Sample records for fluorocarbons

  1. Fluorocarbon associative polymers

    Microsoft Academic Search

    Jean-François Berret; Damien Calvet; André Collet; Michel Viguier

    2003-01-01

    Fluorocarbon associative polymers modified along the backbone or at the extremities by hydrophobic groups are reviewed with respect to their association and rheological properties in aqueous solutions. Above a threshold concentration corresponding to the formation of a reversible network structure, the solutions behave as physical gels. In this review, it is shown that the viscoelasticity of fluorocarbon associative polymer gels

  2. water-soluble fluorocarbon coating

    NASA Technical Reports Server (NTRS)

    Nanelli, P.

    1979-01-01

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

  3. Molecular origins of fluorocarbon hydrophobicity

    PubMed Central

    Dalvi, Vishwanath H.; Rossky, Peter J.

    2010-01-01

    We have undertaken atomistic molecular simulations to systematically determine the structural contributions to the hydrophobicity of fluorinated solutes and surfaces compared to the corresponding hydrocarbon, yielding a unified explanation for these phenomena. We have transformed a short chain alkane, n-octane, to n-perfluorooctane in stages. The free-energy changes and the entropic components calculated for each transformation stage yield considerable insight into the relevant physics. To evaluate the effect of a surface, we have also conducted contact-angle simulations of water on self-assembled monolayers of hydrocarbon and fluorocarbon thiols. Our results, which are consistent with experimental observations, indicate that the hydrophobicity of the fluorocarbon, whether the interaction with water is as solute or as surface, is due to its “fatness.” In solution, the extra work of cavity formation to accommodate a fluorocarbon, compared to a hydrocarbon, is not offset by enhanced energetic interactions with water. The enhanced hydrophobicity of fluorinated surfaces arises because fluorocarbons pack less densely on surfaces leading to poorer van der Waals interactions with water. We find that interaction of water with a hydrophobic solute/surface is primarily a function of van der Waals interactions and is substantially independent of electrostatic interactions. This independence is primarily due to the strong tendency of water at room temperature to maintain its hydrogen bonding network structure at an interface lacking hydrophilic sites. PMID:20643968

  4. Fluorinated diamond bonded in fluorocarbon resin

    DOEpatents

    Taylor, Gene W. (Los Alamos, NM)

    1982-01-01

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

  5. Electron attachment to fluorocarbon radicals

    NASA Astrophysics Data System (ADS)

    Shuman, Nicholas

    2014-10-01

    Most plasma environments contain populations of short-lived species such as radicals, the chemistry of which can have significant effects on the overall chemistry of the system. However, few experimental measurements of the kinetics of electron attachment to radicals exist due to the inherent difficulties of working with transient species. Calculations from first principles have been attempted, but are arduous and, because electron attachment is so sensitive to the specifics of the potential surface, their accuracy has not been established. Electron attachment to small fluorocarbon radicals is particularly important, as the data are needed for predictive modeling of plasma etching of semiconductor materials, a key process in the industrial fabrication of microelectronics. We have recently developed a novel flowing afterglow technique to measure several types of otherwise difficult to study plasma processes, including thermal electron attachment to radicals. Variable Electron and Neutral Density Attachment Mass Spectrometry (VENDAMS) exploits dissociative electron attachment in a weakly ionized plasma as a radical source. Here, we apply VENDAMS to a series of halofluorocarbon precursors in order to measure the kinetics of thermal electron attachment to fluorocarbon radicals. Results are presented for CF2, CF3, C2F5,C2F3,1-C3F7, 2-C3F7, and C3F5 from 300 K to 900 K. Both the magnitude and the temperature dependences of rate coefficients as well as product branching between associative and dissociative attachment are highly system specific; however, thermal attachment to all species is inefficient, never exceeding 5% of the collision rate. The data are analyzed using a recently developed kinetic modeling approach, which uses extended Vogt-Wannier theory as a starting point, accounts for dynamic effects such as coupling between the electron and nuclear motions through empirically validated functional forms, and finally uses statistical theory to determine the fate of the highly excited anion intermediate formed during attachment. The kinetic modeling, along with complimentary data from electron beam measurements, is used to extrapolate the electron attachment rate coefficients to temperature and pressure regimes inaccessible to the experiment, including to non-thermal plasma conditions most relevant to plasma etching.

  6. Gain and loss mechanisms in fluorocarbon plasmas

    Microsoft Academic Search

    Caleb Timothy Nelson

    2010-01-01

    Understanding dominant reaction channels for important gas-phase species in fluorocarbon plasmas is crucial to the ability to control surface evolution and morphology. In order to accomplish this goal a modified GEC reference ICP reactor is used in tandem with Fourier transform infrared spectroscopy (FTIR) to measure the densities of stable species. Integrated absorption cross-sections are presented for all fundamental bands

  7. A study on the breakdown characteristics of the fluorocarbon

    SciTech Connect

    Huh, C.S. [Inha Univ., Inchon (Korea, Republic of). Dept. of Electrical Engineering; Lee, J.B. [Korea Electrotechnology Research Inst., Changwon (Korea, Republic of)

    1996-12-31

    In this paper, the authors investigated physical properties and electrical characteristics of the fluorocarbon that used as coolants for large power gas-insulated transformer. Volume resistivity of the fluorocarbon is {rho} = 1.87 {times} 10{sup 15} [Q{center_dot}cm] at 1 atm, 27 C. Dielectric constant is 1.86 and decreases as temperature increases. The breakdown voltage at 1 atm is higher than that of transformer oil. The breakdown voltage of fluorocarbon vapor is about 18 kV when pressure in a test chamber increases over 1 kg/cm{sup 2}. When fluorocarbon is mixed with SF{sub 6} gas, breakdown voltage of the mixed is higher than that of fluorocarbon. Then fluorocarbon leads to increase over 4 kg/cm{sup 2} in pressure as temperature increase. Therefore, when a gas-insulated transformer is manufactured, the design must be taken into consideration at high-pressure.

  8. Fluorocarbons and fluorinated amphiphiles in drug delivery and biomedical research

    Microsoft Academic Search

    Marie Pierre Krafft

    2001-01-01

    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

  9. Fluorocarbon adsorption in hierarchical porous frameworks.

    PubMed

    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

    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

  10. Fluorocarbon adsorption in hierarchical porous frameworks

    NASA Astrophysics Data System (ADS)

    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

    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.

  11. Decontamination by cleaning with fluorocarbon surfactant solutions

    SciTech Connect

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

    1994-02-01

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

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

    DOEpatents

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

    1985-01-01

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

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

    DOEpatents

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

    1983-11-14

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

  14. Mass and energy spectroscopy of fluorocarbon plasmas.

    NASA Astrophysics Data System (ADS)

    Rees, J. A.

    2008-10-01

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

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

    NASA Astrophysics Data System (ADS)

    Abraham-Shrauner, Barbara

    2003-10-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  17. Fluoro-Carbonate Solvents for Li-Ion Cells

    SciTech Connect

    NAGASUBRAMANIAN,GANESAN

    1999-09-17

    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.

  18. New Fluorescent Probes Applicable to Aggregates of Fluorocarbon Surfactants

    Microsoft Academic Search

    Tadahiro Ozawa; Tsuyoshi Asakawa; Akio Ohta; Shigeyoshi Miyagishi

    2007-01-01

    We developed new benzofurazan (NBD) labeled probes for fluorocarbon surfactant systems. The fluorescence behavior depended on the solubilization site of the fluorescent probes in the surfactant aggregates. The NBD-labeled probes suffered virtually complete reduction in the presence of Na2S2O4 owing to the solubilization at the surface of 2-hydroxy-1,1,2,3,3-pentahydroperfluoroundecyldiethylammonium bromide (FC8DAB) aggregates. On the other hand, N-(3-sulfopropyl)acridinium (SPA) in FC8DAB aggregates

  19. Diagnostics of inductive and capacitive plasmas in fluorocarbon gases

    Microsoft Academic Search

    Jean-Paul Booth

    2001-01-01

    Plasmas in fluorocarbon-based gas mixtures are widely used for selective anisotropic etching of sub-micron features in SiO2 thin films. Whereas inductively-coupled plasmas have become the industry standard for etching of Si and metals (using Cl_2-based chemistries), their use for SiO2 etching has been abandoned in favor of dual frequency capacitive sources. This has been for a number of reasons, including

  20. Reaction of uranium and the fluorocarbon FC-75

    SciTech Connect

    Young, R.H.

    1985-04-04

    Because of criticality concerns with water cooling in enriched uranium upgrading, a fluorocarbon has been evaluated as a replacement coolant for internal module components in the Plasma Separation Process (PSP). The interaction of bulk uranium and of powdered uranium with FC-75 has been investigated at temperatures between 200 and 700/sup 0/C. The gas pressure and the metal temperature were monitored as a function of time. Modest temperature changes of 50 to 100/sup 0/C were observed for the bulk uranium/fluorocarbon reaction. Much larger changes (up to 1000/sup 0/C) were noted for the reaction involving high surface area uranium powder. These temperature transients, particularly for the powdered uranium reaction, were short-lived (<10 seconds) and indicative of the formation of a protective layer of reaction products. Analysis of residual gas products by infrared spectroscopy indicated that one potentially serious hazard, UF/sub 6/, was not present; however, several small toxic fluorocarbons were produced by thermolysis and/or reaction. X-ray diffraction analysis of the residual solids indicated UF/sub 4/ and UO/sub 2/ were the major solid products. 5 refs., 11 figs., 1 tab.

  1. Effects of nano-fluorocarbon coating on icing

    NASA Astrophysics Data System (ADS)

    Wang, Hong; He, Guogeng; Tian, Qiqi

    2012-07-01

    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.

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

    E-print Network

    Kushner, Mark

    Mechanisms for CF2 radical generation and loss on surfaces in fluorocarbon plasmas Da Zhanga of fluorocarbon radicals incident on polymerized surfaces produce additional CF2 .8 These results imply that reactions of CxFy radicals other than CF2 produced that species at the surface. On the other hand, Sugai

  3. Discovery during Hydrogen Annealing: Formation of Nanoscale Fluorocarbon Tubular Structures

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    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.

  4. Enhanced removal of radioactive particles by fluorocarbon surfactant solutions

    SciTech Connect

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

    1993-08-01

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

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

    NASA Astrophysics Data System (ADS)

    Abraham-Shrauner, Barbara

    2003-10-01

    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.^1 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 C_2F6 etch and deposition on fluorocarbon covered silicon substrates. 1. T.E.F.M. Standaert et al, J. Vac. Sci. and Tech. A, 16, 239 (1998).

  6. Gas Chemistry Dependence of Si Surface Reactions in a Fluorocarbon Plasma during Contact Hole Etching

    NASA Astrophysics Data System (ADS)

    Komeda, Hiroyuki; Ueda, Tohru; Wada, Sakae; Ohmi, Tadahiro

    1998-03-01

    Gas chemistry dependence of Si surface reactions in a high C/F ratio fluorocarbon plasma during contact hole etching was investigated. CO and C4F8 were selected as additional gases for CF4/CHF3/Ar chemistry. CO addition increased the neutral carbon density in the plasma, C4F8 addition increased not only the fluorocarbon radicals but also the fluorocarbon ion flux. Although both gases enhanced the deposition rate of the fluorocarbon film on the Si surface, there is a difference in the mechanism of the film deposition. CO addition increased the radical sticking site in the fluorocarbon film deposited on the Si surface due to an abundant carbon density in the plasma. C4F8 addition increased the precursor radical density in the plasma due to the electron impact dissociation of C4F8. Since damage formation depends on the fluorocarbon ion flux, increasing of the fluorocarbon ion flux by C4F8 addition enhanced the damage formation.

  7. Health effects among refrigeration repair workers exposed to fluorocarbons.

    PubMed Central

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

    1986-01-01

    Refrigeration repair workers may be intermittently exposed to fluorocarbons and their thermal decomposition products. A case of peripheral neuropathy (distal axonopathy) in a commercial refrigeration repairman prompted an epidemiological investigation of the health of refrigeration repair workers. No additional cases of peripheral neuropathy were identified among the 27 refrigeration repair workers studied. A reference group of 14 non-refrigeration repair workers was also studied. No differences were noted between groups for the ulnar (motor and sensory), median (motor and sensory), peroneal, sural, or tibial nerve conduction velocities. Refrigeration repair workers reported palpitations and lightheadedness significantly more often than workers in the reference group. No clinical neurological or electroneurophysiological abnormalities were detected in eight refrigeration repair workers followed up for three years during continuous employment. PMID:3004555

  8. Selective Plasma Deposition of Fluorocarbon Films on SAMs

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

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

    Microsoft Academic Search

    Yasuhiko H. Mori; Keiji Kaminaga; Takashi Ando

    1990-01-01

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

  10. Adhesion of metals to spin-coated fluorocarbon polymer films

    NASA Astrophysics Data System (ADS)

    Kim, Yong-Kil; Chang, Chin-An; Schrott, A. G.

    1990-01-01

    Adhesion between metals and fluorocarbon polymer films has been studied for Cu, Cr, Ti, Al, and Au on polytetrafluoroethylene (PTFE) and tetrafluoroethylene-hexafluoropropylene copolymer (FEP) films. Polymer films were applied on the Cr/SiO2 /Si substrate by spinning the aqueous dispersions of the polymer resin particles, followed by thermal curing. Strips of different metals were deposited on the polymers, and adhesion was measured at 90° peel test. The peel strengths were invariably higher for the metals on FEP than those of the corresponding metals on PTFE. Among the metals, Ti showed the highest peel strength for both polymers, followed by Cr and Al, with Cu and Au being the lowest. The peel strengths of Ti, Cr, and Cu on FEP are 85, 45, and 12 g/mm, respectively, and the corresponding ones on PTFE are 23, 5, and 2 g/mm, respectively. X-ray photoelectron spectroscopic analysis shows that the metal-polymer bonding involves the metal-carbon interactions. The strongest interaction is observed for Ti with the polymers, forming Ti carbidelike bonds. Cr also shows strong interaction with the two polymers, but to a lesser degree compared with Ti. Only a weak bonding is shown for Cu. The difference in peel strengths among the metals shows a correlation with the difference in electronegativities between the metals and carbon. Little contribution to the observed peel strengths is seen from the surface morphological analysis of the untreated polymers.

  11. Roughening of porous SiCOH materials in fluorocarbon plasmas

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

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

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

    SciTech Connect

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

    2004-09-21

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

  13. The environmental history and probable future of Fluorocarbon 11

    SciTech Connect

    Khalil, M.A.K.; Rasmussen, R.A. [Oregon Graduate Institute, Portland, OR (United States)

    1993-12-01

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

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

    ERIC Educational Resources Information Center

    Mahaffy, Cheryl

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

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

    NASA Astrophysics Data System (ADS)

    Hallewell, G.

    2011-05-01

    The excellent dielectric properties of saturated fluorocarbons have allowed their use in direct immersion liquid cooling of electronics, including supercomputers and as heat transfer media in vapour phase soldering and burn-in testing of electronics. Their high density, UV transparency, non-flammability, non-toxicity and radiation tolerance have led to their use as liquid and gas radiator media for RICH detectors in numerous particle physics experiments. Systems to circulate and purify saturated fluorocarbon Cherenkov radiator vapours often rely on thermodynamic evaporation-condensation cycles similar to those used in refrigeration. Their use as evaporative refrigerants was pioneered for the ATLAS silicon tracker, and they are now also used as evaporative coolants in ALICE and TOTEM and as liquid coolants in ATLAS and CMS. Ultrasonic techniques for vapour phase analysis of fluorocarbon mixtures—developed for the SLAC SLD barrel CRID radiator during the 1980s as an alternative to UV refractometry are again under development for the ATLAS tracker evaporative cooling system. Examples of fluorocarbon circulation systems, together with purification and analysis techniques for these versatile fluids are mentioned.

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

    PubMed

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

    2010-11-01

    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

  17. The environmental history and probable future of fluorocarbon-11

    NASA Astrophysics Data System (ADS)

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

    1993-12-01

    The atmospheric concentration of fluorocarbon 11 (F-11) has increased steadily since it was first put into commercial use in the late 1930s and early 1940s. The observed trends, however, have two periods of dramatic declines. The first occurred around 1974, when trends started falling from their all time high of 13.8 pptv/yr down to around 7.8 pptv/yr (1 pptv = 10-12 parts by volume) in 1982. This decline occurred at first, probably, because of market conditions and later because of the ban in the United States on inessential uses of F-11, particularly in aerosol spray cans. In the meantime, other uses of F-11, such as blowing foams, increased, causing an increasing trend once again until around 1987, when the atmospheric trends reached 11 pptv/yr (measured 1986-1988, inclusive). After this time, however, the trends have fallen dramatically and are now only 4.6 pptv/yr (measured 1990-1992) and even lower in the middle northern latitudes (about 2 pptv/yr). The recent decline of trend is attributed to the effect of the Montreal Protocol and subsequent agreements that are designed to ban worldwide production before the turn of this century. The atmospheric trends reflect estimated emissions, which reached highest values in 1974 (340-355 Gg/yr; 1 Gg = 109g) and again in 1988 (314-380 Gg/yr). The observed concentrations and trends agree extremely well with those calculated from independent estimates of emissions from the various sources. Atmospheric concentrations of F-11 are calculated from a mass balance theory involving seven reservoirs and their interactions. Three of the reservoirs are at the Earth's surface arising from the uses of F-11 (quick-release applications such as open cell foams and aerosols, nonhermetically sealed refrigeration, and rigid polyurethane foams). We estimate that of the 9150 Gg of F-11 that have been produced throughout its history, at present about 1040 Gg are tied up in rigid foams (90 Gg and 24 Gg are tied up in refrigeration and quick-release applications, respectively). There are four environmental reservoirs (deep oceans, the ocean mixed layer, the troposphere, and the stratosphere). F-11 is dynamically exchanged between these reservoirs and is destroyed principally by photolysis in the stratosphere and by soils at the Earth's surface. At present there are about 5360 Gg in the troposphere, 740 Gg in the stratosphere, and small amounts in the oceans (27 Gg and 6 Gg in the mixed layer and deep oceans, respectively). About 81% of the 9 Tg of F-11 produced is still in the surface or environmental reservoirs (1 Tg = 1012g). The future concentrations of F-11 depend on leakage rates from the surface reservoirs and the atmospheric lifetime. It seems that concentrations are not likely to reach the peaks expected earlier and are likely to decline faster than previously thought. The peak concentration is expected to be about 275 pptv and may occur within the next 2 to 3 years. This abstract, the figures, and their captions form a self-contained condensed description of our results.

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

    Microsoft Academic Search

    Toshiro Kamiusuki; Takashi Monde; Nobuyuki Nakayama; Koji Yano; Toshinobu Yoko; Takeo Konakahara

    1999-01-01

    Glassesand silica-gel packings modified with fluorocarbon and hydrocarbon silylation agents were prepared to investigate the separation mechanism of a fluorocarbon bonded layer in reversed-phase high-performance liquid chromatography (RP-HPLC). On the hydrocarbon layer the contact angles of benzene (Be) and hexafluorobenzene (FB) decreased with increasing carbon chain length of the modifier, and the mobile phase (MP) was independent of the modifier.

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

    NASA Astrophysics Data System (ADS)

    Hwui Lee, Sang; Lu, Jian-Qiang

    2010-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

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

  1. Total electron scattering cross section of Fluorocarbons at intermediate electron energies

    NASA Astrophysics Data System (ADS)

    Palihawadana, Prasanga; Villela, Gilberto; Ariyasinghe, Wickramasinghe

    2008-10-01

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

  2. Investigation of fluorocarbon thin films as dielectric materials for electronic applications

    Microsoft Academic Search

    P. Gonon; A. Sylvestre; E. Bustarret

    2003-01-01

    We investigated fluorocarbon thin films as dielectric materials for electronics. Films were deposited by RF magnetron sputtering of PTFE. Their structural properties were investigated using XPS, FTIR, and TGA analysis. Films have a stoichiometry close to CF2. They incorporate C-C, CF, CF2 and CF3 bonds (11%, 61%, 20%, and 8% respectively). Films start to decompose around 200°C. Insulating properties were

  3. Arterial blood gases and brain oxygen availability following infusion of intratracheal fluorocarbon neat liquids.

    PubMed

    Hoffmann, R E; Bhargava, H K; Davis, S L; Clark, L C

    1992-01-01

    Eight adult New Zealand Swiss rabbits (3-5 kg) having previously implanted chronic bilateral platinum electrodes in the visual cerebral cortex and subcutaneous silver reference electrodes were tranquilized and monitored in multiple 2-3 hour sessions using voltammetric techniques. Six of these were given intratracheal neat liquid fluorocarbons ranging in boiling point from 132 degrees C to 215 degrees C at doses of 2 or 4cc/kg. Each animal received only one fluorocarbon liquid. Two additional rabbits were match-studied as controls. Half of the rabbits have survived more than five months. Both controls and two experimental rabbits were sacrificed after more than seven months due to gastric hairballs. The period of daytime monitoring sessions, when cathodic brain oxygen currents (aO2), arterial blood gases and pH were obtained, was between 34 and 263 days. In some animals the arterial pCO2 was increased during the first week but the pO2 and pH remained nearly normal in all eight animals throughout. The two best fluorocarbons for liquid breathing on the basis of this limited but intensive work are F-methyldecalin and F-5,6H-dec-5-ene (F44E). PMID:1391429

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

    PubMed

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

    2010-11-01

    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

  5. Surface characterization and platelet adhesion studies on fluorocarbons prepared by plasma-induced graft polymerization.

    PubMed

    Lin, J C; Tiong, S L; Chen, C Y

    2000-01-01

    It is believed that the interactions between the biological environment and biomaterial surface are the key factors influencing its biocompatibility. Therefore, plasma processing, which can vary the surface properties without altering the bulk properties, has been considered as one of the important techniques for improving a materials' biocompatibility. In this investigation, plasma-induced grafting polymerization of vinylidene fluoride (VDF) and chlorotrifluoroethylene (CTFE), instead of direct plasma polymerization, was attempted with an aim to improve the substrate blood compatibility. Contact angle measurement indicated both fluorocarbon-grafted Pdyethylenes (PEs) are hydrophobic. Due to the additional fluorine and chlorine atoms on the CTFE chain, the PCTFE-grafted PE exhibited a higher hydrophobicity than the PVDF-grafted one. ESCA analysis has revealed that these two plasma-induced fluorocarbon deposits contain almost no CFx (x > 2) binding on the surface layer, indicating the grafting polymerization mainly follows the free radical mechanism instead of the molecule-highly-fragmented reaction steps commonly seen in the direct plasma polymerization treatment. In addition, ATR-FTIR has shown the surface chemical configuration of these PVDF- and PCTFE-grafted PEs to be very similar to those of the bulk samples of PVDF and PCTFE. The surface roughness decreased after oxygen plasma treatment and was further reduced by VDF and CTFE grafting polymerization. In vitro platelet adhesion testing indicated these two fluorocarbon grafted PEs are less platelet-activating than the nontreated PE control and oxygen plasma activated one. PMID:11011768

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

    NASA Technical Reports Server (NTRS)

    Alston, W. B.

    1973-01-01

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

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

    SciTech Connect

    Hogen-Esch, T.E.

    1996-11-01

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

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

    SciTech Connect

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

    2014-05-04

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

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

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

    SciTech Connect

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

    2008-09-15

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

  11. Synthesis, thermal properties, and cytotoxicity evaluation of hydrocarbon and fluorocarbon alkyl ?-D-xylopyranoside surfactants.

    PubMed

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

    2012-02-15

    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 (-C(6)H(13) to -C(16)H(33)) and fluorocarbon (-(CH(2))(2)C(6)F(13)) 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

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

    NASA Astrophysics Data System (ADS)

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

    2009-03-01

    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.

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

    E-print Network

    Kushner, Mark

    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

  14. Behaviors of CFx Radicals in ECR Fluorocarbon Plasmas and Control of SiO2 Etching by Radical Injection

    NASA Astrophysics Data System (ADS)

    Goto, Toshio; Hori, Masaru

    1996-10-01

    indent=5mm In SiO_2/Si selective etching processes using fluorocarbon plasmas, the etching selectivity is affected by the surface reactions of CFx radicals. Therefore, it is necessary to obtain information on the behaviors of the CFx radicals in fluorocarbon plasmas and their surface reactions. We developed the in-situ measurement method of radicals in plasma by infrared diode laser absorption spectroscopy (IRLAS) and could be measured the CFx (x=1-3) radicals in the on-off modulated ECR plasmas using CHF_3, CF_4, C_2F6 and C_4F8 for the first time. It was shown from those measurements that the CFx radical densities, the deposition rate of the fluorocarbon film on the substrate and also the SiO_2/Si etching selectivity could be controlled with changing the duty ratio of the on-off modulated ECR CHF3 plasma and that the CF2 radical was an important precursor of the fluorocarbon film formation. Moreover, we have recently developed radical injection techniques into plasma (RIT) to know the important radical for the plasma etching process. The heated HFPO gas was flown into the process chamber and the CF2 radical density of about 1×10^13 cm-3 (at 900 K) was obtained in t he present experiment. In the Ar and H_2/Ar ECR downstream plasmas with CF2 radical injection, the deposition rates of fluorocarbon films formed on Si surfaces and the etching rates of Si and SiO2 were measured. It was shown that the fluorocarbon film was formed from the CF2 radical under the assist of the ion flux, and in the ECR H_2/Ar plasma where the carbon-rich (F/C=0.4) fluorocarbon film was formed, the high SiO_2/Si etching selectivity was obtained. These results will be useful for the developments of ultrafine plasma process technology. In this review, the results on the behaviors of the CFx radicals in the on-off modulated ECR CHF3 plasma and the highly selective etching of SiO_2/Si in the ECR H_2/Ar downstream plasma with CF2 radical injection are described.

  15. Reverse water-in-fluorocarbon microemulsions stabilized by new polyhydroxylated nonionic fluorinated surfactants.

    PubMed

    Debbabi, Khaled; Guittard, Frederic; Eastoe, Julian; Rogers, Sarah; Geribaldi, Serge

    2009-08-18

    New polyhydroxylated nonionic perfluorosurfactants CnF2n+1-CH2-O-SO2-NHCONH-C(CH2OH)3 have been synthesized, and their capacity for stabilization of reverse water-in-fluorocarbon microemulsions has been extensively studied. These investigations showed that, regardless of the composition used, transparent one-phase systems could not be obtained if the fluorinated surfactants were used without a sufficient amount of a semifluorinated alcohol. The mixed oil phase used to prepare microemulsions consisted of a 9:1 mixture of perfluorohexane and 1H,1H,2H,2H-perfluorohexan-1-ol. Various scattering techniques, dynamic light scattering (DLS), small-angle X-ray (SAXS), and neutron scattering (SANS) have been used for structural characterization of these fluorinated microemulsions. Valuable information on the size, shape, and internal colloidal structure in these novel fluorinated microemulsions is described and discussed. PMID:19344159

  16. Hierarchical ZnO particles grafting by fluorocarbon polymer derivative: Preparation and superhydrophobic behavior

    NASA Astrophysics Data System (ADS)

    Gao, Dahai; Jia, Mengqiu

    2015-07-01

    Superhydrophobic surfaces on the basis of hierarchical ZnO particles grafted by fluoroethylene-vinylether (FEVE) polymer derivative were prepared using a facile, mild and low-cost method. X-ray diffraction (XRD) and scanning electron microscope (SEM) revealed that the resulting ZnO particles via hydrothermal process exhibit micro-nano dual-scale morphology with high purity under a suitable surfactant amount and alkali concentration. The grafting of FEVE derivative was confirmed by Fourier transform infrared spectroscopy (FTIR) and energy-dispersive X-ray spectrometer (EDS), suggesting that hierarchical surface of ZnO particles was an imported monomolecular layer of fluorocarbon polymer. The obtained surface fabricated by drop-casting shows considerably high contact angle and good resistance to water immersion. The wetting behavior in this work was furthermore analyzed by theoretical wetting model. This work demonstrates that the sufficient low-wettable surface and high roughness both take a vital role in the superhydrophobic behavior.

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

    PubMed Central

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

    2014-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1974-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

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

    PubMed

    Krafft, Marie Pierre

    2015-08-14

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

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

    SciTech Connect

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

    2010-01-01

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

  2. Assembly and Structure of ?-Helical Peptide Films on Hydrophobic Fluorocarbon Surfaces

    PubMed Central

    Weidner, Tobias; Samuel, Newton T.; McCrea, Keith; Gamble, Lara J.; Ward, Robert S.; Castner, David G.

    2014-01-01

    The structure, orientation and formation of amphiphilic ?-helix model peptide films on fluorocarbon surfaces has been monitored with sum frequency generation (SFG) vibrational spectroscopy, near edge X-ray absorption fine structure (NEXAFS) spectroscopy and X-ray photoelectron spectroscopy (XPS). The ?-helix peptide is a 14-mer of hydrophilic lysine and hydrophobic leucine residues with a hydrophobic periodicity of 3.5. This periodicity yields a rigid 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 ?* is likely due to the broad distribution of amide bond orientations inherent to the ?-helical secondary structure. SFG spectra exhibit strong peaks near 2865 cm?1 and 2935 cm?1 related to aligned leucine side chains interacting with the hydrophobic surface. Water modes near 3200 cm?1 and 3400 cm?1 indicate ordering of water molecules in the adsorbed--peptide fluorocarbon surface interfacial region. Amide I peaks observed near 1655 cm?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. PMID:20408730

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

    SciTech Connect

    Not Available

    1992-09-01

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

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

    PubMed Central

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

    2013-01-01

    Abstract Bioprinting is a recent development in tissue engineering, which applies rapid prototyping techniques to generate complex living tissues. Typically, cell-containing hydrogels are dispensed layer-by-layer according to a computer-generated three-dimensional model. The lack of mechanical stability of printed hydrogels hinders the fabrication of high aspect ratio constructs. Here we present submerged bioprinting, a novel technique for freeform fabrication of hydrogels in liquid fluorocarbon. The high buoyant density of fluorocarbons supports soft hydrogels by floating. Hydrogel constructs of up to 30-mm height were generated. Using 3% (w/v) agarose as the hydrogel and disposable syringe needles as nozzles, the printer produced features down to 570-?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

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

    NASA Astrophysics Data System (ADS)

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

    2005-07-01

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

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

    SciTech Connect

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

    1993-12-31

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    Metal-organic and covalent organic frameworks are porous materials characterized by outstanding thermal stability, high porosities and modular synthesis. Their repeating structures offer a great degree of control over pore sizes, dimensions and surface properties. Similarly precise engineering at the nanoscale is difficult to achieve with discrete molecules, since they rarely crystallize as porous structures. Here we report a small organic molecule that organizes into a noncovalent organic framework with large empty pores. This structure is held together by a combination of [N–H···N] hydrogen bonds between the terminal pyrazole rings and [?···?] 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%.

  8. Static light scattering study of fluorocarbon-modified ampholytic acrylamide ionomers

    SciTech Connect

    Watterson, A.C.; Haralabakopoulos, A.; Salamone, J.C. [Univ. of Massachusetts, Lowell, MA (United States)

    1993-12-31

    A series of water-soluble acrylamide ionomers containing small amounts of ampholytic and hydrophobic sites were investigated in dilute aqueous and aqueous salt solutions via static light scattering methods. Elemental analysis verified the ampholytic nature of the polymers while the ion/hydrophobe content was found to be much lower than what was supplied in the feed. Both the molecular weight and radius of gyration exhibited increases with increasing comonomer content to maximum values at 2.5-3.0 mole%. Mw and Rg increased further in 1 M aqueous NaCl and dropped to previous levels in 3 M NaCl. The radius of gyration exhibited sizable increased at 45 and 70{degrees}C in aqueous solution, less so in 1 M NaCl. Dilute aqueous salt expanded the molecules through shielding of the ionic sites, while concentrated aqueous salt increased hydrophobic aggregation decreasing the size of the polymers. At higher temperatures salt ions failed to reach the ionic sites and fluorocarbon aggregation is thought to be responsible for the low radii of gyration.

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

    NASA Astrophysics Data System (ADS)

    Sankaran, Arvind; Kushner, Mark J.

    2003-03-01

    To achieve shorter RC-delay times in integrated circuits low-dielectric-constant (low-k) materials are being investigated for interconnect wiring. Porous silicon dioxide (PS) is one such material. To address scaling issues during fluorocarbon plasma etching of PS, a feature profile model has been integrated with a plasma equipment model. To focus on issues related to the morphology of porous materials, the PS was treated as stoichiometric SiO2. The model was validated by comparison to experiments for PS etching in CHF3 plasmas sustained in an inductively coupled reactor. We found that etch rates (ER) for PS are generally higher than for SiO2 due to the inherent smaller mass density, although ER do not necessarily scale linearly with pore size or porosity. Mass-corrected ER can be either larger or smaller than that of solid SiO2. For example, in polymerizing environments, at high porosities and large pore radii, there is a reduction in ER due to pore filling with polymer. Profile scaling parameters, such as for tapering, observed for solid SiO2, are generally applicable to PS.

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

    NASA Astrophysics Data System (ADS)

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

    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.

  11. Mechanism of selective Si 3N 4 etching over SiO 2 in hydrogen-containing fluorocarbon plasma

    Microsoft Academic Search

    Lele Chen; Linda Xu; Dongxia Li; Bill Lin

    2009-01-01

    This paper describes the mechanism of selective Si3N4 etching over SiO2 in capacitively-coupled plasmas of hydrogen-containing fluorocarbon gas, including CHF3, CH2F2 and CH3F. The etch rate of Si3N4 and SiO2 is investigated as a function of O2 percentage in all plasma gases. Addition of O2 in feed gases causes plasma gas phase change especially H density. The SiO2 etch rate

  12. Feature Profile Evolution of SiO2 Trenches In Fluorocarbon Plasmas

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Zellner, Reinhard

    1990-01-01

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

  14. 157 nm Pellicles (Thin Films) for Photolithography: Mechanistic Investigation of the VUV and UV-C Photolysis of Fluorocarbons

    SciTech Connect

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

    2005-06-15

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

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

    NASA Astrophysics Data System (ADS)

    Szymczyk, Katarzyna

    2014-03-01

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

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

    NASA Astrophysics Data System (ADS)

    Sankaran, Arvind; Kushner, Mark J.

    2004-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2000-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Sankaran, Arvind; Kushner, Mark J.

    2004-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

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

    SciTech Connect

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

    2007-07-15

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

  3. Langmuir probe measurements in an inductively coupled plasma: Electron energy distribution functions in polymerizing fluorocarbon gases used for selective etching of SiO2

    NASA Astrophysics Data System (ADS)

    Gaboriau, Freddy; Peignon, Marie-Claude; Cartry, Gilles; Rolland, Laetitia; Eon, David; Cardinaud, Christophe; Turban, Guy

    2002-05-01

    We are interested in the silicon oxide deep etching by inductively coupled fluorocarbon plasmas for integrated optical applications. The understanding and the improvement of this process requires to know at least the electrical characteristics of the plasma (electron and ion densities, electronic temperature,…). Up to now, very few measurements in these plasmas have been published because of problems encountered when using Langmuir probes in depositing environments. In the present article, we report problems we met and solutions we brought, and then present electron energy distribution function (EEDF) measurements in very polymerizing gases such as CHF3 and CHF3/CH4 mixtures. Experiments have been performed over a wide range of experimental conditions, from 3 to 50 mTorr and from 200 to 2000 W inductive power. The shape of the EEDF and the evolution of the plasma electrical characteristics with experimental conditions are discussed. Finally, we point out the presence of a large negative ion fraction when increasing the pressure, particularly in pure CHF3 plasmas.

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

    NASA Astrophysics Data System (ADS)

    Rueger, Neal R.

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

  5. Rayleigh scattering measurements of several fluorocarbon gases.

    PubMed

    Zadoo, Serena; Thompson, Jonathan E

    2011-11-01

    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

  6. Decontamination by cleaning with fluorocarbon surfactant solutions

    Microsoft Academic Search

    R. Kaiser; C. E. Benson; E. S. Meyers; V. C. A. Vaughen

    1994-01-01

    In the nuclear industry, facilities and their components inevitably become contaminated with radioactive materials. This report documents the application of a novel particle-removal process developed by Entropic Systems, Inc. (ESI), to decontaminate critical instruments and parts that are contaminated with small radioactive particles that adhere to equipment surfaces. The tests were performed as a cooperative effort between ESI and the

  7. 21 CFR 177.1380 - Fluorocarbon resins.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...of nominally 50 mole percent of ethylene and 50 mole percent of chlorotrifluoroethylene. The copolymer shall have a melting point of 239 to 243 °C and a melt index of less than or equal to 20 as determined by ASTM Method D 3275-89...

  8. 21 CFR 177.1380 - Fluorocarbon resins.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...of nominally 50 mole percent of ethylene and 50 mole percent of chlorotrifluoroethylene. The copolymer shall have a melting point of 239 to 243 °C and a melt index of less than or equal to 20 as determined by ASTM Method D 3275-89...

  9. Experimental and modeling studies of fluorocarbon plasmas

    Microsoft Academic Search

    H. Singh; A. Fiala; J. W. Coburn; M. Li; D. B. Graves

    1997-01-01

    The comparison of experimental results with model predictions is the key to developing and validating plasma chemistry models. We report the comparison of experimental results with the predictions of a hybrid model for a cylindrical ICP over a range of powers and pressures. Mass resolved ion energy distributions are measured by a electrostatic energy analyzer and a mass spectrometer. Modulated

  10. Hydrocarbon versus fluorocarbon in the electrodeposition of superhydrophobic polymer films.

    PubMed

    Darmanin, Thierry; Taffin de Givenchy, Elisabeth; Amigoni, Sonia; Guittard, Frédéric

    2010-11-16

    To elaborate on superhydrophobic surfaces, we report the electrochemical synthesis, surface morphology, and wettability of hydrocarbon conductive polymer films obtained by the electrodeposition of polythiophene, poly(3,4-ethylenedioxythiophene) (i.e., PEDOT), and poly(3,4-ethylenedioxypyrrole) (i.e., PEDOP) derivatives. Highly hydrophobic films were obtained from n-C(14)H(29) and n-C(8)H(17) chains in the cases of polythiophenes and PEDOP, respectively. By contrast, superhydrophobic films were formed by the deposition of PEDOT substituted with n-C(10)H(21) chains (PEDOT-methyl undecanoate): static contact angle ? 160.6°, hysteresis ? 2°, and sliding angle ? 3°. Their surface properties were compared to those of previously reported fluorinated analogues. The water-repellent properties of PEDOT-methyl undecanoate were similar to the best surface properties obtained with fluorinated monomers. Even if the main approach for the chemical factor to build up superhydrophobic surfaces is via a coating of a fluorinated compound, this work confirms that the formation of fractal surfaces is able to achieve super-anti-wetting properties within a hydrocarbon series (less expensive with a favorable ecotoxic approach), and it opens a new path to bioinspired surfaces. PMID:20879773

  11. Sensitivity behavior of tin oxide based semiconducting sensor for fluorocarbons

    Microsoft Academic Search

    B. B. Rao; V. J. Rao

    1999-01-01

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

  12. The dissociative recombination of fluorocarbon ions: II. CF+

    NASA Astrophysics Data System (ADS)

    Novotny, O.; Mitchell, J. B. A.; LeGarrec, J. L.; Florescu-Mitchell, A. I.; Rebrion-Rowe, C.; Svendsen, A.; El Ghazaly, M. A.; Andersen, L. H.; Ehlerding, A.; Viggiano, A. A.; Hellberg, F.; Thomas, R. D.; Zhaunerchyk, V.; Geppert, W. D.; Montaigne, H.; Kaminska, M.; Österdahl, F.; Larsson, M.

    2005-05-01

    The dissociative recombination and excitation of CF+ have been measured at the ASTRID and CRYRING storage rings. Though examination of the available potential energy curves would suggest that the recombination rate would be large for this ion, in fact a rate constant of 5.2 ± 1.0 × 10-8 (Te/300)-0.8 cm3 s-1 was found. The recombination cross section at low energies falls off to a minimum at 0.5 eV centre-of-mass collision energy but exhibits resonances at energies above this. The dissociative excitation cross section leading to C+ + F was also measured and this displays an onset beginning at about 7 eV.

  13. Evaluation of unsaturated fluorocarbons for dielectric Etch applications

    E-print Network

    Chatterjee, Ritwik, 1974-

    2003-01-01

    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 ...

  14. Plaque-controlling surface modifier containing fluorocarbon chain

    Microsoft Academic Search

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

    1998-01-01

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

  15. Attenuation of fluorocarbons released from foam insulation in landfills.

    PubMed

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

    2007-11-15

    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

  16. Estimated historic emissions of fluorocarbons from the European Union

    NASA Astrophysics Data System (ADS)

    McCulloch, A.; Midgley, P. M.

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

  17. Thermal Conductivity of Nonazeotropic Gaseous Mixtures of Fluorocarbon Refrigerants

    NASA Astrophysics Data System (ADS)

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

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

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

    Microsoft Academic Search

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

    1996-01-01

    Currently, there is no reliable and readily accessible technique with which the distribution and diffusion of blowing agents in rigid insulating foams can be detected and monitored. In this paper, we demonstrate that 19F NMR microscopic imaging together with 19F solid-state MAS NMR spectroscopy is ideally suited for such measurements and yield quantitatively reliable information that will be critical to

  19. Evaluating the Robustness of Top Coatings Comprising Plasma-Deposited Fluorocarbons in Electrowetting Systems

    Microsoft Academic Search

    Dimitrios P. Papageorgiou; Elias P. Koumoulos; Costas A. Charitidis; Andreas G. Boudouvis; Athanasios G. Papathanasiou

    2012-01-01

    Thin dielectric stacks comprising a main insulating layer and a hydrophobic top coating are commonly used in low voltage electrowetting systems. However, in most cases, thin dielectrics fail to endure persistent electrowetting testing at high voltages, namely beyond the saturation onset, as electrolysis indicates dielectric failure. Careful sample inspection via optical microscopy revealed possible local delamination of the top coating

  20. Evaluating the robustness of top coatings comprising plasma-deposited fluorocarbons in electrowetting systems

    Microsoft Academic Search

    Dimitrios P. Papageorgiou; Elias P. Koumoulos; Costas A. Charitidis; Andreas G. Boudouvis; Athanasios G. Papathanasiou

    2011-01-01

    Thin dielectric stacks comprising a main insulating layer and a hydrophobic top coating are commonly used in low voltage electrowetting systems. However, in most cases, thin dielectrics fail to endure persistent electrowetting testing at high voltages, namely beyond the saturation onset, as electrolysis indicates dielectric failure. Careful sample inspection via optical microscopy revealed possible local delamination of the top coating

  1. Influence of fluorocarbon flat-membrane hydrophobicity on carbon dioxide recovery.

    PubMed

    Lin, Su-Hsia; Tung, Kuo-Lun; Chang, Hao-Wei; Lee, Kueir-Rarn

    2009-06-01

    The influence of hydrophobicity in flat-plate porous poly(vinylidene fluoride) (PVDF) and expended polytetrafluoroethylene (PTFE) membranes on CO(2) recovery using aqueous solutions of piperazine (PZ) and alkanolamine is examined. Experiments were conducted at various gas flow rates, liquid flow rates, and absorbent concentrations. The CO(2) absorption flux increased with increasing gas flow rates and absorbent concentrations. When using 2-amino-2-methyl-1-propanol (AMP) or AMP+PZ aqueous solution as absorbent, this process was dominantly governed by gas film layer diffusion and membrane diffusion. The diffusion resistance of the membrane phase was only important when using N-methyldiethanolamine as the sole absorbent. The water contact angle increased initially with increasing plasma working power and reached at steady state value of 155 degrees beyond 100 W. The elemental fluorine-to-carbon ratio (F/C) and water contact angle of the PVDF membrane increased with increasing treatment time and reached a plateau after 5min of CH(4) plasma (100 W). Increases in the CO(2) absorption fluxes of 7% and 17% were observed for plasma-treated PVDF membranes in comparison to non-treated PVDF and PTFE, respectively, when using 1M AMP as absorbent. The membrane mass transfer coefficient, k(m), for plasma-treated PVDF membranes increased from 2.1 x 10(-4) to 2.5 x 10(-4)ms(-1). Membrane durability was greatly improved by CF(4) plasma treatment (100 W/5 min) and comparable to that of PTFE membranes. PMID:19289246

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

    Microsoft Academic Search

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

    2000-01-01

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

  3. MultiDimensional Simulations of Fluorocarbon Plasmas with Ion Energy Resolved Surface Reaction Rates

    Microsoft Academic Search

    Ning Zhou; Vladimir Kolobov; Vladimir Kudriavtsev

    2001-01-01

    The commercial CFD-ACE+ software has been extended to account for ion energy dependent surface reactions. The ion energy distribution function and the mean ion energy at a biased wafer were obtained using the Riley sheath model extended by the NASA group (Bose et al., J. Appl. Phys. v.87, 7176(2000)). The plasma chemistry model (by P. Ho et al., SAND2001-1292) consisting

  4. Nanostructure imaging mass spectrometry: the role of fluorocarbons in metabolite analysis and yoctomole level sensitivity.

    PubMed

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

    2015-01-01

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

  5. Deposition of super-hydrophobic fluorocarbon coatings in modulated RF glow discharges

    Microsoft Academic Search

    P. Favia; G. Cicala; A. Milella; F. Palumbo; P. Rossini; R. d'Agostino

    2003-01-01

    Superhydrophobic coatings were deposited in modulated RF glow discharges fed with tetrafluorothylene. Such coatings are characterized by a high fluorination degree, ribbon-like randomly distributed surface microstructures, and a certain crystallinity. Combined high fluorination degree and surface texture\\/roughness leads to the super hydrophobic behaviour, as attested by water contact angle values of 150° and more. The coatings were characterized by means

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

    E-print Network

    Murthy, Shashi Krishna, 1977-

    2003-01-01

    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 ...

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

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

  8. Recruitment and Immobilization of a Fluorinated Biomarker Across an Interfacial Phospholipid Film using a Fluorocarbon Gas.

    PubMed

    Yang, Guang; O'Duill, Miriam; Gouverneur, Véronique; Krafft, Marie Pierre

    2015-07-13

    Perfluorohexane gas when introduced in the air atmosphere above a film of phospholipid self-supported on an aqueous solution of C2 F5 -labeled compounds causes the recruitment and immobilization of the latter in the interfacial film. When the phospholipid forms a liquid-condensed Gibbs monolayer, which is the case for dipalmitoylphosphatidylcholine (DPPC), the C2 F5 -labeled molecule remains trapped in the monolayer after removal of F-hexane. Investigations involve bubble profile analysis tensiometry (Gibbs films), Langmuir monolayers and microbubble experiments. The new phenomenon was utilized to incorporate a hypoxia biomarker, a C2 F5 -labeled nitrosoimidazole (EF5), in microbubble shells. This finding opens perspectives in the delivery of fluorinated therapeutic molecules and biomarkers. PMID:26068966

  9. 40 CFR Appendix A to Subpart F of... - Specifications for Fluorocarbon and Other Refrigerants

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...Protection Agency; Office of Air and Radiation Docket; 1301 Constitution Ave., NW., Room B108; Washington, DC 20460. Section...No. A-92-01, Environmental Protection Agency, 1301 Constitution Ave., NW., Washington, DC, 20460 or at the...

  10. 40 CFR Appendix A to Subpart F of... - Specifications for Fluorocarbon and Other Refrigerants

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) PROTECTION OF STRATOSPHERIC OZONE Recycling and Emissions Reduction Pt. 82, Subpt. F, App. A Appendix A to Subpart F of Part 82—Specifications for...

  11. 40 CFR Appendix A to Subpart F of... - Specifications for Fluorocarbon and Other Refrigerants

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) PROTECTION OF STRATOSPHERIC OZONE Recycling and Emissions Reduction Pt. 82, Subpt. F, App. A Appendix A to Subpart F of Part 82—Specifications for...

  12. Multi-Dimensional Simulations of Fluorocarbon Plasmas with Ion Energy Resolved Surface Reaction Rates

    NASA Astrophysics Data System (ADS)

    Zhou, Ning; Kolobov, Vladimir; Kudriavtsev, Vladimir

    2001-10-01

    The commercial CFD-ACE+ software has been extended to account for ion energy dependent surface reactions. The ion energy distribution function and the mean ion energy at a biased wafer were obtained using the Riley sheath model extended by the NASA group (Bose et al., J. Appl. Phys. v.87, 7176(2000)). The plasma chemistry model (by P. Ho et al., SAND2001-1292) consisting of 132-step gas-phase reactions and 55-step ion energy dependent surface reactions, was implemented to simulate the C2F6 plasma etching of silicon dioxide in an Inductively Coupled Plasma. Validation studies have been performed against the experimental data by Anderson et al. of UNM for a lab-scale GEC reactor. For a wide range of operating conditions (pressure: 5-25 mTorr; plasma power: 205-495 Watts; bias power: 22-148 Watts), the average etch rate calculated by CFD-ACE+ 2-D simulations agrees very well with those by 0-D AURORA predictions and the experimental data. The CFD-ACE+ simulations allow one to study the radial uniformity of the etch rate depending on discharge conditions.

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

    PubMed

    Kjeldsen, Peter; Scheutz, Charlotte

    2003-11-01

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

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

    PubMed

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

    2007-12-01

    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

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

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Niki, Hiromi

    1990-01-01

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

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

    SciTech Connect

    Lagow, R.J.

    1982-12-01

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

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

    SciTech Connect

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

    2011-07-01

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

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

    Microsoft Academic Search

    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

    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

  20. Silicon surface damage caused by reactive ion etching in fluorocarbon gas mixtures containing hydrogen

    SciTech Connect

    Norstroem, H. (Ericsson Components AB, S-164 81 Kista-Stockholm (Sweden)); Blom, H. (Institute of Technology, S-751 21 Uppsala (Sweden)); Ostling, M. (Royal Institute of Technology, Department of Solid State Electronics-Electrum, S-164 28 Kista (Sweden)); Nylandsted Larsen, A. (Institute of Physics, University of Aarhus, Dk-8000 Aarhus C, (Denmark)); Keinonen, J. (University of Helsinki, Accelerator Laboratory, Haemeentie 100, SF-00550, Helsinki 55 (Finland)); Berg, S. (Institue of Technology, S-751 21, Uppsala (Sweden))

    1991-01-01

    For selective etching of SiO{sub 2} on silicon, gases or gas mixtures containing hydrogen are often used. Hydrogen from the glow discharge promotes the formation of a thin film polymer layer responsible for the selectivity of the etching process. The reactive ion etch (RIE) process is known to create damage in the silicon substrate. The influence of hydrogen on the damage and deactivation of dopants is investigated in the present work. The distribution of hydrogen in silicon, after different etching and annealing conditions have been studied. The influence of the RIE process on the charge carrier concentration in silicon has been investigated. Various analytical techniques like contact resistivity measurements, four point probe measurements, and Hall measurements have been used to determine the influence of the RIE process on the electrical properties of processed silicon wafers. The hydrogen profile in as-etched and post annealed wafers was determined by the {sup 1}H({sup 15}N,{alpha}{gamma}){sup 12}C nuclear reaction. The depth of the deactivated surface layer is discussed in terms of the impinging hydrogen ion energy, i.e., the possibility of H{sup +} ions to pick up an energy equal to the peak-to-peak voltage of the rf signal.

  1. High density fluorocarbon plasma etching of new resists suitable for nano-imprint lithography

    Microsoft Academic Search

    K. Pfeiffer; G. Bleidießel; G. Grützner; G TURBAN; C CARDINAUD; G BLEIDIESEL

    2000-01-01

    In this work, we studied etching of resists suitable for nano-imprint lithography. First, various resists have been tested in a SiO2 process under low pressure and high plasma density conditions in order to get the best SiO2\\/resist selectivity. Second, to understand resist etching mechanism and thus optimize the process, we focused our study on polymer etching behavior in different plasma

  2. Etch Characteristics of Silsesquioxane-based Low Dielectric Constant Material in Fluorocarbon Plasma

    NASA Astrophysics Data System (ADS)

    Hwang, Sung-Wook; Lee, Gyeo-Re; Min, Jae-Ho; Moon, Sang Heup; Kim, Yu Chang; Ryu, Hyun-Kyu; Cho, Yun Seok; Kim, Jin Woong

    2002-09-01

    The etch characteristics of hydrido-organo-siloxane-polymer (HOSP), a typical silsesquioxane-based low-dielectric material, were compared with those of silicon dioxide in CF4 and CHF3 plasmas. The etch-rate ratios of the two materials are more significantly affected by the types and pressure of plasma gases than by plasma bias voltage, indicating that the relative etch rates are determined largely by the density of radicals than by the energy of ions incident on the substrate surface. The etching of silsesquioxane is accompanied by an increase in the CF2 radical density and a significant decrease in F radical density, indicating that silsesquioxane is etched via the sequential dissociation of Si-CH3 and cage-like Si-O bonds by reaction with F radicals. Based on the findings herein, we propose that the relative amounts of cage-like and network Si-O bonds remaining in silsesquioxane after etching can be controlled by adjusting the parameter, (F radical density)2/(CF2 radical density).

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

    SciTech Connect

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

    1993-12-31

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

  4. Investigation of growth, coverage and effectiveness of plasma assisted nano-films of fluorocarbon

    E-print Network

    Mukhopadhyay, Sharmila M.

    and graphite, using microwave plasma. X-ray photoelectron spectroscopy (XPS) was used for detailed study of composition and chemistry of the substrate and coating atoms, at all stages of deposition. Atomic force foam and nano fibers. It was seen that these nano-films can be a viable approach for effective surface

  5. Development of fluorocarbon rubber for backup seals of sodium cooled fast breeder reactor

    Microsoft Academic Search

    N. K. Sinha; R. Mukhopadhyay; D. Dhupia; S. Das Gupta; Baldev Raj

    2011-01-01

    The development of a fluorohydrocarbon rubber compound for static backup seals of 500MWe, Prototype Fast Breeder Reactor (PFBR) is depicted. Variations of a previously developed Viton A-401C based formulation were subjected to processability tests, accelerated heat ageing in air, mechanical characterization and production trials. Finite element analysis and literature data extrapolation were combined with long term ageing to ascertain the

  6. 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...

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

    NASA Technical Reports Server (NTRS)

    Niki, Hiromi

    1990-01-01

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

  8. Semiempirical molecular orbital calculations of anisotropic H, C and F hyperfine coupling constants in hydrocarbon and fluorocarbon radicals

    Microsoft Academic Search

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

    1981-01-01

    The anisotropic hyperfine coupling constants (AHCC) from the electron spin resonance (E.S.R.) spectra of a variety of atoms in organic radicals have been calculated by means of semiempirical molecular orbital wavefunctions in the INDO approximation. Hyperfine tensors involving H, C and F nuclei are obtained for the ?H, ?H3, CH3?H2, (CH3)3? hydrocarbon radicals, malonic acid radical, ?H2F, ?F2H, ?F3 and

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

    SciTech Connect

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

    1993-04-01

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

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

    PubMed

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

    2011-02-01

    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

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

    SciTech Connect

    Trowbridge, L.D.

    1999-09-01

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

  12. The characterization of fluorocarbon films on NiTi alloy by magnetron sputtering *, F.T. Zi a

    E-print Network

    Zheng, Yufeng

    , as dielectric inter- connects in microelectronic circuits, as passivation coatings in clinical devices Ultra instrument from Kratos. The morphological characteristics of the deposited films were observed by means of an AJ-IIIa atomic force microscopy (AFM, Shanghai AiJian Co., China). The mechanical properties

  13. NMR chemical shifts in the fluorocarbonate ion FCO 2 ?: a comparative study of experimental and theoretical IGLO NMR results

    Microsoft Academic Search

    Udo Groß; Renate Wolff

    1999-01-01

    Based on the MP2\\/SCF optimized geometry of the FCO2? anion, the nuclear magnetic shielding both at the carbon and fluorine nuclei are calculated by the IGLO–method. The different contributions to the shielding, stemming from the respective bonds, lone pairs and inner electron shells are reported. The calculated chemical shifts are compared to the experimentally observed 13C and 19F-MAS chemical shifts.

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

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

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

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

    E-print Network

    Kushner, Mark

    exposure and development, plasma etching to define vias and trenches, cleaning of the feature etch cleaning of trenches and vias reduces the contact resistance between the plasma-exposed surfaces containing plasmas, there is often a re- sidual oxidized layer on the surface which is typically cleaned

  16. Behavior of F Atoms and CF2 Radicals in Fluorocarbon Plasmas for SiO2/Si Etching

    NASA Astrophysics Data System (ADS)

    Tachibana, Kunihide; Kamisugi, Hideaki; Kawasaki, Takeshi

    1999-07-01

    Densities of F atoms and CF2 radicals were measured in CF4, C2F6 and CHF3 plasmas by vacuum ultraviolet laser absorption and laser-induced fluorescence techniques, respectively, using an RF (400 kHz) plasma source. In the measurement of source gas dependence, the F atom density became highest in CF4 and lowest in CHF3, while the tendency was reversed for the CF2 radical density. Dilution of the source gases with O2 caused increases in the F atom density and decreases in the CF2 density, but dilution with H2 brought about significant decreases in the F atom density. The density of CF2 radicals was largely affected by the chamber wall conditions, with or without polymer deposition. The decay time constants of these species were also measured during the pulsed afterglow, and the results were qualitatively consistent with the behavior of the densities. However, some quantitative disagreements remain, suggesting that the loss rates of these species in active plasmas are different from the rates in the afterglow.

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

    SciTech Connect

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

    1995-04-24

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

  18. Calculations of the relative free energies of aqueous solvation of several fluorocarbons: A test of the bond potential of mean force correction

    NASA Astrophysics Data System (ADS)

    Gough, Craig A.; Pearlman, David A.; Kollman, Peter

    1993-12-01

    The relative free energies of aqueous solvation of several fluorinated derivatives of methane were calculated using the free energy perturbation (FEP) method. The calculations in general duplicated the experimental free energies with relatively good accuracy, but the calculation of the bond potential of mean force (bond-PMF) contribution [D. A. Pearlman and P. A. Kollman, J. Chem. Phys. 94, 4532 (1991)] was necessary in order to get the most satisfactory agreement with experiment. In particular, it was necessary to use this contribution to obtain even qualitatively correct results for the relative free energies of hydration of methane and tetrafluoromethane. The reasons for this are discussed in terms of the accurate calculation of the effect of the size of the solute. In addition, it is noted that the bond-PMF contribution is important even for FEP calculations not involving large changes in size, such as the ethanol to ethane perturbation, if the length of a bond to a disappearing atom is changed during the perturbation. The relative free energy of aqueous solvation for ethanol and ethane was calculated to demonstrate that if the bond between the oxygen and the hydroxyl hydrogen being removed is ``shrunken'' during the perturbation without including the bond-PMF correction, the calculated free energy is too low by ˜3 kcal/mol.

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

    NASA Astrophysics Data System (ADS)

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

    The anisotropic hyperfine coupling constants (AHCC) from the electron spin resonance (E.S.R.) spectra of a variety of atoms in organic radicals have been calculated by means of semiempirical molecular orbital wavefunctions in the INDO approximation. Hyperfine tensors involving 1H, 13C and 19F nuclei are obtained for the ?H, ?H3, CH3?H2, (CH3)3? hydrocarbon radicals, malonic acid radical, ?H2F, ?F2H, ?F3 and CF3?H2 radicals. The calculated values are compared with available experimental, non-empirical and semiempirical values for these radicals. All integrals of the operator entering the electronic contributions have been evaluated over Slater type orbitals. The introduction of deorthogonalized wavefunctions gives generally better calculated results. In particular, the tensor components of the 19F AHCC are in good agreement with the experimental results without the necessity of readjusting the effective nuclear charges.

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

    Microsoft Academic Search

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

    1981-01-01

    The anisotropic hyperfine coupling constants (AHCC) from the electron spin resonance (E.S.R.) spectra of a variety of atoms in organic radicals have been calculated by means of semiempirical molecular orbital wavefunctions in the INDO approximation. Hyperfine tensors involving 1H, 13C and 19F nuclei are obtained for the CH, CH3, CH3CH2, (CH3)3C hydrocarbon radicals, malonic acid radical, CH2F, CF2H, CF3 and

  1. 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)

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

    1989-01-01

    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.

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

    SciTech Connect

    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

    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.

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

    NASA Astrophysics Data System (ADS)

    Loong, Sang Y.; Lee, H. P.; Chan, Lap Hung; Zhou, Mei-Sheng; Loh, F. C.; Tan, K. L.

    1997-08-01

    In this paper, the polymer composition generated by three different combinations of gas chemistries for oxide etch are studied and the effects of different O2 plasma strip duration on polymer removal are also presented. The etch chemistries used were CHF3/CF4, CO/CF4/CHF3 and C4F8/CO/CHF3 chemistry. From the x-ray photoelectron spectroscopy (XPS) C 1s spectra, five distinct peaks are identified which correspond to C-C, C-CFx, CF, CF2, and CF3. The C/F ratio is found to be highest for polymer generated by the C4F8/CO/CHF3 chemistry, about 0.8, whereas the C/F ratios for those by CHF3/CF4 and CO/CF4/CHF3 chemistries are about 0.6. Atomic force microscopy (AFM) images show that the polymer generated by the C4F8/CO/CHF3 chemistry is much rougher than that by CHF3/CF4 and CO/CF4/CHF3 chemistries. The XPS spectra of C 1s also show a significant decrease in the intensity of the more fluorinated carbon peaks (CF3 and CF2) after O2 plasma strip. The C/F ratios increased to about 1.4 to 1.8 after O2 plasma strip. The spectra are similar for different O2 strip times, indicating the decrease is independent of O2 strip duration. From the AFM images, all the polymers formed by CHF3/CF4 and CO/CF4/CHF3 chemistries are rather smooth with no visible change after O2 strip. However, the polymers generated by C4F8/CO/CHF3 chemistry are flattened with increasing O2 strip duration. The high energy ion bombardment of oxygen ions probably have flattened the rough polymer surface.

  4. Fluorocarbon waste plasma destruction with a high temperature spouted-bed reactor: Kinetics, GC/MS analysis, chemical and mass balance for CF{sub 4}/H{sub 2}/O{sub 2}CaO systems

    SciTech Connect

    Al Ayoubi, S.; Amouroux, J. [ENSCP, Paris (France). Laboratoire de Genie des Procedes Plasmas; Renou-Gonnord, M.F. [Ecole Polytechnique, Palaiseau (France). Laboratoire des Mecanismes Reactionnels

    1995-12-31

    The design of a plasma process for removing organic and hazardous substances has to account for pollutant emission by effluent gases. In order to evaluate the feasibility of using a plasma spouted-bed reactor for waste destruction, an efficient analytical procedure has been developed. CF{sub 4} has been chosen as a model molecule in both experimental work and in kinetic calculations.

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

    Microsoft Academic Search

    Avram Bar-Cohen; Mehmet Arik; Michael Ohadi

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

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

    Microsoft Academic Search

    Douglas M. Robinson; Eckhard A. Groll

    1998-01-01

    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

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

    NASA Technical Reports Server (NTRS)

    Gillman, H. D.

    1980-01-01

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

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

    Microsoft Academic Search

    Leland C. Clark Jr.; Frank Gollan

    1966-01-01

    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,

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

    DOEpatents

    Taylor, G.W.

    1981-01-27

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

  10. Synthesis of Surface-Active Quaternary Amino Polyfluorosiloxanes

    E-print Network

    Chaudhury, Manoj K.

    , on further reaction with various amines followed by quaternization, gave quaternary amino polyfluorosiloxanes prepared by quaternization of fluorocarbon amines using alkyl halide. Quaternary fluorocarbon7 (CF3)2CF(CF2Synthesis of Surface-Active Quaternary Amino Polyfluorosiloxanes ASHISH VAIDYA, MANOJ CHAUDHURY

  11. Refrigeration and Air-Conditioning Technology Workshop

    Microsoft Academic Search

    P. J. Lewis; D. M. Counce

    1993-01-01

    The Alternative Fluorocarbon Environmental Acceptability Study (AFEAS), a consortium of fluorocarbon manufacturers, and the U.S. Department of Energy (DOE) are collaborating on a project to evaluate the energy use and global warming impacts of CFC alternatives. The goal of this project is to identify technologies that could replace the use of CFC's in refrigeration, heating, and air-conditioning equipment; to evaluate

  12. Utilization of oxygen difluoride for syntheses of fluoropolymers

    NASA Technical Reports Server (NTRS)

    Toy, M. S. (inventor)

    1976-01-01

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

  13. Thermally resistant polymers for fuel tank sealants

    NASA Technical Reports Server (NTRS)

    Webster, J. A.

    1972-01-01

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

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

    PubMed Central

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

    2015-01-01

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

  15. All-electric gas detector

    NASA Technical Reports Server (NTRS)

    Margolis, J. S.

    1979-01-01

    Modified optoacoustic gas detector identifies gases by measuring pressure-induced voltage charge in electric signals. Can detect water vapor, atmospheric fluorocarbons, or certain nitrous or nitric compounds that indicate presence of explosives.

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

    SciTech Connect

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

    1981-10-01

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

  17. Amorphous microcellular polytetrafluoroethylene foam film

    NASA Astrophysics Data System (ADS)

    Tang, Chongzheng

    1991-11-01

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

  18. 614 IEEE TRANSACTIONS ON DEVICE AND MATERIALS RELIABILITY, VOL. 4, NO. 4, DECEMBER 2004 Spray Cooling Using Multiple Nozzles: Visualization

    E-print Network

    Kim, Jungho

    -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

  19. Condensing Heat Exchangers Optimize Steam Boilers 

    E-print Network

    Sullivan, B.; Sullivan, P. A.

    1983-01-01

    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...

  20. Long-lasting solid-polymer electrolytic hygrometer

    NASA Technical Reports Server (NTRS)

    Lawson, D. D.

    1978-01-01

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

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

    E-print Network

    Rasgon, Stacy A., 1974-

    2005-01-01

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

  2. 46 CFR 128.410 - Ship's service refrigeration systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...refrigeration systems. No self-contained unit either for air-conditioning or for refrigerated spaces for ship's stores need...chapter if— (a) The unit uses a fluorocarbon refrigerant allowed by part 147 of this chapter; (b)...

  3. 46 CFR 128.410 - Ship's service refrigeration systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...refrigeration systems. No self-contained unit either for air-conditioning or for refrigerated spaces for ship's stores need...chapter if— (a) The unit uses a fluorocarbon refrigerant allowed by part 147 of this chapter; (b)...

  4. 46 CFR 128.410 - Ship's service refrigeration systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...refrigeration systems. No self-contained unit either for air-conditioning or for refrigerated spaces for ship's stores need...chapter if— (a) The unit uses a fluorocarbon refrigerant allowed by part 147 of this chapter; (b)...

  5. Cardiovascular disease and environmental exposure

    Microsoft Academic Search

    K D Rosenman

    1979-01-01

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

  6. Transparent fluids for 157-nm immersion lithography

    E-print Network

    Rollins, Andrew M.

    Lawrence, Massachusetts 01843 Abstract. More than 50 fluorocarbon liquids are measured for transpar- ency for use in 157-nm liquid immersion lithography. Purification methods such as degasification, distillation resonance spectroscopy (for molecular structure), gel permeation chromatography (for molecular weight), Karl

  7. The use of cavitation for the production of diver breathing gas 

    E-print Network

    Klentzman, Chris Adam

    1990-01-01

    . Fluorocarbon breathing ', was applied to biomedical research where the dangers of decompression sickness could be more safely avoided hy breathing a liquid instead of a gas. It was demonstrated by ' Kylstra et al. that fluorocarbon-breathing mice could... be 11 rapidly decompressed without fatal decompression sickness applications in biomedical research, it is essentially im- 6 (33 atmospheres in 5 seconds). While liquid breathing has practical for open water use. The amount of equipment necessary...

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

    PubMed Central

    Jee, Jun-Pil; McCoy, Aaron; Mecozzi, Sandro

    2011-01-01

    Purpose PEG-phospholipid-based micelles have been successfully used for the solubilization of several hydrophobic drugs but generally lack sustained stability in blood. Our novel PEG-Fluorocarbon-DSPE polymers were designed to increase stability and improve time-release properties of drug-loaded micelles. Methods Novel ABC fluorous copolymers were synthesized, characterized, and used for encapsulation release of amphotericin B. FRET studies were used to study micelle stability. Results The micelles formed by the new polymers showed lower critical micelle concentrations and higher viscosity cores compared with those formed by the polymers lacking the fluorous block. FRET studies indicated that fluorocarbon-containing micelles had increased stability in the presence of human serum. Physicochemical properties and in vitro release profile of the micelles loaded with Amphotericin B (AmB) were studied. Conclusions The effect of PEG length and fluorocarbon incorporation were investigated. The shorter hydrophilic PEG-2K induced greater stability than PEG-5K by decreasing the proportion of hydrophilic block of the polymer. The fluorocarbon placed between hydrophilic and hydrophobic block formed a fluorous shell contributing to the enhanced thermodynamic stability of micelles and to the drug sustained release. Polymer mPEG2K-F10-DSPE, bearing both a fluorocarbon block and a shorter mPEG, showed the greatest stability and the longest half-life for AmB release. PMID:21739321

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

    SciTech Connect

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

    2000-02-02

    The objective of this study was to design, synthesize, and characterize thickening agents for dense carbon dioxide and to evaluate their solubility and viscosity-enhancing potential in CO{sub 2}. Hydrocarbon-fluorocarbon random copolymers, 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%.

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

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

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

  11. Fiber optic plenum cable

    NASA Astrophysics Data System (ADS)

    Angeles, Purita; Kurt, Jeffrey

    1986-11-01

    Fiber optic plenum cables use fluorocarbon jackets to provide the low smoke and flame characteristics required to be classified as plenum cables. Compared with more commonly used optical cable jackets, fluorocarbon jackets have less creep resistance and potentially higher shrinkback. Consequently, the establishment of satisfactory plenum cables required both specialized modeling and experimental cable testing. This paper describes theoretical modelling of the change in attenuation of a plenum fiber optic cable as a function of temperature range. The temperature test results of one and two fiber plenum cables and single fiber connectorized assemblies show the models to be useful tools in rationally developing fiber optic plenum cable.

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

    PubMed Central

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

    2008-01-01

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

  13. Potential Energy Savings by Using Alternative Technologies for the Separation of Fluid Mixtures

    E-print Network

    Bravo, J. L.

    -liquid extraction for the separation of ethanol and water. a liquid extraction step where a fluorocarbon sol vent [6,7] is put in contact with the ethanol-water stream. The fluorocarbon-ethanol mixture is distilled and the ethanol is recovered at the bottom... at this time: extractive distillation with gasoline [2J, liquid extraction with gasoline [12J, and ethanol adsorption followed by gasoline extraction [2J. These schemes range in energy consumption from about 5,000 Btu/gallon for the adsorption...

  14. Cardiovascular disease and environmental exposure.

    PubMed Central

    Rosenman, K D

    1979-01-01

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

  15. Superhydrophobic engineering surfaces with tunable air-trapping ability

    Microsoft Academic Search

    Yilei Zhang; Sriram Sundararajan

    2008-01-01

    A versatile hybrid processing method that combines electrostatic deposition of microparticles and subsequent anisotropic plasma etching is described that can generate superhydrophobic engineering surfaces with tunable bimodal roughness and a thin hydrophobic fluorocarbon film. These surfaces exhibit contact angles with water of more than 160° for particle coverage beyond a threshold value. A geometric model based on air-trapping ability is

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

    EPA Science Inventory

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

  17. Modelling of morphology and proton transport in PFSA membranes

    Microsoft Academic Search

    James A. Elliotta; Stephen J. Paddison

    2007-01-01

    Computational modelling studies of the structure of perfluorosulfonic acid (PFSA) ionomer membranes consistently exhibit a nanoscopic phase-separated morphology in which the ionic side chains and aqueous counterions segregate from the fluorocarbon backbone to form clusters or channels. Although these investigations do not unambiguously predict the size or shape of the clusters, and whether or not the channels percolate the matrix

  18. Superior performance of multilayered fluoropolymer films in low voltage electrowetting

    Microsoft Academic Search

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

    The requirement for low operational voltage in electrowetting devices, met using thin dielectrics, is usually connected with serious material failure issues. Dielectric breakdown (visible as electrolysis) is frequently evident slightly beyond the onset of the contact angle saturation. Here, plasma-enhanced chemical vapor deposition (PECVD) is used to deposit thin fluorocarbon films prior to the spin-coating of Teflon® amorphous fluoropolymer on

  19. Superior performance of multilayered fluoropolymer films in low voltage electrowetting

    Microsoft Academic Search

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

    2011-01-01

    The requirement for low operational voltage in electrowetting devices, met using thin dielectrics, is usually connected with serious material failure issues. Dielectric breakdown (visible as electrolysis) is frequently evident slightly beyond the onset of the contact angle saturation. Here, plasma enhanced chemical vapor deposition (PECVD) is used to deposit thin fluorocarbon films prior to the spin-coating of Teflon\\\\textregistered amorphous fluoropolymer

  20. Fabrication of robust hollow waveguide devices for Er:YAG laser light

    Microsoft Academic Search

    You Wang; Hajime Hiraga; Yuji Matsuura; Mitsunobu Miyagi

    1997-01-01

    We report transmission properties of two kinds of robust bent hollow stainless steel (St) waveguides whose inner surface is coated by the thin silver (Ag) and fluorocarbon- polymer (FCP) layers. The bore size of the waveguides is 700 micrometer and all types of waveguides have been fabricated based on the liquid phase process, i.e., the process of silver mirror reaction

  1. Perfluoroalkyl Nitroso Compounds

    Microsoft Academic Search

    Joan Banus

    1953-01-01

    A PRELIMINARY study1 of the photochemical properties of the first fluorocarbon iodide, trifluoro-iodomethane, showed that a trifluoromethyl radical is produced the primary reactions of which parallel those of the hydrocarbon free radicals. A direct method thus became available for the preparation of perfluoroalkyl nitroso compounds, by irradiation of the iodide in the presence of nitric oxide and of mercury (to

  2. Open Archive Toulouse Archive Ouverte (OATAO) OATAO is an open access repository that collects the work of Toulouse researchers and

    E-print Network

    Boyer, Edmond

    Chemistry SB RAS, pr. Ak. LaVrentieVa 3, NoVosibirsk 630090, Russian Federation, BoreskoV Institute of Catalysis SB RAS, pr. Ak. LaVrentieVa 5, NoVosibirsk 630090, Russian Federation, and CIRIMAT, UMR CNRS 5085 has showed that the fluorine is driven off the tubes in the form of various fluorocarbon species.5

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

    Microsoft Academic Search

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

    2001-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Ross, B.

    1981-01-01

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

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

    PubMed

    Schvartzman, M; Wind, S J

    2009-04-01

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

  6. Metal Surface Decontamination by the PFC Solution

    Microsoft Academic Search

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

    2006-01-01

    PFC (per-fluorocarbon) spray decontamination equipment was fabricated and its decontamination behavior was investigated. Europium oxide powder was mixed with the isotope solution which contains Co-60 and Cs-137. The different shape of metal specimens artificially contaminated with europium oxide powder was used as the surrogate contaminants. Before and after the application of the PFC spray decontamination method, the radioactivity of the

  7. Adsorption of Hydrofluorocarbons HFC-134 and HFC-134A on X and Y Zeolites: Effect of Ion-Exchange on Selectivity and Heat of Adsorption

    E-print Network

    Siperstein, Flor R.

    rapidly as worldwide refrigerator and air-conditioner production rises almost exponentially.1 A byproduct. Gorte, Alan L. Myers,* Clare P. Grey, and David R. Corbin Department of Chemical Engineering, Uni) is a hydrofluorocarbon coolant for refrigerators designated to replace the ozone-damaging chloro- fluorocarbons (CFCs

  8. Water-based intumescent paint

    NASA Technical Reports Server (NTRS)

    Sauers, D. G.; Nannelli, P.

    1979-01-01

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

  9. Enhanced Particle Removal in Fluorinated Liquids—An Application in Nuclear Decontamination

    Microsoft Academic Search

    C. S. Yam; O. K. Harling; R. Kaiser

    1997-01-01

    An experimental cleaning system has been developed to demonstrate the decontamination of model electronic circuit boards by this cleaning process. The media used in this process are a wash solution of a high molecular weight fluorocarbon surfactant in a perfluorinated carrier liquid which results in enhanced particle removal, followed by a perfluorinated carrier liquid rinse. The perfluorinated liquids of interest,

  10. Evaluation of Plasma-Deposited Hydrophobic Coatings on Pigment-Coated Paper for Reduced Dampening Water Absorption

    Microsoft Academic Search

    M. Pykönen; K. Johansson; M. Dubreuil; D. Vangeneugden; G. Ström; P. Fardim; M. Toivakka

    2010-01-01

    Hydrophobic plasma coatings were deposited on pigment-coated paper with the purpose of reducing dampening water absorption and create uniform surface chemistry. The influence of plasma coatings on sheet-fed offset printability was also studied. Three plasma chemistries, fluorocarbon, organosilicon and hydrocarbon, were used to adjust the hydrophobicity of paper surface. The plasma coatings reduced, and in some cases prevented, the dampening

  11. Gas mixtures for spark gap closing switches

    DOEpatents

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

    1987-02-20

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

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

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

  13. Organofluorine chemistry: A Janus cyclohexane ring

    NASA Astrophysics Data System (ADS)

    Santschi, Nico; Gilmour, Ryan

    2015-06-01

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

  14. 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...

  15. The Great Spray Can Debate.

    ERIC Educational Resources Information Center

    Bassow, Herb

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

  16. Role of extrinsic factors in utilizing the giant magnetocaloric effect on materials: Frequency and time dependence

    Microsoft Academic Search

    Sesha Chalapathi Madireddi

    2010-01-01

    Magnetic refrigeration (MR) is potentially a high efficiency, low cost, and greenhouse gas-free refrigeration technology, and with the looming phase out of HCFC and HFC fluorocarbons refrigerants is drawing more attention as an alternative to the existing vapor compression refrigeration. MR is based on the magnetocaloric effect (MCE), which occurs due to the coupling of a magnetic sublattice with an

  17. Black silicon method XI: oxygen pulses in SF6 plasma

    Microsoft Academic Search

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

    2010-01-01

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

  18. Greenhouse effect of chlorofluorocarbons and other trace gases

    Microsoft Academic Search

    James Hansen; Andrew Lacis; Michael Prather

    1989-01-01

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

  19. Effects of Simulated Nuclear Thermal Pulses on Fiber Optic Cables

    Microsoft Academic Search

    A. J. Baba; S. Share; J. H. Wasilik

    1979-01-01

    The effects of pulsed thermal radiation on fiber optic cables with a variety of jackets (polyurethane, PVC, fluorocarbon) are presented. Exposure between 27 and 85 cal\\/cm2 did not sever the optical fibers, but the radiation did cause disintegration of the jackets and the Kevlar strength members, which resulted in a significant reduction of the cable's ability to survive mechanical stress.

  20. Effects of dissolved gases on subcooled flow boiling from small heated regions with and without streamwise concave curvature

    Microsoft Academic Search

    P. S. Wu; T. W. Simon

    1994-01-01

    Coolants such as fluorocarbon liquids usually contain high levels of dissolved gases. When heated, these gases are liberated from the liquid; if the liquid is boiling, these gases may influence the supply of liquid to the boiling surface. In this study, the effects of dissolved air in perfluorinated hydrocarbon, FC-72, on flow boiling heat transfer characteristics were experimentally investigated over

  1. Prediction of the Pool Boiling Critical Heat Flux Using Artificial Neural Network

    Microsoft Academic Search

    H. Metin Ertunc

    2006-01-01

    This study deals with artificial neural network (ANN) based prediction of the pool boiling critical heat flux (CHF) for dielectric liquids under a variety of operating conditions. For this purpose, first, the effects of pressure and subcooling of the fluid on nucleate pool boiling and CHF on the surface of an integrated circuit (IC) immersed in a fluorocarbon FC-72 liquid

  2. Enhancement of a two-phase thermosyphon for cooling high heat flux power devices

    Microsoft Academic Search

    Heikichi Kuwahara; Kenji Takahashi; Tadakatsu Nakajima; Toshio Takasaki; S. O. Suzuki

    1995-01-01

    The purpose of this study is the enhancement of cooling of high heat flux power devices such as a thyristor by a thermosyphon system. The thermosyphon uses boiling and condensation of an inert dielectric fluorocarbon (FC-72). Boiling occurs from a multiple chimney heat transfer structure. A boiling chamber is connected to the condenser by a double tube, with the inner

  3. Enhancement of two-phase thermosyphon for cooling high heat flux power devices

    Microsoft Academic Search

    Heikichi Kuwahara; Kenji Takahashi; Tadakatsu Nakajima; Osamu Suzuki; Toshio Takasaki

    1994-01-01

    The purpose of this study is the enhancement of cooling of high heat flux power devices such as a thyristor by a thermosyphon system. The thermosyphon used boiling and condensation of inert dielectric fluorocarbon (FC-72). Boiling occurred from a multiple chimney heat transfer structure. A boiling chamber is connected to the condenser by a double tube, with the inner tube

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

    NASA Astrophysics Data System (ADS)

    Ross, B.

    1981-09-01

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

  5. Fast-drying coating

    NASA Technical Reports Server (NTRS)

    Bartoszek, E. J.

    1978-01-01

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

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

    Microsoft Academic Search

    B. Ross; J. Parker

    1983-01-01

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

  7. Development of an all-metal thick-film cost-effective metallization system for solar cells. Quarterly report No. 3, November 1980April 1981

    Microsoft Academic Search

    1981-01-01

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

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

    PubMed Central

    Schvartzman, M.; Wind, S. J.

    2009-01-01

    Diamond-like carbon (DLC) films, used as molds for nanoimprint lithography, were treated with a fluorocarbon-based plasma in order to enhance their anti-adhesion properties. While 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

  9. 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

  10. J. Physiol. (I959) I47, 226-238 SINGLE UNIT ACTIVITY IN STRIATE CORTEX OF

    E-print Network

    Hubel, David

    Reed Army Medical Center, Washington 12, D.C., U.S.A. (Received 15 December 1958) A beginning has of recording (Text-fig. 1). The peg was made of the plastic Kel-F (fluorocarbon polymer made by Minnesota Mining and Manufacturing Company, St Paul, Minn.). It was hollow and was * Present addreas

  11. Western Nanofabrication Facility Mohammadali Tabatabaei, Ph.D. candidate, supervisor: Prof. Franois Lagugn-Labarthet

    E-print Network

    Lennard, William N.

    group has allowed one to prepare such pristine surfaces using devices designed by fabricating during a synapse event. It is noteworthy that all the instruments required for the fabrication. Surface Modi3ication by Fluorocarbon Plasma Deposition for Controlled Cell Growth

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

    NASA Technical Reports Server (NTRS)

    McKinnon, Thomas; Todd, Paul; Oberdorster, Gunter

    1996-01-01

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

  13. 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...

  14. Manifold microchannel heat sinks: isothermal analysis

    Microsoft Academic Search

    D. Copeland; M. Behnia; W. Nakayama

    1996-01-01

    Numerical analyses of manifold microchannel (MMC) heat sinks were performed. The MMC differs from a traditional microchannel heat sink in that the flow length is greatly reduced to a small fraction of the total length of the heat sink. Alternating inlet and outlet channels guide the coolant to and from the microchannels. A silicon heat sink cooled by fluorocarbon liquid

  15. Manifold microchannel heat sinks: isothermal analysis

    Microsoft Academic Search

    David Copeland; Masud Behnia; Wataru Nakayama

    1997-01-01

    Numerical analyses of manifold microchannel (MMC) heat sinks were performed. The MMC differs from a traditional microchannel heat sink in that the how length is greatly reduced to a small fraction of the total length of the heat sink. Alternating inlet and outlet channels guide the coolant to and from the microchannels. A silicon heat sink cooled by fluorocarbon liquid

  16. Gas mixtures for spark gap closing switches

    DOEpatents

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

    1988-01-01

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

  17. Thermal battery

    SciTech Connect

    Williams, M.T.; Winchester, C.S.; Jolson, J.D.

    1989-06-20

    A thermal battery is described comprising at least one electrochemical cell comprising an anode of alkali metal, alkaline earth metal or alloys thereof, a fusible salt electrolyte, a fluorocarbon polymer or fluorochlorocarbon polymer depolarizer, and means for heating the cell to melt the electrolyte.

  18. Thermal design space prediction in direct liquid cooling

    Microsoft Academic Search

    T. Y. Tom Lee; Mali Mahalingam

    1991-01-01

    A software for predicting the optimum operating conditions for a two-phase liquid cooling environment is presented. This software consists of a data bank which includes a variety of physical and thermodynamic properties of fluorocarbons and includes heat transfer correlations which cover single-phase, boiling incipience, nucleate boiling, and critical heat flux. The heat flux of the integrated circuit is compared to

  19. Thermal design space prediction in two-phase direct liquid cooling

    Microsoft Academic Search

    T. Y. T. Lee; M. Mahalingam

    1992-01-01

    Software for predicting the optimum operating conditions for a two-phase liquid cooling environment is presented. This software consists of a data bank which includes a variety of physical and thermodynamic properties of fluorocarbons. It also includes heat transfer correlations which cover the range from single-phase boiling incipience, to nucleate boiling, to critical heat flux. The heat flux of the integrated

  20. Polyphosphazene Icephobic Coating Materials

    NASA Technical Reports Server (NTRS)

    Willis, Paul B.

    1992-01-01

    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.

  1. Supramolecular Polymers Formed by ABC Miktoarm Star Peptides

    PubMed Central

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

    2014-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Wheeler, Donald R.; Pepper, Stephen V.

    1990-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Wheeler, Donald R.; Pepper, Stephen V.

    1990-01-01

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

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

    SciTech Connect

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

    2000-02-02

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

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

    NASA Technical Reports Server (NTRS)

    1990-01-01

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

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

    PubMed

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

    2015-03-16

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

  7. Modeling of inductively coupled CHF_3/Ar plasma mixture

    NASA Astrophysics Data System (ADS)

    Bose, Deepak; Govindan, T. R.; Meyyappan, M.

    2002-10-01

    Fluorocarbon plasmas are used widely for etching of silicon dioxide and other silicon compounds. Most modeling studies of fluorocarbon discharges in the literature have focused on CF4 discharges. Modeling of CHF3 plasmas in the literature is limited due to significant uncertainties in the reaction mechanism leading to dissociation and ionization into a large array of neutral radicals and ions. Only a small fraction of these possible reaction steps have been characterized experimentally or via ab initio studies. In this work we will present 2d ICP modeling results at low pressures (10-50 mTorr) based on currently available data. In an attempt to reduce some of the uncertainty in the reaction mechanism, we will compare the modeling results with available mass spectrometric and langmuir probe data in the literature. Apart from bulk plasma properties, we will compare relative ion fluxes into the wafer in order to assess the validity of predicted radical and ion concentrations in the discharge.

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

    NASA Astrophysics Data System (ADS)

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

    2011-08-01

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

  9. Heat transfer from grooved surfaces to flow of fluorinert coolant in reduced-size channels

    Microsoft Academic Search

    Hitoshi Mizunuma; Masud Behnia; Wataru Nakayama

    1996-01-01

    Experiments were conducted in order to investigate the forced convective heat transfer from a grooved surface to a fluorocarbon liquid FX3250. The heat transfer surface is made from copper, has a base area 2×2 cm2, and is equipped with 20 longitudinal fins, each fin being 0.5 mm high and 0.5 mm wide. A particular attention was directed to the effect

  10. Heat transfer from micro-finned surfaces to flow of fluorinert coolant in reduced-size channels

    Microsoft Academic Search

    Hitoshi Mizunuma; Masud Behnia; Wataru Nakayama

    1997-01-01

    Experiments were conducted in order to investigate the forced convective heat transfer from a micro-finned surface to a fluorocarbon liquid FX3250. The heat transfer surface is made from copper, has a base area 2×2 cm2, and is equipped with 20 longitudinal fins, each fin being 0.5 mm high and 0.5 mm wide. Particular attention was directed to the effect of

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

    SciTech Connect

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

    1995-12-31

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

  12. Robust hollow devices and waveguides for Er:YAG laser radiation

    Microsoft Academic Search

    Y. Wang; Y. Matsuura; M. Miyagi

    1998-01-01

    Fluorocarbon-polymer (FCP) coated silver hollow stainless steel (St) devices and waveguides have been developed for Er:YAG laser radiation. Full liquid phase techniques have been adopted to coat the silver and FCP layers inside the stainless steel hollow structure. Both straight and bent robust hollow devices have been fabricated as the output optical elements for the delivery system of medical Er:YAG

  13. HWCVD of polymers: Commercialization and scale-up

    Microsoft Academic Search

    Hilton G. Pryce Lewis; Neeta P. Bansal; Aleksandr J. White; Erik S. Handy

    2009-01-01

    GVD Corporation specializes in process development and equipment design for the production of ultra-thin polymer coatings using hot wire chemical vapor deposition (HWCVD, also known as initiated chemical vapor deposition, iCVD). HWCVD allows many coating compositions to be produced, including fluorocarbon and silicone polymers, copolymers, and vinyl hydrocarbon polymers. It is especially valuable for creating ultra-thin layers of insoluble, infusible

  14. Mitigating molecular and particulate contamination via surface energy

    Microsoft Academic Search

    Mark S. Crowder; Christina Haley

    2008-01-01

    Amorphous fluorocarbon (a-C:F) thin films have been developed that protect surfaces from molecular and particulate contamination. The surface energies of the thin films are low and primarily dispersive in origin with values of energies measured to be as low as 18 mJ\\/m2 (17.5 dispersive, 0.5 polar). The films are transparent to visible light and have a refractive index of ~1.4.

  15. Synthesis and solution properties of cholesterol end-capped poly(ethylene glycol)

    Microsoft Academic Search

    Ning Yao; Alex M. Jamieson

    2000-01-01

    A series of cholesterol end-capped poly(ethylene glycol) (Ch2PEG) were synthesized by coupling cholesterol at each end of PEG (molecularweight=4000, 10?000, 20?000 and 35?000g\\/mol) with hexamethylene diisocyanate. Unlike hydrophobically modified PEGs, which are end-capped with flexible hydrocarbons or fluorocarbons, Ch2PEGs are not soluble in water, although they do swell significantly, and the swelling ratio increases with molecular weight. Analysis of the

  16. Fluorspar

    USGS Publications Warehouse

    Miller, M.

    1996-01-01

    The U.S. consumed about 525 kt of fluorspar in 1995, with more than 70 percent being used for the production of hydrofluoric acid. Fluorspar is also used for the production of aluminum and steel. About 558 kt of fluorspar was imported in 1995, with a further 186 kt made available from the National Defense Stockpile. The market in the U.S. is expected to grow as increasing use is made of fluorocarbons to replace chlorofluorocarbons.

  17. Fabrication and tribological properties of super-hydrophobic surfaces based on porous silicon

    Microsoft Academic Search

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

    2009-01-01

    In the present work, super-hydrophobic surfaces based on porous silicon (PS) were constructed by the self-assembled molecular films and their tribological properties were investigated. A simple chemical etching approach was developed to fabricate PS with the certain rough microstructure surface, which can be observed by the environmental scanning electron microscopy (ESEM). The hydrocarbon and fluorocarbon alkylsilane molecular films were self-assembled

  18. Single-phase and boiling cooling of small pin fin arrays by multiple slot nozzle suction and impingement

    Microsoft Academic Search

    David Copeland

    1994-01-01

    Experimental measurements of forced convection single-phase and boiling heat transfer from pin fin arrays were made using fluorocarbon liquid FC-72. Liquid flow was directed to and from the pin fin arrays by multiple slot nozzles, alternately providing suction and impingement flow. Rectangular pin fin arrays having equal width and spacing of 0.1 and 0.2 mm and aspect ratios of 1,

  19. International research into chlorofluorocarbon (CFC) alternatives

    SciTech Connect

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

    1992-05-01

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

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

    Microsoft Academic Search

    Xiuling Zhu; Yuxiu Liu; Lei Zhu

    2009-01-01

    \\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,

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

    NASA Technical Reports Server (NTRS)

    Gillman, H. D.; Nannelli, P.

    1979-01-01

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

  2. Experimental observations of hydrate formation in a convection tank

    Microsoft Academic Search

    C. F. Chen; Cho Lik Chan

    2003-01-01

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

  3. 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

    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

    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

  4. Evisceration implant of Proplast II. A preliminary report.

    PubMed

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

    1990-01-01

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

  5. Needs of thermodynamic properties measurements and modeling in the frame of new regulations on refrigerants

    Microsoft Academic Search

    Christophe Coquelet; Dominique Richon

    2007-01-01

    In 1987, the Montreal Protocol prohibited the worldwide use and production of chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons\\u000a (HCFCs) and hydro fluorocarbons (HFCs) were proposed as alternative refrigerants. Unfortunately, HFCs have non negligible\\u000a global warning potential and therefore new refrigerants must be proposed or old refrigerants must be used associated with\\u000a HFC. Accurate experimental thermodynamic data and predictive techniques are required for

  6. New textile composite materials development, production, application

    NASA Technical Reports Server (NTRS)

    Mikhailov, Petr Y.

    1993-01-01

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

  7. Uptake of trifluoroacetate by Pinus ponderosa via atmospheric pathway

    NASA Astrophysics Data System (ADS)

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

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

  8. Greenhouse effect of chlorofluorocarbons and other trace gases

    NASA Technical Reports Server (NTRS)

    Hansen, James; Lacis, Andrew; Prather, Michael

    1989-01-01

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

  9. Biotransformation of 2,3,3,3-tetrafluoropropene (HFO1234yf) in rabbits

    Microsoft Academic Search

    Paul Schuster; Ruediger Bertermann; Georg M. Rusch; Wolfgang Dekant

    2010-01-01

    2,3,3,3-Tetrafluoropropene (HFO-1234yf) is a non-ozone-depleting fluorocarbon replacement with a low global warming potential and is developed as refrigerant. Due to lethality observed after high concentration inhalation exposures of HFO-1234yf in a developmental toxicity study with rabbits, the biotransformation of HFO-1234yf was investigated in this species. Female New Zealand White rabbits were exposed to air containing 2000; 10,000; or 50,000 ppm (n=3\\/concentration)

  10. Improvement in hydrophobicity of polyester fabric finished with fluorochemicals via aminolysis and comparing with nano-silica particles

    Microsoft Academic Search

    Zahra Mazrouei-Sebdani; Akbar Khoddami; Shadpour Mallakpour

    2011-01-01

    For the fabrication of the “lotus-type” fibers, a combination of two major requirements, low surface energy and the magnified\\u000a of the degree of roughness, should be utilized. In this research, the possible surface roughening effect of aminolysis of\\u000a the polyester fibers was applied to manipulated surface topography while fluorocarbon polymer layer generates low surface\\u000a energy. The results were compared with

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

    NASA Astrophysics Data System (ADS)

    Banik, Indranil; Bhowmick, Anil K.

    2000-05-01

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

  12. Organic Rankine Cycles for the Petro-Chemical Industry

    E-print Network

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

    1979-01-01

    of these fluids due to their flammability, toxicity, availability and/or cost, MTI selected a Binary Rankine cycle based upon the use of steam and a fluorocarbon refrigerant. In addition to overcoming potential market resistance, the Binary Rankine cycle offered... a number of advantages to MIl and the government. When MTI made a commitment to develop Rankine bottoming cycles in 1974, it was not clear what shape or form the market would ultimately take. The Binary Rankine cycle satisfied an identified market...

  13. Comparative Investigation of Several Sperm Analysis Methods for Evaluation of Spermatotoxicity of Industrial Chemical: 2-Bromopropane as an Example

    Microsoft Academic Search

    Katsumi OHTANI; Shigeru YAMAZAKI; Hisayo KUBOTA; Muneyuki MIYAGAWA; Junzo SAEGUSA

    2004-01-01

    Reproductive toxicity of 2-bromopropane (2BP), a substitute for ozone layer-depleting chloro-fluorocarbon, was found among the workers in an electronics factory in Korea in 1995. Furthermore the importance of testicular toxicity has been realized since the problem of endocrine disruptors arose all over the world, but manual methods must rely on subjective assessment. Recently, computer-assisted sperm analysis (CASA) was proposed but

  14. Conformations of Poly(Methyl Methacrylates) End-Capped with Pentafluorophenyl Groups

    Microsoft Academic Search

    Ekaterina R. Gasilova; Olga G. Zamyshlyayeva; Yury D. Semchikov

    2011-01-01

    The current work deals with the influence of thermodynamic incompatibility of the fluorocarbon end groups and the hydrocarbon main chain on macromolecular conformations of end-capped polymers in solution. Dilute non-aggregated acetone solutions of a set of poly(methyl methacrylates), modified with ?GeH(C6F5)2 and ?Ge(C6F5)3 end groups, were studied with static and dynamic light scattering and viscometry. It was shown that in

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

    Microsoft Academic Search

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

    1993-01-01

    Various papers on the dynamic aspects of detonations are presented. Individual subjects addressed include: high-resolution numerical simulations for 2D unstable detonations, simulation of cellular structure in a detonation wave, Mach reflection of detonation waves, mechanism of unstable detonation front origin, numerical modeling of galloping detonation, experimental study of the fine structure in spin detonation, influence of fluorocarbon on H2O2Ar detonation,

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

    Microsoft Academic Search

    Yasufumi Miyoshi; Masaru Miyauchi; Atsushi Oguni; Toshiaki Makabe

    2004-01-01

    Highly selective SiO2 etch over Si is required to manufacture ULSI devices. Reactive ion etching using polymerizing fluorocarbon chemistries provides the process for selective dry etching of SiO2 over Si. A number of species including electrons, ions, and radicals are generated in the plasma processing by reactions in gas phase and on surface. A large amount of highly reactive fluorine

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

    Microsoft Academic Search

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

    2000-01-01

    We have developed a new process for applying a hydrophobic, low adhesion energy coating to microelectromechanical (MEMS) devices. Monolayer films are synthesized from tridecafluoro-1,1,2,2-tetrahydrooctyltrichlorosilane (FOTS) and water vapor in a low-pressure chemical vapor deposition process at room temperature. Film thickness is self-limiting by virtue of the inability of precursors to stick to the fluorocarbon surface of the film once it

  18. Properties of c-C4F8 inductively coupled plasmas. II. Plasma chemistry and reaction mechanism for modeling of Arc-C4F8 O2 discharges

    E-print Network

    Kushner, Mark

    of these processes for different materials e.g., etching of SiO2 vs Si3N4) have resulted in the use of a wide variety of fluorocarbon gases e.g., CHF3 , C2F6 , and c-C4F8) and numerous additives e.g., O2 , N2 , CO, and Ar , and CO are often used for the plasma etching of silicon dioxide. Gas phase reaction mechanisms

  19. The feasibility study of hot cell decontamination by the PFC spray method

    Microsoft Academic Search

    Hui-Jun Won; Chong-Hun Jung; Jei-Kwon Moon

    2008-01-01

    The characteristics of per-fluorocarbon compounds (PFC) are colorless, non-toxic, easily vaporized and nonflammable. Also, some of them are liquids of a high density, low surface tension, low latent heat and low specific heat. These particular chemical and physical properties of fluoro-organic compounds permit their use in very different fields such as electronics, medicine, tribology, nuclear and material science. The Sonatol

  20. High performance optoelectronic device based on semitransparent organic photovoltaic cell integrated with organic light-emitting diode

    Microsoft Academic Search

    Xi Zu Wang; Hoi Lam Tam; Kian Soon Yong; Zhi-Kuan Chen; Furong Zhu

    2011-01-01

    A high performance organic optoelectronic device that integrates a front semitransparent organic photovoltaic (OPV) cell and a microcavity organic light-emitting diode (MOLED) connected with a 0.3-nm-thick plasma-polymerized fluorocarbon film (CFX)-modified ultra-thin silver interlayer (Ag\\/CFX) has been reported. Through proper selection of the active materials, and optimal design of the device structure, the semitransparent OPV cell in the integrated device achieves

  1. Use of atmospheric pressure plasma to confer durable water repellent functionality and antimicrobial functionality on cotton\\/polyester blend

    Microsoft Academic Search

    Rachel Davis; Ahmed El-Shafei; Peter Hauser

    2011-01-01

    A non-thermal, high density atmospheric plasma glow discharge treatment was used to impart functionality to cotton\\/polyethylene terephthalate (PET) fabric to furnish a surface that is water repellent and then antimicrobial only.In this work, cotton\\/PET (50\\/50%) blend fabric was treated with a water repellent treatment through activating the surface with plasma, depositing a vaporized fluorocarbon based monomers, 1,1,2,2-tetrahydroperfluorodecyl acrylate (THPFDA) and

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  3. The Effect of Column and Eluent Fluorination on the Retention and Separation of non-Fluorinated Amino Acids and Proteins by HPLC.

    PubMed

    Joyner, Katherine; Wang, Weizhen; Yu, Yihua Bruce

    2011-02-01

    The effect of column and eluent fluorination on the retention and separation of non-fluorinated amino acids and proteins in HPLC is investigated. A side-by-side comparison of fluorocarbon column and eluents (F-column and F-eluents) with their hydrocarbon counterparts (H-column and H-eluents) in the separation of a group of 33 analytes, including 30 amino acids and 3 proteins, is conducted. The H-column and the F-column contain the n-C(8)H(17) group and n-C(8)F(17) group, respectively, in their stationary phases. The H-eluents include ethanol (EtOH) and isopropanol (ISP) while the F-eluents include trifluoroethanol (TFE) and hexafluorosopropanol (HFIP). The 2 columns and 4 eluents generated 8 (column, eluent) pairs that produce 264 retention time data points for the 33 analytes. A statistical analysis of the retention time data reveals that although the H-column is better than the F-column in analyte separation and H-eluents are better than F-eluents in analyte retention, the more critical factor is the proper pairing of column with eluent. Among the conditions explored in this project, optimal retention and separation is achieved when the fluorocarbon column is paired with ethanol, even though TFE is the most polar one among the 4 eluents. This result shows fluorocarbon columns have much potential in chromatographic analysis and separation of non-fluorinated amino acids and proteins. PMID:21318121

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

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2002-03-01

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

  6. The aqueous catanionic system sodium perfluorooctanoate-dodecyltrimethylammonium bromide at low concentration.

    PubMed

    López-Fontán, José Luis; Blanco, Elena; Ruso, Juan M; Prieto, Gerardo; Schulz, Pablo C; Sarmiento, Félix

    2007-08-15

    The interaction between sodium perfluorooctanoate (SPFO) and dodecyltrimethylammonium bromide (DTAB) was studied by several methods and it was found strongly synergistic. Above a mole fraction of SPFO in the surfactant mixture (alpha(SPFO))=0.38, the interaction is repulsive and increases with the content of SPFO in both, the overall mixture and micelles, whereas the interaction is attractive if DTAB is in excess. At alpha(SPFO)=0.38 the low miscibility between hydrocarbon and fluorocarbon is counterbalanced by the electrostatic attraction between the opposite charged head groups, and the micelle composition is ideal (i.e., the mole fraction of SPFO in micelles X(SPFO)=alpha(SPFO)=0.38). The solubility of fluorocarbon in hydrocarbon is lower than that of hydrocarbon in fluorocarbon. Micelles of DTAB act as a solvent for SPFO without important structural changes, whilst micelles of SPFO undergo important changes when dissolve DTAB. This asymmetry may be interpreted as caused by the difference in chain length that favors the inclusion of the shorter chain in micelles of the longer surfactant, but disfavors the opposite process. Above X(SPFO)=0.5 there is an excess adsorption of bromide ions on the mixed micelles surface, giving rise to a high zeta potential. Micelles of pure SPFO or pure DTAB show an important energy barrier which prevents micelle flocculation. The inclusion of SPFO in DTAB micelles produces a reduction of the energy barrier, which disappeared when alpha(SPFO)=0.5. This produces the flocculation of micelles giving rise to the formation of a non-birefringent coacervate, which is probably formed by unordered isometric clusters of micelles. PMID:17434522

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

    PubMed

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

    2014-01-01

    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

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

    PubMed

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

    2006-01-31

    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

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  10. Robust hollow devices and waveguides for Er:YAG laser radiation

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Matsuura, Y.; Miyagi, M.

    1998-04-01

    Fluorocarbon-polymer (FCP) coated silver hollow stainless steel (St) devices and waveguides have been developed for Er:YAG laser radiation. Full liquid phase techniques have been adopted to coat the silver and FCP layers inside the stainless steel hollow structure. Both straight and bent robust hollow devices have been fabricated as the output optical elements for the delivery system of medical Er:YAG lasers. A robust hollow waveguide with the length of about 1.6 m has also been realized as an actual delivery system.

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

    NASA Technical Reports Server (NTRS)

    Popovic, V.

    1973-01-01

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

  12. The 1980 stratospheric-tropospheric exchange experiment

    NASA Technical Reports Server (NTRS)

    Margozzi, A. P. (editor)

    1983-01-01

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

  13. Diagnostics for plasma processing (etching plasmas) (invited)

    SciTech Connect

    Hershkowitz, N.; Breun, R.A. [Engineering Research Center for Plasma Aided Manufacturing, University of Wisconsin--Madison, Madison, Wisconsin 53706 (United States)] [Engineering Research Center for Plasma Aided Manufacturing, University of Wisconsin--Madison, Madison, Wisconsin 53706 (United States)

    1997-01-01

    Plasma processing diagnostics play two different roles{emdash}characterization and control. The goal of plasma characterization is to establish connections of data with external parameters and to verify models. The goal of control diagnostics is to make noninvasive {ital in situ} measurements of relevant processing parameters. Diagnostics used in semiconductor etching are considered. These include Langmuir probes, laser induced fluorescence, optical emission spectroscopy, infrared and Fourier transform infrared absorption spectroscopy, mass spectrometry, microwave interferometry, and radio frequency diagnostics. An example is given of the use of many diagnostics in characterizing SiO{sub 2} and Si etching by fluorocarbons. {copyright} {ital 1997 American Institute of Physics.}

  14. Evaluation of C-14 removal techniques applicable to gaseous effluent from light-water-cooled reactors. Consultant report

    SciTech Connect

    Phillips, J.W.

    1980-02-01

    The production rate of carbon-14 in boiling water and pressurized water reactors is estimated and data are given on the chemical form of C-14 released by reactors and the pathways and amounts of release from reactors. Six methods for the capture of carbon dioxide are described and evaluated for their usefulness in capturing radioactive CO/sub 2/ from reactors: double alkaline scrubbing, direct alkaline scrubbing, fluorocarbon absorption, molecular sieve adsorption, ethanolamine scrubbing, and cryogenic distillation. The efficiencies of control systems based on these methods are estimated and the advantages and disadvantages of each are given. The available data on the cost of C-14 control is given.

  15. Perfluorocarbons and their use in Cooling Systems for Semiconductor Particle Detectors

    E-print Network

    Vacek, V; Ilie, S; Lindsay, S

    2000-01-01

    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.

  16. NASA/GSFC reliability evaluation of high temperature fiber optic cables

    NASA Technical Reports Server (NTRS)

    Sharma, A. K.; Jacobs, G.

    1992-01-01

    A high temperature (200 C rating) fiber-optic cable of fluorocarbon, silica-based glass, and polyimide coating, 100-micron core was evaluated for Goddard Space Flight Center applications. Testing was performed to evaluate attenuation characteristics of the cables during environmental stresses and exposure to Co-60 gamma radiation. The cables passed environmental tests, but after irradiation failed the established delta limit of 3 dB at 10 krads for a wavelength of 850 nm and 100 krads for a wavelength of 1300 nm.

  17. Biotransformation of 2,3,3,3-tetrafluoropropene (HFO1234yf)

    Microsoft Academic Search

    Paul Schuster; Ruediger Bertermann; Timothy A. Snow; Xing Han; George M. Rusch; Gary W. Jepson; Wolfgang Dekant

    2008-01-01

    2,3,3,3-Tetrafluoropropene (HFO-1234yf) is a non-ozone-depleting fluorocarbon replacement with a low global warming potential which has been developed as refrigerant. The biotransformation of HFO-1234yf was investigated after inhalation exposure. Male Sprague–Dawley rats were exposed to air containing 2000, 10,000, or 50,000 ppm HFO-1234yf for 6 h and male B6C3F1 mice were exposed to 50,000 ppm HFO-1234yf for 3.5 h in a dynamic exposure chamber (n=5\\/concentration).

  18. Determination of charge heterogeneity and level of unconjugated antibody by imaged cIEF.

    PubMed

    Lin, Joyce; Lazar, Alexandru C

    2013-01-01

    Imaged capillary isoelectric focusing (icIEF) is capable of monitoring the charge heterogeneity profile of conjugated antibodies. The electropherogram from icIEF can be integrated to quantitate the amount of unconjugated antibody present in a conjugate sample. This chapter describes an icIEF method where a conjugate sample was first prepared by mixing with appropriate ampholytes, pI markers, and additives. Then, the sample was focused in a fluorocarbon-coated fused silica capillary, where absorbance images were taken. Quantitation of the unconjugated antibody was achieved by using a calibration curve. PMID:23913156

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

    DOEpatents

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

    1991-01-01

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

  20. Characterization of a nanocoating using a MEMS tribogauge

    NASA Astrophysics Data System (ADS)

    Vijayasai, Ashwin; Ramachandran, Gautham; Sivakumar, Ganapathy; Anderson, Charlie; Gale, Richard; Dallas, Tim

    2012-03-01

    A chemisorbed fluorocarbon self-assembled monolayer (FSAM) layer on MEMS surfaces can greatly improve MEMS device reliability by reducing the in-use stiction force. In this work, a MEMS tribogauge that measures stiction force between two interacting surfaces has been used for FSAM coating and process parameter characterization. A commercially available nanocoating tool was used for depositing FSAM coatings. Five different coating recipes with different injection times for the FSAM precursor were evaluated with the tribogauge. The interacting surfaces of the tribogauge were exposed to many load cycles. These experiments allowed a preferred process to be determined.

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

    NASA Astrophysics Data System (ADS)

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

    2002-10-01

    In this work, the plasma etching characteristics of SiO2 thin films have been investigated using RF glow discharges fed with C3F6O and C3F6 mixted with oxygen. The results have been compared with performances obtained with CF4-CHF3 gases. The research was aimed at studying the utilization of new fluorocarbons in SiO2 plasma etching with a low impact on global warming. The following features have been investigated: SiO2 etch rate, SiO2/Si selectivity, contamination of silicon surfaces exposed to the plasma, and greenhouse gas emission.

  2. Perfluorocarbons and their use in cooling systems for semiconductor particle detectors

    Microsoft Academic Search

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

    2000-01-01

    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

  3. Characterization of elastomeric materials with application to design

    NASA Technical Reports Server (NTRS)

    Bower, Mark V.

    1986-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Bower, Mark V.

    1989-01-01

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

  5. Materials resistance to low earth orbit environmental effects

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

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

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

    NASA Technical Reports Server (NTRS)

    1977-01-01

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

  8. Unusual excess free energies of mixing in mixtures of partially fluorinated and hydrocarbon surfactants at the air-water interface: correlation with the structure of the layer.

    PubMed

    Jackson, Andrew J; Dong, Chu Chuan; Thomas, Robert K; Penfold, Jeffrey

    2015-01-13

    The air-water interface of three mixtures of partially fluorinated surfactants and hydrocarbon surfactants, C4F9C11H22N(CH3)3Br (fC4hC11TAB) with hexadecyltrimethylammonium bromide (C16TAB), (CF3)2C3F6C10H20N(CH3)3Br (fC5hC10TAB) with C16TAB, and C8F17C6H12N(CH3)3Br (fC8hC6TAB) with C18TAB, have been investigated using surface tension (ST) and neutron reflection (NR). Using the composition of the layer determined by NR, the pseudophase separation model was used to fit the variation of concentration for a specific ST to a free energy of mixing, G(E), that included adjustable quadratic, cubic and quartic terms. In all three cases, G(E) was found to be highly unsymmetrical, being approximately ideal at low surface fractions of hydrocarbon surfactant and repulsive at high fractions with a maximum value of 0.2-0.3RT. The corresponding structure of the layer was also determined by NR and showed that the initial ideal behavior of G(E) probably results from a balance of a gain in energy from a reduced immersion of the fluorocarbon chain, brought about by screening of the fluorocarbon from water by the hydrocarbon surfactant, and a loss from increased fluorocarbon-hydrocarbon repulsion. At higher concentration, there is no space in the layer for further screening and the fluorocarbon-hydrocarbon repulsion leads to the expected positive G(E). The calculated G(E) also indicated that there should be phase separation of the two components in the interface over a bulk composition range of about 60-95% hydrocarbon surfactant. However, experiment indicates no phase separation. It is suggested that there are a number of possible additional negative contributions to G(E) close to a phase transition, which are not possible for a true bulk phase separation, and which prevent surface phase separation unless it is strongly favored. PMID:25490580

  9. Correlating linactant efficiency and self-assembly: structural basis of line activity in molecular monolayers.

    PubMed

    Trabelsi, Siwar; Zhang, Zhongcheng; Zhang, Shishan; Lee, T Randall; Schwartz, Daniel K

    2009-07-21

    Surfactants exhibit characteristic phenomena, including the reduction of interfacial free energy, self-assembly into aggregates, and even the formation of lyotropic liquid crystalline phases at high concentrations. Our research has shown that a semifluorinated phosphonic acid can act as the two-dimensional analogue of a surfactant-a linactant-by reducing the line tension between hydrocarbon-rich and fluorocarbon-rich phases in a Langmuir monolayer. This linactant can also self-assemble into nanoscale clusters in a monolayer. Here, we explore the dependence of linactant behavior on molecular structure. Members of a homologous series of partially fluorinated phosphonic acids were synthesized and tested as linactants: CF(3)(CF(2))(n-1)(CH(2))(m)PO(3)H (abbreviated as FnHmPO(3)). The tests revealed that linactants with longer hydrophobic chains were most efficient in lowering line tension. For linactants with the same overall chain length, the length of the fluorocarbon block was correlated with efficiency. Thus, the linactant efficiency was ranked in the order F8H8PO(3) < F10H6PO(3) < F8H11PO(3) < F10H9PO(3). In all cases, linactant-containing Langmuir-Blodgett monolayers exhibited nanoscale molecular clusters with characteristic dimensions of 20-30 nm; enhanced linactant efficiency was systematically correlated with larger clusters. PMID:19594183

  10. Fabrication of robust hollow waveguide devices for Er:YAG laser light

    NASA Astrophysics Data System (ADS)

    Wang, You; Hiraga, Hajime; Matsuura, Yuji; Miyagi, Mitsunobu

    1997-04-01

    We report transmission properties of two kinds of robust bent hollow stainless steel (St) waveguides whose inner surface is coated by the thin silver (Ag) and fluorocarbon- polymer (FCP) layers. The bore size of the waveguides is 700 micrometer and all types of waveguides have been fabricated based on the liquid phase process, i.e., the process of silver mirror reaction for the silver layer and liquid flow- coating method for the fluorocarbon polymer layer. Measurements have been conducted for the fixed bent FCP- coated Ag hollow St waveguides with the length of 3 cm and the bending angles of 20 and 70 degrees, respectively for Er:YAG laser light. It turned out that the losses of 0.8 dB and 0.7 dB have been attained for the above 20 degree and 70 degree structures, respectively. As the St tube itself has the very robust structure and high heat conductivity compared with the corresponding glass hollow waveguide, the waveguide devices proposed in this paper will open a new application in medicine.

  11. Antisoiling technology: theories of surface soiling and performance of antisoiling surface coatings

    SciTech Connect

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

    1984-11-15

    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 surface of the second layer. The lowest possible surface energy state is dictated by the chemical and 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 rain-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.

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

    NASA Astrophysics Data System (ADS)

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

    1984-11-01

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

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

    SciTech Connect

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

    2008-05-15

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

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

    SciTech Connect

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

    1992-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

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

    PubMed

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

    2011-04-13

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

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

    NASA Technical Reports Server (NTRS)

    Shiner, C. S.

    1986-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Nwankwo, L.

    2013-12-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

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

    PubMed

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

    2012-09-26

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

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

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

    SciTech Connect

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

    1981-11-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  4. [Artificial blood in 1990: from a lifelong dream to today's reality].

    PubMed

    Vigneron, C

    1990-10-01

    Human blood is a very complex tissue. Therefore the idea of rediscovery its different cellular and plasmatic constituents would seem to be utopic. To be efficient the oxygen carrier, be it natural or by synthesis, must be stripped of antigenicity, be easily stockable and transportable. Thus these properties permit its use in urgent circumstances (accidents, natural disasters, war...), in those countries where there is a non existent or limited transfusional structure. This, under certain conditions, during very specific pathologies (localised ischemia for example). Among several hypotheses, they are two main lines of research that of "hemoglobin solutions" the oldest and the most physiological. This will be developed here in more lengthy terms due to our personal work on the subject. The second line of research concerns fluorocarbons, the most modern and artificial and without doubt better known to doctors and the public. 1. HEMOGLOBIN SOLUTIONS. Other than nephrotoxicity, which has proved affordable, research han revealed four large limitations with hemoglobin solutions (a high affinity for oxygen due to absence or loss of 2.3 DPG, a short half life due to vascular loss, rapid dimerisation and elimination of urine, insufficient concentration of prepared solutions (70 g/L) with as a result a weak oncotic pressure and oxygen supply, oxidation in methemoglobin). In order to overcome the two inconveniences, proposals were made to modify hemoglobin chemically, the idea coming from the putting into operation of potential analogues to or substitutes for 2.3 DPG which it is advisable to bring or to keep--by covalent bonding--near to the fixation site of the natural ligand. Thus our group has already deposed several patents and is now working on a complex hemoglobin-dextran benzine tetracarboxylate which appears promising. Today, due to the quality and reproduction of the results obtained on animals with chemically modified hemoglobin preparations clinical assays should be carried out soon. 2. FLUOROCARBONS. In this very different approach which uses totally synthetic compounds oxygen carrying can only be realised in dissolved form. Due to this fluorocarbons, even though they are remarkable solvents of gas, do not reach their full efficiency unless the patient breathes in a very rich oxygen atmosphere. This is therefore a considerable limiting factor. The other big problem is the insolubility of these compounds and therefore the need to emulsify them, but unfortunately these emulsions are difficult, if not impossible to stabilise.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2081328

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

    PubMed Central

    2009-01-01

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

  6. Economical Analysis about Ammonia Absorption Refrigeration Plants

    NASA Astrophysics Data System (ADS)

    Takei, Toshitaka

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

  7. Electrokinetics of Polar Liquids in Contact with Non-Polar Surfaces

    E-print Network

    Lin, Chih-Hsiu; Chaudhury, Manoj K

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2000-10-01

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

  9. Effect of surface temperature on plasma-surface interactions in an inductively coupled modified gaseous electronics conference reactor

    SciTech Connect

    Zhou Baosuo; Joseph, Eric A.; Sant, Sanket P.; Liu Yonghua; Radhakrishnan, Arun; Overzet, Lawrence J.; Goeckner, Matthew J. [Department of Electrical Engineering, University of Texas at Dallas, Richardson, Texas 75083-0688 (United States)

    2005-11-15

    The effect of wall temperature, from 50 to 200 deg. C, on gas phase chemistry and substrate etching rates has been studied in inductively coupled CF{sub 4} plasma under two distinctive initial wall conditions, namely 'clean' and 'seasoned'. During plasma etching, we found that the gas phase chemistry exhibits a weak dependence on the initial wall cleanliness when the wall is either cold (50 deg. C) or hot (200 deg. C). In the mid-temperature range, the wall cleanliness can strongly affect gas phase chemistry. The study of temperature dependence of the fluorocarbon film deposition on the substrate indicates that ion-assisted incorporation, direct ion incorporation and ion-assisted desorption are the major factors determining film growth and removal. Ion-assisted incorporation and desorption are surface-temperature-dependent, while direct ion incorporation is independent of the surface temperature.

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    Partition in phase separated aqueous polymer solutions is a cell separation procedure thought to be adversely influenced by gravity. In preparation for performing cell partitioning experiments in space, and to provide general information concerning the demixing of immiscible liquids in low gravity, a series of phase separated aqueous polymer solutions have been flown on two shuttle flights. Fluorocarbon oil and water emulsions were also flown on the second flight. The aqueous polymer emulsions, which in one g demix largely by sedimentation and convection due to the density differences between the phases, demixed more slowly than on the ground and the final disposition of the phases was determined by the wetting of the container wall by the phases. The demixing behavior and kinetics were influenced by the phase volume ratio, physical properties of the systems and chamber wall interaction. The average domain size increased linearly with time as the systems demixed.

  11. Breakdown and discharge regimes in standard and micrometer size dc discharges

    NASA Astrophysics Data System (ADS)

    Škoro, N.

    2012-11-01

    In this paper, an overview of our recent experimental studies of the breakdown and operation of non-equilibrium discharges in centimetre and micrometer size geometries is presented. In the centimetre size geometries, we focused on elementary processes and phenomenology in gases used for some of the currently most attractive applications of low temperature plasmas - fluorocarbon gases (CF4, CHClF2) and water vapour. Measurements were performed at electrode separation d = 1.1 cm, in a pressure range from 0.1 to 5 Torr. In the case of micro-discharges, the emphasis was on testing the validity of standard scaling laws and proper determination of scaling parameters pd and j/p2. This was done at electrode gaps of 200 and 500 ?m and pressures of 50 and 20 Torr in argon. The investigation is based on measurements of breakdown potentials (Paschen curves) and Volt-Ampere characteristics, supported by simultaneous ICCD imaging of the discharges.

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

    NASA Technical Reports Server (NTRS)

    Kendall, B. R. F.

    1983-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Wu, Te-Kao (Inventor)

    1996-01-01

    The design and performance of a wide angle, single screen, frequency selective surface (FSS) with gridded square-loop path elements are described for diplexing closely separated signal bands, for example, X- and Ku-band signals in an Orbiting Very Long Baseline Interferometer (OVLBI) earth station reflector antenna system, as well as other applications such as military and commercial communications via satellites. Excellent agreement is obtained between the predicted and measured results of this FSS design using the gridded square-loop patch elements sandwiched between 0.0889 cm thick tetrafluoroethylene fluorocarbon polymer (PTFE) slabs. Resonant frequency drift is reduced by 1 GHz with an incidence angle from 0 deg normal to 40 deg from normal.

  14. Burst behavior at a capillary tip: Effect of low and high surface tension.

    PubMed

    Agonafer, Damena D; Lopez, Ken; Palko, James W; Won, Yoonjin; Santiago, Juan G; Goodson, Kenneth E

    2015-10-01

    Liquid retention in micron and millimeter scale devices is important for maintaining stable interfaces in various processes including bimolecular separation, phase change heat transfer, and water desalination. There have been several studies of re-entrant geometries, and very few studies on retaining low surface tension liquids such as fluorocarbon-based dielectric liquids. Here, we study retention of a liquid with very low contact angles using borosilicate glass capillary tips. We analyzed capillary tips with outer diameters ranging from 250 to 840?m and measured Laplace pressures up to 2.9kPa. Experimental results agree well with a numerical model that predicts burst pressure (the maximum Laplace pressure for liquid retention), which is a function of the outer diameter (D) and capillary exit edge radius of curvature (r). PMID:26046980

  15. Stable superhydrophobic and lipophobic conjugated polymers films.

    PubMed

    Nicolas, Mael; Guittard, Frédéric; Géribaldi, Serge

    2006-03-28

    With a view to developing repellent materials combining both low surface energy and rough structure, original semi-fluorinated polythiophenes have been chemically and electrochemically synthesized and characterized by cyclic voltammetry, GPC, and UV-visible measurements. Polymer films have been deposited onto different substrates by drop casting a soluble polymer fraction on glass plate or by electrodeposition on ITO plate. Surface properties and particularly water and oil repellencies have been investigated by goniometry and correlated with the surface morphology and structure observed by SEM. The incorporation of fluorocarbon chains in the rigid polythiophene backbone yields very low surface free energy materials. Moreover, the way of deposition has a huge influence on the quality and performance of the film surface properties. Electroformed polymers, due to rough surfaces, exhibit great super-hydrophobic and lipophobic properties together with exceptional time stability. PMID:16548561

  16. Aviation gas turbine lubricants - military and civil aspects: aviation fuel and lubricants - performance testing; Proceedings of the Aerospace Technology Conference and Exposition, Long Beach, CA, October 14-17, 1985

    SciTech Connect

    Not Available

    1985-01-01

    Research and development programs in the areas of gas turbine lubricants for civil and military aviation and the performance testing of aviation gas turbine fuels and lubricants are discussed. The topics addressed include: laboratory and field evaluation of a high temperature jet engine oil, performance advantages of high load aviation lubricants, fluorocarbon elastomer compatibility with gas turbine lubricants, potential benefits in the development of a dedicated helicopter transmission lubricant, and feasibility of formulating advanced four centistoke gas turbine oils. Also covered are: advanced lubricants for aircraft turbine engines, future trends for U.S. Naval aviation propulsion system lubricants, electrochemical evaluation of corrosivity in turbine engine oils, the influence of esters on elastomer seals, deposition in gas turbine oil systems, development of the portable water separometer for the WSIM test, influence of JFTOT operating parameters on the assessment of fuel thermal stability, and evaluation of JFTOT tube deposits by carbon burnoff.

  17. Electrical conduction control of carbon nanowalls

    SciTech Connect

    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

    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.

  18. Versatile Coating

    NASA Technical Reports Server (NTRS)

    1990-01-01

    A radome at Logan Airport and a large parabolic antenna at the Wang Building in Massachusetts are protected from weather, corrosion and ultraviolet radiation by a coating, specially designed for antennas and radomes, known as CRC Weathertite 6000. The CRC 6000 line that emerged from Boyd Coatings Research Co., Inc. is a solid dispersion of fluorocarbon polymer and polyurethane that yields a tough, durable film with superior ultraviolet resistance and the ability to repel water and ice over a long term. Additionally, it provides resistance to corrosion, abrasion, chemical attacks and impacts. Material can be used on a variety of substrates, such as fiberglass, wood, plastic and concrete in addition to steel and aluminum. In addition Boyd Coatings sees CRC 6000 applicability as an anti-icing system coated on the leading edge of aircraft wings.

  19. Cathodic electrocatalyst layer for electrochemical generation of hydrogen peroxide

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  20. Laboratory Studies of Chemical and Photochemical Processes Relevant to Stratospheric Ozone

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    This paper reports on the first experimental study of the energies of noncovalent fluorine bonding in a protein-ligand complex in the absence of solvent. Arrhenius parameters were measured for the dissociation of gaseous deprotonated ions of complexes of bovine ?-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.

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

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

  4. Pulsed Plasma Thruster Plume Study: Symmetry and Impact on Spacecraft Surfaces

    NASA Technical Reports Server (NTRS)

    Arrington, Lynn A.; Marrese, Colleen M.; Blandino, John J.

    2000-01-01

    Twenty-four witness plates were positioned on perpendicular arrays near a breadboard Pulsed Plasma Thruster (PPT) to collect plume constituents for analysis. Over one million shots were fired during the experiment at 43 J using fluorocarbon polymer propellant. The asymmetry of the film deposition on the witness plates was investigated with mass and thickness measurements and correlated with off-axis thrust vector measurements. The composition of the films was determined. The transmittance and reflectance of the films were measured and the absorption coefficients were calculated in the wavelength range from 350 to 1200 mn. These data were applied to calculate the loss in signal intensity through the films, which will impact the visibility of spaceborne interferometer systems positioned by these thrusters.

  5. Nondestructive decontamination of radioactive electronic equipment by fluorinated surfactant solutions

    SciTech Connect

    Yam, C.S.; Harling, O.K. [Massachusetts Inst. of Technology, Cambridge, MA (United States). Dept. of Nuclear Engineering; Kaiser, R. [Entropic Systems, Inc., Winchester, MA (United States)

    1995-12-31

    The application of ESI`s enhanced particle removal process, initially developed for the cleaning of inertial guidance instrument parts, to the nondestructive decontamination of nuclear equipment is discussed. 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 non-toxic, nonflammable, generally safe to use, and do not present a hazard to the atmospheric ozone layer. An experimental cleaning system has been developed by ESI to demonstrate the application of this cleaning process to nuclear decontamination of electronic circuit boards. A high degree of decontamination is obtained and with no resulting physical damage to the circuits.

  6. Ultrasonic decontamination in perfluorinated liquids of radioactive circuit boards

    SciTech Connect

    Yam, C.S.; Harling, O.K. [Massachusetts Institute of Technology, Cambridge, MA (United States); Kaiser, R.

    1994-12-31

    A laboratory-scale ultrasonic decontamination system has been developed to demonstrate the application of Entropic System`s enhanced particle removal process to the radioactive decontamination of electronic circuit boards. The process uses inert perfluorinated liquids as the working media; the liquids have zero ozone depletion potential, are nontoxic, non-flammable, and are generally recognized as nonhazardous materials. The parts to be cleaned are first sonicated with a dilute solution of a high-molecular-weight fluorocarbon surfactant in an inert perfluorinated liquid. The combination of ultrasonic agitation and liquid flow promotes the detachment of the particles from the surface of the part being cleaned, their transfer from the boundary layer into the bulk liquid, and their removal from the cleaning environment, thereby reducing the probability of particle redeposition. After the cleaning process, the parts are rinsed with the pure perfluorinated liquid to remove residual surfactant. The parts are recovered after the perfluorinated liquid is evaporated into air.

  7. Alternative training agents, Phase 1. Survey of near-term-candidate fire-extinguishing agents and predicting properties of halocarbon mixtures. Volume 1. Final report

    SciTech Connect

    Nimitz, J.S.; Tapscott, R.E.; Skaggs, S.R.; Beeson, H.D.

    1991-02-01

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

  8. Coolant controversy heats up

    SciTech Connect

    Shanley, A.

    1997-11-01

    In 1987, nations of the world banded together under the Montreal Protocol to help protect the earth`s ozone layer. Now, ten years and $2.4 billion in new fluorocarbon R and D later, the ozone hole is still with us, as a black market in illegal chlorofluorocarbons thrives and legal trade in recycled CFCs continues. Unfortunately, each alternative to CFCs poses tradeoffs. Some hydrochlorofluorocarbons present lubricant compatibility problems, and, because they are also somewhat ozone depleting, they`ll be phased out in the US between 2010 and 2030, and earlier in Europe. Chlorine-free hydrofluorocarbons contribute to global warming and some require lubricant changes and retooling, while the processes that make them emit halogenated organics. This paper discusses compatibility, flammability, global warming, and supply problems.

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

    NASA Astrophysics Data System (ADS)

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

    1999-02-01

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

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

    NASA Astrophysics Data System (ADS)

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

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

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

    PubMed Central

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

    2008-01-01

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

  12. Plasma treatment of polymers for surface and adhesion improvement

    NASA Astrophysics Data System (ADS)

    Hegemann, Dirk; Brunner, Herwig; Oehr, Christian

    2003-08-01

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

  13. Acute inhalation toxicity evaluation of a 93:7 mixture of perfluoro-2-butene and 1-bromopropane, a replacement candidate for ozone depleting substances. Interim report, July--August 1997

    SciTech Connect

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

    1997-10-01

    The DoD requires the development of toxicity profiles for chemical substitute candidates proposed to replace ozone depleting substances such as chloro- and fluorocarbons and halons. A 93:7 mixture of perfluoro-2-butene and 1-bromopropane was identified as a possible replacement candidate for ozone-depleting fire extinguishants. An acute inhalation toxicity test utilizing male and female Fischer 344 rats was performed on this test material. No deaths occurred in any of the rats exposed to 5.3 mg/L of the 93:7 perfluoro-2-butene and 1-bromopropane mixture. Body weights of male and female rats during the subsequent 14-day observation period were unaffected by treatment. The test material did not produce acute toxicity via the inhalation route.

  14. The 1977 intertropical convergence zone experiment

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

    Data are presented from the 1977 Intertropical Convergence Zone (ITCZ) Experiment conducted in the Panama Canal Zone in July 1977. Measurements were made daily over a 16-day period when the ITCZ moved across the Canal Zone. Two aircraft (Learjet and U-2) flew daily and provided data from horizontal traverses at several altitudes to 21.3 km of ozone, temperature, pressure, water vapor, aerosols, fluorocarbons, methane, nitrous oxide, nitric oxide, and nitric acid. Balloonsondes flown four times per day provided data on ozone, wind fields, pressure, temperature, and humidities to altitudes near 30 km. Rocketsondes provided daily data to altitudes near 69 km. Satellite photography provided detailed cloud information. Descriptions of individual experiments and detailed compilations of all results are provided.

  15. A proximity focusing RICH detector for kaon physics at Jefferson lab hall A

    SciTech Connect

    F. Garibaldi; E. Cisbani; S. Colilli; F. Cusanno; S. Frullani; R. Fratoni; F. Giuliani; M. Gricia; M. Iodice; M. Lucentini; L. Pierangeli; F. Santavenere; G.M. Urciuoli; P. Veneroni; G. De Cataldo; R. De Leo; L. Lagamba; E. Nappi; V. Paticchio; J. LeRose; B. Kross; B. Reitz; J. Segal; C. Zorn; H. Breuer

    2003-04-01

    Important information on the LN interaction can be obtained from High Resolution Hypernuclear Spectroscopy experiments with electromagnetic probes. A challenging experiment on electroproduction of hypernuclei is scheduled for 2003 in Hall A at Jefferson Lab. One of the challenges is the high performance particle identification system needed. The signal is expected to be rare compared to the very high pion and proton backgrounds due to the small electron and kaon detection angles. The ''standard'' Hall A PID apparatus (TOF and two aerogel threshold Cherenkov detectors) does not provide sufficient suppression of the background. Simulations and calculations have shown that a RICH detector would solve the problem. A proximity focusing fluorocarbon/CsI detector similar to the ALICE RICH detector has been designed, built, tested and commissioned. The results show that the detector performs as expected.

  16. Development and evaluation of elastomeric materials for geothermal applications

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

  17. A micro-machined safety valve for power applications with improved sealing

    NASA Astrophysics Data System (ADS)

    Debray, A.; Nakakubo, T.; Yokoi, A.; Mogi, S.; Ueda, K.; Shibata, M.; Takeuchi, S.; Fujita, H.

    2006-09-01

    A novel micro-safety valve for portable hydrogen fuel cells has been designed, fabricated and characterized. This device is intended to prevent over-pressure on the hydrogen side of the fuel cell. A careful study of its sealing properties has been conducted under conditions at which it is nearly open. The leakage rate depending on the size of the sealing surface and on the material of the gasket (fluorocarbon and parylene films) has been investigated using hydrogen gas. The experimental results show that small sealing surfaces lead to small leakage rates and that the parylene films are easily damaged, leading to important leakage rates. Moreover, it is shown that the resistance to flow of the device is diminished by reducing the width of the valve nozzle.

  18. The importance of the Montreal Protocol in protecting climate

    PubMed Central

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

    2007-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Bartoszek, E. J.; Nannelli, P.

    1975-01-01

    Coating formulations were developed consisting of latex blends of fluorocarbon polymers, acrylic resins, stabilizers, modifiers, other additives, and a variety of inorganic pigments. Suitable latex primers were also developed from an acrylic latex base. The formulations dried to touch in about one hour and were fully dry in about twenty-four hours under normal room temperature and humidity conditions. The resulting coatings displayed good optical and mechanical properties, including excellent bonding to (pre-treated) substrates. In addition, the preferred compositions were found to be self-extinguishing when applied to nonflammable substrates and could meet the offgassing requirements specified by NASA for the intended application. Improvements are needed in abrasion resistance and hardness.

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

    NASA Astrophysics Data System (ADS)

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

    2005-06-01

    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.

  1. Glazings 101

    SciTech Connect

    Kensil, D.

    1980-09-01

    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)

  2. Manufacture and quality control of interconnecting wire hardnesses, Volume 1

    NASA Technical Reports Server (NTRS)

    1972-01-01

    A standard is presented for manufacture, installation, and quality control of eight types of interconnecting wire harnesses. The processes, process controls, and inspection and test requirements reflected are based on acknowledgment of harness design requirements, acknowledgment of harness installation requirements, identification of the various parts, materials, etc., utilized in harness manufacture, and formulation of a typical manufacturing flow diagram for identification of each manufacturing and quality control process, operation, inspection, and test. The document covers interconnecting wire harnesses defined in the design standard, including type 1, enclosed in fluorocarbon elastomer convolute, tubing; type 2, enclosed in TFE convolute tubing lines with fiberglass braid; type 3, enclosed in TFE convolute tubing; and type 5, combination of types 3 and 4. Knowledge gained through experience on the Saturn 5 program coupled with recent advances in techniques, materials, and processes was incorporated.

  3. Metallic and nonmetallic coatings for ICF targets

    SciTech Connect

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

    1981-04-17

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

  4. Nano-coatings on carbon structures for interfacial modification

    NASA Astrophysics Data System (ADS)

    Pulikollu, Rajasekhar V.

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

  5. Gas chromatographic analysis of toxic edemagenic inhalation compounds

    SciTech Connect

    Shih, M.L.; Smith, J.R.; McMonagle, J.D. (Army Medical Research Inst. of Chemical Defense, Aberdeen Proving Ground, MD (United States))

    1990-01-01

    Different megabore column and packed column phases were evaluated for their suitability in the gas chromatographic analysis of three toxic polyhalogenated compounds (phosgene, TFD, and PFIB). Adsorbent type stationary phases provide better retention and separation for the volatile fluorocarbons than do polar and nonpolar liquid phases. The reactivity of phosgene precludes the use of many phases having hydroxy, amino, or cyano functional groups. Silica gel is still the column of choice for phosgene. The use of gas sampling bags and gas-tight syringes can provide reliable quantitation of these compounds in air samples. TFD and PFIB exhibit different electron capture mechanisms and detector temperature dependency. The mechanisms are supported by the results of negative ion mass spectrometry.

  6. National Institute for Occupational Safety and Health Cooperative Agreement, Award No. 1, U01 oh 01249-01. Final report

    SciTech Connect

    Rom, W.N.

    1982-12-31

    A walk-through survey and a followup on/site environmental and medical evaluation of potentially exposed workers were carried out at Hill Air Force Base, Ogden, Utah. Followup on/site environmental and medical evaluations of potentially exposed workers were conducted at Koldaire, Inc., Salt Lake City, Utah. Past medical records at Hill Air Force Base and historical worker-exposure information were deemed adequate to reconstruct probable exposures to hazardous materials during the performance of various work assignments at the base and to permit a morbidity study to be conducted. Possible exposures in this area of work include fluorocarbons, phosgene, hydrogenchloride, hydrogen-fluoride, welding fumes and cadmium. It was recommended that respirators be worn by refrigeration repairmen, that medical surveillance be performed yearly, and that eye protection be worn during welding and soldering operations.

  7. Spacecraft dielectric material properties and spacecraft charging

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

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

  8. Controlling modulus and morphology of hydrogel tubes through surface modification.

    PubMed

    Enescu, Cristina; Shoichet, Molly S

    2004-01-01

    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

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

    SciTech Connect

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

    2010-01-01

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

  10. Lyotropic liquid crystal phases of phytantriol in a protic ionic liquid with fluorous anion.

    PubMed

    Shen, Yan; Greaves, Tamar L; Kennedy, Danielle F; Weerawardena, Asoka; Kirby, Nigel; Song, Gonghua; Drummond, Calum J

    2014-10-21

    The phase behaviour of phytantriol in the protic ionic liquid (PIL) 1-methylimidazolium pentadecafluorooctanoate (MImOF) and four different MImOF-water compositions was investigated by small- and wide-angle X-ray scattering (SAXS/WAXS), cross polarised optical microscopy (CPOM) and infrared spectroscopy (IR). MImOF is a distinct protic ionic liquid in that it contains a fluorocarbon anion and a hydrocarbon cation. This leads to MImOF having an unusual liquid nanostructure, such that it contains fluorocarbon, hydrocarbon and polar domains. No lyotropic liquid crystal phases were observed for phytantriol in neat MImOF. However, on addition of water, lamellar, cubic Ia3¯d and micellar phases were observed for specific MImOF-phytantriol-water compositions at room temperature, and up to 60 °C. The phase behaviour for phytantriol in the solvent mixture of 25 wt%-MImOF-75 wt%-water was the most similar to the phytantriol-water phase diagram. Only this MImOF-water composition supported the Ia3¯d cubic phase, which had a lattice parameter between 100-140 Å compared to 86-100 Å in deionised water, indicating significant swelling due to the MImOF. IR spectroscopy showed that a percentage of the water molecules were hydrogen bonded to the N-H of the MIm cation, and this water decreased the hydrogen bonding present between the cation and anion of the ionic liquid. This investigation furthers our understanding of the interaction of ionic liquids with solutes, and the important role that the different IL nanostructures can have on influencing these interactions. PMID:25177837

  11. Diode Laser Absorption Measurements of Species Concentrations

    NASA Astrophysics Data System (ADS)

    Anderson, Harold

    1996-10-01

    Characterization of gas phase species densities is critically important to the understanding of complex plasma chemistry and the mechanistic development of plasma processes. Infrared diode laser absorption provides a relatively simple and cost effective means of gaining access to species concentrations for a large number radicals important to plasma etching. It is particularly well suited for aiding it process development in new high density plasma etch tools where the combination of low pressure and high dissociation means the plasma chemistry component is largely comprised of atomic or two- and three-body molecular fragment species at low partial pressures. This paper describes how single-pass, FM diode laser absorption spectroscopy has been used to measure chlorine and fluorocarbon dissociation in inductively coupled discharges in a variety of both laboratory and commercial plasma etchers. The detection of atomic chlorine by measurement of the spin orbit transition around 882 cm-1 in a GEC/ICP Reference Cell plasma is discussed. Both bulk and spatially resolved diode laser measurements were performed. The results are used to show chlorine is largely dissociated throughout the chamber at almost power in the inductive mode and that a large fraction of the atomic chlorine is in the long lived ^2P_1/2 spin orbit level due to increased electron collisions at high power. Measurements of CFx radicals made in both the Reference Cell and in commercial ICP plasma etchers are also discussed. A relatively small, portable version of the diode laser system is described which has actually been transported and used on site at semiconductor fab facilities for etch tool process characterization. The utility of this information in defining critical reaction pathways in complex fluorocarbon oxide etch chemistries is described. (This work has been supported by grants from both SEMATECH and Sandia National Labortories)

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

    SciTech Connect

    Shoeb, Juline; Wang Mingmei; Kushner, Mark J. [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

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

  13. Chemical dry cleaning and pretreatment on the electrical and reliability characteristic of high-k gate dielectrics in MOS device

    NASA Astrophysics Data System (ADS)

    Cheng, Chin-Lung; Wang, Tien-Ko; Chang-Liao, Kuei-Shu

    2003-07-01

    Effect of chemical dry cleaning (CDC) and pre-treatment (NH3 annealing) on the interface property of high-K gate dielectrics (NiTiO3) in MOS device have been investigated. A surface layer is damaged due to oxide dry etching (CHF3/CF4/Ar) process in active region formation. This damaged layer was generally removed by wet etching (HF) however it creates a rough layer on the substrate surface. It appears that the surface roughness by plasma dry etching is better then that by HF wet oxide etching. When the metal is directly deposited on the silicon substrate, a poor interface quality leads to a high leakage current. A damage-free, smooth surface, and thin interfacial layer formed on substrate surface are important for high-k gate dielectric process. Therefore, a method using Chemical Dry Cleaning (CF4/O2) is adopted after dry oxide etching (CHF3/CF4/Ar). In addition, CDC can then be adopted to effectively remove fluorocarbon residue and Si-F and Si-C bonds on the silicon surface etched in fluorocarbon plasma chemistry. After CDC, pre-deposition treatment can be employed to inhibit the growth of the interfacial layer. The pre-treatment strategies (NH3 annealing) are used to prevent silicide formation and to elevate the interface property of the devices. Finally, post deposition annealing (N2 annealing) can be performed to reduce the leakage current. These approaches not only strengthen the structure of Si-N bonds, but also improve the smoothness and uniformity at the interface of the metal oxide/silicon substrate.

  14. Refrigeration and Air-Conditioning Technology Workshop

    NASA Astrophysics Data System (ADS)

    Lewis, P. J.; Counce, D. M.

    1993-12-01

    The Alternative Fluorocarbon Environmental Acceptability Study (AFEAS), a consortium of fluorocarbon manufacturers, and the U.S. Department of Energy (DOE) are collaborating on a project to evaluate the energy use and global warming impacts of CFC alternatives. The goal of this project is to identify technologies that could replace the use of CFC's in refrigeration, heating, and air-conditioning equipment; to evaluate the direct impacts of chemical emissions on global warming; and to compile accurate estimates of energy use and indirect CO2 emissions of substitute technologies. The first phase of this work focused on alternatives that could be commercialized before the year 2000. The second phase of the project is examining not-in-kind and next-generation technologies that could be developed to replace CFC's, HCFC's, and HFC's over a longer period. As part of this effort, Oak Ridge National Laboratory held a workshop on June 23-25, 1993. The preliminary agenda covered a broad range of alternative technologies and at least one speaker was invited to make a brief presentation at the workshop on each technology. Some of the invited speakers were unable to participate, and in a few cases other experts could not be identified. As a result, those technologies were not represented at the workshop. Each speaker was asked to prepare a five to seven page paper addressing six key issues concerning the technology he/she is developing. These points are listed in the sidebar. Each expert also spoke for 20 to 25 minutes at the workshop and answered questions from the other participants concerning the presentation and area of expertise. The primary goal of the presentations and discussions was to identify the developmental state of the technology and to obtain comparable data on system efficiencies.

  15. Ion densities of CH2F+ and CHF2+ generated by dissociative ionization of charge exchange collisions in Ar or Kr diluted CH2F2 Plasmas

    NASA Astrophysics Data System (ADS)

    Sekine, Makoto; Kondo, Yusuke; Miyawaki, Yudai; Ishikawa, Kenji; Hayashi, Toshio; Takeda, Keigo; Kondo, Hiroki; Hori, Masaru; Plasma Nanotechnology Team

    2014-10-01

    Hydro-fluorocarbon gas, CHxF4-x is used for SiO2 and Si3N4 etching, where the reduction of F in molecule leads high selectively. High selectively were reported as using hydro-fluorocarbon gases having more molecular mass such as C5HF7. H reacts to N and removes it from Si3N4. Therefore H works as an etchant of Si3N4. By using CH2F2 gas as an addition of conventional process, high selectively was obtained. In order to understand the etch mechanism for the CH2F2 containing plasma, we investigate the gas phase species and reaction to produce etchants. In many cases, multiple fragmentation of the parent gas is suppressed by dilution of large amount of rare gas (M). Besides, dissociative ionization of charge exchange collisions, CH2F2 + M+ --> CH2 F+ + F . + M* and CHF2+ + H . + M* (M = Ar, Kr) has not been clarified yet. Here we show that the CH2F+ ion was dominant in the Ar-diluted plasma, because the channel of resonant dissociative ionization between Ar+ (ca. 15.8 eV) and C-F bonding cleavage (ca. 15.6 eV) became dominant. In contrast, for the Kr-diluted plasma, similar exchange between Kr+ (ca. 14.0 eV) and C-H bonding cleavage (ca. 13.9 eV) generated dominantly CHF2+ ion. This behavior in the fraction of ion densities in the CH2F2 plasma affects significantly to the selectivity.

  16. Effect of SiO2 on relaxation phenomena and mechanism of ion conductivity of [Nafion/(SiO2)x] composite membranes.

    PubMed

    Di Noto, Vito; Gliubizzi, Rocco; Negro, Enrico; Pace, Giuseppe

    2006-12-14

    This report describes a study of the effect of SiO2 nanopowders on the mechanism of ionic motion and interactions taking place in hybrid inorganic-organic membranes based on Nafion. Five nanocomposite membranes of the formula [Nafion/(SiO2)x] with SiO2 ranging from 0 to 15 wt % were prepared by a solvent casting procedure. TG measurements demonstrated that the membranes are thermally stable up to 170 degrees C but with the loss water it changes the cluster environments and changes the conductivity properties. MDSC investigations in the 90-300 degrees C temperature range revealed the presence of three intense overlapping endothermal peaks indicated as I, II, and III. Peak I measures the order-disorder molecular rearrangement in hydrophilic polar clusters, II corresponds to the endothermic decomposition of -SO3 groups, and III describes the melting process in microcrystalline regions of hydrophobic fluorocarbon domains of the Nafion moiety. ESEM with EDAX measurements revealed that the membranes are homogeneous materials with smooth surfaces. DMA studies allowed us to measure two relaxation modes. The mechanical relaxation detected at ca. 100 degrees C is attributed to the motion of cluster aggregates of side chains and is diagnostic for R-SO3H...SiO2 nanocluster interactions. DMA disclosed that at SiO2/-SO3H (psi) molar ratios lower than 1.9, the oxoclusters act to restrict chain mobility of hydrophobic domains of Nafion and the dynamics inside polar cages of [Nafion/(SiO2)x] systems; at psi higher than 1.9, the oxoclusters reduce the cohesiveness of hydrophilic polar domains owing to a reduction in the density of cross-links. FT-IR and FT-Raman studies of the [Nafion/(SiO2)x] membranes indicated that the fluorocarbon chains of Nafion hydrophobic domains assume the typical helical conformation structure with a D(14pi/15) symmetry. These analyses revealed four different species of water domains embedded inside polar cages and their interconnecting channels: (a) bulk water [(H2O)n]; (b) water solvating the oxonium ions directly interacting with sulfonic acid groups [H3O+...SO3(-)-].(H2O)n; (c) water aggregates associated with H3O+ ions [H3O+.(H2O)n]; and (d) low associated water species in dimer form [(H2O)2]. The conductivity mechanism and relaxation events were investigated by broadband dielectric spectroscopy (BDS). [Nafion/(SiO2)x] nanocomposite membranes were found to possess two different molecular relaxation phenomena which are associated with the alpha-relaxation mode of PTFE-like fluorocarbon domains and the beta-relaxation mode of acid side groups of the Nafion component. Owing to their strong coupling, both these relaxation modes are diagnostic for the interactions between the polar groups of the Nafion host polymer and the (SiO2)x oxoclusters and play a determining role in the conductivity mechanism of the membranes. The studies support the proposal that long-range proton charge transfer in [Nafion/(SiO2)x] composites takes place due to a mechanism involving exchange of the proton between the four water domains. This latter proton transfer occurs owing to a subsequent combination of domain intersections resulting from the water domain fluctuations induced by the molecular relaxation events of host Nafion polymer. PMID:17149919

  17. Low Temperature Plasma Surface Interactions: Atomic Layer Etching And Atmospheric Pressure Plasma Jet Modification Of Biomaterials

    NASA Astrophysics Data System (ADS)

    Oehrlein, Gottlieb

    2013-09-01

    Control of plasma-surface interactions is essential for successful application of low temperature plasma to materials processing. We review work performed in our laboratory in two areas: First, low pressure plasma surface interaction mechanisms aimed at achieving atomic precision in etching materials in the semiconductor industry. We discuss sequential reactions of surface passivation followed by directional low energy ion attack for ``volatile product'' removal to establish for what conditions self-limiting behavior required for Atomic Layer Etching (ALE) can be established using prototypical SiO2 -Si/fluorocarbon-Ar materials/etching systems. Second, studies of plasma-surface interactions related to application of a non-equilibrium atmospheric pressure plasma jet (APPJ) for modification of biomaterials are discussed. Changes in surface chemistry/biological activity of lipopolysaccharide (LPS) exposed to the APPJ plume/effluent in a controlled environment are reviewed. The results clarify how jet chemistry and interactions of plasma with the environment impact the consequences of APPJ-biomaterial-surface interactions. Control of plasma-surface interactions is essential for successful application of low temperature plasma to materials processing. We review work performed in our laboratory in two areas: First, low pressure plasma surface interaction mechanisms aimed at achieving atomic precision in etching materials in the semiconductor industry. We discuss sequential reactions of surface passivation followed by directional low energy ion attack for ``volatile product'' removal to establish for what conditions self-limiting behavior required for Atomic Layer Etching (ALE) can be established using prototypical SiO2 -Si/fluorocarbon-Ar materials/etching systems. Second, studies of plasma-surface interactions related to application of a non-equilibrium atmospheric pressure plasma jet (APPJ) for modification of biomaterials are discussed. Changes in surface chemistry/biological activity of lipopolysaccharide (LPS) exposed to the APPJ plume/effluent in a controlled environment are reviewed. The results clarify how jet chemistry and interactions of plasma with the environment impact the consequences of APPJ-biomaterial-surface interactions. Based on collaborations with D. Metzler, S. Engelmann, R. Bruce, E. Joseph, E. Bartis, C. Hart, Q.-Y. Yang, J. Seog, T.-Y. Chung, H.-W. Chang, and D.B. Graves. We gratefully acknowledge funding from US Department of Energy (DE-SC0005105; DE-SC0001939) and National Science Foundation (CBET-1134273; PHY-1004256).

  18. The characterization of plasma-surface interactions using the inductively coupled gaseous electronics conference reference cell platform

    NASA Astrophysics Data System (ADS)

    Joseph, Eric Andrew

    The ability to systematically vary the amount of plasma-surface interaction for any given plasma process can provide a novel approach to controlling the gas-phase plasma chemistry, the physical parameters of the plasma and the reaction pathways which govern etch and deposition at the sample surface. In this dissertation, such systematic methods to control plasma-surface interactions are explored during the processing of silicon, silicon dioxide (SiO2 ), polydimethyl siloxane (PDMS) and porous methylsilsequioxane (p-MSQ) films. These methods include processing as a function of chamber wall temperature, chamber dimension, feedgas chemistry, and sample porosity while simultaneously measuring the plasma gas-phase chemistry, the plasma density, and the reactions which occur on the sample surface, to determine how each effects the plasma system as a whole. When processing as a function of chamber wall temperature, results in tetrafluoromethane plasma show that increasing wall temperature decreases CF4 density while concurrently increasing CF4 vibrational temperature. The line-averaged vibrational temperature however, was found to remain at a steady state value above the chamber wall temperature while the CF4 vibrational temperature in the center of the discharge was calculated to be significantly higher. Using a modified gaseous electronics conference (GEC) reference cell, chamber dimension was found to significantly effect the etch rate of silicon dioxide as well as the fluorocarbon deposition rate due to variations of ion density and neutral flux. Specifically, low-energy ion assisted deposition was found to be the predominant mechanism governing fluorocarbon deposition while ion loss as a function of dimension, was established to be the rate limiting step for high energy reactive ion etch. The role of feedgas chemistry on plasma-surface interactions was also explored and revealed how different ratios of O2:CF 4 gas mixtures can significantly modify the processing rates and sample surface chemistry of a hybrid polydimethylsiloxane material. Depending on the percentage of oxygen admixed in the tetrafluoromethane feedgas, the etch could be tailored from energy dependent to energy independent. Tweaking the process in an inductively coupled plasma further improved the etch rate such that it was twice as high as those published in a capacitive plasma process. The resultant stoichiometry of the etched films was also found to depend on the feedgas chemistry as the refractive index of the material increased by 7% when pure oxygen was used and decreased by 6% when pure tetrafluoromethane was used. (Abstract shortened by UMI.)

  19. Remote plasma processing of thin film materials

    NASA Astrophysics Data System (ADS)

    Kastenmeier, Bernd E. E.

    1999-09-01

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

  20. Plasma-assisted surface modification of biopolymers

    NASA Astrophysics Data System (ADS)

    Tajima, Satomi

    A wide range of polymers are used for cardiovascular devices. To improve hemocompatibility, polymer surface must be modified to resist thromboembolism formation. The polymer surface is non-polar and non-biocompatible in nature. In this study, the polymer surface was modified by plasma treatment followed by biocompatible film deposition and/or endothelial cell adhesion to improve hemocompatibility. Low-density polyethylene (LDPE) surfaces were first modified by downstream, inductively coupled, radio-frequency Ar plasma to improve the surface adhesion of blood-compatible films or endothelial cells. It was found that surface roughness, wettability, and subsurface crosslinking exhibited strong effects on surface adhesion. The extent of surface modification was controlled by varying the ion energy fluence, determined from the plasma ion density measured by a Langmuir probe. The plasma-treated LDPE surfaces were characterized by atomic force microscopy (AFM), contact angle measurements, X-ray photoelectron spectroscopy (XPS), and surface force microscopy (SFM). Nanoscale roughening, decrease in contact angle, carbon-oxygen functionalities, and formation of a high-density crosslinked layer occurred with the increase of the ion energy fluence up to 1.8 x 105 J/m2. In another series of experiments, capacitively coupled octafluorocyclobutane (c-C4F8) plasma was used to synthesize fluorocarbon films on Ar plasma-treated LDPE to improve blood compatibility. Films exhibiting low degrees of crosslinking, which is beneficial for resisting thromboembolism, were deposited by shielding the sample surface with a grounded metal plate, thus blocking the effects of ions and radiation and allowing only uncharged particles to interact with the polymer surface. In addition, endothelial cell adhesion onto Ar plasma-treated surfaces was examined as a means to further enhance blood compatibility. The adhesion and cytoskeleton morphology of endothelial cells attached onto Ar plasma-treated LDPE were evaluated and it was discovered that more cells adhered onto the hydrophilic surface produced by plasma treatment than the hydrophobic untreated surface. The cell spreading area increased with the increase of the surface wettability as a consequence of the increase of the ion energy fluence. This study demonstrated that both fluorocarbon films and endothelial cells can be successfully adhered and grown onto Ar plasma-treated LDPE surfaces. It was shown that treatment with inductively coupled Ar plasma is an effective surface-specific modification process which can provide tailored biochemical surface properties without altering the bulk properties.

  1. Efficient, environmentally acceptable method for waterproofing insulation material

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  2. Photochemical modification of polyethylene terephthalate surface

    NASA Astrophysics Data System (ADS)

    Zhu, Zhengmao

    The prospect of obtaining desired surface-mediated characteristics while retaining bulk-mediated physical properties and avoiding potential environmental issues with wet chemical technology lends considerable appeal to photochemical approaches to surface modification. We undertook a combined experimental and computational approach to investigate the effect of deep UV irradiation on the polyethylene terephthalate (PET) surface. Its response to 172 nm UV from a xenon examiner lamp in the absence of oxygen was characterized with X-ray Photoelectron Spectroscopy (XPS), Time of Flight/Secondary Ion Mass Spectrometry (ToF/SIMS), transmission infrared spectroscopy (IR), and Atomic Force Microscopy (AFM). The surface chemistry details suggested that the primary photochemical reactions involved a Norrish type I based decarbonylation and a Norrish type II process yielding terminal carboxylic acid groups, consistent with the possible photochemistry from n-pi* type lowest singlet excited states of PET according to the computational modeling results. By directly populating n-pi* type excited states, 172 nm UV promoted effective surface photochemistry of PET with further helps from the high UV absorptivity and the high surface mobility of the molecules. Utilizing this active surface radical chemistry, a new grafting strategy was developed to impart desirable functional properties to the surface. A broad range of grafting chemicals can be employed in their vapor forms, demonstrated with an alkene or an alkane. Surface analysis with XPS, ToF/SIMS, AFM, and water contact angle measurements confirmed the effectiveness of the approach, supporting the notion of the surface radical initiated processes. A potentially useful anti-stain/soil coating was developed by grafting with a fluorocarbon species. Surface analysis suggested that the grafted fluorocarbon formed a nano-scale self-assembled monolayer. The coating had a similar water contact angle as that of a pure fluoropolymer but a better oil repellency due to the special molecular orientation in the graft layer. A potential antimicrobial application was demonstrated with amine chemicals. Structure characterization and computational modeling results suggested that the photochemistry of the UV active grafting chemicals also played an important role in the grafting process. A double bond structure in the amine species protected the amine functional groups and the resulting coating demonstrated antimicrobial activity against E. coli.

  3. Multi-functional Textiles for Military Applications

    NASA Astrophysics Data System (ADS)

    Malshe, Priyadarshini

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

  4. Elucidation of atomic scale mechanisms for polytetrafluoroethylene tribology using molecular dynamics simulation

    NASA Astrophysics Data System (ADS)

    Barry, Peter R.

    Polytetrafluoroethylene (PTFE) is a polymer that has been widely exploited commercially as a result of its low friction, 'non-stick' properties. The polymer has found usage as 'non-stick,' chemically resistant coatings for bearings, valves, rollers and pipe linings with applications in industries ranging from food and chemical processing to construction, automotive and aerospace. The major drawback of PTFE in low friction applications involves its excessive wear rate. For decades, scientists and engineers have sought to improve the polymer's wear resistance while maintaining its low sliding friction by reinforcing the polymer matrix with a host of filler materials ranging from fibril to particulate. In this study, a different approach is taken in which the atomic scale phenomena between two crystalline PTFE surfaces in sliding contact are examined. The goal is to obtain atomic-level insights into PTFE's low friction and high wear rate to aid in the designing of effective polymer based tribological composites for extreme condition applications. To accomplish this, several tribological conditions were varied. These included sliding direction of the two polymer surfaces with respect to their chain alignment, sliding velocity, degree of crystalline phase rigidity, interfacial contact pressure, sample temperature and the presence of fluorocarbon fluids between the two crystalline PTFE surfaces. From these studies, it was found that crystalline PTFE-PTFE sliding demonstrates friction anisotropy. Low friction and molecular wear was observed when sliding in the direction of the chain alignment with high friction and wear behavior dominating when sliding in a direction perpendicular to the chain alignment. For the range of cross-link density (average linear density of 6.2 to 11.1 A) and sliding rate (5 m/s to 20 m/s) explored, a significant change in friction behavior or wear mechanisms was not observed. Under conditions of increased normal load or low temperature however, the frictional force increased linearly. Additionally, the inclusion of fluorocarbon molecular fluids at the sliding interface between the two crystalline PTFE surfaces resulted in a significant decrease in both the friction and wear of the surfaces.

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

    SciTech Connect

    Shoeb, Juline; Kushner, Mark J. [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

    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.

  6. Calibration and Sequence Development Status for the Sample Analysis at Mars Investigation on the Mars Science Laboratory

    NASA Technical Reports Server (NTRS)

    Mahaffy, Paul R.

    2012-01-01

    The measurement goals of the Sample Analysis at Mars (SAM) instrument suite on the "Curiosity" Rover of the Mars Science Laboratory (MSL) include chemical and isotopic analysis of organic and inorganic volatiles for both atmospheric and solid samples [1,2]. SAM directly supports the ambitious goals of the MSL mission to provide a quantitative assessment of habitability and preservation in Gale crater by means of a range of chemical and geological measurements [3]. The SAM FM combined calibration and environmental testing took place primarily in 2010 with a limited set of tests implemented after integration into the rover in January 2011. The scope of SAM FM testing was limited both to preserve SAM consumables such as life time of its electromechanical elements and to minimize the level of terrestrial contamination in the SAM instrument. A more comprehensive calibration of a SAM-like suite of instruments will be implemented in 2012 with calibration runs planned for the SAM testbed. The SAM Testbed is nearly identical to the SAM FM and operates in a ambient pressure chamber. The SAM Instrument Suite: SAM's instruments are a Quadrupole Mass Spectrometer (QMS), a 6-column Gas Chromatograph (GC), and a 2-channel Tunable Laser Spectrometer (TLS). Gas Chromatography Mass Spectrometry is designed for identification of even trace organic compounds. The TLS [5] secures the C, H, and O isotopic composition in carbon dioxide, water, and methane. Sieved materials are delivered from the MSL sample acquisition and processing system to one of68 cups of the Sample Manipulation System (SMS). 59 of these cups are fabricated from inert quartz. After sample delivery, a cup is inserted into one of 2 ovens for evolved gas analysis (EGA ambient to >9500C) by the QMS and TLS. A portion of the gas released can be trapped and subsequently analyzed by GCMS. Nine sealed cups contain liquid solvents and chemical derivatization or thermochemolysis agents to extract and transform polar molecules such as amino acids, nucleobases, and carboxylic acids into compounds that are sufficiently volatile to transmit through the GC columns. The remaining 6 cups contain calibrants. SAM FM Calibration Overview: The SAM FM calibration in the Mars chamber employed a variety of pure gases, gas mixtures, and solid materials. Isotope calibration runs for the TLS utilized 13C enriched C02 standards and 0 enriched CH4. A variety of fluorocarbon compounds that spanned the entire mass range of the QMS as well as C3-C6 hydrocarbons were utilized for calibration of the GCMS. Solid samples consisting of a mixture of calcite, melanterite, and inert silica glass either doped or not with fluorocarbons were introduced into the SAM FM cups through the SAM inlet funnel/tube system.

  7. Plasma deposited stability enhancement coating for amorphous ketoprofen.

    PubMed

    Bosselmann, Stephanie; Owens, Donald E; Kennedy, Rachel L; Herpin, Matthew J; Williams, Robert O

    2011-05-01

    A hydrophobic fluorocarbon coating deposited onto amorphous ketoprofen via pulsed plasma-enhanced chemical vapor deposition (PPECVD) significantly prolonged the onset of recrystallization compared to uncoated drug. Rapid freezing (RF) employed to produce amorphous ketoprofen was followed by PPECVD of perfluorohexane. The effect of coating thickness on the recrystallization and dissolution behavior of ketoprofen was investigated. Samples were stored in open containers at 40°C and 75% relative humidity, and the onset of recrystallization was monitored by DSC. An increase in coating thickness provided enhanced stability against recrystallization for up to 6 months at accelerated storage conditions (longest time of observation) when compared to three days for uncoated ketoprofen. Results from XPS analysis demonstrated that an increase in coating thickness was associated with improved surface coverage thus enabling superior protection. Dissolution testing showed that at least 80% of ketoprofen was released in buffer pH 6.8 from all coated samples. Overall, an increase in coating thickness resulted in a more complete drug release due to decreased adhesion of the coating to the substrate. PMID:21167280

  8. Surface-catalyzed air oxidation of hydrazines: Environmental chamber studies

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  9. Nonflammable, Nonaqueous, Low Atmospheric Impact, High Performance Cleaning Solvents

    NASA Technical Reports Server (NTRS)

    Dhooge, P. M.; Glass, S. M.; Nimitz, J. S.

    2001-01-01

    For many years, chlorofluorocarbon (CFC) and chlorocarbon solvents have played an important part in aerospace operations. These solvents found extensive use as cleaning and analysis (EPA) solvents in precision and critical cleaning. However, CFCs and chlorocarbon solvents have deleterious effects on the ozone layer, are relatively strong greenhouse gases, and some are suspect or known carcinogens. Because of their ozone-depletion potential (ODP), the Montreal Protocol and its amendments, as well as other environmental regulations, have resulted in the phaseout of CFC-113 and 1,1,1-trichloroethane (TCA). Although alternatives have been recommended, they do not perform as well as the original solvents. In addition, some analyses, such as the infrared analysis of extracted hydrocarbons, cannot be performed with the substitute solvents that contain C-H bonds. CFC-113 solvent has been used for many critical aerospace applications. CFC-113, also known as Freon (registered) TF, has been used extensively in NASA's cleaning facilities for precision and critical cleaning, in particular the final rinsing in Class 100 areas, with gas chromatography analysis of rinse residue. While some cleaning can be accomplished by other processes, there are certain critical applications where CFC-113 or a similar solvent is highly cost-effective and ensures safety. Oxygen system components are one example where a solvent compatible with oxygen and capable of removing fluorocarbon grease is needed. Electronic components and precision mechanical components can also be damaged by aggressive cleaning solvents.

  10. Equipment and design changes in extrusion of foamed fluoropolymer resins

    NASA Astrophysics Data System (ADS)

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

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

  11. Formation of fluorinated nonionic surfactant microemulsions in hydrofluorocarbon 134a (HFC 134a).

    PubMed

    Patel, Nilesh; Marlow, Maria; Lawrence, M Jayne

    2003-02-15

    A structurally related series of fluorinated nonionic oxyethylene glycol surfactants of the type C(m)F(2m+1)(CH(2))(n)O[(CH(2)CH(2)O)(p)H], denoted C(m.n)E(p) (where m=4, 6, or 7, m=1 or 2, and p=4 or 6) were synthesized and their surface behavior in aqueous solution was characterized. The ability of these surfactants to form water-in-hydrofluorocarbon (HFC) propellant 134a microemulsions suitable for use in the aerosolized delivery of water-soluble drugs has been investigated. Phase studies showed that, regardless of the composition used, clear one-phase systems could not be prepared if a fluorinated nonionic surfactant was used alone, or in combination with a short or medium fluorocarbon alcohol cosurfactant. Clear one-phase systems could, however, be prepared if a short-chain hydrocarbon alcohol, such as ethanol, n-propanol, or n-pentanol, was used as cosurfactant, with the extent of the one-phase region increasing with decreased chain length of the alcohol cosurfactant. Light-scattering studies on a number of the hydrocarbon-alcoholcontaining systems in the propellant-rich part of the phase diagram showed that only systems prepared with C(4.2)E(6) and propanol contained microemulsion droplets (all other systems investigated were considered to be cosolvent systems). PMID:12618104

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

    PubMed Central

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

    2014-01-01

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

  13. Structures and properties of fluorinated amorphous carbon films

    NASA Astrophysics Data System (ADS)

    Huang, K. P.; Lin, P.; Shih, H. C.

    2004-07-01

    Fluorinated amorphous carbon (a-C:F) films were deposited by radio frequency bias assisted microwave plasma electron cyclotron resonance chemical vapor deposition with tetrafluoromethane (CF4) and acetylene (C2H2) as precursors. The deposition process was performed at two flow ratios R=0.90 and R=0.97, where R=CF4/(CF4+C2H2). The samples were annealed at 300 °C for 30 min. in a N2 atmosphere. Both Fourier transform infrared and electron spectroscopy for chemical analyzer were used to characterize the a-C:F film chemical bond and fluorine concentration, respectively. A high resolution electron energy loss spectrometer was applied to detect the electronic structure. The higher CF4 flow ratio (R=0.97) produced more sp3 linear structure, and it made the a-C:F film smoother and softer. A lifetime of around 0.34 ?s and an energy gap of ˜2.75 eV were observed in both the as-deposited and after annealing conditions. The short carriers lifetime in the a-C:F film made the photoluminescence peak blueshift. The annealing changed both the structure and composition of the a-C:F film. The type of fluorocarbon bond and electronic structure characterized the mechanical and physical properties of a-C:F film.

  14. Possible greenhouse effects of tetrafluoromethane and carbon dioxide emitted from aluminum production

    NASA Astrophysics Data System (ADS)

    Weston, Ralph E.

    Tetrafluoromethane (CF 4) is an extremely stable gas which strongly absorbs infrared radiation at ˜ 8 ?m, and therefore is capable of influencing the greenhouse effect. No natural sources have been identified, and the major anthropogenic source appears to be the electrolytic smelting of alumina to produce aluminum. Measurements of CF 4 concentrations in the atmosphere are reviewed, and these are combined with aluminum production rates to provide an estimate of 1.3-3.6 kg of CF 4 emitted per ton of aluminum produced for the period up to ˜ 1985. Aluminum production also requires large amounts of electrical energy, leading to the emission of as much as 22 tons of carbon dioxide per ton of aluminum due to fossil fuel combustion in power plants. The present day contribution of hydroelectric power reduces this figure to about 14 tons of carbon dioxide per ton of aluminum. An estimate of the relative radiative trapping of CF 4 and CO 2 emitted in aluminum production during this same period (1900-1985) indicates that the effect of CF 4 is about one-third that of the CO 2 formed by aluminum production. However, the emission of fluorocarbons from modem aluminum electrolysis cells is much lower than previous estimates indicate, and this factor is considered in estimating potential long-term global warming effects of CF 4 and CO 2 from aluminum production. Possible processes leading to removal of CF 4 from the atmosphere are described.

  15. 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)

    Hassan, Razi A.

    1991-01-01

    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.

  16. Mitigating molecular and particulate contamination via surface energy

    NASA Astrophysics Data System (ADS)

    Crowder, Mark S.; Haley, Christina

    2008-08-01

    Amorphous fluorocarbon (a-C:F) thin films have been developed that protect surfaces from molecular and particulate contamination. The surface energies of the thin films are low and primarily dispersive in origin with values of energies measured to be as low as 18 mJ/m2 (17.5 dispersive, 0.5 polar). The films are transparent to visible light and have a refractive index of ~1.4. The a-C:F surface energy was found to be thermally stable when exposed to temperatures that range from 77°K to 400°C. Molecular absorption rates are significantly reduced on gold surfaces when over-coated with an a-C:F thin film. The adhesion force of particles to the a-C:F surface is low and can dramatically decrease the susceptibility of particles to adhere to surfaces over-coated with the thin film. The robust nature of the diamond-like thin films make them candidates for protecting aerospace surfaces, such as optical surfaces, from contamination.

  17. High performance organic field-effect transistors with fluoropolymer gate dielectric

    NASA Astrophysics Data System (ADS)

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

    2007-09-01

    Electrical stability is essential for a successful commercialization of organic semiconductor devices. We report on organic field-effect transistors with unprecedented electrical stability. The single crystal and thin-film transistors employ a fluorocarbon polymer as gate dielectric (Cytop TM) and pentacene or rubrene as the organic semiconductor. Cytop TM (Cyclic Transparent Optical Polymer) is easy to be used and can be deposited in air from solution. It is highly hydrophobic and has a very low permittivity of ? i = 2.1 - 2.2. Moreover, the material is a good electrical insulator with a very high dielectric breakdown field. Its passive surface leads to extremely stable field-effect transistors with a high field-effect mobility, an outstanding subthreshold swing as low as 0.75 nFV/(decade cm2) and a near zero onset voltage. Of particular significance is the resistance of the devices against long-term gate bias stress. Oligomeric organic semiconductors can have a very high electrical stability when combined with a suitable gate dielectric. Cytop TM is an ideal gate dielectric for organic electronics and it seems very likely that the material leads to outstanding transistors in combination with many small molecule organic semiconductors.

  18. STRUCTURE OF TYPE 5 ADENOVIRUS

    PubMed Central

    Wilcox, Wesley C.; Ginsberg, Harold S.

    1963-01-01

    Type 5 adenovirus was purified by fluorocarbon (freon 113) treatment followed by banding in a CsCl equilibrium density gradient. This method permitted separation of virus from normal host cell materials and virus-specific soluble antigens. Virus banded in CsCl with a mean bouyant density of 1.3349 gm/cm3. The three virus-specific soluble antigens (group- and type-specific antigens and toxin) banded together with a mean bouyant density of 1.2832 gm/cm3. The group-specific antigen was the predominant antigen of the purified virus particle, whereas the group- and type-specific antigens were present in equal titers in the antigen band. Infectious virus particles were inactivated by prolonged dialysis at pH 10.5. Centrifugation of inactivated virus preparations in a CsCl equilibrium density gradient resulted in separation of virus DNA from specific antigen: the antigens banded with a mean bouyant density of 1.2832 gm/cm3 and the DNA sedimented to the bottom of the tube. The predominant antigen derived from purified virus particles was the group-specific antigen and it was in the same relative proportion to the type-specific antigen as measured in intact particles. The antigens derived from disrupted virus were immunologically identical with the soluble virus antigens present in infected cells. PMID:14074393

  19. Is there any chlorine monoxide in the stratosphere?

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    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.

  20. The evolution of spatial ordering of oil drops fast spreading on a water surface

    PubMed Central

    Yamamoto, Daigo; Nakajima, Chika; Shioi, Akihisa; Krafft, Marie Pierre; Yoshikawa, Kenichi

    2015-01-01

    The design of dynamically self-assembled systems is of high interest in science and technology. Here, we report a unique cascade in the self-ordering of droplets accompanied by a dewetting transition. The dynamic self-emergent droplets are observed when a thin liquid layer of an immiscible fluorocarbon oil (perfluorooctyl bromide, PFOB) is placed on a water surface. Due to the gradual evaporation of PFOB, a circular PFOB-free domain appears as a result of a local dewetting transition. A circular pearling structure is generated at the rim with the growth of the dewetting hole. As the next stage, linear arrays of droplets are generated in a radial manner from the centre of the hole. These one-dimensional arrangements then evolve into two-dimensional hexagonal arrays of microdroplets through collective rhythmical shrinking/expanding motions. The emergence of such dynamic patterns is discussed in terms of the nonlinear kinetics of the dewetting transition under thermodynamically dissipative conditions. PMID:25998157

  1. Correlation of refrigerant mass flow rate through adiabatic capillary tubes using mixture refrigerant carbondioxide and ethane for low temperature applications

    NASA Astrophysics Data System (ADS)

    Nasruddin, Syaka, Darwin R. B.; Alhamid, M. Idrus

    2012-06-01

    Various binary mixtures of carbon dioxide and hydrocarbons, especially propane or ethane, as alternative natural refrigerants to Chlorofluorocarbons (CFCs) or Hydro fluorocarbons (HFCs) are presented in this paper. Their environmental performance is friendly, with an ozone depletion potential (ODP) of zero and Global-warming potential (GWP) smaller than 20. The capillary tube performance for the alternative refrigerant HFC HCand mixed refrigerants have been widely studied. However, studies that discuss the performance of the capillary tube to a mixture of natural refrigerants, in particular a mixture of azeotrope carbon dioxide and ethane is still undeveloped. A method of empirical correlation to determine the mass flow rate and pipe length has an important role in the design of the capillary tube for industrial refrigeration. Based on the variables that effect the rate of mass flow of refrigerant in the capillary tube, the Buckingham Pi theorem formulated eight non-dimensional parameters to be developed into an empirical equations correlation. Furthermore, non-linear regression analysis used to determine the co-efficiency and exponent of this empirical correlation based on experimental verification of the results database.

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

    PubMed

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

    2009-01-01

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

  3. Calcification of intraocular implant lens surfaces.

    PubMed

    Wu, Wenju; Guan, Xiangying; Tang, Ruikang; Hook, Daniel; Yan, Wenyan; Grobe, George; Nancollas, George H

    2004-02-17

    Calcification of octacalcium phosphate [Ca8H2(PO4)6 x 5H2O, OCP] on differently packaged "Ultem" and "Surefold" intraocular implant lens surfaces has been studied in vitro in solutions supersaturated with respect to OCP at pH = 7.10 and 37 degrees C. No mineral deposition was observed on the lenses packaged in Ultem vials even after treatment with behenic acid, one of the fatty acids identified on explanted lenses. Following treatment with behenic acid, nucleation of OCP occurred on the lenses from Surefold vials, which incorporate silicone gaskets; induction periods preceding calcification were about 6 h. No mineralization was found on the lenses in vials with other gasket materials, including polytetrafluoroethylene, fluorocarbon elastomer, and polypropylene. The results of this study indicate that both silicone and fatty acids such as behenic acid play important roles in inducing the in vivo calcification of OCP on IOL lenses; all of the lens treatment steps were necessary for nucleation induction. PMID:15803719

  4. Mechanisms of oxygen plasma nanotexturing of organic polymer surfaces: from stable super hydrophilic to super hydrophobic surfaces.

    PubMed

    Tsougeni, K; Vourdas, N; Tserepi, A; Gogolides, E; Cardinaud, C

    2009-10-01

    Plasma processing is used to fabricate super hydrophilic or super hydrophobic polymeric surfaces by means of O2 plasma etching of two organic polymers, namely, poly(methyl methacrylate) (PMMA) and poly(ether ether ketone) (PEEK); a C4F8 plasma deposition follows O2 plasma etching, if surface hydrophobization is desired. We demonstrate high aspect ratio pillars with height ranging from 16 nm to several micrometers depending on the processing time, and contact angle (CA) close to 0 degrees after O2-plasma treatment or CA of 153 degrees (with CA hysteresis lower than 5 degrees) after fluorocarbon deposition. Super hydrophobic surfaces are robust and stable in time; in addition, aging of super hydrophilic surfaces is significantly retarded because of the beneficial effect of the nanotextured topography. The mechanisms responsible for the plasma-induced PMMA and PEEK surface nanotexturing are unveiled through intelligent experiments involving intentional modification of the reactor wall material and X-ray photoelectron spectroscopy, which is also used to study the surface chemical modification in the plasma. We prove that control of plasma nanotexture can be achieved by carefully choosing the reactor wall material. PMID:19788226

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

    PubMed

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

    2014-07-21

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

  6. Erythropoietic response to acute anemia.

    PubMed

    Rosen, A L; Gould, S A; Sehgal, L R; Levine, E A; Sehgal, H L; Goldwasser, E; Beaver, C W; Moss, G S

    1990-03-01

    Reliance on a brisk erythropoietic response to untreated blood loss is an alternative to transfusion of homologous blood. Slow erythropoiesis has been observed in ICU patients who refused blood. Many of these patients received supplemental oxygen therapy and Fluosol-DA, a temporary red cell substitute. This study reports the erythropoietic response, in the baboon, to moderate (Hct 20%) and severe (Hct 10%) anemia. In addition, the effect of oxygen therapy (FIO2 0.6 for 1 wk) and fluorocarbon emulsions (Oxypherol) on erythropoiesis was evaluated. Baboons uniformly survived acute normovolemic anemia with Hct 10%. In all cases, the response to anemia was characterized by a lag period (with no change in Hct), and a nonlinear recovery period. A lag period of 3 days was observed in both moderate and severe anemia for baboons breathing room air or FIO2 0.6. The lag period was prolonged to 1 wk in the presence of Oxypherol. The recovery period exhibited a uniform and negative correlation between the rate of Hct change and the Hct, in all cases. The theoretical maximum rate of increase of Hct was 2.6%/day. In untreated blood loss, shortening the lag period and increasing the slope of the recovery period will decrease the length of time that the patient is anemic. PMID:1689236

  7. Midwestern efforts to address climate change

    SciTech Connect

    Daniel Stenberg [Midwestern Governors Association (United States)

    2008-12-15

    Six Midwestern governors and a Canadian premier signed the Midwestern Greenhouse Gas Reduction Accord in November 2007. The governors agreed to begin the process of developing a market-based cap-and-trade program that would reduce GHG emissions (e.g., carbon dioxide, methane, nitrous oxide, hydro-fluorocarbons, perfluorocarbons, and sulfur hexafluoride) to meet reduction targets. Member jurisdictions include Illinois, Iowa, Kansas, Manitoba, Michigan, Minnesota, and Wisconsin. Observer jurisdictions - those who are participating in the program design, but will decide later whether to be full members-include Indiana, Ohio, Ontario, and South Dakota. To date, the advisory group has proposed target ranges for GHG emissions reductions of 15-25% below 2005 levels by 2020 and 60-80% by 2050. The following sectors are currently being considered for the cap-and-trade program: electricity generation and imports (power plants); industrial combustion sources (factories and other industrial facilities); and industrial process sources (to the extent credible measurement and monitoring protocols exist or can be developed prior to inclusion).

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

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

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

  10. Volatile substance misuse: an updated review of toxicity and treatment.

    PubMed

    Ford, Jonathan B; Sutter, Mark E; Owen, Kelly P; Albertson, Timothy E

    2014-02-01

    Educational campaigns and legislative actions may have led to an overall decrease in the prevalence of volatile substance misuse (VSM) in many countries; however, it is still a common practice throughout the world. Studies currently suggest that girls are misusing volatile substances more than before and at a prevalence rate equal to or exceeding that of boys in several countries. Products that may be misused are ubiquitous and relatively easy to acquire. The most commonly misused substances in recent studies are fuels such as butane or petrol and compressed gas dusters and deodorants that may contain fluorocarbons and/or butane. Detection of VSM is challenging, therefore physicians must maintain a high level of suspicion based on history and clinical presentation. Clues to misuse are often subtle and may include the patient's proximity to a volatile substance or paraphernalia when found intoxicated, dermal burns, blisters, pigments, or rashes, and chemical odors. The primary targets of toxicity are the brain and the heart. The leading cause of death from VSM is from ventricular dysrhythmias. Treatment of toxicity begins with support of airway, breathing, and circulation. Exogenous catecholamines should be avoided if possible due to the theoretical "sensitized" and irritable myocardium. In the case of ventricular dysrhythmias, direct current defibrillation and/or beta-adrenergic receptor antagonism should be used. New evidence demonstrates the addictive potential of VSM yet effective therapy remains uncertain. Further research is needed in developing methods for preventing, detecting, and treating the harmful effects of VSM. PMID:23649409

  11. Laboratory studies of chemical and photochemical processes relevant to stratospheric ozone

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    The purpose of this project is to reduce the uncertainty in several key gas-phase kinetic processes which impact our understanding of stratospheric ozone. The main emphasis of this work is on measuring rate coefficients and product channels for reactions of HO(sub x) and NO(sub x) species in the temperature range 200 K to 240 K relevant to the lower stratosphere. Other areas of study have included infrared spectroscopic studies of the HO2 radical, measurements of OH radical reactions with alternative fluorocarbons, and determination of the vapor pressures of nitric acid hydrates under stratospheric conditions. The results of these studies will improve models of stratospheric ozone chemistry and predictions of perturbations due to human influences. In this annual report, we focus on our recent accomplishments in the quantitative spectroscopy of the HO2 radical. This report details the measurements of the broadening coefficients for the v(sub 2) vibrational band. Further measurements of the vapor pressures of nitric acid hydrates relevant to the polar stratospheric cloud formation indicate the importance of metastable crystalline phases of H2SO4, HNO3, and H2O. Large particles produced from these metastable phases may provide a removal mechanism for HNO3 in the polar stratosphere.

  12. Gene expression during S. epidermidis biofilm formation on biomaterials.

    PubMed

    Patel, Jasmine D; Colton, Erica; Ebert, Michael; Anderson, James M

    2012-11-01

    Biomaterial-centered infections are initiated by adhesion of bacteria to an implant, followed by colonization and mature biofilm formation. Staphylococcus epidermidis is commonly identified as the cause of these device-centered infections. This study used an in vitro model to evaluate temporal changes in the expression of genes-icaADBC, agrBDCA, aap, and atle-that have been identified to play a role in the pathogenesis of S. epidermidis infections. Real-time reverse transcription-polymerase chain reaction was used to determine changes in gene expression from S epidermidis biofilm grown on polyurethanes (Elasthane 80A, hydrophobic) modified with polyethylene oxide (Elasthane 80A-6PEO, hydrophilic) and fluorocarbon (Elasthane 80A-6F, hydrophobic). In vitro expression of the ica locus, which is involved in initial adhesion and intracellular aggregation, increased up to 100-fold from 2 to 48 h, whereas gene expression for autolysin AtlE decreased slightly from 2 to 12 h, followed by a 10-fold increase by 48 h. Upregulation of the aap gene associated with bacterial accumulation and the agr quorum-sensing system was observed during biofilm formation over 48 h. In addition, no correlation was observed between S. epidermidis gene expression and biomaterial surface chemistry. This study used an in vitro model to demonstrate that enhanced expression of the atle, aap, agr, and ica genes plays an important role in initial foreign body colonization and potentially in the establishment of a device-associated infection. PMID:22623350

  13. In situ measurement of the bonded film thickness of Z-Tetraol lubricant on magnetic recording media

    NASA Astrophysics Data System (ADS)

    Zhu, Lei; Li, Feng

    2010-10-01

    Currently, the bonded film thickness of perfluoropolyether lubricant on top of magnetic recording media is measured by a two-step process. First, the media disk has to be rinsed thoroughly using a fluorocarbon solvent (for instance, Vetrel) to remove the mobile lubricant. Second, the thickness of the remaining lubricant on the media surface which is regarded as the bonded lubricant thickness is then measured either by Fourier transform infrared spectroscopy (FTIR) or electron spectroscopy for chemical analysis. As the total lubricant thickness approaches single molecular dimension (˜10 Å), current methods face tremendous challenge on the accuracy and sensitivity of the measurement. We studied the spectral characteristics responding to the lubricant bonding with the carbon overcoat by the time-of-flight secondary ion mass spectra and proposed to use the peak area ratio (C3H2F/C3H5O and C4H10O/C3H6O2) to characterize the bonded Z-Tetraol lubricant that produces a direct bonded lubricant thickness measurement without the need to remove the mobile lubricant with a solvent. After taking the background signal of disks prior to bonding by UV irradiation into account, this method becomes independent of the total lubricant thickness as well as shows good correlation linearity (R2˜87%) with the current FTIR method for the ratio of C4H10O/C3H6O2.

  14. Substrate and chain length dependencies of the thermal behavior of [CF3(CF2)m(CH2)nCOO]2Cd single monolayers investigated by infrared reflection absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Ren, Yanzhi; Asanuma, Morito; Iimura, Ken-ichi; Kato, Teiji

    2001-01-01

    Temperature-variable grazing incidence reflection absorption (GIR) spectra were recorded for the single monolayer of [CF3(CF2)m(CH2)nCOO)]2Cd [(m,n)=(7,10), (7,16), (7,22), (5,22), and (3,22)], transferred from aqueous Cd2+ subphase to gold- and aluminum-evaporated glass substrates. The spectra reveal that these monolayers have better thermal stability on Al substrates than on Au. An "interaction band" is identified at 1484˜1480 cm-1, due to the ?s(COO-) mode of carboxylate headgroups in ionic bonding with the Al surface. It is found that both the van der Waals interaction between the trans zig-zag hydrocarbon chains and the overlapping interaction between the fluorocarbon helixes are responsible for the systematic variation of the monolayer thermal behavior with (m,n). The thermal behavior of a single monolayer of cadmium stearate, serving as a model system, has been investigated to further confirm the spectral interpretation about the partially fluorinated monolayer. In addition, temperature-dependent friction measurements show that the single monolayers of (m,n)=(7,16), (7,22), (5,22), and (3,22) are potential molecular lubricants that can be used in the range of 25˜140 °C.

  15. Deposition of Wave-shaped Layered Low-k Dielectric a-C:F Films by C8F18 Plasma CVD

    NASA Astrophysics Data System (ADS)

    Mizuno, Kouichiro; Sugawara, Hirotake; Murayama, Akihiro

    We have composed amorphous fluorocarbon (a-C:F) polymer films, which are low-k insulators, by plasma-enhanced chemical vapor deposition using C8F18 as the feedstock. In our previous attempts to form multi-layered a-C:F films under various combinations of plasma power density P and deposition time T, it was found that a-C:F films deposited at a high P (typically 2.0 W/cm3) in a short T (?1 min) became wavy when they are deposited on other a-C:F films deposited at a low P (0.2 W/cm3). A heating experiment for the films showed that their thermal tolerance was dependent on P films deposited at 0.2 W/cm3 started to melt at 250-270°C, while those deposited at 2.0 W/cm3 did at 350-370°C. It is considered that species of the precursors for the a-C:F film deposition are determined by P through the degree of C8F18 decomposition. The waving is induced by heating the lower layer during the deposition of the upper layer. The following conditions are necessary for the waving; the lower layer is deposited at a low P, the upper layer is deposited at a temperature at which the lower layer expands but does not melt, and the upper layer is not thickened excessively to keep its flexibility.

  16. Liquid-film stripper for high-intensity heavy-ion beams

    SciTech Connect

    Leemann, B.T.; Merrill, P.; Syversrud, H.K.; Wada, R.; Yourd, R.B.

    1981-03-01

    Electron strippers are widely used in heavy ion accelerators such as tandem Van de Graaff generators and heavy ion linacs. The SuperHILAC at Lawrence Berkeley Laboratory, employs a fluorocarbon oil vapor stripper at 113 keV/A for its high intensity injector ABEL, while after acceleration to 1.199 MeV/A a 35 ..mu..g/cm/sup 2/ carbon foil stripper is used. At present, the lifetime of these foils is about 1 hour for an /sup 40/Ar beam of approx. 1 ..mu..A average particle current. With higher intensity high mass (100 less than or equal to A less than or equal to 238) beams available from ABEL injector the lifetime is expected to drop drastically and might be as low as one minute. A different approach to solve the stripper foil lifetime problem uses a thin free standing oil film spun from the edge of a sharp-edged rotating disc touching the surface of an oil reservoir. Areas of about 10 cm/sup 2/ with areal densities down to 20 ..mu..g/cm/sup 2/ have been reported. The work described here is based on the same concept, and produces a constantly regenerated, stable, free standing oil film of appropriate thickness for use at the SuperHILAC.

  17. Ab Initio Study of Hydration and Proton Dissociation in Ionomer Membranes

    SciTech Connect

    Idupulapati, Nagesh B.; Devanathan, Ramaswami; Dupuis, Michel

    2010-07-01

    We present a comparative study of proton dissociation in various functional acidic units that are promising candidates as building blocks for polymeric electrolyte membranes. Minimum energy structures for four acidic moieties with clusters of 1-6 water molecules were determined using density functional theory at the B3LYP/6-311G** level starting from chemically rational initial configurations. The perfluoro sulfonyl imide acid group (CF3CF2SO2NHSO2CF3) was observed to be the strongest acid, due to the substantial electron withdrawing effect of both fluorocarbon groups. The hydrophilic functional group (CH3OC6H3OCH3C6H4SO3H) of sulfonated polyetherether ketone (SPEEK) membrane was found to be the strongest base with the acidic proton dissociation requiring the addition of six water molecules and the hydrated proton being more tightly bound to the conjugate base. Even though both perfluoro sulfonyl imides and sulfonic acids (hydrophilic functional groups for sulfonyl imide and Nafion ionomers respectively) required only three water molecules to exhibit spontaneous proton dissociation, the largest possible solvent-separated hydronium ion was attained only for the sulfonyl imide moiety. These results provide a scientific basis for understanding the improved conductivity of perfluorinated sulfonyl imide-based membranes relative to that of the widely-used Nafion membrane.

  18. Fabrication of "roll-off" and "sticky" superhydrophobic cellulose surfaces via plasma processing.

    PubMed

    Balu, Balamurali; Breedveld, Victor; Hess, Dennis W

    2008-05-01

    Most of the artificial superhydrophobic surfaces that have been fabricated to date are not biodegradable, renewable, or mechanically flexible and are often expensive, which limits their potential applications. In contrast, cellulose, a biodegradable, renewable, flexible, inexpensive, biopolymer which is abundantly present in nature, satisfies all the above requirements, but it is not superhydrophobic. Superhydrophobicity on cellulose paper was obtained by domain-selective etching of amorphous portions of the cellulose in an oxygen plasma and subsequently coating the etched surface with a thin fluorocarbon film deposited via plasma-enhanced chemical vapor deposition using pentafluoroethane as a precursor. Variation of plasma treatment yielded two types of superhydrophobicity : "roll-off" (contact angle (CA), 166.7 degrees +/- 0.9 degrees ; CA hysteresis, 3.4 degrees +/- 0.1 degrees ) and "sticky" (CA, 144.8 degrees +/- 5.7 degrees ; CA hysteresis, 79.1 degrees +/- 15.8 degrees ) near superhydrophobicity. The nanometer scale roughness obtained by delineating the internal roughness of each fiber and the micrometer scale roughness which is inherent to a cellulose paper surface are robust when compared to roughened structures created by traditional polymer grafting, nanoparticle deposition, or other artificial means. PMID:18315020

  19. Influence of sexual dimorphism on pulmonary inflammatory response in adult mice exposed to chloroform.

    PubMed

    Oliveira, Túlio Henrique Versiani de; Campos, Keila Karine Duarte; Soares, Nícia Pedreira; Pena, Karina Braga; Lima, Wanderson Geraldo; Bezerra, Frank Silva

    2015-05-01

    Chloroform is an organic solvent used as an intermediate in the synthesis of various fluorocarbons. Despite its widespread use in industry and agriculture, exposure to chloroform can cause illnesses such as cancer, especially in the liver and kidneys. The aim of the study was to analyze the effects of chloroform on redox imbalance and pulmonary inflammatory response in adult C57BL/6 mice. Forty animals were divided into 4 groups (N = 10): female (FCG) and male (MCG) controls, and females (FEG) and males (MEG) exposed to chloroform (7.0 ppm) 3 times/d for 20 minutes for 5 days. Total and differential cell counts, oxidative damage analysis, and protein carbonyl and antioxidant enzyme catalase (CAT) activity measurements were performed. Morphometric analyses included alveolar area (Aa) and volume density of alveolar septa (Vv) measurements. Compared to FCG and MCG, inflammatory cell influx, oxidative damage to lipids and proteins, and CAT activity were higher in FEG and MEG, respectively. Oxidative damage and enzyme CAT activity were higher in FEG than in FCG. The Aa was higher in FEG and MEG than in FCG and MCG, respectively. The Vv was lower in FEG and MEG than in FCG and MCG, respectively. This study highlights the risks of occupational chloroform exposure at low concentrations and the intensity of oxidative damage related to gender. The results validate a model of acute exposure that provides cellular and biochemical data through short-term exposure to chloroform. PMID:25870144

  20. Characterization of Inductively Coupled Discharges in C2F6 and CHF3

    NASA Astrophysics Data System (ADS)

    Hebner, Greg

    1999-10-01

    The chloro-fluorocarbon gases C2F6 and CHF3 are used in a number of microelectronic plasma processing systems for both oxide etch and surface passivation. To provide data on the fundamental plasma characteristics as well as plasma species, microwave interferometry has been used to measure the line integrated electron density, photodetachment spectroscopy was used to measure the negative ion density, and laser induced fluorescence (LIF) was used to measure the spatially resolved CF density. The measurements were performed in a GEC rf reference chamber with an inductive coil plasma source and rf wafer bias. Photodetachment measurements of the negative ions as a function of wavelength are consistent with the dominant negative ion being F-. Different trends between the negative ion density and the electron density show that the negative ion precursor species density depends on power, pressure and rf wafer bias, but not on the feed gas. By pulse modulating the plasma power, negative ion - positive ion recombination rates have been determined. Spatially resolved LIF measurements show the CF density peaking in the center of the C2F6 discharge but a more uniform radial distribution in CHF3. CF density scaling with power, pressure, rf bias and surface material will be shown. This work was performed at Sandia National Laboratories and supported by SEMATECH and the United States Department of Energy (DE-AC04-94AL85000).

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

    SciTech Connect

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

    2005-11-15

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

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

    SciTech Connect

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

    2013-05-15

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

  3. Improvement of feature-scale profile evolution in a silicon dioxide plasma etching simulator using the level set method

    NASA Astrophysics Data System (ADS)

    Montoliu, C.; Baer, E.; Cerdá, J.; Colom, R. J.

    2015-06-01

    We present a three-dimensional simulator of silicon dioxide etching in a fluorocarbon plasma process. Explicit parametrization of the surface is currently one of the most frequently used methods to evolve the etched surface according to the equipment simulation results. These techniques update the coordinates of the vertices and need to add and/or remove faces to keep an accurate surface representation. These processes can introduce errors and produce unrealistic results, especially in complex structures. In this paper we prove the effectiveness of our level set (LS) implementation to evolve the etched surface according to etching models, resulting in a fully operational plasma etching simulator. The LS implementation is based on a surface reconstruction algorithm from scattered points enabling the simulation of complex topological changes such as coalescing or splitting of contiguous regions. Additionally, our algorithm is based on the sparse field method for reducing computational time of the surface evolution process and it is perfectly suited to be used with the Anetch software package. Finally, several structures are simulated and an experimental result is used to compare and validate the effectiveness of the simulator we have developed.

  4. Facile access to cytocompatible multicompartment micelles with adjustable Janus-cores from A-block-B-graft-C terpolymers prepared by combination of ROP and ATRP.

    PubMed

    Wang, Weiwei; Zhang, Ju; Li, Chen; Huang, Pingsheng; Gao, Shan; Han, Shangcong; Dong, Anjie; Kong, Deling

    2014-03-01

    The architecture of hydrophobic segments can determine the specific morphology of multicompartment micelles (MCMs) that are generated from aqueous assembly of amphiphilic terpolymers. In this study, we aimed to design and generate poly(?-caprolactone)-based multicompartment micelles with adjustable Janus-cores. Well-defined terpolymers with a novel A-block-B-graft-C architecture composed of biologically compatible polymers, methoxy poly(ethylene glycol) (PEG), poly(?-caprolactone) (PCL) and poly(2-(perfluorobutyl)ethyl methacrylate) (PPFEMA), were prepared by the stepwise use of ring-opening polymerization and atom transfer radical polymerization. Characterization of the obtained terpolymers was carried out by (1)H NMR and gel permeation chromatography. Results from differential scanning calorimetry and X-ray diffraction studies indicated that within the terpolymer structure, the PCL segments are in the crystalline state, while fluorocarbon segments belong to the amorphous domains. Due to the thermodynamic incompatibility of PCL and PPFEMA, MCMs could be obtained upon aqueous self-assembly of the terpolymer. The well-segregated Janus-cores with adjustable compartment balance were revealed by transmission electron microscopy. In vitro cell viability assays further demonstrated an excellent cytocompatibility of the MCMs both in mouse embryonic fibroblasts (3T3) and human acute monocytic leukemia (THP-1) cells. PMID:24389334

  5. High resolution electron energy loss spectroscopy study of Fomblin Z-tetraol thin films

    NASA Astrophysics Data System (ADS)

    Sung, Dougyong; Gellman, Andrew J.; Gui, Jing; Ma, Xiaoding

    2005-03-01

    High resolution electron energy loss spectroscopy has been used to obtain vibrational spectra of Fomblin Z-tetraol lubricant films on a commercial magnetic hard disk. The energy loss intensities of the ?(CF2) stretching mode are roughly independent of scattering angle up to angles of ??<14° indicating that they are excited by impact scattering. As a consequence there is little information that can be gleaned from the spectra about molecular orientation on the surface. A negative ion resonance enhances the energy loss cross section of the ?(CF2) stretching mode at the impact energy of EI=4 eV. It is possible that this resonance is associated with the known sensitivity of fluorocarbons to electron induced dissociation. Annealing the disk sample to T=700 K causes a dramatic decrease in the intensity of C-F stretching modes and an increase of the loss features due to C-H stretching. This indicates that the Fomblin Z-tetraol has decomposed and is exposing the a-CHx overcoat on the magnetic media surface.

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

    SciTech Connect

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

    2000-01-26

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

  7. Surface roughening of ground fused silica processed by atmospheric inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Xin, Qiang; Li, Na; Wang, Jun; Wang, Bo; Li, Guo; Ding, Fei; Jin, Huiliang

    2015-06-01

    Subsurface damage (SSD) is a defect that is inevitably induced during mechanical processes, such as grinding and polishing. This defect dramatically reduces the mechanical strength and the laser damage thresholds of optical elements. Compared with traditional mechanical machining, atmospheric pressure plasma processing (APPP) is a relatively novel technology that induces almost no SSD during the processing of silica-based optical materials. In this paper, a form of APPP, inductively coupled plasma (ICP), is used to process fused silica substrates with fluorocarbon precursor under atmospheric pressure. The surface morphology evolution of ICP-processed substrates was observed and characterized by confocal laser scanning microscope (CLSM), field emission scanning electron microscope (SEM), and atomic force microscopy (AFM). The results show that the roughness evolves with the etching depth, and the roughness evolution is a single-peaked curve. This curve results from the opening and the coalescing of surface cracks and fractures. The coalescence procedure of these microstructures was simulated with two common etched pits on a polished fused silica surface. Understanding the roughness evolution of plasma-processed surface might be helpful in optimizing the optical fabrication chain that contains APPP.

  8. Investigation of test methods, material properties, and processes for solar-cell encapsulants. Annual report

    SciTech Connect

    Willis, P. B.; Baum, B.

    1982-07-01

    Potentially useful low cost encapsulation materials are evaluated. The goal of the program is to identify, evaluate, test, and recommend encapsulant materials and processes for the production of cost-effective, long life solar cell modules. Technical investigations have concerned the development of advanced cure chemistries for lamination type pottants, the continued evaluation of soil resistant surface treatments, and the results of an accelerated aging test program for the comparison of material stabilities. Experiments are underway to assess the durability and cost effectiveness of coatings for protection of steel. Investigations are continuing with commercial maintenance coatings based on fluorocarbon and silicone-alkyd chemistries. Experiments were conducted to determine the effectiveness of occlusive coatings for wood products such as hard-board. An experimental program continued to determine the usefulness of soil resistant coatings. Primers were evaluated for effectiveness in bonding candidate pottants to outer covers, glass and substate materials. A program of accelerated aging and life predictive strategies is being conducted and data are reported for sunlamp exposure and thermal aging. Supporting activities are also discussed briefly. (LEW)

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

    NASA Astrophysics Data System (ADS)

    Bloch, Gregor; Kuczaty, Julian; Sattelmayer, Thomas

    2014-02-01

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

  10. An injectable, thermosensitive and multicompartment hydrogel for simultaneous encapsulation and independent release of a drug cocktail as an effective combination therapy platform.

    PubMed

    Wang, Weiwei; Song, Huijuan; Zhang, Ju; Li, Pan; Li, Chen; Wang, Chun; Kong, Deling; Zhao, Qiang

    2015-04-10

    Combination chemotherapy is potent to combat diseases. Simultaneous and segregated delivery of multiple drugs in a single vehicle is essential to achieve this objective. In the present study, an injectable, thermosensitive and multicompartment hydrogel (MCH) was developed by the facile cooperative and incompatible assembly of PEGylated hydrocarbon nanoparticles with PEGylated fluorocarbon nanoparticles. The cooperative assembly behavior was investigated by fluorescence resonance energy transfer (FRET) technology, and the result demonstrated that the incompatible nanoparticle cores possibly accounted for the multicompartment formation in hydrogel. Paclitaxel and doxorubicin could be easily and separately integrated into the different compartments of MCH serving as a sustained drug cocktail formulation. In vitro drug release indicated drugs were liberated in a simultaneous but independent manner without any effect on each other. In vitro and in vivo antitumor activity indicated that peritumoral injection of drug cocktail encapsulated MCH formulation could well achieve the combination effect, which significantly improved the tumor growth inhibition efficiency as well as minimized the drug-associated side effects compared to intravenous injection of free drug cocktail. Furthermore, such a delivery device would allow precise adjustment of drug dosage to the desired effect, achieve spatial-temporal simultaneous and synchronized presence of combination drugs in the target tissue and obviate repeated drug administrations to improve patient compliance. The thermosensitive multicompartment hydrogel cocktail formulation holds great promise for simultaneous and segregated delivery of multiple bioactive agents for sustained combination therapy. PMID:25683618

  11. X-Ray structural and gas phase studies of silver(i) perfluorinated carboxylate complexes with 2,2'-bipyridyl as potential precursors for chemical vapour deposition (CVD).

    PubMed

    Sz?yk, Edward; Szczesny, Robert; Wojtczak, Andrzej

    2010-02-21

    [Ag(CF(3)COO)(bpy)] (), [Ag(2)(C(2)F(5)COO)(2)(bpy)] () and [Ag(2)(C(3)F(7)COO)(2)(bpy)] () were prepared and characterized by MS-EI, (1)H, (13)C NMR, variable-temperature IR (VT-IR) spectroscopy (solid sample and evolved volatile species) and thermal analysis. Single-crystal X-ray diffraction data revealed the polymeric structure for [Ag(2)(C(2)F(5)COO)(2)(bpy)] and [Ag(6)(C(3)F(7)COO)(6)(bpy)(4)], with bridging bpy ligand, whereas for [Ag(CF(3)COO)(bpy)] the dimeric system with monodentately linked carboxylate was noted. Mass spectra analysis of () over 30-300 degrees C indicates the presence of binuclear ions [(RCOO)Ag(2)](+) as a main volatile particles, which can be transported in CVD process. VT-IR studies of gases evolved during the thermal decomposition process, demonstrate the presence of fluorocarbon species and CO(2) as the most abundant molecules. Thermal analysis of () revealed a multi-stage decomposition mechanism resulting in Ag(0) formation below 290 degrees C. Compounds were tested for silver metal spray pyrolysis and obtained layers were characterized by scanning electron microscopy (SEM-EDX) and XRD. PMID:20449428

  12. Degradation of the materials of construction in Li-ion batteries

    SciTech Connect

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

    1997-03-01

    The primary current-collector materials being used in lithium-ion cells are susceptible to environmental degradation: aluminum to pitting corrosion and copper to environmentally assisted cracking. Pitting occurs at the highly oxidizing potentials associated with the positive-electrode charge condition. However, the pitting mechanism is more complex than that typically observed in aqueous systems in that the pits are filled with a mixed metal/oxide product and exist as mounds or nodules on the surface. Electrochemical impedance spectroscopy was shown to be an effective analytical tool for quantifying and verifying aluminum corrosion behavior. Two fluorocarbon-based coatings were shown to improve the resistance of Al to pitting attack. Detailed x-ray photoelectron spectroscopy (XPS) surface analyses showed that there was very little difference in the films observed after simple immersion in either PC:DEC or EC:DMC electrolytes versus those following electrical cycling. Li and P are the predominant surface species. Finally, environmental cracking of copper can occur at or near the lithium potential and only if specific metallurgical conditions exist (work-hardening and large grain size).

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

    NASA Astrophysics Data System (ADS)

    Oka, Kazuki; Ogura, Yuta; Izumi, Yasuo

    2014-07-01

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

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

    PubMed

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

    2014-10-21

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

  15. Hemagglutination by BK virus, a tentative new member of the papovavirus group.

    PubMed

    Mäntyjärvi, R A; Arstila, P P; Meurman, O H

    1972-11-01

    Some characteristics of hemagglutination (HA) by the BK virus, a new candidate for the papovavirus group, have been studied. Hemagglutinin prepared from cell cultures was found to be partially masked by inhibitors which could be dissociated from the virus by incubation at 37 C or by fluorocarbon extraction. Optimal conditions for HA are outlined. In routine tests, 0.5% human erythrocytes were used. The reaction was carried out at pH 7.0 on ice-water slurry. BK hemagglutinin receptors on human erythrocytes were found to be more resistant to neuraminidase than polyoma receptors. By gradient centrifugation analysis, two types of particles were found to be responsible for HA: (i) full, deoxyribonucleic acid-containing particles with a density of 1.325 g/cm(3) and (ii) empty capsids with a density 1.29 g/cm(3). Based on particle counting, one HA unit was calculated to correspond to 3 x 10(6) virus particles. PMID:4629209

  16. Bench Scale Test of Absorption Slurry-ice Maker

    NASA Astrophysics Data System (ADS)

    Sasao, Hiroyuki; Yoshida, Takashi

    Slurry ice system is desirable as cold heat source for air conditioning, because it requires less conveyance power or less pipe size. On the other hand, recently absorption refrigerator is reevaluated because it can utilize various types of waste heat and it does not use fluorocarbon refrigerant. But it had been regarded to be difficult to make ice by absorption refrigerator because the refrigerant is water. However making slurry ice is possible, of cource, if the slurry ice generated by partial freezing of water is continuously taken away from the evaporator. This method was certified experimentally with a bench scale model. For ice making continuously, ice had not to be frozen stiff at water surface or inside wall of the evaporator. Then refrigerant water in the evaporator was raised swirl flow. And inside wall of the evaporator was finished by water repellent coating, and heated from outside wall. This slurry ice was adaptable to hydraulic transportation, because ice was needle crystal with about 5 mm length and ice temperature was 0°C.

  17. Atomistic Simulations of Perfluoro Phosphonic and Phosphinic Acid Membranes and Comparisons to Nafion

    SciTech Connect

    Idupulapati, Nagesh B.; Devanathan, Ramaswami; Dupuis, Michel

    2011-03-31

    We used classical molecular dynamics (MD) simulations to investigate the nanoscale morphology and proton transport properties of perfluoro phosphonic (FPA) and phosphinic acid (FPA-I) membranes as they are being considered for use in low temperature fuel cells. We systematically investigated these properties as a function of the hydration level. The changes in nanostructure, in transport dynamics of water and hydronium ions, and in water network percolation were extracted from MD simulations and compared with Nafion. Phosphonic and phosphinic acid moieties in FPA and FPA-I, have lower acidity than sulfonic acid in Nafion, yet the diffusion of water was observed to be faster in FPA and FPA-I than in Nafion, particularly at low hydration levels. However this did not give rise to notable differences in hydronium ion diffusion and water network percolation for these membranes over Nafion. Similar observations were also reported by our group recently in a study of perfluoro-sulfonyl imide membranes carrying stronger super-acids than sulfonic acid of Nafion. These findings together suggest no strong apparent correlation between the acidity strength of the functional acid groups and the dynamics of water and hydronium ions in hydrated polymer electrolyte membranes (PEMs) with similar fluorocarbon backbones and acidic group-carrying side chains. This work was supported by the US Department of Energy Basic Energy Sciences' Chemical Sciences, Geosciences & Biosciences Division. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

  18. Fluorine-rich planetary environments as possible habitats for life.

    PubMed

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

    2014-01-01

    In polar aprotic organic solvents, fluorine might be an element of choice for life that uses selected fluorinated building blocks as monomers of choice for self-assembling of its catalytic polymers. Organofluorine compounds are extremely rare in the chemistry of life as we know it. Biomolecules, when fluorinated such as peptides or proteins, exhibit a "fluorous effect", i.e., they are fluorophilic (neither hydrophilic nor lipophilic). Such polymers, capable of creating self-sorting assemblies, resist denaturation by organic solvents by exclusion of fluorocarbon side chains from the organic phase. Fluorous cores consist of a compact interior, which is shielded from the surrounding solvent. Thus, we can anticipate that fluorine-containing "teflon"-like or "non-sticking" building blocks might be monomers of choice for the synthesis of organized polymeric structures in fluorine-rich planetary environments. Although no fluorine-rich planetary environment is known, theoretical considerations might help us to define chemistries that might support life in such environments. For example, one scenario is that all molecular oxygen may be used up by oxidation reactions on a planetary surface and fluorine gas could be released from F-rich magma later in the history of a planetary body to result in a fluorine-rich planetary environment. PMID:25370378

  19. Neurologic illness associated with occupational exposure to the solvent 1-bromopropane--New Jersey and Pennsylvania, 2007-2008.

    PubMed

    2008-12-01

    1-Bromopropane (1-BP) (n-propyl bromide) is a solvent increasingly used as a substitute for ozone-depleting chloro-fluorocarbons and similar regulated compounds. 1-BP is used in vapor and immersion degreasing operations and other manufacturing processes, and as a solvent in industries using aerosol-applied adhesives. In some states, 1-BP is used as a solvent in dry cleaning because of restrictions on use of perchloroethylene (tetrachloroethylene), a possible human carcinogen. Published studies of workers exposed to 1-BP have raised concerns about occupational health risks associated with exposure. This report describes two cases involving workers exposed to 1-BP and diagnosed with clinical manifestations of neurotoxicity. The cases, when coupled with previously reported studies of workers exposed to 1-BP, illustrate potential health risks of 1-BP exposure. Clinicians and public health professionals should be alert to potential health effects among workers exposed to 1-BP, particularly in dry cleaning and other workplaces where 1-BP use might be increasing, and effective control methods to limit exposure to 1-BP should be implemented at worksites. PMID:19052528

  20. Simple fabrication of antireflective silicon subwavelength structure with self-cleaning properties.

    PubMed

    Kim, Bo-Soon; Ju, Won-Ki; Lee, Min-Woo; Lee, Cheon; Lee, Seung-Gol; Beom-Hoan, O

    2013-05-01

    A subwavelength structure (SWS) was formed via a simple chemical wet etching using a gold (Au) catalyst. Single nano-sized Au particles were fabricated by metallic self-aggregation. The deposition and thermal annealing of the thin metallic film were carried out. Thermal annealing of a thin metallic film enables the creation of metal nano particles by isolating them from each other by means of the self-aggregation of the metal. After annealing, the samples were soaked in an aqueous etching solution of hydrofluoric acid and hydrogen peroxide. When silicon (Si) was etched for 2 minutes using the Au nano particles, the reflectance was decreased almost 0% over the entire wavelength range from 300 to 1300 nm due to its deep and steeply double tapered structure. When given varying incident angle degrees from 30 degrees to 60 degrees, the reflectance was also maintained at less than 3%. Following this, the etched silicon was treated with a plasma-polymerized fluorocarbon (PPFC) film of about 5 nm using an ICP reactor for surface modification. The result of this surface treatment, the contact angle increased significantly from 27.5 degrees to 139.3 degrees. The surface modification was successful and maintained almost 0% reflectance because of the thin film deposition. PMID:23858915

  1. Hierarchical structures of AlOOH nanoflakes nested on Si nanopillars with anti-reflectance and superhydrophobicity.

    PubMed

    Yu, Eusun; Lee, Heon Ju; Ko, Tae-Jun; Kim, Seong Jin; Lee, Kwang-Ryeol; Oh, Kyu Hwan; Moon, Myoung-Woon

    2013-10-21

    A novel method to fabricate ultra-low reflective Si surfaces with nanoscale hierarchical structures is developed by the combination of AlOOH or boehmite nanoflakes nested on plasma-etched Si nanopillars. Using CF4 plasma etching, Si surfaces are nanostructured with pillar-like structures by selective etching with self-masking by fluorocarbon residues. AlOOH nanoflakes are formed by Al thin film coating with various thicknesses and subsequent immersion in boiling water, which induces the formation of nanoscale flakes through the hydrolysis reaction. AlOOH nanoflakes are formed on Si nanopillared surfaces for hierarchical structures, which are coated with a low-surface-energy material, resulting in a higher water wetting angle of over 150° and a very low contact angle hysteresis of less than 5°, and implying a self-cleaning surface. Reflectance reduced to 5.18% on average on hierarchical nanostructures in comparison to 9.63% on the Si nanopillar surfaces only. We found that Si nanopillars reduced reflection for wavelengths ranging from 200 to 1200 nm while AlOOH nanoflakes reduced reflection for wavelengths longer than 600 nm. PMID:24057013

  2. Slippery liquid-infused porous surfaces showing marine antibiofouling properties.

    PubMed

    Xiao, Linlin; Li, Junsheng; Mieszkin, Sophie; Di Fino, Alessio; Clare, Anthony S; Callow, Maureen E; Callow, James A; Grunze, Michael; Rosenhahn, Axel; Levkin, Pavel A

    2013-10-23

    Marine biofouling is a longstanding problem because of the constant challenges placed by various fouling species and increasingly restricted environmental regulations for antifouling coatings. Novel nonbiocidal strategies to control biofouling will necessitate a multifunctional approach to coating design. Here we show that slippery liquid-infused porous surfaces (SLIPSs) provide another possible strategy to obtaining promising antifouling coatings. Microporous butyl methacrylate-ethylene dimethacrylate (BMA-EDMA) surfaces are prepared via UV-initiated free-radical polymerization. Subsequent infusion of fluorocarbon lubricants (Krytox103, Krytox100, and Fluorinert FC-70) into the porous microtexture results in liquid-repellent slippery surfaces. To study the interaction with marine fouling organisms, settlement of zoospores of the alga Ulva linza and cypris larvae of the barnacle Balanus amphitrite is tested in laboratory assays. BMA-EDMA surfaces infused with Krytox103 and Krytox100 exhibit remarkable inhibition of settlement (attachment) of both spores and cyprids to a level comparable to that of a poly(ethylene glycol) (PEG)-terminated self-assembled monolayer. In addition, the adhesion strength of sporelings (young plants) of U. linza is reduced for BMA-EDMA surfaces infused with Krytox103 and Krytox100 compared to pristine (noninfused) BMA-EDMA and BMA-EDMA infused with Fluorinert FC-70. Immersion tests suggest a correlation between the stability of slippery coatings in artificial seawater and fouling resistance efficacy. The results indicate great potential for the application of this concept in fouling-resistant marine coatings. PMID:24067279

  3. A biomimetic peptide fluorosurfactant polymer for endothelialization of ePTFE with limited platelet adhesion

    PubMed Central

    Larsen, Coby C.; Kligman, Faina; Tang, Chad; Kottke-Marchant, Kandice; Marchant, Roger E.

    2007-01-01

    Endothelialization of expanded polytetrafluoroethylene (ePTFE) has the potential to improve long-term patency for small-diameter vascular grafts. Successful endothelialization requires ePTFE surface modification to permit cell attachment to this otherwise non-adhesive substrate. We report here on a peptide fluorosurfactant polymer (FSP) biomimetic construct that promotes endothelial cell (EC)-selective attachment, growth, shear stability, and function on ePTFE. The peptide FSP consists of a flexible poly(vinyl amine) backbone with EC-selective peptide ligands for specific cell adhesion and pendant fluorocarbon branches for stable anchorage to underlying ePTFE. The EC-selective peptide (primary sequence- Cys-Arg-Arg-Glu-Thr-Ala-Trp-Ala-Cys, CRRETAWAC) has demonstrated high binding affinity for the ?5?1 integrin found on ECs. Here, we demonstrate low affinity of CRRETAWAC for platelets and platelet integrins, thus providing it with EC-selectivity. This EC-selectivity could potentially facilitate rapid in vivo endothelialization and healing without thrombosis for small-diameter ePTFE vascular grafts. PMID:17507089

  4. New concepts for refrigerant leak detection and mixture measurement

    SciTech Connect

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

    1993-12-31

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

  5. Optical manipulation of nanocontainers for biotechnology

    NASA Astrophysics Data System (ADS)

    Helmerson, Kristian; Reiner, Joseph E.; Edgu-Fry, Erge; Wells, Jeffrey; Kishore, Rani; Locascio, Laurie; Gilson, Michael

    2004-10-01

    We are developing optically based techniques for the manipulation of nano-containers (containers with sub-picoliter volumes) for handling chemicals in order to perform ultra-small volume chemistry. We are currently investigating three systems, liposomes, polymersomes and hydrosomes, for use as nano-containers. Liposomes and polymersomes are closed structures composed of a lipid and polymer membrane, respectively, that acts as a barrier to separate an aqueous interior environment from an aqueous exterior environment. We are typically working with liposomes or polymersomes that are approximately 10 ?m in diameter. Hydrosomes are micron-sized, surfactant-stabilized water droplets that reside in a fluorocarbon environment. The optical techniques we are using include optical tweezers, for trapping and remotely moving the nano-containers, and an "optical scalpel" for localized disruption of lipid and polymer membranes in order to induce fusion of liposomes and polymersomes. In all three systems, we are able to bring together two similar nano-container using optical trapping and subsequently fuse them together, which allows their contents to mix. With the liposomes and hydrosomes we have been able to demonstrate their use for performing a controlled, elementary chemical reaction.

  6. The evolution of spatial ordering of oil drops fast spreading on a water surface.

    PubMed

    Yamamoto, Daigo; Nakajima, Chika; Shioi, Akihisa; Krafft, Marie Pierre; Yoshikawa, Kenichi

    2015-01-01

    The design of dynamically self-assembled systems is of high interest in science and technology. Here, we report a unique cascade in the self-ordering of droplets accompanied by a dewetting transition. The dynamic self-emergent droplets are observed when a thin liquid layer of an immiscible fluorocarbon oil (perfluorooctyl bromide, PFOB) is placed on a water surface. Due to the gradual evaporation of PFOB, a circular PFOB-free domain appears as a result of a local dewetting transition. A circular pearling structure is generated at the rim with the growth of the dewetting hole. As the next stage, linear arrays of droplets are generated in a radial manner from the centre of the hole. These one-dimensional arrangements then evolve into two-dimensional hexagonal arrays of microdroplets through collective rhythmical shrinking/expanding motions. The emergence of such dynamic patterns is discussed in terms of the nonlinear kinetics of the dewetting transition under thermodynamically dissipative conditions. PMID:25998157

  7. Temperature and humidity control system in a lunar base.

    PubMed

    Izutani, N; Kobayashi, N; Ogura, T; Nomura, I; Kawazoe, M; Yamamoto, H

    1992-01-01

    An increasing number of lunar base construction programs are in the process of developing lunar resources such as helium 3. The objective of the present work is to evaluate the temperature and humidity control system, which will allow man to live and work on the moon while developing lunar resources. The results of thermal load calculation show that the load of electric lighting is a 80 to 90% of the cooling load in the habitat module and that only the cooling function is required for temperature control. Due to this, a fluorocarbon refrigerant heat pump system was selected to satisfy reliability, energy consumption, size and weight requirements for the lunar base equipment. According to the load calculation, occupants will feel discomfort due to radiant heat from lighting fixtures. To resolve this problem, an air conditioning system, used in combination with forced convective cooling and panel cooling on the ceiling, was adopted in the living space. Moreover, the experiment on the ground was carried out to evaluate the effects of panel cooling. PMID:11537076

  8. Structural basis for the enhanced stability of highly fluorinated proteins

    PubMed Central

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

    2012-01-01

    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

  9. Fluorine: A new element in protein design

    PubMed Central

    Buer, Benjamin C; Marsh, E Neil G

    2012-01-01

    Fluorocarbons are quintessentially man-made molecules, fluorine being all but absent from biology. Perfluorinated molecules exhibit novel physicochemical properties that include extreme chemical inertness, thermal stability, and an unusual propensity for phase segregation. The question we and others have sought to answer is to what extent can these properties be engineered into proteins? Here, we review recent studies in which proteins have been designed that incorporate highly fluorinated analogs of hydrophobic amino acids with the aim of creating proteins with novel chemical and biological properties. Fluorination seems to be a general and effective strategy to enhance the stability of proteins, both soluble and membrane bound, against chemical and thermal denaturation, although retaining structure and biological activity. Most studies have focused on small proteins that can be produced by peptide synthesis as synthesis of large proteins containing specifically fluorinated residues remains challenging. However, the development of various biosynthetic methods for introducing noncanonical amino acids into proteins promises to expand the utility of fluorinated amino acids in protein design. PMID:22274989

  10. Facile catalyst separation without water: Fluorous biphase hydroformylation of olefins

    SciTech Connect

    Horvath, I.T.; Rabai, J. [Exxon Research and Engineering Co., Annandale, NJ (United States)

    1994-10-07

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

  11. Durability of polymeric materials used in zinc/bromine flow batteries

    NASA Astrophysics Data System (ADS)

    Arnold, C., Jr.

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

  12. Two episodes of acute illness in a machine shop

    SciTech Connect

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

    1989-08-01

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

  13. Implementation of ultrasonic sensing for high resolution measurement of binary gas mixture fractions.

    PubMed

    Bates, Richard; Battistin, Michele; 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

    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

  14. Heat exchanger saves $400,000 in waste heat recovery

    SciTech Connect

    Confer, L.; Kramer, K.L.

    1987-08-01

    A condensing type heat exchanger operating at Henkel Corporation's plant in Kankakee, IL, has enabled the plant to save $400,000 in energy costs within the first 22 months of operation, recouping the initial capital investment for the unit within that time frame. The heat exchanger enables the plant to accomplish what historically was considered taboo - to cool boiler stack gas down to 130/sup 0/F, below the dew point, and thus recover both sensible and latent heat from the gas. Traditionally, moisture could not be squeezed out of stack gas below the recommended temperature of 250/sup 0/F because the stack gas close to the heat exchanger tubes would approach the dew point, condense and attack metal surfaces. The condensing type heat exchanger can withstand corrosive conditions, however, because all wetted surfaces on the flue side of the shell and copper-nickel tube design are protected with an extruded Teflon fluorocarbon resin covering (not coating). The waste heat recovery system was installed over a two-month period in 1985. Performance has been above expectations with greater energy savings than originally projected. The amount of operator attention required is minimal.

  15. Comparison of CF4, CHF3 and CH2F2 plasmas used for wafer processing

    NASA Astrophysics Data System (ADS)

    Tinck, Stefan; Milenin, Alexey; Bogaerts, Annemie

    2012-10-01

    Fluorocarbon-based plasmas are widely used in the microelectronics industry for the fabrication of computer chips, i.e. in plasma etching of silicon. One such process is the etching of nanoscale trenches in the Si substrate with CHxFy plasmas as applied in shallow trench isolation (STI). By carefully altering the ratio between gases such as CF4, CHF3 and CH2F2, the overall etching process can be controlled in terms of chemical etching, sputtering and sidewall passivation. Therefore, we wish to obtain a more fundamental understanding of these plasmas and their surface processes. The plasma behavior will be simulated by a hybrid model for addressing the various plasma species, while the surface interactions of the plasma will be described by additional Monte Carlo simulations, allowing a detailed insight in the nanoscale trench etching process. Bulk plasma properties such as species densities, temperatures and fluxes towards the walls will be discussed under typical wafer processing conditions as well as surface properties including etch rate and chemical composition of the surface during trench etching. The etch rate and microscopic etch profiles will be compared with experimental data.

  16. Inorganic Bi/In thermal resist as a high-etch-ratio patterning layer for CF4/CHF3/O2 plasma etch

    NASA Astrophysics Data System (ADS)

    Tu, Yuqiang; Chapman, Glenn H.; Peng, Jun

    2004-05-01

    Bimetallic thin films containing indium and with low eutectic points, such as Bi/In, have been found to form highly sensitive thermal resists. They can be exposed by lasers with a wide range of wavelengths and be developed by diluted RCA2 solutions. The exposed bimetallic resist Bi/In can work as an etch masking layer for alkaline-based (KOH, TMAH and EDP) "wet" Si anisotropic etching. Current research shows that it can also act as a patterning and masking layer for Si and SiO2 plasma "dry" etch using CF4/CHF3. The profile of etched structures can be tuned by adding CHF3 and other gases such as Ar, and by changing the CF4/CHF3 ratio. Depending on the fluorocarbon plasma etching recipe the etch rate of laser exposed Bi/In can be as low as 0.1nm/min, 500 times lower than organic photoresists. O2 plasma ashing has little etching effect on exposed Bi/In, indicating that laser exposure is an oxidation process. Experiment result shows that single metal Indium film and bilayer Sn/In exhibit thermal resist characteristics but at higher exposure levels. They can be developed in diluted RCA2 solution and used as etch mask layers for Si anisotropic etch and plasma etch.

  17. Characteristics of secondary etching of SiO2 by ions reflected from a primary SiO2 target in a CHF3 plasma

    NASA Astrophysics Data System (ADS)

    Lee, Gyeo-Re; Hwang, Sung-Wook; Min, Jae-Ho; Moon, Sang Heup

    2003-03-01

    The etching of a secondary SiO2 target, target (2), by ions reflected from a primary SiO2 target, target (1), in a CHF3 plasma using various angles for the ions incident on target (1), ?i, was examined. The etch rate of target (2) was enhanced by collision with reflected ions and the extent of etch-rate enhancement was significantly affected by the surface roughness of target (1). The extent and range of secondary etching increased when ?i was increased from 60° to 80°. Under the conditions used in this study, the maximum scattering angle for initiating secondary etching was nearly constant, at about 60°, irrespective of ?i, when the latter was between 60° and 80°. When ?i was increased to 85°, the surface of target (1) was covered with a fluorocarbon polymer layer, which drastically decreased the extent of secondary etching. At ?i=85°, the maximum scattering angle was lowered to about 40° and, as a result, the range of secondary etching was reduced.

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  19. Langmuir Probe Measurements in an Inductively Coupled Ar/CF4 Plasmas

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  20. Mass spectra of neutral particles released during electrical breakdown of thin polymer films

    NASA Technical Reports Server (NTRS)

    Kendall, B. R. F.

    1985-01-01

    A special type of time-of-flight mass spectrometer triggered from the breakdown event was developed to study the composition of the neutral particle flux released during the electrical breakdown of polymer films problem. Charge is fed onto a metal-backed polymer surface by a movable smooth platinum contact. A slowly increasing potential from a high-impedance source is applied to the contact until breakdown occurs. The breakdown characteristics is made similar to those produced by an electron beam charging system operating at similar potentials. The apparatus showed that intense instantaneous fluxes of neutral particles are released from the sites of breakdown events. For Teflon FEP films of 50 and 75 microns thickness the material released consists almost entirely of fluorocarbon fragments, some of them having masses greater than 350 atomic mass units amu, while the material released from a 50 micron Kapton film consists mainly of light hydrocarbons with masses at or below 44 amu, with additional carbon monoxide and carbon dioxide. The apparatus is modified to allow electron beam charging of the samples.

  1. Easy route to superhydrophobic copper-based wire-guided droplet microfluidic systems.

    PubMed

    Mumm, Florian; van Helvoort, Antonius T J; Sikorski, Pawel

    2009-09-22

    Droplet-based microfluidic systems are an expansion of the lab on a chip concept toward flexible, reconfigurable setups based on the modification and analysis of individual droplets. Superhydrophobic surfaces are one suitable candidate for the realization of droplet-based microfluidic systems as the high mobility of aqueous liquids on such surfaces offers possibilities to use novel or more efficient approaches to droplet movement. Here, copper-based superhydrophobic surfaces were produced either by the etching of polycrystalline copper samples along the grain boundaries using etchants common in the microelectronics industry, by electrodeposition of copper films with subsequent nanowire decoration based on thermal oxidization, or by a combination of both. The surfaces could be easily hydrophobized with thiol-modified fluorocarbons, after which the produced surfaces showed a water contact angle as high as 171 degrees +/- 2 degrees . As copper was chosen as the base material, established patterning techniques adopted from printed circuit board fabrication could be used to fabricate macrostructures on the surfaces with the intention to confine the droplets and, thus, to reduce the system's sensitivity to tilting and vibrations. A simple droplet-based microfluidic chip with inlets, outlets, sample storage, and mixing areas was produced. Wire guidance, a relatively new actuation method applicable to aqueous liquids on superhydrophobic surfaces, was applied to move the droplets. PMID:19681579

  2. Liquid ventilation in dogs: an apparatus for normobaric and hyperbaric studies.

    PubMed

    Harris, D J; Coggin, R R; Roby, J; Feezor, M; Turner, G; Bennett, P B

    1983-04-01

    A liquid-breathing apparatus is described for remote surface studies and for use in experiments of near-hydraulic compression in dogs. It consists of a flexible tank sealed against chamber gas, containing a supply of clean warmed (38 degrees C) fluorocarbon (FC-80) equilibrated with 1 bar O2 and an electronically controlled means of delivering the liquid to the dog. Each breath (tidal volume 290 ml) was "weighed" into the animal by the signal from a force platform supporting the dog and a digital control unit that automatically actuated inspired-and expired-line solenoid valves. The apparatus was successfully used to remotely maintain liquid ventilation in awake dogs for 2 h during surface studies (5 dogs) and in dives to 1,000 m seawater (5 dogs). During liquid breathing, mean arterial O2 partial pressure was always adequate (congruent to 300 Torr) and mean arterial CO2 partial pressure was normal (less than or equal to 40 Torr). An uncompensated metabolic acidosis was indicated by low pH values and a decrease in arterial base excess to--4.5 meq x 1(-1). O2 uptake and CO2 output appeared to be significantly lower (42 and 35%, respectively) during liquid ventilation. PMID:6222021

  3. Uniform superhydrophobic surfaces using micro/nano complex structures formed spontaneously by a simple and cost-effective nonlithographic process based on anodic aluminum oxide technology

    NASA Astrophysics Data System (ADS)

    Kim, Dae-Ho; Kim, Yongsung; Kim, Byung Min; Ko, Jong Soo; Cho, Chae-Ryong; Kim, Jong-Man

    2011-04-01

    This paper presents a uniform micro/nano double-roughened superhydrophobic surface with a high static contact angle (CA) and low contact angle hysteresis (CAH). The proposed micro/nano complex structured surfaces were self-fabricated simply and efficiently using a very simple and low-cost nonlithographic sequential process, which consists of aluminum (Al) sputtering, anodization of the Al layer and pore widening, without specific equipment and additional subsequent processes. The wetting properties of the fabricated surfaces were characterized by measuring the static CAs and the CAHs after plasma polymerized fluorocarbon coating with a low surface energy. The measured static CA and CAH were 154 ± 2.3° and 5.7 ± 0.8°, respectively, showing that the fabricated double-roughened surfaces exhibit superhydrophobic behaviors clearly. In addition, the proposed double-scaled surfaces at a wafer-level exhibited uniform superhydrophobic behaviors across the wafer with an apparent CA and CAH of 153.9 ± 0.8° and 4.9 ± 1.3°, respectively.

  4. New concepts for refrigerant leak detection and mixture measurement

    NASA Astrophysics Data System (ADS)

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

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

  5. Bioinspired synthesis of a soft-nanofilament-based coating consisting of polysilsesquioxanes/polyamine and its divergent surface control.

    PubMed

    Yuan, Jian-Jun; Kimitsuka, Nobuo; Jin, Ren-Hua

    2013-04-24

    The synthesis of polysilsesquioxanes coating with controllable one-dimensional nanostructure on substrates remains a major long-term challenge by conventional solution-phase method. The hydrolytic polycondensation of organosilanes in solution normally produces a mixture of incomplete cages, ladderlike, and network structures, resulting in the poor control of the formation of specific nanostructure. This paper describes a simple aqueous process to synthesize nanofilament-based coatings of polysilsesquioxanes possessing various organo-functional groups (for example, thiol, methyl, phenyl, vinyl, and epoxy). We utilized a self-assembled nanostructured polyamine layer as a biomimetically catalytic scaffold/template to direct the formation of one-dimensional nanofilament of polysilsesquioxanes by temporally and spatially controlled hydrolytic polycondensation of organosilane. The surface nanostructure and morphology of polysilsesquioxane coating could be modulated by changing hydrolysis and condensation reaction conditions, and the orientation of nanofilaments of polysilsesquioxanes on substrates could be controlled by simply adjusting the self-assembly conditions of polyamine layer. The nanostructure and polyamine@polysilsesquioxane hybrid composition of nanofilament-based coatings were examined by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The template role of nanostructured polyamine layer for the formation of polysilsesquioxane nanofilament was confirmed by combining thin film X-ray diffraction (XRD) and XPS measurements. Moreover, these nanotextured coatings with various organo-functional groups could be changed into superhydrophobic surfaces after surface modification with fluorocarbon molecule. PMID:23534941

  6. Influence of open area ratio on microstructure shape in Cu-Ni alloy electrodeposition

    NASA Astrophysics Data System (ADS)

    Lee, Jae Min; Lee, Sung Ho; Ko, Jong Soo

    2014-09-01

    This research experimentally analyzed the influence of the open area ratio (OAR) on the formation and growth of the microstructure in Cu-Ni alloy electrodeposition. The OAR was controlled by changing the pitch of circular patterns with a diameter of 20 µm. For an OAR higher than 20 %, the electrodeposited structures grew vertically in pillar-like formations. As the OAR was decreased from 100 to 20 %, the density, height, and width of the structures increased. In addition, in this OAR range, the structures formed along the edge area of the circular patterns. In contrast, for an OAR lower than 10 %, dendrite structures were generated. The electrodeposited structures were coated with a hydrophobic plasma-polymerized fluorocarbon (PPFC) layer. In the electrodeposited sample without circular patterns (OAR = 100 %) with an OAR smaller than 1.25 %, the measured contact angles were almost the same as the contact angle (107°) measured from the flat surface without electrodeposition. In contrast, the samples with an OAR range of 2.5-50 % were modified to be superhydrophobic, and they demonstrated an excellent self-cleaning ability.

  7. Influence of open area ratio on microstructure shape in Cu-Ni alloy electrodeposition

    NASA Astrophysics Data System (ADS)

    Lee, Jae Min; Lee, Sung Ho; Ko, Jong Soo

    2015-02-01

    This research experimentally analyzed the influence of the open area ratio (OAR) on the formation and growth of the microstructure in Cu-Ni alloy electrodeposition. The OAR was controlled by changing the pitch of circular patterns with a diameter of 20 µm. For an OAR higher than 20 %, the electrodeposited structures grew vertically in pillar-like formations. As the OAR was decreased from 100 to 20 %, the density, height, and width of the structures increased. In addition, in this OAR range, the structures formed along the edge area of the circular patterns. In contrast, for an OAR lower than 10 %, dendrite structures were generated. The electrodeposited structures were coated with a hydrophobic plasma-polymerized fluorocarbon (PPFC) layer. In the electrodeposited sample without circular patterns (OAR = 100 %) with an OAR smaller than 1.25 %, the measured contact angles were almost the same as the contact angle (107°) measured from the flat surface without electrodeposition. In contrast, the samples with an OAR range of 2.5-50 % were modified to be superhydrophobic, and they demonstrated an excellent self-cleaning ability.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    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.

  9. Discrete elements for 3D microfluidics

    PubMed Central

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

    2014-01-01

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

  10. Gaseous saturable absorbers for the Helios CO2 laser systems

    NASA Astrophysics Data System (ADS)

    Haglund, R. F., Jr.; Nowak, A. V.; Czuchlewski, S. J.

    1981-09-01

    Saturable absorbers are widely used to suppress parasitic oscillations in large-aperture, high-power CO2 fusion-laser systems. This paper reports experimental results on SF6-based gaseous saturable absorbers used for parasitic suppression in the eight-beam, 10 kJ Helios fusion-laser system. The gas mix effectively quenches self-lasing in the 9 and 10 microns branches of the CO2 laser spectrum while simultaneously allowing high transmission subnanosecond multiwavelength pulses for target-irradiation experiments. The gas isolator now in use consists of SF6 and the additional fluorocarbons: 1,1-difluoroethane (FC-152a); dichlorodifluoromethane (FC-12); chloropentafluoroethane (FC-115); 1,1-dichloro 2,2-difluoroethylene (FC-1112a); chlorotrifluoroethylene (FC-1113); and perfluorocyclobutane (FC-C318). The saturation of the mix was studied as a function of incident fluence, pressure, cell length, and incident wavelength. Experimental results are presented on the saturation properties of pure SF6 and FC-152a and compared with the saturation behavior of CO2 at 400 C.

  11. Equations-of-State and Shock Response of Fluorinated Polymers: Influence of Polymer Crystallinity

    NASA Astrophysics Data System (ADS)

    Dattelbaum, Dana

    2005-07-01

    Fluoropolymers find wide application in a variety of fields due to their chemical inertness, low coefficient of friction, and ability to withstand high-temperature operating conditions. The presence of fluorine in the polymer backbone, coupled with the propensity of these polymers to adopt linear chains, often result in the presence of complex, multi-phase crystalline structures. We will examine the influence of the degree of crystallinity, and nature of crystalline phase on both static compressive and shock loaded polymer behavior in poly(tetrafluoroethylene) (PTFE), poly(chlorotrifluoroethylene), and poly(chlorotrifluoroethylene-co-vinylidene fluoride). The most widely used fluorocarbon polymer for engineering applications is poly(tetrafluoroethylene) (PTFE). PTFE exists in at least four known crystalline phases near room temperature and ambient pressure. Replacing one of the fluorines in the chemical backbone with chlorine results in a polymer with substantially different properties, poly(chlorotrifluoroethylene) or Kel-F 81. The third, related polymer that will be discussed is the high explosive binder, poly(chlorotrifluoroethylene-co-vinylidene fluoride) (Kel-F 800) that is used in PBX-9502 formulations. Accompanying static high-pressure diamond anvil cell work will also be presented and compared to dynamic results.

  12. Nephrotoxicity of halogenated vinyl cysteine compounds.

    PubMed

    Gandolfi, A J; Nagle, R B; Soltis, J J; Plescia, F H

    1981-08-01

    S-(1,2-dichlorovinyl) cysteine (DCVC), is a potent nephrotoxin. In order to determine if other vinyl cysteine conjugates were nephrotoxic, halogenated vinyl cysteines, HVC-1 and HVC-2, were prepared from chlorotrifluoroethylene (CTFE), a fluorocarbon monomer, or chlorotifluoroethylene, a metabolite of halothane, respectively. Three days after receiving DCVC (5-10 mg/kg), CD-1 mice developed focal renal tubular necrosis. Mice treated with HVC-1 or HVC-2 (5-10 mg/kg) also developed renal necrosis by 3 days post exposure. HVC-1 was not as potent as DCVC with the necrosis limited to the pars recta. At equivalent doses HVC-2 caused less necrosis of the pars recta than HVC-1. The degree of nephrotoxicity by all three compounds exhibited a dose-response from 1-25 mg/kg. Doses greater than 25 mg/kg were often lethal within 3 days and the mice had a complete zonal necrosis of the renal cortex and a two-fold increase in kidney weight. Structural analogues, S-(chlorethyl) or S-(hydroxyethyl) cysteine, did not cause renal necrosis in mice at doses up to 200 mg/kg. These studies indicate that the enzymes reportedly responsible for converting DCVC to a nephrotoxic intermediate will also bioactivate other halogenated vinyl cysteines. PMID:7302373

  13. Toxicology of the fluoroalkenes: review and research needs.

    PubMed

    Clayton, J W

    1977-12-01

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

  14. Toxicology of the fluoroalkenes: Review and research needs

    PubMed Central

    Clayton, J. Wesley

    1977-01-01

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

  15. Tris(Cyclopentadienyl)Uranium-t-Butyl: Synthesis, reactions, and mechanisms

    SciTech Connect

    Weydert, M.

    1993-04-01

    Compounds (RC{sub 5}H{sub 4}){sub 3}U(t-Bu) were prepared for R = H, Me, Et. Their decomposition products in aromatic solvents are consistent with a radical decomposition pathway induced by solvent-assisted U-C bond homolysis. NMR was used to study the reactions of (RC{sub 5}H{sub 4}){sub 3}UCl with t-BuLi (R = t-Bu, Me{sub 3}Si). Reactions of (MeC{sub 5}H{sub 4}){sub 3}U(t-Bu) with Lewis bases and fluorocarbons were studied. Analogous reaction chemistry between (RC{sub 5}H{sub 4}){sub 3}ThX systems and t-BuLi was also studied, and reactivity differences between U and Th are discussed. Synthesis of sterically crowded (RC{sub 5}H{sub 4}){sub 4}U compounds is next considered. Reaction of the trivalent (RC{sub 5}H{sub 4}){sub 3}U with (RC{sub 5}H{sub 4}){sub 2}Hg results in formation of (RC{sub 5}H{sub 4}){sub 4}U. Steric congestion, cyclopentadienyl ligand exchange, and electron transfer are discussed. (DLC)

  16. Tris(Cyclopentadienyl)Uranium-t-Butyl: Synthesis, reactions, and mechanisms

    SciTech Connect

    Weydert, M.

    1993-04-01

    Compounds (RC[sub 5]H[sub 4])[sub 3]U(t-Bu) were prepared for R = H, Me, Et. Their decomposition products in aromatic solvents are consistent with a radical decomposition pathway induced by solvent-assisted U-C bond homolysis. NMR was used to study the reactions of (RC[sub 5]H[sub 4])[sub 3]UCl with t-BuLi (R = t-Bu, Me[sub 3]Si). Reactions of (MeC[sub 5]H[sub 4])[sub 3]U(t-Bu) with Lewis bases and fluorocarbons were studied. Analogous reaction chemistry between (RC[sub 5]H[sub 4])[sub 3]ThX systems and t-BuLi was also studied, and reactivity differences between U and Th are discussed. Synthesis of sterically crowded (RC[sub 5]H[sub 4])[sub 4]U compounds is next considered. Reaction of the trivalent (RC[sub 5]H[sub 4])[sub 3]U with (RC[sub 5]H[sub 4])[sub 2]Hg results in formation of (RC[sub 5]H[sub 4])[sub 4]U. Steric congestion, cyclopentadienyl ligand exchange, and electron transfer are discussed. (DLC)

  17. Solvent vapor mediated polymer adsorption in thin films.

    PubMed

    Kiff, F Thomas; Richards, Randal W; Thompson, Richard L

    2004-05-25

    The effectiveness of a "solvent annealing" process was investigated for thin (approximately 150 nm) polystyrene films, in which the diffusion and reorganization of polymer chains were mediated by the controlled absorption of cyclohexane vapor. Results were compared with conventional "thermal annealing" of films under vacuum above the glass transition temperature. Elastic recoil detection analysis (ERDA) was used to determine the surface excesses of fluorocarbon end-capped polystyrene (hPSF) and poly(styrene-b-dimethylsiloxane) (hPS-PDMS) in deuterated polystyrene (dPS) films. Both annealing methods enabled diffusion of the surface-active polymers; however, only thermal annealing gave rise to a surface excess in hPSF/dPS films. The inhibition ofhPSF adsorption under solvent annealing was due to the low surface tension of cyclohexane. In contrast, hPS-PDMS, having a larger surface-active group than that of hPSF, was found in excess at the air surface under solvent annealing, and surface excesses were consistent with the formation of saturated monolayers in blended films. The mixing of hPS-PDMS with dPS was inhibited by the unfavorable interaction between the PDMS block of the copolymer and the homopolymer. The slow interdiffusion of hPS-PDMS in dPS is consistent with the formation of micelles, and the formation of an excess layer at the air surface may be kinetically inhibited by the rate of dissociation of hPS-PDMS micelles. PMID:15969153

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

    PubMed

    Sajjad, Faiza; Noreen, Umara; Zaman, Khalid

    2014-11-01

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

  19. Environmental fate of the next generation refrigerant 2,3,3,3-tetrafluoropropene (HFO-1234yf).

    PubMed

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

    2014-11-18

    The hydrofluoroolefin 2,3,3,3-tetrafluoropropene (HFO-1234yf) has been introduced to replace 1,1,1,2-tetrafluoroethane (HFC-134a) as refrigerant in mobile, including vehicle, air conditioning systems because of its lower global warming potential. HFO-1234yf is volatile at ambient temperatures; however, high production volumes and widespread handling are expected to release this fluorocarbon into terrestrial and aquatic environments, including groundwater. Laboratory experiments explored HFO-1234yf degradation by (i) microbial processes under oxic and anoxic conditions, (ii) abiotic processes mediated by reactive mineral phases and zerovalent iron (Fe(0), ZVI), and (iii) cobalamin-catalyzed biomimetic transformation. These investigations demonstrated that HFO-1234yf was recalcitrant to microbial (co)metabolism and no transformation was observed in incubations with ZVI, makinawite (FeS), sulfate green rust (GR(SO4)), magnetite (Fe(3)O(4)), and manganese oxide (MnO2). Sequential reductive defluorination of HFO-1234yf to 3,3,3-trifluoropropene and 3,3-dichloropropene with concomitant stoichiometric release of fluoride occurred in incubations with reduced cobalamins (e.g., vitamin B12) indicating that biomolecules can transform HFO-1234yf at circumneutral pH and at ambient temperature. Taken together, these findings suggest that HFO-1234yf recalcitrance in aquifers should be expected; however, HFO-1234yf is not inert and a biomolecule may mediate reductive transformation in low redox environments, albeit at low rates. PMID:25329364

  20. Analysis and interpretation of the performance degradation of glass Resistive Plate Chambers operated in streamer mode

    NASA Astrophysics Data System (ADS)

    Calcaterra, A.; de Sangro, R.; Patteri, P.; Piccolo, M.; Della Mea, G.; Restello, S.; Ferri, F.; Musella, P.; Redaelli, N.; Tabarelli de Fatis, T.; Tinti, G.; Mannocchi, G.; Trinchero, G.

    2007-10-01

    The long-term stability of Resistive Plate Chambers (RPCs) with glass electrodes was studied for one year with a dedicated test station hosting about 10 m2 of detectors. RPCs were operated in streamer mode with a ternary gas mixture containing argon (27%), isobutane (9%) and tetrafluoroethane (64%). Environmental conditions were kept under control and, in particular, the water pollution in the gas, deemed responsible for the degradation of glass RPC performance, was monitored never to exceed 30 ppm in the exhaust line. Evidence for a substantial aging of the detectors was observed, resulting in a loss of efficiency correlated to an increased rate of spurious streamers. This can be ascribed to the chemical attack of the glass surface by hydrofluoric acid formed in the streamer process, as confirmed by detailed morphological and chemical analyses of the electrode surface. Our results strengthen the indication that the instability of glass RPCs in the long term is related to the use of fluorocarbons as quenching medium and is not due to external pollutants.

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

    PubMed Central

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

    1975-01-01

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

  2. Etching characteristics and mechanism of SiN(x) films for nano-devices in CH2F2/O2/Ar inductively coupled plasma: effect of O2 mixing ratio.

    PubMed

    Son, Jinyoung; Efremov, Alexander; Yun, Sun Jin; Yeom, Geun Young; Kwonl, Kwang-ho

    2014-12-01

    Etching characteristics and mechanisms of low-temperature SiN(x) thin films for nano-devices in CH2F2/O2/Ar inductively-coupled plasmas were studied. The etching rates of SiN(x) thin films as well as the etching selectivities over Si and photoresist were measured in the range of 25-75% O2 in a feed gas at fixed CH2F2 content (25%), gas pressure (6 mTorr), input power (900 W), bias power (200 W), and total gas flow rate (40 sccm). Plasma parameters were analyzed using the Langmuir probe diagnostics and optical emission spectroscopy. The chemical states of the etched surfaces were examined by the X-ray photoelectron spectroscopy. It was found that the non-monotonic (with a maximum at about 50-60% O2) SiN(x) etching rate does not correlate with monotonically decreasing F atom flux and ion energy flux. It was proposed that, under the given set of experimental conditions, the SiN(x) etching process is also controlled by the O and H atom fluxes through the destruction of the fluorocarbon polymer layer. PMID:25971095

  3. In-situ alteration of minerals by acidic ground water resulting from mining activities: Preliminary evaluation of method

    USGS Publications Warehouse

    Lind, Carol J.; Creasey, C.L.; Angeroth, C.

    1999-01-01

    The chemical composition of the Cu-mining-related acidic ground water (pH ~ 3.5 to near neutral) in Pinal Creek Basin, Arizona has been monitored since 1980. In-situ experiments are planned using alluvial sediments placed in the ground-water flow path to measure changes in mineral and chemical composition and changes in dissolution rates of subsurface alluvial sediments. The test results should help refine developed models of predicted chemical changes in ground-water composition and models of streamflow. For the preliminary test, sediment from the depth of the well screen of a newly drilled well was installed in three wells, the source well (pH 4.96) and two up-gradient wells (pHs 4.27 and 4.00). The sediment was placed in woven macrofilters, fastened in series to polyvinyl chloride (PVC) pipes, and hung at the screened level of each well. After interacting with the slowly moving ground water for 48 days, the test sediments were removed for analysis. There was no evidence that any of the materials used were biologically or chemically degraded or that the porosity of the filters was diminished by ferric hydroxide precipitation. These materials included 21-??m-pore (21PEMF) and 67-??m-pore polyester and the 174-??m-pore fluorocarbon Spectra/mesh macrofilters containing the in-situ sediment, the polypropylene (PP) macrofilter support structures, and the Nylon (NY) monofilament line used to attach the samples to the PVC pipe. Based on chemical and mineral composition and on particle-size distribution of the sediment before and after ground-water exposure, the 21PEMF macrofilter was chosen as the most suitable macrofilter for the long-term in-situ experiment. Tests also showed that the PP support structures and the NY monofilament line were sufficiently durable for this experiment.The chemical composition of the Cu-mining-related acidic ground water (pH approx. 3.5 to near neutral) in Pinal Creek Basin, Arizona has been monitored since 1980. In-situ experiments are planned using alluvial sediments placed in the ground-water flow path to measure changes in mineral and chemical composition and changes in dissolution rates of subsurface alluvial sediments. The test results should help refine developed models of predicted chemical changes in ground-water composition and models of streamflow. For the preliminary test, sediment from the depth of the well screen of a newly drilled well was installed in three wells, the source well (pH 4.96) and two up-gradient wells (pHs 4.27 and 4.00). The sediment was placed in woven macrofilters, fastened in series to polyvinyl chloride (PVC) pipes, and hung at the screened level of each well. After interacting with the slowly moving ground water for 48 days, the test sediments were removed for analysis. There was no evidence that any of the materials used were biologically or chemically degraded or that the porosity of the filters was diminished by ferric hydroxide precipitation. These materials included 21-??m-pore (21PEMF) and 67-??m-pore polyester and the 174-??m-pore fluorocarbon Spectra/mesh macrofilters containing the in-situ sediment, the polypropylene (PP) macrofilter support structures, and the Nylon (NY) monofilament line used to attach the samples to the PVC pipe. Based on chemical and mineral composition and on particle-size distribution of the sediment before and after ground-water exposure, the 21PEMF macrofilter was chosen as the most suitable macrofilter for the long-term in-situ experiment. Tests also showed that the PP support structures and the NY monofilament line were sufficiently durable for this experiment.

  4. Genesis of ion-adsorption type REE ores in Thailand

    NASA Astrophysics Data System (ADS)

    Sanematsu, K.; Yoshiaki, K.; Watanabe, Y.

    2012-04-01

    Ion-adsorption type REE deposits, which have been economically mined only in southern China, are predominant supply sources for HREE in the world. The ore bodies consist of weathered granites called ion-adsorption ores. The majority of REE (>50 %) are electrostatically adsorbed onto weathering products in the ores and they can be extracted by ion exchange using an electrolyte solution (e.g., ammonium sulfate solution). Recently the occurrences of ion-adsorption ores have been reported in Indochina, SE Asia. In this study, we discuss geochemical and mineralogical characteristics of parent granites and weathered granites in Thailand in order to reveal the genesis of ion-adsorption ores. Permo-Triassic and Cretaceous-Paleogene granite plutons are distributed from northern Thailand to western Indonesia through eastern Myanmar and Peninsular Malaysia. They are mostly ilmenite-series calcalkaline biotite or hornblende-biotite granites. REE contents of the granites range from 60 to 600 ppm and they are relatively high in Peninsula Thailand. REE-bearing minerals consist mainly of apatite, zircon, allanite, titanite, monazite and xenotime. Some I-type granites contain REE fluorocarbonate (probably synchysite-(Ce)) in cavities and cracks in feldspars and it is the dominant source of REE for ion-adsorption ores because the fluorocarbonate is easily soluble during weathering. In contrast, insoluble monazite and xenotime are not preferable for ion-adsorption ores although they are common ore minerals of placer REE deposits. Weathered granites show REE contents ranging from 60 to 1100 ppm in Thailand because REE are relatively immobile compared with mobile elements (e.g., Na, K, Ca). In the weathered granites, REE are contained in residual minerals and secondary minerals and are adsorbed onto the surface of weathering products. A weathering profile of granite with ion-adsorption type mineralization can be divided into upper and lower parts based on REE enrichment and Ce anomalies reflecting a redox condition during weathering. The upper part of the profile is a leached zone characterized by positive Ce anomaly and lower REE contents compared with the parent granite. This indicates that acidic soil water in an oxidizing condition immobilized Ce4+ as CeO2 and transported REE3+ downward. In contrast, the lower part of the profile is an accumulation zone characterized by negative Ce anomaly and higher REE contents. This indicates that the transported REE3+ (depleted in Ce) were adsorbed onto weathering products and/or distributed into secondary minerals such as rhabdophane. This immobilization of REE results from the increase of pH and subsequent decrease of REE solubility due to the contact with higher pH groundwater. Percentages of adsorbed REE to whole-rock REE are also higher in the accumulation zone than in the leached zone. As the majority of REE in the weathered granites are present in the ion-adsorption phase with negative Ce anomaly, the percentages of adsorbed REE are positively correlated with the whole-rock negative Ce anomaly. Although fractionation of LREE/HREE is controlled by the occurrences of REE-bearing minerals and adsorption by weathering products, the ion-adsorption phase tends to be enriched in LREE relative to whole-rock compositions of weathered granites.

  5. Evaluation of tumor ischemia in response to an indole-based vascular disrupting agent using BLI and 19F MRI

    PubMed Central

    Zhou, Heling; Hallac, Rami R; Lopez, Ramona; Denney, Rebecca; MacDonough, Matthew T; Li, Li; Liu, Li; Graves, Edward E; Trawick, Mary Lynn; Pinney, Kevin G; Mason, Ralph P

    2015-01-01

    Vascular disrupting agents (VDAs) have been proposed as an effective broad spectrum approach to cancer therapy, by inducing ischemia leading to hypoxia and cell death. A novel VDA (OXi8007) was recently reported to show rapid acute selective shutdown of tumor vasculature based on color-Doppler ultrasound. We have now expanded investigations to noninvasively assess perfusion and hypoxiation of orthotopic human MDA-MB-231/luc breast tumor xenografts following the administration of OXi8007 based on dynamic bioluminescence imaging (BLI) and magnetic resonance imaging (MRI). BLI showed significantly lower signal four hours after the administration of OXi8007, which was very similar to the response to combretastatin A-4P (CA4P), but the effect lasted considerably longer, with the BLI signal remaining depressed at 72 hrs. Meanwhile, control tumors exhibited minimal change. Oximetry used 19F MRI of the reporter molecule hexafluorobenzene and FREDOM (Fluorocarbon Relaxometry using Echo Planar Imaging for Dynamic Oxygen Mapping) to assess pO2 distributions during air and oxygen breathing. pO2 decreased significantly upon the administration of OXi8007 during oxygen breathing (from 122 ± 64 to 34 ± 20 Torr), with further decrease upon switching the gas to air (pO2 = 17 ± 9 Torr). pO2 maps indicated intra-tumor heterogeneity in response to OXi8007, though ultimately all tumor regions became hypoxic. Both BLI and FREDOM showed the efficacy of OXi8007. The pO2 changes measured by FREDOM may be crucial for future study of combined therapy. PMID:25973335

  6. Two episodes of acute illness in a machine shop.

    PubMed Central

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

    1989-01-01

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

  7. High microvascular endothelial water permeability in mouse lung measured by a pleural surface fluorescence method.

    PubMed Central

    Carter, E P; Olveczky, B P; Matthay, M A; Verkman, A S

    1998-01-01

    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 perfused via the pulmonary artery with solutions of specified osmolalites containing a high-molecular-weight fluorescent dextran. An increase in perfusate osmolality produced a prompt decrease in surface fluorescence due to dye dilution in the capillaries, followed by a slower return to initial fluorescence as capillary and lung interstitial osmolality equilibrate. A mathematical model was developed to determine the osmotic water permeability coefficient (Pf) of lung microvessels from the time course of pleural surface fluorescence. As predicted, the magnitude of the prompt change in surface fluorescence increased with decreased pulmonary artery perfusion rate and increased osmotic gradient size. With raffinose used to induce the osmotic gradient, Pf was 0.03 cm/s at 23 degrees C and was reduced 54% by 0.5 mM HgCl2. Temperature dependence measurements gave an Arrhenius activation energy (Ea) of 5.4 kcal/mol (12-37 degrees C). The apparent Pf induced by the smaller osmolytes mannitol and glycine was 0.021 and 0.011 cm/s (23 degrees C). Immunoblot analysis showed approximately 1.4 x 10(12) aquaporin-1 water channels/cm2 of capillary surface, which accounted quantitatively for the high Pf. These results establish a novel method for measuring osmotically driven water permeability across microvessels in intact lung. The high Pf, low Ea, and mercurial inhibition indicate the involvement of molecular water channels in water transport across the lung endothelium. PMID:9545071

  8. Anesthetic gases and global warming: Potentials, prevention and future of anesthesia

    PubMed Central

    Gadani, Hina; Vyas, Arun

    2011-01-01

    Global warming refers to an average increase in the earth?s temperature, which in turn causes changes in climate. A warmer earth may lead to changes in rainfall patterns, a rise in sea level, and a wide range of impacts on plants, wildlife, and humans. Greenhouse gases make the earth warmer by trapping energy inside the atmosphere. Greenhouse gases are any gas that absorbs infrared radiation in the atmosphere and include: water vapor, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), halogenated fluorocarbons (HCFCs), ozone (O3), perfluorinated carbons (PFCs), and hydrofluorocarbons (HFCs). Hazardous chemicals enter the air we breathe as a result of dozens of activities carried out during a typical day at a healthcare facility like processing lab samples, burning fossil fuels etc. We sometimes forget that anesthetic agents are also greenhouse gases (GHGs). Anesthetic agents used today are volatile halogenated ethers and the common carrier gas nitrous oxide known to be aggressive GHGs. With less than 5% of the total delivered halogenated anesthetic being metabolized by the patient, the vast majority of the anesthetic is routinely vented to the atmosphere through the operating room scavenging system. The global warming potential (GWP) of a halogenated anesthetic is up to 2,000 times greater than CO2. Global warming potentials are used to compare the strength of different GHGs to trap heat in the atmosphere relative to that of CO2. Here we discuss about the GWP of anesthetic gases, preventive measures to decrease the global warming effects of anesthetic gases and Xenon, a newer anesthetic gas for the future of anesthesia. PMID:25885293

  9. Dynamically reconfigurable complex emulsions via tunable interfacial tensions

    PubMed Central

    Zarzar, Lauren D.; Sresht, Vishnu; Sletten, Ellen M.; Kalow, Julia A.; Blankschtein, Daniel; Swager, Timothy M.

    2015-01-01

    Emulsification is a powerful, well-known technique for mixing and dispersing immiscible components within a continuous liquid phase. Consequently, emulsions are central components of medicine, food and performance materials. Complex emulsions, including multiple emulsions and Janus droplets which contain hemispheres of differing material, are of increasing importance1 in pharmaceuticals and medical diagnostics2, in the fabrication of microparticles and capsules3–5 for food6, in chemical separations7, in cosmetics8, and in dynamic optics9. Because complex emulsion properties and functions are related to the droplet geometry and composition, the development of rapid, simple fabrication approaches allowing precise control over the droplets’ physical and chemical characteristics is critical. Significant advances in the fabrication of complex emulsions have been made using a number of procedures, ranging from large-scale, less precise techniques that give compositional heterogeneity using high-shear mixers and membranes10, to small-volume but more precise microfluidic methods11,12. However, such approaches have yet to create droplet morphologies that can be controllably altered after emulsification. Reconfigurable complex liquids potentially have greatly increased utility as dynamically tunable materials. Here we describe an approach to the one-step fabrication of three- and four-phase complex emulsions with highly controllable and reconfigurable morphologies. The fabrication makes use of the temperature-sensitive miscibility of hydrocarbon, silicone and fluorocarbon liquids, and is applied to both the microfluidic and the scalable batch production of complex droplets. We demonstrate that droplet geometries can be alternated between encapsulated and Janus configurations by varying the interfacial tensions using hydrocarbon and fluorinated surfactants including stimuli-responsive and cleavable surfactants. This yields a generalizable strategy for the fabrication of multiphase emulsions with controllably reconfigurable morphologies and the potential to create a wide range of responsive materials. PMID:25719669

  10. Chemical compatibility screening test results

    SciTech Connect

    Nigrey, P.J.; Dickens, T.G.

    1997-12-01

    A program for evaluating packaging components that may be used in transporting mixed-waste forms has been developed and the first phase has been completed. This effort involved the screening of ten plastic materials in four simulant mixed-waste types. These plastics were butadiene-acrylonitrile copolymer rubber, cross-linked polyethylene (XLPE), epichlorohydrin rubber, ethylene-propylene rubber (EPDM), fluorocarbon (Viton or Kel-F), polytetrafluoroethylene, high-density polyethylene (HDPE), isobutylene-isoprene copolymer rubber (butyl), polypropylene, and styrene-butadiene rubber (SBR). The selected simulant mixed wastes were (1) an aqueous alkaline mixture of sodium nitrate and sodium nitrite; (2) a chlorinated hydrocarbon mixture; (3) a simulant liquid scintillation fluid; and (4) a mixture of ketones. The testing protocol involved exposing the respective materials to 286,000 rads of gamma radiation followed by 14-day exposures to the waste types at 60{degrees}C. The seal materials were tested using vapor transport rate (VTR) measurements while the liner materials were tested using specific gravity as a metric. For these tests, a screening criterion of 0.9 g/hr/m{sup 2} for VTR and a specific gravity change of 10% was used. Based on this work, it was concluded that while all seal materials passed exposure to the aqueous simulant mixed waste, EPDM and SBR had the lowest VTRs. In the chlorinated hydrocarbon simulant mixed waste, only Viton passed the screening tests. In both the simulant scintillation fluid mixed waste and the ketone mixture simulant mixed waste, none of the seal materials met the screening criteria. For specific gravity testing of liner materials, the data showed that while all materials with the exception of polypropylene passed the screening criteria, Kel-F, HDPE, and XLPE offered the greatest resistance to the combination of radiation and chemicals.

  11. On-Chip Titration of an Anticoagulant Argatroban and Determination of the Clotting Time within Whole Blood or Plasma Using a Plug-Based Microfluidic System

    PubMed Central

    Song, Helen; Li, Hung-Wing; Munson, Matthew S.; Van Ha, Thuong G.; Ismagilov, Rustem F.

    2006-01-01

    This paper describes extending plug-based microfluidics to handling complex biological fluids such as blood, solving the problem of injecting additional reagents into plugs, and applying this system to measuring of clotting time in small volumes of whole blood and plasma. Plugs are droplets transported through microchannels by fluorocarbon fluids. A plug-based microfluidic system was developed to titrate an anticoagulant (argatroban) into blood samples and to measure the clotting time using the activated partial thromboplastin time (APTT) test. To carry out these experiments, the following techniques were developed for a plug-based system: (i) using Teflon AF coating on the microchannel wall to enable formation of plugs containing blood and transport of the solid fibrin clots within plugs, (ii) using a hydrophilic glass capillary to enable reliable merging of a reagent from an aqueous stream into plugs, (iii) using bright-field microscopy to detect the formation of a fibrin clot within plugs and using fluorescent microscopy to detect the production of thrombin using a fluorogenic substrate, and (iv) titration of argatroban (0–1.5 ?g/mL) into plugs and measurement of the resulting APTTs at room temperature (23 °C) and physiological temperature (37 °C). APTT measurements were conducted with normal pooled plasma (platelet-poor plasma) and with donor’s blood samples (both whole blood and platelet-rich plasma). APTT values and APTT ratios measured by the plug-based microfluidic device were compared to the results from a clinical laboratory at 37 °C. APTT obtained from the on-chip assay were about double those from the clinical laboratory but the APTT ratios from these two methods agreed well with each other. PMID:16841902

  12. Super-hydrophobicity and oleophobicity of silicone rubber modified by CF 4 radio frequency plasma

    NASA Astrophysics Data System (ADS)

    Gao, Song-Hua; Gao, Li-Hua; Zhou, Ke-Sheng

    2011-03-01

    Owing to excellent electric properties, silicone rubber (SIR) has been widely employed in outdoor insulator. For further improving its hydrophobicity and service life, the SIR samples are treated by CF 4 radio frequency (RF) capacitively coupled plasma. The hydrophobic and oleophobic properties are characterized by static contact angle method. The surface morphology of modified SIR is observed by atom force microscope (AFM). X-ray photoelectron spectroscopy (XPS) is used to test the variation of the functional groups on the SIR surface due to the treatment by CF 4 plasma. The results indicate that the static contact angle of SIR surface is improved from 100.7° to 150.2° via the CF 4 plasma modification, and the super-hydrophobic surface of modified SIR, which the corresponding static contact angle is 150.2°, appears at RF power of 200 W for a 5 min treatment time. It is found that the super-hydrophobic surface ascribes to the coaction of the increase of roughness created by the ablation action and the formation of [-SiF x(CH 3) 2- x-O-] n ( x = 1, 2) structure produced by F atoms replacement methyl groups reaction, more importantly, the formation of [-SiF 2-O-] n structure is the major factor for super-hydrophobic surface, and it is different from the previous studies, which proposed the fluorocarbon species such as C-F, C-F 2, C-F 3, CF-CF n, and C-CF n, were largely introduced to the polymer surface and responsible for the formation of low surface energy.

  13. In situ measurement of the bonded film thickness of Z-Tetraol lubricant on magnetic recording media

    SciTech Connect

    Zhu Lei; Li Feng [Material Science Laboratory, Recording Media Operation, Seagate Technology International, 16 Woodlands Loop, Singapore 738340 (Singapore)

    2010-10-15

    Currently, the bonded film thickness of perfluoropolyether lubricant on top of magnetic recording media is measured by a two-step process. First, the media disk has to be rinsed thoroughly using a fluorocarbon solvent (for instance, Vetrel) to remove the mobile lubricant. Second, the thickness of the remaining lubricant on the media surface which is regarded as the bonded lubricant thickness is then measured either by Fourier transform infrared spectroscopy (FTIR) or electron spectroscopy for chemical analysis. As the total lubricant thickness approaches single molecular dimension ({approx}10 A), current methods face tremendous challenge on the accuracy and sensitivity of the measurement. We studied the spectral characteristics responding to the lubricant bonding with the carbon overcoat by the time-of-flight secondary ion mass spectra and proposed to use the peak area ratio (C{sub 3}H{sub 2}F/C{sub 3}H{sub 5}O and C{sub 4}H{sub 10}O/C{sub 3}H{sub 6}O{sub 2}) to characterize the bonded Z-Tetraol lubricant that produces a direct bonded lubricant thickness measurement without the need to remove the mobile lubricant with a solvent. After taking the background signal of disks prior to bonding by UV irradiation into account, this method becomes independent of the total lubricant thickness as well as shows good correlation linearity (R{sup 2{approx}}87%) with the current FTIR method for the ratio of C{sub 4}H{sub 10}O/C{sub 3}H{sub 6}O{sub 2}.

  14. Development of an all-metal thick film cost effective metallization system for solar cells. Final report, May 1980-January 1983

    SciTech Connect

    Ross, B.; Parker, J.

    1983-12-01

    Properties of copper pastes did not reproduce earlier results in rheology and metallurgy. Electrodes made with pastes produced under the previous contract were analyzed and raw material characteristics were compared. A needle-like structure was observed on the earlier electroded solar cells, and was identified as eutectic copper-silicon. Experiments were conducted with variations in paste parameters, firing conditions, including gas ambients, furnace furniture, silicon surface and others to improve performance characteristics. Improved adhesion with copper pastes containing silver fluoride, as well as those containing fluorocarbon powder was obtained. Front contact experiments were done with silver fluoride activated pastes on bare silicon, silicon oxide and silicon nitride coated silicon wafers. Adhesion of pastes with AgF on silicon nitride coated wafers was good, but indications were that all cells were shunted and the conclusion was that these systems were unsuitable for front contacts. Experiments with aluminum back surfaces and screened contacts to that surface were begun. Low temperature firing tended to result in S shaped IV curves. This was attributed to a barrier formed at the silicon-copper interface. A cooperative experiment was initiated on the effect of heat-treatments in various atmospheres on the hydrogen profile of silicon surfaces. Contact theory was explored to determine the role of various parameters on tunneling and contact resistance. Data confirm that the presence of eutectic Al-Si additions are beneficial for low contact resistance and fill factors in back contacts. Copper pastes with different silver fluoride additions were utilized as front contacts at two temperatures. Data shows various degrees of shunting. Finally, an experiment was run with carbon monoxide gas used as the reducing ambient during firing.

  15. A self-assembled monolayer-based micropatterned array for controlling cell adhesion and protein adsorption.

    PubMed

    Kim, Dong Jin; Lee, Jong Min; Park, Jin-Goo; Chung, Bong Geun

    2011-05-01

    We developed a surface micropatterning technique to control the cell adhesion and protein adsorption. This micropatterned array system was fabricated by a photolithography technique and self-assembled monolayer (SAM) deposition. It was hypothesized that the wettability and functional terminal group would regulate cell adhesion and protein adsorption. To demonstrate this hypothesis, glass-based micropatterned arrays with various functional terminal groups, such as amine (NH(2)) group (3-aminopropyl-triethoxysilane, APT), methyl (CH(3)) group (trichlorovinylsilane, TVS), and fluorocarbon (CF(3)) group (trichloro(1H, 1H, 2H, 2H-perfluorooctyl)silane, FOTS), were used. The contact angle was measured to determine the hydrophilic and hydrophobic properties of materials, demonstrating that TVS and FOTS were hydrophobic, whereas APTs were relatively hydrophilic. The cell adhesion was significantly affected by the wettability, showing that the cells were not adhered to hydrophobic surfaces, such as TVS and FOTS. Thus, the cells were selectively adhered to glass substrates within TVS- and FOTS-based micropatterned arrays. However, the cells were randomly adhered to APTs-based micropatterned arrays due to hydrophilic property of APTs. Furthermore, the protein adsorption of the SAM-based micropatterned array was analyzed, showing that the protein was more absorbed to the TVS surface. The surface functional terminal group enabled the control of protein adsorption. Therefore, this SAM-based micropatterned array system enabled the control of cell adhesion and protein adsorption and could be a potentially powerful tool for regulating the cell-cell interactions in a well-defined microenvironment. PMID:21449031

  16. Polycyclic aromatic hydrocarbons (PAHs) in exhaust emissions from diesel engines powered by rapeseed oil methylester and heated non-esterified rapeseed oil

    NASA Astrophysics Data System (ADS)

    Vojtisek-Lom, Michal; Czerwinski, Jan; Lení?ek, Jan; Sekyra, Milan; Topinka, Jan

    2012-12-01

    Polycyclic aromatic hydrocarbons (PAHs) of exhaust emissions were studied in four direct-injection turbocharged four-cylinder diesel engines, with power ratings of 90-136 kW. The engines were operated on biodiesel (B-100), a blend of 30% biodiesel in diesel fuel (B-30), and heated rapeseed oil (RO) in two independent laboratories. Diesel particle filters (DPF) and selective catalytic reduction (SCR) systems were used with B-30 and B-100. Concentrations of individual PAHs sampled in different substrates (quartz, borosilicate fiber and fluorocarbon membrane filters, polyurethane foam) were analyzed using different methods. Benzo[a]pyrene toxic equivalents (BaP TEQ) were calculated using different sets of toxic equivalency factors (TEF). Operation on B-100 without aftertreatment devices, compared to diesel fuel, yielded a mean reduction in PAHs of 73%, consistent across engines and among TEF used. A lower PAH reduction was obtained using B-30. The BaP TEQ reductions on DPF were 91-99% using B-100, for one non-catalyzed DPF, and over 99% in all other cases. The BaP TEQ for heated RO were higher than those for B-100 and one half lower to over twice as high as that of diesel fuel. B-100 and RO samples featured, compared to diesel fuel, a relatively high share of higher molecular weight PAH and a relatively low share of lighter PAHs. Using different sets of TEF or different detection methods did not consistently affect the observed effect of fuels on BaP TEQ. The compilation of multiple tests was helpful for discerning emerging patterns. The collection of milligrams of particulate matter per sample was generally needed for quantification of all individual PAHs.

  17. Multiple-orifice liquid injection into hypersonic airstreams and applications to ram C-3 flight

    NASA Technical Reports Server (NTRS)

    Weaver, W. L.

    1972-01-01

    Experimental data are presented for the oblique injection of water and three electrophilic liquids (fluorocarbon compounds) through multiple-orifice nozzles from a flat plate and the sides of a hemisphere-cone (0.375 scale of RAM C spacecraft) into hypersonic airstreams. The nozzle patterns included single and multiple orifices, single rows of nozzles, and duplicates of the RAM C-III nozzles. The flat-plate tests were made at Mach 8. Total pressure was varied from 3.45 MN/m2 to 10.34 MN/m2, Reynolds number was varied form 9,840,000 per meter to 19,700,000 per meter, and liquid injection pressure was varied from 0.69 MN/m2 to 3.5 MN/m2. The hemisphere-cone tests were made at Mach 7.3. Total pressure was varied from 1.38 MN/m2, to 6.89 MN/m2, Reynolds number was varied from 3,540,000 per meter to 17,700,000 per meter, and liquid-injection pressure was varied from 0.34 MN/m2 to 4.14 MN/m2. Photographs of the tests and plots of liquid-penetration and spray cross-section area are presented. Maximum penetration was found to vary as the square root of the dynamic-pressure ratio and the square root of the total injection nozzle area. Spray cross-section area was linear with maximum penetration. The test results are used to compute injection parameters for the RAM C-3 flight injection experiment.

  18. Fluoropolymer Films Deposited by Argon Ion-Beam Sputtering of Polytetrafluoroethylene

    NASA Technical Reports Server (NTRS)

    Golub, Morton A.; Banks, Bruce A.; Kliss, Mark (Technical Monitor)

    1998-01-01

    The FT-IR, XPS and UV spectra of fluoropolymer films (SPTFE-I) deposited by argon ion-beam sputtering of polytetrafluoroethylene (PTFE) were obtained and compared with prior corresponding spectra of fluoropolymer films (SPTFE-P) deposited by argon rf plasma sputtering of PTFE. Although the F/C ratios for SPTFE-I and -P (1.63 and 1.51) were similar, their structures were quite different in that there was a much higher concentration of CF2 groups in SPTFE-I than in SPTFE-P, ca. 61 and 33% of the total carbon contents, respectively. The FT-IR spectra reflect that difference, that for SPTFE-I showing a distinct doublet at 1210 and 1150 per centimeter while that for SPTFE-P presents a broad, featureless band at ca. 1250 per centimeter. The absorbance of the 1210-per centimeter band in SPTFE-I was proportional to the thickness of the film, in the range of 50-400 nanometers. The SPTFE-I was more transparent in the UV than SPTFE-P at comparable thickness. The mechanism for SPTFE-I formation likely involves "chopping off" of oligomeric segments of PTFE as an accompaniment to "plasma" polymerization of TFE monomer or other fluorocarbon fragments generated in situ from PTFE on impact with energetic Ar ions. Data are presented for SPTFE-I deposits and the associated Ar(+) bombarded PTFE targets where a fresh target was used for each run or a single target was used for a sequence of runs.

  19. Nanoliter volume, high-resolution NMR microspectroscopy using a 60-micron planar microcoil.

    PubMed

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

    1997-11-01

    Previous studies demonstrated the feasibility of using 100-microns inner diameter planar spiral inductors (microcoils) as detectors in 1H nuclear magnetic resonance (NMR) microspectroscopy. However, high-resolution NMR applications were not possible due to poor spectral resolution and low signal-to-noise ratio (SNR). These limitations in performance have now been largely overcome by using a nonconductive liquid fluorocarbon (FC-43) to minimize the effects of susceptibility mismatch between materials, and by carefully optimizing the microcoil geometry for maximum SNR. In this study, liquid samples were loaded into a fused silica capillary (75-microns inner diameter, 147-microns outer diameter). The capillary was positioned 50 microns above a 3.5-turn microcoil so that approximately 1 nL of the sample was present in the sensitive region of the microcoil. The microcoil was fabricated on a gallium arsenide substrate with an inner diameter of 60 microns, an outer diameter of 200 microns, trace width of 10 microns, trace spacing of 10 microns, and trace height of 3 microns. At 5.9 T (250 MHz) in 1H-NMR microspectroscopy experiments using a spectral width of 1 kHz, 4096 sampled data points, and a recovery delay of 1 s, a SNR of 25 (per acquisition) and a spectral linewidth of less than 2 Hz were obtained from a sample of water. These results demonstrate that planar microcoils can be used for high-resolution NMR microspectroscopy. Such coils may also be suitable for localized NMR studies at the cellular level and as detectors in capillary electrophoresis or microbore liquid chromatography. PMID:9353992

  20. Thermal activation of superheated lipid-coated perfluorocarbon drops.

    PubMed

    Mountford, Paul A; Thomas, Alec N; Borden, Mark A

    2015-04-28

    This study explored the thermal conditions necessary for the vaporization of superheated perfluorocarbon nanodrops. Droplets C3F8 and C4F10 coated with a homologous series of saturated diacylphosphatidylcholines were formed by condensation of 4 ?m diameter microbubbles. These drops were stable at room temperature and atmospheric pressure, but they vaporized back into microbubbles at higher temperatures. The vaporization transition was measured as a function of temperature by laser light extinction. We found that C3F8 and C4F10 drops experienced 90% vaporization at 40 and 75 °C, respectively, near the theoretical superheat limits (80-90% of the critical temperature). We therefore conclude that the metastabilty of these phase-change agents arises not from the droplet Laplace pressure altering the boiling point, as previously reported, but from the metastability of the pure superheated fluid to homogeneous nucleation. The rate of C4F10 drop vaporization was quantified at temperatures ranging from 55 to 75 °C, and an apparent activation energy barrier was calculated from an Arrhenius plot. Interestingly, the activation energy increased linearly with acyl chain length from C14 to C20, indicating that lipid interchain cohesion plays an important role in suppressing the vaporization rate. The vaporized drops (microbubbles) were found to be unstable to dissolution at high temperatures, particularly for C14 and C16. However, proper choice of the fluorocarbon and lipid species provided a nanoemulsion that could undergo at least ten reversible condensation/vaporization cycles. The vaporization properties presented in this study may facilitate the engineering of tunable phase-shift particles for diagnostic imaging, targeted drug delivery, tissue ablation, and other applications. PMID:25853278

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

    SciTech Connect

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

    2007-01-15

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

  2. Energy and global climate change: Why ORNL?

    SciTech Connect

    Farrell, M.P.

    1995-12-31

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

  3. Dynamically reconfigurable complex emulsions via tunable interfacial tensions

    NASA Astrophysics Data System (ADS)

    Zarzar, Lauren D.; Sresht, Vishnu; Sletten, Ellen M.; Kalow, Julia A.; Blankschtein, Daniel; Swager, Timothy M.

    2015-02-01

    Emulsification is a powerful, well-known technique for mixing and dispersing immiscible components within a continuous liquid phase. Consequently, emulsions are central components of medicine, food and performance materials. Complex emulsions, including Janus droplets (that is, droplets with faces of differing chemistries) and multiple emulsions, are of increasing importance in pharmaceuticals and medical diagnostics, in the fabrication of microparticles and capsules for food, in chemical separations, in cosmetics, and in dynamic optics. Because complex emulsion properties and functions are related to the droplet geometry and composition, the development of rapid, simple fabrication approaches allowing precise control over the droplets' physical and chemical characteristics is critical. Significant advances in the fabrication of complex emulsions have been made using a number of procedures, ranging from large-scale, less precise techniques that give compositional heterogeneity using high-shear mixers and membranes, to small-volume but more precise microfluidic methods. However, such approaches have yet to create droplet morphologies that can be controllably altered after emulsification. Reconfigurable complex liquids potentially have great utility as dynamically tunable materials. Here we describe an approach to the one-step fabrication of three- and four-phase complex emulsions with highly controllable and reconfigurable morphologies. The fabrication makes use of the temperature-sensitive miscibility of hydrocarbon, silicone and fluorocarbon liquids, and is applied to both the microfluidic and the scalable batch production of complex droplets. We demonstrate that droplet geometries can be alternated between encapsulated and Janus configurations by varying the interfacial tensions using hydrocarbon and fluorinated surfactants including stimuli-responsive and cleavable surfactants. This yields a generalizable strategy for the fabrication of multiphase emulsions with controllably reconfigurable morphologies and the potential to create a wide range of responsive materials.

  4. Infrared laser deposition of Teflon coatings on microstructures

    NASA Astrophysics Data System (ADS)

    Papantonakis, M. R.; HaglundJr., R. F.

    2006-01-01

    Polytetrafluoroethylene (PTFE, trade name Teflon) has a wide range of unique and desirable physical, electrical and chemical properties. Its tribological properties are well-suited to anti-stiction applications, and its chemical inertness commends it as a barrier and passivation layer. However, conventional thin-film techniques are not suited for depositing Teflon films on microstructures. Spin coating is impossible because of the well-known insolubility of PTFE. Plasma polymerization of fluorocarbon monomers, ion beam and rf sputtering produce PTFE films that are deficient in fluorine. Pulsed laser deposition (PLD) using excimer and Ti:sapphire lasers is unsatisfactory because UV or near-IR laser ablation "unzips" the PTFE, and requires high-temperature annealing to re-polymerize the deposited monomeric film. We have demonstrated that a completely dry, vapor-phase coating technique - resonant infrared pulsed laser deposition (RIR-PLD) at a wavelength of 8.26 ?m -produces crystalline, smooth Teflon films at low process temperatures. Indeed, the films as deposited by RIR-PLD exhibit a surprising degree of crystallinity even at room temperature. The stoichiometry and local electronic structure are preserved during the laser vaporization process, as demonstrated by IR absorption and X-ray photoelectron spectroscopy. Films deposited on microscale structures show good adhesion, excellent smoothness, and a high degree of conformability to the structures. We also discuss experiments planned for the near future to compare the tribological properties of the PTFE films deposited by RIR-PLD with those of other tribological coatings. We will also discuss the implementation of RIR-PLD in practical processing schemes for MEMS applications, including the challenge in adapting existing solid-state mid-IR laser technology for this purpose.

  5. CF, CF

    SciTech Connect

    Hebner, G. A.

    2001-01-15

    Laser induced fluorescence was used to measure the spatially resolved CF, CF{sub 2}, and SiF radical density in inductively driven discharges containing fluorocarbon gases. Measurements of the spatially resolved CF density were performed in C{sub 2}F{sub 6}, and CHF{sub 3} containing discharges as functions of inductive power, pressure and bias condition on a silicon substrate. In addition, CF rotational temperatures were calculated, assuming saturated spectra. Measurements of the spatially resolved CF{sub 2} and SiF density were performed in C{sub 4}F{sub 8}, C{sub 2}F{sub 6}, and CHF{sub 3} containing discharges as functions of inductive power, pressure and bias condition. SiF rotational temperatures were also estimated. As the induction coil power was increased, the SiF density in the center (r=0 cm) increased while the CF{sub 2} density decreased and the CF density slightly decreased. In all cases, the radical density in the center of the glow increased with pressure changes from 5 to 30 mTorr while changes in the bias power had little influence on any of the measured radical densities. The spatial distribution of the CF and SiF density peaked in the center of the discharge. The CF{sub 2} density had a local maximum in the center of the plasma with a decreasing density at the edge of the glow. However, the CF{sub 2} density outside the glow region was a factor of 2--6 higher than the density inside the glow region, depending on the gas. CF and SiF rotational temperatures were between 450 and 750 K.

  6. Interactive stereo electron microscopy enhanced with virtual reality

    NASA Astrophysics Data System (ADS)

    Bethel, E. W.; Bastacky, S. J.; Schwartz, Ken

    2002-05-01

    An analytical system is presented that is used to take measurements of objects perceived in stereo image pairs obtained from a scanning electron microscope (SEM). Our system operates by presenting a single stereo view that contains stereo image data obtained form the SEM, along with geometric representations of two types of virtual measurement instruments, a protractor and a caliper. The measurements obtained form this system are an integral part of a medical study evaluating surfactant, a liquid coating the inner surface of the lung which makes possible the process of breathing. Measurements of the curvature and contact angle of submicrom diameter droplets of a fluorocarbon deposited on the surface of airways are performed in order to determine surface tension of the air/liquid interface. This approach has been extended to a microscopic level from the techniques of traditional surface science by measuring submicrometer rather than millimeter diameter droplets, as well as the lengths and curvature of cilia responsible for movement of the surfactant, the airway's protective liquid blanket. An earlier implementation of this approach for taking angle measurements from objects perceived in stereo image pairs using virtual protractor is extended in this paper to include distance measurements and to use a unified view model. The system is built around a unified view model that is derived from microscope-specific parameters, such as focal length, visible area and magnification. The unified view model ensures that the underlying view models and resultant binocular parallax cues are consistent between synthetic and acquired imagery. When the view models are consistent, it is possible to take measurements of features that are not constrained to lie within the projection plane. The system is first calibrated using non-clinical data of known size and resolution. Using the SEM, stereo image pairs of grids and spheres of known resolution are created to calibrate the measurement system. After calibration, the system is used to take distance and angle measurements of clinical specimens.

  7. The Materials Chemistry of Atomic Oxygen with Applications to Anisotropic Etching of Submicron Structures in Microelectronics and the Surface Chemistry Engineering of Porous Solids

    SciTech Connect

    Koontz, S.L.; Leger, L.J.; Wu, C.; Cross, J.B.; Jurgensen, C.W. [Los Alamos National Lab., NM (United States); [Bell Telephone Labs., Inc., Murray Hill, NJ (United States)

    1994-05-01

    Neutral atomic oxygen is the most abundant component of the ionospheric plasma in the low Earth orbit environment (LEO; 200 to 700 kilometers altitude) and can produce significant degradation of some spacecraft materials. In order to produce a more complete understanding of the materials chemistry of atomic oxygen, the chemistry and physics of O-atom interactions with materials were determined in three radically different environments: (1) The Space Shuttle cargo bay in low Earth orbit (the EOIM-3 space flight experiment), (2) a high-velocity neutral atom beam system (HVAB) at Los Alamos National Laboratory (LANL), and (3) a microwave-plasma flowing-discharge system at JSC. The Space Shuttle and the high velocity atom beam systems produce atom-surface collision energies ranging from 0.1 to 7 eV (hyperthermal atoms) under high-vacuum conditions, while the flowing discharge system produces a 0.065 eV surface collision energy at a total pressure of 2 Torr. Data obtained in the three different O-atom environments referred to above show that the rate of O-atom reaction with polymeric materials is strongly dependent on atom kinetic energy, obeying a reactive scattering law which suggests that atom kinetic energy is directly available for overcoming activation barriers in the reaction. General relationships between polymer reactivity with O atoms and polymer composition and molecular structure have been determined. In addition, vacuum ultraviolet photochemical effects have been shown to dominate the reaction of O atoms with fluorocarbon polymers. Finally, studies of the materials chemistry of O atoms have produced results which may be of interest to technologists outside the aerospace industry. Atomic oxygen `spin-off` or `dual use` technologies in the areas of anisotropic etching in microelectronic materials and device processing, as well as surface chemistry engineering of porous solid materials are described.

  8. Remobilizing surfactant retarded fluid particle interfaces. I. Stress-free conditions at the interfaces of micellar solutions of surfactants with fast sorption kinetics

    SciTech Connect

    Stebe, K.J.; Lin, S.; Maldarelli, C. (The Levich Institute, Department of Chemical Engineering, City College of New York, New York, New York 10031 (US))

    1991-01-01

    Surfactant molecules adsorb onto the interfaces of moving fluid particles and are convected to regions in which the surface flow converges. Accumulation of surfactant in these regions creates interfacial tension gradients that retard the surface flow. In this study it is argued theoretically and demonstrated experimentally that fluid movement on the surface of a drop or bubble can remain unhindered in the presence of a single adsorbed surfactant if, relative to the convective rate of transport of adsorbed surfactant along the surface, desorption is fast, and the bulk concentration is high enough so that diffusion away from the particle is fast. For this circumstance, a uniform surface concentration of surfactant is maintained, and no gradients in surface tension arise to retard the surface velocity. The fluid particle flow behaves as it would in the absence of surfactant save that it has a reduced, uniform surface tension. The remobilization of surfactant-laden interfaces of fluid particles is demonstrated experimentally in a three-phase periodic slug flow in a capillary tube in which a train of alternating air and aqueous slugs ride on an annular wetting film of fluorocarbon oil. Surfactant, dissolved in the aqueous slug phase, adsorbs onto and retards the aqueous--oil interface. The hydrodynamics of this flow is such that small changes in the mobility of this interface create large shear rates in the oil layer. This significantly increases the pressure drop required to drive the slug train at constant velocity. Three surface adsorbers are used to demonstrate surface remobilization: The polyethoxy, nonionic surfactants Triton X-100 and Brij-35, which have fast desorption kinetics and do not retard the surface flow at high concentrations and, as a counter example, the desorption hindered protein bovine serum albumin, which is shown to be unable to remobilize an interface even at high concentration.

  9. Remobilizing surfactant retarded fluid particle interfaces. I. Stress-free conditions at the interfaces of micellar solutions of surfactants with fast sorption kinetics

    NASA Astrophysics Data System (ADS)

    Stebe, Kathleen J.; Lin, Shi-Yow; Maldarelli, Charles

    1991-01-01

    Surfactant molecules adsorb onto the interfaces of moving fluid particles and are convected to regions in which the surface flow converges. Accumulation of surfactant in these regions creates interfacial tension gradients that retard the surface flow. In this study it is argued theoretically and demonstrated experimentally that fluid movement on the surface of a drop or bubble can remain unhindered in the presence of a single adsorbed surfactant if, relative to the convective rate of transport of adsorbed surfactant along the surface, desorption is fast, and the bulk concentration is high enough so that diffusion away from the particle is fast. For this circumstance, a uniform surface concentration of surfactant is maintained, and no gradients in surface tension arise to retard the surface velocity. The fluid particle flow behaves as it would in the absence of surfactant save that it has a reduced, uniform surface tension. The remobilization of surfactant-laden interfaces of fluid particles is demonstrated experimentally in a three-phase periodic slug flow in a capillary tube in which a train of alternating air and aqueous slugs ride on an annular wetting film of fluorocarbon oil. Surfactant, dissolved in the aqueous slug phase, adsorbs onto and retards the aqueous-oil interface. The hydrodynamics of this flow is such that small changes in the mobility of this interface create large shear rates in the oil layer. This significantly increases the pressure drop required to drive the slug train at constant velocity. Three surface adsorbers are used to demonstrate surface remobilization: The polyethoxy, nonionic surfactants Triton X-100 and Brij-35, which have fast desorption kinetics and do not retard the surface flow at high concentrations and, as a counter example, the desorption hindered protein bovine serum albumin, which is shown to be unable to remobilize an interface even at high concentration.

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

    SciTech Connect

    Jordan, A.; Frank, H. [Univ. of Bayreuth (Germany)] [Univ. of Bayreuth (Germany)

    1999-02-15

    The partly halogenated C{sub 2}-hydro(chloro)fluorocarbons (HFC, HCFC) 1,1,1-trifluoro-2,2-dichloroethane (HCFC-123), 1,1,1,2-tetrafluoro-2-chloroethane (HCFC-124), and 1,1,1,2-tetrafluoroethane (HFC-134a) are CFC substitutes found at increasing levels in the atmosphere. Trifluoroacetate (TFA) is an atmospheric degradation product of these compounds and due to its persistence its potential accumulation in some aquatic ecosystems is a matter of environmental concern. The present study was undertaken to determine the present-days base level of environmental TFA and whether model calculations are in line with the actual data. Average levels of about 120 ng L{sup {minus}1} as predicted for the year 2010 are found in rain in Germany already now, slightly higher than in rain collected in Switzerland or Nevada. In the major rivers in Germany, TFA is present at average concentrations of 140 ng L{sup {minus}1}. In air, levels of 45--60 pg m{sup {minus}3} have been found in Central Europe. Between March 1995 and September 1996, a period of substantial increase in atmospheric HFC-134a mixing ratio, the TFA concentrations in air and precipitation did not significantly increase. TFA is absent in old groundwater samples, and in river water from remote locations, concentrations are low. These data suggest that the total TFA in both compartments exceeds the formation potential of currently known sources, that TFA in atmosphere and rain is regionally associated with industrial or population density, and that other unresolved sources must contribute to the present concentrations.

  11. Fracture and damage evolution of fluorinated polymers

    SciTech Connect

    Brown, E. N. (Eric N.); Rae, P. (Philip); Orler, E. B. (E. Bruce); Thissell, W. R. (W. Richards); Dattelbaum, D. M. (Dana M.)

    2004-01-01

    Fluoropolymers are often semi-crystalline in nature, with their linear chains forming complicated phases near room temperature and ambient pressure. The most widely used fluorocarbon polymer for engineering applications is polytetrafluoroethylene (PTFE), due to its extremely low coefficient of friction, outstanding resistance to corrosion, and excellent electrical properties. The phase structure of PTFE is complex with four well-characterized crystalline phases (three observed at atmospheric pressure) and substantial molecular motion well below the melting point. The first-order transition at 19 C between phases II and IV is an unraveling in the helical conformation. Further rotational disordering and untwisting of the helices occurs above 30 C giving way to phase I. The mechanical behavior, including fracture and damage evolution, of PTFE depends on the chain and segment motions dictated by crystalline phase microstructure. The presence of three unique phases at ambient pressure near room temperature implies that failure during standard operating conditions may be strongly dependent on the phase. This paper presents a preliminary study of fracture and damage evolution in PTFE with the effects of temperature-induced phase on fracture mechanisms. The quasi-static fracture of PTFE in the atmospheric pressure regime, over a range of temperatures, was found to be strongly phase dependent: phase II exhibits brittle-fracture, phase IV displays ductile-fracture with crazing and some stable crack growth, and plastic flow dominates phase 1. The bulk failure properties are correlated to failure mechanisms through fractography of the fracture surfaces (optical microscopy and scanning electron microscopy (SEM)).

  12. Evaluation of ceramic and polymeric materials for use in engineered barrier systems

    SciTech Connect

    Fullam, H.T.; Skiens, W.E.

    1980-01-01

    Ceramic materials evaluated in the screening studies were Al/sub 2/O/sub 3/ (99.8%), mullite, vitreous silica, BaTiO/sub 3/, CaTiO/sub 3/, CaZrO/sub 3/, CaTiSiO/sub 5/, TiO/sub 2/, ZrSiO/sub 4/, basalt, Pyroceram 9617, and Marcor code 9658 machinable glass ceramic. One grade of graphite (Toyotanso IB-11) was also evaluated. Demineralized water, a synthetic Hanford groundwater, and a synthetic NaCl brine solution were used in the screening tests. Demineralized water was used in all five of the leach tests, but the other solutions were only used in the static leach tests at 150 and 250/sup 0/C. Based on the results obtained, graphite appears to be the most leach resistant of the materials tested with the two grades of alumina being the best of the ceramic materials. Titanium dioxide and ZrO/sub 2/ are the most leach resistant of the remaining materials. Candidate materials from all three general classes of polymers (thermoplastics, thermosets, and elastomers) were considered in the selection of materials. Selected groups of polymers were tested in the flowing autoclave at 150, 200, and 250/sup 0/C with some polymers being further tested at the next higher temperature. Next, selected samples were exposed to gamma radiation. These samples were then submitted for tensile and elongation measurements. Selected samples which appeared promising from both autoclave and radiation testing were further evaluated by impact tests. The materials that appeared most promising after autoclave testing were the EPDM rubbers, polyphenylene sulfide, poly(ethylene-tetrafluoroethylene) copolymer, and polyfurfuryl alcohol. The radiation dose had little effect on polyfurfuryl alcohol and polyphenylene sulfide samples; very significant decreases in elongation were observed for the fluorocarbon copolymer and the EPDM rubbers. While the polyphenylene sulfide and polyfurfuryl alcohol showed little change in impact strength, poly(ethylene-tetrafluoroethylene) decreased in impact strength.

  13. Comparison of model results transporting the odd nitrogen family with results transporting separate odd nitrogen species

    SciTech Connect

    Douglass, A. R.; Jackman, C. H.; Stolarski, R. S.

    1989-07-20

    We have developed a fast two-dimensional residual circulation stratospheric model. In order to calculate possible effects of long-term changes for trace gases for a large number of scenarios and to examine the model sensitivities to dynamical and photochemical assumptions and inputs, the model is designed to minimize computer requirements. The species continuity equations are solved using process splitting, that is, by successively applying the operators associated with advective changes with photochemical and diffusive forcing. The first study undertaken with this model concerns family chemistry approximations, in which groups of species are related by photochemical equilibrium assumptions and transported as one species. These assumptions are tested by comparing results for the family transport model (FTM), in which odd nitrogen (NO/sub y/=N+NO+NO/sub 2/+NO/sub 3/+2N/sub 2/O/sub 5/ +HO/sub 2/NO/sub 2/+ClONO/sub 2/+HNO/sub 3/) is transported as a family, with the results for a separate transport model (STM) in which HNO/sub 3/, HO/sub 2/NO/sub 2/, ClONO/sub 2/ and N/sub 2/O/sub 5/ are transported separately from NO/sub /ital x//=N+NO+NO/sub 2/+NO/sub 3/. Two cases are considered: (1) a current atmosphere annual cycle; and (2) a typical scenario for increased fluorocarbons, methane, and nitrous oxide. Although there are differences in odd nitrogen species partitioning, especially at high latitudes, the calculated O/sub 3/ distributions are nearly identical. For the perturbation scenario the annual average column ozone change and its temporal and spatial characteristics are nearly the same for the FTM and the STM. /copyright/ American Geophysical Union 1989

  14. Improved solar-collector sealants. Final report, October 1980-July 1982

    SciTech Connect

    Frost, L.W.; Scala, L.C.; Alvino, W.M.; Bower, G.M.

    1982-08-31

    In a program to evaluate materials for use as sealants and gaskets for flat-plate solar collectors, a total of 91 materials were examined. They included the following types: 10 commercial silicone caulks, 9 commercial fluoroelastomer preformed seals; 1 commercial fluorosilicone preformed seal, 6 commercial EPDM preformed seals, 8 commercial silicone preformed seals, 6 commercial acrylic preformed seals, 1 commercial ethylene-acrylic preformed seal, 1 commercial chlorobutyl preformed seal, 5 experimental silicone preformed seals, and 44 experimental fluorocarbon-silicone preformed seals. Properties measured were tensile strength, modulus, and elongation; compression set at 150/sup 0/C and at -10/sup 0/C; hardness, and weight loss. In addition, the more promising materials were subjected to long-term aging at several temperatures, with periodic measurements of tensile properties, weight loss, and compression set. Rough estimates based on extrapolation of compression set curves suggest a 10 year continuous service temperature of 145/sup 0/C for the best of them. The best of the silicone preformed seal materials gave a continuous 10 year life temperature of 116/sup 0/C, based on compression set, and of 98/sup 0/C, based on tensile strength and elongation. Four other silicones were in the range of 96 to 108/sup 0/C, based on compression set, which is probably the most significant property for this application. The best of the EPDM materials had a continuous 10 year life temperatures of 100/sup 0/C, based on average tensile properties, and 72/sup 0/C based on compression set. The best of the sealant caulks had a continuous 10 year life temperature of 95/sup 0/C, based on an end of life criterion of 3% weight loss.

  15. Integrated framework for the flux calculation of neutral species inside trenches and holes during plasma etching

    SciTech Connect

    Kokkoris, George; Boudouvis, Andreas G.; Gogolides, Evangelos [Institute of Microelectronics, NCSR 'Demokritos', Aghia Paraskevi, Attiki 15310 (Greece); School of Chemical Engineering, National Technical University of Athens, Zographou Campus, Attiki 15780 (Greece); Institute of Microelectronics, NCSR 'Demokritos', Aghia Paraskevi, Attiki 15310 (Greece)

    2006-11-15

    An integrated framework for the neutral flux calculation inside trenches and holes during plasma etching is described, and a comparison between the two types of structure in a number of applications is presented. First, a detailed and functional set of equations for the neutral and ion flux calculations inside long trenches and holes with cylindrical symmetry is explicitly formulated. This set is based on early works [T. S. Cale and G. B. Raupp, J. Vac. Sci. Technol. B 8, 1242 (1990); V. K. Singh et al., J. Vac. Sci. Technol. B 10, 1091 (1992)], and includes new equations for the case of holes with cylindrical symmetry. Second, a method for the solution of the respective numerical task, i.e., one or a set of linear or nonlinear integral equations, is described. This method includes a coupling algorithm with a surface chemistry model and resolves the singularity problem of the integral equations. Third, the fluxes inside trenches and holes are compared. The flux from reemission is the major portion of the local flux at the bottom of both types of structure. The framework is applied in SiO{sub 2} etching by fluorocarbon plasmas to predict the increased intensity of reactive ion etching lag in SiO{sub 2} holes compared to trenches. It is also applied in deep Si etching: By calculating the flux of F atoms at the bottom of very high aspect ratio (up to 150) Si trenches and holes during the gas chopping process, the aspect ratio at which the flux of F atoms is eliminated and etching practically stops is estimated.

  16. Electrothermodynamic (etd) power converter

    SciTech Connect

    Marks, A.M.

    1983-07-26

    These inventions relate to novel advances in Electrothermodynamics (ETD), also known as charged aerosol, heat/electric power generators: (1) A new more efficient, compact converging/diverging configuration comprising a torus of revolution (TORON) used with a gas flywheel. (2) A ''Method II'' two-fluid mixed flow ejector/converter in a gas flywheel loop employing a primary steam or a high molecular weight driver jet such as a fluorocarbon containing charged aerosol water droplets and a low molecular weight carrier gas such as hydrogen or helium with an electro-negative gas additive, in a Rankine cycle including a vapor/gas and liquid separator with a bypass to the ejector/converter loop. (3) A ''Method III'' two-fluid mixed flow comprising a supersonic jet expanding conically within a subsonic flow, separated by a boundary layer in which the charged aerosol forms downstream of the orifice, at a cross section of at least 100 times the orifice section; and in which the electric charge density of the charged aerosol decreases along the jet axis, whereby substantially all of the kinetic power of the jet is converted to electric power within the jet, there being no ejector. (4) An array of supersonic jets utilizing Method III. (5) An array of supersonic jets utilizing Method III without separating duct walls in which ''convection cells'' provide return flows, forming a plurality of TORON configurations. (6) A supercritical Rankline cycle in a single stage employing Method III. (7) A method IV two-fluid cycle uses charged aerosols in an inert gas and operates on an Ericsson-type cycle. (8) Optimum operating conditions are defined for Methods II, III, and IV. (9) A high potential emitter is employed with a grounded body, and a sapphire tube sealed to metal by a new technique provides an insulating duct for the high temperature, high pressure vapor.

  17. Ion and neutral species in C{sub 2}F{sub 6} and CHF{sub 3} dielectric etch discharges

    SciTech Connect

    Jayaraman, R.; McGrath, R.T. [The Pennsylvania State University, University Park, Pennsylvannia 16802 (United States)] [The Pennsylvania State University, University Park, Pennsylvannia 16802 (United States); Hebner, G.A. [Sandia National Laboratories, Albuquerque, New Mexico (United States)] [Sandia National Laboratories, Albuquerque, New Mexico (United States)

    1999-07-01

    Relative concentrations of reactive ions, neutral radicals, resist and substrate etch products have been measured in dielectric etch chemistries using an uncollided beam mass spectrometer/ion extractor from Hiden Analytical. Analysis techniques employed include both electron impact ionization and dissociative ionization of neutral gas, and potential bias extraction of positive ions from the reactor discharge volume. Measurements were made in C{sub 2}F{sub 6} and CHF{sub 3} discharges in an inductively coupled plasma (GEC) research reactor operating with power densities, pressures, gas compositions and wafer materials typical of those found in etch processing tools. Wafer substrates investigated included blanket silicon wafers and silicon wafers with varying amounts of photoresist coverage of the surface (20{percent}, 80{percent} and 100{percent}). In C{sub 2}F{sub 6} discharges CF{sub 3}{sup +} was consistently the dominant fluorocarbon ion present, in agreement with published cross sections for dissociative ionization. Smaller concentrations of CF{sup +}, CF{sub 2}{sup +}, and C{sub 2}F{sub 5}{sup +}, were also observed, though the dissociative ionization production of C{sub 2}F{sub 5}{sup +} was a factor of 5 smaller than would be expected from published cross section values. The presence of photoresist, even in small amounts, was found to produce marked changes in the discharge composition. For example, in C{sub 2}F{sub 6} discharges, concentrations of SiF{sub x} etch products relative to concentrations of C{sub x}F{sub y} species were notably diminished and larger concentrations of water vapor were observed when resist was present. In CHF{sub 3} discharges, CF{sub 3}{sup +} and CHF{sub 2}{sup +} were found to be the main species present, along with smaller concentrations of CF{sub 2}{sup +}, CF{sup +}, CHF{sup +}, CH{sup +} and F{sup +}. {copyright} {ital 1999 American Vacuum Society.}

  18. Ion and Neutral Species in C(2)F(6) and CHF(3) Dielectric Etch Discharges

    SciTech Connect

    Hebner, G.; Jayaraman, R.P.; McGrath, R.T.

    1999-01-26

    Relative concentrations of reactive ions, neutral radicals, resist and substrate etch products have been measured in dielectric etch chemistries using an uncollided beam mass spectrometer / ion extractor from Hiden Analytical. Analysis techniques employed include both electron impact ionization and dissociative ionization of neutral gas, and potential bias extraction of positive ions from the reactor discharge volume. Measurements were made in C{sub 2}F{sub 6} and CHF{sub 3} discharges in an inductively coupled plasma (ICP-GEC) research reactor operating with power densities, pressures, gas compositions and wafer materials typical of those found in etch processing tools. Wafer substrates investigated included blanket silicon wafers and silicon wafers with varying amounts of photo-resist coverage of the surface (20%, 80% and 100%). In C{sub 2}F{sub 6} discharges CF{sub 3}{sup +} was consistently the dominant fluorocarbon ion present, in agreement with published cross sections for dissociative ionization [ 1,2.3,4.5,6]. Smaller concentrations of CF+, CF{sub 2}{sup -}, and C{sub 2}F{sub 5}{sup +}, were also observed, though the dissociative ionization production of C{sub 2}F{sub 5}{sup +} was a factor of five smaller than would be expected from published cross section values. The presence of photo-resist, even in small amounts, was found to produce marked changes in the discharge composition. For example in C{sub 2}F{sub 6} discharges, concentrations of SiF{sub x} etch products relative to concentrations of C{sub x}F{sub y} species were notably diminished and larger concentrations of water vapor were observed when resist was present. In CHF{sub 3} discharges, CF{sub 3}{sup +} and CHF{sub 2}{sup +} were found to be the main species present, along with smaller concentrations of CF{sub 2}{sup +}, CF{sup +}, CHF{sup +}, CH{sup +} and F{sup -}.

  19. Surface Analysis for Selective SiO2 Etching by Reflectance Photoelastic Modulated Fourier Transform Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Doh, Hyun-Ho; Chu, Changwoong; Chi, Kyeong-Koo; Moon, Joo-Tae

    2001-10-01

    Photoelastic modulated fourier transform infrared (PEM FTIR) spectroscopy has been used to study the bonding structure and compositions of fluorocarbon films generated during etching with CHF3/CO surface wave plasma (SWP). The C=C (stretching vibration mode at 1600 cm-1), C-C (940 cm-1), C-F (1032, 1164, 1260, 1291 cm-1), {=}C--H (780 cm-1) and C=O (1790 cm-1) peaks on the polymer films were identified using reflectance PEM FTIR@. In addition to the peak assignment, the C-F spectra were fitted to three peaks—1280, 1250, 1200 cm-1, with Gaussian splitting, respectively. Comparing the etching results with the variation of FTIR spectra, it was found that the selectivity of SiO2 to poly-Si and photoresist with CO mixing ratio to CHF3 is correlated to the area ratio of [C=C]/[C-F] and [C=C]/[C=O]. The XPS result was also compared to reflectance PEM FTIR data to reveal the availability of reflectance PEM FTIR application. It was confirmed that there existed a good agreement between PEM FTIR and XPS data. When we integrated all the results from PEM FTIR, XPS and optical emission spectroscopy (OES), we found that the element of the C=C bond on the polymer surface played an important role as an etch inhibitor. The reflectance PEM FTIR measurement on the etched surface is considered to lead to an understanding the properties of polymer films generated during oxide etching.

  20. Influences of damage and contamination from reactive ion etching on selective tungsten deposition in a low-pressure chemical-vapor-deposition reactor

    NASA Astrophysics Data System (ADS)

    Chang, Kow-Ming; Yeh, Ta-Hsun; Wang, Shih-Wei; Li, Chii-Horng

    1996-09-01

    Reactive ion etching (RIE) used in contact hole formation can result in damage and contamination of the underlying silicon substrate. In this work, influences of these phenomena on selective tungsten deposition in a low-pressure chemical-vapor-deposition reactor have been studied. The damage was generated because of ion bombardment and radiation-induced bonding changes in silicon lattices. It causes large Si consumption, rough W/Si interface during tungsten deposition, and large leakage current of W/Si Schottky structure. Simultaneously, contamination occurred with two forms of residual layers and impurity permeation layers in fluorocarbon-based RIE chemistries. The CF4/CHF3/O2 RIE of oxide produces the SiFxCyOz complex layers deposited on the sidewall and on the Si surface as well as the embedding of impurities such as F and C in the Si substrate. The creep-up, selectivity loss, lateral encroachment, high W film resistivity, and rough W/Si interface have been observed in the contaminated samples. Accordingly, a post-RIE etching technique used to remove the damage and contaminants before tungsten growth has been developed. A CF4/O2 plasma etching followed with an O2 plasma ashing step exhibits the capability of efficient surface cleaning. The excellent characteristics of W films such as elimination of encroachment and creep-up, low selectivity loss (i.e., 0.25 pcs/cm2), low resistivity of W films, smooth W/Si interface, and very low leakage current of W/Si contacts are thus obtained.