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1

Pentafluorotellurium Oxide Fluorocarbons.  

National Technical Information Service (NTIS)

In accordance with this invention, a novel class of high density fluids based on TeF50-substituted fluorocarbons and a process for their synthesis have been discovered. The synthesis utilizes oxypentafluortellurium hypohalites as reactants to effect an ad...

C. J. Schack

1983-01-01

2

21 CFR 177.1380 - Fluorocarbon resins.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Fluorocarbon resins. 177.1380 Section 177.1380 Food and Drugs...Food Contact Surfaces § 177.1380 Fluorocarbon resins. Fluorocarbon resins may be safely used as articles or components...

2011-04-01

3

21 CFR 177.1380 - Fluorocarbon resins.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2009-04-01 true Fluorocarbon resins. 177.1380 Section 177.1380 Food and Drugs...Food Contact Surfaces § 177.1380 Fluorocarbon resins. Fluorocarbon resins may be safely used as articles or components...

2010-01-01

4

21 CFR 177.1380 - Fluorocarbon resins.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Fluorocarbon resins. 177.1380 Section 177.1380 Food and Drugs...Food Contact Surfaces § 177.1380 Fluorocarbon resins. Fluorocarbon resins may be safely used as articles or components...

2012-04-01

5

water-soluble fluorocarbon coating  

NASA Technical Reports Server (NTRS)

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.

Nanelli, P.

1979-01-01

6

Metals plated on fluorocarbon polymers  

NASA Technical Reports Server (NTRS)

Electroplating lead on fluorocarbon polymer parts is accomplished by etching the parts to be plated with sodium, followed by successive depositions of silver and lead from ultrasonically agitated plating solutions. Metals other than lead may be electroplated on the silvered parts.

Ford, H.; Krasinsky, J. B.; Vango, S. P.

1964-01-01

7

Molecular origins of fluorocarbon hydrophobicity  

PubMed Central

We have undertaken atomistic molecular simulations to systematically determine the structural contributions to the hydrophobicity of fluorinated solutes and surfaces compared to the corresponding hydrocarbon, yielding a unified explanation for these phenomena. We have transformed a short chain alkane, n-octane, to n-perfluorooctane in stages. The free-energy changes and the entropic components calculated for each transformation stage yield considerable insight into the relevant physics. To evaluate the effect of a surface, we have also conducted contact-angle simulations of water on self-assembled monolayers of hydrocarbon and fluorocarbon thiols. Our results, which are consistent with experimental observations, indicate that the hydrophobicity of the fluorocarbon, whether the interaction with water is as solute or as surface, is due to its “fatness.” In solution, the extra work of cavity formation to accommodate a fluorocarbon, compared to a hydrocarbon, is not offset by enhanced energetic interactions with water. The enhanced hydrophobicity of fluorinated surfaces arises because fluorocarbons pack less densely on surfaces leading to poorer van der Waals interactions with water. We find that interaction of water with a hydrophobic solute/surface is primarily a function of van der Waals interactions and is substantially independent of electrostatic interactions. This independence is primarily due to the strong tendency of water at room temperature to maintain its hydrogen bonding network structure at an interface lacking hydrophilic sites.

Dalvi, Vishwanath H.; Rossky, Peter J.

2010-01-01

8

Fluorocarbon Solid Propellant with Burning Rate Modifier.  

National Technical Information Service (NTIS)

This invention pertains to solid fluorocarbon propellant compositions containing burning rate modifiers which have high structural integrity and a long storage life under varying environmental conditions.

J. B. Eldridge E. C. Julian R. L. Dow G. B. Rice

1975-01-01

9

Fluorocarbon-enhanced mutagenesis of polyaromatic hydrocarbons  

SciTech Connect

The widely used fluorocarbon refrigerant and cleaning solvent 1,1,2-trichloro-1,2,2-trifluoroethane (Freon TF), though generally considered biologically inert, enhances the metabolic activation of chemical carcinogens. Liver microsomal extracts from mice given single intraperitoneal injections of this fluorocarbon showed significant increases in their ability to activate carcinogenic polyaromatic hydrocarbons to form mutagens, compared to control mice injected with saline. Polyaromatic hydrocarbons aminofluorene and acetylaminofluorene were activated in this way. Mutagenicity was measured by a microbial assay. Both commercial grade and redistilled fluorocarbons gave similar results, that is, more highly active liver extracts after administration of the fluorocarbon preparation to mice. Neither industrial grade nor redistilled preparation was itself mutagenic. A combined liver microsomal extract from mice breathing Freon TF at 20,000 ppm in air for 8 hr also had enhanced ability to activate aminofluorene as a mutagen. Exposing mice to Freon TF by inhalation more closely matches the normal route of human exposure to fluorocarbons. The results of this study imply that low-molecular-weight fluorocarbons may pose a carcinogenic risk by acting as cocarcinogenic enhancers of carcinogen activation. The possibility that fluorocarbons are cocarcinogens in this way has apparently not been heretofore considered.

Mahurin, R.G.; Bernstein, R.L.

1988-02-01

10

Functionally terminated liquid nitroso fluorocarbon terpolymers  

NASA Technical Reports Server (NTRS)

Properties of polymer for conformal coating for electronic circuitry are described. Nitroso fluorocarbon polymers were selected for application. Chemical reactions for production of polymers are discussed. Technique allows regulation of crosslink densities, molecular weight, and viscosity.

Mayes, N.; Marcellis, A.

1972-01-01

11

Lubrication and Physical Properties of Fluorocarbon Fluids.  

National Technical Information Service (NTIS)

Nine fluorocarbon fluids representing four classes of fluorinated organic liquids were compared with the base fluids for the present specification weapons lubricants. Wear, friction, load-carrying capacity, and physical property data show that several of ...

G. P. Murphy C. J. Quilty

1969-01-01

12

Vapor pressures of new fluorocarbons  

SciTech Connect

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%.

Kubota, H.; Yamashita, T.; Tanaka, Y.; Makita, T. (Kobe Univ. (Japan))

1989-05-01

13

Structure Modification of Fluorocarbon Ether Bibenzoxazole Polymers to Improve Hydrolytic Stability.  

National Technical Information Service (NTIS)

Hydrolytically and thermooxidatively stable fluorocarbon ether bibenzoxazole (FEB) polymers were synthesized by the acetic acid-promoted polycyclocondensation of fluorocarbon ether bis (o-aminophenol) monomers with novel fluorocarbon ether dithioimidate e...

R. C. Evers G. J. Moore J. L. Burkett

1979-01-01

14

Fluorocarbons and fluorinated amphiphiles in drug delivery and biomedical research  

Microsoft Academic Search

The specific properties of fluorocarbons, exceptional chemical and biological inertness, high gas-dissolving capacity, low surface tension, excellent spreading characteristics and high fluidity, have triggered numerous applications of these compounds in oxygen delivery. An injectable emulsion of fluorocarbon-in-water destined to deliver oxygen to tissues at risk of hypoxia has now completed Phase III clinical trials in Europe. A neat fluorocarbon is

Marie Pierre Krafft

2001-01-01

15

Gas Embolism Due to Intravenous FC 80 Liquid Fluorocarbon.  

National Technical Information Service (NTIS)

Lethal gas embolism always occurs after FC 80 liquid fluorocarbon is injected intravenously (0.1 ml/kg body mass) in dogs breathing room air but not in dogs breathing oxygenated FC 80 liquid fluorocarbon. Gas embolism is not prevented in dogs that have be...

D. J. Sass R. A. Van Dyke E. H. Wood S. A. Johnson P. Didisheim

1974-01-01

16

Piezoelectric activity and thermal stability of cellular fluorocarbon films  

NASA Astrophysics Data System (ADS)

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.

Zhang, Xiaoqing; Huang, Jinfeng; Xia, Zhongfu

2007-12-01

17

Fluoro-Carbonate Solvents for Li-Ion Cells.  

National Technical Information Service (NTIS)

A number of fluoro-carbonate solvents were evaluated as electrolytes for Li-ion cells. These solvents are fluorine analogs of the conventional electrolyte solvents such as dimethyl carbonate, ethylene carbonate, diethyl carbonate in Li-ion cells. Conducti...

Nagasubramanian

1999-01-01

18

Decontamination by cleaning with fluorocarbon surfactant solutions  

SciTech Connect

In the nuclear industry, facilities and their components inevitably become contaminated with radioactive materials. This report documents the application of a novel particle-removal process developed by Entropic Systems, Inc. (ESI), to decontaminate critical instruments and parts that are contaminated with small radioactive particles that adhere to equipment surfaces. The tests were performed as a cooperative effort between ESI and the Chemical Technology Division of the Oak Ridge National Laboratory (ORNL). ESI developed a new, environmentally compatible process to remove small particles from solid surfaces that is more effective than spraying or sonicating with CFC-113. This process uses inert perfluorinated liquids as working media; the liquids have zero ozone-depleting potential, are nontoxic and nonflammnable, and are generally recognized as nonhazardous materials. In the ESI process, parts to be cleaned are first sprayed or sonicated with a dilute solution of a high-molecular-weight fluorocarbon surfactant in an inert perfluorinated liquid to effect particle removal. The parts are then rinsed with the perfluorinated liquid to remove the fluorocarbon surfactant applied in the first step, and the residual rinse liquid is then evaporated from the parts into an air or nitrogen stream from which it is recovered. Nuclear contamination is inherently a surface phenomenon. The presence of radioactive particles is responsible for all ``smearable`` contamination and, if the radioactive particles are small enough, for some of the fixed contamination. Because radioactivity does not influence the physical chemistry of particle adhesion, the ESI process should be just as effective in removing radioactive particles as it is in removing nonradioactive particles.

Kaiser, R. [Entropic Systems, Inc., Winchester, MA (United States); Benson, C.E.; Meyers, E.S. [Oak Ridge National Lab., TN (United States); Vaughen, V.C.A. [Chemical Engineering and Safety Consulting Services, Knoxville, TN (United States)

1994-02-01

19

Fluorinated diamond particles bonded in a filled fluorocarbon resin matrix  

DOEpatents

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.

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

1983-11-14

20

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

NASA Technical Reports Server (NTRS)

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.

Talcott, N. A., Jr.

1977-01-01

21

Fluorocarbon seal replaces metal piston ring in low density gas environment  

NASA Technical Reports Server (NTRS)

Reinforced fluorocarbon cupseal, which provides an integral lip-type seal, replaces the metal piston rings in piston-cylinder configurations used in the compression of low density gases. The fluorocarbon seal may be used as cryogenic compressor piston seals.

Morath, W. D.; Morgan, N. E.

1967-01-01

22

PART I. FLUOROCARBON FLAMES. PART II. DISSOLUTION OF URANIUM IN NITRIC ACID  

Microsoft Academic Search

The phenomenon of fluorocarbon flames was investigated by: (1) ; attempting to produce flames by the reaction of several fluorocarbons with ; oxygen, chlorine, nitrogen dioxide, nitric oxide, and various mixtures of these ; gases in a flow system, and (2) obtaining thc spectra of the flames thus produced. ; The fluorocarbons investigated were chlorotrifluoroethylene, 1, 1-; difluoroethylene, 1,2-dichloro1,2-difluoroethylene, perfluorocyclobutene,

Salzman

1962-01-01

23

Recovery of fluorocarbons in Japan as a measure for abating global warming  

Microsoft Academic Search

The objective of this study is to evaluate the potential for recovering fluorocarbons as measures for the abatement of global warming. In this study, we focused on the three different kinds of fluorocarbons: CFCs, HCFCs and HFCs, and targeted refrigerant use because of the availability of relevant data. We first estimated future fluorocarbon emissions from the targeted appliances; we next

Tatsuya Hanaoka; Hisashi Ishitani; Ryuji Matsuhashi; Yoshikuni Yoshida

2002-01-01

24

Effect of fluorocarbons on acetylcholinesterase activity and some counter measures  

NASA Technical Reports Server (NTRS)

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.

Young, W.; Parker, J. A.

1975-01-01

25

Mass and energy spectroscopy of fluorocarbon plasmas.  

NASA Astrophysics Data System (ADS)

It is helpful for many processing plasmas which are operated using fluorocarbon and similar gases to have available information on the nature of the ions generated in the plasma and on the energies with which they impact on surfaces exposed to the plasma. To illustrate the range of data which may be obtained using a Hiden mass/energy spectrometer attached to a plasma reactor, measurements for RF plasmas in CF4 CF3I, CCl2F2, and CHClF2 in a parallel-plate reactor are outlined. Of particular interest, are the data obtained for the production of negative ions. For the experiments carried out with a 10 Watt plasma in CHClF2, the dominant negative ions were H^-, Cl^- and F^- . For each of these species, the relative rates of production from the parent gas and the mixture of neutral fragments produced by dissociation in the plasma were determined for electron energies of between 0.5 and 30eV. In the presence of a plasma, the contributions to the negative ion population of electron attachment to the dissociation fragments are also clearly seen. In the absence of a plasma, the electron attachment rates measured for the production of CF3^- ions from the parent CF4 ,show clearly the contributions of two formation pathways via the ground and excited states of the temporary CF4^- ions first formed in the electron/molecule collisions. The ability of the mass/energy analyser to observe the energies of the attachment products is helpful.

Rees, J. A.

2008-10-01

26

Method and means for producing fluorocarbon finishes on fibrous structures  

NASA Technical Reports Server (NTRS)

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.

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

1981-01-01

27

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

SciTech Connect

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.

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

2005-02-01

28

Biocompatible surfactants for water-in-fluorocarbon emulsions.  

PubMed

Drops of water-in-fluorocarbon emulsions have great potential for compartmentalizing both in vitro and in vivo biological systems; however, surfactants to stabilize such emulsions are scarce. Here we present a novel class of fluorosurfactants that we synthesize by coupling oligomeric perfluorinated polyethers (PFPE) with polyethyleneglycol (PEG). We demonstrate that these block copolymer surfactants stabilize water-in-fluorocarbon oil emulsions during all necessary steps of a drop-based experiment including drop formation, incubation, and reinjection into a second microfluidic device. Furthermore, we show that aqueous drops stabilized with these surfactants can be used for in vitro translation (IVT), as well as encapsulation and incubation of single cells. The compatability of this emulsion system with both biological systems and polydimethylsiloxane (PDMS) microfluidic devices makes these surfactants ideal for a broad range of high-throughput, drop-based applications. PMID:18813384

Holtze, C; Rowat, A C; Agresti, J J; Hutchison, J B; Angilè, F E; Schmitz, C H J; Köster, S; Duan, H; Humphry, K J; Scanga, R A; Johnson, J S; Pisignano, D; Weitz, D A

2008-10-01

29

Spraylon fluorocarbon encapsulation for silicon solar cell arrays  

NASA Technical Reports Server (NTRS)

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.

1977-01-01

30

Highly exothermic and superhydrophobic mg/fluorocarbon core/shell nanoenergetic arrays.  

PubMed

Mg/fluorocarbon core/shell nanoenergetic arrays are prepared onto silicon substrate, with Mg nanorods as the core and fluorocarbon as the shell. Mg nanorods are deposited by the glancing angle deposition technique, and the fluorocarbon layer is then prepared as a shell to encase the Mg nanorods by the magnetron sputtering deposition process. Scanning electron microscopy and transmission electron microscopy show the core/shell structure of the Mg/fluorocarbon arrays. X-ray energy-dispersive spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy are used to characterize the structural composition of the Mg/fluorocarbon. It is found that the as-prepared fluorocarbon layer consists of shorter molecular chains compared to that of bulk polytetrafluoroethylene, which is proven beneficial to the low onset reaction temperature of Mg/fluorocarbon. Water contact angle test demonstrates the superhydrophobicity of the Mg/fluorocarbon arrays, and a static contact angle as high as 162° is achieved. Thermal analysis shows that the Mg/fluorocarbon material exhibits a very low onset reaction temperature of about 270 °C as well as an ultrahigh heat of reaction approaching 9 kJ/g. A preliminary combustion test reveals rapid combustion wave propagation, and a convective mechanism is adopted to explain the combustion behaviors. PMID:24918872

Zhou, Xiang; Xu, Daguo; Yang, Guangcheng; Zhang, Qiaobao; Shen, Jinpeng; Lu, Jian; Zhang, Kaili

2014-07-01

31

Release and fate of fluorocarbons in a shredder residue landfill cell: 2. Field investigations  

Microsoft Academic Search

The shredder residues from automobiles, home appliances and other metal containing products are often disposed in landfills, as recycling technologies for these materials are not common in many countries. Shredder waste contains rigid and soft foams from cushions and insulation panels blown with fluorocarbons. The objective of this study was to determine the gas composition, attenuation, and emission of fluorocarbons

Charlotte Scheutz; Anders M. Fredenslund; Jonas Nedenskov; Peter Kjeldsen

2010-01-01

32

Spraylon fluorocarbon encapsulation for silicon solar cell arrays, phase 3  

NASA Technical Reports Server (NTRS)

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.

Naes, L. G.

1978-01-01

33

Marine biofouling on the fluorocarbon coatings comprising PTFE powders  

NASA Astrophysics Data System (ADS)

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.

Zhang, Zhan-Ping; Qi, Yu-Hong; Liu, Hong; Zhang, Zheng

2009-07-01

34

Health effects among refrigeration repair workers exposed to fluorocarbons.  

PubMed Central

Refrigeration repair workers may be intermittently exposed to fluorocarbons and their thermal decomposition products. A case of peripheral neuropathy (distal axonopathy) in a commercial refrigeration repairman prompted an epidemiological investigation of the health of refrigeration repair workers. No additional cases of peripheral neuropathy were identified among the 27 refrigeration repair workers studied. A reference group of 14 non-refrigeration repair workers was also studied. No differences were noted between groups for the ulnar (motor and sensory), median (motor and sensory), peroneal, sural, or tibial nerve conduction velocities. Refrigeration repair workers reported palpitations and lightheadedness significantly more often than workers in the reference group. No clinical neurological or electroneurophysiological abnormalities were detected in eight refrigeration repair workers followed up for three years during continuous employment.

Campbell, D D; Lockey, J E; Petajan, J; Gunter, B J; Rom, W N

1986-01-01

35

Tantalum etching in fluorocarbon/oxygen rf glow discharges  

SciTech Connect

Etch rates of tantalum in tetrafluoromethane-oxygen and hexafluoroethane-oxygen rf glow discharges were measured {ital in} {ital situ} as functions of pressure, reactor residence time, temperature, and applied plasma power. A dramatic increase in the etch rate was observed as the pressure increased. In addition, two distinct temperature regimes occurred in Arrhenius plots. Such data suggest strong effects due to heat of reaction in the Ta/CF{sub 4}-O{sub 2} etch system. The observed etch-rate pressure dependence can be explained by assuming first-order kinetics for the reaction of fluorine atoms with tantalum. Evidence for etch-rate quenching at high pressures due to an increase in the deposition of an inhibiting fluorocarbon surface layer is presented.

Martz, J.C.; Hess, D.W. (Department of Chemical Engineering, 201 Gilman Hall, University of California, Berkeley, California 94720 (USA)); Anderson, W.E. (Materials Science, MS E549, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (USA) Technology Division, MS E549, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (USA))

1990-04-15

36

Effect of Hydrocarbon Fill Fluids on 5109S Neoprene and QXA 3770 Fluorocarbon Rubbers.  

National Technical Information Service (NTIS)

The chemical resistance of two elastomers, 5109S neoprene rubber and QXA 3770 fluorocarbon rubber, to three hydrocarbon-based buoyancy fluids has been assessed by monitoring weight gain and dimensional changes of rubber samples immersed in the fluids. The...

J. A. Hiltz I. A. Keough

1998-01-01

37

Selective Plasma Deposition of Fluorocarbon Films on SAMs  

NASA Technical Reports Server (NTRS)

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.

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

2006-01-01

38

Investigation of the low-pressure plasma-chemical conversion of fluorocarbon waste gases  

Microsoft Academic Search

The kinetics of the plasma-chemical conversion of a number of saturated, as well as of unsaturated, fluorocarbon compounds\\u000a is studied in an oxygen-based rf discharge by FTIR spectroscopy. Unsaturated fluorocarbons are rapidly converted into CF4 and C2F6, which, in the presence of silica walls, are finally converted quantitatively into SiF4 (etch reaction). The results of this investigation are used to

F. W. Breitbarth; D. Berg; K. Dumke; H.-J. Tiller

1997-01-01

39

Wettability and thermal stability of fluorocarbon films deposited by deep reactive ion etching  

SciTech Connect

Fluorocarbon films have low surface energy and can be used as antistiction coating for microelectromechanical systems. By using the passivation process in a deep reactive ion etcher, the fluorocarbon films can be deposited and integrated with other processes in the clean room. The properties such as wettability, surface energies, and thermal stability, have been investigated in detail. It has been found that the fluorocarbon films deposited have a static water contact angle of 109 deg. and a surface energy around 14.5 mJ/m{sup 2}, whereas as-received and as-deposited single silicon, poly silicon, and silicon nitride have a much lower water contact angle and a higher surface energy. The fluorocarbon films keep their good hydrophobicity up to 300 deg. C, and the degradation temperature depends on the thickness of the fluorocarbon films. Decomposition happens at lower temperatures (100-300 deg. C) even though the decomposition rate is quite slow without affecting the contact angle. The decomposition mechanism at low temperatures (less than 300 deg. C) might be different from that at high temperatures. It has been shown that the fluorocarbon film deposited by a deep reactive ion etcher tool provides very high hydrophobicity, low surface energy, good thermal stability, and antiadhesion behavior for use in nanoimprinting lithography.

Zhuang Yanxin; Menon, Aric [MIC, Department of Micro and Nanotechnology, Technical University of Denmark, Building 345 east, DK-2800, Kgs. Lyngby (Denmark)

2005-05-01

40

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

NASA Astrophysics Data System (ADS)

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.

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

2014-01-01

41

A molecular dynamics investigation of fluorocarbon based layer-by-layer etching of silicon and SiO2  

Microsoft Academic Search

A molecular dynamics model is used to understand the layer-by-layer etching of Si and SiO2 using fluorocarbon and Ar+ ions. In these two-step etch processes, a nanometer-scale fluorocarbon passivation layer is grown on the material's surface using low energy CFx+ ions or radicals. The top layers of the material are then reactive ion etched by Ar+ ions utilizing the fluorocarbon

S. Rauf; T. Sparks; P. L. G. Ventzek; V. V. Smirnov; A. V. Stengach; K. G. Gaynullin; V. A. Pavlovsky

2007-01-01

42

Frictional properties of mixed fluorocarbon/hydrocarbon silane monolayers: a simulation study.  

PubMed

Because of small surface area to volume ratios nanoscale devices can exhibit dominant surface forces that can quickly degrade unlubricated contacting surfaces. While fluorinated materials have been widely used as lubricants, because of their low critical surface tension and high thermal and mechanical stability, fluorinated monolayer coatings, which are suitable for lubricating nanoscale devices, are less effective as lubricants. Although fluorinated monolayers are more stable than their hydrocarbon counterparts against elevated temperature and humidity, they are known to exhibit higher frictional forces. To overcome this issue, here we study mixed monolayers composed of both hydrocarbon and fluorocarbon chains. Hydrocarbon-based monolayers have been widely studied and shown to improve frictional properties and device life. To investigate the frictional behavior of mixed fluorocarbon/hydrocarbon monolayers, molecular dynamics simulations of pure hydrogenated and fluorinated chains and mixed fluorinated/hydrogenated chains on silica surfaces have been performed. The adhesion and friction between the nanoconfined monolayers as a function of normal load, chain length, and chemical composition of the monolayer coating have been investigated, and mixed fluorocarbon/hydrocarbon monolayers found to outperform both pure fluorocarbon and pure hydrocarbon monolayers. Surface coverage was found to have a significant effect on the performance of all systems studied with higher surface coverage resulting in lower frictional forces. The simulations also show that when the hydrocarbon chains in the monolayer are longer than the fluorocarbon chains, a liquidlike layer is formed by the longer hydrocarbon chains that protrudes above the shorter fluorocarbon chains and aids in friction reduction. A frictional load dependence is also seen in these mixed monolayer systems because of repulsive interactions between the fluorocarbon base layer and the hydrocarbon liquidlike layer. A chain length difference of eight carbons between the base layer and the liquidlike layer was found to provide the lowest friction, while both a larger (because of increased entanglement) and a smaller (insufficient atoms between the contacting base layers to form a liquidlike layer) chain length difference increased friction. PMID:22937771

Lewis, J Ben; Vilt, Steven G; Rivera, Jose L; Jennings, G Kane; McCabe, Clare

2012-10-01

43

Roughening of porous SiCOH materials in fluorocarbon plasmas  

NASA Astrophysics Data System (ADS)

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.

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

2010-07-01

44

Highly stable hysteresis-free carbon nanotube thin-film transistors by fluorocarbon polymer encapsulation.  

PubMed

We report hysteresis-free carbon nanotube thin-film transistors (CNT-TFTs) employing a fluorocarbon polymer (Teflon-AF) as an encapsulation layer. Such fluorocarbon encapsulation improves device uniformity with excellent operation stability in air and even in water. The fluoropolymers possess high hydrophobicity for efficient removal of water molecules from the vicinity of nanotubes, which are known to induce charge trapping. In addition, the strong dipole associated with the carbon-fluorine bonds can provide effective screening of the charge carriers in nanotubes from various trap states in the substrate. We also report on the extended applications of encapsulation with Teflon-AF for the realization of dual-gate CNT-TFTs, where one gate is used to control the threshold voltage and the other to switch the device. The fluorocarbon encapsulation technique presents a promising approach for enhanced device reliability, which is critical for future system-level electronics based on CNTs. PMID:24796606

Ha, Tae-Jun; Kiriya, Daisuke; Chen, Kevin; Javey, Ali

2014-06-11

45

Synthesis and tuning of bimodal mesoporous silica by combined hydrocarbon/fluorocarbon surfactant templating.  

PubMed

Hydrocarbon and fluorocarbon surfactants show highly nonideal mixing that under some conditions results in demixing of the two types of surfactants into distinct populations of fluorocarbon-rich and hydrocarbon-rich aggregates. This also occurs in materials prepared by cooperative assembly of hydrolyzed tetraethoxysilane with mixtures of cetyltrimethylammonium chloride (CTAC) and 1,1,2,2-tetrahydro-perfluorodecylpyridinium chloride (HFDePC). Here, we report conditions under which demixed micelles lead to bimodal mesoporous materials (including specific concentrations of ammonia and salt in the synthesis solution) and show that the sizes of the hydrocarbon-templated and fluorocarbon-templated pores can be finely and independently controlled by adding lipophilic or fluorophilic oils, respectively. Nitrogen sorption isotherms and transmission electron microscopy provide clear evidence for a single phase of demixed but disordered wormhole-like pores. PMID:19323503

Xing, Rong; Lehmler, Hans-Joachim; Knutson, Barbara L; Rankin, Stephen E

2009-06-01

46

Novel fluoro-carbon functional monomer for dental bonding.  

PubMed

Among several functional monomers, 10-methacryloxydecyl dihydrogen phosphate (10-MDP) bonded most effectively to hydroxyapatite (HAp). However, more hydrolysis-resistant functional monomers are needed to improve bond durability. Here, we investigated the adhesive potential of the novel fluoro-carbon functional monomer 6-methacryloxy-2,2,3,3,4,4,5,5-octafluorohexyl dihydrogen phosphate (MF8P; Kuraray Noritake Dental Inc., Tokyo, Japan) by studying its molecular interaction with powder HAp using solid-state nuclear magnetic resonance ((1)H MAS NMR) and with dentin using x-ray diffraction (XRD) and by characterizing its interface ultrastructure at dentin using transmission electron microscopy (TEM). We further determined the dissolution rate of the MF8P_Ca salt, the hydrophobicity of MF8P, and the bond strength of an experimental MF8P-based adhesive to dentin. NMR confirmed chemical adsorption of MF8P onto HAp. XRD and TEM revealed MF8P_Ca salt formation and nano-layering at dentin. The MF8P_Ca salt was as stable as that of 10-MDP; MF8P was as hydrophobic as 10-MDP; a significantly higher bond strength was recorded for MF8P than for 10-MDP. In conclusion, MF8P chemically bonded to HAp. Despite its shorter size, MF8P possesses characteristics similar to those of 10-MDP, most likely to be associated with the strong chemical bond between fluorine and carbon. Since favorable bond strength to dentin was recorded, MF8P can be considered a good candidate functional monomer for bonding. PMID:24300311

Yoshihara, K; Yoshida, Y; Hayakawa, S; Nagaoka, N; Kamenoue, S; Okihara, T; Ogawa, T; Nakamura, M; Osaka, A; Van Meerbeek, B

2014-02-01

47

Hyperbranched hydrocarbon surfactants give fluorocarbon-like low surface energies.  

PubMed

Two series of Aerosol-OT-analogue surfactants (sulfosuccinate-type di-BCnSS and sulfoglutarate-type di-BCnSG) with hyperbranched alkyl double tails (so-called "hedgehog" groups, carbon number n = 6, 9, 12, and 18) have been synthesized and shown to demonstrate interfacial properties comparable to those seen for related fluorocarbon (FC) systems. Critical micelle concentration (CMC), surface tension at the CMC (?CMC), and minimum area per molecule (Amin) were obtained from surface tension measurements of aqueous surfactant solutions. The results were examined for relationships between the structure of the hedgehog group and packing density at the interface. To evaluate A and B values in the Klevens equation for these hedgehog surfactants, log(CMC) was plotted as a function of the total carbon number in the surfactant double tail. A linear relationship was observed, producing B values of 0.20-0.25 for di-BCnSS and di-BCnSG, compared to a value of 0.31 for standard double-straight-tail sulfosuccinate surfactants. The lower B values of these hedgehog surfactants highlight their lower hydrophobicity compared to double-straight-tail surfactants. To clarify how hydrocarbon density in the surfactant-tail layer (?(layer)) affects ?CMC, the ?(layer) of each double-tail surfactant was calculated and the relationship between ?CMC and ?(layer) examined. As expected for the design of low surface energy surfactant layers, ?(layer) was identified as an important property for controlling ?CMC with higher ?(layer), leading to a lower ?CMC. Interestingly, surfactants with BC9 and BC12 tails achieved much lower ?CMC, even at low ?(layer) values of <0.55 g cm(-3). The lowest surface energy surfactant studied here was di-BC6SS, which had a ?CMC of only 23.8 mN m(-1). Such a low ?CMC is comparable to those obtained with short FC-tail surfactants (e.g., 22.0 mN m(-1) for the sulfosuccinate-type FC-surfactant with R = F(CF2)6CH2CH2-). PMID:24815218

Sagisaka, Masanobu; Narumi, Tsuyoshi; Niwase, Misaki; Narita, Shioki; Ohata, Atsushi; James, Craig; Yoshizawa, Atsushi; Taffin de Givenchy, Elisabeth; Guittard, Frédéric; Alexander, Shirin; Eastoe, Julian

2014-06-01

48

Measurement of Stimulated Brillouin Scattering Characteristics in Heavy Fluorocarbon Liquids and Perfluoropolyether Liquids  

Microsoft Academic Search

The reflectivity, threshold energy, and Brillouin shift of a stimulated Brillouin scattering (SBS) were measured in new SBS liquid media. The new liquids consist of four heavy fluorocarbon (FC) liquids and six perfluoropolyether (HT) liquids. Among them, FC-77 and HT-70 were found to be good candidates to replace FC-75 which has been known to be a good SBS medium up

Changwhan Lim; Hidetsugu Yoshida; Masahiro Nakatsuka

2006-01-01

49

Release and fate of fluorocarbons in a shredder residue landfill cell: 2. Field investigations.  

PubMed

The shredder residues from automobiles, home appliances and other metal containing products are often disposed in landfills, as recycling technologies for these materials are not common in many countries. Shredder waste contains rigid and soft foams from cushions and insulation panels blown with fluorocarbons. The objective of this study was to determine the gas composition, attenuation, and emission of fluorocarbons in a monofill shredder residue landfill cell by field investigation. Landfill gas generated within the shredder waste primarily consisted of CH(4) (27%) and N(2) (71%), without CO(2), indicating that the gas composition was governed by chemical reactions in combination with anaerobic microbial reactions. The gas generated also contained different fluorocarbons (up to 27 ?g L(-1)). The presence of HCFC-21 and HCFC-31 indicated that anaerobic degradation of CFC-11 occurred in the landfill cell, as neither of these compounds has been produced for industrial applications. This study demonstrates that a landfill cell containing shredder waste has a potential for attenuating CFC-11 released from polyurethane (PUR) insulation foam in the cell via aerobic and anaerobic biodegradation processes. In deeper, anaerobic zones of the cell, reductive dechlorination of CFCs to HCFCs was evident, while in the shallow, oxic zones, there was a high potential for biooxidation of both methane and lesser chlorinated fluorocarbons. These findings correlated well with both laboratory results (presented in a companion paper) and surface emission measurements that, with the exception from a few hot spots, indicated that surface emissions were negative or below detection. PMID:20444588

Scheutz, Charlotte; Fredenslund, Anders M; Nedenskov, Jonas; Kjeldsen, Peter

2010-11-01

50

Long term aging of elastomers: Chemorheology of Viton B fluorocarbon elastomer  

NASA Technical Reports Server (NTRS)

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.

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

1972-01-01

51

Adsorption properties of fluorocarbon thin films prepared by physical vapor deposition methods  

Microsoft Academic Search

To investigate their potential as gas sensors, fluorocarbon thin films were deposited onto the gold electrode of a quartz crystal microbalance by vacuum evaporation (VE), plasma assisted vacuum evaporation (PE-VE) and RF sputtering (RF-SP). The adsorption properties of these thin films for water, ethanol, acetone, acetaldehyde, toluene and methyl salicylate were then evaluated and compared to their surface morphologies. These

Satoru Iwamori; Tomoya Tanabe; Satoshi Yano; Kazutoshi Noda

2010-01-01

52

Influence of electron beam irradiation on the mechanical properties and crosslinking of fluorocarbon elastomer  

Microsoft Academic Search

The influence of electron beam irradiation on the mechanical and dynamic mechanical properties, gel fraction and crosslink density of terpolymeric fluorocarbon rubber has been investigated in this paper. An attempt has been made to correlate the structure of the irradiated rubber with the properties. With increase in radiation dose, an increase in degree of crosslinking results which leads to increase

Indranil Banik; Anil K. Bhowmick

1999-01-01

53

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

ERIC Educational Resources Information Center

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…

Mahaffy, Cheryl

54

The environmental history and probable future of fluorocarbon-11  

NASA Astrophysics Data System (ADS)

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 first occurred around 1974, when trends started falling from their all time high of 13.8 pptv/yr down to around 7.8 pptv/yr (1 pptv = 10-12 parts by volume) in 1982. This decline occurred at first, probably, because of market conditions and later because of the ban in the United States on inessential uses of F-11, particularly in aerosol spray cans. In the meantime, other uses of F-11, such as blowing foams, increased, causing an increasing trend once again until around 1987, when the atmospheric trends reached 11 pptv/yr (measured 1986-1988, inclusive). After this time, however, the trends have fallen dramatically and are now only 4.6 pptv/yr (measured 1990-1992) and even lower in the middle northern latitudes (about 2 pptv/yr). The recent decline of trend is attributed to the effect of the Montreal Protocol and subsequent agreements that are designed to ban worldwide production before the turn of this century. The atmospheric trends reflect estimated emissions, which reached highest values in 1974 (340-355 Gg/yr; 1 Gg = 109g) 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 in 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. At present there are about 5360 Gg in the troposphere, 740 Gg in the stratosphere, and small amounts in the oceans (27 Gg and 6 Gg in the mixed layer and deep oceans, respectively). About 81% of the 9 Tg of F-11 produced is still in the surface or environmental reservoirs (1 Tg = 1012g). 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. The peak concentration is expected to be about 275 pptv and may occur within the next 2 to 3 years. This abstract, the figures, and their captions form a self-contained condensed description of our results.

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

1993-12-01

55

Spatially resolved CF, CF 2, SiF and SiF 2 densities in fluorocarbon containing inductively driven discharges  

Microsoft Academic Search

Laser-induced fluorescence was used to measure the spatially resolved CF, CF2, SiF and SiF2 radical densities in inductively driven discharges containing fluorocarbon gases while etching silicon. Measurements of the spatially resolved radical densities were performed in fluorocarbon containing gases such as C2F6, CHF3 and C4F8 as functions of the induction coil power, pressure and bias power above a silicon surface.

G. A Hebner

2002-01-01

56

Viscosity of saturated liquid fluorocarbon refrigerants from 273 to 353 K  

NASA Astrophysics Data System (ADS)

Viscosity measurements were carried out on saturated liquid fluorocarbon refrigerants using an improved capillary viscometer for 11 kinds of fluorocarbon refrigerants; CCl3F (R11), CCl2F2 (R12), CHClF2 (R22), CBrF3 (R13B1), CH3CHF2 (R152a), CCl2FCClF2 (R113), CHCl2CF3 (R123), CHClFCClF2 (R123a), CH3CF3 (R143a), CClF2CCl2F2 (R114), and CH2FCF3 (R134a), in the temperature range from 273 to 353 K. An equation is given to represent the viscosity as a function of temperature.

Kumagai, A.; Takahashi, S.

1991-01-01

57

Structure of surface reaction layer of poly-Si etched by fluorocarbon plasma  

SciTech Connect

A structure of surface reaction layer of poly-Si substrate during fluorocarbon plasma etching was studied by using a plasma beam irradiation apparatus and a quasi-in situ x-ray photoelectron spectroscopy. A fluorinated silicon (SiF) layer was formed under a fluorocarbon (CF) layer. It was found that the thickness of the SiF layer linearly increased with the etch yield of poly-Si regardless of the change of the CF layer thickness. The average ratio of the number of Si to that of F in the SiF layer did not strongly depend on the etch yield. The carbon-rich region of the CF layer was formed just above the SiF layer due to the consumption of fluorine for the formation of SiF layer.

Kurihara, Kazuaki; Egami, Akihiko; Nakamura, Moritaka [Corporate Research and Development Center, Toshiba Corporation, 8 Shinsugita-cho, Isogo-ku, Yokohama 235-8522 (Japan); Environmentally Benign Etching Technology Laboratory, Association of Super-Advanced Electronics Technologies (ASET), 3-1 Morinosato Wakamiya, Atsugi-shi, Kanagawa 243-0198 (Japan)

2006-03-15

58

Synthesis of ether-linked fluorocarbon surfactants and their aggregational properties in organic solvents  

Microsoft Academic Search

A series of single- and double-tailed hydrocarbon–fluorocarbon (HF) surfactants were prepared to evaluate the effect of molecular structure on aggregate formation in organic solvents. The molecules were designed with ether linkages to permit facile syntheses of both sets of molecules. Solvent foaming studies were used to rapidly assess the surface-active properties of the surfactants, while dynamic light scattering provided quantitative

Wenjian Huang; Chunyang Jin; Dora K. Derzon; Tina A. Huber; Julie A. Last; Paula P. Provencio; Aravamudan S. Gopalan; Michael Dugger; Darryl Y. Sasaki

2004-01-01

59

Aspects of the use of saturated fluorocarbon fluids in high energy physics  

Microsoft Academic Search

The excellent dielectric properties of saturated fluorocarbons have allowed their use in direct immersion liquid cooling of electronics, including supercomputers and as heat transfer media in vapour phase soldering and burn-in testing of electronics. Their high density, UV transparency, non-flammability, non-toxicity and radiation tolerance have led to their use as liquid and gas radiator media for RICH detectors in numerous

G. Hallewell

2011-01-01

60

Chemical structure and morphology of thin bilayer and composite organosilicon and fluorocarbon microwave plasma polymer films  

Microsoft Academic Search

A microwave plasma polymerisation set-up with a linear plasma source was used to deposit thin bilayer and nanocomposite films of fluorocarbon and organosilicon plasma polymers. Hexamethyldisilane (HMDS) and heptadecafluoro-1-decen (HDFD) were used as monomers. The chemical structure was measured by means of Fourier Transformation Infrared Reflection Absorption Spectroscopy (IRRAS), X-ray Photoelectron Spectroscopy (XPS) and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS).

J. Carpentier; G. Grundmeier

2005-01-01

61

Measurement of Stimulated Brillouin Scattering Characteristics in Heavy Fluorocarbon Liquids and Perfluoropolyether Liquids  

NASA Astrophysics Data System (ADS)

The reflectivity, threshold energy, and Brillouin shift of a stimulated Brillouin scattering (SBS) were measured in new SBS liquid media. The new liquids consist of four heavy fluorocarbon (FC) liquids and six perfluoropolyether (HT) liquids. Among them, FC-77 and HT-70 were found to be good candidates to replace FC-75 which has been known to be a good SBS medium up to now.

Park, Hyunmin; Lim, Changwhan; Yoshida, Hidetsugu; Nakatsuka, Masahiro

2006-06-01

62

Microcapsules with compact wall from hydrocarbon\\/fluorocarbon composite surfactants for electrophoretic display  

Microsoft Academic Search

The components and their concentration ratio of surfactant mixture in aqueous solution of gelatin and sodium carboxymethylcellulose\\u000a (NaCMC) are very important during the preparation of stable microcapsules for electrophoretic display. In this work, hydrocarbon\\/fluorocarbon\\u000a composite surfactant was introduced for the first time into the capsule wall to improve the chemical resistance and barrier\\u000a property of the microcapsules. By investigating surface

RunYing Dai; Gang Wu; HongZheng Chen

2011-01-01

63

Mechanisms of High PSG\\/SiO2 Selective Etching in a Highly Polymerized Fluorocarbon Plasma  

Microsoft Academic Search

We have investigated high selective etching mechanisms of phosphosilicate glass (PSG) over SiO2 in a highly polymerized fluorocarbon plasma, by studying the Ar+ induced reactions between the adsorption layer and the underlying substrates with X-ray photoelectron spectroscopy. Both of SiO2 and PSG were found to react in a very near surface region, chiefly with the adsorption layer, by reflecting the

Naokatsu Ikegami; Nobuo Ozawa; Yasuhiro Miyakawa; Jun Kanamori

1991-01-01

64

Electron beam induced structural modification of a fluorocarbon elastomer in the presence of polyfunctional monomers  

Microsoft Academic Search

The influence of polyfunctional monomers—tripropyleneglycol diacrylate (TPGDA), trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimetbacrylate (TMPTMA), tetramethylolmethane tetracrylate (TMMT) and triallyl cyanurate (TAC)—on the structural changes of fluorocarbon terpolymer (F content 68%, H 1.4%) in the presence of an electron beam has been investigated with the help of IR spectroscopy (in the ATR mode) and sol-gel analysis. The absorbances at 1397, 1021, 672

I. Banik; S. K. Dutta; T. K. Chaki; Anil K. Bhowmick

1999-01-01

65

Association of nonionic polymer with hydrocarbon\\/fluorocarbon surfactant in aqueous solution  

Microsoft Academic Search

The interaction between a nonionic polymer and a hydrocarbon or fluorocarbon surfactant has been investigated by means of\\u000a surface tension, viscosity, electroconductivity, fluorescence probing, solubilization of a waterinsoluble dye, and electron\\u000a spin resonance (ESR). The systems studied consisted of polyvinylpyrrolidone (PVP) with lithium dodecyl sulfate (LiDS) or lithium\\u000a perfluorooctane sulfonate (LiFOS). Surface tension measurements indicated that formation of PVP-surfactant complex

Takahiko Nojima; Kunio Esumi; Kenjiro Meguro

1992-01-01

66

Total electron scattering cross section of Fluorocarbons at intermediate electron energies  

NASA Astrophysics Data System (ADS)

Total electron scattering cross sections (TCS) of Tetrafluoromethane (CF4), Trifluoromethane (CHF3), Hexafluoroethane (C2F6) and Octafluorocyclobutane (C4F8) have been measured using the linear transmission technique for impact energies 0.10 -- 4.00 keV. These TCS are compared to existing experimental and theoretical TCS in the literature. Based on the present measurements, an empirical formula is developed to predict the TCS of fluorocarbons as a function of incident electron energy.

Palihawadana, Prasanga; Villela, Gilberto; Ariyasinghe, Wickramasinghe

2008-10-01

67

Understanding the effect of fluorocarbons in aqueous supramolecular polymerization: ultrastrong noncovalent binding and cooperativity.  

PubMed

Achieving supramolecular polymerization based on strong yet reversible bonds represents a significant challenge. A solution may be offered by perfluoroalkyl groups, which have remarkable hydrophobicity. We tested the idea that a perfluorooctyl chain attached to a perylene diimide amphiphile can dramatically enhance the strength of supramolecular bonding in aqueous environments. Supramolecular structures and polymerization thermodynamics of this fluorinated compound (1-F) were studied in comparison to its non-fluorinated analogue (1-H). Depending on the amount of organic cosolvent, 1-F undergoes cooperative or isodesmic aggregation. The switching between two polymerization mechanisms results from a change in polymer structure, as observed by cryogenic electron microscopy. 1-F showed exceptionally strong noncovalent binding, with the largest directly measured association constant of 1.7 × 10(9) M(-1) in 75:25 water/THF mixture (v/v). In pure water, the association constant of 1-F is estimated to be at least in the order of 10(15) M(-1) (based on extrapolation), 3 orders of magnitude larger than that of 1-H. The difference in aggregation strength between 1-F and 1-H can be explained solely on the basis of the larger surface area of the fluorocarbon group, rather than a unique nature of fluorocarbon hydrophobicity. However, differences in aggregation mechanism and cooperativity exhibited by 1-F appear to result from specific fluorocarbon conformational rigidity. PMID:24915305

Krieg, Elisha; Weissman, Haim; Shimoni, Eyal; Bar On Ustinov, Alona; Rybtchinski, Boris

2014-07-01

68

Characterization of Polymer Thin Films Prepared with RF Sputtering with Fluorocarbon Polymer Targets  

NASA Astrophysics Data System (ADS)

Polymer thin films were prepared by RF sputtering with argon (Ar) and tetra-fluorocarbon (CF4) gases. Four fluorocarbon polymers, poly(tetra fluoro ethylene) (PTFE), tetra fluoro ethylene-perfluoro alkylvinyl ether copolymer (PFA), fluorinated ethylene propylene copolymer (FEP), poly(vinylidene di fluoride) (PVDF) were used as the sputtering targets. Molecular structures of sputtered fluorocarbon thin films were analyzed with x-rays photoelectron spectroscopy (XPS) and fourier transform infrared spectroscopy (FT-IR). Wettability of these polymer thin films was estimated with contact angles of water droplets. The contact angles increased with increase of the F/C ratio (fluorine for carbon) of the thin film. PTFE target prepared by a spin coat method was also used for the sputtering target, and analyzed the elemental compositions of the target after the sputtering. The F/C ratio of the polymer thin film prepared by the sputtering with CF4 was almost the same value as that of the thin film with Ar. However, the C/F ratio of the target after the CF4 sputtering was much higher than that after the Ar sputtering.

Kezuka, Kazuya; Uemura, Akihiro; Iwamori, Satoru

69

Synthesis and applications of vegetable oil-based fluorocarbon water repellent agents on cotton fabrics.  

PubMed

Vegetable oil-based fluorocarbon water repellent agents were prepared by chemical modifications of different vegetable oils - soybean and linseed oils through several reactions, including saponification, acidification, acylation of vegetable oil and trans-esterification with 2,2,2-trifluoroethanol and 2,2,3,3-tetrafluoropropanol. The resulted fluorocarbon agents were then copolymerized with styrene. The structures of the vegetable oil based agents were characterized by FT-IR and NMR. By evaluating water contact angle and time of water disappearance on cotton fabrics, as well as whiteness and breaking strength of cotton fabrics that were treated by these agents, optimum fabric finishing conditions were explored. The cotton fabrics finished with the vegetable oil-based fluorocarbon agents showed excellent water repellency, while other properties of the cotton fabrics declined to certain level. The linseed oil-based tetrafluoropropanol water repellent agent displayed the highest water repellency among all modified oils. All the treated fabrics exhibited good durability of water repellency. The linseed oil-based tetrafluoropropanol water repellent agent demonstrated the best durability among all repellent agents. PMID:24750623

Zhao, Tao; Zheng, Junzhi; Sun, Gang

2012-06-01

70

Fluorocarbon nano-coating of polyester fabrics by atmospheric air plasma with aerosol  

NASA Astrophysics Data System (ADS)

A fluorocarbon coating was deposited on polyester (PET) woven fabric using pulse discharge plasma treatment by injecting a fluoropolymer directly into the plasma dielectric barrier discharge. The objective of the treatment was to improve the hydrophobic properties as well as the repellent behaviour of the polyester fabric. Plasma treatment conditions were optimised to obtain optimal hydrophobic properties which were evaluated using water contact angle measurement as well as spray-test method at the polyester fabric surface. The study showed that adhesion of the fluoropolymer to the woven PET was greatly enhanced by the air plasma treatment. X-ray photoemission spectroscopy (XPS) analyses revealed chemical surface modifications occurring after the plasma treatments.

Leroux, F.; Campagne, C.; Perwuelz, A.; Gengembre, L.

2008-04-01

71

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

SciTech Connect

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.

Hogen-Esch, T.E.

1996-11-01

72

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

NASA Technical Reports Server (NTRS)

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.

Alston, W. B.

1973-01-01

73

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

NASA Astrophysics Data System (ADS)

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.

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

2010-04-01

74

Effects of fluorocarbons, chlorinated solvents, and inosine on the cardiopulmonary system  

PubMed Central

The effects of fluorocarbons and chlorinated solvents on the cardiopulmonary system are reviewed. The new information, not hitherto reported, relates to the antagonistic action of inosine, a naturally occurring nucleoside formed in the body by deamination of adenosine. The effect of inosine on methylene chloride toxicity was investigated in open chest dogs anesthetized with pentobarbital sodium. Methylene chloride (5% in air or 50,000 ppm) elicited a decrease of ventricular contractility represented by the diminished left ventricular (dp/dt)max and myocardial contractile force measured directly with a Walton-Brodie strain gauge arch. Coronary blood flow decreased slightly after exposure to methylene chloride. Arterial blood pressure and heart rate did not change. The negative inotropic effect of methylene chloride was reversed or prevented to a substantial extent by intravenous infusion of inosine (5 mg/kg-min). The effect of the latter compound was also characterized by significant coronary vasodilation. It was shown by the experiments that the cardiostimulatory action of inosine was associated with improved hypoxic adaptability of the coronary blood vessels. In contrast, the effect of catecholamines (epinephrine and isoproterenol) was not accompanied by such a beneficial coronary vascular effect. On the basis of these results, the conclusion has been arrived at that inosine might be recommended as a useful antidote in methylene chloride poisoning in particular, and of poisoning by chlorinated solvents and fluorocarbons in general.

Aviado, Domingo M.

1978-01-01

75

Manipulation of the bombarding ion energy distribution in fluorocarbon plasma etching  

NASA Astrophysics Data System (ADS)

Ion bombardment is a key element of plasma etching for microelectronics fabrication and other materials processing applications. A sinusoidal voltage waveform typically produces a broad ``bimodal'' ion energy distribution (IED) at the substrate, with two ion flux maxima, at respective energies considerably above and below the average. In order to deconvolve the effect of ions of multiple energies bombarding the substrate simultaneously, we have manipulated the waveform of the bias voltage to produce two ion flux maxima. By systematically tailoring the shape of the waveform, the energies and relative fluxes of the two IED peaks are varied independently over a 100 to 500 eV range in a fluorocarbon-based helicon plasma, while silicon dioxide and photoresist etch rates are monitored. Two experiments were conducted in which a 100 eV IED peak was combined with a higher energy peak, while the energy and relative flux of the high energy peak were respectively varied. In both cases, a relatively small contribution of high energy ions leads to etch rate enhancement higher than predicted by a linear combination of single peak etch rates at the two energies. We speculate that high energy ion bombardment suppresses fluorocarbon deposition, enabling lower energy ions to more effectively contribute to etching reactions.

Wendt, Amy; Buzzi, Frank; Ting, Yuk-Hong

2008-10-01

76

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

Microsoft Academic Search

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

Satoru Iwamori; Norihiko Hasegawa; Satoshi Yano; Kazutoshi Noda

2010-01-01

77

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

PubMed

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

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

2014-04-01

78

Study of micelle formation by fluorocarbon surfactant N-(2-hydroxypropyl)perfluorooctane amide in aqueous solution.  

PubMed

Micelles formed by fluorocarbon surfactant N-(2-hydroxypropyl)perfluorooctane amide in aqueous solution were studied through surface tension, dynamic light scatting (DLS), isothermal titration calorimetry (ITC), and dissipative particle dynamic (DPD) simulations. Through surface tension measurements, the effectiveness of surface tension reduction, the maximum surface excess concentration, and the minimum area occupied per surfactant molecule at the air/water interface were investigated. The critical micelle concentration (cmc) at different temperatures and a series of thermodynamic parameters (?G(m)0, ?H(m)0, ?S(m)0, ?G(ads)0, ?H(m)(A) and ?C(p(m))0) of micellization were evaluated. The thermodynamic parameters showed that the micelle formation was entropy-driven. The micelle formation was also confirmed by ITC and DLS. In addition, the DPD simulations were conducted to simulate the whole process of micelle formation to make micelle formation better understood. PMID:23909751

Dai, Caili; Du, Mingyong; Zhao, Mingwei; You, Qing; Guan, Baoshan; Wang, Xin; Liu, Ping

2013-08-29

79

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

SciTech Connect

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.

Ewing, J.R.; Branch, C.A.; Fagan, S.C.; Helpern, J.A.; Simkins, R.T.; Butt, S.M.; Welch, K.M. (Henry Ford Hospital, Detroit, MI (USA))

1990-01-01

80

Modification of the biocompatible and haemocompatible properties of polymer substrates by plasma-deposited fluorocarbon coatings.  

PubMed

The polymerization of gases present in a low temperature plasma is a technique particularly well suited for biomedical material processing. Therefore, the possibilities this technique offers to increase the biocompatibility and haemocompatibility of polysulphone and poly(hydroxybutyrate) membranes to be used in a new bioartificial pancreas device were studied. The deposition of thin fluorocarbon coatings from an argon plasma containing perfluorohexane gave very smooth and hydrophobic surfaces without affecting the filtering properties of the treated membranes. Adding hydrogen increased the reaction yield, but gave rougher and less hydrophobic coatings. We characterized the biological properties of the treated surfaces and discussed the influence of the modified surface properties on the biological behaviour of the treated polymers. The good biocompatibility of the deposited coatings was established by following in vitro the insulin secretion of Langerhans islets cultured on the treated membranes and by examining the fibrous capsule that developed on plasma-treated polymer disks after three months of in vivo incubation in the peritoneum of Wistar rats. Rough and haemocompatible films of poly(hydroxybutyrate) and smoother, but more thrombogenic, polysulphone films were treated by perfluorohexane and perfluorohexane + H2 plasmas to study the relative influence of surface roughness and surface energy on polymer thrombogenicity. In vitro protein adsorption and total blood clotting tests proved that the surface roughness influences the thrombogenicity more than the other surface properties. This study seems to show that the plasma deposition of smooth and hydrophobic fluorocarbon coatings can increase the biocompatibility and reduce the surface thrombogenicity of the treated membranes without affecting their filtering properties. PMID:1457676

Clarotti, G; Schue, F; Sledz, J; Ait Ben Aoumar, A; Geckeler, K E; Orsetti, A; Paleirac, G

1992-01-01

81

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

SciTech Connect

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.

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

2010-01-01

82

Influence of the RF power on the deposition rate and the chemical surface composition of fluorocarbon films prepared in dry etching gas plasma  

Microsoft Academic Search

Fluorocarbon (FC) films have technological applications in various fields such as microelectronics and MicroElectroMechanical Systems (MEMS). In this study, thin FC-films were deposited via plasma polymerisation of trifluoromethane (CHF3) onto Si(111) in a commercial reactive ion etcher (RIE, radio-frequency RF=13.56 MHz). The behaviour of the fluorocarbon deposition rate and the chemical composition as a function of the RF-power was investigated.

V. Yanev; S. Krischok; A. Opitz; H. Wurmus; J. A. Schaefer; N. Schwesinger; S.-I.-U. Ahmed

2004-01-01

83

Fabrication of fluorocarbon polymer-coated silver hollow-glass waveguides for the infrared by the liquid-phase coating method  

NASA Astrophysics Data System (ADS)

Fluorocarbon polymer-coated silver hollow-glass waveguides have been fabricated based on the method of silver mirror reaction for silver, and the dipping method for the fluorocarbon polymer. The waveguides show low-loss properties for the infrared wavelengths except for the wavelength regions of large absorption of the polymer. Er:YAG laser light has been successfully transmitted through the flexible waveguides with small bending losses.

Osawa, M.; Kato, Y.; Watanabe, T.; Miyagi, M.; Abe, S.; Aizawa, M.; Onodera, S.

1995-12-01

84

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

PubMed

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

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

2014-05-01

85

Thermal behavior and high- and low-temperature phase structures of gemini fluorocarbon/hydrocarbon diblocks.  

PubMed

The thermal behavior and phase structure of two series of gemini fluorocarbon/hydrocarbon diblock amphiphiles with the general formula (CnF2n+1CH2)(Cm - 2H2m - 3)CH-CH(CnF2n+1CH2)(Cm - 2H2m - 3), with n = 8, 10 and m = 6, 12, 14, 16, 18, 20 (abbreviated as di(FnHm)), have been investigated by differential scanning calorimetry, polarized optical and freeze-fracture transmission electron microscopies, dilatometry, and small-angle X-ray scattering (SAXS). The various terms of the series exhibit the same thermal behavior, essentially composed of two exothermal transitions, a low-temperature event that corresponds to the melting of the hydrocarbon chains at TH and a high-temperature transition associated with the melting of the fluorocarbon chains at TF. Below TH, a disordered plastic rotator phase, MLT, and above TH, a lamellar phase, MHT, were determined by SAXS experiments. Above TF, the compounds eventually clear into the isotropic liquid. In the MHT phase, both the Fn and Hm blocks are segregated from each other, forming sublayers with sharp interfaces, as revealed by the five lamellar orders and remarkable sharpness of the SAXS peaks. In the MLT phase, the partial crystallization of the aliphatic blocks when the temperature is lowered leads to the disruption of the aliphatic sublayers into rows of ribbons arranged according to pseudohexagonal and/or rectangular arrangements with different lattice sizes (p2gg symmetry). The Fn segments form the fluorinated continuum. In support of SAXS, molecular packing models of the tetrablocks are proposed on the basis of the temperature/volume variations of di(F10H20) and di(F10H16) in both high- and low-temperature phases, as determined by dilatometry. It is notable that the arrangements found for di(FnHm) are completely different from those previously reported for FnHm diblocks, revealing the influence of the linker unit on the solid-state behavior of the tetrablocks. PMID:23600621

de Gracia Lux, Caroline; Donnio, Bertrand; Heinrich, Benoit; Krafft, Marie Pierre

2013-04-30

86

Study of Silicon Dioxide to Silicon Etching Selectivity in High Density, Low Pressure Fluorocarbon Plasmas  

NASA Astrophysics Data System (ADS)

To facilitate the development of commercially viable processes for high plasma density, low pressure source designs it is necessary to understand the mechanisms that contribute to the selective etching of SiO _2 over Si. This study examines the gas phase chemical species and mechanisms influencing SiO _2 to Si selectivity in CF_4 , CHF_3, (1,1,1,2-Tetrafluoroethane)C _2H_2F_4, and CH_3F discharges generated by a high plasma density, low pressure source. To modulate the selectivity, H_2 and O _2 were added to these fluorocarbon gases. To distinguish between potential selectivity mechanisms, etch rate measurements of Si and SiO_2 were combined with chemical characterization of an electron cyclotron resonance (ECR) discharge using optical diagnostics and an in-line quadrupole mass spectrometer (QMS). The gas phase concentrations of CF_2, CF, and F as well as the mass spectra of neutral and ion species incident to the substrate have been measured for conditions producing SiO_2 to Si selectivities from 1 to over 100. A calibration of the mass sensitivity of the QMS diagnostic has been developed which, in conjunction with the QMS ion measurements, allows the quantitative determination of the ion chemical composition. The data presented demonstrate that ions as well as neutrals may contribute to selectivity for these sources. For the parameter range studied, the fluxes of fluorocarbon ion species such as CF^+ correlate with the observed selectivities suggesting that these species influence the selective etching of SiO_2 over Si by contributing to the formation of passivating films on Si surfaces. In contrast, variations in the concentrations of the CF_2 and CF radicals, neutral species which were expected to influence selectivity, were not consistent with the selectivities observed. The data presented suggest that the selectivity increase associated with increased H_2 addition is caused by increases in the ratio of numbers of carbon to fluorine atoms (C:F ratio) contained in the ion and neutral radical fluxes to the substrate. In contrast, when O_2 is added to the feed gas direct etching of passivating films on silicon surfaces by oxygen containing radicals appears, in addition to the C:F ratio, to be an important factor in determining selectivity.

Kirmse, Karen Hildegard Ralston

87

Electrowetting on plasma-deposited fluorocarbon hydrophobic films for biofluid transport in microfluidics  

NASA Astrophysics Data System (ADS)

The present work focuses on the plasma deposition of fluorocarbon (FC) films on surfaces and the electrostatic control of their wettability (electrowetting). Such films can be employed for actuation of fluid transport in microfluidic devices, when deposited over patterned electrodes. Here, the deposition was performed using C4F8 and the plasma parameters that permit the creation of films with optimized properties desirable for electrowetting were established. The wettability of the plasma-deposited surfaces was characterized by means of contact angle measurements (in the static and dynamic mode). The thickness of the deposited films was probed in situ by means of spectroscopic ellipsometry, while the surface roughness was provided by atomic force microscopy. These plasma-deposited FC films in combination with silicon nitride, a material of high dielectric constant, were used to create a dielectric structure that requires reduced voltages for successful electrowetting. Electrowetting experiments using protein solutions were conducted on such optimized dielectric structures and were compared with similar structures bearing commercial spin-coated Teflon® amorphous fluoropolymer (AF) film as the hydrophobic top layer. Our results show that plasma-deposited FC films have desirable electrowetting behavior and minimal protein adsorption, a requirement for successful transport of biological solutions in ``digital'' microfluidics.

Bayiati, P.; Tserepi, A.; Petrou, P. S.; Kakabakos, S. E.; Misiakos, K.; Gogolides, E.

2007-05-01

88

Synthesis of ether-linked fluorocarbon surfactants and their aggregational properties in organic solvents.  

PubMed

A series of single- and double-tailed hydrocarbon-fluorocarbon (HF) surfactants were prepared to evaluate the effect of molecular structure on aggregate formation in organic solvents. The molecules were designed with ether linkages to permit facile syntheses of both sets of molecules. Solvent foaming studies were used to rapidly assess the surface-active properties of the surfactants, while dynamic light scattering provided quantitative critical micelle concentrations (CMC) and hydrodynamic radius (R(h)) measurements of the aggregates in solution. The single-tailed surfactants did not produce any foaming action in a number of hydrocarbon solvents, nor was any micellar formation observed up to 100 mM concentrations. Double-tailed surfactants, on the other hand, gave low CMC values in dodecane but with R(h) values that indicated a tight micelle structure. Bilayer formation was expected but not observed for these molecules, which is believed to be due to their unusual structural geometry, imparted by the glycerol backbone. No thermotropic liquid crystalline (LC) behavior was observed for any of the single- or double-tailed molecules. These data contrast with the known behavior of perfluorinated alkanes and other fluorinated surfactants, suggesting that the ether linkage plays an important role in the self-organizing behavior of these molecules. PMID:15028511

Huang, Wenjian; Jin, Chunyang; Derzon, Dora K; Huber, Tina A; Last, Julie A; Provencio, Paula P; Gopalan, Aravamudan S; Dugger, Michael; Sasaki, Darryl Y

2004-04-15

89

Comparative study of plasma-deposited fluorocarbon coatings on different substrates  

NASA Astrophysics Data System (ADS)

The deposition of hydrophobic fluorocarbon coatings from C2F6 and C2F6-H2 rf discharges on different substrates was examined. Polyester textile, glass and two different ceramic compounds were used as substrates. The effect of the total gas pressure, the rf power dissipation and the deposition time on the hydrophobic character of the samples was investigated. Films deposited on polyester textiles at low pressure (0.03 mbar) and power consumption (16 mW cm-2) using pure C2F6 presented the highest water contact angles (~150°). On the other hand, the addition of hydrogen was necessary in order to deposit stable hydrophobic coatings on glass and ceramic substrates. Coatings deposited on glass at intermediate deposition rates (~100 Å min-1) and pressures presented the highest angles (~105°). Concerning the heavy clay ceramics, samples treated in low-pressure (0.05 mbar) and low-power (16 mW cm-2) discharges showed the highest contact angles. The deposition time was found to play an important role in the hydrophobicity and long-term behaviour of porous and rough substrates.

Farsari, E.; Kostopoulou, M.; Amanatides, E.; Mataras, D.; Rapakoulias, D. E.

2011-05-01

90

Analysis of the surface reactions of ArF photoresist during fluorocarbon plasma etching by XPS  

NASA Astrophysics Data System (ADS)

High-aspect ratio pattern etching processes with nano-scale accuracy is desired in such as a contract hole etching for the silicon dioxide that is used as a dielectric passivation layer over MOSFETs. However, photoresist used in the advanced ArF lithography is not tolerant enough for plasma etching processes, and it often causes deformations in the etched feature with bowing, distortion, twisting and so on. It is important to investigate the reaction of photoresist with fluorocarbon to overcome these problems and realize sophisticated etch processes. In this research, the modified layer of the photoresist by bombardment of CFx^+ ions was analyzed. The ions, such as CF^+, CF2^+, CF3^+, and F^+, were produced from CF4 gas by electron impact, and selected by quadrupole mass filter. The CFx^+ ions were bombarded to ArF photoresist as ion beam with an accelerated energy from 100 to 400 eV. The equipment system is evacuated by four turbo molecular pumps. Ultimate pressure of the equipment is lower than 10-9 Torr. The beam equipment and XPS analysis chamber are connected in vacuum, so we can use XPS analysis without atmospheric influence after the ion etch process. In this study, we investigated the modified layer of the photoresist by in-situ XPS.

Takeuchi, Takuya; Sekine, Makoto; Toyoda, Hirotaka; Takeda, Keigo; Hori, Masaru; Kang, Song-Yun; Sawada, Ikuo

2009-10-01

91

Global warming implications of non-fluorocarbon technologies as CFC replacements  

SciTech Connect

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.

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

1993-12-31

92

Influence of electron beam irradiation on the mechanical properties and crosslinking of fluorocarbon elastomer  

NASA Astrophysics Data System (ADS)

The influence of electron beam irradiation on the mechanical and dynamic mechanical properties, gel fraction and crosslink density of terpolymeric fluorocarbon rubber has been investigated in this paper. An attempt has been made to correlate the structure of the irradiated rubber with the properties. With increase in radiation dose, an increase in degree of crosslinking results which leads to increase in modulus and Tg with a corresponding decrease in elongation at break, set and tan ?. The effect of multifunctional monomer is realized only at relatively higher level of trimethylolpropane triacrylate (TMPTA), where improvement in strength and failure properties is observed. The dynamic storage modulus at 50°C is higher and loss tangent becomes lower. Among the various polyfunctional monomers tripropyleneglycol diacrylate (TPGDA), trimethylolpropane triacrylate (TMPTA) and tetramethylolmethane tetracrylate (TMMT), the mechanical properties and the degree of crosslinking are lowest for systems based on TPGDA. MgO used in the formulation leads to the improvement in mechanical properties. Increase in the crosslink density is in line with reduced loss tangent and increased storage modulus for the MgO filled rubber vulcanizate.

Banik, Indranil; Bhowmick, Anil K.

1999-01-01

93

Selective adsorption of fluorocarbons and its effects on the adhesion of plasma polymer protective coatings  

NASA Astrophysics Data System (ADS)

Cathodic DC plasma deposited films have shown promise as intermediate adhesion and barrier layers for use in the interface engineering of corrosion protection systems on various materials. The surface treatment of plasma deposited trimethylsilane (TMS) films with various post-deposition plasma treatments can improve the adhesion of various paints to these films, which are usually strongly adhered to underlying substrates. Research into the application of these systems for corrosion protection of aluminum alloys included post-deposition treatments of the TMS films with hexafluoroethane (HFE) plasmas, which was seen to significantly improve the adhesion of primers. Oxygen plasma cleaning of the alloy surfaces, prior to deposition of the TMS film, is normally employed to remove organic contaminants. During testing of sample aluminum panels, one batch was processed without the oxygen plasma treatment and exhibited extensive adhesion failures. The investigation of these results shows that low levels of fluorocarbon contaminants readily react with the alloy surface and deposit a fluorine containing carbonaceous layer, which dramatically interferes with the adhesion of the plasma polymer to the alloys, but the adhesion with primer coatings remains tenacious. X-ray photoelectron spectroscopy (XPS) studies also show that the presence of even low levels of these contaminants in the chamber, during the oxygen cleaning process, is sufficient to induce the conversion of the surface from oxide to a mixture of oxide and fluoride. This conversion is considered detrimental to the corrosion resistance of these systems.

Moffitt, C. E.; Reddy, C. M.; Yu, Q. S.; Wieliczka, D. M.; Yasuda, H. K.

2000-07-01

94

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

SciTech Connect

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.

Agarwal, Ankur; Kushner, Mark J. [University of Illinois, Department of Chemical and Biomolecular Engineering, Urbana, Illinois 61801 (United States); Iowa State University, Department of Electrical and Computer Engineering, 104 Marston Hall, Ames, Iowa 50011-2151 (United States)

2005-09-15

95

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

NASA Astrophysics Data System (ADS)

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.

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

2005-07-01

96

Composite fluorocarbon membranes by surface-initiated polymerization from nanoporous gold-coated alumina.  

PubMed

This manuscript describes the versatile fabrication and characterization of a novel composite membrane that consists of a porous alumina support, a 100 nm thick nanoporous gold coating, and a selective poly(5-(perfluorohexyl)norbornene) (pNBF6) polymer that can be grown exclusively from the nanoporous gold or throughout the membrane. Integration of the three materials is achieved by means of silane and thiol chemistry, and the use of surface-initiated ring-opening metathesis polymerization (SI-ROMP) to grow the pNBF6. The use of SI-ROMP allows tailoring of the extent of polymerization of pNBF6 throughout the structure by varying polymerization time. Scanning electron microscopy (SEM) images indicate that the thin polymer films cover the structure entirely. Cross-sectional SEM images of the membrane not only corroborate growth of the pNBF6 polymer within both the porous alumina and the nanoporous gold coating but also show the growth of a pNBF6 layer between these porous substrates that lifts the nanoporous gold coating away from the alumina. Advancing contact angle (?(A)) measurements show that the surfaces of these composite membranes exhibit both hydrophobic (?(A) = 121-129)° and oleophobic (?(A) = 69-74)° behavior due to the fluorocarbon side chains of the pNBF6 polymer that dominate the surface. Results from electrochemical impedance spectroscopy (EIS) confirm that the membranes provide effective barriers to aqueous ions, as evidenced by a resistive impedance on the order of 1 × 10(7) ? cm(2). Sulfonation of the polymer backbone substantially enhances ion transport through the composite membrane, as indicated by a 40-60 fold reduction in resistive impedance. Ion transport and selectivity of the membrane change by regulating the polymerization time. The fluorinated nature of the sulfonated polymer renders the membrane selective toward molecules with similar chemical characteristics. PMID:22195729

Escobar, Carlos A; Zulkifli, Ahmad R; Faulkner, Christopher J; Trzeciak, Alex; Jennings, G Kane

2012-02-01

97

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

NASA Technical Reports Server (NTRS)

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.

Zellner, Reinhard

1990-01-01

98

Fluorocarbon materials produced by the thermo destruction of polytetrafluoroethylene and possibility of theirs application in Li/(CFx)n batteries  

NASA Astrophysics Data System (ADS)

A few fluorocarbon compounds (CFx)n were produced by the original thermo-gas-dynamic destruction (TD) of polytetrafluoroethylene (PTFE) at the high temperatures 530 and 550 °C. The chemical composition, electrochemical and morphological properties of such materials were characterized by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM)/X-ray energy dispersive spectroscopy (XEDS) and compared to commercial fluorinated petroleum coke (CF1)n. The possibility of the application of the new obtained compounds as the cathode materials in primary lithium batteries was estimated. The differences of the investigated samples properties, which observed during electrochemical tests, are discussed.

Gnedenkov, S. V.; Tsvetnikov, A. K.; Opra, D. P.; Sinebryukhov, S. L.; Sergienko, V. I.

99

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

PubMed

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

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

2013-05-01

100

High-Power Operation of 1 cm Laser Diode Bars on Funryu Heat Sink Cooled by Fluorocarbons  

NASA Astrophysics Data System (ADS)

We have investigated the properties of fluorocarbons as coolants for a high-power laser diode bar mounted on a funryu-jet heat sink. The thermal conductivities of fluorocarbons are about ten times lower than that of water, but they are less corrosive to the funryu copper heat sink and their boiling points may be higher than that of water. Since the cooling efficiency of such a high power laser diode (LD) bar may be a result of the dynamic viscosity, the heat capacity, the thermal resistance, and the boiling temperature of the coolant, we have compared two types of “Fluorinert”, 3M’s FC77 and FC43, and water as coolants. Wavelength distributions along a 1 cm bar, operated under a 52 A driving current, are measured to be ± 1.1 nm for FC77, ± 2.1 nm for FC43 and ± 0.6 nm for water. From their thermal and material characteristics given by 3M, the lower viscosity of FC77 is important for our \\textit{funryu} heat sink, which has a high flow resistance. A thermal resistance of 0.7°C/W is achieved at a flow rate of 1.0 L/min for FC77. FC77 is adopted as the coolant for CW 30 W operation and has operated continuously for over 800 h.

Miyajima, Hirofumi; Suzuki, Noriyasu; Oh-ishi, Satoru; Itoh, Hiroaki; Kan, Hirofumi; Yamanaka, Masanobu; Izawa, Yasukazu

2005-07-01

101

Self-assembly of a fluorocarbon-hydrocarbon hybrid surfactant: dependence of morphology on surfactant concentration and time.  

PubMed

The morphologies of aggregates formed from a hybrid surfactant (F6H5OS) whose molecules have a hydrocarbon chain (pentyl group) and a fluorocarbon chain (perfluorohexyl group) were studied along with changes in the morphologies with time. F6H5OS exhibits a micelle-vesicle transition at a concentration of 5.5 mM in water. Cryo-TEM observation of 5 mM aqueous F6H5OS solution reveals the existence of only micelles with a diameter of ca. 6 nm, while the coexistence of micelles and vesicles is observed in 10 mM aqueous F6H5OS solution. When the 10 mM aqueous F6H5OS solution is aged, the micelles are transformed into vesicles. Further, the vesicles have different structures, namely, spherical and tubular structures. (1)H NMR, (1)H-(1)H NOESY, and FT-IR experiments suggest that upon aging, the conformation of hydrocarbon chains in F6H5OS changes, and the hydrocarbon chains are located close to the phenyl group in the surfactant molecules. At concentrations above 5.5 mM, small micelles are formed immediately after the preparation of the F6H5OS solutions; those micelles subsequently transform into vesicles. The hybridity of F6H5OS, i.e., having a fluorocarbon chain and a hydrocarbon chain in its molecule, plays an important role in the transformation of micelles into vesicles upon aging. PMID:20882953

Takahashi, Yutaka; Kondo, Yukishige; Schmidt, Judith; Talmon, Yeshayahu

2010-10-28

102

Electron-phonon interactions in charged cubic fluorocarbon cluster, (CF)8  

NASA Astrophysics Data System (ADS)

Electron-phonon interactions in the charged cubic fluorocarbon, (CF)8 are studied, and compared with those in charged (CH)8 and (CD)8. The A1g mode of 1470 cm-1 much more strongly couples to the a1g lowest unoccupied molecular orbitals (LUMO) than the A1g mode of 554 cm-1 in (CF)8. The T2g mode of 1030 cm-1, the Eg mode of 980 cm-1, and the A1g mode of 1470 cm-1 strongly couple to the t2u highest occupied molecular orbitals (HOMO) in (CF)8. The total electron-phonon coupling constants for the monoanion (l-1) and monocation (l+1) of (CF)8 are estimated to be 0.932 and 0.585 eV, respectively. The logarithmically averaged phonon frequencies for the monoanion (?ln,-1) and monocation (?ln,+1) of (CF)8 are estimated to be 1365 and 998 cm-1, respectively. The l-1 and ?ln,-1 values increase much more significantly by H-F substitution than by H-D substitution in cubane. The larger displacements of carbon atoms in the high frequency vibronic active mode in (CF)8 than those in (CD)8 due to larger atomic mass of fluorine than that of deuterium, and the unchanged electron distributions in the LUMO somewhat localized on carbon atoms as a consequence of H-F and H-D substitution in cubane, are the main reason why the l-1 and ?ln,-1 values increase much more significantly by H-F substitution than by H-D substitution. The l+1 and ?ln,+1 values less significantly change than the l-1 and ?ln,-1 values by H-F substitution as well as by H-D substitution in cubane. This is because the t2u HOMO in (CF)8 and the t2g HOMO in (CH)8 are somewhat localized on fluorine atoms, and thus, the high frequency vibronic active modes in which the displacements of carbon atoms are large cannot necessarily very strongly couple to the HOMO somewhat localized on fluorine atoms in (CF)8.

Kato, Takashi; Yamabe, Tokio

2004-01-01

103

NO contributes to neurohypophysial but not other regional cerebral fluorocarbon-induced hyperemia in cats.  

PubMed

The large increase in cerebral blood flow (CBF) after fluorocarbon (FC)-exchange transfusion is thought to be caused by low oxygen content, decreased viscosity, or direct vasodilatory effect of the FC perfusate. The aim of this study was to determine whether nitric oxide (NO)-mediated vasorelaxation is increased in FC-perfused hemoglobin (Hb)-free cats because NO is not scavenged by Hb. We measured regional CBF with radiolabeled microspheres in three groups of anesthetized mechanically ventilated cats. The first group [FC + N(omega)-nitro-L-arginine methyl ester (L-NAME), n = 7] underwent a complete FC-exchange transfusion with FC-43 and subsequent nitric oxide synthase (NOS) inhibition with L-NAME (10 mg/kg i.v.) followed by L-arginine (100 mg/kg i.v.). A second group (FC + saline; n = 6) underwent an identical protocol, but NOS was not antagonized (saline i.v.). In a third group (blood + L-NAME; n = 7), cats were not FC exchanged but NOS was inhibited. In a separate cohort of four FC-perfused cats, NOS activity in brain tissue samples was reduced to 26% of control after NOS inhibition. FC-exchange transfusion nearly doubled hemispheric blood flow in both FC-exchanged groups, whereas it was constant in the blood + L-NAME group. These increases in regional CBF (hemispheres, brain stem, cerebellum, thalamus, and white matter) were not reversed by inhibition of NOS, except in the neurohypophysis, where L-NAME reduced blood flow to levels comparable to values in the blood + L-NAME group. In summary, increases in regional CBF after total FC-exchange transfusion are not caused by a lack of NO scavenging, with the exception of neurohypophysis. These findings suggest an increased vasorelaxation in neurohypophysis of FC-perfused and Hb-free cats caused by unscavenged NO, but this mechanism does not play a major role in FC-related CBF increases in the rest of the cerebral circulation. PMID:9362271

Wagner, B P; Stingele, R; Williams, M A; Wilson, D A; Traystman, R J; Hanley, D F

1997-10-01

104

Viscoelastic wormlike micelles in mixed nonionic fluorocarbon surfactants and structural transition induced by oils.  

PubMed

Formation and rheological behavior of viscoelastic wormlike micelles in an aqueous solution of a mixed system of nonionic fluorocarbon surfactants, perfluoroalkyl sulfonamide ethoxylate, C8F17SO2N(C3H7)(CH2CH2O)nH (abbreviated as C8F17EOn, n=20 and 3), was studied. A partial ternary phase diagram of water/C8F17EO20/C8F17EO3 was constructed at 25 degrees C by visual inspection through crossed polarizers. In the water/surfactant binary system, C8F17EO20 forms an isotropic micellar solution over a wide concentration range (approximately 80 wt %). The micellar solution of the C8F17EO20 can solubilize a significant amount of C8F17EO3, and the solubility increases with increasing C8F17EO20 concentration. With successive addition of C8F17EO3 to the aqueous C8F17EO20 solution, viscosity increases rapidly, and a viscoelastic solution is formed. The viscosity of the viscous sample was approximately 5th order of magnitude of pure water. The viscoelastic solution follows the Maxwell model typical of wormlike micelles at low-frequency region. With further addition of C8F17EO3 the viscosity decreases, and phase separation occurs. Addition of perfluoropolyether oil, (C3F6O)nCOOH, to the viscoelastic solution decreases the viscosity monotonically until phase separation. On the other hand, when perfluorodecalin oil, C10F18, is added, viscosity first decreases and attains a limiting value before excess oil phase separates out. The viscosity decrease in water/surfactant/oil systems is possibly caused by the microstructural transition in the network structure. Small-angle X-ray scattering (SAXS) measurements were performed to complement the rheological data. It has been found that the C8F17EO3 induces one-dimensional growth to the C8F17EO20 micelles. On the other hand, when (C3F6O)nCOOH is added, wormlike-sphere type transition is more likely to occur. PMID:19193166

Sharma, Suraj Chandra; Shrestha, Rekha Goswami; Shrestha, Lok Kumar; Aramaki, Kenji

2009-02-12

105

Phase behavior, rheological property, and transmutation of vesicles in fluorocarbon and hydrocarbon surfactant mixtures.  

PubMed

We present a detailed study of a salt-free cationic/anionic (catanionic) surfactant system where a strongly alkaline cationic surfactant (tetradecyltrimethylammonium hydroxide, TTAOH) was mixed with a single-chain fluorocarbon acid (nonadecafluorodecanoic acid, NFDA) and a hyperbranched hydrocarbon acid [di-(2-ethylhexyl)phosphoric acid, DEHPA] in water. Typically the concentration of TTAOH is fixed while the total concentration and mixing molar ratio of NFDA and DEHPA is varied. In the absence of DEHPA and at a TTAOH concentration of 80 mmol·L(-1), an isotropic L(1) phase, an L(1)/L(?) two-phase region, and a single L(?) phase were observed successively with increasing mixing molar ratio of NFDA to TTAOH (n(NFDA)/n(TTAOH)). In the NFDA-rich region (n(NFDA)/n(TTAOH) > 1), a small amount of excess NFDA can be solubilized into the L(?) phase while a large excess of NFDA eventually leads to phase separation. When NFDA is replaced gradually by DEHPA, the mixed system of TTAOH/NFDA/DEHPA/H(2)O follows the same phase sequence as that of the TTAOH/NFDA/H(2)O system and the phase boundaries remain almost unchanged. However, the viscoelasticity of the samples in the single L(?) phase region becomes higher at the same total surfactant concentration as characterized by rheological measurements. Cryo-transmission electron microscopic (cryo-TEM) observations revealed a microstructural evolution from unilamellar vesicles to multilamellar ones and finally to gaint onions. The size of the vesicle and number of lamella can be controlled by adjusting the molar ratio of NFDA to DEHPA. The dynamic properties of the vesicular solutions have also been investigated. It is found that the yield stress and the storage modulus are time-dependent after a static mixing process between the two different types of vesicle solutions, indicating the occurrence of a dynamic fusion between the two types of vesicles. The microenvironmental changes induced by aggregate transitions were probed by (19)F NMR as well as (31)P NMR measurements. Upon replacement of NFDA by DEHPA, the signal from the (19)F atoms adjacent to the hydrophilic headgroup disappears and that from the (19)F atoms on the main chain becomes sharper. This could be interpreted as an increase of microfluidity in the mixed vesicle bilayers at higher content of DEHPA, whose alkyl chains are expected to have a lower chain melting point. Our results provide basic knowledge on vesicle formation and their structural evolution in salt-free catanionic surfactant systems containing mixed ion pairs, which may contribute to a deeper understanding of the rules governing the formation and properties of surfactant self-assembly. PMID:22646993

Yuan, Zaiwu; Qin, Menghua; Chen, Xiushan; Liu, Changcheng; Li, Hongguang; Hao, Jingcheng

2012-06-26

106

A model for Si, SiCH, SiO{sub 2}, SiOCH, and porous SiOCH etch rate calculation in inductively coupled fluorocarbon plasma with a pulsed bias: Importance of the fluorocarbon layer  

SciTech Connect

In a previous paper we showed that selective etching of porous SiOCH with respect to SiO{sub 2} and SiCH is clearly enhanced when using a pulsed bias in inductively coupled fluorocarbon plasma. To understand this pulsed process, a model for etch rate calculation is developed in the present paper. This model explains the etching/deposition threshold shift toward higher bias voltage in pulsed conditions. Rather good confidence is obtained with experimental SiO{sub 2}, Si, SiOCH and SiCH etch rates. Porous SiOCH etching is found to behave slightly differently compared to SiO{sub 2} or SiCH; its chemical etching is assumed to occur even during the beginning of off period. This point could explain why good selectivities between porous SiOCH and SiO{sub 2} and SiCH are obtained.

Raballand, V.; Cartry, G.; Cardinaud, C. [Institut des materiaux Jean Rouxel (IMN), Universite de Nantes-CNRS, BP 32229, 44322 Nantes (France)

2007-09-15

107

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

NASA Astrophysics Data System (ADS)

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.

Szymczyk, Katarzyna

2014-03-01

108

Fluorocarbon chain end-capped poly(carbonate urethane)s as biomaterials: blood compatibility and chemical stability assessments.  

PubMed

Previous work has shown the synthesis of fluorocarbon chain (CF(3)(CF(2))(6)CH(2)O-) end-capped poly(carbonate urethane)s (FPCUs) and confirmed the presence of a novel bilayered surface structure in FPCUs, that is, the top fluorocarbon and subsurface hard segment layers (Xie et al., J Biomed Mater Res Part A 2008; 84:30-43). In this work, the effects of such surface structure on blood compatibility were investigated using hemolytic test and platelet adhesion analysis. The chemical stability of the polymers was also determined by Zhao's glass wool-H(2)O(2)/CoCl(2) test and phosphate-buffered saline (PBS, pH = 3.1-3.3) treatment. One of the FPCUs, FPCU-A, and two control materials, a poly(ether urethane) (PEU) and a poly(carbonate urethane) (PCU), were investigated. No significant difference in hemolytic indices was observed among the three materials, whereas the adherent density and deformation of platelets were much lower on FPCU-A compared with on PCU and PEU. Severe surface cracking and surface buckling developed in prestressed PEU and PCU films after H(2)O(2)/CoCl(2) treatment, respectively, whereas smooth surface was observed for the FPCU-A. PBS incubation resulted in parallel ridge-like morphology in PCU whereas PEU and FPCU-A retained their smooth surfaces. Under relatively high stress conditions, all the materials developed well-oriented strip-like surface patterns. Results from ATR-FTIR spectra revealed a surface oxidation mechanism as described in literature. However, observations of universal decrease of molecular weights under stress conditions further suggested the presence of another bulk stress oxidation mechanism. Regardless the degradation mechanisms involved, the unique bilayered surface structure really improved the blood compatibility and chemical stability of FPCU-A, indicating that further in vivo investigations are worthwhile. PMID:18837450

Xie, Xingyi; Wang, Ruifang; Li, Jiehua; Luo, Liang; Wen, Da; Zhong, Yinping; Zhao, Changsheng

2009-04-01

109

Reverse water-in-fluorocarbon emulsions for use in pressurized metered-dose inhalers containing hydrofluoroalkane propellants.  

PubMed

Pulmonary administration of drugs has demonstrated numerous advantages in the treatment of pulmonary diseases due to direct targeting to the respiratory tract. It enables avoiding the first pass effect, reduces the amount of drugs administered, targets drugs to specific sites and reduces their side effects. Reverse water-in-fluorocarbon (FC) emulsions are potential drug delivery systems for pulmonary administration using pressurized metered-dose inhalers (pMDI). The external phase of these emulsions consists of perfluorooctyl bromide (PFOB, perflubron), whereas their internal phase contains the drugs solubilized or dispersed in water. These emulsions are stabilized by a perfluoroalkylated dimorpholinophosphate (F8H11DMP), i.e. a fluorinated surfactant. This study demonstrates the possibility of delivering a reverse fluorocarbon emulsion via the pulmonary route using a CFC-free pMDI. Two hydrofluoroalkanes (HFAs) (Solkane(R) 134a and Solkane(R) 227) were used as propellants, and various solution (or emulsion)/propellant ratios (1/3, 1/2, 2/3, 1/1, 3/2, 3/1 v/v) were investigated. The insolubility of water (with or without the fluorinated surfactant F8H11DMP) in both HFA 227 and HFA 134a was demonstrated. PFOB and the reverse emulsion were totally soluble or dispersible in all proportions in both propellants. This study demonstrated also that the reverse FC emulsion can be successfully used to deliver caffeine in a homogeneous and reproducible way. The mean diameter of the emulsion water droplets in the pressured canister was investigated immediately after packaging and after 1 week of storage at room temperature. Best results were obtained with emulsion/propellant ratios comprised between 2/3 and 3/2, and with HFA 227 as propellant. PMID:11996829

Butz, N; Porté, C; Courrier, H; Krafft, M P; Vandamme, Th F

2002-05-15

110

Tube Radial Distribution Phenomenon with a Two-phase Separation Solution of a Fluorocarbon and Hydrocarbon Organic Solvent Mixture in a Capillary Tube and Metal Compounds Separation.  

PubMed

A fluorocarbon and hydrocarbon organic solvent mixture is known as a temperature-induced phase-separation solution. When a mixed solution of tetradecafluorohexane as a fluorocarbon organic solvent and hexane as a hydrocarbon organic solvent (e.g., 71:29 volume ratio) was delivered in a capillary tube that was controlled at 10°C, the tube radial distribution phenomenon (TRDP) of the solvents was clearly observed through fluorescence images of the dye, perylene, dissolved in the mixed solution. The homogeneous mixed solution (single phase) changed to a heterogeneous solution (two phases) with inner tetradecafluorohexane and outer hexane phases in the tube under laminar flow conditions, generating the dynamic liquid-liquid interface. We also tried to apply TRDP to a separation technique for metal compounds. A model analyte mixture, copper(II) and hematin, was separated through the capillary tube, and detected with a chemiluminescence detector in this order within 4 min. PMID:24919675

Kitaguchi, Koichi; Hanamura, Naoya; Murata, Masaharu; Hashimoto, Masahiko; Tsukagoshi, Kazuhiko

2014-01-01

111

Integrated feature scale modeling of plasma processing of porous and solid SiO2. II. Residual fluorocarbon polymer stripping and barrier layer deposition  

Microsoft Academic Search

The adoption of low dielectric constant materials as inter-level dielectrics in microelectronics fabrication will ultimately depend on process integration. Porous SiO2 (PS) is one candidate material. Cleaning of residual polymer from trenches following etching using fluorocarbon plasmas and the deposition of a continuous barrier layer are critical processes for integration of PS as inter-level dielectrics. To investigate these issues, reactions

Arvind Sankaran; Mark J. Kushner

2004-01-01

112

Integrated feature scale modeling of plasma processing of porous and solid SiO2. II. Residual fluorocarbon polymer stripping and barrier layer deposition  

NASA Astrophysics Data System (ADS)

The adoption of low dielectric constant materials as inter-level dielectrics in microelectronics fabrication will ultimately depend on process integration. Porous SiO2 (PS) is one candidate material. Cleaning of residual polymer from trenches following etching using fluorocarbon plasmas and the deposition of a continuous barrier layer are critical processes for integration of PS as inter-level dielectrics. To investigate these issues, reactions mechanisms for plasma stripping of fluorocarbon polymer using oxygen containing plasmas and deposition of metal barrier coatings into PS trenches were developed, and incorporated into a feature profile model. The reaction mechanism was validated by comparison to experiments for blanket plasma etching of polytetrafluoroethylene using Ar-O2 chemistries. Plasma stripping of fluorocarbon polymers from solid SiO2 (SS) trenches was found to be less efficient at higher aspect ratios. Stripping was also less efficient from PS trenches having large average pore radius and high interconnectivity. Cu ionized metal physical vapor deposition was investigated as a surrogate for barrier coating in SS and PS trenches. Compared to SS, thin film deposition was less conformal for PS having closed pore networks. Thicker films were required for interconnected PS to avoid pin-hole formation. .

Sankaran, Arvind; Kushner, Mark J.

2004-07-01

113

Fundamental Adsorption Properties for Low Molecular Weight Alcohols in Fluorocarbon Thin Films Deposited onto Quartz Crystal Microbalance Electrode by an R.F. Sputtering and Spin Coating  

NASA Astrophysics Data System (ADS)

Highly sensitive detection methods for volatile organic compounds (VOCs) are needed in working environment handling the VOCs. The use of a quartz crystal microbalance (QCM) is one such method, and many studies have been carried out on the deposition of metallic, inorganic and organic thin films onto QCM surfaces for use as sensors. In this paper, we report on adsorption properties of fluorocarbon thin films deposited onto the QCM electrode by an r.f. sputtering and spin coating for low molecular weight VOCs such as aliphatic alcohols and acetone. Adsorption mass of these VOC molecules in the fluorocarbon thin film deposited by the r.f. sputtering were much higher than that in the thin film deposited by the spin coating. It is known that molecular structures of fluorocarbon thin films sputtered with a Poly(tetrafluoroethylene) (PTFE) target were quite different from pristine PTFE. It is considered that this is one of reasons why the adsorption mass in the thin film deposited by the r.f. sputtering was higher than that in the thin film deposited by the spin coating.

Iwamori, Satoru; Miyamoto, Takaaki; Ikeda, Yuki; Ohnishi, Yasutaka; Noda, Kazutoshi

114

Plasma etching of dielectric materials using inductively and capacitively coupled fluorocarbon discharges: Mechanistic studies of the surface chemistry  

NASA Astrophysics Data System (ADS)

Fluorocarbon (FC) plasmas are commonly used for dielectric materials etching. Our initial work was performed using an inductively coupled plasma (ICP) system to produce FC discharges. We first examined the effect of CO addition to C4F8 or C4F8/Ar plasmas for selective etching of organosilicate glass (OSG), which is a typical low k (LK) material over etch stop layers. The chemical activity of CO when added to either C4F8 Or C4F8/80% Ar can be understood in terms of the CO dissociation energy threshold relative to energies of inelastic electron collision processes of the dominant feedgas component. We also studied the plasma etching behavior of 193 nm and 248 nm photoresist in FC discharges used for dielectric etching. We showed that ion-enhanced selective volatilization of carbonyl groups of the 193 nm photoresist polymer backbone which is absent for the 248 nm material, along with modulation of the ion-interaction with the photoresist material by fluorocarbon surface passivation, may be responsible for the introduction of pronounced surface roughness of 193 nm photoresists. Current industrial efforts are aimed primarily at capacitively coupled plasma (CCP) systems. A home-built dual frequency CCP reactor was used to investigate additional aspects of dielectric materials plasma etching. We designed a gap structure to simulate sidewall surface processes occurring during high aspect ratio trench etching. In particular, we showed that the FC film deposition rates measured using the gap structure qualitatively correlate with the trench sidewall angles produced in LK dielectrics in both C 4F8/Ar and CF4/H2 based gas chemistries: The lower the FC deposition rate on the sidewall, the more vertical the trench sidewall. This approach was used to study surface chemistry aspects of FC film deposition with and without ion bombardment. For the gap structure film deposition takes place without ion bombardment and we observed a novel FC film growth phenomenon in pure C4F8 plasmas at high pressure: Two distinct chemical surface portions were shown to exist simultaneously, one consisting primarily of C-F2 and C-F3 bonding, and the other of C-C/C-H bonding. An explanation consistent with all of our data is localized CF2 attachment to growing FC chains.

Ling, Li

115

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

PubMed

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

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

2013-03-01

116

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

PubMed

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

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

2011-07-01

117

Etch Challenges Brought by the Metal Hardmask Approach for Advanced Contact Patterning with Fluorocarbon-based Plasma  

NASA Astrophysics Data System (ADS)

In order to overcome patterning challenges brought by dimensional scaling and aggressive pitches, extreme ultra-violet (EUV) lithography has been recently pushed forward as a possible solution for IC manufacturing, allowing extended exposure latitude at sub-50nm dimensions. This work address the technological solutions used for contact holes patterning by means of EUV lithography. A metal hard-mask (MHM) approach has been selected, in order to combine the etching of high-aspect ratio features with thin EUV photoresist. The pre-metal dielectric stack covering the active fins was composed of 15nm Si3N4 as an etch-stop liner, covered by 240nm SiO2. The MHM was made of a 30nm TiN film on top of which was spun 20nm of organic underlayer and 100nm of EUV photoresist. This presentation will describe in details the various plasma processing issues and challenges met with this patterning strategy, for down to ˜50nm contact hole sizes: SiO2:TiN and SiO2:Si3N4 selectivities by means of fluorocarbon-based chemistries; loading effects; profile and mask undercut control with CCP plasma; residue cleaning.

de Marneffe, Jean-Francois; Goossens, Danny; Shamiryan, Denis; Struyf, Herbert; Boullart, Werner

2008-10-01

118

Etching mechanisms of Si and SiO{sub 2} in inductively coupled fluorocarbon plasmas: Correlation between plasma species and surface etching  

SciTech Connect

Etching mechanisms of silicon and silicon oxide in a fluorocarbon environment are studied in an ICP reactor. Optimization of the process for deep etching of SiO{sub 2} with a Si mask has been discussed in a previous article. In this article, adequate plasma conditions are chosen both (a) to allow separation of parametric variables and (b) to get appreciable variation of the different plasma and surface experimental results versus parameters. Hence, pressure, source power, ion energy, and subsequently ion flux are kept constant. The influences of the gas composition and the residence time (varying gas flow rate) are studied. We show that silicon etching depends both on the atomic fluorine concentration in the plasma and of the fluorocarbon blocking layer at the surface. We pay particular attention to the formation of the fluorocarbon overlayer. We establish that the thickness of this layer is linked to the plasma species through the (C+H)/F ratio, calculated from the radical densities in the gas, taking into account the etching-deposition competition. Concerning oxide etching in the so-called sputtering regime, we show that the overlayer detected by x-ray photoelectron spectroscopy does not control the etching mechanism and seems to be an interaction layer between plasma and oxide rather than a blocking layer. We also establish a linear relation between oxide etch yield and the average F/C ratio calculated from the ion densities indicating that the radical species are not a limiting factor in the oxide etching mechanism. Finally, from these results for oxide and silicon etching, a correlation between plasma species and the evolution of the etch rates versus ion energy is done by varying gas composition and residence time.

Gaboriau, F.; Fernandez-Peignon, M-C.; Cartry, G.; Cardinaud, Ch. [Laboratoire des Plasmas et des Couches Minces, IMN-CNRS-Universite de Nantes, 2 rue de la Houssiniere, BP 32229, 44322 Nantes Cedex 3, (France)

2005-03-01

119

Amorphous fluorocarbon polymer (aC:F) films obtained by plasma enhanced chemical vapor deposition from perfluoro-octane (C8F18) vapor I: Deposition, morphology, structural and chemical properties  

Microsoft Academic Search

The method of obtaining amorphous fluorocarbon polymer (a-C:F) films by plasma enhanced chemical vapor deposition in a capacitively coupled, 13.56 MHz reactor, from a new monomer, namely perfluoro-octane (C8F18) vapor, is presented. For monomer pressure ranging from 0.2 to 1 Torr and input power density from 0.15 to 0.85 W\\/cm3, the maximum deposition rate reached 300 nm\\/min, while 10% monomer

Costel Biloiu; Ioana Arabela Biloiu; Yosuke Sakai; Yoshiyuki Suda; Akitsugu Ohta

2004-01-01

120

Amorphous fluorocarbon polymer (aC:F) films obtained by plasma enhanced chemical vapor deposition from perfluoro-octane (C8F18) vapor. II. Dielectric and insulating properties  

Microsoft Academic Search

Amorphous fluorocarbon polymer films (a-C:F) have been grown by plasma enhanced chemical vapor deposition from a new precursor, namely perfluoro-octane (C8F18) vapor. The dielectric and insulating properties of the films have been assessed by means of capacitance-voltage and current-voltage characteristics, breakdown voltage measurements, scanning electron microscopy, and ellipsometric analyses. In the investigated frequency range, 120 Hz-1 MHz, the films have

Costel Biloiu; Ioana Arabela Biloiu; Yosuke Sakai; Hirotake Sugawara; Akitsugu Ohta

2004-01-01

121

Kinetics of the reactions involving CF 2 and CF in a pure tetrafluoromethane plasma: II. Production and loss of CF 2 and CF in the processes of fluorocarbon polymerization  

Microsoft Academic Search

Mechanisms for the production and loss of CF2 and CF radicals in a glow discharge in pure CF4 are investigated by the time-resolved laser-induced fluorescence method. The fluorocarbon polymerization processes are shown\\u000a to contribute significantly to the production of radicals both in the plasma volume and on the surface of the discharge tube.\\u000a The effective frequencies of both the volume

V. V. Ivanov; K. S. Klopovskii; D. V. Lopaev; O. V. Proshina; A. T. Rakhimov; T. V. Rakhimova; G. B. Rulev

2002-01-01

122

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

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.

Harrison, R.G.

1993-01-01

123

Enhancement of the antitumor effect of glucose oxidase by combined administration of hydrogen peroxide decomposition inhibitors together with an oxygenated fluorocarbon.  

PubMed

Glucose oxidase (GO) catalyzes the conversion of beta-D-glucose and molecular oxygen to D-glucono-delta-lactone and H2O2. H2O2 produced by GO was effective in preventing tumor growth in mice bearing not only ascites tumor but also solid tumor. The effect of GO was enhanced by the combined administration of catalase inhibitors such as 3-aminotriazole, hydroxylamine and sodium azide or the GSH synthesis inhibitor buthionine-(S,R)-sulfoximine in vivo. The cytolytic activity of GO against T-24 cultured cells in vitro was also enhanced by addition of these inhibitors together with GO. In the peritoneal cavity of mice the antitumor effect of GO seemed to be dependent on the amount of oxygen released from oxygenated fluorocarbon-43 (FC-O2), an oxygen-supplying substance. Furthermore, the combined administration of H2O2-decomposing enzyme inhibitors and FC-O2 synergistically enhanced the antitumor effect of GO. These results suggest that GO is suitable for antitumor chemotherapy and that the use of inhibitors of H2O2-decomposing enzymes and FC-O2 potentiated the GO therapy. PMID:1910030

Higuchi, Y; Shoin, S; Matsukawa, S

1991-08-01

124

Synthesis of transparent fluorocarbon elastomers: effect of crosslinker type and electron beam irradiation level on physical and mechanical behavior. [Elastomers - Viton GLT-copolymer of vinylidene fluoride, perfluoro(methyl vinyl ether) and tetrafluoroethylene; triallyl isocyanurate  

SciTech Connect

Saturated fluorocarbon elastomers are very resistant to chemical reactions, including those of a crosslinking nature. In order to study proper methods of preparing these materials, Viton GLT was mixed with various levels of trimethylol propane trimethacrylate, TMPTM, and triallyl isocyanurate, Diak No. 7. After molding, the materials were subjected to electron beam irradiation. The glass transition, rubbery modulus, viscoelastic behavior, and equilibrium swelling were used to characterize the materials as a function of crosslinker and irradiation level. In general, the modulus and gel fraction increased with both crosslinker content and irradiation level. Mixtures of both crosslinking monomers produced an unexpected synergism, yielding higher tensile strength, and earlier onset of gelation.

Kaiser, R.J.; Miller, G.A.; Thomas, D.A.; Sperling, L.H.

1982-03-01

125

Studies of the effects of fluorocarbon deposition and etching on silicon and silicon dioxide etching processes using methyl trifluoride in an inductively coupled plasma reactor, and the development of a reactive ion beam system for the study of plasma-surface interaction mechanisms  

NASA Astrophysics Data System (ADS)

Plasma etching of silicon and silicon dioxide using CHF3 in an Inductively Coupled Plasma (ICP) tool, has been studied in detail. Fluorocarbon deposition on these material surfaces during processing is shown to regulate the etching process. XPS analysis of surface residues on etched silicon dioxide shows that for low bias powers, oxide etching takes place within the presence of a steady state fluorocarbon film with a thickness of less than one nanometer. This film suppresses the oxide etch rate, by interfering with the direct interaction between ion species and the oxide substrate. Surface analysis of deposited fluorocarbon films has shown that the film stoichiometry is a result of a complex combination of several processing parameters. The ion energy flux reduces the fluorination of these films, while the stoichiometry of the reactive neutral component of the plasma primarily determines the stoichiometry of passively deposited (unbiased) films. The fluorocarbon over layer thickness on silicon during silicon etching, is shown to be directly linked to the passively deposited fluorocarbon etch yield which in turn is directly related to the film stoichiometry. A direct correlation is found to exist between the silicon etch yield and the passively deposited fluorocarbon etch yield. Thus, the silicon etch process is observed to be regulated by the deposition and etch behavior of the fluorocarbon film. The selectivity of oxide over silicon exhibits high selectivity ratios for all pressure conditions at high inductive power. The highest selectivity of 34 has been achieved for an intermediate pressure of 10 mTorr. A suggested mechanism has been presented involving a complex tradeoff between film stoichiometry and ion enhanced diffusion of fluorine through the fluorocarbon over layer. Finally, a reactive ion beam system is presented as a future tool for the investigation of plasma-surface interactions. The development of an ion beam source capable of producing mass selected reactive ion species is outlined including preliminary results of ion beam characterization and ion sputter yields for Ar+ incident on silicon dioxide. A technique for accurate etch yield measurements is presented involving the use of a quartz crystal microbalance as the sample substrate.

Rueger, Neal R.

126

Amorphous fluorocarbon polymer (a-C:F) films obtained by plasma enhanced chemical vapor deposition from perfluoro-octane (C8F18) vapor. II. Dielectric and insulating properties  

NASA Astrophysics Data System (ADS)

Amorphous fluorocarbon polymer films (a-C:F) have been grown by plasma enhanced chemical vapor deposition from a new precursor, namely perfluoro-octane (C8F18) vapor. The dielectric and insulating properties of the films have been assessed by means of capacitance-voltage and current-voltage characteristics, breakdown voltage measurements, scanning electron microscopy, and ellipsometric analyses. In the investigated frequency range, 120 Hz-1 MHz, the films have a low dielectric constant (~2.4) and a low dielectric loss (<=3×10-2). The electrical conduction mechanism is ohmic in the weak electric field regime, with a bulk resistivity of 4×1015 ? cm, and a trap modulated space charge limited conduction in the strong electric field regime. For a film thickness between 1 and 12 ?m, the dielectric strength varies with film thickness according to EB~h-0.53. For a film thickness of 1 ?m the film dielectric strength was 2.7 MV/cm while for 12 ?m it decreased to 0.9 MV/cm. Measurements of the breakdown voltage in nitrogen gas in the low pressure regime between a-C:F coated cathode and copper anode showed an enhancement of the breakdown voltage by a factor of 2.5 with respect to the case of copper-copper electrodes. .

Biloiu, Costel; Biloiu, Ioana Arabela; Sakai, Yosuke; Sugawara, Hirotake; Ohta, Akitsugu

2004-07-01

127

Amorphous fluorocarbon polymer (a-C:F) films obtained by plasma enhanced chemical vapor deposition from perfluoro-octane (C8F18) vapor I: Deposition, morphology, structural and chemical properties  

NASA Astrophysics Data System (ADS)

The method of obtaining amorphous fluorocarbon polymer (a-C:F) films by plasma enhanced chemical vapor deposition in a capacitively coupled, 13.56 MHz reactor, from a new monomer, namely perfluoro-octane (C8F18) vapor, is presented. For monomer pressure ranging from 0.2 to 1 Torr and input power density from 0.15 to 0.85 W/cm3, the maximum deposition rate reached 300 nm/min, while 10% monomer dilution with argon led to a deposition rate of 200 nm/min. The film surface and bulk morphologies, chemical and structural compositions were investigated using scanning electron microscopy, x-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. It was revealed that the films have a dense and compact structure. The fluorine to carbon ratio (F/C) of the films was between 1.57 and 1.75, and the degree of cross-linking was between 55% and 58%. The relative amount of perfluoroalkyl (CF2) groups in the films was 29%. The FTIR spectra showed absorption bands corresponding to the different vibrational modes of CF, CF2, and CF3 moieties. .

Biloiu, Costel; Biloiu, Ioana Arabela; Sakai, Yosuke; Suda, Yoshiyuki; Ohta, Akitsugu

2004-01-01

128

Nonclassical gasdynamic region of selected fluorocarbons  

NASA Astrophysics Data System (ADS)

The nonclassical gasdynamic region of fluorinated substances belonging to the PP, FC, and E series is investigated using different thermodynamic models of increasing complexity. Thermodynamic models range from the simple van der Waals equation of state to the more complex Martin-Hou model and include the Redlich-Kwong, Clausius-II, Soave-Redlich-Kwong, and Peng-Robinson equations, under both the polytropic (constant isochoric specific heat in the dilute gas limit) and nonpolytropic approximations. The possibility of observing nonclassical gasdynamic behavior for a given fluid is confirmed to increase with the molecular weight of the substance times the specific heat at constant volume in the dilute gas limit and at the critical temperature, but to be almost insensitive to the nonpolytropic behavior of the fluid; the dependence on the compressibility at the critical point is also weak. A strong dependence on the acentric factor of the substance is revealed, which points to fluids made of nonpolar molecules with nearly spheroidal shapes as the most favorable to exhibit nonclassical gasdynamic behavior. In this respect, the fluorinated cyclic compounds of the PP series are singled out as the most promising candidates for the experimental verification of the existence of nonclassical phenomena in the vapor phase and for nonclassical gasdynamic applications.

Guardone, A.; Argrow, B. M.

2005-11-01

129

Effects of fluorocarbons on biological systems  

Microsoft Academic Search

The halogenated hydrocarbons, in particular, the fluoroalkane gases of Freons (generic name, halons), are widely used today in various industrial and household applications because they are felt to be relatively non-toxic. The effects of Freon-11 (trichlorofluoromethan), Freon-21 (dichlorofluoromethane), Freon-22 (monochlorodifluoromethane), and Halothane (2-bromo-2-chloro-1,1,1-trifluoroethane) were tested on several different biological systems including eight species of bacteria, two species of plants, and

J. Healy; R. T. S. Lee; D. Perrotta; O. W. Van Auken

1974-01-01

130

21 CFR 177.1380 - Fluorocarbon resins.  

Code of Federal Regulations, 2013 CFR

... FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components of Single...contact with food. (3) In accordance with current good manufacturing practice, those food-contact articles intended for...

2013-04-01

131

Flammability limits of fuel/fluorocarbon azeotropes  

SciTech Connect

Both Dehn and Thorne have intimated that flash point (FP) measurements could be used to define the gas-phase flammability limits of fire and retardant vapor mixtures above the surface of heated retardant containing flammable liquids. However, it was found that ignitable mixtures exist above the liquid surface, where the concentration of the agent in the fluid is well beyond the limiting concentrating for inerting of alcohol fires. Clearly this anomaly results from diffusion competition of air and liquid vapor mixture at the position of the ignitor, as influenced by the design of the experimental apparatus. The authors are skeptical about the need or worth of attempting to define flammability limits using FP data, especially since unknown variables control the response. More important is to define the concentration of liquid phase retardant that will affect gas phase inerting. Thus, it is necessary to continue practical testing of retardant-containing liquids for their effectiveness in mitigating possible accidents, e.g., the next phase of this work will assess the effectiveness of halocarbons to inert high-pressure alcohol/agent leaks impinging on both electrical and flame ignition sources.

Alvares, N.J.; Hammond, P.R.; Foote, K.; Ford, H.W. Jr.

1981-02-10

132

Photoluminescence of silicone oil treated by fluorocarbon plasma  

NASA Astrophysics Data System (ADS)

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 Si—C bond, the carbon-related defects and the oxygen vacancies. It was suggested that the light emitting at 554 nm was related to the Si—C bond and the carbon-related defects, while the pink emission at 415 nm was related to the oxygen vacancies.

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

133

Total cross section of electron scattering by fluorocarbon molecules  

NASA Astrophysics Data System (ADS)

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.

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

2008-12-01

134

Synthesis of Structurally Unusual Fluorocarbons by Direct Fluorination.  

National Technical Information Service (NTIS)

The reaction of elemental fluorine with structurally unusual hydrocarbon starting materials has been carefully controlled sot that structurally analogous perfluorocarbons have been successfully obtained. The syntheses by direct fluorination of perfluorone...

R. J. Lagow N. J. Maraschin B. D. Catsikis L. H. Davis G. Jarvinen

1974-01-01

135

Piezoelectricity and dynamic characteristics of laminated fluorocarbon films  

Microsoft Academic Search

The piezoelectrets made of porous polytetrafluoroethylene (PTFE) and nonporous fluoroethylenepropylene (FEP) layers are prepared by using a hot-pressing method. The dependence of the quasi-static piezoelectric d33-coefficients of such films on the grid voltage during the corona charging is investigated. The thermal stability of d33-coefficients for the films is characterized by the isothermal method. The Young's Modulus and dynamic d33-coefficient are

Xiaoqing Zhang; Jinfeng Huang; Xuewen Wang; Zhongfu Xia

2010-01-01

136

Thermal Conductivity of Nonazeotropic Gaseous Mixtures of Fluorocarbon Refrigerants  

NASA Astrophysics Data System (ADS)

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%.

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

137

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

NASA Astrophysics Data System (ADS)

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.

Maeno, Kazuo; Udagawa, Shinsuke; Toyada, Kazuhiro

2005-03-01

138

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

SciTech Connect

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.

Shuman, Nicholas S.; Miller, Thomas M.; Viggiano, Albert A., E-mail: afrl.rvborgmailbox@kirtland.af.mil [Air Force Research Laboratory, Space Vehicle Directorate, Kirtland Air Force Base, New Mexico 87117 (United States)

2013-11-14

139

Evolution of Roughness and Wavelength Selection during Fluorocarbon Plasma Etching of Nanoporous Silica  

NASA Astrophysics Data System (ADS)

Nanoporous silica is a technologically appealing candidate as a low-k dielectric material for high speed nano device applications. A crucial issue during plasma pattern transferring processes is the stability of the plasma/NPS interface. Induced surface/interface roughness may ultimately limit the minimum feature sizes attainable in devices using this material. Our results show a monotonic increase with porosity in the roughening rate, and pronounced disagreement with the predictions of simple models based upon self-affine behavior. In addition we find direct evidence for spontaneous pattern formation during etching.

Kwon, Taesoon; Kan, Hung-Chih; Hua, Xuefeng; Oehrlein, Gottlieb; Phaneuf, Ray

2006-03-01

140

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

SciTech Connect

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)

Bates, R. [Dept. of Physics and Astronomy, Univ. of Glasgow, G12 8QQ (United Kingdom); Battistin, M. [CERN, 1211 Geneva 23 (Switzerland); Berry, S.; Bitadze, A. [Dept. of Physics and Astronomy, Univ. of Glasgow, G12 8QQ (United Kingdom); Bonneau, P. [CERN, 1211 Geneva 23 (Switzerland); Bousson, N. [Centre de Physique des Particules de Marseille, 163 Avenue de Luminy, 13288 Marseille Cedex 09 (France); Boyd, G. [Dept. of Physics and Astronomy, Univ. of Oklahoma, Norman, OK 73019 (United States); Botelho-Direito, J.; DiGirolamo, B. [CERN, 1211 Geneva 23 (Switzerland); Doubek, M. [Czech Technical Univ., Technicka 4, 166 07 Prague 6 (Czech Republic); Egorov, K. [Physics Dept., Indiana Univ., Bloomington, IN 47405 (United States); Godlewski, J. [CERN, 1211 Geneva 23 (Switzerland); Hallewell, G. [Centre de Physique des Particules de Marseille, 163 Avenue de Luminy, 13288 Marseille Cedex 09 (France); Katunin, S. [B.P. Konstantinov Petersburg Nuclear Physics Inst. PNPI, 188300 St. Petersburg (Russian Federation); Mathieu, M.; McMahon, S. [Rutherford Appelton Laboratory - Science and Technology Facilities Council, Chilton, Didcot OX11 OQX (United Kingdom); Nagai, K. [Graduate School of Pure and Applied Sciences, Univ. of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Perez-Rodriguez, E. [CERN, 1211 Geneva 23 (Switzerland); Rozanov, A. [Centre de Physique des Particules de Marseille, 163 Avenue de Luminy, 13288 Marseille Cedex 09 (France); Vacek, V.; Vitek, M. [Czech Technical Univ., Technicka 4, 166 07 Prague 6 (Czech Republic)

2011-07-01

141

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

Code of Federal Regulations, 2011 CFR

...based on the Air-Conditioning and Refrigeration Institute Standard 700-1995. Section...repackaged) for use in new and existing refrigeration and air-conditioning products as...700-1995, 1995, Air-Conditioning and Refrigeration Institute. Appendix C to ARI...

2011-07-01

142

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...

143

Neutral red assay of the cytotoxicity of fluorocarbon-coated polymethylmethacrylate intraocular lenses in vitro.  

PubMed

Polymethylmethacrylate (PMMA) intraocular lenses (IOLs) were coated with Teflon AF, an amorphous, transparent Teflon, to render them highly hydrophobic. Teflon-coated PMMA IOLs were immersed in culture medium for 30 days at 37 degrees C. Four concentrations of the IOL leachables, 2 concentrations of a toxic control (phenol), and complete liquid culture medium (nontoxic control) were incubated for 24 h in a 96-well plate containing confluent L-929 fibroblasts. The cytotoxic effect of each solution on the fibroblasts was quantitatively assessed by measuring the uptake of neutral red by the viable cells. After the extraction of the neutral red using 1% acetic acid-50% ethanol, the optical densities were measured with a microplate reader at 550 nm. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used to analyze the surfaces of the IOLs. Only the optical densities in the wells containing fibroblasts that had been in contact with the phenol solutions were significantly lower than those in the wells incubated with the nontoxic control solution (p < 0.01). There were no signs of surface alteration by SEM, apart from some crystals on the IOLs. The crystals were composed of Na and Cl, as demonstrated by XPS. Aqueous extractables from the Teflon-coated IOLs produced no cytotoxic effects in the neutral red assay used. PMID:10556845

Werner, L; Legeais, J M; Nagel, M D; Renard, G

1999-01-01

144

A low-temperature bonding technique using spin-on fluorocarbon polymers to assemble microsystems  

Microsoft Academic Search

A new low-temperature biochemically compatible polymer bonding process has been successfully developed. The bonding has been characterized for bond strength and chemical resistance. This technique has successfully addressed a major challenge in the development of microfluidic systems from discrete components by enabling the bonding of the components to the microfluidic motherboards at low temperatures and ensuring reliable, leak-proof and chemically

Kwang W. Oh; Arum Han; Shekhar Bhansali; Chong H. Ahn

2002-01-01

145

Synthesis and Biological Screening of Novel Hybrid Fluorocarbon Hydrocarbon Compounds for Use as Artificial Blood Substitutes.  

National Technical Information Service (NTIS)

The goal of this project is to prepare a series of hybrid fluorochemicals of general structure R(f)1 R(f)2 R(f)3CR4, where the R(f)i's are saturated fluoroalkyl groups of formula C(n)F(2n+1), and R4 is an alkyl group C(n)H(2n+1) or related moity containin...

J. Moacanin K. Scherer A. Toronto D. Lawson T. Terranova

1978-01-01

146

Sources of Hydrochlorofluorocarbons, Hydrofluorocarbons, and Fluorocarbons and Their Potential Emissions during the Next Twenty Five Years.  

ERIC Educational Resources Information Center

Examines the potential for the replacement of CFCs for historic uses with substituting technologies. The potential production and emissions of the principal HCFCs and HFCs are calculated for the next 25 years. (LZ)

McCulloch, Archie

1994-01-01

147

Characterization of electron and negative ion densities in fluorocarbon containing inductively driven plasmas  

Microsoft Academic Search

Electron and negative ion densities were measured in inductively coupled discharges containing C4F8. In addition, the identity of the negative ions in C2F6,CHF3, and C4F8 containing discharges was investigated with a photodetachment experiment utilizing a microwave resonant cavity structure. To investigate the influence of surface material, the rf-biased electrode was covered with a silicon wafer or a fused silica (SiO2)

G. A. Hebner; I. C. Abraham

2001-01-01

148

Characterization of electron and negative ion densities in fluorocarbon containing inductively driven plasmas  

Microsoft Academic Search

Electron and negative ion densities were measured in inductively coupled discharges containing C4F8. In addition, the identity of the negative ions in C2F6, CHF3, and C4F8 containing discharges was investigated with a photodetachment experiment utilizing a microwave resonant cavity structure. To investigate the influence of surface material, the rf-biased electrode was covered with a silicon wafer or a fused silica

G. A. Hebner; I. C. Abraham

2001-01-01

149

Detection of chlorodifluoroacetic acid in precipitation: A possible product of fluorocarbon degradation  

SciTech Connect

Chlorodiffluoroacetic acid (CDFA) was detected in rain and snow samples from various regions of Canada. Routine quantitative analysis was performed using an in-situ derivatization technique that allowed for the determination of CDFA by GC-MS of the anilide derivative. Validation of environmental CDFA was provided by strong anionic exchange chromatography and detection by {sup 19}F NMR. CDFA concentrations ranges from <7.1 to 170 ng L{sup {minus}1} among all samples analyzed. Monthly volume-weighted CDFA concentrations ranged from <7.1 to 170 ng L{sup {minus}1} among all samples analyzed. Monthly volume-weighted CDFA concentrations in rain event samples showed a seasonal trend between June and November 1998, peaking in late summer and decreasing in the fall for Guelph and Toronto sites. Preliminary toxicity tests with the aquatic macrophytes Myriophyllum sibiricum and Myriophyllum spicatum suggest that CDFA does not represent a risk of acute toxicity to these aquatic macrophytes at current environmental concentrations. A degradation study suggests that CDFA is recalcitrant to biotic and abiotic degradation relative to dichloroacetic acid (DCA) and may accumulate in the aquatic environment. On the basis of existing experimental data, the authors postulate that CDFA is a degradation product of CFC-113 and, to a lesser extent, HCFC-142b. If CFC-113 is a source, its ozone depletion potential may be lower than previously assumed. Further work is required to identify alternative atmospheric and terrestrial sources of CDFA.

Martin, J.W.; Franklin, J.; Hanson, M.L.; Solomon, K.R.; Mabury, S.A.; Ellis, D.A.; Scott, B.F.; Muri, D.C.G.

2000-01-15

150

Investigation of fluorocarbon blowing agents in insulating polymer foams by 19F NMR imaging.  

PubMed

Currently, there is no reliable and readily accessible technique with which the distribution and diffusion of blowing agents in rigid insulating foams can be detected and monitored. In this paper, we demonstrate that 19F NMR microscopic imaging together with 19F solid-state MAS NMR spectroscopy is ideally suited for such measurements and yield quantitatively reliable information that will be critical to the development and fabrication of optimized insulating materials with alternative blowing agents. Polystyrene (PS) and polyurethane (PU) foam samples were investigated with the objective of determining quantitatively the amount of blowing agents in the gaseous phase and dissolved in the polymer phase, and to determine and monitor the distribution of the blowing agents in aged foams as a function of time and temperature. The concentrations of the gaseous blowing agents in the cells and dissolved in the solid were simultaneously and quantitatively measured by 19F MAS NMR spectroscopy. An unfaced 1-yr-old PS foam filled with CH3CF2Cl has about 13% of total HCFCs dissolved in the solid; while there is about 24% of HCFCs in the solid of a faced 3-mos-old PU foam filled with CH3CCl2F. The data from 19F NMR imaging demonstrate that the distributions of the blowing agents in an aged foam are quite uniform around the center part (2 cm away from any edge) of a foam board; however, a gradient in blowing agent concentration was found as a function of distance from the initial factory cut edge. The effective diffusion coefficients of the blowing agents can be directly calculated from the imaging data. Quantitative diffusion constants and activation barriers were determined. Additionally, a foam treated with a second blowing agent was monitored with chemical shift selective imaging and the diffusion of the second gas into the foam and the out-diffusion of the original gas were determined. PMID:8970101

Fyfe, C A; Mei, Z; Grondey, H

1996-01-01

151

Characterization of Etching of Silicon Dioxide and Photoresist in a Fluorocarbon Plasma.  

National Technical Information Service (NTIS)

Reactive ion etching of silicon dioxide and positive photoresist in CHF3-C2F6-O2-He plasma in a parallel-plate etcher is studied using the response surface experimental design procedure. The experimental results are reproducible within 5%. Analytical expr...

P. C. Karulkar M. A. Wirzbicki

1988-01-01

152

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

SciTech Connect

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.

Not Available

1994-09-01

153

Synthesis of Perfluoro Crown Ethers: A New Class of Cyclic Fluorocarbons.  

National Technical Information Service (NTIS)

The first perfluoro crown ethers, perfluoro-18-crown-6, perfluoro 15-crown-5 and perfluoro 12-crown-4, have been prepared by carefully controlled elemental fluorination. Although they are weaker bases, crown ethers are materials which will have a number o...

W. H. Lin W. I. Bailey R. J. Lagow

1988-01-01

154

Effects of incorporation of fluorocarbon and hydrocarbon surfactants into perfluorosulfonic acid (Nafion) membranes  

SciTech Connect

Perfluorinated ionomer membranes such as Nafion have numerous uses in both industrial chemical practice and in chemical research. Applications include the chloralkali process, H[sub 2]/O[sub 2] fuel cells, biomedical sensing, and other types of chemical sensors based on modified electrodes. Significant permeability improvements can be made to perfluorinated ionomer films by incorporating sulfonated surfactants of suitable size into the membrane microstructure. A variety of 20-[mu]m composite Nafion/surfactant membranes were prepared from DMF casting solutions containing Nafion and the sodium salts of perfluoro-1-butanesulfonic acid (perf-ButSO[sub 3]Na), perfluoro-1-octanesulfonic acid (perf-OctSO[sub 3]Na) and 1-octanesulfonic acid (OctSO[sub 3]Na). The time required for 50% extraction of the surfactants from the membranes into water was 1 min for OctSO[sub 3]Na, 5 min for perf-ButSO[sub 3]Na, and approximately 3 days for perf-OctSO[sub 3]Na. Extraction of perf-OctSO[sub 3]Na into isooctane contacting solutions was not observable over periods of days. For membranes containing surfactants and exchanged with silver(I) ion, 3-fold permeability improvements can be obtained for the separation of 1,5-hexadiene from 1-hexene and n-hexane without any decreases in separation factors. Observed flux improvements are larger than the increase in ion-exchange site density and are attributed to increased mobility of olefins between carrier sites due to the presence of specific surfactants. Results indicate that movement of olefins in Nafion occurs primarily through an interfacial region of the film structure. The ability of a surfactant to improve transport performance is dependent on its ability to partition into the interfacial region. 27 refs., 3 figs., 2 tabs.

Rabago, R.; Noble, R.D.; Koval, C.A. (Univ. of Colorado, Boulder, CO (United States))

1994-07-01

155

An assessment of potential impact of alternative fluorocarbons on tropospheric ozone  

NASA Technical Reports Server (NTRS)

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.

Niki, Hiromi

1990-01-01

156

Surface characterization of plasma deposited nano-structured fluorocarbon coatings for promoting in vitro cell growth  

Microsoft Academic Search

Nano-structured ``teflon-like'' coatings characterized by highly-fluorinated, random, ribbon-shaped, micrometers-long structures were deposited on polyethylenetherephtalate (PET) substrates by plasma enhanced-chemical vapour deposition (PE-CVD) using modulated radiofrequency (RF, 13.56 MHz) glow discharges fed with C2F4 in modulated discharge (MD) and continuous wave (CW) regimes. Surfaces obtained in this way featured identical chemical composition and different roughness in the nanometric scale. Water contact

G. S. Senesi; E. D'Aloia; R. Gristina; P. Favia; R. D'Agostino

2007-01-01

157

Surface characterization of plasma deposited nano-structured fluorocarbon coatings for promoting in vitro cell growth  

NASA Astrophysics Data System (ADS)

Nano-structured "teflon-like" coatings characterized by highly-fluorinated, random, ribbon-shaped, micrometers-long structures were deposited on polyethylenetherephtalate (PET) substrates by plasma enhanced-chemical vapour deposition (PE-CVD) using modulated radiofrequency (RF, 13.56 MHz) glow discharges fed with C 2F 4 in modulated discharge (MD) and continuous wave (CW) regimes. Surfaces obtained in this way featured identical chemical composition and different roughness in the nanometric scale. Water contact angle (WCA) measurements, scanning electron microscopy (SEM) and atomic force microscopy (AFM) were utilized to characterize the surfaces. A positive relationship was shown to exist between the WCA value and the mean nano-structure height and the area root-mean-square (RMS) roughness of coatings. The possibility of obtaining coatings of varying nano-structure height, i.e., roughness, in a nanometric scale represents a promising result for further use of these surfaces as substrates for experiments on cell adhesion, proliferation and growth.

Senesi, G. S.; D'Aloia, E.; Gristina, R.; Favia, P.; d'Agostino, R.

2007-02-01

158

Surface characterization of plasma deposited nano-structured fluorocarbon coatings for promoting in vitro cell growth  

Microsoft Academic Search

Nano-structured “teflon-like” coatings characterized by highly-fluorinated, random, ribbon-shaped, micrometers-long structures were deposited on polyethylenetherephtalate (PET) substrates by plasma enhanced-chemical vapour deposition (PE-CVD) using modulated radiofrequency (RF, 13.56MHz) glow discharges fed with C2F4 in modulated discharge (MD) and continuous wave (CW) regimes. Surfaces obtained in this way featured identical chemical composition and different roughness in the nanometric scale. Water contact angle

G. S. Senesi; E. D’Aloia; R. Gristina; P. Favia; R. d’Agostino

2007-01-01

159

Global warming impacts of CFC alternative technologies: Combining fluorocarbon and COâ effects  

Microsoft Academic Search

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

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

1992-01-01

160

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

Microsoft Academic Search

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

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

1992-01-01

161

Microelectronic cooling by enhanced pool boiling of a dielectric fluorocarbon liquid  

Microsoft Academic Search

An experimental study of boiling heat transfer from a simulated microelectronic component immersed in a stagnant pool of the dielectric Fluorinert (FC-72) is presented. Various enhancement surfaces were attached to an electrically heated copper calorimeter bar having a vertically oriented heat transfer surface area of 12.7 à 12.7 mm². A number of enhancement schemes aimed at a reduction of the

T. M. Anderson; I. Mudawar

1989-01-01

162

Plasma and fluorocarbon-gas free Si dry etching process using a Cat-CVD system  

Microsoft Academic Search

A heated tungsten filament was used to cataltyze the gas phase etching of crystalline silicon with hydrogen at a substrate temperature of 200°C for obtaining plasma and contamination free etching. Etch rates, between 100 and 200 nm\\/min were obtained in a pure hydrogen ambient in the pressure range of 0.01–0.5 Torr. No etching effect was observed in the case of

Akira Izumi; Hidekazu Sato; Shingi Hashioka; Manabu Kudo; Hideki Matsumura

2000-01-01

163

Correlating ion energies and CF{sub 2} surface production during fluorocarbon plasma processing of silicon  

SciTech Connect

Ion energy distribution (IED) measurements are reported for ions in the plasma molecular beam source of the imaging of radicals interacting with surfaces (IRIS) apparatus. The IEDs and relative intensities of nascent ions in C{sub 3}F{sub 8} and C{sub 4}F{sub 8} plasma molecular beams were measured using a Hiden PSM003 mass spectrometer mounted on the IRIS main chamber. The IEDs are complex and multimodal, with mean ion energies ranging from 29 to 92 eV. Integrated IEDs provided relative ion intensities as a function of applied rf power and source pressure. Generally, higher applied rf powers and lower source pressures resulted in increased ion intensities and mean ion energies. Most significantly, a comparison to CF{sub 2} surface interaction measurements previously made in our laboratories reveals that mean ion energies are directly and linearly correlated to CF{sub 2} surface production in these systems.

Martin, Ina T.; Zhou Jie; Fisher, Ellen R. [Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872 (United States)

2006-07-01

164

Correlating ion energies and CF2 surface production during fluorocarbon plasma processing of silicon  

NASA Astrophysics Data System (ADS)

Ion energy distribution (IED) measurements are reported for ions in the plasma molecular beam source of the imaging of radicals interacting with surfaces (IRIS) apparatus. The IEDs and relative intensities of nascent ions in C3F8 and C4F8 plasma molecular beams were measured using a Hiden PSM003 mass spectrometer mounted on the IRIS main chamber. The IEDs are complex and multimodal, with mean ion energies ranging from 29 to 92 eV. Integrated IEDs provided relative ion intensities as a function of applied rf power and source pressure. Generally, higher applied rf powers and lower source pressures resulted in increased ion intensities and mean ion energies. Most significantly, a comparison to CF2 surface interaction measurements previously made in our laboratories reveals that mean ion energies are directly and linearly correlated to CF2 surface production in these systems.

Martin, Ina T.; Zhou, Jie; Fisher, Ellen R.

2006-07-01

165

Fluorocarbon liner protected with chemical resistant masonry solves tough corrosion problem  

SciTech Connect

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.

Heffner, D. [Electro Chemical Engineering and Manufacturing Inc., Emmaus, PA (United States)

1997-02-01

166

Creation of fluorocarbon barriers on surfaces of starch-based products through cold plasma treatment  

Microsoft Academic Search

Two kinds of starch foam trays (starch and aspen-starch foam trays) were produced using a lab model baking machine. Surfaces of the trays were treated with CF4 and SF6 plasma to create fluorine-rich layers on the surfaces, which might show strong water resistance. The plasma parameters, such like RF power, gas pressure and reaction time, were varied to evaluate the

Yousoo Han

2002-01-01

167

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

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

168

Oil-fluorocarbon direct contact heat exchanger for low temperature power generation  

Microsoft Academic Search

In order to demonstrate the feasibility of power generation from medium and low temperature waste heat, geothermal heat, etc, a direct contact heat exchanger was developed. This new heat exchanger is especially excellent in its economies and heat exchange characteristics. To obtain design data for actual applications, a full-scale test was conducted to clarify problems encountered in the basic experiments.

S. Sakaguchi; U. Kuroda

1983-01-01

169

Liquid Breathing: Fluorocarbons in Biological Research. Proceedings from a FOA (Foersvarets Forskningsanstalt) 5 Workshop,  

National Technical Information Service (NTIS)

In 1987 the Naval Medicine Division of the Swedish Defense Research Establishment arranged a one-day workshop with the title Liquid Breathing. Invited speakers presented papers on different aspects of liquid breathing: Introduction to liquid breathing: An...

H. Oernhagen L. Nordin

1988-01-01

170

Giant brainlike aggregates from new fluorocarbon/hydrocarbon hybrid cationic surfactants.  

PubMed

A rapid synthetic procedure in two steps from perfluoroalkylethyl iodide derivatives led to 18 novel ammonium type hybrid surfactants of the general formula: R(F)(CH(2))(2)S(CH(2))(2)N(+)(CH(3))(2)R(H)Br(-) (R(F) = C(4)F(9), C(6)F(13), C(8)F(17); R(H) = C(4)H(9), C(6)H(13), C(8)H(17), C(10)H(21), C(12)H(25), C(14)H(29)). These hybrid surfactants exhibited very low surface tension (from 16 to 25 mN/m) as well as low critical micellar concentration until 1.5 × 10(-5) mol/L. A special focus was made on aggregation phenomenon as giant multilamellar "brainlike" vesicles were observed via cryogenic scanning electron microscopy (cryoSEM) and transmission electron microscopy (TEM; with a contrast agent) suggesting a high encapsulation ability and a very important specific surface of these particular organizations. PMID:21241066

Oumar, Mamadou; Taffin de Givenchy, Elisabeth; Dieng, Samba Yandé; Amigoni, Sonia; Guittard, Frédéric

2011-03-01

171

Molecular dynamics and free energy perturbation calculations on fluorocarbons and aspartyl protease inhibitors  

SciTech Connect

Molecular dynamics (MD) simulations of pure tetrafluoromethane and trifluoromethane were performed to determine the van der Waals parameters R[sup *] and [epsilon] for fluorine and for the hydrogen of trifluoromethane. The best values of R[sup *] and [epsilon] for fluorine were determined to be 1.75 [angstrom] and 0.061 kcal/mole. For the hydrogen, the optimal R[sup *] and [epsilon] were determined to be 1.21 [angstrom] and 0.015 kcal/mole. The relative free energies of aqueous solvation of several fluorinated derivatives of methane were calculated using the FEP method. The calculations duplicated the experimental free energies relatively well, but the calculation of the bond-potential of mean force (bond-PMF) contribution was necessary in order to get the most satisfactory agreement with experiment. In addition, results of an ethanol-to-ethane perturbation in aqueous solution show that the bond-PMF contribution is important even for FEP calculations not involving large changes in size if the length of a bond is changed during the perturbation. MD simulations were run to determine the structure of the waters solvating fluoromethane, trifluoromethane, and tetrafluoromethane. The calculated radical distribution functions and water orientations suggest that, on average, there is one water-fluorine hydrogen bond in the case of fluoromethane. In contrast, there is no evidence of water-flourine hydrogen-bonding in the cases of trifluoromethane or tetrafluoromethane. These results suggest that the greater aqueous solubility of fluromethane relative to trifluoromethane is largely due to the poorer quality of the water-fluorine electrostatic interactions in trifluoromethane.

Gough, C.A.

1992-01-01

172

Industrial Process Profiles for Environmental Use: Chapter 16. The Fluorocarbon-Hydrogen Floride Industry.  

National Technical Information Service (NTIS)

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 th...

H. E. Doorenbus T. Parsons

1977-01-01

173

NMR Evidence for the Molecular Stability of Production Fluorocarbon Polymers under Isothermal Aging at 70 deg C.  

National Technical Information Service (NTIS)

Several fluoropolymer binders were isothermally aged at 70 deg C for 12 months to study their molecular stability. These materials were aged by themselves and in admixture with their production related explosives. Fluorine and carbon-13 NMR analyses of th...

G. L. Clink

1986-01-01

174

NMR evidence for the molecular stability of production fluorocarbon polymers under isothermal aging at 70°C  

Microsoft Academic Search

Several fluoropolymer binders were isothermally aged at 70°C for 12 months to study their molecular stability. These materials were aged by themselves and in admixture with their production related explosives. Fluorine and carbon-13 NMR analyses of the acetone extracts of their isothermal residues were performed subsequent to their aging. No molecular modification of deterioration as a result of isothermal aging

Clink

1986-01-01

175

NMR evidence for the molecular stability of production fluorocarbon polymers under isothermal aging at 70/sup 0/C  

SciTech Connect

Several fluoropolymer binders were isothermally aged at 70/sup 0/C for 12 months to study their molecular stability. These materials were aged by themselves and in admixture with their production related explosives. Fluorine and carbon-13 NMR analyses of the acetone extracts of their isothermal residues were performed subsequent to their aging. No molecular modification of deterioration as a result of isothermal aging was detected.

Clink, G.L.

1986-02-01

176

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

NASA Technical Reports Server (NTRS)

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.

Niki, Hiromi

1990-01-01

177

Tropospheric Reactions of the Haloalkyl Radicals Formed from Hydroxyl Radical Reaction with a Series of Alternative Fluorocarbons.  

National Technical Information Service (NTIS)

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 (C...

R. Atkinson

1990-01-01

178

RECOVERY OF URANIUM HEXAFLUORIDE FROM A PROCESS GAS STREAM BY ABSORPTION DISTILLATION TECHNIQUES EMPLOYING A LIQUID FLUOROCARBON MEDIUM  

Microsoft Academic Search

Complete recovery of uranium hexafluoride from a nitrogen-uranium ; hexafluoride mixture was accomplished with a packed column absorption-; distillation system employing perfluorodimethylcyclohexane, CâFââ, as ; the sorbent. The pilot plant operated well on a continuous basis, and the ; limiting gas and liquid rates agreed well with those predicted from standard ; correlations. For absorption, values of the height of

R. A. Ebel; C. C. Littlefield; D. C. Brater; S. H. Smiley

1959-01-01

179

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

NASA Technical Reports Server (NTRS)

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.

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

2007-01-01

180

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

SciTech Connect

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.

Orkin, V.L.; Khamaganov, V.G.; Guschin, A.G.; Kasimovskaya, E.E.; Larin, I.K. [Institut Energeticheskiskh Problem Khimicheskoi Fiziki, Moscow (Russian Federation)

1993-04-01

181

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

SciTech Connect

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.

Hwang, F.S.; Hogen-Esch, T.E. [Univ. of Southern California, Los Angeles, CA (United States)

1995-04-24

182

Fluorocarbon based layer-by-layer etching of Si and SiO\\/sub 2\\/ - A molecular dynamics investigation  

Microsoft Academic Search

Summary form only given. As the critical dimensions in microelectronics devices shrink below 20 nm, it is becoming essential to control plasma etching processes on a sub-nm scale. Although atomic layer etching (ALE) techniques provide such dimensional precision, ALE etch rates are slow enough to be impractical for commercial applications. In this paper, we use a molecular dynamics (MD) model

S. Rauf; P. Ventzek; V. Smirnov; A. Stengach; K. Gaynullin; V. Pavlovsky

2006-01-01

183

Environmentally harmonious etching process for cleaning amorphous silicon and tungsten in chemical vapor deposition chamber  

Microsoft Academic Search

Novel cleaning process harmonized environmentally by using O2 plasma with a new fluorocarbon radical source has been developed for replacing the conventional process using green house gases, such as SF6 gas and fluorocarbon feed gases causing global warming. The new fluorocarbon radical source was designed to generate fluorocarbon reactive species from polytetrafluoroethylene (PTFE) by CO2 laser ablation. An electron cyclotron

Kazushi Fujita; Shigeto Kobayashi; Masafumi Ito; Masaru Hori; Toshio Goto

1999-01-01

184

Model of drug-loaded fluorocarbon-based micelles studied by electron-spin induced (19)f relaxation NMR and molecular dynamics simulation.  

PubMed

Rf-IPDU-PEGs belong to a class of fluoroalkyl-ended poly(ethylene glycol) polymers (Rf-PEGs), where the IPDU (isophorone diurethane) functions as a linker to connect each end of the PEG chain to a fluoroalkyl group. The Rf-IPDU-PEGs form hydrogels in water with favorable sol-gel coexistence properties. Thus, they are promising for use as drug delivery agents. In this study, we introduce an electron-spin induced 19F relaxation NMR technique to probe the location and drug-loading capacity for an electron-spin labeled hydrophobic drug, CT (chlorambucil-tempol adduct), enclosed in the Rf-IPDU-PEG micelle. With the assistance of molecular dynamics simulations, a clear idea regarding the structures of the Rf-IPDU-PEG micelle and its CT-loaded micelle was revealed. The significance of this research lies in the finding that the hydrophobic drug molecules were loaded within the intermediate IPDU shells of the Rf-IPDU-PEG micelles. The molecular structures of IPDU and that of CT are favorably comparable. Consequently, it appears that this study opens a window to modify the linker between the Rf group and the PEG chain for achieving customized structure-based drug-loading capabilities for these hydrogels, while the advantage of the strong affinity among the Rf groups to hold individual micelles together and to interconnect the micellar network is still retained in hopes of maintaining the sol-gel coexistence of the Rf-PEGs. PMID:18052082

Mathias, Errol V; Liu, Xiangli; Franco, Osmundo; Khan, Imran; Ba, Yong; Kornfield, Julia A

2008-02-01

185

Use of nanoparticles to make mineral oil lubricants feasible for use in a residential air conditioner employing hydro-fluorocarbons refrigerants  

Microsoft Academic Search

The application of nano-fluids in refrigerating systems is considered to be a potential way to improve the energy efficiency and reliability of HVAC&R facilities and to make economic the use of environment-friendly refrigerants. In this paper, we report a method that uses nanoparticles to enhance the energy efficiency of retrofitted residential air conditioners (RAC) employing HFCs as alternative refrigerants. The

Ruixiang Wang; Qingping Wu; Yezheng Wu

2010-01-01

186

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

NASA Astrophysics Data System (ADS)

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.

Xiang, H.; Komvopoulos, K.

2013-06-01

187

Characterization of polymer formation during SiO2 etching with different fluorocarbon gases (CHF3, CF4, C4F8)  

Microsoft Academic Search

In this paper, the polymer composition generated by three different combinations of gas chemistries for oxide etch are studied and the effects of different O2 plasma strip duration on polymer removal are also presented. The etch chemistries used were CHF3\\/CF4, CO\\/CF4\\/CHF3 and C4F8\\/CO\\/CHF3 chemistry. From the x-ray photoelectron spectroscopy (XPS) C 1s spectra, five distinct peaks are identified which correspond

Sang Y. Loong; H. K. Lee; Lap H. Chan; M. S. Zhou; F. C. Loh; Kuang L. Tan

1997-01-01

188

Gas-phase reactivity of lanthanide cations with fluorocarbons: C-F versus C-H and C-C bond activation  

SciTech Connect

The gas-phase reactivity of the fluorinated hydrocarbons CF{sub 4}, CHF{sub 3}, CH{sub 3}F, C{sub 2}F{sub 6}, 1,1-C{sub 2}H{sub 4}F{sub 2}, and C{sub 6}F{sub 6} with the lanthanide cations Ce{sup +}, Pr{sup +}, Sm{sup +}, Ho{sup +}, Tm{sup +}, and Yb{sup +} and the reactivity of C{sub 6}H{sub 5}F with all lanthanide cations Ln{sup +} (Ln = La-Lu, with the exception of Pm{sup +}) have been examined by Fourier-transform ion cyclotron resonance mass spectrometry. The perfluorinated compounds tetrafluoromethane and hexafluoroethane as well as trifluoromethane do not react with any lanthanide cation. Selective activation of the strong C-F bonds in fluoromethane, 1,1-difluoroethane, hexafluorobenzene, and fluorobenzene appears as a general reaction scheme along the 4f row. Experimental evidence is given for a `harpoon`-like mechanism for the F atom abstraction process which operates via an initial electron transfer from the lanthanide cation to the fluorinated substrate in the encounter complex Ln{sup +}RF. The most reactive lanthanides La{sup +}, Ce{sup +}, Gd{sup +}, and Tb{sup +} and also the formal closed-shell species Lu{sup +} exhibit additional C-H and C-C bond activation pathways in the reaction with fluorobenzene, namely dehydrohalogenation as well as loss of a neutral acetylene molecule. In the case of Tm{sup +} and Yb{sup +} the formation of neutral LnF{sub 3} is observed in a multistep process via C-C coupling and charge transfer. 17 refs., 2 figs., 2 tabs.

Cornehl, H.H.; Hornung, G.; Schwarz, H. [Technischen Unibersitaet Berlin (Germany)] [Technischen Unibersitaet Berlin (Germany)

1996-10-16

189

40 CFR 86.1327-96 - Engine dynamometer test procedures; overview.  

Code of Federal Regulations, 2010 CFR

...hot-start tests. The composite samples collected are...fluorocarbon-coated glass fiber filters or fluorocarbon-based...the beginning of the expansion section containing...inch (25 mm). The thermal conductivity of the...

2010-07-01

190

40 CFR 86.1327-96 - Engine dynamometer test procedures; overview.  

Code of Federal Regulations, 2010 CFR

...hot-start tests. The composite samples collected are...fluorocarbon-coated glass fiber filters or fluorocarbon-based...the beginning of the expansion section containing...inch (25 mm). The thermal conductivity of the...

2009-07-01

191

Environmentally harmonized plasma etching processes of amorphous silicon and tungsten  

Microsoft Academic Search

A novel etching process of a-Si and W for cleaning the CVD chamber employing ECR O2 plasma with injecting fluorocarbon radicals generated from a fluorocarbon radical source was developed for replacing green house gases such as SF6 gas and PFC gases. We proposed a new radical control method where the generated high order fluorocarbon radicals introduced into the plasma reactor

M. Hori; K. Fujita; S. Kobayashi; M. Ito; T. Goto

2000-01-01

192

Covalent chemical modification of self- assembled fluorocarbon monolayers by low- energy CH2Br2+· ions: a combined ion\\/surface scattering and X-ray photoelectron spectroscopic investigation  

Microsoft Academic Search

Specific covalent chemical modification at the outermost atomic layers of fluorinated self-assembled monolayers (F-SAMs) on gold is achieved by bombardment with low-energy polyatomic ions (<100 eV). The projectile ion CH2Br2 á (m\\/z 172), mass and energy selected using a hybrid ion\\/surface scattering mass spectrometer and scattered from the F-SAM surface, CF3(CF2)7(CH2)2-S-Au, undergoes ion\\/surface reactions evident from the nature of the

Nathan Wade; T. Pradeep; Jianwei Shen; R. Graham Cooks

1999-01-01

193

Direct Liquid Cooling of High Flux Micro and Nano Electronic Components Boiling, evaporation, jet, and spray cooling, by suitable liquids such as fluorocarbons, might serve to control chip hot-spots and overheating  

Microsoft Academic Search

The inexorable rise in chip power dissipation and emergence of on-chip hot spots with heat fluxes approaching 1k W\\/cm 2 has turned renewed attention to direct cooling with dielectric liquids. Use of dielectric liquids in intimate contact with the heat dissipating surfaces eliminates the deleterious effects of solid-solid interface resistances and harnesses the highly efficient phase-change processes to the critical

Avram Bar-Cohen; Mehmet Arik; Michael Ohadi

194

Efficiencies of transcritical CO 2 cycles with and without an expansion turbine  

Microsoft Academic Search

With the discovery that fluorocarbons may have a profoundly detrimental effect on the earth's atmosphere, it has become necessary to find a suitable replacement for a fluorocarbon-based refrigeration cycle. Such a replacement must perform comparably to current refrigerants, be economically feasible, and significantly reduce the possibility of a negative environmental impact compared with current refrigerants. A review of the literature

Douglas M. Robinson; Eckhard A. Groll

1998-01-01

195

Roughness and chemistry of silicon and polysilicon surfaces etched in high-density plasma: XPS, AFM and ellipsometry analysis  

Microsoft Academic Search

Surface chemistry and morphology of polysilicon thin films etched in a high-density fluorocarbon plasma under various conditions are studied by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and spectroscopic ellipsometry. XPS reveals the presence of a fluorocarbon layer, which composition and thickness depend on the plasma conditions. Ellipsometry measurements show the need to consider the superficial roughness. Surface roughness

Laëtitia Rolland; Christophe Vallée; Marie-Claude Peignon; Christophe Cardinaud

2000-01-01

196

Method of bonding diamonds in a matrix and articles thus produced  

DOEpatents

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.

Taylor, G.W.

1981-01-27

197

Utilization of oxygen difluoride for syntheses of fluoropolymers  

NASA Technical Reports Server (NTRS)

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.

Toy, M. S. (inventor)

1976-01-01

198

Development of a special purpose spacecraft coating, phase 4  

NASA Technical Reports Server (NTRS)

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.

Gillman, H. D.

1980-01-01

199

High performance rolling element bearing  

NASA Technical Reports Server (NTRS)

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.

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

200

Texturing polymer surfaces by transfer casting. [cardiovascular prosthesis  

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

201

Atmospheric trace gas measurements with a new clean air sampling system  

SciTech Connect

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.

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

1981-10-01

202

Development of an All-Metal Thick-Film Cost-Effective Metallization System for Solar Cells.  

National Technical Information Service (NTIS)

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 amb...

B. Ross

1981-01-01

203

Development of an All-Metal Thick-Film Cost-Effective Metallization System for Solar Cells. Quarterly Report No. 3, November 1980-April 1981.  

National Technical Information Service (NTIS)

Experimentation with screened electrodes made from fluorocarbon activated copper paste and silver fluoride activated copper paste is reported, including tape adhesion and scratch tests. Experiments were conducted with variations in past parameters, firing...

B. Ross

1981-01-01

204

Acute Oral Toxicity Evaluation and Genotoxicity Testing of Hexakis (2,2,2-Trifluornethoxy) Cyclotriphosphazene, A Replacement Candidate for Ozone Depleting Substances.  

National Technical Information Service (NTIS)

The DoD requires the development of toxicity profiles for chemical substitute candidates, that have little or no ozone depleting potential, to replace ozone depleting substances such as chloro- and fluorocarbons and halons. Hexakis (2,2,2-trifluoroethoxy)...

R. E. Wolfe D. H. Ellis H. F. Leahy A. Vinegar S. Sharma

1997-01-01

205

Synthesis and characterization of self-assembling water-soluble polymers.  

National Technical Information Service (NTIS)

The synthesis is proposed of water-soluble vinyl and other polymers capable of self-assembly through hydrophobic bonding of pendent fluorocarbon and other hydrophobic groups. The self-assembly process will be studied by viscometry and dynamic viscoelastic...

T. E. Hogen-Esch E. J. Amis

1992-01-01

206

Earth's Endangered Ozone  

ERIC Educational Resources Information Center

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)

Panofsky, Hans A.

1978-01-01

207

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...

208

Synthesis of new high performance lubricants and solid lubricants  

Microsoft Academic Search

Synthesis and testing was begun on a number of new classes of lubricants: perfluoropolyethers (branching effects), perfluoromethylene oxide ethers, chlorine-substituted fluorocarbon polyethers, fluorine-containing branched ether lubricants, glycerine- based perfluoropolyesters, perfluoro epoxy ether chains, etc.

Lagow

1993-01-01

209

Synthesis of new high performance lubricants and solid lubricants. Progress report, April 1992March 1993  

Microsoft Academic Search

Synthesis and testing was begun on a number of new classes of lubricants: perfluoropolyethers (branching effects), perfluoromethylene oxide ethers, chlorine-substituted fluorocarbon polyethers, fluorine-containing branched ether lubricants, glycerine- based perfluoropolyesters, perfluoro epoxy ether chains, etc.

Lagow

1993-01-01

210

Facile Synthesis for Functional Perfluoropolyether Oligomers, Diacids, Diesters, and Surfactants. (Reannouncement with New Availability Information).  

National Technical Information Service (NTIS)

Linear polyester precursors provide a convenient low cost synthesis for fluorocarbon surfactants, diacids, diesters, and intermediates. A reaction scheme starting with hydrocarbon linear polyesters followed by conversion of the ester to a perfluoro ester ...

D. F. Persico R. J. Lagow

1991-01-01

211

Synthesis of new high performance lubricants and solid lubricants. Progress report, April 1992--March 1993.  

National Technical Information Service (NTIS)

Synthesis and testing was begun on a number of new classes of lubricants: perfluoropolyethers (branching effects), perfluoromethylene oxide ethers, chlorine-substituted fluorocarbon polyethers, fluorine-containing branched ether lubricants, glycerine- bas...

R. J. Lagow

1993-01-01

212

Superhydrophobic lignocellulosic wood fiber/mineral networks.  

PubMed

Lignocellulosic wood fibers and mineral fillers (calcium carbonate, talc, or clay) were used to prepare paper samples (handsheets), which were then subjected to a fluorocarbon plasma treatment. The plasma treatment was performed in two steps: first using oxygen plasma to create nanoscale roughness on the surface of the handsheet, and second fluorocarbon deposition plasma to add a layer of low surface energy material. The wetting behavior of the resulting fiber/mineral network (handsheet) was determined. It was found the samples that were subjected to oxygen plasma etching prior to fluorocarbon deposition exhibit superhydrophobicity with low contact angle hysteresis. On the other hand, those that were only treated by fluorocarbon plasma resulted in "sticky" hydrophobicity behavior. Moreover, as the mineral content in the handsheet increases, the hydrophobicity after plasma treatment decreases. Finally, it was found that although the plasma-treated handsheets show excellent water repellency they are not good water vapor barriers. PMID:23957774

Mirvakili, Mehr Negar; Hatzikiriakos, Savvas G; Englezos, Peter

2013-09-25

213

"Proplast" for keratoprosthesis.  

PubMed

'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

White, J H; Gona, O

1988-05-01

214

Telemetry engineering and fabrication alternative soldering techniques for CFC elimination.  

National Technical Information Service (NTIS)

In an effort to eliminate the need for chlorinated fluorocarbons (CFCs) for several production assemblies in Telemetry Engineering and Fabrication, an alternate soldering reflow process to replace the current vapor phase system was needed. After analyzing...

R. V. Howard

1995-01-01

215

RT Mid-IR random lasing of Cr2+ doped ZnS, ZnSe, CdSe powders, polymer liquid and polymer films  

Microsoft Academic Search

We demonstrate room temperature (RT) middle-infrared (Mid-IR) random lasing of chromium- (Cr) doped ZnSe, ZnS, and CdSe powders, the powders imbedded in perfluorocarbon liquid polymer solutions, and fluorocarbon polymer films.

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

2009-01-01

216

Thermal stability of vapor phase deposited self-assembled monolayers for MEMS anti-stiction  

NASA Astrophysics Data System (ADS)

Six different source chemicals (organosilanes) were successfully used for deposition of self-assembled monolayers (SAMs) onto silicon substrates by a vapor phase process. Five different fluorocarbon coatings and one hydrocarbon coating were deposited. The thermal stability of the coatings was studied in detail with respect to degradation as a function of temperature, and for the fluorocarbon coatings also the degradation rate at 400 °C. For fluorocarbon coatings deposited from FDTS a useful lifetime of approximately 90 min at 400 °C was found allowing the coating to survive high temperature MEMS packaging operations, while fluorocarbon coatings deposited from FOTS, FOMDS, FOTES and FOMMS were less stable. The hydrocarbon coating deposited from OTS degrades already at approximately 200 °C. The thermal stability of the SAM coatings was found to be significantly reduced if aggregations from the deposition process are present on the coatings.

Zhuang, Yan Xin; Hansen, Ole; Knieling, Thomas; Wang, Christian; Rombach, Pirmin; Lang, Walter; Benecke, Wolfgang; Kehlenbeck, Markus; Koblitz, Jörn

2006-11-01

217

Synthesis of new high performance lubricants and solid lubricants. Progress report, April 1992--March 1993  

SciTech Connect

Synthesis and testing was begun on a number of new classes of lubricants: perfluoropolyethers (branching effects), perfluoromethylene oxide ethers, chlorine-substituted fluorocarbon polyethers, fluorine-containing branched ether lubricants, glycerine- based perfluoropolyesters, perfluoro epoxy ether chains, etc.

Lagow, R.J.

1993-04-01

218

Synthesis of new high performance lubricants and solid lubricants  

SciTech Connect

Synthesis and testing was begun on a number of new classes of lubricants: perfluoropolyethers (branching effects), perfluoromethylene oxide ethers, chlorine-substituted fluorocarbon polyethers, fluorine-containing branched ether lubricants, glycerine- based perfluoropolyesters, perfluoro epoxy ether chains, etc.

Lagow, R.J.

1993-04-01

219

An Experimental and Theoretical Investigation of the Magnetization Properties and Basic Electromechanics of Ferrofluids.  

National Technical Information Service (NTIS)

Ferrofluids are stable colloidal suspensions of sub-domain sized ferrite particles dispersed in a liquid medium by a suitable surfactant agent. Ferrofluids have been successfully prepared using water, hydrocarbons, esters, diesters, fluorocarbons, and eve...

T. B. Jones D. A. Krueger

1977-01-01

220

Diamond Growth on Carbide Surfaces Using a Selective Etching Technique.  

National Technical Information Service (NTIS)

Microwave plasma-enhanced chemical vapor deposition of diamond films on silicon carbide and tungsten carbide (with 6% cobalt) surfaces using fluorocarbon gases has been demonstrated. No diamond powder pre-treatment is necessary to grow these films with a ...

K. J. Grannen R. P. Chang

1993-01-01

221

Flame-resistant textiles  

NASA Technical Reports Server (NTRS)

Flame resistance treatment for acid resistant polyamide fibers involving photoaddition of fluorocarbons to surface has been scaled up to treat 10 yards of commercial width (41 in.) fabric. Process may be applicable to other low cost polyamides, polyesters, and textiles.

Fogg, L. C.; Stringham, R. S.; Toy, M. S.

1980-01-01

222

Research Concerning Ionic and Free Radical Reactions in Radiation Chemistry. Progress Report, September 15, 1976--September 15, 1977.  

National Technical Information Service (NTIS)

Progress is reported on ESR studies of fluorocarbon radicals and intermediate radicals. A detailed study was made of the dimethyl, diethyl, and di-n-propyl carbonates. Studies were continued on hydrogen-atom abstraction reactions at low temperatures with ...

T. F. Williams

1977-01-01

223

Migration of Flexible Packaging Components into Foods.  

National Technical Information Service (NTIS)

Solvent extractions were conducted on 4-foil-laminated materials with films of Lexan-polycarbonate, Rilsan-Nylon 11, Kodar-polyester, and Teflon-fluorocarbon. The film residues extracted were principally laminating adhesives which migrate through or perme...

R. L. Ferm

1966-01-01

224

A Comparative Study of Growth Process and Tribological Behavior between Single Component and Mixed Alkylsilane Self-Assembled Molecular Films  

Microsoft Academic Search

\\u000a In the present work, the growth process and tribological properties of single component and mixed alkylsilane self-assembled\\u000a molecular films were investigated. Atomic force microscopy (AFM) images showed that the growth process and morphology of the\\u000a single component fluorocarbon film was different from the mixed ones which were composed of fluorocarbon and hydrocarbon alkylsilane\\u000a molecules. Contact angle measurement showed that the

X. K. Wang; Y. H. Liu; J. B. Luo; X. C. Lu

225

Time resolved Langmuir probe measurements in inductively coupled plasmas  

Microsoft Academic Search

Summary form only given. There has been much interest in inductively coupled plasmas for semiconductor processing and for integrated optic applications. We are concerned with several processes using Inductively Coupled Plasma, such as deep silicon oxide etching using fluorocarbon gases (CF4, C2F6, CHF3) and their mixtures with methane (CH4) or hydrogen (H2), low-k etching using fluorocarbon gases mixed with oxygen

G. Cartry; D. Eon; V. Raballand; F. Gaboriau; M. C. Peignon; Ch. Cardinaud

2002-01-01

226

The liquid-vapor interface of a binary liquid mixture near the consolute point  

NASA Technical Reports Server (NTRS)

The present investigation is concerned with measurements of the reflectance of polarized light by the liquid-vapor interface above liquid mixtures of a fluorocarbon and an alcohol in the vicinity of the consolute point of the liquid mixture. The denser fluorocarbon is preferentially adsorbed at the interface. The denser fluorocarbon is preferentially adsorbed at the interface. The data are consistent with a simple model of the dielectric constant vs height profile in the interface region. Liquid mixtures of isopropanol (i-C3H7OH) and perfluoromethylcyclohexane (C7F14) near their consolute point (Tc = 363 K) are utilized in the conducted experiments. The primary quantity measured is the ellipticity as a function of temperature and liquid composition. Attention is given to details regarding the experimental techniques, model dielectric constant profiles, and the calculation of the ellipticity.

Schmidt, J. W.; Moldover, M. R.

1985-01-01

227

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

NASA Technical Reports Server (NTRS)

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.

Ross, B.; Parker, J.

1982-01-01

228

Vacuum ultraviolet radiation/atomic oxygen synergism in materials reactivity  

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

229

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

SciTech Connect

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.

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

2000-02-02

230

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

NASA Technical Reports Server (NTRS)

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.

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

1977-01-01

231

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

SciTech Connect

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%.

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

2000-02-02

232

Sealants for solar collectors  

Microsoft Academic Search

Elastomeric sealants employed in thermal solar collectors are subjected to extremely harsh conditions. In order to function properly for long periods of time, they must exhibit good resistance to environmental factors such as high and low temperature extremes, oxygen, ozone, water, and ultraviolet radiation. Several types of candidate elastomers consisting of fluorocarbon, silicone, acrylic, ethylene-acrylic, ethylene-propylene terpolymer, and butyl and

M. A. Mendelson; Russell M. Luck; Fred A. Yeoman; Francis W. Navish

1981-01-01

233

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

NASA Astrophysics Data System (ADS)

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.

Ross, B.

1981-09-01

234

PLASTICS FOR USE IN RADIATION FIELDS. I. EFFECT OF GAMMA RADIATION ON THE PHYSICAL PROPERTIES OF PLASTICS  

Microsoft Academic Search

Data are given on the effects of gamnda radiation on the physical ; properties of plastics classified as polycarbonate, polyethylene, fluorocarbon, ; polyamide, polyester, reinforced, silicone, and vinyl. The irradiations were ; carried out in air at ambient temperature and normal atmospheric pressure to ; various doses up to l x 10\\/sup⁹r depending upon the stability of the ; materials

1961-01-01

235

Tumor Oxygen Dynamics: Correlation of In Vivo MRI with Histological Findings1  

Microsoft Academic Search

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 dynam- ics in the two Dunning prostate R3327

Dawen Zhao; Sophia Ran; Anca Constantinescu; Eric W. Hahn; Ralph P. Mason

236

Pretreatment of Kapton-coated cable for epoxy adhesion  

Microsoft Academic Search

A new system to protect bonded strain gages that will be attached to the MFTF magnets was tested and indicated falling electrical resistance to ground, which is attributed to the infiltration of moisture. The most likely infiltration route seemed to be along the Kapton lead cable, which has an outer space of FEP fluorocarbon resin. The treated ends are embedded

J. F. Carley

1984-01-01

237

Role of interfacial adhesion strength on toughening polypropylene with rigid particles  

Microsoft Academic Search

The effects of interfacial adhesion strength on the mechanical properties of composites of polypropylene and glass particles were investigated. The 3.5 ?m average diameter glass particles were surface-treated using two silanes with different functional groups. The functional groups were hydrocarbons, expected to promote adhesion between filler and matrix, and fluorocarbons, expected to reduce the strength of adhesion. Mixtures of the

Y. S. Thio; A. S. Argon; R. E. Cohen

2004-01-01

238

Water-based intumescent paint  

NASA Technical Reports Server (NTRS)

Article discusses fire-resistant water-based paints made by adding intumescing agents to fluorocarbon coatings. Since these paints are water-based, they do not pollute atmosphere as they dry and can be used in closed-loop air-recirculation system in spacecraft and submarines.

Sauers, D. G.; Nannelli, P.

1979-01-01

239

Inspection of small multi-layered plastic tubing during extrusion, using low-energy X-ray beams  

Microsoft Academic Search

The automotive industry uses nylon tubing with a thin ETFE (ethylene-tetrafluroethylene) inner layer to carry fuel from the tank to the engine. This fluorocarbon inner barrier layer is important to reduce the migration of hydrocarbons into the environment. Pilot Industries has developed a series of real-time inspection stations for dimensional measurements and flaw detection during the extrusion of this tubing.

C. Armentrout; T. Basinger; J. Beyer; B. Colesa; P. Olsztyn; K. Smith; C. Strandberg; D. Sullivan; J. Thomson

1999-01-01

240

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

Microsoft Academic Search

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.

B. Ross; J. Parker

1982-01-01

241

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...

242

46 CFR 77.30-10 - Stowage.  

Code of Federal Regulations, 2010 CFR

...Self-contained breathing apparatus for refrigeration 1 Flame safety lamps Ocean and...Required only on vessels equipped with any refrigeration unit using ammonia to refrigerate...more than 20 cubic feet or with any refrigeration unit using fluorocarbons to...

2010-10-01

243

46 CFR 77.30-10 - Stowage.  

Code of Federal Regulations, 2011 CFR

...Self-contained breathing apparatus for refrigeration 1 Flame safety lamps Ocean and...Required only on vessels equipped with any refrigeration unit using ammonia to refrigerate...more than 20 cubic feet or with any refrigeration unit using fluorocarbons to...

2011-10-01

244

Fat resistance properties of chitosan-based paper packaging for food applications  

Microsoft Academic Search

The objective of this study was to potentially replace fluorocarbon-treatment of paper-based materials by chitosan coating to produce oil barrier packaging. With this work, the nature of interactions existing between fatty acids, chosen as model lipids (such as oleic acid, largely present in the food field), and chitosan was particularly investigated. The influence of the fatty acid content and the

F. Ham-Pichavant; G. Sèbe; P. Pardon; V. Coma

2005-01-01

245

Plasma lithography — thin-film patterning of polymers by RF plasma polymerization II: Study of differential binding using adsorption probes  

Microsoft Academic Search

In this study we present methods to physico-chemically modify micropatterned cell culture substrates that were manufactured using plasma lithography to incorporate affinity structures for specific cell binding. The surfaces consist of a pattern of a fluorocarbon plasma polymer with feature sizes between 5 and 100 ?m on a background of a non-fouling tetraglyme (tetraethylene glycol dimethyl ether) plasma polymer. The

Andreas Goessl; Stephen L. Golledge; Allan S. Hoffman

2001-01-01

246

Gas mixtures for spark gap closing switches  

DOEpatents

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.

Christophorou, Loucas G. (Oak Ridge, TN); McCorkle, Dennis L. (Knoxville, TN); Hunter, Scott R. (Oak Ridge, TN)

1988-01-01

247

Gas mixtures for spark gap closing switches  

DOEpatents

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.

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

1987-02-20

248

The use of small-scale test data to characterize some aspects of fire fighting foam for suppression modeling  

Microsoft Academic Search

Concerns have been raised about the environmental impact of fluorocarbon-based fire fighting foams. To aid in developing alternative fire fighting foam formulations, fire suppression models are being constructed to evaluate the performance of new, innovative formulations. Some of the input parameters for the fire suppression models are specific to the foam and need to be measured experimentally. A small-scale test

Brian Y Lattimer; Christopher P Hanauska; Joseph L Scheffey; Frederick W Williams

2003-01-01

249

Assessment of Dispersing Tracer Gas with Ventilation Air Stream to Detect Mine Fires.  

National Technical Information Service (NTIS)

A remote heat-activiated stench gas-tracer gas mine alarm system was developed to reduce the time between fire detection and personnel notification. The stench gas-tracer gas system contains ethyl mercaptan for personnel warning and a fluorocarbon for tra...

M. D. Marshall

1983-01-01

250

CF, CFâ and SiF Densities in Inductively Driven Discharges Containing CâFâ, CâFâ and CHFâ  

Microsoft Academic Search

Laser induced fluorescence was used to measure the spatially resolved CF, CFâ and SiF radical density in inductively driven discharges containing fluorocarbon gases. Measurements of the spatially resolved CF density were performed in CâFâ and CHFâ containing discharges as functions of inductive power, pressure and bias condition on a silicon substrate. In addition, CF rotational temperatures were calculated, assuming saturated

GREGORY A

2000-01-01

251

Uv Protective Coatings for Heliostats and the Plastic Dome. Final Technical Report.  

National Technical Information Service (NTIS)

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 silver...

B. Baum E. Bansleben P. McGrath

1981-01-01

252

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

NASA Technical Reports Server (NTRS)

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.

Ross, B.

1981-01-01

253

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

Microsoft Academic Search

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

Robert C. McDonald; Jerome Pickett; Franz Goebel

1991-01-01

254

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...

255

Review of solid adsorption solar refrigerator I: an overview of the refrigeration cycle  

Microsoft Academic Search

A review of the practically realized solid adsorption solar refrigeration cycles is presented. The cycles also have potentials for use as heat pumps. They have been classified according to the adsorbate utilized as: cycles with water as refrigerant, cycles using fluorocarbon as refrigerant, cycles using ammonia as refrigerant and cycles with alcohols as refrigerant. The performances of these refrigeration cycles,

E. E Anyanwu

2003-01-01

256

Coolant controversy heats up  

Microsoft Academic Search

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

Shanley

1997-01-01

257

Perfluorocyclobutane (PFCB) polyaryl ethers: versatile coatings materials  

Microsoft Academic Search

The cyclopolymerization of aromatic trifluorovinyl ether (TFVE) monomers offers a versatile route to a unique class of linear and network fluoropolymers containing the perfluorocyclobutyl (PFCB) linkage. Polymerization proceeds by a thermal — radical mediated — step-growth mechanism and provides well-defined polymers containing known fluoroolefin end groups. PFCB polymers combine the engineering thermoplastic nature of polyaryl ethers with fluorocarbon segments and

Dennis W. Smith Jr; David A. Babb; Hiren V. Shah; Adrienne Hoeglund; R. Traiphol; Dvora Perahia; Harold W Boone; Charles Langhoff; Mike Radler

2000-01-01

258

Research Progress in Calenderable Fluorosilicone with Excellent Fuel Resistance  

Microsoft Academic Search

Fluorosilicone rubber (FSR) is a high performance elastomer for applications requiring low temperature flexibility, high temperature stability, and fuel resistance. This paper describes the relationship between the fluorosilicone chemical structure and material properties. In terms of fuel resistance and low temperature flexibility, fluorosilicone is compared to other elastomers such as fluorocarbon rubber (FKM) and standard silicone rubber (MQ\\/VMQ\\/PVMQ). The application

Haibing Zhang

259

Polymerization of Perfluoro Epoxides  

Microsoft Academic Search

Epoxidation of perfluoroolefins to perfluoroepoxides has made a new class of monomers available. Perfluoroepoxides undergo facile ring-opening reactions with nucleophiles which under the proper reaction conditions can lead either to poly-perfluoroethers or to other classes of fluorocarbons previously unavailable or available with great difficulty. The preparation of perfluoroepoxides is described.

H. S. Eleuterio

1972-01-01

260

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

NASA Astrophysics Data System (ADS)

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.

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

2013-05-01

261

Fluids and Elastomers for Low-Temperature Heat Transfer and Hydraulic Systems  

Microsoft Academic Search

Five fluids (a dimethyl silicone, a silicate ester, a branched chain chloro-fluorocarbon, a cyclic fluorinated ether and a fluorinated polyether) were evaluated for use as the fluid in a single pass, gas actuated hydraulic system capable of operation from ?150 to 275 F. Important physical and chemical properties, including thermal stability, lubricity, viscosity, pour, low-temperature characteristics and flash point, were

C. S. Armstrong

1966-01-01

262

46 CFR 77.30-10 - Stowage.  

Code of Federal Regulations, 2013 CFR

...Self-contained breathing apparatus for refrigeration 1 Flame safety lamps Ocean and...Required only on vessels equipped with any refrigeration unit using ammonia to refrigerate...more than 20 cubic feet or with any refrigeration unit using fluorocarbons to...

2013-10-01

263

Acute Inhalation Toxicity Evaluation of a 93:7 Mixture of Perfluoro-2- Butene and 1 -Bromopropane, a Replacement Candidate for Ozone Depleting Substances.  

National Technical Information Service (NTIS)

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...

M. L. Feldmann H. F. Leahy A. Vinegar

1997-01-01

264

Surface modification of perfluorosulfonic acid membranes with perfluoroheptane (C 7F 16)\\/argon plasma  

Microsoft Academic Search

This research focuses on the surface modification of a perfluorosulfonic acid (PFSA) membrane using plasma treatment. The plasma gas was a mixture of perfluoroheptane (C7F16) and argon (Ar). The results indicated that the plasma mixture led to the deposition of a thin fluorocarbon polymerized top layer onto the PFSA membrane. The effects of plasma operating conditions (plasma power, reactor pressure,

Shingjiang Jessie Lue; Shiang-Yiaw Hsiaw; Ta-Chin Wei

2007-01-01

265

Environmentally benign etching process of amorphous silicon and tungsten using species evaporated from polytetrafluoroethylene and fluorinated ethylene propylene  

Microsoft Academic Search

Environmentally benign etching process of amorphous silicon (a-Si) and tungsten (W) by using a plasma process with an evaporation of solid materials system has been developed for replacing a conventional plasma process using green house gases, such as SF6 gas and perfluorocompound gases causing global warming. The evaporation system was designed to generate fluorocarbon species from solid materials by a

Kazushi Fujita; Masaru Hori; Toshio Goto; Masafumi Ito

2003-01-01

266

Method of cooling zinc halogen batteries  

Microsoft Academic Search

This disclosure relates to a method of cooling zinc halogen batteries which involves the use of a liquid-overfeed cooling system utilizing a fluorocarbon refrigerant or the like. This new method is adaptable for use in either cooling the battery store water during charge so that a solid halogen hydrate will form, or for use in cooling the battery electrolyte, or

Kodali

1981-01-01

267

New main-chain crown-ether polyimides for lithium-ion battery membranes  

Microsoft Academic Search

Thin rugged membranes based on polyimides having a columnar liquid crystal (LC) morphology (nanotubules of crown ether) which rapidly conduct lithium ions between the anode and cathode is the objective. This preliminary report describes the synthesis and characterization of a novel lithium-ion conducting polymer containing crown ether segments in the backbone. Segments of fluorocarbon co-monomers were used to lower cohesive

G. A. Lindsay; M. H. Miles; P. Zarras; S. Fallis; R. Y. Yee; A. P. Chafin; L. H. Merwin

1999-01-01

268

46 CFR 128.410 - Ship's service refrigeration systems.  

Code of Federal Regulations, 2013 CFR

No self-contained unit either for air-conditioning or for refrigerated spaces for ship's stores need comply with § 58.20-5, 58.20-10, 58.20-15, 58.20-20(a), or 58.20-20(b) of this chapter ifâ (a) The unit uses a fluorocarbon refrigerant allowed by part 147 of this...

2013-10-01

269

46 CFR 128.410 - Ship's service refrigeration systems.  

Code of Federal Regulations, 2010 CFR

No self-contained unit either for air-conditioning or for refrigerated spaces for ship's stores need comply with § 58.20-5, 58.20-10, 58.20-15, 58.20-20(a), or 58.20-20(b) of this chapter ifâ (a) The unit uses a fluorocarbon refrigerant allowed by part 147 of this...

2009-10-01

270

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

NASA Technical Reports Server (NTRS)

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.

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

1978-01-01

271

Black silicon method XI: oxygen pulses in SF6 plasma  

Microsoft Academic Search

A detailed study is performed to understand and show the potential of high-speed, deep reactive ion etching (DRIE) of silicon using oxygen inhibitor pulses as a replacement for hydro-fluorocarbons (HFCs). This process might be considered the 'holy grail' in DRIE as the environmental restrictions for the use of HFCs are becoming increasingly stronger. When compared to the usual cryogenic mixed

H. V. Jansen; M. J. de Boer; K. Ma; M. Gironès; S. Unnikrishnan; M. C. Louwerse; M. C. Elwenspoek

2010-01-01

272

Analysis and Kinetics of Transient Species in Electrode Near Plasma and Plasma Boundary Sheath of RF Plasmas in Molecular Gases  

Microsoft Academic Search

Modern diagnostic methods are applied for investigation of spatial and temporal behaviour of selected reac- tive species in oxygen and fluorocarbon rf plasmas. Comprehensive investigations of the spatial distribution of atomic oxygen were done by means of two-photon absorption laser induced fluorescence spectroscopy. Ex- emplarily, axial and radial O-concentrations are shown for an asymmetric capacitively coupled rf plasma in pure

M. Geigl; S. Peters; O. Gabriel; B. Krames; J. Meichsner

2005-01-01

273

Measurements of the electron energy distribution function in molecular gases in an inductively coupled plasma  

Microsoft Academic Search

A tuned, cylindrical Langmuir probe has been used to measure the electron energy distribution function (EEDF) in atomic and molecular gases in an inductively coupled plasma. We have discussed the precautions necessary for making Langmuir probe measurements in fluorocarbon plasmas. The ionic and neutral composition of the plasma is measured using mass spectrometry. While the EEDFs in argon are non-Maxwellian,

Harmeet Singh; David B. Graves

2000-01-01

274

Ozone mass transfer in an ozone–water contacting process with Shirasu porous glass (SPG) membranes—A comparative study of hydrophilic and hydrophobic membranes  

Microsoft Academic Search

Ozone absorption into water in a bubble-free ozone–water contacting process was investigated with tubular hydrophilic and hydrophobized Shirasu porous glass (SPG) membranes having uniform pores to gain a better understanding of the membrane's role in the ozone transfer. The surface of SPG membranes was hydrophobized by chemical modification with an organosilane having a fluorocarbon functional group. At a water flow

Masato Kukuzaki; Kanji Fujimoto; Shinji Kai; Kaoru Ohe; Tatsuya Oshima; Yoshinari Baba

2010-01-01

275

Greenhouse effect of chlorofluorocarbons and other trace gases  

Microsoft Academic Search

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

James Hansen; Andrew Lacis; Michael Prather

1989-01-01

276

Lighter-than-Air Science  

ERIC Educational Resources Information Center

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…

MOSAIC, 1977

1977-01-01

277

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...

278

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

ERIC Educational Resources Information Center

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)

Richmond, Thomas G.

1995-01-01

279

Synthesis and applications of surfactants containing fluorine  

Microsoft Academic Search

Syntheses and solution properties of novel fluorinated surfactants with branched tail, especially on anionic surfactants having two polyfluoroalkyl chains and on anionic surfactants having different hydrophobic chains (hybrid surfactants), are reviewed. For example, when the fluorocarbon chain length in the surfactants possessing two polyfluoroalkyl chains increases, the Krafft points and the area of surfactant molecule at the air-water interface increases,

Masahiko Abe

1999-01-01

280

Highly fluorinated amphiphiles and colloidal systems, and their applications in the biomedical field. A contribution.  

PubMed

Fluorocarbons and fluorocarbon moieties are uniquely characterized by very strong intramolecular bonds and very weak intermolecular interactions. This results in a combination of exceptional thermal, chemical and biological inertness, low surface tension, high fluidity, excellent spreading characteristics, low solubility in water, and high gas dissolving capacities, which are the basis for innovative applications in the biomedical field. Perfluoroalkyl chains are larger and more rigid than their hydrogenated counterparts. They are considerably more hydrophobic, and are lipophobic as well. A large variety of well-defined, modular fluorinated surfactants whose polar head groups consist of polyols, sugars, sugar phosphates, amino acids, amine oxides, phosphocholine, phosphatidylcholine, etc, has recently been synthesized. Fluorinated surfactants are significantly more surface active than their hydrocarbon counterparts, both in terms of effectiveness and of efficiency. Despite this, they are less hemolytic and less detergent. Fluorosurfactants appear unable to extract membrane proteins. Fluorinated chains confer to surfactants a powerful driving force for collecting and organizing at interfaces. As compared to non-fluorinated analogs, fluorosurfactants have also a much stronger capacity to self-aggregate into discrete molecular assemblies when dispersed in water and other solvents. Even very short, single-chain fluorinated amphiphiles can form highly stable, heat-sterilizable vesicles, without the need for supplementary associative interactions. Sturdy microtubules were obtained from non-chiral, non-hydrogen bonding single-chain fluorosurfactants. Fluorinated amphiphiles can be used to engineer a variety of colloidal systems and manipulate their morphology, structure and properties. Stable fluorinated films, membranes and vesicles can also be prepared from combinations of standard surfactants with fluorocarbon/hydrocarbon diblock molecules. In bilayer membranes made from fluorinated amphiphiles the fluorinated tails segregate to form an internal teflon-like hydrophobic and lipophobic film that increases the stability of the membrane and reduces its permeability. This fluorinated film can also influence the behavior of fluorinated vesicles in a biological milieu. For example, it can affect the in vivo recognition and fate of particles, or the enzymatic hydrolysis of phospholipid components. Major applications of fluorocarbons currently in advanced clinical trials include injectable emulsions for delivering oxygen to tissues at risk of hypoxia; a neat fluorocarbon for treatment of acute respiratory failure by liquid ventilation; and gaseous fluorocarbon-stabilized microbubbles for use as contrast agents for ultrasound imaging. Fluorosurfactants also allow the preparation of a range of stable direct and reverse emulsions, microemulsions, multiple emulsions, and gels, some of which may include fluorocarbon and hydrocarbon and aqueous phases simultaneously. Highly fluorinated systems have potential for the delivery of drugs, prodrugs, vaccines, genes, markers, contrast agents and other materials. PMID:9782389

Krafft, M P; Riess, J G

1998-01-01

281

Pretreatment of Kapton-coated cable for epoxy adhesion  

NASA Astrophysics Data System (ADS)

A new system to protect bonded strain gages that will be attached to the MFTF magnets was tested and indicated falling electrical resistance to ground, which is attributed to the infiltration of moisture. The most likely infiltration route seemed to be along the Kapton lead cable, which has an outer space of FEP fluorocarbon resin. The treated ends are embedded in the 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. It is shown 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. It appears that the 40-s exposure to Tetra-Etch has penetrated the 0.5 mil fluorocarbon coating and attacks the Kapton film and the conductor coatings inside it.

Carley, J. F.

1984-01-01

282

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

NASA Technical Reports Server (NTRS)

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.

Wheeler, Donald R.; Pepper, Stephen V.

1990-01-01

283

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

NASA Technical Reports Server (NTRS)

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.

Wheeler, Donald R.; Pepper, Stephen V.

1990-01-01

284

Mixed micellar phases of nonmiscible surfactants: mesoporous silica with bimodal pore size distribution via the nanocasting process.  

PubMed

Highly organized mesoporous silica monoliths were reproducibly prepared by nanocasting mixtures of fluorinated nonionic surfactants and micelles of two hydrocarbon block copolymers. It is the special feature of this fluorocarbon/hydrocarbon template mixture that they form not mixed micelles but individual micelles instead. By careful analysis of the pore architectures by gas sorption measurements and transmission electron microscopy in dependence on the relative template concentration, two different situations could be identified: (a) mesoscopically demixed samples and (b) mixed micellar phases where the two different micelles are packed in some type of organized alloy phase. Besides identification of such mixed phases for the first time for fluorocarbon/hydrocarbon mixtures, the resulting porous systems with controlled bimodal pore size distribution might be interesting from a materials perspective. PMID:15323535

Groenewolt, Matthijs; Antonietti, Markus; Polarz, Sebastian

2004-08-31

285

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

NASA Astrophysics Data System (ADS)

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.

Sokolova, Anastasiya

286

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)

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.

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

2013-05-01

287

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

NASA Technical Reports Server (NTRS)

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.

Pei, Xiong-Skiba

1999-01-01

288

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

NASA Technical Reports Server (NTRS)

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.

Willis, P. B.; Baum, B.

1977-01-01

289

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

NASA Astrophysics Data System (ADS)

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.

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

2011-08-01

290

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

NASA Technical Reports Server (NTRS)

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.

1990-01-01

291

Green fluorescent organic light-emitting device with external quantum efficiency of nearly 10%  

Microsoft Academic Search

Green fluorescent organic light-emitting device (OLED) exhibiting a high external quantum efficiency of nearly 10% has been developed. The OLED consists of simple three organic layers, using NPB, 0.8% C545T doped TPBA, and DBzA as a hole-transporting layer, an emitting layer, and an electron-transporting layer, respectively, [fluorocarbon coated indium tin oxide\\/NPB (60 nm)\\/08% C545T doped TPBA (40 nm)\\/DBzA (20 nm)\\/LiF

Kenji Okumoto; Hiroshi Kanno; Yuji Hamaa; Hisakazu Takahashi; Kenichi Shibata

2006-01-01

292

High performance organic field-effect transistors with fluoropolymer gate dielectric  

Microsoft Academic Search

Electrical stability is essential for a successful commercialization of organic semiconductor devices. We report on organic field-effect transistors with unprecedented electrical stability. The single crystal and thin-film transistors employ a fluorocarbon polymer as gate dielectric (CytopTM) and pentacene or rubrene as the organic semiconductor. CytopTM (Cyclic Transparent Optical Polymer) is easy to be used and can be deposited in air

Wolfgang L. Kalb; Thomas Mathis; Simon Haas; Arno F. Stassen; Bertram Batlogg

2007-01-01

293

The usefulness of the Lifshitz–van der Waals\\/acid–base approach for surface tension components and interfacial tensions  

Microsoft Academic Search

The Lifshitz–van der Waals\\/acid-base approach proposed by van Oss et al. is found to yield inconsistent solid surface tensions and components from contact angles, for fluorocarbon, polystyrene, and poly(methyl methacrylate) solid surfaces. It is also shown that the approach cannot predict the correct interfacial tensions of all liquid–liquid pairs in question: the predicted interfacial tensions range from 34% lower to

D. Y. Kwok

1999-01-01

294

Evisceration implant of Proplast II. A preliminary report.  

PubMed

An evisceration implant made from a highly porous inert, Teflon fluorocarbon, Proplast II, and the surgical technique of implantation is described. The implant was used in four eyes without complications. The implant and technique have many advantages: the ability to absorb antibiotics: the ability to prevent extrusion and infection; the fact that it is lightweight, black in color, and capable of preserving the cornea. PMID:2285667

Girard, L J; Esnaola, N; Sagahon, E

1990-01-01

295

Free Ion 4fn Levels of the Tetravalent Lanthanides. Fluorescence and Absorption Spectra of Cesium Dysprosium (IV) Heptafluoride  

Microsoft Academic Search

When a mixture of chloride or sulfate salts of cesium and dysprosium in a 3:1 mole ratio was treated with fluorine gas at 10-60 psig and 200°-350°C, the white Dy(III) starting material was converted to an orange compound with an empirical formula approaching Cs3DyF7. Fluorescence and infrared absorption spectra of fluorocarbon mulls of the orange fluorination product, measured at liquid

Louis P. Varga; Larned B. Asprey

1968-01-01

296

Antisoiling Coatings for Solar-Energy Devices  

NASA Technical Reports Server (NTRS)

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.

Cuddihy, E. F.; Willis, P.

1986-01-01

297

Reduced J-tube pull force  

Microsoft Academic Search

A method is described for reducing the force required to move a pipe through a J-tube attached to an offshore platform and for reducing corrosion at the interface between air and salt water in the J-tube comprising: introducing a mixture of fluorocarbon polymer and a hydrocarbon carrier into the J-tube, the mixture having a lower specific gravity than water; and

Esparza

1988-01-01

298

Climate Change, Air Pollution, and the Economics of Health Impacts  

Microsoft Academic Search

Climate change and air pollution are intricately linked. The distinction between greenhouse substances and other air pollutants is resolved at least for the time being in the context of international negotiations on climate policy through the identification of CO2, CH4, N2O, SF6 and the per- and hydro- fluorocarbons as substances targeted for control. Many of the traditional air pollutant emissions

J. Reilly; T. Yang; S. Paltsev; C. Wang; R. Prinn; M. Sarofim

2003-01-01

299

Microfluidic chip for biochemical reaction and electrophoretic separation by quantitative volume control  

Microsoft Academic Search

We have developed a microfluidic integrated chip with all the fluidic manipulations required for biochemical reaction and electrophoretic separation. The microchip was fabricated using standard photolithography, isotropic wet etching, liftoff patterning of fluorocarbon film, and polydimethylsiloxane replica molding. The fabricated microfluidic chip (46mm×25mm) was composed of two nanoliter-metering microchannel networks, a serpentine mixing channel, a sample injector, and an electrophoretic

Sang-Ho Lee; Seung Il Cho; Chang-Soo Lee; Byung-Gee Kim; Yong-Kweon Kim

2005-01-01

300

Update on fluoroelastomers: from perfluoroelastomers to fluorosilicones and fluorophosphazenes  

Microsoft Academic Search

A survey of the synthesis, properties and applications of fluoroelastomers is reported falling into two main parts. After describing commercially available (per)fluorocarbon elastomers, fluoro-phosphazenes and silicones, recent data on hybrid fluorosilicones containing longer chains (often fluorinated) between silicon atoms are supplied. The second part deals with well-architectured fluoroelastomers. First, fluorinated thermoplastic elastomers obtained either by sequential iodine transfer polymerisation of

Bruno Ameduri; Bernard Boutevin

2005-01-01

301

Effects of simulant mixed waste on EPDM and butyl rubber  

Microsoft Academic Search

The authors have developed a Chemical Compatibility Testing Program for the evaluation of plastic packaging components which may be used in transporting mixed waste forms. In this program, they have screened 10 plastic materials in four liquid mixed waste simulants. These plastics were butadiene-acrylonitrile copolymer (Nitrile) rubber, cross-linked polyethylene, epichlorohydrin rubber, ethylene-propylene (EPDM) rubber, fluorocarbons (Viton and Kel-F{trademark}), polytetrafluoro-ethylene (Teflon),

P. J. Nigrey; T. G. Dickens

1997-01-01

302

Novel fluorohydrocarbons  

NASA Technical Reports Server (NTRS)

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.

Scherer, Kirby V. (Inventor)

1979-01-01

303

Electrochemical carbyne from perfluorinated hydrocarbons: Synthesis and stability studied by Raman scattering  

Microsoft Academic Search

The synthesis of electrochemical carbyne from perfluorinated hydrocarbons was optimized. The relative yield of carbyne was monitored by Raman spectroscopy using the C?C stretching mode. The position and relative intensity of this band depend on the type of fluorocarbon and reducing agent used. Optimum conditions were attained for electrochemical reduction of poly(tetrafluoroethylene) with K- or Na-amalgams. Poly(tetrafluoroethylene) oriented by mechanical

Johann Kastner; Hans Kuzmany

1995-01-01

304

A low temperature biochemically compatible bonding technique using fluoropolymers for biochemical microfluidic systems  

Microsoft Academic Search

A new low temperature biochemically compatible bonding technique using fluoropolymers has been developed in this work and characterized in terms of mechanical bonding strength and biochemical resistance. This bonding technique uses a spin-on Teflon-like amorphous fluorocarbon polymer (CYTOPTM) as a bonding interface layer. The developed bonding process requires a bonding temperature of 160°C and the bonding strength attained from the

Arum Han; Kwang W. Oh; Shekhar Bhansali; H. Thurman Henderson; Chong H. Ahn

2000-01-01

305

Metallic and nonmetallic coatings for ICF targets  

Microsoft Academic Search

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

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

1981-01-01

306

Formation of C2 Radicals in High-Density C4F8 Plasmas Studied by Laser-Induced Fluorescence  

Microsoft Academic Search

Spatial and temporal variations of C2 radical density in high-density C4F8 plasmas have been investigated by laser-induced fluorescence (LIF) spectroscopy. Hollow-shaped spatial distributions have been observed for the C2 density, indicating that C2 radicals are produced from fluorocarbon film on the chamber wall and are lost in the plasma column by electron impact processes. The C2 density depends largely on

Chihiro Suzuki; Koichi Sasaki; Kiyoshi Kadota

1999-01-01

307

Synergistic Toxicity and Carcinogenicity of `Freons' and Piperonyl Butoxide  

Microsoft Academic Search

`FREONS' are fluorocarbons, with 1-4 carbon atoms, fluorine and sometimes chlorine, bromine or hydrogen, which are widely used as propellants (for example, with pressurized aerosols of foods or pesticides), fire extinguishers, solvents, and refrigerants. `Freons' have low toxicity after acute or chronic inhalation exposures1,2, with the exception of halothane, CF3-CHBrCl, which has produced occasional hepatotoxicity, possibly as a result of

Samuel S. Epstein; S. Joshi; J. Andrea; P. Clapp; H. Falk; N. Mantel

1967-01-01

308

A new concept for very low energy detonators and torches  

Microsoft Academic Search

We deposited secondary explosive and multilayer thermite films directly onto semiconductor bridges (SCBs) and other substrates. Methods for the deposition of two thermite films (aluminum\\/copper oxide and magnesium\\/fluorocarbon polymer) were developed as part of this study and a new capability was obtained for depositing adherent films on any material, including Teflon and Gore-Tex. Our experimental program determined conditions for the

R. W. Jr. Bickes; M. C. Grubelich; J. A. Romero; D. J. Staley; R. J. Buss; P. P. Ward; K. L. Erickson

1996-01-01

309

Experimental investigation on the thermal stability of some new zero ODP refrigerants  

Microsoft Academic Search

Five zero ODP (ozone depletion potential) hydro-fluorocarbon refrigerants (HFC-23, HFC-143a, HFC-227ea, HFC-236fa, HFC-245fa) were tested to define their maximum usable temperature and their thermal degradation threshold. Pyrolysis is detected (a) as a pressure change at constant temperature and volume; (b) as a departure of the vapour pressure curve of the heated fluid from that of the original substance. Visual inspection

Gianfranco Angelino; Costante Invernizzi

2003-01-01

310

Spatially resolved SiF and SiF2 densities in inductively driven discharges containing C2F6 and C4F8  

Microsoft Academic Search

Laser-induced fluorescence was used to measure the spatially resolved SiF and SiF2 radical densities in inductively driven discharges containing fluorocarbon gases. Measurements of the spatially resolved SiF and SiF2 densities were performed in C2F6 and C4F8 discharges as functions of the induction coil power, pressure, and bias power above a silicon surface. The SiF density had a maximum at a

G. A. Hebner

2001-01-01

311

CF, CF2, and SiF densities in inductively driven discharges containing C2F6, C4F8, and CHF3  

Microsoft Academic Search

Laser induced fluorescence was used to measure the spatially resolved CF, CF2, and SiF radical density in inductively driven discharges containing fluorocarbon gases. Measurements of the spatially resolved CF density were performed in C2F6, and CHF3 containing discharges as functions of inductive power, pressure and bias condition on a silicon substrate. In addition, CF rotational temperatures were calculated, assuming saturated

G. A. Hebner

2001-01-01

312

CF, CF2 and SiF densities in inductively driven discharges  

Microsoft Academic Search

Laser induced fluorescence was used to measure the spatially resolved CF, CF2 and SiF radical density in inductively driven discharges containing fluorocarbon gases. Measurements of the spatially resolved CF density were performed in C_2F6 and CHF3 containing discharges as functions of inductive power, pressure and bias condition on a silicon substrate. In addition, CF rotational temperatures were calculated, assuming saturated

Greg Hebner

2000-01-01

313

Degradation and crosslinking of perfluoroalkyl polyethers under X-ray irradiation in ultrahigh vacuum  

Microsoft Academic Search

Degradation of three types of commercially available perfluoroalkyl polyethers (PFPE)-Demnum S200, Fomblin Z25, and Krytox 16256-by X-ray irradiation was studied by using X-ray photoemission spectroscopy (XPS) and a mass spectrometer under ultra-high-vacuum conditions. The carbons in the polymers were characterized by chemical shifts of Cls binding energies. Gaseous products containing COF2 and low-molecular-weight fluorocarbons were formed. From Fomblin Z25, which

S. Mori; W. Morales

1989-01-01

314

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

Microsoft Academic Search

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

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

2009-01-01

315

New textile composite materials development, production, application  

NASA Technical Reports Server (NTRS)

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.

Mikhailov, Petr Y.

1993-01-01

316

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

Microsoft Academic Search

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 ~45

M. Schvartzman; S. J. Wind

2009-01-01

317

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

NASA Technical Reports Server (NTRS)

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.

Ross, B.; Parker, J.

1983-01-01

318

Performance of Carbon Black-Containing Polyurethane Foam in Domestic Refrigerators  

Microsoft Academic Search

The North American appliance industry has been challenged to meet stringent federal standards for energy consumption using CFC alternatives, which generally increase thermal conductivity of a foam. After a period of evaluating several options, the industry has, for the most part, settled on hydrochloro-fluorocarbon, HCFC-141b, as a substitute for CFC-11. Studies have shown that appliance foam systems using carbon black

J. S. Pisipati; J. A. Godbey

1996-01-01

319

Thermodynamic properties of perfluoro- n-octane  

Microsoft Academic Search

Fluorocarbons are attracting much attention nowadays because of their unique properties, which may provide interesting applications in areas as wide as environmental, biomedical and material science. However, the behavior of these compounds is not well understood and only scattered data can be found in the open literature and company technical reports.In this work, three important properties of perfluoro-n-octane were experimentally

A. M. A. Dias; A. I. Caço; J. A. P. Coutinho; M. M. Piñeiro; L. F. Vega; M. F. Costa Gomes; I. M. Marrucho

2004-01-01

320

Energetics and structures of fluoro- and chlorofluorocarbons in zeolites: Force field development and Monte Carlo simulations  

SciTech Connect

Canonical Monte Carlo simulations on the adsorption of a series of fluoro-, chlorofluoro-, and hydrofluorocarbons (CF{sub 4}, CF{sub 3}Cl, CF{sub 2}Cl{sub 2}, CFCl{sub 3}, CHF{sub 3}) in siliceous Y and NaY zeolites have been performed and are compared with available calorimetric data on the same host-guest systems. A new force field for fluorocarbon-type molecules in zeolites has been developed, and the (N,V,T) simulations predict adsorption heats with good accuracy. Further insights into the key features of host-guest interactions are gleaned from the relative contributions of the short-range and electrostatic interactions to the total adsorption heats and the analysis of host-guest pair functions. In siliceous Y, host-guest interactions are driven primarily by F{hor_ellipsis}O{sub zeolite} and Cl{hor_ellipsis}O{sub zeolite} van der Waals interactions, and H{hor_ellipsis}O{sub zeolite} hydrogen bonding in the case of hydrogen-containing fluorocarbons. When the fluorocarbon is adsorbed in a cation-containing zeolite, such as NaY, additional F{hor_ellipsis}Na{sub zeolite} electrostatic interactions with Na cations of the supercage are clearly revealed and control the orientation of the sorbate molecules within the supercages. In addition, (N,V,T) simulations have enabled us to compare the behavior of CHF{sub 3} with that of CHCl{sub 3}. The heats of adsorption at zero loading are very similar, but the relative contributions of the short-range and long-range interactions are inverted between the two systems, with the electrostatic term dominating in the case of the fluorocarbon.

Mellot, C.F. [Univ. de Versailles Saint-Quentin (France). Inst. Lavoisier] [Univ. de Versailles Saint-Quentin (France). Inst. Lavoisier; Cheetham, A.K. [Univ. de Versailles Saint-Quentin (France). Inst. Lavoisier] [Univ. de Versailles Saint-Quentin (France). Inst. Lavoisier; [Univ. of California, Santa Barbara (Canada). Materials Research Lab.

1999-05-13

321

Solubility behavior of ethyl cellulose in supercritical fluid solvents  

Microsoft Academic Search

Solubility data to 180°C and 1200 bar are reported for ?1.0 wt.% ethyl cellulose (50% ethoxyl content, 2.5 average degree of substitution) (EC) in neat supercritical fluid (SCF) chlorodifluoromethane (F22); difluoromethane; 1-chloro-1,1-difluoroethane; 1,1-difluoroethane; and dimethyl ether (DME). The pressures needed to dissolve EC in the polar fluorocarbons decreases with increasing solvent size. The exception in this trend is F22 which

Dan Li; Mark A. McHugh

2004-01-01

322

Polymeric and composite materials for use in systems utilizing hot, flowing geothermal brine. II  

Microsoft Academic Search

Further progress is reported on a continuing experimental program designed to select high-performance polymeric materials for use in geothermal power plants. In field tests 12 nozzles, 27 wear plates, and 2 types of polymer lined pipe were tested. Nozzles made of Teflons TFE and PFA, Tefzel, Ryton PPS and H-Resin\\/carbon cloth were little changed except for some scaling. The fluorocarbons

L. E. Lorensen; C. M. Walkup

1978-01-01

323

Experimental observations of hydrate formation in a convection tank  

Microsoft Academic Search

Clathrate hydrates (generally abbreviated to hydrates) are crystalline compounds formed by cage-like structure of hydrogen-bonded water molecules enclosing a guest molecule of a hydrate-forming substance. Many substances such as gases and fluorocarbon refrigerants are hydrate formers. Priestly first made hydrates in water saturated with SO2 gas at 7°C in 1778. Hydrates became industrially important in 1930's when their formation caused

C. F. Chen; Cho Lik Chan

2003-01-01

324

Fabrication of PDMS stamps for the patterned growth of carbon nanotubes  

Microsoft Academic Search

An anti-adhesion coating technique has been developed for the defect-free release of patterned polydimethylsiloxane (PDMS) stamps. The coating of the anti-adhesion layer involves the use of a C4F8 (octafluorocyclobutane) plasma to deposit a thin fluorocarbon film on the surface of the silicon (Si) print masters in an inductively coupled plasma system. The fabrication method for the defect-free PDMS stamps using

P. Argyrakis; L. Teo; T. Stevenson; R. Cheung

2005-01-01

325

Solubility and diffusivity of 1,1,1,2-tetrafluoroethane in room-temperature ionic liquids  

Microsoft Academic Search

The solubility and diffusivity of 1,1,1,2-tetrafluoroethane (R-134a) in seven room-temperature ionic liquids (RTILs) are presented. Among them, five of the RTILs were prepared for the first time with three new fluorocarbon sulfonate anions, and two were commercially available (1-butyl-3-methylimidazolium hexafluorophosphate was previously studied with R-134a). The gas absorption measurements were made using a gravimetric microbalance. Four isotherms (283.15, 298.15, 323.15,

Mark B. Shiflett; Mark A. Harmer; Christopher P. Junk; A. Yokozeki

2006-01-01

326

Dry Etching of SiO2 Thin Films with Perfluoropropenoxide-O2 and Perfluoropropene-O2 Plasmas  

Microsoft Academic Search

In this work, the plasma etching characteristics of SiO2 thin films have been investigated using RF glow discharges fed with C3F6O and C3F6 mixted with oxygen. The results have been compared with performances obtained with CF4-CHF3 gases. The research was aimed at studying the utilization of new fluorocarbons in SiO2 plasma etching with a low impact on global warming. The

Francesco Fracassi; Riccardo D'Agostino; Antonella Fornelli; Tatsuru Shirafuji

2002-01-01

327

Removal of C2F6 from a semiconductor process flue gas by a ferroelectric packed-bed barrier discharge reactor with an adsorber  

Microsoft Academic Search

The abatement of greenhouse gases from semiconductor processes is becoming important. Methane and\\/or nitrous oxide are continuously exhausted from the processes, and high concentrations of per-fluorocarbons (PFCs), such as NF3, C2F6 , SF6, and CF4, are exhausted during wafer etching and clean up of PECVD (plasma enhanced chemical vapor deposition) chambers. The removal of C2F6 from a simulated semiconductor-process flue

Kuniko Urashima; Konstantin G. Kostov; Jen-Shih Chang; Y. Okayasa; Takashi Iwaizumi; Kazunari Yoshimura; Tadao Kato

2001-01-01

328

Amorphous Silicon and Tungsten Etching Employing Environmentally Benign Plasma Process  

Microsoft Academic Search

A novel dry etching process for amorphous silicon (a-Si) and tungsten (W) for chemical vapor deposition (CVD) chamber cleaning has been performed by electron cyclotron resonance (ECR) O2 plasma employing a solid-material evaporation system where fluorocarbon species are produced from fluorinated ethylene propylene (FEP) by CO2 laser evaporation for preventing global warming. This process enables us to realize etching of

Kazushi Fujita; Shigeto Kobayashi; Masafumi Ito; Masaru Hori; Toshio Goto

2001-01-01

329

General Chemistry Division. Quarterly report, October-December 1979  

SciTech Connect

Progress is reported on analytical R and D for the nuclear explosives programs (coupling of gas chromatograph, mass spectrometer, and infrared spectrometer; analysis of fluorocarbon FC-86; far-infrared laser development; transient behavior of n-type TiO/sub 2/ semiconductor photoelectrodes; and impurities on Kevlar 49 fibers) and for the energy programs (on-line mass spectroscopy of oil shale and testing of additives for controlling the scaling of hypersaline geothermal brine). (DLC)

Not Available

1980-02-15

330

Conformational and orientational order and disorder in solid polytetrafluoroethylene  

Microsoft Academic Search

The low pressure phase diagram of solid polytetrafluoroethylene (PTFE\\/Teflon) has been investigated using constant temperature-constant pressure molecular dynamics techniques and a new all-atom potential model for fluorocarbons. The simulation was started in an ordered low temperature phase in which the molecules are parallel and have a helical conformation with a pitch of uniform magnitude and sign (chirality). In accordance with

Michiel Sprik; Ursula Rothlisberger; Michael L. Klein

1999-01-01

331

210. Die Wirkung eines Sauerstoffträgers bei der initialen Perfusion von Extremitäten vor Replantation. Metabolische und hämodynamische Parameter im Tierexperiment  

Microsoft Academic Search

Summary As previously shown in rabbits (amputation of hind legs, 4-h storage at 4 °C, 30-min perfusion, 2-h recirculation), an initial perfusion with fluorocarbon (FC) emulsion (FC-43, Pfrimmer, Erlangen) improves the starting conditions for the replantation of extremities (Langenbecks Arch Chir 355: 651, 1981). In order to evaluate the specific O2 carrier (perfluorotributylamine) effects, we compared FC-43 to its FC-free

G. Richt; P. Wendt; I. Wölfl; I. Vassiliou; Th. u Mittelmeier; G. Blümel

1984-01-01

332

Thermoresponsive viscoelasticity of concentrated solutions with a fluorinated hybrid surfactant  

Microsoft Academic Search

Temperature-dependent viscosity of an aqueous solution of sodium 1-oxo-1-[4-(tridecafluorohexyl)phenyl]-2-hexanesulfonate (FC6-HC4), a fluoro-hybrid type surfactant, which has a fluorocarbon chain and a hydrocarbon chain in a molecule, was examined. The FC6-HC4 solution showed viscoelastic behavior at concentrations around 10 wt.%. Further study on the temperature dependence of the viscosity of a 10 wt.% solution revealed that the viscosity increased about 102

Masahiko Abe; Kazuhiko Tobita; Hideki Sakai; Keiji Kamogawa; Nobuyuki Momozawa; Yukishige Kondo; Norio Yoshino

2000-01-01

333

Studies identify problems and strengths of collector seals and sealing compounds  

SciTech Connect

Results of an extensive literature search and accelerated testing of elastomers used for preformed seals and sealing compounds in solar collectors are summarized. Data include compression set thermal aging data, sealant outgassing test results, and the effect of glaze deposits on relative light transmittance. The preformd seals and sealing compounds recommended are fluorocarbons for high temperature, and silicones, acrylics, acrylic copolymers and EPDMs for intermediate temperature. (LEW)

Not Available

1981-08-01

334

Pretreatment of Kapton-coated cable for epoxy adhesion  

SciTech Connect

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.

Carley, J.F.

1984-01-09

335

Roughness and chemistry of silicon and polysilicon surfaces etched in high-density plasma: XPS, AFM and ellipsometry analysis  

NASA Astrophysics Data System (ADS)

Surface chemistry and morphology of polysilicon thin films etched in a high-density fluorocarbon plasma under various conditions are studied by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and spectroscopic ellipsometry. XPS reveals the presence of a fluorocarbon layer, which composition and thickness depend on the plasma conditions. Ellipsometry measurements show the need to consider the superficial roughness. Surface roughness and morphology obtained by AFM are used to define geometric models suitable to represent the top layer when processing the ellipsometry data. Results are discussed and compared to that given by the Bruggeman effective medium approximation (BEMA). The BEMA model always agrees with the geometric model, which is the closest to the observed surface morphology. However, if a good agreement is obtained between surface roughness and top layer thickness for unetched or weakly damaged samples, a discrepancy is observed for the etched samples. Formation of a non-transparent fluorocarbon layer on these sample is put forward to explain this behaviour.

Rolland, Laëtitia; Vallée, Christophe; Peignon, Marie-Claude; Cardinaud, Christophe

2000-09-01

336

Detection of Chamber Conditioning Through Optical Emission and Impedance Measurements  

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

337

Plasma chemical behaviour of reactants and reaction products during inductively coupled CF4 plasma etching of SiO2  

NASA Astrophysics Data System (ADS)

A two-dimensional fluid model has been developed to study plasma chemical behaviour of etch products as well as reactants during inductively coupled CF4 plasma etching of SiO2. The plasma fluid model consisted of Maxwell's equations, continuity equations for neutral and charged species including gas-phase and surface reactions and an energy balance equation for electrons. The surface reaction model assumed Langmuir adsorption kinetics with the coverage of fluorine atoms, fluorocarbon radicals and polymers on SiO2 surfaces. Numerical results indicated that etch product species occupy a significant fraction of reactive ions as well as neutrals in the reactor chamber during etching, which in turn leads to a change in plasma and surface chemistry underlying the processing. In practice, the density of SiF4 was typically about 10% of that of the feedstock CF4, being comparable to that of the most abundant fluorocarbon radical CF2; moreover, the density of SiF_3^+ was typically about 5% of that of the most abundant fluorocarbon ion CF_3^+ . The density and the distribution of such product species in the reactor chamber were changed by varying the ion bombardment energy on the substrate surfaces, gas pressure, mass flow rate and coil configuration, which arises in part from gas-phase reactions depending on plasma electron density and temperature. Surface reactions on the chamber walls and on the substrate also affect the product density and distribution in the reactor; in particular, the surface reactions on the SiO2 dielectric window as well as substrate surfaces were found to largely affect the product density and distribution.

Fukumoto, Hiroshi; Fujikake, Isao; Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi

2009-11-01

338

Interaction of alcohols and ethers with a-CF(x) films.  

PubMed

The surfaces of the magnetic data storage hard disks used in computers are coated with a thin film of amorphous carbon and a layer of perfluoropolyalkyl ether (PFPE) lubricant. Both protect the surface of the magnetic layer from contact with the read-write head flying over the disk surface. Although the most commonly used carbon films are amorphous hydrogenated carbon, a-CH(x), it has been suggested that the thermal properties of amorphous fluorinated carbon films, a-CF(x), might be superior. This work has probed the interaction of small fluorinated ethers and alcohols with the surfaces of a-CF(x) films to understand the effects of carbon film fluorination on the interaction of the lubricant with its surface. Temperature-programmed desorption was used to measure the desorption energies of small fluorocarbons from the a-CF(x) surface and to compare their desorption energies with those from the surfaces of a-CH(x) films. These measurements reveal that, similarly to a-CH(x) films, a-CF(x) films expose a heterogeneous surface on which fluorocarbons adsorb at sites with a range of binding energies. The fluorocarbon ethers all have lower heats of adsorption than their hydrocarbon counterparts, suggesting that the ethers adsorb by donation of electron density from the oxygen lone-pair electrons to sites on the surface. Fluorinated alcohols have roughly the same heats of adsorption as their hydrocarbon counterparts. There is little significant difference between the interactions of fluorinated ethers (or alcohols) with the surfaces of either a-CF(x) or a-CH(x) films. PMID:16430269

Lim, Min Soo; Yun, Yang; Gellman, Andrew J

2006-01-31

339

C-H/?-interaction-guided self-assembly in ?-conjugated oligomers.  

PubMed

We report CH/? hydrogen-bond-driven self-assembly in ?-conjugated skeletons based on oligophenylenevinylenes (OPVs) and trace the origin of interactions at the molecular level by using single-crystal structures. OPVs were designed with appropriate pendants in the aromatic core and varied by hydrocarbon or fluorocarbon tails along the molecular axis. The roles of aromatic ?-stack, van der Waals forces, fluorophobic effect and CH/? interactions were investigated on the theromotropic liquid crystallinity of OPV molecules. Single-crystal structures of hydrocarbon OPVs provided direct evidence for the existence of CH/? interactions between the ?-ring (H-bond acceptor) and alkyl C-H (H-bond donor). The four important crystallographic parameters, d(c-x)=3.79 Å, ?=21.49°, ?=150.25° and d(Hp-x)=0.73 Å, matched in accordance with typical CH/? interactions. The CH/? interactions facilitate the close-packing of mesogens in x-y planes, which were further protruded along the c axis producing a lamellar structure. In the absence of CH/? interactions, van der Waals interactions drove the assembly towards a Schlieren nematic texture. Fluorocarbon OPVs exhibited smectic liquid-crystalline textures that further underwent Smectic A (SmA) to Smectic C (SmC) phase transitions with shrinkage up to 11%. The orientation and translational ordering of mesogens in the liquid-crystalline (LC) phases induced H- and J-type molecular arrangements in fluorocarbon and hydrocarbon OPVs, respectively. Upon photoexcitation, the H- and J-type molecular arrangements were found to emit a blue or yellowish/green colour. Time-resolved fluorescence decay measurements confirmed longer lifetimes for H-type smectic OPVs relative to that of loosely packed one-dimensional nematic hydrocarbon-tailed OPVs. PMID:22298381

Goel, Mahima; Jayakannan, Manickam

2012-03-01

340

Physicochemical properties of oleic acid-based partially fluorinated gemini surfactants.  

PubMed

We have developed oleic acid-based partially fluorinated gemini surfactants with carboxylic acid headgroups. The fluorocarbon chain is covalently bound to the terminal carbonyl group of oleic acid via a -CH(2)CH(2)OCO- unit, and the carboxylic acid headgroups are introduced to the cis double bond of oleic acid via -OCOCH(2)CH(2)- units. The aqueous solution properties of these surfactants were studied at pH 9 in the presence of 10 mmol dm–3 NaCl by means of static surface tension, pyrene fluorescence, and dynamic light scattering measurements. The resulting surface tension data demonstrate that the partially fluorinated gemini surfactants exhibit excellent surface activity in their dilute aqueous solutions. In addition, the surfactants are suggested to form micellar aggregates 2–4 nm in diameter. We also studied the aqueous temperature-concentration phase diagrams of the partially fluorinated gemini surfactants (disodium salts) on the basis of visual observations (through a crossed polarizer), polarized optical microscopy, and small angle X-ray scattering measurements. Several phase states including micellar solution phase, hexagonal phase, bicontinuous cubic phase, and lamellar phase were observed along with the coexistence of these phases in certain regions. Assemblies with lesser positive curvature tend to be formed with increasing surfactant concentration, increasing temperature, and increasing fluorocarbon chain length. A comparison of the phase diagrams of the partially fluorinated and hydrogenated surfactant systems suggests that close molecular packing is inhibited within the assemblies of the partially fluorinated surfactants because of the limited miscibility between the fluorocarbon and hydrocarbon units. To the best of our knowledge, this is the first systematic report focusing on the temperature-concentration phase diagrams of (partially) fluorinated gemini surfactants over a wide range of compositions and temperatures. PMID:24712085

Sakai, Kenichi; Umemoto, Naoki; Aburai, Kenichi; Takamatsu, Yuichiro; Endo, Takeshi; Kitiyanan, Boonyarach; Matsumoto, Mutsuyoshi; Sakai, Hideki; Abe, Masahiko

2014-01-01

341

Kinetics of the Reactions Involving CF2 and CF in a Pure Tetrafluoromethane Plasma: I. Production of CF2 and CF via Electron-Impact Dissociation  

NASA Astrophysics Data System (ADS)

The kinetics of the production and loss of CF2 and CF radicals in a glow discharge in pure CF4 is investigated by the laser-induced fluorescence method. The effective rate constants for electron-impact dissociation of CF4 molecules along the pathways toward CF2 and CF radicals are determined within a wide range of the reduced electric field (80-250 Td). It is shown that, along with the direct electron-impact dissociation of CF4, the radicals are also produced via the dissociation of the CxFy polymer fluorocarbon particles that form in the plasma. A detailed analysis of the kinetics of the radical production and loss in a modulated discharge made it possible to evaluate the contribution of the electron-impact dissociation of CF4 to the production of radicals and, consequently, to determine the dissociation rate constants k_{CF_2 } and k CF. A comparison of the obtained k_{CF_2 } and k CF values with the results of calculations by the Monte Carlo method and the literature data on the cross sections for electron-impact dissociation of CF4 molecules enabled the normalization of these cross sections in the threshold region and the construction of the model cross sections for the electron-impact dissociation of CF4 into neutral products. The calculated cross sections allow a satisfactory description of the experimental results throughout the entire range of E/N under study. A significant scatter (up to 100%) in the experimental data on k_{CF_2 } and k CF at low values of E/N is related to the considerable contribution of the CxFy polymer molecules (and, probably, CxF{y/+} ions and fluorocarbon grains) to the production of CF2 and CF radicals both in the plasma volume and on the surface of a fluorocarbon film covering the discharge tube wall.

Ivanov, V. V.; Klopovskii, K. S.; Lopaev, D. V.; Proshina, O. V.; Rakhimov, A. T.; Rakhimova, T. V.; Rulev, G. B.

2002-03-01

342

Spectroscopic study of gas and surface phase chemistries of CF{sub 4} plasmas in an inductively coupled modified gaseous electronics conference reactor  

SciTech Connect

Gas and surface phase chemistries of CF{sub 4} plasma were studied in an inductively coupled modified gaseous electronics conference reference cell, using in situ Fourier transform infrared spectroscopy enhanced by a multipass White cell and in situ spectroscopic ellipsometry. The self-bias dc voltage, densities of gaseous species, fluorocarbon film thickness on Si substrate, as well as etch rates of SiO{sub 2} and Si were measured during plasma processing as functions of the pressure, CF{sub 4} gas flow rate, rf source power, platen bias power, and source-platen gap. The gaseous molecules and radicals monitored included CF{sub 4}, CF{sub 3}, CF{sub 2}, SiF{sub 4}, and COF{sub 2}, among which CF{sub 4} and SiF{sub 4} were found to be the two dominant species, combining for about 80% of the total concentration. The density ratio of SiF{sub 4} and COF{sub 2} was about 2:1 with no bias on the substrate and increased up to {approx}8:1 when Si substrate etching took place. Specifically, as the Si etch rate increased, the COF{sub 2} density dropped, likely due to suppressed etching of the quartz source window, while the density of SiF{sub 4} increased. Comparisons between the gas phase data and etch rate results of Si and SiO{sub 2} indicate that the gas phase chemistry is strongly influenced by surface reactions on the substrate, wall, and quartz source window. The thickness of fluorocarbon reaction layer on Si substrate is mainly determined by densities of fluorocarbon radicals and fluorine atoms in the bulk plasma as well as the self-bias voltage on the substrate, and a thicker film is usually associated with a lower etch rate.

Zhou Baosuo; Joseph, Eric A.; Overzet, Lawrence J.; Goeckner, Matthew J. [Department of Electrical Engineering, University of Texas at Dallas, Richardson, Texas 75083 (United States)

2006-01-15

343

Structural and electrochemical characterization of a cerium(IV) hydroxamate complex: implications for the beneficiation of light rare earth ores.  

PubMed

Reaction of N-phenyl-pivalohydroxamic acid with Ce(III) precursors leads to a homoleptic hydroxamate complex: Ce(IV)[(t)BuC(O)N(O)Ph]4. Electrochemical experiments indicate a significant stabilization of the Ce(IV) cation at Ep,c = -1.20 V versus SCE in the hydroxamate ligand framework. The spontaneous oxidation of Ce(III) in a hydroxamate ligand field is discussed in the context of beneficiation of the light rare earths from the fluorocarbonate mineral bastnäsite. PMID:24177048

Lee, Heui Beom; Bogart, Justin A; Carroll, Patrick J; Schelter, Eric J

2014-05-25

344

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

DOEpatents

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.

Martinez, Robert J. (Albuquerque, NM); Rye, Robert R. (Albuquerque, NM)

1991-01-01

345

Sealants for solar collectors  

SciTech Connect

Elastomeric sealants employed in thermal solar collectors are subjected to extremely harsh conditions. In order to function properly for long periods of time, they must exhibit good resistance to environmental factors such as high and low temperature extremes, oxygen, ozone, water, and ultraviolet radiation. Several types of candidate elastomers consisting of fluorocarbon, silicone, acrylic, ethylene-acrylic, ethylene-propylene terpolymer, and butyl and chlorosulfonated polyethylene were subjected to extensive testing. Results are reported on outgassing characteristics during thermal aging and on retention of such physical properties as compression set, elongation, and tensile strength. Relative hydrolytic stabilities of these materials are also discussed. 1 ref.

Mendelson, M.A.; Luck, R.M.; Yeoman, F.A.; Navish, F.W. Jr.

1981-09-01

346

A New Energy-Efficient and Environmentally Friendly Process to Produce Aluminum  

NASA Astrophysics Data System (ADS)

The Hall-Heroult process to produce aluminum is more than 125 years old. Larger, more efficient cells have been developed, and process control has improved, but the process is basically unchanged. A new process has been under development since 1990 that promises 20% lower capital cost and 20% lower operating cost and no CO2 or fluorocarbon emissions. A new cell design, new anode and cathode materials, new electrolyte, and new operating conditions are based on experience over the past six decades. The evolution of this technology to its present state is described here.

Beck, T. R.

2013-02-01

347

Factors affecting the sticking of insects on modified aircraft wings  

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

348

Nanoheterogeneous multilayer films with perfluorinated domains fabricated using the layer-by-layer method.  

PubMed

Nanoheterogenous ultrathin films containing perfluorinated domains were prepared via the layer-by-layer (LbL) electrostatic self-assembly method. The films are constructed from the amphiphilic cationic copolymer with perfluorinated side chains and poly(sodium styrenesulfonate) (PSS). The LbL process was optimized by the application of sonication which allowed linear growth of the film. The resulting film exhibited micellar structure with isolated fluorocarbon hydrophobic domains. The remarkable features of the films were their switchable wettability and friction properties. The obtained water-processable films can find a number of potential applications, e.g., as smart and low friction coatings. PMID:20527832

Niemiec, Wiktor; Zapotoczny, Szczepan; Szczubia?ka, Krzysztof; Laschewsky, André; Nowakowska, Maria

2010-07-20

349

Temperature dependent sensor response caused by polymer-solvent interactions  

SciTech Connect

Absorption of organic solvents by a range of polymers has been used as the chemical transduction mechanism for a variety of sensors. This paper examines the effect of the polymer-solvent interaction on the temperature dependence of the sensor response. Optical interferometric cavities are formed on the end of an optical fiber by plasma-deposition of a fluorocarbon polymer. Swelling of the polymer when exposed to various solvent vapors produces changes in the reflectivity of the fiber tip. The temperature dependence of the sensor response is related to the strength of the polymer-solvent interaction and the heat of vaporization of the solvent.

Butler, M A

1992-01-01

350

Downstream electron beam exciter diagnostic with energy dependent cross section responses for process tool applications  

NASA Astrophysics Data System (ADS)

Optical emission spectroscopy (OES) still remains as the primary diagnostic in plasma process tools in micro-electronics industry. With newer plasma processes and detection demands in low open area etches, process monitoring with direct optical signals is severely limited. Here we present a diagnostic method that realizes optical signals due to an electron beam from an inductively coupled plasma. Distinct merits such as energy dependent optical emission cross section responses and stable operability in polymerizing / corrosive etch environments will be presented. Electron impact optical cross section responses of transitions in fluorocarbon, oxygen and inert gas chemistries will be shown. Such controllability, in the context of species density measurement will be discussed.

Thamban, P. L. Stephan; Padron Wells, Gabriel; Hosch, Jimmy; Goeckner, Matthew

2011-10-01

351

Trifluoroacetate in the environment. Evidence for sources other than HFC\\/HCFCs  

Microsoft Academic Search

The partly halogenated Câ-hydro(chloro)fluorocarbons (HFC, HCFC) 1,1,1-trifluoro-2,2-dichloroethane (HCFC-123), 1,1,1,2-tetrafluoro-2-chloroethane (HCFC-124), and 1,1,1,2-tetrafluoroethane (HFC-134a) are CFC substitutes found at increasing levels in the atmosphere. Trifluoroacetate (TFA) is an atmospheric degradation product of these compounds and due to its persistence its potential accumulation in some aquatic ecosystems is a matter of environmental concern. The present study was undertaken to determine the present-days

Armin Jordan; Hartmut Frank

1999-01-01

352

The effect of the rigidity of perfluoropolyether surfactant on its behavior at the water/supercritical carbon dioxide interface.  

PubMed

We performed a series of molecular dynamics simulations to study the PFPE (perfluoropolyether) and PE (polyether) surfactant monolayers at the water/supercritical carbon dioxide interface. Molecular differences between fluorocarbon surfactant PFPE and its hydrocarbon analogue PE were analyzed. We observed that values of intramolecular bonded interaction parameters which are related to chain rigidity determine the monolayer surface pressure. We show that "good" and "bad" properties of PFPE/PE surfactants are connected to conformational entropy. These results are consistent with our previous micellar simulations. PMID:16853822

Lu, Lanyuan; Berkowitz, Max L

2005-11-24

353

Atomic Resolution Images of Solid-Liquid Interfaces  

NASA Astrophysics Data System (ADS)

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.

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

354

Telemetry engineering and fabrication alternative soldering techniques for CFC elimination  

SciTech Connect

In an effort to eliminate the need for chlorinated fluorocarbons (CFCs) for several production assemblies in Telemetry Engineering and Fabrication, an alternate soldering reflow process to replace the current vapor phase system was needed. After analyzing IR, convection, and recovery vapor phase soldering reflow methods, it was discovered that an improved process would result from the implementation of a new convection reflow system. The convection oven reflow method was evaluated by collecting data from visual inspections, shear, push, and cross-section tests on several surface mount devices.

Howard, R.V.

1995-08-01

355

Residential application of refrigerant-charged solar collectors  

NASA Astrophysics Data System (ADS)

A fluorocarbon (trichlorofluoromethane) loaded solar collector system was installed and evaluated. It demonstrated 83 percent energy recovery at a low collector temperature difference of approximately 10 C. The maximum peak energy picked up by the collector surface was 2.8 MJ/sq m-hr (250 Btu/hr-sq ft). The heat-transfer medium is relatively nontoxic, noncorrosive and nonfreezing in cold climates. In this application it circulates by natural convection; therefore, the system requires no pump or electronic control in the primary loop.

Schreyer, J. M.

356

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)

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.

Popovic, V.

1973-01-01

357

Study of plasma - surface interactions: chemical dry etching and high-density plasma etching  

NASA Astrophysics Data System (ADS)

We report results of the characterization of the plasma - surface interactions of silicon and silicon dioxide in fluorocarbon discharges using real-time ellipsometry and post-plasma multi-technique surface analysis for chemical dry etching (CDE) and high-density plasma etching (HDPE). We show that changes of the gas composition in CDE causes major changes in silicon surface chemistry and etching behaviour. For low-pressure HDPE we investigate the influence of power deposition into the discharge and bias voltage and bias power at the wafer on the surface chemical changes of silicon and 0963-0252/5/2/012/img1.

Oehrlein, G. S.; Matsuo, P. J.; Doemling, M. F.; Rueger, N. R.; Kastenmeier, B. E. E.; Schaepkens, M.; Standaert, Th; Beulens, J. J.

1996-05-01

358

Mass spectrometric studies of the electrical breakdown of thin polymer films  

NASA Technical Reports Server (NTRS)

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.

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

1986-01-01

359

Robust Cu Dual Damascene Interconnects With Porous SiOCH Films Fabricated by Low-Damage Multi-Hard-Mask Etching Technology  

Microsoft Academic Search

Low-damage hard-mask (HM) plasma-etching technology for porous SiOCH film (k=2.6) has been developed for robust 65-nm-node Cu dual damascene interconnects (DDIs). No damage is introduced by fluorocarbon plasma etching irrespective of whether rigid (k=2.9) or porous (k=2.6) SiOCH films are used, due to the protective CF-polymer layer deposited on the etched sidewall. The etching selectivity of the SiOCH films to

Hiroto Ohtake; Masayoshi Tagami; Munehiro Tada; Makoto Ueki; Mari Abe; Shinobu Saito; Fuminori Ito; Yoshihiro Hayashi

2006-01-01

360

Reactions of laser-generated free radicals at semiconductor surfaces  

NASA Astrophysics Data System (ADS)

Reactions of laser generated free radicals at semiconductor surfaces were investigated by photoelectron spectroscopy of adsorbed surface layers and by laser induced fluorescence detection of the gas-phase species. Systems investigated include dissociative chemisorption of XeF2 and CF3 on Si (111), IR multiple photon dissociation of alkylsilanes and characterization of the SiH2 dissociation product and deposition of metallic films from iron carbonyl. From these experiments, quantitative models were developed for the reactivity of fluorocarbon radicals at silicon surfaces, intersystem state coupling in excited SiH2, and formation of metallic films.

Steinfeld, Jeffrey I.

1990-01-01

361

Organic fluorides: implications for psychiatry.  

PubMed

The widespread use of synthetic organic fluorides has recently received attention as a potential health hazard. There are a number of organic fluorides which have become important considerations in psychiatry. Therapeutically the organic fluorides include the neuroleptics trifluoperazine, fluphenazine, triflupromazine, and haloperidol, the benzodiazepine flurazepam and the polyfluorinated inhalant convulsant indoklon. On the negative side, deliberate inhalation of fluorocarbon aerosol propellants has become a modern form of drug abuse among the young. A review is presented on the biochemistry and toxicology of organic fluorides with special emphasis on implications to the field of psychiatry. PMID:26669

Guynn, R W; Faillace, L A

1978-06-01

362

Energy distribution of bombarding ions in plasma etching of dielectrics  

NASA Astrophysics Data System (ADS)

In plasma etching for microelectronics fabrication, a sheath electric field accelerates ions into the substrate so they strike at normal incidence, contributing energy and reactive species to enable anisotropic etch profiles. The energy of the bombarding ions is typically controlled coarsely with a sinusoidal bias voltage applied to the substrate electrode, producing a broad bimodal ion energy distribution (IED) at the substrate. By systematically tailoring the shape of the waveform, the energies and relative fluxes of the two IED peaks are varied independently over a 100-500 eV range in a fluorocarbon-based helicon plasma, while silicon dioxide and photoresist etch rates are monitored. A 100 eV IED peak was combined with a higher energy peak, with the energy and relative flux of the high energy group as variables in the experiment. A relatively small contribution of high energy ions is found to lead to considerable etch rate enhancement, higher than predicted by a linear combination of single-peak etch rates at the two energies. Because high energy ion bombardment is known to suppress fluorocarbon deposition, it seems likely that changes in surface chemical composition in their presence enhances the contribution of lower energy ions to etching reactions.

Buzzi, F L; Ting, Y-H; Wendt, A E

2009-05-01

363

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

SciTech Connect

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.

Kaufman, J.D.; Morgan, M.S.; Marks, M.L.; Greene, H.L.; Rosenstock, L. (Department of Medicine, University of Washington, Seattle (United States))

1992-01-01

364

Synthesis and characterization of self-assembling water-soluble polymers  

SciTech Connect

The synthesis is proposed of water-soluble vinyl and other polymers capable of self-assembly through hydrophobic bonding of pendent fluorocarbon and other hydrophobic groups. The self-assembly process will be studied by viscometry and dynamic viscoelasticity, and by static and dynamic light scattering. These investigations are aimed at identifying the structural features of polymers that are important in enhancing the viscosity of aqueous polymer solutions at very low polymer concentrations (< 1,000 ppm). The authors also initiate small angle neutron scattering (SANS) measurements aimed at the determination of the size of the fluorocarbon-containing hydrophobic aggregates. They will be interested in the degree of self assembly as a function of the type and length of the hydrophobic groups and of the type and length of the flexible spacer group linking the hydrophobic to the polymer backbone. The nature of the hydrophilic chain will also be of interest. Thus, they investigate a number of hydrophilic comonomers such as acrylamide, N-vinylpyrrolidone and anionic or cationic vinyl monomers. Surface interactions of these interesting copolymers will be studied by adsorption onto appropriate modified latex spheres. Finally, they propose to explore the synthesis of water-soluble polymers capable of self assembly through interactions of pendent polyanions and polycations.

Hogen-Esch, T.E.; Amis, E.J.

1992-05-01

365

Surface mobility and slip of polybutadiene melts in shear flow  

SciTech Connect

Surface mobility and wall slip of entangled polybutadiene melts were studied with attenuated-total-reflectance infrared spectroscopy at stresses characteristic of the sharkskin, spurt, and melt-fracture regimes. Small-scale slip, accompanied by an apparent decrease in transverse mobility, occurs in the sharkskin regime, but at a stress above the visual onset of sharkskin in capillary viscometry. Simulations cannot distinguish between a cohesive mechanism and a lubrication mechanism that might follow from a stress-induced phase transition, but an adhesive failure seems to be excluded. The near-surface length scale is of the order of four to six times the equilibrium root-mean-square end-to-end distance, and the estimated slip velocity is insensitive to molecular weight. Strong slip occurs in the spurt regime, either at the wall or within one radius of gyration. Substantial apparent slip occurs with a fluorocarbon surface, but the mechanism does not appear to be an adhesive failure; there seems to be a substantial decrease in the friction coefficient of chains over a distance of order 300 nm or more from the fluorocarbon surface, and the transverse chain mobility in this region appears to be enhanced rather than retarded. Overall, the results of this study indicate that the influence of the wall extends farther into the sheared melt than would be expected from the chain dimensions, except in the case of strong slip. (c) 2000 Society of Rheology.

Wise, Geoffrey M. [Materials Sciences Division, Lawrence Berkeley National Laboratory, and Department of Chemical Engineering, University of California, Berkeley, California 94720-1462 (United States)] [Materials Sciences Division, Lawrence Berkeley National Laboratory, and Department of Chemical Engineering, University of California, Berkeley, California 94720-1462 (United States); Denn, Morton M. [Materials Sciences Division, Lawrence Berkeley National Laboratory, and Department of Chemical Engineering, University of California, Berkeley, California 94720-1462 (United States)] [Materials Sciences Division, Lawrence Berkeley National Laboratory, and Department of Chemical Engineering, University of California, Berkeley, California 94720-1462 (United States); Bell, Alexis T. [Materials Sciences Division, Lawrence Berkeley National Laboratory, and Department of Chemical Engineering, University of California, Berkeley, California 94720-1462 (United States)] [Materials Sciences Division, Lawrence Berkeley National Laboratory, and Department of Chemical Engineering, University of California, Berkeley, California 94720-1462 (United States); Mays, Jimmy W. [Department of Chemistry, University of Alabama, Birmingham, Alabama 35294 (United States)] [Department of Chemistry, University of Alabama, Birmingham, Alabama 35294 (United States); Hong, Kunlun [Department of Chemistry, University of Alabama, Birmingham, Alabama 35294 (United States)] [Department of Chemistry, University of Alabama, Birmingham, Alabama 35294 (United States); Iatrou, Hermis [Department of Chemistry, University of Alabama, Birmingham, Alabama 35294 (United States)] [Department of Chemistry, University of Alabama, Birmingham, Alabama 35294 (United States)

2000-05-01

366

Controlling phospholipid self-assembly and film properties using highly fluorinated components--fluorinated monolayers, vesicles, emulsions and microbubbles.  

PubMed

Use of fluorinated components instead or along with standard phospholipids in film, vesicle, bubble and emulsion engineering, can cause drastic modifications of the formation processes, structure and dynamics, and functional behavior of these systems. Perfluoroalkyl chains provide a powerful driving force for self-assembly and ordering. They allow, for example, obtainment of thermally stable vesicles from single-chain phosphocholine derivatives, tubules from non-chiral amphiphiles, faceted vesicles with fluid bilayer membranes, exceptionally stable and narrowly dispersed emulsions and microbubbles. Contact of a monolayer of DPPC with a fluorocarbon gas modifies the monolayer's phase behavior, suppressing the liquid expanded/liquid condensed transition. Phospholipid absorption kinetics at an air/water interface can be substantially accelerated, and the equilibrium interfacial tension reduced by exposure to a fluorocarbon gas. Perfluoroalkyl chains induce nanocompartmentation in films and membranes, allowing, for example, polymerization within vesicular membranes. Vesicles involving highly fluorinated components generally exhibit stability, permeability, fusion and recognition characteristics, different from those of their hydrogenated analogues. Drastic stabilization can be gained for phospholipid-coated emulsions through a co-surfactant effect of (perfluoroalkyl)alkyl diblocks. Stable, size-controlled, narrowly dispersed populations of microbubbles have been obtained using fluorinated wall and/or internal gas components, allowing progress in the understanding of microbubble physics, and open new application perspectives. PMID:21816205

Krafft, Marie Pierre

2012-01-01

367

Effect of nitrogen addition on the properties of C:F thin films deposited by RF sputtering  

NASA Astrophysics Data System (ADS)

Fluorocarbon (C:F) and nitrogen-doped fluorocarbon (C:F:N) thin films are deposited by RF magnetron sputtering using a polytetrafluoroethylene (PTFE) target and Ar or Ar/N{2} sputtering gas. Properties of C:F:N films are compared to those of C:F films. They are studied using X-ray Photoelectron Spectroscopy (XPS), Infra-Red (IR) transmission spectroscopy, Thermo-Gravimetric Analysis (TGA), impedance spectroscopy, and current-voltage measurements. By adding nitrogen to the sputtering gas, XPS shows that nitrogen substitutes for fluorine leading to a decrease in the relative concentration of CF{x} species, to an increase in C-C bonds, and to the appearance of specific CFN bonds. There is also a new IR band at 1350 cm-1 whose origin is uncertain (CN bonds or disordered sp2 carbon). Thermal stability is not improved upon nitrogen addition (the C:F and C:F:N films both decompose above 200 °C). Dielectric properties (dielectric constant and loss) are only slightly affected by nitrogen doping. The DC transport properties are modified upon nitrogen addition (C:F:N films display a higher resistivity and a supra-linear behaviour at high fields indicative of field-enhanced tunnelling transport).

Gonon, P.

2005-10-01

368

Radio-frequency gas discharge (RFGD) fluorination of polymers: Protein and cell interactions at RFGD-fluorinated interfaces  

NASA Astrophysics Data System (ADS)

Proteins naturally adsorb at foreign surfaces. Adsorbed proteins on biomaterial surfaces are important to the biocompatibility of medical implants and devices, as well as to uses in biosensors, diagnostics, separations and industrial bioprocesses. There is ample evidence that the composition, organization, and conformations of the proteins adsorbed at a foreign interface are sensitive to the composition, topography, and molecular mobility of the substrate surface. The protein layer can also change in all the above aspects with time. Thus, it is a dynamic, "living" coating whose character is a direct reflection of the character of the substrate surface. Therefore, it is not surprising that many researchers have modified biomaterial surface compositions in order to influence protein absorption and subsequent conformational changes. The gas discharge process is one of the more useful methods for modification of biomaterial surfaces. Surfaces may be ablated (or etched) in a process which removes material and creates a cleaner, but chemically-modified surface. Gas discharge may also be used to deposit a polymer-like coating of a new composition on the surface, such as silicone and fluorocarbon coatings on hydrocarbon polymer surfaces. Certain of these fluorocarbon discharge-deposited polymers have been shown to enhance retention of adsorbed proteins, presumably by increased hydrophobic interactions with the modified substrate. Furthermore, platelet adhesion on such surfaces may be increasingly reduced as the adsorbed protein is increasingly bound to the fluorinated surface. These unusual results and their biologic implications are discussed in this paper.

Kiaei, David; Hoffman, Allan S.; Horbett, Thomas A.

1995-08-01

369

Measurement of plasma-surface interaction in CF_4/Ar RF-ICP by using CT-OES  

NASA Astrophysics Data System (ADS)

Highly selective SiO2 etch over Si is required to manufacture ULSI devices. Reactive ion etching using polymerizing fluorocarbon chemistries provides the process for selective dry etching of SiO2 over Si. A number of species including electrons, ions, and radicals are generated in the plasma processing by reactions in gas phase and on surface. A large amount of highly reactive fluorine atoms, fluorocarbon radicals, ions from the plasma interact with the substrate and produce etch products. These etch products, primarily SiF4 and SiF_2, diffuse back into the bulk plasma where they are dissociated and ionized by electrons and the resultant products are transported and redeposited onto the substrate and/or surface. That is, the plasma structure will be quite different whether the surface is exposed to etching or not. It will be essential to investigate the spatio temporal characteristics of plasma structure during etching process. In our recent study, we have mainly measured spatio temporal structure of excited SiF(A^2 °^+) and F(3^4D_7/2) in CF_4/Ar mixture driven by RF(13.56MHz)-ICP during Si etching, by using CT(Coumputerized Tomography)-OES(Optical Emission Spectroscopy) system. We discuss the plasma structure during Si etching as a function of LF(500 kHz) bias source.

Miyoshi, Yasufumi; Miyauchi, Masaru; Oguni, Atsushi; Makabe, Toshiaki

2004-09-01

370

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

NASA Technical Reports Server (NTRS)

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.

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

1984-01-01

371

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)

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.

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

1990-01-01

372

Impacts of CF+, CF2+, CF3+, and Ar Ion Beam Bombardment with Energies of 100 and 400 eV on Surface Modification of Photoresist  

NASA Astrophysics Data System (ADS)

Photoresists used in advanced ArF-excimer laser lithography are not tolerant enough for plasma etching processes. Degradation of photoresists during etching processes might cause not only low selectivity, but also line edge roughness (LER) on the sidewalls of etched patterns. For a highly accurate processing, it is necessary to understand the mechanisms of etching photoresists and to construct a new plasma chemistry that realizes a nano scale precise pattern definition. In this study, the modified layers formed on the surface of a photoresist by the bombardment of fluorocarbon ions of CF+, CF2+, and CF3+, and argon (Ar) ions were analyzed by X-ray photoelectron spectroscopy (XPS). The etching yield of the modified steady-state surface was almost dependent on the mass of incident ion species. The surface composition was modified with increasing dosage of each ion species, and reached a specific steady state that was dependent on the ion species. The bombardment of F-rich ion species such as CF2+ and CF3+ resulted in the formation of not only fluorocarbon layers, but also graphite like structures on the surface. On the basis of these results, the surface reaction for the ion-beam-induced modification was discussed.

Takeuchi, Takuya; Amasaki, Shinpei; Kondo, Hiroki; Ishikawa, Kenji; Toyoda, Hirotaka; Sekine, Makoto; Kang, Song-Yun; Sawada, Ikuo; Hori, Masaru

2011-08-01

373

The Curve of Binding Energy  

NASA Astrophysics Data System (ADS)

With the new low-energy ion beamline, experiments have been performed on (fluoro)carbon ion (C+, CF+, CF2+ and CF3+) scattering from the PFPE surface in the hyperthermal incident energy range 50-to 220-eV. These experiments are described in chapter 6 of this thesis. A comparative study is carried out on energy transfer to the surface and to internal energy of the scattered ions. Surprisingly, the experimental results reveal that more of the translational energy lost in the collision is transferred to internal energy in the case of CF3+ (19%) than in CF2+ (14%) and CF+ (13%) scattering. A simple model is introduced which predicts that the incident CF3+ ion has more orientations favorable for internal energy uptake than the CF+ and CF2+ ions. The surface effective mass increases linearly with the number of atoms the fluorocarbon contains, giving information on the number of target atoms involved in the scattering event. This chapter represents the first detailed study on energy transfer to liquid surfaces in atomic and polyatomic ion scattering.

Marakuma, Sinji; Drew, Nancy

2004-03-01

374

Detection of Chamber Conditioning by CF4 Plasmas in an Inductively Coupled GEC Cell  

NASA Astrophysics Data System (ADS)

During oxide etch processes, buildup of fluorocarbon residues on reactor sidewalls can cause run-to-run 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 useable 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 and CF4 plasmas. A slight rise in electron density is also observed by probe, ion flux and impedance measurements 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. The optical emission of several species 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.

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

2001-10-01

375

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

NASA Technical Reports Server (NTRS)

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.

Shiner, C. S.

1986-01-01

376

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

NASA Technical Reports Server (NTRS)

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.

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

1978-01-01

377

Design and chemical synthesis of iodine-containing molecules for application to solar-pumped I* lasers. Semiannual progress report, 1 January-30 June 1986  

SciTech Connect

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.

Shiner, C.S.

1986-01-01

378

Amorphous Silicon and Tungsten Etching Employing Environmentally Benign Plasma Process  

NASA Astrophysics Data System (ADS)

A novel dry etching process for amorphous silicon (a-Si) and tungsten (W) for chemical vapor deposition (CVD) chamber cleaning has been performed by electron cyclotron resonance (ECR) O2 plasma employing a solid-material evaporation system where fluorocarbon species are produced from fluorinated ethylene propylene (FEP) by CO2 laser evaporation for preventing global warming. This process enables us to realize etching of materials without using any perfluorocompound (PFC) feed gases which have a high global warming potential (GWP). Etching characteristics together with diagnostics of the F atom density, CFx (x=1--3) radical densities, electron density and temperature have been investigated as functions of pressure. As a result, it was found that etching rates of a-Si and W films were determined based on the F atom density, ion flux and ion bombardment energy. Furthermore, etching rates of a-Si and W films increased by heating the fluorocarbon species before introducing them into the plasma reactor. Thus, high rates of etching of a-Si and W films were successfully achieved by this novel etching process compared with conventional etching using ECR plasma with CF4/O2 feed gases.

Fujita, Kazushi; Kobayashi, Shigeto; Ito, Masafumi; Hori, Masaru; Goto, Toshio

2001-02-01

379

Atomic Oxygen Effects on Seal Leakage  

NASA Technical Reports Server (NTRS)

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 if 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.

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

1998-01-01

380

Atomic Oxygen Effects on Seal Leakage  

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

381

Designing novel hybrid materials by one-pot co-condensation: from hydrophobic mesoporous silica nanoparticles to superamphiphobic cotton textiles.  

PubMed

This work reports the synthesis and characterization of mesoporous silica nanoparticles (MSNs) functionalized with tridecafluorooctyltriethoxysilane (F13) and their in situ incorporation onto cotton textiles. The hybrid MSNs and the functional textiles were prepared by a one-pot co-condensation methodology between tetraethylorthosilicate (TEOS) and F13, with hexadecyltrimethylammonium chloride (CTAC) as the template and triethanolamine as the base. The influence of the F13 to TEOS molar ratio (1:10, 1:5 and 1:3) on the nanoparticle morphology, porosity, degree of functionalization, and hydro/oleophobic properties is discussed. The hybrid nanosilicas presented high colloidal stability and were spherical and monodispersed with average particle size of ?45 nm. They also showed high surface areas, large pore volumes, and a wormhole-type mesoporous structure. The increase in the organosilane proportion during the co-condensation process led to a more radially branched wormhole-like mesoporosity, a decrease in the surface area, pore volume, and amount of surface silanol groups, and an enrichment of the surface with fluorocarbon moieties. These changes imparted hydrophobic and oleophobic properties to the materials, especially to that containing the highest F13 loading. Cotton textiles were coated with the F13-MSNs through an efficient and less time-consuming route. The combination between surface roughness and mesoporosity imparted by the MSNs, and the low surface energy provided by the organosilane resulted in superhydrophobic functional textiles. Moreover, the textile with the highest loading of fluorocarbon groups was superamphiphobic. PMID:21615151

Pereira, C; Alves, C; Monteiro, A; Magén, C; Pereira, A M; Ibarra, A; Ibarra, M R; Tavares, P B; Araújo, J P; Blanco, G; Pintado, J M; Carvalho, A P; Pires, J; Pereira, M F R; Freire, C

2011-07-01

382

Optimization of the Properties of Carbon Nanotube-Based Structures by Electron and Ion Beam Irradiation  

NASA Astrophysics Data System (ADS)

There is considerable interest in building new nanostructures for electronic devices and incorporating nanostructured fibers and particles into composites. Here, classical molecular dynamics simulations are used to study the production of new carbon nanotube junctions or cross-links through electron irradiation, in addition to the chemical modification of carbon nanotube-based structures and composites through ion and polyatomic ion beam deposition. In particular, electron irradiation is used to produce junctions between carbon nanotubes. The specific reactions that lead to junction-formation and the mechanical and electronic properties of the resulting junctions will be discussed. Additionally, the chemical modification of multi-walled nanotubes, single-walled and multi-walled nanotube bundles, nanopeapods, and nanotube-polymer composites from polyatomic fluorocarbon ions, which are commonly present in low-energy fluorocarbon plasmas, and Ar will be presented. Multi-walled carbon nanotubes usually fail through the so-called ``sword-and-sheath'' mechanism and nanotube-polymer composites often fail through nanotube pullout. In both cases the failure mechanism is due to the weak van der Waals bonds between either the nanotube shells in the multi-walled tube or between the nanotubes and polymer matrix in the composite. The simulation results show that ion beam deposition produces cross-links between shells in multi-walled nanotubes and between otherwise unfunctionalized nanotubes and polymer backbone chains, which ultimately toughens the composites. The conditions that are predicted to be optimum for effective chemical modification of the system will be discussed.

Sinnott, Susan

2005-03-01

383

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

PubMed

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

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

2012-09-26

384

Polyelectrolyte multilayers with perfluorinated phthalocyanine selectively entrapped inside the perfluorinated nanocompartments.  

PubMed

A novel perfluorinated magnesium phthalocyanine (MgPcF64) was synthesized and employed to probe nanodomains in hydrophobically modified, amphiphilic cationic polyelectrolytes bearing alkyl and/or fluoroalkyl side chains. MgPcF64 was found to be solubilized exclusively in the aqueous solutions of the fluorocarbon modified polycations, occupying the perfluorinated nanocompartments provided, while analogous polyelectrolytes with alkyl side chains forming hydrocarbon nanocompartments could not host the MgPcF64 dye. Multilayer films were fabricated by means of the layer-by-layer (LbL) deposition method using sodium poly(styrene sulfonate) as a polyanion. Linear multilayer growth was confirmed by UV-Vis spectroscopy and spectroscopic ellipsometry. Atomic force microscopy studies indicated that the micellar conformation of the polycations is preserved in the multilayer films. Fluorescence spectroscopy measurements confirmed that MgPcF64 stays embedded inside the fluorocarbon domains after the deposition process. This facile way of selectively incorporating water-insoluble, photoactive molecules into the structure of polyelectrolyte multilayers may be utilized for nanoengineering of ultrathin film-based optoelectronic devices. PMID:24653994

Kope?, Maciej; Lapok, Lukasz; Laschewsky, Andre; Zapotoczny, Szczepan; Nowakowska, Maria

2014-03-14

385

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

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.

Hua Xuefeng; Stolz, Christian; Oehrlein, G.S.; Lazzeri, P.; Coghe, N.; Anderle, M.; Inoki, C.K.; Kuan, T.S.; Jiang, P. [Department of Physics and Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States); Department of Materials Science and Engineering and Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States); ITC-irst, Center for Scientific and Technological Research, 38050 Povo, Trento (Italy); Department of Physics, University at Albany, SUNY, Albany, New York 12222 (United States); Texas Instruments, Inc., Dallas, Texas 75243 (United States)

2005-01-01

386

Synthesis of new high performance lubricants and solid lubricants  

SciTech Connect

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.

Lagow, Richard J.

1993-04-08

387

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

NASA Astrophysics Data System (ADS)

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 ?-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.

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

2014-05-01

388

Fluorine bonding enhances the energetics of protein-lipid binding in the gas phase.  

PubMed

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 ?-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. PMID:24658801

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

2014-05-01

389

Cell separations and the demixing of aqueous two phase polymer solutions in microgravity  

NASA Technical Reports Server (NTRS)

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.

Brooks, Donald E.; Bamberger, Stephan; Harris, J. M.; Van Alstine, James M.

1991-01-01

390

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

NASA Astrophysics Data System (ADS)

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.

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

2008-07-01

391

Wide Angle, Single Screen, Gridded Square-Loop Frequency Selective Surface for Diplexing Two Closely Separated Frequency Bands  

NASA Technical Reports Server (NTRS)

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.

Wu, Te-Kao (Inventor)

1996-01-01

392

Network flow model analysis of the impact of chlorofluorocarbon phaseout on acid-grade fluorspar. Information circular/1994  

SciTech Connect

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.

Slatnick, J.A.; Fulton, R.B.

1994-12-31

393

Blood substitutes made on the basis of perfluorocarbons inhibit intracellular energy generation.  

PubMed

Although perfluorocarbons (PFC) are chemically inert, toxic reactions are observed on using them as fluorocarbon emulsions in blood substitutes. Six to twelve hours after exchanging about half of the circulating blood of conscious rats pathobiochemical reactions occur despite a high interarterial oxygen pressure. They indicate the disturbance of intracellular energy generation, which is characterized by a decrease in ATP, increase in ADP, inorganic phosphate and potassium, increase in NADH and lactate. Impurities of perfluorocarbons and effects of the surfactant were excluded to be causes of this disturbance. The following hypotheses were proposed: Storing of perfluorocarbons in the mitochondrial membrane decreases the ATP-forming proton gradient on the membrane and the electron transport in cytochromes is disturbed, respectively. PMID:1391420

Reichelt, H; Draffehn, J; Rüdiger, S; Gross, U

1992-01-01

394

Manufacture and quality control of interconnecting wire hardnesses, Volume 1  

NASA Technical Reports Server (NTRS)

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.

1972-01-01

395

Development of inspection techniques for quantitatively measuring surface contamination on SRM hardware  

NASA Technical Reports Server (NTRS)

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.

Law, R. D.

1989-01-01

396

Plasma and ion fluorination for chemical hardening of synthetic rubbers. Final report, 30 September 1988-30 September 1989  

SciTech Connect

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.

Legg, K.O.

1989-10-01

397

The equation of state of supercritical HF, HCl, and reactive supercritical mixtures containing the elements H, C, F, and Cl  

NASA Astrophysics Data System (ADS)

We develop a model of chemical equilibrium mixtures containing the elements H, C, F, and Cl. The model is based on a recently developed equation of state for the exponential-6 fluid, combined with a simple equation of state for condensed carbon. We show that the shock response of a wide variety of molecular and polymeric fluorocarbons and chlorocarbons can be modeled as a chemical equilibrium mixture of a small number of dissociation product molecules. In particular, we predict that shocked polyvinylidine fluoride (PVF2) decomposes into a fluid phase composed mostly of HF, and a phase containing condensed carbon. HF is known to strongly associate in the supercritical fluid phase. We predict that such an association also occurs under shock conditions.

Fried, Laurence E.; Michael Howard, W.

1999-06-01

398

The equation of state of dense reactive supercritical mixtures containing the elements H, C, F, and Cl  

NASA Astrophysics Data System (ADS)

We develop a model of chemical equilibrium mixtures containing the elements H,C, F, and Cl. The model is based on a recently developed equation of state for the exponential-6 fluid, combined with a simple model of condensed carbon. Our model shows that the shock response of a wide variety of molecular and polymeric fluorocarbons and chlorocarbons can be modeled as a chemical equilibrium mixture of a small number of dissociation product molecules. In particular, we predict that shocked polyvinylidine fluoride (PVF2) decomposes into a fluid phase composed mostly of HF, and a phase containing condensed carbon. HF is known to strongly associate in the supercritical fluid phase. Our model predicts that such an association also occurs under shock conditions.

Fried, Laurence E.; Howard, W. Michael

1999-06-01

399

Apparatus and method for atmospheric pressure reactive atom plasma processing for shaping of damage free surfaces  

DOEpatents

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.

Carr; Jeffrey W. (Livermore, CA)

2009-03-31

400

Measurements of desorbed products by plasma beam irradiation on SiO2  

NASA Astrophysics Data System (ADS)

A plasma beam irradiation apparatus with a controllable plasma source was constructed to investigate the plasma-surface interactions for reactive etching processes. The apparatus can control the plasma parameters, such as ion energy, radical/ion composition, and the ratio of neutral to ion flux. The desorbed products of SiFx (x=1-3) were observed separately from COFx (x=1-3) by using a 13CF4-Ar gas mixture plasma beam. The major desorbed product was not SiF4. Unsaturated fluorinated silicons [SiFx (x=1-3)] were major desorbed products under ion-rich fluorocarbon plasma etching condition. It was found that the composition of silicon containing desorbed products does not depend on the incident ion energy in the ion energy range of 300-700 eV.

Kurihara, Kazuaki; Yamaoka, Yoshikazu; Karahashi, Kazuhiro; Sekine, Makoto

2004-11-01

401

Inspection of small multi-layered plastic tubing during extrusion, using low-energy X-ray beams  

NASA Astrophysics Data System (ADS)

The automotive industry uses nylon tubing with a thin ETFE (ethylene-tetrafluroethylene) inner layer to carry fuel from the tank to the engine. This fluorocarbon inner barrier layer is important to reduce the migration of hydrocarbons into the environment. Pilot Industries has developed a series of real-time inspection stations for dimensional measurements and flaw detection during the extrusion of this tubing. These stations are named LERA TM (low-energy radioscopic analysis), use a low energy X-ray source, a special high-resolution image converter and intensifier (ICI) stage, image capture hardware, a personal computer, and software that was specially designed to meet this task. Each LERA TM station operates up to 20 h a day, 6 days a week and nearly every week of the year. The tubing walls are 1-2 mm thick and the outer layer is nylon and the inner 0.2 mm thick layer is ethylene-tetrafluroethylene.

Armentrout, C.; Basinger, T.; Beyer, J.; Colesa, B.; Olsztyn, P.; Smith, K.; Strandberg, C.; Sullivan, D.; Thomson, J.

1999-02-01

402

Thermal conductivity of gaseous HFC-134a, HFC-143a, HCFC-141b, and HCFC-142b  

NASA Astrophysics Data System (ADS)

The thermal conductivity of new environmentally acceptable fluorocarbons HFC-134a (CH2FCF3), HFC-143a (CH3CF3), HCFC-141b (CH3CCl2F), and HCFC-142b (CH3CCl2F) in the gaseous phase has been measured in the temperature range 293 353 K at pressures up to 4 MPa. The thermal conductivity has been measured with a coaxial-cylinder cell on a relative basis. The apparatus was calibrated with He, Ne, Ar, Kr, N2, CH4, and SF6 as reference fluids. The uncertainty of the experimental data obtained is estimated to be within 2% except for the uncertainty associated with the reference thermal-conductivity values. The excess thermal conductivity has been correlated satisfactorily as a function of density.

Tanaka, Y.; Nakata, M.; Makita, T.

1991-11-01

403

SiO2 Hole Etching Using Perfluorocarbon Alternative Gas with Small Global Greenhouse Effect  

NASA Astrophysics Data System (ADS)

The etching of contact holes of 0.1 ?m size in SiO2 is achieved using, for the first time, cyclic (c-)C5F8 with a small greenhouse effect in the pulse-modulated inductively coupled plasma. The shape of the cross section of the contact hole is as good as that etched using conventional c-C4F8. It is confirmed that Kr mixing instead of Ar in the plasma does not change the etching characteristics, although lowering of the electron temperature is expected which reduces the plasma-induced damage. Pulse modulation of the plasma is found to improve the etching selectivity of SiO2 with respect to Si. Langmuir probe measurement of the plasma suggests that the improvement of the etching selectivity is due to the deposition of fluorocarbon film triggered by lowering of the electron temperature when the off time of the radio frequency (rf) power is extended.

Ooka, Masahiro; Yokoyama, Shin

2004-06-01

404

Investigation of structure-surface properties relationship of semi-fluorinated polymerizable cationic surfactants.  

PubMed

Novel hybrid hydrocarbon/fluorocarbon ammonium type surfactant monomers (surfmers) of the general formula RF (CH2)l N(CH3)2(CH2)mOCOCH=CH2 with (RF=C4F9, C6F13, C8F17, l=4, 6, 11, and m=2-11) were synthesized and characterized. They exhibit very low surface tension as well as low critical micellar concentrations down to 1.39×10(-5)mol/L. Special attention was focused on theeffect of the polymerizable moiety, the length of the hydrocarbon spacers, and the fluorinated chains on surface activities of the reactive surfactants as compared to hydrocarbon surfmer analogs. Results indicate that the acrylic function has a pronounced effect on increasing the hydrophobic micelle character. This was confirmed by surface tensions and average surfaces occupied by these molecules at the water-gas interface. The micellar sizes were investigated by dynamic light scattering. PMID:23932087

Benbayer, Chahinez; Saidi-Besbes, Salima; Taffin de Givenchy, Elisabeth; Amigoni, Sonia; Guittard, Frédéric; Derdour, Aicha

2013-10-15

405

The 1977 intertropical convergence zone experiment  

NASA Technical Reports Server (NTRS)

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.

Poppoff, I. G. (editor); Page, W. A. (editor); Margozzi, A. P. (editor)

1979-01-01

406

Tangential flow filtration and preliminary phylogenetic analysis of marine picoplankton.  

PubMed Central

A procedure was developed for harvesting gram quantities of microbial biomass from oligotrophic waters, when mixed populations are present in low abundance. Picoplankton from Atlantic Ocean (Hydrostation S, Sargasso Sea) and Pacific Ocean (Aloha Station) sites were collected in a three-stage process: (i) collection of seawater through an intake covered with 10-microns-pore Nytex; (ii) concentration by a tangential flow filtration device equipped with 10 ft2 (0.929 m2) of 0.1-micron-pore fluorocarbon membrane; (iii) collection of cells from concentrate by centrifugation. The overall efficiency of picoplankton recovery was at least 37%. The cellular morphotypes recovered matched those of the original population. DNA was prepared from frozen cell pellets by enzymatic digestion, solvent extraction, and isopycnic centrifugation. As indicated by the binding of kingdom-specific hybridization probes to the purified DNA, the Sargasso Sea picoplankton in this collection were largely eubacteria. Images

Giovannoni, S J; DeLong, E F; Schmidt, T M; Pace, N R

1990-01-01

407

The Effect of Oil Contamination on Evaporator Heat Transfer Characteristics of CO2 Refrigeration Cycle  

NASA Astrophysics Data System (ADS)

Because of the destructions of ozone layers and global warming, it is urgently necessary to abolish fluorocarbon refrigerants of HFCs and substitute them with natural refrigerants. Among several choices of natural refrigerants, CO2, which has an excellent thermal property, has the advantage for practical application. However, heat transfer coefficient and pressure drop of evaporator have not studied enough. No available correlation has been established. The refrigerant of CO2 is extremely sensitive to oil. Therefore, the research on the refrigerant under the circumstances that it is mixed with oil is very limited. It is the purpose of this research to examine the oil mixing effects on thermal and fluid dynamic behaviors and establish correlation.

Katsuta, Masafumi; Kinpara, Hiromitsu; Yagi, Shunta; Mukaiyama, Hiroshi

408

Development of a special purpose spacecraft interior coating, phase 1  

NASA Technical Reports Server (NTRS)

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.

Bartoszek, E. J.; Nannelli, P.

1975-01-01

409

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

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.

Monson, P.R. Jr.

1982-01-01

410

Effect of Side Chains on Charge Transfer in Quaterthiophene-Naphthalene Diimide Based Donor-Bridge-Acceptor Dyads  

SciTech Connect

We have probed the effect of side chains on the charge transfer dynamics in dyads containing quaterthiophene (QT) donor and naphthalene diimide (NDI) acceptor. The donor and the acceptor are covalently linked using a flexible linker. Four dyads (1–4) were synthesized with the quaterthiophene bearing hexyl side chain and the naphthalene diimide bearing hydrocarbon, fluorocarbon, branched or polar side chains. The UV-Vis spectra for these dyads showed the existence of a donor-acceptor complex. The time-resolved fluorescence (TRF) decay studies show a rapid quenching of fluorescence in all the dyads upon excitation of the donor. We found that the side chains on the NDI did not alter the quenching rates in solution.

Bheemaraju, A.; Pourmand, M.; Yang, B.; Surampudi, S.; Benanti, T.; Achermann, M.; Barnes, M. D.; Venkataraman, D.

2011-01-01

411

Fine Contact Hole Etching in Magneto-Microwave Plasma  

NASA Astrophysics Data System (ADS)

Characteristics of fine contact hole etching have been investigated in hydro-fluorocarbon magneto-microwave plasma focusing on the z component of the gradient of magnetic field at 0.0875 T ( dB/ dz) and peak-to-peak voltage of RF bias (V pp) as parameters. Decrease of dB/ dz drastically decreases the etch rate of boro-phospho silicate glass (BPSG), critical dimension loss (defined as diameter of the top of contact hole minus diameter of the bottom of resist) and selectivity over heavily doped n-type polycrystalline silicon ( n+ poly Si) and resist in fine contact holes. The changes of etching characteristics are correlated with neither F/C ratio nor C1s spectrum of deposited film, but with deposition rate in the region of high V pp, which presumably reflects the change of incident CF m+ ion species with dB/ dz.

Miyakawa, Yasuhiro; Hashimoto, Jun; Ikegami, Naokatsu; Matsui, Takayuki; Kanamori, Jun

1994-04-01

412

Ion energy distribution and optical measurements in high-density, inductively coupled C4F6 discharges  

NASA Astrophysics Data System (ADS)

Hexafluoro-1,3 butadiene (C4F6) is a potential etching gas with a very low global warming potential for the manufacturing of semiconductors, unlike commonly used fluorocarbon gases such as CF4 and c-C4F8. We report ion energy distributions, relative ion intensities and absolute total ion current densities measured at the edge of an inductively coupled gaseous electronics conference radio-frequency reference cell for discharges generated in pure C4F6 and C4F6:Ar mixtures. In addition, the ratio of radical densities relative to CF measured using submillimeter absorption spectroscopy and optical emission spectroscopy measurements are presented. These measurements of the C4F6 plasmas were made for several different gas pressures (0.67, 1.33, and 2.66 Pa) and gas mixture ratios (25%, 50%, 75%, and 100% C4F6 volume fractions).

Benck, Eric C.; Goyette, Amanda; Wang, Yicheng

2003-08-01

413

Scientific assessment of stratospheric ozone: 1989. Volume 2: Appendix: AFEAS report  

SciTech Connect

The outcome is presented of the Alternative Fluorocarbon Environmental Acceptability Study (AFEAS). AFEAS evaluated the potential effects on the environment of alternative compounds targeted to replace fully halogenated chlorofluorocarbons (CFCs). Emphasis was placed on the following topics: (1) the potential of the compounds to affect stratospheric ozone; (2) their potential to affect tropospheric ozone; (3) their potential to contribute to model calculated global warming; (4) the atmospheric degradation mechanisms of the compounds, in order to identify their products and hence; (5) the potential environmental effects of the decomposition products. The alternative compounds were hydrofluorocarbons (HFCs) with one or two carbon atoms and one or more each of fluorine and hydrogen and hydrochlorofluoro carbons (HCFCs).

Not Available

1989-01-01

414

Role of CFC's, substitutes, and other halogenated chemicals in climate change  

SciTech Connect

Because of their ozone depleting potential the most important chlorofluorocarbons and halons have been subjected to international control by the Montreal Protocol. Generally these substances play also a significant role in the greenhouse effect. For the implementation of the Montreal agreement measures have to be taken, including conservation, recycling and the application of alternative products. Presently a complete phase out of the regulated CFCs is being negotiated. The feasibility of such a phase out is suggested to be dependent on the development of alternative halocarbons, notably the partly halogenated chlorofluorocarbons (HCFCs) and fluorocarbons (HFCs). Also other existing ozone depleting substances have been brought into the discussion: carbon tetrachloride and methylchloroform. The report evaluates the consequences of different policies with respect to these nonregulated products for climate change.

den Elzen, M.G.J.; Rotmans, J.; Swart, R.J.

1990-07-01

415

Corrosion of current-collector materials in Li-ion cells  

SciTech Connect

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).

Braithwaite, J.; Nagasubramanian, G.; Gonzales, A.; Lucero, S.; Cieslak, W.

1996-12-01

416

Effects of acid-washing filter treatment on quantification of aerosol organic compounds  

NASA Astrophysics Data System (ADS)

The tests of standard mixtures and four sets of atmospheric particulate samples showed that an acid-wash (AW) pretreatment of fluorocarbon-coated glass fiber filters prior to aerosol sampling enhanced the quantifiable organic compounds for more than 29% (or 66 ng m -3); in particular, 47-273 ng m -3 (21-366%) more water-soluble organic compounds (WSOCs) were measured. When the acid-pretreated filters were employed, up to nine more organic species were measured in the individual daily samples. Because the acid pretreatment reduced the metal contaminants in the glass fiber filters, using the AW filters for aerosol sampling allows higher extraction recoveries of organic compounds. Since the fingerprinting compounds were more accurately determined when the aerosol samples were collected on the AW filters, better assessment of emission sources and toxicity of air pollutants can be obtained.

Yang, Liming; Lim, Jaehyun; Yu, Liya E.

417

Metal Surface Decontamination by the PFC Solution  

SciTech Connect

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)

Hui-Jun Won; Gye-Nam Kim; Wang-Kyu Choi; Chong-Hun Jung; Won-Zin Oh [Korea Atomic Energy Research Institute - KAERI, P.O.Box 105, Yuseong, Daejeon, Korea, 305-353 (Korea, Republic of)

2006-07-01

418

Mass analysis of neutral particles and ions released during electrical breakdowns on spacecraft surfaces  

NASA Technical Reports Server (NTRS)

A specialized spectrometer was designed and developed to measure the mass and velocity distributions of neutral particles (molecules and molecular clusters) released from metal-backed Teflon and Kapton films. Promising results were obtained with an insulation breakdown initiation system based on a moveable contact touching the insulated surfaces. A variable energy, high voltage pulse is applied to the contact. The resulting surface damage sites can be made similar in size and shape to those produced by a high voltage electron beam system operating at similar discharge energies. The point discharge apparatus was used for final development of several high speed recording systems and for measurements of the composition of the materials given off by the discharge. Results with this apparatus show evolution of large amounts of fluorocarbon fragments from discharge through Teflon FEP, while discharges through Kapton produce mainly very light hydrocarbon fragments at masses below about 80 a.m.u.

Kendall, B. R. F.

1983-01-01

419

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

NASA Technical Reports Server (NTRS)

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.

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

1991-01-01

420

Spacecraft dielectric material properties and spacecraft charging  

NASA Technical Reports Server (NTRS)

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.

Frederickson, A. R.; Wall, J. A.; Cotts, D. B.; Bouquet, F. L.

1986-01-01

421

Dynamic aspects of detonations; International Colloquium on Dynamics of Explosions and Reactive Systems, 13th, Nagoya, Japan, July 28-Aug. 2, 1991, Technical Papers  

NASA Astrophysics Data System (ADS)

Various papers on the dynamic aspects of detonations are presented. Individual subjects addressed include: high-resolution numerical simulations for 2D unstable detonations, simulation of cellular structure in a detonation wave, Mach reflection of detonation waves, mechanism of unstable detonation front origin, numerical modeling of galloping detonation, experimental study of the fine structure in spin detonation, influence of fluorocarbon on H2O2Ar detonation, digial signal processing analysis of soot foils, cylindrical detonations in methane-oxygen-nitrogen mixtures, structure of reaction waves behind oblique shocks, ignition in a complex Mach structure, simulations for detonation initiation behind reflected shock waves. Also discussed are: limiting tube diameter of gaseous detonation, mechanisms of detonation propagation in a porous medium propagation and extinction of detonation waves in tube bundles, structure and velocity deficit of gaseous detonation in rough tubes, possible method for quenching of a gaseous detonation, effect of hollow heterogeneities on nitromethane detonation.

Kuhl, A. L.; Leyer, J.-C.; Borisov, A. A.; Sirignano, W. A.

422

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)

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.

Nimitz, Jonathan S.; Tapscott, Robert E.; Skaggs, Stephanie R.; Beeson, Harold D.

1991-02-01

423

Anti-stiction coating of PDMS moulds for rapid microchannel fabrication by double replica moulding  

NASA Astrophysics Data System (ADS)

In this paper, we report a simple and precise method to rapidly replicate master structures for fast microchannel fabrication by double replica moulding of polydimethylsiloxane (PDMS). A PDMS mould was surface-treated by vapour phase deposition of 1H,1H,2H,2H-perfluorodecyltrichlorosilane (FDTS), which resulted in an anti-stiction layer for the improved release after PDMS casting. The deposition of FDTS on an O2 plasma-activated surface of PDMS produced a reproducible and well-performing anti-stiction monolayer of fluorocarbon, and we used the FDTS-coated moulds as micro-masters for rapid replication of micro-structures, avoiding the necessity to have to use other, more costly and fragile master materials. Our protocol has been shown to reliably fabricate PDMS-based microfluidic devices in a low-cost and efficient manner. The replicas were further employed as micro-contract stamps to fabricate polymer-based waveguides.

Zhuang, Guisheng; Kutter, Jörg P.

2011-10-01

424

Anion Conducting Polymeric Materials For Use in Electrolytic Salt Splitters  

NASA Astrophysics Data System (ADS)

Anion Conducting Polymeric Materials for use in Electrolytic Salt Splitters Devon Renock and David S. Newman Department of Chemistry Bowling Green State University Bowling Green, OH 43403 An anion conducting form of Flemion was produced by attaching a benzo-crown ether to the Flemion backbone and then complexing the crown ether containing material with an alkali metal ion. The alkali metal ion became trapped in the crown forming a positively charged pendent group hanging from the Teflon-like fluorocarbon chain. This positively charged moiety allows negatively charged ions to pass through readily, but prevents positively charged ions prom passing through the material. Materials with Dibenzo-18-cr-6 complexed with Potassium ion, Benzo-18-cr-6 complexed with potassium ion, and benzo-15-cr-5 complexed with sodium ion were all used successfully.

Newman, David; Renock, Devon

1998-10-01

425

Syntheses and reactions of metal organics. XXL Syntheses of (1 H,1 H,2 H,2 H-polyfluoroalkyl)triisocyanate silanes and surface modification of glass  

Microsoft Academic Search

Four silane coupling agents having a fluorocarbon chain and three isocyanate groups as reactive centers, i.e. CF3(CF2)3CH2CH2Si(NCO)3 (1), CF3(CF2)5CH2CH2Si(NCO)3 (2), CF3(CF2)7CH2CH2Si(NCO)3 (3) and CF3(CF2)9CH2CH2Si(NCO)3 (4), were prepared by the hydrosilylation reaction of trichlorosilane with the corresponding 1H,1H,2H-polyfluoro-1-alkene [CF3(CF2)nCH=CH2, n = 3, 5, 7 and 9 in the presence of hydrogen hexachloroplatinate(IV), followed by reaction with silver cyanate. Their application to

Norio Yoshino; Yukishige Kondo; Takashi Yamauchi

1996-01-01

426

Versatile Coating  

NASA Technical Reports Server (NTRS)

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.

1990-01-01

427

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

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.

Feldmann, M.L.; Leahy, H.F.; Vinegar, A.

1997-10-01

428

Avoiding Steric' Congestion in Dendrimer Growth through Proportionate Branching: A Twist on da Vinci's Rule of Tree Branching  

PubMed Central

Making defect-free macromolecules is a challenging issue in 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 9,082 Da. Monodispersity is confirmed by nuclear magnetic resonance spectroscopy, mass spectrometry and small-angle X-ray scattering. Growing different parts proportionately, as nature does, could be a general strategy to achieve defect-free synthesis of macromolecules.

Yue, Xuyi; Taraban, Marc B; Hyland, Laura L.

2013-01-01

429

Aggregation of new bipolar glucosyled and cationic fluoroamphiphiles in aqueous media.  

PubMed

A new series of N-[3-(trimethylamino)propyl]-perfluoro-N-glucosyl amide-Iodides, differing by the length of the fluorocarbon tail (7, 9, and 11), have been synthesized in three steps involving unprotected glucose, N,N-dimethyl-1,3-propane diamine, the appropriate methyl-perfluoroalcanoate, and methyl iodide. Their aggregation and surface properties were studied in aqueous solution using conductivity, surface tension, and dynamic light scattering measurements. The critical micelle concentrations (CMC), the micellar aggregation numbers, the geometric packing parameters, the area/surfactant molecule at the interface, the surface excess concentration, the micellar ionization degree ?, and the free energies of micellization have been investigated. DLS results show various morphologies of aggregates such as micelles and vesicles according to the increase in the hydrophobic chain length. PMID:23058977

Ngo, Thi Huong Viet; Damas, Christine; Naejus, Régine; Coudert, Robert

2013-01-01

430

Chlorofluoromethanes in the stratosphere and some possible consequences for ozone  

NASA Technical Reports Server (NTRS)

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.

Turco, R. P.; Whitten, R. C.

1975-01-01

431

Plasma treatment of polymers for surface and adhesion improvement  

NASA Astrophysics Data System (ADS)

Different plasma treatments in a rf discharge of Ar, He, or N 2 are used to etch, cross-link, and activate polymers like PC, PP, EPDM, PE, PS, PET and PMMA. Due to the numerous ways a plasma interacts with the polymer surface, the gas type and the plasma conditions must be adjusted on the polymer type to minimize degradation and aging effects. Wetting and friction properties of polymers can be improved by a simple plasma treatment, demonstrated on PC and EPDM, respectively. However, the deposition of ultra-thin layers by plasma enables the adjustment of wetting properties, using siloxane-based or fluorocarbon films, and further reduction of the friction coefficient, applying siloxane or a-C:H coatings. Nevertheless, the adhesion of plasma-deposited coatings should be regarded, which can be enhanced by depositing a graded layer.

Hegemann, Dirk; Brunner, Herwig; Oehr, Christian

2003-08-01

432

Method of cooling zinc halogen batteries  

SciTech Connect

This disclosure relates to a method of cooling zinc halogen batteries which involves the use of a liquid-overfeed cooling system utilizing a fluorocarbon refrigerant or the like. This new method is adaptable for use in either cooling the battery store water during charge so that a solid halogen hydrate will form, or for use in cooling the battery electrolyte, or both. This direct cooling, liquid-overfeed system is especially suited for use with a series of batteries as is proposed for use in utility load leveling systems and provides several advantages over other conventional cooling alternatives including an improved coefficient of performance, better heat transfer and temperature control, and reduced capital cost.

Kodali, S.

1981-12-15

433

Laboratory Studies of Chemical and Photochemical Processes Relevant to Stratospheric Ozone  

NASA Technical Reports Server (NTRS)

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.

Zahniser, Mark S.; Nelson, David D.; Worsnop, Douglas R.; Kolb, Charles E.

1996-01-01

434

Study of toxicological evaluation of fire suppressants and extinguishers  

NASA Technical Reports Server (NTRS)

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.

1975-01-01

435

ICP Reactor Modeling: CF4 Discharge  

NASA Technical Reports Server (NTRS)

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.

Bose, Deepak; Govindan, T. R.; Meyyappan, M.

1999-01-01

436

Plasma Reactor Modeling and Validation Experiments  

NASA Technical Reports Server (NTRS)

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.

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

437

Replication of continuous-profiled micro-optical elements for silicon integration.  

PubMed

A novel scheme for the integration of diffractive optical elements onto silicon is presented. The processing is made in reverse order, meaning that the process of structuring the optical elements on the wafer precedes the silicon microstructuring. The first processing step on the wafer is the hot embossing of the optical microstructures into an amorphous fluorocarbon polymer spin coated on the wafer. The cured polymer forms a highly stable material with excellent optical properties. The remaining silicon processing is thus performed with the diffractive optical elements already in place. Two different diffractive structures were used in the development of the method-a (Fresnel) lens with a rather low f-number and a diffractive element producing a fan-out of a large number of paraxial beams. PMID:16422323

Hedsten, Karin; Magnusson, Anders; Melin, Jonas; Enoksson, Peter; Bengtsson, Jörgen; Nikolajeff, Fredrik; Karlén, David; Rödjegård, Henrik; Andersson, Gert

2006-01-01

438

Development of a high-efficiency, gas-fired, heat pipe, warm-air heating system  

NASA Astrophysics Data System (ADS)

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.

Feldman, S.; Becker, F.

1985-01-01

439

Thermodynamic and transport properties of some alternative ozone-safe refrigerants for industrial refrigeration equipment: Study in Belarus and Ukraine  

SciTech Connect

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, R125, and R32, and FC R218. The following properties are being investigated: (1) 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.

Grebenkov, A.J.; Klepatsky, P.M.; Beljajeva, O.V. [Inst. of Power Engineering Problems, Minsk (Belgium)] [and others

1996-05-01

440

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

NASA Astrophysics Data System (ADS)

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).

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

2000-10-01

441

Oil fill procesure for seismic marine streamer  

SciTech Connect

This patent describes a method for improving signal quality in urethane foam mounts utilized on hydrophones in conjunction with a seismic streamer. It comprises: purging a urethane foam mount with a fluid miscible with air and hydrocarbonaceous liquid having a selected density which liquid is used to dampen noise in a hydrophone where the fluid is a member selected from the group consisting of carbon dioxide, fluorocarbons, C{sub 1}{minus}C{sub 4} hydrocarbons, and mixtures thereof which member alone substantially displaces air from the streamer; and thereafter filling the seismic streamer with the hydrocarbonaceous liquid which mixes with the fluid and substantially retains the density of the liquid thereby maintaining neutral buoyancy of the streamer, substantially isolating the hydrophones from noise, and improving signal quality.

Buckles, J.J.

1990-08-21

442

Effects of tacky mat contamination on bond degradation for Chemlok/liner and NBR/liner bonds  

NASA Technical Reports Server (NTRS)

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.

Padilla, A. M.

1989-01-01

443

Pulsed Plasma Thruster Plume Study: Symmetry and Impact on Spacecraft Surfaces  

NASA Technical Reports Server (NTRS)

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.

Arrington, Lynn A.; Marrese, Colleen M.; Blandino, John J.

2000-01-01

444

Nanoscale coatings for control of interfacial bonds and nanotube growth  

NASA Astrophysics Data System (ADS)

This paper describes the usefulness of nanoscale coatings in improving some engineering materials having porous and uneven surfaces (microcellular foam, nanofibers, nanotubes, etc.). It is shown that 3-5 nm coatings deposited in microwave plasma can influence crucial properties for a wide variety of applications. Two coatings resulting in opposite chemistries have been studied, an oxide layer that increases surface reactivity , and a similar fluorocarbon layer that makes it inert. In-depth atomic level microscopic and spectroscopic investigations of nucleation and growth of these layers on various substrates have been reported earlier. The effectiveness of such coatings in modifying bond strength, wettability and catalytic activity of various porous and uneven carbon surfaces have been shown here. The following influences of nanoscale functional coatings have been elaborated upon: (a) modification of carbon-polymer interfaces (b) controlled metallization of carbon (c) influence of nano-coatings on catalytic activity, for formation of carbon nanotubes on larger structures.

Pulikollu, Rajasekhar V.; Mukhopadhyay, Sharmila M.

2007-06-01

445

Volatile organic components in the Skylab 4 spacecraft atmosphere  

NASA Technical Reports Server (NTRS)

The volatile organic components in the spacecraft cabin atmosphere of Skylab 4 were trapped on a solid adsorbent at various times during the mission. In post-flight analyses, more than 300 compounds in concentrations from less than 1 ppb up to 8000 ppb could be detected by high-resolution gas chromatography. In the samples of the 11th, 47th, and 77th day of the mission, approximately 100 components in the molecular weight range from 58 to 592 were identified by mass spectrometry. Besides components known from other environments, such as alkanes, alkenes, and alkylated aromatic hydrocarbons, components typical of the human metabolism, such as ketones and alcohols, were found. Other typical components in the spacecraft atmosphere included fluorocarbons and various silicone compounds, mostly normal and cyclic methylsiloxanes.

Liebich, H. M.; Bertsch, W.; Zlatkis, A.; Schneider, H. J.

1975-01-01

446

Coolant controversy heats up  

SciTech Connect

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.

Shanley, A.

1997-11-01

447

A prospective overview of the potential of fluorofullerenes as host materials for intercalation chemistry.  

PubMed

A theoretical survey of the ability of fluorofullerene crystals to act as host lattices for intercalation chemistry is proposed on a thermochemical basis and from the assumption that complete charge transfer between the fluorocarbon network and an electropositive intercalant species should occur upon insertion. A nearly exhaustive examination is performed throughout the fluoro[60]fullerene family, describing the influence of the intercalated element considered, stoichiometry, structural type, and fluorine content on the potential stability of an intercalated phase. Decomposition of the latter into a metal fluoride is then discussed. When extended to a general scheme, emphasizing the role played by the number of carbon atoms in the initial cluster, the present model shows that stable fluorofulleride salts may be expected to form in some cases. A final insight into the solid state properties of this class of materials, combined with a widespread range of potential applications, is provided. PMID:16852534

Claves, Daniel

2005-06-30

448

Decomposed Fragment Identification in C_8F_18 RF Plasma for a-C:F Film Production  

NASA Astrophysics Data System (ADS)

Amorphous fluorocarbon polymer (a-C:F) film shows excellent insulation properties such as low dielectric constant (<2.5), high dielectric strength (>2 MV/cm), low surface energy, and chemical inertness. Therefore, we have studied this film for a purpose of an additional insulator to enhance the breakdown voltage in an alternative to a SF6 gas insulation system. The films are prepared using a C_8F_18 vapor RF plasma. When per-fluorocarbon, such as C_8F_18 as source gases, then the deposition rate becomes roughly two orders of magnitude higher than that obtained from conventional low molecular-weight source monomers (CF_4, C_2F_6, C_3F_6, and C_4F_8) [1]. The breakdown voltage (V_s) of N_2, Ar and He gases between the a-C:F film coated Al sphere-sphere electrodes for a gas pressure (p) times gap length (d), pd=0.1-100 Torr¥cm, was studied as well. Then, Vs between the a-C:F film coated electrodes was a several times higher than that between the Al electrodes in the present pd range[2]. In this work, the decomposed species of C_8F_18 in the plasma were identified using emission spectra from the plasma and Quadra-pole mass spectrograph, and the reason why the high deposition rate was obtained was discussed. The physical and chemical properties of a-C:F film was analyzed. [1] C.P.Lungu, et.al., Jpn. J. Appl. Phys. 38 (12B) L1544 - L1546 (1999) [2] C.Biloiu, et.al., Jpn. J. Appl. Phys. 42 (2B) L 201- L203 (2003) Work supported by Grant-in-Aid for Scientific Research (B), JSPS.

Sakai, Yosuke; Tazawa, Shota; Bratescu, Maria; Suda, Yoshiyuki; Sugawara, Hirotake

2004-09-01

449

Role of Acentric Displacements on the Crystal Structure and Second-Harmonic Generating Properties of RbPbCO3F and CsPbCO3F.  

PubMed

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 P6?m2 (crystal class 6?m2). Powder second-harmonic generation (SHG) measurements on RbPbCO3F and CsPbCO3F using 1064 nm radiation revealed an SHG efficiency of approximately 250 and 300 × ?-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

Tran, T Thao; Halasyamani, P Shiv; Rondinelli, James M

2014-06-16

450

Polarized infrared study on the structure of two-dimensional nanoclusters of partially fluorinated long-chain fatty acid salts at ambient and elevated temperatures  

NASA Astrophysics Data System (ADS)

Atomic force microscopy (AFM) images of the single monolayer of five partially fluorinated fatty acid salts [CF3(CF2)m(CH2)nCOO-]2Cd2+ [(m,n)=(7,10), (7,16), (7,22), (5,22), and (3,22)] transferred from aqueous Cd2+ subphase to solid substrate revealed that the molecules had assembled into monodispersed two-dimensional clusters of tens of nanometers, whose morphology developed systematically with (m,n). Polarized infrared measurements detected a corresponding change with (m,n) in the -(CF2)-m and -(CH2)-n orientation angles. It is found that the van der Waals interaction between the C-C-C trans zig-zag planes of adjacent hydrocarbon segments is the driving force for the cluster formation, while the overlapping interaction between the fluorocarbon tails of neighbor salt molecules is responsible for cluster compactness. Grazing incidence reflection absorption spectra of the (m,n)=(7,10) single monolayer recorded during temperature elevation from 25 to 150 °C show that heating has caused the hydrocarbon chain and the terminal C-CF3 axis to be gradually randomly oriented, while the carboxylate C2 symmetry axis and the fluorocarbon long axis to realign toward the substrate normal. It is discovered that the single monolayer has thermal memory and cyclic heating-cooling treatment can render an excellent thermal stability of 120 °C to the -(CH2)-10 and CF3(CF2)-7 orientations. The different thermal behavior of the corresponding five-layer Y-type LB films, reported by Naselli, Swalen, and Rabolt [J. Chem. Phys. 90, 3855 (1989)] was explained as due to the longitudinal interaction between the headgroups of adjacent layers.

Ren, Yanzhi; Iimura, Ken-Ichi; Kato, Teiji

2000-07-01

451

Nanocomposite Teflon AF 2400 films as tunable platforms for selective transport.  

PubMed

The performance of polymeric film-based sensors, separations, including extractions, depends on solute transport rates and selectivity. The membrane's chemical composition, its state (e.g, crystalline, glassy, rubbery), and its fractional free volume are all important in defining performance attributes. Other properties of films important in sensors are robustness in the environment, chemical inertness and biocompatibility, thermal stability, and optical transparency. With the long-term goal of selective transport/extraction based on molecular recognition, we have focused on fluorous media such as Teflon AF 2400. We present a novel approach to create nanocomposite Teflon AF 2400 films with the polymer in different states to facilitate permeation and fluorous selectivity in liquid phase transport. Films cast from stable suspensions of the fluorocarbon polymer Teflon AF 2400 (T(g) ? 240 °C), fluoroalkylsilane-modified solid, low polydispersity silica nanoparticles (FNPs: 116 nm diameter), and with or without a plasticizer (perfluorotripentylamine, FC-70) are macroscopically homogeneous. The nanocomposite films with glassy polymer absorb considerable solvent, CHCl(3), when in contact with solutions. Thus, the films are very permeable to solutes (toluene and octafluorotoluene) from CHCl(3) solution with poor selectivity for the fluorinated solute. Plasticized Teflon AF nanocomposite films show very low solvent sorption, improved fluorocarbon/hydrocarbon selectivity, and excellent transport rates. This is an unprecedented example demonstrating the effect of a plasticizer to create polymer nanocomposites with different chemical and barrier properties. The state of the polymer in the nanocomposites dictates chemical properties. The chemical properties dictate the transport behavior. In all cases, the films are dimensionally and thermally quite stable, making them ideal materials for applications in separations and sensors. PMID:23074985

Zhang, Hong; Wang, Sijia; Weber, Stephen G

2012-11-20

452

Controlling modulus and morphology of hydrogel tubes through surface modification.  

PubMed

Crosslinked, porous poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) (PHEMA-MMA) tubes were prepared in cylindrical glass molds using a new centrifugal casting process developed in our group. The resulting hydrogel tubes have a bi-phasic wall structure, with a spongy inner layer and a gel-like outer layer, the latter of which provides mechanical strength to the tube. While many factors influence wall morphology and, thus, mechanical properties, we focused on the effect of the surface properties of the glass mold in which tubes are synthesized. Specifically, we investigated the impact of a diverse set of silane modifications of the glass mold on tube morphology, elastic modulus and mold release. We treated activated glass surfaces with one of three alkoxysilanes having either ethoxy, amine or fluorocarbon end-groups. Silane-modified glass surfaces were found to be more hydrophobic than the unmodified glass mold, with the most hydrophobic surface being that of the fluorocarbon-terminated silane. The presence of the silane layer on the mold was confirmed by X-ray photoelectron spectroscopy and the stability of this modification was confirmed by examining the surface chemistry of the hydrogel tubes. The biphasic hydrogel tube wall structure was observed for all tubes, yet those tubes synthesized in unmodified molds had a cracked outer morphology, whereas those synthesized in silane-modified molds had a smooth outer morphology. This influenced the mechanical properties of the tubes where tubes synthesized in silane-modified molds had a significantly greater elastic modulus than those tubes synthesized in unmodified molds. Release from the molds was easiest with ethoxy- and amine-functionalized silane mold modifications. PMID:15109099

Enescu, Cristina; Shoichet, Molly S

2004-01-01

453

Controlling Nonspecific Protein Adsorption in a Plug-Based Microfluidic System by Controlling Interfacial Chemistry Using Fluorous-Phase Surfactants  

PubMed Central

Control of surface chemistry and protein adsorption is important for using microfluidic devices for biochemical analysis and high-throughput screening assays. This paper describes the control of protein adsorption at the liquid–liquid interface in a plug-based microfluidic system. The microfluidic system uses multiphase flows of immiscible fluorous and aqueous fluids to form plugs, which are aqueous droplets that are completely surrounded by fluorocarbon oil and do not come into direct contact with the hydrophobic surface of the microchannel. Protein adsorption at the aqueous–fluorous interface was controlled by using surfactants that were soluble in fluorocarbon oil but insoluble in aqueous solutions. Three perfluorinated alkane surfactants capped with different functional groups were used: a carboxylic acid, an alcohol, and a triethylene glycol group that was synthesized from commercially available materials. Using complementary methods of analysis, adsorption was characterized for several proteins (bovine serum albumin (BSA) and fibrinogen), including enzymes (ribonuclease A (RNase A) and alkaline phosphatase). These complementary methods involved characterizing adsorption in microliter-sized droplets by drop tensiometry and in nanoliter plugs by fluorescence microscopy and kinetic measurements of enzyme catalysis. The oligoethylene glycol-capped surfactant prevented protein adsorption in all cases. Adsorption of proteins to the carboxylic acid-capped surfactant in nanoliter plugs could be described by using the Langmuir model and tensiometry results for microliter drops. The microfluidic system was fabricated using rapid prototyping in poly(dimethylsiloxane) (PDMS). Black PDMS micro-fluidic devices, fabricated by curing a suspension of charcoal in PDMS, were used to measure the changes in fluorescence intensity more sensitively. This system will be useful for microfluidic bioassays, enzymatic kinetics, and protein crystallization, because it does not require surface modification during fabrication to control surface chemistry and protein adsorption.

Roach, L. Spencer; Song, Helen; Ismagilov, Rustem F.

2006-01-01

454

Composite propellant aluminum agglomeration reduction using tailored Al/PTFE particles  

NASA Astrophysics Data System (ADS)

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 ?m, ~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 ?m, 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 ?m coarse products, which are smaller than the original, average particle size and are also 66% smaller in diameter (96% by volume) than the 76 ?m 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.

Sippel, Travis R.

455

Calibration and Sequence Development Status for the Sample Analysis at Mars Investigation on the Mars Science Laboratory  

NASA Technical Reports Server (NTRS)

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.

Mahaffy, Paul R.

2012-01-01

456

Synthesis of hybrid inorganic/organic nitric oxide-releasing silica nanoparticles for biomedical applications  

NASA Astrophysics Data System (ADS)

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 ?mol 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.

Carpenter, Alexis Wells

457

Hepatic bilirubin uptake in the isolated perfused rat liver is not facilitated by albumin binding.  

PubMed Central

Bilirubin uptake by the liver is a rapid process of high specificity that has kinetic characteristics which suggest carrier-mediation. In the circulation, bilirubin is readily bound to albumin, from which it is extracted by the liver. Although several studies suggested that it is the small, unbound fraction of bilirubin which interacts with hepatocytes and is removed from the circulation, recent experiments have been interpreted as suggesting that binding to albumin facilitates ligand uptake. A liver cell surface receptor for albumin has been postulated. The present study was designed to examine directly whether albumin facilitates the hepatic uptake of bilirubin and whether uptake of bilirubin depends on binding to albumin. Rat liver was perfused with a protein-free fluorocarbon medium, and single-pass uptake of 1, 10, or 200 nmol of [3H]bilirubin was determined after injection as an equimolar complex with 125I-albumin, with 125I-ligandin, or free with only a [14C]sucrose reference. Uptake of 10 nmol of [3H]bilirubin was 67.5 +/- 3.7% of the dose when injected with 125I-albumin, 67.4 +/- 6.5% when injected with 125I-ligandin, and 74.9 +/- 2.4% when injected with [14C]sucrose (P greater than 0.1). At 200 nmol, uptake fell to 46.4 +/- 3.1% (125I-albumin) and 63.3 +/- 3.4% [( 14C]sucrose) of injected [3H]bilirubin (P less than 0.01), which suggests saturation of the uptake mechanism. When influx was quantitated by the model of Goresky, similar results were obtained. When [3H]bilirubin was injected simultaneously with equimolar 125I-albumin and a [14C]sucrose reference, there was no delay in 125I-albumin transit as compared with that of [14C]sucrose. This suggested that the off-rate of albumin from a putative hepatocyte receptor would have to be very rapid, which is unusual for high affinity receptor-ligand interaction. There was no evidence for facilitation of bilirubin uptake by binding to albumin or for interaction of albumin with a liver cell surface receptor. These results suggest that the hepatic bilirubin uptake mechanism is one of high affinity which can extract bilirubin from circulating carriers such as albumin, ligandin, or fluorocarbon.

Stollman, Y R; Gartner, U; Theilmann, L; Ohmi, N; Wolkoff, A W

1983-01-01

458

Hepatic bilirubin uptake in the isolated perfused rat liver is not facilitated by albumin binding  

SciTech Connect

Bilirubin uptake by the liver has kinetic characteristics which suggest carrier-mediation. Bilirubin is readily bound to albumin. A liver cell surface receptor for albumin has been postulated. The present study was designed to examine directly whether albumin facilitates the hepatic uptake of bilirubin and whether uptake of bilirubin depends on binding to albumin. Rat liver was perfused with a protein-free fluorocarbon medium, and single-pass uptake of 1, 10, or 200 nmol of (/sup 3/H)bilirubin was determined after injection as an equimolar complex with /sup 125/I-albumin, with /sup 125/I-ligandin, or free with only a (/sup 14/C)sucrose reference. Uptake of 10 nmol of (/sup 3/H)bilirubin was 67.5 +/- 3.7% of the dose when injected with /sup 125/I-albumin, 67.4 +/- 6.5% when injected with /sup 125/I-ligandin, and 74.9 +/- 2.4% when injected with (/sup 14/C)sucrose (P greater than 0.1). At 200 nmol, uptake fell to 46.4 +/- 3.1% (/sup 125/I-albumin) and 63.3 +/- 3.4% ((/sup 14/C)sucrose) of injected (/sup 3/H)bilirubin (P less than 0.01), which suggests saturation of the uptake mechanism. When influx was quantitated by the model of Goresky, similar results were obtained. When (/sup 3/H)bilirubin was injected simultaneously with equimolar /sup 125/I-albumin and a (/sup 14/C)sucrose reference, there was no delay in /sup 125/I-albumin transit as compared with that of (/sup 14/C)sucrose. This suggested that the off-rate of albumin from a putative hepatocyte receptor would have to be very rapid, which is unusual for high affinity receptor-ligand interaction. There was no evidence for facilitation of bilirubin uptake by binding to albumin or for interaction of albumin with a liver cell surface receptor. These results suggest that the hepatic bilirubin uptake mechanism is one of high affinity which can extract bilirubin from circulating carriers such as albumin, ligandin, or fluorocarbon.

Stollman, Y.R.; Gaertner, U.; Theilmann, L.; Ohmi, N.; Wolkoff, A.W.

1983-08-01

459

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

NASA Astrophysics Data System (ADS)

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.

Barry, Peter R.

460

Geochemical and mineralogical characteristics of ion-adsorption type REE mineralization in Phuket, Thailand  

NASA Astrophysics Data System (ADS)

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.

Sanematsu, Kenzo; Kon, Yoshiaki; Imai, Akira; Watanabe, Koichiro; Watanabe, Yasushi

2013-04-01

461

Efficient, environmentally acceptable method for waterproofing insulation material  

NASA Technical Reports Server (NTRS)

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.

Blohowiak, Kay Y. (Inventor); Krienke, Kenneth A. (Inventor); Olli, Larry K. (Inventor); Newquist, Charles W. (Inventor)

2000-01-01

462

The characterization of plasma-surface interactions using the inductively coupled gaseous electronics conference reference cell platform  

NASA Astrophysics Data System (ADS)

The ability to systematically vary the amount of plasma-surface interaction for any given plasma process can provide a novel approach to controlling the gas-phase plasma chemistry, the physical parameters of the plasma and the reaction pathways which govern etch and deposition at the sample surface. In this dissertation, such systematic methods to control plasma-surface interactions are explored during the processing of silicon, silicon dioxide (SiO2 ), polydimethyl siloxane (PDMS) and porous methylsilsequioxane (p-MSQ) films. These methods include processing as a function of chamber wall temperature, chamber dimension, feedgas chemistry, and sample porosity while simultaneously measuring the plasma gas-phase chemistry, the plasma density, and the reactions which occur on the sample surface, to determine how each effects the plasma system as a whole. When processing as a function of chamber wall temperature, results in tetrafluoromethane plasma show that increasing wall temperature decreases CF4 density while concurrently increasing CF4 vibrational temperature. The line-averaged vibrational temperature however, was found to remain at a steady state value above the chamber wall temperature while the CF4 vibrational temperature in the center of the discharge was calculated to be significantly higher. Using a modified gaseous electronics conference (GEC) reference cell, chamber dimension was found to significantly effect the etch rate of silicon dioxide as well as the fluorocarbon deposition rate due to variations of ion density and neutral flux. Specifically, low-energy ion assisted deposition was found to be the predominant mechanism governing fluorocarbon deposition while ion loss as a function of dimension, was established to be the rate limiting step for high energy reactive ion etch. The role of feedgas chemistry on plasma-surface interactions was also explored and revealed how different ratios of O2:CF 4 gas mixtures can significantly modify the processing rates and sample surface chemistry of a hybrid polydimethylsiloxane material. Depending on the percentage of oxygen admixed in the tetrafluoromethane feedgas, the etch could be tailored from energy dependent to energy independent. Tweaking the process in an inductively coupled plasma further improved the etch rate such that it was twice as high as those published in a capacitive plasma process. The resultant stoichiometry of the etched films was also found to depend on the feedgas chemistry as the refractive index of the material increased by 7% when pure oxygen was used and decreased by 6% when pure tetrafluoromethane was used. (Abstract shortened by UMI.)

Joseph, Eric Andrew

463

Remote plasma processing of thin film materials  

NASA Astrophysics Data System (ADS)

In this thesis, phenomena and mechanisms of remote plasma processes are investigated. The plasmas are spatial