Sample records for rayon

  1. NARC Rayon Replacement Program for the RSRM Nozzle, Phase IV Qualification and Implementation Status

    NASA Technical Reports Server (NTRS)

    Haddock, M. Reed; Wendel, Gary M.; Cook, Roger V.

    2005-01-01

    The Space Shuttle NARC Rayon Replacement Program has down-selected Enka rayon as a replacement for the obsolete NARC rayon in the nozzle carbon cloth phenolic (CCP) ablative insulators. Full qualification testing of the Enka rayon-based carbon cloth phenolic is underway, including processing, thmal/structural properties, and hot-fire subscale tests. Required thermal-structural capabilities, together with confidence in erosio/char performance in simulated and subscale hot fire tests such as Wright-Patterson Air Force Base Laser Hardened Materials Evaluation Laboratory testing, NASA-MSFC 24-inch motor tests, NASA-MSFC Solid Fuel Torch - Super Sonic Blast Tube, NASA-MSFC Plasma Torch Test Bed, ATK Thiokol Forty Pound Charge and NASA-MSFC MNASA justified the testing of the new Enka-rayon candidate on full-scale static test motors. The first RSRM full-scale static test motor nozzle, fabricated using the new Enka rayon-based CCP, was successfully demonstrated in June 2004. Two additional static test motors are planned with the new Enka rayon in the next two years along with additional A-basis property characterization. Process variation or "corner-of-the-box" testing together with cured and uncured aging studies are also planned as some of the pre-flight implementation activities with 5-year cured aging studies over-lapping flight hardware fabrication.

  2. Progress Report on PICA Activities in Support of New Frontiers Missions

    NASA Technical Reports Server (NTRS)

    Stackpoole, Margaret; Venkatapathy, Ethiraj; Violette, Steve

    2017-01-01

    Phenolic Impregnated Carbon Ablator (PICA) is a TPS material that has been used in a number of previous flight missions (Stardust, MSL) and is planned for a number of future missions (OSIRIS-Rex and Mars 2020) so it has substantial flight heritage, is applicable to a wide range of missions, and is often baselined as the TPS in future NASA proposal activities. As is common with a number of TPS materials, PICA faces a supply chain issue with the rayon precursor from which the carbon fibers used in the PICA preform are derived. PICA uses a non-woven form of the rayon, which once carbonized, is used in the low-density carbon FiberForm (carbon tile) preform utilized in PICA. Current PICA uses a NASA-qualified non-domestic rayon supplier (Sniace), however the qualified supplier is no longer manufacturing the rayon materials. This activity will address PICA sustainability, by initially carbonizing the remaining stockpile of Sniace rayon precursor. A additional FiberForm manufacturing task from alternate rayon sources is also in progress.

  3. 40 CFR 414.20 - Applicability; description of the rayon fibers subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 29 2011-07-01 2009-07-01 true Applicability; description of the rayon fibers subcategory. 414.20 Section 414.20 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Rayon Fibers...

  4. 40 CFR 414.20 - Applicability; description of the rayon fibers subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 28 2010-07-01 2010-07-01 true Applicability; description of the rayon fibers subcategory. 414.20 Section 414.20 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Rayon Fibers...

  5. 40 CFR 414.20 - Applicability; description of the rayon fibers subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 30 2013-07-01 2012-07-01 true Applicability; description of the rayon fibers subcategory. 414.20 Section 414.20 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Rayon Fibers...

  6. 40 CFR 414.20 - Applicability; description of the rayon fibers subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 29 2014-07-01 2012-07-01 true Applicability; description of the rayon fibers subcategory. 414.20 Section 414.20 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Rayon Fibers...

  7. RECYCLING ZINC IN VISCOSE RAYON PLANTS BY TWO STAGE PRECIPITATION

    EPA Science Inventory

    In an EPA demonstration grant, a process for precipitating a dense sludge of high zinc assay was proven. The zinc in the sludge was recovered and recycled to the rayon manufacturing plant. This recycling of zinc was shown to have no ill effects on rayon yarn. This process greatly...

  8. NARC Rayon Replacement Program for the Space Shuttle Reusable Solid Rocket Motor Nozzle: Screening Summary

    NASA Technical Reports Server (NTRS)

    Cook, R. V.; Fairbourn, M. W.; Wendel, G. M.

    2000-01-01

    Thiokol Corporation and NASA MSFC are jointly developing a replacement for North American Rayon Corporation (NARC) Aerospace Grade Rayon (1650/720 continuous filament), the precursor for the Carbon Cloth Phenolic (CCP) ablatives used in the Space Shuttle Reusable Solid Rocket Motor (RSRM) Nozzles. NARC discontinued production of Aerospace Grade Rayon in September 1997. NASA maintains a stockpile of NARC Rayon to support RSRM production through the summer of 2005. The program plan for selection and qualification of a replacement for NARC rayon was approved in August 1998. Screening activities began in February 1999. The intent of this paper is to provide a summary of the data generated during the screening phase of the NARC Rayon Replacement Program. Twelve cellulose based fibers (rayon and lyocell) were evaluated. These fibers were supplied by three independent vendors. Many of these fibers were carbonized by two independent carbonizers. Each candidate was tested according to standard acceptance test methods at each step of the manufacturing process. Additional testing was performed with the candidate CCPS, including hot fire tests, Process studies and mechanical and thermal characterization. Six of the twelve fiber candidates tested were dropped at the conclusion of Phase 1. The reasons for the elimination of these candidates included; difficulties in processing the material in the whitegoods, carbon and CCP forms; poor composite mechanical performance; and future availability concerns. The remaining six fibers demonstrated enough promise to merit continued evaluation and optimization of the CCP fabrication process. Note: Certain CCP data falls under the restrictions of US export laws, (ITAR, etc.) and will not be included in this paper.

  9. Water requirements of the rayon- and acetate-fiber industry

    USGS Publications Warehouse

    Mussey, Orville Durey

    1957-01-01

    Water is required for several purposes in the manufacture of rayon and acetate fiber. These water requirements, as indicated by a survey of the water used by the plants operating in 1953, are both quantitative and qualitative. About 300 mgd (million gallons per day) of water was used in 1953 in the preparation of purified wood cellulose and cotton linters, the basic material from which the rayon and acetate fiber is made. An additional 620 mgd was used in the process of converting the cellulose to rayon and acetate fiber. The total, 920 mgd, is about 1 percent of the total estimated withdrawals of industrial water in the United States in 1953. The rayon- and acetate-fiber plants are scattered through eastern United States and generally are located in small towns or rural areas where there are abundant supplies of clean, soft water. Water use at a typical rayon-fiber plant was about 9 mgd, and at a typical acetate-fiber plant about 38 mgd. About 110 gallons of water was used to produce a pound of rayon fiber 32 gallons per pound was process water and the remainder was used largely for cooling in connection with power production and air conditioning. For the manufacture of a pound of acetate fiber about 170 gallons of water was used. However, the field survey on which this report is based indicated a wide range in the amount of water used per pound of product. For example, in the manufacture of viscose rayon, the maximum unit water use was 8 times the minimum unit water use. Water use in summer was about 22 percent greater than average annual use. About 8 mgd of water was consumed by evaporation in the manufacture of rayon and acetate fiber. More than 90 percent of the water used by the rayon and acetate industry was withdrawn from surface-water sources, about 8 percent from ground water, and less than 2 percent from municipal water supplies. All available analyses of the untreated waters used by the rayon and acetate industry were collected and studied. The untreated waters were generally cool, low in content of calcium and magnesium, and very low in iron and manganese. At many plants, water was obtained from more than one source, and thus had different quality characteristics. Dissolved solids in all the untreated waters analyzed ranged between 14 and 747 ppm (parts per million) but in those waters used in processing the dissolved solids content was less than 200 ppm. The cooling water used by the industry is also generally of very high quality, principally because the requirements for a high-quality process water necessitate location of the plants in areas where such water is available.

  10. Heatshield material selection for advanced ballistic reentry vehicles. [rayon fiber cloth impregnated with phenolic resin

    NASA Technical Reports Server (NTRS)

    Legendre, P. J.; Holtz, T.; Sikra, J. C.

    1980-01-01

    The Performance of staple rayon fiber and AVTEX continuous rayon fiber was evaluated as precursor materials for heatshields. The materials studied were referenced to the IRC FM5055A heatshield materials flown during the past decade. Three different arc jet facilities were used to simulate portions of the reentry environment. The IRC FM5055A and the AVTEX FM5055G, both continuous rayon fiber woven materials having the phenolic impregnant filled with carbon particles were compared. The AVTEX continuous fiber, unfilled material FM5822A was also examined to a limited extent. Test results show that the AVTEX FM5055G material provided a close substitute for the IRC FM5055A material both in terms of thermal protection and roll torque performance.

  11. Modified bamboo rayon-copper nanoparticle composites as antibacterial textiles.

    PubMed

    Teli, M D; Sheikh, Javed

    2013-10-01

    In the current study the bamboo rayon fabric grafted with acrylamide was utilized as a backbone to immobilize copper nanoprticles. The grafted bamboo rayon was first treated with CuSO4 followed by chemical reduction. The modified product was characterized using FTIR, TGA and SEM. The characteristic color developed after reduction was measured spectrophotometrically. The grafted bamboo rayon with Cu nanoparticles was then evaluated for antibacterial activity against both gram positive and gram negative bacteria and the durability of their antibacterial activity after washing. The product showed antibacterial activity against both types of bacterias which was found to be durable till 50 washes. The material can be claimed as suitable candidate for medical textile applications to prevent cross-infections. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Mutagenicity of commercial hair dyes and detection of 2,7-diaminophenazine.

    PubMed

    Watanabe, T; Hirayama, T; Fukui, S

    1990-08-01

    Four commercial oxidative-type hair dye formulations, A, B, C, and D, were treated with hydrogen peroxide (H2O2) to simulate normal conditions of use, and the oxidized hair dyes were tested for their mutagenicity in Salmonella typhimurium TA98 in the presence of a mammalian metabolic activation system (S9 mix). Most of them did not show obvious mutagenicity in the range of 1-25 microliters/plate and all exhibited bactericidal activity at 10 microliters/plate. In order to evaluate the mutagenicity of hair dyes both before and after H2O2 oxidation, rayon linked to a copper-phthalocyanine derivative (blue rayon) was used as an adsorbent for the elimination of interfering bactericidal compounds. Adsorbed compounds on blue rayon were eluted with ammoniacal methanol and eluents were subjected to the Ames test. The mutagenicity of the blue-rayon extracts in TA98 with S9 mix was increased by H2O2 oxidation. The blue-rayon extracts obtained from oxidized A and B were potent mutagens and reverted 334 and 999 colonies/10 microliters of original substance, respectively. In addition, 88 and 249 ng of 2,7-diaminophenazine, which was extremely mutagenic in TA98 with S9 mix, were detected in the extracts of 40 ml of the hair dye formulations A and B, respectively. The mutagenicity in oxidized hair dye formulations was successfully detected by use of blue-rayon extraction. 2,7-Diaminophenazine was only formed in the hair dye formulations containing m-phenylenediamine by H2O2 oxidation. Therefore, attention needs to be paid to the use of m-phenylenediamine as a hair dye component, not only for its own toxicity but also for that of its oxidation products.

  13. 40 CFR 414.20 - Applicability; description of the rayon fibers subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 30 2012-07-01 2012-07-01 false Applicability; description of the rayon fibers subcategory. 414.20 Section 414.20 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS...

  14. Effect of a depilatory agent on cotton, polyester, and rayon versus human hair in a laboratory setting.

    PubMed

    Plesa, Jocelyn A; Shoup, Kelly; Manole, Mioara D; Hickey, Robert W

    2015-03-01

    We examine the ability of a depilatory agent, Nair, to dissolve strands of hair, cotton, polyester, and rayon. We conducted a bench laboratory study in which we tested single strands of hair and natural and synthetic fibers under static tension with a 10.8-g weight and application of Nair. The dependent variable, time until breakage, was recorded. If the strand did not break within 8 hours, the experiment was discontinued. Three types of hair were tested (thin, medium, and thick, as recorded per diameter). Three types of natural and synthetic fibers were tested (cotton, polyester, and rayon). All types of hair had breakage within 10 minutes of the Nair application. Synthetic materials had no breakage after 8 hours with application of Nair. Depilatory agents dissolve hair under tension within minutes. However, they do not dissolve cotton, polyester, and rayon even after many hours of application. Copyright © 2014 American College of Emergency Physicians. Published by Elsevier Inc. All rights reserved.

  15. 76 FR 71831 - Defense Federal Acquisition Regulation Supplement: Fire-Resistant Fiber for Production of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-18

    ..., suppliers, or distributors of fire-resistant fibers, yarns, fabrics, or military uniforms) submitted.... The law does not restrict DoD's selection and use of fabrics containing fire-resistant rayon fiber... from selecting fabrics that include fire- resistant rayon fibers. Response: These responses have...

  16. Extraction of chitosan from shrimp shells waste and application in antibacterial finishing of bamboo rayon.

    PubMed

    Teli, M D; Sheikh, Javed

    2012-06-01

    Chitosan can be best utilized as safe antibacterial agent for textiles but there is always a limitation of its durability. The chitin containing shellfish waste is available in huge quantities, but very low quantities are utilized for extraction of high value products like chitosan. In the current work chitosan was extracted from shrimp shells and then used as antibacterial exhaust finishing agent for grafted bamboo rayon. Chitosan bound bamboo rayon was then evaluated for antibacterial activity against both gram positive and gram negative bacteria. The product showed antibacterial activity against both types of bacterias which was durable till 30 washes. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. Water, moisture and ash content of mechanically cleaned greige cotton, naturally colored brown cotton, flax and rayon

    USDA-ARS?s Scientific Manuscript database

    This exploratory research evaluated the Karl Fischer Titration reference method (KFT, ASTM D7785) to accurately measure water content of mechanically cleaned greige cotton, a naturally colored brown cotton, flax and rayon at moisture equilibrium. Each sample was analyzed by KFT, standard oven dryin...

  18. Cellulose Dressing Versus Rayon Dressing in Skin Graft Donor Sites: Aspects of Patients' Health-related Quality of Life and Self-esteem .

    PubMed

    Ferreira, Lydia M; Blanes, Leila; Gragnani, Alfredo; Veiga, Daniela F; Veiga, Frederico; Nery, Gilka B; Rocha, Gustavo H; Gomes, Heitor C; Rocha, Mario G; Okamoto, Regina

    2009-06-01

     Objective. The aim of this study was to compare the health-related quality of life (HRQoL) and self-esteem of patients who underwent split-thickness skin grafting, when either cellulose dressings or rayon dressings were applied to the donor sites. A total of 25 patients, who were enrolled at five participant hospitals and required split-thickness skin grafting for various clinical reasons, were randomized into two treatment groups, the rayon dressing group (n = 13), or the cellulose dressing group (n = 12). All patients were assessed preoperatively and 60 days postoperatively. The HRQoL was assessed with the Short Form-36 (SF-36) health survey questionnaire, and self-esteem was evaluated using the Rosenberg Self-Esteem Scale (RSE)/UNIFESP-EPM (Brazilian versions). There were no surgery-related complications during the study period. In both treatment groups, SF-36 scores for emotional role, mental health, vitality, and general health decreased from baseline. RSE scores increased from baseline in both treatment groups, showing a reduction in self-esteem after treatment. There was a statistical difference (P = 0.024) in the SF-36 bodily pain domain for the rayon group. There were no significant differences in HRQoL and self-esteem between treatment groups. In the rayon-dressing group, there was a significant decrease in bodily pain from baseline .

  19. 75 FR 6169 - Request for Public Comment on a Commercial Availability Request Under the U.S.-Singapore Free...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-08

    ... centimeters (52 inches). Finish: (Piece) dyed. Fabric 2 HTS Subheading: 6004.10.00. Fiber Content: 35% rayon...). Finish: (Piece) dyed. Fabric 3 HTS Subheading: 6001.22.00. Fiber Content: 79% rayon made from bamboo/15...: (Piece) dyed. (2) Certain knit fabrics of polyester fiber, of the specifications detailed below...

  20. Sustaining Phenolic Impregnated Carbon Ablator (PICA) TPS for Future NASA Robotic Science Missions Including NF-4 and Discovery

    NASA Technical Reports Server (NTRS)

    Venkatapathy, E.; Stackpoole, M.; Violette, S.

    2018-01-01

    Phenolic Impregnated Carbon Ablator (PICA), invented in the mid 1990s, is a low-density ablative thermal protection material proven capable of meeting sample return mission needs from the moon, asteroids, comets and other unrestricted class V destinations as well as for Mars. Its low density and efficient performance characteristics have proven effective for use from Discovery to Flagship class missions. It is important that NASA maintain this TPS material capability and ensure its availability for future NASA use. The rayon based carbon precursor raw material used in PICA preform manufacturing required replacement and requalification at least twice in the past 25 years and a third substitution is now needed. The carbon precursor replacement challenge is twofold the first involves finding a long-term replacement for the current rayon and the second is to assess its future availability periodically to ensure it is sustainable and be alerted if additional replacement efforts need to be initiated. Rayon is no longer a viable process in the US and Europe due to environmental concerns. In the early 80s rayon producers began investigating a new method of producing a cellulosic fiber through a more environmentally responsible process. This cellulosic fiber, lyocell, is a viable replacement precursor for PICA fiberform. This presentation reviews current SMD-PSD funded PICA sustainability activities in ensuring a rayon replacement for the long term is identified and in establishing that the capability of the new PICA derived from an alternative precursor is in family with previous versions of the so called heritage PICA.

  1. Sustaining PICA for Future NASA Robotic Science Missions Including NF-4 and Discovery

    NASA Technical Reports Server (NTRS)

    Stackpoole, Mairead; Venkatapathy, Ethiraj; Violette, Steven

    2018-01-01

    Phenolic Impregnated Carbon Ablator (PICA), invented in the mid 1990's, is a low-density ablative thermal protection material proven capable of meeting sample return mission needs from the moon, asteroids, comets and other "unrestricted class V destinations" as well as for Mars. Its low density and efficient performance characteristics have proven effective for use from Discovery to Flagship class missions. It is important that NASA maintain this TPS material capability and ensure its availability for future NASA use. The rayon based carbon precursor raw material used in PICA preform manufacturing required replacement and requalification at least twice in the past 25 years and a third substitution is now needed. The carbon precursor replacement challenge is twofold - the first involves finding a long-term replacement for the current rayon and the second is to assess its future availability periodically to ensure it is sustainable and be alerted if additional replacement efforts need to be initiated. Rayon is no longer a viable process in the US and Europe due to environmental concerns. In the early 80's rayon producers began investigating a new method of producing a cellulosic fiber through a more environmentally responsible process. This cellulosic fiber, lyocell, is a viable replacement precursor for PICA fiberform. This presentation reviews current SMD-PSD funded PICA sustainability activities in ensuring a rayon replacement for the long term is identified and in establishing that the capability of the new PICA derived from an alternative precursor is in family with previous versions of the so called "heritage" PICA.

  2. Process for the production of superconductor containing filaments

    DOEpatents

    Tuominen, Olli P.; Hoyt, Matthew B.; Mitchell, David F.; Morgan, Carol W.; Roberts, Clyde Gordon; Tyler, Robert A.

    2002-01-01

    Superconductor containing filaments having embedments of superconducting material surrounded by a rayon matrix are formed by preparing a liquid suspension which contains at least 10 weight percent superconducting material; forming a multicomponent filament having a core of the suspension and a viscose sheath which contains cellulose xanthate; and thereafter, regenerating cellulose from the cellulose xanthate to form a rayon matrix.

  3. JPRS Report, Soviet Union, Political Affairs

    DTIC Science & Technology

    1989-08-16

    of many farms, party, soviet, and agricultural agencies in several rayons have lessened attention to the intensive development of animal husbandry...increasing, and proper attention is not being paid to working and living conditions for animal breeders. In Moskovskiy Rayon in 1988, a reduction in meat...offer services to the population, and prepare and reprocess secondary resources. The party committee should pay greater attention to the formation

  4. From air to clothing: characterizing the accumulation of semi-volatile organic compounds to fabrics in indoor environments.

    PubMed

    Saini, A; Okeme, J O; Mark Parnis, J; McQueen, R H; Diamond, M L

    2017-05-01

    Uptake kinetics of semi-volatile organic compounds (SVOCs) present indoors, namely phthalates and halogenated flame retardants (HFRs), were characterized for cellulose-based cotton and rayon fabrics. Cotton and rayon showed similar accumulation of gas- and particle-phase SVOCs, when normalized to planar surface area. Accumulation was 3-10 times greater by rayon than cotton, when normalized to Brunauer-Emmett-Teller (BET) specific surface area which suggests that cotton could have a longer linear uptake phase than rayon. Linear uptake rates of eight consistently detected HFRs over 56 days of 0.35-0.92 m 3 /day.dm 2 planar surface area and mass transfer coefficients of 1.5-3.8 m/h were statistically similar for cotton and rayon and similar to those for uptake to passive air sampling media. These results suggest air-side controlled uptake and that, on average, 2 m 2 of clothing typically worn by a person would sequester the equivalent of the chemical content in 100 m 3 of air per day. Distribution coefficients between fabric and air (K') ranged from 6.5 to 7.7 (log K') and were within the range of partition coefficients measured for selected phthalates as reported in the literature. The distribution coefficients were similar for low molecular weight HFRs, and up to two orders of magnitude lower than the equilibrium partition coefficients estimated using the COSMO-RS model. Based on the COSMO-RS model, time to reach 95% of equilibrium for PBDEs between fabric and gas-phase compounds ranged from 0.1 to >10 years for low to high molecular weight HFRs. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  5. Spectral Textile Detection in the VNIR/SWIR Band

    DTIC Science & Technology

    2015-03-01

    swath (a red cotton shirt). The spectrum collected using a contact probe is shown in blue (solid line), while the spectrum collected with a remote...contact probe and the Fieldspec® 3 spectroradiometer. Curves corresponding to textiles ( cotton , polyester, nylon, acrylic, and wool) are shown in blue...can be used to detect dismounts. Composition. Commonly used plant fibers are cotton , rayon, flax, and hemp. Cotton and rayon are composed of cellulose

  6. Diffraction de rayons X sur les plaquettes de fer durcies par cyanuration

    NASA Astrophysics Data System (ADS)

    Popescu, M.; Hoyer, W.; Stegarescu, M.; Cornet, A.; Broll, N.

    2004-11-01

    Une méthode de cyanuration a été developpée pour les surfaces des plaquettes de fer, basée sur une réaction thermochimique qui conduit à la formation des couches dures sur le métal. Les échantillons ont été analysés, pour de temps différents de traitement, par diffraction de rayons X et par mesures de dureté.

  7. Selecting the best rayon in customer’s perspective using fuzzy analytic hierarchy process

    NASA Astrophysics Data System (ADS)

    Sonjaya, E. G.; Paulus, E.; Hidayat, A.

    2018-03-01

    Annually, the best Rayon selection is conducted by the assessment team of PT.PLN (Persero) Cirebon with the goal to increase the spirit of company members in providing an improved service for customers. However, there is a problem in multiple criteria decision making in this case, which is the importance intensity of each criterion in the selection are often assessed subjectively. To solve this problem, Fuzzy Analytical Hierarchy Process are used to cover AHP scale deficiency in the form of ‘crisp’ numbers. So, it should be considered to use Fuzzy logic approach to handle uncertainty. Fuzzy approach, especially triangular fuzzy number towards AHP scale, are expected to minimize the handling of subjective input, which then will make a more objective result. Thus, this research was conducted to help the management or assessment team in the selection of the best Rayon with a more objective selection in according to the company criteria.

  8. Quantitative assessment of vaginal microflora during use of tampons of various compositions.

    PubMed Central

    Onderdonk, A B; Zamarchi, G R; Rodriguez, M L; Hirsch, M L; Muñoz, A; Kass, E H

    1987-01-01

    Although the effect of vaginal tampons on the microbial flora during menstruation has recently been studied by several investigators, quantitative effects attributable to particular tampon fibers have received less attention. The purposes of the present study were (i) to determine and then to compare the effects of polyacrylate rayon tampons and viscose rayon tampons on the normal vaginal flora, (ii) to compare quantitative bacterial counts obtained from these tampons with those obtained from concomitant vaginal swabs, and (iii) to determine whether either of these tampon types alters the vaginal microflora when compared with the microflora in the same women using all-cotton tampons or external catamenial pads. Tampon and swab samples were obtained at predetermined times from 18 women for an average of seven menstrual cycles. Samples consisting of swabs from women wearing menstrual pads were compared with swab and tampon samples taken at predetermined times during the menstrual cycle from women using cotton, polyacrylate rayon, or viscose rayon tampons. Samples were analyzed for total aerobic, facultative, and anaerobic bacterial counts. Statistical evaluation of the results indicated that, on the whole, total bacterial counts decreased during menstruation and that the numbers of bacteria in tampons tended to be lower than those in swab samples taken at the same time. The tampon type had little effect on the vaginal microflora. PMID:3435142

  9. Ethnobotany in Rayones, Nuevo León, México.

    PubMed

    Estrada-Castillón, Eduardo; Garza-López, Miriam; Villarreal-Quintanilla, José Ángel; Salinas-Rodríguez, María Magdalena; Soto-Mata, Brianda Elizabeth; González-Rodríguez, Humberto; González-Uribe, Dino Ulises; Cantú-Silva, Israel; Carrillo-Parra, Artemio; Cantú-Ayala, César

    2014-09-01

    Trough collections of plants and interviews with 110 individuals, an ethnobotanical study was conducted in order to determine the knowledge and use plant species in Rayones, Nuevo Leon, Mexico. The aim of this study was to record all useful plants and their uses, to know whether differences exist in the knowledge about the number of species and uses between women and men, and to know if there is a correlation between the age of individuals and knowledge of species and their uses. A total of 110 persons were interviewed (56 men, 56 women). Semistructured interviews were carried out. The data were analyzed by means of Student t test and the Pearson Correlation Coeficient. A total of 252 species, 228 genera and 91 families of vascular plants were recorded. Astraceae, Fabaceae and are the most important families with useful species and Agave and Opuntia are the genera with the highest number of useful species. One hundred and thirty six species are considered as medicinal. Agave, Acacia and Citrus are the genera with the highest number of medicinal species. Other uses includes edible, spiritual rituals, construction and ornamentals. There was a non-significant correlation between the person's age and number of species, but a significant very low negative correlation between the person's age and number of uses was found. Knowing their medicinal uses is an important issue for the people of Rayones. Boiling and preparing infusions are the main ways of using plants by residents. The leaves, the branches, and the fruits are the most commonly used parts. Almost 18% of the flora is used for wood and construction purposes. Several uses such as cosmetic, shampoo, firming skin tonics and health hair products recorded in Rayones has not been reported for other areas in the state of Nuevo León. In Rayones, women have a greater knowledge about plants and their uses than men, particularly, medicinal plants, but, men have a greater knowledge about wood and construction species.

  10. Evaluation of a Wipe Surface Sample Method for Collection of Bacillus Spores from Nonporous Surfaces▿

    PubMed Central

    Brown, Gary S.; Betty, Rita G.; Brockmann, John E.; Lucero, Daniel A.; Souza, Caroline A.; Walsh, Kathryn S.; Boucher, Raymond M.; Tezak, Mathew; Wilson, Mollye C.; Rudolph, Todd

    2007-01-01

    Polyester-rayon blend wipes were evaluated for efficiency of extraction and recovery of powdered Bacillus atrophaeus spores from stainless steel and painted wallboard surfaces. Method limits of detection were also estimated for both surfaces. The observed mean efficiency of polyester-rayon blend wipe recovery from stainless steel was 0.35 with a standard deviation of ±0.12, and for painted wallboard it was 0.29 with a standard deviation of ±0.15. Evaluation of a sonication extraction method for the polyester-rayon blend wipes produced a mean extraction efficiency of 0.93 with a standard deviation of ±0.09. Wipe recovery quantitative limits of detection were estimated at 90 CFU per unit of stainless steel sample area and 105 CFU per unit of painted wallboard sample area. The method recovery efficiency and limits of detection established in this work provide useful guidance for the planning of incident response environmental sampling following the release of a biological agent such as Bacillus anthracis. PMID:17122390

  11. Evaluation of a wipe surface sample method for collection of Bacillus spores from nonporous surfaces.

    PubMed

    Brown, Gary S; Betty, Rita G; Brockmann, John E; Lucero, Daniel A; Souza, Caroline A; Walsh, Kathryn S; Boucher, Raymond M; Tezak, Mathew; Wilson, Mollye C; Rudolph, Todd

    2007-02-01

    Polyester-rayon blend wipes were evaluated for efficiency of extraction and recovery of powdered Bacillus atrophaeus spores from stainless steel and painted wallboard surfaces. Method limits of detection were also estimated for both surfaces. The observed mean efficiency of polyester-rayon blend wipe recovery from stainless steel was 0.35 with a standard deviation of +/-0.12, and for painted wallboard it was 0.29 with a standard deviation of +/-0.15. Evaluation of a sonication extraction method for the polyester-rayon blend wipes produced a mean extraction efficiency of 0.93 with a standard deviation of +/-0.09. Wipe recovery quantitative limits of detection were estimated at 90 CFU per unit of stainless steel sample area and 105 CFU per unit of painted wallboard sample area. The method recovery efficiency and limits of detection established in this work provide useful guidance for the planning of incident response environmental sampling following the release of a biological agent such as Bacillus anthracis.

  12. Characterization and Oxidation Behavior of Rayon-Derived Carbon Fibers

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan; Hull, David

    2010-01-01

    Rayon-derived fibers are the central constituent of reinforced carbon/ carbon (RCC) composites. Optical, scanning electron, and transmission electron microscopy were used to characterize the as-fabricated fibers and the fibers after oxidation. Oxidation rates were measured with weight loss techniques in air and oxygen. The as-received fibers are approximately 10 micron in diameter and characterized by grooves or crenulations around the edges. Below 800 C, in the reaction-controlled region, preferential attack began in the crenulations and appeared to occur down fissures in the fibers.

  13. Ethnobotany in Rayones, Nuevo León, México

    PubMed Central

    2014-01-01

    Background Trough collections of plants and interviews with 110 individuals, an ethnobotanical study was conducted in order to determine the knowledge and use plant species in Rayones, Nuevo Leon, Mexico. The aim of this study was to record all useful plants and their uses, to know whether differences exist in the knowledge about the number of species and uses between women and men, and to know if there is a correlation between the age of individuals and knowledge of species and their uses. Methods A total of 110 persons were interviewed (56 men, 56 women). Semistructured interviews were carried out. The data were analyzed by means of Student t test and the Pearson Correlation Coeficient. Results A total of 252 species, 228 genera and 91 families of vascular plants were recorded. Astraceae, Fabaceae and are the most important families with useful species and Agave and Opuntia are the genera with the highest number of useful species. One hundred and thirty six species are considered as medicinal. Agave, Acacia and Citrus are the genera with the highest number of medicinal species. Other uses includes edible, spiritual rituals, construction and ornamentals. There was a non-significant correlation between the person’s age and number of species, but a significant very low negative correlation between the person’s age and number of uses was found. Conclusions Knowing their medicinal uses is an important issue for the people of Rayones. Boiling and preparing infusions are the main ways of using plants by residents. The leaves, the branches, and the fruits are the most commonly used parts. Almost 18% of the flora is used for wood and construction purposes. Several uses such as cosmetic, shampoo, firming skin tonics and health hair products recorded in Rayones has not been reported for other areas in the state of Nuevo León. In Rayones, women have a greater knowledge about plants and their uses than men, particularly, medicinal plants, but, men have a greater knowledge about wood and construction species. PMID:25179469

  14. "No fertile soil for pathogens": rayon, advertising, and biopolitics in late Weimar Germany.

    PubMed

    Lane, Yvette Florio

    2010-01-01

    Recent research on twentieth-century German history has begun to re-examine the centrality of race as a category of analysis. While not discounting its importance in the shaping and enacting of Nazi policies and practices, race is seen instead as one among many factors leading to the crimes of the Nazi regime. In this paper, the author considers the role consumerist desires and fantasies played in the wider context of the inter-war European fascination with notions of technology, "hygiene," democracy, and modernity. Using advertisements that were created to promote manufactured-fiber (rayon) apparel, this article suggests that continuities across cultures and time periods necessitate a re-evaluation of race as the signal organizing principal. Instead, the author argues that by complicating the intersections between class, science and technology, and an emerging, but troubling, modernity, 1920s rayon advertising offers an especially rich site for analysis of the ways in which biopolitics and nascent consumerism both sold products and constructed ideologies before 1933, and influenced the post-war welfare state.

  15. Progress in Manufacturing and Characterizing Domestic Lyocell PICA (PICA-D) and Comparison to Heritage PICA

    NASA Technical Reports Server (NTRS)

    Venkatapathy, Ethiraj; Stackpoole, Mairead; Gasch, Matthew; Violette, Steve

    2018-01-01

    NASA ARC is working with SMD-PSD to address PICA rayon sustainability concerns. In FY16/17, Lyocell Based PICA (PICA-D) was manufactured and limited testing performed showing it to be a good candidate as a potential replacement for heritage rayon. Establishing PICA-D as a "drop in replacement" will allow missions to depend on and design missions with PICA without any risk typical of a replacement. Establishing the extended capability of PICA-D will allow Sample Return Missions with higher entry speed that were not considered before.

  16. A comparative study on the graft copolymerization of acrylic acid onto rayon fibre by a ceric ion redox system and a γ-radiation method.

    PubMed

    Kaur, Inderjeet; Kumar, Raj; Sharma, Neelam

    2010-10-13

    Functionalization of rayon fibre has been carried out by grafting acrylic acid (AAC) both by a chemical method using a Ce(4+)-HNO(3) redox initiator and by a mutual irradiation (γ-rays) method. The reaction conditions affecting the grafting percentage have been optimized for both methods, and the results are compared. The maximum percentage of grafting (50%) by the chemical method was obtained utilizing 18.24 × 10(-3) moles/L of ceric ammonium nitrate (CAN), 39.68 × 10(-2) moles/L of HNO(3), and 104.08 × 10(-2) moles/L of AAc in 20 mL of water at 45°C for 120 min. For the radiation method, the maximum grafting percentage (60%) was higher, and the product was obtained under milder reaction conditions using a lower concentration of AAc (69.38 × 10(-2) moles/L) in 10 mL of water at an optimum total dose of 0.932 kGy. Swelling studies showed higher swelling for the grafted rayon fibre in water (854.54%) as compared to the pristine fibre (407%), while dye uptake studies revealed poor uptake of the dye (crystal violet) by the grafted fibre in comparison with the pristine fibre. The graft copolymers were characterized by IR, TGA, and scanning electron micrographic methods. Grafted fibre, prepared by the radiation-induced method, showed better thermal behaviour. Comparison of the two methods revealed that the radiation method of grafting of acrylic acid onto rayon fibre is a better method of grafting in comparison with the chemical method. Copyright © 2010 Elsevier Ltd. All rights reserved.

  17. Sustaining PICA for Future NASA Robotic Science Missions Including NF-4 and Discovery

    NASA Technical Reports Server (NTRS)

    Stackpoole, Mairead; Venkatapathy, Ethiraj; Violette, Steve

    2018-01-01

    Phenolic Impregnated Carbon Ablator (PICA), invented in the mid 1990's, is a low-density ablative thermal protection material proven capable of meeting sample return mission needs from the moon, asteroids, comets and other unrestricted class V destinations as well as for Mars. Its low density and efficient performance characteristics have proven effective for use from Discovery to Flag-ship class missions. It is important that NASA maintain this thermal protection material capability and ensure its availability for future NASA use. The rayon based carbon precursor raw material used in PICA preform manufacturing has experienced multiple supply chain issues and required replacement and requalification at least twice in the past 25 years and a third substitution is now needed. The carbon precursor replacement challenge is twofold - the first involves finding a long-term replacement for the current rayon and the second is to assess its future availability periodically to ensure it is sustainable and be alerted if additional replacement efforts need to be initiated. This paper reviews current PICA sustainability activities to identify a rayon replacement and to establish that the capability of the new PICA derived from an alternative precursor is in family with previous versions.

  18. Ignition characteristics of some aircraft interior fabrics

    NASA Technical Reports Server (NTRS)

    Hilado, C. J.; Brandt, D. L.

    1978-01-01

    Six samples of aircraft interior fabrics were evaluated with regard to resistance to ignition by radiant heat. Five samples were aircraft seat upholstery fabrics and one sample was an aircraft curtain fabric. The aircraft seat fabrics were 100% wool (2 samples), 83% wool/17% nylon, 49% wool/51% polyvinyl chloride, and 100% rayon. The aircraft curtain fabric was 92% modacrylic/8% polyester. The five samples of aircraft seat upholstery fabrics were also evaluated with regard to resistance to ignition by a smoldering cigarette. The four samples of wool-containing aircraft seat fabrics appeared to be superior to the sample of rayon seat fabric in resistance to ignition, both by radiant heat and by a smoldering cigarette.

  19. Effect of oxygen plasma treatment on the electrochemical performance of the rayon and polyacrylonitrile based carbon felt for the vanadium redox flow battery application

    NASA Astrophysics Data System (ADS)

    Dixon, D.; Babu, D. J.; Langner, J.; Bruns, M.; Pfaffmann, L.; Bhaskar, A.; Schneider, J. J.; Scheiba, F.; Ehrenberg, H.

    2016-11-01

    Oxygen plasma treatment was applied on commercially available graphite felt electrodes based on rayon (GFA) and polyacrylonitrile (GFD). The formation of functional groups on the surface of the felt was confirmed by X-ray photoelectron spectroscopy measurements. The BET studies of the plasma treated electrodes showed no significant increase in surface area for both the rayon as well as the PAN based felts. Both plasma treated electrodes showed significantly enhanced V3+/V2+ redox activity compared to the pristine electrodes. Since an increase of the surface area has been ruled out for plasma treated electrode the enhanced activity could be attributed to surface functional groups. Interestingly, plasma treated GFD felts showed less electrochemical activity towards V5+/V4+ compared to the pristine electrode. Nevertheless, an overall increase of the single cell performance was still observed as the negative electrode is known to be the performance limiting electrode. Thus, to a great extent the present work helps to preferentially understand the importance of functional groups on the electrochemical activity of negative and positive redox reaction. The study emphasizes the need of highly active electrodes especially at the negative electrode side as inactive electrodes can still facilitate hydrogen evolution and degrade the electrolyte in VRFBs.

  20. Structure and properties of novel fibers spun from cellulose in NaOH/thiourea aqueous solution.

    PubMed

    Ruan, Dong; Zhang, Lina; Zhou, Jinping; Jin, Huiming; Chen, Hui

    2004-12-15

    Cellulose was dissolved rapidly in a NaOH/thiourea aqueous solution (9.5:4.5 in wt.-%) to prepare a transparent cellulose solution, which was employed, for the first time, to spin a new class of regenerated cellulose fibers by wet spinning. The structure and mechanical properties of the resulting cellulose fibers were characterized, and compared with those of commercially available viscose rayon, cuprammonium rayon and Lyocell fibers. The results from wide angle X-ray diffraction and CP/MAS 13C NMR indicated that the novel cellulose fibers have a structure typical for a family II cellulose and possessed relatively high degrees of crystallinity. Scanning electron microscopy (SEM) and optical microscopy images revealed that the cross-section of the fibers is circular, similar to natural silk. The new fibers have higher molecular weights and better mechanical properties than those of viscose rayon. This low-cost technology is simple, different from the polluting viscose process. The dissolution and regeneration of the cellulose in the NaOH/thiourea aqueous solutions were a physical process and a sol-gel transition rather than a chemical reaction, leading to the smoothness and luster of the fibers. This work provides a potential application in the field of functional fiber manufacturing.

  1. Proceedings of the 7th Semiannual Meeting of the Nozzle Initiative Industry Advisory Committee on Standardization of Carbon-Phenolic Test Methods and Specifications

    NASA Technical Reports Server (NTRS)

    Hall, William B. (Compiler); Pinoli, Pat C. (Compiler); Upton, Cindy G. (Compiler)

    1991-01-01

    The application of carbon fibers and fabrics (CF) for producing rocket nozzles is discussed. These materials which are essential for fabricating the carbon composites used in aerospace systems gasify when exposed to high temperatures and the mechanical properties of the composites degrade. The oxidation kinetics under isothermal (IC) and non-isothermal (NIC) conditions are examined and a comparison is made between the characteristics of IC and NIC oxidation. Several CF, chars, and carbon blacks were examined, including a microporous char, a graphitized rayon fabric, and several carbonized rayon fabrics. A summary is given of the advantages and drawbacks of isothermal and non-isothermal oxidation of carbons. The proceedings are assembled in the form of a roundtable discussion.

  2. 40 CFR 414.30 - Applicability; description of the other fibers subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Other Fibers... SIC 2823 cellulosic man-made fibers, except Rayon, and SIC 2824 synthetic organic fibers including...

  3. 40 CFR 414.30 - Applicability; description of the other fibers subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Other Fibers... SIC 2823 cellulosic man-made fibers, except Rayon, and SIC 2824 synthetic organic fibers including...

  4. 40 CFR 414.30 - Applicability; description of the other fibers subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Other Fibers... SIC 2823 cellulosic man-made fibers, except Rayon, and SIC 2824 synthetic organic fibers including...

  5. 40 CFR 414.30 - Applicability; description of the other fibers subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Other Fibers... SIC 2823 cellulosic man-made fibers, except Rayon, and SIC 2824 synthetic organic fibers including...

  6. 40 CFR 414.30 - Applicability; description of the other fibers subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS... classified under SIC 2823 cellulosic man-made fibers, except Rayon, and SIC 2824 synthetic organic fibers...

  7. Variation in Phenometric Lapse Rates in Pasture Resources across Four Rayons in Kyrgyzstan

    NASA Astrophysics Data System (ADS)

    Henebry, G. M.; Tomaszewska, M. A.; Kelgenbaeva, K.

    2017-12-01

    High elevation pasture resources form the foundation of agro-pastoralist livelihoods in Kyrgyzstan and elsewhere in montane Central Asia. We explore the temporal and the topographical variation in phenometric lapse rates (PLRs: the change in a phenometric as a function of elevation) across four rayons in two oblasts of the Kyrgyz Republic—Alay, At-Bashy, Chong Alay, and Naryn—with the aim of identifying and quantifying robust generic patterns in the PLRs. We evaluate two fundamental phenometrics derived from the downward convex quadratic model of land surface phenology that links the NDVI to accumulated growing degree-day (AGDD). The peak height (PH) is the maximum NDVI value obtained from the fitted model. The thermal time to peak (TTP) is the amount of AGDD required to reach the PH. We fitted sixteen years of Landsat NDVI data at 30 m spatial resolution to annual AGDD progressions derived from MODIS land surface temperature time series at 1 km spatial resolution, yielding maps for each phenometric. If the coefficient of determination was less than 0.5, then the model fit was deemed a failure. We classified the reliability of pasture resources into five classes based on the number of years of successful model fit: very persistent (14-16 y); persistent (11-13 y); marginal (7-10 y); occasional (4-6); and rare (1-3). We explore the interactive roles of elevation, slope, aspect, latitude, and rayon on the PLRs and pasture resource persistence to identify critical areas for resource management.

  8. 40 CFR Table 1 to Subpart Uuuu of... - Emission Limits and Work Practice Standards

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... cellulosic sponge operation i. reduce total uncontrolled sulfide emissions (reported as carbon disulfide) by... process unit” mean “cellulose food casing, rayon, cellulosic sponge, cellophane, or cellulose ether...

  9. Microbial and immunological investigations and remedial action after an outbreak of humidifier fever

    PubMed Central

    Edwards, J H

    1980-01-01

    ABSTRACT Humidifier fever (Monday sickness) occuring in office staff in a factory processing rayon presented as pyrexia with a polyuria and leucocytosis on the first day back to work after a break during the winter half of the year. Chest radiographs showed no abnormalities but pulmonary function tests indicated mild airways obstruction in the affected group as a whole. Respirable dust samples taken on a Monday when 11 cases occured were not pyrogenic, indicating that a mechanism other than direct pyrogen activity produced the pyrexia. Efforts were then directed to determining an immunological basis for the episodes. In particular, Thermoactinomyces vulgaris, previously held responsible for humidifier fever, was studied. During the episode of 11 cases, the number of viable airborne spores of this organism was far higher than on Mondays when no cases occured. In a second episode of nine cases, however, the airborne viable count was of the same order as non-episode Mondays. Extracts of T vulgaris produced lines of precipitation in gel diffusion studies with roughly half the office staff sera tested, but no correlation was observed between precipitin line formation and disease. A similar proportion of normal sera reacted against this extract. Extracts of dust lying on the topside surface of the suspended ceiling above the office, however, produced precipitin lines with sera from 16/18 affected individuals and 2/18 non-affected individuals (p < 0·001) as did extracts of humidifier material. Extensive microbial analysis failed to detect any one fungus or bacterium that produced antigens capable of reacting with positive serum, but extracts of amoebae correlated absolutely with humidifier material and ceiling dust extract in gel diffusion studies. A reaction of identity observed between the amoebae and ceiling dust extracts showed the presence of identical antigens. In similar studies the high degree of cross reactivity with antigens and sera from Spanish and Swedish outbreaks was obtained, which suggested a common antigen source in humidifier fever. That these antigens were produced by microbial development on rayon fibre could be shown by incubating rayon dust from the factory atmosphere with sterile water and testing with sera from affected individuals. Bales of rayon entering the factory did not have this potential to develop antigens, indicating microbial contamination after handling and processing. The initial source of contamination was considered to be the humidifier disseminating microbial spores and cysts throughout the factory and on to the suspended ceiling above the office. These were capable of secondary development on settled rayon fly under wet conditions, and evidence for this was obtained. Remedial action included cleaning the humidifier, modifying the baffle plates, running water to waste, and installing a prefilter. Dust was eliminated from the office area, and new accommodation, including the building of an office block detached from the main factory, was arranged for the office workers. So far no further cases have been reported. Images PMID:6768379

  10. Ozone decomposing filter

    DOEpatents

    Simandl, Ronald F.; Brown, John D.; Whinnery, Jr., LeRoy L.

    1999-01-01

    In an improved ozone decomposing air filter carbon fibers are held together with a carbonized binder in a perforated structure. The structure is made by combining rayon fibers with gelatin, forming the mixture in a mold, freeze-drying, and vacuum baking.

  11. Fact Sheet: Proposed Hazardous Air Pollutant Regulation for the Miscellaneous Cellulose Products Manufacturing

    EPA Pesticide Factsheets

    This August 2000 document contains information regarding the National Emissions Standards for Hazardous Air Pollutants for Cellulose Products Manufacturing. Some of the products of this industry are: cellulose, cellophane, and rayon.

  12. 40 CFR 414.21 - Effluent limitations representing the degree of effluent reduction attainable by the application...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Rayon Fibers... concentration listed in the following table. Effluent characteristics BPT effluent limitations 1 Maximum for any...

  13. 16 CFR 300.18 - Use of name of specialty fiber.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... designation permitted under this rule: 55% Alpaca—45% Camel Hair 50% Recycled Camel Hair—50% Wool 60% Recycled Alpaca—40% Rayon 35% Recycled Llama—35% Recycled Vicuna—30% Cotton 60% Cotton—40% Recycled Llama. (b...

  14. 16 CFR 300.18 - Use of name of specialty fiber.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... designation permitted under this rule: 55% Alpaca—45% Camel Hair 50% Recycled Camel Hair—50% Wool 60% Recycled Alpaca—40% Rayon 35% Recycled Llama—35% Recycled Vicuna—30% Cotton 60% Cotton—40% Recycled Llama. (b...

  15. 16 CFR 300.18 - Use of name of specialty fiber.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... designation permitted under this rule: 55% Alpaca—45% Camel Hair 50% Recycled Camel Hair—50% Wool 60% Recycled Alpaca—40% Rayon 35% Recycled Llama—35% Recycled Vicuna—30% Cotton 60% Cotton—40% Recycled Llama. (b...

  16. 16 CFR 300.18 - Use of name of specialty fiber.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... designation permitted under this rule: 55% Alpaca—45% Camel Hair 50% Recycled Camel Hair—50% Wool 60% Recycled Alpaca—40% Rayon 35% Recycled Llama—35% Recycled Vicuna—30% Cotton 60% Cotton—40% Recycled Llama. (b...

  17. Miroirs multicouches C/SI a incidence normale pour la region spectrale 25-40 nanometres

    NASA Astrophysics Data System (ADS)

    Grigonis, Marius

    Nous avons propose la nouvelle combinaison de materiaux, C/Si, pour la fabrication de miroirs multicouches a incidence normale dans la region spectrale 25-40 nm. Les resultats experimentaux montrent que cette combinaison possede une reflectivite d'environ ~25% dans la region spectrale 25-33 nm et une reflectivite d'environ ~23% dans la region spectrale 33-40 nm. Ces valeurs de reflectivite sont les plus grandes obtenues jusqu'a maintenant dans la region spectrale 25-40 nm. Les miroirs multicouches ont ete par la suite caracterises par microscopie electronique a transmission, par diverses techniques de diffraction des rayons X et par spectroscopies d'electrons AES et ESCA. La resistance des miroirs aux temperatures elevees a ete egalement etudiee. Les resultats fournis par les methodes de caracterisation indiquent que cette combinaison possede des caracteristiques tres prometteuses pour son application comme miroir pour les rayons X mous.

  18. Absorbent properties of carboxymethylated fiber, hydroentangled nonwoven and regenerated cellulose: a comparative study

    USDA-ARS?s Scientific Manuscript database

    Commercially-available, bleached cotton fibers, rayon, and their hydroentangled counterparts were carboxymethylated to produce cellulosic products with increased absorbency. These cellulose materials were tested for absorbance, spectroscopic properties, degree of substitution and carding ability. Ca...

  19. 16 CFR 303.11 - Floor coverings containing backings, fillings, and paddings.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... disclosure shall be made in such manner as to indicate that it relates only to the face, pile, or outer... these types of floor coverings as to fiber content are as follows: 100% Cotton Pile Face—60% Rayon, 40...

  20. 40 CFR 63.5485 - Am I subject to this subpart?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... manufacturing includes both the Miscellaneous Viscose Processes source category and the Cellulose Ethers Production source category. The Miscellaneous Viscose Processes source category includes all of the operations that use the viscose process. These operations include the cellulose food casing, rayon...

  1. 16 CFR 303.11 - Floor coverings containing backings, fillings, and paddings.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... disclosure shall be made in such manner as to indicate that it relates only to the face, pile, or outer... these types of floor coverings as to fiber content are as follows: 100% Cotton Pile Face—60% Rayon, 40...

  2. 16 CFR 303.11 - Floor coverings containing backings, fillings, and paddings.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... disclosure shall be made in such manner as to indicate that it relates only to the face, pile, or outer... these types of floor coverings as to fiber content are as follows: 100% Cotton Pile Face—60% Rayon, 40...

  3. 16 CFR 303.11 - Floor coverings containing backings, fillings, and paddings.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... disclosure shall be made in such manner as to indicate that it relates only to the face, pile, or outer... these types of floor coverings as to fiber content are as follows: 100% Cotton Pile Face—60% Rayon, 40...

  4. 16 CFR 303.11 - Floor coverings containing backings, fillings, and paddings.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... disclosure shall be made in such manner as to indicate that it relates only to the face, pile, or outer... these types of floor coverings as to fiber content are as follows: 100% Cotton Pile Face—60% Rayon, 40...

  5. Potential development of a new cotton-based antimicrobial wipe

    USDA-ARS?s Scientific Manuscript database

    The adsorption of a cationic biocide on various cotton and synthetic nonwoven fabrics was investigated using UV-Vis absorption spectroscopy. The results reveal that rayon and greige cotton nonwovens adsorb nearly three times more cationic biocide than comparable bleached cotton substrates. Polyester...

  6. Microscopie par rayons X dans la fenêtre de l'eau : faisabilité et intérêt pour la biologie d'un instrument de laboratoire

    NASA Astrophysics Data System (ADS)

    Adam, J. F.; Moy, J. P.

    2005-06-01

    La biologie étudie des structures ou des phénomènes sub-cellulaires. Pour cela la microscopie est la technique d'observation privilégiée. La résolution spatiale de la microscopie optique s'avère bien souvent insuffisante pour de telles observations. Les techniques plus résolvantes, comme la microscopie électronique par transmission sont souvent destructrices et d'une complexité peu adaptée aux besoins des biologistes. La microscopie par rayons X dans la fenêtre de l'eau permet l'imagerie rapide de cellules dans leur milieu naturel, nécessite peu de préparation et offre des résolutions de quelques dizaines de nanomètres. De plus, il existe un bon contraste naturel entre les structures carbonées (protéines, lipides) et l'eau. Actuellement cette technique est limitée aux centres de rayonnement synchrotron, ce qui impose une planification et des déplacements incompatibles avec les besoins de la biologie. Un tel microscope fonctionnant avec uns source de laboratoire serait d'une grande utilité. Ce document présente un état de l'art de la microscopie par rayons X dans la fenêtre de l'eau. Un cahier des charges détaillé pour un appareil de laboratoire ayant les performances optiques requises par les biologistes est présenté et confronté aux microscopes X de laboratoire déjà existants. Des solutions concernant la source et les optiques sont également discutées.

  7. Evaluation of rayon swab surface sample collection method for Bacillus spores from nonporous surfaces.

    PubMed

    Brown, G S; Betty, R G; Brockmann, J E; Lucero, D A; Souza, C A; Walsh, K S; Boucher, R M; Tezak, M S; Wilson, M C; Rudolph, T; Lindquist, H D A; Martinez, K F

    2007-10-01

    To evaluate US Centers for Disease Control and Prevention recommended swab surface sample collection method for recovery efficiency and limit of detection for powdered Bacillus spores from nonporous surfaces. Stainless steel and painted wallboard surface coupons were seeded with dry aerosolized Bacillus atrophaeus spores and surface concentrations determined. The observed mean rayon swab recovery efficiency from stainless steel was 0.41 with a standard deviation (SD) of +/-0.17 and for painted wallboard was 0.41 with an SD of +/-0.23. Evaluation of a sonication extraction method for the rayon swabs produced a mean extraction efficiency of 0.76 with an SD of +/-0.12. Swab recovery quantitative limits of detection were estimated at 25 colony forming units (CFU) per sample area for both stainless steel and painted wallboard. The swab sample collection method may be appropriate for small area sampling (10 -25 cm2) with a high agent concentration, but has limited value for large surface areas with a low agent concentration. The results of this study provide information necessary for the interpretation of swab environmental sample collection data, that is, positive swab samples are indicative of high surface concentrations and may imply a potential for exposure, whereas negative swab samples do not assure that organisms are absent from the surfaces sampled and may not assure the absence of the potential for exposure. It is critical from a public health perspective that the information obtained is accurate and reproducible. The consequence of an inappropriate public health response founded on information gathered using an ineffective or unreliable sample collection method has the potential for undesired social and economic impact.

  8. 40 CFR 63.5485 - Am I subject to this subpart?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE CATEGORIES National Emission Standards for Hazardous Air Pollutants for Cellulose Products Manufacturing What This Subpart Covers § 63... operations that use the viscose process. These operations include the cellulose food casing, rayon...

  9. MUTAGENIC CHARACTERISTICS OF RIVER WATERS FLOWING THROUGH LARGE METROPOLITAN AREAS IN NORTH AMERICA

    EPA Science Inventory

    Mutagenic characteristics of river waters flowing through large metropolitan areas in North America

    The hanging technique using blue rayon, which specifically adsorbs mutagens with multicyclic planar structures, has the advantages over most conventional methods of not havi...

  10. MUTAGENIC PROPERTIES OF RIVER WATERS FLOWING THROUGH BIG CITY AREAS IN NORTH AMERICA

    EPA Science Inventory

    The hanging technique using Blue rayon, which specifically adsorbs mutagens with multicyclic planer structures, has advantages over the conventional method of bringing-large volumes of water back to the laboratory for extraction. Therefore, the analysis of many samples from remot...

  11. 40 CFR 414.26 - Pretreatment standards for new sources (PSNS).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 28 2010-07-01 2010-07-01 true Pretreatment standards for new sources (PSNS). 414.26 Section 414.26 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Rayon Fibers § 414.26...

  12. 40 CFR 414.24 - New source performance standards (NSPS).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 29 2014-07-01 2012-07-01 true New source performance standards (NSPS). 414.24 Section 414.24 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Rayon Fibers § 414.24 New source...

  13. 40 CFR 414.25 - Pretreatment standards for existing sources (PSES).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 29 2014-07-01 2012-07-01 true Pretreatment standards for existing sources (PSES). 414.25 Section 414.25 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Rayon Fibers § 414.25...

  14. 40 CFR 414.26 - Pretreatment standards for new sources (PSNS).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 29 2011-07-01 2009-07-01 true Pretreatment standards for new sources (PSNS). 414.26 Section 414.26 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Rayon Fibers § 414.26...

  15. 40 CFR 414.24 - New source performance standards (NSPS).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 30 2013-07-01 2012-07-01 true New source performance standards (NSPS). 414.24 Section 414.24 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Rayon Fibers § 414.24 New source...

  16. 40 CFR 414.25 - Pretreatment standards for existing sources (PSES).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 30 2012-07-01 2012-07-01 false Pretreatment standards for existing sources (PSES). 414.25 Section 414.25 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Rayon Fibers § 414.25...

  17. 40 CFR 414.24 - New source performance standards (NSPS).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 30 2012-07-01 2012-07-01 false New source performance standards (NSPS). 414.24 Section 414.24 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Rayon Fibers § 414.24 New source...

  18. 40 CFR 414.24 - New source performance standards (NSPS).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 28 2010-07-01 2010-07-01 true New source performance standards (NSPS). 414.24 Section 414.24 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Rayon Fibers § 414.24 New source...

  19. 40 CFR 414.25 - Pretreatment standards for existing sources (PSES).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 28 2010-07-01 2010-07-01 true Pretreatment standards for existing sources (PSES). 414.25 Section 414.25 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Rayon Fibers § 414.25...

  20. 40 CFR 414.26 - Pretreatment standards for new sources (PSNS).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 29 2014-07-01 2012-07-01 true Pretreatment standards for new sources (PSNS). 414.26 Section 414.26 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Rayon Fibers § 414.26...

  1. 40 CFR 414.26 - Pretreatment standards for new sources (PSNS).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 30 2012-07-01 2012-07-01 false Pretreatment standards for new sources (PSNS). 414.26 Section 414.26 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Rayon Fibers § 414.26...

  2. 40 CFR 414.25 - Pretreatment standards for existing sources (PSES).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 29 2011-07-01 2009-07-01 true Pretreatment standards for existing sources (PSES). 414.25 Section 414.25 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Rayon Fibers § 414.25...

  3. 40 CFR 414.24 - New source performance standards (NSPS).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 29 2011-07-01 2009-07-01 true New source performance standards (NSPS). 414.24 Section 414.24 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Rayon Fibers § 414.24 New source...

  4. 40 CFR 414.26 - Pretreatment standards for new sources (PSNS).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 30 2013-07-01 2012-07-01 true Pretreatment standards for new sources (PSNS). 414.26 Section 414.26 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Rayon Fibers § 414.26...

  5. 40 CFR 414.25 - Pretreatment standards for existing sources (PSES).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 30 2013-07-01 2012-07-01 true Pretreatment standards for existing sources (PSES). 414.25 Section 414.25 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Rayon Fibers § 414.25...

  6. Advanced Carbon Fabric/Phenolics for Thermal Protection Applications.

    DTIC Science & Technology

    1982-02-01

    structural properties are lower than rayon-based carbon fabriL analogues, they appear to be adequate for most ablative heat- shielding applications...34Development of Ablative Nozzles. Part II Ablative Nozzle Concept, Scaling Law , and Test Results," IAS Mtg. on Large Rockets, Sacramento, CA., Oct. 30

  7. East Europe Report, Political, Sociological and Military Affairs, No. 2170

    DTIC Science & Technology

    1983-07-25

    thoughts of the following. /Captain Kiril Popov,/ platoon commander: "Though in sharply critical but realistic form, the article is to my liking. It...callup other patrol sectors are denuded." /Maj Angel Dimitrov ,/ rayon administration deputy chief: "The article stirred up great interest among

  8. USSR Report, Science and Technology Policy.

    DTIC Science & Technology

    1986-01-10

    does not matter, things are going no worse. 153 At a farm near Moscow I saw a device which increases the impact of the machine milking of cows ...and reduces to naught the coming down with mastitis In our rayon flmost no one knows about this and other such innovations Who else but the managers

  9. 75 FR 7244 - Narrow Woven Ribbons with Woven Selvedge from the People's Republic of China: Preliminary...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-18

    .... (``Guangzhou Complacent''); Ningbo Huarui Import & Export Co., Ltd.; Ningbo Jinfeng Thread & Ribbon Co. Ltd... limited to nylon, polyester, rayon, polypropylene, and polyethylene teraphthalate), metal threads and/or... 13) or rubber thread; (4) narrow woven ribbons of a kind used for the manufacture of typewriter or...

  10. 40 CFR 414.91 - Toxic pollutant effluent limitations and standards for direct discharge point sources that use...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Direct Discharge Point Sources That...(k)fluoranthene 59 22 Benzo(a)pyrene 61 23 Bis(2-ethylhexyl) phthalate 279 103 Carbon Tetrachloride... Zinc for Rayon Fiber Manufacture that uses the viscose process and Acrylic Fiber Manufacture that uses...

  11. 40 CFR 414.91 - Toxic pollutant effluent limitations and standards for direct discharge point sources that use...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Direct Discharge Point Sources That...(k)fluoranthene 59 22 Benzo(a)pyrene 61 23 Bis(2-ethylhexyl) phthalate 279 103 Carbon Tetrachloride... Zinc for Rayon Fiber Manufacture that uses the viscose process and Acrylic Fiber Manufacture that uses...

  12. Molecular Orientation in Dry and Hydrated Cellulose Fibers: A Coherent Anti-Stokes Raman Scattering Microscopy Study

    PubMed Central

    Zimmerley, Maxwell; Younger, Rebecca; Valenton, Tiffany; Oertel, David C.; Ward, Jimmie L.; Potma, Eric O.

    2012-01-01

    Coherent anti-Stokes Raman scattering (CARS) microscopy is combined with spontaneous Raman scattering microspectroscopy and second harmonic generation (SHG) microscopy to interrogate the molecular alignment in dry and hydrated cellulose fibers. Two types of cellulose were investigated: natural cellulose I in cotton fibers and regenerated cellulose II in rayon fibers. On the basis of the orientation of the methylene symmetric stretching vibration, the molecular alignment of cellulose microfibrils is found to be conserved on the micrometer scale. Whereas the molecular orientation in cotton shows modest variability along the fiber, the alignment of the cellulose units in rayon is highly consistent throughout the fiber. The ordered alignment is retained upon fiber hydration. Upon hydration of the cellulose fibers, an anisotropic electronic contribution is observed, which indicates an ordered incorporation of water molecules into the fiber structure. The third-order and second-order electronic polarizability of cellulose I are directed along the axis of the polyglucan chain. No second-order optical response is observed in cellulose II, supporting the antiparallel arrangement of the polyglucan chains in regenerated cellulose. PMID:20684644

  13. Development of Advanced Conformal Ablative TPS Fabricated from Rayon- and PAN-Based Carbon Felts

    NASA Technical Reports Server (NTRS)

    Gasch, Matthew; Stackpoole, Margaret; White, Susan; Boghozian, Tane

    2016-01-01

    The conformal ablative TPS first developed under NASA's Hypersonics Project in the early 2000's demonstrated very low through the thickness conductivity compared to state-ofthe- art PICA. However, in initial arcjet testing of Conformal-1, surface recession rates were 2x higher than PICA. Because commercial carbon felts are currently available as very thin substrates, this was a concern if conformal TPS were to be considered for a mission that required thicker material. Discussed in this paper are the results of the development of an Advanced Conformal TPS derived from thicker, higher density carbon felt. Two substrate systems were evaluated, the first material was a needled rayon-based carbon felt and the other a needled PAN-based carbon felt. Both substrates were impregnated with phenolic resin following the PICA/CPICA process to add a low density phenolic matrix to the system prior to aerothermal screening at the LaRC HyMETS facility and larger scale testing in the NASA ARC Interaction Heating Facility (IHF) at heating fluxes ranging from 250-1700 W/cm2.

  14. Analyse de plomb dans les peintures

    NASA Astrophysics Data System (ADS)

    Broll, N.; Frezouls, J.-M.

    2002-07-01

    The analysis of lead in paints was previously used for the characterisation of pigments. In this way, the analysis is able to specify the century of the painting of a work of art. Recently this technique was also used to determine the toxicity of lead paints in building. This paper compared the result of several X-ray fluorescence spectrometer, either wave length/energy dispersion laboratory apparatus or X-ray microtube/radioactive source portable equipment's. L'analyse du plomb dans les peintures a jusqu'à présent été appliquée essentiellement pour caractériser les pigments lors de leur fabrication et pour identifier des rouvres d'art. Récemment cette technique est également utilisée pour déterminer la toxicité des peintures au plomb dans les bâtiments. Nous avons comparé les performances de plusieurs spectromètres de fluorescence X, soit de laboratoire à dispersion en longueur d'onde ou à dispersion en énergie (avec tube à rayonsX), soit portable avec source radioactive ou tube à rayons X.

  15. 77 FR 47363 - Narrow Woven Ribbons With Woven Selvedge From the People's Republic of China: Preliminary Results...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-08

    ..., polyester, rayon, polypropylene, and polyethylene teraphthalate), metal threads and/or metalized yarns, or... original length as defined in the (HTSUS, Section XI, Note 13) or rubber thread; (4) Narrow woven ribbons... comprised at least 85 percent by weight of threads having a denier of 225 or higher; (9) Narrow woven...

  16. 40 CFR 414.101 - Toxic pollutant effluent limitations and standards for direct discharge point sources that do not...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Direct Discharge Point Sources...(k)fluoranthene 47 19 Benzo(a)pyrene 48 20 Bis(2-ethylhexyl) phthalate 258 95 Carbon Tetrachloride... micrograms per liter. 2 Total Zinc for Rayon Fiber Manufacture that uses the viscose process and Acrylic...

  17. 40 CFR 414.101 - Toxic pollutant effluent limitations and standards for direct discharge point sources that do not...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Direct Discharge Point Sources...(k)fluoranthene 47 19 Benzo(a)pyrene 48 20 Bis(2-ethylhexyl) phthalate 258 95 Carbon Tetrachloride... micrograms per liter. 2 Total Zinc for Rayon Fiber Manufacture that uses the viscose process and Acrylic...

  18. Characterization of the interface between cellulosic fibers and a thermoplastic matrix

    Treesearch

    Feipeng P. Liu; Michael P. Wolcott; Douglas J. Gardner; Timothy G. Rials

    1994-01-01

    The applicability of the microbond test to evaluate the interfacial properties between cellulosic fibers and thermoplastics was studied. Acetylation and beat treatment were applied to modify the surface of cellulosic fibers (rayon, cotton, and wood). The apparent diameters and surface free energies of the fibers were estimated by dynamic contact angle (DCA) analysis....

  19. 16 CFR 303.7 - Generic names and definitions for manufactured fibers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... least 85% by weight of lactic acid ester units derived from naturally occurring sugars. (Sec. 6, 72 Stat... composed of at least 85% by weight of an ester of a substituted aromatic carboxylic acid, including but not... description of the fiber. (d) Rayon.A manufactured fiber composed of regenerated cellulose, as well as...

  20. 16 CFR 303.7 - Generic names and definitions for manufactured fibers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... least 85% by weight of lactic acid ester units derived from naturally occurring sugars. (Sec. 6, 72 Stat... composed of at least 85% by weight of an ester of a substituted aromatic carboxylic acid, including but not... description of the fiber. (d) Rayon.A manufactured fiber composed of regenerated cellulose, as well as...

  1. 16 CFR 303.7 - Generic names and definitions for manufactured fibers.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... least 85% by weight of lactic acid ester units derived from naturally occurring sugars. (Sec. 6, 72 Stat... composed of at least 85% by weight of an ester of a substituted aromatic carboxylic acid, including but not... description of the fiber. (d) Rayon.A manufactured fiber composed of regenerated cellulose, as well as...

  2. 16 CFR 303.7 - Generic names and definitions for manufactured fibers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... least 85% by weight of lactic acid ester units derived from naturally occurring sugars. (Sec. 6, 72 Stat... composed of at least 85% by weight of an ester of a substituted aromatic carboxylic acid, including but not... description of the fiber. (d) Rayon.A manufactured fiber composed of regenerated cellulose, as well as...

  3. A pilot-scale nonwoven roll goods manufacturing process reduces microbial burden to pharmacopeia acceptance levels for nonsterile hygiene applications

    USDA-ARS?s Scientific Manuscript database

    A total of seven source fiber types were selected for use in the manufacturing of nonwoven roll goods: polyester; polypropylene; rayon; greige cotton from two sources; mechanically cleaned greige cotton; and scoured and bleached cotton. The microbial burden of each source fiber was measured as a pr...

  4. Evaluation of swabs and transport media for the recovery of ...

    EPA Pesticide Factsheets

    Journal Article Two Y. pestis strains (virulent and avirulent), four swab types (polyester, macrofoam, rayon, and cotton), two pre-moistening solutions, six transport media, three temperatures, two levels of organic load, and four processing methods were evaluated to determine the conditions that would yield the highest percent of cultivable Y. pestis cells after storage.

  5. 46 CFR 164.023-3 - Specifications and standards incorporated by reference.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Weathering Method—164.023-7. Federal Specifications (4) V-T-285E—Thread, Polyester, August 21, 1986—164.023-5..., Polyester Core: Cotton-, Rayon-, or Polyester-Covered, September 30, 1986—164.023-5. (7) MIL-T-43624A—Thread, Polyester, Spun, January 22, 1982—164.023-5. (c) All reference materials are available from the Naval...

  6. 46 CFR 164.023-3 - Specifications and standards incorporated by reference.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Weathering Method—164.023-7. Federal Specifications (4) V-T-285E—Thread, Polyester, August 21, 1986—164.023-5..., Polyester Core: Cotton-, Rayon-, or Polyester-Covered, September 30, 1986—164.023-5. (7) MIL-T-43624A—Thread, Polyester, Spun, January 22, 1982—164.023-5. (c) All reference materials are available from the Naval...

  7. USSR Report, Agriculture

    DTIC Science & Technology

    1984-06-05

    The linking module may be a methane tank, processing manure of the livestock complex into biogas and fertilizer. Biogas is good for generating...As already noted, the beef production process under conditions of interfarm cooperation is broken down into two independent stages ? reproduction at...hectare must be obtained. Such have been the yields obtained at the 40 Let Oktyabrya Kolkhoz in Stolinskiy Rayon. However, during two - stage harvesting

  8. Proceedings: Nozzle Initiative Industry Advisory Committee on Standardization of Carbon-Phenolic Test Methods and Specifications

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The proceedings of the meeting is presented in conversational form. Some areas of discussion are as follow: resin advancement at NASA Marshall new technologies studies; NMR studies; SPIP/PAN development summary; computer modeling support; composite testing; carbon assay testing; activity and aerospace computer database; alternate rayon yarn sizing; fiber morphology; and carbon microballoons specifications.

  9. Syntrophic co-culture of Bacillus subtilis and Klebsiella pneumonia for degradation of kraft lignin discharged from rayon grade pulp industry.

    PubMed

    Yadav, Sangeeta; Chandra, Ram

    2015-07-01

    In order to search the degradability of kraft lignin, the potential bacterial strains Bacillus subtilis (GU193980) and Klebsiella pneumoniae (GU193981) were isolated, screened and applied in axenic and co-culture conditions. Results revealed that mixed culture showed better decolorization efficiency (80%) and reduction of pollution parameters (COD 73% and BOD 62%) than axenic culture. This indicated syntrophic growth of these two bacteria rather than any antagonistic effect. The HPLC analysis of degraded samples of kraft lignin has shown the reduction in peak area compared to control, suggesting that decrease in color intensity might be largely attributed to the degradation of lignin by isolated bacteria. Further, the GC-MS analysis showed that most of the compounds detected in control were diminished after bacterial treatment. Further, the seed germination test using Phaseolus aureus has supported the detoxification of bacterial decolorized kraft lignin for environmental safety. All these observations have revealed that the developed bacterial co-culture was capable for the effective degradation and decolorization of lignin containing rayon grade pulp mill wastewater for environmental safety. Copyright © 2015. Published by Elsevier B.V.

  10. Level 3 material characterization of NARC HRPF, HRHU, HRHF, and HRPU

    NASA Technical Reports Server (NTRS)

    Tobias, Mark E.

    1993-01-01

    The North American Rayon Corporation (NARC) precursor was developed, qualified, and characterized for Space Shuttle nozzle carbon-cloth phenolic ablative materials in three distinct phases. The characterization phase includes thermal and structural material property analysis and comparisons. This report documents the thermal and structural material property characterization performed by Southern Research Institute (SRI) on the two NARC baseline and two crossover materials.

  11. JPRS Report: East Europe.

    DTIC Science & Technology

    1991-07-23

    Agrarian National Union, the Fatherland Front, the Dimitrov Communist Youth Union, the Conference of Indepen- dent Syndicalists in Bulgaria, the ABP...BCP Committee); Kiril Simeonov, director (former high official within the Kolarov Rayon BCP Committee and former paid party secretary at the ZMM in...in charge of the firm’s fire- fighters; Stayko Stoyanov, former Sofia City BCP Com- mittee secretary; Mariyka Lazarova, wife of Kiril Lazarov

  12. Evaluation of swabs and transport media for the recovery of Yersinia pestis.

    PubMed

    Gilbert, Sarah E; Rose, Laura J; Howard, Michele; Bradley, Meranda D; Shah, Sanjiv; Silvestri, Erin; Schaefer, Frank W; Noble-Wang, Judith

    2014-01-01

    The Government Accountability Office report investigating the surface sampling methods used during the 2001 mail contamination with Bacillus anthracis brought to light certain knowledge gaps that existed regarding environmental sampling with biothreat agents. Should a contamination event occur that involves non-spore forming biological select agents, such as Yersinia pestis, surface sample collection and processing protocols specific for these organisms will be needed. Two Y. pestis strains (virulent and avirulent), four swab types (polyester, macrofoam, rayon, and cotton), two pre-moistening solutions, six transport media, three temperatures, two levels of organic load, and four processing methods (vortexing, sonicating, combined sonicating and vortexing, no agitation) were evaluated to determine the conditions that would yield the highest percent of cultivable Y. pestis cells after storage. The optimum pre-moistening agent/transport media combination varied with the Y. pestis strain and swab type. Directly inoculated macrofoam swabs released the highest percent of cells into solution (93.9% recovered by culture) and rayon swabs were considered the second best swab option (77.0% recovered by culture). Storage at 4°C was found to be optimum for all storage times and transport media. In a worst case scenario, where the Y. pestis strain is not known and sample processing and analyses could not occur until 72h after sampling, macrofoam swabs pre-moistened with PBS supplemented with 0.05% Triton X-100 (PBSTX), stored at 4°C in neutralizing buffer (NB) as a transport medium (PBSTX/NB) or pre-moistened with NB and stored in PBSTX as a transport medium (NB/PBSTX), then vortexed 3min in the transport medium, performed significantly better than all other conditions for macrofoam swabs, regardless of strain tested (mean 12 - 72h recovery of 85.9-105.1%, p<0.001). In the same scenario, two combinations of pre-moistening medium/transport medium were found to be optimal for rayon swabs stored at 4°C (p<0.001), then sonicated 3min in the transport medium; PBSTX/PBSTX and NB/PBSTX (mean 12-72h recovery of 83.7-110.1%). © 2013.

  13. JPRS Report. Soviet Union: Political Affairs.

    DTIC Science & Technology

    1990-09-13

    certain sense. Only by tackling a specific job and receiving a certain number of "bruises" and "lumps" while performing that job can one acquire the...women for the most part are performing ideological work in republic party committees: women comprise approximately 80 percent of rayon, city, and...population. Particular indignation is aroused by articles on this provocational topic by learned gentlemen with academic degrees, persons whom, one would

  14. FLOQSwab™: Optimisation of Procedures for the Recovery of Microbiological Samples from Surfaces

    PubMed Central

    Finazzi, Guido; Losio, Marina Nadia; Varisco, Giorgio

    2016-01-01

    The FLOQSwab™ is a specimen collection device worldwide recognised for its superior performance in the clinical diagnostics. The aim of this work was to evaluate FLOQSwab™ for the recovery of microbiological samples from surfaces compared to the traditional swab (rayon tipped swab) as per ISO 18593:2004 standard. The FLOQSwab™, thanks to its innovative manufacturing technology, allows improving the efficiency of recovery and release of analyte. The study has been divided into two experiments. In the first experiment the two swabs were evaluated for their capacity to recover and release the analyte (three different bacterial loads of Escherichia coli). In the second experiment, the two swabs were evaluated for their capacity to recover three different bacterial loads of E. coli from two different surface materials (stainless steel and polypropylene). In all experiments the flocked swab demonstrated a higher recovery rate compared to the traditional rayon tipped swab. The data obtained from this preliminary study demonstrated that the FLOQSwab™ could be a good food surfaces collection device, which improves the recovery of the analyte and thus produces accurate results. Based on the outcomes of the study, a larger field study is in progress using the FLOQSwab™ for samples collection to improve both environmental monitoring and the efficacy of the hygiene controls for food safety. PMID:27853708

  15. Comparison of vaginal microbiota sampling techniques: cytobrush versus swab.

    PubMed

    Mitra, Anita; MacIntyre, David A; Mahajan, Vishakha; Lee, Yun S; Smith, Ann; Marchesi, Julian R; Lyons, Deirdre; Bennett, Phillip R; Kyrgiou, Maria

    2017-08-29

    Evidence suggests the vaginal microbiota (VM) may influence risk of persistent Human Papillomavirus (HPV) infection and cervical carcinogenesis. Established cytology biobanks, typically collected with a cytobrush, constitute a unique resource to study such associations longitudinally. It is plausible that compared to rayon swabs; the most commonly used sampling devices, cytobrushes may disrupt biofilms leading to variation in VM composition. Cervico-vaginal samples were collected with cytobrush and rayon swabs from 30 women with high-grade cervical precancer. Quantitative PCR was used to compare bacterial load and Illumina MiSeq sequencing of the V1-V3 regions of the 16S rRNA gene used to compare VM composition. Cytobrushes collected a higher total bacterial load. Relative abundance of bacterial species was highly comparable between sampling devices (R 2  = 0.993). However, in women with a Lactobacillus-depleted, high-diversity VM, significantly less correlation in relative species abundance was observed between devices when compared to those with a Lactobacillus species-dominant VM (p = 0.0049). Cytobrush and swab sampling provide a comparable VM composition. In a small proportion of cases the cytobrush was able to detect underlying high-diversity community structure, not realized with swab sampling. This study highlights the need to consider sampling devices as potential confounders when comparing multiple studies and datasets.

  16. The Design and Testing of a Dual Fiber Textile Matrix for Accelerating Surface Hemostasis

    PubMed Central

    Fischer, Thomas H.; Vournakis, John N.; Manning, James E.; McCurdy, Shane L.; Rich, Preston B.; Nichols, Timothy C.; Scull, Christopher M.; McCord, Marian G.; Decorta, Joseph A.; Johnson, Peter C.; Smith, Carr J.

    2011-01-01

    The standard treatment for severe traumatic injury is frequently compression and application of gauze dressing to the site of hemorrhage. However, while able to rapidly absorb pools of shed blood, gauze fails to provide strong surface (topical) hemostasis. The result can be excess hemorrhage-related morbidity and mortality. We hypothesized that cost-effective materials (based on widespread availability of bulk fibers for other commercial uses) could be designed based on fundamental hemostatic principles to partially emulate the wicking properties of gauze while concurrently stimulating superior hemostasis. A panel of readily available textile fibers was screened for the ability to activate platelets and the intrinsic coagulation cascade in vitro. Type E continuous filament glass and a specialty rayon fiber were identified from the material panel as accelerators of hemostatic reactions and were custom woven to produce a dual fiber textile bandage. The glass component strongly activated platelets while the specialty rayon agglutinated red blood cells. In comparison with gauze in vitro, the dual fiber textile significantly enhanced the rate of thrombin generation, clot generation as measured by thromboelastography, adhesive protein adsorption and cellular attachment and activation. These results indicate that hemostatic textiles can be designed that mimic gauze in form but surpass gauze in ability to accelerate hemostatic reactions. PMID:19489008

  17. USSR Report, Agriculture

    DTIC Science & Technology

    1984-05-22

    organizational and agro- technical measures will enable us, in our opinion, to produce an average of 37-38 quintals of corn grain per hectare and to...average of 322 quintals of roots and to produce 32-33 quintals of sugar per hectare. They are up to this task. The essential foundation for the...of seed -- or 4.8 quintals per hectare. In 1983 the Zarya Kolkhoz in Krasnogvardeyskiy Rayon in Stavropol Kray obtained 3.5 quintals of seed from

  18. Translations on USSR Military Affairs, Number 1374

    DTIC Science & Technology

    1978-09-05

    film sequence, the viewer is supposed to note these mistakes and inform the studio how one should proceed correctly in the specific situation. ’This...enthusiastically to the quiz program. The studio received more than 5,000 letters. The panel of judges, headed by the chief of Lithuanian SSR Civil Defense...scripts or broadcast texts which are literally copied from instructions and textbooks. Rayon, city and enterprise radio studios do much to promote

  19. USSR Report, Agriculture.

    DTIC Science & Technology

    1986-10-03

    ZHIZN, 8 Aug 86) . . 8 LIVESTOCK Oblast, Rayon Indicators for Milk Production, Meat Sales in Belorussian Kolkhozes, Sovkhozes, 1 July 1986...affecting the growth and development of the vegetable crops. The cucumbers are blossoming in all areas and flesh- colored ripeness has been observed in...husbandry serves as a leading branch of agricultural production, D^iv?f ij ?£ t5eir P,UnS f°r Sellin8 milk and meat to th* state. The productivity

  20. JPRS Report Soviet Union Political Affairs.

    DTIC Science & Technology

    1990-07-20

    revenues and securing the transfer to self - financing..." (paragraph 38). So to whom, in such a case, does the CPSU Perovskiy Raykom (Rayon...views. However, in this instance the principle of the right of nations to self -determination (up to and including seces- sion) is transformed into a...division of authority carried out? What does this give to the local agencies of self - government and to the center? All this deserves atten- tion. There

  1. JPRS Report, Soviet Union: Political Affairs.

    DTIC Science & Technology

    1989-06-08

    L.I. such issues. Brezhnev is mentioned in the section "Decorations" as a record -holder in the number of decorations. How many [Shcherban] Finally, can...these difficulties and conflicts started to assume what was in many respects an artificially caused nature. This concept includes a content that differs...Dzerzhinskiy and some other rayon in anticipation of the day when many Moscovites- residents to make a mockery of the elections and scratch myself included -once

  2. Current and historical individual data about exposure of workers in the rayon industry to carbon disulfide and their validity in calculating the cumulative dose.

    PubMed

    Göen, Thomas; Schramm, Axel; Baumeister, Thomas; Uter, Wolfgang; Drexler, Hans

    2014-08-01

    The objective of the study was to investigate how exposure to carbon disulfide (CS2) in a rayon-manufacturing plant has changed within two decades and whether it is possible to calculate valid data for the individual cumulative exposure. The data for CS2 concentration in air and biological exposure monitoring (2-thio-1,3-thiaxolidine-4-carboxylic acid (TTCA) in urine) from two cross-sectional studies, performed in 1992 (n = 362) and 2009 (n = 212) in a German rayon-manufacturing plant, were compared to data obtained from company-internal measurements between the studies. Using the data from the cross-sectional studies and company-internal data, cumulative external exposure and the cumulative internal exposure were calculated for each worker. External and internal CS2 exposure of the employees decreased from 1992 (medians 4.0 ppm and 1.63 mgTTCA/g creatinine) to 2009 (medians 2.5 ppm and 0.86 mg/g). However, company-internal CS2 data do not show a straight trend for this period. The annual medians of the company-internal measurement of external exposure to CS2 have varied between 2.7 and 8.4 ppm, in which median values exceeded 5 ppm generally since 2000. The annual medians for the company-internal biomonitoring assessment ranged between 1.2 and 2.8 mg/g creatinine. The cumulative CS2 exposure ranged from 8.5 to 869.5 ppm years for external exposure and between 1.30 and 176.2 mg/g creatinine years for the internal exposure. Significant correlations were found between the current air pollution and the internal exposure in 2009 but also between the cumulative external and internal CS2 exposure. Current exposure data, usually collected in cross-sectional studies, rarely allow a reliable statement on the cumulative dose, because of higher exposure in the past and of fluctuating courses of exposure. On the other hand, company-internal exposure data may be affected by non-representative measurement strategies. Some verification of the reliability of cumulative exposure data may be possible by testing the correlation between cumulative exposure data of external assessment and biological monitoring.

  3. Advanced Clothing Studies

    NASA Technical Reports Server (NTRS)

    Orndoff, Evelyne; Poritz, Darwin

    2014-01-01

    All human space missions require significant logistical mass and volume that add an unprecedented burden on longduration missions beyond low-Earth orbit. For these missions with limited cleaning resources, a new wardrobe must be developed to reduce this logistical burden by reducing clothing mass and extending clothing wear. The present studies have been undertaken, for the first time, to measure length of wear and to assess the acceptance of such extended wear. Garments in these studies are commercially available exercise T-shirts and shorts, routine-wear T-shirts, and longsleeved pullover shirts. Fabric composition (cotton, polyester, light-weight, superfine Merino wool, modacrylic, cotton/rayon, polyester/Cocona, modacrylic/Xstatic, modacrylic/rayon, modacrylic/lyocell/aramid), construction (open knit, tight knit, open weave, tight weave), and finishing treatment (none, quaternary ammonium salt) are the independent variables. Eleven studies are reported here: five studies of exercise T-shirts, three of exercise shorts, two of routine wear Tshirts, and one of shirts used as sleep-wear. All studies are conducted in a climate-controlled environment, similar to a space vehicle's. For exercise clothing, study participants wear the garments during aerobic exercise. For routine wear clothing, study participants wear the T-shirts daily in an office or laboratory. Daily questionnaires collected data on ordinal preferences of nine sensory elements and on reason for retiring a used garment. Study 1 compares knitted cotton, polyester, and Merino exercise T-shirts (61 participants), study 2, knitted polyester, modacrylic, and polyester/Cocona exercise T-shirts (40 participants), study 3, cotton and polyester exercise shorts, knitted and woven (70 participants), all three using factorial experimental designs with and without a finishing treatment, conducted at the Johnson Space Center, sharing study participants. Study 4 compares knitted polyester and ZQ Merino exercise T-shirts, study 5, knitted ZQ Merino and modacrylic routine-wear T-shirts, with study 6 using only knitted polyester exercise shorts. No finishing treatment is used. Studies 4 and 5 use cross-over experimental designs, and all three studies were conducted aboard the ISS with six crew. Studies 4 and 6 were repeated on the ground with the same participants to learn if perception was affected microgravity. Study 7 is a longer-term, single-blind panel study of knitted routine-wear undershirts with at least 12 participants to assess tolerance to Merino by comparing it with a cotton/rayon blends, using a cross-over design, eliminating carryover effects with wash-out periods between shirts.

  4. La determination du rayon terrestre par J. PICARD en 1669 1671

    NASA Astrophysics Data System (ADS)

    Levallois, J. J.

    1983-03-01

    The French astronomer Jean PICARD (1620 1682) was certainly one of the leading scientists of his time. Friend of Huygens, of Hevelius, of Oldenburg, master of Römer, indefatigable traveller, he played a very important part in the development of positional astronomy and geodesy. - He first, had the idea of comparing the length units to a reproductible physical quantity, namely the length of the one second pendulum at Paris, and measured that length.

  5. JPRS Report Soviet Union Political Affairs.

    DTIC Science & Technology

    1990-06-25

    this is far from the truth. I must say that among the USSR Supreme Soviet depu- ties there are a few people who feel that the Union is being torn...pioneer camps; — investigate the feasibility of and organize the rest of children and young families from the afflicted rayons in their own republics...republic com- munist parties will create their own specific documents. I feel that we must voice the same decisive attitude toward the attempts to weaken

  6. Modeling Gas Bubble Behaviour and Loading on a Rigid Target due to Close-Proximity Underwater Explosions: Comparison to Tests Conducted at DRDC Suffield

    DTIC Science & Technology

    2010-11-01

    rayon de bulle de type champ libre, d’une cible rigide. À cette distance de sécurité, l’onde de choc et la bulle de gaz contribuent de façon...produisent des prédictions d’impulsion améliorées pour les cibles rigides. DRDC Atlantic TM 2010-238 iii Executive summary Modeling...i Executive summary

  7. Space Shuttle Projects

    NASA Image and Video Library

    2002-08-01

    A scaled-down 24-inch version of the Space Shuttle's Reusable Solid Rocket Motor was successfully fired for 21 seconds at a Marshall Space Flight Center (MSFC) Test Stand. The motor was tested to ensure a replacement material called Lycocel would meet the criteria set by the Shuttle's Solid Motor Project Office. The current material is a heat-resistant, rayon-based, carbon-cloth phenolic used as an insulating material for the motor's nozzle. Lycocel, a brand name for Tencel, is a cousin to rayon and is an exceptionally strong fiber made of wood pulp produced by a special "solvent-spirning" process using a nontoxic solvent. It will also be impregnated with a phenolic resin. This new material is expected to perform better under the high temperatures experienced during launch. The next step will be to test the material on a 48-inch solid rocket motor. The test, which replicates launch conditions, is part of Shuttle's ongoing verification of components, materials, and manufacturing processes required by MSFC, which oversees the Reusable Solid Rocket Motor project. Manufactured by the ATK Thiokol Propulsion Division in Promontory, California, the Reusable Solid Rocket Motor measures 126 feet (38.4 meters) long and 12 feet (3.6 meters) in diameter. It is the largest solid rocket motor ever flown and the first designed for reuse. During its two-minute burn at liftoff, each motor generates an average thrust of 2.6 million pounds (1.2 million kilograms).

  8. Comparison of occupational exposure to carbon disulphide in a viscose rayon factory before and after technical adjustments.

    PubMed

    Bulat, Petar; Daemen, Edgard; Van Risseghem, Marleen; De Bacquer, Dirk; Tan, Xiaodong; Braeckman, Lutgart; Vanhoorne, Michel

    2002-01-01

    The objective of this follow-up study was to verify the efficacy of the technical adjustments gradually introduced in departments of a viscose rayon factory from 1989 onward. Personal exposure to carbon disulphide was assessed by means of personal monitoring through active sampling. Six job titles in three departments of the factory were sampled. Geometric means were calculated and used as estimates of time-weighted average (TWA) concentrations. The results from the present study were compared with similar measurements from a previous study in the same factory. Due to organizational changes, only three job titles (spinner, first spinner, and viscose preparator) could be compared directly. Two new job titles were identified, although tasks performed in these two job titles already existed. The measurements from one job title could not be compared, due to a substantial reorganization and automation of the tasks carried out in the department. The comparison before and after technical improvements shows that personal exposure of spinner and first spinner has been substantially reduced. Even the geometric means of measurements outside the fresh air mask are below the TWA-TLV (Threshold Limit Value). Despite the difficulties in comparing the results from the two studies, it is concluded that the technical measures reduced up to tenfold personal exposure to carbon disulphide and personal protection reduced it further by a factor two.

  9. Fine Structure of Diffuse Scattering Rings in Al-Li-Cu Quasicrystal: A Comparative X-ray and Electron Diffraction Study

    NASA Astrophysics Data System (ADS)

    Donnadieu, P.; Dénoyer, F.

    1996-11-01

    A comparative X-ray and electron diffraction study has been performed on Al-Li-Cu icosahedral quasicrystal in order to investigate the diffuse scattering rings revealed by a previous work. Electron diffraction confirms the existence of rings but shows that the rings have a fine structure. The diffuse aspect on the X-ray diffraction patterns is then due to an averaging effect. Recent simulations based on the model of canonical cells related to the icosahedral packing give diffractions patterns in agreement with this fine structure effect. Nous comparons les diagrammes de diffraction des rayon-X et des électrons obtenus sur les mêmes échantillons du quasicristal icosaèdrique Al-Li-Cu. Notre but est d'étudier les anneaux de diffusion diffuse mis en évidence par un travail précédent. Les diagrammes de diffraction électronique confirment la présence des anneaux mais ils montrent aussi que ces anneaux possèdent une structure fine. L'aspect diffus des anneaux révélés par la diffraction des rayons X est dû à un effet de moyenne. Des simulations récentes basées sur la décomposition en cellules canoniques de l'empilement icosaédrique produisent des diagrammes de diffraction en accord avec ces effects de structure fine.

  10. Qualitative assessment of vaginal microflora during use of tampons of various compositions.

    PubMed Central

    Onderdonk, A B; Zamarchi, G R; Rodriguez, M L; Hirsch, M L; Muñoz, A; Kass, E H

    1987-01-01

    The effect of vaginal tampons on the microbial flora during menstruation has recently been studied by several investigators. However, little information regarding the qualitative effects attributable to particular tampon fibers is available. The purpose of the present study was to compare the effects of polyacrylate rayon tampons and cotton-viscose rayon blend tampons on the qualitative bacterial counts obtained from tampons and concomitant vaginal swabs and to determine whether either of these tampon types alters the qualitative makeup of the vaginal microflora when compared with the microflora in the same women using all-cotton tampons or external catamenial pads. Tampon and swab samples were obtained as described previously (A. B. Onderdonk, G. R. Zamarchi, M. L. Rodriguez, M. L. Hirsch, A. Muñoz, and E. H. Kass, Appl. Environ. Microbiol. 53:2774-2778). The genus and species of the six dominant bacterial species in each sample were identified, if possible. A statistical evaluation of the qualitative makeup of the microflora revealed that the same numerically dominant phenotypes were present regardless of sample type, sample time, or catamenial product. Predictable changes in total numbers among the dominant species were also noted when the data were evaluated by day of menstrual cycle. The correlation between the total numbers of each dominant species present was evaluated by day of cycle, and the findings are discussed. PMID:3435143

  11. Étude de la structure des alliages vitreux Ag-As2S3 par diffraction de rayons X

    NASA Astrophysics Data System (ADS)

    Popescu, M.; Sava, F.; Cornet, A.; Broll, N.

    2002-07-01

    The structure of several silver alloyed arsenic chalocgenide has been determined by X-ray diffraction. For low silver doping the disordered layer structure, characteristic to the glassy AS2S3 is retained as demonstrated by the well developed first sharp diffraction peak in the X-ray diffraction pattern. For high amount of silver introduced in the As2S3 matrix, the disoredered layer configurations disappear, as shown by the diminishing and even disappearance of the first sharp diffraction peak in the X-ray patterns. A three-dimensional structure based on Ag2S -type configuration is formed. La structure de quelques alliages sulfure d'arsenic - argent a été determinée par diffraction de rayons X. Pour de faibles dopages à l'argent on conserve la structure desordonnées caractéristique des couches atomique d'As2S3 vitreux ; ceci est prouvé par la forte intensité du premier pic étroit de diffraction. Pour des plus grandes proportions d'argent la structure de l'alliage vitreux fait apparaître des unités structurales caractéristiques du cristal d'Ag2S et la configuration atomique avec des couches desordonnées disparaît (le premier pic étroit de diffraction s'évanouit) en faisant place à une structure tridimensionelle.

  12. Developpement et validation d'un outil base sur l'acoustique geometrique pour le diagnostic du bruit de nacelle

    NASA Astrophysics Data System (ADS)

    Minard, Benoit

    De nos jours, la problématique du bruit généré par les avions est devenue un point de développement important dans le domaine de l'aéronautique. C'est ainsi que de nombreuses études sont faites dans le domaine et une première approche consiste à modéliser de façon numérique ce bruit de manière à réduire de façon conséquente les coûts lors de la conception. C'est dans ce contexte qu'un motoriste a demandé à l'université de Sherbrooke, et plus particulièrement au groupe d'acoustique de l'Université de Sherbrooke (GAUS), de développer un outil de calcul de la propagation des ondes acoustiques dans les nacelles mais aussi pour l'étude des effets d'installation. Cet outil de prédiction leur permet de réaliser des études afin d'optimiser les traitements acoustiques (« liners »), la géométrie de ces nacelles pour des études portant sur l'intérieur de la nacelle et des études de positionnement des moteurs et de design pour les effets d'installation. L'objectif de ce projet de maîtrise était donc de poursuivre le travail réalisé par [gousset, 2011] sur l'utilisation d'une méthode de lancer de rayons pour l'étude des effets d'installation des moteurs d'avion. L'amélioration du code, sa rapidité, sa fiabilité et sa généralité étaient les objectifs principaux. Le code peut être utilisé avec des traitements acoustiques de surfaces («liners») et peut prendre en compte le phénomène de la diffraction par les arêtes et enfin peut être utilisé pour réaliser des études dans des environnements complexes tels que les nacelles d'avion. Le code développé fonctionne en 3D et procéde en 3 étapes : (1) Calcul des faisceaux initiaux (division d'une sphère, demi-sphère, maillage des surfaces de la géométrie) (2) Propagation des faisceaux dans l'environnement d'étude : calcul de toutes les caractéristiques des rayons convergents (amplitude, phase, nombre de réflexions, ...) (3) Reconstruction du champ de pression en un ou plusieurs points de l'espace à partir de rayons convergents (sommation des contributions de chaque rayon) : sommation cohérente. Le code (GA3DP) permet de prendre en compte les traitements de surface des parois, la directivité de la source, l'atténuation atmosphérique et la diffraction d'ordre 1. Le code a été validé en utilisant différentes méthodes telles que la méthode des sources-images, la méthode d'analyse modale ou encore la méthode des éléments finis de frontière. Un module Matlab a été créé spécialement pour l'étude des effets d'installation et intégré au code existant chez Pratt & Whitney Canada. Mots-clés : Acoustique géométrique - Ray-Tracing - Lancer de faisceaux - Diffraction - Sommation Cohérente - Niveau de Pression.

  13. USSR Report, Agriculture.

    DTIC Science & Technology

    1984-06-12

    Krasnokutskiy Rayon. Its silvery cupola gleamed behind the cow sheds and sil- age trenches. The new storage facility was one-half lower, but twice as...in individual republics during 1982 are shown in the table. The productivity of cows in 1982 totaled 2619 kg, which was J4I6 kg, or 19 percent more...than on the nation’s kolkhozes and sovkhozes; output per man-hour was 1.6 times higher, and calf-production per 100 cows was up by 2 calves. The best

  14. The Evaluation of Activated Carbon as an Anti-Vesicant Agent in Protective Clothing

    DTIC Science & Technology

    1944-07-03

    of the desirable properties Riscussed above. In addition to the CWS-N 44 carbon, which is made from wood flour, MSA-Gl, a coconut base carbon, and...Cu, Ag, and Cr. MSA-G 1 Base Activated coconut charcoal HSA-GI Type ASC MSA-GI Base chemically impregnated with salts of Cu, Ag, and Cr. PCI-Pn.I...threads in which the rayon fibres contained carbon. Out- door exposure of such cloths up to six months showed that the protective capacity was not

  15. Military Uniforms: Issues Related to the Supply of Flame Resistant Fibers for the Production of Military Uniforms

    DTIC Science & Technology

    2011-06-30

    fibers. A variety of fibers may be used to create a fabric blend, including FR rayon, Nomex®, Twaron®, Kevlar®, FR cotton, polybenzimidazole ( PBI ...as meta-aramids (e.g., Nomex®), modacrylic, PBI , and FR-treated cotton. o For example, the Army is currently testing fabrics in an attempt to...considering fabric blends containing FR-treated cotton as a potential alternative. o The Marine Corps uses PBI fibers in its balaclava (a protective

  16. Optical Propagation in the Atmosphere

    DTIC Science & Technology

    1976-05-01

    I (r~) oil v out la friquance, r Is rayon...diroctement transmis des sources. La fux et n a pont ~)A travers un plan perpondiculairo I la direction i ~sera F (4r) co 44, (3) -Fgý’r) F- (’r) (4 oil F...forme oil la fonction source J s𔄀crit ;0(r) 4. JOU~ - I p(’r;4,’n’) I (’r,ý’) dwt +’(.r*,4) + (1-w (r)) B(r) ; (6) 1. premier terms correspond

  17. Analytical Solutions for Predicting Underwater Explosion Gas Bubble Behaviour

    DTIC Science & Technology

    2010-11-01

    donne les meilleures prévisions comparativement aux ajustements avec les données expérimentales. Le modèle à fluide incompressible exige d’utiliser une...couplage des mouvements radial et migratoire. L’étude montre que, comparativement aux résultats d’expérience, la réduction du rayon de la bulle... comparativement aux ajustements avec les données expérimentales. Le modèle à fluide incompressible exige d’utiliser une fonction empirique de perte d’énergie

  18. JPRS Report, Soviet Union, Political Affairs.

    DTIC Science & Technology

    1988-12-21

    office in Kirovskiy rayon recorded the marriage of an 18-year-old girl to a 78-year-old man. Out of ethical considerations we shall not name the names...for us to produce panty hose of other sizes: 12-14 for children and 29-33 for women. This is caused by a lack of equipment. In addition, the factory...time but has still not been resolved. "Our nation does not produce the equipment at all for making cotton panty hose in the large sizes. The only

  19. Evaluation of sprayed hypochlorous acid solutions for their virucidal activity against avian influenza virus through in vitro experiments.

    PubMed

    Hakim, Hakimullah; Thammakarn, Chanathip; Suguro, Atsushi; Ishida, Yuki; Kawamura, Akinobu; Tamura, Miho; Satoh, Keisuke; Tsujimura, Misato; Hasegawa, Tomomi; Takehara, Kazuaki

    2015-02-01

    Hypochlorous acid (HOCl) solutions were evaluated for their virucidal ability against a low pathogenic avian influenza virus (AIV), H7N1. HOCl solutions containing 50, 100 and 200 ppm chlorine (pH 6) or their sprayed solutions (harvested in dishes placed at 1 or 30 cm distance between the spray nozzle and dish) were mixed with the virus with or without organic materials (5% fetal bovine serum: FBS). Under plain diluent conditions (without FBS), harvested solutions of HOCl after spraying could decrease the AIV titer by more than 1,000 times, to an undetectable level (< 2.5 log10TCID50/ml) within 5 sec, with the exception of the 50 ppm solution harvested after spraying at the distance of 30 cm. Under the dirty conditions (in the presence of 5% FBS), they lost their virucidal activity. When HOCl solutions were sprayed directly on the virus on rayon sheets for 10 sec, the solutions of 100 and 200 ppm could inactivate AIV immediately after spraying, while 50 ppm solution required at least 3 min of contact time. In the indirect spray form, after 10 sec of spraying, the lids of the dishes were opened to expose the virus on rayon sheets to HOCl. In this form, the 200 ppm solution inactivated AIV within 10 min of contact, while 50 and 100 ppm could not inactivate it. These data suggest that HOCl can be used in spray form to inactivate AIV at the farm level.

  20. Avant Propos

    NASA Astrophysics Data System (ADS)

    Cornet, Alain; Broll, Norbert; Denier, Philippe

    2002-07-01

    Le quatrième colloque Rayons X et Matière (RX 2001) s'est tenu à Strasbourg du 4 au 7 décembre 2001. Comme lors des colloques précédents (1995, 1997 et 1999) nous avons pu réunir de nombreux chercheurs, industriels et constructeurs concernés par la caractérisation des matériaux. Cette manifestation qui se déroule tous les deux ans a pour objectifs de rendre compte périodiquement des avancées faites dans le domaine des techniques X et plus particulièrement de l'ingénierie des surfaces. Cette année nous avons ajouté deux nouveaux thèmes : étude des nanomatériaux et techniques des microfaisceaux. André GUINIER était avec nous lors du premier colloque (colloque 1995, consacré à la commémoration du centenaire de la découverte des rayons X). Nous sommes attristés par son décès et nous lui dédions le Colloque RX 2001. Les premiers articles de cet ouvrage rappellent sa vie de scientifique et ses principaux travaux. En même temps que nous écrivons ces quelques lignes, nous nous préparons à lancer le colloque RX 2003. Ces colloques ont lieu grâce à la participation constante des chercheurs et l'engagement des constructeurs et distributeurs de matériels ; nous les en remercions vivement et nous leur donnons rendez-vous à Strasbourg, en décembre 2003.

  1. 24 Inch Reusable Solid Rocket Motor Test

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A scaled-down 24-inch version of the Space Shuttle's Reusable Solid Rocket Motor was successfully fired for 21 seconds at a Marshall Space Flight Center (MSFC) Test Stand. The motor was tested to ensure a replacement material called Lycocel would meet the criteria set by the Shuttle's Solid Motor Project Office. The current material is a heat-resistant, rayon-based, carbon-cloth phenolic used as an insulating material for the motor's nozzle. Lycocel, a brand name for Tencel, is a cousin to rayon and is an exceptionally strong fiber made of wood pulp produced by a special 'solvent-spirning' process using a nontoxic solvent. It will also be impregnated with a phenolic resin. This new material is expected to perform better under the high temperatures experienced during launch. The next step will be to test the material on a 48-inch solid rocket motor. The test, which replicates launch conditions, is part of Shuttle's ongoing verification of components, materials, and manufacturing processes required by MSFC, which oversees the Reusable Solid Rocket Motor project. Manufactured by the ATK Thiokol Propulsion Division in Promontory, California, the Reusable Solid Rocket Motor measures 126 feet (38.4 meters) long and 12 feet (3.6 meters) in diameter. It is the largest solid rocket motor ever flown and the first designed for reuse. During its two-minute burn at liftoff, each motor generates an average thrust of 2.6 million pounds (1.2 million kilograms).

  2. The Influence of Roentgen Radiation and Thermic Neutrons Upon Cereals and Corn; L'INFLUENCE DE L'IRRADIATION AVEC DES RAYONS X ET DES NEUTRONS THERMIQUES SUR LES GRAINES DE CEREALES ET DE MAIS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Priadcenco, Al.; Melacrinos, A.; Avramoaie, P.

    1959-10-31

    Seeds from several species of wheat, barley, oats, and corn of Rumanian origin were irradiated with different intensities of x radiation and thermal neutrons. The results showed that radiation inhibits the germination of the grains. The plants from the irradiated grains have a slower growth and development, a prolongment of the vegetative cycle, a pronounced sterility, and a greater sensitivity to diseases. The detailed results are tabulated. (J.S.R.)

  3. Swell Across the Continental Shelf

    DTIC Science & Technology

    2001-09-01

    Arlington, VA The views expressed in this thesis are those of the author and do not reflect the official policy or position of the Department of Defense ...le terme de source, tandis que les effets de la réfraction et du levage causés par les variations de profondeur aux échelles sous-maille sont...précisement pris en compte grâce aux rayons pré- calculés. Ainsi ce modèle peut être appliqué à de vastes zones côtières avec des maillages

  4. Evaluation of sprayed hypochlorous acid solutions for their virucidal activity against avian influenza virus through in vitro experiments

    PubMed Central

    HAKIM, Hakimullah; THAMMAKARN, Chanathip; SUGURO, Atsushi; ISHIDA, Yuki; KAWAMURA, Akinobu; TAMURA, Miho; SATOH, Keisuke; TSUJIMURA, Misato; HASEGAWA, Tomomi; TAKEHARA, Kazuaki

    2014-01-01

    Hypochlorous acid (HOCl) solutions were evaluated for their virucidal ability against a low pathogenic avian influenza virus (AIV), H7N1. HOCl solutions containing 50, 100 and 200 ppm chlorine (pH 6) or their sprayed solutions (harvested in dishes placed at 1 or 30 cm distance between the spray nozzle and dish) were mixed with the virus with or without organic materials (5% fetal bovine serum: FBS). Under plain diluent conditions (without FBS), harvested solutions of HOCl after spraying could decrease the AIV titer by more than 1,000 times, to an undetectable level (< 2.5 log10TCID50/ml) within 5 sec, with the exception of the 50 ppm solution harvested after spraying at the distance of 30 cm. Under the dirty conditions (in the presence of 5% FBS), they lost their virucidal activity. When HOCl solutions were sprayed directly on the virus on rayon sheets for 10 sec, the solutions of 100 and 200 ppm could inactivate AIV immediately after spraying, while 50 ppm solution required at least 3 min of contact time. In the indirect spray form, after 10 sec of spraying, the lids of the dishes were opened to expose the virus on rayon sheets to HOCl. In this form, the 200 ppm solution inactivated AIV within 10 min of contact, while 50 and 100 ppm could not inactivate it. These data suggest that HOCl can be used in spray form to inactivate AIV at the farm level. PMID:25421399

  5. Carbon disulfide exposure and neurotoxic sequelae among viscose rayon workers

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Aaserud, O.; Hommeren, O.J.; Tvedt, B.

    1990-01-01

    In Norway's only viscose rayon plant, carbon disulfide (CS2) concentrations in ambient air usually were between 30 and 50 mg/m3 during the first 23 years of production. From 1970/1971 until the factory was closed in 1982, corresponding values were 10-25 mg/m3. Through all of these years, high peak exposures of CS2 and H2S occurred. In 1986, 16 of the 24 men still at work in 1982 and with at least 10 years' experience in the spinning room agreed to participate in this study. Clinical neurological examination demonstrated abnormalities in 15; neuropsychological tests showed impairments of probable organic origin in 14.more » Thirteen had cerebral atrophy demonstrated by cerebral computed tomography (CT). Electromyography (EMG) was abnormal in six, neurography in 11. Regional cerebral blood flow measurements indicated flow asymmetries in eight, whereas Doppler investigation of the extracranial carotid and vertebral arteries, electroencephalography (EEG), and evoked response investigations were mostly normal. Based on these results and the exposure data, a diagnosis of CS2-induced encephalopathy was reached in eight workers; another six had an encephalopathy in which CS2 exposure was regarded as a partial cause. Correspondingly, seven had a neuropathy probably caused by CS2 exposure alone; in three others, CS2 was found to be the partial cause of a neuropathy. This indicates that long-term, relatively moderate exposure to CS2 in association with high peak exposures to CS2 and H2S involves a substantial risk of developing neurotoxic disease.« less

  6. Analyse de l'état mécanique et microstructural de films minces supraconducteurs YBa_2 Cu_3O_7 par diffraction des rayons X

    NASA Astrophysics Data System (ADS)

    Auzary, S.; Badawi, K. F.; Bimbault, L.; Rabier, J.; Gaboriaud, R. J.; Goudeau, Ph.

    1997-01-01

    Mechanical and microstructural analysis in a 100nm thin film is presented in this study. Using X-ray diffraction with a tensorial approach, we have determined stresses, strains, stress-free lattice parameters, microdistorsions and diffracting coherent domains size. Stress-free lattice parameters are higher than the bulk values. A high value of stresses is explained as a combination of coherent stresses, thermal stresses and intrinsic ones. Diffraction peaks line profiles analysis suggests grain boundaries presence as well as high lattice elastic microdistorsions. Cette étude présente une analyse de l'état mécanique et microstructurale dans un film mince de 100nm d'épaisseur d'YBCO déposé sur un substrat de MgO. En utilisant la diffraction des rayons X couplée à une approche tensorielle, nous avons déterminé les déformations, les contraintes, les paramètres libres de contraintes, les microdistorsions élastiques ainsi que la taille des domaines cohérents de diffraction. Les paramètres libres de contrainte sont supérieurs à ceux du massif. Une valeur élevée des contraintes est expliquée à partir des contraintes de cohérence, des contraintes thermiques et intrinsèques. L'analyse des profils des pics de diffraction suggère la présence de sous-joints et de distorsions élastiques élevées au niveau des mailles cristallographiques.

  7. Linkages between Snow Cover Seasonality, Terrain, and Land Surface Phenology in the Highland Pastures of Kyrgyzstan

    NASA Astrophysics Data System (ADS)

    Henebry, Geoffrey; Tomaszewska, Monika; Kelgenbaeva, Kamilya

    2017-04-01

    In the highlands of Kyrgyzstan, vertical transhumance is the foundation of montane agropastoralism. Terrain attributes, such as elevation, slope, and aspect, affect snow cover seasonality, which is a key influence on the timing of plant growth and forage availability. Our study areas include the highland pastures in Central Tien Shan mountains, specifically in the rayons of Naryn and At-Bashy in Naryn oblast, and Alay and Chong-Alay rayons in Osh oblast. To explore the linkages between snow cover seasonality and land surface phenology as modulated by terrain and variations in thermal time, we use 16 years (2001-2016) of Landsat surface reflectance data at 30 m resolution with MODIS land surface temperature and snow cover products at 1 km and 500 m resolution, respectively, and two digital elevation models, SRTM and ASTER GDEM. We model snow cover seasonality using frost degree-days and land surface phenology using growing degree-days as quadratic functions of thermal time: a convex quadratic (CxQ) model for land surface phenology and a concave quadratic (CvQ) model for snow cover seasonality. From the fitted parameter coefficients, we calculated phenometrics, including "peak height" and "thermal time to peak" for the CxQ models and "trough depth" and "thermal time to trough" for the CvQ models. We explore how these phenometrics change as a function of elevation and slope-aspect interactions and due to interannual variability. Further, we examine how snow cover duration and timing affects the subsequent peak height and thermal time to peak in wetter, drier, and normal years.

  8. Preparation of silicon carbide fibers

    DOEpatents

    Wei, G.C.

    1983-10-12

    Silicon carbide fibers suitable for use in the fabrication of dense, high-strength, high-toughness SiC composites or as thermal insulating materials in oxidizing environments are fabricated by a new, simplified method wherein a mixture of short-length rayon fibers and colloidal silica is homogenized in a water slurry. Water is removed from the mixture by drying in air at 120/sup 0/C and the fibers are carbonized by (pyrolysis) heating the mixture to 800 to 1000/sup 0/C in argon. The mixture is subsequently reacted at 1550 to 1900/sup 0/C in argon to yield pure ..beta..-SiC fibers.

  9. New electron beam facility for R&D and production at acsion industries

    NASA Astrophysics Data System (ADS)

    Lopata, V. J.; Barnard, J. W.; Saunders, C. B.; Stepanik, T. M.

    2003-08-01

    Since its incorporation in 1998, Acsion Industries Inc. has been working with clients to develop industrial uses of electron processing for improving products and manufacturing processes. Acsion has promoted this technology for sterilizing medical devices and pharmaceuticals, for treating wood pulp in the viscose/rayon process, for reducing pathogens in food and animal feed, and for curing advanced composites for the aerospace industry. As a result of significant developments in its composite curing programs, Acsion has recently made major modifications to its facility to increase its production and R&D capabilities. These modifications are described in this paper.

  10. Fluid Absorption and Release of Nonwovens and their Response to Compression

    NASA Astrophysics Data System (ADS)

    Bateny, Fatemeh

    Fluid handling is a key property in one of the major nonwoven applications in absorbent product such as wipes, hygiene products, and baby diapers. These products are subjected to various levels of compression in real-use. The aim of this study was to investigate the liquid absorption and release properties of nonwovens to establish the absorption structure-property relationship at various compression levels. A comprehensive methodology, considering various flow directions, was employed to establish the relationship by decoupling the effect of structural parameters and material properties in two phases of this study respectively. In the first phase, the mechanism of absorption by pore structure was investigated through considering various fiber cross-sectional size and shape, as well as heterogeneous layered structures having a pore size reduction and expansion. In the second phase, the mechanism of absorption by fiber and consequent swelling was evaluated in view of fluid diffusion into the rayon fibers in samples having different percentages of PET fiber (non-absorbent) and rayon fiber (absorbent). The analysis of absorption and release properties through the entire dissertation was based on the pore characteristics of the nonwovens by measuring the average pore sizes, pore size distribution, and solidity. The investigation revealed that the absorption and release properties of nonwovens are governed by their pore characteristics. In homogeneous non-layered nonwoven fabrics, maximum absorption is mainly governed by the available pore volume. Absorbency rate is determined according to pore size and the maximum rate of absorption is achieved at a specific range of pore sizes. This indicates that an in-depth understanding of the absorption and release properties brings about valuable information for the absorbent product engineering.

  11. Utility of snout wipe samples for influenza A virus surveillance in exhibition swine populations

    PubMed Central

    Edwards, Jody L; Nelson, Sarah W; Workman, Jeffrey D; Slemons, Richard D; Szablewski, Christine M; Nolting, Jacqueline M; Bowman, Andrew S

    2014-01-01

    Background Sporadic influenza A virus (IAV) outbreaks in humans and swine have resulted from commingling of large numbers of people and pigs at agricultural fairs in the United States. Current antemortem IAV surveillance strategies in swine require collecting nasal swabs, which entails restraining pigs with snares. Restraint is labor-intensive for samplers, stressful for pigs, and displeasing to onlookers because pigs often resist and vocalize. Objective To evaluate the utility of snout wipes in exhibition swine as a method to make IAV surveillance efforts less intrusive, less labor-intensive, and more widely accepted among pig owners and exhibition officials. Methods Three materials (rayon/polyester gauze, cotton gauze, and Swiffer® Sweeper dry cloths) were inoculated with IAV, and viral recoveries from these materials were quantified using qRT-PCR and TCID50 assays. In a field trial, paired cotton gauze snout wipes and gold standard polyester-tipped nasal swabs were collected from 553 pigs representing 29 agricultural fairs and the qualitative results of rRT-PCR and viral isolation were compared. Results and Conclusions Viral recoveries from potential snout wipe materials ranged from 0·26 to 1·59 log10 TCID50/ml less than that of the positive control in which no substrate was included; rayon/polyester gauze performed significantly worse than the other materials. In the field, snout wipes and nasal swabs had high levels of agreement for both rRT-PCR detection and virus isolation. Although further investigation and refinement of the sampling method is needed, results indicate that snout wipes will facilitate convenient and undisruptive IAV surveillance in pigs at agricultural fairs. PMID:25043408

  12. Carbon Disulfide (CS2) Interference in Glucose Metabolism from Unconventional Oil and Gas Extraction and Processing Emissions.

    PubMed

    Rich, Alisa L; Patel, Jay T; Al-Angari, Samiah S

    2016-01-01

    Carbon disulfide (CS2) has been historically associated with the manufacturing of rayon, cellophane, and carbon tetrachloride production. This study is one of the first to identify elevated atmospheric levels of CS2 above national background levels and its mechanisms to dysregulate normal glucose metabolism. Interference in glucose metabolism can indirectly cause other complications (diabetes, neurodegenerative disease, and retinopathy), which may be preventable if proper precautions are taken. Rich et al found CS2 and 12 associated sulfide compounds present in the atmosphere in residential areas where unconventional shale oil and gas extraction and processing operations were occurring. Ambient atmospheric concentrations of CS2 ranged from 0.7 parts per billion by volume (ppbv) to 103 ppbv over a continuous 24-hour monitoring period. One-hour ambient atmospheric concentrations ranged from 3.4 ppbv to 504.6 ppbv. Using the U.S. Environmental Protection Agency Urban Air Toxic Monitoring Program study as a baseline comparison for atmospheric CS2 concentrations found in this study, it was determined that CS2 atmospheric levels were consistently elevated in areas where unconventional oil and gas extraction and processing occurred. The mechanisms by which CS2 interferes in normal glucose metabolism by dysregulation of the tryptophan metabolism pathway are presented in this study. The literature review found an increased potential for alteration of normal glucose metabolism in viscose rayon occupational workers exposed to CS2. Occupational workers in the energy extraction industry exposed to CS2 and other sulfide compounds may have an increased potential for glucose metabolism interference, which has been an indicator for diabetogenic effect and other related health impacts. The recommendation of this study is for implementation of regular monitoring of blood glucose levels in CS2-exposed populations as a preventative health measure.

  13. Methode des Rayons avec Calcul d’Intensite Appliquee a la Propagation Anormale (Method of Ray Intensity Calculation as Applied to Anomalous Propagation),

    DTIC Science & Technology

    1986-06-01

    D’INTENSITE 0 APPLIQUEE A LA PROPAGATION "ANORNALE" par D. Dion DEFENCE RESEARCH ESTABLISHMENT CENTRE DE RECHERCHES POUR LA DEFENSE VALCARTI ER 6- Tel: (418...faqon ils sont reli~s aux conditions atmosph~riques. Les ph~no- manes les plus importants A signaler sont les conduits et les "trous radio". En effet...6tant tr~s fr~quents en mer, 11 est d’int&rt pour la marine de rechercher des m~thodes simples permettant de les caract~riser. Des 6quations d’int

  14. Carbon felt and carbon fiber - A techno-economic assessment of felt electrodes for redox flow battery applications

    NASA Astrophysics Data System (ADS)

    Minke, Christine; Kunz, Ulrich; Turek, Thomas

    2017-02-01

    Carbon felt electrodes belong to the key components of redox flow batteries. The purpose of this techno-economic assessment is to uncover the production costs of PAN- and rayon-based carbon felt electrodes. Raw material costs, energy demand and the impact of processability of fiber and felt are considered. This innovative, interdisciplinary approach combines deep insights into technical, ecologic and economic aspects of carbon felt and carbon fiber production. Main results of the calculation model are mass balances, cumulative energy demands (CED) and the production costs of conventional and biogenic carbon felts supplemented by market assessments considering textile and carbon fibers.

  15. The Development of Laminated Armor

    DTIC Science & Technology

    1948-09-27

    U.S. Army Ramie Sea Island Mills, Inc. Ramie-Rayon Sea Island Mills, Ilc. Inconel Fabric (006R260R13) Metal Tex Co. -4- Inconel Fabric (00R21OMl6...Plies .02 U.D. Glass Mat 3111-44 4 Plies .02 IT.D. Glass Mat f 110 90 100 1 Ply Nylon Dusk(13 Oz.) I Ply 00R260R13 2-l/4# Inconel 2 Puiem Nylon Duck(13 Oz...13 Oz.) 1 Ply O07R210M16 2-1/4# Inconel 2 Pl•es Nylon Duck(13 Oz.) I Ply 007R210MI( ?-1/4# Inconel 1 Ply Nylon Duck(13 Oz.) 4 Plies .02 U.D. Mlass Mat

  16. A review on the cords & plies reinforcement of elastomeric polymer matrix

    NASA Astrophysics Data System (ADS)

    Mahmood, S. S.; Husin, H.; Mat-Shayuti, M. S.; Hassan, Z.

    2016-06-01

    Steel, polyester, nylon and rayon are the main materials of cords & plies that have been reinforced in the natural rubber to produce quality tyres but there is few research reported on cord and plies reinforcement in silicone rubber. Taking the innovation of tyres as inspiration, this review's first objective is to compile the comprehensive studies about the cords & plies reinforcement in elastomeric polymer matrix. The second objective is to gather information about silicone rubber that has a high potential as a matrix phase for cords and plies reinforcement. All the tests and findings are gathered and compiled in sections namely processing preparation, curing, physical and mechanical properties, and adhesion between cords-polymer.

  17. Control of Precision Grip Force in Lifting and Holding of Low-Mass Objects

    PubMed Central

    Kimura, Daisuke; Kadota, Koji; Ito, Taro

    2015-01-01

    Few studies have investigated the control of grip force when manipulating an object with an extremely small mass using a precision grip, although some related information has been provided by studies conducted in an unusual microgravity environment. Grip-load force coordination was examined while healthy adults (N = 17) held a moveable instrumented apparatus with its mass changed between 6 g and 200 g in 14 steps, with its grip surface set as either sandpaper or rayon. Additional measurements of grip-force-dependent finger-surface contact area and finger skin indentation, as well as a test of weight discrimination, were also performed. For each surface condition, the static grip force was modulated in parallel with load force while holding the object of a mass above 30 g. For objects with mass smaller than 30 g, on the other hand, the parallel relationship was changed, resulting in a progressive increase in grip-to-load force (GF/LF) ratio. The rayon had a higher GF/LF force ratio across all mass levels. The proportion of safety margin in the static grip force and normalized moment-to-moment variability of the static grip force were also elevated towards the lower end of the object mass for both surfaces. These findings indicate that the strategy of grip force control for holding objects with an extremely small mass differs from that with a mass above 30 g. The data for the contact area, skin indentation, and weight discrimination suggest that a decreased level of cutaneous feedback signals from the finger pads could have played some role in a cost function in efficient grip force control with low-mass objects. The elevated grip force variability associated with signal-dependent and internal noises, and anticipated inertial force on the held object due to acceleration of the arm and hand, could also have contributed to the cost function. PMID:26376484

  18. Upper Stage Engine Composite Nozzle Extensions

    NASA Technical Reports Server (NTRS)

    Valentine, Peter G.; Allen, Lee R.; Gradl, Paul R.; Greene, Sandra E.; Sullivan, Brian J.; Weller, Leslie J.; Koenig, John R.; Cuneo, Jacques C.; Thompson, James; Brown, Aaron; hide

    2015-01-01

    Carbon-carbon (C-C) composite nozzle extensions are of interest for use on a variety of launch vehicle upper stage engines and in-space propulsion systems. The C-C nozzle extension technology and test capabilities being developed are intended to support National Aeronautics and Space Administration (NASA) and United States Air Force (USAF) requirements, as well as broader industry needs. Recent and on-going efforts at the Marshall Space Flight Center (MSFC) are aimed at both (a) further developing the technology and databases for nozzle extensions fabricated from specific CC materials, and (b) developing and demonstrating low-cost capabilities for testing composite nozzle extensions. At present, materials development work is concentrating on developing a database for lyocell-based C-C that can be used for upper stage engine nozzle extension design, modeling, and analysis efforts. Lyocell-based C-C behaves in a manner similar to rayon-based CC, but does not have the environmental issues associated with the use of rayon. Future work will also further investigate technology and database gaps and needs for more-established polyacrylonitrile- (PAN-) based C-C's. As a low-cost means of being able to rapidly test and screen nozzle extension materials and structures, MSFC has recently established and demonstrated a test rig at MSFC's Test Stand (TS) 115 for testing subscale nozzle extensions with 3.5-inch inside diameters at the attachment plane. Test durations of up to 120 seconds have been demonstrated using oxygen/hydrogen propellants. Other propellant combinations, including the use of hydrocarbon fuels, can be used if desired. Another test capability being developed will allow the testing of larger nozzle extensions (13.5- inch inside diameters at the attachment plane) in environments more similar to those of actual oxygen/hydrogen upper stage engines. Two C-C nozzle extensions (one lyocell-based, one PAN-based) have been fabricated for testing with the larger-scale facility.

  19. On the Identification of Rayon/Viscose as a Major Fraction of Microplastics in the Marine Environment: Discrimination between Natural and Manmade Cellulosic Fibers Using Fourier Transform Infrared Spectroscopy

    PubMed Central

    Comnea-Stancu, Ionela Raluca; Wieland, Karin; Ramer, Georg; Schwaighofer, Andreas

    2016-01-01

    This work was sparked by the reported identification of man-made cellulosic fibers (rayon/viscose) in the marine environment as a major fraction of plastic litter by Fourier transform infrared (FT-IR) transmission spectroscopy and library search. To assess the plausibility of such findings, both natural and man-made fibers were examined using FT-IR spectroscopy. Spectra acquired by transmission microscopy, attenuated total reflection (ATR) microscopy, and ATR spectroscopy were compared. Library search was employed and results show significant differences in the identification rate depending on the acquisition method of the spectra. Careful selection of search parameters and the choice of spectra acquisition method were found to be essential for optimization of the library search results. When using transmission spectra of fibers and ATR libraries it was not possible to differentiate between man-made and natural fibers. Successful differentiation of natural and man-made cellulosic fibers has been achieved for FT-IR spectra acquired by ATR microscopy and ATR spectroscopy, and application of ATR libraries. As an alternative, chemometric methods such as unsupervised hierarchical cluster analysis, principal component analysis, and partial least squares-discriminant analysis were employed to facilitate identification based on intrinsic relationships of sample spectra and successful discrimination of the fiber type could be achieved. Differences in the ATR spectra depending on the internal reflection element (Ge versus diamond) were observed as expected; however, these did not impair correct classification by chemometric analysis. Moreover, the effects of different levels of humidity on the IR spectra of natural and man-made fibers were investigated, too. It has been found that drying and re-humidification leads to intensity changes of absorption bands of the carbohydrate backbone, but does not impair the identification of the fiber type by library search or cluster analysis. PMID:27650982

  20. An Update to a Conformal Ablative Thermal Protection System for Planetary and Human Exploration Missions

    NASA Technical Reports Server (NTRS)

    Beck, R.; Arnold, J.; Gasch, M.; Stackpoole, M.; Venkatapathy, E.

    2014-01-01

    As described at IPPW-10, in FY12, the CA-TPS element focused on establishing materials requirements based on MSL-type and COTS Low Earth orbit (LEO) conditions (q 250 Wcm2) to develop and deliver a conformal ablative TPS. This involved down selecting, manufacturing and testing two of the best candidate materials, demonstrating uniform infiltration of resins into baseline 2-cm thick carbon felt, selecting a primary conformal material formulation based on novel arc jet and basic material properties testing, developing and demonstrating instrumentation for felt-based materials and, based on the data, developing a low fidelity material response model so that the conformal ablator TPS thickness for missions could be established. In addition, the project began to develop Industry Partnerships. Since the nominal thickness of baseline carbon felts was only 2-cm, a partnership with a rayon felt developer was made in order to upgrade equipment, establish the processes required and attempt to manufacture 10-cm thick white goods. A partnership with a processing house was made to develop the methodology to carbonize large pieces of the white goods into 7.5-cm thick carbon felt. In FY13, more advanced testing and modeling of the down selected conformal material was performed. Material thermal properties tests and structural properties tests were performed. The first 3 and 4-point bend tests were performed on the conformal ablator as well as PICA for comparison and the conformal ablator had outstanding behavior compared to PICA. Arc jet testing was performed with instrumented samples of both the conformal ablator and standard PICA at heating rates ranging from 40 to 400 Wcm2 and shear as high as 600 Pa. The results from these tests showed a remarkable improvement in the thermal penetration through the conformal ablator when compared to PICAs response. The data from these tests were used to develop a mid-fidelity thermal response model. Additional arc jet testing in the same conditions on various seam designs were very successful in showing that the material could be joined with a minimum of adhesive and required no complicated gap and gap filler design for installation. In addition, the partnership with industry to manufacture thicker rayon felt was very successful. The vendor made a 2-m wide by 30-m long sample of 10-cm thick rayon felt. When carbonized, the resulting thickness was over 7.5-cm thick, nearly 4 times the thickest off-the-shelf carbon felt. In FY14, the project has initiated a partnership with another vendor to begin the scale-up manufacturing effort. This year, the vendor will duplicate the process and manufacture at the current scale for comparison with NASA-processed materials. Properties testing and arc jet testing will be performed on the vendor-processed materials. Planning for manufacturing large, 1-m x 1-m, panels will begin as well. In FY15, the vendor will then manufacture large panels and the project will build a 2-m x 2-m Manufacturing Demonstration Unit (MDU).

  1. Conformal Ablative Thermal Protection System for Planetary and Human Exploration Missions: An Update of the Technology Maturation Effort

    NASA Technical Reports Server (NTRS)

    Beck, R.; Arnold, J.; Gasch, M.; Stackpoole, M.; Venkatapathy, E.

    2014-01-01

    This presentation will update the community on the development of conformal ablative TPS. As described at IPPW-10, in FY12, the CA-TPS element focused on establishing materials requirements based on MSL-type and COTS Low Earth orbit (LEO) conditions (q 250 Wcm2) to develop and deliver a conformal ablative TPS. This involved downselecting, manufacturing and testing two of the best candidate materials, demonstrating uniform infiltration of resins into baseline 2-cm thick carbon felt, selecting a primary conformal material formulation based on novel arc jet and basic material properties testing, developing and demonstrating instrumentation for felt-based materials and, based on the data, developing a low fidelity material response model so that the conformal ablator TPS thickness for missions could be established. In addition, the project began to develop Industry Partnerships. Since the nominal thickness of baseline carbon felts was only 2-cm, a partnership with a rayon felt developer was made in order to upgrade equipment, establish the processes required and attempt to manufacture 10-cm thick white goods. A partnership with a processing house was made to develop the methodology to carbonize large pieces of the white goods into 7.5-cm thick carbon felt.In FY13, more advanced testing and modeling of the downselected conformal material was performed. Material thermal properties tests and structural properties tests were performed. The first 3 and 4-point bend tests were performed on the conformal ablator as well as PICA for comparison and the conformal ablator had outstanding behavior compared to PICA. Arc jet testing was performed with instrumented samples of both the conformal ablator and standard PICA at heating rates ranging from 40 to 400 Wcm2 and shear as high as 600 Pa. The results from these tests showed a remarkable improvement in the thermal penetration through the conformal ablator when compared to PICAs response. The data from these tests were used to develop a mid-fidelity thermal response model. Additional arc jet testing in the same conditions on various seam designs were very successful in showing that the material could be joined with a minimum of adhesive and required no complicated gap and gap filler design for installation. In addition, the partnership with industry to manufacture thicker rayon felt was very successful. The vendor made a 2-m wide by 30-m long sample of 10-cm thick rayon felt. When carbonized, the resulting thickness was over 7.5-cm thick, nearly 4 times the thickest off-the-shelf carbon felt. In FY14, the project has initiated a partnership with another vendor to begin the scale-up manufacturing effort. This year, the vendor will duplicate the process and manufacture at the current scale for comparison with NASA-processed materials. Properties testing and arc jet testing will be performed on the vendor-processed materials. Planning for manufacturing large, 1-m x 1-m, panels will begin as well. In FY15, the vendor will then manufacture large panels and the project will build a 2-m x 2-m Manufacturing Demonstration Unit (MDU).

  2. [Comparative carcinogenic properties of basalt fiber and chrysotile-asbestos].

    PubMed

    Nikitina, O V; Kogan, F M; Vanchugova, N N; Frash, V N

    1989-01-01

    In order to eliminate asbestos adverse effect on workers' health it was necessary to use mineral rayon, primarily basalt fibre, instead of asbestos. During a chronic experiment on animals the oncogenicity of 2 kinds of basalt fibre was studied compared to chrysotile asbestos. The dust dose of 25 mg was twice administered by intraperitonial route. All types of dust induced the onset of intraperitonial mesotheliomas but neoplasm rates were significantly lower in the groups exposed to basalt fibre. There was no credible data on the differences between the groups exposed to various types of basalt fibre. Since the latter produced some oncogenic effect, it was necessary to develop a complex of antidust measures, fully corresponding to the measures adopted for carcinogenic dusts.

  3. Electron-processing technology: A promising application for the viscose industry

    NASA Astrophysics Data System (ADS)

    Stepanik, T. M.; Rajagopal, S.; Ewing, D.; Whitehouse, R.

    1998-06-01

    In marketing its IMPELA ® line of high power, high-throughput industrial accelerators, Atomic Energy of Canada Limited (AECL) is working with viscose (rayon) companies world-wide to integrate electron-processing technology as part of the viscose manufacturing process. The viscose industry converts cellulose wood pulp into products such as staple fiber, filament, cord, film, packaging, and non-edible sausage casings. This multibillion dollar industry is currently suffering from high production costs, and is facing increasingly stringent environmental regulations. The use of electron-treated pulp can significantly lower production costs and can provide equally significant environmental benefits. This paper describes our current understanding of the benefits of using electron-treated pulp in this process, and AECL's efforts in developing this technology.

  4. Prospects for using carbon-carbon composites for EMI shielding

    NASA Technical Reports Server (NTRS)

    Gaier, James R.

    1990-01-01

    Since pyrolyzed carbon has a higher electrical conductivity than most polymers, carbon-carbon composites would be expected to have higher electromagnetic interference (EMI) shielding ability than polymeric resin composites. A rule of mixtures model of composite conductivity was used to calculate the effect on EMI shielding of substituting a pyrolyzed carbon matrix for a polymeric matrix. It was found that the improvements were small, no more than about 2 percent for the lowest conductivity fibers (ex-rayon) and less than 0.2 percent for the highest conductivity fibers (vapor grown carbon fibers). The structure of the rule of mixtures is such that the matrix conductivity would only be important in those cases where it is much higher than the fiber conductivity, as in metal matrix composites.

  5. Method for production of ceramic oxide and carbide bodies by polymer inclusion and decomposition

    DOEpatents

    Quinby, Thomas C.

    1985-01-01

    A method for the preparation of thin, free-standing metal oxide films which are useful as nuclear accelerator target materials. Cations of any metal except those of Group IA and precious metals, such as, U, Zr, Nd, Ce, Th, pr or Cr, are absorbed on a thin film of polymeric material, such as, carboxymethylcellulose, viscose rayon or cellophane. The cation impregnated polymeric material is dried. Then the impregnated film is heated in an inert atmosphere to form a carbonized membrane. The carbonized membrane is oxidized to yield a thin, self-supporting, metal oxide membrane. Or, the membrane can be heated in an inert atmosphere to yield a thin, self-supporting, metal carbide-containing membrane.

  6. Method for production of ceramic oxide and carbide bodies by polymer inclusion and decomposition

    DOEpatents

    Quinby, T.C.

    1984-08-30

    A method for the preparation of thin, free-standing metal oxide films which are useful as nuclear accelerator target materials is described. Cations of any metal except those of Group IA and precious metals, such as, U, Zr, Nd, Ce, Th, Pr or Cr, are absorbed on a thin film of polymeric material, such as carboxymethylcellulose, viscose rayon or cellophane. The cation impregnated polymeric material is dried. Then the impregnated film is heated in an inert atmosphere to form a carbonized membrane. The carbonized membrane is oxidized to yield a thin, self-supporting, metal oxide membrane. Or, the membrane can be heated in an inert atmosphere to yield a thin, self-supporting, metal carbide-containing membrane.

  7. Carbide coated fibers in graphite-aluminum composites

    NASA Technical Reports Server (NTRS)

    Imprescia, R. J.; Levinson, L. S.; Reiswig, R. D.; Wallace, T. C.; Williams, J. M.

    1975-01-01

    The study of protective-coupling layers of refractory metal carbides on the graphite fibers prior to their incorporation into composites is presented. Such layers should be directly wettable by liquid aluminum and should act as diffusion barriers to prevent the formation of aluminum carbide. Chemical vapor deposition was used to uniformly deposit thin, smooth, continuous coats of ZrC on the carbon fibers of tows derived from both rayon and polyacrylonitrile. A wet chemical coating of the fibers, followed by high-temperature treatment, was used, and showed promise as an alternative coating method. Experiments were performed to demonstrate the ability of aluminum alloys to wet carbide surfaces. Titanium carbide, zirconium carbide and carbide-coated graphite surfaces were successfully wetted. Results indicate that initial attempts to wet surfaces of ZrC-coated carbon fibers appear successful.

  8. Carbon disulfide exposure estimate and prevalence of chronic diseases after carbon disulfide poisoning-related occupational diseases.

    PubMed

    Chung, Hweemin; Youn, Kanwoo; Kim, Kyuyeon; Park, Kyunggeun

    2017-01-01

    In Korea, Carbon disulfide (CS 2 ) toxicity was an important social problem from the late 1980s to the early 1990s but there have been few large-scale studies examining the prevalence of diseases after CS 2 exposure discontinuance. So we investigated past working exposure to CS 2 characteristics from surviving ex-workers of a rayon manufacturing plant including cumulative CS 2 exposure index. Furthermore, we studied the prevalence of their chronic diseases recently after many years. We interviewed 633 ex-workers identified as CS 2 poisoning-related occupational diseases to determine demographic and occupational characteristics and reviewed their medical records. The work environment measurement data from 1992 was used as a reference. Based on the interviews and foreign measurement documents, weights were assigned to the reference concentrations followed by calculation of individual exposure index, the sum of the portion of each time period multiplied by the concentrations of CS 2 during that period. The cumulative exposure index was 128.2 ppm on average. Workers from the spinning, electrical equipment repair, and motor repair departments were exposed to high concentrations of ≥10 ppm. Workers from the maintenance of the ejector, manufacturing of CS 2, post-process, refining, maintenance and manufacturing of viscose departments were exposed to low concentrations below 10 ppm. The prevalence for hypertension, coronary artery disease, cerebrovascular disease, diabetes, arrhythmia, psychoneurotic disorder, disorders of the nervous system and sensory organ were 69.2%, 13.9%, 24.8%, 24.5%, 1.3%, 65.7%, 72.4% respectively. We estimated the individual cumulative CS 2 exposure based on interviews and foreign measurement documents, and work environment measurement data. Comparing the work environment measurement data from 1992, these values were similar to them. After identified as CS 2 poisoning, there are subjects over 70 years of average age with disorders of the nervous system and sensory organs, hypertension, psychoneurotic disorder, cerebrovascular disease, diabetes, coronary artery disease, and arrhythmia. Because among ex-workers of the rayon manufacturing plant, only 633 survivors recognized as CS 2 poisoning were studied, the others not identified as CS 2 poisoning should also be investigated in the future.

  9. Self-Decontaminating Fibrous Materials Reactive toward Chemical Threats.

    PubMed

    Bromberg, Lev; Su, Xiao; Martis, Vladimir; Zhang, Yunfei; Hatton, T Alan

    2016-07-13

    Polymers that possess highly nucleophilic pyrrolidinopyridine (Pyr) and primary amino (vinylamine, VAm) groups were prepared by free-radical copolymerization of N,N-diallylpyridin-4-amine (DAAP) and N-vinylformamide (NVF) followed by acidic hydrolysis of NVF into VAm. The resulting poly(DAAP-co-VAm-co-NVF) copolymers were water-soluble and reacted with water-dispersible polyurethane possessing a high content of unreacted isocyanate groups. Spray-coating of the nylon-cotton (NYCO), rayon, and poly(p-phenylene terephthalamide) (Kevlar 119) fibers pretreated with phosphoric acid resulted in covalent bonding of the polyurethane with the hydroxyl groups on the fiber surface. A second spray-coating of aqueous solutions of poly(DAAP-co-VAm-co-NVF) on the polyurethane-coated fiber enabled formation of urea linkages between unreacted isocyanate groups of the polyurethane layer and the amino groups of poly(DAAP-co-VAm-co-NVF). Fibers with poly(DAAP-co-VAm-co-NVF) attached were compared with fibers modified by adsorption of water-insoluble poly(butadiene-co-pyrrolidinopyridine) (polyBPP) in terms of the stability against polymer leaching in aqueous washing applications. While the fibers modified by attachment of poly(DAAP-co-VAm-co-NVF) exhibited negligible polymer leaching, over 65% of adsorbed polyBPP detached and leached from the fibers within 7 days. Rayon fibers modified by poly(DAAP-co-VAm-co-NVF) were tested for sorption of dimethyl methylphosphonate (DMMP) in the presence of moisture using dynamic vapor sorption technique. Capability of the fibers modified with poly(DAAP-co-VAm-co-NVF) to facilitate hydrolysis of the sorbed DMMP in the presence of moisture was uncovered. The self-decontaminating property of the modified fibers against chemical threats was tested using a CWA simulant diisopropylfluorophosphate (DFP) in aqueous media at pH 8.7. Fibers modified with poly(DAAP-co-VAm-co-NVF) facilitated hydrolysis of DFP with the half-lives up to an order of magnitude shorter than that of the unmodified fibers. The presented polymers and method of multilayer coating can lead to a development of self-decontaminating textiles and other materials.

  10. Electron treatment of wood pulp for the viscose process

    NASA Astrophysics Data System (ADS)

    Stepanik, T. M.; Ewing, D. E.; Whitehouse, R.

    2000-03-01

    Electron processing is currently being evaluated by several viscose producers for integration into their process. The viscose industry converts dissolving wood pulp into products such as staple fibre, filament, cord, film, packaging, and non-edible sausage casings. These materials are used in the clothing, drapery, hygiene, automobile, food, and packaging industries. Viscose producers are facing increasingly high production costs and stringent environmental regulations that have forced some plants to close. Electron treatment of wood pulp can significantly reduce the amounts of chemicals used for producing viscose and the production of hazardous pollutants. Acsion Industries has worked with companies worldwide to demonstrate the benefits of using electron treated pulp for producing viscose (rayon). This paper describes the viscose process, the benefits of using electron treatment in the viscose process, and Acsion's efforts in developing this technology.

  11. Carbon nano structures: Production and characterization

    NASA Astrophysics Data System (ADS)

    Beig Agha, Rosa

    L'objectif de ce memoire est de preparer et de caracteriser des nanostructures de carbone (CNS -- Carbon Nanostructures, en licence a l'Institut de recherche sur l'hydrogene, Quebec, Canada), un carbone avec un plus grand degre de graphitisation et une meilleure porosite. Le Chapitre 1 est une description generale des PEMFCs (PEMFC -- Polymer Electrolyte Membrane Fuel Cell) et plus particulierement des CNS comme support de catalyseurs, leur synthese et purification. Le Chapitre 2 decrit plus en details la methode de synthese et la purification des CNS, la theorie de formation des nanostructures et les differentes techniques de caracterisation que nous avons utilises telles que la diffraction aux rayons-X (XRD -- X-ray diffraction), la microscopie electronique a transmission (TEM -- transmission electron microscope ), la spectroscopie Raman, les isothermes d'adsorption d'azote a 77 K (analyse BET, t-plot, DFT), l'intrusion au mercure, et l'analyse thermogravimetrique (TGA -- thermogravimetric analysis). Le Chapitre 3 presente les resultats obtenus a chaque etape de la synthese des CNS et avec des echantillons produits a l'aide d'un broyeur de type SPEXRTM (SPEX/CertiPrep 8000D) et d'un broyeur de type planetaire (Fritsch Pulverisette 5). La difference essentielle entre ces deux types de broyeur est la facon avec laquelle les materiaux sont broyes. Le broyeur de type SPEX secoue le creuset contenant les materiaux et des billes d'acier selon 3 axes produisant ainsi des impacts de tres grande energie. Le broyeur planetaire quant a lui fait tourner et deplace le creuset contenant les materiaux et des billes d'acier selon 2 axes (plan). Les materiaux sont donc broyes differemment et l'objectif est de voir si les CNS produits ont les memes structures et proprietes. Lors de nos travaux nous avons ete confrontes a un probleme majeur. Nous n'arrivions pas a reproduire les CNS dont la methode de synthese a originellement ete developpee dans les laboratoires de l'Institut de recherche sur l'hydrogene (IRH). Nos echantillons presentaient toujours une grande quantite de carbure de fer au detriment de la formation de nanostructures de carbone. Apres plusieurs mois de recherche nous avons constate que les metaux de base, soit le fer et le cobalt, etaient contamines. Neanmoins, ces recherches nous ont enseigne beaucoup et les resultats sont presentes aux Appendices I a III. Le carbone de depart est du charbon active commercial (CNS201) qui a ete prealablement chauffe a 1,000°C sous vide pendant 90 minutes pour se debarrasser de toute humidite et autres impuretes. En premiere etape, dans un creuset d'acier durci du CNS201 pretraite fut melange a une certaine quantite de Fe et de Co (99.9 % purs). Des proportions typiques sont 50 pd. %, 44 pd. %, et 6 pd. % pour le C, le Fe, et le Co respectivement. Pour les echantillons prepares avec le broyeur SPEX, trois a six billes en acier durci furent utilisees pour le broyage, de masse relative echantillon/poudre de 35 a 1. Pour les echantillons prepares avec le broyeur planetaire, trente-six billes en acier durci furent utilisees pour le broyage, de masse relative echantillon/poudre de 10 a 1. L'hydrogene fut alors introduit dans le creuset pour les deux types de broyeur a une pression de 1.4 MPa, et l'echantillon fut broye pendant 12 h pour le SPEX et 24 h pour le planetaire. Le broyeur SPEX a un rendement de transfert d'energie mecanique plus grand qu'un broyeur planetaire, mais il a le desavantage de contaminer davantage l'echantillon en Fe par attrition. Cependant, ceci peut etre neglige vu que le Fe etait un des catalyseurs metalliques ajoutes au creuset. En deuxieme etape, l'echantillon broye est transfere sous gaz inerte (argon) dans un tube en quartz, qui est alors chauffe a 700°C pendant 90 minutes. Des mesures de patrons de diffraction a rayons-X sur poudre furent faites pour caracteriser les changements structurels des CNS lors des etapes de synthese. Ces mesures furent prises avec un diffractometre Bruker D8 FOCUS utilisant le rayonnement Cu Ka (lambda = 1.54054 A) et une geometrie Theta/2Theta. La Figure 3.1 montre le patron de diffraction de rayon-X du charbon active utilise comme precurseur pour produire les CNS. Le charbon active est prechauffe a haute temperature (1,000°C) pendant 1 h pour enlever l'humidite. La Figure 3.2 montre les patrons de diffraction de rayons-X des echantillons SPEX et planetaire apres broyage de 12 h et 24 h, respectivement. Les structures de charbon ne sont pas encore bien definies, mais un pic a 2theta ≈ 20°-30° correspond aux petites cristallites a caractere turbostatique et un pic correspondant au fer et au carbure de fer apparait a 2theta ≈ 45°. (Abstract shortened by UMI.)

  12. ÉTUDE de la Capture ÉLECTRONIQUE dans la DÉSINTÉGRATION du Nuclide 23Na

    NASA Astrophysics Data System (ADS)

    Charpak, G.

    L'étude de 22Na est faite avec un compteur Geiger 4π. On met en évidence l'émission d'un rayonnement de très basse énergle, indépendant des rayons β+, complètement absorbé dans un film de quelques microgrammes par centimètre carré d'aluminium on de matière plastique LC 600 et attribué aux électrons Auger d'énergie maximum 0,85 keV, qui suivent la capture électronique. En raison du très faible parcours de ces électrons , nous sommes amené à discuter particulièrement une méthode simple de préparation de sources radloactives minces et uniformes. Nous obtenons la valeta du rapport [ Capture Λ/Emission β+ = (6,5±0,9) pour 100.

  13. Improved ablative materials for the ASRM nozzle

    NASA Technical Reports Server (NTRS)

    Canfield, A.; Clinton, R. G.; Armour, W.; Koenig, J.

    1992-01-01

    Rayon precursor carbon-cloth phenolic was developed more than 30 years ago and is used in most nozzles today including the Poseidon, Trident, Peacekeeper, Small ICBM, Space Shuttle, and numerous tactical and space systems. Specifications and manufacturing controls were placed on these materials and, once qualified, a no-change policy was instituted. The current material is acceptable; however, prepreg variability does not always accommodate the requirements of automation. The advanced solid rocket motor requires material with less variability for automated manufacturing. An advanced solid rocket motor materials team, composed of NASA, Thiokol, Aerojet, SRI, and Lockheed specialists, along with materials suppliers ICI Fiberite/Polycarbon, BP Chemicals/Hitco, and Amoco, embarked on a program to improve the current materials. The program consisted of heat treatment studies and standard and low-density material improvements evaluation. Improvements evaluated included fiber/fabric heat treatments, weave variations, resin application methods, process controls, and monitors.

  14. Nozzle Initiative Industry Advisory Committee on Standardization of Carbon-Phenolic Test Methods and Specifications

    NASA Technical Reports Server (NTRS)

    Bull, William B. (Compiler); Pinoli, Pat C. (Compiler); Upton, Cindy G. (Compiler); Day, Tony (Compiler); Hill, Keith (Compiler); Stone, Frank (Compiler); Hall, William B.

    1994-01-01

    This report is a compendium of the presentations of the 12th biannual meeting of the Industry Advisory Committee under the Solid Propulsion Integrity Program. A complete transcript of the welcoming talks is provided. Presentation outlines and overheads are included for the other sessions: SPIP Overview, Past, Current and Future Activity; Test Methods Manual and Video Tape Library; Air Force Developed Computer Aided Cure Program and SPC/TQM Experience; Magneto-Optical mapper (MOM), Joint Army/NASA program to assess composite integrity; Permeability Testing; Moisture Effusion Testing by Karl Fischer Analysis; Statistical Analysis of Acceptance Test Data; NMR Phenolic Resin Advancement; Constituent Testing Highlights on the LDC Optimization Program; Carbon Sulfur Study, Performance Related Testing; Current Rayon Specifications and Future Availability; RSRM/SPC Implementation; SRM Test Methods, Delta/Titan/FBM/RSRM; and Open Forum on Performance Based Acceptance Testing -- Industry Experience.

  15. Genotoxic potentials of lifestyles assessed by urinary mutagenicity.

    PubMed

    Mure, K; Morimoto, K

    1994-09-01

    The relationships between lifestyles and urinary mutagenicity were investigated by using blue rayon extraction from 33 healthy male workers' urine. Subjects were classified into three groups, as "good", "moderate", and "poor" according to their responses on a questionnaire regarding eight health practices (cigarette smoking, alcohol consumption, eating breakfast, hours of sleep, hours of work, physical exercise, caring about nutritional balance, mental stress). The better lifestyle groups exhibited the lower mutagenicity. Subjects in a "good" group showed significantly lower urinary mutagenicity than those both in a "moderate" (p < 0.05) and a "poor" (p < 0.05) groups at fraction number 1 to 3 that were given after ingesting fried beef. These tendencies also found at fraction number 8 to 9 that were given after smoking, although not significant. The lifestyles were significantly associated with the urinary mutagenicity, and the results suggested that not only particular lifestyle factor but also some combinations with smoking significantly enhanced with the urinary mutagenicity.

  16. Étude par diffraction des rayons X de la nitruration plasma d'un acier 304L Influence sur l'oxydation à 1000 ^{circ}C

    NASA Astrophysics Data System (ADS)

    Marot, L.; Buscail, H.; Straboni, A.; Riffard, F.; Caudron, E.; Cueff, R.

    2002-07-01

    This work presents the influence of various nitridation parameters on the 304L steel oxidation at 1000 ^{circ}C, in air under atmospheric pressure. Nitridation temperatures were ranging between 300 ^{circ}C and 430 ^{circ}C with exposure times lasting from 2 to 8 hours. At 300 and 430 ^{circ}C, the nitridation treatment leads to the solid solution surface formation γ-N without any nitride formation. After oxidation at 1000 ^{circ}C of blank specimens, X ray diffraction reveals the FeCr2O4 spinel formation. This oxide does not act as a good diffusion barrier. With nitrogen treated specimens, the higher the nitridation temperature is and the longer the exposure time is, better is the oxidation behaviour at 1000 ^{circ}C. We then observe that the Cr{1,3}Fe{0,7}O3 oxide is more present in the oxide sale from the very beginning of the oxidation test which is correlated to a final lower mass gain. Cette étude porte sur l'influence des paramètres de nitruration plasma sur l'oxydation de l'acier 304L à 1000 ^{circ}C, sous air, à la pression atmosphérique. Les températures employées lors de la nitruration ont été de 300 ^{circ}C et 430 ^{circ}C pour des durées de nitruration variant entre 2 et 8 heures. A 300 et 430 ^{circ}C, la nitruration conduit à la formation d'une solution solide γ-N en surface sans provoquer la formation de nitrures. Après oxydation à 1000 ^{circ}C du 304L non nitruré, la diffraction des rayons X révèle la formation d'une couche de type spinelle FeCr2O4 qui ne semble pas jouer le rôle de barrière de diffusion. Pour les échantillons préalablement nitrurés, plus la température de nitruration est élevée et plus la durée du traitement est longue, meilleur est le comportement en oxydation. Nous observons alors l'oxyde Cr{1,3}Fe{0,7}O3 en proportion importante dès le début de l'oxydation et une prise de masse finale plus faible.

  17. Transitions de phase dans le oxyde de yttrium vanadium

    NASA Astrophysics Data System (ADS)

    Roberge, Benoit

    Dans le mémoire qui suit, les ordres structural, magnétiques et orbital dans le YVO3 sont étudiés avec l'aide de la diffraction des rayons X,de la spectroscopie Raman et de la technique de la cavité résonnante hyperfréquence. L'objectif premier consiste à observer l'évolution de ces ordres en fonction de la température. Le mémoire met ensuite en évidence le couplage entre les différents ordres cohabitants dans le YVO3 . Les mesures effectuées par la diffraction des rayons X permettent de mesurer le caractère polycrystallin des échantillons du YVO 3. Une comparaison de nos mesures avec des mesures de diffraction des rayons X faites sur la poudre de YVO3 indique la faible présence de maclage. Les mesures effectuées avec la technique de résonnance hyperfréquence permettent de suivre l'évolution de la constante diélectrique en fonction de la température. Les changements impliquant l'ordre orbital se manifestent de manière évidente dans la constante diélectrique à 200 K et à 77 K. La transition diélectrique détectée à 77 K est une transition de premier ordre. Un couplage entre les propriétés diélectriques et magnétiques est observable à la température de Néel à 114 K. L'effet d'un champ magnétique fixe sur la température de transition de l'ordre orbital survenant à 77 K est également remarquable. Cela indique un couplage magnétodiélectrique démontrant ainsi le caractère multiferroïque du YVO 3. Finalement, l'observation d'un mécanisme de relaxation pouvant être modélisé par le modèle d'Havriliak-Negami est observé en dessous de 77 K. En utilisant le modèle d'Arrhénius et le modèle d'Havriliak-Negami, on peut caractériser le mécanisme avec son énergie d'activation et son temps de relaxation. Les mesures effectuées en spectroscopie Raman permettent de suivre l'évolution de la structure du YVO3 en fonction de la température. Les deux changements structuraux survenant à 200 K et 77 K sont observés. Le couplage entre le réseau et l'ordre orbital se manifeste par une augmentation de l'anharmonicité qui se traduit par une augmentation de l'intensité des processus de deuxième et troisième ordres. Les différentes théories expliquant comment l'ordre orbital interagit avec le réseau cristallin seront abordées en mettant l'accent sur la théorie de Van den Brink ['] qui réflète le mieux la réalité. Une comparaison de nos mesures avec d'autres travaux en spectroscopie Raman effectués sur le YVO3 sera également effectuée. Le couplage entre le réseau et l'ordre magnétique s'observe par la présence d'excitations magnétiques dans les spectres Raman et par la présence d'un ramollissement/durcissement survenant à la température de Néel. La théorie de Granado expliquant le phénomène de durcissement/ramollissement sera discutée.

  18. Ingestion of microplastics by commercial fish off the Portuguese coast.

    PubMed

    Neves, Diogo; Sobral, Paula; Ferreira, Joana Lia; Pereira, Tânia

    2015-12-15

    The digestive tract contents of 263 individuals from 26 species of commercial fish were examined for microplastics. These were found in 17 species, corresponding to 19.8% of the fish of which 32.7% had ingested more than one microplastic. Of all the fish that ingested microplastics, 63.5% was benthic and 36.5% pelagic species. A total of 73 microplastics were recorded, 48 (65.8%) being fibres and 25 (34.2%) being fragments. Polymers were polypropylene, polyethylene, alkyd resin, rayon, polyester, nylon and acrylic. The mean of ingested microplastics was 0.27 ± 0.63 per fish, (n=263). Pelagic fish ingested more particles and benthic fish ingested more fibres, but no significant differences were found. Fish with the highest number of microplastics were from the mouth of the Tagus river. Scomber japonicus registered the highest mean of ingested microplastics, suggesting its potential as indicator species to monitor and investigate trends in ingested litter, in the MSFD marine regions. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Detection of Bordetella pertussis in Infants Suspected to have Whooping Cough.

    PubMed

    Hajia, Massoud; Rahbar, Mohammad; Fallah, Fatemeh; Safadel, Nooshafarin

    2012-01-01

    Even with high coverage of vaccination programs, Bordetella pertussis is still reported in various countries. It causes a high rate of mortality and morbidity in infants while it could be asymptomatic in adults. At the present study, we are going to evaluate the frequency of B. pertussis among received specimens. This cross-sectional study was performed on 138 children under one year who were suspected to have whooping cough from October 2008 to March in 2011. Nasopharyngeal dacron and rayon swabs and sera were used for PCR and serology respectively. The mean age of the subjects was 1.9± 0.9 months. PCR was positive in 12 cases; ELISA was in agreement with PCR results except in one case that showed the specific antibody at borderline limit. The rate of reported positive results showed that pertussis not only is still present in the community, but the number of the asymptomatic cases who are able to transmit the disease may be considerable.

  20. Electrospinning of Biodegradable and Biocompatible Nanofiber Patches from Solutions of ``Green'' Materials for Plant Protection against Fungi Attack

    NASA Astrophysics Data System (ADS)

    Sett, Soumyadip; Lee, Minwook; Yarin, Alexander; Moghadam, S. M. Alavi; Meinke, Matthias; Schroeder, Wolfgang

    2015-11-01

    Biodegradable and biocompatible soy protein/petroleum-derived polymer monolithic fibers containing adhesives were electrospun on commercial rayon pads. The polymers used, PVA and PCL, are widely used in the biomedical industry, including such applications as drug delivery and scaffold manufacturing. Soy protein is an abundant waste of SoyDiesel production, and is widely used as a nutrient. The soy content in our fibers was as high as 40% w/w. Four different adhesives, including ordinary wood glue, repositionable glue and FDA-approved pressure-sensitive glue were used for electrospinning and electrospraying. The normal and shear adhesive strengths of the patches developed in this work were measured and compared. The adhesive strength was sufficient enough to withstand normal atmospheric conditions. These biodegradable and biocompatible nano-textured patches are ready to be used on prune locations without being carried away by wind and will protect plants against fungi attack at these locations, preventing diseases like Vine Decline.

  1. Occurrence of microplastics in the gastrointestinal tract of pelagic and demersal fish from the English Channel.

    PubMed

    Lusher, A L; McHugh, M; Thompson, R C

    2013-02-15

    Microplastics are present in marine habitats worldwide and laboratory studies show this material can be ingested, yet data on abundance in natural populations is limited. This study documents microplastics in 10 species of fish from the English Channel. 504 Fish were examined and plastics found in the gastrointestinal tracts of 36.5%. All five pelagic species and all five demersal species had ingested plastic. Of the 184 fish that had ingested plastic the average number of pieces per fish was 1.90±0.10. A total of 351 pieces of plastic were identified using FT-IR Spectroscopy; polyamide (35.6%) and the semi-synthetic cellulosic material, rayon (57.8%) were most common. There was no significant difference between the abundance of plastic ingested by pelagic and demersal fish. Hence, microplastic ingestion appears to be common, in relatively small quantities, across a range of fish species irrespective of feeding habitat. Further work is needed to establish the potential consequences. Copyright © 2012 Elsevier Ltd. All rights reserved.

  2. Evolutions structurales et effets de pression dans des céramiques supraconductrices à haute T_c

    NASA Astrophysics Data System (ADS)

    Gavarri, J. R.; Carel, C.; Monnereau, O.; Vacquier, G.; Vettier, C.; Hewat, A. W.

    1991-11-01

    Using structural evolution data and a method permitting the calculation of elastic constants and Grüneisen parameters, the thermal expansion of two high T_c superconductors is interpreted. It is shown that the superconductors YBaCuO (123) and BiSrCaCuO (2212) present strongly different elastic and anharmonic properties. En appliquant une méthode déjà mise au point sur d'autres composés (Gavarri, 1981), l'évolution structurale de deux supraconducteurs à haute T_c est interprétée par le biais de leurs compressibilités anisotropes et de leurs coefficients de Grüneisen, obtenus par diffraction de neutrons et de rayons X. On montre ici que les supraconducteurs YBaCuO (123) et BiSrCaCuO (2212) diffèrent considérablement par leurs compressibilités anisotropes et par leurs coefficients de Grüneisen.

  3. The Semipalatinsk nuclear test site: a first analysis of solid cancer incidence (selected sites) due to test-related radiation.

    PubMed

    Gusev, B I; Rosenson, R I; Abylkassimova, Z N

    1998-10-01

    Since 1956, cancer incidences have been analysed in several rayons of the Semipalatinsk oblast, with cross-sectional analyses being conducted every 5 years. Data on different tumor localizations were recorded within a heavily contaminated so-called main area of nine villages (estimated average effective equivalent dose about 2000 mSv) and a so-called control area (estimated average effective equivalent dose about 70 mSv), each including approximately 10000 persons. Up to 1970, the excess cancer incidence in the exposed villages was observed to have increased; after 1970, a decrease was noted, followed by a second increase in the late 1980s. The main sites of excess cancer included the esophagus, stomach, and liver. Up to 1970, the esophagus cancer incidence was predominant, but it decreased thereafter, while the incidence of stomach and liver cancers increased. The second peak of excess cancer rates was mainly due to lung, breast, and thyroid carcinomas.

  4. Influence du traitement ionisant par rayonnement γ sur le pouvoir antioxydant de fractions polyphénoliques issues de substances d'origine végétale

    NASA Astrophysics Data System (ADS)

    Stuyck, S.; Connaulte, J.; Lesgards, G.; Prost, M.; Raffi, J.

    1998-04-01

    Ionizing radiation of vegetables is a cleaning up and preservation physical treatment which consists in submitting them to γ radiation, X radiation or electrons beam. This study deals with the influence of γ radiation on antioxidative effect of vegetables polyphenolic parts. In that purpose, we use a simple biological test based on erythrocytes haemolysis. Le traitement ionisant des produits végétaux est un procédé physique d'assainissement et de conservation qui consiste à les soumettre à l'action de rayonnements γ, de rayons X ou de faisceaux d'électrons. Ce travail porte sur l'étude de l'influence des rayonnements γ sur le pouvoir antioxydant de fractions polyphénoliques issues de substances d'origine végétale. Pour cela, un test biologique basé sur l'hémolyse d'érythrocytes est utilisé.

  5. Etude microdosimetrique de l'influence des materiaux sur l'efficacite biologique d'une source d'iode-125

    NASA Astrophysics Data System (ADS)

    Taschereau, Richard

    Cette these concerne les implants permanents pour la prostate. Les isotopes employes, le 103Pd et l'125I, semblent produire les memes resultats cliniques: le premier a cause d'une radiation plus efficace et le second a cause de sa demi-vie plus longue. La recherche utilise le cadre theorique de la microdosimetrie et des simulations Monte Carlo. Elle propose d'employer le spectre d'ejection dans le calcul de l'efficacite; ce changement fait passer l'efficacite relative du 103Pd de 10% a 5%. Elle montre ensuite qu'il est possible d'ameliorer l'efficacite de la radiation de 125I par l'exploitation des rayons X caracteristiques de la capsule. Une source amelioree faite de molybdene et d'yttrium est donnee en exemple. Elle procure une radiation de 5--7% plus efficace, ce qui surclasse les deux sources existantes. Les applications ne se limitent pas au traitement de la prostate; le traitement du melanome oculaire et la curietherapie endovasculaire pourraient en beneficier.

  6. Microplastic abundance, distribution and composition along a latitudinal gradient in the Atlantic Ocean.

    PubMed

    Kanhai, La Daana K; Officer, Rick; Lyashevska, Olga; Thompson, Richard C; O'Connor, Ian

    2017-02-15

    Microplastics in the world's oceans are a global concern due to the potential threat they pose to marine organisms. This study investigated microplastic abundance, distribution and composition in the Atlantic Ocean on a transect from the Bay of Biscay to Cape Town, South Africa. Microplastics were sampled from sub-surface waters using the underway system of the RV Polarstern. Potential microplastics were isolated from samples and FT-IR spectroscopy was used to identify polymer types. Of the particles analysed, 63% were rayon and 37% were synthetic polymers. The majority of microplastics were identified as polyesters (49%) and blends of polyamide or acrylic/polyester (43%). Overall, fibres (94%) were predominant. Average microplastic abundance in the Atlantic Ocean was 1.15±1.45particlesm -3 . Of the 76 samples, 14 were from the Benguela upwelling and there was no statistically significant difference in microplastic abundance between upwelled and non-upwelled sites. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Characterization of Textile-Insulated Capacitive Biosensors

    PubMed Central

    Ng, Charn Loong; Reaz, Mamun Bin Ibne

    2017-01-01

    Capacitive biosensors are an emerging technology revolutionizing wearable sensing systems and personal healthcare devices. They are capable of continuously measuring bioelectrical signals from the human body while utilizing textiles as an insulator. Different textile types have their own unique properties that alter skin-electrode capacitance and the performance of capacitive biosensors. This paper aims to identify the best textile insulator to be used with capacitive biosensors by analysing the characteristics of 6 types of common textile materials (cotton, linen, rayon, nylon, polyester, and PVC-textile) while evaluating their impact on the performance of a capacitive biosensor. A textile-insulated capacitive (TEX-C) biosensor was developed and validated on 3 subjects. Experimental results revealed that higher skin-electrode capacitance of a TEX-C biosensor yields a lower noise floor and better signal quality. Natural fabric such as cotton and linen were the two best insulating materials to integrate with a capacitive biosensor. They yielded the lowest noise floor of 2 mV and achieved consistent electromyography (EMG) signals measurements throughout the performance test. PMID:28287493

  8. Vapor Grown Carbon Fiber/Phenolic Matrix Composites for Rocket Nozzles and Heat Shields

    NASA Technical Reports Server (NTRS)

    Patton, R. D.; Pittman, C. U., Jr.; Wang, L.; Day, A.; Hill, J. R.

    2001-01-01

    The ablation and mechanical and thermal properties of vapor grown carbon fiber (VGCF)/phenolic resin composites were evaluated to determine the potential of using this material in solid rocket motor nozzles. Composite specimens with varying VGCF loading (30%-50% wt) including one sample with ex-rayon carbon fiber plies were prepared and exposed to a plasma torch for 20 s with a heat flux of 16.5 MW/sq m at approximately 1650 C. Low erosion rates and little char formation were observed, confirming that these materials were promising for rocket motor nozzle materials. When fiber loadings increased, mechanical properties and ablative properties improved. The VGCF composites had low thermal conductivities (approximately 0.56 W/m-C) indicating they were good insulating materials. If a 65% fiber loading in VGCF composite can be achieved, then ablative properties are projected to be comparable to or better than the composite material currently used on the Space Shuttle Reusable Solid Rocket Motor (RSRM).

  9. NMR, symmetry elements, structure and phase transitions in the argyrodite family

    NASA Astrophysics Data System (ADS)

    Gaudin, E.; Taulelle, F.; Boucher, F.; Evain, M.

    1998-02-01

    Cu7PSe6 belongs to a family of structures known as the argyrodites. It undergoes two phases transitions. The high temperature phase has been determined by X-ray diffraction. It has a Foverline{4}3m space group. Medium temperature phases have been refined using a non-harmonic technique and the space group proposed is P213. The low temperature phase had an apparent space group of Foverline{4}3m also. Use of X-ray diffraction and NMR together has allowed to determine the space groups of all phases as being respectively Foverline{4}3m, P213 and Pmn21. Positioning of disordered coppers in the structure is therefore possible and the structure can be described by connex polyhedra of PSe3-4 and SeCux-2_x. The phase transitions can be understood by an ordered motion of SeCux-2x polyhedra. If these polyhedra set in motion independently two transitions are to be observed, if they are coupled only one is observed. Cu7PSe6 appartient à une famille de composés connus sous le nom d'argyrodites. Cu7PSe6 possède deux transitions de phase. La structure de haute température a été déterminée par diffraction des rayons X. Elle se décrit par le groupe d'espace Foverline{4}3m. La phase de moyenne température a été raffinée en utilisant une technique non-harmonique et le groupe d'espace proposé est P213. La phase de basse température possède également un groupe d'espace apparent Foverline{4}3m. En utilisant ensemble la diffraction des rayons X et la RMN, il a été possible de déterminer les groupes d'espace de toutes les phases comme étant respectivement Foverline{4}3m, P213 et Pmn21. Placer les atomes de cuivre, désordonnés, dans la structure devient alors possible et la structure peut se décrire comme un ensemble de polyèdres connexes de PSe3-4 et SeCux-2_x. Les transitions de phases se décrivent alors comme des mouvements ordonnés des polyèdres SeCux-2_x. Si ces polyèdres se mettent en mouvement indépendamment, deux transitions de phases sont attendues, si leur mise en mouvement est couplée, une seule est observée.

  10. Improving Mechanical Properties of Molded Silicone Rubber for Soft Robotics Through Fabric Compositing.

    PubMed

    Wang, Yue; Gregory, Cherry; Minor, Mark A

    2018-06-01

    Molded silicone rubbers are common in manufacturing of soft robotic parts, but they are often prone to tears, punctures, and tensile failures when strained. In this article, we present a fabric compositing method for improving the mechanical properties of soft robotic parts by creating a fabric/rubber composite that increases the strength and durability of the molded rubber. Comprehensive ASTM material tests evaluating the strength, tear resistance, and puncture resistance are conducted on multiple composites embedded with different fabrics, including polyester, nylon, silk, cotton, rayon, and several blended fabrics. Results show that strong fabrics increase the strength and durability of the composite, valuable in pneumatic soft robotic applications, while elastic fabrics maintain elasticity and enhance tear strength, suitable for robotic skins or soft strain sensors. Two case studies then validate the proposed benefits of the fabric compositing for soft robotic pressure vessel applications and soft strain sensor applications. Evaluations of the fabric/rubber composite samples and devices indicate that such methods are effective for improving mechanical properties of soft robotic parts, resulting in parts that can have customized stiffness, strength, and vastly improved durability.

  11. Occurrence Characteristics of Microplastic in Secondary Sewage Treatment Plant in Shanghai,China.

    NASA Astrophysics Data System (ADS)

    Bai, M.; Zhao, S.; Li, D.

    2017-12-01

    As emerging pollutants, microplastics (MPs) are of concern worldwide. Due to plenty of microbeads and synthetic fibers presenting in the effluent of waste water treatment plants (WWTPs), WWTPs have been regarded as important point sources of MP into the sea. Currently, information of microplastics from WWTPs in China is limited. Herein, we studied the MP contamination of a sewage plant in Shanghai by analyzing water and sludge samples with fourier transform infrared spectroscopy. The abundances of MP in the influent, mixed water, effluent and sludge four stages are respectively 117 n/L, 90 n/L, 52 n/L and 181 n/50g(wet weight). The removal efficiency of MP in the current WWTP is 55.6%. Fiber is the most common shape type. Rayon is the most type in effluent and mixed water while synthetic leather account for the largest percentage in influent and sludge. This study firstly discussed the occurrence characteristics of microplastics in the WWTP of China and confirmed that WWTP is a source of MPs inputting into aquatic environments.

  12. Skin graft donor site: a procedure for a faster healing.

    PubMed

    Cuomo, Roberto; Grimaldi, Luca; Brandi, Cesare; Nisi, Giuseppe; D'Aniello, Carlo

    2017-10-23

    The authors want to evaluate the efficacy of fibrillary tabotamp dressing in skin graft-donor site. A comparison was made with Vaseline gauzes. Tabotamp is an absorbable haemostatic product of Ethicon (Johnson and Johnson) obtained by sterile and oxidized regenerated cellulose (Rayon). It is used for mild to moderate bleeding. 276 patients were subject to skin graft and divided into two group: Group A and Group B. The donor site of patients in Group A was medicated with fibrillary tabotamp, while the patients of Group B were medicated only with Vaseline gauze. We recorded infection, timing of healing, number of dressing change, the pain felt during and after the dressing change with visual analog scale (VAS) and a questionnaire. Patients allocated in Group A healed faster than the Group B. Questionnaires and VAS analysis showed lower pain felt, lower intake of pain drugs and lower infection rate in the Group A than the Group B. Analysis of coast showed lower dressing change in Group A than the Group B. We believe that the use of tabotamp is a very viable alternative to improve healing.

  13. The Extraction and Recovery Efficiency of Pure DNA for Different Types of Swabs.

    PubMed

    Bruijns, Brigitte B; Tiggelaar, Roald M; Gardeniers, Han

    2018-06-11

    The extraction and recovery efficiency of swabs used to collect evidence at crime scenes is relatively low (typically <50%) for bacterial spores and body fluids. Cell-free deoxyribonucleic acid (DNA) is an interesting alternative compared to whole cells as a source for forensic analysis, but extraction and recovery from swabs has not been tested before using pure DNA. In this study cotton, foam, nylon flocked, polyester and rayon swabs are investigated in order to collect pure DNA isolated from saliva samples. The morphology and absorption capacity of swabs is studied. Extraction and recovery efficiencies are determined and compared to the maximum theoretical efficiency. The results indicate that a substantial part of DNA is not extracted from the swab and some types of swab seem to bind effectively with DNA. The efficiency of the different types of swab never exceeds 50%. The nylon flocked 4N6FLOQSwab used for buccal sampling performs the best. © 2018 The Authors. Journal of Forensic Sciences published by Wiley Periodicals, Inc. on behalf of American Academy of Forensic Sciences.

  14. Contribution to the Study of Nuclear Interactions at Several Tens of Bev by Means of Cosmic Radiations (thesis); CONTRIBUTION A L'ETUDE DES INTERACTIONS NUCLEAIRES DE PLUSIEURS DIZAINES DE Gev., AU MOYEN DES RAYONS COSMIQUES (THESES)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pelletier, C.

    1960-01-01

    The secondaries produced by the interaction of highenergy cosmic radiation with aluminum were studied with Wilson chambers placed in a magnetic field. From 9600 photographs made, 117 interactions of charged particles with energy higher than 10 Bev in aluminum were selected. These photographs were obtained with the apparatus installed at the Observatory of the Pic du Midi de Bigorre. This apparatus is described. The quantities of motion and the emission direction of charged secondaries of each interaction were determined. The measurements and the methods of calculation are described. The results obtained on charged secondaries and unstable particles are reported. Themore » selection of the interactions which occurred with only one nucleon of the aluminum nucleus is discussed. These interactions were studied in the center-of-mass system of the interacting particles. The results obtained are compared with the predictions of the principal theoreticat models of nucleon-nucleon interactions. (trauth)« less

  15. Leukopenia, Neutropenia and Bacteremia in Mouse Following Two Successive Irradiations by X-Rays; LEUCOPENIE, NEUTROPENIE ET BACTERIEMIE CHEZ LA SOURIS, APRES DEUX IRRADIATIONS SUCCESSIVES PAR RAYONS X

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mewissen, D.J.; Betz, E.H.; Betz-Bareau, M.

    A study was made of the course of leukopenia, neutropenia, and bacteremia in mice subjected to whole body x radiation to determine a possible correlation between their variations and the bimodal nature of the lethal response. The mice, five days apart, were subjected to two whole-body x irradiations of 220 r each. The mice were sacrificed at intervals of 9, 12, 14, 19, 29, and 40 days after the first exposure. Spleen and cardiac blood examinations were made on each mouse. The results showed that the percentage of animals in which the leukopenia was marked passed through maxima near themore » 12th day and the 22nd day. The maxima coincide in time with the highest mortality rates observed in irradiated mice. The neutropenia goes through two critical minima which are essentially contemporaneous with these rates. A bacteremia was observed only in the vicinity of the first maximum in the mortality rate. (J.S.R.)« less

  16. Anthropogenic impacts on deep submarine canyons of the western Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Sanchez-Vidal, A.; Tubau, X.; Llorca, M.; Woodall, L.; Canals, M.; Farré, M.; Barceló, D.; Thompson, R.

    2016-02-01

    Submarine canyons are seafloor geomorphic features connecting the shallow coastal ocean to the deep continental margin and basin. Often considered biodiversity hotspots, submarine canyons have been identified as preferential pathways for water, sediment, pollutant and litter transfers from the coastal to the deep ocean. Here we provide insights on the presence of some of the most insidious man-made debris and substances in submarine canyons of the western Mediterranean Sea, which are relevant to achieve a "Good Environmental Status" by 2020 as outlined in the European Union's ambitious Marine Strategy Framework Directive. Ranked by size on a decreasing basis, we review the origin, distribution and transport mechanisms of i) marine litter, including plastic, lost fishing gear and metallic objects; ii) microplastics in the form of fibers of rayon, polyester, polyamide and acetates; and iii) persistent organic pollutants including the toxic and persistent perfluoroalkyl substances. This integrated analysis allows us to understand the pivotal role of atmospheric driven oceanographic processes occurring in Mediterranean deep canyons (dense shelf water cascading, coastal storms) in spreading any type of man-made compound to the deep sea, where they sink and accumulate before getting buried.

  17. Comparison of synthetic membranes in the development of an in vitro feeding system for Dermanyssus gallinae.

    PubMed

    Harrington, D W J; Guy, J H; Robinson, K; Sparagano, O A E

    2010-04-01

    Although artificial feeding models for the poultry red mite (Dermanyssus gallinae) most frequently use biological membranes consisting of day-old chick skin, there are ethical considerations associated with the use of skin. The few studies reported in the literature that have investigated the use of synthetic membranes to feed D. gallinae in vitro have reported limited success. The current study describes an investigation into the use of synthetic membranes made from either Nescofilm or rayon and silicone, used either alone or in combination with different feather or skin extracts, as well as the use of capillary tubes. In all, 12 different treatments were used, and the feeding rate of D. gallinae was compared to that of day-old chick skin. Allowing mites to feed on a membrane consisting of Nescofilm with a skin extract resulted in the highest proportion of mites feeding (32.3%), which was not significantly different to the feeding rate of mites on day-old chick skin (38.8%). This study confirms that synthetic membranes can be used to feed D. gallinae artificially. Further optimization of the membrane and mite storage conditions is still necessary, but the study demonstrates a proof of concept.

  18. Study of the chain conformation of thermotropic nematic main chain polyesters

    NASA Astrophysics Data System (ADS)

    Li, M. H.; Brûlet, A.; Cotton, J. P.; Davidson, P.; Strazielle, C.; Keller, P.

    1994-10-01

    The conformation of main chain mesomorphic polyesters is studied by small angle neutron scattering (SANS) in the isotropic and in the nematic phases, by using mixtures of deuterated and undeuterated polymers. Particular attention is given to neglect the transesterification effects occurring mainly at high temperature for these LC polymers. In the isotropic phase, despite the presence of long rigid mesogenic groups, the LC polyester chains have a Gaussian conformation shown by the variation of the radius of gyration as a function of the molecular weight. This result is confirmed from the scattering variation in the intermediate range of the scattering vector. In the nematic phase, the SANS data are well fitted to a model of cylinder, in which the main chain polymer is confined. In the unoriented phase, the measurements in the intermediate range give the values of the radii of cylinders : they lie in between 10 Å and 19 Å depending on the degree of polymerization of chains. In the oriented nematic phase, the scattering patterns are highly anisotropic : they correspond to very long, thin and well-oriented cylinders. We have calculated the fully extended chain lengths using for the monomer length that measured in situ by X-ray diffraction. Then the comparison of this length with the measured height of the cylinders gives the existence of hairpins and their number per chain. For the short chain, the conformation is almost completely elongated in the nematic direction, whereas hairpin defects appear in longer chains. Their number decreases slightly with decreasing temperature. The orientational fluctuations of cylinders relatively to the nematic director are weak as shown from the high values of their order parameter (P_2 > 0.9). These results are discussed for two spacer lengths as a function of the molecular weight and of the temperature. La conformation de polyesters linéaires mésomorphes est étudiée par diffusion de neutrons aux petits angles (DNPA) dans les phases isotrope et nématique sur des mélanges de polymères hydrogénés et deutériés. Les conditions expérimentales ont été choisies afin de pouvoir négliger les effets de la transestérification obtenus à haute température avec cette famille de polymères cristaux liquides. Dans la phase isotrope, en dépit de la présence de longs et rigides groupements mésogènes, les chaînes de polymères ont une conformation gaussienne, comme le montre la variation du rayon de giration en fonction de la masse moléculaire. Ce résultat est confirmé par les mesures faites dans le domaine intermédiaire du vecteur de diffusion. Dans la phase nématique, les données de DNPA sont bien ajustées par un modèle de cylindre dans lequel la chaîne de polymère est confinée. Dans la phase non orientée, les mesures faites dans le domaine intermédiaire donnent les valeurs des rayons des cylindres (compris entre 10 Å et 19 Å selon le degré de polymérisation des chaînes). Dans la phase nématique orientée, les figures de diffusion sont très anisotropes et correspondent à de longs et étroits cylindres bien orientés. La longueur de la chaîne totalement étirée est calculée à partir de la longueur du monomère mesurée par diffraction de rayons X. Par comparaison avec la hauteur du cylindre mesurée en DNPA, nous déduisons l'existence des épingles à cheveux et leur nombre par chaîne. La conformation d'une chaîne courte est complètement étirée dans la direction du champ nématique, alors que des défauts du type épingles à cheveux apparaissent dans les chaînes plus longues. Le nombre de ces défauts décroît légèrement en diminuant la température. Les fluctuations d'orientation des cylindres autour de la direction du champ nématique sont faibles comme le montrent les valeurs élevées des paramètres d'ordre des cylindres (P_2 > 0,9). Les résultats sont discutés, pour deux longueurs d'espaceur, en fonction de la masse moléculaire et de la température.

  19. X-ray scattering by edge-dislocations in the S_A phase of mesomorphic side chain polyacrylates

    NASA Astrophysics Data System (ADS)

    Davidson, P.; Pansu, B.; Levelut, A. M.; Strzelecki, L.

    1991-01-01

    The X-ray diffraction patterns of mesomorphic side chain polymers in the S_A phase present diffuse streaks in shape of “butterfly wings”. We show that this diffuse scattering may be due to the presence of edge dislocations. On the basis of a previous description of edge dislocations within the framework of the elastic continuum theory of the S_A phase given by De Gennes, we have calculated the Fourier transform of the deformation field. Optical diffraction experiments on sketches of defects have also been made to reproduce the X-ray scattering patterns. Both methods show that this diffuse scattering may indeed be due to the presence of edge dislocations. Their density may be roughly estimated to some 10^8/cm^2. The size of their cores should be only a few Ångströms. From the decay of their elastic deformation field, a typical length λ = (K/B)^{1/2}≈ 1,5 Å can be obtained which shows that the elastic constant B of compression of the layers should be about two orders of magnitude larger in the “polymeric” S_A phase than in the “conventional” one. Les clichés de diffraction des rayons X par des polymères mésomorphes en peigne, en phase S_A, présentent des trainées diffuses en forme d'“ ailes de papillon ”. Nous montrons que cette diffusion diffuse peut s'expliquer par la présence de dislocations-coin. En partant de la description des dislocations-coin donnée par De Gennes dans le cadre de la théorie du continuum élastique de la phase S_A, nous avons calculé la transformée de Fourier du champ de déformation. Des expériences de diffraction optique sur des modèles de défauts ont aussi été effectuées afin de reproduire les clichés de diffraction des rayons X. Les deux méthodes montrent que cette diffusion diffuse peut en effet bien s'expliquer par la présence de dislocations-coin. Leur densité a été grossièrement estimée à quelques 10^8/cm^2. La taille de leurs coeurs ne devrait pas dépasser quelques Ångströms. D'après l'allure du champ de déformation élastique, on peut tirer une longueur typique λ = (K/B)^{1/2}≈ 1,5 Å, ce qui montre que la constante élastique B de compression des couches devrait être environ 100 fois plus élevée en phase S_A “ polymérique ” qu'en phase S_A “ usuelle ”.

  20. Mesure de haute resolution de la fonction de distribution radiale du silicium amorphe pur

    NASA Astrophysics Data System (ADS)

    Laaziri, Khalid

    1999-11-01

    Cette these porte sur l'etude de la structure du silicium amorphe prepare par irradiation ionique. Elle presente des mesures de diffraction de rayons X sur de la poudre de silicium cristallin, du silicium amorphe relaxe et non relaxe, ainsi que tous les developpements mathematiques et physiques necessaires pour extraire la fonction de distribution radiale correspondant a chaque echantillon. Au Chapitre I, nous presentons une methode de fabrication de membranes minces de silicium amorphe pur. Il y a deux etapes majeures lors du processus de fabrication: l'implantation ionique, afin de creer une couche amorphe de plusieurs microns et l'attaque chimique, pour enlever le reste du materiau cristallin. Nous avons caracterise premierement les membranes de silicium amorphe par spectroscopie Raman pour verifier qu'il ne reste plus de trace de materiau cristallin dans les films amorphes. Une deuxieme caracterisation par detection de recul elastique (ERD-TOF) sur ces memes membranes a montre qu'il y a moins de 0.1% atomique de contaminants tels que l'oxygene, le carbone, et l'hydrogene. Au Chapitre II, nous proposons une nouvelle methode de correction de la contribution inelastique "Compton" des spectres de diffusion totale afin d'extraire les pics de diffusion elastique, responsable de la diffraction de Bragg. L'article presente tout d'abord une description simplifiee d'une theorie sur la diffusion inelastique dite "Impulse Approximation" (IA) qui permet de calculer des profils de Compton en fonction de l'energie et de l'angle de diffusion 2theta. Ces profils sont utilises comme fonction de lissage de la diffusion Compton experimentale. Pour lisser les pics de diffusion elastique, nous avons utilise une fonction pic de nature asymetrique. Aux Chapitre III, nous exposons de maniere detaillee les resultats des experiences de diffraction de rayons X sur les membranes de silicium amorphe et la poudre de silicium cristallin que nous avons preparees. Nous abordons aussi les differentes etapes experimentales, d'analyse ainsi que les methodes de determination et de filtrage des transformees de Fourier des donnees de diffraction. Une comparaison des fonctions de distribution radiale du silicium amorphe relaxe et non relaxe indique que la relaxation structurelle dans le silicium amorphe est probablement due en grande partie a une annihilation des defauts plutot qu'a une reorganisation atomique globale du reseau de silicium amorphe. La deduction de la coordination des pics correspondants au premiers voisins atomiques par lissage de fonctions gaussienne indique que la coordination du silicium amorphe relaxe est de 3.88, celle du non-relaxe est de 3.79, alors que la mesure de reference sur la poudre de silicium cristallin donne une valeur de 4 tel que prevu. La sous-coordination du silicium amorphe expliquerait pourquoi sa densite est inferieure a celle du silicium cristallin. (Abstract shortened by UMI.)

  1. Natural biopolymer for preservation of microorganisms during sampling and storage.

    PubMed

    Sorokulova, Iryna; Watt, James; Olsen, Eric; Globa, Ludmila; Moore, Timothy; Barbaree, James; Vodyanoy, Vitaly

    2012-01-01

    Stability of microbial cultures during sampling and storage is a vital issue in various fields of medicine, biotechnology, food science, and forensics. We have developed a unique bacterial preservation process involving a non-toxic, water-soluble acacia gum polymer that eliminates the need for refrigerated storage of samples. The main goal of this study is to characterize the efficacy of acacia gum polymer for preservation of pathogenic bacteria (Bacillus anthracis and methicillin-resistant Staphylococcus aureus-MRSA) on different materials, used for swabbing and filtration: cotton, wool, polyester, rayon, charcoal cloth, and Whatman paper. Acacia gum polymer used for preservation of two pathogens has been shown to significantly protect bacteria during dehydration and storage in all tested samples at the range of temperatures (5-45°C for MRSA and 40-90°C for B. anthracis). Our results showed higher recovery as well as higher viability during the storage of both bacteria in all materials with acacia gum. Addition of acacia gum polymer to swabbing materials or filters will increase efficacy of sample collection and identification of pathogenic bacteria from locations such as hospitals or the environment. Proposed approach can also be used for long-term storage of culture collections, since acacia gum contributes to viability and stability of bacterial cultures. Copyright © 2011 Elsevier B.V. All rights reserved.

  2. Possibilité d'une nouvelle technologie de traitement des minerais de fer de l'Ouenza par radiométrie

    NASA Astrophysics Data System (ADS)

    Idres, A.; Bounouala, M.

    2005-05-01

    En l'absence d'une technologie fiable de traitement des haldes de minerais de fer, les caractéristiques minéralogiques et chimiques complexes et les effets néfastes des résidus miniers posent réellement un problème environnemental. A cet effet, une étude minéralogique et chimique du minerai de fer a été menée en utilisant des techniques multiples (microscopie optique, DRX, FX, MEB). En tenant compte de la nature des résidus, des échantillons représentatifs ont été testés par séparation radiométrique. Plusieurs paramètres ont été caractérisés tels que la vitesse de la bande transporteuse, le temps d'émission des rayons gamma et la granulométrie d'alimentation du procédé. Les résultats ainsi obtenus par cette méthode de séparation sont très significatifs en récupération et en teneur fer. Cependant, cette nouvelle technologie permet d'une part une meilleure valorisation des minerais de fer et d'autre part une réduction du tonnage stocké sur le carreau de la mine.

  3. Flexible ex vivo phantoms for validation of diffusion tensor tractography on a clinical scanner.

    PubMed

    Watanabe, Makoto; Aoki, Shigeki; Masutani, Yoshitaka; Abe, Osamu; Hayashi, Naoto; Masumoto, Tomohiko; Mori, Harushi; Kabasawa, Hiroyuki; Ohtomo, Kuni

    2006-11-01

    The aim of this study was to develop ex vivo diffusion tensor (DT) flexible phantoms. Materials were bundles of textile threads of cotton, monofilament nylon, rayon, and polyester bunched with spiral wrapping bands and immersed in water. DT images were acquired on a 1.5-Tesla clinical magnetic resonance scanner using echo planar imaging sequences with 15 motion probing gradient directions. DT tractography with seeding and a line-tracking method was carried out by software originally developed on a PC-based workstation. We observed relatively high fractional anisotropy on the polyester phantom and were able to reconstruct tractography. Straight tracts along the bundle were displayed when it was arranged linearly. It was easy to bend arcuately or bifurcate at one end; and tracts followed the course of the bundle, whether it was curved or branched and had good agreement with direct visual observation. Tractography with the other fibers was unsuccessful. The polyester phantom revealed a diffusion anisotropic structure according to its shape and would be utilizable repeatedly under the same conditions, differently from living central neuronal system. It would be useful to validate DT sequences and to optimize an algorithm or parameters of DT tractography software. Additionally, the flexibility of the phantom would enable us to model human axonal projections.

  4. Proposition d'un modèle expérimental pour la caractérisation de la réponse mécanique d'un composite (tissu de verre / résine époxyde)

    NASA Astrophysics Data System (ADS)

    Naceri, A.; Vautrin, A.

    2005-05-01

    L'objet de cet article est de proposer une géométrie d'éprouvette pour la caractérisation de la réponse mécanique d'un composite constitué de 12 plis de tissus de fibres de verre noyé dans une résine époxyde. Des essais de traction uniaxiale en rampe monotone réalisés sur différentes configurations géométriques d'éprouvettes avec différentes vitesses d'essais et le calcul numérique par éléments finis de la répartition des contraintes dans la zone centrale du modèle expérimental proposé, nous ont permis de justifier le choix d'une éprouvette profilée avec un rayon de 1000 mm qui présente une section réduite au centre et pour laquelle la rupture survient dans la zone centrale sans chute notable des caractéristiques mécaniques ultimes par rapport à l'éprouvette de forme parallélépipédique.

  5. Injection threshold for a star polymer inside a nanopore

    NASA Astrophysics Data System (ADS)

    Brochard-Wyart, Françoise; de Gennes, Pierre-Gilles

    A linear, flexible polymer (in dilute solution with a good solvent) enters a pore (of diameter D smaller than its gyration radius R) only when the suction flux J is larger than a threshold value Jcl ≅ kT/η (T: temperature; η: solvent viscosity). We discuss here the case of an f arm star polymer (f >> 1). The results suggest that permeation through nanopores may provide an interesting characterization of mixtures containing linear and branched polymers with the same overall molecular weight. Un polymère linéaire flexible (en solution diluée dans un bon solvant) ne pénètre dans un pore (de diamètre D inférieure à son rayon de gyration R) que si le flux d'entraînement J est supérieur à une valeur seuil Jcl ≅ kT/η (T : température ; η: viscosité du solvant). Nous étendons ici la discussion au cas d'une étoile à f branches (f >> 1). Les résultats suggèrent que la perméation dans des nanopores peut être une méthode utile pour caractériser des mélanges de polymères linéaires et branchés de même masse moléculaire globale.

  6. User experience analysis of e-TB Manager, a nationwide electronic tuberculosis recording and reporting system in Ukraine.

    PubMed

    Konduri, Niranjan; Sawyer, Kelly; Nizova, Nataliya

    2017-04-01

    Ukraine has successfully implemented e-TB Manager nationwide as its mandatory national tuberculosis registry after first introducing it in 2009. Our objective was to perform an end-of-programme evaluation after formal handover of the registry administration to Ukraine's Centre for Disease Control in 2015. We conducted a nationwide, cross-sectional, anonymous, 18-point user experience survey, and stratified the registry's transaction statistics to demonstrate usability. Contrary to initial implementation experience, older users (aged >50 years), often with limited or no computer proficiency prior to using the registry, had significantly better user experience scores for at least six of the 12 measures compared to younger users (aged 18-29 years). Using the registry for >3 years was associated with significantly higher scores for having capacity, adequacy of training received and satisfaction with the registry. Of the 5.9 million transactions over a 4-year period, nine out of 24 oblasts (regions) and Kiev city accounted for 62.5% of all transactions, and corresponded to 59% of Ukraine's tuberculosis burden. There were 437 unique active users in 486 rayons (districts) of Ukraine, demonstrating extensive reach. Our key findings complement the World Health Organization and European Respiratory Society's agenda for action on digital health to help implement the End TB Strategy.

  7. Table-top laser-driven ultrashort electron and X-ray source: the CIBER-X source project

    NASA Astrophysics Data System (ADS)

    Girardeau-Montaut, Jean-Pierre; Kiraly, Bélà; Girardeau-Montaut, Claire; Leboutet, Hubert

    2000-09-01

    We report on the development of a new laser-driven table-top ultrashort electron and X-ray source, also called the CIBER-X source . X-ray pulses are produced by a three-step process which consists of the photoelectron emission from a thin metallic photocathode illuminated by 16 ps duration laser pulses at 213 nm. The e-gun is a standard Pierce diode electrode type, in which electrons are accelerated by a cw electric field of ˜11 MV/m up to a hole made in the anode. The photoinjector produces a train of 70-80 keV electron pulses of ˜0.5 nC and 20 A peak current at a repetition rate of 10 Hz. The electrons are then transported outside the diode along a path of 20 cm length, and are focused onto a target of thullium by magnetic fields produced by two electromagnetic coils. X-rays are then produced by the impact of electrons on the target. Simulations of geometrical, electromagnetic fields and energetic characteristics of the complete source were performed previously with the assistance of the code PIXEL1 also developed at the laboratory. Finally, experimental electron and X-ray performances of the CIBER-X source as well as its application to very low dose imagery are presented and discussed. source Compacte d' Impulsions Brèves d' Electrons et de Rayons X

  8. Beta 2-microglobulin kinetics in maintenance hemodialysis: a comparison of conventional and high-flux dialyzers and the effects of dialyzer reuse.

    PubMed

    DiRaimondo, C R; Pollak, V E

    1989-05-01

    beta 2-Microglobulin (beta 2M) forms synovial and bony amyloid deposits in long-term hemodialysis patients. To define the kinetics of beta 2M during hemodialysis and the effects of dialyzer reprocessing, we measured serum beta 2M, plasma C3a, and neutrophil counts immediately predialysis; 15, 90, and 180 minutes after beginning dialysis; and 15 minutes postdialysis in ten chronic hemodialysis patients. The studies were performed during first and third uses of cuprammonium rayon and polysulfone dialyzers processed by rinsing with water, then bleach, in an automated system (Seratronics DRS 4) and then packed in 1.5% formaldehyde. Mean serum beta 2M (corrected for ultrafiltration) decreased by 16.6% +/- 18.1% with new cuprammonium dialyzers and 57.1% +/- 12.8% with new polysulfone dialyzers. Dialyzer reprocessing had no significant effect on this decline. Predialysis serum beta 2M decreased by 30.4% +/- 15.5% 1 month after switching from cuprammonium to polysulfone dialyzers; these levels remained stable after 3 months of dialysis with polysulfone. Complement activation and neutropenia during dialysis were significantly more marked with cuprammonium, but were not affected by reprocessing of either dialyzer. In vitro adsorption of 124I-beta 2M to polysulfone fibers was greater than to cuprammonium; adsorption was not influenced by dialyzer reprocessing.

  9. Comparison of CCD astrolabe multi-site solar diameter observations

    NASA Astrophysics Data System (ADS)

    Andrei, A. H.; Boscardin, S. C.; Chollet, F.; Delmas, C.; Golbasi, O.; Jilinski, E. G.; Kiliç, H.; Laclare, F.; Morand, F.; Penna, J. L.; Reis Neto, E.

    2004-11-01

    Results are presented of measured variations of the photospheric solar diameter, as concurrently observed at three sites of the R2S3 (Réseau de Suivi au Sol du Rayon Solaire) consortium in 2001. Important solar flux variations appeared in that year, just after the maximum of solar activity cycle 23, make that time stretch particularly promising for a comparison of the multi-site results. The sites are those in Turkey, France and Brasil. All observations are made with similar CCD solar astrolabes, and at nearby effective wavelengths. The data reductions share algorithms, that are alike, the outcomes of which are here treated after applying a normalization correction using the Fried parameter. Since the sites are geographically quite far, atmospheric conditions are dismissed as possible causes of the large common trend found. Owing to particularities of each site, the common continuous observational period extends from April to September. The standard deviation for the daily averages is close to 0.47 arcsec for the three sites. Accordingly, the three series are smoothed by a low-pass-band Fourier filter of 150 observations (typically one month). The main common features found are a declining linear trend, of the order of 0.7 mas/day, and a relative maximum, around MJD 2120, of the order of 100 mas. Standard statistical tests endorse the correlation of the three series.

  10. Structure of the Mesophases Formed by a Perfluoroalkyl/Biphenyl Compound. Amphiphilic and Steric Effects

    NASA Astrophysics Data System (ADS)

    Pensec, Sandrine; Tournilhac, François-Genès; Bassoul, Pierre

    1996-11-01

    We describe the synthesis and mesomorphic behaviour of 4-(1H,1H-perfluorooctyloxy)- 4'-methoxy biphenyl. Two mesophases of smectic E and smectic A types were observed. X-ray diffraction study of the smectic E phase indicates a herringbone arrangement of the biphenyl cores, the perfluoroalkyl chains being in a molten state. The {S_E to S_A} transition is related to the melting of the biphenyl sublattice. In both phases, the flexibility of perfluoroalkyl chains permits the area matching between the two segregated sublayers. Nous décrivons la synthèse et les propriétés mésomorphes du 4-(1H,1H-perfluorooctyloxy)- 4'-méthoxy biphényle. Ce composé forme deux mésophases de type smectique E et smectique A. L'analyse par diffraction des rayons X révèle, dans le cas de la phase smectique E un arrangement en chevrons des coeurs biphényles, les chaînes perfluoroalkyles se trouvant dans un état désordonné. La transition {S_E to S_A} correspond à la fusion partielle de la sous-couche biphényle. Dans les deux phases smectiques, la flexibilité des chaînes perfluoroalkyles permet l'adéquation des aires moléculaires entre les deux sous-couches ségrégées.

  11. The effect of green tea and olive oil on the mutagenic activity of heterocyclic amines extracted from common food consumed in Saudi Arabia.

    PubMed

    Awney, Hala

    2011-05-01

    The effect of green tea (GT) and green tea with olive oil (GT+OL) as antioxidants on the formation and mutagenic activity of heterocyclic aromatic amines (HCAs) extracted from beef shawerma, grilled chicken and fried beef liver was examined. HCAs were extracted by blue rayon, analyzed as spiked and unspiked samples with high-performance liquid chromatography and its mutagenic response was assessed by Sallmonela typhimurium 100 in the Ames test. Surprisingly, GT and GT+OL augmented HCAs measured in beef shawerma and grilled chicken but total HCAs measured in GT+OL were less than GT treatment. Both treatments altered the HCA profile as imidazoquinoline type became the most abundant. In control and GT+OL fried beef liver no HCAs were detected, but Trp-P1 was detected in GT treatment. Generally, the mutagenic response of HCAs measured in GT+OL was less than GT in beef shawerma and grilled chicken. However, the mutagenic response of control and 2% GT+OL fried liver was negative. These data suggest that GT concentrations used in this study may induce free radical formation during the Millared reaction due to its pro-oxidative effect, which augmented the HCAs formed and its mutagenic response. In order to optimize both safety and quality of our diets, more need to be done to fully understand the risk of HCAs in food.

  12. Apport des neutrons à l'analyse structurale des composés partiellement désordonnés

    NASA Astrophysics Data System (ADS)

    Cousson, A.

    2003-02-01

    La cristallographie est un outil extrêmement puissant qui pourrait être utilisé par de nombreux scientifiques dont les sujets de recherche sont en fait très éloignés. L'évolution des techniques ces dernières années a relégué par exemple la cristallographie des rayons X des petites molécules à un rôle mineur, un rôle de service. Certains ont même le sentiment semble-t-il que toutes les connaissances sont contenues dans de multiples logiciels capables par eux-mêmes de conduire une analyse structurale à un résultat correct unique. Il est souhaitable que chacun soit capable de réaliser l'étude structurale du composé qui l'intéresse et bien entendu nécessaire de comprendre ce que l'on fait, la qualité des résultats et leur analyse en dépend. L'objet de cette présentation est de montrer l'apport spécifique de la diffraction de neutrons sur monocristaux à l'étude du désordre, en particulier des atomes d'hydrogène, et ses conséquences sur la compréhension des propriétés physiques, à partir de développements et d'exemples récents.

  13. User experience analysis of e-TB Manager, a nationwide electronic tuberculosis recording and reporting system in Ukraine

    PubMed Central

    Sawyer, Kelly; Nizova, Nataliya

    2017-01-01

    Ukraine has successfully implemented e-TB Manager nationwide as its mandatory national tuberculosis registry after first introducing it in 2009. Our objective was to perform an end-of-programme evaluation after formal handover of the registry administration to Ukraine's Centre for Disease Control in 2015. We conducted a nationwide, cross-sectional, anonymous, 18-point user experience survey, and stratified the registry's transaction statistics to demonstrate usability. Contrary to initial implementation experience, older users (aged >50 years), often with limited or no computer proficiency prior to using the registry, had significantly better user experience scores for at least six of the 12 measures compared to younger users (aged 18–29 years). Using the registry for >3 years was associated with significantly higher scores for having capacity, adequacy of training received and satisfaction with the registry. Of the 5.9 million transactions over a 4-year period, nine out of 24 oblasts (regions) and Kiev city accounted for 62.5% of all transactions, and corresponded to 59% of Ukraine's tuberculosis burden. There were 437 unique active users in 486 rayons (districts) of Ukraine, demonstrating extensive reach. Our key findings complement the World Health Organization and European Respiratory Society's agenda for action on digital health to help implement the End TB Strategy. PMID:28512634

  14. Trapping of edge dislocations by a moving smectic-A smectic-B interface

    NASA Astrophysics Data System (ADS)

    Oswald, P.; Lejcek, L.

    1991-09-01

    We analyze how the motion of the edge dislocations of the smectic-A liquid crystal allows the system to relax plastically the stresses that are generated during the growth of the smectic-B plastic crystal. These stresses are both due, to the density difference between the two phases, and to the layer thickness variation at the phase transition. In particular, we calculate under which conditions a dislocation can be trapped by the smectic-B phase. Finally, we suggest that this dynamical trapping is responsible for the very large amount of stacking faults observed by X-ray diffraction. Nous analysons comment le mouvement des dislocations coin du cristal liquide smectique A permet de relaxer plastiquement les contraintes induites par la croissance du cristal plastique smectique B. Ces contraintes sont engendrées à la fois par la différence de densité qui existe entre les deux phases et par la variation d'épaisseur des couches à la transition. Nous calculons en particulier dans quelles conditions une dislocation coin peut être piégée par le smectique B. Enfin, nous suggérons que ce piégeage dynamique est à l'origine de la très forte densité de fautes d'empilement qui est couramment observée aux rayons X dans la phase B.

  15. Comparison of BioStar Strep A OIA optical immune assay, Abbott TestPack Plus Strep A, and culture with selective media for diagnosis of group A streptococcal pharyngitis.

    PubMed Central

    Roe, M; Kishiyama, C; Davidson, K; Schaefer, L; Todd, J

    1995-01-01

    We directly compared three techniques for the diagnosis of group A streptococcal pharyngitis in 500 symptomatic children seen in the Emergency Department or Child Care Clinic of The Children's Hospital of Denver. Throats were vigorously swabbed with two rayon swabs, which were transported immediately to the Microbiology Laboratory. Each swab was cultured aerobically on Strep A Isolation Agar (Remel) and then tested for antigen-one swab by the Strep A OIA optical immune assay (BioStar) and the other by the TestPack Plus Strep A (Abbott) technique. Each test was performed blind to the others. The refrigerated pledget was cultured in Todd-Hewitt broth if an antigen test was positive and both direct plate cultures were negative (the "gold standard" was any culture positive). All isolates were serologically grouped. Of 500 complete patient cultures, 151 (30%) were positive for group A streptococcal growth. The two antigen tests gave comparable results with an average sensitivity of 83%. Each was significantly (P < 0.02) less sensitive than its corresponding culture. The BioStar Strep A OIA optical immune assay produced significantly (P < 0.003) more false-positive results than did the Abbott test. Rapid antigen testing is not sensitive enough to eliminate the need for backup cultures. PMID:7650184

  16. Interprétation cohérente du coefficient de Poisson négatif rapporté dans des multicouches métalliques : rôle du paramètre libre de contrainte

    NASA Astrophysics Data System (ADS)

    Badawi, K. F.; Goudeau, Ph.; Durand, N.

    1998-04-01

    Elastic properties of multilayers with low period thickness show in some cases anomalies which are generally correlated with structural modifications in individual layers. In the recent past, several studies have evidenced using X-ray diffraction in-plane and out-of-plane strains with the same sign. Some authors have then proposed in the case of W/Ni and Nb/Cu metallic superlattices to use a negative Poisson's ratio. This result is surprising because the value of this coefficient in metals is generally positive. In this article, we introduce a novel interpretation mainly based on the experimental determination by sin^2Psi method of the reference parameter (stress-free lattice parameter) used in strain calculations. Then, we show that the introduction of the bulk parameter instead of stress-free parameter for the reference parameter is an unrealistic assumption in the case of thin films and multilayers (W and Ag/Ni) and may thus lead to wrong results which are then in total disagreement with those obtained by other techniques. Therefore, the elastic anomaly concerning Poisson's ratio which has been reported by some authors in scientific literature do not result from real structure of multilayers but from experimental X-ray diffraction data analysis. Les propriétés élastiques dans certains systèmes multicouches de faible période présentent des anomalies qui sont généralement associées à des modifications des propriétés structurales de chacune des couches. Ainsi, plusieurs études ont mis en évidence par diffraction des rayons X des déformations de même signe dans le plan et selon la normale au plan des couches déposées. Certains auteurs ont alors proposé dans le cas de systèmes métalliques W/Ni et Nb/Cu l'utilisation d'un coefficient de Poisson négatif. Ce résultat est surprenant car la valeur de ce coefficient pour les métaux est généralement positive. Dans cet article, nous présentons une nouvelle interprétation reposant sur la détermination expérimentale par la méthode des sin^2Psi de la référence (paramètre libre de contrainte) servant de base au calcul des déformations. Nous montrons alors que l'introduction du paramètre du matériau massif comme référence est une hypothèse irréaliste dans le cas des films minces et multicouches (W et Ag/Ni) qui peut conduire à des résultats erronés et en total désaccord avec ceux obtenus par d'autres techniques. Ainsi, l'anomalie élastique au niveau du coefficient de Poisson soulevée par certains auteurs dans la littérature n'est pas imputable à la structure elle-même mais à l'analyse qui est faite des données expérimentales obtenues par diffraction des rayons X.

  17. Microplastic pollution in sediments from the Bohai Sea and the Yellow Sea, China.

    PubMed

    Zhao, Jianmin; Ran, Wen; Teng, Jia; Liu, Yongliang; Liu, Hui; Yin, Xiaonan; Cao, Ruiwen; Wang, Qing

    2018-06-02

    Microplastics are one of the most significant pollutants in the marine environment and accumulate in sediments all over the world. To assess the pollution level in the marine environment in China, the distribution and abundance of microplastics in sediments from the Bohai Sea and the Yellow Sea were investigated in this study. The sediment samples were collected from 72 different sites in the Bohai Sea and the Yellow Sea. Microplastics were separated from sediment through density flotation and categorized according to shape and size under a microscope. Additionally, polymer types were identified using Fourier-Transform Infrared Micro-spectroscopy (μ-FT-IR). Our study demonstrated that microplastics were consistently found in all samples, which emphasized their extensive distribution throughout the Bohai Sea and the Yellow Sea. The average microplastic abundance was 171.8, 123.6 and 72.0 items per kg of dry weight sediment for the Bohai Sea, Northern Yellow Sea and Southern Yellow Sea, respectively. Among the sampled microplastics, fiber (93.88%) and small microplastics (<1000 μm) (71.06%) were the most frequent types. Fourier transform infrared microspectroscopy (μ-FT-IR) analysis determined that the main types of microplastics were rayon (RY), polyethylene (PE) and polyethylene terephthalate (PET). Our results highlighted the widespread distribution of microplastics in sediments from the Bohai Sea and the Yellow Sea and provided useful information for evaluating the environmental risks of microplastics in China. Copyright © 2018. Published by Elsevier B.V.

  18. Land Change in Russia since 2000

    NASA Astrophysics Data System (ADS)

    de Beurs, K.; Ioffe, G.; Nefedova, T.

    2010-12-01

    Agricultural reform has been an important anthropogenic change process shaping landscapes in European Russia since the formal collapse of the Soviet Union at the end of 1991. Widespread land abandonment is perhaps the most evident side effect of the reform, even visible in synoptic imagery. While land abandonment as a result of the collapse of the Soviet Union is relatively well documented, few studies have investigated the unfolding process of abandonment that results from rural population declines. Russia’s population is projected to shrink by a staggering 29% by 2050 and population dynamics are predicted to play a significant role structuring rural landscapes across European Russia. While often treated as a unified whole with respect to agricultural reform, significant regional diversity exists in Russia. Official statistics at the rayon (county) level are typically skewed toward large-scale farming and farm data from important household productions are summarized into regional averages. In addition, data at sub-district level can often only be obtained by visiting rural administrators in person. Large scale official data thus need to be interpreted with caution. Here we present data collected during the summer of 2010 from representative settlements and enterprises in selected counties within the oblasts (states) of Kostroma and Samara. These field data will provide an initial overview of the economic and social state in modern rural western Russia. We will combine the field data with established socio-demographic observations as well as satellite observations at multiple scales to understand the effect of global change and to project future developments.

  19. Coal desulfurization in a rotary kiln combustor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cobb, J.T. Jr.

    1991-04-22

    The focus of our work during the first quarter of 1991 was on combustion tests at the PEDCO rotary kiln reactor at North American Rayon (NARCO) plant in Elizabethton, TN. The tests had essentially tow related objectives: (a) to obtain basic data on the combustion of anthracite culm in a rotary kiln reactor, and (b) upon the test results, determine how best to proceed with our own planned program at the Humphrey Charcoal kiln in Brookville, PA. The rationale for the tests at PEDCO arose from process analysis which posted red flags on the feasibility of burning low-grade, hard-to-burn fuelsmore » like anthracite culms, in the rotary kiln. The PEDCO unit afforded a unique opportunity to obtain some quick answers at low cost. Two different anthracite culm fuels were tested: a so-called Jeddo culm with an average heating value of 7000 Btu/lb, and a relatively poorer culm, and Emerald'' culm, with an average heating value of 5000 Btu/lb. An attempt was also made to burn a blend of the Emerald culm with bituminous coal in 75/25 percent proportions. This report describes the tests, their chronology, and preliminary results. As it turned out, the PEDCO unit is not configured properly for the combustion of anthracite culm. As a result, it proved difficult to achieve a sustained period of steady-state combustion operation, and combustion efficiencies were low even when supplemental fuel was used to aid combustion of the culm. 1 fig., 2 tabs.« less

  20. X-ray Studies of Regenerated Cellulose Fibers Wet Spun from Cotton Linter Pulp in NaOH/Thiourea Aqueous Solutions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen,X.; Burger, C.; Fang, D.

    Regenerated cellulose fibers were fabricated by dissolution of cotton linter pulp in NaOH (9.5 wt%) and thiourea (4.5 wt%) aqueous solution followed by wet-spinning and multi-roller drawing. The multi-roller drawing process involved three stages: coagulation (I), coagulation (II) and post-treatment (III). The crystalline structure and morphology of regenerated cellulose fiber was investigated by synchrotron wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) techniques. Results indicated that only the cellulose II crystal structure was found in regenerated cellulose fibers, proving that the cellulose crystals were completely transformed from cellulose I to II structure during spinning from NaOH/thiourea aqueous solution. Themore » crystallinity, orientation and crystal size at each stage were determined from the WAXD analysis. Drawing of cellulose fibers in the coagulation (II) bath (H{sub 2}SO{sub 4}/H{sub 2}O) was found to generate higher orientation and crystallinity than drawing in the post-treatment (III). Although the post-treatment process also increased crystal orientation, it led to a decrease in crystallinity with notable reduction in the anisotropic fraction. Compared with commercial rayon fibers fabricated by the viscose process, the regenerated cellulose fibers exhibited higher crystallinity but lower crystal orientation. SAXS results revealed a clear scattering maximum along the meridian direction in all regenerated cellulose fibers, indicating the formation of lamellar structure during spinning.« less

  1. La biogenèse des mélanosomes

    PubMed Central

    Delevoye, Cédric; Giordano, Francesca; van Niel, Guillaume; Raposo, Graça

    2012-01-01

    Les mélanocytes situés à la base de l’épiderme produisent des mélanosomes qui sont transférés aux kératinocytes pour assurer la pigmentation de l’épiderme et sa photoprotection contre les rayons ultraviolets. Les mélanosomes, organites apparentés aux lysosomes, sont le lieu de synthèse et de stockage d’un pigment, la mélanine. Leur formation dépend de protéines mélanosomales qui transitent par les voies de biosynthèse et d’endocytose et exploitent les mécanismes moléculaires du trafic intracellulaire. Les acteurs moléculaires impliqués dans le transport des protéines mélanosomales et la biogenèse des mélanosomes sont la cible de mutations dans des maladies génétiques accompagnées d’hypopigmentation comme l’albinisme et les maladies lysosomales. Les études menées sur les mélanocytes issus de souris modèles de ces maladies permettent de comprendre certaines des étapes-clés de la mélanogenèse ainsi que les dysfonctionnements associés à ces pathologies. De plus, décrypter la mélanogenèse facilite également la compréhension d’autres processus physiologiques, comme l’illustrent les similitudes inattendues avec l’amyloïdogenèse dans les maladies neurodégénératives. PMID:21382323

  2. Twisted nematic liquid crystal cells with rubbed poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) films for active polarization control of terahertz waves

    NASA Astrophysics Data System (ADS)

    Sasaki, Tomoyuki; Okuyama, Hiroki; Sakamoto, Moritsugu; Noda, Kohei; Okamoto, Hiroyuki; Kawatsuki, Nobuhiro; Ono, Hiroshi

    2017-04-01

    We fabricated a terahertz (THz) polarization converter using a twisted nematic (TN) liquid crystal (LC) cell. Poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) films coated on quartz glass substrates were used as electrode layers in the TN LC cell. The PEDOT/PSS films were rubbed unidirectionally using a rayon cloth to align the nematic LC, thereby also serving as an alignment layer. The azimuthal surface anchoring strength of the PEDOT/PSS films was measured to be 5 × 10-4 J/m2 using the Néel wall method, which is similar to that of typical polymeric alignment layers. The optical constants of the PEDOT/PSS film in the THz range were also characterized using the Drude-Smith model, and the results indicated that the PEDOT/PSS films could be used both as transparent electrodes in the THz range and as alignment layers for the LC. The electro-optical properties of the fabricated TN LC cell were also investigated using a polarized visible laser and THz time-domain spectroscopic system. In particular, the transmission spectra and polarization conversion property of the TN LC cell in the THz range were theoretically analyzed based on a stratified model that considers optical anisotropy, absorption, and multiple interference. This work substantiates the advantages of TN LC cells with rubbed PEDOT/PSS films useful for THz polarization converters with electrical tunability.

  3. Heterocyclic amines content of meat and fish cooked by Brazilian methods.

    PubMed

    Iwasaki, Motoki; Kataoka, Hiroyuki; Ishihara, Junko; Takachi, Ribeka; Hamada, Gerson Shigeaki; Sharma, Sangita; Le Marchand, Loïc; Tsugane, Shoichiro

    2010-02-01

    Heterocyclic amine (HCA) concentrations were measured in meat and fish samples cooked by pan-frying, grilling and churrasco (Brazilian barbecue) to various levels of doneness in accordance with the cooking methods most commonly used in Brazil. HCAs were extracted by the Blue-rayon absorption method and measured by liquid chromatography-mass spectrometry. 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), and 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx) were sharply increased in very well-done meats and fish. HCA levels varied somewhat across cooking methods: levels of PhIP (ng/g) in very well-done, non-marinated samples were particularly high for churrasco (31.8 in the exterior of the sample), compared to lower levels for grilled (16.3), and pan-fried beef (0.58). On comparison across foods, chicken contained higher HCA levels than other non-marinated samples. For example, PhIP levels (ng/g) in very well-done pan-fried foods were 34.6 for chicken with the skin, 0.58 for beef, 7.25 for pork, 2.28 for sardines, and 7.37 for salmon cooked with the skin. HCA levels were lower in marinated meats and fish than in non-marinated samples, except for pan-fried salmon. This study provides valuable information which will allow the estimation of dietary HCA exposure using an epidemiologic questionnaire and the investigation of the association of HCA intake with cancer risk in Brazil.

  4. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Milbrandt, Anelia; Booth, Samuel

    Carbon fiber (CF), known also as graphite fiber, is a lightweight, strong, and flexible material used in both structural (load-bearing) and non-structural applications (e.g., thermal insulation). The high cost of precursors (the starting material used to make CF, which comes predominately from fossil sources) and manufacturing have kept CF a niche market with applications limited mostly to high-performance structural materials (e.g., aerospace). Alternative precursors to reduce CF cost and dependence on fossil sources have been investigated over the years, including biomass-derived precursors such as rayon, lignin, glycerol, and lignocellulosic sugars. The purpose of this study is to provide a comprehensivemore » overview of CF precursors from biomass and their market potential. We examine the potential CF production from these precursors, the state of technology and applications, and the production cost (when data are available). We discuss their advantages and limitations. We also discuss the physical properties of biomass-based CF, and we compare them to those of polyacrylonitrile (PAN)-based CF. We also discuss manufacturing and end-product considerations for bio-based CF, as well as considerations for plant siting and biomass feedstock logistics, feedstock competition, and risk mitigation strategies. The main contribution of this study is that it provides detailed technical and market information about each bio-based CF precursor in one document while other studies focus on one precursor at a time or a particular topic (e.g., processing). Thus, this publication allows for a comprehensive view of the CF potential from all biomass sources and serves as a reference for both novice and experienced professionals interested in CF production from alternative sources.« less

  5. Swab Protocol for Rapid Laboratory Diagnosis of Cutaneous Anthrax

    PubMed Central

    Marston, Chung K.; Bhullar, Vinod; Baker, Daniel; Rahman, Mahmudur; Hossain, M. Jahangir; Chakraborty, Apurba; Khan, Salah Uddin; Hoffmaster, Alex R.

    2012-01-01

    The clinical laboratory diagnosis of cutaneous anthrax is generally established by conventional microbiological methods, such as culture and directly straining smears of clinical specimens. However, these methods rely on recovery of viable Bacillus anthracis cells from swabs of cutaneous lesions and often yield negative results. This study developed a rapid protocol for detection of B. anthracis on clinical swabs. Three types of swabs, flocked-nylon, rayon, and polyester, were evaluated by 3 extraction methods, the swab extraction tube system (SETS), sonication, and vortex. Swabs were spiked with virulent B. anthracis cells, and the methods were compared for their efficiency over time by culture and real-time PCR. Viability testing indicated that the SETS yielded greater recovery of B. anthracis from 1-day-old swabs; however, reduced viability was consistent for the 3 extraction methods after 7 days and nonviability was consistent by 28 days. Real-time PCR analysis showed that the PCR amplification was not impacted by time for any swab extraction method and that the SETS method provided the lowest limit of detection. When evaluated using lesion swabs from cutaneous anthrax outbreaks, the SETS yielded culture-negative, PCR-positive results. This study demonstrated that swab extraction methods differ in their efficiency of recovery of viable B. anthracis cells. Furthermore, the results indicated that culture is not reliable for isolation of B. anthracis from swabs at ≥7 days. Thus, we recommend the use of the SETS method with subsequent testing by culture and real-time PCR for diagnosis of cutaneous anthrax from clinical swabs of cutaneous lesions. PMID:23035192

  6. Online in situ x-ray diffraction setup for structural modification studies during swift heavy ion irradiation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Grygiel, C.; Lebius, H.; Bouffard, S.

    2012-01-15

    The high energy density of electronic excitations due to the impact of swift heavy ions can induce structural modifications in materials. We present an x-ray diffractometer called ALIX (''Analyse en Ligne sur IRRSUD par diffraction de rayons X''), which has been set up at the low-energy beamline (IRRadiation SUD - IRRSUD) of the Grand Accelerateur National d'Ions Lourds facility, to allow the study of structural modification kinetics as a function of the ion fluence. The x-ray setup has been modified and optimized to enable irradiation by swift heavy ions simultaneously to x-ray pattern recording. We present the capability of ALIXmore » to perform simultaneous irradiation-diffraction by using energy discrimination between x-rays from diffraction and from ion-target interaction. To illustrate its potential, results of sequential or simultaneous irradiation-diffraction are presented in this article to show radiation effects on the structural properties of ceramics. Phase transition kinetics have been studied during xenon ion irradiation of polycrystalline MgO and SrTiO{sub 3}. We have observed that MgO oxide is radiation-resistant to high electronic excitations, contrary to the high sensitivity of SrTiO{sub 3}, which exhibits transition from the crystalline to the amorphous state during irradiation. By interpreting the amorphization kinetics of SrTiO{sub 3}, defect overlapping models are discussed as well as latent track characteristics. Together with a transmission electron microscopy study, we conclude that a single impact model describes the phase transition mechanism.« less

  7. Effect of cloacal plugging on microbial recovery from partially processed broilers.

    PubMed

    Musgrove, M T; Cason, J A; Fletcher, D L; Stern, N J; Cox, N A; Bailey, J S

    1997-03-01

    Experiments were performed to test the contribution of bacteria contained in the intestinal tract of broilers at the beginning of processing to counts on the exterior of modified New York-dressed carcasses. Thirty-two birds were processed for each of seven replications. Within each replication, batches of four birds were electrocuted, scalded, and picked, with batches alternating between treatment and control groups. Treated birds were cloacally plugged with rayon fiber tampons prior to electrocution to prevent escape of intestinal contents during scalding and picking. Control birds were processed in the same manner, except that cloacal plugs were inserted immediately after defeathering to reduce escape of intestinal contents during sampling. Gram-negative enteric bacteria and Campylobacter spp. were enumerated on carcasses by whole carcass rinse procedure and in cecal contents. Counts were converted to log10 and subjected to analysis of variance. Cecal levels of Gram-negative enterics were significantly higher for plugged birds, but there was not a significant difference between levels of cecal Campylobacter spp. between treatment groups. Plugging before electrocution resulted in significantly lower levels (2.5 vs 3.0 log10 cfu/mL) of Campylobacter spp. and Gram-negative enteric bacteria (3.0 vs 3.4 log10 cfu/mL) in carcass rinses of treatment birds than in those of controls. All carcasses were positive for Gram-negative enterics. Cloacal plugging resulted in significantly lower incidence of Campylobacter spp. carcass contamination as determined by chi-square. Intestinal carriage of both campylobacters and Gram-negative enteric bacteria appears to influence the microbial quality of the carcass during processing.

  8. L'effet des deformations plastiques severes sur les proprietes d'hydruration du magnesium

    NASA Astrophysics Data System (ADS)

    Lang, Julien

    Le travail de recherche effectue durant mon projet de maitrise en physique a l'Universite du Quebec a Trois-Rivieres dans les laboratoires de l'Institut de Recherche sur l'Hydrogene etait de comparer l'effet du laminage a froid de la poudre de MgH2 avec celui du broyage mecanique. Nous avons etudie cette nouvelle technique en utilisant un laminoir vertical concu specialement pour laminer de la poudre. Nous avons lamine la poudre de MgH2 5, 25, 50 et 100 fois. La comparaison de la morphologie de la poudre de MgH 2 telle que recu du manufacturier et broye mecaniquement pendant 30 minutes avec celle de la poudre laminee ete faite a l'aide d'un microscope electronique a balayage. Nous avons par la suite mesure les proprietes de sorption d'hydrogene grace un appareil PCT de type Sievert. Nous avons aussi determine la structure cristalline par diffraction de rayons X. A partir de ces resultats, nous avons constate que le nombre optimal de laminages est de cinq et a les caracteristiques d'absorption/desorption d'hydrogene similaires a un broyage mecanique de 30 minutes. Nous avons aussi utilise les courbes de cinetiques d'absorption et de desorption d'hydrogene pour calculer l'etape limitative dans les reactions de sorption des echantillons lamines. Comme cinq laminages se font en environ 10 secondes, on voit que le laminage a froid est une technique plus interessante industriellement que le broyage mecanique a cause de l'important gain en temps et en energie.

  9. Heterocyclic amines content of meat and fish cooked by Brazilian methods

    PubMed Central

    Iwasaki, Motoki; Kataoka, Hiroyuki; Ishihara, Junko; Takachi, Ribeka; Hamada, Gerson Shigeaki; Sharma, Sangita; Le Marchand, Loïc; Tsugane, Shoichiro

    2009-01-01

    Heterocyclic amine (HCA) concentrations were measured in meat and fish samples cooked by pan-frying, grilling and churrasco (Brazilian barbecue) to various levels of doneness in accordance with the cooking methods most commonly used in Brazil. HCAs were extracted by the Blue-rayon absorption method and measured by liquid chromatography–mass spectrometry. 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), and 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx) were sharply increased in very well-done meats and fish. HCA levels varied somewhat across cooking methods: levels of PhIP (ng/g) in very well-done, non-marinated samples were particularly high for churrasco (31.8 in the exterior of the sample), compared to lower levels for grilled (16.3), and pan-fried beef (0.58). On comparison across foods, chicken contained higher HCA levels than other non-marinated samples. For example, PhIP levels (ng/g) in very well-done pan-fried foods were 34.6 for chicken with the skin, 0.58 for beef, 7.25 for pork, 2.28 for sardines, and 7.37 for salmon cooked with the skin. HCA levels were lower in marinated meats and fish than in non-marinated samples, except for pan-fried salmon. This study provides valuable information which will allow the estimation of dietary HCA exposure using an epidemiologic questionnaire and the investigation of the association of HCA intake with cancer risk in Brazil. PMID:20383312

  10. Texture analysis of oxide dispersion strengthened (ODS) Fe alloys by X-ray and neutron diffraction

    NASA Astrophysics Data System (ADS)

    Béchade, J. L.; Mathon, M. H.; Branger, V.; Réglé, H.; Alamo, A.

    2002-07-01

    The ferritic ODS alloys studied were obtained by mechanical alloying. This strengthening method is very attractive, in particular for nuclear applications. In order to ensure the alloy a good compromise between mechanical resistance and ductility at high temperatures, it is necessary to control the microstructure and in particular the evolution during the recrystallization. First, a preliminary study, performed by X ray diffraction and optical microscopy, shows several grain growth mechanisms ; in particular, the “abnormal” grain growth mechanism which conducts to a large grain size [1], [2]. After annealing (3600s at 1470^{circ}C), the 30% cold-worked (swaging) alloys exhibit an heterogeneous microstructure with a large grains size ( 200 to 500 μm) in the heart and near the surface of the material when the intermediate zone is inhabited by small grains ( 1 μm). Fora higher cold-work level (60%), large size grains are only present in the periphery of the material. On account of the large grain size and strong heterogeneity of the microstructure, texture analysis using laboratory x-ray beam in not well adapted and so we have decided to use neutron beam. The neutron diffraction texture analysis has been performed at the Laboratoire Léon Brillouin on the 6T1 diffractometer on 2 different rods of the alloy (corresponding to the reduction ratios of 30% and 60%). Specific samples have been machined to characterise separately the zones with a different microstructure. After deformation, the alloys exhibit a typical α-fibre texture \\{ hkl \\} <1l0> whatever the area of the sample and the reduction ratio. After recrystallization, a very inhomogeneous texture is evidenced through the thickness of the sample, in particular for the rod deformed with a reduction ratio of 30% : in the heart and in the periphery of the rod, a “single-crystal” type texture is observed; the a fibre remains for the intermediate diameter of the rod. For the rod cold rolled with a reduction ratio of 60%, the α-fibre keeps on the heart of the material and as in the precedent case, a “single-crystal” type texture is observed near the surface of the sample. EBSD measurements have been performed to explicit at a local scale this behaviour and in order to furnish some input data for the simulation of static recrystallization. Les aciers ferritiques avec dispersion d'oxydes étudiés sont obtenus par métallurgie des poudres, ce qui leur confère une résistance mécanique accrue à haute température notamment pour des applications nucléaires. La difficulté pour l'utilisation de tels alliages réside dans la maîtrise de leur microstructure au cours de l'élaboration en particulier durant la recristallisation. Une première étude en diffraction des rayons-x et en métallographie optique a permis de révéler différents mécanismes de croissance du grain lors de la recristallisation, notamment une croissance “anormale” conduisant à une taille de grain très importante [t], [2]. Après recuit (3600s à 1470^{circ}C), précédé par un écrouissage de 30% sur des barres (par martelage) on voit apparaître une microstructure hétérogène à gros grains ( 200 à 500 μm) au coeur et en surface externe de la barre alors que la zone intermédiaire est peuplée de grains fins (sim 1 μm). Pour un écrouissage plus élevé (60%), après le même recuit, on ne voit apparaître des gros grains qu'en périphérie de la barre. Pour ce type de microstructure fortement hétérogène et à gros grains, la diffraction des rayons-x pour l'analyse de texture est mal adaptée, ce qui nous a conduit à utiliser la diffraction des neutrons sur le diffractomètre 6TI du Laboratoire Léon Brillouin. Les deux matériaux, écrouis de 30% et 60%, ont été analysés en réalisant des échantillons particuliers permettant d'étudier séparément le coeur et la périphérie. Après déformation, les deux échantillons présentent une texture de fibre α \\{ hkl \\} <1l0> en tout point de la barre. Après recristallisation, on retrouve une texture très hétérogène suivant le rayon de la barre, notamment après 30% : le coeur et la périphérie de la barre présentent une texture de type “mono-cristal”, la zone intermédiaire restant une fibre α. Après écrouissage de 60%, on garde la fibre α au coeur de la barre, la périphérie présentant, comme pour l'écrouissage précédent, une texture de type “mono-cristal”. Des analyses en EBSD ont également été réalisées pour foumir des éléments de compréhension sur les mécanismes locaux de recristallisation afin de simuler la recristallisation statique de ses alliages via une approche numérique.

  11. Microplastics in sediments of the Changjiang Estuary, China.

    PubMed

    Peng, Guyu; Zhu, Bangshang; Yang, Dongqi; Su, Lei; Shi, Huahong; Li, Daoji

    2017-06-01

    Microplastics are plastics that measure less than 5 mm in diameter. They enter the marine environment as primary sources directly from industrial uses, as well as secondary sources resulting from the degradation of large plastic debris. To improve the knowledge of microplastic pollution in China, we investigated samples from 53 estuarine sediment locations collected with a box corer within the Changjiang Estuary. Microplastics (<5 mm) were extracted from sediments by density separation, after which they were observed under a microscope and categorized according to shape, color and size. Identification was carried out using Micro-Fourier-Transform Infrared Spectroscopy (μ-FT-IR). The abundance of microplastics in the Changjiang Estuary was mapped. The mean concentration was 121 ± 9 items per kg of dry weight, varying from 20 to 340 items per kg of dry weight. It was found that the concentration of microplastics was the highest on the southeast coast of Shanghai. The distribution pattern of microplastics may be affected by the Changjiang diluted water in summer. All of the microplastics collected were categorized according to shape, color and size. Among which fiber (93%), transparent (42%) and small microplastics (<1 mm) (58%) were the most abundant types. No clear correlation between microplastics and the finer sediment fraction was found. Rayon, polyester, and acrylic were the most abundant types of microplastics identified, indicating that the main source of microplastics in the Changjiang Estuary was from washing clothes (the primary source). It is possible to compare microplastic abundance in this study with the results of other related studies using the same quantification method. The identification of microplastics raises the awareness of microplastic pollution from drainage systems. The prevalence of microplastic pollution calls for monitoring microplastics at a national scale on a regular basis. Copyright © 2016. Published by Elsevier Ltd.

  12. A high resolution Passive Flux Meter approach based on colorimetric responses

    NASA Astrophysics Data System (ADS)

    Chardi, K.; Dombrowski, K.; Cho, J.; Hatfield, K.; Newman, M.; Annable, M. D.

    2016-12-01

    Subsurface water and contaminant mass flux measurements are critical in determining risk, optimizing remediation strategies, and monitoring contaminant attenuation. The standard Passive Flux Meter, hereafter knows as a (PFM), is a well-developed device used for determining and monitoring rates of groundwater and contaminant mass flux in screened wells. The current PFM is a permeable device that contains granular activated carbon impregnated with alcohol tracers which is deployed in a flow field for a designated period of time. Once extracted, sampling requires laboratory analysis to quantify Darcy flux, which can be time consuming and have significant cost. To expedite test results, a modified PFM based on the image analysis of colorimetric responses, herein referred to as a colorimetric Passive Flux Meter (cPFM), was developed. Various dyes and sorbents were selected and evaluated to determine colorimetric response to water flow. Rhodamine, fluorescent yellow, fluorescent orange, and turmeric were the dye candidates while 100% wool and a 35% wool blend with 65% rayon were the sorbent candidates selected for use in the cPFM. Ultraviolet light image analysis was used to calculate average color intensity using ImageJ, a Java-based image processing program. These results were then used to quantify Darcy flux. Error ranges evaluated for Darcy flux using the cPFM are comparable to those with the standard, activated carbon based, PFM. The cPFM has the potential to accomplish the goal of obtaining high resolution Darcy flux data while eliminating high costs and analysis time. Implications of groundwater characteristics, such as PH and contaminant concentrations, on image analysis are to be tested through laboratory analysis followed by field testing of the cPFM.

  13. Slit lamps and lenses: a potential source of nosocomial infections?

    PubMed

    Sobolewska, Bianka; Buhl, Michael; Liese, Jan; Ziemssen, Focke

    2018-01-30

    The aim of the study was to evaluate the bacterial contamination level of contact surfaces on slit lamps and the grip areas of lenses. Within unannounced audits, two regions of the slit lamps (headrest and joystick), indirect ophthalmoscopy devices, and ultrasound probes were obtained with rayon-tipped swab. Non-contact lenses used for indirect fundoscopy were pressed on RODAC (Replicate Organism Detection and Counting) plates. One hundred and eighty-one surfaces were sampled. The total number of colony-forming units was assessed and bacterial species were identified. Spa-typing and antimicrobial susceptibility testing were performed from Staphylococcus aureus isolates. Among the total bacterial isolates from ophthalmological equipment (lenses: 51 of 78, slit lamps: 43 of 88, ophthalmoscopy helmets: 3 of 8, ultrasound probes: 2 of 7), coagulase-negative staphylococci (CNS) was most frequently found, followed by Micrococcus spp. (lenses vs. slit lamps: P < 0.001 and P = 0.01, respectively). The bacterial contamination of lenses (76%) was significantly higher than that of slit lamps (54%) (P < 0.003). A significantly higher contamination with CNS was observed on lenses from residents vs. from consultants (78% vs. 35%, P = 0.01). A total of seven different spa-types of S. aureus were isolated. No correlation was found between S. aureus contamination of different ophthalmological equipments (Spearman's rank correlation coefficient, ρ = 0.04, P = 0.75). Methicillin-resistant S. aureus was not detected. Bacterial species of the normal skin flora were isolated from the ophthalmological equipment. The bacterial contamination of the portable devices was significantly higher than that of slit lamps. Therefore, proper hygiene of the mobile instruments should be monitored in order to prevent transmission of bacteria in residents and consultants.

  14. Using mini-rockwool blocks as growing media for limited-cluster tomato production

    NASA Technical Reports Server (NTRS)

    Logendra, L. S.; Gianfagna, T. J.; Janes, H. W.

    2001-01-01

    Rockwool is an excellent growing medium for the hydroponic production of tomato; however, the standard size rockwool blocks [4 x 4 x 2.5 inches (10 x 10 x 6.3 cm) or 3 x 3 x 2.5 inches (7.5 x 7.5 x 6.3 cm)] are expensive. The following experiments were conducted with less expensive minirock wool blocks (MRBs), on rayon polyester material (RPM) as a bench top liner, to reduce the production cost of tomatoes (Lycopersicon esculentum) grown in a limited-cluster, ebb and flood hydroponic cultivation system. Fruit yield for single-cluster plants growing in MRBs [2 x 2 x 1.6 inches (5 x 5 x 4 cm) and 1.6 x 1.6 x 1.6 inches (4 x 4 x 4 cm)] was not significantly different from plants grown in larger sized blocks (3 x 3 x 2.5 inches). When the bench top was lined with RPM, roots penetrated the RPM, and an extensive root mat developed between the RPM and the bench top. The fruit yield from plants on RPM was significantly increased compared to plants without RPM due to increases in fruit size and fruit number. RPM also significantly reduced the incidence of blossom-end rot. In a second experiment, single- and double-cluster plants were grown on RPM. Fruit yield for double-cluster plants was 40% greater than for single-cluster plants due to an increase in fruit number, although the fruit were smaller in size. As in the first experiment, fruit yield for all plants grown in MRBs was not significantly different from plants grown in the larger sized blocks. MRBs and a RPM bench liner are an effective combination in the production of limited-cluster hydroponic tomatoes.

  15. TGBA and TGBC phases in some chiral tolan derivatives

    NASA Astrophysics Data System (ADS)

    Nguyen, H. T.; Bouchta, A.; Navailles, L.; Barois, P.; Isaert, N.; Twieg, R. J.; Maaroufi, A.; Destrade, C.

    1992-10-01

    Three chiral compounds (n=10, 11, 12) belonging to the optically active series : 3-fluoro-4-[(R) or (S)-1-methylheptyloxy]-4'-(4''-alkoxy-2'', 3''-difluorobenzoyloxy) tolans (nF{2}BTFO{1}M{7}) have been synthesized. The helical SA^{*} phase or TGBA phase is found in the decyloxy derivative. The most interesting compound is obtained with n=11. It displays, for the first time, two TGB phases (TGBA and TGBC phases). The nature of these helical smectic phases is confirmed by different studies : optical observation, DSC, contact method, mixtures, X-ray diffraction and helical pitch measurements. the electrooptical properties of the SC^{*} phase have also been studied. Trois produits (n=10, 11, 12) de la série chirale : 3-fluoro-4-[(R) ou (S)-1-methylheptyloxy]-4'-(4''-alcoxy-2'', 3''-difluorobenzoyloxy) tolanes (nF{2}BTFO{1}M{7}) ont été synthétisés. Les deux premiers produits présentent la phase SA^{*} hélicoïdale ou torse (TGBA). L'existence de la nouvelle phase TGBC, prédite par Renn et Lubensky, a été trouvée dans les deux derniers matériaux et prouvée par plusieurs études : observation microscopique, AED, méthode de contact, mélanges binaires, diffraction de rayons X et mesures du pas d'hélice. Le diagramme de phase réalisé entre ces trois matériaux est similaire à celui prédit par Renn. Les propriétés électrooptiques de la phase SC^{*} ferroélectrique ont aussi été étudiées.

  16. Evaluation of a New Environmental Sampling Protocol for Detection of Human Norovirus on Inanimate Surfaces

    PubMed Central

    Lee, David; Treffiletti, Aimee; Hrsak, Mario; Shugart, Jill; Vinjé, Jan

    2015-01-01

    Inanimate surfaces are regarded as key vehicles for the spread of human norovirus during outbreaks. ISO method 15216 involves the use of cotton swabs for environmental sampling from food surfaces and fomites for the detection of norovirus genogroup I (GI) and GII. We evaluated the effects of the virus drying time (1, 8, 24, or 48 h), swab material (cotton, polyester, rayon, macrofoam, or an antistatic wipe), surface (stainless steel or a toilet seat), and area of the swabbed surface (25.8 cm2 to 645.0 cm2) on the recovery of human norovirus. Macrofoam swabs produced the highest rate of recovery of norovirus from surfaces as large as 645 cm2. The rates of recovery ranged from 2.2 to 36.0% for virus seeded on stainless-steel coupons (645.0 cm2) to 1.2 to 33.6% for toilet seat surfaces (700 cm2), with detection limits of 3.5 log10 and 4.0 log10 RNA copies. We used macrofoam swabs to collect environmental samples from several case cabins and common areas of a cruise ship where passengers had reported viral gastroenteritis symptoms. Seventeen (18.5%) of 92 samples tested positive for norovirus GII, and 4 samples could be sequenced and had identical GII.1 sequences. The viral loads of the swab samples from the cabins of the sick passengers ranged from 80 to 31,217 RNA copies, compared with 16 to 113 RNA copies for swab samples from public spaces. In conclusion, our swab protocol for norovirus may be a useful tool for outbreak investigations when no clinical samples are available to confirm the etiology. PMID:26116675

  17. Nucléation et croissance de films YBa_{2Cu3O_{7 - δ}} déposés par ablation laser sur substrat de MgO(001)

    NASA Astrophysics Data System (ADS)

    Keller, D.; Gervais, A.; Chambonnet, D.; Belouet, C.; Audry, C.

    1995-02-01

    In the field of superconducting devices devoted to microwave applications, the crystalline texture of high quality thin films based on YBa{2}Cu{3}O{7 - δ} is of primary importance. This study presents the formation of this texture on MgO substrates with the nucleation and growth steps up to a film thickness of 300 nm as observed by means of AFM, HRTEM and XRD. The influence of deposition temperature on the growth mode is shown and a nucleation/growth model is discussed. The minimum roughness of c_{bot 0}{(^1)} textured films, 300 nm thick and 20 × 20 mm2 in size is as slow as 2 nm. Dans le cadre de la réalisation de composants supraconducteurs de haute qualité à base du composé YBa{2}Cu{3}O{7 - δ} destinés aux applications en hyperfréquences, le contrôle de la texture cristalline des films est de première importance. La formation de celle-ci sur substrat MgO est étudiée depuis la nucléation jusqu'à une épaisseur de 300 nm au moyen de la microscopie à force atomique, de la microscopie électronique en transmission à haute résolution et de la diffraction des rayons X. L'influence de la température de dépôt sur le mode de croissance est abordée et un modèle de nucléation/croissance est discuté. La rugosité minimale des films d'épaisseur 300 nm et de dimensions 20 × 20 mm2 de texture c_{bot 0}{(^1)} est voisine de 2 nm.

  18. Commerce de detail de l'essence automobile: Modelisation de l'impact a court terme des facteurs endogenes et exogenes sur les ventes d'essence dans les stations-service a Montreal

    NASA Astrophysics Data System (ADS)

    Nguimbus, Raphael

    La determination de l'impact des facteurs sous controle et hors controle qui influencent les volumes de vente des magasins de detail qui vendent des produits homogenes et fortement substituables constitue le coeur de cette these. Il s'agit d'estimer un ensemble de coefficients stables et asymtotiquement efficaces non correles avec les effets specifiques aleatoires des sites d'essence dans le marche de Montreal (Quebec, Canada) durant is periode 1993--1997. Le modele econometrique qui est ainsi specifie et teste, isole un ensemble de quatre variables dont le prix de detail affiche dans un site d'essence ordinaire, la capacite de service du site pendant les heures de pointe, les heures de service et le nombre de sites concurrents au voisinage du site dans un rayon de deux kilometres. Ces quatre facteurs influencent les ventes d'essence dans les stations-service. Les donnees en panel avec les methodes d'estimation robustes (estimateur a distance minimale) sont utilisees pour estimer les parametres du modele de vente. Nous partons avec l'hypothese generale selon laquelle il se developpe une force d'attraction qui attire les clients automobilistes dans chaque site, et qui lui permet de realiser les ventes. Cette capacite d'attraction varie d'un site a un autre et cela est du a la combinaison de l'effort marketing et de l'environnement concurrentiel autour du site. Les notions de voisinage et de concurrence spatiale expliquent les comportements des decideurs qui gerent les sites. Le but de cette these est de developper un outil d'aide a la decision (modele analytique) pour permettre aux gestionnaires des chaines de stations-service d'affecter efficacement les ressources commerciales dans ies points de vente.

  19. Étalement d'une goutte stratifiée incompressible

    NASA Astrophysics Data System (ADS)

    de Gennes, Pierre-Gilles; Cazabat, Anne-Marie

    L'étalement de films ultraminces de liquides simples sur une surface lisse horizontale conduit souvent à des gouttes à gradins d'une épaisseur moléculaire ([1]-[3]). Nous construisons ici un modèle pour la dynamique de l'étalement, en supposant que : (a) chaque gradin est un liquide bidimensionnel incompressible; (b) les molécules de la n-ième couche sont soumises à un potentiel (Wn) qui exprime leurs interactions à longue portée avec le solide; (c) on a un écoulement parallèle de cisaillement, et un écoulement normal de perméation. La perméation intervient seulement dans un certain « ruban » de largeur ξ sur le bord de chaque gradin. Dans le cas usuel, où le rayon du n-ième gradin Rn est trs supérieur à ξ, la dissipation est dominée par le cisaillement, et on arrive à des lois simples pour la vitesse de dilatation (ou de contraction) dotR_n. Very thin films of simple liquids often spread with well defined steps of molecular thickness ([1]-[3]). We construct a model for the dynamics of spreading assuming that: (a) each layer is an incompressible, 2 dimensional fluid; (b) the molecules in the (nth) layer experience a long range potential (e.g. Van der Waals) from the solid; (c) two types of flow occur: shear between layers and permeation normal to the layers. We find that permeation is important only in an annulus of small size ξ near each step. Between steps, the viscous effects in simple shear dominate, and this leads to simple laws for the dilation (or contraction) of the various layers.

  20. Dynamique d'étalement

    NASA Astrophysics Data System (ADS)

    de Gennes, Pierre-Gilles

    On analyse la progression d'un coin fiuide sur uo solide (dans le cas ou Tangle de contact thermodynamique θa est nul : regie d'Antonov satisfaite) en tenant compte des interactions Van der Waals a longue portee. On trouve : (a) un angle de contact apparent θa relie a la vitesse d'avancee U par θ^{3}_{a} ˜ U η/γ (η = viscosity, γ tension superficielle du liquide) d'ou une loi rayon/temps d'etalement pour une goutte r(t) 1/10. (b) un film precurseur ζ d'epaisseur ζ(x, f) decroissant asymptotiquement comme x1 ou x est la distance a la ligne triple. L'epaisseur h* d u film au voisinage de la ligne triple est h* a/θa (ou a est une distance atomique). Ceci permet de comprendre le fait (reconnu) que le film precurseur est bien visible seulement si l'angle de contact thermodynamique est nul. We analyse the shape of the liquid-air interface for a droplet spreading on a solid, in a regime where the Antonov rule is satisfied, taking into account the long range Van der Waals interactions between liquid and solid. We find: (a) an apparent contact angle θa related to the velocity U of the triple line by θ^{3}_{a} ˜ U η/γ (η = viscosity, γ surface tension of the liquid). This leads to a law of spreading (radius r/time t) for a droplet r t1/10. (b) a precursor film of thickness ζ, decreasing asymptotically like x-1, where x is the distance from the triple line. The thickness h* of the film at this line is h* a/θa where a is an atomic length: this explains why the precursor films are observed only when the thermodynamic contact angle vanishes.

  1. The distribution of chlorpyrifos following a crack and crevice type application in the US EPA Indoor Air Quality Research House

    NASA Astrophysics Data System (ADS)

    Stout, D. M.; Mason, M. A.

    A study was conducted in the US EPA Indoor Air Quality (IAQ) Research House to determine the spatial and temporal distribution of chlorpyrifos following a professional crack and crevice application in the kitchen. Following the application, measurements were made in the kitchen, den and master bedroom over 21 days. Airborne concentrations were collected using both polyurethane foam (PUF) and the OSHA versatile sampler composed of XAD and PUF media located in tandem. Measured airborne concentrations were similar for the two samplers and were higher in the three rooms following the application. The highest measured concentrations were reached during the initial 24-h following application; concentrations subsequently declined over the 21-day study period to levels slightly above background. Spatial and temporal distributions onto surfaces were measured using 10-cm 2 rayon deposition coupons located on the floor. Sections were cut from existing carpet to determine the total extractable residues. Chlorpyrifos was measured from all matrixes in the kitchen, den and bedroom and the data shows the transport of airborne residues from the point of application to remote locations in the house. The findings are compared and discussed relative to another study conducted in which total release aerosols containing chlorpyrifos were activated in the IAQ research house and the resulting distributions evaluated. For both studies dose estimates were constructed for the exposure pathways using the Stochastic Human Exposure and Dose Estimation Model for pesticides. The United States Environmental Protection Agency has been mandated to examine children's exposure to environmental pollutants such as pesticides. This research specifically reduces uncertainties associated with estimating children's potential exposures to residentially applied pesticides and provides inputs to further evaluate and validate residential exposure models which might be used to reduce exposures and perform risk assessments.

  2. On a phase transformation produced by mechanical activation in iron pyrite

    NASA Astrophysics Data System (ADS)

    Eymery, J.-P.

    1999-02-01

    The behaviour of pyrite in the process of mechanical milling in air has been examined. Milled powders were characterized by scanning electron microscopy, Mössbauer spectroscopy working in transmission geometry and X-ray diffraction. In the presence of oxygen, pyrite can readily be transformed to ferrous sulphate monohydrate, which indicates that the Fe(II) goes from a low-spin state to to a high-spin state. The transformation mechanism is saturated after about 60hours milling, but however it can be markedly prolonged by further ageing at room temperature. The results also indicate that mechanical milling is a useful room temperature process of material production. On a étudié le comportement de la pyrite au cours de broyages mécaniques réalisés à l'air. Les poudres broyées ont été analysées par microscopie électronique à balayage, spectroscopie Mössbauer fonctionnant en géométrie de transmission et diffraction des rayonsX. En présence d'oxygène, la pyrite se transforme immédiatement en sulfate de fer monohydraté, ce qui correspond pour Fe(II) au passage de l'état bas spin à l'état haut spin. Le mécanisme de la transformation est saturé après 60heures de broyage environ, mais cependant il peut être notablement prolongé par un vieillissement ultérieur à la température ambiante. Les résultats montrent aussi que le broyage mécanique constitue un processus utile de fabrication des matériaux à l'ambiante.

  3. Enrichment isolation of adipose-derived stem/stromal cells from the liquid portion of liposuction aspirates with the use of an adherent column.

    PubMed

    Doi, Kentaro; Kuno, Shinichiro; Kobayashi, Akira; Hamabuchi, Takahisa; Kato, Harunosuke; Kinoshita, Kahori; Eto, Hitomi; Aoi, Noriyuki; Yoshimura, Kotaro

    2014-03-01

    Adipose-derived stem/progenitor cells (ASCs) are typically obtained from the lipoaspirates; however, a smaller number of ASCs can be isolated without enzymatic digestion from the infranatant liposuction aspirate fluid (LAF). We evaluated the effectiveness of an adherent column, currently used to isolate mesenchymal stromal cells from bone marrow, to isolate LAF cells. We applied peripheral blood (PB), PB mixed with cultured ASCs (PB-ASC), and LAF solution to the column and divided it into two fractions, the adherent (positive) and the non-adherent (negative) fractions. We compared this method with hypotonic hemolysis (lysis) for the red blood cell count, nucleated cells count and cell compositions as well as functional properties of isolated mesenchymal cells. The column effectively removed red blood cells, though the removal efficiency was slightly inferior to hemolysis. After column processing of PB-ASC, 60.5% of ASCs (53.2% by lysis) were selectively collected in the positive fraction, and the negative fraction contained almost no ASCs. After processing of LAF solution, nucleated cell yields were comparable between the column and hemolysis; however, subsequent adherent culture indicated that a higher average ASC yield was obtained from the column-positive samples than from the lysis samples, suggesting that the column method may be superior to hemolysis for obtaining viable ASCs. Mesenchymal differentiation and network formation assays showed no statistical differences in ASC functions between the lysis and column-positive samples. Our results suggest that a column with non-woven rayon and polyethylene fabrics is useful for isolating stromal vascular fraction cells from LAF solutions for clinical applications. Copyright © 2014 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

  4. Occurrence and distribution of microplastics at selected coastal sites along the southeastern United States.

    PubMed

    Yu, Xubiao; Ladewig, Samantha; Bao, Shaowu; Toline, Catherine A; Whitmire, Stefanie; Chow, Alex T

    2018-02-01

    To investigate the occurrence and distribution of microplastics in the southeastern coastal region of the United States, we quantified the amount of microplastics in sand samples from multiple coastal sites and developed a predictive model to understand the drift of plastics via ocean currents. Sand samples from eighteen National Park Service (NPS) beaches in the Southeastern Region were collected and microplastics were isolated from each sample. Microplastic counts were compared among sites and local geography was used to make inferences about sources and modes of distribution. Samples were analyzed to identify the composition of particles using Fourier transform infrared spectroscopy (FTIR). To predict the spatiotemporal distribution and movements of particles via coastal currents, a Regional Ocean Modeling System (ROMS) was applied. Microplastics were detected in each of the sampled sites although abundance among sites was highly variable. Approximately half of the samples were dominated by thread-like and fibrous materials as opposed to beads and particles. Results of FTIR suggested that 24% consisted of polyethylene terephthalate (PET), while about 68% of the fibers tested were composed of man-made cellulosic materials such as rayon. Based on published studies examining sources of microplastics, the shape of the particles found here (mostly fibers) and the presence of PET, we infer the source of microplastics in coastal areas is mainly from urban areas, such as wastewater discharge, rather than breakdown of larger marine debris drifting in the ocean. Local geographic features, e.g., the nearness of sites to large rivers and urbanized areas, explain variance in amount of microplastics among sites. Additionally, the distribution of simulated particles is explained by ocean current patterns; computer simulations were correlated with field observations, reinforcing the idea that ocean currents can be a good predictor of the fate and distribution of microplastics at the sites sampled here. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Assessment tools for microplastics and natural fibres ingested by fish in an urbanised estuary.

    PubMed

    Halstead, Jennifer E; Smith, James A; Carter, Elizabeth A; Lay, Peter A; Johnston, Emma L

    2018-03-01

    Microplastics and fibres occur in high concentrations along urban coastlines, but the occurrence of microplastic ingestion by fishes in these areas requires further investigation. Herein, the ingestion of debris (i.e., synthetic and natural fibres and synthetic fragments of various polymer types) by three benthic-foraging fish species Acanthopagrus australis (yellowfin bream), Mugil cephalus (sea mullet) and Gerres subfasciatus (silverbiddy) in Sydney Harbour, Australia has been quantified and chemically speciated by vibrational spectroscopy to identify the polymer type. Ingested debris were quantified using gut content analysis, and identified using attenuated total reflectance Fourier transform infrared (ATR-FTIR) and Raman microspectroscopies in combination with principal component analysis (PCA). The occurrence of debris ingestion at the time of sampling ranged from 21 to 64% for the three species, and the debris number ranged from 0.2 to 4.6 items per fish for the different species, with ∼53% of debris being microplastic. There was a significant difference in the amount of debris ingested among species; however, there was no difference among species when debris counts were standardised to fish weight or gut content weight, indicating that these species ingest a similar concentration of debris relative to their ingestion rate of other material. ATR-FTIR microspectroscopy successfully identified 72% of debris. Raman spectroscopy contributed an additional 1% of successful identification. In addition, PCA was used to non-subjectively classify the ATR-FTIR spectra resulting in the identification of an additional 9% of the debris. The most common microplastics found were polyester (PET), acrylic-polyester blend, and rayon (semi-synthetic) fibres. The potential of using Raman microspectroscopy for debris identification was investigated and provided additional information about the nature of the debris as well as the presence of specific dyes (and hence potential toxicity). Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Low–Cost Bio-Based Carbon Fiber for High-Temperature Processing

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Naskar, Amit K.; Akato, Kokouvi M.; Tran, Chau D.

    GrafTech International Holdings Inc. (GTI), worked with Oak Ridge National Laboratory (ORNL) under CRADA No. NFE-15-05807 to develop lignin-based carbon fiber (LBCF) technology and to demonstrate LBCF performance in high-temperature products and applications. This work was unique and different from other reported LBCF work in that this study was application-focused and scalability-focused. Accordingly, the executed work was based on meeting criteria based on technology development, cost, and application suitability. The focus of this work was to demonstrate lab-scale LBCF from at least 4 different precursor feedstock sources that could meet the estimated production cost of $5.00/pound and have ash levelmore » of less than 500 ppm in the carbonized insulation-grade fiber. Accordingly, a preliminary cost model was developed based on publicly available information. The team demonstrated that 4 lignin samples met the cost criteria, as highlighted in Table 1. In addition, the ash level for the 4 carbonized lignin samples were below 500 ppm. Processing asreceived lignin to produce a high purity lignin fiber was a significant accomplishment in that most industrial lignin, prior to purification, had greater than 4X the ash level needed for this project, and prior to this work there was not a clear path of how to achieve the purity target. The lab scale development of LBCF was performed with a specific functional application in mind, specifically for high temperature rigid insulation. GTI is currently a consumer of foreignsourced pitch and rayon based carbon fibers for use in its high temperature insulation products, and the motivation was that LBCF had potential to decrease costs and increase product competitiveness in the marketplace through lowered raw material costs, lowered energy costs, and decreased environmental footprint. At the end of this project, the Technology Readiness Level (TRL) remained at 5 for LBCF in high temperature insulation.« less

  7. Atelier d'astronomie X

    NASA Astrophysics Data System (ADS)

    Ballet, J.; Barret, D.

    2001-01-01

    L'astronomie X connait aujourd'hui une de ses périodes les plus actives et les plus fastes, après le lancement de Chandra et XMM-Newton, et alors que Beppo SAX et Rossi XTE sont toujours en orbite. L'extraordinaire complémentarité de ces satellites est telle que leur domaine d'utilisation est extrêmement vaste, couvrant des étoiles jeunes aux toujours énigmatiques sursauts γ, en passant bien entendu par les trous noirs accrétants dans les binaires X ou dans les noyaux actifs de galaxies. L'atelier fut organisé selon quatre thèmes les étoiles, les phénomènes explosifs, les binaires X et les noyaux actifs de galaxies. Les résultats qui y furent présentés, pour chacun de ces thèmes témoignent de la superbe qualité des données obtenues. En particulier l'accès à la haute résolution spectrale (réseaux) en rayons X marque un pas important. Les présentations plus théoriques ont montré que parallèlement des progrès significatifs sont réalisés dans la physique de l'accrétion autour des objets compacts. Les actes de l'atelier donnent un panorama représentatif des progrès réalisés récemment par l'astronomie X, aussi bien du point de vue observationnel que théorique. Ces actes de colloque sont aussi l'occasion de rappeler l'historique et ce que furent les activités scientifiques de notre GdR au moment ou il doit s'intègrer au GdR PCHE et au PNPS. Enfin, pour toutes informations complémentaires concernant l'atelier: http://www.cesr.fr/~barret/adj/vg.html Ce site donne accès en particulier à la plupart des présentations (transparents).

  8. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Marra, J.

    The ore pitchblende was discovered in the 1750's near Joachimstal in what is now the Czech Republic. Used as a colorant in glazes, uranium was identified in 1789 as the active ingredient by chemist Martin Klaproth. In 1896, French physicist Henri Becquerel studied uranium minerals as part of his investigations into the phenomenon of fluorescence. He discovered a strange energy emanating from the material which he dubbed 'rayons uranique.' Unable to explain the origins of this energy, he set the problem aside. About two years later, a young Polish graduate student was looking for a project for her dissertation. Mariemore » Sklodowska Curie, working with her husband Pierre, picked up on Becquerel's work and, in the course of seeking out more information on uranium, discovered two new elements (polonium and radium) which exhibited the same phenomenon, but were even more powerful. The Curies recognized the energy, which they now called 'radioactivity,' as something very new, requiring a new interpretation, new science. This discovery led to what some view as the 'golden age of nuclear science' (1895-1945) when countries throughout Europe devoted large resources to understand the properties and potential of this material. By World War II, the potential to harness this energy for a destructive device had been recognized and by 1939, Otto Hahn and Fritz Strassman showed that fission not only released a lot of energy but that it also released additional neutrons which could cause fission in other uranium nuclei leading to a self-sustaining chain reaction and an enormous release of energy. This suggestion was soon confirmed experimentally by other scientists and the race to develop an atomic bomb was on. The rest of the development history which lead to the bombing of Hiroshima and Nagasaki in 1945 is well chronicled. After World War II, development of more powerful weapons systems by the United States and the Soviet Union continued to advance nuclear science. It was this defense application that formed the basis for the commercial nuclear power industry.« less

  9. Elaboration, microstructure, propriétés électriques et magnétiques de matériaux textures dans les systèmes Nd-Ce-Cu-O et Bi-Sr-Ca-Cu-O

    NASA Astrophysics Data System (ADS)

    Dhalenne, G.; Trouilleux, L.; Jegoudez, J.; Revcolevschi, A.; Monod, P.; Kormann, R.; Ganne, J. P.; Motohira, N.; Kitazawa, K.

    1991-11-01

    Superconducting textured materials were grown from the melt by a floating zone technique in the Nd-Ce-Cu-O and Bi-Sr-Ca-Cu-O systems. The influence of growth conditions and starting compositions on the microstructures and phase composition of the samples were studied by optical microscopy under polarized light, electron microprobe analysis and X-ray diffraction. The superconducting properties of these samples were examined by both electrical resistivity and magnetic measurements. A very strong influence of the microstructure on the superconducting properties as well as a magnetic and electrical anisotropy were shown. In the case of the Bi-Sr-Ca-Cu-O system, critical current densities ranging from 1 600 to 3 000 A.cm^{-2} were measured at 77 K. Des matériaux supraconducteurs texturés ont été élaborés à partir de l'état liquide dans les systèmes Nd-Ce-Cu-O et Bi-Sr-Ca-Cu-O par une technique de fusion de zone. L'influence des conditions de croissance et des compositions initiales sur la microstructure des échantillons a été étudiée par microscopie optique en lumière polarisée, microsonde électronique et diffraction des rayons X. Les propriétés supraconductrices des échantillons ont été examinées par des mesures électriques et magnétiques. Il a été observé une forte influence de la microstructure sur les propriétés supraconductrices ainsi qu'une anisotropie électrique et magnétique. Dans le cas du système Bi-Sr-Ca-Cu-O, les densités de courant critique mesurées à 77 K sont comprises entre 1 600 et 3 000 A.cm^{-2}.

  10. A registry for exposure and population health in the Altai region affected by fallout from the Semipalatinsk nuclear test site.

    PubMed

    Shoikhet, Y N; Kiselev, V I; Zaitsev, E V; Kolyado, I B; Konovalov, B Y; Bauer, S; Grosche, B; Burkart, W

    1999-09-01

    A registry of the rural population in the Altai region exposed to fallout from nuclear tests at the Semipalatinsk test site (STS) was established more than four decades after the first Soviet nuclear explosion on August 29, 1949. Information about individuals living in an exposed and a control area was collected using all available local sources, such as kolkhoz documentation, school registries, medical treatment records and interviews with residents. As a result, a database comprising an exposed group of 39 179 individuals from 53 Altai region villages, 6769 external and 3303 internal controls was compiled. For several settlements, effective dose estimates reached the level of 1.5 Sv, while the average effective dose estimate in the exposed group was 340 mSv. Dosimetric data, vital status information and health records gathered at rayon and village medical facilities are held in the registry. Cause-of-death information for deceased residents is obtained from death registration forms archived at the Altai region vital statistics office. At present, a follow-up of approximately 40% of the population exposed in 1949 has been done. More will be added by searching for migrants to the larger towns of the Altai region, i.e. Barnaul, Rubtsovsk and Biisk. In order to assess the influence of radiation exposure, analytical studies with a case-control design for stomach and lung cancer are currently being prepared. The number of known cases is sufficient to detect an odds ratio of 1.5 at the 95% confidence level. Epidemiological studies in populations affected by fallout from STS may be equally important to the atomic bomb survivors' study for the direct quantification of radiation effects. The range of exposure rates experienced will extend the acute high-dose-rate findings from Hiroshima/Nagasaki towards acute and protracted lower exposures, which are more relevant for radiation protection issues.

  11. Structure of a two-dimensional crystal in a Langmuir monolayer: grazing incidence X-ray diffraction and macroscopic properties

    NASA Astrophysics Data System (ADS)

    Flament, C.; Gallet, F.; Graner, F.; Goldmann, M.; Peterson, I.; Renault, A.

    1994-06-01

    Grazing incidence X-ray diffraction is performed on a Langmuir monolayer made of pure fluorescent NBD-stearic acid, spread at the free surface of water. It shows several intense narrow peaks in the solid phase, at the same wavevectors as the brightest peaks observed earlier by electron diffraction, for a monolayer transferred onto an amorphous polymer substrate. Thus the solid phase has the same crystalline structure on water and on solid substrate. The relative peak intensities are comparable in both experiments, and in the proposed model for the molecular structure. This model also accounts for the very large anisotropy of the crystalline phase and its optical properties. This phase could be ferroelectric, as previously assumed in order to explain the elongated shape of the crystals. Une monocouche de Langmuir, composée d'acide NBD-stéarique fluorescent pur, déposée à la surface libre de l'eau, est analysée par diffraction de rayons X sous incidence rasante. On détecte plusieurs pics étroits et intenses dans la phase solide, aux mêmes vecteurs d'onde que les pics les plus brillants précédemment observés par diffraction électronique, pour une monocouche transférée sur un substrat de polymère amorphe. La phase solide a donc la même structure cristalline sur l'eau et sur substrat solide. Les intensités relatives des pics sont comparables dans les deux expériences, ainsi que dans le modèle proposé pour la structure moléculaire. Ce modèle rend également compte de l'anisotropie très importante de la phase cristalline et de ses propriétés optiques. Il pourrait s'agir d'une phase ferroélectrique, comme cela avait été précédemment supposé pour expliquer la forme allongée des cristaux.

  12. Des ballons pour demain

    NASA Astrophysics Data System (ADS)

    Régipa, R.

    A partir d'une théorie sur la détermination des formes et des contraintes globales d'un ballon de révolution, ou s'en rapprochant, une nouvelle famille de ballons a été définie. Les ballons actuels, dits de ``forme naturelle'', sont calculés en général pour une tension circonférencielle nulle. Ainsi, pour une mission donnée, la tension longitudinale et la forme de l'enveloppe sont strictement imposées. Les ballons de la nouvelle génération sont globalement cylindriques et leurs pôles sont réunis par un câble axial, chargé de transmettre une partie des efforts depuis le crochet (pôle inférieur), directement au pôle supérieur. De plus, la zone latérale cylindrique est soumise à un faible champ de tensions circonférencielles. Ainsi, deux paramètres permettent de faire évoluer la distribution des tensions et la forme de l'enveloppe: - la tension du câble de liaison entre pôles (ou la longueur de ce câble) - la tension circonférencielle moyenne désirée (ou le rayon du ballon). On peut donc calculer et réaliser: - soit des ballons de forme adaptée, comme les ballons à fond plat pour le bon fonctionnement des montgolfières infrarouge (projet MIR); - soit des ballons optimisés pour une bonne répartition des contraintes et une meilleure utilisation des matériaux d'enveloppe, pour l'ensemble des programmes stratosphériques. Il s'ensuit une économie sensible des coûts de fabrication, une fiabilité accrue du fonctionnement de ces ballons et une rendement opérationnel bien supérieur, permettant entre autres, d'envisager des vols à très haute altitude en matériaux très légers.

  13. Advancements in vibroacoustic evaluation of satellite structures

    NASA Astrophysics Data System (ADS)

    Stavrinidis, C.; Witting, M.; Ikoss, S. I.; Klein, M.

    2001-02-01

    The importance of the launcher vibroacoustic environment is increasing with respect to satellite loads due to the increase in size and decrease in surface mass of lightweight appendages like antennas and solar arrays. The loads generated by the vibroacoustic environment need to be covered adequately to ensure satellite structural integrity. This is of particular importance in the low-frequency range where the low frequencies of light appendages and equipment couple with the acoustic environment. In order to cope with the increasing demand for prediction of structural loads due to the acoustic environment, various methods have been developed in the frame of ESA research and development activities. These range from simplified approaches with partial fluid-structure coupling, e.g. the POSTAR package provided by INTESPACE (France) to more sophisticated approaches with full fluid-structure coupling. In the frequency domain this includes pure finite element modelling techniques, where specific tools have been developed by FFA (Sweden) using the ASKA package, as well as coupled finite element—boundary element approaches that have been developed in cooperation with DASA-Dornier (Germany), STRACO (France) and FFA using the commercial packages ASKA and RAYON. For fully coupled fluid structure analysis in the time domain the ASTRYD code from METRAVIB (France) is employed where advancements have been supported by CNES. Applications of these tools range from simple benchmarks such as simply supported plates, cavity enclosures or generic satellite-fairing models to complex satellite structure configurations. Evaluations of antenna reflector structures (Artemis communication antenna) and satellite equipment panels (polar platform) are presented. The paper covers also the investigation of payload/fairing effects (influence of fairing helium purging on the coupled-system response) together with DASA-Dornier, FFA and STRACO, as well as the vibroacoustic analysis of solar array stacks carried out by FOKKER (The Netherlands) and METRAVIB, where the air effects in the inter panel gaps are being taken into account.

  14. Analytical methods in environmental effects-directed investigations of effluents.

    PubMed

    Hewitt, L Mark; Marvin, Chris H

    2005-05-01

    Effluent discharges are released into aquatic environments as complex mixtures for which there is commonly either no knowledge of the toxic components or a lack of understanding of how known toxicants interact with other effluent components. Effects-directed investigations consist of chemical extraction and iterative fractionation steps directed by a biological endpoint that is designed to permit the identification or characterization of the chemical classes or compounds in a complex mixture responsible for the observed biological activity. Our review of the literature on effects-directed analyses of effluents for non-mutagenic as well as mutagenic endpoints showed that common extraction and concentration methods have been used. Since the mid-1980s, the methods have evolved from the use of XAD resins to C18 solid-phase extraction (SPE). Blue cotton, blue rayon, and blue chitin have been used specifically for investigations of mutagenic activity where polycyclic compounds were involved or suspected. After isolation, subsequent fractionations have been accomplished using SPE or a high-pressure liquid chromatography (HPLC) system commonly fitted with a C18 reverse-phase column. Substances in active fractions are characterized by gas chromatography/mass spectrometry (GC-MS) and/or other spectrometric techniques for identification. LC-MS methods have been developed for difficult-to-analyze polar substances identified from effects-directed studies, but the potential for LC-MS to identify unknown polar compounds has yet to be fully realized. Salmonella-based assays (some miniaturized) have been coupled with fractionation methods for most studies aimed at identifying mutagenic fractions and chemical classes in mixtures. Effects-directed investigations of mutagens have focused mostly on drinking water and sewage, whereas extensive investigations of non-mutagenic effects have also included runoff, pesticides, and pulp mill effluents. The success of effects-directed investigations should be based on a realistic initial objective of each project. Identification of chemical classes associated with the measured biological endpoint is frequently achievable; however, confirmation of individual compounds is much more difficult and not always a necessary goal of effects-directed chemical analysis.

  15. Pitfalls in efficacy testing--how important is the validation of neutralization of chlorhexidine digluconate?

    PubMed

    Reichel, Mirja; Heisig, Peter; Kampf, Günter

    2008-12-02

    Effective neutralization of active agents is essential to obtain valid efficacy results, especially when non-volatile active agents like chlorhexidine digluconate (CHG) are tested. The aim of this study was to determine an effective and non-toxic neutralizing mixture for a propan-1-ol solution containing 2% CHG. Experiments were carried out according to ASTM E 1054-02. The neutralization capacity was tested separately with five challenge microorganisms in suspension, and with a rayon swab carrier. Either 0.5 mL of the antiseptic solution (suspension test) or a saturated swab with the antiseptic solution (carrier test) was added to tryptic soy broth containing neutralizing agents. After the samples were mixed, aliquots were spread immediately and after 3 h of storage at 2 - 8 degrees C onto tryptic soy agar containing a neutralizing mixture. The neutralizer was, however, not consistently effective in the suspension test. Immediate spread yielded a valid neutralization with Staphylococcus aureus, Staphylococcus epidermidis and Corynebacterium jeikeium but not with Micrococcus luteus (p < 0.001) and Candida albicans (p < 0.001). A 3-h storage period of the neutralized active agents in suspension resulted in significant carry-over activity of CHG in addition against Staphylococcus epidermidis (p < 0.001) and Corynebacterium jeikeium (p = 0.044). In the carrier test, the neutralizing mixture was found to be effective and non toxic to all challenge microorganisms when spread immediately. However, after 3 h storage of the neutralized active agents significant carry-over activity of CHG against Micrococcus luteus (p = 0.004; Tukey HSD) was observed. Without effective neutralization in the sampling fluid, non-volatile active ingredients will continue to reduce the number of surviving microorganisms after antiseptic treatment even if the sampling fluid is kept cold straight after testing. This can result in false-positive antiseptic efficacy data. Attention should be paid during the neutralization validation process to the amount of antiseptic solution, the storage time and to the choice of appropriate and sensitive microorganisms.

  16. Report of the annual statistical survey of the Japanese Society for Dialysis Therapy in 1996.

    PubMed

    Shinzato, T; Nakai, S; Akiba, T; Yamagami, S; Yamazaki, C; Kitaoka, T; Kubo, K; Maeda, K; Morii, H

    1999-02-01

    Nearly 170,000 patients were treated by maintenance renal replacement therapy (RRT) in Japan in 1996. The current status of Japanese patients on RRT might, in some way, be suggestive for patients on RRT in other countries. The Japanese Society for Dialysis Therapy conducts a questionnaire survey of virtually every dialysis facility in Japan at the end of each year. Here we present the results of our survey of patients undergoing RRT as of the end of 1996, as well as five-year trends (1992-1996) in some of the data. The response rate was 99.8%. At the end of 1996, there were 167,192 patients on maintenance RRT in Japan (1,328 persons per million population). The numbers of patients on maintenance RRT continued to increase during the five-year period. The gross mortality rate for that period ranged from 9.4% to 9.7%. Cuprammonium rayon was the most commonly used material (24.0%) for dialyzer membranes, followed by cellulose triacetate (18.7%). Approximately 5.0% of hemodialysis (HD) patients had a prior history of surgical release of carpal tunnel. The longer the years on HD therapy, the greater the proportion of patients with a history of such an operation. The predialysis plasma beta 2-microglobulin concentration was highest in patients aged 30 to 45 years and declined slightly after the age of 45. There was no significant difference in the HbA1c level between continuous ambulatory peritoneal dialysis and HD patients, both in whom diabetes was the disease causing renal failure. Moreover, among HD patients with diabetes, there was a clear tendency for the HbA1c level to be higher when the normalized protein catabolic rate was higher. This report summarizes the latest results of the survey on Japanese patients on RRT.

  17. Carbon Disulfide (CS2) Mechanisms in Formation of Atmospheric Carbon Dioxide (CO2) Formation from Unconventional Shale Gas Extraction and Processing Operations and Global Climate Change.

    PubMed

    Rich, Alisa L; Patel, Jay T

    2015-01-01

    Carbon disulfide (CS2) has been historically associated with the production of rayon, cellophane, and carbon tetrachloride. This study identifies multiple mechanisms by which CS2 contributes to the formation of CO2 in the atmosphere. CS2 and other associated sulfide compounds were found by this study to be present in emissions from unconventional shale gas extraction and processing (E&P) operations. The breakdown products of CS2; carbonyl sulfide (COS), carbon monoxide (CO), and sulfur dioxide (SO2) are indirect greenhouse gases (GHGs) that contribute to CO2 levels in the atmosphere. The heat-trapping nature of CO2 has been found to increase the surface temperature, resulting in regional and global climate change. The purpose of this study is to identify five mechanisms by which CS2 and the breakdown products of CS2 contribute to atmospheric concentrations of CO2. The five mechanisms of CO2 formation are as follows: Chemical Interaction of CS2 and hydrogen sulfide (H2S) present in natural gas at high temperatures, resulting in CO2 formation;Combustion of CS2 in the presence of oxygen producing SO2 and CO2;Photolysis of CS2 leading to the formation of COS, CO, and SO2, which are indirect contributors to CO2 formation;One-step hydrolysis of CS2, producing reactive intermediates and ultimately forming H2S and CO2;Two-step hydrolysis of CS2 forming the reactive COS intermediate that reacts with an additional water molecule, ultimately forming H2S and CO2. CS2 and COS additionally are implicated in the formation of SO2 in the stratosphere and/or troposphere. SO2 is an indirect contributor to CO2 formation and is implicated in global climate change.

  18. Seismic Risk Assessment for the Kyrgyz Republic

    NASA Astrophysics Data System (ADS)

    Pittore, Massimiliano; Sousa, Luis; Grant, Damian; Fleming, Kevin; Parolai, Stefano; Fourniadis, Yannis; Free, Matthew; Moldobekov, Bolot; Takeuchi, Ko

    2017-04-01

    The Kyrgyz Republic is one of the most socially and economically dynamic countries in Central Asia, and one of the most endangered by earthquake hazard in the region. In order to support the government of the Kyrgyz Republic in the development of a country-level Disaster Risk Reduction strategy, a comprehensive seismic risk study has been developed with the support of the World Bank. As part of this project, state-of-the-art hazard, exposure and vulnerability models have been developed and combined into the assessment of direct physical and economic risk on residential, educational and transportation infrastructure. The seismic hazard has been modelled with three different approaches, in order to provide a comprehensive overview of the possible consequences. A probabilistic seismic hazard assessment (PSHA) approach has been used to quantitatively evaluate the distribution of expected ground shaking intensity, as constrained by the compiled earthquake catalogue and associated seismic source model. A set of specific seismic scenarios based on events generated from known fault systems have been also considered, in order to provide insight on the expected consequences in case of strong events in proximity of densely inhabited areas. Furthermore, long-span catalogues of events have been generated stochastically and employed in the probabilistic analysis of expected losses over the territory of the Kyrgyz Republic. Damage and risk estimates have been computed by using an exposure model recently developed for the country, combined with the assignment of suitable fragility/vulnerability models. The risk estimation has been carried out with spatial aggregation at the district (rayon) level. The obtained results confirm the high level of seismic risk throughout the country, also pinpointing the location of several risk hotspots, particularly in the southern districts, in correspondence with the Ferghana valley. The outcome of this project will further support the local decision makers in implementing specific prevention and mitigation measures that are consistent with a broad risk reduction strategy.

  19. Analyse de l'interface cuivre/Teflon AF1600 par spectroscopie des photoelectrons rayons x

    NASA Astrophysics Data System (ADS)

    Popovici, Dan

    The speed of electrical signals through the microelectronic multilevel interconnects depends of the delay time R x C. In order to improve the transmission speed of future microdevices, the microelectronics industry requires the use of metals having lower resistivities and insulators having lower permittivities. Copper and fluoropolymers are interesting candidates for the replacement of the presently used Al/polyimide technology. This thesis presents an X-ray photoelectron spectroscopy (XPS) analysis of the Cu/Teflon AF1600 interface, in order to have a better understanding of those interfacial interactions leading to improved adhesion. Several deposition methods, such as evaporation, sputtering and laser-induced chemical deposition were analyzed and compared. X-ray photoelectron spectroscopy (XPS) was used as the primary characterization technique of the different surfaces and interfaces. In the case of evaporation and sputtering, the loss of fluorine and oxygen atoms leads to graphitization and the crosslinking of carbon chains. The extent of damage caused by copper deposition is higher for sputter deposition because of the higher energies of the incidents atoms. This energy (two orders of magnitude higher than the energy involved in the evaporation) is also responsible for the total reaction of Cu with F and C. For the physical depositions (sputtering and evaporation), an angle-resolved XPS diffusion study showed the copper distribution as a function of depth. (i) For sputter deposition, this distribution is uniform. (ii) In the case of evaporation, we computed the concentration profile using the inverse Laplace transform. Several samples, annealed at different temperatures, were used to calculate the diffusion coefficients for the Cu/Teflon AF1600 interface. The study of interactions at the interface between Teflon AF1600 and copper deposited by different metallization techniques permitted us to elucidate some aspects related to the chemistry and structure of the interface. The presence of the strong Cu-C bond may lead to an enhanced adhesion but a pretreatment (plasma RF, X-ray or excimer laser) is necessary to increase the surface concentration of reactive groups. (Abstract shortened by UMI.)

  20. Variations in snow cover seasonality across the Kyrgyz Republic from 2000 to 2016 revealed through MODIS Terra and Aqua snow products

    NASA Astrophysics Data System (ADS)

    Tomaszewska, M. A.; Henebry, G. M.

    2017-12-01

    The vertical transhumance practiced by herders in the highlands of Kyrgyzstan is vulnerable to environmental change. Herd movements and pasture conditions are both affected by spatial and temporal variations in snow cover and the timing of snowmelt. Early growing season soil moisture conditions affect the phenology and growth of vegetation, especially in the high elevation pastures used for summer forage. To evaluate snow seasonality, we examined three snow cover variables—the first day of snow (FDoS), the last day of snow (LDoS), and the duration of snow cover (DoSC) over 17 years based on 8-day snow product from MODIS Terra and Aqua (MOD/MYD10A2) across the Kyrgyz Republic (KYR). To track the "snow season" efficiently in the presence of snow-capped peaks, we start each snow season at day of year (DOY) 169, approximately the summer solstice, and extend to DOY 168 of the following year. To track the interannual variation of these variables, we applied two nonparametric statistics: the Mann-Kendall trend test and the Theil-Sen linear trend estimator. Our preliminary results focusing on four rayons in two oblasts indicate both large swaths of positive and negative significant trends over the different regions of the country. Positive trends in FDoS, meaning later snow arrival, were detected in parts of central KYR. Negative trends in FDoS meaning earlier arrival were detected at lower elevations in southwestern KYR. Earlier snowmelt (negative trend in LDoS) in eastern KYR resulted in a shorter snow season (negative trend in DoSC); in contrast, later snowmelt in southwestern KYR (positive trend in LDoS) resulted in a longer period of snow cover (positive trend of DoSC). We extend the analysis to the entire country and explore the influence of terrain attribites (elevation, slope, and aspect) and MODIS IGBP land cover type (MCD12Q1) on trends in snow cover seasonality. Additionally, we ran the trend tests for the Terra and Aqua snow products separately to evaluate the effect of overpass time on snow cover retrieval.

  1. Minimisation des inductances propres des condensateurs à film métallisé

    NASA Astrophysics Data System (ADS)

    Joubert, Ch.; Rojat, G.; Béroual, A.

    1995-07-01

    In this article, we examine the different factors responsible for the equivalent series inductance in metallized capacitors and we propose structures for capacitors that reduce this inductance. After recalling the structure of metallized capacitors we compare, by experimental measurements, the inductance due to the winding and that one added by the connections. The latter can become preponderant. In order to explain the experimental evolution of the winding impedance vs. frequency, we describe an analytical model which gives the current density in the winding and its impedance. This model enables us to determine the self resonant frequency for different types of capacitors. From where, we can infer the influence of the height of capacitors and their internal and external radius upon performances, It appears that to reduce the equivalent series inductance, it is better to use flat windings and annular windings. Dans cet article nous examinons les différents facteurs responsables de l'inductance équivalente série dans les condensateurs à film métallisé et proposons des géométries de condensateurs qui réduisent cette inductance. Après avoir rappelé la structure des condensateurs à film métallisé, nous comparons, par des mesures expérimentales, l'inductance due au bobinage et l'inductance ajoutée par les connexions. Cette dernière peut devenir prépondérante. Afin d'expliquer l'évolution de l'impédance du bobinage en fonction de la fréquence, nous décrivons un modèle analytique qui donne la densité du courant dans le bobinage et l'impédance de ce dernier. En outre, ce modèle permet de déterminer la fréquence de résonance série de divers types de condensateurs ce qui permet de déduire l'influence de la hauteur des condensateurs et de leurs rayons interne et externe sur les performances. Il apparaît ainsi que, pour diminuer l'inductance équivalente série, il vaut mieux employer des bobinages plats et des bobinages annulaires.

  2. [Mussolini's fight against occupational diseases (1922-1943): Italian leadership in the production of artificial silk].

    PubMed

    Carnevale, Francesco; Baldasseroni, Alberto

    2003-01-01

    After the end of the World War I Italy's economy was predominantly rural; industrialization had taken place only in the North-Western "Milan-Genoa-Turin triangle". Technological know-how and experience in developing the production cycles were scarce. The early experience in occupational medicine had been abruptly interrupted by the war. The attitudes of the Fascist regime with regard to work protection were ambiguous: work was claimed to be a sacred source of the national wealth worth being safeguarded by the regime, but the workers' potential to antagonize the regime was seen as a constant danger to public order. This scenery is well exemplified by a case study: Viscose-Ray-on Industry developed in synchrony with Mussolini's seizing power, in the early 20s. Thanks to the initiative of some manufacturers, Italy acquired a predominant role in this sector and became the second producer after the United States. Huge factories were created and complex equipment was imported from abroad. No attention was paid to health and safety at work. The major source of risk was carbon disulphide, used as a solvent in the production of xanthogenate starting from cellulose, the raw material; which produces progressive conditions following prolonged exposure. The slowness and the substantial inertia of the Fascist regime in the protection of workers' health contrasted with the reality in the Unit States, Italy's main competitor of Italy in the production of rayon. In order to exploit masses of workers, Fascism, unlike Nazism, needed no inferior "race": social discrimination was equally effective. Modern industrial development in Italy relied on masses of semiliterate farmers originating first from the Venetian region and later (after World War II) from Southern Italy. Shortly after 1945, during the so-called "Reconstruction-period", health protection developed slowly and circumspectly. National agencies supposed to have a proactive role in prevention, such as ENPI, confirmed their role as consultant of the employers for hygiene and prevention matters. Only the workers' fight around 1970 overcame the concept of the Corporative state introduced by the Fascism.

  3. Pitfalls in efficacy testing – how important is the validation of neutralization of chlorhexidine digluconate?

    PubMed Central

    Reichel, Mirja; Heisig, Peter; Kampf, Günter

    2008-01-01

    Background Effective neutralization of active agents is essential to obtain valid efficacy results, especially when non-volatile active agents like chlorhexidine digluconate (CHG) are tested. The aim of this study was to determine an effective and non-toxic neutralizing mixture for a propan-1-ol solution containing 2% CHG. Methods Experiments were carried out according to ASTM E 1054-02. The neutralization capacity was tested separately with five challenge microorganisms in suspension, and with a rayon swab carrier. Either 0.5 mL of the antiseptic solution (suspension test) or a saturated swab with the antiseptic solution (carrier test) was added to tryptic soy broth containing neutralizing agents. After the samples were mixed, aliquots were spread immediately and after 3 h of storage at 2 – 8°C onto tryptic soy agar containing a neutralizing mixture. Results The neutralizer was, however, not consistently effective in the suspension test. Immediate spread yielded a valid neutralization with Staphylococcus aureus, Staphylococcus epidermidis and Corynebacterium jeikeium but not with Micrococcus luteus (p < 0.001) and Candida albicans (p < 0.001). A 3-h storage period of the neutralized active agents in suspension resulted in significant carry-over activity of CHG in addition against Staphylococcus epidermidis (p < 0.001) and Corynebacterium jeikeium (p = 0.044). In the carrier test, the neutralizing mixture was found to be effective and non toxic to all challenge microorganisms when spread immediately. However, after 3 h storage of the neutralized active agents significant carry-over activity of CHG against Micrococcus luteus (p = 0.004; Tukey HSD) was observed. Conclusion Without effective neutralization in the sampling fluid, non-volatile active ingredients will continue to reduce the number of surviving microorganisms after antiseptic treatment even if the sampling fluid is kept cold straight after testing. This can result in false-positive antiseptic efficacy data. Attention should be paid during the neutralization validation process to the amount of antiseptic solution, the storage time and to the choice of appropriate and sensitive microorganisms. PMID:19046465

  4. An investigation of the effects of relevant samples and a comparison of verification versus discovery based lab design

    NASA Astrophysics Data System (ADS)

    Rieben, James C., Jr.

    This study focuses on the effects of relevance and lab design on student learning within the chemistry laboratory environment. A general chemistry conductivity of solutions experiment and an upper level organic chemistry cellulose regeneration experiment were employed. In the conductivity experiment, the two main variables studied were the effect of relevant (or "real world") samples on student learning and a verification-based lab design versus a discovery-based lab design. With the cellulose regeneration experiment, the effect of a discovery-based lab design vs. a verification-based lab design was the sole focus. Evaluation surveys consisting of six questions were used at three different times to assess student knowledge of experimental concepts. In the general chemistry laboratory portion of this study, four experimental variants were employed to investigate the effect of relevance and lab design on student learning. These variants consisted of a traditional (or verification) lab design, a traditional lab design using "real world" samples, a new lab design employing real world samples/situations using unknown samples, and the new lab design using real world samples/situations that were known to the student. Data used in this analysis were collected during the Fall 08, Winter 09, and Fall 09 terms. For the second part of this study a cellulose regeneration experiment was employed to investigate the effects of lab design. A demonstration creating regenerated cellulose "rayon" was modified and converted to an efficient and low-waste experiment. In the first variant students tested their products and verified a list of physical properties. In the second variant, students filled in a blank physical property chart with their own experimental results for the physical properties. Results from the conductivity experiment show significant student learning of the effects of concentration on conductivity and how to use conductivity to differentiate solution types with the use of real world samples. In the organic chemistry experiment, results suggest that the discovery-based design improved student retention of the chain length differentiation by physical properties relative to the verification-based design.

  5. Texturation à froid sous contraintes triaxiales de phase à haute T_c de Bi(Pb)SrCaCuO préréagie

    NASA Astrophysics Data System (ADS)

    Langlois, P.; Massat, H.; Suryanarayanan, R.

    1994-11-01

    The alignment of grains in isostatically precompacted samples of prereacted Bi{1,8}Pb{0,4}Sr{2,0}Ca{2,2}Cu{3,0}O{10,3 + x} powder has been achieved by compressive plastic deformation under isostatic pressure at room temperature. Isostatic pressures were in the range 0.1 to 1 GPa and deformation rates were led up to 57 %. Prior to sintering, X-ray diffraction measurements corroborate an expected high- T_c phase purity of nearly 85 % and indicate that the as-deformed samples have been textured with the (c-axes parallel to the pressing direction whilst a.c. susceptibility measurements ascertain a high transition temperature around 107 K. Intergranular connection does not occur until sintering at 850 ^{circ}C for 80 h and measurements indicate then that the texture has been retained. Superconducting properties themselves show sensitivity to texture through anisotropy-related distinctive irreversibility lines. L'alignement de grains de poudre Bi{1,8}Pb{0,4}Sr{2,0}Ca{2,2}Cu{3,0}O{10,3 + x} préréagie a été réalisé par déformation plastique à température ambiante d'échantillons précompactés isostatiquement et comprimés sous pression isostatique, la gamme des pressions isostatiques allant de 0,1 à 1 GPa et les taux de déformation atteignant 57 %. Les mesures de diffraction de rayons X corroborent la pureté de phase à haute T_c proche de 85 % attendue et indiquent que les échantillons ainsi déformés ont été texturés avec les plans ab perpendiculaires à la direction de compression. Les mesures de susceptibilité alternative avèrent une température élevée de transition à environ 107 K mais la connexion intergranulaire n'est assurée qu'après un frittage à 850 ^{circ}C pendant 80 h dont on vérifie qu'il conserve la texture. Enfin, la sensibilité des propriétés supraconductrices à la texturation est évaluée par le biais de lignes d'irréversibilité distinctes en fonction de l'anisotropie.

  6. Applications of scientific imaging in environmental toxicology

    NASA Astrophysics Data System (ADS)

    El-Demerdash, Aref M.

    The national goals of clean air, clean water, and healthy ecosystems are a few of the primary forces that drive the need for better environmental monitoring. As we approach the end of the 1990s, the environmental questions at regional to global scales are being redefined and refined in the light of developments in environmental understanding and technological capability. Research in the use of scientific imaging data for the study of the environment is urgently needed in order to explore the possibilities of utilizing emerging new technologies. The objective of this research proposal is to demonstrate the usability of a wealth of new technology made available in the last decade to providing a better understanding of environmental problems. Research is focused in two imaging techniques macro and micro imaging. Several examples of applications of scientific imaging in research in the field of environmental toxicology were presented. This was achieved on two scales, micro and macro imaging. On the micro level four specific examples were covered. First, the effect of utilizing scanning electron microscopy as an imaging tool in enhancing taxa identification when studying diatoms was presented. Second, scanning electron microscopy combined with energy dispersive x-ray analyzer were demonstrated as a valuable and effective tool for identifying and analyzing household dust samples. Third, electronic autoradiography combined with FT-IR microscopy were used to study the distribution pattern of [14C]-Malathion in rats as a result of dermal exposure. The results of the autoradiography made on skin sections of the application site revealed the presence of [ 14C]-activity in the first region of the skin. These results were evidenced by FT-IR microscopy. The obtained results suggest that the penetration of Malathion into the skin and other tissues is vehicle and dose dependent. The results also suggest the use of FT-IR microscopy imaging for monitoring the disposition of insecticides in biological tissues. Finally, in the microscale level, the penetration of household insecticides through different types of textiles fabrics. The results obtained from the fluorescence spectra, SFC and SEM showed that cotton-polyester (twill), cotton, wool and cotton thermal underwear were the least penetrable materials for the aerosols. On the other hand, acrylic and artificial silk (rayon) were the most penetrable cloth types. The most protective form of clothing will be more than one layer e.g. cotton/polyester type of clothing. (Abstract shortened by UMI.)

  7. Structure des fluides de bâtonnets polaires et polarisables dans l'approximation des chaînes hypertressées avec amplification du potentiel répulsif. Un modèle simple d'acétonitrile liquide.

    NASA Astrophysics Data System (ADS)

    Salamito, B.; Fries, P. H.

    1991-07-01

    We study fluids of rigid rods which are generated by a distribution of line sites and which carry a polarizable electric point dipole at their centre. We examine the difficulties for solving the integral equations, which result from truncating the rotational invariant expansion of the usual intermolecular rapidly varying shape potentials. In order to overcome these convergence problems, soft shape potentials are used in addition to an approximation HNCAR, of the hypernetted chain (HNC) type, which Amplifies these soft Repulsive effects. The polarization due to all the molecules is treated at a self-consistent mean field level. This formalism is applied to a model of liquid acetonitrile at 291K. The Kirkwood factors, the dielectric constant, and the cross sections of neutron or X-rays diffraction studies are in good agreement with experiment. This justifies the theoretical molecular pair distribution, from which the local molecular order is carefully analyzed. On étudie des fluides de bâtonnets rigides engendrés par une distribution de sites alignés et portant en leur centre un dipôle électrique ponctuel polarisable. On examine les difficultés de résolution des équations intégrales liées à la troncature du développement en invariants rotationnels des potentiels de forme intermoléculaires usuels à variation rapide. Pour contourner ces problèmes de convergence on utilise des potentiels de forme molle combinés à une approximation HNCAR, du type des chaînes hypertressées (HNC), qui Amplifie ces effets Répulsifs mous. On traite la polarisation due à l'ensemble des molécules par une approximation auto-cohérente de champ moyen. On applique ce formalisme à un modèle d'acétonitrile liquide à 291K. Les facteurs de Kirkwood, la constante diélectrique et les sections efficaces de diffusion des neutrons ou des rayons X calculés sont en bon accord avec l'expérience. Ceci justifie la distribution théorique de paires de molécules à partir de laquelle on analyse en détail l'ordre moléculaire local.

  8. Especially for High School Teachers

    NASA Astrophysics Data System (ADS)

    Emory Howell, J.

    1999-11-01

    More Feature Articles This Month This issue contains a larger-than-usual number of Secondary School Chemistry feature articles (see side-bar). Mary Harris, who teaches in St. Louis, Missouri, and her student, Lauren Picard, contributed an account of student research on the cuprammonium rayon process (p 1512). In addition to being informative and interesting, the article provides a model for student-teacher interaction in carrying out an independent research project. Two North Carolina teachers, Charles Roser and Catherine McCluskey, describe how to use a Calculator Based Laboratory (interface) to measure the kinetics of the reaction that occurs when a lightstick is activated (p 1514). The method and the easy-to-construct device they made could be used with other systems, as well. Don't Throw Away the Carrier Sheet All areas of JCE Online are now accessible to all JCE subscribers. To find out how you can benefit, read the article appearing on p 1599, Now That I Have It, What Can I Do with It? Jon Holmes, Editor of JCE Online, explains in the article how you can use this resource most effectively. Access to several areas, such as full text access to articles, requires that you log in. The mailing label on the carrier sheet that accompanies your Journal each month contains a password that you need to log in. That is why you need to keep the carrier sheet, at least until you have logged in for the first time and either memorized the number or written it in a safe place. Detailed instructions for logging on are found by clicking on the "How to Log On" link, which appears near the upper left corner of the JCE Online Home Page, jchemed.chem.wisc.edu. If you read a school library copy you need to ask your librarian what password you need to log in. Congratulations Among the recipients of the most prestigious American Society Awards (p 1481) are two individuals who have given generously of their time and energy to the cause of chemical education. Both are familiar names to many of our readers. The High School/College Interface Luncheon was part of the very rich day-long High School Program at the New Orleans ACS Meeting. Shown here (from left) are Glenn Crosby, the luncheon speaker; Lillie Tucker-Akin, the High School Day program chair; and Fred Johnson, Assistant Superintendent of Shelby County (TN) schools and Immediate Past President of NSTA. The recipient of the James Bryant Conant Award in High School Chemistry Teaching is Frank G. Cardulla, who taught for many years at Niles North High School, Skokie, Illinois. His extensive record of service to fellow teachers includes editing the JCE "View from My Classroom" feature for several years and writing several articles, as well as his recent appointment to the JCE Board of Publication. The recipient of the George C. Pimentel Award in Chemical Education is Jerry A. Bell of the American Chemical Society in Washington, DC. An author of numerous articles appearing in JCE and a member of the JCE Board of Publication for several years, he currently serves as Board Chair. The 16th Biennial Conference on Chemical Education Readers who attended the 15th BCCE in Waterloo, Ontario, know that much of the programming at these conferences is of interest to high school teachers. Many work shops, papers, and demonstrations are presented by high school teachers. There are many other outstanding papers and posters, plenary speakers, and exciting demonstrations. The 16th BCCE will be held at the University of Michigan in Ann Arbor, July 30-August 3, 2000. Among the high school teachers already scheduled to present workshops at the 16th BCCE are George Hague, Lynn Hershey, and Jack Randall, and there will be many more before the program is completed. The High School Chemistry Program Chair is Tim Graham, Roosevelt High School (MI). The Organizing Committee is seeking the assistance of local sections of the American Chemical Society within a 300-mile radius of Ann Arbor in providing support for high school teachers to attend the conference. High school teachers who wish to attend, whether within the 300-mile radius or beyond, are encouraged to contact their local section of the ACS. Information about local sections can be found on the Web at www.acs.org. See p 1482 for more information about the conference, including deadlines for proposals and abstracts and for the conference Web site address. Secondary School Feature Articles * The Chemistry of Modern Dental Filling Materials, by John W. Nicholson and H. Mary Anstice, p 1497 * JCE Classroom Activity #21: Hunting for Chemicals in Consumer Products, p 1504A, by Arthur M. Last * Science for Kids Outreach Programs, by Birgit G. Koehler, Lee Y. Park, and Lawrence J. Kaplan, p 1505 *Henry's Law and Noisy Knuckles by Doris R. Kimbrough, p 1509 *Investigating the Cuprammonium Rayon Process in a High School Laboratory, by Lauren J. Pickard and Mary E. Harris, p 1512 * Lightstick Kinetics, by Charles E. Roser and Catherine L. McCluskey, p 1514

  9. Remarks on Polyelectrolyte Conformation

    NASA Astrophysics Data System (ADS)

    de Gennes, P. G.; Pincus, P.; Velasco, R. M.; Brochard, F.

    Nous discutons des conformations de polymères linéaires chargés en faisant les hypothèses suivantes : a) la chaĬne sans charge est flexible, b) la force éctrostatique domine les interactions monomère-monomère c) il n'y a pas de sels. 1) Pour le cas dilué (chaĬne non enchevetrees) en corrigeant le calcul self-consistant fait récemment par Richmond [1a], on trouve une taille des polyions égale a = R ND, qui est une fonction linéaire de l'indice de polymérisation N. Ce rèsultat est en accord avec les prècèdents travaux de Hermans et Overbeek [1b], Kuhn, Kunzle et Katchalsky [1c]. 2) Il existe un domaine pour des concentrations très petites c (c** < c < c*) oò les interactions èlectrostatiques entre les polyions sont supèrieures aux ènergies thermiques, il semble donc possible que les polyions puissent former un rèseau pèriodique à trois dimensions. Nèanmoins, il semble difficile de mettre en èvidence un rèseau si diluè. 3) Jusqu'ici toutes les expériences avec les polyélectrolytes sans sels ont été pratiquement faites à des concentrations c > c*, pour lesquelles les différentes cha.nes sont enchevêtrées. Pour discuter ce régime on s.intéresse uniquement au cas où la charge par unité de longueur est près du (ou audessus du) seuil de condensation, donc il existe une seule longueur ξ(c) caractérisant les corrélations; à trois dimensions 03BE a le même comportement que le rayon de Debye pour les contre-ions. On a considéré quelques conformations possibles : a) un réseau hexagonal de batonnets; b) un réseau cubique de batonnets; c) une phase isotrope de cha.nes partiellement flexibles. Les différentes structures formées de batonnets semblent avoir la même énergie électrostatique. Ce fait suggère que la phase isotrope peut être la plus favorable. On analyse cette dernière phase en utilisant les mêmes méthodes qui se sont révélées efficaces pour les solutions des polymères neutres. Dans le modèle isotrope chaque cha.ne a le comportement d.une succession des petites pelotes (blobs) de taille 03BE. Les effets électrostatiques sont importants à l.intérieur d'un blobs et analogues au cas (1). Mais ces interactions sont écrantées entre les blobs ; chaque cha.ne a un comportement idéal à grande échelle et son rayon est R(c) ~ c-¼ N½. Si on suppose que les effets dynamiques des enchevêtrements sont faibles on trouve une valeur pour la viscosité ηsp/c ~ Nc-½ We discuss the conformations of linear polyions assuming that a) the corresponding uncharged chain is flexible ; b) electrostatic forces dominate the monomer-monomer interactions; c) no salt is added. 1) For the dilute case (non overlapping chains) correcting a recent self-consistent calculation by Richmond [1a], we find an overall polyion size R = Nd which is a linear function of the polymerization index N in agreement with the early work of Hermans and Overbeek, [1b], Kuhn, Kunzle, and Katchalsky [1c]. 2) There is a range of very low concentration c (c** < c < c*) where the chains do not overlap (c < c*) but where the electrostatic interactions between polyions are much larger than thermal energies (c > c**) : here we expect that the polyions build up a 3-dimensional periodic lattice ; however, the detection of such an extremely dilute lattice appears difficult. 3) Practically all experiments on salt-free polyelectrolytes have been performed at concentrations c > c* where different chains overlap each other. To discuss this regime we restrict our attention to cases where the charge per unit length is near (or above) the condensation threshold : then a single length ξ(c) characterizes the correlation; in 3 dimensions ξ scales like the Debye radius associated with the counter ions. We consider several possible conformations : a) hexagonal lattice of rigid rods ; b) cubic lattice of rigid rods; c) isotropic phase of partially flexible chains. The various rigid rod structures appear to have very similar electrostatic energies. This suggests that the isotropic phase might possibly be the most favorable. We analyse this latter phase using the same scaling methods which have recently been helpful for neutral polymer solutions (2). In the isotropic model each chain behaves like a succession of segments of size. Inside one segment electrostatic effects are important and similar to case (1) above. Between segments the interactions are screened out, and tach chain is ideal on a large scale, with radius R(c) ~ c-¼ N½. If we (tentatively) assume that the dynamical effects of entanglements are weak, we are than led to a viscosity ηsp/c ~ Nc-½.

  10. Single atomic particle at rest in free space : new value for electron radius

    NASA Astrophysics Data System (ADS)

    Dehmelt, H.

    Zero-point confinement in a suitable trap is briefly discussed as a quantum-mechanical equivalent of the classical single particle at rest in free space. So far, such confinement has been realized only for the 150 GHz cyclotron motion in geonium, a single electron permanently confined in a Penning trap. The most important result of mono-ion spectroscopy is a new, 10 000 times smaller, radius for the electron. This result was obtained by analyzing our g-factor data, g/2 = 1.001 159 652 193 (4), on the basis of a near-Dirac particle model. RF spectroscopy in geonium relies on the Continuous Stem Gerlach Effect in which a spin flip is detected as a small change in the ~ 60 MHz axial oscillation frequency of the electron in the trap. The Kaufmann Effect or relativistic mass shift may become a superior alternative : operating a geonium apparatus as a frequency selective mini-synchro-cyclotron has produced an easily detectable shift in the axial frequency. Like in Habann's 1926 split-anode magnetron, energy is quickly transferred from the oscillating electron to a resonant circuit, but by us for the purpose of detection, damping and cooling of the oscillatory motion. Conversely, localizing the electron to ~ 60 μm in the node of a standing wave in the trap cavity, where this cavity looks like a short, when it is resonant with the cyclotron motion, has made it possible to decrease the natural line width ten-fold. By driving the axial frequency not on resonance but on a side band higher by the ~ 12 kHz magnetron frequency, it has been possible to force the magnetron motion to absorb the excess in the photon energy and thereby shrink the magnetron radius to ~ 15 μm. By an analogous laser spectroscopic procedure the oscillation amplitude of a Ba+ ion in a different trap has been reduced to ~ 120 nm or less. Like in Nuclear Magnetic Resonance, confinement is now much smaller than the wave length and no motional side bands appear in the optical spectrum. Such a mono-ion oscillator, but using Tl+ or a similar ion, may make an optical frequency standard with a 1 000-day reproducibility of 10 -18 possible and thereby allow one to watch the expansion of the universe from one's laboratory. Nous décrivons brièvement l'équivalent quantique d'une particule classique unique au repos dans l'espace libre : le confinement de point zéro dans un piège. Jusqu'à maintenant, ce confinement n'a été réalisé que pour le mouvement cyclotron (150 GHz) du géonium. un électron unique confiné dans un piège de Penning. Le résultat le plus important de la spectroscopie de particules piégées est un nouveau rayon de l'électron, 10 000 fois plus petit. Ce résultat a été obtenu à partir des données concernant le facteur g, g/2 = 1,001 159 652 193 (4), et sur la base d'un modèle de particule voisin du modèle de Dirac. La spectroscopie RF du géonium repose à l'heure actuelle sur l'effet Stern et Gerlach continu, dans lequel un basculement de spin est détecté grâce au faible changement qu'il induit sur la fréquence d'oscillation axiale de l'électron dans le piège (60 MHz). La variation relativiste de la masse, ou effet Kaufmann, pourrait s'avérer être à la base d'une méthode plus sensible : l'utilisation du géonium comme un mini-synchro-cyclotron sélectif en fréquence permet en effet de produire un déplacement aisément détectable de la fréquence axiale. Comme dans le magnétron « split-anode » de Habann (1926), l'énergie est rapidement transférée de l'électron oscillant vers un circuit résonnant, ce transfert servant dans notre expérience à la détection, au freinage et au refroidissement du mouvement oscillant. Nous avons ainsi pu localiser l'électron sur 60 μm, au nœud d'une onde stationnaire formée dans la cavité du piège, cette cavité étant résonnante et se comportant alors comme un court-circuit; ceci a permis une diminution de la largeur naturelle de la raie détectée par un facteur 10. En excitant le mouvement axial par une raie décalée de la résonance « vers le bleu », d'une quantité égale à la fréquence magnétron (12 kHz), nous avons pu transférer au mouvement magnétron l'énergie correspondant au décalage de fréquence et ainsi réduire le rayon magnétron à 15 μm. Par une procédure analogue, en spectroscopie laser, l'amplitude d'oscillation d'un ion Ba+ piégé a été réduite à moins de 120 nm. Comme en RMN, la région de confinement est maintenant beaucoup plus petite que la longueur d'onde, et aucune raie latérale due au mouvement n'apparaît dans le spectre optique. Un tel oscillateur, fonctionnant avec un ion Tl+ ou un ion similaire, pourrait constituer un standard de fréquence optique avec une reproductibilité de 10-18 sur 1 000 jours et pourrait ainsi permettre l'observation de l'expansion de l'univers en laboratoire.

  11. Low-Cost Bio-Based Carbon Fibers for High Temperature Processing

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Paul, Ryan Michael; Naskar, Amit

    GrafTech International Holdings Inc. (GTI), under Award No. DE-EE0005779, worked with Oak Ridge National Laboratory (ORNL) under CRADA No. NFE-15-05807 to develop lignin-based carbon fiber (LBCF) technology and to demonstrate LBCF performance in high-temperature products and applications. This work was unique and different from other reported LBCF work in that this study was application-focused and scalability-focused. Accordingly, the executed work was based on meeting criteria based on technology development, cost, and application suitability. High-temperature carbon fiber based insulation is used in energy intensive industries, such as metal heat treating and ceramic and semiconductor material production. Insulation plays a critical rolemore » in achieving high thermal and process efficiency, which is directly related to energy usage, cost, and product competitiveness. Current high temperature insulation is made with petroleum based carbon fibers, and one goal of this protect was to develop and demonstrate an alternative lignin (biomass) based carbon fiber that would achieve lower cost, CO2 emissions, and energy consumption and result in insulation that met or exceeded the thermal efficiency of current commercial insulation. In addition, other products were targeted to be evaluated with LBCF. As the project was designed to proceed in stages, the initial focus of this work was to demonstrate lab-scale LBCF from at least 4 different lignin precursor feedstock sources that could meet the estimated production cost of $5.00/pound and have ash level of less than 500 ppm in the carbonized insulation-grade fiber. Accordingly, a preliminary cost model was developed based on publicly available information. The team demonstrated that 4 lignin samples met the cost criteria. In addition, the ash level for the 4 carbonized lignin samples was below 500 ppm. Processing as-received lignin to produce a high purity lignin fiber was a significant accomplishment in that most industrial lignin, prior to purification, had greater than 4X the ash level needed for this project, and prior to this work there was not a clear path of how to achieve the purity target. The lab scale development of LBCF was performed with a specific functional application in mind, specifically for high temperature rigid insulation. GTI is a consumer of foreign-sourced pitch and rayon based carbon fibers for use in its high temperature insulation products, and the motivation was that LBCF had potential to decrease costs and increase product competitiveness in the marketplace through lowered raw material costs, lowered energy costs, and decreased environmental footprint. At the end of this project, the Technology Readiness Level (TRL) remained at 5 for LBCF in high temperature insulation.« less

  12. Modelisation de la Propagation des Ondes Sonores dans un Environnement Naturel Complexe

    NASA Astrophysics Data System (ADS)

    L'Esperance, Andre

    Ce travail est consacre a la propagation sonore a l'exterieur dans un environnement naturel complexe, i.e. en presence de conditions reelles de vent, de gradient de temperature et de turbulence atmospherique. Plus specifiquement ce travail comporte deux objectifs. D'une part, il vise a developper un modele heuristique de propagation sonore (MHP) permettant de prendre en consideration l'ensemble des phenomenes meteorologiques et acoustiques influencant la propagation du son a l'exterieur. D'autre part, il vise a identifier dans quelles circonstances et avec quelle importance les conditions meteorologiques interviennent sur la propagation sonore. Ce travail est divise en cinq parties. Apres une breve introduction identifiant les motivations de cette etude (chapitre 1), le chapitre 2 fait un rappel des travaux deja realises dans le domaine de la propagation du son a l'exterieur. Ce chapitre presente egalement les bases de l'acoustique geometrique a partir desquelles ont ete developpees la partie acoustique du modele heuristique de propagation. En outre, on y decrit comment les phenomenes de refraction et de turbulence atmospherique peuvent etre consideres dans la theorie des rayons. Le chapitre 3 presente le modele heuristique de propagation (MHP) developpe au cours de cet ouvrage. La premiere section de ce chapitre decrit le modele acoustique de propagation, modele qui fait l'hypothese d'un gradient de celerite lineaire et qui est base sur une solution hybride d'acoustique geometrique et de theorie des residus. La deuxieme section du chapitre 3 traite plus specifiquement de la modelisation des aspects meteorologiques et de la determination des profils de celerite et des index de fluctuation associes aux conditions meteorologiques. La section 3 de ce chapitre decrit comment les profils de celerite resultants sont linearises pour les calculs dans le modele acoustique, et finalement la section 4 donne les tendances generales obtenues par le modele. Le chapitre 4 decrit les compagnes de mesures qui ont ete realisees a Rock-Spring (Pennsylvanie, Etats -Unis) au cours de l'ete 90 et a Bouin (Vendee, France) au cours de l'automne 91. La campagne de mesure de Rock -Spring a porte plus specifiquement sur les effets de la refraction alors que la campagne de Bouin a prote plus specifiquement sur les effets de la turbulence. La section 4.1 decrit les equipements et le traitement des donnees meteorologiques realisees dans chaque cas et la section 4.2 fait de meme pour les resultats acoustiques. Finalement, le chapitre 5 compare les resultats experimentaux obtenus avec ceux donnes par le MHP, tant pour les resultats meteorologiques que pour les resultats acoustiques. Des comparaisons avec un autre modele (le Fast Field Program) sont egalement presentees.

  13. Études par diffraction haute résolution et réflectivité de films minces épitaxiés

    NASA Astrophysics Data System (ADS)

    Baulès, P.; Casanove, M. J.; Roucau, C.; Ousset, J. C.; Bobo, J. F.; Snoeck, E.; Magnoux, D.; Gatel, C.

    2002-07-01

    The studies we present concern the general researches involved in order to understand the growth mechanisms of thin films deposited on oriented substrates. Among the different investigation technics of the thin layers, X-ray diffraction and reflectivity will be discussed through two applications. In a first step, thediffraction presented, illustrated by reciprocal space mapping, will give information about the layer state of stress and the lattice distorsion of La{1-x}SrxMnO3 deposited on SrTiO3. The results obtained are discussed and compared to those given by electron microscopy. In a second step, we will present an application of reflectivity concerning a very roughness surface of platinum deposited on MgO showing an island growth process. We will verify that reflectivity can lead to the determination of the recovered rate of the surface, even if some problems exist in the simulation of the whole data set. Results obtained in electron microscopy will complete those issued from reflectivity. Les études que nous allons présenter sont à replacer dans le contexte général de la compréhension des mécanismes de croissance des films minces déposés sur des substrats orientés. Parmi les diverses techniques d'investigations des couches minces, la diffraction et la réflectivité des rayons X vont être abordées à travers deux applications. Nous verrons tout d'abord que la diffraction, illustrée par la cartographie en deux dimension du réseau réciproque, permet de remonter à l'état de contrainte ainsi qu'à la déformation de la maille de La{1-x}SrxMnO3 déposé sur SrTiO3. Les résultats déduits de ces mesures seront discutés et comparés à ceux obtenus en microscopie électronique. Dans la suite de l'article, nous verrons une des applications de la réflectivité, sur une surface très perturbée de platine déposé sur MgO et présentant une croissance en îlots. Nous verrons que la réflectivité permet d'estimer le taux de recouvrement de la surface, mais que des problèmes persistent dans la simulation de l'intégralité des données expérimentales. Les résultats obtenus en MET viendront compléter ceux issus de la réflectivité.

  14. Formation des etoiles massives dans les galaxies spirales

    NASA Astrophysics Data System (ADS)

    Lelievre, Mario

    Le but de cette thèse est de décrire la formation des étoiles massives dans les galaxies spirales appartenant à divers types morphologiques. L'imagerie Hα profonde combinée à une robuste méthode d'identification des régions HII ont permis de détecter et de mesurer les propriétés (position, taille, luminosité, taux de formation d'étoiles) de plusieurs régions HII situées dans le disque interne (R < R25) de dix galaxies mais aussi à leur périphérie (R ≥ R 25). De façon générale, la répartition des régions HII ne montre aucune évidence de structure morphologique à R < R25 (bras spiraux, anneau, barre) à moins de limiter l'analyse aux régions HII les plus grosses ou les plus lumineuses. La répartition des régions HII, de même que leur taille et leur luminosité, sont toutefois sujettes à de forts effets de sélection qui dépendent de la distance des galaxies et qu'il faut corriger en ramenant l'échantillon à une résolution spatiale commune. Les fonctions de luminosité montrent que les régions HII les plus brillantes ont tendance à se former dans la portion interne du disque. De plus, l'analyse des pentes révèle une forte corrélation linéaire par rapport au type morphologique. Aucun pic n'est observé dans les fonctions de luminosité à log L-37 qui révèlerait la transition entre les régions HII bornées par l'ionisation et par la densité. Une relation cubique est obtenue entre la taille et la luminosité des régions HII, cette relation variant toutefois de façon significative entre le disque interne et la périphérie d'une même galaxie. La densité et la dynamique du gaz et des étoiles pourraient influencer de façon significative la stabilité des nuages moléculaires face à l'effondrement gravitationnel. D'une part, l'étendue du disque de régions HII pour cinq galaxies de l'échantillon coïncide avec celle de l'hydrogène atomique. D'autre part, en analysant la stabilité des disques galactiques, on conclue qu'en incluant la densité des étoiles vieilles présentes, on arrive à mieux contraindre le rayon à partir duquel aucune formation d'étoiles ne devrait se produire dans les galaxies.

  15. Matériaux diélectriques à base de K_2Sr4Nb{10}O_{30} présentant des courbes \\varepsilon'_r = f (T) plates avec de hautes constantes diélectriques

    NASA Astrophysics Data System (ADS)

    Tribotté, B.; Desgardin, G.

    1997-06-01

    Type II ferroelectric ceramics are used in multilayers capacitors with high volume capacitance. Among different specifications concerning the variation of the dielectric constant versus temperature, one of the most restrictive class, the X7R one, allows only a variation of ±15 percent of the 25 ^{circ}C value of the permittivity in the wide range, -55 ^{circ}C to +125 ^{circ}C. Previous investigations have proved the interest to mix the niobate K2Sr4Nb{10}O{30}, with a Tetragonal Tungsten Bronze (TTB) structure, with perovskites as minor agents like Pb(Mg{1/3}Nb{2/3})O3, to obtain flat curves \\varepsilon'_r = f (T) with dielectric constant above 6000. To point out the mechanism leading to such curves, the influence of the introduction of different cations like Mg^{2+} or Pb^{2+} in the TTB structure has been studied. In the present work, we show that K2Sr{4}Nb{10}O{30}-based materials, without the presence of perovskite phase from XRD, can also exhibit \\varepsilon'_r= f (T) curves with a flat profile. Les céramiques ferroélectriques de type II sont couramment utilisées dans les condensateurs multicouches à forte capacité volumique. Parmi différentes classes concernant la variation de la constante diélectrique en fonction de la température, une des plus sévères, la X7R, autorise seulement une variation de ±15% de la capacité par rapport à celle à 25 ^{circ}C dans un large domaine de température, de -55 ^{circ}C à +125 ^{circ}C. Des études récentes ont prouvé l'intérêt de mélanger le niobate K2Sr4Nb{10}O{30}, de structure de type Bronze Quadratique de Tungstène (BQT), avec des pérovskites en faible proportion comme Pb(Mg{1/3}Nb{2/3})O3, pour obtenir des courbes plates \\varepsilon'_r = f (T), correspondant à des constantes moyennes superieures à 6000. Pour mettre en évidence le mécanisme conduisant à de telles courbes, nous avons étudié l'influence de l'introduction de différents cations comme Mg^{2+} ou Pb^{2+} dans la structure BQT. Dans ce travail, nous montrons que des matériaux à base de K2Sr4Nb{10}O{30}, sans présence simultanée de phase pérovskite d'après la diffraction des rayons X, peuvent conduire à des courbes \\varepsilon'_r= f (T) à caractère plat.

  16. Synthèses et supraconductivité de monocristaux à base de mercure

    NASA Astrophysics Data System (ADS)

    Pelloquin, D.; Villard, G.; Hardy, V.; Maignan, A.; Raveau, B.

    1998-01-01

    Single crystals (n = 1, 2 and 3) of the Hg_{l-x}M_xBa_2Ca_{n-1}Cu_n O_{2n+2+δ} mercury based cuprates have been grown by using a simple process. The M cations (M = Bi, Cu, Ti) act as stabilizers of the structure which permit to avoid the use of dry box or high gas pressure. The electron microscopy coupled with EDX analyses evidence the regularity of the stacking mode and confirm mixed mercury layers with compositions close to Hg_{0.8} M_{0.2}. Their structural studies based on X-ray diffraction data show a splitting of the oxygen site at the level of the mixed mercury layer. These as-grown superconducting single crystals exhibit T_c close to that of the corresponding pure mercury ceramics. The pinning properties study performed on (Hg_{0.8}Bi_{0.2}) crystals confirms that the n = 1 member is intermediate between the n = 2 and n = 3 members. Moreover, the weak properties of the Hg_{0.6}Ti_{0.4}{-}1223 crystals with regard to the Hg_{0.8}Bi_{0.2}{-}1223 crystals suggest that their different cationic radii Hg/M and their different c-axis values may play a role on these properties. Une méthode de synthèse simple, permettant de faire croître des monocristaux de composition Hg_{l-x}M_xBa_2Ca_{n-1}Cu_n O_{2n+2+δ} (n = 1, 2 et 3) sans utiliser de boîte à gants ou de techniques sous hautes pressions, a été developpée en substituant partiellement le mercure par un cation M (M = Bi, Cu, Ti). Des études par microscopie électronique couplées avec des analyses EDX ont confirmé les modes d'empilement et l'introduction de 1'é1ément M sous la forme de couches mixtes Hg_{0,8}M_{0,2}. Les études structurales réalisées par diffraction de rayons X sur monocristal ont mis en évidence un éclatement du site oxygène lié à la couche mercure. Ces monocristaux, bruts de synthèses, présentent des T_c comparables à celles observées dans les céramiques "tout mercure” correspondantes. L'étude des propriétés d'ancrage des vortex, menée sur les cristaux dopés au bismuth, confirme la position intermédiaire du terme n = 1 par rapport aux termes n = 2 et n = 3. De plus, une comparaison entre les cristaux de type 1223 (n = 3) dopés successivement au titane (Hg_{0,6}Ti_{0,4}{-}1223) et au bismuth (Hg_{0,8}Bi_{0,2}{-}1223) semble mettre en avant les valeurs du rapport Hg/M et du paramètre c sur ces propriétés.

  17. Linking field observations, Landsat and MODIS data to estimate agricultural change in European Russia.

    NASA Astrophysics Data System (ADS)

    de Beurs, K. M.; Ioffe, G.

    2011-12-01

    Agricultural reform has been one of the most important anthropogenic change processes in European Russia that has been unfolding since the formal collapse of the Soviet Union at the end of 1991. Widespread land abandonment is perhaps the most vivid side effect of the reform, even visible in synoptic imagery. Currently, Russia is transitioning into a country with an internal "archipelago" of islands of productive agriculture around cities embedded in a matrix of unproductive, abandoned lands. This heterogeneous spatial pattern is mainly driven by depopulation of the least favorable parts of the countryside, where "least favorable" is a function of fertility, remoteness, and their interaction. In this work we provide a satellite, GIS and field based overview of the current agricultural developments in Russia and look beyond the unstable period immediately following the collapse of the Soviet Union. We apply Landsat images in one of Russia's oblasts to create a detailed land cover map. We then use a logistic model to link the Landsat land cover map with the inter-annual variability in key phenological parameters calculated from MODIS to derive the percent of cropland per 500m MODIS pixel. By evaluating the phenological characteristics of the MODIS curves for each year we determine whether a pixel was actually cropped or left fallow. A comparison of satellite-estimated cropped areas with regional statistics (by rayon) revealed that the satellite estimates are highly correlated with the regional statistics for both arable lands and successfully cropped areas. We use the crop maps to determine the number of times a particular area was cropped between 2002 and 2009 by summing all the years with crops per pixel. This variable provides a good indication about the intensification and de-intensification of the Russian croplands over the last decade. We have visited several rural areas in Russia and we link the satellite data with information acquired through field interviews and photographs. Russian farmers employ a variety of crop-rotation schemes. In the Russian grain belt, the farmers used to be on a seven-year rotation, which typically included only one year of fallow and a variety of grain crops in the remaining six years. Through field interviews and satellite observations we learned that the crop rotation schedules are changing from a seven year crop cycle focused on grain production to a three year crop cycle focused on the production of sunflower which is currently most profitable. In addition, a switch is underway from the dominant growth of spring wheat to stronger reliance on winter wheat which has better growth potential in the area. The number of cropped years, or the complementary number of fallow years, gives an indication of the type of crop cycle that is applied. In addition, drier areas are predicted to reveal more fallow years due to decisions by farm administrators. We will discuss how the ongoing changes represent adaptations to changing climatological and social circumstances.

  18. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gagnon, Jean-Christophe; Theriault, Dany; Guillot, Mathieu

    Purpose: To compare the performance of plastic scintillation detectors (PSD) for quality assurance (QA) in stereotactic radiosurgery conditions to a microion-chamber (IC), Gafchromic EBT2 films, 60 008 shielded photon diode (SD) and unshielded diodes (UD), and assess a new 2D crosshair array prototype adapted to small field dosimetry. Methods: The PSD consists of a 1 mm diameter by 1 mm long scintillating fiber (BCF-60, Saint-Gobain, Inc.) coupled to a polymethyl-methacrylate optical fiber (Eska premier, Mitsubishi Rayon Co., Ltd., Tokyo, Japan). Output factors (S{sub c,p}) for apertures used in radiosurgery ranging from 4 to 40 mm in diameter have been measured.more » The PSD crosshair array (PSDCA) is a water equivalent device made up of 49 PSDs contained in a 1.63 cm radius area. Dose profiles measurements were taken for radiosurgery fields using the PSDCA and were compared to other dosimeters. Moreover, a typical stereotactic radiosurgery treatment using four noncoplanar arcs was delivered on a spherical phantom in which UD, IC, or PSD was placed. Using the Xknife planning system (Integra Radionics Burlington, MA), 15 Gy was prescribed at the isocenter, where each detector was positioned. Results: Output Factors measured by the PSD have a mean difference of 1.3% with Gafchromic EBT2 when normalized to a 10 x 10 cm{sup 2} field, and 1.0% when compared with UD measurements normalized to the 35 mm diameter cone. Dose profiles taken with the PSD crosshair array agreed with other single detectors dose profiles in spite of the presence of the 49 PSDs. Gamma values comparing 1D dose profiles obtained with PSD crosshair array with Gafchromic EBT2 and UD measured profiles shows 98.3% and 100.0%, respectively, of detector passing the gamma acceptance criteria of 0.3 mm and 2%. The dose measured by the PSD for a complete stereotactic radiosurgery treatment is comparable to the planned dose corrected for its SD-based S{sub c,p} within 1.4% and 0.7% for 5 and 35 mm diameter cone, respectively. Furthermore, volume averaging of the IC can be observed for the 5 mm aperture where it differs by as much as 9.1% compared to the PSD measurement. The angular dependency of the UD is also observed, unveiled by an under-response around 2.5% of both 5 and 35 mm apertures. Conclusions: Output Factors and dose profiles measurements performed, respectively, with the PSD and the PSDCA were in agreement with those obtained with the UD and EBT2 films. For stereotactic radiosurgery treatment verification, the PSD gives accurate results compared to the planning system and the IC once the latter is corrected to compensate for the averaging effect of the IC. The PSD provides precise results when used as a single detector or in a dense array, resulting in a great potential for stereotactic radiosurgery QA measurements.« less

  19. Using a colorimeter to develop an intrinsic silicone shade guide for facial prostheses.

    PubMed

    Over, L M; Andres, C J; Moore, B K; Goodacre, C J; Muñoz, C A

    1998-12-01

    To determine if using CIE L*a*b* color measurements of white facial skin could be correlated to those of silicone shade samples that visually matched the skin. Secondly, to see if a correlation in color measurements could be achieved between the silicone shade samples and duplicated silicone samples made using a shade-guide color formula. A color booth was designed according to ASTM specifications, and painted using a Munsell Value 8 gray. A Minolta colorimeter was used to make facial skin measurements on 15 white adults. The skin color was duplicated using custom-shaded silicone samples. A 7-step wedge silicone shade guide was then fabricated, representing the commonly encountered thicknesses when fabricating facial prostheses. The silicone samples were then measured with the Minolta colorimeter. The readings were compared with the previous L*a*b* readings from the corresponding patient's skin measurements, and the relative color difference was then calculated. Silicone samples were fabricated and analyzed for three of the patients to determine if duplication of the visually matched silicone specimen was possible using the silicone color formula, and if the duplicates were visually and colorimetrically equivalent to each other. The color difference Delta E and chromaticity was calculated, and the data were analyzed using a coefficient-of-variation formula expressed by percent. A Pearson Product Moment Correlation Coefficient was performed to determine if a correlation existed between the skin and the silicone samples at the p < or = .05 level. The highest correlation was found in the b* dimension for silicone thicknesses of 1 to 4 mm. For silicone thicknesses of 6 to 10 mm, the highest correlation was found in the L* dimension. All three dimensions had positive correlations (R2 > 0), but only the 1-mm and 4-mm b* readings were very strong. Patient and silicone L*a*b* measurement results showed very little change in the a* axis, while the L* and b* measurements showed more change in their numbers, with changes in depth for all patient silicone samples. Delta E numbers indicated the lowest Delta E at the 1-mm depth and the highest Delta E at the 10-mm depth. All duplicated samples matched their original silicone samples to a degree that visual evaluation could not distinguish any color differences. Using volumetric measurements, a shade guide was developed for all 15 patients. There was good correlation between the patient's colorimeter measurements and the silicone samples, with the b* color dimension the most reproducible, followed by the L* and the a*. Silicone samples at 6, 8, and 10 mm matched the patient the best, and this study showed that silicone samples can be duplicated successfully if a good patient-silicone match is obtained. Rayon flocking fibers and liquid makeup are effective at matching facial prostheses and can be used to develop a simple shade guide for patient application.

  20. Hydrodésazotation de la pyridine sous pression atmosphérique catalysée par des oxynitrures de Ni, Mo, et des oxynitrures mixtes MoNi, MoPNi, AlNi et AlPNi

    NASA Astrophysics Data System (ADS)

    Elkamel, K.; Elidrissi, M.; Yacoubi, A.; Nadiri, A.; Abouarnadasse, S.

    1998-11-01

    Hydrodenitrogenation of pyridine has been realised, under atmospheric pressure, in the presence of oxynitride catalysts of molybdenum, nickel and their solid solutions as well as on mixed catalysts MoNi, MoPNi, AlNi and AlPNi. In all cases, the main reaction products are n-pentane and N-pentylpiperidine, at any conversion. Kinetic results suggest that the conversion of pyridine, on nickel oxynitride, proceeds through successive steps with hydrogenation as rate-limiting. Molybdenum oxynitride and Mo-Ni-N solid solutions tested in the temperature range 500 circC-450 circC, showed a good structural and catalytic stability, but a low catalytic activity. On the other hand, nickel oxynitride catalyst yielded higher activity at much lower temperatures (190 circC-250 circC). X-rays analysis indicates that the used catalyst was entirely reduced to metallic nickel, which is the active phase. Under the same experimental conditions, mixed catalysts are relatively less active but more selective than nickel oxynitride into n-pentane formation. La réaction d'hydrodésazotation de la pyridine a été réalisée, sous pression atmosphérique, en présence de catalyseurs oxynitrures de molybdène, de nickel et leurs solutions solides ainsi que sur les catalyseurs mixtes MoNi, MoPNi, AlNi et AlPNi. Dans tous les cas, les principaux produits de réaction observés sont le n-pentane et la N- pentylpipéridine, quel que soit le taux de conversion. Les résultats cinétiques obtenus en régime intégral, en présence de l'oxynitrure de nickel, suggèrent un schéma réactionnel successif où l'hydrogénation de la pyridine serait l'étape limitante. L'oxynitrure de molybdène et les solutions solides Mo-Ni-N, testés à des températures supérieures ou égales à 500 circC, ont montré une bonne stabilité catalytique et structurale mais une faible activité catalytique. En revanche, l'oxynitrure de nickel présente une activité catalytique plus importante à des températures de réaction beaucoup plus basses (190 circC 250 circC). Cependant, l'analyse aux rayons X du catalyseur usagé, indique qu'il est entièrement réduit à l'état métallique; ceci laisse supposer que le nickel métallique est la phase active. Dans les mêmes conditions expérimentales, les catalyseurs mixtes sont relativement moins actifs que l'oxynitrure de nickel, mais plus sélectifs vis-à-vis de la formation du n-pentane.

  1. Croissance epitaxiale de GaAs sur substrats de Ge par epitaxie par faisceaux chimiques

    NASA Astrophysics Data System (ADS)

    Belanger, Simon

    La situation energetique et les enjeux environnementaux auxquels la societe est confrontee entrainent un interet grandissant pour la production d'electricite a partir de l'energie solaire. Parmi les technologies actuellement disponibles, la filiere du photovoltaique a concentrateur solaire (CPV pour concentrator photovoltaics) possede un rendement superieur et mi potentiel interessant a condition que ses couts de production soient competitifs. La methode d'epitaxie par faisceaux chimiques (CBE pour chemical beam epitaxy) possede plusieurs caracteristiques qui la rendent interessante pour la production a grande echelle de cellules photovoltaiques a jonctions multiples a base de semi-conducteurs III-V. Ce type de cellule possede la meilleure efficacite atteinte a ce jour et est utilise sur les satellites et les systemes photovoltaiques a concentrateur solaire (CPV) les plus efficaces. Une des principales forces de la technique CBE se trouve dans son potentiel d'efficacite d'utilisation des materiaux source qui est superieur a celui de la technique d'epitaxie qui est couramment utilisee pour la production a grande echelle de ces cellules. Ce memoire de maitrise presente les travaux effectues dans le but d'evaluer le potentiel de la technique CBE pour realiser la croissance de couches de GaAs sur des substrats de Ge. Cette croissance constitue la premiere etape de fabrication de nombreux modeles de cellules solaires a haute performance decrites plus haut. La realisation de ce projet a necessite le developpement d'un procede de preparation de surface pour les substrats de germanium, la realisation de nombreuses sceances de croissance epitaxiale et la caracterisation des materiaux obtenus par microscopie optique, microscopie a force atomique (AFM), diffraction des rayons-X a haute resolution (HRXRD), microscopie electronique a transmission (TEM), photoluminescence a basse temperature (LTPL) et spectrometrie de masse des ions secondaires (SIMS). Les experiences ont permis de confirmer l'efficacite du procede de preparation de surface et d'identifier les conditions de croissance optimales. Les resultats de caracterisation indiquent que les materiaux obtenus presentent une tres faible rugosite de surface, une bonne qualite cristalline et un dopage residuel relativement important. De plus, l'interface GaAs/Ge possede une faible densite de defauts. Finalement, la diffusion d'arsenic dans le substrat de germanium est comparable aux valeurs trouvees dans la litterature pour la croissance a basse temperature avec les autres procedes d'epitaxie courants. Ces resultats confirment que la technique d'epitaxie par faisceaux chimiques (CBE) permet de produire des couches de GaAs sur Ge de qualite adequate pour la fabrication de cellules solaires a haute performance. L'apport a la communaute scientifique a ete maximise par le biais de la redaction d'un article soumis a la revue Journal of Crystal Growth et la presentation des travaux a la conference Photovoltaics Canada 2010 . Mots-cles : Epitaxie par jets chimiques, Chemical beam epitaxy, CBE, MOMBE, Germanium, GaAs, Ge

  2. Nanoparticules d'or: De l'imagerie par resonance magnetique a la radiosensibilisation

    NASA Astrophysics Data System (ADS)

    Hebert, Etienne M.

    Cette thèse approfondit l'étude de nanoparticules d'or de 5 nm de diamètre recouvertes de diamideéthanethioldiethylènetriaminepentacétate de gadolinium (DTDTPA:Gd), un agent de contraste pour l'imagerie par résonance magnétique (IRM). En guise de ciblage passif, la taille des nanoparticules a été contrôlée afin d'utiliser le réseau de néovaisseaux poreux et perméable des tumeurs. De plus les tumeurs ont un drainage lymphatique déficient qui permet aux nanoparticules de demeurer plus longtemps dans le milieu interstitiel de la tumeur. Les expériences ont été effectuées sur des souris Balb/c femelles portant des tumeurs MC7-L1. La concentration de nanoparticules a pu être mesurée à l'IRM in vivo. La concentration maximale se retrouvait à la fin de l'infusion de 10 min. La concentration s'élevait à 0.3 mM dans la tumeur et de 0.12 mM dans le muscle environnant. Les nanoparticules étaient éliminées avec une demi-vie de 22 min pour les tumeurs et de 20 min pour le muscle environnant. Les nanoparticules ont été fonctionnalisées avec le peptide Tat afin de leur conférer des propriétés de ciblage actif La rétention de ces nanoparticules a ainsi été augmentée de 1600 %, passant d'une demi-vie d'élimination de 22 min à 350 min. La survie des souris a été mesurée à l'aide de courbes Kaplan-Meier et d'un modèle mathématique évalue l'efficacité de traitements. Le modèle nous permet, à l'aide de la vitesse de croissance des tumeurs et de l'efficacité des traitements, de calculer la courbe de survie des spécimens. Un effet antagoniste a été observé au lieu de l'effet synergétique attendu entre une infusion de Au@DTDTPA:Gd et l'irradiation aux rayons X. L'absence d'effet synergétique a été attribuée à l'épaisseur du recouvrement de DTDTPA:Gd qui fait écran aux électrons produits par l'or. De plus, le moyen d'ancrage du recouvrement utilise des thiols qui peuvent s'avérer être des capteurs de radicaux. De plus, contrairement a ce qui était escompté, un effet chimiothérapeutique de ces nanoparticules a été observé in vitro et in vivo. Par contre, le mécanisme précis de cet effet est encore à être expliquer, mais on sait déjà que les nanoparticules d'or affectent les fonctions des macrophages ainsi que l'angiogenèse. MOTS-CLÉS : Radiosensibilisateur, Nanoparticules d'or, Agent de contraste pour l'IRM, Électrons de basses énergies, Kaplan-Meier, Effet chimiothérapeutique.

  3. Elaboration de revetements nanocomposites avec des proprietes superhydrophobes, semi-conductrices et photocatalytiques

    NASA Astrophysics Data System (ADS)

    Madidi, Fatima Zahra

    Les lignes aeriennes de transport et de distribution de l'energie electrique sont souvent exposees a diverses contraintes. Parmi celles-ci, la pollution des isolateurs constitue l'un des facteurs de premiere importance dans la fiabilite du transport d'energie. En effet, la presence de pollution sur les isolateurs lorsqu'elle est humidifiee entraine la diminution de leur performance electrique en favorisant l'apparition d'arcs de contournement. De telles pannes peuvent parfois causer des impacts socioeconomiques importants. Par ailleurs, le developpement de nouveaux revetements pour ces isolateurs peut s'averer un moyen efficace pour les proteger contre l'apparition de l'arc de contournement. Les revetements superhydrophobes ont fait l'objet de nombreuses etudes au cours de ces dernieres annees. Ces surfaces sont preparees en combinant une rugosite nano-microstructuree avec une faible energie de surface. En outre, de telles surfaces ont de nombreuses applications si elles sont durables et n'ont pas d'effets nocifs sur l'environnement. L'objectif principal de la presente etude vise d'abord l'elaboration de revetements superhydrophobes, puis l'etude de leur duree de vie, leurs proprietes dielectriques et photocatalytiques. Une grande variete de materiaux a faible energie de surface peuvent etre utilises pour le developpement de ces revetements. Dans cette recherche, le caoutchouc de silicone (CS) est employe car il presente de nombreuses proprietes, notamment une forte hydrophobie, une resistance aux rayonnements ultraviolets, et une bonne tenue au feu sans degagement de produits toxiques. Toutefois, le point faible de ces materiaux est la degradation de leurs proprietes hydrophobes. Afin d'ameliorer certaines proprietes du caoutchouc de silicone, des nanoparticules seront additionnees au polymere de base. La technique d'elaboration des revetements consiste a ajouter des nanoparticules de dioxyde de titane (TiO2) au polymere de base, par des methodes ayant un potentiel d'applications industrielles. Les parametres d'elaboration ont ete optimises afin d'obtenir des revetements stables presentant des angles de contact eleves avec des gouttelettes d'eau et de faibles hysteresis. Apres avoir obtenu des surfaces superhydrophobes, des tests de stabilite ont ete effectues dans des conditions de vieillissement accelere tels que l'immersion dans des solutions aqueuses avec differents pH et conductivites ou la degradation par rayonnement UV. Les resultats obtenus ont montre que l'ajout de nanoparticules de dioxyde de titane au caoutchouc de silicone permet d'ameliorer l'hydrophobie et la stabilite de ce polymere. Les revetements superhydrophobes obtenus ont pu maintenir leur superhydrophobicite apres plusieurs jours d'immersion dans differentes solutions aqueuses. Ils presentent aussi une bonne stabilite lorsqu'ils sont exposes aux rayons UV ainsi qu'une stabilite mecanique. De plus, on a pu developper des revetements nanocomposites et microcomposites avec de bonnes proprietes dielectriques. L'etude des proprietes photocatalytiques des revetements superhydrophobes ont montre que l'adsorption des molecules reactives (polluants) sur la surface du catalyseur (TiO2) est le parametre cle de l'activite photocatalytique. L'augmentation de la concentration de TiO2 conduit a une diminution de la concentration du polluant et par consequent a un excellent rendement photocatalytique.

  4. Complexation des acides aminés basiques arginine, histidine et lysine avec l'ADN plasmidique en solution aqueuse : participation à la capture de radicaux sous irradiation X à 1,5 keV

    NASA Astrophysics Data System (ADS)

    Tariq Khalil, Talat; Taillefumier, Baptiste; Boulanouar, Omar; Mavon, Christophe; Fromm, Michel

    2016-09-01

    L'environnement chimique de l'ADN en situation biologique est complexe notam-ment en raison de la présence d'histones, protéines nucléaires, associées en quantité approximativement égales à l'ADN pour former la chromatine. Les histones possèdent de nombreux radicaux basiques arginine et lysine chargés positivement et dont la majorité se trouve sur les chaînes émergentes, l'ADN présente quant à lui des charges négatives sur ses groupements phosphates localisés tout au long de la double hélice. Dans cette étude, la complexité de la structure de la chromatine nucléaire est dans un premier temps mimée en solution aqueuse par la formation de complexes entre un ADN plasmidique sonde et les trois acides aminés basiques, Arg, His, Lys, qui, mis à part His, sont protonés au pH physiologique. Ces acides aminés libres en solution sont réputés être des capteurs efficaces de radicaux libres, notamment pour le radical hydroxyle, conférant ainsi un pouvoir protecteur vis-à-vis des effets indirects sur l'ADN en situation d'exposition aux rayonnements ionisants. A concentration fixée, les capacités de capture des acides aminés libres, σ, pour le radical hydroxyle sont typiquement les suivantes σHis ≈σArg > σLys (σLys ≈ 0,1 × σArg). Nous avons mesuré les taux de cassures simple brin par plasmide et par Gray (χ) lors d'expositions de solutions aqueuses de complexes [acide aminé - ADN plasmidique] aux rayons X ultra-mous (1,5 keV). A concentrations égales, les trois acides aminés complexés et présents en large excès ne manifestent pas une capacité de protection de l'ADN proportionnelle à leur capacité de capture libre et en solution ; on trouve en effet des taux de cassures dans l'ordre suivant χHis > χArg > χLys (χLys ≈ 0,01 χArg). Après avoir détaillé le mode opératoire de ces mesures, nous analyserons sur des bases bibliographiques, les modes spécifiques d'interaction des acides aminés basiques avec l'ADN. La spécificité des liaisons de l'arginine avec l'ADN et plus particulièrement sa propension à être un ligand bidentate qui se lie aux bases (principalement G) de l'ADN nous permet d'expliquer les taux de cassures simple brin particulièrement élevés observés avec Arg. Un mécanisme de transfert de radical intermoléculaire est suggéré pour Arg. Un raisonnement globalement similaire peut être tenu pour la lysine. Pour l'histidine, nous suggérons quelques voies possibles qui conduiraient à expliquer les taux de cassure anormalement élevés observés, mais cela demandera des expériences complémentaires.

  5. Hot Structure Control Surface Progress for X-37 Technology Development Program

    NASA Technical Reports Server (NTRS)

    Valentine, P. G.; Meyer, David L. (Editor); Snow, Holly (Editor)

    2004-01-01

    The NASA Marshall Space Flight Center (MSFC) has been leading the development of technologies that will enable the development, fabrication, and flight of the automated X-37 Orbital Vehicle (OV). With the Administration s recent announcement of the Vision for Space Exploration, NASA placed the X-37 OV design on hold while developing detailed requirements for a Crew Exploration Vehicle, but has continued funding the development of high-risk, critical technologies for potential future space exploration vehicle applications. Hot Structure Control Surfaces (HSCS) technology development is one of the high-priority areas being funded at this time. The goal of HSCS research is to mitigate risk by qualifying the lightest possible components that meet the stringent X-37 OV weight and performance requirements, including Shuttle-type reen- try environments with peak temperatures of 2800 OF. The small size of the X-37 OV (25.7-feet long and 14.9-foot wingspan) drives the need for advanced HSCS because the vehicle's two primary aerodynamic surfaces, the flaperons and ruddervators, have thicknesses ranging from approximately 5 in. down to 1 in. Traditional metallic or polymer-matrix composites covered with tile or blanket thermal protection system (TPS) materials cannot be used as there is insufficient volume to fabricate such multi-component structures. Therefore, carbon-carbon (C-C) and carbodsilicon-carbide (C-SiC) composite HSCS structures are being developed in parallel by two teams supporting the X-37 prime contractor (The Boeing Company). The Science Applications International Coy. (SAIC) and Carbon-Carbon Advanced Technologies, Inc. (C-CAT) team is developing the C-C HSCS, while the General Electric Energy Power Systems Composites (GE-PSC) and Materials Research and Design (MRD) team is developing the C-SiC HSCS. These two teams were selected to reduce the high level of risk associated with developing advanced control surface components. They have continued HSCS development work as part of the X-37 critical technology development contract. The SAIC/C-CAT team is using Advanced Carbon-Carbon (ACC) because its fabrication is very similar to the process used for Space Shuttle Reinforced Carbon-Carbon fabrication, including the Sic-based pack cementation conversion coating systems using with both materials. ACC was selected over RCC because it has much higher tension and compressions strengths, and because T-300 fiber is readily available, whereas RCC rayon fiber is no longer manufactured. The GE-PSC/MRD team is using a T-300 fiber-reinforced Sic matrix composite material densified by chemical vapor infiltration. The C-Sic material has an Sic-based environmental barrier coating. Major accomplishments have been made over the past year by both HSCS teams. C-C and C- SiC flaperon subcomponents, which are truncated full-scale versions of flight hardware, have been fabricated and are undergoing testing at the NASA Dryden Flight Research Center, NASA Langley Research Center, and U.S. Air Force Research Laboratory. By the end of 2004, ruddervator subcomponents also will be delivered and tested. As NASA moves forward in realizing the Vision for Space Exploration, it will continue to invest in advanced research and development aimed at making new generations of spacecraft safer, more reliable, and more affordable. The X-37 HSCS effort ultimately will benefit the Agency's vision and mission.

  6. Determination des Parametres Atmospheriques des Etoiles Naines Blanches de Type DB

    NASA Astrophysics Data System (ADS)

    Beauchamp, Alain

    1995-01-01

    Les etoiles naines blanches dont les spectres visibles sont domines par des raies fortes d'helium neutre sont subdivisees en trois classes, DB (raies d'helium neutre seulement), DBA (raies d'helium neutre et d'hydrogene) et DBZ (raies d'helium neutre et d'elements lourds). Nous analysons trois echantillons de spectres observes de ces types de naines blanches. Les echantillons consistent, respectivement, de 48 spectres dans le domaine du visible (3700-5100 A). 24 dans l'ultraviolet (1200-3100 A) et quatre dans la partie rouge du visible (5100-6900) A). Parmi les objets de l'echantillon visible, nous identifions quatre nouvelles DBA, ainsi que deux nouvelles DBZ, auparavant classees DB. L'analyse nous permet de determiner spectroscopiquement les parametres atmospheriques, soit la temperature effective, la gravite de surface, ainsi que l'abondance relative de l'hydrogene, N(H)/N(He), dans le cas des DBA. Pour les objets plus chauds que ~15,000 K, la gravite de surface determinee est fiable, et nous obtenons les masses stellaires avec une relation masse -rayon theorique. Les exigences propres a l'analyse de ces objets ont requis d'importantes ameliorations dans la modelisation de leurs atmospheres et distributions de flux de radiation emis par ces derniers. Nous avons inclus dans les modeles d'atmospheres, pour la premiere fois a notre connaissance, les effets dus a la molecule He_sp{2 }{+}, ainsi que l'equation d'etat de Hummer et Mihalas (1988), qui tient compte des perturbations entre particules dans le calcul des populations des differents niveaux atomiques. Nous traitons la convection dans le cadre de la theorie de la longueur de melange. Trois grilles de modeles d'atmospheres a l'ETL (equilibre thermodynamique local) ont ete produites, pour un ensemble de temperatures effectives, gravites de surface et abondances d'hydrogene couvrant les proprietes des etoiles de nos echantillons; elles sont caracterisees par differentes parametrisations appelees, respectivement, ML1, ML2 et ML3, de la theorie de longueur de melange. Nous avons calcule une grille de spectres synthetiques avec les memes parametrisations que la grille de modeles d'atmospheres. Notre traitement de l'elargissement des raies de l'helium neutre a ete ameliore de facon significative par rapport aux etudes precedentes. D'une part, nous tenons compte de l'elargissement des raies produit par les interactions entre l'emetteur et les particules neutres (elargissements par resonance et de van der Waals) en plus de celui par les particules chargees (elargissement Stark). D'autre part, nous avons calcule nous-memes les profils Stark avec les meilleures theories d'elargissement disponibles pour la majorite des raies observees; ces profils depassent en qualite ce qui a ete publie jusqu'a ce jour. Nous avons calcule la distribution de masse des etoiles DB plus chaudes que 15,000 K. La distribution de masse des DB est tres etroite, avec environ les trois quarts des etoiles incluses dans l'intervalle 0.55-0.65 Modot. La masse moyenne des etoiles DB est de 0.58 M_⊙ avec sigma = 0.07. La difference principale entre les distributions de masse des DB et DA est la faible proportion de DB dans les ailes de la distribution, ce qui implique que les DA moins massives que ~0.4 M odot et plus massives que ~0.8 M_⊙ ne se convertissent pas en DB. Les objets les plus massifs de notre echantillon sont de type DBA, ce qui suggere que la masse elevee favorise la visibilite de l'hydrogene. (Abstract shortened by UMI.).

  7. Etude de l'impact de la valorisation energetique de pneus hors d'usage, dans une cimenterie, sur les emissions gazeuses par modelisation de la dispersion atmospherique

    NASA Astrophysics Data System (ADS)

    Bredin, Nathalie

    La génération incéssante de déchets nécessite le développement de nouvelles technologies, telle que la valorisation énergétique, pour en disposer. Une filière appropriée pour valoriser énergétiquement les déchets est le procédé cimentier. L'industrie du ciment est une des grandes consommatrices d'énergie. La température nécessaire à la préparation du ciment se situe aux environs de 1450°C pour faire réagir la matière première (cru) qui est sous forme poudreuse et constituée principalement de roches calcaires, argileuses, schisteuses,... Les gaz de combustion ont un long temps de résidence dans les fours. De plus, le mode de fonctionnement des fours est responsable d'un effet de lessivage des gaz acides par le cru alcalin. Ces propriétés font du procédé cimentier un bon candidat pour la valorisation énergétique des déchets. Les déchets interessants pour les cimenteries sont, entre autres, les huiles usées, les solvants usés et les pneus usés qui ont un pouvoir calorifique équivalent à celui du charbon. Les rejets à l'atmosphère des cimenteries sont principalement des émissions gazeuses. Ainsi, l'impact de la valorisation de pneus usés sur les émissions gazeuses de la cimenterie Saint-Laurent de Joliette a été étudié, à l'aide de l'outil qu'est la modélisation de la dispersion atmosphérique. Le modèle utilisé ISC-ST2, Industrial Source Complex-Short Term, est de type gaussien. L'analyse des concentrations maximales horaires et moyennes sur différentes périodes de temps (1 heure, 8 heures, ..., 1 an) des émissions gazeuses dans l'air ambiant montre que celles-ci sont en deçà des normes émises par le gouvernement québécois et par la Communauté Urbaine de Montréal. L'étude de la distribution géographique des polluants, d'après les concentrations annuelles, dans un rayon de 5 km autour de la cimenterie montre que le fait d'utiliser des pneus comme combustible de substitution n'a qu'un faible impact sur la concentration des contaminants au niveau du sol. L'étude du modèle gaussien de dispersion a permis de mettre au point un nouvel outil: la corrélation existant entre les concentrations latérales et verticales des polluants dans le panache. Cet outil utilisé pour étudier les schémas de dispersion atmosphérique de Turner en milieu rural, et de Briggs en milieux urbain et rural, montre que, en milieu rural, le schéma de dispersion proposé par Briggs présente une dispersion plus importante que celui de Turner pour les classes neutres et instables et moins importantes pour les classes stables. La comparaison des schémas de Briggs (rural et urbain) confirme que la dispersion en milieu urbain est plus importante qu'en milieu rural.

  8. Micromechanical simulation of damage progression in carbon phenolic composites

    NASA Technical Reports Server (NTRS)

    Slattery, Kerry T.

    1993-01-01

    Carbon/phenolic composites are used extensively as ablative insulating materials in the nozzle region of solid rocket motors. The current solid rocket motor (RSRM) on the space shuttle is fabricated from woven rayon cloth which is carbonized and then impregnated with the phenolic resin. These plies are layed up in the desired configuration and cured to form the finished part. During firing, the surface of the carbon/phenolic insulation is exposed to 5000 F gases from the rocket exhaust. The resin pyrolizes and the material chars to a depth which progresses with time. The rate of charring and erosion are generally predictable, and the insulation depth is designed to allow adequate safety margins over the firing time of the motor. However, anomalies in the properties and response of the carbon/phenolic materials can lead to severe material damage which may decrease safety margins to unacceptable levels. Three macro damage modes which were observed in fired nozzles are: ply lift, 'wedge out', and pocketing erosion. Ply lift occurs in materials with plies oriented nearly parallel to the surface. The damage occurs in a region below the charred material where material temperatures are relatively low - about 500 F. Wedge out occurs at the intersection of nozzle components whose plies are oriented at about 45 deg. The corner of the block of material breaks off along a ply interface. Pocketing erosion occurs in material with plies oriented normal to the surface. Thermal expansion is restrained in two directions resulting in large tensile strains and material failure normal to the surface. When a large section of material is removed as a result of damage, the insulation thickness is reduced which may lead to failure of the nozzle due to excessive heating of critical components. If these damage events cannot be prevented with certainty, the designer must increase the thickness of the insulator thus adding to both weight and cost. One of the difficulties in developing a full understanding of these macro damage mechanisms is that the loading environment and the material response to that environment are extremely complex. These types of damage are usually only observed in actual motor firings. Therefore, it is difficult and expensive to evaluate the reliability of new materials. Standard material tests which measure mechanical and thermal properties of test specimens can only provide a partial picture of how the material will respond in the service environment. The development of the ANALOG test procedure which can combine high heating rates and mechanical loads on a specimen will improve the understanding of the interactive effects of the various loads on the system. But a mechanistic model of material response which can account for the heterogeneity of the material, the progression of various micromechanical damage mechanisms, and the interaction of mechanical and thermal stresses on the material is required to accurately correlate material tests with response to service environments. A model based on fundamental damage mechanisms which is calibrated and verified under a variety of loading conditions will provide a general tool for predicting the response of rocket nozzles. The development of a micromechanical simulation technique was initiated and demonstrated to be effective for studying across-ply tensile failure of carbon/phenolic composites.

  9. 42 years of continuous observations of the Solar 1 diameter from 1974 to 2015 - What do they forecast.

    NASA Astrophysics Data System (ADS)

    Humberto Andrei, Alexandre; Penna, Jucira; Boscardin, Sergio; Papa, Andres R. R.; Garcia, Marcos Antonio; Sigismondi, Costantino

    2016-07-01

    Several research groups in the world developed observational programs for the Sun in order to measure its apparent diameter over time with dedicated instruments, called solar astrolabes, since 1974. Their data have been gathered in several observing stations connected in the R2S3 (Réseau de Suivi au Sol du Rayon Solaire) network and through reciprocal visits and exchanges: Nice/Calern Observatoire/France, Rio de Janeiro Observatório Nacional/Brazil, Observatório de São Paulo IAGUSP/Brazil, Observatório Abrahão de Moraes IAGUSP/Brazil, Antalya Observatory/Turkey, San Fernando/Spain. Since all the optics and data treatment of the solar astrolabes was the same, from the oldest, with a single fixed objective prism, to the newest, with an angle variable objective prism and digital image acquisition, their results could be put together. Each instrument had its own density filter with a prismatic effect responsible for a particular shift. Thus, identical data gathering and just a different prismatic shift, enabled to reconcile all those series by using the common stretches and derive a single additive constant to place each one onto a common average. By doing so, although the value itself of the ground observed solar diameter is lost, its variations are determined over 35 years. On the combined series of the ground observed solar diameter a modulation with the 11 years main solar cycle is evident. However when such modulation is removed, both from the solar diameter compound series and from the solar activity series (as given by the sunspots count), a very strong anticorrelation is revealed. This suggested a larger diameter for the forthcoming cycles. This was very well verified for solar cycle 23, and correctly forecasted for cycle 24,in a behavior similar to that on the Minima of Dalton and Maunder. The ground monitoring keeps being routinely followed at Observatório Nacional in Rio de Janeiro, now using the Solar Heliometer, specially built to this end . The Heliometer has the same focal length and aperture of the earlier solar astrolabes, and the diameter determination uses the same physical and mathematical definition of the solar limb. Therefore the same robust, no-hypothesis, simple combination by an adding constant, can be used to include the Heliometer measurements along the previous long, continuous series. As a result the series of measurements of the variation of the solar diameter reaches 42 years, and covers also the solar cycle 24. In this paper we review all the individual series chief elements, as well as the calculation and values of the adding constants. We show the earlier comparison that lead to an anticorrelation at 0.867 to the solar activity record, when the 11 years modulation is expurgate, and exhibits an impressively accurate description of cycle 23. On the strength of such successful analysis we employ the new longer series to discuss the current solar cycle 24 and forecast for the following solar cycle 25. We thus advocate in favor of continued and continuous ground measurements of the solar diameter, on the usefulness of making these results available to the scientific community at large, and on the matter-of-fact, real variations of the solar diameter on long term time periods and/or local places on the Sun, in this case possibly associated to major magnetism driven solar transients.

  10. Préface

    NASA Astrophysics Data System (ADS)

    Schober, Helmut; Fischer, Henry; Leclercq-Hugeux, Françoise

    2003-09-01

    L'École Thématique “Structure et Dynamique des Systèmes Désordonnés” [1] s'inscrit dans le cadre des écoles organisées sous l'impulsion de la Société Française de la Neutronique (SFN). Elle s'est deroulée en mai 2002 sur la Presqu'île de Giens (Var) en première partie des 11émes Journées de la Diffusion Neutronique. L'Édition de ces cours constitue ainsi le cinquième ouvrage introduisant les techniques neutroniques et leurs apports à differentes thématiques [2]. Le désordre est un facteur déterminant pour pratiquement toutes les propriétés des matériaux. Il est inhérent dans les matériaux amorphes ou liquides, mais il détermine également les propriétés mécaniques et électroniques d'autres composés d'importance technologique comme les matériaux métalliques, dont l'aspect “désordonné” est moins évident. Le désordre enfin joue un rôle essentiel dans tout ce que touche à la vie. En fait, il est difficile d'imaginer des systèmes, à part quelques exceptions rares comme l'hélium ou le silicium de haute pureté, où il n'y ait pas de désordre. En dehors de cet aspect pratique, la description scientifique du désordre atomique pose toujours des problèmes fondamentaux faute de concepts pertinents. Une des tâches importantes du scientifique ou de l'ingenieur est de préciser quel genre de désordre existe à une échelle d'espace et de temps donnée. Un materiau peut très bien être homogène à l'échelle atomique et présenter des défauts ou des hétrogéneité visibles à l'œil et inversement. De même, un système désordonné à un instant donné, peut apparaître ordonné si on moyenne dans le temps. Les techniques de diffusion des neutrons sont idéales pour aborder ces questions. Les neutrons sondent directement les noyaux et ont à la fois des longueurs d'ondes proches des distances inter atomiques et des énergies avoisinant celles des excitations élémentaires de la matière condensée. Ils permettent ainsi une observation directe et non-destructive des positions et des mouvements atomiques. La gamme des distances et des temps sondés par les neutrons autorisent aussi bien de suivre le mouvement des atomes à l'échelle inter atomique que l'évolution d'une structure soit mésoscopique soit macroscopique sur des temps de moins d'une picoseconde à plusieurs heures. La gamme des techniques de diffusion utilisées pour couvrir un tel champ d'application est naturellement très large : différents types de diffractomètres permettent des études de structure atomique trés pointue et résolue dans le temps. Les spectromètres nous donnent accès à la dynamique d'une dizaine de femto- à plusieurs nanosecondes. La diffusion aux petits angles, la reflectomètrie et finalement la tomographie nous permettent de regarder la structure et la dynamique d'objets plus grands. Il était illusoire de prétendre couvrir la totalité des systèmes désordonnés et l'ensemble des techniques de diffusion neutronique pertinentes au cours d'une école de 3 jours. Nous avons donc été amené à nous concentrer sur les liquides, les verres, les cristaux plastiques et les polymères. Ce choix s'est imposé par le souhait d'introduire les concepts de base, en acceptant de sacrifier certains domaines d'applications. Il va de soi que l'étude approfondie de systèmes mettant en jeu plusieurs échelles de distance (structure moléculaire, portée des corrélations entre les molécules) et de temps (relaxations caractéristiques des divers phenomènes dynamiques selon leur extension spatiale) implique une pluralité de techniques expérimentales, complémentaires des différentes techniques neutroniques disponibles. Un des objectifs de cette école etait donc de préciser les domaines de pertinence des différentes techniques neutroniques disponibles en en situant la complémentarité avec d'autres approches instrumentales (diffraction des rayons X, EXAFS, RMN, etc.). Enfin la confrontation avec les résultats obtenus par simulation et modélisation numérique est essentielle à la compréhension des processus élémentaires dans ces systèmes complexes. En première partie de cet ouvrage, on trouvera une description géntrale des systèmes désordonnés et une introduction aux techniques de diffusion de neutrons. Pour la partie concernant la structure, une revue des techniques de diffraction est suivie par des applications à des systèmes de complexité croissante (liquides métalliques simples, alliages liquides, semiconducteurs fondus, solutions aqueuses, verres d'oxydes). L'apport des méthodes de variation de longueur de diffusion (substitution isotopique pour les mesures aux neutrons, diffusion anomale des rayons X ou combinaison de ces deux techniques) permet la détermination des facteurs de structures partiels. Pour la dynamique, on a privilégié une approche introduisant progressivement le désordre en passant des solides aux liquides. Le concept de diffusion puis les particularités dynamiques des verres sont ensuite présentés et illustrés par des exemples concrets. Enfin la dernière partie est consacrée à la simulation numérique des propriétés dynamiques des verres et des liquides et à la modélisation de la structure par méthode de Monte Carlo inverse (RMC) à partir de l'ensemble des données expérimentales existant pour un système donné. La communauté française a joué un rôle important dans le développement des techniques neutroniques dédites à l'étude des systèmes désordonnés et y a acquis une competence reconnue. Nous avons essayé, dans cet ouvrage, de privilégier les aspects pédagogiques des cours, pour les rendre accessibles aux scientifiques francophones non spécialistes en diffusion des neutrons. Nous saluons ici l'effort de rédaction, en langue française, des différents intervenants et souhaitons que cet ouvrage puisse participer à la formation et au renouvellement de la communauté neutronique française. Helmut Schober et Henry Fischer (Editeurs scientifiques) Françoise Leclercq-Hugeux (Présidente de la SFN)

  11. Noble internal transport barriers and radial subdiffusion of toroidal magnetic lines

    NASA Astrophysics Data System (ADS)

    Misguich, J. H.; Reuss, J.-D.; Constantinescu, D.; Steinbrecher, G.; Vlad, M.; Spineanu, F.; Weyssow, B.; Balescu, R.

    2003-11-01

    Internal transport barriers (ITB's) observed in tokamaks are described by a purely magnetic approach. Magnetic line motion in toroidal geometry with broken magnetic surfaces is studied from a previously derived Hamiltonian map in situation of incomplete chaos. This appears to reproduce in a realistic way the main features of a tokamak, for a given safety factor profile and in terms of a single parameter L representing the amplitude of the magnetic perturbation. New results are given concerning the Shafranov shift as function of L. The phase space (psi ,θ ) of the "tokamap" describes the poloidal section of the line trajectories, where psi is the toroidal flux labelling the surfaces. For small values of L, closed magnetic surfaces exist (KAM tori) and island chains begin to appear on rational surfaces for higher values of L, with chaotic zones around hyperbolic points, as expected. Island remnants persist in the chaotic domain for all relevant values of L at the main rational q-values. Single trajectories of magnetic line motion indicate the persistence of a central protected plasma core, surrounded by a chaotic shell enclosed in a double-sided transport barrier: the latter is identified as being composed of two Cantori located on two successive “most-noble” numbers values of the perturbed safety factor, and forming an internal transport barrier (ITB). Magnetic lines which succeed to escape across this barrier begin to wander in a wide chaotic sea extending up to a very robust barrier (as long as Lprecsim 1) which is identified mathematically as a robust KAM surface at the plasma edge. In this case the motion is shown to be intermittent, with long stages of pseudo-trapping in the chaotic shell, or of sticking around island remnants, as expected for a continuous time random walk. For values of Lsucceq 1, above the escape threshold, most magnetic lines succeed to escape out of the external barrier which has become a permeable Cantorus. Statistical analysis of a large number of trajectories, representing the evolution of a bunch of magnetic lines, indicate that the flux variable psi asymptotically grows in a diffusive manner as (L2t) with a L2 scaling as expected, but that the average radial position rm(t) asymptotically grows as (L2t)^{1/4} while the mean square displacement around this average radius asymptotically grows in a subdiffusive manner as (L2t)^{1/2}. This result shows the slower dispersion in the present incomplete chaotic regime, which is different from the usual quasilinear diffusion in completely chaotic situations. For physical times t_{\\varphi } of the order of the escape time defined by xm(t_{\\varphi })sim 1, the motion appears to be superdiffusive, however, but less dangerous than the generally admitted quasi-linear diffusion. The orders of magnitude of the relevant times in Tore Supra are finally discussed. Barrières internes de transport " nobles " et sous-diffusion radiale des lignes magnétiques toroïdales Les barrières internes de transport observées dans les tokamaks sont décrites ici dans une approche purement magnétique. Le mouvement des lignes magnétiques en géométrie toroïdale avec brisure des surfaces magnétiques est étudié à partir d'une application hamiltonienne "tokamap" développée précédemment en situation de chaos incomplet, et dans laquelle le "temps" est représenté par la coordonnée toroïdale. Cette application reproduit de façon réaliste les principales caractéristiques d'un tokamak, pour un profil donné du facteur de sécurité q, et en terme d'un seul paramètre L représentant l'amplitude de la perturbation magnétique. On obtient des résultats nouveaux concernant le déplacement de Shafranov en fonction de L. L'espace des phases (psi,θ) du "tokamap" décrit la section poloïdale des trajectoires des lignes, où psisim r^2 est le flux toroïdal caractérisant les surfaces magnétiques (proportionnel au carré du rayon r de cette surface). Pour de faibles valeurs de L, des surfaces magnétiques fermées existent (tores de KAM) et des chaînes d'îlots commencent à apparaître sur les surfaces rationnelles pour des valeurs de L supérieures, avec, comme attendu, des zones chaotiques autour des points hyperboliques. Des résidus d'îlots magnétiques persistent dans le domaine chaotique pour toutes les valeurs de L, sur les surfaces caractérisées par les principales valeurs rationnelles de q. Des trajectoires individuelles de ligne magnétique indiquent la persistance d'un cœur protégé au sein du plasma, entouré d'une couche chaotique, incluse dans une double barrière de transport : celle-ci est composée de deux Cantori situés sur deux valeurs successives du facteur de sécurité perturbé que l'on a pu identifier comme étant les nombres "les plus nobles", formant ainsi une barrière de transport interne. Les lignes magnétiques qui réussissent à s'échapper à travers cette barrière commencent à voyager dans une vaste mer chaotique qui s'étend jusqu'à une barrière très robuste (tant que Lprecsim 1) qui a été identifiée mathématiquement comme étant une surface KAM robuste au bord du plasma. Dans ce cas le mouvement observé est intermittent, avec de longues périodes de pseudo-piégeage dans la couche chaotique, ou du collage (sticking) autour des îlots résiduels, comme attendu pour une marche aléatoire en temps continu. Pour des valeurs de Lsucceq 1, au-dessus du seuil d'échappement, la plupart des lignes magnétiques parviennent à s'échapper à travers la barrière externe qui est devenue un Cantorus perméable. L'analyse statistique d'un grand nombre de trajectoires, représentant l'évolution d'un faisceau de lignes magnétiques, indique qu'en moyenne la variable de flux psi croît asymptotiquement de manière diffusive (comme L^2t) avec une loi d'échelle en L^2 comme attendu, mais avec une position radiale moyenne r_m(t) croissant asymptotiquement comme (L^2t)^{1/4}, tandis que le déplacement quadratique moyen autour de ce rayon moyen croît asymptotiquement de manière sous-diffusive comme (L^2t)^{1/2}. Ce résultat indique une dispersion plus lente dans le cas étudié d'un régime de chaos incomplet, qui est différente de la diffusion quasi-linéaire en situation de chaos complet. Pour des temps physiques t_{\\varphi} de l'ordre du temps d'échappement, défini par r_m(t_{\\varphi}) sim 1, le mouvement apparaît comme super-diffusif, mais cependant moins " dangereux " que la diffusion quasi-linéaire généralement admise. On discute finalement les ordres de grandeur des temps caractéristiques dans le tokamak TORE SUPRA.

  12. Le pôle de métrologie de SOLEIL

    NASA Astrophysics Data System (ADS)

    Idir, M.; Brochet, S.; Delmotte, A.; Lagarde, B.; Mercere, P.; Moreno, T.; Polack, F.; Thomasset, M.

    2006-12-01

    Le Pôle de METROLOGIE de SOLEIL a pour objet de créer sur le synchrotron SOLEIL, une plateforme constituée : - une ligne de lumière utilisant le rayonnement synchrotron (métrologie dite à la longueur d'onde) - d'un laboratoire de métrologie associé (métrologie dite ll classique gg ) Ces deux types de Métrologie sont l'une et l'autre indispensables pour soutenir l'activité de recherche instrumentale en optique X et X-UV. Ce projet de pôle de METROLOGIE ne répondra pas seulement aux besoins des groupes chargés de l'équipement du synchrotron SOLEIL en optiques et détecteurs mais aussi pour préparer, tester et mettre au point les postes expérimentaux, ce qui concerne déjà une large communauté d'utilisateurs. Il sera aussi largement ouvert, dès sa mise en service, à l'ensemble de la communauté scientifique concernée par l'instrumentation X et XUV en Ile de France, en France, voire même en Europe si la demande continue de croître plus vite que l'offre dans ce domaine. Ligne de lumière Métrologie à la longueur d'onde La ligne de lumière sera équipée de plusieurs stations permettant de mesurer, dans la plus grande partie du spectre couvert par le synchrotron, les paramètres photométriques qui caractérisent les éléments optiques, tels que : la réflectivité de surfaces, l'efficacité de diffraction des réseaux, la diffusion des surfaces ou l'efficacité des détecteurs X et X-UV et la calibration absolue. Cette installation pourra servir également à développer des instruments et des diagnostics nécessaires à la caractérisation des faisceaux de rayons X (intensité, taille, degré de cohérence, polarisation etc.) Métrologie Classique La métrologie des surfaces optiques est devenue une nécessité critique pour les laboratoires et les industries qui utilisent les photons X et X-UV (synchrotrons, centres laser, etc. .). En effet, les progrès de calcul et de conception des systèmes optiques pour ces longueurs d'onde (optiques de microfocalisation, monochromateurs, diagnostics d'imagerie) font que les performances de ces instruments sont désormais limitées par les imperfections de fabrication des composants optiques. La métrologie des surfaces optiques est donc une nécessité impérieuse pour tous les acteurs du domaine, qui se doivent d'effectuer les contrôles appropriés. Cette pression s'exerce aussi sur les moyens utilisés pour effectuer ces mesures, car les incertitudes de mesure actuelles, notamment en ce qui concerne la régularité des surfaces, sont loin d'être négligeables vis à vis des tolérances demandées. Il est donc indispensable de faire évoluer les instruments de mesure et d'obtenir des gains significatifs de précision. Un travail particulier est en cours au laboratoire de Métrologie pour développer à côté des instruments commerciaux, des instruments prototypes sur des concepts originaux (mesures de profils de surface et mesures d'angle). Dans cet article, nous donnons des détails des choix techniques utilisés sur la ligne de METROLOGIE et TESTS et des performances attendues et nous décrirons le laboratoire de METROLOGIE en donnant des exemples d'optiques récemment testées.

  13. Phase transitions and reentrant phenomena in liquid crystals having both rigid and flexible intramolecular joints

    NASA Astrophysics Data System (ADS)

    Pyżuk, W.; Górecka, E.; Mieczkowski, J.; Przedmojski, J.

    1992-07-01

    Two series of liquid-crystalline compounds having three phenyl rings separated by flexible spacer —CH(CH{3})CH{2}—COO— and by rigid azo and azoxy group, were studied by DSC, optical and X-ray methods. For esters of dl-3-(4^{prime}-nitro)-phenylbutyric acid with 4^{prime}-alkoxy-phenylazo-phenol-4 having dodecyloxy or longer terminal chains, as well as for related azoxy compounds, a narrow (even below 5 K) reentrant or inverted nematic phase appearing between partly bilayer and monolayer smectics A was observed. For higher homologues of the azoxy series additional smectic phases appear, leading to the occurrence of new multicritical points, e.g. the critical end point Ad Cd N^re. On each of the lines, which separate nematic from smectic A phases, transitions are of weakly first or second-order and more than one tricritical point can occur. On the A{1} N/A{1} N^re line, a simple N A{1} tricritical point is observed at T_NI/T_AN = 0.834. The presence of further critical points depends on the components of the binary system involved. Four of the azoxy compounds studied undergo a second order phase transition between partly bilayer smectics, Ad and Cd. Such a transition is accompanied by a jumb in the specific heat, varying linearly with the length of the molecular tails. Various temperature dependences of the layer spacing in the Ad phase are observed for subsequent homologues from the azoxy series. Plusieurs cristaux liquides composés de trois groupements phényl séparés par un groupement —CH(CH{3})CH{2}—COO—, ainsi que par des groupements azo et azoxy, ont été examinés par AED, méthodes optiques et par rayons X. Pour des esters de l'acide dl-3-(4^{prime}-nitro)phénylbutyrique et de 4^{prime}-alkoxy-phénylazo-phénol-4 ayant comme terminaison une chaîne dodecyloxy ou bien plus longue, ainsi que pour des composés azoxy relatif, on observe (même au-dessous de 5 K) une étroite phase nématique réentrante ou inverse entre les phases smectiques : monocouche et partiellement bicouche. Pour des homologues plus longs dans la série des composés azoxy, on a constaté l'existence d'autres phases smectiques ce qui implique l'apparition, sur les diagrammes des phases, de nouveau points multicritiques, par exemple le point Ad Cd N^re. Sur chaque ligne séparant les phases smectiques A de la phase nématique les transitions sont faiblement du premier ordre ou du deuxième ordre ce qui mène dans certain cas à plus qu'un point tricritique. Sur la ligne A{1} N/A{1} N^re on observe à T_NI/T_AN = 0,834 un simple point tricritique N A{1} — l'apparition des autres dépend du choix des constituants du système binaire. Dans le cas de quatre composés azoxy on a constaté une transition du deuxième ordre entre les phases smectiques partiellement bicouches, Ad et Cd. La transition est accompagnée d'un brusque changement de la chaleur spécifique qui varie linéairement avec la longueur de la queue de la molécule. Pour des homologues suivants de la série des composés azoxy on observe différentes dépendances en température de la distance entre les couches de la phase Ad.

  14. Préface

    NASA Astrophysics Data System (ADS)

    Jörgen Stevefelt, Henri Bachau Et

    2003-06-01

    UVX 2002, sixième édition du “Colloque sur les Sources Cohérentes et Incohérentes UV, VUV, et X : Applications et Développements Récents" s'est tenu du 11 au 14 juin 2002 au Centre CAES du CNRS “La Vieille, Perrotine", à Saint-Pierre d'Oléron. Le colloque a réunni une centaine de chercheurs et d'industriels et a permis de faire le point sur la production, la caractérisation et l'utilisation de rayonnement dans un domaine spectral s'étendant de l'ultraviolet aux rayons X. Les participants ont pu assister a trente conférences et une table ronde autour des problèmes locaux de pollution, une cinquantaine d'affiches ont été présentées au travers de deux sessions. Une douzaine d'industriels ont exposé leurs produits durant les séances d'affiches.Conformément aux éditions précédentes, les domaines couverts par le colloque UVX 2002 sont très variés et il est impossible de les résumer en quelques lignes. Parmi les activités en développement rapide on notera les lasers femtosecondes dont les applications se multiplient dans les laboratoires (propriétés des molécules, agrégats et solides), dans l'industrie (usinage, ablation...) et en médecine. L'absence de thermalisation ou de diffusion thermique ouvre aussi des perspectives pour la réalisation de films minces par ablation laser, un domaine où les lasers excimères sont traditionnellement utilisés, avec des applications importantes dans le secteur des télécommunications. Dans le domaine de l'extrème UV, des progrès significatifs ont été réalisés par plusieurs groupes dans la gamme de longueur d'onde de 5 à 20 nm, ouvrant ainsi la voie au développement industriel de la lithographie EUV. On note les progrès dans la réalisation des sources UV et X (laser X, génération d'harmoniques, laser a électrons libres) et la nécessité de développer des optiques adaptées. Une perspective intéressante, ouverte par la génération d'harmoniques, est la production d'impulsions attosecondes qui permettra d'explorer la matière à l'echelle de temps atomique. En même temps la caractérisation de ces impulsions nécessite la conception de techniques nouvelles d'analyse du signal aux temps ultra brefs.L'intéret particulier du colloque UVX est de réunir les communautés de scientifiques qui vont des chercheurs s'intéressant aux processus fondamentaux à ceux travaillant dans les domaines les plus appliqués, voire industriels. Une caractéristique marquante de notre discipline est la rapidité avec laquelle les progrès réalisés dans les laboratoires de recherche sont diffusés vers les applications industrielles. Il est donc important de maintenir un bon équilibre entre les recherches a caractères fondamental et appliqué dans les laboratoires.Nous tenons remercier les membres du comité d'organisation, le comité scientifique et les différents partenaires, institutionnels et industriels, qui par leur soutien ont permis que le colloque UVX puisse se dérouler. Ce colloque a été parrainé par les départements des Sciences Physiques et Mathématiques (SPM) et des Sciences pour l'Ingénieur (SPI) du CNRS, la Délégation Générale de l'Armement (DGA), le CEA DRECAM, le CEA DAM, le Conseil Géneral de Charente Maritime, l'Université de Bordeaux I, la Société Française d'optique, le Groupement de Recherche “SAXO" du CNRS et la société Air Liquide.

  15. Une alternative au cobalt pour la synthese de nanotubes de carbone monoparoi par plasma inductif thermique

    NASA Astrophysics Data System (ADS)

    Carrier, Jean-Francois

    Les nanotubes de carbone de type monoparoi (C-SWNT) sont une classe recente de nanomateriaux qui ont fait leur apparition en 1991. L'interet qu'on leur accorde provient des nombreuses proprietes d'avant-plan qu'ils possedent. Leur resistance mecanique serait des plus rigide, tout comme ils peuvent conduire l'electricite et la chaleur d'une maniere inegalee. Non moins, les C-SWNT promettent de devenir une nouvelle classe de plateforme moleculaire, en servant de site d'attache pour des groupements reactifs. Les promesses de ce type particulier de nanomateriau sont nombreuses, la question aujourd'hui est de comment les realiser. La technologie de synthese par plasma inductif thermique se situe avantageusement pour la qualite de ses produits, sa productivite et les faibles couts d'operation. Par contre, des recherches recentes ont permis de mettre en lumiere des risques d'expositions reliees a l'utilisation du cobalt, comme catalyseur de synthese; son elimination ou bien son remplacement est devenu une preoccupation importante. Quatre recettes alternatives ont ete mises a l'essai afin de trouver une alternative plus securitaire a la recette de base; un melange catalytique ternaire, compose de nickel, de cobalt et d'oxyde d'yttrium. La premiere consiste essentiellement a remplacer la proportion massique de cobalt par du nickel, qui etait deja present dans la recette de base. Les trois options suivantes contiennent de nouveaux catalyseurs, en remplacement au Co, qui sont apparus dans plusieurs recherches scientifiques au courant des dernieres annees: le dioxyde de zircone (ZrO2), dioxyde de manganese (MnO2) et le molybdene (Mo). La methode utilisee consiste a vaporiser la matiere premiere, sous forme solide, dans un reacteur plasma a haute frequence (3 MHz) a paroi refroidi. Apres le passage dans le plasma, le systeme traverse une section dite de "croissance", isolee thermiquement a l'aide de graphite, afin de maintenir une certaine plage de temperature favorable a la synthese de C-SWNT. Le produit final est par la suite recolte sur des filtres metalliques poreux, une fois le systeme mis a l'arret. Dans un premier temps, une analyse thermodynamique, calculee avec le logiciel Fact-Sage, a permis de mettre en lumiere l'etat des differentes produits et reactifs, tout au long de leur passage dans le systeme. Elle a permis de reveler la similitude de composition de la phase liquide du melange catalytique ternaire de base, avec celui du melange binaire, avec nickel et oxyde d'yttrium. Par la suite, une analyse du bilan d'energie, a l'aide d'un systeme d'acquisition de donnees, a permis de determiner que les conditions operatoires des cinq echantillons mis a l'essai etaient similaires. Au total, le produit final a ete caracterise a l'aide de six methodes de caracterisations differentes : l'analyse thermogravimetrique, la diffraction de rayons X, la microscopie electronique a balayage a haute resolution (HRSEM), la microscopie electronique a transmission (MET), la spectroscopie RAMAN, ainsi que la mesure de la surface specifique (BET). Les resultats de ces analyses ont permis de constater, de facon coherente, que le melange a base de molybdene etait celui qui produisait la moins bonne qualite de produit. Ensuite, en ordre croissant, s'en suivait du melange a base de MnO2 et de ZrO2. Le melange de reference, a base de cobalt, est au deuxieme rang en matiere de qualite. La palme revient au melange binaire, dont la proportion est double en nickel. Les resultats de ce travail de recherche permettent d'affirmer qu'il existe une alternative performante au cobalt pour effectuer la synthese de nanotubes de carbone monoparoi, par plasma inductif thermique. Cette alternative est l'utilisation d'un melange catalytique binaire a base de nickel et d'oxyde d'yttrium. Il est suggere que les performances plus faibles des recettes alternatives, moins performantes, pourraient etre expliquees par le profil thermique fixe du reacteur. Ceci pourrait favoriser certains melanges, au detriment des autres, qui possedent des proprietes thermodynamiques differentes. Le montage, l'equipement, ainsi que les parametres d'operations, pourraient etre modifies en fonction de ces catalyseurs afin d'optimiser la synthese. Mots cles : nanotubes de carbone mono paroi, plasma inductif thermique, cobalt, nickel, dioxyde de zirconium, dioxyde de manganese, molybdene, trioxyde d'yttrium et noir de carbone

  16. Pulsed laser deposition of {CeO_2} and {Ce_{1-x}M_xO_2} (M = La, Zr): Application to insulating barrier in cuprate heterostructures

    NASA Astrophysics Data System (ADS)

    Berger, S.; Contour, J.-P.; Drouet, M.; Durand, O.; Khodan, A.; Michel, D.; Régi, F.-X.

    1998-03-01

    SrTiO_3 had been often tentatively used as an insulating barrier for HT superconductor/insulator heterostructures. Unfortunately, the deposition of SrTiO_3 on the YBa_2Cu_3O_7 inverse interface results in a poor epitaxial regrowth producing a high roughness dislocated titanate layer. Taking into account the good matching with YBa_2Cu_3O_7 and LaAlO_3, CeO_2 and Ce_{1-x}M_xO_2 (M = La, Zr), epitaxial layers were grown by pulsed laser deposition on LaAlO_3 substrates and introduced into YBa_2Cu_3O_7 based heterostructures as insulating barrier. After adjusting the growth parameters from RHEED oscillations, epitaxial growth is achieved, the oxide crystal axes being rotated by 45^circ from those of the substrate. The surface roughness of 250 nm thick films is very low with a rms value lower than 0.5 nm over 1;μ m^2. The YBa_2Cu_3O_7 layers of a YBa_2Cu_3O_7/CeO_2 /YBa_2Cu_3O_7 heterostructures grown using these optimized parameters show an independent resistive transition, when the thickness is larger than 25 nm, respectively at T_c_1 = 89.6;K and T_c_2 = 91.4;{K}. SrTiO3 est souvent utilisé comme barrière isolante dans des hétérostructures SIS de cuprates supraconducteurs, cependant les défauts générés lors de la croissance de ce titanate sur l'interface inverse de YBa2Cu3O7 conduisent à un matériau dont la qualité cristalline et les propriétés physiques sont médiocres. L'oxyde de cérium CeO2 est également une barrière isolante potentielle intéressante pour ces structures SIS basées sur YBa2Cu3O7 car cet oxyde cubique (a = 0,5411 nm, asqrt{2}/2 = 0,3825 nm) qui est peu désaccordé par rapport au plan ab du cuprate (Δ a/a = - 0,18 %, Δ b/a = 1,6 %) présente de plus un coefficient de dilatation thermique (10,6 × 10^{-6 circ}C^{-1}) très voisin de celui de YBa2Cu3O7 (13 × 10^{-6 circ}C^{-1}). Nous avons donc étudié l'épitaxie de CeO2 et des oxydes de type Ce{1-x}MxO2 (M = La, Zr) en ablation laser pulsée afin de définir des conditions de croissance optimisées pour la réalisation de barrières isolantes ultra-minces à faible rugosité d'interface. L'interface de croissance a été caractérisée par analyse en diffraction d'électrons rapides en incidence rasante (RHEED) en temps réel et par analyse ex-situ en microscopie par force atomique (AFM) et diffraction de rayons X (DRX). Lorsque les paramètres de la croissance (T, p_O_2, fréquence du laser, distance cible-substrat...) sont optimisés par observation des oscillations d'intensité de RHEED, les films sont épitaxiés à 45^{circ} des axes du substrat. La rugosité rms d'un film de 250 nm d'épaisseur déterminée par AFM sur 1 μ m^2 est alors inférieure à 0,5 nm, c'est-à-dire de l'ordre de la hauteur d'une maille élémentaire. Ces conditions optimisées ont été utilisées pour la réalisation d'hétérostructures YBa2Cu3O7/CeO2/YBa2Cu3O7, lorsque l'épaisseur est supérieure à 25 nm, les couches élémentaires de YBa2Cu3O7 présentent des transitions résistive indépendantes respectivement à T_c_1 = 89,6 K et T_c_2 = 91,4 K.

  17. Review of the critical current densities and magnetic irreversibilities in high T_c superconductors

    NASA Astrophysics Data System (ADS)

    Senoussi, S.

    1992-07-01

    This review article is concerned with critical current density (J) and magnetic irreversibilities in high-T_c superconductors (HTSC). The apparent J derived from different experimental techniques (transport, hysteresis cycle, ac-susceptibility) are compared. The influence of time (relaxation effects) as well as the macroscopic size of the sample on the criteria defining J are discussed. The dependences of the critical current on grain boundaries (“weaks-links”), texturing and other physical and chemical defects are examined in detail. The role of self fields is clarified. The critical current is strongly influenced by the anisotropy of the layered structure practically whatever the experimental conditions. Intrinsic pinning is lowered by defects. Demagnetizing effects and surface pinnings are reviewed. The usual critical state and flux creep models are recalled emphasizing the physical aspects most specific to HTSC. A theoretical model which takes into account the equilibrium magnetization and sample granularity is developed. It reproduces most of the characteristic features of both the hysteresis cycle and ac-susceptibility. A number of new formulae are introduced. They generalize the Bean model and show how to correct for the dimensions of the grains (granular materials), the macroscopic radius of the sample, anisotropy and demagnetization effects in certain situations. Several limits beyond which the usual critical state breaks down are discussed: (1) the quasi elastic limit where the variable field is too weak to depin the vortices, (2) H≈ H_C1 so that the interaction between vortex lines is exponentially weak and (3) T and H close to the “irreversibility line” where the influence of viscous forces are strong. (4) Hgg H_C1 so that J is governed by collective pinning. Ce papier de revue est consacré aux courant critiques (J) et aux irréversibilités magnétiques dans les nouveaux matériaux supraconducteurs (HTSC). Nous y comparons les densités des courants critiques effectives déduites à partir des techniques expérimentales les plus courantes (transport, cycle d'hystérésis, susceptibilité alternative, ...). L'influence de l'échelle du temps de la mesure et de la taille effective de l'échantillon sur les divers critères définissant J est examinée en détail. La dépendance de ce courant en fonction des joints de grains (“liens faibles”), du degré de texture et des autres défauts physiques et chimiques est discutée. Le rôle du champ propre est clarifié. Le courant critique est très dépendant de l'anisotropie de l'échnatillon dans pratiquement toutes les conditions expérimentales. L'ancrage intrinsèque est détérioré par les défauts. Le rôle des effets démagnétisants et de la surface de l'échantillon sur les résultats expérimentaux est passé en revue. Les modèles de l'état critique et de “flus creep” sont rappelés en insistant sur les aspects les plus spécifiques des HTSC. Un modèle théorique est proposé. Il tient compte de l'aimantation réversible, des aspects granulaires et reproduit à la fois les propriétés les plus typiques des cycles d'hystérésis et de la suscceptibilité alternative. Plusieurs formules nouvelles généralisant le modèle de Bean en sont déduites. Elles montrent comment tenir compte des dimensions des grains (matériaux granulaires), du rayon macroscopique, de l'anisotropie et des effets démagnétisants, dans certaines conditions. Plusieurs limites au-delà desquelles les concepts classiques de l'état critique cessent d'être valides sont également examinés : (1) la limite élastique où le champ de mesure est trop faible pour dépiéger les vortex, (2) H≈ H_C1 de sorte que les interactions entre vortex sont exponentiellement faibles et (3) et T voisins de la ligne d'irréversibilité où les forces de viscosité jouent un rôle prépondérant. (4) Hgg H_C1 de sorte que J est imposé par l'ancrage collectif.

  18. Analyse de la formation des phases du systeme cuivre-germanium par diffraction des rayons X sur des echantillons d'epaisseur nanoscopique

    NASA Astrophysics Data System (ADS)

    Aubin, Alexandre

    With the miniaturization of electronic devices, driven by cost reduction and performance increase, new materials have to be introduced in their fabrication process to solve many emerging problems. These challenges are brought forth by the ITRS (International Technology Roadmap for Semiconductors), a comity in charge of listing the technological needs for the upcoming generations of integrated circuits. Many fields of interest require new technological developments, from global to local interconnections, the transistor gate, the gate insulator thickness, etc. One of the major challenges mentioned in the ITRS roadmap is the need for a new interconnection material. Indeed, the need for a diffusion barrier for the copper lines in local and global interconnections of integrated circuits, the main technology in today's devices, is becoming more hindering with the decrease of the metallization lines. cross-section. In the 90's, a binary compound of copper and germanium, known as the epsilon1-Cu3Ge phase, was investigated as a replacement for aluminum because of its low resistivity, that can reach as low as 5.5muO·cm [1], its stability in contact with both silicon and silicon oxide [2] as well as its thermal stability during anneals [3]. However, copper proved to be a better choice at the time because of its low bulk resistivity of 1.68muO·cm at room temperature[4]. The objective of this master thesis is to re-examine the copper-germanium system, and more specifically the epsilon1-Cu3Ge, for future applications in the microelectronics industry. Different X ray diffraction techniques were used to obtain more information on the system, including in situ X ray diffraction during 3°C/s anneals in an inert helium atmosphere with simultaneous resistance measurement, theta-2theta scans to detect diffraction peaks of the present phases after sample quenching as well as partial acquisition of the reciprocal space of quenched samples which allowed to obtain pole figures for d-spacings of interest. Results obtained on germanium and copper bilayers of total thicknesses between 20nm and 89nm deposited on an inert silicon nitride layer using magnetron sputtering in an MRC-673 show that with an atomic copper concentration between 72 and 87%, the epsilon1-Cu3Ge phase starts to form between 180°C and 210°C during a 3°C/s ramp anneal. At 72% at. copper (50nm thickness) and 75% at. copper (20nm thickness), the epsilon1-Cu3Ge phase is stable above 500°C. However, the measured resistance of the 50nm sample is low between 220°C and 500°C while measured resistance for the 20nm sample it decreases by 45% between 205 and 540°C. At a temperature of 540°C, measured resistance is 10% smaller than on the initial bilayer at room temperature. This value of measured resistance is the same at the end of the measurement during the cooling of the sample at 230°C., which implies that the low resistance is kept after the phase formation. Smaller technology nodes may then require higher formation temperatures to completely form the epsilon1-Cu3Ge phase. Further challenges thus exist to make epsilon1-Cu3Ge interconnections in modern microelectronics devices. Tests with deposition techniques like co-deposition and multilayer stacks of germanium and copper must be made to determine if they can help resolve this problem. Another field of interest for further tests are isothermal anneals, which would allow the formation of the epsilon1-Cu3Ge phase during longer anneals at lower temperatures. This thesis also allowed the acquisition of the phase formation sequence of different samples thicknesses between 20 and 89nm and copper concentrations between 72 and 87% atomic copper during 3°C/s anneals up to 850°C using in situ X ray diffraction. Brand new information was acquired on the metastable phases of the copper-germanium system. Observed diffraction peaks allowed to confirm the crystalline structures observed by Schubert and Brandauer in the 50's [5] as well as estimate the cell parameter of the body centered cubic epsilon2- Cu3Ge, which is approximately 5.03 A. Simultaneous formation of zeta-Cu5Ge and epsilon1-Cu 3Ge was also observed in a 82 % at. copper sample, which had not previously been reported in the literature.

  19. Etude des phenomenes chimiques au contact entre le bloc cathodique et la barre collectrice d'une cellule d'electrolyse d'aluminium

    NASA Astrophysics Data System (ADS)

    Lebeuf, Martin

    La production d'aluminium est une industrie importante au Québec. Les propriétés de ce métal le vouent à de multiples usages présents et futurs dans le cadre d'une économie moderne durable. Toutefois, le procédé Hall-Héroult est très énergivore et des progrès demeurent donc nécessaires pour en diminuer les coûts financiers et environnementaux. Parmi les améliorations envisageables de la cellule d'électrolyse se trouve le contact entre la cathode et la barre collectrice, qui doit offrir une faible résistivité au passage du courant électrique. En cours d'opération de la cellule, ce contact a tendance à se dégrader, générant des pertes énergétiques significatives. Les causes de cette dégradation, pouvant provenir de phénomènes chimiques, thermiques, mécaniques et/ou électriques, demeurent mal comprises. Le but du présent projet était donc d'étudier les phénomènes chimiques se produisant au contact bloc-barre de la cellule d'électrolyse Hall-Héroult. En premier lieu, un aspect crucial à considérer est la pénétration du bain électrolytique dans la cathode, car des composés de bain atteignent éventuellement la barre collectrice et peuvent y réagir. A cet effet, une méthode novatrice a été développée afin d'étudier les cathodes et la pénétration du bain dans celles-ci à l'aide de la microtomographie à rayons X. Cette méthode rapide et efficace s'est avérée fort utile dans le projet et a un potentiel important pour l'étude future des cathodes et des phénomènes qui s'y produisent. Ensuite, une cellule d'électrolyse rectangulaire à petite échelle a été développée. Plusieurs phénomènes observés 'en industrie sur des autopsies de cellules post-opération et rapportés dans la littérature ont été reproduis avec succès à l'aide de cette cellule expérimentale. Puis, des tests sans électrolyse, ciblant l'effet du bain électrolytique sur l'acier, ont aussi été conçus et complétés afin de ségréger l'influence des différents paramètres en jeu. L'analyse des résultats de l'ensemble de ces tests a permis de constater différents phénomènes au contact bloc-barre, dont la présence systématique de NaF et, surtout, de β-Al 2O3. Outre la carburation inévitable de la barre collectrice, la formation d'une couche Fe-Al a aussi été observée, favorisée par une pénétration rapide du bain électrolytique dans la cathode ainsi que par une composition de bain acide en surface de la barre. Cette couche comportait par ailleurs des cristaux de β-Al 2O3 pouvant nuire à sa conductivité électrique. Ensuite, à des ratios de bain entre 2.5 et 4.9, une mince couche contenant les éléments Al et N peut se former en surface de la barre. Pour un bain très basique (> 6.0), c'est plutôt une couche Na 2O qui a été observée. En conditions d'électrolyse mais sans une pénétration rapide du bain dans la cathode, du Na a pu carrément pénétrer dans la barre collectrice, préférentiellement avec le carbone. De plus, de la corrosion ainsi que des couches de fer et d'oxyde de fer peuvent se former sur la barre et potentiellement dégrader la qualité du contact électrique. Pour la suite des travaux, des mesures de résistivité ainsi que l'analyse des échantillons industriels permettraient d'évaluer l'impact de ces phénomènes sur la qualité du contact. Mots-clés : Électrolyse, aluminium, Hall-Héroult, interface barre-cathode, bain électrolytique.

  20. Le Phénomène Wolf-Rayet au Sein des Etoiles chaudes de Populations I et II: Histoire des Vents stellaires et Impact sur la Structure nébulaire circumstellaire

    NASA Astrophysics Data System (ADS)

    Grosdidier, Yves

    2000-12-01

    Les spectres des étoiles Wolf-Rayet pop. I (WR) présentent de larges raies en émission dues à des vents stellaires chauds en expansion rapide (vitesse terminale de l'ordre de 1000 km/s). Le modèle standard des étoiles WR reproduit qualitativement le profil général et l'intensité des raies observées. Mais la spectroscopie intensive à moyenne résolution de ces étoiles révèle l'existence de variations stochastiques dans les raies (sous-pics mobiles en accélération échelles de temps: environ 10-100 min.). Ces variations ne sont pas comprises dans le cadre du modèle standard et suggèrent une fragmentation intrinsèque des vents. Cette thèse de doctorat présente une étude de la variabilité des raies spectrales en émission des étoiles WR pop. II; la question de l'impact d'un vent WR fragmenté sur le milieu circumstellaire est aussi étudiée: 1) à partir du suivi spectroscopique intensif des raies CIIIl5696 et CIVl5801/12, nous analysons quantitativement (via le calcul des Spectres de Variance Temporelle) les vents issus de 5 étoiles centrales de nébuleuses planétaires (NP) galactiques présentant le phénomène WR; 2) nous étudions l'impact de la fragmentation des vents issus de deux étoiles WR pop. I sur le milieu circumstellaire via: i) l'imagerie IR (NICMOS2/HST) de WR 137, et ii) l'imagerie H-alpha (WFPC2/HST) et l'interférométrie Fabry-Perot H-alpha (SIS-CFHT) de la nébuleuse M 1-67 (étoile centrale: WR 124). Les principaux résultats sont les suivants: VENTS WR POP. II: (1) Nous démontrons la variabilité spectroscopique intrinsèque des vents issus des noyaux de NP HD 826 ([WC 8]), BD +30 3639 ([WC 9]) et LSS 3169 ([WC 9]), observés durant respectivement 22, 15 et 1 nuits, et rapportons des indications de variabilité pour les noyaux [WC 9] HD 167362 et He 2-142. Les variabilités de HD 826 et BD +30 3639 apparaissent parfois plus soutenues (``bursts'' qui se maintiennent durant plusieurs nuits); (2) La cinématique des sous-pics de BD +30 3639 suggère une anisotropie transitoire de la distribution des fragments dans le vent; (3) Le phénomène WR apparaît purement atmosphérique: la cinématique des sous-pics, les amplitudes et les échelles de temps caractéristiques des variations, ainsi que les accélérations observées sont similaires pour les deux populations. Mais, pour HD 826, une accélération maximale d'environ 70 m/s2 est détectée, valeur significativement plus importante que celles rapportées pour les autres étoiles WR pop. I & II (environ 15 m/s2). La petitesse du rayon de HD 826 en serait la cause; (4) Comme pour les WR pop. I, de grands paramètres (β supérieur ou égal à 3-10) sont requis pour ajuster les accélérations observées avec une loi de vitesse de type beta. La loi beta sous-estime systématiquement les gradients de vitesse au sein de la région de formation de la raie CIIIl5696; (5) Les vents WR pop. II étant fragmentés, l'estimation des taux de perte de masse actuels à partir de méthodes supposant les atmosphères homogènes conduit à une surestimation i) des taux de perte de masse eux-mêmes, et ii) des masses initiales des étoiles avant qu'elles n'entrent dans la phase WR. IMPACT DES VENTS: (1) Au périastre, de la poussière est détectée dans l'environnement de la binaire WC+OB WR 137. La formation de poussières est soit facilitée, soit provoquée par la collision des deux vents chauds; le rôle capital de la fragmentation des vents (fournissant une compression localisée supplémentaire du plasma) est suggéré (2) La nébuleuse M 1-67 affiche une interaction avec le milieu interstellaire (MIS) non-négligeable (``bow-shock''). Les champs de densité et de vitesse sont très perturbés. Ces perturbations sont reliées, d'une part, à l'histoire des vents issus de WR 124 durant sa propre évolution, d'autre part, à l'interaction avec le MIS. Les fonctions de structure des champs de densitéet de vitesse de M 1-67 ne révèlent aucun indice en faveur d'une turbulence au sein de la nébuleuse (3) Des simulations hydrodynamiques 2D réalisées avec le code ZEUS-3D montrent qu'un fragment dense formé près du coeur hydrostatique stellaire ne peut probablement pas, sans adjoindre les effets de bouclier et de confinement radiatifs, atteindre des distances nébulaires.

  1. In situ and laboratory investigations of fluid flow through an argillaceous formation at different scales of space and time, Tournemire tunnel, southern France

    NASA Astrophysics Data System (ADS)

    Boisson, Jean-Yves; Bertrand, Lucien; Heitz, Jean-François; Golvan, Yann Moreau-Le

    2001-01-01

    In the context of a research and development program on waste disposal, an experimental site (Tournemire tunnel, Aveyron, France) was selected by the French Institute for Nuclear Protection and Safety (IPSN) in order to undertake studies on potential fluid flow at different scales of space and time within a 250-m-thick argillaceous formation. The argillite has a low natural water content ( 3-5%) and very low radii access porosity. Diffusion (tritiated water) coefficients (1×10-12 to 2×10-11 m2/s) and hydraulic conductivities derived from different types of laboratory tests (10-14 to 10-13 m/s) are characteristics of a very low-permeable rock. In situ hydraulic tests (including long-term hydraulic-head measurements) were used to obtain values for hydraulic head and hydraulic conductivity at a scale of 1-10 m (10-13 to 10-11 m/s). Despite uncertainties on these data (due to a scale factor, presence of fissures, and possible artefacts due to hydro-chemo-mechanical coupling), it is expected that fluid flow is essentially governed by diffusion processes. Identification of possible natural flows at larger scales of time and space was investigated using natural isotopic tracers from interstitial fluids. Modelling, based on the deuterium profile along the clay formation and assuming pure diffusion processes, provides estimations of possible flow times. However, lack of knowledge concerning the past geological evolution of the site and the possible role of a fracture network do not permit reduction of uncertainties on these estimations at this stage. Résumé. Dans le cadre de son programme de recherche et développement sur les stockages de déchets, un site expérimental (tunnel de Tournemire, Aveyron, France) a été sélectionné par l'Institut de Protection et Sûreté Nucléaire (IPSN) pour conduire des études sur les possibilités de transferts de fluides à différentes échelles de temps et d'espace au sein d'une formation argileuse de 250 m d'épaisseur. L'argilite est caractérisée par de faibles teneurs en eau ( 3-5%) et de très petits rayons d'accès de pores. Les coefficients de diffusion à l'eau tritiée (1×10-12 à 2×10-11 m2/s) et les conductivités hydrauliques déduites de différents types d'essais au laboratoire (10-13 à 10-14 m/s) sont caractéristiques d'une roche très imperméable. Des tests hydrauliques in situ (y compris une mesure de charge à long terme) ont fourni des valeurs approchées des charges et un ordre de grandeur des perméabilités à l'échelle de 1-10 m (10-11 à 10-13 m/s). En dépit des incertitudes sur ces données (facteur d'échelle, présence de fissures, et artéfacts possibles dus aux couplages hydro-chimique et mécanique) on suppose que les transferts sont essentiellement gouvernés par des processus diffusifs. La reconnaissance de transferts naturels possible à une plus grande échelle de temps et d'espace a été étudiée à partir des traceurs isotopiques naturels des fluides interstitiels. Une modélisation, basée sur un profil en deutérium le long de la colonne argileuse et postulant un processus diffusif a permis de proposer une estimation de temps de transfert possible, mais le manque de connaissances précises au stade actuel de l'étude concernant l'évolution géologique passée du site et le rôle possible de la fracturation ne permet pas de réduire les incertitudes constatées sur ces estimations. Resumen. Dentro del contexto de un programa de investigación y desarrollo para la eliminación de residuos, el Instituto Francés de Protección Nuclear y Seguridad seleccionó un emplazamiento experimental en el túnel de Tournemire (Aveyron, Francia) para llevar a cabo estudios sobre el flujo potencial de fluídos a diferentes escalas temporales y espaciales, en una formación arcillosa de 250 m de espesor. La argilita tiene un contenido natural bajo de agua ( 3-5%) y una porosidad accesible muy pequeña. Los coeficientes de difusión de agua con tritio (entre 10-12 y 2×10-11 m2/s) y las conductividades hidráulicas calculadas a partir de diferentes ensayos de laboratorio (entre 10-13 y 10-14 m/s) son característicos de rocas de muy baja permeabilidad. Se hicieron ensayos hidráulicos in-situ (incluyendo medidas de nivel piezométrico de larga duración) para obtener valores del nivel piezométrico y de la conductividad hidráulica a una escala de 1-10 m (con valores entre 10-11 y 10-13 m/s). A pesar de las incertidumbres sobre estos datos (debido a factores de escala, a la presencia de fisuras y a posibles artificios ocasionados por el acoplamiento hidro-quimiomecánico), se espera que el flujo de fluídos esté esencialmente controlado por procesos de difusión. La identificación de posibles flujos naturales a escalas temporales y espaciales mayores fue investigada mediante trazadores isotópicos naturales del fluído intersticial. La modelación, basada en el perfil de deuterio a lo largo de la formación de arcilla y en la hipótesis de procesos puramente difusivos, proporciona estimaciones de posibles tiempos de tránsito. Sin embargo, la falta de conocimiento sobre la evolución geológica del lugar y sobre el rol potencial de una red de fracturas no permite reducir las incertidumbres asociadas, en el momento actual, a dichas estimaciones.

  2. Préface

    NASA Astrophysics Data System (ADS)

    Moncorgé, R.

    2006-12-01

    Cette nouvelle édition du Colloque UVX avait pour objectifs de : - réunir les chercheurs et les industriels intéressés par les applications et les développements les plus récents obtenus sur les sources UV, VUV et X, cohérentes ou incohérentes, et les optiques et matériaux associés ; - dresser un bilan des sources de photons à haute énergie et de leurs applications courantes et futures ; - susciter de nouvelles collaborations ; - ouvrir de nouveaux champs disciplinaires. Elle a été organisée par le laboratoire CIRIL au VVF de Colleville-sur-Mer, dans le département du Calvados, du 6 au 9 juin 2006, la journée du 5 juin ayant été consacrée à une réunion de travail du GDR CNRS SAXO, ce GDR regroupant une majorité de scientifiques concernés par le Colloque UVX. La manifestation a réuni ainsi une centaine de participants dont une dizaine d'exposants industriels. Parmi ces participants, trente étaient invités à donner une conférence orale. Une sélection a été faite également parmi les meilleures communications soumises par affiches pour qu'elles soient présentées oralement. Une trentaine de ces communications ont été préparées sous la forme d'articles de 6 à 12 pages et font l'objet de cet ouvrage. De nombreux travaux récents ont été exposés tant au niveau des sources que des techniques de caractérisation et des applications, ceci dans des domaines très divers allant de la physique des lasers et de la mise en forme spatiale et temporelle des faisceaux au domaine de l'imagerie médicale et biologiques en passant par les techniques de fabrication des cristaux, fibres et films minces organiques et inorganiques. Plusieurs résultats marquants en sont ressortis. Dans le domaine des sources, la mise en forme spatiale du faisceau laser utilisé pour la production d'harmoniques d'ordre élevé dans les gaz, ceci à l'aide de lames de phase peu onéreuses et simples d'utilisation, semble être une bonne solution pour accroître les efficacités de conversion et pour produire des impulsions UVX de quelques dizaines de microjoules. Parallèlement, des progrès notables ont été effectués dans la génération d'impulsions sub-100 as isolées accordables et de large bande spectrale en utilisant des impulsions de pompe ultracourtes bien contrôlée en phase. Il apparaît que la gamme spectrale accessible peut être encore largement étendue en jouant sur la longueur d'onde excitatrice et sur le milieu générateur pour pouvoir atteindre des impulsions de moins de 10 as. Des premiers résultats ont été aussi exposés concernant l'obtention d'un laser X à 18,9 nm pompé en incidence rasante (technique GRIP) à partir d'une cible de molybdène nickelloide et d'un laser Ti:Sa produisant des impulsions de plus de 2 microjoules. L'intérêt des milieux gazeux à excimères a été également de nouveau démontré pour l'amplification d'impulsions ultracourtes intenses TW dans le proche UV avec un contraste élevé (>1011). Bien qu'encore marginale, il faut enfin signaler l'arrivée des fibres optiques microstructurées avec la génération de supercontinuum de longueurs d'onde (spectre blanc) jusque dans le proche UV. Du côté des processus fondamentaux et des applications, sont particulièrement ressortis la caractérisation de plasmas denses utilisant des harmoniques élevées à l'aide d'une expérience interférométrique originale, la caractérisation de plasmas de taille nanométrique émetteurs de rayonnement X produits par interaction d'impulsions laser ultracourtes avec des agrégats de gaz rares ainsi que le dépôt de couches minces de biomolécules à l'aide de la technique MAPLE, technique susceptible d'améliorer la conservation des molécules, en particulier des protéines. Enfin, dans le domaine de la métrologie et de l'imagerie, l'importance des lames de phase dans la mise en forme spatiale des faisceaux, en particulier pour le projet Mega-Joule, a été de nouveau souligné, des progrès significatifs (réflectivité, bande passante, stabilité temporelle et thermique) ont été obtenus dans le domaine des revêtements interférentiels multicouches pour laser EUV autour de 40 nm, et des améliorations significatives, en particulier au niveau des détecteurs, ont été signalées dans le domaine de l'imagerie X du petit animal, la conception de sources dédiées à microfoyers délivrant des rayons X de basses énergies très rapides pour éviter le flou inhérent aux mouvements de l'animal restant encore nécessaire. Le Colloque a permis des échanges très fructueux entre laséristes et utilisateurs et entre scientifiques et industriels commercialisant sources, systèmes et détecteurs. Il a permis également de donner la parole à des intervenants très jeunes et souvent très brillants (doctorants et jeunes chercheurs) qui seront sans aucun doute les futurs responsables de nos laboratoires, centres de recherche et entreprises. Les progrès constatés résultant de travaux portant souvent sur les deux années écoulées (puisque c'est la fréquence choisie pour ce Colloque) et les résultats obtenus comme les perspectives annoncées montrant de nouveau toute la pertinence de cette manifestation, celle-ci sera reconduite en 2008.

  3. Préface

    NASA Astrophysics Data System (ADS)

    Paulus, Werner; Meinnel, Jean

    2003-02-01

    En 1994, l'attribution du prix Nobel à Cliff Shull et Bert Brockhouse pour leurs travaux de pionniers pendant les années 50, concernant tant la diffusion élastique des neutrons que la diffusion inélastique, a été la reconnaissance éclatante de l'importance de la diffusion neutronique pour toute la communauté scientifique.Le grand intérêt du neutron pour la recherche s'appuie principalement sur ses propriétés physiques particulières :- les neutrons utilisés pour la caractérisation de la matière (et fournis en relativement grandes quantités par les réacteurs ou les sources à spallation) disposent de longueurs d'onde et d'énergies correspondant directement aux distances interatomiques et aux énergies d'agitation de la matière. Ainsi, par diffusion neutronique, on peut étudier en même temps la structure et le comportement dynamique de la matière ;- le fait que le neutron soit doué d'un moment magnétique lui permet d'interagir avec tout atome porteur d'un moment magnétique. Ceci permet de caractériser intimement le comportement magnétique de la matière à l'échelle microscopique ;- la possibilité de pouvoir varier facilement le contraste d'un même élément en utilisant ses différents isotopes fait du neutron un outil irremplaçable en chimie et physique du solide ainsi qu'en biologie et matière molle ;- enfin, n'ayant pas de charge électrique, les neutrons peuvent pénétrer la matière sans être absorbés significativement, ce qui rend possible une caractérisation non destructive des contraintes et textures sur de grosses pièces des matériaux.Toutes les qualités des neutrons mentionnées ci-dessus permettent de comprendre l'importance de la diffusion neutronique pour des domaines très nombreux et très différents à la fois en recherche fondamentale mais aussi pour des applications industrielles. L'utilisation de l'outil-neutron demande toutefois non seulement une bonne connaissance des différents mécanismes d'interaction entre le neutron et la matière, mais également une haute spécificité dans la conception et l'utilisation des diffractomètres et spectromètres neutroniques. Pour ces raisons, l'accès aux neutrons est souvent limité, sinon réservé à des spécialistes, ce qui freine tout naturellement l'utilisation par des chercheurs non familiarisés à ce domaine.Pour combattre ce déficit d'information et cet état de fait, en accord avec de nombreux collègues Rennais, nous avons proposé à la Société Française de Neutronique d'organiser une École d'été qui s'adresse plus spécialement à de non-spécialistes de la diffusion neutronique. Le public visé concernait donc à la fois les chercheurs confirmés mais peu familiarisés avec le domaine neutronique, mais aussi les jeunes chercheurs dès le niveau doctorant. En effet pour ces derniers, l'utilisation des “grands instruments" s'avère nécessaire pour qu'ils soient à la hauteur de leur sujet de thèse. Pour cette raison, il était évident d'intégrer cette École d'été dans le programme de l'École Doctorale “Sciences des Matériaux" de l'Université de Rennes 1 qui rassemble chimistes, physiciens et géologues. Dans le même contexte, notre intérêt était de proposer un large spectre de cours couvrant la diversité des applications de la diffusion neutronique dans les différents domaines de recherche en chimie et physique des matériaux, en sciences de la terre ainsi qu'en sciences pour l'ingénieur. Un deuxième but était de montrer de plus la complémentarité des neutrons et des rayons X et plus spécifiquement des X produits par rayonnement synchrotron.Dans l'avenir, nous sommes persuadés que la diffusion neutronique va jouer un rôle clé pour le développement de nouveaux matériaux et de leur caractérisation. Dans cette optique, des efforts considérables ont été déjà engagés aux États-Unis ainsi qu'au Japon où deux nouvelles sources de neutrons sont en cours de construction. Du point de vue européen, si les sources de l'ILL et d'ISIS peuvent encore être considérées comme des leaders au point de vue mondial, il est évidemment souhaitable que la nouvelle source neutronique à spallation (European Spallation Source : ESS) soit rapidement réalisée. Aujourd'hui ce projet est bien avancé, cette source devrait dépasser le flux des sources actuelles par près de deux ordres de grandeur et ainsi de maintenir au meilleur niveau les compétences Européennes. Il est évident qu'une utilisation efficace et intelligente des sources existantes, mais aussi de celles de la nouvelle génération, implique une certaine infrastructure nationale tant au niveau de la conception, de la réalisation que du fonctionnement des différents spectromètres. Ceci implique un très fort engagement des universités dans les différents projets de recherche. Le devoir des universités qui en résulte est donc d'intégrer l'utilisation des “grands instruments" dans leur programme d'enseignement. Dans ce sens, nous souhaitons que ce cours, entièrement rédigé en français, contribue à la fois à aider les chercheurs “non spécialistes” à accéder plus facilement au domaine neutronique, mais aussi à servir de base aux enseignants pour l'organisation et la préparation de leurs cours.Nous tenons à remercier tous les collègues qui ont accepté de rédiger de façon détaillée les cours qu'ils avaient présentés oralement dans la grande salle du VVF de Trégastel, ainsi que toutes les personnes qui ont contribué à la réussite du séjour ou à la réalisation de ce fascicule. Nous gardons un excellent souvenir de l'atmosphère de l'École qui a eu lieu à Trégastel, en plein centre de la côte de granite rose en Bretagne, en mai 2001 et était jumelée avec les Journées de la diffusion neutronique, elles aussi organisées sous l'égide de la SFN.Nous souhaitons que la lecture de cet ouvrage soit utile à un maximum de chercheurs.

  4. Nucléation, ascension et éclatement d'une bulle de champagne

    NASA Astrophysics Data System (ADS)

    Liger-Belair, G.

    2006-03-01

    People have long been fascinated by bubbles and foams dynamics, and since the pioneering work of Leonardo da Vinci in the early 16th century, this subject has generated a huge bibliography. However, only quite recently, much interest was devoted to bubbles in Champagne wines and carbonated beverages. Since the time of the benedictine monk dom Pierre Perignon (1638-1715), champagne is the wine of celebration. This fame is largely linked to the elegance of its effervescence and foaming properties. In this book, the latest results about the chemical physics behind the bubbling properties of Champagne and sparkling wines are collected and fully illustrated. The first chapter is devoted to the history of champagne and to a presentation of the tools of the physical chemistry of interfaces needed for a whole comprehension of the book. Then, the three main steps of a fleeting champagne bubble's life are presented in chronological order, that is, the bubble nucleation on the glass wall (Chap.2), the bubble ascent and growth through the liquid matrix (Chap.3), and the bursting of bubbles at the liquid surface (Chap.4), which constitutes the most intriguing, functional, and visually appealing step. L'objectif général de ce travail consacré à l'étude des processus physicochimiques liés à l'effervescence des vins de Champagne était de décortiquer les différentes étapes de la vie d'une bulle de champagne en conditions réelles de consommation, dans une flûte. Nous résumons ci-après les principaux résultats obtenus pour chacune des étapes de la vie de la bulle, depuis sa naissance sur les parois d'une flûte, jusqu'à son éclatement en surface. Nucléation À l'aide d'une caméra rapide munie d'un objectif de microscope, nous avons pu mettre à mal une idée largement répandue. Ce ne sont pas les anfractuosités de la surface du verre ou de la flûte qui sont responsable de la nucléation hétérogène des bulles, mais des particules adsorbées sur les parois du verre ou de la flûte. Dans la majorité des cas, il s'agit de fibres de cellulose creuses dont les propriétés géométriques permettent le piégeage d'une poche d'air en leur sein au moment du versement. Un modèle de piégeage a été construit et met en avant le rôle fondamental joué par la vitesse du versement. Plus cette vitesse augmente, plus on augmente la probabilité de piéger des poches d'air au sein de ces fibres, provoquant ainsi une effervescence plus importante. La dynamique de production des bulles a également été filmée in situ à l'aide de la caméra, puis modélisée en utilisant les équations de la diffusion adaptées à la géométrie de notre fibre supposée approximativement cylindrique. Nous avons montré que le temps caractéristique de production d'une bulle par la fibre est largement gouverné par la croissance de cette petite poche de gaz par diffusion du CO{2} dissous vers la poche. Nous avons démontré que la convection du liquide joue un rôle essentiel lors du transfert de masse du CO{2} dissous vers la poche. En effet, un modèle purement diffusif ne permet pas du tout de reproduire la dynamique de croissance expérimentale de ces poches de gaz piégées au cœur des fibres. Nous avons également pu mettre en évidence des changements spectaculaires dans la dynamique de bullage de certains sites de nucléation suivis au cours du temps pendant le processus de dégazage. Ces observations font de la fibre de cellulose immergée dans le champagne le plus petit système de bullage non-linéaire observé à ce jour. Dynamique ascensionnelle Pour mesurer la vitesse d'une bulle tout au long de son trajet vers la surface libre du champagne, nous avons tiré profit de la production répétitive de bulles au niveau des sites de nucléation. Par la mise en place d'un dispositif expérimental simple qui associe une lumière stroboscopique et un appareil photographique muni de bagues macros, nous avons pu accéder à l'observation fine des trains de bulles ainsi qu'à la détermination de la vitesse ascensionnelle des bulles. Les mesures expérimentales du rayon et de la vitesse d'une bulle nous ont permis de déterminer le coefficient de traînée d'une bulle montante qui constitue une mesure indirecte de son état de surface en termes de mobilité interfaciale. Ces mesures nous ont montré que l'interface d'une bulle de champagne conserve une grande mobilité interfaciale pendant sa phase ascensionnelle, à la différence des bulles de taille fixe qui montent dans une solution de macromolécules tensioactives. C'est la faible dilution du champagne en macromolécules tensioactives et le grossissement continu des bulles pendant l'ascension qui assurent aux bulles une faible contamination de leur interface. Pour comparaison, nous avons réalisé le même type de mesures sur des bulles de bière. Le contenu en macromolécules tensioactives étant beaucoup plus important dans une bière, l'effet de dilution du matériel tensioactif à la surface des bulles lié à l'accroissement de la surface des bulles ne compense plus l'adsorption massive des tensioactifs à la surface des bulles. Contrairement aux bulles du champagne, les bulles de bière adoptent vite un comportement de type sphère rigide. Nous avons également discuté l'influence relative de certains paramètres sur la taille des bulles lorsqu'elles parviennent en surface. Il a notamment été montré que le rôle théorique joué par la température du champagne sur la taille des bulles est quasiment négligeable. Pour finir, nous avons proposé d'essayer de faire du train de bulles une sorte d'empreinte digitale du liquide effervescent dans lequel il évolue en analysant la dynamique ascensionnelle des bulles via la mesure de leur coefficient de frottement. Nous avons pu différencier à ce jour par cette méthode trois grandes familles de boissons gazeuses : les vins effervescents au sens large (champagne compris), les bières et les eaux gazeuses. Éclatement En utilisant les techniques classiques de la macrophotographie, nous avons obtenu des instantanés de la situation qui suit immédiatement la rupture du mince film liquide qui constitue la partie émergée d'une bulle isolée en surface. Nous avons ainsi pu mettre en évidence l'existence des jets de liquide engendrés par les éclatements de bulle, et leur rupture en gouttelettes suite au développement très rapide de l'instabilité de Rayleigh-Plateau. En faisant un parallèle légitime entre le pétillement des bulles à la surface du champagne et le “pétillement de l'océan”, nous avons émis l'idée que les gouttelettes de jet étaient beaucoup plus concentrées en matériel tensioactif (et potentiellement aromatique) que le cœur de phase du liquide. Il semble donc que l'éclatement de bulles joue un rôle essentiel dans l'effet exhausteur d'arômes au cours de la dégustation d'un champagne. Pendant les quelques secondes qui suivent le versement du champagne dans la flûte, nous avons également réalisé des clichés macrophotographiques et des films à haute vitesse d'éclatements de bulles en monocouche (ou radeau de bulles). Les premiers résultats de ces observations font apparaître des déformations spectaculaires dans le film liquide des bulles premières voisines littéralement aspirées par succion capillaire dans la cavité laissée vacante par la bulle centrale en train d'éclater. Ces premières images suggèrent des contraintes, dans le mince film des bulles déformées, très supérieures à celles qui existent dans le sillage d'une bulle isolée qui éclate. Nous avons également pu mettre en évidence des différences structurales entre les jets de liquide qui suivent l'éclatement des bulles isolées et celles qui éclatent dans un radeau de bulles.

  5. La physique des bulles de champagne Une première approche des processus physico-chimiques liés à l'effervescence des vins de Champagne

    NASA Astrophysics Data System (ADS)

    Liger-Belair, G.

    2002-07-01

    People have long been fascinated by bubbles and foams dynamics, and since the pioneering work of Leonardo da Vinci in the early 16th century, this subject has generated a huge bibliography. However, only very recently, much interest was devoted to bubbles in Champagne wines. Small bubbles rising through the liquid, as well as a bubble ring (the so-called collar) at the periphery of a flute poured with champagne are the hallmark of this traditionally festive wine, and even there is no scientific evidence yet to connect the quality of a champagne with its effervescence, people nevertheless often make a connection between them. Therefore, since the last few years, a better understanding of the numerous parameters involved in the bubbling process has become an important stake in the champagne research area. Otherwise, in addition to these strictly enological reasons, we also feel that the area of bubble dynamics could benefit from the simple but close observation of a glass poured with champagne. In this study, our first results concerning the close observation of the three main steps of a champagne bubble's life are presented, that is, the bubble nucleation on tiny particles stuck on the glass wall (Chap. 2), the bubble ascent through the liquid (Chap. 3), and the bursting of bubbles at the free surface, which constitutes the most intriguing and visually appealing step (Chap. 4). Our results were obtained in real consuming conditions, that is, in a classical crystal flute poured with a standard commercial champagne wine. Champagne bubble nucleation proved to be a fantastic everyday example to illustrate the non-classical heterogeneous bubble nucleation process in a weakly supersaturated liquid. Contrary to a generally accepted idea, nucleation sites are not located on irregularities of the glass itself. Most of nucleation sites are located on tiny hollow and roughly cylindrical exogenous fibres coming from the surrounding air or remaining from the wiping process. Because of their geometry and hydrophobic properties, such particles are able to entrap gas pockets during the filling of a flute and to start up the bubble production process. Such particles are responsible for the clockwork and repetitive production of bubbles that rise in-line into the form of elegant bubble trains. This cycle of bubble production at a given nucleation site is characterised by its bubbling frequency. The time needed to reach the moment of bubble detachment depends on the kinetics of the CO2 molecules transfer from the champagne to the gas pocket, but also on the geometrical properties of the given nucleation site. Now, since a collection of particle shapes and sizes exists on the glass wall, the bubbling frequency may also vary from one site to another. Three minutes after pouring, we measured bubbling frequencies ranging from less than 1 Hz up to almost 30 Hz, which means that the most active nucleation sites emit up to 30 bubbles per second. After their detachment from nucleation sites, champagne bubbles rise in-line through the liquid into the form of elegant bubble trains. Since they collect dissolved carbon dioxide molecules, champagne bubbles expand during ascent and therefore constitute an original tool to investigate the dynamics of rising and expanding bubbles. Hydrodynamically speaking, champagne bubbles were found to reach a quasi-stationary stage intermediate between that of a rigid and that a fluid sphere (but nevertheless closer to that of a fluid sphere). This result drastically differs from the result classically observed with bubbles of fixed radii rising in surfactant solutions. Since surfactants progressively adsorb at the bubble surface during the rise, the drag coefficient of a rising bubble of fixed radius progressively increases, and finally reaches the rigid sphere limit when the bubble interface gets completely contaminated. In the case of champagne, since a bubble expands during its rise through the supersaturated liquid, the bubble interface continuously increases and therefore continuously offers newly created surface to the adsorbed surface-active materials (around 5 mg/l, mostly composed of proteins and glycoproteins). Champagne bubbles experience an interesting competition between two opposing effects. Our results suggest that the bubble growth during ascent approximately balance the adsorption rate of surface-active compounds on the rising bubble. We also compared the behaviour of champagne bubbles with that of beer bubbles. It was found that beer bubbles showed a behaviour, very close to that of rigid spheres. This is not a surprising result, since beer contains much higher amounts of surface-active molecules (of order of several hundreds mg/l) likely to be adsorbed at a bubble interface. Furthermore, since the gas content is lower in beer, growth rates of beer bubbles are lower than those of champagne. As a result, the dilution effect due to the rate of dilatation of the bubble area may be too weak to avoid the rigidification of the beer bubble interface. In a third set of experiments, we used instantaneous high-speed photography techniques to freeze the dynamics of bubbles collapsing at the free surface of a glass poured with champagne. The process following bubble collapse and leading to the projection of a high-speed liquid jet above the free surface was captured. A structural analogy between the liquid jet following a bubble collapse and the liquid jet following a drop impact was presented. By drawing a parallel between the fizz in champagne wines and the “fizz of the ocean", we also suggested that droplets issued from champagne bursting bubbles contain much higher amounts of surface-active and potentially aromatic materials than the liquid bulk. The bursting of champagne bubbles is thus expected to play a major role in flavour release. Otherwise, since the first photographic investigation were published about fifty years ago, numerous experiments have been conducted with single bubbles collapsing at a free surface. But, to the best of our knowledge, and surprising as it may seem, no results concerning the collateral effects on adjoining bubbles of bubbles collapsing in a bubble monolayer have been reported up to now. Actually, effervescence in a glass of champagne ideally lends to a preliminary work with bubbles collapsing in a bubble monolayer. For a few seconds after pouring, the free surface is completely covered with a monolayer composed of quite monodisperse millimetric bubbles collapsing close to each others. We took high-speed photographs of the situation which immediately follows the rupture of a bubble cap in a bubble monolayer. Adjoining bubbles were found to be literally sucked and strongly stretched toward the lowest part of the cavity left by the bursting bubble, leading to unexpected and short-lived flower-shaped structures. Stresses in distorted bubbles (petals of the flower-shaped structure) were evaluated and found to be, at least, one order of magnitude higher than stresses numerically calculated in the boundary layer around an isolated single millimetric collapsing bubble. This is a brand-new and slightly counter-intuitive result. While absorbing the energy released during collapse, as an air-bag would do, adjoining bubble caps store this energy into their thin liquid film, leading finally to stresses much higher than those observed in the boundary layer around single millimetric collapsing bubbles. Further investigation should be conducted now, and especially numerically, in order to better understand the relative influence of each pertinent parameters (bubble size, liquid density and viscosity, effect of surfactant...) on bubble deformation. L'objectif général de cet ouvrage consacré à l'étude des processus physico- chimiques de l'effervescence des vins de Champagne était de décortiquer les différentes étapes de la vie d'une bulle de champagne en conditions réelles de consommation, dans une flûte. Nous résumons ci-après les principaux résultats obtenus pour chacune des étapes de la vie de la bulle, depuis sa naissance sur les parois d'une flûte, jusqu'à son éclatement en surface. Naissance de la bulle À l'aide d'une caméra munie d'un objectif de microscope, nous avons pu mettre en évidence les particules qui jouent le rôle de sites de nucléation des bulles sur les parois d'une flûte à champagne. Dans la très grande majorité des cas, ce sont des fibres creuses et allongées, de quelques dizaines à quelques centaines de microns, qui assurent la production répétitive de bulles par nucléation hétérogène non classique (de type IV). Cette production répétitive de bulles au niveau des sites de nucléation est caractérisée par une gamme de fréquences de bullage assez large. Au sein d'une même flûte, immédiatement après le versement, nous avons mesuré des fréquences qui varient de moins de 1 Hz à presque 30 Hz. C'est donc jusqu'à 30 bulles qui sont émises chaque seconde par les sites de nucléation les plus actifs. Vitesse ascensionnelle d'une bulle Pour mesurer la vitesse d'une bulle tout au long de son trajet vers la surface libre du champagne, nous avons tiré profit de la production répétitive de bulles au niveau des sites de nucléation. Par la mise en place d'un dispositif expérimental simple qui associe une lumière stroboscopique et un appareil photographique muni de bagues macros, nous avons pu accéder à l'observation fine des trains de bulles ainsi qu'à la détermination de la vitesse ascensionnelle des bulles. Les mesures expérimentales du rayon et de la vitesse d'une bulle nous ont permis de déterminer le coefficient de traînée d'une bulle montante qui constitue une mesure indirecte de son état de surface en terme de mobilité interfaciale. Ces mesures nous ont montré que l'interface d'une bulle de champagne conserve une grande mobilité pendant sa phase ascensionnelle. C'est la faible dilution du champagne en macromolécules tensioactives et le grossissement continu des bulles pendant l'ascension qui assurent aux bulles une faible contamination de leur interface en molécules tensioactives. Pour comparaison, nous avons réalisé le même type de mesures sur des bulles de bière. Le contenu en macromolécules tensioactives étant beaucoup plus important dans une bière, l'effet de dilution du matériel tensioactif à la surface des bulles lié à l'accroissement de la surface des bulles ne compense plus l'adsorption massive des tensioactifs à la surface des bulles. Contrairement aux bulles du champagne, les bulles de bière adoptent vite un comportement de type sphère rigide. Éclatement d'une bulle en surface Nous avons obtenu des images de la situation qui suit immédiatement la rupture du mince film liquide qui constitue la partie émergée d'une bulle en surface. Nous avons ainsi pu mettre en évidence l'existence des jets de liquide engendrés par les éclatements de bulle. En faisant un parallèle légitime entre le pétillement des bulles à la surface du champagne et le "pétillement de l'océan", nous avons émis l'idée que les gouttelettes de jet étaient beaucoup plus concentrées en matériel tensioactif (et potentiellement aromatique) que le cœur de phase du liquide. Il semble donc que les éclatements de bulles jouent un rôle essentiel dans l'effet exhausteur d'arôme au cours de la dégustation d'un champagne. Pendant les quelques secondes qui suivent le versement du champagne dans la flûte, nous avons également réalisé des clichés d'éclatement de bulles en monocouche. Les premiers résultats de ces observations font apparaître des déformations spectaculaires dans le film liquide des bulles premières voisines. Ces premières images suggèrent des contraintes, dans le mince film des bulles déformées, très supérieures à celles qui existent dans le sillage d'une bulle isolée qui éclate.

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