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Sample records for acetylene partial pressure

  1. Vapor pressures of acetylene at low temperatures

    NASA Technical Reports Server (NTRS)

    Masterson, C. M.; Allen, John E., Jr.; Kraus, G. F.; Khanna, R. K.

    1990-01-01

    The atmospheres of many of the outer planets and their satellites contain a large number of hydrocarbon species. In particular, acetylene (C2H2) has been identified at Jupiter, Saturn and its satellite Titan, Uranus and Neptune. In the lower atmospheres of these planets, where colder temperatures prevail, the condensation and/or freezing of acetylene is probable. In order to obtain accurate models of the acetylene in these atmospheres, it is necessary to have a complete understanding of its vapor pressures at low temperatures. Vapor pressures at low temperatures for acetylene are being determined. The vapor pressures are measured with two different techniques in order to cover a wide range of temperatures and pressures. In the first, the acetylene is placed in a sample tube which is immersed in a low temperature solvent/liquid nitrogen slush bath whose temperature is measured with a thermocouple. The vapor pressure is then measured directly with a capacitance manometer. For lower pressures, a second technique which was called the thin-film infrared method (TFIR) was developed. It involves measuring the disappearance rate of a thin film of acetylene at a particular temperature. The spectra are then analyzed using previously determined extinction coefficient values, to determine the disappearance rate R (where R = delta n/delta t, the number of molecules that disappear per unit time). This can be related to the vapor pressure directly. This technique facilitates measurement of the lower temperatures and pressures. Both techniques have been calibrated using CO2, and have shown good agreement with the existing literature data.

  2. Pressure-induced Polymerization in Substituted Acetylenes

    NASA Astrophysics Data System (ADS)

    Chellappa, Raja; Dattelbaum, Dana; Sheffield, Stephen; Robbins, David

    2011-06-01

    A fundamental understanding of shock-induced chemical reactions in organics is still lacking and there are limited studies devoted to determining reaction mechanisms, evolution of bonding, and effect of functional group substitutions. The fast timescale of reactions occurring during shock compression create significant experimental challenges (diagnostics) to fully quantify the mechanisms involved. Static compression provides a complementary route to investigate the equilibrium phase space and metastable intermediates during high pressure chemistry, although at a much slower timescale. In this study, we present our results from our ongoing high pressure in situ synchrotron x-ray diffraction and vibrational spectroscopy experiments on substituted acetylenes: tert-butyl acetylene [TBA: (CH3)3 -C ≡CH] and ethynyl trimethylsilane [ETMS: (CH3)3 -Si ≡CH]. We observed that the onset pressure of chemical reactions (at room temperature) in these compounds is significantly higher in static compression (TBA: 11 GPa and ETMS: 26 GPa) when compared to shock input pressures (TBA: 6.1 GPa and ETMS: 6.6 GPa). The products were polymeric in nature, recovered to ambient conditions with little degradation and fully characterized using spectroscopy, calorimetry, and other techniques to identify reaction mechanisms. LDRD-DR (PI: Dana Dattelbaum)

  3. Oxygen partial pressure sensor

    DOEpatents

    Dees, D.W.

    1994-09-06

    A method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured. 1 fig.

  4. Oxygen partial pressure sensor

    DOEpatents

    Dees, Dennis W.

    1994-01-01

    A method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured.

  5. Oxygen transport through polyethylene terephthalate (PET) coated with plasma-polymerized acetylene at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Wemlinger, Erik; Pedrow, Patrick; Garcia-Pérez, Manuel; Sablani, Shyam

    2011-10-01

    Moser et al. have shown that oxygen transport through polyethyleneterephthalate (PET) is reduced by a factor of up to 120 when, at reduced pressure, hydrogenated amorphous carbon film with thickness less than 100 nm is applied to the PET substrate. Our work includes using atmospheric pressure cold plasma to grow a plasma-polymerized acetylene film on PET substrate and measuring reductions in oxygen transport. The reactor utilizes corona discharges and is operated at 60 Hz with a maximum voltage of 10 kV RMS. Corona streamers emanate from an array of needles with an average radius of curvature of 50 μm. The reactor utilizes a cylindrical reaction chamber with a vertical orientation such that argon carrier gas and acetylene precursor gas are introduced at the top then pass through the cold plasma activation zone and then through a grounded stainless steel mesh. Acetylene radicals are incident on the PET substrate and form plasma-polymerized acetylene film. Moser et al. have shown that oxygen transport through polyethyleneterephthalate (PET) is reduced by a factor of up to 120 when, at reduced pressure, hydrogenated amorphous carbon film with thickness less than 100 nm is applied to the PET substrate. Our work includes using atmospheric pressure cold plasma to grow a plasma-polymerized acetylene film on PET substrate and measuring reductions in oxygen transport. The reactor utilizes corona discharges and is operated at 60 Hz with a maximum voltage of 10 kV RMS. Corona streamers emanate from an array of needles with an average radius of curvature of 50 μm. The reactor utilizes a cylindrical reaction chamber with a vertical orientation such that argon carrier gas and acetylene precursor gas are introduced at the top then pass through the cold plasma activation zone and then through a grounded stainless steel mesh. Acetylene radicals are incident on the PET substrate and form plasma-polymerized acetylene film. E.M. Moser, R. Urech, E. Hack, H. Künzli, E. Müller, Thin

  6. Low pressure R.F. plasma reactions in light hydrocarbons. Ethylene and acetylene

    NASA Astrophysics Data System (ADS)

    Canepa, Pietro; Castello, Gianrico; Nicchia, Mario; Munari, Stelio

    The results obtained in the plasmolysis of ethylene and acetylene in an inductively coupled radiofrequency glow discharge are reported. A static system at a constant initial pressure of 0.5 torr and input power of 50 W was used; the gaseous and polymeric products were evaluated and compared with previous data on ethane plasmolysis and other available literature data. The decomposition products of ethylene were similar to those obtained during the plasmolysis of ethane, with a different distribution and a smaller initial increase of the total pressure. The total pressure of acetylene quickly decreased to near zero value at small specific energy, due to rapid polymerization. No gaseous products were detected, except hydrogen and traces of diacetylene.

  7. Deposition of Functional Coatings from an Acetylene-Containing Plasma at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Plevako, F. V.; Gorbatov, S. V.; Davidovich, P. A.; Prikhod‧ko, E. M.; Shushkov, S. V.; Krul‧, L. P.; Butovskaya, G. V.; Shakhno, O. V.; Gusakova, S. V.; Korolik, O. V.; Mazanik, A. V.

    2016-03-01

    Properties of thin coatings formed on polymer and glass substrates by plasma-enhanced chemical vapor deposition from a mixture of nitrogen with acetylene at atmospheric pressure were investigated. It was established that chemically stable transparent films with a mass ratio of fixed carbon and nitrogen C:N ~ 2:1 are formed on the surface of these substrates. When the deposition time was increased, arrays of dendrite-like structures were formed on the substrates.

  8. Cold-atmospheric pressure plasma polymerization of acetylene on wood flour for improved wood plastics composites

    NASA Astrophysics Data System (ADS)

    Lekobou, William; Pedrow, Patrick; Englund, Karl; Laborie, Marie-Pierre

    2009-10-01

    Plastic composites have become a large class of construction material for exterior applications. One of the main disadvantages of wood plastic composites resides in the weak adhesion between the polar and hydrophilic surface of wood and the non-polar and hydrophobic polyolefin matrix, hindering the dispersion of the flour in the polymer matrix. To improve interfacial compatibility wood flour can be pretreated with environmentally friendly methods such as cold-atmospheric pressure plasma. The objective of this work is therefore to evaluate the potential of plasma polymerization of acetylene on wood flour to improve the compatibility with polyolefins. This presentation will describe the reactor design used to modify wood flour using acetylene plasma polymerization. The optimum conditions for plasma polymerization on wood particles will also be presented. Finally preliminary results on the wood flour surface properties and use in wood plastic composites will be discussed.

  9. Partial pressure analysis of plasmas

    SciTech Connect

    Dylla, H.F.

    1984-11-01

    The application of partial pressure analysis for plasma diagnostic measurements is reviewed. A comparison is made between the techniques of plasma flux analysis and partial pressure analysis for mass spectrometry of plasmas. Emphasis is given to the application of quadrupole mass spectrometers (QMS). The interface problems associated with the coupling of a QMS to a plasma device are discussed including: differential-pumping requirements, electromagnetic interferences from the plasma environment, the detection of surface-active species, ion source interactions, and calibration procedures. Example measurements are presented from process monitoring of glow discharge plasmas which are useful for cleaning and conditioning vacuum vessels.

  10. Soot Formation in Laminar Acetylene/Air Diffusion Flames at Atmospheric Pressure. Appendix C

    NASA Technical Reports Server (NTRS)

    Xu, F.; Faeth, G. M.; Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

    2000-01-01

    The flame structure and soot-formation (soot nucleation and growth) properties of axisymmetric laminar coflowing jet diffusion flames were studied experimentally. Test conditions involved acetylene-nitrogen jets burning in coflowing air at atmospheric pressure. Measurements were limited to the axes of the flames and included soot concentrations, soot temperatures, soot structure, major gas species concentrations, radical species (H, OH, and O) concentrations, and gas velocities. The results show that as distance increases along the axes of the flames, detectable soot formation begins when significant H concentrations are present, and ends when acetylene concentrations become small. Species potentially associated with soot oxidation-O2, CO2, H2O, O, and OH-are present throughout the soot-formation region so that soot formation and oxidation proceed at the same time. Strong rates of soot growth compared to soot nucleation early in the soot-formation process, combined with increased rates of soot nucleation and oxidation as soot formation proceeds, causes primary soot particle diameters to reach a maximum relatively early in the soot-formation process. Aggregation of primary soot particles proceeds, however, until the final stages of soot oxidation. Present measurements of soot growth (corrected for soot oxidation) in laminar diffusion flames were consistent with earlier measurements of soot growth in laminar premixed flames and exhibited encouraging agreement with existing hydrogen-abstraction/carbon-addition (HACA) soot growth mechanisms in the literature that were developed based on measurements within laminar premixed flames. Measured primary soot particle nucleation rates in the present laminar diffusion flames also were consistent with corresponding rates measured in laminar premixed flames and yielded a crude correlation in terms of acetylene and H concentrations and the temperature.

  11. Soot Formation in Laminar Acetylene/Air Diffusion Flames at Atmospheric Pressure. Appendix J

    NASA Technical Reports Server (NTRS)

    Xu, F.; Faeth, G. M.; Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

    2001-01-01

    The flame structure and soot-formation (soot nucleation and growth) properties of axisymmetric laminar coflowing jet diffusion flames were studied experimentally. Test conditions involved acetylene-nitrogen jets burning in coflowing air at atmospheric pressure. Measurements were limited to the axes of the flames and included soot concentrations, soot temperatures, soot structure, major gas species concentrations, radical species (H, OH, and O) concentrations, and gas velocities. The results show that as distance increases along the axes of the flames, detectable soot formation begins when significant H concentrations are present, and ends when acetylene concentrations become small. Species potentially associated with soot oxidation--O2, CO2, H2O, O, and OH-are present throughout the soot-formation region so that soot formation and oxidation proceed at the same time. Strong rates of soot growth compared to soot nucleation early in the soot-formation process, combined with increased rates of soot nucleation and oxidation as soot formation proceeds, causes primary soot particle diameters to reach a maximum relatively early in the soot-formation process. Aggregation of primary soot particles proceeds, however, until the final stages of soot oxidation. Present measurements of soot growth (corrected for soot oxidation) in laminar diffusion flames were consistent with earlier measurements of soot growth in laminar premixed flames and exhibited encouraging agreement with existing hydrogen-abstraction/carbon-addition (HACA) soot growth mechanisms in the literature that were developed based on measurements within laminar premixed flames. Measured primary soot particle nucleation rates in the present laminar diffusion flames also were consistent with corresponding rates measured in laminar premixed flames and yielded a crude correlation in terms of acetylene and H concentrations and the temperature.

  12. Soot Formation in Laminar Acetylene/Air Diffusion Flames at Atmospheric Pressure. Appendix H

    NASA Technical Reports Server (NTRS)

    Xu, F.; Faeth, G. M.; Yuan, Z.-G. (Technical Monitor); Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

    2001-01-01

    The flame structure and soot-formation (soot nucleation and growth) properties of axisymmetric laminar coflowing jet diffusion flames were studied experimentally. Test conditions involved acetylene-nitrogen jets burning in coflowing air at atmospheric pressure. Measurements were limited to the axes of the flames and included soot concentrations, soot temperatures, soot structure, major gas species concentrations, radical species (H, OH, and O) concentrations, and gas velocities. The results show that as distance increases along the axes of the flames, detectable soot formation begins when significant H concentrations are present, and ends when acetylene concentrations become small. Species potentially associated with soot oxidation-O2, CO2, H2O, O, and OH-are present throughout the soot-formation region so that soot formation and oxidation proceed at the same time. Strong rates of soot growth compared to soot nucleation early in the soot-formation process, combined with increased rates of soot nucleation and oxidation as soot formation proceeds, causes primary soot particle diameters to reach a maximum relatively early in the soot-formation process. Aggregation of primary soot particles proceeds, however, until the final stages of soot oxidation. Present measurements of soot growth (corrected for soot oxidation) in laminar diffusion flames were consistent with earlier measurements of soot growth in laminar premixed flames and exhibited encouraging agreement with existing hydrogen-abstraction/carbon-addition (HACA) soot growth mechanisms in the literature that were developed based on measurements within laminar premixed flames. Measured primary soot particle nucleation rates in the present laminar diffusion flames also were consistent with corresponding rates measured in laminar premixed flames and yielded a crude correlation in terms of acetylene and H concentrations and the temperature.

  13. Negative ion density in magnetically confined low-pressure argon-acetylene plasmas using laser-induced photodetachment

    NASA Astrophysics Data System (ADS)

    Margot, Joelle; Al Makdessi, Georges; Hamdan, Ahmad; Clergereaux, Richard

    2015-09-01

    In plasmas generated in reactive gases such as silane and acetylene, dust particles can spontaneously form provided the residence time of the precursors is large enough for allowing volume interactions to dominate over surface interactions. In discharges at intermediate pressure (e.g. 100 mTorr), anions are considered to be the most likely precursors to dust particles formation. In the present work, we examine the negative ion density in very low pressure conditions, namely 1-10 mTorr. For this purpose, we investigate magnetized dusty plasmas produced in argon-acetylene mixtures in which dust particles have been observed. The negative ion density is measured using a laser photodetachment technique. It is is observed to increase with the magnetic field intensity and to slightly decrease with increasing C2H2 percentage in argon. In addition, it decreases with increasing gas pressure. The photodetachment cross section deduced from the photodetachment signal as a function of laser energy is found to be significantly higher than the value expected for the C2H- ion, which may be explained by the presence in the plasma of negatively charged dust particles.

  14. Thin film oxygen partial pressure sensor

    NASA Technical Reports Server (NTRS)

    Wortman, J. J.; Harrison, J. W.; Honbarrier, H. L.; Yen, J.

    1972-01-01

    The development is described of a laboratory model oxygen partial pressure sensor using a sputtered zinc oxide thin film. The film is operated at about 400 C through the use of a miniature silicon bar. Because of the unique resistance versus temperature relation of the silicon bar, control of the operational temperature is achieved by controlling the resistance. A circuit for accomplishing this is described. The response of sputtered zinc oxide films of various thicknesses to oxygen, nitrogen, argon, carbon dioxide, and water vapor caused a change in the film resistance. Over a large range, film conductance varied approximately as the square root of the oxygen partial pressure. The presence of water vapor in the gas stream caused a shift in the film conductance at a given oxygen partial pressure. A theoretical model is presented to explain the characteristic features of the zinc oxide response to oxygen.

  15. DEVICE FOR CONTROL OF OXYGEN PARTIAL PRESSURE

    DOEpatents

    Bradner, H.; Gordon, H.S.

    1957-12-24

    A device is described that can sense changes in oxygen partial pressure and cause a corresponding mechanical displacement sufficient to actuate meters, valves and similar devices. A piston and cylinder arrangement contains a charge of crystalline metal chelate pellets which have the peculiar property of responding to variations in the oxygen content of the ambient atmosphere by undergoing a change in dimension. A lever system amplifies the relative displacement of the piston in the cylinder, and actuates the controlled valving device. This partial pressure oxygen sensing device is useful in controlled chemical reactions or in respiratory devices such as the oxygen demand meters for high altitude aircraft.

  16. Low optical insertion-loss and vacuum-pressure all-fiber acetylene cell based on hollow-core photonic crystal fiber.

    PubMed

    Light, P S; Couny, F; Benabid, F

    2006-09-01

    We report a novel and easy-to-implement hollow-core photonic crystal fiber cell fabrication technique based on helium diffusion through silica. The formed gas cells combine low optical insertion loss (1.8 dB) and vacuum acetylene pressure (microbar regime). The estimates of the final gas pressure, using both Voigt interpolation and electromagnetically induced transparency, show a good match with the initial fitting pressure. PMID:16902611

  17. Partial pressure analysis in space testing

    NASA Technical Reports Server (NTRS)

    Tilford, Charles R.

    1994-01-01

    For vacuum-system or test-article analysis it is often desirable to know the species and partial pressures of the vacuum gases. Residual gas or Partial Pressure Analyzers (PPA's) are commonly used for this purpose. These are mass spectrometer-type instruments, most commonly employing quadrupole filters. These instruments can be extremely useful, but they should be used with caution. Depending on the instrument design, calibration procedures, and conditions of use, measurements made with these instruments can be accurate to within a few percent, or in error by two or more orders of magnitude. Significant sources of error can include relative gas sensitivities that differ from handbook values by an order of magnitude, changes in sensitivity with pressure by as much as two orders of magnitude, changes in sensitivity with time after exposure to chemically active gases, and the dependence of the sensitivity for one gas on the pressures of other gases. However, for most instruments, these errors can be greatly reduced with proper operating procedures and conditions of use. In this paper, data are presented illustrating performance characteristics for different instruments and gases, operating parameters are recommended to minimize some errors, and calibrations procedures are described that can detect and/or correct other errors.

  18. Temperature and pressure dependence of the absolute rate constant for the reactions of NH2 radicals with acetylene and ethylene

    NASA Technical Reports Server (NTRS)

    Bosco, S. R.; Nava, D. F.; Brobst, W. D.; Stief, L. J.

    1984-01-01

    The absolute rate constants for the reaction between the NH2 free radical and acetylene and ethylene is measured experimentally using a flash photolysis technique. The constant is considered to be a function of temperature and pressure. At each temperature level of the experiment, the observed pseudo-first-order rate constants were assumed to be independent of flash intensity. The results of the experiment indicate that the bimolecular rate constant for the NH2 + C2H2 reaction increases with pressure at 373 K and 459 K but not at lower temperatures. Results near the pressure limit conform to an Arrhenius expression of 1.11 (+ or -) 0.36 x 10 to the -13th over the temperature range from 241 to 459 K. For the reaction NH2 + C2H4, a smaller rate of increase in the bimolecular rate constant was observed over the temperature range 250-465 K. The implications of these results for current theoretical models of NH2 + C2H2 (or H4) reactions in the atmospheres of Jupiter and Saturn are discussed.

  19. Thin film devices used as oxygen partial pressure sensors

    NASA Technical Reports Server (NTRS)

    Canady, K. S.; Wortman, J. J.

    1970-01-01

    Electrical conductivity of zinc oxide films to be used in an oxygen partial pressure sensor is measured as a function of temperature, oxygen partial pressure, and other atmospheric constituents. Time response following partial pressure changes is studied as a function of temperature and environmental changes.

  20. Partial pressure measurements with an active spectrometer

    SciTech Connect

    Brooks, N.H.; Jensen, T.H.; Colchin, R.J.; Maingi, R.; Wade, M.R.; Finkenthal, D.F.; Naumenko, N.; Tugarinov, S.

    1998-07-01

    Partial pressure neutral ga measurements have been made using a commercial Penning gauge in conjunction with an active spectrometer. In prior work utilizing bandpass filters and conventional spectrometers, trace concentrations of the hydrogen isotopes H, D, T and of the noble gases He, Ne and Ar were determined from characteristic spectral lines in the light emitted by the neutral species of these elements. For all the elements mentioned, the sensitivity was limited by spectral contamination from a pervasive background of molecular hydrogen radiation. The active spectrometer overcomes this limitations by means of a digital lock-in method and correlation with reference spectra. Preliminary measurements of an admixture containing a trace amount of neon in deuterium show better than a factor of 20 improvement in sensitivity over conventional techniques. This can be further improved by correlating the relative intensities of multiple lines to sets of reference spectra.

  1. [Photodissociation of Acetylene and Acetone using Step-Scan Time-Resolved FTIR Emission Spectroscopy

    NASA Technical Reports Server (NTRS)

    McLaren, Ian A.; Wrobel, Jacek D.

    1997-01-01

    The photodissociation of acetylene and acetone was investigated as a function of added quenching gas pressures using step-scan time-resolved FTIR emission spectroscopy. Its main components consist of Bruker IFS88, step-scan Fourier Transform Infrared (FTIR) spectrometer coupled to a flow cell equipped with Welsh collection optics. Vibrationally excited C2H radicals were produced from the photodissociation of acetylene in the unfocused experiments. The infrared (IR) emission from these excited C2H radicals was investigated as a function of added argon pressure. Argon quenching rate constants for all C2H emission bands are of the order of 10(exp -13)cc/molecule.sec. Quenching of these radicals by acetylene is efficient, with a rate constant in the range of 10(exp -11) cc/molecule.sec. The relative intensity of the different C2H emission bands did not change with the increasing argon or acetylene pressure. However, the overall IR emission intensity decreased, for example, by more than 50% when the argon partial pressure was raised from 0.2 to 2 Torr at fixed precursor pressure of 160mTorr. These observations provide evidence for the formation of a metastable C2H2 species, which are collisionally quenched by argon or acetylene. Problems encountered in the course of the experimental work are also described.

  2. Direct Measurements of the Pressure Coefficient, Partial

    NASA Astrophysics Data System (ADS)

    del Cueto, Joseph Antonio

    1984-06-01

    The pressure coefficient of liquid ('3)He-('4)He mixtures was coupled to directly, with a strain gauge capacitative cell. The cell was filled, pressurized and isolated with a mixture, of ('3)He mole fraction x between 0.50-0.80. The elastic properties of the cell effected a capacitance change in an LC tank circuit driven to oscillation by a Tunnel Diode. The frequency of the circuit, as well as the balance point of an AC Wheatstone circuit sensing a cryo-resistor mounted on the cell, were sampled by a data acquisition(DAS) system, to obtain pressure vs. temperature increments data. The DAS was enabled to perform temperature ramps and cycles with amplitudes of (TURN) (+OR-) 50-100 mK, while concurrently sampling pressure vs. temperature data. It is found that (PAR-DIFF)P/(PAR-DIFF)T)(,v,x) is a piecewise smooth function in the temperature T. For x < x(,t)(P), the data indicate a cusp discontinuity at the lambda temperature of the mixture T(,(lamda))(x,v(p(,(lamda)))), and a simple discontinuity at the onset of phase separation temperature T(,S)(x,v(p(,S))). For x > x(,t)(P), only the phase separation breaks the monotonic behaviour of the pressure coefficient. Where x(,t)(P) is the tricritical concentration at pressure P, referred to in the above. The data for the pressure coefficients are parametrized by smooth functions in appendix 5. This parametrization allows for further thermodynamic analysis, as that of appendix 6, the change in chemical potential difference upon compression. The thermodynamic implications of the measured step in (PAR -DIFF)P/(PAR-DIFF)T)(,v,x), across the onset separation temperature, are explored in appendix 4. The 'volume' minima at the pressures the isochores cross at their pressure minima in temperature, are plotted and analysed to imply that for some concentrations x, the entropy of the mixture is a double valued function of absolute pressure.

  3. Microporous metal–organic framework with dual functionalities for highly efficient removal of acetylene from ethylene/acetylene mixtures

    PubMed Central

    Hu, Tong-Liang; Wang, Hailong; Li, Bin; Krishna, Rajamani; Wu, Hui; Zhou, Wei; Zhao, Yunfeng; Han, Yu; Wang, Xue; Zhu, Weidong; Yao, Zizhu; Xiang, Shengchang; Chen, Banglin

    2015-01-01

    The removal of acetylene from ethylene/acetylene mixtures containing 1% acetylene is a technologically very important, but highly challenging task. Current removal approaches include the partial hydrogenation over a noble metal catalyst and the solvent extraction of cracked olefins, both of which are cost and energy consumptive. Here we report a microporous metal–organic framework in which the suitable pore/cage spaces preferentially take up much more acetylene than ethylene while the functional amine groups on the pore/cage surfaces further enforce their interactions with acetylene molecules, leading to its superior performance for this separation. The single X-ray diffraction studies, temperature dependent gas sorption isotherms, simulated and experimental column breakthrough curves and molecular simulation studies collaboratively support the claim, underlying the potential of this material for the industrial usage of the removal of acetylene from ethylene/acetylene mixtures containing 1% acetylene at room temperature through the cost- and energy-efficient adsorption separation process. PMID:26041691

  4. Development of pressurized coal partial combustor

    SciTech Connect

    Yoshida, K.; Ino, T.; Yamamoto, T.; Kimura, N.

    1995-12-31

    The integrated gasification combined cycle (IGCC), an environment-friendly power generation system of high thermal efficiency, is being developed via various approaches around the world. The oxygen-blown entrained flow gasification process is a relatively simple method of producing medium calorie coal gas suitable for application to gas turbines. Various systems for this process have been developed to a demonstration level in Europe and America. Japan has actively been developing the air-blown process. However, taking stable molten slag discharge into consideration, coal must be supplied at two stages to raise the combustor temperature in ash molten part. Only two reports have been presented regarding two-stage coal supply. One is the report on an experiment with the Hycol gasifier, in which air feed ratio is varied, with coal feed fixed. The other is report on a simulation study with various gasifier coal feed ratios, conducted at Central Research Institute of Electric Power Industry. It seems that the appropriate feed ratio has not yet been established. Through this activity, a unique furnace construction has been established, and these influences of stoichiometric air ratio, of oxygen enrichment, of char recycling and of coal types on performance have been clarified. The purpose of the present study is to apply this developed CPC techniques to a Pressurized CPC (PCPC), thereby improving the IGCC technology. For the present study, we conducted systematic experiments on the air-blown process with a two stage dry feed system, using a 7 t/d-coal bench scale PCPC test facility, operated at the pressure of 0.4 MPa, and clarified the influence of coal feed ratio on coal gasification performance. This report describes the above-mentioned bench scale test procedures and results, and also some informations about a plan of a 25 t/d-coal pilot test system.

  5. A mid-infrared absorption diagnostic for acetylene detection

    NASA Astrophysics Data System (ADS)

    KC, Utsav; Nasir, Ehson F.; Farooq, Aamir

    2015-08-01

    Acetylene is an important combustion intermediate and plays a critical role in soot formation. Accurate measurements of trace concentrations of acetylene can be very useful in validating hydrocarbon oxidation and soot formation mechanisms. Strongest vibrational band of acetylene near 13.7 μm is probed here to develop a highly sensitive absorption diagnostic. Experiments are carried out behind reflected shock waves to measure absorption cross sections of acetylene near 730 cm-1 over a wide range of temperatures (1000-2200 K) and pressures (1-5 bar). The diagnostic is demonstrated by measuring acetylene formation during the shock-heated pyrolysis and oxidation of propene.

  6. Properties of acetylene

    SciTech Connect

    Pavlovcak, J.T.

    1994-12-31

    Acetylene continues to be the most widely used fuel in the oxyfuel cutting and welding industry. It displays properties that enhance its benefits to the industry, but at the same time, present potential hazards that have to be addressed. The presentation explores the main properties or characteristics of acetylene -- odor, toxicity, flammability, composition, and manufacture. it expands on those properties that are unique to acetylene and which account for its main value to the user or which constitute the chief concern for safe use of acetylene. The presentation explains characteristics such as anosmia, flammable or explosive range, ignition energy, autoignition temperature, and flame temperature, comparing these values for acetylene to other common gaseous fuels. it explains the unique property of acetylene to decompose explosively in the absence of air or oxygen. The toxicological aspects of acetylene is discussed, including anesthetic effect and simple asphyxiant, showing the increasing severity of symptoms to increasing levels of oxygen deficiency. The main value of this basic review of the properties of acetylene is to remind people of the benefits of acetylene due to its unique properties, and to realert them to the potential hazards that also have to be addressed to control the properties of acetylene.

  7. Report on ISS Oxygen Production, Resupply, and Partial Pressure Management

    NASA Technical Reports Server (NTRS)

    Schaezler, Ryan; Ghariani, Ahmed; Leonard, Daniel; Lehman, Daniel

    2011-01-01

    The majority of oxygen used on International Space Station (ISS) is for metabolic support and denitrogenation procedures prior to Extra-Vehicular Activities. Oxygen is supplied by various visiting vehicles such as the Progress and Shuttle in addition to oxygen production capability on both the United States On-Orbit Segment (USOS) and Russian Segment (RS). To maintain a habitable atmosphere the oxygen partial pressure is controlled between upper and lower bounds. The full range of the allowable oxygen partial pressure along with the increased ISS cabin volume is utilized as a buffer allowing days to pass between oxygen production or direct addition of oxygen to the atmosphere from reserves. This paper summarizes amount of oxygen supplied and produced from all of the sources and describes past experience of managing oxygen partial pressure along with the range of management options available to the ISS.

  8. Measurement of partial pressures in vacuum technology and vacuum physics

    NASA Technical Reports Server (NTRS)

    Huber, W. K.

    1986-01-01

    It is pointed out that the measurement of gaseous pressures of less than 0.0001 torr is based on the ionization of gas atoms and molecules due to collisions with electrons. The particle density is determined in place of the pressure. The ionization cross sections for molecules of various gases are discussed. It is found that the true pressure in a vacuum system cannot be determined with certainty if it is unknown which gas is present. Effects of partial pressure determination on the condition of the vacuum system are discussed together with ion sources, systems of separation, and ion detection.

  9. A System for Incubations at High Gas Partial Pressure

    PubMed Central

    Sauer, Patrick; Glombitza, Clemens; Kallmeyer, Jens

    2012-01-01

    High-pressure is a key feature of deep subsurface environments. High partial pressure of dissolved gasses plays an important role in microbial metabolism, because thermodynamic feasibility of many reactions depends on the concentration of reactants. For gases, this is controlled by their partial pressure, which can exceed 1 MPa at in situ conditions. Therefore, high hydrostatic pressure alone is not sufficient to recreate true deep subsurface in situ conditions, but the partial pressure of dissolved gasses has to be controlled as well. We developed an incubation system that allows for incubations at hydrostatic pressure up to 60 MPa, temperatures up to 120°C, and at high gas partial pressure. The composition and partial pressure of gasses can be manipulated during the experiment. To keep costs low, the system is mainly made from off-the-shelf components with only very few custom-made parts. A flexible and inert PVDF (polyvinylidene fluoride) incubator sleeve, which is almost impermeable for gases, holds the sample and separates it from the pressure fluid. The flexibility of the incubator sleeve allows for sub-sampling of the medium without loss of pressure. Experiments can be run in both static and flow-through mode. The incubation system described here is usable for versatile purposes, not only the incubation of microorganisms and determination of growth rates, but also for chemical degradation or extraction experiments under high gas saturation, e.g., fluid–gas–rock-interactions in relation to carbon dioxide sequestration. As an application of the system we extracted organic compounds from sub-bituminous coal using H2O as well as a H2O–CO2 mixture at elevated temperature (90°C) and pressure (5 MPa). Subsamples were taken at different time points during the incubation and analyzed by ion chromatography. Furthermore we demonstrated the applicability of the system for studies of microbial activity, using samples from the Isis mud volcano. We could

  10. A system for incubations at high gas partial pressure.

    PubMed

    Sauer, Patrick; Glombitza, Clemens; Kallmeyer, Jens

    2012-01-01

    High-pressure is a key feature of deep subsurface environments. High partial pressure of dissolved gasses plays an important role in microbial metabolism, because thermodynamic feasibility of many reactions depends on the concentration of reactants. For gases, this is controlled by their partial pressure, which can exceed 1 MPa at in situ conditions. Therefore, high hydrostatic pressure alone is not sufficient to recreate true deep subsurface in situ conditions, but the partial pressure of dissolved gasses has to be controlled as well. We developed an incubation system that allows for incubations at hydrostatic pressure up to 60 MPa, temperatures up to 120°C, and at high gas partial pressure. The composition and partial pressure of gasses can be manipulated during the experiment. To keep costs low, the system is mainly made from off-the-shelf components with only very few custom-made parts. A flexible and inert PVDF (polyvinylidene fluoride) incubator sleeve, which is almost impermeable for gases, holds the sample and separates it from the pressure fluid. The flexibility of the incubator sleeve allows for sub-sampling of the medium without loss of pressure. Experiments can be run in both static and flow-through mode. The incubation system described here is usable for versatile purposes, not only the incubation of microorganisms and determination of growth rates, but also for chemical degradation or extraction experiments under high gas saturation, e.g., fluid-gas-rock-interactions in relation to carbon dioxide sequestration. As an application of the system we extracted organic compounds from sub-bituminous coal using H(2)O as well as a H(2)O-CO(2) mixture at elevated temperature (90°C) and pressure (5 MPa). Subsamples were taken at different time points during the incubation and analyzed by ion chromatography. Furthermore we demonstrated the applicability of the system for studies of microbial activity, using samples from the Isis mud volcano. We could

  11. EQUILIBRIUM PARTIAL PRESSURE OF SULFUR DIOXIDE IN ALKALINE SCRUBBING PROCESSES

    EPA Science Inventory

    The report gives results of IERL-RTP in-house studies in which equilibrium partial pressure of SO2 was measured as a function of pH, temperature, and concentration of sulfur (IV) on various scrubber liquors. These studies were done for potassium-, sodium-, and citrate-based scrub...

  12. Calibration Of Partial-Pressure-Of-Oxygen Sensors

    NASA Technical Reports Server (NTRS)

    Yount, David W.; Heronimus, Kevin

    1995-01-01

    Report and analysis of, and discussion of improvements in, procedure for calibrating partial-pressure-of-oxygen sensors to satisfy Spacelab calibration requirements released. Sensors exhibit fast drift, which results in short calibration period not suitable for Spacelab. By assessing complete process of determining total drift range available, calibration procedure modified to eliminate errors and still satisfy requirements without compromising integrity of system.

  13. Using Dalton's Law of Partial Pressures to Determine the Vapor Pressure of a Volatile Liquid

    ERIC Educational Resources Information Center

    Hilgeman, Fred R.; Bertrand, Gary; Wilson, Brent

    2007-01-01

    This experiment, designed for a general chemistry laboratory, illustrates the use of Dalton's law of partial pressures to determine the vapor pressure of a volatile liquid. A predetermined volume of air is injected into a calibrated tube filled with a liquid whose vapor pressure is to be measured. The volume of the liquid displaced is greater than…

  14. Acetylenic carbon allotrope

    SciTech Connect

    1999-11-16

    A fourth allotrope of carbon, an acetylenic carbon allotrope, is described. The acetylenic carbon allotropes of the present invention are more soluble than the other known carbon allotropes in many common organic solvents and possesses other desirable characteristics, e.g. high electron density, ability to burn cleanly, and electrical conductive properties. Many uses for this fourth allotrope are described herein.

  15. Acetylenic carbon allotrope

    DOEpatents

    Lagow, Richard J.

    1999-01-01

    A fourth allotrope of carbon, an acetylenic carbon allotrope, is described. The acetylenic carbon allotropes of the present invention are more soluble than the other known carbon allotropes in many common organic solvents and possesses other desirable characteristics, e.g. high electron density, ability to burn cleanly, and electrical conductive properties. Many uses for this fourth allotrope are described herein.

  16. Acetylenic carbon allotrope

    DOEpatents

    Lagow, Richard J.

    1998-01-01

    A fourth allotrope of carbon, an acetylenic carbon allotrope, is described. The acetylenic carbon allotropes of the present invention are more soluble than the other known carbon allotropes in many common organic solvents and possesses other desirable characteristics, e.g. high electron density, ability to burn cleanly, and electrical conductive properties. Many uses for this fourth allotrope are described herein.

  17. Acetylenic carbon allotrope

    DOEpatents

    Lagow, R.J.

    1998-02-10

    A fourth allotrope of carbon, an acetylenic carbon allotrope, is described. The acetylenic carbon allotropes of the present invention are more soluble than the other known carbon allotropes in many common organic solvents and possesses other desirable characteristics, e.g. high electron density, ability to burn cleanly, and electrical conductive properties. Many uses for this fourth allotrope are described herein. 17 figs.

  18. Reduced atmospheric pressure in Radish: Alteration of NCER and transpiration at decreased oxygen partial pressures

    NASA Astrophysics Data System (ADS)

    Wehkamp, Cara Ann; Stasiak, Michael; Wheeler, Raymond; Dixon, Mike

    Fundamental to the future of space exploration is the development of advanced life support systems capable of maintaining crews for significant periods without re-supply from Earth. Significant research is focused on the development of bioregenerative life support systems to be used in conjunction with the current physico-chemical methods. These bioregenerative life support systems harness natural ecosystem processes and employ plant photosynthesis and transpiration to produce food, oxygen and regenerate water while consuming carbon dioxide. The forthcoming exploration of the Moon and Mars has prompted interest into the effects of hypobaria on plant development. Reduced atmospheric pressures will lessen the pressure gradient between the structure and the local environment thereby decreasing gas leakage and possibly the structural mass of the plant growth facility. In order to establish the optimal specifications for reduced pressure plant growth structures it is essential to determine the atmospheric pressure limits required for conventional plant development and growth. Due to its physiological importance, oxygen will compose a significant portion of these minimal environments. The objective of this study was to test the hypothesis that reduced atmospheric pressure and decreased oxygen partial pressures had no effect on radish productivity. Radishes (Raphanus sativa L. cv. Cherry Bomb II) were grown from seed in the University of Guelph's Hypobaric Plant Growth Chambers for a period of 21 days. Treatments included total pressures of 10, 33, 66 and 96 kPa and oxygen partial pressures of 2, 7, 14 and 20 kPa. Experiments demonstrated that reduced partial pressures of oxygen had a greater effect on radish growth than hypobaria. Results showed a reduction in net carbon exchange rate and transpiration with decreasing oxygen partial pressures leading to diminished productivity. Keywords: hypobaric, radish, oxygen partial pressure, variable pressure chamber

  19. Estimation of partial pressure during graphite conditioning by matrix method

    NASA Astrophysics Data System (ADS)

    Chaudhuri, P.; Prakash, A.; Reddy, D. C.

    2008-05-01

    Plasma Facing Components (PFC) of SST-1 tokamak are designed to be compatible for UHV as it is kept in the main vacuum vessel. Graphite is the most widely used plasma facing material in present day tokamaks. High thermal shock resistance and low atomic number carbon are the most important properties of graphite for this application. However, graphite is porous and absorbs gases, which may be released during plasma operation. Graphite tiles are baked at high temperature of about 1000 °C in high vacuum (10-5 Torr) for several hours before installing them in the tokamak to remove the impurities (mainly water vapour and metal impurities), which may have been deposited during machining of the tiles‥ The measurements of the released gas (such as H2, H2O, CO, CO2, Hydrocarbons, etc.) from graphite tiles during baking are accomplished with the help of a Quadrupole Mass Analyzer (QMA). Since, the output of this measurement is a mass spectrum and not the partial pressures of the residual gases, one needs to adopt some procedure to convert the spectrum to obtain the partial pressures. The conventional method of analysis is tedious and time consuming. We propose a new approach based on constructing a set of linear equations and solving them using matrix operations. This is a simple method compared to the conventional one and also eliminates the limitations of the conventional method. A Fortran program has been developed which identifies the likely gases present in the vacuum system and calculates their partial pressures from the data of the residual gas analyzers. Application of this method of calculating partial pressures from mass spectra data will be discussed in detail in this paper.

  20. Oxygen-Partial-Pressure Sensor for Aircraft Oxygen Mask

    NASA Technical Reports Server (NTRS)

    Kelly, Mark; Pettit, Donald

    2003-01-01

    A device that generates an alarm when the partial pressure of oxygen decreases to less than a preset level has been developed to help prevent hypoxia in a pilot or other crewmember of a military or other high-performance aircraft. Loss of oxygen partial pressure can be caused by poor fit of the mask or failure of a hose or other component of an oxygen distribution system. The deleterious physical and mental effects of hypoxia cause the loss of a military aircraft and crew every few years. The device is installed in the crewmember s oxygen mask and is powered via communication wiring already present in all such oxygen masks. The device (see figure) includes an electrochemical sensor, the output potential of which is proportional to the partial pressure of oxygen. The output of the sensor is amplified and fed to the input of a comparator circuit. A reference potential that corresponds to the amplified sensor output at the alarm oxygen-partial-pressure level is fed to the second input of the comparator. When the sensed partial pressure of oxygen falls below the minimum acceptable level, the output of the comparator goes from the low state (a few millivolts) to the high state (near the supply potential, which is typically 6.8 V for microphone power). The switching of the comparator output to the high state triggers a tactile alarm in the form of a vibration in the mask, generated by a small 1.3-Vdc pager motor spinning an eccentric mass at a rate between 8,000 and 10,000 rpm. The sensation of the mask vibrating against the crewmember s nose is very effective at alerting the crewmember, who may already be groggy from hypoxia and is immersed in an environment that is saturated with visual cues and sounds. Indeed, the sensation is one of rudeness, but such rudeness could be what is needed to stimulate the crewmember to take corrective action in a life-threatening situation.

  1. High-Pressure Equation of State for Partially Ionic Solids

    NASA Technical Reports Server (NTRS)

    Schlosser, Herbert; Ferrante, John

    1993-01-01

    Recently, we showed that the cohesive energy of partially ionic solids may be characterized by a two-term energy relationship consisting of a Coulomb term arising from the valence-charge transfer delta Z between the atoms, and a scaled universal energy function E(sup *)(a(sup *)), which accounts for the partially covalent character of the bond and for the repulsion between the atomic cores for small R; a(sup *) is a scaled length. Normalized cohesive-energy curves of alkali halide crystals and of Ti and Ag halide crystals were obtained, and the cohesive-energy-curve parameters were used to generate theoretical equation-of-state (EOS) curves for the Li, Na, K, Cs, and Ag halides. Good agreement was obtained with the experimental isothermal compression curves over a wide pressure range (0-90 kbar). In this paper we verify that the cohesive-energy relationship is valid for divalent partially ionic solids; physically reasonable charge-transfer values (1.80 less than delta Z less than 2.0) are obtained for MgO, CaO, and CaS. Next, EOS curves for LiF, NaF, Nal, CsCl, Csl, MgO, CaO, and CaS are generated in terms of the cohesive-energy parameters. These EOS's yield excellent fits to experimental isothermal-compression data and to shock-wave data to very high pressures (P(sub max)= 250-1350 kbar).

  2. Determination of the partial pressure of thallium in high-pressure lamp arcs: A comparative study

    SciTech Connect

    Karabourniotis, D.; Couris, S.; Damelincourt, J.J.; Aubes, M.

    1986-08-01

    The partial pressure of thallium in high-pressure Hg-TlI discharges with different mercury, thallium, and electron pressures has been measured by using the optically thin line Tl 655 nm and the self-reversed line Tl 535 nm. The partial pressure of the arc axis has been measured from the line Tl 655nm. The effective partial pressure has been measured from the self-reversed line Tl 535 nm on the basis of the multiparameter method, and it has been calculated from the known axis pressure of thallium and the calculation of its radial variation by taking into account the chemical reactions. The experimental results confirm the dispersion character of the blue wing of the line Tl 535 nm. The systematic difference obtained between the measured and calculated effective pressure, particularly at the moment of minimum electron density, may be interpreted by deviations from the local thermodynamic equilibrium (LTE) caused by overpopulation of the upper level of the line Tl 535 nm.

  3. Oxygen partial pressure measurement in the HVOF gun tail flame

    SciTech Connect

    Korpiola, K.; Hirvonen, J.P.; Jalkanen, H.; Laas, L.; Rossi, F.

    1995-12-31

    An important aspect of the HVOF thermal spray process is the turbulent mixing of the spray jet with the surrounding air. The air mixing into the jet causes undesirable oxidation of the sprayed coating. In this paper a low cost and accurate method to determine the degree of air mixing is presented. This method was used to measure for the first time the partial pressure of oxygen in the thermal spray flame. The measuring method is based on electrochemical determination of oxygen potential in the tail flame using a solid electrolyte cell. The oxygen partial pressure in the HVOF-gun tail flame was measured with the fuel-to-oxygen ratio, the fuel flow rate and the stand-off distance as variables. The oxygen content of the tail flame was measured and found to vary between 4 to 17% depending on fuel to oxygen ratios and stand-off distances. Such high oxygen contents are several magnitudes too high if serious oxidation in the coating is to be avoided.

  4. DEVELOPMENT OF PRESSURIZED CIRCULATING FLUIDIZED BED PARTIAL GASIFICATION MODULE (PGM)

    SciTech Connect

    Archie Robertson

    2003-10-29

    Foster Wheeler Power Group, Inc. is working under US Department of Energy contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% and produce near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines, or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The amount of syngas and char produced by the PGM can be tailored to fit the production objectives of the overall plant, i.e., power generation, clean liquid fuel production, chemicals production, etc. Hence, PGM is a robust building bock that offers all the advantages of coal gasification but in a more user-friendly form; it is also fuel flexible in that it can use alternative fuels such as biomass, sewerage sludge, etc. This report describes the work performed during the July 1--September 30, 2003 time period.

  5. DEVELOPMENT OF PRESSURIZED CIRCULATING FLUIDIZED BED PARTIAL GASIFICATION MODULE (PGM)

    SciTech Connect

    Archie Robertson

    2003-07-23

    Foster Wheeler Power Group, Inc. is working under US Department of Energy contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% and produce near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines, or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The amount of syngas and char produced by the PGM can be tailored to fit the production objectives of the overall plant, i.e., power generation, clean liquid fuel production, chemicals production, etc. Hence, PGM is a robust building bock that offers all the advantages of coal gasification but in a more user-friendly form; it is also fuel flexible in that it can use alternative fuels such as biomass, sewerage sludge, etc. This report describes the work performed during the April 1--June 30, 2003 time period.

  6. Development of Pressurized Circulating Fluidized Bed Partial Gasification Module (PGM)

    SciTech Connect

    A. Robertson

    2002-09-30

    Foster Wheeler Power Group, Inc. is working under US Department of Energy contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% and produce near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines, or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The amount of syngas and char produced by the PGM can be tailored to fit the production objectives of the overall plant, i.e., power generation, clean liquid fuel production, chemicals production, etc. Hence, PGM is a robust building bock that offers all the advantages of coal gasification but in a more user-friendly form; it is also fuel flexible in that it can use alternative fuels such as biomass, sewerage sludge, etc. This report describes the work performed during the July 1-September 30, 2002 time period.

  7. DEVELOPMENT OF PRESSURIZED CIRCULATING FLUDIZED BED PARTIAL GASIFICATION MODULE (PGM)

    SciTech Connect

    Archie Robertson

    2002-07-10

    Foster Wheeler Power Group, Inc. is working under US Department of Energy contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% and produce near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines, or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The amount of syngas and char produced by the PGM can be tailored to fit the production objectives of the overall plant, i.e., power generation, clean liquid fuel production, chemicals production, etc. Hence, PGM is a robust building bock that offers all the advantages of coal gasification but in a more user-friendly form; it is also fuel flexible in that it can use alternative fuels such as biomass, sewerage sludge, etc. This report describes the work performed during the April 1--June 30, 2002 time period.

  8. Development of Pressurized Circulating Fluidized Bed Partial Gasification Module (PGM)

    SciTech Connect

    A. Robertson

    2003-12-31

    Foster Wheeler Power Group, Inc. is working under US Department of Energy contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% and produce near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines, or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The amount of syngas and char produced by the PGM can be tailored to fit the production objectives of the overall plant, i.e., power generation, clean liquid fuel production, chemicals production, etc. Hence, PGM is a robust building bock that offers all the advantages of coal gasification but in a more user-friendly form; it is also fuel flexible in that it can use alternative fuels such as biomass, sewerage sludge, etc. This report describes the work performed during the October 1 - December 31, 2003 time period.

  9. DEVELOPMENT OF PRESSURIZED CIRCULATING FLUIDIZED BED PARTIAL GASIFICATION MODULE (PGM)

    SciTech Connect

    Unknown

    2003-01-30

    Foster Wheeler Power Group, Inc. is working under US Department of Energy contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% and produce near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines, or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The amount of syngas and char produced by the PGM can be tailored to fit the production objectives of the overall plant, i.e., power generation, clean liquid fuel production, chemicals production, etc. Hence, PGM is a robust building bock that offers all the advantages of coal gasification but in a more user-friendly form; it is also fuel flexible in that it can use alternative fuels such as biomass, sewerage sludge, etc. This report describes the work performed during the October 1--December 31, 2002 time period.

  10. Fine-tuning control on CNT diameter distribution, length and density using thermal CVD growth at atmospheric pressure: an in-depth analysis on the role of flow rate and flow duration of acetylene (C2H2) gas

    NASA Astrophysics Data System (ADS)

    Tripathi, Nishant; Mishra, Prabhash; Harsh, Harsh; Islam, S. S.

    2015-01-01

    An optimization control has been demonstrated to obtain carbon nanotubes having specific diameter distribution, length, homogeneity, and yield during its growth by thermal chemical vapor deposition technique under atmospheric pressure. Carbon nanotubes (CNTs) were grown on silicon wafer where a predeposition of iron catalyst of 2 nm thickness was made by sputtering. The growth was conducted under two variable parameters, i.e., flow rate and flow duration. Argon and hydrogen mixture was used for pretreatment of catalyst and as etching gas, and acetylene as a carbon precursor. In-depth analysis shows that increase in flow rate from 10 to 50 sccm resulted in increase in the concentration of amorphous carbon, CNTs diameter range and decrease in length, we found best result at 20 sccm flow rate of acetylene gas. On the other hand, as we varied flow duration from 6 to 14 min, with keeping flow rate of acetylene 20 sccm constant, dense homogeneous growth of horizontal CNTs network plus an increase in length and diameter range were observed. An optimization of flow rate and flow duration is presented here to obtain a selective diameter distribution and length as expected by this growth technique. Atomic force microscopy, field emission scanning electron microscopy and Raman spectroscopy were used to investigate the samples' morphologies in support of the observations made.

  11. 21 CFR 868.1200 - Indwelling blood oxygen partial pressure (PO2) analyzer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Indwelling blood oxygen partial pressure (PO2... Indwelling blood oxygen partial pressure (PO2) analyzer. (a) Identification. An indwelling blood oxygen... electrode) and that is used to measure, in vivo, the partial pressure of oxygen in blood to aid...

  12. 21 CFR 868.1200 - Indwelling blood oxygen partial pressure (PO2) analyzer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Indwelling blood oxygen partial pressure (PO2... Indwelling blood oxygen partial pressure (PO2) analyzer. (a) Identification. An indwelling blood oxygen... electrode) and that is used to measure, in vivo, the partial pressure of oxygen in blood to aid...

  13. 21 CFR 868.1200 - Indwelling blood oxygen partial pressure (PO2) analyzer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Indwelling blood oxygen partial pressure (PO2... Indwelling blood oxygen partial pressure (PO2) analyzer. (a) Identification. An indwelling blood oxygen... electrode) and that is used to measure, in vivo, the partial pressure of oxygen in blood to aid...

  14. 21 CFR 868.1200 - Indwelling blood oxygen partial pressure (PO2) analyzer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Indwelling blood oxygen partial pressure (PO2... Indwelling blood oxygen partial pressure (PO2) analyzer. (a) Identification. An indwelling blood oxygen... electrode) and that is used to measure, in vivo, the partial pressure of oxygen in blood to aid...

  15. 21 CFR 868.1200 - Indwelling blood oxygen partial pressure (PO2) analyzer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Indwelling blood oxygen partial pressure (PO2... Indwelling blood oxygen partial pressure (PO2) analyzer. (a) Identification. An indwelling blood oxygen... electrode) and that is used to measure, in vivo, the partial pressure of oxygen in blood to aid...

  16. 21 CFR 868.1150 - Indwelling blood carbon dioxide partial pressure (PCO2) analyzer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Indwelling blood carbon dioxide partial pressure....1150 Indwelling blood carbon dioxide partial pressure (PCO2) analyzer. (a) Identification. An indwelling blood carbon dioxide partial pressure PCO2 analyzer is a device that consists of a...

  17. 21 CFR 868.1150 - Indwelling blood carbon dioxide partial pressure (PCO2) analyzer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Indwelling blood carbon dioxide partial pressure....1150 Indwelling blood carbon dioxide partial pressure (PCO2) analyzer. (a) Identification. An indwelling blood carbon dioxide partial pressure PCO2 analyzer is a device that consists of a...

  18. 21 CFR 868.1150 - Indwelling blood carbon dioxide partial pressure (PCO2) analyzer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Indwelling blood carbon dioxide partial pressure....1150 Indwelling blood carbon dioxide partial pressure (PCO2) analyzer. (a) Identification. An indwelling blood carbon dioxide partial pressure PCO2 analyzer is a device that consists of a...

  19. 21 CFR 868.1150 - Indwelling blood carbon dioxide partial pressure (PCO2) analyzer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Indwelling blood carbon dioxide partial pressure....1150 Indwelling blood carbon dioxide partial pressure (PCO2) analyzer. (a) Identification. An indwelling blood carbon dioxide partial pressure PCO2 analyzer is a device that consists of a...

  20. 21 CFR 868.1150 - Indwelling blood carbon dioxide partial pressure (PCO2) analyzer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Indwelling blood carbon dioxide partial pressure....1150 Indwelling blood carbon dioxide partial pressure (PCO2) analyzer. (a) Identification. An indwelling blood carbon dioxide partial pressure PCO2 analyzer is a device that consists of a...

  1. DEVELOPMENT OF PRESSURIZED CIRCULATING FLUIDIZED BED PARTIAL GASIFICATION MODULE (PGM)

    SciTech Connect

    Unknown

    2002-03-29

    Foster Wheeler Development Corporation is working under DOE contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% while producing near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The unique aspect of the process is that it utilizes a pressurized circulating fluidized bed partial gasifier and does not attempt to consume the coal in a single step. To convert all the coal to syngas in a single step requires extremely high temperatures ({approx}2500 to 2800 F) that melt and vaporize the coal and essentially drive all coal ash contaminants into the syngas. Since these contaminants can be corrosive to power generating equipment, the syngas must be cooled to near room temperature to enable a series of chemical processes to clean the syngas. Foster Wheeler's process operates at much lower temperatures that control/minimize the release of contaminants; this eliminates/minimizes the need for the expensive, complicated syngas heat exchangers and chemical cleanup systems typical of high temperature gasification. By performing the gasification in a circulating bed, a significant amount of syngas can still be produced despite the reduced temperature and the circulating bed allows easy scale up to large size plants. Rather than air, it can also operate with oxygen to facilitate

  2. DEVELOPMENT OF PRESSURIZED CIRCULATING FLUIDIZED BED PARTIAL GASIFICATION MODULE (PGM)

    SciTech Connect

    Archie Robertson

    2004-07-01

    Foster Wheeler Power Group, Inc. is working under US Department of Energy Contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% and produce near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines, or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The amount of syngas and char produced by the PGM can be tailored to fit the production objectives of the overall plant, i.e., power generation, clean liquid fuel production, chemicals production, etc. Hence, PGM is a robust building bock that offers all the advantages of coal gasification but in a more user-friendly form; it is also fuel flexible in that it can use alternative fuels such as biomass, sewerage sludge, etc. Under this contract a series of pilot plant tests are being conducted to ascertain PGM performance with a variety of fuels. The performance and economics of a PGM based plant designed for the co-production of hydrogen and electricity will also be determined. This report describes the work performed during the April-June 30, 2004 time period.

  3. Acylamidation of acetylenes

    SciTech Connect

    Gridnev, I.D.; Balenkova, E.S.

    1989-01-10

    The reactions of phenylacetylene, 1-heptyne, and diphenylacetylene with the complexes of acetylfluoroborate with acetonitrile and with chloroacetonitrile take place regiospecifically and stereospecifically as syn-addition of the acetyl group and nitrile at the triple bond of the acetylene and lead to previously unknown Z-N-acyl-/beta/-amino, /alpha/,/beta/-unsaturated ketones.

  4. Acetylene terminated matrix resins

    NASA Technical Reports Server (NTRS)

    Goldfarb, I. J.; Lee, Y. C.; Arnold, F. E.; Helminiak, T. E.

    1985-01-01

    The synthesis of resins with terminal acetylene groups has provided a promising technology to yield high performance structural materials. Because these resins cure through an addition reaction, no volatile by-products are produced during the processing. The cured products have high thermal stability and good properties retention after exposure to humidity. Resins with a wide variety of different chemical structures between the terminal acetylene groups are synthesized and their mechanical properties studied. The ability of the acetylene cured polymers to give good mechanical properties is demonstrated by the resins with quinoxaline structures. Processibility of these resins can be manipulated by varying the chain length between the acetylene groups or by blending in different amounts of reactive deluents. Processing conditions similar to the state-of-the-art epoxy can be attained by using backbone structures like ether-sulfone or bis-phenol-A. The wide range of mechanical properties and processing conditions attainable by this class of resins should allow them to be used in a wide variety of applications.

  5. DEVELOPMENT OF PRESSURIZED CIRCULATING FLUIDIZED BED PARTIAL GASIFICATION MODULE (PGM)

    SciTech Connect

    Unknown

    2001-07-10

    Foster Wheeler Development Corporation is working under DOE contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% while producing near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The unique aspect of the process is that it utilizes a pressurized circulating fluidized bed partial gasifier and does not attempt to consume the coal in a single step. To convert all the coal to syngas in a single step requires extremely high temperatures ({approx}2500 to 2800F) that melt and vaporize the coal and essentially drive all coal ash contaminants into the syngas. Since these contaminants can be corrosive to power generating equipment, the syngas must be cooled to near room temperature to enable a series of chemical processes to clean the syngas. Foster Wheeler's process operates at much lower temperatures that control/minimize the release of contaminants; this eliminates/minimizes the need for the expensive, complicated syngas heat exchangers and chemical cleanup systems typical of high temperature gasification. By performing the gasification in a circulating bed, a significant amount of syngas can still be produced despite the reduced temperature and the circulating bed allows easy scale up to large size plants. Rather than air, it can also operate with oxygen to facilitate

  6. Numerical analysis of the effect of acetylene and benzene addition to low-pressure benzene-rich flat flames on polycyclic aromatic hydrocarbon formation

    SciTech Connect

    Kunioshi, Nilson; Komori, Seisaku; Fukutani, Seishiro

    2006-10-15

    A modification of the CHEMKIN II package has been proposed for modeling addition of an arbitrary species at an arbitrary temperature to an arbitrary distance from the burner along a flat flame. The modified program was applied to the problem of addition of acetylene or benzene to different positions of a 40-Torr, {phi}=2.4 benzene/O{sub 2}/40%-N{sub 2} premixed flame to reach final equivalence ratios of {phi}=2.5 and 2.681. The results obtained showed that acetylene addition to early positions of the flame led to significant increase in pyrene production rates, but pyrene concentrations were lower in the flames with acetylene addition in both the {phi}=2.5 and 2.681 cases. Addition of benzene to the flame did not alter pyrene production rates in either the {phi}=2.5 or 2.681 cases; however, for {phi}=2.5, pyrene concentrations increased with benzene addition, while for {phi}=2.681, pyrene contents decreased in comparison to the correspondent flames with no addition. Acetylene addition led to a significant increase in pyrene production rates, but the pyrene levels dropped due to increase in the flow velocity. Pyrene production rates were not sensitive to benzene addition, but pyrene contents increased with benzene addition when the flow velocity decreased. These results show that PAH concentration changes accompanying species addition to flames should be interpreted carefully, because an increase or decrease in the content of a PAH species does not necessarily reflect an effect on its formation rate or mechanism. (author)

  7. Measurements of Surface Ocean Carbon Dioxide Partial Pressure During WOCE

    SciTech Connect

    Weiss, R.F.

    1998-10-15

    All of the technical goals of the World Ocean Circulation Experiment (WOCE) field program which were supported under the Department of Energy research grant ''Measurements of Surface Ocean Carbon Dioxide Partial Pressure During WOCE'' (DE-FG03-90ER60981) have been met. This has included the measurement of the partial pressures of carbon dioxide (C0{sub 2}) and nitrous oxide (N{sub 2}O) in both the surface ocean and the atmosphere on 24 separate shipboard expedition legs of the WOCE Hydrographic Programme. These measurements were made in the Pacific, Indian and Atlantic Oceans over a six-and-a-half year period, and over a distance of nearly 200,000 kilometers of ship track. The total number of measurements, including ocean measurements, air measurements and standard gas measurements, is about 136,000 for each gas, or about 34,000 measurements of each gas in the ocean and in the air. This global survey effort is directed at obtaining a better understanding of the role of the oceans in the global atmospheric budgets of two important natural and anthropogenic modulators of climate through the ''greenhouse effect'', CO{sub 2} and N{sub 2}O, and an important natural and anthropogenic modulator of the Earth's protective ozone layer through catalytic processes in the stratosphere, N{sub 2}O. For both of these compounds, the oceans play a major role in their global budgets. In the case of CO{sub 2}, roughly half of the anthropogenic production through the combustion of fossil fuels has been absorbed by the world's oceans. In the case of N{sub 2}O, roughly a third of the natural flux to the atmosphere originates in the oceans. As the interpretation of the variability in the oceanic distributions of these compounds improves, measurements such as those supported by this research project are playing an increasingly important role in improving our understanding of natural and anthropogenic influences on climate and ozone. (B204)

  8. Factors associated with blood oxygen partial pressure and carbon dioxide partial pressure regulation during respiratory extracorporeal membrane oxygenation support: data from a swine model

    PubMed Central

    Park, Marcelo; Mendes, Pedro Vitale; Costa, Eduardo Leite Vieira; Barbosa, Edzangela Vasconcelos Santos; Hirota, Adriana Sayuri; Azevedo, Luciano Cesar Pontes

    2016-01-01

    Objective The aim of this study was to explore the factors associated with blood oxygen partial pressure and carbon dioxide partial pressure. Methods The factors associated with oxygen - and carbon dioxide regulation were investigated in an apneic pig model under veno-venous extracorporeal membrane oxygenation support. A predefined sequence of blood and sweep flows was tested. Results Oxygenation was mainly associated with extracorporeal membrane oxygenation blood flow (beta coefficient = 0.036mmHg/mL/min), cardiac output (beta coefficient = -11.970mmHg/L/min) and pulmonary shunting (beta coefficient = -0.232mmHg/%). Furthermore, the initial oxygen partial pressure and carbon dioxide partial pressure measurements were also associated with oxygenation, with beta coefficients of 0.160 and 0.442mmHg/mmHg, respectively. Carbon dioxide partial pressure was associated with cardiac output (beta coefficient = 3.578mmHg/L/min), sweep gas flow (beta coefficient = -2.635mmHg/L/min), temperature (beta coefficient = 4.514mmHg/ºC), initial pH (beta coefficient = -66.065mmHg/0.01 unit) and hemoglobin (beta coefficient = 6.635mmHg/g/dL). Conclusion In conclusion, elevations in blood and sweep gas flows in an apneic veno-venous extracorporeal membrane oxygenation model resulted in an increase in oxygen partial pressure and a reduction in carbon dioxide partial pressure 2, respectively. Furthermore, without the possibility of causal inference, oxygen partial pressure was negatively associated with pulmonary shunting and cardiac output, and carbon dioxide partial pressure was positively associated with cardiac output, core temperature and initial hemoglobin. PMID:27096671

  9. Inhibiting the combustion of air-acetylene mixtures

    NASA Astrophysics Data System (ADS)

    Kopylov, S. N.; Gubina, T. V.

    2016-01-01

    The effect propane, methane, and a mixture of 18 vol % C3H6-40 vol % C3H8-42 vol % C4H10 have on the combustion of air-acetylene mixtures is investigated experimentally. The upper concentration limit of flame propagation, maximum explosion pressure, and maximum rate of rise of explosion pressure are determined. It is found that propane and a mixture of 18 vol % C3H6-40 vol % C3H8-42 vol % C4H10 are strong inhibitors of combustion of acetylene in its concentration ranges of 2-8 vol %. The inhibition effect becomes weaker as the acetylene content in the mixture increases. It disappears completely at C2H2 concentrations exceeding 15 vol %. The above experimental findings are explained using the proposed scheme of acetylene oxidation.

  10. Phase stability of BSCF in low oxygen partial pressures

    SciTech Connect

    Ovenstone, James; Jung, Jae-Il; White, Jeffery S.; Edwards, Doreen D.; Misture, Scott T.

    2008-03-15

    In situ X-ray diffraction has been used to investigate the phase stability of barium strontium cobalt iron oxide (BSCF) with the formula Ba{sub 0.5}Sr{sub 0.5}Fe{sub 1-x}Co{sub x}O{sub 3-{delta}} (x=0, 0.2, 0.4, 0.6, 0.8, and 1). The thermal decomposition processes in both low partial pressures of oxygen (air -10{sup -5} atm pO{sub 2}) and in reducing conditions have been detailed. BSCF manifests excellent stability down to 10{sup -5} atm pO{sub 2}; however, it decomposes through a complex series of oxides under reducing conditions. Increasing the cobalt content results in a decrease in the temperature range of stability of the material under 4% H{sub 2} in N{sub 2}, with the initial decomposition taking place at 375, 425, 550, 600, 650 and 675 deg. C, for x=1, 0.8, 0.6, 0.4, 0.2 and 0, respectively. Further, the thermal expansion is a strong function of the oxygen activity and Co content. The x=0, 1 end member, BSC, undergoes a phase transition from rhombohedral to cubic symmetry at {approx}800 deg. C under 10{sup -5} atm pO{sub 2}, resulting in an ideal perovskite with a=3.9892(3) A at room temperature. - Graphical abstract: The phase stability of the fuel cell cathode Ba{sub 0.5}Sr{sub 0.5}Fe{sub 1-x}Co{sub x}O{sub 3-{delta}} in low pO{sub 2} and high temperature has been investigated using in situ X-ray diffraction. Both stability and thermal expansion coefficient were found to increase with increasing iron content. Decomposition products under reducing conditions have been identified.

  11. Acetylene-Terminated Polyimide Siloxanes

    NASA Technical Reports Server (NTRS)

    St. Clair, Terry L.; Maudgal, Shubba

    1987-01-01

    Siloxane-containing addition polyimides yield toughened high-temperature adhesives and matrix resins. Addition polyimide made by reaction of aromatic tetracarboxylic acid dianhydride with aromatic diamine in presence of ethynyl-substituted aromatic monoamine. Acetylene-terminated siloxane imide cured by heating to yield acetylene-terminated polyimide siloxane.

  12. Plateau Waves of Intracranial Pressure and Partial Pressure of Cerebral Oxygen.

    PubMed

    Lang, Erhard W; Kasprowicz, Magdalena; Smielewski, Peter; Pickard, John; Czosnyka, Marek

    2016-01-01

    This study investigates 55 intracranial pressure (ICP) plateau waves recorded in 20 patients after severe traumatic brain injury (TBI) with a focus on a moving correlation coefficient between mean arterial pressure (ABP) and ICP, called PRx, which serves as a marker of cerebrovascular reactivity, and a moving correlation coefficient between ABP and cerebral partial pressure of oxygen (pbtO2), called ORx, which serves as a marker for cerebral oxygen reactivity. ICP and ICPamplitude increased significantly during the plateau waves, whereas CPP and pbtO2 decreased significantly. ABP, ABP amplitude, and heart rate remained unchanged. In 73 % of plateau waves PRx increased during the wave. ORx showed an increase during and a decrease after the plateau waves, which was not statistically significant. Our data show profound cerebral vasoparalysis on top of the wave and, to a lesser extent, impairment of cerebral oxygen reactivity. The different behavior of the indices may be due to the different latencies of the cerebral blood flow and oxygen level control mechanisms. While cerebrovascular reactivity is a rapidly reacting mechanism, cerebral oxygen reactivity is slower. PMID:27165902

  13. Oxygen Partial Pressure and Oxygen Concentration Flammability: Can They Be Correlated?

    NASA Technical Reports Server (NTRS)

    Harper, Susana A.; Juarez, Alfredo; Perez, Horacio, III; Hirsch, David B.; Beeson, Harold D.

    2016-01-01

    NASA possesses a large quantity of flammability data performed in ISS airlock (30% Oxygen 526mmHg) and ISS cabin (24.1% Oxygen 760 mmHg) conditions. As new programs develop, other oxygen and pressure conditions emerge. In an effort to apply existing data, the question arises: Do equivalent oxygen partial pressures perform similarly with respect to flammability? This paper evaluates how material flammability performance is impacted from both the Maximum Oxygen Concentration (MOC) and Maximum Total Pressures (MTP) perspectives. From these studies, oxygen partial pressures can be compared for both the MOC and MTP methods to determine the role of partial pressure in material flammability. This evaluation also assesses the influence of other variables on flammability performance. The findings presented in this paper suggest flammability is more dependent on oxygen concentration than equivalent partial pressure.

  14. Forces and pressures in adsorbing partially directed walks

    NASA Astrophysics Data System (ADS)

    Janse van Rensburg, E. J.; Prellberg, T.

    2016-05-01

    Polymers in confined spaces lose conformational entropy. This induces a net repulsive entropic force on the walls of the confining space. A model for this phenomenon is a lattice walk between confining walls, and in this paper a model of an adsorbing partially directed walk is used. The walk is placed in a half square lattice {{{L}}}+2 with boundary \\partial {{{L}}}+2, and confined between two vertical parallel walls, which are vertical lines in the lattice, a distance w apart. The free energy of the walk is determined, as a function of w, for walks with endpoints in the confining walls and adsorbing in \\partial {{{L}}}+2. This gives the entropic force on the confining walls as a function of w. It is shown that there are zero force points in this model and the locations of these points are determined, in some cases exactly, and in other cases asymptotically.

  15. Potential hydrogen and oxygen partial pressures in legacy plutonium oxide packages at Oak Ridge

    SciTech Connect

    Veirs, Douglas K.

    2014-07-07

    An approach to estimate the maximum hydrogen and oxygen partial pressures within sealed containers is described and applied to a set of packages containing high-purity plutonium dioxide. The approach uses experimentally determined maximum hydrogen and oxygen partial pressures and scales the experimentally determined pressures to the relevant packaged material properties. The important material properties are the specific wattage and specific surface area (SSA). Important results from the experimental determination of maximum partial pressures are (1) the ratio of hydrogen to oxygen is stoichiometric, and (2) the maximum pressures increase with increasing initial rates of production. The material properties that influence the rates are the material specific wattage and the SSA. The unusual properties of these materials, high specific wattage and high SSA, result in higher predicted maximum pressures than typical plutonium dioxide in storage. The pressures are well within the deflagration range for mixtures of hydrogen and oxygen.

  16. Influence of oxygen partial pressure on the quasi-ternary system Cr-Mn-Ti oxide

    SciTech Connect

    Garcia-Rosales, C.; Schulze, H.A.; Naoumidis, A.; Nickel, H. . Research Centre Juelich)

    1993-11-01

    The quasi-ternary system Cr-Mn-Ti oxide was investigated at 1,000 C under oxygen partial pressures ranging from 0.21 bar to 10[sup [minus]21] bar (1 bar = 10[sup 5] Pa). X-ray diffraction analysis was used to identify phases and determine lattice parameters. The positions of phase boundaries as a function of oxygen partial pressure were measured using the emf method. The spinel MnCr[sub 2]O[sub 4] may be regarded as the most interesting compound in this system. Part of the chromium can be replaced by trivalent titanium at low oxygen partial pressures and by trivalent manganese at high pressures, and the formation of a limited solid solution with the spinel Mn[sub 2]TiO[sub 4] is possible in all cases. As a result, a coherent single-phase spinel region exists over the entire oxygen partial pressure range at 1,000 C.

  17. Method and apparatus for monitoring oxygen partial pressure in air masks

    NASA Technical Reports Server (NTRS)

    Kelly, Mark E. (Inventor); Pettit, Donald R. (Inventor)

    2006-01-01

    Method and apparatus are disclosed for monitoring an oxygen partial pressure in an air mask and providing a tactile warning to the user. The oxygen partial pressure in the air mask is detected using an electrochemical sensor, the output signal from which is provided to a comparator. The comparator compares the output signal with a preset reference value or range of values representing acceptable oxygen partial pressures. If the output signal is different than the reference value or outside the range of values, the air mask is vibrated by a vibrating motor to alert the user to a potentially hypoxic condition.

  18. Partial Pressures of Te2 and Thermodynamic Properties of Ga-Te System

    NASA Technical Reports Server (NTRS)

    Su, Ching-Hua; Curreri, Peter A. (Technical Monitor)

    2001-01-01

    The partial pressures of Te2 in equilibrium with Ga(1-x)Te(x) samples were measured by optical absorption technique from 450 to 1100 C for compositions, x, between 0.333 and 0.612. To establish the relationship between the partial pressure of Te, and the measured optical absorbance, the calibration runs of a pure Te sample were also conducted to determine the Beer's Law constants. The partial pressures of Te2 in equilibrium with the GaTe(s) and Ga2Te3(s)compounds, or the so-called three-phase curves, were established. These partial pressure data imply the existence of the Ga3Te4(s) compound. From the partial pressures of Te2 over the Ga-Te melts, partial molar enthalpy and entropy of mixing for Te were derived and they agree reasonable well with the published data. The activities of Te in the Ga-Te melts were also derived from the measured partial pressures of Te2. These data agree well with most of the previous results. The possible reason for the high activity of Te measured for x less than 0.60 is discussed.

  19. Partial molar volume of L-Valine in water under high pressure

    NASA Astrophysics Data System (ADS)

    Sawamura, Seiji

    2013-06-01

    Partial molar volume of L-valine in water was estimated up to 400 MPa from pressure coefficient of the solubility of the solute and molar volume of solid valine. The former was measured in a previous paper and the latter was measured in this article using a piston-cylinder typed cell. The partial molar volume increased with pressure and a maximum was observed around 250 MPa. It was compared with other amino acids.

  20. Effects of operating pressure on flame oscillation and emission characteristics in a partially premixed swirl combustor

    SciTech Connect

    Kim, Jong-Ryul; Choi, Gyung-Min; Kim, Duck-Jool

    2011-01-15

    The influence of varying combustor pressure on flame oscillation and emission characteristics in the partially premixed turbulent flame were investigated. In order to investigate combustion characteristics in the partially premixed turbulent flame, the combustor pressure was controlled in the range of -30 to 30 kPa for each equivalence ratio ({phi} = 0.8-1.2). The r.m.s. of the pressure fluctuations increased with decreasing combustor pressure for the lean condition. The combustor pressure had a sizeable influence on combustion oscillation, whose dominant frequency varied with the combustor pressure. Combustion instabilities could be controlled by increasing the turbulent intensity of the unburned mixture under the lean condition. An unstable flame was caused by incomplete combustion; hence, EICO greatly increased. Furthermore, EINO{sub x} simply reduced with decreasing combustor pressure at a rate of 0.035 g/10 kPa. The possibility of combustion control on the combusting mode and exhaust gas emission was demonstrated. (author)

  1. Non-invasive multiwavelength photoplethysmography under low partial pressure of oxygen.

    PubMed

    Fang, Yung Chieh; Tai, Cheng-Chi

    2016-08-01

    A reduction in partial pressure of oxygen in the environment may be caused by a gain in altitude, which reduces the atmospheric pressure; it may also be caused by the carbon dioxide generated from breathing in an enclosed space. Does inhaling oxygen of lower partial pressure affect the oxygen-carrying function of haemoglobin in vivo? This study uses non-invasive multiwavelength photoplethysmography to measure the effects that inhaling this type of oxygen can have on the plethysmography of the appendages of the body (fingertips). The results indicate that under low partial pressure of oxygen, be it the result of a gain in carbon dioxide concentration or altitude, the change in visible light absorption is the biggest for short wavelengths (approximately 620 or 640 nm) near deoxyhaemoglobin, which has higher absorption coefficient. Moreover, increasing carbon dioxide concentration from 5000 to 10,000 ppm doubly reduces the absorption rate of these short wavelengths. PMID:27337628

  2. Oxygen partial pressure effects on the magnetron sputtered WO3 films

    NASA Astrophysics Data System (ADS)

    Merhan Muğlu, G.; Gür, E.

    2016-04-01

    Electrochromism is changing color of a substance in response to the applied an external electric field and the phenomenon is reversible. WO3 is very attractive material due to its electrochromic properties as well as it is also attractive for many different applications such as gas sensors, phosphorous screen, textile, glass industry. In this study, it is aimed to provide optimization of the optical and structural characteristics of WO3 by changing the growth parameters mainly the oxygen partial pressure. The partial pressure of oxygen was changed with increments of 0.7 mTorr. For the analysis, X-ray Diffraction (XRD), absorption, Raman spectroscopy measurements were used. When O2 gas increased, peaks belong to the WO3 was observed in XRD patterns at the 2 theta angles of 23.0, 11.0, 23.5 and 28.5 angles corresponding to the (002), (020) and (220) planes, respectively. This shows that there is a significant effect of increasing O2 partial pressure in the formation of WO3 films. The bandgap energy of the WO3 thin films are found to be around 3.0 eV. Raman measurements showed vibrational modes of W-O-W stretching and bending modes which shows small shifts depending on the partial pressures of the O2. Obtained results indicated that better crystal structure is obtained with higher O2 gas partial pressure.

  3. Research in acetylene containing monomers

    NASA Technical Reports Server (NTRS)

    Ogliaruso, M. A.

    1976-01-01

    The preparation of precursor bisbenzils with pendant acetylene linkages for use in the synthesis of new aromatic poly (phenyl quinoxalines) was investigated. Attempts to condense para, para prime-dibromo benzil and potassium acetylide in liquid ammonia and in toluene, to prepare 4-phenyl acetyl phenyl ether, 4-(paraacetylphenyl) acetyl phenyl ether, 4-phenyl acetyl-4 primeacetyl phenyl acetyl phenyl ether, the reaction of 4-phenyl acetyl phenyl ether with Villsmeier reagent to prepare 4-(beta-chloro cinnamaldehyde) phenyl ether, the reaction of 4-(para-acetyl phenyl) acetyl phenyl ether with Villsmeier reagent, and the oxidation of bibenzil to prepare benzil are described. The reactions of phenyl acetylene with oxidizing agent, of phenyl acetylene with bromine, of 1,1,2,2-tetrabromo ethyl benzene with zinc and with oxidizing agent are described.

  4. Partial pressures of oxygen, phosphorus and fluorine in some lunar lavas

    NASA Technical Reports Server (NTRS)

    Nash, W. P.; Hausel, W. D.

    1973-01-01

    Lunar sample 14310 is a feldspar-rich basalt which shows no evidence of shock deformation or recrystallization. Pyroxenes include Mg-rich orthopyroxene, pigeonite and augite; pyroxferroite occurs in the interstitial residuum. Plagioclase feldspars are zoned from An(96) to An(67), and variations in feldspar compositions do not necessarily indicate loss of Na during eruption of the lava. Opaque phases include ilmenite, ulvospinel, metallic iron, troilite, and schreibersite. Both whitlockite and apatite are present, and the interstitial residua contain baddeleyite, tranquillityite and barium-rich sanidine. Theoretical calculations provide estimates of partial pressures of oxygen, phosphorus, and fluorine in lunar magmas. In general, partial pressures of oxygen are restricted by the limiting assemblages of iron-wuestite and ilmenite-iron-rutile; phosphorus partial pressures are higher in lunar magmas than in terrestrial lavas. The occurrence of whitlockite indicates significantly lower fugacities of fluorine in lunar magmas than in terrestrial magmas.

  5. Effects of Oxygen Partial Pressure on the Surface Tension of Liquid Nickel

    NASA Technical Reports Server (NTRS)

    SanSoucie, Michael P.; Rogers, Jan R.; Gowda, Vijaya Kumar Malahalli Shankare; Rodriguez, Justin; Matson, Douglas M.

    2015-01-01

    The NASA Marshall Space Flight Center's electrostatic levitation (ESL) laboratory has been recently upgraded with an oxygen partial pressure controller. This system allows the oxygen partial pressure within the vacuum chamber to be measured and controlled, theoretically in the range from 10-36 to 100 bar. The oxygen control system installed in the ESL laboratory's main chamber consists of an oxygen sensor, oxygen pump, and a control unit. The sensor is a potentiometric device that determines the difference in oxygen activity in two gas compartments (inside the chamber and the air outside of the chamber) separated by an electrolyte, which is yttria-stabilized zirconia. The pump utilizes coulometric titration to either add or remove oxygen. The system is controlled by a desktop control unit, which can also be accessed via a computer. The controller performs temperature control for the sensor and pump, PID-based current loop, and a control algorithm. Oxygen partial pressure has been shown to play a significant role in the surface tension of liquid metals. Oxide films or dissolved oxygen may lead to significant changes in surface tension. The effects of oxygen partial pressure on the surface tension of undercooled liquid nickel will be analyzed, and the results will be presented. The surface tension will be measured at several different oxygen partial pressures while the sample is undercooled. Surface tension will be measured using the oscillating drop method. While undercooled, each sample will be oscillated several times consecutively to investigate how the surface tension behaves with time while at a particular oxygen partial pressure.

  6. The adaptive control system of acetylene generator

    NASA Astrophysics Data System (ADS)

    Kovaliuk, D. O.; Kovaliuk, Oleg; Burlibay, Aron; Gromaszek, Konrad

    2015-12-01

    The method of acetylene production in acetylene generator was analyzed. It was found that impossible to provide the desired process characteristics by the PID-controller. The adaptive control system of acetylene generator was developed. The proposed system combines the classic controller and fuzzy subsystem for controller parameters tuning.

  7. Spectroscopic study of acetylene and hydrogen cyanide

    NASA Astrophysics Data System (ADS)

    Rozario, Hoimonti Immaculata

    High-resolution molecular spectroscopy has been used to study acetylene line parameters and emission spectra of hydrogen cyanide. All acetylene spectra were recorded in our laboratory at the University of Lethbridge using a 3-channel tuneable diode laser spectrometer. N2-broadened line widths and N2-pressure induced line shifts have been measured for transitions in the v1+v3 band of acetylene at seven temperatures in the range 213-333K to obtain the temperature dependences of broadening and shift coefficients. The Voigt and hard-collision line profile models were used to retrieve the line parameters. The line-broadening and line-shift coefficients as well as their temperature-dependent parameters have been also evaluated theoretically, in the frame work of a semi-classical approach based on an exponential representation of the scattering operator, an intermolecular potential composed of electrostatic quadrupole--quadrupole and pairwise atom--atom interactions as well as on exact trajectories driven by an effective isotropic potential. The experimental results for both N2-broadening and shifting show good agreement with the theoretical results. We have studied the line intensities of the 1vl 20←0v120 band system from the HCN emission spectrum. The infrared emission spectrum of H12C 14N was measured at the Justus-Liebig University, Giessen, Germany. The emission spectrum was analyzed with the spectrum analysis software Symath running using Mathematica as a platform. This approach allowed us to retrieve information on band intensity parameters.

  8. Effects of hydrogen partial pressure on autotrophic growth and product formation of Acetobacterium woodii.

    PubMed

    Kantzow, Christina; Weuster-Botz, Dirk

    2016-08-01

    Low aqueous solubility of the gases for autotrophic fermentations (e.g., hydrogen gas) results in low productivities in bioreactors. A frequently suggested approach to overcome mass transfer limitation is to increase the solubility of the limiting gas in the reaction medium by increasing the partial pressure in the gas phase. An increased inlet hydrogen partial pressure of up to 2.1 bar (total pressure of 3.5 bar) was applied for the autotrophic conversion of hydrogen and carbon dioxide with Acetobacterium woodii in a batch-operated stirred-tank bioreactor with continuous gas supply. Compared to the autotrophic batch process with an inlet hydrogen partial pressure of 0.4 bar (total pressure of 1.0 bar) the final acetate concentration after 3.1 days was reduced to 50 % (29.2 g L(-1) compared to 59.3 g L(-1)), but the final formate concentration was increased by a factor of 18 (7.3 g L(-1) compared to 0.4 g L(-1)). Applying recombinant A. woodii strains overexpressing either genes for enzymes in the methyl branch of the Wood-Ljungdahl pathway or the genes phosphotransacetylase and acetate kinase at an inlet hydrogen partial pressure of 1.4 bar reduced the final formate concentration by up to 40 % and increased the final dry cell mass and acetate concentrations compared to the wild type strain. Solely the overexpression of the two genes for ATP regeneration at the end of the Wood-Ljungdahl pathway resulted in an initial switch off of formate production at increased hydrogen partial pressure until the maximum of the hydrogen uptake rate was reached. PMID:27059835

  9. Optimizing the physical ergonomics indices for the use of partial pressure suits.

    PubMed

    Ding, Li; Li, Xianxue; Hedge, Alan; Hu, Huimin; Feathers, David; Qin, Zhifeng; Xiao, Huajun; Xue, Lihao; Zhou, Qianxiang

    2015-03-01

    This study developed an ergonomic evaluation system for the design of high-altitude partial pressure suits (PPSs). A total of twenty-one Chinese males participated in the experiment which tested three types of ergonomics indices (manipulative mission, operational reach and operational strength) were studied using a three-dimensional video-based motion capture system, a target-pointing board, a hand dynamometer, and a step-tread apparatus. In total, 36 ergonomics indices were evaluated and optimized using regression and fitting analysis. Some indices that were found to be linearly related and redundant were removed from the study. An optimal ergonomics index system was established that can be used to conveniently and quickly evaluate the performance of different pressurized/non-pressurized suit designs. The resulting ergonomics index system will provide a theoretical basis and practical guidance for mission planners, suit designers and engineers to design equipment for human use, and to aid in assessing partial pressure suits. PMID:25479976

  10. TEMPERATURE-HYDROSTATIC PRESSURE STUDIES ON PARTIALLY PURIFIED INORGANIC PYROPHOSPHATASE ACTIVITY.

    PubMed

    MORITA, R Y; MATHEMEIER, P F

    1964-12-01

    Morita, Richard Y. (Oregon State University, Corvallis), and Paul F. Mathemeier. Temperature-hydrostatic pressure studies on partially purified inorganic pyrophosphatase activity. J. Bacteriol. 88:1667-1671. 1964.-Partially purified inorganic pyrophosphatase from Bacillus stearothermophilus demonstrated increased activity at 90 C with hydrostatic pressures of 100 to 1,100 atm. At 90 C, optimal activity was at 700 atm. No enzyme activity could be demonstrated at 100 C at 1 atm; however, at 105 C moderate hydrostatic pressures favored the enzyme reaction, resulting in increased activity. The increased enzyme activity is explained on the basis of pressure counteracting the molecular volume increase which results from elevated temperature. Thermal denaturation studies at 90 C show inorganic pyrophosphatase to be more stable in the presence of cofactor than substrate, and indicate an enyzme-cofactor intermediate in the hydrolysis. PMID:14240955

  11. On the sensitivity to partial pressure of oxygen of the mobility in cadmium oxide

    NASA Astrophysics Data System (ADS)

    Grado-Caffaro, M. A.; Grado-Caffaro, M.

    2015-11-01

    The partial pressure of oxygen during the deposition process of cadmium oxide is a crucial quantity whose influence on the electrical and optical properties of this material is really very significant (consider, for example, the experimental technique known as activated reactive evaporation). In fact, this paper is a theoretical formulation to evaluate the sensitivity changes of the aforementioned pressure of the electron drift-mobility and velocity in CdO. Indeed, as we will see later, given that the electron relaxation time depends upon the oxygen partial pressure, then the electron drift-mobility, mean free path and velocity also depend on this pressure. Relevant calculations involving the above physical quantities are carried out.

  12. Releasing H2 molecules with a partial pressure difference without the use of temperature

    NASA Astrophysics Data System (ADS)

    Lee, Hoonkyung; Huang, Bing; Duan, Wenhui; Ihm, Jisoon

    2010-08-01

    Using the pseudopotential density-functional method as well as equilibrium thermodynamic functions, we explore the process of releasing H2 molecules adsorbed on a transition-metal atom caused by the hydrogen-ammonia partial pressure difference. The H2 molecules bind to a transition-metal atom at H2 pressure- NH3 pressure-temperature 50atm-10-9atm-25°C , and they are released at 3atm-10-6atm-25°C . This process involves the same mechanism responsible for carbon monoxide poisoning of hemoglobin with the O2-CO partial pressure difference. We show that our findings can be applicable to an approach to induce hydrogen desorption on nanostructured hydrogen-storage materials without the need for increasing temperature.

  13. Report on ISS O2 Production, Gas Supply and Partial Pressure Management

    NASA Technical Reports Server (NTRS)

    Schaezler, Ryan N.; Cook, Anthony J.

    2015-01-01

    Oxygen is used on International Space Station (ISS) for metabolic support and denitrogenation procedures prior to Extra-Vehicular Activities. Nitrogen is used to maintain total pressure and account for losses associated with leakage and operational losses. Oxygen and nitrogen have been supplied by various visiting vehicles such as the Progress and Shuttle in addition to the on-orbit oxygen production capability. Starting in 2014, new high pressure oxygen/nitrogen tanks are available to launch on commercial cargo vehicles and will replace the high pressure gas source that Shuttle used to provide. To maintain a habitable atmosphere the oxygen and nitrogen partial pressures are controlled between upper and lower bounds. The full range of the allowable partial pressures along with the increased ISS cabin volume are utilized as a buffer allowing days to pass between oxygen production or direct addition of oxygen and nitrogen to the atmosphere from reserves. This paper summarizes the amount of gas supplied and produced from all of the sources and describes past experience of managing partial pressures along with the range of management options available to the ISS.

  14. Efficient All-Vacuum Deposited Perovskite Solar Cells by Controlling Reagent Partial Pressure in High Vacuum.

    PubMed

    Hsiao, Sheng-Yi; Lin, Hong-Lin; Lee, Wei-Hung; Tsai, Wei-Lun; Chiang, Kai-Ming; Liao, Wei-Yu; Ren-Wu, Chen-Zheng; Chen, Chien-Yu; Lin, Hao-Wu

    2016-08-01

    All-vacuum-deposited perovskite solar cells produced by controlling reagent partial pressure in high vacuum with newly developed multi-layer electron and hole transporting structures show outstanding power conversion efficiency of 17.6% and smooth, pinhole-free, micrometer-sized perovskite crystal grains. PMID:27226143

  15. Measurement and Control of Oxygen Partial Pressure in an Electrostatic Levitator

    NASA Technical Reports Server (NTRS)

    SanSoucie, Michael P.; Rogers, Jan R.

    2014-01-01

    Recently the NASA Marshall Space Flight Center electrostatic levitation (ESL) laboratory has been upgraded to include an oxygen control system. This system allows the oxygen partial pressure within the vacuum chamber to be measured and controlled, at elevated temperatures, theoretically in the range from 10(exp -36) to 10(exp 0) bar. The role of active surface agents in liquid metals is fairly well known; however, published surface tension data typically has large scatter, which has been hypothesized to be caused by the presence of oxygen. The surface tension of metals is affected by even a small amount of adsorption of oxygen. It has even been shown that oxygen partial pressures may need to be as low as 10(exp -24) bar to avoid oxidation. While electrostatic levitation is done under high vacuum, oxide films or dissolved oxygen may have significant effects on materials properties, such as surface tension and viscosity. Therefore, the ability to measure and control the oxygen partial pressure within the chamber is highly desirable. The oxygen control system installed at MSFC contains a potentiometric sensor, which measures the oxygen partial pressure, and an oxygen ion pump. In the pump, a pulse-width modulated electric current is applied to yttrium-stabilized zirconia, resulting in oxygen transfer into or out of the system. Also part of the system is a control unit, which consists of temperature controllers for the sensor and pump, PID-based current loop for the ion pump, and a control algorithm. This system can be used to study the effects of oxygen on the thermophysical properties of metals, ceramics, glasses, and alloys. It can also be used to provide more accurate measurements by processing the samples at very low oxygen partial pressures. The oxygen control system will be explained in more detail and an overview of its use and limitations in an electrostatic levitator will be described. Some preliminary measurements have been made, and the results to date will

  16. Oxidation of C/SiC Composites at Reduced Oxygen Partial Pressures

    NASA Technical Reports Server (NTRS)

    Opila, E. J.; Serra, J. L.

    2007-01-01

    T-300 carbon fibers and T-300 carbon fiber reinforced silicon carbide composites (C/SiC) were oxidized in flowing reduced oxygen partial pressure environments at a total pressure of one atmosphere (0.5 atm O2, 0.05 atm O2 and 0.005 atm O2, balance argon). Experiments were conducted at four temperatures (816deg, 1149deg, 1343deg, and 1538 C). The oxidation kinetics were monitored using thermogravimetric analysis. T-300 fibers were oxidized to completion for times between 0.6 and 90 h. Results indicated that fiber oxidation kinetics were gas phase diffusion controlled. Oxidation rates had an oxygen partial pressure dependence with a power law exponent close to one. In addition, oxidation rates were only weakly dependent on temperature. The C/SiC coupon oxidation kinetics showed some variability, attributed to differences in the number and width of cracks in the SiC seal coat. In general, weight losses were observed indicating oxidation of the carbon fibers dominated the oxidation behavior. Low temperatures and high oxygen pressures resulted in the most rapid consumption of the carbon fibers. At higher temperatures, the lower oxidation rates were primarily attributed to crack closure due to SiC thermal expansion, rather than oxidation of SiC since these reduced rates were observed even at the lowest oxygen partial pressures where SiC oxidation is minimal.

  17. Partial alignment and measurement of residual dipolar couplings of proteins under high hydrostatic pressure

    PubMed Central

    Fu, Yinan; Wand, A. Joshua

    2013-01-01

    High-pressure NMR spectroscopy has emerged as a complementary approach for investigating various structural and thermodynamic properties of macromolecules. Noticeably absent from the array of experimental restraints that have been employed to characterize protein structures at high hydrostatic pressure is the residual dipolar coupling, which requires the partial alignment of the macromolecule of interest. Here we examine five alignment media that are commonly used at ambient pressure for this purpose. We find that the spontaneous alignment of Pf1 phage, d(GpG) and a C12E5/n-hexnanol mixture in a magnetic field is preserved under high hydrostatic pressure. However, DMPC/ DHPC bicelles and collagen gel are found to be unsuitable. Evidence is presented to demonstrate that pressure-induced structural changes can be identified using the residual dipolar coupling. PMID:23807390

  18. [Device to assess in-socket pressure distribution for partial foot amputation].

    PubMed

    Alvarez-Camacho, Michelín; Urrusti, José Luis; Acero, María Del Carmen; Galván Duque-Gastélum, Carlos; Rodríguez-Reyes, Gerardo; Mendoza-Cruz, Felipe

    2014-07-01

    A device for dynamic acquisition and distribution analysis of in-socket pressure for patients with partial foot amputation is presented in this work. By using the developed system, we measured and generated pressure distribution graphs, obtained maximal pressure, and calculated pressure-time integral (PTI) of three subjects with partial foot amputation and of a group of Healthy subjects (Hs) (n = 10). Average maximal pressure in the healthy group was 19.4 ± 4.11 PSI, while for the three amputated patients, this was 27.8 ± 1.38, 17.6 ± 1.15, 29.10 ± 3.9 PSI, respectively. Maximal pressure-time integral for healthy subjects was 11.56 ± 2.83 PSI*s, and for study subjects was 19.54 ± 1.9, 12.35 ± 1.48, and 13.17 ± 1.31 PSI*s, respectively. The results of the control group agree with those previously reported in the literature. The pressure distribution pattern showed clear differences between study subjects and those of the control group; these graphs allowed us to identify the pressure in regions-of-interest that could be critical, such as surgical scars. The system presented in this work will aid to assess the effectiveness with which prosthetic systems distribute load, given that the formation of ulcers is highly linked to the pressure exercised at the point of contact; in addition, these results will help to investigate the comfort perception of the prosthesis, a factor directly influenced by the stump's pressure distribution. PMID:25264793

  19. Transient responses of nitrogenase to acetylene and oxygen in actinorhizal nodules and cultured Frania

    SciTech Connect

    Silvester, W.B.; Winship, L.J. )

    1990-02-01

    Nitrogenase activity in root nodules of four species of actinorhizal plants showed varying declines in response to exposure to acetylene (10% v/v). Gymnostoma papuanum (S.Moore) L. Johnson. and Casuarina equisetifolia L. nodules showed a small decline (5-15%) with little or no recovery over 15 minutes. Myrica gale L. nodules showed a sharp decline followed by a rapid return to peak activity. Alnus incana ssp. rugosa (Du Roi) Clausen. nodules usually showed varying degrees of decline followed by a slower return to peak or near-peak activity. We call these effects acetylene-induced transients. Rapid increases in oxygen tension also caused dramatic transient decreases in nitrogenase activity in all species. The magnitude of the transient decrease was related to the size of the O{sub 2} partial pressure (pO{sub 2}) rise, to the proximity of the starting and ending oxygen tensions to the pO{sub 2} optimum, and to the time for which the plant was exposed to the lower pO{sub 2}. Oxygen-induced transients, induced both by step jumps in pO{sub 2} and by O{sub 2} pulses, were also observed in cultures of Frankia. The effects seen in nodules are purely a response by the bacterium and not a nodule effect per se. Oxygen-induced nitrogenase transients in actinorhizal nodules from the plant genera tested here do not appear to be a result of changes in nodule diffusion resistance.

  20. Acetylene-terminated polyimide adhesives

    NASA Technical Reports Server (NTRS)

    Hanky, A. O.

    1983-01-01

    The nadic-encapped LARC-13 addition polyimide exhibits excellent flow, is easy to process, and can be utilized for short terms at temperatures up to 593 C. It retains good lap shear strength as an adhesive for titanium after aging in air up to 125 hours at 316 C; but lap shear strength degrades with longer exposures at that temperature. Thermid 600, an addition polyimide that is acetylene encapped, exhibits thermomechanical properties even after long term exposure in at air at 316 C. An inherent drawback of this system is that it has a narrow processing window. An acetylene encapped, addition polyimide which is a hybrid of these two systems was developed. It has good retention of strength after long term aging and is easily processed. The synthesis and characterization of various molecular weight oligomers of this system are discussed as well as the bonding, aging, and testing of lap shear adhesive samples.

  1. Acetylene-terminated polyimide adhesives

    NASA Technical Reports Server (NTRS)

    Hanky, A. O.; St. Clair, T. L.

    1983-01-01

    The nadic-encapped LARC-43 addition polyimide exhibits excellent flow, is easy to process, and can be utilized for short terms at temperatures up to 593 C. It retains good lap shear strength as an adhesive for titanium after aging in air up to 125 hours at 316 C; but lap shear strength degrades with longer exposures at that temperature. Thermid 600, an addition polyimide that is acetylene encapped, exhibits thermomechanical properties even after long term exposure in at air at 316 C. An inherent drawback of this system is that it has a narrow processing window. An acetylene encapped, addition polyimide which is a hybrid of these two systems was developed. It has good retention of strength after long term aging and is easily processed. The synthesis and characterization of various molecular weight oligomers of this system are discussed as well as the bonding, aging, and testing of lap shear adhesive samples. Previously announced in STAR as N83-18910

  2. Carbon dioxide reduction to methane and coupling with acetylene to form propylene catalyzed by remodeled nitrogenase

    PubMed Central

    Yang, Zhi-Yong; Moure, Vivian R.; Dean, Dennis R.; Seefeldt, Lance C.

    2012-01-01

    A doubly substituted form of the nitrogenase MoFe protein (α-70Val→Ala, α-195His→Gln) has the capacity to catalyze the reduction of carbon dioxide (CO2) to yield methane (CH4). Under optimized conditions, 1 nmol of the substituted MoFe protein catalyzes the formation of 21 nmol of CH4 within 20 min. The catalytic rate depends on the partial pressure of CO2 (or concentration of HCO3−) and the electron flux through nitrogenase. The doubly substituted MoFe protein also has the capacity to catalyze the unprecedented formation of propylene (H2C = CH-CH3) through the reductive coupling of CO2 and acetylene (HC≡CH). In light of these observations, we suggest that an emerging understanding of the mechanistic features of nitrogenase could be relevant to the design of synthetic catalysts for CO2 sequestration and formation of olefins. PMID:23150564

  3. Flight test evaluation of an RAF high altitude partial pressure protective assembly

    NASA Technical Reports Server (NTRS)

    Ashworth, G. R.; Putnam, T. W.; Dana, W. J.; Enevoldson, E. K.; Winter, W. R.

    1979-01-01

    A partial pressure suit was evaluated during tests in an F-104 and F-15 as a protective garment for emergency descents. The garment is an pressure jerkin and modified anti-g suit combined with an oronasal mask. The garment can be donned and doffed at the aircraft to minimize thermal buildup. The oronasal mask was favored by the pilots due to its immobility on the face during high g-loading. The garment was chosen to provide optimum dexterity for the pilot, which is not available in a full pressure suit, while protecting the pilot at altitudes up to 18,288 meters, during a cabin decompression, and subsequent aircraft descent. During cabin decompressions in the F-104 and F-15, cabin pressure altitude was measured at various aircraft angles of attack, Mach numbers, and altitudes to determine the effect of the aerodynamic slipstream on the cabin altitude.

  4. Oxidation of C/SiC Composites at Reduced Oxygen Partial Pressures

    NASA Technical Reports Server (NTRS)

    Opila, Elizabeth J.; Serra, Jessica

    2009-01-01

    Carbon-fiber reinforced SiC (C/SiC) composites are proposed for leading edge applications of hypersonic vehicles due to the superior strength of carbon fibers at high temperatures (greater than 1500 C). However, the vulnerability of the carbon fibers in C/SiC to oxidation over a wide range of temperatures remains a problem. Previous oxidation studies of C/SiC have mainly been conducted in air or oxygen, so that the oxidation behavior of C/SiC at reduced oxygen partial pressures of the hypersonic flight regime are less well understood. In this study, both carbon fibers and C/SiC composites were oxidized over a wide range of temperatures and oxygen partial pressures to facilitate the understanding and modeling of C/SiC oxidation kinetics for hypersonic flight conditions.

  5. Oxygen partial pressure dependent electrical conductivity type conversion of phosphorus-doped ZnO thin films

    NASA Astrophysics Data System (ADS)

    Lee, S.; Jeong, Y. E.; Lee, D.; Bae, J. S.; Lee, W. J.; Park, K. H.; Bu, S. D.; Park, S.

    2014-02-01

    In this study, the oxygen partial pressure dependent physical properties of phosphorous-doped ZnO thin films were investigated. All thin films, grown on Al2O3(0 0 0 1) substrates using pulsed laser deposition, exhibited (0 0 2) orientation regardless of the oxygen partial pressure. However, as the oxygen partial pressure increased, the degree of crystallinity and the concentration of oxygen vacancies in the films decreased. All the thin-film samples showed n-type characteristics except for a sample grown at 100 mTorr, which exhibited p-type characteristics. The optical band gap energy also changed with the oxygen partial pressure. The feasible microscopic mechanism of conductivity conversion is explained in terms of the lattice constant, crystallinity, and the relative roles of the substituted phosphorous in the Zn-site and/or oxygen vacancies depending on the oxygen partial pressure.

  6. Development of an infrared absorption transducer to monitor partial pressure of carbon dioxide for space applications

    NASA Technical Reports Server (NTRS)

    Lutz, Glenn; Margiott, Victoria; Murray, Sean; Schaff, James

    1993-01-01

    An infrared (IR) carbon dioxide (CO2) transducers has been designed, developed, and produced for space applications. The transducer provides measurement of partial pressure of CO2 in life support applications, including the Extravehicular Mobility Unit (EMU), Space Shuttle Orbiter and Spacehab. The electrochemical sensor presently used for these applications has a slow reponse time and has reliability concerns due to the electrolyte. The new microprocessor based unit has a fast response time and can be tailored to other space applications.

  7. Introduction to total- and partial-pressure measurements in vacuum systems

    NASA Technical Reports Server (NTRS)

    Outlaw, R. A.; Kern, F. A.

    1989-01-01

    An introduction to the fundamentals of total and partial pressure measurement in the vacuum regime (760 x 10 to the -16th power Torr) is presented. The instrument most often used in scientific fields requiring vacuum measurement are discussed with special emphasis on ionization type gauges and quadrupole mass spectrometers. Some attention is also given to potential errors in measurement as well as calibration techniques.

  8. Thermal Conversion of Methane to Acetylene

    SciTech Connect

    Fincke, James Russell; Anderson, Raymond Paul; Hyde, Timothy Allen; Wright, Randy Ben; Bewley, Randy Lee; Haggard, Delon C; Swank, William David

    2000-01-01

    This report describes the experimental demonstration of a process for the direct thermal conversion of methane to acetylene. The process utilizes a thermal plasma heat source to dissociation products react to form a mixture of acetylene and hydrogen. The use of a supersonic expansion of the hot gas is investigated as a method of rapidly cooling (quenching) the product stream to prevent further reaction or thermal decomposition of the acetylene which can lower the overall efficiency of the process.

  9. Partially penetrating fractures: Pressure transient analysis of an infinite conductivity fracture

    SciTech Connect

    Rodriguez, F.; Cinco-Ley, H.; Horne, R.N.

    1984-04-01

    The effect of the partial penetration of an infinite conductivity fracture on the transient pressure behavior of a vertically fractured well is investigated. Analysis of results shows that the pressure behavior of a well intersected by a partially-penetrating infinite conductivity vertical fracture can be divided into three flow periods: 1) the early time flow period which is characterized by a formation linear flow as in the case of a fully-penetrating infinite-conductivity vertical fracture, 2) the infinite-acting flow period and 3) the pseudoradial flow period which develops after the effects of the vertical boundaries of the reservoir are felt in the pressure behavior of the well. A log-log graph of log(h /SUB f/ /h)p /SUB wD/ versus log t /SUB Dxf/ shows a slope of one half during the early time flow period of a well with an infinite-conductivity partially penetrating fracture. The time for the end of the early time flow period is directly related to the square of the dimensionless height of the fracture, h /SUB fD/, which is defined as the ratio between the height of the fracture and its half length.

  10. Biomass hydrolysis inhibition at high hydrogen partial pressure in solid-state anaerobic digestion.

    PubMed

    Cazier, E A; Trably, E; Steyer, J P; Escudie, R

    2015-08-01

    In solid-state anaerobic digestion, so-called ss-AD, biogas production is inhibited at high total solids contents. Such inhibition is likely caused by a slow diffusion of dissolved reaction intermediates that locally accumulate. In this study, we investigated the effect of H2 and CO2 partial pressure on ss-AD. Partial pressure of H2 and/or CO2 was artificially fixed, from 0 to 1 557mbars for H2 and from 0 to 427mbars for CO2. High partial pressure of H2 showed a significant effect on methanogenesis, while CO2 had no impact. At high [Formula: see text] , the overall substrate degradation decreased with no accumulation of metabolites from acidogenic bacteria, indicating that the hydrolytic activity was specifically impacted. Interestingly, such inhibition did not occur when CO2 was added with H2. This result suggests that CO2 gas transfer is probably a key factor in ss-AD from biomass. PMID:25935390

  11. Acetylene terminated aspartimides and resins therefrom

    NASA Technical Reports Server (NTRS)

    Hergenrother, Paul M. (Inventor); Connell, John W. (Inventor); Havens, Stephen J. (Inventor)

    1989-01-01

    Acetylene terminated aspartimides are prepared using two methods. In the first, an amino-substituted aromatic acetylene is reacted with an aromatic bismaleimide in a solvent of glacial acetic acid and/or m-cresol. In the second method, an aromatic diamine is reacted with an ethynyl containing maleimide, such an N-(3-ethynyl phenyl) maleimide, in a solvent of glacial acetic acid and/or m-cresol. In addition, acetylene terminated aspartimides are blended with various acetylene terminated oligomers and polymers to yield composite materials exhibiting improved mechanical properties.

  12. Pressures of Partial Crystallization of Magmas from the Juan de Fuca Ridge: Implications for Crustal Accretion

    NASA Astrophysics Data System (ADS)

    Scott, J. L.; Barton, M.

    2010-12-01

    Plate spreading at the mid-ocean ridges is accompanied by intrusion of dikes and eruption of lava along the ridge axis. It has been suggested that the depth of magma chambers that feed the flows and dikes is related to the rate of spreading. As part of a larger effort to examine this hypothesis, we determined the depths of magma chambers beneath the intermediate spreading Juan de Fuca Ridge (JdF) which extends from the Blanco fracture zone at about 44.5 degrees North to the Triple junction of the JdF, Nootka Fault, and the Socanco fracture zone at 48.7 degrees North. Pressures of partial crystallization were determined by comparing the compositions of natural liquids (glasses) with those of experimental liquids in equilibrium with olivine, plagioclase, and clinopyroxene at different pressures and temperatures using the method described by Kelley and Barton (2008). Chemical analyses mid-ocean ridge basalts glasses sampled from along the JdF were used as liquid compositions. Samples with anomalous chemical compositions and samples that yielded pressures associated with unrealistically large uncertainties were filtered out of the database. The calculated pressures for the remaining 533 samples were used to calculate the depths of partial crystallization and to identify the likely location of magma chambers. Preliminary results indicate that the pressure of partial crystallization decreases from 2 to 1±0.5 kbars from the Blanco fracture zone to the north along the Cleft segment of the ridge. Calculated pressures remain approximately constant at 0.87±0.53 kbars along ridge segments to the north of the Cleft. These low pressures for the remaining segments of the ridge are interpreted to indicate magma chambers at depths of 1.3-4.9 km and agree reasonably well with the depths of seismically imaged tops of axial magma chambers (2-3 km) (Canales et al 2009). The higher pressures obtained for lavas erupted along the Cleft segment of the JdF agree very well with recent

  13. Preliminary Measurements Of N2O Partial Pressures In Rivers of Amazon Basin, Brazil

    NASA Astrophysics Data System (ADS)

    Oliveira, C. B.; Rasera, M. F.; Krusche, A. V.; Victoria, R. L.; Richey, J. E.; Cunha, H. B.; Gomes, B. M.

    2006-12-01

    The concentrations of nitrous oxide (N2O), an important component of the greenhouse effect and with a long residence time in the atmosphere, have significantly increased in this century. The reasons for this atmospheric increase in N2O are still partially unexplained. This uncertainty is worse in relation to aquatic environments. Here we report on preliminary measurements of N2O partial pressures in rivers of the Amazon basin. The study areas are in the state of Rondonia (rivers Ji Parana, Urupa, Comemoracao and Pimenta Bueno) and Amazonas (rivers Solimoes and Negro). The rivers were sampled from October 2005 to April 2006, using with immersion pumps, lowered in the middle of the channel to 60% of total depth. Water was pumped directly into a 1 l plastic bottle, which was overflown three times before closing. Using syringes, 60 ml of N2 were injected into the bottle, simultaenously to the withdrawn of 60 ml of sample. N2O was extracted into these 60 ml of N2 by shaking vigorously for 2 minutes. With the same syringes, the gas was taken from the bottles and injected into sealed evacuated 25 ml vials. Atmospheric samples were taken from one meter above the water column and stored the same way. N2O partial pressures were determined on a Shimadzu GC-14 Green House Gas Analyzer. All rivers showed little variations in N2O partial pressures. Average values in the rivers of Rondonia were around 0.41 ± 0.07 μ atm (n=46), whereas the Solimoes and Negro rivers, in the state of Amazonas, showed values around 0.43 ± 0.08 μ atm (n=131). Atmospheric averages were approximately 0.34 ± 0.04 μ atm (n=58) and 0.32 ± 0.03 μ atm (n=134) in the states of Rondonia and Amazonas, respectively. This means that, although these waters are supersatured in CO2, making evasive fluxes of this gas an important component of the C cycle in this basin, the same does not occur in the N cycle. Small differences in partial pressures of N2O between water and air will result in small fluxes of

  14. Influence of Oxygen Partial Pressure on the Fermi Level of ZnO Films Investigated by Kelvin Probe Force Microscopy

    NASA Astrophysics Data System (ADS)

    Su, Ting; Zhang, Hai-Feng

    2012-12-01

    The influence of oxygen partial pressure on the Fermi level of ZnO films prepared by pulsed laser deposition is investigated. The contact potential difference of the ZnO films fabricated under various oxygen partial pressures is studied systematically using Kelvin probe force microscopy. The Fermi level shifted by 0.35 eV as oxygen partial pressure increased. This indicates a significant change in the electronic structure and energy balance in ZnO films. This fact provides a consistent explanation that the changes in carrier concentration, resistivity and mobility of ZnO films are attributed to oxygen vacancy induced shift of the Fermi level.

  15. Influence of oxygen partial pressure on the physical properties of Ag doped NiO thin films

    NASA Astrophysics Data System (ADS)

    Reddy, Y. Ashok Kumar; Reddy, A. Sivasankar; Reddy, P. Sreedhara

    2013-06-01

    Ag doped p-type NiO thin films were successfully deposited by DC reactive magnetron sputtering technique at different oxygen partial pressures in the range 1 × 10-4 - 9 × 10-4 mbar. The structural and morphological properties of the films were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). All the deposited films were of polycrystalline nature and exhibited cubic structure with preferential growth. The morphological studies revealed that the surface roughness was increased with increasing oxygen partial pressure up to 5 × 10-4 mbar and decreased at higher oxygen partial pressures.

  16. Proximate nutritional composition of CELSS crops grown at different CO2 partial pressures

    NASA Technical Reports Server (NTRS)

    Wheeler, R. M.; Mackowiak, C. L.; Sager, J. C.; Knott, W. M.; Berry, W. L.

    1994-01-01

    Two Controlled Ecological Life Support System (CELSS) candidate crops, soybean (Glycine max) and potato (Solanum tuberosum), were grown hydroponically in controlled environments maintained at carbon dioxide (CO2) partial pressures ranging from 0.05 to 1.00 kPa (500 to 10,000 ppm at 101 kPa atmospheric pressure). Plants were harvested at maturity (90 days for soybean and 105 days for potato) and all tissues analyzed for proximate nutritional composition (i.e. protein, fat, carbohydrate, crude fiber, and ash content). Soybean seed ash and crude fiber were higher and carbohydrate was lower than values reported for field-grown seed. Potato tubers showed little difference from field-grown tubers. Crude fiber of soybean stems and leaves increased with increased CO2, as did soybean leaf protein (total nitrogen). Potato leaf and stem (combined) protein levels also increased with increased CO2, while leaf and stem carbohydrates decreased. Values for leaf and stem protein and ash were higher than values generally reported for field-grown plants for both species. Results suggest that CO2 partial pressure should have little influence on proximate composition of potato tubers or soybean seed, but that high ash and protein levels might be expected from leaves and stems of crops grown in controlled environments of a CELSS.

  17. Proximate nutritional composition of celss crops grown at different CO2 partial pressures

    NASA Astrophysics Data System (ADS)

    Wheeler, R. M.; Mackowiak, C. L.; Sager, J. C.; Knott, W. M.; Berry, W. L.

    1994-11-01

    Two CELSS candidate crops, soybean (Glycine max) and potato (Solanum tuberosum), were grown hydroponically in controlled environments maintained at carbon dioxide (CO2) partial pressures ranging from 0.05 to 1.00 kPa (500 to 10,000 ppm at 101 kPa atmospheric pressure). Plants were harvested at maturity (90 days for soybean and 105 days for potato) and all tissues analyzed for proximate nutritional composition (i.e. protein, fat, carbohydrate, crude fiber, and ash content). Soybean seed ash and crude fiber were higher and carbohydrate was lower than values reported for field-grown seed. Potato tubers showed little difference from field-grown tubers. With the exception of increased crude fiber of soybean seed with increased CO2, no trends were apparent with regard to CO2 effects on proximate composition of soybean seed and potato tubers. Crude fiber of soybean stems and leaves increased with increased CO2, as did soybean leaf protein (total nitrogen). Potato leaf and stem (combined) protein levels also increased with increased CO2, while leaf and stem carbohydrates decreased. Values for leaf and stem protein and ash were higher than values generally reported for field-grown plants for both species. Results suggest that CO2 partial pressure should have little influence on proximate composition of potato tubers or soybean seed, but that high ash and protein levels might be expected from leaves and stems of crops grown in controlled environments of a CELSS.

  18. Proximate nutritional composition of CELSS crops grown at different CO2 partial pressures.

    PubMed

    Wheeler, R M; Mackowiak, C L; Sager, J C; Knott, W M; Berry, W L

    1994-11-01

    Two CELSS candidate crops, soybean (Glycine max) and potato (Solanum tuberosum), were grown hydroponically in controlled environments maintained at carbon dioxide (CO2) partial pressures ranging from 0.05 to 1.00 kPa (500 to 10,000 ppm at 101 kPa atmospheric pressure). Plants were harvested at maturity (90 days for soybean and 105 days for potato) and all tissues analyzed for proximate nutritional composition (i.e. protein, fat, carbohydrate, crude fiber, and ash content). Soybean seed ash and crude fiber were higher and carbohydrate was lower than values reported for field-grown seed. Potato tubers showed little difference from field-grown tubers. With the exception of increased crude fiber of soybean seed with increased CO2, no trends were apparent with regard to CO2 effects on proximate composition of soybean seed and potato tubers. Crude fiber of soybean stems and leaves increased with increased CO2, as did soybean leaf protein (total nitrogen). Potato leaf and stem (combined) protein levels also increased with increased CO2, while leaf and stem carbohydrates decreased. Values for leaf and stem protein and ash were higher than values generally reported for field-grown plants for both species. Results suggest that CO2 partial pressure should have little influence on proximate composition of potato tubers or soybean seed, but that high ash and protein levels might be expected from leaves and stems of crops grown in controlled environments of a CELSS. PMID:11540178

  19. The effect of incomplete acetylene washout on cardiac output measurement using open circuit acetylene uptake.

    PubMed

    Balouch, Jamal; Olfert, I Mark; Wagner, Peter D; Hopkins, Susan R

    2007-02-15

    The open circuit acetylene uptake method is a useful non-invasive means of measuring cardiac output. However, because of accumulation of inhaled acetylene in tissues, the cardiac output uptake is underestimated, if residual acetylene is not allowed to wash out completely in between measurements. We determined the effect of applying a correction factor that estimates mixed venous acetylene concentration from endtidal values to the calculation of cardiac output. This accounts for mixed venous acetylene present during measurements made before complete washout. Six healthy subjects performed steady-state exercise at approximately 30% and 60% of V(O2 max). Cardiac output measurements were made at each exercise intensity using the open circuit acetylene uptake method (inspired [acetylene] approximately 1%), with the first and last measurements having no detectible levels of acetylene in expired gas (reference measurement). Data were also obtained with immediate pre-measurement endtidal concentrations ranging from 3% to 15% of the inspired [acetylene], in random order in between. Oxygen consumption, carbon dioxide production and heart rate did not change significantly during testing at each exercise intensity. Reference cardiac output also did not change significantly and averaged 11.1+/-0.8 L/min at 30% of V(O2 max) and 16.5+/-2.0 L/min at 60% of V(O2 max). Uncorrected cardiac output measurements progressively underestimated cardiac output by 15% at the 3% of inspired endtidal [acetylene] and by over 50% at 15% [acetylene] (p<0.0001). However, when corrected for residual endtidal [acetylene], cardiac outputs were not significantly different from the reference measurements. The results of this study suggest that by accounting for residual endtidal acetylene in mixed venous blood, cardiac output can be accurately measured even when washout of acetylene is incomplete, allowing measurements as often as every 10-15 s. PMID:16714151

  20. Relating oxygen partial pressure, saturation and content: the haemoglobin–oxygen dissociation curve

    PubMed Central

    Rudenski, Aram; Gibson, John; Howard, Luke; O’Driscoll, Ronan

    2015-01-01

    Key Points In clinical practice, the level of arterial oxygenation can be measured either directly by blood gas sampling to measure partial pressure (PaO2) and percentage saturation (SaO2) or indirectly by pulse oximetry (SpO2). This review addresses the strengths and weaknesses of each of these tests and gives advice on their clinical use. The haemoglobin–oxygen dissociation curve describing the relationship between oxygen partial pressure and saturation can be modelled mathematically and routinely obtained clinical data support the accuracy of a historical equation used to describe this relationship. Educational Aims To understand how oxygen is delivered to the tissues. To understand the relationships between oxygen saturation, partial pressure, content and tissue delivery. The clinical relevance of the haemoglobin–oxygen dissociation curve will be reviewed and we will show how a mathematical model of the curve, derived in the 1960s from limited laboratory data, accurately describes the relationship between oxygen saturation and partial pressure in a large number of routinely obtained clinical samples. To understand the role of pulse oximetry in clinical practice. To understand the differences between arterial, capillary and venous blood gas samples and the role of their measurement in clinical practice. The delivery of oxygen by arterial blood to the tissues of the body has a number of critical determinants including blood oxygen concentration (content), saturation (SO2) and partial pressure, haemoglobin concentration and cardiac output, including its distribution. The haemoglobin–oxygen dissociation curve, a graphical representation of the relationship between oxygen satur­ation and oxygen partial pressure helps us to understand some of the principles underpinning this process. Historically this curve was derived from very limited data based on blood samples from small numbers of healthy subjects which were manipulated in vitro and ultimately determined

  1. Nitrogenase Activity Is Affected by Reduced Partial Pressures of N2 and NO3- 1.

    PubMed Central

    Blumenthal, J. M.; Russelle, M. P.; Vance, C. P.

    1997-01-01

    Optimal use of legumes in cropping systems requires a thorough understanding of the interaction between inorganic N nutrition and symbiotic N2 fixation. Our objective was to test the hypothesis that increased NO3- uptake by alfalfa (Medicago sativa L.) would compensate for lower N2 fixation caused by low partial pressure of N2. Root systems of hydroponically grown alfalfa at 2 mg L-1 NO3--N were exposed to (a) 80% N2, (b) 7% N2, (c) 2% N2, or (d) 0% N2. Exposure to reduced partial pressures of N2 reduced total nitrogenase activity (TNA, measured as H2 production in 20% O2 and 80% Ar) by 40% within less than 30 min, followed by a recovery period over the next 30 min to initial activity. Five hours after treatments began, the TNA of plants exposed to 7 and 2% N2 was substantially higher than pretreatment activities, whereas the TNA of plants exposed either to 0 or 80% N2 did not differ from pretreatment values. The decline in TNA due to NO3- exposure over 4 d was not affected by reduced partial pressure of N2. During the 1st h the proportion of electrons used for the reduction of N2 fell from 0.52 to 0.23 for plants exposed to 7% N2, and to 0.09 for plants exposed to 2% N2, and remained unchanged for the rest of the experiment. Although the hypothesis that alfalfa compensated with increased NO3- uptake for lower N2 fixation was not validated by our results, we unexpectedly demonstrated that the decline in TNA upon exposure to NO3- was independent of the N2-fixing efficiency (i.e. the amount of N2 reduced by nitrogenase) of the symbiosis. PMID:12223779

  2. Toxicity of elevated partial pressures of carbon dioxide to invasive New Zealand mudsnails

    USGS Publications Warehouse

    Nielson, R. Jordan; Moffitt, Christine M.; Watten, Barnaby J.

    2012-01-01

    The authors tested the efficacy of elevated partial pressures of CO2 to kill invasive New Zealand mudsnails. The New Zealand mudsnails were exposed to 100 kPa at three water temperatures, and the survival was modeled versus dose as cumulative °C-h. We estimated an LD50 of 59.4°C-h for adult and juvenile New Zealand mudsnails. The results suggest that CO2 may be an effective and inexpensive lethal tool to treat substrates, tanks, or materials infested with New Zealand mudsnails.

  3. Payload specialist Umberto Guidioni, wearing the partial pressure launch and entry garment, prepares

    NASA Technical Reports Server (NTRS)

    1996-01-01

    STS-75 ONBOARD VIEW --- Payload specialist Umberto Guidioni, wearing the partial pressure launch and entry garment, prepares for the de-orbit phase of the 16-day flight. Guidioni represents the Italian Space Agency (ASI). The seven member crew was launched aboard the Space Shuttle Columbia on February 22, 1996, and landed on March 9, 1996. Crew members were Andrew M. Allen, mission commander; Scott J. Horowitz, pilot; Franklin R. Chang-Diaz, payload commander; and Maurizio Cheli, European Space Agency (ESA); Jeffrey A. Hoffman and Claude Nicollier, (ESA), all mission specialists; along with Guidioni.

  4. Detonation engine fed by acetylene-oxygen mixture

    NASA Astrophysics Data System (ADS)

    Smirnov, N. N.; Betelin, V. B.; Nikitin, V. F.; Phylippov, Yu. G.; Koo, Jaye

    2014-11-01

    The advantages of a constant volume combustion cycle as compared to constant pressure combustion in terms of thermodynamic efficiency has focused the search for advanced propulsion on detonation engines. Detonation of acetylene mixed with oxygen in various proportions is studied using mathematical modeling. Simplified kinetics of acetylene burning includes 11 reactions with 9 components. Deflagration to detonation transition (DDT) is obtained in a cylindrical tube with a section of obstacles modeling a Shchelkin spiral; the DDT takes place in this section for a wide range of initial mixture compositions. A modified ka-omega turbulence model is used to simulate flame acceleration in the Shchelkin spiral section of the system. The results of numerical simulations were compared with experiments, which had been performed in the same size detonation chamber and turbulent spiral ring section, and with theoretical data on the Chapman-Jouguet detonation parameters.

  5. Low tritium partial pressure permeation system for mass transport measurement in lead lithium eutectic

    DOE PAGESBeta

    Pawelko, R. J.; Shimada, M.; Katayama, K.; Fukada, S.; Humrickhouse, P. W.; Terai, T.

    2015-11-28

    This paper describes a new experimental system designed to investigate tritium mass transfer properties in materials important to fusion technology. Experimental activities were carried out at the Safety and Tritium Applied Research (STAR) facility located at the Idaho National Laboratory (INL). The tritium permeation measurement system was developed as part of the Japan/US TITAN collaboration to investigate tritium mass transfer properties in liquid lead lithium eutectic (LLE) alloy. The experimental system is configured to measure tritium mass transfer properties at low tritium partial pressures. Initial tritium permeation scoping tests were conducted on a 1 mm thick α-Fe plate to determinemore » operating parameters and to validate the experimental technique. A second series of permeation tests was then conducted with the α-Fe plate covered with an approximately 8.5 mm layer of liquid lead lithium eutectic alloy (α-Fe/LLE). We present preliminary tritium permeation data for α-Fe and α-Fe/LLE at temperatures between 400 and 600°C and at tritium partial pressures between 1.7E-3 and 2.5 Pa in helium. Preliminary results for the α-Fe plate and α-Fe/LLE indicate that the data spans a transition region between the diffusion-limited regime and the surface-limited regime. In conclusion, additional data is required to determine the existence and range of a surface-limited regime.« less

  6. Low tritium partial pressure permeation system for mass transport measurement in lead lithium eutectic

    SciTech Connect

    Pawelko, R. J.; Shimada, M.; Katayama, K.; Fukada, S.; Humrickhouse, P. W.; Terai, T.

    2015-11-28

    This paper describes a new experimental system designed to investigate tritium mass transfer properties in materials important to fusion technology. Experimental activities were carried out at the Safety and Tritium Applied Research (STAR) facility located at the Idaho National Laboratory (INL). The tritium permeation measurement system was developed as part of the Japan/US TITAN collaboration to investigate tritium mass transfer properties in liquid lead lithium eutectic (LLE) alloy. The experimental system is configured to measure tritium mass transfer properties at low tritium partial pressures. Initial tritium permeation scoping tests were conducted on a 1 mm thick α-Fe plate to determine operating parameters and to validate the experimental technique. A second series of permeation tests was then conducted with the α-Fe plate covered with an approximately 8.5 mm layer of liquid lead lithium eutectic alloy (α-Fe/LLE). We present preliminary tritium permeation data for α-Fe and α-Fe/LLE at temperatures between 400 and 600°C and at tritium partial pressures between 1.7E-3 and 2.5 Pa in helium. Preliminary results for the α-Fe plate and α-Fe/LLE indicate that the data spans a transition region between the diffusion-limited regime and the surface-limited regime. In conclusion, additional data is required to determine the existence and range of a surface-limited regime.

  7. DEVELOPMENT OF PRESSURIZED CIRCULATIONG FLUIDIZED BED PARTIAL GASIFICATION MODULE(PGM)

    SciTech Connect

    Archie Robertson

    2003-04-17

    Foster Wheeler Power Group, Inc. is working under US Department of Energy contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% and produce near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines, or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The amount of syngas and char produced by the PGM can be tailored to fit the production objectives of the overall plant, i.e., power generation, clean liquid fuel production, chemicals production, etc. Hence, PGM is a robust building block that offers all the advantages of coal gasification but in a more user-friendly form; it is also fuel flexible in that it can use alternative fuels such as biomass, sewerage sludge, etc. This report describes the work performed during the January 1--March 31, 2003 time period.

  8. Deformation mechanisms in granodiorite at effective pressures to 100 MPa and temperatures to partial melting

    SciTech Connect

    Friedman, M.; Handin, J.; Bauer, S.J.

    1981-01-01

    Deformation mechanisms in room-dry and water-saturated specimens of Charcoal Granodiorite, shortened at 10/sup -4/s/sup -1/, at effective pressures (Pe) to 100 MPa and temperatures to partial melting (less than or equal to 1050/sup 0/C) are documented with a view toward providing criteria to recognize and characterize the deformation for geological and engienering applications. Above 800/sup 0/C strength decreases dramatically at effective pressures greater than or equal to 50 MPa and water-weakening reduces strength an additional 30 to 40% at Pe = 100 MPa. Strains at failure are only 0.1 to 2.2% with macroscopic ductility (within this range) increasing as the effective pressures are increased and in wet versus dry tests. Shattering (multiple faulting) gives way to faulting along a single zone to failure without macroscopic faulting as ductility increases. Microscopically, cataclasis (extension microfracturing and thermal cracking with rigid-body motions) predominates at all conditions. Dislocation gliding contributes little to the strain. Precursive extension microfractures coalesce to produce the throughgoing faults with gouge zones exhibiting possible Riedel shears. Incipient melting, particularly in wet tests, produces a distinctive texture along feldspar grain boundaries that suggests a grain-boundary-softening effect contributes to the weakening. In addition, it is demonstrated that the presence of water does not lead to more microfractures, but to a reduction in the stresses required to initiate and propagate them.

  9. Partial Melting in the Iron-Sulfur System at High Pressures

    NASA Astrophysics Data System (ADS)

    Campbell, A. J.; Seagle, C. T.; Heinz, D. L.; Shen, G.; Prakapenka, V. B.

    2005-12-01

    Melting in the Fe-rich portion of the Fe-S system was investigated to pressures of 80 GPa, using in situ synchrotron x-ray diffraction through a laser-heated diamond anvil cell at the GSECARS sector of APS. Intimately mixed Fe-FeS powders were compressed between insulating layers of NaCl in the diamond anvil cell. Double-sided laser heating was used to reduce axial temperature gradients, and temperatures were measured spectroradiometrically on both sides of the cell. Only the central, hottest part of the laser-heated region was probed with the 5x7 micron x-ray beam. At high pressures, Fe3S was formed by reaction between Fe and FeS upon laser heating, with excess Fe remaining. The Fe was used as an internal, high-temperature pressure standard based on existing equation of state data. Diffraction data were collected during laser heating and also from the quenched sample following each heating episode. The use of an image plate area detector greatly improved our ability to verify the presence of both metal and sulfide during heating. The eutectic temperature was bracketed by the absence of one phase above the melting point and the presence of both phases at lower temperature. The reappearance of the absent component (sulfide or metal) upon rapid quenching was taken as confirmation that partial melting had been achieved. Our results using this method are in broad agreement with earlier data that were based on textural criteria.

  10. The role of hydrogen partial pressure on the annealing of copper substrates for graphene CVD synthesis

    NASA Astrophysics Data System (ADS)

    Ramos, Welyson T. S.; Cunha, Thiago H. R.; Barcelos, Ingrid D.; Miquita, Douglas R.; Ferrari, Gustavo A.; de Oliveira, Sergio; Seara, Luciana M.; Silva Neto, Eliel G.; Ferlauto, Andre S.; Lacerda, Rodrigo G.

    2016-04-01

    The influence of hydrogen utilized during the thermal treatment of copper substrates on the subsequent graphene growth is investigated. It is known that various parameters such as nature of the carbon precursor, temperature and pressure strongly affect the quality of the graphene grown by chemical vapor deposition. Another important parameter is the hydrogen partial pressure adjusted during the growth stage and in the pre-growth annealing of the substrate. In attempts to elucidate the role of hydrogen assisted thermal annealing on the copper substrate morphology and on the subsequent graphene growth, we subjected Cu foils to thermal annealing under H2 atmosphere at different pressures. The copper surface was characterized by scanning electronic microscopy (SEM) and atomic force microscopy whereas graphene films and grains were characterized by Raman spectroscopy and SEM. Our findings suggest that hydrogen not only affect the Cu surface but also diffuses into the substrate, being stored in the bulk material during the thermal treatment of the substrate. The release of hydrogen species in the subsequent stages of growth can result in damage to the graphene layer or induce the nucleation of additional layers depending on the growth and pre-growth conditions. Therefore, the use of hydrogen during the annealing of ‘low purity Cu foils’ should be carefully planned in order to obtain high quality graphene via LPCVD.

  11. Partial melting, fluid supercriticality and element mobility in ultrahigh-pressure metamorphic rocks during continental collision

    NASA Astrophysics Data System (ADS)

    Zheng, Yong-Fei; Xia, Qiong-Xia; Chen, Ren-Xu; Gao, Xiao-Ying

    2011-08-01

    Partial melting at continental lithosphere depths plays an important role in generating geochemical variations in igneous rocks. In particular, dehydration melting of ultrahigh-pressure (UHP) metamorphic rocks during continental collision provides a petrological link to intracrustal differentiation with respect to the compositional evolution of continental crust. While island arc magmatism represents one end-member of fluid-induced large-scale melting in the mantle wedge during subduction of the oceanic crust, the partial melting of UHP rocks can be viewed as the other end-member of fluid-induced small-scale anatexis during exhumation of the deeply subducted continental crust. This latter type of melting is also triggered by metamorphic dehydration in response to P-T changes during the continental collision. It results in local occurrences of hydrous melts (even supercritical fluids) as felsic veinlets between boundaries of and multiphase solid inclusions in UHP metamorphic minerals as well as local accumulation of veinlet-like felsic leucosomes in foliated UHP metamorphic rocks and metamorphically grown zircons in orogenic peridotites. Thus, very low-degree melts of UHP rocks provide a window into magmatic processes that operated in continental subduction zones. This article presents a review on available results from experimental petrology concerning the possibility of partial melting under conditions of continental subduction-zone metamorphism, and petrological evidence for the occurrence of dehydration-driven in-situ partial melting in natural UHP rocks during the continental collision. Although the deeply subducted continental crust is characterized by a relative lack of aqueous fluids, the partial melting in UHP rocks commonly takes place during decompression exhumation to result in local in-situ occurrences of felsic melts at small scales. This is caused by the local accumulation of aqueous fluids due to the breakdown of hydrous minerals and the exsolution

  12. Squeeze Film Problems of Long Partial Journal Bearings for Non-Newtonian Couple Stress Fluids with Pressure-Dependent Viscosity

    NASA Astrophysics Data System (ADS)

    Lin, Jaw-Ren; Chu, Li-Ming; Hung, Chi-Ren; Lu, Rong-Fang

    2011-09-01

    According to the experimental work of C. Barus in Am. J. Sci. 45, 87 (1893) [1], the dependency of liquid viscosity on pressure is exponential. Therefore, we extend the study of squeeze film problems of long partial journal bearings for Stokes non-Newtonian couple stress fluids by considering the pressure-dependent viscosity in the present paper. Through a small perturbation technique, we derive a first-order closed-form solution for the film pressure, the load capacity, and the response time of partial-bearing squeeze films. It is also found that the non-Newtonian couple-stress partial bearings with pressure-dependent viscosity provide better squeeze-film characteristics than those of the bearing with constant-viscosity situation.

  13. Partial Pressures for Several In-Se Compositions from Optical Absorbance of the Vapor

    NASA Technical Reports Server (NTRS)

    Brebrick, R. F.; Su, Ching-Hua

    2001-01-01

    The optical absorbance of the vapor phase over various In-Se compositions between 33.3-60.99 at.% Se and 673-1418 K was measured and used to obtain the partial pressures of Se2(g) and In2Se(g). The results are in agreement with silica Bourdon gauge measurements for compositions between 50-61 at.%, but significantly higher than those from Knudsen cell and simultaneous Knudsen-torsion cell measurements. It is found that 60.99 at.% Se lies outside the sesquiselenide homogeneity range and 59.98 at.% Se lies inside and is the congruently melting composition. The Gibbs energy of formation of the liquid from its pure liquid elements between 1000-1300 K is essentially independent of temperature and falls between -36 to -38 kJ per g atomic weight for 50 and 56% Se at 1200 and 1300 K.

  14. Partial Pressures of In-Se from Optical Absorbance of the Vapor

    NASA Technical Reports Server (NTRS)

    Brebrick, R. F.; Su, Ching-Hua; Curreri, Peter A. (Technical Monitor)

    2001-01-01

    The optical absorbance of the vapor phase over various In-Se compositions between 33.3 and 61 atomic percent and 673 and 1418K has been measured and used to obtain the partial pressures of Se2(g) and In2Se(g). The results are in agreement with silica Bourdon gage measurements for compositions between 50 and 61 atomic percent but significantly higher than those from Knudsen cell and simultaneous Torsion-Knudsen cell measurements. The sequiselenide is found to sublime incongruently. Congruent vaporization occurs for the liquid above 1000 K between 50.08 and 56 at. percent Se. The Gibbs energy of formation of the liquid from its pure liquid elements between 1000 and 1300K is essentially independent of temperature and falls between -36 and -38 kJ per gram atomic weight for 50 and 56 percent Se at 1200 and 1300K.

  15. Physical Mechanisms of Failure, Ultralow Partial Pressure Lubrication, and the Reservoir Effect in MEMS

    NASA Astrophysics Data System (ADS)

    Hook, David Adam

    The aim of this work is to examine the effectiveness of self-assembled monolayer (SAM) coatings as long term lubrication coatings in microsystems, to examine the failure regimes of SAM coated devices, to examine the role of mobility in adsorbed lubricating films, and to examine evolution of the coefficient of friction of devices surrounded by ultralow partial pressures of alcohols up to saturation. Finally the role of self assembled monlayers in vapor phase lubrication is examined. Self-assembled monolayers are ubiquitous in fabrication of free-standing microdevices because of their ability to prevent release related and dormancy related stiction. However their ability to lubricate under sliding and normal contact conditions is not well documented. It can be shown that the energy dissipated per unit area in one sliding cycle due to friction is significant under general loading conditions. Therefore from an energy dissipated standpoint the bond energies of the silane molecules should not be enough to withstand even a short number of cycles. An extension of this is the energy imparted to the surface through a normal loading cycle through a loss of kinetic energy. It can also be shown that this is enough to break the silicon oxygen bonds however this is over a longer time scale than in sliding. Also there is an open question on the role of mobile and non-mobile adsorbed species on friction. Is the mobility of a molecule/layer on a surface an indicator of the effectiveness of the lubrication potential of the layer? Do submonolayer coverages of alcohols "lock-up" to contacting surfaces by disrupting non-corrogated potentials? Is there a distinct lowering of frictional forces at the formation of a monolayer? Controlled adsorption of mobile and non-mobile species on rubbing contacts is necessary to elucidate this physical relationship. To accomplish this one must take into account that friction measurements are highly scale dependant. Therefore to ensure the accuracy of

  16. Diurnal changes in the partial pressure of carbon dioxide in coral reef waters

    SciTech Connect

    Kayanne, Hajime; Suzuki, Atsushi; Saito, Hiroshi

    1995-07-14

    Coral reefs are considered to be a source of atmospheric carbon dioxide because of their high calcium carbonate production and low net primary production. This was tested by direct measurement of diurnal changes in the partial pressure of carbon dioxide (P{sub CO2}) in reef waters during two 3-day periods, one in March 1993 and one in March 1994, on Shiraho reef of the Ryukyu Islands, Japan. Although the P{sub CO2} values in reef waters exhibited large diurnal changes ranging from 160 to 520 microatmospheres, they indicate that the reef flat area is a net sink for atmospheric carbon dioxide. This suggests that the net organic production rate of the reef community exceeded its calcium carbonate production rate during the observation periods. 16 refs., 2 figs., 1 tab.

  17. Instrument for stable high temperature Seebeck coefficient and resistivity measurements under controlled oxygen partial pressure

    SciTech Connect

    Ihlefeld, Jon F.; Brown-Shaklee, Harlan James; Sharma, Peter Anand

    2015-04-28

    The transport properties of ceramic materials strongly depend on oxygen activity, which is tuned by changing the partial oxygen pressure (pO2) prior to and during measurement. Within, we describe an instrument for highly stable measurements of Seebeck coefficient and electrical resistivity at temperatures up to 1300 K with controlled oxygen partial pressure. An all platinum construction is used to avoid potential materials instabilities that can cause measurement drift. Two independent heaters are employed to establish a small temperature gradient for Seebeck measurements, while keeping the average temperature constant and avoiding errors associated with pO2-induced drifts in thermocouple readings. Oxygen equilibrium is monitored using both an O2 sensor and the transient behavior of the resistance as a proxy. A pO2 range of 10-25–100 atm can be established with appropriate gas mixtures. Seebeck measurements were calibrated against a high purity platinum wire, Pt/Pt–Rh thermocouple wire, and a Bi2Te3 Seebeck coefficient Standard Reference Material. To demonstrate the utility of this instrument for oxide materials we present measurements as a function of pO2 on a 1 % Nb-doped SrTiO3 single crystal, and show systematic changes in properties consistent with oxygen vacancy defect chemistry. Thus, an approximately 11% increase in power factor over a pO2 range of 10-19–10-8 atm at 973 K for the donor-doped single crystals is observed.

  18. Instrument for stable high temperature Seebeck coefficient and resistivity measurements under controlled oxygen partial pressure

    DOE PAGESBeta

    Ihlefeld, Jon F.; Brown-Shaklee, Harlan James; Sharma, Peter Anand

    2015-04-28

    The transport properties of ceramic materials strongly depend on oxygen activity, which is tuned by changing the partial oxygen pressure (pO2) prior to and during measurement. Within, we describe an instrument for highly stable measurements of Seebeck coefficient and electrical resistivity at temperatures up to 1300 K with controlled oxygen partial pressure. An all platinum construction is used to avoid potential materials instabilities that can cause measurement drift. Two independent heaters are employed to establish a small temperature gradient for Seebeck measurements, while keeping the average temperature constant and avoiding errors associated with pO2-induced drifts in thermocouple readings. Oxygen equilibriummore » is monitored using both an O2 sensor and the transient behavior of the resistance as a proxy. A pO2 range of 10-25–100 atm can be established with appropriate gas mixtures. Seebeck measurements were calibrated against a high purity platinum wire, Pt/Pt–Rh thermocouple wire, and a Bi2Te3 Seebeck coefficient Standard Reference Material. To demonstrate the utility of this instrument for oxide materials we present measurements as a function of pO2 on a 1 % Nb-doped SrTiO3 single crystal, and show systematic changes in properties consistent with oxygen vacancy defect chemistry. Thus, an approximately 11% increase in power factor over a pO2 range of 10-19–10-8 atm at 973 K for the donor-doped single crystals is observed.« less

  19. Modeling the exhumation path of partially melted ultrahigh-pressure metapelites, North-East Greenland Caledonides

    NASA Astrophysics Data System (ADS)

    Lang, Helen M.; Gilotti, Jane A.

    2015-06-01

    Pseudosection modeling constrains the pressure-temperature (P-T) exhumation path of partially melted ultrahigh-pressure (UHP) metapelites exposed in the North-East Greenland UHP terrane. A robust peak P and T estimate of 3.6 GPa and 970 °C based on mineral assemblages in nearby kyanite eclogites is the starting point for the P-T path. Although the peak assemblage for the metapelite is not preserved, the calculated modeled peak assemblage contained substantial clinopyroxene, garnet, phengite, K-feldspar and coesite with minor kyanite and rutile. Combining the pseudosection and observed textures, the decompression path crosses the coesite-quartz transition before reaching the dry phengite dehydration melting reaction where phengite is abruptly consumed. In the range of 2.5 to 2.2 GPa, clinopyroxene is completely consumed and garnet grows to its maximum volume and grossular content, matching the high grossular rims of relict megacrysts. Plagioclase joins the assemblage and the pseudosection predicts up to 12-13 vol.% melt in the supersolidus assemblage, which contained garnet, liquid, K-feldspar, plagioclase, kyanite, quartz and rutile. At this stage, the steep decompression path flattened out and became nearly isobaric. The melt crystallization assemblage that formed when the path crossed the solidus with decreasing temperature contains phengite, garnet, biotite, 2 feldspars, kyanite, quartz and rutile. Therefore, the path must have intersected the solidus at approximately 1.2 GPa, 825 °C. The pseudosection predicts that garnet is consumed on the cooling path, but little evidence of late garnet consumption or other retrograde effects is observed. This may be due to partial melt loss from the rock. Isochemical PT-n and PT-X sections calculated along the P-T path display changes in mineral assemblage and composition that are consistent with preserved assemblages.

  20. Kinetics and Structure of Superagglomerates Produced by Silane and Acetylene

    NASA Technical Reports Server (NTRS)

    Mulholland, G. W.; Hamins, A.; Sivathanu, Y.

    1999-01-01

    The evolution of smoke in a laminar diffusion flame involves several steps. The first step is particle inception/nucleation in the high-temperature fuel-rich region of the flame followed by surface growth and coagulation/coalescence of the small particles. As the primary spheres grow in size and lose hydrogen, the colliding particles no longer coalesce but retain their identity as a cluster of primary spheres, termed an agglomerate. Finally, in the upper portion of the flame, the particles enter an oxidizing environment which may lead to partial or complete burnout of the agglomerates. Currently there is no quantitative model for describing the growth of smoke agglomerates up to superagglomerates with an overall dimension of 10 microns and greater. Such particles are produced during the burning of acetylene and fuels containing benzene rings such as toluene and polystyrene. In the case of polystyrene, smoke agglomerates in excess of 1 mm have been observed "raining" out from large fires. Evidence of the formation of superagglomerates in a laminar acetylene/air diffusion flame has been recently reported. Acetylene was chosen as the fuel since the particulate loading in acetylene/air diffusion flames is very high. Photographs were obtained by Sorensen using a microsecond xenon lamp of the "stream" of soot just above the flame. For low flow rates of acetylene, only submicrometer soot clusters are produced and they give rise to the homogeneous appearance of the soot stream. When the flow rate is increased to 1.7 cu cm/s, soot clusters up to 10 microns are formed and they are responsible for the graininess and at a flow rate of 3.4 cu cm/s, a web of interconnected clusters as large as the width of the flame is seen. This interconnecting web of superagglomerates is described as a gel state by Sorensen et al (1998). This is the first observation of a gel for a gas phase system. It was observed that this gel state immediately breaks up into agglomerates due to buoyancy

  1. Real-time visualization of oxygen partial pressures in straight channels of running polymer electrolyte fuel cell with water plugging

    NASA Astrophysics Data System (ADS)

    Nagase, Katsuya; Suga, Takeo; Nagumo, Yuzo; Uchida, Makoto; Inukai, Junji; Nishide, Hiroyuki; Watanabe, Masahiro

    2015-01-01

    Visualization inside polymer electrolyte fuel cells (PEFCs) for elucidating the reaction distributions is expected to improve the performance, durability, and stability. An oxygen-sensitive film of a luminescent porphyrin was used to visualize the oxygen partial pressures in five straight gas-flow channels of a running PEFC with liquid-water blockages formed at the end of the channels. The blockage greatly lowered and unstabilized the cell voltage. The oxygen partial pressure decreased nearly to 0 kPa in the blocked channel. With a water blockage in a channel, the oxygen partial pressures in the adjacent channels were lowered due to an extra demand of oxygen consumption. When the number of the blocked channels increased, the oxygen partial pressure in the unblocked channels became much lowered. When the water blockages disappeared, the oxygen partial pressures quickly returned to the values before plugging. The influence of the cross flows of air through the gas diffusion layers in straight channels was much smaller than that in serpentine flow channels.

  2. Oxidation of SiC/BN/SiC Composites in Reduced Oxygen Partial Pressures

    NASA Technical Reports Server (NTRS)

    Opila, Elizabeth J.; Boyd, Meredith

    2010-01-01

    SiC fiber-reinforced SiC composites with a BN interphase are proposed for use as leading edge structures of hypersonic vehicles. The durability of these materials under hypersonic flight conditions is therefore of interest. Thermogravimetric analysis was used to characterize the oxidation kinetics of both the constituent fibers and composite coupons at four temperatures: 816, 1149, 1343, and 1538 C (1500, 2100, 2450, and 2800 F) and in oxygen partial pressures between 5% and 0.1% (balance argon) at 1 atm total pressure. One edge of the coupons was ground off so the effects of oxygen ingress into the composite could be monitored by post-test SEM and EDS. Additional characterization of the oxidation products was conducted by XPS and TOF-SIMS. Under most conditions, the BN oxidized rapidly, leading to the formation of borosilicate glass. Rapid initial oxidation followed by volatilization of boria lead to protective oxide formation and further oxidation was slow. At 1538C in 5% oxygen, both the fibers and coupons exhibited borosilicate glass formation and bubbling. At 1538C in 0.1% oxygen, active oxidation of both the fibers and the composites was observed leading to rapid SiC degradation. BN oxidation at 1538C in 0.1% oxygen was not significant.

  3. Feasibility of measuring dissolved carbon dioxide based on head space partial pressures

    USGS Publications Warehouse

    Watten, B.J.; Boyd, C.E.; Schwartz, M.F.; Summerfelt, S.T.; Brazil, B.L.

    2004-01-01

    We describe an instrument prototype that measures dissolved carbon dioxide (DC) without need for standard wetted probe membranes or titration. DC is calculated using Henry's Law, water temperature, and the steady-state partial pressure of carbon dioxide that develops within the instrument's vertical gas-liquid contacting chamber. Gas-phase partial pressures were determined with either an infrared detector (ID) or by measuring voltage developed by a pH electrode immersed in an isolated sodium carbonate solution (SC) sparged with recirculated head space gas. Calculated DC concentrations were compared with those obtained by titration over a range of DC (2, 4, 8, 12, 16, 20, 24, and 28mg/l), total alkalinity (35, 120, and 250mg/l as CaCO3), total dissolved gas pressure (-178 to 120 mmHg), and dissolved oxygen concentrations (7, 14, and 18 mg/l). Statistically significant (P < 0.001) correlations were established between head space (ID) and titrimetrically determined DC concentrations (R2 = 0.987-0.999, N = 96). Millivolt and titrimetric values from the SC solution tests were also correlated (P < 0.001, R 2 = 0.997, N = 16). The absolute and relative error associated with the use of the ID and SC solution averaged 0.9mg/l DC and 7.0% and 0.6 mg/l DC and 9.6%, respectively. The precision of DC estimates established in a second test series was good; coefficients of variation (100(SD/mean)) for the head space (ID) and titration analyses were 0.99% and 1.7%. Precision of the SC solution method was 1.3%. In a third test series, a single ID was coupled with four replicate head space units so as to permit sequential monitoring (15 min intervals) of a common water source. Here, appropriate gas samples were secured using a series of solenoid valves (1.6 mm bore) activated by a time-based controller. This system configuration reduced the capital cost per sample site from US$ 2695 to 876. Absolute error averaged 2.9, 3.1, 3.7, and 2.7 mg/ l for replicates 1-4 (N = 36) during a 21

  4. Frequency Comb-Referenced Spectroscopy in the ν1 + ν3 Region of Acetylene

    NASA Astrophysics Data System (ADS)

    Cich, Matthew J.; Forthomme, Damien; Hall, Gregory E.; Mcraven, Christopher P.; Sears, Trevor J.; Twagirayezu, Sylvestre

    2014-06-01

    class="MsoNormal">By using saturation dip absorption spectroscopy with an extended cavity diode laser locked to a frequency comb, we have measured the rest frequencies of transitions in the ν4 = 1 and ν5 = 1 hot bands in the ν1 + ν3 combination band of acetylene. The measured line frequencies are accurate to approximately 20 kHz i.e. approximately one part in 1011. Positions of the hot-band lines quoted in the HITRAN database, which are derived from the analysis of high-resolution FTIR spectra, are of the order of 10's of MHz in error. These measurements were undertaken because pressure broadened lineshape measurements of rotational lines in the combination band indicated that weak underlying hot band features were not correctly accounted for on the basis of their previously reported positions. As a result, measured line profiles in the band could not be accurately fit leading to errors of up to 1% in acetylene concentrations derived from the measurements. In addition, the pressure broadened P(11) line in the ν1 + ν3 combination band has been studied as a function of varying concentration of the absorber in nitrogen. Mixture concentrations of 1, 5 and 10% at 296 K and pressures between a few Torr and one atmosphere were made and the measurements analyzed using two different speeddependent broadening models. These experiments are designed to test the additivity of contributions to pressure broadening and shift in speed-dependent line-shape modeling, i.e. whether the lineshape parameters follow partial pressure weighting in the binary mixtures. P(11) is relatively isolated with respect to underlying hot band transitions and neighboring transitions of the same band, but it was found that the accurate positions of underlying hot-band transitions were crucial to the successful modeling of the observed line shapes, even though these lines are typically 100-1000 times weaker than P(11) itself and are many Doppler line widths removed from the line center

  5. Structural and electrical properties of pure and Cu doped NiO films deposited at various oxygen partial pressures

    NASA Astrophysics Data System (ADS)

    Reddy, Y. Ashok Kumar; Reddy, A. Mallikarjuna; Reddy, A. Sivasankar; Reddy, P. Sreedhara

    2013-02-01

    Pure and Cu doped NiO thin films were successfully deposited by dc reactive magnetron sputtering technique at various oxygen partial pressures in the range 9 × 10-5 to 6 × 10-4 mbar. It was observed that oxygen partial pressure influence the structural and electrical properties. All the deposited films were polycrystalline and exhibited cubic structure with preferential growth along (220) plane for NiO films and (111) and (220) planes for Cu doped NiO films. All the deposited films exhibited p-type conductivity. The electrical resistivity decreased from 62.24 to 9.94 Ω cm and the mobility and carrier concentration were increased with oxygen partial pressure.

  6. Pressure dependence of the electro-optic response function in partially exposed polymer dispersed ferroelectric liquid crystals

    NASA Technical Reports Server (NTRS)

    Parmar, D. S.; Holmes, H. K.

    1993-01-01

    Ferroelectric liquid crystals in a new configuration, termed partially exposed polymer dispersed ferroelectric liquid crystal (PEPDFLC), respond to external pressures and demonstrate pressure-induced electro-optic switching response. When the PEPDFLC thin film is sandwiched between two transparent conducting electrodes, one a glass plate and the other a flexible sheet such as polyvenylidene fluoride, the switching characteristics of the thin film are a function of the pressure applied to the flexible transparent electrode and the bias voltage across the electrodes. Response time measurements reveal a linear dependence of the change in electric field with external pressure.

  7. Stigmatically focusing partial pressure analyzer with dual chamber ion source. Ph.D. Thesis - Technical Univ. of Munich, 1971

    NASA Technical Reports Server (NTRS)

    Rasskopf, Klaus F.

    1987-01-01

    The partial pressure analyzer developed has a high absolute sensitivity and high resolution. Interaction effects, as they occur in conventional partial pressure analyzers between the heating filament for the emission of electrons and the residual gas, are suppressed by removing the heating filament from the measurement area. The electron beam is generated in an auxiliary vacuum compartment, and passes subsequently through an aperture into the ionization compartment. The probability is small, therefore, that the presence of substances produced at the heating filament by chemical reactions and thermal decompositions will have disturbing effects. The high sensitivity and resolution of the instrument are obtained with the aid of an electron path configuration of unconventional characteristics.

  8. Thermal expansion measurement of (U,Pu)O2-x in oxygen partial pressure-controlled atmosphere

    NASA Astrophysics Data System (ADS)

    Kato, Masato; Ikusawa, Yoshihisa; Sunaoshi, Takeo; Nelson, Andrew T.; McClellan, Kenneth J.

    2016-02-01

    Thermal expansion of U0.7Pu0.3O2-x (x = 0, 0.01, 0.02, 0.03) and U0.52Pu0.48O2.00 was investigated by a unique dilatometry which measured in an oxygen partial pressure-controlled atmosphere. The oxygen partial pressure was controlled to hold a constant oxygen-to-metal ratio in the (U,Pu)O2-x during the measurement. Thermal expansion slightly increased with the decrease in oxygen-to-metal ratio. We proposed a relationship to describe thermal expansion as a function of temperature, O/M and Pu content.

  9. Effect of Oxygen Partial Pressure on the Cyclic Oxidation Behavior of Mo76Si14B10

    NASA Astrophysics Data System (ADS)

    Roy, Barna; Khushboo; Das, Jayanta; Mitra, Rahul; Roy, Sanat Kumar

    2013-07-01

    Hot-pressed and arc-melted Mo76Si14B10 (at. pct) exhibits α-Mo solid solution, Mo3Si, and Mo5SiB2 in microstructures with varying morphologies. Cyclic oxidation tests performed at oxygen partial pressures of 0.21 and 1 atm show the mass loss of the hot-pressed alloy to be ≈1.5 and ≈4 times less, respectively, than that of the arc-melted alloy. The thickness of the protective silicate layer increases with an increase of both Moss grain size and oxygen partial pressure in the environment.

  10. Phase diagram in the (Bi,Pb)SrCaCuO system: influence of partial constraint oxygen pressure

    NASA Astrophysics Data System (ADS)

    Mansori, M.; Satre, P.; Roubin, M.; Vacquier, G.; Strobel, P.; Sebaoun, A.

    1994-12-01

    DTA-DTG, X ray diffraction and metallographic measurements at different temperatures and partial oxygen pressure in the isoplethic cut “(Bi,Pb) 2Sr 2CuO xCaCuO 2”, were carried out to analyze the influence of partial constraint oxygen pressure on phase transformations. An isobaric invariant equilibrium has been found in the P o2 range 0.5-1. Supplementary phase appearing at invariant equilibrium is (Sr,Ca) 3Cu 5O y. That phase fixes oxygen and then the weight loss is stopped.

  11. Partial Defect Verification of the Pressurized Water Reactor Spent Fuel Assemblies

    SciTech Connect

    Ham, Y S; Sitaraman, S

    2010-02-05

    The International Atomic Energy Agency (IAEA) has the responsibility to carry out independent inspections of all nuclear material and facilities subject to safeguards agreements in order to verify compliance with non-proliferation commitments. New technologies have been continuously explored by the IAEA and Member States to improve the verification measures to account for declared inventory of nuclear material and detect clandestine diversion and production of nuclear materials. Even with these efforts, a technical safeguards challenge has remained for decades for the case of developing a method in identifying possible diversion of nuclear fuel pins from the Light Water Reactor (LWR) spent fuel assemblies. We had embarked on this challenging task and successfully developed a novel methodology in detecting partial removal of fuel from pressurized water reactor spent fuel assemblies. The methodology uses multiple tiny neutron and gamma detectors in the form of a cluster and a high precision driving system to obtain underwater radiation measurements inside a Pressurized Water Reactor (PWR) spent fuel assembly without any movement of the fuel. The data obtained in such a manner can provide spatial distribution of neutron and gamma flux within a spent fuel assembly. The combined information of gamma and neutron signature is used to produce base signatures and they are principally dependent on the geometry of the detector locations, and exhibit little sensitivity to initial enrichment, burn-up or cooling time. A small variation in the fuel bundle such as a few missing pins changes the shape of the signature to enable detection. This resulted in a breakthrough method which can be used to detect pin diversion without relying on the nuclear power plant operator's declared operation data. Presented are the results of various Monte Carlo simulation studies and experiments from actual commercial PWR spent fuel assemblies.

  12. Applying Chemical Potential and Partial Pressure Concepts to Understand the Spontaneous Mixing of Helium and Air in a Helium-Inflated Balloon

    ERIC Educational Resources Information Center

    Jee-Yon Lee; Hee-Soo Yoo; Jong Sook Park; Kwang-Jin Hwang; Jin Seog Kim

    2005-01-01

    The spontaneous mixing of helium and air in a helium-inflated balloon is described in an experiment in which the partial pressure of the gases in the balloon are determined from the mole factions and the total pressure measured in the balloon. The results described provide a model for teaching concepts of partial pressure, chemical potential, and…

  13. 49 CFR 178.60 - Specification 8AL steel cylinders with porous fillings for acetylene.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Specification 8AL steel cylinders with porous...) SPECIFICATIONS FOR PACKAGINGS Specifications for Cylinders § 178.60 Specification 8AL steel cylinders with porous fillings for acetylene. (a) Type and service pressure. A DOT 8AL cylinder is a seamless steel cylinder...

  14. 49 CFR 178.60 - Specification 8AL steel cylinders with porous fillings for acetylene.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Specification 8AL steel cylinders with porous...) SPECIFICATIONS FOR PACKAGINGS Specifications for Cylinders § 178.60 Specification 8AL steel cylinders with porous fillings for acetylene. (a) Type and service pressure. A DOT 8AL cylinder is a seamless steel cylinder...

  15. 49 CFR 178.60 - Specification 8AL steel cylinders with porous fillings for acetylene.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Specification 8AL steel cylinders with porous...) SPECIFICATIONS FOR PACKAGINGS Specifications for Cylinders § 178.60 Specification 8AL steel cylinders with porous fillings for acetylene. (a) Type and service pressure. A DOT 8AL cylinder is a seamless steel cylinder...

  16. Pulsed erbium fiber laser with an acetylene-filled photonic crystal fiber for saturable absorption.

    PubMed

    Marty, Patrick Thomas; Morel, Jacques; Feurer, Thomas

    2011-09-15

    We investigate the dynamics of an erbium-doped fiber ring laser that is equipped with an intracavity hollow core photonic crystal fiber gas cell. The cell is filled with acetylene as a saturable absorber. We observe cw operation at low pressures, Q switching at intermediate pressure levels, and mode locking at high pressures applied. Moreover, we show that the transition from the cw to the pulsed mode may be exploited for sensitive gas detection. PMID:21931393

  17. Crystalline structure of ceria particles controlled by the oxygen partial pressure and STI CMP performances.

    PubMed

    Kim, Ye-Hwan; Kim, Sang-Kyun; Kim, Namsoo; Park, Jea-Gun; Paik, Ungyu

    2008-09-01

    The effect of the crystalline structures of nano-sized ceria particles on shallow trench isolation (STI) chemical mechanical planarization (CMP) performance was investigated. The ceria particles were synthesized via a solid-state displacement reaction method, and their crystalline structure was controlled by regulating the oxygen partial pressure at the reaction site on the precursor. The crystalline structures of ceria particles were analyzed by the high-resolution TEM nano-beam diffraction pattern. In a calcination process with a high oxygen concentration, the synthesized ceria particles had a cubic fluorite structure (CeO(2)), because of the decarbonation of the cerium precursor. However, a low oxygen concentration results in a hexagonal phase cerium oxide (Ce(2)O(3)) rather than the cubic phase due to the insufficient oxidation of Ce(3+) to Ce(4+). In the STI CMP evaluation, the ceria slurry prepared with the cubic CeO(2) shows enhanced performances of the oxide-to-nitride removal selectivity. PMID:18562111

  18. Effects of varying oxygen partial pressure on molten silicon-ceramic substrate interactions

    NASA Technical Reports Server (NTRS)

    Ownby, D. P.; Barsoum, M. W.

    1980-01-01

    The silicon sessile drop contact angle was measured on hot pressed silicon nitride, silicon nitride coated on hot pressed silicon nitride, silicon carbon coated on graphite, and on Sialon to determine the degree to which silicon wets these substances. The post-sessile drop experiment samples were sectioned and photomicrographs were taken of the silicon-substrate interface to observe the degree of surface dissolution and degradation. Of these materials, silicon did not form a true sessile drop on the SiC on graphite due to infiltration of the silicon through the SiC coating, nor on the Sialon due to the formation of a more-or-less rigid coating on the liquid silicon. The most wetting was obtained on the coated Si3N4 with a value of 42 deg. The oxygen concentrations in a silicon ribbon furnace and in a sessile drop furnace were measured using the protable thoria-yttria solid solution electrolyte oxygen sensor. Oxygen partial pressures of 10 to the minus 7 power atm and 10 to the minus 8 power atm were obtained at the two facilities. These measurements are believed to represent nonequilibrium conditions.

  19. [The influence of low partial oxygen pressure on the biolodical process of mesenchymal stromal cells].

    PubMed

    Berezovskyĭ, V Ia; Plotnikova, L M; Vesel'skyĭ, S P; Litovka, I H

    2014-01-01

    The influence of low partial oxygen pressure (Po2) on the amino acid composition in culture medium of human mesenchymal stromal cell (MSC) lines 4BL has been studied. At 23 mm Hg (3% oxygen), a significant decrease (by 31%) in the concentration of proline and hydroxyproline was registered. Under these conditions, the concentration of serine and aspartic acid decreased by 45% compared to the control. Maximum consumption of free amino acids from the culture medium required for the synthesis of collagen (proline and hydroxyproline by 42%, serine and aspartic acid by 62%) was observed at a gas-phase Po2 of 38 mm Hg (5% O2). At Po2 76 mm Hg (10% O2), a lack of amino acids proline and hydroxyproline was only 21%, while that of glutamine and alanine amounted 12% compared to the control. This intensity ratio of consumption of amino acids may indicate that the maximum of MSC vital functions occurs at Po2 38 mm Hg. PMID:25095672

  20. Fiber-optic fluorescence-quenching oxygen partial pressure sensor using platinum octaethylporphyrin.

    PubMed

    Davenport, John J; Hickey, Michelle; Phillips, Justin P; Kyriacou, Panayiotis A

    2016-07-20

    The development and bench testing of a fiber-optic oxygen sensor is described. The sensor is designed for measurement of tissue oxygen levels in the mucosa of the digestive tract. The materials and construction are optimized for insertion through the mouth for measurement in the lower esophagus. An oxygen-sensitive fluorescence-quenching film was applied as a solution of platinum octaethylporphyrin (PtOEP) poly(ethyl methacrylate) (PEMA) and dichloromethane and dip coated onto the distal tip of the fiber. The sensor was tested by comparing relative fluorescence when immersed in liquid water at 37°C, at a range of partial pressures (0-101 kPa). Maximum relative fluorescence at most oxygen concentrations was seen when the PtOEP concentration was 0.1  g.L-1, four layers of coating solution were applied, and a fiber core radius of 600 μm was selected, giving a Stern-Volmer constant of 0.129  kPa-1. The performance of the sensor is suitable for many in vivo applications, particularly mucosal measurements. It has sufficient sensitivity, is sterilizable, and is sufficiently flexible and robust for insertion via the mouth without damage to the probe or risk of harm to the patient. PMID:27463913

  1. Spectroscopic study of partially-ordered semiconductor heterojunction under high pressure and high magnetic field

    SciTech Connect

    Yu, P.Y.; Martinez, G.; Zeman, J.; Uchida, K.

    2000-12-31

    Photoluminescence upconversion (PLU) is a phenomenon in which a sample emits photons with energy higher than that of the excitation photon. This effect has been observed in many materials including rare earth ions doped in insulating hosts and semiconductor heterostructures without using high power lasers as the excitation source. Recently, this effect has been observed also in partially CuPt-ordered GaInP{sub 2} epilayers grown on GaAs substrates. As a spectroscopic technique photoluminescence upconversion is particularly well suited for studying band alignment at heterojunction interface. The value of band-offset has been determined with meV precision using magneto-photoluminescence. Using the fact that the pressure coefficient of electrons in GaAs is higher than those in GaInP{sub 2} they have been able to manipulate the band-offset at the GaInP/GaAs interface. By converting the band-offset from Type I to Type II they were able to demonstrate that the efficiency of the upconversion process is greatly enhanced by a Type II band-offset.

  2. Using satellite data to estimate partial pressure of CO2 in the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Parard, Gaëlle; Charantonis, Anastase Alexandre; Rutgersson, Anna

    2016-03-01

    In this study we focused on estimating the pressure partial of CO2 (pCO2) in the entire Baltic Sea which can be considered a coastal area in its entirety. We used the self-organizing multiple linear output (SOMLO) method to estimate the ocean surface pCO2 in the Baltic Sea from the remotely sensed sea surface temperature, chlorophyll a, colored dissolved organic matter, net primary production, and mixed-layer depth. Uncertainties in the estimates include sparsity of in situ data used to train the algorithms, in particular, for some sectors and seasons. For this application we divided the Baltic Sea in four basins. When comparing the results obtained with this division to those obtained in previous studies, we notice a decrease in the root-mean-square error (<40 μatm) between the reconstruction of the pCO2 and their corresponding in situ measurements, as well as an increase of the correlation coefficient (> 0.96) between them. The outputs of this research have a horizontal resolution of 4 km and cover the 1998-2011 period. For the first time, a climatological mean distribution of surface water pCO2 over the Baltic Sea was calculated based on the SOMLO method with a mean pCO2 of 368.3 ± 100 μatm, and a range of 234-514 μatm. The seasonal variability is similar throughout the Baltic Sea, being high in winter and low in summer.

  3. Non-site-specific allosteric effect of oxygen on human hemoglobin under high oxygen partial pressure

    PubMed Central

    Takayanagi, Masayoshi; Kurisaki, Ikuo; Nagaoka, Masataka

    2014-01-01

    Protein allostery is essential for vital activities. Allosteric regulation of human hemoglobin (HbA) with two quaternary states T and R has been a paradigm of allosteric structural regulation of proteins. It is widely accepted that oxygen molecules (O2) act as a “site-specific” homotropic effector, or the successive O2 binding to the heme brings about the quaternary regulation. However, here we show that the site-specific allosteric effect is not necessarily only a unique mechanism of O2 allostery. Our simulation results revealed that the solution environment of high O2 partial pressure enhances the quaternary change from T to R without binding to the heme, suggesting an additional “non-site-specific” allosteric effect of O2. The latter effect should play a complementary role in the quaternary change by affecting the intersubunit contacts. This analysis must become a milestone in comprehensive understanding of the allosteric regulation of HbA from the molecular point of view. PMID:24710521

  4. Fiber Optic Chemical Sensor For The Measurement Of Partial Pressure Of Oxygen

    NASA Astrophysics Data System (ADS)

    Goswami, Kisholoy; Klainer, Stanley M.; Tokar, John M.

    1989-01-01

    The estimation of partial pressure of oxygen in gaseous samples, aqueous samples and biological fluids has very important ramifications in environmental, medicinal and analytical chemistry. We have devised a fiber optic chemical sensor for the determination of oxygen concentration based on the dynamic luminescence quenching of a fluorophore bx oxygen. Ruthenium(II)tris(bipyridine), [Ru(bpy)3]4+, has been employed in our studies as the oxygen sensitive dye. The emission of Ru(bpy)32+ is centered at 610 nm and has a lifetime of 685 ns in argon purged aqueous solution. Our fiber optic chemical sensor consists of a custom built spectrometer containing argon ion laser light source, detector and associated electronics. A fiber optic cable is employed to guide light into and out of the spectrometer. A known amount of the sensing material in solution is used in a specially designed cell which has a gas permeable membrane at one end and the other end is coupled with the long cable to the spectrometer. Further research is being continued in improving the sensor chemistry and its dynamic detection range.

  5. Measurement of the oxygen partial pressure and thermodynamic modeling of the U-Nd-O system

    NASA Astrophysics Data System (ADS)

    Lee, Seung Min; Knight, Travis W.; McMurray, Jacob W.; Besmann, Theodore M.

    2016-05-01

    Fission products greatly impact the properties of fuel necessitating a thorough understanding of the thermochemical properties of oxide fuels with fission products. However, thermochemical data for the U-Nd-O system is insufficient even though neodymium is a major fission product. As neodymium will likely be present as a solute in UO2, this research focuses on the study of (U1-yNdy)O2±x. Experimental measurements and analyses of the oxygen partial pressure (pO2)-temperature-oxygen to metal ratio (O/M ratio) relationships were performed using a thermogravimetric analyzer (TGA) and an oxygen analyzer. Thermodynamic computational modeling was performed using the CALPHAD (CALculation of PHAse Diagrams) method with the FactSage software. The Gibbs energy of the (U1-yNdy)O2±x solid solution was described by the compound energy formalism (CEF), which is based on earlier thermodynamic modeling data of the binary U-O system from Guéneau et al.. The thermodynamic and phase diagram data of the U-Nd-O system produced in this work show good agreement with the experimental data.

  6. Influence of oxygen partial pressure and silver additions on microstructure and related properties of YBCO superconductors

    SciTech Connect

    Singh, J.P.; Joo, J.; Guttschow, R.; Poeppel, R.B.

    1992-02-01

    Microstructure has a great influence on the mechanical and superconducting properties of YBCO. Mechanical properties of YBCO can be improved by both modifying the monolithic microstructure and developing composites of YBCO with silver (Ag). When monolithic YBCO was sintered to high densities ({approx} 91%) at a relatively low temperature ({approx} 910{degrees}C) by controlling oxygen partial pressure during sintering, the result was a small-grain microstructure (average grain size {approx} 5 {mu}m) and hence a high strength of 191 {plus minus} 7 MPa. Addition of Ag as a second phase further improved the strength of YBCO. Composites of YBCO with 10 to 15 vol % Ag has a strength of 225 {plus minus} 6 MPa and a fracture toughness of 3.3 {plus minus} 0.2 MPa{radical}m. These improvements are believed to be due to compressive stresses in the YBCO matrix as a result of thermal mismatch between the YBCO and Ag phases. Furthermore, the Ag particles may provide increased resistance to crack propagation by pinning the crack. On the other hand, addition of Ag as a dopant to substitute for Cu sites in YBCO has a profound but nonmonotonic effect on grain microstructure and the resulting critical current density.

  7. Influence of oxygen partial pressure and silver additions on microstructure and related properties of YBCO superconductors

    SciTech Connect

    Singh, J.P.; Joo, J.; Guttschow, R.; Poeppel, R.B.

    1992-02-01

    Microstructure has a great influence on the mechanical and superconducting properties of YBCO. Mechanical properties of YBCO can be improved by both modifying the monolithic microstructure and developing composites of YBCO with silver (Ag). When monolithic YBCO was sintered to high densities ({approx} 91%) at a relatively low temperature ({approx} 910{degrees}C) by controlling oxygen partial pressure during sintering, the result was a small-grain microstructure (average grain size {approx} 5 {mu}m) and hence a high strength of 191 {plus_minus} 7 MPa. Addition of Ag as a second phase further improved the strength of YBCO. Composites of YBCO with 10 to 15 vol % Ag has a strength of 225 {plus_minus} 6 MPa and a fracture toughness of 3.3 {plus_minus} 0.2 MPa{radical}m. These improvements are believed to be due to compressive stresses in the YBCO matrix as a result of thermal mismatch between the YBCO and Ag phases. Furthermore, the Ag particles may provide increased resistance to crack propagation by pinning the crack. On the other hand, addition of Ag as a dopant to substitute for Cu sites in YBCO has a profound but nonmonotonic effect on grain microstructure and the resulting critical current density.

  8. Electronic properties and strain sensitivity of CVD-grown graphene with acetylene

    NASA Astrophysics Data System (ADS)

    Yang, Meng; Sasaki, Shinichirou; Ohnishi, Masato; Suzuki, Ken; Miura, Hideo

    2016-04-01

    Although many studies have shown that large-area monolayer graphene can be formed by chemical vapor deposition (CVD) using methane gas, the growth of monolayer graphene using highly reactive acetylene gas remains a big challenge. In this study, we synthesized a uniform monolayer graphene film by low-pressure CVD (LPCVD) with acetylene gas. On the base of Raman spectroscopy measurements, it was found that up to 95% of the as-grown graphene is monolayer. The electronic properties and strain sensitivity of the LPCVD-grown graphene with acetylene were also evaluated by testing the fabricated field-effect transistors (FETs) and strain sensors. The derived carrier mobility and gauge factor are 862-1150 cm2/(V·s) and 3.4, respectively, revealing the potential for high-speed FETs and strain sensor applications. We also investigated the relationship between the electronic properties and the graphene domain size.

  9. Oxygen partial pressure influenced structural and optical properties of DC magnetron sputtered ZrO{sub 2} films

    SciTech Connect

    Kondaiah, P.; Madhavi, V.; Uthanna, S.

    2013-02-05

    Thin films of zirconium oxide (ZrO{sub 2}) were deposited on (100) p-silicon and quartz substrates by sputtering of metallic zirconium target under different oxygen partial pressures in the range 8 Multiplication-Sign 10{sup -3}-6 Multiplication-Sign 10{sup -2}Pa. The effect of oxygen partial pressure on the structural and optical properties of the deposited films was systematically investigated. The deposition rate of the films decreased from 3.3 to 1.83 nm/min with the increase of oxygen partial pressure from 8 Multiplication-Sign 10{sup -3}-6 Multiplication-Sign 10{sup -2}Pa respectively. The X-ray diffraction profiles revealed that the films exhibit (111) refection of zirconium oxide in monoclinic phase. The optical band gap of the films increased from 5.62 to 5.80 eV and refractive index increased from 2.01 to 2.08 with the increase of oxygen partial pressure from 8 Multiplication-Sign 10{sup -3}-6 Multiplication-Sign 10{sup -2}Pa respectively.

  10. Influence of oxygen partial pressure on the microstructural and magnetic properties of Er-doped ZnO thin films

    NASA Astrophysics Data System (ADS)

    Chen, Wei-Bin; Liu, Xue-Chao; Li, Fei; Chen, Hong-Ming; Zhou, Ren-Wei; Shi, Er-Wei

    2015-06-01

    Er-doped ZnO thin films have been prepared by using inductively coupled plasma enhanced physical vapor deposition at different O2:Ar gas flow ratio (R = 0:30, 1:30, 1:15, 1:10 and 1:6). The influence of oxygen partial pressure on the structural, optical and magnetic properties was studied. It is found that an appropriate oxygen partial pressure (R=1:10) can produce the best crystalline quality with a maximum grain size. The internal strain, estimated by fitting the X-ray diffraction peaks, varied with oxygen partial pressure during growth. PL measurements show that plenty of defects, especially zinc vacancy, exist in Er-doped ZnO films. All the samples show room-temperature ferromagnetism. Importantly, the saturation magnetization exhibits similar dependency on oxygen partial pressure with the internal strain, which indicates that internal strain has an important effect on the magnetic properties of Er-doped ZnO thin films.

  11. Oxygen partial pressure influenced structural and optical properties of DC magnetron sputtered ZrO2 films

    NASA Astrophysics Data System (ADS)

    Kondaiah, P.; Madhavi, V.; Uthanna, S.

    2013-02-01

    Thin films of zirconium oxide (ZrO2) were deposited on (100) p-silicon and quartz substrates by sputtering of metallic zirconium target under different oxygen partial pressures in the range 8×10-3-6×10-2Pa. The effect of oxygen partial pressure on the structural and optical properties of the deposited films was systematically investigated. The deposition rate of the films decreased from 3.3 to 1.83 nm/min with the increase of oxygen partial pressure from 8×10-3-6×10-2Pa respectively. The X-ray diffraction profiles revealed that the films exhibit (111) refection of zirconium oxide in monoclinic phase. The optical band gap of the films increased from 5.62 to 5.80 eV and refractive index increased from 2.01 to 2.08 with the increase of oxygen partial pressure from 8×10-3-6×10-2Pa respectively.

  12. Effect of oxygen partial pressure on microstructural and optical properties of titanium oxide thin films prepared by pulsed laser deposition

    SciTech Connect

    Balakrishnan, G.; Bandi, Vengala Rao; Rajeswari, S.M.; Balamurugan, N.; Babu, R. Venkatesh; Song, J.I.

    2013-11-15

    Graphical abstract: - Highlights: • Microstructural and optical properties are studied systematically. • The optical properties are studied by UV–visible and photoluminescence. • The PL spectra shows two peaks correspond to bandgap of anatase and rutile. • The maximum refractive index of 2.73 is obtained for rutile phase of titania. - Abstract: Nanocrystalline titanium oxide (TiO{sub 2}) thin films were deposited on silicon (1 0 0) and quartz substrates at various oxygen partial pressures (1 × 10{sup −5} to 3.5 × 10{sup −1} mbar) with a substrate temperature of 973 K by pulsed laser deposition. The microstructural and optical properties were characterized using Grazing incidence X-ray diffraction, atomic force microscopy, UV–visible spectroscopy and photoluminescence. The X-ray diffraction studies indicated the formation of mixed phases (anatase and rutile) at higher oxygen partial pressures (3.5 × 10{sup −2} to 3.5 × 10{sup −1} mbar) and strong rutile phase at lower oxygen partial pressures (1 × 10{sup −5} to 3.5 × 10{sup −3} mbar). The atomic force microscopy studies showed the dense and uniform distribution of nanocrystallites. The root mean square surface roughness of the films increased with increasing oxygen partial pressures. The UV–visible studies showed that the bandgap of the films increased from 3.20 eV to 3.60 eV with the increase of oxygen partial pressures. The refractive index was found to decrease from 2.73 to 2.06 (at 550 nm) as the oxygen partial pressure increased from 1.5 × 10{sup −4} mbar to 3.5 × 10{sup −1} mbar. The photoluminescence peaks were fitted to Gaussian function and the bandgap was found to be in the range ∼3.28–3.40 eV for anatase and 2.98–3.13 eV for rutile phases with increasing oxygen partial pressure from 1 × 10{sup −5} to 3.5 × 10{sup −1} mbar.

  13. Pressures of Partial Crystallization along the East Pacific Rise: Preliminary Results and Evidence for Deep Crustal Chambers?

    NASA Astrophysics Data System (ADS)

    Zerda, C.; Scott, J. L.; Barton, M.

    2013-12-01

    The fast spreading East Pacific Rise (EPR) between 8°N and 14°N is characterized by ~20 ridge axis discontinuities. Previous work has suggested that magmas erupted at some of these discontinuities, specifically at transform faults, partially crystallize at higher pressures than magmas erupted along 'normal' ridge segments. In order to evaluate the factors that control the plumbing systems of MORB, we have determined the pressures (P) of partial crystallization of magmas beneath the EPR from 8°N to 14°N using 2,837 published chemical analyses of basalt glasses. Pressures were calculated using the two different methods described by Herzberg, 2004 (H) and Kelley and Barton, 2008 (KB). These two methods are expected to yield minimum and maximum values for calculated pressures. However, for the samples used in this work both methods yield virtually identical pressures for the entire data set (average pressures: H=182.3×143.6 MPa and KB=200.9×153.3 MPa) and we elected to use results obtained with the KB method for detailed analysis of the results. Based on sample frequency, the EPR was divided into 10 sections that include 'normal' segments lacking axial discontinuities and segments that include discontinuities such as a transform fault, an overlapping spreading center (OSC), or a deviation from axial linearity, or one or more of these features. The average pressure of partial crystallization for 'normal' segments is 145.6×59.9 MPa, and is essentially constant along the whole length of the ridge studied. These results are consistent with crystallization at depths of ~ 5km near the base of the crust and, as with results obtained for the Juan da Fuca and Reykjanes ridge, provide no evidence for crystallization in the upper mantle along 'normal' ridge segments. The pressures of partial crystallization of magmas at or near axial discontinuities show a wider range than those for magmas erupted along normal ridge segments. The maximum pressures for samples from the

  14. Microvascular oxygen partial pressure during hyperbaric oxygen in diabetic rat skeletal muscle.

    PubMed

    Yamakoshi, Kohei; Yagishita, Kazuyoshi; Tsuchimochi, Hirotsugu; Inagaki, Tadakatsu; Shirai, Mikiyasu; Poole, David C; Kano, Yutaka

    2015-12-15

    Hyperbaric oxygen (HBO) is a major therapeutic treatment for ischemic ulcerations that perforate skin and underlying muscle in diabetic patients. These lesions do not heal effectively, in part, because of the hypoxic microvascular O2 partial pressures (PmvO2 ) resulting from diabetes-induced cardiovascular dysfunction, which alters the dynamic balance between O2 delivery (Q̇o2) and utilization (V̇o2) rates. We tested the hypothesis that HBO in diabetic muscle would exacerbate the hyperoxic PmvO2 dynamics due, in part, to a reduction or slowing of the cardiovascular, sympathetic nervous, and respiratory system responses to acute HBO exposure. Adult male Wistar rats were divided randomly into diabetic (DIA: streptozotocin ip) and healthy (control) groups. A small animal hyperbaric chamber was pressurized with oxygen (100% O2) to 3.0 atmospheres absolute (ATA) at 0.2 ATA/min. Phosphorescence quenching techniques were used to measure PmvO2 in tibialis anterior muscle of anesthetized rats during HBO. Lumbar sympathetic nerve activity (LSNA), heart rate (HR), and respiratory rate (RR) were measured electrophysiologically. During the normobaric hyperoxia and HBO, DIA tibialis anterior PmvO2 increased faster (mean response time, CONT 78 ± 8, DIA 55 ± 8 s, P < 0.05) than CONT. Subsequently, PmvO2 remained elevated at similar levels in CONT and DIA muscles until normobaric normoxic recovery where the DIA PmvO2 retained its hyperoxic level longer than CONT. Sympathetic nervous system and cardiac and respiratory responses to HBO were slower in DIA vs. CONT. Specifically the mean response times for RR (CONT: 6 ± 1 s, DIA: 29 ± 4 s, P < 0.05), HR (CONT: 16 ± 1 s, DIA: 45 ± 5 s, P < 0.05), and LSNA (CONT: 140 ± 16 s, DIA: 247 ± 34 s, P < 0.05) were greater following HBO onset in DIA than CONT. HBO treatment increases tibialis anterior muscle PmvO2 more rapidly and for a longer duration in DIA than CONT, but not to a greater level. Whereas respiratory, cardiovascular

  15. Global autocorrelation scales of the partial pressure of oceanic CO2

    NASA Astrophysics Data System (ADS)

    Li, Zhen; Adamec, David; Takahashi, Taro; Sutherland, Stewart C.

    2005-08-01

    A global database of approximately 1.7 million observations of the partial pressure of carbon dioxide in surface ocean waters (pCO2) collected between 1970 and 2003 is used to estimate its spatial autocorrelation structure. The patterns of the lag distance where the autocorrelation exceeds 0.8 is similar to patterns in the spatial distribution of the first baroclinic Rossby radius of deformation indicating that ocean circulation processes play a significant role in determining the spatial variability of pCO2. Separate calculations for times when the Sun is north and south of the equator revealed no obvious seasonal dependence of the spatial autocorrelation scales. The pCO2 measurements at Ocean Weather Station (OWS) "P" in the eastern subarctic Pacific (50°N, 145°W) is the only fixed location where an uninterrupted time series of sufficient length exists to calculate a meaningful temporal autocorrelation function for lags greater than a few days. The estimated temporal autocorrelation function at OWS "P" is highly variable. A spectral analysis of the longest four pCO2 time series indicates a high level of variability occurring over periods from the atmospheric synoptic to the maximum length of the time series, in this case 42 days. It is likely that a relative peak in variability with a period of 3-6 days is related to atmospheric synoptic period variability and ocean mixing events due to wind stirring. However, the short length of available time series makes identifying temporal relationships between pCO2 and atmospheric or ocean processes problematic.

  16. Global Autocorrelation Scales of the Partial Pressure of Oceanic CO2

    NASA Technical Reports Server (NTRS)

    Li, Zhen; Adamec, David; Takahashi, Taro; Sutherland, Stewart C.

    2004-01-01

    A global database of approximately 1.7 million observations of the partial pressure of carbon dioxide in surface ocean waters (pCO2) collected between 1970 and 2003 is used to estimate its spatial autocorrelation structure. The patterns of the lag distance where the autocorrelation exceeds 0.8 is similar to patterns in the spatial distribution of the first baroclinic Rossby radius of deformation indicating that ocean circulation processes play a significant role in determining the spatial variability of pCO2. For example, the global maximum of the distance at which autocorrelations exceed 0.8 averages about 140 km in the equatorial Pacific. Also, the lag distance at which the autocorrelation exceed 0.8 is greater in the vicinity of the Gulf Stream than it is near the Kuroshio, approximately 50 km near the Gulf Stream as opposed to 20 km near the Kuroshio. Separate calculations for times when the sun is north and south of the equator revealed no obvious seasonal dependence of the spatial autocorrelation scales. The pCO2 measurements at Ocean Weather Station (OWS) 'P', in the eastern subarctic Pacific (50 N, 145 W) is the only fixed location where an uninterrupted time series of sufficient length exists to calculate a meaningful temporal autocorrelation function for lags greater than a few days. The estimated temporal autocorrelation function at OWS 'P', is highly variable. A spectral analysis of the longest four pCO2 time series indicates a high level of variability occurring over periods from the atmospheric synoptic to the maximum length of the time series, in this case 42 days. It is likely that a relative peak in variability with a period of 3-6 days is related to atmospheric synoptic period variability and ocean mixing events due to wind stirring. However, the short length of available time series makes identifying temporal relationships between pCO2 and atmospheric or ocean processes problematic.

  17. Why is the partial oxygen pressure of human tissues a crucial parameter? Small molecules and hypoxia

    PubMed Central

    Carreau, Aude; Hafny-Rahbi, Bouchra El; Matejuk, Agata; Grillon, Catherine; Kieda, Claudine

    2011-01-01

    Abstract Oxygen supply and diffusion into tissues are necessary for survival. The oxygen partial pressure (pO2), which is a key component of the physiological state of an organ, results from the balance between oxygen delivery and its consumption. In mammals, oxygen is transported by red blood cells circulating in a well-organized vasculature. Oxygen delivery is dependent on the metabolic requirements and functional status of each organ. Consequently, in a physiological condition, organ and tissue are characterized by their own unique ‘tissue normoxia’ or ‘physioxia’ status. Tissue oxygenation is severely disturbed during pathological conditions such as cancer, diabetes, coronary heart disease, stroke, etc., which are associated with decrease in pO2, i.e. ‘hypoxia’. In this review, we present an array of methods currently used for assessing tissue oxygenation. We show that hypoxia is marked during tumour development and has strong consequences for oxygenation and its influence upon chemotherapy efficiency. Then we compare this to physiological pO2 values of human organs. Finally we evaluate consequences of physioxia on cell activity and its molecular modulations. More importantly we emphasize the discrepancy between in vivo and in vitro tissue and cells oxygen status which can have detrimental effects on experimental outcome. It appears that the values corresponding to the physioxia are ranging between 11% and 1% O2 whereas current in vitro experimentations are usually performed in 19.95% O2, an artificial context as far as oxygen balance is concerned. It is important to realize that most of the experiments performed in so-called normoxia might be dangerously misleading. PMID:21251211

  18. Microenvironmental oxygen partial pressure in acute myeloid leukemia: Is there really a role for hypoxia?

    PubMed

    Rieger, Christina T; Fiegl, Michael

    2016-07-01

    Reduced oxygen partial pressure (pO2) has been recognized as being relevant in hematopoiesis and the pathophysiology of malignant diseases. Although hypoxic (meaning insufficient supply of oxygen) and anoxic areas are present and of pathophysiologic importance (by hypoxia-induced pathways such as HiF1α) in solid tumors, this may not be true for (malignant) hematologic cells. Hematopoiesis occurs in the stem cell niche, which is characterized, among other things, by extremely low pO2. However, in contrast to solid tumors, in this context, the low pO2 is physiological and this feature, among others, is shared by the malignant stem cell niche harboring leukemia-initiating cells. Upon differentiation, hematopoietic cells are constantly exposed to changes in pO2 as they travel throughout the human body and encounter arterial and venous blood and migrate into oxygen-carrier-free tissue with low pO2. Hematologic malignancies such as acute myeloid leukemia (AML) make little difference in this respect and, whereas low oxygen is the usual environment of AML cells, recent evidence suggests no role for real hypoxia. Although there is no evidence that AML pathophysiology is related to hypoxia, leukemic blasts still show several distinct biological features when exposed to reduced pO2: they down- or upregulate membrane receptors such as CXCR4 or FLT3, activate or inhibit intracellular signaling pathways such as PI3K, and specifically secrete cytokines (IL-8). In summary, reduced pO2 should not be mistaken for hypoxia (nor should it be so called), and it does not automatically induce hypoxia-response mechanisms; therefore, a strict distinction should be made between physiologically low pO2 (physoxia) and hypoxia. PMID:27118044

  19. Partial pharmacologic blockade shows sympathetic connection between blood pressure and cerebral blood flow velocity fluctuations.

    PubMed

    Hilz, Max J; Wang, Ruihao; Marthol, Harald; Liu, Mao; Tillmann, Alexandra; Riss, Stephan; Hauck, Paulina; Hösl, Katharina M; Wasmeier, Gerald; Stemper, Brigitte; Köhrmann, Martin

    2016-06-15

    Cerebral autoregulation (CA) dampens transfer of blood pressure (BP)-fluctuations onto cerebral blood flow velocity (CBFV). Thus, CBFV-oscillations precede BP-oscillations. The phase angle (PA) between sympathetically mediated low-frequency (LF: 0.03-0.15Hz) BP- and CBFV-oscillations is a measure of CA quality. To evaluate whether PA depends on sympathetic modulation, we assessed PA-changes upon sympathetic stimulation with and without pharmacologic sympathetic blockade. In 10 healthy, young men, we monitored mean BP and CBFV before and during 120-second cold pressor stimulation (CPS) of one foot (0°C ice-water). We calculated mean values, standard deviations and sympathetic LF-powers of all signals, and PAs between LF-BP- and LF-CBFV-oscillations. We repeated measurements after ingestion of the adrenoceptor-blocker carvedilol (25mg). We compared parameters before and during CPS, without and after carvedilol (analysis of variance, post-hoc t-tests, significance: p<0.05). Without carvedilol, CPS increased BP, CBFV, BP-LF- and CBFV-LF-powers, and shortened PA. Carvedilol decreased resting BP, CBFV, BP-LF- and CBFV-LF-powers, while PAs remained unchanged. During CPS, BPs, CBFVs, BP-LF- and CBFV-LF-powers were lower, while PAs were longer with than without carvedilol. With carvedilol, CPS no longer shortened resting PA. Sympathetic activation shortens PA. Partial adrenoceptor blockade abolishes this PA-shortening. Thus, PA-measurements provide a subtle marker of sympathetic influences on CA and might refine CA evaluation. PMID:27206903

  20. Alveolar partial pressures of carbon dioxide and oxygen measured by a helium washout technique.

    PubMed Central

    Jordanoglou, J; Tatsis, G; Danos, J; Gougoulakis, S; Orfanidou, D; Gaga, M

    1990-01-01

    A non-invasive technique was developed for measuring alveolar carbon dioxide and oxygen tension during tidal breathing. This was achieved by solving the Bohr equations for mean alveolar carbon dioxide and oxygen tensions (PACO2, PAO2) from known values of the dead-space:tidal volume ratio measured by helium washout, and from the mixed expired partial pressure of carbon dioxide and oxygen. The derived values of wPACO2 and wPAO2 were compared with PaCO2 obtained from arterial gas analysis and PAO2 calculated from the ideal air equation. Four normal subjects and 58 patients were studied. Calculated and measured PCO2 values agreed closely with a difference in mean values (wPACO2 - PaCO2) of 0.01 kPa; the SD of the differences was 0.7 kPa. The difference in mean values between wPAO2 and PAO2 was 0.02 kPa; the SD of the differences was 0.93 kPa. The method is simple and not time consuming, and requires no special cooperation from the patients. It can be applied in the laboratory or at the bedside to any subject breathing tidally. Physiological deadspace:tidal volume ratio, PAO2 and PACO2, static lung volumes, respiratory exchange ratio, carbon dioxide production, oxygen uptake, tidal volume, and total ventilation can be measured with acceptable accuracy and reproducibility in one test. An arterial blood sample is needed initially to provide an independent measure of PaCO2 and for measurement of the alveolar-arterial PO2 difference. Subsequently, PaCO2 can be estimated from wPACO2 sufficiently well for clinical purposes and PaO2 or SaO2 can be monitored by non-invasive methods. Images PMID:2118690

  1. The effects of total gas pressure and Xe partial pressure on the properties of plasma display panels with two-opposite-electrode cells

    NASA Astrophysics Data System (ADS)

    Ok, Jung-Woo; Lee, Byoung-Seob; Choi, Seyong; Won, Mi-Sook; Kim, Dong-Hyun; Lee, Hae June; Lee, Ho-Jun

    2014-04-01

    The effects of total pressure and Xe partial pressure on the characteristics of an alternating-current plasma display panel with a two-opposite-electrode discharge cell configuration and a three-electrode surface-discharge cell configuration were investigated in terms of the following electro-optical properties: breakdown voltage, sustain voltage, wall charge transfer curve, infrared emission characteristics, luminance and luminous efficacy. Despite the longer discharge gap length, the results of the experiment and three-dimensional plasma simulation indicated that the opposite-discharge configuration has a significantly lower breakdown voltage than the surface-discharge configuration. Furthermore, the ratio of the increase in the breakdown voltage for the opposite-discharge configuration to the incremental Xe partial pressure was found to be smaller than that of the surface-discharge configuration. Because of its low driving voltage and possible use of high-Xe partial pressure, the opposite-discharge mode exhibited a higher luminous efficacy compared with the surface-discharge mode. These results indicated that the two-opposite-electrode discharge cell configuration has a cost reduction potential in electronics as well as high efficacy for plasma displays.

  2. Influence of oxygen partial pressure on the structural, optical and electrical properties of Cu-doped NiO thin films

    NASA Astrophysics Data System (ADS)

    Reddy, Y. Ashok Kumar; Sivasankar Reddy, A.; Sreedhara Reddy, P.

    2013-01-01

    The NiO-Cu composite thin films were successfully deposited on Corning 7059 glass substrates at different oxygen partial pressures in the range of 9 × 10-5-6 × 10-4 mbar using the dc reactive magnetron sputtering technique. All the deposited films were of polycrystalline nature and exhibited cubic structure with preferential growth. The optical transmittance and band gap of the films increased with increasing the oxygen partial pressure up to 2 × 10-4 mbar and decreased on further increasing the oxygen partial pressure. From the surface morphological studies, fine and uniform grains were observed at an oxygen partial pressure of 2 × 10-4 mbar. Compositional analysis indicated that Ni content increased and Cu content decreased with increasing the oxygen partial pressure. The resistivity values decreased gradually from 64 to 10 Ω cm with increasing the oxygen pressure to 6 × 10-4 mbar.

  3. Effect of Acetylene on Root Respiration and Acetylene Reducing Activity in Nodulated Soya Bean

    PubMed Central

    Gerbaud, Alain

    1990-01-01

    Acetylene decreased root and nodule respiration, as measured by CO2 evolution of nodulated or non-nodulated Glycine max. An inhibition of 25 to 35% in 15 to 30 minutes occurred when 13% C2H2 was introduced in the gas flux which aerated the root nutrient solution. When the light intensity was doubled to 800 microeinsteins per square meter per second, the inhibition increased to 50% and nodule acetylene reduction activity was inhibited 50%. Images Figure 1 PMID:16667582

  4. Hydration of Acetylene: A 125th Anniversary

    ERIC Educational Resources Information Center

    Ponomarev, Dmitry A.; Shevchenko, Sergey M.

    2007-01-01

    The year 2006 is the 125th anniversary of a chemical reaction, the discovery of which by Mikhail Kucherov had a profound effect on the development of industrial chemistry in the 19-20th centuries. This was the hydration of alkynes catalyzed by mercury ions that made possible industrial production of acetaldehyde from acetylene. Historical…

  5. Living on acetylene. A primordial energy source.

    PubMed

    Ten Brink, Felix

    2014-01-01

    The tungsten iron-sulfur enzyme acetylene hydratase catalyzes the conversion of acetylene to acetaldehyde by addition of one water molecule to the C-C triple bond. For a member of the dimethylsulfoxide (DMSO) reductase family this is a rather unique reaction, since it does not involve a net electron transfer. The acetylene hydratase from the strictly anaerobic bacterium Pelobacter acetylenicus is so far the only known and characterized acetylene hydratase. With a crystal structure solved at 1.26 Å resolution and several amino acids around the active site exchanged by site-directed mutagenesis, many key features have been explored to understand the function of this novel tungsten enzyme. However, the exact reaction mechanism remains unsolved. Trapped in the reduced W(IV) state, the active site consists of an octahedrally coordinated tungsten ion with a tightly bound water molecule. An aspartate residue in close proximity, forming a short hydrogen bond to the water molecule, was shown to be essential for enzyme activity. The arrangement is completed by a small hydrophobic pocket at the end of an access funnel that is distinct from all other enzymes of the DMSO reductase family. PMID:25416389

  6. Oxygen partial pressure influence on the character of InGaZnO thin films grown by PLD

    NASA Astrophysics Data System (ADS)

    Lu, Yi; Wang, Li

    2012-11-01

    The amorphous oxide semiconductors (AOSs) are promising for emerging large-area optoelectronic applications because of capability of large-area, uniform deposition at low temperatures such as room temperature (RT). Indium-gallium-zinc oxide (InGaZnO) thin film is a promising amorphous semiconductors material in thin film transistors (TFT) for its excellent electrical properties. In our work, the InGaZnO thin films are fabricated on the SiO2 glass using pulsed laser deposition (PLD) in the oxygen partial pressure altered from 1 to 10 Pa at RT. The targets were prepared by mixing Ga2O3, In2O3, and ZnO powder at a mol ratio of 1: 7: 2 before the solid-state reactions in a tube furnace at the atmospheric pressure. The targets were irradiated by an Nd:YAG laser(355nm). Finally, we have three films of 270nm, 230nm, 190nm thick for 1Pa, 5Pa, 10Pa oxygen partial pressure. The product thin films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), Hall-effect investigation. The comparative study demonstrated the character changes of the structure and electronic transport properties, which is probably occurred as a fact of the different oxygen partial pressure used in the PLD.

  7. Impact of Xe partial pressure on the production of excimer vacuum ultraviolet emission for plasma display panels

    SciTech Connect

    Zhu Di; Zhang Xiong; Kajiyama, Hiroshi

    2012-08-01

    In this work, the effect of the Xe partial pressure on the excimer vacuum ultraviolet (VUV) emission intensity of the plasma display panels is investigated, both by measuring the spectral emission directly and by two-dimensional simulations. Experimentally, we find that at the high Xe partial pressure levels, there is an supra-linear increase of excimer VUV radiation and that determines the strong increase of luminance at the high pressures and high voltage. Due to the increase of the luminance and the almost unchanged discharge current, the luminous efficacy strongly increases with the Xe partial pressure. In addition, we also investigated the dynamics of the VUV generation, by measuring the decay time of the excimer VUV light as a function of the gas pressure. It is found that the decay time decreases with the increase of gas pressure. The spatial characteristics of the excimer VUV emission are also discussed. Different from the Ne and near-infrared emission, the excimer VUV emission is generated near the surface of the electrodes and increases uniformly on both sides of the anode and cathode (i.e., the bulk plasma region). Most importantly, it is found that the VUV production occurs during the afterglow period, while it is almost zero at the moment of the discharge itself. From the simulations, it can be seen that the Xe{sub 2}*({sup 3}{Sigma}{sub u}{sup +}) excimer species, which are generated from Xe*(1s{sub 5}), play a dominant role in the excimer VUV emission output at the high Xe partial pressure. The two-dimensional simulations also show that the strong increase of Xe excimer excitation states in the case of high pressure is mainly the result of the high conversion efficiency of the Xe excimer states, especially in the afterglow period. Due to the high conversion efficiency of Xe excitation species to Xe excimer species by the high collision rate in the case of high pressure, there is a strong increase of excimer VUV production, especially from the cathode.

  8. Acetylene measurement in flames by chirp-based quantum cascade laser spectrometry.

    PubMed

    Quine, Zachary R; McNesby, Kevin L

    2009-06-01

    We have designed and characterized a mid-IR spectrometer built around a pulsed distributed-feedback quantum cascade laser using the characteristic frequency down-chirp to scan through the spectral region 6.5 cm(-1) spectral region. The behavior of this chirp is extensively measured. The accuracy and detection limits of the system as an absorption spectrometer are demonstrated first by measuring spectra of acetylene through a single pass 16 cm absorption cell in real time at low concentrations and atmospheric pressure. The smallest detectable peak is measured to be approximately 1.5 x 10(-4) absorbance units, yielding a minimum detectable concentration length product of 2.4 parts per million meter at standard temperature and pressure. This system is then used to detect acetylene within an ethylene-air opposed flow flame. Measurements of acetylene content as a function of height above the fuel source are presented, as well as measurements of acetylene produced in fuel breakdown as a function of preinjection fuel temperature. PMID:19488121

  9. Carbon dioxide partial pressure and carbon fluxes of air-water interface in Taihu Lake, China

    NASA Astrophysics Data System (ADS)

    Fan, Chengxin; Hu, Weiping; Ford, Phillip W.; Chen, Yuwei; Qu, Wenchuan; Zhang, Lu

    2005-03-01

    To obtain carbon dioxide (CO2) flux between water-air interface of Taihu lake, monthly water samplers at 14 sites and the local meteorological data of the lake were collected and analyzed in 1998. Carbon dioxide partial pressures (pCO2) at air-water interface in the lake were calculated using alkalinity, pH, ionic strength, active coefficient, and water temperature. The carbon fluxes at different sublakes and areas were estimated by concentration gradient between water and air in consideration of Schmidt numbers of 600 and daily mean windspeed at 10 m above water surface. The results indicated that the mean values of pCO2 in Wuli Lake, Meiliang Bay, hydrophyte area, west littoral zone, riverine mouths, and the open lake areas were 1 807.8±1 071.4 (mean±standard deviation) μatm (1atm=1.013 25×105Pa), 416.3±217.0 μatm, 576.5±758.8 μatm, 304.2±243.5 μatm, 1 933.6±1 144.7 μatm, and 448.5±202.6 μatm, respectively. Maximum and minimum pCO2 values were found in the hypertrophic (4 053.7 μatm) and the eutrophic (3.2 μatm) areas. The riverine mouth areas have the maximum fluxes (82.0±62.8 mmol/m2a). But there was no significant difference between eutrophic and mesotrophic areas in pCO2 and the flux of CO2. The hydrophyte area, however, has the minimum (-0.58±12.9 mmol/m2a). In respect to CO2 equilibrium, input of the rivers will obviously influence inorganic carbon distribution in the riverine estuary. For example, the annual mean CO2 flux in Zhihugang River estuary was 19 times of that in Meiliang Bay, although the former is only a part of the latter. The sites in the body of the lake show a clear seasonal cycle with pCO2 higher than atmospheric equilibrium in winter, and much lower than atmospheric in summer due to CO2 consumption by photosynthesis. The CO2 amount of the net annual evasion that enters the atmosphere is 28.42×104 t/a, of which those from the west littoral zone and the open lake account for 53.8% and 36.7%, respectively.

  10. Measurements of Pressure Distributions and Force Coefficients in a Squeeze Film Damper. Part 2: Partially Sealed Configuration

    NASA Technical Reports Server (NTRS)

    Jung, S. Y.; Sanandres, Luis A.; Vance, J. M.

    1991-01-01

    Experimental results from a partially sealed squeeze film damper (SFD) test rig, executing a circular centered orbit are presented and discussed. A serrated piston ring is installed at the damper exit. This device involves a new sealing concept which produces high damping values while allowing for oil flow to cool the damper. In the partially sealed damper, large cavitation regions are observed in the pressure fields at orbit radii epsilon equals 0.5 and epsilon equals 0.8. The cavitated pressure distributions and the corresponding force coefficients are compared with a cavitated bearing solution. The experimental results show the significance of fluid inertia and vapor cavitation in the operation of squeeze film dampers. Squeeze film Reynolds numbers tested reach up to Re equals 50, spanning the range of contemporary applications.

  11. A comparative study of the centrifugal and vacuum-pressure techniques of casting removable partial denture frameworks.

    PubMed

    Shanley, J J; Ancowitz, S J; Fenster, R K; Pelleu, G B

    1981-01-01

    A study was undertaken to evaluate two techniques for casting accuracy on removable partial denture frameworks: centrifugal casting and vacuum-pressure casting. A standard metal die with predetermined reference points in a horizontal plane was duplicated in refractory investment. The casts were waxed, and castings of nickel-chrome alloy were fabricated by the two techniques. Both the casts and the castings were measured between the reference points with a measuring microscope. With both casting methods, the differences between the casts and the castings were significant, but no significant differences were found between castings produced by the two techniques. Vertical measurements at three designated points also showed no significant differences between the castings. Our findings indicate that dental laboratories should be able to use the vacuum-pressure method of casting removable partial denture frameworks and achieve accuracy similar to that obtained by the centrifugal method of casting. PMID:7007622

  12. Effect of oxygen partial pressure and anneal temperature on BaTiO3 thin film crystal structure

    NASA Astrophysics Data System (ADS)

    Zhang, Jing; Sun, De-gui; Fu, Xiuhua; Liu, Dong-mei; Pan, Yong-gang; Yang, Fei

    2015-08-01

    BaTiO3 film is deposited on single crystal MgO substrate with pulsed laser deposition, and its crystal structure and surface roughness are characterized by X-ray diffraction instrument and atomic force microscope. BaTiO3 film crystal quality is analyzed under three different oxygen partial pressure and three different annealing temperatures. The result shows that when the oxygen partial pressure is 15Pa, crystal surface (001) and (002) diffraction peak of BaTiO3 thin films have higher intensity. It indicated that the film has a good c-axis orientation. When the annealing temperature is 800°C, the intensity of diffraction peak is the maximum, and peak shape is sharper. BaTiO3 crystal film is obtained with highly preferred orientation, and film density is improved. Thus the film has less surface roughness and good crystalline state.

  13. Measurement of Local Partial Pressure of Oxygen in the Brain Tissue under Normoxia and Epilepsy with Phosphorescence Lifetime Microscopy

    PubMed Central

    Zhang, Cong; Bélanger, Samuel; Pouliot, Philippe; Lesage, Frédéric

    2015-01-01

    In this work a method for measuring brain oxygen partial pressure with confocal phosphorescence lifetime microscopy system is reported. When used in conjunction with a dendritic phosphorescent probe, Oxyphor G4, this system enabled minimally invasive measurements of oxygen partial pressure (pO2) in cerebral tissue with high spatial and temporal resolution during 4-AP induced epileptic seizures. Investigating epileptic events, we characterized the spatio-temporal distribution of the "initial dip" in pO2 near the probe injection site and along nearby arterioles. Our results reveal a correlation between the percent change in the pO2 signal during the "initial dip" and the duration of seizure-like activity, which can help localize the epileptic focus and predict the length of seizure. PMID:26305777

  14. Two Phase Flow Modeling: Summary of Flow Regimes and Pressure Drop Correlations in Reduced and Partial Gravity

    NASA Technical Reports Server (NTRS)

    Balasubramaniam, R.; Rame, E.; Kizito, J.; Kassemi, M.

    2006-01-01

    The purpose of this report is to provide a summary of state-of-the-art predictions for two-phase flows relevant to Advanced Life Support. We strive to pick out the most used and accepted models for pressure drop and flow regime predictions. The main focus is to identify gaps in predictive capabilities in partial gravity for Lunar and Martian applications. Following a summary of flow regimes and pressure drop correlations for terrestrial and zero gravity, we analyze the fully developed annular gas-liquid flow in a straight cylindrical tube. This flow is amenable to analytical closed form solutions for the flow field and heat transfer. These solutions, valid for partial gravity as well, may be used as baselines and guides to compare experimental measurements. The flow regimes likely to be encountered in the water recovery equipment currently under consideration for space applications are provided in an appendix.

  15. [Bloodless determination of the partial pressure of oxygen in the gingiva as a longitudinal study conducted in the case of administration of hormonal contraceptives (author's transl)].

    PubMed

    Arnold, M

    1981-01-01

    22 women were included in a program to determine the partial pressure of oxygen on 3 papillae and on the alveolar gingiva before and after oxygen insufflation. Determination of the partial pressure of oxygen was by an indirect method and was made before as well as after 2, 4, and 6 months of administration of hormonal contraceptives. Statistical testing was by the Newman-Keuls test. The supply of oxygen may be readily detected using an indirect method. The partial pressure of oxygen was observed to decrease, at all points of measurement, up through the 4th month of administration of oral contraceptives (OCs), after which it was seen to again increase. There were similar though insignificant differences noted between the values recorded prior and subsequent to oxygen insufflation. It is possible to delimit general variations in partial pressure of oxygen under OCs from shifts in the partial pressure of oxygen due to inflammatory processes. (author's) PMID:6168138

  16. Method for sensing and measuring a concentration or partial pressure of a reactant used in a redox reaction

    DOEpatents

    Findl, E.

    1984-12-21

    A method for sensing or measuring the partial pressure or concentration of an electroactive species used in conjunction with an electrolyte, the method being characterized by providing a constant current between an anode and a cathode of an electrolyte-containing cell, while measuring changes in voltage that occur between either the anode and cathode or between a reference electrode and one of the main electrodes of the cell, thereby to determine the concentration or partial pressure of the electro-active species as a function of said measured voltage changes. The method of the invention can be practiced using either a cell having only an anode and a cathode, or using a cell having an anode and a cathode in combination with a reference electrode. Accurate measurements of small concentrations or partial pressures of electro-active species are obtainable with the method of the invention, by using constant currents of only a few microamperes between the anode and cathode of the cell, while the concentration-determining voltage is measured.

  17. Development of a silicone membrane tube equilibrator for measuring partial pressures of volatile organic compounds in natural water.

    PubMed

    Ooki, Atsushi; Yokouchi, Yoko

    2008-08-01

    Methods for determining volatile organic compounds (VOCs) in water and air are required so that the VOCs' fluxes in water environments can be estimated. We developed a silicone membrane tube equilibrator for collecting gas-phase samples containing VOCs at equilibrium with natural water. The equilibrator consists of six silicone tubes housed in a polyvinyl chloride pipe. Equilibrated air samples collected from the equilibrator were analyzed with an automated preconcentration gas chromatography-mass spectrometry system for hourly measurements of VOC partial pressures. The partial pressures of all the target VOCs reached equilibrium within 1 h in the equilibrator. The system was used to determine VOC partial pressures in Lake Kasumigaura, a shallow eutrophic lake with a high concentration of suspended particulate matter (SPM). Compressed air was used daily to remove SPM deposited on the inner wall of the equilibrator and to maintain the equilibrium conditions for more than a week without the need to shut the system down. CH2Br2, CHCl3, CHBrCl2, CH2BrCl, C2H5I, C2Cl4, CH3I, and CH3Br in the lake were supersaturated with respect to the air, whereas CH3CI was undersaturated. CHCl3 had the highest flux (6.2 nmol m(-2) hr(-1)) during the observation period. PMID:18754497

  18. Real-Time Monitoring of Singlet Oxygen and Oxygen Partial Pressure During the Deep Photodynamic Therapy In Vitro.

    PubMed

    Li, Weitao; Huang, Dong; Zhang, Yan; Liu, Yangyang; Gu, Yueqing; Qian, Zhiyu

    2016-09-01

    Photodynamic therapy (PDT) is an effective noninvasive method for the tumor treatment. The major challenge in current PDT research is how to quantitatively evaluate therapy effects. To our best knowledge, this is the first time to combine multi-parameter detection methods in PDT. More specifically, we have developed a set of system, including the high-sensitivity measurement of singlet oxygen, oxygen partial pressure and fluorescence image. In this paper, the detection ability of the system was validated by the different concentrations of carbon quantum dots. Moreover, the correlation between singlet oxygen and oxygen partial pressure with laser irradiation was observed. Then, the system could detect the signal up to 0.5 cm tissue depth with 660 nm irradiation and 1 cm tissue depth with 980 nm irradiation by using up-conversion nanoparticles during PDT in vitro. Furthermore, we obtained the relationship among concentration of singlet oxygen, oxygen partial pressure and tumor cell viability under certain conditions. The results indicate that the multi-parameter detection system is a promising asset to evaluate the deep tumor therapy during PDT. Moreover, the system might be potentially used for the further study in biology and molecular imaging. PMID:26833036

  19. Investigation of Copper Losses to Synthetic Slag at Different Oxygen Partial Pressures in the Presence of Colemanite

    NASA Astrophysics Data System (ADS)

    Rusen, Aydın; Derin, Bora; Geveci, Ahmet; Topkaya, Yavuz Ali

    2016-05-01

    Copper losses to slag are crucial for copper matte smelting and converting stages. One factor affecting the copper losses to slag during these processes is partial pressure of oxygen. In this study, theoretical and experimental investigations of oxygen partial pressure effect on copper losses to fayalite type slag in the presence of colemanite were investigated. Theoretical considerations include liquidus temperatures and phase diagrams of the fayalite type slag calculated by the FactSage software program. In the experiments, a synthetic matte-slag (SM-SS) was produced by melting certain amounts of reagent grade Fe2O3-SiO2 and metallic Fe as starting materials. Experiments were carried out with SM-SS pair by the addition of calcined colemanite (from 0% to 6%) under various partial pressures of oxygen (10-7, 10-9, 10-11 atm) at 1250°C for 2 h. From the experimental results, it was found that the amount of copper in slag decreased slowly when colemanite was increased under all oxidizing atmospheres. The lowest copper content in synthetic slag was obtained as 0.38% after 6% colemanite addition.

  20. Concentration Dependence of Line Shapes in the ν_1 + ν_3 Band of Acetylene

    NASA Astrophysics Data System (ADS)

    Cich, Matthew; Forthomme, Damien; Hall, Gregory; McRaven, C.; Sears, Trevor

    2014-06-01

    Using an extended cavity diode laser locked to a frequency comb, the line shape of the P(11) line in the ν_1 + ν_3 combination band of acetylene has been studied as a function of varying concentration of the absorber in nitrogen. Mixture concentrations of 1, 5 and 10% at 296 K and pressures between a few Torr and one atmosphere were made and the measurements analyzed using two different speed-dependent broadening models. These experiments are designed to test the additivity of contributions to pressure broadening and shift in speed-dependent line shape modeling, i.e. whether the lineshape parameters follow partial pressure weighting in the binary mixtures. P(11) is relatively isolated with respect to underlying hot band transitions and neighboring transitions of the same band, but it was found that the accurate positions of underlying hot band transitions were crucial to the successful modeling of the observed line shapes, even though these lines are typically 100-1000 times weaker than P(11) itself and are many Doppler line widths removed from the line center. Positions of the hot band lines quoted in the HITRAN database, which are derived from the analysis of high resolution FTIR spectra, are of the order of 10's of MHz in error. In parallel work, we have measured the positions of many of these lines by saturation dip spectroscopy. Progress in the analysis of the data and the new saturation dip line center measurements will be reported. [1] C. P. McRaven, et al. Paper RI05, 68th International Symposium on Molecular Spectroscopy, 2013 Acknowledgments: Work at Brookhaven National Laboratory was carried out under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy and supported by its Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences.

  1. The Relationship Between Oxygen Reserve Index and Arterial Partial Pressure of Oxygen During Surgery

    PubMed Central

    Dorotta, Ihab L.; Wells, Briana; Juma, David; Applegate, Patricia M.

    2016-01-01

    BACKGROUND: The use of intraoperative pulse oximetry (Spo2) enhances hypoxia detection and is associated with fewer perioperative hypoxic events. However, Spo2 may be reported as 98% when arterial partial pressure of oxygen (Pao2) is as low as 70 mm Hg. Therefore, Spo2 may not provide advance warning of falling arterial oxygenation until Pao2 approaches this level. Multiwave pulse co-oximetry can provide a calculated oxygen reserve index (ORI) that may add to information from pulse oximetry when Spo2 is >98%. This study evaluates the ORI to Pao2 relationship during surgery. METHODS: We studied patients undergoing scheduled surgery in which arterial catheterization and intraoperative arterial blood gas analysis were planned. Data from multiple pulse co-oximetry sensors on each patient were continuously collected and stored on a research computer. Regression analysis was used to compare ORI with Pao2 obtained from each arterial blood gas measurement and changes in ORI with changes in Pao2 from sequential measurements. Linear mixed-effects regression models for repeated measures were then used to account for within-subject correlation across the repeatedly measured Pao2 and ORI and for the unequal time intervals of Pao2 determination over elapsed surgical time. Regression plots were inspected for ORI values corresponding to Pao2 of 100 and 150 mm Hg. ORI and Pao2 were compared using mixed-effects models with a subject-specific random intercept. RESULTS: ORI values and Pao2 measurements were obtained from intraoperative data collected from 106 patients. Regression analysis showed that the ORI to Pao2 relationship was stronger for Pao2 to 240 mm Hg (r2 = 0.536) than for Pao2 over 240 mm Hg (r2 = 0.0016). Measured Pao2 was ≥100 mm Hg for all ORI over 0.24. Measured Pao2 was ≥150 mm Hg in 96.6% of samples when ORI was over 0.55. A random intercept variance component linear mixed-effects model for repeated measures indicated that Pao2 was significantly related to ORI

  2. Acetylenes and fatty acids from Codonopsis pilosula

    PubMed Central

    Jiang, Yueping; Liu, Yufeng; Guo, Qinglan; Jiang, Zhibo; Xu, Chengbo; Zhu, Chenggen; Yang, Yongchun; Lin, Sheng; Shi, Jiangong

    2015-01-01

    Four new acetylenes (1–4) and one new unsaturated ω-hydroxy fatty acid (5), together with 5 known analogues, were isolated from an aqueous extract of Codonopsis pilosula roots. Their structures were determined by spectroscopic and chemical methods. The new acetylenes are categorized as an unusual cyclotetradecatrienynone (1), tetradecenynetriol (2), and rare octenynoic acids (3 and 4), respectively, and 3 and 4 are possibly derived from oxidative metabolic degradation of 1 and/or 2. The absolute configuration of 1 was assigned by comparison of the experimental circular dichroism (CD) spectrum with the calculated electronic circular dichroism (ECD) spectra of stereoisomers based on the quantum-mechanical time-dependent density functional theory, while the configuration of 2 was assigned by using modified Mosher׳s method based on the MPA determination rule of ΔδRS values for diols. PMID:26579449

  3. Gd Ba Cu O bulk superconductors fabricated by a seeded infiltration growth technique under reduced oxygen partial pressure

    NASA Astrophysics Data System (ADS)

    Iida, K.; Babu, N. H.; Shi, Y. H.; Cardwell, D. A.; Murakami, M.

    2006-06-01

    Single-grain Gd-Ba-Cu-O (GdBCO) bulk superconductors have been grown by a seeded infiltration and growth (SIG) technique under a 1% O2+N2 atmosphere using a generic MgO-doped Nd-Ba-Cu-O (MgO-NdBCO) seed placed on the sample surface at room temperature (the so-called the cold-seeding method). Partial melting of the MgO-NdBCO seeds fabricated in air under notionally identical thermal processing conditions, however, limited the reliability of this bulk GdBCO single-grain process. The observed seed decomposition is attributed to the dependence of the peritectic temperature Tp of MgO-doped Nd1+xBa2-xCu3Oy solid solution (MgO-doped Nd-123ss, where ss indicates solid solution) compounds on both oxygen partial pressure during the melt process and the level of solid solution (x). The peritectic decomposition temperature of MgO-doped Nd-123ss, with x ranging from 0 to 0.5 under p(O2) = 1.00 atm, was observed to remain constant at 1120 °C. Tp was observed to decrease linearly as a function of solid solution level, on the other hand, under oxygen partial pressures of both p(O2) = 0.21 and 0.01 atm. Based on these results, MgO-doped NdBCO seed crystals should be grown under reduced oxygen partial pressure in order to obtain a stable MgO-doped NdBCO seed crystal suitable for cold-seeding processes of large-grain (RE)BCO bulk superconductors (where RE is a rare earth element).

  4. Two new acetylenic compounds from Asparagus officinalis.

    PubMed

    Li, Xue-Mei; Cai, Jin-Long; Wang, Wen-Xiang; Ai, Hong-Lian; Mao, Zi-Chao

    2016-01-01

    Two new acetylenic compounds, asparoffins A (1) and B (2), together with two known compounds, nyasol (3) and 3″-methoxynyasol (4), were isolated from stems of Asparagus officinalis. The structures of two new compounds were elucidated on the basis of detailed spectroscopic analyses (UV, IR, MS, 1D, and 2D NMR). All compounds were evaluated for their cytotoxicities against three human cancer cell lines. PMID:26558641

  5. Silver as acrolein hydrogenation catalyst: intricate effects of catalyst nature and reactant partial pressures.

    PubMed

    Bron, Michael; Teschner, Detre; Knop-Gericke, Axel; Jentoft, Friederike C; Kröhnert, Jutta; Hohmeyer, Jens; Volckmar, Claudia; Steinhauer, Bernd; Schlögl, Robert; Claus, Peter

    2007-07-21

    The hydrogenation of acrolein over pure and supported silver has been investigated with a focus on the influence of catalyst structure and reaction pressure (mbar to 20 bar range) on activity and selectivity. An onset of formation of allyl alcohol beyond 100 mbar reaction pressure (at 250 degrees C) is ascribed to a change in adsorption geometry upon increasing coverage. Smaller silver particles (in the nanometer range), the proximity of a reducible oxide component as well as high pressure lead to enhanced allyl alcohol formation; the selectivity to the other main product propionaldehyde is reduced. The silver dispersion changed depending on the reaction pressure. Moreover, the presence of oxygen, most likely as subsurface oxygen, and the presence of defects are of paramount importance for the catalytic behaviour. The considerable changes of the silver catalysts under reaction conditions and the pressure dependence call for in situ measurements to establish true structure-activity/selectivity relationships for this system. PMID:17612721

  6. Influence of N2 partial pressure on structural and microhardness properties of TiN/ZrN multilayers deposited by Ar/N2 vacuum arc discharge

    NASA Astrophysics Data System (ADS)

    Naddaf, M.; Abdallah, B.; Ahmad, M.; A-Kharroub, M.

    2016-08-01

    The influence of N2 partial pressure on structural, mechanical and wetting properties of multilayered TiN/ZrN thin films deposited on silicon substrates by vacuum arc discharge of (N2 + Ar) gas mixtures is investigated. X-ray diffraction (XRD) results show that the average texturing coefficient of (1 1 1) orientation and the grain size of both TiN and ZrN individual layers increase with increasing the N2 partial pressure. The Rutherford back scattering (RBS) measurements and analysis reveal that incorporation of the nitrogen in the film increases with increasing the N2 partial pressure and both TiN and ZrN individual layers have a nitrogen over-stoichiometry for N2 partial pressure ⩾50%. The change in the film micro-hardness is correlated to the changes in crystallographic texture, grain size, stoichiometry and the residual stress in the film as a function of the N2 partial pressure. In particular, stoichiometry of ZrN and TiN individual is found to play the vital role in determining the multilayer hardness. The multilayer film deposited at N2 partial pressure of 25% has the best stoichiometric ratio of both TiN and ZrN layers and the highest micro-hardness of about 32 GPa. In addition, water contact angle (WCA) measurements and analysis show a decrease in the work of adhesion on increasing the N2 partial pressure.

  7. Opposite influence of haloalkanes on combustion and pyrolysis of acetylene

    NASA Astrophysics Data System (ADS)

    Drakon, A. V.; Emelianov, A. V.; Eremin, A. V.; Mikheyeva, E. Yu

    2015-11-01

    An influence of haloalkanes CF3H and CCl4 (known as inflammation and explosion suppressors) on combustion and pyrolysis of acetylene behind shock waves was experimentally studied. While ignition delay times in stoihiometric acetylene-oxygen mixtures were expectedly increased by halogenoalkanes admixtures, the induction times of carbon particle formation at acetylene pyrolysis were dramatically reduced in presence of CCl4. A simplified kinetic model was suggested and characteristic rates of diacetylene C4H2 formation were estimated as a limiting stage of acetylene polymerization. An analysis of obtained data has indicated that promoting species is atomic chlorine forming in CCl4 pyrolysis, which interacts with acetylene and produces C2H radical, initiating a chain mechanism of acetylene decomposition. The results of kinetic modeling agree well with experimental data.

  8. Physical Properties of Silver Oxide Thin Film Prepared by DC Magnetron Sputtering: Effect of Oxygen Partial Pressure During Growth

    NASA Astrophysics Data System (ADS)

    Entezar Mehdi, Hamid; Hantehzadeh, M. R.; Valedbagi, Sh.

    2013-02-01

    In this paper the physical properties of silver oxide thin film have been prepared on BK7 substrate at room temperature by reactive DC magnetron sputtering technique using pure silver metal target by varying oxygen partial pressure during growth at reported. The reactive sputter gas was a mixture of Ar (99.999%) and N2 (99.999%) with the different ratio Ar and N2 by volume at the constant pressure of the growth chamber. The X-ray diffraction measurements showed that by increasing O2 volume during the Growth, change in crystalline structure will occur. The Atomic Force Microscope images shown by increasing O2 volume, the RMS roughness decreasing consistently. The thickness of the thin films decreases (from 353 to 230 nm) with increasing oxygen partial pressure in chamber. The reflectivity of thin films was investigated with a spectrophotometer system, and the surface reflectivity measurements indicate that by increasing O2 volume growth, the optical properties of the films changes.

  9. Seismic attenuation in partially saturated Berea sandstone submitted to a range of confining pressures

    NASA Astrophysics Data System (ADS)

    Chapman, Samuel; Tisato, Nicola; Quintal, Beatriz; Holliger, Klaus

    2016-03-01

    Using the forced oscillation method, we measure the extensional-mode attenuation and Young's modulus of a Berea sandstone sample at seismic frequencies (0.5-50 Hz) for varying levels of water saturation (~0-100%) and confining pressures (2-25 MPa). Attenuation is negligible for dry conditions and saturation levels <80%. For saturation levels between ~91% and ~100%, attenuation is significant and frequency dependent in the form of distinct bell-shaped curves having their maxima between 1 and 20 Hz. Increasing saturation causes an increase of the overall attenuation magnitude and a shift of its peak to lower frequencies. On the other hand, increasing the confining pressure causes a reduction in the attenuation magnitude and a shift of its peak to higher frequencies. For saturation levels above ~98%, the fluid pressure increases with increasing confining pressure. When the fluid pressure is high enough to ensure full water saturation of the sample, attenuation becomes negligible. A second series of comparable experiments reproduces these results satisfactorily. Based on a qualitative analysis of the data, the frequency-dependent attenuation meets the theoretical predictions of mesoscopic wave-induced fluid flow (WIFF) in response to a heterogeneous water distribution in the pore space, so-called patchy saturation. These results show that mesoscopic WIFF can be an important source of seismic attenuation at reservoir conditions.

  10. Formation of Complex Organics by Gas Phase and Intracluster Ion-Molecule Reactions Involving Acetylene and Hydrogen Cyanide

    NASA Astrophysics Data System (ADS)

    El-Shall, S.; Hamed, A.; Soliman, A. R.; Momoh, P. O.

    2011-05-01

    Many complex organics including polycyclic aromatic hydrocarbons are present in flames and combustion processes as well as in interstellar clouds and solar nebulae. Here, we present evidence for the formation of complex covalent organics by gas phase and intracluster reactions of the benzene, phenylium, pyridine, pyrimidine, phenylacetylene and benzonitrile cations with acetylene and hydrogen cyanide molecules. These reactions are studied using mass-selected ion mobility, chemical reactivity, collisional dissociation, and ab initio calculations. Measurements of collision cross sections in helium provide structural information on the adducts and allow probing structural changes at different temperatures (isomerization). We observed multiple additions of five acetylene molecules on the pyridine cation at room temperature. This is a remarkable result considering that only two acetylene molecules were added to the phenyl cation and no addition was observed on the benzene cation at room temperature. The experimental results are in full agreement with the ab initio calculations which predict that the first and second acetylenes add to the pyridine ion in barrierless, highly exothermic reactions. Similar reactions have been observed for the pyrimidine radical cation although the extent of the addition reactions is limited to only two acetylene molecules at room temperature. The results provide the first evidence for the incorporation of nitrogen in the formation cyclic hydrocarbons via the gas phase reactions of pyridine and pyrimidine ions with acetylene molecules. In addition, the formation of covalent adducts in the ionized acetylene/HCN system will be reported for the first time. Sequential reactions leading to the formation of pyridine and pyrimidine radical cations and higher adducts are observed over a wide range of temperature and pressure. The formation of these covalent adducts may represent a general class of addition reactions that can form complex

  11. Seed storage at elevated partial pressure of oxygen, a fast method for analysing seed ageing under dry conditions

    PubMed Central

    Groot, S. P. C.; Surki, A. A.; de Vos, R. C. H.; Kodde, J.

    2012-01-01

    Background and Aims Despite differences in physiology between dry and relative moist seeds, seed ageing tests most often use a temperature and seed moisture level that are higher than during dry storage used in commercial practice and gene banks. This study aimed to test whether seed ageing under dry conditions can be accelerated by storing under high-pressure oxygen. Methods Dry barley (Hordeum vulgare), cabbage (Brassica oleracea), lettuce (Lactuca sativa) and soybean (Glycine max) seeds were stored between 2 and 7 weeks in steel tanks under 18 MPa partial pressure of oxygen. Storage under high-pressure nitrogen gas or under ambient air pressure served as controls. The method was compared with storage at 45 °C after equilibration at 85 % relative humidity and long-term storage at the laboratory bench. Germination behaviour, seedling morphology and tocopherol levels were assessed. Key Results The ageing of the dry seeds was indeed accelerated by storing under high-pressure oxygen. The morphological ageing symptoms of the stored seeds resembled those observed after ageing under long-term dry storage conditions. Barley appeared more tolerant of this storage treatment compared with lettuce and soybean. Less-mature harvested cabbage seeds were more sensitive, as was the case for primed compared with non-primed lettuce seeds. Under high-pressure oxygen storage the tocopherol levels of dry seeds decreased, in a linear way with the decline in seed germination, but remained unchanged in seeds deteriorated during storage at 45 °C after equilibration at 85 % RH. Conclusions Seed storage under high-pressure oxygen offers a novel and relatively fast method to study the physiology and biochemistry of seed ageing at different seed moisture levels and temperatures, including those that are representative of the dry storage conditions as used in gene banks and commercial practice. PMID:22967856

  12. Temperature measurements of partially-melted tin as a function of shock pressure

    SciTech Connect

    Seifter, Achim; Furlanetto, Michael R; Holtkamp, David B; Obst, Andrew W; Payton, J R; Stone, J B; Tabaka, L J; Grover, M; Macrum, G; Stevens, G D; Swift, D C; Turley, W D; Veeser, L R

    2009-01-01

    Equilibrium equation of state theory predicts that the free surface release temperature of shock loaded tin will show a plateau of 505 K in the pressure range from 19.5 to 33.0 GPa, corresponding to the solid-liquid mixed-phase region. In this paper we report free surface temperature measurements on shock-loaded tin from 15 to 31 GPa using multi-wavelength optical pyrometry. The shock waves were generated by direct contact of detonating high explosive with the sample. The pressure in the sample was determined by free surface velocity measurements using Photon Doppler Velocimetry. The emitted thermal radiance was measured at four wavelength bands in the near IR region from 1.5 to 5.0 {micro}m. The samples in most of the experiments had diamond-turned surface finishes, with a few samples being polished or ball rolled. At pressures higher than 25 GPa the measured free surface temperatures were higher than the predicted 505 K and increased with increasing pressure. This deviation could be explained by hot spots and/or variations in surface emissivity and requires a further investigation.

  13. Investigation of NH3 input partial pressure for N-polarity InGaN growth on GaN substrates by tri-halide vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    Hirasaki, Takahide; Hasegawa, Tomoyasu; Meguro, Misaki; Thieu, Quang Tu; Murakami, Hisashi; Kumagai, Yoshinao; Monemar, Bo; Koukitu, Akinori

    2016-05-01

    The influence of NH3 input partial pressure on N-polarity InGaN grown by tri-halide vapor phase epitaxy was investigated. It was found that surface morphology, solid composition and optical properties were affected by NH3 input partial pressure. As shown in thermodynamic analyses, the indium content increased due to an increase in the driving force for InN deposition caused by increased NH3 input partial pressure. In addition, the deep level emission around 2.1 eV in photoluminescence measurements drastically decreased at higher NH3 input partial pressures. Ab initio calculations and subsequent secondary ion mass spectrometry measurements suggested the reduction of metal-vacancies and/or carbon impurity incorporation in the InGaN layers.

  14. On the influence of the hysteretic behavior of the capillary pressure on the wave propagation in partially saturated soils

    NASA Astrophysics Data System (ADS)

    Albers, Bettina

    2016-06-01

    It is well known that the capillary pressure curve of partially saturated soils exhibits a hysteresis. For the same degree of saturation it has different values depending on the initial state of the soil, thus for drying of a wet soil or wetting of a dry soil. The influence of these different values of the capillary pressure on the propagation of sound waves is studied by use of a linear hyperbolic model. Even if the model does not contain a hysteresis operator, the effect of hysteresis in the capillary pressure curve is accounted for. In order to obtain the limits of phase speeds and attenuations for the two processes the correspondent values for main drying and main wetting are inserted into the model separately. This is done for two examples of soils, namely for Del Monte sand and for a silt loam both filled by an air-water mixture. The wave analysis reveals four waves: one transversal wave and three longitudinal waves. The waves which are driven by the immiscible pore fluids are influenced by the hysteresis in the capillary pressure curve while the waves which are mainly driven by the solid are not.

  15. High-Pressure Synthesis of Manganese Oxyhydride with Partial Anion Order.

    PubMed

    Tassel, Cedric; Goto, Yoshinori; Watabe, Daichi; Tang, Ya; Lu, Honcheng; Kuno, Yoshinori; Takeiri, Fumitaka; Yamamoto, Takafumi; Brown, Craig M; Hester, James; Kobayashi, Yoji; Kageyama, Hiroshi

    2016-08-01

    The high-pressure synthesis of a manganese oxyhydride LaSrMnO3.3 H0.7 is reported. Neutron and X-ray Rietveld analyses showed that this compound adopts the K2 NiF4 structure with hydride ions positioned exclusively at the equatorial site. This result makes a striking contrast to topochemical reductions of LaSrMnO4 that result in only oxygen-deficient phases down to LaSrMnO3.5 . This suggests that high H2 pressure plays a key role in stabilizing the oxyhydride phase, offering an opportunity to synthesize other transition-metal oxyhydrides. Magnetic susceptibility revealed a spin-glass transition at 24 K that is due to competing ferromagnetic (Mn(2+) -Mn(3+) ) and antiferromagnetic (Mn(2+) -Mn(2) , Mn(3+) -Mn(3+) ) interactions. PMID:27355695

  16. The CO2 stimulus for cerebrovascular reactivity: Fixing inspired concentrations vs. targeting end-tidal partial pressures.

    PubMed

    Fisher, Joseph A

    2016-06-01

    Cerebrovascular reactivity (CVR) studies have elucidated the physiology and pathophysiology of cerebral blood flow regulation. A non-invasive, high spatial resolution approach uses carbon dioxide (CO2) as the vasoactive stimulus and magnetic resonance techniques to estimate the cerebral blood flow response. CVR is assessed as the ratio response change to stimulus change. Precise control of the stimulus is sought to minimize CVR variability between tests, and show functional differences. Computerized methods targeting end-tidal CO2 partial pressures are precise, but expensive. Simpler, improvised methods that fix the inspired CO2 concentrations have been recommended as less expensive, and so more widely accessible. However, these methods have drawbacks that have not been previously presented by those that advocate their use, or those that employ them in their studies. As one of the developers of a computerized method, I provide my perspective on the trade-offs between these two methods. The main concern is that declaring the precision of fixed inspired concentration of CO2 is misleading: it does not, as implied, translate to precise control of the actual vasoactive stimulus - the arterial partial pressure of CO2 The inherent test-to-test, and therefore subject-to-subject variability, precludes clinical application of findings. Moreover, improvised methods imply widespread duplication of development, assembly time and costs, yet lack uniformity and quality control. A tabular comparison between approaches is provided. PMID:27000209

  17. Growth of MoO3 nanostructured thin films as a function of O2-partial pressure

    NASA Astrophysics Data System (ADS)

    Sharma, Rabindar Kumar; Kumar, Prabhat; Reddy, G. B.

    2015-06-01

    In this report, we synthesized molybdenum trioxide (α-MoO3) nanostructured thin films (NSTs) with nanoflakes (NFs) on the Ni-coated glass substrates employing plasma assisted sublimation process (PASP) as a function of oxygen partial pressure (PO2). The effect of oxygen partial pressure on structural, morphological, and vibrational properties have been investigated systematically. The structural analysis divulged that all films deposited at different PO2 have pure orthorhombic phase, no impurity phase is detected under the limit of resolution. The morphological studies of samples is carried out by SEM, revealed that features as well as alignment of MoO3 NSTs can be monitored by PO2 and the sample having best features is obtained at 7.5×10-2 Torr. In addition, the more insight information is accomplished by TEM/HRTEM on the best featured sample, which confirmed the single crystalline nature of nanoflakes. The vibrational study of all samples are performed by FTIR, and strongly supports the XRD observations. All the results are in consonance with each other.

  18. Laser-induced damage threshold of ZrO{sub 2} thin films prepared at different oxygen partial pressures by electron-beam evaporation

    SciTech Connect

    Zhang Dongping; Shao Jianda; Zhao Yuanan; Fan Shuhai; Hong Ruijing; Fan Zhengxiu

    2005-01-01

    ZrO{sub 2} films were deposited by electron-beam evaporation with the oxygen partial pressure varying from 3x10{sup -3} Pa to 11x10{sup -3} Pa. The phase structure of the samples was characterized by x-ray diffraction (XRD). The thermal absorption of the films was measured by the surface thermal lensing technique. A spectrophotometer was employed to measure the refractive indices of the samples. The laser-induced damage threshold (LIDT) was assessed using a 1064 nm Nd: yttritium-aluminum-garnet pulsed laser at pulse width of 12 ns. The influence of oxygen partial pressure on the microstructure and LIDT of ZrO{sub 2} films was investigated. XRD data revealed that the films changed from polycrystalline to amorphous as the oxygen partial pressure increased. The variation of refractive index at 550 nm wavelength indicated that the packing density of the films decreased gradually with increasing oxygen partial pressure. The absorptance of the samples decreased monotonically from 125.2 to 84.5 ppm with increasing oxygen partial pressure. The damage threshold values increased from 18.5 to 26.7 J/cm{sup 2} for oxygen partial pressures varying from 3x10{sup -3} Pa to 9x10{sup -3} Pa, but decreased to 17.3 J/cm{sup 2} in the case of 11x10{sup -3} Pa.

  19. RECRYSTALLIZATION OF PMDA AND SYNTHESIS OF AN ACETYLENIC DIAMINE

    SciTech Connect

    Sanner, R; Cook, R C

    2004-09-21

    This memo provides documentation for the method of recrystallization of pyromeletic dianhydride (PMDA), the dianhydride used in the vapor deposition of Kapton-like polyimide for ICF shell ablators and for the synthesis of bis(3-aminophenyl) acetylene, a unique acetylenic diamine developed for vapor deposition testing.

  20. 76 FR 75782 - Revising Standards Referenced in the Acetylene Standard

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-05

    ... standards that reference or include language from outdated standards published by standards developing organizations (``SDO standards'') (69 FR 68283). A SDO standard referenced in OSHA's Acetylene Standard (29 CFR... of the Compressed Gas Association standard, CGA G-1-2003, in the Acetylene Standard. See 74 FR...

  1. Proton exchange membrane fuel cell cathode contamination - Acetylene

    NASA Astrophysics Data System (ADS)

    Zhai, Y.; St-Pierre, Jean

    2015-04-01

    Acetylene adsorption on PEMFC electrodes and contamination in single cells are investigated with 300 ppm acetylene at a cathode held at 80 °C. The results of adsorption experiments suggest that acetylene adsorbs readily on electrodes and is reduced to ethylene and ethane under an open circuit potential of H2/N2, as the adsorbates can be electro-oxidized at high potentials. The cell voltage response shows that 300 ppm acetylene results in a cell performance loss of approximately 88%. The voltage degradation curve is divided into two stages by an inflection point, which suggests that potential-dependent processes are involved in acetylene poisoning. These potential-dependent processes may include acetylene oxidation and reduction as well as accumulation of intermediates on the electrode surface. Electrochemical impedance spectroscopy analysis suggests that acetylene affects the oxygen reduction reaction and may also affect mass transport processes. Acetylene also may be reduced in the steady poisoning state of the operating cell. After neat air operation, the cyclic voltammetry results imply that the cathode catalyst surface is almost completely restored, with no contaminant residues remaining in the MEA. Linear scanning voltammetry measurements show no change in hydrogen crossover caused by contamination, and polarization curves confirm complete recovery of cell performance.

  2. Acetylene-based chemicals from coal and other natural resources

    SciTech Connect

    Tedeschi, R.J.

    1982-01-01

    The economic and technological changes which have affected acetylene directly are examined. Commodity chemicals, which were manufactured from acetylene more than thirty years ago, are now made almost entirely from hydrocarbons such as ethylene, propylene, or butadiene. During this period, calcium carbide acetylene was displaced by petrochemical acetylene, the latter was gradually displaced by less expensive olefins and alkanes. The calcium carbide process viewed in terms of its abundant raw materials, might again become an attractive technology as petroleum-based feedstocks become scarcer and more expensive. With improved furnace design and solids handling, further economics in this process may be possible. The greatest growth area for acetylene is now in Reppe-type chemicals such as butyndiol, tetrahydrofuran, N-methyl-2-pyrrolidone, vinyl pyrrolidone, and polyvinyl pyrrolidone, and a variety of acetylenic alcohols and glycols. The technology and applications for large-volume acetylenic products and their derivatives are outlined. Acetylene production processes purification, stability and guidelines for its safe use in chemical operations are described. 327 references, 30 figures, 19 tables.

  3. Acetylene-Based Materials in Organic Photovoltaics

    PubMed Central

    Silvestri, Fabio; Marrocchi, Assunta

    2010-01-01

    Fossil fuel alternatives, such as solar energy, are moving to the forefront in a variety of research fields. Organic photovoltaic systems hold the promise of a lightweight, flexible, cost-effective solar energy conversion platform, which could benefit from simple solution-processing of the active layer. The discovery of semiconductive polyacetylene by Heeger et al. in the late 1970s was a milestone towards the use of organic materials in electronics; the development of efficient protocols for the palladium catalyzed alkynylation reactions and the new conception of steric and conformational advantages of acetylenes have been recently focused the attention on conjugated triple-bond containing systems as a promising class of semiconductors for OPVs applications. We review here the most important and representative (poly)arylacetylenes that have been used in the field. A general introduction to (poly)arylacetylenes, and the most common synthetic approaches directed toward making these materials will be firstly given. After a brief discussion on working principles and critical parameters of OPVs, we will focus on molecular arylacetylenes, (co)polymers containing triple bonds, and metallopolyyne polymers as p-type semiconductor materials. The last section will deal with hybrids in which oligomeric/polymeric structures incorporating acetylenic linkages such as phenylene ethynylenes have been attached onto C60, and their use as the active materials in photovoltaic devices. PMID:20480031

  4. Chemistry of polycyclic aromatic hydrocarbons formation from phenyl radical pyrolysis and reaction of phenyl and acetylene.

    PubMed

    Comandini, A; Malewicki, T; Brezinsky, K

    2012-03-15

    An experimental investigation of phenyl radical pyrolysis and the phenyl radical + acetylene reaction has been performed to clarify the role of different reaction mechanisms involved in the formation and growth of polycyclic aromatic hydrocarbons (PAHs) serving as precursors for soot formation. Experiments were conducted using GC/GC-MS diagnostics coupled to the high-pressure single-pulse shock tube present at the University of Illinois at Chicago. For the first time, comprehensive speciation of the major stable products, including small hydrocarbons and large PAH intermediates, was obtained over a wide range of pressures (25-60 atm) and temperatures (900-1800 K) which encompass the typical conditions in modern combustion devices. The experimental results were used to validate a comprehensive chemical kinetic model which provides relevant information on the chemistry associated with the formation of PAH compounds. In particular, the modeling results indicate that the o-benzyne chemistry is a key factor in the formation of multi-ring intermediates in phenyl radical pyrolysis. On the other hand, the PAHs from the phenyl + acetylene reaction are formed mainly through recombination between single-ring aromatics and through the hydrogen abstraction/acetylene addition mechanism. Polymerization is the common dominant process at high temperature conditions. PMID:22339468

  5. Highly oriented NdFeCoB nanocrystalline magnets from partially disproportionated compacts by reactive deformation under low pressure

    SciTech Connect

    Zheng, Qing; Li, Jun; Liu, Ying Yu, Yunping; Lian, Lixian

    2014-05-07

    In the present investigation, we take advantage of the ultrafine grain size of NdFeCoB partially hydrogen-disproportionated phases, and prepare anisotropic nanocrystalline magnets with full density and homogenous microstructure and texture by reactive deformation under low pressure. Our results suggest that the pressure could properly promote an occurrence of desorption-recombination reaction due to a shorter-range rearrangement of the atoms, and the newly recombined Nd{sub 2}Fe{sub 14}B grains with fine grain size could undergo deformation immediately after the phase transformation, and then an obvious anisotropy and uniform alignment would be obtained. The maximum magnetic properties, (BH){sub max} = 25.8 MGOe, Br = 11.8 kG, H{sub cj} = 5.5 kOe, were obtained after being treated for 5 min at 820 °C in vacuum. The present study highlights the feasibility to prepare anisotropic nanocrystalline magnets with homogeneous microstructure and a strong (00l) texture of uniform grain size under low pressure.

  6. Brain tissue partial pressure of oxygen predicts the outcome of severe traumatic brain injury under mild hypothermia treatment

    PubMed Central

    Sun, Hongtao; Zheng, Maohua; Wang, Yanmin; Diao, Yunfeng; Zhao, Wanyong; Wei, Zhengjun

    2016-01-01

    Objective The aim of this study was to investigate the clinical significance and changes of brain tissue partial pressure of oxygen (PbtO2) in the course of mild hypothermia treatment (MHT) for treating severe traumatic brain injury (sTBI). Methods There were 68 cases with sTBI undergoing MHT. PbtO2, intracranial pressure (ICP), jugular venous oxygen saturation (SjvO2), and cerebral perfusion pressure (CPP) were continuously monitored, and clinical outcomes were evaluated using the Glasgow Outcome Scale score. Results Of 68 patients with sTBI, PbtO2, SjvO2, and CPP were obviously increased, but decreased ICP level was observed throughout the MHT. PbtO2 and ICP were negatively linearly correlated, while there was a positive linear correlation between PbtO2 and SjvO2. Monitoring CPP and SjvO2 was performed under normal circumstances, and a large proportion of patients were detected with low PbtO2. Decreased PbtO2 was also found after MHT. Conclusion Continuous PbtO2 monitoring could be introduced to evaluate the condition of regional cerebral oxygen metabolism, thereby guiding the clinical treatment and predicting the outcome. PMID:27601907

  7. Partial Gene Deletions of PMP22 Causing Hereditary Neuropathy with Liability to Pressure Palsies

    PubMed Central

    Cho, Sun-Mi; Kim, Yoonjung; Lee, Sang Guk; Yang, Jin-Young

    2014-01-01

    Hereditary neuropathy with liability to pressure palsies (HNPP) is an autosomal neuropathy that is commonly caused by a reciprocal 1.5 Mb deletion on chromosome 17p11.2, at the site of the peripheral myelin protein 22 (PMP22) gene. Other patients with similar phenotypes have been shown to harbor point mutations or small deletions, although there is some clinical variation across these patients. In this report, we describe a case of HNPP with copy number changes in exon or promoter regions of PMP22. Multiplex ligation-dependent probe analysis revealed an exon 1b deletion in the patient, who had been diagnosed with HNPP in the first decade of life using molecular analysis. PMID:25506001

  8. Partial Gene Deletions of PMP22 Causing Hereditary Neuropathy with Liability to Pressure Palsies.

    PubMed

    Cho, Sun-Mi; Hong, Bo Young; Kim, Yoonjung; Lee, Sang Guk; Yang, Jin-Young; Kim, Juwon; Lee, Kyung-A

    2014-01-01

    Hereditary neuropathy with liability to pressure palsies (HNPP) is an autosomal neuropathy that is commonly caused by a reciprocal 1.5 Mb deletion on chromosome 17p11.2, at the site of the peripheral myelin protein 22 (PMP22) gene. Other patients with similar phenotypes have been shown to harbor point mutations or small deletions, although there is some clinical variation across these patients. In this report, we describe a case of HNPP with copy number changes in exon or promoter regions of PMP22. Multiplex ligation-dependent probe analysis revealed an exon 1b deletion in the patient, who had been diagnosed with HNPP in the first decade of life using molecular analysis. PMID:25506001

  9. Partial amorphization of a Cu-Zr-Ti alloy by high pressure torsion

    SciTech Connect

    Revesz, Adam; Hobor, Sandor; Labar, Janos L.; Zhilyaev, Alex P.; Kovacs, Zsolt

    2006-11-15

    High pressure torsion was applied to produce disk-shape specimen of Cu{sub 60}Zr{sub 20}Ti{sub 20} composition. Radial dependence of the microstructure was monitored by x-ray diffraction, scanning, and transmission electron microscopies. The disk consists of a top surface layer, homogeneous on a micrometer scale with an average thickness of 10-20 {mu}m, and an inhomogeneous bulk region of 200 {mu}m thickness. Calorimetric studies revealed that the disk contains detectable amount of amorphous phase. Characteristics of this amorphous content were compared to a fully amorphous melt-quenched Cu{sub 60}Zr{sub 20}Ti{sub 20} ribbon.

  10. An autopsy case of suicide by acetylene explosion: a case report.

    PubMed

    Kashiwagi, Masayuki; Hara, Kenji; Takamoto, Mutsuo; Kageura, Mitsuyoshi; Matsusue, Aya; Sugimura, Tomoko; Kubo, Shin-ichi

    2009-04-01

    We report an autopsy case of a male welder in his thirties who was found dead in an exploded truck cabin. The roof, windows and doors of the cabin had been blown up to 50 metres away. An oxygen cylinder and an acetylene cylinder, both unexploded, were found in the back of the truck. The deceased was lying on the driver's seat. His entire body was burnt, carbonised and partially skeletonised. There was a small amount of soot in his oesophagus and stomach and a large volume of bloody fluid in the trachea and bronchi. There was an extensive haemorrhage in the posterior thoracic wall. No drugs were detected in the blood. Hardly any carbon monoxide and combustion-related gases were detected in the blood, therefore he was not considered to have died from the fire. Acetylene was detected in his blood (21.5 microg/ml in the femoral vein blood) and urine (7.49 microg/ml), with marked haemorrhaging in his back. We therefore concluded that the victim died because of an acetylene explosion in the cabin and also that this was a suicide. PMID:19537452

  11. Structural, mechanical, electrical and wetting properties of ZrNx films deposited by Ar/N2 vacuum arc discharge: Effect of nitrogen partial pressure

    NASA Astrophysics Data System (ADS)

    Abdallah, B.; Naddaf, M.; A-Kharroub, M.

    2013-03-01

    Non-stiochiometric zirconium nitride (ZrNx) thin films have been deposited on silicon substrates by vacuum arc discharge of (N2 + Ar) gas mixtures at different N2 partial pressure ratio. The microstructure, mechanical, electrical and wetting properties of these films are studied by means of X-ray diffraction (XRD), micro-Raman spectroscopy, Rutherford back scattering (RBS) technique, conventional micro-hardness testing, electrical resistivity, atomic force microscopy (AFM) and contact angle (CA) measurements. RBS results and analysis show that the (N/Zr) ratio in the film increases with increasing the N2 partial pressure. A ZrNx film with (Zr/N) ratio in the vicinity of stoichiometric ZrN is obtained at N2 partial pressure of 10%. XRD and Raman results indicate that all deposited films have strained cubic crystal phase of ZrN, regardless of the N2 partial pressure. On increasing the N2 partial pressure, the relative intensity of (1 1 1) orientation with respect to (2 0 0) orientation is seen to decrease. The effect of N2 partial pressure on micro-hardness and the resistivity of the deposited film is revealed and correlated to the alteration of grain size, crystallographic texture, stoichiometry and residual stress developed in the film. In particular, it is found that residual stress and nitrogen incorporation in the film play crucial role in the alteration of micro-hardness and resistivity respectively. In addition, CA and AFM results demonstrate that as N2 partial pressure increases, both the surface hydrophobicity and roughness of the deposited film increase, leading to a significant decrease in the film surface free energy (SFE).

  12. Oxidation behavior of V-Cr-Ti alloys in low-partial-pressure oxygen environments

    SciTech Connect

    Natesan, K.; Uz, M.

    1998-09-01

    A test program is in progress at Argonne National Laboratory to evaluate the effect of pO{sub 2} in the exposure environment on oxygen uptake, scaling kinetics, and scale microstructure in V-Cr-Ti alloys. The data indicate that the oxidation process follows parabolic kinetics in all of the environments used in the present study. From the weight change data, parabolic rate constants were evaluated as a function of temperature and exposure environment. The temperature dependence of the parabolic rate constants was described by an Arrhenius relationship. Activation energy for the oxidation process was fairly constant in the oxygen pressure range of 1 {times} 10{sup {minus}6} to 1 {times} 10{sup {minus}1} torr for both the alloys. The activation energy for oxidation in air was significantly lower than in low-pO{sub 2} environments, and for oxidation in pure O{sub 2} at 760 torr was much lower than in low-pO{sub 2} environments. X-ray diffraction analysis of the specimens showed that VO{sub 2} was the dominant phase in low-pO{sub 2} environments, while V{sub 2}O{sub 5} was dominant in air and in pure oxygen at 76f0 torr.

  13. The electrochemical behaviour of 316L austenitic stainless steel in Cl- containing environment under different H2S partial pressures

    NASA Astrophysics Data System (ADS)

    Ding, Jinhui; Zhang, Lei; Lu, Minxu; Wang, Jing; Wen, Zhibin; Hao, Wenhui

    2014-01-01

    In oil-gas production environments, presence of H2S-Cl- can induce deterioration of the passive film, leading to pitting corrosion of stainless steels. In this paper, by using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and capacitance measurements (Mott-Schottky analysis), the electrochemical behaviour of AISI 316L austenitic stainless steel was investigated in Cl- solutions under different H2S partial pressures (from 0 to 1.0 bar). The results indicated that presence of H2S in Cl- solution can accelerate both the cathodic and anodic current density, leading to a metastable passive state in higher passive potential range, changing the semiconductor behaviour from p-type to n-type, increasing its susceptibility to corrosion. XPS analysis was employed to characterize the surface film after potentiostatic polarization, whose results provide good evidences for the electrochemical measurements.

  14. Equilibrium partial pressure of CO2 in Callovian-Oxfordian argillite as a function of relative humidity: Experiments and modelling

    NASA Astrophysics Data System (ADS)

    Lassin, Arnault; Marty, Nicolas C. M.; Gailhanou, Hélène; Henry, Benoît; Trémosa, Joachim; Lerouge, Catherine; Madé, Benoît; Altmann, Scott; Gaucher, Eric C.

    2016-08-01

    Having previously demonstrated that the mineral assemblage of claystone can impose its pCO2 under saturated conditions, we here study the effect of rock desaturation, i.e. the evaporation of pore water, on the partial pressure of CO2 (pCO2) in Callovian-Oxfordian argillite from the Paris Basin (France). In this new study, which combines experiments at room temperature and geochemical modelling, we examine the primary role of capillary forces on chemical equilibria for relative humidity values ranging between 50% and 100%. In particular we are able, without any fitting parameters, to model the experimental decrease of pCO2 as a function of decreasing water content in the argillite. This application to a complex natural system not only confirms the theoretical concepts of geochemistry in capillary contexts, but is promising with respect to other systems, both natural (soil, rock) and industrial (ceramics, granular material).

  15. Oxygen partial pressure dependent optical properties of glancing angle deposited (GLAD) Ta2O5 films deposited by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Tripathi, S.; Haque, S. Maidul; Rao, K. Divakar; Misal, J. S.; Pratap, C.; Sahoo, N. K.

    2016-05-01

    Experiments were carried out on Ta2O5 oxide thin films by asymmetric bipolar pulsed DC magnetron sputtering using a new hybrid combination of conventional (normal incidence) deposition and glancing angle deposition (GLAD) geometries. The films were prepared with varying O2 partial pressure. The ellipsometry characterization reveals a systematic variation in refractive index, which decreased from 2.2 in the normal films to an average 1.78 in the GLAD films. The bandgap of these GLAD films is slightly higher as compared to normal films. Overall transmission of the GLAD films is increased is by ~ 15 % implying a reduction in the refractive index for potential optical filtering device applications. The results were further supported by X-ray reflectivity measurements which show an effective double layer structure in GLAD consisting of layers with different densities of the same Ta2O5 material.

  16. Influence of Ca content and oxygen partial pressure on microstructural evolution of (Co,Ca)O at elevated temperatures.

    PubMed

    Kusinski, J; Cieniek, L; Petot-Ervas, G; Petot, C; Baldinozzi, G

    2006-10-01

    Ca-doped (1, 1.7, 5 and 10 mol% CaO) cobalt oxide single-crystal samples, with an [001] orientation, were annealed at elevated temperatures of 1000-1200 degrees C for different times and at different oxygen partial pressures. The microstructure was examined by means of transmission light and electron microscopy. High-temperature X-ray diffractometry was used, with the aim of determining the temperature of the CoO <--> Co(3)O(4) transition in these materials. Extensive precipitation of Ca-free Co(3)O(4) spinel crystals was observed with increasing Ca content and oxygen activity. It is suggested that the electrical conductivity changes in this material may be related to this precipitation, because it changes the electronic state of cobalt cations. PMID:17100900

  17. Aldehydes in hydrothermal solution - Standard partial molal thermodynamic properties and relative stabilities at high temperatures and pressures

    NASA Technical Reports Server (NTRS)

    Schulte, Mitchell D.; Shock, Everett L.

    1993-01-01

    Aldehydes are common in a variety of geologic environments and are derived from a number of sources, both natural and anthropogenic. Experimental data for aqueous aldehydes were taken from the literature and used, along with parameters for the revised Helgeson-Kirkham-Flowers (HKF) equations of state, to estimate standard partial molal thermodynamic data for aqueous straight-chain alkyl aldehydes at high temperatures and pressures. Examples of calculations involving aldehydes in geological environments are given, and the stability of aldehydes relative to carboxylic acids is evaluated. These calculations indicate that aldehydes may be intermediates in the formation of carboxylic acids from hydrocarbons in sedimentary basin brines and hydrothermal systems like they are in the atmosphere. The data and parameters summarized here allow evaluation of the role of aldehydes in the formation of prebiotic precursors, such as amino acids and hydroxy acids on the early Earth and in carbonaceous chondrite parent bodies.

  18. Growth of GaAs from a free surface melt under controlled arsenic pressure in a partially confined configuration

    NASA Technical Reports Server (NTRS)

    Gatos, H. C.; Lagowski, J.; Wu, Y.

    1988-01-01

    A partially confined configuration for the growth of GaAs from melt in space was developed, consisting of a triangular prism containing the seed crystal and source material in the form of a rod. It is suggested that the configuration overcomes two obstacles in the growth of GaAs in space: total confinement in a quartz crucible and lack of arsenic pressure control. Ground tests of the configuration show that it is capable of crystal growth in space and is useful for studying the growth of GaAs from a free-surface melt on earth. The resulting chemical composition, electrical property variations, and phenomenological models to account for the results are presented.

  19. Correlation Between Partial Pressure of Arterial Carbon Dioxide and End Tidal Carbon Dioxide in Patients with Severe Alcohol Withdrawal

    PubMed Central

    Yousuf, Tariq; Brinton, Taylor; Kramer, Jason; Khan, Basharath; Ziffra, Jeffrey; Villines, Dana; Shah, Poorvi; Hanif, Tabassum

    2015-01-01

    Background Respiratory depression is a common adverse effect of benzodiazepine administration to patients with severe alcoholic withdrawal. This study was conducted to assess the value of end tidal carbon dioxide (ETCO2) levels compared to partial pressure of arterial carbon dioxide (PaCO2) levels in monitoring respiratory depression secondary to benzodiazepine treatment in patients with severe alcohol withdrawal. Methods We retrospectively analyzed 36 patients admitted to the intensive care unit for severe alcohol withdrawal who had been administered sedative agents. Results We observed a statistically significant correlation between PaCO2 and ETCO2 at time 1 (r=0.74, P<0.01) and time 3 (r=0.52, P=0.02) but not at time 2 (r=0.22, P=0.31). Conclusion Our study confirms a positive correlation between PaCO2 and ETCO2 levels in patients experiencing severe alcohol withdrawal. PMID:26730226

  20. Aldehydes in hydrothermal solution: Standard partial molal thermodynamic properties and relative stabilities at high temperatures and pressures

    SciTech Connect

    Schulte, M.D.; Shock, E.L. )

    1993-08-01

    Aldehydes are common in a variety of geologic environments and are derived from a number of sources, both natural and anthropogenic. Experimental data for aqueous aldehydes were taken from the literature and used, along with parameters for the revised Helgeson-Kirkham-Flowers (HKF) equations of state, to estimate standard partial molal thermodynamic data for aqueous straight-chain alkyl aldehydes at high temperatures and pressures. Examples of calculations involving aldehydes in geological environments are given, and the stability of aldehydes relative to carboxylic acids is evaluated. These calculations indicate that aldehydes may be intermediates in the formation of carboxylic acids from hydrocarbons in sedimentary basins brines and hydrothermal systems like they are in the atmosphere. The data and parameters summarized here allow evaluation of the role of aldehydes in the formation of prebiotic precursors, such as amino acids and hydroxy acids on the early Earth and in carbonaceous chondrite parent bodies. 97 refs., 5 figs., 3 tabs.

  1. Effect of oxygen partial pressure on superconducting properties of Bi-2212/Ag tapes prepared by doctor-blade method

    SciTech Connect

    Inoue, N.; Okada, M.; Higashiyama, K.

    1997-06-01

    The authors have investigated the relationship between oxygen partial pressure (P{sub O{sub 2}}) during the partial-melting process and superconducting properties for doctor-blade processed Bi-2212/Ag tapes. Tapes were heat-treated at various P{sub O{sub 2}} value of 0.01-1.00 atm. The DTA results for the doctor-blade tapes showed the melting point of the oxide rose with increasing P{sub O{sub 2}}. Correspondingly, the optimum heat-treatment temperature also increased with increasing P{sub O{sub 2}}. The tapes at P{sub O{sub 2}}=1.00 atm had the highest J{sub c} values of over 10{sup 5} A/cm{sup 2} at conditions of 4.2K, 10T, and their a.c. susceptibility showed a sharp transition indicating improved intergrain coupling. Examination of cross sections for tapes melted above 0.20atm PO{sub 2} showed the good crystal alignment. From these results, it was concluded that processing at high PO{sub 2} was an effective method to obtain good superconducting properties for doctor-blade tapes.

  2. Experimental determination of carbonation rate in Portland cement at 25°C and relatively high CO2 partial pressure

    NASA Astrophysics Data System (ADS)

    Hernández-Rodríguez, Ana; Montegrossi, Giordano; Huet, Bruno; Virgili, Giorgio; Orlando, Andrea; Vaselli, Orlando; Marini, Luigi

    2016-04-01

    The aim of this work is to study the alteration of Portland class G Cement at ambient temperature under a relatively high CO2 partial pressure through suitably designed laboratory experiments, in which cement hydration and carbonation are taken into account separately. First, the hydration process was carried out for 28 days to identify and quantify the hydrated solid phases formed. After the completion of hydration, accompanied by partial carbonation under atmospheric conditions, the carbonation process was investigated in a stirred micro-reactor (Parr instrument) with crushed cement samples under 10 bar or more of pure CO2(g) and MilliQ water adopting different reaction times. The reaction time was varied to constrain the reaction kinetics of the carbonation process and to investigate the evolution of secondary solid phases. Chemical and mineralogical analyses (calcimetry, chemical composition, SEM and X-ray Powder Diffraction) were carried out to characterize the secondary minerals formed during cement hydration and carbonation. Water analyses were also performed at the end of each experimental run to measure the concentrations of relevant solutes. The specific surface area of hydrated cement was measured by means of the BET method to obtain the rates of cement carbonation. Experimental outcomes were simulated by means of the PhreeqC software package. The obtained results are of interest to understand the comparatively fast cement alteration in CO2 production wells with damaged casing.

  3. Acetylene-chromene terminated resins as high temperature thermosets

    NASA Technical Reports Server (NTRS)

    Godschalx, J. P.; Inbasekaran, M. N.; Bartos, B. R.; Scheck, D. M.; Laman, S. A.

    1990-01-01

    A novel phase transfer catalyzed process for the preparation of propargyl ethers has been developed. The propargyl ethers serve as precursors to a new class of thermosetting resins called acetylene-chromene terminated (ACT) resins. Heat treatment of a solution of propargyl ethers with various catalysts, followed by removal of solvent leads to the ACT resins via partial conversion of the propargyl ether groups to chromenes. This process reduces the energy content of the resin systems and reduces the amount of shrinkage found during cure. Due to the presence of the solvent the process is safe and gives rise to low viscosity products suitable for resin transfer molding and filament winding type applications. Due to the high glass transition temperature, high modulus, and low moisture uptake the cured resins display better than 232 C/wet performance. The thermal stability of the ACT resins in air at 204 C is superior to that of conventional bismaleimide resins. The resins also display excellent electrical properties.

  4. Interpenetrating polymer networks from acetylene terminated materials

    NASA Technical Reports Server (NTRS)

    Connell, J. W.; Hergenrother, P. M.

    1989-01-01

    As part of a program to develop high temperature/high performance structural resins for aerospace applications, the chemistry and properties of a novel class of interpenetrating polymer networks (IPNs) were investigated. These IPNs consist of a simple diacetylenic compound (aspartimide) blended with an acetylene terminated arylene ether oligomer. Various compositional blends were prepared and thermally cured to evaluate the effect of crosslink density on resin properties. The cured IPNs exhibited glass transition temperatures ranging from 197 to 254 C depending upon the composition and cure temperature. The solvent resistance, fracture toughness and coefficient of thermal expansion of the cured blends were related to the crosslink density. Isothermal aging of neat resin moldings, adhesive and composite specimens showed a postcure effect which resulted in improved elevated temperature properties. The chemistry, physical and mechanical properties of these materials will be discussed.

  5. On the phase formation of titanium oxide thin films deposited by reactive DC magnetron sputtering: influence of oxygen partial pressure and nitrogen doping

    NASA Astrophysics Data System (ADS)

    Pandian, Ramanathaswamy; Natarajan, Gomathi; Rajagopalan, S.; Kamruddin, M.; Tyagi, A. K.

    2014-09-01

    This work describes about the control on phase formation in titanium oxide thin films deposited by reactive dc magnetron sputtering. Various phases of titanium oxide thin films were deposited by controlling the oxygen partial pressure during the sputtering process. By adding nitrogen gas to sputter gas mixture of oxygen and argon, the oxygen partial pressure was decreased further below the usual critical value, below and above which the sputtering yields metallic and oxide films, respectively. Furthermore, nitrogen addition eliminated the typical hysteretic behaviour between the flow rate and oxygen partial pressure, and significantly influenced the sputter rate. On increasing the oxygen partial pressure, the ratio between anatase and rutile fraction and grain size increases. The fracture cross-sectional scanning electron microscopy together with the complementary information from X-ray diffraction and micro-Raman investigations revealed the evolution and spatial distribution of the anatase and rutile phases. Both the energy delivered to the growing film and oxygen vacancy concentrations are correlated with the formation of various phases upon varying the oxygen partial pressure.

  6. Acetylene-argon plasmas measured at a biased substrate electrode for diamond-like carbon deposition: I. Mass spectrometry

    NASA Astrophysics Data System (ADS)

    Baby, A.; Mahony, C. M. O.; Maguire, P. D.

    2011-02-01

    We report, for the first time, quadrupole mass spectrometry of neutral and positive ionic hydrocarbon species measured at the rf-biased substrate electrode of an inductively coupled plasma for acetylene rich C2H2 : Ar mixtures under various bias, frequency and pressure conditions. It has been observed that, irrespective of initial gas mixture, the resultant plasma is dominated by argon neutrals and ions. This is attributed to highly efficient conversion of acetylene to C2H due to the enhanced electron density compared with a standard capacitive plasma where the acetylene (neutral and ion) species remain dominant. This conversion may be crucial to film formation via inert rather than hydrocarbon ion bombardment. In addition, the transient formation of CH4 from acetylene has been discovered using IR absorption spectroscopy with time constants similar to observed pressure variations. Rate coefficients and rates for many of the reaction mechanisms, calculated using measured electron energy distribution functions and species densities, are given. These results have important application in plasma models and growth studies for hydrogenated amorphous or diamond-like carbon film deposition. Film growth under similar plasma conditions is reported in an associated paper along with ion energy distributions for important growth species. .

  7. Anaerobic oxidation of acetylene by estuarine sediments and enrichment cultures

    USGS Publications Warehouse

    Culbertson, Charles W.; Zehnder, Alexander J. B.; Oremland, Ronald S.

    1981-01-01

    Acetylene disappeared from the gas phase of anaerobically incubated estuarine sediment slurries, and loss was accompanied by increased levels of carbon dioxide. Acetylene loss was inhibited by chloramphenicol, air, and autoclaving. Addition of 14C2H2 to slurries resulted in the formation of 14CO2 and the transient appearance of 14C-soluble intermediates, of which acetate was a major component. Acetylene oxidation stimulated sulfate reduction; however, sulfate reduction was not required for the loss of C2H2 to occur. Enrichment cultures were obtained which grew anaerobically at the expense of C2H2.

  8. Pyrethrum stabilization by inactivation of natural acetylenic impurities

    SciTech Connect

    Evans, A.J.

    1989-01-17

    This patent describes a mixture of naturally occurring pyrethroid substances and derivatives of naturally occurring polyacetylenic substances wherein the derivatives of polyacetylenic substances are formed by substantially inactivating the acetylenic functional groups to promote the stability of the pyrethroid substances.

  9. Hydrogenation of Acetylene-Ethylene Mixtures over Pd and Pd-Ag Alloys: First-Principles Based Kinetic Monte Carlo Simulations

    SciTech Connect

    Mei, Donghai; Neurock, Matthew; Smith, C Michael

    2009-10-22

    The kinetics for the selective hydrogenation of acetylene-ethylene mixtures over model Pd(111) and bimetallic Pd-Ag alloy surfaces were examined using first principles based kinetic Monte Carlo (KMC) simulations to elucidate the effects of alloying as well as process conditions (temperature and hydrogen partial pressure). The mechanisms that control the selective and unselective routes which included hydrogenation, dehydrogenation and C-C bond breaking pathways were analyzed using first-principle density functional theory (DFT) calculations. The results were used to construct an intrinsic kinetic database that was used in a variable time step kinetic Monte Carlo simulation to follow the kinetics and the molecular transformations in the selective hydrogenation of acetylene-ethylene feeds over Pd and Pd-Ag surfaces. The lateral interactions between coadsorbates that occur through-surface and through-space were estimated using DFT-parameterized bond order conservation and van der Waal interaction models respectively. The simulation results show that the rate of acetylene hydrogenation as well as the ethylene selectivity increase with temperature over both the Pd(111) and the Pd-Ag/Pd(111) alloy surfaces. The selective hydrogenation of acetylene to ethylene proceeds via the formation of a vinyl intermediate. The unselective formation of ethane is the result of the over-hydrogenation of ethylene as well as over-hydrogenation of vinyl to form ethylidene. Ethylidene further hydrogenates to form ethane and dehydrogenates to form ethylidyne. While ethylidyne is not reactive, it can block adsorption sites which limit the availability of hydrogen on the surface and thus act to enhance the selectivity. Alloying Ag into the Pd surface decreases the overall rated but increases the ethylene selectivity significantly by promoting the selective hydrogenation of vinyl to ethylene and concomitantly suppressing the unselective path involving the hydrogenation of vinyl to ethylidene

  10. Electronic Spectroscopy and Dynamics of the Acetylene - Complex

    NASA Astrophysics Data System (ADS)

    Ju, Shan-Shan

    The structures, intermolecular forces and excited state dynamics of acetylene(A) cdot Ar complex are investigated by combination of laser induced fluorescence spectroscopy pairwise potential model calculations. Acetylene is linear in the X state while trans-bent in the (A) state. Although only one structure has been known to exist for the acetylene(X) cdot Ar complex, two isomeric structures are determined for the acetylene(A) cdot Ar complex from the rotational band shape analysis of the fluorescence excitation spectra. One of the isomers has the argon sitting in the molecular plane of C _2H_2 (A), 3.77 A away from the center-of-mass of acetylene, the other has the argon 3.71 A above the plane on the C_2 axis. Formulas useful for calculating axis switching angles in non-planar molecules have been derived and applied to the two isomeric structures. It was found that despite the acetylene geometry change from the (X) to the (A) state, the axis switching effect is negligible for the complex spectral calculation. A pair potential model with parameters directly extracted from the ones calculated for ethene (X) cdot Ar is able to produce the two structures. Based on the structures and the calculated potential surface, three of the vdW frequencies are assigned to be: upsilon_{rm stretch } = 28 cm^{-1} for the out-of-plane isomer, upsilon_ {rm bend1} = 11 cm^ {-1} (the in-plane bend) and upsilon_{rm bend2} = 8.5 cm^{-1} (the out -of-plane bend) for the in-plane isomer. The existence of the two isomers allowed the study of the orientation dependence in intersystem crossing (ISC) of acetylene(S _1) induced by interaction with argon. Similar ISC lifetimes (~100 ns) were observed for the two isomers, suggesting that the pi and pi^* orbitals are equally susceptible to spin-changing interactions with Ar.

  11. The kinetics of dissolution of muscovites at 25°C and 1 atm CO 2 partial pressure

    NASA Astrophysics Data System (ADS)

    Lin, Feng-Chih; Clemency, Charles V.

    1981-04-01

    Two different dry-ground muscovites were placed separately in deionized water saturated with 1 atm partial pressure of carbon dioxide at room temperature and pressure for about 1000 hr. The carbonic acid formed buffered the bulk solution between 4.6 and 5.1 during the whole time of the experiment. K and Na were rapidly released by a reaction with hydrogen ions in the solution, which is usually attributed to a surface exchange reaction. The cation exchange capacity is close to the amount of K and Na released to the solution. However, measurement of surface areas of the micas both before and after the rapid release of K and Na, indicate that only one third of the cation exchange capacity can be attributed to release from the outer surfaces, whereas two thirds must be attributed to removal from within deeper parts of the structure. Approximately 2.5% of total K and Na from the interlayer regions, 1.5% of Mg from the octahedral sheets, and 0.5% of Si from the tetrahedral sheets were released by the end of the experiment, indicating that dissolution was incongruent in both cases. Si showed the slowest total release rate of all the ions. In the later stages (after 400 hr), the release rate of Si becomes a linear function of time. The linear release rate of Si was found to be 2.4 × 10 -17 mol/cm 2/sec for the ruby mica, and 2.7 × 10 -17 mol/cm 2/sec for the green mica. The rate-controlling mechanism in the dissolution of muscovite in the later stages is probably related to the rate of destruction of the tetrahedral sheets (Si-O bonds) which in turn is reflected by the rate of release of Si into the solution.

  12. Adsorption and reaction of acetylene on clean and oxygen-precovered Pd(100) studied with high-resolution X-ray photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Höfert, O.; Lorenz, M. P. A.; Streber, R.; Zhao, W.; Bayer, A.; Steinrück, H.-P.; Papp, C.

    2013-10-01

    We investigated the adsorption and thermal evolution of acetylene on clean Pd(100) and Pd(100) precovered with 0.25 ML oxygen. The measurements were performed in situ by fast XPS at the synchrotron radiation facility BESSY II. On Pd(100) acetylene molecularly adsorbs at 130 K. Upon heating transformation to a CCH species occurs around 390 K along with the formation of a completely dehydrogenated carbon species. On the oxygen-precovered surface partial CCH formation already occurs upon adsorption at 130 K, and the dehydrogenation temperature and the stability range of CCH are shifted to lower temperatures by ˜200 K.

  13. Adsorption and reaction of acetylene on clean and oxygen-precovered Pd(100) studied with high-resolution X-ray photoelectron spectroscopy.

    PubMed

    Höfert, O; Lorenz, M P A; Streber, R; Zhao, W; Bayer, A; Steinrück, H-P; Papp, C

    2013-10-28

    We investigated the adsorption and thermal evolution of acetylene on clean Pd(100) and Pd(100) precovered with 0.25 ML oxygen. The measurements were performed in situ by fast XPS at the synchrotron radiation facility BESSY II. On Pd(100) acetylene molecularly adsorbs at 130 K. Upon heating transformation to a CCH species occurs around 390 K along with the formation of a completely dehydrogenated carbon species. On the oxygen-precovered surface partial CCH formation already occurs upon adsorption at 130 K, and the dehydrogenation temperature and the stability range of CCH are shifted to lower temperatures by ∼200 K. PMID:24182063

  14. Nonstationary coherent optical effects caused by pulse propagation through acetylene-filled hollow-core photonic-crystal fibers

    NASA Astrophysics Data System (ADS)

    Ocegueda, M.; Hernandez, E.; Stepanov, S.; Agruzov, P.; Shamray, A.

    2014-06-01

    Experimental observations of nonstationary coherent optical phenomena, i.e., optical nutation, free induction, and photon echo, in the acetylene (12C2H2) filled hollow-core photonic-crystal fiber (PCF) are reported. The presented results were obtained for the acetylene vibration-rotational transition P9 at wavelength 1530.37 nm at room temperature under a gas pressure of <0.5 Torr. An all-fiber pumped-through cell based on the commercial 2.6-m-long PCF with a 10-μm hollow-core diameter was used. The characteristic relaxation time T2 during which the optical coherent effects were typically observed in our experiments was estimated to be ≈8 ns. This time is governed by the limited time of the acetylene molecules' presence inside the effective PCF modal area and by intermolecule collisions. An accelerated attenuation of the optical nutation oscillations is explained by a random orientation of acetylene molecules.

  15. Reproducible group-V partial pressure rapid thermal annealing of InP and GaAs

    NASA Astrophysics Data System (ADS)

    Pearton, S. J.; Katz, A.; Geva, M.

    1990-09-01

    We compare the effectiveness of two types of SiC-coated graphite susceptors in providing degradation-free rapid thermal annealing of InP and GaAs. The first type of susceptor must be charged with the group-V species prior to any annealing cycles. Under the optimum charging conditions, effective surface protection is provided for up to five sequential high-temperature (900 °C, 10 s) anneals of GaAs, or only one anneal (750 °C, 10 s) of InP before recharging is necessary. The incorporation of small reservoirs into the susceptor allows for the provision of a constant group-V partial pressure over the wafer, and it appears that for this type of susceptor many dozens of InP or GaAs wafers can be annealed without any apparent surface degradation. The relative merits of using InAs, GaAs, or InP as the group-V source in the reservoirs have been compared, and it is found that the best protection is achieved when one uses the same semiconductor in the reservoirs as is being annealed.

  16. Laser heating and oxygen partial pressure effects on the dynamic magnetic properties of perpendicular CoFeAlO films

    NASA Astrophysics Data System (ADS)

    Wu, Di; Li, Wei; Tang, Minghong; Zhang, Zongzhi; Lou, Shitao; Jin, Q. Y.

    2016-07-01

    The impact of oxidation and laser heating on the dynamic magnetic properties of perpendicularly magnetized Co50Fe25Al25O films has been studied by time-resolved magneto-optical Kerr effect in a fs-laser pump-probe setup. We find that pump laser fluence Fp can affect the effective magnetic anisotropy field and thus the precession frequency f seriously, leading to an increased dependence of effective magnetic damping factor αeff on the external field at higher fluences. Moreover, the αeff increases with increasing the oxygen partial pressure PO2 while the uniaxial anisotropy energy Ku and Landau factor g decrease, owing to the increased proportion of superparamagnetic CoFe oxides formed by over-oxidation. By optimizing both the Fp and PO2, the intrinsic damping factor is determined to be lower than 0.028 for the perpendicular film showing a uniaxial anisotropy energy as high as 4.3×106 erg/cm3. The results in this study provide a promising approach to manipulate the magnetic parameters for possible applications in spintronic devices.

  17. Partial hydrophilic modification of biaxially oriented polypropylene film by an atmospheric pressure plasma jet with the allylamine monomer

    NASA Astrophysics Data System (ADS)

    Chen, W. X.; Yu, J. S.; Hu, W.; Chen, G. L.

    2016-11-01

    In this paper, the partial modification of the biaxially oriented polypropylene (BOPP) film for potential biological and packaging applications was achieved via hydrophilic modification using atmospheric pressure plasma jet (APPJ). In the APPJ system, the allylamine (ALA) monomer was polymerized on the BOPP surface by either the Ar/O2 or the He/O2 plasma. The results showed that plasmatic modification created many micro/nano sized holes on the BOPP film, which increased the surface roughness dramatically and the increased roughness enhanced the combining intensity between the BOPP film and the ALA polymer. However, such a plasmatic modification increased the water vapor permeability. The FTIR and XPS characterizations showed that the amine groups were grafted onto the BOPP film, and the contact angle of the BOPP film decreases from 98.5° to 8°. Compared with the BOPP films treated by the Ar or He plasma, the barrier property of the modified BOPP film increased significantly when the ALA polymer was incorporated. The bio-affinity/toxicity of ALA polymer was illustrated by the attachment of the cultured SMMC-7721 hepatoma cells on the modified BOPP film. The significant enhancement in the cell density indicated that modified BOPP film was highly bio-compatible and non-toxic, especially treated with the Ar/O2/ALA plasma.

  18. The jumbo squid, Dosidicus gigas (Ommastrephidae), living in oxygen minimum zones I: Oxygen consumption rates and critical oxygen partial pressures

    NASA Astrophysics Data System (ADS)

    Trueblood, Lloyd A.; Seibel, Brad A.

    2013-10-01

    Dosidicus gigas is a large, metabolically active, epipelagic squid known to undertake diel vertical migrations across a large temperature and oxygen gradient in the Eastern Pacific. Hypoxia is known to cause metabolic suppression in D. gigas. However, the precise oxygen level at which metabolic suppression sets in is unknown. Here we describe a novel ship-board swim tunnel respirometer that was used to measure metabolic rates and critical oxygen partial pressures (Pcrit) for adult squids (2-7kg). Metabolic rate measurements were validated by comparison to the activity of the Krebs cycle enzyme, citrate synthase, in mantle muscle tissue (2-17kg). We recorded a mean routine metabolic rate of 5.91μmolg-1h-1 at 10°C and 12.62μmolg-1h-1 at 20°C. A temperature coefficient, Q10, of 2.1 was calculated. D. gigas had Pcrits of 1.6 and 3.8kPa at 10 and 20°C, respectively. Oxygen consumption rate (MO2) varied with body mass (M) according to MO2=11.57M-0.12±0.03 at 10°C. Citrate synthase activity varied with body mass according to Y=9.32M-0.19±0.02.

  19. Two-photon high-resolution measurement of partial pressure of oxygen in cerebral vasculature and tissue.

    PubMed

    Sakadzić, Sava; Roussakis, Emmanuel; Yaseen, Mohammad A; Mandeville, Emiri T; Srinivasan, Vivek J; Arai, Ken; Ruvinskaya, Svetlana; Devor, Anna; Lo, Eng H; Vinogradov, Sergei A; Boas, David A

    2010-09-01

    Measurements of oxygen partial pressure (pO(2)) with high temporal and spatial resolution in three dimensions is crucial for understanding oxygen delivery and consumption in normal and diseased brain. Among existing pO(2) measurement methods, phosphorescence quenching is optimally suited for the task. However, previous attempts to couple phosphorescence with two-photon laser scanning microscopy have faced substantial difficulties because of extremely low two-photon absorption cross-sections of conventional phosphorescent probes. Here we report to our knowledge the first practical in vivo two-photon high-resolution pO(2) measurements in small rodents' cortical microvasculature and tissue, made possible by combining an optimized imaging system with a two-photon-enhanced phosphorescent nanoprobe. The method features a measurement depth of up to 250 microm, sub-second temporal resolution and requires low probe concentration. The properties of the probe allowed for direct high-resolution measurement of cortical extravascular (tissue) pO(2), opening many possibilities for functional metabolic brain studies. PMID:20693997

  20. Two-photon high-resolution measurement of partial pressure of oxygen in cerebral vasculature and tissue

    PubMed Central

    Sakadžić, Sava; Roussakis, Emmanuel; Yaseen, Mohammad A.; Mandeville, Emiri T.; Srinivasan, Vivek J.; Arai, Ken; Ruvinskaya, Svetlana; Devor, Anna; Lo, Eng H.; Vinogradov, Sergei A.; Boas, David A.

    2010-01-01

    The ability to measure oxygen partial pressure (pO2) with high temporal and spatial resolution in three dimensions is crucial for understanding oxygen delivery and consumption in normal and diseased brain. Among existing pO2 measurement methods, phosphorescence quenching is optimally suited for the task. However, previous attempts to couple phosphorescence with two-photon laser scanning microscopy have faced substantial difficulties because of extremely low two-photon absorption cross-sections of conventional phosphorescent probes. Here, we report the first practical in vivo two-photon high-resolution pO2 measurements in small rodents’ cortical microvasculature and tissue, made possible by combining an optimized imaging system with a two-photon-enhanced phosphorescent nanoprobe. The method features a measurement depth of up to 250 µm, sub-second temporal resolution and requires low probe concentration. Most importantly, the properties of the probe allowed for the first direct high-resolution measurement of cortical extravascular (tissue) pO2, opening numerous possibilities for functional metabolic brain studies. PMID:20693997

  1. Temporal resilience and dynamics of anaerobic methane-oxidizing microbial communities to short-term changes in methane partial pressures

    NASA Astrophysics Data System (ADS)

    Klasek, S.; Tiantian, Y.; Torres, M. E.; Colwell, F. S.; Wang, F.; Liang, L.

    2015-12-01

    Marine sediments produce tens to hundreds of teragrams of methane annually, which is released from the seabed at thousands of cold seeps distributed globally along continental margins. Around 80-90% of this methane is consumed in shallower sediment layers before reaching the hydrosphere, in a microbially-mediated process known as anaerobic oxidation of methane (AOM) However, cold seeps appear to exhibit temporal variation in gas flux intensity, and AOM filter efficiency at cold seeps generally decreases with fluid flow rate. To our knowledge, the degree to which temporal heterogeneity in subsurface methane flux stimulates AOM community growth and adaptation to increased methane concentrations has not been investigated. Static high-pressure bioreactors were used to incubate sulfate-methane transition zone (SMTZ) and methanogenic zone sediments underlying a Mediterranean mud volcano gas flare under in situ temperature and pressure at 8 MPa methane. Sulfide production rates of 0.4 μmol/cm3/day in both sediment regimes after 4 months of incubation suggested the resilience of the marine subsurface methane filter may extend well below the SMTZ (40 cm). Similar incubations of SMTZ samples from below a gas flare off Svalbard at saturating (3.8 MPa) and 0.2 MPa methane are being sampled after 1 week, 4 weeks, and 4 months; sulfide production rates of 8-18 nmol/cm3/day were first observed after 4 weeks of incubation. Sediment samples at all specified time points for both sets of incubations were collected for nucleic acid extraction and cell fixation. Anaerobic methanotrophic archaea (ANME) and sulfate-reducing bacteria (SRB) are expected dominant taxa in enriched and non-enriched communities. 16S rDNA community analysis is expected to reveal additional microbial players involved in the short-term adaptation to higher methane partial pressures in the marine subsurface. Increased AOM community activity (RNA/DNA ratio) and copy numbers of methane cycling transcripts (mcr

  2. Mortality of workers at acetylene production plants.

    PubMed Central

    Newhouse, M L; Matthews, G; Sheikh, K; Knight, K L; Oakes, D; Sullivan, K R

    1988-01-01

    To reduce the risk of explosion oxyacetylene cylinders are filled with a spongy mass, acetone is added to saturate the mass, and acetylene is pumped into the cylinder. The first cylinders manufactured before 1936 used a kapok filling topped off with about 16 oz of crocidolite asbestos, with a metal gauze thimble inserted to reduce risk of flash back. Cylinders must be examined annually. The use of crocidolite ceased in 1972 and other fillings have been adopted since 1970; kapok cylinders now constitute less than 5% of the total stock. To assess possible hazards, a mortality study of workers first employed between 1935 and 1975 and followed up to December 1984 was undertaken. Simulation tests showed low concentrations of asbestos in the air even in the earliest period. The population studied consisted of 370 workers at the Bilston plant in the West Midlands, 611 at the 14 other plants in England and Wales, and 120 in Scotland. No deaths occurred from mesothelial tumours but there was an excess of deaths from cancer, particularly lung cancer, cancer of the stomach, and cancer of the pancreas, the latter accounting for eight deaths. Risks appeared to be concentrated at the Bilston plant. The importance of these findings is discussed. PMID:3342189

  3. Electron impact induced anion production in acetylene.

    PubMed

    Szymańska, Ewelina; Čadež, Iztok; Krishnakumar, E; Mason, Nigel J

    2014-02-28

    A detailed experimental investigation of electron induced anion production in acetylene, C2H2, in the energy range between 1 and 90 eV is presented. The anions are formed by two processes in this energy range: dissociative electron attachment (DEA) and dipolar dissociation (DD). DEA in C2H2 is found to lead to the formation of H(-) and C2(-)/C2H(-) through excitation of resonances in the electron energy range 1-15 eV. These anionic fragments are formed with super thermal kinetic energy and reveal no anisotropy in the angular distributions. DD in C2H2 leads to the formation of H(-), C(-)/CH(-) and C2(-)/C2H(-) with threshold energies of 15.7, 20.0 and 16.5 eV respectively. The measured anion yields have been used to calculate anion production rates for H(-), C(-)/CH(-) and C2(-)/C2H(-) in Titan's ionosphere. PMID:24343432

  4. Ion-induced dissociation dynamics of acetylene

    SciTech Connect

    De, Sankar; Rajput, Jyoti; Roy, A.; Safvan, C. P.; Ghosh, P. N.

    2008-02-15

    We report on the results of dissociation dynamics of multiple charged acetylene molecules formed in collision with 1.2 MeV Ar{sup 8+} projectiles. Using the coincidence map, we can separate out the different dissociation pathways between carbon and hydrogen ionic fragments as well as complete two-body breakup events. From the measured slopes of the coincidence islands for carbon atomic fragments and theoretical values determined from the charge and momentum distribution of the correlated particles, we observe a diatom like behavior of the C-C charged complex during dissociation of multiply charged C{sub 2}H{sub 2}. We conclude that this behavior in breakup dynamics is a signature of sequentiality in dissociation of this multiply charged molecular species. The shape and orientation of the islands give further information about the momentum balance in the fragmentation process of two- or many-body dissociation pathways. Kinetic energy release of different breakup channels are reported here and compared with values calculated from the pure Coulomb explosion model.

  5. Process hydrogenates unwanted diolefins and acetylenes

    SciTech Connect

    Vora, B.V. )

    1988-12-05

    Diolefins and actetylenes in C/sub 3//C/sub 4/ olefin streams can be selectively hydrogenated to produce high-purity mono-olefins for downstream polyolefin production. C/sub 3//C/sub 4/ olefin sources, fluid catalytic cracking (FCC), steam crackers, and dehydrogenation of C/sub 3//C/sub 4/ paraffins, all contain these undesirable polyunsaturated compounds. Hydrogenation of these compounds in alkylation unit feeds can also improve the economics of the alkylation process. Production of high-purity mono-olefins for downstream polyolefins production requires a feedstock that is essentially free of dienes and acetylenes to minimize undesirable side reactions. Although alkylation units can tolerate some diolefins in the feed, economics dictate that these diolefins should be minimized. The selective hydrogenation process (SHP) developed by others at its Marl, West Germany, plant, has undergone additional development work since commercialization of the process in 1980. The unit was designed to feed 160,000 metric tons/year of clean C/sub 4/ raffinate from a steam cracker, with a maximum polyunsaturated content of 0.8 wt%.

  6. Acetylene on Titan’s Surface

    NASA Astrophysics Data System (ADS)

    Singh, S.; McCord, T. B.; Combe, J.-Ph.; Rodriguez, S.; Cornet, T.; Le Mouélic, S.; Clark, R. N.; Maltagliati, L.; Chevrier, V. F.

    2016-09-01

    Titan’s atmosphere is opaque in the near-infrared due to gaseous absorptions, mainly by methane, and scattering by aerosols, except in a few “transparency windows.” Thus, the composition of Titan’s surface remains difficult to access from space and is still poorly constrained. Photochemical models suggest that most of the organic compounds formed in the atmosphere are heavy enough to condense and build up at the surface in liquid and solid states over geological timescales. Acetylene (C2H2) net production in the atmosphere is predicted to be larger than any other compound and C2H2 has been speculated to exist on the surface of Titan. C2H2 was detected as a trace gas sublimated/evaporated from the surface using the Gas Chromatograph Mass Spectrometer after the landing of the Huygens probe. Here we show evidence of C2H2 on the surface of Titan by detecting absorption bands at 1.55 and 4.93 μm using the Cassini Visual and Infrared Mapping Spectrometer at three different equatorial areas—Tui Regio, eastern Shangri La, and Fensal–Aztlan/Quivira. We found that C2H2 is preferentially detected in low-albedo areas, such as sand dunes and near the Huygens landing site. The specific location of the C2H2 detections suggests that C2H2 is mobilized by surface processes, such as surface weathering by liquids through dissolution/evaporation processes.

  7. Effects of Temperature, Oxygen Partial Pressure, and Materials Selection on Slag Infiltration into Porous Refractories for Entrained-Flow Gasifiers

    NASA Astrophysics Data System (ADS)

    Kaneko, Tetsuya Kenneth

    The penetration rate of molten mineral contents (slag) from spent carbonaceous feedstock into porous ceramic-oxide refractory linings is a critical parameter in determining the lifecycle of integrated gasification combined cycle energy production plants. Refractory linings that withstand longer operation without interruption are desirable because they can mitigate consumable and maintenance costs. Although refractory degradation has been extensively studied for many other high-temperature industrial processes, this work focuses on the mechanisms that are unique to entrained-flow gasification systems. The use of unique feedstock mixtures, temperatures from 1450 °C to 1600 °C, and oxygen partial pressures from 10-7 atm to 10-9 atm pose engineering challenges in designing an optimal refractory material. Experimentation, characterization, and modeling show that gasifier slag infiltration into porous refractory is determined by interactions between the slag and the refractory that either form a physical barrier that impedes fluid flow or induce an increased fluid viscosity that decelerates the velocity of the fluid body. The viscosity of the slag is modified by the thermal profile of the refractory along the penetration direction as well as reactions between the slag and refractory that alter the chemistry, and thereby the thermo-physical properties of the fluid. Infiltration experiments reveal that the temperature gradient inherently present along the refractory lining limits penetration. A refractory in near-isothermal conditions demonstrates deeper slag penetration as compared to one that experiences a steeper thermal profile. The decrease in the local temperatures of the slag as it travels deeper into the refractory increases the viscosity of the fluid, which in turn slows the infiltration velocity of fluid body into the pores of the refractory microstructure. With feedstock mixtures that exhibit high iron-oxide concentrations, a transition-metal-oxide, the oxygen

  8. Influence of the N2 partial pressure on the characteristics of CrZrN coatings synthesized Using a segment CrZr target.

    PubMed

    Kim, YoungSu; Kim, GwangSeok; Lee, SangYul

    2011-10-01

    In this study, CrZrN films were synthesized by unbalanced magnetron sputtering (UBM) under various N2 partial pressures and their characteristics such as crystalline structure, surface morphology, microstructure and mechanical properties as a function of the N2 partial pressures were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), nanoindentation, wear tests, and corrosion tests. Results revealed that, with increasing the N2 partial pressure from 0.05 to 0.21 Pa, the nitrogen content of the films increased from approximately 40.9 to 53.7 at%, the deposition rate decreased from approximately 100 to 59 nm/min and the surface roughness (Rms value) was increased from approximately 0.57 to 1.79 nm. The Cr37.3-Zr9.0-N53.7 film has the highest hardness, elastic modulus, and plastic deformation resistance of 36 GPa, 380 GPa, and 0.41, respectively. The Cr37.3-Zr9.0-N53.7 film also has the lowest friction coefficient and wear rate of 0.19 and 3.01 (10(-6)m3/Nm) at room temperature. In addition, the potentiodynamic test results showed the corrosion resistance of the CrZrN films became increased significantly and their corrosion current density (i(corr)), corrosion potentials (Ecorr) and corrosion rate decreased with increasing N2 partial pressure. PMID:22400261

  9. Oxygen Partial Pressure Is a Rate-Limiting Parameter for Cell Proliferation in 3D Spheroids Grown in Physioxic Culture Condition

    PubMed Central

    Gomes, Aurélie; Guillaume, Ludivine; Grimes, David Robert; Fehrenbach, Jérôme; Lobjois, Valérie; Ducommun, Bernard

    2016-01-01

    The in situ oxygen partial pressure in normal and tumor tissues is in the range of a few percent. Therefore, when studying cell growth in 3D culture systems, it is essential to consider how the physiological oxygen concentration, rather than the one in the ambient air, influences the proliferation parameters. Here, we investigated the effect of reducing oxygen partial pressure from 21% to 5% on cell proliferation rate and regionalization in a 3D tumor spheroid model. We found that 5% oxygen concentration strongly inhibited spheroid growth, changed the proliferation gradient and reduced the 50% In Depth Proliferation index (IDP50), compared with culture at 21% oxygen. We then modeled the oxygen partial pressure profiles using the experimental data generated by culturing spheroids in physioxic and normoxic conditions. Although hypoxia occurred at similar depth in spheroids grown in the two conditions, oxygen partial pressure was a major rate-limiting factor with a critical effect on cell proliferation rate and regionalization only in spheroids grown in physioxic condition and not in spheroids grown at atmospheric normoxia. Our findings strengthen the need to consider conducting experiment in physioxic conditions (i.e., tissue normoxia) for proper understanding of cancer cell biology and the evaluation of anticancer drugs in 3D culture systems. PMID:27575790

  10. Oxygen Partial Pressure Is a Rate-Limiting Parameter for Cell Proliferation in 3D Spheroids Grown in Physioxic Culture Condition.

    PubMed

    Gomes, Aurélie; Guillaume, Ludivine; Grimes, David Robert; Fehrenbach, Jérôme; Lobjois, Valérie; Ducommun, Bernard

    2016-01-01

    The in situ oxygen partial pressure in normal and tumor tissues is in the range of a few percent. Therefore, when studying cell growth in 3D culture systems, it is essential to consider how the physiological oxygen concentration, rather than the one in the ambient air, influences the proliferation parameters. Here, we investigated the effect of reducing oxygen partial pressure from 21% to 5% on cell proliferation rate and regionalization in a 3D tumor spheroid model. We found that 5% oxygen concentration strongly inhibited spheroid growth, changed the proliferation gradient and reduced the 50% In Depth Proliferation index (IDP50), compared with culture at 21% oxygen. We then modeled the oxygen partial pressure profiles using the experimental data generated by culturing spheroids in physioxic and normoxic conditions. Although hypoxia occurred at similar depth in spheroids grown in the two conditions, oxygen partial pressure was a major rate-limiting factor with a critical effect on cell proliferation rate and regionalization only in spheroids grown in physioxic condition and not in spheroids grown at atmospheric normoxia. Our findings strengthen the need to consider conducting experiment in physioxic conditions (i.e., tissue normoxia) for proper understanding of cancer cell biology and the evaluation of anticancer drugs in 3D culture systems. PMID:27575790

  11. Effects of ambient and acute partial pressures of ozone on leaf net CO sub 2 assimilation of field-grown Vitis vinifera L

    SciTech Connect

    Roper, T.R.; Williams, L.E. Kearney Agricultural Center, Parlier, CA )

    1989-12-01

    Mature, field-grown Vitis vinifera L. grapevines grown in open-top chambers were exposed to either charcoal-filtered air or ambient ozone partial pressures throughout the growing season. Individual leaves also were exposed to ozone partial pressures of 0.2, 0.4, or 0.6 micropascals per pascal for 5 hours. No visual ozone damage was found on leaves exposed to any of the treatments. Chronic exposure to ambient O{sub 3} partial pressures reduced net CO{sub 2} assimilation rate (A) between 5 and 13% at various times throughout the season when compared to the filtered treatment. Exposure of leaves to 0.2 micropascals per pascal O{sub 3} for 5 hours had no significant effect on A; however, A was reduced 84% for leaves exposed to 0.6 micropascals per pascal O{sub 3} when compared to the controls after 5 hours. Intercellular CO{sub 2} partial pressure (c{sub i}) was lower for leaves exposed to 0.2 micropascals per pascal O{sub 3} when compared to the controls, while c{sub i} of the leaves treated with 0.6 micropascals per pascal of O{sub 3} increased during the fumigation. The long-term effects of ambient O{sub 3} and short-term exposure to acute levels of O{sub 3} reduced grape leaf photosynthesis due to a reduction in both stomatal and mesophyll conductances.

  12. Effects of Ambient and Acute Partial Pressures of Ozone on Leaf Net CO2 Assimilation of Field-Grown Vitis vinifera L. 1

    PubMed Central

    Roper, Teryl R.; Williams, Larry E.

    1989-01-01

    Mature, field-grown Vitis vinifera L. grapevines grown in open-top chambers were exposed to either charcoal-filtered air or ambient ozone partial pressures throughout the growing season. Individual leaves also were exposed to ozone partial pressures of 0.2, 0.4, or 0.6 micropascals per pascal for 5 hours. No visual ozone damage was found on leaves exposed to any of the treatments. Chronic exposure to ambient O3 partial pressures reduced net CO2 assimilation rate (A) between 5 and 13% at various times throughout the season when compared to the filtered treatment. Exposure of leaves to 0.2 micropascals per pascal O3 for 5 hours had no significant effect on A; however, A was reduced 84% for leaves exposed to 0.6 micropascals per pascal O3 when compared to the controls after 5 hours. Intercellular CO2 partial pressure (ci) was lower for leaves exposed to 0.2 micropascals per pascal O3 when compared to the controls, while ci of the leaves treated with 0.6 micropascals per pascal of 03 increased during the fumigation. The long-term effects of ambient O3 and short-term exposure to acute levels of O3 reduced grape leaf photosynthesis due to a reduction in both stomatal and mesophyll conductances. PMID:16667208

  13. Reproducing early Martian atmospheric carbon dioxide partial pressure by modeling the formation of Mg-Fe-Ca carbonate identified in the Comanche rock outcrops on Mars

    NASA Astrophysics Data System (ADS)

    Berk, Wolfgang; Fu, Yunjiao; Ilger, Jan-Michael

    2012-10-01

    The well defined composition of the Comanche rock's carbonate (Magnesite0.62Siderite0.25Calcite0.11Rhodochrosite0.02) and its host rock's composition, dominated by Mg-rich olivine, enable us to reproduce the atmospheric CO2partial pressure that may have triggered the formation of these carbonates. Hydrogeochemical one-dimensional transport modeling reveals that similar aqueous rock alteration conditions (including CO2partial pressure) may have led to the formation of Mg-Fe-Ca carbonate identified in the Comanche rock outcrops (Gusev Crater) and also in the ultramafic rocks exposed in the Nili Fossae region. Hydrogeochemical conditions enabling the formation of Mg-rich solid solution carbonate result from equilibrium species distributions involving (1) ultramafic rocks (ca. 32 wt% olivine; Fo0.72Fa0.28), (2) pure water, and (3) CO2partial pressures of ca. 0.5 to 2.0 bar at water-to-rock ratios of ca. 500 molH2O mol-1rock and ca. 5°C (278 K). Our modeled carbonate composition (Magnesite0.64Siderite0.28Calcite0.08) matches the measured composition of carbonates preserved in the Comanche rocks. Considerably different carbonate compositions are achieved at (1) higher temperature (85°C), (2) water-to-rock ratios considerably higher and lower than 500 mol mol-1 and (3) CO2partial pressures differing from 1.0 bar in the model set up. The Comanche rocks, hosting the carbonate, may have been subjected to long-lasting (>104 to 105 years) aqueous alteration processes triggered by atmospheric CO2partial pressures of ca. 1.0 bar at low temperature. Their outcrop may represent a fragment of the upper layers of an altered olivine-rich rock column, which is characterized by newly formed Mg-Fe-Ca solid solution carbonate, and phyllosilicate-rich alteration assemblages within deeper (unexposed) units.

  14. The effect of oxygen partial pressure on protein synthesis and collagen hydroxylation by mature periodontal tissues maintained in organ cultures

    PubMed Central

    Yen, Edwin H. K.; Sodek, Jaro; Melcher, Antony H.

    1979-01-01

    Mature periodontal tissues from adult-mouse first mandibular molars were cultured in a continuous-flow organ-culture system which allowed the regulation of both ascorbic acid concentration and pO2 (oxygen partial pressure). Protein synthesis was measured by analysing the incorporation of [3H]proline into collagenous and non-collagenous proteins during the last 24h of a 2-day culture. At low pO2 [16.0kPa (approx. 120mmHg)] approx. 60% of protein-incorporated [3H]proline was found in collagenous proteins. However, it was evident that this collagen was considerably underhydroxylated. At high pO2 [56.0kPa (approx. 420mmHg)], both the amount of collagen deposited in the tissues and the degree of hydroxylation were increased considerably. In contrast, no significant effect on non-collagenous protein was observed. Tissues cultured at low pO2 for the first 48h were unable to respond to a subsequent increase in pO2 during the last 24h. Analysis of pepsin-solubilized collagen α-chains labelled with [14C]glycine demonstrated the synthesis of both type-I and type-III collagens by explants cultured for 48h at high pO2. Type-III collagen comprised 20–30% of the radioactivity in α-chains in both the periodontal ligament and the tissues of the alveolar process. The pattern of protein synthesis in the alveolar tissues at high pO2 was similar to that observed in these tissues in vivo. However, in the cultured periodontal ligament the proportions of non-collagenous proteins and type-III collagens were increased in comparison with the tissue in vivo. PMID:454369

  15. Residual oxygen time model for oxygen partial pressure near 130 kPa (1.3 atm).

    PubMed

    Shykoff, Barbara E

    2015-01-01

    A two-part residual oxygen time model predicts the probability of detectible pulmonary oxygen toxicity P(P[O2tox]) after dives with oxygen partial pressure (PO2) approximately 130 kPa, and provides a tool to plan dive series with selected risk of P[O2tox]. Data suggest that pulmonary oxygen injury at this PO2 is additive between dives. Recovery begins after a delay and continues during any following dive. A logistic relation expresses P(P[O2tox]) as a function of dive duration (T(dur)) [hours]: P(P[O2tox]) = 100/[1+exp (3.586-0.49 x T(dur))] This expression maps T(dur) to P(P[O2tox]) or, in the linear mid-portion of the curve, P(P[O2tox]) usefully to T(dur). For multiple dives or during recovery, it maps to an equivalent dive duration, T(eq). T(eq) was found after second dives of duration T(dur 2). Residual time from the first dive t(r) = T(eq) - T(dur2). With known t(r), t and T(dur) a recovery model was fitted. t(r) = T(dur) x exp [-k x((t-5)/T(dur)2], where t = t - 5 hours, k = 0.149 for resting, and 0.047 for exercising divers, and t represents time after surfacing. The fits were assessed for 1,352 man-dives. Standard deviations of the residuals were 8.5% and 18.3% probability for resting or exercise dives, respectively. PMID:26742255

  16. Carbon dioxide partial pressure and 13C content of north temperate and boreal lakes at spring ice melt

    USGS Publications Warehouse

    Striegl, R.G.; Kortelainen, Pirkko; Chanton, J.P.; Wickland, K.P.; Bugna, G.C.; Rantakari, M.

    2001-01-01

    Carbon dioxide (CO2) accumulates under lake ice in winter and degasses to the atmosphere after ice melt. This large springtime CO2 pulse is not typically considered in surface-atmosphere flux estimates, because most field studies have not sampled through ice during late winter. Measured CO2 partial pressure (pCO2) of lake surface water ranged from 8.6 to 4,290 Pa (85-4,230 ??atm) in 234 north temperate and boreal lakes prior to ice melt during 1998 and 1999. Only four lakes had surface pCO2 less than or equal to atmospheric pCO2, whereas 75% had pCO2 >5 times atmospheric. The ??13CDIC (DIC = ??CO2) of 142 of the lakes ranged from -26.28??? to +0.95.???. Lakes with the greatest pCO2 also had the lightest ??13CDIC, which indicates respiration as their primary CO2 source. Finnish lakes that received large amounts of dissolved organic carbon from surrounding peatlands had the greatest pCO2. Lakes set in noncarbonate till and bedrock in Minnesota and Wisconsin had the smallest pCO2 and the heaviest ??13CDIC, which indicates atmospheric and/or mineral sources of C for those lakes. Potential emissions for the period after ice melt were 2.36 ?? 1.44 mol CO2 m-2 for lakes with average pCO2 values and were as large as 13.7 ?? 8.4 mol CO2 m-2 for lakes with high pCO2 values.

  17. Microstructure, mechanical and optical properties of TiAlON coatings sputter-deposited with varying oxygen partial pressures

    NASA Astrophysics Data System (ADS)

    Schalk, Nina; Thierry Simonet Fotso, J. F.; Holec, David; Fian, Alexander; Jakopic, Georg; Terziyska, Velislava L.; Daniel, Rostislav; Mitterer, Christian

    2016-01-01

    Due to their excellent mechanical and optical properties as well as chemical stability, the synthesis of transition metal oxynitride thin films has attracted growing interest in the last years. Within this work, the evolution of the structure and properties of TiAlON coatings over a wide compositional range, from the nitride to the oxide side, was investigated. The coatings were grown on Si substrates in a laboratory-scale unbalanced magnetron dc sputtering system from powder metallurgical TiAl targets with an Al/Ti atomic ratio of 60/40, using a constant level of nitrogen with rising oxygen partial pressure. Coating composition and microstructure were investigated by energy- and wavelength-dispersive x-ray spectroscopy, x-ray diffraction, x-ray photoelectron spectroscopy, Raman spectroscopy and transmission electron microscopy. Furthermore, the mechanical and optical properties were evaluated using nanoindentation and spectroscopic ellipsometry, respectively. Oxygen concentrations of up to 49 at.% within the films could be obtained, at the expense of the nitrogen content. The oxygen-free coating exhibited a single-phase fcc-Ti1-x Al x N structure. With increasing oxygen content the structure remained fcc-Ti1-x Al x N based, but additional fractions of amorphous oxides were formed. The structural evolution was corroborated by ab initio calculations. Decreasing coating hardness could be observed with increasing oxygen concentration. The refraction index and extinction coefficient were lower for coatings with higher oxygen content, but the behavior of the optical properties remained Ti1-x Al x N-like over the investigated spectral range.

  18. Identification of Acetylene on Titan's Surface

    NASA Astrophysics Data System (ADS)

    Singh, S.; McCord, T. B.; Rodriguez, S.; Combe, J. P.; Cornet, T.; Le Mouelic, S.; Maltagliati, L.; Chevrier, V.; Clark, R. N.

    2015-12-01

    Titan's atmosphere is opaque in the near infrared due to gaseous absorptions, mainly by methane, and scattering by aerosols, except in a few "transparency windows" (e.g., Sotin et al., 2005). Thus, the composition of Titan surface remains difficult to access from space and is still poorly constrained, limited to ethane in the polar lakes (Brown et al., 2008) and a few possible organic molecules on the surface (Clark et al., 2010). Photochemical models suggest that most of the organic compounds formed in the atmosphere are heavy enough to condense and build up at the surface in liquid and solid states over geological timescale (Cordier et al., 2009, 2011). Acetylene (C2H2) is one of the most abundant organic molecules in the atmosphere and thus thought to present on the surface as well. Here we report direct evidence of solid C2H2 on Titan's surface using Cassini Visual and Infrared Mapping Spectrometer (VIMS) data. By comparing VIMS observations and laboratory measurements of solid and liquid C2H2, we identify a specific absorption at 1.55 µm that is widespread over Titan but is particularly strong in the brightest terrains. This surface variability suggests that C2H2 is mobilized by surface processes, such as surface weathering, topography, and dissolution/evaporation. The detection of C2H2 on the surface of Titan opens new paths to understand and constrain Titan's surface activity. Since C2H2 is highly soluble in Titan liquids (Singh et al. 2015), it can easily dissolve in methane/ethane and may play an important role in carving of fluvial channels and existence of karstic lakes at higher latitudes on Titan. These processes imply the existence of a dynamic surface with a continued history of erosion and deposition of C2H2 on Titan.

  19. Measurements of seismic attenuation and transient fluid pressure in partially saturated Berea sandstone: evidence of fluid flow on the mesoscopic scale

    NASA Astrophysics Data System (ADS)

    Tisato, Nicola; Quintal, Beatriz

    2013-10-01

    A novel laboratory technique is proposed to investigate wave-induced fluid flow on the mesoscopic scale as a mechanism for seismic attenuation in partially saturated rocks. This technique combines measurements of seismic attenuation in the frequency range from 1 to 100 Hz with measurements of transient fluid pressure as a response of a step stress applied on top of the sample. We used a Berea sandstone sample partially saturated with water. The laboratory results suggest that wave-induced fluid flow on the mesoscopic scale is dominant in partially saturated samples. A 3-D numerical model representing the sample was used to verify the experimental results. Biot's equations of consolidation were solved with the finite-element method. Wave-induced fluid flow on the mesoscopic scale was the only attenuation mechanism accounted for in the numerical solution. The numerically calculated transient fluid pressure reproduced the laboratory data. Moreover, the numerically calculated attenuation, superposed to the frequency-independent matrix anelasticity, reproduced the attenuation measured in the laboratory in the partially saturated sample. This experimental-numerical fit demonstrates that wave-induced fluid flow on the mesoscopic scale and matrix anelasticity are the dominant mechanisms for seismic attenuation in partially saturated Berea sandstone.

  20. Spatial and Temporal Variations in the Partial Pressure and Emission of CO2 and CH4 in and Amazon Floodplain Lake

    NASA Astrophysics Data System (ADS)

    Forsberg, B. R.; Amaral, J. H.; Barbosa, P.; Kasper, D.; MacIntyre, S.; Cortes, A.; Sarmento, H.; Borges, A. V.; Melack, J. M.; Farjalla, V.

    2015-12-01

    The Amazon floodplain contains a variety of wetland environments which contribute CO2 and CH4 to the regional and global atmospheres. The partial pressure and emission of these greenhouse gases (GHGs) varies: 1) between habitats, 2) seasonally, as the characteristics these habitats changes and 3) diurnally, in response to diurnal stratification. In this study, we investigated the combined influence of these factors on the partial pressure and emission of GHGs in Lago Janauacá, a central Amazon floodplain lake (3o23' S; 60o18' O). All measurements were made between August of 2014 and April of 2015 at two different sites and in three distinct habitats: open water, flooded forest, flooded macrophytes. Concentrations of CO2 and CH4 in air were measured continuously with a cavity enhanced absorption spectrometer, Los Gatos Research´s Ultraportable Greenhouse Gas Analyzer (UGGA). Vertical profiles o pCO2 and pCH4 were measured using the UGGA connected to an electric pump and equilibrator. Diffusive surface emissions were estimated with the UGGA connected to a static floating chamber. To investigate the influence of vertical stratification and mixing on GHG partial pressure and emissions, a meteorological station and submersible sensor chain were deployed at each site. Meteorological sensors included wind speed and direction. The submersible chains included thermistors and oxygen sensors. Depth profiles of partial pressure and diffusive emissions for both CO2 and CH4 varied diurnally, seasonally and between habitats. Both pCO2 and pCH4 were consistently higher in bottom than surface waters with the largest differences occurring at high water when thermal stratification was most stable. Methane emissions and partial pressures were highest at low water while pCO2 and CO2 fluxes were highest during high water periods, with 35% of CO2 fluxes at low water being negative. The highest average surface value of pCO2 (5491 μatm), encountered during rising water, was ~3 times

  1. A new measuring device for non-invasive determination of oxygen partial pressure and oxygen conductance of the skin and other tissues.

    PubMed

    Niehoff, K; Barnikol, W K

    1999-01-01

    About fifty percent of the oxygen consumption of the skin is supplied by diffusion through the surface. This portion of the skin oxygen supply becomes of high importance in case of arterial occlusion. The oxygen permeation coefficient (P) of the upper layers and the oxygen pressure field within the skin determine the diffusive oxygen uptake from the outside. To our knowledge, the permeation coefficient (P) until now was only estimated by indirect methods of little practicability (Baumberger et al., 1951; Eberhard et al., 1978). An oxygen partial pressure of the skin is conventionally measured by modified CLARK type electrodes. A disadvantage of this so-called transcutaneous electrode is its oxygen consumption and the fixed coupling of the consumption with the oxygen pressure to be determined. Therefore the measurement always induces a systematic error (the so-called stirring effect) which depends, among other factors, on the oxygen availability of the skin under the electrode. The new device combines a consumption-free oxygen partial pressure detector on the basis of luminescence quenching by oxygen with an independently working specific oxygen consumer realized by an active galvanic chain (silver-lead element). The chain permits setting any oxygen mass flow (mO2) in a certain range by varying the electrode current choosing different resistors within the electrical circuit. According to the diffusion law, the surface oxygen pressure (ePO2) being measured is a linear function of the oxygen flow (mO2) directed to the cathode: ePO2 identical to -(1/P).(mO2/A) + icPO2; A: area under the cathode. The intracutaneous oxygen partial pressure (icPO2) is a virtual quantity defined by the equation given. Only by using an active electrode different oxygen mass flows can be set and so the oxygen conductance of the upper skin layers can be assessed. First experiments on human skin in the gluteal region of an adult delivered an estimated value of the permeation coefficient (P): 2

  2. Chemistry and properties of blends of acetylene terminated materials

    NASA Technical Reports Server (NTRS)

    Connell, John W.; Hergenrother, Paul M.

    1991-01-01

    As part of a NASA program to develop new high temperature/high performance structural materials, the chemistry and properties of acetylene-containing materials and their cured resins are under investigation. The objective of this work is to develop materials that are readily processable (i.e., 200-300 C and about 1.4 MPa or less) and possess usable mechanical properties at temperatures as high as 177 C. An acetylene-terminated aspartimide (ATA) was blended with an equal weight of an acetylene-terminated arylene ether (ATAE) oligomer. The blend was subsequently thermally cured to yield a resin which was evaluated in the form of neat resin moldings, adhesive specimens, and laminates. Adhesive specimens and laminates gave good mechanical properties to temperatures as high as 177 C. In addition, preliminary laminate work is presented on the resin from a blend of a new N-methyl substituted ATA and an ATAE.

  3. Microgravity Superagglomerates Produced By Silane And Acetylene

    NASA Technical Reports Server (NTRS)

    Gokoglu, Suleyman (Technical Monitor); Bundy, Matthew; Mulholland, George W.; Manzello, Samuel; Yang, Jiann; Scott, John Henry; Sivathanu, Yudaya

    2003-01-01

    The size of the agglomerates produced in the upper portion of a flame is important for a variety of applications. Soot particle size and density effect the amount of radiative heat transfer from a fire to its surroundings. Particle size determines the lifetime of smoke in a building or in the atmosphere, and exposure hazard for smoke inhaled and deposited in the lungs. The visibility through a smoke layer and dectectability of the smoke are also greatly affected by agglomerate size. Currently there is limited understanding of soot growth with an overall dimension of 10 m and larger. In the case of polystyrene, smoke agglomerates in excess of 1 mm have been observed raining out from large fires. Unlike hydrocarbon fuels, silane has the advantage that silica particles are the major combustion product resulting in a particle volume fraction a factor of ten greater than that for a carbonaceous smoke. There are two very desirable properties of silica aero-gels that are important for both space and earth based applications. The first important property is its inertness to most oxidizing and reducing atmospheres. Therefore, silica aero-gels make excellent fire ablatives and can be used in very demanding applications. The second important property is that silica aero-gels are expected to have very high porosity (greater than 0.999), making them lightweight and ideal for aerospace applications. The added benefit of the high porosity is that they can be used as extremely efficient filters for many earth based applications as well. Evidence of the formation of superagglomerates in a laminar acetylene/air diffusion flame was found by Sorensen et al. [1]. An interconnecting web of super-agglomerates was observed to span the width of the soot plume in the region just above the flame tip and described as a gel state. It was observed that this gel state immediately breaks up into agglomerates as larges as 100 m due to buoyancy induced turbulence. Large soot agglomerates were

  4. Long-term spatial and temporal variation of CO2 partial pressure in the Yellow River, China

    NASA Astrophysics Data System (ADS)

    Ran, L.; Lu, X. X.; Richey, J. E.; Sun, H.; Han, J.; Yu, R.; Liao, S.; Yi, Q.

    2015-02-01

    Carbon transport in river systems is an important component of the global carbon cycle. Most rivers of the world act as atmospheric CO2 sources due to high riverine CO2 partial pressure (pCO2). By determining the pCO2 from alkalinity and pH, we investigated its spatial and temporal variation in the Yellow River watershed using historical water chemistry records (1950s-1984) and recent sampling along the mainstem (2011-2012). Except the headwater region where the pCO2 was lower than the atmospheric equilibrium (i.e. 380 μatm), river waters in the remaining watershed were supersaturated with CO2. The average pCO2 for the watershed was estimated at 2810 ± 1985 μatm, which is 7-fold the atmospheric equilibrium. As a result of severe soil erosion and dry climate, waters from the Loess Plateau in the middle reaches had higher pCO2 than that from the upper and lower reaches. From a seasonal perspective, the pCO2 varied from about 200 μatm to > 30 000 μatm with higher pCO2 usually occurring in the dry season and lower pCO2 in the wet season (at 73% of the sampling sites), suggesting the dilution effect of water. While the pCO2 responded exponentially to total suspended solids (TSS) export when the TSS concentration was less than 100 kg m-3, it decreased slightly and remained stable if the TSS concentration exceeded 100 kg m-3. This stable pCO2 is largely due to gully erosion that mobilizes subsoils characterized by low organic carbon for decomposition. In addition, human activities have changed the pCO2 dynamics. Particularly, flow regulation by dams can diversely affect the temporal changes of pCO2, depending on the physiochemical properties of the regulated waters and adopted operation scheme. Given the high pCO2 in the Yellow River waters, large potential for CO2 evasion is expected and warrants further investigation.

  5. [Partial pressure of CO2 and CO2 degassing fluxes of Huayuankou and Xiaolangdi Station affected by Xiaolangdi Reservoir].

    PubMed

    Zhang, Yong-ling; Yang, Xiao-lin; Zhang, Dong

    2015-01-01

    According to periodic sampling analysis per month in Xiaolangdi station and Huayuankou station from November 2011 to October 2012, combined with continuous sampling analysis of Xiaolangdi Reservoir during runoff and sediment control period in 2012, partial pressure of CO2 (pCO2) in surface water were calculated based on Henry's Law, pCO2 features and air-water CO2 degassing fluxes of Huayuankou station and Xiaolangdi station affected by Xiaolangdi Reservoir were studied. The results were listed as follows, when Xiaolangdi Reservoir operated normally, pCO2 in surface water of Xiaolangdi station and Huayuankou station varied from 82 to 195 Pa and from 99 to 228 Pa, moreover, pCO2 in surface water from July to September were distinctly higher than those in other months; meanwhile, pCO, in surface water from Huayuankou station were higher than that from Xiaolangdi station. During runoff and sediment control period of Xiaolangdi Reservoir, two hydrological stations commonly indicated that pCO2 in surface water during water draining were obviously lower than those during sediment releasing. Whether in the period of normal operation or runoff and sediment control, pCO2 in surface water had positive relations to DIC content in two hydrological stations. Since the EpCO,/AOU value was higher than the theoretical value of 0. 62, the biological aerobic respiration effect had distinct contribution to pCO2. Throughout the whole year, air-water CO2 degassing fluxes from Xiaolangdi station and Huayuankou station were 0.486 p.mol (m2 s) -l and 0.588 pmol (m2 x s)(-1) respectively; When Xiaolangdi Reservoir operated normally, air-water CO, degassing fluxes in Huayuankou station were higher than that in Xiaolangdi station; during runoff and sediment control from Xiaolangdi Reservoir, two hydrological stations had one observation result in common, namely, air-water CO2 degassing fluxes in the period of water draining were obviously lower than that in the period of sediment releasing

  6. Biomethanation of Syngas Using Anaerobic Sludge: Shift in the Catabolic Routes with the CO Partial Pressure Increase.

    PubMed

    Sancho Navarro, Silvia; Cimpoia, Ruxandra; Bruant, Guillaume; Guiot, Serge R

    2016-01-01

    Syngas generated by thermal gasification of biomass or coal can be steam reformed and purified into methane, which could be used locally for energy needs, or re-injected in the natural gas grid. As an alternative to chemical catalysis, the main components of the syngas (CO, CO2, and H2) can be used as substrates by a wide range of microorganisms, to be converted into gas biofuels, including methane. This study evaluates the carboxydotrophic (CO-consuming) methanogenic potential present in an anaerobic sludge from an upflow anaerobic sludge bed (UASB) reactor treating waste water, and elucidates the CO conversion routes to methane at 35 ± 3°C. Kinetic activity tests under CO at partial pressures (pCO) varying from 0.1 to 1.5 atm (0.09-1.31 mmol/L in the liquid phase) showed a significant carboxydotrophic activity potential for growing conditions on CO alone. A maximum methanogenic activity of 1 mmol CH4 per g of volatile suspended solid and per day was achieved at 0.2 atm of CO (0.17 mmol/L), and then the rate decreased with the amount of CO supplied. The intermediary metabolites such as acetate, H2, and propionate started to accumulate at higher CO concentrations. Inhibition experiments with 2-bromoethanesulfonic acid (BES), fluoroacetate, and vancomycin showed that in a mixed culture CO was converted mainly to acetate by acetogenic bacteria, which was further transformed to methane by acetoclastic methanogens, while direct methanogenic CO conversion was negligible. Methanogenesis was totally blocked at high pCO in the bottles (≥1 atm). However it was possible to achieve higher methanogenic potential under a 100% CO atmosphere after acclimation of the sludge to CO. This adaptation to high CO concentrations led to a shift in the archaeal population, then dominated by hydrogen-utilizing methanogens, which were able to take over acetoclastic methanogens, while syntrophic acetate oxidizing (SAO) bacteria oxidized acetate into CO2 and H2. The disaggregation of the

  7. Biomethanation of Syngas Using Anaerobic Sludge: Shift in the Catabolic Routes with the CO Partial Pressure Increase

    PubMed Central

    Sancho Navarro, Silvia; Cimpoia, Ruxandra; Bruant, Guillaume; Guiot, Serge R.

    2016-01-01

    Syngas generated by thermal gasification of biomass or coal can be steam reformed and purified into methane, which could be used locally for energy needs, or re-injected in the natural gas grid. As an alternative to chemical catalysis, the main components of the syngas (CO, CO2, and H2) can be used as substrates by a wide range of microorganisms, to be converted into gas biofuels, including methane. This study evaluates the carboxydotrophic (CO-consuming) methanogenic potential present in an anaerobic sludge from an upflow anaerobic sludge bed (UASB) reactor treating waste water, and elucidates the CO conversion routes to methane at 35 ± 3°C. Kinetic activity tests under CO at partial pressures (pCO) varying from 0.1 to 1.5 atm (0.09–1.31 mmol/L in the liquid phase) showed a significant carboxydotrophic activity potential for growing conditions on CO alone. A maximum methanogenic activity of 1 mmol CH4 per g of volatile suspended solid and per day was achieved at 0.2 atm of CO (0.17 mmol/L), and then the rate decreased with the amount of CO supplied. The intermediary metabolites such as acetate, H2, and propionate started to accumulate at higher CO concentrations. Inhibition experiments with 2-bromoethanesulfonic acid (BES), fluoroacetate, and vancomycin showed that in a mixed culture CO was converted mainly to acetate by acetogenic bacteria, which was further transformed to methane by acetoclastic methanogens, while direct methanogenic CO conversion was negligible. Methanogenesis was totally blocked at high pCO in the bottles (≥1 atm). However it was possible to achieve higher methanogenic potential under a 100% CO atmosphere after acclimation of the sludge to CO. This adaptation to high CO concentrations led to a shift in the archaeal population, then dominated by hydrogen-utilizing methanogens, which were able to take over acetoclastic methanogens, while syntrophic acetate oxidizing (SAO) bacteria oxidized acetate into CO2 and H2. The disaggregation of the

  8. Partial pressure of CO2 and CO2 emission in a monsoon-driven hydroelectric reservoir (Danjiangkou Reservoir), China

    NASA Astrophysics Data System (ADS)

    Li, S. Y.; Zhang, Q. F.

    2013-06-01

    Hydroelectric reservoirs have been under sampled to establish them as sources or sinks of the atmospheric carbon dioxide (CO2). Such poor coverage is well known for subtropic, particularly monsoon driven reservoirs in China. Our study presented the spatiotemporal changes of the carbonate system and CO2 flux in a hydroelectric reservoir (Dangjiankou Reservoir) locating in a subtropical monsoon climate region. Our 21 filed surveys conducted during 2004-2011 revealed significantly spatial and monthly variations of surface water partial pressure of CO2 (pCO2) in the Reservoir. pCO2, showing higher concentrations in the wet and warm seasons, averaged 595 ± 545 µatm (ranging from 53-3751 µatm) in the reservoir surface, while substantially higher pCO2 (1132 ± 1220 µatm) was observed in the river downstream the dam. A clear pCO2 drawdown in the reservoir as water flows demonstrated a significantly descending order of Dan Reservoir > site close to dam > Han Reservoir. This spatial contrast can also be seen in the distributions of dissolved inorganic carbon and total alkalinity. Pronounced seasonality in pCO2 was controlled by seasonal monsoon rainfall, while photosynthetic CO2 uptake dominated spatial patterns and dry-month variability of pCO2. We further related pCO2 to water chemical properties and indicated that pCO2 had strong positive correlations with Si, TP and DOC, negative correlations with DO saturation, TN and Chl a, while weak correlations with other variables including biogenic elements. CO2 flux from the Reservoir surface showed a bottom average of 9 mmol m-2 d-2 in comparison with other hydroelectric reservoir in China. River downstream the dam had quite high flux of CO2 (119 mmol m-2 d-2), which was intermediate between temperate rivers and compared to global rivers' average. This means that water releasing from reservoir would be an important channel for atmospheric CO2 sources. The annual CO2 emission from the Danjiangkou Reservoir was estimated to be

  9. Changes in partial pressures of respiratory gases during submerged voluntary breath hold across odontocetes: is body mass important?

    PubMed

    Noren, S R; Williams, T M; Ramirez, K; Boehm, J; Glenn, M; Cornell, L

    2012-02-01

    Odontocetes have an exceptional range in body mass spanning 10(3) kg across species. Because, size influences oxygen utilization and carbon dioxide production rates in mammals, this lineage likely displays an extraordinary variation in oxygen store management compared to other marine mammal groups. To examine this, we measured changes in the partial pressures of respiratory gases ([Formula: see text], [Formula: see text]), pH, and lactate in the blood during voluntary, quiescent, submerged breath holds in Pacific white-sided dolphins (Lagenorhynchus obliquidens), bottlenose dolphins (Tursiops truncatus), and a killer whale (Orcinus orca) representing a mass range of 96-3,850 kg. These measurements provided an empirical determination of the effect of body size on the variability in blood biochemistry during breath hold and experimentally determined aerobic dive limits (ADL) within one taxonomic group (odontocetes). For the species in this study, maximum voluntary breath-hold duration was positively correlated with body mass, ranging from 3.5 min in white-sided dolphins to 13.3 min for the killer whale. Variation in breath-hold duration was associated with differences in the rate of change for [Formula: see text] throughout breath hold; [Formula: see text] decreased twice as fast for the two smaller species (-0.6 mmHg O(2) min(-1)) compared to the largest species (-0.3 mmHg O(2) min(-1)). In contrast, the rate of increase in [Formula: see text] during breath hold was similar across species. These results demonstrate that large body size in odontocetes facilitates increased aerobic breath-hold capacity as mediated by decreased mass-specific metabolic rates (rates of change in [Formula: see text] served as a proxy for oxygen utilization). Indeed the experimentally determined 5 min ADL for bottlenose dolphins was surpassed by the 13.3 min maximum breath hold of the killer whale, which did not end in a rise in lactate. Rather, breath hold ended voluntarily as respiratory

  10. Oxygen partial pressure dependence of magnetic, optical and magneto-optical properties of epitaxial cobalt-substituted SrTiO₃ films.

    PubMed

    Onbaşlı, Mehmet C; Goto, Taichi; Tang, Astera; Pan, Annia; Battal, Enes; Okyay, Ali K; Dionne, Gerald F; Ross, C A

    2015-05-18

    Cobalt-substituted SrTiO3 films (SrTi0.70Co0.30O(3-δ)) were grown on SrTiO3 substrates using pulsed laser deposition under oxygen pressures ranging from 1 μTorr to 20 mTorr. The effect of oxygen pressure on structural, magnetic, optical, and magneto-optical properties of the films was investigated. The film grown at 3 μTorr has the highest Faraday rotation (FR) and magnetic saturation moment (M(s)). Increasing oxygen pressure during growth reduced M(s), FR and optical absorption in the near-infrared. This trend is attributed to decreasing Co2+ ion concentration and oxygen vacancy concentration with higher oxygen partial pressure during growth. PMID:26074589

  11. Siloxane containing addition polyimides. II - Acetylene terminated polyimides

    NASA Technical Reports Server (NTRS)

    Maudgal, S.; St. Clair, T. L.

    1984-01-01

    Acetylene terminated polyimide oligomers having a range of molecular weights have been synthesized by reacting bis (gamma-aminopropyl) tetramethyldisiloxane, aminophenylacetylene and 3, 3', 4, 4' benzophenonetetracarboxylic dianhydride in different molar ratios. The prepolymers were isolated and characterized for melt flow and cure properties. They show promise as adhesives for bonding titanium to titanium and as matrix resins for graphite cloth reinforced composites. The most promising system has been blended in varying proportions with Thermid 600, a commercially available acetylene terminated polyimide oligomer, and the mixtures have been tested for application as composite matrix resins.

  12. Acetylene, a mammalian metabolite of 1,1,1-trichloroethane.

    PubMed

    Dürk, H; Poyer, J L; Klessen, C; Frank, H

    1992-09-01

    1,1,1-Trichloroethane (TCE) is a widely used industrial solvent of low acute toxicity. It is slowly oxidized to trichloroethanol and trichloroacetic acid by cytochrome P-450-dependent mono-oxygenases. Increased inhalative uptake by rats under hypoxia and spin-trapping experiments indicate that TCE is also reductively metabolized to a radical intermediate. Acetylene is formed as a metabolite, suggesting transfer of an additional electron to form the corresponding carbene. Hypoxia and induction of mixed-function mono-oxygenases accelerate the formation of acetylene. Experiments performed in vitro with rat liver microsomal fractions yield analogous results. PMID:1326938

  13. Synthesis of functional acetylene derivatives from calcium carbide.

    PubMed

    Lin, Zhewang; Yu, Dingyi; Sum, Yin Ngai; Zhang, Yugen

    2012-04-01

    AHA Erlebnis: CaC(2), used to produce acetylene until several decades ago, is re-emerging as a cheap, sustainable resource synthesized from coal and lignocellulosic biomass. We report efficient catalytic protocols for the synthesis of functional acetylene derivatives from CaC(2) through aldehyde, alkyne, and amine (AAA) as well as alkyne, haloalkane, and amine (AHA) couplings, and in addition demonstrate its use in click and Sonogashira chemistry, showing that calcium carbide is a sustainable and cost-efficient carbon source. PMID:22378645

  14. Channel-resolved above-threshold double ionization of acetylene.

    PubMed

    Gong, Xiaochun; Song, Qiying; Ji, Qinying; Lin, Kang; Pan, Haifeng; Ding, Jingxin; Zeng, Heping; Wu, Jian

    2015-04-24

    We experimentally investigate the channel-resolved above-threshold double ionization (ATDI) of acetylene in the multiphoton regime using an ultraviolet femtosecond laser pulse centered at 395 nm by measuring all the ejected electrons and ions in coincidence. As compared to the sequential process, diagonal lines in the electron-electron joint energy spectrum are observed for the nonsequential ATDI owing to the correlative sharing of the absorbed multiphoton energies. We demonstrate that the distinct channel-resolved sequential and nonsequential ATDI spectra can clearly reveal the photon-induced acetylene-vinylidene isomerization via proton migration on the cation or dication states. PMID:25955049

  15. Extended x-ray absorption fine structure measurements on radio frequency magnetron sputtered HfO2 thin films deposited with different oxygen partial pressures.

    PubMed

    Maidul Haque, S; Nayak, C; Bhattacharyya, Dibyendu; Jha, S N; Sahoo, N K

    2016-03-20

    Two sets of HfO2 thin film have been deposited by the radio frequency magnetron sputtering technique at various oxygen partial pressures, one set without any substrate bias and another set with a 50 W pulsed dc substrate bias. The films have been characterized by extended x-ray absorption fine structure (EXAFS) measurements at the Hf L3 edge, and the structural information obtained from analysis of the EXAFS data has been used to explain the macroscopic behavior of the refractive index obtained from spectroscopic ellipsometry measurements. It has been observed that the variation of refractive index with oxygen partial pressure depends on the Hf-Hf bond length for the set of films deposited without substrate bias, while for the other set of films deposited with pulsed dc substrate bias, it depends on the oxygen coordination of the nearest neighbor shell surrounding Hf sites. PMID:27140550

  16. Enhanced Shrinkage of Lanthanum Strontium Manganite (La0.90Sr0.10MnO3+δ) Resulting from Thermal and Oxygen Partial Pressure Cycling

    SciTech Connect

    McCarthy, Ben; Pederson, Larry R.; Anderson, Harlan U.; Zhou, Xiao Dong; Singh, Prabhakar; Coffey, Greg W.; Thomsen, Ed C.

    2007-10-01

    Exposure of La0.9Sr0.1MnO3+δ to repeated oxygen partial pressure cycles (air/10 ppm O2) resulted in enhanced densification rates, similar to behavior shown previously due to thermal cycling. Shrinkage rates in the temperature range 700 to 1000oC were orders of magnitude higher than Makipirtti-Meng model estimations based on stepwise isothermal dilatometry results at high temperature. A maximum in enhanced shrinkage due to oxygen partial pressure cycling occurred at 900oC. Shrinkage was greatest when LSM-10 bars that were first equilibrated in air were exposed to gas flows of lower oxygen fugacity than in the reverse direction. The former creates transient cation and oxygen vacancies well above the equilibrium concentration, resulting in enhanced mobility. These vacancies annihilate as Schottky equilibria is re-established, whereas the latter condition does not lead to excess vacancy concentrations.

  17. [Generation of Superoxide Radicals by Complex III in Heart Mitochondria and Antioxidant Effect of Dinitrosyl Iron Complexes at Different Partial Pressure of Oxygen].

    PubMed

    Dudylina, A L; Ivanova, M V; Shumaev, K B; Ruuge, E K

    2016-01-01

    The EPR spin-trapping technique and EPR-oximetry were used to study generation of superoxide radicals in heart mitochondria isolated from Wistar rats under conditions of variable oxygen concentration. Lithium phthalocyanine and TEMPONE-15N-D16 were chosen to determine oxygen content in a gas-permeable capillary tube containing mitochondria. TIRON was used as a spin trap. We investigated the influence of different oxygen concentrations in incubation mixture and demonstrated that heart mitochondria can generate superoxide in complex III at different partial pressure of oxygen as well as under the conditions of deep hypoxia (< 5% O2). Dinitrosyl iron complexes with glutathione (the pharmaceutical drug "Oxacom") exerted an antioxidant effect, regardless of the value of the partial pressure of oxygen, but the magnitude and kinetic characteristics of the effect depended on the concentration of the drug. PMID:27192832

  18. Precise and high-speed control of partial pressures of multiple gas species in plasma process chamber using pulse-controlled gas injection

    SciTech Connect

    Morishita, Sadaharu; Goto, Tetsuya; Nagase, Masaaki; Ohmi, Tadahiro

    2009-05-15

    Multiprocesses in a single plasma process chamber with high throughput require precise, sequential, high-speed alteration of partial pressures of multiple gas species. A conventional gas-distribution system cannot realize this because the system seriously overshoots gas pressure immediately following valve operation. Furthermore, chamber volume and conductance of gas piping between the system and chamber should both be considered because they delay the stabilizing time of gas pressure. Therefore, the authors proposed a new gas-distribution system without overshoot by controlling gas flow rate based on pressure measurement, as well as a method of pulse-controlled gas injection immediately following valve operation. Time variation of measured partial pressure agrees well with a calculation based on an equivalent-circuit model that represents the chamber and gas piping between the system and chamber. Using pulse-controlled gas injection, the stabilizing time can be reduced drastically to 0.6 s for HBr added to pure Ar plasma, and 0.7 s for O{sub 2} added to Ar/HBr plasma; without the pulse control, the stabilizing times are 3 and 7 s, respectively. In the O{sub 2} addition case, rapid stabilization can be achieved during the period of line/space pattern etching of poly-Si on a thin SiO{sub 2} film. This occurs without anomalous etching of the underlying SiO{sub 2} film or the Si substrate near the sidewall, thus obtaining a wide process margin with high throughput.

  19. Calculation of the thermodynamic and transport properties of aqueous species at high pressures and temperatures: Standard partial molal properties of inorganic neutral species

    NASA Astrophysics Data System (ADS)

    Shock, Everett L.; Helgeson, Harold C.; Sverjensky, Dimitri A.

    1989-09-01

    Consideration of interactions between neutral aqueous species and H 2O dipoles in terms of effective Born coefficients permits extension of the revised HKF (Helgeson, Kirkham and Flowers, 1981) equations of state (Tanger and Helgeson, 1988) for the standard partial molal properties of ionic species at high pressures and temperatures to include inorganic gases, acids, and other neutral aqueous species. Correlation algorithms similar to those used to estimate equation of state parameters for ions and electrolytes ( SHOCK, and Helgeson, 1988) have also been developed for neutral aqueous species. Calculation of the standard partial molal thermodynamic properties of dissolved inorganic gases as well as other neutral aqueous species as a function of pressure and temperature indicates that the standard partial molal volume (V¯ 0), heat capacity (C¯ 0p), and entropy (S¯ 0), together with the apparent standard partial molal enthalpy of formation (ΔH¯ 0) of many of these species in the liquid phase minimize with increasing temperature at P SAT and approach ∞ at the critical point of H 2O. In the case of other neutral aqueous species such as SiO 2(aq), V¯0, C¯0p, S¯0, and Δ H¯0 behave as functions of temperature and pressure like those of electrolytes in the liquid phase and maximize with increasing temperature at P SAT, approaching - ∞ at the critical point of H 2O. Which of these types of behavior is exhibited by V¯0, C¯)p, S¯0, and Δ H¯0 for a given neutral aqueous species depends in part on the relative volatility of the aqueous species and the effect of the species on solvent dipole-dipole interaction. Close agreement between predicted and experimentally determined equilibrium constants for gas solubility and inorganic acid dissociation reactions at high temperatures and pressures supports the validity and generality of the equations of state and the predictive algorithms. High temperature/pressure equilibrium constants can be predicted for reactions

  20. Selective modulation of cellular voltage-dependent calcium channels by hyperbaric pressure-a suggested HPNS partial mechanism.

    PubMed

    Aviner, Ben; Gradwohl, Gideon; Mor Aviner, Merav; Levy, Shiri; Grossman, Yoram

    2014-01-01

    Professional deep sea divers experience motor and cognitive impairment, known as High Pressure Neurological Syndrome (HPNS), when exposed to pressures of 100 msw (1.1 MPa) and above, considered to be the result of synaptic transmission alteration. Previous studies have indicated modulation of presynaptic Ca(2+) currents at high pressure. We directly measured for the first time pressure effects on the currents of voltage dependent Ca(2+) channels (VDCCs) expressed in Xenopus oocytes. Pressure selectivity augmented the current in CaV1.2 and depressed it in CaV3.2 channels. Pressure application also affected the channels' kinetics, such as ƮRise, ƮDecay. Pressure modulation of VDCCs seems to play an important role in generation of HPNS signs and symptoms. PMID:24904281

  1. 46 CFR 56.50-103 - Fixed oxygen-acetylene distribution piping.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Fixed oxygen-acetylene distribution piping. 56.50-103... oxygen-acetylene distribution piping. (a) This section applies to fixed piping installed for the distribution of oxygen and acetylene carried in cylinders as vessels stores. (b) The distribution piping...

  2. 46 CFR 56.50-103 - Fixed oxygen-acetylene distribution piping.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Fixed oxygen-acetylene distribution piping. 56.50-103... oxygen-acetylene distribution piping. (a) This section applies to fixed piping installed for the distribution of oxygen and acetylene carried in cylinders as vessels stores. (b) The distribution piping...

  3. 46 CFR 56.50-103 - Fixed oxygen-acetylene distribution piping.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Fixed oxygen-acetylene distribution piping. 56.50-103... oxygen-acetylene distribution piping. (a) This section applies to fixed piping installed for the distribution of oxygen and acetylene carried in cylinders as vessels stores. (b) The distribution piping...

  4. 46 CFR 56.50-103 - Fixed oxygen-acetylene distribution piping.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Fixed oxygen-acetylene distribution piping. 56.50-103... oxygen-acetylene distribution piping. (a) This section applies to fixed piping installed for the distribution of oxygen and acetylene carried in cylinders as vessels stores. (b) The distribution piping...

  5. 46 CFR 56.50-103 - Fixed oxygen-acetylene distribution piping.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Fixed oxygen-acetylene distribution piping. 56.50-103... oxygen-acetylene distribution piping. (a) This section applies to fixed piping installed for the distribution of oxygen and acetylene carried in cylinders as vessels stores. (b) The distribution piping...

  6. [Effect of oxygen partial pressure on the band-gap of the TiO2 films prepared by DC reactive sputtering].

    PubMed

    Zhao, Qing-nan; Li, Chun-ling; Liu, Bao-shun; Zhao, Xiu-jian

    2004-05-01

    TiO2 films have been deposited on glass substrates using DC reactive magnetron sputtering at different oxygen partial pressures from 0.10 to 0.65 Pa. The photoluminescence (PL) spectra of the films were recorded. The results of the PL spectra showed that there were three emission peaks at 370, 472 and 514 nm for the films sputtered at 0.35 and 0.65 Pa, and there were two peaks at 370 and 490 nm for the films sputtered at 0.10 and 0.15 Pa. The band-gap for the films was 3.35 eV. For the films sputtered at 0.35 and 0.65 Pa there were two defect energy levels at 2.63 and 2.41 eV, corresponding to 0.72 and 0.94 eV below conduction band for the band-gap, respectively. For the films sputtered at 0.10 and 0.15 Pa, there was an energy band formed between 3.12 and 2.06 eV, corresponding to 0.23 and 1.29 eV below the conduction band. With increasing the oxygen partial pressure, the defect energy band changed to two energy levels, and the energy levels nearly disappeared for the film sputtered at 0.65 Pa of oxygen partial pressure. PMID:15769058

  7. Composition-Temperature-Partial Pressures Data for Cd(sub 0.8)Zn(sub 0.2)Te by Optical Absorption Measurements

    NASA Technical Reports Server (NTRS)

    Su, Ching-Hua

    2005-01-01

    Known weights of Cd, Zn and Te were reacted in silica optical cells of known volume and the partial pressure of Te2 and Zn between 485 and 1160 C were determined by measuring the optical density of the vapor in the ultra-violet to visible range. The composition of the condensed phase or phases was calculated from the original weights and the amount of material in the vapor phase. The corresponding composition - temperature - partial pressures, x(sub Te)-T-P(sub Te2), data, including five Te-rich solidus points, were established. The solubility range for the Te-rich Cd(sub 0.8)Zn(sub 0.2)Te(s) is similar to that of CdTe(s) with x(sub Te) = 0.50005 at 809 C and an estimated maximum solubility of x(sub Te) = 0.50012 at about 1000 C. The partial pressure of Cd and Te(sub 2) measured over the Cd(sub 0.8)Zn(sub 0.2)Te melt at 1140 C were about 1.55 and 0.02 atm, respectively, and the corresponding P(Sub Zn) was estimated to be 0.05 atm. It was recommended that a Cd reservoir maintaining at 800 to 820 C should be used during directional solidification of Cd(sub o.8)Zn(sub 0.2)Te to prevent the preferential loss of Cd to the vapor phase.

  8. Effects of various oxygen partial pressures on Ti-doped ZnO thin film transistors fabricated on flexible plastic substrate

    NASA Astrophysics Data System (ADS)

    Cui, Guodong; Han, Dedong; Yu, Wen; Shi, Pan; Zhang, Yi; Huang, Lingling; Cong, Yingying; Zhou, Xiaoliang; Zhang, Xiaomi; Zhang, Shengdong; Zhang, Xing; Wang, Yi

    2016-04-01

    By applying a novel active layer of titanium zinc oxide (TiZO), we have successfully fabricated fully transparent thin-film transistors (TFTs) with a bottom gate structure fabricated on a flexible plastic substrate at low temperatures. The effects of various oxygen partial pressures during channel deposition were studied to improve the device performance. We found that the oxygen partial pressure during channel deposition has a significant impact on the performance of TiZO TFTs, and that the TFT developed under 10% oxygen partial pressure exhibits superior performance with a low threshold voltage (V th) of 2.37 V, a high saturation mobility (μsat) of 125.4 cm2 V-1 s-1, a steep subthreshold swing (SS) of 195 mV/decade and a high I on/I off ratio of 3.05 × 108. These results suggest that TiZO thin films are promising for high-performance fully transparent flexible TFTs and displays.

  9. Vacuum ultra-violet emission of plasma discharges with high Xe partial pressure using a cathode protective layer with high secondary electron emission

    SciTech Connect

    Zhu, Di; Song, Le; Zhang, Xiong; Kajiyama, Hiroshi

    2014-02-14

    In this work, the mechanism of the vacuum ultra-violet (VUV) emission of plasma discharges, with high Xe partial pressure and high ion-induced secondary electrons emission protective layer, is studied by measuring the VUV light emission directly and comparing it with two-dimensional simulations. From the panel measurement, we find that the high intensity of excimer VUV mainly contributes to the high luminous efficacy of SrCaO-plasma display panels (PDP) at a low sustain voltage. The unchanged Xe excitation efficiency indicates that the electron temperature is not decreased by the high secondary electrons emission protective layer, even though the sustain voltage is much lower. From the two-dimensional simulations, we can find that the ratio of excimer VUV to resonant VUV, which is determined by the collision rate in the discharge, is only significantly affected by the Xe partial pressure, while it is independent of the sustain voltage and the secondary-electrons-emission capability of protective layer. The unchanged average electron energy at the moment when the electric field becomes maximum confirms that the improvement of the VUV production efficiency mainly is attributed to the increase in electron heating efficiency of a PDP with high ion-induced secondary electrons emission protective layer. Combining the experimental and the simulation results, we conclude about the mechanism by which the VUV production is improved for the plasma display panel with a high Xe partial pressure and a cold cathode with high ion-induced secondary electrons emission.

  10. Ultra smooth NiO thin films on flexible plastic (PET) substrate at room temperature by RF magnetron sputtering and effect of oxygen partial pressure on their properties

    NASA Astrophysics Data System (ADS)

    Nandy, S.; Goswami, S.; Chattopadhyay, K. K.

    2010-03-01

    Transparent p-type nickel oxide thin films were grown on polyethylene terephthalate (PET) and glass substrates by RF magnetron sputtering technique in argon + oxygen atmosphere with different oxygen partial pressures at room temperature. The morphology of the NiO thin films grown on PET and glass substrates was studied by atomic force microscope. The rms surface roughnesses of the films were in the range 0.63-0.65 nm. These ultra smooth nanocrystalline NiO thin films are useful for many applications. High resolution transmission electron microscopic studies revealed that the grains of NiO films on the highly flexible PET substrate were purely crystalline and spherical in shape with diameters 8-10 nm. XRD analysis also supported these results. NiO films grown on the PET substrates were found to have better crystalline quality with fewer defects than those on the glass substrates. The sheet resistances of the NiO films deposited on PET and glass substrates were not much different; having values 5.1 and 5.3 kΩ/□ and decreased to 3.05, 3.1 kΩ/□ respectively with increasing oxygen partial pressure. The thicknesses of the films on both substrates were ˜700 nm. It was also noted that further increase in oxygen partial pressure caused increase in resistivity due to formation of defects in NiO.

  11. Global Ocean Surface Water Partial Pressure of CO2 Database: Measurements Performed During 1968-2007 (Version 2007)

    SciTech Connect

    Kozyr, Alex

    2008-09-30

    More than 4.1 million measurements of surface water partial pressure of CO2 obtained over the global oceans during 1968-2007 are listed in the Lamont-Doherty Earth Observatory (LDEO) database, which includes open ocean and coastal water measurements. The data assembled include only those measured by equilibrator-CO2 analyzer systems and have been quality-controlled based on the stability of the system performance, the reliability of calibrations for CO2 analysis, and the internal consistency of data. To allow re-examination of the data in the future, a number of measured parameters relevant to pCO2 measurements are listed. The overall uncertainty for the pCO2 values listed is estimated to be ± 2.5 µatm on the average. For simplicity and for ease of reference, this version is referred to as 2007, meaning that data collected through 31 December 2007 has been included. It is our intention to update this database annually. There are 37 new cruise/ship files in this update. In addition, some editing has been performed on existing files so this should be considered a V2007 file. Also we have added a column reporting the partial pressure of CO2 in seawater in units of Pascals. The data presented in this database include the analyses of partial pressure of CO2 (pCO2), sea surface temperature (SST), sea surface salinity (SSS), pressure of the equilibration, and barometric pressure in the outside air from the ship’s observation system. The global pCO2 data set is available free of charge as a numeric data package (NDP) from the Carbon Dioxide Information Analysis Center (CDIAC). The NDP consists of the oceanographic data files and this printed documentation, which describes the procedures and methods used to obtain the data.

  12. 46 CFR 154.1735 - Methyl acetylene-propadiene mixture.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... mixture must have a refrigeration system without vapor compression or have a refrigeration system with the... separate cargo piping, vent piping, and refrigeration equipment for methyl acetylene-propadiene that are segregated from other cargo piping, vent piping and refrigeration equipment on the vessel....

  13. 46 CFR 154.1735 - Methyl acetylene-propadiene mixture.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... mixture must have a refrigeration system without vapor compression or have a refrigeration system with the... separate cargo piping, vent piping, and refrigeration equipment for methyl acetylene-propadiene that are segregated from other cargo piping, vent piping and refrigeration equipment on the vessel....

  14. 46 CFR 154.1735 - Methyl acetylene-propadiene mixture.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... mixture must have a refrigeration system without vapor compression or have a refrigeration system with the... separate cargo piping, vent piping, and refrigeration equipment for methyl acetylene-propadiene that are segregated from other cargo piping, vent piping and refrigeration equipment on the vessel....

  15. Interstitial pneumonitis after acetylene welding: a case report.

    PubMed

    Brvar, Miran

    2014-01-01

    Acetylene is a colorless gas commonly used for welding. It acts mainly as a simple asphyxiant. In this paper, however, we present a patient who developed a severe interstitial pneumonitis after acetylene exposure during aluminum welding. A 44-year old man was welding with acetylene, argon and aluminum electrode sticks in a non-ventilated aluminum tank for 2 h. Four hours after welding dyspnea appeared and 22 h later he was admitted at the Emergency Department due to severe respiratory insufficiency with pO2 = 6.7 kPa. Chest X-ray showed diffuse interstitial infiltration. Pulmonary function and gas diffusion tests revealed a severe restriction (55% of predictive volume) and impaired diffusion capacity (47% of predicted capacity). Toxic interstitial pneumonitis was diagnosed and high-dose systemic corticosteroid methylprednisolone and inhalatory corticosteroid fluticasone therapy was started. Computed Tomography (CT) of the lungs showed a diffuse patchy ground-glass opacity with no signs of small airway disease associated with interstitial pneumonitis. Corticosteroid therapy was continued for the next 8 weeks gradually reducing the doses. The patient's follow-up did not show any deterioration of respiratory function. In conclusion, acetylene welding might result in severe toxic interstitial pneumonitis that improves after an early systemic and inhalatory corticosteroid therapy. PMID:24658888

  16. Fatal carbon monoxide intoxication after acetylene gas welding of pipes.

    PubMed

    Antonsson, Ann-Beth; Christensson, Bengt; Berge, Johan; Sjögren, Bengt

    2013-06-01

    Acetylene gas welding of district heating pipes can result in exposure to high concentrations of carbon monoxide. A fatal case due to intoxication is described. Measurements of carbon monoxide revealed high levels when gas welding a pipe with closed ends. This fatality and these measurements highlight a new hazard, which must be promptly prevented. PMID:23307861

  17. Nitrogen Fixation (Acetylene Reduction) Associated with Duckweed (Lemnaceae) Mats

    PubMed Central

    Zuberer, D. A.

    1982-01-01

    Duckweed (Lemnaceae) mats in Texas and Florida were investigated, using the acetylene reduction assay, to determine whether nitrogen fixation occurred in these floating aquatic macrophyte communities. N2-fixing microorganisms were enumerated by plating or most-probable-number techniques, using appropriate N-free media. Results of the investigations indicated that substantial N2-fixation (C2H2) was associated with duckweed mats in Texas and Florida. Acetylene reduction values ranged from 1 to 18 μmol of C2H4 g (dry weight)−1 day−1 for samples incubated aerobically in light. Dark N2 fixation was always two- to fivefold lower. 3-(3,4-Dichlorophenyl)-1,1-dimethylurea (7 to 10 μM) reduced acetylene reduction to levels intermediate between light and dark incubation. Acetylene reduction was generally greatest for samples incubated anaerobically in the light. It was estimated that 15 to 20% of the N requirement of the duckweed could be supplied through biological nitrogen fixation. N2-fixing heterotrophic bacteria (105 cells g [wet weight]−1 and cyanobacteria (105 propagules g [wet weight]−1 were associated with the duckweed mats. Azotobacter sp. was not detected in these investigations. One diazotrophic isolate was classified as Klebsiella. PMID:16345992

  18. Low energy electron impact vibrational excitation of acetylene

    NASA Astrophysics Data System (ADS)

    Patra, Sigma; Hargreaves, Leigh; Khakoo, Murtadha

    2016-05-01

    Experimental differential cross sections for the vibration excitation of the four fundamental modes of acetylene at low incident electron energies from 1 eV to 20 eV and scattering angles of 10o to 130o will be presented. The results will be compared to results available in the literature. Funded by NSF-AMOP-RUI Grant.

  19. 77 FR 13969 - Revising Standards Referenced in the Acetylene Standard

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-08

    ... Association (GGA) acetylene standard (see 76 FR 75782). In the DFR, OSHA deleted reference to CGA G-1-2003 and... final rule published on December 5, 2011 (76 FR 75782), is effective on March 5, 2012. For the purposes....C. 553, Secretary of Labor's Order 1-2012 (77 FR 3912), and 29 CFR part 1911. Signed at...

  20. 76 FR 75840 - Revising Standards Referenced in the Acetylene Standard

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-05

    ... language from outdated standards published by standards developing organizations (``SDO standards'') (69 FR... Association standard, CGA G-1-2003, in the Acetylene Standard. See 74 FR 40442 and 74 FR 40450, respectively. OSHA received no adverse comments on the DFR, and it became effective on November 9, 2009. See 74...

  1. Near-threshold vibrational excitation of acetylene by positron impact

    SciTech Connect

    Oliveira, Eliane M. de; Lima, Marco A. P.; Sanchez, Sergio d'A.; Varella, Marcio T. do N.

    2010-01-15

    We report vibrational excitation cross sections for C-C and C-H symmetric stretch modes of acetylene by positron impact. The contribution of these infrared inactive modes to the annihilation parameter is also addressed. The Feshbach projection operator approach was employed to vibrationally resolve e{sup +}-acetylene scattering phase shifts obtained with the Schwinger multichannel method. The present results point out a virtual state pole at the equilibrium geometry of acetylene that becomes a bound state as either bond is stretched, in qualitative agreement with previous calculations for small hydrocarbons. The vibrational couplings are stronger for the C-C mode, giving rise to a bound state pole within the Franck-Condon region of the vibrational ground state. These bound and virtual states give rise to sharp threshold structures (vibrational resonances) in both the vibrational excitation cross sections and the annihilation parameter (Z{sub eff}). We found fair agreement between the present calculations and previously reported e{sup +}-acetylene vibrational excitation cross sections.

  2. Phase Transitions and Phase Decomposition of La{1-x}Sr{x}CoO{3-delta} in Low Oxygen Partial Pressures

    SciTech Connect

    Ovenstone,J.; White, J.; Misture, S.

    2008-01-01

    High-temperature X-ray diffraction has been used to investigate the phase stability of lanthanum strontium cobalt oxide (LSC) for a range of materials with the formula La1-xSrxCoO3-{delta} (x = 0.7, 0.4, and 0.2). The stability of LSC increases with La content in low oxygen partial pressures at high temperature. Oxygen vacancy ordering has been observed for all three compositions in either low oxygen pressure or under reducing gas, as evidenced by the formation of the brownmillerite phase. The crystal structure of the vacancy-ordered phase was determined using Rietveld analysis of synchrotron X-ray diffraction data. The decomposition products under low oxygen pressure and in reducing conditions have been identified and characterized, including the phase transition and thermal expansion of the primary decomposition products, LaSrCoO4 and LaSrCoO3.5.

  3. Mass spectrometric determination of partial pressures of ions in the saturated vapor over the NaF-Na3AlF6 system

    NASA Astrophysics Data System (ADS)

    Abramov, S. V.; Chilingarov, N. S.; Borshchevsky, A. Ya; Sidorov, L. N.

    2004-01-01

    Mass spectrometric determination of absolute partial pressures of basic charged species Na2F+ and AlF4- in the saturated vapor over the NaF-Na3AlF6 system (1:1 molar ratio) was carried out in the 974-1090 K temperature range. The ion pressures were 5-8 orders of magnitude lower than the pressures of basic molecular components NaAlF4 and NaF. Particular attention was given to the equality of device sensitivity constants for positive and negative ions. Absolute device calibration was carried out using the measured ion currents Na2F+ and AlF4- and the equilibrium constant of heterolytic dissociation available in the literature.

  4. Potent In Vitro Antifungal Activities of Naturally Occurring Acetylenic Acids▿

    PubMed Central

    Li, Xing-Cong; Jacob, Melissa R.; Khan, Shabana I.; Ashfaq, M. Khalid; Babu, K. Suresh; Agarwal, Ameeta K.; ElSohly, Hala N.; Manly, Susan P.; Clark, Alice M.

    2008-01-01

    Our continuing effort in antifungal natural product discovery has led to the identification of five 6-acetylenic acids with chain lengths from C16 to C20: 6-hexadecynoic acid (compound 1), 6-heptadecynoic acid (compound 2), 6-octadecynoic acid (compound 3), 6-nonadecynoic acid (compound 4), and 6-icosynoic acid (compound 5) from the plant Sommera sabiceoides. Compounds 2 and 5 represent newly isolated fatty acids. The five acetylenic acids were evaluated for their in vitro antifungal activities against Candida albicans, Candida glabrata, Candida krusei, Candida tropicalis, Candida parapsilosis, Cryptococcus neoformans, Aspergillus fumigatus, Aspergillus flavus, Aspergillus niger, Trichophyton mentagrophytes, and Trichophyton rubrum by comparison with the positive control drugs amphotericin B, fluconazole, ketoconazole, caspofungin, terbinafine, and undecylenic acid. The compounds showed various degrees of antifungal activity against the 21 tested strains. Compound 4 was the most active, in particular against the dermatophytes T. mentagrophytes and T. rubrum and the opportunistic pathogens C. albicans and A. fumigatus, with MICs comparable to several control drugs. Inclusion of two commercially available acetylenic acids, 9-octadecynoic acid (compound 6) and 5,8,11,14-eicosatetraynoic acid (compound 7), in the in vitro antifungal testing further demonstrated that the antifungal activities of the acetylenic acids were associated with their chain lengths and positional triple bonds. In vitro toxicity testing against mammalian cell lines indicated that compounds 1 to 5 were not toxic at concentrations up to 32 μM. Furthermore, compounds 3 and 4 did not produce obvious toxic effects in mice at a dose of 34 μmol/kg of body weight when administered intraperitoneally. Taking into account the low in vitro and in vivo toxicities and significant antifungal potencies, these 6-acetylenic acids may be excellent leads for further preclinical studies. PMID:18458131

  5. Role of partial miscibility on pressure buildup due to constant rate injection of CO2 into closed and open brine aquifers

    NASA Astrophysics Data System (ADS)

    Mathias, Simon A.; Gluyas, Jon G.; GonzáLez MartíNez de Miguel, Gerardo J.; Hosseini, Seyyed A.

    2011-12-01

    This work extends an existing analytical solution for pressure buildup because of CO2 injection in brine aquifers by incorporating effects associated with partial miscibility. These include evaporation of water into the CO2 rich phase and dissolution of CO2 into brine and salt precipitation. The resulting equations are closed-form, including the locations of the associated leading and trailing shock fronts. Derivation of the analytical solution involves making a number of simplifying assumptions including: vertical pressure equilibrium, negligible capillary pressure, and constant fluid properties. The analytical solution is compared to results from TOUGH2 and found to accurately approximate the extent of the dry-out zone around the well, the resulting permeability enhancement due to residual brine evaporation, the volumetric saturation of precipitated salt, and the vertically averaged pressure distribution in both space and time for the four scenarios studied. While brine evaporation is found to have a considerable effect on pressure, the effect of CO2 dissolution is found to be small. The resulting equations remain simple to evaluate in spreadsheet software and represent a significant improvement on current methods for estimating pressure-limited CO2 storage capacity.

  6. Resistive switching of Ti/HfO2-based memory devices: impact of the atmosphere and the oxygen partial pressure

    NASA Astrophysics Data System (ADS)

    Bertaud, T.; Sowinska, M.; Walczyk, D.; Walczyk, Ch; Kubotsch, S.; Wenger, Ch; Schroeder, T.

    2012-12-01

    The electrical characteristics of different resistance states (virgin, OFF and ON) of a Ti/HfO2/TiN metal-insulator-metal device for resistance random access memory are investigated under different gas ambient. The influence of the atmosphere, the total pressure and the oxygen concentration during electrical measurements is underlined thanks to retention (I-t) and impedance spectroscopy (Z-f) measurements. The total pressure influences the current levels of the three different resistive states: when the total pressure decreases, the current increases, probably due to an increase of the concentration of oxygen vacancies in the HfO2.

  7. The influence of oxygen partial pressure on material properties of Eu3+-doped Y2O2S thin film deposited by Pulsed Laser Deposition

    NASA Astrophysics Data System (ADS)

    Ali, A. G.; Dejene, B. F.; Swart, H. C.

    2016-01-01

    Eu3+-doping has been of interest to improve the luminescent characteristics of thin-film phosphors. Y2O2S:Eu3+ films have been grown on Si (100) substrates by using a Pulsed Laser Deposition technique. The thin films grown under different oxygen deposition pressure conditions have been characterized using structural and luminescent measurements. The X-ray diffraction patterns showed mixed phases of cubic and hexagonal crystal structures. As the oxygen partial pressure increased, the crystallinity of the films improved. Further increase of the O2 pressure to 140 mtorr reduced the crystallinity of the film. Similarly, both scanning electron microscopy and Atomic Force Microscopy confirmed that an increase in O2 pressure affected the morphology of the films. The average band gap of the films calculated from diffuse reflectance spectra using the Kubelka-Munk function was about 4.75 eV. The photoluminescence measurements indicated red emission of Y2O2S:Eu3+ thin films with the most intense peak appearing at 619 nm, which is assigned to the 5D0-7F2 transition of Eu3+. This most intense peak was totally quenched at higher O2 pressures. This phosphor may be a promising material for applications in the flat panel displays.

  8. In-Situ Partial Pressure Measurements and Visual Observation during Crystal Growth of ZnSe by Seeded Physical Vapor Transport

    NASA Technical Reports Server (NTRS)

    Su, Ching-Hua; Feth, Shari; Lehoczky, Sandor L.

    1999-01-01

    An in-situ monitoring furnace was constructed with side windows to perform partial pressure measurements by optical absorption and visual observation of the growing crystal. A fused silica -rowth ampoule with a 4.5 cm long square tube between the source and the seed was prepared for the optical absorption measurements. A ZnSe crystal was grown by the seeded physical vapor transport (PVT) technique in the horizontal configuration. The growth temperature was 1120 C and the furnace translation rate was 3nmVday. Partial pressures of Se2, P(sub Se2), at three locations along the length of the growth ampoule were measured at 90 min intervals during the growth process. The measured P (sub Se2) were in the range of 2.0 to 6.5 x 10(exp -3) atm. The P(sub Se2) results indicated that the partial pressure profile was inconsistent with the results of the one-dimensional diffusion mass transport model and that the source composition shifted toward Se-rich during the run, i.e. the grown crystal was more Zn-rich than the source. The visual observation showed that the seed crystal first etched back, with greater thermal etching occurring along the edges of the seed crystal. Once the growth started, the crystal crew in a predominately contactless mode and facets were evident during growth. The crystal did not grow symmetrically which is believed to be due to the unintentional asymmetry of the radial thermal profile in the furnace.

  9. An investigation on the effect of high partial pressure of hydrogen on the nanocrystalline structure of silicon carbide thin films prepared by radio-frequency magnetron sputtering.

    PubMed

    Daouahi, Mohsen; Omri, Mourad; Kerm, Abdul Ghani Yousseph; Al-Agel, Faisal Abdulaziz; Rekik, Najeh

    2014-10-22

    The aim of the study reported in this paper is to investigate the role of the high partial pressure of hydrogen introduced during the growth of nanocrystalline silicon carbide thin films (nc-SiC:H). For this purpose, we report the preparation as well as spectroscopic studies of four series of nc-SiC:H obtained by radio-frequency magnetron sputtering at high partial pressure of hydrogen by varying the percentage of H2 in the gas mixture from 70% to 100% at common substrate temperature (TS=500°C). The effects of the dilution on the structural changes and the chemical bonding of the different series have been studied using Fourier transform infrared and Raman spectroscopy. For this range of hydrogen dilution, two groups of films were obtained. The first group is characterized by the dominance of the crystalline phase and the second by a dominance of the amorphous phase. This result confirms the multiphase structure of the grown nc-SiC:H thin films by the coexistence of the SiC network, carbon-like and silicon-like clusters. Furthermore, infrared results show that the SiC bond is the dominant absorption peak and the carbon atom is preferentially bonded to silicon. The maximum value obtained of the crystalline fraction is about 77%, which is relatively important compared to other results obtained by other techniques. In addition, the concentration of CHn bonds was found to be lower than that of SiHn for all series. Raman measurements revealed that the crystallization occurs in all series even at 100% H2 dilution suggesting that high partial pressure of hydrogen favors the formation of silicon nanocrystallites (nc-Si). The absence of both the longitudinal acoustic band and the transverse optical band indicate that the crystalline phase is dominant. PMID:25459700

  10. An investigation on the effect of high partial pressure of hydrogen on the nanocrystalline structure of silicon carbide thin films prepared by radio-frequency magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Daouahi, Mohsen; Omri, Mourad; Kerm, Abdul Ghani Yousseph; Al-Agel, Faisal Abdulaziz; Rekik, Najeh

    2015-02-01

    The aim of the study reported in this paper is to investigate the role of the high partial pressure of hydrogen introduced during the growth of nanocrystalline silicon carbide thin films (nc-SiC:H). For this purpose, we report the preparation as well as spectroscopic studies of four series of nc-SiC:H obtained by radio-frequency magnetron sputtering at high partial pressure of hydrogen by varying the percentage of H2 in the gas mixture from 70% to 100% at common substrate temperature (TS = 500 °C). The effects of the dilution on the structural changes and the chemical bonding of the different series have been studied using Fourier transform infrared and Raman spectroscopy. For this range of hydrogen dilution, two groups of films were obtained. The first group is characterized by the dominance of the crystalline phase and the second by a dominance of the amorphous phase. This result confirms the multiphase structure of the grown nc-SiC:H thin films by the coexistence of the Sisbnd C network, carbon-like and silicon-like clusters. Furthermore, infrared results show that the Sisbnd C bond is the dominant absorption peak and the carbon atom is preferentially bonded to silicon. The maximum value obtained of the crystalline fraction is about 77%, which is relatively important compared to other results obtained by other techniques. In addition, the concentration of CHn bonds was found to be lower than that of SiHn for all series. Raman measurements revealed that the crystallization occurs in all series even at 100% H2 dilution suggesting that high partial pressure of hydrogen favors the formation of silicon nanocrystallites (nc-Si). The absence of both the longitudinal acoustic band and the transverse optical band indicate that the crystalline phase is dominant.

  11. Plant and environment interactions: Growth and yield response of commercial bearing-age {open_quote}Casselman{close_quote} plum trees to various ozone partial pressures

    SciTech Connect

    Retzlaff, W.A.; Williams, L.E.; DeJong, T.M.

    1997-05-01

    Nursery stock of plum (Prunus salicina Lindel., cv. Casselman) was planted 1 Apr. 1988 in an experimental orchard at the Univ. of California Kearney Agricultural Center near Fresno, CA. Trees in this study were enclosed in open-top fumigation chambers on 1 May 1989, and exposed to three atmospheric ozone partial pressures (charcoal filtered air, ambient air, and ambient air + ozone) during the 1989 through 1992 growing seasons (typically 1 Apr. - 1 Nov.). A nonchamber treatment plot was used to assess chamber effects on tree performance. This study details the results of the exposures during the initial commercial bearing period (1991 through 1993) in this orchard. The mean 12-h (0800-2000 h Pacific Daylight Time [PDT]) ozone partial pressures during the experimental periods in the charcoal filtered, ambient, ambient + ozone, and nonchamber treatments averaged 0.031, 0.048, 0.091, and 0.056 {mu}Pa Pa{sup {minus}1} in 1991 and 1992, respectively. Fruit number per tree decreased as atmospheric ozone partial pressure increased from the charcoal filtered to ambient + ozone treatment, significantly affecting yield. Yield of plum trees averaged 23.6, 19.8, 13.7, and 17.9 kg tree{sup {minus}1} in 1991 and 1992 in the charcoal filtered, ambient, ambient + ozone, and nonchamber treatments, respectively. Only one out of the five original treatment plots was exposed to ozone treatments during the 1993 growing season. Yield of plum trees in this single replicate in 1993 was reduced by increased atmospheric ozone partial pressure. Yield of plum trees in the four remaining unexposed treatment plots in 1993 was 16.7, 17.9, and 16.0 kg tree{sup {minus}1} in the previous charcoal filtered, ambient, and ambient + ozone treatments respectively. The similarity in yield of the post-chamber treatments indicates that a change in air quality in the current growing season can affect yield of Casselman plum trees. 26 refs., 6 figs., 4 tabs.

  12. EPR study of the effect of partial pressure of oxygen in the growth atmosphere on concentration of chromium centers in synthetic forsterite

    NASA Astrophysics Data System (ADS)

    Akhmetzyanov, D. A.; Dudnikova, V. B.; Zharikov, E. V.; Zhiteitsev, E. R.; Zaitseva, O. N.; Konovalov, A. A.; Tarasov, V. F.

    2013-03-01

    Samples of synthetic forsterite doped with chromium and grown in an argon atmosphere with different oxygen concentrations (at a partial pressure of oxygen in the range from 0.03 to 0.78 kPa) have been studied using multifrequency electron paramagnetic resonance (EPR) spectroscopy. It has been demonstrated how the oxidizing properties of the atmosphere during the growth of crystals affect the relative concentration of di-, tri-, and tetravalent chromium ions in the samples. The structure of trivalent chromium impurity centers has been discussed.

  13. Enhanced acetylene emission near the north pole of Jupiter

    NASA Technical Reports Server (NTRS)

    Drossart, Pierre; Bezard, Bruno; Encrenaz, Therese; Atreya, Sushil; Lacy, John; Serabyn, Eugene; Tokunaga, Alan

    1986-01-01

    The present paper is concerned with observations of acetylene fundamental and hot band vibrational emission lines from the planet Jupiter. It is pointed out that the observation of a polar bright spot in the atmosphere of Jupiter is characterized by an enhancement in the individual lines of C2H2 which can be interpreted as an enhancement in the acetylene abundance. However, a purely thermal effect, on non-LTE phenomena cannot be excluded. The intensity of the observed hot band lines is also consistent with either hypothesis. The reported observations were performed with a cooled Fabry-Perot Grating Spectrometer (FPGS). Observations and instrumentation are considered in detail along with the calculation of synthetic spectra on the basis of a line-by-line computation, and the interpretation of the obtained data.

  14. Enhanced acetylene emission near the north pole of Jupiter

    NASA Technical Reports Server (NTRS)

    Drossart, P.; Bezard, B.; Atreya, S.; Lacy, J.; Serabyn, E.

    1986-01-01

    The present paper is concerned with observations of acetylene fundamental and hot band vibrational emission lines from the planet Jupiter. It is pointed out that the observation of a polar bright spot in the atmosphere of Jupiter is characterized by an enhancement in the individual lines of C2H2 which can be interpreted as an enhancement in the acetylene abundance. However, a purely thermal effect, or non-LTE phenomena cannot be excluded. The intensity of the observed hot band lines is also consistent with either hypothesis. The reported observations were performed with a cooled Fabry-Perot Grating Spectrometer (FPGS). Observations and instrumentation are considered in detail along with the calculation of synthetic spectra on the basis of a line-by-line computation, and the interpretation of the obtained data.

  15. Geochemical signatures of metasedimentary rocks of high-pressure granulite facies and their relation with partial melting: Carvalhos Klippe, Southern Brasília Belt, Brazil

    NASA Astrophysics Data System (ADS)

    Cioffi, Caue Rodrigues; Campos Neto, Mario da Costa; da Rocha, Brenda Chung; Moraes, Renato; Henrique-Pinto, Renato

    2012-12-01

    High-grade metasedimentary rocks can preserve geochemical signatures of their sedimentary protolith if significant melt extraction did not occur. Retrograde reaction textures provide the main evidence for trapped melt in the rock fabrics. Carvalhos Klippe rocks in Southern Brasília Orogen, Brazil, present a typical high-pressure granulite assemblage with evidence of mica breakdown partial melting (Ky + Grt + Kfs ± Bt ± Rt). The metamorphic peak temperatures obtained by Zr-in-Rt and ternary feldspar geothermometers are between 850 °C and 900 °C. The GASP baric peak pressure obtained using grossular rich garnet core is 16 kbar. Retrograde reaction textures in which the garnet crystals are partially to totally replaced by Bt + Qtz ± Fsp intergrowths are very common in the Carvalhos Klippe rocks. These reactions are interpreted as a result of interactions between residual phases and trapped melt during the retrograde path. In the present study the geochemical signatures of three groups of Carvalhos Klippe metasedimentary rocks are analysed. Despite the high metamorphic grade these three groups show well-defined geochemical features and their REE patterns are similar to average compositions of post-Archean sedimentary rocks (PAAS, NASC). The high-pressure granulite facies Grt-Bt-Pl gneisses with immature arenite (wacke, arkose or lithic-arenite) geochemical signatures present in the Carvalhos Klippe are compared to similar rocks in amphibolite facies from the same tectonic framework (Andrelândia Nappe System). The similar geochemical signatures between Grt-Bt-Pl gneisses metamorphosed in high-pressure granulite facies and Grt-Bt-Pl-Qtz schists from the Andrelândia and Liberdade Nappes, with minimal to absent melting conditions, are suggestive of low rates of melt extraction in these high-grade rocks. The rocks with pelitic compositions most likely had higher melt extraction and even under such circumstances nevertheless tend to show REE patterns similar to

  16. Orbital-resolved strong-field single ionization of acetylene

    NASA Astrophysics Data System (ADS)

    Ji, Qinying; Cui, Sen; You, Xinyuan; Gong, Xiaochun; Song, Qiying; Lin, Kang; Pan, Haifeng; Ding, Jingxin; Zeng, Heping; He, Feng; Wu, Jian

    2015-10-01

    We resolve the strong-field single ionization of acetylene into different channels by differentially normalizing the lateral momenta of the directly escaped electrons from the aligned and antialigned molecules. Distinct electron momentum distributions for different channels are observed using both near-infrared and ultraviolet femtosecond laser pulses with Keldysh parameters close to 1. The results are interpreted as a signature of multiple ionization orbitals.

  17. Aquatic acetylene-reduction techniques: solutions to several problems.

    PubMed

    Flett, R J; Hamilton, R D; Campbell, N E

    1976-01-01

    Previous methods of performing aquatic acetylene-reduction assays are described and several problems associated with them are discussed. A refinement of these older techniques is introduced and problems that it overcomes are also discussed. A depth profile of nitrogen fixation (C2H4 production), obtained by the refined technique, is shown for a fertilized Canadian Shield lake in the Experimental Lakes Area of northwestern Ontario. PMID:814983

  18. Tuning the Electronic Properties of Acetylenic Fluorenes by Phosphaalkene Incorporation.

    PubMed

    Svyaschenko, Yurii V; Orthaber, Andreas; Ott, Sascha

    2016-03-14

    Versatile synthetic protocols for 2,7- and 3,6-diacetylenic fluorene-9-ylidene phosphanes (F9Ps) were developed. Protodesilylation of trimethylsilyl-protected acetylenic F9Ps affords terminal acetylenes that can be employed in Sonogashira and Glaser-type C-C coupling reactions to give thienyl-decorated and butadiyne-bridged fluorene-9-ylidene phosphanes, respectively. As evidenced by UV/Vis spectroscopy and cyclic voltammetry and corroborated by ab initio calculations, the presence of the P center in the F9Ps induces a significantly reduced HOMO-LUMO splitting that originates from stabilization of the LUMO levels. Variation of the acetylene substitution pattern is an additional tool to influence the optical and electronic properties. Whereas 3,6-disubstituted F9Ps have strong absorptions around 400 nm, mainly due to π-π* transitions, 2,7-diacetylenic F9Ps exhibit longest-wavelength absorptions that have significant charge-transfer character with an onset around 520 nm. PMID:26833389

  19. Dubinin-Astakhov model for acetylene adsorption on metal-organic frameworks

    NASA Astrophysics Data System (ADS)

    Cheng, Peifu; Hu, Yun Hang

    2016-07-01

    Acetylene (C2H2) is explosive at a pressure above 29 psi, causing a safety issue for its storage and applications. C2H2 adsorption on metal-organic frameworks (MOFs) has been explored to solve the issue. However, a suitable isotherm equation for C2H2 adsorption on various MOFs has not been found. In this paper, it was demonstrated that Dubinin-Astakhov equation can be exploited as a general isotherm model to depict C2H2 adsorption on MOF-5, ZIF-8, HKUST-1, and MIL-53. In contrast, commonly used Langmuir and BET models exhibited their inapplicability for C2H2 adsorption on those MOFs.

  20. Analysis of the Pressure Rise in a Partially Filled Liquid Tank in Microgravity with Low Wall Heat Flux and Simultaneous Boiling and Condensation

    NASA Technical Reports Server (NTRS)

    Hasan, Mohammad M.; Balasubramaniam, R.

    2012-01-01

    Experiments performed with Freon 113 in the space shuttle have shown that in a pro- cess of very slow heating, high liquid superheats can be sustained for a long period in microgravity. In a closed system explosive vaporization of superheated liquid resulted in pressure spikes of varying magnitudes. In this paper, we analyze the pressure rise in a partially lled closed tank in which a large vapor bubble (i.e., ullage) is initially present, and the liquid is subjected to a low wall heat ux. The liquid layer adjacent to the wall becomes superheated until the temperature for nucleation of the bubbles (or the incipience of boiling) is achieved. In the absence of the gravity-induced convection large quantities of superheated liquid can accumulate over time near the heated surface. Once the incipience temperature is attained, explosive boiling occurs and the vapor bubbles that are produced on the heater surface tend to quickly raise the tank pressure. The liquid-vapor saturation temperature increases as well. These two e ects tend to induce condensation of the large ullage bubble that is initially present, and tends to mitigate the tank pressure rise. As a result, the tank pressure is predicted to rise sharply, attain a maximum, and subsequently decay slowly. The predicted pressure rise is compared with experimental results obtained in the microgravity environments of the space shuttle for Freon 113. The analysis is appli- cable, in general to heating of liquid in closed containers in microgravity and to cryogenic fuel tanks, in particular where small heat leaks into the tank are unavoidable.

  1. Morphology and gas sensing characteristics of density-controlled CuO nanostructures obtained by varying the oxygen partial pressure during growth

    NASA Astrophysics Data System (ADS)

    Lee, Dongjin; Jin, Changhyun; Noh, Youngwook; Park, Seokhyun; Choi, Sun-Woo

    2016-07-01

    By exerting different O2 partial pressures (0, 20, 40, and 60 sccm) onto copper substrates, we discovered that the growth parameter, namely, the O2 flow rate, affects the degree of nucleation, diameter, length, and crystalline quality of CuO nanowires (NWs). Scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM) were used to analyze the evolution of the morphological and the microstructural changes in the CuO nanostructures. The formation of a Cu2O interlayer between the Cu and the CuO layers could be adjusted by controlling more precisely the O2 flow rate. In addition, the reducing (H2S) and the oxidizing (O2, NO2, and SO2) gas sensing performances of these O2-assisted CuO NWs were compared with those of CuO NWs grown in static air. The response to the reducing H2S of the sensors based on CuO NWs grown using O2 at 40 sccm showed a higher electrical change and faster response and recovery times than the sensors based on CuO NWs grown using lower O2 flow rates, including the ones grown in static air and/or used for sensing oxidizing gases (O2, NO2, and SO2) did. On the basis of their growth and their gas-sensing applications, the possible mechanisms characteristic of the density-controlled CuO NWs grown using various O2 partial pressures are discussed.

  2. Effects of Pleistocene, pre-industrial, current, and future CO[sub 2] partial pressures on C[sub 3] and C[sub 4] plant growth

    SciTech Connect

    Dippery, J.K.; Strain, B.R. )

    1993-06-01

    To study plant growth in atmospheric CO[sub 2] concentrations ranging from Pleistocene through predicted future levels, Amaranthus retroflexus (C[sub 4]) and Abutilon theophrasti (C[sub 3]) were grown in growth chambers at four CO[sub 2] levels (15 Pa, Pleistocene minimum; 27 Pa, pre-industrial; 35 Pa, current; 70 Pa, future). Thirty-five days after emergence, shoot dry weight, root dry weight and leaf area did not differ between any CO[sub 2] levels for the C[sub 4] species. The C[sub 3] species showed increased root and shoot dry weights and leaf areas when grown in CO[sub 2] partial pressures of 15 Pa, 27 Pa and 35 Pa. This evidence indicates that plant growth in C[sub 4] species is unaffected by atmospheric CO[sub 2] levels ranging from the Pleistocene minimum through the future; whereas, C[sub 3] species show growth increases as CO[sub 2] partial pressures rise above the Pleistocene minimum.

  3. Influence of Oxygen Partial Pressure on Opto-Electrical Properties, Crystallite Size and Dislocation Density of Sn Doped In_2 O_3 Nanostructures

    NASA Astrophysics Data System (ADS)

    Soleimanian, Vishtasb; Ghasemi Varnamkhasti, Mohsen

    2016-06-01

    In this research, high-quality Sn doped indium oxide (ITO) thin films were grown on glass slide substrates using an electron beam evaporation method. Vacuum chamber partial pressure was changed and the electro-optical as well as the microstructure parameters were investigated. The microstructure of prepared films was evaluated by x-ray diffraction analysis in terms of crystallite size and dislocation density. It was found that the best results [high transparency (88%) over the visible wavelength region, low sheet resistance of 12.8 Ω /square, the optical band gap of 3.76 eV, crystallite size of 49.5 nm and dislocation density of 1.42 × 10^{14} m^{-2} ] were achieved for the sample produced at a partial pressure of 1 × 10^{-4} mbar. Therefore, one can successfully control the physical properties of ITO films by varying the oxygen content of the evaporation system. The correlation between the band gap and carrier concentration in addition to the average crystallite size of films was also established.

  4. The effect of the partial pressure of water vapor on the surface tension of the liquid water-air interface.

    PubMed

    Pérez-Díaz, José L; Álvarez-Valenzuela, Marco A; García-Prada, Juan C

    2012-09-01

    Precise measurements of the surface tension of water in air vs. humidity at 5, 10, 15, and 20 °C are shown. For constant temperature, surface tension decreases linearly for increasing humidity in air. These experimental data are in good agreement with a simple model based on Newton's laws here proposed. It is assumed that evaporating molecules of water are ejected from liquid to gas with a mean normal component of the speed of "ejection" greater than zero. A high humidity in the air reduces the net flow of evaporating water molecules lowering the effective surface tension on the drop. Therefore, just steam in air acts as an effective surfactant for the water-air interface. It can partially substitute chemical surfactants helping to reduce their environmental impact. PMID:22717083

  5. Acetylene is an active-site-directed, slow-binding, reversible inhibitor of Azotobacter vinelandii hydrogenase

    SciTech Connect

    Hyman, M.R.; Arp, D.J.

    1987-10-06

    The inhibition of purified and membrane-bound hydrogenase from Azotobacter vinelandii by dihydrogen-free acetylene was investigated. The inhibition was a time-dependent process which exhibited first-order kinetics. Both H/sub 2/ and CO protected against the inhibition by acetylene. K/sub protect(app)/ values of 0.41 and 24 ..mu..M were derived for these gases, respectively. Both H/sub 2/-oxidizing activity and the tritium exchange capacity of the purified enzyme were inhibited at the same rate by acetylene. Removal of acetylene reversed the inhibition for both the purified and the membrane-associated form of the enzyme. The purified hydrogenases from both Rhizobium japonicum and Alcaligenes eutrophus H16 were also inhibited by acetylene in a time-dependent fashion. These findings suggest that acetylene is an active-site-directed, slow-binding, reversible inhibitor of some membrane-bound hydrogenases from aerobic bacteria.

  6. Pressure-distribution measurements on a rectangular wing with a partial-span split flap in curved flight

    NASA Technical Reports Server (NTRS)

    Rokus, Frank G

    1939-01-01

    Pressure-distribution tests were made on the 32-foot whirling arm of the Daniel Guggenheim Airship Institute of a rectangular wing of NACA 23012 section to determine the rolling and the yawing moment due to angular velocity in yaw. The model was tested at 0 and 5 degree pitch; 0, +/- 5, and +/- 10 degrees yaw; and with no flap and with split flaps 25, 50 and 75 percent of the wing span and deflected 60 degrees. The results are given in the form of span load distributions and as calculated moment coefficients. The experimental values of rolling- and yawing-moment coefficients were in fairly close agreement with theory.

  7. Pressure-distribution measurements on a tapered wing with a partial-span split flap in curved flight

    NASA Technical Reports Server (NTRS)

    Troller, TH; Rokus, F

    1939-01-01

    Pressure-distribution tests were made on the 32-foot whirling arm of the Daniel Guggenheim Airship Institute of a tapered wing to determine the rolling and the yawing moments due to an angular velocity in yaw. The model was tested at 0 degree and 5 degree pitch; 0 degree, 5 degree, and 10 degree yaw; and with split flaps covering 25, 50, 75, and 100 percent of the wing span and deflected 60 degrees. The results are given in the form of load distributions and as calculated moment coefficients. The experimental values of rolling- and yawing- moment coefficients were in fairly close agreement with theory.

  8. Influence of CH(4) partial pressure on the microstructure of sputter-deposited tungsten carbide thin films.

    PubMed

    Abdelouahdi, K; Sant, C; Miserque, F; Aubert, P; Zheng, Y; Legrand-Buscema, C; Perrière, J

    2006-02-15

    Tungsten carbide thin films have been prepared by reactive rf sputtering from a tungsten target in various Ar-CH(4) mixtures. The composition, structure, microstructure and chemical state of the films have been investigated by the complementary use of RBS, NRA, XRD, GIXRD, TEM and XPS analyses. These characteristics of the films were then correlated to their mechanical properties determined by hardness (H), Young's modulus (E(r)) and friction coefficient measurements. Under low CH(4) pressures, the formation of a mixture of nanocrystalline WC(1-x) and W(2)C phases has been observed. A pure WC(1-x) phase was observed in films having a composition close to W(1)C(0.9). With increasing CH(4) pressure, the amount of carbon in the films increases, leading to a progressive amorphization of tungsten carbide deposited layers. Nanocomposite films appeared to be formed, with WC(1-x) nanograins (<3 nm) dispersed in an amorphous carbon matrix. The film deposited at 30% of CH(4) exhibits a-C:H phase. The nature of the phases present in the films plays an important role on their mechanical properties, as shown by the wide domain of variation of the films' hardness (between 22 and 5.5 GPa) and the plastic deformation parameter H(3)/E(r)(2) (between 0.08 and 0.04). PMID:21697565

  9. Experimental investigation of the electrical behavior of olivine during partial melting under pressure and application to the lunar mantle

    NASA Astrophysics Data System (ADS)

    Pommier, A.; Leinenweber, K.; Tasaka, M.

    2015-09-01

    Electrical conductivity measurements were performed during melting experiments of olivine compacts (dry and hydrous Fo77 and Fo90) at 4 and 6 GPa in order to investigate melt transport properties and quantify the effect of partial melting on electrical properties. Experiments were performed in the multi-anvil apparatus and electrical measurements were conducted using the impedance spectroscopy technique with the two-electrode method. Changes in impedance spectra were used to identify the transition from an electrical response controlled by the solid matrix to an electrical response controlled by the melt phase. This transition occurs slightly above the solidus temperature and lasts until Tsolidus + 75 °C (±25). At higher temperature, a significant increase in conductivity (corresponding to an increase in conductivity values by a factor ranging from ∼30 to 100) is observed, consistent with the transition from a tube-dominated network to a structure in which melt films and pools become prominent features. This increase in conductivity corresponds to an abrupt jump for all dry samples and to a smoother increase for the hydrous sample. It is followed by a plateau at higher temperature, suggesting that the electrical response of the investigated samples lacks sensitivity to temperature at an advanced stage of partial melting. Electron microprobe analyses on quenched products indicated an increase in Mg# (molar Mg / (Mg +Fe)) of olivine during experiments (∼77-93 in the quenched samples with an initial Fo77 composition and ∼92-97 in the quenched samples with an initial Fo90 composition) due to the partitioning of iron to the melt phase. Assuming a respective melt fraction of 0.10 and 0.20 before and after the phase of significant increase in conductivity, in agreement with previous electrical and permeability studies, our results can be reproduced satisfactorily by two-phase electrical models (the Hashin and Shtrikman bounds and the modified brick layer model

  10. Acetylene-derived polymers and their applications in hair and skin care.

    PubMed

    Petter, P J

    1989-02-01

    Synopsis Since the introduction over 30 years ago of polyvinylpyrrolidone (PVP) as the first synthetic hairspray resin, acetylene-derived polymers have found wide and increasing applications in the cosmetics and toiletries industry. This review covers the two main classes of acetylenic polymers. In the first class, in which the chemistry may be traced back to reaction of acetylene with formaldehyde, are included PVP homopolymers and copolymers of VP with vinyl acetate, dimethylaminoethyl methacrylate, vinylcaprolactam and styrene. In the second class, stemming from reaction of acetylene with methanol, are the poly (vinyl methyl ether/maleic acid) monoester resins. PMID:19456933

  11. Fluid resuscitation guided by sublingual partial pressure of carbon dioxide during hemorrhagic shock in a porcine model.

    PubMed

    Xu, Jiefeng; Ma, Linhao; Sun, Shijie; Lu, Xiaoye; Wu, Xiaobo; Li, Zilong; Tang, Wanchun

    2013-04-01

    To avoid aggressive fluid resuscitation during hemorrhagic shock, fluid resuscitation is best guided by a specific measurement of tissue perfusion. We investigated whether fluid resuscitation guided by sublingual PCO2 would reduce the amount of resuscitation fluid without compromising the outcomes of hemorrhagic shock. Ten male domestic pigs weighing between 34 and 37 kg were used. Forty-five percent of estimated blood volume was removed during an interval of 1 h. The animals were then randomized to receive fluid resuscitation based on either sublingual PCO2 or blood pressure (BP). In the sublingual PCO2-guided group, resuscitation was initiated when sublingual PCO2 exceeded 70 Torr and stopped when it decreased to 50 Torr. In the BP-guided group, resuscitation was initiated when mean aortic pressure decreased to 60 mmHg and stopped when it increased to 90 mmHg. First, Ringer's lactate solution (RLS) of 30 mL kg was administered; subsequently, the shed blood was transfused if sublingual PCO2 remained greater than 50 Torr in the sublingual PCO2-guided group or mean aortic pressure was less than 90 mmHg in the BP-guided group. All the animals were monitored for 4 h and observed for an additional 68 h. In the sublingual PCO2-guided group, fluid resuscitation was required in only 40% of the animals. In addition, a significantly lower volume of RLS (170 ± 239 mL, P = 0.005 vs. BP-guided group) was administered without the need for blood infusion in this group. However, in the BP-guided group, all the animals required a significantly larger volume of fluid (955 ± 381 mL), including both RLS and blood. There were no differences in postresuscitation tissue microcirculation, myocardial and neurologic function, and 72-h survival between groups. During hemorrhagic shock, fluid resuscitation guided by sublingual PCO2 significantly reduced the amount of resuscitation fluid without compromising the outcomes of hemorrhagic shock. PMID:23364438

  12. Techniques for Elastic Properties Measurements of Partial Molten Rocks, Hydrous Minerals and Melts in Gas Pressure Vessels and Multi-Anvil Devices

    NASA Astrophysics Data System (ADS)

    Mueller, H. J.; Roetzler, K.; Schilling, F. R.; Wehber, M.; Lathe, C.

    2008-12-01

    The interpretation of highly resolved seismic data from Earth's deep interior require measurements of the physical properties of Earth materials under experimental simulated mantle conditions. For deep crustal to uppermost mantle conditions high performance gas pressure vessels enable a virtually unrestricted optimization of the measuring configurations for high p-T-conditions [1]. Exhumed high pressure rocks can be used as representative samples. The paper presents transient measurements of elastic wave velocities for granulite facies rocks under partial melting conditions. Despite the compact natural rock samples as a result of long-term experiments exceeding pressures of 1.5 GPa and temperatures of 1,000°C newly-formed garnets, orthopyroxenes and potash feldspars could be found in the samples after the experiments. Discovering the huge water storage capacity of nominally anhydrous minerals (NAMs) under high pressure conditions dramatically changed our image of state and dynamics of Earth's deep interior [2]. The simulation of these in situ conditions require using of diamond anvil cells (DAC) and multi-anvil devices (MAD) as well as mostly synthetical samples. MADs are more limited in pressure, but provide sample volumes 3 to 7 orders of magnitude bigger. They offer small and even adjustable temperature gradients over the whole sample. The bigger samples make anisotropy and structural effects in complex systems accessible for measurements in principle. Using ultrasonic interferometry the measurement of both elastic wave velocities have no limits for opaque and encapsulated samples. Using the 6 to 8 anvils of a MAD as buffers allow the simultaneous recording of acoustic emissions from different directions of space and consequently the localization of the spikes during ongoing phase transitions and dehydration. The recent development of deformation-DIA MADs (D-DIA) make not only deformation measurements under simulated mantle conditions possible, but also the

  13. Efficacy of nitric oxide, with or without continuing antihypertensive treatment, for management of high blood pressure in acute stroke (ENOS): a partial-factorial randomised controlled trial

    PubMed Central

    2015-01-01

    Summary Background High blood pressure is associated with poor outcome after stroke. Whether blood pressure should be lowered early after stroke, and whether to continue or temporarily withdraw existing antihypertensive drugs, is not known. We assessed outcomes after stroke in patients given drugs to lower their blood pressure. Methods In our multicentre, partial-factorial trial, we randomly assigned patients admitted to hospital with an acute ischaemic or haemorrhagic stroke and raised systolic blood pressure (systolic 140–220 mm Hg) to 7 days of transdermal glyceryl trinitrate (5 mg per day), started within 48 h of stroke onset, or to no glyceryl trinitrate (control group). A subset of patients who were taking antihypertensive drugs before their stroke were also randomly assigned to continue or stop taking these drugs. The primary outcome was function, assessed with the modified Rankin Scale at 90 days by observers masked to treatment assignment. This study is registered, number ISRCTN99414122. Findings Between July 20, 2001, and Oct 14, 2013, we enrolled 4011 patients. Mean blood pressure was 167 (SD 19) mm Hg/90 (13) mm Hg at baseline (median 26 h [16–37] after stroke onset), and was significantly reduced on day 1 in 2000 patients allocated to glyceryl trinitrate compared with 2011 controls (difference −7·0 [95% CI −8·5 to −5·6] mm Hg/–3·5 [–4·4 to −2·6] mm Hg; both p<0·0001), and on day 7 in 1053 patients allocated to continue antihypertensive drugs compared with 1044 patients randomised to stop them (difference −9·5 [95% CI −11·8 to −7·2] mm Hg/–5·0 [–6·4 to −3·7] mm Hg; both p<0·0001). Functional outcome at day 90 did not differ in either treatment comparison—the adjusted common odds ratio (OR) for worse outcome with glyceryl trinitrate versus no glyceryl trinitrate was 1·01 (95% CI 0·91–1·13; p=0·83), and with continue versus stop antihypertensive drugs OR was 1·05 (0·90–1·22; p=0·55). Interpretation

  14. Adenoviral gene transfer of endothelial nitric-oxide synthase (eNOS) partially restores normal pulmonary arterial pressure in eNOS-deficient mice

    PubMed Central

    Champion, Hunter C.; Bivalacqua, Trinity J.; Greenberg, Stanley S.; Giles, Thomas D.; Hyman, Albert L.; Kadowitz, Philip J.

    2002-01-01

    It has been shown that mice deficient in the gene coding for endothelial nitric-oxide synthase (eNOS) have increased pulmonary arterial pressure and pulmonary vascular resistance. In the present study, the effect of transfer to the lung of an adenoviral vector encoding the eNOS gene (AdCMVeNOS) on pulmonary arterial pressure and pulmonary vascular resistance was investigated in eNOS-deficient mice. One day after intratracheal administration of AdCMVeNOS to eNOS−/− mice, there was an increase in eNOS protein, cGMP levels, and calcium-dependent conversion of l-arginine to l-citrulline in the lung. The increase in eNOS protein and activity in eNOS−/− mice was associated with a reduction in mean pulmonary arterial pressure and pulmonary vascular resistance when compared with values in eNOS-deficient mice treated with vehicle or a control adenoviral vector coding for β-galactosidase, AdCMVβgal. These data suggest that in vivo gene transfer of eNOS to the lung in eNOS−/− mice can increase eNOS staining, eNOS protein, calcium-dependent NOS activity, and cGMP levels and partially restore pulmonary arterial pressure and pulmonary vascular resistance to near levels measured in eNOS+/+ mice. Thus, the major finding in this study is that in vivo gene transfer of eNOS to the lung in large part corrects a genetic deficiency resulting from eNOS deletion and may be a useful therapeutic intervention for the treatment of pulmonary hypertensive disorders in which eNOS activity is reduced. PMID:12237402

  15. Acetylene hydratase: a non-redox enzyme with tungsten and iron-sulfur centers at the active site.

    PubMed

    Kroneck, Peter M H

    2016-03-01

    In living systems, tungsten is exclusively found in microbial enzymes coordinated by the pyranopterin cofactor, with additional metal coordination provided by oxygen and/or sulfur, and/or selenium atoms in diverse arrangements. Prominent examples are formate dehydrogenase, formylmethanofuran dehydrogenase, and aldehyde oxidoreductase all of which catalyze redox reactions. The bacterial enzyme acetylene hydratase (AH) stands out of its class as it catalyzes the conversion of acetylene to acetaldehyde, clearly a non-redox reaction and a reaction distinct from the reduction of acetylene to ethylene by nitrogenase. AH harbors two pyranopterins bound to W, and a [4Fe-4S] cluster. W is coordinated by four dithiolene sulfur atoms, one cysteine sulfur, and one oxygen ligand. AH activity requires a strong reductant suggesting W(IV) as the active oxidation state. Two different types of reaction pathways have been proposed. The 1.26 Å structure reveals a water molecule coordinated to W which could gain a partially positive net charge by the adjacent protonated Asp-13, enabling a direct attack of C2H2. To access the W-Asp site, a substrate channel was evolved distant from where it is found in other members of the DMSOR family. Computational studies of this second shell mechanism led to unrealistically high energy barriers, and alternative pathways were proposed where C2H2 binds directly to W. The architecture of the catalytic cavity, the specificity for C2H2 and the results from site-directed mutagenesis do not support this first shell mechanism. More investigations including structural information on the binding of C2H2 are needed to present a conclusive answer. PMID:26790879

  16. The influence of hydrogen sulfide-to-hydrogen partial pressure ratio on the sulfidization of Pd and 70 mol% Pd–Cu membranes

    SciTech Connect

    Iyoha, O.; Enick, R.M.; Killmeyer, R.P.; Morreale, B.

    2007-11-15

    The influence of H2S-to-H2 partial pressure ratio on the sulfidization of Pd and 70 mol% Pd–Cu membrane alloys was studied using various H2Scontaining gas mixtures. The Pd membranes exposed to various H2S mixtures were in very good agreement with the thermodynamic calculations used in this study, resisting sulfidization when exposed to H2S-to-H2 ratios below the equilibrium value predicted for Pd4S formation, and experiencing sulfidization when exposed to ratios above the equilibrium values. The 70 mol% Pd–Cu membranes, however, exhibited deviations from the predicted values, resisting sulfidization at some conditions close to the equilibrium values at which sulfidization was expected, and experiencing sulfidization at some conditions at which resistance was expected. This phenomenon was attributed to deviations of the Pd–Cu alloy from ideality, probably due to Cu segregation at the membrane surface.

  17. The influence of hydrogen sulfide-to-hydrogen partial pressure ratio on the sulfidization of Pd and 70 mol% Pd-Cu membranes

    SciTech Connect

    Iyoha, O.; Enick, R.M.; Killmeyer, R.P.; Morreale, B.D.

    2007-11-15

    The influence of H2S-to-H2 partial pressure ratio on the sulfidization of Pd and 70 mol% Pd–Cu membrane alloys was studied using various H2S-containing gas mixtures. The Pd membranes exposed to various H2S mixtures were in very good agreement with the thermodynamic calculations used in this study, resisting sulfidization when exposed to H2S-to-H2 ratios below the equilibrium value predicted for Pd4S formation, and experiencing sulfidization when exposed to ratios above the equilibrium values. The 70 mol% Pd–Cu membranes, however, exhibited deviations from the predicted values, resisting sulfidization at some conditions close to the equilibrium values at which sulfidization was expected, and experiencing sulfidization at some conditions at which resistance was expected. This phenomenon was attributed to deviations of the Pd–Cu alloy from ideality, probably due to Cu segregation at the membrane surface.

  18. Adaptation of an electrochemical system for measurement and regulation of oxygen partial pressure to a symmetrical thermogravimetric analysis system developed using a Cahn 1000 electrobalance

    NASA Astrophysics Data System (ADS)

    Caneiro, A.; Bavdaz, P.; Fouletier, J.; Abriata, J. P.

    1982-07-01

    We report equipment consisting of the coupling of an electrochemical system for measurement and regulation of oxygen partial pressure (PO2) to a symmetrical thermogravimetric analysis system built on the basis of a Cahn 1000 electrobalance. The electrochemical system allows the measurement and regulation of PO2 within a few percent, and has the additional advantage that it can be checked against systematic errors in an absolute way by means of the ''Faraday's law test.'' The performance of the whole experimental setup is demonstrated by the resolution of a narrow hysteresis loop shown by PO2 as a function of composition in the U3O8 phase of the uranium-oxygen system.

  19. Cantilever stress measurements for pulsed laser deposition of perovskite oxides at 1000 K in an oxygen partial pressure of 10{sup −4} millibars

    SciTech Connect

    Premper, J.; Sander, D.; Kirschner, J.

    2015-03-15

    An in situ stress measurement setup using an optical 2-beam curvature technique is described which is compatible with the stringent growth conditions of pulsed laser deposition (PLD) of perovskite oxides, which involves high substrate temperatures of 1000 K and oxygen partial pressures of up to 1 × 10{sup −4} millibars. The stress measurements are complemented by medium energy electron diffraction (MEED), Auger electron spectroscopy, and additional growth rate monitoring by a quartz microbalance. A shielded filament is used to allow for simultaneous stress and MEED measurements at high substrate temperatures. A computer-controlled mirror scans an excimer laser beam over a stationary PLD target. This avoids mechanical noise originating from rotating PLD targets, and the setup does not suffer from limited lifetime issues of ultra high vacuum (UHV) rotary feedthroughs.

  20. Cantilever stress measurements for pulsed laser deposition of perovskite oxides at 1000 K in an oxygen partial pressure of 10(-4) millibars.

    PubMed

    Premper, J; Sander, D; Kirschner, J

    2015-03-01

    An in situ stress measurement setup using an optical 2-beam curvature technique is described which is compatible with the stringent growth conditions of pulsed laser deposition (PLD) of perovskite oxides, which involves high substrate temperatures of 1000 K and oxygen partial pressures of up to 1 × 10(-4) millibars. The stress measurements are complemented by medium energy electron diffraction (MEED), Auger electron spectroscopy, and additional growth rate monitoring by a quartz microbalance. A shielded filament is used to allow for simultaneous stress and MEED measurements at high substrate temperatures. A computer-controlled mirror scans an excimer laser beam over a stationary PLD target. This avoids mechanical noise originating from rotating PLD targets, and the setup does not suffer from limited lifetime issues of ultra high vacuum (UHV) rotary feedthroughs. PMID:25832240

  1. Partial pressures of oxygen and carbon dioxide, pH, and concentrations of bicarbonate, lactate, and glucose in pleural fluid from horses.

    PubMed

    Brumbaugh, G W; Benson, P A

    1990-07-01

    Samples of pleural fluid from 20 horses with effusive pleural diseases of various causes were evaluated; samples from 19 horses were used for the study. There were differences for pH (P = 0.001) and partial pressure of oxygen (PO2) between arterial blood and nonseptic pleural fluid (P = 0.0491), but there were no differences for pH, PO2, partial pressure of carbon dioxide (PCO2), and concentrations of bicarbonate (HCO3-), lactate, and glucose between venous blood and nonseptic pleural fluid. Paired comparisons of venous blood and nonseptic pleural fluid from the same horse indicated no differences. There were differences (P = 0.0001, each) for pH, PO2, PCO2, and concentrations of HCO3- between arterial blood and septic pleural fluid. Differences also existed for pH (P = 0.0001), PCO2 (P = 0.0003), and concentrations of HCO3- (P = 0.0001), lactate (P = 0.0051), and glucose (P = 0.0001) between venous blood and septic pleural fluid. Difference was not found for values of PO2 between venous blood and septic pleural fluid, although 4 samples of septic pleural fluid contained virtually no oxygen. Paired comparisons of venous blood and septic pleural fluid from the same horse revealed differences (P less than 0.05) for all values, except those for PO2. These alterations suggested functional and physical compartmentalization that separated septic and healthy tissue. Compartmentalization and microenvironmental factors at the site of infection should be considered when developing therapeutic strategies for horses with septic pleural disease. PMID:2389879

  2. Acetylene Fermentation: Relevance to Primordial Biogeochemistry and the Search for Life in the Outer Solar System

    NASA Astrophysics Data System (ADS)

    Oremland, R. S.; Baesman, S. M.; Miller, L. G.

    2014-02-01

    Acetylene supports the growth of some terrestrial anaerobes. The reaction is highly exothermic. The abundance of acetylene in the methane-rich planet(oid)s of the outer solar system could represent a means of nourishment for resident alien microbes.

  3. Annealing temperature and O2 partial pressure dependence of T(sub c) in HgBa2CuO(4+delta)

    NASA Technical Reports Server (NTRS)

    Xiong, Q.; Cao, Y.; Chen, F.; Xue, Y. Y.; Chu, C. W.

    1994-01-01

    Samples of HgBa2CuO(4+delta) (Hg-1201) were annealed under various conditions. After carefully controlling annealing time, annealing temperature (T(sub a)) and O2 partial pressure (P(sub 0)), we were able to find the reversible annealing conditions for Hg-1201. Under 1 atm O2 at 260 C less than or equal to T(sub a) less than or equal to 400 C, the obtained T(sub c) is nearly the same (approximately 97 K). However, it decreases quickly with T(sub a) greater than 300 C in high vacuum (P(sub 0) approximately 10(exp -8) atm), and reaches zero at T(sub a) = 400 C. On the other hand, T(sub c) decreases with the decrease of T(sub a) in high-pressure O2 (approximately 500 atm) and reaches approximately 20 K at about 240 C. In the entire annealing region, the oxygen surplus varies significantly from 0.03 to 0.4, and a wide range of T(sub c) variation (0 goes to 97 K goes to 20 K) was obtained with anion doping alone.

  4. Self-consistent particle modeling of radio frequency discharge in Ar/O{sub 2} mixtures: Effects of crossed electric and magnetic fields and partial pressure

    SciTech Connect

    Benyoucef, Djilali; Yousfi, Mohammed; Belmadani, Bachir

    2011-04-15

    A particle-in-cell/Monte Carlo model is developed to study and analyze the electrical characteristics of the nonequilibrium plasma created by radio frequency (RF) discharge in Ar/O{sub 2} mixtures in the presence of crossed electric and magnetic fields. The method of collision treatment is based on an optimized estimation of the free time flight. The needed basic data--more specifically, the ion-neutral cross sections--are determined first. The simulation conditions are 50 mTorr for the total gas pressure and 200 V for the peak of the RF voltage at a frequency of 13.56 MHz. The magnetic field is varied from 0 to 50 G. The effect of the partial pressure ratio of O{sub 2} in the mixture and the effect of the magnitude of the magnetic field are discussed. In particular, the results show an increase of the plasma density that is ten times higher in the presence of a magnetic field.

  5. Numerical study of ethylene and acetylene laminar flame speeds

    SciTech Connect

    Marinov, N.M.; Pitz, W.J.; Westbrook, C.K.

    1995-03-01

    Detailed chemical kinetic computations for ethylene-air and acetylene-air mixtures have been performed to simulate laminar flame speeds. Sensitivity analysis was applied to determine those reactions which strongly influence flame propagation. In ethylene-air mixtures, the C{sub 2}H{sub 3} + O{sub 2} = CH{sub 2}CHO + O reaction was one of the most sensitive reactions in the C{sub 2}H{sub 4}/C{sub 2}H{sub 3} submechanism and therefore this reaction was very important to ethylene flame propagation. This reaction was not considered in previously reported mechanisms used to model ethylene-air flame propagation. In acetylene-air mixtures, the C{sub 2}H{sub 2}+O {yields} Products, HCCO+H=CH{sub 2}(s)+CO, HCCO+O{sub 2}=CO{sub 2}+CO+H, H+C{sub 2}H{sub 2}(+M) = C{sub 2}H{sub 3}(+M) and CH{sub 2}(s)+C{sub 2}H{sub 2} = H{sub 2}CCCH+H were the most sensitive reactions in the C{sub 2}H{sub 2}/HCCO / CH{sub 2}(s) reaction set.

  6. Pleomorphism and acetylene-reducing activity of free-living rhizobia.

    PubMed Central

    Kaneshiro, T; Baker, F L; Johnson, D E

    1983-01-01

    Cowpea-type Rhizobium sp. strain 32H1 and Rhizobium japonicum USDA 26 and 110 grown on a glutamate-mannitol-gluconate agar medium showed increases in the number of pleomorphic cells coincident with their acetylene-reducing activity. Pleomorphs appeared to be inhibited in growth nonuniformly, because acetylene-reducing cultures were mixtures of rod, branched (V, Y, and T), and other irregularly shaped cells. In contrast, strain USDA 10 consistently failed to reduce acetylene, even though it also could grow and yield pleomorphic cells under various conditions. With minimal inhibitory supplements (5 micrograms per ml of medium) of nalidixic acid and novobiocin as cell division inhibitors, an increase in pleomorphic cells was observed, but the inhibited cultures displayed lower acetylene-reducing activity. A study of pleomorphic cells derived in different ways indicated that not all pleomorphs reduce acetylene. Images PMID:6822472

  7. Ultrafast hydrogen migration in acetylene cation driven by non-adiabatic effects.

    PubMed

    Madjet, Mohamed El-Amine; Li, Zheng; Vendrell, Oriol

    2013-03-01

    Non-adiabatic dynamics of the acetylene cation is investigated using mixed quantum-classical dynamics based on trajectory surface hopping. To describe the non-adiabatic effects, two surface hopping methods are used, namely, Tully's fewest switches and Landau-Zener surface hopping. Similarities and differences between the results based on those two methods are discussed. We find that the photoionization of acetylene into the first excited state A(2)Σg(+) drives the molecule from the linear structure to a trans-bent structure. Through a conical intersection the acetylene cation can relax back to either the ground state of acetylene or vinylidene. We conclude that hydrogen migration always takes place after non-radiative electronic relaxation to the ground state of the monocation. Based on the analysis of correlation functions we identify coherent oscillations between acetylene and vinylidene with a period of about 70 fs after the electronic relaxation. PMID:23485298

  8. Effects of water-saturation on strength and ductility of three igneous rocks at effective pressures to 50 MPA and temperatures to partial melting

    SciTech Connect

    Bauer, S.J.; Friedman, M.; Handin, J.

    1981-01-01

    The short-term failure strengths and strains at failure of room-dry and water-saturated, cylindrical specimens (2 by 4 cm) of Charcoal Granodiorite (CG), Mt. Hood Andesite (MHA), and Cuerbio Basalt (CB) at a strain rate of 10/sup -4/s/sup -1/, at effective confining pressures of 0, 50, and 100 MPa and at temperatures to partial melting were investigated. Data from water-saturated specimens of the granodiorite and andesite, compared to room-dry counterparts, indicate (1) the pore pressures are essentially communicated throughout each test specimen so that they are fully effective; (2) at P/sub e/ = 0 and 50 MPa the granodiorite does not water-weaken; (3) at these same effective pressures the more porous and finer-grained andesite begins to exhibit water-weakening at about 600/sup 0/C; (4) at P/sub e/ = 0 and 870 to 900/sup 0/C the andesite's strength averages 20 MPa while the strength of dry specimens at the same P and T exhibit a strength of 100 MPa; (5) at P/sub e/ = 50 MPa compared to 160 MPa dry; (6) the basalt at P/sub e/ = 0, appears to be water-weakened at 800/sup 0/C; (7) water saturated specimens deformed at temperatures less than that of melting exhibit ultimate strengths at less than 2% shortening and then work-soften along faults; (8) again as do the dry counterparts, the wet specimens deform primarily by microscopic fracturing that coalesces into one or more macroscopic faults; and (9) the temperature for incipient melting of the andesite is decreased >150/sup 0/C in the water-saturated tests.

  9. Equilibrium partial pressures, thermodynamic properties of aqueous and solid phases, and Cl{sub 2} production from aqueous HCl and HNO{sub 3} and their mixtures

    SciTech Connect

    Massucci, M.; Clegg, S.L.; Brimblecombe, P.

    1999-05-27

    Equilibrium total pressures have been measured above aqueous HNO{sub 3} and aqueous HCl using a capacitance manometer. Equilibrium partial pressures of the acids have also been determined, by mass spectrometry, from 274.8 to 234.6 K for both HCl solutions, and from 265.0 to 240.1 K for 15.73 mol kg{sup {minus}1} HNO{sub 3}. Results are generally consistent with model predictions, though with small systematic deviations for the total pressure measurements over aqueous HCl at about 220 K. Mixtures of HCl{minus}HNO{sub 3}{minus}H{sub 2}O composition yielded measured total pressures orders of magnitude greater than predicted for the gases H{sub 2}O, HNO{sub 3}, and HCl. Mass spectrometric determinations and equilibrium thermodynamic calculations suggest that Cl{sub 2} and NOCl were produced by the reaction: 4H{sup +}{sub aq} + NO{sub 3}{sup {minus}}{sub aq} + 3Cl{sup {minus}}{sub aq} {r_equilibrium} NOCl{sub aq} + Cl{sub 2(aq)} + 2H{sub 2}O{sub (1)}, which is known to occur in aqua regia. Calculations for aqueous solutions of stratospheric aerosol composition suggest, purely on equilibrium grounds, that the reaction could be a source of active chlorine in the stratosphere. The correlation of Clegg and Brimblecombe of the thermodynamic properties of aqueous HNO{sub 3} activities has been revised, and vapor pressure products assessed from literature studies. The activity product for the reaction HNO{sub 3}{center_dot}2H{sub 2}O{sub (cr)} {r_equilibrium} H{sup +}{sub (aq)} + NO{sub 3}{sup {minus}}{sub (aq)} + 2H{sub 2}O{sub (1)} has also been determined. The model of Carslaw et al. has been revised for the solubility of HBr in aqueous H{sub 2}SO{sub 4} to stratospheric temperatures.

  10. Rationally tuned micropores within enantiopure metal-organic frameworks for highly selective separation of acetylene and ethylene

    SciTech Connect

    Xiang, Sheng-Chang; Zhang, Zhangjing; Zhao, Cong-Gui; Hong, Kunlun; Zhao, Xuebo; Ding, De-Rong; Xie, Ming-Hua; Wu, Chuan-De; Madhab, Das; Gill, Rachel; Thomas, K Mark; Chen, Banglin

    2011-01-01

    Separation of acetylene and ethylene is an important industrial process because both compounds are essential reagents for a range of chemical products and materials. Current separation approaches include the partial hydrogenation of acetylene into ethylene over a supported Pd catalyst, and the extraction of cracked olefins using an organic solvent; both routes are costly and energy consuming. Adsorption technologies may allow separation, but microporous materials exhibiting highly selective adsorption of C{sub 2}H{sub 2}/C{sub 2}H{sub 4} have not been realized to date. Here, we report the development of tunable microporous enantiopure mixed-metal-organic framework (M'MOF) materials for highly selective separation of C{sub 2}H{sub 2} and C{sub 2}H{sub 4}. The high selectivities achieved suggest the potential application of microporous M'MOFs for practical adsorption-based separation of C{sub 2}H{sub 2}/C{sub 2}H{sub 4}.

  11. Effects of water-saturation on strength and ductility of three igneous rocks at effective pressures to 50 MPa and temperatures to partial melting

    SciTech Connect

    Bauer, S.J.; Friedman, M.; Handin, J.

    1981-01-01

    Instantaneous-failure strengths and ductilities of water-saturated cylindrical specimens of Charcoal Granodiorite, Mount Hood Andesite, and Cuerbio Basalt are determined at a strain rate of 10{sup -4}s{sup -1} and at effective confining pressures (Pe) of 0 and 50 MPa and at temperatures to partial melting. The data indicate: (1) at Pe = 0 and 50 MPa (Pc and Pp of 50 MPa and of 100 and 50 MPa, respectively) the granodiorite does not water-weaken; (2) at these same Pe the more porous and finer-grained andesite begins to exhibit water-weakening at about 600/sup 0/C; (3) at Pe = 0 and 870-900{sup 0}C the andesite's wet strength averages 20 MPa compared to 100 MPa, dry; (4) at Pe = 50 MPa and 920{sup 0}C its wet strength is 45 MPa compared to 160 MPa dry; (5) at Pe = 0, the basalt appears to be water-weakened above 800{sup 0}C; (6) water-saturated specimens deformed at temperatures less than T{sub m} exhibit ultimate strengths at less than 2 percent shortening and then work-soften along faults; and (7) both dry and wet specimens deform primarily by brittle fracture. Extrapolations indicate: (1) crystalline rocks should be drillable because they remain brittle until partial melting occurs, and penetration rates should increase with temperature because there is a corresponding decrease in brittle fracture strength; (2) boreholes in ''water-filled'' holes will be stable to >10 km at temperatures 10 km; and (4) open boreholes in the andesite are apt to be much less stable, and at similar temperatures would fail at 2 to 5-km depth.

  12. Reconstruction of pH and partial pressure of carbon dioxide during the Mesozoic era period using boron and oxygen isotopic compositions of fresh ammonoids & nautiloids

    NASA Astrophysics Data System (ADS)

    Kawahata, Hodaka; Fukushima, Ayaka; Moriya, Kazuyori; Ishikawa, Tsuyoshi; Suzuki, Atsushi; Tanabe, Kazushige

    2013-04-01

    The increase of partial pressure of carbon dioxide (pCO2) in the atmosphere induces global warming and ocean acidification at the modern condition. The reconstruction of pCO2 during the geological time is required together with proxy calibration by laboratory experiments to predict the future environments. Boron isotopic ratio is an excellent proxy for pH and the relevant partial pressure of carbon dioxide in the seawater (PCO2). This study is the first to quantify pH dependence of delta 11B of the ammonoids and nautiloids mainly in the Cretaceous and in Jurassic (70-162 Ma), which are expected to be much warmer due to higher PCO2. However, no reliable reconstruction data using foraminiferal delta 11B before Cenozoic era has been reported. We used the very fresh aragonite shells of ammonoids and nautiloids by big advantages. Since aragonite changes into secondary calcite by diagenesis, it is easy and effective to identify the degree of alteration at each sample by measuring calcite/aragonite ratio. Also we carefully conducted the assessment of secondary alteration from three perspectives: 1) Determination of calcite/aragonite ratio by X-ray diffraction (XRD), 2) Observation of microstructures of the nacreous layers by scanning electron microscope (SEM), and 3) Measurement of trace element contents and stable isotope ratios. We conducted high precision boron isotope analysis of biogenic carbonates with +/- 0.1 per mil reproducibility by adopting positive thermal ionization mass spectrometry (P-TIMS) methods. Also we analyzed delta 18O to estimate paleo-temperature, at which biogenic aragonite was formed. Combination of delta 11B and delta 18O of biogenic aragonite in 80 Ma and 86 Ma revealed that deeper dwellers showed lower delta 11B values, which corresponded to lower pH. This feature is consistent with those observed in the modern vertical water column. The respective shallow water temperature was 19.7 and 19.1 centigrade. Based on these results, the

  13. Partial molar volumes of NiO and CoO liquids: implications for the pressure dependence of metal-silicate partitioning

    NASA Astrophysics Data System (ADS)

    Courtial, Philippe; Gottsmann, Joachim; Holzheid, Astrid; Dingwell, Donald B.

    1999-08-01

    Volumetric measurements have been conducted on 7 Ni- and Co-containing sodium disilicate liquids within a compositional range varying from 0 to 9 mol% of NiO and from 0 to 23 mol% of CoO and over a large temperature interval (i.e., above their respective glass transition temperature and up to at least 1473 K). Their molar volumes and thermal expansivities have been determined by combining high-temperature measurements using the Pt-based double-bob Archimedean method and low-temperature measurements using the method described by Webb et al. [S.L. Webb, R. Knoche, D.B. Dingwell, Determination of silicate liquid thermal expansivity using dilatometry and calorimetry, Eur. J. Mineral. 4 (1992) 95-104] based on an assumed equivalence of the relaxation of volume and enthalpy at the glass transition. The molar volume of the present liquids decreases with increasing NiO and CoO contents and the Co-containing liquids exhibit a greater molar volume than the Ni-containing liquids at equivalent molar concentrations. The present results were analysed using a regression equation from which the partial molar volume of NiO and CoO liquids was obtained by the least squares method. This procedure yields partial molar volumes valid over the entire temperature range of 11.506 ± 0.687 and 14.884 ± 0.149 cm 3/mol and temperature derivatives of 2.684 ± 1.6 × 10 -3 and 1.441 ± 0.4 × 10 -3 cm 3/mol K, respectively for NiO and CoO at 800 K. The behavior of M-Fe metal-silicate exchange partition coefficient (M = Ni, Co), based on present molar volume determinations, has been estimated as a function of pressure over a wide temperature range. The metal-silicate exchange partition coefficients of both Ni and Co decrease with increasing pressure within the entire temperature range considered in this study (i.e., 800-3000 K).

  14. Infrared spectroscopy and Mie scattering of acetylene aerosols formed in a low temperature diffusion cell

    NASA Technical Reports Server (NTRS)

    Dunder, T.; Miller, R. E.

    1990-01-01

    A method is described for forming and spectroscopically characterizing cryogenic aerosols formed in a low temperature gas cell. By adjusting the cell pressure, gas composition and flow rate, the size distribution of aerosol particles can be varied over a wide range. The combination of pressure and flow rate determine the residence time of the aerosols in the cell and hence the time available for the particles to grow. FTIR spectroscopy, over the range from 600/cm to 6000/cm, is used to characterize the aerosols. The particle size distribution can be varied so that, at one extreme, the spectra show only absorption features associated with the infrared active vibrational bands and, at the other, they display both absorption and Mie scattering. In the latter case, Mie scattering theory is used to obtain semiquantitative aerosol size distributions, which can be understood in terms of the interplay between nucleation and condensation. In the case of acetylene aerosols, the infrared spectra suggest that the particles exist in the high temperature cubic phase of the solid.

  15. A first principles study of the acetylene-water interaction

    SciTech Connect

    Tzeli, Demeter; Mavridis, Aristides; Xantheas, Sotiris S.

    2000-04-08

    We present an extensive study of the stationary points on the acetylene-water (AW) ground-state potential energy surface (PES) aimed in establishing accurate energetics for the two different bonding scenarios that are considered. Those include arrangements in which water acts either as a proton acceptor from one of the acetylene hydrogen atoms or a proton donor to the triple bond. We used a hierarchy of theoretical methods to account for electron correlation [MP2 (second-order Moller-Plesset), MP4 (fourth-order Moller-Plesset), and CCSD(T) (coupled-cluster single double triple)] coupled with a series of increasing size augmented correlation consistent basis sets (aug-cc-pVnZ, n=2,3,4). We furthermore examined the effect of corrections due to basis set superposition error (BSSE). We found that those have a large effect in altering the qualitative features of the PES of the complex. They are responsible for producing a structure of higher (C{sub 2v}) symmetry for the global minimum. Zero-point energy (ZPE) corrections were found to increase the stability of the C{sub 2v} arrangement. For the global (water acceptor) minimum of C{sub 2v} symmetry our best estimates are {delta}E{sub e}=-2.87 kcal/mol ({delta}E{sub 0}=-2.04 kcal/mol) and a van der Waals distance of R{sub e}=2.190 Aa. The water donor arrangement lies 0.3 kcal/mol (0.5 kcal/mol including ZPE corrections) above the global minimum. The barrier for its isomerization to the global minimum is E{sub e}=0.18 kcal/mol; however, inclusion of BSSE- and ZPE-corrections destabilize the water donor arrangement suggesting that it can readily convert to the global minimum. We therefore conclude that there exists only one minimum on the PES in accordance with previous experimental observations. To this end, vibrational averaging and to a lesser extend proper description of intermolecular interactions (BSSE) were found to have a large effect in altering the qualitative features of the ground-state PES of the acetylene

  16. CO2 Solubility in Natural Rhyolitic Melts at High Pressures - Implications for Carbon Flux in Subduction Zones by Sediment Partial Melts

    NASA Astrophysics Data System (ADS)

    Duncan, M. S.; Dasgupta, R.

    2011-12-01

    Partial melts of subducting sediments is thought to be a critical agent in carrying trace elements and water to arc basalt source regions. For subduction zones that contain significant amount of carbonates in ocean-floor sediments, sediment melts likely also act as a carrier of CO2. However, the CO2 carrying capacity of natural rhyolitic melts at sub-arc depths remains unconstrained. We conducted experiments on a synthetic composition, similar to average, low-degree experimental partial melt of pelitic sediments. The composition was constructed with reagent grade oxides and carbonates, the source of excess CO2. Experiments were conducted between 1 and 3 GPa at 1200 °C in Au80Pd20 capsules using a piston cylinder apparatus with a half-inch BaCO3 assembly at Rice University. Quench products showed glasses with bubbles, the latter suggesting saturation of the melt with a CO2-rich vapor phase. Oxygen fugacity during the experiments was not strictly controlled but the presence of CO2 bubbles and absence of graphite indicates fO2 above the CCO buffer. Major element concentrations of glasses were measured using EPMA. The CO2 and H2O contents of experimental doubly polished (50-110 μm), bubble-free portions of the glass chips were determined using a Thermo Nicolet Fourier Transform Infrared Spectrometer. Spectra were recorded with a resolution of 4 cm-1, 512 scans, from 650 to 4000 cm-1, under a nitrogen purge to eliminate atmospheric gases. Dissolved volatile concentrations were quantified using the Beer-Lambert law and linear molar absorption coefficients from previous studies [1, 2]. Total dissolved carbon dioxide of experimental glasses was determined from the intensity of the ν3 antisymmetric stretch bands of CO32- at 1430 cm-1 and CO2mol at 2348 cm-1. Dissolved water content of experimental glasses was determined from the intensity of O-H stretching at 3520 cm-1. Estimated total CO2 concentrations at 3 GPa are in the range of 1-2 wt%, for melts with H2O contents

  17. Correlation between hydrogen bond basicity and acetylene solubility in room temperature ionic liquids.

    PubMed

    Palgunadi, Jelliarko; Hong, Sung Yun; Lee, Jin Kyu; Lee, Hyunjoo; Lee, Sang Deuk; Cheong, Minserk; Kim, Hoon Sik

    2011-02-10

    Room temperature ionic liquids (RTILs) are proposed as the alternative solvents for the acetylene separation in ethylene generated from the naphtha cracking process. The solubility behavior of acetylene in RTILs was examined using a linear solvation energy relationship based on Kamlet-Taft solvent parameters including the hydrogen-bond acidity or donor ability (α), the hydrogen-bond basicity or acceptor ability (β), and the polarity/polarizability (π*). It is found that the solubility of acetylene linearly correlates with β value and is almost independent of α or π*. The solubility of acetylene in RTILs increases with increasing hydrogen-bond acceptor (HBA) ability of the anion, but is little affected by the nature of the cation. Quantum mechanical calculations demonstrate that the acidic proton of acetylene specifically forms hydrogen bond with a basic oxygen atom on the anion of a RTIL. On the other hand, although C-H···π interaction is plausible, all optimized structures indicate that the acidic protons on the cation do not specifically associate with the π cloud of acetylene. Thermodynamic analysis agrees well with the proposed correlation: the higher the β value of a RTIL is, the more negative the enthalpy of acetylene absorption in the RTIL is. PMID:21218815

  18. Organogermanium Chemistry: Germacyclobutanes and digermane Additions to Acetylenes

    SciTech Connect

    Andrew Michael Chubb

    2003-12-12

    This dissertation comprises two main research projects. The first project, presented in Chapter 1, involves the synthesis and thermochemistry of germacyclobutanes (germetanes). Four new germetanes (spirodigermetane, diallylgermetane, dichlorogermetane, and germacyclobutane) have been synthesized using a modified di-Grignard synthesis. Diallylgermetane is shown to be a useful starting material for obtaining other germetanes, particularly the parent germetane, germacyclobutane. The gas-phase thermochemistries of spirodigermetane, diallylgermetane and germacyclobutane have been explored via pulsed stirred-flow reactor (SFR) studies, showing remarkable differences in decomposition, depending on the substitution at the germanium atom. The second project investigates the thermochemical, photochemical, and catalytic additions of several digermanes to acetylenes. The first examples of thermo- and photochemical additions of Ge-Ge bonds to C{triple_bond}C are demonstrated. Mechanistic investigations are described and comparisons are made to analogous disilane addition reactions, previously studied in their group.

  19. Acetylene fuel from atmospheric CO2 on Mars

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.; Linne, Diane L.

    1992-01-01

    The Mars mission scenario proposed by Baker and Zubrin (1990) intended for an unmanned preliminary mission is extended to maximize the total impulse of fuel produced with a minimum mass of hydrogen from Earth. The hydrogen along with atmospheric carbon dioxide is processed into methane and oxygen by the exothermic reaction in an atmospheric processing module. Use of simple chemical reactions to produce acetylene/oxygen rocket fuel on Mars from hydrogen makes it possible to produce an amount of fuel that is nearly 100 times the mass of hydrogen brought from earth. If such a process produces the return propellant for a manned Mars mission, the required mission mass in LEO is significantly reduced over a system using all earth-derived propellants.

  20. Inclusion of 13C and D in protonated acetylene

    NASA Astrophysics Data System (ADS)

    Fortenberry, Ryan C.; Roueff, Evelyne; Lee, Timothy J.

    2016-04-01

    The rovibrational spectrum of cyclic, protonated acetylene has been established. The improvement in modern telescopes coupled with the different branching ratios in reaction models welcomes study of 13C-substitution for C2H3+. Quartic force fields (QFFs) have been previously utilized to predict the antisymmetric HCCH stretch in standard c-C2H3+ to within 0.1 cm-1 of experiment and are employed here to generate rovibrational insights for the 13C isotopologues. The zero-point energies are also given for the cyclic and 'Y'-shaped isomers for both 13C and D substitutions. Vibrational intensities and the dipole moments are provided in order to characterize more fully this simple cation.

  1. Ultrafast Extreme Ultraviolet Induced Isomerization of Acetylene Cations

    SciTech Connect

    Jiang, Y.; Rudenko, Artem; Herrwerth, O.; Foucar, L.; Kurka, M.; Kuhnel, K.; Lezius, M.; Kling, Matthias; van Tilborg, Jeroen; Belkacem, Ali; Ueda, K.; Dusterer, S.; Treusch, R.; Schroter, Claus-Dieter; Moshammer, Robbert; Ullrich, Joachim

    2011-06-17

    Ultrafast isomerization of acetylene cations ([HC = CH]{sup +}) in the low-lying excited A{sup 2}{Sigma}{sub g}{sup +} state, populated by the absorption of extreme ultraviolet (XUV) photons (38 eV), has been observed at the Free Electron Laser in Hamburg, (FLASH). Recording coincident fragments C{sup +} + CH{sub 2}{sup +} as a function of time between XUV-pump and -probe pulses, generated by a split-mirror device, we find an isomerization time of 52 {+-} 15 fs in a kinetic energy release (KER) window of 5.8 < KER < 8 eV, providing clear evidence for the existence of a fast, nonradiative decay channel.

  2. Adhesive and composite evaluation of acetylene-terminated phenylquinoxaline resins

    NASA Technical Reports Server (NTRS)

    Hergenrother, P. M.

    1981-01-01

    A series of acetylene-terminated phenylquinoxaline (ATPQ) oligomers of various molecular weights were prepared and subsequently chain extended by the thermally induced reaction of the ethynyl groups. The processability and thermal properties of these oligomers and their cured resins were compared with that of a relatively high molecular weight linear polyphenylquinoxaline (PPQ) with the same chemical backbone. The ATPQ oligomers exhibited significantly better processability than the linear PPQ but the PPQ displayed substantially better thermooxidative stability. Adhesive (Ti/Ti) and composite (graphite filament reinforcement) work was performed to evaluate the potential of these materials for structural applications. The PPQ exhibited better retention of adhesive and laminate properties than the ATPQ resins at 260 C after aging for 500 hr at 260 C in circulating air.

  3. Ultrafast Extreme Ultraviolet Induced Isomerization of Acetylene Cations

    SciTech Connect

    Jiang, Y. H.; Kurka, M.; Kuehnel, K. U.; Schroeter, C. D.; Moshammer, R.; Rudenko, A.; Foucar, L.; Herrwerth, O.; Lezius, M.; Kling, M. F.; Tilborg, J. van; Belkacem, A.; Ueda, K.; Duesterer, S.; Treusch, R.; Ullrich, J.

    2010-12-31

    Ultrafast isomerization of acetylene cations ([HC=CH]{sup +}) in the low-lying excited A{sup 2}{Sigma}{sub g}{sup +} state, populated by the absorption of extreme ultraviolet (XUV) photons (38 eV), has been observed at the Free Electron Laser in Hamburg, (FLASH). Recording coincident fragments C{sup +}+CH{sub 2}{sup +} as a function of time between XUV-pump and -probe pulses, generated by a split-mirror device, we find an isomerization time of 52{+-}15 fs in a kinetic energy release (KER) window of 5.8

  4. Acetylene as Fast Food: Implications for Development of Life on Anoxic Primordial Earth and in the Outer Solar System

    NASA Astrophysics Data System (ADS)

    Oremland, Ronald S.; Voytek, Mary A.

    2008-02-01

    Acetylene occurs, by photolysis of methane, in the atmospheres of jovian planets and Titan. In contrast, acetylene is only a trace component of Earth's current atmosphere. Nonetheless, a methane-rich atmosphere has been hypothesized for early Earth; this atmosphere would also have been rich in acetylene. This poses a paradox, because acetylene is a potent inhibitor of many key anaerobic microbial processes, including methanogenesis, anaerobic methane oxidation, nitrogen fixation, and hydrogen oxidation. Fermentation of acetylene was discovered 25 years ago, and Pelobacter acetylenicus was shown to grow on acetylene by virtue of acetylene hydratase, which results in the formation of acetaldehyde. Acetaldehyde subsequently dismutates to ethanol and acetate (plus some hydrogen). However, acetylene hydratase is specific for acetylene and does not react with any analogous compounds. We hypothesize that microbes with acetylene hydratase played a key role in the evolution of Earth's early biosphere by exploiting an available source of carbon from the atmosphere and in so doing formed protective niches that allowed for other microbial processes to flourish. Furthermore, the presence of acetylene in the atmosphere of a planet or planetoid could possibly represent evidence for an extraterrestrial anaerobic ecosystem.

  5. Acetylene as fast food: Implications for development of life on anoxic primordial earth and in the outer solar system

    USGS Publications Warehouse

    Oremland, R.S.; Voytek, M.A.

    2008-01-01

    Acetylene occurs, by photolysis of methane, in the atmospheres of jovian planets and Titan. In contrast, acetylene is only a trace component of Earth's current atmosphere. Nonetheless, a methane-rich atmosphere has been hypothesized for early Earth; this atmosphere would also have been rich in acetylene. This poses a paradox, because acetylene is a potent inhibitor of many key anaerobic microbial processes, including methanogenesis, anaerobic methane oxidation, nitrogen fixation, and hydrogen oxidation. Fermentation of acetylene was discovered 25 years ago, and Pelobacter acetylenicus was shown to grow on acetylene by virtue of acetylene hydratase, which results in the formation of acetaldehyde. Acetaldehyde subsequently dismutates to ethanol and acetate (plus some hydrogen). However, acetylene hydratase is specific for acetylene and does not react with any analogous compounds. We hypothesize that microbes with acetylene hydratase played a key role in the evolution of Earth's early biosphere by exploiting an available source of carbon from the atmosphere and in so doing formed protective niches that allowed for other microbial processes to flourish. Furthermore, the presence of acetylene in the atmosphere of a planet or planetoid could possibly represent evidence for an extraterrestrial anaerobic ecosystem. ?? Mary Ann Liebert, Inc.

  6. Acetylene as fast food: implications for development of life on anoxic primordial Earth and in the outer solar system.

    PubMed

    Oremland, Ronald S; Voytek, Mary A

    2008-02-01

    Acetylene occurs, by photolysis of methane, in the atmospheres of jovian planets and Titan. In contrast, acetylene is only a trace component of Earth's current atmosphere. Nonetheless, a methane-rich atmosphere has been hypothesized for early Earth; this atmosphere would also have been rich in acetylene. This poses a paradox, because acetylene is a potent inhibitor of many key anaerobic microbial processes, including methanogenesis, anaerobic methane oxidation, nitrogen fixation, and hydrogen oxidation. Fermentation of acetylene was discovered approximately 25 years ago, and Pelobacter acetylenicus was shown to grow on acetylene by virtue of acetylene hydratase, which results in the formation of acetaldehyde. Acetaldehyde subsequently dismutates to ethanol and acetate (plus some hydrogen). However, acetylene hydratase is specific for acetylene and does not react with any analogous compounds. We hypothesize that microbes with acetylene hydratase played a key role in the evolution of Earth's early biosphere by exploiting an available source of carbon from the atmosphere and in so doing formed protective niches that allowed for other microbial processes to flourish. Furthermore, the presence of acetylene in the atmosphere of a planet or planetoid could possibly represent evidence for an extraterrestrial anaerobic ecosystem. PMID:18199006

  7. Ionization of large homogeneous and heterogeneous clusters generated in acetylene-Ar expansions: cluster ion polymerization.

    PubMed

    Kočišek, J; Lengyel, J; Fárník, M

    2013-03-28

    Pure acetylene and mixed Ar-acetylene clusters are formed in supersonic expansions of acetylene/argon mixtures and analysed using reflectron time-of-flight mass spectrometer with variable electron energy ionization source. Acetylene clusters composed of more than a hundred acetylene molecules are generated at the acetylene concentration of ≈8%, while mixed species are produced at low concentrations (≈0.7%). The electron energy dependence of the mass spectra revealed the ionization process mechanisms in clusters. The ionization above the threshold for acetylene molecule of 11.5 eV results in the main ionic fragment progression (C2H2)n(+). At the electron energies ≥21.5 eV above the CH+CH(+) dissociative ionization limit of acetylene the fragment ions nominally labelled as (C2H2)nCH(+), n ≥ 2, are observed. For n ≤ 7 these fragments correspond to covalently bound ionic structures as suggested by the observed strong dehydrogenation [(C2H2)n - k × H](+) and [(C2H2)nCH - k × H](+). The dehydrogenation is significantly reduced in the mixed clusters where evaporation of Ar instead of hydrogen can stabilize the nascent molecular ion. The C3H3(+) ion was previously assigned to originate from the benzene molecular ion; however, the low appearance energy of ≈13.7 eV indicates that a less rigid covalently bound structure of C6H6(+) ion must also be formed upon the acetylene cluster electron ionization. The appearance energy of Arn(C2H2)(+) fragments above ≈15.1 eV indicates that the argon ionization is the first step in the fragment ion production, and the appearance energy of Arn≥2(C2H2)m≥2(+) at ≈13.7 eV is discussed in terms of an exciton transfer mechanism. PMID:23556722

  8. Effects of elevated partial pressure of carbon dioxide and season of the year on forage quality and cyanide concentration of Trifolium repens L. from a FACE experiment

    NASA Astrophysics Data System (ADS)

    Frehner, Marco; Lüscher, Andreas; Hebeisen, Thomas; Zanetti, Silvia; Schubiger, Franz; Scalet, Mario

    Differently managed (cutting frequency and N fertilization) Trifolium repens monocultures were grown at 60 Pa and 35 Pa of pCO 2 (partial pressure of CO 2) in a Free Air Carbon dioxide Enrichment (FACE) array. The concentrations of cyanide, digestible organic matter, crude protein and net energy for lactation were measured at different harvests throughout the growing season. The average cyanide concentrations differed significantly in the years and the seasons within the year; however, the concentrations were not affected by CO 2. Digestible organic matter, crude protein and net energy for lactation differed significantly with the seasons of the year and cutting frequencies. While digestible organic matter and net energy for lactation were not affected by elevated pCO 2, the concentration of crude protein decreased from 288 g kg -1 at ambient to 251 g kg -1 at elevated pCO 2. Since the crude protein concentration in herbage from Trifolium monocultures was very high even at elevated CO 2, it is suggested that this decrease in crude protein concentration does not negatively affect forage quality. We conclude that, in Trifolium herbage, the seasons of the year and management practices are more decisive for forage quality than changes in pCO 2. We shall discuss how forage quality and cyanide intake by ruminants may, however, be affected by CO 2-induced shifts in the proportion of species in mixed plant communities.

  9. Acetate production from lactose by Clostridium thermolacticum and hydrogen-scavenging microorganisms in continuous culture--effect of hydrogen partial pressure.

    PubMed

    Collet, Christophe; Gaudard, Olivier; Péringer, Paul; Schwitzguébel, Jean-Paul

    2005-08-22

    The effect of the addition of hydrogen-consuming microorganisms on the metabolism of Clostridium thermolacticum was studied. By growing this bacterium in continuous culture at 58 degrees C, on 29 mmol lactose l(-1) (10 gl(-1)) in the feed, with the H2-consuming microorganisms Methanothermobacter thermoautotrophicus and Moorella thermoautotrophica, the volumetric productivity of acetate was increased up to 3.9 mmol l(-1)h(-1) at a dilution rate of 0.058 h(-1). This was about three times higher than the maximal acetate volumetric productivity quantified when C. thermolacticum was cultivated alone. In the consortium, C. thermolacticum was the only species able to metabolize lactose; it produced not only acetate, but also hydrogen, carbon dioxide and lactate. The other species of the consortium were growing on these by-products. Meth. thermoautotrophicus played an important role as a very efficient hydrogen scavenger and decreased the hydrogen partial pressure drastically: hydrogen was converted to methane. Moor. thermoautotrophica converted lactate as well as hydrogen and carbon dioxide into acetate. As a consequence, lactose was efficiently consumed and the only organic product in the liquid phase was acetate. PMID:15992956

  10. Determination of octane numbers and Reid vapor pressure of commercial petroleum fuels using FT-Raman spectroscopy and partial least-squares regression analysis

    SciTech Connect

    Cooper, J.B.; Wise, K.L.; Groves, J.; Welch, W.T.

    1995-11-15

    A Fourier transform Raman spectrometer was used to collect the Raman spectra of 208 commercial petroleum fuels. The individual motor and research octane numbers (MON and RON, respectively) were determined experimentally using the industry standard ASTM knock engine method. Partial least-squares regression analysis was used to build regression models which correlate the Raman spectra of 175 of the fuels with the experimentally determined values for MON, RON, and pump octane number (the average of MON and RON) of the fuels. Each of the models was validated using leave-one-out validation. The standard errors of validation are 0.415, 0.535, and 0.410 octane units for MON, RON, and pump octane number, respectively. It is evident that the accuracy of the Raman determined values is limited by the accuracy of the training set used in creating the models. The Raman regression models were used to predict the octane numbers for the fuels which were not used to build the models. The results compare favorably with the leave-one-out validation. Also, it is demonstrated that the experimentally determined Reid vapor pressures are highly correlated with the Raman spectra of the fuel samples and can be predicted with a standard error of 0.568 psi. 11 refs., 6 figs., 2 tabs.

  11. Dissimilatory reduction of nitrate and nitrite in the bovine rumen: nitrous oxide production and effect of acetylene.

    PubMed Central

    Kaspar, H F; Tiedje, J M

    1981-01-01

    15N tracer methods and gas chromatography coupled to an electron capture detector were used to investigate dissimilatory reduction of nitrate and nitrite by the rumen microbiota of a fistulated cow. Ammonium was the only 15N-labeled end product of quantitative significance. Only traces of nitrous oxide were detected as a product of nitrate reduction; but in experiments with nitrite, up to 0.3% of the added nitrogen accumulated as nitrous oxide, but it was not further reduced. Furthermore, when 13NO3- was incubated with rumen microbiota virtually no [13N]N2 was produced. Acetylene partially inhibited the reduction of nitrite to ammonium as well as the formation of nitrous oxide. It is suggested that in the rumen ecosystem nitrous oxide is a byproduct of dissimilatory nitrite reduction to ammonium rather than a product of denitrification and that the latter process is absent from the rumen habitat. PMID:7224631

  12. Decreased alanine aminotransferase activity in serum of man during gamma-acetylenic-GABA treatment.

    PubMed

    Olsen, R; Hørder, M

    1980-06-01

    Decreasing concentrations of alanine aminotransferase were observed in nine patients receiving gamma-acetylenic-GABA, an inhibitor of GABA aminotransferase. In vitro studies showed that preincubation at 37 degrees C of serum with gamma-acetylenic-GABA and with urine from a patient receiving the drug led to inhibition of alanine aminotransferase. This inhibition of alanine aminotransferase by gamma-acetylenic-GABA was neutralized by 1-analine, the natural substrate for the enzyme. The mechanism of inhibition may be a competition between the drug and 1-alanine for the substrate binding site of the enzyme. PMID:7414257

  13. Inhibition of alkylbenzene biodegradation under denitrifying conditions by using the acetylene block technique.

    PubMed Central

    Hutchins, S R

    1992-01-01

    Addition of acetylene to microcosms simultaneously amended with nitrate and alkylbenzenes resulted in inhibition of the rate of alkylbenzene biodegradation under denitrifying conditions. Toluene, xylenes, and 1,2,4-trimethylbenzene were recalcitrant, whereas ethylbenzene was degraded at a slower rate than usual. Benzene was not degraded in either case. Addition of acetylene to microcosms preexposed to nitrate and alkylbenzenes produced similar inhibition. These data indicate that the activities of microorganisms that degrade alkylbenzenes under denitrifying conditions may be suppressed if the standard acetylene block technique is used to verify denitrifying activity. PMID:1444371

  14. Acetylene as a substrate in the development of primordial bacterial communities

    USGS Publications Warehouse

    Culbertson, C.W.; Strohmaier, F.E.; Oremland, R.S.

    1988-01-01

    The fermentation of atmospheric acetylene by anaerobic bacteria is proposed as the basis of a primordial heterotrophic food chain. The accumulation of fermentation products (acetaldehyde, ethanol, acetate and hydrogen) would create niches for sulfate-respiring bacteria as well as methanogens. Formation of acetylene-free environments in soils and sediments would also alter the function of nitrogenase from detoxification to nitrogen-fixation. The possibility of an acetylene-based anaerobic food chain in Jovian-type atmospheres is discussed. ?? 1988 Kluwer Academic Publishers.

  15. Oxy-acetylene driven laboratory scale shock tubes for studying blast wave effects.

    PubMed

    Courtney, Amy C; Andrusiv, Lubov P; Courtney, Michael W

    2012-04-01

    This paper describes the development and characterization of modular, oxy-acetylene driven laboratory scale shock tubes. Such tools are needed to produce realistic blast waves in a laboratory setting. The pressure-time profiles measured at 1 MHz using high-speed piezoelectric pressure sensors have relevant durations and show a true shock front and exponential decay characteristic of free-field blast waves. Descriptions are included for shock tube diameters of 27-79 mm. A range of peak pressures from 204 kPa to 1187 kPa (with 0.5-5.6% standard error of the mean) were produced by selection of the driver section diameter and distance from the shock tube opening. The peak pressures varied predictably with distance from the shock tube opening while maintaining both a true blast wave profile and relevant pulse duration for distances up to about one diameter from the shock tube opening. This shock tube design provides a more realistic blast profile than current compression-driven shock tubes, and it does not have a large jet effect. In addition, operation does not require specialized personnel or facilities like most blast-driven shock tubes, which reduces operating costs and effort and permits greater throughput and accessibility. It is expected to be useful in assessing the response of various sensors to shock wave loading; assessing the reflection, transmission, and absorption properties of candidate armor materials; assessing material properties at high rates of loading; assessing the response of biological materials to shock wave exposure; and providing a means to validate numerical models of the interaction of shock waves with structures. All of these activities have been difficult to pursue in a laboratory setting due in part to lack of appropriate means to produce a realistic blast loading profile. PMID:22559580

  16. Oxy-acetylene driven laboratory scale shock tubes for studying blast wave effects

    NASA Astrophysics Data System (ADS)

    Courtney, Amy C.; Andrusiv, Lubov P.; Courtney, Michael W.

    2012-04-01

    This paper describes the development and characterization of modular, oxy-acetylene driven laboratory scale shock tubes. Such tools are needed to produce realistic blast waves in a laboratory setting. The pressure-time profiles measured at 1 MHz using high-speed piezoelectric pressure sensors have relevant durations and show a true shock front and exponential decay characteristic of free-field blast waves. Descriptions are included for shock tube diameters of 27-79 mm. A range of peak pressures from 204 kPa to 1187 kPa (with 0.5-5.6% standard error of the mean) were produced by selection of the driver section diameter and distance from the shock tube opening. The peak pressures varied predictably with distance from the shock tube opening while maintaining both a true blast wave profile and relevant pulse duration for distances up to about one diameter from the shock tube opening. This shock tube design provides a more realistic blast profile than current compression-driven shock tubes, and it does not have a large jet effect. In addition, operation does not require specialized personnel or facilities like most blast-driven shock tubes, which reduces operating costs and effort and permits greater throughput and accessibility. It is expected to be useful in assessing the response of various sensors to shock wave loading; assessing the reflection, transmission, and absorption properties of candidate armor materials; assessing material properties at high rates of loading; assessing the response of biological materials to shock wave exposure; and providing a means to validate numerical models of the interaction of shock waves with structures. All of these activities have been difficult to pursue in a laboratory setting due in part to lack of appropriate means to produce a realistic blast loading profile.

  17. A systematic investigation of acetylene activation and hydracyanation of the activated acetylene on Aun (n = 3-10) clusters via density functional theory.

    PubMed

    Gautam, Seema; Sarkar, Abir De

    2016-05-18

    A systematic investigation of the selective catalytic conversion of poisonous HCN gas through hydracyanation of C2H2 activated on Au clusters, presented here for the first time, is of paramount importance from both scientific and technological perspectives. Hydracyanation of activated acetylene on an Au-cluster based catalyst leads to vinyl isocyanide (H2C[double bond, length as m-dash]CHNC) formation, a versatile chemical intermediate. Using density functional theory, bond activation of acetylene and selective catalytic hydracyanation of activated acetylene on small gold clusters Aun (n = 3-10) have been studied through a detailed analysis of the geometric and electronic structures. Different possible complexes of Aun-CHCH have been studied and two possible modes of adsorption of acetylene over the gold clusters, namely, the π- and di-σ modes, have been observed. The hydracyanation of the acetylene molecule is found to occur via the cleavage of one of acetylene triple bonds at the cost of formation of two Au-C bonds followed by the binding of HCN to the activated C[double bond, length as m-dash]C bond via nitrogen's lone pair. Preferential binding sites for HCN and C2H2 are analyzed through Fukui function calculations, frontier molecular orbital analysis and natural population charge distribution analysis. Based on adsorption energies, odd-sized Aun clusters are found to be significantly more favorable for C2H2 adsorption with the C-C bond stretching up to 1.31 Å with respect to the C-C triple bond length of 1.21 Å in the gas phase. The stretching frequency of adsorbed complexes, C2H2/Aun, (3460 cm(-1)), decreases notably relative to the frequency of the free acetylene molecule (7948 cm(-1)), which is a signature of the bond activation of the acetylene molecule over the Au clusters. The high adsorption energy of HCN on the Au9-C2H2 complex implies the considerable binding strength and activation of C2H2 and HCN on the Au9 clusters. Due to the importance of

  18. Effect of oxygen partial pressure on the magnetic properties of La2/3Sr1/3MnO3 films grown on SrTiO3 (1 1 1) substrates by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Prajapat, C. L.; Kalita, Parswajit; Sastry, P. U.; Singh, M. R.; Gupta, S. K.; Ravikumar, G.

    2014-09-01

    The influence of oxygen partial pressure on phase formation and magnetic properties of LSMO (La2/3Sr1/3MnO3) thin films deposited on STO (1 1 1) substrates by pulsed laser deposition was investigated. Phase formation and epitaxial growth were confirmed by X-ray diffraction. Good crystalline mosaic is observed for oxygen partial pressures ranging from 0.3 to 1.0 mbar. For each of the pressures, the lattice parameters were estimated assuming the lattice distortion is volume conserving. The Curie temperatures TC vs lattice strain relation thus obtained is comparable to the available data in literature. Variation in coercive field of the films can be accounted for by the variation in TC.

  19. Pore chemistry and size control in hybrid porous materials for acetylene capture from ethylene.

    PubMed

    Cui, Xili; Chen, Kaijie; Xing, Huabin; Yang, Qiwei; Krishna, Rajamani; Bao, Zongbi; Wu, Hui; Zhou, Wei; Dong, Xinglong; Han, Yu; Li, Bin; Ren, Qilong; Zaworotko, Michael J; Chen, Banglin

    2016-07-01

    The trade-off between physical adsorption capacity and selectivity of porous materials is a major barrier for efficient gas separation and purification through physisorption. We report control over pore chemistry and size in metal coordination networks with hexafluorosilicate and organic linkers for the purpose of preferential binding and orderly assembly of acetylene molecules through cooperative host-guest and/or guest-guest interactions. The specific binding sites for acetylene are validated by modeling and neutron powder diffraction studies. The energies associated with these binding interactions afford high adsorption capacity (2.1 millimoles per gram at 0.025 bar) and selectivity (39.7 to 44.8) for acetylene at ambient conditions. Their efficiency for the separation of acetylene/ethylene mixtures is demonstrated by experimental breakthrough curves (0.73 millimoles per gram from a 1/99 mixture). PMID:27198674

  20. Evaluation of Sorbents for Acetylene Separation in Atmosphere Revitalization Loop Closure

    NASA Technical Reports Server (NTRS)

    Abney, Morgan B.; Miller, Lee A.; Barton, Katherine

    2012-01-01

    State-of-the-art carbon dioxide reduction technology uses a Sabatier reactor to recover water from metabolic carbon dioxide. In order to maximize oxygen loop closure, a byproduct of the system, methane, must be reduced to recover hydrogen. NASA is currently exploring a microwave plasma methane pyrolysis system for this purpose. The resulting product stream of this technology includes unreacted methane, product hydrogen, and acetylene. The hydrogen and the small amount of unreacted methane resulting from the pyrolysis process can be returned to the Sabatier reactor thereby substantially improving the overall efficiency of the system. However, the acetylene is a waste product that must be removed from the pyrolysis product. Two materials have been identified as potential sorbents for acetylene removal: zeolite 4A, a commonly available commercial sorbent, and HKUST-1, a newly developed microporous metal. This paper provides an explanation of the rationale behind acetylene removal and the results of separation testing with both materials

  1. Evaluation of Sorbents for Acetylene Separation in Atmosphere Revitalization Loop Closure

    NASA Technical Reports Server (NTRS)

    Abney, Morgan B.; Miller, Lee A.; Barton, Katherine

    2011-01-01

    State-of-the-art carbon dioxide reduction technology uses a Sabatier reactor to recover water from metabolic carbon dioxide. In order to maximize oxygen loop closure, a byproduct of the system, methane, must be reduced to recover hydrogen. NASA is currently exploring a microwave plasma methane pyrolysis system for this purpose. The resulting product stream of this technology includes unreacted methane, product hydrogen, and acetylene. The hydrogen and the small amount of unreacted methane resulting from the pyrolysis process can be returned to the Sabatier reactor thereby substantially improving the overall efficiency of the system. However, the acetylene is a waste product that must be removed from the pyrolysis product. Two materials have been identified as potential sorbents for acetylene removal: zeolite 4A, a commonly available commercial sorbent, and HKUST-1, a newly developed microporous metal. This paper provides an explanation of the rationale behind acetylene removal and the results of separation testing with both materials.

  2. KISS: Kinetics and Structure of Superagglomerates Produced by Silane and Acetylene

    NASA Technical Reports Server (NTRS)

    Mulholland, G. W.; Yang, J. C.; Scott, J. H.; Sivithanu, Y.

    2001-01-01

    The objective of this study is to understand the process of gas phase agglomeration leading to superagglomerates and a gel-like structure for microgravity (0-g) silane and acetylene flames. Ultimately one would apply this understanding to predicting flame conditions that could lead to the gas phase production of an aero-gel. The approach is to burn acetylene and silane and to analyze the evolution of the soot and silica agglomerates. Acetylene is chosen because it has one of the highest soot volume fractions and there is evidence of super agglomerates being formed in laminar acetylene flames. Silane has the advantage that silica particles are the major combustion product resulting in a particle volume fraction a factor of ten greater than that for a carbonaceous smoke.

  3. Characterization of the Minimum Energy Paths and Energetics for the Reaction of Vinylidene with Acetylene

    NASA Technical Reports Server (NTRS)

    Walch, Stephen P.; Taylor, Peter R.

    1995-01-01

    The reaction of vinylidene (CH2C) with acetylene may be an initiating reaction in soot formation. We report minimum energy paths and accurate energetics for a pathway leading to vinyl-acetylene and for a number of isomers of C4H4. The calculations use complete active space self-consistent field (CASSCF) derivative methods to characterize the stationary points and internally contacted configuration interaction (ICCI) and/or coupled cluster singles and doubles with a perturbational estimate of triple excitations (CCSD(T)) to determine the energetics. We find an entrance channel barrier of about 5 kcal/mol for the addition of vinylidene to acetylene, but no barriers above reactants for the reaction pathway leading to vinyl-acetylene.

  4. Structure of the non-redox-active tungsten/[4Fe:4S] enzyme acetylene hydratase.

    PubMed

    Seiffert, Grazyna B; Ullmann, G Matthias; Messerschmidt, Albrecht; Schink, Bernhard; Kroneck, Peter M H; Einsle, Oliver

    2007-02-27

    The tungsten-iron-sulfur enzyme acetylene hydratase stands out from its class because it catalyzes a nonredox reaction, the hydration of acetylene to acetaldehyde. Sequence comparisons group the protein into the dimethyl sulfoxide reductase family, and it contains a bis-molybdopterin guanine dinucleotide-ligated tungsten atom and a cubane-type [4Fe:4S] cluster. The crystal structure of acetylene hydratase at 1.26 A now shows that the tungsten center binds a water molecule that is activated by an adjacent aspartate residue, enabling it to attack acetylene bound in a distinct, hydrophobic pocket. This mechanism requires a strong shift of pK(a) of the aspartate, caused by a nearby low-potential [4Fe:4S] cluster. To access this previously unrecognized W-Asp active site, the protein evolved a new substrate channel distant from where it is found in other molybdenum and tungsten enzymes. PMID:17360611

  5. A method for measuring brain partial pressure of oxygen in unanesthetized unrestrained subjects: the effect of acute and chronic hypoxia on brain tissue PO2

    PubMed Central

    Ortiz-Prado, E.; Natah, Siraj; Srinivasan, Sathyanarayanan; Dunn, Jeff F.

    2011-01-01

    The level of tissue oxygenation provides information related to the balance between oxygen delivery, oxygen utilization, tissue reactivity and morphology during physiological conditions. Tissue partial pressure of oxygen (PtO2) is influenced by the use of anesthesia or restraint. These factors may impact the absolute level of PtO2. In this study we present a novel fibre optic method to measure brain PtO2. This method can be used in unanesthetized, unrestrained animals, provides absolute values for PO2, has a stable calibration, does not consume oxygen and is MRI compatible. Brain PtO2 was studied during acute hypoxia, as well as before and after 28 days of high altitude acclimatization. A sensor was chronically implanted in the frontal cortex of 8 Wistar rats. It is comprised of a fiber optic probe with a tip containing material that fluoresces with an oxygen dependent lifetime. Brain PtO2 declines by 80% and 76% pre- and post-acclimatization respectively, when the fraction of inspired oxygen declines from 0.21 to 0.08. In addition, a linear relationship between brain PtO2 and inspired O2 levels was demonstrated r2=0.98 and r2=0.99 (pre- and post-acclimatization). Hypoxia acclimatization resulted in an increase in the overall brain PtO2 by approximately 35%. This paper demonstrates the use of a novel chronically implanted fibre optic based sensor for measuring absolute PtO2. It shows a very strong linear relationship in awake animals between inspired O2 and tissue O2, and shows that there is a proportional increase in PtO2 over a range of inspired values after exposure to chronic hypoxia. PMID:20817029

  6. Overreactivity of the psyche or the soma? Interindividual associations between psychosomatic symptoms, anxiety, heart rate, and end-tidal partial carbon dioxide pressure.

    PubMed

    Wientjes, C J; Grossman, P

    1994-01-01

    Current research has all but refuted previous suggestions about the role of hyperventilation as a proximal, common cause of psychosomatic symptoms. As an alternative, it has been proposed that the experience of psychosomatic symptoms is primarily associated with psychological mechanisms, i.e., with enhanced tendencies of distressed individuals to focus their attention on bodily sensations and to evaluate these in a catastrophic manner. Although this hypothesis has received considerable empirical support, physiological influences on symptom reporting have not, as yet, been fully explored. In this study, contributions of psychological and physiological factors were studied among a group of 83 normal healthy male subjects by an assessment of the interindividual relationships between symptom experience in daily life, situational and dispositional anxiety, baseline end-tidal partial carbon dioxide pressure (PCO2), and heart rate. Trait anxiety and end-tidal PCO2 each contributed separately to the prediction of the psychosomatic symptom score. Trait anxiety explained nearly one third of the symptom variance, and an additional 4% was explained by PCO2. Psychological symptoms were more strongly associated with anxiety and somatic symptoms, more strongly with PCO2. Heart rate only tended to be correlated with symptom reporting. Analysis of covariance among subgroups of extreme-symptom reporters supported the correlational findings by demonstrating that the association between hyperventilation and symptom reporting remained intact when psychological influences were factored out. The findings suggest that reports of psychosomatic symptoms represent two distinct components: one that is primarily psychological (and is unrelated to physiological factors) and a second that reflects objective variance in physiological functioning. The influence of the first component is probably greater than that of the second. PMID:7871109

  7. [The tissue oxygen partial pressure in organs of hens in the second half of embryogenesis and in the first days after hatching].

    PubMed

    Belichenko, V M; Turganbaeva, A S; Khodyrev, E V; Kisliakova, L P; Kisliakov, Iu Ia; Shoshenko, K A

    2014-01-01

    The aim of the study was measure the development chick tissue partial pressure of oxygen (pO2) in the brain cerebral hemispheres, liver, M. pectoralis, M. gastrocnemius, and to estimate the correlation of this index with our previously measured values (laser-Doppler flowmetry) volume blood flow (BF) in these organs. We studied 10-, 15-, and 19-day embryos and 4-day chickens thatwere anesthetized with urethane. pO2 measurements were made in thesurface layers of organs by the membrane amperometric Clark-type O2-electrode with a diameter of about 50 microm of the cathode placed in the center of the sensor with an outer diameter of 3.4 mm. Disclosed noticeable distinction of both the organ tissue pO2 values, and the dynamics of their changes duringthe study period. The most important of them: (1) the lowest pO2 (and BF) is observed in the brain and particularly in the liver of 10-day embryos; (2) in the subsequent period of embryogenesis pO2 in the brain increases 1.9 times (rising and BF) in M. pectoralis it falls by 1.7 times and in the liver.and in M. gastrocnemius changes little wherein the BF in both liver and muscles is not changed, (3) after hatching pO2 in the liver and M. petoralis fold increased (also increasing and BF), and in the brain and M. gastrocnemius, despite the increase BF (greater in the niuscle) did not significant change. In the analysis ofthedata are considered two possible mechanisms of change of tissue pO2 in the developing organs of chickens, one is due to the peculiarities of intracardiac blood flows; and the other is related to thesingularity of the oxyhemoglobin dissociation in the blood capillary bed of organ, determined by the specifics of its oxidative metabolism. PMID:25752150

  8. Oxidation Behavior and Cracking Susceptibility of Ni-Cr Alloys in Dry Steam and Inert Gas under Extremely-Low Oxygen Partial Pressure

    NASA Astrophysics Data System (ADS)

    Abe, Hiroshi; Kenmoku, Yasuhiro; Endo, Takayuki; Miyazaki, Takamichi; Watanabe, Yutaka

    In order to investigate oxidation behavior and cracking susceptibility of the Ni-Cr alloys under extremely-low oxygen partial pressure, three Ni-Cr alloys (Ni-14Cr, Ni-22Cr and Ni-30Cr) were used as plate specimen and reverse U-bend specimen for oxidation experiments for 750 hours at 400 °C in two kinds of gas system (inert gas and dry steam) under various oxygen potential (Ni stable, Ni/NiO equilibrium and NiO stable). The Ni-Cr alloys cracked along grain boundary both in inert gas system (with trace O2, without H2O) and in hydrogenated steam. In the inert gas system, the cracking susceptibility was confirmed in near NiO stable condition. On the other hand, no crack was found in near Ni stable condition. In the dry steam system, the cracking susceptibility was confirmed in near Ni/NiO equilibrium. In contrast, no crack was found in near NiO stable condition. The cracking susceptibility was confirmed in near Ni/NiO equilibrium in hydrogenated steam as contrasted with higher oxygen potential in inert gas system. This result shows that potential range for the cracking susceptibility seemed to be different between the two kinds of gas system. Cracking severity was highest for Ni-14Cr and lowest for Ni-30Cr both in inert gas and steam; however, even Ni-30Cr was not immune to intergranular cracking in steam near Ni/NiO equilibrium.

  9. Correlation between the Carbon Isotope Discrimination in Leaf Starch and Sugars of C3 Plants and the Ratio of Intercellular and Atmospheric Partial Pressures of Carbon Dioxide

    PubMed Central

    Brugnoli, Enrico; Hubick, Kerry T.; von Caemmerer, Susanne; Wong, Suan Chin; Farquhar, Graham D.

    1988-01-01

    Carbon isotope discrimination (Δ) was analyzed in leaf starch and soluble sugars, which represent most of the recently fixed carbon. Plants of three C3 species (Populus nigra L. × P. deltoides Marsh., Gossypium hirsutum L. and Phaseolus vulgaris L.) were kept in the dark for 24 hours to decrease contents of starch and sugar in leaves. Then gas exchange measurements were made with constant conditions for 8 hours, and subsequently starch and soluble sugars were extracted for analysis of carbon isotope composition. The ratio of intercellular, pi, and atmospheric, pa, partial pressures of CO2, was calculated from gas exchange measurements, integrated over time and weighted by assimilation rate, for comparison with the carbon isotope ratios in soluble sugars and starch. Carbon isotope discrimination in soluble sugars correlated strongly (r = 0.93) with pi/pa in all species, as did Δ in leaf starch (r = 0.84). Starch was found to contain significantly more 13C than soluble sugar, and possible explanations are discussed. The strong correlation found between Δ and pi/pa suggests that carbon isotope analysis in leaf starch and soluble sugars may be used for monitoring, indirectly, the average of pi/pa weighted by CO2 assimilation rate, over a day. Because pi/pa has a negative correlation with transpiration efficiency (mol CO2/mol H2O) of isolated plants, Δ in starch and sugars may be used to predict differences in this efficiency. This new method may be useful in ecophysiological studies and in selection for improved transpiration efficiency in breeding programs for C3 species. PMID:16666476

  10. Adsorption of Acetylene on a Pd-Pb Bimetallic Surface — a Theoretical Study

    NASA Astrophysics Data System (ADS)

    Ferullo, R. M.; Touroude, R.; Castellani, N. J.

    A semiempirical molecular orbital study of acetylene adsorption over Pd(111) and Pd3Pb(111) has been performed. A strong negative effect of Pb atoms on Pd chemisorptive strength was observed in the alloy. This behavior is related to a lower hybridization between acetylene π* and Pd orbitals when this mental interacts with Pb. Moreover this negative effect of Pb is of a strong local character.

  11. Tunable thermal conductivity in carbon allotrope sheets: Role of acetylenic linkages

    NASA Astrophysics Data System (ADS)

    Wang, Jian; Zhang, Ai-Juan; Tang, Yuansheng

    2015-11-01

    The versatility of carbon in forming the hybridization states allows one to design more carbon allotropes with various fascinating properties by replacing some aromatic bonds with acetylenic linkages. We investigate thermal conductivities of carbon allotrope sheets with different configurations by nonequilibrium molecular dynamic simulations. It is found that the acetylenic linkages not only considerably reduce thermal conductivity but also can effectively tune thermal conductivity through the various bonding methods. We suggest that the structure of stripes of benzene rings transversely bonded with the acetylenic linkages can potentially be one of high thermoelectric materials. We find that the reason for the manipulation of thermal conductivity by the acetylenic linkage can be attributed to the strong localizations of phonon modes that result in the reduced phonon group velocity and the shortened lifetime of phonons. It is also observed that thermal conductivity of graphyne sheet shows a power-law divergence with respect to the length. We propose a new approach to manipulating thermal conductivities in the carbon allotropes through the assembling of acetylenic linkages. Our findings conclusively clarify the role of acetylenic linkages in thermal transport and offer some valuable insights into the exploration of new thermoelectric materials as well as the experimental control of heat flux.

  12. A porous metal-organic framework with ultrahigh acetylene uptake capacity under ambient conditions.

    PubMed

    Pang, Jiandong; Jiang, Feilong; Wu, Mingyan; Liu, Caiping; Su, Kongzhao; Lu, Weigang; Yuan, Daqiang; Hong, Maochun

    2015-01-01

    Acetylene, an important petrochemical raw material, is very difficult to store safely under compression because of its highly explosive nature. Here we present a porous metal-organic framework named FJI-H8, with both suitable pore space and rich open metal sites, for efficient storage of acetylene under ambient conditions. Compared with existing reports, FJI-H8 shows a record-high gravimetric acetylene uptake of 224 cm(3) (STP) g(-1) and the second-highest volumetric uptake of 196 cm(3) (STP) cm(-3) at 295 K and 1 atm. Increasing the storage temperature to 308 K has only a small effect on its acetylene storage capacity (∼200 cm(3) (STP) g(-1)). Furthermore, FJI-H8 exhibits an excellent repeatability with only 3.8% loss of its acetylene storage capacity after five cycles of adsorption-desorption tests. Grand canonical Monte Carlo simulation reveals that not only open metal sites but also the suitable pore space and geometry play key roles in its remarkable acetylene uptake. PMID:26123775

  13. A porous metal-organic framework with ultrahigh acetylene uptake capacity under ambient conditions

    PubMed Central

    Pang, Jiandong; Jiang, Feilong; Wu, Mingyan; Liu, Caiping; Su, Kongzhao; Lu, Weigang; Yuan, Daqiang; Hong, Maochun

    2015-01-01

    Acetylene, an important petrochemical raw material, is very difficult to store safely under compression because of its highly explosive nature. Here we present a porous metal-organic framework named FJI-H8, with both suitable pore space and rich open metal sites, for efficient storage of acetylene under ambient conditions. Compared with existing reports, FJI-H8 shows a record-high gravimetric acetylene uptake of 224 cm3 (STP) g−1 and the second-highest volumetric uptake of 196 cm3 (STP) cm−3 at 295 K and 1 atm. Increasing the storage temperature to 308 K has only a small effect on its acetylene storage capacity (∼200 cm3 (STP) g−1). Furthermore, FJI-H8 exhibits an excellent repeatability with only 3.8% loss of its acetylene storage capacity after five cycles of adsorption–desorption tests. Grand canonical Monte Carlo simulation reveals that not only open metal sites but also the suitable pore space and geometry play key roles in its remarkable acetylene uptake. PMID:26123775

  14. Mechanism-based inactivation of benzo(a)pyrene hydroxylase by aryl acetylenes and aryl olefins

    SciTech Connect

    Gan, L.S.; Lu, J.Y.L.; Alworth, W.L.

    1986-05-01

    A series of aryl acetylenes and aryl olefins have been examined as substrates and inhibitors of cytochrome P-450 dependent monooxgenases in liver microsomes from 5,6-benzoflavone or phenobarbital pretreated rats. 1-Ethynylpyrene, 3-ethynylperylene, 2-ethynylfluorene, methyl 1-pyrenyl acetylene, cis- and trans-1-(2-bromovinyl)pyrene, and 1-allylpyrene serve as mechanism-based irreversible inactivators (suicide inhibitors) of benzo(a)pyrene hydroxylase, while 1-vinylpyrene and phenyl 1-pyrenyl acetylene do not cause a detectable suicide inhibition of benzo(a)pyrene hydroxylase. The mechanism-based loss of benzo(a)pyrene hydroxylase caused by the aryl acetylenes is not accompanied by a corresponding loss of the P-450 content of the microsomes (suicide destruction). The suicide inhibition by these aryl acetylenes therefore does not involve covalent binding to the heme moiety of the monooxygenase. Nevertheless, in the presence of NADPH, /sup 3/H-labeled 1-ethynylpyrene becomes covalently attached to the cytochrome P-450 protein; the measured stoichiometry of binding is one 1-ethynylpyrene per P-450 heme unit. The authors conclude that the inhibition of benzo(a)pyrene hydroxylase produced by 1-ethynylpyrene may be related to the mechanism of suicide inhibition of P-450 activity by chloramphenicol rather than the mechanism of suicide destruction of P-450 previously described for acetylene and propyne.

  15. Two-wavelength interferometer based on sinusoidal phase modulation with an acetylene stabilized laser and a second harmonic generation.

    PubMed

    Kawata, Yoshiyuki; Hyashi, Kyohei; Aoto, Tomohiro

    2015-06-15

    A two-wavelength interferometer (TWI) based on a sinusoidal-phase-modulation method with an acetylene stabilized laser and a second harmonic generation (SHG) was developed. The periodic non-linearity error for the TWI was estimated to be ± 0.1 µm at a dead path of 0.32 m. A long-term measurement showed that the TWI stability was ± 3 × 10(-7) at a dead path of 1.00 m for 12 hours with an ambient pressure variation of 3 hPa under controlled conditions of ambient temperature and humidity. Finally, we confirmed that the TWI has substantially better stability than a single-wavelength interferometer by comparing both interferometers with large temporal and spatial temperature variations. PMID:26193576

  16. Wavelength modulation spectroscopy at 1530.32 nm for measurements of acetylene based on Fabry-Perot tunable filter

    NASA Astrophysics Data System (ADS)

    Yun-Long, Li; Bing-Chu, Yang; Xue-Mei, Xu

    2016-02-01

    Sensitive detection of acetylene (C2H2) is performed by absorption spectroscopy and wavelength modulation spectroscopy (WMS) based on Fiber Fabry-Perot tunable filter (FFP-TF) at 1530.32 nm. After being calibrated by Fiber Bragg Grating (FBG), FFP-TF is frequency-multiplexed and modulated at 20 Hz and 2.5 kHz respectively to achieve wavelength modulation. The linearity with 0.9907 fitting coefficient is obtained by measuring different concentrations in a 100 ppmv-400 ppmv range. Furthermore, the stability of the system is analyzed by detecting 50 ppmv and 100 ppmv standard gases for 2 h under room temperature and ambient pressure conditions respectively. The precision of 11 ppmv is achieved by calculating the standard deviation. Therefore, the measuring system of C2H2 detection can be applied in practical applications. Project supported by the National Natural Science Foundation of China (Grant Nos. 61172047 and 61071025).

  17. ABSORPTION CROSS SECTION OF GASEOUS ACETYLENE AT 85 K IN THE WAVELENGTH RANGE 110-155 nm

    SciTech Connect

    Cheng, Bing-Ming; Chen, Hui-Fen; Lu, Hsiao-Chi; Chen, Hong-Kai; Alam, M. S.; Chou, Sheng-Lung; Lin, Meng-Yeh

    2011-09-01

    Absorption spectra and absorption cross sections of gaseous acetylene, C{sub 2}H{sub 2}, at 298 and 85 K were measured in the wavelength range 110-155 nm with a slit-jet system coupled to a synchrotron as a source of vacuum ultraviolet light. Using published spectral parameters of C{sub 2}H{sub 2}, we simulated the absorption profile for the Rydberg transition to state 4R{sub 0} in the range 124.6-125.1 nm, according to which the temperature of the jet-expanded sample at stagnation pressure 200 Torr is 85 {+-} 5 K. Our cross sections of C{sub 2}H{sub 2} are applicable for determining properties sensitive to temperature for diagnostic work on Saturn and Titan.

  18. Discovery, Development, and Commercialization of Gold Catalysts for Acetylene Hydrochlorination.

    PubMed

    Johnston, Peter; Carthey, Nicholas; Hutchings, Graham J

    2015-11-25

    Vinyl chloride monomer (VCM) is a major chemical intermediate for the manufacture of polyvinyl chloride (PVC), which is the third most important polymer in use today. Hydrochlorination of acetylene is a major route for the production of vinyl chloride, since production of the monomer is based in regions of the world where coal is abundant. Until now, mercuric chloride supported on carbon is used as the catalyst in the commercial process, and this exhibits severe problems associated with catalyst lifetime and mercury loss. It has been known for over 30 years that gold is a superior catalyst, but it is only now that it is being commercialized. In this Perspective we discuss the use and disadvantages of the mercury catalyst and the advent of the gold catalysts for this important reaction. The nature of the active site and the possible reaction mechanism are discussed. Recent advances in the design and preparation of active gold catalysts containing ultralow levels of gold are described. In the final part, a view to the future of this chemistry will be discussed as well as the possible avenues for the commercial potential of gold catalysis. PMID:26529366

  19. An improved processible acetylene-terminated polyimide for composites

    NASA Technical Reports Server (NTRS)

    Landis, A. L.; Naselow, A. B.

    1985-01-01

    The newest member of a family of thermosetting acetylene-substituted polyimide oligomers is HR600P. This oligomer is the isoimide version of the oligomer known as HR600P and Thermid 600. Although both types of material yield the same heat resistant end products after cure, HR600P has much superior processing characteristics. This attributed to its lower melting temperature (160 + or - 10 C, 320 + or - 20 F) in contrast to 202 C (396 F) for Thermid MC-600, its longer gel time at its processing temperature (16 to 30 minutes bvs 3 minutes), and its excellent solubility in low boiling solvents such as tetrahydrofuran, glymes, or 4:1 methyl ethyl ketone/toluene mixtures. These advantages provide more acceptable coating and impregnation procedures, allow for more complete removal at lower temperatures, provide a longer pot life or working time, and allow composite structure fabrication in conventional autoclaves used for epoxy composite curing. The excellent processing characteristics of HR600P allow its use in large area laminated structures, structural composites, and molding compositions.

  20. Acetylene fermentation: An Earth-based analog of biological carbon cycling on Titan

    NASA Astrophysics Data System (ADS)

    Miller, L. G.; Baesman, S. M.; Hoeft, S. E.; Kirshtein, J.; Wolf, K.; Voytek, M. A.; Oremland, R. S.

    2009-12-01

    Acetylene (C2H2) is present in part per million quantities in the atmosphere of Titan; conceivably as an intermediate product of methane photolysis. Currently, Earth’s atmosphere contains only trace amounts of C2H2 (~40 pptv), however higher concentrations likely prevailed during the Hadean and early Archean eons (4.5 - 3.5 Ga). We isolated C2H2-fermenting microbes from various aquatic and sedimentary environments. Acetylene fermentation proceeds via acetylene hydratase (AH) through acetaldehyde, which dismutates to ethanol and acetate, and if oxidants are present (e.g., sulfate) eventually to CO2. Thus, the remnants of a C2H2 cycle exists today on Earth but may also occur on Titan and/or Enceladus, both being planetary bodies hypothesized to have liquid water underlying their frozen surfaces. We developed a molecular method for AH by designing PCR primers to target the functional gene in Pelobacter acetylenicus. We used this method to scan new environments for the presence of AH and we employed DNA sequencing of the 16S rRNA gene in order to positively identify pelobacters in environmental samples. Acetylene fermentation was documented in five diverse salt-, fresh-, and ground-water sites. Pelobacter was identified as the genus responsible for acetylene fermentation in some, but not all, of these sites. Successful probing for AH preceded the discovery of acetylene consumption in a contaminated groundwater site, demonstrating the utility of functional gene probing. A pure culture of a C2H2-fermenting pelobacter was obtained from an intertidal mudflat. We also obtained an enrichment culture (co-cultured with a sulfate reducer) from freshwater lake sediments, but neither was pelobacter nor AH detected in this sample, suggesting that an alternative pathway may be involved here. Slurry experiments using these lake sediments either with or without added C2H2 or sulfate showed that sulfate reduction and acetylene fermentation were independent processes. In general, the

  1. Measurement of cardiac output during exercise by open-circuit acetylene uptake.

    PubMed

    Barker, R C; Hopkins, S R; Kellogg, N; Olfert, I M; Brutsaert, T D; Gavin, T P; Entin, P L; Rice, A J; Wagner, P D

    1999-10-01

    Noninvasive measurement of cardiac output (QT) is problematic during heavy exercise. We report a new approach that avoids unpleasant rebreathing and resultant changes in alveolar PO(2) or PCO(2) by measuring short-term acetylene (C(2)H(2)) uptake by an open-circuit technique, with application of mass balance for the calculation of QT. The method assumes that alveolar and arterial C(2)H(2) pressures are the same, and we account for C(2)H(2) recirculation by extrapolating end-tidal C(2)H(2) back to breath 1 of the maneuver. We correct for incomplete gas mixing by using He in the inspired mixture. The maneuver involves switching the subject to air containing trace amounts of C(2)H(2) and He; ventilation and pressures of He, C(2)H(2), and CO(2) are measured continuously (the latter by mass spectrometer) for 20-25 breaths. Data from three subjects for whom multiple Fick O(2) measurements of QT were available showed that measurement of QT by the Fick method and by the C(2)H(2) technique was statistically similar from rest to 90% of maximal O(2) consumption (VO(2 max)). Data from 12 active women and 12 elite male athletes at rest and 90% of VO(2 max) fell on a single linear relationship, with O(2) consumption (VO(2)) predicting QT values of 9.13, 15.9, 22.6, and 29.4 l/min at VO(2) of 1, 2, 3, and 4 l/min. Mixed venous PO(2) predicted from C(2)H(2)-determined QT, measured VO(2), and arterial O(2) concentration was approximately 20-25 Torr at 90% of VO(2 max) during air breathing and 10-15 Torr during 13% O(2) breathing. This modification of previous gas uptake methods, to avoid rebreathing, produces reasonable data from rest to heavy exercise in normal subjects. PMID:10517785

  2. The Ratio of Partial Pressure Arterial Oxygen and Fraction of Inspired Oxygen 1 Day After Acute Respiratory Distress Syndrome Onset Can Predict the Outcomes of Involving Patients.

    PubMed

    Lai, Chih-Cheng; Sung, Mei-I; Liu, Hsiao-Hua; Chen, Chin-Ming; Chiang, Shyh-Ren; Liu, Wei-Lun; Chao, Chien-Ming; Ho, Chung-Han; Weng, Shih-Feng; Hsing, Shu-Chen; Cheng, Kuo-Chen

    2016-04-01

    The initial hypoxemic level of acute respiratory distress syndrome (ARDS) defined according to Berlin definition might not be the optimal predictor for prognosis. We aimed to determine the predictive validity of the stabilized ratio of partial pressure arterial oxygen and fraction of inspired oxygen (PaO2/FiO2 ratio) following standard ventilator setting in the prognosis of patients with ARDS.This prospective observational study was conducted in a single tertiary medical center in Taiwan and compared the stabilized PaO2/FiO2 ratio (Day 1) following standard ventilator settings and the PaO2/FiO2 ratio on the day patients met ARDS Berlin criteria (Day 0). Patients admitted to intensive care units and in accordance with the Berlin criteria for ARDS were collected between December 1, 2012 and May 31, 2015. Main outcome was 28-day mortality. Arterial blood gas and ventilator setting on Days 0 and 1 were obtained.A total of 238 patients met the Berlin criteria for ARDS were enrolled, and they were classified as mild (n = 50), moderate (n = 125), and severe (n = 63) ARDS, respectively. Twelve (5%) patients who originally were classified as ARDS did not continually meet the Berlin definition, and a total of 134 (56%) patients had the changes regarding the severity of ARDS from Day 0 to Day 1. The 28-day mortality rate was 49.1%, and multivariate analysis identified age, PaO2/FiO2 on Day 1, number of organ failures, and positive fluid balance within 5 days as significant risk factors of death. Moreover, the area under receiver-operating curve for mortality prediction using PaO2/FiO2 on Day 1 was significant higher than that on Day 0 (P = 0.016).PaO2/FiO2 ratio on Day 1 after applying mechanical ventilator is a better predictor of outcomes in patients with ARDS than those on Day 0. PMID:27057912

  3. Temporal changes in surface partial pressure of carbon dioxide and carbonate saturation state in the eastern equatorial Indian Ocean during the 1962-2012 period

    NASA Astrophysics Data System (ADS)

    Xue, L.; Yu, W.; Wang, H.; Jiang, L.-Q.; Feng, L.; Gao, L.; Li, K.; Li, Z.; Wei, Q.; Ning, C.

    2014-11-01

    Information on changes in the oceanic carbon dioxide (CO2) concentration and air-sea CO2 flux as well as on ocean acidification in the Indian Ocean is very limited. In this study, temporal changes of the inorganic carbon system in the eastern equatorial Indian Ocean (EIO, 5° N-5° S, 90-95° E) are examined using partial pressure of carbon dioxide (pCO2) data collected in May 2012, historical pCO2 data since 1962, and total alkalinity (TA) data calculated from salinity. Results show that sea surface pCO2 in the equatorial belt (2° N-2° S, 90-95° E) increased from ∼307 μatm in April 1963 to ∼373 μatm in May 1999, ∼381 μatm in April 2007, and ∼385 μatm in May 2012. The mean rate of pCO2 increase in this area (∼1.56 μatm yr-1) was close to that in the atmosphere (∼1.46 μatm yr-1). Despite the steady pCO2 increase in this region, no significant change in air-sea CO2 fluxes was detected during this period. Ocean acidification as indicated by pH and saturation states for carbonate minerals has indeed taken place in this region. Surface water pH (total hydrogen scale) and saturation state for aragonite (Ωarag), calculated from pCO2 and TA, decreased significantly at rates of -0.0016 ± 0.0001 and -0.0095 ± 0.0005 yr-1, respectively. The respective contributions of temperature, salinity, TA, and dissolved inorganic carbon (DIC) to the increase in surface pCO2 and the decreases in pH and Ωarag are quantified. We find that the increase in DIC dominated these changes, while contributions from temperature, salinity, and TA were insignificant. The increase in DIC was most likely associated with the increasing atmospheric CO2 concentration, and the transport of accumulated anthropogenic CO2 from a CO2 sink region via basin-scale ocean circulations. These two processes may combine to drive oceanic DIC to follow atmospheric CO2 increase.

  4. Non-invasive assessment of fluid responsiveness by changes in partial end-tidal CO2 pressure during a passive leg-raising maneuver

    PubMed Central

    2012-01-01

    Background The passive leg-raising (PLR) maneuver provides a dynamic assessment of fluid responsiveness inducing a reversible increase in cardiac preload. Since its effects are sudden and transitory, a continuous cardiac output (CO) monitoring is required to appropriately assess the hemodynamic response of PLR. On the other hand, changes in partial end-tidal CO2 pressure (PETCO2) have been demonstrated to be tightly correlated with changes in CO during constant ventilation and stable tissue CO2 production (VCO2). In this study we tested the hypothesis that, assuming a constant VCO2 and under fixed ventilation, PETCO2 can track changes in CO induced by PLR and can be used to predict fluid responsiveness. Methods Thirty-seven mechanically ventilated patients with acute circulatory failure were monitored with the CardioQ-ODM esophageal Doppler. A 2-minutes PLR maneuver was performed. Fluid responsiveness was defined according to CO increase (responders ≥ 15%) after volume expansion. Results PLR-induced increases in CO and PETCO2 were strongly correlated (R2 = 0.79; P < 0.0001). The areas under the receiver-operating characteristics (ROC) curve for a PLR-induced increase in CO and PETCO2 (0.97 ± 0.03 SE; CI 95%: 0.85 to 0.99 and 0.94 ± 0.04 SE; CI 95%: 0.82 to 0.99; respectively) were not significantly different. An increase ≥ 5% in PETCO2 or ≥ 12% in CO during PLR predicted fluid responsiveness with a sensitivity of 90.5% (95% CI: 69.9 to 98.8%) and 95.2% (95% CI: 76.2 to 99.9%), respectively, and a specificity of 93.7% (95% CI: 69.8 to 99.8%). Conclusion Induced changes in PETCO2 during a PLR maneuver could be used to track changes in CO for prediction of fluid responsiveness in mechanically ventilated patients with acute circulatory failure, under fixed minute ventilation and assuming a constant tissue CO2 production. PMID:22449292

  5. The Role of Oxygen Partial Pressure in Controlling the Phase Composition of La1- x Sr x Co y Fe1- y O3- δ Oxygen Transport Membranes Manufactured by Means of Plasma Spray-Physical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Marcano, D.; Mauer, G.; Sohn, Y. J.; Vaßen, R.; Garcia-Fayos, J.; Serra, J. M.

    2016-04-01

    La0.58Sr0.4Co0.2Fe0.8O3 - δ (LSCF) deposited on a metallic porous support by plasma spray-physical vapor deposition is a promising candidate for oxygen-permeation membranes. Ionic transport properties are regarded to depend on the fraction of perovskite phase present in the membrane. However, during processing, the LSCF powder decomposes into perovskite and secondary phases. In order to improve the ionic transport properties of the membranes, spraying was carried out at different oxygen partial pressures p(O2). It was found that coatings deposited at lower and higher oxygen partial pressures consist of 70% cubic/26% rhombohedral and 61% cubic/35% rhombohedral perovskite phases, respectively. During annealing, the formation of non-perovskite phases is driven by oxygen non-stoichiometry. The amount of oxygen added during spraying can be used to increase the perovskite phase fraction and suppress the formation of non-perovskite phases.

  6. Infrared Spectra and Optical Constants of Acetylene and Ethane Ices

    NASA Astrophysics Data System (ADS)

    Moore, Marla H.; Ferrante, R. F.; Hudson, R. L.; Moore, W. J.

    2012-10-01

    Hydrocarbon-containing ices have characteristic absorption bands in both the mid- and near-infrared spectral regions, yet accurate optical constants are not available for most of these molecules. Ices with a hydrocarbon component have been identified on several TNOs (1) and the presence of volatiles, such as hydrocarbons, is inferred for intermediate or large TNOs based on sublimation models (2, 3). In our laboratory we recently have undertaken low-temperature spectroscopic studies of C2 hydrocarbons. We report IR spectra for acetylene (C2H2) and ethane (C2H6) ice in both the amorphous and crystalline phases at multiple temperatures. We include measurements of the refractive index at 670 nm for both the amorphous and crystalline phases of each ice. The optical constants, the real (n) and imaginary (k) components of the complex index of refraction, were determined from 7000 - 400 cm-1 (1.4 - 25 microns) at multiple temperatures using a Kramers-Kronig analysis. A goal of the present work is to provide a data base of optical constants of C2 molecules similar to that of Hudgins et al. (4) and Moore et al. (5). These values, as well as our calculated individual band strengths, will have great practical importance for the ongoing analysis of TNO spectra. (1) Brown, M.E. et al., Astron J., 133, 284, 2007. (2) Delsanti, A. et al., A&A, 52, A40, 2010. (3) Schaller, E. L. & Brown, M. E., ApJ, 659, L61, 2007. (4) Hudgins, D. M. et al., ApJS, 86, 713, 1993. (5) Moore, M. H. et al., ApJS, 191, 96, 2010. This work is supported by NASA’s Planetary Atmospheres, Outer Planets, and Cassini Data Analysis programs, and The Goddard Center for Astrobiology.

  7. Acetylene fuels reductive dechlorination of TCE by Dehalococcoides/Pelobacter-containing microbial consortia

    NASA Astrophysics Data System (ADS)

    Oremland, R. S.; Mao, X.; Mahandra, C.; Baesman, S. M.; Gushgari, S.; Alvarez-Cohen, L.; Liu, T.

    2015-12-01

    Groundwater contamination by trichloroethene (TCE) poses a threat to health and leads to the generation of vinyl chloride (VC), a carcinogen. Dehalococcoides mccartyi is the only bacterium that can completely dechlorinate TCE to ethene (C2H4). Acetylene (C2H2) occurs in TCE-contaminated sites as a consequence of chemical degradation of TCE. Yet acetylene inhibits a variety of microbial processes including methanogesis and reductive dechlorination. Pelobacter acetylenicus and related species can metabolize acetylene via acetylene hydratase and acetaldehyde dismutatse thereby generating acetate and H2 as endproducts, which could serve as electron donor and carbon source for growth of D. mccartyi. We found that 1mM acetylene (aqueous) inhibits growth of D. mccartyi strain 195 on 0.3 mM TCE, but that the inhibition was removed after 12 days with the addition of an acetylene-utilizing isolate from San Francisco Bay, Pelobacter strain SFB93. TCE did not inhibit the growth of this Pelobacter at the concentrations tested (0.1-0.5 mM) and TCE was not consumed by strain SFB93. Co-cultures of strain 195 with strain SFB93 at 5% inoculation were established in 120 mL serum bottles containing 40 mL defined medium. TCE was supplied at a liquid concentration of 0.1 mM, with 0.1 mM acetylene and N2/CO2 (90:10 v/v) headspace at 34 °C. Co-cultures were subsequently transferred (5% vol/vol inoculation) to generate subcultures after 20 μmol TCE was reduced to VC and 36 μmol acetylene was depleted. Aqueous H2 ranged from 114 to 217 nM during TCE-dechlorination, and the cell yield of strain 195 was 3.7 ±0.3 × 107 cells μmol-1 Cl- released. In a D. mccartyi-containing enrichment culture (ANAS) under the same conditions as above, it was found that inhibition of dechlorination by acetylene was reversed after 19 days by adding SFB93. Thus we showed that a co-culture of Pelobacter SFB93 and D. mccartyi 195 could be maintained with C2H2 as the electron donor and carbon source while TCE

  8. Acetylene Fermentation: Relevance to Primordial Biogeochemistry and the Search for Life in the Outer Solar System

    NASA Astrophysics Data System (ADS)

    Oremland, R. S.; Baesman, S. M.; Miller, L. G.

    2013-12-01

    Acetylene is a highly reactive component of planet(oid)s with anoxic, methane-rich atmospheres, such as Jupiter, Saturn, Titan, and perhaps the primordial Earth. Included in this group is Enceladus, although it is not clear if the acetylene detected within its jets by Cassini was formed by photolysis of methane, from thermo-catalysis of organic matter in the orb's interior, or a fragmentation artifact of the mass spectrum of a larger hydrocarbon. Acetylene inhibits many microbial processes (e.g., methanogenesis, methane oxidation, hydrogen metabolism, denitrification) yet a number of anaerobes can use it as a carbon and energy source to support growth. The best studied is Pelobacter acetylenicus, which carries out a two-step reaction involving the enzymes acetylene hydratase and acetaldehyde dismutase. The former, a low potential W-containing enzyme, forms acetaldehyde while the latter produces ethanol and acetate. Metabolism of acetylene by mixed microbial communities (sediments and/or enrichment cultures) produces these intermediates, and when coupled with sulfate-reduction or methanogenesis respectively forms CO2 or an equal mixtures of CO2 plus CH4. It is not inconceivable that such an anaerobic, microbial food chain could exist in the waters beneath the ice cap of Enceladus, Titan, or even in the mesothermal atmospheric regions of the gas giants. Detection of the identified intermediate products of acetylene fermentation, namely acetaldehyde, ethanol, acetate and formate in the atmospheres of these planet(oid)s would constitute evidence for a microbial life signature. This evidence would be strongly reinforced if a stable carbon isotope fractionation was identified as well, whereby the products of acetylene fermentation were enriched in 12C relative to 13C (i.e., had a lighter δ13C signal) when compared to that of the starting acetylene. The most practical target to test this hypothesis would be Enceladus (if the detected acetylene is shown to be a real

  9. Ionization of large homogeneous and heterogeneous clusters generated in acetylene-Ar expansions: Cluster ion polymerization

    SciTech Connect

    Kocisek, J.; Lengyel, J.; Farnik, M.

    2013-03-28

    Pure acetylene and mixed Ar-acetylene clusters are formed in supersonic expansions of acetylene/argon mixtures and analysed using reflectron time-of-flight mass spectrometer with variable electron energy ionization source. Acetylene clusters composed of more than a hundred acetylene molecules are generated at the acetylene concentration of Almost-Equal-To 8%, while mixed species are produced at low concentrations ( Almost-Equal-To 0.7%). The electron energy dependence of the mass spectra revealed the ionization process mechanisms in clusters. The ionization above the threshold for acetylene molecule of 11.5 eV results in the main ionic fragment progression (C{sub 2}H{sub 2}){sub n}{sup +}. At the electron energies Greater-Than-Or-Slanted-Equal-To 21.5 eV above the CH+CH{sup +} dissociative ionization limit of acetylene the fragment ions nominally labelled as (C{sub 2}H{sub 2}){sub n}CH{sup +}, n Greater-Than-Or-Slanted-Equal-To 2, are observed. For n Less-Than-Or-Slanted-Equal-To 7 these fragments correspond to covalently bound ionic structures as suggested by the observed strong dehydrogenation [(C{sub 2}H{sub 2}){sub n}-k Multiplication-Sign H]{sup +} and [(C{sub 2}H{sub 2}){sub n}CH -k Multiplication-Sign H]{sup +}. The dehydrogenation is significantly reduced in the mixed clusters where evaporation of Ar instead of hydrogen can stabilize the nascent molecular ion. The C{sub 3}H{sub 3}{sup +} ion was previously assigned to originate from the benzene molecular ion; however, the low appearance energy of Almost-Equal-To 13.7 eV indicates that a less rigid covalently bound structure of C{sub 6}H{sub 6}{sup +} ion must also be formed upon the acetylene cluster electron ionization. The appearance energy of Ar{sub n}(C{sub 2}H{sub 2}){sup +} fragments above Almost-Equal-To 15.1 eV indicates that the argon ionization is the first step in the fragment ion production, and the appearance energy of Ar{sub n{>=}2}(C{sub 2}H{sub 2}){sub m{>=}2}{sup +} at Almost-Equal-To 13

  10. Pressure (Or No Royal Road)

    ERIC Educational Resources Information Center

    Bradley, J.

    1973-01-01

    Discusses how difficult the various problems of pressure, partial pressure, gas laws, and vapor pressure are for students. Outlines the evolution of the concept of pressure, the gas equation for a perfect gas, partial pressures, saturated vapor pressure, Avogadro's hypothesis, Raoult's law, and the vapor pressure of ideal solutions. (JR)

  11. Flexible band gap tuning of hexagonal boron nitride sheets interconnected by acetylenic bonds.

    PubMed

    Zhang, Hongyu; Luo, Youhua; Feng, Xiaojuan; Zhao, Lixia; Zhang, Meng

    2015-08-21

    The energetic and electronic properties of acetylenic-bond-interconnected hexagonal boron nitride sheets (BNyne), in which the number of rows of BN hexagonal rings (denoted as BN width) between neighboring arrays of acetylenic linkages increases consecutively, have been explored using first-principles calculations. Depending on the spatial position of B/N atoms with respect to the acetylenic linkages, there are two different types of configurations. The band structure features and band gap evolutions of BNyne structures as a function of the BN width can be categorized into two families, corresponding to two distinct types of configurations. In particular, for both types of BNyne structures, the band gap variations exhibit odd-even oscillating behavior depending on the BN width, which is related to the different symmetries of acetylenic chains in the unit cell. These results suggest that the embedded linear acetylenic chains can provide more flexibility for manipulation of the atomic and electronic properties of hexagonal boron nitride. These sp-sp(2) hybrid structures might promise importantly potential applications for developing nanoscale electronic and optoelectronic devices. PMID:26194068

  12. Mid-Infrared Pumped Laser-Induced Thermal Grating Spectroscopy for Detection of Acetylene in the Visible Spectral Range.

    PubMed

    Sahlberg, Anna-Lena; Kiefer, Johannes; Aldén, Marcus; Li, Zhongshan

    2016-06-01

    We present mid-infrared laser-induced thermal grating spectroscopy (IR-LITGS) using excitation radiation around 3 µm generated by a simple broadband optical parametric oscillator (OPO). Acetylene as a typical small hydrocarbon molecule is used as an example target species. A mid-infrared broadband OPO pumped by the fundamental output of a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser was used to generate the pump beams, with pulse energies of 6-10 mJ depending on the wavelength. The line width of the OPO idler beam was ∼5 cm(-1), which is large enough to cover up to six adjacent acetylene lines. The probe beam was the radiation of a 532 nm cw solid state laser with 190 mW output power. Signals were generated in atmospheric pressure gas flows of N2, air, CO2 and Ar with small admixtures of C2H2 A detection limit of less than 300 ppm was found for a point measurement of C2H2 diluted in N2 As expected, the oscillation frequency of the IR-LITGS signal was found to have a large dependency on the buffer gas, which allows determination of the speed of sound. Moreover, the results reveal a very strong collisional energy exchange between C2H2 and CO2 compared to the other gases. This manifests as significant local heating. In summary, the MIR-LITGS technique enables spectroscopy of fundamental vibrational transitions in the infrared via detection in the visible spectral range. PMID:27091904

  13. Partial molar volume, surface area, and hydration changes for equilibrium unfolding and formation of aggregation transition state: High-pressure and cosolute studies on recombinant human IFN-γ

    PubMed Central

    Webb, Jonathan N.; Webb, Serena D.; Cleland, Jeffrey L.; Carpenter, John F.; Randolph, Theodore W.

    2001-01-01

    The equilibrium dissociation of recombinant human IFN-γ was monitored as a function of pressure and sucrose concentration. The partial molar volume change for dissociation was −209 ± 13 ml/mol of dimer. The specific molar surface area change for dissociation was 12.7 ± 1.6 nm2/molecule of dimer. The first-order aggregation rate of recombinant human IFN-γ in 0.45 M guanidine hydrochloride was studied as a function of sucrose concentration and pressure. Aggregation proceeded through a transition-state species, N*. Sucrose reduced aggregation rate by shifting the equilibrium between native state (N) and N* toward the more compact N. Pressure increased aggregation rate through increased solvation of the protein, which exposes more surface area, thus shifting the equilibrium away from N toward N*. The changes in partial molar volume and specific molar surface area between the N* and N were −41 ± 9 ml/mol of dimer and 3.5 ± 0.2 nm2/molecule, respectively. Thus, the structural change required for the formation of the transition state for aggregation is small relative to the difference between N and the dissociated state. Changes in waters of hydration were estimated from both specific molar surface area and partial molar volume data. From partial molar volume data, estimates were 25 and 128 mol H2O/mol dimer for formation of the aggregation transition state and for dissociation, respectively. From surface area data, estimates were 27 and 98 mol H2O/mol dimer. Osmotic stress theory yielded values ≈4-fold larger for both transitions. PMID:11381145

  14. An Experimental and Theoretical Study of Nitrogen-Broadened Acetylene Lines

    NASA Technical Reports Server (NTRS)

    Thibault, Franck; Martinez, Raul Z.; Bermejo, Dionisio; Ivanov, Sergey V.; Buzykin, Oleg G.; Ma, Qiancheng

    2014-01-01

    We present experimental nitrogen-broadening coefficients derived from Voigt profiles of isotropic Raman Q-lines measured in the 2 band of acetylene (C2H2) at 150 K and 298 K, and compare them to theoretical values obtained through calculations that were carried out specifically for this work. Namely, full classical calculations based on Gordon's approach, two kinds of semi-classical calculations based on Robert Bonamy method as well as full quantum dynamical calculations were performed. All the computations employed exactly the same ab initio potential energy surface for the C2H2N2 system which is, to our knowledge, the most realistic, accurate and up-to-date one. The resulting calculated collisional half-widths are in good agreement with the experimental ones only for the full classical and quantum dynamical methods. In addition, we have performed similar calculations for IR absorption lines and compared the results to bibliographic values. Results obtained with the full classical method are again in good agreement with the available room temperature experimental data. The quantum dynamical close-coupling calculations are too time consuming to provide a complete set of values and therefore have been performed only for the R(0) line of C2H2. The broadening coefficient obtained for this line at 173 K and 297 K also compares quite well with the available experimental data. The traditional Robert Bonamy semi-classical formalism, however, strongly overestimates the values of half-width for both Qand R-lines. The refined semi-classical Robert Bonamy method, first proposed for the calculations of pressure broadening coefficients of isotropic Raman lines, is also used for IR lines. By using this improved model that takes into account effects from line coupling, the calculated semi-classical widths are significantly reduced and closer to the measured ones.

  15. Chromophores from Photolyzed Ammonia Reacting with Acetylene: Application to Jupiter’s Great Red Spot

    NASA Astrophysics Data System (ADS)

    Carlson, Robert W.; Baines, K. H.; Anderson, M. S.; Filacchione, G.

    2012-10-01

    The production mechanisms of chromophores at Jupiter, and notably at the Great Red Spot (GRS), have been long-standing puzzles. A clue to the formation of the GRS coloring agent may be the great height of this storm, which can upwell ammonia to pressure levels of a few hundred mbar where solar photons capable of dissociating NH3 penetrate. Acetylene formed at higher altitudes can diffuse down and react with the NH3 photodissociation products, forming a deposit that absorbs in the ultraviolet and visible region (Ferris and Ishikawa, J. Amer. Chem. Soc. 110, 4306-4312, 1988). We have investigated the system NH3 + C2H2 + CH4 using a Zn lamp emitting at 214 nm to produce NH2 + H and subsequent reaction products. The deposits produced in these reactions were analyzed by optical and infrared spectroscopy and soft-ionization (He*) time-of-flight mass spectroscopy. The combination of NH3 + CH4 produced no visibly absorbing material, but NH3 + C2H2 and NH3 + C2H2 + CH4 mixtures both produced a yellow-orange film whose transmission spectra are similar to that of the GRS obtained by Cassini VIMS. Infrared spectra show a strong band at 2056 wavenumbers which may arise from nitrile (-CN), isonitrile (-NC), or diazide (-CNN) functional groups. The high-resolution mass spectra are consistent with compounds of the form CnH2n+1Nm, similar to the products formed in NH3 + CH4 spark discharges (Molton and Ponnamperuma, Icarus 21, 166-174, 1974). We thank NASA's Planetary Atmospheres Program for support.

  16. Highly enantioselective reductive cyclization of acetylenic aldehydes via rhodium catalyzed asymmetric hydrogenation.

    PubMed

    Rhee, Jong Uk; Krische, Michael J

    2006-08-23

    Catalytic hydrogenation of acetylenic aldehydes 1a-12a using chirally modified cationic rhodium catalysts enables highly enantioselective reductive cyclization to afford cyclic allylic alcohols 1b-12b. Using an achiral hydrogenation catalyst, the chiral racemic acetylenic aldehydes 13a-15a engage in highly syn-diastereoselective reductive cyclizations to afford cyclic allylic alcohols 13b-15b. Ozonolysis of cyclization products 7b and 9b allows access to optically enriched alpha-hydroxy ketones 7c and 9c. Reductive cyclization of enyne 7a under a deuterium atmosphere provides the monodeuterated product deuterio-7b, consistent with a catalytic mechanism involving alkyne-carbonyl oxidative coupling followed by hydrogenolytic cleavage of the resulting oxametallacycle. These hydrogen-mediated transformations represent the first examples of the enantioselective reductive cyclization of acetylenic aldehydes. PMID:16910650

  17. Examining the impact of acetylene on N-fixation and the active sediment microbial community

    PubMed Central

    Fulweiler, Robinson W.; Heiss, Elise M.; Rogener, Mary Kate; Newell, Silvia E.; LeCleir, Gary R.; Kortebein, Sarah M.; Wilhelm, Steven W.

    2015-01-01

    Here we examined the impact of a commonly employed method used to measure nitrogen fixation, the acetylene reduction assay (ARA), on a marine sediment community. Historically, the ARA technique has been broadly employed for its ease of use, in spite of numerous known artifacts. To gauge the severity of these effects in a natural environment, we employed high-throughput 16S rRNA gene sequencing to detect differences in acetylene-treated sediments vs. non-treated control sediments after a 7 h incubation. Within this short time period, significant differences were seen across all activity of microbes identified in the sediment, implying that the changes induced by acetylene occur quickly. The results have important implications for our understanding of marine nitrogen budgets. Moreover, because the ARA technique has been widely used in terrestrial and freshwater habitats, these results may be applicable to other ecosystems. PMID:26029177

  18. Deactivation mechanisms for Pd/Al{sub 2}O{sub 3} acetylene hydrogenation catalysts

    SciTech Connect

    Hall, J.B.; Huggins, B.J.; Meyers, B.L.; Kaminsky, M.P.

    1994-12-31

    The selective hydrogenation of acetylenic impurities to ethylene is a crucial purification step in the production of olefins by steam cracking. This hydrogenation is done catalytically using a Pd/Al{sub 2}O{sub 3} catalyst in a fixed bed reactor. The designed lifetime of the catalyst in a front end acetylene converter is about 4 years. Accelerated catalyst deactivation and thermal runaways caused by loss in catalyst selectivity are common problems which plague acetylene converters. Such problems result in unscheduled shutdowns and increased costs to replace deactivated catalyst. This presentation outlines several deactivation mechanisms of the catalyst and discusses how they affect catalyst lifetime and performance. Catalyst characterization using electron microscopy and CO chemisorption provides information on how poisons deteriorate the catalyst and Pd particle size changes produced by use and regeneration. Thermal gravimetric analysis was also used to determine the extent of coke burn-off using less severe regeneration procedures.

  19. Effect of Protein Additives on Acetylene Reduction (Nitrogen Fixation) by Rhizobium in the Presence and Absence of Soybean Cells 1

    PubMed Central

    Anderson, Stephen J.; Phillips, Donald A.

    1976-01-01

    The effect of protein additives on acetylene reduction (N2 fixation) by Rhizobium associated with soybean cells (Glycine max [L.] Merr.) in vitro was studied. Acetylene reduction was promoted on the basal medium supplemented with 1.4 mg of N/ml supplied as aqueous extracts of hexane-extracted soybean, red kidney beans (Phaseolus vulgaris L.), or peas (Pisum sativum L.). Commercial samples of α-casein, or bovine serum albumin also promoted acetylene reduction at a concentration of 1.4 mg of N/ml of basal medium, but egg albumin supplying an equal amount of nitrogen to the basal medium completely suppressed acetylene reduction. Autoclaving the aqueous extract of hexane-extracted soybean meal had no effect on its ability to promote acetylene reduction. The presence of 40 mm succinate decreased acetylene reduction with leguminous proteins supplying 1.4 mg of N/ml but promoted acetylene reduction by Rhizobium 32H1-soybean cell associations on media containing α-casein, bovine serum albumin, or egg albumin suppling 1.4 mg of N/ml. Similar results were obtained with both cowpea Rhizobium 32H1 and Rhizobium japonicum 61A96. Pure cultures of Rhizobium 32H1 developed acetylene-reducing activity in the presence of soybean extract on basal agar medium and in vermiculite supplied with N-free mineral salts plus crude soybean meal. The results suggest that in certain situations, free living Rhizobium may reduce N2 under field conditions. PMID:16659592

  20. Estimation of nitrogenase activity in the presence of ethylene biosynthesis by use of deuterated acetylene as a substrate

    SciTech Connect

    Lin-Vien, D.; Fateley, W.G.; Davis, L.C. )

    1989-02-01

    Nitrogenase reduces deuterated acetylene primarily to cis dideuterated ethylene. This can be distinguished from undeuterated ethylene by the use of Fourier transform infrared spectroscopy. Characteristic bands in the region from 800 to 3,500 cm-1 can be used to identify and quantitate levels of these products. This technique is applicable to field studies of nitrogen fixation where ethylene biosynthesis by plants or bacteria is occurring. We have verified the reaction stoichiometry by using Klebsiella pneumoniae and Bradyrhizobium japonicum in soybeans. The most useful bands for quantitation of substrate purity and product distribution are as follows: acetylene-d0, 3,374 cm-1; acetylene-d1, 2,584 cm-1; acetylene-d2, 2,439 cm-1; cis-ethylene-d2, 843 cm-1; trans-ethylene-d2, 988 cm-1; ethylene-d1, 943 cm-1; ethylene-d0, 949 cm-1. (The various deuterated ethylenes and acetylenes are designated by a lowercase d and subscript to indicate the number, but not the position, of deuterium atoms in the molecule.) Mass spectrometry coupled to a gas chromatograph system has been used to assist in quantitation of the substrate and product distributions. Significant amounts of trans-ethylene-d2 were produced by both wild-type and nifV mutant K. pneumoniae. Less of this product was observed with the soybean system.

  1. Heats of Formation of Triplet Ethylene, Ethylidene, and Acetylene

    SciTech Connect

    Nguyen, M.T.; Matus, M.H.; Lester Jr, W.A.; Dixon, David A.

    2007-06-28

    Heats of formation of the lowest triplet state of ethylene and the ground triplet state of ethylidene have been predicted by high level electronic structure calculations. Total atomization energies obtained from coupled-cluster CCSD(T) energies extrapolated to the complete basis set limit using correlation consistent basis sets (CBS), plus additional corrections predict the following heats of formation in kcal/mol: Delta H0f(C2H4,3A1) = 80.1 at 0 K and 78.5 at 298 K, and Delta H0f(CH3CH,3A") = 86.8 at 0 K and 85.1 at 298 K, with an error of less than +-1.0 kcal/mol. The vertical and adiabatic singlet-triplet separation energies of ethylene were calculated as Delta ES-T,vert = 104.1 and Delta ES-T,adia = 65.8 kcal/mol. These results are in excellent agreement with recent quantum Monte Carlo (DMC) values of 103.5 +- 0.3 and 66.4 +- 0.3 kcal/mol. Both sets of computational values differ from the experimental estimate of 58 +- 3 kcal/mol for the adiabatic splitting. The computed singlet-triplet gap at 0 K for acetylene is Delta ES-T,adia(C2H2) = 90.5 kcal/mol, which is in notable disagreement with the experimental value of 82.6 kcal/mol. The heat of formation of the triplet is Delta H0f(C2H2,3B2) = 145.3 kcal/mol. There is a systematic underestimation of the singlet-triplet gaps in recent photodecomposition experiments by ~;;7 to 8 kcal/mol. For vinylidene, we predict Delta H0f(H2CC,1A1) = 98.8 kcal/mol at 298 K (exptl. 100.3 +- 4.0), Delta H0f(H2CC,3B2) = 146.2 at 298 K, and an energy gap Delta ES-T-adia(H2CC) = 47.7 kcal/mol.

  2. Simulations of shock-induced mixing& combustion of an acetylene cloud in a chamber

    SciTech Connect

    Bell, J B; Day, M S; Beckner, V E; Kuhl, A L; Neuwald, P; Reichenbach, H

    2001-02-06

    In this paper we present numerical simulations of the interaction of a blast wave with an acetylene bubble in a closed chamber. We model the system using the inviscid Euler equations for a mixture of ideal gases. The formulation specifies the thermodynamic behavior of the system using a Chemkin interface and includes the capability to model combustion as the ambient air mixes with the acetylene. The simulations are performed using a three-dimensional adaptive mesh refinement algorithm based on a second-order Godunov integration scheme. Simulations are compared with experimental measurements for the same configuration.

  3. Diffusion of acetylene inside the Cu-BTC metal organic framework

    NASA Astrophysics Data System (ADS)

    Prabhudesai, S. A.; Sharma, V. K.; Mitra, S.; Mukhopadhyay, R.

    2012-06-01

    Dynamic of acetylene molecule adsorbed in Copper 1, 3, 5-benzenetricarboxylate metal-organic framework as studied using molecular dynamics simulation technique is reported here. The results showed that the translational motion of the guest molecule exist in two different time scales; faster one behave as free particle and other one is found to follow jump diffusion. Rotational motion of acetylene is found to be an order of magnitude faster than translational motion. Intermediate scattering functions corresponding to rotational motion show an unusual dip, which is described by the m-diffusion model.

  4. Acetylene- and Phenylacetylene-Terminated Poly(Arylene Ether Benzimidazole)s (PAEBI's)

    NASA Technical Reports Server (NTRS)

    Connell, John W.; Hergenrother, Paul M.; Smith, Joseph G., Jr.

    1994-01-01

    Polymers prepared by first synthesizing polymers terminated with hydroxy groups, then reacting them with either 4-ethynylbenzoyl chloride or 4-fluoro-4'-phenylethynylbenzophenone. Endcapped polymers thermally cured to yield materials with attractive combination of properties. Cured acetylene-and phenylacetylene-terminated PAEBI's exhibit higher glass-transition temperatures and better retention of mechanical properties at high temperatures. Cured acetylene- and phenylacetylene-terminated polymers exhibit excellent adhesion to copper foil and polyimide film. Potentially useful as adhesives, coatings, composite matrices, fibers, films, membranes, and moldings.

  5. Strength and ductility of room-dry and water-saturated igneous rocks at low pressures and temperatures to partial melting. Final report

    SciTech Connect

    Friedman, M.; Handin, J.; Higgs, N.G.; Lantz, J.R.; Bauer, S.J.

    1980-11-01

    Rock types that are likely candidates for drilling were tested. Reported herein are the short-time ultimate strengths and ductilities determined at temperatures of 25/sup 0/ to 1050/sup 0/C and a strain rate of 10/sup -4/s/sup -1/ of (a) room-dry Mt. Hood Andesite, Cuerbio Basalt, and Charcoal (St. Cloud Gray) Granodiorite at confining pressures of 0, 50, and 100 MPa, (b) water-saturated specimens of the same three rocks at zero effective pressure (both pore and confining pressures of 50 MPa), and (c) room-dry Newberry Rhyolite Obsidian at 0 and 50 MPa. These strengths are then compared with the stresses developed at the wall of a borehole in an elastic medium at the appropriate temperatures and mean pressures to assess the problem of borehole stability. (MHR)

  6. Near-infrared spectra of liquid/solid acetylene under Titan relevant conditions and implications for Cassini/VIMS detections

    NASA Astrophysics Data System (ADS)

    Singh, S.; Cornet, T.; Chevrier, V. F.; Combe, J.-Ph.; McCord, T. B.; Roe, L. A.; Le Mouélic, S.; Le Menn, E.; Wasiak, F. C.

    2016-05-01

    Acetylene is thought to be abundant on Titan according to most photochemical models. While detected in the atmosphere, its likely presence at the surface still lacks physical evidence. It is thought that solid acetylene could be a major component of Titan's lakes shorelines and dry lakebed, detected as the 5 μm-bright deposits with the Cassini/VIMS instrument. Acetylene could also be present under its liquid form as dissolved solids in Titan's methane-ethane lakes, as emphasized by thermodynamics studies. This paper is devoted to the near-infrared spectroscopy study of acetylene under solid and liquid phases between 1 and 2.2 μm, synthesized in a Titan simulation chamber that is able to reproduce extreme temperature conditions. From experiments, we observed a ∼10% albedo increase between liquid acetylene at 193-188 K and solid acetylene at 93 K. Using the NIR spectroscopy technique we successfully calculated the reflectivity ratio of solid/liquid acetylene as 1.13. The second difference we observed between liquid and solid acetylene is a shift in the major absorption band detected at 1.54 μm, the shift of ∼0.01 μm occurring toward higher wavelength. In order to assess the detectability of acetylene on Titan using the Cassini/VIMS instrument, we adapted our spectra to the VIMS spectral resolution. The spectral band at 1.55 μm and a negative slope at 2.0 μm falls in the Cassini/VIMS atmospheric windows over several VIMS infrared spectels, thus Cassini/VIMS should be able to detect acetylene.

  7. High performance addition-type thermoplastics (ATTs) - Evidence for the formation of a Diels-Alder adduct in the reaction of an acetylene-terminated material and a bismaleimide

    NASA Technical Reports Server (NTRS)

    Pater, R. H.; Soucek, M. D.; Chang, A. C.; Partos, R. D.

    1991-01-01

    Recently, the concept and demonstration of a new versatile synthetic reaction for making a large number of high-performance addition-type thermoplastics (ATTs) were reported. The synthesis shows promise for providing polymers having an attractive combination of easy processability, good toughness, respectable high temperature mechanical performance, and excellent thermo-oxidative stability. The new chemistry involves the reaction of an acetylene-terminated material with a bismaleimide or benzoquinone. In order to clarify the reaction mechanism, model compound studies were undertaken in solutions as well as in the solid state. The reaction products were purified by flash chromatography and characterized by conventional analytical techniques including NMR, FT-IR, UV-visible, mass spectroscopy, and high pressure liquid chromatography. The results are presented of the model compound studies which strongly support the formation of a Diels-Alder adduct in the reaction of an acetylene-terminated compound and a bismaleimide or benzoquinone.

  8. 46 CFR 154.1735 - Methyl acetylene-propadiene mixture.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... following features: (1) A vapor compressor that does not raise the temperature and pressure of the vapor... each cylinder in the same stage of a reciprocating compressor that has: (i) Two temperature actuated... wheelhouse when any of the high pressure or high temperature switches under paragraphs (b)(2)(i) and...

  9. 46 CFR 154.1735 - Methyl acetylene-propadiene mixture.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... following features: (1) A vapor compressor that does not raise the temperature and pressure of the vapor... each cylinder in the same stage of a reciprocating compressor that has: (i) Two temperature actuated... wheelhouse when any of the high pressure or high temperature switches under paragraphs (b)(2)(i) and...

  10. Calculation of the standard partial molal thermodynamic properties of KCl{sup 0} and activity coefficients of aqueous KCl at temperatures and pressures to 1000{degree}C and 5 kbar

    SciTech Connect

    Pokrovskii, V.A.; Helgeson, H.C.

    1997-06-01

    Regression of experimental activity coefficient and dissociation constant data reported in the literature with the Hueckel and Setchenow equations and the revised HKF equations of state generated parameters and thermodynamic properties of dissociated KCl and KCl{sup 0} at 25{degrees}C and bar that can be used to calculate the standard partial molal thermodynamic properties of KCl{sup 0} and the activity coefficients of KCl at temperatures and pressures to 1000{degrees}C and 5 kbar. 46 refs., 6 figs., 4 tabs.

  11. Association Mechanisms of Unsaturated C2 Hydrocarbons with Their Cations: Acetylene and Ethylene

    NASA Technical Reports Server (NTRS)

    Bera, Partha P.; Head-Gordon, Martin; Lee, Timothy J.

    2013-01-01

    The ion-molecule association mechanism of acetylene and ethylene with their cations is investigated by ab initio quantum chemical methods to understand the structures, association energies, and the vibrational and electronic spectra of the products. Stable puckered cyclic isomers are found as the result of first forming less stable linear and bridge isomers. The puckered cyclic complexes are calculated to be strongly bound, by 87, 35 and 56 kcal/mol for acetylene-acetylene cation, ethylene-ethylene cation and acetylene-ethylene cation, respectively. These stable complexes may be intermediates that participate in further association reactions. There are no association barriers, and no significant inter-conversion barriers, so the initial linear and bridge encounter complexes are unlikely to be observable. However, the energy gap between the bridged and cyclic puckered isomers greatly differs from complex to complex: it is 44 kcal/mol in C4H4 +, but only 6 kcal/mol in C4H8 +. The accurate CCSD(T) calculations summarized above are also compared against less computationally expensive MP2 and density functional theory (DFT) calculations for structures, relative energies, and vibrational spectra. Calculated vibrational spectra are compared against available experiments for cyclobutadiene cation. Electronic spectra are also calculated using time-dependent DFT.

  12. 46 CFR 151.50-79 - Methyl acetylene-propadiene mixture.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... acetylene-propadiene mixture must have a refrigeration system that does not compress the cargo vapor or have a refrigeration system with the following features: (1) A vapor compressor that does not raise the... suction line. (c) The piping system, including the cargo refrigeration system, for tanks to be loaded...

  13. 46 CFR 151.50-79 - Methyl acetylene-propadiene mixture.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... acetylene-propadiene mixture must have a refrigeration system that does not compress the cargo vapor or have a refrigeration system with the following features: (1) A vapor compressor that does not raise the... suction line. (c) The piping system, including the cargo refrigeration system, for tanks to be loaded...

  14. 46 CFR 151.50-79 - Methyl acetylene-propadiene mixture.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... acetylene-propadiene mixture must have a refrigeration system that does not compress the cargo vapor or have a refrigeration system with the following features: (1) A vapor compressor that does not raise the... suction line. (c) The piping system, including the cargo refrigeration system, for tanks to be loaded...

  15. 46 CFR 151.50-79 - Methyl acetylene-propadiene mixture.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... acetylene-propadiene mixture must have a refrigeration system that does not compress the cargo vapor or have a refrigeration system with the following features: (1) A vapor compressor that does not raise the... suction line. (c) The piping system, including the cargo refrigeration system, for tanks to be loaded...

  16. 46 CFR 151.50-79 - Methyl acetylene-propadiene mixture.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... acetylene-propadiene mixture must have a refrigeration system that does not compress the cargo vapor or have a refrigeration system with the following features: (1) A vapor compressor that does not raise the... suction line. (c) The piping system, including the cargo refrigeration system, for tanks to be loaded...

  17. OZONE PRODUCTION FROM IRRADIATION OF ACETYLENE/CHLORINE MIXTURES IN AIR

    EPA Science Inventory

    The reaction of chlorine radicals with acetylene in air in the absence of oxides of nitrogen result In the formation of ozone. o ozone is observed when chlorine radicals react with methylacetylene or ethylacetylene under similar conditions. ormyl chloride is observed in all syste...

  18. Methane emissions measured at two California landfills by OTM-10 and an acetylene tracer method

    EPA Science Inventory

    Methane emissions were measured at two municipal solid waste landfills in California using static flux chambers, an optical remote sensing approach known as vertical radial plume mapping (VRPM) using a tunable diode laser (TDL) and a novel acetylene tracer method. The tracer meth...

  19. Conformational flexibility of fused tetracenedione propellers obtained from one-pot reductive dimerization of acetylenic quinones.

    PubMed

    Vasilevsky, Sergei F; Baranov, Denis S; Mamatyuk, Victor I; Fadeev, Dmitry S; Gatilov, Yurii V; Stepanov, Aleksandr A; Vasilieva, Nadezhda V; Alabugin, Igor V

    2015-02-01

    Reductive dimerization of acetylenic anthraquinones provides synthetic access to flexible nonplanar polyaromatics with a tetracenedione core. In solution, these nonplanar, contorted polycycles exist as equilibrating mixtures of two symmetric conformers. The fused tetracenediones are easily reduced and exhibit rich electrochemical behavior. PMID:25575160

  20. Selective hydrogenation of dienic and acetylenic compounds on metal-containing catalysts

    NASA Astrophysics Data System (ADS)

    Stytsenko, V. D.; Mel'nikov, D. P.

    2016-05-01

    Studies on selective hydrogenation of dienic and acetylenic hydrocarbons and their derivatives on metal-containing catalysts are reviewed. The review covers publications over a wide period of time and concentrates on the fundamental principles of catalyst operation. The catalysts modified in the surface layer were shown to be promising for selective hydrogenation.

  1. A Safe and Easy Classroom Demonstration of the Generation of Acetylene Gas.

    ERIC Educational Resources Information Center

    Cox, Marilyn Blagg; Krause, Paul

    1994-01-01

    In this demonstration of the generation and combustion of acetylene, calcium carbide and water are allowed to react in a latex examination glove. Two student volunteers perform the demonstration with instructor guidance. This safe, popular demonstration, originally intended to illustrate the alkyne family of compounds, can be used with a variety…

  2. Laboratory astrochemistry: catalytic conversion of acetylene to polycyclic aromatic hydrocarbons over SiC grains.

    PubMed

    Zhao, T Q; Li, Q; Liu, B S; Gover, R K E; Sarre, P J; Cheung, A S-C

    2016-02-01

    Catalytic conversion reactions of acetylene on a solid SiC grain surface lead to the formation of polycyclic aromatic hydrocarbons (PAHs) and are expected to mimic chemical processes in certain astrophysical environments. Gas-phase PAHs and intermediates were detected in situ using time-of-flight mass spectrometry, and their formation was confirmed using GC-MS in a separate experiment by flowing acetylene gas through a fixed-bed reactor. Activation of acetylene correlated closely with the dangling bonds on the SiC surface which interact with and break the C-C π bond. The addition of acetylene to the resulting radical site forms a surface ring structure which desorbs from the surface. The results of HRTEM and TG indicate that soot and graphene formation on the SiC surface depends strongly on reaction temperature. We propose that PAHs as seen through the 'UIR' emission bands can be formed through decomposition of a graphene-like material, formed on the surface of SiC grains in carbon-rich circumstellar envelopes. PMID:26752613

  3. TOXICITY OF ACETYLENIC ALCOHOLS TO THE FATHEAD MINNOW, PIMEPHALES PROMELAS: NARCOSIS AND PROELECTROPHILE ACTIVATION

    EPA Science Inventory

    The 96-h LC50 values for 16 acetylenic alcohols in the fathead minnow (Pimephales promelas) were determined using continuous-flow diluters. The measured LC50 values for seven tertiary propargylic alcohols agreed closely with the QSAR predictions based upon data for other organic ...

  4. Mechanism of tungsten-dependent acetylene hydratase from quantum chemical calculations.

    PubMed

    Liao, Rong-Zhen; Yu, Jian-Guo; Himo, Fahmi

    2010-12-28

    Acetylene hydratase is a tungsten-dependent enzyme that catalyzes the nonredox hydration of acetylene to acetaldehyde. Density functional theory calculations are used to elucidate the reaction mechanism of this enzyme with a large model of the active site devised on the basis of the native X-ray crystal structure. Based on the calculations, we propose a new mechanism in which the acetylene substrate first displaces the W-coordinated water molecule, and then undergoes a nucleophilic attack by the water molecule assisted by an ionized Asp13 residue at the active site. This is followed by proton transfer from Asp13 to the newly formed vinyl anion intermediate. In the subsequent isomerization, Asp13 shuttles a proton from the hydroxyl group of the vinyl alcohol to the α-carbon. Asp13 is thus a key player in the mechanism, but also W is directly involved in the reaction by binding and activating acetylene and providing electrostatic stabilization to the transition states and intermediates. Several other mechanisms are also considered but the energetic barriers are found to be very high, ruling out these possibilities. PMID:21149684

  5. Purification and characterization of acetylene hydratase of Pelobacter acetylenicus, a tungsten iron-sulfur protein.

    PubMed Central

    Rosner, B M; Schink, B

    1995-01-01

    Acetylene hydratase of the mesophilic fermenting bacterium Pelobacter acetylenicus catalyzes the hydration of acetylene to acetaldehyde. Growth of P. acetylenicus with acetylene and specific acetylene hydratase activity depended on tungstate or, to a lower degree, molybdate supply in the medium. The specific enzyme activity in cell extract was highest after growth in the presence of tungstate. Enzyme activity was stable even after prolonged storage of the cell extract or of the purified protein under air. However, enzyme activity could be measured only in the presence of a strong reducing agent such as titanium(III) citrate or dithionite. The enzyme was purified 240-fold by ammonium sulfate precipitation, anion-exchange chromatography, size exclusion chromatography, and a second anion-exchange chromatography step, with a yield of 36%. The protein was a monomer with an apparent molecular mass of 73 kDa, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The isoelectric point was at pH 4.2. Per mol of enzyme, 4.8 mol of iron, 3.9 mol of acid-labile sulfur, and 0.4 mol of tungsten, but no molybdenum, were detected. The Km for acetylene as assayed in a coupled photometric test with yeast alcohol dehydrogenase and NADH was 14 microM, and the Vmax was 69 mumol.min-1.mg of protein-1. The optimum temperature for activity was 50 degrees C, and the apparent pH optimum was 6.0 to 6.5. The N-terminal amino acid sequence gave no indication of resemblance to any enzyme protein described so far. PMID:7592321

  6. Seasonal Variations of Temperature, Acetylene and Ethane in Saturn's Stratosphere from 2005 to 2010

    NASA Astrophysics Data System (ADS)

    Sinclair, James; Irwin, P. G. J.; Fletcher, L. N.; Moses, J. I.; Greathouse, T. K.; Friedson, A. J.; Hesman, B.; Hurley, J.; Merlet, C.

    2012-10-01

    Acetylene (C2H2) and ethane (C2H6) exemplify by-products of complex photochemistry in Saturn’s stratosphere. Their relative stability together with their strong vertical gradients in concentration allow for their use as tracers of vertical motion in Saturn’s lower stratosphere. Earlier studies of Saturn's hydrocarbons have provided only a snapshot of their behaviour with temporal variations remaining to be determined. In this study, we investigate how the thermal structure and concentrations of acetylene and ethane have evolved on Saturn with the changing season. We use FIRMAP (15.5 cm-1 spectral resolution) Cassini-CIRS observations, initially retrieve temperature and subsequently retrieve the abundances of acetylene and ethane. In comparing 2005, 2009 and 2010 results, we observe the disappearance of Saturn's southern warm polar hood with cooling of up to 18.6 K ± 0.9 K at 1.1 mbar south of 75°S (planetographic). This suggests dissipation of Saturn's south polar vortex in addition to an autumnal cooling. We observe a 20% ± 9% enrichment of acetylene and a 30% ± 10% enrichment of ethane at 2.1 mbar at 25°N, together with a 14% ± 9% depletion of acetylene and an 18% ± 7% depletion of ethane at the same altitude at 15°S. This suggests the presence of localised downwelling and upwelling at these latitudes, respectively. These vertical motions are consistent with a recently-developed GCM (global circulation model) of Saturn's tropopause and stratosphere, which predicts this pattern of upwelling and downwelling as a result of seasonally-reversing Hadley circulation.

  7. Rotationally Resolved Vacuum Ultraviolet Resonance-Enhanced Multiphoton Ionization (VUV REMPI) of Acetylene via the G̃ Rydberg State.

    PubMed

    Schmidt-May, Alice F; Grütter, Monika; Neugebohren, Jannis; Kitsopoulos, T N; Wodtke, Alec M; Harding, Dan J

    2016-07-14

    We present a 1 + 1' resonance-enhanced multiphoton ionization (REMPI) scheme for acetylene via the linear G̃ 4sσ (1)Πu Rydberg state, offering partial rotational resolution and the possibility to detect excitation in both the cis- and trans-bending modes. The resonant transition to the G̃ state is driven by a vacuum ultraviolet (VUV) photon, generated by resonant four-wave mixing (FWM) in krypton. Ionization from the short-lived G̃ state then occurs quickly, driven by the high intensity of the residual light from the FWM process. We have observed nine bands in the region between 79 200 cm(-1) and 80 500 cm(-1) in C2H2 and C2D2. We compare our results with published spectra in this region and suggest alternative assignments for some of the Renner-Teller split bands. Similar REMPI schemes should be applicable to other small molecules with picosecond lifetime Rydberg states. PMID:27073931

  8. Epilepsy (partial)

    PubMed Central

    2011-01-01

    Introduction About 3% of people will be diagnosed with epilepsy during their lifetime, but about 70% of people with epilepsy eventually go into remission. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of starting antiepileptic drug treatment following a single seizure? What are the effects of drug monotherapy in people with partial epilepsy? What are the effects of additional drug treatments in people with drug-resistant partial epilepsy? What is the risk of relapse in people in remission when withdrawing antiepileptic drugs? What are the effects of behavioural and psychological treatments for people with epilepsy? What are the effects of surgery in people with drug-resistant temporal lobe epilepsy? We searched: Medline, Embase, The Cochrane Library, and other important databases up to July 2009 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 83 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review we present information relating to the effectiveness and safety of the following interventions: antiepileptic drugs after a single seizure; monotherapy for partial epilepsy using carbamazepine, gabapentin, lamotrigine, levetiracetam, phenobarbital, phenytoin, sodium valproate, or topiramate; addition of second-line drugs for drug-resistant partial epilepsy (allopurinol, eslicarbazepine, gabapentin, lacosamide, lamotrigine, levetiracetam, losigamone, oxcarbazepine, retigabine, tiagabine, topiramate, vigabatrin, or zonisamide); antiepileptic drug withdrawal for people with partial or

  9. Severe acute respiratory failure managed with continuous positive airway pressure and partial extracorporeal carbon dioxide removal by an artificial membrane lung. A controlled, randomized animal study.

    PubMed

    Borelli, M; Kolobow, T; Spatola, R; Prato, P; Tsuno, K

    1988-12-01

    Using an animal model of acute respiratory failure (ARF), we evaluated two treatments: conventional mechanical pulmonary ventilation (MV) and continuous positive airway pressure (CPAP) with extracorporeal removal of CO2 by an artificial membrane lung. We developed a model of "mild" ARF and a model of "severe" ARF after ventilating healthy sheep at a peak inspiratory pressure of 50 cm H2O for various lengths of time. Sheep from either injury models were randomly assigned to one of the above treatment groups. All 16 sheep from the model with "severe" ARF died, with progressive deterioration in pulmonary function and multiorgan failure irrespective of the treatment. Of 11 sheep from the model with "mild" ARF treated by MV, only three survived, whereas all 11 sheep from the model with "mild" ARF treated with CPAP and extracorporeal removal of CO2 responded well, and nine sheep ultimately recovered. We conclude that CPAP with extracorporeal removal of CO2 provided a better environment for the recovery in our model with "mild" ARF than the conventional arrangement centered on MV alone. Our studies also suggest that lung injury can progress (i.e., model with "severe" ARF) to where neither of the two treatments can succeed. PMID:3144216

  10. Acetylene hydratase of Pelobacter acetylenicus. Molecular and spectroscopic properties of the tungsten iron-sulfur enzyme.

    PubMed

    Meckenstock, R U; Krieger, R; Ensign, S; Kroneck, P M; Schink, B

    1999-08-01

    Acetylene hydratase of Pelobacter acetylenicus is a tungsten iron-sulfur protein involved in the fermentation of acetylene to ethanol and acetate. Expression of the enzyme was increased 10-fold by feeding a 50-L batch culture continuously with 104 Pa acetylene at pH 6.8-7.0. Acetylene hydratase was purified to homogeneity by a three-step procedure in either the absence or presence of dioxygen. The enzyme was a monomer with a molecular mass of 73 kDa (SDS/PAGE) or 83 kDa (matrix-assisted laser-desorption ionization MS) and contained 0.5 +/- 0.1 W (inductively coupled plasma/MS) and 1.3 +/- 0.1 molybdopterin-guanine dinucleotide per mol. Selenium was absent. EPR spectra (enzyme as isolated, under air) showed a signal typical of a [3Fe-4S] cluster with gav = 2.01, at 10 K. In enzyme prepared under N2/H2, this signal was absent and reaction with dithionite led to a rhombic signal with gz = 2.048, gy = 1.939 and gx = 1.920 indicative of a low-potential ferredoxin-type [4Fe-4S] cluster. Upon oxidation with hexacyanoferrate(III), a new signal appeared with gx = 2.007, gy = 2.019 and gz = 2.048 (gav = 2.022), which disappeared after further oxidation. The signal was still visible at 150 K and was tentatively assigned to a W(V) center. The iron-sulfur center of acetylene hydratase (prepared under N2/H2) gave a midpoint redox potential of -410 +/- 20 mV in a spectrophotometric titration with dithionite. Enzyme activity depended on the redox potential of the solution, with 50% of maximum activity at -340 +/- 20 mV. The presence of a pterin-guanine dinucleotide cofactor differentiates acetylene hydratase from the aldehyde ferredoxin oxidoreductase-type enzymes which have a pterin mononucleotide cofactor. PMID:10447686

  11. A potential plant-derived antifungal acetylenic acid mediates its activity by interfering with fatty acid homeostasis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    6-Nonadecynoic acid (6-NDA), a plant-derived acetylenic acid, exhibits strong inhibitory activity against the human fungal pathogens Candida albicans, Aspergillus fumigatus, and Trichophyton mentagrophytes. In the present study, transcriptional profiling coupled with mutant and biochemical analyses...

  12. Effects of sulfide and low redox potential on the inhibition of nitrous oxide reduction by acetylene in Pseudomonas nautica.

    PubMed

    Jensen, K M; Cox, R P

    1992-09-01

    Membrane introduction mass spectrometry was used to investigate the inhibitory effect of acetylene on the nitrous oxide reductase activity of intact cells of Pseudomonas nautica. We studied the effects of the concentrations of nitrate and sulfide, and the redox potential, which have all been implicated in causing a decrease in the inhibitory effects of acetylene during measurements of denitrification in natural environments. There was no evidence that the concentration of nitrate influenced the effect of acetylene. Lowering the redox potential with the reductant Ti(III)-nitrilotriacetate caused a slight alleviation of acetylene inhibition. Much greater effects at the same redox potential were obtained with concentrations of sulfide in the range 1-10 microM. PMID:1526461

  13. Overexpression of iron superoxide dismutase in transformed poplar modifies the regulation of photosynthesis at low CO2 partial pressures or following exposure to the prooxidant herbicide methyl viologen.

    PubMed

    Arisi, A C; Cornic, G; Jouanin, L; Foyer, C H

    1998-06-01

    Chloroplast-targeted overexpression of an Fe superoxide dismutase (SOD) from Arabidopsis thaliana resulted in substantially increased foliar SOD activities. Ascorbate peroxidase, glutathione reductase, and monodehydroascorbate reductase activities were similar in the leaves from all of the lines, but dehydroascorbate reductase activity was increased in the leaves of the FeSOD transformants relative to untransformed controls. Foliar H2O2, ascorbate, and glutathione contents were comparable in all lines of plants. Irradiance-dependent changes in net CO2 assimilation and chlorophyll a fluorescence quenching parameters were similar in all lines both in air (21% O2) and at low (1%) O2. CO2-response curves for photosynthesis showed similar net CO2-exchange characteristics in all lines. In contrast, values of photochemical quenching declined in leaves from untransformed controls at intercellular CO2 (Ci) values below 200 microL L-1 but remained constant with decreasing Ci in leaves of FeSOD transformants. When the O2 concentration was decreased from 21 to 1%, the effect of FeSOD overexpression on photochemical quenching at limiting Ci was abolished. At high light (1000 micromol m-2 s-1) a progressive decrease in the ratio of variable (Fv) to maximal (Fm) fluorescence was observed with decreasing temperature. At 6(o)C the high-light-induced decrease in the Fv/Fm ratio was partially prevented by low O2 but values were comparable in all lines. Methyl viologen caused decreased Fv/Fm ratios, but this was less marked in the FeSOD transformants than in the untransformed controls. These observations suggest that the rate of superoxide dismutation limits flux through the Mehler-peroxidase cycle in certain conditions. PMID:9625709

  14. A detailed kinetic modeling study of aromatics formation in laminar premixed acetylene and ethylene flames

    SciTech Connect

    Wang, H.; Frenklach, M.

    1997-07-01

    A computational study was performed for the formation and growth of polycyclic aromatic hydrocarbons (PAHs) in laminar premixed acetylene and ethylene flames. A new detailed reaction mechanism describing fuel pyrolysis and oxidation, benzene formation, and PAH mass growth and oxidation is presented and critically tested. It is shown that the reaction model predicts reasonably well the concentration profiles of major and intermediate species and aromatic molecules in a number of acetylene and ethylene flames reported in the literature. It is demonstrated that reactions of n-C{sub 4}H{sub x} + C{sub 2}H{sub 2} leading to the formation of one-ring aromatics are as important as the propargyl recombination, and hence must be included in kinetic modeling of PAH formation in hydrocarbon flames. It is further demonstrated that the mass growth of PAHs can be accounted for by the previously proposed H-abstraction-C{sub 2}H{sub 2}-addiction mechanism.

  15. Isotope effect in normal-to-local transition of acetylene bending modes

    DOE PAGESBeta

    Ma, Jianyi; Xu, Dingguo; Guo, Hua; Tyng, Vivian; Kellman, Michael E.

    2012-01-01

    The normal-to-local transition for the bending modes of acetylene is considered a prelude to its isomerization to vinylidene. Here, such a transition in fully deuterated acetylene is investigated using a full-dimensional quantum model. It is found that the local benders emerge at much lower energies and bending quantum numbers than in the hydrogen isotopomer HCCH. This is accompanied by a transition to a second kind of bending mode called counter-rotator, again at lower energies and quantum numbers than in HCCH. These transitions are also investigated using bifurcation analysis of two empirical spectroscopic fitting Hamiltonians for pure bending modes, which helpsmore » to understand the origin of the transitions semiclassically as branchings or bifurcations out of the trans and normal bend modes when the latter become dynamically unstable. The results of the quantum model and the empirical bifurcation analysis are in very good agreement.« less

  16. Formation of Large Ag Clusters with Shells of Methane, Ethylene, and Acetylene in He Droplets.

    PubMed

    Loginov, Evgeny; Gomez, Luis F; Sartakov, Boris G; Vilesov, Andrey F

    2016-09-01

    Helium droplets were used to assemble composite metal-molecular clusters. Produced clusters have several hundreds of silver atoms in the core, immersed in a shell consisting of methane, ethylene, or acetylene molecules. The structure of the clusters was studied via infrared spectra of the C-H stretches of the hydrocarbon molecules. The spectra of the clusters containing methane and acetylene show two distinct features due to molecules on the interface with silver core and those in the volume of the neat molecular part of the clusters. The relative intensities of the peaks are in good agreement with the estimates based on the number of the captured particles. Experiments also suggest that selection rules for infrared transitions for molecules adsorbed on metal surfaces are also valid for silver clusters as small as 300 atoms. PMID:27500443

  17. Thermally and oxidatively stable carborane-siloxane-acetylenic-based thermosetting polymers

    SciTech Connect

    Henderson, L.J. Jr.; Keller, T.M.

    1993-12-31

    Inorganic-organic hybrid polymers that can be pyrolyzed to generate new ceramics are of current interest as a route to high temperature materials. Ceramics have desirable thermal stabilities, but are difficult to process. Inorganic-organic hybrid polymers as ceramic precursors combine organic`s ease of processability with inorganic`s desirable thermal and oxidative stability. Carborane-siloxane-acetylenic-based polymers are an application of this approach. The synthesis, characterization and thermooxidative properties of poly(butadiyne-1,7,bis(tetramethyldisiloxyl)-m-carborane) (polymer 2) is described. Polymer 2 is a viscous dark brown polymer that is soluble in most organic solvents making it was to process. Thermal crosslinking of acetylenic groups generates a thermoset which in turn can be pyrolyzed to ceramic material. Thermal and thermo-oxidative characterization is by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Cure studies of larger samples are also presented.

  18. The ozone acetylene reaction: concerted or non-concerted reaction mechanism? A quantum chemical investigation

    NASA Astrophysics Data System (ADS)

    Cremer, Dieter; Kraka, Elfi; Crehuet, Ramon; Anglada, Josep; Gräfenstein, Jürgen

    2001-10-01

    The ozone-acetylene reaction is found to proceed via an intermediate van der Waals complex (rather than a biradical), which is the precursor for a concerted symmetry-allowed [4+2] cycloaddition reaction leading to 1,2,3-trioxolene. CCSD(T)/6-311G+(2d, 2p) and CCSD(T)/CBS (complete basis set) calculations predict the ozone-acetylene van der Waals complex to be stable by 2.2 kcal mol -1, the calculated activation enthalpy for the cycloaddition reaction is 9.6 kcal mol -1 and the reaction enthalpy -55.5 kcal mol -1. Calculated kinetic data for the overall reaction ( k=0.8 l mol -1 s-1, A=1.71×10 6 l mol -1 s-1, E a=8.6 kcal mol -1) suggest that there is a need for refined kinetic measurements.

  19. Isotope effect in normal-to-local transition of acetylene bending modes

    SciTech Connect

    Ma, Jianyi; Xu, Dingguo; Guo, Hua; Tyng, Vivian; Kellman, Michael E.

    2012-01-01

    The normal-to-local transition for the bending modes of acetylene is considered a prelude to its isomerization to vinylidene. Here, such a transition in fully deuterated acetylene is investigated using a full-dimensional quantum model. It is found that the local benders emerge at much lower energies and bending quantum numbers than in the hydrogen isotopomer HCCH. This is accompanied by a transition to a second kind of bending mode called counter-rotator, again at lower energies and quantum numbers than in HCCH. These transitions are also investigated using bifurcation analysis of two empirical spectroscopic fitting Hamiltonians for pure bending modes, which helps to understand the origin of the transitions semiclassically as branchings or bifurcations out of the trans and normal bend modes when the latter become dynamically unstable. The results of the quantum model and the empirical bifurcation analysis are in very good agreement.

  20. Application of the photoacoustic method to the measurement of acetylene reduction by nitrogenase enzyme

    NASA Astrophysics Data System (ADS)

    Schramm, D. U.; Sthel, M. S.; Carneiro, L. O.; Franco, A. A.; Campos, A. C.; Vargas, H.

    2005-06-01

    Nitrogenase is an enzyme responsible for the reduction of the atmospheric N2 into NH4^+, which represents the key entry point of the molecular nitrogen into the biogeochemical cycle of nitrogen. This enzyme is present in the rhizobial bacteroids, which are symbionts in a Leguminosae plant (Acacia Holosericea), and also reduces acetylene into ethylene at the same rate as the nitrogen reduction. Therefore, a CO2 Laser Photoacoustic system was used for detecting and monitoring the ethylene emission by the nitrogenase activity, in the rhizobial symbionts in Acacia Holosericea, when they are confined in test tubes with acetylene at two different volumes (0.1 and 0.5 ml). Ethylene concentrations are also determined in the ppm range.

  1. Characterization of the Minimum Energy Paths and Energetics for the reaction of Vinylidene with Acetylene

    NASA Technical Reports Server (NTRS)

    Walch, Stephen P.; Taylor, Peter R.

    1995-01-01

    The reaction of vinylidene (CH2C) with acetylene may be an initiating reaction in soot formation. We report minimum energy paths and accurate energetics for a pathway leading to vinylacetylene and for a number of isomers Of C4H4. The calculations use complete active space self-consistent field (CASSCF) derivative methods to characterize the stationary points and internally contacted configuration interaction (ICCI) and/or coupled cluster singles and doubles with a perturbational estimate of triple excitations (CCSD(T)) to determine the energetics. We find an entrance channel barrier of about 5 kcal/mol for the addition of vinylidene to acetylene, but no barriers above reactants for the reaction pathway leading to vinylacetylene.

  2. Probing Ionic Complexes of Ethylene and Acetylene with Vacuum-Ultraviolet Radiation.

    PubMed

    Bandyopadhyay, Biswajit; Stein, Tamar; Fang, Yigang; Kostko, Oleg; White, Alec; Head-Gordon, Martin; Ahmed, Musahid

    2016-07-14

    Mixed complexes of acetylene-ethylene are studied using vacuum-ultraviolet (VUV) photoionization mass spectrometry and theoretical calculations. These complexes are produced and ionized at different distances from the exit of a continuous nozzle followed by reflectron time-of-flight mass spectrometry detection. Acetylene, with a higher ionization energy (11.4 eV) than ethylene (10.6 eV), allows for tuning the VUV energy and initializing reactions either from a C2H2(+) or a C2H4(+) cation. Pure acetylene and ethylene expansions are separately carried out to compare, contrast, and hence identify products from the mixed expansion: these are C3H3(+) (m/z = 39), C4H5(+) (m/z = 53), and C5H5(+) (m/z = 65). Intensity distributions of C2H2, C2H4, their dimers and reactions products are plotted as a function of ionization distance. These distributions suggest that association mechanisms play a crucial role in product formation closer to the nozzle. Photoionization efficiency (PIE) curves of the mixed complexes demonstrate rising edges closer to both ethylene and acetylene ionization energies. We use density functional theory (ωB97X-V/aug-cc-pVTZ) to study the structures of the neutral and ionized dimers, calculate their adiabatic and vertical ionization energies, as well as the energetics of different isomers on the potential energy surface (PES). Upon ionization, vibrationally excited clusters can use the extra energy to access different isomers on the PES. At farther ionization distances from the nozzle, where the number densities are lower, unimolecular decay is expected to be the dominant mechanism. We discuss the possible decay pathways from the different isomers on the PES and examine the ones that are energetically accessible. PMID:26983013

  3. A new C-10 acetylene and A new triterpenoid from Conyza canadensis.

    PubMed

    Xie, Wei Dong; Gao, Xue; Jia, Zhong Jian

    2007-05-01

    From the whole plants of Conyza canadensis (Compositae), a new C-10 acetylene, namely 8R, 9R-dihydroxymatricarine methyl ester (1), and a new triterpenoid, namely 3beta, 16beta, 20beta-trihydroxytaraxast-3-O-palmitoxyl ester (4), were isolated along with eleven known compounds (2, 3, 5-13). The structures of all 13 compounds were elucidated on the basis of their spectral data. The antibacterial activities of compounds 1-3 were evaluated. PMID:17615671

  4. Theoretical study of the C-H bond dissociation energy of acetylene

    NASA Technical Reports Server (NTRS)

    Taylor, Peter R.; Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.

    1990-01-01

    The authors present a theoretical study of the convergence of the C-H bond dissociation energy (D sub o) of acetylene with respect to both the one- and n-particle spaces. Their best estimate for D sub o of 130.1 plus or minus 1.0 kcal/mole is slightly below previous theoretical estimates, but substantially above the value determined using Stark anticrossing spectroscopy that is asserted to be an upper bound.

  5. IUPAC-NIST Solubility Data Series. 97. Solubility of Higher Acetylenes and Triple Bonded Derivatives

    NASA Astrophysics Data System (ADS)

    Fogg, Peter G. T.

    2013-03-01

    Solubility of Ethyne in Liquids was published in 2001 as Vol. 76 of the IUPAC-NIST Solubility Data Series. The current work extends the coverage to the solubility in liquids of higher gaseous and liquid acetylenes and to derivatives that contain a triple carbon-carbon bond. Predictive methods for estimating solubilities in water are summarised and usually give values to within an order of magnitude. The literature has been surveyed to the end of 2010.

  6. Burns from acetylene gas: more than skin deep

    PubMed Central

    Al-Hassani, Fawaz; Amin, Kavit; Lo, Steven

    2014-01-01

    Oxyacetylene welding torches are commonly used in industry, yet serious burns are fortunately rare. When dealing with the sequelae of these burn injuries, one must be aware of the high pressure component of these flame burns, which can penetrate and dissect the subcutaneous tissue. Appropriate initial assessment and preoperative planning are, therefore, essential to exclude and identify problems such as, compartment syndrome, subcutaneous emphysema and acute carpal tunnel syndrome. We present a case in which an innocuous palmar burn revealed a penetrating flame injury into the carpal tunnel. PMID:24842344

  7. Burns from acetylene gas: more than skin deep.

    PubMed

    Al-Hassani, Fawaz; Amin, Kavit; Lo, Steven

    2014-01-01

    Oxyacetylene welding torches are commonly used in industry, yet serious burns are fortunately rare. When dealing with the sequelae of these burn injuries, one must be aware of the high pressure component of these flame burns, which can penetrate and dissect the subcutaneous tissue. Appropriate initial assessment and preoperative planning are, therefore, essential to exclude and identify problems such as, compartment syndrome, subcutaneous emphysema and acute carpal tunnel syndrome. We present a case in which an innocuous palmar burn revealed a penetrating flame injury into the carpal tunnel. PMID:24842344

  8. Adsorption of acetic acid on ice studied by ambient-pressure XPS and partial-electron-yield NEXAFS spectroscopy at 230-240 K.

    PubMed

    Křepelová, Adéla; Bartels-Rausch, Thorsten; Brown, Matthew A; Bluhm, Hendrik; Ammann, Markus

    2013-01-17

    Ice plays a key role in the environment, and the ice-air interface influences heterogeneous chemical reactions between snowpack or cirrus clouds and the surrounding air. Soluble gases have been suspected to affect the topmost, disordered layer on ice (often referred to as a quasiliquid layer, QLL). Changes are especially expected in the hydrogen-bonding structure of water in the presence of solutes at the ice surface. Here, we used ambient-pressure X-ray photoelectron spectroscopy (XPS) to detect acetic acid at the ice surface at 230-240 K under atmospheric conditions for the first time. Electron-kinetic-energy-dependent C 1s spectra indicate that acetic acid remains confined to the topmost ice surface layers. Spectral analysis provides information about the protonation state of acetate at the ice surface. Surface-sensitive Auger-electron-yield C-edge near-edge X-ray absorption fine structure (NEXAFS) spectra were recorded to probe the molecular state of the adsorbed species. The O-edge NEXAFS spectra show only minor differences between clean ice and ice with adsorbed acetic acid and thus indicate that acetic acid does not lead to an extended disordered layer on the ice surface between 230 and 240 K. PMID:23252403

  9. Soluble fluorinated polyimides that contain curable acetylene units in the backbone

    SciTech Connect

    Takeichi, T.; Ogura, S.

    1993-12-31

    Soluble polyimides that contain internal acetylene groups in the backbone were prepared by reacting 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride with various ratio of bis(3-aminophenyl)acetylene and 4,4`-diaminodiphenyl ether. The polyimides were soluble in organic solvents such as N-methylpyrrolidone (NMP) and N,N-dimethylacetamide, and exhibited reduced viscosities in the range of 0.76-1.44 (in NMP at 30{degrees}C). The crosslinking behavior was examined by DSC. The onset of exotherm appeared at 321-345{degrees}C depending on the acetylene content. After thermal treatment at 350{degrees}C, the polyimides became insoluble in any organic solvents examined and in conc. sulfuric acid. The viscoelastic analyses showed the effect of crosslinking clearly. For example, Tg increased with thermal treatment, and was finally above 400{degrees}C. The drop of modulus at higher temperature also became very small. The TGA analyses also showed excellent thermal stability.

  10. Dehalogenative Homocoupling of Terminal Alkynyl Bromides on Au(111): Incorporation of Acetylenic Scaffolding into Surface Nanostructures.

    PubMed

    Sun, Qiang; Cai, Liangliang; Ma, Honghong; Yuan, Chunxue; Xu, Wei

    2016-07-26

    On-surface C-C coupling reactions of molecular precursors with alkynyl functional groups demonstrate great potential for the controllable fabrication of low-dimensional carbon nanostructures/nanomaterials, such as carbyne, graphyne, and graphdiyne, which demand the incorporation of highly active sp-hybridized carbons. Recently, through a dehydrogenative homocoupling reaction of alkynes, the possibility was presented to fabricate surface nanostructures involving acetylenic linkages, while problems lie in the fact that different byproducts are inevitably formed when triggering the reactions at elevated temperatures. In this work, by delicately designing the molecular precursors with terminal alkynyl bromide, we introduce the dehalogenative homocoupling reactions on the surface. As a result, we successfully achieve the formation of dimer structures, one-dimensional molecular wires and two-dimensional molecular networks with acetylenic scaffoldings on an inert Au(111) surface, where the unexpected C-Au-C organometallic intermediates are also observed. This study further supplements the database of on-surface dehalogenative C-C coupling reactions, and more importantly, it provides us an alternative efficient way for incorporating the acetylenic scaffolding into low-dimensional surface nanostructures. PMID:27326451

  11. Toward spectroscopically accurate global ab initio potential energy surface for the acetylene-vinylidene isomerization

    SciTech Connect

    Han, Huixian; Li, Anyang; Guo, Hua

    2014-12-28

    A new full-dimensional global potential energy surface (PES) for the acetylene-vinylidene isomerization on the ground (S{sub 0}) electronic state has been constructed by fitting ∼37 000 high-level ab initio points using the permutation invariant polynomial-neural network method with a root mean square error of 9.54 cm{sup −1}. The geometries and harmonic vibrational frequencies of acetylene, vinylidene, and all other stationary points (two distinct transition states and one secondary minimum in between) have been determined on this PES. Furthermore, acetylene vibrational energy levels have been calculated using the Lanczos algorithm with an exact (J = 0) Hamiltonian. The vibrational energies up to 12 700 cm{sup −1} above the zero-point energy are in excellent agreement with the experimentally derived effective Hamiltonians, suggesting that the PES is approaching spectroscopic accuracy. In addition, analyses of the wavefunctions confirm the experimentally observed emergence of the local bending and counter-rotational modes in the highly excited bending vibrational states. The reproduction of the experimentally derived effective Hamiltonians for highly excited bending states signals the coming of age for the ab initio based PES, which can now be trusted for studying the isomerization reaction.

  12. Discovery of acetylene hydratase activity of the iron–sulphur protein IspH

    PubMed Central

    Wang, Weixue; Zhang, Yonghui; Bacher, Adelbert; Eisenreich, Wolfgang; Li, Kai; Schulz, Charles; Oldfield, Eric; Groll, Michael

    2013-01-01

    The final step of the methylerythritol phosphate isoprenoid biosynthesis pathway is catalysed by the iron–sulphur enzyme IspH, producing the universal precursors of terpenes: isopentenyl diphosphate and dimethylallyl diphosphate. Here we report an unforeseen reaction discovered during the investigation of the interaction of IspH with acetylene inhibitors by X-ray crystallography, Mößbauer, and nuclear magnetic resonance spectroscopy. In addition to its role as a 2H+/2e− reductase, IspH can hydrate acetylenes to aldehydes and ketones via anti-Markovnikov/Markovnikov addition. The reactions only occur with the oxidised protein and proceed via η1-O-enolate intermediates. One of these is characterized crystallographically and contains a C4 ligand oxygen bound to the unique, fourth iron in the 4Fe-4S cluster: this intermediate subsequently hydrolyzes to produce an aldehyde product. This unexpected side to IspH reactivity is of interest in the context of the mechanism of action of other acetylene hydratases, as well as in the design of antiinfectives targeting IspH. PMID:22948824

  13. New insights into the anion formation mechanisms in dusty acetylene discharges

    NASA Astrophysics Data System (ADS)

    Mao, Ming; Benedikt, Jan; Consoli, Angelo; Bogaerts, Annemie

    2008-10-01

    Dust (or nanoparticle) formation is a well-known phenomenon occurring in reactive gas plasmas, such as silane or acetylene. Under some conditions, the dust formation is considered to be harmful, whereas for other applications, it turns out to be beneficial. In this presentation, the initial mechanisms of nanoparticle formation and growth in radiofrequency (RF) acetylene (C2H2) plasmas are investigated by means of a comprehensive self-consistent one-dimensional (1D) fluid model. Based on the comparison of our calculation results with available experimental data for acetylene plasmas in the literature, some new mechanisms for negative ion formation and growth are proposed. Possible routes are considered for the formation of larger (linear and branched) hydrocarbons C2nH2 (n=3-5), which contribute to the generation of C2nH^-anions (n=3-5) due to dissociative electron attachment. Moreover, beside the C2nH^- ions, also the vinylidene anion (H2CC^-) and higher C2nH2^- anions (n=2-4) are found to be important plasma species. This project was supported financially by the Fund for Scientific Research (FWO) Flanders (Project G. 0068.07), the Interuniversity Attraction Poles Programme of the Belgian State (Belgian Science Policy; Project P6/42) and the CALCUA computing facilities of the University of Antwerp.

  14. Proton uptake in the H(+)-SOFC cathode material Ba(0.5)Sr(0.5)Fe(0.8)Zn(0.2)O(3-δ): transition from hydration to hydrogenation with increasing oxygen partial pressure.

    PubMed

    Poetzsch, Daniel; Merkle, Rotraut; Maier, Joachim

    2015-01-01

    Thermogravimetric investigations on the perovskite Ba(0.5)Sr(0.5)Fe(0.8)Zn(0.2)O(3-δ) (BSFZ, with mixed hole, oxygen vacancy and proton conductivity) from water vapor can occur by acid-base reaction (hydration) or redox reaction (hydrogen uptake), depending on the oxygen partial pressure, i.e. on the material's defect concentrations. In parallel, the effective diffusion coefficient of the stoichiometry relaxation kinetics also changes. These striking observations can be rationalized in terms of a defect chemical model and transport equations for materials with three mobile carriers. Implications for the search of cathode materials with mixed electronic and protonic conductivity for application on proton conducting oxide electrolytes are discussed. PMID:26206522

  15. The role of AsH3 partial pressure on anti-phase boundary in GaAs-on-Ge grown by MOCVD - Application to a 200 mm GaAs virtual substrate

    NASA Astrophysics Data System (ADS)

    Kohen, David; Bao, Shuyu; Lee, Kwang Hong; Lee, Kenneth Eng Kian; Tan, Chuan Seng; Yoon, Soon Fatt; Fitzgerald, Eugene A.

    2015-07-01

    We demonstrate the influence of the arsine partial pressure (p(AsH3)) on the quality of a GaAs layer grown on Ge substrate by metal organic chemical vapor deposition. The GaAs quality improves with p(AsH3) used during the 100 nm thick GaAs buffer layer. By growing a GaAs buffer layer at 630 °C with p(AsH3) of 5 mbar, we obtain a smooth GaAs layer with a root mean square roughness of 4.7 Å. This GaAs layer does not contain anti-phase boundaries. With these optimized growth parameters, we fabricate a virtual GaAs substrate on a 200 mm silicon wafer as a first step towards the integration of III-V devices on silicon.

  16. Acetylene from the co-pyrolysis of biomass and waste tires or coal in the H{sub 2}/Ar plasma

    SciTech Connect

    Bao, W.; Cao, Q.; Lv, Y.; Chang, L.

    2008-07-01

    Acetylene from carbon-containing materials via plasma pyrolysis is not only simple but also environmentally friendly. In this article, the acetylene produced from co-pyrolyzing biomass with waste tire or coal under the conditions of H{sub 2}/Ar DC arc plasma jet was investigated. The experimental results showed that the co-pyrolysis of mixture with biomass and waste tire or coal can improve largely the acetylene relative volume fraction (RVF) in gaseous products and the corresponding yield of acetylene. The change trends for the acetylene yield of plasma pyrolysis from mixture with raw sample properties were the same as relevant RVF. But the yield change trend with feeding rate is different from its RVF. The effects of the feeding rate of raw materials and the electric current of plasmatron on acetylene formation are also discussed.

  17. The anomalous behavior of the Zeeman anticrossing spectra of à 1Au acetylene: Theoretical considerations

    NASA Astrophysics Data System (ADS)

    Vacek, George; Sherrill, C. David; Yamaguchi, Yukio; Schaefer, Henry F., III

    1996-02-01

    P. Dupré, R. Jost, M. Lombardi, P. G. Green, E. Abramson, and R. W. Field have observed anomalous behavior of the anticrossing density in the Zeeman anticrossing (ZAC) spectra of gas phase à 1Au acetylene in the 42 200 to 45 300 cm-1 energy range. To best explain this result, they hypothesize a large singlet-triplet coupling due to the existence of a linear isomerization barrier connecting a triplet-excited cis- and trans-acetylene in the vicinity of the studied energy range (˜45 500 cm-1). Theoretically such a linear stationary point, however, must have two different degenerate bending vibrational frequencies which are either imaginary or exactly zero. Neither case has yet been experimentally detected. Here, we have studied the two lowest-lying linear triplet-excited-state stationary points of acetylene, 3Σ+u and 3Δu, to see if they fit Dupré et al.'s hypothesis. We have completed geometry optimization and harmonic vibrational frequency analysis using complete-active-space self-consistent field (CASSCF) wave functions as well as determined energy points at those geometries using the second-order configuration interaction (SOCI) method. Harmonic vibrational analyses of both stationary points reveal two different doubly degenerate vibrational modes with imaginary vibrational frequencies (or negative force constants) indicating that they are indeed saddle points with a Hessian index of four. At the DZP SOCI//CASSCF level of theory with zero-point vibrational energy (ZPVE) correction, the 3Σ+u stationary point lies 35 840 cm-1 above the ground state of acetylene. This is much too low in energy to contribute to the ZAC spectral anomaly. At the same level of theory with ZPVE correction, the 3Δu stationary point lies 44 940 cm-1 above the ground state consistent with Dupré et al.'s hypothesis. Several solutions to the anomalous ZAC spectra are discussed. We propose that the anomaly may also be due to coupling with a nearly linear structure on the T3 surface of

  18. Interpretation of PAN, acetone and acetylene measurements from the MIPAS-E

    NASA Astrophysics Data System (ADS)

    Moore, D. P.; Remedios, J. J.; Parker, R. J.

    2009-04-01

    Emissions of anthropogenic pollution, from biomass burning events in particular, result in the injection of a wide range of carbon compounds into the atmosphere. Carbon monoxide (CO), methane (CH4) and volatile organic compounds (VOCs) are released in significant amounts, affecting both the oxidation capacity of the troposphere and ozone production. Upper troposphere (UT) measurements of PAN, acetone and acetylene have, in the past, been generally limited to sporadic in situ sampling during specialised campaign periods. The recent rapid progress in both the detection and retrieval of many VOC species from spaceborne instrumentation has been large. It has recently been established that the observation of the global distribution of VOCs in the UT can be made by measurements provided by instruments such as the Michelson Interferometer for Passive Atmospheric Sounding onboard ENVISAT (MIPAS-E) or the Atmospheric Chemistry Experiment (ACE) onboard SCISAT-1. In this work, we discuss the ability of MIPAS-E to provide new global measurements of acetone in the UT. We also describe both the distribution and seasonality observed in UT PAN volume mixing ratios (vmrs). From the MIPAS-E acetylene measurements, we analyse the extent and magnitude of the chemical isolation observed over the Middle East during August 2003. We show that this enhancement is due to fast westward transport from Asia via the Easterly Jet associated with the Asian monsoon anticyclone. A full error analysis is carried out for each of the three gases we analyse. Previous work has shown that characteristic infrared signatures of PAN, acetone and acetylene can be detected in MIPAS-E thermal emission spectra, with the 787-790 cm-1, 1216-1218 cm-1 and 776.0-776.15 cm-1 spectral ranges respectively being particularly sensitive to changes in each of the gases. We invert the measured MIPAS-E spectra into vmrs using an independent offline-retrieval scheme based on the optimal estimation approach which was

  19. High-resolution photoemission study of acetylene adsorption and reaction with the Si(100)-2x1 surface

    SciTech Connect

    Xu, S.H.; Yang, Y.; Keeffe, M.; Lapeyre, G.J.; Rotenberg, E.

    1999-02-09

    The adsorption and reaction of acetylene with the Si{approximately}100-231 surface has been studied using high-resolution photoemission by monitoring the Si 2p,C 1s, and valence-band (VB) spectra as a function of both acetylene coverage and post-adsorption annealing temperature. After the clean Si(100) surface is exposed to 0.5 monolayer (ML) acetylene, the surface state in the VB is absent. Meanwhile, the curve-fitting results show that there is only one interface component in the Si 2p core level. These results indicate that the asymmetric Si dimers may become symmetric dimers after acetylene adsorption, which can be explained well by the tetra-sigma model determined from our previous photoelectron holographic results. Significant changes in the electronic structure (Si 2p,C 1s, and VB) are found after subsequent annealing of the saturation overlayer. Annealing at lower temperature can induce some acetylene molecule desorption while most of the molecules decompose into C2Hx (x=1,0) and H species. After annealing above 660C, both of the reacted components of the Si 2p and C 1s lines show that the SiC species form clusterlike features. At the same time, the VB and Si 2p spectra indicate a restoration of a Si(100)-2x1 structure, and the asymmetric Si dimers reappear on the surface.

  20. Rotational spectroscopy and molecular structure of the 1-chloro-1-fluoroethylene-acetylene complex.

    PubMed

    Leung, Helen O; Marshall, Mark D; Grimes, David D

    2011-01-21

    Guided by ab initio calculations, Fourier transform microwave spectra in the 6-21 GHz region are obtained for seven isotopomers of the complex formed between 1-chloro-1-fluoroethylene and acetylene. These include the four possible combinations of (35)Cl- and (37)Cl-containing CH(2)CClF with the most abundant acetylene isotopic modification, HCCH, and its H(13)C(13)CH analogue, as well as three singly substituted deuterated isotopomers. Analysis of the spectra determines the rotational constants and additionally, the complete chlorine quadrupole hyperfine coupling tensors in both the inertial and principal electric field gradient axis systems, and where appropriate, the diagonal components of the deuterium quadrupole coupling tensors. The inertial information contained in the rotational constants provides the structure for CH(2)CClF-HCCH: a primary, hydrogen bonding interaction existing between the HCCH donor and the F atom acceptor on the 1-chloro-1-fluoroethylene moiety, while a secondary interaction occurs between the acetylenic bond on the HCCH molecule and the H atom cis to the hydrogen-bonded F atom on the substituted ethylene, which causes the hydrogen bond to deviate from linearity. This is similar to the structure obtained for 1,1-difluoroethylene-HCCH [H. O. Leung and M. D. Marshall, J. Chem. Phys. 126, 154301 (2006)], and indeed, to within experimental uncertainty, the intermolecular interactions in CH(2)CClF-HCCH and its 1,1-difluoroethylene counterpart are practically indistinguishable, even though ab initio calculations at the MP2∕6-311G++(2d, 2p) level suggest that the former complex is more strongly bound. PMID:21261349