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Sample records for hydrogen atmosphere issledovanie

  1. An archetype hydrogen atmosphere problem

    NASA Technical Reports Server (NTRS)

    Athay, R. G.; Mihalas, D.; Shine, R. A.

    1975-01-01

    Populations for the first three bound states and the continuum of hydrogen are determined for an isothermal hydrostatic atmosphere at 20,000 K. The atmosphere is treated as optically thin in the Balmer and Paschen continua and illuminated by continuum radiation at these wavelengths with prescribed radiation temperatures. The atmosphere is optically thick in the 2-1, 3-1, 3-2 and c-1 transitions. Three stages of approximation are treated: (1) radiative detailed balance in the 2-1, 3-1 and 3-2 transitions, (2) radiative detailed balance in the 3-1 and 3-2 transitions, and (3) all transitions out of detailed balance. The solution of this problem is nontrivial and presents sufficient difficulty to have caused the failure of at least one rather standard technique. The problem is thus a good archetype against which new methods or new implementations of old methods may be tested.

  2. Atmospheric chemistry of hydrogen fluoride

    SciTech Connect

    Cheng, Meng -Dawn

    2017-04-11

    In this study, the atmospheric chemistry, emissions, and surface boundary layer transport of hydrogen fluoride (HF) is summarized. Although HF is known to be chemically reactive and highly soluble, both factors affect transport and removal in the atmosphere, we suggest that the chemistry can be ignored when the HF concentration is at a sufficiently low level (e.g., 10 ppmv). At a low concentration, the capability for HF to react in the atmosphere is diminished and therefore the species can be mathematically treated as inert during the transport. At a sufficiently high concentration of HF (e.g., kg/s release rate and thousandsmore » of ppm), however, HF can go through a series of rigorous chemical reactions including polymerization, depolymerization, and reaction with water to form molecular complex. As such, the HF species cannot be considered as inert because the reactions could intimately influence the plume s thermodynamic properties affecting the changes in plume temperature and density. The atmospheric residence time of HF was found to be less than four (4) days, and deposition (i.e., atmosphere to surface transport) is the dominant mechanism that controls the removal of HF and its oligomers from the atmosphere. The literature data on HF dry deposition velocity was relatively high compared to many commonly found atmospheric species such as ozone, sulfur dioxide, nitrogen oxides, etc. The global average of wet deposition velocity of HF was found to be zero based on one literature source. Uptake of HF by rain drops is limited by the acidity of the rain drops, and atmospheric particulate matter contributes negligibly to HF uptake. Finally, given that the reactivity of HF at a high release rate and elevated mole concentration cannot be ignored, it is important to incorporate the reaction chemistry in the near-field dispersion close to the proximity of the release source, and to incorporate the deposition mechanism in the far-field dispersion away from the

  3. A hydrogen-rich early Earth atmosphere.

    PubMed

    Tian, Feng; Toon, Owen B; Pavlov, Alexander A; De Sterck, H

    2005-05-13

    We show that the escape of hydrogen from early Earth's atmosphere likely occurred at rates slower by two orders of magnitude than previously thought. The balance between slow hydrogen escape and volcanic outgassing could have maintained a hydrogen mixing ratio of more than 30%. The production of prebiotic organic compounds in such an atmosphere would have been more efficient than either exogenous delivery or synthesis in hydrothermal systems. The organic soup in the oceans and ponds on early Earth would have been a more favorable place for the origin of life than previously thought.

  4. Isotopic composition of atmospheric hydrogen and methane

    USGS Publications Warehouse

    Bainbridge, A.E.; Suess, H.E.; Friedman, I.

    1961-01-01

    IN a recent communication, Bishop and Taylor1 express the opinion that the tritium concentration of free hydrogen in the atmosphere has been rising over the past ten years, with a doubling time of approximately 18 months. The authors suspect that artificial tritium was released into the atmosphere several years before the Castle test series in 1954, which is commonly assumed to have led to the first pronounced rise in the tritium concentration of terrestrial surface water. Bishop and Taylor's communication includes a diagram of the logarithms of all the experimentally determined tritium values in free atmospheric hydrogen plotted against time. The plot shows that the values follow a straight line that includes the first value obtained by Faltings and Harteck2 on atmospheric hydrogen collected in 1948. ?? 1961 Nature Publishing Group.

  5. Atomic hydrogen distribution. [in Titan atmospheric model

    NASA Technical Reports Server (NTRS)

    Tabarie, N.

    1974-01-01

    Several possible H2 vertical distributions in Titan's atmosphere are considered with the constraint of 5 km-A a total quantity. Approximative calculations show that hydrogen distribution is quite sensitive to two other parameters of Titan's atmosphere: the temperature and the presence of other constituents. The escape fluxes of H and H2 are also estimated as well as the consequent distributions trapped in the Saturnian system.

  6. Atmospheric Hydrogen Scavenging: from Enzymes to Ecosystems

    PubMed Central

    Constant, Philippe; Hards, Kiel; Morales, Sergio E.; Oakeshott, John G.; Russell, Robyn J.; Taylor, Matthew C.; Berney, Michael; Conrad, Ralf; Cook, Gregory M.

    2014-01-01

    We have known for 40 years that soils can consume the trace amounts of molecular hydrogen (H2) found in the Earth's atmosphere. This process is predicted to be the most significant term in the global hydrogen cycle. However, the organisms and enzymes responsible for this process were only recently identified. Pure culture experiments demonstrated that several species of Actinobacteria, including streptomycetes and mycobacteria, can couple the oxidation of atmospheric H2 to the reduction of ambient O2. A combination of genetic, biochemical, and phenotypic studies suggest that these organisms primarily use this fuel source to sustain electron input into the respiratory chain during energy starvation. This process is mediated by a specialized enzyme, the group 5 [NiFe]-hydrogenase, which is unusual for its high affinity, oxygen insensitivity, and thermostability. Atmospheric hydrogen scavenging is a particularly dependable mode of energy generation, given both the ubiquity of the substrate and the stress tolerance of its catalyst. This minireview summarizes the recent progress in understanding how and why certain organisms scavenge atmospheric H2. In addition, it provides insight into the wider significance of hydrogen scavenging in global H2 cycling and soil microbial ecology. PMID:25501483

  7. Atmospheric hydrogen scavenging: from enzymes to ecosystems.

    PubMed

    Greening, Chris; Constant, Philippe; Hards, Kiel; Morales, Sergio E; Oakeshott, John G; Russell, Robyn J; Taylor, Matthew C; Berney, Michael; Conrad, Ralf; Cook, Gregory M

    2015-02-01

    We have known for 40 years that soils can consume the trace amounts of molecular hydrogen (H2) found in the Earth’s atmosphere.This process is predicted to be the most significant term in the global hydrogen cycle. However, the organisms and enzymes responsible for this process were only recently identified. Pure culture experiments demonstrated that several species of Actinobacteria, including streptomycetes and mycobacteria, can couple the oxidation of atmospheric H2 to the reduction of ambient O2. A combination of genetic, biochemical, and phenotypic studies suggest that these organisms primarily use this fuel source to sustain electron input into the respiratory chain during energy starvation. This process is mediated by a specialized enzyme, the group 5 [NiFe]-hydrogenase, which is unusual for its high affinity, oxygen insensitivity, and thermostability. Atmospheric hydrogen scavenging is a particularly dependable mode of energy generation, given both the ubiquity of the substrate and the stress tolerance of its catalyst. This minireview summarizes the recent progress in understanding how and why certain organisms scavenge atmospheric H2. In addition, it provides insight into the wider significance of hydrogen scavenging in global H2 cycling and soil microbial ecology.

  8. Photosynthesis in hydrogen-dominated atmospheres.

    PubMed

    Bains, William; Seager, Sara; Zsom, Andras

    2014-11-18

    The diversity of extrasolar planets discovered in the last decade shows that we should not be constrained to look for life in environments similar to early or present-day Earth. Super-Earth exoplanets are being discovered with increasing frequency, and some will be able to retain a stable, hydrogen-dominated atmosphere. We explore the possibilities for photosynthesis on a rocky planet with a thin H2-dominated atmosphere. If a rocky, H2-dominated planet harbors life, then that life is likely to convert atmospheric carbon into methane. Outgassing may also build an atmosphere in which methane is the principal carbon species. We describe the possible chemical routes for photosynthesis starting from methane and show that less energy and lower energy photons could drive CH4-based photosynthesis as compared with CO2-based photosynthesis. We find that a by-product biosignature gas is likely to be H2, which is not distinct from the hydrogen already present in the environment. Ammonia is a potential biosignature gas of hydrogenic photosynthesis that is unlikely to be generated abiologically. We suggest that the evolution of methane-based photosynthesis is at least as likely as the evolution of anoxygenic photosynthesis on Earth and may support the evolution of complex life.

  9. Photosynthesis in Hydrogen-Dominated Atmospheres

    PubMed Central

    Bains, William; Seager, Sara; Zsom, Andras

    2014-01-01

    The diversity of extrasolar planets discovered in the last decade shows that we should not be constrained to look for life in environments similar to early or present-day Earth. Super-Earth exoplanets are being discovered with increasing frequency, and some will be able to retain a stable, hydrogen-dominated atmosphere. We explore the possibilities for photosynthesis on a rocky planet with a thin H2-dominated atmosphere. If a rocky, H2-dominated planet harbors life, then that life is likely to convert atmospheric carbon into methane. Outgassing may also build an atmosphere in which methane is the principal carbon species. We describe the possible chemical routes for photosynthesis starting from methane and show that less energy and lower energy photons could drive CH4-based photosynthesis as compared with CO2-based photosynthesis. We find that a by-product biosignature gas is likely to be H2, which is not distinct from the hydrogen already present in the environment. Ammonia is a potential biosignature gas of hydrogenic photosynthesis that is unlikely to be generated abiologically. We suggest that the evolution of methane-based photosynthesis is at least as likely as the evolution of anoxygenic photosynthesis on Earth and may support the evolution of complex life. PMID:25411926

  10. Hydrogen peroxide measurements in the marine atmosphere

    NASA Astrophysics Data System (ADS)

    Jacob, P.; Klockow, D.

    1992-11-01

    Hydrogen peroxide, one of the key compounds in multiphase atmospheric chemistry, was measured on an Atlantic cruise (ANT VII/1) of the German research vessel Polarstern from 15 September to 9 October 1988, in rain and ambient air by a chemiluminescence technique. For gas-phase H2O2 cryogenic sampling was employed. The presented results show an increase of gas-phase mixing ratios of about 45 pptv per degree latitude between 50 deg N and 0 deg, and a maximum of 3.5 ppbv around the equator. Generally higher mixing ratios were observed in the Southern Hemisphere, with a clear diurnal variation. The H2O2 mixing ratio is correlated to the UV radiation intensity and to the temperature difference between air and ocean surface water.

  11. Innovative Monitoring of Atmospheric Gaseous Hydrogen Fluoride

    PubMed Central

    Bonari, Alessandro; Pompilio, Ilenia; Monti, Alessandro; Arcangeli, Giulio

    2016-01-01

    Hydrogen fluoride (HF) is a basic raw material for a wide variety of industrial products, with a worldwide production capacity of more than three million metric tonnes. A novel method for determining particulate fluoride and gaseous hydrogen fluoride in air is presented herewith. Air was sampled using miniaturised 13 mm Swinnex two-stage filter holders in a medium-flow pumping system and through the absorption of particulate fluoride and HF vapours on cellulose ester filters uncoated or impregnated with sodium carbonate. Furthermore, filter desorption from the holders and the extraction of the pentafluorobenzyl ester derivative based on solid-phase microextraction were performed using an innovative robotic system installed on an xyz autosampler on-line with gas chromatography (GC)/mass spectrometry (MS). After generating atmospheres of a known concentration of gaseous HF, we evaluated the agreement between the results of our sampling method and those of the conventional preassembled 37 mm cassette (±8.10%; correlation coefficient: 0.90). In addition, precision (relative standard deviation for n = 10, 4.3%), sensitivity (0.2 μg/filter), and linearity (2.0–4000 μg/filter; correlation coefficient: 0.9913) were also evaluated. This procedure combines the efficiency of GC/MS systems with the high throughput (96 samples/day) and the quantitative accuracy of pentafluorobenzyl bromide on-sample derivatisation. PMID:27829835

  12. Innovative Monitoring of Atmospheric Gaseous Hydrogen Fluoride.

    PubMed

    Dugheri, Stefano; Bonari, Alessandro; Pompilio, Ilenia; Monti, Alessandro; Mucci, Nicola; Arcangeli, Giulio

    2016-01-01

    Hydrogen fluoride (HF) is a basic raw material for a wide variety of industrial products, with a worldwide production capacity of more than three million metric tonnes. A novel method for determining particulate fluoride and gaseous hydrogen fluoride in air is presented herewith. Air was sampled using miniaturised 13 mm Swinnex two-stage filter holders in a medium-flow pumping system and through the absorption of particulate fluoride and HF vapours on cellulose ester filters uncoated or impregnated with sodium carbonate. Furthermore, filter desorption from the holders and the extraction of the pentafluorobenzyl ester derivative based on solid-phase microextraction were performed using an innovative robotic system installed on an xyz autosampler on-line with gas chromatography (GC)/mass spectrometry (MS). After generating atmospheres of a known concentration of gaseous HF, we evaluated the agreement between the results of our sampling method and those of the conventional preassembled 37 mm cassette (±8.10%; correlation coefficient: 0.90). In addition, precision (relative standard deviation for n = 10, 4.3%), sensitivity (0.2  μ g/filter), and linearity (2.0-4000  μ g/filter; correlation coefficient: 0.9913) were also evaluated. This procedure combines the efficiency of GC/MS systems with the high throughput (96 samples/day) and the quantitative accuracy of pentafluorobenzyl bromide on-sample derivatisation.

  13. Comment on "A hydrogen-rich early Earth atmosphere".

    PubMed

    Catling, David C

    2006-01-06

    Tian et al. (Reports, 13 May 2005, p. 1014) proposed a hydrogen-rich early atmosphere with slow hydrogen escape from a cold thermosphere. However, their model neglects the ultraviolet absorption of all gases other than H2. The model also neglects Earth's magnetic field, which affects the temperature and density of ions and promotes nonthermal escape of neutral hydrogen.

  14. The potential impact of hydrogen energy use on the atmosphere

    NASA Astrophysics Data System (ADS)

    van Ruijven, B. J.; Lamarque, J. F.; van Vuuren, D. P.; Kram, T.; Eerens, H.

    2009-04-01

    Energy models show very different trajectories for future energy systems (partly as function of future climate policy). One possible option is a transition towards a hydrogen-based energy system. The potential impact of such hydrogen economy on atmospheric emissions is highly uncertain. On the one hand, application of hydrogen in clean fuel cells reduces emissions of local air pollutants, like SOx and NOx. On the other hand, emissions of hydrogen from system leakages are expected to change the atmospheric concentrations and behaviour (see also Price et al., 2007; Sanderson et al., 2003; Schultz et al., 2003; Tromp et al., 2003). The uncertainty arises from several sources: the expected use of hydrogen, the intensity of leakages and emissions, and the atmospheric chemical behaviour of hydrogen. Existing studies to the potential impacts of a hydrogen economy on the atmosphere mostly use hydrogen emission scenarios that are based on simple assumptions. This research combines two different modelling efforts to explore the range of impacts of hydrogen on atmospheric chemistry. First, the potential role of hydrogen in the global energy system and the related emissions of hydrogen and other air pollutants are derived from the global energy system simulation model TIMER (van Vuuren, 2007). A set of dedicated scenarios on hydrogen technology development explores the most pessimistic and optimistic cases for hydrogen deployment (van Ruijven et al., 2008; van Ruijven et al., 2007). These scenarios are combined with different assumptions on hydrogen emission factors. Second, the emissions from the TIMER model are linked to the NCAR atmospheric model (Lamarque et al., 2005; Lamarque et al., 2008), in order to determine the impacts on atmospheric chemistry. By combining an energy system model and an atmospheric model, we are able to consistently explore the boundaries of both hydrogen use, emissions and impacts on atmospheric chemistry. References: Lamarque, J.-F., Kiehl, J. T

  15. Study of properties of tungsten irradiated in hydrogen atmosphere

    NASA Astrophysics Data System (ADS)

    Tazhibayeva, I.; Skakov, M.; Baklanov, V.; Koyanbayev, E.; Miniyazov, A.; Kulsartov, T.; Ponkratov, Yu.; Gordienko, Yu.; Zaurbekova, Zh.; Kukushkin, I.; Nesterov, E.

    2017-12-01

    The paper presents the results of the experiments with DF (double forged) tungsten samples irradiated at the WWR-K research reactor in hydrogen and helium atmospheres. The irradiation time was 3255 h (135.6 d). After reactor irradiation, W samples have been subjected to investigations of their activity level, hardness, and microstructure, as well as x-ray and texture observations. The hydrogen yield released from irradiated tungsten samples have been measured using TDS-method. The hydrogen concentration in the tungsten samples irradiated in hydrogen was higher than that in the samples irradiated in helium atmosphere. It is shown that the surface microstructure of tungsten samples irradiated in hydrogen is characterized by micro-pits, inclusions and blisters in the form of bubbles, which were not observed earlier for tungsten irradiated in hydrogen.

  16. Atomic hydrogen and nitrogen distributions from atmosphere explorer measurements

    NASA Technical Reports Server (NTRS)

    Breig, Edward L.

    1992-01-01

    We were selective as to our approach to research activities, and devoted primary attention to two investigations concerning the global behavior of atomic hydrogen in the Earth's upper atmosphere. We derive the thermospheric concentration of H by applying the condition of charge-exchange equilibrium between hydrogen and oxygen atoms and ions to in-situ measurements of F-region composition and temperature from the series of Atmosphere Explorer (AE) aeronomy satellites. Progress and accomplishments on these chosen research projects are summarized.

  17. Hydrogen Bonding Interaction between Atmospheric Gaseous Amides and Methanol.

    PubMed

    Zhao, Hailiang; Tang, Shanshan; Xu, Xiang; Du, Lin

    2016-12-30

    Amides are important atmospheric organic-nitrogen compounds. Hydrogen bonded complexes of methanol (MeOH) with amides (formamide, N -methylformamide, N , N -dimethylformamide, acetamide, N -methylacetamide and N , N -dimethylacetamide) have been investigated. The carbonyl oxygen of the amides behaves as a hydrogen bond acceptor and the NH group of the amides acts as a hydrogen bond donor. The dominant hydrogen bonding interaction occurs between the carbonyl oxygen and the OH group of methanol as well as the interaction between the NH group of amides and the oxygen of methanol. However, the hydrogen bonds between the CH group and the carbonyl oxygen or the oxygen of methanol are also important for the overall stability of the complexes. Comparable red shifts of the C=O, NH- and OH-stretching transitions were found in these MeOH-amide complexes with considerable intensity enhancement. Topological analysis shows that the electron density at the bond critical points of the complexes fall in the range of hydrogen bonding criteria, and the Laplacian of charge density of the O-H∙∙∙O hydrogen bond slightly exceeds the upper value of the Laplacian criteria. The energy decomposition analysis further suggests that the hydrogen bonding interaction energies can be mainly attributed to the electrostatic, exchange and dispersion components.

  18. Hydrogen Bonding Interaction between Atmospheric Gaseous Amides and Methanol

    PubMed Central

    Zhao, Hailiang; Tang, Shanshan; Xu, Xiang; Du, Lin

    2016-01-01

    Amides are important atmospheric organic–nitrogen compounds. Hydrogen bonded complexes of methanol (MeOH) with amides (formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide and N,N-dimethylacetamide) have been investigated. The carbonyl oxygen of the amides behaves as a hydrogen bond acceptor and the NH group of the amides acts as a hydrogen bond donor. The dominant hydrogen bonding interaction occurs between the carbonyl oxygen and the OH group of methanol as well as the interaction between the NH group of amides and the oxygen of methanol. However, the hydrogen bonds between the CH group and the carbonyl oxygen or the oxygen of methanol are also important for the overall stability of the complexes. Comparable red shifts of the C=O, NH- and OH-stretching transitions were found in these MeOH–amide complexes with considerable intensity enhancement. Topological analysis shows that the electron density at the bond critical points of the complexes fall in the range of hydrogen bonding criteria, and the Laplacian of charge density of the O–H∙∙∙O hydrogen bond slightly exceeds the upper value of the Laplacian criteria. The energy decomposition analysis further suggests that the hydrogen bonding interaction energies can be mainly attributed to the electrostatic, exchange and dispersion components. PMID:28042825

  19. Hydrogen-atmosphere induction furnace has increased temperature range

    NASA Technical Reports Server (NTRS)

    Caves, R. M.; Gresslin, C. H.

    1966-01-01

    Improved hydrogen-atmosphere induction furnace operates at temperatures up to 5,350 deg F. The furnace heats up from room temperature to 4,750 deg F in 30 seconds and cools down to room temperature in 2 minutes.

  20. Stable Hydrogen-rich Atmospheres of Young Rocky Planets

    NASA Astrophysics Data System (ADS)

    Zahnle, K. J.; Catling, D. C.; Gacesa, M.

    2016-12-01

    SourceURL:file://localhost/Volumes/Lexar/Zahnle_AGU_2016.docx Understanding hydrogen escape is essential to understanding the limits to habitability, both for liquid water where the Sun is bright, but also to assess the true potential of H2 as a greenhouse gas where the Sun is faint. Hydrogen-rich primary atmospheres of Earth-like planets can result either from gravitational capture of solar nebular gases (with helium), or from impact shock processing of a wide variety of volatile-rich planetesimals (typically accompanied by H2O, CO2, and under the right circumstances, CH4). Most studies of hydrogen escape from planets focus on determining how fast the hydrogen escapes. In general this requires solving hydrodynamic equations that take into account the acceleration of hydrogen through a critical transonic point and an energy budget that should include radiative heating and cooling, thermal conduction, the work done in lifting the hydrogen against gravity, and the residual heat carried by the hydrogen as it leaves. But for planets from which hydrogen escape is modest or insignificant, the atmosphere can be approximated as hydrostatic, which is much simpler, and for which a relatively full-featured treatment of radiative cooling by embedded molecules, atoms, and ions such as CO2 and H3+ is straightforward. Previous work has overlooked the fact that the H2 molecule is extremely efficient at exciting non-LTE CO2 15 micron emission, and thus that radiative cooling can be markedly more efficient when H2 is abundant. We map out the region of phase space in which terrestrial planets keep hydrogen-rich atmospheres, which is what we actually want to know for habitability. We will use this framework to reassess Tian et al's (Science 308, pp. 1014-1017, 2005) hypothesis that H2-rich atmospheres may have been rather long-lived on Earth itself. Finally, we will address the empirical observation that rocky planets with thin or negligible atmospheres are rarely or never bigger than

  1. Para hydrogen equilibration in the atmospheres of the outer planets

    NASA Technical Reports Server (NTRS)

    Conrath, Barney J.

    1986-01-01

    The thermodynamic behavior of the atmospheres of the Jovian planets is strongly dependent on the extent to which local thermal equilibration of the ortho and para states of molecular hydrogen is achieved. Voyager IRIS data from Jupiter imply substantial departures of the para hydrogen fraction from equilibrium in the upper troposphere at low latitudes, but with values approaching equilibrium at higher latitudes. Data from Saturn are less sensitive to the orth-para ratio, but suggest para hydrogen fractions near the equilibrium value. Above approximately the 200 K temperature level, para hydrogen conversion can enhance the efficiency of convection, resulting in a substantial increase in overturning times on all of the outer planets. Currently available data cannot definitively establish the ortho-para ratios in the atmospheres of Uranus and Neptune, but suggest values closer to local equilibrium than to the 3.1 normal ratio. Modeling of sub-millimeter wavelength measurements of these planets suggest thermal structures with frozen equilibrium lapse rates in their convective regions.

  2. Para hydrogen equilibration in the atmospheres of the outer planets

    NASA Astrophysics Data System (ADS)

    Conrath, Barney J.

    1986-10-01

    The thermodynamic behavior of the atmospheres of the Jovian planets is strongly dependent on the extent to which local thermal equilibration of the ortho and para states of molecular hydrogen is achieved. Voyager IRIS data from Jupiter imply substantial departures of the para hydrogen fraction from equilibrium in the upper troposphere at low latitudes, but with values approaching equilibrium at higher latitudes. Data from Saturn are less sensitive to the orth-para ratio, but suggest para hydrogen fractions near the equilibrium value. Above approximately the 200 K temperature level, para hydrogen conversion can enhance the efficiency of convection, resulting in a substantial increase in overturning times on all of the outer planets. Currently available data cannot definitively establish the ortho-para ratios in the atmospheres of Uranus and Neptune, but suggest values closer to local equilibrium than to the 3.1 normal ratio. Modeling of sub-millimeter wavelength measurements of these planets suggest thermal structures with frozen equilibrium lapse rates in their convective regions.

  3. RAMAN SCATTERING BY MOLECULAR HYDROGEN AND NITROGEN IN EXOPLANETARY ATMOSPHERES

    SciTech Connect

    Oklopčić, Antonija; Hirata, Christopher M.; Heng, Kevin, E-mail: oklopcic@astro.caltech.edu

    2016-11-20

    An important source of opacity in exoplanet atmospheres at short visible and near-UV wavelengths is Rayleigh scattering of light on molecules. It is accompanied by a related, albeit weaker process—Raman scattering. We analyze the signatures of Raman scattering imprinted in the reflected light and the geometric albedo of exoplanets, which could provide information about atmospheric properties. Raman scattering affects the geometric albedo spectra of planets in the following ways. First, it causes filling-in of strong absorption lines in the incident radiation, thus producing sharp peaks in the albedo. Second, it shifts the wavelengths of spectral features in the reflected lightmore » causing the so-called Raman ghost lines. Raman scattering can also cause a broadband reduction of the albedo due to wavelength shifting of a stellar spectrum with red spectral index. Observing the Raman peaks in the albedo could be used to measure the column density of gas, thus providing constraints on the presence of clouds in the atmosphere. Observing the Raman ghost lines could be used to spectroscopically identify the main scatterer in the atmosphere, even molecules like H{sub 2} or N{sub 2}, which do not have prominent spectral signatures in the optical wavelength range. If detected, ghost lines could also provide information about the temperature of the atmosphere. In this paper, we investigate the effects of Raman scattering in hydrogen- and nitrogen-dominated atmospheres. We analyze the feasibility of detecting the signatures of Raman scattering with the existing and future observational facilities, and of using these signatures as probes of exoplanetary atmospheres.« less

  4. McPHAC: McGill Planar Hydrogen Atmosphere Code

    NASA Astrophysics Data System (ADS)

    Haakonsen, Christian Bernt; Turner, Monica L.; Tacik, Nick A.; Rutledge, Robert E.

    2012-10-01

    The McGill Planar Hydrogen Atmosphere Code (McPHAC) v1.1 calculates the hydrostatic equilibrium structure and emergent spectrum of an unmagnetized hydrogen atmosphere in the plane-parallel approximation at surface gravities appropriate for neutron stars. McPHAC incorporates several improvements over previous codes for which tabulated model spectra are available: (1) Thomson scattering is treated anisotropically, which is shown to result in a 0.2%-3% correction in the emergent spectral flux across the 0.1-5 keV passband; (2) the McPHAC source code is made available to the community, allowing it to be scrutinized and modified by other researchers wishing to study or extend its capabilities; and (3) the numerical uncertainty resulting from the discrete and iterative solution is studied as a function of photon energy, indicating that McPHAC is capable of producing spectra with numerical uncertainties <0.01%. The accuracy of the spectra may at present be limited to ~1%, but McPHAC enables researchers to study the impact of uncertain inputs and additional physical effects, thereby supporting future efforts to reduce those inaccuracies. Comparison of McPHAC results with spectra from one of the previous model atmosphere codes (NSA) shows agreement to lsim1% near the peaks of the emergent spectra. However, in the Wien tail a significant deficit of flux in the spectra of the previous model is revealed, determined to be due to the previous work not considering large enough optical depths at the highest photon frequencies. The deficit is most significant for spectra with T eff < 105.6 K, though even there it may not be of much practical importance for most observations.

  5. Simple atmospheric hydrogen/deuterium exchange method for enumeration of labile hydrogens by electrospray ionization mass spectrometry.

    PubMed

    Kostyukevich, Yury; Kononikhin, Alexey; Popov, Igor; Nikolaev, Eugene

    2013-06-04

    A simple method for hydrogen/deuterium exchange in a standard electrospray (ESI) ionization source is presented. In this method, a D₂O droplet is placed between the ESI needle and the entrance of the mass spectrometer and thus saturation of the atmosphere with deuterated vapor in the ESI region is achieved. It was shown that full exchange of up to 23 labile acidic hydrogens with a minimal back exchange with the surrounding atmospheric water can be performed by this method.

  6. SEISMOLOGY OF A MASSIVE PULSATING HYDROGEN ATMOSPHERE WHITE DWARF

    SciTech Connect

    Kepler, S. O.; Pelisoli, Ingrid; Pecanha, Viviane

    2012-10-01

    We report our observations of the new pulsating hydrogen atmosphere white dwarf SDSS J132350.28+010304.22. We discovered periodic photometric variations in frequency and amplitude that are commensurate with nonradial g-mode pulsations in ZZ Ceti stars. This, along with estimates for the star's temperature and gravity, establishes it as a massive ZZ Ceti star. We used time-series photometric observations with the 4.1 m SOAR Telescope, complemented by contemporary McDonald Observatory 2.1 m data, to discover the photometric variability. The light curve of SDSS J132350.28+010304.22 shows at least nine detectable frequencies. We used these frequencies to make an asteroseismic determination of the totalmore » mass and effective temperature of the star: M{sub *} = 0.88 {+-} 0.02 M{sub Sun} and T{sub eff} = 12, 100 {+-} 140 K. These values are consistent with those derived from the optical spectra and photometric colors.« less

  7. Detection of hydrogen sulfide above the clouds in Uranus's atmosphere

    NASA Astrophysics Data System (ADS)

    Irwin, Patrick G. J.; Toledo, Daniel; Garland, Ryan; Teanby, Nicholas A.; Fletcher, Leigh N.; Orton, Glenn A.; Bézard, Bruno

    2018-04-01

    Visible-to-near-infrared observations indicate that the cloud top of the main cloud deck on Uranus lies at a pressure level of between 1.2 bar and 3 bar. However, its composition has never been unambiguously identified, although it is widely assumed to be composed primarily of either ammonia or hydrogen sulfide (H2S) ice. Here, we present evidence of a clear detection of gaseous H2S above this cloud deck in the wavelength region 1.57-1.59 μm with a mole fraction of 0.4-0.8 ppm at the cloud top. Its detection constrains the deep bulk sulfur/nitrogen abundance to exceed unity (>4.4-5.0 times the solar value) in Uranus's bulk atmosphere, and places a lower limit on the mole fraction of H2S below the observed cloud of (1.0 -2.5 ) ×1 0-5. The detection of gaseous H2S at these pressure levels adds to the weight of evidence that the principal constituent of 1.2-3-bar cloud is likely to be H2S ice.

  8. Hydrogen-water vapor mixtures: Control of hydrothermal atmospheres by hydrogen osmosis

    USGS Publications Warehouse

    Shaw, H.R.

    1963-01-01

    Experiments at 700??C and 800 bars total pressure demonstrate positive deviations from ideality for mixtures of hydrogen and H2O gases. The deviations are greater than predicted with Stockmayer's method. The composition of the mixture and the fugacity of hydrogen are controlled by diffusing hydrogen through metallic membranes. The results give the fugacities of both H 2O and oxygen.

  9. Ignition during hydrogen release from high pressure into the atmosphere

    NASA Astrophysics Data System (ADS)

    Oleszczak, P.; Wolanski, P.

    2010-12-01

    The first investigations concerned with a problem of hydrogen jet ignition, during outflow from a high-pressure vessel were carried out nearly 40 years ago by Wolanski and Wojcicki. The research resulted from a dramatic accident in the Chorzow Chemical Plant Azoty, where the explosion of a synthesis gas made up of a mixture composed of three moles of hydrogen per mole of nitrogen, at 300°C and 30 MPa killed four people. Initial investigation had excluded potential external ignition sources and the main aim of the research was to determine the cause of ignition. Hydrogen is currently considered as a potential fuel for various vehicles such as cars, trucks, buses, etc. Crucial safety issues are of potential concern, associated with the storage of hydrogen at a very high pressure. Indeed, the evidence obtained nearly 40 years ago shows that sudden rupture of a high-pressure hydrogen storage tank or other component can result in ignition and potentially explosion. The aim of the present research is identification of the conditions under which hydrogen ignition occurs as a result of compression and heating of the air by the shock wave generated by discharge of high-pressure hydrogen. Experiments have been conducted using a facility constructed in the Combustion Laboratory of the Institute of Heat Engineering, Warsaw University of Technology. Tests under various configurations have been performed to determine critical conditions for occurrence of high-pressure hydrogen ignition. The results show that a critical pressure exists, leading to ignition, which depends mainly on the geometric configuration of the outflow system, such as tube diameter, and on the presence of obstacles.

  10. The Stability of Hydrogen-Rich Atmospheres of Earth-Like Planets

    NASA Technical Reports Server (NTRS)

    Zahnle, Kevin

    2016-01-01

    Understanding hydrogen escape is essential to understanding the limits to habitability, both for liquid water where the Sun is bright, but also to assess the true potential of H2 as a greenhouse gas where the Sun is faint. Hydrogen-rich primary atmospheres of Earth-like planets can result either from gravitational capture of solar nebular gases (with helium), or from impact shock processing of a wide variety of volatile-rich planetesimals (typically accompanied by H2O, CO2, and under the right circumstances, CH4). Most studies of hydrogen escape from planets focus on determining how fast the hydrogen escapes. In general this requires solving hydro- dynamic equations that take into account the acceleration of hydrogen through a critical transonic point and an energy budget that should include radiative heating and cooling, thermal conduction, the work done in lifting the hydrogen against gravity, and the residual heat carried by the hydrogen as it leaves. But for planets from which hydrogen escape is modest or insignificant, the atmosphere can be approximated as hydrostatic, which is much simpler, and for which a relatively full-featured treatment of radiative cooling by embedded molecules, atoms, and ions such as CO2 and H3+ is straightforward. Previous work has overlooked the fact that the H2 molecule is extremely efficient at exciting non-LTE CO2 15 micron emission, and thus that radiative cooling can be markedly more efficient when H2 is abundant. We map out the region of phase space in which terrestrial planets keep hydrogen-rich atmospheres, which is what we actually want to know for habitability. We will use this framework to reassess Tian et al's hypothesis that H2-rich atmospheres may have been rather long-lived on Earth itself. Finally, we will address the empirical observation that rocky planets with thin or negligible atmospheres are rarely or never bigger than 1.6 Earth radii.

  11. Hydrogen and deuterium loss from the terrestrial atmosphere - A quantitative assessment of nonthermal escape fluxes

    NASA Technical Reports Server (NTRS)

    Yung, Yuk L.; Wen, Jun-Shan; Moses, Julianne I.; Landry, Bridget M.; Allen, Mark; Hsu, Kuang-Jung

    1989-01-01

    A comprehensive one-dimensional photochemical model extending from the middle atmosphere (50 km) to the exobase (432 km) has been used to study the escape of hydrogen and deuterium from the earth's atmosphere. The model incorporates recent advances in chemical kinetics as well as atmospheric observations by satellites, especially the Atmosphere Explorer C satellite. The results suggest that the escape fluxes of both H and D are limited by the upward transport of total hydrogen and total deuterium at the homopause. About one fourth of total hydrogen escape is thermal, the rest being nonthermal. It is shown that escape of D is nonthermal and that charge exchange and polar wind are important mechanisms for the nonthermal escape of H and D.

  12. How atmospheric CO2 concentrations can affect the hydrogen isotope composition of plant organic compounds

    NASA Astrophysics Data System (ADS)

    Cormier, M. A.; Werner, R. A.; Kahmen, A.

    2016-12-01

    In contrast to the stable carbon, nitrogen and oxygen isotope composition of plant materials, the hydrogen isotope composition of plant organic compounds has not yet been established as a tool in ecological or biogeochemical research. With the development of new analytical instruments that allow the hydrogen isotope analysis of selected plant compounds there is, however, a growing interest to explore the power of hydrogen isotopes as tools for ecological and biogeochemical research. In my presentation, I will summarize recent works from greenhouse experiments showing how, mechanistically, the CO2 concentrations in the atmosphere can affect the hydrogen isotope composition of lipids and cellulose via the carbon and energy metabolism in plants: Our experiments revealed that plants growing under lower atmospheric CO2 concentrations (i.e. 140 ppm) are generally 2H enriched compared to plants growing in contemporary and even higher atmospheric CO2 concentrations (i.e. 400 and 800 ppm). We were able to identify various biochemical processes during the biosynthesis of plant tissue that contribute to these patterns and hope that this will help to establish hydrogen isotope composition of plant derived compounds as a robust proxy for the carbon and energy metabolism in plants that could serve as an important new tool in plant ecology, biogeochemistry and paleoclimatology. This new insight in the biosynthetic fractionation of hydrogen isotopes in plants might also explain a large amount of the scatter observed when looking at the relation between the precipitation and the leaf wax n-alkanes hydrogen isotope composition. This might be particularly relevant for paleo-hydrological studies using hydrogen isotopes in geological transitions where the atmospheric CO2 concentrations vary significantly such as during the glacial-interglacial transitions.

  13. Atmospheric chemistry of hydrogen halides: Reactions on ice and in strong acids

    SciTech Connect

    Ravishankara, A.R.

    1995-12-31

    Reactions of hydrogen halides, HCl, HBr, and HI, in sulfuric acid droplets, ice, and liquid water play important roles in the chemistry of Earth`s atmosphere. The hydrogen halides react with other species such as HOCl, ClONO{sub 2}, BrONO{sub 2}, and HOBr to liberate active halogens, the form that can destroy ozone. The impact of these reactions on the chemistry of the ozone in the atmosphere will be described. Also, a brief discussion of the mechanisms of these reactions will be given. Possible experimental and theoretical investigations that can shed light on these reactions will be pointed out.

  14. Outer satellite atmospheres: Their extended nature and planetary interactions. [sodium cloud of Io, hydrogen torus of Titan, and comet atmospheres

    NASA Technical Reports Server (NTRS)

    Smyth, W. H.

    1980-01-01

    Highly developed numerical models are applied to interpret extended-atmosphere data for the sodium cloud of Io and the hydrogen torus of Titan. Solar radiation pressure was identified and verified by model calculations as the mechanism to explain two different east-west asymmetries observed in the sodium cloud. Analysis of sodium line profile data, suggesting that a Jupiter magnetospheric wind may be responsible for high speed sodium atoms emitted from Io, and preliminary modeling of the interaction of the Io plasma torus and Io's sodium cloud are also reported. Models presented for Titan's hydrogen torus are consistent both with the recent Pioneer 11 measurements and earlier Earth-orbiting observations by the Copernicus satellite. Progress is reported on developing models for extended gas and dust atmospheres of comets.

  15. On the Spectral Evolution of Helium-atmosphere White Dwarfs Showing Traces of Hydrogen

    NASA Astrophysics Data System (ADS)

    Rolland, B.; Bergeron, P.; Fontaine, G.

    2018-04-01

    We present a detailed spectroscopic analysis of 115 helium-line (DB) and 28 cool, He-rich hydrogen-line (DA) white dwarfs based on atmosphere fits to optical spectroscopy and photometry. We find that 63% of our DB population show hydrogen lines, making them DBA stars. We also demonstrate the persistence of pure DB white dwarfs with no detectable hydrogen feature at low effective temperatures. Using state-of-the art envelope models, we next compute the total quantity of hydrogen, M H, that is contained in the outer convection zone as a function of effective temperature and atmospheric H/He ratio. We find that some (T eff, M H) pairs cannot physically exist as a homogeneously mixed structure; such a combination can only occur as stratified objects of the DA spectral type. On that basis, we show that the values of M H inferred for the bulk of the DBA stars are too large and incompatible with the convective dilution scenario. We also present evidence that the hydrogen abundances measured in DBA and cool, helium-rich white dwarfs cannot be globally accounted for by any kind of accretion mechanism onto a pure DB star. We suggest that cool, He-rich DA white dwarfs are most likely created by the convective mixing of a DA star with a thin hydrogen envelope; they are not cooled down DBAs. We finally explore several scenarios that could account for the presence of hydrogen in DBA stars.

  16. Hydrogen-nitrogen greenhouse warming in Earth's early atmosphere.

    PubMed

    Wordsworth, Robin; Pierrehumbert, Raymond

    2013-01-04

    Understanding how Earth has sustained surface liquid water throughout its history remains a key challenge, given that the Sun's luminosity was much lower in the past. Here we show that with an atmospheric composition consistent with the most recent constraints, the early Earth would have been significantly warmed by H(2)-N(2) collision-induced absorption. With two to three times the present-day atmospheric mass of N(2) and a H(2) mixing ratio of 0.1, H(2)-N(2) warming would be sufficient to raise global mean surface temperatures above 0°C under 75% of present-day solar flux, with CO(2) levels only 2 to 25 times the present-day values. Depending on their time of emergence and diversification, early methanogens may have caused global cooling via the conversion of H(2) and CO(2) to CH(4), with potentially observable consequences in the geological record.

  17. Hydrogen.

    PubMed

    Bockris, John O'M

    2011-11-30

    The idea of a "Hydrogen Economy" is that carbon containing fuels should be replaced by hydrogen, thus eliminating air pollution and growth of CO₂ in the atmosphere. However, storage of a gas, its transport and reconversion to electricity doubles the cost of H₂ from the electrolyzer. Methanol made with CO₂ from the atmosphere is a zero carbon fuel created from inexhaustible components from the atmosphere. Extensive work on the splitting of water by bacteria shows that if wastes are used as the origin of feed for certain bacteria, the cost for hydrogen becomes lower than any yet known. The first creation of hydrogen and electricity from light was carried out in 1976 by Ohashi et al. at Flinders University in Australia. Improvements in knowledge of the structure of the semiconductor-solution system used in a solar breakdown of water has led to the discovery of surface states which take part in giving rise to hydrogen (Khan). Photoelectrocatalysis made a ten times increase in the efficiency of the photo production of hydrogen from water. The use of two electrode cells; p and n semiconductors respectively, was first introduced by Uosaki in 1978. Most photoanodes decompose during the photoelectrolysis. To avoid this, it has been necessary to create a transparent shield between the semiconductor and its electronic properties and the solution. In this way, 8.5% at 25 °C and 9.5% at 50 °C has been reached in the photo dissociation of water (GaP and InAs) by Kainthla and Barbara Zeleney in 1989. A large consortium has been funded by the US government at the California Institute of Technology under the direction of Nathan Lewis. The decomposition of water by light is the main aim of this group. Whether light will be the origin of the post fossil fuel supply of energy may be questionable, but the maximum program in this direction is likely to come from Cal. Tech.

  18. Hydrogen chemistry - Perspective on experiment and theory. [atmospheric chemistry

    NASA Technical Reports Server (NTRS)

    Kaufman, F.

    1975-01-01

    A review is presented of the advantages and limitations of various experimental methods for the investigation of the kinetics of hydrogen chemistry, including classic thermal and photochemical methods and the crossed molecular beam method. Special attention is given to the flash photolysis-resonance fluorescence apparatus developed by Braun et al, in which repetitive vacuum UV flashes result in the photolytic generation of the desired species, and to the discharge-flow technique. The use of various theoretical methods for the selection or elimination of kinetic data is considered in a brief discussion of the rate theory of two-body encounters and recombination-dissociation processes in neutral reactions. Recent kinetic studies of a series of OH reactions and of a major loss process for odd H in the stratosphere are summarized.

  19. Opacity of tungsten-seeded hydrogen to 2500 K and 115 atmospheres.

    NASA Technical Reports Server (NTRS)

    Williams, J. R.; Partain, W. L.; Clement, J. P.

    1971-01-01

    Experimental investigation and measurement of the radiant heat attenuation of an aerosol which may serve as a gas core nuclear-rocket propellant. The experiment uses a tungsten-hydrogen aerosol heated to temperatures as high as 2500 K under pressures up to 115 atmospheres. The hydrogen aerosol is produced by dispersion of submicron-sized particles of tungsten in hydrogen gas. A narrow beam of broad spectrum (visible and ultraviolet) light is passed through it with the attenuation being measured as a function of wavelength. Other aerosol characteristics examined include the nature and extent of chemical reactions between the seed material and the hydrogen and the degree of dispersion of the seed material obtained before and after heating. Chemical equilibrium calculations and vapor pressure data for the refractory metals indicate that tungsten is a prime candidate for the seed material in the gas core nuclear rocket.

  20. Middle atmosphere heating by exothermic chemical reactions involving odd-hydrogen species

    NASA Technical Reports Server (NTRS)

    Mlynczak, Martin G.; Solomon, Susan

    1991-01-01

    The rate of heating which occurs in the middle atmosphere due to four exothermic reactions involving members of the odd-hydrogen family is calculated. The following reactions are considered: O + OH yields O2 + H; H + O2 + M yields HO2 + M; H + O3 yields OH + O2; and O + HO2 yields OH + O2. It is shown that the heating rates due to these reactions rival the oxygen-related heating rates conventionally considered in middle-atmosphere models. The conversion of chemical potential energy into molecular translational energy (heat) by these odd-hydrogen reactions is shown to be a significant energy source in the middle atmosphere that has not been previously considered.

  1. Effects of atmospheric hydrogen sulfide concentration on growth and meat quality in broiler chickens.

    PubMed

    Wang, Y; Huang, M; Meng, Q; Wang, Y

    2011-11-01

    A total of 384 commercial Arbor Acres broilers (one-half males and one-half females; 1 d of age) were randomly allotted to 4 treatments to study the effects of atmospheric hydrogen sulfide on growth performance, blood parameters, and meat quality. Each treatment was placed in a separate environmentally controlled chamber. Group A was the control group; no hydrogen sulfide was added to chamber A to maintain near 0 mg/kg of hydrogen sulfide from wk 0 to 6. Groups B, C, and D were trial groups that were subjected to 2, 4, and 8 mg/kg of hydrogen sulfide, respectively, from wk 0 to 3 and to 3, 6, and 12 mg/kg of hydrogen sulfide, respectively, from wk 4 to 6. The results showed that the average daily intake and BW decreased whereas feed:gain and concentration of hydrogen sulfide increased from wk 0 to 3. The number of white blood cells, red blood cells, and hematocrit increased slightly with increasing exposure to hydrogen sulfide, but no significant difference was found. The highly concentrated hydrogen sulfide (12 mg/kg) significantly decreased the yield of carcass and pH of leg and increased water loss rate of breast and leg. Therefore, the results suggest that hydrogen sulfide had a negative effect on the performance of broilers and that the suitable hydrogen sulfide concentration should be less than 2 mg/kg from 0 to 3 wk of age and less than 6 mg/kg from 3 to 6 wk of age for broiler production and health.

  2. The Evolution of Deuterium and Hydrogen in the Martian Upper Atmosphere

    NASA Astrophysics Data System (ADS)

    Clarke, J. T.; Mayyasi, M.; Bhattacharyya, D.; Chaufray, J. Y.; Bertaux, J. L.; Villanueva, G. L.; Halekas, J. S.; Chaffin, M.; Deighan, J.; Schneider, N.; Jain, S.; Jakosky, B. M.

    2017-12-01

    Understanding the ratio of deuterium to hydrogen (D/H) in the atmosphere of Mars is key to understanding the history of water and its escape into space. Observations of HDO and H2O near the surface have shown factor of two-three differences depending on the hemisphere and season. By contrast, observations by multiple spacecraft have now shown order of magnitude changes in the densities and escape fluxes of both H and D with an annual cycle in the upper atmosphere of Mars. The maxima occur shortly after perihelion, during southern summer, and are associated with increased levels of water in the middle atmosphere as well as increased solar UV flux at Mars. Work remains to sort out the relative influence of solar EUV flux in the upper atmosphere and transport of H and D from the lower atmosphere, which can be affected by global circulation and dust storms.

  3. Bonded and Sealed External Insulations for Liquid-Hydrogen-Fueled Rocket Tanks During Atmospheric Flight

    NASA Technical Reports Server (NTRS)

    Gray, V. H.; Gelder, T. F.; Cochran, R. P.; Goodykoontz, J. H.

    1960-01-01

    Several currently available nonmetallic insulation materials that may be bonded onto liquid-hydrogen tanks and sealed against air penetration into the insulation have been investigated for application to rockets and spacecraft. Experimental data were obtained on the thermal conductivities of various materials in the cryogenic temperature range, as well as on the structural integrity and ablation characteristics of these materials at high temperatures occasioned by aerodynamic heating during atmospheric escape. Of the materials tested, commercial corkboard has the best overall properties for the specific requirements imposed during atmospheric flight of a high-acceleration rocket vehicle.

  4. Hydrogen

    PubMed Central

    Bockris, John O’M.

    2011-01-01

    The idea of a “Hydrogen Economy” is that carbon containing fuels should be replaced by hydrogen, thus eliminating air pollution and growth of CO2 in the atmosphere. However, storage of a gas, its transport and reconversion to electricity doubles the cost of H2 from the electrolyzer. Methanol made with CO2 from the atmosphere is a zero carbon fuel created from inexhaustible components from the atmosphere. Extensive work on the splitting of water by bacteria shows that if wastes are used as the origin of feed for certain bacteria, the cost for hydrogen becomes lower than any yet known. The first creation of hydrogen and electricity from light was carried out in 1976 by Ohashi et al. at Flinders University in Australia. Improvements in knowledge of the structure of the semiconductor-solution system used in a solar breakdown of water has led to the discovery of surface states which take part in giving rise to hydrogen (Khan). Photoelectrocatalysis made a ten times increase in the efficiency of the photo production of hydrogen from water. The use of two electrode cells; p and n semiconductors respectively, was first introduced by Uosaki in 1978. Most photoanodes decompose during the photoelectrolysis. To avoid this, it has been necessary to create a transparent shield between the semiconductor and its electronic properties and the solution. In this way, 8.5% at 25 °C and 9.5% at 50 °C has been reached in the photo dissociation of water (GaP and InAs) by Kainthla and Barbara Zeleney in 1989. A large consortium has been funded by the US government at the California Institute of Technology under the direction of Nathan Lewis. The decomposition of water by light is the main aim of this group. Whether light will be the origin of the post fossil fuel supply of energy may be questionable, but the maximum program in this direction is likely to come from Cal. Tech. PMID:28824125

  5. Seasonal variability of soil sink for atmospheric hydrogen: a case study from southern Poland

    NASA Astrophysics Data System (ADS)

    Bartyzel, J.; Pycia, M.; Necki, J. M.; Rozanski, K.

    2009-04-01

    Although hydrogen is rarely mentioned as a greenhouse gas, it is expected that elevated concentrations of this gas in the atmosphere in the coming decades, associated with massive anthropogenic emissions may lead to longer residence time of atmospheric CH4 and associated enhancement of the greenhouse effect. The global average mixing ratio of atmospheric H2 amounts at present to approximately 500 ppb. The sources and sinks of hydrogen are not well quantified. In particular, little is known about the strength and spatial and temporal variability of hydrogen uptake by soils. The EU 6th Framework Project EUROHYDROS is aimed at initialising European monitoring capability for atmospheric hydrogen, including the ability to derive isotope ratios and to use these observations, together with studies on sinks and sources of H2 and modelling work, to improve the understanding of hydrogen budget on the global scale. As a part of EUROHYDROS project, a dedicated study aimed at quantifying seasonal variability of soil sink for atmospheric hydrogen is being conducted in southern Poland. The experimental site is located on the outskirts of Krakow, a large city with numerous anthropogenic sources of H2. To quantify the soil sink for H2, a dedicated equipment has been constructed, based on the inverted cap principle. To quantify the uptake of H2 by soils, a 20-liter chamber made of stainless steel and plexiglas is placed on the soil surface and concentration of hydrogen inside the chamber is measured in regular time intervals in order to quantify the dynamics H2 removal via enzymatic reactions taking place in the upper soil layers. The concentration of hydrogen was measured in samples of air collected under the chamber in specified time intervals. A commercially available instrument (Peak Performer 1, Peak Laboratories, USA) equipped with RGA detector was used for this purpose. The measurements were performed regularly every two weeks. Apart of hydrogen concentrations, also several

  6. Inhalation toxicology. IV., Times to incapacitation and death for rats exposed continuously to atmospheric hydrogen chloride gas.

    DOT National Transportation Integrated Search

    1985-05-01

    Laboratory rats were exposed continuously to measured atmospheric concentrations of hydrogen chloride (HC1) gas until they expired. The exposure time required to produce lethality was measured, as was the time at which physical incapacitation occurre...

  7. In situ TEM studies of the shape evolution of Pd nanocrystals under oxygen and hydrogen environments at atmospheric pressure.

    PubMed

    Zhang, Xun; Meng, Jun; Zhu, Beien; Yu, Jian; Zou, Shihui; Zhang, Ze; Gao, Yi; Wang, Yong

    2017-12-12

    We demonstrate an atomic scale TEM observation of shape evolutions of Pd nanocrystals under oxygen and hydrogen environments at atmospheric pressure. Combined with multi-scale structure reconstruction model calculations, the reshaping mechanism is fully understood.

  8. Trace hydrogen in helium atmosphere white dwarfs as a possible signature of water accretion

    NASA Astrophysics Data System (ADS)

    Gentile Fusillo, Nicola Pietro; Gänsicke, Boris T.; Farihi, Jay; Koester, Detlev; Schreiber, Matthias R.; Pala, Anna F.

    2017-06-01

    A handful of white dwarfs with helium-dominated atmospheres contain exceptionally large masses of hydrogen in their convection zones, with the metal-polluted white dwarf GD 16 being one of the earliest recognized examples. We report the discovery of a similar star: the white dwarf coincidentally named GD 17. We obtained medium-resolution spectroscopy of both GD 16 and GD 17 and calculated abundances and accretion rates of photospheric H, Mg, Ca, Ti, Fe and Ni. The metal abundance ratios indicate that the two stars recently accreted debris, which is Mg-poor compared to the composition of bulk Earth. However, unlike the metal pollutants, H never diffuses out of the atmosphere of white dwarfs and we propose that the exceptionally high atmospheric H content of GD 16 and GD 17 (2.2 × 1024 and 2.9 × 1024 g, respectively) could result from previous accretion of water bearing planetesimals. Comparing the detection of trace H and metal pollution among 729 helium atmosphere white dwarfs, we find that the presence of H is nearly twice as common in metal-polluted white dwarfs compared to their metal-free counterparts. This highly significant correlation indicates that, over the cooling age of the white dwarfs, at least some fraction of the H detected in many He atmospheres (including GD 16 and GD 17) is accreted alongside metal pollutants, where the most plausible source is water. In this scenario, water must be common in systems with rocky planetesimals.

  9. Atomic-scale investigation of point defects and hydrogen-solute atmospheres on the edge dislocation mobility in alpha iron

    SciTech Connect

    Bhatia, M. A.; Solanki, K. N., E-mail: kiran.solanki@asu.edu; Groh, S.

    2014-08-14

    In this study, we present atomistic mechanisms of 1/2 [111](11{sup ¯}0) edge dislocation interactions with point defects (hydrogen and vacancies) and hydrogen solute atmospheres in body centered cubic (bcc) iron. In metals such as iron, increases in hydrogen concentration can increase dislocation mobility and/or cleavage-type decohesion. Here, we first investigate the dislocation mobility in the presence of various point defects, i.e., change in the frictional stress as the edge dislocation interacts with (a) vacancy, (b) substitutional hydrogen, (c) one substitutional and one interstitial hydrogen, (d) interstitial hydrogen, (e) vacancy and interstitial hydrogen, and (f) two interstitial hydrogen. Second, we examinemore » the role of a hydrogen-solute atmosphere on the rate of local dislocation velocity. The edge dislocation simulation with a vacancy in the compression side of the dislocation and an interstitial hydrogen atom at the tension side exhibit the strongest mechanical response, suggesting a higher potential barrier and hence, the higher frictional stress (i.e., ∼83% higher than the pure iron Peierls stress). In the case of a dislocation interacting with a vacancy on the compressive side, the vacancy binds with the edge dislocation, resulting in an increase in the friction stress of about 28% when compared with the Peierls stress of an edge dislocation in pure iron. Furthermore, as the applied strain increases, the vacancy migrates through a dislocation transportation mechanism by attaining a velocity of the same order as the dislocation velocity. For the case of the edge dislocation interacting with interstitial hydrogen on the tension side, the hydrogen atom jumps through one layer perpendicular to the glide plane during the pinning-unpinning process. Finally, our simulation of dislocation interactions with hydrogen show first an increase in the local dislocation velocity followed by a pinning of the dislocation core in the atmosphere, resulting in

  10. The effect of particle precipitation events on the neutral and ion chemistry of the middle atmosphere. II - Odd hydrogen

    NASA Technical Reports Server (NTRS)

    Solomon, S.; Rusch, D. W.; Gerard, J.-C.; Reid, G. C.; Crutzen, P. J.

    1981-01-01

    A one dimensional time-dependent model of the neutral and ion chemistry of the middle atmosphere has been used to examine the production of odd hydrogen (H, OH, and HO2) during charged particle precipitation. At altitudes above about 65 km, odd hydrogen production depends on the ionization rate, and the atomic oxygen and water vapor densities. Odd hydrogen production is shown to exhibit diurnal and other time dependent variations during such an event at these altitudes, and the assumption that two odd hydrogen particles are always produced per ionization is reexamined.

  11. Evaluation of passive card monitors for hydrogen sulfide for use in kraft pulp mill workplace atmospheres.

    PubMed

    Saunders, Fran; Larson, Leon; Tatum, Vickie

    2002-01-01

    Six different brands of passive card monitors representing three different types of card monitor were evaluated for their effectiveness in testing for hydrogen sulfide in workplace atmospheres. The cards were evaluated both in the laboratory and in a kraft pulp mill according to a protocol that closely follows that recommended by the National Institute for Occupational Safety and Health and other researchers for passive samplers. The performances of the Envirometrics Air-Chem Technologies and the Gilian ChemAir quantitative cards, the Gilian ChromAir and VICI Metronics Colortec semiquantitative cards, and the American Gas & Chemical Co. Leak-Tec and Gilian SafeAir indicator cards were evaluated. The detection limits of the cards were determined, and the cards were exposed to a range of hydrogen sulfide concentrations (1, 5, 10, 20 ppm), face velocities (0, 50 ft/min), and temperature/humidity combinations (95 degrees F/90% humidity, 77 degrees F/50% humidity, 40 degrees F/20% humidity). The cards' responses to short-term and variable concentration exposures as well as to the potential interferents methyl mercaptan, dimethyl sulfide, dimethyl disulfide, sulfur dioxide, and carbon monoxide were assessed. Each of the cards tested demonstrated a usefulness for the detection and/or quantification of hydrogen sulfide at concentrations and under conditions relevant to kraft pulp mill workplace atmospheres. Which card is best depends on the application, sampling conditions, and level of confidence necessary in the results. The Gilian ChemAir quantitative card performed well under most conditions with acceptable accuracy (13% lab, 26% field), and no response to potential interferents or to changes in face velocity, temperature, and humidity. The Envirometrics ACT quantitative cards did not perform as well, with an accuracy level of only 46% in the lab. They also seemed to be more affected by changes in face velocity, temperature, and humidity. Both semiquantitative cards

  12. Novel Diamond Films Synthesis Strategy: Methanol and Argon Atmosphere by Microwave Plasma CVD Method Without Hydrogen.

    PubMed

    Yang, Li; Jiang, Caiyi; Guo, Shenghui; Zhang, Libo; Gao, Jiyun; Peng, Jinhui; Hu, Tu; Wang, Liang

    2016-12-01

    Diamond thin films are grown on silicon substrates by only using methanol and argon mixtures in microwave plasma chemical vapor deposition (MPCVD) reactor. It is worth mentioning that the novel strategy makes the synthesis reaction works smoothly without hydrogen atmosphere, and the substrates temperature is only 500 °C. The evidence of surface morphology and thickness under different time is obtained by characterizing the samples using scanning electron microscopy (SEM). X-ray diffractometer (XRD) spectrum reveals that the preferential orientation of (111) plane sample is obtained. The Raman spectra indicate that the dominant component of all the samples is a diamond. Moreover, the diamond phase content of the targeted films was quantitatively analyzed by X-ray photoelectron spectroscopy (XPS) method, and the surface roughness of diamond films was investigated by atomic force microscope (AFM). Meanwhile, the possible synthesis mechanism of the diamond films in methanol- and argon-mixed atmosphere was discussed.

  13. Diphosphine is an intermediate in the photolysis of phosphine to phosphorus and hydrogen. [Jupiter atmospheric chemistry

    NASA Technical Reports Server (NTRS)

    Ferris, J. P.; Benson, R.

    1980-01-01

    The photolysis of phosphine to red phosphorus (P4) and hydrogen is investigated in light of the potential significance of the reaction in the atmospheric chemistry of Jupiter. It is reported that the photolysis of PH3 at room temperature by a 206.2-nm light source gave rise to a product identified by its UV and IR spectra and gas chromatographic retention time as P2H4, the yield of which is found to increase to a maximum and then decrease to 20% of the maximum value with illumination time. A mechanism for phosphine photolysis including diphosphine formation as an intermediate step is proposed, and it is concluded that P2H4 is a likely constituent of the atmospheres of the Jovian planets.

  14. Surface preparation for high purity alumina ceramics enabling direct brazing in hydrogen atmospheres

    DOEpatents

    Cadden, Charles H.; Yang, Nancy Yuan Chi; Hosking, Floyd M.

    2001-01-01

    The present invention relates to a method for preparing the surface of a high purity alumina ceramic or sapphire specimen that enables direct brazing in a hydrogen atmosphere using an active braze alloy. The present invention also relates to a method for directly brazing a high purity alumina ceramic or sapphire specimen to a ceramic or metal member using this method of surface preparation, and to articles produced by this brazing method. The presence of silicon, in the form of a SiO.sub.2 -containing surface layer, can more than double the tensile bond strength in alumina ceramic joints brazed in a hydrogen atmosphere using an active Au-16Ni-0.75 Mo-1.75V filler metal. A thin silicon coating applied by PVD processing can, after air firing, produce a semi-continuous coverage of the alumina surface with a SiO.sub.2 film. Room temperature tensile strength was found to be proportional to the fraction of air fired surface covered by silicon-containing films. Similarly, the ratio of substrate fracture versus interface separation was also related to the amount of surface silicon present prior to brazing. This process can replace the need to perform a "moly-manganese" metallization step.

  15. Exoplanet HD 209458b: Inflated Hydrogen Atmosphere but No Sign of Evaporation

    NASA Astrophysics Data System (ADS)

    Ben-Jaffel, Lotfi

    2007-12-01

    Many extrasolar planets orbit closely to their parent star. Their existence raises the fundamental problem of loss and gain in their mass. For exoplanet HD 209458b, reports on an unusually extended hydrogen corona and a hot layer in the lower atmosphere seem to support the scenario of atmospheric inflation by the strong stellar irradiation. However, difficulties in reconciling evaporation models with observations call for a reassessment of the problem. Here we use HST archive data to report a new absorption rate of ~8.9% +/- 2.1% by atomic hydrogen during the HD 209458b transit and show that no sign of evaporation could be detected for the exoplanet. We also report evidence of time variability in the HD 209458 Lyα flux, a variability that was not accounted for in previous studies, which corrupted their diagnostics. Mass-loss rates thus far proposed in the literature in the range 5×(1010-1011) g s-1 must induce a spectral signature in the Lyα line profile of HD 209458 that cannot be found in the present analysis. Either an unknown compensation effect is hiding the expected spectral feature or else the mass-loss rate of neutrals from HD 209458 is modest.

  16. THE McGill PLANAR HYDROGEN ATMOSPHERE CODE (McPHAC)

    SciTech Connect

    Haakonsen, Christian Bernt; Turner, Monica L.; Tacik, Nick A.

    2012-04-10

    The McGill Planar Hydrogen Atmosphere Code (McPHAC) v1.1 calculates the hydrostatic equilibrium structure and emergent spectrum of an unmagnetized hydrogen atmosphere in the plane-parallel approximation, at surface gravities appropriate for neutron stars. McPHAC incorporates several improvements over previous codes for which tabulated model spectra are available: (1) Thomson scattering is treated anisotropically, which is shown to result in a 0.2%-3% correction in the emergent spectral flux across the 0.1-5 keV passband; (2) the McPHAC source code is made available to the community, allowing it to be scrutinized and modified by other researchers wishing to study or extend its capabilities; andmore » (3) the numerical uncertainty resulting from the discrete and iterative solution is studied as a function of photon energy, indicating that McPHAC is capable of producing spectra with numerical uncertainties <0.01%. The accuracy of the spectra may at present be limited to {approx}1%, but McPHAC enables researchers to study the impact of uncertain inputs and additional physical effects, thereby supporting future efforts to reduce those inaccuracies. Comparison of McPHAC results with spectra from one of the previous model atmosphere codes (NSA) shows agreement to {approx}<1% near the peaks of the emergent spectra. However, in the Wien tail a significant deficit of flux in the spectra of the previous model is revealed, determined to be due to the previous work not considering large enough optical depths at the highest photon frequencies. The deficit is most significant for spectra with T{sub eff} < 10{sup 5.6} K, though even there it may not be of much practical importance for most observations.« less

  17. The McGill Planar Hydrogen Atmosphere Code (McPHAC)

    NASA Astrophysics Data System (ADS)

    Haakonsen, Christian Bernt; Turner, Monica L.; Tacik, Nick A.; Rutledge, Robert E.

    2012-04-01

    The McGill Planar Hydrogen Atmosphere Code (McPHAC) v1.1 calculates the hydrostatic equilibrium structure and emergent spectrum of an unmagnetized hydrogen atmosphere in the plane-parallel approximation, at surface gravities appropriate for neutron stars. McPHAC incorporates several improvements over previous codes for which tabulated model spectra are available: (1) Thomson scattering is treated anisotropically, which is shown to result in a 0.2%-3% correction in the emergent spectral flux across the 0.1-5 keV passband; (2) the McPHAC source code is made available to the community, allowing it to be scrutinized and modified by other researchers wishing to study or extend its capabilities; and (3) the numerical uncertainty resulting from the discrete and iterative solution is studied as a function of photon energy, indicating that McPHAC is capable of producing spectra with numerical uncertainties <0.01%. The accuracy of the spectra may at present be limited to ~1%, but McPHAC enables researchers to study the impact of uncertain inputs and additional physical effects, thereby supporting future efforts to reduce those inaccuracies. Comparison of McPHAC results with spectra from one of the previous model atmosphere codes (NSA) shows agreement to lsim1% near the peaks of the emergent spectra. However, in the Wien tail a significant deficit of flux in the spectra of the previous model is revealed, determined to be due to the previous work not considering large enough optical depths at the highest photon frequencies. The deficit is most significant for spectra with T eff < 105.6 K, though even there it may not be of much practical importance for most observations.

  18. Detection and isolation of plant-associated bacteria scavenging atmospheric molecular hydrogen.

    PubMed

    Kanno, Manabu; Constant, Philippe; Tamaki, Hideyuki; Kamagata, Yoichi

    2016-09-01

    High-affinity hydrogen (H2 )-oxidizing bacteria possessing group 5 [NiFe]-hydrogenase genes are important contributors to atmospheric H2 uptake in soil environments. Although previous studies reported the occurrence of a significant H2 uptake activity in vegetation, there has been no report on the identification and diversity of the responsible microorganisms. Here, we show the existence of plant-associated bacteria with the ability to consume atmospheric H2 that may be a potential energy source required for their persistence in plants. Detection of the gene hhyL - encoding the large subunit of group 5 [NiFe]-hydrogenase - in plant tissues showed that plant-associated high-affinity H2 -oxidizing bacteria are widely distributed in herbaceous plants. Among a collection of 145 endophytic isolates, seven Streptomyces strains were shown to possess hhyL gene and exhibit high- or intermediate-affinity H2 uptake activity. Inoculation of Arabidopsis thaliana (thale cress) and Oryza sativa (rice) seedlings with selected isolates resulted in an internalization of the bacteria in plant tissues. H2 uptake activity per bacterial cells was comparable between plant and soil, demonstrating that both environments are favourable for the H2 uptake activity of streptomycetes. This study first demonstrated the occurrence of plant-associated high-affinity H2 -oxidizing bacteria and proposed their potential contribution as atmospheric H2 sink. © 2015 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.

  19. Consumption of atmospheric hydrogen during the life cycle of soil-dwelling actinobacteria.

    PubMed

    Meredith, Laura K; Rao, Deepa; Bosak, Tanja; Klepac-Ceraj, Vanja; Tada, Kendall R; Hansel, Colleen M; Ono, Shuhei; Prinn, Ronald G

    2014-06-01

    Microbe-mediated soil uptake is the largest and most uncertain variable in the budget of atmospheric hydrogen (H2 ). The diversity and ecophysiological role of soil microorganisms that can consume low atmospheric abundances of H2 with high-affinity [NiFe]-hydrogenases is unknown. We expanded the library of atmospheric H2 -consuming strains to include four soil Harvard Forest Isolate (HFI) Streptomyces spp., Streptomyces cattleya and Rhodococcus equi by assaying for high-affinity hydrogenase (hhyL) genes and quantifying H2 uptake rates. We find that aerial structures (hyphae and spores) are important for Streptomyces H2 consumption; uptake was not observed in S. griseoflavus Tu4000 (deficient in aerial structures) and was reduced by physical disruption of Streptomyces sp. HFI8 aerial structures. H2 consumption depended on the life cycle stage in developmentally distinct actinobacteria: Streptomyces sp. HFI8 (sporulating) and R. equi (non-sporulating, non-filamentous). Strain HFI8 took up H2 only after forming aerial hyphae and sporulating, while R. equi only consumed H2 in the late exponential and stationary phase. These observations suggest that conditions favouring H2 uptake by actinobacteria are associated with energy and nutrient limitation. Thus, H2 may be an important energy source for soil microorganisms inhabiting systems in which nutrients are frequently limited. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

  20. (abstract) Line Mixing Behavior of Hydrogen-Broadened Ammonia Under Jovian Atmospheric Conditions

    NASA Technical Reports Server (NTRS)

    Spilker, Thomas R.

    1994-01-01

    Laboratory spectral data reported last year have been used to investigate the line mixing behavior of hydrogen-broadened ammonia inversion lines. The data show that broadening parameters appearing in the modified Ben-Reuven opacity formalism of Berge and Gulkis (1976) cannot maintain constant values over pressure ranges that include low to moderate pressures and high pressures. Also, they cannot change drastically in value, as in the Spilker (1990) revision of the Berge and Gulkis formalism. It has long been recognized that at low pressures, less than about 1 bar of a Jovian atmospheric mixture, a VVW formalism yields more accurate predictions of ammonia opacity than Ben-Reuven formalisms. At higher pressures the Ben-Reuven formalisms are more accurate. Since the Ben-Reuven lineshape collapses to a VVW lineshape in the low pressure limit, this low pressure inaccuracy of the Ben-Reuven formalisms is surprising. By incorporating various behavior, a new formalism is produced that is more accurate than previous formalisms, particularly in the critical 'transition region' from 0.5 to 2 bars, and that can be used without discontinuity from pressures of zero to hundreds of bars. The new formalism will be useful in such applications as interpretation of radio astronomical and radio occultation data on giant planet atmospheres, and radiative transfer modeling of those atmospheres.

  1. Effects of hydrogen peroxide, modified atmosphere and their combination on quality of minimally processed cluster beans.

    PubMed

    Waghmare, Roji B; Annapure, Uday S

    2017-10-01

    The aim of this study was to determine the potential of hydrogen peroxide (H 2 O 2 ) and modified atmosphere packaging (MAP) on quality of fresh-cut cluster beans. Fresh-cut cluster beans were dipped in a solution of 2% H 2 O 2 for 2 min, packed in an atmosphere of (5% O 2 , 10% CO 2 , 85% N 2 ) and stored in polypropylene bags at 5 °C for 35 days. Passive MAP was created by consuming O 2 and producing CO 2 by fresh-cut cluster beans. The combined effect of H 2 O 2 and MAP on physico-chemical analysis (Headspace gas, weight loss, chlorophyll, hardness and color), microbial quality (mesophilic aerobics and yeasts and molds) and sensory analysis were studied. Chemical treatment and MAP both are equally effective in extending the shelf life at 5 °C for 28 days. Hence, MAP can be an alternative for chemical treatment to achieve a shelf life of 28 days for fresh-cut cluster beans. Control samples, without chemical treatment and modified atmosphere, stored at 5 °C were spoiled after 14 days. Chemical treatment followed by MAP underwent minimum changes in weight, chlorophyll, hardness and color of fresh-cut cluster beans. Combination treatment gives a storage life of 35 days.

  2. Studies of Evaluation of Hydrogen Embrittlement Property of High-Strength Steels with Consideration of the Effect of Atmospheric Corrosion

    NASA Astrophysics Data System (ADS)

    Akiyama, Eiji; Wang, Maoqiu; Li, Songjie; Zhang, Zuogui; Kimura, Yuuji; Uno, Nobuyoshi; Tsuzaki, Kaneaki

    2013-03-01

    Hydrogen embrittlement of high-strength steels was investigated by using slow strain rate test (SSRT) of circumferentially notched round bar specimens after hydrogen precharging. On top of that, cyclic corrosion tests (CCT) and outdoor exposure tests were conducted prior to SSRT to take into account the effect of hydrogen uptake under atmospheric corrosion for the evaluation of the susceptibility of high-strength steels. Our studies of hydrogen embrittle properties of high-strength steels with 1100 to 1500 MPa of tensile strength and a prototype ultrahigh-strength steel with 1760 MPa containing hydrogen traps using those methods are reviewed in this article. A power law relationship between notch tensile strength of hydrogen-precharged specimens and diffusible hydrogen content has been found. It has also been found that the local stress and the local hydrogen concentration are controlling factors of fracture. The results obtained by using SSRT after CCT and outdoor exposure test were in good agreement with the hydrogen embrittlement fracture property obtained by means of long-term exposure tests of bolts made of the high-strength steels.

  3. Thermodynamic analysis of chemical stability of ceramic materials in hydrogen-containing atmospheres at high temperatures

    NASA Technical Reports Server (NTRS)

    Misra, Ajay K.

    1990-01-01

    The chemical stability of several ceramic materials in hydrogen-containing environments was analyzed with thermodynamic considerations in mind. Equilibrium calculations were made as a function of temperature, moisture content, and total system pressure. The following ceramic materials were considered in this study: SiC, Si3N4, SiO2, Al2O3, mullite, ZrO2, Y2O3, CaO, MgO, BeO, TiB2, TiC, HfC, and ZrC. On the basis of purely thermodynamic arguments, upper temperature limits are suggested for each material for long-term use in H2-containing atmospheres.

  4. Atmospheric Hydrogen (H2) Concentrations from the CSIRO GASLAB Flask Sampling Network (1992 - 2001)

    DOE Data Explorer

    Steele, L. P. [Commonwealth Scientific and Industrial Research Organization (CSIRO), Atmospheric Research, Aspendale, Victoria, Australia; Krummel, P. B. [Commonwealth Scientific and Industrial Research Organization (CSIRO), Atmospheric Research, Aspendale, Victoria, Australia; Langenfelds, R. L. [Commonwealth Scientific and Industrial Research Organization (CSIRO), Atmospheric Research, Aspendale, Victoria, Australia

    2003-01-01

    Air samples from nine sites were collected from the CSIRO GASLAB Flask Sampling Network for the purpose of monitoring the atmospheric hydrogen (H2) concentrations. The listed data were obtained from flask air samples returned to the CSIRO GASLAB for analysis. Typical sample storage times ranged from days to weeks for some sites (e.g., Cape Grim) to as much as one year for Macquarie Island and the Antarctic sites. Experiments carried out to test for any change in sample H22 mixing ratio during storage have shown no consistent and systematic drift in these flask types over test periods of several months to years (Cooper et al., 1999). An annual cycle of H2 is evident, reflecting the seasonal nature of some of the major sources and sinks (Novelli et al., 1999).

  5. A probabilistic approach to radiative energy loss calculations for optically thick atmospheres - Hydrogen lines and continua

    NASA Technical Reports Server (NTRS)

    Canfield, R. C.; Ricchiazzi, P. J.

    1980-01-01

    An approximate probabilistic radiative transfer equation and the statistical equilibrium equations are simultaneously solved for a model hydrogen atom consisting of three bound levels and ionization continuum. The transfer equation for L-alpha, L-beta, H-alpha, and the Lyman continuum is explicitly solved assuming complete redistribution. The accuracy of this approach is tested by comparing source functions and radiative loss rates to values obtained with a method that solves the exact transfer equation. Two recent model solar-flare chromospheres are used for this test. It is shown that for the test atmospheres the probabilistic method gives values of the radiative loss rate that are characteristically good to a factor of 2. The advantage of this probabilistic approach is that it retains a description of the dominant physical processes of radiative transfer in the complete redistribution case, yet it achieves a major reduction in computational requirements.

  6. Finite element modeling and numerical simulation of sintered tungsten components under hydrogen atmosphere

    NASA Astrophysics Data System (ADS)

    Mamen, B.; Song, J.; Barriere, T.; Gelin, J.-C.

    2013-05-01

    Powder injection molding (PIM) is a suitable technology for manufacturing of complex shapes with tungsten powders and has a great potential in many applications. Sintering is one of the most important steps in Powder Injection Molding process. The sintering behaviour of tungsten injection moulded components, under pure hydrogen atmosphere at temperature up to 1700°C using fine 0.4μm and coarse powders 7.0 μm, is investigated by means of the beam bending and dilatometric tests in the Setaram{copyright, serif} analyser. To simulate the shrinkage and shape distortion of tungsten injection moulded components during the sintering process using finite element methods, viscoplastic constitutive law is implemented in ABAQUS software as user subroutine UMAT and incorporated with the identified parameters. Comparison between the numerical simulations results and experimental ones, in term of shrinkages and sintered densities, shows good agreement between the two.

  7. Photocatalytic hydrogen evolution of palladium nanoparticles decorated black TiO2 calcined in argon atmosphere

    NASA Astrophysics Data System (ADS)

    Wu, Ming-Chung; Hsiao, Kai-Chi; Chang, Yin-Hsuan; Chan, Shun-Hsiang

    2018-02-01

    Black TiO2 nanoparticles (BTN) was prepared by sol-gel derived precursor calcined in an argon atmosphere. The synthesized BTN with trivalent titanium ion, structural defect, and oxygen vacancy shows a remarkably high absorbance in the visible light spectrum. BTN thus behaves a higher visible-active nanoreactor than white TiO2 nanoparticles (WTN) in the aqueous solution for organic pollutant degradation. Moreover, palladium decoration on the BTN surface (Pd-BTN) demonstrates a fascinating clean energy application. The obtained Pd-BTN fulfills a satisfied green material demand in the photocatalytic hydrogen production application. Pd-BTN calcined at 400 °C (Pd-BTN-400) shows the high photocatalytic hydrogen generation rate of 5200 μmol/g h under UV-A irradiation and 9300 μmol/g h under UV-B irradiation, respectively. The well-developed material, Pd-BTN-400, could be one of the best solutions in the concern of clean energy and water-purification with regard to the continuous environmental issue.

  8. A gas chromatographic instrument for measurement of hydrogen cyanide in the lower atmosphere

    NASA Astrophysics Data System (ADS)

    Ambrose, J. L.; Zhou, Y.; Haase, K.; Mayne, H. R.; Talbot, R.; Sive, B. C.

    2012-01-01

    A gas-chromatographic (GC) instrument was developed for measuring hydrogen cyanide (HCN) in the lower atmosphere. The main features of the instrument are (1) a cryogen-free cooler for sample dehumidification and enrichment, (2) a porous polymer PLOT column for analyte separation, (3) a flame thermionic detector (FTD) for sensitive and selective detection and (4) a dynamic dilution system for calibration. We deployed the instrument for a ~4 month period from January-June 2010 at the AIRMAP atmospheric monitoring station Thompson Farm 2 (THF2) in rural Durham, NH. A subset of measurements made during 3-31 March is presented here with a detailed description of the instrument features and performance characteristics. The temporal resolution of the measurements was ~20 min, with a 75 s sample capture time. The 1σ measurement precision was <10% and the instrument response linearity was excellent on a calibration scale of 0.10-0.75 ppbv (±5%). The estimated method detection limit (MDL) and accuracy were 0.021 ppbv and 15%, respectively. From 3-31 March 2010, ambient HCN mixing ratios ranged from 0.15-1.0 ppbv (±15%), with a mean value of 0.36 ± 0.16 ppbv (1σ). The approximate mean background HCN mixing ratio of 0.20 ± 0.04 ppbv appeared to agree well with tropospheric column measurements reported previously. The GC-FTD HCN measurements were strongly correlated with acetonitrile (CH3CN) measured concurrently with a proton transfer-reaction mass spectrometer (PTR-MS), as anticipated given our understanding that the nitriles share a common primary biomass burning source to the global atmosphere. The nitriles were overall only weakly correlated with CO, which is reasonable considering the greater diversity of sources for CO. However, strong correlations with CO were observed on several nights under stable atmospheric conditions and suggest regional combustion-based sources for the nitriles. These results demonstrate that the GC-FTD instrument is capable of making long

  9. A gas chromatographic instrument for measurement of hydrogen cyanide in the lower atmosphere

    NASA Astrophysics Data System (ADS)

    Ambrose, J. L.; Zhou, Y.; Haase, K.; Mayne, H. R.; Talbot, R.; Sive, B. C.

    2012-06-01

    A gas-chromatographic (GC) instrument was developed for measuring hydrogen cyanide (HCN) in the lower atmosphere. The main features of the instrument are (1) a cryogen-free cooler for sample dehumidification and enrichment, (2) a porous polymer PLOT column for analyte separation, (3) a flame thermionic detector (FTD) for sensitive and selective detection, and (4) a dynamic dilution system for calibration. We deployed the instrument for a ∼4 month period from January-June, 2010 at the AIRMAP atmospheric monitoring station Thompson Farm 2 (THF2) in rural Durham, NH. A subset of measurements made during 3-31 March is presented here with a detailed description of the instrument features and performance characteristics. The temporal resolution of the measurements was ~20 min, with a 75 s sample capture time. The 1σ measurement precision was <10% and the instrument response linearity was excellent on a calibration scale of 0.10-0.75 ppbv (±5%). The estimated method detection limit (MDL) and accuracy were 0.021 ppbv and 15%, respectively. From 3-31 March 2010, ambient HCN mixing ratios ranged from 0.15-1.0 ppbv (±15%), with a mean value of 0.36 ± 0.16 ppbv (1σ). The approximate mean background HCN mixing ratio of 0.20 ± 0.04 ppbv appeared to agree well with tropospheric column measurements reported previously. The GC-FTD HCN measurements were strongly correlated with acetonitrile (CH3CN) measured concurrently with a proton transfer-reaction mass spectrometer (PTR-MS), as anticipated given our understanding that the nitriles share a common primary biomass burning source to the global atmosphere. The nitriles were overall only weakly correlated with carbon monoxide (CO), which is reasonable considering the greater diversity of sources for CO. However, strong correlations with CO were observed on several nights under stable atmospheric conditions and suggest regional combustion-based sources for the nitriles. These results demonstrate that the GC-FTD instrument is

  10. Hydrogen Isotopic Composition of Water in the Martian Atmosphere and Released from Rocknest Fines

    NASA Technical Reports Server (NTRS)

    Leshin, L. A.; Webster, C. R.; Mahaffy, P. R.; Flesh, G. J.; Christensen, L. E.; Stern, J. C.; Franz, H. B.; McAdam, A. C.; Niles, P. B.; Archer, P. B., Jr.; hide

    2013-01-01

    The Mars Science Laboratory Curiosity rover sampled the aeolian bedform called Rocknest as its first solid samples to be analyzed by the analytical instruments CheMin and SAM. The instruments ingested aliquots from a sieved sample of less than 150 micrometer grains. As discussed in other reports at this conference [e.g., 1], CheMin discovered many crystalline phases, almost all of which are igneous minerals, plus some 10s of percent of x-ray amorphous material. The SAM instrument is focused on understanding volatiles and possible organics in the fines, performing evolved gas analysis (EGA) with the SAM quadrapole mass spectrometer (QMS), isotope measurements using both the QMS and the tunable laser spectrometer (TLS), which is sensitive to CO2, water and methane, and organics with the gas chromatograph mass spectrometer (GCMS). As discussed in the abstract by Franz et al. [2] and others, EGA of Rocknest fines revealed the presence of significant amounts of H2O as well as O-, C- and S-bearing materials. SAM has also tasted the martian atmosphere several times, analyzing the volatiles in both the TLS and QMS [e.g., 3,4]. This abstract will focus on presentation of initial hydrogen isotopic data from the TLS for Rocknest soils and the atmosphere, and their interpretation. Data for CO2 isotopes and O isotopes in water are still being reduced, but should be available by at the conference.

  11. XUV-Exposed, Non-Hydrostatic Hydrogen-Rich Upper Atmospheres of Terrestrial Planets. Part II: Hydrogen Coronae and Ion Escape

    PubMed Central

    Lammer, Helmut; Holmström, Mats; Panchenko, Mykhaylo; Odert, Petra; Erkaev, Nikolai V.; Leitzinger, Martin; Khodachenko, Maxim L.; Kulikov, Yuri N.; Güdel, Manuel; Hanslmeier, Arnold

    2013-01-01

    Abstract We studied the interactions between the stellar wind plasma flow of a typical M star, such as GJ 436, and the hydrogen-rich upper atmosphere of an Earth-like planet and a “super-Earth” with a radius of 2 REarth and a mass of 10 MEarth, located within the habitable zone at ∼0.24 AU. We investigated the formation of extended atomic hydrogen coronae under the influences of the stellar XUV flux (soft X-rays and EUV), stellar wind density and velocity, shape of a planetary obstacle (e.g., magnetosphere, ionopause), and the loss of planetary pickup ions on the evolution of hydrogen-dominated upper atmospheres. Stellar XUV fluxes that are 1, 10, 50, and 100 times higher compared to that of the present-day Sun were considered, and the formation of high-energy neutral hydrogen clouds around the planets due to the charge-exchange reaction under various stellar conditions was modeled. Charge-exchange between stellar wind protons with planetary hydrogen atoms, and photoionization, lead to the production of initially cold ions of planetary origin. We found that the ion production rates for the studied planets can vary over a wide range, from ∼1.0×1025 s−1 to ∼5.3×1030 s−1, depending on the stellar wind conditions and the assumed XUV exposure of the upper atmosphere. Our findings indicate that most likely the majority of these planetary ions are picked up by the stellar wind and lost from the planet. Finally, we estimated the long-time nonthermal ion pickup escape for the studied planets and compared them with the thermal escape. According to our estimates, nonthermal escape of picked-up ionized hydrogen atoms over a planet's lifetime within the habitable zone of an M dwarf varies between ∼0.4 Earth ocean equivalent amounts of hydrogen (EOH) to <3 EOH and usually is several times smaller in comparison to the thermal atmospheric escape rates. Key Words: Stellar activity—Low-mass stars—Early atmospheres—Earth-like exoplanets—Energetic neutral

  12. XUV-exposed, non-hydrostatic hydrogen-rich upper atmospheres of terrestrial planets. Part II: hydrogen coronae and ion escape.

    PubMed

    Kislyakova, Kristina G; Lammer, Helmut; Holmström, Mats; Panchenko, Mykhaylo; Odert, Petra; Erkaev, Nikolai V; Leitzinger, Martin; Khodachenko, Maxim L; Kulikov, Yuri N; Güdel, Manuel; Hanslmeier, Arnold

    2013-11-01

    We studied the interactions between the stellar wind plasma flow of a typical M star, such as GJ 436, and the hydrogen-rich upper atmosphere of an Earth-like planet and a "super-Earth" with a radius of 2 R(Earth) and a mass of 10 M(Earth), located within the habitable zone at ∼0.24 AU. We investigated the formation of extended atomic hydrogen coronae under the influences of the stellar XUV flux (soft X-rays and EUV), stellar wind density and velocity, shape of a planetary obstacle (e.g., magnetosphere, ionopause), and the loss of planetary pickup ions on the evolution of hydrogen-dominated upper atmospheres. Stellar XUV fluxes that are 1, 10, 50, and 100 times higher compared to that of the present-day Sun were considered, and the formation of high-energy neutral hydrogen clouds around the planets due to the charge-exchange reaction under various stellar conditions was modeled. Charge-exchange between stellar wind protons with planetary hydrogen atoms, and photoionization, lead to the production of initially cold ions of planetary origin. We found that the ion production rates for the studied planets can vary over a wide range, from ∼1.0×10²⁵ s⁻¹ to ∼5.3×10³⁰ s⁻¹, depending on the stellar wind conditions and the assumed XUV exposure of the upper atmosphere. Our findings indicate that most likely the majority of these planetary ions are picked up by the stellar wind and lost from the planet. Finally, we estimated the long-time nonthermal ion pickup escape for the studied planets and compared them with the thermal escape. According to our estimates, nonthermal escape of picked-up ionized hydrogen atoms over a planet's lifetime within the habitable zone of an M dwarf varies between ∼0.4 Earth ocean equivalent amounts of hydrogen (EO(H)) to <3 EO(H) and usually is several times smaller in comparison to the thermal atmospheric escape rates.

  13. Preconditioning of the YSZ-NiO Fuel Cell Anode in Hydrogenous Atmospheres Containing Water Vapor.

    PubMed

    Vasyliv, Bogdan; Podhurska, Viktoriya; Ostash, Orest

    2017-12-01

    The YSZ-NiO ceramics for solid oxide fuel cells (SOFCs) anode have been investigated. A series of specimens were singly reduced in a hydrogenous atmosphere (Ar-5 vol% H 2 mixture) at 600 °C under the pressure of 0.15 MPa or subjected to 'reduction in the mixture-oxidation in air' (redox) cycling at 600 °C. The YSZ-Ni cermets formed in both treatment conditions were then aged in 'water vapor in Ar-5 vol% H 2 mixture' atmosphere at 600 °C under the pressure of 0.15 MPa. Additionally, the behaviour of the as-received material in this atmosphere was studied. It was revealed that small amount of water vapor in Ar-5 vol% H 2 mixture (water vapor pressure below 0.03 MPa) does not affect the reduction of the nickel phase in the YSZ-NiO ceramics, but causes some changes in the YSZ-Ni cermet structure. In particular, nanopore growth in tiny Ni particles takes place. At higher concentration of water vapor in the mixture (water vapor pressure above 0.03-0.05 MPa), converse changes in the kinetics of reduction occur. The best physical and mechanical properties were revealed for the material treated by redox cycling after holding at 600 °C in water depleted gas mixture. The dual effect of water vapor on nickel-zirconia anode behaviour is discussed basing on scanning electron microscopy analysis data, material electrical conductivity, and strength.

  14. Early Evolution of Water D/H in a Hydrogen-rich Proto-atmosphere on the Earth

    NASA Astrophysics Data System (ADS)

    Genda, H.; Ikoma, M.

    2005-08-01

    The origin of the Earth's ocean has been investigated by examining deuterium/hydrogen ratios (D/H) of various sources of water such as water-rich meteorites (e.g., Carbonaceous Chondrites: CC), comets, and the solar nebula. The average D/H of CC is very similar to the current D/H of the Earth's ocean. On the other hand, D/H of comets are larger by about a factor of two than one of the Earth's ocean, and D/H of the solar nebula is smaller by about a factor of seven. Consequently, the main source of the Earth's ocean has been though to be CC or adequate mixing of comets and the solar nebula. However, it is not clear that D/H of a water source is preserved during the formation of the ocean and/or evolution of the ocean and atmosphere. In the atmosphere on the early Earth, a significant amount of hydrogen likely existed because of gravitational attraction of the surrounding solar nebula or reduction of water in the presence of metallic Fe. In that situation, water is enriched in deuterium by the isotopic exchange reaction between water and hydrogen molecules. Moreover, the hydrogen-rich atmosphere also becomes rich in deuterium due to mass fractionation by hydrodynamic hydrogen escape, resulting in further deuterium enrichment of water. Here, we will present the D/H evolution of the ocean and the hydrogen-rich proto-atmosphere, and constrain the water source of the ocean. This research was supported by a JSPS Research Fellowship and the 21st Century COE Program ``How to build habitable planets", Tokyo Institute of Technology, sponsored by the Ministry of Education, Culture, Sports, Technology and Science (MEXT) Japan.

  15. The Role of Hydrogen in Determining the Stability of CO2 Atmospheres of Terrestrial Exoplanets Around M Dwarfs

    NASA Astrophysics Data System (ADS)

    Gao, Peter; Hu, Renyu; Robinson, Tyler D.; Yung, Yuk L.

    2014-11-01

    The recent discovery of terrestrial worlds in the Habitable Zones of M Dwarfs necessitates a more intensive investigation of the properties of these planets. One major feature of certain M Dwarfs is their high fluxes of EUV radiation, which photolyzes CO2, an important greenhouse gas that should be abundant on rocky worlds. This photolytic destruction of CO2 can be countered by HOx chemistry: photolysis of HOx species by NUV radiation generates OH, which reacts with CO to regenerate CO2. These processes are balanced around Sun-like stars such that Venus and Mars can maintain CO2-dominated atmospheres. However, M Dwarfs tend to have much lower NUV/EUV flux ratios, which could prevent the formation of significant CO2 atmospheres on any planets they may host. In this study, we evaluate the properties of CO2 atmospheres surrounding an Earth-massed, Earth-sized exoplanet in orbit of an M Dwarf using a 1D photochemical kinetics model. We consider an atmosphere similar in composition to that of Mars, but scaled to have a surface pressure of 1 bar. We choose to focus on Mars-like atmospheres rather than Earth-like ones, as Earth's atmosphere has been altered through biological sources and sinks and the presence of a large liquid water ocean, which are not necessarily present on terrestrial exoplanets. Our preliminary results show that the hydrogen content of the atmosphere is crucial in determining the ratio of CO2 to CO and O2. In particular, for a H2 mixing ratio identical to that of Mars 20-30 ppm), a steady state atmosphere is reached after 10 Gyr consisting of ~85% CO2, ~10% CO, and ~5% O2, with an ozone mixing ratio of ~0.01 ppm. In the extreme case where all hydrogen is lost to space, an atmosphere consisting of ~64% CO2, ~24% CO, and 12% O2 results, while ozone levels reach ~10 ppm. Finally, for H2 mixing ratios similar to that of Earth 0.5 ppm) and no atmospheric escape, a 49% CO2, 34% CO, 17% O2, and 0.1 ppm O3 atmosphere is possible. This not only points to the

  16. Coupled Oxygen and Hydrogen Isotope Analysis of Water Along the Soil-Plant- Atmosphere Continuum

    NASA Astrophysics Data System (ADS)

    Huang, Z.; Webb, E. A.; Longstaffe, F. J.

    2008-12-01

    The oxygen and hydrogen isotope compositions of water within a plant vary with transpiration rates and the isotopic composition of soil water. Both of these parameters are affected by temperature and relative humidity. A controlled-temperature, growth-chamber experiment was conducted to determine the relationships among temperature, relative humidity, soil water evaporation and plant-water isotope composition in cattails and horsetails. Typha, a cattail species that grows in wetland conditions, and Equisetum, a horsetail species that prefers dry soils, were each grown in four chambers at 15, 20, 25 and 30 degrees Celsius. The oxygen and hydrogen isotope compositions of watering water, soil water, vapour in the growth chambers and plant water from the leaves and stems were analyzed throughout the eight-month long artificial growing season. Although the oxygen isotope composition of the watering water remained constant, the soil water, atmospheric vapour and plant water were progressively enriched in oxygen-18 and deuterium in each of the four chambers from low to high temperatures as a result of increasing evaporation. The oxygen isotope composition of plant water along the length of a single stem or leaf was increasingly enriched in the heavier isotopes towards the apex. There was no significant difference in the magnitude of this trend between species. These results indicate that the isotopic composition of plant water is primarily controlled by environmental conditions. The oxygen isotope composition of the water vapour in the growing chamber increased with temperature, consistent with equilibration between the vapour and the oxygen-18 enriched soil and plant water reservoirs. The magnitude and interaction of these variables, as measured for these modern samples of cattails and horsetails, should be useful in calibrating paleoclimate proxies based on fossilized plant materials (e.g., cellulose, phytoliths).

  17. Meridional distribution of molecular hydrogen and its deuterium content in the atmosphere

    NASA Astrophysics Data System (ADS)

    Rice, Andrew; Quay, Paul; Stutsman, Johnny; Gammon, Richard; Price, Heather; Jaeglé, Lyatt

    2010-06-01

    The atmospheric molecular hydrogen concentration and its deuterium abundance were measured in remote air samples collected onboard six Pacific Ocean ship transects between 37°N and 77°S during years 2001 through 2005. The data reveal a year-round interhemispheric gradient in H2 concentration and isotopic composition with the extratropical Northern Hemisphere lower in H2 concentration by 17 ± 11 ppb and δD of H2 by 16 ± 12‰ than the Southern Hemisphere (95% confidence). On the basis of these snapshots, the interhemispheric gradient in δD was observed to be smallest in September through November, a time that experiences the largest gradient in concentration, and the largest in April, a time that has a small gradient in concentration. A simple hemispheric box model of the atmosphere indicates that, while the hemispheric asymmetry in soil sink of H2 is primarily responsible for the observed interhemispheric gradient in H2 concentration, the hemispheric difference in the δD of the H2 sources and sinks are equally responsible for the observed interhemispheric gradient in δD. Both the inverse correlation between interhemispheric H2 and δD gradients and their seasonal changes point to the importance of the H2 produced by photochemical sources. Comparisons with a three-dimensional chemical transport model shows reasonable agreement with mean behavior in both variables and provides an accounting for H2 sources and sinks within ±15% without a dramatic change in the H2 budget. Anomalous H2 concentrations and δD in tropics and low-latitude regions observed during the November-December 2001 meridional H2 and δD snapshot is thought to be a result of H2 emissions from biomass burning, possibly from continental Africa.

  18. Kinetic Modeling of a Silicon Refining Process in a Moist Hydrogen Atmosphere

    NASA Astrophysics Data System (ADS)

    Chen, Zhiyuan; Morita, Kazuki

    2018-03-01

    We developed a kinetic model that considers both silicon loss and boron removal in a metallurgical grade silicon refining process. This model was based on the hypotheses of reversible reactions. The reaction rate coefficient kept the same form but error of terminal boron concentration could be introduced when relating irreversible reactions. Experimental data from published studies were used to develop a model that fit the existing data. At 1500 °C, our kinetic analysis suggested that refining silicon in a moist hydrogen atmosphere generates several primary volatile species, including SiO, SiH, HBO, and HBO2. Using the experimental data and the kinetic analysis of volatile species, we developed a model that predicts a linear relationship between the reaction rate coefficient k and both the quadratic function of p(H2O) and the square root of p(H2). Moreover, the model predicted the partial pressure values for the predominant volatile species and the prediction was confirmed by the thermodynamic calculations, indicating the reliability of the model. We believe this model provides a foundation for designing a silicon refining process with a fast boron removal rate and low silicon loss.

  19. Measurements of atmospheric dimethylsulfide, hydrogen sulfide, and carbon disulfide during GTE/CITE 3

    NASA Astrophysics Data System (ADS)

    Cooper, David J.; Saltzman, Eric S.

    1993-12-01

    Measurements of atmospheric dimethylsulfide (DMS), hydrogen sulfide (H2S), and carbon disulfide (CS2) were made over the North and South Atlantic Ocean as part of the Global Tropospheric Experiment/Chemical Instrumentation Test and Evaluation (GTE/CITE 3) project. DMS and CS2 samples were collected and analyzed using an automated gas chromatography/flame photometric detection system with a sampling frequency of 10 min. H2S samples were collected using silver nitrate impregnated filters and analyzed by fluorescence quenching. The DMS data from both hemispheres have a bimodal distribution. Over the North Atlantic this reflects the difference between marine and continental air masses. Over the South Atlantic it may reflect differences in the sea surface source of DMS, corresponding to different air mass source regions. The median boundary layer H2S and CS2 levels were significantly higher in the northern hemisphere than the southern hemisphere, reflecting the higher frequency of samples influenced by pollutant and/or coastal emissions. Composite vertical profiles of DMS and H2S are similar to each other, and are consistent with a sea surface source. Vertical profiles of CS2 have maxima in the free troposphere, implicating a continental source. The low levels of H2S and CS2 found in the southern hemisphere constrain the role of these compounds in global budgets to significantly less than previously estimated.

  20. Production of Hydrogen and Carbon Nanotube by direct decomposition of methane using pulsed corona discharge under th atmospheric pressure.

    NASA Astrophysics Data System (ADS)

    Nath Mishra, Lekha; Shibata, Kanetoshi; Ito, Hiroaki; Yugami, Noboru; Nishida, Yasushi

    2003-10-01

    In future, hydrogen is supposed to play an important role in the worldwide energy supply. It allows a more efficient utilization of fossil fuels and the reduction of noxoous emissions, e.g. by fuel cells or the use of hydrogen enriched fuels in the combustion engines or gas turbines. Plasma methods are expected to allow low temperature and fuel flexible on-site hydrogen generation. Experiments are performed to develop a pulsed corona discharge system for the production of hydrogen and carbon nanotubes by direct methane decomposition under the atmospheric pressure. The corona discharge is energized by 10-20μs wide voltage pulses (≤7kV) at a repetition rate of 0-5000 pulses per second. The spectrum of the gas is carried out by Mass Spectrometer. Experimentally, it is shown that the production of hydrogen gas depends on the pulsed width, input voltage, frequency, current and discharge time. The spectrum noted by the Mass Spectrometer is also presented. The structural geometry of the carbon nanotube is observed by Transmission Electron Microscope (TEM) and Scanig Electron Microscopy (SEM). The soot for this purpose is collected from the cathode. Different lengths noted for different soot collected from different parts with the help of TEM are also presented. The present experimental technique could be applicable for the future energy source using hydrogen and the nanoelectronics.

  1. XUV-Exposed, Non-Hydrostatic Hydrogen-Rich Upper Atmospheres of Terrestrial Planets. Part I: Atmospheric Expansion and Thermal Escape

    PubMed Central

    Lammer, Helmut; Odert, Petra; Kulikov, Yuri N.; Kislyakova, Kristina G.; Khodachenko, Maxim L.; Güdel, Manuel; Hanslmeier, Arnold; Biernat, Helfried

    2013-01-01

    Abstract The recently discovered low-density “super-Earths” Kepler-11b, Kepler-11f, Kepler-11d, Kepler-11e, and planets such as GJ 1214b represent the most likely known planets that are surrounded by dense H/He envelopes or contain deep H2O oceans also surrounded by dense hydrogen envelopes. Although these super-Earths are orbiting relatively close to their host stars, they have not lost their captured nebula-based hydrogen-rich or degassed volatile-rich steam protoatmospheres. Thus, it is interesting to estimate the maximum possible amount of atmospheric hydrogen loss from a terrestrial planet orbiting within the habitable zone of late main sequence host stars. For studying the thermosphere structure and escape, we apply a 1-D hydrodynamic upper atmosphere model that solves the equations of mass, momentum, and energy conservation for a planet with the mass and size of Earth and for a super-Earth with a size of 2 REarth and a mass of 10 MEarth. We calculate volume heating rates by the stellar soft X-ray and extreme ultraviolet radiation (XUV) and expansion of the upper atmosphere, its temperature, density, and velocity structure and related thermal escape rates during the planet's lifetime. Moreover, we investigate under which conditions both planets enter the blow-off escape regime and may therefore experience loss rates that are close to the energy-limited escape. Finally, we discuss the results in the context of atmospheric evolution and implications for habitability of terrestrial planets in general. Key Words: Stellar activity—Low-mass stars—Early atmospheres—Earth-like exoplanets—Energetic neutral atoms—Ion escape—Habitability. Astrobiology 13, 1011–1029. PMID:24251443

  2. XUV-exposed, non-hydrostatic hydrogen-rich upper atmospheres of terrestrial planets. Part I: atmospheric expansion and thermal escape.

    PubMed

    Erkaev, Nikolai V; Lammer, Helmut; Odert, Petra; Kulikov, Yuri N; Kislyakova, Kristina G; Khodachenko, Maxim L; Güdel, Manuel; Hanslmeier, Arnold; Biernat, Helfried

    2013-11-01

    The recently discovered low-density "super-Earths" Kepler-11b, Kepler-11f, Kepler-11d, Kepler-11e, and planets such as GJ 1214b represent the most likely known planets that are surrounded by dense H/He envelopes or contain deep H₂O oceans also surrounded by dense hydrogen envelopes. Although these super-Earths are orbiting relatively close to their host stars, they have not lost their captured nebula-based hydrogen-rich or degassed volatile-rich steam protoatmospheres. Thus, it is interesting to estimate the maximum possible amount of atmospheric hydrogen loss from a terrestrial planet orbiting within the habitable zone of late main sequence host stars. For studying the thermosphere structure and escape, we apply a 1-D hydrodynamic upper atmosphere model that solves the equations of mass, momentum, and energy conservation for a planet with the mass and size of Earth and for a super-Earth with a size of 2 R(Earth) and a mass of 10 M(Earth). We calculate volume heating rates by the stellar soft X-ray and extreme ultraviolet radiation (XUV) and expansion of the upper atmosphere, its temperature, density, and velocity structure and related thermal escape rates during the planet's lifetime. Moreover, we investigate under which conditions both planets enter the blow-off escape regime and may therefore experience loss rates that are close to the energy-limited escape. Finally, we discuss the results in the context of atmospheric evolution and implications for habitability of terrestrial planets in general.

  3. Stable hydrogen isotope composition of n-alkanes in urban atmospheric aerosols in Taiyuan, China

    NASA Astrophysics Data System (ADS)

    Bai, Huiling; Li, Yinghui; Peng, Lin; Liu, Xiangkai; Liu, Xiaofeng; Song, Chongfang; Mu, Ling

    2017-03-01

    The hydrogen isotope compositions (δD) of n-alkanes associated with particulate matter with a diameter of ≤10 μm from Taiyuan, China, during heating and non-heating periods were measured via gas chromatography-isotope ratio mass spectrometry to reveal the spatial and temporal characteristics of five functional zones and to provide another constraint on atmospheric pollutants. The δD values of n-C16 to n-C31 during the heating and non-heating periods ranged from -235.9‰ to -119.8‰ and from -231.3‰ to -129.2‰, respectively, but these similar spans had different distribution features. During the heating period, the δD distributions between non-central heating and commercial districts were consistent, as were those between residential and industrial districts; the n-alkanes came from two or more types of emission sources. Coal soot might be the primary local emission source, but not the only source. During the non-heating period, the n-alkanes of n-C16 to n-C20 were more depleted in D with the increasing carbon number in all functional zones, but there was no rule for n-C21 to n-C31. Specifically, coal soot and vehicle exhaust might be the primary sources of n-alkanes for non-central heating districts in the heating and non-heating periods, respectively, according to the δD distribution of n-C18 to n-C22; gasoline vehicle exhaust might be an n-alkane source, and the hydrogen isotope fractionation effect during the condensation process should be a pollution mechanism for the commercial district during the heating period; the δD distribution difference of n-C16 to n-C18 between the two periods in the residential and industrial districts was consistent, which indicates a similar source of fossil fuel combustion and a similar isotope fractionation effect during the non-heating period.

  4. Pathways to Earth-like atmospheres. Extreme ultraviolet (EUV)-powered escape of hydrogen-rich protoatmospheres.

    PubMed

    Lammer, Helmut; Kislyakova, K G; Odert, P; Leitzinger, M; Schwarz, R; Pilat-Lohinger, E; Kulikov, Yu N; Khodachenko, M L; Güdel, M; Hanslmeier, M

    2011-12-01

    We discuss the evolution of the atmosphere of early Earth and of terrestrial exoplanets which may be capable of sustaining liquid water oceans and continents where life may originate. The formation age of a terrestrial planet, its mass and size, as well as the lifetime in the EUV-saturated early phase of its host star play a significant role in its atmosphere evolution. We show that planets even in orbits within the habitable zone of their host stars might not lose nebular- or catastrophically outgassed initial protoatmospheres completely and could end up as water worlds with CO2 and hydrogen- or oxygen-rich upper atmospheres. If an atmosphere of a terrestrial planet evolves to an N2-rich atmosphere too early in its lifetime, the atmosphere may be lost. We show that the initial conditions set up by the formation of a terrestrial planet and by the evolution of the host star's EUV and plasma environment are very important factors owing to which a planet may evolve to a habitable world. Finally we present a method for studying the discussed atmosphere evolution hypotheses by future UV transit observations of terrestrial exoplanets.

  5. The Reaction between Sodium Hydroxide and Atomic Hydrogen in Atmospheric and Flame Chemistry.

    PubMed

    Gómez Martín, J C; Seaton, C; de Miranda, M P; Plane, J M C

    2017-10-12

    We report the first direct kinetic study of the gas-phase reaction NaOH + H → Na + H 2 O, which is central to the chemistry of sodium in the upper atmosphere and in flames. The reaction was studied in a fast flow tube, where NaOH was observed by multiphoton ionization and time-of-flight mass spectrometry, yielding k(NaOH + H, 230-298 K) = (3.8 ± 0.8) × 10 -11 cm 3 molecule -1 s -1 (at 2σ confidence level), showing no significant temperature dependence over the indicated temperature range and essentially in agreement with previous estimates of the rate constant in hydrogen-rich flames. We show, using theoretical trajectory calculations, that the unexpectedly slow, yet T-independent, rate coefficient for NaOH + H is explained by severe constraints in the angle of attack that H can make on NaOH to produce H 2 O. This reaction is also central to explaining Na-catalyzed flame inhibition, which has been proposed to occur via the sequence Na + OH (+ M) → NaOH followed by NaOH + H → Na + H 2 O, thereby effectively recombinating H and OH to H 2 O. RRKM calculations for the recombination of Na and OH yield k(Na + OH + N 2 , 300-2400 K) = 2.7 × 10 -29 (300/T) 1.2 cm 6 molecule -2 s -1 , in agreement with a previous flash photolysis measurement at 653 K and Na-seeded flame studies in the 1800-2200 K range. These results therefore provide strong evidence to support the mechanism of flame inhibition by Na.

  6. Unraveling the oscillations of the richest pulsating hydrogen-atmosphere white dwarf

    NASA Astrophysics Data System (ADS)

    Hermes, JJ

    2016-10-01

    Most stars in our Galaxy will end or have already ended their lives as white dwarf stars, making them important benchmarks for stellar evolution. Here we propose to obtain COS far-ultraviolet spectroscopy of a pulsating hydrogen-atmosphere white dwarf (DAV) with extensive, space-based photometry obtained by the Kepler spacecraft during the K2 mission. The pulsation spectrum is the richest of any DAV collected to date, but to extract any information about the white dwarf interior we must identify the spherical degree (l) of the modes present. Our time-tagged ultraviolet observations will enable us to identify the spherical degree of the highest-amplitude pulsation modes, since the ratios of the ultraviolet-to-optical pulsation amplitudes strongly depend on the geometry of the pulsation modes. This will decisively determine if most of the modes present are a series of l=3 modes, as it appears from the frequency multiplets in the K2 data; however, l=3 modes have never been clearly identified in a pulsating white dwarf. Our far-ultraviolet spectroscopy, covering the H2/H2+ quasi-molecular satellites around 1400 and 1600 AA, will also measure the white dwarf temperature and mass to an accuracy unachievable from the ground. This robust temperature and mass will anchor our detailed asteroseismic investigation of this stellar remnant. The unique combination of HST and Kepler observations will make this white dwarf a benchmark for the unprecedented opportunities for white dwarf archaeology enabled by the original Kepler mission and its extension into the ecliptic, K2.

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

    NASA Technical Reports Server (NTRS)

    Zellner, Reinhard

    1990-01-01

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

  8. Stellar Driven Evolution of Hydrogen-Dominated Atmospheres from Earth-Like to Super-Earth-Type Exoplanets

    NASA Astrophysics Data System (ADS)

    Kislyakova, Kristina G.; Holmström, Mats; Lammer, Helmut; Erkaev, Nikolai V.

    In the present chapter we discuss the impact of a host stars radiation and plasma environment to the escape escape and evolution of hydrogen-dominated exoplanet atmospheres . We focus mainly on planets within the Earth- to super-Earth mass domain and consider both, thermal and nonthermal atmospheric escape processes. The type of thermal loss mechanism depends on the so-called escape parameter, which is the ratio of the gravitational energy of a particle to its thermal energy. For low values of this parameter a planetary atmosphere switches from classical Jeans to modified Jeans escape and finally to hydrodynamic blow off. During blow off the majority of the atmospheric particles dispose of enough energy to escape the planet's gravity field. This leads to extreme gas losses . It is shown that non-thermal losses for light species such as hydrogen never exceed blow off escape, but they are of significant importance for planets with relatively weak Jeans-type escape escape or heavier particles (e.g., O, C, N). From the diversity of non-thermal escape mechanisms, in the present chapter we focus on ion pick-up and discuss the importance of other loss mechanisms. The general conclusion of the chapter is, that escape processes strongly shape the evolution of exoplanet atmospheres and determine, if the planet loses its hydrogen and/or volatile-rich protoatmospheres or, on the contrary, remains as a mini-Neptune , which can probably not be considered as a potential habitat as we know it.

  9. Variability of Deuterium Fractionation Associated With Soil Uptake of Atmospheric Molecular Hydrogen

    NASA Astrophysics Data System (ADS)

    Rahn, T.; Randerson, J. T.; Eiler, J.

    2005-12-01

    Molecular hydrogen (H2) is the second most abundant reduced gas in the atmosphere (after methane) with a globally averaged mixing ratio of ~530 nmol/mol. Its largest sources are photochemical oxidation of methane and non-methane hydrocarbons with other recognized sources that include biomass burning, fossil fuel burning, nitrogen fixation, and ocean degassing. These sources are balanced by reaction of H2 with hydroxyl radicals (~25%) in the atmosphere and by deposition at the terrestrial soil surface (~75%). As with other atmospheric trace gases, the stable isotopic content of H2 has the potential to help quantify the various aspects of its production and destruction. The average deuterium content of H2 is dDH2 = ~130 ‰ relative to Standard Mean Ocean Water. While recent studies have begun to elucidate the deuterium content of the individual sources of H2 and the fractionation associated with hydroxyl oxidation has been well established in the laboratory, there are still few data documenting the fractionation associated with soil uptake. We measured the fractionation associated with soil uptake in May, June and August of 2002 in three upland ecosystems that were part of an Alaskan fire chronosequence. Fire occurred at these sites in 1999, 1987, and ~1920. Grasses and herbaceous vegetation establish initially after fire and are gradually replaced by deciduous trees and finally by evergreen trees and moss. All three sites were in interior Alaska near the town of Delta Junction (63° 54'N, 145° 40'W). Fluxes were measured with a Plexiglas flux chamber (8 liter volume) with a manifold of four ~400 ml double-valved glass flasks in parallel and a diaphragm pump for circulation (5 SLPM). Flasks were continuously flushed by the circulating system and isolated sequentially; they were then returned to the laboratory at Caltech for subsequent analysis. In the field, the chamber was seated on Plexiglas collars that were installed prior to initiating the study and left in

  10. Isotope composition of secondary hydrogen and helium above the atmosphere measured by the instruments NINA and NINA-2

    NASA Astrophysics Data System (ADS)

    Bidoli, V.; Casolino, M.; de Pascale, M.; Furano, G.; Iannucci, A.; Morselli, A.; Picozza, P.; Sparvoli, R.; Bakaldin, A.; Galper, A.; Koldashov, S.; Korotkov, M.; Leonov, A.; Mikhailov, V.; Voronov, S.; Boezio, M.; Bonvicini, V.; Vacchi, A.; Zampa, G.; Zampa, N.; Ambriola, M.; Cafagna, F.; Circella, M.; de Marzo, C.; Adriani, O.; Papini, P.; Spillantini, P.; Straulino, S.; Vannuccini, E.; Ricci, M.; Castellini, G.

    2003-05-01

    In this paper we report on the energy spectra and abundance ratios of hydrogen and helium isotopes of albedo origin, measured by the instruments NINA and NINA-2 in near-equatorial regions. The instrument NINA flew on board the satellite Resurs-01-N4 between 1998 and 1999, at a 830 km average altitude. The NINA-2 apparatus, on board the satellite MITA, was put into orbit in July 2000 at an altitude of about 450 km. NINA and NINA-2 measurements revealed that 2H, 3H, 3He, and 4He are a significant portion of the secondary flux above the atmosphere. The energy spectra of hydrogen isotopes are practically flat across the energy range of 10-40 MeV/n, while the spectra of helium isotopes can be fitted by a power law of spectral indexes γ = 0.8 and γ = 1.5 for 3He and 4He, respectively.

  11. London atmospheric Hydrogen and Carbon Monoxide: 12 year record, fluxes, and diurnal studies.

    NASA Astrophysics Data System (ADS)

    Lanoisellé, M.; Fisher, R. E.; Sriskantharajah, S.; Lowry, D.; Fowler, C. M. R.; Nisbet, E. G.

    2009-04-01

    Atmospheric hydrogen (H2) and carbon monoxide (CO) have been measured at the Royal Holloway site, 30km WSW of London, for 12 years. This site receives air that has passed over London when there are easterly winds and cleaner, background air when the wind comes from the SW. H2 and CO mixing ratios are measured continuously at 30 minute intervals on a Trace Analytical Reduction Gas Detector coupled to a HP5890 GC since September 1996, and on a Peak Performer I (or PP1) since July 2007 at 5 minute intervals. Both instruments use 2 1/8" packed columns in series: a Unibeads 1S and a Molecular Sieve 5A. The PP1 detector (Reduced Compound Photometer) is an updated version of the old RGD2, and both use zero air as the carrier gas. CO is calibrated twice a month against NOAA-CMDL standards (mixing ratios range: 186 to 300 ppb). H2 was uncalibrated until 2006, but is now calibrated monthly against internal standards (range 530 to 750 ppb) measured at MPI-Jena as part of the Eurohydros project. A linearity correction is applied to each instrument, based on the standard measurements. A secondary standard is measured before each sample on the GC-RGD and another one is measured 4 to 6 times in a row twice a day on the PP1. A target gas is measured daily on both instruments since September 2008. The secondary standards and the target gas are dry ambient air in 70L stainless steel tanks filled to a pressure of 8 bars. Comparison of results from the two instruments suggests that for the most part the data are in good agreement, but an interlaboratory round robin comparison exercise for the Eurohydros project showed that the RGD is not linear at low values of CO. This is particularly noticeable for CO levels below 150 ppb. The long-term record of CO at Royal Holloway shows a significant decline since the start of the record: the annual mean CO mixing ratio in 2008 was three times lower than in 1997. Flux calculations, by ratio against 222Rn, CH4 and CO2, suggest CO emissions

  12. Gaseous toroid around Saturn. [Saturnian ring system for atomic hydrogen trapping in Titan atmospheric model

    NASA Technical Reports Server (NTRS)

    Mcdonough, T. R.

    1974-01-01

    The trapping of Titan's escaping atmosphere in the Saturnian system by a toroidal ring is discussed. The radius of the toroid is comparable to Titan's orbit, or about ten times larger than the visible rings. Theoretical atmospheric models are formulated that consider Saturn's gravitational attraction and magnetospheric properties in forming this toroid and in protecting toroid particles from direct ionization by solar wind particles.

  13. Production of hydrogen peroxide in the atmosphere of a Snowball Earth and the origin of oxygenic photosynthesis.

    PubMed

    Liang, Mao-Chang; Hartman, Hyman; Kopp, Robert E; Kirschvink, Joseph L; Yung, Yuk L

    2006-12-12

    During Proterozoic time, Earth experienced two intervals with one or more episodes of low-latitude glaciation, which are probable "Snowball Earth" events. Although the severity of the historical glaciations is debated, theoretical "hard Snowball" conditions are associated with the nearly complete shutdown of the hydrological cycle. We show here that, during such long and severe glacial intervals, a weak hydrological cycle coupled with photochemical reactions involving water vapor would give rise to the sustained production of hydrogen peroxide. The photochemical production of hydrogen peroxide has been proposed previously as the primary mechanism for oxidizing the surface of Mars. During a Snowball, hydrogen peroxide could be stored in the ice; it would then be released directly into the ocean and the atmosphere upon melting and could mediate global oxidation events in the aftermath of the Snowball, such as that recorded in the Fe and Mn oxides of the Kalahari Manganese Field, deposited after the Paleoproterozoic low-latitude Makganyene glaciation. Low levels of peroxides and molecular oxygen generated during Archean and earliest Proterozoic non-Snowball glacial intervals could have driven the evolution of oxygen-mediating and -using enzymes and thereby paved the way for the eventual appearance of oxygenic photosynthesis.

  14. Novel atmospheric pressure plasma device releasing atomic hydrogen: reduction of microbial-contaminants and OH radicals in the air

    NASA Astrophysics Data System (ADS)

    Nojima, Hideo; Park, Rae-Eun; Kwon, Jun-Hyoun; Suh, Inseon; Jeon, Junsang; Ha, Eunju; On, Hyeon-Ki; Kim, Hye-Ryung; Choi, Kyoung Hui; Lee, Kwang-Hee; Seong, Baik-Lin; Jung, Hoon; Kang, Shin Jung; Namba, Shinichi; Takiyama, Ken

    2007-01-01

    A novel atmospheric pressure plasma device releasing atomic hydrogen has been developed. This device has specific properties such as (1) deactivation of airborne microbial-contaminants, (2) neutralization of indoor OH radicals and (3) being harmless to the human body. It consists of a ceramic plate as a positive ion generation electrode and a needle-shaped electrode as an electron emission electrode. Release of atomic hydrogen from the device has been investigated by the spectroscopic method. Optical emission of atomic hydrogen probably due to recombination of positive ions, H+(H2O)n, generated from the ceramic plate electrode and electrons emitted from the needle-shaped electrode have been clearly observed in the He gas (including water vapour) environment. The efficacy of the device to reduce airborne concentrations of influenza virus, bacteria, mould fungi and allergens has been evaluated. 99.6% of airborne influenza virus has been deactivated with the operation of the device compared with the control test in a 1 m3 chamber after 60 min. The neutralization of the OH radical has been investigated by spectroscopic and biological methods. A remarkable reduction of the OH radical in the air by operation of the device has been observed by laser-induced fluorescence spectroscopy. The cell protection effects of the device against OH radicals in the air have been observed. Furthermore, the side effects have been checked by animal experiments. The harmlessness of the device has been confirmed.

  15. Catalytic Fast Pyrolysis of Biomass Impregnated with Potassium Phosphate in a Hydrogen Atmosphere for the Production of Phenol and Activated Carbon.

    PubMed

    Lu, Qiang; Zhang, Zhen-Xi; Wang, Xin; Guo, Hao-Qiang; Cui, Min-Shu; Yang, Yong-Ping

    2018-01-01

    A new technique was proposed to co-produce phenol and activated carbon (AC) from catalytic fast pyrolysis of biomass impregnated with K 3 PO 4 in a hydrogen atmosphere, followed by activation of the pyrolytic solid residues. Lab-scale catalytic fast pyrolysis experiments were performed to quantitatively determine the pyrolytic product distribution, as well as to investigate the effects of several factors on the phenol production, including pyrolysis atmosphere, catalyst type, biomass type, catalytic pyrolysis temperature, and catalyst impregnation content. In addition, the pyrolytic solid residues were activated to prepare ACs with high specific surface areas. The results indicated that phenol could be obtained due to the synergistic effects of K 3 PO 4 and hydrogen atmosphere, with the yield and selectivity reaching 5.3 wt% and 17.8% from catalytic fast pyrolysis of poplar wood with 8 wt% K 3 PO 4 at 550°C in a hydrogen atmosphere. This technique was adaptable to different woody materials for phenol production. Moreover, gas product generated from the pyrolysis process was feasible to be recycled to provide the hydrogen atmosphere, instead of extra hydrogen supply. In addition, the pyrolytic solid residue was suitable for AC preparation, using CO 2 activation method, the specific surface area was as high as 1,605 m 2 /g.

  16. Catalytic Fast Pyrolysis of Biomass Impregnated with Potassium Phosphate in a Hydrogen Atmosphere for the Production of Phenol and Activated Carbon

    PubMed Central

    Lu, Qiang; Zhang, Zhen-xi; Wang, Xin; Guo, Hao-qiang; Cui, Min-shu; Yang, Yong-ping

    2018-01-01

    A new technique was proposed to co-produce phenol and activated carbon (AC) from catalytic fast pyrolysis of biomass impregnated with K3PO4 in a hydrogen atmosphere, followed by activation of the pyrolytic solid residues. Lab-scale catalytic fast pyrolysis experiments were performed to quantitatively determine the pyrolytic product distribution, as well as to investigate the effects of several factors on the phenol production, including pyrolysis atmosphere, catalyst type, biomass type, catalytic pyrolysis temperature, and catalyst impregnation content. In addition, the pyrolytic solid residues were activated to prepare ACs with high specific surface areas. The results indicated that phenol could be obtained due to the synergistic effects of K3PO4 and hydrogen atmosphere, with the yield and selectivity reaching 5.3 wt% and 17.8% from catalytic fast pyrolysis of poplar wood with 8 wt% K3PO4 at 550°C in a hydrogen atmosphere. This technique was adaptable to different woody materials for phenol production. Moreover, gas product generated from the pyrolysis process was feasible to be recycled to provide the hydrogen atmosphere, instead of extra hydrogen supply. In addition, the pyrolytic solid residue was suitable for AC preparation, using CO2 activation method, the specific surface area was as high as 1,605 m2/g. PMID:29515994

  17. Catalytic fast pyrolysis of biomass impregnated with potassium phosphate in a hydrogen atmosphere for the production of phenol and activated carbon

    NASA Astrophysics Data System (ADS)

    Lu, Qiang; Zhang, Zhen-xi; Wang, Xin; Guo, Hao-qiang; Cui, Min-shu; Yang, Yong-ping

    2018-02-01

    A new technique was proposed to co-produce phenol and activated carbon (AC) from catalytic fast pyrolysis of biomass impregnated with K3PO4 in a hydrogen atmosphere, followed by activation of the pyrolytic solid residues. Lab-scale catalytic fast pyrolysis experiments were performed to quantitatively determine the pyrolytic product distribution, as well as to investigate the effects of several factors on the phenol production, including pyrolysis atmosphere, catalyst type, biomass type, catalytic pyrolysis temperature, and catalyst impregnation content. In addition, the pyrolytic solid residues were activated to prepare ACs with high specific surface areas. The results indicated that phenol could be obtained due to the synergistic effects of K3PO4 and hydrogen atmosphere, with the yield and selectivity reaching 5.3 wt% and 17.8% from catalytic fast pyrolysis of poplar wood with 8 wt% K3PO4 at 550 oC in a hydrogen atmosphere. This technique was adaptable to different woody materials for phenol production. Moreover, gas product generated from the pyrolysis process was feasible to be recycled to provide the hydrogen atmosphere, instead of extra hydrogen supply. In addition, the pyrolytic solid residue was suitable for AC preparation, using CO2 activation method, the specific surface area was as high as 1605 m2/g.

  18. The quenching effect of hydrogen on the nitrogen in metastable state in atmospheric-pressure N{sub 2}-H{sub 2} microwave plasma torch

    SciTech Connect

    Li, Shou-Zhe, E-mail: lisz@dlut.edu.cn; Zhang, Xin; Chen, Chuan-Jie

    2014-07-15

    The atmospheric-pressure microwave N{sub 2}-H{sub 2} plasma torch is generated and diagnosed by optical emission spectroscopy. It is found that a large amount of N atoms and NH radicals are generated in the plasma torch and the emission intensity of N{sub 2}{sup +} first negative band is the strongest over the spectra. The mixture of hydrogen in nitrogen plasma torch causes the morphology of the plasma discharge to change with appearance that the afterglow shrinks greatly and the emission intensity of N{sub 2}{sup +} first negative band decreases with more hydrogen mixed into nitrogen plasma. In atmospheric-pressure microwave-induced plasma torch,more » the hydrogen imposes a great influence on the characteristics of nitrogen plasma through the quenching effect of the hydrogen on the metastable state of N{sub 2}.« less

  19. Vapor hydrogen and oxygen isotopes reflect water of combustion in the urban atmosphere

    PubMed Central

    Gorski, Galen; Strong, Courtenay; Good, Stephen P.; Bares, Ryan; Ehleringer, James R.; Bowen, Gabriel J.

    2015-01-01

    Anthropogenic modification of the water cycle involves a diversity of processes, many of which have been studied intensively using models and observations. Effective tools for measuring the contribution and fate of combustion-derived water vapor in the atmosphere are lacking, however, and this flux has received relatively little attention. We provide theoretical estimates and a first set of measurements demonstrating that water of combustion is characterized by a distinctive combination of H and O isotope ratios. We show that during periods of relatively low humidity and/or atmospheric stagnation, this isotopic signature can be used to quantify the concentration of water of combustion in the atmospheric boundary layer over Salt Lake City. Combustion-derived vapor concentrations vary between periods of atmospheric stratification and mixing, both on multiday and diurnal timescales, and respond over periods of hours to variations in surface emissions. Our estimates suggest that up to 13% of the boundary layer vapor during the period of study was derived from combustion sources, and both the temporal pattern and magnitude of this contribution were closely reproduced by an independent atmospheric model forced with a fossil fuel emissions data product. Our findings suggest potential for water vapor isotope ratio measurements to be used in conjunction with other tracers to refine the apportionment of urban emissions, and imply that water vapor emissions associated with combustion may be a significant component of the water budget of the urban boundary layer, with potential implications for urban climate, ecohydrology, and photochemistry. PMID:25733906

  20. Vapor hydrogen and oxygen isotopes reflect water of combustion in the urban atmosphere.

    PubMed

    Gorski, Galen; Strong, Courtenay; Good, Stephen P; Bares, Ryan; Ehleringer, James R; Bowen, Gabriel J

    2015-03-17

    Anthropogenic modification of the water cycle involves a diversity of processes, many of which have been studied intensively using models and observations. Effective tools for measuring the contribution and fate of combustion-derived water vapor in the atmosphere are lacking, however, and this flux has received relatively little attention. We provide theoretical estimates and a first set of measurements demonstrating that water of combustion is characterized by a distinctive combination of H and O isotope ratios. We show that during periods of relatively low humidity and/or atmospheric stagnation, this isotopic signature can be used to quantify the concentration of water of combustion in the atmospheric boundary layer over Salt Lake City. Combustion-derived vapor concentrations vary between periods of atmospheric stratification and mixing, both on multiday and diurnal timescales, and respond over periods of hours to variations in surface emissions. Our estimates suggest that up to 13% of the boundary layer vapor during the period of study was derived from combustion sources, and both the temporal pattern and magnitude of this contribution were closely reproduced by an independent atmospheric model forced with a fossil fuel emissions data product. Our findings suggest potential for water vapor isotope ratio measurements to be used in conjunction with other tracers to refine the apportionment of urban emissions, and imply that water vapor emissions associated with combustion may be a significant component of the water budget of the urban boundary layer, with potential implications for urban climate, ecohydrology, and photochemistry.

  1. Hydrogen Isotopes Record the History of the Martian Hydrosphere and Atmosphere

    NASA Technical Reports Server (NTRS)

    Usui, T.; Simon, J. I.; Jones, J. H.; Kurokawa, H.; Sato, M.; Alexander, C. M. O'D; Wang, J.

    2015-01-01

    The surface geology and geomorphology of Mars indicates that it was once warm enough to maintain a large body of liquid water on its surface, though such a warm environment might have been transient. The transition to the present cold and dry Mars is closely linked to the history of surface water, yet the evolution of surficial water is poorly constrained. This study presents insights from hydrogen isotopes for the origin and evolution of Martian water reservoirs.

  2. Supercritical fluid chromatography coupled with in-source atmospheric pressure ionization hydrogen/deuterium exchange mass spectrometry for compound speciation.

    PubMed

    Cho, Yunju; Choi, Man-Ho; Kim, Byungjoo; Kim, Sunghwan

    2016-04-29

    An experimental setup for the speciation of compounds by hydrogen/deuterium exchange (HDX) with atmospheric pressure ionization while performing chromatographic separation is presented. The proposed experimental setup combines the high performance supercritical fluid chromatography (SFC) system that can be readily used as an inlet for mass spectrometry (MS) and atmospheric pressure photo ionization (APPI) or atmospheric pressure chemical ionization (APCI) HDX. This combination overcomes the limitation of an approach using conventional liquid chromatography (LC) by minimizing the amount of deuterium solvents used for separation. In the SFC separation, supercritical CO2 was used as a major component of the mobile phase, and methanol was used as a minor co-solvent. By using deuterated methanol (CH3OD), AP HDX was achieved during SFC separation. To prove the concept, thirty one nitrogen- and/or oxygen-containing standard compounds were analyzed by SFC-AP HDX MS. The compounds were successfully speciated from the obtained SFC-MS spectra. The exchange ions were observed with as low as 1% of CH3OD in the mobile phase, and separation could be performed within approximately 20min using approximately 0.24 mL of CH3OD. The results showed that SFC separation and APPI/APCI HDX could be successfully performed using the suggested method. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Effects of residual hydrogen in sputtering atmosphere on structures and properties of amorphous In-Ga-Zn-O thin films

    SciTech Connect

    Tang, Haochun; Ishikawa, Kyohei; Ide, Keisuke

    2015-11-28

    We investigated the effects of residual hydrogen in sputtering atmosphere on subgap states and carrier transport in amorphous In-Ga-Zn-O (a-IGZO) using two sputtering systems with different base pressures of ∼10{sup −4} and 10{sup −7 }Pa (standard (STD) and ultrahigh vacuum (UHV) sputtering, respectively), which produce a-IGZO films with impurity hydrogen contents at the orders of 10{sup 20} and 10{sup 19 }cm{sup −3}, respectively. Several subgap states were observed by hard X-ray photoemission spectroscopy, i.e., peak-shape near-valence band maximum (near-VBM) states, shoulder-shape near-VBM states, peak-shape near-conduction band minimum (near-CBM) states, and step-wise near-CBM states. It was confirmed that the formation of these subgapmore » states were affected strongly by the residual hydrogen (possibly H{sub 2}O). The step-wise near-CBM states were observed only in the STD films deposited without O{sub 2} gas flow and attributed to metallic In. Such step-wise near-CBM state was not detected in the other films including the UHV films even deposited without O{sub 2} flow, substantiating that the metallic In is segregated by the strong reduction effect of the hydrogen/H{sub 2}O. Similarly, the density of the near-VBM states was very high for the STD films deposited without O{sub 2}. These films had low film density and are consistent with a model that voids in the amorphous structure form a part of the near-VBM states. On the other hand, the UHV films had high film densities and much less near-VBM states, keeping the possibility that some of the near-VBM states, in particular, of the peak-shape ones, originate from –OH and weakly bonded oxygen. These results indicate that 2% of excess O{sub 2} flow is required for the STD sputtering to compensate the effects of the residual hydrogen/H{sub 2}O. The high-density near-VBM states and the metallic In segregation deteriorated the electron mobility to 0.4 cm{sup 2}/(V s)« less

  4. Vapor hydrogen and oxygen isotopes reflect water of combustion in the urban atmosphere

    DOE PAGES

    Gorski, Galen; Strong, Courtenay; Good, Stephen P.; ...

    2015-03-02

    Anthropogenic modification of the water cycle involves a diversity of processes, many of which have been studied intensively using models and observations. Some effective tools for measuring the contribution and fate of combustion-derived water vapor in the atmosphere are lacking, however, and this flux has received relatively little attention. We provide theoretical estimates and a first set of measurements demonstrating that water of combustion is characterized by a distinctive combination of H and O isotope ratios. Furthermore, we show that during periods of relatively low humidity and/or atmospheric stagnation, this isotopic signature can be used to quantify the concentration ofmore » water of combustion in the atmospheric boundary layer over Salt Lake City. Combustion-derived vapor concentrations vary between periods of atmospheric stratification and mixing, both on multiday and diurnal timescales, and respond over periods of hours to variations in surface emissions. Our estimates suggest that up to 13% of the boundary layer vapor during the period of study was derived from combustion sources, and both the temporal pattern and magnitude of this contribution were closely reproduced by an independent atmospheric model forced with a fossil fuel emissions data product. These findings suggest potential for water vapor isotope ratio measurements to be used in conjunction with other tracers to refine the apportionment of urban emissions, and imply that water vapor emissions associated with combustion may be a significant component of the water budget of the urban boundary layer, with potential implications for urban climate, ecohydrology, and photochemistry.« less

  5. Facile and efficient one-pot synthesis of 2-arylbenzoxazoles using hydrogen tetrachloroaurate as catalyst under oxygen atmosphere*

    PubMed Central

    Liu, Yun-kui; Mao, Da-jie; Lou, Shao-jie; Qian, Jian-qiang; Xu, Zhen-yuan

    2009-01-01

    In this paper, we presented a novel method for the facile and efficient one-pot synthesis of 2-arylbenzoxazoles, which were directly synthesized from 2-aminophenol and aldehydes catalyzed by hydrogen tetrachloroaurate (HAuCl4·4H2O) under an oxygen atmosphere with anhydrous tetrahydrofuran (THF) as solvent or in solvent-free condition. The results show that this method could bring excellent yields as high as 96%. THF was proven to be the best choice among several solvents screened and the reaction was tolerated with a variety of aromatic aldehydes possessing electron-donating or withdrawing groups. The advantages of the present method lie in catalytic process using economic and environmentally benign dioxygen as oxidant. PMID:19489113

  6. Atmospheric implication of the hydrogen bonding interaction in hydrated clusters of HONO and dimethylamine in the nighttime.

    PubMed

    Zhao, Hailiang; Du, Lin

    2017-01-25

    In this study, the stability of clusters formed by the trans- and cis-isomers of nitrous acid (HONO) with dimethylamine (DMA) and water has been characterized by density functional theory. The large red shifts of the OH-stretching transitions of both HONO isomers in the clusters indicate the formation of strong hydrogen bonds. At standard temperature and pressure, H 2 O (acceptor) binds to HONO (donor) with binding energies of -25.0 to -24.6 kJ mol -1 , less stable than those of DMA (acceptor) with HONO (donor) (-50.5 to -45.3 kJ mol -1 ). Our findings indicate that hydration enhances proton transfer from HONO to DMA, and consequently increases the interaction strength (binding energies = -67.8 to -78.6 kJ mol -1 ). The topological and generalized Kohn-Sham energy decomposition confirms strong hydrogen bond interactions. The clustering of HONO with DMA in the atmosphere is negligible as compared to the important H 2 SO 4 -DMA clusters.

  7. Electromagnetic optimisation of a 2.45 GHz microwave plasma source operated at atmospheric pressure and designed for hydrogen production

    NASA Astrophysics Data System (ADS)

    Miotk, R.; Jasiński, M.; Mizeraczyk, J.

    2018-03-01

    This paper presents the partial electromagnetic optimisation of a 2.45 GHz cylindrical-type microwave plasma source (MPS) operated at atmospheric pressure. The presented device is designed for hydrogen production from liquid fuels, e.g. hydrocarbons and alcohols. Due to industrial requirements regarding low costs for hydrogen produced in this way, previous testing indicated that improvements were required to the electromagnetic performance of the MPS. The MPS has a duct discontinuity region, which is a result of the cylindrical structure located within the device. The microwave plasma is generated in this discontinuity region. Rigorous analysis of the region requires solving a set of Maxwell equations, which is burdensome for complicated structures. Furthermore, the presence of the microwave plasma increases the complexity of this task. To avoid calculating the complex Maxwell equations, we suggest the use of the equivalent circuit method. This work is based upon the idea of using a Weissfloch circuit to characterize the area of the duct discontinuity and the plasma. The resulting MPS equivalent circuit allowed the calculation of a capacitive metallic diaphragm, through which an improvement in the electromagnetic performance of the plasma source was obtained.

  8. Methane conversion using a dielectric barrier discharge reactor at atmospheric pressure for hydrogen production

    NASA Astrophysics Data System (ADS)

    Khadir, N.; Khodja, K.; Belasri, A.

    2017-09-01

    In the present paper, we carried out a theoretical study of dielectric barrier discharge (DBD) filled with pure methane gas. The homogeneous discharge model used in this work includes a plasma chemistry unit, an electrical circuit, and the Boltzmann equation. The model was applied to the case of a sinusoidal voltage at a period frequency of 50 kHz and under a gas pressure of 600 Torr. We investigated the temporal variation of electrical and kinetic discharge parameters such as plasma and dielectric voltages, the discharge current density, electric field, deposited power density, and the species concentration. We also checked the physical model validity by comparing its results with experimental work. According to the results discussed herein, the dielectric capacitance is the parameter that has the greatest effect on the methane conversion and H2/CH4 ratio. This work enriches the knowledge for the improvement of DBD for CH4 conversion and hydrogen production.

  9. High-resolution Measurements of Gas-Phase Hydrogen Chloride (HCl) in the Atmosphere by Cavity Ring Down Spectroscopy

    NASA Astrophysics Data System (ADS)

    Hoffnagle, John; Chen, Hongbing; Lee, Jim; Rella, Chris; Kim-Hak, David; Winkler, Renato; Markovic, Milos; Veres, Patrick

    2017-04-01

    Halogen radical species, such as chlorine and bromine atoms and their oxides, can greatly affect the chemical composition of the troposphere. Hydrogen chloride is the dominant (gas-phase) contributor to the tropospheric chlorine inventory. Real time in situ observations of HCl can provide an important window into the complex photochemical reaction pathways for chlorine in the atmosphere, including heterogeneous reactions on aerosol surfaces. In this work, we report a novel, commercially-available HCl gas-phase analyzer (G2108, Picarro Inc. Santa Clara, CA, USA) based upon Cavity Ring Down Spectroscopy (CRDS) in the near-infrared, and discuss its performance. With a measurement interval of approximately 2 seconds, a precision of better than 40 parts-per-trillion (1 sigma, 30 seconds), and a response time of approximately 1-2 minutes (10 - 90% rise time or 90 - 10% fall time), this analyzer is well-suited for measurements of atmospherically-relevant concentrations of HCl, in both laboratory and field. CRDS provides very stable measurements and low drift, requiring infrequent calibration of the instrument, and can therefore be operated remotely for extended periods of time. In this work we also present results from a laboratory intercomparison of the Picarro G2108 analyzer and an iodide ion time-of-flight Chemical Ionization Mass Spectrometer (CIMS), and the results of the analyzer time response tests.

  10. Micro gas analysis system for measurement of atmospheric hydrogen sulfide and sulfur dioxide.

    PubMed

    Ohira, Shin-Ichi; Toda, Kei

    2005-12-01

    A honeycomb structure microchannel scrubber was developed to achieve efficient and stable gas collection. A thin porous membrane was pasted on a microchannel by the adhesive force of a fresh polydimethylsiloxane surface. The microchannel scrubber achieved much more efficient gas collection than conventional impingers and diffusion scrubbers. Two sets of the microchannel scrubbers and detectors were integrated in a 10 cm x 9 cm plastic board to create a micro gas analysis system (microGAS) for simultaneous measurements of H2S and SO2. The whole system including a battery was incorporated in a carrying case 34 cm W x 16 cm D x 17 cm H for use in the field. Liquid flows at 30 microl min(-1) were obtained by bimetal micropumps. The estimated detection limits were 0.1 ppbv for H2S and 1 ppbv for SO2. The system was demonstrated for real atmospheric gas analysis, and the results agreed well with data concurrently obtained by ion chromatography coupled with a cylindrical diffusion scrubber. The system we developed allowed automated continuous analyses in the field and achieved a much higher time resolution compared to those by ion chromatographic analysis.

  11. Inelastic silicon-hydrogen collision data for non-LTE applications in stellar atmospheres

    NASA Astrophysics Data System (ADS)

    Belyaev, Andrey K.; Yakovleva, Svetlana A.; Barklem, Paul S.

    2014-12-01

    Aims: Inelastic processes in low-energy Si + H and Si+ + H- collisions are treated for the states from the ground state up to the ionic state, in order to provide rate coefficients needed for non-LTE modeling of Si in cool stellar atmospheres. Methods: Electronic molecular structure is determined using a recently proposed model approach based on an asymptotic method in combination with available ab initio potentials. Nonadiabatic nuclear dynamics are treated by means of a combination of multichannel formulas and the branching-probability-current method, based on the Landau-Zener model for nonadiabatic transition probabilities. Results: Cross sections and rate coefficients for inelastic processes in Si + H and Si+ + H- collisions for all transitions between 26 low-lying states plus the ionic state are calculated. It is shown that the highest rate coefficient values correspond to the excitation, de-excitation, ion-pair formation, and mutual neutralization processes involving the Si(3p4p 3D), Si(3p3d 3F), Si(3p4p 1D), Si(3p3d 3P), Si(3p4p 1S), and the ionic Si+ + H- states. These processes are likely to be important in non-LTE modeling. Tables 2-11 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/572/A103

  12. Model estimates of inelastic calcium-hydrogen collision data for non-LTE stellar atmospheres modeling

    NASA Astrophysics Data System (ADS)

    Belyaev, A. K.; Yakovleva, S. A.; Guitou, M.; Mitrushchenkov, A. O.; Spielfiedel, A.; Feautrier, N.

    2016-03-01

    Aims: Inelastic processes in low-energy Ca + H and Ca+ + H- collisions are treated for the states from the ground state up to the ionic state with the aim to provide rate coefficients needed for non-LTE modeling of Ca in cool stellar atmospheres. Methods: The electronic molecular structure was determined using a recently proposed model approach that is based on an asymptotic method. Nonadiabatic nuclear dynamics were treated by means of multichannel formulas, based on the Landau-Zener model for nonadiabatic transition probabilities. Results: The cross sections and rate coefficients for inelastic processes in Ca + H and Ca+ + H- collisions were calculated for all transitions between 17 low-lying covalent states plus the ionic state. It is shown that the highest rate coefficient values correspond to the excitation, de-excitation, ion-pair formation, and mutual neutralization processes involving the Ca(4s5s 1,3S) and the ionic Ca+ + H- states. The next group with the second highest rate coefficients includes the processes involving the Ca(4s5p 1,3P), Ca(4s4d 1,3D), and Ca(4s4p 1P) states. The processes from these two groups are likely to be important for non-LTE modeling. Tables 2-11 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/587/A114

  13. Surface kinetics for catalytic combustion of hydrogen-air mixtures on platinum at atmospheric pressure in stagnation flows

    NASA Astrophysics Data System (ADS)

    Ikeda, H.; Sato, J.; Williams, F. A.

    1995-03-01

    Experimental studies of the combustion of premixed hydrogen-air mixtures impinging on the surface of a heated platinum plate at normal atmospheric pressure were performed and employed to draw inferences concerning surface reaction mechanisms and rate parameters applicable under practical conditions of catalytic combustion. Plate and gas temperatures were measured by thermocouples, and concentration profiles of major stable species in the gas were measured by gas-chromatographic analyses of samples withdrawn by quartz probes. In addition, ignition and extinction phenomena were recorded and interpreted with the aid of a heat balance at the surface and a previous flow-field analysis of the stagnation-point boundary layer. From the experimental and theoretical results, conclusions were drawn concerning the surface chemical-kinetic mechanisms and values of the elementary rate parameters that are consistent with the observations. In particular, the activation energy for the surface oxidation step H + OH → H 2O is found to be appreciably less at these high surface coverages than in the low-coverage limit.

  14. Diamondoid synthesis in atmospheric pressure adamantane-argon-methane-hydrogen mixtures using a continuous flow plasma microreactor

    NASA Astrophysics Data System (ADS)

    Stauss, Sven; Ishii, Chikako; Pai, David Z.; Urabe, Keiichiro; Terashima, Kazuo

    2014-06-01

    Due to their small size, low-power consumption and potential for integration with other devices, microplasmas have been used increasingly for the synthesis of nanomaterials. Here, we have investigated the possibility of using dielectric barrier discharges generated in continuous flow glass microreactors for the synthesis of diamondoids, at temperatures of 300 and 320 K, and applied voltages of 3.2-4.3 kVp-p, at a frequency of 10 kHz. The microplasmas were generated in gas mixtures containing argon, methane, hydrogen and adamantane, which was used as a precursor and seed. The plasmas were monitored by optical emission spectroscopy measurements and the synthesized products were characterized by gas chromatography—mass spectrometry (GC-MS). Depending on the gas composition, the optical emission spectra contained CH and C2 bands of varying intensities. The GC-MS measurements revealed that diamantane can be synthesized by microplasmas generated at atmospheric pressure, and that the yields highly depend on the gas composition and the presence of carbon sources.

  15. Method for the determination of lignin content of a sample by flash pyrolysis in an atmosphere of hydrogen or helium and method therefor

    NASA Technical Reports Server (NTRS)

    Shakkottai, Parthasarathy (Inventor); Kwack, Eug Y. (Inventor); Lawson, Daniel D. (Inventor)

    1991-01-01

    The lignin content of wood, paper pulp or other material containing lignin (such as filter paper soaked in black liquor) is more readily determined by flash pyrolysis of the sample at approximately 550.degree. C. in a reducing atmosphere of hydrogen or in an inert atmosphere of helium followed by a rapid analysis of the product gas by a mass spectrometer. The heated pyrolysis unit as fabricated comprises a small platinum cup welded to an electrically-heated stainless steel ribbon with control means for programmed short duration (1.5 sec, approximately) heating and means for continuous flow of hydrogen or helium. The pyrolysis products enter an electron-ionization mode mass spectrometer for spectral evaluation. Lignin content is obtained from certain ratios of integrated ion currents of many mass spectral lines, the ratios being linearly related to the Kappa number of Klason lignin.

  16. Features of the propagation of laminar spherical flames initiated by a spark discharge in mixtures of methane, pentane, and hydrogen with air at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Rubtsov, N. M.; Seplyarskii, B. S.; Troshin, K. Ya.; Chernysh, V. I.; Tsvetkov, G. I.

    2011-10-01

    Using high-speed digital color cinematography, we studied the propagation of a laminar spherical flame in stoichiometric mixtures of hydrogen, methane, and pentane with air in the presence of additives at atmospheric pressure in constant-volume reactors, and derived quantitative data on the time of formation of a stable flame front. Cellular flames caused by gas-dynamic instability attributable to convective flows arising during the afterburning of gas were observed in hydrocarbon-air stoichiometric mixtures diluted with inert additives. It was found that the effect of additives of carbon dioxide and argon (>10%) and minor additives of CCl4 on the combustion of hydrocarbons, and of propylene on the combustion of hydrogen-rich mixtures, lead to periods of delay in the development of a laminar spherical flame; in addition, additives of propylene promote the combustion of hydrogen poor mixtures.

  17. What Would It Take for an Atmospheric Neutrino Detector to Constrain the Hydrogen Content of the Earth's Core ?

    NASA Astrophysics Data System (ADS)

    Bourret, S.; Coelho, J. A. B.; Kaminski, E. C.; Van Elewyck, V.

    2017-12-01

    The difference between PREM density and seismic profiles in the Earth's core and the values for pure iron and iron-nickel alloys inferred from high pressure/high temperature experiments and ab initio calculations requires the presence of a few wt% of light elements. The nature and amount of these light elements (O, Si, S, H, C...) remains controversial. Recent studies have renewed the interest in H. It is the most abundant element in the nebula and can be easily dissolved in iron in the early stages of Earth's evolution. 1 to 2 wt% of H could explain the difference between PREM and pure iron. However, current geophysical methods alone cannot settle the debate between H and the other candidate elements. Neutrino oscillation tomography using atmospheric neutrinos opens an avenue to collect independent data on Earth's core composition. This method exploits the quantum phenomenon of neutrino flavour oscillations, which depends on the electron density along the path of the neutrino through the Earth. The combination of a neutrino-based measurement of the electron density with the PREM mass density profile constrains the average proton-to-nucleon ratio of the medium (Z/A). Since this parameter varies among chemical elements, e.g. 0.466 for Fe and 1 for H, this technique has the potential to provide unprecedented insights into the chemical composition of the core, and in particular its hydrogen content. Performing such a measurement requires large-size detectors with good efficiency in the relevant energy range and precise determination of the neutrino energy, arrival direction, and flavour. Considering a generic but realistic model of detector response, we quantify the influence of various detector performance indicators on the sensitivity to the average Z/A in the core. We further evaluate the impact of systematic uncertainties, such as those related to the physical model for neutrino oscillations and the incoming flux of atmospheric neutrinos. We consider specific

  18. Hydroxyalkoxy radicals: importance of intramolecular hydrogen bonding on chain branching reactions in the combustion and atmospheric decomposition of hydrocarbons.

    PubMed

    Davis, Alexander C; Francisco, Joseph S

    2014-11-20

    During both the atmospheric oxidation and combustion of volatile organic compounds, sequential addition of oxygen can lead to compounds that contain multiple hydrogen-bonding sites. The presence of two or more of these sites on a hydrocarbon introduces the possibility of intramolecular H-bonding, which can have a stabilizing effect on the reactants, products, and transition states of subsequent reactions. The present work compares the absolute energies of two sets of conformations, those that contain intramolecular H-bonds and those that lack intramolecular H-bonds, for each reactant, product, and transition state species in the 1,2 through 1,7 H-migrations and Cα-Cβ, Cα-H, and Cα-OH-bond scission reactions in the n-hydroxyeth-1-oxy through n-hydroxyhex-1-oxy radicals, for n ranging from 1 to 6. The difference in energy between the two conformations represents the balance between the stabilizing effects of H-bonds and the steric cost of bringing the two H-bonding sites together. The effect of intramolecular H-bonding and the OH group is assessed by comparing the net intramolecular H-bond stabilization energies, the reaction enthalpies, and barrier heights of the n-hydroxyalkoxy radical reactions with the corresponding alkoxy radicals values. The results suggest that there is a complex dependence on the location of the two H-bonding groups, the location of the abstraction or bond scission, and the shape of the transition state that dictates the extent to which intramolecular H-bonding effects the relative importance of H-migration and bond scission reactions for each n-hydroxyalkoxy radical. These findings have important implications for future studies on hydrocarbons with multiple H-bonding sites.

  19. Proprietes des melanges de poudres d'aciers inoxydables 316L/h-BN et 409L/h-BN frittes sous differentes atmospheres (hydrogen-nitrogen)

    NASA Astrophysics Data System (ADS)

    Mercier, Thierry

    L'influence de la composition d'atmospheres de frittage "hydrogene---azote" sur les proprietes de specimens produits par metallurgie des poudres a partir de melanges de poudres d'aciers inoxydables 316L et 409L et de poudre de nitrure de bore hexagonal (h-BN) a ete etudiee. Ces proprietes ont ete comparees a celles de specimens sans h-BN frittes simultanement dans la meme atmosphere. Une mince couche dense s'est formee a la surface des echantillons contenant du h-BN frittes dans une atmosphere contenant au moins 50% en volume d'hydrogene. Cette couche dense ameliore generalement les proprietes de l'alliage 316L. Les proprietes de l'alliage 409L montrent une amelioration beaucoup moins significative qui s'amenuise lorsque l'atmosphere s'appauvrit en azote. L'azote favorise la corrosion de specimens de 409L avec ou sans h-BN. Quant au 316L, il demeure resistant a la corrosion malgre la presence d'un peu d'azote au frittage et l'addition de h-BN lui est benefique particulierement lorsque fritte en presence d'une teneur elevee d'azote (jusqu'a 50%vol. N2) qui permet tout de meme la formation d'une couche dense en surface.

  20. Quantitative depth profiling of Ce(3+) in Pt/CeO2 by in situ high-energy XPS in a hydrogen atmosphere.

    PubMed

    Kato, Shunsuke; Ammann, Markus; Huthwelker, Thomas; Paun, Cristina; Lampimäki, Markus; Lee, Ming-Tao; Rothensteiner, Matthäus; van Bokhoven, Jeroen A

    2015-02-21

    The redox property of ceria is a key factor in the catalytic activity of ceria-based catalysts. The oxidation state of well-defined ceria nanocubes in gas environments was analysed in situ by a novel combination of near-ambient pressure X-ray Photoelectron Spectroscopy (XPS) and high-energy XPS at a synchrotron X-ray source. In situ high-energy XPS is a promising new tool to determine the electronic structure of matter under defined conditions. The aim was to quantitatively determine the degree of cerium reduction in a nano-structured ceria-supported platinum catalyst as a function of the gas environment. To obtain a non-destructive depth profile at near-ambient pressure, in situ high-energy XPS analysis was performed by varying the kinetic energy of photoelectrons from 1 to 5 keV, and, thus, the probing depth. In ceria nanocubes doped with platinum, oxygen vacancies formed only in the uppermost layers of ceria in an atmosphere of 1 mbar hydrogen and 403 K. For pristine ceria nanocubes, no change in the cerium oxidation state in various hydrogen or oxygen atmospheres was observed as a function of probing depth. In the absence of platinum, hydrogen does not dissociate and, thus, does not lead to reduction of ceria.

  1. Analyses of hydrogen in quartz and in sapphire using depth profiling by ERDA at atmospheric pressure: Comparison with resonant NRA and SIMS

    NASA Astrophysics Data System (ADS)

    Reiche, Ina; Castaing, Jacques; Calligaro, Thomas; Salomon, Joseph; Aucouturier, Marc; Reinholz, Uwe; Weise, Hans-Peter

    2006-08-01

    Hydrogen is present in anhydrous materials as a result of their synthesis and of their environment during conservation. IBA provides techniques to measure H concentration depth profiles allowing to identify various aspects of the materials including the history of objects such as gemstones used in cultural heritage. A newly established ERDA set-up, using an external microbeam of alpha particles, has been developed to study hydrated near-surface layers in quartz and sapphire by non-destructive H depth profiling in different atmospheres. The samples were also analysed using resonant NRA and SIMS.

  2. TWO REGIMES OF INTERACTION OF A HOT JUPITER’S ESCAPING ATMOSPHERE WITH THE STELLAR WIND AND GENERATION OF ENERGIZED ATOMIC HYDROGEN CORONA

    SciTech Connect

    Shaikhislamov, I. F.; Prokopov, P. A.; Berezutsky, A. G.

    2016-12-01

    The interaction of escaping the upper atmosphere of a hydrogen-rich non-magnetized analog of HD 209458b with a stellar wind (SW) of its host G-type star at different orbital distances is simulated with a 2D axisymmetric multi-fluid hydrodynamic (HD) model. A realistic Sun-like spectrum of X-ray and ultraviolet radiation, which ionizes and heats the planetary atmosphere, together with hydrogen photochemistry, as well as stellar-planetary tidal interaction are taken into account to generate self-consistently an atmospheric HD outflow. Two different regimes of the planetary and SW interaction have been modeled. These are: (1) the “ captured by the star ” regime, whenmore » the tidal force and pressure gradient drive the planetary material beyond the Roche lobe toward the star, and (2) the “ blown by the wind ” regime, when sufficiently strong SW confines the escaping planetary atmosphere and channels it into the tail. The model simulates in detail the HD interaction between the planetary atoms, protons and the SW, as well as the production of energetic neutral atoms (ENAs) around the planet due to charge exchange between planetary atoms and stellar protons. The revealed location and shape of the ENA cloud, either as a paraboloid shell between the ionopause and bowshock (for the “ blown by the wind ” regime), or a turbulent layer at the contact boundary between the planetary stream and SW (for the “ captured by the star ” regime) are of importance for the interpretation of Ly α absorption features in exoplanetary transit spectra and characterization of the plasma environments.« less

  3. Formation Mechanism of Atmospheric Ammonium Bisulfate: Hydrogen-Bond-Promoted Nearly Barrierless Reactions of SO3 with NH3 and H2 O.

    PubMed

    Chen, Shunwei; Zhao, Yanling; Zhang, Ruiqin

    2018-02-20

    Particulate matter (PM) air pollution threatens the health of people and ecosystems worldwide. As the key component of PM, ammonium sulfate plays a critical role in the formation of aerosol particles; thus, there is an urgent need to know the detailed mechanisms for its formation in the atmosphere. Through a quantum chemistry study, we reveal a series of nearly barrierless reactions that may occur in clusters/droplets in the atmosphere leading to the formation of ammonium bisulfate (NH 4 HSO 4 ), the precursor of ammonium sulfate. In this mechanism, NH 4 HSO 4 is directly formed through one-step reactions of SO 3 with H 2 O and NH 3 promoted by surrounding molecule(s) that substantially lower the reaction activation barrier to ≈0 kcal mol -1 . The promoters of these reactions are found to be various common atmospheric molecules, such as water, ammonia, and sulfuric acid, which can form relatively strong hydrogen bonds with the reaction center. Our results suggest many more similar pathways that can be facilitated by other ambient molecules. Due to its one-step and barrierless reaction characteristics and the great abundance of potential reactions, this mechanism has great implications on the formation of atmospheric ammonium sulfate as well as on the growth of aerosol particles. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. BICUVOX.1-matrix composite electrolyte with yttria-stabilized zirconia as an inert phase: SEM evaluation of the chemical stability under hydrogen atmosphere.

    PubMed

    Piva, R H; Piva, D H; Venturini, J; Floriano, R; Morelli, M R

    2015-01-01

    The purpose of this study is to evaluate the efficacy of yttria-stabilized zirconia (3Y-TZP) as an inert phase to prevent the decomposition of Bi2 V0.9 Cu0.1 O5.5 -δ (BICUVOX.1) electrolyte under reducing atmosphere. A post-mortem scanning electron microscopy (SEM) study was performed after chemical stability tests under hydrogen-rich atmosphere using a Sieverts-type apparatus. SEM results showed that BICUVOX.1 decomposition starts under a hydrogen pressure of 19.7 atm at 300°C, even in the case of the composite containing 3Y-TZP. The microstructure of BICUVOX.1 after decomposition was observed to be composed of microspheres ranging from 10 to 100 µm formed primarily of metallic bismuth. In the composite, in addition to microspheres, the microstructure contained bismuth fibers growth from the grain area of the BICUVOX.1 matrix. Despite significant surface morphological modifications, the grain-boundary-arranged 3Y-TZP particles in a BICUVOX.1-matrix composite did not result in enhanced chemical stability. © Wiley Periodicals, Inc.

  5. Variations in stable hydrogen and oxygen isotopes in atmospheric water vapor in the marine boundary layer across a wide latitude range.

    PubMed

    Liu, Jingfeng; Xiao, Cunde; Ding, Minghu; Ren, Jiawen

    2014-11-01

    The newly-developed cavity ring-down laser absorption spectroscopy analyzer with special calibration protocols has enabled the direct measurement of atmospheric vapor isotopes at high spatial and temporal resolution. This paper presents real-time hydrogen and oxygen stable isotope data for atmospheric water vapor above the sea surface, over a wide range of latitudes spanning from 38°N to 69°S. Our results showed relatively higher values of δ(18)O and δ(2)H in the subtropical regions than those in the tropical and high latitude regions, and also a notable decreasing trend in the Antarctic coastal region. By combining the hydrogen and oxygen isotope data with meteoric water line and backward trajectory model analysis, we explored the kinetic fractionation caused by subsiding air masses and related saturated vapor pressure in the subtropics, and the evaporation-driven kinetic fractionation in the Antarctic region. Simultaneous observations of meteorological and marine variables were used to interpret the isotopic composition characteristics and influential factors, indicating that d-excess is negatively correlated with humidity across a wide range of latitudes and weather conditions worldwide. Coincident with previous studies, d-excess is also positively correlated with sea surface temperature and air temperature (Tair), with greater sensitivity to Tair. Thus, atmospheric vapor isotopes measured with high accuracy and good spatial-temporal resolution could act as informative tracers for exploring the water cycle at different regional scales. Such monitoring efforts should be undertaken over a longer time period and in different regions of the world. Copyright © 2014. Published by Elsevier B.V.

  6. Condensation-inhibited convection in hydrogen-rich atmospheres . Stability against double-diffusive processes and thermal profiles for Jupiter, Saturn, Uranus, and Neptune

    NASA Astrophysics Data System (ADS)

    Leconte, Jérémy; Selsis, Franck; Hersant, Franck; Guillot, Tristan

    2017-02-01

    In an atmosphere, a cloud condensation region is characterized by a strong vertical gradient in the abundance of the related condensing species. On Earth, the ensuing gradient of mean molecular weight has relatively few dynamical consequences because N2 is heavier than water vapor, so that only the release of latent heat significantly impacts convection. On the contrary, in a hydrogen dominated atmosphere (e.g., giant planets), all condensing species are significantly heavier than the background gas. This can stabilize the atmosphere against convection near a cloud deck if the enrichment in the given species exceeds a critical threshold. This raises two questions. What is transporting energy in such a stabilized layer, and how affected can the thermal profile of giant planets be? To answer these questions, we first carry out a linear analysis of the convective and double-diffusive instabilities in a condensable medium showing that an efficient condensation can suppress double-diffusive convection. This suggests that a stable radiative layer can form near a cloud condensation level, leading to an increase in the temperature of the deep adiabat. Then, we investigate the impact of the condensation of the most abundant species (water) with a steady-state atmosphere model. Compared to standard models, the temperature increase can reach several hundred degrees at the quenching depth of key chemical tracers. Overall, this effect could have many implications for our understanding of the dynamical and chemical state of the atmosphere of giant planets, for their future observations (with Juno for example), and for their internal evolution.

  7. The Jovian Atmospheres

    NASA Technical Reports Server (NTRS)

    Allison, Michael (Editor); Travis, Larry D. (Editor)

    1986-01-01

    A conference on the atmosphere of Jupiter produced papers in the areas of thermal and ortho-para hydrogen structure, clouds and chemistry, atmospheric structure, global dynamics, synoptic features and processes, atmospheric dynamics, and future spaceflight opportunities. A session on the atmospheres of Uranus and Neptune was included, and the atmosphere of Saturn was discussed in several papers.

  8. Atmospheric hydrogen peroxide: Evidence for aqueous-phase formation from a historic perspective and a one-year measurement campaign

    NASA Astrophysics Data System (ADS)

    Möller, Detlev

    2009-12-01

    H 2O 2 is produced in the atmospheric gas phase only through a single pathway, the HO 2 radical recombination. Its main role has been identified in oxidizing SO 2 dissolved in hydrometeors to sulphate. Thus aqueous-phase chemistry has been considered to be a main sink (apart from dry deposition and scavenging) but rarely a source of H 2O 2 despite early findings of its heterogeneous and aqueous-phase production. The aim of this paper is to discuss the atmospheric budget of H 2O 2 from the multiphase chemistry approach with special emphasis on new sources other than gas-phase HO 2 recombination. After providing a brief historic view on H 2O 2 chemistry, often unknown to young atmospheric chemists but important for a complete understanding, the results of a one-year study of simultaneous measurements of H 2O 2 in rain and air are presented that show strong evidence for aqueous-phase H 2O 2 formation. Implications for future changes in atmospheric chemistry are discussed from the viewpoint of an "interfacial chemistry".

  9. The reaction of atomic hydrogen with germane - Temperature dependence of the rate constant and implications for germane photochemistry in the atmospheres of Jupiter and Saturn

    NASA Technical Reports Server (NTRS)

    Nava, David F.; Payne, Walter A.; Marston, George; Stief, Louis J.

    1993-01-01

    Studies of the formation and loss processes for GeH4 are required in order to provide data to help determine the major chemical form in which germanium exists in the atmospheres of Jupiter and Saturn. The reaction of hydrogen atoms with germane is one of the most important of these reactions. The absolute rate constant for this reaction as a function of temperature and pressure is studied. Flash photolysis of dilute mixtures of GeH4 in argon, combined with time-resolved detection of H atoms via Lyman alpha resonance fluorescence, is employed to measure the reaction rate. The reaction is shown to be moderately rapid, independent of total pressure, but possessing a positive temperature dependence.

  10. Interaction of hydrogen chloride with alumina. [atmospheric effluent concentrations and interaction of solid rocket propellants used in space shuttle

    NASA Technical Reports Server (NTRS)

    Bailey, R. R.; Wightman, J. P.

    1978-01-01

    The influence of temperature, pressure, and outgas conditions on the absorption of hydrogen chloride and water vapor on both alpha and gamma alumina was studied. Characterization of the adsorbents was performed using X-ray powder diffraction, scanning electron microscopy (SEM), low temperature nitrogen adsorption desorption measurements, BET nitrogen surface area measurements and electron spectroscopy for chemical analysis (ESCA). Water vapor adsorption isotherms at 30, 40, and 50 C were measured on alpha and gamma alumina after outgassing at 80, 200, and 400 C. Both outgas temperature and adsorption temperature influenced the adsorption of water vapor on the aluminas. The water vapor adsorption was completely reversible. Alpha alumina absorbed more water per unit area than gamma alumina. Differences in the adsorption capacity for water vapor of the two aluminas were explained on the basis of ideal surface models of alpha and gamma alumina. Isosteric heats of adsorption for water vapor on the aluminas were determined over a limited range of surface coverage.

  11. Optimization and application of atmospheric pressure chemical and photoionization hydrogen-deuterium exchange mass spectrometry for speciation of oxygen-containing compounds.

    PubMed

    Acter, Thamina; Kim, Donghwi; Ahmed, Arif; Jin, Jang Mi; Yim, Un Hyuk; Shim, Won Joon; Kim, Young Hwan; Kim, Sunghwan

    2016-05-01

    This paper presents a detailed investigation of the feasibility of optimized positive and negative atmospheric pressure chemical ionization (APCI) mass spectrometry (MS) and atmospheric pressure photoionization (APPI) MS coupled to hydrogen-deuterium exchange (HDX) for structural assignment of diverse oxygen-containing compounds. The important parameters for optimization of HDX MS were characterized. The optimized techniques employed in the positive and negative modes showed satisfactory HDX product ions for the model compounds when dichloromethane and toluene were employed as a co-solvent in APCI- and APPI-HDX, respectively. The evaluation of the mass spectra obtained from 38 oxygen-containing compounds demonstrated that the extent of the HDX of the ions was structure-dependent. The combination of information provided by different ionization techniques could be used for better speciation of oxygen-containing compounds. For example, (+) APPI-HDX is sensitive to compounds with alcohol, ketone, or aldehyde substituents, while (-) APPI-HDX is sensitive to compounds with carboxylic functional groups. In addition, the compounds with alcohol can be distinguished from other compounds by the presence of exchanged peaks. The combined information was applied to study chemical compositions of degraded oils. The HDX pattern, double bond equivalent (DBE) distribution, and previously reported oxidation products were combined to predict structures of the compounds produced from oxidation of oil. Overall, this study shows that APCI- and APPI-HDX MS are useful experimental techniques that can be applied for the structural analysis of oxygen-containing compounds.

  12. Oxidation-reduction processes upon interaction of aluminum oxide melt with molybdenum and tungsten in a hydrogen-containing atmosphere

    NASA Astrophysics Data System (ADS)

    Kostomarov, D. V.

    2017-07-01

    A thermodynamic analysis of the processes occurring in the Mo-W-Al2O3 system at T = 2400 K and a total pressure of 1 bar, set by controlled reducing Ar + H2 atmosphere, has been performed. It is found that the basic components of the system do not interact directly, although may be actively involved in chemical reactions with participation of other components to undergo numerous cyclic oxidation-reduction processes. Particular attention is paid to the processes involving such chemically active reagents as H2O2, HO2, H2 (H), gaseous Al, and its hydrides (AlH, AlH2, AlH3).

  13. The continuous measurement of hydrogen chloride in the ambient atmosphere using the dual isotope infrared absorption technique

    NASA Technical Reports Server (NTRS)

    Williams, K. G.

    1974-01-01

    The results of a program to develop a prototype gas filter correlation NDIR analyzer capable of providing the required HCl measurement capability, while maintaining an adequate rejection of any other gases anticipated in the atmosphere are presented. Examples of the performance of the prototype analyzer are presented which show an rms noise equivalent concentration of 0.06 ppm of HCl was achieved while maintaining an electronically determined 10% to 90% time response to gas samples of about 2 seconds. No measureable response was observed to CO2, CO, and H2O while maintaining an adequate rejection of the hydrocarbons, for example CH4 and n-hexane. The experiments were performed which demonstrate that the span stability of the HCl gas filter correlation analyzer is unaffected by the presence of water vapor and which support the belief that the incorporation of a relatively open-volume, multiple path sample cell into the instrument would enable ground station as well as airborne measurements of trace quantities of HCl in the ambient atmosphere to be performed.

  14. Continuous-flow isotope ratio mass spectrometry method for carbon and hydrogen isotope measurements on atmospheric methane

    NASA Astrophysics Data System (ADS)

    Brass, M.; Röckmann, T.

    2010-12-01

    We describe a continuous-flow isotope ratio mass spectrometry (CF-IRMS) technique for high-precision δD and δ13C measurements of atmospheric methane on 40 mL air samples. CH4 is separated from other air components by utilizing purely physical processes based on temperature, time and mechanical valve switching. Chemical agents are avoided. Trace amounts of interfering compounds can be separated by gas chromatography after pre-concentration of the CH4 sample. The purified sample is then either combusted to CO2 or pyrolyzed to H2 for stable isotope measurement. Apart from connecting samples and refilling liquid nitrogen as coolant the system is fully automated and allows an unobserved, continuous analysis of samples. The analytical system has been used for analysis of air samples with CH4 mixing ratios between ~100 and ~10 000 ppb, for higher mixing ratios samples usually have to be diluted.

  15. Oxidation resistant organic hydrogen getters

    DOEpatents

    Shepodd, Timothy J [Livermore, CA; Buffleben, George M [Tracy, CA

    2008-09-09

    A composition for removing hydrogen from an atmosphere, comprising a mixture of a polyphenyl ether and a hydrogenation catalyst, preferably a precious metal catalyst, and most preferably Pt. This composition is stable in the presence of oxygen, will not polymerize or degrade upon exposure to temperatures in excess of 200.degree. C., or prolonged exposure to temperatures in the range of 100-300.degree. C. Moreover, these novel hydrogen getter materials can be used to efficiently removing hydrogen from mixtures of hydrogen/inert gas (e.g., He, Ar, N.sub.2), hydrogen/ammonia atmospheres, such as may be encountered in heat exchangers, and hydrogen/carbon dioxide atmospheres. Water vapor and common atmospheric gases have no adverse effect on the ability of these getter materials to absorb hydrogen.

  16. Hydrogen cyanide production due to mid-size impacts in a redox-neutral N2-rich atmosphere.

    PubMed

    Kurosawa, Kosuke; Sugita, Seiji; Ishibashi, Ko; Hasegawa, Sunao; Sekine, Yasuhito; Ogawa, Nanako O; Kadono, Toshihiko; Ohno, Sohsuke; Ohkouchi, Naohiko; Nagaoka, Yoichi; Matsui, Takafumi

    2013-06-01

    Cyanide compounds are amongst the most important molecules of the origin of life. Here, we demonstrate the importance of mid-size (0.1-1 km in diameter) hence frequent meteoritic impacts to the cyanide inventory on the early Earth. Subsequent aerodynamic ablation and chemical reactions with the ambient atmosphere after oblique impacts were investigated by both impact and laser experiments. A polycarbonate projectile and graphite were used as laboratory analogs of meteoritic organic matter. Spectroscopic observations of impact-generated ablation vapors show that laser irradiation to graphite within an N2-rich gas can produce a thermodynamic environment similar to that produced by oblique impacts. Thus, laser ablation was used to investigate the final chemical products after this aerodynamic process. We found that a significant fraction (>0.1 mol%) of the vaporized carbon is converted to HCN and cyanide condensates, even when the ambient gas contains as much as a few hundred mbar of CO2. As such, the column density of cyanides after carbon-rich meteoritic impacts with diameters of 600 m would reach ~10 mol/m(2) over ~10(2) km(2) under early Earth conditions. Such a temporally and spatially concentrated supply of cyanides may have played an important role in the origin of life.

  17. Design and Validation of In-Source Atmospheric Pressure Photoionization Hydrogen/Deuterium Exchange Mass Spectrometry with Continuous Feeding of D2O

    NASA Astrophysics Data System (ADS)

    Acter, Thamina; Lee, Seulgidaun; Cho, Eunji; Jung, Maeng-Joon; Kim, Sunghwan

    2018-01-01

    In this study, continuous in-source hydrogen/deuterium exchange (HDX) atmospheric pressure photoionization (APPI) mass spectrometry (MS) with continuous feeding of D2O was developed and validated. D2O was continuously fed using a capillary line placed on the center of a metal plate positioned between the UV lamp and nebulizer. The proposed system overcomes the limitations of previously reported APPI HDX-MS approaches where deuterated solvents were premixed with sample solutions before ionization. This is particularly important for APPI because solvent composition can greatly influence ionization efficiency as well as the solubility of analytes. The experimental parameters for APPI HDX-MS with continuous feeding of D2O were optimized, and the optimized conditions were applied for the analysis of nitrogen-, oxygen-, and sulfur-containing compounds. The developed method was also applied for the analysis of the polar fraction of a petroleum sample. Thus, the data presented in this study clearly show that the proposed HDX approach can serve as an effective analytical tool for the structural analysis of complex mixtures. [Figure not available: see fulltext.

  18. Kinetic measurements of the reactivity of hydrogen peroxide and ozone towards small atmospherically relevant aldehydes, ketones and organic acids in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Schöne, L.; Herrmann, H.

    2014-05-01

    Free radical reactions are an important degradation process for organic compounds within the aqueous atmospheric environment. Nevertheless, non-radical oxidants such as hydrogen peroxide and ozone also contribute to the degradation and conversion of these substances (Tilgner and Herrmann, 2010). In this work, kinetic investigations of non-radical reactions were conducted using UV / Vis spectroscopy (dual-beam spectrophotometer and stopped flow technique) and a capillary electrophoresis system applying pseudo-first order kinetics to reactions of glyoxal, methylglyoxal, glycolaldehyde, glyoxylic, pyruvic and glycolic acid as well as methacrolein (MACR) and methyl vinyl ketone (MVK) with H2O2 and ozone at 298 K. The measurements indicate rather small rate constants at room temperature of k2nd < 3 M-1 s-1 (except for the unsaturated compounds exposed to ozone). Compared to radical reaction rate constants the values are about 10 orders of magnitude smaller (kOH • ~109 M-1 s-1). However, when considering the much larger non-radical oxidant concentrations compared to radical concentrations in urban cloud droplets, calculated first-order conversion rate constants change the picture towards H2O2 reactions becoming more important, especially when compared to the nitrate radical. For some reactions mechanistic suggestions are also given.

  19. Kinetic measurements on the reactivity of hydrogen peroxide and ozone towards small atmospherically relevant aldehydes, ketones and organic acids in aqueous solution

    NASA Astrophysics Data System (ADS)

    Schöne, L.; Herrmann, H.

    2013-10-01

    Within the aqueous atmospheric environment free radical reactions are an important degradation process for organic compounds. Nevertheless, non-radical oxidants like hydrogen peroxide and ozone also contribute to the degradation and conversion of this substance group (Tilgner und Herrmann, 2010). In this work kinetic investigations of non-radical reactions were conducted using UV/Vis spectroscopy (dual-beam spectrophotometer and Stopped Flow technique) and a capillary electrophoresis system applying pseudo-first order kinetics of glyoxal, methylglyoxal, glycolaldehyde, glyoxylic, pyruvic and glycolic acids as well as methacrolein (MACR) and methyl vinyl ketone (MVK) towards H2O2 and ozone. The measurements indicate rather small rate constants at room temperature of k2nd < 3 M-1 s-1 (except for the unsaturated compounds exposed to ozone). Compared to radical reaction rate constants the values are about 10 orders of magnitude smaller (kOH· ~ 109 M-1 s-1). However, when considering the much larger non-radical oxidant concentrations compared to radical concentrations in urban cloud droplets, calculated turnovers change the picture to more important H2O2 reactions especially when compared to the nitrate radical. For some reactions also mechanistic suggestions are given.

  20. The a 3Σg+ - b 3Σu+ Continuum Emission from Electron Impact of Molecular Hydrogen in Saturn's Atmosphere

    NASA Astrophysics Data System (ADS)

    Hein, J. D.; Johnson, P. V.; Liu, X.; Malone, C. P.; Khakoo, M. A.

    2014-12-01

    Shemansky et al. (2009, Planetary and Space Science 57: 1659-1670) have reported observations of hydrogen atoms flowing out of the top of Saturn's sunlit thermosphere in a confined, distinct plume of ballistic and escaping orbits, and a continuous distribution of H atoms from the top of Saturn's atmosphere to at least 45 Saturn radii (RS) in the satellite orbital plane and to 25 RS azimuthally above and below the plane. These observations have revealed the importance of the excitation of H2 by low energy electrons. H2 is efficiently excited to the triplet states by low energy electrons, and all triplet excitations result in the dissociation of H2 and the production of hot H atoms. Because of this, the electron impact excitation of H2 is an important energy deposition mechanism in the upper atmospheres of Saturn and other giant planets. The a 3Σg+ - b 3Σu continuum transition, which dominates all other H2 transitions in the 168-190 nm region, provides a unique spectral window through which the triplet transition can be observed with the Cassini spacecraft. The excitation and emission cross sections of the a 3Σg+ state and other triplet states are required for the extraction of the triplet emission and excitation rates from the apparent emission rate measured by the spacecraft. These emission and excitation rates, in turn, help to determine the energy deposition rate by electron impact excitation. Unfortunately, large discrepancies exist between published measurements of the a 3Σg+ - b 3Σu continuum transition. In order to begin to address this issue, we have recently revisited the problem by measuring electron impact induced a 3Σg+ - b 3Σu emission cross sections. We have also measured direct excitation cross sections of the triplet a 3Σg+ state. Using these, we are able to partition the excitation function into its direct and cascade components. As stated above, these results will enable improved understanding of phenomena observed in Saturn's atmosphere

  1. Measurement of atmospheric hydrogen peroxide and organic peroxides in Beijing before and during the 2008 Olympic Games: Chemical and physical factors influencing their concentrations

    NASA Astrophysics Data System (ADS)

    He, S. Z.; Chen, Z. M.; Zhang, X.; Zhao, Y.; Huang, D. M.; Zhao, J. N.; Zhu, T.; Hu, M.; Zeng, L. M.

    2010-09-01

    For the 2008 Beijing Olympic Games full-scale control (FSC) of atmospheric pollution was implemented to improve the air quality from 20 July to 20 September 2008, resulting in a significant decrease in the emission of pollutants in urban Beijing, especially vehicular emissions. The combination of reduced emissions and weather condition changes provided us with a unique opportunity to investigate urban atmospheric chemistry. Hydrogen peroxide (H2O2) and organic peroxides play significant roles in atmospheric processes, such as the cycling of HOx radicals and the formation of secondary sulfate aerosols and secondary organic aerosols. We measured atmospheric H2O2 and organic peroxides in urban Beijing, at the Peking University campus, from 12 July to 30 September, before and during the FSC. The major peroxides observed were H2O2, methyl hydroperoxide (MHP), and peroxyacetic acid (PAA), having maximal mixing ratios of 2.34, 0.95, and 0.17 ppbv (parts per billion by volume), respectively. Other organic peroxides were detected occasionally, such as bis-hydroxymethyl hydroperoxide, hydroxymethyl hydroperoxide, ethyl hydroperoxide, and 1-hydroxyethyl hydroperoxide. On sunny days the concentrations of H2O2, MHP, and PAA exhibited pronounced diurnal variations, with a peak in the afternoon (1500-1900) and, occasionally, a second peak in the evening (2000-0200). The night peaks can be attributed to local night production from the ozonolysis of alkenes, coupled with the reaction between NO3 radicals and organic compounds. Sunny-day weather dominated during 16-26 July, and we found that the concentrations of H2O2, MHP, and PAA increased strikingly on 22-26 July, compared with the concentrations during 16-19 July. This effect was mainly attributed to the NOx (NO and NO2) decline because of the FSC, due to (i) the suppressing effect of NO and NO2 on the production of peroxides and (ii) the indirect effect of reduced NOx on the concentration of peroxides via O3 production in the

  2. Hydrogen Sulfide Sequestration and Storage in Geothermal System: New Mitigation Strategy to Reduce H2S from the Atmosphere and Detect its Mineralization with Multiple Sulfur Isotopic Systematics

    NASA Astrophysics Data System (ADS)

    Marieni, C.; Stefansson, A.; Gudbrandsson, S.; Gunnarsson, I.; Aradottir, E. S.; Gunnarsson Robin, J.; Ono, S.

    2015-12-01

    Hydrogen sulfide (H2S) is one of the major components in geothermal fluids and is commonly emitted into the atmosphere from geothermal power plants causing potential environmental problems. Among several mitigation methods proposed to reduce the H2S emissions, is H2S sequestration into geothermal systems. Reykjavík Energy is undertaking a pilot project at Hellisheidi geothermal system (SW Iceland) called Sulfix project where H2S is being injected into the geothermal reservoir for permanent sequestration into pyrite. The SulFix project started its operation in June 2014: the soluble geothermal gases are dissolved in geothermal waste water, and injected at 8 bars into the high temperature reservoir (>200˚C) at 750 m below the wellhead. The reactions involving sulfur in the geothermal reservoir may be traced using sulfur fluid chemistry and multiple sulfur isotope systematics (32S, 33S, 34S and 36S), including mixing between the reservoir geothermal fluid and the injection fluid, sulfide mineralization and oxidation of sulfide to sulfate. In this study we investigated the multiple sulfur isotope systematics upon sulfide mineralization under geothermal conditions. High temperature flow through experiments were carried out in basaltic glass at 200-250°C and ~5 mmol/kg H2S to study the fluid-rock interaction. The results indicate that the sulfide mineralization occurs rapidly under geothermal conditions, highlighting the leaching rate of iron from the basaltic glass as the mineralization rate determining factor. Moreover, the formation of sulfide may be traced using the δ34S-Δ33S relationship in the fluids and pyrite formation - for example to determine if non-reactive mixing between the injection fluids and reservoir fluids occurs at Hellisheidi. The experimental results have been further supported by geochemical modeling involving multiple sulfur isotope fractionation between aqueous sulfide species and rocks upon basalt dissolution and secondary pyrite formation.

  3. Process for hydrogenating coal and coal solvents

    DOEpatents

    Tarrer, Arthur R.; Shridharani, Ketan G.

    1983-01-01

    A novel process is described for the hydrogenation of coal by the hydrogenation of a solvent for the coal in which the hydrogenation of the coal solvent is conducted in the presence of a solvent hydrogenation catalyst of increased activity, wherein the hydrogenation catalyst is produced by reacting ferric oxide with hydrogen sulfide at a temperature range of 260.degree. C. to 315.degree. C. in an inert atmosphere to produce an iron sulfide hydrogenation catalyst for the solvent. Optimally, the reaction temperature is 275.degree. C. Alternately, the reaction can be conducted in a hydrogen atmosphere at 350.degree. C.

  4. Hydrogen separation process

    DOEpatents

    Mundschau, Michael [Longmont, CO; Xie, Xiaobing [Foster City, CA; Evenson, IV, Carl; Grimmer, Paul [Longmont, CO; Wright, Harold [Longmont, CO

    2011-05-24

    A method for separating a hydrogen-rich product stream from a feed stream comprising hydrogen and at least one carbon-containing gas, comprising feeding the feed stream, at an inlet pressure greater than atmospheric pressure and a temperature greater than 200.degree. C., to a hydrogen separation membrane system comprising a membrane that is selectively permeable to hydrogen, and producing a hydrogen-rich permeate product stream on the permeate side of the membrane and a carbon dioxide-rich product raffinate stream on the raffinate side of the membrane. A method for separating a hydrogen-rich product stream from a feed stream comprising hydrogen and at least one carbon-containing gas, comprising feeding the feed stream, at an inlet pressure greater than atmospheric pressure and a temperature greater than 200.degree. C., to an integrated water gas shift/hydrogen separation membrane system wherein the hydrogen separation membrane system comprises a membrane that is selectively permeable to hydrogen, and producing a hydrogen-rich permeate product stream on the permeate side of the membrane and a carbon dioxide-rich product raffinate stream on the raffinate side of the membrane. A method for pretreating a membrane, comprising: heating the membrane to a desired operating temperature and desired feed pressure in a flow of inert gas for a sufficient time to cause the membrane to mechanically deform; decreasing the feed pressure to approximately ambient pressure; and optionally, flowing an oxidizing agent across the membrane before, during, or after deformation of the membrane. A method of supporting a hydrogen separation membrane system comprising selecting a hydrogen separation membrane system comprising one or more catalyst outer layers deposited on a hydrogen transport membrane layer and sealing the hydrogen separation membrane system to a porous support.

  5. Jupiter: Atmosphere

    NASA Astrophysics Data System (ADS)

    Drossart, P.; Murdin, P.

    2002-10-01

    In many aspects, JUPITER is intermediate between a planet and a star. As a star, it is mainly composed of hydrogen and helium, has an internal source of energy (although not from nuclear reactions) and has a convective interior (at least in part). As a planet, it experiences cold temperatures, receives energy from solar radiation in its atmosphere and shows a cloud structure with me...

  6. Reply to comment "On the hydrogen escape: Comment to variability of the hydrogen in the Martian upper atmosphere as simulated by a 3D atmosphere-exosphere coupling by J.-Y. Chaufray et al." by V. Krasnopolsky, Icarus, 281, 262

    NASA Astrophysics Data System (ADS)

    Chaufray, J.-Y.; Gonzalez-Galindo, F.; Forget, F.; Lopez-Valverde, M.; Leblanc, F.; Modolo, R.; Hess, S.

    2018-02-01

    Krasnopolsky (2017) makes a careful review of our recent results about the Martian hydrogen content of the Martian upper atmosphere (Chaufray et al., 2015). We comment here on his two major points. First, he suggests that the non-thermal escape of H2, and particularly collisions with hot oxygen, not taken into account in our general circulation model (GCM), should modify our reported H2 and H density profiles. This is an important issue; we acknowledge that future effective coupling of our GCM with comprehensive models of the Martian solar wind interaction, ideally after being validated with the latest plasma observations of H2+, would allow for better estimations of the relative importance of the H2 non-thermal and thermal escape processes. For the time being we need assumptions in the GCM, with proper and regular updates. According to a recent and detailed study of the anisotropic elastic and inelastic collision cross sections between O and H2 (Gacesa et al., 2012), the escape rates used by Krasnopolsky (2010) for this process might be overestimated. We therefore do not include non thermal escape of H2 in the model. And secondly, in response to Krasnopolsky's comment on the H escape variability with the solar cycle, we revised our calculations and found a small bug in the computation of the Jeans effusion velocity. Our revised computed H escape rates are included here. They have a small impact on our key conclusions: similar seasonal variations, a reduced variation with the solar cycle but still larger than Krasnopolsky (2017), and again a hydrogen scape systematically lower than the diffusion-limited flux. This bug does not affect the latest Mars Climate Database v5.2.

  7. Atmospheric hydrogen peroxide and organic hydroperoxides during PRIDE-PRD'06, China: their concentration, formation mechanism and contribution to secondary aerosols

    NASA Astrophysics Data System (ADS)

    Hua, W.; Chen, Z. M.; Jie, C. Y.; Kondo, Y.; Hofzumahaus, A.; Takegawa, N.; Chang, C. C.; Lu, K. D.; Miyazaki, Y.; Kita, K.; Wang, H. L.; Zhang, Y. H.; Hu, M.

    2008-11-01

    Atmospheric hydrogen peroxide (H2O2) and organic hydroperoxides were measured from 18 to 30 July in 2006 during the PRIDE-PRD'06 campaign at Backgarden, a rural site located 48 km north of Guangzhou, a mega-city in southern China. A ground-based instrument was used as a scrubbing coil collector to sample ambient air, followed by on-site analysis by high-performance liquid chromatography (HPLC) coupled with post-column derivatization and fluorescence detection. The H2O2 mixing ratio over the 13 days ranged from below the detection limit to a maximum of 4.6 ppbv, with a mean (and standard deviation) of (1.26±1.24) ppbv during the daytime (08:00 20:00 LT). Methyl hydroperoxide (MHP), with a maximum of 0.8 ppbv and a mean (and standard deviation) of (0.28±0.10) ppbv during the daytime, was the dominant organic hydroperoxide. Other organic peroxides, including bis-hydroxymethyl hydroperoxide (BHMP), peroxyacetic acid (PAA), hydroxymethyl hydroperoxide (HMHP), 1-hydroxy-ethyl hydroperoxide (1-HEHP) and ethyl hydroperoxide (EHP), were detected occasionally. The concentration of H2O2 exhibited a pronounced diurnal variation on sunny days, with a peak mixing ratio in the afternoon (12:00 18:00 LT), but lacked an explicit diurnal cycle on cloudy days. Sometimes a second peak mixing ratio of H2O2 was observed during the evening, suggesting that H2O2 was produced by the ozonolysis of alkenes. The diurnal variation profile of MHP was, in general, consistent with that of H2O2. The estimation indicated that in the morning the H2O2 detected was formed mostly through local photochemical activity, with the rest probably attributable to vertical transport. It is notable that relatively high levels of H2O2 and MHP were found in polluted air. The unexpectedly high level of HO2 radicals detected in this region can account for the production of hydroperoxides, while the moderate level of NOx suppressed the formation of hydroperoxides. High concentrations of hydroperoxides were detected

  8. Atmospheric hydrogen peroxide and organic hydroperoxides during PRIDE-PRD'06, China: their concentration, formation mechanism and contribution to secondary aerosols

    NASA Astrophysics Data System (ADS)

    Hua, W.; Chen, Z. M.; Jie, C. Y.; Kondo, Y.; Hofzumahaus, A.; Takegawa, N.; Lu, K. D.; Miyazaki, Y.; Kita, K.; Wang, H. L.; Zhang, Y. H.; Hu, M.

    2008-06-01

    Atmospheric hydrogen peroxide (H2O2) and organic hydroperoxides were measured from 18 to 30 July in 2006 during the PRIDE-PRD'06 campaign at Backgarden, a rural site located 48 km north of Guangzhou, a mega-city in southern China. A ground-based instrument was used as a scrubbing coil collector to sample ambient air, followed by on-site analysis by high-performance liquid chromatography (HPLC) coupled with post-column derivatization and fluorescence detection. The H2O2 mixing ratio over the 13 days ranged from below the detection limit to a maximum of 4.6 ppbv, with a mean (and standard deviation) of (1.26±1.24) ppbv during the daytime (08:00-20:00 LT). Methyl hydroperoxide (MHP), with a maximum of 0.8 ppbv and a mean (and standard deviation) of (0.28±0.10) ppbv during the daytime, was the dominant organic hydroperoxide. Other organic peroxides, including bis-hydroxymethyl hydroperoxide (BHMP), peroxyacetic acid (PAA), hydroxymethyl hydroperoxide (HMHP), 1-hydroxy-ethyl hydroperoxide (1-HEHP) and ethyl hydroperoxide (EHP), were detected occasionally. The concentration of H2O2 exhibited a pronounced diurnal variation on sunny days, with a peak mixing ratio in the afternoon (12:00-18:00 LT), but lacked an explicit diurnal cycle on cloudy days. Sometimes a second peak mixing ratio of H2O2 was observed during the evening, suggesting that H2O2 was produced by the ozonolysis of alkenes. The diurnal variation profile of MHP was, in general, consistent with that of H2O2. The estimation indicated that in the morning the H2O2 detected was formed mostly through local photochemical activity, with the rest probably attributable to vertical transport. It is notable that relatively high levels of H2O2 and MHP were found in polluted air. The unexpectedly high level of HO2 radicals detected in this region can account for the production of hydroperoxides, while the high level of NOx suppressed the formation of hydroperoxides significantly. High concentrations of hydroperoxides

  9. Seasonal cycles of atmospheric methane and its carbon and hydrogen isotopic ratios in the lower and upper troposphere of the western Pacific region

    NASA Astrophysics Data System (ADS)

    Umezawa, T.; Aoki, S.; Nakazawa, T.; Machida, T.; Matsueda, H.; Sawa, Y.; Ishijima, K.; Patra, P. K.

    2009-12-01

    Although carbon and hydrogen isotopic ratios (δ13C and δD) of CH4 provide useful information about its sources and sinks, systematic measurements were quite limited. Tohoku University group and NIES group have conducted air-sampling programs by using commercial container ships sailing between Japan and New Zealand and by using commercial airliners flying between Australia and Japan, respectively. Using air samples collected by the programs, systematic measurements of δ13C and δD of atmospheric CH4 as well as CH4 concentration ([CH4]) have been made since 2006. Here, we report their spatial and temporal variations in the lower and upper troposphere (LT and UT). In the LT of the northern hemisphere (NH), the seasonal cycle of [CH4] showed the maximum in winter and the minimum in summer. δ13C varied seasonally almost negatively correlating with the [CH4], and the seasonality of δD showed much more significant negative correlation with the [CH4]. It was also found that CH4 sources with seasonally varying strength, such as wetlands with high emissions in late summer, play an important role in the atmospheric CH4 variations. In the tropics, a seasonally-dependent air exchange between the NH and the southern hemisphere (SH) was found to characterize the seasonal CH4 cycle. When the NH and SH air arrived, high and low [CH4] were observed, accompanied by low and high δ13C and δD values, respectively. In the LT of the SH, the seasonal maximum and minimum of the [CH4] appeared in austral winter and summer, respectively. The seasonal CH4 cycle was mainly ascribed to the seasonality in the CH4+OH reaction, but δ13C and δD showed rather complicated seasonality with larger amplitudes than expected from the CH4+OH reaction alone, suggesting additional contribution of a CH4+Cl reaction in the marine boundary layer. In the UT of the NH, the seasonal maximum and minimum of the [CH4] appeared in summer and winter-spring, respectively, with low and high values of δ13C and

  10. Hydrogen environment embrittlement of metals

    NASA Technical Reports Server (NTRS)

    Jewett, R. P.; Walter, R. J.; Chandler, W. T.; Frohmberg, R. P.

    1973-01-01

    Hydrogen environment embrittlement refers to metals stressed while exposed to a hydrogen atmosphere. Tested in air, even after exposure to hydrogen under pressure, this effect is not observed on similar specimens. Much high purity hydrogen is prepared by evaporation of liquid hydrogen, and thus has low levels for potential impurities which could otherwise inhibit or poison the absorbent reactions that are involved. High strength steels and nickel-base allows are rated as showing extreme embrittlement; aluminum alloys and the austenitic stainless steels, as well as copper, have negligible susceptibility to this phenomenon. The cracking that occurs appears to be a surface phenomenon, is unlike that of internal hydrogen embrittlement.

  11. Carbon and hydrogen isotope composition and C-14 concentration in methane from sources and from the atmosphere: Implications for a global methane budget

    NASA Technical Reports Server (NTRS)

    Wahlen, Martin

    1994-01-01

    The topics covered include the following: biogenic methane studies; forest soil methane uptake; rice field methane sources; atmospheric measurements; stratospheric samples; Antarctica; California; and Germany.

  12. Polymer system for gettering hydrogen

    DOEpatents

    Shepodd, Timothy Jon; Whinnery, LeRoy L.

    2000-01-01

    A novel composition comprising organic polymer molecules having carbon-carbon double bonds, for removing hydrogen from the atmosphere within enclosed spaces. Organic polymers molecules containing carbon-carbon double bonds throughout their structures, preferably polybutadiene, polyisoprene and derivatives thereof, intimately mixed with an insoluble catalyst composition, comprising a hydrogenation catalyst and a catalyst support, preferably Pd supported on carbon, provide a hydrogen getter composition useful for removing hydrogen from enclosed spaces even in the presence of contaminants such as common atmospheric gases, water vapor, carbon dioxide, ammonia, oil mists, and water. The hydrogen getter composition disclosed herein is particularly useful for removing hydrogen from enclosed spaces containing potentially explosive mixtures of hydrogen and oxygen.

  13. Polymer formulations for gettering hydrogen

    DOEpatents

    Shepodd, Timothy Jon; Whinnery, LeRoy L.

    1998-11-17

    A novel composition comprising organic polymer molecules having carbon-carbon double bonds, for removing hydrogen from the atmosphere within enclosed spaces. Organic polymers molecules containing carbon-carbon double bonds throughout their structures, preferably polybutadiene, polyisoprene and derivatives thereof, intimately mixed with an insoluble catalyst composition, comprising a hydrogenation catalyst and a catalyst support, preferably Pd supported on carbon, provide a hydrogen getter composition useful for removing hydrogen from enclosed spaces even in the presence of contaminants such as common atmospheric gases, water vapor, carbon dioxide, ammonia, oil mists, and water. The hydrogen getter composition disclosed herein is particularly useful for removing hydrogen from enclosed spaces containing potentially explosive mixtures of hydrogen and oxygen.

  14. Polymer formulations for gettering hydrogen

    DOEpatents

    Shepodd, T.J.; Whinnery, L.L.

    1998-11-17

    A novel composition is described comprising organic polymer molecules having carbon-carbon double bonds, for removing hydrogen from the atmosphere within enclosed spaces. Organic polymers molecules containing carbon-carbon double bonds throughout their structures, preferably polybutadiene, polyisoprene and derivatives thereof, intimately mixed with an insoluble catalyst composition, comprising a hydrogenation catalyst and a catalyst support, preferably Pd supported on carbon, provide a hydrogen getter composition useful for removing hydrogen from enclosed spaces even in the presence of contaminants such as common atmospheric gases, water vapor, carbon dioxide, ammonia, oil mists, and water. The hydrogen getter composition disclosed herein is particularly useful for removing hydrogen from enclosed spaces containing potentially explosive mixtures of hydrogen and oxygen. 1 fig.

  15. Electrochemical Hydrogen Compressor

    SciTech Connect

    Lipp, Ludwig

    2016-01-21

    Conventional compressors have not been able to meet DOE targets for hydrogen refueling stations. They suffer from high capital cost, poor reliability and pose a risk of fuel contamination from lubricant oils. This project has significantly advanced the development of solid state hydrogen compressor technology for multiple applications. The project has achieved all of its major objectives. It has demonstrated capability of Electrochemical Hydrogen Compression (EHC) technology to potentially meet the DOE targets for small compressors for refueling sites. It has quantified EHC cell performance and durability, including single stage hydrogen compression from near-atmospheric pressure to 12,800 psi and operationmore » of EHC for more than 22,000 hours. Capital cost of EHC was reduced by 60%, enabling a path to meeting the DOE cost targets for hydrogen compression, storage and delivery ($2.00-2.15/gge by 2020).« less

  16. Method for absorbing hydrogen using an oxidation resisant organic hydrogen getter

    DOEpatents

    Shepodd, Timothy J [Livermore, CA; Buffleben, George M [Tracy, CA

    2009-02-03

    A composition for removing hydrogen from an atmosphere, comprising a mixture of a polyphenyl ether and a hydrogenation catalyst, preferably a precious metal catalyst, and most preferably platinum, is disclosed. This composition is stable in the presence of oxygen, will not polymerize or degrade upon exposure to temperatures in excess of 200.degree. C., or prolonged exposure to temperatures in the range of 100-300.degree. C. Moreover, these novel hydrogen getter materials can be used to efficiently remove hydrogen from mixtures of hydrogen/inert gas (e.g., He, Ar, N.sub.2), hydrogen/ammonia atmospheres, such as may be encountered in heat exchangers, and hydrogen/carbon dioxide atmospheres. Water vapor and common atmospheric gases have no adverse effect on the ability of these getter materials to absorb hydrogen.

  17. Organic chemistry in the atmosphere. [laboratory modeling of Titan atmosphere

    NASA Technical Reports Server (NTRS)

    Sagan, C.

    1974-01-01

    The existence of an at least moderately complex organic chemistry on Titan is stipulated based on clear evidence of methane, and at least presumptive evidence of hydrogen in its atmosphere. The ratio of methane to hydrogen is the highest of any atmosphere in the solar system. Irradiation of hydrogen/methane mixtures produces aromatic and aliphatic hydrocarbons. A very reasonable hypothesis assumes that the red cloud cover of Titan is made of organic chemicals. Two-carbon hydrocarbons experimentally produced from irradiated mixtures of methane, ammonia, water, and hydrogen bear out the possible organic chemistry of the Titanian environment.

  18. Hydrogen sensor

    DOEpatents

    Duan, Yixiang; Jia, Quanxi; Cao, Wenqing

    2010-11-23

    A hydrogen sensor for detecting/quantitating hydrogen and hydrogen isotopes includes a sampling line and a microplasma generator that excites hydrogen from a gas sample and produces light emission from excited hydrogen. A power supply provides power to the microplasma generator, and a spectrometer generates an emission spectrum from the light emission. A programmable computer is adapted for determining whether or not the gas sample includes hydrogen, and for quantitating the amount of hydrogen and/or hydrogen isotopes are present in the gas sample.

  19. Complex hydrides for hydrogen storage

    DOEpatents

    Zidan, Ragaiy

    2006-08-22

    A hydrogen storage material and process of forming the material is provided in which complex hydrides are combined under conditions of elevated temperatures and/or elevated temperature and pressure with a titanium metal such as titanium butoxide. The resulting fused product exhibits hydrogen desorption kinetics having a first hydrogen release point which occurs at normal atmospheres and at a temperature between 50.degree. C. and 90.degree. C.

  20. Hydrogenation apparatus

    DOEpatents

    Friedman, Joseph [Encino, CA; Oberg, Carl L [Canoga Park, CA; Russell, Larry H [Agoura, CA

    1981-01-01

    Hydrogenation reaction apparatus comprising a housing having walls which define a reaction zone and conduits for introducing streams of hydrogen and oxygen into the reaction zone, the oxygen being introduced into a central portion of the hydrogen stream to maintain a boundary layer of hydrogen along the walls of the reaction zone. A portion of the hydrogen and all of the oxygen react to produce a heated gas stream having a temperature within the range of from 1100.degree. to 1900.degree. C., while the boundary layer of hydrogen maintains the wall temperature at a substantially lower temperature. The heated gas stream is introduced into a hydrogenation reaction zone and provides the source of heat and hydrogen for a hydrogenation reaction. There also is provided means for quenching the products of the hydrogenation reaction. The present invention is particularly suitable for the hydrogenation of low-value solid carbonaceous materials to provide high yields of more valuable liquid and gaseous products.

  1. Hydrogen-powered flight

    NASA Technical Reports Server (NTRS)

    Smith, Timothy D.

    2005-01-01

    As the Nation moves towards a hydrogen economy the shape of aviation will change dramatically. To accommodate a switch to hydrogen the aircraft designs, propulsion, and power systems will look much different than the systems of today. Hydrogen will enable a number of new aircraft capabilities from high altitude long endurance remotely operated aircraft (HALE ROA) that will fly weeks to months without refueling to clean, zero emissions transport aircraft. Design and development of new hydrogen powered aircraft have a number of challenges which must be addressed before an operational system can become a reality. While the switch to hydrogen will be most outwardly noticeable in the aircraft designs of the future, other significant changes will be occurring in the environment. A switch to hydrogen for aircraft will completely eliminate harmful greenhouse gases such as carbon monoxide (CO), carbon dioxide (CO2), sulfur oxides (SOx), unburnt hydrocarbons and smoke. While these aircraft emissions are a small percentage of the amount produced on a daily basis, their placement in the upper atmosphere make them particularly harmful. Another troublesome gaseous emission from aircraft is nitrogen oxides (NOx) which contribute to ozone depletion in the upper atmosphere. Nitrogen oxide emissions are produced during the combustion process and are primarily a function of combustion temperature and residence time. The introduction of hydrogen to a gas turbine propulsion system will not eliminate NOx emissions; however the wide flammability range will make low NOx producing, lean burning systems feasible. A revolutionary approach to completely eliminating NOx would be to fly all electric aircraft powered by hydrogen air fuel cells. The fuel cells systems would only produce water, which could be captured on board or released in the lower altitudes. Currently fuel cell systems do not have sufficient energy densities for use in large aircraft, but the long term potential of eliminating

  2. Hydrogen gas from cured RTV silicones

    SciTech Connect

    Myers, L.C.

    1977-10-01

    Eight different RTV silicones were sealed in containers, and after preselected times the amount of hydrogen in the containers was determined. The silicone samples were conditioned at 80/sup 0/C in a 100% RH air atmosphere and at 23/sup 0/C in a dry air atmosphere. The amount of gas from duplicate samples varied considerably. The cause of these variations was investigated, and it was determined that humidity in a helium atmosphere produced the maximum hydrogen, and the amount of hydrogen is less if oxygen is present in the atmosphere. 10 figures, 3 tables.

  3. Escape of hydrogen from venus.

    PubMed

    McElroy, M B; Prather, M J; Rodriguez, J M

    1982-03-26

    Recombination of O(2)(+) represents a source of fast oxygen atoms in Venus' exosphere, and subsequent collisions of oxygen atoms with hydrogen atoms lead to escape of about 10(7) hydrogen atoms per square centimeter per second. Escape of deuterium atoms is negligible, and the ratio of deuterium to hydrogen should increase with time. It is suggested that the mass-2 ion observed by Pioneer Venus is D(+), which implies a ratio of deuterium to hydrogen in the contemporary atmosphere of about 10(-2), an initial ratio of 5 x 10(-5) and an original H(2)O abundance not less than 800 grams per square centimeter.

  4. Hydrogen in Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Peslier, A. H.; Hervig, R.; Irving, T.

    2017-01-01

    Most volatile studies of Mars have targeted its surface via spacecraft and rover data, and have evidenced surficial water in polar caps and the atmosphere, in the presence of river channels, and in the detection of water bearing minerals. The other focus of Martian volatile studies has been on Martian meteorites which are all from its crust. Most of these studies are on hydrous phases like apatite, a late-stage phase, i.e. crystallizing near the end of the differentiation sequence of Martian basalts and cumulates. Moreover, calculating the water content of the magma a phosphate crystallized from is not always possible, and yet is an essential step to estimate how much water was present in a parent magma and its source. Water, however, is primarily dissolved in the interiors of differentiated planets as hydrogen in lattice defects of nominally anhydrous minerals (olivine, pyroxene, feldspar) of the crust and mantle. This hydrogen has tremendous influence, even in trace quantities, on a planet's formation, geodynamics, cooling history and the origin of its volcanism and atmosphere as well as its potential for life. Studies of hydrogen in nominally anhydrous phases of Martian meteorites are rare. Measuring water contents and hydrogen isotopes in well-characterized nominally anhydrous minerals of Martian meteorites is the goal of our study. Our work aims at deciphering what influences the distribution and origin of hydrogen in Martian minerals, such as source, differentiation, degassing and shock.

  5. Hydrogenation apparatus

    DOEpatents

    Friedman, J.; Oberg, C. L.; Russell, L. H.

    1981-06-23

    Hydrogenation reaction apparatus is described comprising a housing having walls which define a reaction zone and conduits for introducing streams of hydrogen and oxygen into the reaction zone, the oxygen being introduced into a central portion of the hydrogen stream to maintain a boundary layer of hydrogen along the walls of the reaction zone. A portion of the hydrogen and all of the oxygen react to produce a heated gas stream having a temperature within the range of from 1,100 to 1,900 C, while the boundary layer of hydrogen maintains the wall temperature at a substantially lower temperature. The heated gas stream is introduced into a hydrogenation reaction zone and provides the source of heat and hydrogen for a hydrogenation reaction. There also is provided means for quenching the products of the hydrogenation reaction. The present invention is particularly suitable for the hydrogenation of low-value solid carbonaceous materials to provide high yields of more valuable liquid and gaseous products. 2 figs.

  6. Color Changing Hydrogen Sensors

    NASA Technical Reports Server (NTRS)

    Roberson, Luke B.; Williams, Martha; Captain, Janine E.; Mohajeri, Nahid; Raissi, Ali

    2015-01-01

    During the Space Shuttle Program, one of the most hazardous operation that occurred was the loading of liquid hydrogen (LH2) during fueling operations of the spacecraft. Due to hydrogen's low explosive limit, any amount leaked could lead to catastrophic event. Hydrogen's chemical properties make it ideal as a rocket fuel; however, the fuel is deemed unsafe for most commercial use because of the inability to easily detect the gas leaking. The increased use of hydrogen over traditional fossil fuels would reduce greenhouse gases and America's dependency on foreign oil. Therefore a technology that would improve safety at NASA and in the commercial sector while creating a new economic sector would have a huge impact to NASA's mission. The Chemochromic Detector for sensing hydrogen gas leakage is a color-changing detector that is useful in any application where it is important to know not only the presence but also the location of the hydrogen gas leak. This technology utilizes a chemochromicpigment and polymer matrix that can be molded or spun into rigid or pliable shapes useable in variable temperature environments including atmospheres of inert gas, hydrogen gas, or mixtures of gases. A change in color of the detector material indicates where gaseous hydrogen leaks are occurring. The irreversible sensor has a dramatic color change from beige to dark grey and remains dark grey after exposure. A reversible pigment changes from white to blue in the presence of hydrogen and reverts back to white in the presence of oxygen. Both versions of the sensor's pigments were comprised of a mixture of a metal oxide substrate and a hydro-chromic compound (i.e., the compound that changed color in the presence of hydrogen) and immediately notified the operator of the presence of low levels of hydrogen. The detector can be used in a variety of formats including paint, tape, caulking, injection molded parts, textiles and fabrics, composites, and films. This technology brings numerous

  7. Sulfur and phosphorus distribution between liquid iron and magnesia-saturated slag in molecular hydrogen/water atmosphere relevant to a novel green ironmaking technology

    NASA Astrophysics Data System (ADS)

    Mohassab Ahmed, Mohassab Yousef

    As an integral part of a research project which aimed to develop a novel green ironmaking process, an experimental determination of the sulfur and phosphorus distribution ratios, LS and LP, respectively, between molten iron and CaO-MgO(Saturated)-SiO2-Al 3O3-FeO slag was determined in the temperature range 1550-1650°C. Oxygen partial pressure was controlled by H2/H2O equilibrium in the range of 10-10-10-8 atm. For sulfur distribution, it was found that the trend of the distribution is the same as the previous work done under CO/CO2 atmosphere but LS in this case is 38-44 times less under similar oxygen partial pressure. This might be attributed to the impact of H2 on the distribution. Considering the fact that the input sulfur in the proposed process is approximately 34 times less than the blast furnace process, the proposed process would produce hot metal with approximately the same sulfur content to the hot metal produced by the blast furnace. For phosphorus distribution, LP was 450-1050 times that of the blast furnace. Also considering the amount of phosphorus input in the two processes, it was found that the expected P content in iron in the new process would be approximately three times less than in the blast furnace hot metal. This means that the proposed process will produce hot metal with much lower phosphorus which will minimize the need for dephosphorization in the steelmaking stage.

  8. Atmospheric Pseudohalogen Chemistry

    NASA Technical Reports Server (NTRS)

    Lary, David John

    2004-01-01

    Hydrogen cyanide is not usually considered in atmospheric chemical models. The paper presents three reasons why hydrogen cyanide is likely to be significant for atmospheric chemistry. Firstly, HCN is a product and marker of biomass burning. Secondly, it is also likely that lightning is producing HCN, and as HCN is sparingly soluble it could be a useful long-lived "smoking gun" marker of lightning activity. Thirdly, the chemical decomposition of HCN leads to the production of small amounts of the cyanide (CN) and NCO radicals. The NCO radical can be photolyzed in the visible portion of the spectrum yielding nitrogen atoms (N). The production of nitrogen atoms is significant as it leads to the titration of total nitrogen from the atmosphere via N+N->N2, where N2 is molecular nitrogen.

  9. Hydrogen Embrittlement

    NASA Technical Reports Server (NTRS)

    Woods, Stephen; Lee, Jonathan A.

    2016-01-01

    Hydrogen embrittlement (HE) is a process resulting in a decrease in the fracture toughness or ductility of a metal due to the presence of atomic hydrogen. In addition to pure hydrogen gas as a direct source for the absorption of atomic hydrogen, the damaging effect can manifest itself from other hydrogen-containing gas species such as hydrogen sulfide (H2S), hydrogen chloride (HCl), and hydrogen bromide (HBr) environments. It has been known that H2S environment may result in a much more severe condition of embrittlement than pure hydrogen gas (H2) for certain types of alloys at similar conditions of stress and gas pressure. The reduction of fracture loads can occur at levels well below the yield strength of the material. Hydrogen embrittlement is usually manifest in terms of singular sharp cracks, in contrast to the extensive branching observed for stress corrosion cracking. The initial crack openings and the local deformation associated with crack propagation may be so small that they are difficult to detect except in special nondestructive examinations. Cracks due to HE can grow rapidly with little macroscopic evidence of mechanical deformation in materials that are normally quite ductile. This Technical Memorandum presents a comprehensive review of experimental data for the effects of gaseous Hydrogen Environment Embrittlement (HEE) for several types of metallic materials. Common material screening methods are used to rate the hydrogen degradation of mechanical properties that occur while the material is under an applied stress and exposed to gaseous hydrogen as compared to air or helium, under slow strain rates (SSR) testing. Due to the simplicity and accelerated nature of these tests, the results expressed in terms of HEE index are not intended to necessarily represent true hydrogen service environment for long-term exposure, but rather to provide a practical approach for material screening, which is a useful concept to qualitatively evaluate the severity of

  10. Reversible Chemochromic Hydrogen Detectors

    NASA Technical Reports Server (NTRS)

    2008-01-01

    The Florida Solar Energy Center (FSEC), affiliated with the University of Central Florida, has invented a reversible pigment that changes from light beige to blue when exposed to hydrogen and back to light beige when exposed to atmospheric oxygen. In laboratory and environmental studies, the FSEC pigment in its tape form failed to change color adequately when exposed to hydrogen after one day of exposure at Kennedy Space Center's Beach Corrosion Test Facility. The reversible hydrogen-detecting tape also lost its ability to change color after being placed in an environmental chamber at 45 C for one day. The first attempts at extruding the reversible pigment into various polymers were unsuccessful because of the pigment's poor thermal stability. The goal of this project was to formulate a pigment with improved thermal and environmental stability for extrusion into a variety of appropriate polymer matrices. The formulation of the reversible hydrogen-detecting pigment was modified by removing one reagent and chemically modifying the hydrogen sensitive ingredient. This was intended to improve the hydrophobicity of the pigment and alter the thermal degradation mechanism.

  11. Freezing Hydrogen

    NASA Image and Video Library

    2009-11-17

    An engineer loads hydrogen gas into the Wide-Field Infrared Survey Explorer in a clean room at the Vandenberg Air Force Base, Calif. The hydrogen is cooled and frozen inside a Thermos-like bottle, called the cryostat, which keeps the science instrument

  12. Synthesis of hydrogen-carbon clathrate material and hydrogen evolution therefrom at moderate temperatures and pressures

    DOEpatents

    Lueking, Angela [State College, PA; Narayanan, Deepa [Redmond, WA

    2011-03-08

    A process for making a hydrogenated carbon material is provided which includes forming a mixture of a carbon source, particularly a carbonaceous material, and a hydrogen source. The mixture is reacted under reaction conditions such that hydrogen is generated and/or released from the hydrogen source, an amorphous diamond-like carbon is formed, and at least a portion of the generated and/or released hydrogen associates with the amorphous diamond-like carbon, thereby forming a hydrogenated carbon material. A hydrogenated carbon material including a hydrogen carbon clathrate is characterized by evolution of molecular hydrogen at room temperature at atmospheric pressure in particular embodiments of methods and compositions according to the present invention.

  13. Hydrogen energy.

    PubMed

    Edwards, P P; Kuznetsov, V L; David, W I F

    2007-04-15

    The problem of anthropogenically driven climate change and its inextricable link to our global society's present and future energy needs are arguably the greatest challenge facing our planet. Hydrogen is now widely regarded as one key element of a potential energy solution for the twenty-first century, capable of assisting in issues of environmental emissions, sustainability and energy security. Hydrogen has the potential to provide for energy in transportation, distributed heat and power generation and energy storage systems with little or no impact on the environment, both locally and globally. However, any transition from a carbon-based (fossil fuel) energy system to a hydrogen-based economy involves significant scientific, technological and socio-economic barriers. This brief report aims to outline the basis of the growing worldwide interest in hydrogen energy and examines some of the important issues relating to the future development of hydrogen as an energy vector.

  14. Differential atmospheric tritium sampler

    DOEpatents

    Griesbach, Otto A.; Stencel, Joseph R.

    1990-01-01

    An atmospheric tritium sampler is provided which uses a carrier gas comprised of hydrogen gas and a diluting gas, mixed in a nonexplosive concentration. Sample air and carrier gas are drawn into and mixed in a manifold. A regulator meters the carrier gas flow to the manifold. The air sample/carrier gas mixture is pulled through a first moisture trap which adsorbs water from the air sample. The mixture then passes through a combustion chamber where hydrogen gas in the form of H.sub.2 or HT is combusted into water. The manufactured water is transported by the air stream to a second moisture trap where it is adsorbed. The air is then discharged back into the atmosphere by means of a pump.

  15. Differential atmospheric tritium sampler

    DOEpatents

    Griesbach, O.A.; Stencel, J.R.

    1987-10-02

    An atmospheric tritium sampler is provided which uses a carrier gas comprised of hydrogen gas and a diluting gas, mixed in a nonexplosive concentration. Sample air and carrier gas are drawn into and mixed in a manifold. A regulator meters the carrier gas flow to the manifold. The air sample/carrier gas mixture is pulled through a first moisture trap which adsorbs water from the air sample. The moisture then passes through a combustion chamber where hydrogen gas in the form of H/sub 2/ or HT is combusted into water. The manufactured water is transported by the air stream to a second moisture trap where it is adsorbed. The air is then discharged back into the atmosphere by means of a pump.

  16. Influence of high pressure hydrogen environment on creep deformation of Mo-Re, Haynes 188, and NARloy-Z alloys

    NASA Technical Reports Server (NTRS)

    Sastry, S. M. L.; Yang, Charles C.; Ouyang, Shewang; Jerina, K. L.; Schwartz, D. S.

    1994-01-01

    The present study focuses on the investigation of the influence of hydrogen on the mechanical properties of three types of alloys at elevated temperatures. The reasons for the consideration of hydrogen effects are the potential use of hydrogen as a coolant in gas-cooled reactors and fuel in advanced hypersonic vehicles. The materials used in hydrogen atmosphere must not be embrittled by hydrogen at ambient temperature and should have good strength in hydrogen atmosphere at elevated temperature. The paucity of information concerning the mechanical performance in hydrogen atmosphere at elevated temperature has been a limiting factor in the selection and design of structural components for operation in hydrogen environment.

  17. Explosion-combustion in exoplanetary atmospheres

    NASA Astrophysics Data System (ADS)

    Grenfell, John Lee; Godolt, Mareike; Stracke, Barbara; Gebauer, Stefanie; Rauer, Heike

    2017-04-01

    Conditions leading to explosion or/and combustion in exoplanetary atmospheres are investigated for different atmospheric composition, temperature and pressure. Cases considered are Super-Earths orbiting in the habitable zone of M-dwarf stars with atmospheres consisting of abiotically-produced molecular oxygen together with molecular hydrogen accreted from the protoplanetary disk. Should these atmospheres undergo hydrogen-oxygen combustion triggered by e.g. lightning or cosmic rays, this would limit the build-up of abiotic oxygen, lower the hydrogen gas envelope and could lead to liquid oceans with masses tens to hundreds of times larger than on the Earth. We also consider other explosive-combustive gas mixtures which could lead to carbon monoxide or methane combustion in the atmospheres of some Mini Gas Planets or in (Early) Earth-like atmospheres.

  18. A Volcanic Hydrogen Habitable Zone

    SciTech Connect

    Ramirez, Ramses M.; Kaltenegger, Lisa, E-mail: rmr277@cornell.edu

    2017-03-01

    The classical habitable zone (HZ) is the circular region around a star in which liquid water could exist on the surface of a rocky planet. The outer edge of the traditional N{sub 2}–CO{sub 2}–H{sub 2}O HZ extends out to nearly ∼1.7 au in our solar system, beyond which condensation and scattering by CO{sub 2} outstrips its greenhouse capacity. Here, we show that volcanic outgassing of atmospheric H{sub 2} can extend the outer edge of the HZ to ∼2.4 au in our solar system. This wider volcanic-hydrogen HZ (N{sub 2}–CO{sub 2}–H{sub 2}O–H{sub 2}) can be sustained as long as volcanic H{submore » 2} output offsets its escape from the top of the atmosphere. We use a single-column radiative-convective climate model to compute the HZ limits of this volcanic hydrogen HZ for hydrogen concentrations between 1% and 50%, assuming diffusion-limited atmospheric escape. At a hydrogen concentration of 50%, the effective stellar flux required to support the outer edge decreases by ∼35%–60% for M–A stars. The corresponding orbital distances increase by ∼30%–60%. The inner edge of this HZ only moves out ∼0.1%–4% relative to the classical HZ because H{sub 2} warming is reduced in dense H{sub 2}O atmospheres. The atmospheric scale heights of such volcanic H{sub 2} atmospheres near the outer edge of the HZ also increase, facilitating remote detection of atmospheric signatures.« less

  19. Polymer formulations for gettering hydrogen

    DOEpatents

    Shepodd, Timothy J.; Even, Jr., William R.

    2000-01-01

    A novel method for preparing a hydrogenation composition comprising organic polymer molecules having carbon--carbon double bonds, for removing hydrogen from the atmosphere within enclosed spaces and particularly from atmospheres within enclosed spaces that contain air, water vapor, oxygen, carbon dioxide or ammonia. The organic polymers molecules containing carbon--carbon double bonds throughout their structures, preferably polybutadiene, polyisoprene and derivatives thereof, intimately mixed with an insoluble noble metal catalyst composition. High molecular weight polymers may be added to the organic polymer/catalyst mixture in order to improve their high temperature performance. The hydrogenation composition is prepared by dispersing the polymers in a suitable solvent, forming thereby a solution suspension, flash-freezing droplets of the solution in a liquid cryogen, freeze-drying the frozen droplets to remove frozen solvent incorporated in the droplets, and recovering the dried powder thus formed.

  20. Modeling leaks from liquid hydrogen storage systems.

    SciTech Connect

    Winters, William Stanley, Jr.

    2009-01-01

    This report documents a series of models for describing intended and unintended discharges from liquid hydrogen storage systems. Typically these systems store hydrogen in the saturated state at approximately five to ten atmospheres. Some of models discussed here are equilibrium-based models that make use of the NIST thermodynamic models to specify the states of multiphase hydrogen and air-hydrogen mixtures. Two types of discharges are considered: slow leaks where hydrogen enters the ambient at atmospheric pressure and fast leaks where the hydrogen flow is usually choked and expands into the ambient through an underexpanded jet. In order to avoid the complexitiesmore » of supersonic flow, a single Mach disk model is proposed for fast leaks that are choked. The velocity and state of hydrogen downstream of the Mach disk leads to a more tractable subsonic boundary condition. However, the hydrogen temperature exiting all leaks (fast or slow, from saturated liquid or saturated vapor) is approximately 20.4 K. At these temperatures, any entrained air would likely condense or even freeze leading to an air-hydrogen mixture that cannot be characterized by the REFPROP subroutines. For this reason a plug flow entrainment model is proposed to treat a short zone of initial entrainment and heating. The model predicts the quantity of entrained air required to bring the air-hydrogen mixture to a temperature of approximately 65 K at one atmosphere. At this temperature the mixture can be treated as a mixture of ideal gases and is much more amenable to modeling with Gaussian entrainment models and CFD codes. A Gaussian entrainment model is formulated to predict the trajectory and properties of a cold hydrogen jet leaking into ambient air. The model shows that similarity between two jets depends on the densimetric Froude number, density ratio and initial hydrogen concentration.« less

  1. Hydrogen Embrittlement of Nickel.

    DTIC Science & Technology

    1984-10-01

    temperature dependence of sulfur coverage of Ni surfaces in equilibrium with solute sulfur and H2S gas has been examined by Miyahara et al( 37 ) using...cm 3 of nickel, PH is hydrogen pressure in atmospheres, T is the charging temperature in degrees KelvinAH is the heat of solution (3700 cal/mole), C0...35 3.2 Dislocation Transport . ... ..........."’ rcue35 3.2.1 Effect of Test Temperature on Fracture . . . . . . . . . . 39 3.2.2 Effect of Strain

  2. Hydroperoxides as Hydrogen Bond Donors

    NASA Astrophysics Data System (ADS)

    Møller, Kristian H.; Tram, Camilla M.; Hansen, Anne S.; Kjaergaard, Henrik G.

    2016-06-01

    Hydroperoxides are formed in the atmosphere following autooxidation of a wide variety of volatile organics emitted from both natural and anthropogenic sources. This raises the question of whether they can form hydrogen bonds that facilitate aerosol formation and growth. Using a combination of Fourier transform infrared spectroscopy, FT-IR, and ab initio calculations, we have compared the gas phase hydrogen bonding ability of tert-butylhydroperoxide (tBuOOH) to that of tert-butanol (tBuOH) for a series of bimolecular complexes with different acceptors. The hydrogen bond acceptor atoms studied are nitrogen, oxygen, phosphorus and sulphur. Both in terms of calculated redshifts and binding energies (BE), our results suggest that hydroperoxides are better hydrogen bond donors than the corresponding alcohols. In terms of hydrogen bond acceptor ability, we find that nitrogen is a significantly better acceptor than the other three atoms, which are of similar strength. We observe a similar trend in hydrogen bond acceptor ability with other hydrogen bond donors including methanol and dimethylamine.

  3. Method of producing hydrogenated amorphous silicon film

    DOEpatents

    Wiesmann, Harold J.

    1980-01-01

    This invention relates to hydrogenated amorphous silicon produced by thermally decomposing silane (SiH.sub.4) or other gases comprising H and Si, from a tungsten or carbon foil heated to a temperature of about 1400.degree.-1600.degree. C., in a vacuum of about 10.sup.-6 to 19.sup.-4 torr, to form a gaseous mixture of atomic hydrogen and atomic silicon, and depositing said gaseos mixture onto a substrate independent of and outside said source of thermal decomposition, to form hydrogenated amorphous silicon. The presence of an ammonia atmosphere in the vacuum chamber enhances the photoconductivity of the hydrogenated amorphous silicon film.

  4. Hydrogen program overview

    SciTech Connect

    Gronich, S.

    1997-12-31

    This paper consists of viewgraphs which summarize the following: Hydrogen program structure; Goals for hydrogen production research; Goals for hydrogen storage and utilization research; Technology validation; DOE technology validation activities supporting hydrogen pathways; Near-term opportunities for hydrogen; Market for hydrogen; and List of solicitation awards. It is concluded that a full transition toward a hydrogen economy can begin in the next decade.

  5. How to Make a Helium Atmosphere

    NASA Image and Video Library

    2015-06-11

    This diagram illustrates how hypothetical helium atmospheres might form. These would be on planets about the mass of Neptune, or smaller, which orbit tightly to their stars, whipping around in just days. They are thought to have cores of water or rock, surrounded by thick atmospheres of gas. Radiation from their nearby stars would boil off hydrogen and helium, but because hydrogen is lighter, more hydrogen would escape. It's also possible that planetary bodies, such as asteroids, could impact the planet, sending hydrogen out into space. Over time, the atmospheres would become enriched in helium. With less hydrogen in the planets' atmospheres, the concentration of methane and water would go down. Both water and methane consist in part of hydrogen. Eventually, billions of years later (a "Gyr" equals one billion years), the abundances of the water and methane would be greatly reduced. Since hydrogen would not be abundant, the carbon would be forced to pair with oxygen, forming carbon monoxide. NASA's Spitzer Space Telescope observed a proposed helium planet, GJ 436b, with these traits: it lacks methane, and appears to contain carbon monoxide. Future observations are needed to detect helium itself in the atmospheres of these planets, and confirm this theory. http://photojournal.jpl.nasa.gov/catalog/PIA19345

  6. Photovoltaic hydrogen production

    SciTech Connect

    Hiser, H.W.; Memory, S.B.; Veziroglu, T.N.

    1996-10-01

    This is a new project, which started in June 1995, and involves photovoltaic hydrogen production as a fuel production method for the future. In order to increase the hydrogen yield, it was decided to use hybrid solar collectors to generate D.C. electricity, as well as high temperature steam for input to the electrolyzer. In this way, some of the energy needed to dissociate the water is supplied in the form of heat (or low grade energy), to generate steam, which results in a reduction of electrical energy (or high grade energy) needed. As a result, solar to hydrogen conversion efficiencymore » is increased. In the above stated system, the collector location, the collector tracking sub-system (i.e., orientation/rotation), and the steam temperature have been taken as variables. Five locations selected - in order to consider a variety of latitudes, altitudes, cloud coverage and atmospheric conditions - are Atlanta, Denver, Miami, Phoenix and Salt Lake City. Plain PV and hybrid solar collectors for a stationary south facing system and five different collector rotation systems have been analyzed. Steam temperatures have been varied between 200{degrees}C and 1200{degrees}C. During the first year, solar to hydrogen conversion efficiencies have been considered. The results show that higher steam temperatures, 2 dimensional tracking system, higher elevations and dryer climates causes higher conversion efficiencies. Cost effectiveness of the sub-systems and of the overall system will be analyzed during the second year. Also, initial studies will be made of an advanced high efficiency hybrid solar hydrogen production system.« less

  7. Scientific summary. [composition of Titan atmospheric models

    NASA Technical Reports Server (NTRS)

    Hunten, D. M.

    1974-01-01

    Methane absorptions are prominent in the Titan atmospheric spectrum; also present are atomic hydrogen and nitrogen bands. Evaluation of the low ultraviolet albedo points to solid methane clouds and photochemical haze. Thermal infrared data indicate solar energy absorption and photodissociation reactions of the gas mixture resulting in the production of organic compounds and free hydrogen atoms.

  8. The early atmosphere - A new picture

    NASA Technical Reports Server (NTRS)

    Levine, Joel S.

    1986-01-01

    Over the last few years, discoveries in astronomy, geochemistry, and atmospheric chemistry have resulted in a new picture of how our planet and its atmosphere formed. The traditional view held that the early atmosphere was composed of methane, ammonia, and molecular hydrogen, but the actual composition may have been nitrogen, carbon dioxide, and water vapor. The history leading to the present understanding is discussed and topics covered include: chemical evolution, origin of the atmosphere, atmospheric evolution on earth, Venus, and Mars, and prebiological atmospheric oxygen and the early sun.

  9. Survey of Hydrogen Combustion Properties

    NASA Technical Reports Server (NTRS)

    Drell, Isadore L; Belles, Frank E

    1958-01-01

    This literature digest of hydrogen-air combustion fundamentals presents data on flame temperature, burning velocity, quenching distance, flammability limits, ignition energy, flame stability, detonation, spontaneous ignition, and explosion limits. The data are assessed, recommended values are given, and relations among various combustion properties are discussed. New material presented includes: theoretical treatment of variation in spontaneous ignition lag with temperature, pressure, and composition, based on reaction kinetics of hydrogen-air composition range for 0.01 to 100 atmospheres and initial temperatures of 0 degrees to 1400 degrees k.

  10. Hydrogen chloride

    Integrated Risk Information System (IRIS)

    Hydrogen chloride ; CASRN 7647 - 01 - 0 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogeni

  11. Hydrogen sulfide

    Integrated Risk Information System (IRIS)

    EPA / 635 / R - 03 / 005 www.epa.gov / iris TOXICOLOGICAL REVIEW OF HYDROGEN SULFIDE ( CAS No . 7783 - 06 - 4 ) In Support of Summary Information on the Integrated Risk Information System ( IRIS ) June 2003 U.S . Environmental Protection Agency Washington , DC DISCLAIMER This document has been

  12. Positron Spectroscopy of Nanodiamonds after Hydrogen Sorption.

    PubMed

    Nikitina, Lyudmila; Laptev, Roman; Abzaev, Yuri; Lider, Andrey; Ivashutenko, Alexander

    2018-01-11

    The structure and defects of nanodiamonds influence the hydrogen sorption capacity. Positronium can be used as a sensor for detecting places with the most efficient capture of hydrogen atoms. Hydrogenation of carbon materials was performed from gas atmosphere. The concentration of hydrogen absorbed by the sample depends on the temperature and pressure. The concentration 1.2 wt % is achieved at the temperature of 243 K and the pressure of 0.6 MPa. The hydrogen saturation of nanodiamonds changes the positron lifetime. Increase of sorption cycle numbers effects the positron lifetime, as well as the parameters of the Doppler broadening of annihilation line. The electron-positron annihilation being a sensitive method, it allows detecting the electron density fluctuation of the carbon material after hydrogen saturation.

  13. Cryogenic hydrogen-induced air liquefaction technologies

    NASA Technical Reports Server (NTRS)

    Escher, William J. D.

    1990-01-01

    Extensively utilizing a special advanced airbreathing propulsion archives database, as well as direct contacts with individuals who were active in the field in previous years, a technical assessment of cryogenic hydrogen-induced air liquefaction, as a prospective onboard aerospace vehicle process, was performed and documented. The resulting assessment report is summarized. Technical findings are presented relating the status of air liquefaction technology, both as a singular technical area, and also that of a cluster of collateral technical areas including: compact lightweight cryogenic heat exchangers; heat exchanger atmospheric constituents fouling alleviation; para/ortho hydrogen shift conversion catalysts; hydrogen turbine expanders, cryogenic air compressors and liquid air pumps; hydrogen recycling using slush hydrogen as heat sink; liquid hydrogen/liquid air rocket-type combustion devices; air collection and enrichment systems (ACES); and technically related engine concepts.

  14. Positron Spectroscopy of Nanodiamonds after Hydrogen Sorption

    PubMed Central

    Laptev, Roman; Abzaev, Yuri; Lider, Andrey; Ivashutenko, Alexander

    2018-01-01

    The structure and defects of nanodiamonds influence the hydrogen sorption capacity. Positronium can be used as a sensor for detecting places with the most efficient capture of hydrogen atoms. Hydrogenation of carbon materials was performed from gas atmosphere. The concentration of hydrogen absorbed by the sample depends on the temperature and pressure. The concentration 1.2 wt % is achieved at the temperature of 243 K and the pressure of 0.6 MPa. The hydrogen saturation of nanodiamonds changes the positron lifetime. Increase of sorption cycle numbers effects the positron lifetime, as well as the parameters of the Doppler broadening of annihilation line. The electron-positron annihilation being a sensitive method, it allows detecting the electron density fluctuation of the carbon material after hydrogen saturation. PMID:29324712

  15. Hydrogen safety manual

    NASA Technical Reports Server (NTRS)

    1968-01-01

    Hydrogen safety manual covers the characteristics and nature of hydrogen, design principles for hydrogen systems, protection of personnel and equipment, and operating and emergency procedures. It sets standards and practices for minimum safety requirements at hydrogen installations.

  16. Atmospheric lab

    NASA Astrophysics Data System (ADS)

    A new $11.3 million Atmospheric Emergency Response Facility is under construction at the Lawrence Livermore National Laboratory in Calif. The facility, which will take 18 months to build, will house Livermore's Atmospheric Release Advisory Capability (ARAC) and research components of the Regional Atmospheric Sciences (RAS) division, which have been housed in trailers for the past 17 years. Along with studying the effects of episodic releases of hazardous materials in the atmosphere, the RAS division also is working on developing atmospheric models on a variety of space scales.

  17. Hydrogen scavengers

    DOEpatents

    Carroll, David W.; Salazar, Kenneth V.; Trkula, Mitchell; Sandoval, Cynthia W.

    2002-01-01

    There has been invented a codeposition process for fabricating hydrogen scavengers. First, a .pi.-bonded allylic organometallic complex is prepared by reacting an allylic transition metal halide with an organic ligand complexed with an alkali metal; and then, in a second step, a vapor of the .pi.-bonded allylic organometallic complex is combined with the vapor of an acetylenic compound, irradiated with UV light, and codeposited on a substrate.

  18. Atmospheric neutrons

    NASA Technical Reports Server (NTRS)

    Korff, S. A.; Mendell, R. B.; Merker, M.; Light, E. S.; Verschell, H. J.; Sandie, W. S.

    1979-01-01

    Contributions to fast neutron measurements in the atmosphere are outlined. The results of a calculation to determine the production, distribution and final disappearance of atmospheric neutrons over the entire spectrum are presented. An attempt is made to answer questions that relate to processes such as neutron escape from the atmosphere and C-14 production. In addition, since variations of secondary neutrons can be related to variations in the primary radiation, comment on the modulation of both radiation components is made.

  19. Modeling of hydrogen-air diffusion flame

    NASA Technical Reports Server (NTRS)

    Isaac, Kakkattukuzhy

    1988-01-01

    The present research objective is to determine the effects of contaminants on extinction limits of simple, well defined, counterflow Hydrogen 2-air diffusion flames, with combustion at 1 atmosphere. Results of extinction studies and other flame characterizations, with appropriate mechanistic modeling (presently underway), will be used to rationalize the observed effects of contamination over a reasonably wide range of diffusion flame conditions. The knowledge gained should help efforts to anticipate the effects of contaminants on combustion processes in Hydrogen 2-fueled scramjets.

  20. Hydrogen detector

    DOEpatents

    Kanegae, Naomichi; Ikemoto, Ichiro

    1980-01-01

    A hydrogen detector of the type in which the interior of the detector is partitioned by a metal membrane into a fluid section and a vacuum section. Two units of the metal membrane are provided and vacuum pipes are provided independently in connection to the respective units of the metal membrane. One of the vacuum pipes is connected to a vacuum gauge for static equilibrium operation while the other vacuum pipe is connected to an ion pump or a set of an ion pump and a vacuum gauge both designed for dynamic equilibrium operation.

  1. Lunar atmospheric composition experiment

    NASA Technical Reports Server (NTRS)

    Hoffman, J. H.

    1975-01-01

    Apollo 17 carried a miniature mass spectrometer, called the Lunar Atmospheric Composition Experiment (LACE), to the moon as part of the Apollo Lunar Surface Experiments Package (ALSEP) to study the composition and variations in the lunar atmosphere. The instrument was successfully deployed in the Taurus-Littrow Valley with its entrance aperture oriented upward to intercept and measure the downward flux of gases at the lunar surface. During the ten lunations that the LACE operated, it produced a large base of data on the lunar atmosphere, mainly collected at night time. It was found that thermal escape is the most rapid loss mechanism for hydrogen and helium. For heavier gases, photoionization followed by acceleration through the solar wind electric field accounted for most of the loss. The dominant gases on the moosn were argon and helium, and models formed for their distribution are described in detail. It is concluded that most of the helium in the lunar atmosphere is of solar wind origin, and that there also exist very small amounts of methane, ammonia, and carbon dioxide.

  2. The Atmosphere.

    ERIC Educational Resources Information Center

    Ingersoll, Andrew P.

    1983-01-01

    The composition and dynamics of the earth's atmosphere are discussed, considering the atmosphere's role in distributing the energy of solar radiation received by the earth. Models of this activity which help to explain climates of the past and predict those of the future are also considered. (JN)

  3. Hydrogen: the future energy carrier.

    PubMed

    Züttel, Andreas; Remhof, Arndt; Borgschulte, Andreas; Friedrichs, Oliver

    2010-07-28

    Since the beginning of the twenty-first century the limitations of the fossil age with regard to the continuing growth of energy demand, the peaking mining rate of oil, the growing impact of CO2 emissions on the environment and the dependency of the economy in the industrialized world on the availability of fossil fuels became very obvious. A major change in the energy economy from fossil energy carriers to renewable energy fluxes is necessary. The main challenge is to efficiently convert renewable energy into electricity and the storage of electricity or the production of a synthetic fuel. Hydrogen is produced from water by electricity through an electrolyser. The storage of hydrogen in its molecular or atomic form is a materials challenge. Some hydrides are known to exhibit a hydrogen density comparable to oil; however, these hydrides require a sophisticated storage system. The system energy density is significantly smaller than the energy density of fossil fuels. An interesting alternative to the direct storage of hydrogen are synthetic hydrocarbons produced from hydrogen and CO2 extracted from the atmosphere. They are CO2 neutral and stored like fossil fuels. Conventional combustion engines and turbines can be used in order to convert the stored energy into work and heat.

  4. Urban atmospheres.

    PubMed

    Gandy, Matthew

    2017-07-01

    What is an urban atmosphere? How can we differentiate an 'atmosphere' from other facets of urban consciousness and experience? This essay explores some of the wider cultural, political, and philosophical connotations of atmospheres as a focal point for critical reflections on space and subjectivity. The idea of an 'affective atmosphere' as a distinctive kind of mood or shared corporeal phenomenon is considered in relation to recent developments in phenomenology, extended conceptions of agency, and new understandings of materialism. The essay draws in particular on the changing characteristics of air and light to reflect on different forms of sensory experience and their wider cultural and political connotations. The argument highlights some of the tensions and anomalies that permeate contemporary understandings of urban atmospheres.

  5. Process for recovering evolved hydrogen enriched with at least one heavy hydrogen isotope

    DOEpatents

    Tanaka, John; Reilly, Jr., James J.

    1978-01-01

    This invention relates to a separation means and method for enriching a hydrogen atmosphere with at least one heavy hydrogen isotope by using a solid titaniun alloy hydride. To this end, the titanium alloy hydride containing at least one metal selected from the group consisting of vanadium, chromium, manganese, molybdenum, iron, cobalt and nickel is contacted with a circulating gaseous flow of hydrogen containing at least one heavy hydrogen isotope at a temperature in the range of -20.degree. to +40.degree. C and at a pressure above the dissociation pressure of the hydrided alloy selectively to concentrate at least one of the isotopes of hydrogen in the hydrided metal alloy. The contacting is continued until equilibrium is reached, and then the gaseous flow is isolated while the temperature and pressure of the enriched hydride remain undisturbed selectively to isolate the hydride. Thereafter, the enriched hydrogen is selectively recovered in accordance with the separation factor (S.F.) of the alloy hydride employed.

  6. Development of an electrochemical hydrogen separator

    SciTech Connect

    Abens, S.; Fruchtman, J.; Kush, A.

    1992-01-01

    The electrochemical hydrogen separator (EHS), under development at ERC, has several attractive features: The operating temperature (150[degree]C--200[degree]C) is higher than those associated with the currently available devices and is compatible with the low temperature shift reactors. The EHS can operate at atmospheric as well as elevated pressures and the product H[sub 2] is available at the feed stream pressure. High hydrogen recovery factor: 90% H[sub 2] recovery from feed streams containing less than 10% hydrogen is feasible. High hydrogen purity: The product H[sub 2] purity is >99% (dry basis) and is virtually independent of H[sub 2] concentration in the feedmore » gas. The process is continuous. Low energy cost: Depending upon the operating conditions, the energy requirement varies between 2 to 6 kWh/1000 SCF of recovered hydrogen.« less

  7. Development of an electrochemical hydrogen separator

    SciTech Connect

    Abens, S.; Fruchtman, J.; Kush, A.

    1992-11-01

    The electrochemical hydrogen separator (EHS), under development at ERC, has several attractive features: The operating temperature (150{degree}C--200{degree}C) is higher than those associated with the currently available devices and is compatible with the low temperature shift reactors. The EHS can operate at atmospheric as well as elevated pressures and the product H{sub 2} is available at the feed stream pressure. High hydrogen recovery factor: 90% H{sub 2} recovery from feed streams containing less than 10% hydrogen is feasible. High hydrogen purity: The product H{sub 2} purity is >99% (dry basis) and is virtually independent of H{sub 2} concentration in the feedmore » gas. The process is continuous. Low energy cost: Depending upon the operating conditions, the energy requirement varies between 2 to 6 kWh/1000 SCF of recovered hydrogen.« less

  8. Hydrogen production at hydro-power plants

    NASA Astrophysics Data System (ADS)

    Tarnay, D. S.

    A tentative design for hydrogen-producing installations at hydropower facilities is discussed from technological, economic and applications viewpoints. The plants would use alternating current to electrolyze purified river water. The hydrogen would be stored in gas or liquid form and oxygen would be sold or vented to the atmosphere. The hydrogen could later be burned in a turbine generator for meeting peak loads, either in closed or open cycle systems. The concept would allow large hydroelectric plants to function in both base- and peak-load modes, thus increasing the hydraulic utilization of the plant and the capacity factor to a projected 0.90. Electrolyzer efficiencies ranging from 0.85-0.90 have been demonstrated. Excess hydrogen can be sold for other purposes or, eventually, as domestic and industrial fuel, at prices competitive with current industrial hydrogen.

  9. Mechanochemical hydrogenation of coal

    DOEpatents

    Yang, Ralph T.; Smol, Robert; Farber, Gerald; Naphtali, Leonard M.

    1981-01-01

    Hydrogenation of coal is improved through the use of a mechanical force to reduce the size of the particulate coal simultaneously with the introduction of gaseous hydrogen, or other hydrogen donor composition. Such hydrogen in the presence of elemental tin during this one-step size reduction-hydrogenation further improves the yield of the liquid hydrocarbon product.

  10. Hydrogen iodide decomposition

    DOEpatents

    O'Keefe, Dennis R.; Norman, John H.

    1983-01-01

    Liquid hydrogen iodide is decomposed to form hydrogen and iodine in the presence of water using a soluble catalyst. Decomposition is carried out at a temperature between about 350.degree. K. and about 525.degree. K. and at a corresponding pressure between about 25 and about 300 atmospheres in the presence of an aqueous solution which acts as a carrier for the homogeneous catalyst. Various halides of the platinum group metals, particularly Pd, Rh and Pt, are used, particularly the chlorides and iodides which exhibit good solubility. After separation of the H.sub.2, the stream from the decomposer is countercurrently extracted with nearly dry HI to remove I.sub.2. The wet phase contains most of the catalyst and is recycled directly to the decomposition step. The catalyst in the remaining almost dry HI-I.sub.2 phase is then extracted into a wet phase which is also recycled. The catalyst-free HI-I.sub.2 phase is finally distilled to separate the HI and I.sub.2. The HI is recycled to the reactor; the I.sub.2 is returned to a reactor operating in accordance with the Bunsen equation to create more HI.

  11. Hydrogen Chemical Configuration and Thermal Stability in Tungsten Disulfide Nanoparticles Exposed to Hydrogen Plasma.

    PubMed

    Laikhtman, Alex; Makrinich, Gennady; Sezen, Meltem; Yildizhan, Melike Mercan; Martinez, Jose I; Dinescu, Doru; Prodana, Mariana; Enachescu, Marius; Alonso, Julio A; Zak, Alla

    2017-06-01

    The chemical configuration and interaction mechanism of hydrogen adsorbed in inorganic nanoparticles of WS 2 are investigated. Our recent approaches of using hydrogen activated by either microwave or radiofrequency plasma dramatically increased the efficiency of its adsorption on the nanoparticles surface. In the current work we make an emphasis on elucidation of the chemical configuration of the adsorbed hydrogen. This configuration is of primary importance as it affects its adsorption stability and possibility of release. To get insight on the chemical configuration, we combined the experimental analysis methods with theoretical modeling based on the density functional theory (DFT). Micro-Raman spectroscopy was used as a primary tool to elucidate chemical bonding of hydrogen and to distinguish between chemi- and physisorption. Hydrogen adsorbed in molecular form (H 2 ) was clearly identified in all the plasma-hydrogenated WS 2 nanoparticles samples. It was shown that the adsorbed hydrogen is generally stable under high vacuum conditions at room temperature, which implies its stability at the ambient atmosphere. A DFT model was developed to simulate the adsorption of hydrogen in the WS 2 nanoparticles. This model considers various adsorption sites and identifies the preferential locations of the adsorbed hydrogen in several WS 2 structures, demonstrating good concordance between theory and experiment and providing tools for optimizing of hydrogen exposure conditions and the type of substrate materials.

  12. Non-thermal hydrogen atoms in the terrestrial upper thermosphere.

    PubMed

    Qin, Jianqi; Waldrop, Lara

    2016-12-06

    Model predictions of the distribution and dynamical transport of hydrogen atoms in the terrestrial atmosphere have long-standing discrepancies with ultraviolet remote sensing measurements, indicating likely deficiencies in conventional theories regarding this crucial atmospheric constituent. Here we report the existence of non-thermal hydrogen atoms that are much hotter than the ambient oxygen atoms in the upper thermosphere. Analysis of satellite measurements indicates that the upper thermospheric hydrogen temperature, more precisely the mean kinetic energy of the atomic hydrogen population, increases significantly with declining solar activity, contrary to contemporary understanding of thermospheric behaviour. The existence of hot hydrogen atoms in the upper thermosphere, which is the key to reconciling model predictions and observations, is likely a consequence of low atomic oxygen density leading to incomplete collisional thermalization of the hydrogen population following its kinetic energization through interactions with hot atomic or ionized constituents in the ionosphere, plasmasphere or magnetosphere.

  13. Atmospheric chemistry

    NASA Astrophysics Data System (ADS)

    Mitra, A. P.

    1990-12-01

    The important elements of atmospheric chemistry - neutral and ionic - including those that have been considered in recent years in connection with ozone depletion and greenhouse molecules, but spanning the entire atmospheric environment from the surface to 1000 km are reviewed. The basic approach has been to indicate how the nature of chemical reactions changes as we go from the surface to the stratosphere through the mesosphere into the thermosphere.

  14. Solar flare model atmospheres

    NASA Technical Reports Server (NTRS)

    Hawley, Suzanne L.; Fisher, George H.

    1993-01-01

    Solar flare model atmospheres computed under the assumption of energetic equilibrium in the chromosphere are presented. The models use a static, one-dimensional plane parallel geometry and are designed within a physically self-consistent coronal loop. Assumed flare heating mechanisms include collisions from a flux of non-thermal electrons and x-ray heating of the chromosphere by the corona. The heating by energetic electrons accounts explicitly for variations of the ionized fraction with depth in the atmosphere. X-ray heating of the chromosphere by the corona incorporates a flare loop geometry by approximating distant portions of the loop with a series of point sources, while treating the loop leg closest to the chromospheric footpoint in the plane-parallel approximation. Coronal flare heating leads to increased heat conduction, chromospheric evaporation and subsequent changes in coronal pressure; these effects are included self-consistently in the models. Cooling in the chromosphere is computed in detail for the important optically thick HI, CaII and MgII transitions using the non-LTE prescription in the program MULTI. Hydrogen ionization rates from x-ray photo-ionization and collisional ionization by non-thermal electrons are included explicitly in the rate equations. The models are computed in the 'impulsive' and 'equilibrium' limits, and in a set of intermediate 'evolving' states. The impulsive atmospheres have the density distribution frozen in pre-flare configuration, while the equilibrium models assume the entire atmosphere is in hydrostatic and energetic equilibrium. The evolving atmospheres represent intermediate stages where hydrostatic equilibrium has been established in the chromosphere and corona, but the corona is not yet in energetic equilibrium with the flare heating source. Thus, for example, chromospheric evaporation is still in the process of occurring.

  15. Hydrogen embrittlement in nickel-hydrogen cells

    NASA Technical Reports Server (NTRS)

    Gross, Sidney

    1989-01-01

    It was long known that many strong metals can become weakened and brittle as the result of the accumulation of hydrogen within the metal. When the metal is stretched, it does not show normal ductile properties, but fractures prematurely. This problem can occur as the result of a hydrogen evolution reaction such as corrosion or electroplating, or due to hydrogen in the environment at the metal surface. High strength alloys such as steels are especially susceptible to hydrogen embrittlement. Nickel-hydrogen cells commonly use Inconel 718 alloy for the pressure container, and this also is susceptible to hydrogen embrittlement. Metals differ in their susceptibility to embrittlement. Hydrogen embrittlement in nickel-hydrogen cells is analyzed and the reasons why it may or may not occur are discussed. Although Inconel 718 can display hydrogen embrittlement, experience has not identified any problem with nickel-hydrogen cells. No hydrogen embrittlement problem is expected with the 718 alloy pressure container used in nickel-hydrogen cells.

  16. Evolution of the atmosphere.

    PubMed

    Nunn, J F

    1998-01-01

    Planetary atmospheres depend fundamentally upon their geochemical inventory, temperature and the ability of their gravitational field to retain gases. In the case of Earth and other inner planets, early outgassing released mainly carbon dioxide and water vapour. The secondary veneer of comets and meteorites added further volatiles. Photodissociation caused secondary changes, including the production of traces of oxygen from water. Earth's gravity cannot retain light gases, including hydrogen. but retains oxygen. Water vapour generally does not pass the cold trap at the stratopause. In the archaean, early evolution of life, probably in hydrothermal vents, and the subsequent development of photosynthesis in surface waters, produced oxygen, at 3500 Ma or even earlier, becoming a significant component of the atmosphere from about 2000 Ma. Thereafter banded iron formations became rare, and iron was deposited in oxidized red beds. Atmospheric levels of carbon dioxide and oxygen have varied during the Phanerozoic: major changes may have caused extinctions. particularly the Permian/Triassic. The declining greenhouse effect due to the long-term decrease in carbon dioxide has largely offset increasing solar luminosity, and changes in carbon dioxide levels relate strongly to cycles of glaciation.

  17. Atmospheric Photochemistry

    NASA Technical Reports Server (NTRS)

    Massey, Harrie; Potter, A. E.

    1961-01-01

    The upper atmosphere offers a vast photochemical laboratory free from solid surfaces, so all reactions take place in the gaseous phase. At 30 km altitude the pressure has fallen to about one-hundredth of that at ground level, and we shall, rather arbitrarily, regard the upper atmosphere as beginning at that height. By a little less than 100 km the pressure has fallen to 10(exp -3) mm Hg and is decreasing by a power of ten for every 15 km increase in altitude. Essentially we are concerned then with the photochemistry of a nitrogen-oxygen mixture under low-pressure conditions in which photo-ionization, as well as photodissociation, plays an important part. Account must also be taken of the presence of rare constituents, such as water vapour and its decomposition products, including particularly hydroxyl, oxides of carbon, methane and, strangely enough, sodium, lithium and calcium. Many curious and unfamiliar reactions occur in the upper atmosphere. Some of them are luminescent, causing the atmosphere to emit a dim light called the airglow. Others, between gaseous ions and neutral molecules, are almost a complete mystery at this time. Similar interesting phenomena must occur in other planetary atmospheres, and they might be predicted if sufficient chemical information were available.

  18. Atmospheric Structure

    NASA Technical Reports Server (NTRS)

    2007-01-01

    This is a composite of several images taken in several colors by the New Horizons Multispectral Visual Imaging Camera, or MVIC. It illustrates the remarkable diversity of structures in Jupiter's atmosphere, in colors similar to what someone 'riding' on New Horizons would see. It was taken near the terminator, the boundary between day and night, and shows relatively small-scale, turbulent, whirlpool-like structures near the south pole of the planet. The dark 'holes' in this region are actually places where there is very little cloud cover, so sunlight is not reflected back to the camera. Moving toward the equator, the atmospheric structures become more elongated in an east-west direction, taking on the familiar pattern of dark 'belts' and light 'zones.' At the equator itself, a herringbone pattern of clouds known as 'mesoscale waves' is apparent, especially near the edge of the terminator where the glancing angle of sunlight emphasizes the alternating dark and light North-South stripes. The energy to form these waves comes from deeper in Jupiter's atmosphere.

    This picture provides a vivid illustration that Jupiter's atmosphere has more color contrast than any other atmosphere in the solar system, including Earth's. Data obtained from these and other New Horizons images taken during the encounter will provide valuable insight into the processes occurring on this gas giant.

  19. Hydrogen Annealing Of Single-Crystal Superalloys

    NASA Technical Reports Server (NTRS)

    Smialek, James L.; Schaeffer, John C.; Murphy, Wendy

    1995-01-01

    Annealing at temperature equal to or greater than 2,200 degrees F in atmosphere of hydrogen found to increase ability of single-crystal superalloys to resist oxidation when subsequently exposed to oxidizing atmospheres at temperatures almost as high. Supperalloys in question are principal constituents of hot-stage airfoils (blades) in aircraft and ground-based turbine engines; also used in other high-temperature applications like chemical-processing plants, coal-gasification plants, petrochemical refineries, and boilers. Hydrogen anneal provides resistance to oxidation without decreasing fatigue strength and without need for coating or reactive sulfur-gettering constituents. In comparison with coating, hydrogen annealing costs less. Benefits extend to stainless steels, nickel/chromium, and nickel-base alloys, subject to same scale-adhesion and oxidation-resistance considerations, except that scale is chromia instead of alumina.

  20. Atmospheric dynamics

    NASA Technical Reports Server (NTRS)

    Lindzen, Richard S.; Farrell, Brian

    1987-01-01

    The paper presents an overview of U.S. contributions in the period of 1983-1986, to the analysis and study of the atmosphere's motion and of the role of this motion in the thermodynamics and chemistry of the atmosphere. Special attention is given to the linear and quasi-linear studies of the dynamics of atmospheric disturbances; studies of the wave breaking phenomenon; and investigations of various long-lived features, ranging from climatological stationary waves to long-period oscillations in the tropics. Consideration is also given to diagnostics for the interactions among disturbances and the mean flow, nontraditional approaches to instability and disturbance growth, and dynamical systems and multiple equilibria.

  1. Urban atmospheres

    PubMed Central

    Gandy, Matthew

    2017-01-01

    What is an urban atmosphere? How can we differentiate an ‘atmosphere’ from other facets of urban consciousness and experience? This essay explores some of the wider cultural, political, and philosophical connotations of atmospheres as a focal point for critical reflections on space and subjectivity. The idea of an ‘affective atmosphere’ as a distinctive kind of mood or shared corporeal phenomenon is considered in relation to recent developments in phenomenology, extended conceptions of agency, and new understandings of materialism. The essay draws in particular on the changing characteristics of air and light to reflect on different forms of sensory experience and their wider cultural and political connotations. The argument highlights some of the tensions and anomalies that permeate contemporary understandings of urban atmospheres. PMID:29278257

  2. Hydrogen permeation, diffusion and solubility in IN-100 and Waspaloy

    NASA Technical Reports Server (NTRS)

    Khan, A. S.; Peterson, D. T.

    1990-01-01

    An attempt has been made to determine the permeation rate of hydrogen in IN-100 and Waspaloy by determining the evolution rate of hydrogen from a closed capsule of the test materials. Enclosed vanadium hydride was the source of hydrogen in the capsule. The presentation discusses the treatment of data and assesses the validity of the techniques in permeation measurement. In addition to permeation experiments, the solubility and diffusion of hydrogen in IN-100 and Waspaloy were also determined. For hydrogen diffusion in Waspaloy, Delta H was 38.5 kJ and D(0) was 0.0026 sq cm/sec. For IN-100, Delta H was 68.2 kJ and D(0) was 0.059 sq cm /sec. Both IN-100 and Waspaloy exhibited limited solubility of hydrogen at pressures up to 340 atmospheres hydrogen.

  3. Submarine atmospheres.

    PubMed

    Knight, D R; Tappan, D V; Bowman, J S; O'Neill, H J; Gordon, S M

    1989-12-01

    Nuclear submariners live and work in an atmosphere composed of approximately 80% naturally occurring nitrogen, 19% oxygen (manufactured aboard ship), and a complex mixture of inorganic and organic contaminants. The concentrations of contaminants exist as a balance between the rates of production from human and operational activities and the rate of removal by engineering systems. The biological effects of inorganic gases, particularly carbon dioxide, have been extensively studied. Investigators are now attempting to define the composition and concentration of volatile organic compounds that accumulate during 90-day submergences. Medical studies have not conclusively shown that crewmembers incur adverse health effects from continuous exposures to the sealed atmospheres of nuclear submarines.

  4. Composition for absorbing hydrogen

    DOEpatents

    Heung, L.K.; Wicks, G.G.; Enz, G.L.

    1995-05-02

    A hydrogen absorbing composition is described. The composition comprises a porous glass matrix, made by a sol-gel process, having a hydrogen-absorbing material dispersed throughout the matrix. A sol, made from tetraethyl orthosilicate, is mixed with a hydrogen-absorbing material and solidified to form a porous glass matrix with the hydrogen-absorbing material dispersed uniformly throughout the matrix. The glass matrix has pores large enough to allow gases having hydrogen to pass through the matrix, yet small enough to hold the particles dispersed within the matrix so that the hydrogen-absorbing particles are not released during repeated hydrogen absorption/desorption cycles.

  5. Composition for absorbing hydrogen

    DOEpatents

    Heung, Leung K.; Wicks, George G.; Enz, Glenn L.

    1995-01-01

    A hydrogen absorbing composition. The composition comprises a porous glass matrix, made by a sol-gel process, having a hydrogen-absorbing material dispersed throughout the matrix. A sol, made from tetraethyl orthosilicate, is mixed with a hydrogen-absorbing material and solidified to form a porous glass matrix with the hydrogen-absorbing material dispersed uniformly throughout the matrix. The glass matrix has pores large enough to allow gases having hydrogen to pass through the matrix, yet small enough to hold the particles dispersed within the matrix so that the hydrogen-absorbing particles are not released during repeated hydrogen absorption/desorption cycles.

  6. Vanadium diaphragm electrode serves as hydrogen diffuser in lithium hydride cell

    NASA Technical Reports Server (NTRS)

    Crouthamel, C. E.; Heinrich, R. R.; Johnson, C. E.

    1967-01-01

    Lithium hydride cell uses vanadium diaphragm electrode as a hydrogen diffuser. Vanadium is high in hydrogen gas solubility and permeability, is least sensitive to adverse surface effects, maintains good mechanical strength in hydrogen atmospheres, and appears to be compatible with all alkali-halide electrolytes and lithium metals.

  7. Thermodynamic properties of hydrogen-helium plasmas.

    NASA Technical Reports Server (NTRS)

    Nelson, H. F.

    1972-01-01

    Calculation of the thermodynamic properties of an atomic hydrogen-helium plasma for postulated conditions present in a stagnation shock layer of a spacecraft entering the atmosphere of Jupiter. These properties can be used to evaluate transport properties, to calculate convective heating, and to investigate nonequilibrium behavior. The calculations have been made for temperatures from 10,000 to 100,000 K, densities of 10 to the minus 7th and .00001 g cu cm, and three plasma compositions: pure hydrogen, 50% hydrogen/50% helium, and pure helium. The shock layer plasma consists of electrons, protons, atomic hydrogen, atomic helium, singly ionized helium, and doubly atomized helium. The thermodynamic properties which have been investigated are: pressure, average molecular weight, internal energy, enthalpy, entropy, specific heat, and isentropic speed of sound. A consistent model was used for the reduction of the ionization potential in the calculation of the partition functions.

  8. Earth's earliest atmospheres.

    PubMed

    Zahnle, Kevin; Schaefer, Laura; Fegley, Bruce

    2010-10-01

    Earth is the one known example of an inhabited planet and to current knowledge the likeliest site of the one known origin of life. Here we discuss the origin of Earth's atmosphere and ocean and some of the environmental conditions of the early Earth as they may relate to the origin of life. A key punctuating event in the narrative is the Moon-forming impact, partly because it made Earth for a short time absolutely uninhabitable, and partly because it sets the boundary conditions for Earth's subsequent evolution. If life began on Earth, as opposed to having migrated here, it would have done so after the Moon-forming impact. What took place before the Moon formed determined the bulk properties of the Earth and probably determined the overall compositions and sizes of its atmospheres and oceans. What took place afterward animated these materials. One interesting consequence of the Moon-forming impact is that the mantle is devolatized, so that the volatiles subsequently fell out in a kind of condensation sequence. This ensures that the volatiles were concentrated toward the surface so that, for example, the oceans were likely salty from the start. We also point out that an atmosphere generated by impact degassing would tend to have a composition reflective of the impacting bodies (rather than the mantle), and these are almost without exception strongly reducing and volatile-rich. A consequence is that, although CO- or methane-rich atmospheres are not necessarily stable as steady states, they are quite likely to have existed as long-lived transients, many times. With CO comes abundant chemical energy in a metastable package, and with methane comes hydrogen cyanide and ammonia as important albeit less abundant gases.

  9. Atmospheric humidity

    USDA-ARS?s Scientific Manuscript database

    Water vapor plays a critical role in earth's atmosphere. It helps to maintain a habitable surface temperature through absorption of outgoing longwave radiation, and it transfers trmendous amounts of energy from the tropics toward the poles by absorbing latent heat during evaporation and subsequently...

  10. Jupiter's Atmosphere: Its Structure and Composition.

    PubMed

    Greenspan, J A; Owen, T

    1967-06-16

    Recent laboratory and observational data support the hypothesis that the composition of Jupiter's atmosphere is consistent with the relative abundances of the elements found in the sun. A model based on this assumption provides a reasonable interpretation of abundances of hydrogen and other gases obtained from studies of various regions of the planet's spectrum. Two presently unidentified absorptions may be caused by organic molecules in the Jovian atmosphere.

  11. A Few Facts about Hydrogen [and] Hydrogen Bibliography.

    ERIC Educational Resources Information Center

    Hinds, H. Roger

    Divided into two sections, this publication presents facts about and the characteristics of hydrogen and a bibliography on hydrogen. The first section lists nine facts on what hydrogen is, four on where hydrogen is found, nine on how hydrogen is used, nine on how hydrogen can be used, and 14 on how hydrogen is made. Also included are nine…

  12. Hydrogen Escape from early Earth and Mars

    NASA Astrophysics Data System (ADS)

    Zugger, M. E.; Ramirez, R. M.; Kasting, J. F.

    2012-12-01

    A controversy regarding hydrodynamic escape rates arose when Tian et al. (2005) published transonic escape rates for an atmosphere composed of pure H2. Tian et al. concluded that the hydrogen escape rate from early Earth would have been a factor of 20 or more slower than the diffusion limit, even if the solar EUV (extreme ultraviolet) flux was enhanced by a factor of 5 relative to today. This conclusion was challenged by Catling (2006), who pointed out that solar EUV fluxes could have been much higher than this so that plenty of energy should have been available to power escape. This controversy has remained unresolved to date. Hydrogen escape from early Mars is also of interest. As discussed in this session in a complementary paper by Ramirez et al., collision-induced absorption by molecular hydrogen could have helped to warm early Mars, perhaps explaining the formation of valleys and valley networks. Ramirez et al. have shown that a mixture of 90% CO2 and 10% H2 is capable raising early Mars' surface temperature above the freezing point of water, for surface pressures exceeding ~3 bar. However, we need to understand whether H2 mixing ratios of 10% are physically plausible. The H2 partial pressure in Mars' early atmosphere would have been determined by the balance between volcanic outgassing and escape to space. The 10% mixing ratio is high compared to the value of ~10-3 typically assumed for early Earth. But Mars' early atmosphere may have been more reduced than Earth's (Wadwha, 2001); if the hydrogen escape rate on Mars was also slower than on Earth, then additional increases in atmospheric hydrogen concentration are possible. To answer these questions about the early atmospheres of Earth and Mars, we have modified an existing model of hydrodynamic escape, developed by F. Tian, J. Kasting, and others, to converge for atmospheres with a wide range of hydrogen mixing ratios. The model finds subsonic solutions to the hydrodynamic equations; these can be shown to

  13. A hydrogen refill for cellular phone

    NASA Astrophysics Data System (ADS)

    Prosini, Pier Paolo; Gislon, Paola

    A device has been designed to generate hydrogen for a fuel cell powered cellular phone. The device is based on the chemical reaction between NaBH 4 and hydrochloric/water solution to satisfy the hydrogen request at room temperature and pressure. The operation mechanism and controlling method is based on the Kipp's gas generating apparatus. A prototype has been built and tested to evaluate the optimum salt/acid and acid/solution ratios and check the hydrogen mass flow rates upon operation and the pressure variation in stand-by condition. The system works delivering hydrogen flows ranging between 0 and 10 ml min -1. In a typical test the hydrogen flow was set to 5 ml min -1 to match a 1 W power fuel cell. The working pressure was slightly higher than the atmospheric one. The hydrogen capacity was as high as 2.5% (w/w). By converting this amount of hydrogen in electricity by a fuel cell working at 0.8 V it is possible to achieve a system energy density of about 720 Wh kg -1, four times larger than commercial high energy density lithium-ion batteries.

  14. Investigating Elevated Concentrations of Hydrogen in the LAX region

    NASA Astrophysics Data System (ADS)

    Rund, P.; Hughes, S.; Blake, D. R.

    2017-12-01

    The growing interest in hydrogen (H2) fuel cell vehicles has created a need to study the atmospheric H2 budget. While there is resounding agreement that hydrogen would escape into the atmosphere due to fuel transport/storage processes, there is disagreement over the amount that would be leaked in a hydrogen fuel economy. Leakage rate estimates range from 2% to 10% for total hydrogen production and transport. A hydrogen based energy infrastructure seems a viable clean alternative to oil because, theoretically, the only waste products are H2O and heat. However, hydrogen leads to the formation of water vapor, polar stratospheric clouds, and a decrease in stratospheric temperatures, which contribute to the depletion of stratospheric ozone. Whole air samples (WAS) collected aboard the NASA Sherpa C-23 during the Student Airborne Research Program (SARP) showed elevated concentrations of hydrogen near LAX (950 ± 110 ppbv) compared to global average concentrations of 560 ± 20 ppbv. Trace gas analysis along with wind trajectories obtained with the NOAA HySPLIT models indicate that the source of elevated mixing ratios was leakage from H2 fuel stations in the surrounding areas. Correlation and ratio analyses eliminate the potential for common photochemical sources of H2 in the LAX area. This project could elucidate new and potential factors that contribute to the global atmospheric hydrogen budget.

  15. A novel hydride phase in hydrogen charged Ti3Al

    NASA Technical Reports Server (NTRS)

    Schwartz, D. S.; Lederich, R. J.; Sastry, S. M. L.; Yelon, W. B.; Berliner, R. R.

    1991-01-01

    The effect of internal hydrogen on the microstructural modification of Ti3Al (alpha-2) compound was studied by large-angle neutron scattering and TEM. Ti-25 at. pct Al (Ti3Al) specimens were exposed to gaseous hydrogen atmosphere at 600 C that resulted in internal hydrogen concentration of 2000 ppm. The hydrogen-charged alloy consisted of a mixture of alpha-2 phase and a novel Ti3AlH phase with the E2(1), (Pm3m) crystal structure. The lattice parameters and atomic arrangement of the Ti3AlH phase were determined.

  16. Hydrogen energy systems studies

    SciTech Connect

    Ogden, J.M.; Kreutz, T.G.; Steinbugler, M.

    1996-10-01

    In this report the authors describe results from technical and economic assessments carried out during the past year with support from the USDOE Hydrogen R&D Program. (1) Assessment of technologies for small scale production of hydrogen from natural gas. Because of the cost and logistics of transporting and storing hydrogen, it may be preferable to produce hydrogen at the point of use from more readily available energy carriers such as natural gas or electricity. In this task the authors assess near term technologies for producing hydrogen from natural gas at small scale including steam reforming, partial oxidation and autothermal reforming.more » (2) Case study of developing a hydrogen vehicle refueling infrastructure in Southern California. Many analysts suggest that the first widespread use of hydrogen energy is likely to be in zero emission vehicles in Southern California. Several hundred thousand zero emission automobiles are projected for the Los Angeles Basin alone by 2010, if mandated levels are implemented. Assuming that hydrogen vehicles capture a significant fraction of this market, a large demand for hydrogen fuel could evolve over the next few decades. Refueling a large number of hydrogen vehicles poses significant challenges. In this task the authors assess near term options for producing and delivering gaseous hydrogen transportation fuel to users in Southern California including: (1) hydrogen produced from natural gas in a large, centralized steam reforming plant, and delivered to refueling stations via liquid hydrogen truck or small scale hydrogen gas pipeline, (2) hydrogen produced at the refueling station via small scale steam reforming of natural gas, (3) hydrogen produced via small scale electrolysis at the refueling station, and (4) hydrogen from low cost chemical industry sources (e.g. excess capacity in refineries which have recently upgraded their hydrogen production capacity, etc.).« less

  17. Concentration of Hydrogen Peroxide

    NASA Technical Reports Server (NTRS)

    Parrish, Clyde F. (Inventor)

    2006-01-01

    Methods for concentrating hydrogen peroxide solutions have been described. The methods utilize a polymeric membrane separating a hydrogen peroxide solution from a sweep gas or permeate. The membrane is selective to the permeability of water over the permeability of hydrogen peroxide, thereby facilitating the concentration of the hydrogen peroxide solution through the transport of water through the membrane to the permeate. By utilizing methods in accordance with the invention, hydrogen peroxide solutions of up to 85% by volume or higher may be generated at a point of use without storing substantial quantities of the highly concentrated solutions and without requiring temperatures that would produce explosive mixtures of hydrogen peroxide vapors.

  18. The helium mass fraction in Jupiter's atmosphere.

    PubMed

    von Zahn, U; Hunten, D M

    1996-05-10

    On 7 December 1995, the NASA Galileo probe provided in situ measurements of the helium abundance in the atmosphere of Jupiter. A Jamin interferometer measured the refractive index of the jovian atmosphere in the pressure region from 2 to 14 bars. These measurements indicate that the atmospheric helium mole fraction is 0.136 +/- 0.004. The corresponding helium mass fraction is slightly below the presolar value, which suggests that separation of helium from hydrogen in Jupiter's interior is only in its early stages.

  19. Hydrogen Hotspots on Vesta

    NASA Image and Video Library

    2012-09-20

    This image shows that NASA Dawn mission detected abundances of hydrogen in a wide swath around the equator of the giant asteroid Vesta. The hydrogen probably exists in the form of hydroxyl or water bound to minerals in Vesta surface.

  20. Freezing WISE Hydrogen

    NASA Image and Video Library

    2009-11-12

    A scaffolding structure built around NASA Wide-field Infrared Survey Explorer allows engineers to freeze its hydrogen coolant. The WISE infrared instrument is kept extremely cold by a bottle-like tank filled with frozen hydrogen, called the cryostat.

  1. Hydrogen production by Cyanobacteria

    PubMed Central

    Dutta, Debajyoti; De, Debojyoti; Chaudhuri, Surabhi; Bhattacharya, Sanjoy K

    2005-01-01

    The limited fossil fuel prompts the prospecting of various unconventional energy sources to take over the traditional fossil fuel energy source. In this respect the use of hydrogen gas is an attractive alternate source. Attributed by its numerous advantages including those of environmentally clean, efficiency and renew ability, hydrogen gas is considered to be one of the most desired alternate. Cyanobacteria are highly promising microorganism for hydrogen production. In comparison to the traditional ways of hydrogen production (chemical, photoelectrical), Cyanobacterial hydrogen production is commercially viable. This review highlights the basic biology of cynobacterial hydrogen production, strains involved, large-scale hydrogen production and its future prospects. While integrating the existing knowledge and technology, much future improvement and progress is to be done before hydrogen is accepted as a commercial primary energy source. PMID:16371161

  2. Hydrogen production by Cyanobacteria.

    PubMed

    Dutta, Debajyoti; De, Debojyoti; Chaudhuri, Surabhi; Bhattacharya, Sanjoy K

    2005-12-21

    The limited fossil fuel prompts the prospecting of various unconventional energy sources to take over the traditional fossil fuel energy source. In this respect the use of hydrogen gas is an attractive alternate source. Attributed by its numerous advantages including those of environmentally clean, efficiency and renew ability, hydrogen gas is considered to be one of the most desired alternate. Cyanobacteria are highly promising microorganism for hydrogen production. In comparison to the traditional ways of hydrogen production (chemical, photoelectrical), Cyanobacterial hydrogen production is commercially viable. This review highlights the basic biology of cynobacterial hydrogen production, strains involved, large-scale hydrogen production and its future prospects. While integrating the existing knowledge and technology, much future improvement and progress is to be done before hydrogen is accepted as a commercial primary energy source.

  3. Hydrogen transport membranes

    DOEpatents

    Mundschau, Michael V.

    2005-05-31

    Composite hydrogen transport membranes, which are used for extraction of hydrogen from gas mixtures are provided. Methods are described for supporting metals and metal alloys which have high hydrogen permeability, but which are either too thin to be self supporting, too weak to resist differential pressures across the membrane, or which become embrittled by hydrogen. Support materials are chosen to be lattice matched to the metals and metal alloys. Preferred metals with high permeability for hydrogen include vanadium, niobium, tantalum, zirconium, palladium, and alloys thereof. Hydrogen-permeable membranes include those in which the pores of a porous support matrix are blocked by hydrogen-permeable metals and metal alloys, those in which the pores of a porous metal matrix are blocked with materials which make the membrane impervious to gases other than hydrogen, and cermets fabricated by sintering powders of metals with powders of lattice-matched ceramic.

  4. Center for Hydrogen Storage.

    DOT National Transportation Integrated Search

    2013-06-01

    The main goals of this project were to (1) Establish a Center for Hydrogen Storage Research at Delaware State University for the preparation and characterization of selected complex metal hydrides and the determination their suitability for hydrogen ...

  5. Solar hydrogen generator

    NASA Technical Reports Server (NTRS)

    Sebacher, D. I.; Sabol, A. P. (Inventor)

    1977-01-01

    An apparatus, using solar energy to manufacture hydrogen by dissociating water molecules into hydrogen and oxygen molecules is described. Solar energy is concentrated on a globe containing water thereby heating the water to its dissociation temperature. The globe is pervious to hydrogen molecules permitting them to pass through the globe while being essentially impervious to oxygen molecules. The hydrogen molecules are collected after passing through the globe and the oxygen molecules are removed from the globe.

  6. Cryogenic hydrogen-induced air-liquefaction technologies

    NASA Technical Reports Server (NTRS)

    Escher, William J. D.

    1990-01-01

    Extensive use of a special advanced airbreathing propulsion archives data base, as well as direct contacts with individuals who were active in the field in previous years, a technical assessment of cryogenic hydrogen induced air liquefaction, as a prospective onboard aerospace vehicle process, was performed and documented in 1986. The resulting assessment report is summarized. Technical findings relating the status of air liquefaction technology are presented both as a singular technical area, and also as that of a cluster of collateral technical areas including: Compact lightweight cryogenic heat exchangers; Heat exchanger atmospheric constituents fouling alleviation; Para/ortho hydrogen shift conversion catalysts; Hydrogen turbine expanders, cryogenic air compressors and liquid air pumps; Hydrogen recycling using slush hydrogen as heat sinks; Liquid hydrogen/liquid air rocket type combustion devices; Air Collection and Enrichment System (ACES); and Technically related engine concepts.

  7. Atmospheric Illusion

    NASA Technical Reports Server (NTRS)

    2005-01-01

    Believe it or not, this extreme close-up of Saturn's swirling clouds was acquired from more than one million kilometers (621,370 miles) from the gas giant planet. The rings' image is severely bent by atmospheric refraction as they pass behind the planet.

    The dark region in the rings is the 4,800-kilometer-wide (2,980 mile) Cassini Division.

    The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 25, 2005, at a distance of approximately 1 million kilometers (600,000 miles) from Saturn. The image scale is 6 kilometers (4 miles) per pixel.

  8. Chemistry and evolution of Titan's atmosphere

    NASA Technical Reports Server (NTRS)

    Strobel, D. F.

    1982-01-01

    The chemistry and evolution of Titan's atmosphere are reviewed, in light of the scientific findings from the Voyager mission. It is argued that the present N2 atmosphere may be Titan's initial atmosphere, rather than one photochemically derived from an original NH3 atmosphere. The escape rate of hydrogen from Titan is controlled by photochemical production from hydrocarbons. CH4 is irreversibly converted to less hydrogen-rich hydrocarbons, which over geologic time accumulate on the surface to a layer thickness of about 0.5 km. Magnetospheric electrons interacting with Titan's exosphere may dissociate enough N2 into hot, escaping N atoms to remove about 0.2 of Titan's present atmosphere over geologic time. The energy dissipation of magnetospheric electrons exceeds solar EUV energy deposition in Titan's atmosphere by an order of magnitude, and is the principal driver of nitrogen photochemistry. The environmental conditions in Titan's upper atmosphere are favorable to building up complex molecules, particularly in the north polar cap region.

  9. Sensitive hydrogen leak detector

    DOEpatents

    Myneni, Ganapati Rao

    1999-01-01

    A sensitive hydrogen leak detector system using passivation of a stainless steel vacuum chamber for low hydrogen outgassing, a high compression ratio vacuum system, a getter operating at 77.5 K and a residual gas analyzer as a quantitative hydrogen sensor.

  10. Sensitive hydrogen leak detector

    DOEpatents

    Myneni, G.R.

    1999-08-03

    A sensitive hydrogen leak detector system is described which uses passivation of a stainless steel vacuum chamber for low hydrogen outgassing, a high compression ratio vacuum system, a getter operating at 77.5 K and a residual gas analyzer as a quantitative hydrogen sensor. 1 fig.

  11. Purification of Hydrogen

    DOEpatents

    Newton, A S

    1950-12-05

    Disclosed is a process for purifying hydrogen containing various gaseous impurities by passing the hydrogen over a large surface of uranium metal at a temperature above the decomposition temperature of uranium hydride, and below the decomposition temperature of the compounds formed by the combination of the uranium with the impurities in the hydrogen.

  12. Hydrogenation of passivated contacts

    SciTech Connect

    Nemeth, William; Yuan, Hao-Chih; LaSalvia, Vincenzo

    2018-03-06

    Methods of hydrogenation of passivated contacts using materials having hydrogen impurities are provided. An example method includes applying, to a passivated contact, a layer of a material, the material containing hydrogen impurities. The method further includes subsequently annealing the material and subsequently removing the material from the passivated contact.

  13. Hydrogen from coal

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Hydrogen production from coal by hydrogasification is described. The process involves the solubilization of coal to form coal liquids, which are hydrogasified to produce synthetic pipeline gas; steam reforming this synthetic gas by a nuclear heat source produces hydrogen. A description is given of the hydrogen plant, its performance, and its effect on the environment.

  14. Liquid metal hydrogen barriers

    DOEpatents

    Grover, George M.; Frank, Thurman G.; Keddy, Edward S.

    1976-01-01

    Hydrogen barriers which comprise liquid metals in which the solubility of hydrogen is low and which have good thermal conductivities at operating temperatures of interest. Such barriers are useful in nuclear fuel elements containing a metal hydride moderator which has a substantial hydrogen dissociation pressure at reactor operating temperatures.

  15. Flash hydrogenation of coal

    DOEpatents

    Manowitz, Bernard; Steinberg, Meyer; Sheehan, Thomas V.; Winsche, Warren E.; Raseman, Chad J.

    1976-01-01

    A process for the hydrogenation of coal comprising the contacting of powdered coal with hydrogen in a rotating fluidized bed reactor. A rotating fluidized bed reactor suitable for use in this process is also disclosed. The coal residence time in the reactor is limited to less than 5 seconds while the hydrogen contact time is not in excess of 0.2 seconds.

  16. Hydrogen donors in α-Al2O3

    NASA Astrophysics Data System (ADS)

    El-Aiat, M. M.; Kröger, F. A.

    1982-05-01

    Annealing of acceptor dominated α-Al2O3 at Tsat = 1100-1500 °C in atmospheres containing hydrogen leads to dissolution of hydrogen, changing the material from p- to n-type when the concentration of hydrogen donors is larger than that of the acceptor impurities present. If oxygen equilibrium is maintained, the concentration of ionized donors depends on pH2 as well as pO2 (or pH2O). In measurements of dc conductivity in atmospheres not containing hydrogen, a contribution to the conductivity by mobile protons rapidly disappears as a result of polarization. Analysis of the rate of polarization leads to values for the concentration and mobility of mobile protons. In measurements in atmospheres with well-defined hydrogen and oxygen fugacities, protons, native ions, and electrons and holes contribute continuously to the conductivity. Transference numbers of the various species and the corresponding partial conductivities were determined by emf measurements. The amount of dissolved hydrogen increases with decreasing temperature of saturation, increasing hydrogen pressure, and increasing oxygen pressure. Attempts to find detailed defect models explaining the results were only partially successful.

  17. Viscosity and thermal conductivity of model Jupiter atmospheres

    NASA Technical Reports Server (NTRS)

    Hansen, C. F.

    1979-01-01

    The viscosity and thermal conductivity coefficient are estimated for three models of the atmosphere of Jupiter: a heavy model consisting of 22% helium and 78% hydrogen, a nominal model consisting of 11% helium and 89% hydrogen, and a light model consisting of pure hydrogen. The effect of trace elements is neglected. Linearized approximations are used for the transport coefficients of the mixtures; these are found to be in almost constant ratio to the values for pure hydrogen, independent of temperature. Short Basic language programs for computing the coefficients are listed.

  18. Deviations from LTE in a stellar atmosphere

    NASA Technical Reports Server (NTRS)

    Kalkofen, W.; Klein, R. I.; Stein, R. F.

    1979-01-01

    Deviations for LTE are investigated in an atmosphere of hydrogen atoms with one bound level, satisfying the equations of radiative, hydrostatic, and statistical equilibrium. The departure coefficient and the kinetic temperature as functions of the frequency dependence of the radiative cross section are studied analytically and numerically. Near the outer boundary of the atmosphere, the departure coefficient is smaller than unity when the radiative cross section grows with frequency faster than with the square of frequency; it exceeds unity otherwise. Far from the boundary the departure coefficient tends to exceed unity for any frequency dependence of the radiative cross section. Overpopulation always implies that the kinetic temperature in the statistical-equilibrium atmosphere is higher than the temperature in the corresponding LTE atmosphere. Upper and lower bounds on the kinetic temperature are given for an atmosphere with deviations from LTE only in the optically shallow layers when the emergent intensity can be described by a radiation temperature.

  19. Biological cycling of atmospheric trace gases

    NASA Technical Reports Server (NTRS)

    Hitchcock, D. R.; Wechsler, A. E.

    1972-01-01

    A detailed critical review was conducted of present knowledge of the influence of biological processes on the cycling of selected atmospheric gas constituents--methane, carbon monoxide, and gaseous compounds of nitrogen (nitrous oxide, ammonia, nitric oxide, and nitrogen dioxide) and sulfur (hydrogen sulfide and sulfur dioxide). The identification was included of biological and other sources of each gas, a survey of abundance measurements reported in the literature, and a review of the atmospheric fate of each contituent. Information is provided on which to base conclusions regarding the importance of biological processes on the atmospheric distribution and surface-atmosphere exchange of each constituent, and a basis for estimating the adequacy of present knowledge of these factors. A preliminary analysis was conducted of the feasibility of monitoring the biologically influenced temporal and spatial variations in abundance of these gases in the atmosphere from satellites.

  20. Atmospheric Propagation

    NASA Technical Reports Server (NTRS)

    Embleton, Tony F. W.; Daigle, Gilles A.

    1991-01-01

    Reviewed here is the current state of knowledge with respect to each basic mechanism of sound propagation in the atmosphere and how each mechanism changes the spectral or temporal characteristics of the sound received at a distance from the source. Some of the basic processes affecting sound wave propagation which are present in any situation are discussed. They are geometrical spreading, molecular absorption, and turbulent scattering. In geometrical spreading, sound levels decrease with increasing distance from the source; there is no frequency dependence. In molecular absorption, sound energy is converted into heat as the sound wave propagates through the air; there is a strong dependence on frequency. In turbulent scattering, local variations in wind velocity and temperature induce fluctuations in phase and amplitude of the sound waves as they propagate through an inhomogeneous medium; there is a moderate dependence on frequency.

  1. Hydrogen calibration of GD-spectrometer using Zr-1Nb alloy

    NASA Astrophysics Data System (ADS)

    Mikhaylov, Andrey A.; Priamushko, Tatiana S.; Babikhina, Maria N.; Kudiiarov, Victor N.; Heller, Rene; Laptev, Roman S.; Lider, Andrey M.

    2018-02-01

    To study the hydrogen distribution in Zr-1Nb alloy (Э110 alloy) GD-OES was applied in this work. Qualitative analysis needs the standard samples with hydrogen. However, the standard samples with high concentrations of hydrogen in the zirconium alloy which would meet the requirements of the shape, size are absent. In this work method of Zr + H calibration samples production was performed at the first time. Automated Complex Gas Reaction Controller was used for samples hydrogenation. To calculate the parameters of post-hydrogenation incubation of the samples in an inert gas atmosphere the diffusion equations were used. Absolute hydrogen concentrations in the samples were determined by melting in the inert gas atmosphere using RHEN602 analyzer (LECO Company). Hydrogen distribution was studied using nuclear reaction analysis (HZDR, Dresden, Germany). RF GD-OES was used for calibration. The depth of the craters was measured with the help of a Hommel-Etamic profilometer by Jenoptik, Germany.

  2. Process and apparatus for coal hydrogenation

    DOEpatents

    Ruether, John A.; Simpson, Theodore B.

    1991-01-01

    In a coal liquefaction process an aqueous slurry of coal is prepared containing a dissolved liquefaction catalyst. A small quantity of oil is added to the slurry and then coal-oil agglomerates are prepared by agitation of the slurry at atmospheric pressure. The resulting mixture is drained of excess water and dried at atmospheric pressure leaving catalyst deposited on the agglomerates. The agglomerates then are fed to an extrusion device where they are formed into a continuous ribbon of extrudate and fed into a hydrogenation reactor at elevated pressure and temperature. The catalytic hydrogenation converts the extrudate primarily to liquid hydrocarbons in the reactor. The liquid drained in recovering the agglomerates is recycled.

  3. Hydrogen storage methods.

    PubMed

    Züttel, Andreas

    2004-04-01

    Hydrogen exhibits the highest heating value per mass of all chemical fuels. Furthermore, hydrogen is regenerative and environmentally friendly. There are two reasons why hydrogen is not the major fuel of today's energy consumption. First of all, hydrogen is just an energy carrier. And, although it is the most abundant element in the universe, it has to be produced, since on earth it only occurs in the form of water and hydrocarbons. This implies that we have to pay for the energy, which results in a difficult economic dilemma because ever since the industrial revolution we have become used to consuming energy for free. The second difficulty with hydrogen as an energy carrier is its low critical temperature of 33 K (i.e. hydrogen is a gas at ambient temperature). For mobile and in many cases also for stationary applications the volumetric and gravimetric density of hydrogen in a storage material is crucial. Hydrogen can be stored using six different methods and phenomena: (1) high-pressure gas cylinders (up to 800 bar), (2) liquid hydrogen in cryogenic tanks (at 21 K), (3) adsorbed hydrogen on materials with a large specific surface area (at T<100 K), (4) absorbed on interstitial sites in a host metal (at ambient pressure and temperature), (5) chemically bonded in covalent and ionic compounds (at ambient pressure), or (6) through oxidation of reactive metals, e.g. Li, Na, Mg, Al, Zn with water. The most common storage systems are high-pressure gas cylinders with a maximum pressure of 20 MPa (200 bar). New lightweight composite cylinders have been developed which are able to withstand pressures up to 80 MPa (800 bar) and therefore the hydrogen gas can reach a volumetric density of 36 kg.m(-3), approximately half as much as in its liquid state. Liquid hydrogen is stored in cryogenic tanks at 21.2 K and ambient pressure. Due to the low critical temperature of hydrogen (33 K), liquid hydrogen can only be stored in open systems. The volumetric density of liquid hydrogen

  4. Heated-Atmosphere Airship for the Titan Environment: Thermal Analysis

    NASA Technical Reports Server (NTRS)

    Heller, R. S.; Landis, G. A.; Hepp, A. F.; Colozza, A. J.

    2012-01-01

    Future exploration of Saturn's moon Titan can be carried out by airships. Several lighter-than-atmosphere gas airships and passive drifting heated-atmosphere balloon designs have been studied, but a heated-atmosphere airship could combine the best characteristics of both. This work analyses the thermal design of such a heated-atmosphere vehicle, and compares the result with a lighter-than-atmosphere (hydrogen) airship design. A design tool was created to enable iteration through different design parameters of a heated-atmosphere airship (diameter, number of layers, and insulating gas pocket thicknesses) and evaluate the feasibility of the resulting airship. A baseline heated-atmosphere airship was designed to have a diameter of 6 m (outer diameter of 6.2 m), three-layers of material, and an insulating gas pocket thickness of 0.05 m between each layer. The heated-atmosphere airship has a mass of 161.9 kg. A similar mission making use of a hydrogen-filled airship would require a diameter of 4.3 m and a mass of about 200 kg. For a long-duration mission, the heated-atmosphere airship appears better suited. However, for a mission lifetime under 180 days, the less complex hydrogen airship would likely be a better option.

  5. Ecliptic North-South Symmetry of Hydrogen Geocorona

    NASA Astrophysics Data System (ADS)

    Kameda, S.; Ikezawa, S.; Sato, M.; Kuwabara, M.; Osada, N.; Murakami, G.; Yoshioka, K.; Yoshikawa, I.; Taguchi, M.; Funase, R.; Sugita, S.; Miyoshi, Y.; Fujimoto, M.

    2017-12-01

    The hydrogen exosphere constitutes the uppermost atmospheric layer of the Earth, and its shape may reflect the last stage of the atmospheric escape process. The distribution of hydrogen in the outer exosphere remains unobserved because outer geocoronal emissions are difficult to observe from within the exosphere. In this study, we used the Lyman Alpha Imaging Camera on board the Proximate Object Close Flyby with Optical Navigation spacecraft, located outside the exosphere, to obtain the first image of the entire geocorona that extends to more than 38 Earth radii. The observed emission intensity distribution can be reproduced using our analytical model that has three parameters: exobase temperature, exobase density, and solar radiation pressure, which implies that hot hydrogen production in the magnetized plasmasphere is not the dominant process shaping the outer hydrogen exosphere. However, the role of the magnetic effect in determining the total escape flux cannot be ruled out.

  6. Electrochemical Measurement of Atmospheric Corrosion

    NASA Technical Reports Server (NTRS)

    DeArmond, Anna H.; Davis, Dennis D.; Beeson, Harold D.

    1999-01-01

    Corrosion of Shuttle thruster components in atmospheres containing high concentrations of nitrogen tetroxide (NTO) and water is an important issue in ground operations of bipropellant systems in humid locations. Measurements of the corrosivities of NTO-containing atmospheres and the responses of different materials to these atmospheres have been accomplished using an electrochemical sensor. The sensor is composed of alternating aluminum/titanium strips separated by thin insulating layers. Under high humidity conditions a thin film of water covers the surface of the sensor. Added NTO vapor reacts with the water film to form a conductive medium and establishes a galvanic cell. The current from this cell can be integrated with respect to time and related to the corrosion activity. The surface layer formed from humid air/NTO reacts in the same way as an aqueous solution of nitric acid. Nitric acid is generally considered an important agent in NTO corrosion situations. The aluminum/titanium sensor is unresponsive to dry air, responds slightly to humid air (> 75% RH), and responds strongly to the combination of humid air and NTO. The sensor response is a power function (n = 2) of the NTO concentration. The sensor does not respond to NTO in dry air. The response of other materials in this type of sensor is related to position of the material in a galvanic series in aqueous nitric acid. The concept and operation of this electrochemical corrosion measurement is being applied to other corrosive atmospheric contaminants such as hydrogen chloride, hydrogen fluoride, sulfur dioxide, and acidic aerosols.

  7. The PHOCUS Project: Atmospheric Composition

    NASA Astrophysics Data System (ADS)

    Hedin, J.; Gumbel, J.; Khaplanov, M.

    2012-12-01

    On the morning of July 21, 2011, the PHOCUS sounding rocket was launched from Esrange, Sweden, into strong noctilucent clouds (NLC) and polar mesosphere summer echoes (PMSE). The aim of the PHOCUS project (Particles, Hydrogen and Oxygen Chemistry in the Upper Summer mesosphere) is to study mesospheric particles (ice and meteoric smoke) and their interaction with their neutral and charged environment. Interactions of interest comprise the charging and nucleation of particles, the relationship between meteoric smoke and ice, and the influence of these particles on gas-phase chemistry. Here we will describe the optical measurements of the atmospheric composition and present first results including comparison to the other simultaneous measurements. The atmospheric composition was probed by a set of optical instruments from Stockholm University. The idea behind the instrument setup was to combine the advantages of the sensitive resonance fluorescence with well-calibrated airglow photometry. The set of instruments consisted of two resonance fluorescence probes (each containing a lamp and a detector), one for atomic oxygen and one for atomic hydrogen, and two IR photometers for O2 and OH dayglow emissions in the near IR. The O2 IR Atmospheric system at 1.27 μm is related to the photolysis of O3, which during the day is in steady state with O and a retrieval of O is possible. The OH Meinel emission is produced by the reaction between mesospheric O3 and H, and H concentrations can be deduced by combining information from both photometers. Unfortunately, some of these measurements were corrupted by instrument problems or payload glow. O3 and O profiles will be presented and compared to the simultaneous measurements of ice and meteoric smoke particles, water vapour and the state of the background neutral and charged atmosphere.

  8. Ultrafine hydrogen storage powders

    DOEpatents

    Anderson, Iver E.; Ellis, Timothy W.; Pecharsky, Vitalij K.; Ting, Jason; Terpstra, Robert; Bowman, Robert C.; Witham, Charles K.; Fultz, Brent T.; Bugga, Ratnakumar V.

    2000-06-13

    A method of making hydrogen storage powder resistant to fracture in service involves forming a melt having the appropriate composition for the hydrogen storage material, such, for example, LaNi.sub.5 and other AB.sub.5 type materials and AB.sub.5+x materials, where x is from about -2.5 to about +2.5, including x=0, and the melt is gas atomized under conditions of melt temperature and atomizing gas pressure to form generally spherical powder particles. The hydrogen storage powder exhibits improved chemcial homogeneity as a result of rapid solidfication from the melt and small particle size that is more resistant to microcracking during hydrogen absorption/desorption cycling. A hydrogen storage component, such as an electrode for a battery or electrochemical fuel cell, made from the gas atomized hydrogen storage material is resistant to hydrogen degradation upon hydrogen absorption/desorption that occurs for example, during charging/discharging of a battery. Such hydrogen storage components can be made by consolidating and optionally sintering the gas atomized hydrogen storage powder or alternately by shaping the gas atomized powder and a suitable binder to a desired configuration in a mold or die.

  9. Hydrogen interactions with metals

    NASA Technical Reports Server (NTRS)

    Mclellan, R. B.; Harkins, C. G.

    1975-01-01

    Review of the literature on the nature and extent of hydrogen interactions with metals and the role of hydrogen in metal failure. The classification of hydrogen-containing systems is discussed, including such categories as covalent hydrides, volatile hydrides, polymeric hydrides, and transition metal hydride complexes. The use of electronegativity as a correlating parameter in determining hydride type is evaluated. A detailed study is made of the thermodynamics of metal-hydrogen systems, touching upon such aspects as hydrogen solubility, the positions occupied by hydrogen atoms within the solvent metal lattice, the derivation of thermodynamic functions of solid solutions from solubility data, and the construction of statistical models for hydrogen-metal solutions. A number of theories of hydrogen-metal bonding are reviewed, including the rigid-band model, the screened-proton model, and an approach employing the augmented plane wave method to solve the one-electron energy band problem. Finally, the mechanism of hydrogen embrittlement is investigated on the basis of literature data concerning stress effects and the kinetics of hydrogen transport to critical sites.

  10. Potential environmental impact of a hydrogen economy on the stratosphere.

    PubMed

    Tromp, Tracey K; Shia, Run-Lie; Allen, Mark; Eiler, John M; Yung, Y L

    2003-06-13

    The widespread use of hydrogen fuel cells could have hitherto unknown environmental impacts due to unintended emissions of molecular hydrogen, including an increase in the abundance of water vapor in the stratosphere (plausibly by as much as approximately 1 part per million by volume). This would cause stratospheric cooling, enhancement of the heterogeneous chemistry that destroys ozone, an increase in noctilucent clouds, and changes in tropospheric chemistry and atmosphere-biosphere interactions.

  11. Analysis of hydrogen isotope mixtures

    DOEpatents

    Villa-Aleman, Eliel

    1994-01-01

    An apparatus and method for determining the concentrations of hydrogen isotopes in a sample. Hydrogen in the sample is separated from other elements using a filter selectively permeable to hydrogen. Then the hydrogen is condensed onto a cold finger or cryopump. The cold finger is rotated as pulsed laser energy vaporizes a portion of the condensed hydrogen, forming a packet of molecular hydrogen. The desorbed hydrogen is ionized and admitted into a mass spectrometer for analysis.

  12. Atmospheric electricity

    NASA Technical Reports Server (NTRS)

    1987-01-01

    In the last three years the focus was on the information contained in the lightning measurement, which is independent of other meteorological measurements that can be made from space. The characteristics of lightning activity in mesoscale convective systems were quantified. A strong relationship was found between lightning activity and surface rainfall. It is shown that lightning provides a precursor signature for wet microbursts (the strong downdrafts that produce windshears hazardous to aircraft) and that the lightning signature is a direct consequence of storm evolution. The Universities Space Research Association (USRA) collaborated with NASA scientists in the preliminary analysis and scientific justification for the design and deployment of an optical instrument which can detect lightning from geostationary orbit. Science proposals for the NASA mesoscale science program and for the Tethered Satellite System were reviewed. The weather forecasting research and unmanned space vehicles. Software was written to ingest and analyze the lightning ground strike data on the MSFC McIDAS system. The capabilities which were developed have a wide application to a number of problems associated with the operational impacts of electrical discharge within the atmosphere.

  13. Hydrogenation of carbonaceous materials

    DOEpatents

    Friedman, Joseph; Oberg, Carl L.; Russell, Larry H.

    1980-01-01

    A method for reacting pulverized coal with heated hydrogen-rich gas to form hydrocarbon liquids suitable for conversion to fuels wherein the reaction involves injection of pulverized coal entrained in a minimum amount of gas and mixing the entrained coal at ambient temperature with a separate source of heated hydrogen. In accordance with the present invention, the hydrogen is heated by reacting a small portion of the hydrogen-rich gas with oxygen in a first reaction zone to form a gas stream having a temperature in excess of about 1000.degree. C. and comprising a major amount of hydrogen and a minor amount of water vapor. The coal particles then are reacted with the hydrogen in a second reaction zone downstream of the first reaction zone. The products of reaction may be rapidly quenched as they exit the second reaction zone and are subsequently collected.

  14. HYDROGEN ISOTOPE TARGETS

    DOEpatents

    Ashley, R.W.

    1958-08-12

    The design of targets for use in the investigation of nuclear reactions of hydrogen isotopes by bombardment with accelerated particles is described. The target con struction eomprises a backing disc of a metal selected from the group consisting of molybdenunn and tungsten, a eoating of condensed titaniunn on the dise, and a hydrogen isotope selected from the group consisting of deuterium and tritium absorbed in the coatiag. The proeess for preparing these hydrogen isotope targets is described.

  15. Hydrogen powered bus

    ScienceCinema

    None

    2018-01-16

    Take a ride on a new type of bus, fueled by hydrogen. These hydrogen taxis are part of a Department of Energy-funded deployment of hydrogen powered vehicles and fueling infrastructure at nine federal facilities across the country to demonstrate this market-ready advanced technology. Produced and leased by Ford Motor Company , they consist of one 12- passenger bus and one nine-passenger bus. More information at: http://go.usa.gov/Tgr

  16. Hydrogen storage container

    DOEpatents

    Wang, Jy-An John; Feng, Zhili; Zhang, Wei

    2017-02-07

    An apparatus and system is described for storing high-pressure fluids such as hydrogen. An inner tank and pre-stressed concrete pressure vessel share the structural and/or pressure load on the inner tank. The system and apparatus provide a high performance and low cost container while mitigating hydrogen embrittlement of the metal tank. System is useful for distributing hydrogen to a power grid or to a vehicle refueling station.

  17. Oxygen and hydrogen accumulation at buried implantation-damage layers in hydrogen- and helium-implanted Czochralski silicon

    NASA Astrophysics Data System (ADS)

    Job, R.; Ulyashin, A. G.; Fahrner, W. R.; Ivanov, A. I.; Palmetshofer, L.

    Oxygen and hydrogen accumulations at buried implantation-damage layers were studied after post-implant-ation annealing of hydrogen- and helium-implanted Czochralski (Cz) silicon. Hydrogen implantation was carried out at energies E=180 keV and doses D=2.7×1016 cm-2, and helium implantation at E=300 keV and D=1016 cm-2. For comparison hydrogen implantation was also done into float-zone (Fz) silicon wafers. Post-implantation annealing at 1000 °C was done either in H2 or N2 atmosphere. Hydrogen and oxygen concentration profiles were measured by secondary ion mass spectroscopy (SIMS). It is shown that the ambient during annealing plays a significant role for the gettering of oxygen at buried implantation-damage layers in Cz Si. For both hydrogen and helium implantations, the buried defect layers act as rather effective getter centers for oxygen and hydrogen at appropriate conditions. The more efficient gettering of oxygen during post-implantation annealing in a hydrogen ambient can be attributed to a hydrogen-enhanced diffusion of oxygen towards the buried implantation-damage layers, where a fast oxygen accumulation occurs. Oxygen concentrations well above 1019 cm-3 can be obtained. From the comparison of measurements on hydrogen-implanted Cz Si and Fz Si one can conclude that at the buried defect layers hydrogen is most probably trapped by voids and/or may be stable as immobile molecular hydrogen species. Therefore hydrogen accumulated at the defect layers, and is preserved even after high-temperature annealing at 1000 °C.

  18. Thin film hydrogen sensor

    DOEpatents

    Lauf, Robert J.; Hoffheins, Barbara S.; Fleming, Pamela H.

    1994-01-01

    A hydrogen sensor element comprises an essentially inert, electrically-insulating substrate having a thin-film metallization deposited thereon which forms at least two resistors on the substrate. The metallization comprises a layer of Pd or a Pd alloy for sensing hydrogen and an underlying intermediate metal layer for providing enhanced adhesion of the metallization to the substrate. An essentially inert, electrically insulating, hydrogen impermeable passivation layer covers at least one of the resistors, and at least one of the resistors is left uncovered. The difference in electrical resistances of the covered resistor and the uncovered resistor is related to hydrogen concentration in a gas to which the sensor element is exposed.

  19. Hydrogen ion microlithography

    DOEpatents

    Tsuo, Y.S.; Deb, S.K.

    1990-10-02

    Disclosed is a hydrogen ion microlithography process for use in microelectronic fabrication and semiconductor device processing. The process comprises the steps of providing a single layer of either an amorphous silicon or hydrogenated amorphous silicon material. A pattern is recorded in a selected layer of amorphous silicon or hydrogenated amorphous silicon materials by preferentially implanting hydrogen ions therein so as to permit the selected layer to serve as a mask-resist wafer suitable for subsequent development and device fabrication. The layer is developed to provide a surface pattern therein adaptable for subsequent use in microelectronic fabrication and semiconductor device processing. 6 figs.

  20. Hydrogen ion microlithography

    DOEpatents

    Tsuo, Y. Simon; Deb, Satyen K.

    1990-01-01

    Disclosed is a hydrogen ion microlithography process for use in microelectronic fabrication and semiconductor device processing. The process comprises the steps of providing a single layer of either an amorphous silicon or hydrogenated amorphous silicon material. A pattern is recorded in a selected layer of amorphous silicon or hydrogenated amorphous silicon materials by preferentially implanting hydrogen ions therein so as to permit the selected layer to serve as a mask-resist wafer suitable for subsequent development and device fabrication. The layer is developed to provide a surface pattern therein adaptable for subsequent use in microelectronic fabrication and semiconductor device processing.

  1. Hydrogen energy creeps forward

    NASA Astrophysics Data System (ADS)

    Graff, G.

    1983-05-01

    There have been hopeful forecasts of a 21st centry 'hydrogen economy' in which cheap hydrogen fuel would finally end mankind's dependence on petroleum fuels. The present investigation is concerned with developments related to the possible realization of such forecasts. One vital factor involves the feasibility to provide hydrogen at competitive prices for use as a fuel. Industrial hydrogen is too expensive for applications involving a competition with currently used common fuels. A number of investigations are being conducted in the U.S. and in other countries with the aim to develop an economical process by which hydrogen can be obtained from water. There exist already a great number of feasible different approaches for obtaining hydrogen on the basis of the decomposition of the water molecule. However, problems still to be solved are related to the development of any of these approaches to the point of economic viability. Another crucial factor concerns the strorage of hydrogen. Automakers are testing hydrogen-powered cars in which hydrogen is stored in liquid form or with the aid of metal hydrides.

  2. Interaction of hydrogen with metal nitrides and imides

    NASA Astrophysics Data System (ADS)

    Chen, Ping; Xiong, Zhitao; Luo, Jizhong; Lin, Jianyi; Tan, Kuang Lee

    2002-11-01

    The pursuit of a clean and healthy environment has stimulated much effort in the development of technologies for the utilization of hydrogen-based energy. A critical issue is the need for practical systems for hydrogen storage, a problem that remains unresolved after several decades of exploration. In this context, the possibility of storing hydrogen in advanced carbon materials has generated considerable interest. But confirmation and a mechanistic understanding of the hydrogen-storage capabilities of these materials still require much work. Our previously published work on hydrogen uptake by alkali-doped carbon nanotubes cannot be reproduced by others. It was realized by us and also demonstrated by Pinkerton et al. that most of the weight gain was due to moisture, which the alkali oxide picked up from the atmosphere. Here we describe a different material system, lithium nitride, which shows potential as a hydrogen storage medium. Lithium nitride is usually employed as an electrode, or as a starting material for the synthesis of binary or ternary nitrides. Using a variety of techniques, we demonstrate that this compound can also reversibly take up large amounts of hydrogen. Although the temperature required to release the hydrogen at usable pressures is too high for practical application of the present material, we suggest that more investigations are needed, as the metal-N-H system could prove to be a promising route to reversible hydrogen storage.

  3. The chemistry of Venus' atmosphere

    NASA Technical Reports Server (NTRS)

    Sze, N. D.; Smith, W. H.

    1978-01-01

    A model for the Venus atmosphere involving photochemistry of oxygen, hydrogen, chlorine and sulfur species is presented. Sulfur reaction schemes and hydrogen and chlorine reaction schemes were included. The impact of sulfur on the oxygen budget and the subsequent production of H2SO4 molecules for the Venus cloud deck were explored. A major new reaction scheme for production of H2SO4 molecules involving sulfur and oxygen chemistry was established shown to dominate over the odd hydrogen scheme proposed earlier. The efficiency of the scheme in formation of H2SO4 is only about 50%, with the remaining sulfur residing in SO2 molecules. The calculated downward flux of H2SO4 may be sufficient to maintain a steady state sulfuric acid cloud if the resident time of H2SO4 droplets in the cloud is as long as a few years. If however, the resident time is half a year or shorter, additional chemistry capable of more efficient conversion of SO2 to SO3 is required.

  4. Hydrogen from biomass: state of the art and research challenges

    SciTech Connect

    Milne, Thomas A; Elam, Carolyn C; Evans, Robert J

    2002-02-01

    The report was prepared for the International Energy Agency (IEA) Agreement on the Production and Utilization of Hydrogen, Task 16, Hydrogen from Carbon-Containing Materials. Hydrogen's share in the energy market is increasing with the implementation of fuel cell systems and the growing demand for zero-emission fuels. Hydrogen production will need to keep pace with this growing market. In the near term, increased production will likely be met by conventional technologies, such as natural gas reforming. In these processes, the carbon is converted to CO2 and released to the atmosphere. However, with the growing concern about global climate change, alternatives tomore » the atmospheric release of CO2 are being investigated. Sequestration of the CO2 is an option that could provide a viable near-term solution. Reducing the demand on fossil resources remains a significant concern for many nations. Renewable-based processes like solar- or wind-driven electrolysis and photobiological water splitting hold great promise for clean hydrogen production; however, advances must still be made before these technologies can be economically competitive. For the near-and mid-term, generating hydrogen from biomass may be the more practical and viable, renewable and potentially carbon-neutral (or even carbon-negative in conjunction with sequestration) option. Recently, the IEA Hydrogen Agreement launched a new task to bring together international experts to investigate some of these near- and mid-term options for producing hydrogen with reduced environmental impacts. This review of the state of the art of hydrogen production from biomass was prepared to facilitate in the planning of work that should be done to achieve the goal of near-term hydrogen energy systems. The relevant technologies that convert biomass to hydrogen, with emphasis on thermochemical routes are described. In evaluating the viability of the conversion routes, each must be put in the context of the availability of

  5. Materials for the scavanging of hydrogen at high temperatures

    DOEpatents

    Shepodd, Timothy J.; Phillip, Bradley L.

    1997-01-01

    A hydrogen getter composition comprising a double or triple bonded hydrocarbon with a high melting point useful for removing hydrogen gas, to partial pressures below 0.01 torr, from enclosed spaces and particularly from vessels used for transporting or containing fluids at elevated temperatures. The hydrogen getter compositions disclosed herein and their reaction products will neither melt nor char at temperatures in excess of 100.degree. C. They possess significant advantages over conventional hydrogen getters, namely low risk of fire or explosion, no requirement for high temperature activation or operation, the ability to absorb hydrogen even in the presence of contaminants such as water, water vapor, common atmospheric gases and oil mists and are designed to be disposed within the confines of the apparatus. These getter materials can be mixed with binders, such as fluropolymers, which permit the getter material to be fabricated into useful shapes and/or impart desirable properties such as water repellency or impermeability to various gases.

  6. Materials for the scavanging of hydrogen at high temperatures

    DOEpatents

    Shepodd, Timothy J.; Phillip, Bradley L.

    1997-01-01

    A hydrogen getter composition comprising a double or triple bonded hydrocarbon with a high melting point useful for removing hydrogen gas, to partial pressures below 0.01 torr, from enclosed spaces and particularly from vessels used for transporting or containing fluids at elevated temperatures. The hydrogen getter compostions disclosed herein and their reaction products will neither melt nor char at temperatures in excess of 100C. They possess significant advantages over conventional hydrogen getters, namely low risk of fire or explosion, no requirement for high temperature activation or operation, the ability to absorb hydrogen even in the presence of contaminants such as water, water vapor, common atmospheric gases and oil mists and are designed to be disposed within the confines of the apparatus. These getter materials can be mixed with binders, such as fluropolymers, which permit the getter material to be fabricated into useful shapes and/or impart desirable properties such as water repellency or impermeability to various gases.

  7. Hydrogen-Helium shock Radiation tests for Saturn Entry Probes

    NASA Technical Reports Server (NTRS)

    Cruden, Brett A.

    2016-01-01

    This paper describes the measurement of shock layer radiation in Hydrogen/Helium mixtures representative of that encountered by probes entering the Saturn atmosphere. Normal shock waves are measured in Hydrogen-Helium mixtures (89:11% by volume) at freestream pressures between 13-66 Pa (0.1-0.5 Torr) and velocities from 20-30 km/s. Radiance is quantified from the Vacuum Ultraviolet through Near Infrared. An induction time of several centimeters is observed where electron density and radiance remain well below equilibrium. Radiance is observed in front of the shock layer, the characteristics of which match the expected diffusion length of Hydrogen.

  8. Triple redundant hydrogen sensor with in situ calibration

    NASA Technical Reports Server (NTRS)

    Lantz, J. B.; Powell, J. D.; Schubert, F. H.; Koszenski, E. P.

    1980-01-01

    To meet sensing and calibration needs, an in situ calibration technique was developed. It is based on electrolytic generation of a hydrogen/air atmosphere within a hydrogen sensor. The hydrogen is generated from water vapor in the air, and being electrical in nature, the in situ calibration can be performed completely automatically in remote locations. Triply redundant sensor elements are integrated within a single, compact housing, and digital logic provides inter-sensor comparisons to warn of and identify malfunctioning sensor elements. An evaluation of this concept is presented.

  9. Combination moisture and hydrogen getter

    DOEpatents

    Harrah, L.A.; Mead, K.E.; Smith, H.M.

    1983-09-20

    A combination moisture and hydrogen getter comprises (a) a moisture getter comprising a readily oxidizable metal; and (b) a hydrogen getter comprising (1) a solid acetylenic compound and (2) a hydrogenation catalyst. A method of scavenging moisture from a closed container uses the combination moisture and hydrogen getter to irreversibly chemically reduce the moisture and chemically bind the resultant hydrogen.

  10. Combination moisture and hydrogen getter

    DOEpatents

    Harrah, Larry A.; Mead, Keith E.; Smith, Henry M.

    1983-01-01

    A combination moisture and hydrogen getter comprises (a) a moisture getter comprising a readily oxidizable metal; and (b) a hydrogen getter comprising (i) a solid acetylenic compound and (ii) a hydrogenation catalyst. A method of scavenging moisture from a closed container uses the combination moisture and hydrogen getter to irreversibly chemically reduce the moisture and chemically bind the resultant hydrogen.

  11. Combination moisture and hydrogen getter

    DOEpatents

    Not Available

    1982-04-29

    A combination moisture and hydrogen getter comprises (a) a moisture getter comprising a readily oxidizable metal; and (b) a hydrogen getter comprising (i) a solid acetylenic compound and (ii) a hydrogenation catalyst. A method of scavenging moisture from a closed container uses the combination moisture and hydrogen getter to irreversibly chemically reduce the moisture and chemically bind the reusltant hydrogen.

  12. Enhancing hydrogen spillover and storage

    DOEpatents

    Yang, Ralph T [Ann Arbor, MI; Li, Yingwel [Ann Arbor, MI; Lachawiec, Jr., Anthony J.

    2011-05-31

    Methods for enhancing hydrogen spillover and storage are disclosed. One embodiment of the method includes doping a hydrogen receptor with metal particles, and exposing the hydrogen receptor to ultrasonification as doping occurs. Another embodiment of the method includes doping a hydrogen receptor with metal particles, and exposing the doped hydrogen receptor to a plasma treatment.

  13. Enhancing hydrogen spillover and storage

    DOEpatents

    Yang, Ralph T; Li, Yingwei; Lachawiec, Jr., Anthony J

    2013-02-12

    Methods for enhancing hydrogen spillover and storage are disclosed. One embodiment of the method includes doping a hydrogen receptor with metal particles, and exposing the hydrogen receptor to ultrasonication as doping occurs. Another embodiment of the method includes doping a hydrogen receptor with metal particles, and exposing the doped hydrogen receptor to a plasma treatment.

  14. The atomic hydrogen cloud in the saturnian system

    NASA Astrophysics Data System (ADS)

    Tseng, W.-L.; Johnson, R. E.; Ip, W.-H.

    2013-09-01

    The importance of Titan's H torus shaped by solar radiation pressure and of hydrogen atoms flowing out of Saturn's atmosphere in forming the broad hydrogen cloud in Saturn's magnetosphere is still debated. Since the Saturnian system also contains a water product torus which originates from the Enceladus plumes, the icy ring particles, and the inner icy satellites, as well as Titan's H2 torus, we have carried out a global investigation of the atomic hydrogen cloud taking into account all sources. We show that the velocity and angle distributions of the hot H ejected from Saturn's atmosphere following electron-impact dissociation of H2 are modified by collisions with the ambient atmospheric H2 and H. This in turn affects the morphology of the escaping hydrogen from Saturn, as does the morphology of the ionospheric electron distribution. Although an exact agreement with the Cassini observations is not obtained, our simulations show that H directly escaping from Titan is the dominant contributor in the outer magnetosphere. Of the total number of H observed by Cassini from 1 to 5RS, ∼5.7×1034, our simulations suggest ∼20% is from dissociation in the Enceladus torus, ∼5-10% is from dissociation of H2 in the atmosphere of the main rings, and ∼50% is from Titan's H torus, implying that ∼20% comes from Saturn atmosphere.

  15. Mars Molniya Orbit Atmospheric Resource Mining

    NASA Technical Reports Server (NTRS)

    Mueller, Robert P.; Braun, Robert D.; Sibille, Laurent; Sforzo, Brandon; Gonyea, Keir; Ali, Hisham

    2016-01-01

    This NIAC (NASA Advanced Innovative Concepts) work will focus on Mars and will build on previous efforts at analyzing atmospheric mining at Earth and the outer solar system. Spacecraft systems concepts will be evaluated and traded, to assess feasibility. However the study will primarily examine the architecture and associated missions to explore the closure, constraints and critical parameters through sensitivity studies. The Mars atmosphere consists of 95.5 percent CO2 gas which can be converted to methane fuel (CH4) and Oxidizer (O2) for chemical rocket propulsion, if hydrogen is transported from electrolyzed water on the Mars surface or from Earth. By using a highly elliptical Mars Molniya style orbit, the CO2 atmosphere can be scooped, ram-compressed and stored while the spacecraft dips into the Mars atmosphere at periapsis. Successive orbits result in additional scooping of CO2 gas, which also serves to aerobrake the spacecraft, resulting in a decaying Molniya orbit.

  16. Photochemically driven collapse of Titan's atmosphere.

    PubMed

    Lorenz, R D; McKay, C P; Lunine, J I

    1997-01-31

    Saturn's giant moon Titan has a thick (1.5 bar) nitrogen atmosphere, which has a temperature structure that is controlled by the absorption of solar and thermal radiation by methane, hydrogen, and organic aerosols into which methane is irreversibly converted by photolysis. Previous studies of Titan's climate evolution have been done with the assumption that the methane abundance was maintained against photolytic depletion throughout Titan's history, either by continuous supply from the interior or by buffering by a surface or near surface reservoir. Radiative-convective and radiative-saturated equilibrium models of Titan's atmosphere show that methane depletion may have allowed Titan's atmosphere to cool so that nitrogen, its main constituent, condenses onto the surface, collapsing Titan into a Triton-like frozen state with a thin atmosphere.

  17. Process for exchanging hydrogen isotopes between gaseous hydrogen and water

    DOEpatents

    Hindin, Saul G.; Roberts, George W.

    1980-08-12

    A process for exchanging isotopes of hydrogen, particularly tritium, between gaseous hydrogen and water is provided whereby gaseous hydrogen depeleted in tritium and liquid or gaseous water containing tritium are reacted in the presence of a metallic catalyst.

  18. Membrane for hydrogen recovery from streams containing hydrogen sulfide

    DOEpatents

    Agarwal, Pradeep K.

    2007-01-16

    A membrane for hydrogen recovery from streams containing hydrogen sulfide is provided. The membrane comprises a substrate, a hydrogen permeable first membrane layer deposited on the substrate, and a second membrane layer deposited on the first layer. The second layer contains sulfides of transition metals and positioned on the on a feed side of the hydrogen sulfide stream. The present invention also includes a method for the direct decomposition of hydrogen sulfide to hydrogen and sulfur.

  19. Thick film hydrogen sensor

    DOEpatents

    Hoffheins, B.S.; Lauf, R.J.

    1995-09-19

    A thick film hydrogen sensor element includes an essentially inert, electrically-insulating substrate having deposited thereon a thick film metallization forming at least two resistors. The metallization is a sintered composition of Pd and a sinterable binder such as glass frit. An essentially inert, electrically insulating, hydrogen impermeable passivation layer covers at least one of the resistors. 8 figs.

  20. Thick film hydrogen sensor

    DOEpatents

    Hoffheins, Barbara S.; Lauf, Robert J.

    1995-01-01

    A thick film hydrogen sensor element includes an essentially inert, electrically-insulating substrate having deposited thereon a thick film metallization forming at least two resistors. The metallization is a sintered composition of Pd and a sinterable binder such as glass frit. An essentially inert, electrically insulating, hydrogen impermeable passivation layer covers at least one of the resistors.

  1. Metastable ultracondensed hydrogenous materials

    NASA Astrophysics Data System (ADS)

    Nellis, W. J.

    2017-12-01

    The primary purpose of this paper is to stimulate theoretical predictions of how to retain metastably hydrogenous materials made at high pressure P on release to ambient. Ultracondensed metallic hydrogen has been made at high pressures in the fluid and reported made probably in the solid. Because the long quest for metallic hydrogen is likely to be concluded in the relatively near future, a logical question is whether another research direction, comparable in scale to the quest for metallic H, will arise in high pressure research. One possibility is retention of metastable solid metallic hydrogen and other hydrogenous materials on release of dynamic and static high pressures P to ambient. If hydrogenous materials could be retained metastably on release, those materials would be a new class of materials for scientific investigations and technological applications. This paper is a review of the current situation with the synthesis of metallic hydrogen, potential technological applications of metastable metallic H and other hydrogenous materials at ambient, and general background of published experimental and theoretical work on what has been accomplished with metastable phases in the past and thus what might be accomplished in the future.

  2. Hydrogen evolution reaction catalyst

    DOEpatents

    Subbaraman, Ram; Stamenkovic, Vojislav; Markovic, Nenad; Tripkovic, Dusan

    2016-02-09

    Systems and methods for a hydrogen evolution reaction catalyst are provided. Electrode material includes a plurality of clusters. The electrode exhibits bifunctionality with respect to the hydrogen evolution reaction. The electrode with clusters exhibits improved performance with respect to the intrinsic material of the electrode absent the clusters.

  3. Atmospheric transformation of volatile organic compounds

    NASA Astrophysics Data System (ADS)

    Henley, Michael V.; Bradley, William R.; Wyatt, Sheryl E.; Graziano, G. M.; Wells, J. R.

    2000-07-01

    To be able to understand and predict the concentration of a target compound in the atmosphere one must understand the atmospheric chemistry involved. The transformation of volatile organic compounds in the troposphere is predominantly driven by the interaction with the hydroxyl and nitrate radicals. The hydroxyl radical exists in daylight conditions and its reaction rate constant with an organic compound is typically very fast. The nitrate radical drives the nighttime chemistry. These radicals can scavenge hydrogen from an organic molecule generating secondary products that are often overlooked in detection schemes. Secondary products can be more stable and serve as a better target compound in detection schemes. The gas phase reaction of the hydroxyl radical (OH) with cyclohexanol (COL) has been studied. The rate coefficient was determined to be (19.0 +/- 4.8) X 10-12 cm3 molecule-1 s-1 (at 297 +/- 3 K and 1 atmosphere total pressure) using the relative rate technique with pentanal, decane, and tridecane as the reference compounds. Assuming an average OH concentration of 1 X 106 molecules cm-3, an atmospheric lifetime of 15 h is calculated for cyclohexanol. Products of the OH + COL reaction were determined to more clearly define cyclohexanol's atmospheric degradation mechanism. The observed products were: cyclohexanone, hexanedial, 3- hydroxycyclohexanone, and 4-hydroxycyclohexanone. Consideration of the potential reaction pathways suggest that each of these products is formed via hydrogen abstraction at a different site on the cyclohexanol ring.

  4. Imaging shock fronts in Mira atmospheres .

    NASA Astrophysics Data System (ADS)

    Woodruff, H. C.; Lloyd, J. P.; ten Brummelaar, T.; Scholz, M.; Turner, N.; Tuthill, P. G.

    One of the most rewarding observations for probing Mira atmospheres is the imaging and determination of the position of the schock-front. The hot post-shock material is seen in the spectrum by typical emission lines, in particular the Balmer series of hydrogen. The hot zone is very narrow (\\citealt{fw}), and its influence on atmospheric temperatures and photon fluxes is usually neglected in Mira models (\\citealt{bsw}, \\citealt{hsw}, see also \\citealt{beach88} and \\citealt{bessel89}). Balmer line fluxes are, however, strong enough to be accessible to high-precision interferometry (from \\citealt{scho}).

  5. Homeostatic tendencies of the earth's atmosphere

    NASA Technical Reports Server (NTRS)

    Lovelock, J. E.; Margulis, L.

    1974-01-01

    The concept is developed that the atmosphere of the earth flows in a closed system controlled by and for the biosphere. The environmental factors delimiting the biosphere are examined. It is found that neither oxygen nor pressure per se limit the distribution of life as a whole. Rather the major physical variables determining the distribution of organisms are solar radiation, temperature, water abundance, and the concentrations of hydrogen and other ions and elements. An attempt is made to model temperature and atmospheric composition of a lifeless earth.

  6. Tandem hydroformylation/hydrogenation of alkenes to normal alcohols using Rh/Ru dual catalyst or Ru single component catalyst.

    PubMed

    Takahashi, Kohei; Yamashita, Makoto; Nozaki, Kyoko

    2012-11-14

    The catalyst system for tandem hydroformylation/hydrogenation of terminal alkenes to the corresponding homologated normal alcohol was developed. The reaction mechanism for the Rh/Ru dual catalyst was investigated by real-time IR monitoring experiments and (31)P NMR spectroscopy, which proved the mutual orthogonality of Rh-catalyzed hydroformylation and Ru-catalyzed hydrogenation. Detailed investigation about Ru-catalyzed hydrogenation of undecanal under H(2)/CO pressure clarified different kinetics from the hydrogenation under H(2) and gave a clue to design more active hydrogenation catalysts under H(2)/CO atmosphere. The solely Ru-catalyzed normal selective hydroformylation/hydrogenation is also reported.

  7. A HIGHLY EFFICIENT OXIDATION OF CYCLOHEXANE OVER VPO CATALYSTS USING HYDROGEN PEROXIDE

    EPA Science Inventory

    An unprecedented and highly efficient oxidation of cyclohexane to cyclohexanol and cyclohexanone is accomplished over calcined vanadium phosphorus oxide (VPO) catalysts in a relatively mild condition using hydrogen peroxide under a nitrogen atmosphere.

  8. Challenges in hydrogen storage

    NASA Astrophysics Data System (ADS)

    Schüth, F.

    2009-09-01

    Hydrogen is one possible medium for energy storage and transportation in an era beyond oil. Hydrogen appears to be especially promising in connection with electricity generation in polymer electrolyte membrane (PEM) fuel cells in cars. However, before such technologies can be implemented on a larger scale, satisfactory solutions for on-board storage of hydrogen are required. This is a difficult task due to the low volumetric and gravimetric storage density on a systems level which can be achieved so far. Possibilities include cryogenic storage as liquid hydrogen, high pressure storage at 70 MPa, (cryo)adsorptive storage, or various chemical methods of binding and releasing hydrogen. This survey discusses the different options and the associated advantages and disadvantages.

  9. Hydrogen Peroxide Concentrator

    NASA Technical Reports Server (NTRS)

    Parrish, Clyde F.

    2007-01-01

    A relatively simple and economical process and apparatus for concentrating hydrogen peroxide from aqueous solution at the point of use have been invented. The heart of the apparatus is a vessel comprising an outer shell containing tubular membranes made of a polymer that is significantly more permeable by water than by hydrogen peroxide. The aqueous solution of hydrogen peroxide to be concentrated is fed through the interstitial spaces between the tubular membranes. An initially dry sweep gas is pumped through the interiors of the tubular membranes. Water diffuses through the membranes and is carried away as water vapor mixed into the sweep gas. Because of the removal of water, the hydrogen peroxide solution flowing from the vessel at the outlet end is more concentrated than that fed into the vessel at the inlet end. The sweep gas can be air, nitrogen, or any other gas that can be conveniently supplied in dry form and does not react chemically with hydrogen peroxide.

  10. Atomic hydrogen rocket engine

    NASA Technical Reports Server (NTRS)

    Etters, R. D.; Flurchick, K.

    1981-01-01

    A rocket using atomic hydrogen propellant is discussed. An essential feature of the proposed engine is that the atomic hydrogen fuel is used as it is produced, thus eliminating the necessity of storage. The atomic hydrogen flows into a combustion chamber and recombines, producing high velocity molecular hydrogen which flows out an exhaust port. Standard thermodynamics, kinetic theory and wall recombination cross-sections are used to predict a thrust of approximately 1.4 N for a RF hydrogen flow rate of 4 x 10 to the 22nd/sec. Specific impulses are nominally from 1000 to 2000 sec. It is predicted that thrusts on the order of one Newton and specific impulses of up to 2200 sec are attainable with nominal RF discharge fluxes on the order of 10 to the 22nd atoms/sec; further refinements will probably not alter these predictions by more than a factor of two.

  11. Liquid Hydrogen Fill

    NASA Image and Video Library

    2016-08-03

    Technicians with Praxair pressurize the hydrogen trailer before offloading liquid hydrogen during a test of the Ground Operations Demo Unit for liquid hydrogen at NASA's Kennedy Space Center in Florida. The system includes a 33,000 gallon liquid hydrogen storage tank with an internal cold heat exchanger supplied from a cryogenic refrigerator. The primary goal of the testing is to achieve a liquid hydrogen zero boil-off capability. The system was designed, installed and tested by a team of civil servants and contractors from the center's Cryogenic Test Laboratory, with support from engineers at NASA's Glenn Research Center in Cleveland and Stennis Space Center in Mississippi. It may be applicable for use by the Ground Systems Development and Operations Program at Launch Pad 39B.

  12. Greenhouse models of the atmosphere of Titan.

    NASA Technical Reports Server (NTRS)

    Pollack, J. B.

    1973-01-01

    The greenhouse effect is calculated for a series of Titanian atmosphere models with different proportions of methane, hydrogen, helium, and ammonia. A computer program is used in temperature-structure calculations based on radiative-convective thermal transfer considerations. A brightness temperature spectrum is derived for Titan and is compared with available observational data. It is concluded that the greenhouse effect on Titan is generated by pressure-induced transitions of methane and hydrogen. The helium-to-hydrogen ratio is found to have a maximum of about 1.5. The surface pressure is estimated to be at least 0.4 atm, with a daytime temperature of about 155 K at the surface. The presence of methane clouds in the upper troposphere is indicated. The clouds have a significant optical depth in the visible, but not in the thermal, infrared.

  13. Hydrogen embrittlement property of a 1700-MPa-class ultrahigh-strength tempered martensitic steel.

    PubMed

    Li, Songjie; Akiyama, Eiji; Yuuji, Kimura; Tsuzaki, Kaneaki; Uno, Nobuyoshi; Zhang, Boping

    2010-04-01

    The hydrogen embrittlement property of a prototype 1700-MPa-class ultrahigh-strength steel (NIMS17) containing hydrogen traps was evaluated using a slow strain rate test (SSRT) after cathodic hydrogen precharging, cyclic corrosion test (CCT) and atmospheric exposure. The hydrogen content in a fractured specimen was measured after SSRT by thermal desorption spectroscopy (TDS). The relationship between fracture stress and hydrogen content for the hydrogen-precharged specimens showed that the fracture stress of NIMS17 steel was higher, at a given hydrogen content, than that of conventional AISI 4135 steels with tensile strengths of 1300 and 1500 MPa. This suggests better resistance of NIMS17 steel to hydrogen embrittlement. However, hydrogen uptake to NIMS17 steel under CCT and atmospheric exposure decreased the fracture stress. This is because of the stronger hydrogen uptake to the steel containing hydrogen traps than to the AISI 4135 steels. Although NIMS17 steel has a higher strength level than AISI 4135 steel with a tensile strength of 1500 MPa, the decrease in fracture stress is similar between these steels.

  14. Hydrogen embrittlement property of a 1700-MPa-class ultrahigh-strength tempered martensitic steel

    NASA Astrophysics Data System (ADS)

    Li, Songjie; Akiyama, Eiji; Yuuji, Kimura; Tsuzaki, Kaneaki; Uno, Nobuyoshi; Zhang, Boping

    2010-04-01

    The hydrogen embrittlement property of a prototype 1700-MPa-class ultrahigh-strength steel (NIMS17) containing hydrogen traps was evaluated using a slow strain rate test (SSRT) after cathodic hydrogen precharging, cyclic corrosion test (CCT) and atmospheric exposure. The hydrogen content in a fractured specimen was measured after SSRT by thermal desorption spectroscopy (TDS). The relationship between fracture stress and hydrogen content for the hydrogen-precharged specimens showed that the fracture stress of NIMS17 steel was higher, at a given hydrogen content, than that of conventional AISI 4135 steels with tensile strengths of 1300 and 1500 MPa. This suggests better resistance of NIMS17 steel to hydrogen embrittlement. However, hydrogen uptake to NIMS17 steel under CCT and atmospheric exposure decreased the fracture stress. This is because of the stronger hydrogen uptake to the steel containing hydrogen traps than to the AISI 4135 steels. Although NIMS17 steel has a higher strength level than AISI 4135 steel with a tensile strength of 1500 MPa, the decrease in fracture stress is similar between these steels.

  15. Hydrogen embrittlement property of a 1700-MPa-class ultrahigh-strength tempered martensitic steel

    PubMed Central

    Li, Songjie; Akiyama, Eiji; Yuuji, Kimura; Tsuzaki, Kaneaki; Uno, Nobuyoshi; Zhang, Boping

    2010-01-01

    The hydrogen embrittlement property of a prototype 1700-MPa-class ultrahigh-strength steel (NIMS17) containing hydrogen traps was evaluated using a slow strain rate test (SSRT) after cathodic hydrogen precharging, cyclic corrosion test (CCT) and atmospheric exposure. The hydrogen content in a fractured specimen was measured after SSRT by thermal desorption spectroscopy (TDS). The relationship between fracture stress and hydrogen content for the hydrogen-precharged specimens showed that the fracture stress of NIMS17 steel was higher, at a given hydrogen content, than that of conventional AISI 4135 steels with tensile strengths of 1300 and 1500 MPa. This suggests better resistance of NIMS17 steel to hydrogen embrittlement. However, hydrogen uptake to NIMS17 steel under CCT and atmospheric exposure decreased the fracture stress. This is because of the stronger hydrogen uptake to the steel containing hydrogen traps than to the AISI 4135 steels. Although NIMS17 steel has a higher strength level than AISI 4135 steel with a tensile strength of 1500 MPa, the decrease in fracture stress is similar between these steels. PMID:27877333

  16. Measuring Hydrogen Concentrations in Metals

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1985-01-01

    Commercial corrosion-measurement system adapted to electrochemical determination of hydrogen concentrations in metals. New technique based on diffusion of hydrogen through foil specimen of metal. In sample holder, hydrogen produced on one side of foil, either by corrosion reaction or by cathodic current. Hydrogen diffused through foil removed on other side by constant anode potential, which leads to oxidation of hydrogen to water. Anode current is measure of concentration of hydrogen diffusing through foil. System used to study hydrogen uptake, hydrogen elimination by baking, effect of heat treatment, and effect of electroplating on high-strength steels.

  17. Adsorption of hydrogen chloride on microcrystalline silica. [solid rocket propellant exhaust

    NASA Technical Reports Server (NTRS)

    Kang, Y.; Wightman, J. P.

    1979-01-01

    The interaction of hydrogen chloride with quartz was studied to determine the extent to which silica can irreversibly remove hydrogen chloride from the atmosphere. Adsorption isotherms were measured at 30 C for hydrogen chloride on silica outgassed between 100 C and 400 C. Readsorption isotherms were also measured. The silica surface was characterized further by infrared spectroscopy, electron spectroscopy for chemical analysis, scanning electron microscopy, and immersional calorimetry. Ground debris samples obtained from the Kennedy Space Center, were likewise examined.

  18. Hydrogenation of sulfoxides to sulfides under mild conditions using ruthenium nanoparticle catalysts.

    PubMed

    Mitsudome, Takato; Takahashi, Yusuke; Mizugaki, Tomoo; Jitsukawa, Koichiro; Kaneda, Kiyotomi

    2014-08-04

    The first demonstration of the hydrogenation of sulfoxides under atmospheric H2 pressure is reported. The highly efficient reaction is facilitated by a heterogeneous Ru nanoparticle catalyst. The mild reaction conditions enable the selective hydrogenation of a wide range of functionalized sulfoxides to the corresponding sulfides. The high redox ability of RuO(x) nanoparticles plays a key role in the hydrogenation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Hydrogen halide cleaning of powder metallurgy nickel-20 chromium-3 thoria.

    NASA Technical Reports Server (NTRS)

    Herbell, T. P.

    1972-01-01

    The Cr2O3 content of powder metallurgy nickel-20 chromium-3 thoria was reduced with atmospheres consisting of hydrogen plus hydrogen chloride (HCl) or hydrogen bromide (HBr). The nonthoria oxygen content or 'oxygen excess' was reduced from an initial amount of greater than 50,000 ppm to less than 100 ppm. Low temperatures were effective, but lowest oxygen levels were achieved with the highest cleaning temperature of 1200 C.

  20. Hydrogen production from biomass

    NASA Astrophysics Data System (ADS)

    Hahn, John J.

    Biomass energy encompasses a broad category of energy derived from plants and animals as well as the residual materials from each. Hydrogen gas is an effective energy carrier which burns cleanly producing water as the only product. Hydrogen produced from a renewable source such as biomass provides a domestically available, CO2 neutral, non-polluting form of energy. The goal of the work presented in this thesis was to develop two different methods to produce hydrogen gas using biomass as a renewable energy source. The first method was to produce hydrogen using photosynthetic algae. C. reinhardtii has been shown to produce hydrogen using light as an energy source. The objective of this work was to increase hydrogen production by (a) manipulating process variables such as cell concentration, light intensity, and reactor design and (b) immobilizing the algal cells to increase photosynthetic efficiency and address production limitations. The second method of hydrogen production explored was gasification of biomass using supercritical water (SCW). A continuous SCW reactor was constructed to increase capacity and understand the optimum conditions necessary to gasify model compounds. Increasing the capacity of SCW reactors and understanding how basic components of biomass react may lead to further development of this technology.

  1. Ignition and flame characteristics of cryogenic hydrogen releases

    DOE PAGES

    Panda, Pratikash P.; Hecht, Ethan S.

    2017-01-01

    In this work, under-expanded cryogenic hydrogen jets were investigated experimentally for their ignition and flame characteristics. The test facility described herein, was designed and constructed to release hydrogen at a constant temperature and pressure, to study the dispersion and thermo-physical properties of cryogenic hydrogen releases and flames. In this study, a non-intrusive laser spark focused on the jet axis was used to measure the maximum ignition distance. The radiative power emitted by the corresponding jet flames was also measured for a range of release scenarios from 37 K to 295 K, 2–6 bar abs through nozzles with diameters from 0.75more » to 1.25 mm. The maximum ignition distance scales linearly with the effective jet diameter (which scales as the square root of the stagnant fluid density). A 1-dimensional (stream-wise) cryogenic hydrogen release model developed previously at Sandia National Laboratories (although this model is not yet validated for cryogenic hydrogen) was exercised to predict that the mean mole fraction at the maximum ignition distance is approximately 0.14, and is not dependent on the release conditions. The flame length and width were extracted from visible and infra-red flame images for several test cases. The flame length and width both scale as the square root of jet exit Reynolds number, as reported in the literature for flames from atmospheric temperature hydrogen. As shown in previous studies for ignited atmospheric temperature hydrogen, the radiative power from the jet flames of cold hydrogen scales as a logarithmic function of the global flame residence time. The radiative heat flux from jet flames of cold hydrogen is higher than the jet flames of atmospheric temperature hydrogen, for a given mass flow rate, due to the lower choked flow velocity of low-temperature hydrogen. Lastly, this study provides critical information with regard to the development of models to inform the safety codes and standards of hydrogen

  2. Response of Thermospheric Hydrogen to Solar Variability and Greenhouse Gases

    NASA Astrophysics Data System (ADS)

    Nossal, S. M.; Qian, L.; Solomon, S. C.; Burns, A. G.; Wang, W.; Mierkiewicz, E. J.; Roesler, F. L.; Woodward, R. C., Jr.

    2015-12-01

    Geocoronal hydrogen forms the upper boundary of the Earth's HOx chemisty and is a byproduct of methane and water vapor below. We will discuss observational and modeling studies of the upper atmospheric hydrogen response to the solar cycle and increases in greenhouse gases. The Wisconsin Northern hemisphere hydrogen airglow data set spans over two solar cycles. These data show a statistically significant solar cycle variation and a possible increase in intensity between successive solar maximum periods. We will discuss these data in the context of recent modeling studies with a single-column version of the Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model. We investigate mechanisms associated with the solar cycle and greenhouse gas forcing of hydrogen by separately doubling carbon dioxide and methane, as well as doubling both together. These simulations indicate that carbon dioxide cooling, as well as methane changes to the source species for hydrogen, both lead to predicted increases in the upper thermospheric hydrogen density and that the response of hydrogen to greenhouse gases depends on the phase of the solar cycle. However, the effect of greenhouse gas doubling is not as large as the modeled solar cycle variability of thermospheric hydrogen. I will discuss results from these simulations and comparisons to observations.

  3. Local time variations of the Venusian hydrogen corona

    NASA Astrophysics Data System (ADS)

    Chaufray, J.-Y.; Bertaux, J.-L.; Quémerais, E.; Sulis, S.; Leblanc, F.

    2014-04-01

    Atomic hydrogen in the upper atmosphere of Venus is produced by chemical reactions involving hydrogen bearing molecules such as H2O. Due to its low mass, atomic hydrogen can reach high altitudes and become the dominant species in the Venusian exosphere. The density of atomic hydrogen retrieved by Pioneer Venus Orbiter from H+ measurement of the ion mass spectrometer indicated large diurnal variation of the hydrogen content with a peak of density near 4:00 local time (1). The large dayside/nightside ratio ~ 1000 was attributed to the wind system induced from temperature contrast. First dayside observations of the atomic hydrogen Lymanalpha resonant line performed by the UV spectrometer SPICAV (2) aboard Venus Express suggested a lower ratio ~ 30 between morning side and evening side (3). In this presentation, we will present several recent observations of the Venusian hydrogen corona obtained by SPICAV at different local times at nightside to investigate more accurately the diurnal variations of the Venusian hydrogen corona.

  4. Chemochromic Hydrogen Leak Detectors

    NASA Technical Reports Server (NTRS)

    Roberson, Luke; Captain, Janine; Williams, Martha; Smith, Trent; Tate, LaNetra; Raissi, Ali; Mohajeri, Nahid; Muradov, Nazim; Bokerman, Gary

    2009-01-01

    At NASA, hydrogen safety is a key concern for space shuttle processing. Leaks of any level must be quickly recognized and addressed due to hydrogen s lower explosion limit. Chemo - chromic devices have been developed to detect hydrogen gas in several embodiments. Because hydrogen is odorless and colorless and poses an explosion hazard, there is an emerging need for sensors to quickly and accurately detect low levels of leaking hydrogen in fuel cells and other advanced energy- generating systems in which hydrogen is used as fuel. The device incorporates a chemo - chromic pigment into a base polymer. The article can reversibly or irreversibly change color upon exposure to hydrogen. The irreversible pigment changes color from a light beige to a dark gray. The sensitivity of the pigment can be tailored to its application by altering its exposure to gas through the incorporation of one or more additives or polymer matrix. Furthermore, through the incorporation of insulating additives, the chemochromic sensor can operate at cryogenic temperatures as low as 78 K. A chemochromic detector of this type can be manufactured into any feasible polymer part including injection molded plastic parts, fiber-spun textiles, or extruded tapes. The detectors are simple, inexpensive, portable, and do not require an external power source. The chemochromic detectors were installed and removed easily at the KSC launch pad without need for special expertise. These detectors may require an external monitor such as the human eye, camera, or electronic detector; however, they could be left in place, unmonitored, and examined later for color change to determine whether there had been exposure to hydrogen. In one type of envisioned application, chemochromic detectors would be fabricated as outer layers (e.g., casings or coatings) on high-pressure hydrogen storage tanks and other components of hydrogen-handling systems to provide visible indications of hydrogen leaks caused by fatigue failures or

  5. Chromatographic hydrogen isotope separation

    DOEpatents

    Aldridge, Frederick T.

    1981-01-01

    Intermetallic compounds with the CaCu.sub.5 type of crystal structure, particularly LaNiCo.sub.4 and CaNi.sub.5, exhibit high separation factors and fast equilibrium times and therefore are useful for packing a chromatographic hydrogen isotope separation colum. The addition of an inert metal to dilute the hydride improves performance of the column. A large scale mutli-stage chromatographic separation process run as a secondary process off a hydrogen feedstream from an industrial plant which uses large volumes of hydrogen can produce large quantities of heavy water at an effective cost for use in heavy water reactors.

  6. Chromatographic hydrogen isotope separation

    DOEpatents

    Aldridge, F.T.

    Intermetallic compounds with the CaCu/sub 5/ type of crystal structure, particularly LaNiCo/sub 4/ and CaNi/sub 5/, exhibit high separation factors and fast equilibrium times and therefore are useful for packing a chromatographic hydrogen isotope separation column. The addition of an inert metal to dilute the hydride improves performance of the column. A large scale multi-stage chromatographic separation process run as a secondary process off a hydrogen feedstream from an industrial plant which uses large volumes of hydrogen cn produce large quantities of heavy water at an effective cost for use in heavy water reactors.

  7. Hydrogen isotopic fractionation during crystallization of the terrestrial magma ocean

    NASA Astrophysics Data System (ADS)

    Pahlevan, K.; Karato, S. I.

    2016-12-01

    Models of the Moon-forming giant impact extensively melt and partially vaporize the silicate Earth and deliver a substantial mass of metal to the Earth's core. The subsequent evolution of the terrestrial magma ocean and overlying vapor atmosphere over the ensuing 105-6 years has been largely constrained by theoretical models with remnant signatures from this epoch proving somewhat elusive. We have calculated equilibrium hydrogen isotopic fractionation between the magma ocean and overlying steam atmosphere to determine the extent to which H isotopes trace the evolution during this epoch. By analogy with the modern silicate Earth, the magma ocean-steam atmosphere system is often assumed to be chemically oxidized (log fO2 QFM) with the dominant atmospheric vapor species taken to be water vapor. However, the terrestrial magma ocean - having held metallic droplets in suspension - may also exhibit a much more reducing character (log fO2 IW) such that equilibration with the overlying atmosphere renders molecular hydrogen the dominant H-bearing vapor species. This variable - the redox state of the magma ocean - has not been explicitly included in prior models of the coupled evolution of the magma ocean-steam atmosphere system. We find that the redox state of the magma ocean influences not only the vapor speciation and liquid-vapor partitioning of hydrogen but also the equilibrium isotopic fractionation during the crystallization epoch. The liquid-vapor isotopic fractionation of H is substantial under reducing conditions and can generate measurable D/H signatures in the crystallization products but is largely muted in an oxidizing magma ocean and steam atmosphere. We couple equilibrium isotopic fractionation with magma ocean crystallization calculations to forward model the behavior of hydrogen isotopes during this epoch and find that the distribution of H isotopes in the silicate Earth immediately following crystallization represents an oxybarometer for the terrestrial

  8. A strong seasonal dependence in the Martian hydrogen exosphere

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, Dolon; Clarke, John T.; Bertaux, Jean-Loup; Chaufray, Jean-Yves; Mayyasi, Majd

    2015-10-01

    Hubble Space Telescope and Mars Express observed unexpected rapid changes in the Martian hydrogen exosphere involving a decrease in scattered Lyman α intensity in fall 2007 (solar longitude, Ls = 331°-345°). These changes detected were speculated to be a combination of seasonal variation and/or dust storms and lower atmospheric dynamics. Here we present Hubble Space Telescope observations of Mars in 2014 over a broad range of heliocentric distances and seasons (Ls = 138°-232°) which indicate a factor of ~3.5 change in Martian Lyman α brightness associated with a factor of ~5.4 variation of hydrogen escape flux in the absence of global dust storms and significant solar variability. We thus conclude that seasonal effects have a strong influence on the hydrogen exosphere, which in turn has major implications for the processes that control water supply to the Martian upper atmosphere and the history of water escape from Mars.

  9. Atmospheric Mining in the Outer Solar System: Resource Capturing, Storage, and Utilization

    NASA Technical Reports Server (NTRS)

    Palaszewski, Bryan

    2012-01-01

    Atmospheric mining in the outer solar system has been investigated as a means of fuel production for high energy propulsion and power. Fusion fuels such as Helium 3 (3He) and hydrogen can be wrested from the atmospheres of Uranus and Neptune and either returned to Earth or used in-situ for energy production. Helium 3 and hydrogen (deuterium, etc.) were the primary gases of interest with hydrogen being the primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of analyses were undertaken to investigate resource capturing aspects of atmospheric mining in the outer solar system. This included the gas capturing rate for hydrogen helium 4 and helium 3, storage options, and different methods of direct use of the captured gases. Additional supporting analyses were conducted to illuminate vehicle sizing and orbital transportation issues.

  10. Atmospheric Mining in the Outer Solar System: Resource Capturing, Storage, and Utilization

    NASA Technical Reports Server (NTRS)

    Palaszewski, Bryan

    2014-01-01

    Atmospheric mining in the outer solar system has been investigated as a means of fuel production for high energy propulsion and power. Fusion fuels such as helium 3 and hydrogen can be wrested from the atmospheres of Uranus and Neptune and either returned to Earth or used in-situ for energy production. Helium 3 and hydrogen (deuterium, etc.) were the primary gases of interest with hydrogen being the primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of analyses were undertaken to investigate resource capturing aspects of atmospheric mining in the outer solar system. This included the gas capturing rate for hydrogen helium 4 and helium 3, storage options, and different methods of direct use of the captured gases. Additional supporting analyses were conducted to illuminate vehicle sizing and orbital transportation issues.

  11. Thin film hydrogen sensor

    DOEpatents

    Lauf, R.J.; Hoffheins, B.S.; Fleming, P.H.

    1994-11-22

    A hydrogen sensor element comprises an essentially inert, electrically-insulating substrate having a thin-film metallization deposited thereon which forms at least two resistors on the substrate. The metallization comprises a layer of Pd or a Pd alloy for sensing hydrogen and an underlying intermediate metal layer for providing enhanced adhesion of the metallization to the substrate. An essentially inert, electrically insulating, hydrogen impermeable passivation layer covers at least one of the resistors, and at least one of the resistors is left uncovered. The difference in electrical resistances of the covered resistor and the uncovered resistor is related to hydrogen concentration in a gas to which the sensor element is exposed. 6 figs.

  12. Hydrogen storage compositions

    DOEpatents

    Li, Wen; Vajo, John J.; Cumberland, Robert W.; Liu, Ping

    2011-04-19

    Compositions for hydrogen storage and methods of making such compositions employ an alloy that exhibits reversible formation/deformation of BH.sub.4.sup.- anions. The composition includes a ternary alloy including magnesium, boron and a metal and a metal hydride. The ternary alloy and the metal hydride are present in an amount sufficient to render the composition capable of hydrogen storage. The molar ratio of the metal to magnesium and boron in the alloy is such that the alloy exhibits reversible formation/deformation of BH.sub.4.sup.- anions. The hydrogen storage composition is prepared by combining magnesium, boron and a metal to prepare a ternary alloy and combining the ternary alloy with a metal hydride to form the hydrogen storage composition.

  13. Hydrogen in germanium

    SciTech Connect

    Haller, E.E.

    1978-09-01

    Hydrogen is shown to form molecular acceptors and donors in pure germanium. Piezospectroscopy reveals that the hydrogen-related shallow donor D has non-tetrahedral symmetry. One hydrogen atom is incorporated in D as shown with an isotope shift in the donor ground state. Oxygen is also involved in the formation of D. The hole emission rates of two copper--hydrogen acceptor complexes were determined with Deep Level Transient Spectroscopy. They are e/sub 1//sup Cu-H/ = 1.5 x 10/sup 8/ T/sup 2/ exp (-.195 eV/kT) K/sup -2/ s/sup -1/ and e/sub 3//sup Cu-H/ = 5.0 x 10/sup 8/ T/sup 2/ exp (-.068/kT) K/sup -2/more » s/sup -1/.« less

  14. Remote hydrogen sensing techniques

    NASA Technical Reports Server (NTRS)

    Perry, Cortes L.

    1992-01-01

    The objective of this project is to evaluate remote hydrogen sensing methodologies utilizing metal oxide semi-conductor field effect transistors (MOS-FET) and mass spectrometric (MS) technologies and combinations thereof.

  15. Florida Hydrogen Initiative

    SciTech Connect

    Block, David L

    2013-06-30

    The Florida Hydrogen Initiative (FHI) was a research, development and demonstration hydrogen and fuel cell program. The FHI program objectives were to develop Florida?s hydrogen and fuel cell infrastructure and to assist DOE in its hydrogen and fuel cell activities The FHI program funded 12 RD&D projects as follows: Hydrogen Refueling Infrastructure and Rental Car Strategies -- L. Lines, Rollins College This project analyzes strategies for Florida's early stage adaptation of hydrogen-powered public transportation. In particular, the report investigates urban and statewide network of refueling stations and the feasibility of establishing a hydrogen rental-car fleet based in Orlando. Methanol Fuelmore » Cell Vehicle Charging Station at Florida Atlantic University ? M. Fuchs, EnerFuel, Inc. The project objectives were to design, and demonstrate a 10 kWnet proton exchange membrane fuel cell stationary power plant operating on methanol, to achieve an electrical energy efficiency of 32% and to demonstrate transient response time of less than 3 milliseconds. Assessment of Public Understanding of the Hydrogen Economy Through Science Center Exhibits, J. Newman, Orlando Science Center The project objective was to design and build an interactive Science Center exhibit called: ?H2Now: the Great Hydrogen Xchange?. On-site Reformation of Diesel Fuel for Hydrogen Fueling Station Applications ? A. Raissi, Florida Solar Energy Center This project developed an on-demand forecourt hydrogen production technology by catalytically converting high-sulfur hydrocarbon fuels to an essentially sulfur-free gas. The removal of sulfur from reformate is critical since most catalysts used for the steam reformation have limited sulfur tolerance. Chemochromic Hydrogen Leak Detectors for Safety Monitoring ? N. Mohajeri and N. Muradov, Florida Solar Energy Center This project developed and demonstrated a cost-effective and highly selective chemochromic (visual) hydrogen leak detector for safety

  16. Hydrogen-fueled engine

    NASA Technical Reports Server (NTRS)

    Laumann, E. A.; Reynolds, R. K. (Inventor)

    1978-01-01

    A hydrogen-oxygen fueled internal combustion engine is described, which utilizes an inert gas, such as argon, as a working fluid to increase the efficiency of the engine, eliminate pollution, and facilitate operation of a closed cycle energy system. In a system where sunlight or other intermittent energy source is available to separate hydrogen and oxygen from water, the oxygen and inert gas are taken into a diesel engine into which hydrogen is injected and ignited. The exhaust is cooled so that it contains only water and the inert gas. The inert gas in the exhaust is returned to the engine for use with fresh oxygen, while the water in the exhaust is returned to the intermittent energy source for reconversion to hydrogen and oxygen.

  17. Atmospheric reconnaissance of the habitable-zone Earth-sized planets orbiting TRAPPIST-1

    NASA Astrophysics Data System (ADS)

    de Wit, Julien; Wakeford, Hannah R.; Lewis, Nikole K.; Delrez, Laetitia; Gillon, Michaël; Selsis, Frank; Leconte, Jérémy; Demory, Brice-Olivier; Bolmont, Emeline; Bourrier, Vincent; Burgasser, Adam J.; Grimm, Simon; Jehin, Emmanuël; Lederer, Susan M.; Owen, James E.; Stamenković, Vlada; Triaud, Amaury H. M. J.

    2018-03-01

    Seven temperate Earth-sized exoplanets readily amenable for atmospheric studies transit the nearby ultracool dwarf star TRAPPIST-1 (refs 1,2). Their atmospheric regime is unknown and could range from extended primordial hydrogen-dominated to depleted atmospheres3-6. Hydrogen in particular is a powerful greenhouse gas that may prevent the habitability of inner planets while enabling the habitability of outer ones6-8. An atmosphere largely dominated by hydrogen, if cloud-free, should yield prominent spectroscopic signatures in the near-infrared detectable during transits. Observations of the innermost planets have ruled out such signatures9. However, the outermost planets are more likely to have sustained such a Neptune-like atmosphere10, 11. Here, we report observations for the four planets within or near the system's habitable zone, the circumstellar region where liquid water could exist on a planetary surface12-14. These planets do not exhibit prominent spectroscopic signatures at near-infrared wavelengths either, which rules out cloud-free hydrogen-dominated atmospheres for TRAPPIST-1 d, e and f, with significance of 8σ, 6σ and 4σ, respectively. Such an atmosphere is instead not excluded for planet g. As high-altitude clouds and hazes are not expected in hydrogen-dominated atmospheres around planets with such insolation15, 16, these observations further support their terrestrial and potentially habitable nature.

  18. Atmospheric Mining in the Outer Solar System:. [Aerial Vehicle Reconnaissance and Exploration Options

    NASA Technical Reports Server (NTRS)

    Palaszewski, Bryan A.

    2014-01-01

    Atmospheric mining in the outer solar system has been investigated as a means of fuel production for high energy propulsion and power. Fusion fuels such as Helium 3 (3He) and hydrogen can be wrested from the atmospheres of Uranus and Neptune and either returned to Earth or used in-situ for energy production. Helium 3 and hydrogen (deuterium, etc.) were the primary gases of interest with hydrogen being the primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of analyses were undertaken to investigate resource capturing aspects of atmospheric mining in the outer solar system. This included the gas capturing rate, storage options, and different methods of direct use of the captured gases. Additional supporting analyses were conducted to illuminate vehicle sizing and orbital transportation issues. While capturing 3He, large amounts of hydrogen and 4He are produced. With these two additional gases, the potential for fueling small and large fleets of additional exploration and exploitation vehicles exists. Additional aerospacecraft or other aerial vehicles (UAVs, balloons, rockets, etc.) could fly through the outer planet atmospheres, for global weather observations, localized storm or other disturbance investigations, wind speed measurements, polar observations, etc. Deep-diving aircraft (built with the strength to withstand many atmospheres of pressure) powered by the excess hydrogen or helium 4 may be designed to probe the higher density regions of the gas giants. Outer planet atmospheric properties, atmospheric storm data, and mission planning for future outer planet UAVs are presented.

  19. The hydrogen issue.

    PubMed

    Armaroli, Nicola; Balzani, Vincenzo

    2011-01-17

    Hydrogen is often proposed as the fuel of the future, but the transformation from the present fossil fuel economy to a hydrogen economy will need the solution of numerous complex scientific and technological issues, which will require several decades to be accomplished. Hydrogen is not an alternative fuel, but an energy carrier that has to be produced by using energy, starting from hydrogen-rich compounds. Production from gasoline or natural gas does not offer any advantage over the direct use of such fuels. Production from coal by gasification techniques with capture and sequestration of CO₂ could be an interim solution. Water splitting by artificial photosynthesis, photobiological methods based on algae, and high temperatures obtained by nuclear or concentrated solar power plants are promising approaches, but still far from practical applications. In the next decades, the development of the hydrogen economy will most likely rely on water electrolysis by using enormous amounts of electric power, which in its turn has to be generated. Producing electricity by burning fossil fuels, of course, cannot be a rational solution. Hydroelectric power can give but a very modest contribution. Therefore, it will be necessary to generate large amounts of electric power by nuclear energy of by renewable energies. A hydrogen economy based on nuclear electricity would imply the construction of thousands of fission reactors, thereby magnifying all the problems related to the use of nuclear energy (e.g., safe disposal of radioactive waste, nuclear proliferation, plant decommissioning, uranium shortage). In principle, wind, photovoltaic, and concentrated solar power have the potential to produce enormous amounts of electric power, but, except for wind, such technologies are too underdeveloped and expensive to tackle such a big task in a short period of time. A full development of a hydrogen economy needs also improvement in hydrogen storage, transportation and distribution

  20. Method of producing hydrogen

    DOEpatents

    Bingham, Dennis N.; Klingler, Kerry M.; Wilding, Bruce M.; Zollinger, William T.

    2006-12-26

    A method of producing hydrogen is disclosed and which includes providing a first composition; providing a second composition; reacting the first and second compositions together to produce a chemical hydride; providing a liquid and reacting the chemical hydride with the liquid in a manner to produce a high pressure hydrogen gas and a byproduct which includes the first composition; and reusing the first composition formed as a byproduct in a subsequent chemical reaction to form additional chemical hydride.

  1. Lokiarchaeon is hydrogen dependent.

    PubMed

    Sousa, Filipa L; Neukirchen, Sinje; Allen, John F; Lane, Nick; Martin, William F

    2016-04-04

    The nature of the host that acquired the mitochondrion at the eukaryote origin is an important microbial evolutionary issue. Modern phylogenetics indicates that the host was an archaeon. The metagenome sequence of Candidatus Lokiarchaeon has identified it as being the closest relative of the host yet known. Here, we report comparative genomic evidence indicating that Lokiarchaeon is hydrogen dependent, as one theory for the eukaryote origin-the hydrogen hypothesis-predicts for the host lineage.

  2. Purdue Hydrogen Systems Laboratory

    SciTech Connect

    Jay P Gore; Robert Kramer; Timothee L Pourpoint

    2011-12-28

    The Hydrogen Systems Laboratory in a unique partnership between Purdue University's main campus in West Lafayette and the Calumet campus was established and its capabilities were enhanced towards technology demonstrators. The laboratory engaged in basic research in hydrogen production and storage and initiated engineering systems research with performance goals established as per the USDOE Hydrogen, Fuel Cells, and Infrastructure Technologies Program. In the chemical storage and recycling part of the project, we worked towards maximum recycling yield via novel chemical selection and novel recycling pathways. With the basic potential of a large hydrogen yield from AB, we used it asmore » an example chemical but have also discovered its limitations. Further, we discovered alternate storage chemicals that appear to have advantages over AB. We improved the slurry hydrolysis approach by using advanced slurry/solution mixing techniques. We demonstrated vehicle scale aqueous and non-aqueous slurry reactors to address various engineering issues in on-board chemical hydrogen storage systems. We measured the thermal properties of raw and spent AB. Further, we conducted experiments to determine reaction mechanisms and kinetics of hydrothermolysis in hydride-rich solutions and slurries. We also developed a continuous flow reactor and a laboratory scale fuel cell power generation system. The biological hydrogen production work summarized as Task 4.0 below, included investigating optimal hydrogen production cultures for different substrates, reducing the water content in the substrate, and integrating results from vacuum tube solar collector based pre and post processing tests into an enhanced energy system model. An automated testing device was used to finalize optimal hydrogen production conditions using statistical procedures. A 3 L commercial fermentor (New Brunswick, BioFlo 115) was used to finalize testing of larger samples and to consider issues related to scale up

  3. Hydrogen recovery process

    DOEpatents

    Baker, Richard W.; Lokhandwala, Kaaeid A.; He, Zhenjie; Pinnau, Ingo

    2000-01-01

    A treatment process for a hydrogen-containing off-gas stream from a refinery, petrochemical plant or the like. The process includes three separation steps: condensation, membrane separation and hydrocarbon fraction separation. The membrane separation step is characterized in that it is carried out under conditions at which the membrane exhibits a selectivity in favor of methane over hydrogen of at least about 2.5.

  4. Nanostructured materials for hydrogen storage

    DOEpatents

    Williamson, Andrew J.; Reboredo, Fernando A.

    2007-12-04

    A system for hydrogen storage comprising a porous nano-structured material with hydrogen absorbed on the surfaces of the porous nano-structured material. The system of hydrogen storage comprises absorbing hydrogen on the surfaces of a porous nano-structured semiconductor material.

  5. Electrochemical hydrogen Storage Systems

    SciTech Connect

    Dr. Digby Macdonald

    2010-08-09

    As the global need for energy increases, scientists and engineers have found a possible solution by using hydrogen to power our world. Although hydrogen can be combusted as a fuel, it is considered an energy carrier for use in fuel cells wherein it is consumed (oxidized) without the production of greenhouse gases and produces electrical energy with high efficiency. Chemical storage of hydrogen involves release of hydrogen in a controlled manner from materials in which the hydrogen is covalently bound. Sodium borohydride and aminoborane are two materials given consideration as chemical hydrogen storage materials by the US Department of Energy.more » A very significant barrier to adoption of these materials as hydrogen carriers is their regeneration from 'spent fuel,' i.e., the material remaining after discharge of hydrogen. The U.S. Department of Energy (DOE) formed a Center of Excellence for Chemical Hydrogen Storage, and this work stems from that project. The DOE has identified boron hydrides as being the main compounds of interest as hydrogen storage materials. The various boron hydrides are then oxidized to release their hydrogen, thereby forming a 'spent fuel' in the form of a lower boron hydride or even a boron oxide. The ultimate goal of this project is to take the oxidized boron hydrides as the spent fuel and hydrogenate them back to their original form so they can be used again as a fuel. Thus this research is essentially a boron hydride recycling project. In this report, research directed at regeneration of sodium borohydride and aminoborane is described. For sodium borohydride, electrochemical reduction of boric acid and sodium metaborate (representing spent fuel) in alkaline, aqueous solution has been investigated. Similarly to literature reports (primarily patents), a variety of cathode materials were tried in these experiments. Additionally, approaches directed at overcoming electrostatic repulsion of borate anion from the cathode, not described in

  6. Earth’s Earliest Atmospheres

    PubMed Central

    Zahnle, Kevin; Schaefer, Laura; Fegley, Bruce

    2010-01-01

    Earth is the one known example of an inhabited planet and to current knowledge the likeliest site of the one known origin of life. Here we discuss the origin of Earth’s atmosphere and ocean and some of the environmental conditions of the early Earth as they may relate to the origin of life. A key punctuating event in the narrative is the Moon-forming impact, partly because it made Earth for a short time absolutely uninhabitable, and partly because it sets the boundary conditions for Earth’s subsequent evolution. If life began on Earth, as opposed to having migrated here, it would have done so after the Moon-forming impact. What took place before the Moon formed determined the bulk properties of the Earth and probably determined the overall compositions and sizes of its atmospheres and oceans. What took place afterward animated these materials. One interesting consequence of the Moon-forming impact is that the mantle is devolatized, so that the volatiles subsequently fell out in a kind of condensation sequence. This ensures that the volatiles were concentrated toward the surface so that, for example, the oceans were likely salty from the start. We also point out that an atmosphere generated by impact degassing would tend to have a composition reflective of the impacting bodies (rather than the mantle), and these are almost without exception strongly reducing and volatile-rich. A consequence is that, although CO- or methane-rich atmospheres are not necessarily stable as steady states, they are quite likely to have existed as long-lived transients, many times. With CO comes abundant chemical energy in a metastable package, and with methane comes hydrogen cyanide and ammonia as important albeit less abundant gases. PMID:20573713

  7. Hydrogen Materials Compatibility in Piezoelectrics

    NASA Astrophysics Data System (ADS)

    Alvine, Kyle; Pitman, Stan; Henager, Charles; Shutthanandan, Vaithiyalingam; Brown, Craig; Tyagi, Madhu; Jenkins, Tim; Udovic, Terry

    2010-03-01

    Hydrogen materials compatibility is an important materials science issue for hydrogen storage and delivery in hydrogen vehicle technology and infrastructure and to a lesser degree the microelectronics industry where hydrogen passivation is required. Piezoelectrics are one such material. They are used in direct injection hydrogen internal combustion engines (H2ICE) as actuators but tend to foul rapidly in high pressure hydrogen. Ferroelectric random access memory (FERAM) also suffers similar degradation issues. We present high pressure hydrogen absorption and diffusion findings for PZT and BaTiO3 piezoelectric materials. Data is based on quasi-elastic neutron (QENS) scattering and elastic recoil detection analysis (ERDA).

  8. Germanium detector passivated with hydrogenated amorphous germanium

    DOEpatents

    Hansen, William L.; Haller, Eugene E.

    1986-01-01

    Passivation of predominantly crystalline semiconductor devices (12) is provided for by a surface coating (21) of sputtered hydrogenated amorphous semiconductor material. Passivation of a radiation detector germanium diode, for example, is realized by sputtering a coating (21) of amorphous germanium onto the etched and quenched diode surface (11) in a low pressure atmosphere of hydrogen and argon. Unlike prior germanium diode semiconductor devices (12), which must be maintained in vacuum at cryogenic temperatures to avoid deterioration, a diode processed in the described manner may be stored in air at room temperature or otherwise exposed to a variety of environmental conditions. The coating (21) compensates for pre-existing undesirable surface states as well as protecting the semiconductor device (12) against future impregnation with impurities.

  9. Spectroscopy in the study of planetary atmospheres - Abundances from the visible region

    NASA Technical Reports Server (NTRS)

    Lutz, B. L.

    1978-01-01

    Spectrophotometric studies of three molecular constituents - hydrogen, methane, and ammonia - identified in the visible region of the spectra of the outer planets are reviewed. The history of quadrupole line observations for hydrogen molecules and the significance of the HD molecule for the dipole spectrum are considered. Approaches to quantitative estimates of methane concentration in planetary atmospheres are explained, and the detection of ammonia in the atmospheres of Jupiter and Saturn is described.

  10. Improved Hydrogen Gas Getters for TRU Waste -- Final Report

    SciTech Connect

    Mark Stone; Michael Benson; Christopher Orme

    2005-09-01

    Alpha radiolysis of hydrogenous waste and packaging materials generates hydrogen gas in radioactive storage containers. For that reason, the Nuclear Regulatory Commission limits the flammable gas (hydrogen) concentration in the Transuranic Package Transporter-II (TRUPACT-II) containers to 5 vol% of hydrogen in air, which is the lower explosion limit. Consequently, a method is needed to prevent the build up of hydrogen to 5 vol% during the storage and transport of the TRUPACT-II containers (up to 60 days). One promising option is the use of hydrogen getters. These materials scavenge hydrogen from the gas phase and irreversibly bind it in the solidmore » phase. One proven getter is a material called 1,4-bis (phenylethynyl) benzene, or DEB, characterized by the presence of carbon-carbon triple bonds. Carbon may, in the presence of suitable precious metal catalysts such as palladium, irreversibly react with and bind hydrogen. In the presence of oxygen, the precious metal may also eliminate hydrogen by catalyzing the formation of water. This reaction is called catalytic recombination. DEB has the needed binding rate and capacity for hydrogen that potentially could be generated in the TRUPACT II. Phases 1 and 2 of this project showed that uncoated DEB performed satisfactorily in lab scale tests. Based upon these results, Phase 3, the final project phase, included larger scale testing. Test vessels were scaled to replicate the ratio between void space in the inner containment vessel of a TRUPACT-II container and a payload of seven 55-gallon drums. The tests were run with an atmosphere of air for 63.9 days at ambient temperature (15-27°C) and a scaled hydrogen generation rate of 2.60E-07 moles per second (0.35 cc/min). A second type of getter known as VEI, a proprietary polymer hydrogen getter characterized by carbon-carbon double bonds, was also tested in Phase 3. Hydrogen was successfully “gettered” by both getter systems. Hydrogen concentrations remained below 5

  11. A Synergistic Approach to Interpreting Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Batalha, Natasha E.

    We will soon have the technological capability to measure the atmospheric composition of temperate Earth-sized planets orbiting nearby stars. Interpreting these atmospheric signals poses a new challenge to planetary science. In contrast to jovian-like atmospheres, whose bulk compositions consist of hydrogen and helium, terrestrial planet atmospheres are likely comprised of high mean molecular weight secondary atmospheres, which have gone through a high degree of evolution. For example, present-day Mars has a frozen surface with a thin tenuous atmosphere, but 4 billion years ago it may have been warmed by a thick greenhouse atmosphere. Several processes contribute to a planet's atmospheric evolution: stellar evolution, geological processes, atmospheric escape, biology, etc. Each of these individual processes affects the planetary system as a whole and therefore they all must be considered in the modeling of terrestrial planets. In order to demonstrate the intricacies in modeling terrestrial planets, I use early Mars as a case study. I leverage a combination of one-dimensional climate, photochemical and energy balance models in order to create one self-consistent model that closely matches currently available climate data. One-dimensional models can address several processes: the influence of greenhouse gases on heating, the effect of the planet's geological processes (i.e. volcanoes and the carbonatesilicate cycle) on the atmosphere, the effect of rainfall on atmospheric composition and the stellar irradiance. After demonstrating the number of assumptions required to build a model, I look towards what exactly we can learn from remote observations of temperate Earths and Super Earths. However, unlike in-situ observations from our own solar system, remote sensing techniques need to be developed and understood in order to accurately characterize exo-atmospheres. I describe the models used to create synthetic transit transmission observations, which includes models of

  12. Evolution of the atmosphere and oceans.

    PubMed

    Holland, H D; Lazar, B; McCaffrey, M

    1986-03-06

    The residence times of most constituents of the atmosphere and oceans are small fractions of the age of the Earth and, in general, their rate of output has been nearly equal to their rate of input. We are disturbing a number of these dynamic equilibria quite severely. The mineralogy of marine evaporites rules out drastic changes in the composition of sea water during the last 900 Myr. The chemistry of soils formed more than 1,000 Myr ago suggests that the atmosphere then contained significantly more CO2 and less O2 than at present. Hydrogen peroxide may well have been the principal oxidant and formaldehyde the main reductant in rain water between 3,000 and 1,000 Myr ago. Major changes in atmospheric chemistry since that time are almost certainly related to the evolution of the biosphere.

  13. Hydrogen storage and generation system

    DOEpatents

    Dentinger, Paul M.; Crowell, Jeffrey A. W.

    2010-08-24

    A system for storing and generating hydrogen generally and, in particular, a system for storing and generating hydrogen for use in an H.sub.2/O.sub.2 fuel cell. The hydrogen storage system uses the beta particles from a beta particle emitting material to degrade an organic polymer material to release substantially pure hydrogen. In a preferred embodiment of the invention, beta particles from .sup.63Ni are used to release hydrogen from linear polyethylene.

  14. Hydrogen transport through stainless steel under plasma irradiation

    NASA Astrophysics Data System (ADS)

    Airapetov, A. A.; Begrambekov, L. B.; Kaplevsky, A. S.; Sadovskiy, Ya A.

    2016-01-01

    The paper presents the results of investigation of gas exchange through stainless steel surface of the plasma chamber under irradiation with hydrogen atoms in oxygen atmosphere or oxygen contaminated hydrogen plasma. Dependence of this process on various irradiation parameters, such as the metal temperature, energy of irradiating ions, gas composition of plasma are studied. It is shown, that desorption from stainless steel is activated with the increase of the plasma chamber walls temperature and energy of irradiating ions. Hydrogen release occurs also under irradiation of the walls by helium and argon plasmas added with oxygen, however the amount of released hydrogen is several times lower than in the case of irradiation with oxygen contaminated deuterium plasma.

  15. Hydrogenation of anthraquinone on metal-containing catalysts

    SciTech Connect

    Lunin, V.V.; Markaryan, G.L.; Chetina, O.V.

    1982-12-01

    The present work studied the reaction of hydrogen activated on metal-containing catalysts (platinum black, Pt/Al/sub 2/O/sub 3/ (AP-15), and the hydride ZrNiH/sub 2.8/ with anthraquinone. The hydrogenation of anthraquinone bound into a strong donor-acceptor complex on the surface of Al/sub 2/O/sub 3/ and AP-15 and physically absorbed on silica gel was investigated. Results indicated that under conditions of mechanical mixing of silica gel with catalysts containing platinum or hydrides of intermetallic compounds in an atmosphere of hydrogen, anthraquinone physically adsorbed on silica gel is able to undergo hydrogenation at temperature above 100/sup 0/ C with formation of anthracene.

  16. Shuttle Gaseous Hydrogen Venting Risk from Flow Control Valve Failure

    NASA Technical Reports Server (NTRS)

    Drummond, J. Philip; Baurle, Robert A.; Gafney, Richard L.; Norris, Andrew T.; Pellett, Gerald L.; Rock, Kenneth E.

    2009-01-01

    This paper describes a series of studies to assess the potential risk associated with the failure of one of three gaseous hydrogen flow control valves in the orbiter's main propulsion system during the launch of Shuttle Endeavour (STS-126) in November 2008. The studies focused on critical issues associated with the possibility of combustion resulting from release of gaseous hydrogen from the external tank into the atmosphere during assent. The Shuttle Program currently assumes hydrogen venting from the external tank will result in a critical failure. The current effort was conducted to increase understanding of the risk associated with venting hydrogen given the flow control valve failure scenarios being considered in the Integrated In-Flight Anomaly Investigation being conducted by NASA.

  17. California Hydrogen Infrastructure Project

    SciTech Connect

    Heydorn, Edward C

    2013-03-12

    Air Products and Chemicals, Inc. has completed a comprehensive, multiyear project to demonstrate a hydrogen infrastructure in California. The specific primary objective of the project was to demonstrate a model of a real-world retail hydrogen infrastructure and acquire sufficient data within the project to assess the feasibility of achieving the nation's hydrogen infrastructure goals. The project helped to advance hydrogen station technology, including the vehicle-to-station fueling interface, through consumer experiences and feedback. By encompassing a variety of fuel cell vehicles, customer profiles and fueling experiences, this project was able to obtain a complete portrait of real market needs. The projectmore » also opened its stations to other qualified vehicle providers at the appropriate time to promote widespread use and gain even broader public understanding of a hydrogen infrastructure. The project engaged major energy companies to provide a fueling experience similar to traditional gasoline station sites to foster public acceptance of hydrogen. Work over the course of the project was focused in multiple areas. With respect to the equipment needed, technical design specifications (including both safety and operational considerations) were written, reviewed, and finalized. After finalizing individual equipment designs, complete station designs were started including process flow diagrams and systems safety reviews. Material quotes were obtained, and in some cases, depending on the project status and the lead time, equipment was placed on order and fabrication began. Consideration was given for expected vehicle usage and station capacity, standard features needed, and the ability to upgrade the station at a later date. In parallel with work on the equipment, discussions were started with various vehicle manufacturers to identify vehicle demand (short- and long-term needs). Discussions included identifying potential areas most suited for hydrogen fueling

  18. Atmospheric Effects of Energetic Electron Precipitation

    NASA Astrophysics Data System (ADS)

    Randall, C. E.; Harvey, V. L.; Peck, E. D.; Pettit, J.; Bardeen, C.; Kinnison, D. E.; Marsh, D. R.

    2016-12-01

    A comprehensive description of Sun-Earth connections requires quantifying the solar and magnetospheric energy input to the atmosphere. Energetic electron precipitation (EEP), is one of the primary processes by which the magnetosphere influences the atmosphere. The energy from EEP leads initially to the production of reactive odd nitrogen (NOx) and odd hydrogen (HOx), both of which react with ozone, a radiatively active gas. Through various dynamical and chemical processes, the absorbed energy is redistributed, and its effects amplified through such mechanisms as catalytic cycles and nonlinear wave/mean-flow interactions. Thus, EEP plays a critical role in driving the chemistry and potentially the radiative balance and circulation of the atmosphere. This talk summarizes recent calculations with the Whole Atmosphere Community Climate Model (WACCM) that were designed to investigate the effects of EEP on the atmosphere. The model was run both in its specified dynamics (SD) and free-running modes. In SD-WACCM the winds and temperatures are nudged to a reanalysis to constrain the meteorology in the troposphere and stratosphere, allowing for a more direct evaluation of the chemical response and a better comparison to observations. Results from the free-running simulations will be discussed in the context of both direct and indirect effects of EEP on the atmosphere. This talk will show comparisons of SD-WACCM output at the times and locations of satellite observations to the measurements themselves, as a means of evaluating the model results.

  19. On Nonequilibrium Radiation in Hydrogen Shock Layers

    NASA Technical Reports Server (NTRS)

    Park, Chul

    2005-01-01

    The influence of thermochemical nonequilibrium in the shock layer over a vehicle entering the atmosphere of an outer planet is examined qualitatively. The state of understanding of the heating environment for the Galileo Probe vehicle is first reviewed. Next, the possible reasons for the high recession in the frustum region and the low recession in the stagnation region are examined. The state of understanding of the nonequilibrium in the hydrogen flow is then examined. For the entry flight in Neptune, the possible influence of nonequilibrium is predicted.

  20. Hydrogen storage in spherical nanoporous carbons

    NASA Astrophysics Data System (ADS)

    Terrés, E.; Panella, B.; Hayashi, T.; Kim, Y. A.; Endo, M.; Dominguez, J. M.; Hirscher, M.; Terrones, H.; Terrones, M.

    2005-02-01

    We report H 2 storage capacities up to 2.7 wt% at 77 K in spherical nanoporous carbons exhibiting periodic arrays of pores and surface areas between 946 and 1646 m 2/g. The materials were produced via the pyrolysis of sucrose (C 12H 22O 11) embedded inside a spherical form of MCM-48 at 1000 °C in an inert atmosphere. Our results open up new possibilities for producing carbon nanomaterials with large surface areas, which are able to store hydrogen with attractive yields.

  1. The Jovian hydrogen bulge - Evidence for co-rotating magnetospheric convection

    NASA Technical Reports Server (NTRS)

    Dessler, A. J.; Sandel, B. R.; Atreya, S. K.

    1981-01-01

    The Jovian hydrogen bulge is located 180 deg away in the System II longitude from the active sector identified as the source region for Jupiter's decametric radio emission and release of energetic electrons into interplanetary space. The sector results from the large magnetic anomaly in the Jovian northern hemisphere; it is expected that a two-cell magnetospheric convection pattern is found in the Jovian atmosphere. The magnetic anomaly of the active sector produces a convection which brings the magnetospheric plasma to the upper atmosphere at the longitudes below the hydrogen bulge; the hot plasma contains electrons with energies of about 100 keV which dissociate atmospheric molecules into atomic hydrogen creating longitudinal symmetry in hydrogen Lyman alpha emission.

  2. Mass fractionation of noble gases in diffusion-limited hydrodynamic hydrogen escape

    NASA Astrophysics Data System (ADS)

    Zahnle, Kevin; Pollack, James B.; Kasting, James F.

    1990-04-01

    The theory of mass fractionation by hydrogen is presently extended to atmospheres in which hydrogen is not the major constituent. This theoretical framework is applied to three different cases. In the first, it is shown that the fractionation of terrestrial atmospheric neon with respect to mantle neon is explainable as a consequence of diffusion-limited hydrogen escape from a steam atmosphere toward the end of the accretion process. In the second, the anomalously high Ar-38/Ar-36 ratio of Mars is shown to be due to hydrodynamic fractionation by a vigorously escaping and very pure hydrogen wind. In the last case, it is speculated that the currently high Martian D/H ratio emerged during the hydrodynamic escape phase which fractionated Ar.

  3. Hot hydrogen testing of metallic turbo pump materials

    NASA Technical Reports Server (NTRS)

    Zee, Ralph; Chin, Bryan; Inamdar, Rohit

    1993-01-01

    The objectives of this investigation are to expose heat resistant alloys to hydrogen at elevated temperatures and to use various microstructural and analytical techniques to determine the chemical and rate process involved in degradation of these materials due to hydrogen environment. Inconel 718 and NASA-23 (wrought and cast) are candidate materials. The degradation of these materials in the presence of 1 to 5 atmospheric pressure of hydrogen from 450 C to 1100 C was examined. The hydrogen facility at Auburn University was used for this purpose. Control experiments were also conducted wherein the samples were exposed to vacuum so that a direct comparison of the results would separate the thermal contribution from the hydrogen effects. The samples were analyzed prior to and after exposure. A residual gas collection system was used to determine the gaseous species produced by any chemical reaction that may have occurred during the exposure. Analysis of this gas sample shows only the presence of H2 as expected. Analyses of the samples were conducted using optical microscopy, x-ray diffraction, scanning electron microscopy, and weight change. There appears to be no change in weight of the samples as a result of hydrogen exposure. In addition no visible change on the surface structure was detected. This indicates that the materials of interest do not have strong interaction with hot hydrogen. This is consistent with the microstructure results.

  4. Hydrogen Sulfide Production by Pseudomonas putrefaciens in Shrimp Experimentally Packed in Nitrogen1

    PubMed Central

    Lapin, R. M.; Koburger, J. A.

    1974-01-01

    Shrimp refrigerated in a nitrogen atmosphere develop off-odors not typical of normal spoilage. Investigations of this phenomenon showed that hydrogen sulfide developed in the headspace gas, and a large percentage of the microbial population present on the shrimp stored in nitrogen was capable of hydrogen sulfide production, in contrast to the flora on shrimp stored in air. The predominant hydrogen sulfide-producing organism, Pseudomonas putrefaciens, was present in low numbers on fresh shrimp but usually reached high numbers by day 8 of nitrogen storage. Further studies revealed that cysteine and cystine were the probable substrates in shrimp utilized by this organism for hydrogen sulfide production. When shrimp sterilized by irradiation were inoculated with P. putrefaciens and incubated in an atmosphere of nitrogen, hydrogen sulfide and the characteristic off-odors developed. PMID:4596748

  5. Safe Use of Hydrogen and Hydrogen Systems

    NASA Technical Reports Server (NTRS)

    Maes, Miguel

    2006-01-01

    This is a viewgraph presentation that is a course for teaching the safe use of hydrogen. The objectives of the course are 1. To familiarize the student with H2 safety properties 2. To enable the identification, evaluations and addressing of H2 system hazards 3. To teach: a. Safe practices for, b. Design, c. Materials selection, d. H2 system operation, e. Physical principles and empirical observations on which these safe practices are based, f. How to respond to emergency situations involving H2, g How to visualize safety concepts through in-class exercises, h. Identify numerous parameters important to H2 safety.

  6. Hot Hydrogen Test Facility

    NASA Astrophysics Data System (ADS)

    Swank, W. David; Carmack, Jon; Werner, James E.; Pink, Robert J.; Haggard, DeLon C.; Johnson, Ryan

    2007-01-01

    The core in a nuclear thermal rocket will operate at high temperatures and in hydrogen. One of the important parameters in evaluating the performance of a nuclear thermal rocket is specific impulse, ISP. This quantity is proportional to the square root of the propellant's absolute temperature and inversely proportional to square root of its molecular weight. Therefore, high temperature hydrogen is a favored propellant of nuclear thermal rocket designers. Previous work has shown that one of the life-limiting phenomena for thermal rocket nuclear cores is mass loss of fuel to flowing hydrogen at high temperatures. The hot hydrogen test facility located at the Idaho National Lab (INL) is designed to test suitability of different core materials in 2500°C hydrogen flowing at 1500 liters per minute. The facility is intended to test low activity uranium containing materials but is also suited for testing cladding and coating materials. In this first installment the facility is described. Automated data acquisition, flow and temperature control, vessel compatibility with various core geometries and overall capabilities are discussed.

  7. Hydrogen-selective membrane

    DOEpatents

    Collins, J.P.; Way, J.D.

    1995-09-19

    A hydrogen-selective membrane comprises a tubular porous ceramic support having a palladium metal layer deposited on an inside surface of the ceramic support. The thickness of the palladium layer is greater than about 10 {micro}m but typically less than about 20 {micro}m. The hydrogen permeation rate of the membrane is greater than about 1.0 moles/m{sup 2}s at a temperature of greater than about 500 C and a transmembrane pressure difference of about 1,500 kPa. Moreover, the hydrogen-to-nitrogen selectivity is greater than about 600 at a temperature of greater than about 500 C and a transmembrane pressure of about 700 kPa. Hydrogen can be separated from a mixture of gases using the membrane. The method may include the step of heating the mixture of gases to a temperature of greater than about 400 C and less than about 1000 C before the step of flowing the mixture of gases past the membrane. The mixture of gases may include ammonia. The ammonia typically is decomposed to provide nitrogen and hydrogen using a catalyst such as nickel. The catalyst may be placed inside the tubular ceramic support. The mixture of gases may be supplied by an industrial process such as the mixture of exhaust gases from the IGCC process. 9 figs.

  8. Hydrogen-selective membrane

    DOEpatents

    Collins, J.P.; Way, J.D.

    1997-07-29

    A hydrogen-selective membrane comprises a tubular porous ceramic support having a palladium metal layer deposited on an inside surface of the ceramic support. The thickness of the palladium layer is greater than about 10 {micro}m but typically less than about 20 {micro}m. The hydrogen permeation rate of the membrane is greater than about 1.0 moles/m{sup 2} s at a temperature of greater than about 500 C and a transmembrane pressure difference of about 1,500 kPa. Moreover, the hydrogen-to-nitrogen selectivity is greater than about 600 at a temperature of greater than about 500 C and a transmembrane pressure of about 700 kPa. Hydrogen can be separated from a mixture of gases using the membrane. The method may include the step of heating the mixture of gases to a temperature of greater than about 400 C and less than about 1000 C before the step of flowing the mixture of gases past the membrane. The mixture of gases may include ammonia. The ammonia typically is decomposed to provide nitrogen and hydrogen using a catalyst such as nickel. The catalyst may be placed inside the tubular ceramic support. The mixture of gases may be supplied by an industrial process such as the mixture of exhaust gases from the IGCC process. 9 figs.

  9. Hydrogen-selective membrane

    DOEpatents

    Collins, John P.; Way, J. Douglas

    1997-01-01

    A hydrogen-selective membrane comprises a tubular porous ceramic support having a palladium metal layer deposited on an inside surface of the ceramic support. The thickness of the palladium layer is greater than about 10 .mu.m but typically less than about 20 .mu.m. The hydrogen permeation rate of the membrane is greater than about 1.0 moles/m.sup.2. s at a temperature of greater than about 500.degree. C. and a transmembrane pressure difference of about 1,500 kPa. Moreover, the hydrogen-to-nitrogen selectivity is greater than about 600 at a temperature of greater than about 500.degree. C. and a transmembrane pressure of about 700 kPa. Hydrogen can be separated from a mixture of gases using the membrane. The method may include the step of heating the mixture of gases to a temperature of greater than about 400.degree. C. and less than about 1000.degree. C. before the step of flowing the mixture of gases past the membrane. The mixture of gases may include ammonia. The ammonia typically is decomposed to provide nitrogen and hydrogen using a catalyst such as nickel. The catalyst may be placed inside the tubular ceramic support. The mixture of gases may be supplied by an industrial process such as the mixture of exhaust gases from the IGCC process.

  10. Hydrogen-Selective Membrane

    DOEpatents

    Collins, John P.; Way, J. Douglas

    1995-09-19

    A hydrogen-selective membrane comprises a tubular porous ceramic support having a palladium metal layer deposited on an inside surface of the ceramic support. The thickness of the palladium layer is greater than about 10 .mu.m but typically less than about 20 .mu.m. The hydrogen permeation rate of the membrane is greater than about 1.0 moles/m.sup.2.s at a temperature of greater than about 500.degree. C. and a transmembrane pressure difference of about 1,500 kPa. Moreover, the hydrogen-to-nitrogen selectivity is greater than about 600 at a temperature of greater than about 500.degree. C. and a transmembrane pressure of about 700 kPa. Hydrogen can be separated from a mixture of gases using the membrane. The method may include the step of heating the mixture of gases to a temperature of greater than about 400.degree. C. and less than about 1000.degree. C. before the step of flowing the mixture of gases past the membrane. The mixture of gases may include ammonia. The ammonia typically is decomposed to provide nitrogen and hydrogen using a catalyst such as nickel. The catalyst may be placed inside the tubular ceramic support. The mixture of gases may be supplied by an industrial process such as the mixture of exhaust gases from the IGCC process.

  11. Flash and fire test: Evaluation of the behavior of nonmetallic materials in hydrogen

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Tests conducted to evaluate the behavior of nonmetallic materials in hydrogen are described. The results of the flash and fire test are presented. The flash and fire test is used to evaluate the tendency of heated materials to ignite in a hydrogen atmosphere when subjected to an ignition source. The test represents a hydrogen parallel to a hazard condition known to exist in oxygen systems. Ten nonmetallic materials were evaluated to establish baseline data on the behavior of the materials and to characterize one mode of material failure considered to be a factor pertinent to the safe use of a material in hydrogen.

  12. Hydrogen production from carbonaceous material

    DOEpatents

    Lackner, Klaus S.; Ziock, Hans J.; Harrison, Douglas P.

    2004-09-14

    Hydrogen is produced from solid or liquid carbon-containing fuels in a two-step process. The fuel is gasified with hydrogen in a hydrogenation reaction to produce a methane-rich gaseous reaction product, which is then reacted with water and calcium oxide in a hydrogen production and carbonation reaction to produce hydrogen and calcium carbonate. The calcium carbonate may be continuously removed from the hydrogen production and carbonation reaction zone and calcined to regenerate calcium oxide, which may be reintroduced into the hydrogen production and carbonation reaction zone. Hydrogen produced in the hydrogen production and carbonation reaction is more than sufficient both to provide the energy necessary for the calcination reaction and also to sustain the hydrogenation of the coal in the gasification reaction. The excess hydrogen is available for energy production or other purposes. Substantially all of the carbon introduced as fuel ultimately emerges from the invention process in a stream of substantially pure carbon dioxide. The water necessary for the hydrogen production and carbonation reaction may be introduced into both the gasification and hydrogen production and carbonation reactions, and allocated so as transfer the exothermic heat of reaction of the gasification reaction to the endothermic hydrogen production and carbonation reaction.

  13. The reaction process of hydrogen absorption and desorption on the nanocomposite of hydrogenated graphite and lithium hydride.

    PubMed

    Miyaoka, Hiroki; Ichikawa, Takayuki; Kojima, Yoshitsugu

    2009-05-20

    The lithium-carbon-hydrogen (Li-C-H) system is composed of hydrogenated nanostructural graphite (C(nano)Hx) and lithium hydride (LiH). C(nano)Hx is synthesized by ball-milling of graphite under a hydrogen atmosphere. In this work, the reaction process of hydrogen absorption and desorption on the Li-C-H system is investigated. The C(nano)Hx-LiH composite can desorb about 5.0 mass% of hydrogen at 350 degrees C with the formation of Li2C2 until the second cycle. However, the hydrogen desorption amount significantly decreases from the third cycle. Furthermore, it is shown by using gas chromatography that a considerable amount of hydrocarbons is desorbed during the rehydrogenation process. These results indicate that the amount of reaction between the polarized C-H groups in C(nano)Hx and LiH is reduced due to a decrease in the C-H groups by losing carbon atoms under the hydrogen absorption and desorption cycles.

  14. The Atmosphere of Venus

    NASA Technical Reports Server (NTRS)

    Hansen, J. E. (Editor)

    1975-01-01

    Topics considered at the conference included the dynamics, structure, chemistry, and evolution of the Venus atmosphere, as well as cloud physics and motion. Infrared, ultraviolet, and radio occultation methods of analysis are discussed, and atmospheric models are described.

  15. Rings Through Atmosphere

    NASA Image and Video Library

    2010-05-26

    NASA Cassini spacecraft looks toward the limb of Saturn and, on the right of this image, views part of the rings through the planet atmosphere. Saturn atmosphere can distort the view of the rings from some angles.

  16. Our shared atmosphere

    EPA Science Inventory

    Our atmosphere is a precious and fascinating resource, providing air to breath, shielding us from harmful ultraviolet radiation (UV), and maintaining a comfortable climate. Since the industrial revolution, people have significantly altered the composition of the atmosphere throu...

  17. Stellar atmospheric structural patterns

    NASA Technical Reports Server (NTRS)

    Thomas, R. N.

    1983-01-01

    The thermodynamics of stellar atmospheres is discussed. Particular attention is given to the relation between theoretical modeling and empirical evidence. The characteristics of distinctive atmospheric regions and their radical structures are discussed.

  18. Operations and maintenance manual, atmospheric contaminant sensor, revision B

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The sensor is a mass spectrometer system which continuously monitors the atmospheric constituents of hydrogen, water vapor, nitrogen, oxygen, and carbon dioxide, and monitors the Freons on a demand sampling basis. The manual provides a system description, operational procedures, and maintenance and troubleshooting instructions. Circuit diagrams are included.

  19. Operations and Maintenance Manual, Atmospheric Contaminant Sensor, Revision B.

    ERIC Educational Resources Information Center

    National Aeronautics and Space Administration, Washington, DC.

    The sensor is a mass spectrometer system which continuously monitors the atmospheric constituents of hydrogen, water vapor, nitrogen, oxygen, and carbon dioxide, and monitors the Freons on a demand sampling basis. The manual provides a system description, operational procedures, and maintenance and troubleshooting instructions. Circuit diagrams…

  20. Electrolytic synthesis of ammonia in molten salts under atmospheric pressure.

    PubMed

    Murakami, Tsuyoshi; Nishikiori, Tokujiro; Nohira, Toshiyuki; Ito, Yasuhiko

    2003-01-15

    Ammonia was successfully synthesized by using a new electrochemical reaction with high current efficiency at atmospheric pressure and at lower temperatures than the Haber-Bosch process. In this method, nitride ion (N3-), which is produced by the reduction from nitrogen gas at the cathode, is anodically oxidized and reacts with hydrogen to produce ammonia at the anode.

  1. Hydrogen: What's Different Now

    SciTech Connect

    Gearhart, Chris C

    2018-02-27

    This is an exciting time for hydrogen fuel-cell electric vehicles (FCEVs). They seem to be on the verge of a major market breakthrough. However, those of us who have been working in the hydrogen and FC industry for a while are familiar with the boom and bust cycle of FCEV hype-it feels like we have been here before. The first FC automobile was designed as far back as the 1960s. NASA was using FCs to power its spacecraft, and, in 1966, General Motors (GM) used this space-age technology in the prototype GM Electrovan. The Electrovan used the body and chassismore » of GM's Handivan, their production utility van at the time. The FC and hydrogen components for this vehicle filled nearly the entire available space of the van. At this point, FCs were clearly too expensive and impractical for production vehicles.« less

  2. Liquid Hydrogen Fill

    NASA Image and Video Library

    2016-08-03

    Inside a control building at NASA's Kennedy Space Center in Florida, Adam Swinger, cryogenic research engineer in the Exploration Research and Technology Directorate, communicates with team members during a test of the Ground Operations Demo Unit for liquid hydrogen. The system includes a 33,000 gallon liquid hydrogen storage tank with an internal cold heat exchanger supplied from a cryogenic refrigerator. The primary goal of the testing is to achieve a liquid hydrogen zero boil-off capability. The system was designed, installed and tested by a team of civil servants and contractors from the center's Cryogenic Test Laboratory, with support from engineers at NASA's Glenn Research Center in Cleveland and Stennis Space Center in Mississippi. It may be applicable for use by the Ground Systems Development and Operations Program at Launch Pad 39B.

  3. Liquid Hydrogen Fill

    NASA Image and Video Library

    2016-08-03

    Engineers complete a test of the Ground Operations Demo Unit for liquid hydrogen at NASA's Kennedy Space Center in Florida. The system includes a 33,000 gallon liquid hydrogen storage tank with an internal cold heat exchanger supplied from a cryogenic refrigerator. The primary goal of the testing is to achieve a liquid hydrogen zero boil-off capability. The system was designed, installed and tested by a team of civil servants and contractors from the center's Cryogenic Test Laboratory, with support from engineers at NASA's Glenn Research Center in Cleveland and Stennis Space Center in Mississippi. It may be applicable for use by the Ground Systems Development and Operations Program at Launch Pad 39B.

  4. The Galileo probe mass spectrometer: composition of Jupiter's atmosphere.

    PubMed

    Niemann, H B; Atreya, S K; Carignan, G R; Donahue, T M; Haberman, J A; Harpold, D N; Hartle, R E; Hunten, D M; Kasprzak, W T; Mahaffy, P R; Owen, T C; Spencer, N W; Way, S H

    1996-05-10

    The composition of the jovian atmosphere from 0.5 to 21 bars along the descent trajectory was determined by a quadrupole mass spectrometer on the Galileo probe. The mixing ratio of He (helium) to H2 (hydrogen), 0.156, is close to the solar ratio. The abundances of methane, water, argon, neon, and hydrogen sulfide were measured; krypton and xenon were detected. As measured in the jovian atmosphere, the amount of carbon is 2.9 times the solar abundance relative to H2, the amount of sulfur is greater than the solar abundance, and the amount of oxygen is much less than the solar abundance. The neon abundance compared with that of hydrogen is about an order of magnitude less than the solar abundance. Isotopic ratios of carbon and the noble gases are consistent with solar values. The measured ratio of deuterium to hydrogen (D/H) of (5 +/- 2) x 10(-5) indicates that this ratio is greater in solar-system hydrogen than in local interstellar hydrogen, and the 3He/4He ratio of (1.1 +/- 0.2) x 10(-4) provides a new value for protosolar (solar nebula) helium isotopes. Together, the D/H and 3He/4He ratios are consistent with conversion in the sun of protosolar deuterium to present-day 3He.

  5. Atmospheric Nitrogen Fluorescence Yield

    NASA Technical Reports Server (NTRS)

    Adams, J. H., Jr.; Christl, M. J.; Fountain, W. F.; Gregory, J. C.; Martens, K. U.; Sokolsky, Pierre; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Several existing and planned experiments estimate the energies of ultra-high energy cosmic rays from air showers using the atmospheric nitrogen fluorescence. The nitrogen fluorescence yield from air shower electrons depends on the atmospheric composition. We will discuss the uncertainties in the fluorescence yield form electrons in the real atmosphere and describe a concept for a small balloon payload to measure the atmospheric fluorescence yield as a function of attitude.

  6. Hydrogen production from microbial strains

    DOEpatents

    Harwood, Caroline S; Rey, Federico E

    2012-09-18

    The present invention is directed to a method of screening microbe strains capable of generating hydrogen. This method involves inoculating one or more microbes in a sample containing cell culture medium to form an inoculated culture medium. The inoculated culture medium is then incubated under hydrogen producing conditions. Once incubating causes the inoculated culture medium to produce hydrogen, microbes in the culture medium are identified as candidate microbe strains capable of generating hydrogen. Methods of producing hydrogen using one or more of the microbial strains identified as well as the hydrogen producing strains themselves are also disclosed.

  7. Understanding Microbial Contributions to Planetary Atmosphere

    NASA Technical Reports Server (NTRS)

    DesMarais, David J.

    2000-01-01

    Should our search of distant, extrasolar planetary atmospheres encounter evidence of life, that evidence will most likely be the gaseous products of microorganisms. Our biosphere was exclusively microbial for over 80 percent of its history and, even today, microbes strongly influence atmospheric composition. Life's greatest environmental impact arises from its capacity for harvesting energy and creating organic matter. Microorganisms catalyze the equilibration of C, S and transition metal species at temperatures where such reactions can be very slow in the absence of life. Sunlight has been harvested through photosynthesis to create enormous energy reservoirs that exist in the form of coexisting reservoirs of reduced, organic C and S stored in Earth's crust, and highly oxidized species (oxygen, sulfate and ferric iron) stored in the crust, oceans and atmosphere. Our civilization taps that storehouse of energy by burning fossil fuels. As astrobiologists, we identify the chemical consequences of distant biospheres as expressed in the atmospheres of their planets. Our approach must recognize that planets, biospheres and atmospheres evolve and change. For example, a tectonically more active early Earth hosted a thermophilic, non-photosynthetic biosphere and a mildly reducing, carbon dioxide-rich and oxygen-poor atmosphere. Microorganisms acquired energy by consuming hydrogen and sulfide and producing a broad array of reduced C and S gases, most notably, methane. Later, diverse types of bacterial photosynthesis developed that enhanced productivity but were incapable of splitting water to produce oxygen. Later, but still prior to 2.6 billion years ago, oxygenic photosynthesis developed. We can expect to encounter distant biospheres that represent various stages of evolution and that coexist with atmospheres ranging from mildly reducing to oxidizing compositions. Accordinaly, we must be prepared to interpret a broad range of atmospheric compositions, all containing

  8. NREL's Hydrogen Program

    SciTech Connect

    Deutsch, Todd; Sverdrup, George; Ghirardi, Maria

    2011-09-15

    The research and development taking place today at the National Renewable Energy Laboratory (NREL) is paving the way for nature's most plentiful element—hydrogen—to power the next generation. NREL researchers are working to unlock the potential of hydrogen and to advance the fuel cell technologies that will power the automobiles, equipment, and buildings of tomorrow. Hydrogen and fuel cells are a fundamental part of the broader portfolio of renewable technologies that are moving our nation toward its goals of energy independence and sustainability.

  9. Hydrogen Fire Imager

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The hand-held hydrogen fire imager was originally developed to 'see' the invisible flames of hydrogen and alcohol fires. It has also proven helpful for firefighters who fight conventional fires by allowing them to see through dense smoke, locate the seat of the fire, and image smoldering embers. NASA and Lockheed Martin engineers at Stennis Space Center invented the fire imager and invited fire department and industry representatives from the Mississippi Gulf Coast to a demonstration. Stennis Space Center's fire department set fire to an abandoned building on the test site to demonstrate how the imager works on visible fires.

  10. Thin film hydrogen sensor

    DOEpatents

    Cheng, Y.T.; Poli, A.A.; Meltser, M.A.

    1999-03-23

    A thin film hydrogen sensor includes a substantially flat ceramic substrate with first and second planar sides and a first substrate end opposite a second substrate end; a thin film temperature responsive resistor on the first planar side of the substrate proximate to the first substrate end; a thin film hydrogen responsive metal resistor on the first planar side of the substrate proximate to the fist substrate end and proximate to the temperature responsive resistor; and a heater on the second planar side of the substrate proximate to the first end. 5 figs.

  11. Thin film hydrogen sensor

    DOEpatents

    Cheng, Yang-Tse; Poli, Andrea A.; Meltser, Mark Alexander

    1999-01-01

    A thin film hydrogen sensor, includes: a substantially flat ceramic substrate with first and second planar sides and a first substrate end opposite a second substrate end; a thin film temperature responsive resistor on the first planar side of the substrate proximate to the first substrate end; a thin film hydrogen responsive metal resistor on the first planar side of the substrate proximate to the fist substrate end and proximate to the temperature responsive resistor; and a heater on the second planar side of the substrate proximate to the first end.

  12. Producing Hydrogen With Sunlight

    NASA Technical Reports Server (NTRS)

    Biddle, J. R.; Peterson, D. B.; Fujita, T.

    1987-01-01

    Costs high but reduced by further research. Producing hydrogen fuel on large scale from water by solar energy practical if plant costs reduced, according to study. Sunlight attractive energy source because it is free and because photon energy converts directly to chemical energy when it breaks water molecules into diatomic hydrogen and oxygen. Conversion process low in efficiency and photochemical reactor must be spread over large area, requiring large investment in plant. Economic analysis pertains to generic photochemical processes. Does not delve into details of photochemical reactor design because detailed reactor designs do not exist at this early stage of development.

  13. Hydrogen rich gas generator

    NASA Technical Reports Server (NTRS)

    Houseman, J.; Rupe, J. H.; Kushida, R. O. (Inventor)

    1976-01-01

    A process and apparatus is described for producing a hydrogen rich gas by injecting air and hydrocarbon fuel at one end of a cylindrically shaped chamber to form a mixture and igniting the mixture to provide hot combustion gases by partial oxidation of the hydrocarbon fuel. The combustion gases move away from the ignition region to another region where water is injected to be turned into steam by the hot combustion gases. The steam which is formed mixes with the hot gases to yield a uniform hot gas whereby a steam reforming reaction with the hydrocarbon fuel takes place to produce a hydrogen rich gas.

  14. Hydrogen peroxide catalytic decomposition

    NASA Technical Reports Server (NTRS)

    Parrish, Clyde F. (Inventor)

    2010-01-01

    Nitric oxide in a gaseous stream is converted to nitrogen dioxide using oxidizing species generated through the use of concentrated hydrogen peroxide fed as a monopropellant into a catalyzed thruster assembly. The hydrogen peroxide is preferably stored at stable concentration levels, i.e., approximately 50%-70% by volume, and may be increased in concentration in a continuous process preceding decomposition in the thruster assembly. The exhaust of the thruster assembly, rich in hydroxyl and/or hydroperoxy radicals, may be fed into a stream containing oxidizable components, such as nitric oxide, to facilitate their oxidation.

  15. Evidence for supersonic turbulence in the upper atmosphere of Jupiter.

    PubMed

    Emerich, C; Jaffel, L B; Clarke, J T; Prangé, R; Gladstone, G R; Sommeria, J; Ballester, G

    1996-08-23

    Spectra of the hydrogen Lyman alpha (Ly-alpha) emission line profiles of the jovian dayglow, obtained by the Goddard High Resolution Spectrograph on the Hubble Space Telescope, appear complex and variable on time scales of a few minutes. Dramatic changes occur in the Ly-alpha bulge region at low latitudes, where the line profiles exhibit structures that correspond to supersonic velocities of the order of several to tens of kilometers per second. This behavior, unexpected in a planetary atmosphere, is evidence for the particularly stormy jovian upper atmosphere, not unlike a star's atmosphere.

  16. MAVEN Imaging UV Spectrograph Results on the Mars Atmosphere and Atmospheric Escape

    NASA Astrophysics Data System (ADS)

    Chaffin, Michael; Schneider, Nick; McClintock, Bill; Stewart, Ian; Deighan, Justin; Jain, Sonal; Clarke, John; Holsclaw, Greg; Montmessin, Franck; Lefevre, Franck; Chaufray, Jean-Yves; Stiepen, Arnaud; Crismani, Matteo; Mayyasi, Majd; Evans, Scott; Stevens, Mike; Yelle, Roger; Jakosky, Bruce

    2016-04-01

    The Imaging Ultraviolet Spectrograph (IUVS) is one of nine science instruments aboard the Mars Atmosphere and Volatile and EvolutioN (MAVEN) spacecraft, whose payload is dedicated to exploring the upper atmosphere of Mars and understanding the magnitude and drivers of Mars' atmospheric escape rate. IUVS uses ultraviolet light to investigate the lower and upper atmosphere and ionosphere of Mars. The instrument is among the most powerful spectrographs sent to another planet, with several key capabilities: (1) separate Far-UV & Mid-UV channels for stray light control, (2) a high resolution echelle mode to resolve deuterium and hydrogen emission, (3) internal instrument pointing and scanning capabilities to allow complete mapping and nearly continuous operation, and (4) optimization for airglow studies. IUVS, along with other MAVEN instruments, obtains a comprehensive picture of the current state of the Mars upper atmosphere and ionosphere and the processes that control atmospheric escape. We present an overview of selected IUVS results, including (1) the discovery of diffuse aurora at Mars, and its contrast with previously detected discrete aurora localized near crustal magnetic fields; (2) widespread detection of mesospheric clouds; (3) Significant seasonal and short-timescale variability in thermospheric composition; (4) Global ozone maps spanning six months of seasonal evolution; and (5) mapping of the Mars H and O coronas, deriving the escape rates of H and O and their variability. This last is of particular importance for understanding the long term evolution of Mars and its atmosphere, with the observed preset escape of H potentially capable of removing a large fraction of Mars' initial water inventory, and the differential escape of O relative to H potentially providing a net source of oxidizing power to the atmosphere and planet at present, in contrast with a photochemical theory that predicts stoichiometrically balanced escape. The atmospheric and escape

  17. High-Yield Hydrogen Production from Starch and Water by a Synthetic Enzymatic Pathway

    PubMed Central

    Zhang, Y.-H. Percival; Evans, Barbara R.; Mielenz, Jonathan R.; Hopkins, Robert C.; Adams, Michael W.W.

    2007-01-01

    Background The future hydrogen economy offers a compelling energy vision, but there are four main obstacles: hydrogen production, storage, and distribution, as well as fuel cells. Hydrogen production from inexpensive abundant renewable biomass can produce cheaper hydrogen, decrease reliance on fossil fuels, and achieve zero net greenhouse gas emissions, but current chemical and biological means suffer from low hydrogen yields and/or severe reaction conditions. Methodology/Principal Findings Here we demonstrate a synthetic enzymatic pathway consisting of 13 enzymes for producing hydrogen from starch and water. The stoichiometric reaction is C6H10O5 (l)+7 H2O (l)→12 H2 (g)+6 CO2 (g). The overall process is spontaneous and unidirectional because of a negative Gibbs free energy and separation of the gaseous products with the aqueous reactants. Conclusions Enzymatic hydrogen production from starch and water mediated by 13 enzymes occurred at 30°C as expected, and the hydrogen yields were much higher than the theoretical limit (4 H2/glucose) of anaerobic fermentations. Significance The unique features, such as mild reaction conditions (30°C and atmospheric pressure), high hydrogen yields, likely low production costs ($∼2/kg H2), and a high energy-density carrier starch (14.8 H2-based mass%), provide great potential for mobile applications. With technology improvements and integration with fuel cells, this technology also solves the challenges associated with hydrogen storage, distribution, and infrastructure in the hydrogen economy. PMID:17520015

  18. Outer satellite atmospheres: Their nature and planetary interactions. [atmospheric models for Amalthea, Ganymede, Callisto, and Titan are presented

    NASA Technical Reports Server (NTRS)

    Smyth, W. H.

    1978-01-01

    Results show that Amalthea is likely to form a tightly-bound partial toroidal-shaped hydrogen cloud about its planet, while Ganymede, Callisto and Titan may have rather large, complete and nearly symmetric toroidal-shaped clouds. The toroidal cloud for Amalthea compares favorably with spacecraft data of Pioneer 10 for a satellite escape flux of order 10 to the 11th power atoms/sq cm/sec. Model results for Ganymede, Callisto and Titan suggest that these extended hydrogen atmospheres are likely to be detected by the Voyager spacecrafts and that Titan's cloud might also be detected by the Pioneer 11 spacecraft. Ions created because of atoms lost through ionization processes from these four extended hydrogen atmospheres and from the sodium cloud of Io are discussed.

  19. Hydrogen trapping and the interaction of hydrogen with metals

    NASA Technical Reports Server (NTRS)

    Danford, Merlin D.

    1987-01-01

    A method has been developed for the determination of trapped hydrogen in metal alloys, involving the determination of mobile hydrogen using the electrochemical method and the determination of total hydrogen with the fusion method, the difference in hydrogen concentrations being due to trapped hydrogen. It has been found that hydrogen enters body-centered cubic structures through the grain bodies rather than through the grain boundaries. Hydrogen also diffuses much more rapidly in body-centered cubic structures on charging than in face-centered cubic structures, the hydrogen distribution being more uniform in nature. The energy necessary to cause hydrogen embrittlement is postulated to arise from the changes in crystal lattice energies brought about through interaction of hydrogen with atoms in the metal lattice. The total energy change is more negative for body-centered cubic structures, believed to be the cause of a greater tendency toward hydrogen embrittlement. Finally, the agreement of hydrogen concentrations obtained at 25 C by the electrochemical method with those obtained by the fusion method are taken as a strong indication of the power and validity of the electrochemical method.

  20. Atmospheric Capture On Mars (and Processing)

    NASA Technical Reports Server (NTRS)

    Muscatello, Tony

    2017-01-01

    The ultimate destination of NASA's human exploration program is Mars. In Situ Resource Utilization (ISRU) is a key technology required to enable such missions, as first proposed by Prof. Robert Ash in 1976. This presentation will review progress in the systems required to produce rocket propellant, oxygen, and other consumables on Mars using the carbon dioxide atmosphere and other potential resources. For many years, NASA, commercial companies, and academia have been developing, and demonstrating techniques to capture and purify Martian atmospheric gases for their utilization for the production of hydrocarbons, oxygen, and water in ISRU systems. Other gases will be required to be separated from Martian atmospheric gases to provide pure CO2 for processing elements. Significant progress has been demonstrated in CO2 collection via adsorption by molecular sieves, freezing, and direct compression. Early stage work in adsorption in Ionic Liquids followed by electrolysis to oxygen is also underway. In addition, other Martian gases, such as nitrogen and argon, occur in concentrations high enough to be useful as buffer gas and could be captured as well. Gas separation requirements include, but are not limited to the selective separation of: (1) methane and water from unreacted carbon oxides (CO2-CO) and hydrogen typical of a Sabatier-type process, (2) carbon oxides and water from unreacted hydrogen from a Reverse Water-Gas Shift process, and (3) carbon oxides from oxygen from a trash/waste processing reaction.

  1. Isotopic transient tracing of the system isobutane-isobutene-hydrogen

    SciTech Connect

    Kao, Yuoyu.

    1989-01-01

    The question of whether a single rate determining step exists in the reversible reaction of isobutane dehydrogenation and isobutene hydrogenation over a chromia oxide gel catalyst was studied by means of isotopic transient tracing. It was found that reaction rate could be modeled by a single rate determining step, the abstraction of a hydrogen from the half-hydrogenated {sup *}i-C{sub 4}H{sub 9} surface intermediate or its reverse following a generally accepted Horiuti-Polanyi mechanism. By compartmental modeling, the remaining step velocities of the elementary steps were found to be very fast thus lending support to the assumption that they are. close tomore » equilibrium. In a separate D{sub 2}/i-C{sub 4}H{sub 10} exchange experiment, it was found the dissociative adsorption of isobutane is very fast and a large amount of hydrogen could be dissociatively adsorbed rapidly on the amorphous catalyst surface. The surface concentration of the adsorbed intermediates has also been estimated by C-13 transient tracing during the course of reaction. An overall hydrocarbon adsorption of 0.02-0.04 ml/g-catalyst was observed at about 350{degree}C and atmospheric pressure for both dehydrogenation and hydrogenation. It was found the {sup *}i-C{sub 4}H{sub 9} intermediate concentration is larger than that of {sup *}i-C{sub 4}H{sub 9} during dehydrogenation but smaller in the case of hydrogenation. By means of dynamic adsorption and H{sub 2} washing experiments, the surface hydrocarbon adsorption was also measured as about 0.03 ml/g-catalyst in the presence of hydrogen and about 0.08-0.11 ml/g-catalyst under a hydrogen free condition This suggests the possibility of site competition between hydrogen an hydrocarbons.« less

  2. Thermophysicochemical Reaction of ZrCo-Hydrogen-Helium System

    NASA Astrophysics Data System (ADS)

    Jung, Kwangjin; Kang, Hee-Seok; Yun, Sei-Hun; Chung, Hongsuk

    2017-11-01

    Nuclear fusion energy, which is clean and infinite, has been studied for more than half a century. Efforts are in progress worldwide for the demonstration and validation of nuclear fusion energy. Korea has been developing hydrogen isotope storage and delivery system (SDS) technologies including a basic scientific study on a hydrogen storage medium. An SDS bed, which is a key component of the SDS, is used for storing hydrogen isotopes in a metal hydride form and supplying them to a tokamak. Thermophysicochemical properties of the ZrCo-H2-He system are investigated for the practical utilization of a hydriding alloy system. The hydriding reaction, in which ZrCoHx is composed as ZrCo absorbing hydrogen, is exothermic. The dehydriding reaction, in which ZrCoHx decomposes into ZrCo and hydrogen, is endothermic. The heat generated through the hydriding reaction interrupts the hydriding progress. The heat loss by a dehydriding reaction impedes the dehydriding progress. The tritium decay product, helium-3, covers the ZrCo and keeps the hydrogen from contact with ZrCo in the SDS bed. In this study, we designed and fabricated a ZrCo bed and its performance test rig. The helium blanketing effect on a ZrCo hydrogen reaction with 0 % to 20 % helium content in a gaseous phase and a helium blanket removal method were studied experimentally. In addition, the volumetric flow rates and temperature at the beginning of a ZrCo hydrogen reaction in a hydrogen or helium atmosphere, and the cooling of the SDS bed by radiation only and by both radiation and natural convection related to the reuse cycle, were obtained.

  3. Hydrogen production using hydrogenase-containing oxygenic photosynthetic organisms

    DOEpatents

    Melis, Anastasios; Zhang, Liping; Benemann, John R.; Forestier, Marc; Ghirardi, Maria; Seibert, Michael

    2006-01-24

    A reversible physiological process provides for the temporal separation of oxygen evolution and hydrogen production in a microorganism, which includes the steps of growing a culture of the microorganism in medium under illuminated conditions to accumulate an endogenous substrate, depleting from the medium a nutrient selected from the group consisting of sulfur, iron, and/or manganese, sealing the culture from atmospheric oxygen, incubating the culture in light whereby a rate of light-induced oxygen production is equal to or less than a rate of respiration, and collecting an evolved gas. The process is particularly useful to accomplish a sustained photobiological hydrogen gas production in cultures of microorganisms, such as Chlamydomonas reinhardtii.

  4. Hydrogen Production Using Hydrogenase-Containing Oxygenic Photosynthetic Organisms

    DOEpatents

    Melis, A.; Zhang, L.; Benemann, J. R.; Forestier, M.; Ghirardi, M.; Seibert, M.

    2006-01-24

    A reversible physiological process provides for the temporal separation of oxygen evolution and hydrogen production in a microorganism, which includes the steps of growing a culture of the microorganism in medium under illuminated conditions to accumulate an endogenous substrate, depleting from the medium a nutrient selected from the group consisting of sulfur, iron, and/or manganese, sealing the culture from atmospheric oxygen, incubating the culture in light whereby a rate of light-induced oxygen production is equal to or less than a rate of respiration, and collecting an evolved gas. The process is particularly useful to accomplish a sustained photobiological hydrogen gas production in cultures of microorganisms, such as Chlamydomonas reinhardtii.

  5. Process for thermochemically producing hydrogen

    DOEpatents

    Bamberger, Carlos E.; Richardson, Donald M.

    1976-01-01

    Hydrogen is produced by the reaction of water with chromium sesquioxide and strontium oxide. The hydrogen producing reaction is combined with other reactions to produce a closed chemical cycle for the thermal decomposition of water.

  6. Onboard hydrogen generation for automobiles

    NASA Technical Reports Server (NTRS)

    Houseman, J.; Cerini, D. J.

    1976-01-01

    Problems concerning the use of hydrogen as a fuel for motor vehicles are related to the storage of the hydrogen onboard a vehicle. The feasibility is investigated to use an approach based on onboard hydrogen generation as a means to avoid these storage difficulties. Two major chemical processes can be used to produce hydrogen from liquid hydrocarbons and methanol. In steam reforming, the fuel reacts with water on a catalytic surface to produce a mixture of hydrogen and carbon monoxide. In partial oxidation, the fuel reacts with air, either on a catalytic surface or in a flame front, to yield a mixture of hydrogen and carbon monoxide. There are many trade-offs in onboard hydrogen generation, both in the choice of fuels as well as in the choice of a chemical process. Attention is given to these alternatives, the results of some experimental work in this area, and the combustion of various hydrogen-rich gases in an internal combustion engine.

  7. A Simple Hydrogen Electrode

    ERIC Educational Resources Information Center

    Eggen, Per-Odd

    2009-01-01

    This article describes the construction of an inexpensive, robust, and simple hydrogen electrode, as well as the use of this electrode to measure "standard" potentials. In the experiment described here the students can measure the reduction potentials of metal-metal ion pairs directly, without using a secondary reference electrode. Measurements…

  8. Resistive hydrogen sensing element

    DOEpatents

    Lauf, Robert J.

    2000-01-01

    Systems and methods are described for providing a hydrogen sensing element with a more robust exposed metallization by application of a discontinuous or porous overlay to hold the metallization firmly on the substrate. An apparatus includes: a substantially inert, electrically-insulating substrate; a first Pd containing metallization deposited upon the substrate and completely covered by a substantially hydrogen-impermeable layer so as to form a reference resistor on the substrate; a second Pd containing metallization deposited upon the substrate and at least a partially accessible to a gas to be tested, so as to form a hydrogen-sensing resistor; a protective structure disposed upon at least a portion of the second Pd containing metallization and at least a portion of the substrate to improve the attachment of the second Pd containing metallization to the substrate while allowing the gas to contact said the second Pd containing metallization; and a resistance bridge circuit coupled to both the first and second Pd containing metallizations. The circuit determines the difference in electrical resistance between the first and second Pd containing metallizations. The hydrogen concentration in the gas may be determined. The systems and methods provide advantages because adhesion is improved without adversely effecting measurement speed or sensitivity.

  9. Galactic Halos of Hydrogen

    NASA Image and Video Library

    2005-07-25

    This image shows two companion galaxies, NGC 4625 top and NGC 4618 bottom, and their surrounding cocoons of cool hydrogen gas purple. The huge set of spiral arms on NGC 4625 blue was discovered by the ultraviolet eyes of NASA GALEX.

  10. Liquid hydrogen sphere project

    NASA Image and Video Library

    2011-06-22

    A 107,000-gallon liquid hydrogen sphere no longer needed at Stennis Space Center is barged through the facility locks June 21. The rocket engine test facility has teamed with the Mississippi Department of Marine Resource to place the sphere in offshore waters as an artificial reef.

  11. Silver hydrogen batteries

    NASA Technical Reports Server (NTRS)

    Holleck, G.

    1978-01-01

    The feasibility of silver hydrogen batteries was investigated. Cell configurations and cell cycling were discussed. Energy density was found to be 65 to 100 watt hours per kilogram. Electrolyte management was considered critical to the cell's performance. Factors of electrolyte management which were particularly important were: (1) the nature of the separator system, and (2) the amount of electrolyte.

  12. Modified Hydrogen Balloon Explosion.

    ERIC Educational Resources Information Center

    Lawrence, Stephen S.

    1995-01-01

    Describes the technique of exploding an oxygen-hydrogen balloon using two balloons and having students observe the formation of water droplets. Suggests that the Socratic Method can be used to start discussions related to stochiometry, states of matter, and gas laws. (DDR)

  13. Photoelectrochemical hydrogen production

    SciTech Connect

    Rocheleau, R.E.; Miller, E.; Misra, A.

    1996-10-01

    The large-scale production of hydrogen utilizing energy provided by a renewable source to split water is one of the most ambitious long-term goals of the U.S. Department of Energy`s Hydrogen Program. One promising option to meet this goal is direct photoelectrolysis in which light absorbed by semiconductor-based photoelectrodes produces electrical power internally to split water into hydrogen and oxygen. Under this program, direct solar-to-chemical conversion efficiencies as high as 7.8 % have been demonstrated using low-cost, amorphous-silicon-based photoelectrodes. Detailed loss analysis models indicate that solar-to-chemical conversion greater than 10% can be achieved with amorphous-silicon-based structures optimized for hydrogen production. Inmore » this report, the authors describe the continuing progress in the development of thin-film catalytic/protective coatings, results of outdoor testing, and efforts to develop high efficiency, stable prototype systems.« less

  14. Hydrogen fuel - Universal energy

    NASA Astrophysics Data System (ADS)

    Prince, A. G.; Burg, J. A.

    The technology for the production, storage, transmission, and consumption of hydrogen as a fuel is surveyed, with the physical and chemical properties of hydrogen examined as they affect its use as a fuel. Sources of hydrogen production are described including synthesis from coal or natural gas, biomass conversion, thermochemical decomposition of water, and electrolysis of water, of these only electrolysis is considered economicially and technologically feasible in the near future. Methods of production of the large quantities of electricity required for the electrolysis of sea water are explored: fossil fuels, hydroelectric plants, nuclear fission, solar energy, wind power, geothermal energy, tidal power, wave motion, electrochemical concentration cells, and finally ocean thermal energy conversion (OTEC). The wind power and OTEC are considered in detail as the most feasible approaches. Techniques for transmission (by railcar or pipeline), storage (as liquid in underwater or underground tanks, as granular metal hydride, or as cryogenic liquid), and consumption (in fuel cells in conventional power plants, for home usage, for industrial furnaces, and for cars and aircraft) are analyzed. The safety problems of hydrogen as a universal fuel are discussed, noting that they are no greater than those for conventional fuels.

  15. Hydrogen isotope separation

    DOEpatents

    Bartlit, J.R.; Denton, W.H.; Sherman, R.H.

    Disclosed is a system of four cryogenic fractional distillation columns interlinked with two equilibrators for separating a DT and hydrogen feed stream into four product streams, consisting of a stream of high purity D/sub 2/, DT, T/sub 2/, and a tritium-free stream of HD for waste disposal.

  16. Hydrogen isotope separation

    DOEpatents

    Bartlit, John R.; Denton, William H.; Sherman, Robert H.

    1982-01-01

    A system of four cryogenic fractional distillation columns interlinked with two equilibrators for separating a DT and hydrogen feed stream into four product streams, consisting of a stream of high purity D.sub.2, DT, T.sub.2, and a tritium-free stream of HD for waste disposal.

  17. Hydrogen production by photosynthesis

    SciTech Connect

    Greenbaum, E.

    1981-01-01

    The photoevolution of hydrogen and oxygen by photosynthesis is an approach to the problem of solar energy conversion. This presentation is concerned with the roles of Photosystem II and the electron transport chain of photosynthesis in providing reducing equivalents which are eventually evolved as molecular hydrogen. Experimental data are presented on two systems which are capable of simultaneous photoproduction of molecular hydrogen and oxyen. The first is a green algal system. The second is a non-living cell-free system comprised of isolated chloroplasts, ferredoxin, and hydrogenase. Experiments have been performed which suggest that both the reducing side of Photosystem II asmore » well as endogenous reductants R (interacting directly with the electron transport chain) can provide electrons which are evolved as molecular hydrogen. These data suggest that the photochemical machinery of photosynthesis can be used to perform true photosynthetic water splitting, i.e., 2H/sub 2/O ..-->.. 2H/sub 2//sup +/O/sub 2/. The first experiments were performed on the CFH system using the technique of single turnover saturating flashes of light. This is a powerful method for studying the kinetic and mechanistic aspects of photoreactions. The preliminary results with this technique suggest that the turnover kinetics of the CFH system are relatively fast and comparable to that of normal photosynthesis. However, it appears that the number of functional photosynthetic units is relatively low as determined by the standard Emerson and Arnold Unit for normal photosynthesis.« less

  18. Hydrogen production from coal

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The gasification reactions necessary for the production of hydrogen from montana subbituminous coal are presented. The coal composition is given. The gasifier types mentioned include: suspension (entrained) combustion; fluidized bed; and moving bed. Each gasification process is described. The steam-iron process, raw and product gas compositions, gasifier feed quantities, and process efficiency evaluations are also included.

  19. Microwave plasma torches used for hydrogen production

    NASA Astrophysics Data System (ADS)

    Dias, F. M.; Bundaleska, N.; Henriques, J.; Tatarova, E.; Ferreira, C. M.

    2014-06-01

    A microwave plasma torch operating at 2.45 GHz and atmospheric pressure has been used as a medium and a tool for decomposition of alcohol in order to produce molecular hydrogen. Plasma in a gas mixture of argon and ethanol/methanol, with or without water, has been created using a waveguide surfatron launcher and a microwave generator delivering a power in the range 0.2-2.0 kW. Mass, Fourier Transform Infrared, and optical emission spectrometry have been applied as diagnostic tools. The decomposition yield of methanol was nearly 100 % with H2, CO, CO2, H2O, and solid carbon as the main reaction products. The influence of the fraction of Ar flow through the liquid ethanol/methanol on H2, CO, and CO2 partial pressures has been investigated, as well as the dependence of the produced H2 flow on the total flow and power. The optical emission spectrum in the range 250-700 nm has also been detected. There is a decrease of the OH(A-X) band intensity with the increase of methanol in the mixture. The emission of carbon atoms in the near UV range (240-300 nm) exhibits a significant increase as the amount of alcohol in the mixture grows. The obtained results clearly show that this microwave plasma torch at atmospheric pressure provides an efficient plasma environment for hydrogen production.

  20. Detroit Commuter Hydrogen Project

    SciTech Connect

    Brooks, Jerry; Prebo, Brendan

    2010-07-31

    This project was undertaken to demonstrate the viability of using hydrogen as a fuel in an internal combustion engine vehicle for use as a part of a mass transit system. The advantages of hydrogen as a fuel include renew-ability, minimal environmental impact on air quality and the environment, and potential to reduce dependence on foreign energy sources for the transportation sector. Recognizing the potential for the hydrogen fuel concept, the Southeast Michigan Congress of Governments (SEMCOG) determined to consider it in the study of a proposed regional mass transit rail system for southeast Michigan. SEMCOG wanted to evaluate the feasibilitymore » of using hydrogen fueled internal combustion engine (H2ICE) vehicles in shuttle buses to connect the Detroit Metro Airport to a proposed, nearby rail station. Shuttle buses are in current use on the airport for passenger parking and inter-terminal transport. This duty cycle is well suited to the application of hydrogen fuel at this time because of the ability to re-fuel vehicles at a single nearby facility, overcoming the challenge of restricted fuel availability in the undeveloped hydrogen fuel infrastructure. A cooperative agreement between SEMCOG and the DOE was initiated and two H2ICE buses were placed in regular passenger service on March 29, 2009 and operated for six months in regular passenger service. The buses were developed and built by the Ford Motor Company. Wayne County Airport Authority provided the location for the demonstration with the airport transportation contractor, Metro Cars Inc. operating the buses. The buses were built on Ford E450 chassis and incorporated a modified a 6.8L V-10 engine with specially designed supercharger, fuel rails and injectors among other sophisticated control systems. Up to 30 kg of on-board gaseous hydrogen were stored in a modular six tank, 350 bar (5000 psi) system to provide a 150 mile driving range. The bus chassis and body were configured to carry nine passengers

  1. Catalytic glycerol steam reforming for hydrogen production

    SciTech Connect

    Dan, Monica, E-mail: monica.dan@itim-cj.ro; Mihet, Maria, E-mail: maria.mihet@itim-cj.ro; Lazar, Mihaela D., E-mail: diana.lazar@itim-cj.ro

    2015-12-23

    Hydrogen production from glycerol by steam reforming combine two major advantages: (i) using glycerol as raw material add value to this by product of bio-diesel production which is obtained in large quantities around the world and have a very limited utilization now, and (ii) by implication of water molecules in the reaction the efficiency of hydrogen generation is increased as each mol of glycerol produces 7 mol of H{sub 2}. In this work we present the results obtained in the process of steam reforming of glycerol on Ni/Al{sub 2}O{sub 3}. The catalyst was prepared by wet impregnation method and characterizedmore » through different methods: N{sub 2} adsorption-desorption, XRD, TPR. The catalytic study was performed in a stainless steel tubular reactor at atmospheric pressure by varying the reaction conditions: steam/carbon ratio (1-9), gas flow (35 ml/min -133 ml/min), temperature (450-650°C). The gaseous fraction of the reaction products contain: H{sub 2}, CH{sub 4}, CO, CO{sub 2}. The optimum reaction conditions as resulted from this study are: temperature 550°C, Gly:H{sub 2}O ratio 9:1 and Ar flow 133 ml/min. In these conditions the glycerol conversion to gaseous products was 43% and the hydrogen yield was 30%.« less

  2. Hydrogen Fire Spectroscopy Issues Project

    NASA Technical Reports Server (NTRS)

    Youngquist, Robert C. (Compiler)

    2014-01-01

    The detection of hydrogen fires is important to the aerospace community. The National Aeronautics and Space Administration (NASA) has devoted significant effort to the development, testing, and installation of hydrogen fire detectors based on ultraviolet, near-infrared, mid-infrared, andor far-infrared flame emission bands. Yet, there is no intensity calibrated hydrogen-air flame spectrum over this range in the literature and consequently, it can be difficult to compare the merits of different radiation-based hydrogen fire detectors.

  3. Kinetics of hydrogen desorption from MgH2 and AlH3 hydrides

    NASA Astrophysics Data System (ADS)

    Terent'ev, P. B.; Gerasimov, E. G.; Mushnikov, N. V.; Uimin, M. A.; Maikov, V. V.; Gaviko, V. S.; Golovatenko, V. D.

    2015-12-01

    Kinetic parameters of the process of thermal decomposition of the MgH2 hydride (obtained by the method of the mechanoactivation of magnesium in a hydrogen atmosphere) and of the commercial AlH3 hydride have been studied upon the rapid heating in the range of temperatures of 150-510°C at hydrogen pressures of 0-2 atm. The time dependences of the amount of hydrogen released by the metal hydrides at different temperatures and pressures have been determined. It has been shown that the activation energies of the hydrogen desorption are 135 kJ/mol for MgH2 and 107 kJ/mol for AlH3. The maximum rates of hydrogen desorption from the investigated metal hydrides have been established, and the temperatures and initial pressures that ensure the maximum rate and maximum volume of the hydrogen release have been determined.

  4. Carbon Monoxide Affecting Planetary Atmospheric Chemistry

    NASA Astrophysics Data System (ADS)

    He, Chao; Horst, Sarah

    2016-10-01

    Atmospheric hazes are present in a range of solar system and extrasolar planetary atmospheres, and organic hazes, such as that in Titan's atmosphere, could be a source of prebiotic molecules.1 However, the chemistry occurring in planetary atmospheres and the resulting chemical structures are still not clear. Numerous experimental simulations2 have been carried out in the laboratory to understand the chemistry in N2/CH4 atmospheres, but very few simulations4 have included CO in their initial gas mixtures, which is an important component in many N2/CH4 atmospheres including Titan, Triton, and Pluto.3 Here we have conducted a series of atmosphere simulation experiments using AC glow discharge (cold plasma) as energy source to irradiate reactions in gas mixtures of CO, CH4, and N2 with a range of CO mixing ratios (from 0, 0.05%, 0.2%, 0.5%, 1%, 2.5%, to 5%) at low temperature (~100 K). Gas phase products are monitored during the reaction by quadrupole mass spectrometer (MS), and solid phase products are analyzed by solution-state nuclear magnetic resonance spectroscopy (NMR). MS results show that with the increase of CO in the initial gases, the production of nitrogenous organic molecules increases while the production of hydrogen molecules decreases in the gas phase. NMR measurements of the solid phase products show that with the increase of CO, hydrogen atoms bonded to nitrogen or oxygen in unsaturated structures increase while those bonded to saturated carbon decrease, which means more unsaturated species and less saturated species formed with the addition of CO. MS and NMR results demonstrate that the inclusion of CO affects the compositions of both gas and solid phase products, indicating that CO has an important impact on the chemistry occurring in our experiments and probably in planetary atmospheres.1. Hörst, S. M., et al. 2012, AsBio, 12, 8092. Cable, M. L., et al. 2012, Chem. Rev., 112, 18823. Lutz, B. L., et al. 1983, Sci, 220, 1374; Greaves, J. S., et al

  5. Hydrogen rotation-vibration oscillator

    DOEpatents

    Rhodes, C.K.

    1974-01-29

    A laser system is described wherein molecular species of hydrogen and hydrogen isotopes are induced to oscillate on rotational-vibrational levels by subjecting the hydrogen to a transverse beam of electrons of a narrowly defined energy between about 1 and 5 eV, thereby producing high intensity and high energy output. (Official Gazette)

  6. Liquid-Hydrogen Polygeneration System

    NASA Technical Reports Server (NTRS)

    Minderman, P.; Gutkowski, G.; Manfredi, L.; King, J.; Howard, F.

    1986-01-01

    Polygeneration system uses existing technology in integrated process to produce liquid hydrogen space-vehicle propellant and secondary products as gaseous nitrogen, electrical energy, and thermal energy. Makes commercial launch services economical. Lowers expected cost of liquid hydrogen by utilizing relatively cheap coal feedstocks and by reducing electrical costs associated with producing liquid hydrogen.

  7. Hydrogen and advanced aerospace materials

    NASA Technical Reports Server (NTRS)

    Nelson, Howard G.

    1988-01-01

    The hydrogen embrittlement is briefly reviewed and discussed in terms of specific structural materials considered for use on a generic, hydrogen-fueled, hypersonic aerospace vehicle. A few unusual hydrogen-material incompatibility concerns are identified and some solution methodologies are discussed that could potentially lessen these concerns.

  8. Nickel-hydrogen component development

    NASA Technical Reports Server (NTRS)

    Charleston, J. A.

    1983-01-01

    Light weight energy storage systems for future space missions are investigated. One of the systems being studied is the nickel hydrogen battery. This battery is designed to achieve longer life, improve performance, and higher energy densities for space applications. The nickel hydrogen component development is discussed. Test data from polarization measurements of the hydrogen electrode component is presented.

  9. Hydrogen, socio-environmental impact

    NASA Technical Reports Server (NTRS)

    Gilmore, J. S.; Matthews, W. E.; Duff, M. K.

    1975-01-01

    The concept and logic flow of a hydrogen technology assessment are described along with a specific procedure for such an assessment. The development of hydrogen technology is discussed. Factors considered in the development and use of hydrogen include: stimulus of societal needs and technological innovations; economic factors; and social and environmental effects.

  10. Hydrogen as an energy vector

    NASA Technical Reports Server (NTRS)

    Powers, W. D.

    1975-01-01

    The feasibility of utilizing hydrogen as an energy vector is considered, with special attention given to means of hydrogen production. The state-of-the-art in thermochemical processes is reviewed, and criteria for the technical and economic feasibility of large-scale thermochemical water splitting processes are presented. The production of hydrogen from coal and from photolysis of water is discussed.

  11. Hydrogen and sulfur recovery from hydrogen sulfide wastes

    DOEpatents

    Harkness, John B. L.; Gorski, Anthony J.; Daniels, Edward J.

    1993-01-01

    A process for generating hydrogen and elemental sulfur from hydrogen sulfide waste in which the hydrogen sulfide is associated under plasma conditions and a portion of the hydrogen output is used in a catalytic reduction unit to convert sulfur-containing impurities to hydrogen sulfide for recycle, the process also including the addition of an ionizing gas such as argon to initiate the plasma reaction at lower energy, a preheater for the input to the reactor and an internal adjustable choke in the reactor for enhanced coupling with the microwave energy input.

  12. Hydrogen and sulfur recovery from hydrogen sulfide wastes

    DOEpatents

    Harkness, J.B.L.; Gorski, A.J.; Daniels, E.J.

    1993-05-18

    A process is described for generating hydrogen and elemental sulfur from hydrogen sulfide waste in which the hydrogen sulfide is [dis]associated under plasma conditions and a portion of the hydrogen output is used in a catalytic reduction unit to convert sulfur-containing impurities to hydrogen sulfide for recycle, the process also including the addition of an ionizing gas such as argon to initiate the plasma reaction at lower energy, a preheater for the input to the reactor and an internal adjustable choke in the reactor for enhanced coupling with the microwave energy input.

  13. 1-D Radiative-Convective Model for Terrestrial Exoplanet Atmospheres

    NASA Astrophysics Data System (ADS)

    Leung, Cecilia W. S.; Robinson, Tyler D.

    2016-10-01

    We present a one dimensional radiative-convective model to study the thermal structure of terrestrial exoplanetary atmospheres. The radiative transfer and equilibrium chemistry in our model is based on similar methodologies in models used for studying Extrasolar Giant Planets (Fortney et al. 2005b.) We validated our model in the optically thin and thick limits, and compared our pressure-temperature profiles against the analytical solutions of Robinson & Catling (2012). For extrasolar terrestrial planets with pure hydrogen atmospheres, we evaluated the effects of H2-H2 collision induced absorption and identified the purely roto-translational band in our modeled spectra. We also examined how enhanced atmospheric metallicities affect the temperature structure, chemistry, and spectra of terrestrial exoplanets. For a terrestrial extrasolar planet whose atmospheric compostion is 100 times solar orbiting a sun-like star at 2 AU, our model resulted in a reducing atmosphere with H2O, CH4, and NH3 as the dominant greenhouse gases.

  14. Detection of an oxygen atmosphere on Jupiter's moon Europa.

    PubMed

    Hall, D T; Strobel, D F; Feldman, P D; McGrath, M A; Weaver, H A

    1995-02-23

    Europa, the second large satellite out from Jupiter, is roughly the size of Earth's Moon, but unlike the Moon, it has water ice on its surface. There have been suggestions that an oxygen atmosphere should accumulate around such a body, through reactions which break up the water molecules and form molecular hydrogen and oxygen. The lighter H2 molecules would escape from Europa relatively easily, leaving behind an atmosphere rich in oxygen. Here we report the detection of atomic oxygen emission from Europa, which we interpret as being produced by the simultaneous dissociation and excitation of atmospheric O2 by electrons from Jupiter's magnetosphere. Europa's molecular oxygen atmosphere is very tenuous, with a surface pressure about 10(-11) that of the Earth's atmosphere at sea level.

  15. Mars Atmospheric Capture and Gas Separation

    NASA Technical Reports Server (NTRS)

    Muscatello, Anthony; Santiago-Maldonado, Edgardo; Gibson, Tracy; Devor, Robert; Captain, James

    2011-01-01

    The Mars atmospheric capture and gas separation project is selecting, developing, and demonstrating techniques to capture and purify Martian atmospheric gases for their utilization for the production of hydrocarbons, oxygen, and water in ISRU systems. Trace gases will be required to be separated from Martian atmospheric gases to provide pure C02 to processing elements. In addition, other Martian gases, such as nitrogen and argon, occur in concentrations high enough to be useful as buffer gas and should be captured as welL To achieve these goals, highly efficient gas separation processes will be required. These gas separation techniques are also required across various areas within the ISRU project to support various consumable production processes. The development of innovative gas separation techniques will evaluate the current state-of-the-art for the gas separation required, with the objective to demonstrate and develop light-weight, low-power methods for gas separation. Gas separation requirements include, but are not limited to the selective separation of: (1) methane and water from un-reacted carbon oxides (C02- CO) and hydrogen typical of a Sabatier-type process, (2) carbon oxides and water from unreacted hydrogen from a Reverse Water-Gas Shift process, (3) carbon oxides from oxygen from a trash/waste processing reaction, and (4) helium from hydrogen or oxygen from a propellant scavenging process. Potential technologies for the separations include freezers, selective membranes, selective solvents, polymeric sorbents, zeolites, and new technologies. This paper and presentation will summarize the results of an extensive literature review and laboratory evaluations of candidate technologies for the capture and separation of C02 and other relevant gases.

  16. Study on Al2O3 extraction from activated coal gangue under different calcination atmospheres

    NASA Astrophysics Data System (ADS)

    Dong, Ling; Liang, Xinxing; Song, Qiang; Gao, Gewu; Song, Lihua; Shu, Yuanfeng; Shu, Xinqian

    2017-12-01

    Coal gangue was calcinated under air, nitrogen, carbon dioxide, air-hydrogen, and hydrogen atmospheres. The effects of different calcination temperatures and atmospheres on the mineral composition of activated coal gangue were investigated by X-ray diffraction. Moreover, the acid leaching kinetics of aluminum oxide from coal gangue was investigated with sulfuric acid. It showed that the air atmosphere promoted kaolinite decomposition during coal gangue calcination. The hydrogen atmosphere promoted the activation and decomposition of kaolinite at reaction temperatures exceeding 650°C. The carbon dioxide atmosphere eliminated the influence of residual carbon on coal gangue. When the ratio of acid/coal gangue was 1.5 and reaction temperature was 650°C, the sulfuric acid leaching rate under air, air-hydrogen, carbon dioxide, hydrogen and nitrogen atmospheres were 93.66%, 90.90%, 84.06%, 81.91% and 77.54% respectively. The acid leaching reaction process conformed to unreacted shrinking core model of particle unchanged, and was controlled by the interfacial chemical reaction. The reaction kinetic equation for the leaching process was 1-(1-x)1/3=kt with an apparent activation energy of 48.97 kJ/mol.

  17. Nightglow in the upper atmosphere of Mars and implications for atmospheric transport.

    PubMed

    Bertaux, Jean-Loup; Leblanc, François; Perrier, Séverine; Quemerais, E; Korablev, Oleg; Dimarellis, E; Reberac, A; Forget, F; Simon, P C; Stern, S A; Sandel, Bill

    2005-01-28

    We detected light emissions in the nightside martian atmosphere with the SPICAM (spectroscopy for the investigation of the characteristics of the atmosphere of Mars) ultraviolet (UV) spectrometer on board the Mars Express. The UV spectrum of this nightglow is composed of hydrogen Lyman alpha emission (121.6 nanometers) and the gamma and delta bands of nitric oxide (NO) (190 to 270 nanometers) produced when N and O atoms combine to produce the NO molecule. N and O atoms are produced by extreme UV photodissociation of O2, CO2, and N2 in the dayside upper atmosphere and transported to the night side. The NO emission is brightest in the winter south polar night because of continuous downward transport of air in this region at night during winter and because of freezing at ground level.

  18. Moisture-Induced Alumina Scale Spallation: The Hydrogen Factor

    NASA Technical Reports Server (NTRS)

    Smialek, James L.

    2009-01-01

    For some time our community has been concerned with interfacial spallation of protective alumina scales, not just upon immediate cooldown, but as a time-delayed phenomenon. Moisture-induced delayed spallation (MIDS) and desktop spallation (DTS) of TBC's refer to this process. It is most apparent for relatively adherent alumina scales that have survived cool down in a dry environment, built up considerable thickness and strain energy, and have been somewhat damaged, such as by cyclic oxidation cracking. Indeed, a "sweet zone" can be defined that maximizes the observed effect as a function of all the relevant factors. Moisture has been postulated to serve as a source of interfacial hydrogen embrittlement derived from reaction with aluminum in the alloy at an exposed interface. The purpose of this monograph is to trace the close analogy of this phenomenon to other hydrogen effects, such as embrittlement of aluminides and blistering of alloys and anodic alumina films. A formalized, top-down, logic tree structure is presented as a guide to this discussion. A theoretical basis for interfacial weakening by hydrogen is first cited, as are demonstrations of hydrogen as a reaction product or detected interfacial species. Further support is provided by critical experiments that produce the same moisture effect, but by isolating hydrogen from other potential causative factors. These experiments include tests in H2-containing atmospheres or cathodic hydrogen charging.

  19. Hot Hydrogen Testing of Refractory Metals and Ceramics

    NASA Technical Reports Server (NTRS)

    Zee, Ralph; Chin, Bryan; Cohron, Jon

    1993-01-01

    The objective of this investigation is to develop a technique with which refractory metal carbide samples can be exposed to hydrogen containing gases at high temperatures, and to use various microstructural and analytical techniques to determine the chemical and rate processes involved in hydrogen degradation in these materials. Five types of carbides were examined including WC, NbC, HfC, ZrC, and TaC. The ceramics were purchased and were all monolithic in nature. The temperature range investigated was from 850 to 1600 C with a hydrogen pressure of one atmosphere. Control experiments, in vacuum, were also conducted for comparison so that the net effects due to hydrogen could be isolated. The samples were analyzed prior to and after exposure. Gas samples were collected in selected experiments and analyzed using gas chromography. Characterization of the resulting microstructure after exposure to hydrogen was conducted using optical microscopy, x-ray diffraction, scanning electron microscopy, and weight change. The ceramics were purchased and were all monolithic in nature. It was found that all samples lost weight after exposure, both in hydrogen and vacuum. Results from the microstructure analyses show that the degradation processes are different among the five types of ceramics involved. In addition, the apparent activation energy for the degradation process is a function of temperature even within the same material. This indicates that there are more than one mechanism involved in each material, and that the mechanisms are temperature dependent.

  20. Electrochemical Hydrogen Peroxide Generator

    NASA Technical Reports Server (NTRS)

    Tennakoon, Charles L. K.; Singh, Waheguru; Anderson, Kelvin C.

    2010-01-01

    Two-electron reduction of oxygen to produce hydrogen peroxide is a much researched topic. Most of the work has been done in the production of hydrogen peroxide in basic media, in order to address the needs of the pulp and paper industry. However, peroxides under alkaline conditions show poor stabilities and are not useful in disinfection applications. There is a need to design electrocatalysts that are stable and provide good current and energy efficiencies to produce hydrogen peroxide under acidic conditions. The innovation focuses on the in situ generation of hydrogen peroxide using an electrochemical cell having a gas diffusion electrode as the cathode (electrode connected to the negative pole of the power supply) and a platinized titanium anode. The cathode and anode compartments are separated by a readily available cation-exchange membrane (Nafion 117). The anode compartment is fed with deionized water. Generation of oxygen is the anode reaction. Protons from the anode compartment are transferred across the cation-exchange membrane to the cathode compartment by electrostatic attraction towards the negatively charged electrode. The cathode compartment is fed with oxygen. Here, hydrogen peroxide is generated by the reduction of oxygen. Water may also be generated in the cathode. A small amount of water is also transported across the membrane along with hydrated protons transported across the membrane. Generally, each proton is hydrated with 3-5 molecules. The process is unique because hydrogen peroxide is formed as a high-purity aqueous solution. Since there are no hazardous chemicals or liquids used in the process, the disinfection product can be applied directly to water, before entering a water filtration unit to disinfect the incoming water and to prevent the build up of heterotrophic bacteria, for example, in carbon based filters. The competitive advantages of this process are: 1. No consumable chemicals are needed in the process. The only raw materials

  1. Secondary Atmospheres on HD 219134 b and c

    NASA Astrophysics Data System (ADS)

    Dorn, Caroline; Heng, Kevin

    2018-01-01

    We analyze the interiors of HD 219134 b and c, which are among the coolest super-Earths detected thus far. Without using spectroscopic measurements, we aim at constraining if the possible atmospheres are hydrogen-rich or hydrogen-poor. In the first step, we employ a full probabilistic Bayesian inference analysis to rigorously quantify the degeneracy of interior parameters given the data of mass, radius, refractory element abundances, semimajor axes, and stellar irradiation. We obtain constraints on structure and composition for core, mantle, ice layer, and atmosphere. In the second step, we aim to draw conclusions on the nature of possible atmospheres by considering atmospheric escape. Specifically, we compare the actual possible atmospheres to a threshold thickness above which a primordial (H2-dominated) atmosphere can be retained against evaporation over the planet’s lifetime. The best-constrained parameters are the individual layer thicknesses. The maximum radius fraction of possible atmospheres are 0.18 and 0.13 R (radius), for planets b and c, respectively. These values are significantly smaller than the threshold thicknesses of primordial atmospheres: 0.28 and 0.19 R, respectively. Thus, the possible atmospheres of planets b and c are unlikely to be H2-dominated. However, whether possible volatile layers are made of gas or liquid/solid water cannot be uniquely determined. Our main conclusions are (1) the possible atmospheres for planets b and c are enriched and thus possibly secondary in nature, and (2) both planets may contain a gas layer, whereas the layer of HD 219134 b must be larger. HD 219134 c can be rocky.

  2. The molecular dynamics of atmospheric reaction

    NASA Technical Reports Server (NTRS)

    Polanyi, J. C.

    1971-01-01

    Detailed information about the chemistry of the upper atmosphere took the form of quantitative data concerning the rate of reaction into specified states of product vibration, rotation and translation for exothermic reaction, as well as concerning the rate of reaction from specified states of reagent vibration, rotation and translation for endothermic reaction. The techniques used were variants on the infrared chemiluminescence method. Emphasis was placed on reactions that formed, and that removed, vibrationally-excited hydroxyl radicals. Fundamental studies were also performed on exothermic reactions involving hydrogen halides.

  3. Transport properties in the Jovian atmosphere

    NASA Technical Reports Server (NTRS)

    Biolsi, L.

    1978-01-01

    Transport properties in a Jupiter-like atmosphere (89 mol % hydrogen and 11 mol % helium) are obtained by using the method of the kinetic theory of gases. The transport collision integrals are calculated by fitting various two-body semiempirical interaction potentials for which the collision integrals are tabulated to ab initio quantum mechanical calculations of the two-body interactions. The collision integrals are used to calculate the binary diffusion coefficients, viscosity, and 'total' thermal conductivity of the pure gases and the gas mixtures at 1-atm pressure from 1000 K to 25,000 K.

  4. Scaled Testing of Hydrogen Gas Getters for Transuranic Waste

    SciTech Connect

    Kaszuba, J.; Mroz, E.; Haga, M.

    2006-07-01

    in the inner containment vessel of a TRUPACT-II container and volume of a payload of seven 55-gallon drums. The tests were conducted in an atmosphere of air for 60 days at ambient temperature (15 to 27 deg. C) and a scaled hydrogen generation rate of 2.60 E-07 moles hydrogen per second (0.35 cc/min). Hydrogen was successfully 'gettered' by both systems. Hydrogen concentrations remained below 5 vol% (in air) for the duration of the tests. However, catalytic reaction of hydrogen with carbon triple or double bonds in the getter materials did not take place. Instead, catalytic recombination was the predominant mechanism in both getters as evidenced by 1) consumption of oxygen in the bell-jars; 2) production of free water in the bell-jars; and 3) absence of chemical changes in both getters as shown by NMR spectra. (authors)« less

  5. Ultra-high sensitive optical fiber hydrogen sensor using self-referenced demodulation method and WO3-Pd2Pt-Pt composite film.

    PubMed

    Dai, Jixiang; Peng, Wen; Wang, Gaopeng; Xiang, Feng; Qin, Yuhuan; Wang, Min; Dai, Yutang; Yang, Minghong; Deng, Hui; Zhang, Pengcheng

    2017-02-06

    A novel fiber optic hydrogen concentration detection platform with significantly enhanced performance is proposed and demonstrated in this paper. The hydrogen sensing probe was prepared by depositing WO3-Pd2Pt-Pt composite film on the fiber tip of two Bragg gratings paired with high-low reflectivity. At a room temperature of 25°C, the hydrogen sensor has a significant response towards 10 ppm hydrogen in nitrogen atmosphere, and may detect tens of ppb hydrogen changes when the hydrogen concentration is between 10~60 ppm. Besides, the proposed system shows quick response when the hydrogen concentration is above 40 ppm. Moreover, the hydrogen sensor shows good repeatability during the hydrogen response. This work proposes a new concept to develop hydrogen sensing technology with ultra-high sensitivity, which can significantly promote its potential application in various fields, especially for ultra-low hydrogen detection in oxygen-free environment.

  6. Hydrogen diffusion in Zircon

    NASA Astrophysics Data System (ADS)

    Ingrin, Jannick; Zhang, Peipei

    2016-04-01

    Hydrogen mobility in gem quality zircon single crystals from Madagascar was investigated through H-D exchange experiments. Thin slices were annealed in a horizontal furnace flushed with a gas mixture of Ar/D2(10%) under ambient pressure between 900 ° C to 1150 ° C. FTIR analyses were performed on oriented slices before and after each annealing run. H diffusion along [100] and [010] follow the same diffusion law D = D0exp[-E /RT], with log D0 = 2.24 ± 1.57 (in m2/s) and E = 374 ± 39 kJ/mol. H diffusion along [001] follows a slightly more rapid diffusion law, with log D0 = 1.11 ± 0.22 (in m2/s) and E = 334 ± 49 kJ/mol. H diffusion in zircon has much higher activation energy and slower diffusivity than other NAMs below 1150 ° C even iron-poor garnets which are known to be among the slowest (Blanchard and Ingrin, 2004; Kurka et al. 2005). During H-D exchange zircon incorporates also deuterium. This hydration reaction involves uranium reduction as it is shown from the exchange of U5+ and U4+ characteristic bands in the near infrared region during annealing. It is the first time that a hydration reaction U5+ + OH- = U4+ + O2- + 1/2H2, is experimentally reported. The kinetics of deuterium incorporation is slightly slower than hydrogen diffusion, suggesting that the reaction is limited by hydrogen mobility. Hydrogen isotopic memory of zircon is higher than other NAMs. Zircons will be moderately retentive of H signatures at mid-crustal metamorphic temperatures. At 500 ° C, a zircon with a radius of 300 μm would retain its H isotopic signature over more than a million years. However, a zircon is unable to retain this information for geologically significant times under high-grade metamorphism unless the grain size is large enough. Refrences Blanchard, M. and Ingrin, J. (2004) Hydrogen diffusion in Dora Maira pyrope. Physics and Chemistry of Minerals, 31, 593-605. Kurka, A., Blanchard, M. and Ingrin, J. (2005) Kinetics of hydrogen extraction and deuteration in

  7. Solid evacuated microspheres of hydrogen

    DOEpatents

    Turnbull, Robert J.; Foster, Christopher A.; Hendricks, Charles D.

    1982-01-01

    A method is provided for producing solid, evacuated microspheres comprised of hydrogen. The spheres are produced by forming a jet of liquid hydrogen and exciting mechanical waves on the jet of appropriate frequency so that the jet breaks up into drops with a bubble formed in each drop by cavitation. The drops are exposed to a pressure less than the vapor pressure of the liquid hydrogen so that the bubble which is formed within each drop expands. The drops which contain bubbles are exposed to an environment having a pressure just below the triple point of liquid hydrogen and they thereby freeze giving solid, evacuated spheres of hydrogen.

  8. Hydrogen storage and evolution catalysed by metal hydride complexes.

    PubMed

    Fukuzumi, Shunichi; Suenobu, Tomoyoshi

    2013-01-07

    The storage and evolution of hydrogen are catalysed by appropriate metal hydride complexes. Hydrogenation of carbon dioxide by hydrogen is catalysed by a [C,N] cyclometalated organoiridium complex, [Ir(III)(Cp*)(4-(1H-pyrazol-1-yl-κN(2))benzoic acid-κC(3))(OH(2))](2)SO(4) [Ir-OH(2)](2)SO(4), under atmospheric pressure of H(2) and CO(2) in weakly basic water (pH 7.5) at room temperature. The reverse reaction, i.e., hydrogen evolution from formate, is also catalysed by [Ir-OH(2)](+) in acidic water (pH 2.8) at room temperature. Thus, interconversion between hydrogen and formic acid in water at ambient temperature and pressure has been achieved by using [Ir-OH(2)](+) as an efficient catalyst in both directions depending on pH. The Ir complex [Ir-OH(2)](+) also catalyses regioselective hydrogenation of the oxidised form of β-nicotinamide adenine dinucleotide (NAD(+)) to produce the 1,4-reduced form (NADH) under atmospheric pressure of H(2) at room temperature in weakly basic water. In weakly acidic water, the complex [Ir-OH(2)](+) also catalyses the reverse reaction, i.e., hydrogen evolution from NADH to produce NAD(+) at room temperature. Thus, interconversion between NADH (and H(+)) and NAD(+) (and H(2)) has also been achieved by using [Ir-OH(2)](+) as an efficient catalyst and by changing pH. The iridium hydride complex formed by the reduction of [Ir-OH(2)](+) by H(2) and NADH is responsible for the hydrogen evolution. Photoirradiation (λ > 330 nm) of an aqueous solution of the Ir-hydride complex produced by the reduction of [Ir-OH(2)](+) with alcohols resulted in the quantitative conversion to a unique [C,C] cyclometalated Ir-hydride complex, which can catalyse hydrogen evolution from alcohols in a basic aqueous solution (pH 11.9). The catalytic mechanisms of the hydrogen storage and evolution are discussed by focusing on the reactivity of Ir-hydride complexes.

  9. Hydrogen/deuterium exchange in mass spectrometry.

    PubMed

    Kostyukevich, Yury; Acter, Thamina; Zherebker, Alexander; Ahmed, Arif; Kim, Sunghwan; Nikolaev, Eugene

    2018-03-30

    The isotopic exchange approach is in use since the first observation of such reactions in 1933 by Lewis. This approach allows the investigation of the pathways of chemical and biochemical reactions, determination of structure, composition, and conformation of molecules. Mass spectrometry has now become one of the most important analytical tools for the monitoring of the isotopic exchange reactions. Investigation of conformational dynamics of proteins, quantitative measurements, obtaining chemical, and structural information about individual compounds of the complex natural mixtures are mainly based on the use of isotope exchange in combination with high resolution mass spectrometry. The most important reaction is the Hydrogen/Deuterium exchange, which is mainly performed in the solution. Recently we have developed the approach allowing performing of the Hydrogen/Deuterium reaction on-line directly in the ionization source under atmospheric pressure. Such approach simplifies the sample preparation and can accelerate the exchange reaction so that certain hydrogens that are considered as non-labile will also participate in the exchange. The use of in-ionization source H/D exchange in modern mass spectrometry for structural elucidation of molecules serves as the basic theme in this review. We will focus on the mechanisms of the isotopic exchange reactions and on the application of in-ESI, in-APCI, and in-APPI source Hydrogen/Deuterium exchange for the investigation of petroleum, natural organic matter, oligosaccharides, and proteins including protein-protein complexes. The simple scenario for adaptation of H/D exchange reactions into mass spectrometric method is also highlighted along with a couple of examples collected from previous studies. © 2018 Wiley Periodicals, Inc.

  10. Multiscale modelling of the interaction of hydrogen with interstitial defects and dislocations in BCC tungsten

    NASA Astrophysics Data System (ADS)

    De Backer, A.; Mason, D. R.; Domain, C.; Nguyen-Manh, D.; Marinica, M.-C.; Ventelon, L.; Becquart, C. S.; Dudarev, S. L.

    2018-01-01

    In a fusion tokamak, the plasma of hydrogen isotopes is in contact with tungsten at the surface of a divertor. In the bulk of the material, the hydrogen concentration profile tends towards dynamic equilibrium between the flux of incident ions and their trapping and release from defects, either native or produced by ion and neutron irradiation. The dynamics of hydrogen exchange between the plasma and the material is controlled by pressure, temperature, and also by the energy barriers characterizing hydrogen diffusion in the material, trapping and de-trapping from defects. In this work, we extend the treatment of interaction of hydrogen with vacancy-type defects, and investigate how hydrogen is trapped by self-interstitial atom defects and dislocations. The accumulation of hydrogen on dislocation loops and dislocations is assessed using a combination of density functional theory (DFT), molecular dynamics with empirical potentials, and linear elasticity theory. The equilibrium configurations adopted by hydrogen atoms in the core of dislocations as well as in the elastic fields of defects, are modelled by DFT. The structure of the resulting configurations can be rationalised assuming that hydrogen atoms interact elastically with lattice distortions and that they interact between themselves through short-range repulsion. We formulate a two-shell model for hydrogen interaction with an interstitial defect of any size, which predicts how hydrogen accumulates at defects, dislocation loops and line dislocations at a finite temperature. We derive analytical formulae for the number of hydrogen atoms forming the Cottrell atmosphere of a mesoscopic dislocation loop or an edge dislocation. The solubility of hydrogen as a function of temperature, pressure and the density of dislocations exhibits three physically distinct regimes, dominated by the solubility of hydrogen in a perfect lattice, its retention at dislocation cores, and trapping by long-range elastic fields of

  11. Atmospheric Habitable Zones in Y Dwarf Atmospheres

    SciTech Connect

    Yates, Jack S.; Palmer, Paul I.; Biller, Beth

    2017-02-20

    We use a simple organism lifecycle model to explore the viability of an atmospheric habitable zone (AHZ), with temperatures that could support Earth-centric life, which sits above an environment that does not support life. To illustrate our model, we use a cool Y dwarf atmosphere, such as WISE J085510.83–0714442.5, whose 4.5–5.2 μ m spectrum shows absorption features consistent with water vapor and clouds. We allow organisms to adapt to their atmospheric environment (described by temperature, convection, and gravity) by adopting different growth strategies that maximize their chance of survival and proliferation. We assume a constant upward vertical velocity through themore » AHZ. We found that the organism growth strategy is most sensitive to the magnitude of the atmospheric convection. Stronger convection supports the evolution of more massive organisms. For a purely radiative environment, we find that evolved organisms have a mass that is an order of magnitude smaller than terrestrial microbes, thereby defining a dynamical constraint on the dimensions of life that an AHZ can support. Based on a previously defined statistical approach, we infer that there are of the order of 10{sup 9} cool Y brown dwarfs in the Milky Way, and likely a few tens of these objects are within 10 pc from Earth. Our work also has implications for exploring life in the atmospheres of temperate gas giants. Consideration of the habitable volumes in planetary atmospheres significantly increases the volume of habitable space in the galaxy.« less

  12. Phytoremediation of Atmospheric Methane

    DTIC Science & Technology

    2013-04-15

    REPORT Phytoremediation of Atmospheric Methane 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: We have transformed a plant, Arabidopsis thaliana, with the...298 (Rev 8/98) Prescribed by ANSI Std. Z39.18 - 31-Mar-2012 Phytoremediation of Atmospheric Methane Report Title ABSTRACT We have transformed a...DD882) Scientific Progress See attachment Technology Transfer 1    Final Report for DARPA project W911NF1010027  Phytoremediation  of Atmospheric

  13. Sources of atmospheric ammonia

    NASA Technical Reports Server (NTRS)

    Harriss, R. C.; Michaels, J. T.

    1982-01-01

    The information available on factors that influence emissions from the principal societal sources of ammonia to the atmosphere, namely combustion processes, volatilization of farm animal wastes, and volatilization of fertilizers, is reviewed. Emission factors are established for each major source of atmospheric ammonia. The factors are then multiplied by appropriate source characterization descriptors to obtain calculated fluxes of ammonia to the atmosphere on a state-by-state basis for the United States.

  14. Oscillations in stellar atmospheres

    NASA Technical Reports Server (NTRS)

    Costa, A.; Ringuelet, A. E.; Fontenla, J. M.

    1989-01-01

    Atmospheric excitation and propagation of oscillations are analyzed for typical pulsating stars. The linear, plane-parallel approach for the pulsating atmosphere gives a local description of the phenomenon. From the local analysis of oscillations, the minimum frequencies are obtained for radially propagating waves. The comparison of the minimum frequencies obtained for a variety of stellar types is in good agreement with the observed periods of the oscillations. The role of the atmosphere in the globar stellar pulsations is thus emphasized.

  15. Global Atmospheric Aerosol Modeling

    NASA Technical Reports Server (NTRS)

    Hendricks, Johannes; Aquila, Valentina; Righi, Mattia

    2012-01-01

    Global aerosol models are used to study the distribution and properties of atmospheric aerosol particles as well as their effects on clouds, atmospheric chemistry, radiation, and climate. The present article provides an overview of the basic concepts of global atmospheric aerosol modeling and shows some examples from a global aerosol simulation. Particular emphasis is placed on the simulation of aerosol particles and their effects within global climate models.

  16. Atmospheric density models

    NASA Technical Reports Server (NTRS)

    Mueller, A. C.

    1977-01-01

    An atmospheric model developed by Jacchia, quite accurate but requiring a large amount of computer storage and execution time, was found to be ill-suited for the space shuttle onboard program. The development of a simple atmospheric density model to simulate the Jacchia model was studied. Required characteristics including variation with solar activity, diurnal variation, variation with geomagnetic activity, semiannual variation, and variation with height were met by the new atmospheric density model.

  17. Atmospheres from Within

    NASA Technical Reports Server (NTRS)

    Morgan, Thomas; Abshire, James; Clancy, Todd; Fry, Ghee; Gustafson, Bo; Hecht, Michael; Kostiuk, Theodor; Rall, Jonathan; Reuter, Dennis; Sheldon, Robert

    1996-01-01

    In this review of atmospheric investigations from planetary surfaces, a wide variety of measurement and instrument techniques relevant to atmospheric studies from future planetary lander missions are discussed. The diversity of planetary surface environments within the solar system precludes complete or highly specific coverage, but lander investigations for Mars and cometary missions are presented as specific cases that represent the broad range of atmospheric-surface boundaries and that also correspond to high priority goals for future national and international lander missions.

  18. Hydrogen effects in metal catalysts

    SciTech Connect

    Paal, Z.; Menon, P.G.

    1983-01-01

    Only a small portion of hydrogen-metal interactions are covered in this review. The emphasis is on peculiar changes in chemisorptive and catalytic properties of metal catalysts brought about by their exposure to hydrogen above 670 to 770/sup 0/K. Electron loss spectroscopy or work function measurements can be used for the investigation of hydrogen on metals. Most useful are techniques where the effects of hydrogen manifest themselves indirectly, as in temperature-programmed desorption, radiotracer studies, electron microscopy, or x-ray diffraction along with chemisorption and hydrogen/oxygen titation. Combined techniques, NMR, magnetic measurements, electrochemistry, are also available. A review of these aspects is presented.more » The next section summarizes hydrogen effects on catalytic activity and selectivity in hydrogenation/dehydrogenation, skeletal rearrangments. A brief survey of technological implications is included. 203 references, 29 figures, 22 tables.« less

  19. The role of surface oxides on hydrogen sorption kinetics in titanium thin films

    NASA Astrophysics Data System (ADS)

    Hadjixenophontos, Efi; Michalek, Lukas; Roussel, Manuel; Hirscher, Michael; Schmitz, Guido

    2018-05-01

    Titanium is presently discussed as a catalyst to accelerate the hydrogenation kinetics of hydrogen storage materials. It is however known that H absorption in Ti decisively depends on the surface conditions (presence or absence of the natural surface oxide). In this work, we use Ti thin films of controlled thickness (50-800 nm) as a convenient tool for quantifying the atomic transport. XRD and TEM investigations allow us to follow the hydrogenation progress inside the film. Hydrogenation of TiO2/Ti bi-layers is studied at 300 °C, for different durations (10 s to 600 min) and at varying pressures of pure H2 atmosphere. Under these conditions, the hydrogenation is found to be linear in time. By comparing films with and without TiO2, as well as by studying the pressure dependence of hydrogenation, it is demonstrated that hydrogen transport across the oxide represents the decisive kinetic barrier rather than the splitting of H2 molecules at the surface. Hydrogenation appears by a layer-like reaction initiated by heterogeneous nucleation at the backside interface to the substrate. The linear growth constant and the H diffusion coefficient inside the oxide are quantified, as well as a reliable lower bound to the hydrogen diffusion coefficient in Ti is derived. The pressure dependence of hydrogen absorption is quantitatively modelled.

  20. Microwave Plasma Hydrogen Recovery System

    NASA Technical Reports Server (NTRS)

    Atwater, James; Wheeler, Richard, Jr.; Dahl, Roger; Hadley, Neal

    2010-01-01

    A microwave plasma reactor was developed for the recovery of hydrogen contained within waste methane produced by Carbon Dioxide Reduction Assembly (CRA), which reclaims oxygen from CO2. Since half of the H2 reductant used by the CRA is lost as CH4, the ability to reclaim this valuable resource will simplify supply logistics for longterm manned missions. Microwave plasmas provide an extreme thermal environment within a very small and precisely controlled region of space, resulting in very high energy densities at low overall power, and thus can drive high-temperature reactions using equipment that is smaller, lighter, and less power-consuming than traditional fixed-bed and fluidized-bed catalytic reactors. The high energy density provides an economical means to conduct endothermic reactions that become thermodynamically favorable only at very high temperatures. Microwave plasma methods were developed for the effective recovery of H2 using two primary reaction schemes: (1) methane pyrolysis to H2 and solid-phase carbon, and (2) methane oligomerization to H2 and acetylene. While the carbon problem is substantially reduced using plasma methods, it is not completely eliminated. For this reason, advanced methods were developed to promote CH4 oligomerization, which recovers a maximum of 75 percent of the H2 content of methane in a single reactor pass, and virtually eliminates the carbon problem. These methods were embodied in a prototype H2 recovery system capable of sustained high-efficiency operation. NASA can incorporate the innovation into flight hardware systems for deployment in support of future long-duration exploration objectives such as a Space Station retrofit, Lunar outpost, Mars transit, or Mars base. The primary application will be for the recovery of hydrogen lost in the Sabatier process for CO2 reduction to produce water in Exploration Life Support systems. Secondarily, this process may also be used in conjunction with a Sabatier reactor employed to

  1. Reversible hydrogen storage materials

    DOEpatents

    Ritter, James A [Lexington, SC; Wang, Tao [Columbia, SC; Ebner, Armin D [Lexington, SC; Holland, Charles E [Cayce, SC

    2012-04-10

    In accordance with the present disclosure, a process for synthesis of a complex hydride material for hydrogen storage is provided. The process includes mixing a borohydride with at least one additive agent and at least one catalyst and heating the mixture at a temperature of less than about 600.degree. C. and a pressure of H.sub.2 gas to form a complex hydride material. The complex hydride material comprises MAl.sub.xB.sub.yH.sub.z, wherein M is an alkali metal or group IIA metal, Al is the element aluminum, x is any number from 0 to 1, B is the element boron, y is a number from 0 to 13, and z is a number from 4 to 57 with the additive agent and catalyst still being present. The complex hydride material is capable of cyclic dehydrogenation and rehydrogenation and has a hydrogen capacity of at least about 4 weight percent.

  2. Container for hydrogen isotopes

    DOEpatents

    Solomon, David E.

    1977-01-01

    A container for the storage, shipping and dispensing of hydrogen isotopes such as hydrogen, deuterium, tritium, or mixtures of the same which has compactness, which is safe against fracture or accident, and which is reusable. The container consists of an outer housing with suitable inlet and outlet openings and electrical feed elements, the housing containing an activated sorber material in the form, for example, of titanium sponge or an activated zirconium aluminate cartridge. The gas to be stored is introduced into the chamber under conditions of heat and vacuum and will be retained in the sorber material. Subsequently, it may be released by heating the unit to drive off the stored gas at desired rates.

  3. Biological hydrogen production

    SciTech Connect

    Benemann, J.R.

    1995-11-01

    Biological hydrogen production can be accomplished by either thermochemical (gasification) conversion of woody biomass and agricultural residues or by microbiological processes that yield hydrogen gas from organic wastes or water. Biomass gasification is a well established technology; however, the synthesis gas produced, a mixture of CO and H{sub 2}, requires a shift reaction to convert the CO to H{sub 2}. Microbiological processes can carry out this reaction more efficiently than conventional catalysts, and may be more appropriate for the relatively small-scale of biomass gasification processes. Development of a microbial shift reaction may be a near-term practical application of microbial hydrogenmore » production.« less

  4. Thermochemical production of hydrogen

    DOEpatents

    Dreyfuss, Robert M.

    1976-07-13

    A thermochemical reaction cycle for the generation of hydrogen from water comprising the following sequence of reactions wherein M represents a metal and Z represents a metalloid selected from the arsenic-antimony-bismuth and selenium-tellurium subgroups of the periodic system: 2MO + Z + SO.sub.2 .fwdarw. MZ + MSO.sub.4 (1) mz + h.sub.2 so.sub.4 .fwdarw. mso.sub.4 + h.sub.2 z (2) 2mso.sub.4 .fwdarw. 2mo + so.sub.2 + so.sub.3 + 1/20.sub.2 (3) h.sub.2 z .fwdarw. z + h.sub.2 (4) h.sub.2 o + so.sub.3 .fwdarw. h.sub.2 so.sub.4 (5) the net reaction is the decomposition of water into hydrogen and oxygen.

  5. Hydrogen Reclamation and Reutilization

    NASA Technical Reports Server (NTRS)

    Hebert, Bartt; Lansaw, John

    2009-01-01

    John C. Stennis Space Center (SSC) provides rocket engine propulsion testing for NASA's space programs. Since the development of the Space Shuttle, every Space Shuttle Main Engine (SSME) has undergone acceptance testing at SSC before going to Kennedy Space Center (KSC) for integration into the Space Shuttle. The SSME is a large cryogenic rocket engine that uses Liquid Hydrogen (LH2) as the fuel. As NASA moves to the new ARES V launch system, the main engines on the new vehicle, as well as the upper stage engine, are currently base lined to be cryogenic rocket engines that will also use LH2. The main rocket engines for the ARES V will be larger than the SSME, while the upper stage engine will be approximately half that size. As a result, significant quantities of hydrogen will be required during the development, testing, and operation of these rocket engines.

  6. Atmospheric chemistry of peroxides: a review

    NASA Astrophysics Data System (ADS)

    Gunz, Dieter W.; Hoffmann, Michael R.

    Inorganic and organic peroxides have become the focus of increased attention by atmospheric chemists during the last decade. Hydrogen peroxide serves as an important link between gas phase radicals and aqueous phase chemistry in the atmosphere. As an important aqueous phase oxidant of S(IV), H 2O 2 plays a major role in the acidification of clouds, fogs, dew and rain. Several studies have indicated that peroxides and their precursor radicals cause damage to a variety of plant tissue. In this article we review analytical techniques, discuss and review the various sources of peroxides in the gas and aqueous phases and examine their reactions with S(IV) and N(III).

  7. Atmospheres of Exoplanets

    NASA Astrophysics Data System (ADS)

    Ehrenreich, David

    Atmospheres of exoplanets are our only window into the physical and chemical processes occurring in these distant worlds. These processes are important tracers of the origins and evolution of planetary systems, including our Solar System. In this broader context, we could better understand how common (or unique) are the conditions leading to the emergence of life, which could leave its spectroscopic imprints precisely into planetary atmospheres. This lecture is focused on one of the available techniques to study exoplanetary atmospheres: transit transmission spectroscopy. After describing some basics about this technique, I will illustrate through some case studies how it can practically bring observational constraints on these remote and exotic atmospheres.

  8. Understanding Callisto's Atmosphere

    NASA Astrophysics Data System (ADS)

    Spencer, John

    2016-10-01

    We plan to address first-order questions about the nature and origin of the mysterious atmosphere of Callisto, including its composition, longitudinal distribution, formation, and support mechanisms. This investigation is made possible by the remarkable sensitivity of the COS instrument, which has recently detected faint 1304 A and 1356 A O I emission from Callisto's leading / Jupiter-facing quadrant. The emission is probably due to dissociation of O2 molecules in Callisto's atmosphere by photo-electrons, and resonant scattering from an extended atomic O corona. We suspect, from Galileo ionospheric data, that the atmosphere may be much denser, and brighter in emission, on the trailing hemisphere, as expected for a sputter-generated atmosphere, and propose to test the sputter generation hypothesis with 4-orbit COS integrations on the leading and trailing hemispheres. If the trailing side emissions are indeed brighter, the improved SNR there will also allow much improved determination of atmospheric and coronal composition and optical depth. The observations will set the stage for, and aid in planning of, the extensive observations of Callisto's environment planned for the JUICE mission. Because Callisto's atmospheric oxygen emissions are indirectly illuminated by sunlight, which is uniform and quantifiable, it is much easier to understand atmospheric spatial distribution, and thus origin, than on Europa and Ganymede were emissions depend on magnetospheric excitation which is spatially variable and poorly understood. Callisto's atmosphere thus provides a unique chance to better understand the oxygen atmospheres of all the icy Galilean moons.

  9. Composition and evolution of the atmosphere of Venus

    NASA Technical Reports Server (NTRS)

    Donahue, Thomas (Principal Investigator)

    1996-01-01

    The contract year started by analyzing Jovian atmospheric data acquired by the Galileo Probe Mass Spectrometer (GPMS). Two Venus hydrogen projects got underway as well. The first study strives to understand how to reconcile the standard treatment of the evolution of the H2O and HDO resevoirs on Venus over 4.5 Gyr in the presence of H and D escape and injection by comets. The second study is calculating the charge exchange contribution to hydrogen loss rates, using realistic models for exospheric H, H(+), D, D(+), and ion temperature from PV data. This report includes the following papers as attachments and supporting data: 'The Galileo Probe Mass Spectrometer: Composition of Jupiter's Atmosphere'; 'Chemical Composition Measurements of the Atmosphere of Jupiter with the Galileo Probe Mass Spectrometer'; 'Ion/Neutral Escape of Hydrogen and Deuterium: Evolution of Water'; 'Hydrogen and Deuterium in the Thermosphere of Venus: Solar Cycle Variations and Escape'; and 'Solar Cycle Variations in H(+) and D(+) Densities in the Venus Ionosphere: Implications for Escape'.

  10. Coal liquefaction and hydrogenation

    DOEpatents

    Schindler, Harvey D.

    1985-01-01

    The coal liquefaction process disclosed uses three stages. The first stage is a liquefaction. The second and third stages are hydrogenation stages at different temperatures and in parallel or in series. One stage is within 650.degree.-795.degree. F. and optimizes solvent production. The other stage is within 800.degree.-840.degree. F. and optimizes the C.sub.5 -850.degree. F. product.

  11. Molecular and Metallic Hydrogen

    DTIC Science & Technology

    1977-05-01

    metallic hydrogen (-1400 sec) compared with that of a rocket fuel, such as JP4 plus liq- uid oxygen (-400 sec), makes it potentially attractive as a rocket... make it attractive for aircraft propulsion. However, if the transi- tion energy release rate is not controllable once the transihion is initiated...apprcximately 35 times more powerful than TNT (E - 1.354 kcal/g). Its high density should also make metallic hydro- gen useful in nuclear weapons

  12. Hydrogen Exchange Mass Spectrometry

    PubMed Central

    Mayne, Leland

    2018-01-01

    Hydrogen exchange (HX) methods can reveal much about the structure, energetics, and dynamics of proteins. The addition of mass spectrometry (MS) to an earlier fragmentation-separation HX analysis now extends HX studies to larger proteins at high structural resolution and can provide information not available before. This chapter discusses experimental aspects of HX labeling, especially with respect to the use of MS and the analysis of MS data. PMID:26791986

  13. Moisture-Induced Alumina Scale Spallation: The Hydrogen Factor

    NASA Technical Reports Server (NTRS)

    Smialek, James L.

    2010-01-01

    For some time the oxidation community has been concerned with interfacial spallation of protective alumina scales, not just upon immediate cool down, but as a time-delayed phenomenon. Moisture-induced delayed spallation (MIDS) and desktop spallation (DTS) of thermal barrier coatings (TBCs) refer to this process. It is most apparent for relatively adherent alumina scales that have survived initial cool down in a dry environment, have built up considerable thickness and strain energy, and have been somewhat damaged, such as by cyclic oxidation cracking. Indeed, a "sensitive zone" can be described that maximizes the observed effect as a function of all the relevant factors. Moisture has been postulated to serve as a source of interfacial hydrogen embrittlement. Hydrogen is derived from reaction with aluminum in the alloy at an exposed interface. The purpose of this monograph is to trace the close analogy of this phenomenon to other hydrogen-induced effects, such as embrittlement of aluminides and blistering of alloys and anodic alumina films. A formalized, top-down, logic-tree structure is presented as a guide to this discussion. A theoretical basis for interfacial weakening by hydrogen is first cited, as are demonstrations of hydrogen detection as a reaction product or interfacial species. Further support is provided by critical experiments that recreate the moisture effect, but by isolating hydrogen from other potential causative factors. These experiments include tests in H 2-containing atmospheres or cathodic hydrogen charging. Accordingly, they strongly indicate that interfacial hydrogen, derived from moisture, is the key chemical species accounting for delayed alumina scale spallation.

  14. Suicide with hydrogen sulfide.

    PubMed

    Sams, Ralph Newton; Carver, H Wayne; Catanese, Charles; Gilson, Thomas

    2013-06-01

    This presentation will address the recent rise of suicide deaths resulting from the asphyxiation by hydrogen sulfide (H2S) gas.Hydrogen sulfide poisoning has been an infrequently encountered cause of death in medical examiner practice. Most H2S deaths that have been reported occurred in association with industrial exposure.More recently, H2S has been seen in the commission of suicide, particularly in Japan. Scattered reports of this phenomenon have also appeared in the United States.We have recently observed 2 intentional asphyxial deaths in association with H2S. In both cases, the decedents committed suicide in their automobiles. They generated H2S by combining a sulfide-containing tree spray with toilet bowl cleaner (with an active ingredient of hydrogen chloride acid). Both death scenes prompted hazardous materials team responses because of notes attached to the victims' car windows indicating the presence of toxic gas. Autopsy findings included discoloration of lividity and an accentuation of the gray matter of the brain. Toxicology testing confirmed H2S exposure with the demonstration of high levels of thiosulfate in blood.In summary, suicide with H2S appears to be increasing in the United States.

  15. HELIUM ATMOSPHERES ON WARM NEPTUNE- AND SUB-NEPTUNE-SIZED EXOPLANETS AND APPLICATIONS TO GJ 436b

    SciTech Connect

    Hu, Renyu; Yung, Yuk L.; Seager, Sara, E-mail: renyu.hu@jpl.nasa.gov

    2015-07-01

    Warm Neptune- and sub-Neptune-sized exoplanets in orbits smaller than Mercury’s are thought to have experienced extensive atmospheric evolution. Here we propose that a potential outcome of this atmospheric evolution is the formation of helium-dominated atmospheres. The hydrodynamic escape rates of Neptune- and sub-Neptune-sized exoplanets are comparable to the diffusion-limited escape rate of hydrogen, and therefore the escape is heavily affected by diffusive separation between hydrogen and helium. A helium atmosphere can thus be formed—from a primordial hydrogen–helium atmosphere—via atmospheric hydrodynamic escape from the planet. The helium atmosphere has very different abundances of major carbon and oxygen species from those ofmore » a hydrogen atmosphere, leading to distinctive transmission and thermal emission spectral features. In particular, the hypothesis of a helium-dominated atmosphere can explain the thermal emission spectrum of GJ 436b, a warm Neptune-sized exoplanet, while also being consistent with the transmission spectrum. This model atmosphere contains trace amounts of hydrogen, carbon, and oxygen, with the predominance of CO over CH{sub 4} as the main form of carbon. With our atmospheric evolution model, we find that if the mass of the initial atmosphere envelope is 10{sup −3} planetary mass, hydrodynamic escape can reduce the hydrogen abundance in the atmosphere by several orders of magnitude in ∼10 billion years. Observations of exoplanet transits may thus detect signatures of helium atmospheres and probe the evolutionary history of small exoplanets.« less

  16. HITRAN2012 and Remote Sensing of Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Gordon, I. E.; Rothman, L. S.; Li, G.

    2013-06-01

    For the recently-released HITRAN2012 edition of the database, a substantial effort was taken to extend the HITRAN database to have capabilities for studying a variety of planetary atmospheres. Spectroscopic parameters for gases and spectral bands of molecules that are germane to the studies of planetary atmospheres have been assembled. These parameters include the types of data that have already been considered for transmission and radiance algorithms, such as line position, intensity, broadening coefficients, lower-state energies, and temperature dependence values. Besides adding new bands and isotopologues to the relevant molecules that already exist in HITRAN (methane, hydrogen halides, hydrogen disulfide, etc.), a number of new molecules, namely H_2, CS, C_4H_2, HC_3N and SO_3 have been incorporated into the HITRAN2012 database. For some of the molecules, additional parameters, beyond what is currently considered for the terrestrial atmosphere, have been archived. Examples are pressure-broadened half widths due to various foreign partners. Collision-induced absorption data for a large variety of the collision partners are provided in HITRAN for the first time. Future efforts, including preparation of a new edition of the HITEMP database, will be discussed. Note that another talk is given in the "Atmospheric Species" session, describing HITRAN improvements towards remote sensing of terrestrial atmosphere. This effort is supported by the NASA Planetary Atmospheres program, under the grant NNX10AB94G. L. S. Rothman, I. E. Gordon, et al. "The HITRAN 2012 molecular spectroscopic database," JQSRT, submitted 2013.

  17. Transmission Electron Microscopy and Electron Energy-Loss Spectroscopy Analysis of Hydrogenated Nanostructured Graphite Prepared by Mechanical Milling

    NASA Astrophysics Data System (ADS)

    Muto, Shunsuke; Kimura, Tomohiko; Tanabe, Tetsuo; Kiyobayashi, Tetsu; Maruyama, Tadashi

    2005-04-01

    Hydrogen trapping sites in hydrogenated nanostructured graphite (HNG) prepared by mechanical milling under hydrogen atmosphere were intensively studied with transmission electron microscopy (TEM) and electron energy-loss spectroscopy (EELS). Measurements of σ- and π-plasmon dispersion and 1s→ 2p* excitation spectra of the graphitic matrix suggested the existence of at least two types of hydrogen trapping states: one was the conventional C-H covalent bond, and the other was related to the π-orbitals of the carbon atoms extending normal to the graphene layers. We found that iron carbide particles incorporated as contamination during the mechanical milling also stored a significant amount of hydrogen, as revealed by the change in the Fe-L2,3 spectrum when the sample was annealed. We re-assigned the assumed hydrogen trapping sites to the hydrogen desorption peaks in the thermal desorption spectrum (TDS) based on these experimental results.

  18. Method for producing hydrogen and oxygen by use of algae

    DOEpatents

    Greenbaum, E.

    1982-06-16

    Efficiency of process for producing H/sub 2/ by subjecting algae in an aqueous phase to light irradiation is increased by culturing algae which has been bleached during a first period of irradiation in a culture medium in an aerobic atmosphere until it has regained color and then subjecting this algae to a second period of irradiation wherein hydrogen is produced at an enhanced rate.

  19. Method for producing hydrogen and oxygen by use of algae

    DOEpatents

    Greenbaum, Elias

    1984-01-01

    Efficiency of process for producing H.sub.2 by subjecting algae in an aqueous phase to light irradiation is increased by culturing algae which has been bleached during a first period of irradiation in a culture medium in an aerobic atmosphere until it has regained color and then subjecting this algae to a second period of irradiation wherein hydrogen is produced at an enhanced rate.

  20. The Rise of Oxygen and the Hydrogen Hourglass

    NASA Technical Reports Server (NTRS)

    Zahnle, Kevin; Catling, David C.; Claire, Mark W.

    2013-01-01

    Oxygenic photosynthesis appears to be necessary for an oxygen-rich atmosphere like Earth's. But available geological and geochemical evidence suggest that at least 200 Myr, and possibly more than 700 Myr, elapsed between the advent of oxygenic photosynthesis and the establishment of an oxygen atmosphere. The interregnum implies that at least one other necessary condition for O2 needed to be met. Here we argue that the second condition was the oxidation of the surface and crust to the point where O2 became more stable than competing reduced gases such as CH4. The cause of Earth's surface oxidation would be the same cause as it is for other planets with oxidized surfaces: hydrogen escape to space. The duration of the interregnum would have been determined by the rate of hydrogen escape and by the size of the reduced reservoir that needed to be oxidized before O2 became favored. We suggest that continental growth has been influenced by hydrogen escape, and we speculate that, if there must be an external bias to biological evolution, hydrogen escape can be that bias.

  1. HUBBLE CAPTURES DETAILED IMAGE OF URANUS' ATMOSPHERE

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Hubble Space Telescope has peered deep into Uranus' atmosphere to see clear and hazy layers created by a mixture of gases. Using infrared filters, Hubble captured detailed features of three layers of Uranus' atmosphere. Hubble's images are different from the ones taken by the Voyager 2 spacecraft, which flew by Uranus 10 years ago. Those images - not taken in infrared light - showed a greenish-blue disk with very little detail. The infrared image allows astronomers to probe the structure of Uranus' atmosphere, which consists of mostly hydrogen with traces of methane. The red around the planet's edge represents a very thin haze at a high altitude. The haze is so thin that it can only be seen by looking at the edges of the disk, and is similar to looking at the edge of a soap bubble. The yellow near the bottom of Uranus is another hazy layer. The deepest layer, the blue near the top of Uranus, shows a clearer atmosphere. Image processing has been used to brighten the rings around Uranus so that astronomers can study their structure. In reality, the rings are as dark as black lava or charcoal. This false color picture was assembled from several exposures taken July 3, 1995 by the Wide Field Planetary Camera-2. CREDIT: Erich Karkoschka (University of Arizona Lunar and Planetary Lab) and NASA

  2. First Super-Earth Atmosphere Analysed

    NASA Astrophysics Data System (ADS)

    2010-12-01

    absorbed. The team then compared these precise new measurements with what they would expect to see for several possible atmospheric compositions. Before the new observations, astronomers had suggested three possible atmospheres for GJ 1214b. The first was the intriguing possibility that the planet was shrouded by water, which, given the close proximity to the star, would be in the form of steam. The second possibility was that this is a rocky world with an atmosphere consisting mostly of hydrogen, but with high clouds or hazes obscuring the view. The third option was that this exoplanet was like a mini-Neptune, with a small rocky core and a deep hydrogen-rich atmosphere. The new measurements do not show the telltale signs of hydrogen and hence rule out the third option. Therefore, the atmosphere is either rich in steam, or it is blanketed by clouds or hazes, similar to those seen in the atmospheres of Venus and Titan in our Solar System, which hide the signature of hydrogen.. "Although we can't yet say exactly what that atmosphere is made of, it is an exciting step forward to be able to narrow down the options for such a distant world to either steamy or hazy," says Bean. "Follow-up observations in longer wavelength infrared light are now needed to determine which of these atmospheres exists on GJ 1214b." Notes [1] The number of confirmed exoplanets reached 500 on 19 November 2010. Since then, more exoplanets have been confirmed. For the latest count, please visit: http://exoplanet.eu/catalog.php [2] If GJ 1214 were seen at the same distance from us as our Sun, it would appear 300 times fainter. [3] Because the star GJ1214 itself is quite faint - more than 100 times fainter in visible light than the host stars of the two most widely studied hot Jupiter exoplanets - the large collecting area of the Very Large Telescope was critical for acquiring enough signal for these measurements. [4] GJ 1214b's atmospheric composition was studied using the FORS instrument on the Very

  3. Evolution of the atmosphere and oceans

    NASA Astrophysics Data System (ADS)

    Holland, H. D.; Lazar, B.; McCaffrey, M.

    1986-03-01

    The ocean-atmosphere system of the present and distant past are compared. The reservoirs and residence times of atmospheric and oceanic constituents and their input, output, and control mechanisms are discussed, showing that the residence times are small fractions of the age of the earth and that the rate of output is generally nearly equal to the rate of input. A number of these dynamic equilibria are being disturbed quite severely, especially the partial pressure of CO2. The major components of sea water, the isotopic composition of solutes in sea water, trace elements in sea water, and the atmospheric oxygen and CO2 through the earth's history are discussed. No drastic changes have occurred in the composition of sea water during the last 900 Myr. The chemistry of soils formed more than 1000 Myr ago suggests that the atmosphere then contained significantly more CO2 and less O2 than at present. Hydrogen peroxide may have been the principal oxidant and formaldehyde the main reductant in rain water between 3000 and 1000 Myr ago.

  4. Wet-Atmosphere Generator

    NASA Technical Reports Server (NTRS)

    Hamner, Richard M.; Mcguire, Janice K.

    1988-01-01

    Water content in gas controlled. Portable flow-control system generates nitrogen/water atmosphere having range of dew points and pressures. One use of system provides wet nitrogen for canister of wide-field camera requiring this special atmosphere. Also used to inject trace gases other than water vapor for leak testing of large vessels. Potential applications in photography, hospitals, and calibration laboratories.

  5. MODIS Atmospheric Data Handler

    NASA Technical Reports Server (NTRS)

    Anantharaj, Valentine; Fitzpatrick, Patrick

    2008-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) Atmosphere Data Handler software converts the HDF data to ASCII format, and outputs: (1) atmospheric profiles of temperature and dew point and (2) total precipitable water. Quality-control data are also considered in the export procedure.

  6. Magneto-atmospheric waves

    NASA Technical Reports Server (NTRS)

    Thomas, J. H.

    1983-01-01

    A theoretical treatment of magneto-atmospheric waves is presented and applied to the modelling of waves in the solar atmosphere. The waves arise in compressible, stratified, electrically conductive atmospheres within gravitational fields when permeated by a magnetic field. Compression, buoyancy, and distortion of the magnetic field all contribute to the existence of the waves. Basic linearized equations are introduced to describe the waves and attention is given to plane-stratified atmospheres and their stability. A dispersion relation is defined for wave propagation in a plane-stratified atmosphere when there are no plane-wave solutions. Solutions are found for the full wave equation in the presence of either a vertical or a horizontal magnetic field. The theory is applied to describing waves in sunspots, in penumbrae, and flare-induced coronal disturbances.

  7. Atmosphere Impact Losses

    NASA Astrophysics Data System (ADS)

    Schlichting, Hilke E.; Mukhopadhyay, Sujoy

    2018-02-01

    Determining the origin of volatiles on terrestrial planets and quantifying atmospheric loss during planet formation is crucial for understanding the history and evolution of planetary atmospheres. Using geochemical observations of noble gases and major volatiles we determine what the present day inventory of volatiles tells us about the sources, the accretion process and the early differentiation of the Earth. We further quantify the key volatile loss mechanisms and the atmospheric loss history during Earth's formation. Volatiles were accreted throughout the Earth's formation, but Earth's early accretion history was volatile poor. Although nebular Ne and possible H in the deep mantle might be a fingerprint of this early accretion, most of the mantle does not remember this signature implying that volatile loss occurred during accretion. Present day geochemistry of volatiles shows no evidence of hydrodynamic escape as the isotopic compositions of most volatiles are chondritic. This suggests that atmospheric loss generated by impacts played a major role during Earth's formation. While many of the volatiles have chondritic isotopic ratios, their relative abundances are certainly not chondritic again suggesting volatile loss tied to impacts. Geochemical evidence of atmospheric loss comes from the {}3He/{}^{22}Ne, halogen ratios (e.g., F/Cl) and low H/N ratios. In addition, the geochemical ratios indicate that most of the water could have been delivered prior to the Moon forming impact and that the Moon forming impact did not drive off the ocean. Given the importance of impacts in determining the volatile budget of the Earth we examine the contributions to atmospheric loss from both small and large impacts. We find that atmospheric mass loss due to impacts can be characterized into three different regimes: 1) Giant Impacts, that create a strong shock transversing the whole planet and that can lead to atmospheric loss globally. 2) Large enough impactors (m_{cap} ≳ √{2

  8. Atmospheric Fluorescence Yield

    NASA Technical Reports Server (NTRS)

    Adams, James H., Jr.; Christl, M. J.; Fountain, W. F.; Gregory, J. C.; Martens, K.; Sokolsky, P.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Several existing and planned experiments estimate the energies of ultra-high energy cosmic rays from air showers using the atmospheric fluorescence from these showers. Accurate knowledge of the conversion from atmospheric fluorescence to energy loss by ionizing particles in the atmosphere is key to this technique. In this paper we discuss a small balloon-borne instrument to make the first in situ measurements versus altitude of the atmospheric fluorescence yield. The instrument can also be used in the lab to investigate the dependence of the fluorescence yield in air on temperature, pressure and the concentrations of other gases that present in the atmosphere. The results can be used to explore environmental effects on and improve the accuracy of cosmic ray energy measurements for existing ground-based experiments and future space-based experiments.

  9. The Atmosphere Below

    NASA Technical Reports Server (NTRS)

    1992-01-01

    In this educational 'Liftoff to Learning' video series, astronauts from the STS-45 Space Shuttle Mission (Kathy Sullivan, Byron Lichtenberg, Brian Duffy, Mike Foale, David Leestma, Charlie Bolden, and Dirk Frimont) explain and discuss the Earths atmosphere, its needs, the changes occurring within it, the importance of ozone, and some of the reasons behind the ozone depletion in the Earths atmosphere. The questions of: (1) what is ozone; (2) what has happened to the ozone layer in the atmosphere; and (3) what exactly does ozone do in the atmosphere, are answered. Different chemicals and their reactions with ozone are discussed. Computer animation and graphics show how these chemical reactions affect the atmosphere and how the ozone hole looks and develops at the south pole during its winter season appearance.

  10. Titan's Lower Atmosphere

    NASA Astrophysics Data System (ADS)

    Griffith, Caitlin Ann

    2007-09-01

    Saturn's largest moon, Titan, sports an atmosphere 10 times thicker than Earth's. Like Earth, the moon's atmosphere is N2 based and possesses a rich organic chemistry. In addition, similar to the terrestrial hydrological cycle, Titan has a methane cycle, with methane clouds, rain and seas. Presently, there is a revolution in our understanding of the moon, as data flows in and is analyzed from the NASA and ESA Cassini-Huygens mission. For example, seas were detected only this year. Here I will discuss the evolution of our understanding of Titan's atmosphere, its composition, chemistry, dynamics and origin. Current open questions will also be presented. Studies of Titan's atmosphere began and evolved to the present state in less time than that of a single scientist's career. This short interlude of activity demonstrates the rigors of the scientific method, and raises enticing questions about the workings and evolution of an atmosphere.

  11. Introduction to Atmospheric Chemistry

    NASA Astrophysics Data System (ADS)

    Thompson, Anne M.

    In thirty years of university teaching, Peter Hobbs of the Atmospheric Sciences Department at the University of Washington, has seen atmospheric chemistry grow from a relatively small branch of geosciences into one with which every student of atmospheric sciences needs familiarity Some students are captivated in their first course and make atmospheric chemistry a field of further study or a lifelong career. At the same time, courses of “global change” and emerging curricula in scientific policy require students from diverse backgrounds to develop sufficient knowledge to become well-informed policy-makers. A number of practicing atmospheric chemists are retrained on the job from other scientific backgrounds and need selfeducation in the basics of the field.

  12. Biomimetic Production of Hydrogen

    NASA Astrophysics Data System (ADS)

    Gust, Devens

    2004-03-01

    The basic reaction for hydrogen generation is formation of molecular hydrogen from two electrons and two protons. Although there are many possible sources for the protons and electrons, and a variety of mechanisms for providing the requisite energy for hydrogen synthesis, the most abundant and readily available source of protons and electrons is water, and the most attractive source of energy for powering the process is sunlight. Not surprisingly, living systems have evolved to take advantage of these sources for materials and energy. Thus, biology provides paradigms for carrying out the reactions necessary for hydrogen production. Photosynthesis in green plants uses sunlight as the source of energy for the oxidation of water to give molecular oxygen, protons, and reduction potential. Some photosynthetic organisms are capable of using this reduction potential, in the form of the reduced redox protein ferredoxin, to reduce protons and produce molecular hydrogen via the action of an hydrogenase enzyme. A variety of other organisms metabolize the reduced carbon compounds that are ultimately the major products of photosynthesis to produce molecular hydrogen. These facts suggest that it might be possible to use light energy to make molecular hydrogen via biomimetic constructs that employ principles similar to those used by natural organisms, or perhaps with hybrid "bionic" systems that combine biomimetic materials with natural enzymes. It is now possible to construct artificial photosynthetic systems that mimic some of the major steps in the natural process.(1) Artificial antennas based on porphyrins, carotenoids and other chromophores absorb light at various wavelengths in the solar spectrum and transfer the harvested excitation energy to artificial photosynthetic reaction centers.(2) In these centers, photoinduced electron transfer uses the energy from light to move an electron from a donor to an acceptor moiety, generating a high-energy charge-separated state

  13. Hydrogen transport and hydrogen embrittlement in stainless steels

    SciTech Connect

    Perng, T.P.

    1985-01-01

    In order to understand the kinetics of gaseous hydrogen-induced slow crack growth (SCG) in metastable austenitic stainless steels, hydrogen permeation and/or cracking velocity were measured and compared for three types of stainless steels. These included austenitic, ferritic, and duplex (..gamma../..cap alpha..) alloys. Deformation in AISI 301 resulted in various amounts of ..cap alpha..' martensite, which enhanced the effective hydrogen diffusivity and permeability. No phase transformation was observed in deformed AISI 310. The effective hydrogen diffusivity in this alloy was slightly reduced after plastic deformation, presumably by dislocation trapping. In either the dynamic or static tensile test, AISI 301 exhibited themore » greatest hydrogen embrittlement and therefore the highest SCG velocity among all the alloys tested in this work. The SCG velocity was believed to be controlled by the rate of accumulation of hydrogen in the embrittlement region ahead of the crack tip and therefore could be explained with the hydrogen transport parameters measured from the permeation experiments. The relatively high SCG velocity in AISI 301 was probably due to the fast transport of hydrogen through the primarily stress-induced ..cap alpha..' phase around the crack. No SCG was observed in AISI 310. The presence of H/sub 2/O vapor was found to reduce both the hydrogen permeation and SCG velocity.« less

  14. Geochemical cycles of atmospheric gases

    NASA Technical Reports Server (NTRS)

    Walker, J. C. G.; Drever, J. I.

    1988-01-01

    The processes that control the atmosphere and atmospheric changes are reviewed. The geochemical cycles of water vapor, nitrogen, carbon dioxide, oxygen, and minor atmospheric constituents are examined. Changes in atmospheric chemistry with time are discussed using evidence from the rock record and analysis of the present atmosphere. The role of biological evolution in the history of the atmosphere and projected changes in the future atmosphere are considered.

  15. Hydrogen and helium excitation by EUV radiation for the production of white-light flares

    NASA Technical Reports Server (NTRS)

    Poland, A. I.; Milkey, R. W.; Thompson, W. T.

    1988-01-01

    Non-LTE radiative transfer calculations for hydrogen and helium in a simple model atmosphere are used to demonstrate that EUV radiation cannot be the main energy source for white-light flares. The opacities in the Lyman continuum and the helium I and II continua are found to be much larger than the enhanced opacity in the visible hydrogen continuum. It is shown that the EUV radiation is absorbed before it can have a significant effect on the visible light continuum.

  16. Titan's atmosphere and climate

    NASA Astrophysics Data System (ADS)

    Hörst, S. M.

    2017-03-01

    Titan is the only moon with a substantial atmosphere, the only other thick N2 atmosphere besides Earth's, the site of extraordinarily complex atmospheric chemistry that far surpasses any other solar system atmosphere, and the only other solar system body with stable liquid currently on its surface. The connection between Titan's surface and atmosphere is also unique in our solar system; atmospheric chemistry produces materials that are deposited on the surface and subsequently altered by surface-atmosphere interactions such as aeolian and fluvial processes resulting in the formation of extensive dune fields and expansive lakes and seas. Titan's atmosphere is favorable for organic haze formation, which combined with the presence of some oxygen-bearing molecules indicates that Titan's atmosphere may produce molecules of prebiotic interest. The combination of organics and liquid, in the form of water in a subsurface ocean and methane/ethane in the surface lakes and seas, means that Titan may be the ideal place in the solar system to test ideas about habitability, prebiotic chemistry, and the ubiquity and diversity of life in the universe. The Cassini-Huygens mission to the Saturn system has provided a wealth of new information allowing for study of Titan as a complex system. Here I review our current understanding of Titan's atmosphere and climate forged from the powerful combination of Earth-based observations, remote sensing and in situ spacecraft measurements, laboratory experiments, and models. I conclude with some of our remaining unanswered questions as the incredible era of exploration with Cassini-Huygens comes to an end.

  17. Hydrogen Permeability of Incoloy 800H, Inconel 617, and Haynes 230 Alloys

    SciTech Connect

    Pattrick Calderoni

    2010-07-01

    A potential issue in the design of the NGNP reactor and high-temperature components is the permeation of fission generated tritium and hydrogen product from downstream hydrogen generation through high-temperature components. Such permeation can result in the loss of fission-generated tritium to the environment and the potential contamination of the helium coolant by permeation of product hydrogen into the coolant system. The issue will be addressed in the engineering design phase, and requires knowledge of permeation characteristics of the candidate alloys. Of three potential candidates for high-temperature components of the NGNP reactor design, the hydrogen permeability has been documented well onlymore » for Incoloy 800H, but at relatively high partial pressures of hydrogen. Hydrogen permeability data have been published for Inconel 617, but only in two literature reports and for partial pressures of hydrogen greater than one atmosphere, far higher than anticipated in the NGNP reactor. The hydrogen permeability of Haynes 230 has not been published. To support engineering design of the NGNP reactor components, the hydrogen permeability of Inconel 617 and Haynes 230 were determined using a measurement system designed and fabricated at the Idaho National Laboratory. The performance of the system was validated using Incoloy 800H as reference material, for which the permeability has been published in several journal articles. The permeability of Incoloy 800H, Inconel 617 and Haynes 230 was measured in the temperature range 650 to 950 °C and at hydrogen partial pressures of 10-3 and 10-2 atm, substantially lower pressures than used in the published reports. The measured hydrogen permeability of Incoloy 800H and Inconel 617 were in good agreement with published values obtained at higher partial pressures of hydrogen. The hydrogen permeability of Inconel 617 and Haynes 230 were similar, about 50% greater than for Incoloy 800H and with similar temperature dependence.« less

  18. Atmospheric Mining in the Outer Solar System: Resource Capturing, Exploration, and Exploitation

    NASA Technical Reports Server (NTRS)

    Palaszewski, Bryan

    2015-01-01

    Atmospheric mining in the outer solar system (AMOSS) has been investigated as a means of fuel production for high-energy propulsion and power. Fusion fuels such as helium 3 (He-3) and hydrogen can be wrested from the atmospheres of Uranus and Neptune and either returned to Earth or used in-situ for energy production. 3He and hydrogen (deuterium, etc.) were the primary gases of interest, with hydrogen being the primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of analyses were undertaken to investigate resource capturing aspects of AMOSS. These analyses included the gas capturing rate, storage options, and different methods of direct use of the captured gases. Additional supporting analyses were conducted to illuminate vehicle sizing and orbital transportation issues. While capturing 3He, large amounts of hydrogen and helium 4 (He-4) are produced. With these two additional gases, the potential exists for fueling small and large fleets of additional exploration and exploitation vehicles. Additional aerospacecraft or other aerial vehicles (UAVs, balloons, rockets, etc.) could fly through the outer-planet atmosphere to investigate cloud formation dynamics, global weather, localized storms or other disturbances, wind speeds, the poles, and so forth. Deep-diving aircraft (built with the strength to withstand many atmospheres of pressure) powered by the excess hydrogen or 4He may be designed to probe the higher density regions of the gas giants.

  19. A study of alternative designs for a system to concentrate carbon dioxide in a hydrogen-depolarized cell

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Experimental results are presented on alternative designs for a hydrogen depolarized cell to concentrate CO2 in spacecraft atmospheric control systems. Data cover technical problems, methods for solving these problems, and the suitability of such a cell for CO2 removal and control of atmospheric humidity during the flight mode.

  20. Trapping and spectroscopy of hydrogen

    NASA Astrophysics Data System (ADS)

    Cesar, Claudio Lenz

    1997-08-01

    I review the results and techniques used by the MIT H↑ group to achieve a fractional resolution of 2 parts in 1012 in the 1S-2S transition in hydrogen [Cesar, D. Fried, T. Killian, A. Polcyn, J. Sandberg, I.A. Yu, T. Greytak, D. Kleppner and J. Doyle, Two-photon spectroscopy of trapped atomic hydrogen, Phys. Rev. Lett. 77 (1996) 255.] With some improvements, this system should deliver 100 times higher resolution with an improved signal count rate getting us closer to an old advertised goal of a precision of 1 part in 1018. While these developments are very important for the proposed test of the CPT theorem through the comparison with anti-hydrogen, some of the techniques used with hydrogen are not applicable to anti-hydrogen and I discuss some difficulties and alternatives for the trapping and spectroscopy of anti-hydrogen.