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1

water-soluble fluorocarbon coating  

NASA Technical Reports Server (NTRS)

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

Nanelli, P.

1979-01-01

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

Industrial research on alternative fluorocarbons.  

PubMed

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

Trochimowicz, H J

1993-05-01

4

Functionally terminated liquid nitroso fluorocarbon terpolymers  

NASA Technical Reports Server (NTRS)

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

Mayes, N.; Marcellis, A.

1972-01-01

5

Blood Levels of Fluorocarbon Related to Cardiac Sensitization  

Microsoft Academic Search

Unanesthetized beagle dogs were exposed to concentrations of fluorocarbon-11 and fluorocarbon-12 which had been reported to produce cardiac sensitization. During and after the exposure, arterial and venous blood samples were obtained for fluorocarbon analysis. The blood concentration rose rapidly during the first few minutes of the 10-minute exposure and more slowly thereafter. When the exposure was terminated, there was a

A. AZAR; H. J. TROCHIMOWICZ; J. B. TERRILL; L. S. MULLIN

1973-01-01

6

Fluorocarbon Adsorption in Hierarchical Porous Frameworks  

SciTech Connect

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

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

2014-07-09

7

Fluorocarbons and fluorinated amphiphiles in drug delivery and biomedical research  

Microsoft Academic Search

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

Marie Pierre Krafft

2001-01-01

8

Fluorocarbon adsorption in hierarchical porous frameworks.  

PubMed

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. PMID:25006832

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

2014-01-01

9

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

10

Materials analysis of fluorocarbon films for MEMS applications  

Microsoft Academic Search

In this paper the results of the materials analysis of fluorocarbon (FC) films are presented. The properties of the fluorocarbon films are comparable to those of polytetrafluoroethylene (PTFE), better known under the trademarks such as teflon and fluon. The properties of PTFE are desirable for MEMS applications and enable new designs, new applications and new technological processing routes for microsystems.

J. Elders; H. V. Jansert; M. Elwenspoek

1994-01-01

11

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

12

Surface kinetics modeling of silicon oxide etching in fluorocarbon plasmas  

E-print Network

Fluorocarbon plasma for silicon oxide etching is a complicated system involving many ion and neutral species. Depending on the plasma condition, many difficulties arise such as RIE lag, etch stop, and low selectivity to ...

Kwon, Ohseung, 1969-

2004-01-01

13

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

NASA Technical Reports Server (NTRS)

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

Talcott, N. A., Jr.

1977-01-01

14

Fluorocarbon seal replaces metal piston ring in low density gas environment  

NASA Technical Reports Server (NTRS)

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

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

1967-01-01

15

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

16

EPR studies on fluorocarbon microspheres. Dynamic polarization of fluorine nuclei and adsorbed He3  

E-print Network

1033 EPR studies on fluorocarbon microspheres. Dynamic polarization of fluorine nuclei and adsorbed.8 1018/cc) of electronic paramagnetic centres in microspheres of fluorocarbon. These centres are peroxy]. Studies of TB of He3 adsorbed on a supposedly clean wall, namely microspheres of fluorocarbon (1), were

Paris-Sud XI, Université de

17

Effect of fluorocarbons on acetylcholinesterase activity and some counter measures  

NASA Technical Reports Server (NTRS)

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

Young, W.; Parker, J. A.

1975-01-01

18

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

NASA Technical Reports Server (NTRS)

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

Predmore, Roamer E.; Canham, John S.

2002-01-01

19

Simultaneous, multilayer plasma etching and deposition of fluorocarbon layers on silicon  

NASA Astrophysics Data System (ADS)

The plasma etching and deposition of a fluorocarbon layer on a silicon substrate are modeled by the simultaneous etching and deposition of a stack of fluorocarbon monolayers. Langmuir kinetics apply in each of the monolayers to a depth where the energy of the bombarding ions exceeds or equals the threshold energy for breaking carbon fluorine bonds. The ion energy controls many of the terms in the etch rate and deposition rate expressions. The model is based on the diffusion of fluorine etchant through the fluorocarbon layer to the silicon substrate. The deposition and etching of the fluorocarbon layer are ion assisted; the etching of the silicon is thermal and is assumed self-similar based on experiments. The model covers three regimes: reactive sputtering, fluorocarbon suppression, and fluorocarbon deposition. Etch and deposition curves model CF+ ion beam deposition and etch on silicon and CHF3 and C2F6 etch and deposition on fluorocarbon covered silicon substrates.

Abraham-Shrauner, Barbara

2003-10-01

20

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

21

Effect of capacitive coupling on inductively coupled fluorocarbon plasma processing  

SciTech Connect

This article describes results obtained using various plasma and surface diagnostics in a study of inductively coupled fluorocarbon plasmas in which the amount of capacitive coupling was systematically varied. It is found that the plasma density decreases while the electron temperature increases as the amount of capacitive coupling is increased at a constant source power level. The rate at which the dielectric coupling window is eroded is found to scale with both the peak-to-peak rf voltage and the ion current density, and the dielectric window erosion is found to influence the resulting plasma gas-phase chemistry. The changes in plasma electrical and chemical characteristics have a large impact on the surface processes occurring in inductively coupled fluorocarbon plasmas such as fluorocarbon deposition, fluorocarbon etching, SiO{sub 2} etching and Si etching. Further, we show how the selective SiO{sub 2}-to-Si etch process changes with varying capacitive coupling. {copyright} {ital 1999 American Vacuum Society.}

Schaepkens, M.; Rueger, N.R.; Beulens, J.J.; Li, X.; Standaert, T.E.; Matsuo, P.J.; Oehrlein, G.S. [University at Albany, State University of New York, Albany, New York 12222 (United States)] [University at Albany, State University of New York, Albany, New York 12222 (United States)

1999-11-01

22

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

23

Plasma chemistry of fluorocarbon RF discharges used for dry etching  

Microsoft Academic Search

Investigations on capacitively coupled RF plasma in flurocarbon gases excited at 13.56 MHz are reported. These plasmas are commonly used for many applications where a substrate must be etched, for example in the manufacturing of integrated circuits. Diagnostics to measure the densities of both neutral and charged species in RF plasma of fluorocarbon gases that are widely used for etching

Marco Haverlag

1991-01-01

24

Reactive airways dysfunction syndrome following exposure to a fluorocarbon.  

PubMed

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

de la Hoz, R E

1999-05-01

25

Fluorocarbon 113 exposure and cardiac dysrhythmias among aerospace workers  

Microsoft Academic Search

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

Grace M. Egeland; Thomas F. Bloom; Teresa M. Schnorr; Richard W. Hornung; Anthony J. Suruda; Kathleen K. Wille

1992-01-01

26

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

27

Cardiac arrhythmia in refrigerator repairmen exposed to fluorocarbons.  

PubMed Central

A field study of 89 refrigerator repairmen was carried out to ascertain whether occupational exposure to fluorocarbons induces cardiac arrhythmia. The concentrations of fluorocarbons in the breathing zones and the heart activity were recorded simultaneously. Most cooling systems contained FC 12 or FC 22. The highest level recorded in one minute was 14,000 ppm and the highest time weighted level during eight hours was 280 ppm. Two types of arrhythmia were recorded, ectopic beats and sudden bradycardia. A within subject comparison design was applied and the main parameter was the difference in arrhythmia frequencies between exposed and unexposed periods. No appreciable differences between exposed and unexposed periods and no consistent dose effect relations were observed, although subjects in the medium exposure category showed a difference of borderline significance (Wilcoxon's test: p = 0.05, one tailed). The frequencies of arrhythmia when unexposed were somewhat higher than previously reported. Misclassification of the exposure and the possible confounding effect of physical workload and psychological strain may have obscured a causal relation and therefore a minor effect cannot be ruled out. The results do not support the notion that fluorocarbons induce cardiac arrhythmia in occupationally exposed refrigerator repairmen. PMID:2328227

Edling, C; Ohlson, C G; Ljungkvist, G; Oliv, A; Söderholm, B

1990-01-01

28

Effects of nano-fluorocarbon coating on icing  

NASA Astrophysics Data System (ADS)

Icing is a common phenomenon in many fields, from aeronautics to power lines. Recently, researchers have paid much attention on the superhydrophobic surface as one of the favorable anti-icing techniques. In the present study, we investigated the performance of water icing on a superhydrophobic surface with a nano-fluorocarbon film in the average thickness around 10 nm. The surface topographies and wettabilities were characterized by a scanning electron microscopy system and a video-based contact angle measurement system respectively. To investigate the effects of this nano-fluorocarbon coating on water icing, the water droplet shape, the starting icing time and the whole icing process were observed on both the coated and uncoated surface. It was found that the coated surface has a good ability to retard the starting time of icing while the whole icing time on the coated surface was longer compared the uncoated one under the experimental conditions. The test results showed that the nano-fluorocarbon coating expresses a good anti-icing performance and can be used as a coating material to avoid ice-blocking in the dynamic ice-making system.

Wang, Hong; He, Guogeng; Tian, Qiqi

2012-07-01

29

Robust Ultralow-k Dielectric (Fluorocarbon) Deposition by Microwave Plasma-Enhanced Chemical Vapor Deposition  

NASA Astrophysics Data System (ADS)

A robust fluorocarbon film was successfully deposited on a substrate at a temperature above 400 °C by the new microwave plasma-enhanced chemical vapor deposition (MWPE-CVD) method using the linear C5F8 precursor instead of a conventional cyclic C5F8 one. The fluorocarbon performed keeping the dielectric constant low as a value of 2.25 by controlling the molecular structure forming cross-linked poly(tetrafluoroethylene) (PTFE) chains with configurational carbon atoms. The novel fluorocarbon demonstrates less fluorine degassing at an elevated temperature, with high mechanical strength and without degradation of adhesion of the fluorocarbon film to SiCN and SiOx stacked films after thermal stress at 400 °C and 1 atm N2 for 1 h. Consequently, this robust fluorocarbon film is considered a promising candidate for general porous silicon materials with applications to practical integration processes as an interlayer dielectric.

Kikuchi, Yoshiyuki; Miyatani, Kotaro; Kobayashi, Yasuo; Kawamura, Kohei; Nemoto, Takenao; Nakamura, Masahiro; Matsumoto, Hirokazu; Ito, Azumi; Shirotori, Akihide; Nozawa, Toshihisa; Matsuoka, Takaaki

2012-05-01

30

Evidence of direct SiO2 etching by fluorocarbon molecules under ion bombardment  

NASA Astrophysics Data System (ADS)

In a beam apparatus, influence of fluorocarbon gas (C5F8, C4F8, and CF4 molecules) flux onto SiO2 etching reaction is investigated in comparison to a case of CF2 radical flux. Fluorocarbon molecules or CF2 radicals are incident onto SiO2 surface with Ar + beam of energy 100-900eV. Atomic composition of SiO2 surface under the ion and molecule incidence is measured by in situ x-ray photoelectron spectroscopy. Fluorocarbon/Ar + co-incidence enhances the SiO2 etching compared with pure Ar + incidence, suggesting the etching effect of fluorocarbon molecules under Ar+ bombardment. In the case of C5F8/Ar+ co-incidence, formation of fluorocarbon layer is observed as the case of CF2/Ar + co-incidence. Etching yields of SiO2 by C5F8/Ar + and CF2/Ar + co-incidences are measured for different Ar+ incident energies and fluorocarbon/Ar+ flux ratios. The etching yield increases monotonically with the Ar+ incident energy, and reaches the value of 2.4 at 900eV in case of C5F8, which is about 1.5 times as high as in the CF2 case. In the case of C5F8 and CF2, a phenomenon like etch stop, with formation of a thick fluorocarbon layer, is observed for larger fluorocarbon flux, with the threshold of the fluorocarbon/Ar+ flux, ratio between 2.5 and 25. These results suggest a significant contribution of direct SiO2 etching by fluorocarbon molecules in practical etching reactors, especially in case of the C5F8 molecule.

Takada, N.; Toyoda, H.; Murakami, I.; Sugai, H.

2005-01-01

31

Discovery during Hydrogen Annealing: Formation of Nanoscale Fluorocarbon Tubular Structures  

NASA Astrophysics Data System (ADS)

A novel fabrication method for nanoscale tubular structures is presented in this paper. The tubular structures can be obtained by heating single-crystal silicon trenches or pillars formed by the inductively coupled plasma reactive-ion etching (ICP-RIE) Bosch process in hydrogen ambient. The importance of initial vacuum in the reaction chamber for tube formation and the tube formation mechanism were discussed. The components and sidewall size of the tubular structure were also studied to verify that the tube is made of the fluorocarbon (CF) passivation layer deposited by the Bosch process. The CF tubular structure would be a promising structure for BioMEMS.

Hao, Xiuchun; Tanaka, Sinya; Masuda, Atsuhiko; Maenaka, Kazusuke; Higuchi, Kohei

2013-09-01

32

Spraylon fluorocarbon encapsulation for silicon solar cell arrays, phase 3  

NASA Technical Reports Server (NTRS)

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

Naes, L. G.

1978-01-01

33

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

34

Gas embolism due to intravenous FC 80 liquid fluorocarbon.  

PubMed

Lethal gas embolism always occurs after FC 80 liquid fluorocarbon is injected intravenously (0.1 ml/kg body mass) in dogs breathing room air but not in dogs breathing oxygenated FC 80 liquid fluorocarbon. Gas embolism is not prevented in dogs that have been injected intravenously with FC 80 when they are exposed to 2 ATA (atmospheres absolute) 20% 02-80% N2, 9 ATA 5% O2-95% He, or 1 ATA 100%, O2. In dogs that die of FC 80-induced gas embolism, free gas in the right atrium contains approximately 0.5 g FC 80/liter, and Po2 and Pco2 in the gas are in equilibrium with their corresponding tensions in right atrial blood. These observations are consistent with the hypothesis that PFC 80 in alveolar gas does not equilibrate with PFC 80 (55 mmHg) in blood. The total gas tension in pulmonary capillary blood containing FC 80 and its vapor thus exceeds the total tension of alveolar gases (atmospheric pressure). Bubbles of O2, CO2, N2, FC 80, and water vapor form in the regions of the pulmonary capillary bed where the total tension of gases dissolved in blood exceeds the absolute blood pressure. PMID:931904

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

1976-05-01

35

Enhanced removal of radioactive particles by fluorocarbon surfactant solutions  

SciTech Connect

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

Kaiser, R.; Harling, O.K. [Entropic Systems, Inc., Winchester, MA (United States)

1993-08-01

36

Selective Plasma Deposition of Fluorocarbon Films on SAMs  

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

37

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

PubMed

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

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

2012-10-01

38

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

PubMed

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

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

2014-06-11

39

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

40

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

41

Detection of common alternative fluorocarbons using fluorine-specific atomic emission detector  

NASA Astrophysics Data System (ADS)

It is now certain that chlorine- and bromine-containing species are at least partially responsible for declining stratospheric ozone levels and the Antarctic ozone hole. The alternative fluorocarbons (AFCs), which are environmentally superior to the chlorofluorocarbons (CFCs), were developed as a replacement. The AFCs consist of both the hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs). This dissertation describes the development of a fluorine-specific atomic emission detector for monitoring alternative fluorocarbons (AFCs) compounds and their degradation products. This detector uses alternating current discharge plasma as the ionization and excitation source, and helium is used as the plasma gas. A monochromator with a PMT is used for detection. The detection limit obtained with the fluorine-specific atomic emission detector apparently allows this detector to be used in monitoring the alternative fluorocarbons in the lower atmosphere at current concentration levels.

Sousa, Sonia Regina

42

Response of the rabbit lung as a criterion of safety for fluorocarbon breathing and blood substitutes.  

PubMed

From the first liquid breathing experiments until now, the lung, not surprisingly, has played a central role in the evolution of fluorocarbon blood substitutes. The first breathable fluorocarbon, a mixture of F-alkylfurans(FC75), bp 102 degrees C, while a poor solvent for the lung's lining and a good solvent for oxygen and carbon dioxide, proved to cause a characteristic gas/vapor microbubble embolism following intravenous administration as an emulsion. Higher boiling fluorocarbons, e.g. F-tributylamine (FC47), bp 174 degrees C, do not produce such gas-vapor emboli. However, intermediate boiling compounds such as F-decalin (PP5), bp 141 degrees C, produce lungs which, although they certainly appear not to contain microbubble emboli, do not collapse when the thorax is opened. Such hyperinflated non-collapsible lungs (HNCL) occur in the rabbit after the intravenous infusion of F-decalin emulsions as well as after the intratracheal infusion of F-decalin neat liquid. F-decalin induced HNCL retain their appearance and low specific gravity for many weeks, gradually returning toward normal after many months. F-methyl decalin, bp 165 degrees C, does not cause HNCL after intravascular or intratracheal administration. Fluorocarbons having boiling points between 140 degrees C and 165 degrees C are being tested in order to find a perfluorinate with the highest transpiration rate, and hence vapor pressure, compatible with an acceptable body dwell time. We have given fluorocarbons intratracheally to 75, intravenously to 221 and both intratracheally and intravenously to 8 rabbits. Free radical trapping agents, antineutrophil, antiinflammatory and other drugs have been administered without appreciable decrease of HNCL. Fluorocarbon critical solution temperature, lipid solubility, emulsifiability, and other physicochemical properties may mediate the pulmonary effect. One method of preventing and treating low dose F-decalin-induced HNCL in rabbits is described. PMID:1391430

Clark, L C; Hoffmann, R E; Davis, S L

1992-01-01

43

Negative Ions in Dual-Frequency Capacitively Coupled Fluorocarbon Plasmas  

NASA Astrophysics Data System (ADS)

Dual-frequency capacitively coupled plasmas in fluorocarbon-based gases are widely used for etching SiO2-based dielectric films in integrated circuit manufacture. We have studied a customized 2 + 27 MHz industrial etch reactor, running in Ar/O2 with c-C4F8 or CF4 gas mixtures at pressures in the region of 50 mTorr (6.6 Pa). Negative ions could play an important role in this type of plasma. The presence of negative ions will modify the positive ion flux arriving at a surface, and may even reach the surface and participate in etching. We have measured the electron density using a microwave hairpin resonator [1] and the positive ion flux with an ion flux probe [2]: the ratio of these two quantities varies strongly with gas chemistry and gives evidence for the presence of negative ions [3]. For example, by varying the flow of c-C4F8 in an Ar/O2 mixture this ratio shows evidence of high electronegativity for high c-C4F8 flowrates. We have also measured the negative fluorine ion, F^-, density directly by high-sensitivity cavity ring-down absorption spectroscopy [4] in the wavelength range 340 to 360 nm to determine the density of absorbing F^- ions from the known photo-detachment cross-section. The F^- densities were seen to reach values in the 10^11cm-3 range, giving electronegative fractions, ? = n-/ne, of up to 15 when used in conjunction with the hairpin probe measurements. We acknowledge financial assistance from Lam Research Corporation. [1] Piejak et al, J. Appl. Phys. 95 (2004), 3785-3791 [2] Braithwaite et al, Plasma Sources Sci. Technol., 5 (1996), 677-684 [3] Chabert et al, Plasma Sources Sci. Technol., 8 (1999), 561-566 [4] Booth et al, Appl. Phys. Lett., 88 (2006), 151502

Booth, Jean-Paul

2006-10-01

44

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

45

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

Microsoft Academic Search

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 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 0.4MPa, and at temperatures between 253 and 303K. The purity of the C3F8 and

V Vacek; G Hallewell; S Lindsay

2001-01-01

46

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

E-print Network

with the goal of combining plasma chemistry and surface chemistry in a self-consistent fashion. The SKM obtains during Si etching using fluorocarbon gases in an induc- tively coupled plasma ICP reactor.4 They observed equipment, surface chemistry, and molecular dynamics mod- els have been successful in separately addressing

Kushner, Mark

47

Fluorocarbon and PTFE thermodegradation and contamination modeling in a space habitat  

Microsoft Academic Search

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

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

1993-01-01

48

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

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

49

Plasma-deposited fluorocarbon coatings for passive and active integrated optical devices  

Microsoft Academic Search

Amorphous fluorocarbon polymers are attractive materials for optical applications because of their high transparency at wavelengths up to 3 micrometers because of the absence of C-H bonds. since 1989 DuPont's amorphous fluoropolymer Teflon AF is available, films of which can be fabricated by means of spin, spray, or dip coating from solution or by use of compression or injection molding

W. Wirges; S. Bauer-Gogonea; S. Bauer; Reimund Gerhard-Multhaupt; Ludvik Martinu; J. E. Klemberg-Sapieha; M. R. Wertheimer

1994-01-01

50

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

51

Space and Time Resolved Measurements of F^- Density in High-Density Fluorocarbon Plasmas by Laser Photodetachment  

Microsoft Academic Search

The importance of F^- has been pointed out in ion-enhanced plasma etching of SiO_2\\/Si with fluorocarbon plasmas. However, the difficulty in negative ion diagnostics in the fluorocarbon plasmas has led us to the paucity of the knowledge of the production and loss mechanisms of F^-. This is partly because that conventional Langmuir probes do not work in the flurocarbon plasmas

D. Hayashi; N. Takada; K. Sasaki; K. Kadota

1997-01-01

52

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

53

Improving adhesion between a segmented poly(ether-urethane) and a fluorocarbon copolymer coating  

SciTech Connect

A moisture barrier coating of Kel-F 800, developed at LLNL to reduce uranium corrosion, had to be bonded to a porous ceramic. The adhesive could not bond too strongly or react with the coating and jeopardize its barrier properties. Methods of improving adhesion to the Kel-F coating were studied. Silane and titanate coupling agents and a fluorocarbon surfactant were somewhat effective at increasing adhesion depending on the application procedure. X-ray photoelectron spectroscopy (XPS) was used to demonstrate the presence of fluorosurfactant at the fracture interface. Postcuring at elevated temperatures (85/sup 0/C) also significantly improved adhesive strength to the fluorocarbon coating. This was attributed to thermal acceleration to interfacial diffusion of the urethane adhesive into the fluoropolymer surface.

Hoffman, D.M.; Walkup, C.M.; Chiu, I.L.

1984-01-01

54

A study of the deposition of polymeric material onto surfaces from fluorocarbon RF plasmas  

Microsoft Academic Search

A series of fluorocarbon gases, viz., CF4, C2F6, C3F8, and CHF3, have been compared for their relative tendencies to deposit polymeric material onto various surfaces, including Si and SiO2, under RF plasma conditions. The plasmas were examined by optical emission spectroscopy. C3F8 and CHF3 were found to produce the highest yields of polymers, although these exhibited significant differences in structure

P. J. Astell-Burt; J. A. Cairns; A. K. Cheetham; R. M. Hazel

1986-01-01

55

Moisture absorption studies of fluorocarbon films deposited from pentafluoroethane and octafluorocyclobutane plasmas  

Microsoft Academic Search

The moisture absorption and diffusion characteristics of fluorocarbon films deposited from pentafluoroethane (PFE) and octafluorocyclobutane\\u000a C4F8 plasmas are presented. The moisture absorption studies were carried out using a quartz crystal microbalance in a controlled\\u000a environment. X-ray photoelectron spectroscopy and Fourier transform infrared (IR) spectroscopy were used to monitor the changes\\u000a in bulk and surface chemical structure and composition of the

Ravindra V. Tanikella; Sairam Agraharam; Sue A. Bidstrup Allen; Dennis W. Hess; Paul A. Kohl

2002-01-01

56

The Effect of Electrode Gap on CF2 Distribution in Fluorocarbon Plasmas  

Microsoft Academic Search

Previous studies on fluorocarbon plasmas in parallel-plate reactors have shown that reactive species density distributions, cleaning rates, and other plasma properties are correlated to the rf current measured at the grounded electrode, I_ge. I_ge changes with electrode gap, which can be varied to optimize plasma performance. Here, we investigated correlations between electrode gap, electrical parameters, and the spatial distribution of

Kristen L. Steffens; Mark Sobolewski

1999-01-01

57

Heavy fluorocarbon liquids for a phase-conjugated stimulated Brillouin scattering mirror.  

PubMed

Heavy fluorocarbon liquids were found to be an ideal medium for high-power stimulated Brillouin scattering experiments. Fluorinert FC-75 gives high reflectivity, near 98%, and excellent fidelity in phase conjugation of 14-J, 18-ns optical pulses. The complete removal of microparticle impurities was found to be essential for avoiding laser damage in a high-energy operation. A method of purification based on ultrafiltration has been developed. PMID:18253400

Yoshida, H; Kmetik, V; Fujita, H; Nakatsuka, M; Yamanaka, T; Yoshida, K

1997-06-01

58

Wettability of polymeric solids by ternary mixtures composed of hydrocarbon and fluorocarbon nonionic surfactants.  

PubMed

Contact angle (?) measurements on poly(tetrafluoroethylene) (PTFE) and polymethyl methacrylate (PMMA) surface were carried out for the systems containing ternary mixtures of surfactants composed of: p-(1,1,3,3-tetramethylbutyl)phenoxypoly(ethylene glycols), Triton X-100 (TX100), Triton X-165 (TX165) and Triton X-114 (TX114), and fluorocarbon surfactants, Zonyl FSN100 (FSN100) and Zonyl FSO100 (FSO100). The aqueous solutions of ternary surfactant mixtures were prepared by adding TX114, FSN100 or FSO100 to binary mixtures of TX100+TX165, where the synergistic effect in the reduction of the surface tension of water (?(LV)) was determined. From the obtained contact angle values, the relationships between cos?, the adhesion tension and surface tension of solutions, cos? and the reciprocal of the surface tension were determined. On the basis of these relationships, the correlation between the critical surface tension of PTFE and PMMA wetting and the surface tension of these polymers as well as the work of adhesion of aqueous solutions of ternary surfactant mixtures to PTFE and PMMA surface were discussed. The critical surface tension of PTFE and PMMA wetting, ?(C), determined from the contact angle measurements of aqueous solutions of surfactants including FSN100 or FSO100 was also discussed in the light of the surface tension changes of PTFE and PMMA under the influence of film formation by fluorocarbon surfactants on the surface of these polymers. The ?(C) values of the studied polymeric solids were found to be different for the mixtures composed of hydrocarbon surfactants in comparison with those of hydrocarbon and fluorocarbon surfactants. In the solutions containing fluorocarbon surfactants, the ?(C) values were different taking into account the contact angle in the range of FSN100 and FSO100 concentration corresponding to their unsaturated monolayer at water-air interface or to that saturated. PMID:21821260

Szymczyk, Katarzyna

2011-11-01

59

Wettability of polymeric solids by ternary mixtures composed of hydrocarbon and fluorocarbon nonionic surfactants  

Microsoft Academic Search

Contact angle (?) measurements on poly(tetrafluoroethylene) (PTFE) and polymethyl methacrylate (PMMA) surface were carried out for the systems containing ternary mixtures of surfactants composed of: p-(1,1,3,3-tetramethylbutyl)phenoxypoly(ethylene glycols), Triton X-100 (TX100), Triton X-165 (TX165) and Triton X-114 (TX114), and fluorocarbon surfactants, Zonyl FSN100 (FSN100) and Zonyl FSO100 (FSO100).The aqueous solutions of ternary surfactant mixtures were prepared by adding TX114, FSN100 or

Katarzyna Szymczyk

2011-01-01

60

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

61

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

62

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

63

Effects of radio frequency bias frequency and radio frequency bias pulsing on SiO{sub 2} feature etching in inductively coupled fluorocarbon plasmas  

SciTech Connect

The effect of radio frequency (rf) bias frequency on SiO{sub 2} feature etching using inductively coupled fluorocarbon plasmas is investigated. It is found that the rf bias frequency can have an important effect on SiO{sub 2} feature etch rate, microtrenching phenomena, and SiO{sub 2}-to-photoresist etch selectivity. In addition, the effect of rf bias pulsing on inductively coupled fluorocarbon plasma SiO{sub 2} etching has been studied and a model that describes the data well is presented. The model assumes that fluorocarbon deposition occurs while the rf bias is off, fluorocarbon etching occurs during the first part of time that the bias is on, and substrate etching occurs once the fluorocarbon material has been removed from the substrate. (c) 2000 American Vacuum Society.

Schaepkens, M. [Physics Department, University at Albany, Albany, New York 12222 (United States)] [Physics Department, University at Albany, Albany, New York 12222 (United States); Oehrlein, G. S. [Physics Department, University at Albany, Albany, New York 12222 (United States)] [Physics Department, University at Albany, Albany, New York 12222 (United States); Cook, J. M. [Lam Research Corporation, Fremont, California 94538-6470 (United States)] [Lam Research Corporation, Fremont, California 94538-6470 (United States)

2000-03-01

64

In situ analysis of aqueous structure and adsorption at fluorocarbon, hydrocarbon and mineral surfaces  

NASA Astrophysics Data System (ADS)

Altering and controlling the properties of solid surfaces in aqueous or other liquid phase environments has been a sought after objective for decades. With the discovery of chemisorbed self-assembled monolayers, this dream has become a reality. Oxide and metal surfaces can now be readily coated with an array of commercially available products to produce a desired fnctionality. The presence of these coatings on solid surfaces affects properties of the interfacial region by altering interfacial electrostatic fields, changing the structure of interfacial water molecules and altering the interactions of adsorbed species. This dissertation reports on in situ studies of adsorption at several solid/aqueous interfaces using vibrational sum-frequency spectroscopy, a surface specific technique. These studies are augmented by the use of atomic force microscopy and contact angle goniometry to characterize the prepared surfaces and their interactions with adsorbates. The studies investigate how changes in the surface structure and chemistry, as well as the bulk aqueous phase, affect interfacial structure. The studies within are primarily focused on the interactions of water with bare and functionalized fused silica and the relationship between the aqueous phase composition and the structure of fluorocarbon and hydrocarbon self-assembled monolayers. The variations in aqueous structure are then examined in detail using ionic strength controlled experiments to understand the direct interactions of water hydrophobically coated silica. This analysis is followed by an investigation of the competitive adsorption of methanol and water at fluorocarbon and hydrocarbon monolayers which show spectroscopic signatures of the interaction strength between fluorocarbons and hydrocarbons. Further studies are performed using butylammonium chloride to verify these spectroscopic signatures and reveal different molecular structures of adsorbed species at chemically different hydrophobic surfaces. Lastly, specific ion effects on the CaF2/water interface are shown using equilibrium and time-resolved sum-frequency spectroscopy. The results of all these studies have implications for an array of surface chemical applications from mineral flotation to biocompatibility. This dissertation includes previously published co-authored material.

Hopkins, Adam Justin

65

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

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

2015-02-01

67

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

68

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

SciTech Connect

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

Hogen-Esch, T.E.

1996-11-01

69

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

NASA Technical Reports Server (NTRS)

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

Alston, W. B.

1973-01-01

70

Phase behavior and microstructures of nonionic fluorocarbon surfactant in aqueous systems.  

PubMed

The phase behavior and self-assembled structures of perfluoroalkyl sulfonamide ethoxylate, C8F17SO2N(C3H7)(CH2CH2O)20H (abbreviated as C8F 17EO20), a nonionic fluorocarbon surfactant in an aqueous system, has been investigated by the small-angle X-ray scattering (SAXS) technique. The C8F17EO20 forms micelles and different liquid crystal phases depending on the temperature and composition. The fluorocarbon micellar structure induced by temperature or composition change and added fluorocarbon cosurfactant has been systematically studied. The SAXS data were analyzed by the indirect Fourier transformation (IFT) and the generalized indirect Fourier transformation (GIFT) depending on the volume fraction of the surfactant and complemented by plausible model calculations. The C8F17EO20 forms spherical type micelles above critical micelle concentration (cmc) in the dilute region. The micelle tends to grow with temperature; however, the growth is not significant on changing temperature from 15-75 degrees C, which is attributed to the higher clouding temperature of the surfactant (>100 degrees C). On the other hand, the micellar structure (shape and size) is apparently unaffected by composition (1-25 wt %) at 25 degrees C. Nevertheless, addition of fluorocarbon cosurfactant of structure C8F17SO2N(C3H7)(CH2CH2O)H (abbreviated as C8F17EO1) to the semidilute solution of C8F17EO20 (25 wt %) favors micellar growth, which finally leads to the formation of viscoelastic wormlike micelles, as confirmed by rheometry and supported by SAXS. The onset sphere-to-wormlike transition in the structure of micelles in the C8F17EO20/water/C8F17EO1 system is due to the fact that the C8F17EO1 tends to go to the surfactant palisade layer so that the critical packing parameter increases due to a decrease in the effective cross-sectional area of the headgroup. As a result, spherical micelles grow into a cylinder, which after a certain concentration entangle to form a rigid network structure of wormlike micelles. PMID:18671427

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

2008-08-28

71

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

SciTech Connect

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

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

2014-05-04

72

Adhesion and patterning of cortical neurons on polyethylenimine- and fluorocarbon-coated surfaces.  

PubMed

Adhesion and patterning of cortical neurons was investigated on isolated islands of neuron-adhesive polyethylenimine (PEI) surrounded by a neuron-repellent fluorocarbon (FC) layer. In addition, the development of fasciculated neurites between the PEI-coated areas was studied over a time period of fifteen days. The patterns consisted of PEI-coated wells (diameter 150 microns, depth 0.5 micron) which were etched in a coating of fluorocarbon (FC) on top of polyimide (PI) coated glass. The separation distance between the PEI-coated wells were varied between 10 and 90 microns. This paper shows that chemical patterns of PEI and FC result in highly compliant patterns of adhering cortical neurons after one day in vitro. Interconnecting neurite fascicles between PEI-coated wells were especially present on patterns with a separation distance of 10 microns after eight days in vitro. A significant lower number of interconnecting neurite fascicles was observed on 20 microns separated patterns. Effective isolation of neurons into PEI-coated wells was achieved on patterns with a separation distance of 80 microns as no interconnecting neurite fascicles were observed. PMID:11125594

Ruardij, T G; Goedbloed, M H; Rutten, W L

2000-12-01

73

Application of quantum cascade laser absorption spectroscopy to studies of fluorocarbon molecules  

NASA Astrophysics Data System (ADS)

The recent advent of quantum cascade lasers (QCLs) enables room-temperature mid-infrared spectrometer operation which is particularly favourable for industrial process monitoring and control, i.e. the detection of transient and stable molecular species. Conversely, fluorocarbon containing radio-frequency discharges are of special interest for plasma etching and deposition as well as for fundamental studies on gas phase and plasma surface reactions. The application of QCL absorption spectroscopy to such low pressure plasmas is typically hampered by non-linear effects connected with the pulsed mode of the lasers. Nevertheless, adequate calibration can eliminate such effects, especially in the case of complex spectra where single line parameters are not available. In order to facilitate measurements in fluorocarbon plasmas, studies on complex spectra of CF4 and C3F8 at 7.86 ?m (1269 - 1275 cm-1) under low pressure conditions have been performed. The intra-pulse mode, i.e. pulses of up to 300 ns, was applied yielding highly resolved spectral scans of ~ 1 cm-1 coverage. Effective absorption cross sections were determined and their temperature dependence was studied in the relevant range up to 400 K and found to be non-negligible.

Welzel, S.; Stepanov, S.; Meichsner, J.; Röpcke, J.

2009-03-01

74

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

75

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

SciTech Connect

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

Lee, P.A.; Sylvia, A.L.; Piantadosi, C.A. (Duke Univ. Medical Center, Durham, NC (USA))

1988-04-01

76

Synthesis, Thermal Properties and Cytotoxicity Evaluation of Hydrocarbon and Fluorocarbon Alkyl ?-D-xylopyranoside Surfactants  

PubMed Central

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

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

2011-01-01

77

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

78

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

NASA Technical Reports Server (NTRS)

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

Molina, Mario J.

1990-01-01

79

Development of fluorocarbon evaporative cooling recirculators and controls for the ATLAS inner silicon tracker  

E-print Network

We report on the development of evaporative fluorocarbon cooling recirculators and their control systems for the ATLAS inner silicon tracker. We have developed a prototype circulator using a dry, hermetic compressor with C/sub 3/F/sup 8/ refrigerant, and have prototyped the remote-control analog pneumatic links for the regulation of coolant mass flows and operating temperatures that will be necessary in the magnetic field and radiation environment around ATLAS. pressure and flow measurement and control use 150+ channels of standard ATLAS LMB ("Local Monitor Board") DAQ and DACs on a multi-drop CAN network administered through a BridgeVIEW user interface. A hardwired thermal interlock system has been developed to cut power to individual silicon modules should their temperatures exceed safe values. Highly satisfactory performance of the circulator under steady state, partial-load and transient conditions was seen, with proportional fluid flow tuned to varying circuit power. Future developments, including a 6 kW...

Bayer, C; Bonneau, P; Bosteels, Michel; Burckhart, H J; Cragg, D; English, R; Hallewell, G D; Hallgren, Björn I; Ilie, S; Kersten, S; Kind, P; Langedrag, K; Lindsay, S; Merkel, M; Stapnes, Steinar; Thadome, J; Vacek, V

2000-01-01

80

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

PubMed Central

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

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

2014-01-01

81

ToF-SIMS and AFM studies of low- k dielectric etching in fluorocarbon plasmas  

NASA Astrophysics Data System (ADS)

Surface modifications and etching mechanisms of several nanoporous low- k dielectrics (spin-on and PECVD) using fluorocarbon plasmas have been investigated by ToF-SIMS and AFM and compared with those of SiO 2. The results show a fluoropolymer film growing on the materials using highly polymerizing discharges (C 4F 8). The fluoropolymers are converted into fluoroether-like compounds upon etching low-porosity dielectrics in ion-rich C 4F 8/90% Ar plasmas. These layers mitigate the influx of plasma species and inhibit the etching rate. No surface roughness develops for these conditions, keeping the plasma/material interaction regime stationary. On the other hand, the surface coverage by fluoroethers is reduced when the porosity exceeds a given threshold. Consequently, direct plasma/dielectric interactions including ion bombardment take place, causing an increase of the etching rate, surface roughening and severe modifications of the pristine dielectric.

Lazzeri, P.; Hua, X.; Oehrlein, G.; Iacob, E.; Barozzi, M.; Bersani, M.; Anderle, M.

2006-07-01

82

Correlation of elastohydrodynamic film thickness measurements for fluorocarbon type 2 ester, and polyphenyl ether lubricants  

NASA Technical Reports Server (NTRS)

A minimum films thickness correlation applicable to heavily loaded elastohydrodynamic (EHD) contacts was formulated from experimental data obtained by an X-ray transmission technique. The correlation, based on data generated with fluorocarbon, type II ester, and polyphenyl ether lubricants, extends a previous analysis developed from data for a synthetic paraffinic oil. The resulting correlation represents the data of the four lubricants reasonably well over a large range of operating conditions. Contained within the derived relation is a factor to account for the high-load dependence displayed by the measurements beyond that which is provided for by the theory. Thermal corrections applied to a commonly used film thickness formula showed little improvement to the general disagreement that exists between theory and test. Choice of contact geometry and material are judged to have a relatively mild influence on the form of the semiempirical model.

Loewenthal, S. H.; Parker, R. J.; Zaretsky, E. V.

1974-01-01

83

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

PubMed

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

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

2014-04-01

84

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

85

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

86

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

87

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

SciTech Connect

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

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

2010-01-01

88

Mechanism for the selective etch of silicon dioxide in a high-density, low-pressure, inductively coupled fluorocarbon plasma  

NASA Astrophysics Data System (ADS)

A novel, end launched, m=0 mode helicon wave was developed through the application of an axial magnetic field to a flat, spiral coil, inductively coupled plasma source. The rf magnetic field structure in the plasma was determined with induction probes and shown to match the theory of an m=0 helicon wave. Helicon wave power deposition, determined from axial damping of the helicon wave, agreed with theory within a factor of two. Fluorocarbon film deposition was studied in inductively coupled and helicon plasmas. Polymer growth rates were modeled as a function of the fluorocarbon radical densities, measured with wavelength modulated infrared diode laser absorption spectroscopy, F concentration, determined using actinometric optical emission spectroscopy, and ion current density, monitored with a Langmuir probe. The resulting quantitative model reveals the polymer growth mechanism is a combination of direct incorporation of CF and ion-assisted CF2 deposition. Decreased wafer temperature and increased chamber temperature increased polymer deposition rates. Absolute temperatures were not important and the role of temperature on the polymer growth can be characterized by the relative temperature difference between chamber and wafer. Fluorocarbon plasma chemistry variation was observed as a stainless steel surface, within the chamber, increased in temperature. Reduced fluorine and hydrogen atom densities accompanied increased CF2 and decreased CF radical concentrations. Chemistry changes with surface temperature were only observed if the feed gas contained hydrogen. Fluorine and hydrogen losses were determined to be first order. No variation without hydrogen and first order losses for fluorine and hydrogen suggests surface combination to form HF. Patterned SiO2 wafers were etched to investigate etch rate and photoresist selectivity mechanisms. Etch rates and selectivities exhibited an inverse relationship with higher selectivities coming at a loss of etch rate. Etch results have been analyzed with a heuristic model wherein photoresist and SiO2 etch rates were determined by energetic ion bombardment inhibited by a steady-state fluorocarbon film. Due to an ion bombardment induced reaction between the fluorocarbon polymer and the SiO2, a thinner film forms on the SiO2 relative the photoresist. All selectivity can be attributed to a thinner steady-state fluorocarbon film on the SiO 2.

Sowa, Mark Justin

1999-11-01

89

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

PubMed

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

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

2014-05-01

90

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

Microsoft Academic Search

Fluorocarbon (FC) plasmas are commonly used for dielectric materials etching. Our initial work was performed using an inductively coupled plasma (ICP) system to produce FC discharges. We first examined the effect of CO addition to C4F8 or C4F8\\/Ar plasmas for selective etching of organosilicate glass (OSG), which is a typical low k (LK) material over etch stop layers. The chemical

Li Ling

2006-01-01

91

Anisotropic fluorocarbon plasma etching of silicon\\/silicon germanide heterostructures and plasma etching-induced sidewall damage  

Microsoft Academic Search

Plasma etching is a critical tool in the fabrication of Si\\/SiGe heterostructure quantum devices, but with challenges addressed herein, including (1) control of etch profiles and (2) damage to etched feature sidewalls that affects device performance. (1) Fluorocarbon-based plasma etching often results in device profiles with undercuts due to preferential etching of SiGe over silicon. A C4F8\\/N2\\/Ar etch plasma gas

Ruhang Ding

2008-01-01

92

Behavior of clathrate hydrate formation at the boundary of liquid water and a fluorocarbon in liquid or vapor state  

Microsoft Academic Search

Observational studies have been carried out to reveal the mechanistic aspects of the formation of clathrate hydrate, crystalline solid, at the boundary of water in the liquid state and a fluorocarbon (HFC-134a; CF3CH2F) in the liquid or vapor state. The surface morphology of the hydrate layer formed at the interface depends strongly on the degree of saturation of the water

Makoto Sugaya; Yasuhiko H. Mori

1996-01-01

93

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

PubMed

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; Jahnen-Dechent, Willi

2013-10-01

94

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

95

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

96

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

97

Mid-infrared chemical sensors utilizing plasma-deposited fluorocarbon membranes.  

PubMed

In this study, plasma-polymerized films are evaluated as enrichment membranes deposited at the surface of mid-infrared transparent waveguides for liquid-phase chemical sensing utilizing evanescent field absorption spectroscopy. Fluorocarbon films were deposited onto zinc selenide (ZnSe) waveguides from plasma-polymerized pentafluoroethane (CF(3)CHF(2)) vapor. Excellent optical transmission of ZnSe waveguides after plasma deposition confirms compatibility of the infrared transparent substrate with this low-temperature, solvent-free film deposition process. The liquid-phase enrichment characteristics for plasma membranes were investigated via evanescent field absorption spectroscopy of a model analyte (tetrachloroethylene); the limits of detection were below 300 ppb (v/v) in water. Plasma-polymerized films are known for their excellent mechanical and chemical stability, while offering tunable chemical and physical characteristics during the deposition process. Future application of this coating strategy for depositing robust enrichment membranes with tunable batch production capability imparts an attractive route toward application-oriented development of next-generation mid-infrared chemical sensors applicable in harsh environments. PMID:18020310

Dobbs, Gary T; Balu, Balamurali; Young, Christina; Kranz, Christine; Hess, Dennis W; Mizaikoff, Boris

2007-12-15

98

Vascular perfusion of the isolated rat stomach with a fluorocarbon emulsion.  

PubMed Central

A constant-pressure system using a fluorocarbon (FC-75) containing artificial medium was used for vascular perfusion of the isolated rat stomach. A 10% emulsion of FC-75 in a modified Tyrode solution, containing 3.5% bovine serum albumin, amino acids, nucleosides, and beta-hydroxybutyrate appeared to allow an adequate perfusion for at least seven hours. The following criteria were used to estimate for functional state of the perfused stomach: (1) venous flow, (2) oxygen consumption, (3) leakage from the blood vessels to the gastric lumen, (4) ultrastructure, (5) secretion of H+ and pepsinogen after stimulation, and (6) transport of labelled macromolecules. During perfusion oxygen consumption and venous flow remained, after an initial high value, constant for at least seven hours. Leakage from the vascular bed was absent. Ultrastructure was preserved for at least seven hours. Administration of pilocarpine led to secretion of HCl ad pepsinogen. Pentagastrin and histamine stimulated HCl secretion in only some of the preparations. [3H]-galactose was incorporated into macromolecules and transported from the Golgi-region towards the apex of the cell. These observations led to the conclusion that the described vascular perfusion system in at least an appropriate model for studying glycoprotein synthesis. PMID:7297918

Van Huis, G A; Kramer, M F

1981-01-01

99

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

NASA Astrophysics Data System (ADS)

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

Banik, Indranil; Bhowmick, Anil K.

1999-01-01

100

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

SciTech Connect

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

Branch, C.A.; Goldberg, D.A.; Ewing, J.R.; Butt, S.S.; Gayner, J. [Henry Ford Hospital, Detroit, MI (United States); Fagan, S.C. [Wayne State Univ., Detroit, MI (United States)

1994-12-31

101

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

SciTech Connect

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

NIGREY,PAUL J.; BOLTON,DENNIS L.

2000-02-01

102

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

SciTech Connect

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

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

1992-12-31

103

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

SciTech Connect

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

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

1992-01-01

104

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

SciTech Connect

The present work focuses on the plasma deposition of fluorocarbon (FC) films on surfaces and the electrostatic control of their wettability (electrowetting). Such films can be employed for actuation of fluid transport in microfluidic devices, when deposited over patterned electrodes. Here, the deposition was performed using C{sub 4}F{sub 8} and the plasma parameters that permit the creation of films with optimized properties desirable for electrowetting were established. The wettability of the plasma-deposited surfaces was characterized by means of contact angle measurements (in the static and dynamic mode). The thickness of the deposited films was probed in situ by means of spectroscopic ellipsometry, while the surface roughness was provided by atomic force microscopy. These plasma-deposited FC films in combination with silicon nitride, a material of high dielectric constant, were used to create a dielectric structure that requires reduced voltages for successful electrowetting. Electrowetting experiments using protein solutions were conducted on such optimized dielectric structures and were compared with similar structures bearing commercial spin-coated Teflon registered amorphous fluoropolymer (AF) film as the hydrophobic top layer. Our results show that plasma-deposited FC films have desirable electrowetting behavior and minimal protein adsorption, a requirement for successful transport of biological solutions in 'digital' microfluidics.

Bayiati, P.; Tserepi, A.; Petrou, P. S.; Kakabakos, S. E.; Misiakos, K.; Gogolides, E. [Institute of Microelectronics-NCSR 'Demokritos', POB 60228, 153 10 Aghia Paraskevi, Attiki (Greece); Institute of Radioisotopes and Radiodiagnostic Products-NCSR 'Demokritos', POB 60228, 153 10 Aghia Paraskevi, Attiki (Greece); Institute of Microelectronics-NCSR 'Demokritos', POB 60228, 153 10 Aghia Paraskevi, Attiki (Greece)

2007-05-15

105

Global warming implications of non-fluorocarbon technologies as CFC replacements  

SciTech Connect

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

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

1993-12-31

106

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

107

Temperature-dependent electron capture detector response to common alternative fluorocarbons.  

PubMed

The relative electron capture detector (ECD) response to alternative fluorocarbons (AFCs) using gas chromatography are found to be at least 1 order of magnitude lower than that for CFC-12. Detection limits for the chlorofluorocarbons CFC-12, HCFC-22, HCFC-123, and HCFC-124 are found to be 2.5, 90, 30, and 90 pg, respectively. Those for the hydrofluorocarbons are significantly poorer; 14 and 45 ng for HFC-125 and HFC-134a, respectively. HFC-152a was not detected using ECD. Since atmospheric concentrations of these compounds are in the low part-per-trillion level, GC-ECD is apparently not sensitive enough to be used for AFC analysis without substantial preconcentration. Two columns are evaluated for the AFC separation. The Poraplot Q WPLOT column showed good separation ability, though column bleed limits detection performance. A Carboxen 1004 packed column exhibits much lower interference. But separations are time consuming and peak broadening adversely affects limits of detection. Mechanisms for the ECD response are proposed based on thermodynamics and temperature-dependent ECD responses. CFC-12, HCFC-123, and HFC-125 apparently undergo ion-forming dissociative electron capture. The electron capture process for HCFC-22 and HFC-134a appear to form molecular ions. Both mechanisms appear to be operative for HCFC-124 electron capture. Dissociative electron capture rate constants for HCFC-123, HCFC-124, and HFC-125 are estimated to be 3.5 × 10(-)(10), 1.0 × 10(-)(10), and 5.6 × 10(-)(13) cm(3) s(-)(1), respectively at 300 °C. PMID:21639206

Sousa, S R; Bialkowski, S E

1997-10-01

108

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

NASA Technical Reports Server (NTRS)

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

Zellner, Reinhard

1990-01-01

109

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

NASA Astrophysics Data System (ADS)

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

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

110

UV-Assisted Modification and Removal Mechanism of a Fluorocarbon Polymer Film on Low-k Dielectric Trench Structure.  

PubMed

In this study, we report the first chemical characterization of a plasma-deposited model fluoropolymer on low-k dielectric nanostructure and its decomposition in UV/O2 conditions. Carbonyl incorporation and progressive removal of fluorocarbon fragments from the polymer were observed with increasing UV (?230 nm) irradiation under atmospheric conditions. A significant material loss was achieved after 300 s of UV treatment and a subsequent wet clean completely removed the initially insoluble fluoropolymer from the patterned nanostructures. A synergistic mechanism of UV light absorption by carbonyl chromophore and oxygen incorporation is proposed to account for the observed photodegradation of the fluoropolymer. PMID:25679964

Mukherjee, Tamal; Berhe, Seare A; Goswami, Arindom; Chyan, Oliver; Singh, Kanwal Jit; Brown, Ian

2015-03-11

111

Anisotropic fluorocarbon plasma etching of silicon/silicon germanide heterostructures and plasma etching-induced sidewall damage  

NASA Astrophysics Data System (ADS)

Plasma etching is a critical tool in the fabrication of Si/SiGe heterostructure quantum devices, but with challenges addressed herein, including (1) control of etch profiles and (2) damage to etched feature sidewalls that affects device performance. (1) Fluorocarbon-based plasma etching often results in device profiles with undercuts due to preferential etching of SiGe over silicon. A C4F8/N2/Ar etch plasma gas mixture introduced here has been successfully used to achieve straight sidewalls through heterostructure layers by formation of a fluorocarbon inhibitor film on feature sidewalls to prevent undercutting. (2) Chemical and structural changes in the semiconductor at feature sidewalls associated with plasma-surface interactions are considered damage, as they affect band structure and electrical conduction in the active region of the device, known as the 2-dimensional electron gas (2DEG). In experiments designed to better understand the mechanisms of plasma-induced sidewall damage, damage to straight wires was characterized both by the width of a non-conductive "sidewall depletion" region at the device sidewall, and by the noise level factor, gamma H/N, determined from spectra of low frequency noise. Observed increases in sidewall depletion width with increasing etch depth are tentatively attributed to the increase in total number of defects with increased plasma exposure time. Excess negative charge incorporated into the fluorocarbon inhibitor film could be another contributing factor. Other factors considered, including defects at the bottom of etched features as well as leakage current bypassing the wire, are ruled out as their contribution is expected to diminish as the distance between the 2DEG and feature bottom increases. The noise level factor, gammaH /N, shows a maximum with increasing etch depth, possibly the result of two competing effects: increasing ion dose and decreasing leakage current. The noise level shows a minimum at an ion bombardment energy of ˜100 eV, while the sidewall depletion width is independent of bias voltage, within experimental uncertainty. A proposed explanation of the noise trend involves two competing effects as ion energy increases: the increase in damage caused by each bombarding ion and the reduction in total ion dose due to shorter etch times and reduced ion flux to the sidewalls.

Ding, Ruhang

112

Comparison of pulsed and downstream deposition of fluorocarbon materials from C3F8 and cC4F8 plasmas  

Microsoft Academic Search

Materials deposited in continuous wave (cw) and pulsed low-pressure octafluoropropane (C3F8) and octafluorocyclobutane (c-C4F8) plasmas were characterized using Fourier transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy, static contact angle measurements, spectroscopic ellipsometry, and scanning electron microscopy (SEM). Fluorocarbon (FC) materials deposited in pulsed plasmas were less crosslinked than those deposited in cw plasmas with equivalent input powers. Within each system,

Ina T. Martin; Galiya Sh. Malkov; Carmen I. Butoi; Ellen R. Fisher

2004-01-01

113

Plasma-deposited fluorocarbon films: insulation material for microelectrodes and combined atomic force microscopy-scanning electrochemical microscopy probes.  

PubMed

Pinhole-free insulation of micro- and nanoelectrodes is the key to successful microelectrochemical experiments performed in vivo or in combination with scanning probe experiments. A novel insulation technique based on fluorocarbon insulation layers deposited from pentafluoroethane (PFE, CF3CHF2) plasmas is presented as a promising electrical insulation approach for microelectrodes and combined atomic force microscopy-scanning electrochemical microscopy (AFM-SECM) probes. The deposition allows reproducible and uniform coating, which is essential for many analytical applications of micro- and nanoelectrodes such as, e.g., in vivo experiments and SECM experiments. Disk-shaped microelectrodes and frame-shaped AFM tip-integrated electrodes have been fabricated by postinsulation focused ion beam (FIB) milling. The thin insulation layer for combined AFM-SECM probes renders this fabrication technique particularly useful for submicro insulation providing radius ratios of the outer insulation versus the disk electrode (RG values) suitable for SECM experiments. Characterization of PFE-insulated AFM-SECM probes will be presented along with combined AFM-SECM approach curves and imaging. PMID:18510344

Wiedemair, Justyna; Balu, Balamurali; Moon, Jong-Seok; Hess, Dennis W; Mizaikoff, Boris; Kranz, Christine

2008-07-01

114

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

NASA Astrophysics Data System (ADS)

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

Zandona, Philip

115

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

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

116

Contributions of CF and CF2 Species to fluorocarbon film composition and properties for C(x)F(y) plasma-enhanced chemical vapor deposition.  

PubMed

Inductively-coupled C(x)F(y) (y/x = 2.0-4.0) plasma systems were investigated to determine relationships between precursor chemistry, CF(n) radical-surface reactivities, and surface properties of deposited films. The contributions of CF(n) (n = 1, 2) radicals to film properties were probed via gas-phase diagnostics and the imaging of radicals interacting with surfaces (IRIS) technique. Time-resolved radical emission data elucidate CF(g) and CF(2)(g) production kinetics from the C(x)F(y) source gases and demonstrate that CF(4) plasmas inherently lag in efficacy of film formation when compared to C(2)F(6), C(3)F(8), and C(3)F(6) systems. IRIS data show that as the precursor y/x ratio decreases, the propensity for CF(n) scatter concomitantly declines. Analyses of the composition and characteristics of fluorocarbon films deposited on Si wafers demonstrate that surface energies of the films decrease markedly with increasing film fluorine content. In turn, increased surface energies correspond with significant decreases in the observed scatter coefficients for both CF and CF(2). These data improve our molecular-level understanding of CF(n) contributions to fluorocarbon film deposition, which promises advancements in the ability to tailor FC films to specific applications. PMID:22364290

Cuddy, Michael F; Fisher, Ellen R

2012-03-01

117

Comparison of pulsed and downstream deposition of fluorocarbon materials from C3F8 and c-C4F8 plasmas  

NASA Astrophysics Data System (ADS)

Materials deposited in continuous wave (cw) and pulsed low-pressure octafluoropropane (C3F8) and octafluorocyclobutane (c-C4F8) plasmas were characterized using Fourier transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy, static contact angle measurements, spectroscopic ellipsometry, and scanning electron microscopy (SEM). Fluorocarbon (FC) materials deposited in pulsed plasmas were less crosslinked than those deposited in cw plasmas with equivalent input powers. Within each system, higher F/C ratio materials were deposited by lowering the plasma input power/duty cycle. Using downstream depositions had a similar effect on film composition, but also resulted in decreased deposition rates. SEM analysis showed that decreases in the flexibility of the fluorocarbon films were correlated with increases in the percent of crosslinking. Additionally, the smoothness of the film surfaces suggests that polymerization processes occur on the substrate surface. Overall, films deposited in C4F8 plasmas were more crosslinked and less flexible than those deposited in C3F8 plasmas under the same conditions. The composition of the deposited FC films is correlated to the nature and relative concentrations of nascent ions previously measured in these plasma systems using plasma ion mass spectrometry. .

Martin, Ina T.; Malkov, Galiya Sh.; Butoi, Carmen I.; Fisher, Ellen R.

2004-03-01

118

Fluorocarbon assisted atomic layer etching of SiO{sub 2} using cyclic Ar/C{sub 4}F{sub 8} plasma  

SciTech Connect

The authors demonstrate atomic layer etching of SiO{sub 2} using a steady-state Ar plasma, periodic injection of a defined number of C{sub 4}F{sub 8} molecules, and synchronized plasma-based Ar{sup +} ion bombardment. C{sub 4}F{sub 8} injection enables control of the deposited fluorocarbon (FC) layer thickness in the one to several Ångstrom range and chemical modification of the SiO{sub 2} surface. For low energy Ar{sup +} ion bombardment conditions, the physical sputter rate of SiO{sub 2} vanishes, whereas SiO{sub 2} can be etched when FC reactants are present at the surface. The authors have measured for the first time the temporal variation of the chemically enhanced etch rate of SiO{sub 2} for Ar{sup +} ion energies below 30?eV as a function of fluorocarbon surface coverage. This approach enables controlled removal of Ångstrom-thick SiO{sub 2} layers. Our results demonstrate that development of atomic layer etching processes even for complex materials is feasible.

Metzler, Dominik; Oehrlein, Gottlieb S., E-mail: oehrlein@umd.edu [Department of Material Science and Engineering, Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States); Bruce, Robert L.; Engelmann, Sebastian; Joseph, Eric A. [IBM T.J. Watson Research Center, Yorktown Heights, New York 10598 (United States)

2014-03-15

119

High density fluorocarbon plasma etching of methylsilsesquioxane SiOC(H) low-k material and SiC(H) etch stop layer: surface analyses and investigation of etch mechanisms  

NASA Astrophysics Data System (ADS)

This paper focuses on plasma etching and XPS surface analyses of new dielectric materials used in integrated circuits. We investigate by XPS surface modifications of methylsilsesquioxane low-k polymer (SiOC(H)) and amorphous hydrogenated silicon carbide (SiC(H)) when exposed to Ar, SF6 and C2F6-based high density plasmas. Ar and SF6 plasmas remove the carbonaceous groups from the surface leading to the formation of fluorinated top layers (SiOF and SiF-like layers) in SF6 plasma. In the case of C2F6-based mixtures, the surface structure fits well with a two-layer model, consisting of a fluorocarbon top layer above a fluorinated interaction layer (SiOF or SiF) on the bulk materials (SiOC(H) or SiC(H)). Determination of top layer thicknesses from XPS data is discussed. We show that material etch rate is not correlated with the total modified thickness, in contrast to the top fluorocarbon layer thickness which is in good correlation with etch rates. Etch yields (etch rates divided by the ion flux) are calculated and are studied in order to draw material etch mechanisms in C2F6 based mixtures. We conclude that for both materials, etching mechanisms in C2F6/H2 mixtures, and to a lesser extent in C2F6/Ar mixtures, are close to those of silicon in fluorocarbon plasmas and different from those of the conventional interlevel dielectric material SiO2. On the contrary etching mechanisms in C2F6/O2 mixtures are similar to those of silicon dioxide in fluorocarbon plasmas.

Eon, D.; Raballand, V.; Cartry, G.; Cardinaud, C.

2007-07-01

120

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

SciTech Connect

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

Bai Bo; Sawin, Herbert H.; Cruden, Brett A. [Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Department of Chemical Engineering and Electrical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); NASA Ames Center for Nanotechnology, Moffett Field, California 94035 (United States)

2006-01-01

121

Comparison of CH, C3, CHF, and CF2 surface reactivities during plasma-enhanced chemical vapor deposition of fluorocarbon films.  

PubMed

The overall character of films deposited using plasma-enhanced chemical vapor deposition relies on the interactions of gas-phase molecules with the depositing film surface. The steady-state surface interactions of CH, C3, CHF, and CF2 have been characterized at the interface of depositing fluorocarbon (FC) films using the imaging of radicals interacting with surfaces (IRIS) technique. IRIS measurements show that the relative gas-phase densities of CH, C3, CHF, and CF2 in mixed FC plasmas depend on the CH2F2/C3F8 ratio. Similar results are found using optical emission spectroscopy to monitor the production of excited-state plasma species. The effects of plasma parameters, such as the feed gas composition and substrate bias on the radical surface, were measured. Under all conditions, the surface reactivity for CH radicals is near unity, whereas those for C3, CHF, and CF2 exhibit very low surface reactivity but also show some dependence on experimental parameters. Under some conditions, CF2 and CHF are generated at the surface of the depositing film. Surface reactivity measurements indicate that CF2, CHF, and C3 may contribute to FC growth only when adsorbing at reactive sites at the film surface. Moreover, the low surface reactivities of singlet species such as C3, CF2, and CHF may be related to the electronic configuration of the molecules. PMID:20356020

Liu, Dongping; Cuddy, Michael F; Fisher, Ellen R

2009-04-01

122

Evaluation of a mirror-polishing technique for fluorocarbon polymer surfaces for reduction of contamination from containers used in ultratrace analysis.  

PubMed

A mirror-polishing technique for fluorocarbon polymer surfaces using high-precision diamond cutting tools was developed. The goal of this technique was the reduction of ultratrace elemental analysis contamination levels of containers fabricated from such mirror-polished materials. Remarkably smooth inner surfaces with degrees of flatness of 0.1 ?m peak-to-valley (PTV) for containers fabricated from mirror-polished PTFE materials were obtained, in contrast to degrees of surface flatness of more than 30 ?m PTV for commercially available PTFE containers. (Here, PTV denotes the difference between the highest peak and deepest valley in a scanned area of 10 × 10 ?m.) Extractable impurity levels for mirror-polished PTFE container surfaces were reduced by more than 1 order of magnitude relative to those of unpolished PTFE containers. The surface conditions of the PTFE containers were observed by atomic force and scanning electron microscopy. The microphotographs so obtained suggest that the degree of surface smoothness of the containers is proportional to their ultratrace metallic contamination levels. PMID:21639235

Takenaka, M; Hayashi, M; Suzuki, I; Yamada, Y; Takamatsu, K; Kageyama, M

1997-03-01

123

Plasma deposition of fluorocarbon thin films from c-C{sub 4}F{sub 8} using pulsed and continuous rf excitation  

SciTech Connect

Fluorocarbon films of varying composition have been deposited from pulsed and continuous plasmas of octafluorocyclobutane (c-C{sub 4}F{sub 8}) and c-C{sub 4}F{sub 8}/Ar. Continuous plasma deposition rates are a very weak function of applied rf power (may be within experimental error). Pulsed plasma deposition rates are significantly lower than continuous plasma rates at the same average power. The pulsed plasma deposition rates can be attributed almost entirely to the plasma on time during the pulse, but there is a slight dependence on pulse off time. Ar addition affects the deposition rates through a residence time effect, but also affects the deposition chemistry by reducing the degree of C{sub 4}F{sub 8} dissociation, resulting in more fluorinated films. Refractive indices for all films increase approximately linearly with applied rf power, with the pulsed plasma-deposited films falling on the same curve. Carbon 1s x-ray photoelectron spectroscopy shows that the continuous plasma-deposited films become increasingly fluorinated as the rf power is decreased. Pulsed plasma films are more fluorinated than similar average power continuous plasma films: 44% CF{sub 2} for 10/50 (400 W on time, 67 W average power) versus 37% for 50 W continuous. Literature and preliminary gas-phase measurements suggest that the C{sub 4}F{sub 8} is not fully dissociated in either plasma system and that larger species in the gas phase may play a significant role in the deposition mechanisms.

Labelle, Catherine B.; Opila, Robert; Kornblit, Avi [Lucent Technologies Bell Labs, 600 Mountain Avenue, Murray Hill, New Jersey 07974 (United States)

2005-01-01

124

Rayleigh scattering measurements of several fluorocarbon gases.  

PubMed

Integrating nephelometers are commonly used to monitor airborne particulate matter. However, they must be calibrated prior to use. The Rayleigh scattering coefficients (b(RS), Mm(-1)), scattering cross sections (?(RS), cm(2)), and Rayleigh multipliers for tetrafluoromethane (R-14), sulfur hexafluoride, pentafluoroethane (HFC-125), hexafluoropropene (HFC-216), 1,1,1,2,3,3,3,-heptafluoropropane (HFC-227ea), and octafluorocyclobutane (C-318) are reported from measurements made using a Radiance Research M903 integrating nephelometer operating at ? = 530 nm and calibration with gases of known scattering constants. Rayleigh multipliers (±90% conf. int.) were found to be 2.6 ± 0.5, 6.60 ± 0.07, 7.5 ± 1, 14.8 ± 0.9, 15.6 ± 0.5, and 22.3 ± 0.8 times that of air, respectively. To the best of our knowledge, these are the first reported values for R-14, HFC-216, HFC-125, and C-318. Experimental accuracy is supported through measurements of values for SF(6) and HFC-227ea which agree to within 3% of previous literature reports. In addition to documenting fundamental Rayleigh scattering data for the first time, the information presented within will find use for calibration of optical scattering sensors such as integrating nephelometers. PMID:22027960

Zadoo, Serena; Thompson, Jonathan E

2011-11-01

125

21 CFR 177.1380 - Fluorocarbon resins.  

Code of Federal Regulations, 2010 CFR

...accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from the American Society for Testing and Materials, 1916 Race St., Philadelphia, PA 19013, or may be examined at the National Archives and Records...

2010-04-01

126

21 CFR 177.1380 - Fluorocarbon resins.  

Code of Federal Regulations, 2014 CFR

...accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from the American Society for Testing and Materials, 1916 Race St., Philadelphia, PA 19013, or may be examined at the National Archives and Records...

2014-04-01

127

21 CFR 177.1380 - Fluorocarbon resins.  

Code of Federal Regulations, 2011 CFR

...accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from the American Society for Testing and Materials, 1916 Race St., Philadelphia, PA 19013, or may be examined at the National Archives and Records...

2011-04-01

128

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

129

Use of fluorocarbons in the cooling of LHC experiments  

E-print Network

Perfluorochemicals sold by 3M under the trade name 3M Fluorinert Electronic Liquids have been used for many years as heat transfer media in a variety of industries. The suitability of these liquids for the cooling of LHC experiment originates from their high dielectric strength as well as from their chemical stability under ionizing radiation. The Fluorinerts are clear, colorless, non-flammable with low toxicity and low corrosiveness. Additionally, they offer low global waming potential – GWP – and zero ozone-depletion potential – ODP. Some examples of fluorinert application in the cooling of LHC experiments will be presented : (a) the ATLAS Inner detector C3F8 evaporative cooling system (b) the ATLAS TRF C6F14 monophase cooling system and (c) the ALICE SPD “active heat pipe” C4F10 evaporative cooling system. A brief comparison of evaporative and monophase cooling systems will be outlined.

Pimenta dos Santos, M

2003-01-01

130

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

131

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

132

Interaction of 157-nm excimer laser radiation with fluorocarbon polymers  

NASA Astrophysics Data System (ADS)

Two important fluoropolymers, polytetrafluoroethylene [PTFE—(C 2F 4) N] and polyvinylidene fluoride [PVDF—(C 2H 2F 2) N], respond to 157-nm laser radiation in dramatically different ways. At fluences sufficient to produce rapid etching, the volatile emissions from PTFE are dominated by (CF 2) N fragments. The velocities of the fastest (CF 2) N molecules at each mass are consistent with kinetic energies on the order of an electron volt—and change little with fluence. This fluence independence suggests that the velocities are not affected by collisions after emission. To account for the high kinetic energies and the unusual, half-monomer mass distribution, we propose that these fragments are produced by photochemical scission of the polymer backbone, and that a fraction of the excitation energy is delivered to each fragment as kinetic energy. In contrast, the principle neutral species from PVDF is HF. HF is produced by the scission of C-F bonds, followed by chemical reactions with nearby hydrogen. This process is accompanied by the conjugation of backbone C-C bonds. The photochemical cleavage of C-C bonds in PTFE and C-F bonds in PVDF is consistent with the lower C-C bond energy of PTFE.

George, Sharon R.; Leraas, John A.; Langford, Stephen C.; Dickinson, J. T.

2009-09-01

133

Effects of fluorocarbon propellants on respiratory flow and ECG.  

PubMed

Ten subjects were exposed to the propellants freon 11, freon 12, freon 114, to two mixtures of freon 11 and 12 and to a mixture of freon 12 and 114. The length of exposure was 15, 45 or 60 seconds. Maximum expiratory flow-volume (MEF) curves and ECG were recorded before, and intermittently up to 1 hour after, exposure. Breathing level concentrations of propellants during exposure were determined by gas chromatography. All freons induced biphasic reduction of ventilatory capacity on inhalation. The first fall occurred within a few minutes of exposure while the second was delayed 13-30 minutes after exposure. The effects of mixtures were greater than those of individual freons. The relative fall in MEF 75% was more pronounced than that in MEF 50%. No clear-cut pathological changes in ECG were found. Nevertheless, most subjects developed variations in heart rate exceeding those noted before exposure. In a few cases inversion of the T wave, and in one case atrioventricular block, were observed. PMID:871444

Vali?, F; Skuri?, Z; Banti?, Z; Rudar, M; He?ej, M

1977-05-01

134

Role of surface temperature in fluorocarbon plasma-surface interactions  

SciTech Connect

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

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

2012-07-15

135

Attenuation of fluorocarbons released from foam insulation in landfills.  

PubMed

Chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs) have been used as blowing agents (BAs) for foam insulation in home appliances and building materials, which after the end of their useful life are disposed of in landfills. The objective of this project was to evaluate the potential for degradation of BAs in landfills, and to develop a landfill model, which could simulate the fate of BAs in landfills. The investigation was performed by use of anaerobic microcosm studies using different types of organic waste and anaerobic digested sludge as inoculum. The BAs studied were CFC-11, CFC-12, HCFC-141b, HFC-134a, and HFC-245fa. Experiments considering the fate of some of the expected degradations products of CFC-11 and CFC-12 were included like HCFC-21, HCFC-22, HCFC-31, HCFC-32, and HFC-41. Degradation of all studied CFCs and HCFCs was observed regardless the type of waste used. In general, the degradation followed first-order kinetics. CFC-11 was rapidly degraded from 590 microg L(-1) to less than 5 microg L(-1) within 15-20 days. The degradation pattern indicated a sequential production of HCFC-21, HCFC-31, and HFC-41. However, the production of degradation products did not correlate with a stoichiometric removal of CFC-11 indicating that other degradation products were produced. HCFC-21 and HCFC-31 were further degraded whereas no further degradation of HFC-41 was observed. The degradation rate coefficient was directly correlated with the number of chlorine atoms attached to the carbon. The highest degradation rate coefficient was obtained for CFC-11, whereas lower rates were seen for HCFC-21 and HCFC-31. Equivalent results were obtained for CFC-12. HCFC-141b was also degraded with rates comparable to HCFC-21 and CFC-12. Anaerobic degradation of the studied HFCs was not observed in any of the experiments within a run time of up to 200 days. The obtained degradation rate coefficients were used as input for an extended version of an existing landfill fate model incorporating a time dependent BA release from co-disposed foam insulation waste. Predictions with the model indicate that the emission of foam released BAs may be strongly attenuated by microbial degradation reactions. Sensitivity analysis suggests that there is a need for determination of degradation rates under more field realistic scenarios. PMID:18075079

Scheutz, Charlotte; Dote, Yutaka; Fredenslund, Anders M; Mosbaek, Hans; Kjeldsen, Peter

2007-11-15

136

Mixed Micellization Properties of Nonionic Fluorocarbon\\/Cationic Hydrocarbon Surfactants  

Microsoft Academic Search

The physico-chemical properties of mixed surfactant aqueous solutions at various proportions of dodecyltrimethyl ammonium\\u000a bromide DTAB and undecafluoro n-pentyl decaoxyethylene ether C5F11EO10 have been investigated at 25 °C using surface tension and conductivity measurements.\\u000a The critical micelle concentration and superficial minimum tension have been experimentally estimated for different DTAB molar\\u000a fractions. The micellar composition and mutual interaction parameters have been deduced

Hayet BelarbiDalila Bendedouch; Dalila Bendedouch; Farida Bouanani

2010-01-01

137

192 IEEE SENSORS JOURNAL, VOL. 7, NO. 2, FEBRUARY 2007 Hydrocarbon and Fluorocarbon Monitoring by MIS  

E-print Network

by sensors based on Pd-SiO2-Si (MIS) and Pt-LaF3-Si3N4- SiO2-Si (MEIS) structures was achieved based on Pt-LaF3-Si3N4-SiO2-Si (MEIS) and Pd-SiO2-Si (MIS) structures were used. The Pt-LaF3- Si3N4-SiO2-Si structures were prepared using an n-Si/ SiO2 (20 nm)/Si3N4 (80 nm) wafer with a donor

Moritz, Werner

138

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

139

Preferential adsorption of solid monolayers of hydrocarbons over fluorocarbons at the solid/liquid interface  

NASA Astrophysics Data System (ADS)

A novel combination of sensitive calorimetry, neutron diffraction and NMR have been used to investigate the preferential adsorption and phase behaviour of the solid monolayers absorbed onto graphite from binary n-alkane/ n-perfluoroalkane mixtures. The results indicate that the alkane preferentially adsorbs for essentially all mixture compositions to the complete exclusion of the fluoroalkane. The fluoroalkane monolayer is completely displaced from the graphite surface on addition of the equivalent of just 1 ML of alkane to the mixture. The hydrocarbon is preferentially adsorbed both as solid monolayer and as a liquid.

Parker, J. E.; Clarke, S. M.; Perdigón, A. C.

2007-09-01

140

Fluorocarbons as oxygen carriers. II. An NMR study of partially or totally fluorinated alkanes and alkenes  

NASA Astrophysics Data System (ADS)

Highly fluorinated compounds of the general type R F?R H or R F?R H'?R F, with R F: n-C nF 2 n+1 n = 6, 7, or 8; R H: C 2H 5, CH?CH 2, n-C 8H 17; R H': CH?CH, CH 2?CH 2, are studied either as pure degassed liquids or as solvents of oxygen, using 13C relaxation times T 1 measurements in each case. Comparison of the relaxation data for the degassed liquids with those relative to the analogous n-alkanes provides evidence for slower internal segmental motions in the perfluoroalkyl chains. This rate decrease is shown to arise mainly from purely inertial effects and not from increased rotational potential barriers, thus suggesting similar flexibilities of both hydrocarbon and perfluorocarbon chains. Solubilities of oxygen (in mole fractions) are higher in fluoroalkanes than in previously studied hexafluorobenzene (J-J. Delpuech, M. A. Hamza, G. Serratrice, and M. J. Stebe, J. Chem. Phys.70, 2680 (1979)). Relaxation data are expressed by the variation rates qx of relaxation rates T1-1 per mole fraction of dissolved oxygen. Values of qx. roughly decrease with the total length of the aliphatic chains, and from the ends of the center of each chain, except for C 6F 13CH?CHC 6F 13. These results are not consistent with specific attractive oxygen-fluorine forces, the major factor for solubility being the liquid structure of the solvent, mainly determined by the shape of molecules, according to Chandler's viewpoint.

Ali Hamza, M'Hamed; Serratrice, Guy; Stébé, Marie-José; Delpuech, Jean-Jacques

141

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...

142

Stabilization mechanism of TiO 2 on flexible fluorocarbon films as a functional photocatalyst  

Microsoft Academic Search

The repetitive discoloration kinetics of the azo-dye Methyl Orange (taken as a model organic compound) was followed under solar simulated radiation (90mW\\/cm2) to assess the performance of the TiO2\\/Tedlar® composite photocatalyst. The influence of solution parameters on the photo-discoloration process: pH, dye concentration, applied light intensity and concentration of H2O2 were systematically investigated. During the photocatalysis a modification occurs in

Yu Zhiyong; E. Mielczarski; J. A. Mielczarski; D. Laub; L. Kiwi-Minsker; A. Renken; J. Kiwi

2006-01-01

143

Semiconductor sensors for the detection of fluorocarbons, fluorine and hydrogen fluoride  

Microsoft Academic Search

The sensitivity of metal–insulator–semiconductor structure gas sensors based on silicon or silicon carbide to different fluorine-containing gases was studied in the temperature range 20–530°C. Silicon based gas sensors could be used for the determination of fluorine and hydrogen fluoride at room temperature. The sensitivity to fluorine is 28.0±0.5mV\\/lg(p(F2)), the sensitivity to HF is 44.4±1.6mV\\/(p(HF)), and the detection is about 10ppb

W. Moritz; L. Bartholomaus; U. Roth; V. Filippov; A. Vasiliev; A. Terentjev

1999-01-01

144

Time resolved studies on pulsed fluorocarbon plasmas using chirped quantum cascade lasers  

NASA Astrophysics Data System (ADS)

The kinetics of stable species has been studied in situ in pulsed CF4/H2 radio frequency discharges by means of time resolved quantum cascade laser absorption spectroscopy. The absorption spectra were usually recorded with a time resolution of 5 ms and required a multi-species analysis, because of interfering complex absorption features of CF4 and C3F8. For this reason, measurements were carried out at two different spectral positions. High resolution spectroscopic data were established by calibrating effective absorption cross sections and their relative temperature dependences for the relevant low pressure conditions (10 Pa). During the discharge a decrease in the CF4 density by ~12% was observed. The off-phase was characterized mainly by the gas exchange. The C3F8 density in the off-phase was found to be of the order of the detection limit (3 × 1013 cm-3). Spectra acquired during the plasma-on phase showed a rapid temperature-induced increase in the absorption signal and, additionally, suggested the influence of a short-lived broadband absorbing species. The reasonable assumption of the presence of CF4 hotbands has not yet enabled a further quantification.

Welzel, S.; Stepanov, S.; Meichsner, J.; Röpcke, J.

2010-03-01

145

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

NASA Astrophysics Data System (ADS)

Ion energy distribution (IED) measurements are reported for ions in the plasma molecular beam source of the imaging of radicals interacting with surfaces (IRIS) apparatus. The IEDs and relative intensities of nascent ions in C3F8 and C4F8 plasma molecular beams were measured using a Hiden PSM003 mass spectrometer mounted on the IRIS main chamber. The IEDs are complex and multimodal, with mean ion energies ranging from 29to92eV. Integrated IEDs provided relative ion intensities as a function of applied rf power and source pressure. Generally, higher applied rf powers and lower source pressures resulted in increased ion intensities and mean ion energies. Most significantly, a comparison to CF2 surface interaction measurements previously made in our laboratories reveals that mean ion energies are directly and linearly correlated to CF2 surface production in these systems.

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

2006-07-01

146

In situ analysis of aqueous structure and adsorption at fluorocarbon, hydrocarbon and mineral surfaces  

Microsoft Academic Search

Altering and controlling the properties of solid surfaces in aqueous or other liquid phase environments has been a sought after objective for decades. With the discovery of chemisorbed self-assembled monolayers, this dream has become a reality. Oxide and metal surfaces can now be readily coated with an array of commercially available products to produce a desired fnctionality. The presence of

Adam Justin Hopkins

2010-01-01

147

A technique for temperature mapping in fluorocarbon plasmas using planar laser-induced fluorescence of CF  

Microsoft Academic Search

Planar laser-induced fluorescence measurements of CF A 2?+–X 2&Pgr;(1,0) were used to determine two-dimensional maps of rotational temperature in CF4 plasmas. Measured rotational temperatures are expected to be in equilibrium with the gas temperature due to the long chemical lifetime of CF relative to the collision rate. Experiments were performed in the capacitively coupled Gaseous Electronics Conference rf reference cell

Kristen L. Steffens; Mark A. Sobolewski

2004-01-01

148

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

149

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

EPA Science Inventory

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

150

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

151

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

152

Release of Fluorocarbons from Insulation Foam in Home Appliances during Shredding  

Microsoft Academic Search

It is a current practice that refrigerators and freezers in many countries are shredded after the end of useful lives. The shredder residue is deposited in landfills. During the shredding process a significant fraction of blowing agent (BA) in the insulation foam may be released into the atmosphere. The objective of this study is to determine the fraction of BA

Charlotte Scheutz; Anders M. Fredenslund; Peter Kjeldsen; Michael Tant

2007-01-01

153

Proceedings of the 1993 Non-Fluorocarbon Insulation, Refrigeration and Air Conditioning Technology Workshop  

NASA Astrophysics Data System (ADS)

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

154

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

Microsoft Academic Search

The ATLAS silicon tracker community foresees an upgrade from the present octafluoropropane (C3F8) evaporative cooling fluid — to a composite fluid with a probable 10–20% admixture of hexafluoroethane (C2F6). Such a fluid will allow a lower evaporation temperature and will afford the tracker silicon substrates a better safety margin against leakage current-induced thermal runaway caused by cumulative radiation damage as

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

2011-01-01

155

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

Code of Federal Regulations, 2010 CFR

...pump and open the valve on the system. Take the sample as a liquid by chilling...collected, close the valve(s) and disconnect...that are either a liquid or a gas at room...hydrochloric acid and/or metal chlorides....

2010-07-01

156

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

157

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

Code of Federal Regulations, 2014 CFR

...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

158

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

Code of Federal Regulations, 2013 CFR

...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.”...

2013-07-01

159

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

Code of Federal Regulations, 2011 CFR

...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.”...

2011-07-01

160

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

Code of Federal Regulations, 2012 CFR

...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.”...

2012-07-01

161

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

162

Predictions of capillary oxygen transport in the presence of fluorocarbon additives  

E-print Network

to the endothelium. The model was applied to working hamster retractor muscle at normal and lowered hematocrit of 1.7 at a hematocrit of 43%. An additional increase of 6% was pre- dicted when the solubility increase was concentrated in the layer adjacent to the endothelium.At a hematocrit of 25

Eggleton, Charles

163

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

Microsoft Academic Search

Chlorofluorocarbons (CFCs) are on their way out, due to their role in stratospheric ozone depletion and the related international Montreal Protocol agreement and various national phaseout timetables. As the research, engineering development, and manufacturing investment decisions have ensued to prepare for this transition away from CFCs, the climate change issue has emerged and there has recently been increased attention on

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

1992-01-01

164

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

Microsoft Academic Search

Chlorofluorocarbons (CFCs) are on their way out, due to their role in stratospheric ozone depletion and the related international Montreal Protocol agreement and various national phaseout timetables. As the research, engineering development, and manufacturing investment decisions have ensued to prepare for this transition away from CFCs, the climate change issue has emerged and there has recently been increased attention on

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

1992-01-01

165

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

SciTech Connect

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

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

2000-01-15

166

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

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

167

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

NASA Astrophysics Data System (ADS)

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

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

1987-06-01

168

Mechanisms for CF2 radical generation and loss on surfaces in fluorocarbon plasmas  

E-print Network

that surfaces in radio frequency rf capacitively coupled discharges can be either sources or sinks of CF2 rates of etching and selectivity.1,2 Investigating surface reactions in these plasmas continues radio frequency rf plasma reactor indicating that the surface acts as a sink.9 This discrepancy can

Kushner, Mark

169

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

170

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

SciTech Connect

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

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

2013-11-14

171

Release of fluorocarbons from insulation foam in home appliances during shredding.  

PubMed

It is a current practice that refrigerators and freezers in many countries are shredded after the end of useful lives. The shredder residue is deposited in landfills. During the shredding process a significant fraction of blowing agent (BA) in the insulation foam may be released into the atmosphere. The objective of this study is to determine the fraction of BA released from foam during shredding, by comparing the BA content in insulation foam of refrigerator units before shredding with the BA content of shredded foam. All foam samples analyzed were manufactured with trichlorofluoromethane [CFC-11 (CCl3F)] as BA. The average content of BA in the insulation foam from eight U.S. refrigerator units manufactured before 1993 was found to be 14.9% +/- 3.3% w/w. Several refrigerator units also identified as being manufactured before 1993 were stockpiled and shredded at three shredder facilities, of which one was operated in both wet and dry modes. The selected shredder facilities represent typical American facilities for shredding automobiles, refrigerators, freezers, and other iron containing waste products. Shredded material was collected and separated on location into four particle size categories: more than 32 mm, 16-32 mm, 8-16 mm, and 0-8 mm. Adjusting for sample purity, it was found that the majority (>81%) of the foam mass was shredded into particles larger than 16 mm. The smallest size fraction of foam (0-8 mm) was found to contain significantly less BA than the larger size categories, showing that up to 68% +/- 4% of the BA is released from these fine particles during the shredding process. Because only a minor fraction of the foam is shredded into particles smaller than 8 mm, this has a minor impact on the end result when calculating the total BA release from the shredding process. Comparing BA content in shredded samples from the three shredder facilities with the measured average BA content of the eight refrigerator units, it was found that on average 24.2% +/- 7.5% of the initial BA content is released during the shredding process. PMID:18200930

Scheutz, Charlotte; Fredenslund, Anders M; Kjeldsen, Peter; Tant, Michael

2007-12-01

172

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

SciTech Connect

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

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

1995-04-24

173

Mechanism for the selective etch of silicon dioxide in a high-density, low-pressure, inductively coupled fluorocarbon plasma  

Microsoft Academic Search

A novel, end launched, m=0 mode helicon wave was developed through the application of an axial magnetic field to a flat, spiral coil, inductively coupled plasma source. The rf magnetic field structure in the plasma was determined with induction probes and shown to match the theory of an m=0 helicon wave. Helicon wave power deposition, determined from axial damping of

Mark Justin Sowa

1999-01-01

174

A Combined On-Line Acoustic Flowmeter and Fluorocarbon Coolant Mixture Analyzer for The ATLAS Silicon Tracker  

E-print Network

An upgrade to the ATLAS silicon tracker cooling control system may require a change from C3F8 (octafluoro-propane) to a blend containing 10-30% of C2F6 (hexafluoro-ethane) to reduce the evaporation temperature and better protect the silicon from cumulative radiation damage with increasing LHC luminosity. Central to this upgrade is a new acoustic instrument for the real-time measurement of the C3F8/C2F6 mixture ratio and flow. The instrument and its Supervisory, Control and Data Acquisition (SCADA) software are described in this paper. The instrument has demonstrated a resolution of 3.10-3 for C3F8/C2F6 mixtures with ~20%C2F6, and flow resolution of 2% of full scale for mass flows up to 30gs-1. In mixtures of widely-differing molecular weight (mw), higher mixture precision is possible: a sensitivity of C3F8 into the ATLAS pixel detector nitrogen envelope (mw difference 160) has been seen. The instrument has many potential applications, including the analysis of mixtures of hydrocarbons,...

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

2011-01-01

175

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

176

Elastohydrodynamic film thickness measurements with advanced ester, fluorocarbon, and polyphenyl ether lubricants to 589 K (600 F)  

NASA Technical Reports Server (NTRS)

Elastohydrodynamic (EHD) film thicknesses have been measured, by means of an X-ray technique, under conditions that closely simulate the ball-race contact in advanced turbine engine thrust bearings. The experiments were conducted with a rolling-disk machine using disks which yield a contact zone similar to that in the actual bearing. Both the rolling and spinning motions of the ball relative to the race were simulated by the apparatus. Four lubricants were evaluated at temperatures to 600 F and maximum Hertz stresses to 350,000 psi. The X-ray film thickness data correlated well with observations of surface distress (or lack thereof) in full-scale bearing tests with the same lubricants under similar conditions of temperature and load. The predicted variation of film thickness with speed and viscosity as verified, although the magnitude of measured film thickness was generally one-half to one-third of predicted values. An effect of stress greater than predicted was consistently observed in the higher stress range.

Parker, R. J.; Kannel, J. W.

1971-01-01

177

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

178

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

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

179

Surface patterning using plasma-deposited fluorocarbon thin films for single-cell positioning and neural circuit arrangement.  

PubMed

Micropatterning glass substrates with a plasma-deposited fluoropolymer thin film was shown to be an efficient approach to manipulate cell positioning. The glass windows promoted cell adhesion, whereas the surrounding fluoropolymer displays a cell-repelling character. Herein, multiple micropatterned substrates were developed with pattern dimensions sufficient to host solely single-cells. These single-cell arrays would allow analysis of individual cell response to stimulation without interference from cell-cell interactions. Mouse myoblast C2C12 cells and cortical neurons from mice were examined, both for amenability to patterning, as well as success of cell adhesion and cell morphology. Both cell types were found to have optimal adherence and growth on the glass surface, while cell adhesion and function was inhibited on the fluoropolymer. The C2C12 cells conformed to the shape of the pattern, while maintaining a healthy structure. Moreover, the neuron cells followed the hexagonal grid patterns and formed circuits, wherein the complexity of the connections depended on incubation time. PMID:21074849

Leclair, Amanda M; Ferguson, Stephen S G; Lagugné-Labarthet, François

2011-02-01

180

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

SciTech Connect

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

Clink, G.L.

1986-02-01

181

A Combine On-Line Acoustic Flowmeter and Fluorocarbon Coolant Mixture Analyzer for The ATLAS Silicon Tracker  

E-print Network

An upgrade to the ATLAS silicon tracker cooling control system may require a change from C3F8 (octafluoro-propane) to a blend containing 10-30% of C2F6 (hexafluoro-ethane) to reduce the evaporation temperature and better protect the silicon from cumulative radiation damage with increasing LHC luminosity. Central to this upgrade is a new acoustic instrument for the real-time measurement of the C3F8/C2F6 mixture ratio and flow. The instrument and its Supervisory, Control and Data Acquisition (SCADA) software are described in this paper. The instrument has demonstrated a resolution of 3.10-3 for C3F8/C2F6 mixtures with ~20%C2F6, and flow resolution of 2% of full scale for mass flows up to 30gs-1. In mixtures of widely-differing molecular weight (mw), higher mixture precision is possible: a sensitivity of < 5.10-4 to leaks of C3F8 into the ATLAS pixel detector nitrogen envelope (mw difference 160) has been seen. The instrument has many potential applications, including the analysis of mixtures of hydrocarbons, vapours for semi-conductor manufacture and anaesthesia.

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

2012-01-12

182

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

183

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

Microsoft Academic Search

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

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

1999-01-01

184

ESCA study of several fluorocarbon polymers exposed to atomic oxygen in low earth orbit or within or downstream from a radio-frequency oxygen plasma  

NASA Technical Reports Server (NTRS)

The ESCA (electron spectroscopy for chemical analysis) spectra of films of Tedlar, tetrafluoroethylene-hexafluoropropylene copolymer (in the form of a Teflon FEP coating on Kapton H, i.e., Kapton F), and polytetrafluoroethylene (Teflon or Teflon TFE), exposed to atomic oxygen O(3P) either in LEO on the STS-8 Space Shuttle or within or downstream from a radio-frequency oxygen plasma, were compared. The major difference in surface chemistry of Tedlar induced by the various exposures to O(3P) was a much larger uptake of oxygen when etched either in or out of the glow of an O2 plasma than when etched in LEO. In contrast, Kapton F exhibited very little surface oxidation during any of the three different exposures to O(3P), while Teflon was scarcely oxidized.

Golub, Morton A.; Wydeven, Theodore; Cormia, Robert D.

1989-01-01

185

Investigation of fluorocarbon plasma deposition from c-C{sub 4}F{sub 8} for use as passivation during deep silicon etching  

SciTech Connect

The passivation step used in the 'Bosch' process (alternating etching and deposition steps) to perform deep anisotropic silicon etching has been examined in detail. The effect of pressure, inductively coupled plasma power, temperature, flow rate, and bias power on both deposition rate and film composition has been explored over a relatively wide range. Deposition rate was found to vary significantly as a function of temperature, power, and pressure. In contrast, only two film composition regimes were observed: high fluorine-to-carbon ratio (F:C) films ({approx}1.6) at low pressure/high power versus low F:C films ({approx}1.2) at high pressure/low power. Optical emission spectroscopy of the deposition plasmas also show only two regimes: C{sub 2}, C{sub 3}, and F emission dominated (high F:C films) and CF{sub 2} emission dominated (low F:C films). A two-step deposition mechanism is assumed: carbon deposition followed by fluorination. Low F concentration and deposition from large fluorine-deficient C{sub x}F{sub y} species in the CF{sub 2}-rich plasmas result in the low F:C ratio films. Films deposited during an actual Bosch cycle generally mirror these bulk films, with slight differences. Analysis of etch:deposition rate ratios as a function of film F:C ratio indicates that, for the conditions studied here, a F:C ratio of 1.45 is optimal for Bosch processing (i.e., has the lowest etch:deposition rate ratio). Further analysis is needed to determine the effect of passivant F:C ratio on feature profiles.

Labelle, Catherine B.; Donnelly, Vincent M.; Bogart, Gregory R.; Opila, Robert L.; Kornblit, Avi [Lucent Technologies Bell Laboratories, 600 Mountain Ave., Murray Hill, New Jersey 07974 (United States)

2004-11-01

186

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

187

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

SciTech Connect

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

Xiang, H.; Komvopoulos, K. [Department of Mechanical Engineering, University of California, Berkeley, California 94720 (United States)] [Department of Mechanical Engineering, University of California, Berkeley, California 94720 (United States)

2013-06-14

188

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

189

High density fluorocarbon plasma etching of methylsilsesquioxane SiOC(H) low-k material and SiC(H) etch stop layer: surface analyses and investigation of etch mechanisms  

Microsoft Academic Search

This paper focuses on plasma etching and XPS surface analyses of new dielectric materials used in integrated circuits. We investigate by XPS surface modifications of methylsilsesquioxane low-k polymer (SiOC(H)) and amorphous hydrogenated silicon carbide (SiC(H)) when exposed to Ar, SF6 and C2F6-based high density plasmas. Ar and SF6 plasmas remove the carbonaceous groups from the surface leading to the formation

D. Eon; V. Raballand; G. Cartry; C. Cardinaud

2007-01-01

190

Etching of porous and solid SiO2 in Ar/c-C4F8, O2/c-C4F8 and Ar/O2/c-C4F8 plasmas  

E-print Network

be obtained between different materials such as SiO2, Si, and Si3N4.5,6 The choice of fluorocarbon plasmas for such applications.4,7,8 Etch mechanisms for Si, SiO2, and Si3N4 in fluorocarbon plasmas are similar and proceed the etch rates. The consumption of the fluorocarbon polymer by the oxygen in SiO2 and the nitrogen in Si3N4

Kushner, Mark

191

Implications of a Carbon Based Energy Tax for U.S. Agriculture Uwe A. Schneider*  

E-print Network

, nitrous oxide, hydro-fluorocarbons, perfluorocarbons, and sulphur hexafluoride by various percentage percent over the next decade. Carbon sequestration and renewable fuel incentives are specifically

McCarl, Bruce A.

192

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

Code of Federal Regulations, 2011 CFR

...Fibers *Fluorocarbon (Teflon) Fibers *Modacrylic Fibers *Nylon 6 Fibers Nylon 6 Monofilament *Nylon 66 Fibers Nylon 66 Monofilament *Polyamide Fibers (Quiana) *Polyaramid (Kevlar) Resin-Fibers *Polyaramid...

2011-07-01

193

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

Code of Federal Regulations, 2014 CFR

...Fibers *Fluorocarbon (Teflon) Fibers *Modacrylic Fibers *Nylon 6 Fibers Nylon 6 Monofilament *Nylon 66 Fibers Nylon 66 Monofilament *Polyamide Fibers (Quiana) *Polyaramid (Kevlar) Resin-Fibers *Polyaramid...

2014-07-01

194

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

Code of Federal Regulations, 2010 CFR

...Fibers *Fluorocarbon (Teflon) Fibers *Modacrylic Fibers *Nylon 6 Fibers Nylon 6 Monofilament *Nylon 66 Fibers Nylon 66 Monofilament *Polyamide Fibers (Quiana) *Polyaramid (Kevlar) Resin-Fibers *Polyaramid...

2010-07-01

195

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

Code of Federal Regulations, 2013 CFR

...Fibers *Fluorocarbon (Teflon) Fibers *Modacrylic Fibers *Nylon 6 Fibers Nylon 6 Monofilament *Nylon 66 Fibers Nylon 66 Monofilament *Polyamide Fibers (Quiana) *Polyaramid (Kevlar) Resin-Fibers *Polyaramid...

2013-07-01

196

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

Code of Federal Regulations, 2012 CFR

...Fibers *Fluorocarbon (Teflon) Fibers *Modacrylic Fibers *Nylon 6 Fibers Nylon 6 Monofilament *Nylon 66 Fibers Nylon 66 Monofilament *Polyamide Fibers (Quiana) *Polyaramid (Kevlar) Resin-Fibers *Polyaramid...

2012-07-01

197

Development of a special purpose spacecraft coating, phase 4  

NASA Technical Reports Server (NTRS)

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

Gillman, H. D.

1980-01-01

198

High performance rolling element bearing  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

199

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

200

Survival of Mammals Breathing Organic Liquids Equilibrated with Oxygen at Atmospheric Pressure  

Microsoft Academic Search

Because oxygen and carbon dioxide are very soluble in certain silicone oils and fluorocarbon liquids, these liquids will support respiration of mammals. Mice and cats respiring silicone oil die shortly after return to air breathing, while those breathing fluorocarbon survive for weeks. The respiration of mice is optimally supported by these organic liquids at about 20 degrees C. In cats,

Leland C. Clark Jr.; Frank Gollan

1966-01-01

201

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

Microsoft Academic Search

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

Douglas M. Robinson; Eckhard A. Groll

1998-01-01

202

Reciprocating down-hole sand pump  

SciTech Connect

This patent describes the invention of a continuously-operated reciprocating down-hole sand pump comprising: a steel polished plunger pipe that strokes back and forth within a steel honed pump barrel, and is equipped with a self-lubricating fluorocarbon V-ring system that is pressure-actuated during compression strokes; the self-lubricating fluorocarbon V-ring system also is self-actuated by means of coil springs to provide wiping action to the polished plunger pipe during suction strokes; the self-lubricating fluorocarbons V-ring system also self-adjusts by means of coil springs located adjacent the fluorocarbon V-ring so as to automatically compensate for V-ring wear; and the self-lubricating fluorocarbon V-ring system also is designed in such a manner so as to eliminate voids and discourage the extrusion of V-rings in high temperature and high-pressure applications.

Ruhle, J.L.

1987-04-28

203

Texturing polymer surfaces by transfer casting. [cardiovascular prosthesis  

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

204

Amorphous microcellular polytetrafluoroethylene foam film  

NASA Astrophysics Data System (ADS)

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

Tang, Chongzheng

1991-11-01

205

Comprehensive bioimaging with fluorinated nanoparticles using breathable liquids  

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

206

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...

207

HYDRAULIC STUDIES AND CLEANING EVALUATIONS OF ULTRAVIOLET DISINFECTION UNITS  

EPA Science Inventory

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

208

614 IEEE TRANSACTIONS ON DEVICE AND MATERIALS RELIABILITY, VOL. 4, NO. 4, DECEMBER 2004 Spray Cooling Using Multiple Nozzles: Visualization  

E-print Network

-temperature boiling point dielectric liquid compatible with electronics (e.g., fluorocarbons) is an attractive option transfer rates much higher than can be attained in pool boiling (typical CHF for pool boiling of FC-72 is W

Kim, Jungho

209

40 CFR Appendix B to Subpart B of... - Standard for Recover Equipment  

Code of Federal Regulations, 2011 CFR

...VA 22209. ARI 700-93—Specifications for Fluorocarbon Refrigerants 2.1.3CGA Publications—Available from CGA, Crystal Gateway #1, Suite 501, 1235 Jefferson Davis Highway, Arlington, VA 22202. CGA S-1.1—Pressure Relief Device...

2011-07-01

210

Earth's Endangered Ozone  

ERIC Educational Resources Information Center

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

Panofsky, Hans A.

1978-01-01

211

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

212

Search for plutonium-244 tracks in mountain pass bastnaesite  

USGS Publications Warehouse

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

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

1972-01-01

213

Atmospheric trace gas measurements with a new clean air sampling system  

SciTech Connect

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

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

1981-10-01

214

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

215

Preparation of stable colloidal dispersions in fluorinated liquids  

NASA Technical Reports Server (NTRS)

Chemical method for separating oil from water by liquid barrier which can be positioned magnetically is described. Fluorocarbon liquids containing colloidal suspension of magnetite is proposed. Chemical composition of magnetite and fluorinated ether polymer are presented.

Kaiser, R.

1972-01-01

216

Time resolved Langmuir probe measurements in inductively coupled plasmas  

Microsoft Academic Search

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

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

2002-01-01

217

Plasma-etching technology with in situ etched-surface modification for highly reliable low-k\\/Cu dual damascene interconnects  

Microsoft Academic Search

The plasma-etching technology presented in this paper is for fabricating highly reliable Cu dual damascene interconnects (DDI) with organic low-k film through modification of the in situ etched surface during low-k etching. Nitrogen-based plasma with oxygen and high-molecular-weight fluorocarbon gas (C>2) chemically modifies the sidewall surface of the etched low-k film, changing it into the carbon nitride with fluorocarbon-polymer passivation

Hiroto Ohtake; Shinobu Saito; Munehiro Tada; Takahiro Onodera; Yoshihiro Hayashi

2005-01-01

218

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

NASA Technical Reports Server (NTRS)

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

Ross, B.; Parker, J.

1982-01-01

219

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

NASA Astrophysics Data System (ADS)

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

Ross, B.; Parker, J.

1982-07-01

220

Macromolecule formation in low density CF4 plasmas: The influence of H2  

NASA Astrophysics Data System (ADS)

High molecular weight fluorocarbon species are regarded as important contributors to the nucleation of films and particulates in fluorocarbon plasmas. The chemical reaction mechanisms by which fluorocarbon macromolecules form within a plasma are generally unknown. To elucidate these mechanisms, experiments were conducted in a rf capacitively coupled discharge in a Gaseous Electronics Conference reference cell. The relationships between macromolecule growth and plasma pressure, power, flow rate, and the fraction of H2 in the CF4 gas feed are identified. Macromolecule growth was found to increase with increased pressure and rf power, and decreased flow rate. A set of electron-induced dissociation and radical-recombination reactions are simulated using Chemkin-Aurora, a commercially available plasma chemistry model, and are in good agreement with the experimental results of macromolecule growth. We show that a primary mechanism by which fluorocarbon macromolecules form in a plasma occurs by electron-induced dissociation of a fluoroalkane to produce a fluoroalkyl radical and a fluorine atom, followed by a three-body radical-radical recombination reaction with CF3. Hydrogen is shown to have a profound effect on this reaction sequence by reducing the gas phase atomic fluorine concentration through the formation of HF which in turn increases the CF3 concentration available to participate in the macromolecule growth process. At moderate levels of hydrogen in the feed gas (<20%), macromolecule growth is directly correlated with the fraction of hydrogen in the feed gas. At high concentrations of hydrogen, hydrofluorocarbon and hydrocarbon growth occurs in the plasma at the expense of fluorocarbon macromolecule growth. The conditions under which the formation of these species occurs is consistent with observations in the literature of dramatic reductions in silicon dioxide etching rate. The transition between the formation of fluorocarbon macromolecules and hydrocarbon species in a CF4/H2 plasma is shown to be fundamental to understanding the growth process of each class of species within the plasma.

Schabel, M. J.; Peterson, T. W.; Muscat, A. J.

2003-02-01

221

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

222

Vacuum ultraviolet radiation/atomic oxygen synergism in materials reactivity  

SciTech Connect

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. 8 refs.

Koontz, S.; Leger, L.; Albyn, K.; Cross, J. (NASA, Johnson Space Center, Houston, TX (USA) Los Alamos National Laboratory, NM (USA))

1990-06-01

223

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

224

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

225

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

SciTech Connect

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

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

2000-02-02

226

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

227

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

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

228

46 CFR 77.30-10 - Stowage.  

Code of Federal Regulations, 2012 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...

2012-10-01

229

46 CFR 77.30-10 - Stowage.  

Code of Federal Regulations, 2013 CFR

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

2013-10-01

230

46 CFR 77.30-10 - Stowage.  

Code of Federal Regulations, 2011 CFR

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

2011-10-01

231

46 CFR 77.30-10 - Stowage.  

Code of Federal Regulations, 2014 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...

2014-10-01

232

Noninvasive picosecond ultrasonic detection of ultrathin interfacial layers: CFx at the AVSi interface  

E-print Network

Noninvasive picosecond ultrasonic detection of ultrathin interfacial layers: CFx at the AVSi ultrasonics technique has been used to detect interfacial fluorocarbon (CF,) layers as thin as 0.5 nm between techniqueld based on pulsed picosecond ultrasonics which is sensitive to ultrathin interfacial layers

Rubloff, Gary W.

233

Cardiovascular disease and environmental exposure.  

PubMed Central

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

Rosenman, K D

1979-01-01

234

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 94, NO. D7, PAGES 9862-9872, JULY 20, 1989 Comparison of Model Results Transporting the Odd Nitrogen Family  

E-print Network

of Model Results Transporting the Odd Nitrogen Family With Results Transporting Separate Odd Nitrogen.These assumptionsare tested by comparing results for the family transportmodel(FTM), in which odd nitrogen(NOv = N for increased fluorocarbons, methane, and nitrous oxide. Although there are differences in odd nitrogen species

Jackman, Charles H.

235

Novel post-etching treatment of small windows in oxide for selective epitaxial growth  

Microsoft Academic Search

A novel post-etching treatment of small windows in oxide for selective epitaxial Si growth is presented. The treatment is a short reactive ion etch in a Cl2 plasma, applied after window etching. Transmission electron microscopy (TEM) analysis of grown structures shows that high quality epitaxy is obtained in windows as small as 46 nm, indicating effective removal of fluorocarbon contamination.

J. W. H. Maes; J. Caro; C. C. G. Visser; T. Zijlstra; E. W. J. M. van der Drift; S. Radelaar; F. D. Tichelaar; E. J. M. Fakkeldij

1997-01-01

236

Transparent fluids for 157-nm immersion lithography  

Microsoft Academic Search

More than 50 fluorocarbon liquids are measured for transpar- ency over the wavelength range 150 to 200 nm for the purpose of iden- tifying a suitably transparent fluid for use in 157-nm liquid immersion lithography. Purification methods such as degasification, distillation, silica gel drying, and supercritical fluid fractionation are investigated to determine the impact of residual contaminants on absorbance. The

Roderick R. Kunz; Michael Switkes; Roger F. Sinta; Jane E. Curtin; Roger H. French; Robert C. Wheland; Chien-Ping Chai Kao; Michael P. Mawn; Lois Lin; Paula M. Wetmore; Val J. Krukonis; Kara Williams

2004-01-01

237

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

NASA Astrophysics Data System (ADS)

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

Ross, B.

1981-09-01

238

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

239

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

240

Physiological measurements during radio-frequency irradiation.  

PubMed

Conventional techniques for monitoring physiological parameters are not suitable for use during RFR exposure. This research note describes transduction methods involving the use of fluorocarbon leads and a pneumatic pressure transducer for reliable measurement of the ECG and respiratory rate in anesthetized or restrained rats during radiofrequency irradiation. PMID:3193340

Frei, M; Jauchem, J; Heinmets, F

1988-01-01

241

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

242

Temperature Mapping in CF4 Plasmas using Planar Laser-Induced Fluorescence  

Microsoft Academic Search

Fluorocarbon plasmas are commonly used for dielectric etching. As model-based reactor design and process development become more prevalent, more data is needed for model validation. Spatial variations in translational temperatures can lead to spatial variations in gas density and reaction rates. Mapping of these temperature variations would provide useful information for modelers. In this work, 2-D temperature maps in CF4

Kristen L. Steffens; Mark A. Sobolewski

2002-01-01

243

Toxicity and bioaccumulation of hexachlorocyclopentadiene, hexachloronorbornadiene and heptachloronorbornene in larval and early juvenile fathead minnows, Pimephales promelas  

Microsoft Academic Search

Hexachlorocyclopentadiene is the key intermediate in the synthesis of stable chlorinated cyclodiene insecticides including aldrin, dieldrin, endrin, endosulfan, heptachlor, chlordane, isodrin and mirex (BROOKS 1974) o Some other products derived from hexachlorocyclopentadiene are nonflammable resins, fungicides, heat resistant and shock proof plastics, acids, esters, ketones and fluorocarbons. Using the Diels-Alder reaction, hexachlorocyclopentadiene can be transformed by the addition of vinyl

R. L. Spehar; G. D. Veith; D. L. DeFoe; B. V. Bergstedt

1979-01-01

244

Greenhouse effect of chlorofluorocarbons and other trace gases  

Microsoft Academic Search

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

James Hansen; Andrew Lacis; Michael Prather

1989-01-01

245

Thin FC film for sidewall passivation in SCREAM process for MEMS  

Microsoft Academic Search

SCREAM process for releasing micromechanical MEMS structures using plasma polymerized fluorocarbon thin film for trench sidewall passivation is reported. The developed process is designed as a one mask process, and all etchings and depositions are fabricated in the same etching system (standard capacitive coupled RIE), as one-step-one-run process.

D. Vrtacnik; D. Resnik; U. Aljancic; M. Mozek; S. Penic; S. Amon

2007-01-01

246

Silver inkjet printing with control of surface energy and substrate temperature  

Microsoft Academic Search

The characteristics of silver inkjet printing were intensively investigated with control of surface energy and substrate temperature. A fluorocarbon (FC) film was spincoated on a silicon (Si) substrate to obtain a hydrophobic surface, and an ultraviolet (UV)\\/ozone (O3) treatment was performed to control the surface wettability of the FC film surface. To characterize the surface changes, we performed measurements of

S.-H. Lee; K.-Y. Shin; J. Y. Hwang; K. T. Kang; H. S. Kang

2008-01-01

247

Plasma etching as a diagnostic technique in silicon surface studies  

Microsoft Academic Search

This paper describes a new application of plasma etching, namely as an aid to the characterization of specular semiconductor surfaces. The technique, which is simple and quick to perform, consists of subjecting the semiconductor slice to a brief etching treatment in a fluorocarbon plasma at low pressure, followed by inspection of the surface, using Nomarski microscopy. The whole operation is

D. P. Griffiths; S. H. Bradley

1977-01-01

248

Plasma etching as a diagnostic technique in silicon surface studies  

Microsoft Academic Search

A new application of plasma etching is described as an aid to the characterization of specular semiconductor surfaces. The technique, which is simple and quick to perform, consists of subjecting the semiconductor slice to a brief etching treatment in a fluorocarbon plasma at low pressure, followed by inspection of the surface, using Nomarski microscopy. The whole operation is designated diagnostic

D. P. Griffiths; S. H. Bradley

1977-01-01

249

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...

250

Activation of CF bonds using Cp*2ZrH2: a diversity of mechanisms  

E-print Network

Activation of C­F bonds using Cp*2ZrH2: a diversity of mechanisms William D. Jones Department at Dalton Discussion No. 6, 9­11th September 2003, University of York, UK. William D. Jones was born, kinetics, thermodynamics, and synthetic applications. William D. Jones chemistry of fluorocarbons

Jones, William D.

251

Temperature feedback in a stratospheric model  

Microsoft Academic Search

Perturbing the stratospheric composition affects the stratospheric temperature profile via the radiation balance. Changes in temperature affect chemical reaction rates, which in turn feed back on stratospheric composition. The effect of temperature feedback on ozone concentration has been investigated for three types of perturbations: (1) stratospheric injection of NO\\/sub x\\/, (2) release of fluorocarbons, and (3) doubling COâ. Temperature feedback

Frederick M. Luther; Donald J. Wuebbles; Julius S. Chang

1977-01-01

252

In situ diode laser absorption measurements of plasma species in a gaseous electronics conference reference cell reactor  

E-print Network

In situ diode laser absorption measurements of plasma species in a gaseous electronics conference-salt diode lasers are used to probe fluorocarbon-based plasmas used for etching of silicon and silicon dioxide in a gaseous electronics conference reference cell reactor. The diode laser sensor is used

253

Droplet manipulation on a hydrophobic textured surface with roughened patterns  

Microsoft Academic Search

A novel concept is proposed and verified, experimentally and theoretically, to manipulate droplets without external power sources. The proposed device is a hydrophobic surface containing specific roughness gradients, which is composed of several textured regions with gradually increased structural roughness. Hydrophobic materials of four types, photoresist AZ6112, Teflon, Parylene C, and plasma polymerization fluorocarbon film (PPFC)-are adopted to fabricate the

Jing-Tang Yang; Julia C. Chen; Ker-Jer Huang; J. Andrew Yeh

2006-01-01

254

Optically trapped aqueous droplets for single molecule studies J. E. Reiner, A. M. Crawford, R. B. Kishore, Lori S. Goldner, and K. Helmersona  

E-print Network

; published online 7 July 2006 We demonstrate a technique for creating, manipulating, and combining femtoliter­5 or adsorption6­9 of molecules on a surface or in porous materials.10,11 For such strategies, the role of surface approach to eliminate hydrophilic molecules from the hydrophobic fluorocarbon matrix; the molecules

Goldner, Lori S.

255

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...

256

Anode modification in organic light-emitting diodes by low-frequency plasma polymerization of CHF3  

NASA Astrophysics Data System (ADS)

Plasma polymerization of CHF3 at low frequencies was utilized for anode modification in organic light-emitting diodes. The polymerized fluorocarbon films have a high ionization potential and a relatively low resistivity. The devices with a polymer-coated anode of indium-tin-oxide exhibited enhanced hole injection and superior operational stability.

Hung, L. S.; Zheng, L. R.; Mason, M. G.

2001-01-01

257

Use of an organoleptic tracer (mercaptan) for testing for leaks in safety equipment.  

PubMed Central

A safe, rapid, sensitive, and economical method is presented for detecting leaks in gas-tight laboratory cabinets and other apparatus. This method, using no fluorocarbons and requiring no prior decontamination, is effective under negative, neutral, or positive chamber conditions. PMID:596879

Malligo, J E

1977-01-01

258

Electrical Control of Spatial Uniformity of Chamber-Cleaning Plasmas Investigated using Planar Laser-Induced Fluorescence  

Microsoft Academic Search

Fluorocarbon plasmas are widely used by the semiconductor industry for in situ cleaning of PECVD chambers. The spatial characteristics of these plasmas must be optimized to maximize the cleaning rate at appropriate surfaces. Previous studies in the GEC Reference Cell have indicated that the spatial distributions of chemically reactive species are correlated to the rf current at the upper, grounded

Kristen L. Steffens; Mark A. Sobolewski

1998-01-01

259

Improved Radiography Of Wooden Parts  

NASA Technical Reports Server (NTRS)

Technique developed to increase radiographic contrasts of inherent latent defects in wood. Involves introduction of radiopaque substance into defect site and subjecting site to penetrating radiation. Radiopaque penetrant used is commercially available fluorocarbon cleaning solvent, trichlorotrifluoroethane. Applicable in inspection of wooden aircraft components, fan and wind-turbine blades, marine parts, insulators, and other wooden components, assemblies, and structures.

Berry, Maggie L.; Berry, Robert F., Jr.

1990-01-01

260

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

261

Isolating fluorinated carbocations{ Christos Douvris, Evgenii S. Stoyanov, Fook S. Tham and Christopher A. Reed*  

E-print Network

Isolating fluorinated carbocations{ Christos Douvris, Evgenii S. Stoyanov, Fook S. Tham, fluorinated benzyl-type carbocations such as (p-FC6H4)2CF+ , (p-FC6H4)(CH3)CF+ and fluorinated trityl ions of fluorocarbons,2,3 make the characterization of fluorinated carbocations important. The potential value of X

Reed, Christopher A.

262

An Overview Fluorination Strategies  

E-print Network

An Overview of Fluorination Strategies Kiel Lazarski Porco Research Group Literature Presentation February 13th, 2014 #12;The Relevance of Fluorocarbons The carbon­fluorine bond is the strongest carbon­heteroatom bond · C­F ~125 kcal/mol; C­C ~88 kcal/mol . Fluorine is significantly more electronegative than carbon

Porco Jr., John A.

263

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

PubMed

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

Schvartzman, M; Wind, S J

2009-04-01

264

Method of making circulating electrolyte electrochemical cell having gas depolarized cathode with hydrophobic barrier layer  

Microsoft Academic Search

A method is described of making a gas depolarized cathode particularly adapted for use in a circulating electrolyte electrochemical cell comprising: (a) forming a carbonized fiber ribbed porous substrate; (b) press-molding a self-supporting layer of a fluorocarbon polymer that contains carbon particles; (c) applying a layer of an oxygen reducing catalyst on one side of the flurocarbon polymer layer; and

G. A. Gruver; H. R. Kunz

1987-01-01

265

Polyphosphazene Icephobic Coating Materials  

NASA Technical Reports Server (NTRS)

Coating materials consisting mostly of modified polyphosphazene (Class FZ) elastomers provide better protection against icing than fluorocarbon polymers and silicone elastomers. Reduces adhesive force between ice and surface. As consequence, increasing weight of ice, wind loading, or vibration of surface causes ice to be shed. New icephobic coats reduce accumulation of ice on aircraft, radomes, antennas, ships, and power-transmission lines.

Willis, Paul B.

1992-01-01

266

Polymer Communication The swelling behaviour of perfluorinated ionomer membranes in  

E-print Network

and bulk swelling of "Nafion " perfluorinated ionomer membranes in mixtures of ethanol and water alone. The conclusion is that the ethanol plasticises the fluorocarbon matrix in Nafion, allowing with water alone. 2000 Elsevier Science Ltd. All rights reserved. Keywords: Nafion; Small angle X

Elliott, James

267

Global warming and end-use efficiency implications of replacing CFCs  

Microsoft Academic Search

The direct contribution of CFCs to calculated global warming has been recognized for some time. As a result of the international agreement to phase out CFCs due to stratospheric ozone and the ensuing search for suitable alternatives, there has recently been increased attention on the DIRECT global warming potential (GWP) of the fluorocarbon alternatives as greenhouse gases. However, to date

P. D. Fairchild; S. K. Fischer

1991-01-01

268

Vesicle Formation of a 1:1 Catanionic Surfactant Mixture in Ethanol Solution  

E-print Network

Vesicle Formation of a 1:1 Catanionic Surfactant Mixture in Ethanol Solution J.-B. Huang,* B (1989-1992), similar work was done in our laboratory, using mixed surfactants of carboxylate have been reported, which concentrated on the systems of double-chained fluorocarbon surfactants.6

Huang, Jianbin

269

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

Code of Federal Regulations, 2013 CFR

...fiber-forming substance is a synthetic polymer composed of at least 50% by weight of a cross-linked melamine polymer. (x) Fluoropolymer. A manufactured fiber containing at least 95% of a long-chain polymer synthesized from aliphatic fluorocarbon...

2013-01-01

270

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

Code of Federal Regulations, 2012 CFR

...fiber-forming substance is a synthetic polymer composed of at least 50% by weight of a cross-linked melamine polymer. (x) Fluoropolymer. A manufactured fiber containing at least 95% of a long-chain polymer synthesized from aliphatic fluorocarbon...

2012-01-01

271

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

Code of Federal Regulations, 2014 CFR

...fiber-forming substance is a synthetic polymer composed of at least 50% by weight of a cross-linked melamine polymer. (x) Fluoropolymer. A manufactured fiber containing at least 95% of a long-chain polymer synthesized from aliphatic fluorocarbon...

2014-01-01

272

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

273

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

NASA Technical Reports Server (NTRS)

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

Ross, B.

1981-01-01

274

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

275

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

NASA Technical Reports Server (NTRS)

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

Pei, Xiong-Skiba

1999-01-01

276

Nanometer-Scale Water- and Proton-Diffusion Heterogeneities across Water Channels in Polymer Electrolyte Membranes.  

PubMed

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

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

2015-03-16

277

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

SciTech Connect

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

William Tuminello; Maciej Radosz; Youqing Shen

2008-11-01

278

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

SciTech Connect

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

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

2000-02-02

279

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

NASA Astrophysics Data System (ADS)

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

Sokolova, Anastasiya

280

The millimeter and submillimeter spectrum of CF 2 and its production in a dc glow discharge  

NASA Astrophysics Data System (ADS)

Extensive measurements of the free radical CF 2 were made with microwave techniques in the millimeter and submillimeter spectral region. For this work, CF 2 was observed in a glow discharge of fluorocarbons. Cell conditioning is shown to dramatically alter the concentration of CF 2. The rotational transition frequencies were analyzed in the context of Watson's reduced centrifugal distortion Hamiltonian. The results of this analysis include both precise rotation and distortion parameters and an accurate spectral map.

Charo, Arthur; De Lucia, Frank C.

1982-08-01

281

Thin film encapsulation technology for harms using sacrificial CF-polymer  

Microsoft Academic Search

This paper reports on a new method for thin film encapsulation of microelectromechanical systems (MEMS) using plasma enhanced chemical vapor deposited (PECVD) fluorocarbon polymer as sacrificial material and a stress optimized SiO\\/SiN\\/Al capping layer. Because of the oxygen plasma-based removal of the sacrificial organic layer, this technique is applicable for a wide range of MEMS technologies—from surface to high aspect

D. Reuter; A. Bertz; M. Nowack; T. Gessner

2008-01-01

282

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

Microsoft Academic Search

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

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

2012-01-01

283

Antisoiling Coatings for Solar-Energy Devices  

NASA Technical Reports Server (NTRS)

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

Cuddihy, E. F.; Willis, P.

1986-01-01

284

In-beam tests of a ring imaging Cherenkov detector with a multianode photomultiplier readout  

NASA Astrophysics Data System (ADS)

A ring-imaging Cherenkov counter read out by a 100-channel PMT of active area 10 × 10 cm 2 was operated successfully in a test beam at the BNL AGS with several radiator gases, including the heavy fluorocarbon C 4F 10. Ring radii were measured for electrons, muons, pions and kaons over the particle momentum range from 2 to 12 GeV/ c, and a best resolution of {? r}/{r} = 2.3% was obtained.

Debbe, R.; Gushue, S.; Moskowitz, B.; Norris, J.; Olness, J.; Videbæk, F.

1995-02-01

285

New Gas Chemistry for High-Performance SiO2 Patterning in Sub0.1 mu m ULSIs  

Microsoft Academic Search

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

Seiji Samukawa

2002-01-01

286

UV-resist, Water-repellent Breathable Fabric as Protective Textiles  

Microsoft Academic Search

The demand for healthy lifestyles and comfort drives researchers to explore newer techniques to impart more functional properties in textiles. An attempt has been made to produce UV-resist, breathable fabrics for use in the cold regions of India as high-altitude fabrics. For UV-resist property, a dispersion of benzotrizol-type derivative and a silicone-based product are taken and perfluoro-alkyl-type fluorocarbon-based compound and

P. De; M. D. Sankhe; S. S. Chaudhari; M. R. Mathur

2005-01-01

287

Phase III multicenter trial comparing the efficacy of 2% dodecafluoropentane emulsion (EchoGen) and sonicated 5% human albumin (Albunex) as ultrasound contrast agents in patients with suboptimal echocardiograms  

Microsoft Academic Search

Objectives. This study was performed to compare the safety and efficacy of intravenous 2% dodecafluoropentane (DDFP) emulsion (EchoGen) with that of active control (sonicated human albumin [Albunex]) for left ventricular (LV) cavity opacification in adult patients with a suboptimal echocardiogram.Background. The development of new fluorocarbon-based echocardiographic contrast agents such as DDFP has allowed opacification of the left ventricle after peripheral

Paul A Grayburn; James L Weiss; Terrence C Hack; Elizabeth Klodas; Joel S Raichlen; Manni A Vannan; Allan L Klein; Dalane W Kitzman; Steven G Chrysant; Jerald L Cohen; David Abrahamson; Elyse Foster; Julio E Perez; Gerard P Aurigemma; Julio A Panza; Michael H Picard; Benjamin F Byrd; Douglas S Segar; Stuart A Jacobson; David J Sahn; Anthony N DeMaria

1998-01-01

288

Mechanisms of etching and polymerization in radiofrequency discharges of CF4–H2, CF4–C2F4, C2F6–H2, C3F8–H2  

Microsoft Academic Search

Some results obtained during the etching of Si or the deposition of fluorocarbon films over Si substrates uncoupled from ground in rf plasmas fed with CF4–H2, C2F6–H2, C3F8–H2 and CF4–C2F4 mixtures are presented. The polymerization process is explained on the basis of a mechanism which involves CF and\\/or CF2 radicals as building blocks as well as an activation of the

R. d’Agostino; F. Cramarossa; V. Colaprico; R. d’Ettole

1983-01-01

289

Time resolved QCLAS measurements in pulsed cc-rf CF4\\/H2 plasmas  

Microsoft Academic Search

Fluorocarbon containing capacitively coupled radio frequency (cc-rf) plasmas are widely used in technical applications and as model systems for fundamental investigations of complex plasmas. Absorption spectroscopy based on pulsed quantum cascade lasers (QCL) was applied in the mid-IR spectral range of 1269-1275 cm-1. Absolute densities of the precursor molecule CF4 and of the stable product C3F8 were measured with a

S. Stepanov; S. Welzel; J. Röpcke; J. Meichsner

2009-01-01

290

General Chemistry Division. Quarterly report, October-December 1979  

SciTech Connect

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

Not Available

1980-02-15

291

Chemically induced coalescence in droplet-based microfluidics.  

PubMed

We present a new microfluidic method to coalesce pairs of surfactant-stabilized water-in-fluorocarbon oil droplets. We achieve this through the local addition of a poor solvent for the surfactant, perfluorobutanol, which induces cohesion between droplet interfaces causing them to merge. The efficiency of this technique is comparable to existing techniques providing an alternative method to coalesce pairs of droplets. PMID:25537080

Akartuna, Ilke; Aubrecht, Donald M; Kodger, Thomas E; Weitz, David A

2015-02-21

292

Fine Contact Hole Etching in Magneto-Microwave Plasma  

Microsoft Academic Search

Characteristics of fine contact hole etching have been investigated in hydro-fluorocarbon magneto-microwave plasma focusing on the z component of the gradient of magnetic field at 0.0875 T ( dB\\/ dz) and peak-to-peak voltage of RF bias (V pp) as parameters. Decrease of dB\\/ dz drastically decreases the etch rate of boro-phospho silicate glass (BPSG), critical dimension loss (defined as diameter

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

1994-01-01

293

Carbon/fluorine bond activation of perfluorinated arenes with Bradley M. Kraft, William D. Jones *  

E-print Network

as an active functional group is a significant chemical challenge. Some of the major goals in carbonÁ/fluorine bond activation studies include the functionalization of saturated fluorocarbons and the conversions) reacts with C6F6 in the presence of PEt3 or Ni(PEt3)4 to give trans-Ni(PEt3)2(C6F5)F [7]. [(dtbpm

Jones, William D.

294

Pyrolytically prepared carbon from fluorine–GIC  

Microsoft Academic Search

Formation mechanism, crystallinity, porosity and chemical reactivity were studied on the carbon prepared by pyrolysis of single phase, stage-1 fluorine–graphite intercalation compound (fluorine–GIC; CxF). The stage-1 C2.5F directly decomposes to fluorocarbon gases and carbon above 650 K, without forming higher stage compounds. The pyrocarbon prepared from C2.5F gives hkl diffraction peaks indicating graphite-like stacking order of graphene layers. This carbon

Yuta Sato; Soshi Shiraishi; Hirotaka Watano; Rika Hagiwara; Yasuhiko Ito

2003-01-01

295

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

296

International research into chlorofluorocarbon (CFC) alternatives  

SciTech Connect

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

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

1992-05-01

297

High Microvascular Endothelial Water Permeability in Mouse Lung Measured by a Pleural Surface Fluorescence Method  

Microsoft Academic Search

Transport of water between the capillary and airspace compartments in lung encounters serial barriers: the alveolar epithelium, interstitium, and capillary endothelium. We previously reported a pleural surface fluorescence method to measure net capillary-to-airspace water transport. To measure the osmotic water permeability across the microvascular endothelial barrier in intact lung, the airspace was filled with a water-immiscible fluorocarbon. The capillaries were

Ethan P. Carter; Bence P. Ölveczky; Michael A. Matthay; A. S. Verkman

1998-01-01

298

Stratospheric halogens from the western Pacific ocean  

Microsoft Academic Search

Natural, short-lived halocarbons play a role in the stratospheric ozone budget, besides the anthropogenic emitted long-lived chlorine- and bromine fluorocarbons. The tropical oceans are a known source of reactive iodine and bromine to the atmosphere in the form of iodinated and brominated methanes (VSLS), as methyl iodide (CH3I), dibromomethane (CH2Br2) and bromoform (CHBr3), which contributes to reactive bromine within the

B. Quack; K. Krueger; S. Tegtmeier; E. L. Atlas; A. Bracher; T. Dinter; S. Wache; D. Wallace

2010-01-01

299

Decongestion of high-resolution FTIR-spectra and assignment of CHF 2CF 3  

Microsoft Academic Search

We have developed an enclosive flow cell based on the design of Bauerecker in order to obtain rotationally and vibrationally cold spectra of species such as fluorocarbons and have recorded high-resolution FTIR-spectra of a number of species. In this paper we review the enclosive flow method for obtaining cooled spectra and compare for the molecules CH2FCF3 and c-C4F8 results with

Don McNaughton; Ivana Aleksic; Dominique R. T. Appadoo; Christopher D. Thompson; Evan G. Robertson

2004-01-01

300

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.

301

Wall relaxation rates for an optically pumped Na vapor  

NASA Astrophysics Data System (ADS)

The wall relaxation rates for an optically pumped Na vapor have been measured for a variety of wall surfaces. We find that fluorocarbon rubber (Fluorel or Viton) at a temperature of 250°C has a relaxation rate that corresponds on the average to 10-15 bounces before depolarization occurs. A surface with a relaxation rate this small is potentially very important for use in the polarized Na vapor charge exchange target used in the optically pumped polarized H - ion source.

Swenson, D. R.; Anderson, L. W.

1985-08-01

302

Effect of electron beam irradiation on the properties of crosslinked rubbers  

NASA Astrophysics Data System (ADS)

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

Banik, Indranil; Bhowmick, Anil K.

2000-05-01

303

Fluorination of silicone rubber by plasma polymerization  

NASA Astrophysics Data System (ADS)

Plasma polymerized fluorocarbon (PPFC) films were deposited onto various silicone rubber substrates, including O-rings, to decrease oil uptake. Depositions were performed using a radio frequency (rf)-powered plasma reactor and various fluorocarbon monomers, such as C2F6, C2F 5H, C3F6, and 1H,1H,2H-perfluoro-1-dodecene. PPFC films which were most promising for inhibiting oil uptake were deposited with 1H,1H,2H-perfluoro-1-dodecene, and were composed predominantly of perfluoromethylene (CF2) species. These films displayed low critical surface energies (as low as 2.7 mJ/m2), and high contact angles with oil (84°), which were correlated with the amount of CF2 species present in the film. For the films with the highest degree of CF2 (up to 67%), CF2 chains may have been oriented slightly perpendicular to the substrate and terminated by CF3 species. Adhesion of the PPFC films directly to silicone rubber was found to be poor. However, when a plasma polymerized hydrocarbon interlayer was deposited on the silicone rubber prior to the fluorocarbon films, adhesion was excellent. O-rings coated with multilayer fluorocarbon films showed 2.6% oil uptake after soaking in oil for 100 hrs at 100°C. Due to variability in data, and the low quality of the industrial grade silicone rubber, the oil uptake mechanism was determined to be from oil flowing through flaws in the film due to defects within the substrate, not from generalized diffusion through the film. This mechanism was confirmed using higher quality silicone rubber, which showed little or no oil diffusion. Therefore, this film may perform well as an oil-repelling barrier when deposited on a high quality silicone rubber.

Fielding, Jennifer Chase

304

Planar Laser-Induced Fluorescence Detection of Gas-Phase Intermediates in Plasmas  

Microsoft Academic Search

Low-pressure radio-frequency (rf) fluorocarbon plasmas are extensively used for etching and chamber-cleaning during microelectronics device fabrication. For efficient optimization of etch rate, spatial uniformity and reproducibility, an understanding of the plasma physics and chemistry is desired. Models which are necessary to understand the complex plasma processes require experimental input and must be rigorously verified by comparison to experimental measurements. Planar

Kristen L. Steffens

1997-01-01

305

Quantitatively controlled nanoliter liquid manipulation using hydrophobic valving and control of surface wettability  

Microsoft Academic Search

In this paper, we discuss nanoliter metering, transportation, merging, and biochemical reaction on a nanoliter fluidic chip. The proposed nanoliter fluidic handling is based on passive fluidic control using hydrophobic valving and liquid flow control by selective wettability patterning. For the selective patterning of the wettability, a hydrophobic fluorocarbon (FC) film (a mixture of FluoradTM from 3M, USA) was spin-coated

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

2003-01-01

306

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

SciTech Connect

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

Peterman, J.A.; Feld, W.A. [Wright State Univ., Dayton, OH (United States)

1995-12-31

307

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

308

Combined pressure and subcooling effects on pool boiling from a PPGA chip package  

Microsoft Academic Search

This study presents a detailed experimental investigation of the combined effects of pressure and subcooling on nucleate pool boiling and critical heat flux (CHF) for degassed fluorocarbon FC-72 boiling on a plastic-pin-grid-array (PPGA) chip package. In these experiments, pressure was varied between 101.3 and 303.9 kPa, and the subcooling ranged from 0 to 65°C. As expected, lower wall superheats resulted

A. A. Watwe; A. Bar-Cohen; A. McNeil

1996-01-01

309

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

NASA Technical Reports Server (NTRS)

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

Ross, B.; Parker, J.

1983-01-01

310

Novel fluorohydrocarbons  

NASA Technical Reports Server (NTRS)

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

Scherer, Kirby V. (Inventor)

1979-01-01

311

Plasma etching of SiO2 and Si_3N4 with NF_3\\/C_2H4 - a new approach to reduce global warming gas production  

Microsoft Academic Search

Plasma etching of SiO2 in the fabrication of semiconductor devices is normally achieved by using a fluorocarbon gas to produce: fluorine for chemical etching; a very thin steady-state intermediary film deposited on the surface being etched; and energetic ions. Unfortunately the byproducts of this process are strongly global warming gases. Here we report the first results of experiments designed to

P. Machima; N. Hershkowitz

2004-01-01

312

Silicon oxide and silicon nitride etch mechanisms in nitrogen trifluoride\\/ethylene plasma  

Microsoft Academic Search

Low-pressure inductive plasma was used to study SiO 2 and Si3N4 etching with the NF3\\/C 2H4-based gas chemistry. NF3 and C2H 4 were used so that fluorine and carbon could be supplied from parent gases other than strongly global warming fluorocarbons, which are conventionally used in industry. Experiments were performed at low pressure (<10 mTorr) and low flow rates to

Puthajat Machima

2005-01-01

313

SiO2 and Si3N4 etch mechanisms in NF3\\/hydrocarbon plasma  

Microsoft Academic Search

Low-pressure inductive plasma was used to study SiO2 and Si3N4 etching with NF3\\/hydrocarbon chemistry. NF3 and a hydrocarbon were used so that fluorine and carbon could be supplied from feed gases other than global warming fluorocarbons. Etch rates of SiO2 are less than the Si3N4 etch rates over a wide range of conditions. With 50 W of wafer power, the

Puthajat Machima; Noah Hershkowitz

2006-01-01

314

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

Microsoft Academic Search

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

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

2000-01-01

315

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

316

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

317

A low-background gamma-ray assay laboratory for activation analysis  

Microsoft Academic Search

The sources of background in a gamma-ray detector were experimentally determined in underground and surface counting rooms, and an optimized shield was constructed at NIST. The optimum thickness of lead was 10-15 cm, with a greater thickness giving an increased background due to the buildup of tertiary cosmic-ray particles. Neither cadmium, tin, copper nor plastic (hydrocarbon or fluorocarbon) was desirable

Richard M. Lindstrom; David J. Lindstrom; Lester A. Slaback; John K. Langland

1990-01-01

318

Cardiac arrhythmias during occupational exposure to fluorinated hydrocarbons.  

PubMed Central

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

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

1990-01-01

319

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

PubMed

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

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

2014-11-25

320

Proposal to produce novel, transparent radiation hard low refractive index polymers. Final report, 1 October-31 December 1993  

SciTech Connect

Low and high molecular weight polymers of heptafluorobutyl methacrylate, HFBM, were prepared for commercial evaluation by Bicron, an optical fiber manufacturer. Polymers were evaluated as low refractive index fiber cladding materials. Test results of Low MW polymer solutions gave excellent results. Higher MW polymers were prepared for cladding by melt co-extrusion. Corning Glass Corp, also expressed an interest in these cladding materials. These results appear to be sufficiently unique that a search has been initiated to determine patentability of the soluble fluorocarbon acrylate, methacrylate and copolymer compositions for cladding use. This research resulted in identifying a radiation hard, low refractive index polymer, poly(heptafluorobutyl methacrylate), P(HFBM) as the best candidate for a novel cladding material. P(HFBM) has a refractive index of 1.387. When used to clad a styrene core, the theoretical light propagation efficiency is 50% greater than that of styrene fiber core clad with PMMA, a common commercial cladding material. These polymers will be the only commercial fluorocarbon acrylic cladding polymers available to U.S. manufacturers. Japanese optical fiber manufacturers produce fluorocarbon clad fibers but their polymers are not available to U.S. manufacturers. These polymers can fill an urgent need in the optical fiber market.

Schuman, P.D.; Harmon, J.

1994-02-09

321

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

NASA Astrophysics Data System (ADS)

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

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

322

Mesoporous silica materials with an extremely high content of organic sulfonic groups and their comparable activities with that of concentrated sulfuric acid in catalytic esterification.  

PubMed

Mesoporous silica materials (HS-JLU-20) with an extremely high content of mercaptopropyl groups have been successfully synthesized using fluorocarbon-hydrocarbon surfactant mixtures through a simple co-condensation approach of tetraethyl orthosilicate (TEOS) and (3-mercaptopropyl)trimethoxysilane (MPTS), which are characterized by X-ray diffraction (XRD), nitrogen adsorption and desorption isotherms, transmission electron microscopy (TEM), CHNS elemental analysis, thermogravimetry analysis (TGA), and (29)Si NMR spectroscopy. The results show that HS-JLU-20 samples with molar ratios of MPTS/(MPTS + TEOS) at 0.5-0.8 in the starting synthetic gels still show their mesostructures, while HS-SBA-15 with the molar ratio of MPTS/(MPTS + TEOS) at 0.50 completely loses its mesostructure in the absence of fluorocarbon surfactant. Possibly, fluorocarbon surfactant containing N(+) species with a positive charge could effectively interact with negatively charged mercapto groups in the synthesis of HS-JLU-20 materials, resulting in the formation of mesoporous silicas with good cross-linking of silica condensation even at an extremely high content of organic mercapto groups. More interestingly, after the treatment with hydrogen peroxide, HSO(3)-JLU-20 materials with an extremely high content of organic sulfonic groups exhibit comparable activity with liquid concentrated sulfuric acid in catalytic esterification of cyclohexanol with acetic acid. PMID:16854112

Feng, Ye-Fei; Yang, Xiao-Yu; Di, Yan; Du, Yun-Chen; Zhang, Yong-Lai; Xiao, Feng-Shou

2006-07-27

323

Detection of Chamber Conditioning Through Optical Emission and Impedance Measurements  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

324

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

325

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

PubMed

In this study we present methods to physico-chemically modify micropatterned cell culture substrates that were manufactured using plasma lithography to incorporate affinity structures for specific cell binding. The surfaces consist of a pattern of a fluorocarbon plasma polymer with feature sizes between 5 and 100 microm on a background of a non-fouling tetraglyme (tetraethylene glycol dimethyl ether) plasma polymer. The tetraglyme polymer blocks virtually all non-specific binding of proteins, and it is non-adhesive for a fluorocarbon-polyethylene glycol (FC-PEG) surfactant designed to act as a 'hydrophobic anchor' for peptides. The surfactant shows a strong affinity for the fluorocarbon polymer pattern, thus enabling us to form a pattern of the surfactant-conjugated peptide. To verify this, we have synthesized a conjugate between histamine (as a model for a more complex peptide) and a commercially available FC-PEG surfactant. Disuccinimidyl carbonate was used to activate the terminal -OH group of the polyethylene glycol headgroup for the reaction with the amine-containing molecule. Affinity pattern formation can easily be achieved by immersion of the patterned substrates in a solution of the peptide-surfactant conjugate. Time of flight secondary ion mass spectroscopy in the imaging mode was used to verify that the surfactant localizes on the pattern, while the background remains bare. A model protein, bovine serum albumin, showed the same behavior. This suggests that these surfaces can be used for the formation of patterns of cell-adhesive proteins. These substrates will be used to investigate the influence of the cell size and shape of vascular smooth muscle cells on their physiology. PMID:11587038

Goessl, A; Golledge, S L; Hoffman, A S

2001-01-01

326

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

PubMed

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

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

2006-01-31

327

Reactions of laser-generated free radicals at semiconductor surfaces  

NASA Astrophysics Data System (ADS)

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

Steinfeld, Jeffrey I.

1990-01-01

328

Determining the electron temperature and the electron density by a simple collisional-radiative model of argon and xenon in low-pressure discharges  

NASA Astrophysics Data System (ADS)

A simple collisional-radiative model for argon and xenon is used, in conjunction with optical emission spectroscopy (line-ratio technique), to determine the electron temperature and electron density in low-pressure discharges containing argon and xenon. Satisfactory agreement is obtained between this method and the Langmuir probe for an inductively coupled plasma containing neon, argon and xenon. This method is applied for a capacitive discharge containing fluorocarbon, argon and xenon. The electron temperatures and electron densities obtained under various discharge conditions are compared with those reported in the literature by other techniques.

Zhu, Xi-Ming; Chen, Wen-Cong; Li, Jiang; Pu, Yi-Kang

2009-01-01

329

Feasibility study of a cryogenically cooled window for high-power gyrotrons  

NASA Astrophysics Data System (ADS)

Single-crystal sapphire is currently in use as the material for output windows in high-power microwave tubes, particularly gyrotrons. These windows are currently being cooled by fluorocarbon fluids at near-room temperatures. There are, however, several advantages in operating the window at very low temperatures: less absorption and consequent heating of the window, greater material strength, improved resistance to crack formation, greater thermal conductivity, and reduced thermal expansion. Operation at cryogenic temperatures is shown to be feasible. The output power, which is currently limited by window constraints, could be increased by an order of magnitude or more.

Haste, G. R.; Kimrey, H. D.; Prosise, J. D.

1986-07-01

330

Low-cost encapsulation materials for terrestrial solar cell modules  

NASA Technical Reports Server (NTRS)

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

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

1979-01-01

331

Study on the binding of trichloromonofluoromethane by bovine serum albumin using a fluorescent probe technique.  

PubMed

Protein binding of the aerosol propellant, trichloromonofluoromethane, was studied in bovine serum albumin (BSA) solutions using the fluorescent probe technique. The propellant displaced the probe, 8-anilino-1-naphthalenesulfonate, from its binding sites and reduced the fluorescence intensity. The binding association constants, the number of binding sites, and the competitive nature of the binding interaction were investigated. The hydrophobic nature of the binding and the implication of binding displacement interactions between the fluorocarbon and plasma-protein-bound drugs were also discussed. The fatty acid impurities present in the commercial BSA were found to have no effect on the protein binding of the propellant. PMID:986655

Peng, G W; Chiou, W L

1976-01-01

332

Exposure testing of solar collector plastic films  

NASA Astrophysics Data System (ADS)

The paper summarizes BEC experimental work aimed at finding low-cost long-life highly specular plastic films for solar collectors. Samples were subjected to up to 18 months of solar exposure in both real and accelerated testing techniques at a desert site in Arizona. The fluorocarbons Kynar and Tedlar exhibit the best weatherability characteristics of the materials tested. The polyester and polycarbonates studied have the problem of not being inherently resistant to UV degradation. Preliminary results from the thermoformed domes seem to indicate that they show self-cleaning characteristics.

Berry, M.; Dursch, H.

1980-09-01

333

Atomic Resolution Images of Solid-Liquid Interfaces  

NASA Astrophysics Data System (ADS)

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

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

1987-07-01

334

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

335

Perfluorocarbons and their use in cooling systems for semiconductor particle detectors  

Microsoft Academic Search

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

V. Vacek; G Hallewell; S Ilie; S Lindsay

2000-01-01

336

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.

337

Nano-particulate coating on cotton fabric through DBD  

NASA Astrophysics Data System (ADS)

Plasma polymerization of fluorocarbon was processed through dielectric barrier discharge (DBD). A thin hydrophobic film packed with nano-particulate structure was obtained on cotton fabric surface. The contact angle of the water and 1-bromonaphthalene on coated cotton fabric was 133° and 124° separately. The surface morphology of the coating was observed through SEM (Scanning Electronic Microscope). It was found that cotton fabric surface was tightly adhered to a thin film packed by nano-particles from 10nm to 200nm. This process showed potential applications in continuous coating of textiles with functional nano-particulate polymers, but without changing their softness performance.

Guo, Ying; Zhang, Jing; Xu, Jinzhou; Zhou, Rongming; Yu, Jianyong

2008-02-01

338

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

339

Atmospheric lifetime and annual release estimates for CFCl3 and CF2Cl2 from 5 years of ALE data  

NASA Astrophysics Data System (ADS)

CFCl3 and CF2Cl2 data for the 5-year period from July 1978-June 1983 are analyzed. The lifetime estimates are updated using the trend technique and the annual global release rates of the gases are derived. The effects of release uncertainties on lifetime estimates are examined by studying fluorocarbon data. It is observed that in 1981 the mixing ratios for CFCl3 and CF2Cl2 displayed increases of 8.8. and 15.3 pptv/year respectively, and the trend lifetime for CFCl13 is 74 + 31 or - 17 years and for CF2Cl2 111 + 222 or - 44 years.

Cunnold, D. M.; Alyea, F. N.; Prinn, R. G.; Rasmussen, R. A.; Simmonds, P. G.

1986-09-01

340

Atmospheric lifetime and annual release estimates for CFCl3 and CF2Cl2 from 5 years of ALE data  

NASA Technical Reports Server (NTRS)

CFCl3 and CF2Cl2 data for the 5-year period from July 1978-June 1983 are analyzed. The lifetime estimates are updated using the trend technique and the annual global release rates of the gases are derived. The effects of release uncertainties on lifetime estimates are examined by studying fluorocarbon data. It is observed that in 1981 the mixing ratios for CFCl3 and CF2Cl2 displayed increases of 8.8. and 15.3 pptv/year respectively, and the trend lifetime for CFCl13 is 74 + 31 or - 17 years and for CF2Cl2 111 + 222 or - 44 years.

Cunnold, D. M.; Alyea, F. N.; Prinn, R. G.; Rasmussen, R. A.; Simmonds, P. G.

1986-01-01

341

The Gas Pressure-dependent Contact Angle of Diamond-like Carbon Surface by SR Exposure Under Perfluorohexane(C6F14) Gas Atmosphere  

NASA Astrophysics Data System (ADS)

The contact angle on a diamond-like carbon (DLC) surface was controlled by synchrotron radiation (SR) under perfluorohexane (C6F14) gas atmosphere. It was found that the fluorocarbon group bonded to the DLC surface in the modified hydrophobic area from the measurement of X-ray photoelectron spectrum. The contact angle of a DLC surface was succeeded to increase from 73° to 116° by the SR irradiation with 400 mA?h at C6F14 gas pressure higher than 1.2 Pa.

Yamada, Noriko; Kato, Yuri; Kanda, Kazuhiro; Haruyama, Yuichi; Matsui, Shinji

2007-01-01

342

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

NASA Technical Reports Server (NTRS)

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

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

1978-01-01

343

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

DOEpatents

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

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

1991-01-01

344

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

345

The 1980 stratospheric-tropospheric exchange experiment  

NASA Technical Reports Server (NTRS)

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

Margozzi, A. P. (editor)

1983-01-01

346

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

Microsoft Academic Search

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

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

2006-01-01

347

Viscoelastic properties of elastomeric materials for O-ring applications  

NASA Technical Reports Server (NTRS)

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

Bower, Mark V.

1989-01-01

348

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

349

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

350

Low-noise polymeric nanomechanical biosensors  

NASA Astrophysics Data System (ADS)

A sensor device based on a single polymer cantilever and optical readout has been developed for detection of molecular recognition reactions without the need of a reference cantilever for subtraction of unspecific signals. Microcantilevers have been fabricated in the photoresist SU-8 with one surface passivated with a thin fluorocarbon layer. The SU-8 surface is sensitized with biological receptors by applying silanization methods, whereas the fluorocarbon surface remains inert to these processes. The thermal and mechanical properties of the chosen materials allow overcoming the main limitations of gold-coated silicon cantilevers: the temperature, pH, and ionic strength cross sensitivities. This is demonstrated by comparing the response of SU-8 cantilevers and that of gold-coated silicon nitride cantilevers to variations in temperature and pH. The sensitivity of the developed polymeric nanomechanical sensor is demonstrated by real-time detection of the human growth hormone with sensitivity in differential surface stress of about 1mN /m.

Calleja, Montserrat; Tamayo, Javier; Nordström, Maria; Boisen, Anja

2006-03-01

351

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

SciTech Connect

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

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

1992-01-01

352

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

353

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

SciTech Connect

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

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

1981-11-01

354

Chemiluminescence-based detection and comparison of protein amounts adsorbed on differently modified silica surfaces.  

PubMed

The biological consequences of protein adsorption on biomaterial surfaces are considered to be of utmost importance for their biocompatibility. A new method based on amino group-labeling coupled to a chemiluminescence reaction for direct determination of proteins adsorbed on material surfaces was employed. This method was used to explore the effects of surface chemistry and surface roughness on protein adsorption in a silicon oxide model system. Corundum sandblasting was applied to silicon wafers to create roughened surfaces while immobilization of fluorocarbon-, hydrocarbon-, and poly(ethylene glycol)-containing silanes produced surfaces of varying wettability. The adsorption behavior of two complex body fluids, human serum and saliva, and of two purified components, human serum albumin and fibronectin, was strongly influenced by the surface parameters. A general tendency to higher amounts of adsorbed protein was found on roughened surfaces and modification with poly(ethylene glycol) or with fluorocarbon moieties reduced protein adsorption. The values obtained with the new method could be confirmed by a colorimetric determination of protein amounts adsorbed on identically modified silica beads and were in accordance with those previously reported utilizing established methods for protein quantification. The presented method, which was methodically simple to perform and allowed the simultaneous measurement of a large number of samples, may be of future value for high-throughput surveying of the protein adsorption characteristics of biomaterials. PMID:17087913

Müller, Rainer; Hiller, Karl-Anton; Schmalz, Gottfried; Ruhl, Stefan

2006-12-15

355

Amorphous Silicon and Tungsten Etching Employing Environmentally Benign Plasma Process  

NASA Astrophysics Data System (ADS)

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

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

2001-02-01

356

Time resolved QCLAS measurements in pulsed cc-rf CF4/H2 plasmas  

NASA Astrophysics Data System (ADS)

Fluorocarbon containing capacitively coupled radio frequency (cc-rf) plasmas are widely used in technical applications and as model systems for fundamental investigations of complex plasmas. Absorption spectroscopy based on pulsed quantum cascade lasers (QCL) was applied in the mid-IR spectral range of 1269-1275 cm-1. Absolute densities of the precursor molecule CF4 and of the stable product C3F8 were measured with a time resolution of up to 1 ms in pulsed CF4/H2 asymmetrical cc-rf (13.56 MHz) discharges. For this purpose both the non-negligible temperature dependence of the absorption coefficients and the interference of the absorption features of CF4 and C3F8 had to be taken into account in the target spectral range. Therefore, at two different spectral positions composite absorption spectra were acquired under the same plasma conditions in order to discriminate between CF4 and C3F8 contributions. A total consumption of~ 12 % was observed for CF4 during a 1 s plasma pulse, whereas C3F8 appeared to be produced mainly from amorphous fluorocarbon layers deposited at the reactor walls. A gas temperature increase by ~ 100 K in the plasma pulse was estimated from the measurements. Additionally, not yet identified unresolved absorption (potentially from the excited CF4 molecule) was found during the àon-phase'.

Stepanov, S.; Welzel, S.; Röpcke, J.; Meichsner, J.

2009-03-01

357

Comparative Studies of Perfluorocarbon Alternative Gas Plasmas for Contact Hole Etch  

NASA Astrophysics Data System (ADS)

Saturated perfluorocarbons (PFCs) such as CF4, C2F6, C3F8 and c-C4F8 are used as dry-etch gases in the semiconductor industry. They have a significant greenhouse effect. Unsaturated fluorocarbons can be alternated with these PFCs because of their easy decomposition in the atmosphere. The authors have diagnosed the plasmas generated from straight-chain unsaturated gases such as C3F6, C4F6, C4F8 and C5F8 in an inductively coupled plasma reactor and have compared their etch properties. It was found that high selectivity has been obtained in a C4F6 or C5F8 plasma without mixing any specific gases. Fine contact holes of approximately 100 nm in diameter also have been obtained using C4F6 or C5F8 with or without adding Ar or O2. These good etch properties of C4F6 and C5F8 have been achieved as a consequence of the appropriate balance between the lower density of fluorocarbon polymers and the dominant etching species CF+ with lower etching efficiency. It can be concluded that C4F6 and C5F8 can be used as PFC replacements for the dry-etch gas.

Nakamura, Shingo; Itano, Mitsushi; Aoyama, Hirokazu; Shibahara, Kentaro; Yokoyama, Shin; Hirose, Masataka

2003-09-01

358

Retention perturbations due to particle-wall interactions in sedimentation field-flow fractionation  

SciTech Connect

In this paper theoretical and experimental results are obtained relating to the perturbation in retention in sedimentation field-flow fractionation due to particle-wall electrostatic and van der Waals interactions. These perturbations are described in relationship to standard retention theory, an ideal theory whose basic assumptions are summarized. A general equation in integral form is given for retention ratio R, and it is shown how the standard retention theory and sterically corrected retention theory are thereby obtained. Expressions are given for the potential energy of a colloidal particle near a wall resulting from electrostatic and van der Waals interactions; these interactions alter the concentration profile in the field-flow fractionation channel in a way that requires numerical integration to get R. By the use of estimated interaction parameters, R is plotted against field strength and ionic strength for several wall materials including stainless steel and fluorocarbon resin. Experimental results are reported for five different carrier solutions including distilled water. The agreement between theory and experimental results is very good considering the approximate nature of the parameters used. Both the calculations and the measurements show that the retentive perturbations are smaller for fluorocarbon resin than for stainless steel, Hastelloy C, and polyimide surfaces. An intermediate ionic strength also appears to be optimal. A new separation technique based on the combination of field-flow fractionation and potential barrier chromatography is suggested, and its possible advantages are discussed.

Hansen, M.E.; Giddings, J.C. (Univ. of Utah, Salt Lake City (USA))

1989-04-15

359

Stick-slip of the three-phase line in measurements of dynamic contact angles.  

PubMed

Contact angles of a series of n-alkanes (i.e., n-heptane to n-hexadecane) are studied on two functionalized maleimide copolymers (i.e., poly(ethene-alt-N-(4-(perfluoroheptylcarbonyl)aminobutyl)maleimide) (ETMF) and poly(octadecene-alt-N-(4-(perfluoroheptylcarbonyl)aminobutyl)maleimide) (ODMF)). On the homogeneous ETMF films, all liquids show a smooth motion of the three-phase line. In contrast, on ODMF surfaces that are found to consist of mainly fluorocarbons and small patches of hydrocarbons, short-chain n-alkanes show a stick-slip pattern. By increasing the chain length of the probe liquids, stick-slip is reduced significantly. The phenomenon is discussed in the framework of the Cassie equation. It is found that the upper limit of contact angles in the stick-slip pattern is given by the advancing angle that would be obtained on the pure fluorocarbon surface, whereas the lower limit of the stick-slip pattern is given by the Cassie angle. PMID:16401111

Tavana, Hossein; Yang, Guocheng; Yip, Christopher M; Appelhans, Dietmar; Zschoche, Stefan; Grundke, Karina; Hair, Michael L; Neumann, A Wilhelm

2006-01-17

360

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

361

Head material effects on interface tribochemistry  

NASA Astrophysics Data System (ADS)

Sliding experiments between sliders made of different materials and magnetic thin-film disks were performed in a vacuum and an ambient in order to shed light on material effects in tribology. Al2O3-TiC, amorphous silicon, amorphous carbon, MnZn ferrite, and sapphire were chosen for their current or potential use as head substrate materials. In ambient, the amorphous carbon performed the best tribologically while Al2O3-TiC the worst. The wear mechanism of the slider-disk interface was studied in-situ by mass spectrometry and frictional measurements. For unlubricated interfaces, decreasing evolution of C, CO and CO2 during initial sliding was accompanied by decreasing friction. For lubricated interfaces, fluorocarbon fragments with a wide range of masses were generated at a decreasing rate while friction was low and relatively constant. When the magnitude of gaseous signals increased, frictional variations rose dramatically, hydrogen evolution followed with some delay, and a wear track was formed. With amorphous silicon sliders, a significant amount of SiF4 was detected which indicates a tribochemical reaction between SiO2 surface and HF that was produced by the scissioning of lubricants. Degradation mechanisms are dominated by removal of surface groups and adsorbates from solid surfaces and by scission, losses and alteration of fluorocarbon polymers.

Pan, Xiaohe; Novotny, V. J.

1994-03-01

362

Synthesis and characterization of self-assembling water-soluble polymers  

SciTech Connect

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

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

1992-05-01

363

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

364

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

PubMed

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

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

2012-09-26

365

Theoretical prediction of thermochemistry and kinetics of flurocarbons  

SciTech Connect

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

Zachariah, M.R.; Burgess, D. Jr.; Tsang, W. [National Institute of Standards and Technology, Gaithersburg, MD (United States)] [and others

1995-12-31

366

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

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

367

Detection of Chamber Conditioning by CF4 in the GEC Cell  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

368

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

369

Corrosion of current-collector materials in Li-ion cells  

SciTech Connect

The primary current-collector materials being used in lithium-ion cells are susceptible to environmental degradation: aluminum to pitting corrosion and copper to environmentally assisted cracking. Pitting occurs at the highly oxidizing potentials associated with the positive-electrode charge condition. However, the pitting mechanism is more complex than that typically observed in aqueous systems in that the pits are filled with a mixed metal/oxide product and exist as mounds or nodules on the surface. Electrochemical impedance was shown to be an effective analytical tool for quantification and verification of visual observations and trends. Two fluorocarbon-based coatings were shown to improve the resistance of Al to localized pitting. Finally, environmental cracking of copper can occur at or near the lithium potential and only if specific metallurgical conditions exist (work hardening and large grain size).

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

1996-12-01

370

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

371

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

372

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

373

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

374

Optical plasma emission spectroscopy of etching plasmas used in Si-based semiconductor processing  

NASA Astrophysics Data System (ADS)

Previously published applications of optical emission spectroscopy as a quantitative plasma diagnostic technique are reviewed. By adding traces of rare gases to the plasma, electron temperatures (Te) and relative electron and ion densities can be determined from electron impact-induced optical emission. Excitation from both the ground state and metastable states of the rare gases must be considered. At higher rare gas partial pressures, UV radiation trapping and optical cascading must also be taken into account. Absolute species concentrations (e.g. Cl2, Cl, O, and F) can be derived from their optical emissions, combined with Te measurements determined from rare gas optical emission. Examples are given of neutral and ion species density measurements in chlorine, oxygen, and fluorocarbon-containing low-pressure, high charge-density plasmas. Typical results of Te measurements are also presented and compared with Langmuir probe measurements.

Donnelly, V. M.; Malyshev, M. V.; Schabel, M.; Kornblit, A.; Tai, W.; Herman, I. P.; Fuller, N. C. M.

2002-08-01

375

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

376

Effects of tacky mat contamination on bond degradation for Chemlok/liner and NBR/liner bonds  

NASA Technical Reports Server (NTRS)

Tacky mats are placed by the rubber lay-up areas for the solid rocket motor segments. These mats dust off the shoes prior to entering the platform where the lay-up work is performed. The possibility exists that a tacky mat could be touched with gloved hands prior to handling the uncured nitride butadiene rubber (NBR). Tests were run to determine if NBR were accidentally touched would there be any degradation of the liner/NBR bond. The tacky mats were judged solely on the basis of bond degradation caused by either direct or indirect contamination. Test results all indicate that there was no notable NBR/Chemlok or liner/NBR bond degradation on samples that came into contact with the tacky mat material. Testing procedures are described. The tacky mat adhesive composition does not contain fluorocarbons or release agents that would affect bonding.

Padilla, A. M.

1989-01-01

377

A fluorinated detergent for membrane-protein applications.  

PubMed

Surfactants carrying fluorocarbon chains hold great promise as gentle alternatives to conventional hydrocarbon-based detergents for the solubilization and handling of integral membrane proteins. However, their inertness towards lipid bilayer membranes has limited the usefulness of fluorinated surfactants in situations where detergent-like activity is required. We demonstrate that fluorination does not necessarily preclude detergency, as exemplified by a fluorinated octyl maltoside derivative termed F6 OM. This nonionic compound readily interacts with and completely solubilizes phospholipid vesicles in a manner reminiscent of conventional detergents without, however, compromising membrane order at subsolubilizing concentrations. Owing to this mild and unusual mode of detergency, F6 OM outperforms a lipophobic fluorinated surfactant in chaperoning the functional refolding of an integral membrane enzyme by promoting bilayer insertion in the absence of micelles. PMID:25753129

Frotscher, Erik; Danielczak, Bartholomäus; Vargas, Carolyn; Meister, Annette; Durand, Grégory; Keller, Sandro

2015-04-20

378

Development of a custom on-line ultrasonic vapour analyzer/flowmeter for the ATLAS inner detector, with application to gaseous tracking and Cherenkov detectors  

E-print Network

Precision sound velocity measurements can simultaneously determine binary gas composition and flow. We have developed an analyzer with custom electronics, currently in use in the ATLAS inner detector, with numerous potential applications. The instrument has demonstrated ~0.3% mixture precision for C3F8/C2F6 mixtures and < 10-4 resolution for N2/C3F8 mixtures. Moderate and high flow versions of the instrument have demonstrated flow resolutions of +/- 2% F.S. for flows up to 250 l.min-1, and +/- 1.9% F.S. for linear flow velocities up to 15 ms-1; the latter flow approaching that expected in the vapour return of the thermosiphon fluorocarbon coolant recirculator being built for the ATLAS silicon tracker.

R. Bates; M. Battistin; S. Berry; J. Berthoud; A. Bitadze; P. Bonneau; J. Botelho-Direito; N. Bousson; G. Boyd; G. Bozza; E. Da Riva; C. Degeorge; B. DiGirolamo; M. Doubek; J. Godlewski; G. Hallewell; S. Katunin; D. Lombard; M. Mathieu; S. McMahon; K. Nagai; E. Perez-Rodriguez; C. Rossi; A. Rozanov; V. Vacek; M. Vitek; L. Zwalinski

2012-10-30

379

Monolithic polymer microlens arrays with high numerical aperture and high packing density.  

PubMed

This work reports a novel method for monolithic fabrication of high numerical aperture polymer microlens arrays (high-NA MLAs) with high packing density (PD) at wafer level. The close-packed high-NA MLAs were fabricated by incorporating conformal deposition of ultrathin fluorocarbon nanofilm and melting the cylindrical polymer islands. The NA and PD of hemispherical MLAs with a hexagonal arrangement increase up to 0.6 and 89%, respectively. The increase of NA enhances the lens transmission securing the beam width down to 1.1 ?m. The close-packed high-NA MLAs enable high photon collection efficiency with signal-to-noise ratio greater than 50:1. PMID:25612820

Jung, Hyukjin; Jeong, Ki-Hun

2015-02-01

380

Volatile organic components in the Skylab 4 spacecraft atmosphere.  

PubMed

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 of 58 to 592 were identified by mass spectrometry. Besides components known from other environments, such as alkanes, alkenes, and alkylated aromatic hydrocarbons, components typical for the human metabolism such as ketones and alcohols were found. Other typical components in the spacecraft atmosphere are fluorocarbons (freons) and various silicone compounds, mostly normal and cyclic methylsiloxanes. PMID:240349

Liebich, H M; Bertsch, W; Zlatkis, A; Schneider, J

1975-08-01

381

Glazings 101  

SciTech Connect

A brief introduction to the solar industry is given with an analogy to the auto industry. Desired characteristics of glazing are listed and comparisons are made between glass and plastic glazing. The characteristics of each type of plastic used in glazing are discussed in the light of application for solar direct gain. Comparisons of glazing material are presented in a chart which includes: (1) glass; (2) acrylic; (3) polycarbonate; (4) fiber reinforced polyester; (5) laminate (acrylic polyester); (6) polyethylene; (7) polyester; (8) fluorocarbons; and (9) silicone treated cloth. For each general type of glazing, the trade names, comments, thickness, solar transmittance, infrared transmittance, maximum operating temperature, estimated lifetime, cost/ft/sup 2/, transparent or translucent, and lbs/ft/sup 2/ are given. Advantages and disadvantages are given for each product. 4 references. (MJJ)

Kensil, D.

1980-09-01

382

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 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 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

383

Development of a custom on-line ultrasonic vapour analyzer/flowmeter for the ATLAS inner detector, with application to gaseous tracking and Cherenkov detectors  

E-print Network

Precision sound velocity measurements can simultaneously determine binary gas composition and flow. We have developed an analyzer with custom electronics, currently in use in the ATLAS inner detector, with numerous potential applications. The instrument has demonstrated ~0.3% mixture precision for C3F8/C2F6 mixtures and C3F8 mixtures. Moderate and high flow versions of the instrument have demonstrated flow resolutions of +/- 2% F.S. for flows up to 250 l.min-1, and +/- 1.9% F.S. for linear flow velocities up to 15 ms-1; the latter flow approaching that expected in the vapour return of the thermosiphon fluorocarbon coolant recirculator being built for the ATLAS silicon tracker.

Bates, R; Berry, S; Berthoud, J; Bitadze, A; Bonneau, P; Botelho-Direito, J; Bousson, N; Boyd, G; Bozza, G; Da Riva, E; Degeorge, C; DiGirolamo, B; Doubek, M; Godlewski, J; Hallewell, G; Katunin, S; Lombard, D; Mathieu, M; McMahon, S; Nagai, K; Perez-Rodriguez, E; Rossi, C; Rozanov, A; Vacek, V; Vitek, M; Zwalinski, L

2013-01-01

384

Design and prototype studies of the TOTEM Roman pot detectors  

NASA Astrophysics Data System (ADS)

The Roman pots of the TOTEM experiment at LHC will be equipped with edgeless silicon micro-strip detectors. A detector package consists of 10 detector planes cooled at -15C in vacuum. The detector resolution is 20 ?m, the overall alignment precision has to be better than 30 ?m. The detector planes are composed of a kapton hybrid glued on a substrate made of low expansion alloy, CE07 with 70% Si and 30% Al. An evaporative cooling system based on the fluorocarbon C3F8 with oil-free compressors has been adopted. The throttling of the fluid is done locally through capillaries. A thermo-mechanical prototype has been assembled. The results fully match the requirements and the expectations of calculations. They show a low thermal gradient on the cards and a uniform temperature distribution over the 10 planes.

Oriunno, Marco; Battistin, Michele; David, Eric; Guglielmini, Paolo; Joram, Christian; Radermacher, Ernst; Ruggiero, Gennaro; Wu, Jihao; Vacek, Vaclav; Vins, Vaclav

2007-10-01

385

Development of a custom on-line ultrasonic vapour analyzer/flowmeter for the ATLAS inner detector, with application to gaseous tracking and Cherenkov detectors  

NASA Astrophysics Data System (ADS)

Precision sound velocity measurements can simultaneously determine binary gas composition and flow. We have developed an analyzer with custom electronics, currently in use in the ATLAS inner detector, with numerous potential applications. The instrument has demonstrated ~ 0.3% mixture precision for C3F8/C2F6 mixtures and < 10-4 resolution for N2/C3F8 mixtures. Moderate and high flow versions of the instrument have demonstrated flow resolutions of ± 2% of full scale for flows up to 250 l min-1, and ± 1.9% of full scale for linear flow velocities up to 15 m s-1 the latter flow approaching that expected in the vapour return of the thermosiphon fluorocarbon coolant recirculator being built for the ATLAS silicon tracker.

Bates, R.; Battistin, M.; Berry, S.; Berthoud, J.; Bitadze, A.; Bonneau, P.; Botelho-Direito, J.; Bousson, N.; Boyd, G.; Bozza, G.; Da Riva, E.; Degeorge, C.; DiGirolamo, B.; Doubek, M.; Godlewski, J.; Hallewell, G.; Katunin, S.; Lombard, D.; Mathieu, M.; McMahon, S.; Nagai, K.; Perez-Rodriguez, E.; Rossi, C.; Rozanov, A.; Vacek, V.; Vitek, M.; Zwalinski, L.

2013-01-01

386

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

NASA Technical Reports Server (NTRS)

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

Kendall, B. R. F.

1983-01-01

387

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

NASA Technical Reports Server (NTRS)

A contaminant is any material or substance which is potentially undesirable or which may adversely affect any part, component, or assembly. Contamination control of SRM hardware surfaces is a serious concern, for both Thiokol and NASA, with particular concern for contaminants which may adversely affect bonding surfaces. The purpose of this study is to develop laboratory analytical techniques which will make it possible to certify the cleanliness of any designated surface, with special focus on particulates (dust, dirt, lint, etc.), oils (hydrocarbons, silicones, plasticizers, etc.), and greases (HD-2, fluorocarbon grease, etc.). The hardware surfaces of concern will include D6AC steel, aluminum alloys, anodized aluminum alloys, glass/phenolic, carbon/phenolic, NBR/asbestos-silica, and EPDM rubber.

Law, R. D.

1989-01-01

388

Role of Hydrogen in Dry Etching of Silicon Carbide Using Inductively and Capacitively Coupled Plasma  

NASA Astrophysics Data System (ADS)

We investigated the etching mechanism of SiC using inductively and capacitively coupled plasma with CHF3 and SF6 gases. We discussed the effects of O2 and H2 gases on etching properties. By optimizing the conditions of H2 flow rate, we could confirm the improvement in etching rates. Surface roughness was also improved by the optimum addition of H2 gas. Analysis by XPS revealed that a fluorocarbon film was formed on the surface after etching with SF6 gas. Surface fluoride atomic concentration was reduced from 28 to 8 at.% by the addition of H2 gas. A H2 annealing suppressed the fluoride concentration of surface to less than 3 at.%. This processing technique is very effective for the fabrication of SiC devices.

Mikami, Hidenori; Hatayama, Tomoaki; Yano, Hiroshi; Uraoka, Yukiharu; Fuyuki, Takashi

2005-06-01

389

Small-Angle Scattering and Electron Microscopy Investigation of Nanotubules Made from a Perfluoroalkylated Glucophospholipid.  

PubMed

Anionic glucophospholipids were recently reported as a new family of tubule-forming lipids. We report here investigations on the structure of nanotubules made from a glucophospholipid with a mixed fluorocarbon-hydrocarbon hydrophobe, using freeze fracture and cryo-transmission electron microscopy (TEM) and X-ray and neutron small angle scattering (SAXS, SANS). The hollow and regularly shaped tubules are very thin: they have an external radius of 140 Å and an internal radius of 35 Å on the average. Their 105 Å-thick wall appears to consist in three bilayers in which the glucophospholipid molecules are probably in a tilted and/or interdigitated configuration. Upon heating these nanotubes convert reversibly into vesicles; transformation is complete at 60 degrees C. Copyright 1999 Academic Press. PMID:10092363

Imae; Funayama; Krafft; Giulieri; Tada; Matsumoto

1999-04-15

390

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

391

The effects of specified chemical meals on food intake.  

PubMed

Rats received intragastric infusions of various specified chemical meals and were subsequently tested for a reduction in food intake. A second experiment, using a novel technique, tested for conditioned aversion to the meal infusions. The nonnutritive substances, kaolin clay and emulsified fluorocarbon, had no significant effect on food intake. Infusions of 1 M glucose and 1 M sorbitol reduced feeding behavior, but the 1 M sorbitol infusion also produced a conditioned aversion to flavored pellets paired with the sorbitol infusion, showing that the reduced feeding could have been caused by discomfort. Infusion of a high-fat meal consisting of emulsified triolein mixed with small amounts of sugar and protein or the rat's normal liquid diet, Nutrament, also reduced food intake, and both infusions failed to produce a conditioned aversion. The use of specified meals to understand the chemical basis of satiety requires a sensitive behavioral test to establish that the meal does not cause discomfort or other nonspecific effects. PMID:707387

Koopmans, H S; Maggio, C A

1978-10-01

392

Fine Contact Hole Etching in Magneto-Microwave Plasma  

NASA Astrophysics Data System (ADS)

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

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

1994-04-01

393

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

NASA Astrophysics Data System (ADS)

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

394

Electrical conduction control of carbon nanowalls  

SciTech Connect

The electrical conduction behavior of carbon nanowalls (CNWs) has been evaluated by Hall measurement. CNWs, which comprise stacks of graphene sheets standing on the substrate, are fabricated by fluorocarbon/hydrogen plasma enhanced chemical vapor deposition. We have investigated the effect of N{sub 2} addition to C{sub 2}F{sub 6}/H{sub 2} system on the electrical properties of CNWs. The CNWs grown with the C{sub 2}F{sub 6}/H{sub 2} plasma exhibit p-type conduction. As a result of the nitrogen inclusion in the CNWs, the conduction type of the CNWs changes to n type. The carrier concentration is controllable by changing the flow rate of the additional N{sub 2} during the CNW growth process.

Takeuchi, Wakana; Ura, Masato; Hori, Masaru [Department of Electrical Engineering and Computer Science, Nagoya University, Chikusa, Nagoya 468-8603 (Japan); Hiramatsu, Mineo [Department of Electrical and Electronic Engineering, Meijo University, Tempaku, Nagoya 468-8502 (Japan); Tokuda, Yutaka [Department of Electrical and Electronics Engineering, Aichi Institute of Technology, Yakusa, Toyota 470-0392 (Japan); Kano, Hiroyuki [NU Eco-Engineering Co., Ltd., Kurozasa, Miyoshi, Nishikamo 470-0201 (Japan)

2008-05-26

395

The wettability of fluoropolymer surfaces: influence of surface dipoles.  

PubMed

The wettabilities of fluorinated polymers were evaluated using a series of contacting probe liquids ranging in nature from nonpolar aprotic to polar aprotic to polar protic. Fully fluorinated polymers were wet less than partially fluorinated polymers, highlighting the weak dispersive interactions of fluorocarbons. For partially fluorinated polymers, the interactions between the distributed dipoles along the polymer backbone and the dipoles of the contacting liquids were evaluated using both polar and nonpolar probe liquids. The results demonstrate that the surface dipoles of the fluoropolymers generated by substituting fluorine atoms with hydrogen or chlorine atoms can strongly interact with polar contacting liquids. The wettabilities of the partially fluorinated polymers were enhanced by increasing the density of dipoles across the surfaces and by introducing differentially distributed dipoles. PMID:18393484

Lee, Sangwha; Park, Joon-Seo; Lee, T Randall

2008-05-01

396

Alternative training agents, phase 1. Survey of near-term candidate fire extinguishing agents and predicting properties of halocarbon mixtures, volume 1  

NASA Astrophysics Data System (ADS)

In this report, 14 compounds are examined as potential near-term candidates for alternative firefighter training agents for streaming applications. This list consists of suitable fluorine-containing compounds (primarily fluorocarbons, hydrofluorocarbons, and hydrochlorofluorocarbons) known to have had significant toxicity testing completed, with bulk production capabilities existing in the past, present, or anticipated near future. Many of these compounds are being produced or considered as replacements for chlorofluorocarbons (CFCs) in refrigeration and foam-blowing applications. The ozone depletion potential, global warming potential, stage of toxicity testing, toxicity, availability, and relative cost of each compound are discussed. Physical and thermodynamic properties and estimated and measured flame suppression concentrations are reported. Those compounds that have low toxicity (with significant testing completed) are available in bulk and have desirable properties are discussed in detail. It is recommended that HCFC-123 be tested both in pure form and in blends as potential replacement training agents. Twelve blends are recommended for fire suppression.

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

1991-02-01

397

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

398

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.

399

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

400

Restoring Susceptibility Induced MRI Signal Loss in Rat Brain at 9.4 T: A Step towards Whole Brain Functional Connectivity Imaging  

PubMed Central

The aural cavity magnetic susceptibility artifact leads to significant echo planar imaging (EPI) signal dropout in rat deep brain that limits acquisition of functional connectivity fcMRI data. In this study, we provide a method that recovers much of the EPI signal in deep brain. Needle puncture introduction of a liquid-phase fluorocarbon into the middle ear allows acquisition of rat fcMRI data without signal dropout. We demonstrate that with seeds chosen from previously unavailable areas, including the amygdala and the insular cortex, we are able to acquire large scale networks, including the limbic system. This tool allows EPI-based neuroscience and pharmaceutical research in rat brain using fcMRI that was previously not feasible. PMID:25844644

Li, Rupeng; Liu, Xiping; Sidabras, Jason W.; Paulson, Eric S.; Jesmanowicz, Andrzej; Nencka, Andrew S.; Hudetz, Anthony G.; Hyde, James S.

2015-01-01

401

Development and evaluation of elastomeric materials for geothermal applications  

NASA Technical Reports Server (NTRS)

A material for a casing packer for service for 24 hours in a geothermal environment was developed by synthesis of new elastomers and formulation of available materials. Formulation included use of commercial elastomer gumstocks and also crosslinking of plastic (high Tg) materials. Fibrous reinforcement of fluorocarbon rubbers was emphasized. Organic fiber reinforcement did not increase hot properties significantly. Glass fiber reinforcement gave significant increase in tensile properties. Elongation was reduced, and the glass-reinforced composition examined so far did not hold up well in the geothermal environment. Colloidal asbestos fibers were also investigated. A few experiments with polyphenyl ether gave material with low tensile and high compression set. Available high styrene SBR compositions were studied. Work to date suggests that new synthetic polymers will be required for service in geothermal environments.

Mueller, W. A.; Kalfayan, S. H.; Reilly, W. W.; Ingham, J. D.

1978-01-01

402

Development of a high-efficiency, gas-fired, heat pipe, warm-air heating system  

NASA Astrophysics Data System (ADS)

With the introduction by Borg-Warner of the Heatpipe Furnace, one of the major goals of this program was achieved. This milestone was reached after a 105,000 Btu/hr, 85 percent efficient manufacturing prototype heat pipe furnace was designed, fabricated, and tested by Thermo Electron. Other prototype units of different capacities were also designed. The prototypes underwent extensive field testing and in-house accelerated life-cycle testing, indicating that they were reliable, safe, and cost-competitive. Specific issues like freeze protection and oil contamination were addressed. Two different prototype ultrahigh-efficiency condensing furnaces were designed, fabricated and tested. One approach utilized a fluorocarbon-filled heat pipe as a secondary-stage heat exchanger; the other used a plate finned tube coil as the heat exchanger.

Feldman, S.; Becker, F.

1985-01-01

403

An e.s.c.a. study of atomic oxygen interactions with phosphazene-coated polyimide films  

NASA Technical Reports Server (NTRS)

Metallic as well as most nonmetallic materials experience oxidation and mass loss via surface erosion in low earth orbit as shown in previous Space Shuttle flights. This study is an evaluation of select polyphosphazene polymers and their resistance to atomic oxygen attack. Electron spectroscopy for chemical analysis examinations of the surfaces of polyphosphazene coatings were monitored for microstructural changes induced during exposures to atomic oxygen. Sample exposures in oxygen plasmas and O(3P) beam were compared as to their effect on surface compositional changes in the polyphosphazene coating. High resolution line scans revealed rearrangements in the polymer backbone and scissioning reactions involving fluorocarbon units of long chain fluoroalkoxy pendant groups. Atom percents and peak areas of all species provided a detailed profile of the microstructural changes induced in phosphazene polymers as a result of exposures to atomic oxygen.

Fewell, Larry L.; Finney, Lorie

1991-01-01

404

The Effect of Supercritical Fluids on Solid Acid Catalyst Alkylation  

SciTech Connect

The alkylation of isobutane with trans-2-butene was explored over six solid acid catalysts in the liquid, near-critical liquid, and supercritical regions through the addition of an inert cosolvent to the reaction feed mixture. The addition of supercritical cosolvents did not result in sustained catalytic alkylation activity. A modest improvement in product yield was obtained with the addition of methane in the modified-liquid region; however, catalyst longevity and product selectivity were decreased compared to cosolvent-free liquid conditions. This paper describes the catalyst screening and selection process, an exploration of catalyst performance with varying concentrations of methane, and an examination of the effects of seven supercritical fluids on catalyst performance. The catalysts included two zeolites, two sulfated metal oxides, and two Nafion catalysts. Three hydrocarbons, two fluorocarbons, carbon dioxide, and sulfur hexafluoride were explored as inert cosolvents added to the reaction mixture.

Ginosar, Daniel Michael; Thompson, David Neil; Burch, Kyle Coates; Zalewski, D. J.

2002-05-01

405

Laboratory Studies of Chemical and Photochemical Processes Relevant to Stratospheric Ozone  

NASA Technical Reports Server (NTRS)

The purpose of this project is to reduce the uncertainty in several key gas-phase kinetic processes which impact our understanding of stratospheric ozone. The main emphasis of this work is on measuring rate coefficients and product channels for reactions of HOx and NOx species in the temperature range 200 K to 240 K relevant to the lower stratosphere. Other areas of study have included infrared spectroscopic studies of the HO radical, measurements of OH radical reactions with alternative fluorocarbons, and determination of the vapor pressures of nitric acid hydrates under stratospheric conditions. The results of these studies will improve models of stratospheric ozone chemistry and predictions of perturbations due to human influences.

Zahniser, Mark S.; Nelson, David D.; Worsnop, Douglas R.; Kolb, Charles E.

1996-01-01

406

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

NASA Technical Reports Server (NTRS)

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 about 2 x 10 to the 12th 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.

1987-01-01

407

Direct determination of surface tension in the lung.  

PubMed Central

We have used the spreading behavior of small drops of several fluorocarbon fluids and silicone oil on air-liquid interfaces to measure the surface tension of lungs in situ. The test fluids were calibrated in a surface balance at 37 degrees on monolayers of dipalmitoylphosphatidylcholine. At particular surface tensions characteristic of each fluid used, an increase in the tension of 1 mN/m or less caused the droplets to spread reversibly from a sphere to a lens shape. Using micropipettes we placed such droplets on the alveolar surfaces of excised rat lungs held at functional residual capacity and 37 degrees and found that the surface tension remained below 9 mN/m for at least 30 min. The surface tension-volume relationship was linear for tensions ranging from 9 to 20 mN/m. Images PMID:1070020

Schürch, S; Goerke, J; Clements, J A

1976-01-01

408

Resolution of contamination problems affecting laser surface certification inspection  

NASA Astrophysics Data System (ADS)

Contamination from particulate and organic residues which interfered, with the laser surface certification (LSC) inspection of some parts was found to come from three sources: particulate and organic residues from polishing compounds; organic films from cleaning solvents; and particles and organic residues transferred from plastic fixtures used to process these parts. The manufacturing cleaning process was not effective in removing all polishing compound residues, and an extensive cleaning procedure was developed using two solvents in a multicycle ultrasonic/vapor degreasing procedure. Parts were then subjected to gas plasma cleaning which removed the organic films left by the solvent cleaning. Plastic and rubber materials were evaluated for their contamination transfer characteristics; a fluorocarbon elastomer was the least contaminating. Inspection data established the efficacy of the cleaning procedure. After design relaxation, a single stage ultrasonic vapor degreasing process was used to achieve product acceptance.

Jackson, L. C.

1982-03-01

409

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

NASA Astrophysics Data System (ADS)

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 about 2 x 10 to the 12th 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

410

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

411

Cathodic electrocatalyst layer for electrochemical generation of hydrogen peroxide  

NASA Technical Reports Server (NTRS)

A cathodic gas diffusion electrode for the electrochemical production of aqueous hydrogen peroxide solutions. The cathodic gas diffusion electrode comprises an electrically conductive gas diffusion substrate and a cathodic electrocatalyst layer supported on the gas diffusion substrate. A novel cathodic electrocatalyst layer comprises a cathodic electrocatalyst, a substantially water-insoluble quaternary ammonium compound, a fluorocarbon polymer hydrophobic agent and binder, and a perfluoronated sulphonic acid polymer. An electrochemical cell using the novel cathodic electrocatalyst layer has been shown to produce an aqueous solution having between 8 and 14 weight percent hydrogen peroxide. Furthermore, such electrochemical cells have shown stable production of hydrogen peroxide solutions over 1000 hours of operation including numerous system shutdowns.

Rhodes, Christopher P. (Inventor); Tennakoon, Charles L. K. (Inventor); Singh, Waheguru Pal (Inventor); Anderson, Kelvin C. (Inventor)

2011-01-01

412

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

413

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

NASA Technical Reports Server (NTRS)

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

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

2013-01-01

414

Ultrastructural study of the effects of trichlorotrifluoroethane on the liver of hairless mice.  

PubMed

Fluorocarbon 113 was applied to the backs of male hairless mice for 10 days, 20 days and 40 days. After each exposure period, the mice were anesthetized and the liver biopsied. The tissue was prepared for light and electron microscopy. The resultant micrographs were stereologically analyzed. N differences in mitochondrial structure were observed between the controls and the animals exposed for 10 days and 40 days. In the animals exposed for 20 days, the mitochondria appeared swollen with a loss of matrix and cristae and a breakdown of one of the mitochondrial membranes. Stereological analysis demonstrated a significant increase in mitochondrial volume in the 20 day exposure group. The relative volume of the endoplasmic reticulum increased significantly over the controls in the animals exposed for 10 days, 20 days and 40 days based on stereological analysis. PMID:6854691

McKnight, J E; McGraw, J L

1983-04-01

415

Extraction studies. Final report, May 6, 1996--September 30, 1997  

SciTech Connect

During the first week of this effort, an Alpkem RFA-300 4-channel automated chemical analyzer was transferred to the basement of building 42 at TA-46 for the purpose of performing extraction studies. Initially, this instrumentation was applied to soil samples known to contain DNA. Using the SFA (Segmented Flow Analysis) technique, several fluidic systems were evaluated to perform on-line filtration of several varieties of soil obtained from Cheryl Kuske and Kaysie Banton (TA-43, Bldg. 1). Progress reports were issued monthly beginning May 15, 1996. Early in 1997 there was a shift from the conventional 2-phase system (aqueous + air) to a 3-phase system (oil + aqueous + air) to drastically reduce sample size and reagent consumption. Computer animation was recorded on videotape for presentations. The time remaining on the subcontract was devoted to setting up existing equipment to incorporate the 3rd phase (a special fluorocarbon oil obtained from DuPont).

NONE

1997-10-09

416

Spacecraft dielectric material properties and spacecraft charging  

NASA Technical Reports Server (NTRS)

The physics of spacecraft charging is reviewed, and criteria for selecting and testing semiinsulating polymers (SIPs) to avoid charging are discussed and illustrated. Chapters are devoted to the required properties of dielectric materials, the charging process, discharge-pulse phenomena, design for minimum pulse size, design to prevent pulses, conduction in polymers, evaluation of SIPs that might prevent spacecraft charging, and the general response of dielectrics to space radiation. SIPs characterized include polyimides, fluorocarbons, thermoplastic polyesters, poly(alkanes), vinyl polymers and acrylates, polymers containing phthalocyanine, polyacene quinones, coordination polymers containing metal ions, conjugated-backbone polymers, and 'metallic' conducting polymers. Tables summarizing the results of SIP radiation tests (such as those performed for the NASA Galileo Project) are included.

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

1986-01-01

417

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

SciTech Connect

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

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

2011-01-01

418

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

NASA Astrophysics Data System (ADS)

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

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

419

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

420

Quantum-chemical ab initio investigation of the vibrational spectrum of halon 1113 and its anharmonic force field: A joint experimental and computational approach  

NASA Astrophysics Data System (ADS)

Halon 1113 (chlorotrifluoroethene), used in the synthesis of fluorocarbon-based polymers, has been recently detected in the atmosphere and it is a potential source of chlorine atoms. In this work, the vibrational properties of chlorotrifluoroethene are studied in the 125-5000 cm-1 region by coupling Fourier-transform infrared spectroscopy and high-level ab initio calculations. The vibrational analysis is performed over the whole spectral range and band intensities are obtained in the range 400-3100 cm-1. Ab initio calculations of the anharmonic force field are performed at the coupled cluster level of theory employing either cc-pVTZ or ANO basis sets. Vibration perturbation theory is applied to obtain spectroscopic parameters from the computed anharmonic force fields. The present results provide a solid interpretation of chlorotrifluoroethene vibrational spectrum, and they represent a significant reference for future studies on this molecule, being also the first published data on absorption cross sections and ab initio calculations.

Tasinato, Nicola; Pietropolli Charmet, Andrea; Stoppa, Paolo; Giorgianni, Santi; Gambi, Alberto

2012-03-01

421

Fluorine-free high-resolution selective plasma etching of silicon-oxide layers on silicon substrates  

NASA Astrophysics Data System (ADS)

Highly selective and vertical dry etching of SiO2 structures on silicon substrates is reported using a mixture of C2H2 and H2 gases in a direct current plasma reactor and at elevated temperatures ranging from 420 to 620 °C. Good anisotropic etching of SiO2 features can be achieved by this process without a need for fluorocarbon-based gases which are used to increase the selectivity of etching and to avoid the removal of the underlying silicon. The vertically etched patterns of SiO2 have been accomplished with a high selectivity over the Si and Si3N4 layers. The etch rate can be adjusted to obtain values between 2 and 20 nm min-1 depending on the temperature as well as the gas composition and plasma conditions.

Abdolahad, M.; Naghsh Nilchi, J.; Mohajerzadeh, S.

2010-10-01

422

The importance of the Montreal Protocol in protecting climate  

PubMed Central

The 1987 Montreal Protocol on Substances that Deplete the Ozone Layer is a landmark agreement that has successfully reduced the global production, consumption, and emissions of ozone-depleting substances (ODSs). ODSs are also greenhouse gases that contribute to the radiative forcing of climate change. Using historical ODSs emissions and scenarios of potential emissions, we show that the ODS contribution to radiative forcing most likely would have been much larger if the ODS link to stratospheric ozone depletion had not been recognized in 1974 and followed by a series of regulations. The climate protection already achieved by the Montreal Protocol alone is far larger than the reduction target of the first commitment period of the Kyoto Protocol. Additional climate benefits that are significant compared with the Kyoto Protocol reduction target could be achieved by actions under the Montreal Protocol, by managing the emissions of substitute fluorocarbon gases and/or implementing alternative gases with lower global warming potentials. PMID:17360370

Velders, Guus J. M.; Andersen, Stephen O.; Daniel, John S.; Fahey, David W.; McFarland, Mack

2007-01-01

423

The PICASSO Dark Matter Experiment  

SciTech Connect

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 [Department of Physics, Laurentian University, Sudbury, ON, P3E 2C6 (Canada); Collaboration: PICASSO Collaboration

2011-12-16

424

Two-stage optical parametric chirped-pulse amplifier using sub-nanosecond pump pulse generated by stimulated Brillouin scattering compression  

NASA Astrophysics Data System (ADS)

We demonstrate optical parametric chirped-pulse amplification (OPCPA) based on two-beam pumping, using sub-nanosecond pulses generated by stimulated Brillouin scattering compression. Seed pulse energy, duration, and center wavelength were 5 nJ, 220 ps, and ˜1065 nm, respectively. The 532 nm pulse from a Q-switched Nd:YAG laser was compressed to ˜400 ps in heavy fluorocarbon FC-40 liquid. Stacking of two time-delayed pump pulses reduced the amplifier gain fluctuation. Using a walk-off-compensated two-stage OPCPA at a pump energy of 34 mJ, a total gain of 1.6 × 105 was obtained, yielding an output energy of 0.8 mJ. The amplified chirped pulse was compressed to 97 fs.

Ogino, Jumpei; Miyamoto, Sho; Matsuyama, Takahiro; Sueda, Keiichi; Yoshida, Hidetsugu; Tsubakimoto, Koji; Miyanaga, Noriaki

2014-12-01

425

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

426

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

SciTech Connect

In this paper, we report theoretical electron impact ionization cross sections from threshold to 2000 eV for isocarbonic open chain molecules C{sub 4}H{sub 6}, C{sub 4}H{sub 8}, C{sub 4}F{sub 6} including their isomers, and closed chain molecules c-C{sub 4}H{sub 8} and c-C{sub 4}F{sub 8}. Theoretical formalism employed presently, viz., Complex Scattering Potential-ionization contribution method has been used successfully for a variety of polyatomic molecules. The present ionization calculations are very important since results available for the studied targets are either scarce or none. Our work affords comparison of C{sub 4} containing hydrocarbon versus fluorocarbon molecules. Comparisons of the present ionization cross sections are made wherever possible, and new ionization data are also presented.

Patel, Umang R., E-mail: umangpatel193@yahoo.ca [Gandhinagar Institute of Technology, Moti Bhoyan, Gandhinagar-382721, Gujarat (India); Sardar Patel University, Vallabh Vidyanagar-388120, Gujarat (India); Joshipura, K. N.; Pandya, Siddharth H. [Sardar Patel University, Vallabh Vidyanagar-388120, Gujarat (India)] [Sardar Patel University, Vallabh Vidyanagar-388120, Gujarat (India); Kothari, Harshit N. [Universal College of Engineering and Technology, Moti Bhoyan, Gandhinagar-382721, Gujarat (India)] [Universal College of Engineering and Technology, Moti Bhoyan, Gandhinagar-382721, Gujarat (India)

2014-01-28

427

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

428

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

429

Neuroprotective Effects of Perflurocarbon (Oxycyte) after Contusive Spinal Cord Injury  

PubMed Central

Abstract Spinal cord injury (SCI) often results in irreversible and permanent neurological deficits and long-term disability. Vasospasm, hemorrhage, and loss of microvessels create an ischemic environment at the site of contusive or compressive SCI and initiate the secondary injury cascades leading to progressive tissue damage and severely decreased functional outcome. Although the initial mechanical destructive events cannot be reversed, secondary injury damage occurs over several hours to weeks, a time frame during which therapeutic intervention could be achieved. One essential component of secondary injury cascade is the reduction in spinal cord blood flow with resultant decrease in oxygen delivery. Our group has recently shown that administration of fluorocarbon (Oxycyte) significantly increased parenchymal tissue oxygen levels during the usual postinjury hypoxic phase, and fluorocarbon has been shown to be effective in stroke and head injury. In the current study, we assessed the beneficial effects of Oxycyte after a moderate-to-severe contusion SCI was simulated in adult Long-Evans hooded rats. Histopathology and immunohistochemical analysis showed that the administration of 5?mL/kg of Oxycyte perfluorocarbon (60% emulsion) after SCI dramatically reduced destruction of spinal cord anatomy and resulted in a marked decrease of lesion area, less cell death, and greater white matter sparing at 7 and 42 days postinjury. Terminal deoxynucleotidyl transferase dUTP nick end labeling staining showed a significant reduced number of apoptotic cells in Oxycyte-treated animals, compared to the saline group. Collectively, these results demonstrate the potential neuroprotective effect of Oxycyte treatment after SCI, and its beneficial effects may be, in part, a result of reducing apoptotic cell death and tissue sparing. Further studies to determine the most efficacious Oxycyte dose and its mechanisms of protection are warranted. PMID:24025081

Yacoub, Adly; Hajec, Marygrace C.; Stanger, Richard; Wan, Wen; Young, Harold

2014-01-01

430

Electron attachment mass spectrometry as a diagnostics for electronegative gases and plasmas  

NASA Astrophysics Data System (ADS)

Electron attachment mass spectrometry (EAMS) has been developed to study mixtures of electronegative gases and plasmas. A quadrupole mass spectrometer (QMS) has been used to detect negative ions, formed from sampled species by attachment of low energy electrons. Varying the electron energy allows to collect the attachment cross section of the considered species. EAMS appears to be a very powerful technique to study the chemistry of electronegative gases. Unlike ionization mass spectrometry, where cross sections are low at the threshold and rather flat over a broad range of electron energies, attachment resonances are sharp and distinct. Also very limited fragmentation of the parent negative ion occurs, so a given molecule yields only a few different negative ions. This facilitates identification of components in a gas mixture. It is particularly advantageous for detection of large, fragile molecules, which break up after ionization, but can be easily transformed into large negative ions. Moreover, sensitive detection of active species is possible due to their relatively high attachment cross sections. A particularly important application of EAMS is the determination of an effective attachment cross section in a plasma. Recording this cross section allows to decide on the actual negative ion formation mechanism in the plasma environment, where active products of plasma conversion can significantly alter the negative ion production channels and consequently the whole balance of charged particles. Examples of EAMS applications to fluorocarbon gases and low-pressure radio-frequency plasmas are discussed. In a CF4 discharge conversion of the parent gas into species like C2F6 and C3F8 is easily visualized. The dominant mechanism of negative ion formation in the plasma is electron attachment to these minority species and not to the parent gas. Also larger polymers are readily formed in fluorocarbon plasmas. In a C2F6 discharge molecules with up to ten carbon atoms (the mass limit of our apparatus) have been detected using EAMS.

Stoffels, E.; Stoffels, W. W.; Tachibana, K.

1998-01-01

431

Role of acentric displacements on the crystal structure and second-harmonic generating properties of RbPbCO3F and CsPbCO3F.  

PubMed

Two lead fluorocarbonates, RbPbCO3F and CsPbCO3F, were synthesized and characterized. The materials were synthesized through solvothermal and conventional solid-state techniques. RbPbCO3F and CsPbCO3F were structurally characterized by single-crystal X-ray diffraction and exhibit three-dimensional (3D) crystal structures consisting of corner-shared PbO6F2 polyhedra. For RbPbCO3F, infrared and ultraviolet-visible spectroscopy and thermogravimetric and differential thermal analysis measurements were performed. RbPbCO3F is a new noncentrosymmetric material and crystallizes in the achiral and nonpolar space group P6m2 (crystal class 6m2). Powder second-harmonic generation (SHG) measurements on RbPbCO3F and CsPbCO3F using 1064 nm radiation revealed an SHG efficiency of approximately 250 and 300 × ?-SiO2, respectively. Charge constants d33 of approximately 72 and 94 pm/V were obtained for RbPbCO3F and CsPbCO3F, respectively, through converse piezoelectric measurements. Electronic structure calculations indicate that the nonlinear optical response originates from the distorted PbO6F2 polyhedra, because of the even-odd parity mixing of the O 2p states with the nearly spherically symmetric 6s electrons of Pb(2+). The degree of inversion symmetry breaking is quantified using a mode-polarization vector analysis and is correlated with cation size mismatch, from which it is possible to deduce the acentric properties of 3D alkali-metal fluorocarbonates. PMID:24867361

Tran, T Thao; Halasyamani, P Shiv; Rondinelli, James M

2014-06-16

432

Controlling modulus and morphology of hydrogel tubes through surface modification.  

PubMed

Crosslinked, porous poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) (PHEMA-MMA) tubes were prepared in cylindrical glass molds using a new centrifugal casting process developed in our group. The resulting hydrogel tubes have a bi-phasic wall structure, with a spongy inner layer and a gel-like outer layer, the latter of which provides mechanical strength to the tube. While many factors influence wall morphology and, thus, mechanical properties, we focused on the effect of the surface properties of the glass mold in which tubes are synthesized. Specifically, we investigated the impact of a diverse set of silane modifications of the glass mold on tube morphology, elastic modulus and mold release. We treated activated glass surfaces with one of three alkoxysilanes having either ethoxy, amine or fluorocarbon end-groups. Silane-modified glass surfaces were found to be more hydrophobic than the unmodified glass mold, with the most hydrophobic surface being that of the fluorocarbon-terminated silane. The presence of the silane layer on the mold was confirmed by X-ray photoelectron spectroscopy and the stability of this modification was confirmed by examining the surface chemistry of the hydrogel tubes. The biphasic hydrogel tube wall structure was observed for all tubes, yet those tubes synthesized in unmodified molds had a cracked outer morphology, whereas those synthesized in silane-modified molds had a smooth outer morphology. This influenced the mechanical properties of the tubes where tubes synthesized in silane-modified molds had a significantly greater elastic modulus than those tubes synthesized in unmodified molds. Release from the molds was easiest with ethoxy- and amine-functionalized silane mold modifications. PMID:15109099

Enescu, Cristina; Shoichet, Molly S

2004-01-01

433

Damage by radicals and photons during plasma cleaning of porous low-k SiOCH. I. Ar/O{sub 2} and He/H{sub 2} plasmas  

SciTech Connect

Porous dielectric materials offer lower capacitances that reduce RC time delays in integrated circuits. Typical porous low dielectric (low-k) materials include SiOCH-silicon dioxide with carbon groups, principally -CH{sub 3}, lining the pores. Fluorocarbon plasmas are often used to etch such low-k materials. These processes leave a fluorocarbon polymer on the SiOCH surface that must be removed, often with oxygen or hydrogen containing plasmas. Pores open to the surface and that are internally connected provide pathways for reactive species to enter into the porous network and produce damage. For example, during cleaning using O{sub 2} containing plasmas, reactions of O atoms with -CH{sub 3} groups can increase the k-value by removing C atoms. Vacuum ultraviolet (VUV) photons produced by the plasma and that penetrate into the material can scission -Si-CH{sub 3} bonds and accelerate the removal of -CH{sub 3} groups. This paper reports on results from a computational investigation of Ar/O{sub 2} and He/H{sub 2} plasma cleaning of porous SiOCH when including the effects of VUV photons. The authors found that He/H{sub 2} plasmas are able to clean CF{sub x} polymers deposited during etching while producing milder damage to underlying -CH{sub 3} sites compared to O{sub 2} plasmas due to the lower reactivity of H atoms and the shorter penetration distance of photons produced in He/H{sub 2} plasmas.

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

2012-07-15

434

TEWI Analysis: Its Utility, Its Shortcomings, and Its Results  

SciTech Connect

The past decade has been a challenging time for the refrigeration and air conditioning industry worldwide. Provisions of the Montreal Protocol and its amendments require the phaseout of chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) compounds that have been used extensively as insulating foam blowing agents and refrigerants in refrigeration systems, heat pumps, and air conditioners. In response, hydrofluorocarbon (HFC) compounds were proposed, developed, and are starting to be used as the primary alternatives to CFCs and HCFCs. However, in 1997 under the Kyoto Protocol, industrialized nations have agreed to roll back emissions of HCFCs, carbon dioxide (CO*), and four other greenhouse gases which threaten to cause excessive global warming. The US. Department of Energy and the Alternative Fluorocarbon Environmental Acceptability Study (AFEAS) jointly sponsored research projects to identify the major applications of CFCs, HCFCs, and HFCs and to examine the impacts of these compounds and the energy use of applications employing these compounds on global warming. The five major uses of fluorocarbons based on sales were automobile air conditioning, supermarket refrigeration, unitary heat pumps and air conditioning, chillers for cooling large office buildings, and household refrigeration. Almost all of the refrigerants used in these applications are global warming gases, and if the refrigerant leaks out of the system during operation, is lost during maintenance or is not recovered when the system is scraped, it contributes to global warming. But, it is also true that the energy consumed by refrigeration and air conditioning systems, in the form of electricity or the direct combustion of fossil fuel, results in the release of CO*, the primary cause of atmospheric global warming.

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

1999-09-13

435

Composite propellant aluminum agglomeration reduction using tailored Al/PTFE particles  

NASA Astrophysics Data System (ADS)

Micron aluminum is widely used in propellants; however, performance could be significantly improved if ignition barriers could be disrupted and combustion tailored. In solid propellants for example, aluminum increases theoretical specific impulse performance, yet theoretical levels cannot be achieved largely because of two-phase flow losses. These losses could be reduced if particles quickly ignited, more gaseous products were produced, and if particle breakup occurred during combustion. To achieve altered aluminum ignition and particle combustion, this work explores the use of low level (10-30 wt.%) fluorocarbon (polytetrafluoroethylene (PTFE) or poly(carbon monofluoride) (PMF)) inclusion inside of aluminum via low or high energy mechanical activation. Aluminum/PTFE particles are found to be amenable to use in binder based energetics, having average particle sizes ranging from 15 to 78 ?m, ~2-7 m2/g, specific surface area, and combustion enthalpies as high as 20.2 kJ/g. Differential scanning calorimetry (DSC) experiments indicate high energy MA reduces both reaction and oxidation onset to ~440 °C that is far below aluminum alone. Safety testing shows these particles have high electrostatic discharge (ESD) (89.9-108 mJ), impact (> 213 cm), and friction (> 360 N) ignition thresholds. The idea of further increasing reactivity and increasing particle combustion enthalpy is explored by reducing fluorocarbon inclusion content to 10 wt.% and through the use of the strained fluorocarbon PMF. Combustion enthalpy and average particle size range from 18.9 to 28.5 kJ/g and 23.0 to 67.5 ?m, respectively and depend on MA intensity, duration, and inclusion level. Specific surface areas are high (5.3 to 34.8 m2/g) and as such, Al/PMF particles are appropriate for energetic applications not requiring a curable liquid binder. Mechanical activation reduces oxidation onset (DSC) from 555 to 480 °C (70/30 wt.%). Aluminum/PMF particles are sensitive to ESD (11.5-47.5 mJ) and some can be ignited via optical flash. Propellant aluminum agglomeration is assessed through replacement of reference aluminum powders (spherical, flake, or nanoscale) with Al/PTFE (90/10 or 70/30 wt.%) particles. The effects on burning rate, pressure dependence, and aluminum ignition, combustion, and agglomeration are quantified. Microscopic imaging shows tailored particles promptly ignite at the burning surface and appear to breakup into smaller particles. Replacement of spherical aluminum with Al/PTFE 70/30 wt.% also increases the pressure exponent from 0.36 to 0.58, which results in a 50% increase in propellant burning rate at 13.8 MPa. Combustion products were quench collected using a liquid-free technique at 2.1 and 6.9 MPa. Sizing of products indicates that composite particles result in nominally 25 ?m coarse products, which are smaller than the original, average particle size and are also 66% smaller in diameter (96% by volume) than the 76 ?m products collected from reference spherical aluminized propellant. Smaller diameter condensed phase products and more gaseous products will likely decrease two-phase flow loss and reduce slag accumulation in solid rocket motors.

Sippel, Travis R.

436

Diagnostic studies and modeling of inductively coupled plasmas  

NASA Astrophysics Data System (ADS)

The focus of this dissertation is the study of plasma-surface interactions and plasma chemistries through experimental approaches and numerical simulation. Various diagnostic studies and modeling of inductively coupled plasmas are described. Ruthenium etching with O2- and Cl2-containing ICP is studied. Ru etches readily in O2-containing plasmas. With Cl 2 addition, our observations include a significant increase in the etching rate, the detection of RuO4 at the downstream, the detection of RuOxCly ions in the plasma, and virtually zero wall deposition. Both O- and Cl-containing species (ions and/or neutrals) are necessary to explain the Cl2-addition effects. Diagnostic studies of Ar and octafluorocyclobutane plasmas are performed. The plasma species, the wall deposition rate, and the downstream species are quantified. Ar and F are the dominant radicals while CF+ and Ar+ appear to be the dominant ions. The detection of larger fluorocarbon ion species suggests the existence of larger fluorocarbon neutrals. The material balance shows over 30% of the incoming F- and C-containing species deposit on the chamber wall. Two OnWafer commercial plasma sensor systems are tested in the ICP system. Measurements of wafer temperature transients (using PlasmaTeMP(TM)) are compared to an energy transport model. Model predictions and measurements of transient wafer temperature profiles agree near-quantitatively, if details of the plasma heating sources and wafer characteristics are properly included. We outline a procedure to relate the temperature measurements to the surface ion flux profile. Measurements of the RF-current at the wafer surface (using PlasmaVolt(TM)) are shown to be approximately proportional to the square root of the electron density at the sheath edge. Comparisons of fluid model predictions with measurements in the ICP are reported. The model couples neutral flow, plasma, and electromagnetic equations. The gas chemistries used include Ar, Ar/O2, and Ar/O 2/Cl2. Measurements of electron density, EEPF, positive ion flux and its composition, and radical density at the wall are compared to corresponding model predictions. Radical and ion composition predictions are in good agreement for Ar and Ar/O2 plasmas, but the corresponding predictions in Ar/O2/Cl2 plasmas are in only partial agreement with measurements, implying that the chemical reaction database for this chemistry requires further work.

Hsu, Cheng-Che

437

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

438

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

439

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

440

Plasma-surface interactions of model polymers for advanced photoresist systems  

NASA Astrophysics Data System (ADS)

Plasma processing of advanced photoresist (PR) materials is a critical step in nano-manufacturing. We have studied the interactions of PRs and polymers in fluorocarbon/Ar discharges. The effects of process time, PR material, bias and source power, pressure and gas chemistry (C4F8/Ar, CF4/Ar and CF4/H2/Ar) were studied by ellipsometry, atomic force microscopy and x-ray photoelectron spectroscopy. Additionally, patterned structures of 193nm PR were examined using scanning electron microscopy. Polymer destruction in the top surface, oxygen and hydrogen loss along with fluorination were observed for all materials initially, which was followed by steady state etch conditions. A strong dependence of plasma-induced surface chemical and morphological changes on polymer structure was observed. In particular, the adamantane group of 193 nm PR showed poor stability. Two linked mechanisms for the roughening behavior of the films during processing were identified: A physical pattern transfer mechanism enhances initial roughness by nonuniform removal. Additional to that, roughness formation occurred linear to the energy density deposited during processing. For adamantyl polymers, a higher roughening constant was found. Additionally, fluorocarbon (FC) deposition on the damaged PR affected roughening in two opposing ways: Ion-induced mixing with the damaged PR increased roughening, whereas for simple FC precursor deposition a reduction of roughness was seen. Fluorination of the PR surfaces using plasma increased etching yields, which were found to improve the roughness of 193nm PR after etch. The fluorination of the PR prevented the formation of characteristic small scale roughness features at the cost of large scale roughness introduction. Use of low energy density processes suppressed the roughness growth by ion-induced transfer. Examining 3-dimensional trenches and contact holes patterned in PR showed that the sidewall roughness changed with process parameters similar to that seen for blanket films. The close correlation suggested that our model of polymer surface roughening also applies to resist sidewall evolution during etch. All process conditions can be combined in the energy density roughening model. Even for various feedgas chemistries adamantyl containing polymers show enhanced roughening rates, suggesting that the instability of the adamantyl structure used in 193nm PR polymers is the performance limiting factor for processing PR materials.

Engelmann, Sebastian Ulrich

441

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.

442

Radiation transport in low pressure plasmas: Lighting and semiconductor etching plasmas  

NASA Astrophysics Data System (ADS)

In some technological plasmas like lamps, the transport of UV radiation is an important design consideration. In other instances, such as semiconductor materials processing, the role of UV photons in surface processes is poorly understood. Since the basic surface reaction mechanisms in semiconductor processing are now being developed, it is an opportune time to investigate the role of UV photons. To investigate radiative processes in lighting plasmas, a Monte Carlo Radiation Transport Model was developed and interfaced with a two-dimensional plasma equipment model (HPEM). Investigations were performed on low pressure Ar/Hg electrodeless discharges. We found that analytically computed radiation trapping factors are less accurate when there is a non-uniform density of absorbers and emitters, as may occur in low pressure lamps. In our case these non-uniformities are due primarily to cataphoresis. We found that the shape of the plasma cavity influences trapping factors, primarily due to the consequences of transport of Hg ions on the distribution of radiators. To address the role of radiation transport in semiconductor etching plasmas, we investigated the plasma etching of SiO2 in fluorocarbon plasmas, a process dependent on polymer deposition. We first developed a surface reaction mechanism to understand the role played by the polymer film that overlays the SiO2 substrate, and is essential to facilitating an etch. This mechanism was implemented in a Surface Kinetics Model of the HPEM. We found that the dominant etch channel in C4F8 plasmas was due to the fluorine released in the polymer layer by energetic ion bombardment. For plasmas that do not lead to strongly bound films (like C2F 6 plasmas), defluorination is no longer the dominant SiO2 etch process. Finally, we combined the models above to address radiation transport in fluorocarbon/Ar etching plasmas. We found that resonance radiation from Ar produced only small increases in etch rate due to photon-induced defluorination, and this increase was well offset by the decrease in etch rate due to a lower amount of etchant fluorine in the polymer layer. At the process regimes of interest to us, the ion-induced defluorination was much more dominant than UV-induced defluorination.

Rajaraman, Kapil

443

Efficient, environmentally acceptable method for waterproofing insulation material  

NASA Technical Reports Server (NTRS)

A process of waterproofing alumina-rich or silica-rich fibrous thermal insulation material, the process including the steps of: (a) providing an alumina-rich or a silica-rich fibrous material; (b) providing a waterproofing solution including: (1) a carrier solvent selected from the group consisting of aliphatic alcohols having from 1C to 6C, water, and mixtures thereof; and (2) an alkoxysilane defined by the formula R.sub.4-x -Si-(O-R').sub.x where x is 1-3 and R is selected from the group consisting of alkyl groups having from 1C to 10C, hydrogen, or fluorocarbon groups having from 1F to 15F; and where O-R' is an alkoxy group having from 1C to 5C, or a mixture of alkoxysilanes defined by the above formula R.sub.4-x -Si-(O-R').sub.x ; and optionally (3) modifiers including acids, such as acetic acid or nitric acid, or bases, such as ammonium hydroxide, RNH.sub.2, R.sub.2 NH, or R.sub.3 N, or MOH, where R is selected from the group consisting of alkyl groups having from 1C to 10C or hydrogen, and where M=Na, Li, or K; (c) contacting the fibrous material with the waterproofing solution for a sufficient amount of time to waterproof the fibrous material; and (d) curing the coated fibrous material to render it sufficiently waterproof. A chemical solution for waterproofing alumina-rich or silica-rich fibrous thermal insulation materials, the solution including: (a) a carrier solvent selected from the group consisting of aliphatic alcohols having from 1C to 6C, water, and mixtures thereof; and (b) an alkoxysilane defined by the formula R.sub.4-x -Si-(O-R').sub.x where x is 1-3 and R is selected from the group consisting of alkyl groups having from 1C to 10C, hydrogen, or fluorocarbon groups having from 1F to 15F; and where O-R' is an alkoxy group having from 1C to 5C, or a mixture of alkoxysilanes defined by the above formula R.sub.4-x -Si-(O-R').sub.x ; and optionally (c) modifiers including acids, such as acetic acid or nitric acid, or bases, such as ammonium hydroxide, RNH.sub.2, R.sub.2 NH, or R.sub.3 N, or MOH, where R is selected from the group consisting of alkyl groups having from 1C to 10C or hydrogen, and where M=Na, Li, or K.

Blohowiak, Kay Y. (Inventor); Krienke, Kenneth A. (Inventor); Olli, Larry K. (Inventor); Newquist, Charles W. (Inventor)

2000-01-01

444

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

445

Nuclear criticality safety assessment of the proposed CFC replacement coolants  

SciTech Connect

The neutron multiplication characteristics of refrigerant-114 (R-114) and proposed replacement coolants perfluorobutane (C{sub 4}F{sub 10}) and cycloperfluorobutane C{sub 4}F{sub 8}) have been compared by evaluating the infinite media multiplication factors of UF{sub 6}/H/coolant systems and by replacement calculations considering a 10-MW freezer/sublimer. The results of these comparisons demonstrate that R-114 is a neutron absorber, due to its chlorine content, and that the alternative fluorocarbon coolants are neutron moderators. Estimates of critical spherical geometries considering mixtures of UF{sub 6}/HF/C{sub 4}F{sub 10} indicate that the flourocarbon-moderated systems are large compared with water-moderated systems. The freezer/sublimer calculations indicate that the alternative coolants are more reactive than R-114, but that the reactivity remains significantly below the condition of water in the tubes, which was a limiting condition. Based on these results, the alternative coolants appear to be acceptable; however, several follow-up tasks have been recommended, and additional evaluation will be required on an individual equipment basis.

Jordan, W.C.; Dyer, H.R.

1993-12-01

446

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

447

Cardiac arrhythmias and blood levels associated with inhalation of Halon 1301.  

PubMed

In this study we determined airborne concentrations of Halon 1301 (CBrF3) and the associated blood levels which produce cardiac arrhythmias in dogs. Beagle dogs were exposed by inhalation to Halon 1301 concentrations ranging from 5 to 20% and, after five minutes of exposure, were given epinephrine by intravenous injection (8--10 micrograms/kg). Electrocardiograms were recorded. Serious cardiac arrhythmias were produced with concentrations of 7.5% or greater. A second group of dogs with cannulas surgically implanted in the common carotid artery and external jugular vein were exposed to 5%, 7.5% and 10% Halon 1301 for 60 minutes. The blood concentration of Halon 1301 increased rapidly during the first five minutes of exposure, plateaued within twenty minutes, and declined rapidly after exposure. The mean blood concentrations at equilibrium were directly proportional to airborne concentrations: at a concentration of 5% in air -- arterial 19.2 micrograms/mL, venous 14.6 micrograms/mL; at 7.5% in air -- arterial 30.6 micrograms/mL, venous 28.4 micrograms/mL; and at 10% in air -- arterial 402 micrograms/mL, venous 32.1 microgram/mL. Since there was no rapid increase in blood fluorocarbon concentration after the first five minutes of exposure, it does not seem likely that risk of cardiac sensitization would increase with increased length of exposure to a given concentration. PMID:484490

Mullin, L S; Reinhardt, C F; Hemingway, R E

1979-07-01

448

Structural basis for the enhanced stability of highly fluorinated proteins  

PubMed Central

Noncanonical amino acids have proved extremely useful for modifying the properties of proteins. Among them, extensively fluorinated (fluorous) amino acids seem particularly effective in increasing protein stability; however, in the absence of structural data, the basis of this stabilizing effect remains poorly understood. To address this problem, we solved X-ray structures for three small proteins with hydrophobic cores that are packed with either fluorocarbon or hydrocarbon side chains and compared their stabilities. Although larger, the fluorinated residues are accommodated within the protein with minimal structural perturbation, because they closely match the shape of the hydrocarbon side chains that they replace. Thus, stability increases seem to be better explained by increases in buried hydrophobic surface area that accompany fluorination than by specific fluorous interactions between fluorinated side chains. This finding is illustrated by the design of a highly fluorinated protein that, by compensating for the larger volume and surface area of the fluorinated side chains, exhibits similar stability to its nonfluorinated counterpart. These structure-based observations should inform efforts to rationally modulate protein function using noncanonical amino acids. PMID:22411812

Buer, Benjamin C.; Meagher, Jennifer L.; Stuckey, Jeanne A.; Marsh, E. Neil G.

2012-01-01

449

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

450

Investigations of the etching chemistry of electronic materials  

NASA Astrophysics Data System (ADS)

The production of VLSI devices involves the fabrication of silicon substrates with micron-scale anisotropic features incorporating a number of distinct materials, such as silicon regions of various electrical properties, grown or deposited insulating layers, and metallizations. Currently, a variety of plasma-based processes are used to achieve the requisite level of profile control. A common feature of these methods is that the reaction is effected by radical and ionic species in a fluorocarbon plasma. In order to begin to investigate some of the mechanisms involved in etching reactions, a series of experiments has been conducted probing the interaction between fluorine atoms (supplied by the dissociative chemisorption of XeF2) and the surfaces of silicon. The experiments were performed by exposing the clean substrates, either (111) wafers or ingots for cleaving, to XeF2 in a special dosing chamber. The samples were then transferred into the spectrometer chamber through a double vacuum lock after pumping away the residual XeF2. High resolution core level spectra were obtained by means of a two-dimensional display type photoemission spectrometer operating in conjunction with a three-meter toroidal grating monochromator situated at beam line UV-8 at NSLS.

McFeely, F. R.; Morar, J. F.; Himpsel, F. J.

451

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

452

Optical nonlinearities in As2Se3 chalcogenide glasses doped with Cu and Ag for pulse durations on the order of nanoseconds.  

PubMed

We investigate the dependence of the nonlinear optical properties of Cu-doped and Ag-doped As(2)Se(3) glasses on the incident pulse-width at 1.064 microm using the Z-scan technique. In this work, 11.5-ns optical pulses from a Nd:YAG laser were compressed up to 1.6 ns by using stimulated Brillouin scattering in heavy fluorocarbon liquid. The measurement of the pulse-width dependence of the optical nonlinearities leads to the separation of an ultrafast Kerr nonlinearity and a slow (cumulative) nonlinearity such as a thermal nonlinearity. The measured values of the nonlinear refractive index and the nonlinear absorption coefficient of 4 at.% Cu-doped As(2)Se(3) glass (where the normal photodarkening effect is sufficiently suppressed) and 4 at.% Ag-doped As(2)Se(3) glass were proportional to the pulse width, showing that the cumulative nonlinearity is present in these two glasses. The cumulative nonlinearity of these doped glasses is larger than one of the undoped glass. The origin of such slow nonlinearity is presumably attributed to the photostructural changes inherent in chalcogenide glasses and is directly independent of one of photodarkening. PMID:19434148

Ogusu, Kazuhiko; Shinkawa, Kenta

2009-05-11

453

Pulse-width dependence of optical nonlinearities in As2Se3 chalcogenide glass in the picosecond-to-nanosecond region.  

PubMed

We study the dependence of optical nonlinearities in As(2)Se(3) glass on the incident pulse-width using the Z-scan technique. In this work, 11.5-ns optical pulses from a Nd:YAG laser operating at 1.064 mum were compressed up to 1.6 ns by using stimulated Brillouin scattering in heavy fluorocarbon liquid, where the duration of the compressed pulses depends on the pump energy. Moreover picosecond optical pulses with a 1.053-mum wavelength were utilized for the Z-scan experiments. To investigate the pulse-width dependence of the optical nonlinearities leads to the separation of an ultrafast Kerr nonlinearity and a slow (cumulative) nonlinearity such as a thermal nonlinearity because the magnitude of the cumulative nonlinearity should be proportional to the pulse duration. The experimental results clearly show that both the nonlinear refractive index and the nonlinear absorption coefficient increase linearly with pulse width. The origin of such pulse-width dependence is presumably attributed to photostructural changes inherent in chalcogenide glasses, which are induced not by nonlinear absorption such as two-photon absorption or two-step absorption, but by linear absorption in the weak-absorption region. PMID:18958100

Shinkawa, Kenta; Ogusu, Kazuhiko

2008-10-27

454

Design of dissolution inhibitors for chemically amplified photolithographic systems  

NASA Astrophysics Data System (ADS)

Current semiconductor manufacturing utilizes exposure wavelengths from 365 nm to 193 nm, and current research is centered on photoresist development for 157 nm. Our research group discovered the strong inhibition response in the fluorocarbon resins designed for use at 157 nm. We have been investigating dissolution inhibitors (DIs), some of which also serve as photoacid generators (PAGs), that strongly inhibit the dissolution of poly(2-(3,3,3-trifluoro-2-trifuoromethyl-2-hydroxypropyl) bicyclo[2.2.1]heptane-5-ene)(PNBHFA) (1) and the Asahi glass RS001 polymer (2). These inhibiting PAGs, in particular, result in the creation of 2-component resist systems consisting only of the resin polymer and the PAG-DI. This design enables greater ease of formulation, reduces the number of variables present in resist development, and offers improvements in sensitivity and line edge roughness. The synthetic approach has been to design transparent, inhibiting compounds for use at 157 nm. However, during our investigation of these compounds, we found that there is an inherent "backwards compatibility" for these PAGs and DIs at 193 nm, 248 nm and 365 nm. This has created the ability to effectively design dissolution inhibitors, photoactive or otherwise, that span virtually all of the wavelengths used in photolithographic processes today. Here we will present the design, development and imaging of modern dissolution inhibitors suitable for use in a wide range of photolithography technologies.

Chambers, Charles R.; Kusumoto, Shiro; Osborn, Brian P.; Vasudev, Alok; Ootani, Michitaka; Walthal, Leonidas; McMichael, Hale; Zimmerman, Paul A.; Conley, Willard E.; Willson, C. Grant

2004-05-01

455

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

456

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

457

Injection molding of high aspect ratio sub-100 nm nanostructures  

NASA Astrophysics Data System (ADS)

We have explored the use of mold coatings and optimized processing conditions to injection mold high aspect ratio nanostructures (height-to-width >1) in cyclic olefin copolymer (COC). Optimizing the molding parameters on uncoated nickel molds resulted in slight improvements in replication quality as described by height, width and uniformity of the nanoscopic features. Use of a mold temperature transiently above the polymer glass transition temperature (Tg) was the most important factor in increasing the replication fidelity. Surface coating of the nickel molds with a fluorocarbon-containing thin film (FDTS) greatly enhanced the quality of replicated features, in particular at transient mold temperatures above Tg. Injection molding using the latter mold temperature regime resulted in a bimodal distribution of pillar heights, corresponding to either full or very poor replication of the individual pillars. The poorly replicated structures on nickel molds with or without FDTS coatings all appeared fractured. We investigated the underlying mechanism in a macroscopic model system and found reduced wetting and strongly decreased adhesion of solidified COC droplets on nickel surfaces after coating with FDTS. Reduced adhesion forces are consistent with lowered friction that reduces the risk of fracturing the nanoscopic pillars during demolding. Optimized mold surface chemistry and associated injection molding conditions permitted the fabrication of square arrays of 40 nm wide and 107 nm high (aspect ratio >2.5) pillars on a 200 nm pitch.

Matschuk, Maria; Larsen, Niels B.

2013-02-01

458

Cask systems development program seal technology  

SciTech Connect

General design or test performance requirements for radioactive materials (RAM) packages are specified in Title 10 of the US Code of Federal Regulations Part 71 (10 CFR 71). Seals that provide the containment system interface between the packaging body and the closure must function in both high- and low-temperature environments under dynamic and static conditions. Experiments were performed to characterize the performance of several seal materials at low temperatures. Helium leak tests on face seals were used to compare the materials. Materials tested include butyl, neoprene, ethylene propylene, fuorosilicone, silicone, Eypel, Kalrez, Teflon, fluorocarbon, and Teflon/silicone composites. Results show that the seal materials tested, with the exception of silicone S613-60, are not leak tight at manufacturer low-temperature ratings. This paper documents the initial series of experiments developed to characterize the performance of several static seals under conditions representative of RAM transport container environments. Helium leak rates of face seals were measured at low and ambient temperatures to compare seal materials. As scaling laws have not been developed for seals, the leakage rates measured in this program are intended to be used in a qualitative rather than quantitative manner. 5 refs., 7 figs., 2 tabs.

Madsen, M.M.; Edwards, K.R.; Humphreys, D.L.

1991-01-01

459

Radioactive material package seal tests  

SciTech Connect

General design or test performance requirements for radioactive materials (RAM) packages are specified in Title 10 of the US Code of Federal Regulations Part 71 (US Nuclear Regulatory Commission, 1983). The requirements for Type B packages provide a broad range of environments under which the system must contain the RAM without posing a threat to health or property. Seals that provide the containment system interface between the packaging body and the closure must function in both high- and low-temperature environments under dynamic and static conditions. A seal technology program, jointly funded by the US Department of Energy Office of Environmental Restoration and Waste Management (EM) and the Office of Civilian Radioactive Waste Management (OCRWM), was initiated at Sandia National Laboratories. Experiments were performed in this program to characterize the behavior of several static seal materials at low temperatures. Helium leak tests on face seals were used to compare the materials. Materials tested include butyl, neoprene, ethylene propylene, fluorosilicone, silicone, Eypel, Kalrez, Teflon, fluorocarbon, and Teflon/silicone composites. Because most elastomer O-ring applications are for hydraulic systems, manufacturer low-temperature ratings are based on methods that simulate this use. The seal materials tested in this program with a fixture similar to a RAM cask closure, with the exception of silicone S613-60, are not leak tight (1.0 {times} 10{sup {minus}7} std cm{sup 3}/s) at manufacturer low-temperature ratings. 8 refs., 3 figs., 1 tab.

Madsen, M.M.; Humphreys, D.L.; Edwards, K.R.

1990-01-01

460

Quantitatively controlled nanoliter liquid manipulation using hydrophobic valving and control of surface wettability  

NASA Astrophysics Data System (ADS)

In this paper, we discuss nanoliter metering, transportation, merging, and biochemical reaction on a nanoliter fluidic chip. The proposed nanoliter fluidic handling is based on passive fluidic control using hydrophobic valving and liquid flow control by selective wettability patterning. For the selective patterning of the wettability, a hydrophobic fluorocarbon (FC) film (a mixture of FluoradTM from 3M, USA) was spin-coated on a hydrophilic glass wafer and patterned using a lift-off process. The patterned FC film showed strong hydrophobicity, indicated by a high water contact angle (108-110°). For the fabrication of the nanoliter fluidic chip, polydimethysiloxane microchannel networks were aligned and bonded onto the glass wafer, along with the FC patterns. The proposed nanoliter metering technique showed an accuracy of 4% using a 20 nL criterion. A biochemical reaction on a chip was performed between beta-galactosiadase (enzyme) and a fluorescein di-beta-galactopyranoside (FDG) substrate. The FDG and the enzyme solution were manipulated on the nanoliter fluidic chip in desired volumes and mixing ratios. The reactions between different ratios of the enzyme and FDG substrate were monitored using the fluorescence intensity as a function of the reaction time. From the enzymatic reaction on the chip, we confirmed that the proposed fluidic handling was successfully performed on the chip, and that the reaction depended on the enzyme concentration.

Lee, Sang-Ho; Lee, Chang-Soo; Kim, Byung-Gee; Kim, Yong-Kweon

2003-01-01

461

Quantum cascade laser based monitoring of CF2 radical concentration as a diagnostic tool of dielectric etching plasma processes  

NASA Astrophysics Data System (ADS)

Dielectric etching plasma processes for modern interlevel dielectrics become more and more complex by the introduction of new ultra low-k dielectrics. One challenge is the minimization of sidewall damage, while etching ultra low-k porous SiCOH by fluorocarbon plasmas. The optimization of this process requires a deeper understanding of the concentration of the CF2 radical, which acts as precursor in the polymerization of the etch sample surfaces. In an industrial dielectric etching plasma reactor, the CF2 radical was measured in situ using a continuous wave quantum cascade laser (cw-QCL) around 1106.2 cm-1. We measured Doppler-resolved ro-vibrational absorption lines and determined absolute densities using transitions in the ?3 fundamental band of CF2 with the aid of an improved simulation of the line strengths. We found that the CF2 radical concentration during the etching plasma process directly correlates to the layer structure of the etched wafer. Hence, this correlation can serve as a diagnostic tool of dielectric etching plasma processes. Applying QCL based absorption spectroscopy opens up the way for advanced process monitoring and etching controlling in semiconductor manufacturing.

Hübner, M.; Lang, N.; Zimmermann, S.; Schulz, S. E.; Buchholtz, W.; Röpcke, J.; van Helden, J. H.

2015-01-01

462

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

463

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

464

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

465

Langmuir Probe Measurements of Inductively Coupled Plasmas in CF_4/Ar/O2 mixtures  

NASA Astrophysics Data System (ADS)

Fluorocarbon gases, such as CF_4, 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 (n_e), electron temperature (T_e), electron energy distribution function (EEDF), mean electron energy (E_e), ion number density (n_i), and plasma potential (V_p). In this paper we report probe data for planar inductively coupled plasmas in CF_4/O_2/Ar mixtures. By varying the relative concentrations in the mixture, radial profiles of n_e, n_i, T_e, E_e, V_p, 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.

2000-10-01

466

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. PMID:25370378

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

2014-01-01

467

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

468

Assignments of normally unoccupied orbitals to the temporary negative ion states of several lanthanide NMR shift reagents and comments on resonance involvement in electron circular dichroism.  

PubMed

We have measured the total electron scattering cross sections of several NMR shift reagent molecules X(hfc)3, where X = Yb, Er, Eu and Pr, by means of electron transmission spectroscopy (ETS) to determine their vertical attachment energies. A strong low-energy resonance (<1 eV) is observed in all of the compounds except for Yb(hfc)3. We explain this anomaly in terms of the ground-state electron configuration of each molecule. Also, with the aid of restricted open-shell Hartree-Fock (ROHF) calculations on analogous molecules with truncated fluorocarbon chains, we have assigned specific normally unoccupied orbitals to the resonances observed in ETS. To our knowledge, these molecules are the largest for which this procedure has been successfully completed. Nolting et al. (J. Phys. B 1997, 30, 5491) have demonstrated that the above NMR shift reagents exhibit electron circular dichroism (ECD) between 1 and 10 eV. Using our new total cross section data, we comment on the possibility of resonance involvement in the generation of ECD. PMID:18370426

Scheer, A M; Gallup, G A; Gay, T J

2008-05-01

469

Development of an all-metal thick film cost effective metallization system for solar cells. Interim report, May 1980-August 1981  

SciTech Connect

Copper pastes were prepared. Properties of these pastes did not reproduce earlier results in rheology and metallurgy. Electrodes made with pastes produced under the previous contract were analyzed and compared with the raw materials. A needle-like structure was observed on the earlier electroded solar cells, and was identified as eutectic copper-silicon by electron probe x ray spectroscopy. The existence of this phase was thought to benefit electrical and metallurgical properties of the contact. Subsequently electrodes made from new material were also shown to contain this phase while simultaneously having poor adhesion. A solar cell experiment including front contact experimentation was done. No electrical information was obtained due to inadequate contact adhesion. Experiments were conducted with variations in paste parameters, firing conditions, including gas ambients, furnace furniture, silicon surface and others. Semiconductor and solar cell research activities in Munich were visited and activities of mutual interest were discussed. A liquid medium, in