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Sample records for fluorocarbons

  1. PRODUCTION OF FLUOROCARBONS

    DOEpatents

    Sarsfield, N.F.

    1949-06-21

    This patent pertains to a process for recovering fluorocarbons from a liquid mixture of hydrocarbons with partially and completely fluorinated products thereof. It consists of contacting the mxture in the cold with a liquid which is a solvent for the hydrocarbons and which is a nonsolvent for the fluorocarbons, extracting the hydrocarbons, separating the fluorocarbon-containing layer from the solvent-containing layer, and submitting the fluorocarbon layer to fractlonal distillation, to isolate the desired fluorocarbon fraction. Suitable solvents wnich may be used in the process include the lower aliphatic alcohols, and the lower aliphatic ketones.

  2. water-soluble fluorocarbon coating

    NASA Technical Reports Server (NTRS)

    Nanelli, P.

    1979-01-01

    Water-soluble fluorocarbon proves durable nonpolluting coating for variety of substrates. Coatings can be used on metals, masonry, textiles, paper, and glass, and have superior hardness and flexibility, strong resistance to chemicals fire, and weather.

  3. Industrial research on alternative fluorocarbons.

    PubMed

    Trochimowicz, H J

    1993-05-01

    Fluorocarbons containing chlorine or bromine have been associated with stratospheric ozone depletion and the search for suitable alternatives is progressing at an accelerated pace. The Program for Alternative Fluorocarbon Toxicity Testing (PAFT), an international group representing most of the world's CFC producers, has been conducting comprehensive toxicological evaluations on several possible replacements for current fire-extinguishing agents--1,1-dichloro-2,2,2-trifluoroethane (HCFC-123), 1-chloro-1,2,2,2-tetrafluoroethane (HCFC-124), pentafluoroethane (HFC-125), and 1-fluoro-2,2,2-trifluoroethane (HFC-134a). Results from short-term experimental studies showing a low order of acute toxicity, as well as results from longer-term toxicity studies on these replacements, will be discussed. PMID:8516770

  4. Fluorinated diamond bonded in fluorocarbon resin

    DOEpatents

    Taylor, Gene W.

    1982-01-01

    By fluorinating diamond grit, the grit may be readily bonded into a fluorocarbon resin matrix. The matrix is formed by simple hot pressing techniques. Diamond grinding wheels may advantageously be manufactured using such a matrix. Teflon fluorocarbon resins are particularly well suited for using in forming the matrix.

  5. Extending TEWI to production of fluorocarbons

    SciTech Connect

    Banks, R.E.; Sharratt, P.N.; Johnson, E.P.; Clarke, E.K.

    1996-12-31

    In many analyses of Total Environment Warming Impact (TEWI) that involve fluorocarbons, the release of the end-product fluorocarbon to atmosphere--for instance, venting from a used refrigeration unit--is the only global warming that is considered. For fluorochemicals where the end-product is not even a global warmer itself, production may be the stage of the life-cycle where global warming is greatest. Thus, a TEWI comparison of two systems involving fluorocarbons that ignores the production stage may be inaccurate. This paper illustrates the above in three parts: (1) An overview of fluorocarbon manufacturing, focusing on key global warmers; (2) a closer, step-by-step examination of the manufacturing chain for hexafluoropropene (HFP), with quantification of the global warmers and ozone depletors emitted; and (3) presentation of the TEWI calculations and results for HFP, split into two types of contributions: (1) fluorocarbon and (2) energy/transport.

  6. A new fluorocarbon for keratoprosthesis.

    PubMed

    Legeais, J M; Rossi, C; Renard, G; Salvoldelli, M; D'Hermies, F; Pouliquen, Y J

    1992-11-01

    Previous studies have demonstrated the potential use of microporous, biocompatible materials to improve the long-term stability of keratoprosthesis. To determine the factors that will influence corneal tissue ingrowth into biocompatible, microporous materials, we have compared three types of fluorocarbon polymers--Impra, Gore-Tex, and Proplast--after intrastromal implantation in rabbit corneas. Despite similar physicochemical structures, a great difference was observed in histologic and ultrastructural cross sections after 4- and 8-month follow-ups. For Gore-Tex, we observed extrusion of the implant and infiltration of necrotic and inflammatory cells. All implants of Proplast also led to significant corneal damage resulting in extrusion of the material. Through the use of electron and light microscopy and image analysis, this study demonstrates the presence of cell differentiation and collagen synthesis in the pores of the Impra implant. Apart from biocompatibility, this experiment demonstrates the influence of pore size, porous microorganization, and biomechanical factors on prosthetic corneal material. Only Impra offers satisfactory interface, allowing fibroblastic cells and neocollagen synthesis into its pores, and it can become transparent. PMID:1468216

  7. Vapor pressures of new fluorocarbons

    SciTech Connect

    Kubota, H.; Yamashita, T.; Tanaka, Y.; Makita, T. )

    1989-05-01

    The vapor pressures of four fluorocarbons have been measured at the following temperature ranges: R123 (2,2-dichloro-1,1,1-trifluoroethane), 273-457 K; R123a (1,2-dichloro-1,1,2-trifluoroethane), 303-458 K; R134a (1,1,1,2-tetrafluoroethane), 253-373 K; and R132b (1,2-dichloro-1,1-difluoroethane), 273-398 K. Determinations of the vapor pressure were carried out by a constant-volume apparatus with an uncertainty of less than 1.0%. The vapor pressures of R123 and R123a are very similar to those of R11 over the whole experimental temperature range, but the vapor pressures of R134a and R132b differ somewhat from those of R12 and R113, respectively, as the temperature increases. The numerical vapor pressure data can be fitted by an empirical equation using the Chebyshev polynomial with a mean deviation of less than 0.3%.

  8. Fluorocarbon Adsorption in Hierarchical Porous Frameworks

    SciTech Connect

    Motkuri, Radha K.; Annapureddy, Harsha V.; Vijayakumar, M.; Schaef, Herbert T.; Martin, P F.; McGrail, B. Peter; Dang, Liem X.; Krishna, Rajamani; Thallapally, Praveen K.

    2014-07-09

    The adsorption behavior of a series of fluorocarbon derivatives was examined on a set of microporous metal organic framework (MOF) sorbents and another set of hierarchical mesoporous MOFs. The microporous M-DOBDC (M = Ni, Co) showed a saturation uptake capacity for R12 of over 4 mmol/g at a very low relative saturation pressure (P/Po) of 0.02. In contrast, the mesoporous MOF MIL-101 showed an exceptionally high uptake capacity reaching over 14 mmol/g at P/Po of 0.4. Adsorption affinity in terms of mass loading and isosteric heats of adsorption were found to generally correlate with the polarizability of the refrigerant with R12 > R22 > R13 > R14 > methane. These results suggest the possibility of exploiting MOFs for separation of azeotropic mixtures of fluorocarbons and use in eco-friendly fluorocarbon-based adsorption cooling and refrigeration applications.

  9. A unique type of fluorocarbon elastomer

    SciTech Connect

    Eggers, R.E.

    1991-06-01

    This article examines the mechanical and chemical properties of the fluorocarbon elastomer Aflas tetrafluoroethylene (TFE/P) based on the monomers tetrafluoroethylene (TFE) and propylene (P). Topics discussed include TFE/P elastomer products, compounding TFE/P elastomers, polymer selection, reinforcing fillers, peroxide vulcanizing agents, coagents, process aids, processing TFE/P elastomers, and applications for the use of TFE/P elastomers.

  10. Fluorocarbon nanodrops as acoustic temperature probes.

    PubMed

    Mountford, Paul A; Smith, William S; Borden, Mark A

    2015-10-01

    This work investigated the use of superheated fluorocarbon nanodrops for ultrasound thermal imaging and the use of mixed fluorocarbons for tuning thermal and acoustic thresholds for vaporization. Droplets were fabricated by condensing phospholipid-coated microbubbles containing C3F8 and C4F10 mixed at various molar ratios. Vaporization temperatures first were measured in a closed system by optical transmission following either isothermal pressure release or isobaric heating. The vaporization temperature was found to depend linearly on the percentage of C4F10 in the droplet core, indicating excellent tunability under these fluorocarbon-saturated conditions. Vaporization temperatures were then measured in an open system using contrast-enhanced ultrasound imaging, where it was found that the mixed droplets behaved like pure C4F10 drops. Additionally, the critical mechanical index for vaporization was measured at the limits of therapeutic hyperthermia (37 and 60 C), and again the mixed droplets were found to behave like pure C4F10 drops. These results suggested that C3F8 preferentially dissolves out of the droplet core in open systems, as shown by a simple mass transfer model of multicomponent droplet dissolution. Finally, proof-of-concept was shown that pure C4F10 nanodrops can be used as an acoustic temperature probe. Overall, these results not only demonstrate the potential of superheated fluorocarbon emulsions for sonothermetry but also point to the limits of tunability for fluorocarbon mixtures owing to preferential release of the more soluble species to the atmosphere. PMID:26359919

  11. Fluorocarbon adsorption in hierarchical porous frameworks

    SciTech Connect

    Motkuri, RK; Annapureddy, HVR; Vijaykumar, M; Schaef, HT; Martin, PF; McGrail, BP; Dang, LX; Krishna, R; Thallapally, PK

    2014-07-09

    Metal-organic frameworks comprise an important class of solid-state materials and have potential for many emerging applications such as energy storage, separation, catalysis and bio-medical. Here we report the adsorption behaviour of a series of fluorocarbon derivatives on a set of microporous and hierarchical mesoporous frameworks. The microporous frameworks show a saturation uptake capacity for dichlorodifluoromethane of >4 mmol g(-1) at a very low relative saturation pressure (P/P-o) of 0.02. In contrast, the mesoporous framework shows an exceptionally high uptake capacity reaching >14 mmol g(-1) at P/P-o of 0.4. Adsorption affinity in terms of mass loading and isosteric heats of adsorption is found to generally correlate with the polarizability and boiling point of the refrigerant, with dichlorodifluoromethane >chlorodifluoromethane >chlorotrifluoromethane >tetrafluoromethane >methane. These results suggest the possibility of exploiting these sorbents for separation of azeotropic mixtures of fluorocarbons and use in eco-friendly fluorocarbon-based adsorption cooling.

  12. Dry cleaning of fluorocarbon residues by atomic hydrogen flow

    NASA Astrophysics Data System (ADS)

    Anishchenko, E.; Diamant, V.; Kagadei, Valerii A.; Nefeyodtsev, E.; Proskurovsky, Dmitry I.; Romanenko, S.

    2004-05-01

    Successful removal of fluorocarbon residues on silicon structure using neutral atomic hydrogen direct flow is reported. It has been stated that the treatment of samples in atomic hydrogen direct flow of density of 2x1015 at. cm-2 s-1 leads to decreasing of fluorocarbon residues concentration on the surface of structure by 5 orders of magnitude. The concentration of fluorocarbon residues after AH treatment is at the hum level characteristic for the absolutely clean surface exposed in atmosphere air. Removal fluorocarbon residues is being realized at temperature of 20-100 ° both from the planar surface of a structure and from the sidewalls and bottom of the contact holes with diameter of 0.3-0.25 μm and depth of 1.2-1 μm. The time of treatment as 2 min is quite sufficient for fluorocarbon residues removal.

  13. Piezoelectric activity and thermal stability of cellular fluorocarbon films

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoqing; Huang, Jinfeng; Xia, Zhongfu

    2007-12-01

    Two methods for preparing piezoelectric fluorocarbon polymers with cellular structure (ferroelectrets) are introduced. Piezoelectric activity of laminated fluorocarbon films made from polytetrafluoroethylene (PTFE) and fluoroethylenepropylene (FEP) is characterized by quasistatic measurement of piezoelectric d33 coefficient, while the thermal stability of d33 is investigated by their isothermal decay. The results show that the quasistatic d33-coefficients between 500 and 2200 pC/N are obtained for such fluorocarbon films; d33-coefficients are relatively independent of the static pressure in the range of 20 kPa; comparing to cellular polypropylene (PP) film the new fluorocarbon films show not only higher values of d33, but also much better thermal stability; moreover, thermal stability of the fluorocarbon film can be further improved by the process of pre-ageing.

  14. Fluorinated diamond particles bonded in a filled fluorocarbon resin matrix

    DOEpatents

    Taylor, G.W.; Roybal, H.E.

    1983-11-14

    A method of producing fluorinated diamond particles bonded in a filled fluorocarbon resin matrix. Simple hot pressing techniques permit the formation of such matrices from which diamond impregnated grinding tools and other articles of manufacture can be produced. Teflon fluorocarbon resins filled with Al/sub 2/O/sub 3/ yield grinding tools with substantially improved work-to-wear ratios over grinding wheels known in the art.

  15. Fluorinated diamond particles bonded in a filled fluorocarbon resin matrix

    DOEpatents

    Taylor, Gene W.; Roybal, Herman E.

    1985-01-01

    A method of producing fluorinated diamond particles bonded in a filled fluorocarbon resin matrix. Simple hot pressing techniques permit the formation of such matrices from which diamond impregnated grinding tools and other articles of manufacture can be produced. Teflon fluorocarbon resins filled with Al.sub.2 O.sub.3 yield grinding tools with substantially improved work-to-wear ratios over grinding wheels known in the art.

  16. Fluorocarbon compounds in MRI diagnostics and medical therapy

    NASA Astrophysics Data System (ADS)

    Pirogov, Yu

    2016-02-01

    The lecture describes the application of fluorocarbon compounds as blood substitutes and contrasting preparations in MRI diagnostics. A blood substitute product fluorocarbon Perfluorane® has shown effectiveness in oxygen delivery to the tissues of living organisms, and cardioprotective effect which does not depend on the patient's blood group. Inclusion of paramagnetic atoms (gadolinium, iron, etc.) to the Perfluorane® chemical formula creates a new compound with high MRI contrast efficiencies at Larmor frequencies of protons so and fluorine-19 nuclei.

  17. Thermodynamic properties of gaseous fluorocarbons and isentropic equilibrium expansions of two binary mixtures of fluorocarbons and argon

    NASA Technical Reports Server (NTRS)

    Talcott, N. A., Jr.

    1977-01-01

    Equations and computer code are given for the thermodynamic properties of gaseous fluorocarbons in chemical equilibrium. In addition, isentropic equilibrium expansions of two binary mixtures of fluorocarbons and argon are included. The computer code calculates the equilibrium thermodynamic properties and, in some cases, the transport properties for the following fluorocarbons: CCl2F, CCl2F2, CBrF3, CF4, CHCl2F, CHF3, CCL2F-CCl2F, CCLF2-CClF2, CF3-CF3, and C4F8. Equilibrium thermodynamic properties are tabulated for six of the fluorocarbons(CCl3F, CCL2F2, CBrF3, CF4, CF3-CF3, and C4F8) and pressure-enthalpy diagrams are presented for CBrF3.

  18. Effect of fluorocarbons on acetylcholinesterase activity and some counter measures

    NASA Technical Reports Server (NTRS)

    Young, W.; Parker, J. A.

    1975-01-01

    An isolated vagal sympathetic heart system has been successfully used for the study of the effect of fluorocarbons (FCs) on cardiac performance and in situ enzyme activity. Dichlorodifluoromethane sensitizes this preparation to sympathetic stimulation and to exogenous epinephrine challenge. Partial and complete A-V block and even cardiac arrest have been induced by epinephrine challenge in the FC sensitized heart. Potassium chloride alone restores the rhythmicity but not the normal contractility of the heart in such a situation. Addition of glucose will, however, completely restore the normal function of the heart which is sensitized by dichlorodifluoromethane. The ED 50 values of acetylcholinesterase activity which are used as a measure of relative effectiveness of fluorocarbons are compared with the maximum permissible concentration. Kinetic studies indicate that all the fluorocarbons tested so far are noncompetitive.

  19. Cause and Effects of Fluorocarbon Degradation in Electronics and Opto-Electronic Systems

    NASA Technical Reports Server (NTRS)

    Predmore, Roamer E.; Canham, John S.

    2002-01-01

    Trace degradation of fluorocarbon or halocarbon materials must be addressed in their application in sensitive systems. As the dimensions and/or tolerances of components in a system decrease, the sensitivity of the system to trace fluorocarbon or halocarbon degradation products increases. Trace quantities of highly reactive degradation products from fluorocarbons have caused a number of failures of flight hardware. It is of utmost importance that the risk of system failure, resulting from trace amounts of reactive fluorocarbon degradation products be addressed in designs containing fluorocarbon or halocarbon materials. Thermal, electrical, and mechanical energy input into the system can multiply the risk of failure.

  20. Gain and loss mechanisms in fluorocarbon plasmas

    NASA Astrophysics Data System (ADS)

    Nelson, Caleb Timothy

    Understanding dominant reaction channels for important gas-phase species in fluorocarbon plasmas is crucial to the ability to control surface evolution and morphology. In order to accomplish this goal a modified GEC reference ICP reactor is used in tandem with Fourier transform infrared spectroscopy (FTIR) to measure the densities of stable species. Integrated absorption cross-sections are presented for all fundamental bands in the 650 cm-1 to 2000 cm-1 region for C3F6, C4F 8, C3F8, C2F6, C2F 4, and CF4. The results show that although the absorption profile changes significantly, the integrated absorption cross-sections, with the exception of CF4, do not change significantly as gas temperature increases from 25°C to 200°C. However, the internal temperature of the absorbing species can be estimated from the rotational band maximum in most cases. Species densities obtained with the aforementioned cross-sections are used with a novel analysis technique to quantify gain and loss rates as functions of residence time, pressure, and deposited power. CF4, C2F6, C3F8, and C4F 10, share related production channels, which increase in magnitude as the plasma pressure, deposited power, or surface temperature are raised. CF 2 is primarily produced through a combination of surface production (the magnitude also increases with temperature) and electron impact dissociation of C2F4, while it is predominantly lost in the large reactor to gas-phase addition to form C2F4. Time-resolved FTIR results are used to measure a cross-section of 1.8x10-14 cm3/s for the reaction between CF2 radicals creating C2F4. Finally, C2F4 originates through the electron impact dissociation of c- C4F8. The loss process for C2F4 is undetermined, but the results indicate that it could occur on reactor surfaces. Neither the density of fluorine nor the ion flux to the chuck surface changes substantially with wall temperature. We show that increases in the deposition rate in a heated chamber are due to an increase in the fluxes of depositing neutral species. Furthermore, the sticking coefficient for these species does not change significantly as a function of surface temperature. Instead, surface temperature elevates the yield of etchant species, which terminate broken bonds to increase the desorption rates of stable species.

  1. METHOD FOR DETERMINING THE STABILITY OF FLUOROCARBON IOLS

    DOEpatents

    Sheldon, Z.D.; Haendler, H.M.

    1959-07-21

    A method of determining the stability of a fluorocarbon oil to uranium hexafluoride is presented. The method comprises reacting a weighed sample of the oil with condensed uranium hexafluoride in a reaction zone and titrating the amount of uranium tetrafluoride produced with potassium dichromate.

  2. Method and means for producing fluorocarbon finishes on fibrous structures

    NASA Technical Reports Server (NTRS)

    Toy, Madeline S. (Inventor); Stringham, Roger S. (Inventor); Fogg, Lawrence C. (Inventor)

    1981-01-01

    An improved process and apparatus is provided for imparting chemically bonded fluorocarbon finishes to textiles. In the process, the textiles are contacted with a gaseous mixture of fluoroolefins in an inert diluent gas in the presence of ultraviolet light under predetermined conditions.

  3. The Effect of Moisture Content on Retention of Fluorocarbon Tracers on Sand

    SciTech Connect

    B. T. Maxfield; D. M. Ginosar; R. D. McMurtrey; H. W. Rollins; G. M. Shook

    2005-02-01

    Several fluorocarbon compounds have been evaluated as geothermal tracers in sand column tests using damp, dry, and untreated ‘washed sea sand’. Fluorocarbons evaluated in these tests included two hydrofluorocarbon freons: trifluoromethane (R23) and 1,1,1,2-tetrafluoroethane (R134a), and five perfluorocarbons: perfluorodimethylcyclobutane, perfluoromethylcyclopentane, perfluoromethylcyclohexane, perfluorodimethylcyclohexane and perfluorotrimethylcyclohexane. Transport of the fluorocarbon compounds was explored in flowing helium at 23 and 60 °C. This work found that fluorocarbon retention is strongly affected by sand moisture content. The fluorocarbon compounds flowed with the bulk fluid when the sand was damp, but were significantly retained by the solid phase when the sand was thoroughly dried. The data suggest that the fluorocarbons may be conservative tracers in geothermal conditions up to mild superheat but they may not be conservative at geothermal conditions with a high degree of superheat.

  4. Spraylon fluorocarbon encapsulation for silicon solar cell arrays

    NASA Technical Reports Server (NTRS)

    1977-01-01

    A development program was performed for evaluating, modifying, and optimizing the Lockheed formulated liquid transparent filmforming Spraylon fluorocarbon protective coating for silicon solar cells and modules. The program objectives were designed to meet the requirements of the low-cost automated solar cell array fabrication process. As part of the study, a computer program was used to establish the limits of the safe working stress in the coated silicon solar cell array system under severe thermal shock.

  5. Reactive airways dysfunction syndrome following exposure to a fluorocarbon.

    PubMed

    de la Hoz, R E

    1999-05-01

    This report describes the case of a 43-yr-old male who developed reactive airways dysfunction syndrome after exposure to a high level of bromotrifluoromethane (CF3Br, Halon 1301), a fluorocarbon widely used in automatic fire extinguishing systems. The patient was a previously healthy, nonatopic male, who developed wheezing and intermittent and reversible obstructive ventilatory impairment starting immediately after a large accidental nonfire-related release of CF3Br in a confined space. PMID:10414425

  6. Reaction of uranium and the fluorocarbon FC-75

    NASA Astrophysics Data System (ADS)

    Young, R. H.

    1985-04-01

    Because of criticality concerns with water cooling in enriched uranium upgrading, a fluorocarbon has been evaluated as a replacement coolant for internal module components in the Plasma Separation Process (PSP). The interaction of bulk uranium and of powdered uranium with FC-75 has been investigated at temperatures between 200 and 700 C. The gas pressure and the metal temperature were monitored as a function of time. Modest temperature changes of 50 to 100 C were observed for the bulk uranium/fluorocarbon reaction. Much larger changes (up to 1000 C) were noted for the reaction involving high surface area uranium powder. These temperature transients, particularly for the powdered uranium reaction, were short-lived ( 10 seconds) and indicative of the formation of a protective layer of reaction products. Analysis of residual gas products by infrared spectroscopy indicated that one potentially serious hazard, UF6, was not present; however, several small toxic fluorocarbons were produced by thermolysis and/or reaction. X-ray diffraction analysis of the residual solids indicated UF4 and UO2 were the major solid products.

  7. Spraylon fluorocarbon encapsulation for silicon solar cell arrays, phase 3

    NASA Technical Reports Server (NTRS)

    Naes, L. G.

    1978-01-01

    The liquid transparent film-forming, fluorocarbon, Spraylon, a protective coating for terrestrial solar cell modules was evaluated. Two modules were completed and field tested. Problems developed early in the field testing which led to the shortened test period, specifically, lifting of the antireflection coating, followed in some areas by complete film delamination. It is believed that although these problems were certainly induced by the presence of the SPRAYLON film, they were not failures of the material per se. Instead, assembly procedures, module design, and cell coating quality should be evaluated to determine cause of failure.

  8. Fluorocarbon 113 exposure and cardiac dysrhythmias among aerospace workers.

    PubMed

    Egeland, G M; Bloom, T F; Schnorr, T M; Hornung, R W; Suruda, A J; Wille, K K

    1992-01-01

    We investigated the cardiotoxic effects of 1,1,2-Trichloro-1,2,2- Trifluoroethane (fluorocarbon 113 or FC113) exposures among healthy workers cleaning rocket and ground support equipment for the National Aeronautic and Space Administration (NASA) programs. Exposure and ambulatory electrocardiographic (ECG) monitoring data were evaluated on 16 workers, each of whom was examined on exposed and nonexposed workdays. We examined whether there was a greater rate of dysrhythmias on an exposed workday relative to a nonexposed workday. Overall, we found no within subject differences in the rate of ventricular and supraventricular premature beats (number per 1,000 heart beats), fluctuations in the length of the P-R interval, or heart rate. We found that levels of FC113 exposures below the Occupational Safety and Health Administration (OSHA) 8-hour time-weighted-average (TWA) standard of 1,000 ppm did not induce cardiac dysrhythmias or subtle changes in cardiac activity. However, because fluorocarbons may sensitize the heart to epinephrine, this study's negative findings based on sedentary and fairly healthy workers may not be generalizable to other populations of workers who are not as healthy or engaged in more physically demanding work. PMID:1463030

  9. Roughness assessment and wetting behavior of fluorocarbon surfaces.

    PubMed

    Terriza, Antonia; Álvarez, Rafael; Borrás, Ana; Cotrino, José; Yubero, Francisco; González-Elipe, Agustín R

    2012-06-15

    The wetting behavior of fluorocarbon materials has been studied with the aim of assessing the influence of the surface chemical composition and surface roughness on the water advancing and receding contact angles. Diamond like carbon and two fluorocarbon materials with different fluorine content have been prepared by plasma enhanced chemical vapor deposition and characterized by X-ray photoemission, Raman and FT-IR spectroscopies. Very rough surfaces have been obtained by deposition of thin films of these materials on polymer substrates previously subjected to plasma etching to increase their roughness. A direct correlation has been found between roughness and water contact angles while a superhydrophobic behavior (i.e., water contact angles higher than 150° and relatively low adhesion energy) was found for the films with the highest fluorine content deposited on very rough substrates. A critical evaluation of the methods currently used to assess the roughness of these surfaces by atomic force microscopy (AFM) has evidenced that calculated RMS roughness values and actual surface areas are quite dependent on both the scale of observation and image resolution. A critical discussion is carried out about the application of the Wenzel model to account for the wetting behavior of this type of surfaces. PMID:22483335

  10. Enhanced removal of radioactive particles by fluorocarbon surfactant solutions

    SciTech Connect

    Kaiser, R.; Harling, O.K.

    1993-08-01

    The proposed research addressed the application of ESI`s particle removal process to the non-destructive decontamination of nuclear equipment. The cleaning medium used in this process is a solution of a high molecular weight fluorocarbon surfactant in an inert perfluorinated liquid which results in enhanced particle removal. The perfluorinated liquids of interest, which are recycled in the process, are nontoxic, nonflammable, and environmentally compatible, and do not present a hazard to the ozone layer. The information obtained in the Phase 1 program indicated that the proposed ESI process is technically effective and economically attractive. The fluorocarbon surfactant solutions used as working media in the ESI process survived exposure of up to 10 Mrad doses of gamma rays, and are considered sufficiently radiation resistant for the proposed process. Ultrasonic cleaning in perfluorinated surfactant solutions was found to be an effective method of removing radioactive iron (Fe 59) oxide particles from contaminated test pieces. Radioactive particles suspended in the process liquids could be quantitatively removed by filtration through a 0.1 um membrane filter. Projected economics indicate a pre-tax pay back time of 1 month for a commercial scale system.

  11. Application of cyclic fluorocarbon/argon discharges to device patterning

    SciTech Connect

    Metzler, Dominik; Uppiredi, Kishore; Bruce, Robert L.; Miyazoe, Hiroyuki; Zhu, Yu; Price, William; Sikorski, Ed S.; Li, Chen; Engelmann, Sebastian U.; Joseph, Eric A.; Oehrlein, Gottlieb S.

    2015-11-13

    With increasing demands on device patterning to achieve smaller critical dimensions and pitches for the 5nm node and beyond, the need for atomic layer etching (ALE) is steadily increasing. In this study, a cyclic fluorocarbon/Ar plasma is successfully used for ALE patterning in a manufacturing scale reactor. Self-limited etching of silicon oxide is observed. The impact of various process parameters on the etch performance is established. The substrate temperature has been shown to play an especially significant role, with lower temperatures leading to higher selectivity and lower etch rates, but worse pattern fidelity. The cyclic ALE approach established with this work is shown to have great potential for small scale device patterning, showing self-limited etching, improved uniformity and resist mask performance.

  12. Application of cyclic fluorocarbon/argon discharges to device patterning

    DOE PAGESBeta

    Metzler, Dominik; Uppiredi, Kishore; Bruce, Robert L.; Miyazoe, Hiroyuki; Zhu, Yu; Price, William; Sikorski, Ed S.; Li, Chen; Engelmann, Sebastian U.; Joseph, Eric A.; et al

    2015-11-13

    With increasing demands on device patterning to achieve smaller critical dimensions and pitches for the 5nm node and beyond, the need for atomic layer etching (ALE) is steadily increasing. In this study, a cyclic fluorocarbon/Ar plasma is successfully used for ALE patterning in a manufacturing scale reactor. Self-limited etching of silicon oxide is observed. The impact of various process parameters on the etch performance is established. The substrate temperature has been shown to play an especially significant role, with lower temperatures leading to higher selectivity and lower etch rates, but worse pattern fidelity. The cyclic ALE approach established with thismore » work is shown to have great potential for small scale device patterning, showing self-limited etching, improved uniformity and resist mask performance.« less

  13. Potential use of fluorocarbons in lung surfactant therapy.

    PubMed

    Gerber, Frédéric; Krafft, Marie Pierre; Vandamme, Thierry F; Goldmann, Michel; Fontaine, Philippe

    2007-01-01

    Exogenous surfactant therapy based on animal lung extract preparations has been developed successfully for the treatment of neonatal respiratory distress syndrome. However, because of the inherent limitations of these natural preparations, the development of new synthetic surfactants is a major objective. We report here that a perfluorocarbon gas (perfluorooctyl bromide, gPFOB) inhibits the formation of the semi-crystalline domains that occur during compression of a Langmuir monolayer of dipalmitoyl phosphatidylcholine (DPPC), taken as a simplified model of lung surfactant. gPFOB also facilitates the re-spreading of the DPPC monolayer. These results suggest that PFOB, a fluorocarbon already investigated for oxygen delivery, may be useful in lung surfactant replacement compositions. PMID:17453705

  14. Marine biofouling on the fluorocarbon coatings comprising PTFE powders

    NASA Astrophysics Data System (ADS)

    Zhang, Zhan-ping; Qi, Yu-hong; Liu, Hong; Zhang, Zheng

    2009-07-01

    Fluorocarbon coatings were developed with respectively 10%, 20% and 30% PTFE powder to prevent marine biofouling. Influence of content of PTFE on microstructures and roughness of coatings was investigated using SEM and roughometer. It was studied that the effects of coating roughness on settlement of benthic diatom and Ectocarpus by using biological microscope, stereo microscope, image processing and spectrophotometer. Results indicated that the surface roughness of coatings decreases and the quantity of benthic diatom and Ectocarpus reduces attaching onto the coating with the increase of content of PTFE in paint studied. Benthic diatoms attached much more on horizontal specimen than on vertical one; they prefer to settle onto the coatings that there are lots of micro-cracks in it. These results are helpful for developing new non-toxic antifouling paints.

  15. Selective Plasma Deposition of Fluorocarbon Films on SAMs

    NASA Technical Reports Server (NTRS)

    Crain, Mark M., III; Walsh, Kevin M.; Cohn, Robert W.

    2006-01-01

    A dry plasma process has been demonstrated to be useful for the selective modification of self-assembled monolayers (SAMs) of alkanethiolates. These SAMs are used, during the fabrication of semiconductor electronic devices, as etch masks on gold layers that are destined to be patterned and incorporated into the devices. The selective modification involves the formation of fluorocarbon films that render the SAMs more effective in protecting the masked areas of the gold against etching by a potassium iodide (KI) solution. This modification can be utilized, not only in the fabrication of single electronic devices but also in the fabrication of integrated circuits, microelectromechanical systems, and circuit boards. In the steps that precede the dry plasma process, a silicon mold in the desired pattern is fabricated by standard photolithographic techniques. A stamp is then made by casting polydimethylsiloxane (commonly known as silicone rubber) in the mold. The stamp is coated with an alkanethiol solution, then the stamp is pressed on the gold layer of a device to be fabricated in order to deposit the alkanethiol to form an alkanethiolate SAM in the desired pattern (see figure). Next, the workpiece is exposed to a radio-frequency plasma generated from a mixture of CF4 and H2 gases. After this plasma treatment, the SAM is found to be modified, while the exposed areas of gold remain unchanged. This dry plasma process offers the potential for forming masks superior to those formed in a prior wet etching process. Among the advantages over the wet etching process are greater selectivity, fewer pin holes in the masks, and less nonuniformity of the masks. The fluorocarbon films formed in this way may also be useful as intermediate layers for subsequent fabrication steps and as dielectric layers to be incorporated into finished products.

  16. Tunable hydrophilicity on a hydrophobic fluorocarbon polymer coating on silicon

    SciTech Connect

    Kolari, K.; Hokkanen, A.

    2006-07-15

    An efficient, economic, reliable, and repeatable patterning procedure of hydrophobic surfaces was developed. A fluorocarbon polymer derived from the C{sub 4}F{sub 8} gas in an inductively coupled plasma etcher was used as the hydrophobic coating. For a subsequent patterning of hydrophilic apertures on the polymer, a short O{sub 2} plasma exposure through a silicon shadow mask was utilized. The overall hydrophilicity of the patterned surface can be tuned by the duration of the O{sub 2} plasma exposure, and also by the density and the size of the hydrophilic apertures. The laborious photolithography and tricky lift-off procedures are avoided. Optimization of the whole patterning process is explained thoroughly and supported with experimental data. The hydrophilic adhesion of the patterned polymer was evaluated with aqueous droplets, which were studied on matrices of the hydrophilic apertures of different sizes. The deposition parameters of the fluorocarbon polymer, the size of the droplet required to enable rolling on the patterned surface, and the duration of the O{sub 2} plasma exposure were considered as the main parameters. To determine the achievable resolution of the patterning procedure, the subsurface etching beneath the shadow mask was evaluated. The results show that a resolution of less than 10 {mu}m can be achieved. The simple hydrophilic patterning procedure described here can be used for the production of on-plane microfluidics, where a controlled adhesion or decohesion of 8-50 {mu}l droplets on the surface with a variable hydrophilicity from one location to another can be achieved.

  17. Electron Attachment to Fluorocarbon Radicals and Unstable Molecules: CF2 and C2F5

    NASA Astrophysics Data System (ADS)

    Field, T. A.; Graupner, K.; Haughey, S.; Mayhew, C. A.; Shuman, N. S.; Miller, T. M.; Friedman, J. F.; Viggiano, A. A.

    2012-11-01

    Electron attachment to unstable fluorocarbon molecules has been investigated; CF2 - no dissociative electron attachment was observed, C2F5 - electron attachment observed at close to zero electron energy with the observation of C2F5-.

  18. Improvement of adhesion strength and scratch resistance of fluorocarbon thin films by cryogenic treatment

    NASA Astrophysics Data System (ADS)

    Jiang, Xiaojun; Wang, Jun; Shen, Jinpeng; Li, Rui; Yang, Guangcheng; Huang, Hui

    2014-01-01

    Fluorocarbon thin films have been widely applied as protective coatings due to unique physical and chemical properties, but the scratch resistance and adhesion strength between the films and substrates are rather poor. Coating technologies for stronger scratch resistance and adhesion strength are definitely needed and have great significance in coatings applications of fluorocarbon thin films. In this work, the scratch resistance and adhesion strength between silicon substrates and fluorocarbon thin films deposited by radio frequency (R.F.) magnetron sputtering were improved via a remarkably simple, flexible and nondestructive cryogenic treatment method. The effect of the cryogenic treatment on the microstructure, hardness, adhesion strength and scratch resistance of fluorocarbon thin films were investigated. XPS results indicated that the content of fluorine decreased slightly and the amount of cross-linked units increased after cryogenic treatment. Furthermore, the hardness of fluorocarbon thin films slightly improved. Nano-scratch test revealed that fluorocarbon thin films after this treatment had excellent scratch resistance and good adhesion strength.

  19. Roughening of porous SiCOH materials in fluorocarbon plasmas

    NASA Astrophysics Data System (ADS)

    Bailly, F.; David, T.; Chevolleau, T.; Darnon, M.; Posseme, N.; Bouyssou, R.; Ducote, J.; Joubert, O.; Cardinaud, C.

    2010-07-01

    Porous SiCOH materials integration for integrated circuits faces serious challenges such as roughening during the etch process. In this study, atomic force microscopy is used to investigate the kinetics of SiCOH materials roughening when they are etched in fluorocarbon plasmas. We show that the root mean square roughness and the correlation length linearly increase with the etched depth, after an initiation period. We propose that: (1) during the first few seconds of the etch process, the surface of porous SiCOH materials gets denser. (2) Cracks are formed, leading to the formation of deep and narrow pits. (3) Plasma radicals diffuse through those pits and the pore network and modify the porous material at the bottom of the pits. (4) The difference in material density and composition between the surface and the bottom of the pits leads to a difference in etch rate and an amplification of the roughness. In addition to this intrinsic roughening mechanism, the presence of a metallic mask (titanium nitride) can lead to an extrinsic roughening mechanism, such as micromasking caused by metallic particles originating form the titanium nitride mask.

  20. Myocardial oxygen tensions during ischaemia in fluorocarbon diluted pigs.

    PubMed

    Faithfull, N S; Fennema, M; Erdmann, W

    1988-01-01

    Previous work by the authors has shown that, following ligation of the left anterior descending coronary artery (LAD), myocardial oxygen tension (PmO2) in expected areas of maximal ischaemia is maintained at the expense of ischaemic border zones of the infarct area. Post-ischaemic haemodilution with the fluorocarbon containing plasma substitute Fluosol-DA 20% (FDA) could significantly improve PmO2 and pre-ischaemic haemodilution can delay myocardial ischaemia. We now present an analysis of the pattern of PmO2 changes to be seen when myocardial ischaemia is induced following prior haemodilution with FDA. Two groups of juvenile Yorkshire pigs were anaesthetised with intraperitoneal thiopentone, intubated and ventilated with halothane, nitrous oxide and oxygen. After placement of cardiovascular monitoring lines, a thoracotomy was performed. The pericardium was opened and 4 steel-protected gold microelectrodes were placed in the terminal supply area of the LAD in such a way that 2 electrodes were in the area of myocardial ischaema to be produced. One group of pigs were bled (20 ml/kg) and the loss was replaced with equal volumes of FDA. The animals were ventilated with halothane and oxygen and the terminal LAD was ligated. Electrode outputs were recorded on a flat bed recorder and analysed. LAD occlusion in the control animals resulted in similar changes in PmO2 to those described above.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3364273

  1. Electron attachment and positive ion chemistry of monohydrogenated fluorocarbon radicals

    NASA Astrophysics Data System (ADS)

    Wiens, Justin P.; Shuman, Nicholas S.; Miller, Thomas M.; Viggiano, Albert A.

    2015-08-01

    Rate coefficients and product branching fractions for electron attachment and for reaction with Ar+ are measured over the temperature range 300-585 K for three monohydrogenated fluorocarbon (HFC) radicals (CF3CHF, CHF2CF2, and CF3CHFCF2), as well as their five closed-shell precursors (1-HC2F4I, 2-HC2F4I, 2-HC2F4Br, 1-HC3F6I, 2-HC3F6Br). Attachment to the HFC radicals is always fairly inefficient (between 0.1% and 10% of the Vogt-Wannier capture rate), but generally faster than attachment to analogous perfluorinated carbon radicals. The primary products in all cases are HF-loss to yield CnFm-1- anions, with only a minor branching to F- product. In all cases the temperature dependences are weak. Attachment to the precursor halocarbons is near the capture rate with a slight negative temperature dependence in all cases except for 2-HC2F4Br, which is ˜10% efficient at 300 K and becomes more efficient, approaching the capture rate at higher temperatures. All attachment kinetics are successfully reproduced using a kinetic modeling approach. Reaction of the HFC radicals with Ar+ proceeds at or near the calculated collisional rate coefficient in all cases, yielding a wide variety of product ions.

  2. Investigations of the environmental acceptability of fluorocarbon alternatives to chlorofluorocarbons.

    PubMed Central

    McFarland, M

    1992-01-01

    Chlorofluorocarbons (CFCs) are currently used in systems for preservation of perishable foods and medical supplies, increasing worker productivity and consumer comfort, conserving energy and increasing product reliability. As use of CFCs is phased out due to concerns of ozone depletion, a variety of new chemicals and technologies will be needed to serve these needs. In choosing alternatives, industry must balance concerns over safety and environmental acceptability and still meet the preformance characteristics of the current technology, the only viable alternatives meeting the safety, performance, and environmental requirements for the remaining 40% of demand are fluorocarbons, hydrochlorofluorocarbons (HCFs), and hydrofluorocarbons (HFCs). HCFCs and HFCs possess many of the desirable properties of the CFCs, but because of the, hydrogen, they results in shorter atmospheric lifetimes compared to CFCs and reduces their potential to contribute to stratospheric ozone depletion or global warming; HFCs do not contain chlorine and have no potential to destroy ozone. This paper provides an overview of challenges faced by industry, regulators, and society in general in continuing to meet societal needs and consumer demands while reducing risk to the enviroment without compromising consumer or worker safety. PMID:11607257

  3. Investigations of the environmental acceptability of fluorocarbon alternatives to chlorofluorocarbons.

    PubMed

    McFarland, M

    1992-02-01

    Chlorofluorocarbons (CFCs) are currently used in systems for preservation of perishable foods and medical supplies, increasing worker productivity and consumer comfort, conserving energy and increasing product reliability. As use of CFCs is phased out due to concerns of ozone depletion, a variety of new chemicals and technologies will be needed to serve these needs. In choosing alternatives, industry must balance concerns over safety and environmental acceptability and still meet the preformance characteristics of the current technology, the only viable alternatives meeting the safety, performance, and environmental requirements for the remaining 40% of demand are fluorocarbons, hydrochlorofluorocarbons (HCFs), and hydrofluorocarbons (HFCs). HCFCs and HFCs possess many of the desirable properties of the CFCs, but because of the, hydrogen, they results in shorter atmospheric lifetimes compared to CFCs and reduces their potential to contribute to stratospheric ozone depletion or global warming; HFCs do not contain chlorine and have no potential to destroy ozone. This paper provides an overview of challenges faced by industry, regulators, and society in general in continuing to meet societal needs and consumer demands while reducing risk to the enviroment without compromising consumer or worker safety. PMID:11607257

  4. Plasma surface kinetics studies of etch process in inductively coupled fluorocarbon and hydrogen-containing fluorocarbon plasmas

    NASA Astrophysics Data System (ADS)

    Chang, Won-Seok; Yu, Dong-Hun; Cho, Deog-Gyun; Yook, Yeong-Geun; Chun, Poo-Reum; Lee, Se-Ah; Kwon, Deuk-Chul; Im, Yeon-Ho

    2015-09-01

    Ultra-high deep contact-hole etching is one of the critical issues in fabrication processes of the nanoscale devices. The fluorocarbon (FC) plasmas have been used to obtain the ideal etch profiles. To achieve ultra-high deep contact hole, we present a plasma-surface kinetic studies based on the experimental plasma diagnostic data for silicon dioxide and nitride etch process under inductively coupled FC and HFC plasmas. For this work, the cut-off probe and QMS were used for measuring the electron densities and the ion and neutral radical species. Furthermore, the systematic surface analysis was performed to investigate the thickness and chemical bonding of polymer passivation layer during the etch process. The proposed semi-global surface kinetic model can consider deposition of polymer passivation layer and silicon oxide & nitride etching self-consistently. In this model, thickness of the passivated polymer layer on substrate is calculated from steady-state polymer consumption balance which is composed of sputtered consumption and polymer deposition during oxide etching. Finally, this work will provide better insights to understand basic phenomena of the plasma etching process, leading to the predictable and reliable 3D topography simulation (K-SPEED).

  5. Final report of ''Fundamental Surface Reaction Mechanisms in Fluorocarbon Plasma-Based Processing''

    SciTech Connect

    Gottlieb S. Oehrlein; H. Anderson; J. Cecchi; D. Graves

    2004-09-21

    This report provides a summary of results obtained in research supported by contract ''Fundamental Surface Reaction Mechanisms in Fluorocarbon Plasma-Based Processing'' (Contract No. DE-FG0200ER54608). In this program we advanced significantly the scientific knowledge base on low pressure fluorocarbon plasmas used for patterning of dielectric films and for producing fluorocarbon coatings on substrates. We characterized important neutral and ionic gas phase species that are incident at the substrate, and the processes that occur at relevant surfaces in contact with the plasma. The work was performed through collaboration of research groups at three universities where significantly different, complementary tools for plasma and surface characterization, computer simulation of plasma and surface processes exist. Exchange of diagnostic tools and experimental verification of key results at collaborating institutions, both experimentally and by computer simulations, was an important component of the approach taken in this work.

  6. Control of Fluorocarbon Plasmas for Next-Generation ULSI Devices

    NASA Astrophysics Data System (ADS)

    Tatsumi, Tetsuya

    2008-10-01

    Fluorocarbon (C-F) plasma is widely used in the etching of dielectric materials (SiO2, Si3N4, and SiOCH). Models for controlling C-F plasma [1] and controlling the surface reaction during etching [2] have been proposed. Using these models, good etching results can be obtained after optimizing the absolute densities of reactive species as well as the ion energies. However, next-generation ULSI devices will have smaller pattern sizes, so we need to reduce the pattern-width variation and the degradation thickness of each stacked film to within several nanometers. Even small plasma fluctuations can severely degrade device properties. Furthermore, the densities of reactive species (CFx, O, H, etc.) are sensitive to the surface condition of the chamber wall. The etching properties, therefore, can be shifted by changes in chamber parts, dry cleaning, and/or polymer or metal deposition on chamber walls. To suppress fluctuations in etching performance, we need to understand and completely control the plasma-wall reactions. Using an equipment engineering system (EES) is one way to predict plasma conditions in real time. (An EES is a tool for statistical calculation of etching properties that uses all signals from an etching system, such as flow rate, power, capacitance of matching network, etc.) We analyzed results of plasma-wall reactions and improved the prediction method of etch rate fluctuation using an EES. The simultaneous use of a physical model (supported by in-situ signal monitoring of plasma parameters) and a statistical model is promising for suppressing plasma fluctuation in mass production. [1] T. Tatsumi et al, Jpn. J. Appl. Phys., Part 1 37 (1998) 2394. [2] T. Tatsumi, Applied Surface Science, 253 (2007) 6716.

  7. The environmental history and probable future of Fluorocarbon 11

    SciTech Connect

    Khalil, M.A.K.; Rasmussen, R.A.

    1993-12-01

    The atmospheric concentration of fluorocarbon 11 (F-11) has increased steadily since it was first put into commercial use in the late 1930s and early 1940s. The observed trends, however, have two periods of dramatic declines. The atmospheric trends reflect estimated emissions, which reached highest values in 1974 (340-355 Gg/yr; 1 Gg = 10(exp 9)g) and again in 1988 (314-380 Gg/yr). The observed concentrations and trends agree extremely well with those calculated from independent estimates of emissions from the various sources. Atmospheric concentrations of F-11 are calculated from a mass balance theory involving seven reservoirs and their interactions. Three of the reservoirs are at the Earth`s surface arising from the uses of F-11 (quick-release applications such as open cell foams and aerosols, nonhermetically sealed refrigeration, and rigid polyurethane foams). We estimate that of the 9150 Gg of F-11 that have been produced throughout its history, at present about 1040 Gg are tied up in rigid foams (90 Gg and 24 Gg are tied up refrigeration and quick-release applications, respectively). There are four environmental reservoirs (deep oceans, the ocean mixed layer, the troposphere, and the stratosphere). F-11 is dynamically exchanged between these reservoirs and is destroyed principally by photolysis in the stratosphere and by soils at the Earth`s surface. The future concentrations of F-11 depend on leakage rates from the surface reservoirs and the atmospheric lifetime. It seems that concentrations are not likely to reach the peaks expected earlier and are likely to decline faster than previously thought. This abstract, the figures, and their captions form a self-contained condensed description of our results.

  8. Press Coverage of the Fluorocarbon Controversy: The Rise and Decline of a "Hot" Scientific Issue.

    ERIC Educational Resources Information Center

    Mahaffy, Cheryl

    This paper reviews press coverage of events surrounding the 1977 governmental decision to ban fluorocarbons in spray cans in the United States. The research reported focused on the years 1972 to 1978 and involved a count of the number of items published in selected newspapers and magazines or aired on the three major networks' evening news…

  9. Long Term Aging of Elastomers: Chemorheology of Viton B Fluorocarbon Elastomer

    NASA Technical Reports Server (NTRS)

    Kalfayan, S. H.; Silver, R. H.; Mazzeo, A. A.; Lui, S. T.

    1972-01-01

    The continuation of a study to ascertain the nature, extent, and the rate of chemical changes that take place in certain selected elastomers is reported. Under discussion is Viton B, regarded as a temperature and fuel resistant fluorocarbon rubber. The kinetic analysis of the chemical stress relaxation, and infrared and gel permeation chromatography analysis results are discussed.

  10. Alveolar gas concentrations of fluorocarbons-11 and -12 in man after use of pressurized aerosols

    PubMed Central

    Draffan, G. H.; Dollery, C. T.; Williams, Faith M.; Clare, R. A.

    1974-01-01

    Draffan, G. H., Dollery, C. T., Williams, Faith M., and Clare, R. A. (1974).Thorax, 29, 95-98. Alveolar gas concentrations of fluorocarbons-11 and -12 in man after use of pressurized aerosols. In dogs, inhalation of fluorocarbon aerosol propellants sensitizes the heart to arrhythmias provoked by intravenous injection of adrenaline. In this research, the concentrations of fluorocarbons-11 and -12, CCl3F and CCl2F2, have been measured in alveolar gas in man after using pressurized aerosol inhalers. Fluorocarbons were measured breath by breath using an AEI MS12 mass-spectrometer modified to allow sampling from a respiratory mouthpiece. After a single inhalation from an inhaler by six normal volunteers the mean concentration of fluorocarbon-12 in alveolar gas had reached 5·5 μg/ml, giving a mean apparent volume of distribution of 7·94 litres compared with the mean predicted total lung capacity of 6·61 litres. These results suggest that most of the fluorocarbon expelled from the inhaler entered the alveolar gas. The mean alveolar concentration of F-11 was 2·7 μg/ml and the mean apparent volume of distribution was 12·46 litres. The higher volume of distribution with the less volatile F-11 probably reflects the amount dissolved in lung tissue and pulmonary capillary blood. Similar results were obtained in two patients with obstructive airways disease. One volunteer took an inhalation on every breath up to two minutes and reached an alveolar concentration of F-11 of 29·6 μg/ml and of F-12 of 66·9 μg/ml. The concentration of F-11 required to sensitize the dog heart to arrhythmias was 68 μg/ml. Thus there should be no hazards from the amount entering alveolar gas in normal use after a single inhalation. Inhalation upon every breath over a period raises the alveolar concentration to one approaching that which, in the dog, might be hazardous. PMID:4825557

  11. Application of Chemically Adsorbed Fluorocarbon Film with Highly Durability as a Mold Release Agent

    NASA Astrophysics Data System (ADS)

    Yamamoto, Hiroyuki; Ohkubo, Yuji; Ogawa, Kazufumi; Utsumi, Kunihiro

    In this study, the physical performance (adhesion resistance, heat resistance, abrasion resistance, chemical resistance) extremely thin, highly durable and chemically adsorbed fluorocarbon film with low surface energy on the metal surface (the thickness is about 1 nm order.) was evaluated, and the evaluation results (durability, demolding resistance) on the actual injection molding performance up to 100,000 shots using a test mold were reported. The demolding resistance could be drastically decreased without losing the mold shape and dimensional accuracy by using the chemically adsorbed and highly durable fluorocarbon film. From these results, this technique should be useful for molding various elastomers such as silicone and urethane resin which are difficult to release from a mold for making high precision products such as optical components and chemical chips.

  12. Nano-ring-shape growth of fluorocarbon macromolecules during SiO2 etching.

    PubMed

    Lee, Sang Hwui; Lu, Jian-Qiang

    2010-04-16

    A unique nanoscale ring-shape pattern of fluorocarbon macromolecules grown during SiO2 reactive ion etching (RIE) is presented. This pattern was discovered after SiO2 RIE using trifluoromethane (CHF3) and oxygen. Typical dimensions of the ring-type fluorocarbon structure are found to be approximately 50 nm in diameter, approximately 10 nm in wall thickness, and approximately 50 nm in height in this study. The ring-shape structure grows towards a tube-shape structure up to 500 nm. Morphological studies are also presented with various plasma etching parameters. This experiment shows that oxygen-rich RIE etching produces more ring-type structures. This could be used as a nanoscale template for other applications. PMID:20332556

  13. Nano-ring-shape growth of fluorocarbon macromolecules during SiO2 etching

    NASA Astrophysics Data System (ADS)

    Hwui Lee, Sang; Lu, Jian-Qiang

    2010-04-01

    A unique nanoscale ring-shape pattern of fluorocarbon macromolecules grown during SiO2 reactive ion etching (RIE) is presented. This pattern was discovered after SiO2 RIE using trifluoromethane (CHF3) and oxygen. Typical dimensions of the ring-type fluorocarbon structure are found to be ~ 50 nm in diameter, ~ 10 nm in wall thickness, and ~ 50 nm in height in this study. The ring-shape structure grows towards a tube-shape structure up to 500 nm. Morphological studies are also presented with various plasma etching parameters. This experiment shows that oxygen-rich RIE etching produces more ring-type structures. This could be used as a nanoscale template for other applications.

  14. Absorption and recovery of n-hexane in aqueous solutions of fluorocarbon surfactants.

    PubMed

    Xiao, Xiao; Yan, Bo; Fu, Jiamo; Xiao, Xianming

    2015-11-01

    n-Hexane is widely used in industrial production as an organic solvent. As an industrial exhaust gas, the contribution of n-hexane to air pollution and damage to human health are attracting increasing attention. In the present study, aqueous solutions of two fluorocarbon surfactants (FSN100 and FSO100) were investigated for their properties of solubilization and dynamic absorption of n-hexane, as well as their capacity for regeneration and n-hexane recovery by thermal distillation. The results show that the two fluorocarbon surfactants enhance dissolution and absorption of n-hexane, and their effectiveness is closely related to their concentrations in solution. For low concentration solutions (0.01%-0.30%), the partition coefficient decreases dramatically and the saturation capacity increases significantly with increasing concentration, but the changes for both are more modest when the concentration is over 0.30%. The FSO100 solution presents a smaller partition coefficient and a greater saturation capacity than the FSN100 solution at the same concentration, indicating a stronger solubilization for n-hexane. Thermal distillation is a feasible method to recover n-hexane from these absorption solutions, and to regenerate them. With 90sec heating at 80-85°C, the recovery of n-hexane ranges between 81% and 85%, and the regenerated absorption solution maintains its original performance during reuse. This study provides basic information on two fluorocarbon surfactants for application in the treatment of industrial n-hexane waste gases. PMID:26574100

  15. The corrosion phenomena in the coin cell BR2325 of the ``superstoichiometric fluorocarbon-lithium'' system

    SciTech Connect

    Mitkin, V.N.; Galkin, P.S.; Denisova, T.N.

    1998-07-01

    It was noted at the earlier study and at the longer observations of the novel various types of superstoichiometric fluorocarbon materials CF{sub 1+x}, where x = 0.1--0.33 (FCM) and their behavior, that despite of their known hygroscopity during a storage of samples in laboratory and technological utensils nevertheless occurs an appreciable sorption of atmospheric moisture. The color of samples does not change but sometimes there appears a smell of hydrogen fluoride and even corrosion of glasswares at a long storage. On the basis of these facts was assumed that at a long storage the slow reactions of HF producing with a sorption moisture can proceed. This phenomena is necessary to take into account for successful manufacturing of long life lithium cells based on superstoichiometric fluorocarbon composite cathodes (FCC). The chemistry of such slow hydrolytic process and especially of processes which can proceed at manufacturing of FCC earlier was not investigated also of any data in the literature in this occasion is not present. Just for this reason the authors undertook a study of the corrosion phenomena which can proceed in industrial sources of a current at a long storage under influence of slow hydrolysis of C-F bonds by moisture. The goal of the study was to search long term damages in the slightly wet FCM and based on these materials cathodic composites for fluorocarbon-lithium cells. As a model for corrosion process investigation they have chosen a standard coin lithium battery of a type BR2325.

  16. Histamine release associated with intravenous delivery of a fluorocarbon-based sevoflurane emulsion in canines.

    PubMed

    Johnson, Rebecca A; Simmons, Ken T; Fast, Jonathan P; Schroeder, Carrie A; Pearce, Robert A; Albrecht, Ralph M; Mecozzi, Sandro

    2011-07-01

    The purpose of this study was to evaluate the effectiveness of a novel fluorocarbon-based sevoflurane emulsion in dogs previously shown to produce short-term rodent anesthesia. On the basis of an unexpected allergic-type clinical reaction, we also tested the hypothesis that this type of formulation causes histamine release and complement activation. Physiological parameters, plasma histamine levels (radioimmunoassay), and complement activation (enzyme immunoassay) were quantified in response to emulsion components, including F13M5 (the emulsion's fluorocarbon-based polymer) and methoxy poly(ethylene glycol) 5000 (the polymer's hydrophilic block). Although the emulsion produced general anesthesia in dogs, they also experienced hypotension and clinical signs suggestive of an allergic-like response (i.e., vasodilation, urticaria, and pruritus upon recovery). Emulsions lacking sevoflurane failed to induce anesthesia but did elicit the allergic response. Plasma histamine levels were significantly increased following injection of micellar solutions of F13M5. Direct complement activation by the emulsion or its components was weak or absent. An allergic response leading to histamine release, likely initiated by the F13M5 component via an immunoglobulin pathway, is associated with an intravenous fluorocarbon-based emulsion of sevoflurane. Subsequently, its usefulness in medicine in its present formulation is limited. PMID:21246564

  17. Structure and Depletion at Fluorocarbon and Hydrocarbon/Water Liquid/Liquid Interfaces

    SciTech Connect

    Kashimoto,K.; Yoon, J.; Hou, B.; Chen, C.; Lin, B.; Aratono, M.; Takiue, T.; Schlossman, M.

    2008-01-01

    The results of x-ray reflectivity studies of two oil/water (liquid/liquid) interfaces are inconsistent with recent predictions of the presence of a vaporlike depletion region at hydrophobic/aqueous interfaces. One of the oils, perfluorohexane, is a fluorocarbon whose superhydrophobic interface with water provides a stringent test for the presence of a depletion layer. The other oil, heptane, is a hydrocarbon and, therefore, is more relevant to the study of biomolecular hydrophobicity. These results are consistent with the subangstrom proximity of water to soft hydrophobic materials.

  18. Synthesis and self-assembly of fluorocarbon- and hydrocarbon-modified hydrophilic polymers. Final report

    SciTech Connect

    Hogen-Esch, T.E.

    1996-11-01

    Over the past 3 years, work was done in several areas: effect of spacer lengths on degree of association of hydrophobically modified polyacrylamides; fluorocarbon mediated association of R{sub F}- substituted polyacrylamide-2-(acrylamido)-2-methyl-propane sodium sulfonate copolymers; hydrophobic association in R{sub F}(R{sub H})-modified poly(N,N-dimethylacrylamide)(PDMA) and polyvinylpyrrolidone; synthesis of R{sub F}-containing poly(N- isopropyl acrylamide)`s; synthesis of HM narrow MWD telechelics PDMA and PDMA block copolymers; and studies of telechelic R{sub F}(R{sub H}) derivatives of polyethyleneglycols. 15 refs, 7 figs, 2 tabs.

  19. Properties of solid polymer electrolyte fluorocarbon film. [used in hydrogen/oxygen fuel cells

    NASA Technical Reports Server (NTRS)

    Alston, W. B.

    1973-01-01

    The ionic fluorocarbon film used as the solid polymer electrolyte in hydrogen/oxygen fuel cells was found to exhibit delamination failures. Polarized light microscopy of as-received film showed a lined region at the center of the film thickness. It is shown that these lines were not caused by incomplete saponification but probably resulted from the film extrusion process. The film lines could be removed by an annealing process. Chemical, physical, and tensile tests showed that annealing improved or sustained the water contents, spectral properties, thermo-oxidative stability, and tensile properties of the film. The resistivity of the film was significantly decreased by the annealing process.

  20. Mesoporous Fluorinated Metal-Organic Frameworks with Exceptional Adsorption of Fluorocarbons and CFCs.

    PubMed

    Chen, Teng-Hao; Popov, Ilya; Kaveevivitchai, Watchareeya; Chuang, Yu-Chun; Chen, Yu-Sheng; Jacobson, Allan J; Miljanić, Ognjen Š

    2015-11-16

    Two mesoporous fluorinated metal-organic frameworks (MOFs) were synthesized from extensively fluorinated tritopic carboxylate- and tetrazolate-based ligands. The tetrazolate-based framework MOFF-5 has an accessible surface area of 2445 m(2) g(-1), the highest among fluorinated MOFs. Crystals of MOFF-5 adsorb hydrocarbons, fluorocarbons, and chlorofluorocarbons (CFCs)-the latter two being ozone-depleting substances and potent greenhouse species-with weight capacities of up to 225%. The material exhibits an apparent preference for the adsorption of non-spherical molecules, binding unusually low amounts of both tetrafluoromethane and sulfur hexafluoride. PMID:26423312

  1. Real-Time Trace Gas Sensing of Fluorocarbons using a Swept-wavelength External Cavity Quantum Cascade Laser

    SciTech Connect

    Phillips, Mark C.; Taubman, Matthew S.; Bernacki, Bruce E.; Cannon, Bret D.; Stahl, Robert D.; Schiffern, John T.; Myers, Tanya L.

    2014-05-04

    We present results demonstrating real-time sensing of four different fluorocarbons at low-ppb concentrations using an external cavity quantum cascade laser (ECQCL) operating in a swept-wavelength configuration. The ECQCL was repeatedly swept over its full tuning range at a 20 Hz rate with a scan rate of 3535 cm-1/s, and a detailed characterization of the ECQCL scan stability and repeatability is presented. The sensor was deployed on a mobile automotive platform to provide spatially resolved detection of fluorocarbons in outdoor experiments. Noise-equivalent detection limits of 800-1000 parts-per-trillion (ppt) are demonstrated for 1 s integration times.

  2. Gas Adsorption Properties of Fluorocarbon Thin Films Prepared Using Three Different Types of RF Magnetron Sputtering Systems

    NASA Astrophysics Data System (ADS)

    Satoru Iwamori,; Norihiko Hasegawa,; Satoshi Yano,; Kazutoshi Noda,

    2010-04-01

    Fluorocarbon thin films were deposited onto a quartz crystal with a poly(tetrafluoroethylene) target using three different types of RF magnetron sputtering systems with strong, weak, and unbalanced magnetic fields. The adsorption properties of these thin films for water, ethanol, acetone, acetaldehyde, toluene, and methyl salicylate were evaluated using the quartz crystal microbalance (QCM) method in order to characterize the surface properties of these thin films. These thin films have low sensitivities to non-polar solvents that contain methyl and aromatic groups, and high sensitivities to polar solvents that contain carbonyl and hydroxyl groups. Chemical structures, especially, polar moieties in these fluorocarbon thin films would affect the gas adsorption properties.

  3. Effect of fluorocarbon-for-blood exchange on regional blood flow in rats

    SciTech Connect

    Lee, P.A.; Sylvia, A.L.; Piantadosi, C.A. )

    1988-04-01

    Cerebrocirculatory responses to total perfluorocarbon (FC-43)-for-blood replacement were studied in anesthetized, ventilated rats breathing 100% O{sub 2}. Changes in total and regional cerebral blood flow (CBF) were measured using the radiolabeled-microsphere technique. The data were compared with two control groups of hemoglobin-circulated animals; one group was exposed to arterial hypoxia and the other to isovolemic hemodilution with Krebs-Henseleit-albumin (KHA) solution. Exchange transfusion with FC-43 doubled total and regional CBF, causing preferential flow increases to the cortex and cerebellum. Estimated cerebrovascular resistance fell to 50% of the preexchange value. Both hemodilution and hypoxia control experiments produced CBF responses similar to those obtained in FC-43 animals. Although calculated arterial O{sub 2} contents in all three groups of animals were similar, blood viscosity was normal in hypoxic rats and reduced in KHA and FC-43 animals. Since arterial and cerebrovenous Po{sub 2}s were both high in fluorocarbon-circulated rats, over results suggest that decreased O{sub 2} content and perhaps lower viscosity of the circulating fluorocarbon were responsible for increases in CBF required to maintain sufficient delivery of O{sub 2} to the brain.

  4. Synthesis, Thermal Properties and Cytotoxicity Evaluation of Hydrocarbon and Fluorocarbon Alkyl β-D-xylopyranoside Surfactants

    PubMed Central

    Xu, Wenjin; Osei-Prempeh, Gifty; Lema Herrera, Fresia C.; Oldham, E. Davis; Aguilera, Renato J.; Parkin, Sean; Rankin, Stephen E.; Knutson, Barbara L.; Lehmler, Hans-Joachim

    2011-01-01

    Alkyl β-D-xylopyranosides are highly surface active, biodegradable surfactants that can be prepared from hemicelluloses and are of interest for use as pharmaceuticals, detergents, agrochemicals and personal care products. To gain further insights into their structure-property and structure-activity relationships, the present study synthesized a series of hydrocarbon (-C6H13 to -C16H33) and fluorocarbon (-(CH2)2C6F13) alkyl β-D-xylopyranosides in four steps from D-xylose by acylation or benzoylation, bromination, Koenigs-Knorr reaction and hydrolysis, with the benzoyl protecting group giving better yields compared to the acyl group in the Koenigs-Knorr reaction. All alkyl β-D-xylopyranosides formed thermotropic liquid crystals. The phase transition of the solid crystalline phase to a liquid crystalline phase increased linearly with the length of the hydrophobic tail. The clearing points were near constant for alkyl β-D-xylopyranosides with a hydrophobic tail ≥ 8, but occurred at a significantly lower temperature for hexyl β-D-xylopyranoside. Short and long-chain alkyl β-D-xylopyranosides displayed no cytotoxicity at concentration below their aqueous solubility limit. Hydrocarbon and fluorocarbon alkyl β-D-xylopyranosides with intermediate chain length displayed some toxicity at millimolar concentrations due to apoptosis. PMID:22207000

  5. Single-Step Fluorocarbon Plasma Treatment-Induced Wrinkle Structure for High-Performance Triboelectric Nanogenerator.

    PubMed

    Cheng, Xiaoliang; Meng, Bo; Chen, Xuexian; Han, Mengdi; Chen, Haotian; Su, Zongming; Shi, Mayue; Zhang, Haixia

    2016-01-01

    A triboelectric nanogenerator (TENG) has been thought to be a promising method to harvest energy from environment. To date, the utilization of surface structure and material modification has been considered the most effective way to increase its performance. In this work, a wrinkle structure based high-performance TENG is presented. Using the fluorocarbon plasma treatment method, material modification and surface structure are introduced in one step. The output ability of TENG is dramatically enhanced. After the optimization of plasma treatment, the maximum current and surface charge density are 182 μA about 165 μC m(-2) . Compared with untreated TENG, the wrinkle structure makes the current and surface charge density increase by 810% and 528%, separately. X-ray photoelectron spectroscopy is employed to analyze the chemical modification mechanism of this fluorocarbon plasma treatment. Facilitated by its high output performance, this device could directly light 76 blue light emitting diodes under finger typing. The output electric energy could be stored then utilized to power a commercial calculator. As a result of the simple fabrication process and high output ability, devices fabricated using this method could bring forward practical applications using TENGs as power sources. PMID:26619271

  6. Fluorocarbon and hydrocarbon N-heterocyclic (C5-C7) imidazole-based liquid crystals.

    PubMed

    Chen, Hongren; Hong, Fengying; Shao, Guang; Hang, Deyu; Zhao, Lei; Zeng, Zhuo

    2014-12-01

    By using three synthetic protocols, a series of fluorocarbon and hydrocarbon N-heterocyclic imidazole-based liquid crystals (LCs) and related imidazolium-based ionic liquid crystals (ILCs) have been prepared. The ring size of the N-heterocycle and the length of the N-terminal chain (on the imidazolium unit in the ILCs) were modified, and the influence of these structural parameters on liquid-crystal phases was investigated by means of polarizing optical microscopy (POM), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). These new ILCs exhibit a disordered smectic phase (SmA), good thermal stabilities, a broad smectic phase range, a high dipole moment, relatively low melting points, but high clearing points and strong emission fluorescence relative to imidazole-based LCs. These encouraging results have led us to believe these fluorocarbon and hydrocarbon N-heterocyclic imidazole-based LCs and related imidazolium-based ILCs could be used as new liquid-crystalline materials. PMID:25256069

  7. Chemical modification of the poly(vinylidene fluoride-trifluoroethylene) copolymer surface through fluorocarbon ion beam deposition

    SciTech Connect

    Hsu, W.-D.; Jang, Inkook; Sinnott, Susan B.

    2007-07-15

    Classical molecular dynamics simulations are used to study the effects of continuous fluorocarbon ion beam deposition on a poly(vinylidene fluoride-trifluoroethylene) [P(VDF-trFE)] surface, a polymer with electromechanical properties. Fluorocarbon plasma processing is widely used to chemically modify surfaces and deposit thin films. It is well accepted that polyatomic ions and neutrals within low-energy plasmas have a significant effect on the surface chemistry induced by the plasma. The deposition of mass selected fluorocarbon ions is useful to isolate the effects specific to polyatomic ions. Here, the differences in the chemical interactions of C{sub 3}F{sub 5}{sup +} and CF{sub 3}{sup +} ions with the P(VDF-trFE) surface are examined. The incident energy of the ions in both beams is 50 eV. The CF{sub 3}{sup +} ions are predicted to be more effective at fluorinating the P(VDF-trFE) surface than C{sub 3}F{sub 5}{sup +} ions. At the same time, the C{sub 3}F{sub 5}{sup +} ions are predicted to be more effective at growing fluorocarbon thin films. The simulations also reveal how the deposition process might ultimately modify the electromechanical properties of this polymer surface.

  8. CF2 kinetics and related mechanisms in the presence of polymers in fluorocarbon plasmas

    NASA Astrophysics Data System (ADS)

    Tserepi, A. D.; Derouard, J.; Booth, J. P.; Sadeghi, N.

    1997-03-01

    Laser-induced fluorescence was used to characterize the fluorocarbon plasma that was used to modify the wettability of hexatriacontane (HTC), a polymer model. The plasma volume downstream from a microwave plasma source was examined by monitoring the CF2 concentration as well as the CF2 decay rate (in the afterglow of a pulsed discharge) during treatment of the polymer surface (in 20-100 mTorr CF4). In parallel, the behavior of F atoms was monitored by means of actinometric optical emission. Pulsed modulation of the discharge allowed the effects of variations in the loss and production rates for CF2 to be distinguished, in the presence of hexatriacontane. Our observations are consistent with enhanced production of CF2, possibly by an ion-assisted surface mechanism, in the presence of HTC.

  9. Assessment of effects on vegetation of degradation products from alternative fluorocarbons

    NASA Technical Reports Server (NTRS)

    Mccune, D. C.; Weinstein, L. H.

    1990-01-01

    Concern with the effects of fluorides on plants has been devoted to that resulting from dry deposition (mainly with reference to gaseous HF and secondarily with particulate forms). The occurrence of precipitation as rain or mist and the presence of dew or free water on the foliage has mainly been considered with respect to their effects on the accumulation of air-borne fluoride and not with fluoride in wet deposition. That is, precipitation has been viewed primarily with respect to its facilitation of the solution and subsequent absorption of deposits by the foliar tissues or its elution of deposited fluoride from foliage. Accordingly, our evaluation of inorganic fluoride from fluorocarbon degradation rests upon a comparison with what is known about the effects of industrial emissions and what could be considered the natural condition.

  10. Review of ultraviolet absorption cross sections of a series of alternative fluorocarbons

    NASA Technical Reports Server (NTRS)

    Molina, Mario J.

    1990-01-01

    Solar photolysis is likely to contribute to the stratospheric destruction of those alternative fluorocarbons (HFC's) which have two or more chlorine atoms bonded to the same carbon atom. Two of the eight HFC's considered here fall into this category, namely HFC-123 and HFC141b. For these two species there is good agreement among the various measurements of the ultraviolet cross sections in the wavelength region which is important for atmospheric photodissociation, that is, around 200 nm. There is also good agreement for HFC-124, HFC-22 and HFC-142b. These are the three species which contain one chlorine atom per molecule. The agreement in the measurements is poor for the other species, i.e., those that do not contain chlorine, except in so far as to corroborate that solar photolysis should be negligible relative to destruction by hydroxyl radicals.

  11. Molecular composition of films and solid particles polymerized in fluorocarbon plasmas

    NASA Astrophysics Data System (ADS)

    Takahashi, Kazuo; Tachibana, Kunihide

    2001-01-01

    In fluorocarbon (C4F8) plasmas, formation mechanisms of polymers were investigated by the characterization with x-ray photoelectron spectroscopy (XPS) and gel permeation chromatography (GPC). The molecular compositions of the polymers in the films deposited on the substrate and in the particles formed in the gas phase were elucidated by these chemical analyses. The XPS results showed that the particles were carbon-rich and composed of highly branched molecules in contrast to the film composition. From the GPC measurements, the particles were found to contain ultrahigh mass polymers, whose molecular weights were around 100 000. On the contrary, the deposited film contained polymers with molecular weights distributed below 2000, in which oligomers, monomers, and fragmented products were included. Present study suggests that these polymers are involved in the formation of crosslinked networks of the films and the particles via surface reactions, where the crosslinking is enhanced by the ion bombardment.

  12. Fluorocarbon-23 measure of cat cerebral blood flow by nuclear magnetic resonance

    SciTech Connect

    Ewing, J.R.; Branch, C.A.; Fagan, S.C.; Helpern, J.A.; Simkins, R.T.; Butt, S.M.; Welch, K.M. )

    1990-01-01

    We employed fluorocarbon-23 (trifluoromethane) as a nuclear magnetic resonance gaseous indicator of cerebral blood flow in seven cats. Pulsed inhalation of this indicator and switching between two coils allowed the acquisition of both an arterial input and a cerebral response function, making possible multicompartmental curve fits to cerebral uptake and clearance data. The brain:blood partition coefficient for trifluoromethane was 0.9 for both gray and white matter. Fast-compartment blood flows were normal and showed appropriate CO{sub 2} reactivity. Slow-compartment blood flows did not demonstrate CO{sub 2} reactivity, probably because cranial as well as white-matter blood flows were lumped together in the slow compartment. Although cerebral blood flow was stable during administration of 60% trifluoromethane, the compound did prove to be a mild cardiac sensitizer to epinephrine in five cats.

  13. A Microfluidic Cell Co-Culture Platform with a Liquid Fluorocarbon Separator

    PubMed Central

    Brewer, Bryson M.; Shi, Mingjian; Edd, Jon F.; Webb, Donna J.; Li, Deyu

    2014-01-01

    A microfluidic cell co-culture platform that uses a liquid fluorocarbon oil barrier to separate cells into different culture chambers has been developed. Characterization indicates that the oil barrier could be effective for multiple days, and a maximum pressure difference between the oil barrier and aqueous media in the cell culture chamber could be as large as ∼3.43 kPa before the oil barrier fails. Biological applications have been demonstrated with the separate transfection of two groups of primary hippocampal neurons with two different fluorescent proteins and subsequent observation of synaptic contacts between the neurons. In addition, the quality of the fluidic seal provided by the oil barrier is shown to be greater than that of an alternative solid-PDMS valve barrier design by testing the ability of each device to block low molecular weight CellTracker dyes used to stain cells in the culture chambers. PMID:24420386

  14. Overcoming inactivation of the lung surfactant by serum proteins: a potential role for fluorocarbons?

    PubMed

    Krafft, Marie Pierre

    2015-08-14

    In many pulmonary conditions serum proteins interfere with the normal adsorption of components of the lung surfactant to the surface of the alveoli, resulting in lung surfactant inactivation, with potentially serious untoward consequences. Here, we review the strategies that have recently been designed in order to counteract the biophysical mechanisms of inactivation of the surfactant. One approach includes protein analogues or peptides that mimic the native proteins responsible for innate resistance to inactivation. Another perspective uses water-soluble additives, such as electrolytes and hydrophilic polymers that are prone to enhance adsorption of phospholipids. An alternative, more recent approach consists of using fluorocarbons, that is, highly hydrophobic inert compounds that were investigated for partial liquid ventilation, that modify interfacial properties and can act as carriers of exogenous lung surfactant. The latter approach that allows fluidisation of phospholipid monolayers while maintaining capacity to reach near-zero surface tension definitely warrants further investigation. PMID:26110877

  15. A microfluidic cell co-culture platform with a liquid fluorocarbon separator.

    PubMed

    Brewer, Bryson M; Shi, Mingjian; Edd, Jon F; Webb, Donna J; Li, Deyu

    2014-04-01

    A microfluidic cell co-culture platform that uses a liquid fluorocarbon oil barrier to separate cells into different culture chambers has been developed. Characterization indicates that the oil barrier could be effective for multiple days, and a maximum pressure difference between the oil barrier and aqueous media in the cell culture chamber could be as large as ~3.43 kPa before the oil barrier fails. Biological applications have been demonstrated with the separate transfection of two groups of primary hippocampal neurons with two different fluorescent proteins and subsequent observation of synaptic contacts between the neurons. In addition, the quality of the fluidic seal provided by the oil barrier is shown to be greater than that of an alternative solid-PDMS valve barrier design by testing the ability of each device to block low molecular weight CellTracker dyes used to stain cells in the culture chambers. PMID:24420386

  16. Assembly and Structure of alpha-helical Peptide Films on Hydrophobic Fluorocarbon Surfaces

    SciTech Connect

    Weidner, T.; Samual, N; McCrea, K; Gamble, L; Ward, R; Castner, D

    2010-01-01

    The structure, orientation, and formation of amphiphilic {alpha}-helix model peptide films on fluorocarbon surfaces has been monitored with sum frequency generation (SFG) vibrational spectroscopy, near-edge x-ray absorption fine structure (NEXAFS) spectroscopy, and x-ray photoelectron spectroscopy (XPS). The {alpha}-helix peptide is a 14-mer of hydrophilic lysine and hydrophobic leucine residues with a hydrophobic periodicity of 3.5. This periodicity yields a rigid amphiphilic peptide with leucine and lysine side chains located on opposite sides. XPS composition analysis confirms the formation of a peptide film that covers about 75% of the surface. NEXAFS data are consistent with chemically intact adsorption of the peptides. A weak linear dichroism of the amide {pi}* is likely due to the broad distribution of amide bond orientations inherent to the {alpha}-helical secondary structure. SFG spectra exhibit strong peaks near 2865 and 2935 cm{sup -1} related to aligned leucine side chains interacting with the hydrophobic surface. Water modes near 3200 and 3400 cm{sup -1} indicate ordering of water molecules in the adsorbed-peptide fluorocarbon surface interfacial region. Amide I peaks observed near 1655 cm{sup -1} confirm that the secondary structure is preserved in the adsorbed peptide. A kinetic study of the film formation process using XPS and SFG showed rapid adsorption of the peptides followed by a longer assembly process. Peptide SFG spectra taken at the air-buffer interface showed features related to well-ordered peptide films. Moving samples through the buffer surface led to the transfer of ordered peptide films onto the substrates.

  17. Study of the adhesion of thin plasma fluorocarbon coatings resisting plastic deformation for stent applications

    NASA Astrophysics Data System (ADS)

    Lewis, F.; Horny, P.; Hale, P.; Turgeon, S.; Tatoulian, M.; Mantovani, D.

    2008-02-01

    Metallic intravascular stents are medical devices (316L stainless steel) used to support the narrowed lumen of atherosclerotic stenosed arteries. Despite the success of bare metal stents, restenosis remains the main complication after 3-6 months of implantation. To reduce the restenosis rate of bare metal stents, stent coating is an interesting alternative. Firstly, it allows the modification of the surface properties, which is in contact with the biological environment. Secondly, the coating could eventually act as a carrier for drug immobilization and release. Moreover, the in vivo stent implantation requires in situ stent expansion. This mandatory step generates local plastic deformation of up to 25% and may cause coating failures such as cracking and delamination. Fluorocarbon films were selected in this study as a potential stent coating, mainly due to their chemical inertness, high hydrophobicity, protein retention capabilities and thromboresistance properties. The aim of this study was to investigate the adhesion properties of fluorocarbon films of three different thicknesses deposited by plasma polymerization in C2F6/H2 on 316L stainless steel substrates. A previously developed small punch test was used to deform the coated samples. According to atomic force microscopy, field emission scanning electron microscopy and x-ray photoelectron spectroscopy characterizations, among the coatings with different thicknesses studied, only those with a thickness of 36 nm exhibited the required cohesion and interfacial adhesion to resist the stent expansion without cracking or delaminating. Otherwise, cracks were detected in the coatings having thicknesses equal or superior to 100 nm, indicating a lack of cohesion.

  18. A nanoscale fluorocarbon coating on PET surfaces improves the adhesion and growth of cultured coronary endothelial cells

    NASA Astrophysics Data System (ADS)

    Pezzatini, S.; Morbidelli, L.; Gristina, R.; Favia, P.; Ziche, M.

    2008-07-01

    Plasma deposition was applied to deposit smooth and nanostructured fluorocarbon coatings on polyethylene terephthalate substrates, with the aim to obtain surfaces with identical chemical composition but different roughness to improve the endothelialization process on PET surfaces. We found that increased roughness was associated with enhanced endothelial cell response, as shown by the ability of cells to grow and adhere to nanostructures. We also observed specific interaction of filopodia protruding from the cell membrane with individual nanostructures, leading to increased cell attachment, spreading and cell viability. Among the modified surfaces, one termed PET-tfl90 emerged as the one capable of best sustaining the formation of a confluent monolayer of endothelial cells. In conclusion, PET modified by nanostructured fluorocarbon film represents an improved graft material, over conventional PET, for endothelial cell adhesion and growth.

  19. Real-time trace gas sensing of fluorocarbons using a swept-wavelength external cavity quantum cascade laser.

    PubMed

    Phillips, Mark C; Taubman, Matthew S; Bernacki, Bruce E; Cannon, Bret D; Stahl, Robert D; Schiffern, John T; Myers, Tanya L

    2014-05-01

    We present results demonstrating real-time sensing of four different fluorocarbons at low part-per billion (ppb) concentrations using an external cavity quantum cascade laser (ECQCL) designed for infrared vibrational spectroscopy of molecules with broad absorption features. The ECQCL was repeatedly swept at 20 Hz over its full tuning range of 1145-1265 cm(-1) providing a scan rate of 3535 cm(-1) s(-1), and a detailed characterization of the ECQCL scan stability and repeatability is presented. The ECQCL was combined with a 100 meter path length multi-pass cell for direct absorption spectroscopy. A portable sensor system is described, which was deployed on a mobile automotive platform to provide spatially-resolved detection of fluorocarbons in outdoor experiments. Noise-equivalent detection limits of 800-1000 parts-per-trillion (ppt) are demonstrated for 1 s integration times. PMID:24384671

  20. Biofabrication Under Fluorocarbon: A Novel Freeform Fabrication Technique to Generate High Aspect Ratio Tissue-Engineered Constructs

    PubMed Central

    Blaeser, Andreas; Duarte Campos, Daniela F.; Weber, Michael; Neuss, Sabine; Theek, Benjamin; Fischer, Horst

    2013-01-01

    Abstract Bioprinting is a recent development in tissue engineering, which applies rapid prototyping techniques to generate complex living tissues. Typically, cell-containing hydrogels are dispensed layer-by-layer according to a computer-generated three-dimensional model. The lack of mechanical stability of printed hydrogels hinders the fabrication of high aspect ratio constructs. Here we present submerged bioprinting, a novel technique for freeform fabrication of hydrogels in liquid fluorocarbon. The high buoyant density of fluorocarbons supports soft hydrogels by floating. Hydrogel constructs of up to 30-mm height were generated. Using 3% (w/v) agarose as the hydrogel and disposable syringe needles as nozzles, the printer produced features down to 570-μm diameter with a lateral dispensing accuracy of 89 μm. We printed thin-walled hydrogel cylinders measuring 4.8 mm in height, with an inner diameter of ∼2.9 mm and a minimal wall thickness of ∼650 μm. The technique was successfully applied in printing a model of an arterial bifurcation. We extruded under fluorocarbon, cellularized alginate tubes with 5-mm outer diameter and 3-cm length. Cells grew vigorously and formed clonal colonies within the 7-day culture period. Submerged bioprinting thus seems particularly suited to fabricate hollow structures with a high aspect ratio like vascular grafts for cardiovascular tissue engineering as well as branching or cantilever-like structures, obviating the need for a solid support beneath the overhanging protrusions. PMID:24083093

  1. Biofabrication under fluorocarbon: a novel freeform fabrication technique to generate high aspect ratio tissue-engineered constructs.

    PubMed

    Blaeser, Andreas; Duarte Campos, Daniela F; Weber, Michael; Neuss, Sabine; Theek, Benjamin; Fischer, Horst; Jahnen-Dechent, Willi

    2013-10-01

    Bioprinting is a recent development in tissue engineering, which applies rapid prototyping techniques to generate complex living tissues. Typically, cell-containing hydrogels are dispensed layer-by-layer according to a computer-generated three-dimensional model. The lack of mechanical stability of printed hydrogels hinders the fabrication of high aspect ratio constructs. Here we present submerged bioprinting, a novel technique for freeform fabrication of hydrogels in liquid fluorocarbon. The high buoyant density of fluorocarbons supports soft hydrogels by floating. Hydrogel constructs of up to 30-mm height were generated. Using 3% (w/v) agarose as the hydrogel and disposable syringe needles as nozzles, the printer produced features down to 570-?m diameter with a lateral dispensing accuracy of 89??m. We printed thin-walled hydrogel cylinders measuring 4.8?mm in height, with an inner diameter of ?2.9?mm and a minimal wall thickness of ?650??m. The technique was successfully applied in printing a model of an arterial bifurcation. We extruded under fluorocarbon, cellularized alginate tubes with 5-mm outer diameter and 3-cm length. Cells grew vigorously and formed clonal colonies within the 7-day culture period. Submerged bioprinting thus seems particularly suited to fabricate hollow structures with a high aspect ratio like vascular grafts for cardiovascular tissue engineering as well as branching or cantilever-like structures, obviating the need for a solid support beneath the overhanging protrusions. PMID:24083093

  2. Influence of Fluorocarbon Polymer Film Deposited on Aluminum Electrodes on Breakdown Voltage of Nitrogen

    NASA Astrophysics Data System (ADS)

    Biloiu, C.; Biloiu, I. A.; Sakai, Y.; Sugawara, H.; Suda, Y.; Nakajima, M.

    2001-10-01

    In the present work, fluorocarbon polymer films (FCP) were fabricated on Al electrodes by plasma enhanced chemical vapor deposition (PECVD), and the influence of these films on the breakdown voltage of nitrogen gas were examined. The electrodes were made of aluminum with sphere shape of 40 mm diameter. FCP films with a thickness from a few tens of nm up to a few μm have been obtained in 13.56 MHz C_8F_18 vapor plasma. The XPS analysis of the films showed the successful formation of FCP due to the presence of the characteristic chemical bonds components: C--C at 285 eV, C--CFx at 287.3 eV, CF at 289.5 eV, CF2 at 292.1 eV, and CF3 at 294 eV. The breakdown voltage was measured in nitrogen gas in the pressure range between 0.2 and 10 Torr, for gap lengths between 1 and 2 cm. The result revealed that the breakdown voltage increased approximately 365 V for a case of FCP film thickness of 10 μm.

  3. Global warming impacts of CFC alternative technologies: Combining fluorocarbon and CO{sub 2} effects

    SciTech Connect

    Fairchild, P.D.; Fischer, S.K.; Hughes, P.J.

    1992-12-31

    Chlorofluorocarbons (CFCs) are on their way out, due to their role in stratospheric ozone depletion and the related international Montreal Protocol agreement and various national phaseout timetables. As the research, engineering development, and manufacturing investment decisions have ensued to prepare for this transition away from CFCs, the climate change issue has emerged and there has recently been increased attention on the direct global warming potential (GWP) of the fluorocarbon alternatives as greenhouse gases. However, there has been less focus on the indirect global warming effect arising from end-use energy changes and associated CO{sub 2} emissions. A study was undertaken to address these combined global warming effects. A concept of Total Equivalent Warming Impact (TEWI) was developed for combining the direct and indirect effects and was used for evaluating CFC-replacement options available in the required CFC transition time frame. Analyses of industry technology surveys indicate that CFC-user industries have made substantial progress toward near-equal energy efficiency with many HCFC/HFC alternatives. The findings also bring into question the relative importance of the direct effect in many applications and stress energy efficiency when searching for suitable CFC alternatives. For chillers, household refrigerators, and unitary air-conditioning or heat pump equipment, changes in efficiency of only 2--5% would have a greater effect on future TEWI than completely eliminating the direct effect.

  4. Global warming impacts of CFC alternative technologies: Combining fluorocarbon and CO[sub 2] effects

    SciTech Connect

    Fairchild, P.D.; Fischer, S.K.; Hughes, P.J.

    1992-01-01

    Chlorofluorocarbons (CFCs) are on their way out, due to their role in stratospheric ozone depletion and the related international Montreal Protocol agreement and various national phaseout timetables. As the research, engineering development, and manufacturing investment decisions have ensued to prepare for this transition away from CFCs, the climate change issue has emerged and there has recently been increased attention on the direct global warming potential (GWP) of the fluorocarbon alternatives as greenhouse gases. However, there has been less focus on the indirect global warming effect arising from end-use energy changes and associated CO[sub 2] emissions. A study was undertaken to address these combined global warming effects. A concept of Total Equivalent Warming Impact (TEWI) was developed for combining the direct and indirect effects and was used for evaluating CFC-replacement options available in the required CFC transition time frame. Analyses of industry technology surveys indicate that CFC-user industries have made substantial progress toward near-equal energy efficiency with many HCFC/HFC alternatives. The findings also bring into question the relative importance of the direct effect in many applications and stress energy efficiency when searching for suitable CFC alternatives. For chillers, household refrigerators, and unitary air-conditioning or heat pump equipment, changes in efficiency of only 2--5% would have a greater effect on future TEWI than completely eliminating the direct effect.

  5. Global warming implications of non-fluorocarbon technologies as CFC replacements

    SciTech Connect

    Fischer, S.K.; Tomlinson, J.J.

    1993-12-31

    Many technologies could be developed for use in place of conventional compression systems for refrigeration and air conditioning. Comparisons of the global warming impacts using TEWI (Total Equivalent Warming Impact) can be used to identify alternatives that have the potential for lower environmental impacts than electric-driven vapor compression systems using HCFCs and HFCs. Some options, such as secondary heat transfer loops in commercial refrigeration systems to reduce refrigerant charge and emission rates, could be useful in reducing the losses of refrigerants to the atmosphere. Use of ammonia instead of a fluorocarbon in a system with a secondary loop offers only a small potential for decreasing TEWI, and this may not warrant the increased complexity and risks of using ammonia in a retail sales environment. A few technologies, such as adsorption heat pumps, have efficiency levels that show reduced TEWI levels compared to conventional and state of the art compression systems, and further development could lead to an even more favorable comparison. Health and safety risks of the alternative technologies and the materials they employ must also be considered.

  6. Evaluation of the acute cardiac and central nervous system effects of the fluorocarbon trifluoromethane in baboons

    SciTech Connect

    Branch, C.A.; Goldberg, D.A.; Ewing, J.R.; Butt, S.S.; Gayner, J.; Fagan, S.C.

    1994-12-31

    The gaseous fluorocarbon trifluoromethane has recently been investigated for its potential as an in vivo gaseous indicator for nuclear magnetic resonance studies of brain perfusion. Trifluoromethane may also have significant value as a replacement for chlorofluorocarbon fire retardants. Because of possible species-specific cardiotoxic and anesthetic properties, the toxicological evaluation of trifluoromethane in primates (Papio anubis) is necessary prior to its evaluation in humans. We report the acute cardiac and central nervous system effects of trifluoromethane in eight anesthetized baboons. A dose-response effect was established for respiratory rate, electroencephalogram, and cardiac sinus rate, which exhibited a stepwise decrease from 10% trifluoromethane. No spontaneous arrhythmias were noted, and arterial blood pressure remained unchanged at any inspired level. Intravenous epinephrine infusions (1 {mu}g/kg) induced transient cardiac arrhythmia in 1 animal only at 70% FC-23 (v/v) trifluoromethane. Trifluoromethane appears to induce mild dose-related physiological changes at inspired levels of 30% or more, indicative of an anesthetic effect. These data suggest that trifluoromethane may be safe to use in humans, without significant adverse acute effects, at an inspired level of 30%. 23 refs., 3 figs., 3 tabs.

  7. Surface-Morphology-Induced Hydrophobicity of Fluorocarbon Films Grown by a Simultaneous Etching and Deposition Process

    NASA Astrophysics Data System (ADS)

    Fang, J. S.; Lin, C. S.; Huang, Y. Y.; Chin, T. S.

    2015-08-01

    Development of facile methods to prepare hydrophobic films is of great important. We report fluorocarbon films deposited by a simple plasma-assisted chemical vapor deposition method using C3F8 and C2H2 with extra Ar and/or O2 gases. The surface characteristics of the films were examined by scanning electron microscopy, atomic force microscopy, and x-ray photoelectron spectroscopy. The hydrophobic and oleophobic properties of the films were evaluated by measurements of static contact angle. The results showed that the film deposited with C3F8, C2H2, Ar, and O2 exhibited a water contact angle of 114°, hexadecane contact angle of 45°, and transmittance of 94.5%. Photoelectron spectra further revealed that the films contained mainly CF and CF2 bonds and thus a high F/C ratio. Introduction of O2 increased the F/C ratio, which combined with the stripe-like surface of the films achieved better hydrophobicity.

  8. Ultralow-k silicon containing fluorocarbon films prepared by plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Jin, Yoonyoung; Ajmera, P. K.; Lee, G. S.; Singh, Varshni

    2005-09-01

    Low dielectric constant materials as interlayer dielectrics (ILDs) offer a way to reduce the RC time delay in high-performance ultra-large-scale integration (ULSI) circuits. Fluorocarbon films containing silicon have been developed for interlayer applications below 50-nm linewidth technology. The preparation of the films was carried out by plasma-enhanced chemical vapor deposition (PECVD) using gas precursors of tetrafluorocarbon as the source of active species and disilane (5 vol.% in helium) as a reducing agent to control the ratio of F/C in the films. The basic properties of the low dielectric constant (low-k) interlayer dielectric films are studied as a function of the fabrication process parameters. The electrical, mechanical, chemical, and thermal properties were evaluated including dielectric constant, surface planarity, hardness, residual stress, chemical bond structure, and shrinkage upon heat treatments. The deposition process conditions were optimized for film thermal stability while maintaining a relative dielectric value as low as 2.0. The average breakdown field strength was 4.74 MV/cm. The optical energy gap was in the range 2.2 2.4 eV. The hardness and residual stress in the optimized processed SiCF films were, respectively, measured to be in the range 1.4 1.78 GPa and in the range 11.6 23.2 MPa of compressive stress.

  9. Surface modification of silicon-containing fluorocarbon films prepared by plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Jin, Yoonyoung; Desta, Yohannes; Goettert, Jost; Lee, G. S.; Ajmera, P. K.

    2005-07-01

    Surface modification of silicon-containing fluorocarbon (SiCF) films achieved by wet chemical treatments and through x-ray irradiation is examined. The SiCF films were prepared by plasma-enhanced chemical vapor deposition, using gas precursors of tetrafluoromethane and disilane. As-deposited SiCF film composition was analyzed by x-ray photoelectron spectroscopy. Surface modification of SiCF films utilizing n-lithiodiaminoethane wet chemical treatment is discussed. Sessile water-drop contact angle changed from 95°+/-2° before treatment to 32°+/-2° after treatment, indicating a change in the film surface characteristics from hydrophobic to hydrophilic. For x-ray irradiation on the SiCF film with a dose of 27.4 kJ/cm3, the contact angle of the sessile water drop changed from 95°+/-2° before radiation to 39°+/-3° after x-ray exposure. The effect of x-ray exposure on chemical bond structure of SiCF films is studied using Fourier transform infrared measurements. Electroless Cu deposition was performed to test the applicability of the surface modified films. The x-ray irradiation method offers a unique advantage in making possible surface modification in a localized area of high-aspect-ratio microstructures. Fabrication of a Ti-membrane x-ray mask is introduced here for selective surface modification using x-ray irradiation.

  10. Biocolonizable keratoprosthesis with a microporous fluorocarbon skirt: a two-year study

    NASA Astrophysics Data System (ADS)

    Legeais, Jean-Marc; Renard, Gilles; Parel, Jean-Marie A.; Savoldelli, Michele; Pouliquen, Yves

    1994-06-01

    Most complications of keratoprosthesis (KPro) occur at the tissue-to-implant interface. The ideal prosthesis would eliminate this interface by having the tissue actually grown into the support material forming the haptic. We present a 2-year clinical human study of a novel biocolonizable KPro on 24 eyes of 24 patients. To promote tissue stability, a 9 mm (Phi) skirt made of a new microporous fluorocarbon was used. The optical core or the KPro optic was made of a medical grade polymethylmetacrylate (PMMA) commonly used world-wide to fabricate intraocular lenses. The optic was 5 mm in diameter and 2.67 mm long. The average follow-up was 14 months. Mean corrected visual acuity was 20/100. Anatomic failures occurred in 5 cases in the first year (1 lens dislocation, 1 endophthalmitis, 3 extrusions). These preliminary results appear encouraging. However, we did not eliminate all the complications with this biocompatible inert microporous polymer. Intensive research in mechanical, chemical, and surface biocompatibility is required to develop a true artificial cornea.

  11. Effect of nonsinusoidal bias waveforms on ion energy distributions and fluorocarbon plasma etch selectivity

    SciTech Connect

    Agarwal, Ankur; Kushner, Mark J.

    2005-09-15

    The distributions of ion energies incident on the wafer significantly influence feature profiles and selectivity during plasma etching. Control of ion energies is typically obtained by varying the amplitude or frequency of a radio frequency sinusoidal bias voltage applied to the substrate. The resulting ion energy distribution (IED), though, is generally broad. Controlling the width and shape of the IED can potentially improve etch selectivity by distinguishing between threshold energies of surface processes. In this article, control of the IED was computationally investigated by applying a tailored, nonsinusoidal bias waveform to the substrate of an inductively coupled plasma. The waveform we investigated, a quasi-dc negative bias having a short positive pulse each cycle, produced a narrow IED whose width was controllable based on the length of the positive spike and frequency. We found that the selectivity between etching Si and SiO{sub 2} in fluorocarbon plasmas could be controlled by adjusting the width and energy of the IED. Control of the energy of a narrow IED enables etching recipes that transition between speed and selectivity without change of gas mixture.

  12. Comprehensive testing to measure the response of fluorocarbon rubber (FKM) to Hanford tank waste simulant

    SciTech Connect

    NIGREY,PAUL J.; BOLTON,DENNIS L.

    2000-02-01

    This report presents the findings of the Chemical Compatibility Program developed to evaluate plastic packaging components that may be incorporated in packaging mixed-waste forms for transportation. Consistent with the methodology outlined in this report, the authors performed the second phase of this experimental program to determine the effects of simulant Hanford tank mixed wastes on packaging seal materials. That effort involved the comprehensive testing of five plastic liner materials in an aqueous mixed-waste simulant. The testing protocol involved exposing the materials to {approximately}143, 286, 571, and 3,670 Krad of gamma radiation and was followed by 7-, 14-, 28-, 180-day exposures to the waste simulant at 18, 50, and 60 C. Fluorocarbon (FKM) rubber samples subjected to the same protocol were then evaluated by measuring seven material properties: specific gravity, dimensional changes, mass changes, hardness, compression set, vapor transport rates, and tensile properties. From the analyses, they determined that FKM rubber is not a good seal material to withstand aqueous mixed wastes having similar composition to the one used in this study. They have determined that FKM rubber has limited chemical durability after exposure to gamma radiation followed by exposure to the Hanford tank simulant mixed waste at elevated temperatures above 18 C.

  13. Absorption of gaseous toluene in aqueous solutions of some kinds of fluorocarbon surfactant.

    PubMed

    Xiao, Xiao; Yan, Bo; Fu, Jiamo; Xiao, Xianming

    2015-01-01

    A self-designed device was applied to treat a simulated exhaust gas loaded with toluene by aqueous solutions of five kinds of fluorocarbon surfactant (FS-3100, FS-22, FSN-100, FSO-100 and FSG) under the controlled laboratory conditions. The simulated exhaust gas is generated by a mixture of clean air and toluene vapor, and its toluene concentration can be controlled by changing the volume ratio of the inlet air to the vapor. Two mass transfer methods: liquid-liquid transfer and gas-liquid transfer, were compared for their toluene saturation capacities of these absorbent solutions, and it was found that more toluene was dissolved by the liquid-liquid transfer than by the gas-liquid transfer. According to the saturation capacities of these absorbent solutions and their Henry's Constants, FSO-100 is the best absorbent to treat the simulated exhaust gas and was selected for further experiments. The FSO-100 absorbent solution with a concentration of 0.1 % shows an efficient absorption to the simulated exhaust gas, with a toluene saturation capacity of 4.2 mg/g. Heating distillation (90- 95 oC) is highly efficient to recover toluene from the FSO-100 absorbent solution as well as regenerate it. A toluene recovery of about 85 % was achieved. The regenerated absorption solution can keep its initial toluene absorption capacity during the reuse. PMID:25946961

  14. Feature Profile Evolution of SiO2 Trenches In Fluorocarbon Plasmas

    NASA Technical Reports Server (NTRS)

    Hwang, Helen; Govindan, T. R.; Meyyappan, M.; Arunachalam, Valli; Rauf, Shahid; Coronell, Dan; Carroll, Carol W. (Technical Monitor)

    1999-01-01

    Etching of silicon microstructures for semiconductor manufacturing in chlorine plasmas has been well characterized. The etching proceeds in a two-part process, where the chlorine neutrals passivate the Si surface and then the ions etch away SiClx. However, etching in more complicated gas mixtures and materials, such as etching of SiO2 in Ar/C4F8, requires knowledge of the ion and neutral distribution functions as a function of angle and velocity, in addition to modeling the gas surface reactions. In order to address these needs, we have developed and integrated a suite of models to simulate the etching process from the plasma reactor level to the feature profile evolution level. This arrangement allows for a better understanding, control, and prediction of the influence of equipment level process parameters on feature profile evolution. We are currently using the HPEM (Hybrid Plasma Equipment Model) and PCMCM (Plasma Chemistry Monte Carlo Model) to generate plasma properties and ion and neutral distribution functions for argon/fluorocarbon discharges in a GEC Reference Cell. These quantities are then input to the feature scale model, Simulation of Profile Evolution by Level Sets (SPELS). A surface chemistry model is used to determine the interaction of the incoming species with the substrate material and simulate the evolution of the trench profile. The impact of change of gas pressure and inductive power on the relative flux of CFx and F to the wafer, the etch and polymerization rates, and feature profiles will be examined. Comparisons to experimental profiles will also be presented.

  15. Atmospheric degradation mechanisms of hydrogen containing chlorofluorocarbons (HCFC) and fluorocarbons (HFC)

    NASA Technical Reports Server (NTRS)

    Zellner, Reinhard

    1990-01-01

    The current knowledge of atmospheric degradation of hydrogen containing chlorofluorocarbons (HCFC 22 (CHClF2), HCFC 123 (CHCl2CF3), HCFC 124 (CHClFCF3), HCFC 141b (CFCl2CH3), HCFC 142b (CF2ClCH3)) and fluorocarbons (HFC 125 (CHF2CF3), HFC 134a (CH2FCF3), HFC 152a (CHF2CH3)) is assessed. Except for the initiation reaction by OH radicals, there are virtually no experimental data available concerning the subsequent oxidative breakdown of these molecules. However, from an analogy to the degradation mechanisms of simple alkanes, some useful guidelines as to the expected intermediates and final products can be derived. A noteable exception from this analogy, however, appears for the oxi-radicals. Here, halogen substitution induces new reaction types (C-Cl and C-C bond ruptures) which are unknown to the unsubstituted analogues and which modify the nature of the expected carbonyl products. Based on an evaluation of these processes using estimated bond strength data, the following simplified rules with regards to the chlorine content of the HCFC's may be deduced: (1) HCFC's containing one chlorine atom such as 22 and 142b seem to release their chlorine content essentially instantaneous with the initial attack on the parent by OH radicals, and for HCFC 124, such release is apparently prevented; (2) HCFC's such as 123 and 141b with two chlorine atoms are expected to release only one of these instantaneously; and the second chlorine atom may be stored in potentially long-lived carbonyl compounds such as CF3CClO or CClFO.

  16. Synthesis and surface properties of polyurethane end-capped with hybrid hydrocarbon/fluorocarbon double-chain phospholipid.

    PubMed

    Li, Jiehua; Zhang, Yi; Yang, Jian; Tan, Hong; Li, Jianshu; Fu, Qiang

    2013-05-01

    To improve hemocompatibility of biomedical polyurethanes (PUs), a series of new fluorinated phospholipid end-capped polyurethanes (FPCPUs) as blending PU additives were designed and synthesized using diphenyl methane diisocyanate and 1,4-butanediol as hard segment, poly(tetramethylene glycol), polypropylene glycol, polycarbonate diols, and polyethylene glycol as soft segments, respectively, aminofunctionalized hybrid hydrocarbon/fluorocarbon double-chain phospholipid as end-capper. The bulk structures and surface properties of the obtained FPCPUs were fully characterized by (1)H NMR, Fourier transform infrared, gel permeation chromatography, X-ray photoelectron spectroscopy, differential scanning calorimetry, atomic force microscopy, and water contact angle measurement. It was found that the phosphatidylcholine groups could enrich on the surfaces and subsurfaces with the help of the fluorocarbon chains and self-assemble into mimic biomembrane on these polymer surfaces. These surfaces could effectively suppress fibrinogen adsorption, as evaluated by enzyme-linked immunosorbent assay method. Our work indicates that the FPCPUs should be one of the most potential modified additives for enhancing hemocompatibility of traditional medical PUs. PMID:23077090

  17. ToF SIMS analysis of a fluorocarbon-grafted PET with a gold cluster ion source

    NASA Astrophysics Data System (ADS)

    Zhu, Zhengmao; Kelley, Michael J.

    2006-07-01

    Cluster ions have been recognized as a superb primary species in time of flight secondary ion mass spectroscopy (ToF-SIMS) compared with monatomic primary ions, as they significantly enhance the secondary ion yields from bulk samples. Self-assembled monolayers provide an important system for studying the fundamental mechanism involved in the yield enhancement. We used a gold cluster ion source to analyze a new type of self-assembled monolayer: a fluorocarbon-grafted polyethylene terephthalate. In addition to the structure details, which helped to understand the grafting mechanism, ToF-SIMS analysis revealed that fluorocarbon secondary ion yield enhancements by cluster ions were due to the enhanced sputter efficiency. A larger information depth may also be expected from the enhancement. Both mathematical definitions of damage cross-section and disappearance cross-section were revisited under a new context. Another cross-section parameter, sputter cross-section, was introduced to differentiate the beam induced sputter process from damage process.

  18. 157 nm Pellicles (Thin Films) for Photolithography: Mechanistic Investigation of the VUV and UV-C Photolysis of Fluorocarbons

    SciTech Connect

    Lee, Kwangjoo; Jockusch, Steffen; Turro, Nicholas J.; French, Roger H.; Wheland, Robert C.; Lemon, M F.; Braun, Andre M.; Widerschpan, Tatjana; Dixon, David A.; Li, Jun; Ivan, Marius; Zimmerman, Paul

    2005-06-15

    The use of 157 nm as the next lower wavelength for photolithography for the production of semiconductors has created a need for transparent and radiation-durable polymers for use in soft pellicles, the polymer films which protect the chip from particle deposition. The most promising materials for pellicles are fluorinated polymers, but currently available fluorinated polymers undergo photodegradation and/or photodarkening upon long term exposure to 157 nm irradiation. To understand the mechanism of the photodegradation and photodarkening of fluorinated polymers, mechanistic studies on the photolysis of liquid model fluorocarbons, including perfluorobutylethyl ether and perfluoro-2 H-3-oxa-heptane, were performed employing UV, NMR, FTIR, GC, and GC/MS analyses. All hydrogen-containing compounds showed decreased photostability compared to the fully perfluorinated compounds. Irradiation in the presence of atmospheric oxygen showed reduced photostability compared to deoxygenated samples. Photolysis of the samples was performed at 157, 172, 185, and 254 nm and showed only minor wavelength dependence. Mechanisms for photodegradation of the fluorocarbons are proposed, which involve Rydberg excited states. Time-dependent density functional theory has been used to predict the excitation spectra of model compounds.

  19. Comparative study of the physicochemical properties of aqueous solutions of the hydrocarbon and fluorocarbon surfactants and their ternary mixtures

    NASA Astrophysics Data System (ADS)

    Szymczyk, Katarzyna

    2014-03-01

    Speed of sound and density of aqueous solutions of hydrocarbon p-(1,1,3,3-tetramethylbutyl) phenoxypoly(ethyleneglycols) (Triton X-100 (TX100), Triton X-165 (TX165)) and fluorocarbon (Zonyl FSN-100 (FSN100), Zonyl FSO-100 (FSO100)) surfactants as well as their ternary mixtures were measured at 293 K. Taking into account these values and the literature data of the surface tension and viscosity of the studied systems, the values of the isentropic compressibility, apparent specific adiabatic compressibility, hydration number, apparent specific volume and Jones Dole's A and B-coefficients were determined. For the systems containing FSO100 also the values of dB/dT were determined on the basis of the values of viscosity measured at different temperatures. Next, the calculated thermodynamic properties have been discussed in the term of intermolecular interactions between the components of the mixtures.

  20. X-ray photoelectron spectroscopic study of Ge2Sb2Te5 etched by fluorocarbon inductively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Kang, S.-K.; Oh, J. S.; Park, B. J.; Kim, S. W.; Lim, J. T.; Yeom, G. Y.; Kang, C. J.; Min, G. J.

    2008-07-01

    X-ray photoelectron spectroscopy was used to determine the level of surface fluorination damage of Ge2Sb2Te5 (GST) etched by fluorocarbon gases at different F/C ratios. When blank GST was etched, the gas with a higher F/C ratio produced a thinner C-F polymer on the etched surface but fluorinated Ge, Sb, and Te compounds were observed in the remaining GST. When the sidewall of the etched GST features was investigated, a thicker fluorinated layer was observed on the GST sidewall etched by the higher F/C ratio gas, indicating more fluorination due to the difficulty in preventing F diffusion into the GST through the thinner C-F layer.

  1. Surface films of short fluorocarbon-hydrocarbon diblocks studied by molecular dynamics simulations: Spontaneous formation of elongated hemimicelles.

    PubMed

    Piñeiro, Angel; Prieto, Gerardo; Ruso, Juan M; Verdes, Pedro V; Sarmiento, Félix

    2009-01-15

    Using grazing incidence small-angle X-ray scattering (GISAXS), and atomic force microscopy (AFM) it has been recently demonstrated that linear fluorocarbon-hydrocarbon diblocks (FnHm) self-assemble in water/air interfaces forming elongated and circular hemimicelles. Those structures have been observed for diblocks with at least eight fluorinated carbons. Based on the lack of a collapse pressure for F6H16, and due to the fact that no stable surface pressure values are reached under compression, it has been concluded that these molecules do not form stable monolayers. It has been also suggested that F6H16 and shorter diblocks desorb from the water surface under compression. It is not easy to accept that a significant concentration of so hydrophobic molecules can be stable in aqueous solution even when the employed experimental techniques were not able to clearly detect a well defined structure on the interface. In the present work the adsorption and arrangement of F6H16 and F6H10 at the water surface are studied by molecular dynamics (MD) simulations as a function of the available area per molecule. Starting from a random mixture, the spontaneous formation of elongated hemimicelles is observed for both systems when the area per molecule is higher than approximately 50 A(2). For intermediate areas two pseudo-phases, one rich in hydrocarbons and the other with higher fluorocarbon concentration, are formed. For the systems with less than approximately 30 A(2) available per molecule the formation of multilayers is observed. This is the first time that the dynamics and structure of perfluoroalkane (PFA) films, and in particular of hemimicelles on a liquid surface, are observed and characterized at atomic level. PMID:18977492

  2. Characterization of zeolite structure and fluorocarbon reactivity using solid state NMR and x-ray powder diffraction

    NASA Astrophysics Data System (ADS)

    Ciraolo, Michael Frank

    The research presented in this thesis involves a combination of techniques used to study the structure and interactions zeolites adsorbed with fluorocarbons. This research is specifically aimed at understanding the processes of adsorption, binding, and reactivity of fluorocarbons on cation exchanged faujasite type zeolites. The solid state ion exchange process has also been studied since it is one way to obtain materials with higher exchange levels, which has been shown to effect adsorption and catalytic activity. To improve the understanding of the adsorption and separation processes a time resolved in-situ synchrotron x-ray powder diffraction study has been undertaken. Since faujasite type zeolites have been found to be effective in separating mixtures of HFC-134 (CF2HCF2H) and HFC-134a (CFH2CF3) isomers, the adsorption of these fluorocarbons on NaY have been studied. It has been shown that both the extent of loading and the kinetics of the sorption process in molecular sieves can be followed using this technique. A model for the binding of hydrochlorofluorocarbon (HCFC) 124a (CF 2HCF2Cl) adsorbed on NaX at 100K has been determined using a combination x-ray and neutron powder diffraction and solid state NMR. Using Rietveld refinement of the diffraction data, the HCFC molecule was found localized in the zeolite cavities bound on either end by sodium cations in the SII and SIII' positions. The model is consistent with hydrogen bonding between the proton of the HCFC and the framework oxygen. The NMR results further confirm the model and are consistent with Na-F binding and HCFC-framework interactions. Solid-state MAS NMR, synchrotron X-ray powder diffraction and a mass spectrometer and gas chromatograph catalysis system have been used to study the reactivity of HCFC-124a (CF2HCF2Cl) on NaX, Zn 2+-exchanged NaX (ZnX) and Rb+-exchanged NaX (RbX). We have chosen to study HCFC-124a (CF2HCF2Cl) since HCFC-124a can undergo both dehydrofluorination and dehydrochlorination reactions. The preference between these two reactions should be related to the relative importance of the interactions with the basic oxygen atoms and the cations. RbX is considered a basic zeolite while ZnX should have more acidic character, which should be reflected in differences in product distribution. The positions of the exchanged cations and the residual sodium cations of both exchanged zeolites have been located and the products formed during reaction have been identified. To investigate possible methods to achieve high levels of cation substitution, NH4Y has been ion exchanged with solid Rb2CO3 to form RbY. This process has been followed with x-ray powder diffraction, mass spectrometry and NMR. It has been shown that exchange begins on grinding and no rubidium oxide or new carbonate phases were observed to form during the exchange. The positions of the cations of the final exchanged RbY product have been located with Rietveld analysis. It has also been shown that 1H and 87Rb MAS NMR is very sensitive to the level of hydration of the zeolite and has been used to follow the solid state exchange process.

  3. Light-responsive nanoparticles with wettability changing from hydrophobicity to hydrophilicity and their application towards highly hydrophilic fluorocarbon coatings

    NASA Astrophysics Data System (ADS)

    Lin, Baozhong; Zhou, Shuxue

    2015-12-01

    Novel functional silica nanoparticles (SiO2-NBS-F) with irreversible light-responsive wettability were prepared by grafting of a light-responsive silane coupling agent (NBS) and further bonding with hydrophobic segments via a click reaction. The NBS was synthesized using an o-nitrobenzyl alcohol derivative of the photolabile protecting group. The SiO2-NBS-F nanoparticles exhibited considerable change of wettability from near-superhydrophobicity to near-superhydrophilicity after UV irradiation. The changing mechanism of wettability was confirmed by UV-Vis absorption spectra and X-ray photoelectron spectra. The SiO2-NBS-F nanoparticles were incorporated into fluorocarbon FEVE coatings by simple mixing. The nanoparticles occurred at the surface of the dried coatings even though their content was as low as 5 wt%, being due to their low surface free energy. The wettability of the SiO2-NBS-F filled FEVE coatings could transform from hydrophobicity (WCA 106.4°) to hydrophilicity (WCA 33.3°) after UV irradiation. It demonstrates that SiO2-NBS-F nanoparticles are useful to acquire highly hydrophilic surface for organic coatings.

  4. Shape Modification of Water-in-CO2 Microemulsion Droplets through Mixing of Hydrocarbon and Fluorocarbon Amphiphiles.

    PubMed

    Yan, Ci; Sagisaka, Masanobu; Rogers, Sarah E; Hazell, Gavin; Peach, Jocelyn; Eastoe, Julian

    2016-02-16

    An oxygen-rich hydrocarbon (HC) amphiphile has been developed as an additive for supercritical CO2 (scCO2). The effects of this custom-designed amphiphile have been studied in water-in-CO2 (w/c) microemulsions stabilized by analogous fluorocarbon (FC) surfactants, nFG(EO)2, which are known to form spherical w/c microemulsion droplets. By applying contrast-variation small-angle neutron scattering (CV-SANS), evidence has been obtained for anisotropic structures in the mixed systems. The shape transition is attributed to the hydrocarbon additive, which modifies the curvature of the mixed surfactant films. This can be considered as a potential method to enhance physicochemical properties of scCO2 through elongation of w/c microemulsion droplets. More importantly, by studying self-assembly in these mixed systems, fundamental understanding can be developed on the packing of HC and FC amphiphiles at water/CO2 interfaces. This provides guidelines for the design of fluorine-free CO2 active surfactants, and therefore, practical industrial scale applications of scCO2 could be achieved. PMID:26807476

  5. Applications of a Chemically Adsorbed Monomolecular Layer Having a Fluorocarbon Chain as an Anti-Contamination Film

    NASA Astrophysics Data System (ADS)

    Ogawa, Kazufumi; Ohtake, Tadashi; Nomura, Takaiki; Soga, Mamoru; Mino, Norihisa

    2000-12-01

    Monomolecular layers having a fluorocarbon chain were developed and made suitable for practical use as anti-contamination films for glasses, such as front door window glass plates of automobiles and window glass plates of electric ovens or microwave ovens, and also for stainless steel applications, such as covers of electric rice cookers, by using a chemical adsorption technique for the first time in the world. The layer was anchored to the substrate surface through covalent bonds. Thus the layer did not peel off and was durable against rubbing and scratching. As the film thickness was from about 1 to 2 nm, the layer was also optically transparent and the luster and color tone of the substrates was maintained. The lowest surface tension obtained was 8.2 mN/m, which is about a half that of Teflon. Although thermo-durability was a little low in comparison with that of Teflon, the production cost was lower. Thus this anti-contamination film should be very useful in the field of anti-contamination surface treatment.

  6. Mesoporous fluorocarbon-modified silica aerogel membranes enabling long-term continuous CO2 capture with large absorption flux enhancements.

    PubMed

    Lin, Yi-Feng; Chen, Chien-Hua; Tung, Kuo-Lun; Wei, Te-Yu; Lu, Shih-Yuan; Chang, Kai-Shiun

    2013-03-01

    The use of a membrane contactor combined with a hydrophobic porous membrane and an amine absorbent has attracted considerable attention for the capture of CO2 because of its extensive use, low operational costs, and low energy consumption. The hydrophobic porous membrane interface prevents the passage of the amine absorbent but allows the penetration of CO2 molecules that are captured by the amine absorbent. Herein, highly porous SiO2 aerogels modified with hydrophobic fluorocarbon functional groups (?CF3 ) were successfully coated onto a macroporous Al2 O3 membrane; their performance in a membrane contactor for CO2 absorption is discussed. The SiO2 aerogel membrane modified with ?CF3 functional groups exhibits the highest CO2 absorption flux and can be continuously operated for CO2 absorption for extended periods of time. This study suggests that a SiO2 aerogel membrane modified with ?CF3 functional groups could potentially be used in a membrane contactor for CO2 absorption. Also, the resulting hydrophobic SiO2 aerogel membrane contactor is a promising technology for large-scale CO2 absorption during the post-combustion process in power plants. PMID:23417984

  7. Kinetics of Nanoscale Self-Assembly Measured on Liquid Drops by Macroscopic Optical Tensiometry: From Mercury to Water and Fluorocarbons.

    PubMed

    Haimov, Boris; Iakovlev, Anton; Glick-Carmi, Rotem; Bloch, Leonid; Rich, Benjamin B; Müller, Marcus; Pokroy, Boaz

    2016-03-01

    Various molecules are known to form self-assembled monolayers (SAMs) on the surface of liquids. We present a simple method of investigating the kinetics of such SAM formation on sessile drops of various liquids such as mercury, water and fluorocarbon. To measure the surface tension of the drops we used an optical tensiometer that calculates the surface tension from the axisymmetric drop shape and the Young-Laplace relation. In addition, we estimated the SAM surface coverage fraction from the surface tension measured by other techniques. With this methodology we were able to optically detect concentrations as low as tenths of ppb increments of SAM molecules in solution and to compare the kinetics of SAM formation measured as a function of molecule concentration or chain length. The analysis is performed in detail for the case of alkanethiols on mercury and then shown to be more general by investigating the case of SAM formation of stearic acid on a water droplet in hexadecane and of perfluorooctanol on a Fluorinert FC-40 droplet in ethanol. PMID:26790500

  8. Influence of the 316 L stainless steel interface on the stability and barrier properties of plasma fluorocarbon films.

    PubMed

    Lewis, François; Cloutier, Maxime; Chevallier, Pascale; Turgeon, Stéphane; Pireaux, Jean-Jacques; Tatoulian, Michael; Mantovani, Diego

    2011-07-01

    Coatings are known to be one of the more suited strategies to tailor the interface between medical devices and the surrounding cells and tissues once implanted. The development of coatings and the optimization of their adhesion and stability are of major importance. In this work, the influence of plasma etching of the substrate on a plasma fluorocarbon ultrathin coating has been investigated with the aim of improving the stability and the corrosion properties of coated medical devices. The 316 L stainless steel interface was subjected to two different etching sequences prior to the plasma deposition. These plasma etchings, with H(2) and C(2)F(6) as gas precursors, modified the chemical composition and the thickness of the oxide layer and influenced the subsequent polymerization. The coating properties were evaluated using flat substrates submitted to deformation, aging into aqueous medium and corrosion tests. X-ray photoelectron spectroscopy (XPS), time of flight-secondary ion mass spectrometry (ToF-SIMS), ellipsometry, and atomic force microscopy (AFM) were performed to determine the effects of the deformation and the aging on the chemistry and morphology of the coated samples. Analyses showed that plasma etchings were essential to promote reproducible polymerization and film growth. However, the oxide layer thinning due to the etching lowered the corrosion resistance of the substrate and affected the stability of the interface. Still, the deformed samples did not exhibited adhesion and cohesion failure before and after the aging. PMID:21545130

  9. Relationship between gas-phase chemistries and surface processes in fluorocarbon etch plasmas: A process rate model

    SciTech Connect

    Sant, S. P.; Nelson, C. T.; Overzet, L. J.; Goeckner, M. J.

    2009-07-15

    In a typical plasma tool, both etch and deposition occur simultaneously. Extensive experimental measurements are used to help develop a general model of etch and deposition processes. This model employs reaction probabilities, or surface averaged cross sections, to link the measurable surface processes, etch and deposition, to the flux of various species to the surfaces. Because the cross sections are quantum mechanical in nature, this surface rate model should be applicable to many low temperature plasma processing systems. Further, the parameters that might be important in reaction cross sections are known from quantum mechanics, e.g., species, energy, temperature, and impact angle. Such parameters might vary from system to system, causing the wide processing variability observed in plasma tools. Finally the model is used to compare measurements of ion flux, ion energy, and fluorocarbon radical flux to the measured process rates. It is found that the model appears to be consistent with calculations of gain/loss rates for the various radicals present in the discharge as well as measured etch and deposition rates.

  10. The cooling capabilities of C2F6/C3F8 saturated fluorocarbon blends for the ATLAS silicon tracker

    NASA Astrophysics Data System (ADS)

    Bates, R.; Battistin, M.; Berry, S.; Bitadze, A.; Bonneau, P.; Bousson, N.; Boyd, G.; Botelho-Direito, J.; Crespo-Lopez, O.; DiGirolamo, B.; Doubek, M.; Giugni, D.; Hallewell, G.; Lombard, D.; Katunin, S.; McMahon, S.; Nagai, K.; Robinson, D.; Rossi, C.; Rozanov, A.; Vacek, V.; Zwalinski, L.

    2015-03-01

    We investigate and address the performance limitations of the ATLAS silicon tracker fluorocarbon evaporative cooling system operation in the cooling circuits of the barrel silicon microstrip (SCT) sub-detector. In these circuits the minimum achievable evaporation temperatures with C3F8 were higher than the original specification, and were thought to allow an insufficient safety margin against thermal runaway in detector modules subject to a radiation dose initially foreseen for 10 years operation at LHC. We have investigated the cooling capabilities of blends of C3F8 with molar admixtures of up to 25% C2F6, since the addition of the more volatile C2F6 component was expected to allow a lower evaporation temperature for the same evaporation pressure.A custom built recirculator allowed the in-situ preparation of C2F6/C3F8 blends. These were circulated through a representative mechanical and thermal setup reproducing an as-installed ATLAS SCT barrel tracker cooling circuit. Blend molar compositions were verified to a precision of 3.10-3 in a custom ultrasonic instrument.Thermal measurements in a range of C2F6/C3F8 blends were compared with measurements in pure C3F8. These indicated that a blend with 25% C2F6 would allow a reduction in evaporation temperature of around 9oC to below -15oC, even at the highest module power dissipations envisioned after 10 years operation at LHC. Such a reduction would allow more than a factor two in safety margin against temperature dependant leakage power induced thermal runaway.Furthermore, a blend containing up to 25% C2F6 could be circulated without changes to the on-detector elements of the existing ATLAS inner detector evaporative cooling system.

  11. Automatic fitting procedures for EPR spectra of disordered systems: matrix diagonalization and perturbation methods applied to fluorocarbon radicals.

    PubMed

    Lund, A; Andersson, P; Eriksson, J; Hallin, J; Johansson, T; Jonsson, R; Löfgren, H; Paulin, C; Tell, A

    2008-05-01

    Two types of automatic fitting procedures for EPR spectra of disordered systems have been developed, one based on matrix diagonalization of a general spin Hamiltonian, the other on 2nd order perturbation theory. The first program is based on a previous Fortran code complemented with a newly written interface in Java to provide user-friendly in and output. The second is intended for the special case of free radicals with several relatively weakly interacting nuclei, in which case the general method becomes slow. A least squares' fitting procedure utilizing analytical or numerical derivatives of the theoretically calculated spectrum with respect to the g- and hyperfine structure (hfs) tensors was used to refine those parameters in both cases. 'Rigid limit' ESR spectra from radicals in organic matrices and in polymers, previously studied experimentally at low temperature, were analyzed by both methods. Fluorocarbon anion radicals could be simulated, quite accurately with the exact method, whereas automatic fitting on, e.g. the c-C(4)F(8)(-) anion radical is only feasible with the 2nd order approximative treatment. Initial values for the (19)F hfs tensors estimated by DFT calculations were quite close to the final. For neutral radicals of the type XCF(2)CF(2)* the refinement of the hfs tensors by the exact method worked better than the approximate. The reasons are discussed. The ability of the fitting procedures to recover the correct magnetic parameters of disordered systems was investigated by fittings to synthetic spectra with known hfs tensors. The exact and the approximate methods are concluded to be complementary, one being general, but limited to relatively small systems, the other being a special treatment, suited for S=1/2 systems with several moderately large hfs. PMID:18006375

  12. The effects of changing deposition conditions on the similarity of sputter-deposited fluorocarbon thin films to bulk PTFE

    NASA Astrophysics Data System (ADS)

    Zandona, Philip

    Solid lubrication of space-borne mechanical components is essential to their survival and the continued human exploration of space. Recent discoveries have shown that PTFE when blended with alumina nanofillers exhibits greatly improved physical performance properties, with wear rates being reduced by several orders of magnitude. The bulk processes used to produce the PTFE-alumina blends are limiting. Co-sputter deposition of PTFE and a filler material overcomes several of these limitations by enabling the reduction of particle size to the atomic level and also by allowing for the even coating of the solid lubricant on relatively large areas and components. The goal of this study was to establish a baseline performance of the sputtered PTFE films as compared to the bulk material, and to establish deposition conditions that would result in the most bulk-like film possible. In order to coax change in the structure of the sputtered films, sputtering power and deposition temperature were increased independently. Further, post-deposition annealing was applied to half of the deposited film in an attempt to affect change in the film structure. Complications in the characterization process due to increasing film thickness were also examined. Bulk-like metrics for characterization processes the included Fourier transform infrared spectroscopy (FTIR), X-ray spectroscopy (XPS), nanoindentation via atomic force microscopy, and contact angle of water on surface measurements were established. The results of the study revealed that increasing sputtering power and deposition temperature resulted in an increase in the similarity between the fluorocarbon films and the bulk PTFE, at a cost of affecting the potential of the film thicknesses, either by affecting the deposition process directly, or by decreasing the longevity of the sputtering targets.

  13. Thermochemical Properties Enthalpy, Entropy, and Heat Capacity of C1-C4 Fluorinated Hydrocarbons: Fluorocarbon Group Additivity.

    PubMed

    Wang, Heng; Castillo, Álvaro; Bozzelli, Joseph W

    2015-07-23

    Enthalpies of formation for 14 C2–C4 fluorinated hydrocarbons were calculated with nine popular ab initio and density functional theory methods: B3LYP, CBS-QB3, CBS-APNO, M06, M06-2X, ωB97X, G4, G4(MP2)-6X, and W1U via several series of isodesmic reactions. The recommended ideal gas phase ΔHf298° (kcal mol(–1)) values calculated in this study are the following: −65.4 for CH3CH2F; −70.2 for CH3CH2CH2F; −75.3 for CH3CHFCH3; −75.2 for CH3CH2CH2CH2F; −80.3 for CH3CHFCH2CH3; −108.1 for CH2F2; −120.9 for CH3CHF2; −125.8 for CH3CH2CHF2; −133.3 for CH3CF2CH3; −166.7 for CHF3; −180.5 for CH3CF3; −185.5 for CH3CH2CF3; −223.2 for CF4; and −85.8 for (CH3)3CF. Entropies (S298° in cal mol(–1) K(–1)) were estimated using B3LYP/6-31+G(d,p) computed frequencies and geometries. Rotational barriers were determined and hindered internal rotational contributions for S298°, and Cp(T) were calculated using the rigid rotor harmonic oscillator approximation, with direct integration over energy levels of the intramolecular rotation potential energy curve. Thermochemical properties for the fluorinated carbon groups C/C/F/H2, C/C2/F/H, C/C/F2/H, C/C2/F2, and C/C/F3 were derived from the above target fluorocarbons. Previously published enthalpies and groups for 1,2-difluoroethane, 1,1,2-trifluoroethane, 1,1,2,2-tetrafluoroethane, 1,1,1,2-tetrafluoroethane, 1,1,1,2,2-pentafluoroethane, 2-fluoro-2-methylpropane that were previously determined via work reaction schemes are revised using updated reference species values. Standard deviations are compared for the calculation methods. PMID:26066097

  14. X-ray photoelectron spectroscopic study of Ge{sub 2}Sb{sub 2}Te{sub 5} etched by fluorocarbon inductively coupled plasmas

    SciTech Connect

    Kang, S.-K.; Oh, J. S.; Park, B. J.; Kim, S. W.; Lim, J. T.; Yeom, G. Y.; Kang, C. J.; Min, G. J.

    2008-07-28

    X-ray photoelectron spectroscopy was used to determine the level of surface fluorination damage of Ge{sub 2}Sb{sub 2}Te{sub 5} (GST) etched by fluorocarbon gases at different F/C ratios. When blank GST was etched, the gas with a higher F/C ratio produced a thinner C-F polymer on the etched surface but fluorinated Ge, Sb, and Te compounds were observed in the remaining GST. When the sidewall of the etched GST features was investigated, a thicker fluorinated layer was observed on the GST sidewall etched by the higher F/C ratio gas, indicating more fluorination due to the difficulty in preventing F diffusion into the GST through the thinner C-F layer.

  15. Synthesis and characterization of fluorocarbon chain end-capped poly(carbonate urethane)s as biomaterials: a novel bilayered surface structure.

    PubMed

    Xie, Xingyi; Tan, Hong; Li, Jiehua; Zhong, Yinping

    2008-01-01

    Poly(carbonate urethane)s (PCUs) are usually considered as biostable elastomers for long-term implantation. However, their hydrolytic stability is still questionable. The biodegradation appears to be initiated by oxidative and hydrolytic substances released by inflammatory cells. Therefore, the biostability of polyurethane might be improved with control of surface structure to reduce inflammatory response. A new type of PCUs end-capped with perfluoro chains was synthesized to explore a new avenue. A fluorinated alcohol, 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluoro-1-octanol (PDFOL), was end-capped to the backbones of PCUs by reaction of the --OH in PDFOL with the --NCO end groups in PCU backbones. Contact angle measurement, X-ray photoelectron spectroscopy, atomic force microscopy, and attenuated total reflectance-Fourier transform infrared spectroscopy were used to examine their surface structure and properties. Elemental analysis, gel permeation chromatography, differential scanning calorimetry, and tensile testing were used to assess bulk chemistry and properties. The fluorocarbon end-capped poly (carbonate urethane)s (FPCUs) maintained the high mechanical properties (about 40 MPa tensile strength) and typical microphase separation structure of polyurethane elastomers. Results from surface analyses revealed the presence of a double-layered structure at the surfaces of the FPCUs. The first one was composed of fluorocarbon tails rising up on the uppermost layer and the second one made up of hard-segments. This novel bilayered surface structure could protect the weak carbonate linkages in soft segments, and consequently, may potentially increase the biostability of this kind of polyurethanes. PMID:17600322

  16. Reductive defluorination of saturated fluorocarbons by organometallic reagents and aryl halide coordination to tungsten(II) and molybdenum(II) by chelating Schiff base ligands

    SciTech Connect

    Harrison, R.G.

    1993-01-01

    Strong organometallic nucleophiles cleave C-F bonds of fluorocarbons such as perfluorodecalin and perfluoro(methylcyclohexane) to afford complexes of the form Cp(CO)[sub 2]FeR, where R is a fluoro aromatic derivative of the perfluorocarbon, when NaCpFe(CO)[sub 2] is used as a nucleophile. Fluoride ion and [Cp(CO)[sub 2]Fe][sub 2] are also recovered in good yields. The reaction occurs at ambient temperature and reaction times vary from one to four hours depending on the substrate used. An electron transfer mechanism is proposed and radical character exists in the intermediates, as evident by hydrogen incorporation into the fluorocarbon products and rate enhancement when the reaction is run in the presence of a hydrogen radical donor. The reactivity patterns of model systems indicate hydrogen incorporation occurred early along the reaction pathway. NaRe(CO)[sub 5] and Ni(P(C[sub 2]H[sub 5])[sub 3])[sub 4] also show reactivity towards the perfluorosubstrates, but NaCpMo(CO)[sub 3] and Na[sub 2]Fe(CO)[sub 4] do not. Aryl-X (X = Cl, Br, I, OCH[sub 3]) groups coordinate to Mo(II) and W(II), through the lone pairs on the atoms, forming seven coordinate metal carbonyls, when chelating nitrogen Schiff base ligands are oxidatively added to W(CO)[sub 3](NCCH[sub 3])[sub 3] or Mo(CO)[sub 3](toluene) in THF. The major mode of reactivity of these coordination compounds is aryl halide dissociation. Competition with typical solvents as monitored by solution IR and ligand equilibrium studies give relative bond strengths. X-ray crystallography shows covalent bonding between the metal and aryl halide groups and the metal geometry is capped octahedral. The aryl halide complexes substitute CO preferentially over the aryl halide when exposed to phosphine donor ligands. Aryl-fluoride coordination was not detected, but halide bridged metal dimers were isolated instead.

  17. Hydrophobicity attainment and wear resistance enhancement on glass substrates by atmospheric plasma-polymerization of mixtures of an aminosilane and a fluorocarbon

    NASA Astrophysics Data System (ADS)

    Múgica-Vidal, Rodolfo; Alba-Elías, Fernando; Sainz-García, Elisa; Pantoja-Ruiz, Mariola

    2015-08-01

    Mixtures of different proportions of two liquid precursors were subjected to plasma-polymerization by a non-thermal atmospheric jet plasma system in a search for a coating that achieves a hydrophobic character on a glass substrate and enhances its wear resistance. 1-Perfluorohexene (PFH) was chosen as a low-surface-energy precursor to promote a hydrophobic character. Aminopropyltriethoxysilane (APTES) was chosen for its contribution to the improvement of wear resistance by the formation of siloxane bonds. The objective of this work was to determine which of the precursors' mixtures that were tested provides the coating with the most balanced enhancement of both hydrophobicity and wear resistance, given that coatings deposited with fluorocarbon-based precursors such as PFH are usually low in resistance to wear and coatings deposited with APTES are generally hydrophilic. The coatings obtained were analyzed by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Fourier Transform Infra-Red (FTIR) spectroscopy, X-ray Photoelectron Spectroscopy (XPS), static Water Contact Angle (WCA) measurements, tribological ball-on-disc tests and contact profilometry. A relationship between the achievement of a hydrophobic character and the modifications to roughness and surface morphology and the incorporation of fluorocarbon groups in the surface chemistry was observed. Also, it was seen that the wear resistance was influenced by the SiOSi content of the coatings. In turn, the SiOSi content appears to be directly related to the percentage of APTES used in the mixture of precursors. The best conjunction of hydrophobicity and wear resistance in this work was found in the sample that was coated using a mixture of APTES and PFH in proportions of 75 and 25%, respectively. Its WCA (100.2 ± 7.5°) was the highest of all samples that were measured and more than three times that of the uncoated glass (31 ± 0.7°). This sample underwent a change from a hydrophilic to a hydrophobic character. It also had the lowest wear rate of the hydrophobic samples obtained in this work, with a reduction of 28.8% in the wear rate of the uncoated glass.

  18. Fluorocarbon assisted atomic layer etching of SiO2 and Si using cyclic Ar/C4F8 and Ar/CHF3 plasma

    DOE PAGESBeta

    Metzler, Dominik; Li, Chen; Engelmann, Sebastian; Bruce, Robert L.; Joseph, Eric A.; Oehrlein, Gottlieb S.

    2015-11-11

    The need for atomic layer etching (ALE) is steadily increasing as smaller critical dimensions and pitches are required in device patterning. A flux-control based cyclic Ar/C4F8 ALE based on steady-state Ar plasma in conjunction with periodic, precise C4F8 injection and synchronized plasma-based low energy Ar+ ion bombardment has been established for SiO2.1 In this work, the cyclic process is further characterized and extended to ALE of silicon under similar process conditions. The use of CHF3 as a precursor is examined and compared to C4F8. CHF3 is shown to enable selective SiO2/Si etching using a fluorocarbon (FC) film build up. Othermore » critical process parameters investigated are the FC film thickness deposited per cycle, the ion energy, and the etch step length. Etching behavior and mechanisms are studied using in situ real time ellipsometry and X-ray photoelectron spectroscopy. Silicon ALE shows less self-limitation than silicon oxide due to higher physical sputtering rates for the maximum ion energies used in this work, ranged from 20 to 30 eV. The surface chemistry is found to contain fluorinated silicon oxide during the etching of silicon. As a result, plasma parameters during ALE are studied using a Langmuir probe and establish the impact of precursor addition on plasma properties.« less

  19. Impact of etching kinetics on the roughening of thermal SiO{sub 2} and low-k dielectric coral films in fluorocarbon plasmas

    SciTech Connect

    Yin Yunpeng; Sawin, Herbert H.

    2007-07-15

    The impact of etching kinetics and etching chemistries on surface roughening was investigated by etching thermal silicon dioxide and low-k dielectric coral materials in C{sub 4}F{sub 8}/Ar plasma beams in an inductive coupled plasma beam reactor. The etching kinetics, especially the angular etching yield curves, were measured by changing the plasma pressure and the feed gas composition which influence the effective neutral-to-ion flux ratio during etching. At low neutral-to-ion flux ratios, the angular etching yield curves are sputteringlike, with a peak around 60 deg. -70 deg. off-normal angles; the surface at grazing ion incidence angles becomes roughened due to ion scattering related ion-channeling effects. At high neutral-to-ion flux ratios, ion enhanced etching dominates and surface roughening at grazing angles is mainly caused by the local fluorocarbon deposition induced micromasking mechanism. Interestingly, the etched surfaces at grazing angles remain smooth for both films at intermediate neutral-to-ion flux ratio regime. Furthermore, the oxygen addition broadens the region over which the etching without roughening can be performed.

  20. Neutral gas temperature measurements of high-power-density fluorocarbon plasmas by fitting swan bands of C{sub 2} molecules

    SciTech Connect

    Bai Bo; Sawin, Herbert H.; Cruden, Brett A.

    2006-01-01

    The neutral gas temperature of fluorocarbon plasmas in a remote toroidal transformer-coupled source was measured to be greater than 5000 K, under the conditions of a power density greater than 15 W/cm{sup 3} and pressures above 2 torr. The rovibrational bands of C{sub 2} molecules (swan bands, d {sup 3}{pi}{sub g}{yields}a {sup 3}{pi}{sub u}) were fitted to obtain the rotational temperature that was assumed to equal the translational temperature. This rotational-translational temperature equilibrium assumption was supported by the comparison with the rotational temperature of second positive system of added N{sub 2}. For the same gas mixture, the neutral gas temperature is nearly a linear function of plasma power, since the conduction to chamber wall and convection are the major energy-loss processes, and they are both proportional to neutral gas temperature. The dependence of the neutral gas temperature on O{sub 2} flow rate and pressure can be well represented through the power dependence, under the condition of constant current operation. An Arrhenius type of dependence between the etching rate of oxide film and the neutral gas temperature is observed, maybe indicating the importance of the pyrolytic dissociation in the plasma formation process when the temperature is above 5000 K.

  1. Fluorocarbon assisted atomic layer etching of SiO2 and Si using cyclic Ar/C4F8 and Ar/CHF3 plasma

    SciTech Connect

    Metzler, Dominik; Li, Chen; Engelmann, Sebastian; Bruce, Robert L.; Joseph, Eric A.; Oehrlein, Gottlieb S.

    2015-11-11

    The need for atomic layer etching (ALE) is steadily increasing as smaller critical dimensions and pitches are required in device patterning. A flux-control based cyclic Ar/C4F8 ALE based on steady-state Ar plasma in conjunction with periodic, precise C4F8 injection and synchronized plasma-based low energy Ar+ ion bombardment has been established for SiO2.1 In this work, the cyclic process is further characterized and extended to ALE of silicon under similar process conditions. The use of CHF3 as a precursor is examined and compared to C4F8. CHF3 is shown to enable selective SiO2/Si etching using a fluorocarbon (FC) film build up. Other critical process parameters investigated are the FC film thickness deposited per cycle, the ion energy, and the etch step length. Etching behavior and mechanisms are studied using in situ real time ellipsometry and X-ray photoelectron spectroscopy. Silicon ALE shows less self-limitation than silicon oxide due to higher physical sputtering rates for the maximum ion energies used in this work, ranged from 20 to 30 eV. The surface chemistry is found to contain fluorinated silicon oxide during the etching of silicon. As a result, plasma parameters during ALE are studied using a Langmuir probe and establish the impact of precursor addition on plasma properties.

  2. 21 CFR 177.1380 - Fluorocarbon resins.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 1 CFR part 51. Copies may be obtained from the American Society for Testing and Materials, 1916 Race... practice, those food-contact articles intended for repeated use shall be thoroughly cleansed prior to...

  3. 21 CFR 177.1380 - Fluorocarbon resins.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 1 CFR part 51. Copies may be obtained from the American Society for Testing and Materials, 1916 Race... practice, those food-contact articles intended for repeated use shall be thoroughly cleansed prior to...

  4. 21 CFR 177.1380 - Fluorocarbon resins.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 1 CFR part 51. Copies may be obtained from the American Society for Testing and Materials, 1916 Race... practice, those food-contact articles intended for repeated use shall be thoroughly cleansed prior to...

  5. 21 CFR 177.1380 - Fluorocarbon resins.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Materials,” which is incorporated by reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies..., those food-contact articles intended for repeated use shall be thoroughly cleansed prior to their...

  6. 21 CFR 177.1380 - Fluorocarbon resins.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 1 CFR part 51. Copies may be obtained from the American Society for Testing and Materials, 1916 Race... practice, those food-contact articles intended for repeated use shall be thoroughly cleansed prior to...

  7. Role of surface temperature in fluorocarbon plasma-surface interactions

    SciTech Connect

    Nelson, Caleb T.; Overzet, Lawrence J.; Goeckner, Matthew J.

    2012-07-15

    This article examines plasma-surface reaction channels and the effect of surface temperature on the magnitude of those channels. Neutral species CF{sub 4}, C{sub 2}F{sub 6}, and C{sub 3}F{sub 8} are produced on surfaces. The magnitude of the production channel increases with surface temperature for all species, but favors higher mass species as the temperature is elevated. Additionally, the production rate of CF{sub 2} increases by a factor of 5 as the surface temperature is raised from 25 Degree-Sign C to 200 Degree-Sign C. Fluorine density, on the other hand, does not change as a function of either surface temperature or position outside of the plasma glow. This indicates that fluorine addition in the gas-phase is not a dominant reaction. Heating reactors can result in higher densities of depositing radical species, resulting in increased deposition rates on cooled substrates. Finally, the sticking probability of the depositing free radical species does not change as a function of surface temperature. Instead, the surface temperature acts together with an etchant species (possibly fluorine) to elevate desorption rates on that surface at temperatures lower than those required for unassisted thermal desorption.

  8. IR spectroscopy of gaseous fluorocarbon ions: The perfluoroethyl anion

    NASA Astrophysics Data System (ADS)

    Crestoni, Maria Elisa; Chiavarino, Barbara; Lemaire, Joel; Maitre, Philippe; Fornarini, Simonetta

    2012-04-01

    The first IR spectrum of a perfluorinated carbanion has been obtained in the gas phase by IRMPD spectroscopy. Quantum chemical calculations at the MP2/cc-pVTZ level were performed yielding the optimized geometries and IR spectra for a covalently bound C2F5- species and for conceivable loosely bound F-(C2F4) complexes. Both the computational results and the IR characterization point to a covalent structure for the assayed species in agreement with the reactivity pattern displayed with selected neutrals.

  9. Estimated historic emissions of fluorocarbons from the European Union

    NASA Astrophysics Data System (ADS)

    McCulloch, A.; Midgley, P. M.

    Emissions of chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs) and one hydrofluorocarbon (HFC-134a) from Europe have been estimated for the years 1986-1996 with a precision in most cases better than ±20%. During that period, sales of CFCs have reduced to virtually zero but they are still being emitted from the "bank" in use in equipment. These emissions are calculated to have fallen dramatically; however the largest releases are still of CFC-11, at 44,000 tonnes in 1996. Significant contributions to the total emission of ozone depleting substances from the European Union during 1996 were also made by HCFC-22 (35,000 tonnes) and CFC-12 (9000 tonnes); releases of other CFCs and HCFCs into the atmosphere from the EU are markedly less. On the other hand, emissions of HFC-134a (which is not an ozone depleting substance) would appear to be growing rapidly and could have reached 12,000 tonnes yr -1 in 1996. HFC-134a is a replacement for CFC-12, releases of which are calculated to have declined much more than the growth in HFC-134a. This leads to the conclusion that substitution of one by the other has been much less than 100% and is actually smaller than had been projected by market research in the early 1990s.

  10. Thermal Conductivity of Nonazeotropic Gaseous Mixtures of Fluorocarbon Refrigerants

    NASA Astrophysics Data System (ADS)

    Tanaka, Yoshiyuki; Ueno, Hiroshi; Kubota, Hironobu; Makita, Tadashi

    The thermal conductivity of four binary gaseous mixtures of R22 (CHCIF2) with R13(CClF3), R23(CHF3), R12(CCl2F2) and R114(CClF2·CClF2) has been measured at temperatures 298.15 and 323.15K under pressures from atmospheric to saturated pressures by a coaxial cylinder cell. The precision of the thermal conductivity obtained is within 2%. The thermal conductivity of mixtures increases with increasing temperature and pressure at a constant composition. The thermal conductivity in each mixture changes almost linearly with the concentration of R22 at a constant temperature and pressure, although the thermal conductivity at each composition is slightly larger than the calculated values by a simple molefraction average method. The experimental results were correlated with composition and pressure by empirical equations and compared with several kinds of prediction methods. The Brokaw's equation is found to reproduce the experimental data most successfully with a mean deviation of 0.7%.

  11. Fluorocarbon-modified water-soluble cellulose derivatives

    SciTech Connect

    Hwang, F.S.; Hogen-Esch, T.E. . Loker Hydrocarbon Research Inst. and Dept. of Chemistry)

    1993-06-07

    1,1-Dihydroperfluorobutyl,1,1-dihydroperfluorooctyl, and octyl derivatives of (hydroxyethyl)-cellulose (HEC) were prepared by reaction of the Na salt of HEC in aqueous isopropyl alcohol with 1,1-dihydroperfluorobutyl or octyl p-toluenesulfonate (4 or 5), with 1,1-dihydroperfluorobutyl or octyl glycidyl ether or (8 or 9), and with octyl glycidyl ether (12). The degrees of substitution of HEC were determined using [sup 19]FNMR and varied between 0.023 and 1.20 mol % of anhydroglucose units (AGU). The HEC derivatives modified with 4, 5, and 8 were sparingly soluble or insoluble, and their aqueous solutions were generally low in viscosity. In contrast solutions of HEC modified with 9 did have significantly enhanced viscosities with respect to unmodified HEC or compared to HEC modified with the octyl glycidyl ether, having the same chain length as 9. The Brookfield viscosity plotted against perfluorocarbon content of aqueous solutions of HEC modified with 9 was shown to go through a maximum at about 0.42 mol % (0.92 wt %) with respect to AGU's. The solutions of this and similar polymers were shown to be highly pseudoplastic. Furthermore, increases in viscosity were observed upon addition to NaCl. These observations are consistent with the very strong intermolecular hydrophobic association of the perfluorocarbon groups.

  12. Photoluminescence of silicone oil treated by fluorocarbon plasma

    NASA Astrophysics Data System (ADS)

    Chen, Tian; Ye, Chao; Yuan, Ying; Deng, Yan-Hong; Ge, Shui-Bin; Xu, Yi-Jun; Ning, Zhao-Yuan; Pan, Xiao-Ping; Wang, Zhen-Ming

    2012-09-01

    We investigated photoluminescence characteristics of silicone oils treated by C2F6 and CHF3 plasma. The silicone oil treated by the C2F6 plasma emitted a white light mainly composed of 415 nm, 469 nm, and 554 nm emissions, while that treated by the CHF3 plasma emitted a pink light (415 nm). Fourier transformed infrared spectroscopy and Raman spectroscopy studies showed that the photoluminescence was correlated with the SiC bond, the carbon-related defects and the oxygen vacancies. It was suggested that the light emitting at 554 nm was related to the SiC bond and the carbon-related defects, while the pink emission at 415 nm was related to the oxygen vacancies.

  13. Total cross section of electron scattering by fluorocarbon molecules

    NASA Astrophysics Data System (ADS)

    Yamada, T.; Ushiroda, S.; Kondo, Y.

    2008-12-01

    A compact linear electron transmission apparatus was used for the measurement of the total electron scattering cross section at 4-500 eV. Total cross sections of chlorofluorocarbon (CCl2F2), hydrochlorofluorocarbon (CHClF2), perfluoropropane (C3F8), perfluoro-n-pentane (C5F12), perfluoro-n-hexane (C6F14) and perfluoro-n-octane (C8F18) were obtained experimentally and compared with the values obtained from a theoretical calculation and semi-empirical model calculation.

  14. Chemistry of the global troposphere - Fluorocarbons as tracers of air motion

    NASA Technical Reports Server (NTRS)

    Prather, Michael; Russell, Gary; Rind, David; Mcelroy, Michael; Wofsy, Steven

    1987-01-01

    Winds and convective mixing from a general circulation model of the atmosphere have been applied in a chemical tracer model (CTM) to simulate the global distribution and temporal variability of chlorofluorocarbons (CFCs). The seasonal cycle in moist convection, with maximum activity over continents in summer, leads to an annual cycle in the surface concentration of CFCs. Emissions are retained in the lowest levels of the atmosphere during winter, and surface concentrations peak near sources. In this season, CFCs from European sources are carried by low-level winds into the Arctic. During summer, vertical exchange is more efficient, and pollutants are transported more rapidly to the middle atmosphere. Consequently, concentrations of CFCs during summer are relatively low near the surface and elevated in the middle troposphere. Time series analysis of data from Adrigole, Ireland, indicates that the model accurately simulates long-range transport of air pollution. The model reproduces global distributions and trends for CFC-11 and CFC-12 observed by the ALE experiment; however, subgrid diffusion must be introduced into the model in order to reproduce the observed interhemispheric gradient. Interhemispheric exchange occurs mainly in the upper tropical troposphere, producing a profile which increases with altitude in the Southern Hemisphere, in agreement with observations. The distribution of CFCs is such that it is necessary to apply important corrections to observations at surface stations in order to derive global distributions.

  15. An on-line acoustic fluorocarbon coolant mixture analyzer for the ATLAS silicon tracker

    SciTech Connect

    Bates, R.; Battistin, M.; Berry, S.; Bitadze, A.; Bonneau, P.; Bousson, N.; Boyd, G.; Botelho-Direito, J.; DiGirolamo, B.; Doubek, M.; Egorov, K.; Godlewski, J.; Hallewell, G.; Katunin, S.; Mathieu, M.; McMahon, S.; Nagai, K.; Perez-Rodriguez, E.; Rozanov, A.; Vacek, V.; Vitek, M.

    2011-07-01

    The ATLAS silicon tracker community foresees an upgrade from the present octafluoro-propane (C{sub 3}F{sub 8}) evaporative cooling fluid - to a composite fluid with a probable 10-20% admixture of hexafluoro-ethane (C{sub 2}F{sub 6}). Such a fluid will allow a lower evaporation temperature and will afford the tracker silicon substrates a better safety margin against leakage current-induced thermal runaway caused by cumulative radiation damage as the luminosity profile at the CERN Large Hadron Collider increases. Central to the use of this new fluid is a new custom-developed speed-of-sound instrument for continuous real-time measurement of the C{sub 3}F{sub 8}/C{sub 2}F{sub 6} mixture ratio and flow. An acoustic vapour mixture analyzer/flow meter with new custom electronics allowing ultrasonic frequency transmission through gas mixtures has been developed for this application. Synchronous with the emission of an ultrasound 'chirp' from an acoustic transmitter, a fast readout clock (40 MHz) is started. The clock is stopped on receipt of an above threshold sound pulse at the receiver. Sound is alternately transmitted parallel and anti-parallel with the vapour flow for volume flow measurement from transducers that can serve as acoustic transmitters or receivers. In the development version, continuous real-time measurement of C{sub 3}F{sub 8}/C{sub 2}F{sub 6} flow and calculation of the mixture ratio is performed within a graphical user interface developed in PVSS-II, the Supervisory, Control and Data Acquisition standard chosen for LHC and its experiments at CERN. The described instrument has numerous potential applications - including refrigerant leak detection, the analysis of hydrocarbons, vapour mixtures for semiconductor manufacture and anesthetic gas mixtures. (authors)

  16. Thermally robust and porous noncovalent organic framework with high affinity for fluorocarbons and CFCs

    NASA Astrophysics Data System (ADS)

    Chen, Teng-Hao; Popov, Ilya; Kaveevivitchai, Watchareeya; Chuang, Yu-Chun; Chen, Yu-Sheng; Daugulis, Olafs; Jacobson, Allan J.; Miljanić, Ognjen Š.

    2014-10-01

    Metal-organic and covalent organic frameworks are porous materials characterized by outstanding thermal stability, high porosities and modular synthesis. Their repeating structures offer a great degree of control over pore sizes, dimensions and surface properties. Similarly precise engineering at the nanoscale is difficult to achieve with discrete molecules, since they rarely crystallize as porous structures. Here we report a small organic molecule that organizes into a noncovalent organic framework with large empty pores. This structure is held together by a combination of [N-H···N] hydrogen bonds between the terminal pyrazole rings and [π···π] stacking between the electron-rich pyrazoles and electron-poor tetrafluorobenzenes. Such a synergistic arrangement makes this structure stable to at least 250 °C and porous, with an accessible surface area of 1,159 m2 g-1. Crystals of this framework adsorb hydrocarbons, CFCs and fluorocarbons—the latter two being ozone-depleting substances and potent greenhouse species—with weight capacities of up to 75%.

  17. Regarding the effect that different hydrocarbon/fluorocarbon surfactant mixtures have on their complexation with HSA.

    PubMed

    Blanco, Elena; Messina, Paula; Ruso, Juan M; Prieto, Gerardo; Sarmiento, Flix

    2006-06-15

    The complexations between human serum albumin (HSA) and the sodium perfluorooctanoate/sodium octanoate and sodium perfluorooctanoate/sodium dodecanoate systems have been studied by a combination of electrical conductivity, ion-selective electrode, electrophoresis, and spectroscopy measurements. The binary mixtures of the surfactants deviated slightly from ideality. Binding plots revealed the existence of two specific binding sites, the first site being more accessible than the second. Positive cooperative binding has been found, thus revealing the importance of the hydrophobic interactions in both kinds of surfactants. The Gibbs energies of binding per mole of surfactant (DeltaG(nu)) were calculated from the Wyman binding potential where, on the basis of the elevated number of binding sites, a statistical contribution has been included. Initially these energies are large and negative, gradually decreasing as saturation is approached. Changes in the slope of Gibbs energies have been identified with the saturation of the first binding set. These facts denote that the surfactants under study have different favorite adsorption sites along the protein and that the adsorption process of perfluorooctanoate is more closely followed by dodecanoate than by octanoate. Finally, electrophoresis and spectroscopy measurements suggest induced conformational changes on HSA depending on the surfactant mixture as well as the mixed ratio. PMID:16771408

  18. Synthesis and biological screening by novel hybrid fluorocarbon hydrocarbon compounds for use as artificial blood substitutes

    NASA Technical Reports Server (NTRS)

    Moacanin, J.; Scherer, K.; Toronto, A.; Lawson, D.; Terranova, T.; Yavrouian, A.; Astle, L.; Harvey, S.; Kaaelble, D. H.

    1979-01-01

    A series of hybrid fluorochemicals of general structure R(1)R(2)R(3)CR(4) was prepared where the R(i)'s (i=1,2,3) is a saturated fluoroalkyl group of formula C sub N F sub 2n+1, and R(4) is an alkyl group C sub n H sub 2n+1 or a related moiety containing amino, ether, or ester functions but no CF bonds. Compounds of this class containing approximately eight to twenty carbons total have physical properties suitable for use as the oxygen carrying phase of fluorochemical emulsion artificial blood. The chemical synthesis, and physical and biological testing of pure single isomers of the proposed artificial blood candidate compounds are included. Significant results are given.

  19. 40 CFR Appendix A to Subpart F of... - Specifications for Fluorocarbon and Other Refrigerants

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... existing refrigeration and air-conditioning products as required under 40 CFR part 82. 1.1.1Intent. This... PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) PROTECTION OF STRATOSPHERIC OZONE Recycling...

  20. 40 CFR Appendix A to Subpart F of... - Specifications for Fluorocarbon and Other Refrigerants

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... existing refrigeration and air-conditioning products as required under 40 CFR part 82. 1.1.1Intent. This... PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) PROTECTION OF STRATOSPHERIC OZONE Recycling...

  1. 40 CFR Appendix A to Subpart F of... - Specifications for Fluorocarbon and Other Refrigerants

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... existing refrigeration and air-conditioning products as required under 40 CFR part 82. 1.1.1Intent. This... PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) PROTECTION OF STRATOSPHERIC OZONE Recycling...

  2. 40 CFR Appendix A to Subpart F of... - Specifications for Fluorocarbon and Other Refrigerants

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... existing refrigeration and air-conditioning products as required under 40 CFR part 82. 1.1.1Intent. This... PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) PROTECTION OF STRATOSPHERIC OZONE Recycling...

  3. 40 CFR Appendix A to Subpart F of... - Specifications for Fluorocarbon and Other Refrigerants

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... existing refrigeration and air-conditioning products as required under 40 CFR part 82. 1.1.1Intent. This... PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) PROTECTION OF STRATOSPHERIC OZONE Recycling...

  4. ULTRASONIC CLEANING AS A REPLACEMENT FOR A CHLORO- FLUOROCARBON-BASED SYSTEM

    EPA Science Inventory

    This report describes the technical and economic evaluation of the replacement of a vapor degreasing system with an ultrasonic cleaning system to clean stainless steel components. Heated inorganic water-based cleaning fluid was utilized in lieu of a chlorofluorocarbon (CFC, freon...

  5. Short- and long-term releases of fluorocarbons from disposal of polyurethane foam waste.

    PubMed

    Kjeldsen, Peter; Scheutz, Charlotte

    2003-11-01

    Several halocarbons having very high global warming or ozone depletion potentials have been used as a blowing agent (BA) for insulation foam in home appliances, such as refrigerators and freezers. Many appliances are shredded after the end of their useful life. Release experiments carried out in the laboratory on insulation foam blown with the blowing agents CFC-11, HCFC-141b, HCF-134fa, and HFC-245fa revealed that not all blowing agents are released during a 6-week period following the shredding process. The experiments confirmed the hypothesis that the release could be divided into three segments: By shredding foam panels, a proportion of the closed cells is either split or damaged to a degree allowing for a sudden release of the contained atmosphere in the cell (the instantaneous release). Cells adjacent to the cut surface may be only slightly damaged by tiny cracks or holes allowing a relative slow release of the BA to the surroundings (the short-term release). A significant portion of the cells in the foam particle will be unaffected and only allows release governed by slow diffusion through the PUR cell wall (the long-term release). The magnitude of the releases is for all three types highly dependent on how fine the foam is shredded. The residual blowing agent remaining after the 6-week period may be very slowly released if the integrity of the foam particles with respect to diffusion properties is kept after disposal of the foam waste on landfills. It is shown by setting up a national model simulating the BA releases following decommissioning of used domestic refrigerators/freezers in the United States that the release patterns are highly dependent on how the appliances are shredded. PMID:14620840

  6. Sources of hydrochlorofluorocarbons, hydrofluorocarbons and fluorocarbons and their potential emissions during the next twenty five years.

    PubMed

    McCulloch, A

    1994-05-01

    In common with CFCs, the classes of compounds in the title have wholly anthropogenic sources. CFCs are used for refrigeration, air-conditioning, foam blowing, solvent cleaning and propelling aerosols and, in each case, equipment has been designed to make the most efficient use of the properties of individual compounds. There is little scope for substitution, even between CFCs. The potential for replacement of these historic uses by substitute technologies - ammonia, hydrocarbons, carbon dioxide and HCFCs, HFCs and FCs -is examined. It is shown that the quantities required are influenced as much by improvements to containment as they are by the primary demands from society.Based on analysis of the historic data; the declared manufacturing capacities, and the anticipated effects of international controls, the potential production and emissions of the principal HCFCs and HFCs are calculated for the next twenty five years. While consumption of HCFCs will fall nearly to zero, it would appear that demand for HFC-134a could double, from approximately 150,000 to 300,000 tonnes/year between 1995 and 2020. Over the same timescale demand for HFC-32 could rise to 90,000 tonnes/year. The potential future emissions of other HCFCs, HFCs and FCs which are expected to be used less widely, or for which there is no current consumption base from which to make meaningful extrapolations, are also discussed. PMID:24213902

  7. INDUSTRIAL PROCESS PROFILES FOR ENVIRONMENTAL USE: CHAPTER 16. THE FLUOROCARBON-HYDROGEN FLORIDE INDUSTRY

    EPA Science Inventory

    The catalog of Industrial Process Profiles for Environmental Use was developed as an aid in defining the environmental impacts of industrial activity in the United States. Entries for each industry are in consistent format and form separate chapters of the study. The materials of...

  8. Interlaboratory comparison of fluorocarbons-11, -12, methylchloroform and nitrous oxide measurements

    NASA Technical Reports Server (NTRS)

    Rasmussen, R. A.; Khalil, M. A. K.

    1981-01-01

    Measurements conducted by 19 participating laboratories were considered in the reported interlaboratory comparison study. The results show that there is considerable disagreement among laboratories regarding the absolute concentrations of all four trace gases (CCl3F, CCl2F2, H3CCl3, N2O). The magnitude of this disagreement is discussed. Laboratories in Group II showed considerable disagreement among themselves. Their results were scattered within large intervals of concentration. Laboratories in Group I (using common standards) were in excellent (+ or - 5%) agreement among themselves. A systematic disagreement was noted between Groups I and II laboratories. Generally, the mean values of concentrations determined from the measurements of Group II laboratories were lower than the mean values reported by Group I laboratories.

  9. Electron attachment to C{sub 2} fluorocarbon radicals at high temperature

    SciTech Connect

    Shuman, Nicholas S.; Miller, Thomas M.; Viggiano, Albert A.

    2013-11-14

    Thermal electron attachment to the radical species C{sub 2}F{sub 3} and C{sub 2}F{sub 5} has been studied over the temperature range 300–890 K using the Variable Electron and Neutral Density Attachment Mass Spectrometry technique. Both radicals exclusively undergo dissociative attachment to yield F{sup −}. The rate constant for C{sub 2}F{sub 5} shows little dependence over the temperature range, remaining ∼4 × 10{sup −9} cm{sup 3} s{sup −1}. The rate constant for C{sub 2}F{sub 3} attachment rises steeply with temperature from 3 × 10{sup −11} cm{sup 3} s{sup −1} at 300 K to 1 × 10{sup −9} cm{sup 3} s{sup −1} at 890 K. The behaviors of both species at high temperature are in agreement with extrapolations previously made from data below 600 K using a recently developed kinetic modeling approach. Measurements were also made on C{sub 2}F{sub 3}Br and C{sub 2}F{sub 5}Br (used in this work as precursors to the radicals) over the same temperature range, and, for C{sub 2}F{sub 5}Br as a function of electron temperature. The attachment rate constants to both species rise with temperature following Arrhenius behavior. The attachment rate constant to C{sub 2}F{sub 5}Br falls with increasing electron temperature, in agreement with the kinetic modeling. The current data fall in line with past predictions of the kinetic modeling approach, again showing the utility of this simplified approach.

  10. New fluorocarbon elastomers for seals for geothermal and other aggressive environments

    SciTech Connect

    Dumitru, Earl T.; Lagow, R.J.; Kukacka L.E.

    1982-10-08

    Geothermal brines at 600 F which contain metallic salts, H{sub 2}S, and hydrocarbons quickly degrade conventional hydrocarbon elastomers, and hydrolyse crosslinks. Carbon-carbon and carbon-fluorine bonds are expected to be superior, but no such elastomer is now commercially available. We have prepared crosslinked, perfluorocarbon elastomers by radiation crosslinking VDFHFP and TFEP (alternating) copolymers in film and sheet form, and then converting C-H bonds to C-F bonds with elemental Fluorine gas. EPLM elastomers became brittle on fluorination. The best products exceeded 100 days survival at 300 C in simulated geothermal brine. Tensile, elongation, solvent swelling, and TCA methods were used to study the products.

  11. New fluorocarbon elastomers for seals for geothermal and other aggressive environments. Final report

    SciTech Connect

    Lagow, R.J.

    1982-12-01

    Saturated ethyllenic elastomers having a range of methyl group substitution, and a range of partial fluorine substitution were screened. Elastomers based on vinylidene fluoride hexafluoropropylene (VDFHFP) and those based on tetrafluoroethylenepropylene (TFEP) (alternating) were successfully cross-linked by electron-beam radiation and fluorinated to yield elastomeric products, but those based on ethylene-propylene-diene (EPDM) elastomer became brittle after fluorination. The best products were evaluated using tensile strength, elongation at break, solvent swelling, thermogravimetric analysis and infrared. A wide range of carbon-black filled compositions using the TFEP elastomer were cross-linked. The compositions were then fluorinated at or near room temperature for extended periods of time. After fluorination the samples were subjected to geothermal brine at 300/sup 0/C. The best carbon-black filled composition again lasted at least 100 days in the geothermal brine. This filler-elastomer composition was chosen for use in the production of 0-rings. The 0-rings were produced by compression molding using a 30 ton hydraulic press. Various sizes of 0-rings were produced ranging fro 0.8 to 2.0 inches in diameter and from 1/16 to 3/16 inches in width. The final 0-rings were cross-linked at 40 Mrad and fluorinated under the optimized conditions developed for the samples.

  12. Double emulsions based on silicone-fluorocarbon-water and their skin penetration.

    PubMed

    Mahrhauser, Denise-Silvia; Fischer, Claudia; Valenta, Claudia

    2016-02-10

    Double emulsions have significant potential in pharmacy and cosmetics due to the feasibility of combining incompatible substances in one product and the protection of sensitive compounds by incorporating them into their innermost phase. However, a major drawback of double emulsions is their thermodynamic instability and their strong tendency to coalesce. In the present study, the physicochemical stability, the skin permeation and the skin penetration potential of modified semi-solid double emulsions was investigated. The double emulsions were prepared of the cosmetically applied perfluoropolyethers Fomblin(®) HC/04 or Fomblin(®) HC-OH, silicone, carbomer and water. Measurement of the droplet size and examination of the microscopic images confirmed their physicochemical stability over the observation period of eight weeks. Franz-type diffusion cell experiments revealed no increase in curcumin permeation due to the employed perfluoropolyethers compared to the respective control formulations. The formulations used as control were O/W macroemulsions with or without a Polysorbate 80/Sorbitane monooleate 80 surfactant combination. Likewise, tape stripping studies showed no penetration enhancing effect of the employed perfluoropolyethers which is desirable as both perfluoropolyethers are commonly applied components in human personal-care products. PMID:26688033

  13. Preparation, characterization, physical testing and performance of fluorocarbon membranes and separators

    NASA Technical Reports Server (NTRS)

    Lagow, R. J.; Dumitru, E. T.

    1982-01-01

    The direct fluorination method of converting carefully selected hydrocarbon substrates to fluorinated membranes was successfully applied to produce promising, novel membranes for electrochemical devices. A family of polymer blends was identified which permits wide latitude in the concentration of both crosslinks and carboxyl groups in hydrocarbon membranes. These membranes were successfully fluorinated and are potentially competitive with commercial membranes in performance, and potentially much cheaper in price.

  14. Effects of water-soluble spacers on the hydrophobic association of fluorocarbon modified polyacrylamide

    SciTech Connect

    Hwang, F.S.; Hogen-Esch, T.E.

    1993-12-31

    A number of acrylamide-acrylate copolymers were synthesized in which the acrylate (CH{sub 2}=CHCOO(CH{sub 2}CH{sub 2}O){sub n}R{sub t}) is hydrophobic on account of the presence of a 1,1-dihydroperfluorooctyl group (R{sub F}) connected to the acrylate via a-(CH{sub 2}CH{sub 2}O){sub n} hydrophobic spacer (n=0-3). Copolymerization of the two comonomers was carried out in aqueous media in the presence of potassium perfluoro octanoate and acetone (10 vol%) and was initiated by sodium metabisufite and ammonium persulfate at 50{degrees}C. The Brookfield viscosities measured at 0.4 sec{sup {minus}1} as a function of comonomer molar content gave bell-shaped curves having maxima at .10-.15 mole% comonomer except for the comonomer without hydrophilic spacer (n=0) where the maximum is at .60 mole%. The viscosity maxima of the copolymers are quite dependent on the value of n giving the highest viscosities at n=3 (45,000 cp) that decreases value of n. The increased effectiveness of the longer spacers is attributed to decreased intermolecular excluded volume effects in the formation of the polymer assemblies.

  15. Decomposition experiment of hydro-fluorocarbon gas by pulsed TEA CO2 laser

    NASA Astrophysics Data System (ADS)

    Maeno, Kazuo; Udagawa, Shinsuke; Toyada, Kazuhiro

    2005-03-01

    This paper deals with a trial experiment of decomposition of environmental gas R-12 by the pulsed TEA CO2 laser. Nowadays refrigerant R-12 and other hydro-chlorofluorocarbon gases are strongly prohibited to produce, as these gases have both strong ozone-depleting effects and green-house effects. The gases of already produced by huge amount should be decomposed as fast as possible by suitable technical methods. Along with the conventional kiln furnace of cement, arc discharge and the HG discharge are good methods for the freon decomposition. Both methods, however, have the weakness of electrode damages (arcing) or low-pressure operation (HF discharge). High power CO2 laser seems to have good properties for such decomposition with favorable wavelength for the absorption. In our small-scale experiment of gas decomposition a pulsed TEA CO2 laser of several joules is utilized to produce the plasma in R-12 flow channel of glass tube. The withdrawal of decomposed gases is performed by Ca alkalized water. The deposit mass is measured, and powder X-ray diffraction measurement is carried out on the deposit powder. The possibility of our laser gas decomposition is discussed.

  16. Perfluoroalklylated phospholipids as surfactants and co-surfactants forinjectable fluorocarbon emulsions.

    PubMed

    Santaella, C; Vierling, P; Riess, J G

    1992-01-01

    Highly fluorinated phospholipids were investigated as sole surfactant, and as co-surfactant with egg yolk phospholipids (EYP), in the formulation of 50% and 100% w/v perfluorodecalin emulsions. The surfactant's capability to stabilize such emulsions improves with the length of the perfluoroalklylated tail and with the increase of its relative weight in the hydrophobic chain. As sole surfactant, 2, which has the longest fluorinated tail has the highest efficacy. As co-surfactant with EYP, a strong stabilizing effect is found when the total hydrophobic chain length is adjusted to the EYP membrane's thickness, which is the case of 1. Dispersions of the F-phospholipids do not modify cell growth and viability and show no hemolytic activity on human red blood cells at concentrations in the 60-100g/L range. Acute toxicity tests in mice indicate - i.v. DL50 greater than 2.75 g/Kg body wt. PMID:1391518

  17. Galvanic cell having a saturated fluorocarbon plasma-treated sealing gasket

    SciTech Connect

    Yasuda, H.; van Lier, J. A.

    1985-02-26

    Galvanic cells employing compressible gaskets having at least a portion of the sealing areas of such gaskets coated with plasma deposited fluorine atoms demonstrate increased resistance to electrolyte leakage.

  18. An assessment of potential impact of alternative fluorocarbons on tropospheric ozone

    NASA Technical Reports Server (NTRS)

    Niki, Hiromi

    1990-01-01

    While the chlorofuorocarbons (CFCs) such as CFC-11 (CFCl3) and CFC-12 (CF2Cl2) are chemically inert in the troposphere, the hydrogen-containing halocarbons being considered as their replacements can, to a large extent, be removed in the troposphere by the HO radical. These alternative halocarbons include the hydrochlorofluorocarbons (HCFCs) 123 (CF3CHCl2), 141b (CFCl2CH3), 142b (CF2ClCH3), 22 (CHF2Cl), and 124 (CF3CHFCl) and the hydrofluorocarbons (HCFs) 134a (CF3CH2F), 152a (CHF2CH3) and 125 (CF3CHF2). Listed are the rate constants (k) for the HO radical reaction of these compounds and their estimated chemical lifetimes in the troposphere. In this table, values of the lifetimes of these selected HCFCs and HCFs are seen to vary by more than a factor of more than ten ranging from 1.6 years for HFC 152a and HCFC 125 to as long as 28 years for HFC 125. Clearly, from the standpoint of avoiding or minimizing impact on stratospheric O3, those halocarbons with short tropospheric lifetimes are the desirable alternates. However, potential environmental consequences of their degradation in the troposphere should be assessed and taken into account in the selection process.

  19. Fluorocarbon liner protected with chemical resistant masonry solves tough corrosion problem

    SciTech Connect

    Heffner, D.

    1997-02-01

    At a major pigment manufacturer`s plant, a kiln produces SO{sub 2}-SO{sub 3} process gas containing 90% SO{sub 2} used in sulfuric acid production. The towers where the sulfuric acid is produced follow an intermediate stage in the production of iron-based pigments. The lead-lined towers that had lasted more than five years began to leak after two years. Once the liner develops a pinhole leak, acid eats through the carbon steel substrate within a few days. A composite membrane was selected consisting of PVDF resin reinforced with woven cloth for improved physical properties. This was applied over the entire surface of the scrubber tower, including inlets, outlets, and metal flanges. The laminate was applied by a multi-coat wet lay-up process to a nominal thickness of 40 mil (1 mm), oven baked after each coat.

  20. Comparison of TEWI for fluorocarbon alternative refrigerants and technologies in residential heat pumps and air conditioners

    SciTech Connect

    Sand, J.R.; Fischer, S.K.; Baxter, V.D.

    1999-07-01

    A study was conducted to examine the total equivalent warming impacts (TEWI) of unitary residential and commercial space conditioning equipment in North America, Europe, and Japan using refrigerants R-407C, R-410A, and R-290 and alternative heating/cooling technologies. Assumptions and results of this study are presented for US residential applications. Alternative systems are compared with the TEWI of conventional R-22 based vapor compression systems under the same operating conditions. The analysis for North America includes low- and medium-efficiency electric heat pumps and high-efficiency air-to-air and geothermal heat pumps. Alternative space conditioning technologies, such as electric resistance heat, a gas furnace/central air conditioner combination, a gas engine-driven heat pump, and a prototype gas-fired absorption heat pump, are included for residential TEWI comparisons in three US cities with a range of heating and cooling loads. The effects of improving seasonal efficiencies on TEWI are shown, as well as the consequences of replacing R-22 with alternative refrigerants. TEWI results from previous reports, and those presented here show that the direct global warming potential (GWP) of the refrigerant used for residential heat pump applications contributes less than 7% to the total TEWI for these products and that the direct GWP of the refrigerant is less important than the overall efficiency of the unitary system. Clearly, any refrigerant or refrigerant blend proposed as an alternative for R-22 must provide good cycle efficiency in addition to acceptable environmental and operational qualities to be seriously considered in unitary equipment applications.

  1. Chemistry of the global troposphere: Fluorocarbons as tracers of air motion

    NASA Astrophysics Data System (ADS)

    Prather, Michael; McElroy, Michael; Wofsy, Steven; Russell, Gary; Rind, David

    1987-06-01

    Winds and convective mixing from a general circulation model of the atmosphere have been applied in a chemical tracer model (CTM) to simulate the global distribution and temporal variability of chlorofluorocarbons (CFCs). The seasonal cycle in moist convection, with maximum activity over continents in summer, leads to an annual cycle in the surface concentration of CFCs. Emissions are retained in the lowest levels of the atmosphere during winter, and surface concentrations peak near sources. In this season, CFCs from European sources are carried by low-level winds into the Arctic. During summer, vertical exchange is more efficient, and pollutants are transported more rapidly to the middle atmosphere. Consequently, concentrations of CFCs during summer are relatively low near the surface and elevated in the middle troposphere. Time series analysis of data from Adrigole, Ireland, indicates that the model accurately simulates long-range transport of air pollution. The model reproduces global distributions and trends for CFC-11 and CFC-12 observed by the ALE experiment; however, subgrid diffusion must be introduced into the model in order to reproduce the observed interhemispheric gradient. Interhemispheric exchange occurs mainly in the upper tropical troposphere, producing a profile which increases with altitude in the southern hemisphere, in agreement with observations. The distribution of CFCs is such that it is necessary to apply important corrections to observations at surface stations in order to derive global distributions.

  2. Proceedings of the 1993 non-fluorocarbon insulation, refrigeration and air conditioning technology workshop

    SciTech Connect

    Not Available

    1994-09-01

    Sessions included: HFC blown polyurethanes, carbon dioxide blown foam and extruded polystyrenes, plastic foam insulations, evacuated panel insulation, refrigeration and air conditioning, absorption and adsorption and stirling cycle refrigeration, innovative cooling technologies, and natural refrigerants. Selected papers have been indexed separately for inclusion in the Energy Science and Technology Database.

  3. Tropospheric reactions of the haloalkyl radicals formed from hydroxyl radical reaction with a series of alternative fluorocarbons

    NASA Technical Reports Server (NTRS)

    Atkinson, Roger

    1990-01-01

    In the present assessment, the hydrogen containing halocarbons being considered as alternatives to the the presently used chlorofluorocarbons are the hydrochlorofluorocarbons (HCFCs) 123 (CF3CHCl2), 141b (CFCl2CH3), 142b (CF2ClCH3), 22 (CHF2Cl) and 124 (CF3CHFCl) and the hydrofluorocarbons (HFCs) 134a (CF3CH2F), 152a (CHF2CH3) and 125 (CF3CHF2). All of these HCFCs and HFCs will react with the hydroxyl (OH) radical in the troposphere, giving rise to haloalkyl radicals which then undergo a complex series of reactions in the troposphere. These reactions of the haloalkyl radicals formed from the initial OH radical reactions with the HCFCs and HFCs under tropospheric conditions are the focus here.

  4. Nanostructure Imaging Mass Spectrometry: The Role of Fluorocarbons in Metabolite Analysis and the Road to Yoctomole Level Sensitivity

    PubMed Central

    Kurczy, Michael E.; Northen, Trent R.; Trauger, Sunia A.; Siuzdak, Gary

    2016-01-01

    Nanostructure Imaging mass spectrometry (NIMS) has become an effective technology for generating ions in the gas phase, providing high sensitivity and imaging capabilities on small molecules, metabolites, drugs, and drug metabolites. Specifically, laser desorption from the nanostructure surfaces results in efficient energy transfer, low background chemical noise, and the nondestructive release of analyte ions into the gas phase. The modification of nanostructured surfaces with fluorous compounds, either covalent or non-covalent, has played an important role in gaining high efficiency/sensitivity by facilitating analyte desorption from the non-adhesive surfaces, and minimizing the amount of laser energy required. In addition, the hydrophobic fluorinated nanostructure surfaces have aided in concentrating deposited samples into fine micrometer sized spots, a feature that further facilitates efficient desorption/ionization. These fluorous nanostructured surfaces have opened up NIMS to very broad applications including enzyme activity assays and imaging, providing low background, efficient energy transfer, nondestructive analyte ion generation, super-hydrophobic surfaces, and ultra-high detection sensitivity. PMID:25361674

  5. Post-Flight Analysis of Selected Fluorocarbon and Other Thin Film Polymer Specimens Flown on MISSE-5

    NASA Technical Reports Server (NTRS)

    DeGroh, Kim; Finckenor, Miria; Minton, Tim; Brunsvold, Amy; Pippin, Gary

    2007-01-01

    Twenty thin film specimens were flown on M1SSE-5 as a cooperative effort between several organizations. This presentation will report results of initial inspections and post-flight measurements of the optical properties and recession of these materials due to the approx.13 month exposure period on the exterior of the International Space Station. These specimens were located on the "anti-solar" side of the MISSE-5 container and received a low number of Equivalent Sun Hours of solar UV exposure. Profilometry and/or ATF measurements will be conducted to determine thickness changes and atomic oxygen-induced recession rates Six of the specimens were covered with thin Kapton films, 0.1 and 0.3 mil in thickness. The 0.1 mil Kapton was almost completely eroded, suggesting that the atomic oxygen fluence is <8 x 10(exp 19) atoms/sq cm, similar to levels experienced during Space Shuttle materials experiments in the 1980's and 1990's. A comparison of results from MISSE-5 and Space Shuttle experiments will be included for those materials common to both the short and long-term exposures.

  6. Development of atmospheric characteristics of chlorine-free alternative fluorocarbons. Report on R-134a and E-143a

    SciTech Connect

    Orkin, V.L.; Khamaganov, V.G.; Guschin, A.G.; Kasimovskaya, E.E.; Larin, I.K.

    1993-04-01

    Rate constants have been measured for the gas phase reaction of OH radicals with 1,1,1,2-tetrafluoroethane R-134a (CH{sub 2}F-CF{sub 3}) and methyl trifluoromethyl ether E-143a (CH{sub 3}-O-CF{sub 3}) over the temperature range 298--460 K. Arrhenius expressions were derived for atmospheric modeling. The infrared absorption cross-sections for R-134a and E-143a have been measured in the region from 400 to 1600 cm{sup {minus}1} and the integrated band strengths have been calculated. The atmospheric lifetimes R-134a and E-143a have been estimated to be 11.6 years and 4.1 years respectively. Global warming potentials have been estimated over time horizons of 20, 50, 100, 200, and 500 years.

  7. Effects of water-soluble spacers on the hydrophobic association of fluorocarbon-modified poly(acrylamide)

    SciTech Connect

    Hwang, F.S.; Hogen-Esch, T.E.

    1995-04-24

    A number of acrylamide-acrylate copolymers were synthesized in which the acrylate (CH{sub 2}{double_bond}CHCOO(CH{sub 2}CH{sub 2}O){sub n}R) is hydrophobic on account of the presence of a 1,1-dihydroperfluorooctyl group or a dodecyl group connected to the acrylate via a {minus}(CH{sub 2}CH{sub 2}O){sub n} hydrophilic spacer (n = 0--3). Copolymerization of these monomers was initiated by sodium metabisulfite and ammonium persulfate at 60 C in aqueous media in the presence of surfactants and acetone. The low shear viscosities of 0.5 wt % solutions of these copolymers as a function of comonomer molar content gave bell-shaped curves having maxima at 0.10--0.60 mol % comonomer, consistent with competitive inter- and intramolecular hydrophobic association. The copolymers having perfluorocarbon pendent groups gave higher viscosities at lower comonomer content. Furthermore, for both the hydrocarbon- and perfluorocarbon-containing copolymers the viscosities increased, and the comonomer content at the viscosity maximum decreased, with increasing spacer length. The increased effectiveness of the longer spacers is attributed to entropy effects in the formation of polymer assemblies.

  8. An assessment of potential degradation products in the gas-phase reactions of alternative fluorocarbons in the troposphere

    NASA Technical Reports Server (NTRS)

    Niki, Hiromi

    1990-01-01

    Tropospheric chemical transformations of alternative hydrofluorocarbons (HCF's) and hydrochlorofluorocarbons (HCFC's) are governed by hydroxyl radical initiated oxidation processes, which are likely to be analogous to those known for alkanes and chloroalkanes. A schematic diagram is used to illustrate plausible reaction mechanisms for their atmospheric degradation, where R, R', and R'' denote the F- and/or Cl-substituted alkyl groups derived from HCF's and HCFC's subsequent th the initial H atom abstraction by HO radicals. At present, virtually no kinetic data exist for the majority of these reactions, particularly for those involving RO. Potential degradation intermediates and final products include a large variety of fluorine- and/or chlorine-containing carbonyls, acids, peroxy acids, alcohols, hydrogen peroxides, nitrates and peroxy nitrates, as summarized in the attached table. Probably atmospheric lifetimes of these compounds were also estimated. For some carbonyl and nitrate products shown in this table, there seem to be no significant gas-phase removal mechanisms. Further chemical kinetics and photochemical data are needed to quantitatively assess the atmospheric fate of HCF's and HCFC's, and of the degradation products postulated in this report.

  9. Estimation of Flammability Limits of Selected Fluorocarbons with F(sub 2) and CIF(sub3)

    SciTech Connect

    Trowbridge, L.D.

    1999-09-01

    During gaseous diffusion plant operations, conditions leading to the formation of flammable gas mixtures may occasionally arise. Currently, these could consist of the evaporative coolant CFC-114 and fluorinating agents such as F(sub 2) and CIF(sub 3). Replacement of CFC-114 with non-ozone-depleting substitutes such as c-C(sub 4)F(sub 8) and C(sub 4)F(sub 10) is planned. Consequently, in the future, these too must be considered potential ''fuels'' in flammable gas mixtures. Two questions of practical interest arise: (1) can a particular mixture sustain and propagate a flame if ignited, and (2) what is the maximum pressure that can be generated by the burning (and possibly exploding) gas mixture, should ignite? Experimental data on these systems are limited. To assist in answering these questions, a literature search for relevant data was conducted, and mathematical models were developed to serve as tools for predicting potential detonation pressures and estimating (based on empirical correlations between gas mixture thermodynamics and flammability for known systems) the composition limits of flammability for these systems. The models described and documented in this report are enhanced versions of similar models developed in 1992.

  10. Conclusions and Federal actions

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Findings regarding fluorocarbon production, the roles of ozone and fluorocarbons in atmospheric chemistry, the depletion of stratospheric ozone by fluorocarbons, and various effects of this depletion are outlined. Research into these areas is described and recommendations are given for governmental action to reduce the release of fluorocarbons to the environment.

  11. Semiempirical molecular orbital calculations of anisotropic 1H, 13C and 19F hyperfine coupling constants in hydrocarbon and fluorocarbon radicals

    NASA Astrophysics Data System (ADS)

    Barfield, Michael; Babaqi, Abdulla S.; Doddrell, David M.; Gottlieb, Hans P. W.

    The anisotropic hyperfine coupling constants (AHCC) from the electron spin resonance (E.S.R.) spectra of a variety of atoms in organic radicals have been calculated by means of semiempirical molecular orbital wavefunctions in the INDO approximation. Hyperfine tensors involving 1H, 13C and 19F nuclei are obtained for the ĊH, ĊH3, CH3ĊH2, (CH3)3Ċ hydrocarbon radicals, malonic acid radical, ĊH2F, ĊF2H, ĊF3 and CF3ĊH2 radicals. The calculated values are compared with available experimental, non-empirical and semiempirical values for these radicals. All integrals of the operator entering the electronic contributions have been evaluated over Slater type orbitals. The introduction of deorthogonalized wavefunctions gives generally better calculated results. In particular, the tensor components of the 19F AHCC are in good agreement with the experimental results without the necessity of readjusting the effective nuclear charges.

  12. Effect of fluorocarbon self-assembled monolayer films on sidewall adhesion and friction of surface micromachines with impacting and sliding contact interfaces

    SciTech Connect

    Xiang, H.; Komvopoulos, K.

    2013-06-14

    A self-assembled monolayer film consisting of fluoro-octyltrichlorosilane (FOTS) was vapor-phase deposited on Si(100) substrates and polycrystalline silicon (polysilicon) surface micromachines. The hydrophobic behavior and structural composition of the FOTS film deposited on Si(100) were investigated by goniometry and X-ray photoelectron spectroscopy, respectively. The effects of contact pressure, relative humidity, temperature, and impact/sliding cycles on the adhesive and friction behavior of uncoated and FOTS-coated polysilicon micromachines (referred to as the Si and FOTS/Si micromachines, respectively) were investigated under controlled loading and environmental conditions. FOTS/Si micromachines demonstrated much lower and stable adhesion than Si micromachines due to the highly hydrophobic and conformal FOTS film. Contrary to Si micromachines, sidewall adhesion of FOTS/Si micromachines demonstrated a weak dependence on relative humidity, temperature, and impact cycles. In addition, FOTS/Si micromachines showed low and stable adhesion and low static friction for significantly more sliding cycles than Si micromachines. The adhesive and static friction characteristics of Si and FOTS/Si micromachines are interpreted in the context of physicochemical surface changes, resulting in the increase of the real area of contact and a hydrophobic-to-hydrophilic transition of the surface chemical characteristics caused by nanoscale surface smoothening and the removal of the organic residue (Si micromachines) or the FOTS film (FOTS/Si micromachines) during repetitive impact and oscillatory sliding of the sidewall surfaces.

  13. The Influence of Fluorocarbon and Hydrocarbon Acyl Groups at the Surface of Bovine Carbonic Anhydrase II on the Kinetics of Denaturation by Sodium Dodecyl Sulfate

    PubMed Central

    Lee, Andrew; Mirica, Katherine A.; Whitesides, George M.

    2011-01-01

    This paper examines the influence of acylation of the Lys-ε-NH3+ groups of bovine carbonic anhydrase (BCA, E.C. 4.2.1.1) to Lys-ε-NHCOR (R = -CH3, -CH2CH3, and -CH(CH3)2, -CF3) on the rate of denaturation of this protein in buffer containing sodium dodecyl sulfate (SDS). Analysis of the rates suggested separate effects due to electrostatic charge and hydrophobic interactions. Rates of denaturation (kAc,n) of each series of acylated derivatives depended on the number of acylations (n). Plots of log kAc,n vs. n followed U-shaped curves. Within each series of derivatives, rates of denaturation decreased as n increased to ~7; this decrease was compatible with increasingly unfavorable electrostatic interactions between SDS and protein. In this range of n, rates of denaturation also depended on the choice of the acyl group as n increased to ~7, in a manner compatible with favorable hydrophobic interactions between SDS and the -NHCOR groups. As n increased in the range 7 < n < 14 however, rates of denaturation stayed approximately constant; analysis suggested these rates were compatible with an increasingly important contribution to denaturation that depended both on the net negative charge of the protein and on the hydrophobicity of the R group. The mechanism of denaturation thus seems to change with the extent of acylation of the protein. For derivatives with the same net electrostatic charge, rates of denaturation increased with the acyl group (by a factor of ~3 for n ~ 14) in the order CH3CONH- < CH3CH2CONH- < (CH3)2CHCONH- < CF3CONH-. These results suggested that the hydrophobicity of CF3CONH- is slightly greater (by a factor of < 2) than that of RHCONH- similar in surface area. PMID:21182314

  14. Fluorocarbon Contamination from the Drill on the Mars Science Laboratory: Potential Science Impact on Detecting Martian Organics by Sample Analysis at Mars (SAM)

    NASA Technical Reports Server (NTRS)

    Eigenbrode, J. L.; McAdam, A.; Franz, H.; Freissinet, C.; Bower, H.; Floyd, M.; Conrad, P.; Mahaffy, P.; Feldman, J.; Hurowitz, J.; Evans, J.; Anderson, M.; Jandura, L.; Brown, K.; Logan, C.; Kuhn, S.; Anderson, R.; Beegle, L.; Limonadi, D.; Rainen, R.; Umland, J.

    2013-01-01

    Polytetrafluoroethylene (PTFE or trade name: Teflon by Dupont Co.) has been detected in rocks drilled during terrestrial testing of the Mars Science Laboratory (MSL) drilling hardware. The PTFE in sediments is a wear product of the seals used in the Drill Bit Assemblies (DBAs). It is expected that the drill assembly on the MSL flight model will also shed Teflon particles into drilled samples. One of the primary goals of the Sample Analysis at Mars (SAM) instrument suite on MSL is to test for the presence of martian organics in samples. Complications introduced by the potential presence of PTFE in drilled samples to the SAM evolved gas analysis (EGA or pyrolysisquadrupole mass spectrometry, pyr-QMS) and pyrolysis- gas chromatography mass spectrometry (Pyr- GCMS) experiments was investigated.

  15. Effect of Low-frequency Power on F, CF2 Relative Density and F/CF2 Ratio in Fluorocarbon Dual-Frequency Plasmas

    NASA Astrophysics Data System (ADS)

    Huang, Hongwei; Ye, Chao; Xu, Yijun; Yuan, Yuan; Shi, Guofeng; Ning, Zhaoyuan

    2010-10-01

    Effect of low-frequency power on F, CF2 relative density and F/CF2 ratio, in C2F6, C4F8 and CHF3 dual-frequency capacitively couple discharge driven by the power of 13.56 MHz/2 MHz, was investigated by using optical emission spectroscopy. High F, CF2 relative density and high F/CF2 ratio were obtained in a CHF3 plasma. But for C2F6 and C4F8 plasmas, the F, CF2 relative density and F/CF2 ratio all decreased significantly due to the difference in both reactive paths and reactive energy. The increase of LF power caused simultaneous increase of F and CF2 radical relative densities in C4F8 and CHF3 plasmas, but led to increase of F with the decrease in CF2 relative densities in C2F6 plasma due to the increase of lower energy electrons and the decrease of higher energy electrons in electron energy distribution function (EEDF).

  16. Surface kinetics modeling of silicon and silicon oxide plasma etching. III. Modeling of silicon oxide etching in fluorocarbon chemistry using translating mixed-layer representation

    SciTech Connect

    Kwon, Ohseung; Bai Bo; Sawin, Herbert H.

    2006-09-15

    Silicon oxide etching was modeled using a translating mixed-layer model, a novel surface kinetic modeling technique, and the model showed good agreement with measured data. Carbon and fluorine were identified as the primary contributors to deposition and etching, respectively. Atomic fluorine flux is a major factor that determines the etching behavior. With a chemistry having a small amount of atomic fluorine (such as the C{sub 4}F{sub 8} chemistry), etching yield shows stronger dependence on the composition change in the gas flux.

  17. Growth of fluorocarbon macromolecules in the gas phase: IV. Li+-attachment mass spectrometric investigation of high-mass neutral radicals in the downstream region of Ar/c-C4F8 plasmas

    NASA Astrophysics Data System (ADS)

    Okumura, Hiroshi; Furuya, Kenji; Harata, Akira

    2009-03-01

    Mass analysis has been conducted on neutral species in the downstream region of Ar/c-C4F8 plasmas by Li+-attachment mass spectrometry. Various peaks appeared in the mass spectrum observed in the case of 29% c-C4F8, and many of them have unambiguously been assigned to the Li+ adducts of neutral radicals with odd-numbered fluorine atoms from 2n + 1 to 2n - 5, where n means the number of carbon atoms, as well as neutral species with even-numbered fluorine atoms from 2n + 2 to 2n - 10. In contrast, only the peaks due to CnF2n+2 (n = 1-7), CnF2n (n = 1, 4-8), CnF2n-2 (n = 3, 5-8) and C9F14 appeared in the case of 2.2% c-C4F8. These findings demonstrate that the Li+-attachment ionization is fragment-free, not only for relatively stable perfluorocarbon species but also for their neutral radicals, and therefore effective for the identification of high-mass neutral perfluorocarbon radicals. The analysis of the growth mechanisms of CnF2n+2 and CnF2n on the basis of thermochemistry has proposed CF3CF as an important reactant.

  18. Recovery of purified helium or hydrogen from gas mixtures

    DOEpatents

    Merriman, J.R.; Pashley, J.H.; Stephenson, M.J.; Dunthorn, D.I.

    1974-01-15

    A process is described for the removal of helium or hydrogen from gaseous mixtures also containing contaminants. The gaseous mixture is contacted with a liquid fluorocarbon in an absorption zone maintained at superatomspheric pressure to preferentially absorb the contaminants in the fluorocarbon. Unabsorbed gas enriched in hydrogen or helium is withdrawn from the absorption zone as product. Liquid fluorocarbon enriched in contaminants is withdrawn separately from the absorption zone. (10 claims)

  19. Process for the separation of components from gas mixtures

    DOEpatents

    Merriman, J.R.; Pashley, J.H.; Stephenson, M.J.; Dunthorn, D.I.

    1973-10-01

    A process for the removal, from gaseous mixtures of a desired component selected from oxygen, iodine, methyl iodide, and lower oxides of carbon, nitrogen, and sulfur is described. The gaseous mixture is contacted with a liquid fluorocarbon in an absorption zone maintained at superatmospheric pressure to preferentially absorb the desired component in the fluorocarbon. Unabsorbed constituents of the gaseous mixture are withdrawn from the absorption zone. Liquid fluorocarbon enriched in the desired component is withdrawn separately from the zone, following which the desired component is recovered from the fluorocarbon absorbent. (Official Gazette)

  20. High performance rolling element bearing

    NASA Technical Reports Server (NTRS)

    Bursey, Jr., Roger W. (Inventor); Olinger, Jr., John B. (Inventor); Owen, Samuel S. (Inventor); Poole, William E. (Inventor); Haluck, David A. (Inventor)

    1993-01-01

    A high performance rolling element bearing (5) which is particularly suitable for use in a cryogenically cooled environment, comprises a composite cage (45) formed from glass fibers disposed in a solid lubricant matrix of a fluorocarbon polymer. The cage includes inserts (50) formed from a mixture of a soft metal and a solid lubricant such as a fluorocarbon polymer.

  1. Utilization of oxygen difluoride for syntheses of fluoropolymers

    NASA Technical Reports Server (NTRS)

    Toy, M. S. (Inventor)

    1976-01-01

    The reaction oxygen difluoride, OF2, with ethylenically unsaturated fluorocarbon compounds is examined. Depending upon the fluorocarbon material and reaction conditions, OF2 can chain extend fluoropolyenes, convert functional perfluorovinyl groups to acyl fluoride and/or epoxide groups, and act as a monomer for an addition type copolymerization with diolefins.

  2. 10 CFR Appendix E to Part 110 - Illustrative List of Chemical Exchange or Ion Exchange Enrichment Plant Equipment and Components...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    .... Plastic, plastic-lined (including use of fluorocarbon polymers) and/or glass-lined columns and piping are...) or glass. The stage residence time of the columns is designed to be short (30 seconds or less). (2... fluorocarbon polymers) or are lined with glass. The stage residence time of the centrifugal contactors...

  3. Method of bonding diamonds in a matrix and articles thus produced

    DOEpatents

    Taylor, G.W.

    1981-01-27

    By fluorinating diamond grit, the grit may be readily bonded into a fluorocarbon resin matrix. The matrix is formed by simple hot pressing techniques. Diamond grinding wheels may advantageously be manufactured using such a matrix. Teflon fluorocarbon resins are particularly well suited for using in forming the matrix.

  4. Development of a special purpose spacecraft coating, phase 4

    NASA Technical Reports Server (NTRS)

    Gillman, H. D.

    1980-01-01

    Coating formulations based on a fluorocarbon resin were evaluated for use on spacecraft exteriors. Formulations modified with an acrylic resin were found to have excellent offgassing properties. A much less expensive process for increasing to solid content of the fluorocarbon latex was developed.

  5. Texturing polymer surfaces by transfer casting. [cardiovascular prosthesis

    NASA Technical Reports Server (NTRS)

    Banks, B. A.; Weigand, A. J.; Sovey, J. S. (Inventor)

    1982-01-01

    A technique for fabricating textured surfaces on polymers without altering their surface chemistries is described. A surface of a fluorocarbon polymer is exposed to a beam of ions to texture it. The polymer which is to be surface-roughened is then cast over the textured surface of the fluorocarbon polymer. After curing, the cast polymer is peeled off the textured fluorocarbon polymer, and the peeled off surface has negative replica of the textured surface. The microscopic surface texture provides large surface areas for adhesive bonding. In cardiovascular prosthesis applications the surfaces are relied on for the development of a thin adherent well nourished thrombus.

  6. Long-lasting solid-polymer electrolytic hygrometer

    NASA Technical Reports Server (NTRS)

    Lawson, D. D.

    1978-01-01

    Device consists of hollow tube node of oxidation-resistant sulfonated fluorocarbon polymer. Tube absorbs moisture from air passing across inner and outer surfaces, causing change in polymer conductance. Change is related to change in water content in gas sample.

  7. 16 CFR 423.1 - Definitions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... uses any common organic solvent (e.g. petroleum, perchlorethylene, fluorocarbon). The process may also... and agitation. When no temperature is given, e.g., warm or cold, hot water up to 145 degrees F...

  8. Comprehensive Bio-Imaging with Fluorinated Nanoparticles Using Breathable Liquids

    PubMed Central

    Kurczy, Michael E.; Zhu, Zheng Jiang; Ivanisevic, Julijana; Schuyler, Adam M.; Lalwani, Kush; Santidrian, Antonio F.; David, John W.; Giddabasappa, Anand; Roberts, Amanda; Olivos, Hernando J.; O'Brien, Peter J.; Franco, Lauren; Fields, Matthew W.; Paris, Liliana P.; Friedlander, Martin; Johnson, Caroline H.; Epstein, Adrian; Gendleman, Howard E.; Wood, Malcolm; Felding-Habermann, Brunhilde; Patti, Gary J.; Spilker, Mary E.; Siuzdak, Gary

    2015-01-01

    Fluorocarbons are lipophobic and non-polar molecules that exhibit remarkable bio-compatibility, with applications in liquid ventilation and synthetic blood. The unique properties of these compounds have also enabled mass spectrometry imaging of tissues where the fluorocarbons act as a Teflon-like coating for nanostructured surfaces to assist in desorption/ionization. Here we report fluorinated gold nanoparticles (f-AuNPs) designed to facilitate nanostructure imaging mass spectrometry. Irradiation of f-AuNPs results in the release of the fluorocarbon ligands providing a driving force for analyte desorption. The f-AuNPs allow for the mass spectrometry analysis of both lipophilic and polar (central carbon) metabolites. An important property of AuNPs is that they also act as contrast agents for X-ray microtomography and electron microscopy, a feature we have exploited by infusing f-AuNPs into tissue via fluorocarbon liquids to facilitate multi-modal (molecular and anatomical) imaging. PMID:25601659

  9. Amorphous microcellular polytetrafluoroethylene foam film

    NASA Astrophysics Data System (ADS)

    Tang, Chongzheng

    1991-11-01

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

  10. Atmospheric trace gas measurements with a new clean air sampling system

    SciTech Connect

    Leifer, R.; Sommers, K.; Guggenheim, S.F.

    1981-10-01

    The development of a new clean air sampling system for the Department of Energy's WB-57F aircraft has allowed the analysis of CCl/sub 3/F (Fluorocarbon-11), CCl/sub 2/F/sub 2/ (Fluorocarbon-12), CHClF/sub 2/ (Fluorocarbon-22), C/sub 2/Cl/sub 3/F/sub 3/ (Fluorocarbon-113), CH/sub 4/, CO, CO/sub 2/, N/sub 2/O, CH/sub 3/Cl, CCl/sub 4/, CH/sub 3/CCl/sub 3/, OCS and SF/sub 6/ in tropospheric and stratospheric samples. Samples collected during the interception of the plume from the eruption of Mount St. Helens indicate that OCS was injected into the stratosphere during the eruption. A large CO/sub 2/ gradient was found at 19.2 km on this flight.

  11. 40 CFR 414.40 - Applicability; description of the thermoplastic resins subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Anhydride Resins Styrene Polymeric Residue *Styrene-Acrylic Copolymer Resins *Styrene-Acrylonitrile... *Ethylene-Methacrylic Acid Copolymers *Ethylene-Vinyl Acetate Copolymers *Fatty Acid Resins *Fluorocarbon... Polyacrylic Acid *Polyamides *Polyarylamides Polybutadiene *Polybutenes Polybutenyl Succinic...

  12. SUMMARY REVIEW OF HEALTH EFFECTS ASSOCIATED WITH HYDROGEN FLUORIDE AND RELATED COMPOUNDS: HEALTH ISSUE ASSESSMENT

    EPA Science Inventory

    The major natural sources of airborne hydrogen fluoride (HF) are volcanic activity, ocean spray, and crustal weathering of fluoride-containing rocks. Anthropogenic sources include emissions from industrial operations such as aluminum and fluorocarbon production, and uranium proce...

  13. Comprehensive bioimaging with fluorinated nanoparticles using breathable liquids

    NASA Astrophysics Data System (ADS)

    Kurczy, Michael E.; Zhu, Zheng-Jiang; Ivanisevic, Julijana; Schuyler, Adam M.; Lalwani, Kush; Santidrian, Antonio F.; David, John M.; Giddabasappa, Anand; Roberts, Amanda J.; Olivos, Hernando J.; O'Brien, Peter J.; Franco, Lauren; Fields, Matthew W.; Paris, Liliana P.; Friedlander, Martin; Johnson, Caroline H.; Epstein, Adrian A.; Gendelman, Howard E.; Wood, Malcolm R.; Felding, Brunhilde H.; Patti, Gary J.; Spilker, Mary E.; Siuzdak, Gary

    2015-01-01

    Fluorocarbons are lipophobic and non-polar molecules that exhibit remarkable biocompatibility, with applications in liquid ventilation and synthetic blood. The unique properties of these compounds have also enabled mass spectrometry imaging of tissues where the fluorocarbons act as a Teflon-like coating for nanostructured surfaces to assist in desorption/ionization. Here we report fluorinated gold nanoparticles (f-AuNPs) designed to facilitate nanostructure imaging mass spectrometry. Irradiation of f-AuNPs results in the release of the fluorocarbon ligands providing a driving force for analyte desorption. The f-AuNPs allow for the mass spectrometry analysis of both lipophilic and polar (central carbon) metabolites. An important property of AuNPs is that they also act as contrast agents for X-ray microtomography and electron microscopy, a feature we have exploited by infusing f-AuNPs into tissue via fluorocarbon liquids to facilitate multimodal (molecular and anatomical) imaging.

  14. Search for plutonium-244 tracks in mountain pass bastnaesite

    USGS Publications Warehouse

    Fleischer, R.L.; Naeser, C.W.

    1972-01-01

    WE have found that bastnaesite, a rare earth fluorocarbonate, from the Precambrian Mountain Pass deposit has an apparent Cretaceous fission track age, and hence does not reveal any anomalous fission tracks due to 244Pu. ?? 1972 Nature Publishing Group.

  15. Thermally resistant polymers for fuel tank sealants

    NASA Technical Reports Server (NTRS)

    Webster, J. A.

    1972-01-01

    Conversion of fluorocarbon dicarboxylic acid to intermediates whose terminal functional groups permit polymerization is discussed. Resulting polymers are used as fuel tank sealers for jet fuels at elevated temperatures. Stability and fuel resistance of the prototype polymers is explained.

  16. "Proplast" for keratoprosthesis.

    PubMed

    White, J H; Gona, O

    1988-05-01

    'Proplast,' a Teflon fluorocarbon polymer and carbon fiber composite, was used as support for a polymethyl-methacrylate cylinder in a keratoprosthesis that was implanted in rabbit corneas with successful retention for up to 3 years. PMID:3399261

  17. Earth's Endangered Ozone

    ERIC Educational Resources Information Center

    Panofsky, Hans A.

    1978-01-01

    Included are (1) a discussion of ozone chemistry; (2) the effects of nitrogen fertilizers, fluorocarbons, and high level aircraft on the ozone layer; and (3) the possible results of a decreasing ozone layer. (MR)

  18. HYDRAULIC STUDIES AND CLEANING EVALUATIONS OF ULTRAVIOLET DISINFECTION UNITS

    EPA Science Inventory

    Various types of operating ultraviolet disinfection reactor designs were evaluated for hydraulic characteristics and cleaning requirements. The fluorocarbon polymer tube designs promote plug-flow behavior because of their relatively high length-to-diameter ratio. Hydraulic evalua...

  19. Cell growth on liquid interfaces: Role of surface active compounds

    PubMed Central

    Keese, Charles R.; Giaever, Ivar

    1983-01-01

    Anchorage-dependent fibroblasts can be cultured by using as a substrate the protein layer that spontaneously forms at the liquid-liquid interface between fluorocarbon fluids and tissue culture medium. For this novel substrate to be effective in supporting confluent cell layers, the protein monolayer must support the stresses exerted by spreading fibroblasts. The composition of the fluorocarbon fluid has a significant effect on the strength of the protein layer and, thus, on the patterns of cell growth. Evidence is presented demonstrating that a protein film, sufficiently strong to support cell growth, does not occur on purified fluorocarbon fluids but requires the presence of trace amounts of polar, surface active compounds. By the addition of small quantities of pentafluorobenzoyl chloride to alumina-treated fluorocarbon fluids, excellent interfacial substrates can be produced. We have applied this understanding to produce a liquid microcarrier system capable of general use with a variety of cells, including human fibroblasts. A microcarrier in which the fluorocarbon is replaced with polydimethyldiphenyl siloxane is also described. Images PMID:16593369

  20. Development of an all-metal thick film cost effective metallization system for solar cells

    NASA Technical Reports Server (NTRS)

    Ross, B.; Parker, J.

    1982-01-01

    Electrodes made with pastes produced under the previous contract were analyzed and compared with raw materials. A needle-like structure observed on the electroded solar cell was identified as eutectic copper-silicon, a phase considered to benefit the electrical and metallurgical properties of the contact. Electrodes made from copper fluorocarbon and copper silver fluoride also contained this phase but had poor adhesion. A liquid medium, intended to provide transport during carbon fluoride decomposition was incorporated into the paste resulting in better adhesion. The product survived preliminary environmental tests. A 2 cm by 2 cm solar cell made with fluorocarbon activated copper electrodes and gave 7% AMI efficiency (without AR coating). Both silver fluoride and fluorocarbon screened paste electrodes can be produced for approximately $0.04 per watt.

  1. Plasma fluorination of carbon-based materials for imprint and molding lithographic applications

    PubMed Central

    Schvartzman, M.; Mathur, A.; Hone, J.; Jahnes, C.; Wind, S. J.

    2008-01-01

    Diamondlike carbon nanoimprint templates are modified by exposure to a fluorocarbon-based plasma, yielding an ultrathin layer of a fluorocarbon material on the surface which has a very low surface energy with excellent antiwear properties. We demonstrate the use of these plasma fluorinated templates to pattern features with dimensions ∼20 nm and below. Furthermore, we show that this process is extendable to other carbon-based materials. Plasma fluorination can be applied directly to nanoimprint resists as well as to molds used to form elastomer stamps for microcontact printing and other applications requiring easy mold release. PMID:19529791

  2. Behavior of cells at fluid interfaces.

    PubMed Central

    Giaever, I; Keese, C R

    1983-01-01

    We have cultured the murine cell lines 3T3-L1 and SV-T2 using as a substrate the layer of denatured protein that forms at the phase boundary between culture medium and fluorocarbon fluids. The growth patterns observed on these interfaces differ from those seen on conventional solid substrates. Depending on the cell strain and the composition of the fluorocarbon fluid, cells will tend to clump into isolated aggregates or form nearly confluent cell monolayers containing "lake-like" openings. We demonstrate that these growth patterns can be attributed to the ability of cultured cells to stress and break the protein monolayer on which they grow. Images PMID:6571995

  3. Vacuum ultraviolet radiation/atomic oxygen synergism in materials reactivity

    NASA Technical Reports Server (NTRS)

    Koontz, Steven; Leger, Lubert; Albyn, Keith; Cross, Jon

    1990-01-01

    Experimental results are presented which indicate that low fluxes of vacuum UV (VUV) radiation exert a pronounced influence on the atomic oxygen reactivity of such fluorocarbon and fluorocarbon spacecraft materials as the FEP Teflon and PCTFE that are under consideration for the Space Station Freedom. With simultaneous exposure to VUV fluxes comparable to those experienced in LEO, the reactivity of these materials becomes comparable to that of Kapton; VUV radiation has also been shown to increase the reactivity of Kapton with thermal-energy oxygen atoms.

  4. Acoustic lens is gas-filled

    NASA Technical Reports Server (NTRS)

    Kendall, J. M., Jr.

    1981-01-01

    Fluorocarbon gas contained by plastic membrane is effective lens for sound waves. In tests, lens substantially improved accuracy of sound "maps" of turbulent airflow. It could also be used to record sound intensity patterns in design of speakers, lecture halls, and auditoriums. Lens is fabricated by clamping together two membranes of thin plastic and filling enclosed space with fluorocarbon gas. Since speed of sound in gas is considerably less than in air, lens refracts and focuses sound waves, analogous to focusing light by glass lens. Focal length is adjusted simply by changing gas pressure, which changes lens curvature.

  5. Development of a special purpose spacecraft interior coating. Phase 2. [fire resistant fluoropolymer coating

    NASA Technical Reports Server (NTRS)

    Bartoszek, E. J.; Christofas, A.; Nannelli, P.

    1977-01-01

    Numerous acrylic and epoxy modifiers for the fluorocarbon latex resin base were investigated. Optimum coatings were developed by modifying the fluorocarbon latex with an epoxy acrylic resin system. In addition, a number of other formulations, containing hard acrylics as modifiers, displayed attractive properties and potential for further improvements. The preferred formulations dried to touch in about one hour and were fully dried in about twenty four hours under normal room temperature and humidity conditions. In addition to physical and mechanical properties either comparable or superior to those of commercial solvent base polyurethane or polyester coatings, the preferred compositions meet the flammability and offgassing requirements specified by NASA.

  6. Hydrophobic-induced Surface Reorganization: Molecular Dynamics Simulations of Water Nanodroplet on Perfluorocarbon Self-Assembled Monolayers

    PubMed Central

    Park, Sung Hyun; Carignano, Marcelo A.; Nap, Rikkert J.; Szleifer, Igal

    2010-01-01

    We carried out molecular dynamics simulations of water droplets on self-assembled monolayers of perfluorocarbon molecules. The interactions between the water droplet and the hydrophobic fluorocarbon surface were studied by systematically changing the molecular surface coverage and the mobility of the tethered head groups of the surface chain molecules. The microscopic contact angles were determined for different fluorocarbon surface densities. The contact angle at a nanometer length scale does not show a large change with the surface density. The structure of the droplets was studied by looking at the water density profiles and water penetration near the hydrophobic surface. At surface densities near close packed coverage of fluorocarbons, the water density shows an oscillating pattern near the boundary with a robust layered structure. As the surface density decreased and more water molecules penetrated into the fluorocarbon surface, the ordering of the water molecules at the boundary became less pronounced and the layered density structure became diffuse. The water droplet is found to induce the interfacial surface molecules to rearrange and form unique topological structures that minimize the unfavorable water-surface contacts. The local density of the fluorocarbon molecules right below the water droplet is measured to be higher than the density outside the droplet. The density difference increases as the overall surface density decreases. Two different surface morphologies emerge from the water-induced surface reorganization over the range of surface coverage explored in the study. For surface densities near closed packed monolayer coverage, the height of the fluorocarbons is maximum at the center of the droplet and minimum at the water-vapor-surface triple junction, generating a convex surface morphology under the droplet. For lower surface densities, on the other hand, the height of the fluorocarbon surface becomes maximal at and right outside the water-vapor-surface contact line and decreases quickly towards the center of the droplet, forming a concave shape of the surface. The interplay between the fluorocarbon packing and the water molecules is found to have profound consequences in many aspects of surface-water interactions, including water depletion and penetration, hydrogen bonding, and surface morphologies. PMID:20514368

  7. Novel CO{sub 2}-thickeners for improved mobility control

    SciTech Connect

    Enick, Dr. Robert M.; Beckman, Dr. Eric J.; Hamilton, Dr. Andrew

    2000-02-02

    The objective of this study was to design, synthesize, and characterize thickening agents for dense carbon dioxide and to evaluate their solubility and viscosity-enhancing potential in CO{sub 2}. Hydrocarbon-fluorocarbon random copolymers, sulfated hydrocarbon-fluorocarbon random copolymers, semifluorinated trialkyltin fluorides and small hydrogen-bonding compounds were evaluated. Random copolymers of styrene and heptadecafluorodecyl acrylate were characterized by high solubility ion dense carbon dioxide and the most substantial increases in solution viscosity. Falling cylinder viscometry results indicated that the 29%styrene--71%fluoroacylate bulk-polymerized copolymer induced 2--250 fold increases in viscosity at copolymer concentrations of 0.2--5.0wt%.

  8. Novel CO{sub 2}-thickeners for improved mobility control

    SciTech Connect

    Enick, Dr. Robert M.; Beckman, Dr. Eric J.; Hamilton, Dr. Andrew

    2000-02-02

    The objective of this study was to design, synthesize, and characterize thickening agents for dense carbon dioxide and to evaluate their solubility and viscosity-enhancing potential in CO{sub 2}. Previously, fluoroacrylate homopolymers and fluorinated telechelic ionomers were shown to increase the viscosity of carbon dioxide by a factor of 3--4 at concentrations of 2--3 at concentrations of 4--5 wt%. This report details the findings for several new types of carbon dioxide thickening candidates. Hydrocarbon-fluorocarbon random copolymers, sulfonated hydrocarbon-fluorocarbon random copolymers, semifluorinated trialkyltin fluorides and small hydrogen-bounding compounds were evaluated.

  9. 46 CFR 130.230 - Protection from refrigerants.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Protection from refrigerants. 130.230 Section 130.230... refrigerants. (a) For each refrigeration system that exceeds 0.6 cubic meters (20 cubic feet) of storage... storage capacity if using a fluorocarbon, as a refrigerant, there must be available one...

  10. 46 CFR 130.230 - Protection from refrigerants.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Protection from refrigerants. 130.230 Section 130.230... refrigerants. (a) For each refrigeration system that exceeds 0.6 cubic meters (20 cubic feet) of storage... storage capacity if using a fluorocarbon, as a refrigerant, there must be available one...

  11. 46 CFR 130.230 - Protection from refrigerants.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Protection from refrigerants. 130.230 Section 130.230... refrigerants. (a) For each refrigeration system that exceeds 0.6 cubic meters (20 cubic feet) of storage... storage capacity if using a fluorocarbon, as a refrigerant, there must be available one...

  12. 46 CFR 130.230 - Protection from refrigerants.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Protection from refrigerants. 130.230 Section 130.230... refrigerants. (a) For each refrigeration system that exceeds 0.6 cubic meters (20 cubic feet) of storage... storage capacity if using a fluorocarbon, as a refrigerant, there must be available one...

  13. The Great Spray Can Debate.

    ERIC Educational Resources Information Center

    Bassow, Herb

    This booklet, designed to be used in high school classrooms, concerns the technological, economic, and political contexts of the fluorocarbon-ozone depletion controversy. The curriculum is divided into three phases: the scientific dimension, which is a pure science analysis using lab-classroom tools and methodologies; the philosophical dimension,…

  14. Organofluorine chemistry: A Janus cyclohexane ring

    NASA Astrophysics Data System (ADS)

    Santschi, Nico; Gilmour, Ryan

    2015-06-01

    The first synthesis of the all-cis isomer of 1,2,3,4,5,6-hexafluorocyclohexane, a molecule with one hydrocarbon face and one fluorocarbon face, is a tour de force of organofluorine chemistry and opens up new possibilities for molecular design.

  15. High-power, ultralow-mass solar arrays: FY-77 solar arrays technology readiness assessment report, volume 2

    NASA Technical Reports Server (NTRS)

    Costogue, E. N.; Young, L. E.; Brandhorst, H. W., Jr.

    1978-01-01

    Development efforts are reported in detail for: (1) a lightweight solar array system for solar electric propulsion; (2) a high efficiency thin silicon solar cell; (3) conceptual design of 200 W/kg solar arrays; (4) fluorocarbon encapsulation for silicon solar cell array; and (5) technology assessment of concentrator solar arrays.

  16. Development of an all-metal thick-film cost-effective metallization system for solar cells

    NASA Technical Reports Server (NTRS)

    Ross, B.

    1981-01-01

    Screened electrodes made from fluorocarbon activated copper paste and silver fluoride activated copper paste, tape adhesion and scratch tests were studied. Experiments were conducted with variations in past parameters, firing conditions, including gas ambients, furnace furniture, silicon surface and others. A liquid medium intended to provide transport during the carbon fluoride decomposition, is incorporated in the paste.

  17. Biology and Politics

    ERIC Educational Resources Information Center

    Whiting, Pat

    1977-01-01

    A state representative from Oregon uses his state as example for political action regarding critical sociobiological issues having great bearing on world ecosystems: pollution, energy-resource allocation, and population density. Discusses ozone depletion, use of fluorocarbons, and the Oregon Energy Policy. Suggests methods of involving educators.…

  18. Plasma fluorination of diamond-like carbon surfaces: mechanism and application to nanoimprint lithography.

    PubMed

    Schvartzman, M; Wind, S J

    2009-04-01

    Diamond-like carbon (DLC) films, used as molds for nanoimprint lithography, were treated with a fluorocarbon-based plasma in order to enhance their anti-adhesion properties. While ellipsometry and atomic force microscope measurements showed negligible changes in thickness and surface roughness after plasma processing, contact angle measurement found fluorine plasma-treated DLC surfaces to be highly hydrophobic, with surface energy values reduced from approximately 45 mJ m(-2) for untreated films to approximately 20-30 mJ m(-2) after fluorination. X-ray photoelectron spectroscopy revealed a thin (from approximately 0.5 to approximately 3 nm) fluorocarbon layer on the DLC surface. Proposed mechanisms for the formation of this layer include two competing processes: etching of DLC and deposition of fluorocarbon material, with one or the other mechanism dominant, depending on the plasma conditions. Fluorocarbon plasma-treated DLC molds for nanoimprint lithography were used to pattern sub-20 nm size features with a high degree of repeatability, demonstrating an extended lifetime of the anti-adhesion coating. PMID:19420525

  19. Ternary gas mixtures for high-voltage industrial insulation

    NASA Astrophysics Data System (ADS)

    Pace, M. O.; Chan, C. C.; Christophorou, L. G.

    1981-10-01

    Gas dielectrics for insulating power apparatus, e.g., gas insulated transmission lines (GITL), were evaluated. Particular attention was given to mixtures using large proportions of an electron moderating gas (viz., N2, CHF3, or 1,1,1-C2H3F3) and smaller quantities of two electron attaching gases: SF6 and one fluorocarbon (e.g., c-C4F8). The proportions were sought at which the three gases function best as a team, moderating free electrons from higher to lower energies and there attaching them. Small amounts of the electron attaching additives can drastically raise the dielectric strength of the moderator. Certain combinations of SF6 and fluorocarbons do not produce the undesirable spark by products associated with either SF6 or fluorocarbons alone and also show improved negative polarity impulse breakdown characteristics over pure SF6. Small scale breakdown measurements were made of various ternary mixtures in the GITL geometry. It was found that nitrogen moderates electrons to extremely low energies, where SF6 attaches; the dipolar gases moderate to somewhat higher energies, where some fluorocarbons attach best.

  20. Comparative description of PFAA developmental toxicity: An update

    EPA Science Inventory

    The perfluoroalkyl acids (PFAAs) are a family of fluorocarbons consisting of a perfluorinated carbon tail (typically 4-12 carbons in length) and an acidic functional moiety, usually carboxylate or sulfonate. These compounds have excellent surface tension reducing properties and h...

  1. Combustion of PTFE: The effects of gravity on ultrafine particle generation

    NASA Technical Reports Server (NTRS)

    McKinnon, Thomas; Todd, Paul; Oberdorster, Gunter

    1996-01-01

    The objective of this project is to obtain an understanding of the effect of gravity on the toxicity of ultrafine particle and gas phase materials produced when fluorocarbon polymers are thermally degraded or burned. The motivation for the project is to provide a basic technical foundation on which policies for spacecraft health and safety with regard to fire and polymers can be formulated.

  2. Accurate Lipophilicity (log?P) Measurements Inform on Subtle Stereoelectronic Effects in Fluorine Chemistry.

    PubMed

    O'Hagan, David; Young, Robert J

    2016-03-14

    Polar exploration: Recently, Linclau and co-workers disclosed a straightforward (19) F-NMR method for determining the log?P values of fluorocarbons. The method is particularly useful for most polar compounds and provides a quantitative way to rationalize the more subtle stereoelectronic consequences of fluorine introduction. PMID:26894548

  3. Liquid breathing - Prevention of pulmonary arterial-venous shunting during acceleration.

    NASA Technical Reports Server (NTRS)

    Sass, D. J.; Ritman, E. L.; Caskey, P. E.; Banchero, N.; Wood, E. H.

    1972-01-01

    Dependent pulmonary atelectasis, arterial-venous shunting, and downward displacement of the heart caused by the gravitational-inertial force environment were prevented in dogs breathing oxygenated liquid fluorocarbon in a whole-body water-immersion respirator. Partial closure of the major airways during part of the expiratory phase of liquid respiration was a significant problem initially but was minimized in subsequent studies.

  4. Transparent Thin Films Deposited onto Polyester Film Substrate by Radio Frequency Sputtering with a Poly(tetrafluoroethylene) Target

    NASA Astrophysics Data System (ADS)

    Seino, Shou; Nagai, Yuki; Kobayashi, Masashi; Iwamori, Satoru; Noda, Kazuhiro

    2013-05-01

    Improvement technologies for antireflection property of transparent plastic substrates are required in computer displays. Inorganic coatings have been used to reduce the surface reflection. We have already reported that fluorocarbon thin films sputtered with a poly(tetrafluoroethylene) (PTFE) target are transparent and can be used for an antireflection film, although the pristine PTFE plate used for the sputtering target is white. The fluorocarbon thin films were deposited onto a polyester (PET) film substrate by an rf sputtering, and characterized their optical properties. Elemental ratio, fluorine for carbon, of the thin films increased and degree of cross-linking of the thin films decreased with an increase of the rf power. Arithmetical surface roughness of the fluorocarbon thin films slightly increased with an increase of the rf power. Surface roughness of the fluorocarbon thin film affects the transmittance as well as the chemical structure of the thin film. To enhance the transparency, the diffuse transmittance should be suppressed, and flat surface thin films should be prepared by the sputtering at lower rf power and pressure.

  5. RETENTION OF HALOCARBONS ON A HEXAFLUOROPROPYLENE EPOXIDE-MODIFIED GRAPHITIZED CARBON BLACK - IV. PROPANE- BASED COMPOUNDS

    EPA Science Inventory

    The retention characteristics of 25 propane-based bromofluorocarbon, chlorocarbon, chlorofluorocarbon, and fluorocarbon fluids have been studied as a function of temperature on a stationary phase consisting of a 5% (m/m) coating of a low-molecular-mass polymer of hexafluoropropyl...

  6. Spectroscopic identification of CHCℓF2 (F-22) in the lower stratosphere

    NASA Astrophysics Data System (ADS)

    Goldman, A.; Murcray, F. J.; Blatherwick, R. D.; Bonomo, F. S.; Murcray, F. H.; Murcray, D. G.

    1981-09-01

    Infrared atmospheric spectra were obtained at ˜0.02 cm-1 resolution during a balloon flight made on 3/23/81. These spectra show an absorption feature near 829 cm-1 which we identify as due to CHCℓF2 (Fluorocarbon 22). A preliminary estimate from the sunset spectra shows approximately 100 pptv F-22 near 15 km.

  7. Gas mixtures for spark gap closing switches

    DOEpatents

    Christophorou, L.G.; McCorkle, D.L.; Hunter, S.R.

    1987-02-20

    Gas mixtures for use in spark gap closing switches comprised of fluorocarbons and low molecular weight, inert buffer gases. To this can be added a third gas having a low ionization potential relative to the buffer gas. The gas mixtures presented possess properties that optimized the efficiency spark gap closing switches. 6 figs.

  8. Lighter-than-Air Science

    ERIC Educational Resources Information Center

    MOSAIC, 1977

    1977-01-01

    Reviews practical applications, particularly in scientific research, of hot air balloons. Recent U.S. governmental projects in near-space research are described. Lists (1) major accomplishments of scientific ballooning, including discoveries in cosmic ray particles, gamma and x-rays, and other radiation; (2) measurement of fluorocarbon

  9. GLOBAL DISTRIBUTION OF SELECTED HALOCARBONS, HYDROCARBONS, SF6, AND N2O

    EPA Science Inventory

    Northern and Southern hemispheric distributions of halogenated species, hydrocarbons, SF6, and N2O are presented. The atmospheric growth rates of selected halocarbons and N2O are characterized. The fluorocarbon 11 and 12 global burden and hemispheric distribution is consistent wi...

  10. Fast-drying coating

    NASA Technical Reports Server (NTRS)

    Bartoszek, E. J.

    1978-01-01

    Nontoxic coating has excellent optical properties and can be pigmented in many different colors. It bonds well, can be applied by conventional methods, weathers well, and is self-extinguishing. Coating composition comprises latex blends of fluorocarbons, acrylic resins, stabilizers, modifiers, variety of inorganic pigments, and other additives. Suitable latex primers have also been developed from acrylic latex base.

  11. Gas mixtures for spark gap closing switches

    DOEpatents

    Christophorou, Loucas G.; McCorkle, Dennis L.; Hunter, Scott R.

    1988-01-01

    Gas mixtures for use in spark gap closing switches comprised of fluorocarbons and low molecular weight, inert buffer gases. To this can be added a third gas having a low ionization potential relative to the buffer gas. The gas mixtures presented possess properties that optimized the efficiency spark gap closing switches.

  12. Demonstrating a Lack of Reactivity Using a Teflon-Coated Pan.

    ERIC Educational Resources Information Center

    Richmond, Thomas G.

    1995-01-01

    Illustrates the chemical resistance of polytetrafluoroethene to mineral acids using an ordinary Teflon-coated frying pan. The demonstration can also be used to lead to a discussion of the long lifetimes of fluorocarbons and chlorofluorocarbons in the atmosphere and their roles in the breakdown of the ozone layer. (AIM)

  13. Cardiovascular disease and environmental exposure.

    PubMed Central

    Rosenman, K D

    1979-01-01

    This paper reviews the possible association between cardiovascular disease and occupational and environmental agents. The effects of carbon monoxide, fibrogenic dusts, carbon disulphide, heavy metals, noise, radiation, heat, cold, solvents and fluorocarbons are discussed. New directions for investigation are suggested. PMID:465378

  14. Evaluation of Vacuum Ultraviolet Irradiation Influence under Xenon Excimer Lamp Processing Employing a Quartz Crystal Microbalance with Organic Thin Film

    NASA Astrophysics Data System (ADS)

    Yoshino, Kiyoshi; Matsumoto, Hiroyuki; Iwasaki, Tatsuyuki; Kinoshita, Shinobu; Noda, Kazutoshi; Iwamori, Satoru

    2013-05-01

    The xenon excimer lamp, which emits vacuum ultraviolet radiation, is frequently used as a dry cleaning device for objects such as flat-panel displays (FPDs). UV dry cleaning processes are generally monitored with UV illuminometers, however these do not detect the direct influence of the cleaning process on the substrate. Therefore, a monitoring method that focuses on the treated substrate is required. In this study, we investigated a method to evaluate VUV influence under xenon excimer lamp processing, using a quartz crystal microbalance technique which can detect very small changes in mass. With an organic (fluorocarbon) thin film as the detecting element of the quartz crystal microbalance, we have investigated mass change through irradiation with a xenon excimer lamp, in nitrogen, oxygen, and air atmosphere, respectively. It was confirmed that mass change increased linearly with time, under all conditions, and that monitoring of VUV influence was possible by means of the quartz crystal microbalance method using fluorocarbon thin film.

  15. Scientific Assessment of Stratospheric Ozone: 1989, volume 2. Appendix: AFEAS Report

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The results are presented of the Alternative Fluorocarbon Environmental Acceptability Study (AFEAS), which was organized to evaluate the potential effects on the environment of alternate compounds targeted to replace fully halogenated chlorofluorocarbons (CFCs). All relevant current scientific information to determine the environmental acceptability of the alternative fluorocarbons. Special emphasis was placed on: the potential of the compounds to affect stratospheric ozone; their potential to affect tropospheric ozone; their potential to contribute to model calculated global warming; the atmospheric degradation mechanisms of the compounds, in order to identify their products; and the potential environmental effects of the decomposition products. The alternative compounds to be studied were hydrofluorocarbons (HFCs) with one or two carbon atoms and one or more each of fluorine and hydrogen.

  16. A facile method of fabricating mechanical durable anti-icing coatings based on CeO2 microparticles

    NASA Astrophysics Data System (ADS)

    Wang, Pengren; Peng, Chaoyi; Wu, Binrui; Yuan, Zhiqing; Yang, Fubiao; Zeng, Jingcheng

    2015-07-01

    Compromising between hydrophobicity and mechanical durability may be a feasible approach to fabricating usable anti-icing coatings. This work improves the contact angle of current commercial anti-icing coatings applied to wind turbine blades dramatically and keeps relatively high mechanical durability. CeO2 microparticles and diluent were mixed with fluorocarbon resin to fabricate high hydrophobic coatings on the glass fiber reinforced epoxy composite substrates. The proportion of CeO2 microparticles and diluent influences the contact angles significantly. The optimum mass ratio of fluorocarbon resin to CeO2 microparticles to diluent is 1:1.5:1, which leads to the highest contact angle close to 140°. The microscopy analysis shows that the CeO2 microparticles form nano/microscale hierarchical structure on the surface of the coatings.

  17. Supramolecular Polymers Formed by ABC Miktoarm Star Peptides.

    PubMed

    Lin, Yi-An; Ou, Yu-Chuan; Cheetham, Andrew G; Cui, Honggang

    2013-12-17

    We report here the design and synthesis of an ABC miktoarm star peptide connecting through a lysine junction a short peptide sequence and two hydrophobic but immiscible blocks (a hydrocarbon and a fluorocarbon). The designed molecule can self-assemble into one-dimensional nanostructures with a great diversity of kinetically evolving morphologies in aqueous solution, while molecules that contain only one of the two hydrophobic blocks form structurally similar filaments. We believe the rich assembly behavior and morphological evolution are a direct reflection of the molecular frustration present within the filament core as a result of the in-compatibility of the fluorocarbon and hydrocarbon segments. Our finding opens new opportunities for creating complex supramolecular polymers through the architecture design of small molecular building units. PMID:24490124

  18. Surface modification of PDMS using atmospheric glow discharge polymerization of tetrafluoroethane for immobilization of biomolecules

    NASA Astrophysics Data System (ADS)

    Anand, V.; Ghosh, S.; Ghosh, M.; Rao, G. M.; Railkar, R.; Dighe, R. R.

    2011-08-01

    In this study an atmospheric glow discharge with a fluorocarbon gas as precursor was used to modify the surface of polydimethyl siloxane (PDMS -[(CH 3) 2SiO] n-). The variation in protein immobilizing capability of PDMS was studied for different times of exposure. It was observed that the concentration of proteins adsorbed on the surface varied in an irregular manner with treatment time. The fluorination results in the formation of a thin film of fluorocarbon on the PDMS surface. The AFM and XPS data suggest that the film cracks due to stress and regains its uniformity thereafter. This Stranski-Krastanov growth model of the film was due to the high growth rate offered by atmospheric glow discharge.

  19. Seal Materials Compatible with the Electroplating Solvent Used in Constellation-X Mirrors

    NASA Technical Reports Server (NTRS)

    Pei, Xiong-Skiba

    1999-01-01

    The existing gasket seals used in electroplating of the Constellation-X mirrors are difficult to assemble, and the current seal material is hydrophobic and too thick. The combination of the above problems result in: 1) non-uniform plating; 2) defect sites such as pits on the mirror edges; 3) "bear claws" on the edges of the mandrels and mirrors causing difficulties in shell-mirror separations; and 4) leakage of the plating solution past the seals into the mandrel causing chemical etching of the mandrel interior. This paper reports the results of this summer study in searching for alternate seal materials chemically compatible with the electroplating solvent. Fifteen common elastomeric rubber seal materials made-by Parker Seals were investigated including butyl, ethylene propylene, fluorosilicone, nitrile, Viton fluorocarbon, and silicone. Test results showed that Viton fluorocarbon compounds as a group were superior to the other tested compounds for chemical compatibility with the plating bath.

  20. Supramolecular Polymers Formed by ABC Miktoarm Star Peptides

    PubMed Central

    Lin, Yi-An; Ou, Yu-Chuan; Cheetham, Andrew G.; Cui, Honggang

    2014-01-01

    We report here the design and synthesis of an ABC miktoarm star peptide connecting through a lysine junction a short peptide sequence and two hydrophobic but immiscible blocks (a hydrocarbon and a fluorocarbon). The designed molecule can self-assemble into one-dimensional nanostructures with a great diversity of kinetically evolving morphologies in aqueous solution, while molecules that contain only one of the two hydrophobic blocks form structurally similar filaments. We believe the rich assembly behavior and morphological evolution are a direct reflection of the molecular frustration present within the filament core as a result of the in-compatibility of the fluorocarbon and hydrocarbon segments. Our finding opens new opportunities for creating complex supramolecular polymers through the architecture design of small molecular building units. PMID:24490124

  1. Nanometer-scale water- and proton-diffusion heterogeneities across water channels in polymer electrolyte membranes.

    PubMed

    Song, Jinsuk; Han, Oc Hee; Han, Songi

    2015-03-16

    Nafion, the most widely used polymer for electrolyte membranes (PEMs) in fuel cells, consists of a fluorocarbon backbone and acidic groups that, upon hydration, swell to form percolated channels through which water and ions diffuse. Although the effects of the channel structures and the acidic groups on water/ion transport have been studied before, the surface chemistry or the spatially heterogeneous diffusivity across water channels has never been shown to directly influence water/ion transport. By the use of molecular spin probes that are selectively partitioned into heterogeneous regions of the PEM and Overhauser dynamic nuclear polarization relaxometry, this study reveals that both water and proton diffusivity are significantly faster near the fluorocarbon and the acidic groups lining the water channels than within the water channels. The concept that surface chemistry at the (sub)nanometer scale dictates water and proton diffusivity invokes a new design principle for PEMs. PMID:25630609

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

    NASA Technical Reports Server (NTRS)

    Wheeler, Donald R.; Pepper, Stephen V.

    1990-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Wheeler, Donald R.; Pepper, Stephen V.

    1990-01-01

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

  4. Preparation and Analysis of Type II Xerogel Films with Antifouling/Foul Release Characteristics

    NASA Astrophysics Data System (ADS)

    Sokolova, Anastasiya

    In order to combat biofouling, xerogel coatings comprised of aminopropyl, fluorocarbon, and hydrocarbon silanes were prepared and tested for their antifouling/foul release properties against Ulva, Navicula, barnacles, and tubeworms. Many of the coatings showed settlement and removal of Ulva to be as good as or better than the poly(dimethylsiloxane) (PDMSE) standard. Barnacle removal assays showed excellent results for some coatings while others did not fair so well. The best foul release coatings for barnacles were comprised of aminopropyl/hydrocarbon- and fluorocarbon/hydrocarbon-modified silanes. For the majority of coatings tested, water wettability and surface energy did not play a role in the antifouling/ foul release properties of the coatings.

  5. Novel CO{sub 2}-thickeners for improved mobility control

    SciTech Connect

    Enick, Dr. Robert M.; Beckman, Dr. Eric J.; Hamilton, Dr. Andrew

    2000-02-02

    The objective of this study was to design, synthesize, and characterize thickening agents for dense carbon dioxide and to evaluate their solubility and viscosity-enhancing potential in CO{sub 2}. Previously, hydrocarbon-fluorocarbon random copolymers, sulfated hydrocarbon-fluorocarbon random copolymers, semifluorinated trialkyltin fluorides and small hydrogen-bonding compounds were evaluated. Random copolymers of styrene and heptadecafluorodecyl acrylate yielded substantial increases in viscosity. The amount of styrene varied between 22--40 mole% in the copolymer. Falling cylinder viscometry results indicated that the 29% styrene--71% fluoroacrylate copolymer induced (at 295K and 34.5 Mpa) increases of 10, 60 and 250 at copolymer concentrations of 1, 3 and 5wt%, respectively.

  6. Investigation of test methods, material properties and processes for solar cell encapsulants

    NASA Technical Reports Server (NTRS)

    Willis, P. B.; Baum, B.

    1977-01-01

    The potentially useful encapsulating materials for Task 3 of the Low-Cost Silicon Solar Array project were studied to identify, evaluate, and recommend encapsulant materials and processes for the production of cost-effective, long-life solar cell modules. Materials for study were chosen on the basis of existing knowledge of generic chemical types having high resistance to environmental weathering. The materials varied from rubbers to thermoplastics and presented a broad range of mechanical properties and processing requirements. Basic physical and optical properties were measured on the polymers and were redetermined after exposure to indoor artificial accelerated aging conditions covering four time periods. Strengths and weaknesses of the various materials were revealed and data was accumulated for the development of predictive methodologies. To date, silicone rubbers, fluorocarbons, and acrylic polymers appear to have the most promising combination of characteristics. The fluorocarbons may be used only as films, however, because of their high cost.

  7. Novel Sorption/Desorption Process for Carbon Dioxide Capture (Feasibility Study)

    SciTech Connect

    William Tuminello; Maciej Radosz; Youqing Shen

    2008-11-01

    Western Research Institute and the University of Wyoming Enhanced Oil Recovery Institute have tested a novel approach to carbon dioxide capture in power plants and industrial operations. This approach is expected to provide considerable cost savings, in terms of regeneration of the sorbent. It is proposed that low molecular weight, low volatility liquid fluorocarbons be utilized to absorb CO{sub 2} due to their unusual affinity for the gas. The energy savings would be realized by cooling the fluorocarbon liquids below their melting point where the CO{sub 2} would be released even at elevated pressure. Thus, the expense of heating currently used sorbents, saturated with CO{sub 2}, under low pressure conditions and then having to compress the released gas would not be realized. However, these fluorinated materials have been shown to be poor carbon dioxide absorbers under conditions currently required for carbon capture. The project was terminated.

  8. Novel fluorohydrocarbons

    NASA Technical Reports Server (NTRS)

    Scherer, Kirby V. (Inventor)

    1979-01-01

    Novel fluorohydrocarbons include a fluoroalkyl unit terminating in a tertiary carbon atom which is directly linked to an aliphatic moiety of the compound. The compounds contain at least 9 carbon atoms and usually no more than 13 carbon atoms. The compounds are synthesized by addition of a fluoride atom to the tertiary carbon atom of a fluorocarbon material to form a carbanion followed by alkylation of the carbanion. The fluorohydrocarbons will find use as blood substitutes or as electronic fluids.

  9. Limitations and feasibility of the land disposal of organic solvent-contaminated wastes

    USGS Publications Warehouse

    Roy, W.R.; Griffin, R.A.; Mitchell, J.K.; Mitchell, R.A.

    1989-01-01

    The limitations and feasibility of the land disposal of solid wastes containing inorganic solvents and refrigerants (chlorinated fluorocarbons) were investigated by evaluating the attenuation capacity of a hypothetical waste-disposal site by numerical modeling. The basic theorem of this approach was that the land disposal wastes would be environmentally acceptable if subsurface attenuation reduced groundwater concentrations of organic compounds to concentrations that were less than health-based, water-quality criteria. Computer simulations indicated that the predicted concentrations of 13 of 33 organic compounds in groundwater would be less than their health-based criteria. Hence, solid wastes containing these compounds could be safely disposed at the site. The attenuation capacity of the site was insufficient to reduce concentrations of four compounds to safe levels without limiting the amount of mass available to leach into groundwater. Threshold masses based on time-dependent migration simulations were estimated for these compounds. The remaining 16 compounds, which consisted mainly of chlorinated hydrocarbons and fluorocarbons could not be safely landfilled without severe restrictions on the amounts disposed. These organic compounds were candidates to ban from land disposal.The limitations and feasibility of the land disposal of solid wastes containing organic solvents and refrigerants (chlorinated fluorocarbons) were investigated by evaluating the attenuation capacity of a hypothetical waste-disposal site by numerical mdoeling. Computer simulations indicated that the predicted concentrations of 13 of 33 organic compounds in groundwater would be less than their health-based criteria. Hence, solid wastes containing these compounds could be safely disposed at the site. The attenuation capacity of the site was insufficient to reduce concentrations of four compounds to safe levels without limiting the amount of mass available to leach into groundwater. The remaining 16 compounds, which consisted mainly of chlorinated hydrocarbons and fluorocarbons could not be safely landfilled without severe restrictions on the amounts disposed. These organic compounds were candidates to ban from land disposal.

  10. Antisoiling Coatings for Solar-Energy Devices

    NASA Technical Reports Server (NTRS)

    Cuddihy, E. F.; Willis, P.

    1986-01-01

    Fluorocarbons resist formation of adherent deposits. Promising coating materials reduce soiling of solar photovoltaic modules and possibly solar thermal collectors. Contaminating layers of various degrees of adherence form on surfaces of devices, partially blocking incident solar energy, reducing output power. Loose soil deposits during dry periods but washed off by rain. New coatings help prevent formation of more-adherent, chemically and physically bonded layers rain alone cannot wash away.

  11. The synthesis of poly(ether ether ketone) (PEEK) derived from 1,1-bis(4-hydroxyphenyl)-1-phenyl-2,2,3,3,4,4,4-heptafluorobutane

    SciTech Connect

    Peterman, J.A.; Feld, W.A.

    1995-12-31

    Poly(ether ether ketone)s (PEEK) are of interest due to their high thermal stability. Most PEEK materials are prepared by aromatic nucleophilic substitution between an activated aromatic dihalide and an alkali-metal bisphenolate in polar, aprotic solvents. We now report the preparation of a PEEK containing an extended fluorocarbon chain in the bisphenol, analogous to that produced by McGrath, et. al which contained a trifluoromethyl group in the bisphenol, and examine the effect on thermal properties.

  12. Uptake of trifluoroacetate by Pinus ponderosa via atmospheric pathway

    NASA Astrophysics Data System (ADS)

    Benesch, J. A.; Gustin, M. S.

    Trifluoroacetate (TFA, CF 3COO -), a break down product of hydro(chloro)-fluorocarbons (HFC/HCFCs), has been suggested to contribute to forest decline syndrome. To investigate the possible effects, Pinus ponderosa was exposed to TFA applied as mist (150 and 10,000 ng l -1) to foliar surfaces. Needles accumulated TFA as a function of concentration and time. However, no adverse physiological responses, as plant morphology, photosynthetic and conductance rates, were observed at the TFA concentrations used in this study.

  13. Effect of electron beam irradiation on the properties of crosslinked rubbers

    NASA Astrophysics Data System (ADS)

    Banik, Indranil; Bhowmick, Anil K.

    2000-05-01

    Influence of electron beam (EB) irradiation on the mechanical and dynamic mechanical properties of crosslinked fluorocarbon (FKM) rubber, natural rubber (NR), ethylene propylene diene monomer (EPDM) rubber and nitrile rubber (NBR) has been investigated. The modulus, gel fraction, glass transition temperature ( Tg) and storage modulus increased, while the elongation at the break and the loss tangent (tan δ) Tg decreased. FKM and NBR vulcanizates have been shown to have EB radiation resistance up to 1500 kGy.

  14. New textile composite materials development, production, application

    NASA Technical Reports Server (NTRS)

    Mikhailov, Petr Y.

    1993-01-01

    New textile composite materials development, production, and application are discussed. Topics covered include: super-high-strength, super-high-modulus fibers, filaments, and materials manufactured on their basis; heat-resistant and nonflammable fibers, filaments, and textile fabrics; fibers and textile fabrics based on fluorocarbon poylmers; antifriction textile fabrics based on polyfen filaments; development of new types of textile combines and composite materials; and carbon filament-based fabrics.

  15. REFINING FLUORINATED COMPOUNDS

    DOEpatents

    Linch, A.L.

    1963-01-01

    This invention relates to the method of refining a liquid perfluorinated hydrocarbon oil containing fluorocarbons from 12 to 28 carbon atoms per molecule by distilling between 150 deg C and 300 deg C at 10 mm Hg absolute pressure. The perfluorinated oil is washed with a chlorinated lower aliphatic hydrocarbon, which mairtains a separate liquid phase when mixed with the oil. Impurities detrimental to the stability of the oil are extracted by the chlorinated lower aliphatic hydrocarbon. (AEC)

  16. Fuel cell ion-exchange membrane investigation

    NASA Technical Reports Server (NTRS)

    Toy, M. S.

    1972-01-01

    The present deficiencies in the fluorocarbon sulfonic acid membrane used as the solid polymer electrolyte in the H2/O2 fuel cell are studied. Considered are: Adhesives selection, elastomeric formulations, scavenger exploration, and membrane characterization. The significant data are interpreted and recommendations are given for both short and long range further investigations in two of the four major areas: membrane adhesives and membrane stabilization.

  17. Decompression incidence in air- and liquid-breathing hamsters.

    PubMed

    Lynch, P R; Wilson, J S; Shaffer, T H; Cohen, N

    1983-03-01

    The effects of hyperbaric compression on heart rate, rectal temperature, respiratory rate, bubble formation, and survival were studied in three groups of anesthetized golden hamsters (Mesocricetus auratus). Group I (15 animals) breathed air while exposed to 7 ATA of pressure for 1 h in a hyperbaric chamber; Group II (13 animals), at the same pressure level (7 ATA) and for the same time period (1 h), breathed an oxygenated fluorocarbon liquid (temperature 27 degrees C) that was open to the chamber atmosphere; Group III (10 animals), at the same pressure and time period as the other groups, were sealed in a flexible plastic bag filled with oxygenated fluorocarbon as a breathing mixture. A fourth, Group IV (12 animals), breathed oxygenated fluorocarbon for 1 h at 1 ATA. Survival after rapid decompression in each group varied, 9 animals died in Group I, 12 animals in Group II, whereas none of the animals died in either Groups III or IV. Thirty minutes after decompression postmortem examinations of all the animals demonstrated the presence of large amounts of gas bubbles in the right ventricle and some gas bubbles in the left ventricle of all the hamsters in Groups I and II. No gas bubbles were found in the hearts of the Group III animals. Group III animals, breathing a liquid unsaturated by an inert gas, survived rapid explosive decompression without the signs and symptoms of decompression sickness. Immersion in the liquid fluorocarbon produced a profound decrease in heart rate, rectal temperature, and respiration in Groups II, III, and IV. PMID:6868175

  18. Development of an all-metal thick film cost effective metallization system for solar cells

    NASA Technical Reports Server (NTRS)

    Ross, B.; Parker, J.

    1983-01-01

    Improved thick film solar cell contacts for the high volume production of low cost silicon solar arrays are needed. All metal screenable pastes made from economical base metals and suitable for application to low to high conductivity silicon were examined. Silver fluoride containing copper pastes and fluorocarbon containing copper pastes were discussed. The effect of hydrogen on the adhesion of metals to silicon was investigated. A cost analysis of various paste materials is provided.

  19. The registration of signals from the nuclei other than protons at 0.5 T MRI scanner

    NASA Astrophysics Data System (ADS)

    Anisimov, N.; Volkov, D.; Gulyaev, M.; Pavlova, O.; Pirogov, Yu

    2016-02-01

    The practical aspects of the adaptation of the medical MRI scanner for multinuclear applications are considered. Examples of high resolution NMR spectra for nuclei 19F, 31P, 23Na, 11B, 13C, 2H, and also NQR spectrum for 35Cl are given. Possibilities of MRI for nuclei 19F, 31P, 23Na, 11B are shown. Experiments on registration of signals 19F from the fluorocarbons injected in laboratory animals are described.

  20. Greenhouse effect of chlorofluorocarbons and other trace gases

    NASA Technical Reports Server (NTRS)

    Hansen, James; Lacis, Andrew; Prather, Michael

    1989-01-01

    A comparison is made of the radiative (greenhouse) forcing of the climate system due to changes of atmospheric chlorofluorocarbons and other trace gases. It is found that CFCs, defined to include chlorofluorocarbons, chlorocarbons, and fluorocarbons, now provide about one-quater of current annual increases in anthropogenic greenhouse climate forcing. If the growth rates of CFC production in the early 1970s had continued to the present, current annual growth of climate forcing due to CFCs would exceed that due to CO2.

  1. Development of a special purpose spacecraft interior coating, phase 3

    NASA Technical Reports Server (NTRS)

    Gillman, H. D.; Nannelli, P.

    1979-01-01

    A variety of intumescent coatings based on a fluorocarbon latex resin modified with either an acrylic resin or an epoxy resin were prepared. Several intumescent systems were used for these studies including some based on ammonium polyphosphate and others based on sulfanilamide. The best coatings developed had a high concentration (60-70% by wt.) of intumescent additives and had to be applied thick, approximately 100 mils, in order to have adequate intumescent/fire protection properties.

  2. International research into chlorofluorocarbon (CFC) alternatives

    SciTech Connect

    Marseille, T.J.; Shankle, D.L.; Thurman, A.G.

    1992-05-01

    Selected researchers from 21 countries were queried through questionnaires about their current and planned research activities. The results of the survey show that the majority of research being conducted by the respondents is devoted to investigating the hydrogenated fluorocarbon HFC-134a as a replacement for CFC-12 in refrigeration applications. The main issue with this alternative is identifying compatible lubricants that do not reduce its effectiveness.

  3. Plasma polymerization for cell adhesive/anti-adhesive implant coating

    NASA Astrophysics Data System (ADS)

    Meichsner, Juergen; Testrich, Holger; Rebl, Henrike; Nebe, Barbara

    2015-09-01

    Plasma polymerization of ethylenediamine (C2H8N2, EDA) and perfluoropropane (C3F8, PFP) with admixture of argon and hydrogen, respectively, was studied using an asymmetric 13.56 MHz CCP. The analysis of the plasma chemical gas phase processes for stable molecules revealed consecutive reactions: C2H8N2 consumption, intermediate product NH3, and main final product HCN. In C3F8- H2 plasma the precursor molecule C3F8 and molecular hydrogen are consumed and HF as well as CF4 and C2F6 are found as main gaseous reaction products. The deposited plasma polymer films on the powered electrode are strongly cross-linked due to ion bombardment. The stable plasma polymerized films from EDA are characterized by high content of nitrogen with N/C ratio of about 0.35. The plasma polymerized fluorocarbon film exhibit a reduced F/C ratio of about 1.2. Adhesion tests with human osteoblast cell line MG-63 on coated Ti6Al4V samples (polished) compared with uncoated reference sample yielded both, the enhanced cell adhesion for plasma polymerized EDA and significantly reduced cell adhesion for fluorocarbon coating, respectively. Aging of the plasma polymerized EDA film, in particular due to the reactions with oxygen from air, showed no significant change in the cell adhesion. The fluorocarbon coating with low cell adhesion is of interest for temporary implants. Funded by the Campus PlasmaMed.

  4. Sensitivity of an atmospheric photochemistry model to chlorine perturbations including consideration of uncertainty propagation

    NASA Technical Reports Server (NTRS)

    Stolarski, R. S.; Douglass, A. R.

    1986-01-01

    Models of stratospheric photochemistry are generally tested by comparing their predictions for the composition of the present atmosphere with measurements of species concentrations. These models are then used to make predictions of the atmospheric sensitivity to perturbations. Here the problem of the sensitivity of such a model to chlorine perturbations ranging from the present influx of chlorine-containing compounds to several times that influx is addressed. The effects of uncertainties in input parameters, including reaction rate coefficients, cross sections, solar fluxes, and boundary conditions, are evaluated using a Monte Carlo method in which the values of the input parameters are randomly selected. The results are probability distributions for present atmosheric concentrations and for calculated perturbations due to chlorine from fluorocarbons. For more than 300 Monte Carlo runs the calculated ozone perturbation for continued emission of fluorocarbons at today's rates had a mean value of -6.2 percent, with a 1-sigma width of 5.5 percent. Using the same runs but only allowing the cases in which the calculated present atmosphere values of NO, NO2, and ClO at 25 km altitude fell within the range of measurements yielded a mean ozone depletion of -3 percent, with a 1-sigma deviation of 2.2 percent. The model showed a nonlinear behavior as a function of added fluorocarbons. The mean of the Monte Carlo runs was less nonlinear than the model run using mean value of the input parameters.

  5. Understanding the structure of hydrophobic surfactants at the air/water interface from molecular level.

    PubMed

    Zhang, Li; Liu, Zhipei; Ren, Tao; Wu, Pan; Shen, Jia-Wei; Zhang, Wei; Wang, Xinping

    2014-11-25

    Understanding the behavior of fluorocarbon surfactants at the air/water interface is crucial for many applications, such as lubricants, paints, cosmetics, and fire-fighting foams. In this study, molecular dynamics (MD) simulations were employed to investigate the microscopic properties of non-ionic fluorocarbon surfactants at the air/water interface. Several properties, including the distribution of head groups, the distribution probability of the tilt angle between hydrophobic tails with respect to the xy plane, and the order parameter of surfactants, were computed to probe the structure of hydrophobic surfactants at the air/water interface. The effects of the monomer structure on interfacial phenomena of non-ionic surfactants were investigated as well. It is observed that the structure of fluorocarbon surfactants at the air/water interface is more ordered than that of hydrocarbons, which is dominated by the van der Waals interaction between surfactants and water molecules. However, replacing one or two CF2 with one or two CH2 group does not significantly influence the interfacial structure, suggesting that hydrocarbons may be promising alternatives to perfluorinated surfactants. PMID:25358083

  6. Detection of Chamber Conditioning Through Optical Emission and Impedance Measurements

    NASA Technical Reports Server (NTRS)

    Cruden, Brett A.; Rao, M. V. V. S.; Sharma, Surendra P.; Meyyappan, Meyya

    2001-01-01

    During oxide etch processes, buildup of fluorocarbon residues on reactor sidewalls can cause run-to-run drift and will necessitate some time for conditioning and seasoning of the reactor. Though diagnostics can be applied to study and understand these phenomena, many of them are not practical for use in an industrial reactor. For instance, measurements of ion fluxes and energy by mass spectrometry show that the buildup of insulating fluorocarbon films on the reactor surface will cause a shift in both ion energy and current in an argon plasma. However, such a device cannot be easily integrated into a processing system. The shift in ion energy and flux will be accompanied by an increase in the capacitance of the plasma sheath. The shift in sheath capacitance can be easily measured by a common commercially available impedance probe placed on the inductive coil. A buildup of film on the chamber wall is expected to affect the production of fluorocarbon radicals, and thus the presence of such species in the optical emission spectrum of the plasma can be monitored as well. These two techniques are employed on a GEC (Gaseous Electronics Conference) Reference Cell to assess the validity of optical emission and impedance monitoring as a metric of chamber conditioning. These techniques are applied to experimental runs with CHF3 and CHF3/O2/Ar plasmas, with intermediate monitoring of pure argon plasmas as a reference case for chamber conditions.

  7. Cardiac arrhythmias during occupational exposure to fluorinated hydrocarbons.

    PubMed Central

    Antti-Poika, M; Heikkilä, J; Saarinen, L

    1990-01-01

    The effects of occupational exposure to chlorodifluoromethane (FC 22) and dichlorodifluoromethane (FC 12) on cardiac rhythm were examined. The subjects were six men who repaired refrigerators (age 31-56, mean 46 years) and a control group of six plumbers (age 29-54, mean 45 years). Ambulatory electrocardiograms (ECG) were recorded for 24 hours on the day of exposure and on a control day. The ECG tapes were automatically analysed with a Reynolds pathfinder 3 apparatus and all aberrant complexes recorded by the machine were checked. One person read all the tapes without knowing whether or not they were recorded during exposure. The number of ventricular ectopic beats were compared between the day of exposure and the control day and with the tape of the control. In addition, the number of ventricular ectopic beats during exposure was compared with the number occurring during the rest of the day. The concentrations of fluorocarbons were measured in four instances. High peak concentrations of fluorocarbons (1300-10,000 cm3/m3) were measured during refrigerator repair work. No clear connection between fluorocarbons and cardiac arrhythmia was found, although one subject had several ventricular ectopic beats which may have been connected with exposure. PMID:2310718

  8. Detection of Chamber Conditioning Through Optical Emission and Impedance Measurements

    NASA Technical Reports Server (NTRS)

    Cruden, Brett A.; Rao, M. V. V. S.; Sharma, Surendra P.; Meyyappan, Meyya; Arnold, Jim (Technical Monitor)

    2000-01-01

    During oxide etch processes, buildup of fluorocarbon residues on reactor sidewalls can cause run-to-run drift and will necessitate some time for conditioning and seasoning of the reactor. Though diagnostics can be applied to study and understand these phenomena, many of them are not practical for use in an industrial reactor. For instance, measurements of ion fluxes and energy by mass spectrometry show that the buildup of insulating fluorocarbon films on the reactor surface will cause a shift in both ion energy and current in an argon plasma. However, such a device cannot be easily integrated into a processing system. The shift in ion energy and flux will be accompanied by an increase in the capacitance of the plasma sheath. The shift in sheath capacitance can be easily measured by a common commercially available impedance probe placed on the inductive coil. A buildup of film on the chamber wall is expected to affect the production of fluorocarbon radicals, and thus the presence of such species in the optical emission spectrum of the plasma can be monitored as well. These two techniques are employed on a GEC (Gaseous Electronics Conference) Reference Cell to assess the validity of optical emission and impedance monitoring as a metric of chamber conditioning. These techniques are applied to experimental runs with CHF3 and CHF3/O2/Ar plasmas, with intermediate monitoring of pure argon plasmas as a reference case for chamber conditions.

  9. Semifluorinated Alkanes at the Air-Water Interface: Tailoring Structure and Rheology at the Molecular Scale.

    PubMed

    Theodoratou, Antigoni; Jonas, Ulrich; Loppinet, Benoit; Geue, Thomas; Stangenberg, Rene; Keller, Rabea; Li, Dan; Berger, Rüdiger; Vermant, Jan; Vlassopoulos, Dimitris

    2016-04-01

    Semifluorinated alkanes form monolayers with interesting properties at the air-water interface due to their pronounced amphi-solvophobic nature and the stiffness of the fluorocarbons. In the present work, using a combination of structural and dynamic probes, we investigated how small molecular changes can be used to control the properties of such an interface, in particular its organization, rheology, and reversibility during compression-expansion cycles. Starting from a reference system perfluor(dodecyl)dodecane, we first retained the linear structure but changed the linkage groups between the alkyl chains and the fluorocarbons, by introducing either a phenyl group or two oxygens. Next, the molecular structure was changed from linear to branched, with four side chains (two fluorocarbons and two hydrocarbons) connected to extended aromatic cores. Neutron reflectivity at the air-water interface and scanning force microscopy on deposited films show how the changes in the molecular structure affect molecular arrangement relative to the interface. Rheological and compression-expansion measurements demonstrate the significant consequences of these changes in molecular structure and interactions on the interfacial properties. Remarkably, even with these simple molecules, a wide range of surface rheological behaviors can be engineered, from viscous over viscoelastic to brittle solids, for very similar values of the surface pressure. PMID:26978461

  10. Pretreatment of Kapton-coated cable for epoxy adhesion

    SciTech Connect

    Carley, J.F.

    1984-01-09

    Preliminary testing of a new system for protecting bonded strain gages that will be attached to the MFTF magnets indicated falling electrical resistance to ground, attributed to the infiltration of moisture. The most likely infiltration route seemed to be along the Kapton lead cable, which has an outer surface of FEP fluorocarbon resin. Samples of the cable were pretreated with a fluorocarbon etchant, Tetra-Etch, for periods of 10, 25, and 40 s at room temperature, followed by rinsing with demineralized water. The treated ends were embedded in the proposed epoxy sealant, Hysol EA 934, a compound containing 70 wt % of asbestos. The tensile-shear stresses required to pull the wires out of these embedments were measured. Results show that the three levels of treatment are equally effective in raising the bond strength from 377 psi for the untreated cable to about twice that, 763 psi. The 40-s exposure to Tetra-Etch appears to have penetrated the 0.5-mil fluorocarbon coating and attacked the Kapton film and the conductor coatings inside it.

  11. Experimental Study on Evaporation Heat Transfer of Ammonia Flowing inside a Horizontal Internally Spirally Grooved Tube

    NASA Astrophysics Data System (ADS)

    Momoki, Satoru; Arima, Hirofumi; Yamaguchi, Tomohiko; Shigechi, Toru

    This paper presents the experimental results on flow boiling heat transfer of ammonia inside a horizontal internally spirally grooved steel tube with 12mm in averaged inner diameter. Experimental conditions are 40 to 80kg/(m2s) in mass velocity, about 0.7MPa in pressure, and 0 to 20 kW/m2 in heat flux. Measured values on frictional pressure drop in adiabatic condition were correlated by Higashiiue's correlation, which was developed based on the experimental results with fluorocarbon refrigerants. On the measured heat transfer coefficients, very little significant effect of heat flux was found even in the small mass velocity condition, and also smaller influence of mass flux was observed than expected from the forced convection heat transfer theory. The measured heat transfer coefficients were compared with the predicted values by the author's previously developed correlation for fluorocarbon refrigerants,and this equation could not predict heat transfer coefficients of ammonia well. The trends of circumferential distribution of wall temperature in high quality region were different from those observed in the case of fluorocarbon refrigerants. In high quality region, annular mist flow regime appears instead of ordinary annular flow regime.

  12. Surface tension of water in the presence of perfluorocarbon vapors.

    PubMed

    Chernyshev, Vasiliy S; Skliar, Mikhail

    2014-03-28

    Fluorocarbons are highly hydrophobic, biocompatible compounds with a variety of medical applications. Despite significant interest, the study of interfacial properties of fluorocarbons in aqueous systems has received limited attention. In this study, we investigate the influence of perfluoropentane and perfluorohexane vapors on the surface tension of water at room temperature. The results show a substantial decrease in the surface tension of water in the presence of perfluorocarbon vapors. In the investigated range of partial pressures up to the saturation value, a linear correlation between the surface tension and the partial pressure was found. This suggests that an adsorbed perfluorocarbon layer is formed on the surface of water. For comparison, the effect of the perfluorocarbon vapor on the surface tension of methanol was also investigated and a similar dependence was observed. Our results indicate that the stability and dynamic transitions of fluorocarbon colloids, which may be dispersed under physiological conditions as microdroplets, bubbles, or their combination, are likely affected by the composition of liquid and gas phases. PMID:24652374

  13. Fluorinated monolayers at liquid-liquid and liquid-vapor interfaces

    NASA Astrophysics Data System (ADS)

    Zhang, Zhongjian

    Microscopic structure of several fluorinated monolayers at water-vapor and water-oil interfaces were examined using x-ray specular reflectivity and grazing incidence diffraction (GID) techniques. Grazing incidence x-ray diffraction measurements of monolayers of perfluoro-n-eicosane (F(CFsb2)sb{20}F) and F(CFsb2)sb{m}(CHsb2)sb{n}H (denoted as Fsb{m}Hsb{n}) supported at the air-water interface demonstrated that even without the conventional polar head group, the surfactant molecules are capable of forming ordered in-plane structures defined by hexagonal close packing of the fluorinated blocks of adsorbed molecules due to the stronger chain-chain interaction between fluorocarbon chains than the corresponding hydrocarbons. The specular reflectivity data reveals a hydrocarbon-down, fluorocarbon-up orientation for Fsb{12}Hsb{18}. In contrast to the conventional expectation that soluble surfactants form disordered monolayers at the liquid-liquid interface, the studies on a fluoroalcohol (F(CFsb2)sb{10}(CHsb2)sb2OH) monolayer at water-hexane interface indicate that the surfactants are in a close packed hexagonal phase, similar to the in-plane structure of other fluorocarbon molecules at water-air interface. Above a transition temperature the monolayer is in a low density gas phase. Preliminary study shows that hysteresis effect occurs around the transition temperature. The first measurements of microscopic structure at common high interfacial tension liquid-liquid interfaces such as a simple oil-water (hexane-water) interface is also reported. Thermal expansion coefficient measurements indicate subtle structural differences in these monolayers.

  14. Single-column-based absorption process for treating dissolver off-gas

    SciTech Connect

    Eby, R.S.; Little, D.K.; Merriman, J.R.; Stephenson, M.J.

    1982-05-21

    The fluorocarbon absorption process for krypton and xenon removal from dissolver off-gas is based on exploitation of solubility differences which exist among noble gases and other gas-phase constituents in the fluorocarbon solvent dichlorofluoromethane (refrigerant-12). Process performance and reliability have been demonstrated on an engineering scale with over 10 years of pilot plant operation, including testing with /sup 85/Kr, /sup 133/Xe, and /sup 131/I. The culmination of this work is a single-column design which results in a simplified process with improved reliability and lower cost. Data are presented summarizing recent single-column development activities. These include data plots depicting decontamination factor vs feed gas flow rate, DF vs process absorption factor (kG/L), and location of the concentration peak via the solvent flow rate. In general, 99% removal is easily obtainable for Kr, Xe, and CO/sub 2/ while attaining concentration factors on the order of 10/sup 3/ to 10/sup 4/. Further concentration of the Kr product is investigated using solid sorbent and cold trapping technologies. Effective removal of entrained fluorocarbon solvent and CO/sub 2/ from the single-column product stream is demonstrated using 13X and 5A molecular sieves, respectively. Additional separation of Xe is studied using a silver mordenite bed and compared to existing methods using cryogenic charcoal beds or selective cold trap sublimation. Regardless of the method for Xe removal, Kr is ultimately concentrated via a simple cold trap to > 90% purity from a feed gas containing 10 ppM. 14 figures.

  15. Potential halogenated industrial carcinogenic and mutagenic chemicals. II. Halogenated saturated hydrocarbons.

    PubMed

    Fishbein, L

    1979-03-01

    The halogenated saturated hydrocarbons analogously to the previously considered halogenated unsaturated hydrocarbons (Part I) possess considerable utility in a broad spectrum of applications including; solvents, dry-cleaning fluids, refrigerants, fumigants, degreasing agents, propellants and intermediates in the production of other chemicals, textiles and plastics. Methyl chloride, methylene chloride, chloroform, carbon tetrachloride, methyl chloroform, 1,1,2-trichloroethane, hexachloroethane, ethyl chloride and fluorocarbons were reviewed principally in terms of their synthesis (or occurrence), areas of application, stability, distribution, reactivity, levels of exposure, populations at risk, carcinogenicity, mutagenicity and metabolism. PMID:373115

  16. Elaboration of composite and chemically heterogeneous icephobic coatings

    NASA Astrophysics Data System (ADS)

    Arianpour, Faranak

    Atmospheric icing happens when the surfaces of exposed structures are subjected to contact with super-cooled water droplets or snow particles. Ice build-up on overhead transmission and distribution lines may lead to mechanical failure or insulator flashover, sometimes resulting in power outages with major socioeconomic consequences. The present study focused on the preparation of heterogeneous coatings (HCs) with hydro- and icephobic properties presenting a number of advantages, such as easy application, time-saving and low cost. The homo- and HCs were prepared by using different methods such as self-assembly, nanoparticles-based and Plasma-based techniques. Super-hydrophobic coatings with very low wetting hysteresis are also considered to be icephobic. However, even super-hydrophobic coatings can deteriorate during successive icing/de-icing cycles, and this can lead to ice mechanical anchoring since liquid water penetrates the porous surface. Additionally, the cost and complexity involved in the fabrication of such coatings as micro and nano roughness is created, constitute other hurdles. In this study HCs are considered as a coating including hydrocarbons and fluorocarbons, while purely hydrocarbons or fluorocarbons coatings are considered as the homogeneous coatings. It was shown by applying different functions (both C-F and C-H) the surface energy is decreased more compared to applying only one function (C-F or C-H alone). It should be noted that the water molecule orientations at the surfaces of the fluorocarbon and hydrocarbon groups were completely different. As a result, by inducing or creating various disparities (hydrocarbons and fluorocarbons) in terms of energy bonding, and water molecule orientation at the molecular level, the ice-solid interface is weakened. The wettability measurement of the HCs showed higher water contact angle (CA) values and smaller water contact angle hysteresis (CAH) values compared to homogeneous coatings. The most important consequence of HCs preparation, via different methods, was observed in low contact angle hysteresis (CAH) values. The prepared HCs by self assembled monolayers ( SAMs), nanoparticles and "masked" plasma sputtering methods resulted in reducing the ice adhesion strength by factors of ~ 3, ~ 1.7 and ~ 1.3 times, respectively, compared to a polished aluminum sample. The durability of coatings was studied under accelerated aging conditions such as UV degradation, several icing/de-icing cycles and immersion in distilled water and different pH solutions. Consequently, based on results obtained it was observed that the HCs are more stable under accelerated aging conditions compared to homogeneous coatings.

  17. Auger stimulated ion desorption of negative ions via K-capture radioactive decay.

    PubMed

    Verkhoturov, S V; Schweikert, E A; Chechik, V; Sabapathy, R C; Crooks, R M; Parilis, E S

    2001-07-16

    We report on Auger stimulated ion desorption via Coulomb explosion from surface self-assembled alkylthiol and fluorocarbon molecular layers, triggered by K-capture decay of an imbedded radioactive 55Fe atom. The charge state of the ejecta is determined by charge exchange in binary atomic collisions in bulk and electron tunneling outside the solid, as well as by fragmentation of electronically excited molecules or molecular fragments. We describe the first nonbeam experiments documenting positive and abundant negative ion desorption due solely to core electron excitation after radioactive decay. PMID:11461591

  18. Auger Stimulated Ion Desorption of Negative Ions via K -Capture Radioactive Decay

    SciTech Connect

    Verkhoturov, S. V.; Schweikert, E. A.; Chechik, Victor; Sabapathy, Rajaram C.; Crooks, Richard M.; Parilis, E. S.

    2001-07-16

    We report on Auger stimulated ion desorption via Coulomb explosion from surface self-assembled alkylthiol and fluorocarbon molecular layers, triggered by K -capture decay of an imbedded radioactive {sup 55}Fe atom. The charge state of the ejecta is determined by charge exchange in binary atomic collisions in bulk and electron tunneling outside the solid, as well as by fragmentation of electronically excited molecules or molecular fragments. We describe the first nonbeam experiments documenting positive and abundant negative ion desorption due solely to core electron excitation after radioactive decay.

  19. Ground-based spectrometer funded to detect stratospheric change

    SciTech Connect

    Not Available

    1988-07-01

    Funds will be provided by the Fluorocarbon Program Panel of the Chemical Manufacturers association to construct a ground-based spectrometer, which will become part of the international Network for Detection of Stratospheric Change. Millitech Corp., of South Deerfield Mass., will receive $380,000 to build the state-of-the-art microwave spectrometer, which will measure concentrations of the chlorine monoxide radical, CLO, a key chemical species with the potential to destroy ozone in the stratosphere. The spectrometer which will be installed and operated at a high altitude station in France, will complement already existing instruments monitoring other important chemical species.

  20. Methods for study of cardiovascular adaptation of small laboratory animals during exposure to altered gravity. [hypothermia for cardiovascular control and cancer therapy

    NASA Technical Reports Server (NTRS)

    Popovic, V.

    1973-01-01

    Several new techniques are reported for studying cardiovascular circulation in small laboratory animals kept in metabolic chambers. Chronical cannulation, miniaturized membrane type heart-lung machines, a prototype walking chamber, and a fluorocarbon immersion method to simulate weightlessness are outlined. Differential hypothermia work on rat cancers provides localized embedding of radionuclides and other chemotherapeutical agents in tumors and increases at the same time blood circulation through the warmed tumor as compared to the rest of the cold body. Some successful clinical applications of combined chemotherapy and differential hypothermia in skin cancer, mammary tumors, and brain gliomas are described.

  1. Analyses of mixed-hydrocarbon binary thermodynamic cycles for moderate-temperature geothermal resources

    NASA Astrophysics Data System (ADS)

    Demuth, O. J.

    1981-02-01

    Both boiling and supercritical shell-and-tube cycles were considered. The performance of a dual-boiling isobutane cycle supplied by a 280 F hydrothermal resource (corresponding to the 5 MW pilot plant at the Raft River site in Idaho) was selected as a reference. To investigate the effect of resource temperature on the choice of working fluid, several analyses were conducted for a 360 F hydrothermal resource, which is representative of the Heber resource in California. The hydrocarbon working fluids analyzed included methane, ethane, propane, isobutane, isopentane, hexane, heptane, and mixtures of those pure hydrocarbons. For comparison, two fluorocarbon refrigerants were also analyzed.

  2. Atomic Resolution Images of Solid-Liquid Interfaces

    NASA Astrophysics Data System (ADS)

    Giambattista, Brian; McNairy, W. W.; Slough, C. G.; Johnson, A.; Bell, L. D.; Coleman, R. V.; Schneir, J.; Sonnenfeld, R.; Drake, B.; Hansma, P. K.

    1987-07-01

    A scanning tunneling microscope (STM) can provide atomic-resolution images of solids covered with a variety of liquids, including cryogenic fluids, both polar and nonpolar solvents, conductive aqueous solutions, oils, and even greases. This short overview includes images of solids covered with liquid nitrogen, liquid helium, paraffin oil, silicone oil, microscope immersion oil, silicone vacuum grease, fluorocarbon grease, glycerol, and salt water. These images show atoms, charge-density waves, grains in an evaporated metal film, and even corrosion processes as they occur in real time. The future includes not only basic research in surface science but also applied research in lithography, lubrication, catalysis, corrosion, electrochemistry, and perhaps even biology.

  3. Managing greenhouse gas emission in the indian aluminum industry

    NASA Astrophysics Data System (ADS)

    Mahadevan, H.

    2001-11-01

    Fluorocarbons are pollutants that destroy the ozone layer in the upper atmosphere and allow more ultraviolet radiation to reach the surface of the earth. Over-exposure to such radiation damages plants and greatly increases people’s risk of skin cancer. Aluminum refineries and smelters, which consume large amounts of energy, are committed to continuous improvement in greenhouse gas abatement. Although India is under no international pressure to reduce greenhouse gas emissions, the Indian aluminum industry could undertake such a commitment voluntarily. This analysis shows where immediate improvements are possible, and presents a tentative action plan for the industry.

  4. Characterization of elastomeric materials with application to design

    NASA Technical Reports Server (NTRS)

    Bower, Mark V.

    1986-01-01

    Redesign of the Space Shuttle Solid Booster has necessitated re-evaluation of the material used in the field joint O-ring seals. The viscoelastic characteristics of five candidate materials were determined. The five materials are: two fluorocarbon compounds, two nitrile compounds, and a silicon compound. The materials were tested in a uniaxial compression test to determine the characteristic relaxation functions. These tests were performed at five different temperatures. A master material curve was developed for each material from the experimental data. The results are compared to tensile relaxation tests. Application of these results to the design analysis is discussed in detail.

  5. Atomic resolution images of solid-liquid interfaces

    PubMed Central

    Giambattista, Brian; McNairy, W. W.; Slough, C. G.; Johnson, A.; Bell, L. D.; Coleman, R. V.; Schneir, J.; Sonnenfeld, R.; Drake, B.; Hansma, P. K.

    1987-01-01

    A scanning tunneling microscope (STM) can provide atomic-resolution images of solids covered with a variety of liquids, including cryogenic fluids, both polar and nonpolar solvents, conductive aqueous solutions, oils, and even greases. This short overview includes images of solids covered with liquid nitrogen, liquid helium, paraffin oil, silicone oil, microscope immersion oil, silicone vacuum grease, fluorocarbon grease, glycerol, and salt water. These images show atoms, charge-density waves, grains in an evaporated metal film, and even corrosion processes as they occur in real time. The future includes not only basic research in surface science but also applied research in lithography, lubrication, catalysis, corrosion, electrochemistry, and perhaps even biology. Images

  6. Selective protection of poly(tetra-fluoroethylene) from effects of chemical etching

    DOEpatents

    Martinez, Robert J.; Rye, Robert R.

    1991-01-01

    A photolithographic method for treating an article formed of polymeric material comprises subjecting portions of a surface of the polymeric article to ionizing radiation; and then subjecting the surface to chemical etching. The ionizing radiation treatment according to the present invention minimizes the effect of the subseuent chemical etching treatment. Thus, selective protection from the effects of chemical etching can be easily provided. The present invention has particular applicability to articles formed of fluorocarbons, such as PTFE. The ionizing radiation employed in the method may comprise Mg(k.alpha.) X-rays or lower-energy electrons.

  7. The Design and Synthesis of Highly Branched and Spherically Symmetric Fluorinated Oils and Amphiles

    PubMed Central

    Jiang, Zhong-Xing; Yu, Y. Bruce

    2007-01-01

    A new emulsifier design principle, based on concepts borrowed from protein science, is proposed. Using this principle, a class of highly branched and spherically symmetric fluorinated oils and amphiles has been designed and synthesized, for potential applications in the construction of fluorocarbon nanoparticles. The Mitsunobu reaction was employed as the key step for introducing three perfluoro-tert-butoxyl groups into pentaerythritol derivatives with excellent yields and extremely simple isolation procedures. Due to the symmetric arrangement of the fluorine atoms, each fluorinated oil or amphile molecule gives one sharp singlet 19F NMR signal. PMID:18461118

  8. Branched Hydrocarbon Low Surface Energy Materials for Superhydrophobic Nanoparticle Derived Surfaces.

    PubMed

    Alexander, Shirin; Eastoe, Julian; Lord, Alex M; Guittard, Frédéric; Barron, Andrew R

    2016-01-13

    We present a new class of superhydrophobic surfaces created from low-cost and easily synthesized aluminum oxide nanoparticles functionalized carboxylic acids having highly branched hydrocarbon (HC) chains. These branched chains are new low surface energy materials (LSEMs) which can replace environmentally hazardous and expensive fluorocarbons (FCs). Regardless of coating method and curing temperature, the resulting textured surfaces develop water contact angles (θ) of ∼155° and root-mean-square roughnesses (Rq) ≈ 85 nm, being comparable with equivalent FC functionalized surfaces (θ = 157° and Rq = 100 nm). The functionalized nanoparticles may be coated onto a variety of substrates to generate different superhydrophobic materials. PMID:26641156

  9. Fabrication of superhydrophobic surfaces with poly(furfuryl alcohol)/multi-walled carbon nanotubes composites

    NASA Astrophysics Data System (ADS)

    Men, Xue-Hu; Zhang, Zhao-Zhu; Song, Hao-Jie; Wang, Kun; Jiang, Wei

    2008-02-01

    Superhydrophobic films of poly(furfuryl alcohol)/multi-walled carbon nanotubes (PFA/MWNTs) composites have been obtained by using fluorocarbon-modified MWNTs (MWNT-OOCC 7F 15), PFA, and PTFE with a simple preparation method. The prepared films showed both high contact angle and small sliding angle for water droplets. The chemical compositions and microstructures of the resultant film surfaces were also investigated by means of infrared spectroscopy, X-ray photoelectron spectroscopy, and field emission scanning electron microscope, respectively. Both the formed multiscale roughness structures and the lower surface energy play an important role in creating the superhydrophobic surfaces of PFA/MWNTs composites.

  10. Viscoelastic properties of elastomeric materials for O-ring applications

    NASA Technical Reports Server (NTRS)

    Bower, Mark V.

    1989-01-01

    Redesign of the Space Shuttle Solid Rocket Booster necessitated re-evaluation of the material used in the field joint O-ring seals. This research project was established to determine the viscoelastic characteristics of five candidate materials. The five materials are: two fluorocarbon compounds, two nitrile compounds, and a silicon compound. The materials were tested in a uniaxial compression test to determine the characteristic relaxation functions. These tests were performed at five different temperatures. A master material curve was developed for each material from the experimental data. The results of this study are compared to tensile relaxation tests. Application of these results to the design analysis is discussed in detail.

  11. Middle-infrared random lasing of Cr 2+ doped ZnSe, ZnS, CdSe powders, powders imbedded in polymer liquid solutions, and polymer films

    NASA Astrophysics Data System (ADS)

    Kim, C.; Martyshkin, D. V.; Fedorov, V. V.; Mirov, S. B.

    2009-05-01

    Room temperature (RT) middle-infrared (Mid-IR) random lasing of chromium- (Cr) doped ZnSe, ZnS, and CdSe powders, powders imbedded in perfluorocarbon liquid polymer solutions, and fluorocarbon polymer films is reported. Laser active powders were prepared without a stage of bulk crystal growth by annealing of starting chemicals (pure, mixed ZnSe:CrSe; ZnS:CrS; CdSe:CrSe). Mixture of the different semiconductor hosts allows tuning oscillation wavelength from 2240 to 2630 nm.

  12. Thermal chemiluminescence from ?-irradiated polytetrafluoroethylene and its emission mechanism: Kinetic analysis and bond dissociation energy of fluoroperoxide group

    NASA Astrophysics Data System (ADS)

    Yamada, Emi; Noguchi, Tsuyoshi; Akai, Nobuyuki; Ishii, Hiroshi; Satoh, Chikahiro; Hironiwa, Takayuki; Millington, Keith R.; Nakata, Munetaka

    2014-11-01

    Temperature dependence of the time evolution of chemiluminescence intensity from ?-irradiated polytetrafluoroethylene was examined by heating isothermally in the range of 150 and 200 C. Kinetic analysis was carried out to estimate the rate constants, from which the dissociation energy of the Osbnd O bond in the fluoroperoxide group was determined to be 97 4 kJ mol-1, being consistent with the corresponding value for small fluorocarbon model systems obtained by quantum chemical calculations. This strongly supports the emission mechanism [sbnd CF(OOF)sbnd CF2sbnd ? sbnd COsbnd CF2sbnd + OF2 + h?] proposed in our previous paper to explain chemiluminescence from the ?-irradiated polytetrafluoroethylene.

  13. Volcanic contribution of chlorine to the stratosphere: more significant to ozone than previously estimated?

    PubMed

    Johnston, D A

    1980-07-25

    Earlier estimates of the chlorine emission from volcanoes, based upon evaluations of the preeruption magmatic chlorine content, are too low for some explosive volcanoes by a factor of 20 to 40 or more. Degassing of ash erupted during 1976 by Augustine Volcano in Alaska released 525 x 10(6) kilograms of chlorine (+/- 40 percent), of which 82 x 10(6) to 175 x 10(6) kilograms may have been ejected into the stratosphere as hydrogen chloride. This stratospheric contribution is equivalent to 17 to 36 percent of the 1975 world industrial production of chlorine in fluorocarbons. PMID:17831367

  14. Materials resistance to low earth orbit environmental effects

    NASA Technical Reports Server (NTRS)

    Pippin, H. G.; Torre, L. P.; Linton, R. G.; Whitaker, A. F.

    1989-01-01

    A number of flexible polymeric materials have been considered as condidates for protective coatings on Kapton film. These coatings have been tested under a variety of environments, each of which simulates one or more aspects of the low earth orbit space environment. Mass loss rates vs fluence and temperatue, optical properties, and surface characteristics under exposure to the various environments will be presented. Kinetics data on Kapton and other materials is interpreted in terms of bond strengths and relative thermodynamic stabilities of potential products. Activation energy for degradation of Kapton by oxygen atoms was determined to be 30 + or - 5 kJ/mol. Materials tested include silicones, fluorosilicones, fluorophosphazenes, fluorocarbons, and hydrocarbons.

  15. Investigation of test methods, material properties, and processes for solar cell encapsulants. Encapsulation task of the low-cost silicon solar array project

    NASA Technical Reports Server (NTRS)

    1977-01-01

    During this quarter, flat-plate solar collector systems were considered and six basic construction elements were identified: outer coatings, superstrates, pottants, substrates, undercoats, and adhesives. Materials surveys were then initiated to discover either generic classes or/and specific products to function as each construction element. Cost data included in the surveys permit ready evaluation of each material. Silicones, fluorocarbons, glass, and acrylic polymers have the highest inherent weatherability of materials studied to date. Only acrylics, however, combine low costs, environmental resistance, and potential processability. This class will receive particular emphasis.

  16. Mass spectrometric studies of the electrical breakdown of thin polymer films

    NASA Technical Reports Server (NTRS)

    Kendall, B. R. F.; Rohrer, V. S.; Bojan, V. J.

    1986-01-01

    The composition of the neutral particles released during the electrical breakdown of 50-micron and 75-micron insulating films of the type used on spacecraft exteriors investigated experimentally using a time-of-flight mass spectrometer triggered by the breakdown event. The experimental apparatus is described in detail, and the results are presented in photographs. It is found that the particle flux from Teflon FEP and PFA films comprise mainly fluorocarbon fragments, some with mass 350 amu or greater, but the flux from Kapton oxygen-ion-beam treated Kapton, Tefzel, and Mylar comprises mainly molecules of mass 44 amu or less.

  17. The 1980 stratospheric-tropospheric exchange experiment

    NASA Technical Reports Server (NTRS)

    Margozzi, A. P. (Editor)

    1983-01-01

    Data are presented from the Stratospheric-Tropospheric Water Vapor Exchange Experiment. Measurements were made during 11 flights of the NASA U-2 aircraft which provided data from horizontal traverser and samplings in and about the tops of extensive cirrus-anvil clouds produced by overshooting cumulus turrets. Aircraft measurements were made of water vapor, ozone, ambient and cloud top temperature, fluorocarbons, nitrous oxide, nitric acid, aerosols, and ice crystal populations. Balloonsondes were flown about twice daily providing data on ozone, wind fields, pressure and temperature to altitudes near 30 km. Satellite photography provided detailed cloud and cloud top temperature information. Descriptions of individual experiments and detailed compilations of all results are provided.

  18. Hydrodefluorination of fluorobenzene and 1,2-difluorobenzene under mild conditions over rhodium pyridylphosphine and bipyridyl complexes tethered on a silica-supported palladium catalyst

    SciTech Connect

    Yang, H.; Gao, H.; Angelici, R.J.

    1999-06-07

    The C-F bond, which is the strongest bond that carbon can form, is extremely reluctant to coordinate to metal centers and is resistant to chemical attack. Although this lack of fluorocarbon reactivity has frequently been exploited in technological and medical applications, this chemical inertness also translates into environmental persistence since these compounds are quite difficult to degrade. Fluorobenzene and 1,2-difluorobenzene are defluorinated under very mild conditions by H{sub 2}(4 atm) at 70 C in the presence of NaOAc. The heterogeneous catalysts for these reactions contain the rhodium pyridylphosphine and bipyridyl complexes tethered to heterogeneous Pd-SiO{sub 2}.

  19. Ozone depletion, the Greenhouse effect, and climate change. Hearings before the Subcommittee on Environmental Pollution of the Committee on Environment and Public Works, United States Senate, Ninety-Ninth Congress, Second Session, June 10 and 11, 1986

    SciTech Connect

    Not Available

    1986-01-01

    Witnesses at a two-day hearing on the nature and magnitude of possible risks from the greenhouse effect and depletion of the ozone layer and the government's role in addressing these problems included representatives of universities, international environmental and resource institutes and organizations, manufacturers of fluorocarbons, historians, and government agencies. Prompting the hearings was a DOE report on the risks and need for intensive research and international cooperation in the area of environmental policy. Technical presentations were given by experts in atmospheric chemistry and oceanography. Additional material submitted for the record follows the testimony of the 16 witnesses.

  20. Effect of hydraulic fluid (MIL-H-83282) on selected commercial O-ring compounds

    NASA Technical Reports Server (NTRS)

    Wood, T. E.; Stone, W. P.

    1978-01-01

    Acrylonitrile and fluorocarbon compounds were evaluated at various temperatures and time intervals in samples of the fluid obtained from three qualified suppliers. It was concluded that both polymers can function in hydraulic fluids within the conditions defined by this study. Hydraulic fluid from each manufacturer was similar in its effect upon each given O-ring material, with one exception. Similarly, there were no striking differences in the resistance of O-rings of the same generic rubber type when provided by the different manufacturers.

  1. Low-cost encapsulation materials for terrestrial solar cell modules

    NASA Technical Reports Server (NTRS)

    Cuddihy, E. F.; Baum, B.; Willis, P.

    1979-01-01

    The paper presents the findings of material surveys intended to identify low cost materials which could be functional as encapsulants (by 1986) for terrestrial solar cell modules. Economic analyses have indicated that in order to meet the low cost goal of $2.70 per sq m, some or all of the following material technologies must be developed or advanced: (1) UV screening outer covers; (2) elastomeric acrylics; (3) weatherproofing and waterproofing of structural wood and paper products; (4) transparent UV stabilizers for the UV-sensitive transparent pottants; and (5) cost-effective utilization of silicone and fluorocarbon materials.

  2. Factors affecting the sticking of insects on modified aircraft wings

    NASA Technical Reports Server (NTRS)

    Yi, O.; Chan, R.; Eiss, N. S.; Pingali, U.; Wightman, J. P.

    1988-01-01

    The adhesion of insects to aircraft wings is studied. Insects were collected in road tests in past studies and a large experimental error was introduced caused by the variability of insect flux. The presence of such errors has been detected by studying the insect distribution across an aluminum-strip covered half-cylinder mounted on the top of a car. After a nonuniform insect distribution (insect flux) was found from three road tests, a new arrangement of samples was developed. The feasibility of coating aircraft wing surfaces with polymers to reduce the number of insects sticking onto the surfaces was studied using fluorocarbon elastomers, styrene butadiene rubbers, and Teflon.

  3. Fluorinated microemulsions: A study of the phase behavior and structure

    SciTech Connect

    LoNostro, P.; Choi, S.M.; Chen, S.H.; Ku, C.Y.

    1999-06-24

    Fluorinated surfactants have been studied for their peculiar property to form micellar aggregates in water and oils (hydrocarbons or fluorocarbons) and to produce stable microemulsions. Because of their capacity to dissolve large amounts of gases (such as oxygen and carbon dioxide) and for their characteristic physicochemical properties, fluorocarbons have been tested for specific medical purposes, and their microemulsions are among the most promising candidates for the production of suitable blood substitutes and other biocompatible fluids. The authors have synthesized a new partially fluorinated nonionic surfactant, namely, F(CF{sub 2}){sub 7}-CO-(OCH{sub 2}CH{sub 2}){sub 7.2}OCH{sub 3} (I), that forms stable microemulsions with water and perfluorocarbons such as perfluorooctane (PFO). In this paper the authors describe for the first time the phase behaviors of perfluorooctanoic acid (PFOA) in water/PFH and in water/PFO, and that of ester I in water/PFO. Small-angle neutron-scattering (SANS) experiments provide a detailed description of the microstructure of the H{sub 2}O/PFO/PFOA ternary system.

  4. Characterization of radical production mechanism in CHF3 and CF4 inductively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Wang, Yaping; Zhao, Shuxia; PSEG Team

    2015-09-01

    Inductively coupled fluorocarbon (fc) plasmas are widely used in Si /SiO2 etching industry as they provide active radicals which are reactive to the Si or SiO2 materials. It is well known that CHF3 plasma has relatively low density ratio of F vs. CFx radicals and hence high etching selectivity, as compared with the CF4 , due to the fact that one F is replaced by H in CHF3 molecules and H can abstract F from fluorocarbon radicals to form HF. However, for now, much elaborate details are still missed in the literature. Therefore in this work, a fluid model is used to characterize the radical production components in these two different fc plasmas. The fluid model includes continuity and energy equations for electrons, continuity and momentum equations for ions and continuity equations for radicals. An electromagnetic model is used to calculate the electric field which is generate by coupling coil current and Poisson equation is used to calculate the static field within the plasma. The model predicts the electron density, ion density and radical density of CHF3 plasma. For now the simulations of CF4 plasma are still under construction. We expect to compare the different radical production mechanisms in the CHF3 and CF4 plasma sources in new future.

  5. Preparation and cell growth inhibitory activity of [PtR(2)L(2)] (R=polyfluorophenyl, L(2)=diene, cyclohexane-1,2-diamine (chxn) or cis-(dimethyl sulfoxide)(2)) and the X-ray crystal structure of [Pt(C(6)F(5))(2)(cis-chxn)].

    PubMed

    Cullinane, Carleen; Deacon, Glen B; Drago, Penny R; Hambley, Trevor W; Nelson, Keith T; Webster, Lorraine K

    2002-04-28

    A range of [PtR(2)(chxn)] (R=C(6)F(5), o-HC(6)F(4), p-HC(6)F(4), p-MeOC(6)F(4) or 3,5-H(2)C(6)F(3); chxn=cyclohexane-1,2-diamine) and cis-[PtR(2)(dmso)(2)] (R=C(6)F(5), p-HC(6)F(4) or p-MeOC(6)F(4); dmso=dimethyl sulfoxide) complexes have been prepared from the corresponding [PtR(2)(diene)] (diene=cis,cis-cycloocta-1,5-diene (cod), hexa-1,5-diene (hex), norbornadiene (nbd) or dicyclopentadiene (dcy)) derivatives and have been spectroscopically characterized. A representative crystal structure of [Pt(C(6)F(5))(2)(cis-chxn)] was determined and shows a slightly distorted square planar geometry for platinum with chxn virtually perpendicular to the coordination plane. The biological activity against L1210 and L1210/DDP cell lines of these compounds together with the behaviour of other organoplatinum complexes, [PtR(2)L(2)] (L(2)=ethane-1,2-diamine (en) or cis-(NH(3))(2)) have been determined. Despite the use of relatively inert fluorocarbon anions as leaving groups, moderate-high cell growth inhibitory activity is observed. None of the fluorocarbon complexes displayed any cross resistance with cisplatin. PMID:12062134

  6. Atomic Oxygen Effects on Seal Leakage

    NASA Technical Reports Server (NTRS)

    Christensen, John R.; Underwood, Steve D.; Kamenetzky, Rachel R.; Vaughn, Jason A.

    1999-01-01

    Common Berthing Mechanism (CBM provides the structural interface between separate International Space Station (ISS) elements, such as the Laboratory and Node modules. The CBM consists of an active and a passive half that join together with structural bolts. The seal at this interface is the CBM-to-CBM molded seal. The CBM-to-CBM interface is assembled on orbit, thus the seals can be exposed to the space environment for up to 65 hours. Atomic Oxygen/Vacuum Ultraviolet radiation (AO/VUV) in space is a potential hazard to the seals. Testing was conducted to determine the effect on leakage of the CBM-to-CBM seal material exposed to AO/VUV. The sealing materials were S383 silicone and V835 fluorocarbon material. Control samples, which were not exposed to the AO/VUV environment, were used to ensure that ff any changes in leakage occurred, they could be attributed to the AO/VUV exposure. After exposure to the AO/VUV environment the leakage increase was dramatic for the fluorocarbon. This testing was a major contributing factor in selecting silicone as the CBM-to-CBM seal material.

  7. BAC-MP4 Predictions of thermochemical data for C{sub 1} and C{sub 2} stable and radical hydrofluorocarbons and oxidized hydrofluorocarbons

    SciTech Connect

    Zachariah, M.R.; Burgess, D.R. Jr.; Tsang, W.; Westmoreland, P.R.; Melius, C.F.

    1996-05-23

    An ab initio bond additivity corrected quantum chemistry procedure has been applied to the development of a data base for thermochemistry of C/H/F/O species. This information has been used to construct a chemical kinetic mechanism for the prediction of the behavior of fluorocarbons as flame suppressants, with clear applications to plasma and atmospheric chemistry as well. Bond additivity corrected (BAC) Moller-Plesset fourth-order perturbation theory (MP4) calculations have been performed to obtain a large body of thermochemical data on about 100 closed and open shelled fluorocarbon species. For about 70 of these species, literature values for enthalpies of formation were available for comparison to the calculated values. The average difference between the calculated and literature values was about 9 kJ/mol. The results indicate that the BAC-MP4 procedure can provide energies that are comparable in accuracy to most experimentally derived values, at lower computational costs relative to other more computationally expensive ab initio molecular orbital methods. This work provides a substantial data base of thermochemical data for fluorinated hydrocarbons constructed in a self-consistent manner. 41 refs., 2 figs., 10 tabs.

  8. Possible atmospheric lifetimes and chemical reaction mechanisms for selected HCFCs, HFCs, CH3CCl3, and their degradation products against dissolution and/or degradation in seawater and cloudwater

    NASA Technical Reports Server (NTRS)

    Wine, P. H.; Chameides, W. L.

    1990-01-01

    For a wide variety of atmospheric species including CO2, HNO3, and SO2, dissolution in seawater or cloudwater followed by hydrolysis or chemical reaction represents a primary pathway for removal from the atmosphere. In order to determine if this mechanism can also remove significant amounts of atmospheric chlorofluorocarbons (HCFC's), fluorocarbons (HFC's), and their degradation products, an investigation was undertaken as part of the Alternative Fluorocarbons Environmental Acceptability Study (AFEAS). In this investigation, the rates at which CHCl2CF3 (HCFC-123), CCl2FCH3 (HCFC-141b), CClF2CH3 (HCFC-142b), CHClF2 (HCFC-22), CHClFCF3 (HCFC-124) CH2FCF3 (HFC-134a) CHF2CH3 (HFC-152a), CHF2CF3 (HFC-125), and CH3CCl3 can be dissolved in the oceans and in cloudwater were estimated from the species' thermodynamic and chemical properties using simple mathematical formulations to simulate the transfer of gases from the atmosphere to the ocean or cloudwater. The ability of cloudwater and rainwater to remove gas phase degradation products of these compounds was also considered as was the aqueous phase chemistry of the degradation products. The results of this investigation are described.

  9. Antisoiling technology: Theories of surface soiling and performance of antisoiling surface coatings

    NASA Astrophysics Data System (ADS)

    Cuddihy, E. F.; Willis, P. B.

    1984-11-01

    Physical examination of surfaces undergoing natural outdoor soiling suggests that soil matter accumulates in up to three distinct layers. The first layer involves strong chemical attachment or strong chemisorption of soil matter on the primary surface. The second layer is physical, consisting of a highly organized arrangement of soil creating a gradation in surface energy from a high associated with the energetic first layer to the lowest possible state on the outer surfce of the second layer. The lowest possible energy state is dictated by the physical nature of the regional atmospheric soiling materials. These first two layers are resistant to removal by rain. The third layer constitutes a settling of loose soil matter, accumulating in dry periods and being removed during rainy periods. Theories and evidence suggest that surfaces that should be naturally resistant to the formation of the first two-resistant layers should be hard, smooth, hydrophobic, free of first-period elements, and have the lowest possible surface energy. These characteristics, evolving as requirements for low-soiling surfaces, suggest that surfaces or surface coatings should be of fluorocarbon chemistry. Evidence for the three-soil-layer concept, and data on the positive performance of candidate fluorocarbon coatings on glass and transparent plastic films after 28 months of outdoor exposure, are presented.

  10. Evaluations of candidate encapsulation designs and materials for low-cost silicon photovoltaic arrays

    NASA Technical Reports Server (NTRS)

    Gaines, G. B.; Carmichael, D. C.; Sliemers, F. A.; Brockway, M. C.; Bunk, A. R.; Nance, G. P.

    1978-01-01

    Three encapsulation designs for silicon photovoltaic arrays based on cells with silk-screened Ag metallization have been evaluated: transparent polymeric coatings over cells laminated between two films or sheets of polymeric materials; cells adhesively bonded to a glass cover with a polymer pottant and a glass or other substrate component. Silicone and acrylic coatings were assessed, together with acrylic sheet, 0.635 mm fiberglass-reinforced polyester sheet, 0.102 mm polycarbonate/acrylic dual-layer film, 0.127 mm fluorocarbon film, soda-lime glass, borosilicate glass, low-iron glass, and several adhesives. The encapsulation materials were characterized by light transmittance measurements, determination of moisture barrier properties and bond strengths, and by the performance of cells before and after encapsulation. Silicon and acrylic coatings provided inadequate protection. Acrylic and fluorocarbon films displayed good weatherability and acceptable optical transmittance. Borosilicate, low-iron and soda-lime-float glasses were found to be acceptable candidate encapsulants for most environments.

  11. A study of the cardiac effects of bromochlorodifluoromethane (halon 1211) exposure during exercise

    SciTech Connect

    Kaufman, J.D.; Morgan, M.S.; Marks, M.L.; Greene, H.L.; Rosenstock, L. )

    1992-01-01

    Bromochlorodifluoromethane (halon 1211, a fire extinguisher), like other fluorocarbons, has been linked with ventricular arrhythmias and myocardial depression. Ten healthy firefighters, aged 40-50, were exposed to 1,000 ppm halon while exercising, in a double-blind, placebo-controlled crossover experiment, and were monitored during and after exposure. Complex ectopy (ventricular couplets and idioventricular rhythm) occurred in two subjects with halon, but none with placebo. One subject had 49.5 ventricular premature beats (VPB)/hour during the period of halon exposure and subsequent 8 hours and only 8.7 VPB/hour during the same period of placebo. In addition, 8 of the 10 subjects had a smaller systolic blood pressure rise during exercise with halon than with placebo. None of the observed differences was statistically significant. These results are consistent with findings in other investigations, suggesting that occupational fluorocarbon exposures may be cardiotoxic in certain individuals, although the small sample sizes used in this and other studies have resulted in limited statistical power to demonstrate this effect.

  12. Theoretical prediction of thermochemistry and kinetics of flurocarbons

    SciTech Connect

    Zachariah, M.R.; Burgess, D. Jr.; Tsang, W.

    1995-12-31

    An ab-initio quantum chemistry procedure has been applied to developing a database for thermochemistry and kinetics of C/H/F/O species. This information has been used to construct a chemical kinetic mechanism for the predication of fluorocarbon combustion. Bond-additivity corrected (BAC) Mollet-Plesset many-body perturbation theory (MP4) calculations have been performed to obtain a large body of thermochemical data (over 110 species) on both closed-and-open shell fluorocarbon species. The method relies on the use of ab-initio molecular orbital theory and an energy correction procedure (BAC) applied to each type of chemical bond in the molecule. In addition, data on transition state structures for reactions have also been generated and rate constants based on RRKM analysis have been derived. Comparisons between theory and experiment will be shown for both the thermochemical and kinetic information as well as a discussion of the power and limitations of this procedure in light of other available methods.

  13. Characterization method of hydrophobic anti-icing coatings.

    PubMed

    Morita, Katsuaki; Sakaue, Hirotaka

    2015-11-01

    For anti-icing, supercooled water should be removed before frozen onto the contact surface. We use a hydrophobic coating for anti-icing and introduce the static- and dynamic-evaluation methods. The methods describe the contact surface between the hydrophobic surface and a supercooled-water droplet. The former is based on the contact angle, and the latter is based on the sliding angle. The temperature factor is included in these models to evaluate the hydrophobic coating under the supercooled conditions. Four hydrophobic coatings are experimentally evaluated based on the static- and dynamic evaluation methods: C1-C3 (commercial fluorocarbon coatings), and Jaxa coating (original fluorocarbon coating). These are evaluated under the supercooled conditions of -10 to 0 °C. The static-evaluation shows variations in the temperature. However, change in the contact angle by the temperature is relatively small compared to that of the sliding angle for the dynamic evaluation. Only C3 and Jaxa coatings are tolerant to the sliding angle under the supercooled conditions tested. The dynamic evaluation shows that even if the coating is hydrophobic, the dynamic evaluation should be included to understand the characteristic of removal for a supercooled-water droplet. PMID:26628173

  14. Uv protective coatings for heliostats and the plastic dome. Final technical report

    SciTech Connect

    Baum, B.; Bansleben, E.; McGrath, P.

    1981-11-01

    Fluorocarbon and acrylic coatings and films were explored as a means of preventing uv degradation of: (1) the polyester (Petra A) film used in the heliostat dome, (2) the first surface silvered polyester (Melinex O) heliostat, (3) the first surface silvered float glass heliostat, as well as (4) and with other coatings to prevent silver spotting of the back surface of a superstrate, second surface heliostat mirror. Uv stabilization systems were developed and tested. The coated or laminated structures were evaluated for adhesion, resistance to high humidity and acid vapor degradation, percent transmittance/ reflectance, water spotting (for case 4 above), and uv stability under the RS-4 Sunlamp (wet and dry). Promising materials were subjected to accelerated outdoor exposure at Desert Sunshine Testing (DSET) in Arizona. Specific uv stabilized acrylic coatings and/or acrylic or fluorocarbon films offered some protection for the Petra A, silvered Melinex O and first surface silvered float glass against weathering, or in case 4 moisture, degradation. However, no system was satisfactory for long term outdoor weathering. Phenoxy primers showed initial promise for back surface protection against silver spotting but require further in depth study.

  15. Detection of Chamber Conditioning by CF4 in the GEC Cell

    NASA Technical Reports Server (NTRS)

    Cruden, Brett A.; Rao, M. V. V. S.; Sharma, S. P.; Meyyappan, M.; Arnold, James (Technical Monitor)

    2001-01-01

    During oxide etch processes, buildup of fluorocarbon residues on reactor sidewalks can cause to drift and will necessitate time for conditioning and cleaning of the reactor. Various measurements in CF4 and Ar plasmas are made in an attempt to identify a metric able to indicate the chamber condition. Mass spectrometry and a Langmuir probe shows that the buildup of fluorocarbon films on the reactor surface causes a decrease in plasma floating potential, plasma potential, and ion energy in argon plasmas. This change in floating potential is also observed in CF4 plasma operation, and occurs primarily during the first hour and a half of plasma operation. A slight rise in electron density is also observed in the argon plasmas. Because the change is seen in an argon plasma, it is indicative of altered physical, not chemical, plasma-surface interactions. Specifically, the insulating films deposited on metal surfaces alter the electromagnetic fields seen by the plasma, affecting various parameters including the floating potential and electron density. An impedance probe placed on the inductive coil shows a slight reduction in plasma impedance due to this rising electron density. The optical emission of several species, including CF, C2, atomic Si and atomic C, is also monitored for changes in density resulting from the buildup of film on the chamber wall. Changes in the optical emission spectrum are comparable to the noise levels in their measurement.

  16. Antisoiling technology: Theories of surface soiling and performance of antisoiling surface coatings

    NASA Technical Reports Server (NTRS)

    Cuddihy, E. F.; Willis, P. B.

    1984-01-01

    Physical examination of surfaces undergoing natural outdoor soiling suggests that soil matter accumulates in up to three distinct layers. The first layer involves strong chemical attachment or strong chemisorption of soil matter on the primary surface. The second layer is physical, consisting of a highly organized arrangement of soil creating a gradation in surface energy from a high associated with the energetic first layer to the lowest possible state on the outer surfce of the second layer. The lowest possible energy state is dictated by the physical nature of the regional atmospheric soiling materials. These first two layers are resistant to removal by rain. The third layer constitutes a settling of loose soil matter, accumulating in dry periods and being removed during rainy periods. Theories and evidence suggest that surfaces that should be naturally resistant to the formation of the first two-resistant layers should be hard, smooth, hydrophobic, free of first-period elements, and have the lowest possible surface energy. These characteristics, evolving as requirements for low-soiling surfaces, suggest that surfaces or surface coatings should be of fluorocarbon chemistry. Evidence for the three-soil-layer concept, and data on the positive performance of candidate fluorocarbon coatings on glass and transparent plastic films after 28 months of outdoor exposure, are presented.

  17. Design and chemical synthesis of iodine-containing molecules for application to solar-pumped I* lasers

    NASA Technical Reports Server (NTRS)

    Shiner, C. S.

    1986-01-01

    The design and chemical synthesis of new media for solar pumped iodine molecule lasers are explored. In an effort to prepare an iodo fluorocarbon compound absorbing strongly at 300 nm or above, the synthesis of perfluoro allylic iodides was investigated. These compounds furnish especially stable allylic radicals upon photodissociation. The desired red shift is anticipated in the absorption maximum could correlate with increasing radical stability. This expectation was based upon the analysis, previously reported, of the structures and absorption maxima of compounds studied earlier. A previously unknown substance was prepared, a prototypical target molecule, perfluoro-3-iodocyclopent-1-ene. It was obtained by reaction of perfluorocyclopentene with sulfur trioxide under the influence of antimony pentafluoride catalyst, followed by treatment of the resulting allylic fluorosulfonate with sodium iodide in sulfoland solvent. Preliminary data indicate that the absorption maximum for the iodo fluorocarbon is not shifted significantly to longer wavelength. It is not certain whether this result reflects an unexpected influence of the cyclic structure upon the position of the absorption maximum.

  18. Structure-Based Design of Dendritic Peptide Bolaamphiphiles for siRNA Delivery

    PubMed Central

    2015-01-01

    Development of safe and effective delivery vectors is a critical challenge for the application of RNA interference (RNAi)-based biotechnologies. In this study we show the rational design of a series of novel dendritic peptide bolaamphiphile vectors that demonstrate high efficiency for the delivery of small interfering RNA (siRNA) while exhibiting low cytotoxicity and hemolytic activity. Systematic investigation into structure–property relationships revealed an important correlation between molecular design, self-assembled nanostructure, and biological activity. The unique bolaamphiphile architecture proved a key factor for improved complex stability and transfection efficiency. The optimal vector contains a fluorocarbon core and exhibited enhanced delivery efficiency to a variety of cell lines and improved serum resistance when compared to hydrocarbon analogues and lipofectamine RNAiMAX. In addition to introducing a promising new vector system for siRNA delivery, the structure–property relationships and “fluorocarbon effect” revealed herein offer critical insight for further development of novel materials for nucleic acid delivery and other biomaterial applications. PMID:26436138

  19. Amphiphilic crescent-moon-shaped microparticles formed by selective adsorption of colloids.

    PubMed

    Kim, Shin-Hyun; Abbaspourrad, Alireza; Weitz, David A

    2011-04-13

    We use a microfluidic device to prepare monodisperse amphiphilic particles in the shape of a crescent-moon and use these particles to stabilize oil droplets in water. The microfluidic device is comprised of a tapered capillary in a theta (θ) shape that injects two oil phases into water in a single receiving capillary. One oil is a fluorocarbon, while the second is a photocurable monomer, which partially wets the first oil drop; silica colloids in the monomer migrate and adsorb to the interface with water but do not protrude into the oil interface. Upon UV-induced polymerization, solid particles with the shape of a crescent moon are formed; removal of fluorocarbon oil yields amphiphilic particles due to the selective adsorption of silica colloids. The resultant amphiphilic microparticles can be used to stabilize oil drops in a mixture of water and ethanol; if they are packed to sufficient surface density on the interface of the oil drop, they become immobilized, preventing direct contact between neighboring drops, thereby providing the stability. PMID:21417254

  20. Creation of superhydrophobic stainless steel surfaces by acid treatments and hydrophobic film deposition.

    PubMed

    Li, Lester; Breedveld, Victor; Hess, Dennis W

    2012-09-26

    In this work, we present a method to render stainless steel surfaces superhydrophobic while maintaining their corrosion resistance. Creation of surface roughness on 304 and 316 grade stainless steels was performed using a hydrofluoric acid bath. New insight into the etch process is developed through a detailed analysis of the chemical and physical changes that occur on the stainless steel surfaces. As a result of intergranular corrosion, along with metallic oxide and fluoride redeposition, surface roughness was generated on the nano- and microscales. Differences in alloy composition between 304 and 316 grades of stainless steel led to variations in etch rate and different levels of surface roughness for similar etch times. After fluorocarbon film deposition to lower the surface energy, etched samples of 304 and 316 stainless steel displayed maximum static water contact angles of 159.9 and 146.6°, respectively. However, etching in HF also caused both grades of stainless steel to be susceptible to corrosion. By passivating the HF-etched samples in a nitric acid bath, the corrosion resistant properties of stainless steels were recovered. When a three step process was used, consisting of etching, passivation and fluorocarbon deposition, 304 and 316 stainless steel samples exhibited maximum contact angles of 157.3 and 134.9°, respectively, while maintaining corrosion resistance. PMID:22913317

  1. Hydrosomes: optically trapped water droplets as nano-containers

    NASA Astrophysics Data System (ADS)

    Helmerson, Kristian; Reiner, Joseph E.; Crawford, Alice M.; Jofre, Ana M.; Kishore, Rani B.; Goldner, Lori S.; Tang, Jianyong; Greene, Mark E.; Gilson, Michael

    2007-09-01

    We demonstrate a novel technique for creating, manipulating, and combining femtoliter to attoliter volume chemical containers. Possible uses include creating controlled chemical reactions involving small quantities of reagent, and studying the dynamics of single molecules. The containers, which we call hydrosomes, are surfactant stabilized aqueous droplets in a low index-of-refraction fluorocarbon medium. The index of refraction mismatch between the container and fluorocarbon is such that individual hydrosomes can be optically trapped by single focus laser beams, i.e. optical tweezers. Previous work on single molecules usually involved the tethering of the molecule to a surface, in order to interrogate the molecule for an extended period of time. The use of hydrosomes opens up the possibility for studying free molecules, away from any perturbing surface. We show that this is indeed true in the case of quantitative FRET with RNA. Furthermore, we demonstrate the controlled fusion of two hydrosomes for studying reactions, such as DNA binding kinetics, and single molecule dynamics under non-equilibrium conditions. We also show the applicability of our technique in analytical chemistry, such as for molecule identification and sorting.

  2. Plasma etching behavior of Y2O3 ceramics: Comparative study with Al2O3

    NASA Astrophysics Data System (ADS)

    Cao, Yu-Chao; Zhao, Lei; Luo, Jin; Wang, Ke; Zhang, Bo-Ping; Yokota, Hiroki; Ito, Yoshiyasu; Li, Jing-Feng

    2016-03-01

    The plasma etching behavior of Y2O3 coating was investigated and compared with that of Al2O3 coating under various conditions, including chemical etching, mixing etching and physical etching. The etching rate of Al2O3 coating declined with decreasing CF4 content under mixing etching, while that of Y2O3 coating first increased and then decreased. In addition, the Y2O3 coating demonstrated higher erosion-resistance than Al2O3 coating after exposing to fluorocarbon plasma. X-ray photoelectron spectroscopy (XPS) analysis confirmed the formations of YF3 and AlF3 on the Y2O3 and Al2O3 coatings, respectively, which acted as the protective layer to prevent the surface from further erosion with fluorocarbon plasma. It was revealed that the etching behavior of Y2O3 depended not only on the surface fluorination but also on the removal of fluoride layer. To analyze the effect of porosity, Y2O3 bulk samples with high density were prepared by spark plasma sintering, and they demonstrated higher erosion-resistances compared with Y2O3 coating.

  3. On the etching characteristics and mechanisms of HfO2 thin films in CF4/O2/Ar and CHF3/O2/Ar plasma for nano-devices.

    PubMed

    Lim, Nomin; Efremov, Alexander; Yeom, Geun Young; Kwon, Kwang-Ho

    2014-12-01

    The study of etching characteristics and mechanisms for HfO2 and Si in CF4/O2/Ar and CHF3/O2/Ar inductively-coupled plasmas was carried out. The etching rates of HfO2 thin films as well as the HfO2/Si etching selectivities were measured as functions of Ar content in a feed gas (0-50% Ar) at fixed fluorocarbon gas content (50%), gas pressure (6 mTorr), input power (700 W), bias power (200 W), and total gas flow rate (40 sccm). Plasma parameters as well as the differences in plasma chemistries for CF4- and CHF3-based plasmas were analyzed using Langmuir probe diagnostics and 0-dimensional plasma modeling. It was found that, in both gas systems, the non-monotonic (with a maximum at about 15-20% Ar) HfO2 etching rate does not correlate with monotonic changes of F atom flux and ion energy flux. It was proposed that, under the given set of experimental conditions, the HfO2 etching process is affected by the factors determining the formation and decomposition kinetics of the fluorocarbon polymer layer. These factor are the fluxes of CF(x) (x = 1, 2) radicals, O atoms and H atoms. PMID:25971118

  4. Assessment of Public Perception of Greenhouse Gases as Precursor to Climate Change Mitigation in Nigeria

    NASA Astrophysics Data System (ADS)

    Nwankwo, L.

    2013-12-01

    The rising concentrations of both CO2 and Non-CO2 Greenhouse Gases in the earth's atmosphere are leading to global climate change. The need to address this climate change has gained momentum in recent times, and as a result public awareness of such greenhouse gases serves as a precursor to climatic change mitigation strategy. Therefore, this study entails collection of information about public perception of Climate Change and identification of carbon dioxide, methane, fluorocarbons, and aerosols as contributors to climate forcing. The assessment was completed using conventional survey technique applied amid 1000 people in Ilorin metropolis, Nigeria. The results show 34.9%, 23.6%, 4.5%, 12.3% and 0.2% levels of recognition or understanding of climate change, carbon dioxide, methane, fluorocarbons and aerosols respectively. The results reveal that public awareness of climate change is low in the study area, while Non-CO2 Greenhouse Gases as contributor to Climate Change is extremely low compared to CO2. The study is a preliminary effort to elicit public views and therefore, would assist decision makers and enhance communication with the public in the context of Science and Environment Policy.

  5. Effect of different binders on mechanical and ballistic properties of boron - viton based fuel rich propellant

    NASA Astrophysics Data System (ADS)

    Verma, Pankaaj; Bhujbal, J. G.; Ghavate, R. B.; Darekar, S. D.; Singh, R. V.

    2013-06-01

    Boron is a preferred metal in air augmented propulsion because of its very high heat of combustion per unit mass and per unit volume. But oxide layer (B2O3) formed on its surface inhibits the combustion of boron. Use of fluorocarbon binder can be a promising approach for the improved ignition of boron. In the present study Fuel Rich Propellant composition based on Boron / Ammonium Perchlorate / vinylidene fluoride, hexafluoropropylene and tetrafluoroethylene terpolymer (Viton-B) as a fluorocarbon binder is processed. The objective of the study is to improve mechanical and ballistic properties of the propellant; Viton-B is partially replaced by other binders like estane, polymethyl metha acrylate, polystyrene and irostic. The different compositions are tested for mechanical properties like ultimate compressive strength (UCS), % Compression and Modulus by Universal Testing Machine following ASTM standard D695-02A; and ballistic properties like pressure exponent value (`n' value) and rate of burning constant value by strand burner technique. It is observed that as Viton is partially replaced; mechanical properties improve; and ballistic properties decrease. From the results, it is concluded that estane can be used as partial replacement of Viton-B, as value of UCS increases by 27% and burn rate & `n' value is comparable with the full Viton-B binder composition.

  6. Non-contact protein microarray fabrication using a procedure based on liquid bridge formation.

    PubMed

    Hartmann, Michael; Sjödahl, Johan; Stjernström, Mårten; Redeby, Johan; Joos, Thomas; Roeraade, Johan

    2009-01-01

    Contemporary microarrayers of contact or non-contact format used in protein microarray fabrication still suffer from a number of problems, e.g. generation of satellite spots, inhomogeneous spots, misplaced or even absent spots, and sample carryover. In this paper, a new concept of non-contact sample deposition that reduces such problems is introduced. To show the potential and robustness of this pressure-assisted deposition technique, different sample solutions known to cause severe problems or to be even impossible to print with conventional microarrayers were accurately printed. The samples included 200 mg mL(-1) human serum albumin, highly concentrated sticky cell adhesion proteins, pure high-salt cell-lysis buffer, pure DMSO, and a suspension of 5-microm polystyrene beads. Additionally, a water-immiscible liquid fluorocarbon, which was shown not to affect the functionality of the capture molecules, was employed as a lid to reduce evaporation during microarray printing. The fluorocarbon liquid lid was shown to circumvent hydrolysis of water-sensitive activated surfaces during long-term deposition procedures. PMID:19023564

  7. Structure of diblock copolymers in supercritical carbon dioxide and critical micellization pressure

    SciTech Connect

    Triolo, R.; Triolo, A.; Triolo, F.; Steytler, D. C.; Lewis, C. A.; Heenan, R. K.; Wignall, G. D.; DeSimone, J. M.

    2000-04-01

    This paper reports a small angle neutron scattering investigation of micelle formation by fluorocarbon-hydrocarbon block copolymers in supercritical CO{sub 2}(sc-CO{sub 2}) at 65 degree sign C. A sharp unimer-micelle transition is obtained due to the tuning of the solvating ability of sc-CO{sub 2} by profiling pressure, so that the block copolymer, in a semidilute solution, finds sc-CO{sub 2} a good solvent at high pressure and a poor solvent at low pressure. At high pressure the copolymer is in a monomeric state with a random coil structure. However, on lowering the pressure, aggregates are formed with a structure similar to aqueous micelles with the hydrocarbon segments forming the core and the fluorocarbon segments forming the corona of the micelle. This unimer-aggregate transition is driven by the gradual elimination of CO{sub 2} molecules solvating the hydrocarbon segments of the polymer. Comparison of these results with related data on the same polymer at different temperatures indicates that the transition is critically related to the density of the solvent. This suggests the definition of a critical micellization density, to our knowledge a new concept in colloid chemistry. (c) 2000 The American Physical Society.

  8. Control of atomic layer degradation on Si substrate

    SciTech Connect

    Nakamura, Y.; Tatsumi, T.; Kobayashi, S.; Kugimiya, K.; Harano, T.; Ando, A.; Kawase, T.; Hamaguchi, S.; Iseda, S.

    2007-07-15

    To develop 32 nm node devices, the degradation of atomic layers on the surface of Si substrates must be controlled. During the etching of a SiO{sub 2} or Si{sub 3}N{sub 4} hard mask or sidewall, the surface of Si is attended due to exposure to fluorocarbon plasma. The authors have quantitatively evaluated the relationship between the energy of incident ions and the thickness of the fluorocarbon polymer for a CH{sub 2}F{sub 2}/CF{sub 4}/Ar/O{sub 2} plasma in a dual frequency CCP system. At a fixed ion energy the thickness of the damage layer (T{sub d}) basically depended on the thickness of the fluorocarbon polymer (T{sub C-F}). When the T{sub C-F} was changed by controlling the O/CF{sub x} gas ratio, T{sub d} had a minimum thickness under the conditions at balance point: P{sub b}, under which the T{sub C-F} was nearly equal to ion penetration depth: D{sub p}. Using molecular dynamics simulation, reaction around the transition from SiO{sub 2} to Si was clarified. The damage was done to the Si before the SiO{sub 2} was completely removed, and the largest T{sub d} was observed when the SiO{sub 2} was etched off. After that, T{sub C-F} began to increase because there was no longer an outflux of O from SiO{sub 2} and the damage decreased as the unstable SiF{sub x} species in the damaged layer desorbed. Once the T{sub C-F} became thicker than the ion penetration depth, the damaged layer got buried and T{sub d} stopped changing. When the ion penetration depth was controlled to be equal to T{sub C-F} in a steady state under low ion energy conditions, the T{sub d} was reduced to less than 1 nm.

  9. Surface Dipoles: A Growing Body of Evidence Supports Their Impact and Importance.

    PubMed

    Lee, Han Ju; Jamison, Andrew C; Lee, T Randall

    2015-12-15

    Surface dipoles arise from differences in the distribution of electron density of interfacial molecular structures as expressed by charge separation. The direction and magnitude of the associated dipole moments directly impact a variety of interfacial phenomena. For example, the wettability of thin film-coated solid surfaces toward polar contacting liquids can be systematically adjusted by reorienting the direction of an array of interfacial dipoles, while the vector sum total of all of the dipole moments associated with such thin films can be used to tune the work function of a metal. One method of producing such dipole arrays is by coating a surface with a self-assembled monolayer (SAM), which is a thin organic film of amphiphilic adsorbates that spontaneously assemble on a surface. The interfacial properties of SAMs can be menu-selected by choice of adsorbate structure using ω-terminated thiols on gold surfaces as a convenient system for studying and utilizing these properties. In this Account, we describe the impact of an array of oriented surface dipoles upon the interfacial energy of the thin film bearing such an array. Our analysis of these films divides the subject of surface dipole arrays into three types: (1) those directing a well-defined electronegative pole toward the interface, (2) those incorporating an invertable polar group, and (3) those directing a well-defined electropositive pole toward the interface. With regard to the first category, we analyze the impact of permanent dipoles on the wettability of alkanethiolate SAMs generated from adsorbates possessing well-defined transitions between terminal fluorocarbon and underlying hydrocarbon chain segments. The second category covers recent reports of light-responsive SAMs formed from azobenzene-based adsorbates. Finally, the third category explores a unique example of a dipole array that exposes the positive ends of the interfacial dipoles formed from CH3-terminated fluorocarbon tailgroups. Our analysis of the SAMs formed from these carefully crafted adsorbates encompassing several series of fluorocarbon-containing thiols provides support for a conclusion that oriented surface dipoles exert a significant influence on interfacial energetics and wettability. In contrast to the limited distance from the interface that a surface dipole array will have upon contacting liquids, the work function of a thin film reflects the influence of all the polar groups within the film. Therefore, we also explore the change in the substrate work function for n-alkanethiol-modified gold surfaces as a function of molecular length and for other adsorbates as a function of their chemical composition. PMID:26579883

  10. Cardiotoxicity of Freon among refrigeration services workers: comparative cross-sectional study

    PubMed Central

    2009-01-01

    Background Freon includes a number of gaseous, colorless chlorofluorocarbons. Although freon is generally considered to be a fluorocarbon of relatively low toxicity; significantly detrimental effects may occur upon over exposure. The purpose of the present study is to investigate whether occupational exposure to fluorocarbons can induce arterial hypertension, myocardial ischemia, cardiac arrhythmias, elevated levels of plasma lipids and renal dysfunction. Methods This comparative cross-sectional study was conducted at the cardiology clinic of the Suez Canal Authority Hospital (Egypt). The study included 23 apparently healthy male workers at the refrigeration services workshop who were exposed to fluorocarbons (FC 12 and FC 22) and 23 likewise apparently healthy male workers (unexposed), the control group. All the participants were interviewed using a pre-composed questionnaire and were subjected to a clinical examination and relevant laboratory investigations. Results There were no significant statistical differences between the groups studied regarding symptoms suggesting arterial hypertension and renal affection, although a significantly higher percentage of the studied refrigeration services workers had symptoms of arrhythmias. None of the workers had symptoms suggesting coronary artery disease. Clinical examination revealed that the refrigeration services workers had a significantly higher mean pulse rate compared to the controls, though no significant statistical differences were found in arterial blood pressure measurements between the two study groups. Exercise stress testing of the workers studied revealed normal heart reaction to the increased need for oxygen, while sinus tachycardia was detected in all the participants. The results of Holter monitoring revealed significant differences within subject and group regarding the number of abnormal beats detected throughout the day of monitoring (p < 0.001). There were no significant differences detected in the average heart rate during the monitoring period within subject or group. Most laboratory investigations revealed absence of significant statistical differences for lipid profile markers, serum electrolyte levels and glomerular lesion markers between the groups except for cholesterol and urinary β2-microglobulin (tubular lesion markers) levels which were significantly elevated in freon exposed workers. Conclusions Unprotected occupational exposure to chlorofluorocarbons can induce cardiotoxicity in the form of cardiac arrhythmias. The role of chlorofluorocarbons in inducing arterial hypertension and coronary artery diseases is unclear, although significantly elevated serum cholesterol and urinary β2-microglobulin levels raise a concern. PMID:19594908

  11. Synthesis of new high performance lubricants and solid lubricants

    SciTech Connect

    Lagow, Richard J.

    1993-04-08

    In our second year of funding we began the testing phase of a number of new classes of lubricants. Three different testing collaborations have already begun and a fourth one is In the works with Dr. Stephen Hsu of the National Institute of Standards and Technology. Dr. Hsu also plans to test some of the same materials for us that Shell Development is studying. With Dr. Bill Jones of NASA, we are studying the effects of branching an high temperature lubricant properties in perfluoropolyethers, Initially Bill Jones is comparing the lubrication and physical properties of perfluorotetraglyme and the following two spherical perfluoropolyethers, Note that one contains a fluorocarbon chain and the other one contains a fluorocarbon ether chain. The synthesis of these was reported in the last progress report. With Professor Patricia Thiel of Iowa State University, we are working on studies of perfluoromethylene oxide ethers and have prepared a series of four of these polyethers to study in collaboration with her research group. These perfluoromethylene oxide ethers have the best low temperature properties of any known lubricants. Thiel's group is studying their interactions with metals under extreme conditions. Thirdly, we have also begun an Interaction with W. August Birke of Shell Development Company in Houston for whom we have already prepared samples of the chlorine-substituted fluorocarbon polyether lubricants whose structures appear on page 54 of our research proposal. Each of these four structures is thought to have potential as lubricant additives to motor oils. We also have underway syntheses of other fluorine-containing branched ether lubricants. These new materials which are also promising as antifriction additives for motor oils appear ahead of the perfluoro additives as Appendix I to the progress report. Additionally for Birke and Shell Development we have at their request prepared the novel compound perfluoro salicylic acid. This synthesis was suggested by the Shell staff who thought that esters of perfluoro salicylic acid might be an excellent antifriction additive for motor oil fuels. One of the best additives currently used in motor oils is the hydrocarbon ester of salicylic acid.

  12. Plasma-surface interactions of nanoporous silica during plasma-based pattern transfer using C{sub 4}F{sub 8} and C{sub 4}F{sub 8}/Ar gas mixtures

    SciTech Connect

    Hua Xuefeng; Stolz, Christian; Oehrlein, G.S.; Lazzeri, P.; Coghe, N.; Anderle, M.; Inoki, C.K.; Kuan, T.S.; Jiang, P.

    2005-01-01

    We have investigated plasma surface interactions of nanoporous silica (NPS) films with porosities up to 50%, and SiO{sub 2} with C{sub 4}F{sub 8}/Ar discharges used for plasma etching. The pore size was about 2-3 nm for all films. In highly polymerizing plasmas (e.g., pure C{sub 4}F{sub 8} discharges), the porous structure of NPS material favors surface polymerization over etching and porosity-corrected etching rates (CER) were suppressed and lower than SiO{sub 2} etching rate for the same conditions. The etching rates of NPS were dramatically enhanced in ion rich discharges (e.g., C{sub 4}F{sub 8}/90%Ar) and the CER in this case is greater than the SiO{sub 2} etching rate. Both x-ray photoelectron spectroscopy (XPS) and static secondary ion mass spectroscopy (static SIMS) show that fairly thick ({approx}2-3 nm) fluorocarbon layers exist on the NPS surface during C{sub 4}F{sub 8} etching. This layer blocks the direct interaction of ions with the NPS surface and results in a low etching rate. For C{sub 4}F{sub 8}/90%Ar discharges, little fluorocarbon coverage is observed for NPS surfaces and the direct ion surface interaction is significantly enhanced, explaining the enhancement of CER. We can deduce from analysis of angular resolved XPS data that the surface of NPS materials and SiO{sub 2} remain smooth during C{sub 4}F{sub 8} etching. For C{sub 4}F{sub 8}/90%Ar etching, the NPS surfaces became rough. The surface roughening is due to angle-dependent ion etching effects. These surface models were directly verified by the transmission electron microscopy. Depth profiling study of NPS partially etched using C{sub 4}F{sub 8} or C{sub 4}F{sub 8}/90%Ar discharges using dynamic SIMS indicates that the plasma induced modification of NPS was enhanced significantly compared with SiO{sub 2} due to the porous structure, which allows the plasma attack of the subsurface region. The modified layer thickness is related to the overall porosity and dramatically increases for NPS with an overall porosity of 50%. The distinct etching behavior of high porosity NPS ({approx}50%) in fluorocarbon-based discharges relative to NPS material with lower overall porosity is possibly due to interconnected pores, which allow plasma species to more easily penetrate into the subsurface region.

  13. SAXS investigation on aggregation phenomena in supercritical \\chem{CO2}

    NASA Astrophysics Data System (ADS)

    Celso, F. Lo; Triolo, A.; Triolo, F.; Donato, D. I.; Steinhart, M.; Kriechbaum, M.; Amenitsch, H.; Triolo, R.

    2002-06-01

    Synchrotron Small-Angle X-Ray scattering (SAXS) measurements on aggregate formation of a Polyvinyl acetate-b-Perfluoro octyl acrylate (PVAc-b-PFOA) block copolymer in supercritical CO{2} are here reported. Experiments were carried out for a series of different thermodynamic conditions, changing the solvent density by profiling both the pressure at constant temperature and the temperature at constant pressure. This block copolymer and in general fluorocarbon-hydrocarbon di-blocks form aggregates depending on the value of CO{2} density. A sharp transition between monomers dissolved as random coils and micelles characterized by a solvophilic shell and a solvophobic core occurs when the CO{2} density reaches a critical value. Results of critical micellization density (CMD) derived from pressure and temperature ramps experiment along with the comparison with previous SANS results are here reported to give additional experimental support to the solvent density-driven aggregation process.

  14. Metal Surface Decontamination by the PFC Solution

    SciTech Connect

    Hui-Jun Won; Gye-Nam Kim; Wang-Kyu Choi; Chong-Hun Jung; Won-Zin Oh

    2006-07-01

    PFC (per-fluorocarbon) spray decontamination equipment was fabricated and its decontamination behavior was investigated. Europium oxide powder was mixed with the isotope solution which contains Co-60 and Cs-137. The different shape of metal specimens artificially contaminated with europium oxide powder was used as the surrogate contaminants. Before and after the application of the PFC spray decontamination method, the radioactivity of the metal specimens was measured by MCA. The decontamination factors were in the range from 9.6 to 62.4. The spent PFC solution was recycled by distillation. Before and after distillation, the turbidity of PFC solution was also measured. From the test results, it was found that more than 98% of the PFC solution could be recycled by a distillation. (authors)

  15. PFC Decontamination of a Metal Surface and the Recycling of a Spent PFC Solution

    SciTech Connect

    Jung, C.H.; Won, H.J.; Oh, W.Z.; Moon, J.K.; Park, J.H.

    2006-07-01

    PFC (per-fluorocarbon) ultrasonic decontamination behavior of loosely contaminated metal specimens such as a plate, pipe, welding and a crevice specimen in a mixed solution of PFC and an anionic surfactant was investigated. Perfluoroheptane (C{sub 7}F{sub 16}) was used as a PFC ultrasonic media. The contaminants were completely removed for almost all of the tested specimens except for the longest pipe length specimen. For the 6-cm long specimen, 98.5 % of the contaminants were removed. For the recycling of the PFC solution, a distillation test for the spent PFC solution was also performed. The results show that 97.5 % of the PFC was recycled without a loss of the decontamination efficiency. (authors)

  16. Metallic and nonmetallic coatings for ICF targets

    SciTech Connect

    Hendricks, C.D.; Crane, J.K.; Hsieh, E.J.; Meyer, S.F.

    1981-04-17

    Some fusion targets designed to be driven by 0.35 to 1 ..mu..m laser light are glass spheres coated with layers of various materials such as hydrocarbons, fluorocarbons, beryllium, copper, gold, platinum, etc. The glass shell, which is filled with gas, liquid or solid deuterium-tritium fuel, must have remarkably good surface and wall thickness uniformity. Methods for depositing the various materials will be discussed. They include plasma polymerization, electro-deposition, sputtering and evaporation. Many of the difficulties encountered in the coating processes are the result of coating on free spheres with very small radii - 35 to 500 micrometers. Several means of overcoming the problems will be described and experimental results presented.

  17. Determination of oxygen concentrations by luminescence quenching of a polymer-immobilized transition-metal complex

    SciTech Connect

    Bacon, J.R.; Demas, J.N.

    1987-12-01

    Oxygen quenching of the luminescence of the tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) perchlorate immobilized in a silicone rubber is shown to be an accurate and precise method for measuring oxygen concentrations in solutions and in the gas phase. Quenching can be quantitated by either lifetime or intensity quenching measurements. Aqueous strong acids, bases, complexing agents, oxidants, and reductants do not penetrate the hydrophobic polymer and, therefore, do not affect the response. Gaseous interferents, such as H/sub 2/S, anesthetic gases (e.g., N/sub 2/O, halothane), and fluorocarbons do not affect the response. Chlorine and especially SO/sub 2/ are strong, but fully reversible, interferents. A system was developed with a response time of less than 0.2 s, which is adequate for the monitoring of breathing subjects.

  18. Time resolved diagnostics in CF4 / H2 plasmas by electron attachment mass spectrometry and optical emission spectroscopy.

    NASA Astrophysics Data System (ADS)

    Wagner, Hans-Erich; Meichsner, Juergen; Kroutilina, Valja; Lerch, Rene

    2000-10-01

    In the case of a parallel plate symmetrical 50 kHz low pressure discharge in CF4 - H2 mixtures (discharge current 10 - 40 mA, total pressure 10 - 30 Pa , hydrogen admixture 0 - 80 %, closed system) the main stable products (e.g. F_2, CF_4, C_2F_6, C_3F_8) of plasma chemical reactions have been time resolved investigated by the electron attachment mass spectrometry (EAMS), investigating them according their resonant electron attachment cross sections. The EAMS was realised by means of a HAL EQP 300 Hiden Analytical system, extended by the (-) RGA mode. The plasma chemical reaction kinetics is characterised by the time dependent consumption of molecular hydrogen and the production of higher molecular fluorocarbons. These measurements were completed by optical emission spectroscopy of electronic excited species (e.g. atomic fluorine, molecular hydrogen).

  19. Comparison of Hyperthermal Ground Laboratory Atomic Oxygen Erosion Yields With Those in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; Dill, Grace C.; Loftus, Ryan J.; deGroh, Kim K.; Miller, Sharon K.

    2013-01-01

    The atomic oxygen erosion yields of 26 materials (all polymers except for pyrolytic graphite) were measured in two directed hyperthermal radio frequency (RF) plasma ashers operating at 30 or 35 kHz with air. The hyperthermal asher results were compared with thermal energy asher results and low Earth orbital (LEO) results from the Materials International Space Station Experiment 2 and 7 (MISSE 2 and 7) flight experiments. The hyperthermal testing was conducted to a significant portion of the atomic oxygen fluence similar polymers were exposed to during the MISSE 2 and 7 missions. Comparison of the hyperthermal asher prediction of LEO erosion yields with thermal energy asher erosion yields indicates that except for the fluorocarbon polymers of PTFE and FEP, the hyperthermal energy ashers are a much more reliable predictor of LEO erosion yield than thermal energy asher testing, by a factor of four.

  20. Neutron radigoraphy of fluid flow for geothermal energy research

    SciTech Connect

    Bingham, Philip R.; Polsky, Yarom; Anovitz, L.; Carmichael, Justin R.; Bilheux, Hassina Z; Jacobson, David; Hussey, Dan

    2015-01-01

    Enhanced geothermal systems seek to expand the potential for geothermal energy by engineering heat exchange systems within the earth. A neutron radiography imaging method has been developed for the study of fluid flow through rock under environmental conditions found in enhanced geothermal energy systems. For this method, a pressure vessel suitable for neutron radiography was designed and fabricated, modifications to imaging instrument setups were tested, multiple contrast agents were tested, and algorithms developed for tracking of flow. The method has shown success for tracking of single phase flow through a manufactured crack in a 3.81 cm (1.5 inch) diameter core within a pressure vessel capable of confinement up to 69 MPa (10,000 psi) using a particle tracking approach with bubbles of fluorocarbon-based fluid as the “particles” and imaging with 10 ms exposures.

  1. Control of internal and external short circuits in lithium batteries using a composite thermal switch

    NASA Technical Reports Server (NTRS)

    Mcdonald, Robert C.; Pickett, Jerome; Goebel, Franz

    1991-01-01

    A composite material has been developed, consisting of a blend of metal and fluorocarbon particles, which behaves as an electronic conductor at room temperature and which abruptly becomes an insulator at a predetermined temperature. This switching behavior results from the difference in thermal expansion coefficients between the conductive and non-conductive portions of the composite. This material was applied as a thin film between the carbon cathode in Li/SOCl2 cells, and the metallic cathode current collector. Using test articles incorporating this feature it was shown that lithium cells externally heated or internally heated during a short circuit lost rate capability and the ability to overheat well below the melting point of lithium (180 C). Thus, during an internal or external cell short circuit, the potential for thermal runaway involving reactions of molten lithium is avoided.

  2. The PICASSO Dark Matter Experiment

    NASA Astrophysics Data System (ADS)

    Wichoski, Ubi

    2011-12-01

    The PICASSO experiment searches for cold dark matter through the direct detection of weakly interacting massive particles (WIMPs) via their spin-dependent interactions with fluorine at SNOLAB, Sudbury—ON, Canada since 2002. The detection principle is based on the superheated droplet technique; the detectors consist of a gel matrix with millions of liquid droplets of superheated fluorocarbon (C4F10) dispersed in it. Recently, a new setup has been built and installed in the Ladder Lab area at SNOLAB. In the present phase of the experiment the Collaboration is running 4.5-litre detector modules with approximately 85 g of active mass per module. Here, we give an overview of the experiment and discuss the progress in background mitigation, in particular background discrimination in the PICASSO detectors.

  3. Novel direct vision prism and Wollaston prism assembly for diffraction limit applications

    NASA Astrophysics Data System (ADS)

    Ebizuka, Noboru; Yokota, Hideo; Kajino, Fumiyoshi; Kawabata, Koji S.; Iye, Masanori; Sato, Shuji

    2008-07-01

    We propose two types of novel prisms; 1) a direct vision prism with approximately linear angular dispersion as a function of wavelength (Liner dispersion prism: LDP) suitable for a wide range spectrometer, and 2) a novel Wollaston prism assembly (WPA) suitable for a polarizing imager and spectro-polarimeter with a wide wavelength coverage. LDP composes several kinds of glasses or plastics or crystals. Angular dispersion of LDP is enlarged by employment of with some kind of plastic. LDPs, which are employed polycarbonate and Cytop (Amorphous fluorocarbon resin), provide approximately linear angular dispersion in ultraviolet and visible wavelength, respectively. WPA is composed of two or three kinds of Wollaston prism with different birefringent crystals. WPA provides an achromatic angular separation or an angular separation with linear dispersion. These prisms will enable us to achieve a diffraction-limited capability on next generation telescopes of both ground-based and space-borne.

  4. Fluorine Bonding Enhances the Energetics of Protein-Lipid Binding in the Gas Phase

    NASA Astrophysics Data System (ADS)

    Liu, Lan; Jalili, Nobar; Baergen, Alyson; Ng, Simon; Bailey, Justin; Derda, Ratmir; Klassen, John S.

    2014-05-01

    This paper reports on the first experimental study of the energies of noncovalent fluorine bonding in a protein-ligand complex in the absence of solvent. Arrhenius parameters were measured for the dissociation of gaseous deprotonated ions of complexes of bovine β-lactoglobulin (Lg), a model lipid-binding protein, and four fluorinated analogs of stearic acid (SA), which contained (X =) 13, 15, 17, or 21 fluorine atoms. In all cases, the activation energies (Ea) measured for the loss of neutral XF-SA from the (Lg + XF-SA)7- ions are larger than for SA. From the kinetic data, the average contribution of each > CF2 group to Ea was found to be ~1.1 kcal mol-1, which is larger than the ~0.8 kcal mol-1 value reported for > CH2 groups. Based on these results, it is proposed that fluorocarbon-protein interactions are inherently stronger (enthalpically) than the corresponding hydrocarbon interactions.

  5. Manipulating surface wettability and oil absorbency of diatomite depending on processing and ambient conditions

    NASA Astrophysics Data System (ADS)

    Özen, İlhan; Şimşek, Süleyman; Okyay, Gamze

    2015-03-01

    In this study, a diatomite sample, which is a natural inorganic mineral with inherently high water and oil absorption capacity, was subjected to grinding before surface modification. Afterwards, the diatomite surface was modified via facile methods using a fluorocarbon (FC) chemical and stearic acid (SA) in addition to the sol-gel fluorosilanization (FS) process. The water and oil wettability, and oil absorbency properties of the unmodified and modified diatomites were investigated in addition to diatomite characterizations such as chemical content, surface area, particle size distribution, morphology, and modification efficiency. It was revealed that the wettability was changed completely depending on the surface modification agent and the media used, while the oil absorbency property surprisingly did not change. On the other hand, the oil absorbency was worsened by the grinding process, whereas the wettability was not affected.

  6. Electrical Conductance of Hydrophobic Membranes or What Happens Below the Surface

    PubMed Central

    Vlassiouk, Ivan; Rios, Fabian; Vail, Sean A.; Gust, Devens; Smirnov, Sergei

    2008-01-01

    Nanoporous alumina membranes rendered hydrophobic by surface modification via covalent attachment of hydrocarbon or fluorocarbon chains conduct electricity via surface even when the pores are not filled with electrolyte. The resistance is many orders of magnitude higher than for electrolyte filled membranes and does not depend on the electrolyte concentration or pH but it does depend on the type of hydrophobic monolayer and its density. The corresponding surface resistance varies from greater than 1018 Ω/□ to less than 3×109 Ω/□. When the hydrophobic monolayer contains a small proportion of photoactive spiropyran that is insufficient to switch the surface to hydrophilic after spiropyran photoisomerization to the merocyanine form, the membrane resistance also becomes light-dependent with a reversible increase of surface resistance by as much as 15%. Surface conduction is ascribed to hydration and ionization of the alumina surface hydroxyls and the ionizable groups of the hydrophobic surface modifiers. PMID:17542624

  7. Alternative training agents, phase 1. Survey of near-term candidate fire extinguishing agents and predicting properties of halocarbon mixtures, volume 1

    NASA Astrophysics Data System (ADS)

    Nimitz, Jonathan S.; Tapscott, Robert E.; Skaggs, Stephanie R.; Beeson, Harold D.

    1991-02-01

    In this report, 14 compounds are examined as potential near-term candidates for alternative firefighter training agents for streaming applications. This list consists of suitable fluorine-containing compounds (primarily fluorocarbons, hydrofluorocarbons, and hydrochlorofluorocarbons) known to have had significant toxicity testing completed, with bulk production capabilities existing in the past, present, or anticipated near future. Many of these compounds are being produced or considered as replacements for chlorofluorocarbons (CFCs) in refrigeration and foam-blowing applications. The ozone depletion potential, global warming potential, stage of toxicity testing, toxicity, availability, and relative cost of each compound are discussed. Physical and thermodynamic properties and estimated and measured flame suppression concentrations are reported. Those compounds that have low toxicity (with significant testing completed) are available in bulk and have desirable properties are discussed in detail. It is recommended that HCFC-123 be tested both in pure form and in blends as potential replacement training agents. Twelve blends are recommended for fire suppression.

  8. Corrosion of current-collector materials in Li-ion cells

    SciTech Connect

    Braithwaite, J.; Nagasubramanian, G.; Gonzales, A.; Lucero, S.; Cieslak, W.

    1996-12-01

    The primary current-collector materials being used in lithium-ion cells are susceptible to environmental degradation: aluminum to pitting corrosion and copper to environmentally assisted cracking. Pitting occurs at the highly oxidizing potentials associated with the positive-electrode charge condition. However, the pitting mechanism is more complex than that typically observed in aqueous systems in that the pits are filled with a mixed metal/oxide product and exist as mounds or nodules on the surface. Electrochemical impedance was shown to be an effective analytical tool for quantification and verification of visual observations and trends. Two fluorocarbon-based coatings were shown to improve the resistance of Al to localized pitting. Finally, environmental cracking of copper can occur at or near the lithium potential and only if specific metallurgical conditions exist (work hardening and large grain size).

  9. Effects of space radiation on thin polymers and nonmetallics

    NASA Technical Reports Server (NTRS)

    Fogdall, L. B.; Cannaday, S. S.; Slemp, W. S.

    1977-01-01

    Advanced materials for various spacecraft systems in the 1980s and 1990s have been evaluated in situ after exposure to space radiation. Emphasis has been placed on materials having little or no previous base of environmental effects data. Applications ranging from earth orbit to near-sun have been covered. High temperature polymers and composites have been included. Silica composites may offer improved reflectance stability compared with metallized fluorocarbons. Directional reflectance properties of FEP are a function of charged particle energy and flux as well as total exposure fluence and material characteristics. Data obtained on polyimides and polyxylylenes under high temperature radiation exposure conditions will be discussed in the context of near-sun solar sailing and rendezvousing.

  10. Thermodynamic and transport properties of some alternative ozone-safe refrigerants for industrial refrigeration equipment: Study in Belarus and Ukraine

    NASA Astrophysics Data System (ADS)

    Grebenkov, A. J.; Zhelezny, V. P.; Klepatsky, P. M.; Beljajeva, O. V.; Chernjak, Yu. A.; Kotelevsky, Yu. G.; Timofejev, B. D.

    1996-05-01

    The study of several hydrofluorocarbons (HFC) and fluorocarbons (FC) and their binary mixtures that have no ozone-depleting ability is being carried Out in the framework of Belarus National Program. The fluids include HFCs R134a. R152a, R135, and R32, and FC R218. The following properties are being investigated: ( I ) phase equilibrium parameters including the boiling and condensing curve and critical point, thermophysical properties at these parameters, and heat of evaporation: (2) isobaric and isochoric heat capacity, ethalpy, and entropy in the gas and liquid state: (3) speed of sound, thermal conductivity. viscosity, and density in the gas and liquid state: (4) dielectric properties and surface tension: (5) behavior of combined construction materials inside the refrigerant medium: and (6) solubility in compressor oils and other technological characteristics. The series of results obtained by authors during the period 1990 1993 is presented.

  11. Laboratory Studies of Chemical and Photochemical Processes Relevant to Stratospheric Ozone

    NASA Technical Reports Server (NTRS)

    Zahniser, Mark S.; Nelson, David D.; Worsnop, Douglas R.; Kolb, Charles E.

    1996-01-01

    The purpose of this project is to reduce the uncertainty in several key gas-phase kinetic processes which impact our understanding of stratospheric ozone. The main emphasis of this work is on measuring rate coefficients and product channels for reactions of HOx and NOx species in the temperature range 200 K to 240 K relevant to the lower stratosphere. Other areas of study have included infrared spectroscopic studies of the HO radical, measurements of OH radical reactions with alternative fluorocarbons, and determination of the vapor pressures of nitric acid hydrates under stratospheric conditions. The results of these studies will improve models of stratospheric ozone chemistry and predictions of perturbations due to human influences.

  12. The importance of the Montreal Protocol in protecting climate

    PubMed Central

    Velders, Guus J. M.; Andersen, Stephen O.; Daniel, John S.; Fahey, David W.; McFarland, Mack

    2007-01-01

    The 1987 Montreal Protocol on Substances that Deplete the Ozone Layer is a landmark agreement that has successfully reduced the global production, consumption, and emissions of ozone-depleting substances (ODSs). ODSs are also greenhouse gases that contribute to the radiative forcing of climate change. Using historical ODSs emissions and scenarios of potential emissions, we show that the ODS contribution to radiative forcing most likely would have been much larger if the ODS link to stratospheric ozone depletion had not been recognized in 1974 and followed by a series of regulations. The climate protection already achieved by the Montreal Protocol alone is far larger than the reduction target of the first commitment period of the Kyoto Protocol. Additional climate benefits that are significant compared with the Kyoto Protocol reduction target could be achieved by actions under the Montreal Protocol, by managing the emissions of substitute fluorocarbon gases and/or implementing alternative gases with lower global warming potentials. PMID:17360370

  13. Mass spectral study of chlorofluorocarbons (CFCs) and potential alternatives (HCFCs and HFCs).

    PubMed

    Reizian, A; Dat, Y; Rault, S; Robba, M

    1994-10-01

    Owing to high ozone depletion potential of the chlorofluorocarbons (CFCs), the production of such substances has been regulated worldwide by the Montreal Protocol in 1987. There is an urgent need to find other suitable products to replace them and hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) are considered to be the most probable candidates as CFC alternatives. The HCFCs and HFCs are more susceptible to decomposition during use than CFCs because they contain hydrogen. Toxicological data on these alternative fluorocarbons are being developed. A systematic investigation of these compounds has been undertaken to establish the fragmentation patterns. Electron impact mass spectra are reported for HCFCs and HFCs. Fragmentation mechanisms are presented and discussed on the basis of variable energy (11 to 30 eV) spectra. At low ionization energy, it is possible to describe an order of fragmentation for each compound. This may lead to the possibility of classifying them according to characteristic behaviors. PMID:7529163

  14. Electron ionization of open/closed chain isocarbonic molecules relevant in plasma processing: Theoretical cross sections

    NASA Astrophysics Data System (ADS)

    Patel, Umang R.; Joshipura, K. N.; Kothari, Harshit N.; Pandya, Siddharth H.

    2014-01-01

    In this paper, we report theoretical electron impact ionization cross sections from threshold to 2000 eV for isocarbonic open chain molecules C4H6, C4H8, C4F6 including their isomers, and closed chain molecules c-C4H8 and c-C4F8. Theoretical formalism employed presently, viz., Complex Scattering Potential-ionization contribution method has been used successfully for a variety of polyatomic molecules. The present ionization calculations are very important since results available for the studied targets are either scarce or none. Our work affords comparison of C4 containing hydrocarbon versus fluorocarbon molecules. Comparisons of the present ionization cross sections are made wherever possible, and new ionization data are also presented.

  15. The importance of the Montreal Protocol in protecting climate.

    PubMed

    Velders, Guus J M; Andersen, Stephen O; Daniel, John S; Fahey, David W; McFarland, Mack

    2007-03-20

    The 1987 Montreal Protocol on Substances that Deplete the Ozone Layer is a landmark agreement that has successfully reduced the global production, consumption, and emissions of ozone-depleting substances (ODSs). ODSs are also greenhouse gases that contribute to the radiative forcing of climate change. Using historical ODSs emissions and scenarios of potential emissions, we show that the ODS contribution to radiative forcing most likely would have been much larger if the ODS link to stratospheric ozone depletion had not been recognized in 1974 and followed by a series of regulations. The climate protection already achieved by the Montreal Protocol alone is far larger than the reduction target of the first commitment period of the Kyoto Protocol. Additional climate benefits that are significant compared with the Kyoto Protocol reduction target could be achieved by actions under the Montreal Protocol, by managing the emissions of substitute fluorocarbon gases and/or implementing alternative gases with lower global warming potentials. PMID:17360370

  16. Study of toxicological evaluation of fire suppressants and extinguishers

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The application of fluorocarbons as possible candidates for fire extinguishers and/or suppressants in confined spaces (such as spacecraft, aircraft, or submarines) was investigated, with special emphasis on their safety to man since they would be inhaled on an almost continuous basis. Short-term exposure experiments, using various animal species, were devised to look at specific parameters in order to determine which of the candidate compounds were sufficiently non-toxic to warrant long-term investigations. The following physiologic criteria were examined; tissue distribution, fluoride concentration, effect on mitochondria, microsomes, liposomes, and liver cell nuclei, erythrocyte fragility, clinical chemistry values, hematology, pathology, cardiac sensitization, behavioral effects. Various rodent species were used for initial investigations, with non-human primate exposures for Freon 116 which was warranted for negative results on rodents. Various types of exposure chambers were used, including closed dynamic chambers allowing for a recirculating atmosphere.

  17. Krypton retention on solid adsorbents. [Activated alumina; hydrogen mordenite, silver mordenite, sodium mordenite, cerium mordenite-H, cerium mordenite-Na, potassium mordenite-H, potassium mordenite-Na

    SciTech Connect

    Monson, P.R. Jr.

    1982-01-01

    An experimental laboratory program was conducted to develop economical solid adsorbents for the retention of krypton from a dissolver off-gas stream. The study indicates that a solid adsorbent system is feasible and competitive with other developing systems which utilize fluorocarbon absorption nd cryogenic distillation. This technology may have potential applications not only in nuclear fuel reprocessing plants, but also in nuclear reactors and in environmental monitoring. Of the 13 prospective adsorbents evaluated with respect to adsorption capacity and cost, the commercially available hydrogen mordenite was the most cost-effective material at subambient temperatures (-40/sup 0/ to -80/sup 0/C). Silver mordenite has a higher capacity for krypton retention, but is 50 times more expensive than hydrogen mordenite.

  18. Acute inhalation toxicity evaluation of a 93:7 mixture of perfluoro-2-butene and 1-bromopropane, a replacement candidate for ozone depleting substances. Interim report, July--August 1997

    SciTech Connect

    Feldmann, M.L.; Leahy, H.F.; Vinegar, A.

    1997-10-01

    The DoD requires the development of toxicity profiles for chemical substitute candidates proposed to replace ozone depleting substances such as chloro- and fluorocarbons and halons. A 93:7 mixture of perfluoro-2-butene and 1-bromopropane was identified as a possible replacement candidate for ozone-depleting fire extinguishants. An acute inhalation toxicity test utilizing male and female Fischer 344 rats was performed on this test material. No deaths occurred in any of the rats exposed to 5.3 mg/L of the 93:7 perfluoro-2-butene and 1-bromopropane mixture. Body weights of male and female rats during the subsequent 14-day observation period were unaffected by treatment. The test material did not produce acute toxicity via the inhalation route.

  19. Monolithic polymer microlens arrays with high numerical aperture and high packing density.

    PubMed

    Jung, Hyukjin; Jeong, Ki-Hun

    2015-02-01

    This work reports a novel method for monolithic fabrication of high numerical aperture polymer microlens arrays (high-NA MLAs) with high packing density (PD) at wafer level. The close-packed high-NA MLAs were fabricated by incorporating conformal deposition of ultrathin fluorocarbon nanofilm and melting the cylindrical polymer islands. The NA and PD of hemispherical MLAs with a hexagonal arrangement increase up to 0.6 and 89%, respectively. The increase of NA enhances the lens transmission securing the beam width down to 1.1 μm. The close-packed high-NA MLAs enable high photon collection efficiency with signal-to-noise ratio greater than 50:1. PMID:25612820

  20. High DNA-Binding Affinity and Gene-Transfection Efficacy of Bioreducible Cationic Nanomicelles with a Fluorinated Core.

    PubMed

    Wang, Long-Hai; Wu, De-Cheng; Xu, Hang-Xun; You, Ye-Zi

    2016-01-11

    During the last two decades, cationic polymers have become one of the most promising synthetic vectors for gene transfection. However, the weak interactions formed between DNA and cationic polymers result in low transfection efficacy. Furthermore, the polyplexes formed between cationic polymers and DNA generally exhibit poor stability and toxicity because of the large excess of cationic polymer typically required for complete DNA condensation. Herein, we report the preparation of a novel class of bioreducible cationic nanomicelles by the use of disulfide bonds to connect the cationic shell to the fluorocarbon core. These bioreducible nanomicelles form strong interactions with DNA and completely condense DNA at an N/P ratio of 1. The resulting nanomicelle/DNA polyplexes exhibited high biocompatibility and performed very effectively as a gene-delivery system. PMID:26586102

  1. ICP Reactor Modeling: CF4 Discharge

    NASA Technical Reports Server (NTRS)

    Bose, Deepak; Govindan, T. R.; Meyyappan, M.

    1999-01-01

    Inductively coupled plasma (ICP) reactors are widely used now for etching and deposition applications due to their simpler design compared to other high density sources. Plasma reactor modeling has been playing an important role since it can, in principle, reduce the number of trial and error iterations in the design process and provide valuable understanding of mechanisms. Fluorocarbon precursors have been the choice for oxide etching. We have data available on CF4 from our laboratory. These are current voltage characteristics, La.ngmuir probe data, UV-absorption, and mass spectrometry measurements in a GEC-ICP reactor. We have developed a comprehensive model for ICP reactors which couples plasma generation and transport and neutral species dynamics with the gas flow equations. The model has been verified by comparison with experimental results for a nitrogen discharge in an ICP reactor. In the present work, the model has been applied to CF4 discharge and compared to available experimental data.

  2. Manufacture and quality control of interconnecting wire hardnesses, Volume 1

    NASA Technical Reports Server (NTRS)

    1972-01-01

    A standard is presented for manufacture, installation, and quality control of eight types of interconnecting wire harnesses. The processes, process controls, and inspection and test requirements reflected are based on acknowledgment of harness design requirements, acknowledgment of harness installation requirements, identification of the various parts, materials, etc., utilized in harness manufacture, and formulation of a typical manufacturing flow diagram for identification of each manufacturing and quality control process, operation, inspection, and test. The document covers interconnecting wire harnesses defined in the design standard, including type 1, enclosed in fluorocarbon elastomer convolute, tubing; type 2, enclosed in TFE convolute tubing lines with fiberglass braid; type 3, enclosed in TFE convolute tubing; and type 5, combination of types 3 and 4. Knowledge gained through experience on the Saturn 5 program coupled with recent advances in techniques, materials, and processes was incorporated.

  3. Nano-coatings on carbon structures for interfacial modification

    NASA Astrophysics Data System (ADS)

    Pulikollu, Rajasekhar V.

    Surface modification of materials is a rapidly growing field as structures become smaller, more integrated and complex. It opens up the possibility of combining the optimum bulk properties of a material with optimized surface properties such as enhanced bonding, corrosion resistance, reactivity, stress transfer, and thermal, optical or electrical behavior. Therefore, surface functionalization or modification can be an enabling step in a wide variety of modern applications. In this dissertation several surface modification approaches on carbon foam and carbon nano-fibers will be discussed. These are recently developed sp2 graphitic carbon based structures that have significant potential in aerospace, automotive and thermal applications. Influence of surface modification on composite formation and properties have also been investigated. Two types of property changes have been investigated: one for enhancing the surface reactivity and another for surface inertness. Characterization techniques such as X-ray Photoelectron Spectroscopy (XPS), Atomic Force Microscopy (AFM), Contact Angle Measurement, Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and mechanical testing are used in this study to find out the influence of these coatings on surface composition, chemistry and morphology. Mechanical testing has been performed on composites and stand alone foam to study the influence of surface modification on physical and mechanical properties of the composite materials. The effectiveness of these coatings on metallic/graphite interface has also been investigated for metal-matrix composite related applications. Additionally, the influence of plasma coatings on nucleation and growth of nanotubes on larger carbon structures (to produce multiscale, multifunctional materials) have also been studied. It is seen that the liquid phase activation treatment introduces oxygen functional groups on the surface, but may cause severe enough degradation that damages the ligaments and cell walls of carbon foam. This results in higher elastic modulus but lower strength. So, to get any benefit from such approaches the optimization window may be very narrow and marginal in controllability. An alternative solution would be to synthesize ultra thin film coatings without etching the surfaces. It is observed that plasma assisted coatings having thickness in the range of few nanometers (4-5nm) are completely covering the graphite substrates. The coating surface chemistry and morphology information is based upon XPS and AFM studies on pyrolytic graphite substrate. Two types of plasma surface modification techniques have been attempted: one is to make the surface more reactive for structural components and the other is to make the surface more inert for stand-alone structures. In order to achieve these goals plasma assisted oxide and fluorocarbon coatings are studied in detail. The synthesized oxide and fluorocarbon coating chemistries are comparable to conventional silica (SiO2) and polytetrafluoroethylene (PTFE, -CF2-). It is seen that the fluorocarbon coatings provide moisture resistance to graphitic foam by making the surface inert at the nanometer scale. On the other hand, plasma assisted oxide coating is a feasible and effective means of improving the wettability and dispersion of foam and nanofibers in organic polymer matrix material. Surface analysis as well as microstructural studies and mechanical tests have shown encouraging results. The interface reactions between graphite (coated and uncoated) and epoxy have also been studied in detail. Nano-scale plasma coatings have also been applied for metal matrix composites and semiconductor related applications. The fluorocarbon coating promote delamination/exfoliation of the metal on graphite, hence may be used for patterning or lithography. Oxide coatings seem to enhance the adhesion and metallic diffusion between graphite and metal, hence can be used for the development of metal matrix composites. Additionally, oxide coating seems to enhance the length and density of nanotubes synthesized on carbon structures, desired for the design of advanced nano-composites.

  4. Pulsed Plasma Thruster Plume Study: Symmetry and Impact on Spacecraft Surfaces

    NASA Technical Reports Server (NTRS)

    Arrington, Lynn A.; Marrese, Colleen M.; Blandino, John J.

    2000-01-01

    Twenty-four witness plates were positioned on perpendicular arrays near a breadboard Pulsed Plasma Thruster (PPT) to collect plume constituents for analysis. Over one million shots were fired during the experiment at 43 J using fluorocarbon polymer propellant. The asymmetry of the film deposition on the witness plates was investigated with mass and thickness measurements and correlated with off-axis thrust vector measurements. The composition of the films was determined. The transmittance and reflectance of the films were measured and the absorption coefficients were calculated in the wavelength range from 350 to 1200 mn. These data were applied to calculate the loss in signal intensity through the films, which will impact the visibility of spaceborne interferometer systems positioned by these thrusters.

  5. Burst behavior at a capillary tip: Effect of low and high surface tension.

    PubMed

    Agonafer, Damena D; Lopez, Ken; Palko, James W; Won, Yoonjin; Santiago, Juan G; Goodson, Kenneth E

    2015-10-01

    Liquid retention in micron and millimeter scale devices is important for maintaining stable interfaces in various processes including bimolecular separation, phase change heat transfer, and water desalination. There have been several studies of re-entrant geometries, and very few studies on retaining low surface tension liquids such as fluorocarbon-based dielectric liquids. Here, we study retention of a liquid with very low contact angles using borosilicate glass capillary tips. We analyzed capillary tips with outer diameters ranging from 250 to 840 ?m and measured Laplace pressures up to 2.9 kPa. Experimental results agree well with a numerical model that predicts burst pressure (the maximum Laplace pressure for liquid retention), which is a function of the outer diameter (D) and capillary exit edge radius of curvature (r). PMID:26046980

  6. Extraction studies. Final report, May 6, 1996--September 30, 1997

    SciTech Connect

    1997-10-09

    During the first week of this effort, an Alpkem RFA-300 4-channel automated chemical analyzer was transferred to the basement of building 42 at TA-46 for the purpose of performing extraction studies. Initially, this instrumentation was applied to soil samples known to contain DNA. Using the SFA (Segmented Flow Analysis) technique, several fluidic systems were evaluated to perform on-line filtration of several varieties of soil obtained from Cheryl Kuske and Kaysie Banton (TA-43, Bldg. 1). Progress reports were issued monthly beginning May 15, 1996. Early in 1997 there was a shift from the conventional 2-phase system (aqueous + air) to a 3-phase system (oil + aqueous + air) to drastically reduce sample size and reagent consumption. Computer animation was recorded on videotape for presentations. The time remaining on the subcontract was devoted to setting up existing equipment to incorporate the 3rd phase (a special fluorocarbon oil obtained from DuPont).

  7. Apparatus and method for atmospheric pressure reactive atom plasma processing for shaping of damage free surfaces

    DOEpatents

    Carr; Jeffrey W.

    2009-03-31

    Fabrication apparatus and methods are disclosed for shaping and finishing difficult materials with no subsurface damage. The apparatus and methods use an atmospheric pressure mixed gas plasma discharge as a sub-aperture polisher of, for example, fused silica and single crystal silicon, silicon carbide and other materials. In one example, workpiece material is removed at the atomic level through reaction with fluorine atoms. In this example, these reactive species are produced by a noble gas plasma from trace constituent fluorocarbons or other fluorine containing gases added to the host argon matrix. The products of the reaction are gas phase compounds that flow from the surface of the workpiece, exposing fresh material to the etchant without condensation and redeposition on the newly created surface. The discharge provides a stable and predictable distribution of reactive species permitting the generation of a predetermined surface by translating the plasma across the workpiece along a calculated path.

  8. Development of a special purpose spacecraft interior coating, phase 1

    NASA Technical Reports Server (NTRS)

    Bartoszek, E. J.; Nannelli, P.

    1975-01-01

    Coating formulations were developed consisting of latex blends of fluorocarbon polymers, acrylic resins, stabilizers, modifiers, other additives, and a variety of inorganic pigments. Suitable latex primers were also developed from an acrylic latex base. The formulations dried to touch in about one hour and were fully dry in about twenty-four hours under normal room temperature and humidity conditions. The resulting coatings displayed good optical and mechanical properties, including excellent bonding to (pre-treated) substrates. In addition, the preferred compositions were found to be self-extinguishing when applied to nonflammable substrates and could meet the offgassing requirements specified by NASA for the intended application. Improvements are needed in abrasion resistance and hardness.

  9. Plasma and ion fluorination for chemical hardening of synthetic rubbers. Final report, 30 September 1988-30 September 1989

    SciTech Connect

    Legg, K.O.

    1989-10-01

    The purpose of this Phase I SBIR program was to investigate ways of fluorinating the surfaces of rubber materials to reduce their susceptibility to wetting and permeation by chemical warfare agents. Nitrile, butyl, and neoprene rubbers were studied. Fluorination was accomplished by direct implantation of ions into the surface and by rf plasma fluorination with freon gases. The rubber materials were examined for contact angle of diethyl malonate (DEM) drops, critical surface tension, and DEM uptake, and were characterized microscopy and ESCA. Ion implantation led to embrittlement and cracking of the surfaces, causing more rapid wetting by DEM. Plasma fluorination tended to deposit a fluorocarbon film on the surface rather than to introduce fluorine into the material. Some of the fluorinated films exhibited greater DEM initial contact angles and slower absorption, although after three hours the absorption rate increased to that of the untreated rubbers. Hence, this treatment provided some temporary improvement, but it was insufficient for proper protection.

  10. Cell separations and the demixing of aqueous two phase polymer solutions in microgravity

    NASA Technical Reports Server (NTRS)

    Brooks, Donald E.; Bamberger, Stephan; Harris, J. M.; Van Alstine, James M.

    1991-01-01

    Partition in phase separated aqueous polymer solutions is a cell separation procedure thought to be adversely influenced by gravity. In preparation for performing cell partitioning experiments in space, and to provide general information concerning the demixing of immiscible liquids in low gravity, a series of phase separated aqueous polymer solutions have been flown on two shuttle flights. Fluorocarbon oil and water emulsions were also flown on the second flight. The aqueous polymer emulsions, which in one g demix largely by sedimentation and convection due to the density differences between the phases, demixed more slowly than on the ground and the final disposition of the phases was determined by the wetting of the container wall by the phases. The demixing behavior and kinetics were influenced by the phase volume ratio, physical properties of the systems and chamber wall interaction. The average domain size increased linearly with time as the systems demixed.

  11. A proximity focusing RICH detector for kaon physics at Jefferson lab hall A

    SciTech Connect

    F. Garibaldi; E. Cisbani; S. Colilli; F. Cusanno; S. Frullani; R. Fratoni; F. Giuliani; M. Gricia; M. Iodice; M. Lucentini; L. Pierangeli; F. Santavenere; G.M. Urciuoli; P. Veneroni; G. De Cataldo; R. De Leo; L. Lagamba; E. Nappi; V. Paticchio; J. LeRose; B. Kross; B. Reitz; J. Segal; C. Zorn; H. Breuer

    2003-04-01

    Important information on the LN interaction can be obtained from High Resolution Hypernuclear Spectroscopy experiments with electromagnetic probes. A challenging experiment on electroproduction of hypernuclei is scheduled for 2003 in Hall A at Jefferson Lab. One of the challenges is the high performance particle identification system needed. The signal is expected to be rare compared to the very high pion and proton backgrounds due to the small electron and kaon detection angles. The ''standard'' Hall A PID apparatus (TOF and two aerogel threshold Cherenkov detectors) does not provide sufficient suppression of the background. Simulations and calculations have shown that a RICH detector would solve the problem. A proximity focusing fluorocarbon/CsI detector similar to the ALICE RICH detector has been designed, built, tested and commissioned. The results show that the detector performs as expected.

  12. Ultrasonic decontamination in perfluorinated liquids of radioactive circuit boards

    SciTech Connect

    Yam, C.S.; Harling, O.K.; Kaiser, R.

    1994-12-31

    A laboratory-scale ultrasonic decontamination system has been developed to demonstrate the application of Entropic System`s enhanced particle removal process to the radioactive decontamination of electronic circuit boards. The process uses inert perfluorinated liquids as the working media; the liquids have zero ozone depletion potential, are nontoxic, non-flammable, and are generally recognized as nonhazardous materials. The parts to be cleaned are first sonicated with a dilute solution of a high-molecular-weight fluorocarbon surfactant in an inert perfluorinated liquid. The combination of ultrasonic agitation and liquid flow promotes the detachment of the particles from the surface of the part being cleaned, their transfer from the boundary layer into the bulk liquid, and their removal from the cleaning environment, thereby reducing the probability of particle redeposition. After the cleaning process, the parts are rinsed with the pure perfluorinated liquid to remove residual surfactant. The parts are recovered after the perfluorinated liquid is evaporated into air.

  13. Avoiding Steric Congestion in Dendrimer Growth through Proportionate Branching. A Twist on da Vinci's Rule of Tree Branching

    SciTech Connect

    Yue, Xuyi; Taraban, Marc B.; Hyland, Laura L.; Yu, Yihua Bruce

    2012-10-05

    In making defect-free macromolecules, the challenge occurs during chemical synthesis. This challenge is especially pronounced in dendrimer synthesis where exponential growth quickly leads to steric congestion. To overcome this difficulty, proportionate branching in dendrimer growth is proposed. In proportionate branching, both the number and the length of branches increase exponentially but in opposite directions to mimic tree growth. The effectiveness of this strategy is demonstrated through the synthesis of a fluorocarbon dendron containing 243 chemically identical fluorine atoms with a MW of 9082 Da. Monodispersity is confirmed by nuclear magnetic resonance spectroscopy, mass spectrometry, and small-angle X-ray scattering. Moreover, growing different parts proportionately, as nature does, could be a general strategy to achieve defect-free synthesis of macromolecules.

  14. FCKW als Tracer für die Ausbreitung von Altablagerungsemissionen im Grundwasser

    NASA Astrophysics Data System (ADS)

    Kühn, S.; Struppe, T.; Kerndorff, H.; Oster, H.

    2009-06-01

    Emissions from abandoned waste disposal sites into groundwater are difficult to trace further downstream because of their complexity. Typical tracers, for example, like chloride, boron and sulphate are likely to be influenced by several factors like saline waters, emissions from seepage pits and leaky sewers. These types of components are therefore not suitable to characterise groundwater contamination caused by abandoned waste disposal sites; they will thus not be further discussed in this paper. However, due to their special geochemical properties like negligible absorption and degradation rates, chlorinated fluorocarbons, especially difluoro-dichloromethane (F12), which are frequently emitted from abandoned waste disposal sites, are particularly suitable for the detection of maximum contaminant emissions to groundwater. These elements are crucial for the assessment of groundwater contamination and the employment of natural attenuation as a remediation measure.

  15. Electron ionization of open/closed chain isocarbonic molecules relevant in plasma processing: Theoretical cross sections

    SciTech Connect

    Patel, Umang R.; Joshipura, K. N.; Pandya, Siddharth H.; Kothari, Harshit N.

    2014-01-28

    In this paper, we report theoretical electron impact ionization cross sections from threshold to 2000 eV for isocarbonic open chain molecules C{sub 4}H{sub 6}, C{sub 4}H{sub 8}, C{sub 4}F{sub 6} including their isomers, and closed chain molecules c-C{sub 4}H{sub 8} and c-C{sub 4}F{sub 8}. Theoretical formalism employed presently, viz., Complex Scattering Potential-ionization contribution method has been used successfully for a variety of polyatomic molecules. The present ionization calculations are very important since results available for the studied targets are either scarce or none. Our work affords comparison of C{sub 4} containing hydrocarbon versus fluorocarbon molecules. Comparisons of the present ionization cross sections are made wherever possible, and new ionization data are also presented.

  16. Effects of tacky mat contamination on bond degradation for Chemlok/liner and NBR/liner bonds

    NASA Technical Reports Server (NTRS)

    Padilla, A. M.

    1989-01-01

    Tacky mats are placed by the rubber lay-up areas for the solid rocket motor segments. These mats dust off the shoes prior to entering the platform where the lay-up work is performed. The possibility exists that a tacky mat could be touched with gloved hands prior to handling the uncured nitride butadiene rubber (NBR). Tests were run to determine if NBR were accidentally touched would there be any degradation of the liner/NBR bond. The tacky mats were judged solely on the basis of bond degradation caused by either direct or indirect contamination. Test results all indicate that there was no notable NBR/Chemlok or liner/NBR bond degradation on samples that came into contact with the tacky mat material. Testing procedures are described. The tacky mat adhesive composition does not contain fluorocarbons or release agents that would affect bonding.

  17. Versatile Coating

    NASA Technical Reports Server (NTRS)

    1990-01-01

    A radome at Logan Airport and a large parabolic antenna at the Wang Building in Massachusetts are protected from weather, corrosion and ultraviolet radiation by a coating, specially designed for antennas and radomes, known as CRC Weathertite 6000. The CRC 6000 line that emerged from Boyd Coatings Research Co., Inc. is a solid dispersion of fluorocarbon polymer and polyurethane that yields a tough, durable film with superior ultraviolet resistance and the ability to repel water and ice over a long term. Additionally, it provides resistance to corrosion, abrasion, chemical attacks and impacts. Material can be used on a variety of substrates, such as fiberglass, wood, plastic and concrete in addition to steel and aluminum. In addition Boyd Coatings sees CRC 6000 applicability as an anti-icing system coated on the leading edge of aircraft wings.

  18. The effects of specified chemical meals on food intake.

    PubMed

    Koopmans, H S; Maggio, C A

    1978-10-01

    Rats received intragastric infusions of various specified chemical meals and were subsequently tested for a reduction in food intake. A second experiment, using a novel technique, tested for conditioned aversion to the meal infusions. The nonnutritive substances, kaolin clay and emulsified fluorocarbon, had no significant effect on food intake. Infusions of 1 M glucose and 1 M sorbitol reduced feeding behavior, but the 1 M sorbitol infusion also produced a conditioned aversion to flavored pellets paired with the sorbitol infusion, showing that the reduced feeding could have been caused by discomfort. Infusion of a high-fat meal consisting of emulsified triolein mixed with small amounts of sugar and protein or the rat's normal liquid diet, Nutrament, also reduced food intake, and both infusions failed to produce a conditioned aversion. The use of specified meals to understand the chemical basis of satiety requires a sensitive behavioral test to establish that the meal does not cause discomfort or other nonspecific effects. PMID:707387

  19. Development of inspection techniques for quantitatively measuring surface contamination on SRM hardware

    NASA Technical Reports Server (NTRS)

    Law, R. D.

    1989-01-01

    A contaminant is any material or substance which is potentially undesirable or which may adversely affect any part, component, or assembly. Contamination control of SRM hardware surfaces is a serious concern, for both Thiokol and NASA, with particular concern for contaminants which may adversely affect bonding surfaces. The purpose of this study is to develop laboratory analytical techniques which will make it possible to certify the cleanliness of any designated surface, with special focus on particulates (dust, dirt, lint, etc.), oils (hydrocarbons, silicones, plasticizers, etc.), and greases (HD-2, fluorocarbon grease, etc.). The hardware surfaces of concern will include D6AC steel, aluminum alloys, anodized aluminum alloys, glass/phenolic, carbon/phenolic, NBR/asbestos-silica, and EPDM rubber.

  20. An e.s.c.a. study of atomic oxygen interactions with phosphazene-coated polyimide films

    NASA Technical Reports Server (NTRS)

    Fewell, Larry L.; Finney, Lorie

    1991-01-01

    Metallic as well as most nonmetallic materials experience oxidation and mass loss via surface erosion in low earth orbit as shown in previous Space Shuttle flights. This study is an evaluation of select polyphosphazene polymers and their resistance to atomic oxygen attack. Electron spectroscopy for chemical analysis examinations of the surfaces of polyphosphazene coatings were monitored for microstructural changes induced during exposures to atomic oxygen. Sample exposures in oxygen plasmas and O(3P) beam were compared as to their effect on surface compositional changes in the polyphosphazene coating. High resolution line scans revealed rearrangements in the polymer backbone and scissioning reactions involving fluorocarbon units of long chain fluoroalkoxy pendant groups. Atom percents and peak areas of all species provided a detailed profile of the microstructural changes induced in phosphazene polymers as a result of exposures to atomic oxygen.

  1. Spacecraft dielectric material properties and spacecraft charging

    NASA Technical Reports Server (NTRS)

    Frederickson, A. R.; Wall, J. A.; Cotts, D. B.; Bouquet, F. L.

    1986-01-01

    The physics of spacecraft charging is reviewed, and criteria for selecting and testing semiinsulating polymers (SIPs) to avoid charging are discussed and illustrated. Chapters are devoted to the required properties of dielectric materials, the charging process, discharge-pulse phenomena, design for minimum pulse size, design to prevent pulses, conduction in polymers, evaluation of SIPs that might prevent spacecraft charging, and the general response of dielectrics to space radiation. SIPs characterized include polyimides, fluorocarbons, thermoplastic polyesters, poly(alkanes), vinyl polymers and acrylates, polymers containing phthalocyanine, polyacene quinones, coordination polymers containing metal ions, conjugated-backbone polymers, and 'metallic' conducting polymers. Tables summarizing the results of SIP radiation tests (such as those performed for the NASA Galileo Project) are included.

  2. Energy Efficient Commercial Refrigeration with Carbon Dioxide Refrigerant and Scroll Expanders

    SciTech Connect

    Dieckmann, John

    2013-04-04

    Current supermarket refrigeration systems are built around conventional fluorocarbon refrigerants – HFC-134a and the HFC blends R-507 and R404A, which replaced the CFC refrigerants, R-12 and R-502, respectively, used prior to the Montreal Protocol phase out of ozone depleting substances. While the HFC refrigerants are non-ozone depleting, they are strong greenhouse gases, so there has been continued interest in replacing them, particularly in applications with above average refrigerant leakage. Large supermarket refrigeration systems have proven to be particularly difficult to maintain in a leak-tight condition. Refrigerant charge losses of 15% of total charge per year are the norm, making the global warming impact of refrigerant emissions comparable to that associated with the energy consumption of these systems.

  3. Development and evaluation of elastomeric materials for geothermal applications

    NASA Technical Reports Server (NTRS)

    Mueller, W. A.; Kalfayan, S. H.; Reilly, W. W.; Ingham, J. D.

    1978-01-01

    A material for a casing packer for service for 24 hours in a geothermal environment was developed by synthesis of new elastomers and formulation of available materials. Formulation included use of commercial elastomer gumstocks and also crosslinking of plastic (high Tg) materials. Fibrous reinforcement of fluorocarbon rubbers was emphasized. Organic fiber reinforcement did not increase hot properties significantly. Glass fiber reinforcement gave significant increase in tensile properties. Elongation was reduced, and the glass-reinforced composition examined so far did not hold up well in the geothermal environment. Colloidal asbestos fibers were also investigated. A few experiments with polyphenyl ether gave material with low tensile and high compression set. Available high styrene SBR compositions were studied. Work to date suggests that new synthetic polymers will be required for service in geothermal environments.

  4. Cathodic electrocatalyst layer for electrochemical generation of hydrogen peroxide

    NASA Technical Reports Server (NTRS)

    Rhodes, Christopher P. (Inventor); Tennakoon, Charles L. K. (Inventor); Singh, Waheguru Pal (Inventor); Anderson, Kelvin C. (Inventor)

    2011-01-01

    A cathodic gas diffusion electrode for the electrochemical production of aqueous hydrogen peroxide solutions. The cathodic gas diffusion electrode comprises an electrically conductive gas diffusion substrate and a cathodic electrocatalyst layer supported on the gas diffusion substrate. A novel cathodic electrocatalyst layer comprises a cathodic electrocatalyst, a substantially water-insoluble quaternary ammonium compound, a fluorocarbon polymer hydrophobic agent and binder, and a perfluoronated sulphonic acid polymer. An electrochemical cell using the novel cathodic electrocatalyst layer has been shown to produce an aqueous solution having between 8 and 14 weight percent hydrogen peroxide. Furthermore, such electrochemical cells have shown stable production of hydrogen peroxide solutions over 1000 hours of operation including numerous system shutdowns.

  5. Tuned alexandrite laser for dentistry

    NASA Astrophysics Data System (ADS)

    Sulc, Jan; Jelinkova, Helena; Dostalova, Tatjana; Miyagi, Mitsunobu

    1999-12-01

    A tunable solid state laser system has been developed emitting visible light in the region from 710 to 775 nm, which can be used for medical applications. The laser head of this system is composed of alexandrite crystal rod, two dielectric mirrors, and a tuning element. The maximum reached output energy in the free running multimode regime was 400 mJ with the pulse duration of 70 micrometers . The output laser radiation was guided via a multimode quartz fiber or via a special fluorocarbon polymer-coated silver hollow glass waveguide. At first, this radiation with laser fluency of 2.5 J/cm2 was used for the ablation of dental calculus. Next, the laser radiation propagation in the root canal and its effect on bacteria was proved. The dissipated energy measurement was made inside and outside the tooth. Hence, the alexandrite laser could be useful for medical applications in dentistry.

  6. Total reflection X-ray photoelectron spectroscopy as a semiconductor lubricant elemental analysis method

    NASA Astrophysics Data System (ADS)

    Alshehabi, Abbas; Sasaki, Nobuharu; Kawai, Jun

    2015-12-01

    Photoelectron spectra from a typical hard disk storage media device (HDD) were measured at total reflection and non-total reflection at unburnished, acetone-cleaned, and argon-sputtered conditions. F, O, N, and C usually making the upper layer of a typical hard disk medium were detected. Enhancement of the photoelectron emission of the fluorocarbon lubricant was observed at total reflection. Pt and Co were only found by non-total X-ray photoelectron spectroscopy (XPS) because they are constituents of a deeper region than the top and interface regions. Argon-sputtered, ultrasonic acetone-cleaned, and unburnished top layers were compared at total and non-total reflection conditions. Total reflection X-ray photoelectron spectroscopy (TRXPS) is demonstrated to be a powerful tool for storage media lubrication layer chemical state analysis, reliable for industrial quality control application , and reproducible.

  7. Aviation gas turbine lubricants - military and civil aspects: aviation fuel and lubricants - performance testing; Proceedings of the Aerospace Technology Conference and Exposition, Long Beach, CA, October 14-17, 1985

    SciTech Connect

    Not Available

    1985-01-01

    Research and development programs in the areas of gas turbine lubricants for civil and military aviation and the performance testing of aviation gas turbine fuels and lubricants are discussed. The topics addressed include: laboratory and field evaluation of a high temperature jet engine oil, performance advantages of high load aviation lubricants, fluorocarbon elastomer compatibility with gas turbine lubricants, potential benefits in the development of a dedicated helicopter transmission lubricant, and feasibility of formulating advanced four centistoke gas turbine oils. Also covered are: advanced lubricants for aircraft turbine engines, future trends for U.S. Naval aviation propulsion system lubricants, electrochemical evaluation of corrosivity in turbine engine oils, the influence of esters on elastomer seals, deposition in gas turbine oil systems, development of the portable water separometer for the WSIM test, influence of JFTOT operating parameters on the assessment of fuel thermal stability, and evaluation of JFTOT tube deposits by carbon burnoff.

  8. Surface characteristics of etched parylene-C films for low-damaged patterning process using inductively-coupled O2/CHF3 gas plasma

    NASA Astrophysics Data System (ADS)

    Ham, Yong-Hyun; Shutov, Dmitriy Alexandrovich; Kwon, Kwang-Ho

    2013-05-01

    We investigated the effectiveness of CHF3 admixture in O2 plasma for a low damage patterning process. We used inductively-coupled plasma (ICP) etching of parylene-C thin films with O2/CHF3 gas mixtures. Plasma diagnostics were performed by using a double Langmuir probe. Also in order to examine the relationship between the plasma and surface energy, we attempted to conduct a simplified model-based analysis of the CHF3/O2 plasma. The surface energy decreased as the admixture fraction increased with fluorocarbon containing gas. The decreased surface energy is related to the functional groups of CFx polymer at binding energy of around 290 eV and low ion physical damage. We observed that a small addition of CHF3 to O2 plasma produced a high etch rate, low surface energy, and low roughness compared to pure oxygen plasma.

  9. The Effect of Supercritical Fluids on Solid Acid Catalyst Alkylation

    SciTech Connect

    Ginosar, Daniel Michael; Thompson, David Neil; Burch, Kyle Coates; Zalewski, D. J.

    2002-05-01

    The alkylation of isobutane with trans-2-butene was explored over six solid acid catalysts in the liquid, near-critical liquid, and supercritical regions through the addition of an inert cosolvent to the reaction feed mixture. The addition of supercritical cosolvents did not result in sustained catalytic alkylation activity. A modest improvement in product yield was obtained with the addition of methane in the modified-liquid region; however, catalyst longevity and product selectivity were decreased compared to cosolvent-free liquid conditions. This paper describes the catalyst screening and selection process, an exploration of catalyst performance with varying concentrations of methane, and an examination of the effects of seven supercritical fluids on catalyst performance. The catalysts included two zeolites, two sulfated metal oxides, and two Nafion catalysts. Three hydrocarbons, two fluorocarbons, carbon dioxide, and sulfur hexafluoride were explored as inert cosolvents added to the reaction mixture.

  10. Development of a high-efficiency, gas-fired, heat pipe, warm-air heating system

    NASA Astrophysics Data System (ADS)

    Feldman, S.; Becker, F.

    1985-01-01

    With the introduction by Borg-Warner of the Heatpipe Furnace, one of the major goals of this program was achieved. This milestone was reached after a 105,000 Btu/hr, 85 percent efficient manufacturing prototype heat pipe furnace was designed, fabricated, and tested by Thermo Electron. Other prototype units of different capacities were also designed. The prototypes underwent extensive field testing and in-house accelerated life-cycle testing, indicating that they were reliable, safe, and cost-competitive. Specific issues like freeze protection and oil contamination were addressed. Two different prototype ultrahigh-efficiency condensing furnaces were designed, fabricated and tested. One approach utilized a fluorocarbon-filled heat pipe as a secondary-stage heat exchanger; the other used a plate finned tube coil as the heat exchanger.

  11. Development of a high-efficiency, gas-fired, heat-pipe, warm-air heating system. Final report, January 1983-December 1984

    SciTech Connect

    Feldman, S.; Becker, F.

    1985-01-01

    With the introduction by Borg-Warner of the Heatpipe Furnace, one of the major goals of this program was achieved. This milestone was reached after a 105,000 Btu/hr, 85% efficient manufacturing prototype heat-pipe furnace was designed, fabricated, and tested by Thermo Electron. Other prototype units of different capacities were also designed. The prototypes underwent extensive field testing and in-house accelerated life-cycle testing, indicating that they were reliable, safe, and cost-competitive. Specific issues like freeze protection and oil contamination were addressed. Two different prototype ultrahigh-efficiency condensing furnaces were designed, fabricated, and tested. One approach utilized a fluorocarbon-filled heat pipe as a secondary-stage heat exchanger; the other used a plate finned-tube coil as the heat exchanger.

  12. Network flow model analysis of the impact of chlorofluorocarbon phaseout on acid-grade fluorspar. Information circular/1994

    SciTech Connect

    Slatnick, J.A.; Fulton, R.B.

    1994-12-31

    Chlorofluorocarbons (CFC`s) are being phased out and eventually banned under extensive international agreements because the chlorine in CFC`s is thought to deplete the Earth`s ozone layer. As a result, the fluorspar mining industry, which is the source of fluorine in fluorocarbons through intermediate hydrofluoric acid, is being affected. Concern for this impact has led the U.S. Bureau of Mines to employ its capabilities to analyze various scenarios in the evolution of CFC replacements and substitutes to determine their effect on fluorspar mining. This report utilizes a network flow model to examine the effects of proposed replacements for CFC`s, in terms of fluorine content, on fluorspar operations worldwide and on hydrofluoric acid plants in North America and Europe.

  13. New chemical alternative for ozone-depleting substances: HFC-245ca. Final report, August 1987-June 1996

    SciTech Connect

    Smith, N.D.; Gage, C.L.; Baskin, E.; Hendriks, R.V.

    1996-12-01

    The report gives results of a preliminary evaluation of a new hydrofluoro-carbon (HF)--HFC-245ca or 1,1,2,2,3-pentafluoropropane as a possible alternative for chlorofluorocarbon (CFC)-11 (trichlorofluoromethane) and hydrochloro-fluorocarbon (HCFC)-123 (1,1,1-trifluoro- 2,2-dichloroethane) refrigerant for low-pressure chillers and as a possible alternative for CFC-111 and HCFC-14lb (1-fluoro-1,1-dichloroethane) blowing agents for polyisocyanurate/polyurethane insulation forms. Evaluation tests included an examination of its flammability, stability, thermophysical properties, lubricant miscibility and lubricity, materials compatibility, acute inhalation toxicity, and refrigeration performance.An azeotrope composed of HFC-245ca and HFC-338mccq (1,1,1,2,3,4,4,4-octafluorobutane) was also examined from the standpointof reducing the flammability of HFC-245ca.

  14. Plasma Reactor Modeling and Validation Experiments

    NASA Technical Reports Server (NTRS)

    Meyyappan, M.; Bose, D.; Hash, D.; Hwang, H.; Cruden, B.; Sharma, S. P.; Rao, M. V. V. S.; Arnold, Jim (Technical Monitor)

    2001-01-01

    Plasma processing is a key processing stop in integrated circuit manufacturing. Low pressure, high density plum reactors are widely used for etching and deposition. Inductively coupled plasma (ICP) source has become popular recently in many processing applications. In order to accelerate equipment and process design, an understanding of the physics and chemistry, particularly, plasma power coupling, plasma and processing uniformity and mechanism is important. This understanding is facilitated by comprehensive modeling and simulation as well as plasma diagnostics to provide the necessary data for model validation which are addressed in this presentation. We have developed a complete code for simulating an ICP reactor and the model consists of transport of electrons, ions, and neutrals, Poisson's equation, and Maxwell's equation along with gas flow and energy equations. Results will be presented for chlorine and fluorocarbon plasmas and compared with data from Langmuir probe, mass spectrometry and FTIR.

  15. Neutron Radiography of Fluid Flow for Geothermal Energy Research

    NASA Astrophysics Data System (ADS)

    Bingham, P.; Polsky, Y.; Anovitz, L.; Carmichael, J.; Bilheux, H.; Jacobsen, D.; Hussey, D.

    Enhanced geothermal systems seek to expand the potential for geothermal energy by engineering heat exchange systems within the earth. A neutron radiography imaging method has been developed for the study of fluid flow through rock under environmental conditions found in enhanced geothermal energy systems. For this method, a pressure vessel suitable for neutron radiography was designed and fabricated, modifications to imaging instrument setups were tested, multiple contrast agents were tested, and algorithms developed for tracking of flow. The method has shown success for tracking of single phase flow through a manufactured crack in a 3.81 cm (1.5 inch) diameter core within a pressure vessel capable of confinement up to 69 MPa (10,000 psi) using a particle tracking approach with bubbles of fluorocarbon-based fluid as the "particles" and imaging with 10 ms exposures.

  16. Chlorofluoromethanes in the stratosphere and some possible consequences for ozone

    NASA Technical Reports Server (NTRS)

    Turco, R. P.; Whitten, R. C.

    1975-01-01

    Inert chlorofluoromethanes are used by man as refrigerants and aerosol propellants. These substances eventually escape and diffuse upward into the stratosphere. At great enough heights, UV sunlight can photodissociate these chlorofluorocarbons into chlorine atoms which will catalytically destroy ozone molecules. Chlorofluoromethane production has been increasing steadily in recent years to its present level of about a megaton per year, and chlorofluorocarbon usage will probably continue to grow in the future. Calculations with a one-dimensional time-dependent atmospheric model suggests that, if projected increases in chlorofluoromethane use materialize and there is no tropospheric destruction mechanism for these gases, the total global abundance of ozone may be reduced by more than 20 per cent over the next 50 years. If the residence times for these fluorocarbons in the troposphere are in the range of 10-30 years, however, predicted ozone depletions would be significantly smaller.

  17. Ultrasmooth plasma polymerized coatings for laser-fusion targets

    SciTech Connect

    Letts, S.A.; Myers, D.W.; Witt, L.A.

    1980-08-26

    Coatings for laser fusion targets were deposited up to 135 ..mu..m thick by plasma polymerization onto 140 ..mu..m diameter DT filled glass microspheres. Ultrasmooth surfaces (no defect higher than 0.1 ..mu..m) were achieved by eliminating particulate contamination. Process generated particles were eliminated by determining the optimum operating conditions of power, gas flow, and pressure, and maintaining these conditions through feedback control. From a study of coating defects grown over known surface irregularities, a quantitative relationship between irregularity size, film thickness, and defect size was determined. This relationship was used to set standards for the maximum microshell surface irregularity tolerable in the production of hydrocarbon or fluorocarbon coated laser fusion targets.

  18. Ionic cleaning after wave solder and before conformal coat

    NASA Astrophysics Data System (ADS)

    Nguygen, Tochau N.; Sutherland, Thomas H.

    An account is given of efforts made by a military electronics manufacturer to upgrade product reliability in response to the printed writing board (PWB) ionic cleanliness requirements recently set out in MIL-P-28809 Rev. A. These requirements had to be met both after wave soldering, involving the immediate removal of ionically active RA flux, and immediately before conformal coating, in order to remove the less active RMA flux and bonding contaminants. Attention is given to the results of a test program which compared the effectiveness with which five different solvents and two (batch and conveyorized vapor degreasing) cleaning methods cleaned representative PWBs containing many components. Alcohol-containing fluorocarbon blends were adequate, but the most densely packed PWBs required a supplemental water rinse.

  19. The 1977 intertropical convergence zone experiment

    NASA Technical Reports Server (NTRS)

    Poppoff, I. G. (Editor); Page, W. A. (Editor); Margozzi, A. P. (Editor)

    1979-01-01

    Data are presented from the 1977 Intertropical Convergence Zone (ITCZ) Experiment conducted in the Panama Canal Zone in July 1977. Measurements were made daily over a 16-day period when the ITCZ moved across the Canal Zone. Two aircraft (Learjet and U-2) flew daily and provided data from horizontal traverses at several altitudes to 21.3 km of ozone, temperature, pressure, water vapor, aerosols, fluorocarbons, methane, nitrous oxide, nitric oxide, and nitric acid. Balloonsondes flown four times per day provided data on ozone, wind fields, pressure, temperature, and humidities to altitudes near 30 km. Rocketsondes provided daily data to altitudes near 69 km. Satellite photography provided detailed cloud information. Descriptions of individual experiments and detailed compilations of all results are provided.

  20. Hollow Bragg waveguides fabricated by controlled buckling of Si/SiO2 multilayers.

    PubMed

    Epp, E; Ponnampalam, N; Newman, W; Drobot, B; McMullin, J N; Meldrum, A F; DeCorby, R G

    2010-11-22

    We describe integrated air-core waveguides with Bragg reflector claddings, fabricated by controlled delamination and buckling of sputtered Si/SiO2 multilayers. Thin film deposition parameters were tailored to produce a desired amount of compressive stress, and a patterned, embedded fluorocarbon layer was used to define regions of reduced adhesion. Self-assembled air channels formed either spontaneously or upon heating-induced decomposition of the patterned film. Preliminary optical experiments confirmed that light is confined to the air channels by a photonic band-gap guidance mechanism, with loss ~5 dB/cm in the 1550 nm wavelength region. The waveguides employ standard silicon processes and have potential applications in MEMS and lab-on-chip systems. PMID:21164836

  1. The use of atmospheric measurements to constrain model predictions of ozone change from chlorine perturbations

    NASA Technical Reports Server (NTRS)

    Douglass, Anne R.; Stolarski, Richard S.

    1987-01-01

    Atmospheric photochemistry models have been used to predict the sensitivity of the ozone layer to various perturbations. These same models also predict concentrations of chemical species in the present day atmosphere which can be compared to observations. Model results for both present day values and sensitivity to perturbation depend upon input data for reaction rates, photodissociation rates, and boundary conditions. A method of combining the results of a Monte Carlo uncertainty analysis with the existing set of present atmospheric species measurements is developed. The method is used to examine the range of values for the sensitivity of ozone to chlorine perturbations that is possible within the currently accepted ranges for input data. It is found that model runs which predict ozone column losses much greater than 10 percent as a result of present fluorocarbon fluxes produce concentrations and column amounts in the present atmosphere which are inconsistent with the measurements for ClO, HCl, NO, NO2, and HNO3.

  2. Dynamics and Spreading of pentanol and other alcohols for MEMS applications

    NASA Astrophysics Data System (ADS)

    Miller, Brendan; Hook, David; Krim, Jacqueline

    2009-03-01

    Microelectromechanical Systems (MEMS) have the potential to revolutionize widespread technologies, but tribological issues are currently preventing commercialization of some devices. Self-assembled monolayers (SAMs), while highly effective against release related stiction, are ineffective as MEMS lubricants [1]. Vapor phase lubrication has been proposed as a solution to the issue of tribological failure in MEMS with alcohol vapors attracting much interest. In an effort to understand the basic mechanisms of lubrication we have performed a quartz crystal microbalance (QCM) study of the uptake, sliding friction, and spreading rates of adsorbed alcohols on silicon and SAM treated substrates. [1] D. A. Hook, S. J. Timpe, M. T. Dugger, and J. Krim. Tribological degradation of fluorocarbon coated silicon microdevice surfaces in normal and sliding contact. J. Applied Physics 104 (2008).

  3. Foam films as thin liquid gas separation membranes.

    PubMed

    Ramanathan, Muruganathan; Müller, Hans Joachim; Möhwald, Helmuth; Krastev, Rumen

    2011-03-01

    In this letter, we testify the feasibility of using freestanding foam films as a thin liquid gas separation membrane. Diminishing bubble method was used as a tool to measure the permeability of pure gases like argon, nitrogen, and oxygen in addition to atmospheric air. All components of the foam film including the nature of the tail (fluorocarbon vs hydrocarbon), charge on the headgroup (anionic, cationic, and nonionic) and the thickness of the water core (Newton black film vs Common black film) were systematically varied to understand the permeation phenomena of pure gases. Overall results indicate that the permeability values for different gases are in accordance with magnitude of their molecular diameter. A smaller gaseous molecule permeates faster than the larger ones, indicating a new realm of application for foam films as size selective separation membranes. PMID:21314136

  4. Wide Angle, Single Screen, Gridded Square-Loop Frequency Selective Surface for Diplexing Two Closely Separated Frequency Bands

    NASA Technical Reports Server (NTRS)

    Wu, Te-Kao (Inventor)

    1996-01-01

    The design and performance of a wide angle, single screen, frequency selective surface (FSS) with gridded square-loop path elements are described for diplexing closely separated signal bands, for example, X- and Ku-band signals in an Orbiting Very Long Baseline Interferometer (OVLBI) earth station reflector antenna system, as well as other applications such as military and commercial communications via satellites. Excellent agreement is obtained between the predicted and measured results of this FSS design using the gridded square-loop patch elements sandwiched between 0.0889 cm thick tetrafluoroethylene fluorocarbon polymer (PTFE) slabs. Resonant frequency drift is reduced by 1 GHz with an incidence angle from 0 deg normal to 40 deg from normal.

  5. Implications of the Montreal Protocol for atmospheric emissions of alternative chemicals. Report for January-March 1988

    SciTech Connect

    Hummel, K.E.; Smith, N.D.; Harmon, D.L.

    1988-08-01

    This paper is about alternative chemicals. The substitution, of less ozone-depleting chemicals wherever it is cost effective and technically feasible, is expected because of anticipated future limitations on production and consumption of the fully halogenated chlorofluorocarbons (CFCs) and halons (fluorocarbons containing bromine atoms) covered by the Montreal Protocol. Certain alternative chemicals (e.g., HCFC-22 and methyl chloroform) are already used in applications other than as CFC substitutes. Projected future consumption of alternative chemicals includes such non-substitution use. Study results indicate that the 50% reduction in weighted CFC/halon consumption (weighted for ozone-depletion potential) required by the Protocol in 1998 could initially be achieved by alternative chemicals alone. However, alternative processes or products not requiring either the controlled substances or their substitute chemicals and/or substantial recovery and reuse of the chemicals would be needed to maintain the 50% level of reduction in the longer term.

  6. Coolant controversy heats up

    SciTech Connect

    Shanley, A.

    1997-11-01

    In 1987, nations of the world banded together under the Montreal Protocol to help protect the earth`s ozone layer. Now, ten years and $2.4 billion in new fluorocarbon R and D later, the ozone hole is still with us, as a black market in illegal chlorofluorocarbons thrives and legal trade in recycled CFCs continues. Unfortunately, each alternative to CFCs poses tradeoffs. Some hydrochlorofluorocarbons present lubricant compatibility problems, and, because they are also somewhat ozone depleting, they`ll be phased out in the US between 2010 and 2030, and earlier in Europe. Chlorine-free hydrofluorocarbons contribute to global warming and some require lubricant changes and retooling, while the processes that make them emit halogenated organics. This paper discusses compatibility, flammability, global warming, and supply problems.

  7. Tetraperchlorate of methane

    NASA Technical Reports Server (NTRS)

    Schack, C. J.

    1972-01-01

    The preparation of the tetraperchlorate of methane (TPM) was attempted. Displacement of halogen from carbon tetrahalides was accomplished with either CCl4 or CBr4 using the halogen perchlorates, ClOClO3, and BOClO3. Although the displacement process was successful, the generated carbon perchlorate intermediates were not isolated. Instead, these species decomposed to COCl2, CO2, and Cl2O7. The vigorous displacement reaction that often occurred required moderation. Fluorocarbon solvents and chlorine perchlorate were successfully tested for compatibility, permitting their use in these synthetic reactions. While the sought for moderating effect was obtained, the net result of the displacement of halogen from CX sub 4 substrates was the same as before. Thus only CO2, COCl2, and Cl2O7 were isolated.

  8. Role of Acentric Displacements on the Crystal Structure and Second-Harmonic Generating Properties of RbPbCO3F and CsPbCO3F

    PubMed Central

    2015-01-01

    Two lead fluorocarbonates, RbPbCO3F and CsPbCO3F, were synthesized and characterized. The materials were synthesized through solvothermal and conventional solid-state techniques. RbPbCO3F and CsPbCO3F were structurally characterized by single-crystal X-ray diffraction and exhibit three-dimensional (3D) crystal structures consisting of corner-shared PbO6F2 polyhedra. For RbPbCO3F, infrared and ultraviolet–visible spectroscopy and thermogravimetric and differential thermal analysis measurements were performed. RbPbCO3F is a new noncentrosymmetric material and crystallizes in the achiral and nonpolar space group P6̅m2 (crystal class 6̅m2). Powder second-harmonic generation (SHG) measurements on RbPbCO3F and CsPbCO3F using 1064 nm radiation revealed an SHG efficiency of approximately 250 and 300 × α-SiO2, respectively. Charge constants d33 of approximately 72 and 94 pm/V were obtained for RbPbCO3F and CsPbCO3F, respectively, through converse piezoelectric measurements. Electronic structure calculations indicate that the nonlinear optical response originates from the distorted PbO6F2 polyhedra, because of the even–odd parity mixing of the O 2p states with the nearly spherically symmetric 6s electrons of Pb2+. The degree of inversion symmetry breaking is quantified using a mode-polarization vector analysis and is correlated with cation size mismatch, from which it is possible to deduce the acentric properties of 3D alkali-metal fluorocarbonates. PMID:24867361

  9. Role of acentric displacements on the crystal structure and second-harmonic generating properties of RbPbCO3F and CsPbCO3F.

    PubMed

    Tran, T Thao; Halasyamani, P Shiv; Rondinelli, James M

    2014-06-16

    Two lead fluorocarbonates, RbPbCO3F and CsPbCO3F, were synthesized and characterized. The materials were synthesized through solvothermal and conventional solid-state techniques. RbPbCO3F and CsPbCO3F were structurally characterized by single-crystal X-ray diffraction and exhibit three-dimensional (3D) crystal structures consisting of corner-shared PbO6F2 polyhedra. For RbPbCO3F, infrared and ultraviolet-visible spectroscopy and thermogravimetric and differential thermal analysis measurements were performed. RbPbCO3F is a new noncentrosymmetric material and crystallizes in the achiral and nonpolar space group P6m2 (crystal class 6m2). Powder second-harmonic generation (SHG) measurements on RbPbCO3F and CsPbCO3F using 1064 nm radiation revealed an SHG efficiency of approximately 250 and 300 × α-SiO2, respectively. Charge constants d33 of approximately 72 and 94 pm/V were obtained for RbPbCO3F and CsPbCO3F, respectively, through converse piezoelectric measurements. Electronic structure calculations indicate that the nonlinear optical response originates from the distorted PbO6F2 polyhedra, because of the even-odd parity mixing of the O 2p states with the nearly spherically symmetric 6s electrons of Pb(2+). The degree of inversion symmetry breaking is quantified using a mode-polarization vector analysis and is correlated with cation size mismatch, from which it is possible to deduce the acentric properties of 3D alkali-metal fluorocarbonates. PMID:24867361

  10. Multi-technique Characterization of Adsorbed Peptide and Protein Orientation: LK310 and Protein G B1

    SciTech Connect

    Baio, J.; Weidner, T; Samuel, N; McCrea, K; Baugh, L; Stayton, P; Castner, D

    2010-01-01

    The ability to orient biologically active proteins on surfaces is a major challenge in the design, construction, and successful deployment of many medical technologies. As methods to orient biomolecules are developed, it is also essential to develop techniques that can accurately determine the orientation and structure of these materials. In this study, two model protein and peptide systems are presented to highlight the strengths of three surface analysis techniques for characterizing protein films: time-of-flight secondary-ion mass spectrometry (ToF-SIMS), sum-frequency generation (SFG) vibrational spectroscopy, and near-edge x-ray absorption fine structure (NEXAFS) spectroscopy. First, the orientation of Protein G B1, a rigid 6 kDa domain covalently attached to a maleimide-functionalized self-assembled monolayer, was examined using ToF-SIMS. Although the thickness of the Protein G layer was similar to the ToF-SIMS sampling depth, orientation of Protein G was successfully determined by analyzing the C{sub 2}H{sub 5}S{sup +} intensity, a secondary-ion derived from a methionine residue located at one end of the protein. Next, the secondary structure of a 13-mer leucine-lysine peptide (LK{sub 310}) adsorbed onto hydrophilic quartz and hydrophobic fluorocarbon surfaces was examined. SFG spectra indicated that the peptide's lysine side chains were ordered on the quartz surface, while the peptide's leucine side chains were ordered on the fluorocarbon surface. NEXAFS results provided complementary information about the structure of the LK{sub 310} film and the orientations of amide bonds within the LK{sub 310} peptide.

  11. Patterns of trace gases near sources of global pollution

    SciTech Connect

    Khalil, M.A.K.; Rasmussen, R.A. )

    1990-08-01

    Many trace gases are increasing in the earth's armosphere and may couase global environmental changes in the future. Consequently there has been growing interest in the cycles of the long-lived gases that are likely to contribute the most to global change. At present there are four such gases: methane (CH{sub 4}), nitrous oxide (N{sub 2}0), trichlorofluoromethane (CCl{sub 3}F,F-11), and dichlorodifluoromethane (CCl{sub 2}F{sub 2},F-12). Methane and N{sub 2}O are involved mostly in adding to the greenhouse effect with some role in the stratospheric ozone cycle, and the two main fluorocarbons (F-11 and F-12) are involved in the depletion of the ozone layer with some role in global warming. This paper is about the patterns of these trace gases near regions of global scale pollution. Our purpose is to provide a synthesis of observations from diverse environments and ecosystems of the world and to provide readers with intuitive connections between sources and concentrations. We will consider four types of regions: rice fields in CHina that are a major source of methane, urban areas of the United States and China that are sources of fluorocarbons and other gases, rivers and surrounding wetlands, specifically the Yangtze in China and the Amazon in Brazil, and finally the environment of Boola Boola National Forest in Australia populated by many speices of termites that are a source of methane to the atmosphere. Eventually these patterns can be translated into estimeates of fluxes from the various sources of global pollution.

  12. Damage by radicals and photons during plasma cleaning of porous low-k SiOCH. I. Ar/O{sub 2} and He/H{sub 2} plasmas

    SciTech Connect

    Shoeb, Juline; Wang Mingmei; Kushner, Mark J.

    2012-07-15

    Porous dielectric materials offer lower capacitances that reduce RC time delays in integrated circuits. Typical porous low dielectric (low-k) materials include SiOCH-silicon dioxide with carbon groups, principally -CH{sub 3}, lining the pores. Fluorocarbon plasmas are often used to etch such low-k materials. These processes leave a fluorocarbon polymer on the SiOCH surface that must be removed, often with oxygen or hydrogen containing plasmas. Pores open to the surface and that are internally connected provide pathways for reactive species to enter into the porous network and produce damage. For example, during cleaning using O{sub 2} containing plasmas, reactions of O atoms with -CH{sub 3} groups can increase the k-value by removing C atoms. Vacuum ultraviolet (VUV) photons produced by the plasma and that penetrate into the material can scission -Si-CH{sub 3} bonds and accelerate the removal of -CH{sub 3} groups. This paper reports on results from a computational investigation of Ar/O{sub 2} and He/H{sub 2} plasma cleaning of porous SiOCH when including the effects of VUV photons. The authors found that He/H{sub 2} plasmas are able to clean CF{sub x} polymers deposited during etching while producing milder damage to underlying -CH{sub 3} sites compared to O{sub 2} plasmas due to the lower reactivity of H atoms and the shorter penetration distance of photons produced in He/H{sub 2} plasmas.

  13. Solvent organization around the perfluoro group of coumarin 153 governs its photophysical properties: An experimental and simulation study of coumarin dyes in ethanol as well as fluorinated ethanol solvents.

    PubMed

    Mondal, Saptarsi; Halder, Ritaban; Biswas, Biswajit; Jana, Biman; Singh, Prashant Chandra

    2016-05-14

    The self-aggregation property of the perfluoro group containing molecules makes it important in the research fields of biology and polymer and organic synthesis. In the quest of understanding the role of the perfluoro group on the photophysical properties of perfluoro-containing molecules in biologically important fluoroethanol solvents, we have applied photophysical as well as molecular dynamics simulation techniques to explore the properties of perfluoro groups containing molecule coumarin-153 (C153) in ethanol (ETH), monofluoroethanol (MFE), difluoroethanol (DFE), and trifluoroethanol (TFE) and compared them with the molecules without perfluoro moiety, namely coumarin-6H (C6H) and coumarin-480 (C480). In contrast to C6H and C480, the excited state lifetime of C153 in fluorinated ETHs is not monotonic. The excited state lifetime of C153 decreases in MFE and DFE as compared to ETH, whereas in TFE, it increases as compared to MFE and DFE. Molecular dynamics simulation reveals that the carbon terminal away from the OH group of fluorinated ETHs has a preferential orientation near the perfluoro (CF3) group of C153. In MFE and DFE, the CF3 group of C153 prefers to have a CF2-F⋯H -(CHF) type of electrostatic interaction over CF2-F⋯F -(CH2) kind of dispersion interaction which increases the rate of nonradiative decay, probably due to the electrostatic nature of the CF2-F⋯H -(CHF) hydrogen bond. On the other hand, in TFE, C-F⋯ F-C type of dispersion interaction, also known as fluorous interaction, takes place between the CF3 groups of C153 and TFE which decreases the rate of nonradiative rate as compared to MFE and DFE, leading to the increased lifetime of C153 in TFE. Photophysical and MD simulation studies clearly depict that the structural organization of solvents and their interaction with the fluorocarbon group are crucial factors for the photophysical behavior of the fluorocarbon containing molecules. PMID:27179492

  14. Chemical dry cleaning and pretreatment on the electrical and reliability characteristic of high-k gate dielectrics in MOS device

    NASA Astrophysics Data System (ADS)

    Cheng, Chin-Lung; Wang, Tien-Ko; Chang-Liao, Kuei-Shu

    2003-07-01

    Effect of chemical dry cleaning (CDC) and pre-treatment (NH3 annealing) on the interface property of high-K gate dielectrics (NiTiO3) in MOS device have been investigated. A surface layer is damaged due to oxide dry etching (CHF3/CF4/Ar) process in active region formation. This damaged layer was generally removed by wet etching (HF) however it creates a rough layer on the substrate surface. It appears that the surface roughness by plasma dry etching is better then that by HF wet oxide etching. When the metal is directly deposited on the silicon substrate, a poor interface quality leads to a high leakage current. A damage-free, smooth surface, and thin interfacial layer formed on substrate surface are important for high-k gate dielectric process. Therefore, a method using Chemical Dry Cleaning (CF4/O2) is adopted after dry oxide etching (CHF3/CF4/Ar). In addition, CDC can then be adopted to effectively remove fluorocarbon residue and Si-F and Si-C bonds on the silicon surface etched in fluorocarbon plasma chemistry. After CDC, pre-deposition treatment can be employed to inhibit the growth of the interfacial layer. The pre-treatment strategies (NH3 annealing) are used to prevent silicide formation and to elevate the interface property of the devices. Finally, post deposition annealing (N2 annealing) can be performed to reduce the leakage current. These approaches not only strengthen the structure of Si-N bonds, but also improve the smoothness and uniformity at the interface of the metal oxide/silicon substrate.

  15. TEWI Analysis: Its Utility, Its Shortcomings, and Its Results

    SciTech Connect

    Baxter, V.D.; Fischer, S.K.; Sand, J.R.

    1999-09-13

    The past decade has been a challenging time for the refrigeration and air conditioning industry worldwide. Provisions of the Montreal Protocol and its amendments require the phaseout of chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) compounds that have been used extensively as insulating foam blowing agents and refrigerants in refrigeration systems, heat pumps, and air conditioners. In response, hydrofluorocarbon (HFC) compounds were proposed, developed, and are starting to be used as the primary alternatives to CFCs and HCFCs. However, in 1997 under the Kyoto Protocol, industrialized nations have agreed to roll back emissions of HCFCs, carbon dioxide (CO*), and four other greenhouse gases which threaten to cause excessive global warming. The US. Department of Energy and the Alternative Fluorocarbon Environmental Acceptability Study (AFEAS) jointly sponsored research projects to identify the major applications of CFCs, HCFCs, and HFCs and to examine the impacts of these compounds and the energy use of applications employing these compounds on global warming. The five major uses of fluorocarbons based on sales were automobile air conditioning, supermarket refrigeration, unitary heat pumps and air conditioning, chillers for cooling large office buildings, and household refrigeration. Almost all of the refrigerants used in these applications are global warming gases, and if the refrigerant leaks out of the system during operation, is lost during maintenance or is not recovered when the system is scraped, it contributes to global warming. But, it is also true that the energy consumed by refrigeration and air conditioning systems, in the form of electricity or the direct combustion of fossil fuel, results in the release of CO*, the primary cause of atmospheric global warming.

  16. Crystallization process of zircon and fergusonite during hydrothermal alteration in Nechalacho REE deposit, Thor Lake, Canada

    NASA Astrophysics Data System (ADS)

    Hoshino, M.; Watanabe, Y.; Murakami, H.; Kon, Y.; Tsunematsu, M.

    2012-04-01

    The core samples of two drill holes, which penetrate sub-horizontal mineralized horizons at Nechalacho REE deposit in the Proterozoic Thor Lake syenite, Canada, were studied in order to clarify magmatic and hydrothermal processes that enriched HFSE (e.g. Zr, Nb, Y and REE). Zircon is the most common REE minerals in Nechalacho REE deposit. The zircon is divided into five types as follows: Type-1 zircon occurs as single grain in phlogopite and the chondrite-normalized REE pattern is characterized by a steeply-rising slope from the LREE to the HREE with a positive Ce-anomaly and negative Eu-anomaly. This chemical characteristic is similar to that of igneous zircon. Type-2 zircon consists of HREE-rich magmatic porous core and LREE-Nb-F-rich hydrothermal rim. This type zircon is mostly included in phlogopite and fluorite, and occasionally in microcline. Type-3 zircon is characterized by euhedral to anhedral crystal, occurring in a complex intergrowth with REE fluorocarbonates. Type-3 zircons have high contents of REE, Nb and fluorine. Type-4 zircon consists of porous-core and -rim zones, but their chemical compositions are similar to each other. This type zircon is a subhedral crystal rimmed by fergusonite. Type-5 zircon is characterized by smaller, porous and subhedral to anhedral crystals. The interstices between small zircons are filled by fergusonite. Type-4 and -5 zircons show low REE and Nb contents. Occurrences of these five types of zircon are different according to the depth and degree of the alteration by hydrothermal solutions rich in F- and CO3 of the two drill holes, which permit a model for evolution of the zircon crystallization in Nechalacho REE deposit as follows: (1) type-1 (single magmatic zircon) is formed in miaskitic syenite. (2) LREE-Nb-F-rich hydrothermal zircon formed around HREE-rich magmatic zircon (type-2 zircon); (3) type-3 zircon crystallized thorough F and CO3-rich hydrothermal alteration of type-2 zircon which formed the complex intergrowth with REE fluorocarbonates; (4) the CO3-rich hydrothermal fluid corroded type-3, forming Nb-REE-poor zircons (type-3). Niobium and REE was no longer stable in the zircon structure and crystallized as fergusonite around the REE-Nb-leached zircon (type-4); (5) type-5 zircons are formed from more CO3-rich hydrothermal alteration of type-3 zircon. Therefore, type-4 and -5 zircons are often included in ankerite. Type 3-5 zircons at Nechalacho REE deposit were formed by leaching and/or dissolution of type-2 zircon in the presence of F- and/or CO3-rich hydrothermal fluid. The above mineral association indicates that three hydrothermal stages were present and related to HFSE enrichment in the Nechalacho REE deposit: (1) F-rich hydrothermal stage caused the crystallization of REE-Nb-rich zircon (type-2 rim and type-3), with abundant formation of phlogophite and fluorite, (2) F-CO3-rich hydrothermal stage led to the replacement of a part of REE-Nb-F-rich zircon by REE fluorocarbonate and (3) hydrothermal stage rich in CO3 resulted in crystallization of REE-Nb-F-poor zircon and fergusonite, with ankerite. Increases of HFSE contents, REE-Nb-F-poor zircon (type-4 and -5) and fergusonite contents during progress of hydrothermal alteration show that REE and Nb in hydrothermal fluid in the Nechalacho REE deposit were finally concentrated into fergusonite by way of zircon.

  17. Composite propellant aluminum agglomeration reduction using tailored Al/PTFE particles

    NASA Astrophysics Data System (ADS)

    Sippel, Travis R.

    Micron aluminum is widely used in propellants; however, performance could be significantly improved if ignition barriers could be disrupted and combustion tailored. In solid propellants for example, aluminum increases theoretical specific impulse performance, yet theoretical levels cannot be achieved largely because of two-phase flow losses. These losses could be reduced if particles quickly ignited, more gaseous products were produced, and if particle breakup occurred during combustion. To achieve altered aluminum ignition and particle combustion, this work explores the use of low level (10-30 wt.%) fluorocarbon (polytetrafluoroethylene (PTFE) or poly(carbon monofluoride) (PMF)) inclusion inside of aluminum via low or high energy mechanical activation. Aluminum/PTFE particles are found to be amenable to use in binder based energetics, having average particle sizes ranging from 15 to 78 μm, ~2-7 m2/g, specific surface area, and combustion enthalpies as high as 20.2 kJ/g. Differential scanning calorimetry (DSC) experiments indicate high energy MA reduces both reaction and oxidation onset to ~440 °C that is far below aluminum alone. Safety testing shows these particles have high electrostatic discharge (ESD) (89.9-108 mJ), impact (> 213 cm), and friction (> 360 N) ignition thresholds. The idea of further increasing reactivity and increasing particle combustion enthalpy is explored by reducing fluorocarbon inclusion content to 10 wt.% and through the use of the strained fluorocarbon PMF. Combustion enthalpy and average particle size range from 18.9 to 28.5 kJ/g and 23.0 to 67.5 μm, respectively and depend on MA intensity, duration, and inclusion level. Specific surface areas are high (5.3 to 34.8 m2/g) and as such, Al/PMF particles are appropriate for energetic applications not requiring a curable liquid binder. Mechanical activation reduces oxidation onset (DSC) from 555 to 480 °C (70/30 wt.%). Aluminum/PMF particles are sensitive to ESD (11.5-47.5 mJ) and some can be ignited via optical flash. Propellant aluminum agglomeration is assessed through replacement of reference aluminum powders (spherical, flake, or nanoscale) with Al/PTFE (90/10 or 70/30 wt.%) particles. The effects on burning rate, pressure dependence, and aluminum ignition, combustion, and agglomeration are quantified. Microscopic imaging shows tailored particles promptly ignite at the burning surface and appear to breakup into smaller particles. Replacement of spherical aluminum with Al/PTFE 70/30 wt.% also increases the pressure exponent from 0.36 to 0.58, which results in a 50% increase in propellant burning rate at 13.8 MPa. Combustion products were quench collected using a liquid-free technique at 2.1 and 6.9 MPa. Sizing of products indicates that composite particles result in nominally 25 μm coarse products, which are smaller than the original, average particle size and are also 66% smaller in diameter (96% by volume) than the 76 μm products collected from reference spherical aluminized propellant. Smaller diameter condensed phase products and more gaseous products will likely decrease two-phase flow loss and reduce slag accumulation in solid rocket motors.

  18. Photochemical modification of polyethylene terephthalate surface

    NASA Astrophysics Data System (ADS)

    Zhu, Zhengmao

    The prospect of obtaining desired surface-mediated characteristics while retaining bulk-mediated physical properties and avoiding potential environmental issues with wet chemical technology lends considerable appeal to photochemical approaches to surface modification. We undertook a combined experimental and computational approach to investigate the effect of deep UV irradiation on the polyethylene terephthalate (PET) surface. Its response to 172 nm UV from a xenon examiner lamp in the absence of oxygen was characterized with X-ray Photoelectron Spectroscopy (XPS), Time of Flight/Secondary Ion Mass Spectrometry (ToF/SIMS), transmission infrared spectroscopy (IR), and Atomic Force Microscopy (AFM). The surface chemistry details suggested that the primary photochemical reactions involved a Norrish type I based decarbonylation and a Norrish type II process yielding terminal carboxylic acid groups, consistent with the possible photochemistry from n-pi* type lowest singlet excited states of PET according to the computational modeling results. By directly populating n-pi* type excited states, 172 nm UV promoted effective surface photochemistry of PET with further helps from the high UV absorptivity and the high surface mobility of the molecules. Utilizing this active surface radical chemistry, a new grafting strategy was developed to impart desirable functional properties to the surface. A broad range of grafting chemicals can be employed in their vapor forms, demonstrated with an alkene or an alkane. Surface analysis with XPS, ToF/SIMS, AFM, and water contact angle measurements confirmed the effectiveness of the approach, supporting the notion of the surface radical initiated processes. A potentially useful anti-stain/soil coating was developed by grafting with a fluorocarbon species. Surface analysis suggested that the grafted fluorocarbon formed a nano-scale self-assembled monolayer. The coating had a similar water contact angle as that of a pure fluoropolymer but a better oil repellency due to the special molecular orientation in the graft layer. A potential antimicrobial application was demonstrated with amine chemicals. Structure characterization and computational modeling results suggested that the photochemistry of the UV active grafting chemicals also played an important role in the grafting process. A double bond structure in the amine species protected the amine functional groups and the resulting coating demonstrated antimicrobial activity against E. coli.

  19. Calibration and Sequence Development Status for the Sample Analysis at Mars Investigation on the Mars Science Laboratory

    NASA Technical Reports Server (NTRS)

    Mahaffy, Paul R.

    2012-01-01

    The measurement goals of the Sample Analysis at Mars (SAM) instrument suite on the "Curiosity" Rover of the Mars Science Laboratory (MSL) include chemical and isotopic analysis of organic and inorganic volatiles for both atmospheric and solid samples [1,2]. SAM directly supports the ambitious goals of the MSL mission to provide a quantitative assessment of habitability and preservation in Gale crater by means of a range of chemical and geological measurements [3]. The SAM FM combined calibration and environmental testing took place primarily in 2010 with a limited set of tests implemented after integration into the rover in January 2011. The scope of SAM FM testing was limited both to preserve SAM consumables such as life time of its electromechanical elements and to minimize the level of terrestrial contamination in the SAM instrument. A more comprehensive calibration of a SAM-like suite of instruments will be implemented in 2012 with calibration runs planned for the SAM testbed. The SAM Testbed is nearly identical to the SAM FM and operates in a ambient pressure chamber. The SAM Instrument Suite: SAM's instruments are a Quadrupole Mass Spectrometer (QMS), a 6-column Gas Chromatograph (GC), and a 2-channel Tunable Laser Spectrometer (TLS). Gas Chromatography Mass Spectrometry is designed for identification of even trace organic compounds. The TLS [5] secures the C, H, and O isotopic composition in carbon dioxide, water, and methane. Sieved materials are delivered from the MSL sample acquisition and processing system to one of68 cups of the Sample Manipulation System (SMS). 59 of these cups are fabricated from inert quartz. After sample delivery, a cup is inserted into one of 2 ovens for evolved gas analysis (EGA ambient to >9500C) by the QMS and TLS. A portion of the gas released can be trapped and subsequently analyzed by GCMS. Nine sealed cups contain liquid solvents and chemical derivatization or thermochemolysis agents to extract and transform polar molecules such as amino acids, nucleobases, and carboxylic acids into compounds that are sufficiently volatile to transmit through the GC columns. The remaining 6 cups contain calibrants. SAM FM Calibration Overview: The SAM FM calibration in the Mars chamber employed a variety of pure gases, gas mixtures, and solid materials. Isotope calibration runs for the TLS utilized 13C enriched C02 standards and 0 enriched CH4. A variety of fluorocarbon compounds that spanned the entire mass range of the QMS as well as C3-C6 hydrocarbons were utilized for calibration of the GCMS. Solid samples consisting of a mixture of calcite, melanterite, and inert silica glass either doped or not with fluorocarbons were introduced into the SAM FM cups through the SAM inlet funnel/tube system.

  20. Efficient, environmentally acceptable method for waterproofing insulation material

    NASA Technical Reports Server (NTRS)

    Blohowiak, Kay Y. (Inventor); Krienke, Kenneth A. (Inventor); Olli, Larry K. (Inventor); Newquist, Charles W. (Inventor)

    2000-01-01

    A process of waterproofing alumina-rich or silica-rich fibrous thermal insulation material, the process including the steps of: (a) providing an alumina-rich or a silica-rich fibrous material; (b) providing a waterproofing solution including: (1) a carrier solvent selected from the group consisting of aliphatic alcohols having from 1C to 6C, water, and mixtures thereof; and (2) an alkoxysilane defined by the formula R.sub.4-x -Si-(O-R').sub.x where x is 1-3 and R is selected from the group consisting of alkyl groups having from 1C to 10C, hydrogen, or fluorocarbon groups having from 1F to 15F; and where O-R' is an alkoxy group having from 1C to 5C, or a mixture of alkoxysilanes defined by the above formula R.sub.4-x -Si-(O-R').sub.x ; and optionally (3) modifiers including acids, such as acetic acid or nitric acid, or bases, such as ammonium hydroxide, RNH.sub.2, R.sub.2 NH, or R.sub.3 N, or MOH, where R is selected from the group consisting of alkyl groups having from 1C to 10C or hydrogen, and where M=Na, Li, or K; (c) contacting the fibrous material with the waterproofing solution for a sufficient amount of time to waterproof the fibrous material; and (d) curing the coated fibrous material to render it sufficiently waterproof. A chemical solution for waterproofing alumina-rich or silica-rich fibrous thermal insulation materials, the solution including: (a) a carrier solvent selected from the group consisting of aliphatic alcohols having from 1C to 6C, water, and mixtures thereof; and (b) an alkoxysilane defined by the formula R.sub.4-x -Si-(O-R').sub.x where x is 1-3 and R is selected from the group consisting of alkyl groups having from 1C to 10C, hydrogen, or fluorocarbon groups having from 1F to 15F; and where O-R' is an alkoxy group having from 1C to 5C, or a mixture of alkoxysilanes defined by the above formula R.sub.4-x -Si-(O-R').sub.x ; and optionally (c) modifiers including acids, such as acetic acid or nitric acid, or bases, such as ammonium hydroxide, RNH.sub.2, R.sub.2 NH, or R.sub.3 N, or MOH, where R is selected from the group consisting of alkyl groups having from 1C to 10C or hydrogen, and where M=Na, Li, or K.

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

    NASA Astrophysics Data System (ADS)

    Barry, Peter R.

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

  2. Rates and mechanisms of optic contamination in the EUV engineering test stand

    NASA Astrophysics Data System (ADS)

    Grunow, Philip A.; Klebanoff, Leonard E.; Graham, Samuel, Jr.; Haney, Steven J.; Clift, W. Miles

    2003-06-01

    The EUV Engineering Test Stand (ETS) is a full field, alpha class Extreme Ultraviolet Lithography (EUVL) tool that has demonstrated the printing of 70 nm resolution scanned images. The tool employs Mo/Si multilayer optics that reflect EUV radiation (13.4nm / 92.5eV) with ~67% peak reflectance per optic. For good reflectivity, many (greater than or equal to 40)Mo/Si layers must be present. Consequently, processes such as plasma induced multilayer erosion, which reduces the number of bilayer pairs on plasma facing optics, need to be understood. Since most materials readily absorb EUV photons, it is important to prevent contamination of mirror surfaces with EUV absorbing material. Contamination can occur by EUV photons "cracking" hydrocarbons or other species absorbed on the optical surfaces. The first ETS condenser component, referred to as C1, is coated with Mo/Si multilayers. Data collected from Mo/Si witness plates placed at the C1 position indicate erosion, using the Xe Laser Produced Plasma (LPP) spray jet, of 1 bilayer per ~15 million shots. Preliminary experiments with a filament jet yielded a significantly higher erosion rate. In the spray jet studies, erosion was found to depend sensitively on the composition of the residual background environment. Addition of low levels, ~7x10-7 Torr, of H2O to the vacuum background produced oxidation of the Si cap, and significantly slowed spray jet induced erosion. Operation of the plasma changed the environment in the Illuminator Chamber from oxidizing to carbonizing, thereby changing the nature of the contamination found environment at the C3 optic which does not view the plasma directly (and therefore does not erode). The change in environment is attributed to plasma induced outgassing of fluorocarbons in the Illuminator. Due to the non zero conductance between the Illuminator and Main Chambers, fluorocarbons were also found in the Main Chamber during Xe LPP operation. RGA data are presented that document the effect. In the presence of such outgassing, Carbon deposition rates were measured for the C3, and P.O. Box optics. For C3, a C deposition rate of 3 angstrom / 10 million shots was found, while for the PO Box, a C deposition rate of 0.02 angstrom / 10 million shots was found from the data. All data was acquired with no attempt to mitigate C deposition with gas phase additives such as O2.

  3. Rates and mechanisms of optic contamination in the EUVL engineering test stand

    NASA Astrophysics Data System (ADS)

    Grunow, Philip A.; Klebanoff, Leonard E.; Graham, Samuel, Jr.; Haney, Steven J.; Clift, W. Miles

    2003-06-01

    The EUV Engineering Test Stand (ETS) is a full-field, alpha-class Extreme Ultraviolet Lithography (EUVL) tool that has demonstrated the printing of 70 nm resolution scanned images. The tool employs Mo/Si multilayer optics that reflect EUV radiation (13.4nm / 92.5eV) with ~67% peak reflectance per optic. For good reflectivity, many (≥40)Mo/Si layers must be present. Consequently, processes such as plasma-induced multilayer erosion, which reduces the number of bilayer pairs on plasma-facing optics, need to be understood. Since most materials readily absorb EUV photons, it is important to prevent contamination of mirror surfaces with EUV absorbing material. Contamination can occur by EUV photons "cracking" hydrocarbons or other species absorbed on the optical surfaces. The first ETS condenser component, referred to as C1, is coated with Mo/Si multilayers. Data collected from Mo/Si witness plates placed at the C1 position indicate erosion, using the Xe Laser Produced Plasma (LPP) spray jet, of 1 bilayer per ~15 million shots. Preliminary experiments with a filament jet yielded a significantly higher erosion rate. In the spray jet studies, erosion was found to depend sensitively on the composition of the residual background environment. Addition of low levels, ~7x10-7 Torr, of H2O to the vacuum background produced oxidation of the Si cap, and significantly slowed spray jet-induced erosion. Operation of the plasma changed the environment in the Illuminator Chamber from oxidizing to carbonizing, thereby changing the nature of the contamination found environment at the C3 optic which does not view the plasma directly (and therefore does not erode). The change in environment is attributed to plasma-induced outgassing of fluorocarbons in the Illuminator. Due to the non-zero conductance between the Illuminator and Main Chambers, fluorocarbons were also found in the Main Chamber during Xe LPP operation. RGA data are presented that document the effect. In the presence of such outgassing, Carbon deposition rates were measured for the C3, and P.O. Box optics. For C3, a C deposition rate of 3 Å / 10 million shots was found, while for the PO Box, a C deposition rate of 0.02 Å / 10 million shots was found from the data. All data was acquired with no attempt to mitigate C deposition with gas-phase additives such as O2.

  4. Damage by radicals and photons during plasma cleaning of porous low-k SiOCH. II. Water uptake and change in dielectric constant

    SciTech Connect

    Shoeb, Juline; Kushner, Mark J.

    2012-07-15

    Porous dielectric materials provide lower capacitances that reduce RC time delays in integrated circuits. Typical low-k materials include porous SiOCH-silicon dioxide with carbon groups, principally CH{sub 3}, lining the pores. With a high porosity, internally connected pores provide pathways for reactive species to enter into the material. Fluorocarbon plasmas are often used to etch SiOCH, a process that leaves a fluorocarbon polymer on the surface that must later be removed. During cleaning using Ar/O{sub 2} or He/H{sub 2} plasmas, reactions of radicals that diffuse into the SiOCH and photons that penetrate into the SiOCH can remove -CH{sub 3} groups. Due to its higher reactivity, cleaning with Ar/O{sub 2} plasmas removes more -CH{sub 3} groups than He/H{sub 2} plasmas, and so produce more free radical sites, such as -SiO{sub 2} Bullet (a -SiO{sub 2}-CH{sub 3} site with the -CH{sub 3} group removed).Upon exposure to humid air, these free radical sites can chemisorb H{sub 2}O to form hydrophilic Si-OH which can further physisorb H{sub 2}O through hydrogen bonding to form Si-OH(H{sub 2}O). With the high dielectric constant of water, even a small percentage of water uptake can significantly increase the effective dielectric constant of SiOCH. In this paper, we report on results from a computational investigation of the cleaning of SiOCH using Ar/O{sub 2} or He/H{sub 2} plasmas and subsequent exposure to humid air. The authors found that plasma cleaning with He/H{sub 2} mixtures produce less demethylation than cleaning with Ar/O{sub 2} plasmas, as so results in less water uptake, and a smaller increase in dielectric constant. The water that produces the increase in dielectric constant is roughly half chemisorbed and half physisorbed, the latter of which can be removed with mild heating. Sealing the pores with NH{sub 3} plasma treatment reduces water uptake and helps prevent the increase in dielectric constant.

  5. Solvent organization around the perfluoro group of coumarin 153 governs its photophysical properties: An experimental and simulation study of coumarin dyes in ethanol as well as fluorinated ethanol solvents

    NASA Astrophysics Data System (ADS)

    Mondal, Saptarsi; Halder, Ritaban; Biswas, Biswajit; Jana, Biman; Singh, Prashant Chandra

    2016-05-01

    The self-aggregation property of the perfluoro group containing molecules makes it important in the research fields of biology and polymer and organic synthesis. In the quest of understanding the role of the perfluoro group on the photophysical properties of perfluoro-containing molecules in biologically important fluoroethanol solvents, we have applied photophysical as well as molecular dynamics simulation techniques to explore the properties of perfluoro groups containing molecule coumarin-153 (C153) in ethanol (ETH), monofluoroethanol (MFE), difluoroethanol (DFE), and trifluoroethanol (TFE) and compared them with the molecules without perfluoro moiety, namely coumarin-6H (C6H) and coumarin-480 (C480). In contrast to C6H and C480, the excited state lifetime of C153 in fluorinated ETHs is not monotonic. The excited state lifetime of C153 decreases in MFE and DFE as compared to ETH, whereas in TFE, it increases as compared to MFE and DFE. Molecular dynamics simulation reveals that the carbon terminal away from the OH group of fluorinated ETHs has a preferential orientation near the perfluoro (CF3) group of C153. In MFE and DFE, the CF3 group of C153 prefers to have a CF2—F⋯H —(CHF) type of electrostatic interaction over CF2—F⋯F —(CH2) kind of dispersion interaction which increases the rate of nonradiative decay, probably due to the electrostatic nature of the CF2—F⋯H —(CHF) hydrogen bond. On the other hand, in TFE, C—F⋯ F—C type of dispersion interaction, also known as fluorous interaction, takes place between the CF3 groups of C153 and TFE which decreases the rate of nonradiative rate as compared to MFE and DFE, leading to the increased lifetime of C153 in TFE. Photophysical and MD simulation studies clearly depict that the structural organization of solvents and their interaction with the fluorocarbon group are crucial factors for the photophysical behavior of the fluorocarbon containing molecules.

  6. Synthesis of hybrid inorganic/organic nitric oxide-releasing silica nanoparticles for biomedical applications

    NASA Astrophysics Data System (ADS)

    Carpenter, Alexis Wells

    Nitric oxide (NO) is an endogenously produced free radical involved in a number of physiological processes. Thus, much research has focused on developing scaffolds that store and deliver exogenous NO. Herein, the synthesis of N-diazeniumdiolate-modified silica nanoparticles of various physical and chemical properties for biomedical applications is presented. To further develop NO-releasing silica particles for antimicrobial applications, a reverse microemulsion synthesis was designed to achieve nanoparticles of distinct sizes and similar NO release characteristics. Decreasing scaffold size resulted in improved bactericidal activity against Pseudomonas aeruginosa. Confocal microscopy revealed that the improved efficacy resulted from faster particle-bacterium association kinetics. To broaden the therapeutic potential of NO-releasing silica particles, strategies to tune NO release characteristics were evaluated. Initially, surface hydrophobicity and NO release kinetics were tuned by grafting hydrocarbon- and fluorocarbon-based silanes onto the surface of N-diazeniumdiolate-modified particles. The addition of fluorocarbons resulted in a 10x increase in the NO release half-life. The addition of short-chained hydrocarbons to the particle surface increased their stability in hydrophobic electrospun polyurethanes. Although NO release kinetics were longer than that of unmodified particles, durations were still limited to <7 days. An alternative strategy for increasing NO release duration involved directly stabilizing the N-diazeniumdiolate using O2-protecting groups. O2-Methoxymethyl 1-(4-(3-(trimethoxysilyl)propyl))piperazin-1-yl)diazen-1-ium-1,2-diolate (MOM-Pip/NO) was grafted onto mesoporous silica nanoparticles to yield scaffolds with an NO payload of 2.5 μmol NO/mg and an NO release half-life of 23 d. Doping the MOM-Pip/NO-modified particles into resin composites yielded antibacterial NO-releasing dental restorative materials. A 3-log reduction in viable adhered Streptococcus mutans was observed with the MOM-Pip/NO-doped composites compared to undoped controls. The greater chemical flexibility of macromolecular scaffolds is a major advantage over LMW NO donors as it allows for the incorporation of multiple functionalities onto a single scaffold. To demonstrate this advantage, dual functional particles were synthesized by covalently binding quaternary ammonium (QA) functionalities to the surface of NO-releasing silica particles. The QA functionality proved more effective against Staphylococcus aureus than P. aeruginosa, and increasing alkyl chain length correlated with increased efficacy. Nitric oxide-releasing QA-functionalized particles were found to be more effective against S. aureus compared to monofunctional particles.

  7. Geochemical and mineralogical characteristics of ion-adsorption type REE mineralization in Phuket, Thailand

    NASA Astrophysics Data System (ADS)

    Sanematsu, Kenzo; Kon, Yoshiaki; Imai, Akira; Watanabe, Koichiro; Watanabe, Yasushi

    2013-04-01

    Geochemical and mineralogical studies were conducted on the 12-m-thick weathering profile of the Kata Beach granite in Phuket, Thailand, in order to reveal the transport and adsorption of rare earth elements (REE) related to the ion-adsorption type mineralization. The parent rock is ilmenite-series biotite granite with transitional characteristics from I type to S type, abundant in REE (592 ppm). REE are contained dominantly in fluorocarbonate as well as in allanite, titanite, apatite, and zircon. The chondrite-normalized REE pattern of the parent granite indicates enrichment of LREE relative to HREE and no significant Ce anomaly. The upper part of the weathering profile from the surface to 4.5 m depth is mostly characterized by positive Ce anomaly, showing lower REE contents ranging from 174 to 548 ppm and lower percentages of adsorbed REE from 34% to 68% compared with the parent granite. In contrast, the lower part of the profile from 4.5 to 12 m depth is characterized by negative Ce anomaly, showing higher REE contents ranging from 578 to 1,084 ppm and higher percentages from 53% to 85%. The negative Ce anomaly and enrichment of REE in the lower part of the profile suggest that acidic soil water in an oxidizing condition in the upper part mostly immobilized Ce4+ as CeO2 and transported REE3+ downward to the lower part of the profile. The transported REE3+ were adsorbed onto weathering products or distributed to secondary minerals such as rhabdophane. The immobilization of REE results from the increase of pH due to the contact with higher pH groundwater. Since the majority of REE in the weathered granite are present in the ion-adsorption fraction with negative Ce anomaly, the percentages of adsorbed REE are positively correlated with the whole-rock negative Ce anomaly. The result of this study suggests that the ion-adsorption type REE mineralization is identified by the occurrence of easily soluble REE fluorocarbonate and whole-rock negative Ce anomaly of weathered granite. Although fractionation of REE in weathered granite is controlled by the occurrence of REE-bearing minerals and adsorption by weathering products, the ion-adsorption fraction tends to be enriched in LREE relative to weathered granite.

  8. The Nolans Bore rare-earth element-phosphorus-uranium mineral system: geology, origin and post-depositional modifications

    NASA Astrophysics Data System (ADS)

    Huston, David L.; Maas, Roland; Cross, Andrew; Hussey, Kelvin J.; Mernagh, Terrence P.; Fraser, Geoff; Champion, David C.

    2016-01-01

    Nolans Bore is a rare-earth element (REE)-U-P fluorapatite vein deposit hosted mostly by the ~1805 Ma Boothby Orthogneiss in the Aileron Province, Northern Territory, Australia. The fluorapatite veins are complex, with two stages: (1) massive to granular fluorapatite with inclusions of REE silicates, phosphates and (fluoro)carbonates, and (2) calcite-allanite with accessory REE-bearing phosphate and (fluoro)carbonate minerals that vein and brecciate the earlier stage. The veins are locally accompanied by narrow skarn-like (garnet-diopside-amphibole) wall rock alteration zones. SHRIMP Th-Pb analyses of allanite yielded an age of 1525 ± 18 Ma, interpreted as the minimum age of mineralisation. The maximum age is provided by a ~1550 Ma SHRIMP U-Pb age for a pegmatite that predates the fluorapatite veins. Other isotopic systems yielded ages from ~1443 to ~345 Ma, implying significant post-depositional isotopic disturbance. Calculation of initial ɛNd and 87Sr/86Sr at 1525 Ma and stable isotope data are consistent with an enriched mantle or lower crust source, although post-depositional disturbance is likely. Processes leading to formation of Nolans Bore began with north-dipping subduction along the south margin of the Aileron Province at 1820-1750 Ma, producing a metasomatised, volatile-rich, lithospheric mantle wedge. About 200 million years later, near the end of the Chewings Orogeny, this reservoir and/or the lower crust sourced alkaline low-degree partial melts which passed into the mid- and upper-crust. Fluids derived from these melts, which may have included phosphatic melts, eventually deposited the Nolans Bore fluorapatite veins due to fluid-rock interaction, cooling, depressurisation and/or fluid mixing. Owing to its size and high concentration of Th (2500 ppm), in situ radiogenic heating caused significant recrystallisation and isotopic resetting. The system finally cooled below 300 °C at ~370 Ma, possibly in response to unroofing during the Alice Springs Orogeny. Surface exposure and weathering of fluorapatite produced acidic fluids and intense, near-surface kaolinitised zones that include high-grade, supergene-enriched cheralite-rich ores.

  9. Multi-functional Textiles for Military Applications

    NASA Astrophysics Data System (ADS)

    Malshe, Priyadarshini

    The objective of this research was to develop the standard rip-stop weave military uniform fabric made of 50/50 nylon/cotton (NyCo) to achieve a repellent front surface and an antibacterial bulk for protection from chemical-biological warfare agents. Diallyldimethylammonium chloride (DADMAC), a quaternary ammonium salt monomer was graft polymerized on NyCo fabric to impart antimicrobial capability using atmospheric pressure glow discharge plasma. Plasma was used to induce free radical chain polymerization of the DADMAC monomer to introduce a graft polymerized network on the fabric with durable antimicrobial properties. Pentaerythritol tertraacrylate was used as a cross-linking agent to obtain a highly cross-linked, durable polymer network. The presence of polyDADMAC on the fabric surface was confirmed using acid dye staining, SEM, and TOF-SIMS. Antibacterial performance was evaluated using standard AATCC test method 100 for both gram positive and gram negative bacteria. Results showed 99.9% reduction in the bacterial activities of K. pneumoniae and S. aureus. To achieve repellency on NyCo front surface, an environmentally benign C6 fluorocarbon monomer, 2-(perfluorohexyl) ethyl acrylate was graft polymerized using plasma on the front surface of the NyCo fabric which was already grafted with polyDADMAC for anti-microbial properties. The surface was characterized by IR spectroscopy and XPS. The presence of fluorine on the surface was mapped and confirmed by TOF-SIMS. SEM images showed a uniform layer of fluorocarbon polymer on the fiber surface. High water contact angle of 144° was obtained on the surface. The surface also achieved a high AATCC Test Method 193 rating of 9 and AATCC Test Method 118 rating of 5, indicating that the surface could repel a fluid with surface tension as low as 24 dynes/cm. Appropriate experimental designs and statistical modeling of data helped identify the experimental space and optimal factor combinations for best response. The study helped create a multi-functional fabric with an anti-bacterial bulk, hydrophilic back surface and repellent front surface for enhanced protective and aesthetic values.

  10. Diagnostic studies and modeling of inductively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Hsu, Cheng-Che

    The focus of this dissertation is the study of plasma-surface interactions and plasma chemistries through experimental approaches and numerical simulation. Various diagnostic studies and modeling of inductively coupled plasmas are described. Ruthenium etching with O2- and Cl2-containing ICP is studied. Ru etches readily in O2-containing plasmas. With Cl 2 addition, our observations include a significant increase in the etching rate, the detection of RuO4 at the downstream, the detection of RuOxCly ions in the plasma, and virtually zero wall deposition. Both O- and Cl-containing species (ions and/or neutrals) are necessary to explain the Cl2-addition effects. Diagnostic studies of Ar and octafluorocyclobutane plasmas are performed. The plasma species, the wall deposition rate, and the downstream species are quantified. Ar and F are the dominant radicals while CF+ and Ar+ appear to be the dominant ions. The detection of larger fluorocarbon ion species suggests the existence of larger fluorocarbon neutrals. The material balance shows over 30% of the incoming F- and C-containing species deposit on the chamber wall. Two OnWafer commercial plasma sensor systems are tested in the ICP system. Measurements of wafer temperature transients (using PlasmaTeMP(TM)) are compared to an energy transport model. Model predictions and measurements of transient wafer temperature profiles agree near-quantitatively, if details of the plasma heating sources and wafer characteristics are properly included. We outline a procedure to relate the temperature measurements to the surface ion flux profile. Measurements of the RF-current at the wafer surface (using PlasmaVolt(TM)) are shown to be approximately proportional to the square root of the electron density at the sheath edge. Comparisons of fluid model predictions with measurements in the ICP are reported. The model couples neutral flow, plasma, and electromagnetic equations. The gas chemistries used include Ar, Ar/O2, and Ar/O 2/Cl2. Measurements of electron density, EEPF, positive ion flux and its composition, and radical density at the wall are compared to corresponding model predictions. Radical and ion composition predictions are in good agreement for Ar and Ar/O2 plasmas, but the corresponding predictions in Ar/O2/Cl2 plasmas are in only partial agreement with measurements, implying that the chemical reaction database for this chemistry requires further work.

  11. Tris(Cyclopentadienyl)Uranium-t-Butyl: Synthesis, reactions, and mechanisms

    SciTech Connect

    Weydert, M.

    1993-04-01

    Compounds (RC[sub 5]H[sub 4])[sub 3]U(t-Bu) were prepared for R = H, Me, Et. Their decomposition products in aromatic solvents are consistent with a radical decomposition pathway induced by solvent-assisted U-C bond homolysis. NMR was used to study the reactions of (RC[sub 5]H[sub 4])[sub 3]UCl with t-BuLi (R = t-Bu, Me[sub 3]Si). Reactions of (MeC[sub 5]H[sub 4])[sub 3]U(t-Bu) with Lewis bases and fluorocarbons were studied. Analogous reaction chemistry between (RC[sub 5]H[sub 4])[sub 3]ThX systems and t-BuLi was also studied, and reactivity differences between U and Th are discussed. Synthesis of sterically crowded (RC[sub 5]H[sub 4])[sub 4]U compounds is next considered. Reaction of the trivalent (RC[sub 5]H[sub 4])[sub 3]U with (RC[sub 5]H[sub 4])[sub 2]Hg results in formation of (RC[sub 5]H[sub 4])[sub 4]U. Steric congestion, cyclopentadienyl ligand exchange, and electron transfer are discussed. (DLC)

  12. Tris(Cyclopentadienyl)Uranium-t-Butyl: Synthesis, reactions, and mechanisms

    SciTech Connect

    Weydert, M.

    1993-04-01

    Compounds (RC{sub 5}H{sub 4}){sub 3}U(t-Bu) were prepared for R = H, Me, Et. Their decomposition products in aromatic solvents are consistent with a radical decomposition pathway induced by solvent-assisted U-C bond homolysis. NMR was used to study the reactions of (RC{sub 5}H{sub 4}){sub 3}UCl with t-BuLi (R = t-Bu, Me{sub 3}Si). Reactions of (MeC{sub 5}H{sub 4}){sub 3}U(t-Bu) with Lewis bases and fluorocarbons were studied. Analogous reaction chemistry between (RC{sub 5}H{sub 4}){sub 3}ThX systems and t-BuLi was also studied, and reactivity differences between U and Th are discussed. Synthesis of sterically crowded (RC{sub 5}H{sub 4}){sub 4}U compounds is next considered. Reaction of the trivalent (RC{sub 5}H{sub 4}){sub 3}U with (RC{sub 5}H{sub 4}){sub 2}Hg results in formation of (RC{sub 5}H{sub 4}){sub 4}U. Steric congestion, cyclopentadienyl ligand exchange, and electron transfer are discussed. (DLC)

  13. Tribological properties of alkylsilane self-assembled monolayers.

    PubMed

    Lorenz, Christian D; Chandross, Michael; Grest, Gary S; Stevens, Mark J; Webb, Edmund B

    2005-12-01

    In this study, we perform molecular dynamics simulations of adhesive contact and friction between alkylsilane Si(OH)(3)(CX(2))(10)CX(3) and alkoxylsilane Si(OH)(2)(CX(2))(10)CX(3) (where X = H or F) self-assembled monolayers (SAMs) on an amorphous silica substrate. The alkylsilane SAMs are primarily hydrogen-bonded or physisorbed to the surface. The alkoxylsilane SAMs are covalently bonded or chemisorbed to the surface. Previously, we studied the chemisorbed systems. In this work, we study the physisorbed systems and compare the tribological properties with the chemisorbed systems. Furthermore, we examine how water at the interface of the SAMs and substrate affects the tribological properties of the physisorbed systems. When less than a third of a monolayer is present, very little difference in the microscopic friction coefficient mu or shear stresses is observed. For increasing amounts of water, the values of mu and the shear stresses decrease; this effect is somewhat more pronounced for fluorocarbon alkylsilane SAMs than for the hydrocarbon SAMs. The observed decrease in friction is a consequence of a slip plane that occurs in the water as the amount of water is increased. We studied the frictional behavior using relative shear velocities ranging from v = 2 cm/s to 2 m/s. Similar to previously reported results for alkoxylsilane SAMs, the values of the measured stress and mu for the alkylsilane SAM systems decrease monotonically with v. PMID:16316109

  14. Evaluation of HFC 245ca and HFC 236ea as foam blowing agents

    NASA Technical Reports Server (NTRS)

    Sharpe, Jon; Macarthur, Doug; Kollie, Tom; Graves, Ron; Liu, Matthew; Hendriks, Robert V.

    1995-01-01

    Hydrochlorofluorocarbon (HCFC) 141b has been selected as the interim blowing agent for use in urethane insulations on NASA's Space Shuttle External Tank. Due to the expected limited commercial lifetime of this material, research efforts at the NASA Thermal Protection Systems Materials Research Laboratory at the Marshall Space Flight Center are now being devoted to the identification and development of alternatives with zero ozone depletion potential. Physical blowing agents identified to date have included hydrocarbons, fluorocarbons, hydrofluoroethers, and more predominantly, hydrofluorocarbons (HFCs). The majority of the HFC evaluations in industry have focused on the more readily available, low boiling candidates such as HFC 134a. Higher boiling HFC candidates that could be handled at ambient conditions and use current processing equipment would be more desirable. This paper will describe results from a research program of two such candidate HFC's performed as a cooperative effort between Martin Marietta Manned Space Systems, the U.S. Environmental Protection Agency, and Oak Ridge National Laboratories. The purpose of this effort was to perform a cursory evaluation of the developmental HFC's 245ca and 236ea as blowing agents in urethane based insulations. These two materials were selected from screening tests of 37 C2, C3, and C4 isomers based on physical properties, atmospheric lifetime, flammability, estimated toxicity, difficulty of synthesis, suitability for dual use as a refrigerant, and other factors. Solubility of the two materials in typical foam components was tested, pour foaming trials were performed, and preliminary data were gathered regarding foam insulation performance.

  15. Regulation of adhesion behavior of murine macrophage using supported lipid membranes displaying tunable mannose domains.

    PubMed

    Kaindl, T; Oelke, J; Pasc, A; Kaufmann, S; Konovalov, O V; Funari, S S; Engel, U; Wixforth, A; Tanaka, M

    2010-07-21

    Highly uniform, strongly correlated domains of synthetically designed lipids can be incorporated into supported lipid membranes. The systematic characterization of membranes displaying a variety of domains revealed that the equilibrium size of domains significantly depends on the length of fluorocarbon chains, which can be quantitatively interpreted within the framework of an equivalent dipole model. A mono-dispersive, narrow size distribution of the domains enables us to treat the inter-domain correlations as two-dimensional colloidal crystallization and calculate the potentials of mean force. The obtained results demonstrated that both size and inter-domain correlation can precisely be controlled by the molecular structures. By coupling ?-D-mannose to lipid head groups, we studied the adhesion behavior of the murine macrophage (J774A.1) on supported membranes. Specific adhesion and spreading of macrophages showed a clear dependence on the density of functional lipids. The obtained results suggest that such synthetic lipid domains can be used as a defined platform to study how cells sense the size and distribution of functional molecules during adhesion and spreading. PMID:21399291

  16. Degradation of the materials of construction in Li-ion batteries

    SciTech Connect

    Braithwaite, J.W.; Gonzales, A.; Lucero, S.J.

    1997-03-01

    The primary current-collector materials being used in lithium-ion cells are susceptible to environmental degradation: aluminum to pitting corrosion and copper to environmentally assisted cracking. Pitting occurs at the highly oxidizing potentials associated with the positive-electrode charge condition. However, the pitting mechanism is more complex than that typically observed in aqueous systems in that the pits are filled with a mixed metal/oxide product and exist as mounds or nodules on the surface. Electrochemical impedance spectroscopy was shown to be an effective analytical tool for quantifying and verifying aluminum corrosion behavior. Two fluorocarbon-based coatings were shown to improve the resistance of Al to pitting attack. Detailed x-ray photoelectron spectroscopy (XPS) surface analyses showed that there was very little difference in the films observed after simple immersion in either PC:DEC or EC:DMC electrolytes versus those following electrical cycling. Li and P are the predominant surface species. Finally, environmental cracking of copper can occur at or near the lithium potential and only if specific metallurgical conditions exist (work-hardening and large grain size).

  17. Discrete elements for 3D microfluidics.

    PubMed

    Bhargava, Krisna C; Thompson, Bryant; Malmstadt, Noah

    2014-10-21

    Microfluidic systems are rapidly becoming commonplace tools for high-precision materials synthesis, biochemical sample preparation, and biophysical analysis. Typically, microfluidic systems are constructed in monolithic form by means of microfabrication and, increasingly, by additive techniques. These methods restrict the design and assembly of truly complex systems by placing unnecessary emphasis on complete functional integration of operational elements in a planar environment. Here, we present a solution based on discrete elements that liberates designers to build large-scale microfluidic systems in three dimensions that are modular, diverse, and predictable by simple network analysis techniques. We develop a sample library of standardized components and connectors manufactured using stereolithography. We predict and validate the flow characteristics of these individual components to design and construct a tunable concentration gradient generator with a scalable number of parallel outputs. We show that these systems are rapidly reconfigurable by constructing three variations of a device for generating monodisperse microdroplets in two distinct size regimes and in a high-throughput mode by simple replacement of emulsifier subcircuits. Finally, we demonstrate the capability for active process monitoring by constructing an optical sensing element for detecting water droplets in a fluorocarbon stream and quantifying their size and frequency. By moving away from large-scale integration toward standardized discrete elements, we demonstrate the potential to reduce the practice of designing and assembling complex 3D microfluidic circuits to a methodology comparable to that found in the electronics industry. PMID:25246553

  18. Tumor Oxygen Dynamics: Correlation of In Vivo MRI with Histological Findings1

    PubMed Central

    Zhao, Dawen; Ran, Sophia; Constantinescu, Anca; Hahn, Eric W; Mason, Ralph P

    2003-01-01

    Abstract Tumor oxygenation has long been recognized as a significant factor influencing cancer therapy. We recently established a novel magnetic resonance in vivo approach to measuring regional tumor oxygen tension, FREDOM (Fluorocarbon Relaxometry Using Echo Planar Imaging for Dynamic Oxygen Mapping), using hexafluorobenzene (HFB) as the reporter molecule. We have now investigated oxygen dynamics in the two Dunning prostate R3327 rat tumor sublines, AT1 and H. FREDOM revealed considerable intratumoral heterogeneity in the distribution of pO2 values in both sublines. The anaplastic fastergrowing AT1 tumors were more hypoxic compared with the size-matched, well-differentiated, and slower-growing H tumors. Respiratory challenge with oxygen produced significant increases in mean and median pO2 in all the H tumors (P<.001), but no response in half of the larger AT1 tumors (>3 cm3). Immunohistochemical studies using the hypoxia marker, pimonidazole, and the vascular endothelial cell marker, CD31, confirmed that the H tumors had more extensive vasculature and less hypoxia than the AT1 tumors. These results further validate the utilization of FREDOM to monitor tumor oxygenation and concur with the hypothesis that the level of hypoxia is related to tumor growth rate and poor vascularity. PMID:14511402

  19. Fast prototyping of injection molded polymer microfluidic chips

    NASA Astrophysics Data System (ADS)

    Steen Hansen, Thomas; Selmeczi, David; Larsen, Niels B.

    2010-01-01

    We present fast prototyping of injection molding tools by the definition of microfluidic structures in a light-curable epoxy (SU-8) directly on planar nickel mold inserts. Optimized prototype mold structures could withstand injection molding of more than 300 replicas in cyclic olefin copolymer (COC) without any signs of failure or release. The key parameters to avoid mold failure are maximum adhesion strength of the epoxy to the nickel insert and minimum interfacial energy of the epoxy pattern to the molded polymer. Optimal molding of microstructures with vertical sidewalls was found for nickel inserts pre-coated by silicon oxide before applying the structured epoxy, followed by coating of the epoxy by a fluorocarbon layer prior to injection molding. Further improvements in the mold stability were observed after homogeneous coating of the patterned epoxy by a second reflowed layer of epoxy, likely due to the resulting reduction in sidewall steepness. We employed the latter method for injection molding bondable polymer microfluidic chips with integrated conducting polymer electrode arrays that permitted the culture and on-chip analysis of cell spreading by impedance spectroscopy.

  20. A conformal oxidation-resistant, plasma-polymerized coating

    NASA Technical Reports Server (NTRS)

    Golub, Morton A.; Wydeven, Theodore; Lerner, Narcinda R.

    1991-01-01

    A comparative study was made of the surface recession (etching) of thin films of plasma polymerized tetrafluoro ethylene (PPTFE), polytetrafluoro ethylene (PTFE), and ion-beam sputter deposited polytetrafluoro ethylene (SPTFE) exposed to ground-state atomic oxygen downstream from a nonequilibrium radio-frequency O2 plasma. At 22 C, the etch rates for PTFE, SPTFE, and PPTFE were in the ratio of 8.7:1.8:1.0. A thin, conformal coating of PPTFE (etch rate of 0.3 nm/h at 22 C) was found to protect an underlying cast film of a reactive polymer, cis-1,4 polybutadiene, against ground-state atomic oxygen attack for the time required to fully etch away the PPTFE coating. From ESCA analysis, PTFE exhibited only minor surface oxidation (uptake of 0.5 atom percent O) upon etching, its F/C ratio decreasing slightly from 2.00 to 1.97; PPTFE exhibited considerable surface oxidation (uptake of 5.9 atom percent O) intermediate between those of PTFE and PPTFE, with a decrease in F/C ratio from 1.73 to 1.67. A plasma-polymerized fluorocarbon coating such as PPTFE might be useful for space applications to protect polymers that are vulnerable to oxidation or degradation by oxygen atoms.

  1. Bulk plasma fragmentation in a C4F8 inductively coupled plasma: A hybrid modeling study

    NASA Astrophysics Data System (ADS)

    Zhao, Shu-Xia; Zhang, Yu-Ru; Gao, Fei; Wang, You-Nian; Bogaerts, Annemie

    2015-06-01

    A hybrid model is used to investigate the fragmentation of C4F8 inductive discharges. Indeed, the resulting reactive species are crucial for the optimization of the Si-based etching process, since they determine the mechanisms of fluorination, polymerization, and sputtering. In this paper, we present the dissociation degree, the density ratio of F vs. CxFy (i.e., fluorocarbon (fc) neutrals), the neutral vs. positive ion density ratio, details on the neutral and ion components, and fractions of various fc neutrals (or ions) in the total fc neutral (or ion) density in a C4F8 inductively coupled plasma source, as well as the effect of pressure and power on these results. To analyze the fragmentation behavior, the electron density and temperature and electron energy probability function (EEPF) are investigated. Moreover, the main electron-impact generation sources for all considered neutrals and ions are determined from the complicated C4F8 reaction set used in the model. The C4F8 plasma fragmentation is explained, taking into account many factors, such as the EEPF characteristics, the dominance of primary and secondary processes, and the thresholds of dissociation and ionization. The simulation results are compared with experiments from literature, and reasonable agreement is obtained. Some discrepancies are observed, which can probably be attributed to the simplified polymer surface kinetics assumed in the model.

  2. Plasma-assisted nanoscale protein patterning on Si substrates via colloidal lithography.

    PubMed

    Malainou, A; Tsougeni, K; Ellinas, K; Petrou, P S; Constantoudis, V; Sarantopoulou, E; Awsiuk, K; Bernasik, A; Budkowski, A; Markou, A; Panagiotopoulos, I; Kakabakos, S E; Gogolides, E; Tserepi, A

    2013-12-19

    Selective immobilization of proteins in well-defined patterns on substrates has recently attracted considerable attention as an enabling technology for applications ranging from biosensors and BioMEMS to tissue engineering. In this work, a method is reported for low-cost, large scale and high throughput, selective immobilization of proteins on nanopatterned Si, based on colloidal lithography and plasma processing to define the areas (<300 nm) where proteins are selectively immobilized. A close-packed monolayer of PS microparticles is deposited on oxidized Si and, either after microparticle size reduction or alternatively after metal deposition through the PS close-packed monolayer, is used as etching mask to define SiO2 nanoislands (on Si). C4F8 plasma was used to selectively etch and modify the SiO2 nanoislands while depositing a fluorocarbon layer on the Si surface. The plasma-treated surfaces were chemically characterized in terms of functional group identification through XPS analysis and reaction with specific molecules. Highly selective protein immobilization mainly through physical adsorption on SiO2 nanoislands and not on surrounding Si was observed after C4F8 plasma-induced chemical modification of the substrate. The thickness of the immobilized protein monolayer was estimated by means of AFM image analysis. The method reported herein constitutes a cost-efficient route toward rapid, large surface, and high-density patterning of biomolecules on solid supports that can be easily applied in BioMEMS or microanalytical systems. PMID:24180245

  3. Simple fabrication of antireflective silicon subwavelength structure with self-cleaning properties.

    PubMed

    Kim, Bo-Soon; Ju, Won-Ki; Lee, Min-Woo; Lee, Cheon; Lee, Seung-Gol; Beom-Hoan, O

    2013-05-01

    A subwavelength structure (SWS) was formed via a simple chemical wet etching using a gold (Au) catalyst. Single nano-sized Au particles were fabricated by metallic self-aggregation. The deposition and thermal annealing of the thin metallic film were carried out. Thermal annealing of a thin metallic film enables the creation of metal nano particles by isolating them from each other by means of the self-aggregation of the metal. After annealing, the samples were soaked in an aqueous etching solution of hydrofluoric acid and hydrogen peroxide. When silicon (Si) was etched for 2 minutes using the Au nano particles, the reflectance was decreased almost 0% over the entire wavelength range from 300 to 1300 nm due to its deep and steeply double tapered structure. When given varying incident angle degrees from 30 degrees to 60 degrees, the reflectance was also maintained at less than 3%. Following this, the etched silicon was treated with a plasma-polymerized fluorocarbon (PPFC) film of about 5 nm using an ICP reactor for surface modification. The result of this surface treatment, the contact angle increased significantly from 27.5 degrees to 139.3 degrees. The surface modification was successful and maintained almost 0% reflectance because of the thin film deposition. PMID:23858915

  4. Improvement of feature-scale profile evolution in a silicon dioxide plasma etching simulator using the level set method

    NASA Astrophysics Data System (ADS)

    Montoliu, C.; Baer, E.; Cerdá, J.; Colom, R. J.

    2015-06-01

    We present a three-dimensional simulator of silicon dioxide etching in a fluorocarbon plasma process. Explicit parametrization of the surface is currently one of the most frequently used methods to evolve the etched surface according to the equipment simulation results. These techniques update the coordinates of the vertices and need to add and/or remove faces to keep an accurate surface representation. These processes can introduce errors and produce unrealistic results, especially in complex structures. In this paper we prove the effectiveness of our level set (LS) implementation to evolve the etched surface according to etching models, resulting in a fully operational plasma etching simulator. The LS implementation is based on a surface reconstruction algorithm from scattered points enabling the simulation of complex topological changes such as coalescing or splitting of contiguous regions. Additionally, our algorithm is based on the sparse field method for reducing computational time of the surface evolution process and it is perfectly suited to be used with the Anetch software package. Finally, several structures are simulated and an experimental result is used to compare and validate the effectiveness of the simulator we have developed.

  5. Comparison of CF4, CHF3 and CH2F2 plasmas used for wafer processing

    NASA Astrophysics Data System (ADS)

    Tinck, Stefan; Milenin, Alexey; Bogaerts, Annemie

    2012-10-01

    Fluorocarbon-based plasmas are widely used in the microelectronics industry for the fabrication of computer chips, i.e. in plasma etching of silicon. One such process is the etching of nanoscale trenches in the Si substrate with CHxFy plasmas as applied in shallow trench isolation (STI). By carefully altering the ratio between gases such as CF4, CHF3 and CH2F2, the overall etching process can be controlled in terms of chemical etching, sputtering and sidewall passivation. Therefore, we wish to obtain a more fundamental understanding of these plasmas and their surface processes. The plasma behavior will be simulated by a hybrid model for addressing the various plasma species, while the surface interactions of the plasma will be described by additional Monte Carlo simulations, allowing a detailed insight in the nanoscale trench etching process. Bulk plasma properties such as species densities, temperatures and fluxes towards the walls will be discussed under typical wafer processing conditions as well as surface properties including etch rate and chemical composition of the surface during trench etching. The etch rate and microscopic etch profiles will be compared with experimental data.

  6. Can Fluorinated Molecular Cages Be Utilized as Building Blocks of Hyperhalogens?

    PubMed

    Sun, Wei-Ming; Li, Xiang-Hui; Li, Ying; Wu, Di; Li, Chun-Yan; Chen, Jing-Hua; Li, Zhi-Ru

    2016-05-18

    Based on the density functional theory for exchange-correlation potential, fluorocarbon molecular cages are investigated as building blocks of hyperhalogens. By utilizing C8 F7 as a ligand, a series of hyperhalogen anions, that is, M(C8 F7 )2 (-) (M=Li, Na, and K) and M(C8 F7 )3 (-) (M=Be, Mg, and Ca), are modeled. Calculations show that all the C8 F7 moieties preserve their geometric and electronic integrity in these anions. These anionic molecules possess larger vertical electron detachment energies (5.11-6.45 eV) than that of C8 F7 (-) , verifying their hyperhalogen nature. Moreover, it is also revealed that using larger fluorinated cage C10 F9 as ligands can bring about hyperhalogen anions with larger vertical electron detachment energies. The stability of these studied anions is determined by their large HOMO-LUMO gaps and positive dissociation energies of predetermined possible fragmentation pathways. It is hoped this study will provide an approach for the construction of new types of hyperhalogens and stimulate more research in superatom chemistry. PMID:26923480

  7. Substrate and chain length dependencies of the thermal behavior of [CF3(CF2)m(CH2)nCOO]2Cd single monolayers investigated by infrared reflection absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Ren, Yanzhi; Asanuma, Morito; Iimura, Ken-ichi; Kato, Teiji

    2001-01-01

    Temperature-variable grazing incidence reflection absorption (GIR) spectra were recorded for the single monolayer of [CF3(CF2)m(CH2)nCOO)]2Cd [(m,n)=(7,10), (7,16), (7,22), (5,22), and (3,22)], transferred from aqueous Cd2+ subphase to gold- and aluminum-evaporated glass substrates. The spectra reveal that these monolayers have better thermal stability on Al substrates than on Au. An "interaction band" is identified at 1484˜1480 cm-1, due to the νs(COO-) mode of carboxylate headgroups in ionic bonding with the Al surface. It is found that both the van der Waals interaction between the trans zig-zag hydrocarbon chains and the overlapping interaction between the fluorocarbon helixes are responsible for the systematic variation of the monolayer thermal behavior with (m,n). The thermal behavior of a single monolayer of cadmium stearate, serving as a model system, has been investigated to further confirm the spectral interpretation about the partially fluorinated monolayer. In addition, temperature-dependent friction measurements show that the single monolayers of (m,n)=(7,16), (7,22), (5,22), and (3,22) are potential molecular lubricants that can be used in the range of 25˜140 °C.

  8. Global warming and end-use efficiency implications of replacing CFCs

    SciTech Connect

    Fairchild, P.D.; Fischer, S.K.

    1991-12-31

    The direct contribution of CFCs to calculated global warming has been recognized for some time. As a result of the international agreement to phase out CFCs due to stratospheric ozone and the ensuing search for suitable alternatives, there has recently been increased attention on the DIRECT global warming potential (GWP) of the fluorocarbon alternatives as greenhouse gases. However, to date there has been little focus on the INDIRECT global warming effect arising from end-use efficiency changes and associated CO{sub 2} emissions. A study being conducted at Oak Ridge National Laboratory (ORNL) addresses this combined or total global warming impact of viable options to replace CFCs in their major energy-related applications. This paper reviews selected results for air-conditioning, refrigeration, and heat pump applications. The analysis indicates that the CFC user industries have made substantial progress in approaching near-equal energy efficiency with the HCFC/HFC alternative refrigerants. The findings also bring into question the relative importance of the DIRECT (chemical-related) effect in many applications. Replacing CFCs is an important step in reducing the total global warming impact, and at present the HCFC and HFCS appear to offer the best efficiency and lowest total impact of options available in the relatively short time period required for the transition away from CFCs.

  9. Climate change and air pollution jointly creating nightmare for tourism industry.

    PubMed

    Sajjad, Faiza; Noreen, Umara; Zaman, Khalid

    2014-11-01

    The objective of the study is to examine the long-run and causal relationship between climate change (i.e., greenhouse gas emissions, hydrofluorocarbons, per fluorocarbons, and sulfur hexafluoride), air pollution (i.e., methane emissions, nitrous oxide emissions, and carbon dioxide emissions), and tourism development indicators (i.e., international tourism receipts, international tourism expenditures, natural resource depletion, and net forest depletion) in the World's largest regions. The aggregate data is used for robust analysis in the South Asia, the Middle East and North Africa, sub-Saharan Africa, and East Asia and the Pacific regions, over a period of 1975-2012. The results show that climatic factors and air pollution have a negative impact on tourism indicators in the form of deforestation and natural resource depletion. The impact is evident, as we have seen the systematic eroding of tourism industry, due to severe changes in climate and increasing strain of air pollution. There are several channels of cause-effect relationship between the climatic factors, air pollution, and tourism indicators in the World's region. The study confirms the unidirectional, bidirectional, and causality independent relationship between climatic factors, air pollution, and tourism indicators in the World. It is conclusive that tourism industry is facing all time bigger challenges of reduce investment, less resources, and minor importance from the government agencies because of the two broad challenges, i.e., climate change and air pollution, putting them in a dismal state. PMID:24938808

  10. Charge profiling and stability testing of biosimilar by capillary isoelectric focusing.

    PubMed

    Cao, Junzi; Sun, Wen; Gong, Feifei; Liu, Wanhui

    2014-05-01

    CIEF was developed for the rapid analysis of charge heterogeneity of trastuzumab biosimilar using commercially available fluorocarbon-coated capillary. The CIEF master mix was composed of 0.30% w/v methyl cellulose, 2.3 M urea, 56.8 mM l-arginine, 1.52 mM iminodiacetic acid, 4.5% v/v carrier ampholytes (broad-range pI 3-10 and narrow-range pI 8-10.5 with ratio of 3:1), and 0.45% v/v 10.0, 9.5, 7.0, 5.5, 4.1 pI markers. To get a robust method to analyze charge heterogeneity, some separation parameters, including focusing time and separation temperature, were investigated and optimized. The optimized method gave good precision in estimated pI values of charge variants with RSDs of not more than 0.16% intraday analysis (n = 6) and < 0.18% interday analysis (n = 9). In addition, the applications of this method including purity, stability, lot consistency, peptide N-glycosidase F digest, and C-terminal lysine variants characterization were also investigated. PMID:24610636

  11. Influence of sexual dimorphism on pulmonary inflammatory response in adult mice exposed to chloroform.

    PubMed

    de Oliveira, Túlio Henrique Versiani; Campos, Keila Karine Duarte; Soares, Nícia Pedreira; Pena, Karina Braga; Lima, Wanderson Geraldo; Bezerra, Frank Silva

    2015-01-01

    Chloroform is an organic solvent used as an intermediate in the synthesis of various fluorocarbons. Despite its widespread use in industry and agriculture, exposure to chloroform can cause illnesses such as cancer, especially in the liver and kidneys. The aim of the study was to analyze the effects of chloroform on redox imbalance and pulmonary inflammatory response in adult C57BL/6 mice. Forty animals were divided into 4 groups (N = 10): female (FCG) and male (MCG) controls, and females (FEG) and males (MEG) exposed to chloroform (7.0 ppm) 3 times/d for 20 minutes for 5 days. Total and differential cell counts, oxidative damage analysis, and protein carbonyl and antioxidant enzyme catalase (CAT) activity measurements were performed. Morphometric analyses included alveolar area (Aa) and volume density of alveolar septa (Vv) measurements. Compared to FCG and MCG, inflammatory cell influx, oxidative damage to lipids and proteins, and CAT activity were higher in FEG and MEG, respectively. Oxidative damage and enzyme CAT activity were higher in FEG than in FCG. The Aa was higher in FEG and MEG than in FCG and MCG, respectively. The Vv was lower in FEG and MEG than in FCG and MCG, respectively. This study highlights the risks of occupational chloroform exposure at low concentrations and the intensity of oxidative damage related to gender. The results validate a model of acute exposure that provides cellular and biochemical data through short-term exposure to chloroform. PMID:25870144

  12. Laboratory studies of chemical and photochemical processes relevant to stratospheric ozone

    NASA Technical Reports Server (NTRS)

    Zahniser, Mark S.; Nelson, David D.; Worsnop, Douglas R.; Kolb, Charles E.

    1994-01-01

    The purpose of this project is to reduce the uncertainty in several key gas-phase kinetic processes which impact our understanding of stratospheric ozone. The main emphasis of this work is on measuring rate coefficients and product channels for reactions of HO(sub x) and NO(sub x) species in the temperature range 200 K to 240 K relevant to the lower stratosphere. Other areas of study have included infrared spectroscopic studies of the HO2 radical, measurements of OH radical reactions with alternative fluorocarbons, and determination of the vapor pressures of nitric acid hydrates under stratospheric conditions. The results of these studies will improve models of stratospheric ozone chemistry and predictions of perturbations due to human influences. In this annual report, we focus on our recent accomplishments in the quantitative spectroscopy of the HO2 radical. This report details the measurements of the broadening coefficients for the v(sub 2) vibrational band. Further measurements of the vapor pressures of nitric acid hydrates relevant to the polar stratospheric cloud formation indicate the importance of metastable crystalline phases of H2SO4, HNO3, and H2O. Large particles produced from these metastable phases may provide a removal mechanism for HNO3 in the polar stratosphere.

  13. Interplay between mechanical, electrical, and thermal relaxations in nanocomposite proton conducting membranes based on Nafion and a [(ZrO2)·(Ta2O5)(0.119)] core-shell nanofiller.

    PubMed

    Di Noto, Vito; Piga, Matteo; Giffin, Guinevere A; Vezzù, Keti; Zawodzinski, Thomas A

    2012-11-21

    The thermal, mechanical, and electric properties of hybrid membranes based on Nafion that contain a [(ZrO(2))·(Ta(2)O(5))(0.119)] "core-shell" nanofiller are elucidated. DSC investigations reveal the presence of four endothermic transitions between 50 and 300 °C. The DMA results indicate improved mechanical stability of the hybrid materials. The DSC and DMA results are consistent with our previous suggestion of dynamic R-SO(3)H···[ZrTa] cross-links in the material. These increase the thermal stability of the -SO(3)H groups and the temperature of thermal relaxation events occurring in hydrophobic domains of Nafion. The broadband electrical spectroscopic analysis reveals two electric relaxations associated with the material's interfacial (σ(IP)) and bulk proton conductivities (σ(EP)). The wet [Nafion/(ZrTa)(1.042)] membrane has a conductivity of 7.0 × 10(-2) S cm(-1) at 115 °C, while Nafion has a conductivity of 3.3 × 10(-2) S cm(-1) at the same temperature and humidification conditions. σ(EP) shows VTF behavior, suggesting that the long-range conductivity is closely related to the segmental motion of the Nafion host matrix. Long-range conduction (σ(EP)) occurs when the dynamics of the fluorocarbon matrix induces contact between different delocalization bodies (DB), which results in proton exchange processes between these DBs. PMID:23102554

  14. Geographically distributed emissions of Ozone Depleting Substances in the year 2000

    NASA Astrophysics Data System (ADS)

    McCulloch, A.; Midgley, P. M.

    2003-04-01

    Based on the audited sales data from industry provided by the Alternative Fluorocarbons Environmental Acceptability Study (AFEAS) and consumption data from parties to the Montreal Protocol compiled by the United Nations Environment Programme (UNEP), estimates of the global consumption of chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs) and methyl chloroform have been made for each year up to 2000. Annual global emissions have been calculated from these data using standard emission functions that were tested against atmospheric concentrations. National shares of the global emissions have been calculated from the history of national consumption in the UNEP database. Subsequently, the national share has been distributed within each country using population density. Results in the form of the distribution of emissions mapped onto a 1 degree latitude by 1 degree longitude grid will be described for CFC-11, CFC-12, CFC-113, methyl chloroform and HCFC-22 in the year 2000. AFEAS was one of the founder members of the Network for Detection of Stratospheric Change (NDSC) and close links have been maintained. The aim of the work described is to produce verified data sets of atmospheric emissions for testing and improving multidimensional models

  15. Discrete elements for 3D microfluidics

    PubMed Central

    Bhargava, Krisna C.; Thompson, Bryant; Malmstadt, Noah

    2014-01-01

    Microfluidic systems are rapidly becoming commonplace tools for high-precision materials synthesis, biochemical sample preparation, and biophysical analysis. Typically, microfluidic systems are constructed in monolithic form by means of microfabrication and, increasingly, by additive techniques. These methods restrict the design and assembly of truly complex systems by placing unnecessary emphasis on complete functional integration of operational elements in a planar environment. Here, we present a solution based on discrete elements that liberates designers to build large-scale microfluidic systems in three dimensions that are modular, diverse, and predictable by simple network analysis techniques. We develop a sample library of standardized components and connectors manufactured using stereolithography. We predict and validate the flow characteristics of these individual components to design and construct a tunable concentration gradient generator with a scalable number of parallel outputs. We show that these systems are rapidly reconfigurable by constructing three variations of a device for generating monodisperse microdroplets in two distinct size regimes and in a high-throughput mode by simple replacement of emulsifier subcircuits. Finally, we demonstrate the capability for active process monitoring by constructing an optical sensing element for detecting water droplets in a fluorocarbon stream and quantifying their size and frequency. By moving away from large-scale integration toward standardized discrete elements, we demonstrate the potential to reduce the practice of designing and assembling complex 3D microfluidic circuits to a methodology comparable to that found in the electronics industry. PMID:25246553

  16. Prediction of ultraviolet-induced damage during plasma processes in dielectric films using on-wafer monitoring techniques

    SciTech Connect

    Ishikawa, Yasushi; Katoh, Yuji; Okigawa, Mitsuru; Samukawa, Seiji

    2005-11-15

    We measured electron-hole pairs generated in dielectric film using our developed on-wafer monitoring technique to detect electrical currents in the film during the plasma etching processes. The electron-hole pairs were generated by plasma induced ultraviolet (UV) photons, and the number of electron-hole pairs depends on the UV wavelength. In SiO{sub 2} film, UV light, which has a wavelength of less than 140 nm, generates electron-hole pairs, because the band gap energy of the film is 8.8 eV. On the other hand, in Si{sub 3}N{sub 4} film, which has a band gap energy level of 5.0 eV, UV light below 250 nm induces the electron-hole pairs. Additionally, we evaluated the fluorocarbon gas plasma process that induces UV radiation damage using multilayer sensors that consisted of both SiO{sub 2} and Si{sub 3}N{sub 4} stacked films. In these cases, electron-hole pair generation depended on the dielectric film structure. There were more electron-hole pairs generated in the SiO{sub 2} deposited on the Si{sub 3}N{sub 4} film than in the Si{sub 3}N{sub 4} deposited on the SiO{sub 2} film. As a result, our developed on-wafer monitoring sensor was able to predict electron-hole pair generation and the device characteristics.

  17. Langmuir Probe Measurements of Inductively Coupled Plasmas in CF4/Ar/O2 Mixtures

    NASA Technical Reports Server (NTRS)

    Rao, M. V. V. S.; Meyyappan, M.; Sharma, S. P.

    2000-01-01

    Fluorocarbon gases, such as CF4, and their mixtures are widely used in contemporary low-pressure and high-density plasma processing techniques. In such plasmas Langmuir probe is one of the most commonly employed diagnostic techniques to obtain electron number density (ne), electron temperature (Te), electron energy distribution function (EEDF), mean electron energy (Ee), ion number density (ni), and plasma potential (Vp). In this paper we report probe data for planar inductively coupled plasmas in CF4/O2/Ar mixtures. By varying the relative concentrations in the mixture, radial profiles of ne, ni, Te, Ee, Vp, EEDF were measured in the mid-plane of the plasma at 10 mTorr and 20 mTorr of gas pressures, and 200 W and 300 W of RF powers. Data show that ne and ni decrease with increase of CF4 content and decrease of gas-pressure but they increase with increase of RF-power, whereas Vp increases with decrease of gas-pressure and remains independent of RF-power. However, they all peak at the center of the plasma and decrease towards the edge while Te follows the other way and increases a little with increase of power. The measured EEDFs exhibit Druyvesteyn-like distribution at all pressures and powers. Data are analyzed and will be presented.

  18. Environmental fate of the next generation refrigerant 2,3,3,3-tetrafluoropropene (HFO-1234yf).

    PubMed

    Im, Jeongdae; Walshe-Langford, Gillian E; Moon, Ji-Won; Löffler, Frank E

    2014-11-18

    The hydrofluoroolefin 2,3,3,3-tetrafluoropropene (HFO-1234yf) has been introduced to replace 1,1,1,2-tetrafluoroethane (HFC-134a) as refrigerant in mobile, including vehicle, air conditioning systems because of its lower global warming potential. HFO-1234yf is volatile at ambient temperatures; however, high production volumes and widespread handling are expected to release this fluorocarbon into terrestrial and aquatic environments, including groundwater. Laboratory experiments explored HFO-1234yf degradation by (i) microbial processes under oxic and anoxic conditions, (ii) abiotic processes mediated by reactive mineral phases and zerovalent iron (Fe(0), ZVI), and (iii) cobalamin-catalyzed biomimetic transformation. These investigations demonstrated that HFO-1234yf was recalcitrant to microbial (co)metabolism and no transformation was observed in incubations with ZVI, makinawite (FeS), sulfate green rust (GR(SO4)), magnetite (Fe(3)O(4)), and manganese oxide (MnO2). Sequential reductive defluorination of HFO-1234yf to 3,3,3-trifluoropropene and 3,3-dichloropropene with concomitant stoichiometric release of fluoride occurred in incubations with reduced cobalamins (e.g., vitamin B12) indicating that biomolecules can transform HFO-1234yf at circumneutral pH and at ambient temperature. Taken together, these findings suggest that HFO-1234yf recalcitrance in aquifers should be expected; however, HFO-1234yf is not inert and a biomolecule may mediate reductive transformation in low redox environments, albeit at low rates. PMID:25329364

  19. A Roof for the Lion's House

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Fans of the National Football League's Detroit Lions don't worry about gameday weather. Their magnificent new Pontiac Stadium has a domed, air-supported, fabric roof that admits light but protects the playing field and patrons from the elements. The 80,000-seat "Silverdome" is the world's largest fabric-covered structure-and aerospace technology played an important part in its construction. The key to economical construction of the Silverdome-and many other types of buildings-is a spinoff of fiber glass Beta yarn coated with Teflon TFE fluorocarbon resin. The big advance it offers is permanency. Fabric structures-tents, for example have been around since the earliest years of human civilization. But their coverings-hides, canvas and more recently plastics-were considered temporary; though tough, these fabrics were subject to weather deterioration. Teflon TFE-coated Beta Fiberglas is virtually impervious to the effects of weather and sunlight and it won't stretch, shrink, mildew or rot, thus has exceptional longevity; it is also very strong, lightweight, flame resistant and requires no periodic cleaning, because dirt will not stick to the surface of Teflon TFE. And to top all that, it costs only 30 to 40 percent as much as conventional roofing.

  20. Roughness formation on photoresist during etching examined by HBr plasma-beam

    NASA Astrophysics Data System (ADS)

    Sekine, Makoto; Zhang, Yan; Ishikawa, Kenji; Takeda, Keigo; Kondo, Hiroki; Hori, Masaru; Plasma Nanotechnology Team

    2014-10-01

    For highly precise patterning in device fabrication, it is required to suppress roughness formations on photoresist (PR) polymers during plasma etching. HBr plasma treatment called ``plasma cure'' was proposed to reduce the roughness. By using a beam irradiation, we reported the PR roughness formation in fluorocarbon plasma, and the effect of HBr cure. We report the roughness formation mechanism by surface analyses and power spectral density (PSD) of the roughness. Average slope and roll-off frequency of PSD are characterized by frequency components, the high-frequency roughness. We treated the data for six samples: a) pristine, b) after Ar plasma irradiation, c) after Ar plasma followed by HBr cure, d) after HBr cure, e) after HBr followed by Ar plasma beam, and f) after HBr followed by H2 and Ar plasma beam irradiations. The PSD slopes were changed by each process. Based on the results, we speculated that the Ar-plasma beam formed a crust layer on the PR surface with unrelieved stress and HBr cure may soften the bulk PR to relieve the stress and cause agglomeration of polymers at the size over 10 nm.

  1. Modeling Surface Water Transport in the Central Pacific Ocean With 129I Records From Coral Skeletons

    NASA Astrophysics Data System (ADS)

    Beck, W.; Biddulph, D. L.; Russell, J. L.; Burr, G. S.; Jull, T. J.; Correge, T.; Roeder, B.

    2008-12-01

    129I occurs naturally in extremely low abundance via cosmic ray interactions in the atmosphere as well as by spontaneous fission of uranium. Oceanic concentrations of 129I have risen by several orders of magnitude during the last half century largely from environmental pollution coming from several point-source nuclear fuel reprocessing plants. In the Pacific basin, much of the increase has apparently come from the Hanford Nuclear reprocessing plant in the United States, with iodine primarily arriving via the Columbia River. Coral skeletons preserve records of 129I concentration of the surface waters from which they were deposited, yielding records with annual resolution or better. We will present three such records from different locations in the Pacific Ocean: the Solomon Islands, Easter Island and Clipperton Atoll. For this study, drill cores from living massive coral skeletons of the species Porites Lobata were collected from these sites. 129I/127I values were measured using accelerator mass spectrometry (AMS) at the University of Arizona with an NEC 3 MV Pelletron accelerator. Results from the analysis of the corals will be compared to the distribution of other mixed-layer tracers (chloro-fluorocarbons and tritium) collected during the World Ocean Circulation Experiment cruises conducted between 1990 and 2002. The 129I/127I records observed in these corals will also be compared to tracer transit time calculations determined from a 20th century simulation of the GFDL coupled-climate passive-tracer model.

  2. Metals fact sheet - samarium

    SciTech Connect

    1993-10-01

    The crustal abundance of samarium is 7 ppm, similar to that of praseodymium and gadolinium. About 50 percent of the total samarium oxide produced worldwide comes from the mining of monazite. Bastnasite accounts for approximately 40 percent of samarium oxide production, and the remaining 10 percent is derived from other rare earth minerals such as xenotime, apatite, loparite, and rare earth clays. Monazite is usually found in alluvial or beach deposits associated with other heavy minerals, typically rutile and zircon, and is recovered by suction dredging or bucket wheel excavation. The heavy minerals are subsequently separated by gravity, magnetic, and/or electrostatic means, and the resulting monazite concentrate undergoes a series of caustic and acid leaching steps to isolate the rare earths. Bastnasite, on the other hand, is a fluorocarbonate associated with igneous intrusions in quartzite or epithermal, fluorite-bearing veins, and is mined by open-pit methods. The ore is beneficiated by flotation, then acid-leached, filtered and calcined to produce a rare earth concentrate. Although a light rare earth, samarium oxide is isolated only after about three stages of solvent extraction, together with heavier oxides of gadolinium, terbium, and yttrium.

  3. Implementation of Ultrasonic Sensing for High Resolution Measurement of Binary Gas Mixture Fractions

    PubMed Central

    Bates, Richard; Battistin, Michele; Berry, Stephane; Bitadze, Alexander; Bonneau, Pierre; Bousson, Nicolas; Boyd, George; Bozza, Gennaro; Crespo-Lopez, Olivier; Riva, Enrico Da; Degeorge, Cyril; Deterre, Cecile; DiGirolamo, Beniamino; Doubek, Martin; Favre, Gilles; Godlewski, Jan; Hallewell, Gregory; Hasib, Ahmed; Katunin, Sergey; Langevin, Nicolas; Lombard, Didier; Mathieu, Michel; McMahon, Stephen; Nagai, Koichi; Pearson, Benjamin; Robinson, David; Rossi, Cecilia; Rozanov, Alexandre; Strauss, Michael; Vitek, Michal; Vacek, Vaclav; Zwalinski, Lukasz

    2014-01-01

    We describe an ultrasonic instrument for continuous real-time analysis of the fractional mixture of a binary gas system. The instrument is particularly well suited to measurement of leaks of a high molecular weight gas into a system that is nominally composed of a single gas. Sensitivity < 5 × 10−5 is demonstrated to leaks of octaflouropropane (C3F8) coolant into nitrogen during a long duration (18 month) continuous study. The sensitivity of the described measurement system is shown to depend on the difference in molecular masses of the two gases in the mixture. The impact of temperature and pressure variances on the accuracy of the measurement is analysed. Practical considerations for the implementation and deployment of long term, in situ ultrasonic leak detection systems are also described. Although development of the described systems was motivated by the requirements of an evaporative fluorocarbon cooling system, the instrument is applicable to the detection of leaks of many other gases and to processes requiring continuous knowledge of particular binary gas mixture fractions. PMID:24961217

  4. Quantum cascade laser based monitoring of CF{sub 2} radical concentration as a diagnostic tool of dielectric etching plasma processes

    SciTech Connect

    Hübner, M.; Lang, N.; Röpcke, J.; Helden, J. H. van; Zimmermann, S.; Schulz, S. E.; Buchholtz, W.

    2015-01-19

    Dielectric etching plasma processes for modern interlevel dielectrics become more and more complex by the introduction of new ultra low-k dielectrics. One challenge is the minimization of sidewall damage, while etching ultra low-k porous SiCOH by fluorocarbon plasmas. The optimization of this process requires a deeper understanding of the concentration of the CF{sub 2} radical, which acts as precursor in the polymerization of the etch sample surfaces. In an industrial dielectric etching plasma reactor, the CF{sub 2} radical was measured in situ using a continuous wave quantum cascade laser (cw-QCL) around 1106.2 cm{sup −1}. We measured Doppler-resolved ro-vibrational absorption lines and determined absolute densities using transitions in the ν{sub 3} fundamental band of CF{sub 2} with the aid of an improved simulation of the line strengths. We found that the CF{sub 2} radical concentration during the etching plasma process directly correlates to the layer structure of the etched wafer. Hence, this correlation can serve as a diagnostic tool of dielectric etching plasma processes. Applying QCL based absorption spectroscopy opens up the way for advanced process monitoring and etching controlling in semiconductor manufacturing.

  5. Fluorine-rich planetary environments as possible habitats for life.

    PubMed

    Budisa, Nediljko; Kubyshkin, Vladimir; Schulze-Makuch, Dirk

    2014-01-01

    In polar aprotic organic solvents, fluorine might be an element of choice for life that uses selected fluorinated building blocks as monomers of choice for self-assembling of its catalytic polymers. Organofluorine compounds are extremely rare in the chemistry of life as we know it. Biomolecules, when fluorinated such as peptides or proteins, exhibit a "fluorous effect", i.e., they are fluorophilic (neither hydrophilic nor lipophilic). Such polymers, capable of creating self-sorting assemblies, resist denaturation by organic solvents by exclusion of fluorocarbon side chains from the organic phase. Fluorous cores consist of a compact interior, which is shielded from the surrounding solvent. Thus, we can anticipate that fluorine-containing "teflon"-like or "non-sticking" building blocks might be monomers of choice for the synthesis of organized polymeric structures in fluorine-rich planetary environments. Although no fluorine-rich planetary environment is known, theoretical considerations might help us to define chemistries that might support life in such environments. For example, one scenario is that all molecular oxygen may be used up by oxidation reactions on a planetary surface and fluorine gas could be released from F-rich magma later in the history of a planetary body to result in a fluorine-rich planetary environment. PMID:25370378

  6. Open cycle heat pump development for local resource use. Phase 2: District heating case study analysis

    NASA Astrophysics Data System (ADS)

    Patch, K. D.; Dibella, F. A.; Glick, J. F.; Becker, F. E.

    1990-04-01

    District heating (DH) systems provide thermal energy to their customers in the form of hot water or steam. These systems can use one or more types of heat sources to meet the thermal load, including boilers, cogeneration systems, or low-grade heat sources in conjunction with a heat pump. Most large-scale heat pumps operate using the closed-cycle concept and usually use a chlorinated fluorocarbon (CFC) as the working fluid. An alternative to this approach is the quasi open-cycle heat pump, which was first studied in a Phase 1 report entitled, Open-Cycle Heat Pump Development for Local Resource Use, DOE/CE/26563-5. The quasi open-cycle (QOC) heat pump actually uses the district heating transport medium as its working fluid. This document is the Final Report prepared as a part of Task 6 of Open-Cycle Heat Pump Development for Local Resource Use, Phase 2 District Heating Case Study Analysis. The objective of this study contract was to assess the application of the QOC heat pump in an actual case study.

  7. Fluorescence-Based Bacterial Overlay Method for Simultaneous In Situ Quantification of Surface-Attached Bacteria▿

    PubMed Central

    Müller, Rainer; Gröger, Gerhard; Hiller, Karl-Anton; Schmalz, Gottfried; Ruhl, Stefan

    2007-01-01

    For quantification of bacterial adherence to biomaterial surfaces or to other surfaces prone to biofouling, there is a need for methods that allow a comparative analysis of small material specimens. A new method for quantification of surface-attached biotinylated bacteria was established by in situ detection with fluorescence-labeled avidin-D. This method was evaluated utilizing a silicon wafer model system to monitor the influences of surface wettability and roughness on bacterial adhesion. Furthermore, the effects of protein preadsorption from serum, saliva, human serum albumin, and fibronectin were investigated. Streptococcus gordonii, Streptococcus mitis, and Staphylococcus aureus were chosen as model organisms because of their differing adhesion properties and their clinical relevance. To verify the results obtained by this new technique, scanning electron microscopy and agar replica plating were employed. Oxidized and poly(ethylene glycol)-modified silicon wafers were found to be more resistant to bacterial adhesion than wafers coated with hydrocarbon and fluorocarbon moieties. Roughening of the chemically modified surfaces resulted in an overall increase in bacterial attachment. Preadsorption of proteins affected bacterial adherence but did not fully abolish the influence of the original surface chemistry. However, in certain instances, mostly with saliva or serum, masking of the underlying surface chemistry became evident. The new bacterial overlay method allowed a reliable quantification of surface-attached bacteria and could hence be employed for measuring bacterial adherence on material specimens in a variety of applications. PMID:17308176

  8. One-step fabrication of nickel nanocones by electrodeposition using CaCl2·2H2O as capping reagent

    NASA Astrophysics Data System (ADS)

    Lee, Jae Min; Jung, Kyung Kuk; Lee, Sung Ho; Ko, Jong Soo

    2016-04-01

    In this research, a method for the fabrication of nickel nanocones through the addition of CaCl2·2H2O to an electrodeposition solution was proposed. When electrodeposition was performed after CaCl2·2H2O addition, precipitation of the Ni ions onto the (2 0 0) crystal face was suppressed and anisotropic growth of the nickel electrodeposited structures was promoted. Sharper nanocones were produced with increasing concentration of CaCl2·2H2O added to the solution. Moreover, when temperature of the electrodeposition solutions approached 60 °C, the apex angle of the nanostructures decreased. In addition, the nanocones produced were applied to superhydrophobic surface modification using a plasma-polymerized fluorocarbon (PPFC) coating. When the solution temperature was maintained at 60 °C and the concentration of the added CaCl2·2H2O was 1.2 M or higher, the fabricated samples showed superhydrophobic surface properties. The proposed nickel nanocone formation method can be applied to various industrial fields that require metal nanocones, including superhydrophobic surface modification.

  9. Liquid ventilation in dogs: an apparatus for normobaric and hyperbaric studies.

    PubMed

    Harris, D J; Coggin, R R; Roby, J; Feezor, M; Turner, G; Bennett, P B

    1983-04-01

    A liquid-breathing apparatus is described for remote surface studies and for use in experiments of near-hydraulic compression in dogs. It consists of a flexible tank sealed against chamber gas, containing a supply of clean warmed (38 degrees C) fluorocarbon (FC-80) equilibrated with 1 bar O2 and an electronically controlled means of delivering the liquid to the dog. Each breath (tidal volume 290 ml) was "weighed" into the animal by the signal from a force platform supporting the dog and a digital control unit that automatically actuated inspired-and expired-line solenoid valves. The apparatus was successfully used to remotely maintain liquid ventilation in awake dogs for 2 h during surface studies (5 dogs) and in dives to 1,000 m seawater (5 dogs). During liquid breathing, mean arterial O2 partial pressure was always adequate (congruent to 300 Torr) and mean arterial CO2 partial pressure was normal (less than or equal to 40 Torr). An uncompensated metabolic acidosis was indicated by low pH values and a decrease in arterial base excess to--4.5 meq x 1(-1). O2 uptake and CO2 output appeared to be significantly lower (42 and 35%, respectively) during liquid ventilation. PMID:6222021

  10. Application of Si and SiO2 Etching Mechanisms in CF4/C4F8/Ar Inductively Coupled Plasmas for Nanoscale Patterns.

    PubMed

    Lee, Junmyung; Efremov, Alexander; Yeom, Geun Young; Lim, Nomin; Kwon, Kwang-Ho

    2015-10-01

    An investigation of the etching characteristics and mechanism for both Si and SiO2 in CF4/C4F8/Ar inductively coupled plasmas under a constant gas pressure (4 mTorr), total gas flow rate (40 sccm), input power (800 W), and bias power (150 W) was performed. It was found that the variations in the CF4/C4F8 mixing ratio in the range of 0-50% at a constant Ar fraction of 50% resulted in slightly non-monotonic Si and SiO2 etching rates in CF4-rich plasmas and greatly decreasing etching rates in C4F8-rich plasmas. The zero-dimensional plasma model, Langmuir probe diagnostics, and optical emission spectroscopy provided information regarding the formation-decay kinetics for the plasma active species, along with their densities and fluxes. The model-based analysis of the etching kinetics indicated that the non-monotonic etching rates were caused not by the similar behavior of the fluorine atom density but rather by the opposite changes of the fluorine atom flux and ion energy flux. It was also determined that the great decrease in both the Si and SiO2 etching rates during the transition from the CF4/Ar to C4F8/Ar gas system was due to the deposition of the fluorocarbon polymer film. PMID:26726514

  11. Surface roughening of ground fused silica processed by atmospheric inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Xin, Qiang; Li, Na; Wang, Jun; Wang, Bo; Li, Guo; Ding, Fei; Jin, Huiliang

    2015-06-01

    Subsurface damage (SSD) is a defect that is inevitably induced during mechanical processes, such as grinding and polishing. This defect dramatically reduces the mechanical strength and the laser damage thresholds of optical elements. Compared with traditional mechanical machining, atmospheric pressure plasma processing (APPP) is a relatively novel technology that induces almost no SSD during the processing of silica-based optical materials. In this paper, a form of APPP, inductively coupled plasma (ICP), is used to process fused silica substrates with fluorocarbon precursor under atmospheric pressure. The surface morphology evolution of ICP-processed substrates was observed and characterized by confocal laser scanning microscope (CLSM), field emission scanning electron microscope (SEM), and atomic force microscopy (AFM). The results show that the roughness evolves with the etching depth, and the roughness evolution is a single-peaked curve. This curve results from the opening and the coalescing of surface cracks and fractures. The coalescence procedure of these microstructures was simulated with two common etched pits on a polished fused silica surface. Understanding the roughness evolution of plasma-processed surface might be helpful in optimizing the optical fabrication chain that contains APPP.

  12. Possible greenhouse effects of tetrafluoromethane and carbon dioxide emitted from aluminum production

    NASA Astrophysics Data System (ADS)

    Weston, Ralph E.

    Tetrafluoromethane (CF 4) is an extremely stable gas which strongly absorbs infrared radiation at 8 ?m, and therefore is capable of influencing the greenhouse effect. No natural sources have been identified, and the major anthropogenic source appears to be the electrolytic smelting of alumina to produce aluminum. Measurements of CF 4 concentrations in the atmosphere are reviewed, and these are combined with aluminum production rates to provide an estimate of 1.3-3.6 kg of CF 4 emitted per ton of aluminum produced for the period up to 1985. Aluminum production also requires large amounts of electrical energy, leading to the emission of as much as 22 tons of carbon dioxide per ton of aluminum due to fossil fuel combustion in power plants. The present day contribution of hydroelectric power reduces this figure to about 14 tons of carbon dioxide per ton of aluminum. An estimate of the relative radiative trapping of CF 4 and CO 2 emitted in aluminum production during this same period (1900-1985) indicates that the effect of CF 4 is about one-third that of the CO 2 formed by aluminum production. However, the emission of fluorocarbons from modem aluminum electrolysis cells is much lower than previous estimates indicate, and this factor is considered in estimating potential long-term global warming effects of CF 4 and CO 2 from aluminum production. Possible processes leading to removal of CF 4 from the atmosphere are described.

  13. Optical manipulation of nanocontainers for biotechnology

    NASA Astrophysics Data System (ADS)

    Helmerson, Kristian; Reiner, Joseph E.; Edgu-Fry, Erge; Wells, Jeffrey; Kishore, Rani; Locascio, Laurie; Gilson, Michael

    2004-10-01

    We are developing optically based techniques for the manipulation of nano-containers (containers with sub-picoliter volumes) for handling chemicals in order to perform ultra-small volume chemistry. We are currently investigating three systems, liposomes, polymersomes and hydrosomes, for use as nano-containers. Liposomes and polymersomes are closed structures composed of a lipid and polymer membrane, respectively, that acts as a barrier to separate an aqueous interior environment from an aqueous exterior environment. We are typically working with liposomes or polymersomes that are approximately 10 μm in diameter. Hydrosomes are micron-sized, surfactant-stabilized water droplets that reside in a fluorocarbon environment. The optical techniques we are using include optical tweezers, for trapping and remotely moving the nano-containers, and an "optical scalpel" for localized disruption of lipid and polymer membranes in order to induce fusion of liposomes and polymersomes. In all three systems, we are able to bring together two similar nano-container using optical trapping and subsequently fuse them together, which allows their contents to mix. With the liposomes and hydrosomes we have been able to demonstrate their use for performing a controlled, elementary chemical reaction.

  14. New concepts for refrigerant leak detection and mixture measurement

    NASA Astrophysics Data System (ADS)

    Chen, F. C.; Allman, S. L.; Chen, C. H.

    Since the discovery that chlorofluorocarbons (CFC's) destroy the ozone layer, the need to reduce the release of these refrigerants into the environment has become critical. A total ban of ozone-depleting CFC's is expected within a few years, and hydrofluorocarbons (HFC's) and fluorocarbons (FC's) and their mixtures are expected to be used during a transition period. Several HFC and FC refrigerants are currently being considered as CFC substitutes. The electronic refrigerant leak detectors currently being considered as CFC substitutes. The electronic refrigerant leak detectors currently on the market were developed to detect CFC's and are not as sensitive to HFC's. Although incremental improvement can be made to these devices to detect HFC's, they often lead to increased false signals. Also, there is no simple device available to measure the composition of a refrigerant mixture. The authors present two new concepts to aid in the development of two portable instruments that can be used for HFC leak detection and for quantitative measurement of refrigerant mixture compositions. The development of simple, easy-to-use portable leak detectors and refrigerant mixture meters is essential to the wide use of alternative refrigerants in industry.

  15. Correlation of refrigerant mass flow rate through adiabatic capillary tubes using mixture refrigerant carbondioxide and ethane for low temperature applications

    NASA Astrophysics Data System (ADS)

    Nasruddin, Syaka, Darwin R. B.; Alhamid, M. Idrus

    2012-06-01

    Various binary mixtures of carbon dioxide and hydrocarbons, especially propane or ethane, as alternative natural refrigerants to Chlorofluorocarbons (CFCs) or Hydro fluorocarbons (HFCs) are presented in this paper. Their environmental performance is friendly, with an ozone depletion potential (ODP) of zero and Global-warming potential (GWP) smaller than 20. The capillary tube performance for the alternative refrigerant HFC HCand mixed refrigerants have been widely studied. However, studies that discuss the performance of the capillary tube to a mixture of natural refrigerants, in particular a mixture of azeotrope carbon dioxide and ethane is still undeveloped. A method of empirical correlation to determine the mass flow rate and pipe length has an important role in the design of the capillary tube for industrial refrigeration. Based on the variables that effect the rate of mass flow of refrigerant in the capillary tube, the Buckingham Pi theorem formulated eight non-dimensional parameters to be developed into an empirical equations correlation. Furthermore, non-linear regression analysis used to determine the co-efficiency and exponent of this empirical correlation based on experimental verification of the results database.

  16. Two-dimensional tracer transport: Derivation of residual mean circulation and eddy transport tensor from a 3-D model data set

    NASA Astrophysics Data System (ADS)

    Pitari, Giovanni; Visconti, Guido

    1985-08-01

    Two-dimensional distributions for long-lived species, N2O, CFCl3, and CF2Cl2, have been calculated by using a 2-D model extending from the ground to 70 km. The model utilizes a residual mean meridional circulation and a set of eddy diffusion coefficients. Both these fields have been obtained from the output of the MIT-GIT three-dimensional general circulation model of the stratosphere. The calculation of the residual mean circulation takes into account consistent fields of temperature and diabatic heating, meridional temperature advection, and vertical eddy fluxes. The diffusion tensor is obtained following Holton (1981) and utilizes the eddy field that is an output of the 3-D model. The chemical source term is treated by introducing an additional tensor, following the suggestion by Tung (1982). This approach has the advantage of using the same matrix for all the chemical compounds. Values obtained for the residual mean meridional mass flux are in good agreement with similar results. The trace gas distributions obtained show a fairly good agreement in the equatorial regions but overpredict the concentration in the mid-latitude stratosphere. This is a common modeling problem, especially with fluorocarbons, and is attributed, in our case, to values of the Kyy and Kzz components that are too large in the lower stratosphere. This particular result is probably due to the heating parameterization adopted in the original general circulation model.

  17. Mixtures of hydrogenated and fluorinated lactobionamide surfactants with cationic surfactants: study of hydrogenated and fluorinated chains miscibility through potentiometric techniques.

    PubMed

    Peyre, Véronique; Patil, Sandeep; Durand, Grégory; Pucci, Bernard

    2007-11-01

    The work reported herein deals with the aqueous behavior of hydrocarbon and/or fluorocarbon ionic and nonionic surfactants mixtures. These mixtures were studied using potentiometric techniques in NaBr (0.1 mol L-1) aqueous solution as well as in pure water. Mixed micelles were formed from a cationic surfactant (dodecyl or tetradecyltrimethylammonium bromide respectively called DTABr or TTABr) and neutral lactobionamide surfactants bearing a hydrogenated dodecyl chain (H12Lac) or a fluorinated chain (CF3-(CF2)5-(CH2)2- or CF3-(CF2)7-(CH2)2-). We showed that concentrations of ionic and nonionic surfactants in the monomeric form as well as the composition of the mixed micelles can be specified thanks to a potentiometric technique. The complete characterization does not request any model of micellization a priori. The activities of the micellar phase constituents, as well as the free enthalpies of mixing, were calculated. The subsequent interpretation only relies on the experimental characterization. Comparison of the behaviors of the various systems with a model derived from the regular solution theory reveals the predominant part of electrostatic interactions in the micellization phenomenon. It also appears that the energy of interaction between hydrogenated and fluorinated chains is unfavorable to mixing and is of much lower magnitude than the electric charges interactions. PMID:17935362

  18. Etching radical controlled gas chopped deep reactive ion etching

    DOEpatents

    Olynick, Deidre; Rangelow, Ivo; Chao, Weilun

    2013-10-01

    A method for silicon micromachining techniques based on high aspect ratio reactive ion etching with gas chopping has been developed capable of producing essentially scallop-free, smooth, sidewall surfaces. The method uses precisely controlled, alternated (or chopped) gas flow of the etching and deposition gas precursors to produce a controllable sidewall passivation capable of high anisotropy. The dynamic control of sidewall passivation is achieved by carefully controlling fluorine radical presence with moderator gasses, such as CH.sub.4 and controlling the passivation rate and stoichiometry using a CF.sub.2 source. In this manner, sidewall polymer deposition thicknesses are very well controlled, reducing sidewall ripples to very small levels. By combining inductively coupled plasmas with controlled fluorocarbon chemistry, good control of vertical structures with very low sidewall roughness may be produced. Results show silicon features with an aspect ratio of 20:1 for 10 nm features with applicability to nano-applications in the sub-50 nm regime. By comparison, previous traditional gas chopping techniques have produced rippled or scalloped sidewalls in a range of 50 to 100 nm roughness.

  19. Solvent and substrate effects on inkjet-printed dots and lines of silver nanoparticle colloids

    NASA Astrophysics Data System (ADS)

    Shin, Kwon-Yong; Lee, Sang-Ho; Oh, Je Hoon

    2011-04-01

    The shape changes of inkjet-printed dots and lines were investigated by varying the primary solvent of nanosilver colloids, surface wettability and substrate temperature. The morphological changes in dots and lines in array patterns due to the interaction between neighboring dots or lines during evaporation was also examined for two different nanosilver colloids. In order to examine the effect of solvent evaporation rate, two different solvents with different boiling points (BP) were employed for nanosilver inks. With a fluorocarbon film coating and subsequent ultraviolet ozone (UV/O3) treatment, various surface wettability conditions were obtained on silicon (Si) wafers. Substrate temperature was varied from room temperature to 80 °C, and droplets from a 50 µm diameter nozzle were printed onto the substrate after optimizing the ejection of individual droplets. The results indicate that the shapes and sizes of dots and lines are sensitive to changes in both surface energy and substrate temperature, and the ink with a higher BP solvent produces larger dots under the same surface condition due to its slower evaporation. Dots and lines with better quality are achieved using the ink with a lower BP solvent. The morphological changes in dot and line arrays are dependent on the evaporation rate of the primary solvent as well as the distance between neighboring features. As a result, selecting a proper solvent for nanosilver ink is very crucial for controlling the shape and morphology of inkjet-printed patterns.

  20. Molecular modeling of the morphology and transport properties of two direct methanol fuel cell membranes: phenylated sulfonated poly(ether ether ketone ketone) versus Nafion

    SciTech Connect

    Devanathan, Ramaswami; Idupulapati, Nagesh B.; Dupuis, Michel

    2012-08-14

    We have used molecular dynamics simulations to examine membrane morphology and the transport of water, methanol and hydronium in phenylated sulfonated poly ether ether ketone ketone (Ph-SPEEKK) and Nafion membranes at 360 K for a range of hydration levels. At comparable hydration levels, the pore diameter is smaller, the sulfonate groups are more closely packed, the hydronium ions are more strongly bound to sulfonate groups, and the diffusion of water and hydronium is slower in Ph-SPEEKK relative to the corresponding properties in Nafion. The aromatic carbon backbone of Ph-SPEEKK is less hydrophobic than the fluorocarbon backbone of Nafion. Water network percolation occurs at a hydration level ({lambda}) of {approx}8 H{sub 2}O/SO{sub 3}{sup -}. At {lambda} = 20, water, methanol and hydronium diffusion coefficients were 1.4 x 10{sup -5}, 0.6 x 10{sup -5} and 0.2 x 10{sup -5} cm{sup 2}/s, respectively. The pore network in Ph-SPEEKK evolves dynamically and develops wide pores for {lambda} > 20, which leads to a jump in methanol crossover and ion transport. This study demonstrates the potential of aromatic membranes as low-cost challengers to Nafion for direct methanol fuel cell applications and the need to develop innovative strategies to combat methanol crossover at high hydration levels.

  1. Design and analysis of a 5-MW vertical-fluted-tube condenser for geothermal applications

    SciTech Connect

    Llewellyn, G.H.

    1982-03-01

    The design and analysis of an industtial-sized vertical-fluted-tube condenser. The condenser is used to condense superheated isobutane vapor discharged from a power turbine in a geothermal test facility operated for the US Department of Energy. The 5-MW condenser has 1150 coolant tubes in a four-pass configuration with a total heat transfer area of 725 m/sup 2/ (7800 ft/sup 2/). The unit is being tested at the Geothermal Components Test Facility in the Imperial Valley of East Mesa, California. The condenser design is based on previous experimental research work done at the Oak Ridge National Laboratory on condensing refrigerants on a wide variety of single vertical tubes. Condensing film coefficients obtained on the high-performance vertical fluted tubes in condensing refrigerants are as much as seven times greater than those obtained with vertical smooth tubes that have the same diameter and length. The overall heat transfer performance expected from the fluted tube condenser is four to five times the heat transfer obtained from the identical units employing smooth tubes. Fluted tube condensers also have other direct applications in the Ocean Thermal Energy Conversion (OTEC) program in condensing ammonia, in the petroleum industry in condensing light hydrocarbons, and in the air conditioning and refrigeration industry in condensing fluorocarbon vapors.

  2. Analysis and interpretation of the performance degradation of glass Resistive Plate Chambers operated in streamer mode

    NASA Astrophysics Data System (ADS)

    Calcaterra, A.; de Sangro, R.; Patteri, P.; Piccolo, M.; Della Mea, G.; Restello, S.; Ferri, F.; Musella, P.; Redaelli, N.; Tabarelli de Fatis, T.; Tinti, G.; Mannocchi, G.; Trinchero, G.

    2007-10-01

    The long-term stability of Resistive Plate Chambers (RPCs) with glass electrodes was studied for one year with a dedicated test station hosting about 10 m2 of detectors. RPCs were operated in streamer mode with a ternary gas mixture containing argon (27%), isobutane (9%) and tetrafluoroethane (64%). Environmental conditions were kept under control and, in particular, the water pollution in the gas, deemed responsible for the degradation of glass RPC performance, was monitored never to exceed 30 ppm in the exhaust line. Evidence for a substantial aging of the detectors was observed, resulting in a loss of efficiency correlated to an increased rate of spurious streamers. This can be ascribed to the chemical attack of the glass surface by hydrofluoric acid formed in the streamer process, as confirmed by detailed morphological and chemical analyses of the electrode surface. Our results strengthen the indication that the instability of glass RPCs in the long term is related to the use of fluorocarbons as quenching medium and is not due to external pollutants.

  3. Effect of plasma treatments on the steam-sour gas resistance and lubricity of elastomers. [Rubbers used: copoly(ethene-propene); copoly(1,1-difluoroethane-hexafluoropropene); copoly(2-propenenitrile-1,3 butadiene); plasma polymerized tetrafluoroethane

    SciTech Connect

    Arnold, C. Jr.; Bieg, K.W.; Cuthrell, R.E.; Nelson, G.C.

    1982-03-01

    Elastomers are widely used in drilling and logging applications as static seals such as casing packers and dynamic seals such as o-rings for drill bits. Static seals often fail in service because of thermochemical degradation due to the combined effects of steam and sour gas at elevated temperatures that are characteristic of deep wells. Dynamic seals frequently fail because of abrasive wear that occurs even at the low temperatures that prevail in shallow wells. We have shown that improved steam-sour gas resistance of a fully formulated ethylene-propylene rubber at elevated temperatures can be achieved by coating the rubber with a thin film of plasma polymerized tetrafluoroethylene. Thus, no change in the mechanical properties of the coated rubber was observed after exposure to steam and sour gas at 275/sup 0/C for 48 h. In contrast, the shear modulus of the upcoated rubber increased by 96% after the same exposure. While the effectiveness of the fluorocarbon coating decreased at longer exposure times, short-term protection of elastomers could be beneficial in certain logging operations. It was also found that the coefficient of friction of a nitrile rubber (Buna N) was reduced by 20% after treatment with a carbon tetrafluoride plasma. This enhanced lubricity could lead to better wear characteristics in conventional drill bits where the seal is in contact with a moving metal surface. The surfaces of the plasma treated elastomers were characterized by water contact angle, scanning electron microscopy, and electron spectroscopy for chemical analysis.

  4. Modification of TiO₂ electrode with organic silane interposed layer for high-performance of dye-sensitized solar cells.

    PubMed

    Sewvandi, Galhenage A; Tao, Zhuoqi; Kusunose, Takafumi; Tanaka, Yasuhiro; Nakanishi, Shunsuke; Feng, Qi

    2014-04-23

    Back electron transfer from the TiO2 electrode surface to the electrolyte is the main reason behind the low-open circuit potential (Voc) and the low-fill factor (FF) of the dye-sensitized solar cells (DSSCs). Modifications to the TiO2 electrode, fabricated using {010}-faceted TiO2 nanoparticles with six different kinds of silane, are reported to decrease the back electron transfer on the TiO2 surface. The effect of alkyl chain length of hydrocarbon silanes and fluorocarbon silanes on adsorption parameters of surface coverage and adsorption constant, interfacial resistance, and photovoltaic performances were investigated. Adsorption isotherms, impedance analysis, and photovoltaic measurements were used as the investigation techniques. The reduction of back electron transfer depended on the TiO2 surface coverage by silane, alkyl chain length, and the molecular structure of the silane. Even though Voc and FF were improved, significant reduction in short-circuit photocurrent density (Jsc) was observed after silanization because of desorption of dye during silanization. A new approach, sequential adsorption process of silane and dye, was introduced to enhance Voc and FF without lowering Jsc. Heptadecafluorodecyl trimethoxy-silane showed the highest coverage on the surface of the TiO2 and had the highest effect on the performance improvement of the DSSC, where Voc, FF, and efficiency (η) were improved by 22, 8.0, and 22%, respectively. PMID:24684283

  5. Langmuir Probe Measurements in an Inductively Coupled Ar/CF4 Plasmas

    NASA Technical Reports Server (NTRS)

    Rao, M. V. V. S.; Meyyappan, M.; Sharma, S. P.; Arnold, James O. (Technical Monitor)

    2000-01-01

    Technological advancement in the microelectronics industry requires an understanding of the physical and chemical processes occurring in plasmas of fluorocarbon gases, such as carbon tetrafluoride (CF4) which is commonly used as an etchant, and their mixtures to optimize various operating parameters. In this paper we report data on electron number density (ne), electron temperature'(Te), electron energy distribution function (EEDF), mean electron energy, ion number density (ni), and plasma potential (Vp) measured by using Langmuir probe in an inductively coupled 13.56 MHz radio frequency plasmas generated in 50%Ar:50%CF4 mixture in the GEC cell. The probe data were recorded at various radial positions providing radial profiles of these plasma parameters at 10-50 mTorr pressures and 200 W and 300 W of RF power. Present measurements indicate that the electron and ion number densities increase with increase in pressure and power. Whereas the plasma potential and electron temperature decrease with increase in pressure, and they weakly depend on RF power. The radial profiles exhibit that the electron and ion number densities and the plasma potential peak at the center of the plasma with an exponential fall away from it, while the electron temperature has a minimum at the center and it increases steadily towards the electrode edge. The EEDFs have a characteristic drop near the low energy end at all pressures and pressures and their shapes represent non-Maxwellian plasma and exhibit more like Druyvesteyn energy distribution.v

  6. In situ CF3 Detection in Low Pressure Inductive Discharges by Fourier Transform Infrared Spectroscopy

    NASA Technical Reports Server (NTRS)

    Kim, J. S.; Cappelli, M. A.; Sharma, S. P.; Arnold, J. O. (Technical Monitor)

    1998-01-01

    The detection of CF(x) (x=1-3) radicals in low pressure discharges using source gases such as CF4 and CHF3 is of importance to the understanding of their chemical structure and relevance in plasma based etching processes. These radicals are known to contribute to the formation of fluorocarbon polymer films, which affect the selectivity and anisotropy of etching. In this study, we present preliminary results of the quantitative measurement of trifluoromethyl radicals, CF3, in low pressure discharges. The discharge studied here is an inductively (transformer) coupled plasma (ICP) source in the GEC reference cell, operating on pure CF4 at pressures ranging from 10 - 100 mTorr, This plasma source generates higher electron number densities at lower operating pressures than obtainable with the parallel-plate capacitively coupled version of the GEC reference cell. Also, this expanded operating regime is more relevant to new generations of industrial plasma reactors being used by the microelectronics industry. Fourier transform infrared (FTIR) spectroscopy is employed to observe the absorption band of CF3 radicals in the electronic ground state X2Al in the region of 1233-1270/cm. The spectrometer is equipped with a high sensitivity HgCdTe (MCT) detector and has a fixed resolution of 0.125/cm. The CF3 concentrations are measured for a range of operating pressures and discharge power levels.

  7. Mixed waste chemical compatibility with packaging components

    SciTech Connect

    Nigrey, P.J.; Conroy, M.; Blalock, L.B.

    1994-05-01

    In this paper, a chemical compatibility testing program for packaging of mixed wastes at will be described. We will discuss the choice of four y-radiation doses, four time durations, four temperatures and four waste solutions to simulate the hazardous waste components of mixed wastes for testing materials compatibility of polymers. The selected simulant wastes are (1) an aqueous alkaline mixture of sodium nitrate and sodium nitrite; (2) a chlorinated hydrocarbon mixture; (3) a simulant liquid scintillation fluid; and (4) a mixture of ketones. A selection of 10 polymers with anticipated high resistance to one or more of these types of environments are proposed for testing as potential liner or seal materials. These polymers are butadiene acrylonitrile copolymer, cross-linked polyethylene, epichlorhyarin, ethylene-propylene rubber, fluorocarbon, glass-filled tetrafluoroethylene, high-density poly-ethylene, isobutylene-isoprene copolymer, polypropylene, and styrene-butadiene rubber. We will describe the elements of the testing plan along with a metric for establishing time resistance of the packaging materials to radiation and chemicals.

  8. The evolution of spatial ordering of oil drops fast spreading on a water surface

    PubMed Central

    Yamamoto, Daigo; Nakajima, Chika; Shioi, Akihisa; Krafft, Marie Pierre; Yoshikawa, Kenichi

    2015-01-01

    The design of dynamically self-assembled systems is of high interest in science and technology. Here, we report a unique cascade in the self-ordering of droplets accompanied by a dewetting transition. The dynamic self-emergent droplets are observed when a thin liquid layer of an immiscible fluorocarbon oil (perfluorooctyl bromide, PFOB) is placed on a water surface. Due to the gradual evaporation of PFOB, a circular PFOB-free domain appears as a result of a local dewetting transition. A circular pearling structure is generated at the rim with the growth of the dewetting hole. As the next stage, linear arrays of droplets are generated in a radial manner from the centre of the hole. These one-dimensional arrangements then evolve into two-dimensional hexagonal arrays of microdroplets through collective rhythmical shrinking/expanding motions. The emergence of such dynamic patterns is discussed in terms of the nonlinear kinetics of the dewetting transition under thermodynamically dissipative conditions. PMID:25998157

  9. Detecting onset of chain scission and crosslinking of γ-ray irradiated elastomer surfaces using frictional force microscopy

    NASA Astrophysics Data System (ADS)

    Banerjee, S.; Sinha, N. K.; Gayathri, N.; Ponraju, D.; Dash, S.; Tyagi, A. K.; Raj, Baldev

    2007-02-01

    We report here that atomic force microscopy (AFM) in frictional force mode can be used to detect the onset of chain scission and crosslinking in polymeric and macromolecular samples upon irradiation. A systematic investigation to detect chain scission and crosslinking of two elastomers, (1) ethylene-propylene-diene monomer rubber and (2) fluorocarbon rubber, upon γ-ray irradiation has been carried out using frictional force microscopy (FFM). From the AFM results we observed that both the elastomers show a systematic smoothening of its surfaces, as the γ-ray dose rate increases. However, the frictional property studied using FFM of the sample surfaces show an initial increase and then a decrease as a function of dose rate. This behaviour of increase in its frictional property has been attributed to the onset of chain scission, and the subsequent decrease in friction has been attributed to the onset of crosslinking of the polymer chains. The evaluated qualitative and semi-quantitative changes observed in the overall frictional property as a function of the γ-ray dose rate for the two elastomers are presented in this paper.

  10. Uncertainties in Air Exchange using Continuous-Injection, Long-Term Sampling Tracer-Gas Methods

    SciTech Connect

    Sherman, Max H.; Walker, Iain S.; Lunden, Melissa M.

    2013-12-01

    The PerFluorocarbon Tracer (PFT) method is a low-cost approach commonly used for measuring air exchange in buildings using tracer gases. It is a specific application of the more general Continuous-Injection, Long-Term Sampling (CILTS) method. The technique is widely used but there has been little work on understanding the uncertainties (both precision and bias) associated with its use, particularly given that it is typically deployed by untrained or lightly trained people to minimize experimental costs. In this article we will conduct a first-principles error analysis to estimate the uncertainties and then compare that analysis to CILTS measurements that were over-sampled, through the use of multiple tracers and emitter and sampler distribution patterns, in three houses. We find that the CILTS method can have an overall uncertainty of 10-15percent in ideal circumstances, but that even in highly controlled field experiments done by trained experimenters expected uncertainties are about 20percent. In addition, there are many field conditions (such as open windows) where CILTS is not likely to provide any quantitative data. Even avoiding the worst situations of assumption violations CILTS should be considered as having a something like a ?factor of two? uncertainty for the broad field trials that it is typically used in. We provide guidance on how to deploy CILTS and design the experiment to minimize uncertainties.

  11. Slippery liquid-infused porous surfaces showing marine antibiofouling properties.

    PubMed

    Xiao, Linlin; Li, Junsheng; Mieszkin, Sophie; Di Fino, Alessio; Clare, Anthony S; Callow, Maureen E; Callow, James A; Grunze, Michael; Rosenhahn, Axel; Levkin, Pavel A

    2013-10-23

    Marine biofouling is a longstanding problem because of the constant challenges placed by various fouling species and increasingly restricted environmental regulations for antifouling coatings. Novel nonbiocidal strategies to control biofouling will necessitate a multifunctional approach to coating design. Here we show that slippery liquid-infused porous surfaces (SLIPSs) provide another possible strategy to obtaining promising antifouling coatings. Microporous butyl methacrylate-ethylene dimethacrylate (BMA-EDMA) surfaces are prepared via UV-initiated free-radical polymerization. Subsequent infusion of fluorocarbon lubricants (Krytox103, Krytox100, and Fluorinert FC-70) into the porous microtexture results in liquid-repellent slippery surfaces. To study the interaction with marine fouling organisms, settlement of zoospores of the alga Ulva linza and cypris larvae of the barnacle Balanus amphitrite is tested in laboratory assays. BMA-EDMA surfaces infused with Krytox103 and Krytox100 exhibit remarkable inhibition of settlement (attachment) of both spores and cyprids to a level comparable to that of a poly(ethylene glycol) (PEG)-terminated self-assembled monolayer. In addition, the adhesion strength of sporelings (young plants) of U. linza is reduced for BMA-EDMA surfaces infused with Krytox103 and Krytox100 compared to pristine (noninfused) BMA-EDMA and BMA-EDMA infused with Fluorinert FC-70. Immersion tests suggest a correlation between the stability of slippery coatings in artificial seawater and fouling resistance efficacy. The results indicate great potential for the application of this concept in fouling-resistant marine coatings. PMID:24067279

  12. Simultaneous measurement of pressure in the interstitium and the terminal lymphatics of the cat mesentery.

    PubMed Central

    Clough, G; Smaje, L H

    1978-01-01

    1. Simultaneous measurements of the pressure in terminal lymphatics and interstitial tissue have been made in the exteriorized cat mesentery superfused with either physiological salt solution (Krebs solution) or a water-immiscible fluorocarbon, FC-80. 2. The pressures within individual terminal lymphatics were measured using glass micropipettes attached to a servo pressure-measuring system. Tissue pressures were recorded using saline-filled cotton-wool wicks. 3. Mean pressure recorded in the terminal lymphatics of the Krebs-superfused mesentery were slightly above atmospheric (+0.2 mmHg, n = 45), while those recorded in the FC-80-superfused mesentery were slightly below atmospheric (-0.2 mmHg, n = 46). 4. Tissue pressures were also slightly subatmospheric in the in situ mesentery, and the recently exposed tissue. Continuous superfusion with Krebs solution caused the tissue pressure to rise to atmospheric pressure or above; with FC-80-superfusion the tissue pressure also rose, but never to above atmospheric pressure. 5. Isolated strips of mesentery immersed in Krebs solutions of different concentrations gained weight, but when immersed in FC-80 no change in weight was detected. 6. It was concluded that the interstitial gel of the mesentery is normally unsaturated and that superfusion with Krebs solution leads to tissue oedema. This tendency is less marked in FC-80-superfused preparations. Possible mechanisms for lymph formation and propulsion are discussed. Images Fig. 1 PMID:722586

  13. Ab Initio Study of Hydration and Proton Dissociation in Ionomer Membranes

    SciTech Connect

    Idupulapati, Nagesh B.; Devanathan, Ramaswami; Dupuis, Michel

    2010-07-01

    We present a comparative study of proton dissociation in various functional acidic units that are promising candidates as building blocks for polymeric electrolyte membranes. Minimum energy structures for four acidic moieties with clusters of 1-6 water molecules were determined using density functional theory at the B3LYP/6-311G** level starting from chemically rational initial configurations. The perfluoro sulfonyl imide acid group (CF3CF2SO2NHSO2CF3) was observed to be the strongest acid, due to the substantial electron withdrawing effect of both fluorocarbon groups. The hydrophilic functional group (CH3OC6H3OCH3C6H4SO3H) of sulfonated polyetherether ketone (SPEEK) membrane was found to be the strongest base with the acidic proton dissociation requiring the addition of six water molecules and the hydrated proton being more tightly bound to the conjugate base. Even though both perfluoro sulfonyl imides and sulfonic acids (hydrophilic functional groups for sulfonyl imide and Nafion ionomers respectively) required only three water molecules to exhibit spontaneous proton dissociation, the largest possible solvent-separated hydronium ion was attained only for the sulfonyl imide moiety. These results provide a scientific basis for understanding the improved conductivity of perfluorinated sulfonyl imide-based membranes relative to that of the widely-used Nafion membrane.

  14. Stationary nanoliter droplet array with a substrate of choice for single adherent/nonadherent cell incubation and analysis

    PubMed Central

    Shemesh, Jonathan; Ben Arye, Tom; Avesar, Jonathan; Kang, Joo H.; Fine, Amir; Super, Michael; Meller, Amit; Ingber, Donald E.; Levenberg, Shulamit

    2014-01-01

    Microfluidic water-in-oil droplets that serve as separate, chemically isolated compartments can be applied for single-cell analysis; however, to investigate encapsulated cells effectively over prolonged time periods, an array of droplets must remain stationary on a versatile substrate for optimal cell compatibility. We present here a platform of unique geometry and substrate versatility that generates a stationary nanodroplet array by using wells branching off a main microfluidic channel. These droplets are confined by multiple sides of a nanowell and are in direct contact with a biocompatible substrate of choice. The device is operated by a unique and reversed loading procedure that eliminates the need for fine pressure control or external tubing. Fluorocarbon oil isolates the droplets and provides soluble oxygen for the cells. By using this approach, the metabolic activity of single adherent cells was monitored continuously over time, and the concentration of viable pathogens in blood-derived samples was determined directly by measuring the number of colony-formed droplets. The method is simple to operate, requires a few microliters of reagent volume, is portable, is reusable, and allows for cell retrieval. This technology may be particularly useful for multiplexed assays for which prolonged and simultaneous visual inspection of many isolated single adherent or nonadherent cells is required. PMID:25053808

  15. Triboelectricity: macroscopic charge patterns formed by self-arraying ions on polymer surfaces.

    PubMed

    Burgo, Thiago A L; Ducati, Telma R D; Francisco, Kelly R; Clinckspoor, Karl J; Galembeck, Fernando; Galembeck, Sergio E

    2012-05-15

    Tribocharged polymers display macroscopically patterned positive and negative domains, verifying the fractal geometry of electrostatic mosaics previously detected by electric probe microscopy. Excess charge on contacting polyethylene (PE) and polytetrafluoroethylene (PTFE) follows the triboelectric series but with one caveat: net charge is the arithmetic sum of patterned positive and negative charges, as opposed to the usual assumption of uniform but opposite signal charging on each surface. Extraction with n-hexane preferentially removes positive charges from PTFE, while 1,1-difluoroethane and ethanol largely remove both positive and negative charges. Using suitable analytical techniques (electron energy-loss spectral imaging, infrared microspectrophotometry and carbonization/colorimetry) and theoretical calculations, the positive species were identified as hydrocarbocations and the negative species were identified as fluorocarbanions. A comprehensive model is presented for PTFE tribocharging with PE: mechanochemical chain homolytic rupture is followed by electron transfer from hydrocarbon free radicals to the more electronegative fluorocarbon radicals. Polymer ions self-assemble according to Flory-Huggins theory, thus forming the experimentally observed macroscopic patterns. These results show that tribocharging can only be understood by considering the complex chemical events triggered by mechanical action, coupled to well-established physicochemical concepts. Patterned polymers can be cut and mounted to make macroscopic electrets and multipoles. PMID:22530971

  16. Mechanisms of oxygen plasma nanotexturing of organic polymer surfaces: from stable super hydrophilic to super hydrophobic surfaces.

    PubMed

    Tsougeni, K; Vourdas, N; Tserepi, A; Gogolides, E; Cardinaud, C

    2009-10-01

    Plasma processing is used to fabricate super hydrophilic or super hydrophobic polymeric surfaces by means of O2 plasma etching of two organic polymers, namely, poly(methyl methacrylate) (PMMA) and poly(ether ether ketone) (PEEK); a C4F8 plasma deposition follows O2 plasma etching, if surface hydrophobization is desired. We demonstrate high aspect ratio pillars with height ranging from 16 nm to several micrometers depending on the processing time, and contact angle (CA) close to 0 degrees after O2-plasma treatment or CA of 153 degrees (with CA hysteresis lower than 5 degrees) after fluorocarbon deposition. Super hydrophobic surfaces are robust and stable in time; in addition, aging of super hydrophilic surfaces is significantly retarded because of the beneficial effect of the nanotextured topography. The mechanisms responsible for the plasma-induced PMMA and PEEK surface nanotexturing are unveiled through intelligent experiments involving intentional modification of the reactor wall material and X-ray photoelectron spectroscopy, which is also used to study the surface chemical modification in the plasma. We prove that control of plasma nanotexture can be achieved by carefully choosing the reactor wall material. PMID:19788226

  17. Nanotextured super-hydrophobic transparent poly(methyl methacrylate) surfaces using high-density plasma processing

    NASA Astrophysics Data System (ADS)

    Vourdas, Nikolaos; Tserepi, Angeliki; Gogolides, Evangelos

    2007-03-01

    We present an environmentally friendly, rapid, no-rinse and mass-production amenable plasma process for the fabrication of super-hydrophobic (SH) poly(methyl methacrylate) (PMMA) surfaces using only a one load/unload step in a low-pressure, high-density plasma reactor. First, oxygen plasma is applied to nanotexture the PMMA surface via etching processes leading to high aspect ratio (HAR) topography, with dual-roughness characteristics for short process durations, as evidenced by AFM analysis. The duration of the process may range from 1 min to several min depending on the roughness amplitude and on the degree of transparency desired. The significance of the ion-bombardment is revealed and discussed. After this first step, the gas chemistry is changed to a fluorocarbon one which leads to a few nanometres-thick Teflon-like film deposition, thus altering the PMMA surface chemistry within a few seconds. Following this process, a very large area (depending on the reactor scale) of the PMMA may become SH in less than 1.5 min (total process duration) with a transparency as desired (from fully transparent to milky and antireflective). The contact angles (CA) measured are approximately 152° with 5° hysteresis. For short process durations, the dual-roughness character of PMMA surfaces favours the SH formation, despite the low roughness factor. Furthermore, the dry and low-temperature character of the process ensures the intactness of PMMA's shape and bulk mechanical properties.

  18. Precise control of critical dimension shrinkage and enlargement by in-situ polysilicon etch

    NASA Astrophysics Data System (ADS)

    Linliu, Kung; Kuo, Mai-Rue

    2000-07-01

    The control of critical dimension shrinkage and enlargement of polysilicon line or space obtained precisely using in- situ process with different ratio of gas combination is investigate din this paper. A polysilicon line could be etched down to 0.054 micrometers from 0.22 micrometers of the original critical dimension (CD). The CD shrinking rate of polysilicon line is 2.48 nm per second per side. On the other hand, the space can also be trimmed down to 0.03 micrometers from the original CD of 0.3 micrometers . The CD enlarging rate of polysilicon rate is 0.421 nm per second per side using the present polymer deposition method. The factors that cause shrinkage and enlargement of CD are the etching of photoresist and the deposition of polymer on the surface of photoresist, respectively. The oxygen-rich gas is used for the shrinkage of CD and the fluorocarbon-rich gas is used for the enlargement of CD. Therefore, a critical dimension could not afforded by the present existed optical photolithography tool or method might probably be solved by alternative innovation such as the plasma dry etching technology.

  19. Application of high-speed digital holographic interferometry for the analysis of temperature distributions and velocity fields in subcooled flow boiling

    NASA Astrophysics Data System (ADS)

    Bloch, Gregor; Kuczaty, Julian; Sattelmayer, Thomas

    2014-02-01

    Holographic interferometry can be used to visualize density fields in fluids, and thus give insight into temperature distributions in flows. A fully digital reconstruction technique for holographic interferograms is presented that allows to create high-speed interferometric recordings and gives time-resolved information about heat transfer processes. The technique can also be used for a sequential (image to image) analysis of the recordings, which offers higher sensitivity and fewer errors due to optical impurities. Experiments are conducted with a vertical flow boiling channel with one heated wall, using a low boiling fluorocarbon as working liquid in regimes of steady-state nucleate boiling at critical heat flux (CHF), steady-state film boiling and CHF transient. Recording frequencies are up to 7,000 fps. The technique is used to analyze boiling processes at different fluid subcoolings with and without added turbulence. The results give enhanced insight into the temperature distributions, effects of different flow inserts and mechanisms of heat transfer in flow boiling at high heat fluxes. Furthermore, a velocimetric application of the technique is presented using cross-correlation for tracing of density gradients both in boiling and unheated flows. This application gives insight to the velocity distributions in the liquid surrounding the vapor layer. The results show good comparison to particle image velocimetry measurements for the same setup.

  20. Calculation of Electron-Impact Ionization Cross Sections of Molecules Using the DM Formalism

    NASA Astrophysics Data System (ADS)

    Deutsch, H.; Becker, K.; Maerk, T. D.

    1999-10-01

    Much emphasis has been devoted recently to the experimental determination of absolute electron-impact ionization cross sections of molecules and radicals due to the importance of these cross sections in many applications. Supporting calculations have been lagging to some extent. Due to the complexity of such calculations simplistic additivity rules and semi-empirical methods have often been used. More rigorous methods, i.e. methods that incorporate some quantum mechanically calculated quantities include the BEB formalism of Kim and co- workers, the method of Khare and collaborators, and the semi-classical Deutsch -Maerk (DM)-formalism. We report results of a comprehensive comparison of calculated ionization cross sections for molecules and radicals using the DM-formalism with available experimental data and with available BEB calculations and results from the application of the model of Khare and co- workers. Targets include hydrocarbon and fluorocarbon compounds, radicals and simple di-, tri-, and polyatomic species. *Work supported by OEW-EURATOM Assoc., FWF, OENB, BMWV, and the US DOE.