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1

The fluorocarbon industry  

NASA Technical Reports Server (NTRS)

An overview of the history, production, and uses of fluorocarbons, the extent of leakage to the atmosphere, and the possibilities for developing or expanding the use of substitute products is presented. Some data are also included on the economic value and the work force related to fluorocarbon production and applications.

1975-01-01

2

Subcooled flow boiling of fluorocarbons  

E-print Network

A study was conducted of heat transfer and hydrodynamic behavior for subcooled flow boiling of Freon-113, one of a group of fluorocarbons suitable for use in cooling of high-power-density electronic components. Problems ...

Murphy, Richard Walter

1971-01-01

3

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. PMID:20643968

Dalvi, Vishwanath H.; Rossky, Peter J.

2010-01-01

4

Emulsions and microemulsions with a fluorocarbon phase  

Microsoft Academic Search

A phase III clinical study of a perfluorooctyl bromide emulsion demonstrated reduction and avoidance of donor blood transfusion in surgery. Novel fluorocarbon-in-water emulsions are being investigated, including emulsions highly stabilized by fluorocarbon–hydrocarbon diblocks and targeted emulsions for molecular imaging, diagnosis and drug delivery. Reverse water-in-fluorocarbon emulsions and microemulsions that have potential for pulmonary drug delivery are also being studied. Microemulsions

Marie Pierre Krafft; Alba Chittofrati; Jean G Riess

2003-01-01

5

Fluorinated diamond bonded in fluorocarbon resin  

SciTech Connect

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, Gene W. (Los Alamos, NM)

1982-01-01

6

Fluorinated diamond bonded in fluorocarbon resin  

SciTech Connect

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.

1982-08-10

7

Fluorocarbon adsorption in hierarchical porous frameworks  

NASA Astrophysics Data System (ADS)

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

Motkuri, Radha Kishan; Annapureddy, Harsha V. R.; Vijaykumar, M.; Schaef, H. Todd; Martin, Paul F.; McGrail, B. Peter; Dang, Liem X.; Krishna, Rajamani; Thallapally, Praveen K.

2014-07-01

8

Process for synthesizing a new series of fluorocarbon polymers  

NASA Technical Reports Server (NTRS)

Two-step process for preparing fluorocarbon materials includes - /1/ adding gaseous fluorine to a polyperfluoropolyene to create fluorocarbon radicals, with reactive sites at unsaturated carbon atoms, and /2/ introducing a monomer, after evacuation of fluorine gas, and allowing copolymerization with the free radicals.

Toy, M. S.

1970-01-01

9

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, Gene W. (Los Alamos, NM); Roybal, Herman E. (Santa Fe, NM)

1985-01-01

10

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

11

Submillimeter Absorption Spectroscopy of Fluorocarbon Plasmas  

NASA Astrophysics Data System (ADS)

Submillimeter (300 GHz to 1 THz) absorption spectroscopy is being developed as a diagnostic for measuring radical densities and temperatures in processing plasmas for microelectronics. Most molecules, radicals, and ions have transitions suitable for detection at these frequencies and the necessary spectroscopic data is available in the literature for determining the absolute radical densities. In addition, the narrow linewidths of < 10 kHz of these continuous-wave sources are suitable for measuring rotational, vibrational and translational temperatures of radicals. Initial measurements are being conducted with a backward-wave-oscillator (BWO) source and a liquid-He-cooled bolometer detector. Radical density measurements have been made in inductively and capacitively coupled GEC Reference Reactors. The influence of wafer coatings on plasma chemistry has been measured for several different fluorocarbon (C_4F_8, C_4F_6, and C_5F_8) / oxygen etching gas mixtures. In addition, a comparison of results obtained with the BWO and a new photomixer radiation source will be presented.

Benck, Eric; Golubiantnikov, Guerman; Fraser, Gerald; Plusquellic, David; Korter, Timothy; Lavrich, Rich; Bychkov, Vyatcheslav

2002-10-01

12

NMR analysis of a fluorocarbon copolymer  

SciTech Connect

Vinylidene fluoride (VF/sub 2/) can be copolymerized with chlorotrifluoroethylene (CTFE) in an aqueous emulsion using a peroxide chain initiator. The physical properties of the resulting fluorocarbon polymer depend on the ratio of VF/sub 2/ to CTFE and the randomness of the copolymerization. When CTFE and VF are polymerized in an approximately 3:1 mole ratio, the resulting polymer is soluble in acetone (and other solvents) at room temperature. Using proton and fluorine-19 NMR, the mole ratio of CTFE to VF/sub 2/, the emulsifier (perfluorodecanoate) concentration, and the randomness of copolymerization can be determined. A trifluorotoluene internal standard is added to a d/sub 6/-acetone solution of the fluoropolymer. Proton NMR is used to determine the amount of VF/sub 2/. Fluorine-19 NMR is used to measure the amount of emulsifier and the randomness of copolymerization. Each analysis requires about 5 minutes, and is quite precise, with relative standard deviations from 3 to 10% (10 replicates analyzed). In addition, the results from NMR analyses agree well with wet chemical analyses. 4 refs., 3 figs., 3 tabs.

Smith, R.E.; Smith, C.H.

1987-10-01

13

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

14

Developing Cross Section Sets for Fluorocarbon Etchants  

NASA Astrophysics Data System (ADS)

Successful modeling of plasmas used in materials processing depends on knowledge of a variety of collision cross sections and reaction rates, both within the plasma and at the surface. Electron-molecule collision cross sections are especially important, affecting both electron transport and the generation of reactive fragments by dissociation and ionization. Because the supply of cross section data is small and measurements are difficult, computational approaches may make a valuable contribution, provided they can cope with the significant challenges posed. In particular, a computational method must deal with the full complexity of low-energy electron-molecule interactions, must treat polyatomic molecules, and must be capable of computing cross sections for electronic excitation. These requirements imply that the method will be numerically intensive and thus must exploit high-performance computers to be practical. We have developed an ab initio computational method, the Schwinger multichannel (SMC) method, that possesses the characteristics just described, and we have applied it to compute cross sections for a variety of molecules, with particular emphasis on fluorocarbon and hydrofluorocarbon etchants used in the semiconductor industry. A key aspect of this work has been an awareness that cross section sets, validated when possible against swarm data, are more useful than individual cross sections. To develop such sets, cross section calculations must be integrated within a focused collaborative effort. Here we describe electron cross section calculations carried out within the context of such a focused effort, with emphasis on fluorinated hydrocarbons including CHF3 (trifluoromethane), c-C4F8 (octafluorocyclobutane), and C2F4 (tetrafluoroethene).

Winstead, Carl; McKoy, Vincent

2002-10-01

15

Mixed fluorocarbon/hydrocarbon molecular dowels help protect concentrated fluorocarbon emulsions with large size droplets against coalescence.  

PubMed

Mixed fluorocarbon/hydrocarbon amphiphiles, the so-called molecular dowels, have previously been reported to strongly stabilize concentrated (90% w/v, i.e. 47% w/v) submicronic size perfluorooctyl bromide emulsions emulsified by egg yolk phospholipids. The dowel molecules, used in equimolar amounts with phospholipids, enable the preparation of emulsions with large-sized particles which are impossible to obtain with phospholipids alone. We report here that molecular dowels (C6F13C10H21, F6H10) also hinder droplet coalescence induced by mechanical stress in sterilized emulsions with average particle sizes ranging from ca 1 to 16 microns. In contrast, the addition of equimolar amounts of perfluorodecyl bromide was found to have little influence on these emulsions' resistance to mechanical stress. This is consistent with the view that mixed fluorocarbon/hydrocarbon dowels are held in the interfacial film and reinforce its cohesion with the fluorocarbon phase. PMID:7849932

Cornélus, C; Krafft, M P; Riess, J G

1994-01-01

16

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

17

Fluoro-Carbonate Solvents for Li-Ion Cells  

SciTech Connect

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. Conductivity of single and mixed fluoro carbonate electrolytes containing 1 M LiPF{sub 6} was measured at different temperatures. These electrolytes did not freeze at -40 C. We are evaluating currently, the irreversible 1st cycle capacity loss in carbon anode in these electrolytes and the capacity loss will be compared to that in the conventional electrolytes. Voltage stability windows of the electrolytes were measured at room temperature and compared with that of the conventional electrolytes. The fluoro-carbon electrolytes appear to be more stable than the conventional electrolytes near Li voltage. Few preliminary electrochemical data of the fluoro-carbonate solvents in full cells are reported in the literature. For example, some of the fluorocarbonate solvents appear to have a wider voltage window than the conventional electrolyte solvents. For example, methyl 2,2,2 trifluoro ethyl carbonate containing 1 M LiPF{sub 6} electrolyte has a decomposition voltage exceeding 6 V vs. Li compared to <5 V for conventional electrolytes. The solvent also appears to be stable in contact with lithium at room temperature.

NAGASUBRAMANIAN,GANESAN

1999-09-17

18

Gain and loss mechanisms in fluorocarbon plasmas  

NASA Astrophysics Data System (ADS)

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

Nelson, Caleb Timothy

19

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

20

Novel Ethanol-in-Fluorocarbon Microemulsions for Topical Genetic Immunization  

Microsoft Academic Search

Purpose. Traditionally, vaccines have been administered by needle injection. Topical immunization through the intact skin with either protein- or DNA-based vaccines has attracted much attention recently. We sought to enhance the immune responses induced by DNA-based vaccines after topical application by developing novel ethanol-in-fluorocarbon (E\\/F) microemulsion systems to aid in the delivery of plasmid DNA (pDNA).

Zhengrong Cui; William Fountain; Michael Clark; Michael Jay; Russell J. Mumper

2003-01-01

21

Improved control over particle sizes and stability of concentrated fluorocarbon emulsions by using mixed fluorocarbon/hydrocarbon molecular dowels.  

PubMed

The use of a surfactant system consisting in equimolar amounts of egg yolk phospholipids and of a mixed fluorocarbon/hydrocarbon amphiphile (C8H17CH = CHC8F17) allows the preparation of concentrated (90% w/v, i.e. 47% v/v) emulsions of perfluorooctyl bromide (perflubron), with average particle sizes ranging from 0.12 to 16 microns post-sterilization, depending on the surfactant/fluorocarbon ratio. Emulsion droplet diameters varied linearly as a function of the emulsifier's concentration, thus allowing easy pre-determination of the emulsion's average particle size. Excellent stability was observed for the dowel-containing emulsions for at least 6 months at 40 degrees C over the whole domain of particle sizes investigated. PMID:7849921

Cornélus, C; Krafft, M P; Riess, J G

1994-01-01

22

Reverse water-in-fluorocarbon emulsions as a drug delivery system: an in vitro study  

Microsoft Academic Search

Liquid fluorocarbons with high gas-dissolving capacity, high fluidity, low surface tension, exceptional biological inertness, are in clinical trials for the treatment of acute respiratory failure by liquid ventilation. Fluorocarbons are able to reopen collapsed alveoli and facilitate the exchange of the respiratory gases. They also constitute a promising carrier for administration of drugs via the pulmonary route. Since pharmaceuticals are

Véronique M Sadtler; Marie Pierre Krafft; Jean G Riess

1999-01-01

23

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

24

Fluorocarbon 113 exposure and cardiac dysrhythmias among aerospace workers.  

PubMed

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

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

1992-01-01

25

Fluorocarbon 113 exposure and cardiac dysrhythmias among aerospace workers  

SciTech Connect

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

Egeland, G.M.; Bloom, T.F.; Schnorr, T.M.; Hornung, R.W.; Suruda, A.J.; Wille, K.K. (National Institute for Occupational Safety and Health, Cincinnati, OH (United States))

1992-01-01

26

Effect of fluorocarbon molecules confined between sliding self-mated PTFE surfaces.  

PubMed

We report on the frictional response and atomic process that occur when molecular fluorocarbon molecules of varying lengths are sheared between two polytetrafluoroethylene (PTFE) surfaces. The thicknesses of the molecular layers are also varied. The approach is classical molecular dynamics simulations using a reactive bond-order potential parametrized for fluorocarbons. The results indicate that the presence of the molecules has a significant impact on the measured friction and wear of the surfaces, and that this impact depends on the nature of the fluorocarbon molecules and the thickness of the molecular film. The molecular mechanisms responsible for these differences are presented. PMID:21728348

Barry, Peter R; Chiu, Patrick Y; Perry, Scott S; Sawyer, W Gregory; Phillpot, Simon R; Sinnott, Susan B

2011-08-16

27

Generation of fluorocarbon and hydrocarbon hybrid gemini surfactants controlled by micellar miscibility.  

PubMed

Hybrid surfactants were generated through the simple mixing of fluorocarbon and hydrocarbon gemini surfactants in aqueous solutions at 25°C. Disulfide exchange between the disulfide in the spacer chain occurred in the mixed micelles. However, the generation of hybrid gemini surfactants was particularly inhibited by the addition of salt. The suppression of the electrostatic repulsion between the hydrophilic headgroups led to the close packing of the hydrophobic chains in the micelles, resulting in the increased immiscibility of the fluorocarbon and hydrocarbon surfactants. On the other hand, when fluorocarbon-fluorocarbon or hydrocarbon-hydrocarbon surfactants were mixed, equilibrium with a 1:2 ratio of symmetric and dissymmetric gemini surfactants was attained after incubation for 24 h. PMID:23357813

Asakawa, Tsuyoshi; Ozawa, Tadahiro; Ohta, Akio

2013-01-01

28

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. PMID:3004555

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

1986-01-01

29

Potential use of fluorocarbons in lung surfactant therapy.  

PubMed

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

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

2007-01-01

30

Fluorocarbon-encapsulated oxygen bubbles for blood oxygenation use: An experimental study  

Microsoft Academic Search

This paper is concerned with a novel class of oxygenators which Li and Asher first proposed and called “liquid membrane oxygenators.”\\u000a They are different from usual bubble blood oxygenators in that oxygen bubbles are individually encapsulated by a liquid fluorocarbon\\u000a membrane and dispersed in blood, instead of bare oxygen bubbles normally used. The fluorocarbon membrane's role is to prevent\\u000a direct

Yasuhiko H. Mori; Keiji Kaminaga; Takashi Ando

1990-01-01

31

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

32

Developments of Basic Researches on Fluorocarbon Plasmas for Material Processing 3. Mechanism of Fluorocarbon Gas Dissociation in Plasma  

NASA Astrophysics Data System (ADS)

To investigate the mechanism of C4F8 dissociation, we made extensive measurements of electrons and radicals, as well as a theoretical study. These showed that the amount of light fluorocarbon radicals increased with increasing electron density. The dissociation of C4F8 was analyzed by using rate equations. The total dissociation rate coefficient of C4F8 was 1×10-8cm3/s, and CF2 radicals were mainly generated from products of C4F8 dissociation. F was mainly generated from CF2 by electron-impact dissociation and lost by pumping. We estimate that the C2F4 density was roughly comparable to the densities of CF and CF3, and that the surface loss probability of C2F4 increased with increasing electron density.

Hayashi, Hisataka; Sekine, Makoto

33

Large fluorocarbon ions can contribute to film growth during plasma etching of silicon  

NASA Astrophysics Data System (ADS)

The preferential etching of SiO2 over Si in fluorocarbon plasmas occurs in part through the growth of a fluorocarbon layer. Large CxFy+,0 (x>1) ions and radicals have been observed in etching fluorocarbon plasmas, but their role in the etching processes has not been clearly identified. Here we use mass-selected 5-200 eV C3F5+ and C2F4+ ion beams to form nanometer thick fluorocarbon and SixCyFz films on H-Si(100). Monochromatic x-ray photoelectron spectroscopy (XPS) shows that the average elemental and chemical content of the deposited film is nearly independent of ion identity and kinetic energy. The chemical nature of the fluorocarbon film instead is controlled largely by surface chemical and diffusion processes. However, ion energy and structure do control the fluorocarbon film morphology. Atomic force microscopy shows that 200 eV C3F5+ ion impact forms large oblong pits in the Si substrate that are approx30 nm deep and approx200 nm across. No large pits are observed in the Si substrate for 25 eV C3F5+ bombardment. XPS depth profiles of the films depend strongly upon ion energy and structure where the spatial distribution of the F depth profile increases with incident ion energy for both C3F5+ and C2F4+. Higher F content is found deeper in the surface and the SixCyFz buried interface is thickest at higher ion energies. These results are discussed in terms of the role of large ions and radicals in etching fluorocarbon plasmas.

Fuoco, Erick R.; Hanley, Luke

2002-07-01

34

Investigations of the environmental acceptability of fluorocarbon alternatives to chlorofluorocarbons.  

PubMed

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

McFarland, M

1992-02-01

35

Investigations of the environmental acceptability of fluorocarbon alternatives to chlorofluorocarbons.  

PubMed Central

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

McFarland, M

1992-01-01

36

Brillouin enhanced four-wave mixing with the liquid fluorocarbon  

NASA Astrophysics Data System (ADS)

Stimulated Brillouin Scattering (SBS) is a nonlinear optical effect that is broadly used for correcting the beam quality of laser beams, their mode control, amplification and phase conjugation. Two factors are essential when it comes to selection of the nonlinear medium for SBS, its efficiency or gain coefficient and safety. For example, a low SBS gain coefficient in the fluorocarbon liquid C8F18 is at least one order of magnitude lower than other nonlinear media, typically limits its application in high-power laser systems. However, highly purified C8F18 is a very safe and stable nonlinear medium, and in combination with its high optical breakdown threshold, has become attractive for many practical applications. This paper discusses a phase conjugate mirror (PCM) using the SBS effect in C8F18. A PCM reflectivity of better than 90% has been achieved in an optimized experimental geometry of the incoming beam. The output energy of the phase conjugated pulse linearly increased with the energy of the input pulse beyond a threshold level of about 3.3 mJ. The estimated slope efficiency is about 95%. For weak signal amplification, we have realized greater than 105 amplification with Brillouin enhanced four wave mixing (BEFWM) with an input signal at the level of several nJs. A reflected energy as high as 11 mJ has been achieved with a 400 ?J incoming input signal. Further lowering of the signal energy should result in a higher amplification.

Wu, Frank F.

2012-02-01

37

Volume increase on conmicellization of fluorocarbon and hydrocarbon surfactants as evidence for the mutal phobicity in conmicelles  

SciTech Connect

The molal volume of mixed neos detergent and sodium tetradecyl sulfate micelles increased upon conmicellization. This behavior is similar to the volume increase observed when bulk fluorocarbons and hydrocarbons are mixed. This finding demonstrates the existence of the mutual phobicity between fluorocarbons and hydrocarbon chains in small systems such as micelles. 11 references.

Funasaki, N.; Hada, S.

1980-07-10

38

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

39

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

SciTech Connect

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

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

2004-09-21

40

Nanostructures in water-in-CO2 microemulsions stabilized by double-chain fluorocarbon solubilizers.  

PubMed

High-pressure small-angle neutron scattering (HP-SANS) studies were conducted to investigate nanostructures and interfacial properties of water-in-supercritical CO2 (W/CO2) microemulsions with double-fluorocarbon-tail anionic surfactants, having different fluorocarbon chain lengths and linking groups (glutarate or succinate). At constant pressure and temperature, the microemulsion aqueous cores were found to swell with an increase in water-to-surfactant ratio, W0, until their solubilizing capacities were reached. Surfactants with fluorocarbon chain lengths of n = 4, 6, and 8 formed spherical reversed micelles in supercritical CO2 even at W0 over the solubilizing powers as determined by phase behavior studies, suggesting formation of Winsor-IV W/CO2 microemulsions and then Winsor-II W/CO2 microemulsions. On the other hand, a short C2 chain fluorocarbon surfactant analogue displayed a transition from Winsor-IV microemulsions to lamellar liquid crystals at W0 = 25. Critical packing parameters and aggregation numbers were calculated by using area per headgroup, shell thickness, the core/shell radii determined from SANS data analysis: these parameters were used to help understand differences in aggregation behavior and solubilizing power in CO2. Increasing the microemulsion water loading led the critical packing parameter to decrease to ~1.3 and the aggregation number to increase to >90. Although these parameters were comparable between glutarate and succinate surfactants with the same fluorocarbon chain, decreasing the fluorocarbon chain length n reduced the critical packing parameter. At the same time, reducing chain length to 2 reduced negative interfacial curvature, favoring planar structures, as demonstrated by generation of lamellar liquid crystal phases. PMID:23701401

Sagisaka, Masanobu; Iwama, Shuho; Ono, Shinji; Yoshizawa, Atsushi; Mohamed, Azmi; Cummings, Stephen; Yan, Ci; James, Craig; Rogers, Sarah E; Heenan, Richard K; Eastoe, Julian

2013-06-25

41

Reverse water-in-fluorocarbon emulsions and microemulsions obtained with a fluorinated surfactant  

Microsoft Academic Search

Neat fluorocarbons (FCs) are being investigated for pulmonary delivery of drugs and genes, triggering interest on reverse water-in-fluorocarbon emulsions as delivery systems for hydrophilic bioactive materials to the lung. In this paper we examine the ability of a series of perfluoroalkylated amphiphiles with a dimorpholinophosphate polar head group, CnF2n+1(CH2)mOP(O)[N(CH2CH2)2O]2 (FnHmDMP, n = 4, 6, 8, 10 and m = 2,

Hélène M. Courrier; Thierry F. Vandamme; Marie Pierre Krafft

2004-01-01

42

A fluorocarbon plastic scintillator for neutron detection: Proof of concept  

NASA Astrophysics Data System (ADS)

The fast neutron nuclear reactions, such as 19F(n, ?)16N and 19F(n, p)19O, can be used to detect highly energetic neutrons due to their energy thresholds above which these activation reactions can occur. This was recently shown (Gozani et al., 2011 [2]) as a means to detect concealed nuclear materials via the detection of the high energy (?3 MeV) prompt neutrons emitted during the photofission process. Fluorine-loaded scintillation detectors, such as inorganic BaF2 and CaF2, and non-hydrogenous fluorocarbon (FC) liquid scintillators, such as Saint-Gobain BC-509 and Eljen Technology EJ-313, are possible candidates. The latter was selected and implemented in the above mentioned reference. In our paper, we propose a new pentafluorostyrene-based plastic scintillator (F-plastic) which can be a good alternative to the abovementioned scintillators. The fluorine content of F-plastic is equal to 3.73×1022 atoms/cm3, and the F/H ratio is 1.66. The fluorescence and radioluminescence spectra of the F-plastic display an emission maximum centered approximately at 420 nm. The light output measured for gamma rays is 3100±300 photons/MeV, which is approximately 30% of the light output of the standard EJ-200 plastic scintillator and is similar to EJ-313. The response of the F-plastic to neutrons and gamma rays is presented and compared to the EJ-200 scintillator. Additionally, the n/? pulse shape discrimination (PSD) was measured and showed improvement of the discrimination at neutron energies as high as 3 MeV.

Hamel, Matthieu; Sibczynski, Pawel; Blanc, Pauline; Iwanowska, Joanna; Carrel, Frédérick; Syntfeld-Ka?uch, Agnieszka; Normand, Stéphane

2014-12-01

43

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

44

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

NASA Astrophysics Data System (ADS)

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 particle physics experiments. Systems to circulate and purify saturated fluorocarbon Cherenkov radiator vapours often rely on thermodynamic evaporation-condensation cycles similar to those used in refrigeration. Their use as evaporative refrigerants was pioneered for the ATLAS silicon tracker, and they are now also used as evaporative coolants in ALICE and TOTEM and as liquid coolants in ATLAS and CMS. Ultrasonic techniques for vapour phase analysis of fluorocarbon mixtures—developed for the SLAC SLD barrel CRID radiator during the 1980s as an alternative to UV refractometry are again under development for the ATLAS tracker evaporative cooling system. Examples of fluorocarbon circulation systems, together with purification and analysis techniques for these versatile fluids are mentioned.

Hallewell, G.

2011-05-01

45

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

46

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

47

Estimation of second-, third- and fourth-order nonlinearity parameters for specific fluorocarbon drug-delivering nanosystems  

Microsoft Academic Search

The nonlinear B\\/A, C\\/A and D\\/A are new parameters in ultrasound fluorocarbon nanosystem characterisation. In this article, all the three parameters are estimated for specific fluorocarbons, such as perfluorohexane (C6F14), perfluoroheptanes (C7F16), perfluoro-1-butyl tetrahydrofuran (C8F16O), perfluoro octanes (C8F18), perfluorodecalin (C10F18), perfluorodichloro octane (C8F16Cl2) and perfluorooctyl bromide (C8F17Br) through their experimental ultrasonic velocity for different temperatures. The fluorocarbons under study are

K. Arockia Jayalatha; J. Amoros; S. Ravi

2011-01-01

48

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

49

Overview of progress in the fluorocarbon approach to in vivo oxygen delivery.  

PubMed

The development of fluorocarbon-based oxygen carriers has experienced rapid progress over the past few years. Fluosol has been approved for use during percutaneous transluminal coronary angioplasty (PTCA) for high-risk patients. Its clinical evaluation is being pursued as an adjunct to cancer therapy and for treatment of myocardial infarction in conjunction with thrombolytic therapy. O2-delivery efficacy has been achieved with the development of the new highly concentrated (4 to 5 times more concentrated than Fluosol), fluid, emulsions of perfluorooctyl bromide (perflubron), trade-named Oxygen. The stability of fluorocarbon emulsions has also improved considerably and the new emulsions can be stored unfrozen and are ready for use. The side-effect profile of these emulsions has been characterized as being the normal response of the body's phagocytes to the injection of particles, a response that is considered physiological rather than pathological in nature; it involves some products of arachidonic acid metabolism and can be controlled pharmacologically. Means of further stabilizing fluorocarbon emulsions, involving molecular-diffusion-controlling additives or fluorinated surfactants, including mixed fluorocarbon-hydrocarbon compounds, have been devised. Increased control over in vivo particle recognition, intravascular persistence and side effects, and at adapting emulsion characteristics to specific applications, is being investigated. The range of therapeutic applications is expanding. The concentrated emulsions will be able to serve as a temporary red blood cell substitute in many situations. Acute normovolemic hemodilution with fluorocarbon emulsions, used in conjunction with homologous predonation and other blood-sparing techniques, should afford greater flexibility, increase the margin of safety, and reduce or alleviate the need for autologous blood transfusion during surgical procedures. Fluorocarbon applications in the cardiovascular field include use during PTCA, for cardioplegia and reperfusion, and the treatment of myocardial infarction. Significant tumor growth delay has been achieved when concentrated emulsions are used in conjunction with cancer radio- or chemotherapy. Liquid ventilation has potential as a unique treatment for the adult and infant respiratory distress syndromes and for drug delivery. The radiopaque and versatile perflubron can also be used in contrast agents for diagnosis with computed X-ray tomography, magnetic resonance imaging and ultrasound, allowing the early detection and staging of cancer. Other potential applications investigated include the treatment of cerebral ischemia, organ and limb preservation, use as a tamponade during retinal repair, etc. PMID:1391434

Riess, J G

1992-01-01

50

Interaction between a Solute Molecule and a Fluorocarbon Bonded Layer in Reversed-Phase High-Performance Liquid Chromatography.  

PubMed

Glassesand silica-gel packings modified with fluorocarbon and hydrocarbon silylation agents were prepared to investigate the separation mechanism of a fluorocarbon bonded layer in reversed-phase high-performance liquid chromatography (RP-HPLC). On the hydrocarbon layer the contact angles of benzene (Be) and hexafluorobenzene (FB) decreased with increasing carbon chain length of the modifier, and the mobile phase (MP) was independent of the modifier. The fluorocarbon layer gave a larger contact angle for each liquid than the hydrocarbon layer. The retention factor, k, of Be and FB on hydrocarbon packings increased with decreasing contact angle. It was demonstrated that the separation of Be and FB on hydrocarbon packings is caused by solvophobic interaction between solute molecules and the stationary layer. In contrast, k increased with increasing contact angle at the fluorocarbon layer. The retention of Be and FB on fluorocarbon packings may be attributed to the penetration of the solute molecules from the mobile phase into the fluorocarbon stationary layer. Copyright 1999 Academic Press. PMID:10550249

Kamiusuki; Monde; Nakayama; Yano; Yoko; Konakahara

1999-12-01

51

Comparison of stratospheric ozone destruction by fluorocarbons 11, 12, 21, and 22  

NASA Technical Reports Server (NTRS)

Measured photoabsorption cross sections for fluorocarbons (FC) 11, 12, 21, and 22 are presented for the wavelength region from 1740 A to about 2200 A. Solar radiation in this region dissociates these molecules in the stratosphere releasing atomic chlorine which participates in catalytic reactions that destroy ozone. Photolysis by solar UV is the only known loss mechanism for FC11 and FC12. However, FC21, and FC22 also react with OH in the troposphere reducing the amount of ground level releases which reach the stratosphere. Calculations comparing the steady state stratospheric C1X due to equal release rates of fluorocarbons 11, 12, 21, and 22 are presented using a range of OH profiles and eddy diffusion coefficients. These calculations indicate approximately a factor of 20 to 450 less C1X in the stratosphere for FC21 and a factor of 40 to 130 for FC22, compared to an equal release rate of FC11 and FC12.

Robbins, D. E.; Stolarski, R. S.

1976-01-01

52

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

53

Velocity of sound measurements in gaseous per-fluorocarbons and their custom mixtures  

E-print Network

An inexpensive sonar instrument was prepared for measurements of sound velocity in two fluorocarbon vapors; per-fluoro-n-propane (C3F8), per-fluoro-n-butane (C4F10), and their custom mixtures. The apparatus, measurement principle and instrument software are described. All sound velocity measurements in per-fluorocarbons were made in the low pressure range between 0.01 and 0.4 MPa, and at temperatures between 253 and 303 K. The purity of the C3F8 and C4F10 samples was checked using gas chromatography. Uncertainties in the speed of sound measurements were better than ± 0.1 %. Comparisons were made with theoretical predictions of sound velocity for the two individual components. The instrument was then used for concentration monitoring of custom C3F8/C4F10 mixtures.

Vacek, V; Lindsay, S

2000-01-01

54

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

Microsoft Academic Search

The structure, orientation, and formation of amphiphilic -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 -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

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

2010-01-01

55

Adhesion and neurite development of cortical neurons on micropatterns of polyethylenimine and fluorocarbon  

Microsoft Academic Search

This study aims on the preparation of isolated islands of cortical neurons on modified glass surfaces. Isolated islands of cortical neurons were obtained with a combination of neuron-adhesive polyethylenimine (PEI) and neuron-repellent plasma-deposited fluorocarbon (FC). Neurite development and fasciculation of interconnecting neurites between PEI-coated areas was studied. The patterns consisted of PEI-coated wells (diameter 150 ?m) which were initially etched

T. G. Ruardij; M. H. Goedbloed; W. L. C. Rutten

2000-01-01

56

Fluidization of a Dipalmitoyl Phosphatidylcholine Monolayer by Fluorocarbon Gases: Potential Use in Lung Surfactant Therapy  

Microsoft Academic Search

Fluorocarbon gases (gFCs) were found to inhibit the liquid-expanded (LE)\\/liquid-condensed (LC) phase transition of dipalmitoyl phosphatidylcholine (DPPC) Langmuir monolayers. The formation of domains of an LC phase, which typically occurs in the LE\\/LC coexistence region upon compression of DPPC, is prevented when the atmosphere above the DPPC monolayer is saturated with a gFC. When contacted with gFC, the DPPC monolayer

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

2006-01-01

57

Pyrolysis and laser ablation of plasma-polymerized fluorocarbon films: Effects of gold particles  

NASA Astrophysics Data System (ADS)

Plasma-polymerized fluorocarbon (PPFC) films were analyzed by thermogravimetric analysis (TGA), direct pyrolysis/mass spectrometry, and laser-ablation/electron-impact mass spectrometry. Fourier transform mass spectrometry was used to detect products. The films were made by plasma polymerizing tetrafluoroethylene in an argon plasma. Two types of films were studied: with and without fine gold particles incorporated in the PPFC films. TGA showed that gold-containing films decompose more rapidly and at lower temperature with increasing gold content. Pyrolysis products were determined as a function of temperature. The predominant positive product ions, using 20 eV electron-impact ionization, were C2F4+, CF3+ and a distribution of higher-mass unsaturated fluorocarbon species, CnFm+, up to at least n=14 and m?n+1. The predominant negative ions, formed by electron attachment, were also unsaturated fluorocarbon ions which extended up to 1145 u in mass. These species are different from those observed from polytetrafluoroethylene pyrolysis. No dependence of the positive-ion mass spectral distributions of pyrolysis products on gold content of the films was observed. However, the negative-ion pyrograms had a dramatically different temperature dependence for films with and without gold. The results imply that the gold-containing films have regions of lower molecular weight, and a possible formation mechanism is suggested. Laser ablation formed low-mass neutral fluorocarbon species. Ablation of the gold-containing film under direct laser ionization conditions (higher laser power), produced a spectrum resembling the pyrolysis spectrum, suggesting that the gold particles affect the mechanism of the ablation.

Creasy, William R.; Zimmerman, Jeffrey A.; Jacob, Wolfgang; Kay, Eric

1992-09-01

58

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

59

Histamine Release Associated with Intravenous Delivery of a Fluorocarbon-Based Sevoflurane Emulsion in Canines  

PubMed Central

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

JOHNSON, REBECCA A.; SIMMONS, KEN T.; FAST, JONATHAN P.; SCHROEDER, CARRIE A.; PEARCE, ROBERT A.; ALBRECHT, RALPH M.; MECOZZI, SANDRO

2011-01-01

60

Release and fate of fluorocarbons in a shredder residue landfill cell: 1. Laboratory experiments.  

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 use laboratory experiments to estimate fluorocarbon release and attenuation processes in a monofill shredder residue (SR) landfill cell. Waste from the open SR landfill cell at the AV Miljø landfill in Denmark was sampled at three locations. The waste contained 1-3% metal and a relatively low fraction of rigid polyurethane (PUR) foam particles. The PUR waste contained less blowing agent (CFC-11) than predicted from a release model. However, CFC-11 was steadily released in an aerobic bench scale experiment. Anaerobic waste incubation bench tests showed that SRSR produced significant methane (CH(4)), but at rates that were in the low end of the range observed for municipal solid waste. Aerobic and anaerobic batch experiments showed that processes in SRSR potentially can attenuate the fluorocarbons released from the SRSR itself: CFC-11 is degraded under anaerobic conditions with the formation of degradation products, which are being degraded under CH(4) oxidation conditions prevailing in the upper layers of the SR. PMID:20435458

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

2010-11-01

61

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

SciTech Connect

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

Mitkin, V.N.; Galkin, P.S.; Denisova, T.N. [and others

1998-07-01

62

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

63

Effect of two hydrocarbon and one fluorocarbon surfactant mixtures on the surface tension and wettability of polymers.  

PubMed

The advancing contact angle of water, formamide and diiodomethane on polytetrafluoroethylene (PTFE) and polymethyl methacrylate (PMMA) surfaces covered with the film of ternary mixtures of surfactants including p-(1,1,3,3-tetramethylbutyl) phenoxypoly(ethyleneglycols), Triton X-100 (TX100) and Triton X-165 (TX165) and the fluorocarbon surfactants, Zonyl FSN-100 (FSN100) or Zonyl FSO-100 (FSO100) was measured. The obtained results were used for the surface tension of PTFE and PMMA covered with this film determination from the Young equation on the basis of van Oss et al. and Neumann et al. approaches to the interfacial tension. The surface tension of PTFE and PMMA was also determined using the Neumann et al. equation and the contact angle values for the aqueous solutions of the above mentioned ternary surfactants mixtures which were taken from the literature. As follows from our calculations mainly the presence of the fluorocarbon surfactant in the mixture considerably changes the surface properties of PTFE and PMMA causing that in contrast to hydrocarbon surfactants and their mixtures there is no linear dependence between adhesion and surface tension in the whole range of concentration of the ternary mixtures of surfactants including the fluorocarbon one. The behavior of fluorocarbon surfactants at the polymer-air and polymer-water interfaces is quite different from those of hydrocarbons. In the case of fluorocarbon surfactants not only adsorption but also sorption can occur on the polymer surface. PMID:24407675

Szymczyk, Katarzyna; González-Martín, Maria Luisa; Bruque, Jose Morales; Ja?czuk, Bronis?aw

2014-03-01

64

The design and development of improved fluorocarbon-based products for use in medicine and biology.  

PubMed

Fluorocarbons and other highly fluorinated materials offer considerable potential in diagnosis and therapeutics due to their unique physical properties, chemical inertness, capacity to transport oxygen and drugs, and ability to function as contrast agents. Applications such as hemodilution and organ preservation, cancer diagnosis and chemotherapy, x-ray imaging of the lymph nodes and magnetic resonance imaging of the GI tract, cardioplegia and reperfusion, the treatment of myocardial ischemia and respiratory distress syndrome, as well as drug delivery, all obviously require different product characteristics, calling for an array of products which may range from different neat fluorocarbons to diversely formulated emulsions, or fluorinated vesicles. Substantial progress has been made in terms of emulsion efficacy and stability. Stable, ready-to-use, concentrated, though fluid, injectable emulsions have now been developed. Small doses of such emulsions were demonstrated to be highly efficient in tissue oxygenation. Commercial-scale manufacturing including heat sterilization of these emulsions have been achieved. Some of the side-effects, which generally relate to the normal response of the organism to injected particles, have been reduced, and their mechanism determined. Further efforts will undoubtedly be devoted to understanding and adjusting emulsion properties for optimal efficacy in each identified application and to maximizing benefit vs side-effect ratio. Our ability to modulate in vivo recognition, intravascular persistence and subsequent biodistribution of fluorocarbon droplets, vesicles and other particulate matter in the organism is still in its infancy. Proper control of these characteristics would further extend the potential of such products for medical uses. It is essential that no effort be spared to increase our general understanding of their physicochemical properties and in vivo "physiology". PMID:8087244

Riess, J G

1994-01-01

65

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.

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

2010-04-01

66

Influence on hydrophobicity of silicone rubber surface by introducing fluorocarbon functional groups  

NASA Astrophysics Data System (ADS)

Hydrophobic modification on surface of silicone rubber (SIR) by CF4 radio frequency inductively coupled plasma is discussed. Static contact angle, atomic force microscopy and X-ray photoelectron spectroscopy were used in characterizing the hydrophobic property, surface appearance and chemical composition of the modified SIR. The results show that the improvement of surface hydrophobic property on modified SIR is attributed to the introduction of fluorocarbon functional groups (C-CF n , n = 1, 2, 3) and fluosilicic structures (Si-F and Si-F2) during the treatment.

Gao, Song-Hua; Gao, Li-Hua

2014-09-01

67

Disappearance of fuel hydrazine vapors in fluorocarbon-film environmental chambers. Experimental observations and kinetic modeling  

SciTech Connect

Fluorocarbon-film environmental chambers, of the type often employed in air pollution studies, have been used to investigate the stability of the fuel hydrazines (hydrazine, methylhydrazine, and 1,1-dimethylhydrazine) with respect to atmospheric oxidation. These studies have shown that the observed disappearance of fuel hydrazine vapors in these chambers is caused by physical loss processes rather than oxidation. Vapor-phase decay is affected by chamber size, water content of the matrix gas, and previous chamber experiments. A kinetic model has been developed that incorporates adsorption, permeation, and surface site concentration to fit the observed decay data.

Stone, D.A.; Wiseman, F.L.; Kilduff, J.E.; Koontz, S.L.; Davis, D.D.

1989-03-01

68

Study on modification process of photoresist by fluorocarbon ions and radicals  

NASA Astrophysics Data System (ADS)

Etching processes for fabricating high-aspect ratio patterns with nano-scale accuracy are desired in such as a contract hole etching for the silicon dioxide that is used as a dielectric passivation layer over MOSFETs. Photoresists (PR) are indispensable for pattern formation by lithography and for masking of pattern-transfer etching processes. However, the ArF PR have poor tolerability against the process plasma and they may often be deformed to cause line edge roughness, striation, and twisting for the etched features. To overcome these problems and realize sophisticated etching process, we had investigated the reaction of ArF PR with mass-separated fluorocarbon ions, i.e. CFx^+ (x=1˜3). In this research, we employed a plasma beam system to ArF PR to expose active species, i.e. ions and radicals, produced in the inductively coupled plasma of fluorocarbon gases. The ion species are accelerated to specific bombardment energy. The plasma beam chamber is connected to analysis chamber of x-ray photoelectron spectroscopy, and the modified surface layer of ArF PR by the plasma beam produced was analyzed with in-situ analysis. From the XPS results, we found the modified layer after CF4 plasma beam exposure was fluorinated more than that of C4F8.

Takeuchi, Takuya; Amasaki, Shinpei; Takeda, Keigo; Ishikawa, Kenji; Kondo, Hiroki; Sekine, Makoto; Hori, Masaru

2011-11-01

69

Etching of low-k materials in high density fluorocarbon plasma  

NASA Astrophysics Data System (ADS)

Low dielectric constant materials (low-k) are used as interlevel dielectrics in integrated circuits. This paper concerns the etching process of these materials in high density plasma with the aim to provide some insights concerning the etch mechanisms. Materials studied are methylsilsesquioxane (MSQ) polymers, either dense (SiOC) or containing 40% of porosity (porous SiOC). Amorphous hydrogenated silicon carbide (SiC) material, used as hard mask and/or etch stop layer, is also investigated. Etch is performed in an inductively coupled reactor using fluorocarbon gases, which have proven to be very successful in the etch of conventional SiO{2}. First, etching with hexafluoroethane (C{2}F{6}) is performed. Although etch rates are high, etch selectivities with respect to SiC are weak. So, oxygen, argon, and hydrogen are added to C{2}F{6} with the aim of improving selectivities. The best selectivity is obtained for the C{2}F{6}/H{2} (10% 90%) mixture. To understand etch rate and selectivity variations, plasma analyses by optical emission spectroscopy are correlated to surface analysis using X-Ray Photoelectron Spectroscopy (XPS). In general, atomic fluorine concentration in the plasma explains the etch rate, while the presence of a fluorocarbon layer on the surface is well correlated to the selectivity. To ensure that the etch process does not affect materials properties, and particularly their dielectric constant, bulk analysis by Fourier Transformed Infra-Red spectroscopy and images by Scanning Electron Microscopy have also been carried out.

Eon, D.; Raballand, V.; Cartry, G.; Peignon-Fernandez, M.-C.; Cardinaud, Ch.

2004-12-01

70

Study of fluorocarbon plasma in 60 and 100 MHz capacitively coupled discharges using mass spectrometry  

SciTech Connect

The signals of positive ions and radicals formed in the fluorocarbon plasma of the capacitively coupled plasma reactor were measured using a quadrupole mass spectrometry and optical emission actinometry. The plasma was produced at 60 and 100 MHz frequencies for the same reactor configuration and gas mixtures. Experiments were performed at 25 mTorr with a SiO{sub 2} wafer on the grounded electrode. Mass spectra of ions were measured in C{sub 4}F{sub 8}/O{sub 2}/Ar and C{sub 4}F{sub 6}/O{sub 2}/Ar gas mixtures at 500-1500 W generator powers. For 60 and 100 MHz discharges production of fluorocarbon ions and radicals is discussed. It was found that the production of heavy species increases with frequency. The high mass signals such as C{sub 3}F{sub 3}{sup +}, C{sub 2}F{sub 4}{sup +}, C{sub 2}F{sub 5}{sup +}, C{sub 3}F{sub 5}{sup +}, C{sub 4}F{sub 7}{sup +} decrease when CHF{sub 3} is added to the gas mixture. However, the signals of CF{sub x}{sup +} (x=1,2,3) do not change significantly. These results are compared to the results of polymer film deposition on the wafer. It was suggested to control the polymerization film formation by adding small amount of CHF{sub 3} to the process mixture.

Ushakov, Andrey; Volynets, Vladimir; Jeong, Sangmin; Sung, Dougyong; Ihm, Yongho; Woo, Jehun; Han, Moonhyeong [Mechatronics and Manufacturing Technology Center, Samsung Electronics Co. Ltd., 416 Maetan-3 dong, Yeongtong-Gu, Suwon, Gyeonggi-Do 443-742 (Korea, Republic of)

2008-09-15

71

Fluorocarbon and hydrocarbon N-heterocyclic (c5-c7) imidazole-based liquid crystals.  

PubMed

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

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

2014-12-01

72

Solid particle production in fluorocarbon plasmas II: Gas phase reactions for polymerization  

NASA Astrophysics Data System (ADS)

Solid particles were observed in fluorocarbon (C4F8) plasmas applied to semiconductor plasma processing. In order to elucidate gas-phase reactions for particle formation, Fourier transform infrared (FTIR) spectroscopy was employed. The method showed that stable molecules (CF4, C2F6, and C2F4) were produced in the plasmas. Several absorption peaks found in a spectrum from a surface polymer were observed in the gas phase. The peaks were regarded to be from plasma-polymerized molecules in the plasmas. In particular, the absorption signals from species of -CF=CF- and -CF=CF2, which were produced from C2F4 molecules, were extinguished with the particle formation. Furthermore, densities of fluorocarbon radicals CFx (x=1,2,3) were measured in CHF3 and C2F6 plasmas as well as in C4F8 plasmas with infrared laser absorption spectroscopy. The pressure dependence of the densities drastically changed with the presence of the particles. This was induced by sticking of the radicals onto gas-phase polymers including the particles. As the results obtained in the infrared spectroscopic methods, it was found that not these radicals but the C2F4 molecule as a reactive product played an important role in the formation of the particles.

Takahashi, Kazuo; Tachibana, Kunihide

2002-03-01

73

Fluorocarbon impurities in KrF lasers Helen H. Hwang, Kristopher James, Roger Hui, and Mark J. KushneP)  

E-print Network

Fluorocarbon impurities in KrF lasers Helen H. Hwang, Kristopher James, Roger Hui, and Mark J impurities' are known to have deleterious effects on the operation of excimer lasers; however, the sensitivity limits are poorly known. Absorption at 248.9 nm in an e-beam-pumped KrF laser has been attributed

Kushner, Mark

74

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

75

Assessment of effects on vegetation of degradation products from alternative fluorocarbons  

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

76

Effect of a semifluorinated copolymer on the phase separation of a fluorocarbon/hydrocarbon mixture  

SciTech Connect

Fluorocarbons (C{sub n}F{sub 2n+2}) and hydrocarbons (C{sub n}H{sub 2n+2}) are mutually immiscible at room temperature, while they form clear and homogeneous mixtures at high temperatures. The phase separation curves of these systems show upper critical solution temperatures (UCST), which depend on the chemical formulas of the two liquids. In this paper we report the first observation of the mixing between perfluoroctane (PFO) and isooctane (FOCT) at low temperature upon addition of a semifluorinated diblock copolymer (F{sub 8}H{sub 16}). Further cooling results in phase separation or formation of solid gels, depending on the amount of copolymer added to the mixture. Phase diagrams, light-scattering, birefringence, and small-angle X-ray-scattering measurements indicate the presence of microdomains in the gel and in the liquid phase, depending on the temperature and on the copolymer volume fraction. 31 refs., 11 figs., 2 tabs.

Nostro, P.L. [Univ. of South Florida, Tampa, FL (United States); Ku, C.Y.; Chen, S.H. [Massachusetts Inst. of Technology, Cambridge, MA (United States); Lin, J.S. [Oak Ridge National Lab., TN (United States)

1995-07-06

77

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

NASA Astrophysics Data System (ADS)

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

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

2008-02-01

78

Cosurfactant effect of a semifluorinated alkane at a fluorocarbon/water interface: impact on the stabilization of fluorocarbon-in-water emulsions.  

PubMed

Previous work has demonstrated that semifluorinated alkanes CnF2n+1CmH2m+1 (FnHm diblocks), when used in conjunction with phospholipids, strongly stabilize fluorocarbon (FC)-in-water emulsions destined to be used as oxygen carriers. Although the presence of FnHm diblocks in the emulsion's interfacial phospholipid film was suggested to account for the observed stabilization, no direct proof of the diblock's location has been provided so far. We now report definite experimental evidence of the diblock's presence at the interfacial film, both on a macroscopic level by investigating the FC/water interface using the pendant drop method and directly on emulsions by monitoring their stability for various phospholipid chain lengths. We first establish that F8H16 has a strong cosurfactant effect with phospholipids [dimyristoylphosphatidylcholine (DMPC), dilaurylphosphatidylcholine (DLPC), dioctanoylphosphatidylcholine (PCL8)] at a perfluorooctyl bromide (PFOB)/water interface, as evidenced by a dramatic F8H16-concentration-dependent decrease of the interfacial tension. Where FC emulsions are concerned, we show that the stabilization effect, which consists of a decrease of the rate of molecular diffusion of the FC, depends strongly on the length of the phospholipid's fatty chain as compared to the length of the hydrocarbon segment, Hm, of the diblock. Stabilization is maximized when the Hm length is similar to that of the phospholipid's fatty chains. A strong mismatch between Hm and the phospholipid chain length can actually destabilize the emulsion. A different destabilization mechanism is then at work: coalescence. The presence of F8H16 at the interfacial film is further supported by the fact that perfluorodecyl bromide, a heavy analogue of PFOB that stabilizes PFOB emulsions by lowering the solubility and diffusibility of the emulsion's dispersed FC phase, exercises its stabilizing effect similarly for all the phospholipids investigated. PMID:15969380

Bertilla, Sabina Marie; Thomas, Jean-Louis; Marie, Pascal; Krafft, Marie Pierre

2004-05-11

79

Polymer radiation curing: Epoxies, phenolics, fluorocarbons, and silicones. (Latest citations from the NTIS data base). Published Search  

SciTech Connect

The bibliography contains citations concerning the processes and effects of radiation curing on epoxy resins, phenolics, fluorocarbons, and silicones. Gamma, ultraviolet, and infrared radiation are emphasized; however, polymer crosslinking by such electromagnetic wave radiation as microwave, laser, vacuum irradiation, and ionization is included. The citations also discuss the influence of radiation induced polymer curing on mechanical, electrical, and chemical properties of the polymers. (Contains a minimum of 235 citations and includes a subject term index and title list.)

Not Available

1992-09-01

80

3D feature profile simulation based on realistic surface kinetic studies of silicon dioxide etch process in fluorocarbon plasmas  

NASA Astrophysics Data System (ADS)

Low pressure fluorocarbon plasmas are commonly used in microelectronics fabrication of plasma etching of dielectric materials. Recently, one of the critical issues in the etching processes of the nanoscale devices is to achieve ultrahigh deep contact hole without anomalous behaviors such as sidewall bowing and twisting profile. To achieve this goal, the fluorocarbon gases have been used to optimize the reactant fluxes and obtain the ideal etch profile. However, the semiconductor industries still suffer from the absence of the robust and predictable modeling tools due to the inherent complex plasma chemistry. As an effort to address this issue, we have developed a 3D topography simulator using the level set algorithm based on new memory saving technique, which is suitable in the contact hole etching. For this feature profile simulation, we performed a fluorocarbon plasma-surface kinetic modeling based on our experimental data, a polymer layer based this model was proposed as considering material balance of deposition and etching through steady-state FC layer. Finally, the modeling results showed good agreements with experimental data and could be used successfully for 3D etch profile simulations with consideration of polymer layer.

Chang, Won-Seok; Yu, Dong-Hun; Cho, Deog-Gyun; Yook, Yeong-Geun; Chun, Poo-Reum; Lee, Se-A.; Kwon, Deuk-Chul; Song, Mi-Young; Yoon, Jung-Sik; Im, Yeon-Ho

2012-10-01

81

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

PubMed Central

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

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

2013-01-01

82

Exchange transfusion with fluorocarbon for studying synaptically evoked optical signal in rat cortex.  

PubMed

Optical imaging of intrinsic signal is a powerful technique for studying the functional organization of the brain [T. Bonhoeffer, D. S. Kim, D. Malonek, D. Shoham, A. Grinvald, Optical imaging of the layout of functional domains in area 17 and across the area 17/18 border in cat visual cortex, Eur. J. Neurosci. 7 (1995) 1973-1988; M. Hubener, D. Shoham, A. Grinvald, T. Bonhoeffer, Spatial relationships among three columnar systems in cat area 17, J. Neurosci. 17 (1997) 9270-9284; D. Malonek, A. Grinvald, Interactions between electrical activity and cortical microcirculation revealed by imaging spectroscopy: implications for functional brain mapping, Science 272 (1996) 551-554; A. Shmuel, A. Grinvald, Functional organization for direction of motion and its relationship to orientation maps in cat area 18, J. Neurosci. 16 (1996) 6945-6964] [1] [10] [14] [22]. Three components of intrinsic optical signal can be distinguished. Two of these components can be attributed either to changes in blood volume or to changes in oxygen consumption [R.D. Frostig, E.E. Lieke, D.Y. Ts'o, A. Grinvald, Cortical functional architecture and local coupling between neuronal activity and the microcirculation revealed by in vivo high resolution optical imaging of intrinsic signals, Proc. Natl. Acad. Sci. U. S. A. 87 (1990) 6082-6086] [7]. The origin of the third component is not yet clear but the component seems to be based on scattered light [H.U. Dodt, G. D'Arcangelo, E. Pestel, W. Zieglgansberger, The spread of excitation in neocortical columns visualized with infrared-dark field videomicroscopy, NeuroReport 7 (1996) 1553-1558; K. Holthoff, O.W. Witte, Intrinsic optical signals in rat neocortical slices measured with near-infrared dark-field microscopy reveal changes in extracellular space, J. Neurosci. 16 (1996) 2740-2749; B.A. MacVicar, D. Hochman, Imaging of synaptically evoked intrinsic optical signals in hippocampal slices, J. Neurosci. 11 (1991) 1458-1469; L. Trachsel, H.U. Dodt, W. Zieglgansberger, The intrinsic optical signal evoked by chiasm stimulation in the rat suprachiasmatic nuclei exhibits GABAergic day-night variation, Eur. J. Neurosci. 8 (1996) 319-328] [3] [9] [13] [24]. A spectral fitting method with three components is used for the analysis of intrinsic optical signal [M. Nemoto, Y. Nomura, C. Sato, M. Tamura, K. Houkin, I. Koyanagi, H. Abe, Analysis of optical signals evoked by peripheral nerve stimulation in rat somatosensory cortex: dynamic changes in hemoglobin concentration and oxygenation, J. Cereb. Blood Flow Metab. 19 (1999) 246-259] [17]. In order to validate the analysis, we need the knowledge on contribution of signal resulted from hemoglobin to total intrinsic optical signal. The exchange transfusion with fluorocarbon has the advantage that can change the spectral contribution of hemoglobin [M. Ferrari, M.A. Williams, D.A. Wilson, N.V. Thakor, R.J. Traystman, D.F. Hanley, Cat brain cytochrome-c oxidase redox changes induced by hypoxia after blood-fluorocarbon exchange transfusion, Am. J. Physiol. 269 (1995) H417-H424; A.L. Sylvia, C.A. Piantadosi, O(2) dependence of in vivo brain cytochrome redox responses and energy metabolism in bloodless rats, J. Cereb. Blood Flow Metab. 8 (1988) 163-172] [6] [23]. Here we describe a new method of the reduction of hemoglobin signal from somatosensory evoked optical intrinsic signal in rat cortex by the combination of exchange transfusion with fluorocarbon and imaging system of thinned skull cranial window. The method allows for the study of the synaptically evoked changes in light scattering as well as fluorescence of calcium indicator or voltage-sensitive dye without absorption of hemoglobin. PMID:10719260

Nomura, Y; Fujii, F; Sato, C; Nemoto, M; Tamura, M

2000-02-01

83

Beam Simulation Studies of Plasma-Surface Interactions in Fluorocarbon Etching of Silicon and Silicon Dioxide  

NASA Astrophysics Data System (ADS)

A molecular beam apparatus has been constructed which allows the synthesis of dominant species fluxes to a wafer surface during fluorocarbon plasma etching. These species include atomic F as the primary etchant, CF _2 as a potential polymer forming precursor, and Ar^{+} or CF _{rm x}^{+} type ions. Ionic and neutral fluxes employed are within an order of magnitude of those typical of fluorocarbon plasmas and are well characterized through the use of in -situ probes. Etching yields and product distributions have been measured through the use of in-situ laser interferometry and line-of-sight mass spectrometry. XPS studies of etched surfaces were performed to assess surface chemical bonding states and average surface stoichiometry. A useful design guide was developed which allows optimal design of straight -tube molecular beam dosers in the collisionally-opaque regime. Ion-enhanced surface reaction kinetics have been studied as a function of the independently variable fluxes of free radicals and ions, as well as ion energy and substrate temperature. We have investigated the role of Ar ^{+} ions in enhancing the chemistries of F and CF_2 separately, and in combination on undoped silicon and silicon dioxide surfaces. We have employed both reactive and inert ions in the energy range most relevant to plasma etching processes, 20-500 eV, through the use of Kaufman and ECR type ion sources. The effect of increasing ion energy on the etching of fluorine saturated silicon and silicon dioxide surfaces was quantified through extensions of available low energy physical sputtering theory. Simple "site"-occupation models were developed for the quantification of the ion-enhanced fluorine etching kinetics in these systems. These models are suitable for use in topography evolution simulators (e.g. SAMPLE) for the predictive modeling of profile evolution in non-depositing fluorine-based plasmas such as NF_3 and SF_6. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617 -253-5668; Fax 617-253-1690.) (Abstract shortened with permission of school.).

Gray, David C.

1992-01-01

84

Effect of Molecular Orientation on Monolayer and Multilayer Formations of Fluorocarbon Alcohol and Fluorocarbon-?,?-diol Mixture at the Hexane/water Interface.  

PubMed

The effect of molecular orientation on the miscibility and structure of the adsorbed film of the 1H,1H,10H,10H-perfluorodecane-1,10-diol (FC10diol)-1H,1H,2H,2H-perfluorodecanol (FC10OH) mixture at the hexane/water interface were examined by interfacial tension and X-ray reflectivity measurements. The interfacial tension and X-ray reflectivity at the hexane solution/water interface were measured as a function of total molality m and composition of FC10OH in the mixture X2 under atmospheric pressure at 298.15 K. The interfacial pressure vs mean area per molecule curves showed that two kinds of condensed monolayers (C1 and C2) and multilayer (M) states appeared depending on m and X2. In the pure component systems, it was found that FC10OH forms condensed monolayer in which the molecules orient almost normally to the interface, and FC10diol orients parallel and is densely packed in the condensed monolayer and then piles spontaneously to form multilayer. In the mixed system, the phase diagram of adsorption indicated that FC10OH molecules are richer in C2 than in C1 state. The X-ray reflectivity measurements manifest that the condensed monolayer below X2 = 0.985 is heterogeneous in which the normal- and parallel-oriented domains coexist at the interface (C1 state), and that above X2 = 0.985 seems to be homogeneous with normal molecular orientation (C2 state). The structure of M state depends on those of condensed monolayers, on which the molecules pile spontaneously. The heterogeneous structure in C1 state is compared to that previously observed in the mixed system of FC10diol-FC12OH (1H,1H,2H,2H-perfluorododecanol), where FC12OH has longer fluorocarbon chain length than FC10OH and is discussed in terms of domain line tension. PMID:25280128

Fukuhara, Ryushi; Tanida, Hajime; Nitta, Kiyofumi; Ina, Toshiaki; Uruga, Tomoya; Matsubara, Hiroki; Aratono, Makoto; Takiue, Takanori

2014-10-30

85

Fluorocarbon and PTFE thermodegradation and contamination modeling in a space habitat  

NASA Astrophysics Data System (ADS)

The products of thermodegradation of fluorocarbon polymers (found in electrical insulation) will be toxic to space habitat crews, and the monitoring and detection of such contaminants are important to space environmental health. Experiments are therefore being performed on the thermodegradation of a liquid perfluorokane mixture similar in structure to polytetrafluoroethylene (PTFE - Teflon), in atmospheres of varying oxygen concentration. PTFE is a common material used on space vehicles for insulation of wires. When PTFE is thermally degraded, such as from the overheating of a wire and subsequent smoldering of the insulation, it may produce toxic compounds ranging from carbonyl fluoride and hydrogen fluoride through perfluorinated aromatic compounds to ultrafine particles. The liquid perffluoroalkane (PFA) mixture is vaporized in the presence of helium, which is used as a carrier gas in this experiment and is acting in place of nitrogen as the non-reactive portion of the atmosphere. The helium and perfluoroalkane vapor can then be mixed with oxygen to yield atmospheres of known concentrations. The mixture is fed into a tube reactor furnace where it is thermally degraded. The resulting thermodegradation products are analyzed by combined gas chromatography/mass spectrometry (GC/MS) for composition. This analysis allows the characterization of the reaction products for simulation models and monitoring and detection systems in space habitats.

Smith, Gerald J.; Todd, Paul W.; Barkley, Robert M.; McKinnon, J. Thomas

86

Surface kinetics and plasma equipment model for Si etching by fluorocarbon plasmas  

NASA Astrophysics Data System (ADS)

Plasma-surface interactions during plasma etching are important in that, in addition to determining the rate and quality of the etch, they can also influence the properties of the bulk plasma. To address this coupling of bulk and surface processes the surface kinetics model (SKM) was developed as a module in the two-dimensional hybrid plasma equipment model (HPEM) with the goal of combining plasma chemistry and surface chemistry in a self-consistent fashion. The SKM obtains reactive fluxes to the surface from the HPEM, and generates the surface species coverages and the returning fluxes to the plasma by implementing a user defined surface reaction mechanism. Although the SKM is basically a surface-site-balance model, extensions to those algorithms have been made to include an overlying passivation layer through which reactants and products diffuse. Etching of Si in an inductively coupled plasma sustained in Ar/C2F6 was investigated using the SKM. Results from parametric studies are used to demonstrate the sensitivity of etching rates and polymer thickness to the sticking coefficient of fluorocarbon radicals on the reactor walls, polymer erosion rates and F atom diffusion through the polymer layer.

Zhang, Da; Kushner, Mark J.

2000-02-01

87

Fluidization of a Dipalmitoyl Phosphatidylcholine Monolayer by Fluorocarbon Gases: Potential Use in Lung Surfactant Therapy  

PubMed Central

Fluorocarbon gases (gFCs) were found to inhibit the liquid-expanded (LE)/liquid-condensed (LC) phase transition of dipalmitoyl phosphatidylcholine (DPPC) Langmuir monolayers. The formation of domains of an LC phase, which typically occurs in the LE/LC coexistence region upon compression of DPPC, is prevented when the atmosphere above the DPPC monolayer is saturated with a gFC. When contacted with gFC, the DPPC monolayer remains in the LE phase for surface pressures lower than 38 mN m?1, as assessed by compression isotherms and fluorescence microscopy (FM). Moreover, gFCs can induce the dissolution of preexisting LC phase domains and facilitate the respreading of the DPPC molecules on the water surface, as shown by FM and grazing incidence x-ray diffraction. gFCs have thus a highly effective fluidizing effect on the DPPC monolayer. This gFC-induced fluidizing effect was compared with the fluidizing effect brought about by a mixture of unsaturated lipids and proteins, namely the two commercially available lung surfactant substitutes, Curosurf and Survanta, which are derived from porcine and bovine lung extracts, respectively. The candidate FCs were chosen among those already investigated for biomedical applications, and in particular for intravascular oxygen transport, i.e., perfluorooctyl bromide, perfluorooctylethane, bis(perfluorobutyl)ethene, perfluorodecalin, and perfluorooctane. The fluidizing effect is most effective with the linear FCs. This study suggests that FCs, whose biocompatibility is well documented, may be useful in lung surfactant substitute compositions. PMID:16500985

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

2006-01-01

88

Fluidization of a dipalmitoyl phosphatidylcholine monolayer by fluorocarbon gases: potential use in lung surfactant therapy.  

PubMed

Fluorocarbon gases (gFCs) were found to inhibit the liquid-expanded (LE)/liquid-condensed (LC) phase transition of dipalmitoyl phosphatidylcholine (DPPC) Langmuir monolayers. The formation of domains of an LC phase, which typically occurs in the LE/LC coexistence region upon compression of DPPC, is prevented when the atmosphere above the DPPC monolayer is saturated with a gFC. When contacted with gFC, the DPPC monolayer remains in the LE phase for surface pressures lower than 38 mN m(-1), as assessed by compression isotherms and fluorescence microscopy (FM). Moreover, gFCs can induce the dissolution of preexisting LC phase domains and facilitate the respreading of the DPPC molecules on the water surface, as shown by FM and grazing incidence x-ray diffraction. gFCs have thus a highly effective fluidizing effect on the DPPC monolayer. This gFC-induced fluidizing effect was compared with the fluidizing effect brought about by a mixture of unsaturated lipids and proteins, namely the two commercially available lung surfactant substitutes, Curosurf and Survanta, which are derived from porcine and bovine lung extracts, respectively. The candidate FCs were chosen among those already investigated for biomedical applications, and in particular for intravascular oxygen transport, i.e., perfluorooctyl bromide, perfluorooctylethane, bis(perfluorobutyl)ethene, perfluorodecalin, and perfluorooctane. The fluidizing effect is most effective with the linear FCs. This study suggests that FCs, whose biocompatibility is well documented, may be useful in lung surfactant substitute compositions. PMID:16500985

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

2006-05-01

89

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

90

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

PubMed

Metal-organic and covalent organic frameworks are porous materials characterized by outstanding thermal stability, high porosities and modular synthesis. Their repeating structures offer a great degree of control over pore sizes, dimensions and surface properties. Similarly precise engineering at the nanoscale is difficult to achieve with discrete molecules, since they rarely crystallize as porous structures. Here we report a small organic molecule that organizes into a noncovalent organic framework with large empty pores. This structure is held together by a combination of [N-H···N] hydrogen bonds between the terminal pyrazole rings and [?···?] stacking between the electron-rich pyrazoles and electron-poor tetrafluorobenzenes. Such a synergistic arrangement makes this structure stable to at least 250?°C and porous, with an accessible surface area of 1,159?m(2)?g(-1). Crystals of this framework adsorb hydrocarbons, CFCs and fluorocarbons-the latter two being ozone-depleting substances and potent greenhouse species-with weight capacities of up to 75%. PMID:25307413

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

2014-01-01

91

Feature Profile Evolution of SiO2 Trenches In Fluorocarbon Plasmas  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

92

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

93

Gain and loss mechanisms for neutral species in low pressure fluorocarbon plasmas by infrared spectroscopy  

SciTech Connect

This article examines the chemical reaction pathways of stable neutral species in fluorocarbon plasmas. Octafluorocyclobutane (c-C{sub 4}F{sub 8}) inductively coupled plasma discharges were found to primarily produce stable and metastable products downstream from the discharge, including c-C{sub 4}F{sub 8}, C{sub 2}F{sub 4}, C{sub 2}F{sub 6}, CF{sub 4}, C{sub 3}F{sub 8}, C{sub 4}F{sub 10}, C{sub 3}F{sub 6}, and CF{sub 2}. A novel analysis technique allows the estimation of gain and loss rates for neutral species in the steady state as functions of residence time, pressure, and discharge power. The gain and loss rates show that CF{sub 4}, C{sub 2}F{sub 6}, C{sub 3}F{sub 8}, and C{sub 4}F{sub 10} share related gain mechanisms, speculated to occur at the surface. Further analysis confirms that CF{sub 2} is predominantly produced at the chamber walls through electron impact dissociation of C{sub 2}F{sub 4} and lost through gas-phase addition reactions to form C{sub 2}F{sub 4}. Additionally, time-resolved FTIR spectra provide a second-order rate coefficient of 1.8 Multiplication-Sign 10{sup -14} cm{sup 3}/s for the gas-phase addition of CF{sub 2} to form C{sub 2}F{sub 4}. Finally, C{sub 2}F{sub 4,} which is much more abundant than CF{sub 2} in the discharge, is shown to be dominantly produced through electron impact dissociation of c-C{sub 4}F{sub 8} and lost through either surface or gas-phase addition reactions.

Nelson, Caleb T.; Overzet, Lawrence J.; Goeckner, Matthew J. [Department of Electrical Engineering, University of Texas at Dallas, P.O. Box 830688, Richardson, Texas 75083 (United States)

2012-09-15

94

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

SciTech Connect

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

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

2005-06-15

95

New approach to a collodion membrane composite via fluorocarbon polymer (Nafion) blending in terms of a diffusion coefficient of redox substances and transport properties  

Microsoft Academic Search

Nafion (fluorocarbon polymer) and collodion blended with Nafion in the ratio of CN5:5 composite solutions were used to produce thin membrane films on Au electrodes. It was found that the transport properties of water and KCl, such as the filtration coefficient, Lp, reflection coefficient, ? and salt permeation, ?, across the two composite collodion (C) and Nafion (N) membranes depended

Akira Yamauchi; A. Mounir El Sayed

2006-01-01

96

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

97

Computer modeling of low-pressure fluorocarbon-based discharges for etching purposes  

NASA Astrophysics Data System (ADS)

This work has been focused on developing a 1d3v particle-in-cell/Monte Carlo collision model with minimum approximations and on its application to study symmetric and asymmetric fluorocarbon-based discharges sustained in single- and dual-frequency etching reactors. The discharge characteristics in Ar/CF4 discharges have been studied and the transition from electropositive to electronegative behavior has been clarified. The calculated electronegativities in an Ar/CF4 discharge are in good agreement with the experimental data. The novelty of the present work is the development of a numerical model for a complex gas mixture of Ar, CF4, and N2 used for etching in an industrial dual-frequency reactor. In contrast with the single-HF reactor, where the negative ions are confined in the plasma, in the dual-frequency regime the negative ions can respond to the applied LF electric field and it is found that energetic negative F- ions reach the electrodes, consequently they can influence the etching process. It has been observed that the ion-energy distribution is significantly wider in the dual-frequency in comparison with the conventional reactors. An analytical model for the ion energy width in a dual-frequency reactor has been developed. Good quantitative agreement is obtained between the theoretical and simulation results. A detailed numerical investigation has been made to study the influence of the reactor parameters on the plasma characteristics in Ar/CF4/N 2 plasmas in a dual-frequency reactor. It is observed that the decoupling of the two sources is possible with increase of the applied HF to values of 60 MHz and higher, and it is not defined by the frequency ratio. The asymmetry determines the formation of a self-bias voltage at the powered electrode. A detailed investigation has been made to study the influence of the electrode area ratio and both power source parameters on the plasma characteristics in an asymmetric dual-frequency reactor. In conclusion, the present investigation has covered the influence of a wide range of different reactor parameters of single- and dual-frequency reactors on the plasma behavior so that they can be adjusted to obtain desirable plasma characteristics. Therefore, this study can be useful in improving control over the etching process.

Georgieva, Violeta

98

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

99

The detrimental effect of serum albumin on the re-spreading of a dipalmitoyl phosphatidylcholine Langmuir monolayer is counteracted by a fluorocarbon gas  

Microsoft Academic Search

We have recently reported that fluorocarbon gases exhibit an effective fluidizing effect on Langmuir monolayers of dipalmitoyl phosphatidylcholine (DPPC), preventing them from crystallizing up to surface pressures of ?40 mN m?1, i.e. well above the DPPC's equilibrium surface pressure. We now report that gaseous perfluorooctyl bromide (gPFOB) promotes the re-spreading of DPPC Langmuir monolayers compressed on a bovine serum albumin (BSA)-containing

Frédéric Gerber; Marie Pierre Krafft; Thierry F. Vandamme

2007-01-01

100

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

101

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

SciTech Connect

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

Sant, S. P.; Nelson, C. T.; Overzet, L. J.; Goeckner, M. J. [Electrical Engineering, University of Texas at Dallas, 800 W Campbell, Richardson, Texas 75080 (United States)

2009-07-15

102

Integrated feature scale modeling of plasma processing of porous and solid SiO2. I. Fluorocarbon etching  

NASA Astrophysics Data System (ADS)

Increases in RC delay times in interconnect wiring for microelectronics as feature sizes decrease have motivated investigations into the use of low-dielectric constant insulators, and in particular, porous silicon-dioxide (PS). Profile evolution and maintenance of critical dimensions during plasma etching of PS are problematic due to the exposure of open pores. To investigate these issues, reaction mechanisms for fluorocarbon plasma etching of SiO2 in C2F6, CHF3, and C4F8 chemistries have been developed and incorporated into the Monte Carlo Feature Profile Model which was modified to address these two-phase systems. The reaction mechanism was validated by comparison to experiments by others for etching of PS and solid SiO2 (SS). We found that the etch rates for PS are generally higher than that of SS due to the inherently lower mass fraction. Mass corrected etch rates of PS can be larger or smaller than those for SS depending on the degree of pore filling by polymer and the degree of ion activated chemical sputtering. Pore filling is particularly important for PS having open networks with large pores and high porosities. We found little dependence of the taper of high aspect ratio profiles on the average pore radius and porosity. However, the profile changes from tapered to bowed as the interconnectivity of the porous network increases. Scaling laws for profile shapes are otherwise similar for both SS and PS. .

Sankaran, Arvind; Kushner, Mark J.

2004-07-01

103

Neutralization of methyl cation via chemical reactions in low-energy ion-surface collisions with fluorocarbon and hydrocarbon self-assembled monolayer films  

Microsoft Academic Search

Low-energy ion-surface collisions of methyl cation at hydrocarbon and fluorocarbon self-assembled monolayer (SAM) surfaces\\u000a produce extensive neutralization of CH3+. These experimental observations are reported together with the results obtained for ion-surface collisions with the molecular\\u000a ions of benzene, styrene, 3-fluorobenzonitrile, 1,3,5-triazine, and ammonia on the same surfaces. For comparison, low-energy\\u000a gas-phase collisions of CD3+ and 3-fluorobenzonitrile molecular ions with neutral

Á. rpád Somogyi; Darrin L. Smith; Vicki H. Wysocki; Ramon Colorado; T. Randall Lee

2002-01-01

104

Dissociative electron attachment to the highly reactive difluoromethylene molecule-importance of CF2 for negative ion formation in fluorocarbon plasmas  

NASA Astrophysics Data System (ADS)

Dissociative electron attachment to the highly reactive difluoromethylene molecule, CF2, produced in a C3F6/He microwave plasma and stepwise via the fast atom reaction CF3I+H?CF3+HI and CF3+H?CF2+HF, has been investigated. The upper limit for the cross section of formation of F- via dissociative electron attachment to CF2 is estimated to be 5×10-4 Å2. This value is four orders of magnitude smaller than the cross section previously predicted from scattering calculations. It is concluded that difluoromethylene plays a negligible role in negative ion formation in fluorocarbon plasmas.

Graupner, K.; Field, T. A.; Mayhew, C. A.

2010-08-01

105

Biophysical investigation of the interfacial properties of cationic fluorocarbon/hydrocarbon hybrid surfactant: mimicking the lung surfactant protein C.  

PubMed

The interfacial behavior of the newly designed Fluorocarbon Hydrocarbon Cationic Lipid (FHCL or CH(3)(CH(2))(17)N(+)(C(2)H(5))(2)(CH(2))(3)(CF(2))(7)CF(3)I(-)) and its mixtures with a phospholipid (DPPC, Dipalmitoylphosphatidylcholine) at different mole fractions were investigated. This new molecule was synthesized to mimic the selected properties of lung surfactant, which is a natural lipid-protein mixture which is known to play important roles in the process of respiration, by considering the structure/function relation of lung surfactant protein (SP-C). Each segment in the molecular structure was selected to affect the molecular level interaction at the interface whereas the keeping the overall structure as simple as possible. The surface pressure area isotherms obtained for the mixtures of DPPC/FHCL indicated that there was repulsive interaction between DPPC and FHCL molecules. Due to the molecular level interaction, specifically at mole fraction 0.3, the isotherm obtained from that mixture resembled the isotherm obtained from the DPPC monolayer in the presence of SP-C. High elasticity of the interface was one of the important parameters for the respiration process, therefore, shear and dilatational elasticities of two-component systems were determined and they were found to be similar to the case where SP-C protein is present. Fluorescence microscopy images were taken in order to investigate the monolayer in details. The FHCL was able to fluidize the DPPC monolayer even at high surface pressures effectively. In addition, the cyclic compression-expansion isotherms were obtained to understand the spreading and re-spreading ability of the pure FHCL and the mixed DPPC/FHCL monolayers. At a specific mole fraction, X(FHCL)=0.3, the mixture exhibited good hysteresis in area, compressibility, recruitment index and re-spreading ability at the interface. All these results point out that FHCL can fulfill the selected features of the lung surfactant that are attributed to the presence of SP-C protein when mixed with DPPC, even if the molecular structure of the FHCL is quite simple. PMID:21555131

Aydogan, Nihal; Uslu, Burcin; Tanaci, Hacer

2011-08-01

106

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

SciTech Connect

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

Kang, S.-K. [SKKU Advanced Institute of Nanotechnology, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746 (Korea, Republic of); Oh, J. S.; Park, B. J.; Kim, S. W.; Lim, J. T. [Department of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746 (Korea, Republic of); Yeom, G. Y. [SKKU Advanced Institute of Nanotechnology, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746 (Korea, Republic of); Department of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746 (Korea, Republic of); Kang, C. J.; Min, G. J. [Memory Division, Samsung Electronics Co. Ltd., Yongin City, Gyeonggi-do 440-746 (Korea, Republic of)

2008-07-28

107

The detrimental effect of serum albumin on the re-spreading of a dipalmitoyl phosphatidylcholine Langmuir monolayer is counteracted by a fluorocarbon gas.  

PubMed

We have recently reported that fluorocarbon gases exhibit an effective fluidizing effect on Langmuir monolayers of dipalmitoyl phosphatidylcholine (DPPC), preventing them from crystallizing up to surface pressures of approximately 40 mN m(-1), i.e. well above the DPPC's equilibrium surface pressure. We now report that gaseous perfluorooctyl bromide (gPFOB) promotes the re-spreading of DPPC Langmuir monolayers compressed on a bovine serum albumin (BSA)-containing sub-phase. The latter protein is known to maintain a concentration-dependent surface pressure that can exceed the re-spreading pressure of collapsed monolayers. This phenomenon was proposed to be responsible for lung surfactant inactivation. Compression/expansion isotherms and fluorescence microscopy experiments were carried out to assess the monolayers' physical state. We have found that, during expansion under gPFOB-containing air, the surface pressure of a DPPC monolayer on a BSA-containing sub-phase decreased to much lower values than when the DPPC monolayer was expanded in the presence of BSA under air ( approximately 0 mN m(-1) vs. approximately 7.5 mN m(-1) at 120 A(2), respectively). Moreover, fluorescence images showed that, during expansion, the BSA-coupled DPPC monolayers, in contact with gPFOB, remained in the liquid-expanded state for surface pressures lower than 10 mN m(-1), whereas they were in a liquid-condensed semi-crystalline state, even at large molecular areas (120 A(2)), when expanded under air. The re-incorporation of the PFOB molecules in the DPPC monolayer during expansion thus competes with the re-incorporation of BSA, thus preventing the latter from penetrating into the DPPC monolayer. We suggest that combinations of DPPC and a fluorocarbon gas may be useful in the treatment of lung conditions resulting from a deterioration of the native lung surfactant function due to plasma proteins, such as in the acute respiratory distress syndrome. PMID:17097604

Gerber, Frédéric; Krafft, Marie Pierre; Vandamme, Thierry F

2007-03-01

108

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

109

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

110

Role of chamber dimension in fluorocarbon based deposition and etching of SiO{sub 2} and its effects on gas and surface-phase chemistry  

SciTech Connect

It is well understood that chamber geometry is an influential factor governing plasma processing of materials. Simple models suggest that a large fraction of this influence is due to changes in basic plasma properties, namely, density, temperature, and potential. However, while such factors do play an important role, they only partly describe the observed differences in process results. Therefore, to better elucidate the role of chamber geometry in this work, the authors explore the influence of plasma chemistry and its symbiotic effect on plasma processing by decoupling the plasma density, temperature, and potential from the plasma-surface (wall) interactions. Specifically, a plasma system is used with which the authors can vary the chamber dimension so as to vary the plasma-surface interaction directly. By varying chamber wall diameter, 20-66 cm, and source-platen distance, 4-6 cm, the etch behavior of SiO{sub 2} (or the deposition behavior of fluorocarbon polymer) and the resulting gas-phase chemistry change significantly. Results from in situ spectroscopic ellipsometry show significant differences in etch characteristics, with etch rates as high as 350 nm/min and as low as 75 nm/min for the same self-bias voltage. Fluorocarbon deposition rates are also highly dependent on chamber dimension and vary from no net deposition to deposition rates as high as 225 nm/min. Etch yields, however, remain unaffected by the chamber size variations. From Langmuir probe measurements, it is clear that chamber geometry results in significant shifts in plasma properties such as electron and ion densities. Indeed, such measurements show that on-wafer processes are limited at least in part by ion flux for high energy reactive ion etch. However, in situ multipass Fourier transform infrared spectroscopy reveals that the line-averaged COF{sub 2}, SiF{sub 4}, CF{sub 2}, and CF{sub 3} gas-phase densities are also dependent on chamber dimension at high self-bias voltage and also correlate well to the CF{sub x} overlayer stoichiometry under deposition conditions.

Joseph, E. A.; Zhou, B.-S.; Sant, S. P.; Overzet, L. J.; Goeckner, M. J. [Plasma Science and Applications Lab, Department of Electrical Engineering, University of Texas at Dallas, M/S RL 10, 800 W. Campbell Rd., Richardson, Texas 75080 (United States)

2008-05-15

111

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

112

Fluorocarbon-bonded magnetic mesoporous microspheres for the analysis of perfluorinated compounds in human serum by high-performance liquid chromatography coupled to tandem mass spectrometry.  

PubMed

We report herein an extraction method for the analysis of perfluorinated compounds in human serum based on magnetic core-mesoporous shell microspheres with decyl-perfluorinated interior pore-walls (Fe3O4@mSiO2-F17). Thanks to the unique properties of the Fe3O4@mSiO2-F17 microspheres, macromolecules like proteins could be easily excluded from the mesoporous channels due to size exclusion effect, and perfluorinated compounds (PFCs) in protein-rich biosamples such as serum could thus be directly extracted with the fluorocarbon modified on the channel wall without any other pretreatment procedure. The PFCs adsorbed Fe3O4@mSiO2-F17 microspheres could then be simply and rapidly isolated by using a magnet, followed by being identified and quantified by LC-MS/MS (high-performance liquid chromatography coupled to tandem mass spectrometry). Five perfluorinatedcarboxylic acids (C6, C8-C11) and perfluorooctane sulfonate (PFOS) were selected as model analytes. In order to achieve the best extraction efficiency, some important factors including the amount of Fe3O4@mSiO2-F17 microspheres added, adsorption time, type of elution solvent, eluting solvent volume and elution time were investigated. The ranges of the LOD were 0.02-0.05 ng mL(-1) for the six PFCs. The recovery of the optimized method varies from 83.13% to 92.42% for human serum samples. PMID:25172813

Liu, Xiaodan; Yu, Yingjia; Li, Yan; Zhang, Haiying; Ling, Jin; Sun, Xueni; Feng, Jianan; Duan, Gengli

2014-09-24

113

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

SciTech Connect

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

Yin Yunpeng; Sawin, Herbert H. [Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2007-07-15

114

Comparison of the influence of fluorocarbon and hydrocarbon surfactants on the adsorptions of SDS, DTAB and C12E8 at the air/water interface by MD simulation  

NASA Astrophysics Data System (ADS)

Adsorptions of sodium dodecylsulfate (SDS), dodecyltrimethylammonium bromide (DTAB) and octaethylene glycol monododecyl ether (C12E8) at the air/water interface in the presence of hydrocarbon and fluorocarbon surfactants (HCEP and FCEP) were investigated by molecular dynamics (MD) simulation. With the addition of HCEP or FCEP, the monolayer is more organized than in individual surfactant systems. Extremely expanded C12E8 chain in a smaller tilt angle is discovered in C12E8/HCEP system. In SDS or DTAB systems, relatively small tilt angle of surfactants is observed in the presence of FCEP. Their analog, a silicone surfactant DSEP shows a favorable effect on interfacial properties with DTAB.

Pang, Jinyu; Xu, Guiying

2012-06-01

115

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

116

Sensitivity behavior of tin oxide based semiconducting sensor for fluorocarbons  

Microsoft Academic Search

Gas sensors based on resistance changes of selected materials have been successfully used for simple gas monitoring functions. In particular, the work on chemical sensors has gained great interest because of its application in the field of environmental monitoring devices [1] domestic safety and [2] in the food industry. One of the important areas is to develop a gas sensor

B. B. Rao; V. J. Rao

1999-01-01

117

Evaluation of unsaturated fluorocarbons for dielectric Etch applications  

E-print Network

The semiconductor industry is currently faced with the problem of the use and emissions of strong global warming compounds, known as perfluorocompounds (PFCs) for dielectric etch applications. The release of global warming ...

Chatterjee, Ritwik, 1974-

2003-01-01

118

Evaluation of a fluorocarbon plastic used in cryogenic valve seals  

NASA Technical Reports Server (NTRS)

Effects of strain rate, temperature, crystallinity, and surface finish /smoothness/ on the tensile strength of a commercial chlorotrifluorethylene plastic /CTFE/ used for lipseals in very fast-acting liquid oxygen valves.

Cierniak, R. E.; Lieb, J. H.; Mowers, R. E.

1968-01-01

119

Plaque-controlling surface modifier containing fluorocarbon chain  

Microsoft Academic Search

A silane coupling agent, CF3(CF2)9CH2CH2Si(NCO)3, prepared by hydrosilylation of trichlorosilane with CF3(CF2)9 CH?CH2 in the presence of hydrogen hexachloroplatinate(IV), followed by reaction with silver cyanate, was used for glass and bovine tooth surface modification. In ESCA of the modified glass surfaces, nitrogen atoms in the silane coupling agent bound to the surfaces were detected only at contamination levels. This ESCA

Norio Yoshino; Takashi Yamauchi; Yukishige Kondo; Tokuzo Kawase; Toshio Teranaka

1998-01-01

120

Semifluorinated Alkanes as Stabilizing Agents of Fluorocarbon Emulsions  

Microsoft Academic Search

We obtained highly stable, small-sized, and narrowly dispersed perfluorooctyl bromide (PFOB) emulsions using combinations of phospholipids and semifluorinated alkanes CnF2n+1CmH2m+1 (FnHm diblocks) as the emulsifying system. For example, after 6 months at 25°C the average droplet diameter of an emulsion stabilized by F6H10 was only ?80nm, compared to ?180 nm for the reference emulsion stabilized by phospholipids alone. In parallel,

Sabina Marie Bertilla; Pascal Marie; Marie Pierre Krafft

121

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

122

IR spectroscopy of gaseous fluorocarbon ions: The perfluoroethyl anion  

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

123

Total and ionization cross sections of electron scattering by fluorocarbons  

NASA Astrophysics Data System (ADS)

Electron impact total cross sections (50-2000 eV) and total ionization cross sections (threshold to 2000 eV) are calculated for typical plasma etching molecules CF4, C2F4, C2F6, C3F8 and CF3I and the CFx (x = 1-3) radicals. The total elastic and inelastic cross sections are determined in the spherical complex potential formalism. The sum of the two gives the total cross section and the total inelastic cross section is used to calculate the total ionization cross sections. The present total and ionization cross sections are found to be consistent with other theories and experimental measurements, where they exist. Our total cross section results for CFx (x = 1-3) radicals presented here are first estimates on these species.

Antony, B. K.; Joshipura, K. N.; Mason, N. J.

2005-02-01

124

VUV excimer laser-materials interactions with fluorocarbon polymers  

NASA Astrophysics Data System (ADS)

Particle emission from transparent wide bandgap materials at laser fluences below the threshold for optical breakdown can provide important insight on interactions at the higher fluences employed for surface modification, machining, and laser ablation deposition. We present recent studies of ion and neutral molecule emission from polytetrafluorethylene [(C2F4)N---PTFE---Teflon] and polyvinylidene fluoride [(CH2CF2)N---PVDF] during nanosecond pulsed 157-nm excimer laser irradiation. The chemical and electrical properties of these materials play important roles in many technologies. In PTFE, the primary mechanism for material removal involves bond scission along the backbone of the polymer. In PVDF, HF emission is accompanied by carbonization of the irradiated region. High-energy positive and negative ions are observed from both materials under 157-nm irradiation. We describe critical measurements that reveal the physics and chemistry underlying these processes.

Dickinson, Tom; George, Sharon; Langford, Steve

2009-03-01

125

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

PubMed

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

Kjeldsen, Peter; Scheutz, Charlotte

2003-11-01

126

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

127

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

128

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

129

Characterization and mechanism of side-effects of Oxygent HT (highly concentrated fluorocarbon emulsion) in swine.  

PubMed

Perfluorooctyl bromide is an oxygen-carrying perfluorocarbon presently under development as an artificial blood substitute (Oxygent HT). Intravenous (i.v.) Oxygent HT elicits a mild side-effect profile in man characterized by early onset headache and nausea and delayed onset fever. Early onset flushing has also been observed. Species of Artiodactyla are sensitive to particulate injections and demonstrate a transient pulmonary hypertensive response thought to be associated with the large number of pulmonary intravascular macrophages found in these species. Because of this sensitivity, we chose the swine as a model for further investigations. In anesthetized and conscious swine, i.v. Oxygent HT transiently increased mean pulmonary artery pressure (mPAP) and caused flushing. Both effects peaked at 30 min post injection and were resolved by 2 hrs. Plasma thromboxane B2 (TxB) increased in response to Oxygent HT. Oxygent HT-induced changes in mPAP, flush, and plasma TxB were blocked by aspirin and ibuprofen. Dexamethasone and SQ 29,548 (thromboxane receptor antagonist) blocked the mPAP increase. In conscious swine, Oxygent HT caused a febrile response which was blocked by ibuprofen or dexamethasone. Thus, both early- and late-onset effects of Oxygent HT in swine are blocked by interference with the arachidonic acid cascade. These findings suggest that the 2-phase "flu-like" syndrome induced by Oxygent HT is secondary to the release of products of the arachidonic acid cascade and may be effectively prophylaxed in man with corticosteroids or long plasma half-life cyclooxygenase inhibitors. PMID:7849964

Flaim, S F; Hazard, D R; Hogan, J; Peters, R M

1994-01-01

130

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

Code of Federal Regulations, 2010 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...

2010-07-01

131

Chemical vapor deposition and functionalization of fluorocarbon-organosilicon copolymer thin films  

E-print Network

Neural prostheses are micron-scale integrated circuit devices that are under development for the treatment of brain and spinal cord injuries. A key challenge in the fabrication of these silicon- based devices is the ...

Murthy, Shashi Krishna, 1977-

2003-01-01

132

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

...ARI Standard 700-1995. The test will show noticeable turbidity at chloride levels of about 3 ppm by weight or higher. ...The results of the test shall not exhibit any sign of turbidity. Report the results as “pass” or “fail.”...

2014-07-01

133

Sub-Millimeter Absorption Measurements of Temperature and Density in Fluorocarbon Plasmas  

NASA Astrophysics Data System (ADS)

Sub-millimeter (300 GHz to 1 THz) absorption spectroscopy is being developed as a diagnostic for measuring radical densities and temperatures in processing plasmas for microelectronics. Most molecules, radicals, and ions have transitions suitable for detection at these frequencies and the necessary spectroscopic data is available in the literature for determining the absolute radical densities. Initial measurements are being conducted with a backward-wave-oscillator (BWO) source and a liquid-He-cooled bolometer detector. The narrow linewidth (< 10 kHz) of the BWO is ideally suited for measuring the translational temperatures of radicals through the Doppler broadening of the absorption lineshape. Previous temperature measurements in an inductively coupled Gaseous Electronics Conference (GEC) Reference Reactor found all the radicals to have temperatures close to room temperature. Other spatially resolved plasma diagnostics, such as laser-induced fluorescence, in similar inductive sources have found significantly higher rotational temperatures within the plasma. The difference in plasma temperature diagnostic results is being investigated by measuring the radial density and temperature distributions. Initial results indicate that the low temperatures being measured with the BWO are probably due to the geometry of the GEC Reference cell which has a large volume of gas surrounding the plasma. This results in the line-integrated absorption signal of the BWO being dominated by the cooler, denser gas surrounding the plasma.

Benck, Eric; Siegrist, Karen; Plusquellic, David

2003-10-01

134

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

135

Fluorocarbon plasma etching and profile evolution of porous low-dielectric-constant silica  

E-print Network

related to the morphology of porous materials, the PS was treated as stoichiometric SiO2 . The model reactor. We found that etch rates ER for PS are generally higher than for SiO2 due to the inherent smaller applicable to PS. © 2003 American Institute of Physics. DOI: 10.1063/1.1562333 As microelectronic device

Kushner, Mark

136

Fluorocarbon polymer deposition kinetics in a low-pressure, high-density, inductively coupled plasma reactor  

Microsoft Academic Search

Maintaining dimensional control and adequate throughput during the etching of submicron features requires plasma etch tools that operate at low pressures and high densities, such as inductively coupled plasmas (ICPs). Unfortunately, in this regime, it has proven difficult to achieve a stable, reproducible chemistry for selective oxide etching of contacts and vias. In particular, it is difficult to control the

M. J. Sowa; M. E. Littau; V. Pohray; J. L. Cecchi

2000-01-01

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

Synthesis and Characterization of Stable Fluorocarbon Nanostructures as Drug Delivery Vehicles for Cytolytic Peptides  

PubMed Central

The therapeutic potential of cytolytic peptides is plagued by nonspecificity and enzymatic degradation. We report the first stable incorporation of melittin (a 26 amino acid amphipathic peptide) into an outer lipid monolayer of perfluorocarbon nanoparticles. Melittin binds avidly to the nanoparticles (dissociation constant ~3.27 nM) and retains its pore-forming activity after contact-mediated delivery to model bilayer membrane (liposomes) thereby demonstrating the effectiveness of perfluorocarbon nanoparticles as unique nanocarriers for cytolytic peptides. PMID:18302330

Soman, Neelesh R.; Lanza, Gregory M.; Heuser, John M.; Schlesinger, Paul H.; Wickline, Samuel A.

2009-01-01

139

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

SciTech Connect

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

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

1993-12-31

140

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

EPA Science Inventory

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

141

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

Microsoft Academic Search

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 ¹⁹F NMR. CDFA concentrations ranges from <7.1 to

Jonathan W. Martin; James Franklin; Mark L. Hanson; Keith R. Solomon; Scott A. Mabury; David A. Ellis; Brian F. Scott; D. C. G. Muri

2000-01-01

142

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

NASA Technical Reports Server (NTRS)

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

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

1979-01-01

143

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

144

Production Mechanism and Chemical Structure of Dust Particles in Fluorocarbon Plasmas  

NASA Astrophysics Data System (ADS)

Dust particles were found to be produced in octafluorocyclobutane (c-C4F8) plasmas used for reactive ion etching of silicon dioxide films and chemical vapor deposition of low dielectric constant films. The dust particles contained the ultrahigh mass polymers of 100 000 in molecular weight, which were compounds carbon-rich compared with deposited films and were formed from gas phase products related to C2F4. The ultrahigh mass polymers could work as nuclei, and were grown to be spherical micrometer-sized dust particles. The dust particle included crystalline grain of a few nanometer scale which corresponded to the nuclei size estimated form the molecular weight.

Takahashi, Kazuo; Ono, Kouichi; Setsuhara, Yuichi

2002-12-01

145

Stabilization of Ba2YCu3O7-? by Surface Coating with Plasma Polymerized Fluorocarbon Film  

NASA Astrophysics Data System (ADS)

High-Tc superconducting Ba2YCu3O7-? pellets were coated with polyfluorocarbon thin films prepared by plasma polymerization of tetrafluoroethene (C2F4). The polymer-coated Ba2YCu3O7-? preserved its high-Tc superconductivity even after it had been kept standing in water at 60°C, whereas the superconductivity of noncoated pellets was completely destroyed under the same condition. The high hydrophobicity of the film originated from high fluorine content is considered to be primarily responsible for the protection of the superconductor from chemical deterioration by preventing the hydrolysis at the surface.

Sato, Kota; Omae, Shinji; Kojima, Kuniharu; Hashimoto, Takuya; Koinuma, Hideomi

1988-11-01

146

Restoration of the interfacial properties of lung surfactant with a newly designed hydrocarbon/fluorocarbon lipid.  

PubMed

Serum proteins, especially fibrinogen, inactivate the lung surfactant mixture by adsorbing quickly and irreversibly to the alveolar air/aqueous interface. As a consequence of the inactivation, the surfactant becomes dysfunctional, and respiration cannot be maintained properly. Preventing the adsorption of surface active serum proteins to the air/water interface is important because this phenomenon causes fatal diseases such as acute respiratory distress syndrome (ARDS). Although some treatments exist, improvements in synthetic surfactants that can resist this inactivation are still expected. In this context, a novel ion pair lipid (IPL, CF3(CF2)7SO3(-)(CH2CH3)3N(+)(CH2OCH2)10(CH2)15CH3) has been designed and synthesized. This surfactant reduces the inhibitory effect of fibrinogen by selectively interacting with DPPC (dipalmitoylphosphatidylcholine) and mimicking some of the interfacial properties of the pulmonary surfactant protein B (SP-B). Surface pressure-area isotherms and fluorescence microscopy images demonstrate that IPL can mix and interact synergistically with DPPC due to its unique molecular structure. Hysteresis behaviors of the monolayers, which are composed of mixtures of DPPC and IPL at different molar ratios, indicate that with increasing amounts of IPL, the lipid losses from the interface induced by the presence of fibrinogen significantly decrease. It is also found that IPL is able to adsorb to monolayers formed in the presence of fibrinogen, whereas fibrinogen cannot penetrate the monolayers formed in the presence of IPL. These results indicate that by mimicking some of the interfacial properties of SP-B, this novel hybrid molecule is promising in terms of preventing fibrinogen adsorption and therefore resisting surfactant inactivation. PMID:25112907

Dilli, Gokce; Unsal, Hande; Uslu, Burcin; Aydogan, Nihal

2014-10-01

147

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

NASA Technical Reports Server (NTRS)

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

Atkinson, Roger

1990-01-01

148

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

SciTech Connect

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

Trowbridge, L.D.

1999-09-01

149

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

150

Direct fluorination of nitrogen-containing ladder polymers, two new [open quotes]graphitic[close quotes] fluorocarbon polymers  

SciTech Connect

Paracyanogen and pyrolyzed poly(acrylonitrile) have been perfluorinated using elemental fluorine and have retained their polymeric fused ring structures. The two new materials produced by this method were characterized by infrared spectroscopy, electron impact mass spectrometry, elemental analysis, iodometric titration, and thermogravimetric analysis. Some chemical and physical properties are discussed as well as several possible applications in light of the discussed properties of these materials. 21 refs., 4 figs., 3 tabs.

Kampa, J.J.; Lagow, R.J. (Univ. of Texas, Austin (United States))

1993-04-01

151

Integrated feature scale modeling of plasma processing of porous and solid SiO2 . I. Fluorocarbon etching  

E-print Network

insulators, and in particular, porous silicon-dioxide PS . Profile evolution and maintenance of critical on the average pore radius and porosity. However, the profile changes from tapered to bowed are their structural properties, which are porosity, average pore radius and pore interconnectivity.8 Measurements

Kushner, Mark

152

Customizable, multi-functional fluorocarbon nanoparticles for quantitative in vivo imaging using 19F MRI and optical imaging  

Microsoft Academic Search

Monitoring cell trafficking in vivo noninvasively is critical to improving cellular therapeutics, drug delivery, and understanding disease progression. In vivo imaging, of which magnetic resonance imaging (MRI) is a key modality, is commonly used for such monitoring. 19F MRI allows extremely specific detection and quantification of cell numbers directly from in vivo image data, longitudinally and without ionizing radiation. We

Mangala Srinivas; Luis J. Cruz; Fernando Bonetto; Arend Heerschap; Carl G. Figdor; I. Jolanda M. de Vries

2010-01-01

153

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

E-print Network

and deposition of metal barrier coatings into PS trenches were developed, and incorporated into a feature profile 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

Kushner, Mark

154

Conclusions and Federal actions  

NASA Technical Reports Server (NTRS)

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

1975-01-01

155

Coatings Based on Side-chain Ether-linked Poly(ethylene glycol) and Fluorocarbon Polymers for the Control of Marine Biofouling  

Microsoft Academic Search

The preparation of side group modified polystyrene-based surface-active block copolymers (SABC) for use as marine fouling resistance\\/release applications is described. Modifying moieties such as poly(ethylene glycol) (PEG) and semifluorinated segments were used. A novel bilayer methodology has been employed that provides both suitable mechanical properties through the use of an elastomeric primer layer of styrene-ethylene\\/butylene-styrene (SEBS) and control of surface-chemistry

Jeffrey P Youngblood; Luisa Andruzzi; Christopher K Ober; Alexander Hexemer; Edward J Kramer; James A Callow; John A Finlay; Maureen E Callow

2003-01-01

156

Fluorinated diamondlike carbon templates for high resolution nanoimprint lithography  

E-print Network

plasma etching. An antiadhesion coating was provided through fluorocarbon-based plasma treatment, which of the fluorocarbon plasma treatment was also demonstrated in the antiadhesion treatment of the nanoimprint resist

Hone, James

157

Atmospheric Halocarbons, Hydrocarbons, and Sulfur Hexafluoride: Global Distributions, Sources, and Sinks  

Microsoft Academic Search

The global distribution of fluorocarbon-12 and fluorocarbon-11 is used to establish a relatively fast interhemispheric exchange rate of 1 to 1.2 years. Atmospheric residence times of 65 to 70 years for fluorocarbon-12 and 40 to 45 years for fluorocarbon-11 best fit the observational data. These residence times rule out the possibility of any significant missing sinks that may prevent these

H. B. Singh; L. J. Salas; H. Shigeishi; E. Scribner

1979-01-01

158

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

159

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

Code of Federal Regulations, 2010 CFR

...Nitrate *Ethylene-Methacrylic Acid Copolymers *Ethylene-Vinyl Acetate Copolymers *Fatty Acid Resins *Fluorocarbon Polymers...Alpha)Olefins Polyacrylic Acid *Polyamides *Polyarylamides... *Polybutenes Polybutenyl Succinic Anhydride...

2010-07-01

160

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

161

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

162

Evaluation of the fatigue fracture resistance of unfilled and filled polytetrafluoroethylene materials  

Microsoft Academic Search

Polytetrafluoroethylenes (PTFEs) and their composites are a special class of fluorocarbons with very high chemical resistance and wide service temperature. This makes them good candidate materials for load-bearing components exposed to harsh environments, including some space applications. In the present work, fatigue crack propagation (FCP) behavior of four materials from the fluorocarbon family, including PTFE without filler (virgin PTFE), PTFE

H. Aglan; Y. Gan; M. El-Hadik; P. Faughnan; C. Bryan

1999-01-01

163

Room temperature stable perfluorocarbon emulsions with acceptable half-lives in the reticuloendothelial system.  

PubMed

Prolonged room temperature stability (i.e. zero particle growth) can be achieved for concentrated emulsions of perflubron (perfluorooctyl bromide) or perfluorodecalin via addition of a secondary high molecular weight, lipophilic fluorocarbon component. Due to their enhanced lipophilic character, the secondary fluorocarbon components have acceptable half-lives in the organs of the reticuloendothelial system. PMID:7849920

Weers, J G; Liu, J; Fields, T; Resch, P; Cavin, J; Arlauskas, R A

1994-01-01

164

Aerobic Preservation of Organs Using a New Perflubron\\/Lecithin Emulsion Stabilized by Molecular Dowels  

Microsoft Academic Search

The purpose of the study reported here was to explore a new strategy for the aerobic preservation of transplants using stable concentrated fluorocarbon emulsions as an oxygen delivery system. Fluorocarbons (FCs) are synthetic molecules, chemically and biologically inert, with a high oxygen-dissolving capacity. As they do not mix with water, it is necessary to emulsify them for intra-vascular use. Perfluorooctyl

Eric J. Voiglio; Leila Zarif; Fabien C. Gorry; Marie-Pierre Krafft; Jacqueline Margonari; Xavier Martin; Jean Riess; Jean Michel Dubernard

1996-01-01

165

Normothermic preservation of "multiple organ blocks" with a new perfluorooctyl bromide emulsion.  

PubMed

To evaluate the efficiency of fluorocarbon emulsions as oxygenating media for the normothermic preservation of organs (multiple organ blocks, MOB), a new perfluorooctyl bromide (perflubron) emulsion was compared with a mixture of modified Krebs solution and blood. The fluorocarbon emulsion used (90% w/v of fluorocarbon) contained a low amount of egg yolk phospholipid (EYP, 2% w/v) and was stabilized by a mixed fluorocarbon-hydrocarbon amphiphile C6F13C10H21 (F6H10). Blood of 4 rat MOBs was replaced with a 36% w/v fluorocarbon emulsion which has been complemented with albumin and electrolytes (EMOBs). 5 MOBs were perfused with a mixture of blood and albumin-containing Krebs solution (KBMOBs). Lactate, amylase and creatine kinase were lower (p < 0.05) at 60 and 120 min in EMOBs than in KBMOBs, PMID:7849957

Voiglio, E J; Zarif, L; Gorry, F; Krafft, M P; Margonari, J; Dubernard, J M; Riess, J G

1994-01-01

166

Lung functions after intravenous or intraperitoneal administration of perfluorooctyl bromide (PFOB) or perfluorotributylamine (FTBA) emulsions.  

PubMed

The biomechanical and oxygen transfer functions of lungs of animals administered intravenous or intraperitoneal fluorocarbon emulsions containing either perfluorotributylamine or perfluorooctyl bromide 4 to 7 days earlier were tested in a porcine and a canine model. Lung fluorocarbon content was measured by 19F NMR spectroscopy. The existence of fluorocarbon in the lung tissue produced no measurable effects on lung compliance variables in vivo or ex vivo nor on steady state oxygen transfer from air to blood over a wide range of inspired oxygen partial pressures. PMID:7849930

Millard, R W; McGoron, A J

1994-01-01

167

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

168

Origin, evolution, and control of sidewall line edge roughness transfer during plasma etching  

E-print Network

(cont.) micromasking. Porous films seem especially prone, perhaps due to polymer diffusion into the pore structure. Control of polymerization during the etch through the use of lower-polymerizing fluorocarbons or the ...

Rasgon, Stacy A., 1974-

2005-01-01

169

Circulation . Author manuscript Ultrafast and whole-body cooling with total liquid ventilation induces  

E-print Network

. MESH Keywords Animals ; Cardiopulmonary Resuscitation ; Disease Models, Animal ; Fluorocarbons ; Heart ; physiology ; Heart Arrest ; mortality ; physiopathology ; therapy ; Hypothermia, Induced ; methods ; Kidney ; Ventricular Fibrillation ; mortality ; physiopathology ; therapy Author Keywords Cardiopulmonary resuscitation

Paris-Sud XI, Université de

170

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

EPA Science Inventory

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

171

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

Code of Federal Regulations, 2010 CFR

...CH4 ) carbon monoxide (CO), carbon dioxide (CO2 ), and oxides...background levels of hydrocarbon, carbon monoxide, carbon dioxide, and oxides of nitrogen...on fluorocarbon-coated glass fiber filters or...

2010-07-01

172

40 CFR 92.114 - Exhaust gas and particulate sampling and analytical system.  

Code of Federal Regulations, 2010 CFR

...identifier. (A) Filters. Glass fiber filter paper is permitted for...4) of this section. (iii) Carbon monoxide and carbon dioxide measurements must be made... ) Fluorocarbon-coated glass fiber filters or...

2010-07-01

173

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

174

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

175

Condensing Heat Exchangers Optimize Steam Boilers  

E-print Network

The development of fluorocarbon resin covered tubes has advanced to the point where full scale marketing in connection with condensing heat exchangers has begun. Field installations show simple paybacks of one to one and a half years with resulting...

Sullivan, B.; Sullivan, P. A.

1983-01-01

176

Microcomputer Software for Refrigerant Property and Cycle Analysis Calculations  

E-print Network

for each fluorocarbon refrigerant, represent curve fits to existing tabular property data. For both ammonia and the fluorocarbon refrigerants, the equations for the following four basic properties of refrigerants are used. - Liquid density as a... often involve approximations from graphical data or tedious single-,' or sometimes double-interpola tions from tabular data. To provide a fast, accurate, and convenient alternative to these cumbersome procedures, REFRIG has been designed...

Bierschenk, J. L.; Strohl, S. T.; Schmidt, P. S.

177

The use of cavitation for the production of diver breathing gas  

E-print Network

. It was later shown that mice, rats, and dogs ' could survive when either submerged in or ventilated with hyperbarically oxygenated saline (Kylstra , Pegg ). Clark and Golan used oxygenated fluorocarbon liquid to support mice, cats, and dogs while immersed.... It was later shown that mice, rats, and dogs ' could survive when either submerged in or ventilated with hyperbarically oxygenated saline (Kylstra , Pegg ). Clark and Golan used oxygenated fluorocarbon liquid to support mice, cats, and dogs while immersed...

Klentzman, Chris Adam

2012-06-07

178

The Design and Synthesis of Highly Branched and Spherically Symmetric Fluorinated Macrocyclic Chelators  

PubMed Central

Two novel, highly fluorinated macrocyclic chelators with highly branched and spherically symmetric fluorocarbon moieties have been designed and efficiently synthesized. This is achieved by conjugating a spherically symmetric fluorocarbon moiety to the macrocyclic chelator DOTA, with or without a flexible oligo-oxyethylene linker between these two parts. As a result of the spherical symmetry, all 27 fluorine atoms in each fluorinated chelator give a sharp singlet 19F NMR signal. The hydrophilicity and the 19F relaxation behavior of fluorinated chelators can be modulated by the insertion of a flexible linker between the fluorocarbon moiety and the macrocyclic linker. These chelators serve as prototypes for 1H-19F dual-nuclei magnetic resonance imaging agents. PMID:20585414

Jiang, Zhong-Xing; Yu, Y. Bruce

2010-01-01

179

Influence of the 100% w/v perfluorooctyl bromide (PFOB) emulsion dose on tumour radiosensitivity.  

PubMed

The radiosensitizing effect of a 100% w/v emulsion of a fluorocarbon, PFOB, which carries 4 times more oxygen than does Fluosol-DA 20% emulsion, was studied on two human tumour xenografts (HRT18 and HT29) and the murine tumour EMT6. This effect was compared with that obtained with carbogen alone. The fluorocrit (amount of fluorocarbon in the blood) and haematocrit remained unchanged from 7 to 65 min post-injection of the emulsion (8 ml/kg). Tumour-bearing mice were pretreated with 100% w/v PFOB emulsion doses ranging from 2 to 15 ml/kg in the presence of carbogen for 30 min prior to and during irradiation. The fluorocrit increased from 1.5% to 9.5% as the dose of 100% w/v PFOB emulsion increased from 2 to 15 ml/kg. The haematocrit remained the same for all the fluorocarbon emulsion doses used. Tumour radiosensitization varied with the fluorocarbon emulsion dose. Clinically relevant doses (2-4 ml/kg) of the 100% w/v PFOB emulsion plus carbogen produced significantly more radiosensitization than carbogen alone, with sensitizing enhancement ratios of 1.4 for EMT6 and 1.7 for HRT18. The radiosensitivity of HRT18 cells was thus very close to that obtained with normally oxygenated cells. For higher doses (8-15 ml/kg) the radiosensitizing effect of 100% w/v PFOB emulsion plus carbogen becomes comparable to that of carbogen alone. These experiments show that clinically useful doses of 100% w/v PFOB plus carbogen produced tumour radiosensitization only at relatively low fluorocrits. Thus the fluorocrit, and hence the fluorocarbon's oxygen-carrying capacity, is not the only factor involved in radiosensitizing tumour cells by oxygen-carrying fluorocarbon emulsions. PMID:1671693

Thomas, C; Riess, J; Guichard, M

1991-02-01

180

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

181

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

182

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, sulfonated hydrocarbon-fluorocarbon random copolymers, semifluorinated trialkyltin fluorides and small hydrogen-bonding compounds have been evaluated. Random copolymers of styrene and heptadecafluorodecyl acrylate yielded substantial increases in viscosity. Falling cylinder viscometry results indicated that the 29%styrene--71%fluoroacrylate bulk-polymerized copolymer induced very significant viscosity increases at copolymer concentrations of 0.1--5.0wt%.

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

2000-02-02

183

Effect of the addition of 1-hexyl-2-(perfluoroalkyl)-1-iodoethenes on the stability and radiopacity of perfluorooctyl bromide emulsions  

Microsoft Academic Search

1-Hexyl-2-(perfluoroalkyl)-1-iodoethenes, CnF2n+1CH=CIC6H13(FnH6IE), with high biocompatibility and X-ray contrast ability, were investigated as additives and stabilizers in perfluorooctyl bromide (perflubron, PFOB)\\/egg yolk phospholipids (EYP) emulsions (90:4 w\\/v%), the fluorocarbon-based preparation presently best suited for diagnostic uses. These iodinated mixed fluorocarbon\\/hydrocarbon compounds, when used as additives in various amounts in PFOB emulsions (replacement of 3–30 w\\/v% of PFOB by FnH6IE), enhanced the

Véronique Sanchez; Jacques Greiner

1995-01-01

184

Chemistry of the surface and structural and adsorption properties of fluorinated carbon fiber and an adsorbent based on it  

NASA Astrophysics Data System (ADS)

The chemistry of the surface and structural and adsorption properties of fluorinated carbon fiber were studied by IR spectroscopy, gas chromatography, and static adsorption of vapors and dyes from aqueous solutions. Also, the quantitative characteristics of the influence of a binder (polytetrafluoroethylene) used to prepare a granulated adsorbent on the basis of the fiber were determined. The functional properties of the adsorbent were found to be largely determined by the properties of the initial fluorocarbon fiber. Fluorocarbons were shown to possess a developed porous structure and highly hydrophobic chemically homogeneous nonpolar surface for the adsorption of most of the organic compounds studied.

Zubareva, N. A.; Roshchina, T. M.; Khokhlova, T. D.; Shoniya, N. K.

2008-12-01

185

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

PubMed Central

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

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

2010-01-01

186

Flattening coefficient of aerosols collected on treated slides  

E-print Network

treated by immersion in this particular fluorocarbon surfactant solution (NYE BAR, Type CT 2! or 3M Chemical FC-721). Estimate of Precision Assuming a 1 . 5;l error in the measur ement of 0 , negligible error R. ' 34 in the measurement of f, and a +3... treated by immersion in this particular fluorocarbon surfactant solution (NYE BAR, Type CT 2! or 3M Chemical FC-721). Estimate of Precision Assuming a 1 . 5;l error in the measur ement of 0 , negligible error R. ' 34 in the measurement of f, and a +3...

Olan-Figueroa, Excel

2012-06-07

187

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

188

The Canadian Mineralogist Vol. 49, pp. 947-965 (2011)  

E-print Network

host of Zr, along with appreciable levels of the rare-earth elements (n 3 103 ppm REE + Y Evolution, Shool of Earth and Space Sciences, Peking University, Beijing 100871, People's Republic of China to the deposition of light-REE fluorocarbonates associated with calcite and minor fluorite. The fluid probably

Chakhmouradian, Anton

189

INSTITUTE OF PHYSICS PUBLISHING PLASMA SOURCES SCIENCE AND TECHNOLOGY Plasma Sources Sci. Technol. 15 (2006) 858864 doi:10.1088/0963-0252/15/4/032  

E-print Network

in fluorocarbon plasmas is essential for a fundamental understanding of plasma chemical processes and plasma. Other useful properties are their repellence against water and oil [4] and their potential molecules in the gas phase is essential for the understanding of these processes [8]. Various diagnostic

Greifswald, Ernst-Moritz-Arndt-Universität

190

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

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

191

Preliminary Evaluation of Greases to 600 F and Solid Lubricants to 1500 F in Ball Bearings  

Microsoft Academic Search

A special apparatus designed for the evaluation of high temperature lubricants in 20 mm bore ball bearings is described. The results of bearing runs at temperatures up to 1500 F in air are reported. Of the greases evaluated, a fluorocarbon grease, provided bearing lubrication for longer times at 450 and 600 F than either polyphenyl ether or silicone greases thickened

H. E. Sliney; R. L. Johnson

1968-01-01

192

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

PubMed Central

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 elllipsometry and AFM 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 mJ/m2 for untreated films to ~ 20–30 mJ/m2 after fluorination. XPS revealed a thin (from ~ 0.5 nm to ~ 3 nm) fluorocarbon layer on the DLC surface. Proposed mechanisms for the formation of this layer include two competing processes: etching of DLC and deposition of fluorocarbon material, with one or the other mechanism dominant depending on the plasma conditions. Fluorocarbon plasma-treated DLC molds for nanoimprint lithography were used to pattern sub-20 nm size features with a high degree of repeatability, demonstrating an extended lifetime of the anti-adhesion coating. PMID:19420525

Schvartzman, M.; Wind, S. J.

2009-01-01

193

Mask fabrication by nanoimprint lithography using antisticking layers  

Microsoft Academic Search

We have studied anti-sticking layers for nanoimprint lithography using different types of polymers, thermoplastic and thermosetting ones. Typically thermosetting polymers have higher mask selectivity in a fluorocarbon dry etch process than the thermoplastic polymers, but replication into these materials is much more complicated. We observe a high tendency for the polymer to adhere to the stamp. To minimize the sticking

H. Schulz; F. Osenberg; J. Engemann; Hella-C. Scheer

2000-01-01

194

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

195

The Great Spray Can Debate.  

ERIC Educational Resources Information Center

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

Bassow, Herb

196

Condensation of hydrocarbons – A review  

Microsoft Academic Search

Hydrocarbons are one of the candidates for refrigerants of next generation heat pump and refrigeration systems. Although the hydrocarbons have superior thermophysical properties as a refrigerant to fluorocarbons and are widely used in domestic refrigerators, their flammability prevents their wide application to larger systems, such as residential and packaged air conditioners, car air conditioners, heat pumps, etc. In this paper,

Akio Miyara

2008-01-01

197

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

NASA Technical Reports Server (NTRS)

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

McKinnon, Thomas; Todd, Paul; Oberdorster, Gunter

1996-01-01

198

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

199

Measurement of radiation damage on an optical reflector  

Microsoft Academic Search

We measured the radiation damage on an optical white fluorocarbon reflector called Goretex, which is to be used for aerogel threshold counters and crystal calorimeters of the BELLE detector of the KEK B-factory. Reflectance of the Goretex surface was monitored to see any effect of the radiation damage. Maximum equivalent dose was 8.6 Mrad. No radiation damage is observed within

K. C Peng; S. K Sahu; H. C Huang; K Ueno; Y. H Chang; C. H Wang; W. S Hou

1997-01-01

200

Partitioning of homologous nicotinic acid ester prodrugs (nicotinates) into dipalmitoylphosphatidylcholine (DPPC) membrane bilayers  

Microsoft Academic Search

The partitioning behavior of a series of perhydrocarbon nicotinic acid esters (nicotinates) between aqueous solution and dipalmitoylphosphatidylcholine (DPPC) membrane bilayers is investigated as a function of increasing alkyl chain length. The hydrocarbon nicotinates represent putative prodrugs, derivatives of the polar drug nicotinic acid, whose functionalization provides the hydrophobic character necessary for pulmonary delivery in a hydrophobic, fluorocarbon solvent, such as

Vivian Ojogun; Sandhya M. Vyas; Hans-Joachim Lehmler; Barbara L. Knutson

2010-01-01

201

Blood substitutes and other potential biomedical applications of fluorinated colloids  

Microsoft Academic Search

An oxygen carrying, heat-sterilized phospholipid-based emulsion of a fast excreted lipophilic fluorocarbon, perfluorooctyl bromide (perflubron), stabilized against molecular diffusion, has been developed to serve as a temporary blood substitute. It is expected to reduce exposure to donor blood and thereby help mitigate the pressure on our blood supply. A phase III clinical trial in Europe has demonstrated that use of

Jean G. Riess

2002-01-01

202

Buildings consume 41% of the nation's primary energy, of which equipment uses 57% to provide comfortable indoor  

E-print Network

comfortable indoor temperature and humidity levels, healthy air quality, heated water, and refrigeration cooling cycle eliminates the need for refrigerants (a significant contributor to global warming) while for refrigerator/ freezers that took effect in 1993. · In the 1990s under a CRADA with the Alternative Fluorocarbon

Oak Ridge National Laboratory

203

Quantitative Microinjection of Oocytes, Eggs, and Embryos Laurinda A. Jaffe and Mark Terasaki  

E-print Network

environment, such as membrane permeabilization, patch pipet dialysis, or use of a cell homogenate to the tip of the micropipet. Behind the mercury is an air space, and an oil-filled tube leading with a piece of teflon tubing. This assembly is filled with a fluorocarbon oil (Fluorinert). The microinjection

Terasaki, Mark

204

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

205

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...

206

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...

207

Uranium and microcracks in a 1,000-meter core, Redstone, New Hampshire  

NASA Astrophysics Data System (ADS)

The spatial distribution and mineralogical association of uranium in 30 samples of a 1,000 meter core from the Redstone (NH) Quarry were examined with fission track techniques, backscattered electron imaging, and energy dispersive X-ray spectrometry with the following results for the Conway and Mount Osceola granites: (1) Uranium occurs in microcracks sealed with siderite and/or with Ca+ RE fluorocarbonate minerals; the uranium contents of siderite and the RE fluorocarbonates are 1 to 30 ppm and 500 1,500 ppm, respectively. (2) Siderite and to a lesser extent RE fluorocarbonate minerals occur as replacement minerals of amphibole and biotite; the RE fluorocarbonates are the main alteration minerals of allanite. (3) The degree of alteration and the extent of uranium redistribution are greater in samples with major uraniferous microcracks. (4) The contents of Ca and Mn are approximately constant for siderite in sealed cracks throughout the Conway and Mount Osceola granites for the entire section penetrated by the corehole, approximately 700 meters. — From these observations, we conclude that an extensive set of fractures throughout a significant volume of the Mount Osceola and Conway granties were the conduits through which hydrothermal fluids containing CO2, uranium, and REs circulated. Microcracks facilitated fluid-rock interactions resulting in alteration and uranium redistribution. Certain primary uraniferous accessory minerals, i.e., allanite and ilmenorutile may have been the source for at least part of the uranium and REs that now occur in secondary minerals in these granites.

Caruso, Louis; Simmons, Gene

1985-06-01

208

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

209

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

210

SUPPORTING INFORMATION Control of initiation, rate, and routing of spontaneous capillary-driven flow of liquid  

E-print Network

unless otherwise noted. Fluorocarbon oils FC-40 (a mixture of perfluoro-tri-n-butyamine and perfluoro-di-n-butylmethylamine) and FC-3283 were obtained from 3M (St. Paul, MN). The fluorous surfactant 1H,1H,2H,2H-Perfluoro-1-octanol

Ismagilov, Rustem F.

211

Organic Rankine Cycles for the Petro-Chemical Industry  

E-print Network

and economically convert this type of heat flow into useful power. The system under development by MTI is one based on a conventional fluorocarbon refrigerant to generate a nominal 1000 kW from typical liquid and vapor streams in the process plant. The 220 F...

Rose, R. K.; Colosimo, D. D.

1979-01-01

212

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...

213

Affinity patterning of biomaterials using plasma gas discharge  

E-print Network

Patterned surfaces were prepared by combination of gas discharge and photolitographic processes. First a protein-repellent surface was prepared by glow discharge deposition of tri- and tetraglyme vapor on poly (ethylene terephtalate) surface, then on top of it fluorocarbon was deposited on selected domains by photolithography. Cell attachment was shown to be dependent of the surface hydrophilicity.

Goessl, A; Hoffman, A S; Jung, L

1996-01-01

214

Medical aerosol propellant interference with infrared anaesthetic gas monitors  

Microsoft Academic Search

fluorocarbons (CFC) as a medical aerosol propellant in an attempt to reduce damage to the ozone layer. This study compared the effects of HFA- and CFC-based inhalers on four anaes- thetic gas monitoring systems. Methods. The HFA- and CFC-based inhalers were activated in close proximity to the sample line of two Datex Ohmeda, an Agilent and a Siemens infrared anaesthetic

P. D. Levin; D. Levin; A. Avidan

2004-01-01

215

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

216

The Transition State for Metal-Catalyzed Dehalogenation: C-I Bond Cleavage on Ag(111)  

E-print Network

is the dissociation of carbon-iodine bonds which is used to create stable alkyl groups on many metal surfaces.3 picture of the nature of the transition state for carbon-iodine and carbon-chlorine bond cleavage on both- fluorocarbons (CFCs) into hydrofluorocarbons (HFCs).1,2 The most commonly studied catalyst

Gellman, Andrew J.

217

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

218

Mask fabrication by nanoimprint lithography using antisticking layers  

NASA Astrophysics Data System (ADS)

We have studied anti-sticking layers for nanoimprint lithography using different types of polymers, thermoplastic and thermosetting ones. Typically thermosetting polymers have higher mask selectivity in a fluorocarbon dry etch process than the thermoplastic polymers, but replication into these materials is much more complicated. We observe a high tendency for the polymer to adhere to the stamp. To minimize the sticking problem a fluorocarbon coating of the stamp was tested. It was deposited in a radio frequency plasma reactor with C4F8 as a feed gas. The thickness of the coating was several nm. It was characterized by contact angle measurement, XPS and FTIR analysis. Such coatings could successfully reduce sticking effects during an imprint process.

Schulz, Hubert; Osenberg, Frank; Engemann, J.; Scheer, Hella-Christin

2000-02-01

219

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

220

Aqueous Solution Properties of Pyridinium-Type Perfluorinated Surfactants and Simulation of Mixture CMC.  

PubMed

The critical micelle concentrations (CMCs) of 1,1,2,2-tetrahydroperfluoroalkylpyridinium chloride have been determined by measurements of surface tension and electrical conductivity, etc. The CMCs of perfluorinated surfactants were only about 0.02 times that of hydrocarbon one with the same carbon number. Aqueous solutions of fluorocarbon surfactants gave low surface tensions in comparison with those of hydrocarbon surfactants. The area per surfactant molecule at the air-water interface decreased with increasing length of the fluorocarbon chain. Electromotive force measurements were made with chloride-responsive electrodes on surfactants solutions. The micelle ionization degrees decreased with increasing length of the alkyl chain. The group contribution method simulated the mixture CMCs of binary surfactants with various alkyl chain lengths. The group contribution method proved to be very useful to predict not only the mixture CMCs but also the demixing regions of binary mixtures having great differences in CMC. Copyright 2001 Academic Press. PMID:11446820

Asakawa, Tsuyoshi; Ishikawa, Kenji; Miyagishi, Shigeyoshi

2001-08-01

221

Easy route to the wettability cycling of copper surface between superhydrophobicity and superhydrophilicity.  

PubMed

A hierarchical copper structure combining micro- and nanogaps/pores was built up on copper substrate by etching and electrodeposition. The fresh as-deposited copper was easily oxidized in air at room temperature, forming a CuO layer covering on the surface. The surface could be hydrophobized with thiol-modified fluorocarbons, after which it showed a water contact angle as high as 165° ± 2°. This surface could also regain the superhydrophilicity with a zero water contact angel after annealing at 200 °C for 10 min to desorb the low surface energy monolayer of thiol-modified fluorocarbons and reform a CuO layer again on the surface. Repeating the process of adsorption/desorption of the monolayer by modification and annealing, it was successful to fulfill the wettability cycling between superhydrophobicity and superhydrophilicity on the copper surface. The adsorption and desorption mechanism of the monolayer was discussed based on the result of surface chemistry analysis. PMID:22148586

Wang, Guoyong; Zhang, Tong-Yi

2012-01-01

222

A novel formulation of oxygen-carrying matrix enhances liver-specific function of cultured hepatocytes  

Microsoft Academic Search

Oxygen is an important component of the cellular microenvironment, mediating cell survival, differentiation, and function. Oxygen supply is a limit- ing factor during culture of highly metabolic cells such as hepatocytes. Here we present a simple formulation of a fluorocarbon-based oxygen carrier embedded in collagen gel that increases oxygen concentration in culture 6-fold. Rat hepatocytes cultured on oxygen carrier-collagen showed

Yaakov Nahmias; Yiannos Kramvis; Laurent Barbe; Monica Casali; Francois Berthiaume; Martin L. Yarmush

2006-01-01

223

Penetration of soil dust through woven and nonwoven fabrics  

Microsoft Academic Search

Several types of fabrics were laboratory?tested for their effectiveness in worker protection to pesticide?laden dust encountered in the agricultural environment. Of the applied <100 mesh dust, penetrations through knitted jersey and woven fabrics were greater than 87% and less than 5.8%, respectively. Treatment of woven fabrics with fluorocarbon polymers curtailed penetration by greater than 60%. Nonwoven fabrics allowed less than

Nasri S. Kawar; Francis A. Gunther; William F. Serat; Yutaka Iwata

1978-01-01

224

Contraband Detection with Nuclear Resonance Fluorescence: Feasibility and Impact  

SciTech Connect

In this report they show that cargo interrogation systems developed to thwart trafficking of illicit nuclear materials could also be powerful tools in the larger fight against contraband smuggling. In particular, in addition to detecting special nuclear materials, cargo scanning systems that exploit nuclear resonance fluorescence to detect specific isotopes can be used to help find: chemical weapons; some drugs as well as some chemicals regulated under the controlled substances act; precious metals; materials regulated under export control laws; and commonly trafficked fluorocarbons.

Pruet, J; Lange, D

2007-01-03

225

Polymer Composites for High-Temperature Proton-Exchange Membrane Fuel Cells  

Microsoft Academic Search

\\u000a Recent advances in composite proton-exchange membranes for fuel cell applications at elevated temperature and low relative\\u000a humidity are briefly reviewed in this chapter. Although a majority of research has focused on new sulfonated hydrocarbon and\\u000a fluorocarbon polymers and their blends to directly enhance high temperature performance, we emphasize on polymer\\/inorganic\\u000a composite membranes with the aim of improving the mechanical strength,

Xiuling Zhu; Yuxiu Liu; Lei Zhu

2009-01-01

226

Co-sputtered oxide thin film encapsulated organic electronic devices with prolonged lifetime  

Microsoft Academic Search

Effective top-side thin film encapsulation for organic light-emitting devices (OLEDs) was achieved by deposition of a multi-layer water diffusion barrier stack to protect the device against moisture permeation. The barrier stack was formed by alternative depositions of co-oxide and fluorocarbon (CFx) films. The co-oxide layer was fabricated by magnetron co-sputtering of silicon dioxide (SiO2) and aluminum oxide (Al2O3). While the

F. L. Wong; M. K. Fung; C. Y. Ng; A. Ng; I. Bello; S. T. Lee; C. S. Lee

227

Uptake of trifluoroacetate by Pinus ponderosa via atmospheric pathway  

NASA Astrophysics Data System (ADS)

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

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

228

Fuel cell ion-exchange membrane investigation  

NASA Technical Reports Server (NTRS)

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

Toy, M. S.

1972-01-01

229

Characterization and Application of a Planar Radio - Inductively-Coupled Plasma Source for the Production of Barrier Coatings  

Microsoft Academic Search

A planar radio-frequency (rf) inductively-coupled plasma (ICP) source is used to produce fluorocarbon discharges (CF_4\\/Ar) to fluorinate the surface of high-density polyethylene (HDPE). Using this system, concurrent studies of discharge characteristics, permeation properties of treated polymers and polymer surface characteristics are conducted to advance the use of plasma-fluorinated polymer surfaces as a barrier layer for automotive applications. Langmuir probes are

Leonard Joseph Mahoney

1994-01-01

230

Greenhouse effect of chlorofluorocarbons and other trace gases  

NASA Technical Reports Server (NTRS)

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

Hansen, James; Lacis, Andrew; Prather, Michael

1989-01-01

231

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

232

Nanoliter volume, high-resolution NMR microspectroscopy using a 60-\\/spl mu\\/m planar microcoil  

Microsoft Academic Search

Previous studies demonstrated the feasibility of using 100-?m inner diameter planar spiral inductors (microcoils) as detectors in 1H nuclear magnetic resonance (NMR) microspectroscopy. However, high-resolution NMR applications were not possible due to poor spectral resolution and low signal-to-noise ratio (SNR). These limitations in performance have now been largely overcome by using a nonconductive liquid fluorocarbon (FC-43) to minimize the effects

J. E. Stocker; T. L. Peck; A. G. Webb; M. Feng; R. L. Magin

1997-01-01

233

New substances for intraocular tamponades: perfluorocarbon liquids, hydrofluorocarbon liquids and hydrofluorocarbon-oligomers in vitreoretinal surgery  

Microsoft Academic Search

Perfluorocarbon liquids (PFCLs) and heavy fluorocarbon liquids (HFCLs) are being increasingly used as soft tools during vitreoretinal surgery. However, since long-term intraocular tolerance is still unsatisfactory, at present complete removal at the end of surgery is recommended. With the aim to improve long-term intraocular compatibility and to enlarge the spectrum of clinical applications, modified HFCLs have been developed. HFCL-oligomers with

Karin Kobuch; Dirk Henning Menz; Hans Hoerauf; Joachim Hans Dresp; Veit-Peter Gabel

2001-01-01

234

An XPS study of the fluorination of carbon anodes in molten NaF–AlF 3 –CaF 2  

Microsoft Academic Search

In the Hall–Héroult process for aluminum production electrolysis takes place in molten cryolite (NaF–AlF3–CaF2) with carbon electrodes. Dewetting of the anode leads to operational instability. A surface energy change due to surface\\u000a fluorocarbon formation during electrolysis is suggested as a contributing factor to diminishing the wettability of the anode.\\u000a In this work the surface composition of graphite anodes after electrolysis

Richard G. Haverkamp

235

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

236

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

237

Fluorophilicity of Alkyl and Polyfluoroalkyl 1 Nicotinic Acid Ester Prodrugs  

PubMed Central

The fluorophilicity of a series of hydrocarbon and fluorocarbon-functionalized nicotinic acid esters (nicotinates) is measured from their partitioning behavior (log KP) in the biphasic solvent system of perfluoro(methylcyclohexane) (PFMC) and toluene. The chain length of the hydrocarbon or fluorocarbon alkyl group of the ester ranges from one to twelve carbon atoms. Knowledge of the fluorophilicity of these solutes is relevant to the design of these prodrugs for fluorocarbon-based drug delivery. The experimental log Kp values range from ?1.72 to ?3.40 for the hydrocarbon nicotinates and ?1.64 to 0.13 for the fluorinated nicotinates, where only the prodrug with the longest fluorinated chain (2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctyl nicotinic acid ester) partitions preferentially into the fluorinated phase (log Kp = 0.13). Predictions of the partition coefficients using solubility parameters calculated from group contribution techniques or molecular dynamics simulation are in reasonable agreement for the perhydrocarbon nicotinates and short chained perfluorinated nicotinates (? 0.3%-39% deviation). Significant deviations from experimental partition coefficients (greater than 100%) are observed for the longest chain perfluoroalkyl nicotinates. PMID:20567608

Ojogun, Vivian; Knutson, Barbara L; Vyas, Sandhya; Lehmler, Hans-Joachim

2010-01-01

238

Hydrophobic Tail Length, Degree of Fluorination and Headgroup Stereochemistry are Determinants of the Biocompatibility of (Fluorinated) Carbohydrate Surfactants  

PubMed Central

A series of hydrocarbon and fluorocarbon carbohydrate surfactants with different headgroups (i.e., gluco-, galacto- and maltopyranoside) and (fluorinated) alkyl tails (i.e., C7 and C14 to C19) was synthesized to investigate trends in their cytotoxicity and haemolytic activity, and how surfactant-lipid interactions of selected surfactants contribute to these two measures of biocompatibility. All surfactants displayed low cytotoxicity (EC50 = 25 to > 250 ?M) and low haemolytic activity (EC50 = 0.2 to > 3.3 mM), with headgroup structure, tail length and degree of fluorination being important structural determinants for both endpoints. The EC50 values of hydrocarbon and fluorocarbon glucopyranoside surfactants displayed a “cut-off” effect (i.e., a maximum with respect to the chain length). According to steady-state fluorescence anisotropy studies, short chain (C7) surfactants partitioned less readily into model membranes, which explains their low cytotoxicity and haemolytic activity. Interestingly, galactopyranosides were less toxic compared to glucopyranosides with the same hydrophobic tail. Although both surfactant types only differ in the stereochemistry of the 4-OH group, hexadecyl gluco- and galactopyranoside surfactants had similar apparent membrane partition coefficients, but differed in their overall effect on the phase behaviour of DPPC model membranes, as assessed using steady-state fluorescence anisotropy studies. These observations suggest that highly selective surfactant-lipid interactions may be responsible for the differential cytotoxicity and, possible, haemolytic activity of hydrocarbon and fluorocarbon carbohydrate surfactants intended for a variety of pharmaceutical and biomedical applications. PMID:19481909

Li, Xueshu; Turanek, Jaroslav; Knotigova, Pavlina; Kudlackova, Hana; Masek, Josef; Parkin, Sean; Rankin, Stephen E; Knutson, Barbara L; Lehmler, Hans-Joachim

2009-01-01

239

Aerobic preservation of organs using a new perflubron/lecithin emulsion stabilized by molecular dowels.  

PubMed

The purpose of the study reported here was to explore a new strategy for the aerobic preservation of transplants using stable concentrated fluorocarbon emulsions as an oxygen delivery system. Fluorocarbons (FCs) are synthetic molecules, chemically and biologically inert, with a high oxygen-dissolving capacity. As they do not mix with water, it is necessary to emulsify them for intra-vascular use. Perfluorooctyl bromide (or perflubron) can be emulsifled with egg-yolk phospholipid (EYP), a nontoxic emulsifiant. The recent adjunction of amphiphilic fluorocarbon-hydrocarbon diblock molecules allows the obtaining of stable emulsions. By contrast with hemoglobin, fluorocarbons release oxygen following Henry's linear law rather than Barcroft's sigmoid curve. Release of oxygen by the FCs is only slightly influenced by temperature, which is an advantage for the preservation of organs. We tested a new 90% w/v fluorocarbon stem emulsion (perflubron/EYL/F6H10) diluted to 36% w/v with a hydroelectrolytic solution containing albumin, on four multiple organ blocks (MOBs; heart-lungs, liver, pancreas, kidneys, small intestine) of rats (EMOBs). Five control MOBs were perfused with a 50% v/v mixture of rat-blood and Krebs solution (KBMOBs). The lungs were ventilated with a FiO2 = 100%. In all cases the survival of the MOBs was greater than 210 min, with stable hemodynamics and preserved hydroelectrolytic and acid-base balances. The levels of lactate, amylase, and CK of the EMOBs were inferior (P < 0.05) to those of the KBMOBs between the first and the second hour. The diuresis of the EMOBs was higher (P < 0.05) than that of the KBMOBs (5.65 +/- 1.76 vs 1.21 +/- 0.28 mg/min). The production of bile, and the AST and ALT levels, were not significantly different. The PaO2 of the EMOBs was higher (P < 0.01) than for the KBMOBs. In normothermy, the maintenance of an aerobic metabolism using the FC emulsion caused less damage to the organs. Aerobic preservation of organs using FC emulsions therefore appears to be an attractive alternative to the presently used cold ischemia. PMID:8661239

Voiglio, E J; Zarif, L; Gorry, F C; Krafft, M P; Margonari, J; Martin, X; Riess, J; Dubernard, J M

1996-07-01

240

Hydrothermal rare earth mineralisation in carbonatites of the Tundulu complex, Malawi: Processes at the fluid/rock interface  

NASA Astrophysics Data System (ADS)

The Tundulu carbonatite complex in southeastern Malawi was intruded during the late Jurassic to early Cretaceous over three episodes. During the first and second episodes, the major rock types were calcite carbonatites, ankerite carbonatites, and apatite carbonatites. These rocks experienced hydrothermal alteration at the close of the second episode, during which quartz-baryte veins containing a significant level of rare earth fluorocarbonates were deposited. Veins in calcite carbonatites contain abundant synchysite [(La, Ce, Nd)Ca(CO 3) 2)F] with subordinate amounts of parisite [(La, Ce, Nd) 2Ca(CO 3) 3F 2] and bastnäesite [(La, Ce, Nd)CO 3F], crystallising in the order synchysite parisite ? bastnäesite. Some of the parisite is retrograde in origin, having formed as an alteration product from synchysite. Only synchysite has been identified in veins hosted by apatite carbonatites. However, bastnäesite predominates the hydrothermal assemblage in ankerite carbonatites. Parisite and synchysite have been found only as a fibrous fringe between wallrock ankerite and bastnäesite. The crystallisation sequence seen in calcite carbonatites represents a progressive depletion of both Ca 2+ and CO 2-3 in the fluids from which this mineral suite precipitated, with Ca 2+- and CO 2-3-poor phases precipitating last. Clearly, the predominance of bastnäesite in veins hosted by ankerite carbonatites suggests insufficient Ca 2+ and CO 2-3 in the fluids for the ubiquitous precipitation of synchysite and parisite. These observations are consistent with a model in which hydrothermal fluids reacted with the various wallrocks, which then released different amounts of Ca 2+ and CO 2-3, that subsequently reacted with REEs in the fluid to form the various fluorocarbonates. As such, the Tundulu carbonatites provide a natural laboratory in which compositional phase relationships of rare earth fluorocarbonates can be related to variations in the activities of Ca 2+ and CO 2-3 within the Ln(CO 3)F-CaCO 3-F 2(CO 3) -1 system.

Tendelo Ngwenya, Bryne

1994-05-01

241

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

242

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

243

Materials for encapsulation systems for terrestrial photovoltaic arrays  

NASA Technical Reports Server (NTRS)

The paper is concerned with glass and polymeric candidate materials and processes for potential encapsulation systems that could be used in low-cost long-life terrestrial photovoltaic arrays. The characteristics of encapsulation systems in use are reviewed, and the properties of proposed materials are examined. These materials include acrylics, epoxies, fluorocarbons, polycarbonates, polyesters, polyimides, polyxylylenes, and silicones. Properties of glass types are also considered. The prospects for glass and polymeric systems are analyzed, and the knowledge gained from a study of existing systems is discussed with attention to weather/aging effects, failures, environments, hazards, costs, development efforts, and materials choices.

Carmichael, D. C.; Gaines, G. B.; Sliemers, F. A.; Kistler, C. W.

1976-01-01

244

Evaluation of cytotoxicity of new semi-fluorinated amphiphiles derived from dimorpholinophosphate  

Microsoft Academic Search

Water-in-fluorocarbon reverse emulsions and microemulsions stabilized by semi-fluorinated amphiphiles derived from the dimorpholinophosphate polar head group, CnF2n+1(CH2)mOP(O)[N(CH2CH2)2O]2 (FnHmDMP), are being investigated as new delivery systems for drugs or genetic materials into the lung. Since information related to the toxicity of fluorinated surfactants is still very limited, we evaluated herein the cytotoxicity of a series of FnHmDMP (n=4, 6, 8 and

H. M Courrier; M. P Krafft; N Butz; C Porté; N Frossard; A Rémy-Kristensen; Y Mély; F Pons; Th. F Vandamme

2003-01-01

245

Mixed monolayers made from dipalmitoyl phosphatidylcholine and a fluorinated amphiphile  

Microsoft Academic Search

We have recently reported that water-in-fluorocarbon (FC) reverse emulsions and microemulsions could be used as delivery systems of bioactive materials to the lung, in particular for local administration using pressurized metered-dose inhalers. The surfactant involved in these reverse emulsions is a perfluoroalkylated amphiphile derived from the dimorpholinophosphate polar head group C8F17(CH2)11OP(O)[N(CH2CH2)2O]2 (F8H11DMP). The interaction of F8H11DMP with the lung surfactant

Hélène M. Courrier; Thierry F. Vandamme; Marie Pierre Krafft; Shohei Nakamura; Osamu Shibata

2003-01-01

246

New materials for solar cells - Tandem cells  

NASA Astrophysics Data System (ADS)

Cost efficiency in the manufacturing processes of the solar cell panels is discussed, noting the utilization of the III-V compound semiconductors (such as InSb or Ge) instead of silicon or gallium arsenide which have a complicated and expensive technology. A computation program is presented for a p-n junction using a set of nonlinear differential equations and taking into consideration such parameters as the mobility, the life space and the forbidden band. It is concluded that new, economic technologies should be directed toward blocking the UV light, acrylic elastomers, waterproof wood and paper materials and cost efficient silicon and fluorocarbon materials.

Dolocan, V.

247

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

NASA Technical Reports Server (NTRS)

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

1977-01-01

248

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

249

Development of a high-tensile-strain plastic-bonded TATB explosive  

SciTech Connect

Typical plastic-bonded explosives (PBX) with greater than 90 weight-percent explosive filler in a fluorocarbon binder have tensile strains which range from 0.2 to 0.6{percent}. We have recently developed a TATB-based PBX with a tensile strain approaching 1{percent} while maintaining a high-volume loading of the crystalline explosive component. We discuss our formulation efforts to design a TATB/poly(styrene-(ethylene-butylene)-styrene)(Kraton){sup 1} PBX and the critical processing parameters which affect the ultimate mechanical properties of this PBX. 9 refs., 3 figs., 5 tabs.

Pruneda, C.; McGuire, R.; Clements, R.

1990-04-05

250

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

251

Implementation of Ultrasonic Sensing for High Resolution Measurement of Binary Gas Mixture Fractions  

E-print Network

We describe an ultrasonic instrument for continuous real-time analysis of the fractional mixture of a binary gas system. The instrument is particularly well suited to measurement of leaks of a high molecular weight gas into a system that is nominally composed of a single gas. Sensitivity ultrasonic leak detection systems are also described. Although development of the described systems was motivated by the requirements of an evaporative fluorocarbon cooling system, the instrument is applicable to the detection of leaks of many other gases and to proce...

Bates, Richard; Berry, Stephane; Bitadze, Alexander; Bonneau, Pierre; Bousson, Nicolas; Boyd, George; Bozza, Gennaro; Crespo-Lopez, Olivier; Da Riva, Enrico; Degeorge, Cyril; Deterre, Cecile; DiGirolamo, Beniamino; Doubek, Martin; Favre, Gilles; Godlewski, Jan; Hallewell, Gregory; Hasib, Ahmed; Katunin, Sergey; Langevin, Nicolas; Lombard, Didier; Mathieu, Michel; McMahon, Stephen; Nagai, Koichi; Pearson, Benjamin; Robinson, David; Rossi, Cecilia; Rozanov, Alexandre; Strauss, Michael; Vitek, Michal; Vacek, Vaclav; Zwalinski, Lukasz

2014-01-01

252

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

PubMed Central

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

Jiang, Zhong-Xing; Yu, Y. Bruce

2007-01-01

253

A new concept for very low energy detonators and torches  

SciTech Connect

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 SCB ignition of the deposited films, and with the aluminum/copper oxide film, we observed a lower threshold for ignition of a powder pressed against the bridge. We also looked at other ignition methods including lasers, spark discharges, primers and hot combustion gases.

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

1996-03-01

254

Characterization of elastomeric materials with application to design  

NASA Technical Reports Server (NTRS)

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

Bower, Mark V.

1986-01-01

255

Perfluorocarbons and their use in Cooling Systems for Semiconductor Particle Detectors  

E-print Network

We report on the development of evaporative fluorocarbon cooling for the semiconductor pixel and micro-strip sensors of inner tracking detector of the ATLAS experiment at the future CERN Large Hadron Collider (LHC). We proceeded with studies using perfluoro-n-propane (3M-"PFG 5030"; C3F8), perfluoro-n-butane (3M-"PFG 5040"; C4F10), trifluoro-iodo-methane (CF3I) and custom C3F8/C4F10 mixtures. Certain thermo-physical properties had to be verified for these fluids.

Vacek, V; Ilie, S; Lindsay, S

2000-01-01

256

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

257

The morphology and chemistry evolution of fused silica surface after Ar/CF4 atmospheric pressure plasma processing  

NASA Astrophysics Data System (ADS)

In order to reveal the plasma etching processes on fused silica, the surface characterizations of fused silica after Ar/CF4 atmospheric pressure plasma processing were investigated. The morphology and chemistry evolution of fused silica surface were analyzed by AFM and XPS respectively. The AFM micrographs exhibited the three-dimensional surface topography and the RMS roughness changed with the increase of the material removal depth. The surfaces appeared to become smoother when the plasma etching occurred on the surface top layer. However, after the chemically modified layer was removed, etching resulted in the formation of a series of pits. During extended etching, the individual pits coalesced with one another, and the coalescence provided a means of reducing the depth of subsurface damage and the RMS roughness. The XPS results illustrated that small amount of radicals including C-CFn and CF-CFn could be introduced onto the fused silica surface during the Ar/CF4 plasma process, the fluorocarbon radicals were generated during CF4 plasma ionization. And the changes in relative concentration of the fluorocarbon radicals C-CFn with the removal depth were also studied.

Jin, Huiliang; Xin, Qiang; Li, Na; Jin, Jiang; Wang, Bo; Yao, Yingxue

2013-12-01

258

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

NASA Astrophysics Data System (ADS)

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

Nwankwo, L.

2013-12-01

259

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

260

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

261

Experimental study of spatial nonuniformities in 100 MHz capacitively coupled plasma using optical probe  

SciTech Connect

Plasma spatial nonuniformities in the 100 MHz rf driven capacitively coupled reactor used for reactive ion etching of 300 mm substrates were experimentally studied using a linear scanning optical emission spectroscopy probe. Radial profiles of plasma emission intensity were measured both in argon and fluorocarbon-containing gas mixtures in the pressure interval of 10-80 mTorr and the rf power range of 500-1250 W. It was demonstrated that the plasma emission profiles strongly depend on the working gas composition and pressure. The profiles have a bell-like shape at pressures about 10 mTorr for all gases. As the pressure increases, the profile shape becomes more complex with the central and peripheral peaks, and the amplitudes of the peaks strongly depend on the working gas composition. It is suggested that the emission profiles show plasma spatial nonuniformities that can influence the etching rate profiles obtained with such systems. According to the existing theoretical models, the most probable reasons for these plasma nonuniformities are charged particle radial diffusion at low pressures (about 10 mTorr), as well as the standing wave and skin and edge effects at higher pressures. Using the experimental emission profiles, the working conditions have been found that allow one to achieve the most uniform plasma for discharges in argon and fluorocarbon-containing gas mixtures.

Volynets, V. N.; Ushakov, A. G.; Sung, D.; Tolmachev, Y. N.; Pashkovsky, V. G.; Lee, J. B.; Kwon, T. Y.; Jeong, K. S. [Mechatronics and Manufacturing Technology Center, Samsung Electronics Co. Ltd., 416 Maetan-3 dong, Yeongtong-Gu, Suwon, Gyeonggi-Do 443-742 (Korea, Republic of)

2008-05-15

262

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

263

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

264

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

265

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

266

Synthesis of Polytetrafluoroethylene-like Films by a Novel Plasma Enhanced Chemical Vapor Deposition Employing Solid Material Evaporation Technique  

NASA Astrophysics Data System (ADS)

Polytetrafluoroethylene (PTFE)-like films were formed by electron cyclotron resonance (ECR) plasma enhanced chemical vapor deposition (ECR-PECVD) employing the solid material evaporation technique where the PTFE was evaporated by a CO2 laser resulting in the production of fluorocarbon species. This system does not employ any perfluorocompound (PFC) feed gases which cause global warming. In this system, it was found that C2F4 and higher species such as CxFy (x? 2) were generated by CO2 laser evaporation. The films were analyzed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared absorption spectroscopy (FT-IR). As a result, the chemical composition of films formed at microwave powers below 0.4 kW indicated a PTFE-like structure with an F/C ratio of 2.0 and a dielectric constant of 2.0. Densities of CFx (x=1--3) radicals and F atoms in the ECR plasma employing the solid material evaporation technique were measured to understand the behavior of these radicals by infrared diode laser absorption spectroscopy (IRLAS) and actinometric optical spectroscopy (AOES), respectively. From these measurements, higher species of C2F4 and CxFy were clarified to be the important precursors of PTFE-like fluorocarbon films.

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

2003-02-01

267

New Gas Chemistry for High-Performance SiO2 Patterning in Sub-0.1 mu m ULSIs  

NASA Astrophysics Data System (ADS)

SiO2 etching is done by using fluorocarbon gases to deposit a fluoropolymer on the underlying silicon. This deposit enhances the etching selectivity of SiO2 over silicon or silicon nitride. CF2 radicals are used as the main gas precursor for polymer deposition. In a conventional gas plasma, however, the CF2 radicals and other radicals (high-molecular-weight-radicals: CxFy) lead to polymerization. This condition causes microloading and etching-stop in high-aspect contact-hole patterning due to the sidewall polymerization during SiO2 etching processes. Conversely, by using new fluorocarbon gas chemistries (C2F4/CF3I), we achieved selective radical generation of CF2 and eliminated high-molecular-weight radicals. Under this condition, microloading-free and etching-stop-free high-aspect-ratio contact-hole patterning of SiO2 was accomplished. Thus, the higher molecular weight radicals play an important role in the sidewall polymerization in contact holes because these radicals have a higher sticking coefficient than CF2 radicals. Selective generation of CF2 radicals and suppression of CxFy radicals are thus necessary to eliminate microloading and etching-stop in the formation of high-aspect-ratio contact holes.

Samukawa, Seiji

2002-10-01

268

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

269

Evaluation of cytotoxicity of new semi-fluorinated amphiphiles derived from dimorpholinophosphate.  

PubMed

Water-in-fluorocarbon reverse emulsions and microemulsions stabilized by semi-fluorinated amphiphiles derived from the dimorpholinophosphate polar head group, C(n)F(2n+1)(CH(2))(m)OP(O)[N(CH(2)CH(2))(2)O](2) (FnHmDMP), are being investigated as new delivery systems for drugs or genetic materials into the lung. Since information related to the toxicity of fluorinated surfactants is still very limited, we evaluated herein the cytotoxicity of a series of FnHmDMP (n=4, 6, 8 and 10 and m=2, 5, and 11). Both solutions of FnHmDMP in fluorocarbons, and reverse water-in-fluorocarbon emulsions stabilized by FnHmDMP were assessed in order to determine the relation between surfactant structure and cell toxicity, and select the most innocuous emulsifier. A first short-term evaluation on mouse fibroblasts using a viability/cytotoxicity assay indicated that amphiphiles (in solution) with a chain length longer than C12 exhibit less toxicity than amphiphiles with shorter chain. Moreover cytotoxicity decreased also with length of the fluorinated segment. The protective effect of the fluorinated chain was strongly supported by the fact that the hydrogenated analog, C(15)H(31)OP(O)[N(CH(2)CH(2))(2)O](2) (H15DMP), was highly toxic. Qualitative evaluation on human lung epithelial cells (HLEC) using a colorimetric method (Mayer's hematoxylin) confirmed that amphiphiles (in solution) with longer chain were the least cytotoxic. The protective effect of the fluorinated chain appeared, however, to be significant only at low amphiphile concentrations (0.1% w/v). In contrast, at higher concentrations (1% and 5% w/v), the total chain length was the determining factor. Quantitative evaluation of the least cytotoxic amphiphiles using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) method then showed that F10H11DMP (in solution) was harmless until its solubility limit (1% w/v); cell growth was even enhanced due to improved oxygenation provided by the fluorocarbon phase. F8H11DMP exhibited some cytotoxicity at both 1% and 5% w/v, but the toxicity appeared to level off with concentration. Reverse water-in-perfluorooctyl bromide (PFOB) emulsions stabilized by either F10H11DMP or F8H11DMP were found to be non-cytotoxic. In conclusion, the present evaluation indicates that the cytotoxicity of FnHmDMP depends on both total and fluorinated amphiphile chain length, and leads us to select F8H11DMP and F10H11DMP as the less cytotoxic amphiphiles among a series of FnHmDMP compounds. Furthermore, water-in-fluorocarbon emulsions stabilized with F8H11DMP and F10H11DMP appeared to be non-cytotoxic towards HLEC in culture. PMID:12437963

Courrier, H M; Krafft, M P; Butz, N; Porté, C; Frossard, N; Rémy-Kristensen, A; Mély, Y; Pons, F; Vandamme, Th F

2003-02-01

270

Fluorinated proteins: from design and synthesis to structure and stability.  

PubMed

Conspectus Fluorine is all but absent from biology; however, it has proved to be a remarkably useful element with which to modulate the activity of biological molecules and to study their mechanism of action. Our laboratory's interest in incorporating fluorine into proteins was stimulated by the unusual physicochemical properties exhibited by perfluorinated small molecules. These include extreme chemical inertness and thermal stability, properties that have made them valuable as nonstick coatings and fire retardants. Fluorocarbons also exhibit an unusual propensity to phase segregation. This phenomenon, which has been termed the "fluorous effect", has been effectively exploited in organic synthesis to purify compounds from reaction mixtures by extracting fluorocarbon-tagged molecules into fluorocarbon solvents. As biochemists, we were curious to explore whether the unusual physicochemical properties of perfluorocarbons could be engineered into proteins. To do this, we developed a synthesis of a highly fluorinated amino acid, hexafluoroleucine, and designed a model 4-helix bundle protein, ?4H, in which the hydrophobic core was packed exclusively with leucine. We then investigated the effects of repacking the hydrophobic core of ?4H with various combinations of leucine and hexafluoroleucine. These initial studies demonstrated that fluorination is a general and effective strategy for enhancing the stability of proteins against chemical and thermal denaturation and proteolytic degradation. We had originally envisaged that the "fluorous interactions", postulated from the self-segregating properties of fluorous solvents, might be used to mediate specific protein-protein interactions orthogonal to those of natural proteins. However, various lines of evidence indicate that no special, favorable fluorine-fluorine interactions occur in the core of the fluorinated ?4 protein. This makes it unlikely that fluorinated amino acids can be used to direct protein-protein interactions. More recent detailed thermodynamic and structural studies in our laboratory have uncovered the basis for the remarkably general ability of fluorinated side chains to stabilize protein structure. Crystal structures of ?4H and its fluorinated analogues show that the fluorinated residues fit into the hydrophobic core with remarkably little perturbation to the structure. This is explained by the fact that fluorinated side chains, although larger, very closely preserve the shape of the hydrophobic amino acids they replace. Thus, an increase in buried hydrophobic surface area in the folded state is responsible for the additional thermodynamic stability of the fluorinated protein. Measurements of ?G°, ?H°, ?S°, and ?Cp° for unfolding demonstrate that the "fluorous" stabilization of these protein arises from the hydrophobic effect in the same way that hydrophobic partitioning stabilizes natural proteins. PMID:24883933

Marsh, E Neil G

2014-10-21

271

Characterization and Application of a Planar Radio - Inductively-Coupled Plasma Source for the Production of Barrier Coatings.  

NASA Astrophysics Data System (ADS)

A planar radio-frequency (rf) inductively-coupled plasma (ICP) source is used to produce fluorocarbon discharges (CF_4/Ar) to fluorinate the surface of high-density polyethylene (HDPE). Using this system, concurrent studies of discharge characteristics, permeation properties of treated polymers and polymer surface characteristics are conducted to advance the use of plasma-fluorinated polymer surfaces as a barrier layer for automotive applications. Langmuir probes are used to determine spatial distribution of charged-particle and space-potential characteristics in Ar and CF_4/Ar discharges and to show the influence of the spatial distribution of the heating regions and the reactor boundaries on the discharge uniformity. Langmuir probes are also used to identify rf anisotropic drift motion of electrons in the heating regions of the source and transient high-energy electron features in pulsed discharges. These latter features allow pulsed ICP sources to be operated at low time-averaged powers that are necessary to treat thermally sensitive polymers. Fourier Transform Infrared (FITR) spectroscopy is used to measure the dissociation of fluorocarbon gases and to explore differences between pulsed- and continuous -power operation. Dissociation levels of CF_4 (50-85%) using pulsed-power operation are as high as that for continuous operation, even though the net time -averaged power is far less with pulsed operation. The result suggests that pulsed fluorocarbon discharges possess high concentrations of chemically-active species needed for rapid surface fluorination. A gravimetric permeation cup method is used to measure the permeation rate of test fuels through HDPE membranes, and electron spectroscopy for chemical analysis (ESCA) studies are performed to determine the stoichiometry and thickness of the barrier layer. From these studies we find that a 50-70 A thick, polar, fluoro-hydrocarbon over layer reduces the permeation of isooctane/toluene/methanol mixtures by a factor of 4. To increase the permeation resistance for automotive applications, this result points towards the deposition of a 1000 A thick fluoro-hydrocarbon barrier coating with stoichiometry and bond structures similar to the CF_4/Ar treated HDPE.

Mahoney, Leonard Joseph

272

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

PubMed Central

Background Freon includes a number of gaseous, colorless chlorofluorocarbons. Although freon is generally considered to be a fluorocarbon of relatively low toxicity; significantly detrimental effects may occur upon over exposure. The purpose of the present study is to investigate whether occupational exposure to fluorocarbons can induce arterial hypertension, myocardial ischemia, cardiac arrhythmias, elevated levels of plasma lipids and renal dysfunction. Methods This comparative cross-sectional study was conducted at the cardiology clinic of the Suez Canal Authority Hospital (Egypt). The study included 23 apparently healthy male workers at the refrigeration services workshop who were exposed to fluorocarbons (FC 12 and FC 22) and 23 likewise apparently healthy male workers (unexposed), the control group. All the participants were interviewed using a pre-composed questionnaire and were subjected to a clinical examination and relevant laboratory investigations. Results There were no significant statistical differences between the groups studied regarding symptoms suggesting arterial hypertension and renal affection, although a significantly higher percentage of the studied refrigeration services workers had symptoms of arrhythmias. None of the workers had symptoms suggesting coronary artery disease. Clinical examination revealed that the refrigeration services workers had a significantly higher mean pulse rate compared to the controls, though no significant statistical differences were found in arterial blood pressure measurements between the two study groups. Exercise stress testing of the workers studied revealed normal heart reaction to the increased need for oxygen, while sinus tachycardia was detected in all the participants. The results of Holter monitoring revealed significant differences within subject and group regarding the number of abnormal beats detected throughout the day of monitoring (p < 0.001). There were no significant differences detected in the average heart rate during the monitoring period within subject or group. Most laboratory investigations revealed absence of significant statistical differences for lipid profile markers, serum electrolyte levels and glomerular lesion markers between the groups except for cholesterol and urinary ?2-microglobulin (tubular lesion markers) levels which were significantly elevated in freon exposed workers. Conclusions Unprotected occupational exposure to chlorofluorocarbons can induce cardiotoxicity in the form of cardiac arrhythmias. The role of chlorofluorocarbons in inducing arterial hypertension and coronary artery diseases is unclear, although significantly elevated serum cholesterol and urinary ?2-microglobulin levels raise a concern. PMID:19594908

2009-01-01

273

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

274

Economical Analysis about Ammonia Absorption Refrigeration Plants  

NASA Astrophysics Data System (ADS)

NH3-H2O absorption refrigeration plant is attractive from each standpoint of electric power saving, non-fluorocarbon and energy saving. The plant can be the economic alternative of power compression refrigeration for evaporation temperature range from 0°C to -60°C, using suitable waste heat (co-generation system, waste incinerator), oil and natural gas. In the application of the plant, the equipment cost and the COP must be reasonable from economical standpoint. Therefore, the paper shows the following. 1) Necessary heating temparature analysis for absorption plant 2) Equipment cost analysis for heating temperature 3) Equipment cost analysis for COP 4) Number of trays in the rectifying column for COP 5) Equipment cost analysis and COP in two-stage absorption

Takei, Toshitaka

275

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

276

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. PMID:23039185

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

2013-01-01

277

Investigation on surface structure of potassium permanganate/nitric acid treated poly(tetrafluoroethylene)  

NASA Astrophysics Data System (ADS)

In the previous articles concerning the treatment of poly(tetrafluoroethylene) (PTFE) with potassium permanganate/nitric acid mixture, the conversion of a hydrophobic to a hydrophilic surface was partially assigned to the defluorination of PTFE and then the introduction of carbonyl and hydroxyl groups into the defluorinated sites. In the present work, PTFE sheets were treated with potassium permanganate/nitric acid, and the surfaces before and after treatment were comparatively characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The surface sediments of the treated PTFE were also determined by atomic absorption spectroscopy (AAS). The results indicate that the conversion of the hydrophobicity to the hydrophilicity on the modified PTFE surface is mainly due to the deposition of hydrophilic manganese oxides which covered the fluorocarbon surface, and no detectable chemical reactions of PTFE occur in the treating process.

Fu, Congli; Liu, Shuling; Gong, Tianlong; Gu, Aiqun; Yu, Zili

2014-10-01

278

Nano-coatings on carbon structures for interfacial modification  

NASA Astrophysics Data System (ADS)

Surface modification of materials is a rapidly growing field as structures become smaller, more integrated and complex. It opens up the possibility of combining the optimum bulk properties of a material with optimized surface properties such as enhanced bonding, corrosion resistance, reactivity, stress transfer, and thermal, optical or electrical behavior. Therefore, surface functionalization or modification can be an enabling step in a wide variety of modern applications. In this dissertation several surface modification approaches on carbon foam and carbon nano-fibers will be discussed. These are recently developed sp2 graphitic carbon based structures that have significant potential in aerospace, automotive and thermal applications. Influence of surface modification on composite formation and properties have also been investigated. Two types of property changes have been investigated: one for enhancing the surface reactivity and another for surface inertness. Characterization techniques such as X-ray Photoelectron Spectroscopy (XPS), Atomic Force Microscopy (AFM), Contact Angle Measurement, Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and mechanical testing are used in this study to find out the influence of these coatings on surface composition, chemistry and morphology. Mechanical testing has been performed on composites and stand alone foam to study the influence of surface modification on physical and mechanical properties of the composite materials. The effectiveness of these coatings on metallic/graphite interface has also been investigated for metal-matrix composite related applications. Additionally, the influence of plasma coatings on nucleation and growth of nanotubes on larger carbon structures (to produce multiscale, multifunctional materials) have also been studied. It is seen that the liquid phase activation treatment introduces oxygen functional groups on the surface, but may cause severe enough degradation that damages the ligaments and cell walls of carbon foam. This results in higher elastic modulus but lower strength. So, to get any benefit from such approaches the optimization window may be very narrow and marginal in controllability. An alternative solution would be to synthesize ultra thin film coatings without etching the surfaces. It is observed that plasma assisted coatings having thickness in the range of few nanometers (4-5nm) are completely covering the graphite substrates. The coating surface chemistry and morphology information is based upon XPS and AFM studies on pyrolytic graphite substrate. Two types of plasma surface modification techniques have been attempted: one is to make the surface more reactive for structural components and the other is to make the surface more inert for stand-alone structures. In order to achieve these goals plasma assisted oxide and fluorocarbon coatings are studied in detail. The synthesized oxide and fluorocarbon coating chemistries are comparable to conventional silica (SiO2) and polytetrafluoroethylene (PTFE, -CF2-). It is seen that the fluorocarbon coatings provide moisture resistance to graphitic foam by making the surface inert at the nanometer scale. On the other hand, plasma assisted oxide coating is a feasible and effective means of improving the wettability and dispersion of foam and nanofibers in organic polymer matrix material. Surface analysis as well as microstructural studies and mechanical tests have shown encouraging results. The interface reactions between graphite (coated and uncoated) and epoxy have also been studied in detail. Nano-scale plasma coatings have also been applied for metal matrix composites and semiconductor related applications. The fluorocarbon coating promote delamination/exfoliation of the metal on graphite, hence may be used for patterning or lithography. Oxide coatings seem to enhance the adhesion and metallic diffusion between graphite and metal, hence can be used for the development of metal matrix composites. Additionally, oxide coating seems to enhance the length and density of nanotub

Pulikollu, Rajasekhar V.

279

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.

280

Long-lifetime thin-film encapsulated organic light-emitting diodes  

NASA Astrophysics Data System (ADS)

Multiple fluorocarbon (CFx) and silicon nitride (Si3N4) bilayers were applied as encapsulation cap on glass-based organic light-emitting diodes (OLEDs). When CFx/Si3N4 bilayers were deposited onto the OLED structure, the devices showed performance worse than one without any encapsulation. The adverse effects were attributed to the damage caused by reaction species during the thin-film deposition processes. To solve this problem, a CuPc interlayer was found to provide effective protection to the OLED structure. With a structure of CuPc/(CFx/Si3N4)×5, the encapsulated device showed an operation lifetime over 8000 h (higher than 80% of that achieved with a conventional metal encapsulation).

Wong, F. L.; Fung, M. K.; Tao, S. L.; Lai, S. L.; Tsang, W. M.; Kong, K. H.; Choy, W. M.; Lee, C. S.; Lee, S. T.

2008-07-01

281

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

NASA Astrophysics Data System (ADS)

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

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

2002-06-01

282

Dynamics and Spreading of pentanol and other alcohols for MEMS applications  

NASA Astrophysics Data System (ADS)

Microelectromechanical Systems (MEMS) have the potential to revolutionize widespread technologies, but tribological issues are currently preventing commercialization of some devices. Self-assembled monolayers (SAMs), while highly effective against release related stiction, are ineffective as MEMS lubricants [1]. Vapor phase lubrication has been proposed as a solution to the issue of tribological failure in MEMS with alcohol vapors attracting much interest. In an effort to understand the basic mechanisms of lubrication we have performed a quartz crystal microbalance (QCM) study of the uptake, sliding friction, and spreading rates of adsorbed alcohols on silicon and SAM treated substrates. [1] D. A. Hook, S. J. Timpe, M. T. Dugger, and J. Krim. Tribological degradation of fluorocarbon coated silicon microdevice surfaces in normal and sliding contact. J. Applied Physics 104 (2008).

Miller, Brendan; Hook, David; Krim, Jacqueline

2009-03-01

283

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

284

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

285

Pneumatic instrument gas bleed reduction strategy and practical application  

SciTech Connect

It has been common practice in the gas industry to power pneumatic instruments from natural gas. It was thought to be practical, inexpensive and harmless. In recent years, however, the view has changed. Methane is a potent greenhouse gas. The escape of methane into the Earth`s atmosphere contributes significantly to global warming. In fact, 18% of all global warming is now attributed to methane. The size of the methane problem is second only to carbon dioxide, and nearly twice the impact of the much discussed chlorinated fluorocarbons. This is a problem created by literally a million tiny flow streams, individually not a concern, but collectively, creating a threat to us all. In addition to the environmental impact, there are also safety, operational and financial impacts to consider. This article deals with cost-effective ways to stop or slow the pneumatic instrument related bleed of natural gas to the atmosphere.

Adams, M.; Livingston, D. [Fisher Controls International, Inc., Marshalltown, IA (United States)

1997-12-31

286

An enzyme-linked immunosorbent assay for detection of antibodies to maedi-visna virus in sheep. I. A simple technique for production of antigen using sodium dodecyl sulfate treatment.  

PubMed

We report the efficacy of an anionic detergent, sodium dodecyl sulfate (SDS) for preparing maedi-visna antigens for an indirect enzyme-linked immunosorbent assay (i-ELISA). Ovine maedi-visna virus (MVV) pelleted by differential centrifugation followed by liquid chromatography was treated with SDS or one of three lipid solvents: ethyl ether, chloroform or fluorocarbon. The SDS-treated antigen resulted in higher optical density values with positive serum and better discrimination between positive and negative serum samples from specific-pathogen-free (SPF) sheep experimentally inoculated with the virus. Optimal results were obtained when MVV was treated with concentrations of 0.25% and 0.125% of SDS. A viral antigen prepared by centrifugation and treatment of a viral pellet with SDS was also suitable for the i-ELISA. This latter technique may facilitate the production of MVV antigens for use in the i-ELISA. PMID:2174295

Simard, C L; Briscoe, M R

1990-10-01

287

Electrokinetics of Polar Liquids in Contact with Non-Polar Surfaces  

E-print Network

Zeta potentials of several polar protic (water, ethylene glycol, formamide) as well as polar aprotic (dimethyl sulfoxide) liquids were measured in contact with three non-polar surfaces using closed-cell electro-osmosis. The test surfaces were chemisorbed monolayers of alkyl siloxanes, fluoroalkyl siloxanes and polydimethylsiloxanes (PDMS) grafted on glass slides. All these liquids exhibited substantial electrokinetics in contact with the non-polar surfaces with these observations: the electrokinetic effect on the fluorocarbon-coated surface is the strongest; and on a PDMS grafted surface, the effect is the weakest. Even though these hygroscopic liquids contain small amounts of water, the current models of charging based on the adsorption of hydroxide ions at the interface or the dissociation of preexisting functionalities (e.g., silanol groups) appear to be insufficient to account for the various facets of the experimental observations. The results illustrate how ubiquitous the phenomenon of electro-kinetics ...

Lin, Chih-Hsiu; Chaudhury, Manoj K

2014-01-01

288

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

289

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

290

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

291

Synthesis and characterization of self-assembled monolayers on gold generated from partially fluorinated alkanethiols and aliphatic dithiocarboxylic acids  

NASA Astrophysics Data System (ADS)

The formation of novel self-assembled monolayers (SAMs) on gold from the adsorption of four distinct series of partially fluorinated alkanethiols (PFAs) and one series of chelating aliphatic dithiocarboxylic acids (ADTCAs) is reported. The SAMs were characterized by optical ellipsometry, contact angle goniometry, polarization modulation infrared absorption spectroscopy (PM-IRRAS), and X-ray photoelectron spectroscopy (XPS). The results for the PFA SAMs provided evidence for both the importance of oriented surface dipoles in influencing interfacial wettabilities and the significance of the degree of fluorination of the PFAs in determining the dispersive interfacial energies of the films. In addition, a series of PFA SAMs was used to demonstrate that the attenuation lengths of photoelectrons in fluorocarbon films are indistinguishable from those in hydrocarbon films. The results for the ADTCA SAMs demonstrated that the use of a chelating headgroup induces structural changes within the monolayers that influence the interfacial properties of the films.

Colorado, Ramon, Jr.

292

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

293

Results of apparent atomic oxygen reactions with spacecraft materials during shuttle flight STS-41G  

NASA Technical Reports Server (NTRS)

The effect of atomic oxygen interaction experienced by polymeric-based spacecraft materials is described. An experimental package (ACOMEX) flown on shuttle mission STS-41G carried out the investigation of advanced composite specimens such as carbon-epoxy and Kevlar-epoxy both with and without protective coatings added to thermal protective paints and films. Information on the exposure environment of the specimens was provided by a carbon coated atomic oxygen fluence monitor together with a photographic record. Mass loss measurements and photomicrographs made possible the analysis of the effect of interaction. After a total of about 38 hours of equivalent normal exposure at 225 km altitude the results showed that unprotected exposed surfaces exhibited severe erosion and mass loss with the possibility of seriously degrading structural and thermal performance. However, the specimens with a thin fluorocarbon overcoat showed promise of providing a protective barrier to the attack without altering the base properties of the material.

Zimcik, D. G.; Maag, C. R.

1985-01-01

294

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

295

Preliminary survey report: control technology for gallium arsenide processing at Hewlett Packard, San Jose, California  

SciTech Connect

A walk-through survey of the Hewlett Packard Company facility in San Jose, California, was prompted by an interest in the use of gallium arsenide as an alternative to silicon for the semiconductor industry. This facility produced gallium-arsenide and gallium phosphide Potential hazards existed from solvents, acids, and gases employed in wafer production. Some of the solvents included fluorocarbon compounds, xylene, and 1,1,1-trichloroethane Arsine, phosphine, hydrogen, and silane gases were used in the production processes. Worker exposures to gallium arsenide or arsenic dust were lower during the cleaning operation than they had been in other similar facilities, perhaps due to the small size of the crystal pullers used at this particular facility. According to the author, this facility is a possible candidate for an in-depth industry survey, but may not be representative of the entire industry.

Lenihan, K.L.

1987-04-01

296

Theoretical study of the Ar-, Kr-, and Xe-CH4, -CF4 intermolecular potential-energy surfaces.  

PubMed

We present a theoretical study of the intermolecular potentials for the Ar, Kr, and Xe-CH4, -CF4 systems. The potential-energy surfaces of these systems have been calculated utilizing second-order Möller-Plesset perturbation theory and coupled-cluster theory in combination with correlation-consistent basis sets (aug-cc-pvnz; n = d, t, q). The calculations show that the stabilizing interactions between the rare gases and the molecules are slightly larger for CF4 than for CH4. Moreover, the rare-gas-CX4 (X = H, F) potentials are more attractive for Xe than for Kr and Ar. Our highest quality ab initio data (focal-point-CCSD(T) extrapolated to the complete basis set limit) have been used to develop pairwise analytical potentials for rare-gas-hydrocarbon (-fluorocarbon) systems. These potentials can be applied in classical-trajectory studies of rare gases interacting with hydrocarbon surfaces. PMID:16970379

Alexander, William A; Troya, Diego

2006-09-21

297

The PICASSO Dark Matter Experiment  

NASA Astrophysics Data System (ADS)

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

Wichoski, Ubi

2011-12-01

298

Status of the Picasso Experiment  

NASA Astrophysics Data System (ADS)

The PICASSO experiment searches for cold dark matter through the direct detection of weakly interacting massive particles (WIMPs) via their spin-dependent interactions with fluorine at SNOLAB, Sudbury - ON, Canada. The detection principle is based on the superheated droplet technique; the detectors consist of a gel matrix with millions of liquid droplets of superheated fluorocarbon (C4F10) dispersed in it. The experiment has been taking data using 4.5-litre detector modules with approximately 80g of active mass per module. In this talk we will give an overview of the experiment, discuss the progress on the understanding of the superheated droplet technique and report on recent developments and future plans.

Wichoski, Ubi

2012-08-01

299

Electrical Conductance of Hydrophobic Membranes or What Happens Below the Surface  

PubMed Central

Nanoporous alumina membranes rendered hydrophobic by surface modification via covalent attachment of hydrocarbon or fluorocarbon chains conduct electricity via surface even when the pores are not filled with electrolyte. The resistance is many orders of magnitude higher than for electrolyte filled membranes and does not depend on the electrolyte concentration or pH but it does depend on the type of hydrophobic monolayer and its density. The corresponding surface resistance varies from greater than 1018 ?/? to less than 3×109 ?/?. When the hydrophobic monolayer contains a small proportion of photoactive spiropyran that is insufficient to switch the surface to hydrophilic after spiropyran photoisomerization to the merocyanine form, the membrane resistance also becomes light-dependent with a reversible increase of surface resistance by as much as 15%. Surface conduction is ascribed to hydration and ionization of the alumina surface hydroxyls and the ionizable groups of the hydrophobic surface modifiers. PMID:17542624

Vlassiouk, Ivan; Rios, Fabian; Vail, Sean A.; Gust, Devens; Smirnov, Sergei

2008-01-01

300

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

301

Encapsulation and Release of Amphotericin B from an ABC Triblock Fluorous Copolymer  

Microsoft Academic Search

Purpose  PEG-phospholipid-based micelles have been successfully used for the solubilization of several hydrophobic drugs but generally\\u000a lack sustained stability in blood. Our novel PEG-Fluorocarbon-DSPE polymers were designed to increase stability and improve\\u000a time-release properties of drug-loaded micelles.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  Novel ABC fluorous copolymers were synthesized, characterized, and used for encapsulation release of amphotericin B. FRET\\u000a studies were used to study micelle stability.\\u000a \\u000a \\u000a \\u000a \\u000a Results  The

Jun-Pil Jee; Aaron McCoy; Sandro Mecozzi

302

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

303

Channel electron multiplier compatibility with Viton and Apiezon-L vacuum grease  

SciTech Connect

Clean Viton and Viton coated with Apiezon-L vacuum grease were tested for their noncontaminating compatibility with channel electron multipliers (CEMs). The test setup and procedure were the same as those used previously in conjunction with CEM compatibility tests of certain epoxies, solder, and fluorocarbon polymer materials useful for construction of spaceflight sensors. While some CEM gain degradation was noted during exposure to Viton and Apiezon-L, the present tests indicate that, at least over instrument lifetimes of approx.2 x 10/sup 12/ counts, these materials should be suitable for (1) preflight space sensor testing systems, (2) hermetic seals for CEM-based space sensors, and (3) terrestrial CEM-based instrumentation.

McComas, D.J.; Baldonado, J.R.; Bame, S.J.; Barraclough, B.L.

1987-12-01

304

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

305

Electron ionization of open/closed chain isocarbonic molecules relevant in plasma processing: Theoretical cross sections  

NASA Astrophysics Data System (ADS)

In this paper, we report theoretical electron impact ionization cross sections from threshold to 2000 eV for isocarbonic open chain molecules C4H6, C4H8, C4F6 including their isomers, and closed chain molecules c-C4H8 and c-C4F8. Theoretical formalism employed presently, viz., Complex Scattering Potential-ionization contribution method has been used successfully for a variety of polyatomic molecules. The present ionization calculations are very important since results available for the studied targets are either scarce or none. Our work affords comparison of C4 containing hydrocarbon versus fluorocarbon molecules. Comparisons of the present ionization cross sections are made wherever possible, and new ionization data are also presented.

Patel, Umang R.; Joshipura, K. N.; Kothari, Harshit N.; Pandya, Siddharth H.

2014-01-01

306

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

307

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

308

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

309

Contamination rates of optical surfaces at 157 nm: impurities outgassed from construction materials and from photoresists  

NASA Astrophysics Data System (ADS)

Photo-induced contamination rates on 157-nm optical surfaces have been studied in controlled experiments with contaminants containing fluorocarbon, sulfur and iodine. The compounds investigated represent species generated in controlled outgassing studies of common construction materials and photoresists used in 157 nm steppers. No photocontamination was measured for highly fluorinated alkanes and ethers on an anti-reflective coating, at levels exceeding 10 ppm. Photocontamination with sulfur based compounds was similar to the behavior observed with hydrocarbon based derivatives. Sulfur containing residues, even from oxidized precursors, are fully cleanable in oxygen, with cleaning rates scaling proportionally with the level of oxygen. In contrast, at elevated levels of oxygen, non-volatile iodate complexes can form from iodine based contaminants. Sulfonium salts should therefore be considered over iodonium species in photoacid generators in 157 nm photoresists. In addition to studying these new classes of compounds, cleaning rates of hydrocarbon residues in trace levels of water were also studied.

Bloomstein, Theodore M.; Sedlacek, Jan H. C.; Palmacci, Stephen T.; Hardy, Dennis E.; Liberman, Vladimir; Rothschild, Mordechai

2003-06-01

310

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

311

Swarm studies on elementary processes and ion-molecule reactions in low-temperature plasmas  

NASA Astrophysics Data System (ADS)

This paper deals with the presentation and discussion of some recent measurements on the interaction of electron and ion swarms in gases, with particular emphasis on flourinated gases. The processes to be discussed are related to electron impact ionization and attachment, including Penning ionization and electron detachment. Electron transport is discussed in mixtures of SF6 and fluorocarbon gases, where interesting regions of negative differential conductivity have been observed in C2F4, and apparent pressure dependences of the drift velocity in C4F8. Ion transport is discussed in terms of recent measurements on positive and negative ions in SF6 and Ar. Finally, the subject of ion-molecule reactions is illustrated with the dissociation and charge transfer processes of daughter ions in nitrogen. Throughout the paper, the advantages and limitations of both the pulsed Townsend technique and the drift tube-mass spectrometer are highlighted.

de Urquijo, J.

2002-08-01

312

Development of Compact C2F4 Gas Supply Equipment and Its Application to Etching of Dielectrics in an Environmental Benign Process  

NASA Astrophysics Data System (ADS)

Compact C2F4 gas supply equipment, which controls the gas supply with sufficient accuracy by irradiation of a carbon dioxide laser (CO2) onto a solid source (PTFE) without using any fluorocarbon gas, has been developed to combat global warming. Although C2F4 gas has a very low Global Warming Potential (GWP <1), it is very unstable and thus considerably difficult to handle. This gas is used in the semiconductor manufacture process, where it is obtained from a conventional high-pressure cylinder. By changing the output of the laser, the amount of C2F4 gas generated can be precisely controlled in this equipment while also ensuring safety. The gas is supplied to the VHF excited parallel plate plasma reactor through a gas shower head with Ar carrier gas and, in actual tests, this environmental benign technology achieved high etching performances for low-k SiOCH and SiO2 films.

Takahashi, Shunji; Den, Shoji; Katagiri, Toshirou; Yamakawa, Koji; Kano, Hiroyuki; Hori, Masaru

2005-06-01

313

The characterization of octafluorocyclobutane-based plasma discharges for the selective etching and processing of silicon dioxide and low-K dielectric thin films  

NASA Astrophysics Data System (ADS)

Utilizing IRDLAS, and Langmuir probe measurements; we were able to demonstrate that C2F4 and CF2 are the main dissociation products in a C4F8 plasma discharge. Under conditions of energetic ion bombardment, C2F4 and CF2 are consumed at the wafer surface. Increases in ion energy increase the rate of consumption of C2F4 and CF2, resulting in increased SiO2 etch rates. The addition of Ar to the C4F8 discharge increased the ion flux in the discharge. The increased ion flux reduced the thickness of the fluorocarbon film, thus enhancing etch rates. During these experiments we were able to monitor SiF2 using UV-Vis absorption. From these experiments we determined that SiF2 is an important etch product of the SiO 2 etching process, due to its presence in high concentrations in the discharge. By using IRDLAS and XPS we were able to correlate changes in the surface chemistry during etching with changes in the neutral radical densities as a function of Ar addition to the discharge. The results of these experiments provided further evidence the ion energy, ion flux, and neutral radical flux all have important roles in the selective etch mechanism. Using the results from a parametric study we performed, we found that the roles of the ion energy, ion flux, and neutral radical flux are valid over a wide range of parameters. Additionally, by performing these studies on two different reactor platforms, we determined that our findings are not reactor dependent. We have shown that fluorocarbon plasmas can be used to modify the pore surface of porous silica. This modification process allowed us to decrease the dielectric constant of the porous silica film by the replacement of hydroxyl groups on the pore surface with fluorine. The plasma modified films allowed us greater control of the etch process, as was shown by the comparison of patterned plasma modified and as prepared EISA porous silica films. We have shown that hydroxyl radicals on the pore surface inhibit etching. We speculate that the hydroxyl radicals scavenge fluorine from the fluorocarbon layer, thereby rendering the film F-deficient. Due to this process surfaces with high hydroxyl concentrations required high ion energy to break through this layer and etch the underlying substrate. Conversely, pore surfaces where a fraction of the hydroxyl radicals have been replaced by fluorine enhance etching. We speculate both the reduction in the hydroxyl radicals and addition of fluorine allows the formation of a F-rich fluorocarbon layer. Due to the high surface area of the porous films, an increased amount of C2F 4 and CF2 were consumed, compared with SiO2 , thus the enhancement of the etch rate.

Barela, Marcos J.

2003-10-01

314

The use of atmospheric measurements to constrain model predictions of ozone change from chlorine perturbations  

NASA Technical Reports Server (NTRS)

Atmospheric photochemistry models have been used to predict the sensitivity of the ozone layer to various perturbations. These same models also predict concentrations of chemical species in the present day atmosphere which can be compared to observations. Model results for both present day values and sensitivity to perturbation depend upon input data for reaction rates, photodissociation rates, and boundary conditions. A method of combining the results of a Monte Carlo uncertainty analysis with the existing set of present atmospheric species measurements is developed. The method is used to examine the range of values for the sensitivity of ozone to chlorine perturbations that is possible within the currently accepted ranges for input data. It is found that model runs which predict ozone column losses much greater than 10 percent as a result of present fluorocarbon fluxes produce concentrations and column amounts in the present atmosphere which are inconsistent with the measurements for ClO, HCl, NO, NO2, and HNO3.

Douglass, Anne R.; Stolarski, Richard S.

1987-01-01

315

Multi-technique Characterization of Adsorbed Peptide and Protein Orientation: LK310 and Protein G B1  

SciTech Connect

The ability to orient biologically active proteins on surfaces is a major challenge in the design, construction, and successful deployment of many medical technologies. As methods to orient biomolecules are developed, it is also essential to develop techniques that can accurately determine the orientation and structure of these materials. In this study, two model protein and peptide systems are presented to highlight the strengths of three surface analysis techniques for characterizing protein films: time-of-flight secondary-ion mass spectrometry (ToF-SIMS), sum-frequency generation (SFG) vibrational spectroscopy, and near-edge x-ray absorption fine structure (NEXAFS) spectroscopy. First, the orientation of Protein G B1, a rigid 6 kDa domain covalently attached to a maleimide-functionalized self-assembled monolayer, was examined using ToF-SIMS. Although the thickness of the Protein G layer was similar to the ToF-SIMS sampling depth, orientation of Protein G was successfully determined by analyzing the C{sub 2}H{sub 5}S{sup +} intensity, a secondary-ion derived from a methionine residue located at one end of the protein. Next, the secondary structure of a 13-mer leucine-lysine peptide (LK{sub 310}) adsorbed onto hydrophilic quartz and hydrophobic fluorocarbon surfaces was examined. SFG spectra indicated that the peptide's lysine side chains were ordered on the quartz surface, while the peptide's leucine side chains were ordered on the fluorocarbon surface. NEXAFS results provided complementary information about the structure of the LK{sub 310} film and the orientations of amide bonds within the LK{sub 310} peptide.

Baio, J.; Weidner, T; Samuel, N; McCrea, K; Baugh, L; Stayton, P; Castner, D

2010-01-01

316

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

317

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. PMID:15679345

Roach, L. Spencer; Song, Helen; Ismagilov, Rustem F.

2006-01-01

318

Adsorption of gemini surfactants with partially fluorinated chains at three different surfaces: neutron reflectometry results.  

PubMed

The adsorption of six symmetrical cationic (dimethylammonium bromide) gemini surfactants with four different partially fluorinated chains at three different surfaces--the air/water, the hydrophilic silica/water, and the hydrophobic (octadecyltricholorosilane (OTS))/water--has been investigated by neutron reflectometry. The corresponding single chain trimethylammonium bromides have also been studied at the two solid surfaces. Four of the geminis with a C(6) spacer and chains with differing amounts of fluorocarbon have identical limiting areas per molecule at the air/water interface (106 ± 5 Å(2)). This is similar to the value for the corresponding hydrocarbon gemini with a C(6) spacer and C(12) side chains, but unlike the hydrocarbon gemini, it is significantly more than twice the area per molecule of the corresponding single chain cationic. In adsorbed aggregates on hydrophilic silica the area per molecule decreases from the air/water value by an average of about 25%, indicating a substantial improvement in the packing of these geminis in the aggregate, which can be attributed to the stronger interaction between the hydrophobic chains in the interior of the aggregates. On the hydrophobic OTS surface the area per molecule in the adsorbed monolayer for three partially fluorinated geminis decreased by about 15% from the air/water value, again indicating much more favorable packing next to the hydrophobic OTS, but for one of the geminis, fC(8)C(6)-C(6)-C(6)fC(8), the change in area was reversed. This reversal is accompanied by a marked thinning of the layer, which is attributed to a shift in the balance between the interactions of the hydrocarbon spacer and fluorocarbon chain fragments and the OTS surface. PMID:21166453

Li, Pei Xun; Dong, Chu Chuan; Thomas, Robert K; Wang, Yi Lin

2011-01-18

319

Three-stage multilayer formation kinetics during adsorption of an anionic fluorinated surfactant onto germanium. 1. Concentration effect.  

PubMed

The adsorption of tetraethylammonium perfluorooctylsulfonate (TEA-FOS) from aqueous solution onto hydroxylated germanium is studied using in situ polarized attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). The adsorption is monitored at a series of bulk solution concentrations spanning from well below to above the critical micelle concentration (CMC; 1.0 mM). The kinetics of adsorption is followed by monitoring the intensity of the fluorocarbon bands. The orientation of the fluorocarbon director with respect to the germanium surface is determined by circular dichroism measurements of CF2 stretching bands. At bulk concentrations ranging from 10% of the CMC to at least 500% of the CMC, the adsorption occurs in an unusual sequence of three stages. Initially, rapid adsorption occurs within 200 min, leading to coverage of a monolayer or less. A long period of slow adsorption follows, during which we hypothesize that surfactant molecules form clusters, some of which serve as nuclei for multilayer growth. This stage concludes suddenly with an acceleration in the rate of adsorption, which eventually leads to multilayer formation. Because this is an anionic surfactant adsorbing onto a negatively charged surface at pH 6, the tetraethylammonium ions must mediate the interactions between the surfactant headgroups and the surface. The dichroism measurements show that TEA-FOS is initially oriented randomly or somewhat parallel to the surface, but over time adopts an orientation somewhat normal to the surface. This behavior is consistent with initial adsorption at isolated sites, followed by aggregation into isotropic admicelles, and finally growth into flattened admicelles. The sudden onset of accelerated adsorption can be explained either by autoaccelerating adsorption or nucleation and growth of a hydrophobic multilayer structure. PMID:16471536

Xing, Rong; Rankin, Stephen E

2006-01-12

320

Transient and stable species kinetics in pulsed cc-rf CF4/H2 plasmas and their relation to surface processes  

NASA Astrophysics Data System (ADS)

Fluorocarbon plasmas are widely used in applications and as model systems for fundamental investigations of complex plasmas. In recent years pulsing of the rf discharge has been used as an additional parameter for process control, because many plasma parameters, e.g. densities and temperatures, become time dependent when the rf power is modulated. In this work tunable diode laser absorption spectroscopy in the mid-IR (IR-TDLAS) was applied to measure time-resolved densities of the transient species CF and CF2 and that of the stable product C2F4 in pulsed CF4/H2 asymmetrical capacitively coupled radio-frequency plasmas at 13.56 MHz. Simultaneously, the thickness of amorphous thin fluorocarbon films (a-C:F) on the powered electrode was determined by means of in situ ellipsometry. Therefore, it was possible to study the correlation between gas phase species and thin film formation. The decay curves of the CF and CF2 densities in the off-phase of the pulsed rf plasma were fitted with a combination of first and second order processes involving the loss processes of these radicals in the gas phase and at the surfaces. Particularly, in the plasma off-phase, the loss of CF2 radicals forming C2F4 was found to be dominant in the CF2 kinetics, but of minor importance for C2F4 production. Plasma process parameters such as total pressure, gas composition, power and power modulation were varied to investigate the interaction between gas phase species and surfaces.

Gabriel, O.; Stepanov, S.; Meichsner, J.

2007-12-01

321

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 spatially separated from the sample surface. Chemically reactive species are produced in the discharge region from rather inert feed gases. They exit the discharge region and travel in the afterglow towards the reaction chamber, where primarily neutral species arrive. The interaction with the sample surface is purely chemical. The absence of direct plasma surface interactions distinguishes remote plasma Chemical Dry Etching (CDE) from other etch processes like Reactive Ion Etching (RIE) or Inductively Coupled Plasma (ICP) etching. The etch reactions in CDE are isotropic, potentially offer great etch rate ratios and minimize substrate damage due to the absence of direct plasma-surface interactions. However, some materials like silicon dioxide (SiO2) or fluorocarbon deposits are difficult to remove because of the lack of activation energy otherwise provided by ion bombardment. In CDE, rates can be enhanced by the introduction of a new reaction pathway. Remote plasma CDE of silicon nitride (Si3N4) is an example for increasing the overall reaction rate by introducing a new reaction channel. Typically, the Si3N4 surface is exposed to the fluorine rich afterglow of a fluorocarbon, nitrogen trifluoride (NF 3) or sulfur hexafluoride (SF6) based discharge. We find that the Si3N4 etch rate is dramatically enhanced when Nitric Oxide (NO) is present in the afterglow as compared to the case in which only fluorine is present. Presented here are detailed analyses of the etching of Si3N 4 and SiO2 in different chemistries. Several experimental techniques are employed to investigate the composition of the plasma and the afterglow, the surface modifications and the etch rates for tetrafluoromethane (CF4) and NF3 based processes. These measurements establish the effect of NO on the Si3N4 etch rate. The dominant mechanism for the etch rate enhancement is shown by mass spectrometry measurements to be the production of N2 from NO and N from the Si3N 4 surface. These results were applied in the development of a new etch process that removes Si3N4 selectively over SiO 2 and silicon. Finally, the efficiency of different feed gases in remote plasma removal processes are compared.

Kastenmeier, Bernd E. E.

1999-09-01

322

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

323

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.

324

Damage by radicals and photons during plasma cleaning of porous low-k SiOCH. II. Water uptake and change in dielectric constant  

SciTech Connect

Porous dielectric materials provide lower capacitances that reduce RC time delays in integrated circuits. Typical low-k materials include porous SiOCH-silicon dioxide with carbon groups, principally CH{sub 3}, lining the pores. With a high porosity, internally connected pores provide pathways for reactive species to enter into the material. Fluorocarbon plasmas are often used to etch SiOCH, a process that leaves a fluorocarbon polymer on the surface that must later be removed. During cleaning using Ar/O{sub 2} or He/H{sub 2} plasmas, reactions of radicals that diffuse into the SiOCH and photons that penetrate into the SiOCH can remove -CH{sub 3} groups. Due to its higher reactivity, cleaning with Ar/O{sub 2} plasmas removes more -CH{sub 3} groups than He/H{sub 2} plasmas, and so produce more free radical sites, such as -SiO{sub 2} Bullet (a -SiO{sub 2}-CH{sub 3} site with the -CH{sub 3} group removed).Upon exposure to humid air, these free radical sites can chemisorb H{sub 2}O to form hydrophilic Si-OH which can further physisorb H{sub 2}O through hydrogen bonding to form Si-OH(H{sub 2}O). With the high dielectric constant of water, even a small percentage of water uptake can significantly increase the effective dielectric constant of SiOCH. In this paper, we report on results from a computational investigation of the cleaning of SiOCH using Ar/O{sub 2} or He/H{sub 2} plasmas and subsequent exposure to humid air. The authors found that plasma cleaning with He/H{sub 2} mixtures produce less demethylation than cleaning with Ar/O{sub 2} plasmas, as so results in less water uptake, and a smaller increase in dielectric constant. The water that produces the increase in dielectric constant is roughly half chemisorbed and half physisorbed, the latter of which can be removed with mild heating. Sealing the pores with NH{sub 3} plasma treatment reduces water uptake and helps prevent the increase in dielectric constant.

Shoeb, Juline; Kushner, Mark J. [Department of Electrical and Computer Engineering, Iowa State University, Ames, Iowa 50011 (United States); Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109-2122 (United States)

2012-07-15

325

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

326

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

327

Multi-functional Textiles for Military Applications  

NASA Astrophysics Data System (ADS)

The objective of this research was to develop the standard rip-stop weave military uniform fabric made of 50/50 nylon/cotton (NyCo) to achieve a repellent front surface and an antibacterial bulk for protection from chemical-biological warfare agents. Diallyldimethylammonium chloride (DADMAC), a quaternary ammonium salt monomer was graft polymerized on NyCo fabric to impart antimicrobial capability using atmospheric pressure glow discharge plasma. Plasma was used to induce free radical chain polymerization of the DADMAC monomer to introduce a graft polymerized network on the fabric with durable antimicrobial properties. Pentaerythritol tertraacrylate was used as a cross-linking agent to obtain a highly cross-linked, durable polymer network. The presence of polyDADMAC on the fabric surface was confirmed using acid dye staining, SEM, and TOF-SIMS. Antibacterial performance was evaluated using standard AATCC test method 100 for both gram positive and gram negative bacteria. Results showed 99.9% reduction in the bacterial activities of K. pneumoniae and S. aureus. To achieve repellency on NyCo front surface, an environmentally benign C6 fluorocarbon monomer, 2-(perfluorohexyl) ethyl acrylate was graft polymerized using plasma on the front surface of the NyCo fabric which was already grafted with polyDADMAC for anti-microbial properties. The surface was characterized by IR spectroscopy and XPS. The presence of fluorine on the surface was mapped and confirmed by TOF-SIMS. SEM images showed a uniform layer of fluorocarbon polymer on the fiber surface. High water contact angle of 144° was obtained on the surface. The surface also achieved a high AATCC Test Method 193 rating of 9 and AATCC Test Method 118 rating of 5, indicating that the surface could repel a fluid with surface tension as low as 24 dynes/cm. Appropriate experimental designs and statistical modeling of data helped identify the experimental space and optimal factor combinations for best response. The study helped create a multi-functional fabric with an anti-bacterial bulk, hydrophilic back surface and repellent front surface for enhanced protective and aesthetic values.

Malshe, Priyadarshini

328

Reactive Ion Etching of Carbon Nanowalls  

NASA Astrophysics Data System (ADS)

Two-dimensionally standing graphene sheets, i.e., carbon nanowalls (CNWs), were synthesized on a Si substrate employing a capacitively coupled fluorocarbon plasma-enhanced chemical vapor deposition system together with H radical injection. To apply CNWs in electronic devices and/or membrane filters, we have demonstrated the reactive ion etching (RIE) of CNWs. RIE employing H2/N2 gases showed that the CNW films were anisotropically etched at a relatively high rate of more than 250 nm/min. However, the 10-nm-thick interface layer between a CNW film and the Si substrate remained and the interface layer was not completely etched. In contrast, RIE employing Ar/H2 gases enabled us to completely remove the interface layer. Ar/H2 RIE was also carried out from the bottom surface of CNW films after exfoliating them from the Si substrate. As a result, a free-standing CNW film of 550 nm thickness without an interface layer as a membrane filter was successfully formed.

Kondo, Shingo; Kondo, Hiroki; Miyawaki, Yudai; Sasaki, Hajime; Kano, Hiroyuki; Hiramatsu, Mineo; Hori, Masaru

2011-07-01

329

Reviews of Infrared and Millimeter Waves. Vol. 2  

SciTech Connect

This book describes twenty of the most useful far-infrared (or submillimeter) lasers which are the only practical, powerful source of radiation between the wavelengths of one millimeter and ten micrometers. Hundreds of emission lines are listed, some providing hundreds of kilowatts of peak power in pulsed operation and others providing many tens of milliwatts of continuous power. Topics considered include far-infrared (FIR) laser lines in /sup 12/CH/sub 3/F and /sup 13/CH/sub 3/F; submillimeter laser lines in CD/sub 3/F; FIR laser lines optically pumped in methyl chloride; optical pumping of the CD/sub 3/Cl molecule; optical pumping of CF/sub 3/Br; optical pumping of the CD/sub 3/Br molecule; submillimeter lasers in methyl iodide; optically pumped CH/sub 3/OH; optically pumped deuterated methyl alcohol; optically pumped difluoromethane; optical pumping of fluorocarbon 12; submillimeter laser lines in CF/sub 2/CH/sub 2/; ammonia lasers; optically pumped D/sub 2/O; sulfur dioxide submillimeter wave lasers; optically pumped PH/sub 3/ lasers; optically pumped formic acid lasers; and optically pumped infrared laser action in propyne.

Button, K.J.; Inguscio, M.; Strumia, F.

1984-01-01

330

Durability of polymeric materials used in zinc/bromine flow batteries  

NASA Astrophysics Data System (ADS)

The lifetimes of zinc/bromine flow batteries may be limited by the durability of components which are fabricated from thermoplastic materials and exposed to the bromine-containing electrolyte. Examples of such components are flowframes and carbon-filled plastic electrodes. In early versions of the zinc/bromine battery, flowframes and electrodes were made from polypropylene and copolymers of propylene and ethylene. In later versions of the zinc/bromine battery, polyvinyl chloride (PVC) was used as the material to fabricate flowframes and polyethylene was used as the material used to fabricate both flowframes and electrodes. We found that carbon-plastic electrodes made from polypropylene or polypropylene rich copolymers were swelled and chemically attacked by the bromine-containing electrolytes. As a result, warpage occurred and the battery failed. On the basis of accelerated aging studies we estimated the lifetimes of the electrode and its polypropylene based component to be 96 and 10 months, respectively. The enhanced stability of the electrode was attributed to the presence of carbon which is known to be an antioxidant for thermoxidation. In accelerated exposure tests, bromine-containing electrolytes were also found to attack and leach out the additives used in PVC flowframes. PVC itself was only slightly degraded by the electrolyte. A commercial fluorocarbon, Tefzel, which contains no additives, was determined to be stable in bromine-containing electrolytes and is recommended as a replacement for PVC. Currently, aging studies on carbon-filled polyethylene electrodes are in progress.

Arnold, C., Jr.

331

Langmuir Probe Measurements of Inductively Coupled Plasmas in CF4/Ar/O2 Mixtures  

NASA Technical Reports Server (NTRS)

Fluorocarbon gases, such as CF4, and their mixtures are widely used in contemporary low-pressure and high-density plasma processing techniques. In such plasmas Langmuir probe is one of the most commonly employed diagnostic techniques to obtain electron number density (ne), electron temperature (Te), electron energy distribution function (EEDF), mean electron energy (Ee), ion number density (ni), and plasma potential (Vp). In this paper we report probe data for planar inductively coupled plasmas in CF4/O2/Ar mixtures. By varying the relative concentrations in the mixture, radial profiles of ne, ni, Te, Ee, Vp, EEDF were measured in the mid-plane of the plasma at 10 mTorr and 20 mTorr of gas pressures, and 200 W and 300 W of RF powers. Data show that ne and ni decrease with increase of CF4 content and decrease of gas-pressure but they increase with increase of RF-power, whereas Vp increases with decrease of gas-pressure and remains independent of RF-power. However, they all peak at the center of the plasma and decrease towards the edge while Te follows the other way and increases a little with increase of power. The measured EEDFs exhibit Druyvesteyn-like distribution at all pressures and powers. Data are analyzed and will be presented.

Rao, M. V. V. S.; Meyyappan, M.; Sharma, S. P.

2000-01-01

332

The effect of die materials and pressure-dependent slip on the extrusion of linear low-density polyethylene  

SciTech Connect

The flow of linear low-density polyethylene through stainless-steel slit dies occurred at shear rates approximately 12{percent} higher than in identical {alpha}-brass dies at the same wall shear stresses, indicating near-wall slip. The flow curves were independent of gap spacing. We show through the slip theory of Hill and co-workers [J. Rheol. {bold 34}, 891{endash}918 (1990)] that a measurable gap dependence of the flow curve is not a necessary consequence of wall slip; the flow curves for both stainless steel and {alpha}-brass dies can be fit with the same rheological parameters, with a difference in the work of adhesion accounting for the differences in the flow curves. X-ray photoelectron spectroscopy revealed differences in the chemistry of brass surfaces with different pretreating, corresponding to small differences in flow curves. Fluorocarbon-coated die surfaces showed no more slip than stainless steel, while the flow curve with gold-coated surfaces followed stainless steel at intermediate stress and brass at high stress. {copyright} {ital 1997 Society of Rheology.}

Person, T.J.; Denn, M.M. [Materials Sciences Division, Lawrence Berkeley National Laboratory] [Materials Sciences Division, Lawrence Berkeley National Laboratory; [Department of Chemical Engineering, University of California at Berkeley, Berkeley, California 94720-1462 (United States)

1997-03-01

333

ZEP520A cold-development technique and tool for ultimate resolution to fabricate 1Xnm bit pattern EB master mold for nano-imprinting lithography for HDD/BPM development  

NASA Astrophysics Data System (ADS)

Poor solvent developers are effective for resolution enhancement on a polymer-type EB resist such as ZEP520A. Another way is to utilize "cold-development" technique which was accomplished by a dip-development technique usually. We then designed and successfully built a single-wafer spin-development tool for the cold-development down to -10degC in order to dissolve difficulties of the dip-development. The cold-development certainly helped improve ZEP520A resolution and hole CD size uniformity, and achieved 35nm pitch BPM patterns with the standard developer ZED-N50, but not 25nm pitch yet. By employing a poor solvent mixture of iso-Propyl Alcohol (IPA) and Fluoro-Carbon (FC), 25nm pitch BPM patterns were accomplished. However, the cold-development showed almost no improvement on the IPA/FC mixture developer solvent. This paper describes cold-development technique and a tool, as well as its results, for ZEP520A resolution enhancement to fabricate 1Xnm bits (holes) for EB master-mold for Nano-Imprinting Lithography for 1Tbit/inch2 and 25nm pitch Bit Patterned Media development.

Kobayashi, Hideo; Iyama, Hiromasa

2012-06-01

334

A search for the prewetting line. [in binary liquid system at vapor-liquid interface  

NASA Technical Reports Server (NTRS)

This paper describes efforts to locate the prewetting line in a binary liquid system (isopropanol-perfluoromethylcyclohexane) at the vapor-liquid interface. Tight upper bounds were placed on the temperature separation (0.2 K) between the prewetting line and the line of bulk liquid phase separation. The prewetting line in systems at equilibrium was not detected. Experimental signatures indicative of the prewetting line occurred only in nonequilibrium situations. Several theories predict that the adsorption of one of the components (the fluorocarbon, in this case) at the liquid-vapor interface should increase abruptly, at a temperature sightly above the temperature at which the mixture separates into two liquid phases. A regular solution calculation indicates that this prewetting line should have been easily detectable with the instruments used in this experiment. Significant features of the experiment are: (1) low-gradient thermostatting, (2) in situ stirring, (3) precision ellipsometry from the vapor-liquid interface, (4) high resolution differential index of refraction measurements using a novel cell design, and (5) computer control.

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

1986-01-01

335

Plasma-assisted nanoscale protein patterning on Si substrates via colloidal lithography.  

PubMed

Selective immobilization of proteins in well-defined patterns on substrates has recently attracted considerable attention as an enabling technology for applications ranging from biosensors and BioMEMS to tissue engineering. In this work, a method is reported for low-cost, large scale and high throughput, selective immobilization of proteins on nanopatterned Si, based on colloidal lithography and plasma processing to define the areas (<300 nm) where proteins are selectively immobilized. A close-packed monolayer of PS microparticles is deposited on oxidized Si and, either after microparticle size reduction or alternatively after metal deposition through the PS close-packed monolayer, is used as etching mask to define SiO2 nanoislands (on Si). C4F8 plasma was used to selectively etch and modify the SiO2 nanoislands while depositing a fluorocarbon layer on the Si surface. The plasma-treated surfaces were chemically characterized in terms of functional group identification through XPS analysis and reaction with specific molecules. Highly selective protein immobilization mainly through physical adsorption on SiO2 nanoislands and not on surrounding Si was observed after C4F8 plasma-induced chemical modification of the substrate. The thickness of the immobilized protein monolayer was estimated by means of AFM image analysis. The method reported herein constitutes a cost-efficient route toward rapid, large surface, and high-density patterning of biomolecules on solid supports that can be easily applied in BioMEMS or microanalytical systems. PMID:24180245

Malainou, A; Tsougeni, K; Ellinas, K; Petrou, P S; Constantoudis, V; Sarantopoulou, E; Awsiuk, K; Bernasik, A; Budkowski, A; Markou, A; Panagiotopoulos, I; Kakabakos, S E; Gogolides, E; Tserepi, A

2013-12-19

336

Enhanced condensation heat transfer  

SciTech Connect

For the past four years, work has been in progress at ORNL to develop improved condensers for geothermal binary power cycles. The work has centered on optimizing the design variables associated with fluted surfaces on vertical tubes and comparing the tube performance with available enhanced tubes either for vertical or horizontal operation. Data with seven fluids including a hydrocarbon, fluorocarbons, and ammonia condensing on up to 30 different tubes have been obtained. Data for tubes of different effective lengths (1/2 to 4 ft) and inclination have also been obtained. The primary conclusion from this work is that the best fluted tubes can provide an enhancement in condensation coefficient by a factor of approximately 6 over smooth vertical tube performance and a factor of approximately 2 over the best enhanced commercial tubes either operating vertically or horizontally. These data, together with field test data have formed the basis for designing two prototype condensers, one for the 60 kWe Raft River, Idaho, pilot plant and one for the 500 kWe East Mesa, California, direct-contact demonstration plant.

Michel, J.W.; Murphy, R.W.

1980-01-01

337

Lubricant replacement in rolling element bearings for weapon surety devices  

SciTech Connect

Stronglink switches are a weapon surety device that is critical to the nuclear safety theme in modem nuclear weapons. These stronglink switches use rolling element bearings which contain a lubricant consisting of low molecular weight polytetrafluoroethylene (PTFE) fragments. Ozone-depleting solvents are used in both the manufacture and application of this lubricant. An alternate bearing lubrication for stronglink switches is needed that will provide long-term chemical stability, low migration and consistent performance. Candidates that were evaluated include bearings with sputtered MoS{sub 2} on the races and retainers, bearings with TiC-coated balls, and bearings with Si{sub 3}N{sub 4} balls and steel races. These candidates were compared to the lubricants currently used which are bearings lubricated with PTFE fragments of low molecular weight in a fluorocarbon solvent. The candidates were also compared to bearings lubricated with a diester oil which is representative of bearing lubricants used in industrial applications. Evaluation consisted of cycling preloaded bearings and subjecting them to 23 gRMS random vibration. All of the candidates are viable substitutes for low load application where bearing preload is approximately 1 pound. For high load applications where the bearing preload is approximately 10 pounds, bearings with sputtered MoS{sub 2} on the races and retainers appear to be the best substitutes. Bearings with TiC-coated balls also appear to be a viable candidate but these bearings did not perform as well as the sputtered MoS{sub 2}.

Steinhoff, R.; Dugger, M.T.; Varga, K.S. [Sandia National Laboratories, Albuquerque, NM (United States)

1996-05-01

338

Fluorine-Rich Planetary Environments as Possible Habitats for Life  

PubMed Central

In polar aprotic organic solvents, fluorine might be an element of choice for life that uses selected fluorinated building blocks as monomers of choice for self-assembling of its catalytic polymers. Organofluorine compounds are extremely rare in the chemistry of life as we know it. Biomolecules, when fluorinated such as peptides or proteins, exhibit a “fluorous effect”, i.e., they are fluorophilic (neither hydrophilic nor lipophilic). Such polymers, capable of creating self-sorting assemblies, resist denaturation by organic solvents by exclusion of fluorocarbon side chains from the organic phase. Fluorous cores consist of a compact interior, which is shielded from the surrounding solvent. Thus, we can anticipate that fluorine-containing “teflon”-like or “non-sticking” building blocks might be monomers of choice for the synthesis of organized polymeric structures in fluorine-rich planetary environments. Although no fluorine-rich planetary environment is known, theoretical considerations might help us to define chemistries that might support life in such environments. For example, one scenario is that all molecular oxygen may be used up by oxidation reactions on a planetary surface and fluorine gas could be released from F-rich magma later in the history of a planetary body to result in a fluorine-rich planetary environment.

Budisa, Nediljko; Kubyshkin, Vladimir; Schulze-Makuch, Dirk

2014-01-01

339

Fluorescence-Based Bacterial Overlay Method for Simultaneous In Situ Quantification of Surface-Attached Bacteria?  

PubMed Central

For quantification of bacterial adherence to biomaterial surfaces or to other surfaces prone to biofouling, there is a need for methods that allow a comparative analysis of small material specimens. A new method for quantification of surface-attached biotinylated bacteria was established by in situ detection with fluorescence-labeled avidin-D. This method was evaluated utilizing a silicon wafer model system to monitor the influences of surface wettability and roughness on bacterial adhesion. Furthermore, the effects of protein preadsorption from serum, saliva, human serum albumin, and fibronectin were investigated. Streptococcus gordonii, Streptococcus mitis, and Staphylococcus aureus were chosen as model organisms because of their differing adhesion properties and their clinical relevance. To verify the results obtained by this new technique, scanning electron microscopy and agar replica plating were employed. Oxidized and poly(ethylene glycol)-modified silicon wafers were found to be more resistant to bacterial adhesion than wafers coated with hydrocarbon and fluorocarbon moieties. Roughening of the chemically modified surfaces resulted in an overall increase in bacterial attachment. Preadsorption of proteins affected bacterial adherence but did not fully abolish the influence of the original surface chemistry. However, in certain instances, mostly with saliva or serum, masking of the underlying surface chemistry became evident. The new bacterial overlay method allowed a reliable quantification of surface-attached bacteria and could hence be employed for measuring bacterial adherence on material specimens in a variety of applications. PMID:17308176

Muller, Rainer; Groger, Gerhard; Hiller, Karl-Anton; Schmalz, Gottfried; Ruhl, Stefan

2007-01-01

340

Effect of Dichlorodifluoromethane on the Appearance, Viability, and Integrity of Escherichia coli  

PubMed Central

Cultures of Escherichia coli H52 were treated with liquid dichlorodifluoromethane (fluorocarbon-12 [f-12]) for 2 h at 22 C and then examined microscopically. Treated cells tended to clump, and their cytoplasms were generally less dense and less uniform in appearance than those of control cells. E. coli ML30 was exposed to f-12 at a concentration of 1.25 × saturation for times up to 1,200 min at 22 C. Cells were examined for changes in viability (plate count), permeability (as measured by exit of ?-[14C]methylglucoside or uptake of o-nitrophenyl-?-D-galactopyranoside), release of compounds absorbing at 260 nm, and lysis (changes in absorbance at 420 nm). Large losses of ?-methylglucoside and of percentage of viability occurred after brief exposure to f-12. Release of compounds absorbing at 260 nm occurred more slowly than the aforementioned events, possibly because these molecules are larger than ?-methylglucoside. During 1,200-min exposure to f-12, the number of survivors decreased from 109 to 104 organisms/ml, the loss of compounds absorbing at 260 nm amounted to 50% and 32% lysis occurred. Most of these changes occurred during the first 300 min of treatment. Loss of ?-methylglucoside was almost complete after 1-min exposure to f-12. These results suggest that death of the cell involves several stages, with a change of permeability occurring first, followed by leakage of compounds of increasing size and, finally, lysis. Images PMID:1096819

Prior, B. A.; Fennema, O.; Pate, J.

1975-01-01

341

In situ CF3 Detection in Low Pressure Inductive Discharges by Fourier Transform Infrared Spectroscopy  

NASA Technical Reports Server (NTRS)

The detection of CF(x) (x=1-3) radicals in low pressure discharges using source gases such as CF4 and CHF3 is of importance to the understanding of their chemical structure and relevance in plasma based etching processes. These radicals are known to contribute to the formation of fluorocarbon polymer films, which affect the selectivity and anisotropy of etching. In this study, we present preliminary results of the quantitative measurement of trifluoromethyl radicals, CF3, in low pressure discharges. The discharge studied here is an inductively (transformer) coupled plasma (ICP) source in the GEC reference cell, operating on pure CF4 at pressures ranging from 10 - 100 mTorr, This plasma source generates higher electron number densities at lower operating pressures than obtainable with the parallel-plate capacitively coupled version of the GEC reference cell. Also, this expanded operating regime is more relevant to new generations of industrial plasma reactors being used by the microelectronics industry. Fourier transform infrared (FTIR) spectroscopy is employed to observe the absorption band of CF3 radicals in the electronic ground state X2Al in the region of 1233-1270/cm. The spectrometer is equipped with a high sensitivity HgCdTe (MCT) detector and has a fixed resolution of 0.125/cm. The CF3 concentrations are measured for a range of operating pressures and discharge power levels.

Kim, J. S.; Cappelli, M. A.; Sharma, S. P.; Arnold, J. O. (Technical Monitor)

1998-01-01

342

Temporal variation of the electron density in afterglow of high-density CF_4, C_4F_8, and CF_4--H2 plasmas  

NASA Astrophysics Data System (ADS)

The kinetics of electrons in electronegative plasmas is greatly affected by dissociative attachment to neutral molecules, which is a major process for the formation of negative ions. In fluorocarbon plasmas, negative fluorine ions (F^-) are produced by electron attachment to various reaction products as well as the parent gas. In the present work, we have measured the temporal variation of the electron density in the afterglow of high-density CF_4, C_4F_8, and CF_4--H2 plasmas. A conventional microwave interferometer at 35 GHz was adopted for the measurement. The electron loss frequency was evaluated from the temporal variation of the electron density which was calculated from the interferometry signal digitized with a high sampling rate of 100 MHz. In CF4 plasmas, the variation of the electron loss frequency roughly corresponded to that of the neutral radical densities. In C_4F8 plasmas, the electron loss frequency was higher for the discharge condition with lower dissociation degree. These results indicates that reaction products play important roles for the production of F^- in CF4 plasmas, while in C_4F8 plasmas, the production of F^- is governed by the parent gas. No correlations were found between the electron loss frequency and the F atom density in CF_4--H2 plasmas, which suggests that the production of F^- from F2 is nearly negligible.

Sasaki, K.; Kadota, K.

1998-10-01

343

Structural investigation of nonionic fluorinated micelles by SANS in relation to mesoporous silica materials.  

PubMed

In an attempt to answer the question if there is dependence between the pore ordering of the mesoporous silica, obtained through the cooperative template mechanism, and the shape of the micellar aggregates of the surfactant solutions, the micellar structures of two nonionic fluorinated surfactant based-systems are studied by SANS. By fitting the experimental spectra with theoretical models, the structural evolution of the molecular aggregates can be described, and some important parameters can be obtained, such as the water and eventually oil penetration into the surfactant film, the aggregation number, the area per polar head of the surfactant, and the surfactant chain conformations. We have shown that for the C(8)F(17)C(2)H(4)(OC(2)H(4))(9)OH system, the micelles are prolate spheroids. The increase of the surfactant concentration in water does not change the characteristics of the interfacial film, but the aggregation number raises and the particles become more elongated. By contrast, the experimental curves of C(7)F(15)C(2)H(4)(OC(2)H(4))(8)OH cannot be fitted considering a small particle model. However, progressive incorporation of fluorocarbon induces a change of size and shape of the globules, which become smaller and more and more spherical. Regarding the material mesopore ordering, it appears that the micelles that lead to hexagonal mesoporous silica materials are described with a model of quasi-spherical globules. On the contrary, when large micelles are found, only wormhole-like structures are obtained. PMID:22145934

Michaux, Florentin; Blin, Jean-Luc; Teixeira, José; Stébé, Marie José

2012-01-12

344

Fast prototyping of injection molded polymer microfluidic chips  

NASA Astrophysics Data System (ADS)

We present fast prototyping of injection molding tools by the definition of microfluidic structures in a light-curable epoxy (SU-8) directly on planar nickel mold inserts. Optimized prototype mold structures could withstand injection molding of more than 300 replicas in cyclic olefin copolymer (COC) without any signs of failure or release. The key parameters to avoid mold failure are maximum adhesion strength of the epoxy to the nickel insert and minimum interfacial energy of the epoxy pattern to the molded polymer. Optimal molding of microstructures with vertical sidewalls was found for nickel inserts pre-coated by silicon oxide before applying the structured epoxy, followed by coating of the epoxy by a fluorocarbon layer prior to injection molding. Further improvements in the mold stability were observed after homogeneous coating of the patterned epoxy by a second reflowed layer of epoxy, likely due to the resulting reduction in sidewall steepness. We employed the latter method for injection molding bondable polymer microfluidic chips with integrated conducting polymer electrode arrays that permitted the culture and on-chip analysis of cell spreading by impedance spectroscopy.

Steen Hansen, Thomas; Selmeczi, David; Larsen, Niels B.

2010-01-01

345

Chemical Vapor Deposition of Fluoroalkylsilane Monolayer Films for Adhesion Control in Microelectromechanical Systems  

SciTech Connect

We have developed a new process for applying a hydrophobic, low adhesion energy coating to microelectromechanical (MEMS) devices. Monolayer films are synthesized from tridecafluoro-1,1,2,2-tetrahydrooctyltrichlorosilane (FOTS) and water vapor in a low-pressure chemical vapor deposition process at room temperature. Film thickness is self-limiting by virtue of the inability of precursors to stick to the fluorocarbon surface of the film once it has formed. We have measured film densities of {approx}3 molecules nm{sup 2} and film thickness of {approx}1 nm. Films are hydrophobic, with a water contact angle >110{sup o}. We have also incorporated an in-situ downstream microwave plasma cleaning process, which provides a clean, reproducible oxide surface prior to film deposition. Adhesion tests on coated and uncoated MEMS test structures demonstrate superior performance of the FOTS coatings. Cleaned, uncoated cantilever beam structures exhibit high adhesion energies in a high humidity environment. An adhesion energy of 100 mJ m{sup -2} is observed after exposure to >90% relative humidity. Fluoroalkylsilane coated beams exhibit negligible adhesion at low humidity and {<=} 20 {micro}J m{sup -2} adhesion energy at >90% relative humidity. No obvious film degradation was observed for films exposed to >90% relative humidity at room temperature for >24 hr.

MAYER,THOMAS M.; DE BOER,MAARTEN P.; SHINN,NEAL D.; CLEWS,PEGGY J.; MICHALSKE,TERRY A.

2000-01-26

346

Two episodes of acute illness in a machine shop  

SciTech Connect

Following an explosion in a machine shop and temporary plant closure, on the day the plant returned to full operations a degreaser malfunctioned. Workers in the assembly room were exposed to trichloroethylene levels later estimated to have exceeded 220 ppm (OSHA PEL 100 ppm). The plant was evacuated and the degreaser taken out of operation. Blood testing for carbon monoxide (CO) on five employees found carboxyhemoglobin levels in excess of normal. The plant reopened the following morning. Over the next two weeks, 15 employees were seen by the plant nurses for similar complaints; although all returned to work, their carboxyhemoglobin levels, later found to be inaccurate, were reported by a local medical clinic to range from 13.7 to 20.0 percent. At the end of the second week, another outbreak of illness occurred, but carboxyhemoglobin, trichloroethylene, fluorocarbons, and methylene chloride were not elevated in all 17 persons tested; plant-wide monitoring for CO found no elevated levels. During the first outbreak of illness, cases were 2.26 times as likely to have entered the assembly room as noncases. During the second outbreak, cases were no more likely than noncases to have entered the assembly room. We believe the explosion, earlier toxic exposures and illness, and the misleading blood test results led to plant-wide anxiety which culminated in a collective stress reaction and the second outbreak. An open meeting with all employees, informing them of our findings, provided reassurance and no further episodes of illness occurred in this workforce.

Sinks, T.; Kerndt, P.R.; Wallingford, K.M.

1989-08-01

347

Mixed waste chemical compatibility with packaging components  

SciTech Connect

In this paper, a chemical compatibility testing program for packaging of mixed wastes at will be described. We will discuss the choice of four y-radiation doses, four time durations, four temperatures and four waste solutions to simulate the hazardous waste components of mixed wastes for testing materials compatibility of polymers. The selected simulant wastes are (1) an aqueous alkaline mixture of sodium nitrate and sodium nitrite; (2) a chlorinated hydrocarbon mixture; (3) a simulant liquid scintillation fluid; and (4) a mixture of ketones. A selection of 10 polymers with anticipated high resistance to one or more of these types of environments are proposed for testing as potential liner or seal materials. These polymers are butadiene acrylonitrile copolymer, cross-linked polyethylene, epichlorhyarin, ethylene-propylene rubber, fluorocarbon, glass-filled tetrafluoroethylene, high-density poly-ethylene, isobutylene-isoprene copolymer, polypropylene, and styrene-butadiene rubber. We will describe the elements of the testing plan along with a metric for establishing time resistance of the packaging materials to radiation and chemicals.

Nigrey, P.J. [Sandia National Labs., Albuquerque, NM (United States); Conroy, M.; Blalock, L.B. [USDOE, Washington, DC (United States)

1994-05-01

348

NMR at the Picomole Level of a DNA Adduct  

PubMed Central

We investigate the limit of detection for obtaining NMR data of a DNA adduct using modern microscale NMR instrumentation, once the adduct has been isolated at the pmol level. Eighty nanograms (130 pmol) of a DNA adduct standard, N-(2?-deoxyguanosin-8-yl)-2-acetylaminofluorene 5?-monophosphate (AAF-dGMP), in 1.5 ?L of D2O with 10% methanol-d4, in a vial, was completely picked up as a droplet suspended in a fluorocarbon liquid, and loaded efficiently into a microcoil probe. This work demonstrates a practical manual method of droplet microfluidic sample loading, previously demonstrated using automated equipment, which provides a several-fold advantage over conventional flow injection. Eliminating dilution during injection and confining the sample into the observed volume realizes the full theoretical mass sensitivity of a microcoil, comparable to a micro-cryo probe. With 80 ng, an NMR spectrum acquired over 40 hr showed all of the resonances seen in a standard spectrum of AAF-dGMP, with a S/N of at least 10, despite broadening due to previously-noted effects of conformational exchange. Also a 2D TOCSY spectrum (total correlation spectroscopy) was acquired on 1.6 ?g in 18 hr. This work helps to define the utility of NMR in combination with other analytical methods for the structural characterization of a small amount of a DNA adduct. PMID:24028148

Kautz, Roger; Wang, Poguang; Giese, Roger W.

2014-01-01

349

Equipment and design changes in extrusion of foamed fluoropolymer resins  

NASA Astrophysics Data System (ADS)

Recent growth of computer networks has increased the market for foamed coaxial cables. To meet this need, the gas injection process for foaming of Teflon* FEP and PFA fluorocarbon resins introduced in 1981 at the 30th Wire and Cable Symposium has been refined. Advances in die and extruder screw design have broadened capability from 500 CATV coaxial cable to miniature wire sizes. Increased processing speeds and higher core quality have been achieved. These coaxial cables have a unique combination of properties that are maintained over a wide range of temperatures and signal frequencies. They have dielectric constants as low as 1.3 and low flame spread and smoke generation as tested to UL 910. These cables are now widely used for high frequency signal transmission in compliance with the National Electric Code for installation without conduit in building air handling plenums. Military applications represent newer areas of interest with weight and space savings and high electrical quality. The characteristics of several coaxial cables are reviewed.

Randa, S. K.; Carlson, M. A.; Reifschneider, D. P.

350

Direct measurement of surface carbon concentrations. [in lunar soil  

NASA Technical Reports Server (NTRS)

Measurements of surface concentrations of carbon in lunar soils and soil breccias provide information on the origin of carbon in the regolith. The reaction C-12 (d, p sub zero) is used to measure 'surface' and 'volume' concentrations in lunar samples. This method has a depth resolution of 1 micron, which permits only a 'surface' and a 'volume' component to be measured. Three of four Apollo 16 double drive tube samples show a surface carbon concentration of about 8 by 10 to the 14th power/sq cm, whereas the fourth sample gave 4 by 10 to the 14th power/sq cm. It can be convincingly shown that the measured concentration does not originate from fluorocarbon or hydrocarbon contaminants. Surface adsorbed layers of CO or CO2 are removed by a sputter cleaning procedure using a 2-MeV F beam. It is shown that the residual C concentration of 8 by 10 to the 14th power/sq cm cannot be further reduced by increased F fluence, and it is therefore concluded that it is truly lunar. If one assumes that the measured surface C concentration is a steady-state concentration determined only by a balance between solar-wind implantation and sputtering, a sputter erosion rate of 0.1 A/yr is obtained. However, it would be more profitable to use an independently derived sputter erosion rate to test the hypothesis of a solar-wind origin of the surface carbon.

Filleux, C.; Tombrello, T. A.; Burnett, D. S.

1977-01-01

351

Prediction of ultraviolet-induced damage during plasma processes in dielectric films using on-wafer monitoring techniques  

SciTech Connect

We measured electron-hole pairs generated in dielectric film using our developed on-wafer monitoring technique to detect electrical currents in the film during the plasma etching processes. The electron-hole pairs were generated by plasma induced ultraviolet (UV) photons, and the number of electron-hole pairs depends on the UV wavelength. In SiO{sub 2} film, UV light, which has a wavelength of less than 140 nm, generates electron-hole pairs, because the band gap energy of the film is 8.8 eV. On the other hand, in Si{sub 3}N{sub 4} film, which has a band gap energy level of 5.0 eV, UV light below 250 nm induces the electron-hole pairs. Additionally, we evaluated the fluorocarbon gas plasma process that induces UV radiation damage using multilayer sensors that consisted of both SiO{sub 2} and Si{sub 3}N{sub 4} stacked films. In these cases, electron-hole pair generation depended on the dielectric film structure. There were more electron-hole pairs generated in the SiO{sub 2} deposited on the Si{sub 3}N{sub 4} film than in the Si{sub 3}N{sub 4} deposited on the SiO{sub 2} film. As a result, our developed on-wafer monitoring sensor was able to predict electron-hole pair generation and the device characteristics.

Ishikawa, Yasushi; Katoh, Yuji; Okigawa, Mitsuru; Samukawa, Seiji [Intelligent Nano-Process Laboratory, Institute of Fluid Science, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai, 980-8577 (Japan); Intelligent Nano-Process Laboratory, Institute of Fluid Science, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai, 980-8577 Japan and Sanyo Electric Co., Ltd., Component Group, Semiconductor Company, CCD Business Unit, Development Department, 180 Ohmori, Anpachi-cho, Anpachi-gun, Gifu, 503-0195 (Japan); Intelligent Nano-Process Laboratory, Institute of Fluid Science, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai, 980-8577 (Japan)

2005-11-15

352

Mass spectrometry imaging on porous silicon: investigating the distribution of bioactives in marine mollusc tissues.  

PubMed

Desorption/ionization on porous silicon-mass spectrometry (DIOS-MS) is an attractive alternative to conventional matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) for the analysis of low molecular weight compounds. Porous silicon (pSi) chips are also suitable as support for mass spectrometry imaging (MSI). Here, we report an implementation of DIOS-MSI using the biosynthetic organs of a marine mollusc for proof of principle. The tissue section is stamped onto a fluorocarbon-functionalized pSi chip, which extracts and traps small hydrophobic molecules from the tissue under retention of their relative spatial distribution. The section is subsequently removed and the chip is imaged without any remaining tissue. We apply this novel tissue contact printing approach to investigate the distribution of biologically active brominated precursors to Tyrian purple in the hypobranchial gland of the marine mollusc, Dicathais orbita, using DIOS-MSI. The tissue contact printing is also compatible with other types of desorption/ionization surfaces, such as nanoassisted laser desorption/ionization (NALDI) targets. PMID:23009618

Ronci, Maurizio; Rudd, David; Guinan, Taryn; Benkendorff, Kirsten; Voelcker, Nicolas H

2012-11-01

353

Climate change and air pollution jointly creating nightmare for tourism industry.  

PubMed

The objective of the study is to examine the long-run and causal relationship between climate change (i.e., greenhouse gas emissions, hydrofluorocarbons, per fluorocarbons, and sulfur hexafluoride), air pollution (i.e., methane emissions, nitrous oxide emissions, and carbon dioxide emissions), and tourism development indicators (i.e., international tourism receipts, international tourism expenditures, natural resource depletion, and net forest depletion) in the World's largest regions. The aggregate data is used for robust analysis in the South Asia, the Middle East and North Africa, sub-Saharan Africa, and East Asia and the Pacific regions, over a period of 1975-2012. The results show that climatic factors and air pollution have a negative impact on tourism indicators in the form of deforestation and natural resource depletion. The impact is evident, as we have seen the systematic eroding of tourism industry, due to severe changes in climate and increasing strain of air pollution. There are several channels of cause-effect relationship between the climatic factors, air pollution, and tourism indicators in the World's region. The study confirms the unidirectional, bidirectional, and causality independent relationship between climatic factors, air pollution, and tourism indicators in the World. It is conclusive that tourism industry is facing all time bigger challenges of reduce investment, less resources, and minor importance from the government agencies because of the two broad challenges, i.e., climate change and air pollution, putting them in a dismal state. PMID:24938808

Sajjad, Faiza; Noreen, Umara; Zaman, Khalid

2014-11-01

354

Preliminary observations of lung injury produced by instillation of HF in acidic and neutral buffer  

SciTech Connect

Perfluoroisobutylene (PFIB) is an extremely toxic organofluoride that can be produced during pyrolysis of tetrafluoroethylene polymers, including Teflon{reg sign}. Inhalation of PFIB at very low concentrations causes acute lung injury, the hallmark of which is pulmonary edema. Several lines of evidence have suggested that hydrolysis of PFIB and resulting production of hydrofluoric acid may be responsible for pulmonary damage. In order to investigate the potential involvement of hydrofluoric acid in producing lung injury and its relationship to the mechanism of fluorocarbon toxicity, we have compared the pulmonary injury produced by PFIB, by dissociated (H{sup +} and F{sup {minus}}), and by undissociated (HF) hydrofluoric acid in the deep lung. By delivering hydrofluoric acid by intratracheal instillation in neutral buffer, we demonstrate that F{sup {minus}} produces no significant pulmonary injury as assessed by increased in lung weight and ultrastructural changes. Similarly, instillation of acid buffer alone demonstrated that H{sup +} did not produce detectable lung injury. Instillation of HF produced changes in lung weight and ultrastructure similar to those observed in PFIB-treated rats. However, the ultrastructural studies show that in contrast to inhalation of PFIB, which produces both endothelial and epithelial cell damage, instillation of HF appears to exert its injurious effects only upon epithelial cells. 9 refs., 1 fig.

Brainard, J.R.; Kinkead, S.A.; Kober, E.M.; Sebring, R.J.; Stavert, D.M.; Lehnert, B.E.

1990-01-01

355

New concepts for refrigerant leak detection and mixture measurement  

NASA Astrophysics Data System (ADS)

Since the discovery that chlorofluorocarbons (CFC's) destroy the ozone layer, the need to reduce the release of these refrigerants into the environment has become critical. A total ban of ozone-depleting CFC's is expected within a few years, and hydrofluorocarbons (HFC's) and fluorocarbons (FC's) and their mixtures are expected to be used during a transition period. Several HFC and FC refrigerants are currently being considered as CFC substitutes. The electronic refrigerant leak detectors currently being considered as CFC substitutes. The electronic refrigerant leak detectors currently on the market were developed to detect CFC's and are not as sensitive to HFC's. Although incremental improvement can be made to these devices to detect HFC's, they often lead to increased false signals. Also, there is no simple device available to measure the composition of a refrigerant mixture. The authors present two new concepts to aid in the development of two portable instruments that can be used for HFC leak detection and for quantitative measurement of refrigerant mixture compositions. The development of simple, easy-to-use portable leak detectors and refrigerant mixture meters is essential to the wide use of alternative refrigerants in industry.

Chen, F. C.; Allman, S. L.; Chen, C. H.

356

Modeling Surface Water Transport in the Central Pacific Ocean With 129I Records From Coral Skeletons  

NASA Astrophysics Data System (ADS)

129I occurs naturally in extremely low abundance via cosmic ray interactions in the atmosphere as well as by spontaneous fission of uranium. Oceanic concentrations of 129I have risen by several orders of magnitude during the last half century largely from environmental pollution coming from several point-source nuclear fuel reprocessing plants. In the Pacific basin, much of the increase has apparently come from the Hanford Nuclear reprocessing plant in the United States, with iodine primarily arriving via the Columbia River. Coral skeletons preserve records of 129I concentration of the surface waters from which they were deposited, yielding records with annual resolution or better. We will present three such records from different locations in the Pacific Ocean: the Solomon Islands, Easter Island and Clipperton Atoll. For this study, drill cores from living massive coral skeletons of the species Porites Lobata were collected from these sites. 129I/127I values were measured using accelerator mass spectrometry (AMS) at the University of Arizona with an NEC 3 MV Pelletron accelerator. Results from the analysis of the corals will be compared to the distribution of other mixed-layer tracers (chloro-fluorocarbons and tritium) collected during the World Ocean Circulation Experiment cruises conducted between 1990 and 2002. The 129I/127I records observed in these corals will also be compared to tracer transit time calculations determined from a 20th century simulation of the GFDL coupled-climate passive-tracer model.

Beck, W.; Biddulph, D. L.; Russell, J. L.; Burr, G. S.; Jull, T. J.; Correge, T.; Roeder, B.

2008-12-01

357

Modification of TiO? electrode with organic silane interposed layer for high-performance of dye-sensitized solar cells.  

PubMed

Back electron transfer from the TiO2 electrode surface to the electrolyte is the main reason behind the low-open circuit potential (Voc) and the low-fill factor (FF) of the dye-sensitized solar cells (DSSCs). Modifications to the TiO2 electrode, fabricated using {010}-faceted TiO2 nanoparticles with six different kinds of silane, are reported to decrease the back electron transfer on the TiO2 surface. The effect of alkyl chain length of hydrocarbon silanes and fluorocarbon silanes on adsorption parameters of surface coverage and adsorption constant, interfacial resistance, and photovoltaic performances were investigated. Adsorption isotherms, impedance analysis, and photovoltaic measurements were used as the investigation techniques. The reduction of back electron transfer depended on the TiO2 surface coverage by silane, alkyl chain length, and the molecular structure of the silane. Even though Voc and FF were improved, significant reduction in short-circuit photocurrent density (Jsc) was observed after silanization because of desorption of dye during silanization. A new approach, sequential adsorption process of silane and dye, was introduced to enhance Voc and FF without lowering Jsc. Heptadecafluorodecyl trimethoxy-silane showed the highest coverage on the surface of the TiO2 and had the highest effect on the performance improvement of the DSSC, where Voc, FF, and efficiency (?) were improved by 22, 8.0, and 22%, respectively. PMID:24684283

Sewvandi, Galhenage A; Tao, Zhuoqi; Kusunose, Takafumi; Tanaka, Yasuhiro; Nakanishi, Shunsuke; Feng, Qi

2014-04-23

358

Solar silicon via improved and expanded metallurgical silicon technology  

NASA Technical Reports Server (NTRS)

A completed preliminary survey of silica sources indicates that sufficient quantities of high-purity quartz are available in the U.S. and Canada to meet goals. Supply can easily meet demand for this little-sought commodity. Charcoal, as a reductant for silica, can be purified to a sufficient level by high-temperature fluorocarbon treatment and vacuum processing. High-temperature treatment causes partial graphitization which can lead to difficulty in smelting. Smelting of Arkansas quartz and purified charcoal produced kilogram quantities of silicon having impurity levels generally much lower than in MG-Si. Half of the goal was met of increasing the boron resistivity from 0.03 ohm-cm in metallurgical silicon to 0.3 ohm-cm in solar silicon. A cost analysis of the solidification process indicate $3.50-7.25/kg Si for the Czochralski-type process and $1.50-4.25/kg Si for the Bridgman-type technique.

Hunt, L. P.; Dosaj, V. D.; Mccormick, J. R.

1977-01-01

359

Surface-catalyzed air oxidation of hydrazines: Environmental chamber studies  

NASA Technical Reports Server (NTRS)

The surface-catalyzed air oxidation reactions of fuel hydrazines were studied in a 6500-liter fluorocarbon-film chamber at 80 to 100 ppm concentrations. First-order rate constants for the reactions catalyzed by aluminum, water-damaged aluminum (Al/Al2O3), stainless steel 304L, galvanized steel and titanium plates with surface areas of 2 to 24 sq m were determined. With 23.8 sq m of Al/Al2O3 the surface-catalyzed air oxidation of hydrazine had a half-life of 2 hours, diimide (N2H2) was observed as an intermediate and traces of ammonia were present in the final product mixture. The Al/Al2O3 catalyzed oxidation of monomethylhydrazine yielded methyldiazine (HN = NCH3) as an intermediate and traces of methanol. Unsymmetrical dimethylhydrazine gave no detectable products. The relative reactivities of hydrazine, MMH and UDMH were 130 : 7.3 : 1.0, respectively. The rate constants for Al/Al2O3-catalyzed oxidation of hydrazine and MMH were proportional to the square of the surface area of the plates. Mechanisms for the surface-catalyzed oxidation of hydrazine and diimide and the formation of ammonia are proposed.

Kilduff, Jan E.; Davis, Dennis D.; Koontz, Steven L.

1988-01-01

360

Environmental Fate of the Next Generation Refrigerant 2,3,3,3-Tetrafluoropropene (HFO-1234yf).  

PubMed

The hydrofluoroolefin 2,3,3,3-tetrafluoropropene (HFO-1234yf) has been introduced to replace 1,1,1,2-tetrafluoroethane (HFC-134a) as refrigerant in mobile, including vehicle, air conditioning systems because of its lower global warming potential. HFO-1234yf is volatile at ambient temperatures; however, high production volumes and widespread handling are expected to release this fluorocarbon into terrestrial and aquatic environments, including groundwater. Laboratory experiments explored HFO-1234yf degradation by (i) microbial processes under oxic and anoxic conditions, (ii) abiotic processes mediated by reactive mineral phases and zerovalent iron (Fe(0), ZVI), and (iii) cobalamin-catalyzed biomimetic transformation. These investigations demonstrated that HFO-1234yf was recalcitrant to microbial (co)metabolism and no transformation was observed in incubations with ZVI, makinawite (FeS), sulfate green rust (GRSO4), magnetite (Fe3O4), and manganese oxide (MnO2). Sequential reductive defluorination of HFO-1234yf to 3,3,3-trifluoropropene and 3,3-dichloropropene with concomitant stoichiometric release of fluoride occurred in incubations with reduced cobalamins (e.g., vitamin B12) indicating that biomolecules can transform HFO-1234yf at circumneutral pH and at ambient temperature. Taken together, these findings suggest that HFO-1234yf recalcitrance in aquifers should be expected; however, HFO-1234yf is not inert and a biomolecule may mediate reductive transformation in low redox environments, albeit at low rates. PMID:25329364

Im, Jeongdae; Walshe-Langford, Gillian E; Moon, Ji-Won; Löffler, Frank E

2014-11-18

361

Uncertainties in Air Exchange using Continuous-Injection, Long-Term Sampling Tracer-Gas Methods  

SciTech Connect

The PerFluorocarbon Tracer (PFT) method is a low-cost approach commonly used for measuring air exchange in buildings using tracer gases. It is a specific application of the more general Continuous-Injection, Long-Term Sampling (CILTS) method. The technique is widely used but there has been little work on understanding the uncertainties (both precision and bias) associated with its use, particularly given that it is typically deployed by untrained or lightly trained people to minimize experimental costs. In this article we will conduct a first-principles error analysis to estimate the uncertainties and then compare that analysis to CILTS measurements that were over-sampled, through the use of multiple tracers and emitter and sampler distribution patterns, in three houses. We find that the CILTS method can have an overall uncertainty of 10-15percent in ideal circumstances, but that even in highly controlled field experiments done by trained experimenters expected uncertainties are about 20percent. In addition, there are many field conditions (such as open windows) where CILTS is not likely to provide any quantitative data. Even avoiding the worst situations of assumption violations CILTS should be considered as having a something like a ?factor of two? uncertainty for the broad field trials that it is typically used in. We provide guidance on how to deploy CILTS and design the experiment to minimize uncertainties.

Sherman, Max H.; Walker, Iain S.; Lunden, Melissa M.

2013-12-01

362

Facile catalyst separation without water: fluorous biphase hydroformylation of olefins.  

PubMed

A novel concept for performing stoichiometric and catalytic chemical transformations has been developed that is based on the limited miscibility of partially or fully fluorinated compounds with nonfluorinated compounds. A fluorous biphase system (FBS) consists of a fluorous phase containing a dissolved reagent or catalyst and another phase, which could be any common organic or nonorganic solvent with limited or no solubility in the fluorous phase. The fluorous phase is defined as the fluorocarbon (mostly perfluorinated alkanes, ethers, and tertiary amines)-rich phase of a biphase system. An FBS compatible reagent or catalyst contains enough fluorous moieties that it will be soluble only or preferentially in the fluorous phase. The most effective fluorous moieties are linear or branched perfluoroalkyl chains with high carbon number; they may also contain heteroatoms. The chemical transformation may occur either in the fluorous phase or at the interface of the two phases. The application of FBS has been demonstrated for the extraction of rhodium from toluene and for the hydroformylation of olefins. The ability to separate a catalyst or a reagent from the products completely at mild conditions could lead to industrial application of homogeneous catalysts or reagents and to the development of more environmentally benign processes. PMID:17814001

Horváth, I T; Rábai, J

1994-10-01

363

X-ray evaluation of the boundary between polymer electrolyte and platinum and carbon functionalization to conduct protons in polymer electrolyte fuel cells  

NASA Astrophysics Data System (ADS)

In polymer electrolyte fuel cells (PEFCs), it is important to secure proximate diffusion paths of reactants and electrons. One approach is to optimize the boundary between polymer electrolyte and Pt nanoparticle surface. Based on synchrotron X-ray absorption fine structure to monitor directly the status of catalysts in PEFCs, it was found that Pt sites were reduced to Pt0 by alcohols contained in polymer electrolyte dispersion solution during the preparation of cathode of PEFC. As in membrane electrolyte assembly, only the Pt sites not covered by polymer electrolyte re-oxidized to Pt2+/4+. Thus, the interface between Pt and polymer electrolyte was evaluated. The other approach is to functionalize carbon surface with sulfonate/sulfate group to conduct protons. Similar level of proton conductivity was observed in current-voltage dependence compared to using polymer electrolyte, but polymer electrolyte was advantageous to lose less voltage for activation. Based on this comparison, optimum catalyst on cathode is proposed comprising surface sulfonate/sulfate group on carbon mixed with polymer electrolyte. Further optimization of cathode catalyst is proposed to functionalize carbon with sulfonate group linked to fluorocarbon branch.

Oka, Kazuki; Ogura, Yuta; Izumi, Yasuo

2014-07-01

364

A Roof for the Lion's House  

NASA Technical Reports Server (NTRS)

Fans of the National Football League's Detroit Lions don't worry about gameday weather. Their magnificent new Pontiac Stadium has a domed, air-supported, fabric roof that admits light but protects the playing field and patrons from the elements. The 80,000-seat "Silverdome" is the world's largest fabric-covered structure-and aerospace technology played an important part in its construction. The key to economical construction of the Silverdome-and many other types of buildings-is a spinoff of fiber glass Beta yarn coated with Teflon TFE fluorocarbon resin. The big advance it offers is permanency. Fabric structures-tents, for example have been around since the earliest years of human civilization. But their coverings-hides, canvas and more recently plastics-were considered temporary; though tough, these fabrics were subject to weather deterioration. Teflon TFE-coated Beta Fiberglas is virtually impervious to the effects of weather and sunlight and it won't stretch, shrink, mildew or rot, thus has exceptional longevity; it is also very strong, lightweight, flame resistant and requires no periodic cleaning, because dirt will not stick to the surface of Teflon TFE. And to top all that, it costs only 30 to 40 percent as much as conventional roofing.

1978-01-01

365

Toxicology of the fluoroalkenes: Review and research needs  

PubMed Central

In this review of the published literature on the toxicology of fluoroalkenes several features emerge and research needs are evident. The fluoroalkenes vary widely in acute inhalation toxicity. Those, such as perfluoroisobutylene, PFIB, the most highly toxic member, attacks the pulmonary epithelium of rats eventuating in edema and death after a delay of about one day. Other fluoroalkenes, such as hexafluoropropylene (HFP) or chlorotrifluoroethylene (CTFE), also cause pulmonary injury but at lower concentrations produce concentration dependent changes in the renal concentrating mechanism of the rat. Changes in the CNS of rats and rabbits have also been reported for CTFE. CTFE, in repeated exposures, has produced blood pressure changes in dogs, CNS effects and changes in the erythropoietic system. This variety of responses indicates the need for investigation. Chronic effects have not been sufficiently studied for PFIB and HFP. Thus pointing up the desirability for study. Mechanisms of action research for fluoroalkenes is an important area of need. While several ideas have been suggested, there are no data to support them. The nucleophilic sensitivity of the fluoroalkenes and the potential carcinogenic effects stemming therefrom suggests a need field for investigation. We also can readily perceive the needs for the evaluation of effects on reproduction (including mutagenesis and teratogenesis), metabolism pulmonary functions, cellular function and structure. Epidemiologic studies on occupationally exposed populations are desirable in order to adequately define human health hazard from these fluorocarbons. PMID:612451

Clayton, J. Wesley

1977-01-01

366

Soil solution chemistry of sewage-sludge incinerator ash and phosphate fertilizer amended soil  

SciTech Connect

The chemical composition of the soil provides useful information on the feasibility of amending agricultural land with municipal and industrial waste, because the soil solution is the medium for most soil chemical reactions, the mobile phase in soils, and the medium for mineral adsorption by plant roots. The soil solutions studies in this research were from plots in a 4-yr field experiment conducted to evaluate the effects of the trace metals and P in sewage-sludge incinerator ash. Treatments compared ash with equivalent P rates from triple-superphosphate fertilizer and a control receiving no P application. Ash and phosphate fertilizer were applied annually at rates of 35, 70, and 140 kg citrate-soluble P ha{sup -1}. Cumulative ash applications during 4 yr amounted to 3.6, 7.2, and 14.4 Mg ash ha{sup -1}. Soil solutions were obtained by centrifugation-immiscible liquid displacement using a fluorocarbon displacing agent. Following chemical analysis, a chemical speciation model was used to determine possible solubility-controlling minerals for trace metals and P, and correlations between solution composition and plant uptake were analyzed. 37 refs., 5 tabs.

Bierman, P.M.; Rosen, C.J.; Bloom, P.R.; Nater, E.A. [Univ. of Minnesota, St. Paul, MN (United States)

1995-03-01

367

Chain Elongation during Thermolysis of Tetrafluoroethylene and Hexafluoropropylene: Modeling of Mechanistic Hypotheses and Elucidation of Data Needs  

SciTech Connect

Thermolysis of tetrafluoroethylene at 500 oC is well-known to lead to equilibration with octafluorocyclobutane; at 600 oC this mixture forms hexafluoropropylene; and at slightly more forcing conditions the latter is converted to octafluoroisobutylene (and/or octafluoro-2-butene). This chain-elongation behavior contrasts with the familiar cracking of non-fluorinated olefins and the thermodynamic rationale is provided herein. Several mechanisms have been proposed in the literature without a clear choice. Kinetic modeling herein of available product/kinetic data with use of current thermochemical and kinetic parameters supports a key role for difluorocarbene formed from dissociation of tetrafluoroethylene. Arbitrary selection between unfortunately inconsistent available measurements and/or computations of elementary rate constants, with modest adjustments, allowed data matches with either a direct insertion into an olefinic C-F bond or an addition to the olefin to give a 1,3-biradical followed by a 1,2-fluorine shift. In contrast, a 1,2-fluorine shift in the starting olefin to generate a carbene, followed by carbene combination, seems unlikely. However, the modeling was only a limited success, especially for hexafluoropropylene as feed which seems a comparatively inefficient source of difluorocarbene. This highlights the need for improved experimental thermolysis data at low conversion, independent elementary rate constants for key steps, and especially enthalpies of formation of fluorocarbons and their reactive intermediates.

Poutsma, Marvin L [ORNL

2011-01-01

368

Langmuir Probe Measurements in an Inductively Coupled Ar/CF4 Plasmas  

NASA Technical Reports Server (NTRS)

Technological advancement in the microelectronics industry requires an understanding of the physical and chemical processes occurring in plasmas of fluorocarbon gases, such as carbon tetrafluoride (CF4) which is commonly used as an etchant, and their mixtures to optimize various operating parameters. In this paper we report data on electron number density (ne), electron temperature'(Te), electron energy distribution function (EEDF), mean electron energy, ion number density (ni), and plasma potential (Vp) measured by using Langmuir probe in an inductively coupled 13.56 MHz radio frequency plasmas generated in 50%Ar:50%CF4 mixture in the GEC cell. The probe data were recorded at various radial positions providing radial profiles of these plasma parameters at 10-50 mTorr pressures and 200 W and 300 W of RF power. Present measurements indicate that the electron and ion number densities increase with increase in pressure and power. Whereas the plasma potential and electron temperature decrease with increase in pressure, and they weakly depend on RF power. The radial profiles exhibit that the electron and ion number densities and the plasma potential peak at the center of the plasma with an exponential fall away from it, while the electron temperature has a minimum at the center and it increases steadily towards the electrode edge. The EEDFs have a characteristic drop near the low energy end at all pressures and pressures and their shapes represent non-Maxwellian plasma and exhibit more like Druyvesteyn energy distribution.v

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

2000-01-01

369

Surface-initiated ring-opening metathesis polymerization of 5-(perfluorohexyl)norbornene on carbon paper electrodes.  

PubMed

Hydrophobic coatings on carbon paper electrodes are known to provide effective water management, superior gas transfer, and improved mechanical stability of the paper in fuel cell applications. Here, we describe the surface-initiated ring-opening metathesis polymerization (ROMP) of 5-(perfluorohexyl)norbornene (NBF6) to prepare fluorocarbon-rich films on carbon paper substrates that were pre-treated with O(2) plasma. For our reaction scheme, the growth of the pNBF6 films is dependent on the concentration of hydroxyl groups on the carbon paper substrate. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were used to determine the required time for O(2) plasma exposure to saturate the surface with hydroxyl-termini. Complete, conformal pNBF6 films were grown on carbon paper electrodes exposed to O(2) plasma for at least 45 s. These films exhibit hydrophobic and oleophobic surface properties and serve as insulative barriers to the diffusion of aqueous ions to the conductive carbon fibers. PMID:20709328

Faulkner, Christopher J; Payne, P Andrew; Jennings, G Kane

2010-11-01

370

Surface-initiated growth of ionomer films from pt-modified gold electrodes.  

PubMed

The ability to chemically wire ionomer films to electrode surfaces can promote transport near interfaces and impact a host of energy-related applications. Here, we demonstrate proof-of-concept principles for the surface-initiated ring-opening metathesis polymerization (SI-ROMP) of norbornene (NB), 5-butylnorbornene (NBH4), and 5-perfluorobutylnorbornene (NBF4) from Pt-modified gold substrates and the subsequent sulfonation of olefins along the polymer backbones to produce ultrathin sulfonated polymer films. Prior to sulfonation, the films are hydrophobic and exhibit large barriers against ion transport, but sulfonation dramatically reduces the resistance of the films by providing pathways for proton diffusion. Sulfonated films derived from NBF4 and NBH4 yield more anodic potentials for oxygen reduction than those derived from NB or unfunctionalized electrodes. These improvements are consistent with hydrophobic structuring by the fluorocarbon or hydrocarbon side groups to minimize interfacial flooding and generate pathways for enhanced O(2) permeation near the interface. Importantly, we demonstrate that the sulfonated polymer chains remain anchored to the surface during voltammetry for oxygen reduction whereas short-chain thiolates that do not tether polymer are removed from the substrate. This approach, which we extend to unmodified gold electrodes at neutral pH, presents a method of cleaning the ionomer/electrode interface to remove molecular components that may hamper the performance of the electrode. PMID:19637878

Berron, Brad J; Faulkner, Christopher J; Fischer, Remington E; Payne, P Andrew; Jennings, G Kane

2009-11-01

371

Degradation of the materials of construction in Li-ion batteries  

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 spectroscopy was shown to be an effective analytical tool for quantifying and verifying aluminum corrosion behavior. Two fluorocarbon-based coatings were shown to improve the resistance of Al to pitting attack. Detailed x-ray photoelectron spectroscopy (XPS) surface analyses showed that there was very little difference in the films observed after simple immersion in either PC:DEC or EC:DMC electrolytes versus those following electrical cycling. Li and P are the predominant surface species. Finally, environmental cracking of copper can occur at or near the lithium potential and only if specific metallurgical conditions exist (work-hardening and large grain size).

Braithwaite, J.W.; Gonzales, A.; Lucero, S.J. [and others

1997-03-01

372

Computational modeling study of the radial line slot antenna microwave plasma source with comparisons to experiments  

SciTech Connect

The radial line slot antenna plasma source is a high-density microwave plasma source comprising a high electron temperature source region within the plasma skin depth from a coupling window and low electron temperature diffusion region far from the window. The plasma is typically comprised of inert gases like argon and mixtures of halogen or fluorocarbon gases for etching. Following the experimental study of Tian et al.[J. Vac. Sci. Technol. A 24, 1421 (2006)], a two-dimensional computational model is used to describe the essential features of the source. A high density argon plasma is described using the quasi-neutral approximation and coupled to a frequency-domain electromagnetic wave solver to describe the plasma-microwave interactions in the source. The plasma is described using a multispecies plasma chemistry mechanism developed specifically for microwave excitation conditions. The plasma is nonlocal by nature with locations of peak power deposition and peak plasma density being very different. The spatial distribution of microwave power coupling depends on whether the plasma is under- or over-dense and is described well by the model. The model predicts the experimentally observed low-order diffusion mode radial plasma profiles. The trends of spatial profiles of electron density and electron temperature over a wide range of power and pressure conditions compare well with experimental results.

Raja, Laxminarayan L. [Department of Aerospace Engineering and Engineering Mechanics, University of Texas at Austin, Austin, Texas 78712 (United States); Mahadevan, Shankar [Esgee Technologies Inc., 1301 S. Capital of Texas Hwy. Suite B-122, Austin, Texas 78746 (United States); Ventzek, Peter L. G.; Yoshikawa, Jun [Tokyo Electron Ltd., Akasaka Biz Tower, 3-1 Akasaka 5-chome, Minato-ku, Tokyo 107-6325 (Japan)

2013-05-15

373

Nuclear magnetic resonance at the picomole level of a DNA adduct.  

PubMed

We investigate the limit of detection for obtaining NMR data of a DNA adduct using modern microscale NMR instrumentation, once the adduct has been isolated at the picomole level. Eighty nanograms (130 pmol) of a DNA adduct standard, N-(2'-deoxyguanosin-8-yl)-2-acetylaminofluorene 5'-monophosphate (AAF-dGMP), in 1.5 ?L of D?O with 10% methanol-d?, in a vial, was completely picked up as a droplet suspended in a fluorocarbon liquid and loaded efficiently into a microcoil probe. This work demonstrates a practical manual method of droplet microfluidic sample loading, previously demonstrated using automated equipment, which provides a severalfold advantage over conventional flow injection. Eliminating dilution during injection and confining the sample to the observed volume produce the full theoretical mass sensitivity of a microcoil, comparable to that of a microcryo probe. With 80 ng, an NMR spectrum acquired over 40 h showed all of the resonances seen in a standard spectrum of AAF-dGMP, with a signal-to-noise ratio of at least 10, despite broadening due to previously noted effects of conformational exchange. Even with this broadening to 5 Hz, a two-dimensional total correlation spectroscopy spectrum was acquired on 1.6 ?g in 18 h. This work helps to define the utility of NMR in combination with other analytical methods for the structural characterization of a small amount of a DNA adduct. PMID:24028148

Kautz, Roger; Wang, Poguang; Giese, Roger W

2013-10-21

374

A new concept for spatially divided Deep Reactive Ion Etching with ALD-based passivation  

NASA Astrophysics Data System (ADS)

Conventional Deep Reactive Ion Etching (DRIE) is a plasma etch process with alternating half-cycles of 1) Si-etching with SF6 to form gaseous SiFx etch products, and 2) passivation with C4F8 that polymerizes as a protecting fluorocarbon deposit on the sidewalls and bottom of the etched features. In this work we report on a novel alternative and disruptive technology concept of Spatially-divided Deep Reactive Ion Etching, S-DRIE, where the process is converted from the time-divided into the spatially divided regime. The spatial division can be accomplished by inert gas bearing 'curtains' of heights down to ~20 ?m. These curtains confine the reactive gases to individual (often linear) injection slots constructed in a gas injector head. By horizontally moving the substrate back and forth under the head one can realize the alternate exposures to the overall cycle. A second improvement in the spatially divided approach is the replacement of the CVD-based C4F8 passivation steps by ALD-based oxide (e.g. SiO2) deposition cycles. The method can have industrial potential in cost-effective creation of advanced 3D interconnects (TSVs), MEMS manufacturing and advanced patterning, e.g., in nanoscale transistor line edge roughness using Atomic Layer Etching.

Roozeboom, F.; Kniknie, B.; Lankhorst, A. M.; Winands, G.; Knaapen, R.; Smets, M.; Poodt, P.; Dingemans, G.; Keuning, W.; Kessels, W. M. M.

2012-12-01

375

Phagocytosis of a fluorescently labeled perflubron emulsion by a human monocyte cell line.  

PubMed

We hypothesized that fluorocarbon-based lipid emulsions are phagocytosed by monocytes and that many of the in vivo side effects related to the infusion of these particulate emulsions are due to release of cytokines by these monocytes. To clarify whether these emulsions are actually phagocytosed we attempted to measure by flow cytometry the apparent uptake of a fluorescently labeled high-concentration (90%, w/v) perflubron (perfluorooctyl bromide [PFOB]) emulsion by a differentiated human monocyte cell line. A fluorescent chromophore (Zynaxis Cell Science) was used to label the egg yolk phospholipid in a perflubron emulsion. This phospholipid label was used to track the perflubron emulsion during overnight incubation with the human monocyte (THP-1) cell line which had been differentiated, by exposure to PMA, into macrophage-like cells. Our results indicate that after 24 hours of incubation with the labeled perflubron emulsion, 64.9% (+/- 11.0) of differentiated THP-1 cells had cell-associated emulsion (ingested and/or membrane bound) whereas 24.4 (+/- 6.8%) of the control cells had cell-associated emulsion. We speculate that this technique may be a useful method to track the intravascular persistence and extravascular distribution of such emulsions, and that the degree of uptake of the emulsion by macrophages in this assay may correlate with its in vivo half life. PMID:7849925

Smith, D J; Kornbrust, E S; Lane, T A

1994-01-01

376

Solubility enhancement of phenol and phenol derivatives in perfluorooctyl bromide.  

PubMed

Perfluorinated solvents are gaining popularity as pulmonary ventilation fluids, but they suffer from poor solvent quality in concurrent drug delivery applications. The present study examines the use of a hydrophobic solubilizing agent capable of interacting with model drug solutes by hydrogen bonding with the purpose of enhancing solubility in perfluorooctyl bromide (PFOB). A series of solubilizing agents containing a ketone carbonyl to act as a hydrogen bond acceptor and a perfluoroalkyl chain to maintain the solubility of the putative complex in PFOB are investigated. The solubility of phenol in PFOB is enhanced to the greatest extent by 1-(4-perfluorobutyl phenyl)-1-hexanone (III) where the ketone carbonyl is protected from the electron withdrawing effects of the perfluorobutyl chain by a phenyl ring. Experiments with solubilizers lacking the ketone group suggest that pi-pi bond interactions of III with phenol do not significantly enhance solubility. For a series of phenol derivatives, a rank-order correlation exists between the magnitude of solubility enhancement by III, as reflected by the calculated association constants, and the Hammett sigma parameter of the phenols. Because the O-methyl-substituted phenols do not have the ability to hydrogen bond, their solubility is not enhanced by the presence of III. The results of the present study indicate that solubility of model drug hydrogen bond donating compounds can be enhanced in PFOB by the presence of fluorocarbon-soluble hydrogen bond acceptors. PMID:10189271

Williams, T D; Jay, M; Lehmler, H J; Clark, M E; Stalker, D J; Bummer, P M

1998-12-01

377

Atomic layer etching removal of damaged layers in a contact hole for low sheet resistance  

SciTech Connect

A damaged layer remains on silicon substrates after high-aspect-ratio contact (HARC) etching when using a fluorocarbon gas. Atomic layer etching (ALET) is a technique that can be applied to remove the damaged layer of silicon, removing about 1.36 Å per etch cycle. The characteristics of contact damage removal by ALET are investigated and compared with the conventional damage removal technique of low-power CF{sub 4} plasma etching. The low-power CF{sub 4} plasma etching technique not only has inadequate etch depth control, but also introduces secondary damage by implanting impurities about 25 Å into the contact bottom of the silicon surface. However, ALET allows contact damage to be removed effectively without introducing secondary damage to the substrate, and with precision etch depth control at the angstrom scale. When ALET is applied subsequent to low-power CF{sub 4} plasma etching, the fluorine- and carbon-damaged silicon is effectively removed in about 10 cycles. The sheet resistance of HARC etched silicon decreases from 142 to 137 ?/? after using low-power CF{sub 4} plasma etching, and subsequent ALET treatment further decreases the sheet resistance to 129 ?/?, which is close to the reference value of 124 ?/?.

Kim, Jong Kyu; Cho, Sung Il; Lee, Sung Ho [Memory Division Semiconductor Business, Samsung Electronics, San No. 16 Banwol-Ri,Taean-Eup, Hwasung-City, Gyeonggi-Do, 449-711 (Korea, Republic of)] [Memory Division Semiconductor Business, Samsung Electronics, San No. 16 Banwol-Ri,Taean-Eup, Hwasung-City, Gyeonggi-Do, 449-711 (Korea, Republic of); Kim, Chan Kyu; Min, Kyung Suk; Yeom, Geun Young [Department of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, Gyeonggi-Do 440-746 (Korea, Republic of)] [Department of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, Gyeonggi-Do 440-746 (Korea, Republic of)

2013-11-15

378

Discrete elements for 3D microfluidics.  

PubMed

Microfluidic systems are rapidly becoming commonplace tools for high-precision materials synthesis, biochemical sample preparation, and biophysical analysis. Typically, microfluidic systems are constructed in monolithic form by means of microfabrication and, increasingly, by additive techniques. These methods restrict the design and assembly of truly complex systems by placing unnecessary emphasis on complete functional integration of operational elements in a planar environment. Here, we present a solution based on discrete elements that liberates designers to build large-scale microfluidic systems in three dimensions that are modular, diverse, and predictable by simple network analysis techniques. We develop a sample library of standardized components and connectors manufactured using stereolithography. We predict and validate the flow characteristics of these individual components to design and construct a tunable concentration gradient generator with a scalable number of parallel outputs. We show that these systems are rapidly reconfigurable by constructing three variations of a device for generating monodisperse microdroplets in two distinct size regimes and in a high-throughput mode by simple replacement of emulsifier subcircuits. Finally, we demonstrate the capability for active process monitoring by constructing an optical sensing element for detecting water droplets in a fluorocarbon stream and quantifying their size and frequency. By moving away from large-scale integration toward standardized discrete elements, we demonstrate the potential to reduce the practice of designing and assembling complex 3D microfluidic circuits to a methodology comparable to that found in the electronics industry. PMID:25246553

Bhargava, Krisna C; Thompson, Bryant; Malmstadt, Noah

2014-10-21

379

Systemic oxygen delivery by peritoneal perfusion of oxygen microbubbles.  

PubMed

Severe hypoxemia refractory to pulmonary mechanical ventilation remains life-threatening in critically ill patients. Peritoneal ventilation has long been desired for extrapulmonary oxygenation owing to easy access of the peritoneal cavity for catheterization and the relative safety compared to an extracorporeal circuit. Unfortunately, prior attempts involving direct oxygen ventilation or aqueous perfusates of fluorocarbons or hemoglobin carriers have failed, leading many researchers to abandon the method. We attribute these prior failures to limited mass transfer of oxygen to the peritoneum and have designed an oxygen formulation that overcomes this limitation. Using phospholipid-coated oxygen microbubbles (OMBs), we demonstrate 100% survival for rats experiencing acute lung trauma to at least 2 h. In contrast, all untreated rats and rats treated with peritoneal oxygenated saline died within 30 min. For rats treated with OMBs, hemoglobin saturation and heart rate were at normal levels over the 2-h timeframe. Peritoneal oxygenation with OMBs was therefore shown to be safe and effective, and the method requires less equipment and technical expertise than initiating and maintaining an extracorporeal circuit. Further translation of peritoneal oxygenation with OMBs may provide therapy for acute respiratory distress syndrome arising from trauma, sepsis, pneumonia, aspiration, burns and other pulmonary diseases. PMID:24439406

Feshitan, Jameel A; Legband, Nathan D; Borden, Mark A; Terry, Benjamin S

2014-03-01

380

Mass-analyzed CFx+ (x =1,2,3) ion beam study on selectivity of SiO2-to-SiN etching and a-C :F film deposition  

NASA Astrophysics Data System (ADS)

To clarify the origins of high selectivity in SiO2-to-SiN etching in fluorocarbon gas plasma, mass-analyzed CFx+ (x =1,2,3) ions with a definite kinetic energy of 250-2000eV were irradiated on SiN and SiO2 surfaces. Selectivity in SiO2-to-SiN etching varies greatly for different CFx+ ions. For CF3+ ions, the etch yield of SiN is almost the same as that of SiO2, causing poor selectivity. For CF + ions, on the other hand, the etch yield of SiN is much smaller than that of SiO2. An amorphous fluorinated carbon (a-C :F) film grows without any neutral radicals on the SiN surface at energies below 1250eV and on the SiO2 surface at energies below 500eV due to CF + ion irradiation. The difference in threshold energy of a-C :F film deposition causes high selectivity in SiO2-to-SiN etching. Slight etching of substrate films first takes place at the initial stage of deposition, then etching stops, and a homogeneous a-C :F film is grown. Accumulated carbons during the initial etching reaction modify the surface reaction layer, which causes drastic changes in reactions such as etching to "etch stop" and a-C :F film growth.

Yanai, Ken-ichi; Karahashi, Kazuhiro; Ishikawa, Kenji; Nakamura, Moritaka

2005-03-01

381

Forced convection boiling from a non-flush simulated electric chip  

NASA Astrophysics Data System (ADS)

An experimental investigation is undertaken to determine the effect of heated-surface height on forced convecting boiling. An inert fluorocarbon is circulated through a vertical rectangular channel at velocities of 1 to 4 m/s and subcoolings of 20 and 35 C. Results for five surface heights, as measured relative to the flow channel wall, were obtained. These were 0.127 mm recessed, 0.229, 0.457, and 0.635 mm protruded and flush with the flow-channel wall. A reduction in critical heat flux (CHF) occurred at low velocities while an increase occurred at higher velocities for the protruded cases. A reduction of CHF occurred at all velocities for the recessed condition. Additional results in the velocity range of 5-7 m/s are presented for the flush condition. The data show that for velocities greater than 4 m/s, CHF becomes weakly dependent on the Weber number. The weak dependence on Weber number also implies a direct proportionality to velocity and a weak dependence on heated length.

Leland, J. E.; Chow, L. C.

1992-01-01

382

Forced convection boiling from a nonflush simulated electronic chip  

NASA Astrophysics Data System (ADS)

An experimental investigation has been undertaken to determine the effect of heated surface height on forced convective boiling. An inert fluorocarbon, FC-72 (3M Industrial Chemical Products Division) is circulated through a vertical rectangular channel at velocities of 1-4 m/s and subcoolings of 20 and 35 C. Results for five surface heights, as measured relative to the flow channel wall, were obtained. These were 0.127-mm recessed, 0.229-, 0.457-, and 0.635-mm protruded and flush with the flow channel wall. A reduction in critical heat flux (CHF) occurred at low velocities, while an increase occurred at higher velocities for the protruded cases. A reduction of CHF occurred at all velocities for the recessed condition. Additional results in the velocity range of 5-7 m/s are presented for the flush condition. This data shows that for velocities greater than 4 m/s, CHF becomes weakly dependent on the Weber number. Weak dependence on Weber number also implies a direct proportionality to velocity and a weak dependence on heated length.

Leland, J. E.; Chow, L. C.

1993-10-01

383

Conformal encapsulation of three-dimensional, bioresorbable polymeric scaffolds using plasma-enhanced chemical vapor deposition.  

PubMed

Bioresorbable polymers such as poly(?-caprolactone) (PCL) have a multitude of potential biomaterial applications such as controlled-release drug delivery and regenerative tissue engineering. For such biological applications, the fabrication of porous three-dimensional bioresorbable materials with tunable surface chemistry is critical to maximize their surface-to-volume ratio, mimic the extracellular matrix, and increase drug-loading capacity. Here, two different fluorocarbon (FC) precursors (octofluoropropane (C3F8) and hexafluoropropylene oxide (HFPO)) were used to deposit FC films on PCL scaffolds using plasma-enhanced chemical vapor deposition (PECVD). These two coating systems were chosen with the intent of modifying the scaffold surfaces to be bio-nonreactive while maintaining desirable bulk properties of the scaffold. X-ray photoelectron spectroscopy showed high-CF2 content films were deposited on both the exterior and interior of PCL scaffolds and that deposition behavior is PECVD system specific. Scanning electron microscopy data confirmed that FC film deposition yielded conformal rather than blanket coatings as the porous scaffold structure was maintained after plasma treatment. Treated scaffolds seeded with human dermal fibroblasts (HDF) demonstrate that the cells do not attach after 72 h and that the scaffolds are noncytotoxic to HDF. This work demonstrates conformal FC coatings can be deposited on 3D polymeric scaffolds using PECVD to fabricate 3D bio-nonreactive materials. PMID:25247481

Hawker, Morgan J; Pegalajar-Jurado, Adoracion; Fisher, Ellen R

2014-10-21

384

Surface modified nano-patterned SU-8 pillar array optically transparent super-hydrophobic thin film  

NASA Astrophysics Data System (ADS)

We report the fabrication and characterization of a porous nano-patterned SU-8 high aspect ratio pillar array as a transparent super-hydrophobic thin film. A 250 µm thick SU-8 layer was backside exposed through a glass substrate to form an array of high aspect ratio tapered pillars with angles in the range of 3°-5°. The SU-8 pillar array was plasma treated to form nano-porous surfaces, and then subsequently coated with fluorocarbon (FC) or Parylene-C film. Static contact angles and optical transmittance of various surface conditions such as with and without plasma treatment, Parylene-C versus FC, were tested and results were compared. Among various surface treated SU-8 pillar arrays, the plasma-treated nano-porous FC-coated SU-8 pillar array showed the highest static contact angle of 161°. It was found that the optical transmittance at around 530 nm for the nano-porous FC-coated SU-8 pillar array was approximately 65%, while the bare SU-8 film was approximately 95%. These nano-patterned transparent polymer films could be used in various water-repellent applications.

Yoon, Youngsam; Lee, Dong-Weon; Lee, Jeong-Bong

2012-03-01

385

Fluorinated lamellar phases: structural characterisation and use as templates for highly ordered silica materials.  

PubMed

Highly ordered silica was synthesised by using a lamellar phase comprising the anionic fluorinated surfactant sodium perfluorooctanoate and the partially-fluorinated co-surfactant/oil 1H,1H,2H,2H-perfluorooctan-1-ol in water. The phase behaviour of this system was thoroughly analysed, and it was found that even low levels of the alcohol (<0.5 mol%) were sufficient to induce a phase change from normal micelles to a lamellar phase, rationalised as a result of geometric and electrostatic effects. The properties of these phases were compared to their hydrocarbon analogues, demonstrating the unique and valuable properties exhibited by fluorocarbons, directly related with the observed nanostructure. Small-angle neutron scattering was used to analyse the internal structure of the systems, providing information on the inter-lamellar spacing, bilayer thickness and membrane elasticity. The potential for these phases to act as shear-thinning lubricants was assessed using oscillatory rheology, obtaining shear-dependent viscosity along with storage and loss moduli. PMID:24871766

Pottage, Matthew J; Kusuma, Tiara; Grillo, Isabelle; Garvey, Christopher J; Stickland, Anthony D; Tabor, Rico F

2014-07-21

386

Failure analysis of the lithium battery: A study of the header deposit on the cell top and diffusion within the electrode glass seal using nuclear microanalysis and FFTIR spectroscopy  

NASA Technical Reports Server (NTRS)

The Solid Rocket Booster Range Safety System (SRBRSS) uses a lithium/poly-carbon monofluoride primary battery as a source of electrical power. After cell fabrication and activation, some battery cells have shown self discharge. One possible source of this cell discharge has been suggested to be the formation and growth of a conducting crystallized chemical compound across the glass bead insulator, electrically shorting the glass bead to the casing. This laboratory has begun an analysis of this compound, the glass seal holding the cathode into place, and the cell electrolyte, using Fast Fourier Transform Infrared (FFTIR) Analysis, Rutherford Backscattering Spectroscopy (RBS), and Nuclear Reaction Microanalysis. Preliminary measurements have confirmed the existence of lithium, nitrogen, fluorine, and oxygen on a reddish-brown deposit covering parts of the glass seal holding the positive electrode in place. Cells using Li metal electrodes, have many advantages over conventional primary batteries. One principal disadvantage of using Li batteries on a commercial basis would be the environmental impact of the fluorocarbon material. Another would be the relatively high expense of (CF)n.

Hassan, Razi A.

1991-01-01

387

Application of high-speed digital holographic interferometry for the analysis of temperature distributions and velocity fields in subcooled flow boiling  

NASA Astrophysics Data System (ADS)

Holographic interferometry can be used to visualize density fields in fluids, and thus give insight into temperature distributions in flows. A fully digital reconstruction technique for holographic interferograms is presented that allows to create high-speed interferometric recordings and gives time-resolved information about heat transfer processes. The technique can also be used for a sequential (image to image) analysis of the recordings, which offers higher sensitivity and fewer errors due to optical impurities. Experiments are conducted with a vertical flow boiling channel with one heated wall, using a low boiling fluorocarbon as working liquid in regimes of steady-state nucleate boiling at critical heat flux (CHF), steady-state film boiling and CHF transient. Recording frequencies are up to 7,000 fps. The technique is used to analyze boiling processes at different fluid subcoolings with and without added turbulence. The results give enhanced insight into the temperature distributions, effects of different flow inserts and mechanisms of heat transfer in flow boiling at high heat fluxes. Furthermore, a velocimetric application of the technique is presented using cross-correlation for tracing of density gradients both in boiling and unheated flows. This application gives insight to the velocity distributions in the liquid surrounding the vapor layer. The results show good comparison to particle image velocimetry measurements for the same setup.

Bloch, Gregor; Kuczaty, Julian; Sattelmayer, Thomas

2014-02-01

388

Metals fact sheet - samarium  

SciTech Connect

The crustal abundance of samarium is 7 ppm, similar to that of praseodymium and gadolinium. About 50 percent of the total samarium oxide produced worldwide comes from the mining of monazite. Bastnasite accounts for approximately 40 percent of samarium oxide production, and the remaining 10 percent is derived from other rare earth minerals such as xenotime, apatite, loparite, and rare earth clays. Monazite is usually found in alluvial or beach deposits associated with other heavy minerals, typically rutile and zircon, and is recovered by suction dredging or bucket wheel excavation. The heavy minerals are subsequently separated by gravity, magnetic, and/or electrostatic means, and the resulting monazite concentrate undergoes a series of caustic and acid leaching steps to isolate the rare earths. Bastnasite, on the other hand, is a fluorocarbonate associated with igneous intrusions in quartzite or epithermal, fluorite-bearing veins, and is mined by open-pit methods. The ore is beneficiated by flotation, then acid-leached, filtered and calcined to produce a rare earth concentrate. Although a light rare earth, samarium oxide is isolated only after about three stages of solvent extraction, together with heavier oxides of gadolinium, terbium, and yttrium.

NONE

1993-10-01

389

Effect of casting atmosphere on the shear bond strength of a ceramic to Ni-Cr and Ni-Cr-Be alloys.  

PubMed

The success of metal-ceramic restorations depends on an optimal bond between metal and ceramic. This study evaluated the effect of 3 casting atmospheres on the metal-ceramic bond strength (MCBS) of 2 Ni-Cr alloys, with beryllium (Fit Cast V) and without beryllium (Fit Cast SB). Sixty acrylic resin patterns (8 mm long and 5 mm diameter) were obtained using a fluorocarbon resin matrix. Wax was used to refine the surface of acrylic resin patterns that were invested and cast in an induction casting machine under normal, vacuum, and argon atmospheres at a temperature of 1340 degrees C. The castings were divested manually and airborne-particle abraded with 100-microm aluminum-oxide. Ten castings were obtained for each group. The IPS Classic V ceramic was applied (2 mm high and 5 mm diameter). The shear bond strength was tested in a mechanical testing machine with a crosshead speed of 2.0 mm/min. The MCBS data (MPa) were subjected to 2-way analysis of variance (alpha=0.05). There was no statistically significant difference (p>0.05) between the alloys or among the casting atmospheres. Within the limitations of this study, it may be concluded that the presence of beryllium and the casting atmosphere did not interfere in the MCBS of the evaluated metal-ceramic combinations. PMID:19738947

Pagnano, Valéria Oliveira; Esquivel, Marina de Campos; Leal, Mônica Barbosa; Felipucci, Daniela Nair Borges; Bezzon, Osvaldo Luiz

2009-01-01

390

Implementation of Ultrasonic Sensing for High Resolution Measurement of Binary Gas Mixture Fractions  

PubMed Central

We describe an ultrasonic instrument for continuous real-time analysis of the fractional mixture of a binary gas system. The instrument is particularly well suited to measurement of leaks of a high molecular weight gas into a system that is nominally composed of a single gas. Sensitivity < 5 × 10?5 is demonstrated to leaks of octaflouropropane (C3F8) coolant into nitrogen during a long duration (18 month) continuous study. The sensitivity of the described measurement system is shown to depend on the difference in molecular masses of the two gases in the mixture. The impact of temperature and pressure variances on the accuracy of the measurement is analysed. Practical considerations for the implementation and deployment of long term, in situ ultrasonic leak detection systems are also described. Although development of the described systems was motivated by the requirements of an evaporative fluorocarbon cooling system, the instrument is applicable to the detection of leaks of many other gases and to processes requiring continuous knowledge of particular binary gas mixture fractions. PMID:24961217

Bates, Richard; Battistin, Michele; Berry, Stephane; Bitadze, Alexander; Bonneau, Pierre; Bousson, Nicolas; Boyd, George; Bozza, Gennaro; Crespo-Lopez, Olivier; Riva, Enrico Da; Degeorge, Cyril; Deterre, Cecile; DiGirolamo, Beniamino; Doubek, Martin; Favre, Gilles; Godlewski, Jan; Hallewell, Gregory; Hasib, Ahmed; Katunin, Sergey; Langevin, Nicolas; Lombard, Didier; Mathieu, Michel; McMahon, Stephen; Nagai, Koichi; Pearson, Benjamin; Robinson, David; Rossi, Cecilia; Rozanov, Alexandre; Strauss, Michael; Vitek, Michal; Vacek, Vaclav; Zwalinski, Lukasz

2014-01-01

391

Nonfunctionalized Polydimethyl Siloxane Superhydrophobic Surfaces Based on Hydrophobic-Hydrophilic Interactions  

SciTech Connect

Superhydrophobic surfaces based on polydimethyl siloxane (PDMS) were fabricated using a 50:50 PDM-poly(ethylene glycol) (PEG) blend. PDMS was mixed with PEG, and incomplete phase separation yielded a hierarchic structure. The phase-separated mixture was annealed at a temperature close to the crystallization temperature of the PEG. The PEG crystals were formed isothermally at the PDMS/PEG interface, leading to an engineered surface with PDMS spherulites. The resulting roughness of the surface was studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The PDMS spherulites, a few micrometers in diameter observed from SEM images, were found to have an undulated (rippled) surface with nanometer-sized features. The combination of micrometer- and nanometer-sized surface features created a fractal surface and increased the water contact angle (WCA) of PDMS more than 60, resulting in a superhydrophobic PDMS surface with WCA of >160 degrees. The active surface layer for the superhydrophobicity was approximately 100 mu m thick, illustrating that the material had bulk superhydrophobicity compared to conventional fluorocarbon or fluorinated coated rough surfaces. Theoretical analysis of the fractal surface indicates that the constructed surface has a fractal dimension of 2.5, which corresponds to the Apollonian sphere packing.

Polizos, Georgios [Oak Ridge National Laboratory (ORNL); Tuncer, Enis [ORNL; Qiu, Xiaofeng [ORNL; Aytug, Tolga [ORNL; Kidder, Michelle [ORNL; Messman, Jamie M [ORNL; Sauers, Isidor [ORNL

2011-01-01

392

In situ particle generation during reactive ion etching of SiO sub 2  

SciTech Connect

Particulate contamination during IC fabrication is generally acknowledged as a major contributor to yield loss. In particular, plasma processes have the potential for generating copious quantities of process induced particulates. Ideally, in order to effectively control process generated particulate contamination, a fundamental understanding of the particulate generation and transport is essential. Although a considerable amount of effort has been expended to study particles in laboratory apparatus, only a limited amount of work has been performed in production line equipment with production processes. In these experiments, a Drytek Quad Model 480 single wafer etcher was used to etch blanket thermal SiO{sub 2} films on 150 mm substrates in fluorocarbon discharges. The effects of rf power, reactor pressure, and feed gas composition on particle production rates were evaluated. Particles were measured using an HYT downstream particle flux monitor. Surface particle deposition was measured using a Tencor Surfscan 4500, as well as advanced ex situ techniques. Particle morphology and composition were also determined ex situ. Response surface methodology was utilized to determine the process conditions under which particle generation was most pronounced. The use of in situ and ex situ techniques has provided some insight into the mechanisms involved for particle generation and particle dynamics within the plasma during oxide etching.

Resnick, P J [Sandia National Labs., Albuquerque, NM (United States)] [Sandia National Labs., Albuquerque, NM (United States); Anderson, H M [New Mexico Univ., Albuquerque, NM (United States). Dept. of Chemical and Nuclear Engineering] [New Mexico Univ., Albuquerque, NM (United States). Dept. of Chemical and Nuclear Engineering

1992-01-01

393

Microwave Studies of Perfluoropentane and its Helicity  

NASA Astrophysics Data System (ADS)

Unlike hydrocarbons, fluorocarbons are helical in their all-trans most stable conformations. A definitive experimental determination of the helical angle has not been accomplished because single crystal X-ray studies are not available due to the lack of suitable crystallization solvents, but a value of 17^° from exactly trans is generally accepted from X-ray fiber studies. Using a pulsed-jet Fourier Transform microwave spectrometer, we have observed and assigned the rotational spectra of the lowest energy all-anti C_2 symmetry form of perfluoro-n-pentane and all three of its ^{13}C isotopomers. A, B, and C values of the parent species are 990.6394(4) MHz, 314.00020(14) MHz, and 304.37034(14) MHz, respectively. A range of effective r_0 structures incorporating various model constraints are consistent with about 16^° torsion and a Kraitchman analysis of the parent and ^{13}C species gives 13.3^°. Ab initio calculations are consistent with the experimental results.

Fournier, Joseph A.; Bohn, Robert K.; Montgomery, John A.; , Jr.

2009-06-01

394

Uniform metal nanoparticles produced at high yield in dense microemulsions.  

PubMed

This article demonstrates that bicontinuous microemulsions are optimal templates for high yield production of metal nanoparticles. We have verified this for a variety of microemulsion systems having AOT (sodium bis (2-ethyhexyl) sulphosuccinate) or a fluorocarbon (perfluoro (4-methyl-3,6-dioxaoctane)sulphonate) as surfactant mixed with water and oils like n-heptane or n-dodecane. Several types of metal nanoparticles, including platinum, gold and iron, were produced in these microemulsions having a size range spanning 1.8-17 nm with a very narrow size distribution of ±1 nm. Remarkably high mass concentrations up to 3% were reached. Size and concentration of the nanoparticles could be varied with the stoichiometries of the reagents that constituted them. The optimization towards high yield while maintaining low size polydispersity is due to the decoupling of the time scales for the precipitation reaction and for coarsening. In actual fact, coalescence is essentially prevented by the immobilization of nanoparticles within the bicontinuous microemulsion structure. PMID:22305574

Kowlgi, Krishna; Lafont, Ugo; Rappolt, Michael; Koper, Ger

2012-04-15

395

Microenvironmental nonideality effects in adsorption of surfactants and micellar solubilization  

SciTech Connect

The adsorption tendencies of fluorinated and hydrocarbon chain surfactants at the graphon-water interface were investigated. At low concentrations the affinity of sodium perfluoro-octandate was substantially lower than that of sodium decyl sulfate, a finding consistent with the general weakness of interaction between fluorocarbons and hydrocarbons. The unusual shape of the sodium perfluoro-octanoate isotherm was noted to be in reasonable agreement with several model isotherms that consider both electric and chain-chain interactions of a moderately cooperative nature. The adsorption isotherm of sodium dodecyl sulfate on graphon was biphasic and could not be explained using monolayer models. The formation of a bilayer, after completion of a strongly adsorbed primary layer of surfactant molecules in a roughly parallel orientation, was given as a possible explanation of the observed isotherm. Adsorption data for sodium decyl sulfate, sodium perfluoro-octanoate, and sodium dodecyl sulfate obtained in the presence and absence of sodium chloride were found to define unique isotherms when plotted against the mean ionic activity of the surfactants.

Pyter, R.A.

1980-01-01

396

A comparative study of micellization with fluorinated and hydrogenated diquaternary ammonium bolaamphiphiles.  

PubMed

Two new N(a),N(b)-Bis[3-(trimethylamino)propyl]-perfluoroalkanes diamide-Iodide with (a=1; b=10) and (a=1; b=12), differing by the fluorocarbon tail spacer (8 or 10 CF2), and the N(1),N(12)-Bis[3-(trimethylamino)propyl]-dodecanediamide-Iodide have been synthesized in two steps involving the appropriate dimethyl perfluoro or hydrogeno alkane dicarboxylate, N,N-dimethyl-1,3-propane diamine, and methyl iodide. Their surface properties were studied at 45°C in aqueous solutions using conductivity, surface tension, and dynamic light scattering (DLS) measurements. A comparison of the micellar parameters usually obtained by these techniques has been carried out. The critical micelle concentrations (CMCs), the geometric packing parameters, the surface excess concentration, the area/surfactant molecule at the interface, the micellar ionization degree ? and the free energies of micellization, the diffusion coefficient, and the hydrodynamic diameter were discussed. The effect of added KI on these parameters and on the size and on the kind of aggregates has been also investigated. The addition of 1,2-Dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) to the surfactant solutions, where the size of the complex DOPE-surfactant was determined by DLS over a wide range of concentrations, reveals a very different behavior comparing fluorinated and hydrogenated compounds. PMID:23570869

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

2013-06-15

397

Surface microstructuring of transparent materials by laser-induced backside wet etching using excimer laser  

NASA Astrophysics Data System (ADS)

Silica glass is an important material in optics and optoelectronics because of its outstanding properties, such as transparence in a wide wavelength range, strong damage resistance for laser irradiation, and high chemical stability. In order to develop simpler processes of micro-fabricating silica glass using a pulsed laser, we have investigated a one-step method to microfabricate a silica glass plate using laser-induced backside wet etching (LIBWE) upon irradiation with a ns-pulsed excimer laser. Our idea of LIBWE is based on the deposition of laser energy on the surface of silica glass using ablation of a dye solution. When the dye solution was ablated upon the laser irradiation, the etching of a surface layer was performed on the silica glass. We have succeeded in the micro-fabrication of such transparent materials as silica glass, quartz, calcium fluoride, sapphire and fluorocarbon resin. The advantages of our LIBWE method are as follows, (1) a lwo laser fluence and constant etch rate, (2) microfabrication without debris and cracks formation, (3) large area irradiation with an excimer laser beam through a mask projection, (4) simple pre/post-treatment on target substrates. This is a one-step process simpler method at ambient pressure, which would be used for mass production.

Niino, Hiroyuki; Ding, Ximing; Kurosaki, Ryozo; Narazaki, Aiko; Sato, Tadatake; Kawaguchi, Yoshizo

2003-11-01

398

Study and development of a cryogenic heat exchanger for life support systems  

NASA Technical Reports Server (NTRS)

A prototype cryogenic heat exchanger for removal of waste heat from a spacecraft environmental control life support system was developed. The heat exchanger uses the heat sink capabilities of the cryogenic propellants and, hence, can operate over all mission phases from prelaunch to orbit, to post landing, with quiescent periods during orbit. A survey of candidate warm fluids resulted in the selection of E-2, a fluorocarbon compound, because of its low freezing point and high boiling point. The final design and testing of the heat exchanger was carried out, however, using Freon-21, which is similar to E-2 except for its low boiling point. This change was motivated by the desire for cost effectiveness of the experimental program. The transient performance of the heat exchanger was demonstrated by an analog simulation of the heat sink system. Under the realistic transient heat load conditions (20 sec ramp from minimum to maximum Freon-21 inlet temperature), the control system was able to maintain the warm fluid outlet temperature within + or - 3 F. For a 20-sec ramp from 0 F to -400 F in the hydrogen inlet temperature, at maximum heat load, the warm fluid outlet temperature was maintained within + or - 7 F.

Soliman, M. M.

1973-01-01

399

A Roof for the Lions' House  

NASA Technical Reports Server (NTRS)

Fans of the National Football League s Detroit Lions don't worry about game day weather. Their magnificent new Pontiac Stadium has a domed, air-supported, fabric roof that admits light but protects the playing field and patrons from the elements. The 80,000-seat Silverdome is the world s largest fabric-covered structure-and aerospace technology played an important part in its construction. The key to economical construction of the Silverdome--and many other types of buildings--is a spinoff of fiber glass Beta yarn coated with Teflon TFE fluorocarbon resin. The big advance it offers is permanency.The team of DuPont, Chemical Fabrics and Birdair have collaborated on a number of fabric structures. Some are supported by air pressure, others by cables alone. Most of the structures are in the recreational category. With conventional construction costs still on the upswing, you're likely to see a great many more permanent facilities enclosed by the aerospace spinoff fabric.

1978-01-01

400

Superior performance of multilayered fluoropolymer films in low voltage electrowetting  

E-print Network

The requirement for low operational voltage in electrowetting devices, met using thin dielectrics, is usually connected with serious material failure issues. Dielectric breakdown (visible as electrolysis) is frequently evident slightly beyond the onset of the contact angle saturation. Here, plasma enhanced chemical vapor deposition (PECVD) is used to deposit thin fluorocarbon films prior to the spin-coating of Teflon\\textregistered amorphous fluoropolymer on tetraethoxysilane (TEOS) substrates. The resulting multilayered hydrophobic top coating improves the electrowetting performance of the stack, by showing high resistance to dielectric breakdown at high applied voltages and for continuous long term application of DC and AC voltage. Leakage current measurements during electrowetting experiments with the proposed composite coating showed that current remains fairly constant at consecutive electrowetting tests in contrast to plain Teflon\\textregistered coating in which material degradation is evident by a progressive increase of the leakage current after multiple electrowetting tests. Since the proposed composite coating demonstrates increased resistance to material failure and to dielectric breakdown even at thin configurations, its integration in electrowetting devices may impact their reliability, robustness and lifetime.

Dimitrios P. Papageorgiou; Angeliki Tserepi; Andreas G. Boudouvis; Athanasios G. Papathanasiou

2011-10-18

401

Interplay between mechanical, electrical, and thermal relaxations in nanocomposite proton conducting membranes based on Nafion and a [(ZrO2)·(Ta2O5)(0.119)] core-shell nanofiller.  

PubMed

The thermal, mechanical, and electric properties of hybrid membranes based on Nafion that contain a [(ZrO(2))·(Ta(2)O(5))(0.119)] "core-shell" nanofiller are elucidated. DSC investigations reveal the presence of four endothermic transitions between 50 and 300 °C. The DMA results indicate improved mechanical stability of the hybrid materials. The DSC and DMA results are consistent with our previous suggestion of dynamic R-SO(3)H···[ZrTa] cross-links in the material. These increase the thermal stability of the -SO(3)H groups and the temperature of thermal relaxation events occurring in hydrophobic domains of Nafion. The broadband electrical spectroscopic analysis reveals two electric relaxations associated with the material's interfacial (?(IP)) and bulk proton conductivities (?(EP)). The wet [Nafion/(ZrTa)(1.042)] membrane has a conductivity of 7.0 × 10(-2) S cm(-1) at 115 °C, while Nafion has a conductivity of 3.3 × 10(-2) S cm(-1) at the same temperature and humidification conditions. ?(EP) shows VTF behavior, suggesting that the long-range conductivity is closely related to the segmental motion of the Nafion host matrix. Long-range conduction (?(EP)) occurs when the dynamics of the fluorocarbon matrix induces contact between different delocalization bodies (DB), which results in proton exchange processes between these DBs. PMID:23102554

Di Noto, Vito; Piga, Matteo; Giffin, Guinevere A; Vezzù, Keti; Zawodzinski, Thomas A

2012-11-21

402

Part 1. Approaches to the total synthesis of the diterpene marrubin. Part II. Ligand assisted nucleophilic additions. Part III. Coal processing in a non-dissolving medium  

SciTech Connect

The total synthesis of the diterpene marrubiin was attempted using methodology previously developed in the Liotta laboratories. Ligand Assisted Nucleophilic Additions (LANA) comprise a new class of synthetic reactions involving the stereoselective addition of some group, usually in an intramolecular conjugate fashion. This group is itself derived from an earlier nucleophilic addition to a carbonyl moiety. Exchange of the original metal of the alkoxide with a second metal (which must be at least divalent) having a transferrable group demands that the stereochemistry of the first addition control the second. The general features of these types of processes are discussed. Initial work with substituted quinones is presented, and some mechanistic rationales are given. A novel method of coal processing at modest temperatures and hydrogen pressures (250-300/sup 0/C, 8.0 MPa) is discussed. Coals reacted with small amounts of tetrahydroquinoline in the presence of fluorocarbons or other non-dissolving media underwent astounding increases in pyridine solubility, a common standard in coal liquefaction studies. Several additives were employed, although only tetrahydroquinoline was found to effectively increase coal solubility. Coals having vastly different individual properties behaved similarly under these conditions. Kinetic and model studies were used in an attempt to clarify the reactions occurring under these novel conditions.

Lipscombe, J.; Charles, W. II

1987-01-01

403

Analysis of structure-cytotoxicity in vitro relationship (SAR) for perfluorinated carboxylic acids.  

PubMed

Perfluorinated carboxylic acids (PFAs) represent derivatives of naturally occurring compounds and have been widely used in various industrial fields for decades. They are known to be environmentally persistent. Thus far numerous reports have been focused on reproductive toxicity of PFAs in animals but few studies have been carried out on toxicity towards human cells. Viability tests were performed here at varying time-exposures on C6-C18 PFAs with human colon carcinoma (HCT116) cells. These cells were found earlier as the most useful line for in vitro assays. A chain length-EC50 dependence has been clearly observed. Estimated values of EC50 decreased with elongation of fluorocarbon chain (PFHxA > PFHpA > PFOA > PFNA > PFDA > PFDoA > PFTeDA). Further elongation (C16 and C18) did not deepen the effect but even partially reversed it. The effect was intensified after longer exposure (72 h); at relatively low 40 microM PFTeDA, the viability decreased to approximately 50%. It seems that PFAs are not acutely toxic at the cellular level. Even so, however, they can trigger cell apoptosis, which is prominent in the case of myristic acid perfluorinated analogue. PMID:17572060

Kleszczy?ski, Konrad; Gardzielewski, Pawe?; Mulkiewicz, Ewa; Stepnowski, Piotr; Sk?adanowski, Andrzej C

2007-09-01

404

Is there any chlorine monoxide in the stratosphere?  

NASA Technical Reports Server (NTRS)

A ground based search for the 856.50137/cm R(9.5) and for the 859.76765 R(12.5) transitions of stratospheric (Cl-35)O was made in the solar absorption mode using an infrared heterodyne spectrometer. Lines due to stratospheric HNO3 and tropospheric OCS were detected, at about 0.3% absorption levels. The expected lines of ClO in this same region were not detected, even though the optical depth of the ClO lines should be on the order of 0.2% using currently accepted ClO abundances. These infrared measurements suggest that stratospheric ClO is at least a factor of 7 less abundant than is indicated by indirect in situ fluorescence measurements, and the upper limit of 2.4x10 to the 13th power molecules/sq cm to the integrated column density of ClO is a factor of over 4 less than is indicted by microwave measurements. Results imply that the release of fluorocarbon precursors of ClO may be significantly less important for the destruction of stratospheric ozone than was previously thought.

Rogers, J. D.; Mumma, M. J.; Kostiuk, T.; Deming, D.; Hillman, J. J.; Faris, J.; Zipoy, D.

1982-01-01

405

Positive Ions in RF Discharge Plasmas of C4F8/Ar and C4F8/O2 Mixtures  

NASA Astrophysics Data System (ADS)

Discharge plasmas of C4F8/Ar and C4F8/O2 mixtures were investigated at a frequency of 13.56 MHz and a power of 34 W and at a pressure of 50 mTorr. Discharge-sustaining voltages vary almost monotonically with the gas mixing ratio. The major positive ions in C4F8/Ar discharge are C2F4+, CF3+ and Ar+. The ion count ratio of CF+ is the most intense among the positive ions in the CF system at a large Ar mixing ratio. From the variations of the ion count ratio of CFx+ (x=0 3), these ions seem to be produced partly by the electron-impact ionization of radicals generated from fluorocarbon films. In C4F8/O2 discharge, the major positive ions are C2F4+, CF3+, CO+ and O2+. The intensity ratios of ionic species vary as a function of gas mixing ratio. The ion count ratio of CO+, COF+ and COF2+ reach a maximum at an O2 mixing ratio of about 50%, and the ion count ratio of CO+ is much higher than that of O2+. This seems to suggest some secondary collision processes that occur in the discharge plasma.

Hirose, Yuji; Ishikawa, Itsuo; Sasaki, Shinya; Nagaseki, Kazuya; Saito, Yukinori; Suganomata, Shinji

1998-10-01

406

Role of C2F4, CF2, and ions in C4F8/Ar plasma discharges under active oxide etch conditions in an inductively coupled GEC cell reactor  

NASA Astrophysics Data System (ADS)

Utilizing infrared diode-laser absorption spectroscopy (IRDLAS) and UV-Visible absorption spectroscopy (UV-Vis), we show that it is possible to make a near complete mass balance of etch reactants and products in a GEC inductively coupled fluorocarbon discharge while actively etching SiO2 substrates. Langmuir probe measurements were performed to measure the total ion current density. C2F4 and CF2 are shown to be the main dissociation products in a C4F8 plasma discharge. The C2F4 concentration decreases as the SiO2 etching rate increases, along with CF2 and CF radicals, suggesting a role in the SiO2 etching process. The addition of Ar to the C4F8 discharge increased the ion flux at the wafer surface, and the consumption rate of C2F4 relative to CF2. The increased ion flux enhanced the SiO2 etching rate, until at a very high degree of Ar dilution of C4F8/Ar the etching rate became neutral limited. We also monitored SiF2 using UV-Vis absorption and CO by IRDLAS. In our work we found SiF2 and CO to be the prevalent Si and C gas phase etch products for the SiO2 etching process.

Barela, Marcos J.; Anderson, Harold M.; Oehrlein, Gottlieb S.

2005-05-01

407

Electron Scattering from Plasma Processing Gases: C2F4 and c-C4F8  

NASA Astrophysics Data System (ADS)

Fluorocarbons like C_2F4 and C_4F8 are very common processing gases in the plasma etching of silicon dioxide, which is an important step in the manufacture of semiconductor microelectronics. Understanding the reaction chemistry of these molecules is crucial for achieving production efficiency and stability of the etched surfaces. In order to explain, and model, the complex collision processes in such low temperature plasmas, a good knowledge of the absolute cross sections for these processes is essential. We have measured elastic and inelastic (vibrational excitation) electron scattering from C_2F4 and C_4F8 using a crossed electron-molecule beam apparatus. The experimental results consist of absolute differential, integral and momentum transfer cross sections in the energy range 1.5-20 eV and angular range 10^o-130^o. In order to investigate the role of intermediate negative ions (resonances) in the scattering process we have also measured excitation functions for elastic scattering and vibrational excitation of the ground electronic state of both molecules. These results are compared with recent theoretical calculations and the limited amount of experimental data available in the literature.

Jelisavcic, Milica; Panajotovic, Radmila; Buckman, Stephen

2004-09-01

408

Theoretical computation of thermophysical properties of high-temperature F2, CF4, C2F2, C2F4, C2F6, C3F6 and C3F8 plasmas  

NASA Astrophysics Data System (ADS)

The calculated values of thermodynamic and transport properties of pure F2 and fluorocarbon compounds CF4, C2F2, C2F4, C2F6, C3F6 and C3F8 at high temperatures are presented in this paper. The thermodynamic properties are determined by the method of Gibbs free energy minimization, using standard thermodynamic tables. The transport properties, including electron diffusion coefficients, viscosity, thermal conductivity and electrical conductivity, are evaluated using the Chapman-Enskog method expanded up to the third-order approximation (second order for viscosity). The most accurate cross-section data that could be located are used to evaluate collision integrals. The calculations based on the assumption of local thermodynamic equilibrium are performed for atmospheric-pressure plasmas in the temperature range from 300 to 30?000 K for different pressures between 0.1 and 10 atm. The results of F2, CF4, C2F2, C2F4 and C2F6 are compared with those of previously published studies. Larger discrepancies occur for transport coefficients; these are explained in terms of the different values of the collision integrals that were used. The results presented here are expected to be more accurate because of the improved collision integrals employed.

Wang, WeiZong; Wu, Yi; Rong, MingZhe; Éhn, László; ?ernušák, Ivan

2012-07-01

409

Precision expansion cloud chamber for homogeneous nucleation studies  

NASA Astrophysics Data System (ADS)

The author describes an expansion cloud chamber for the study of the nucleation of a single component vapor (homogeneous nucleation). The design draws on the many years of experience in this Center in construction of chambers for homogeneous nucleation of water. Design features of the chamber are: exact control of temperature (±0.03 ° C), pressure (±0.5 mm Hg), and automatic control of cycling. Construction features are: all construction materials are stainless steel, glass, or fluorocarbon plastics; the piston seal is a very flexible welded stainless steel bellows; the chamber can be made very clean by heating under vacuum and it is compatible with many substances, e.g., ethanol, nonane, and toluene. Performance features are: excellent repeatability of the expansion cycle over a temperature range of 45° to —15 °C and in day to day operation. Safety features are: automatic detection and warning and inerting against fire and explosion from combustible vapor in the chamber enclosure. The determination of the gas temperature at the maximum expansion is discussed as well as the importance of the ''fast'' pulse technique for the measurement of high nucleation rates.

Schmitt, John L.

1981-11-01

410

Polymerization in emulsion microdroplet reactors  

NASA Astrophysics Data System (ADS)

The goal of this research project is to utilize emulsion droplets as chemical reactors for execution of complex polymerization chemistries to develop unique and functional particle materials. Emulsions are dispersions of immiscible fluids where one fluid usually exists in the form of drops. Not surprisingly, if a liquid-to-solid chemical reaction proceeds to completion within these drops, the resultant solid particles will possess the shape and relative size distribution of the drops. The two immiscible liquid phases required for emulsion polymerization provide unique and complex chemical and physical environments suitable for the engineering of novel materials. The development of novel non-ionic fluorosurfactants allows fluorocarbon oils to be used as the continuous phase in a water-free emulsion. Such emulsions enable the encapsulation of almost any hydrocarbon compound in droplets that may be used as separate compartments for water-sensitive syntheses. Here, we exemplify the promise of this approach by suspension polymerization of polyurethanes (PU), in which the liquid precursor is emulsified into droplets that are then converted 1:1 into polymer particles. The stability of the droplets against coalescence upon removal of the continuous phase by evaporation confirms the formation of solid PU particles. These results prove that the water-free environment of fluorocarbon based emulsions enables high conversion. We produce monodisperse, cross-linked, and fluorescently labeled PU-latexes with controllable mesh size through microfluidic emulsification in a simple one-step process. A novel method for the fabrication of monodisperse mesoporous silica particles is presented. It is based on the formation of well-defined equally sized emulsion droplets using a microfluidic approach. The droplets contain the silica precursor/surfactant solution and are suspended in hexadecane as the continuous oil phase. The solvent is then expelled from the droplets, leading to concentration and micellization of the surfactant. At the same time, the silica solidifies around the surfactant structures, forming equally sized mesoporous particles. The procedure can be tuned to produce well-separated particles or alternatively particles that are linked together. The latter allows us to create 2D or 3D structures with hierarchical porosity. Oil, water, and surfactant liquid mixtures exhibit very complex phase behavior. Depending on the conditions, such mixtures give rise to highly organized structures. A proper selection of the type and concentration of surfactants determines the structuring at the nanoscale level. In this work, we show that hierarchically bimodal nanoporous structures can be obtained by templating silica microparticles with a specially designed surfactant micelle/microemulsion mixture. Tuning the phase state by adjusting the surfactant composition and concentration allows for the controlled design of a system where microemulsion droplets coexist with smaller surfactant micellar structures. The microemulsion droplet and micellar dimensions determine the two types of pore sizes (single nanometers and tens of nanometers). We also demonstrate the fabrication of carbon and carbon/platinum replicas of the silica microspheres using a "lost-wax" approach. Such particles have great potential for the design of electrocatalysts for fuel cells, chromatography separations, and other applications. It was determined that slight variations in microemulsion mixture components (electrolyte concentration, wt% of surfactants, oil to sol ratio, etc.) produces strikingly different pore morphologies and particle surface areas. Control over the size and structure of the smaller micelle-templated pores was made possible by varying the length of the hydrocarbon block within the trimethyl ammonium bromide surfactant and characterized using X-ray diffraction. The effect of emulsion aging was studied by synthesizing particles at progressive time levels from a sample emulsion. It was discovered surface pore size increases after just a few hours, with

Carroll, Nick J.

411

X-ray crystallography and mineral chemistry of bastnaesite from Kanigiri granite, Prakasam district, Andhra Pradesh, India  

NASA Astrophysics Data System (ADS)

The authors report the results of X-ray diffraction (XRD) and geochemical studies on bastnaesites (lanthanum cerium fluoro-carbonate) hosted in alkali Kanigiri Granite of the Prakasam district in Andhra Pradesh, India. The XRD pattern of the investigated bastnaesite displays sharply-defined reflections. The observed d-spacings of the bastnaesite are in very close agreement with those published for bastnaesite standard in International Centre for Diffraction Data (ICDD) Card No. 11-340. The calculated unit cell parameters ( a o ; c o ) and unit cell volume (V) of the studied bastnaesite ( a o 7.1301-7.1413 Å, c o 9.7643-9.7902Å and V 429.8940-432.3875 Å3) are almost equal to values published for bastnaesite standard ( c o 7.1290 Å, c o 9.7744 Å and V 430.19 Å3) in the relevant data card. Geochemical data of bastnaesite reveals high content of Ce (mean 27.22%) followed by La (mean 16.82%), Nd (mean 6.12%) and Pr (mean 1.91%). Compared to light REE (LREE) content (mean 437165 ppm), heavy REE (HREE) content (mean 5867 ppm) is drastically low, with unusually high LREE/HREE ratio (mean 80). The chondrite-normalised plot also exhibits drastic enrichment of LREE relative to HREE with pronounced negative Euanomaly (mean Eu/Eu* = 0.15). High (LREE) N / (HREE) N , (La/Lu) N , (La/Yb) N and (Ce/Yb) N ratios reveal higher fractionation of LREE relative to HREE. The rare earth element (REE) contents of the studied bastnaesite are very close to REE contents of bastnaesite hosted in alkali syenite from Madagascar. The presence of bastnaesite in Kanigiri Granite and soils derived from it enhances the scope of further exploration for bastnaesite in several bodies of alkaline rocks and alkali granitoids present along the eastern margins of the Cuddapah basin, Andhra Pradesh.

Singh, Yamuna; Nagendra Babu, G.; Viswanathan, R.; Sai Baba, M.; Rai, A. K.; Parihar, P. S.

2014-12-01

412

Energy and global climate change: Why ORNL?  

SciTech Connect

Subtle signs of global warming have been detected in studies of the climate record of the past century after figuring in the cooling effects of sulfur emissions from volcanoes and human sources. According to the December 1995 report of the Intergovernment Panel on Climate Change (IPCC), the earth`s surface temperature has increased by about 0.2{degrees}C per decade since 1975. the panel projects about a 2{degrees} increase in global temperature by 2100. The IPCC report states that pollutants-greenhouse gases such as carbon dioxide and fluorocarbons that warm the globe and sulfur emission that cool it-are responsible for recent patterns of climate change. {open_quotes}The balance of evidence,{close_quotes} states the report, {open_quotes}suggests that there is a discrenible human influence on global climate.{close_quotes} This human influence stems largely from fossil fuel combustion, cement production, and the burning of forests, and could intensify as populations grow and developing countries increase energy production and industrial development. The two facts have caught the attention of the news media and public. First, 1995 was declared the hottest year in the 140-year-long record of reliable global measurements. Second, recent years have been marked by an unusually high number of extreme weather events, such as hurricanes, blizzards, and floods. In the 1990`s the world has become more aware of the prospect and possible impacts of global climate change. In the late 1950`s, global climate change was an unknown threat to the world`s environment and social systems. Except for a few ORNL researchers who had just completed their first briefing to the U.S. Atomic Energy Commission on the need to understand the global carbon cycle, the connection between rising carbon dioxide concentrations and potential changes in global climate was not common knowledge, nor were the consequences of climate change understood.

Farrell, M.P.

1995-12-31

413

Reductive degradation of perfluoroalkyl compounds with aquated electrons generated from iodide photolysis at 254 nm.  

PubMed

The perfluoroalkyl compounds (PFCs), perfluoroalkyl sulfonates (PFXS) and perfluoroalkyl carboxylates (PFXA) are environmentally persistent and recalcitrant towards most conventional water treatment technologies. Here, we complete an in depth examination of the UV-254 nm production of aquated electrons during iodide photolysis for the reductive defluorination of six aquated perfluoroalkyl compounds (PFCs) of various headgroup and perfluorocarbon tail length. Cyclic voltammograms (CV) show that a potential of +2.0 V (vs. NHE) is required to induce PFC oxidation and -1.0 V is required to induce PFC reduction indicating that PFC reduction is the thermodynamically preferred process. However, PFCs are observed to degrade faster during UV(254 nm)/persulfate (S(2)O(8)(2-)) photolysis yielding sulfate radicals (E° = +2.4 V) as compared to UV(254 nm)/iodide (I(-)) photolysis yielding aquated electrons (E° = -2.9 V). Aquated electron scavenging by photoproduced triiodide (I(3)(-)), which achieved a steady-state concentration proportional to [PFOS](0), reduces the efficacy of the UV/iodide system towards PFC degradation. PFC photoreduction kinetics are observed to be dependent on PFC headgroup, perfluorocarbon chain length, initial PFC concentration, and iodide concentration. From 2 to 12, pH had no observable effect on PFC photoreduction kinetics, suggesting that the aquated electron was the predominant reductant with negligible contribution from the H-atom. A large number of gaseous fluorocarbon intermediates were semi-quantitatively identified and determined to account for ?25% of the initial PFOS carbon and fluorine. Reaction mechanisms that are consistent with kinetic observations are discussed. PMID:22025132

Park, Hyunwoong; Vecitis, Chad D; Cheng, Jie; Dalleska, Nathan F; Mader, Brian T; Hoffmann, Michael R

2011-12-01

414

Cold-development tool and technique for the ultimate resolution of ZEP520A to fabricate an EB master mold for nano-imprint lithography for 1Tbit/inch2 BPM development  

NASA Astrophysics Data System (ADS)

Cold-development is well-known for resolution enhancement on ZEP520A. Dipping a wafer in a developer solvent chilled by a freezer, such a typical method had been employed. But, it is obvious that the dip-development method has several inferiorities such as developer temperature instability, temperature inconsistency between developer and a wafer, water-condensation on drying. We then built a single wafer spin-develop tool, and established a process sequence, to solve those difficulties. And, we tried to see their effect down to -10degC over various developers. In specific, we tried to make hole patterns in hexagonal closest packing in 40nm, 35nm, 30nm, 25nm pitch, and examined holes pattern quality and resolution limit by varying setting temperature from room temperature to -10degC in the cold-development, as well as varying developer chemistry from the standard developer ZED N-50 (n-amyl acetate, 100%) to MiBK and IPA mixture which was a rinsing solvent mixture originally. We also examined the other developer (poor solvent mixture) we designed, N-50 and fluorocarbon (FC) mixture, MiBK and FC mixture, and IPA+FC mixture. This paper describes cold-development tool and technique, and its results down to minus (-) 10degC, for ZEP520A resolution enhancement to obtain 1Xnm bits (holes) in 25nm pitch to fabricate an EB master mold for Nano-Imprinting Lithography for 1Tbit/in2 bit patterned media (BPM) in HDD development and production.

Kobayashi, Hideo; Iyama, Hiromasa; Kagatsume, Takeshi; Watanabe, Tsuyoshi

2012-11-01

415

Krypton-85 health risk assessment for a nuclear fuel reprocessing plant  

SciTech Connect

The risks involved in the routine release of /sup 85/Kr from nuclear fuel reprocessing operations to the environment were compared to those resulting from the capture and storage of /sup 85/Kr. Instead of releasing the /sup 85/Kr to the environment when fuel is reprocessed, it can be captured, immobilized and stored. Two alternative methods of capturing /sup 85/Kr (cryogenic distillation and fluorocarbon absorption) and one method of immobilizing the captured gas (ion implantation/sputtering) were theoretically incorporated into a representative fuel reprocessing plant, the Barnwell Nuclear Fuel Plant, even though there are no known plans to start up this facility. Given the uncertainties in the models used to generate lifetime risk numbers (0.02 to 0.027 radiation induced fatal cancers expected in the occupational workforce and 0.017 fatal cancers in the general population), the differences in total risks for the three situations, (i.e., no-capture and two-capture alternatives) cannot be considered meaningful. It is possible that no risks would occur from any of the three situations. There is certainly no reason to conclude that risks from /sup 85/Kr routinely released to the environment are greater than those that would result from the other two situations considered. Present regulations mandate recovery and disposal of /sup 85/Kr from the off gases of a facility reprocessing spent fuel from commercial sources. Because of the lack of a clear-cut indication that recovery woud be beneficial, it does not seem prudent to burden the facilities with a requirement for /sup 85/Kr recovery, at least until operating experience demonstrates the incentive. The probable high aging of the early fuel to be processed and the higher dose resulting from the release of the unregulated /sup 3/H and /sup 14/C also encourage delaying implementation of the /sup 85/Kr recovery in the early plants.

Mellinger, P.J.; Brackenbush, L.W.; Tanner, J.E.; Gilbert, E.S.

1984-08-01

416

Effect of carbon enrichment induced by photoresist on highly selective SiO2 etching  

NASA Astrophysics Data System (ADS)

We propose two models to discuss the behavior of the selective etching of SiO2 to the underlying Si3N4 with changing wafer surface temperatures. For this investigation, three specimens, SiO2, Si3N4, and poly-Si, which are nonpatterned, photoresist-patterned, and poly-silicon-patterned, respectively, have been etched in a surface wave plasma system equipped with an electrostatic chuck for wafer temperature control. The coolant temperature, which controls the wafer temperature, has been changed from -20 to 50 °C. For the nonpatterned wafer, the etch rates of SiO2, Si3N4, and poly-Si increase and the selectivities decreases with wafer temperature. However, for the samples patterned with either photoresist or poly-Si, the etch rates of SiO2 decrease with wafer temperature. The temperature rise also leads to an enhancement of selectivity of SiO2/Si3N4, and the steeper profile angles. The presence of a masking layer, even for the poly-Si-patterned samples, results in a different etching behavior. This is because the sticking probability of the polymer precursor becomes smaller on the sidewall of the profile with the temperature increase. Therefore the thickness of polymer on the sidewall of the contact hole decreases, and the thickness of polymer on the bottom increases as the wafer temperature goes up. Comparing photoresist-patterned samples with poly-Si-patterned ones, we can corroborate the role of the photoresist mask layer, which provides a higher carbon-to-fluorine ratio at the near surface. The carbon enrichment accelerates more steeply the etch rate decrement of the substrate layer. In summary, there are two main contributions attributed by the substrate temperature: changing the sticking coefficient of the fluorocarbon precursor and enhancing the photoresist erosion.

Chu, Changwoong; Chi, Kyeong-Koo; Moon, Joo-Tae

2002-11-01

417

Two episodes of acute illness in a machine shop.  

PubMed Central

Following an explosion in a machine shop and temporary plant closure, on the day the plant returned to full operations a degreaser malfunctioned. Workers in the assembly room were exposed to trichloroethylene levels later estimated to have exceeded 220 ppm (OSHA PEL 100 ppm). The plant was evacuated and the degreaser taken out of operation. Blood testing for carbon monoxide (CO) on five employees found carboxyhemoglobin levels in excess of normal. The plant reopened the following morning. Over the next two weeks, 15 employees were seen by the plant nurses for similar complaints; although all returned to work, their carboxyhemoglobin levels, later found to be inaccurate, were reported by a local medical clinic to range from 13.7 to 20.0 percent. At the end of the second week, another outbreak of illness occurred, but carboxyhemoglobin, trichloroethylene, fluorocarbons, and methylene chloride were not elevated in all 17 persons tested; plant-wide monitoring for CO found no elevated levels. During the first outbreak of illness, cases were 2.26 times as likely to have entered the assembly room as noncases. During the second outbreak, cases were no more likely than noncases to have entered the assembly room. We believe the explosion, earlier toxic exposures and illness, and the misleading blood test results led to plant-wide anxiety which culminated in a collective stress reaction and the second outbreak. An open meeting with all employees, informing them of our findings, provided reassurance and no further episodes of illness occurred in this workforce. PMID:2751018

Sinks, T; Kerndt, P R; Wallingford, K M

1989-01-01

418

Phase segregation of sulfonate groups in Nafion interface lamellae, quantified via neutron reflectometry fitting techniques for multi-layered structures.  

PubMed

Neutron reflectometry analysis methods for under-determined, multi-layered structures are developed and used to determine the composition depth profile in cases where the structure is not known a priori. These methods, including statistical methods, sophisticated fitting routines, and coupling multiple data sets, are applied to hydrated and dehydrated Nafion nano-scaled films with thicknesses comparable to those found coating electrode particles in fuel cell catalyst layers. These results confirm the lamellar structure previously observed on hydrophilic substrates, and demonstrate that for hydrated films they can accurately be described as layers rich in both water and sulfonate groups alternating with water-poor layers containing an excess of fluorocarbon groups. The thickness of these layers increases slightly and the amplitude of the water volume fraction oscillation exponentially decreases away from the hydrophilic interface. For dehydrated films, the composition oscillations die out more rapidly. The Nafion-SiO2 substrate interface contains a partial monolayer of sulfonate groups bonded to the substrate and a large excess of water compared to that expected by the water-to-sulfonate ratio, ?, observed throughout the rest of the film. Films that were made thin enough to truncate this lamellar region showed a depth profile nearly identical to thicker films, indicating that there are no confinement or surface effects altering the structure. Comparing the SLD profile measured for films dried at 60 °C to modeled composition profiles derived by removing water from the hydrated lamellae suggests incomplete re-mixing of the polymer groups upon dehydration, indicated limited polymer mobility in these Nafion thin films. PMID:24981163

DeCaluwe, Steven C; Kienzle, Paul A; Bhargava, Pavan; Baker, Andrew M; Dura, Joseph A

2014-08-21

419

Sorption of Perfluorochemicals to Matrices Relevant to Sites Impacted by Aqueous Film-Forming Foam  

NASA Astrophysics Data System (ADS)

Perfluorochemicals are a class of emerging contaminants consisting of fluorinated surfactants that are chemically and thermally stable and which contain a fluorocarbon tail that is both hydro- and oleophobic. Because of these unique properties, PFCs have a wide variety of uses including food paper packaging products, stain repellants, nonstick coatings, and aqueous film-forming foams (AFFF). At fire-training facilities, repeated application of AFFF is used to extinguish hydrocarbon fuel fires ignited for training purposes. The presence of perfluochemicals (PFCs) in groundwater as a result of repeated AFFF application at these facilities has been documented. Due to factors such as the recent push towards regulation of PFCs in drinking water, concerns have arisen about the fate of these compounds in the subsurface. Groundwater plumes containing PFC subclasses such as perfluorocarboxylic acids (PFCAs), perfluoroalkylsulfonates (PFAS), and fluorotelomer sulfonates (FtSs) in the ?g/L to mg/L range have been detected. These plumes also may contain co-contaminants such as hydrocarbon fuel components and chlorinated solvents, some of which may exist as nonaqueous phase liquids (NAPL). This study examined the sorption of PFCs to soil and aquifer material across the concentration range applicable to AFFF-impacted sites (?g/L - mg/L) and looked at the impact of co-contaminants, including NAPL, on PFC sorption. PFC sorption was variable and indicated that similar to previous work on PFC sorption to sediment, subsurface PFC transport will depend on factors such as the sorbent organic carbon content, PFC subclass, solution chemistry, and PFC chain length.

Sepulvado, J.; Higgins, C.

2011-12-01

420

Bubble departure in the direct-contact boiling field with a continuous liquid-liquid interface  

SciTech Connect

Behavior of vapor bubbles was experimentally investigated in the boiling field where a volatile liquid layer of per-fluorocarbon PF5050 (boiling point 306K) was directly in contact with an immiscible hot liquid layer of water above it. Heat was supplied to the continuous liquid-liquid interface by the impingement of the downward hot water jet. Vapor bubbles were generated not only from this continuous interface but from a large number of PF5050 droplets floating on it. According to precise observation, incipience of boiling did not occur at the liquid-liquid interface but in the PF5050 liquid close to the interface in both cases of continuous and dispersed interfaces. As a result, the bubbles broke up the thin PF5050 liquid film above them and rose up into the water layer. This bubble departure phenomenon, which does not occur in the ordinary pool boiling field on the solid heating wall, is very important to evaluate the heat transfer performance in the present direct-contact boiling system. For modeling this behavior, sizes of the bubbles were measured at the moment just after they were released into the water pool. Volumes of the bubbles were larger in the case of departing from the continuous liquid-liquid interface than from the droplets. This tendency could be explained by taking into account the buoyancy force acting on unit area of the thin PF5050 liquid film above the bubble before departure, which was one of the most important parameters for the liquid film breakdown. (author)

Kadoguchi, Katsuhiko [Energy Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569 (Japan)

2007-01-15

421

Polymer Composites for High-Temperature Proton-Exchange Membrane Fuel Cells  

NASA Astrophysics Data System (ADS)

Recent advances in composite proton-exchange membranes for fuel cell applications at elevated temperature and low relative humidity are briefly reviewed in this chapter. Although a majority of research has focused on new sulfonated hydrocarbon and fluorocarbon polymers and their blends to directly enhance high temperature performance, we emphasize on polymer/inorganic composite membranes with the aim of improving the mechanical strength, thermal stability, and proton conductivity, which depend on water retention at elevated temperature and low relative humidity conditions. The polymer systems include perfluoronated polymers such as Nafion, sulfonated poly(arylene ether)s, polybenzimidazoles (PBI)s, and many others. The inorganic proton conductors are silica, heteropolyacids (HPA)s, layered zirconium phosphates, and liquid phosphoric acid. Direct use of sol-gel silica requires pressurization of fuel cells to maintain 100% relative humidity for high proton conductivity above 100°C. Direct incorporation of HPAs such as phosphotungstic acid (PTA) into polyelectrolyte membranes is capable of improving both proton conductivity and fuel cell performance above 100°C; however, they tend to leach out of the membrane whenever fuel cell flooding happens. To prevent HPA leaching, amine-functionalized mesoporous silica is used to immobilize PTA in Nafion membranes, whose proton conductivity and fuel cell performance are discussed. Compared with Nafion, sulfonated poly(arylene ether)s such as sulfonated poly(arylene ether sulfone)s are cost-effective materials with excellent thermal and electrochemical stability. Their composites with HPAs show increased proton conductivity at elevated temperatures when fully hydrated. Organic/inorganic hybrid membranes from acid-doped PBIs and other polymers are also discussed.

Zhu, Xiuling; Liu, Yuxiu; Zhu, Lei

422

Novel low-permittivity dielectrics for Si-based microelectronics  

SciTech Connect

The purpose of this laboratory-directed research and development (LDRD) project was to develop and assess novel low-permittivity dielectric materials for applications as interlevel dielectrics (ILDs) in Si-based microelectronics. There were three classes of materials investigated: (1) novel covalently-bonded ceramics containing carbon, boron, and/or nitrogen, (2) fluorinated SiO{sub 2} (SiOF), and (3) plasma polymerized fluorocarbon (PPFC). The specific advantages and disadvantages for each potential low k ILD material were evaluated. It was discovered that highly energetic deposition processes are required for the formation of thermally and environmentally stable carbon or boron nitride ceramics, and the resulting films may have many potentially valuable applications, such as diffusion barriers, tribological coatings, micro-sensor materials, etc. The films are not suitable as low k ILDs, however, because the highly energetic deposition process leads to films with high atomic density, and this leads to high dielectric constants. SiOF shows a promise as low k ILD material for near-term applications, but special passivation or encapsulation strategies may be required in order to reduce two instability problems that the authors have discovered: moisture absorption and thermal instability of the SiOF/Al interface. PPFC films offer promise for even lower dielectric constant ILDs than SiOF, but it will be necessary to develop new strategies to passivate the free radicals in the films generated during deposition. These free radicals lead to increase in dielectric loss over time when the films are exposed to room ambient conditions.

Sullivan, J.P.

1997-09-01

423

Surface Modification of Droplet Polymeric Microfluidic Devices for the Stable and Continuous Generation of Aqueous Droplets  

PubMed Central

Droplet microfluidics performed in poly(methylmethacrylate), PMMA, microfluidic devices resu