadow after the high physical loads, episodes with tachycardia accompanied by cardiac rhythm disorders at the moments of emotional stress, pains in the muscles and general fatigue after the end of a hard EVA. All of the EVAs have been completed safely.

  14. Pallidol hexa­acetate ethyl acetate monosolvate

    PubMed Central

    Mao, Qinyong; Taylor, Dennis K.; Ng, Seik Weng; Tiekink, Edward R. T.

    2013-01-01

    The entire mol­ecule of pallidol hexa­acetate {systematic name: (±)-(4bR,5R,9bR,10R)-5,10-bis­[4-(acet­yloxy)phen­yl]-4b,5,9b,10-tetra­hydro­indeno­[2,1-a]indene-1,3,6,8-tetrayl tetra­acetate} is completed by the application of twofold rotational symmetry in the title ethyl acetate solvate, C40H34O12·C4H8O2. The ethyl acetate mol­ecule was highly disordered and was treated with the SQUEEZE routine [Spek (2009 ▶). Acta Cryst. D65, 148–155]; the crystallographic data take into account the presence of the solvent. In pallidol hexa­acetate, the dihedral angle between the fused five-membered rings (r.m.s. deviation = 0.100 Å) is 54.73 (6)°, indicating a significant fold in the mol­ecule. Significant twists between residues are also evident as seen in the dihedral angle of 80.70 (5)° between the five-membered ring and the pendent benzene ring to which it is attached. Similarly, the acetate residues are twisted with respect to the benzene ring to which they are attached [C—O(carb­oxy)—C—C torsion angles = −70.24 (14), −114.43 (10) and −72.54 (13)°]. In the crystal, a three-dimensional architecture is sustained by C—H⋯O inter­actions which encompass channels in which the disordered ethyl acetate mol­ecules reside. PMID:24046702

  15. Copolymers of various architectures containing ethylene and 5-norbornen-2-yl derivatives

    NASA Astrophysics Data System (ADS)

    Diamanti, Steve Jon

    Polyolefins are a class of materials with enormous economic impact. Tailoring of polyolefin bulk properties by synthetic control is a major focus of many industrial and academic research groups. Polar functionalities within the hydrophobic polyolefin backbone can change important properties, such as, toughness, adhesion, solvent resistance, blend compatibility with other functional polymers, and rheological properties. Functional polyolefin materials with block or graft architectures are the most desirable structures as the pure polyolefin block maintains its intrinsic properties. Our initial work elucidated a neutral nickel based catalyst system capable of catalyzing the "quasi-living" homopolymerization of ethylene and the "quasi-living" copolymerization of ethylene with 5-norbornen-2-yl acetate (NBA), a polar comonomer. Through testing the effect of several reaction variables on the copolymerization of ethylene with NBA it was found that changing ethylene pressure causes a large change in the content of NBA in the copolymer chain. This change in NBA content, in turn, drastically affects the physical and thermal properties of these polymers. Understanding the impact of such reaction variables on copolymer properties made it possible to design more sophisticated architectures. This catalytic system has since been used to synthesize block copolymers and tapered block copolymers of ethylene and NBA. Block copolymers of ethylene and NBA have been synthesized by a method utilizing ethylene pressure variation to create two distinct copolymeric blocks that are able to order into microphase-separated structures. The block structure of these materials has been proven by 1H-NMR spectroscopy, thermal analysis, GPC, AFM, and TEM. The synthesis, characterization, and bulk and thermal properties of tapered block copolymers containing ethylene and NBA, has also been performed. The final structure of the tapered block polymer is a polar amorphous chain (rich in NBA) on one

  16. CLCA2 Interactor EVA1 Is Required for Mammary Epithelial Cell Differentiation

    PubMed Central

    Ramena, Grace; Yin, Yufang; Yu, Yang; Walia, Vijay; Elble, Randolph C.

    2016-01-01

    CLCA2 is a p53-, p63-inducible transmembrane protein that is frequently downregulated in breast cancer. It is induced during differentiation of human mammary epithelial cells, and its knockdown causes epithelial-to-mesenchymal transition (EMT). To determine how CLCA2 promotes epithelial differentiation, we searched for interactors using membrane dihybrid screening. We discovered a strong interaction with the cell junctional protein EVA1 (Epithelial V-like Antigen 1) and confirmed it by co-immunoprecipitation. Like CLCA2, EVA1 is a type I transmembrane protein that is regulated by p53 and p63. It is thought to mediate homophilic cell-cell adhesion in diverse epithelial tissues. We found that EVA1 is frequently downregulated in breast tumors and breast cancer cell lines, especially those of mesenchymal phenotype. Moreover, knockdown of EVA1 in immortalized human mammary epithelial cells (HMEC) caused EMT, implying that EVA1 is essential for epithelial differentiation. Both EVA1 and CLCA2 co-localized with E-cadherin at cell-cell junctions. The interacting domains were delimited by deletion analysis, revealing the site of interaction to be the transmembrane segment (TMS). The primary sequence of the CLCA2 TMS was found to be conserved in CLCA2 orthologs throughout mammals, suggesting that its interaction with EVA1 co-evolved with the mammary gland. A screen for other junctional interactors revealed that CLCA2 was involved in two different complexes, one with EVA1 and ZO-1, the other with beta catenin. Overexpression of CLCA2 caused downregulation of beta catenin and beta catenin-activated genes. Thus, CLCA2 links a junctional adhesion molecule to cytosolic signaling proteins that modulate proliferation and differentiation. These results may explain how attenuation of CLCA2 causes EMT and why CLCA2 and EVA1 are frequently downregulated in metastatic breast cancer cell lines. PMID:26930581

  17. An air bearing fan for EVA suit ventilation

    NASA Technical Reports Server (NTRS)

    Murry, Roger P.

    1990-01-01

    The portable life-support system (PLSS) ventilation requirements are outlined, along with the application of a high-speed axial fan technology for extravehicular-activity (EVA) space-suit ventilation. Focus is placed on a mechanical design employing high-speed gas bearings, permanent magnet rotor, and current-fed chopper/inverter electronics. The operational characteristics of the fan unit and its applicability for use in a pure-oxygen environment are discussed. It delivers a nominal 0.17 cu m/min at 1.24 kPa pressure rise using 13.8 w of input power. It is shown that the overall selection of materials for all major component meets the NASA requirements.

  18. Further analysis of EVA self-rescue data

    NASA Astrophysics Data System (ADS)

    Brody, Adam R.

    1992-08-01

    Results of an EVA study performed in the Virtual Interactive Environment Workstation at the NASA Ames Research Center are presented. Three initial separation velocities (0.5, 1.0, and 1.5 m/s) were crossed with five initial spin velocities (0, +/-0.1, +/-0.3) to yield 15 different trials. An attitude hold system was also modeled, which, when combined with the 15 combinations of separation and spin velocity, provided 30 distinct trials. Recent examinations of the data reveal that initial separation velocity and initial spin velocity each produced the main effects and combined to produce an interaction effect on the solution time. The solution time increased with the initial velocity and absolute initial spin velocity. The final roll angle also increased the initial spin velocity. The attitude hold fuel increased with absolute initial spin velocity. Interaction effects revealed that the main effects were less pronounced at the lowest initial velocity level.

  19. Architectural development of an advanced EVA Electronic System

    NASA Technical Reports Server (NTRS)

    Lavelle, Joseph

    1992-01-01

    An advanced electronic system for future EVA missions (including zero gravity, the lunar surface, and the surface of Mars) is under research and development within the Advanced Life Support Division at NASA Ames Research Center. As a first step in the development, an optimum system architecture has been derived from an analysis of the projected requirements for these missions. The open, modular architecture centers around a distributed multiprocessing concept where the major subsystems independently process their own I/O functions and communicate over a common bus. Supervision and coordination of the subsystems is handled by an embedded real-time operating system kernel employing multitasking software techniques. A discussion of how the architecture most efficiently meets the electronic system functional requirements, maximizes flexibility for future development and mission applications, and enhances the reliability and serviceability of the system in these remote, hostile environments is included.

  20. STS-114 Astronauts Participate in Extra-Vehicular Activity (EVA)

    NASA Technical Reports Server (NTRS)

    2005-01-01

    Launched on July 26, 2005 from the Kennedy Space Center in Florida, STS-114 was classified as Logistics Flight 1. Among the Station-related activities of the mission were the delivery of new supplies and the replacement of one of the orbital outpost's Control Moment Gyroscopes (CMGs). STS-114 also carried the Raffaello Multi-Purpose Logistics Module (MPLM) and the External Stowage Platform-2. In this photograph, astronaut Soichi Noguchi, STS-114 mission specialist representing the Japan Aerospace Exploration Agency (JAXA), participates in the mission's first scheduled session of Extra-Vehicular Activity (EVA). Noguchi and crew mate Stephen K. Robinson (out of frame) completed a demonstration of Shuttle thermal protection repair techniques and enhancements to the ISS's attitude control system during the successful 6 hour, 50 minute space walk.

  1. Person to Person Biological Heat Bypass During EVA Emergencies

    NASA Technical Reports Server (NTRS)

    Koscheyev, Victor S.; Leon, Gloria R.; Lee, Joo-Young; Kim, Jung-Hyun; Berowiski, Anna; Trevino, Robert C.

    2007-01-01

    During EVA and other extreme environments, mutual human support is sometimes the last way to survive when there is a failure of the life support equipment. The possibility to transfer a coolant to remove heat or a warming fluid to increase heat from one individual to another to support the thermal balance of the individual with system failure was assessed. The following scenarios were considered: 1. one participant has a cooling system that is not working well and already has a body heat deficit equal to 100-120 kcal and a finger temperature decline to 25 C; 2. one participant has the same status of overcooling and the other mild overheating. Preliminary findings showed promise in using such sharing tactics to extend the time duration of survival in extreme situations when there is a high metabolic rate in the donor.

  2. Advanced Design Heat PumpRadiator for EVA Suits

    NASA Technical Reports Server (NTRS)

    Izenson, Michael G.; Chen, Weibo; Passow, Christian; Phillips, Scott; Trevino, Luis

    2009-01-01

    Absorption cooling using a LiCl/water heat pump can enable lightweight and effective thermal control for EVA suits without venting water to the environment. The key components in the system are an absorber/radiator that rejects heat to space and a flexible evaporation cooling garment that absorbs heat from the crew member. This paper describes progress in the design, development, and testing of the absorber/radiator and evaporation cooling garment. New design concepts and fabrication approaches will significantly reduce the mass of the absorber/radiator. We have also identified materials and demonstrated fabrication approaches for production of a flexible evaporation cooling garment. Data from tests of the absorber/radiator s modular components have validated the design models and allowed predictions of the size and weight of a complete system.

  3. Processible Polyaniline Copolymers and Complexes.

    NASA Astrophysics Data System (ADS)

    Liao, Yun-Hsin

    1995-01-01

    Polyaniline (PANI) is an intractable polymer due to the difficulty of melt processing or dissolving it in common solvents. The purpose of the present investigation was to prepare a new class of conducting polyanilines with better solubility both in base and dope forms by (1) adding external salt to break aggregated chains, (2) introducing ring substituted units onto the backbone without disturbing the coplanar structure, and (3) complexing with polymeric dopants to form a soluble polymer complex. Aggregation of PANI chains in dilute solution was investigated in N-methyl-2-pyrrolidinone (NMP) by light scattering, gel permeation chromatography, and viscosity measurements. The aggregation of chains resulted in a negative second virial coefficient in light scattering measurement, a bimodal molecular weight distribution in gel permeation chromatography, and concave reduced viscosity curves. The aggregates can be broken by adding external salt, which resulting in a higher reduced viscosity. The driving force for aggregation is assumed to be a combination of hydrogen bonding between the imine and amine groups, and the rigidity of backbone. The aggregation was modeled to occur via side-on packing of PANI chains. The ring substituted PANI copolymers, poly(aniline -co-phenetidine) were synthesized by chemical oxidation copolymerization using ammonium persulfate as an oxidant. The degree of copolymerization declined with an increasing feed of o-phenetidine in the reaction mixture. The o-phenetidine had a higher reactivity than aniline in copolymerization resulting in a higher content of o-phenetidine in copolymers. The resulting copolymers can be readily dissolved in NMP up to 20% (w/w), and other common solvents, and solutions possess a longer gelation time. The highly soluble copolymer with 20 mole % o-phenetidine in the backbone has same order of conductivity as the unsubstituted PANI after it is doped by HCl. Complexation of PANI and polymeric dopant, poly

  4. Hybridization of Block Copolymer Micelles

    DTIC Science & Technology

    1993-01-01

    J. Macromol. Sci., Part A 1973, 7,601. (10) Tiara, M.; Ramireddy, C.; Webber, S. K; Munk,P. Collect. Czer" (14) 0snford, C. In The Hydrophobic Effect ...equilibrate In the first series of experiments we have studied the within 20 min, similarly as ASA-10 micelles do. However, effect of the copolymer...high. This may happen after a sudden The Johnston-Ogston effect 2’ 6- also may play a role in jump in temperature or in the composition of the mixed

  5. STS-110 Astronaut Jerry Ross Performs Extravehicular Activity (EVA)

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Launched aboard the Space Shuttle Orbiter Atlantis on April 8, 2002, the STS-110 mission prepared the International Space Station (ISS) for future space walks by installing and outfitting the 43-foot-long Starboard side S0 (S-zero) truss and preparing the first railroad in space, the Mobile Transporter. The 27,000 pound S0 truss was the first of 9 segments that will make up the Station's external framework that will eventually stretch 356 feet (109 meters), or approximately the length of a football field. This central truss segment also includes a flatcar called the Mobile Transporter and rails that will become the first 'space railroad,' which will allow the Station's robotic arm to travel up and down the finished truss for future assembly and maintenance. The completed truss structure will hold solar arrays and radiators to provide power and cooling for additional international research laboratories from Japan and Europe that will be attached to the Station. STS-110 Extravehicular Activity (EVA) marked the first use of the Station's robotic arm to maneuver space walkers around the Station and was the first time all of a shuttle crew's space walks were based out of the Station's Quest Airlock. In this photograph, Astronaut Jerry L. Ross, mission specialist, anchored on the end of the Canadarm2, moves near the newly installed S0 truss. Astronaut Lee M. E. Morin, mission specialist, (out of frame), worked in tandem with Ross during this fourth and final scheduled session of EVA for the STS-110 mission. The final major task of the space walk was the installation of a beam, the Airlock Spur, between the Quest Airlock and the S0. The spur will be used by space walkers in the future as a path from the airlock to the truss.

  6. EVA Hazards due to TPS Inspection and Repair

    NASA Technical Reports Server (NTRS)

    Stewart, Christine E.

    2007-01-01

    Tile inspection and repair activities have implicit hazards associated with them. When an Extra Vehicular Activities (EVA) crewmember and associated hardware are added into the equation, additional hazards are introduced. Potential hazards to the Extravehicular Mobility Unit (EMU), the Orbiter or the crew member themselves are created. In order to accurately assess the risk of performing a TPS inspection or repair, an accurate evaluation of potential hazards and how adequately these hazards are controlled is essential. The EMU could become damaged due to sharp edges, protrusions, thermal extremes, molten metal or impact with the Orbiter. Tools, tethers and the presence of a crew member in the vicinity of the Orbiter Thermal Protection System (TPS) pose hazards to the Orbiter. Hazards such as additional tile or Reinforced Carbon-Carbon (RCC) damage from a loose tool, safety tethers, crewmember or arm impact are introduced. Additionally, there are hazards to the crew which should be addressed. Crew hazards include laser injury, electrical shock, inability to return to the airlock for EMU failures or Orbiter rapid safing scenarios, as well as the potential inadvertent release of a crew member from the arm/boom. The aforementioned hazards are controlled in various ways. Generally, these controls are addressed operationally versus by design, as the majority of the interfaces are to the Orbiter and the Orbiter design did not originally account for tile repair. The Shuttle Remote Manipulator System (SRMS), for instance, was originally designed to deploy experiments, and therefore has insufficient design controls for retention of the Orbiter Boom Sensor System (OBSS). Although multiple methods to repair the Orbiter TPS exist, the majority of the hazards are applicable no matter which specific repair method is being performed. TPS Inspection performed via EVA also presents some of the same hazards. Therefore, the hazards common to all TPS inspection or repair methods will

  7. Dynamics, control and sensor issues pertinent to robotic hands for the EVA retriever system

    NASA Technical Reports Server (NTRS)

    Mclauchlan, Robert A.

    1987-01-01

    Basic dynamics, sensor, control, and related artificial intelligence issues pertinent to smart robotic hands for the Extra Vehicular Activity (EVA) Retriever system are summarized and discussed. These smart hands are to be used as end effectors on arms attached to manned maneuvering units (MMU). The Retriever robotic systems comprised of MMU, arm and smart hands, are being developed to aid crewmen in the performance of routine EVA tasks including tool and object retrieval. The ultimate goal is to enhance the effectiveness of EVA crewmen.

  8. EVA Human Health and Performance Benchmarking Study Overview and Development of a Microgravity Protocol

    NASA Technical Reports Server (NTRS)

    Norcross, Jason; Jarvis, Sarah; Bekdash, Omar; Cupples, Scott; Abercromby, Andrew

    2017-01-01

    The primary objective of this study is to develop a protocol to reliably characterize human health and performance metrics for individuals working inside various EVA suits under realistic spaceflight conditions. Expected results and methodologies developed during this study will provide the baseline benchmarking data and protocols with which future EVA suits and suit configurations (e.g., varied pressure, mass, center of gravity [CG]) and different test subject populations (e.g., deconditioned crewmembers) may be reliably assessed and compared. Results may also be used, in conjunction with subsequent testing, to inform fitness-for-duty standards, as well as design requirements and operations concepts for future EVA suits and other exploration systems.

  9. 21 CFR 177.1060 - n-Alkylglutarimide/acrylic copolymers.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false n-Alkylglutarimide/acrylic copolymers. 177.1060... Use Food Contact Surfaces § 177.1060 n-Alkylglutarimide/acrylic copolymers. n-Alkylglutarimide/acrylic...) Identity. For the purpose of this section, n-alkylglutarimide/acrylic copolymers are copolymers obtained...

  10. 21 CFR 175.210 - Acrylate ester copolymer coating.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Acrylate ester copolymer coating. 175.210 Section... Coatings § 175.210 Acrylate ester copolymer coating. Acrylate ester copolymer coating may safely be used as... prepared food, subject to the provisions of this section: (a) The acrylate ester copolymer is a...

  11. Synthesis of amphipathic block copolymers based on polyisobutylene and polyoxyethylene and their application in emulsion polymerization

    SciTech Connect

    Sar, B.

    1992-12-31

    Polymer colloids stabilized by polymeric surfactants are of great interest both commercially and academically. It has been found that these materials enhance latex stabilization in a number of applications. The polymeric surfactants are amphipathic block and graft copolymers containing both hydrophilic and hydrophobic moieties. The current study involved the synthesis of a series of amphipathic triblock copolymers, polyisobutylene-block-polyoxyethylene-block-polyisobutylene (PIB-b-POE-b-PIB), for use in the emulsion polymerization of styrene (STY), methyl methacrylate (MMA), and vinyl acetate (VAc). The stabilizing effectiveness of these triblock copolymers was studied as a function of their blocklength. When the molecular weight of the POE center block was changed from M{sub n} = 2,000 to 20,000 g/mole, stable lattices were obtained in emulsion polymerization with MMA, STY, and VAc as the monomers. In all cases, the polymerization rates remained constant, while the number of particles/volume decreased with increasing POE chain length. When the molecular weight of the PIB end blocks was changed from M{sub n} = 400 to 2,600 g/mole keeping the molecular weight of the POE center block constant at M{sub n} = 20,000 g/mole, the poly(methyl methacrylate) and poly(vinyl acetate) lattices exhibited similar behavior, i.e., the number of particles and particle sizes remained the same, but the rate of polymerization reached a maximum at 87 wt% POE content. In the case of poly(styrene) both the rate of polymerization and the number of particles remained constant. The emulsion polymerization of other monomers such as butadiene, acrylonitrile, methyl acrylate, ethyl acrylate, and butyl acrylate was carried out by using one triblock copolymer, i.e., PIB(400)-b-POE (8,000)-b-PIB-(400). Stable lattices were also formed in all cases.

  12. Rapid self-assembly of block copolymers to photonic crystals

    DOEpatents

    Xia, Yan; Sveinbjornsson, Benjamin R; Grubbs, Robert H; Weitekamp, Raymond; Miyake, Garret M; Atwater, Harry A; Piunova, Victoria; Daeffler, Christopher Scot; Hong, Sung Woo; Gu, Weiyin; Russell, Thomas P.

    2016-07-05

    The invention provides a class of copolymers having useful properties, including brush block copolymers, wedge-type block copolymers and hybrid wedge and polymer block copolymers. In an embodiment, for example, block copolymers of the invention incorporate chemically different blocks comprising polymer size chain groups and/or wedge groups that significantly inhibit chain entanglement, thereby enhancing molecular self-assembly processes for generating a range of supramolecular structures, such as periodic nanostructures and microstructures. The present invention also provides useful methods of making and using copolymers, including block copolymers.

  13. Microwave irradiation induced modifications on the interfaces in SAN/EVA/PVC and PVAc/BPA/PVP ternary polymer blends: Positron lifetime study

    NASA Astrophysics Data System (ADS)

    Dinesh, Meghala; Chikkakuntappa, Ranganathaiah

    2013-09-01

    Ternary polymer blends of poly(styrene-co-acrylonitrile)/poly(ethylene-co-vinylacetate)/poly(vinyl chloride) (SAN/EVA/PVC) and poly(vinyl acetate)/bisphenol A/polyvinylpyrrolidone (PVAc/BPA/PVP) with different compositions have been prepared by solvent casting method and characterized by positron lifetime spectroscopy and differential scanning calorimetry DSC. Phase modifications have been induced by irradiating the blends with microwave radiation. These changes have been monitored by measuring the free-volume content in the blends. The results clearly show improved interactions between the constituent polymers of the blends upon microwave irradiation. However, the free-volume data and DSC measurements are found to be inadequate to reveal the changes at the interfaces and the interfaces determine the final properties of the blend. For this we have used hydrodynamic interaction (αij) approach developed by us to measure strength of hydrodynamic interaction at the interfaces. These results show that microwave irradiation stabilizes the interfaces if the blend contains strong polar groups. SAN/EVA/PVC blend shows an increased effective hydrodynamic interaction from -3.18 to -4.85 at composition 50/35/15 upon microwave irradiation and PVAc/BPA/PVP blend shows an increased effective hydrodynamic interaction from -3.81 to -7.57 at composition 20/50/30 after irradiation.

  14. Effect of TiO2-Crystal Forms on the Photo-Degradation of EVA/PLA Blend Under Accelerated Weather Testing

    NASA Astrophysics Data System (ADS)

    Van Cong, Do; Trang, Nguyen Thi Thu; Giang, Nguyen Vu; Lam, Tran Dai; Hoang, Thai

    2016-05-01

    Photo-degradation of poly (ethylene-co-vinyl acetate) (EVA)/poly (lactic acid) (PLA) blend and EVA/PLA/TiO2 nanocomposites was carried out under accelerated weather testing conditions by alternating cycles of ultraviolet (UV) light and moisture at controlled and elevated temperatures. The characters, properties, and morphology of these materials before and after accelerated weather testing were determined by Fourier transform infrared spectroscopy, colour changes, viscosity, tensile test, thermogravimetric analysis, and field emission scanning electron microscopy. The increases in the content of oxygen-containing groups, colour changes; the decreases in viscosity, tensile properties, and thermal stability of these materials after accelerated weather testing are the evidence for the photo-degradation of the blend and nanocomposites. After accelerated weather testing, the appearance of many micro-holes and micro-pores on the surface of the collected samples was observed. The photo-degradation degree of the nanocomposites depended on the TiO2-crystal form. Rutile TiO2 do not enhance the degradation, but anatase and mixed crystals TiO2 nanoparticles promoted the degradation of the nanocomposites. Particularly, the mixed crystals TiO2 nanoparticles showed the highest photo-catalytic activity of the nanocomposites.

  15. Thermal stability of poly(ethylene-co-vinyl acetate) based materials

    SciTech Connect

    Patel, Mogon; Pitts, Simon; Beavis, Peter; Robinson, Mathew; Morrell, Paul; Khan, Niaz; Khan, Imran; Pockett, Nicola; Letant, Sonia; Von White, Gregory; Labouriau, Andrea

    2013-03-26

    The thermal stability properties of poly (ethylene-co-vinyl acetate) composites have been studied in support of our core programmes in materials qualification and life assessment. The material is used as a binder phase for boron particles in highly filled (70 wt %) composites. Our studies show that the uncured resin readily accumulates acetic acid through hydrolysis of the pendent acetate groups which alters the acidity (pH) of the material. Thermal desorption studies in combination with gas-chromatography-mass spectrometry show that the resin readily evolves acetic acid when thermally aged to temperatures up to 75°C. Gel Permeation Chromatography (GPC) suggests that thermal ageing induces a gradual reduction in resin molecular weight and confirms the susceptibility of the material to chain scission. Heating at elevated temperatures in excess of 300oC is required to induce significant changes in the carbon skeleton through deacetylation and dehydration processes and the production of unsaturated main chain double bonds. Overall, the mechanical response of these filled composites are found to be relatively complex with the extent of polymer-filler interactions possibly playing an important role in determining key engineering properties. Mechanical property studies confirm a small but significant decrease in modulus presumably linked to thermally induced chain scission of the EVA binder.

  16. Thermal stability of poly(ethylene-co-vinyl acetate) based materials

    DOE PAGES

    Patel, Mogon; Pitts, Simon; Beavis, Peter; ...

    2013-03-26

    The thermal stability properties of poly (ethylene-co-vinyl acetate) composites have been studied in support of our core programmes in materials qualification and life assessment. The material is used as a binder phase for boron particles in highly filled (70 wt %) composites. Our studies show that the uncured resin readily accumulates acetic acid through hydrolysis of the pendent acetate groups which alters the acidity (pH) of the material. Thermal desorption studies in combination with gas-chromatography-mass spectrometry show that the resin readily evolves acetic acid when thermally aged to temperatures up to 75°C. Gel Permeation Chromatography (GPC) suggests that thermal ageingmore » induces a gradual reduction in resin molecular weight and confirms the susceptibility of the material to chain scission. Heating at elevated temperatures in excess of 300oC is required to induce significant changes in the carbon skeleton through deacetylation and dehydration processes and the production of unsaturated main chain double bonds. Overall, the mechanical response of these filled composites are found to be relatively complex with the extent of polymer-filler interactions possibly playing an important role in determining key engineering properties. Mechanical property studies confirm a small but significant decrease in modulus presumably linked to thermally induced chain scission of the EVA binder.« less

  17. Efficacy of Wrist/Palm Warming as an EVA Countermeasure to Maintain Finger Comfort in Cold Conditions During EVA

    NASA Technical Reports Server (NTRS)

    Koscheyev, Victor S.; Leon, Gloria R.; Trevino, Robert C.

    2000-01-01

    This study explored the effectiveness of local wrist/palm warming as a potential countermeasure for providing finger comfort during extended duration EVA. Methods: Six subjects (5 males and 1 female) were evaluated in a sagitally divided liquid cooling/warming garment (LCWG) with modified liquid cooling/warming (LCW) gloves in three different experimental conditions. Condition 1: Stage 1- no LCWG; chamber adaptation with LCW glove inlet water temperature 33 C; Stage 2-LCW glove inlet water temperature cooled to 8 C; Stage 3-LCW glove inlet water temperature warmed to 45 C; Condition 2: Stage1-LCWG and LCW glove inlet water temperature 33 C; Stage 2-LCWG inlet temperature cooled to 31 C, LCW gloves, 8 C; Stage 3-LCWG inlet water temperature remains at 31 C, LCW glove inlet water temperature warmed to 45 C; Condition 3: Stage l -LCWG and LCW gloves 33 C; Stage 2-LCWG inlet water temperature cooled to 28 C, LCW gloves, 8 C; Stage 3-LCWG remains at 28 C, LCW glove water temperature warmed to 45 C. Results: Wrist/palm area warming significantly increased finger temperature (Tfing) and blood perfusion in Stage 3 compared to Stage 2. The LCW gloves were most effective in increasing Stage 3 Tfing in Condition 1; and in increasing blood perfusion in Conditions 1 and 2 compared to Condition 3. Ratings of subjective perception of heat in the hand and overall body heat were higher at Stage 3 than Stage 2, with no significant differences across Conditions. Conclusions: Local wrist/palm warming was effective in increasing blood circulation to the distal extremities, suggesting the potential usefulness of this technique for increasing astronaut thermal comfort during EVA while decreasing power requirements. The LCW gloves were effective in heating the highly cooled fingers when the overall body was in a mild heat deficit.

  18. Microphase separation in random multiblock copolymers

    NASA Astrophysics Data System (ADS)

    Govorun, E. N.; Chertovich, A. V.

    2017-01-01

    Microphase separation in random multiblock copolymers is studied with the mean-field theory assuming that long blocks of a copolymer are strongly segregated, whereas short blocks are able to penetrate into "alien" domains and exchange between the domains and interfacial layer. A bidisperse copolymer with blocks of only two sizes (long and short) is considered as a model of multiblock copolymers with high polydispersity in the block size. Short blocks of the copolymer play an important role in the microphase separation. First, their penetration into the "alien" domains leads to the formation of joint long blocks in their own domains. Second, short blocks localized at the interface considerably change the interfacial tension. The possibility of penetration of short blocks into the "alien" domains is controlled by the product χ Nsh (χ is the Flory-Huggins interaction parameter and Nsh is the short block length). At not very large χ Nsh , the domain size is larger than that for a regular copolymer consisting of the same long blocks as in the considered random copolymer. At a fixed mean block size, the domain size grows with an increase in the block size dispersity, the rate of the growth being dependent of the more detailed parameters of the block size distribution.

  19. Automatic antenna switching design for Extra Vehicular Activity (EVA) communication system

    NASA Technical Reports Server (NTRS)

    Randhawa, Manjit S.

    1987-01-01

    An Extra Vehicular Activity (EVA) crewmember had two-way communications with the space station in the Ku-band frequency (12 to 18 GHz). The maximum range of the EVA communications link with the space station is approximately one kilometer for nominal values for transmitter power, antenna gains, and receiver noise figure. The EVA Communications System, that will continue to function regardless of the astronaut's position and orientation, requires an antenna system that has full spherical coverage. Three or more antennas that can be flush mounted on the astronaut's space suit (EMU) and/or his propulsive backpack (MMU), will be needed to provide the desired coverage. As the astronaut moves in the space station, the signal received by a given EVA antenna changes. An automatic antenna switching system is needed that will switch the communication system to the antenna with the largest signal strength. A design for automatic antenna switching is presented and discussed.

  20. EASE (Experimental Assembly of Structures in EVA) overview of selected results

    NASA Technical Reports Server (NTRS)

    Akin, David L.

    1987-01-01

    Experimental Assembly of Structures in EVA (EASE) objectives, experimental protocol, neutral buoyancy simulation, task time distribution, assembly task performance, metabolic rate/biomedical readouts are summarized. This presentation is shown in charts, figures, and graphs.

  1. The First Results of the Russian EVA Space Suits Operation in the International Space Station

    NASA Astrophysics Data System (ADS)

    Abramov, I. P.; Albats, E. A.; Glazov, G. M.

    The year of 2001 saw the first EVAs of the International Space Station (ISS) crews using the Russian "Orlan-M" space suits. This marked the beginning of a new stage of activities on putting into operation of the next ISS modules. The paper reviews the results of the Russian space suits' operation in the course of extravehicular activity (EVA) by the crews of the first ISS expeditions. The paper also reviews differences in operation of the "Orlan-M" in the ISS and "Mir" orbiting station resulting from space suit (SS) systems design, peculiarities of the station airlocks and EVA performance methods. The paper presents data on EVA results and comments on space suit systems' operation. The paper gives diagrams for main parameters of the space suits' life support systems (LSS) and comments about them. In conclusion the paper reviews the "Orlan-M" improvements being performed and prospects of "Orlan-M" usage in the ISS.

  2. A synopsis of the EVA training conducted on EASE/ACCESS for STS-61-B

    NASA Technical Reports Server (NTRS)

    Havens, Kathryn A.

    1987-01-01

    Experimental Assembly of Structure in EVA (EASE)/Assembly Concept for Construction of Erectable Space Structures (ACCESS) training problems; photography/television coverage; training schedules; flight data file (FDF), and flight rules production are summarized.

  3. The Potential of Wearable Sensor Technology for EVA Glove Ergonomic Evaluation

    NASA Technical Reports Server (NTRS)

    Reid, Christopher R.; McFarland, Shane M.; Norcross, Jason R.; Rajulu, Sudhakar

    2014-01-01

    Injuries to the hands are common among astronauts who train for extravehicular activity (EVA). Many of these injuries refer to the gloves worn during EVA as the root cause. While pressurized, the bladder and outer material of these gloves restrict movement and create pressure points while performing tasks, sometimes resulting in pain, muscle fatigue, abrasions, and occasionally a more severe injury, onycholysis (fingernail delamination). The most common injury causes are glove contact (pressure point/rubbing), ill-fitting gloves, and/or performing EVA tasks in pressurized gloves. A brief review of the Lifetime Surveillance of Astronaut Health's injury database reveals over 57% of the total injuries to the upper extremities during EVA training occurred either to the metacarpophalangeal (MCP) joint, fingernail, or the fingertip. Twenty-five of these injuries resulted in a diagnosis of onycholysis.

  4. The Potential of Wearable Sensor Technology for EVA Glove Ergonomic Evaluation

    NASA Technical Reports Server (NTRS)

    Reid, Christopher R.; McFarland, Shane; Norcross, Jason R.; Rajulu, Sudhakar

    2014-01-01

    Injuries to the hands are common among astronauts who train for extravehicular activity (EVA). Many of these injuries refer to the gloves worn during EVA as the root cause. While pressurized, the bladder and outer material of these gloves restrict movement and create pressure points while performing tasks, sometimes resulting in pain, muscle fatigue, abrasions, and occasionally a more severe injury, onycholysis (fingernail delamination). The most common injury causes are glove contact (pressure point/rubbing), ill-fitting gloves, and/or performing EVA tasks in pressurized gloves. A brief review of the Lifetime Surveillance of Astronaut Health's injury database reveals over 57% of the total injuries to the upper extremities during EVA training occurred either to the metacarpophalangeal (MCP) joint, fingernail, or the fingertip. Twenty-five of these injuries resulted in a diagnosis of onycholysis

  5. The micro conical system: Lessons learned from a successful EVA/robot-compatible mechanism

    NASA Technical Reports Server (NTRS)

    Gittleman, Mark; Johnston, Alistair

    1996-01-01

    The Micro Conical System (MCS) is a three-part, multi-purpose mechanical interface system used for acquiring and manipulating masses on-orbit by either extravehicular activity (EVA) or telerobotic means. The three components of the system are the micro conical fitting (MCF), the EVA micro tool (EMCT), and the Robot Micro Conical Tool (RMCT). The MCS was developed and refined over a four-year period. This period culminated with the delivery of 358 Class 1 and Class 2 micro conical fittings for the International Space Station and with its first use in space to handle a 1272 kg (2800 lbm) Spartan satellite (11000 times greater than the MCF mass) during an EVA aboard STS-63 in February, 1995. The micro conical system is the first successful EVA/robot-compatible mechanism to be demonstrated in the external environment aboard the U.S. Space Shuttle.

  6. FY13 High Performance EVA Glove (HPEG) Collaboration: Glove Injury Data Mining Effort - Training Data Overview

    NASA Technical Reports Server (NTRS)

    Reid, Christopher; Benson, Elizabeth; England, Scott; Charvat, Jacqueline; Norcross, Jason; McFarland, Shane; Rajulu, Sudhakar

    2014-01-01

    From the time hand-intensive tasks were first created for EVAs, discomforts and injuries have been noted.. There have been numerous versions of EVA gloves for US crew over the past 50 years, yet pain and injuries persist. The investigation team was tasked with assisting in a glove injury assessment for the High Performance EVA Glove (HPEG) project.center dot To aid in this assessment, the team was asked to complete the following objectives: - First, to develop the best current understanding of what glove-related injuries have occurred to date, and when possible, identify the specific mechanisms that caused those injuries - Second, to create a standardized method for comparison of glove injury potential from one glove to another. center dot The overall goal of the gloved hand injury assessment is to utilize ergonomics in understanding how these glove injuries are occurring, and to propose mitigations to current designs or design changes in the next generation of EVA gloves.

  7. Block Copolymer Membranes for Biofuel Purification

    NASA Astrophysics Data System (ADS)

    Evren Ozcam, Ali; Balsara, Nitash

    2012-02-01

    Purification of biofuels such as ethanol is a matter of considerable concern as they are produced in complex multicomponent fermentation broths. Our objective is to design pervaporation membranes for concentrating ethanol from dilute aqueous mixtures. Polystyrene-b-polydimethylsiloxane-b-polystyrene block copolymers were synthesized by anionic polymerization. The polydimethylsiloxane domains provide ethanol-transporting pathways, while the polystyrene domains provide structural integrity for the membrane. The morphology of the membranes is governed by the composition of the block copolymer while the size of the domains is governed by the molecular weight of the block copolymer. Pervaporation data as a function of these two parameters will be presented.

  8. Injectible bodily prosthetics employing methacrylic copolymer gels

    DOEpatents

    Mallapragada, Surya K.; Anderson, Brian C.

    2007-02-27

    The present invention provides novel block copolymers as structural supplements for injectible bodily prosthetics employed in medical or cosmetic procedures. The invention also includes the use of such block copolymers as nucleus pulposus replacement materials for the treatment of degenerative disc disorders and spinal injuries. The copolymers are constructed by polymerization of a tertiary amine methacrylate with either a (poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) polymer, such as the commercially available Pluronic.RTM. polymers, or a poly(ethylene glycol) methyl ether polymer.

  9. Utilization of ISS to Develop and Test Operational Concepts and Hardware for Low-Gravity Terrestrial EVA

    NASA Technical Reports Server (NTRS)

    Gast, Matthew A.

    2010-01-01

    NASA has considerable experience in two areas of Extravehicular Activities (EVA). The first can be defined as microgravity, orbital EVAs. This consists of everything done in low Earth orbit (LEO), from the early, proof of concept EVAs conducted during the Gemini program of the 1960s, to the complex International Space Station (ISS) assembly tasks of the first decade of the 21st century. The second area of expertise is comprised of those EVAs conducted on the lunar surface, under a gravitational force one-sixth that of Earth. This EVA expertise encapsulates two extremes - microgravity and Earthlike gravitation - but is insufficient as humans expand their exploration purview, most notably with respect to spacewalks conducted on very low-gravity bodies, such as near- Earth objects (NEO) and the moons of Mars. The operational and technical challenges of this category of EVA have yet to be significantly examined, and as such, only a small number of operational concepts have been proposed thus far. To ensure mission success, however, EVA techniques must be developed and vetted to allow the selection of operational concepts that can be utilized across an assortment of destinations whose physical characteristics vary. This paper examines the utilization of ISS-based EVAs to test operational concepts and hardware in preparation for a low-gravity terrestrial EVA. While the ISS cannot mimic some of the fundamental challenges of a low-gravity terrestrial EVA - such as rotation rate and surface composition - it may be the most effective test bed available.

  10. Overview of EVA PRA for TPS Repair for Hubble Space Telescope Servicing Mission

    NASA Technical Reports Server (NTRS)

    Bigler, Mark; Duncan, Gary; Roeschel, Eduardo; Canga, Michael

    2010-01-01

    Following the Columbia accident in 2003, NASA developed techniques to repair the Thermal Protection System (TPS) in the event of damage to the TPS as one of several actions to reduce the risk to future flights from ascent debris, micro-meteoroid and/or orbital debris (MMOD). Other actions to help reduce the risk include improved inspection techniques, reduced shedding of debris from the External Tank and ability to rescue the crew with a launch on need vehicle. For the Hubble Space Telescope (HST) Servicing Mission the crew rescue capability was limited by the inability to safe haven on the International Space Station (ISS), resulting in a greater reliance on the repair capability. Therefore it was desirable to have an idea of the risk associated with conducting a repair, where the repair would have to be conducted using an Extra-Vehicular Activity (EVA). Previously, focused analyses had been conducted to quantify the risk associated with certain aspects of an EVA, for example the EVA Mobility Unit (EMU) or Space Suit; however, the analyses were somewhat limited in scope. A complete integrated model of an EVA which could quantify the risk associated with all of the major components of an EVA had never been done before. It was desired to have a complete integrated model to be able to assess the risks associated with an EVA to support the Space Shuttle Program (SSP) in making risk informed decisions. In the case of the HST Servicing Mission, this model was developed to assess specifically the risks associated with performing a TPS repair EVA. This paper provides an overview of the model that was developed to support the HST mission in the event of TPS damage. The HST Servicing Mission was successfully completed on May 24th 2009 with no critical TPS damage; therefore the model was not required for real-time mission support. However, it laid the foundation upon which future EVA quantitative risk assessments could be based.

  11. Approaches to decompression safety support of EVA for orbital and interplanetary missions

    NASA Astrophysics Data System (ADS)

    Katuntsev, Vladimir P.

    2010-01-01

    The paper is devoted to the analysis of possible methods for decompression safety support of extravehicular activity (EVA) in order to ground the perspective approaches for solution of decompression sickness (DCS) problem in space missions of the near and distant future. Current DCS risk mitigation strategies reduce operational efficiency: preoxygenation extends the time required on preparation to EVA. The crewmembers often experience general and hand fatigue during long EVA due to the lack of flexibility of space suits enclosure operated at 30-40 kPa. To create the safe and comfortable working conditions for EVA crewmembers on the Lunar and Martian surfaces the main biomedical requirements to a planetary space suit have to include low mass of EVA system, high mobility and flexibility of space suit enclosure and reliable protection against DCS with a short or zero preoxygenation period. Reviewed here are the possibilities for the use of preoxygenation, hypobaric gas atmosphere in space cabin and/or planetary habitat, idea of substitution of nitrogen in normobaric gas atmosphere to another inert gas (helium and neon) as countermeasures against DCS in EVA crewmembers. Physiological aspects of the conception for space suit with high operating pressure are considered.

  12. EVA1A/TMEM166 Regulates Embryonic Neurogenesis by Autophagy

    PubMed Central

    Li, Mengtao; Lu, Guang; Hu, Jia; Shen, Xue; Ju, Jiabao; Gao, Yuanxu; Qu, Liujing; Xia, Yan; Chen, Yingyu; Bai, Yun

    2016-01-01

    Summary Self-renewal and differentiation of neural stem cells is essential for embryonic neurogenesis, which is associated with cell autophagy. However, the mechanism by which autophagy regulates neurogenesis remains undefined. Here, we show that Eva1a/Tmem166, an autophagy-related gene, regulates neural stem cell self-renewal and differentiation. Eva1a depletion impaired the generation of newborn neurons, both in vivo and in vitro. Conversely, overexpression of EVA1A enhanced newborn neuron generation and maturation. Moreover, Eva1a depletion activated the PIK3CA-AKT axis, leading to the activation of the mammalian target of rapamycin and the subsequent inhibition of autophagy. Furthermore, addition of methylpyruvate to the culture during neural stem cell differentiation rescued the defective embryonic neurogenesis induced by Eva1a depletion, suggesting that energy availability is a significant factor in embryonic neurogenesis. Collectively, these data demonstrated that EVA1A regulates embryonic neurogenesis by modulating autophagy. Our results have potential implications for understanding the pathogenesis of neurodevelopmental disorders caused by autophagy dysregulation. PMID:26905199

  13. EVA1A/TMEM166 Regulates Embryonic Neurogenesis by Autophagy.

    PubMed

    Li, Mengtao; Lu, Guang; Hu, Jia; Shen, Xue; Ju, Jiabao; Gao, Yuanxu; Qu, Liujing; Xia, Yan; Chen, Yingyu; Bai, Yun

    2016-03-08

    Self-renewal and differentiation of neural stem cells is essential for embryonic neurogenesis, which is associated with cell autophagy. However, the mechanism by which autophagy regulates neurogenesis remains undefined. Here, we show that Eva1a/Tmem166, an autophagy-related gene, regulates neural stem cell self-renewal and differentiation. Eva1a depletion impaired the generation of newborn neurons, both in vivo and in vitro. Conversely, overexpression of EVA1A enhanced newborn neuron generation and maturation. Moreover, Eva1a depletion activated the PIK3CA-AKT axis, leading to the activation of the mammalian target of rapamycin and the subsequent inhibition of autophagy. Furthermore, addition of methylpyruvate to the culture during neural stem cell differentiation rescued the defective embryonic neurogenesis induced by Eva1a depletion, suggesting that energy availability is a significant factor in embryonic neurogenesis. Collectively, these data demonstrated that EVA1A regulates embryonic neurogenesis by modulating autophagy. Our results have potential implications for understanding the pathogenesis of neurodevelopmental disorders caused by autophagy dysregulation.

  14. Curable polyphosphazene copolymers and terpolymers

    NASA Technical Reports Server (NTRS)

    Reynard, Kennard A. (Inventor); Rose, Selwyn H. (Inventor)

    1976-01-01

    Copolymers and terpolymers comprising randomly repeating units represented by the general formulae ##EQU1## wherein the R' radicals contain OH functionality and R being at least one member of the group of monovalent radicals selected from alkyl, substituted alkyl, aryl, substituted aryl and arylalkyl, and R' is represented by ##EQU2## wherein Q represents either --(CH.sub.2).sub. n or --C.sub.6 H.sub.4 X(CH.sub.2).sub. m, the --X(CH.sub.2).sub. m group being either meta or para and n is an integer from 1 to 6, m is an integer from 1 to 3, X is O or CH.sub.2, and R is H or a lower alkyl radical with up to four carbon atoms (methyl, ethyl, etc.). The ratio of R to R' is between 99.5 to 0.5 and 65 to 35.

  15. Organosilane Polymers. III. Block Copolymers.

    DTIC Science & Technology

    1980-04-01

    5446 (1969) 9) R. West, J. Polym. Sci., C, 29, 65 (1970) 10) V.F. Traven and R. West, J. Am. Chem. Soc., 95, 6824 (1973) 11) W.G. Boberski and-A.L...COMPOSITION Alkyl H/Aryl H (2 ) Copolymer Method,1 , Calculated Found 111-3 A 0.72 0.73 B 0.72 0.73 111-5 A 0.80 0.85 B 0.80 0.80 111-8 A 1.0 1.4 B 1.0...1.1 (1) A: Chloro-oligomer added to lithio-oligomer. B : Lithio-oligomer added to chloro-oligomer. (2) By HI-NMR TABLE 2 INFRA-RED ABSORPTIONS

  16. Electrostatic control of block copolymer morphology

    NASA Astrophysics Data System (ADS)

    Sing, Charles E.; Zwanikken, Jos W.; Olvera de La Cruz, Monica

    2014-07-01

    Energy storage is at present one of the foremost issues society faces. However, material challenges now serve as bottlenecks in technological progress. Lithium-ion batteries are the current gold standard to meet energy storage needs; however, they are limited owing to the inherent instability of liquid electrolytes. Block copolymers can self-assemble into nanostructures that simultaneously facilitate ion transport and provide mechanical stability. The ions themselves have a profound, yet previously unpredictable, effect on how these nanostructures assemble and thus the efficiency of ion transport. Here we demonstrate that varying the charge of a block copolymer is a powerful mechanism to predictably tune nanostructures. In particular, we demonstrate that highly asymmetric charge cohesion effects can induce the formation of nanostructures that are inaccessible to conventional uncharged block copolymers, including percolated phases desired for ion transport. This vastly expands the design space for block copolymer materials and is informative for the versatile design of battery electrolyte materials.

  17. Block copolymer structures in nano-pores

    NASA Astrophysics Data System (ADS)

    Pinna, Marco; Guo, Xiaohu; Zvelindovsky, Andrei

    2010-03-01

    We present results of coarse-grained computer modelling of block copolymer systems in cylindrical and spherical nanopores on Cell Dynamics Simulation. We study both cylindrical and spherical pores and systematically investigate structures formed by lamellar, cylinders and spherical block copolymer systems for various pore radii and affinity of block copolymer blocks to the pore walls. The obtained structures include: standing lamellae and cylinders, ``onions,'' cylinder ``knitting balls,'' ``golf-ball,'' layered spherical, ``virus''-like and mixed morphologies with T-junctions and U-type defects [1]. Kinetics of the structure formation and the differences with planar films are discussed. Our simulations suggest that novel porous nano-containers can be formed by confining block copolymers in pores of different geometries [1,2]. [4pt] [1] M. Pinna, X. Guo, A.V. Zvelindovsky, Polymer 49, 2797 (2008).[0pt] [2] M. Pinna, X. Guo, A.V. Zvelindovsky, J. Chem. Phys. 131, 214902 (2009).

  18. Arbitrary lattice symmetries via block copolymer nanomeshes

    PubMed Central

    Majewski, Pawel W.; Rahman, Atikur; Black, Charles T.; Yager, Kevin G.

    2015-01-01

    Self-assembly of block copolymers is a powerful motif for spontaneously forming well-defined nanostructures over macroscopic areas. Yet, the inherent energy minimization criteria of self-assembly give rise to a limited library of structures; diblock copolymers naturally form spheres on a cubic lattice, hexagonally packed cylinders and alternating lamellae. Here, we demonstrate multicomponent nanomeshes with any desired lattice symmetry. We exploit photothermal annealing to rapidly order and align block copolymer phases over macroscopic areas, combined with conversion of the self-assembled organic phase into inorganic replicas. Repeated photothermal processing independently aligns successive layers, providing full control of the size, symmetry and composition of the nanoscale unit cell. We construct a variety of symmetries, most of which are not natively formed by block copolymers, including squares, rhombuses, rectangles and triangles. In fact, we demonstrate all possible two-dimensional Bravais lattices. Finally, we elucidate the influence of nanostructure on the electrical and optical properties of nanomeshes. PMID:26100566

  19. Salt Complexation in Block Copolymer Thin Films

    SciTech Connect

    Kim,S.; Misner, M.; Yang, L.; Gang, O.; Ocko, B.; Russell, T.

    2006-01-01

    Ion complexation within cylinder-forming block copolymer thin films was found to affect the ordering process of the copolymer films during solvent annealing, significantly enhancing the long-range positional order. Small amounts of alkali halide or metal salts were added to PS-b-PEO, on the order of a few ions per chain, where the salt complexed with the PEO block. The orientation of the cylindrical microdomains strongly depended on the salt concentration and the ability of the ions to complex with PEO. The process shows large flexibility in the choice of salt used, including gold or cobalt salts, whereby well-organized patterns of nanoparticles can be generated inside the copolymer microdomains. By further increasing the amount of added salts, the copolymer remained highly ordered at large degrees of swelling and demonstrated long-range positional correlations of the microdomains in the swollen state, which holds promise as a route to addressable media.

  20. Reactivity ratios for organotin copolymer systems.

    PubMed

    El-Newehy, Mohamed H; Al-Deyab, Salem S; Al-Hazmi, Ali Mohsen Ali

    2010-04-15

    Di(tri-n-butyltin) itaconate (DTBTI) and monoethyl tributyltin fumarate (METBTF) were synthesized as organotin monomers. The organotin monomers were copolymerized with styrene (ST) and methyl methacrylate (MMA) via a free radical polymerization technique. The overall conversion was kept low (copolymer composition was determined from tin analysis. The synthesized monomers and copolymers were characterized by elemental analysis, 1H- and 13C-NMR, and FTIR spectroscopy.

  1. Method for making block siloxane copolymers

    DOEpatents

    Butler, N.L.; Jessop, E.S.; Kolb, J.R.

    1981-02-25

    A method for synthesizing block polysiloxane copolymers is disclosed. Diorganoscyclosiloxanes and an end-blocking compound are interacted in the presence of a ring opening polymerization catalyst, producing a blocked prepolymer. The prepolymer is then interacted with a silanediol, resulting in condensation polymerization of the prepolymers. A second end-blocking compound is subsequently introduced to end-cap the polymers and copolymers formed from the condensation polymerization.

  2. Responsive Copolymers for Enhanced Petroleum Recovery

    SciTech Connect

    McCormick, C.; Hester, R.

    2001-02-27

    The objectives of this work was to: synthesize responsive copolymer systems; characterize molecular structure and solution behavior; measure rheological properties of aqueous fluids in fixed geometry flow profiles; and to tailor final polymer compositions for in situ rheology control under simulated conditions. This report focuses on the synthesis and characterization of novel stimuli responsive copolymers, the investigation of dilute polymer solutions in extensional flow and the design of a rheometer capable of measuring very dilute aqueous polymer solutions at low torque.

  3. Method for making block siloxane copolymers

    DOEpatents

    Butler, Nora; Jessop, Edward S.; Kolb, John R.

    1982-01-01

    A method for synthesizing block polysiloxane copolymers. Diorganoscyclosiloxanes and an end-blocking compound are interacted in the presence of a ring opening polymerization catalyst, producing a blocked prepolymer. The prepolymer is then interacted with a silanediol, resulting in condensation polymerization of the prepolymers. A second end-blocking compound is subsequently introduced to end-cap the polymers and copolymers formed from the condensation polymerization.

  4. Heat shrinkability of electron-beam-modified thermoplastic elastomeric films from blends of ethylene-vinylacetate copolymer and polyethylene

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, S.; Chaki, T. K.; Bhowmick, Anil K.

    2000-11-01

    The heat shrinkability of electron-beam-irradiated thermoplastic elastomeric films from blends of ethylene-vinylacetate copolymer (EVA) and low-density polyethylene (LDPE) has been investigated in this paper. The effects of temperature, time and extent of stretching and shrinkage temperature and time have been reported. Based on the above data, the optimized conditions in terms of high heat shrinkage and low amnesia rating have been evaluated. Influence of radiation doses (0-500 kGy), multifunctional sensitizer levels (ditrimethylol propane tetraacrylate, DTMPTA), and blend proportions on heat shrinkability has been explained with the help of gel fraction and X-ray data. With the increase in radiation dose, gel fraction increases, which in turn gives rise to low values of heat shrinkage and amnesia rating. At a constant radiation dose and blend ratio, percent heat shrinkage is found to decrease with increase in DTMPTA level. Gel content increases with the increase in EVA content of the blend at a constant radiation dose and monomer level, giving rise to decrease in heat shrinkability. Heat shrinkage increases with the increase in percent crystallinity, although the amnesia rating follows the reverse trend.

  5. STS-111 Astronaut Perrin Performs Extra Vehicular Activity (EVA)

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The STS-111 mission, the 14th Shuttle mission to visit the International Space Station (ISS), was launched on June 5, 2002 aboard the Space Shuttle Orbiter Endeavour. On board were the STS-111 and Expedition Five crew members. Astronauts Kerneth D. Cockrell, commander; Paul S. Lockhart, pilot; and mission specialists Franklin R. Chang-Diaz and Philippe Perrin were the STS-111 crew members. Expedition Five crew members included Cosmonaut Valeri G. Korzun, commander; Astronaut Peggy A. Whitson and Cosmonaut Sergei Y. Treschev, flight engineers. Three space walks enabled the STS-111 crew to accomplish the delivery and installation of the Mobile Remote Servicer Base System (MBS), an important part of the Station's Mobile Servicing System that allows the robotic arm to travel the length of the Station, which is necessary for future construction tasks. In this photograph, Astronaut Philippe Perrin, representing CNES, the French Space Agency, participates in the second scheduled EVA. During the space walk, Perrin and Chang-Diaz attached power, data, and video cables from the ISS to the MBS, and used a power wrench to complete the attachment of the MBS onto the Mobile Transporter (MT).

  6. Further analysis of EVA self-rescue data

    NASA Astrophysics Data System (ADS)

    Brody, Adam R.

    A means for rescuing a stranded extravehicular activity (EVA) astronaut is necessary to ensure safe space station operations. One promising device is a hand-held thruster similar to the Hand-Held Maneuvering Unit (HHMU) from the Gemini and Skylab programs. A study was performed in the Virtual Interactive Environment Workstation (VIEW) at NASA Ames Research Center. Three Initial (Separation) Velocities (0.5, 1.0, and 1.5 m/s) were crossed with five Initial spin velocities (0, +/- 0.1, +/- 0.3) to yield 15 different trials. An Attitude Hold system was also modeled, which, when combined with the 15 combinations of separation and spin velocity, provided 30 distinct trails. Recent examinations of the data reveal that Initial (Separation) Velocity and Initial Spin Velocity each produced main effects and combined to produce an interaction effect on Solution Time. Solution Time increased with Initial Velocity and absolute Initial Spin Velocity. Final Roll Angle also increased Initial Spin Velocity. Attitude Hole Fuel increased with absolute Initial Spin Velocity. Interaction effects revealed that main effects were less pronounced at the lowest Initial Velocity level.

  7. STS-61B Astronaut Spring During EASE Extravehicular Activity (EVA)

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The crew assigned to the STS-61B mission included Bryan D. O'Conner, pilot; Brewster H. Shaw, commander; Charles D. Walker, payload specialist; mission specialists Jerry L. Ross, Mary L. Cleave, and Sherwood C. Spring; and Rodolpho Neri Vela, payload specialist. Launched aboard the Space Shuttle Atlantis November 28, 1985 at 7:29:00 pm (EST), the STS-61B mission's primary payload included three communications satellites: MORELOS-B (Mexico); AUSSAT-2 (Australia); and SATCOM KU-2 (RCA Americom). Two experiments were conducted to test assembling erectable structures in space: EASE (Experimental Assembly of Structures in Extravehicular Activity), and ACCESS (Assembly Concept for Construction of Erectable Space Structure). In a joint venture between NASA/Langley Research Center in Hampton, Virginia, and the Marshall Space Flight Center (MSFC), the EASE and ACCESS were developed and demonstrated at MSFC's Neutral Buoyancy Simulator (NBS). In this STS-61B onboard photo, astronaut Spring was working on the EASE during an Extravehicular Activity (EVA). The primary objective of this experiment was to test the structural assembly concepts for suitability as the framework for larger space structures and to identify ways to improve the productivity of space construction.

  8. EVA Suit R and D for Performance Optimization

    NASA Technical Reports Server (NTRS)

    Cowley, Matthew S.; Harvill, Lauren; Benson, Elizabeth; Rajulu, Sudhakar

    2014-01-01

    Designing a planetary suit is very complex and often requires difficult trade-offs between performance, cost, mass, and system complexity. To verify that new suit designs meet requirements, full prototypes must be built and tested with human subjects. However, numerous design iterations will occur before the hardware meets those requirements. Traditional draw-prototype-test paradigms for R&D are prohibitively expensive with today's shrinking Government budgets. Personnel at NASA are developing modern simulation techniques which focus on human-centric designs by creating virtual prototype simulations and fully adjustable physical prototypes of suit hardware. During the R&D design phase, these easily modifiable representations of an EVA suit's hard components will allow designers to think creatively and exhaust design possibilities before they build and test working prototypes with human subjects. It allows scientists to comprehensively benchmark current suit capabilities and limitations for existing suit sizes and sizes that do not exist. This is extremely advantageous and enables comprehensive design down-selections to be made early in the design process, enables the use of human performance as design criteria, and enables designs to target specific populations

  9. Reconfiguration of EVA Modular Truss Assemblies using an Anthropomorphic Robot

    NASA Astrophysics Data System (ADS)

    Diftler, Myron A.; Doggett, William R.; Mehling, Joshua S.; King, Bruce D.

    2006-01-01

    NASA relies heavily on astronauts to perform Extra-Vehicular Activities (EVA) as part of space construction and maintenance operations. Astronauts provide an unmatched capability and flexibility. In the future, this capability will be in even greater demand as space platforms become more modular making on-orbit servicing, repair and reconfiguration routine. To assist crew, NASA is developing Robonaut, an anthropomorphic robot with human sized arms and hands that can work with many of the same interfaces designed for the space suited astronaut. Recently Robonaut has been used to investigate techniques for automated assembly, disassembly, and repair of space platforms. The current work focuses on techniques to reconfigure a modular truss system representative of the tasks necessary to convert a space solar power tug to a lunar orbiting solar power station in support of lunar exploration missions. An overview of these activities is given, detailing the assembly sequence and the infrastructure used by Robonaut to perform the reconfiguration operations. Advances in Robonaut's capabilities are described and include: a grip surface augmentation to Robonaut's gloves that provides a close approximation to the latest astronaut gloves, ensuring a secure grasp during truss coupler manipulation, and a shared control strategy that divides the Cartesian control of Robonaut's hands between the teleoperator and the robot's on-board controller to minimize human workload during constrained tasks. To support truss reconfiguration experiments, infrastructure is required to stabilize and register the structure during reconfiguration. Details on the design and operation of the infrastructure, a small fixture, are given.

  10. Thermal characteristics of poly(ethylene vinyl acetate) from 80 to 300 K

    NASA Astrophysics Data System (ADS)

    Pattanayak, S.; Bhowmick, T.

    This paper presents experimental results on thermal conductivity from 60 to 300 K and heat capacity from 80 to 300 K for poly(ethylene vinyl acetate) (EVA) having a crystallinity of 42%. Thermal conductivity increases with temperature. A deviation is observed in the region 170-210 K, where it shows a plateau. The variation of thermal conductivity (K) before and after the plateau is expressed by two empirical equations: K = ATm from 60 to 170 K and K = BTn from 210 to 300 K, where A = 9.437 × 10 -10W cm-1K-(m + 1), B = 1.082 × 10 -10W cm -1 K -(n + 1), m = 3.115 and n = 0.50, determined from experimental values. There is a considerable difference in the rates of change of thermal conductivity in the two regions. Below 100 K the change is almost negligible. The heat capacity also increases with temperature and from 170 to 210 K it shoots up and drops down again to match the nonlinear variation of thermal conductivity. A maximum is observed at 195 K, indicating a transition temperature. The change of heat capacity of EVA is well represented by the empirical equation C = DTP where D = 0.0575 J g -1 K -( p + 1) and p = 0.73. The change of C/T3 is 0.023 J g -1 K -4 between 80 and 170 K and 0.00187 J g -1 K -4 between 210 and 300 K. This variation is found to follow the Debye rule when the temperature is > 270 K. The measured heat capacity and thermal conductivity of EVA are compared with those of polyethylene (PE) and polytetrafluoroethylene (PTFE).

  11. Diffusion of copolymers composed of monomers with drastically different friction factors in copolymer/homopolymer blends

    NASA Astrophysics Data System (ADS)

    Duranty, Edward R.; Baschnagel, Jörg; Dadmun, Mark

    2017-02-01

    Copolymers are commonly used as interface modifiers that allow for the compatibilization of polymer components in a blend. For copolymers to function as a compatibilizer, they must diffuse through the matrix of the blend to the interface between the two blend components. The diffusivity of a copolymer in a blend matrix therefore becomes important in determining good candidates for use as compatibilizers. In this work, coarse-grained Monte Carlo simulations using the bond fluctuation model modified with an overlap penalty have been developed to study the diffusive behavior of PS/PMMA random copolymers in a PMMA homopolymer blend. The simulations vary the connectivity between different monomers, the thermodynamic interactions between the monomers which manifest within a chain, and between copolymer and homopolymer matrix and define the monomer friction coefficient of each component independently, allowing for the determination of the combined effect of these parameters on copolymer chain diffusion. The results of this work indicate that PS-r-PMMA copolymer diffusion is not linearly dependent on the copolymer composition on a logarithmic scale, but its diffusion is a balance of the kinetics governed by the dominant motion of the faster styrene monomers and thermodynamics, which are governed by the concentration of styrene monomer within a given monomer's local volume.

  12. Acetate fuels the cancer engine.

    PubMed

    Lyssiotis, Costas A; Cantley, Lewis C

    2014-12-18

    Cancer cells have distinctive nutrient demands to fuel growth and proliferation, including the disproportionate use of glucose, glutamine, and fatty acids. Comerford et al. and Mashimo et al. now demonstrate that several types of cancer are avid consumers of acetate, which facilitates macromolecular biosynthesis and histone modification.

  13. Conversion of IVA Human Computer Model to EVA Use and Evaluation and Comparison of the Result to Existing EVA Models

    NASA Technical Reports Server (NTRS)

    Hamilton, George S.; Williams, Jermaine C.

    1998-01-01

    This paper describes the methods, rationale, and comparative results of the conversion of an intravehicular (IVA) 3D human computer model (HCM) to extravehicular (EVA) use and compares the converted model to an existing model on another computer platform. The task of accurately modeling a spacesuited human figure in software is daunting: the suit restricts the human's joint range of motion (ROM) and does not have joints collocated with human joints. The modeling of the variety of materials needed to construct a space suit (e. g. metal bearings, rigid fiberglass torso, flexible cloth limbs and rubber coated gloves) attached to a human figure is currently out of reach of desktop computer hardware and software. Therefore a simplified approach was taken. The HCM's body parts were enlarged and the joint ROM was restricted to match the existing spacesuit model. This basic approach could be used to model other restrictive environments in industry such as chemical or fire protective clothing. In summary, the approach provides a moderate fidelity, usable tool which will run on current notebook computers.

  14. Origins of blood acetate in the rat.

    PubMed Central

    Buckley, B M; Williamson, D H

    1977-01-01

    A novel enzymimc cycling assay for the determination of acetate in biological material is described. Measurements of the acetate concentration in blood and liver samples from rats of various ages and nutritional states with this assay are reported. The contribution of the intestine, the liver and the rest of the body to maintaining the concentration of acetate in the circulation is examined. Evidence is presented that the gut flora constitute the main source of acetate in blood of fed adult rats, though endogenous production of acetate is of significance in other situations. The streptozotocin-diabetic rat has an elevated blood acetate concentration. PMID:597244

  15. Polyhydroxyalkanoate copolymers from forest biomass.

    PubMed

    Keenan, Thomas M; Nakas, James P; Tanenbaum, Stuart W

    2006-07-01

    The potential for the use of woody biomass in poly-beta-hydroxyalkanoate (PHA) biosynthesis is reviewed. Based on previously cited work indicating incorporation of xylose or levulinic acid (LA) into PHAs by several bacterial strains, we have initiated a study for exploring bioconversion of forest resources to technically relevant copolymers. Initially, PHA was synthesized in shake-flask cultures of Burkholderia cepacia grown on 2.2% (w/v) xylose, periodically amended with varying concentrations of levulinic acid [0.07-0.67% (w/v)]. Yields of poly(beta-hydroxybutyrate-co-beta-hydroxyvalerate) [P(3HB-co-3HV)] from 1.3 to 4.2 g/l were obtained and could be modulated to contain from 1.0 to 61 mol% 3-hydroxyvalerate (3HV), as determined by 1H and 13C NMR analyses. No evidence for either the 3HB or 4HV monomers was found. Characterization of these P(3HB-co-3HV) samples, which ranged in molecular mass (viscometric, Mv) from 511-919 kDa, by differential scanning calorimetry and thermogravimetric analyses (TGA) provided data which were in agreement for previously reported P(3HB-co-3HV) copolymers. For these samples, it was noted that melting temperature (Tm) and glass transition temperature (Tg) decreased as a function of 3HVcontent, with Tm demonstrating a pseudoeutectic profile as a function of mol% 3HV content. In order to extend these findings to the use of hemicellulosic process streams as an inexpensive carbon source, a detoxification procedure involving sequential overliming and activated charcoal treatments was developed. Two such detoxified process hydrolysates (NREL CF: aspen and CESF: maple) were each fermented with appropriate LA supplementation. For the NREL CF hydrolysate-based cultures amended with 0.25-0.5% LA, P(3HB-co-3HV) yields, PHA contents (PHA as percent of dry biomass), and mol% 3HV compositions of 2.0 g/l, 40% (w/w), and 16-52 mol% were obtained, respectively. Similarly, the CESF hydrolysate-based shake-flask cultures yielded 1.6 g/l PHA, 39% (w

  16. Custom Unit Pump Development for the EVA PLSS

    NASA Technical Reports Server (NTRS)

    Schuller, Michael; Kurwitz, Cable; Little, Frank; Oinuma, Ryoji; Larsen, Ben; Goldman, Jeff; Reinis, Filip; Trevino, Luis

    2010-01-01

    This paper describes the effort by the Texas Engineering Experiment Station (TEES) and Honeywell for NASA to design and test a pre-flight prototype pump for use in the Extra-vehicular activity (EVA) portable life support subsystem (PLSS). Major design decisions were driven by the need to reduce the pump s mass, power, and volume compared to the existing PLSS pump. In addition, the pump must accommodate a much wider range of abnormal conditions than the existing pump, including vapor/gas bubbles and increased pressure drop when employed to cool two suits simultaneously. A positive displacement, external gear type pump was selected because it offers the most compact and highest efficiency solution over the required range of flow rates and pressure drops. An additional benefit of selecting a gear pump design is that it is self priming and capable of ingesting non-condensable gas without becoming air locked. The chosen pump design consists of a 28 V DC, brushless, seal-less, permanent magnet motor driven, external gear pump that utilizes a Honeywell development that eliminates the need for magnetic coupling. The pump design was based on existing Honeywell designs, but incorporated features specifically for the PLSS application, including all of the key features of the flight pump. Testing at TEES verified that the pump meets the design requirements for range of flow rates, pressure drop, power consumption, working fluid temperature, operating time, gas ingestion, and restart capability under both ambient and vacuum conditions. The pump operated at 40 to 240 lbm/hr flow rate, 35 to 100 oF pump temperature, and 5 to 10 psid pressure rise. Power consumption of the pump controller at the nominal operating point in both ambient and vacuum conditions was 9.5 W, which was less than the 12 W predicted. Gas ingestion capabilities were tested by injecting 100 cc of air into the fluid line; the pump operated normally throughout this test.

  17. Easy Volcanic Aerosol (EVA v1.0): an idealized forcing generator for climate simulations

    NASA Astrophysics Data System (ADS)

    Toohey, Matthew; Stevens, Bjorn; Schmidt, Hauke; Timmreck, Claudia

    2016-11-01

    Stratospheric sulfate aerosols from volcanic eruptions have a significant impact on the Earth's climate. To include the effects of volcanic eruptions in climate model simulations, the Easy Volcanic Aerosol (EVA) forcing generator provides stratospheric aerosol optical properties as a function of time, latitude, height, and wavelength for a given input list of volcanic eruption attributes. EVA is based on a parameterized three-box model of stratospheric transport and simple scaling relationships used to derive mid-visible (550 nm) aerosol optical depth and aerosol effective radius from stratospheric sulfate mass. Precalculated look-up tables computed from Mie theory are used to produce wavelength-dependent aerosol extinction, single scattering albedo, and scattering asymmetry factor values. The structural form of EVA and the tuning of its parameters are chosen to produce best agreement with the satellite-based reconstruction of stratospheric aerosol properties following the 1991 Pinatubo eruption, and with prior millennial-timescale forcing reconstructions, including the 1815 eruption of Tambora. EVA can be used to produce volcanic forcing for climate models which is based on recent observations and physical understanding but internally self-consistent over any timescale of choice. In addition, EVA is constructed so as to allow for easy modification of different aspects of aerosol properties, in order to be used in model experiments to help advance understanding of what aspects of the volcanic aerosol are important for the climate system.

  18. Development of an Extra-vehicular (EVA) Infrared (IR) Camera Inspection System

    NASA Technical Reports Server (NTRS)

    Gazarik, Michael; Johnson, Dave; Kist, Ed; Novak, Frank; Antill, Charles; Haakenson, David; Howell, Patricia; Pandolf, John; Jenkins, Rusty; Yates, Rusty

    2006-01-01

    Designed to fulfill a critical inspection need for the Space Shuttle Program, the EVA IR Camera System can detect crack and subsurface defects in the Reinforced Carbon-Carbon (RCC) sections of the Space Shuttle s Thermal Protection System (TPS). The EVA IR Camera performs this detection by taking advantage of the natural thermal gradients induced in the RCC by solar flux and thermal emission from the Earth. This instrument is a compact, low-mass, low-power solution (1.2cm3, 1.5kg, 5.0W) for TPS inspection that exceeds existing requirements for feature detection. Taking advantage of ground-based IR thermography techniques, the EVA IR Camera System provides the Space Shuttle program with a solution that can be accommodated by the existing inspection system. The EVA IR Camera System augments the visible and laser inspection systems and finds cracks and subsurface damage that is not measurable by the other sensors, and thus fills a critical gap in the Space Shuttle s inspection needs. This paper discusses the on-orbit RCC inspection measurement concept and requirements, and then presents a detailed description of the EVA IR Camera System design.

  19. Comparison Of Human Modelling Tools For Efficiency Of Prediction Of EVA Tasks

    NASA Technical Reports Server (NTRS)

    Dischinger, H. Charles, Jr.; Loughead, Tomas E.

    1998-01-01

    Construction of the International Space Station (ISS) will require extensive extravehicular activity (EVA, spacewalks), and estimates of the actual time needed continue to rise. As recently as September, 1996, the amount of time to be spent in EVA was believed to be about 400 hours, excluding spacewalks on the Russian segment. This estimate has recently risen to over 1100 hours, and it could go higher before assembly begins in the summer of 1998. These activities are extremely expensive and hazardous, so any design tools which help assure mission success and improve the efficiency of the astronaut in task completion can pay off in reduced design and EVA costs and increased astronaut safety. The tasks which astronauts can accomplish in EVA are limited by spacesuit mobility. They are therefore relatively simple, from an ergonomic standpoint, requiring gross movements rather than time motor skills. The actual tasks include driving bolts, mating and demating electric and fluid connectors, and actuating levers; the important characteristics to be considered in design improvement include the ability of the astronaut to see and reach the item to be manipulated and the clearance required to accomplish the manipulation. This makes the tasks amenable to simulation in a Computer-Assisted Design (CAD) environment. For EVA, the spacesuited astronaut must have his or her feet attached on a work platform called a foot restraint to obtain a purchase against which work forces may be actuated. An important component of the design is therefore the proper placement of foot restraints.

  20. Development of an extra-vehicular (EVA) infrared (IR) camera inspection system

    NASA Astrophysics Data System (ADS)

    Gazarik, Michael; Johnson, Dave; Kist, Ed; Novak, Frank; Antill, Charles; Haakenson, David; Howell, Patricia; Pandolf, John; Jenkins, Rusty; Yates, Rusty; Stephan, Ryan; Hawk, Doug; Amoroso, Michael

    2006-04-01

    Designed to fulfill a critical inspection need for the Space Shuttle Program, the EVA IR Camera System can detect crack and subsurface defects in the Reinforced Carbon-Carbon (RCC) sections of the Space Shuttle's Thermal Protection System (TPS). The EVA IR Camera performs this detection by taking advantage of the natural thermal gradients induced in the RCC by solar flux and thermal emission from the Earth. This instrument is a compact, low-mass, low-power solution (1.2cm3, 1.5kg, 5.0W) for TPS inspection that exceeds existing requirements for feature detection. Taking advantage of ground-based IR thermography techniques, the EVA IR Camera System provides the Space Shuttle program with a solution that can be accommodated by the existing inspection system. The EVA IR Camera System augments the visible and laser inspection systems and finds cracks and subsurface damage that is not measurable by the other sensors, and thus fills a critical gap in the Space Shuttle's inspection needs. This paper discusses the on-orbit RCC inspection measurement concept and requirements, and then presents a detailed description of the EVA IR Camera System design.

  1. Biosensors for EVA: Muscle Oxygen and pH During Walking, Running and Simulated Reduced Gravity

    NASA Technical Reports Server (NTRS)

    Lee, S. M. C.; Ellerby, G.; Scott, P.; Stroud, L.; Norcross, J.; Pesholov, B.; Zou, F.; Gernhardt, M.; Soller, B.

    2009-01-01

    During lunar excursions in the EVA suit, real-time measurement of metabolic rate is required to manage consumables and guide activities to ensure safe return to the base. Metabolic rate, or oxygen consumption (VO2), is normally measured from pulmonary parameters but cannot be determined with standard techniques in the oxygen-rich environment of a spacesuit. Our group developed novel near infrared spectroscopic (NIRS) methods to calculate muscle oxygen saturation (SmO2), hematocrit, and pH, and we recently demonstrated that we can use our NIRS sensor to measure VO2 on the leg during cycling. Our NSBRI-funded project is looking to extend this methodology to examine activities which more appropriately represent EVA activities, such as walking and running and to better understand factors that determine the metabolic cost of exercise in both normal and lunar gravity. Our 4 year project specifically addresses risk: ExMC 4.18: Lack of adequate biomedical monitoring capability for Constellation EVA Suits and EPSP risk: Risk of compromised EVA performance and crew health due to inadequate EVA suit systems.

  2. Initiator Effects in Reactive Extrusion of Starch Graft Copolymers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Graft copolymers of starch with water-soluble polymers such as polyacrylamide have potential applications including hydrogels, superabsorbents, and thickening agents. Reactive extrusion is a rapid, continuous method for production of starch graft copolymers with high reaction and grafting efficienc...

  3. Hydrogen-bonded aggregates in precise acid copolymers

    SciTech Connect

    Lueth, Christopher A.; Bolintineanu, Dan S.; Stevens, Mark J. Frischknecht, Amalie L.

    2014-02-07

    We perform atomistic molecular dynamics simulations of melts of four precise acid copolymers, two poly(ethylene-co-acrylic acid) (PEAA) copolymers, and two poly(ethylene-co-sulfonic acid) (PESA) copolymers. The acid groups are spaced by either 9 or 21 carbons along the polymer backbones. Hydrogen bonding causes the acid groups to form aggregates. These aggregates give rise to a low wavevector peak in the structure factors, in agreement with X-ray scattering data for the PEAA materials. The structure factors for the PESA copolymers are very similar to those for the PEAA copolymers, indicating a similar distance between aggregates which depends on the spacer length but not on the nature of the acid group. The PEAA copolymers are found to form more dimers and other small aggregates than do the PESA copolymers, while the PESA copolymers have both more free acid groups and more large aggregates.

  4. Soluplus graft copolymer: potential novel carrier polymer in electrospinning of nanofibrous drug delivery systems for wound therapy.

    PubMed

    Paaver, Urve; Tamm, Ingrid; Laidmäe, Ivo; Lust, Andres; Kirsimäe, Kalle; Veski, Peep; Kogermann, Karin; Heinämäki, Jyrki

    2014-01-01

    Electrospinning is an effective method in preparing polymeric nanofibrous drug delivery systems (DDSs) for topical wound healing and skin burn therapy applications. The aim of the present study was to investigate a new synthetic graft copolymer (Soluplus) as a hydrophilic carrier polymer in electrospinning of nanofibrous DDSs. Soluplus (polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (PCL-PVAc-PEG)) was applied in the nonwoven nanomats loaded with piroxicam (PRX) as a poorly water-soluble drug. Raman spectroscopy, X-ray powder diffraction, differential scanning calorimetry, and scanning electron microscopy (SEM) were used in the physical characterization of nanofibrous DDSs. According to the SEM results, the drug-loaded PCL-PVAc-PEG nanofibers were circular in cross-section with an average diameter ranging from 500 nm up to 2  µm. Electrospinning stabilized the amorphous state of PRX. In addition, consistent and sustained-release profile was achieved with the present nanofibrous DDSs at the physiologically relevant temperature and pH applicable in wound healing therapy. In conclusion, electrospinning can be used to prepare nanofibrous DDSs of PCL-PVAc-PEG graft copolymer (Soluplus) and to stabilize the amorphous state of a poorly water-soluble PRX. The use of this synthetic graft copolymer can open new options to formulate nanofibrous DDSs for wound healing.

  5. Cellulose ester-graft-poly(epsilon-caprolactone): effects of copolymer composition and intercomponent miscibility on the enzymatic hydrolysis behavior.

    PubMed

    Kusumi, Ryosuke; Lee, Seung-Hwan; Teramoto, Yoshikuni; Nishio, Yoshiyuki

    2009-10-12

    Enzymatic hydrolysis was conducted with Pseudomonas lipase for film samples of graft copolymers of cellulose acetate (CA) and butyrate (CB) with poly(epsilon-caprolactone) (PCL), CA-g-PCL, and CB-g-PCL, respectively. The two trunk polymers CA and CB, both having the degree of acyl substitution (DS) of >2, are respectively immiscible and miscible with PCL. A hindrance effect of the cellulose ester trunks on the enzymatic attack to the PCL component was observed for the two copolymer series; the situation was more conspicuous in the use of CB trunks. After the selective hydrolytic degradation of the PCL component, a topographical study by AFM revealed that the CA and CB constituents as residues formed a protuberant structure on the surface of the respective film specimens. The altitude and regularity of the protuberances were variant depending on the initial copolymer composition. In a phase-imaging mode of AFM, a hydrolyzed film of CA-g-PCL with an extremely low graft-density (acetyl DS > 2.95) showed particularly larger CA domains of >25 nm in diameter. The domain sizes were in accordance with a heterogeneity scale in the original intercomponent mixing state estimated by (1)H spin-lattice relaxation time (T(1)(H)) measurements in solid-state (13)C NMR spectroscopy. The present results demonstrate a high potential in application of the PCL-grafted cellulosic copolymers as spatiotemporally biodegradation-controllable materials.

  6. Carbon-isotopic analysis of dissolved acetate

    NASA Technical Reports Server (NTRS)

    Gelwicks, J. T.; Hayes, J. M.

    1990-01-01

    Heating of dried, acetate-containing solids together with oxalic acid dihydrate conveniently releases acetic acid for purification by gas chromatography. For determination of the carbon-isotopic composition of total acetate, the acetate-containing zone of the chromatographic effluent can be routed directly to a combustion furnace coupled to a vacuum system allowing recovery, purification, and packaging of CO2 for mass-spectrometric analysis. For analysis of methyl carbon, acetic acid can be cryogenically trapped from the chromatographic effluent, then transferred to a tube containing excess NaOH. The tube is evacuated, sealed, and heated to 500 degrees C to produce methane by pyrolysis of sodium acetate. Subsequent combustion of the methane allows determination of the 13C content at the methyl position in the parent acetate. With typical blanks, the standard deviation of single analyses is less than 0.4% for acetate samples larger than 5 micromoles. A full treatment of uncertainties is outlined.

  7. Ozone decomposition in aqueous acetate solutions

    SciTech Connect

    Sehested, K.; Holcman, J.; Bjergbakke, E.; Hart, E.J.

    1987-01-01

    The acetate radical ion reacts with ozone with a rate constant of k = (1.5 +/- 0.5) x 10Z dmT mol s . The products from this reaction are CO2, HCHO, and O2 . By subsequent reaction of the peroxy radical with ozone the acetate radical ion is regenerated through the OH radical. A chain decomposition of ozone takes place. It terminates when the acetate radical ion reacts with oxygen forming the unreactive peroxy acetate radical. The chain is rather short as oxygen is developed, as a result of the ozone consumption. The inhibiting effect of acetate on the ozone decay is rationalized by OH scavenging by acetate and successive reaction of the acetate radical ion with oxygen. Some products from the bimolecular disappearance of the peroxy acetate radicals, however, react further with ozone, reducing the effectiveness of the stabilization.

  8. Carbon-isotopic analysis of dissolved acetate.

    PubMed

    Gelwicks, J T; Hayes, J M

    1990-01-01

    Heating of dried, acetate-containing solids together with oxalic acid dihydrate conveniently releases acetic acid for purification by gas chromatography. For determination of the carbon-isotopic composition of total acetate, the acetate-containing zone of the chromatographic effluent can be routed directly to a combustion furnace coupled to a vacuum system allowing recovery, purification, and packaging of CO2 for mass-spectrometric analysis. For analysis of methyl carbon, acetic acid can be cryogenically trapped from the chromatographic effluent, then transferred to a tube containing excess NaOH. The tube is evacuated, sealed, and heated to 500 degrees C to produce methane by pyrolysis of sodium acetate. Subsequent combustion of the methane allows determination of the 13C content at the methyl position in the parent acetate. With typical blanks, the standard deviation of single analyses is less than 0.4% for acetate samples larger than 5 micromoles. A full treatment of uncertainties is outlined.

  9. Charge Transport in Conjugated Block Copolymers

    NASA Astrophysics Data System (ADS)

    Smith, Brandon; Le, Thinh; Lee, Youngmin; Gomez, Enrique

    Interest in conjugated block copolymers for high performance organic photovoltaic applications has increased considerably in recent years. Polymer/fullerene mixtures for conventional bulk heterojunction devices, such as P3HT:PCBM, are severely limited in control over interfaces and domain length scales. In contrast, microphase separated block copolymers self-assemble to form lamellar morphologies with alternating electron donor and acceptor domains, thereby maximizing electronic coupling and local order at interfaces. Efficiencies as high as 3% have been reported in solar cells for one block copolymer, P3HT-PFTBT, but the details concerning charge transport within copolymers have not been explored. To fill this gap, we probed the transport characteristics with thin-film transistors. Excellent charge mobility values for electron transport have been observed on aluminum source and drain contacts in a bottom gate, bottom contact transistor configuration. Evidence of high mobility in ordered PFTBT phases has also been obtained following thermal annealing. The insights gleaned from our investigation serve as useful guideposts, revealing the significance of the interplay between charge mobility, interfacial order, and optimal domain size in organic block copolymer semiconductors.

  10. 21 CFR 184.1721 - Sodium acetate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium acetate. 184.1721 Section 184.1721 Food and....1721 Sodium acetate. (a) Sodium acetate (C2H3O2Na, CAS Reg. No. 127-09-3 or C2H3O2Na·3H2O, CAS Reg. No. 6131-90-4) is the sodium salt of acetic acid and occurs naturally in plant and animal tissues....

  11. Synthesis of comb-like copolymers from renewable resources: Itaconic anhydride, stearyl methacrylate and lactic acid

    NASA Astrophysics Data System (ADS)

    Shang, Shurui

    The synthesis and properties of comb-like copolymers and ionomers derived from renewable resources: itaconic anhydride (ITA), stearyl methacrylate (SM) and lactic acid (LA) are described. The copolymers based on ITA and SM (ITA-SM) were nearly random with a slight alternating tendency. The copolymers exhibited a nanophase-separated morphology, with the stearate side-chains forming a bilayer, semi-crystalline structure. The crystalline side-chains suppressed molecular motion of the main-chain, so that a glass transition temperature (Tg) was not resolved unless the ITA concentration was sufficiently high so that Tg > the melting point (Tm). The softening point and modulus of the copolymers increased with the increasing ITA concentration, but the thermal stability decreased. The ITA moiety along the main chain of the copolymers was neutralized with metal acetates to produce Na-, Ca- and Zn- random ionomers with comb-like architectures. In general, the incorporation of the ionic groups increased the Tg and suppressed the crystallinity of the side-chain packing. Ionomers with high SM side-chain density had two competing driving forces for self-assembled nano-phase separation: ionic aggregation and side-chain crystalline packing. Upon neutralization, a morphological transition from semi-crystalline lamella to spherical ionic aggregation was observed by small angle X-ray scattering (SAXS) analysis and transmission electron microscopy (TEM). Thermomechanical analysis revealed an increasing resistance to penetration deformation with an increasing degree of neutralization and an apparent rubbery plateau was observed above Tg. A controlled transesterification of PLA in glassware was an effective way to prepare a methacrylate functionalized PLA macromonomer with controlled molecular weight, which was used to synthesize a variety of copolymers. The copolymerization of this functionalized PLA macromonomer with ITA totally suppressed the side-chain crystallinity for the PLA chain

  12. 21 CFR 177.1060 - n-Alkylglutarimide/acrylic copolymers.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true n-Alkylglutarimide/acrylic copolymers. 177.1060... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1060 n-Alkylglutarimide/acrylic copolymers. n-Alkylglutarimide/acrylic copolymers identified in this section may be safely used as...

  13. 21 CFR 177.1060 - n-Alkylglutarimide/acrylic copolymers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false n-Alkylglutarimide/acrylic copolymers. 177.1060... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1060 n-Alkylglutarimide/acrylic copolymers. n-Alkylglutarimide/acrylic copolymers identified in this section may be safely used as...

  14. 21 CFR 177.1060 - n-Alkylglutarimide/acrylic copolymers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false n-Alkylglutarimide/acrylic copolymers. 177.1060... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1060 n-Alkylglutarimide/acrylic copolymers. n-Alkylglutarimide/acrylic copolymers identified in this section may be safely used as...

  15. 21 CFR 175.210 - Acrylate ester copolymer coating.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Acrylate ester copolymer coating. 175.210 Section... COATINGS Substances for Use as Components of Coatings § 175.210 Acrylate ester copolymer coating. Acrylate ester copolymer coating may safely be used as a food-contact surface of articles intended for...

  16. 21 CFR 175.210 - Acrylate ester copolymer coating.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Acrylate ester copolymer coating. 175.210 Section... COATINGS Substances for Use as Components of Coatings § 175.210 Acrylate ester copolymer coating. Acrylate ester copolymer coating may safely be used as a food-contact surface of articles intended for...

  17. 21 CFR 175.210 - Acrylate ester copolymer coating.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Acrylate ester copolymer coating. 175.210 Section... COATINGS Substances for Use as Components of Coatings § 175.210 Acrylate ester copolymer coating. Acrylate ester copolymer coating may safely be used as a food-contact surface of articles intended for...

  18. 21 CFR 175.210 - Acrylate ester copolymer coating.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Acrylate ester copolymer coating. 175.210 Section... COATINGS Substances for Use as Components of Coatings § 175.210 Acrylate ester copolymer coating. Acrylate ester copolymer coating may safely be used as a food-contact surface of articles intended for...

  19. Structure Confirmation and Properties of Poly(Dimethylsiloxaneco-diethylsiloxane) Copolymer

    NASA Astrophysics Data System (ADS)

    Gao, Li-Juan; Ma, De-Peng; Feng, Sheng-Yu

    2016-05-01

    High molecular weight poly (dimethylsiloxane-co-diethylsiloxane) (PMES) copolymer was synthesized by anionic ring opening polymerization. Its composition and structures was determined by 29Si NMR spectroscopy. A random microstructure of copolymer was observed in the 29Si NMR spectrum. Further, PMES was characterized by GPC and DSC. The results show that PMES is crystallization-free copolymer with low glass transition temperatures.

  20. 21 CFR 177.1820 - Styrene-maleic anhydride copolymers.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Styrene-maleic anhydride copolymers. 177.1820... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1820 Styrene-maleic anhydride copolymers. Styrene-maleic anhydride copolymers identified in paragraph (a) of this section may be...

  1. pH-sensitive methacrylic copolymers and the production thereof

    SciTech Connect

    Mallapragada, Surya K.; Anderson, Brian C.; Bloom, Paul D.; Sheares Ashby, Valerie V.

    2007-01-09

    The present invention provides novel multi-functional methacrylic copolymers that exhibit cationic pH-sensitive behavior as well as good water solubility under acidic conditions. The copolymers are constructed from tertiary amine methacrylates and poly(ethylene glycol) containing methacrylates. The copolymers are useful as gene vectors, pharmaceutical carriers, and in protein separation applications.

  2. pH-sensitive methacrylic copolymers and the production thereof

    DOEpatents

    Mallapragada, Surya K.; Anderson, Brian C.; Bloom, Paul D.; Sheares Ashby, Valerie V.

    2006-02-14

    The present invention provides novel multi-functional methacrylic copolymers that exhibit cationic pH-sensitive behavior as well as good water solubility under acidic conditions. The copolymers are constructed from tertiary amine methacrylates and poly(ethylene glycol) containing methacrylates. The copolymers are useful as gene vectors, pharmaceutical carriers, and in protein separation applications.

  3. 21 CFR 177.1312 - Ethylene-carbon monoxide copolymers.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ethylene-carbon monoxide copolymers. 177.1312... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1312 Ethylene-carbon monoxide copolymers. The ethylene-carbon monoxide copolymers identified in paragraph (a) of this section may be...

  4. 21 CFR 177.1312 - Ethylene-carbon monoxide copolymers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Ethylene-carbon monoxide copolymers. 177.1312... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1312 Ethylene-carbon monoxide copolymers. The ethylene-carbon monoxide copolymers identified in paragraph (a) of this section may be...

  5. 21 CFR 177.1312 - Ethylene-carbon monoxide copolymers.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Ethylene-carbon monoxide copolymers. 177.1312... Use Food Contact Surfaces § 177.1312 Ethylene-carbon monoxide copolymers. The ethylene-carbon monoxide... of this section, ethylene-carbon monoxide copolymers (CAS Reg. No. 25052-62-4) consist of the...

  6. 21 CFR 177.1312 - Ethylene-carbon monoxide copolymers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Ethylene-carbon monoxide copolymers. 177.1312... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1312 Ethylene-carbon monoxide copolymers. The ethylene-carbon monoxide copolymers identified in paragraph (a) of this section may be...

  7. 21 CFR 177.1312 - Ethylene-carbon monoxide copolymers.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Ethylene-carbon monoxide copolymers. 177.1312... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1312 Ethylene-carbon monoxide copolymers. The ethylene-carbon monoxide copolymers identified in paragraph (a) of this section may be...

  8. 40 CFR 721.484 - Fluorinated acrylic copolymer (generic name).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Fluorinated acrylic copolymer (generic... Specific Chemical Substances § 721.484 Fluorinated acrylic copolymer (generic name). (a) Chemical substance... fluorinated acrylic copolymer (PMN P-95-1208) is subject to reporting under this section for the...

  9. 40 CFR 721.484 - Fluorinated acrylic copolymer (generic name).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Fluorinated acrylic copolymer (generic... Specific Chemical Substances § 721.484 Fluorinated acrylic copolymer (generic name). (a) Chemical substance... fluorinated acrylic copolymer (PMN P-95-1208) is subject to reporting under this section for the...

  10. 21 CFR 177.1060 - n-Alkylglutarimide/acrylic copolymers.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false n-Alkylglutarimide/acrylic copolymers. 177.1060... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1060 n-Alkylglutarimide/acrylic copolymers. n-Alkylglutarimide/acrylic copolymers identified in this section may be safely used as...

  11. 21 CFR 177.1320 - Ethylene-ethyl acrylate copolymers.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Ethylene-ethyl acrylate copolymers. 177.1320... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1320 Ethylene-ethyl acrylate copolymers. Ethylene-ethyl acrylate copolymers may be safely used to produce packaging materials,...

  12. 21 CFR 177.1950 - Vinyl chloride-ethylene copolymers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Vinyl chloride-ethylene copolymers. 177.1950... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1950 Vinyl chloride-ethylene copolymers. The vinyl chloride-ethylene copolymers identified in paragraph (a) of this section may be...

  13. 21 CFR 177.1950 - Vinyl chloride-ethylene copolymers.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Vinyl chloride-ethylene copolymers. 177.1950... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1950 Vinyl chloride-ethylene copolymers. The vinyl chloride-ethylene copolymers identified in paragraph (a) of this section may be...

  14. 21 CFR 177.1950 - Vinyl chloride-ethylene copolymers.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Vinyl chloride-ethylene copolymers. 177.1950... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1950 Vinyl chloride-ethylene copolymers. The vinyl chloride-ethylene copolymers identified in paragraph (a) of this section may be...

  15. 21 CFR 177.1310 - Ethylene-acrylic acid copolymers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Ethylene-acrylic acid copolymers. 177.1310 Section... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1310 Ethylene-acrylic acid copolymers. The ethylene-acrylic acid copolymers identified in paragraph (a) of this section may be...

  16. 21 CFR 177.1950 - Vinyl chloride-ethylene copolymers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Vinyl chloride-ethylene copolymers. 177.1950... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1950 Vinyl chloride-ethylene copolymers. The vinyl chloride-ethylene copolymers identified in paragraph (a) of this section may be...

  17. 21 CFR 177.1320 - Ethylene-ethyl acrylate copolymers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Ethylene-ethyl acrylate copolymers. 177.1320... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1320 Ethylene-ethyl acrylate copolymers. Ethylene-ethyl acrylate copolymers may be safely used to produce packaging materials,...

  18. 21 CFR 177.1320 - Ethylene-ethyl acrylate copolymers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Ethylene-ethyl acrylate copolymers. 177.1320... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1320 Ethylene-ethyl acrylate copolymers. Ethylene-ethyl acrylate copolymers may be safely used to produce packaging materials,...

  19. 21 CFR 177.1310 - Ethylene-acrylic acid copolymers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Ethylene-acrylic acid copolymers. 177.1310 Section... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1310 Ethylene-acrylic acid copolymers. The ethylene-acrylic acid copolymers identified in paragraph (a) of this section may be...

  20. 21 CFR 177.1310 - Ethylene-acrylic acid copolymers.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ethylene-acrylic acid copolymers. 177.1310 Section... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1310 Ethylene-acrylic acid copolymers. The ethylene-acrylic acid copolymers identified in paragraph (a) of this section may be...

  1. 21 CFR 177.1310 - Ethylene-acrylic acid copolymers.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Ethylene-acrylic acid copolymers. 177.1310 Section... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1310 Ethylene-acrylic acid copolymers. The ethylene-acrylic acid copolymers identified in paragraph (a) of this section may be...

  2. 21 CFR 172.775 - Methacrylic acid-divinylbenzene copolymer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Methacrylic acid-divinylbenzene copolymer. 172.775... HUMAN CONSUMPTION Other Specific Usage Additives § 172.775 Methacrylic acid-divinylbenzene copolymer. Methacrylic acid-divinylbenzene copolymer may be safely used in food in accordance with the...

  3. 21 CFR 172.775 - Methacrylic acid-divinylbenzene copolymer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Methacrylic acid-divinylbenzene copolymer. 172.775... HUMAN CONSUMPTION Other Specific Usage Additives § 172.775 Methacrylic acid-divinylbenzene copolymer. Methacrylic acid-divinylbenzene copolymer may be safely used in food in accordance with the...

  4. 21 CFR 172.775 - Methacrylic acid-divinylbenzene copolymer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Methacrylic acid-divinylbenzene copolymer. 172.775... HUMAN CONSUMPTION Other Specific Usage Additives § 172.775 Methacrylic acid-divinylbenzene copolymer. Methacrylic acid-divinylbenzene copolymer may be safely used in food in accordance with the...

  5. 21 CFR 172.775 - Methacrylic acid-divinylbenzene copolymer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Methacrylic acid-divinylbenzene copolymer. 172.775... Additives § 172.775 Methacrylic acid-divinylbenzene copolymer. Methacrylic acid-divinylbenzene copolymer may... produced by the polymerization of methacrylic acid and divinylbenzene. The divinylbenzene functions as...

  6. 21 CFR 582.1721 - Sodium acetate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Sodium acetate. 582.1721 Section 582.1721 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1721 Sodium acetate. (a) Product. Sodium acetate. (b) Conditions of use. This substance is...

  7. 21 CFR 582.1721 - Sodium acetate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Sodium acetate. 582.1721 Section 582.1721 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1721 Sodium acetate. (a) Product. Sodium acetate. (b) Conditions of use. This substance is...

  8. 21 CFR 582.1721 - Sodium acetate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Sodium acetate. 582.1721 Section 582.1721 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1721 Sodium acetate. (a) Product. Sodium acetate. (b) Conditions of use. This substance is...

  9. 21 CFR 582.1721 - Sodium acetate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Sodium acetate. 582.1721 Section 582.1721 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1721 Sodium acetate. (a) Product. Sodium acetate. (b) Conditions of use. This substance is...

  10. 21 CFR 582.1721 - Sodium acetate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Sodium acetate. 582.1721 Section 582.1721 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1721 Sodium acetate. (a) Product. Sodium acetate. (b) Conditions of use. This substance is...

  11. 21 CFR 582.1005 - Acetic acid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1005 Acetic acid. (a) Product. Acetic acid. (b) Conditions of use. This substance is...

  12. 21 CFR 582.1005 - Acetic acid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1005 Acetic acid. (a) Product. Acetic acid. (b) Conditions of use. This substance is...

  13. 21 CFR 184.1005 - Acetic acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Acetic acid. 184.1005 Section 184.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) DIRECT FOOD....1005 Acetic acid. (a) Acetic acid (C2H4O2, CAS Reg. No. 64-19-7) is known as ethanoic acid. It...

  14. 21 CFR 582.1005 - Acetic acid.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1005 Acetic acid. (a) Product. Acetic acid. (b) Conditions of use. This substance is...

  15. 21 CFR 582.1005 - Acetic acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1005 Acetic acid. (a) Product. Acetic acid. (b) Conditions of use. This substance is...

  16. 21 CFR 582.1005 - Acetic acid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1005 Acetic acid. (a) Product. Acetic acid. (b) Conditions of use. This substance is...

  17. 21 CFR 522.2476 - Trenbolone acetate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... days. (A) 140 milligrams (mg) trenbolone acetate (one implant consisting of 7 pellets, each pellet containing 20 mg trenbolone acetate) per implant dose. (B) 140 mg trenbolone acetate (one implant consisting... 29 mg tylosin tartrate) per implant dose. (ii) Indications for use. For improved feed...

  18. 21 CFR 522.2476 - Trenbolone acetate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... days. (A) 140 milligrams (mg) trenbolone acetate (one implant consisting of 7 pellets, each pellet containing 20 mg trenbolone acetate) per implant dose. (B) 140 mg trenbolone acetate (one implant consisting... 29 mg tylosin tartrate) per implant dose. (ii) Indications for use. For improved feed...

  19. Photochemistry of 2-nitrobenzylidene acetals.

    PubMed

    Sebej, Peter; Solomek, Tomás; Hroudná, L'ubica; Brancová, Pavla; Klán, Petr

    2009-11-20

    Photolysis of dihydroxy compounds (diols) protected as 2-nitrobenzylidene acetals (ONBA) and subsequent acid- or base-catalyzed hydrolysis of the 2-nitrosobenzoic acid ester intermediates result in an efficient and high-yielding release of the substrates. We investigated the scope and limitations of ONBA photochemistry and expanded upon earlier described two-step procedures to show that the protected diols of many structural varieties can also be liberated in a one-pot procedure. In view of the fact that the acetals of nonsymmetrically substituted diols are converted into one of the corresponding 2-nitrosobenzoic acid ester isomers with moderate to high regioselectivity, the mechanism of their formation was studied using various experimental techniques. The experimental data were found to be in agreement with DFT-based quantum chemical calculations that showed the preferential cleavage occurs on the acetal C-O bond in the vicinity of more electron-withdrawing (or less electron-donating) groups. The study also revealed considerable complexity in the cleavage mechanism and that the structural variations in the substrate can significantly alter the reaction pathway. This deprotection strategy was found to be also applicable for 2-thioethanol when released from the corresponding monothioacetal in the presence of a reducing agent, such as ascorbic acid.

  20. Human-Centric Teaming in a Multi-Agent EVA Assembly Task

    NASA Technical Reports Server (NTRS)

    Rehnmark, Fredrik; Currie, Nancy; Ambrose, Robert O.; Culbert, Christopher

    2004-01-01

    NASA's Human Space Flight program depends heavily on spacewalks performed by pairs of suited human astronauts. These Extra-Vehicular Activities (EVAs) are severely restricted in both duration and scope by consumables and available manpower.An expanded multi-agent EVA team combining the information-gathering and problem-solving skills of human astronauts with the survivability and physical capabilities of highly dexterous space robots is proposed. A 1-g test featuring two NASA/DARPA Robonaut systems working side-by-side with a suited human subject is conducted to evaluate human-robot teaming strategies in the context of a simulated EVA assembly task based on the STS-61B ACCESS flight experiment.