Sample records for hydrogen deuterium carbon

  1. Adsorption kinetics and energetics of atomic hydrogen (deuterium) on oxygen and carbon covered V(100)

    NASA Astrophysics Data System (ADS)

    Krenn, G.; Eibl, C.; Mauritsch, W.; Hebenstreit, E. L. D.; Varga, P.; Winkler, A.

    2000-01-01

    The interaction of atomic and to some extent molecular hydrogen (deuterium) with oxygen and carbon covered V(100) surfaces has been studied. The oxygen and carbon coverage has been well characterized with respect to composition and structure by low energy electron diffraction (LEED), Auger electron spectroscopy (AES) and scanning tunneling microscopy (STM). Thermal desorption spectroscopy (TDS) has been used to investigate the kinetics of adsorption, absorption and desorption quantitatively. In addition, the activation barriers for the individual reaction steps during adsorption and desorption have been determined. We have focused on the advantage of using atomic hydrogen to enhance the uptake of hydrogen into the bulk of a contaminated vanadium sample. Surface, subsurface and bulk sites are occupied upon exposure to the atomic H (D) even at a surface temperature of 90 K. These adsorption states exhibit desorption peaks at 150 K (?-state), between 200 and 500 K (?-states), and at 1000 K (?-state). The corresponding desorption energies are 0.36 eV, 0.4-1.1 eV, and 0.9 eV, respectively. The kinetics of adsorption and absorption for molecular hydrogen depend strongly on the chemical composition of the surface, whereas the interaction of atomic hydrogen (deuterium) with V(100) is much less influenced by surface contaminants.

  2. Rosenbluth Separation of the pion electroproduction cross section from Hydrogen, Deuterium, Carbon and Copper targets

    NASA Astrophysics Data System (ADS)

    Qian, Xin; Clasie, Ben; Dutta, Dipangkar; Gao, Haiyan

    2006-10-01

    Pion electroproduction data was collected from six targets, including hydrogen, deuterium, carbon and copper, in Jefferson Lab experiment E01-107. The primary motivation of this experiment is to search for signatures of a phenomenon predicted by perturbative quantum chromodynamics (pQCD) known as Color Transparency (CT). In this experiment the nuclear transparency of pions is extracted by using the ratio of semi-exclusive pion electroproduction from nuclear targets to the same from a hydrogen target. This method relies on the assumption that the reaction mechanism of electropion production from hydrogen is similar to the quasi-free eletropion production from nuclear targets. This assumption can tested by performing a Longitudinal-Transverse (L-T) separation of the pion electroproduction cross section and comparing the separated cross sections from hydrogen to that from heavier targets. In order to perform an L-T separation, data were collected at forward and backward electron angles at fixed momentum transfer squared (Q^2), for Q^2=2.15 and 4.0 GeV^2/c^2, which were chosen to fall within the Q^2 range over which the nuclear transparency is extracted. The extracted longitudinal and transverse cross sections at the two Q^2 settings from hydrogen, deuterium, carbon and copper targets will be presented.

  3. Adsorption of nitrogen, hydrogen, and deuterium on carbon nanotubes bundles

    Microsoft Academic Search

    Oscar E. Vilches; Adam Tyburski; Tate Wilson; Matt Depies; Daphne Becquet; Michel Bienfait

    2001-01-01

    Adsorption isotherm measurements on bundles of closed ends carbon nanotubes will be reported, for temperatures between 77K and 96K for N2, H2, and D2, and between 28K and 40K for H2 and D2. Results show the two broad coverage vs. pressure steps reported by Migone's group [S.E.Weber et al., Phys. Rev. B61, 13150 (2000)] and Bienfait's group [M.Muris et al.,

  4. Adsorption of nitrogen, hydrogen, and deuterium on carbon nanotubes bundles

    NASA Astrophysics Data System (ADS)

    Vilches, Oscar E.; Tyburski, Adam; Wilson, Tate; Depies, Matt; Becquet, Daphne; Bienfait, Michel

    2001-03-01

    Adsorption isotherm measurements on bundles of closed ends carbon nanotubes will be reported, for temperatures between 77K and 96K for N2, H2, and D2, and between 28K and 40K for H2 and D2. Results show the two broad coverage vs. pressure steps reported by Migone's group [S.E.Weber et al., Phys. Rev. B61, 13150 (2000)] and Bienfait's group [M.Muris et al., Langmuir 16, 7019 (2000)] for other adsorbates using similar substrates. The calculated isosteric heat from the lower coverage step is about twice the isosteric heat of the higher coverage step for each of the molecules, with this higher step having somewhat smaller binding energy than the same molecules on graphite.

  5. Analysis of hydrogen and deuterium in carbon films on the wall of JIPP T-IIU tokamak

    Microsoft Academic Search

    N. Noda; H. Minagawa; S. Amemiya; K. Ishikawa; S. Hirokura; Y. Hori; R. Akiyama; T. Yamashina; T. Satake

    1987-01-01

    In situ carbon coating was carried out with a glow discharge in methane-hydrogen mixtures on the wall of the JIPP T-IIU tokamak at room temperature. The concentration of hydrogen and deuterium in C-films was analyzed by thermal desorption spectroscopy (TDS) and elastic recoil detection analysis (ERDA). Good agreement was obtained between results deduced from these two methods. Hydrogen concentration is

  6. Cryogenic tritium-hydrogen-deuterium and deuterium-tritium layer implosions with high density carbon ablators in near-vacuum hohlraums

    NASA Astrophysics Data System (ADS)

    Meezan, N. B.; Berzak Hopkins, L. F.; Le Pape, S.; Divol, L.; MacKinnon, A. J.; Döppner, T.; Ho, D. D.; Jones, O. S.; Khan, S. F.; Ma, T.; Milovich, J. L.; Pak, A. E.; Ross, J. S.; Thomas, C. A.; Benedetti, L. R.; Bradley, D. K.; Celliers, P. M.; Clark, D. S.; Field, J. E.; Haan, S. W.; Izumi, N.; Kyrala, G. A.; Moody, J. D.; Patel, P. K.; Ralph, J. E.; Rygg, J. R.; Sepke, S. M.; Spears, B. K.; Tommasini, R.; Town, R. P. J.; Biener, J.; Bionta, R. M.; Bond, E. J.; Caggiano, J. A.; Eckart, M. J.; Gatu Johnson, M.; Grim, G. P.; Hamza, A. V.; Hartouni, E. P.; Hatarik, R.; Hoover, D. E.; Kilkenny, J. D.; Kozioziemski, B. J.; Kroll, J. J.; McNaney, J. M.; Nikroo, A.; Sayre, D. B.; Stadermann, M.; Wild, C.; Yoxall, B. E.; Landen, O. L.; Hsing, W. W.; Edwards, M. J.

    2015-06-01

    High Density Carbon (or diamond) is a promising ablator material for use in near-vacuum hohlraums, as its high density allows for ignition designs with laser pulse durations of <10 ns. A series of Inertial Confinement Fusion (ICF) experiments in 2013 on the National Ignition Facility [Moses et al., Phys. Plasmas 16, 041006 (2009)] culminated in a deuterium-tritium (DT) layered implosion driven by a 6.8 ns, 2-shock laser pulse. This paper describes these experiments and comparisons with ICF design code simulations. Backlit radiography of a tritium-hydrogen-deuterium (THD) layered capsule demonstrated an ablator implosion velocity of 385 km/s with a slightly oblate hot spot shape. Other diagnostics suggested an asymmetric compressed fuel layer. A streak camera-based hot spot self-emission diagnostic (SPIDER) showed a double-peaked history of the capsule self-emission. Simulations suggest that this is a signature of low quality hot spot formation. Changes to the laser pulse and pointing for a subsequent DT implosion resulted in a higher temperature, prolate hot spot and a thermonuclear yield of 1.8 × 1015 neutrons, 40% of the 1D simulated yield.

  7. Vibrational circular dichroism in the carbon-hydrogen and carbon-deuterium stretching modes of (S,S)-(2,3-/sup 2/H/sub 2/)oxirane

    SciTech Connect

    Freedman, T.B.; Paterlini, M.G.; Lee, N.; Nafie, L.A.

    1987-07-22

    The authors report vibrational circular dichroism (VCD) spectra of (S,S)-(2,3-/sup 2/H/sub 2/)oxirane in the carbon-hydrogen and carbon-deuterium stretching regions. Three- and four-membered chiral ring molecules have been the focus of several previous VCD studies owing to their conformational rigidity, low molecular weight, and the relative simplicity of their vibrational spectra. The chiral oxirane featured in this study is the smallest and simplest molecule for which VCD has been observed to date. The observed VCD spectra are correspondingly simple, consisting of a bisignate couplet in each spectral region corresponding to the in-phase and out-of-phase hydrogen, or deuterium, stretching modes. The general features of the couplets are readily interpreted in terms of the coupled oscillator and rig current intensity mechanisms as well as theoretical vibronic coupling calculations. The significance of the reported VCD spectra is that they provide the experimental basis for comparison to the results of the most sophisticated theoretical calculations which can be performed for a molecule as large as oxirane.

  8. Deuterium retention in carbon flakes and tungsten carbon mixed flakes produced by deuterium arc discharge

    NASA Astrophysics Data System (ADS)

    Hino, T.; Yoshida, H.; Akiba, M.; Suzuki, S.; Hirohata, Y.; Yamauchi, Y.; Nakamura, K.

    2005-08-01

    In order to estimate the in-vessel tritium inventory of carbon flakes or dust, deuterium gas absorption and deuterium ion irradiation experiments were conducted on carbon flakes prepared by using electron beam evaporation of graphite. The retained amount of deuterium after the deuterium gas absorption was very low; D/C = 10-3 atomic ratio. The retained amount of deuterium after the deuterium ion irradiation was very similar when compared with that for graphite. The deuterium concentration of the carbon flakes resulting from ion irradiation becomes close to zero if the wall temperature is higher than 1000 K. Co-deposited carbon flakes were prepared by a deuterium arc discharge with carbon electrodes at different gas pressures and substrate temperatures. The co-deposited carbon flakes had a high deuterium concentration. Under such conditions with gas pressure of 1 Pa and wall temperature of 573 K, the deuterium concentration becomes approximately D/C = 0.2. In a DT fusion device like ITER, we therefore, expect a T/C ratio of 0.1. This value is presumed to be an upper limit of carbon flakes in ITER since the wall temperature may be higher than 573 K. Tungsten-carbon mixed flakes were also produced by the deuterium arc discharge with carbon and tungsten electrodes. The deuterium was trapped mainly in the carbon atoms and the structure of carbon in the tungsten-carbon mixed flakes was more amorphous compared with that of the co-deposited carbon flakes. Then, the deuterium concentration was higher than that of the carbon flakes, and increased with the increase in the concentration of tungsten. The higher concentration in the tungsten-carbon mixed flakes may not affect the in-vessel tritium inventory if the tungsten concentration is low.

  9. Atomic Deuterium/Hydrogen in the Galaxy

    E-print Network

    Jeffrey L. Linsky

    2003-09-03

    An accurate value of the deuterium/hydrogen (D/H) ratio in the local interstellar medium (LISM) and a better understanding of the D/H variations with position in the Galactic disk can provide essential information on the primordial D/H ratio in the Galaxy at the time of the protosolar nebula, and the amount of astration and mixing in the Galaxy over time. Recent measurements have been obtained with UV spectrographs on FUSE, HST, and IMAPS using hot white dwarfs, OB stars, and late-type stars as background light sources against which to measure absorption by D and H in the interstellar medium along the lines of sight. Recent analyses of FUSE observations of seven white dwarfs and subdwarfs provide a weighted mean value of D/H = (1.52 +/- 0.08) 10(-5) (15.2 +/- 0.8 ppm), consistent with the value of (1.50 +/- 0.10) 10(-5) (15.0 +/- 1.0 ppm) obtained from analysis of lines of sight toward nearby late-type stars. Both numbers refer to the ISM within about 100 pc of the Sun, which samples warm clouds located within the Local Bubble. Outside of the Local Bubble at distances of 200 to 500 pc, analyses of far-UV spectra obtained with IMAPS indicate a much wider range of D/H ratios between 0.8 to 2.2 ppm, providing information on inhomogeneous astration in the Galactic disk.

  10. Deuterium Uptake in Magnetic-Fusion Devices with Lithium-Conditioned Carbon Walls

    SciTech Connect

    Krstic, Predrag S. [University of Tennessee (UTK) and Oak Ridge National Laboratory (ORNL); Allain, J. P. [Purdue University; Taylor, C. N. [Purdue University; Dadras, J. [UTK/Univ. California, Los Angeles; Maeda, S. [Kyoto University, Fukui Institute for Fundamental Chemistry, Japan; Morokuma, K. [Kyoto University, Fukui Institute for Fundamental Chemistry, Japan; Jakowski, J. [National Inst. Computational Sciences, UTK; Allouche, A. [PIM/CNRS/Aix-Marseille University, Marseille, France; Baylor, Larry R [ORNL; Skinner, C. H. [Princeton Plasma Physics Laboratory (PPPL)

    2013-01-01

    Lithium wall conditioning has lowered hydrogenic recycling and dramatically improved plasma performance in many magnetic-fusion devices. In this Letter, we report quantum-classical atomistic simulations and laboratory experiments that elucidate the roles of lithium and oxygen in the uptake of hydrogen in amorphous carbon. Surprisingly, we show that lithium creates a high oxygen concentration on a carbon surface when bombarded by deuterium. Furthermore, surface oxygen, rather than lithium, plays the key role in trapping hydrogen.

  11. Appendix A SIMS profiles of hydrogen and deuterium in diamond

    E-print Network

    Goddard III, William A.

    127 Appendix A SIMS profiles of hydrogen and deuterium in diamond A.1 Introduction A diamond sample ion­beam doping. Impurity levels were profiled as a function of depth from the diamond surface using­type reactor, consisting of a quartz tube with diamond­coated quartz substrate holder. The substrate

  12. Comparison of the dynamics of hydrogen and deuterium dissolved in

    Microsoft Academic Search

    T. J. Udovic; C. Karmonik; Q. Huang; J. J. Rush; M. Vennstrom; Y. Andersson; T. B. Flanagan

    The bonding potentials of hydrogen and deuterium dissolved in the crystalline alloys Pd Si and Pd P have been studied by neutron 9 2 3 0.8 scattering techniques. Neutron powder diffraction verifies that, in both alloys, the principal type of interstitial absorption site is the quadrilateral base of a Pd-defined pyramid situated on the face of an empty triangular prism.

  13. Ordered ground states of metallic hydrogen and deuterium

    NASA Technical Reports Server (NTRS)

    Ashcroft, N. W.

    1981-01-01

    The physical attributes of some of the more physically distinct ordered states of metallic hydrogen and metallic deuterium at T = 0 and nearby are discussed. The likelihood of superconductivity in both is considered with respect to the usual coupling via the density fluctuations of the ions.

  14. Deuterium trapping in carbon fiber composites exposed to D plasma

    NASA Astrophysics Data System (ADS)

    Airapetov, A.; Begrambekov, L.; Brosset, C.; Gunn, J. P.; Grisolia, C.; Kuzmin, A.; Loarer, T.; Lipa, M.; Monier-Garbet, P.; Shigin, P.; Tsitrone, E.; Zakharov, A.

    2009-06-01

    Deuterium trapping in carbon fiber composite N11 and pyrolitic graphite PG99 irradiated with plasma ions and electrons was examined with thermal desorption spectrometry. It has been found that the deuterium trapping takes place even at ion and electron energies of about 10 eV. For equal ion fluences, the deuterium retention and probability of CD 4 formation are higher for ion irradiation at lower ion flux. Peculiarities of the deuterium retention and CD 4 formation are explained; driving forces and mechanisms of the D trapping are discussed.

  15. The Blast Experiment:. Polarized Electron Scattering from Hydrogen and Deuterium

    NASA Astrophysics Data System (ADS)

    Alarcon, R.

    At the MIT-Bates Linear Accelerator Center, the nucleon form factors have been measured by scattering polarized electrons from vector-polarized hydrogen and deuterium. The experiment used the longitudinally polarized electron beam stored in the MIT-Bates South Hall Ring along with an isotopically pure, highly vector-polarized internal atomic hydrogen and deuterium target provided by an atomic beam source. The measurements were carried out with the symmetric Bates Large Acceptance Spectrometer Toroid (BLAST). Results are presented for the proton form factor ratio, ? p GEp/G_M^p, and for the charge form factor of the neutron, GEn. Both results are more precise than previous data in the corresponding Q2 ranges.

  16. Equations of state for hydrogen and deuterium.

    SciTech Connect

    Kerley, Gerald Irwin (Kerley Technical Services, Appomattox, VA)

    2003-12-01

    This report describes the complete revision of a deuterium equation of state (EOS) model published in 1972. It uses the same general approach as the 1972 EOS, i.e., the so-called 'chemical model,' but incorporates a number of theoretical advances that have taken place during the past thirty years. Three phases are included: a molecular solid, an atomic solid, and a fluid phase consisting of both molecular and atomic species. Ionization and the insulator-metal transition are also included. The most important improvements are in the liquid perturbation theory, the treatment of molecular vibrations and rotations, and the ionization equilibrium and mixture models. In addition, new experimental data and theoretical calculations are used to calibrate certain model parameters, notably the zero-Kelvin isotherms for the molecular and atomic solids, and the quantum corrections to the liquid phase. The report gives a general overview of the model, followed by detailed discussions of the most important theoretical issues and extensive comparisons with the many experimental data that have been obtained during the last thirty years. Questions about the validity of the chemical model are also considered. Implications for modeling the 'giant planets' are also discussed.

  17. HYDROGEN AND DEUTERIUM NMR OF SOLIDS BY MAGIC ANGLE SPINNING

    SciTech Connect

    Eckman, R.R.

    1982-10-01

    The nuclear magnetic resonance of solids has long been characterized by very large spectral broadening which arises from internuclear dipole-dipole coupling or the nuclear electric quadrupole interaction. These couplings can obscure the smaller chemical shift interaction and make that information unavailable. Two important and difficult cases are that of hydrogen and deuterium. For example, the homonuclear dipolar broadening, HD, for hydrogen is usually several tens of kilohertz. For deuterium, HD is relatively small; however, the quadrupole interaction causes a broadening which can be hundreds of kilohertz in polycrystalline or amorphous solids. The development of cross polarization, heteronuclear radiofrequency decoupling, and coherent averaging of nuclear spin interactions has provided measurement of chemical shift tensors in solids. Recently, double quantum NMR and double quantum decoupling have led to measurement of deuterium and proton chemical shift tensors, respectively. A general problem of these experiments is the overlapping of the tensor powder pattern spectra of magnetically distinct sites which cannot be resolved. In this work, high resolution NMR of hydrogen and deuterium in solids is demonstrated. For both nuclei, the resonances are narrowed to obtain liquid-like isotropic spectra by high frequency rotation of the sample about an axis inclined at the magic angle, {beta}{sub m} = Arccos(3{sup -1/2}), with respect to the direction of the external magnetic field. Two approaches have been developed for each nucleus. For deuterium, the powder spectra were narrowed by over three orders of magnitude by magic angle rotation with precise control of {beta}. A second approach was the observation of deuterium double quantum transitions under magic angle rotation. For hydrogen, magic angle rotation alone could be applied to obtain the isotropic spectrum when H{sub D} was small. This often occurs naturally when the nuclei are semi-dilute or involved in internal motion. In the general case of large H{sub D}, isotropic spectra were obtained by dilution of {sup 1}H with {sup 2}H combined with magic angle rotation. The resolution obtained represents the practical limit for proton NMR of solids. Theoretical and technical aspects are described in the text with comments on the application of the principles to other nuclei of interest.

  18. Isentropes and Hugoniot curves for dense hydrogen and deuterium

    SciTech Connect

    Beule, Dieter; Ebeling, Werner; Forster, Andreas; Juranek, Hauke; Redmer, Ronald; Ropke, Gerd

    2001-06-01

    Multiple-shock experiments with fluid hydrogen have shown that a transition from semiconducting behavior to metal-like conductivity occurs at pressures (p) of about 140 GPa and temperatures (T) near 3000 K. We model the p-T pathway by Hugoniot curves (initial shock) and isentropes (subsequent shocks). For the calculation of these curves we apply an expression for the free energy developed recently for dense hydrogen and deuterium plasma in the regions of partial dissociation and partial ionization. Furthermore, we discuss the relations between Hugoniot curves, isentropes and the coexistence line of the plasma phase transition.

  19. Lattice expansion of niobium and tantalum due to dissolved hydrogen and deuterium

    Microsoft Academic Search

    H. Pfeiffer; H. Peisl

    1977-01-01

    The volume change of niobium and tantalum due to interstitially dissolved hydrogen and deuterium has been determined by means of X-ray Bragg scattering. The volume increase in niobium is the same for hydrogen and deuterium deltanu=(0.174+\\/-0.005)Omega(Omega: atomic volume). A small isotope effect has been observed in the case of tantalum, Deltanu=(0.155+\\/-0.002) Omega for hydrogen and Deltanu=(0.143+\\/-0.005)Omega for deuterium.

  20. Effects of chemical states of carbon on deuterium retention in carbon-containing materials

    NASA Astrophysics Data System (ADS)

    Oyaidzu, Makoto; Kimura, Hiromi; Nakahata, Toshihiko; Nishikawa, Yusuke; Tokitani, Masayuki; Oya, Yasuhisa; Iwakiri, Hirotomo; Yoshida, Naoaki; Okuno, Kenji

    2007-08-01

    Deuterium retention behavior in highly oriented pyrolytic graphite (HOPG), poly-crystalline diamond, poly-crystalline SiC, sintered WC, and converted B 4C were investigated to reveal tritium behavior in re-deposition and co-deposition layers. Such layers would contain carbon, when the first wall and/or divertor were made of graphite or carbon-containing materials. Furthermore, the employment of other materials such as tungsten, and first wall conditioning such as boronization would complicate the layers. No different deuterium trapping sites due to carbon from those in HOPG were found in all the samples, where two deuterium trapping processes were observed: hot atom chemical trapping of energetic deuterium by a dangling bond of carbon and thermochemical trapping of thermalized deuterium in a constituent atom vacancy surrounded by carbons. Additionally, the latter reaction could be easily counteracted by or competed with the other deuterium trapping reactions by constituent atoms.

  1. Microstructural studies of hydrogen and deuterium in bcc refractory metals

    SciTech Connect

    Moss, S.C.

    1980-01-01

    Over the past four years this research has been principally concerned with uncovering the microstructural atomic arrangements in alloys of hydrogen and deuterium with bcc refractory metals. Because these are interstitial phases in which the host metal lattice is substantially deformed by the incorporation of the H(D) atoms, there are pronounced x-ray scattering effects. X-ray diffraction has, therefore, been the main structural tool. A main objective of the project has been to determine the degree to which phase relations and solid solution properties in metal-hydride alloys depend upon the hydrogen-hydrogen interaction via the displacement field of the metal atoms. This has often included the elucidation of subtle thermodynamic properties which are revealed in structural studies.

  2. The Vapor Pressures and Derived Thermal Properties of Hydrogen and Deuterium

    Microsoft Academic Search

    R. B. Scott; F. G. Brickwedde; Harold C. Urey; M. H. Wahl

    1934-01-01

    (1) The vapor pressure equations of liquid and solid, normal deuterium were determined by comparison of the vapor pressure of deuterium with that of liquid, normal hydrogen between 13.9° and 20.40°K. The triple and boiling points of deuterium were found to be 18.58° and 23.5°K, respectively. (2) The changes with time in the vapor pressures of liquid hydrogen and liquid

  3. Diffusion of hydrogen, deuterium, and tritium in niobium

    SciTech Connect

    Matusiewicz, Gerald Robert

    1981-01-01

    The diffusion of hydrogen in niobium was investigated over the temperature range 148 to 500 degrees Kelvin, using measurements of the elastic after effect caused by long range diffusion (the Gorsky Effect). Relaxation curves for pure annealed niobium were generally not of the single exponential form expected from the Gorsky Effect theory, but were described well by a sum of two exponential curves with different amplitudes and relaxation times. The effects of oxygen and nitrogen interstitials on the diffusion were studied and were not in agreement with conventional trapping models. Deuterium and tritium diffusion in niobium were also studied, and a non-classical isotope effect was observed. Hydrogen diffusion coefficients in several Nb-Ta alloys were measured, and the diffusivity in all these alloys exhibited a non-Arrhenius temperature dependence. Experimental results were compared to several models for diffusion and trapping. A model is presented which can account for the form of the relaxation curves observed in pure, annealed niobium.

  4. Infrared spectroscopy of solid hydrogen sulfide and deuterium sulfide.

    PubMed

    Fathe, Kristin; Holt, Jennifer S; Oxley, Susan P; Pursell, Christopher J

    2006-09-21

    The infrared spectra of solid hydrogen sulfide (H2S) and deuterium sulfide (D2S) were collected at very low temperatures. Vapor deposition of thin films at the lowest temperature of 10 K produced amorphous solids while deposition at 70 K yielded the crystalline phase III. Infrared interference fringe patterns produced by the films during deposition were used to determine the film thickness. Careful measurement of the integrated absorbance peaks, along with the film thickness, allowed determination of the integrated band intensities. This report represents the first complete presentation of the infrared spectra of the amorphous solids. Observations of peaks near 3.915 and 1.982 microm (ca. 2554 and 5045 cm(-1), respectively) may be helpful in the conclusive identification of solid hydrogen sulfide on the surface of Io, a moon of Jupiter. PMID:16970373

  5. Hydrogen and deuterium in the local interstellar medium

    SciTech Connect

    Murthy, J.N.

    1987-01-01

    This work reports on the results of a series of IUE observations of interstellar HI and DI Ly..cap alpha.. absorption against the chromospheric Ly..cap alpha.. emission of the nearby late-type stars ..cap alpha.. Cen B(1.3 pc), epsilon Eri (3.3 pc), Procyon (3.5 pc), Altair (5.1 pc), Capella (13.2 pc), and HR 1099 (33 pc). The density, velocity dispersion, and bulk velocity of the neutral hydrogen along the line of sight to each of these stars was derived. Lower limits were placed on the deuterium-to-hydrogen (D/H) ratio towards the same stars. These IUE results are generally consistent with previous observations of the same stars with the Copernicus satellite showing that this modeling procedure is independent of stellar variations over a period of several years. The HI absorption profile towards Altair shows a broad saturated core and steep line wings, consistent with a multicomponent interstellar medium in that direction. The bulk velocities towards the other stars are consistent with a bulk flow from the approximate direction of the galactic center but do show local variations from a uniform flow, possibly indicating a complicated velocity structure even in the solar neighborhood. Interstellar deuterium is detected towards every star except Altair and the derived values for the D/H ratio are consistent with those previously found with Copernicus.

  6. Electron scattering experiments with polarized hydrogen/deuterium internal targets

    NASA Astrophysics Data System (ADS)

    van Buuren, L. D.

    2000-06-01

    A high-density polarized hydrogen/deuterium internal gas target is presented. The target is based on a setup previously used in electron scattering experiments with tensor-polarized deuterium [1]. To increase the target thickness, new state-of-the-art permanent sextupole magnets and a more powerful pumping system were installed together with a longer (60 cm) and colder (˜70 K) cylindrical storage cell. Electro-nuclear spin observables were measured by scattering longitudinally polarized electrons stored in the AmPS ring (NIKHEF) from the target gas. The product of electron beam and target polarization was determined from the known e'p (quasi) elastic asymmetries. We achieved a target thickness of 1.1×1014atoms/cm2 which with typical beam currents of 110 mA corresponds to a luminosity of about 7.5×1031cm-2 s-1. Target and beam polarizations up to 0.7 and 0.65 respectively were obtained.

  7. Toward standardizing deuterium content reporting in hydrogen exchange-MS.

    PubMed

    Sheff, Joey G; Schriemer, David C

    2014-12-16

    We introduce a method to monitor dispensing ratios during labeling reactions in hydrogen exchange (HX)-MS. The method corrects for systematic and random dispensing errors and harmonizes data incorporating variable %D2O in the experiment design. A correction factor for deuterium levels is obtained by quantifying the relative signal intensities arising from nonexchanging heavy caffeine (spiked into labeling buffer) and light caffeine (spiked into sample solutions). Dispensing variability over a wide range of %D2O composition can be detected and corrected to a common value, and although random dispensing error is usually minor, we show it can be the limiting factor in high quality signal measurements. Applying a dispensing control is therefore an effective tool for monitoring measurement precision in HX-MS. PMID:25427063

  8. Possible Coexistence of Antihydrogen with Hydrogen, Deuterium and Tritium Atoms

    E-print Network

    Abdel-Raouf, Mohamed Assad

    2007-01-01

    Recent productions of large numbers of cold antiprotons as well as the formation of antihydrogens at CERN and Fermilab have raised basic questions about possible coexistence of matter and antimatter in nature. In the present work, previous mathematical considerations are revisited which support the possible coexistence of Antihydrogen with Hydrogen, Deuterium and Tritium atoms. In particular, the main objective of the present work is to present computational treatments which confirm the possible formation of these quasi molecules in laboratory. These treatments are based on a nonadiabatic picture of the system in which generalized basis functions are adjusted within the framework of Rayleigh-Ritz' variational method. Thus, the Born-Oppenheimer adiabatic picture of the system, which implies the formation of exotic molecules composed explicitly of fixed quasi heavy atoms (containing at least two leptons, e.g. protonium) and quasi light atoms (e.g. positronium), is ruled out in the present work. In other words, ...

  9. Diffusion of hydrogen, deuterium, and tritium in niobium

    SciTech Connect

    Matusiewicz, G.R.

    1981-01-01

    The diffusion of hydrogen in niobium was investigated over the temperature range 148 to 500 degrees Kelvin, using measurements of the elastic after effect caused by long range diffusion (the Gorsky Effect). Relaxation curves for pure annealed niobium were generally not of the single exponential form expected from the Gorsky Effect theory, but were described well by a sum of two exponential curves with different amplitudes and relaxation times. Relaxation curves for pure niobium that had been cold worked had the expected form, but the hydrogen diffusion deviated from an Arrhenius temperature dependence. The effects of oxygen and nitrogen interstitials on the diffusion were studied and were not in agreement with conventional trapping models. Deuterium and tritium diffusion in niobium were also studied, and a non-classical isotope effect was observed. Hydrogen diffusion coefficients in several Nb-Ta alloys were measured, and the diffusivity in all these alloys exhibited a non-Arrhenius temperature dependence. Experimental results were compared to several models for diffusion and trapping. A model is presented which can account for the form of the relaxation curves observed in pure, annealed nioium.

  10. Thermotransport of hydrogen and deuterium in vanadium, niobium and tantalum alloys

    SciTech Connect

    Smith, M.F.

    1981-10-01

    Heats of transport have been determined for thermotransport of hydrogen and deuterium in pure vanadium, niobium and tantalum; in vanadium alloyed with either niobium, titanium or chromium; and in niobium-tantalum alloys. In all cases, thermotransport was toward colder regions and was significantly greater for deuterium than for hydrogen. A mass spectrometric technique was used to simultaneously measure heats of transport for hydrogen and deuterium in a single specimen containing both isotopes. This technique greatly increased the precision with which isotope effects in the heat of transport could be measured. The predominant effect of alloying was to dramatically increase thermotransport; however, thermotransport decreased as niobium was added to tantalum.

  11. Counter-Permeation of Deuterium and Hydrogen Through INCONEL 600[reg

    SciTech Connect

    Takeda, Tetsuaki [Japan Atomic Energy Research Institute (Japan); Iwatsuki, Jin [Ishikawajima-Harima Heavy Industries Company, Limited (Japan)

    2004-04-15

    Permeation of hydrogen isotopes through a high-temperature alloy used for heat exchanger and catalyst pipes is an important problem in the hydrogen production system connected to the High-Temperature Engineering Test Reactor (HTTR). The objective of this study is to investigate the effect of the existence of hydrogen in an outside pipe on the amount of permeated deuterium through the pipe. It was found that the amount of permeated deuterium decreases by increasing the partial pressure of hydrogen in the outside pipe when the partial pressure of deuterium in the pipe is lower than 100 Pa and that of hydrogen in the outside pipe is larger than 10 kPa. The amount of permeated deuterium on counter permeation was predicted quantitatively by using an effectiveness factor for diffusivity of deuterium in metals and by taking into account the equilibrium state for hydrogen, deuterium, and HD molecules on the metal surface. From the results obtained in this study, it is supposed that the amount of tritium transferred from the primary circuit of the HTTR to the hydrogen production system will be reduced by the existence of high-pressure hydrogen in the catalyst pipe of the steam reformer.

  12. Hydrogen-Deuterium Exchange of Meteoritic Dicarboxylic Acids During Aqueous Extraction

    NASA Technical Reports Server (NTRS)

    Fuller, M.; Huang, Y.

    2002-01-01

    This study examines the extent of hydrogen-deuterium exchange on dicarboxylic acids during aqueous extraction. Deuterium enrichment was observed to be a function of diacid structure as well as delta-D. Additional information is contained in the original extended abstract.

  13. Measuring Deuterium Enrichment of Glucose Hydrogen Atoms by Gas Chromatography/Mass Spectrometry

    E-print Network

    Antoniewicz, Maciek R.

    We developed a simple and accurate method for determining deuterium enrichment of glucose hydrogen atoms by electron impact gas chromatography mass spectrometry (GC/MS). First, we prepared 18 derivatives of glucose and ...

  14. Recombination-induced athermal migration of hydrogen and deuterium in SiC

    NASA Astrophysics Data System (ADS)

    Koshka, Yaroslav; Krishnan, Bharat

    2005-02-01

    The phenomenon of recombination-induced formation of hydrogen-defect complexes in epitaxial silicon carbide (SiC) was further investigated on p-type samples treated in deuterium plasma. Qualitatively similar effects were observed for hydrogen and deuterium. The formation of hydrogen-related (deuterium-related) defects would depend on the temperature of the sample during plasma treatment, with lower process temperatures causing only incorporation of hydrogen (deuterium) near the surface without any significant formation of electrically or optically active hydrogen-related or deuterium-related defects in the epilayer. Higher process temperatures normally produced more efficient formation of new centers, including passivation of acceptors in SiC. In all cases, prolonged excitation of the hydrogenated (deuterated) samples with above-bandgap light at reduced temperatures caused recombination-induced formation of a few different defect centers. A confirmation of the long-range athermal migration of hydrogen from the surface into the bulk of the sample was obtained. It has been established that it is the recombination-induced migration of hydrogen that is responsible for the formation of hydrogen-related defect centers under optical excitation.

  15. Comparison of deuterium and hydrogen experiments in the Sustained Spheromak Physics Experiment

    Microsoft Academic Search

    R. D. Wood; D. N. Hill; E. B. Hooper; H. S. McLean; D. Ryutov; S. Woodruff

    2005-01-01

    In this paper we report on the results of deuterium and hydrogen experiments in the Sustained Spheromak Physics Experiment (SSPX). We have compared ?500 deuterium discharges with similar discharges in hydrogen. Typically, we produce H2 plasmas with peak toroidal currents in the range of 0.6MA, electron temperatures (Te) of ?200eV and energy confinement times (?E) of ?200?s. The D2 fueled

  16. Recombinant Nepenthesin II for Hydrogen/Deuterium Exchange Mass Spectrometry.

    PubMed

    Yang, Menglin; Hoeppner, Morgan; Rey, Martial; Kadek, Alan; Man, Petr; Schriemer, David C

    2015-07-01

    The pitcher secretions of the Nepenthes genus of carnivorous plants contain a proteolytic activity that is very useful for hydrogen/deuterium exchange mass spectrometry (HX-MS). Our efforts to reconstitute pitcher fluid activity using recombinant nepenthesin I (one of two known aspartic proteases in the fluid) revealed a partial cleavage profile and reduced enzymatic stability in certain HX-MS applications. We produced and characterized recombinant nepenthesin II to determine if it complemented nepenthesin I in HX-MS applications. Nepenthesin II shares many properties with nepenthesin I, such as fast digestion at reduced temperature and pH, and broad cleavage specificity, but in addition, it cleaves C-terminal to tryptophan. Neither enzyme reproduces the C-terminal proline cleavage we observed in the natural extract. Nepenthesin II is considerably more resistant to chemical denaturants and reducing agents than nepenthesin I, and it possesses a stability profile that is similar to that of pepsin. Higher stability combined with the slightly broader cleavage specificity makes nepenthesin II a useful alternative to pepsin and a more complete replacement for pitcher fluid in HX-MS applications. PMID:25993527

  17. Carbon-13 and deuterium isotope effects on oxalacetate decarboxylation by pyruvate carboxylase

    SciTech Connect

    Attwood, P.V.; Tipton, P.A.; Cleland, W.W.

    1986-12-16

    Deuterium and /sup 13/C isotope effects for the enzymic decarboxylation of oxalacetate showed that both deuterium- and /sup 13/C-sensitive steps in the reaction are partially rate limiting. A normal alpha-secondary effect of 1.2 per deuterium was calculated for the reaction in which pyruvate-d3 was the substrate, suggesting that the enolate of pyruvate was an intermediate in the reaction. The large normal alpha-secondary deuterium isotope effect of 1.7 when oxalacetate-d2 was the substrate suggests that the motions of the secondary hydrogens are coupled to that of the primary hydrogen during the protonation of the enolate of pyruvate. The reduction in the magnitude of the /sup 13/C isotope effect for the oxamate-dependent decarboxylation of oxalacetate from 1.0238 to 1.0155 when the reaction was performed in D/sub 2/O (primary deuterum isotope effect = 2.1) clearly indicates that the transfer of the proton and carboxyl group between biotin and pyruvate does not occur via a single concerted reaction. Mechanisms in which biotin is activated to react with CO/sub 2/ (prior to transfer of the proton on N-1) by bond formation between the sulfur and the ureido carbon, or in which the sequence of events is decarboxylation of oxalacetate, proton transfer from biotin to enolpyruvate, and carboxylation of enolbiotin, predict that the /sup 13/C isotope effect in D/sub 2/O should be substantially lower than the observed value. A stepwise mechanism that does fit the data is one in which a proton is removed from biotin by a sulfhydryl group on the enzyme prior to carboxyl transfer, as long as the sulfhydryl group has an abnormally low pK.

  18. Hydrogen/deuterium isotope effects in water and aqueous solutions of organic molecules and proteins

    NASA Astrophysics Data System (ADS)

    Price, David L.; Fu, Ling; Bermejo, F. Javier; Fernandez-Alonso, Felix; Saboungi, Marie-Louise

    2013-10-01

    It is pointed out that hydrogen/deuterium substitution, frequently used in neutron scattering studies of the structure and dynamics of hydrogenous samples, can have significant effects on structure, phase behavior and protein stability. The effects must be kept in mind in the interpretation of such experiments. In suitable cases, these effects can be mitigated by an appropriate choice of experimental conditions.

  19. The deuterium/proton ratio as a measure of anomalous hydrogen

    NASA Astrophysics Data System (ADS)

    Lopate, C.

    The degree to which anomalous hydrogen exists in cosmic rays may have a profound effect on structures in the heliosphere, such as the termination shock. Since the source of the anomalous component is believed to be neutral gas in the local interstellar medium (LISM) and since there is little neutral deuterium in the LISM, the deuterium/proton ratio provides information about the fraction of observed hydrogen which could be anomalous. The Pioneer 10 data have been reanalyzed with an improved galactic deuterium spectrum. This report includes all the Pioneer 10 deuterium data from the University of Chicago instrument. Our results agree with recent reports that anomalous hydrogen is a significant component to the total hydrogen measurements in the outer heliosphere. These new results suggest that the anomalous hydrogen comprised about 60% during the solar minimum of 1987 and about 45% during the 1978 solar minimum, of the hydrogen flux near 70 MeV. The anomalous hydrogen disappeared by 1991, reappeared at Pioneer 10 near 64 AU in 1995, and persisted strongly since then.

  20. Measurement of the nuclear polarization of hydrogen and deuterium molecules using a Lamb-shift polarimeter

    SciTech Connect

    Engels, Ralf, E-mail: r.w.engels@fz-juelich.de; Gorski, Robert; Grigoryev, Kiril; Mikirtychyants, Maxim; Rathmann, Frank; Seyfarth, Hellmut; Ströher, Hans; Weiss, Philipp [Institut für Kernphysik, Forschungszentrum Jülich, Wilhelm-Johnen-Str. 1, 52428 Jülich (Germany); Kochenda, Leonid; Kravtsov, Peter; Trofimov, Viktor; Tschernov, Nikolay; Vasilyev, Alexander; Vznuzdaev, Marat [Laboratory of Cryogenic and Superconductive Technique, Petersburg Nuclear Physics Institute, Orlova Roscha 1, 188300 Gatchina (Russian Federation); Schieck, Hans Paetz gen. [Institut für Kernphysik, Universität zu Köln, Zülpicher Str. 77, 50937 Köln (Germany)

    2014-10-15

    Lamb-shift polarimeters are used to measure the nuclear polarization of protons and deuterons at energies of a few keV. In combination with an ionizer, the polarization of hydrogen and deuterium atoms was determined after taking into account the loss of polarization during the ionization process. The present work shows that the nuclear polarization of hydrogen or deuterium molecules can be measured as well, by ionizing the molecules and injecting the H{sub 2}{sup +} (or D{sub 2}{sup +}) ions into the Lamb-shift polarimeter.

  1. Longitudinal-Transverse Separations of Structure Functions at Low $Q^2$ for Hydrogen and Deuterium

    SciTech Connect

    V. Tvaskis; M. E. Christy; J. Arrington; R. Asaturyan; O. K. Baker; H. P. Blok; P. Bosted; M. Boswell; A. Bruell; A. Cochran; L. Cole; J. Crowder; J. Dunne; R. Ent; H. C. Fenker; B. W. Filippone; K. Garrow; A. Gasparian; J. Gomez; H.E. Jackson; C. E. Keppel; E. Kinney; Y. Liang; W. Lorenzon; A. Lung; D. J. Mack; J. W. Martin; K. McIlhany; D. Meekins; R. G. Milner; J. H. Mitchell; H. Mkrtchyan; B. Moreland; V. Nazaryan; I. Niculescu; A. Opper; R. B. Piercey; D.H. Potterveld; B. Rose; Y. Sato; W. Seo; G. Smith; K. Spurlock; G. van der Steenhoven; S. Stepanyan; V. Tadevosian; A. Uzzle; W. F. Vulcan; S. A. Wood; B. Zihlmann; V. Ziskin

    2006-11-20

    We report on a study of the longitudinal to transverse cross section ratio, R={sigma}{sub L} {sigma}{sub T}, at low values of x and Q{sup 2}, as determined from inclusive inelastic electron-hydrogen and electron-deuterium scattering data from Jefferson Lab Hall C spanning the four-momentum transfer range 0.06 < Q{sup 2} < 2.8 GeV{sup 2}. Even at the lowest values of Q{sup 2}, R remains nearly constant and does not disappear with decreasing Q{sup 2}, as expected. We find a nearly identical behavior for hydrogen and deuterium.

  2. Fractionation of hydrogen and deuterium on Venus due to collisional ejection

    NASA Astrophysics Data System (ADS)

    Gurwell, M. A.; Yung, Y. L.

    1993-02-01

    The collisional ejection process for hydrogen on Venus is reanalyzed. Improved values for the efficiency of H and D escape as a function of the ionospheric temperature are reported. It is proposed that the reduction of the hydrogen flux for collisional ejection be reduced from 8 to 3.5 x 10 exp 6/sq cm/s, and a revised D/H fractional factor of 0.47 due to collisional ejection is suggested. The resulting deuterium flux is 3.1 x 10 exp 4/sq cm/s, roughly six times the flux due to charge exchange, making collisional ejection the dominant escape mechanism for deuterium on Venus.

  3. Longitudinal Lelectroproduction of Charged Pions on Hydrogen, Deuterium, and Helium 3

    SciTech Connect

    David Gaskell

    2001-05-01

    Conventional pictures of nuclear interactions, in which the pion mediates the long/medium range part of the nuclear force, predict an enhancement of the virtual pion cloud in nuclei relative to that in the free nucleon. Jefferson Lab Experiment E91003 measured charged pion electroproduction from Hydrogen, Deuterium, and Helium-3. The longitudinal cross section, which in the limit of pole dominance can be viewed as the quasifree knockout of a virtual pion, was extracted via a Rosenbluth separation. The longitudinal cross sections from Deuterium and Helium-3 were compared to Hydrogen to look for signatures of the nuclear pions.

  4. The ground state properties of spin-aligned atomic hydrogen, deuterium, and tritium

    NASA Technical Reports Server (NTRS)

    Etters, R. D.; Dugan, J. V., Jr.; Palmer, R. W.

    1975-01-01

    The internal energy, pressure, and compressibility of ground-state, spin-aligned atomic hydrogen, deuterium, and tritium are calculated assuming that all pair interactions occur via the atomic triplet (spin-aligned) potential. The conditions required to obtain atomic hydrogen and its isotopes in bulk are discussed; such a development would be of value in propulsion systems because of the light mass and energetic recombination of atomic hydrogen. Results show that atomic triplet hydrogen and deuterium remain gaseous at 0 K, and that tritium forms a liquid with a binding energy of approximately -0.75 K per atom at a molar volume of 130 cu cm per mole. The pair distribution function for these systems is calculated, and the predicted superfluid behavior of atomic triplet hydrogen and tritium is briefly discussed.

  5. Laser separation of hydrogen isotopes: Tritium-from-deuterium recovery

    SciTech Connect

    Magnotta, F.; Herman, I.P.; Aldridge, F.T.; Maienschein, J.L.

    1984-02-01

    Single-step enrichment factors exceeding 15,000 have been observed in the removal of tritium-from-deuterium by 12 ..mu..m laser multiple-photon dissociation of chloroform. The photochemistry and photophysics of this process is discussed along with prospects for implementation of this method in practical heavy water reactor detritiation. 7 refs., 7 figs., 1 tab.

  6. Online hydrogen/deuterium exchange performed in the ion mobility cell of a hybrid mass spectrometer.

    PubMed

    Nagy, Kornél; Redeuil, Karine; Rezzi, Serge

    2009-11-15

    The present paper describes the performance of online, gas-phase hydrogen/deuterium exchange implemented in the ion mobility cell of a quadrupole time-of-flight mass spectrometer. Deuterium oxide and deuterated methanol were utilized to create deuterated vapor that is introduced into the ion mobility region of the mass spectrometer. Hydrogen/deuterium exchange occurs spontaneously in the milliseconds time frame without the need of switching the instrument into ion mobility mode. The exchange was studied in case of low molecular weight molecules and proteins. The observed number of exchanged hydrogens was equal to the number of theoretically exchangeable hydrogens for all low molecular weight compounds. This method needs only minimal instrumental modifications, is simple, cheap, environment friendly, compatible with ultraperformance liquid chromatography, and can be implemented on commercially available instruments. It does not compromise choice of liquid chromatographic solvents and accurate mass or parallel-fragmentation (MS(E)) methods. The performance of this method was compared to that of conventional alternatives where the deuterated solvent is introduced into the cone gas of the instrument. Although the degree of exchange was similar between the two methods, the "cone gas method" requires 10 times higher deuterated solvent volumes (50 muL/min) and offers reduced sensitivity in the tandem mass spectrometry (MS/MS) mode. The presented method is suggested as a standard future element of mass spectrometers to aid online structural characterization of unknowns and to study conformational changes of proteins with hydrogen/deuterium exchange. PMID:19848411

  7. Deuterium accumulation in carbon materials at high fluence

    NASA Astrophysics Data System (ADS)

    Pisarev, A.; Tanabe, T.; Emmoth, B.; Trifonov, N.; Rusinov, A.; Stepanov, S.; Gasparyan, Yu.; Spitsyn, A.; Khripunov, B.

    2009-06-01

    D retention in fine grain graphite MPG-8 and carbon fiber composite NB31 after exposure to plasma was investigated by means of thermal desorption spectroscopy. It was observed, that deuterium accumulation in the two materials was similar in the region of the fluence of 10 22-4 × 10 24 D +/m 2, though NB31 retains about twice as much. The retention in MPG-8 reveals no saturation at high fluences and no flux dependence in the range of (0.5-3.5) × 10 20 D +/m 2 s. The difference between polished and unpolished samples, as well as between samples kept in air for various times after irradiation was within the experimental uncertainty.

  8. Isomeric Differentiation of Green Tea Catechins using Gas-Phase Hydrogen/Deuterium Exchange Reactions

    PubMed Central

    Niemeyer, Emily D.; Brodbelt, Jennifer S.

    2007-01-01

    Hydrogen/deuterium exchange reactions in a quadrupole ion trap mass spectrometer are used to differentiate galloylated catechin stereoisomers (catechin gallate and epicatechin gallate; gallocatechin gallate and epigallocatechin gallate) and the non-galloylated analogs (catechin and epicatechin, gallocatechin and epigallocatechin). Significant differences in the hydrogen/deuterium exchange behavior of the four pairs of deprotonated catechin stereoisomers are observed upon reaction with D2O. Interestingly, the non-galloylated catechins undergo H/D exchange to a much greater extent than the galloylated species, incorporating deuterium at both aromatic/allylic and active phenolic sites. Non-galloylated catechin isomers are virtually indistinguishable by their H/D exchange kinetics over a wide range of reaction times (0.05 to 10 s). Our experimental results are explained using high-level ab initio calculations to elucidate the subtle structural variations in the catechin stereoisomers that lead to their differing H/D exchange kinetics. PMID:17702600

  9. Diffusion of hydrogen and deuterium on the (110) plane of tungsten

    Microsoft Academic Search

    R. Difoggio; R. Gomer

    1982-01-01

    The diffusion of hydrogen and deuterium and of mixtures of these isotopes on the (110) plane of tungsten has been studied by the field-emission-fluctuation method as a function of coverage theta and T It was possible to show that the results in this system are not influenced by the applied field required for emission. Thermally activated diffusion was found for

  10. OLIGOSACCHARIDE STRUCTURES STUDIED BY HYDROGEN-DEUTERIUM EXCHANGE (HX) AND MALDI-TOF MASS SPECTROMETRY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hydrogen-deuterium exchange matrix-assisted laser desorption/ionization - time-of-flight mass spectrometry (HX-MALDI-TOF MS) is reported for the first time for the determination of exchangeable protons in diverse oligosaccharide and glycoconjugate structures. The method is generally analogous to th...

  11. Hydrogen fluoride and deuterium fluoride lasers. Citations from the International Aerospace Abstracts data base

    NASA Technical Reports Server (NTRS)

    Mauk, S. C.

    1980-01-01

    Research cited from the international literature adresses various aspects of hydrogen fluoride and deuterium fluoride lasers. Topics covered include flows, laser outputs, molecular relaxation, molecular rotation, energy conversion efficiency, reaction kinetics, and laser materials. Continous wave and pulsed laser are considered. This updated bibliography contains 283 citations, 53 of which are new additions to the previous edition.

  12. Helium-3 Generation from the Interaction of Deuterium Plasma inside a Hydrogenated Lattice: Red Fusion

    NASA Astrophysics Data System (ADS)

    Leal-Quiros, Edbertho; Leal-Escalante, David A.

    2015-03-01

    Helium-3 has been created in a nuclear fusion reaction by fusing deuterium ions from deuterium plasma with hydrogen ions in a “RED” (the Spanish word for net) or crystal lattice, a method we called red fusion ("Fusion en la red cristalina"), because is a new method to make nuclear fusion reaction. In this paper, it will be show the experimental results where the helium-3 has been generated for the first time in this kind of new method to confine deuterium and hydrogen inside the RED or lattice of the hydrogenated crystal and that confinement inside the RED facilitated overcoming the Coulomb barrier between them and helium-3 and phonons are produced in this fusion reaction. The results of a long time research in which helium-3, has been created in a fusion reaction inside the lattice or RED of the crystal that contained hydrogen after adequate interaction of deuterium plasma at appropriate high temperature and magnetic confinement of the Mirror/Cusp Plasma Machine at Polytechnic University of Puerto Rico, designed by the authors. Several mass spectra and visible light spectrum where the presence of helium-3 was detected are shown. The experiment was repeated more than 200 times showing always the generation of helium-3. In this experiment no gamma rays were detected. For this experiment several diagnostic instruments were used. The data collection with these control instrumentation are shown. Thus, it is an important new way to generate Helium-3. © 2013 NEOPOWERTECH, LLC. All rights reserved.

  13. Dual Studies on a Hydrogen-Deuterium Exchange of Resorcinol and the Subsequent Kinetic Isotope Effect

    ERIC Educational Resources Information Center

    Giles, Richard; Kim, Iris; Chao, Weyjuin Eric; Moore, Jennifer; Jung, Kyung Woon

    2014-01-01

    An efficient laboratory experiment has been developed for undergraduate students to conduct hydrogen-deuterium (H-D) exchange of resorcinol by electrophilic aromatic substitution using D[subscript 2]O and a catalytic amount of H[subscript 2]SO[subscript 4]. The resulting labeled product is characterized by [superscript 1]H NMR. Students also…

  14. Permeation and diffusion of hydrogen and deuterium under fission-reactor radiation

    NASA Astrophysics Data System (ADS)

    Schwarzinger, G. W.; Dobrozemsky, R.

    1984-05-01

    Diffusion- and solubility-data of hydrogen and deuterium in steel samples at 520 K were measured in the primary radiation environment of the ASTRA-reactor (lightwater moderated 8 MW research reactor) by means of a new-developed irradiation capsule. The method is based on gas-content measurements in small samples before and after irradiation. First results are reported.

  15. Hydrogen and deuterium internal friction behavior in vanadium-niobium alloys

    SciTech Connect

    Kim, Seon Jin

    1988-07-01

    Internal friction behavior of hydrogen in vanadium-niobium alloys containing from 40 at. pct. niobium to 100 at. pct. niobium as a function of hydrogen concentrations was investigated. The internal friction measurements were performed in an electrostatic drive and detection apparatus for rods in flexural vibration in the temperature range from 30/degree/K to 290/degree/K. An internal friction peak due to hydrogen was found in all the vanadium-niobium alloys. The peak was considered to be due to the jumps of hydrogen atoms in solid solution. The peak moved toward lower temperatures with increasing hydrogen concentration. In other words, the activation energies of the hydrogen motion responsible for the internal friction peaks decreased with increasing hydrogen concentration. The activation energies and /tau//sub 0/ values for the hydrogen internal friction processes obtained from the present study were compared to those obtained from long range diffusion experiments. In order to examine the isotope effect, internal friction of deuterium in the same alloys were measured and compared to those of hydrogen. Effects of oxygen on the internal friction behavior of hydrogen and deuterium were also investigated. 45 refs., 23 figs., 9 tabs.

  16. Solubility of hydrogen and deuterium in body-centered-cubic uranium alloys

    Microsoft Academic Search

    G. L. Powell

    1979-01-01

    The equilibrium constants for the reaction of several body-centered-cubic uranium-molybdenum alloys, uranium-niobium alloys, and a uranium-niobium-zirconium alloy with both hydrogen gas and deuterium gas have been determined with a precision of 1% at infinite dilution as a function of temperature. The free-energy function for hydrogen in these alloys has been determined and expressed in terms of the bound-proton model. Analytical

  17. In-ESI source hydrogen/deuterium exchange of carbohydrate ions.

    PubMed

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

    2014-03-01

    We present the investigation of hydrogen/deuterium (H/D) exchange of carbohydrates ions occurring in the electrospray ion source. The shape of the deuterium distribution was observed to be considerably dependent on the temperature of the ion transfer tube and the solvent used. If deuterated alcohol (EtOD or MeOD) or D2O/deuterated alcohol is used as an electrospray solvent, then for high temperatures (>350 °C), intensive back exchange is observed, resulting in ?30% depth of the deuterium exchange. At low temperatures (<150 °C), the back exchange is weaker and the depth of the deuterium exchange is ?70%. In the intermediate temperature region (?250 °C), the deuterium distribution is unusually wide for methanol and bimodal for ethanol. The addition of 1% formic acid results in low (?30%) depth of the deuterium exchange for any temperature in the operating region. The bimodal distribution for the ethanol can be possibly explained by the presence of differently folded gas-phase ions of carbohydrates. PMID:24499243

  18. Definitive proof of graphene hydrogenation by Clemmensen reduction: use of deuterium labeling

    NASA Astrophysics Data System (ADS)

    Sofer, Zden?k; Jankovský, Ond?ej; Libánská, Alena; Šimek, Petr; Nová?ek, Michal; Sedmidubský, David; Macková, Anna; Mikšová, Romana; Pumera, Martin

    2015-06-01

    Graphane is one of the most intensively studied derivatives of graphene. Here we demonstrate the evaluation of exact degree of graphene hydrogenation using the Clemmensen reduction reaction and deuterium labeling. The Clemmensen reduction reaction is based on application of zinc in an acid environment. It effectively reduces various functional groups (like ketones) present in graphite oxide. However, the mechanism of reduction is still unknown and elusive. Here we bring a major insight into the mechanisms of the Clemmensen reduction via deuterium labeling and the topochemical approach applied on graphite oxide. The use of deuterated reactants and the exact measurement of deuterium concentration in reduced/hydrogenated graphene by nuclear methods can be used for accurate estimation of C-H bond abundance in graphene. Various topochemical configurations of experiments showed that the reduction of a ketonic group proceeds in contact with the zinc metal by a carbenoid mechanism. Our results showed that the application of nuclear methods of isotope analysis in combination with deuterium labeling represents a very effective tool for investigation of graphene based materials. Our results demonstrate that graphene based materials can also be effectively used for the investigation of organic reaction mechanisms, because the robust structure of graphene allows the use of various spectroscopic techniques which could not be applied on small organic molecules.Graphane is one of the most intensively studied derivatives of graphene. Here we demonstrate the evaluation of exact degree of graphene hydrogenation using the Clemmensen reduction reaction and deuterium labeling. The Clemmensen reduction reaction is based on application of zinc in an acid environment. It effectively reduces various functional groups (like ketones) present in graphite oxide. However, the mechanism of reduction is still unknown and elusive. Here we bring a major insight into the mechanisms of the Clemmensen reduction via deuterium labeling and the topochemical approach applied on graphite oxide. The use of deuterated reactants and the exact measurement of deuterium concentration in reduced/hydrogenated graphene by nuclear methods can be used for accurate estimation of C-H bond abundance in graphene. Various topochemical configurations of experiments showed that the reduction of a ketonic group proceeds in contact with the zinc metal by a carbenoid mechanism. Our results showed that the application of nuclear methods of isotope analysis in combination with deuterium labeling represents a very effective tool for investigation of graphene based materials. Our results demonstrate that graphene based materials can also be effectively used for the investigation of organic reaction mechanisms, because the robust structure of graphene allows the use of various spectroscopic techniques which could not be applied on small organic molecules. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr01356a

  19. Quantum interference effects in laser spectroscopy of muonic hydrogen, deuterium and helium-3

    E-print Network

    Amaro, Pedro; Krauth, Julian J; Diepold, Marc; Fratini, Filippo; Safari, Laleh; Machado, Jorge; Antognini, Aldo; Kottmann, Franz; Indelicato, Paul; Pohl, Randolf; Santos, José Paulo

    2015-01-01

    Quantum interference between energetically close states is theoretically investigated, with the state structure being observed via laser spectroscopy. In this work, we focus on hyperfine states of selected hydrogenic muonic isotopes, and on how quantum interference affects the measured Lamb shift. The process of photon excitation and subsequent photon decay is implemented within the framework of non-relativistic second-order perturbation theory. Due to its experimental interest, detailed calculations are performed for muonic hydrogen, deuterium and helium-3. We restrict our analysis to the case of photon scattering by incident linear polarized photons and the polarization of the scattered photons not being observed, which is the frequent case in most of laser spectroscopy experiments, e.g. the ones of the CREMA collaboration. We conclude that while quantum interference effects can be safely neglected in muonic hydrogen and helium-3, in case of muonic deuterium there are resonances with close proximity, where ...

  20. Carbon and hydrogen isotopic compositions of New Zealand geothermal gases

    NASA Astrophysics Data System (ADS)

    Lyon, G. L.; Hulston, J. R.

    1984-06-01

    Carbon and hydrogen isotopic compositions are reported for methane, hydrogen and carbon dioxide from four New Zealand geothermal areas: Ngawha, Wairakei, Broadlands and Tikitere. Carbon-13 contents are between -24.4 and -29.5%. (PDB) for methane, and between -3.2 and -9.1%. for carbon dioxide. Deuterium contents are between -142 and -197%. (SMOW) for methane and between -310 and -600%. for hydrogen. The different areas have different isotopic compositions with some general relationships to reservoir temperature. The isotopic exchange of hydrogen with water indicates acceptable reservoir temperatures of 180-260°C from most spring samples but often higher than measured temperatures in well samples. Indicated temperatures assuming 13C equilibria between CH 4 and CO 2 are 100-200°C higher than measured maxima. This difference may be due to partial isotopic equilibration or may reflect the origin of the methane. Present evidence cannot identify whether the methane is primordial, or from decomposing sediments or from reduction of magmatic CO 2. The isotopic equilibria between CH 4, CO 2, H 2 and H 2O are reviewed and a new semi-empirical temperature scale proposed for deuterium exchange between methane and water.

  1. Density dependence of the deexcitation dynamics of kaonic hydrogen and deuterium atoms formed in kaon transmission through gaseous hydrogen and deuterium targets

    NASA Astrophysics Data System (ADS)

    Raeisi G., M.; Kalantari, S. Z.

    2009-01-01

    The cascade calculations presented have led to a more detailed understanding of the atomic cascade in K-x (where x can be either p or d ) atoms. The density dependence of the K -series x-ray yields of kaonic hydrogen and deuterium atoms is investigated. It shows that two processes, nuclear absorption and Stark mixing, have an important role in atomic cascades at high-density targets. ?2p=0.105±0.002meV is approximately suggested for the 2p strong interaction width of K-p atoms by fitting our results with existing experimental data. In order to obtain the optimum density for measurement of the 1s strong interaction shift and width, we have investigated the stopping power of kaons in the targets together with the x-ray yields of kaonic hydrogen and deuterium. We have predicted the optimum range of the target density ??0.03-0.06 of liquid hydrogen density (LHD) for K-p atoms and ??0.06-0.2 of LHD for K-d atoms in a forthcoming SIDDHARTA experiment.

  2. Kinetic isotope effect in hydrogen abstraction from 2-propanol by hydrogen and deuterium radicals. A pulse radiolysis Fourier transform electron spin resonance study

    Microsoft Academic Search

    J. Geimer; D. Beckert; A. Jenichen

    1997-01-01

    Using FT-ESR coupled with pulse radiolysis the kinetics of hydrogen abstraction from 2-propanol by hydrogen and deuterium radicals were studied in aqueous solution. The rate constants were determined from the effective spin–spin relaxation times of the free induction decay of hydrogen or deuterium ESR lines by variation of the 2-propanol concentration. The rate constants kHH and kDH for H(D)+2-propanol-h8 and

  3. Biogeochemistry of the Stable Isotopes of Hydrogen and Carbon in Salt Marsh Biota 1

    PubMed Central

    Smith, Bruce N.; Epstein, Samuel

    1970-01-01

    Deuterium to hydrogen ratios of 14 plant species from a salt marsh and lagoon were 55‰ depleted in deuterium relative to the environmental water. Carbon tetrachloride-extractable material from these plants was another 92‰ depleted in deuterium. This gave a fractionation factor from water to CCl4 extract of 1.147. This over-all fractionation was remarkably constant for all species analyzed. Plants also discriminate against 13C, particularly in the lipid fraction. Data suggest that different mechanisms for carbon fixation result in different fractionations of the carbon isotopes. Herbivore tissues reflected the isotopic ratios of plants ingested. Apparently different metabolic processes are responsible for the different degrees of fractionation observed for hydrogen and carbon isotopes. PMID:16657539

  4. Hydrogen and deuterium NMR of solids by magic-angle spinning

    SciTech Connect

    Eckman, R.R.

    1982-10-01

    The nuclear magnetic resonance of solids has long been characterized by very large specral broadening which arises from internuclear dipole-dipole coupling or the nuclear electric quadrupole interaction. These couplings can obscure the smaller chemical shift interaction and make that information unavailable. Two important and difficult cases are that of hydrogen and deuterium. The development of cross polarization, heteronuclear radiofrequency decoupling, and coherent averaging of nuclear spin interactions has provided measurement of chemical shift tensors in solids. Recently, double quantum NMR and double quantum decoupling have led to measurement of deuterium and proton chemical shift tensors, respectively. A general problem of these experiments is the overlapping of the tensor powder pattern spectra of magnetically distinct sites which cannot be resolved. In this work, high resolution NMR of hydrogen and deuterium in solids is demonstrated. For both nuclei, the resonances are narrowed to obtain liquid-like isotropic spectra by high frequency rotation of the sample about an axis inclined at the magic angle, ..beta../sub m/ = Arccos (3/sup -1/2/), with respect to the direction of the external magnetic field. For deuterium, the powder spectra were narrowed by over three orders of magnitude by magic angle rotation with precise control of ..beta... A second approach was the observation of deuterium double quantum transitions under magic angle rotation. For hydrogen, magic angle rotation alone could be applied to obtain the isotropic spectrum when H/sub D/ was small. This often occurs naturally when the nuclei are semi-dilute or involved in internal motion. In the general case of large H/sub D/, isotropic spectra were obtained by dilution of /sup 1/H with /sup 2/H combined with magic angle rotation. The resolution obtained represents the practical limit for proton NMR of solids.

  5. Definitive proof of graphene hydrogenation by Clemmensen reduction: use of deuterium labeling.

    PubMed

    Sofer, Zden?k; Jankovský, Ond?ej; Libánská, Alena; Šimek, Petr; Nová?ek, Michal; Sedmidubský, David; Macková, Anna; Mikšová, Romana; Pumera, Martin

    2015-06-01

    Graphane is one of the most intensively studied derivatives of graphene. Here we demonstrate the evaluation of exact degree of graphene hydrogenation using the Clemmensen reduction reaction and deuterium labeling. The Clemmensen reduction reaction is based on application of zinc in an acid environment. It effectively reduces various functional groups (like ketones) present in graphite oxide. However, the mechanism of reduction is still unknown and elusive. Here we bring a major insight into the mechanisms of the Clemmensen reduction via deuterium labeling and the topochemical approach applied on graphite oxide. The use of deuterated reactants and the exact measurement of deuterium concentration in reduced/hydrogenated graphene by nuclear methods can be used for accurate estimation of C-H bond abundance in graphene. Various topochemical configurations of experiments showed that the reduction of a ketonic group proceeds in contact with the zinc metal by a carbenoid mechanism. Our results showed that the application of nuclear methods of isotope analysis in combination with deuterium labeling represents a very effective tool for investigation of graphene based materials. Our results demonstrate that graphene based materials can also be effectively used for the investigation of organic reaction mechanisms, because the robust structure of graphene allows the use of various spectroscopic techniques which could not be applied on small organic molecules. PMID:26015058

  6. Effects of atomic hydrogen and deuterium exposure on high polarization GaAs photocathodes

    SciTech Connect

    M. Baylac; P. Adderley; J. Brittian; J. Clark; T. Day; J. Grames; J. Hansknecht; M. Poelker; M. Stutzman; A. T. Wu; A. S. Terekhov

    2005-12-01

    Strained-layer GaAs and strained-superlattice GaAs photocathodes are used at Jefferson Laboratory to create high average current beams of highly spin-polarized electrons. High electron yield, or quantum efficiency (QE), is obtained only when the photocathode surface is atomically clean. For years, exposure to atomic hydrogen or deuterium has been the photocathode cleaning technique employed at Jefferson Laboratory. This work demonstrates that atomic hydrogen cleaning is not necessary when precautions are taken to ensure that clean photocathode material from the vendor is not inadvertently dirtied while samples are prepared for installation inside photoemission guns. Moreover, this work demonstrates that QE and beam polarization can be significantly reduced when clean high-polarization photocathode material is exposed to atomic hydrogen from an rf dissociator-style atomic hydrogen source. Surface analysis provides some insight into the mechanisms that degrade QE and polarization due to atomic hydrogen cleaning.

  7. Diffusion of hydrogen, deuterium, and tritium in niobium

    Microsoft Academic Search

    Matusiewicz

    1981-01-01

    The diffusion of hydrogen in niobium was investigated over the temperature range 148 to 500 degrees Kelvin, using measurements of the elastic after effect caused by long range diffusion (the Gorsky Effect). Relaxation curves for pure annealed niobium were generally not of the single exponential form expected from the Gorsky Effect theory, but were described well by a sum of

  8. Hydrogen Storage in Amorphous Phase of Hydrogenated Carbon Nitride

    NASA Astrophysics Data System (ADS)

    Ohkawara, Yoshiaki; Ohshio, Shigeo; Suzuki, Tsuneo; Yatsui, Kiyoshi; Ito, Haruhiko; Saitoh, Hidetoshi

    2002-12-01

    A hydrogen storage characteristic of amorphous phase of hydrogenated carbon nitride (a-CNx:H) was evaluated at room temperature under high-pressure hydrogen. The hydrogen content in the sample was directly measured using a volumetric analysis established for measuring the hydrogen adsorption of metal alloys. The content of stored hydrogen in a-CNx:H was twice as much as those of multiwalled nanotubes, charcoal activated powder and carbon fiber.

  9. IUE observations of hydrogen and deuterium in the local interstellar medium

    SciTech Connect

    Murthy, J.; Henry, R.C.; Moos, H.W.; Landsman, W.B.; Linsky, J.L.

    1987-04-01

    High-resolution Ly-alpha spectra of the late-type stars Epsilon Eri, Procyon, Altair, Capella, and HR 1099 taken with the short-wavelength camera on IUE are presented. The density, velocity dispersion, and bulk velocity of the interstellar H I toward each of the stars is derived from the spectra. Lower limits on the deuterium-to-hydrogen ratio toward these stars are obtained. 40 references.

  10. Hydrogen\\/deuterium exchange of hydrophobic peptides in model membranes by electrospray ionization mass spectrometry

    Microsoft Academic Search

    Raino K. Hansen; R. William Broadhurst; Paul C. Skelton; Isaiah T. Arkin

    2002-01-01

    We demonstrate here that the hydrogen\\/deuterium solvent exchange (HDX) properties of the transmembrane fragment of the M2\\u000a protein of Influenza A (M2-TM) incorporated into lipid vesicles or detergent micelles can be studied with straightforward electrospray (ESI) and\\u000a nanospray mass spectrometry (MS) configurations provided that key factors, including sample preparation techniques, are optimized.\\u000a Small unilamellar vesicle preparations were obtained by solubilizing

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

    Microsoft Academic Search

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

    2010-01-01

    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 ?D

  12. Solubility of hydrogen and deuterium in bcc uranium–titanium alloys

    Microsoft Academic Search

    G. L Powell; J. R Kirkpatrick

    1997-01-01

    For the body-centered-cubic uranium–titanium alloy system, hydrogen and deuterium solubility measurements have been made on 12 alloy specimens ranging in composition from pure uranium to pure titanium and over a temperature range of 900–1473 K. The results are described in closed form by an analytical model within a standard error of 3%. The Einstein temperature (1680 K), and thus the

  13. Excitation of Balmer lines in low-current discharges of hydrogen and deuterium

    Microsoft Academic Search

    Z. Stokic; M. M. F. R. Fraga; J. Bozin; V. Stojanovic; Z. Lj. Petrovic; B. M. Jelenkovic

    1992-01-01

    Measurements have been made of electron-impact ionization and excitation of Balmer lines in low-current, steady-state discharges of hydrogen and deuterium. Results were obtained from spatial scans of Halpha lines for E\\/N ranging from 250 Td to 10 kTd. Here E is the electric field, N is the gas density, and 1 Td=10-21 V m2. Ionization and excitation coefficients versus E\\/N

  14. Experimental and modeling study of hydrogenation using deuterium step transient response during ethylene hydroformylation

    SciTech Connect

    Brundage, M.A.; Chuang, S.S.C. [Univ. of Akron, OH (United States)] [Univ. of Akron, OH (United States)

    1996-11-01

    Deuterium isotopic step tracing combined with in situ infrared (IR) spectroscopy was utilized to study and model the hydrogenation steps in ethylene hydroformylation on 4 wt% Rh/SiO{sub 2} at 483-573 K and 0.1 MPa. The difference in residence times between H{sub 2} and D{sub 2}, as well as propionaldehyde and deuterated propionaldehyde to the step switch from H{sub 2} to D{sub 2} and D{sub 2} to H{sub 2} during ethylene hydroformylation reflects the presence of an isotope effect for H{sub 2}/D{sub 2} chemisorption and propionaldehyde formation. Compartment modeling of H{sub 2}/D{sub 2} responses and qualitative comparison of propionaldehyde and deuterated propionaldehyde responses unravel the presence of a normal equilibrium isotope effect for H{sub 2}/D{sub 2} chemisorption and a normal kinetic isotope effect for hydrogenation/deuteration of adsorbed acyl species. In situ IR coupled with deuterium transient responses shows that the reverse spillover of deuterium from Si-OD participates in the deuteration of adsorbed acyl species, suggesting that the site for deuteration of the adsorbed species, suggesting that the site for deuteration of the adsorbed acyl species is located near the Rh and SiO{sub 2} interface. Significant difference in the deuterated ethane and propionaldehyde responses suggests the different nature of either adsorbed hydrogen/deuterium or the active site for hydrogenation/deuteration of adsorbed ethyl and acyl species. 31 refs., 12 figs., 6 tabs.

  15. Isentropes and Hugoniot curves for dense hydrogen and deuterium

    Microsoft Academic Search

    Dieter Beule; Werner Ebeling; Andreas Förster; Hauke Juranek; Ronald Redmer; Gerd Röpke

    2001-01-01

    Multiple-shock experiments with fluid hydrogen have shown that a transition from semiconducting behavior to metal-like conductivity occurs at pressures (p) of about 140 GPa and temperatures (T) near 3000 K. We model the p-T pathway by Hugoniot curves (initial shock) and isentropes (subsequent shocks). For the calculation of these curves we apply an expression for the free energy developed recently

  16. Optimization Study of ICRF Hydrogen Minority Heating in a Deuterium Plasma of EAST

    NASA Astrophysics Data System (ADS)

    Zhang, Xinjun; Yao, Fangwei

    2015-06-01

    The full wave TORIC code and the Kinetic Fokker-Planck SSFPQL code are combined to perform self-consistent simulations of the ICRF heating in the EAST 2D magnetic configuration. The combined package is applied to the ICRF hydrogen minority heating in a deuterium plasma with the hydrogen concentration up to 10%. The fast wave propagation and absorption properties, power partitions among the plasma species and the RF driven energetic tails have been analyzed. Meanwhile, in order to optimize the ICRF heating, changing the resonance locations has also been considered in EAST plasmas. supported by National Natural Science Foundation of China (Nos. 11105179, 11375235 and 11375236)

  17. Two-chamber hydrogen generation and application: access to pressurized deuterium gas.

    PubMed

    Modvig, Amalie; Andersen, Thomas L; Taaning, Rolf H; Lindhardt, Anders T; Skrydstrup, Troels

    2014-06-20

    Hydrogen and deuterium gas were produced and directly applied in a two-chamber system. These gaseous reagents were generated by the simple reaction of metallic zinc with HCl in water for H2 and DCl in deuterated water for D2. The setup proved efficient in classical Pd-catalyzed reductions of ketones, alkynes, alkenes, etc. in near-quantitative yields. The method was extended to the synthesis and isotope labeling of quinoline and 1,2,3,4-tetrahydroquinoline derivatives. Finally, CX-546 and Olaparib underwent efficient Ir-catalyzed hydrogen isotope exchange reactions. PMID:24870212

  18. The solubility of hydrogen and deuterium in alloyed, unalloyed and impure plutonium metal

    SciTech Connect

    Richmond, Scott [Los Alamos National Laboratory; Bridgewater, Jon S [Los Alamos National Laboratory; Ward, John W [Los Alamos National Laboratory; Allen, Thomas A [Los Alamos National Laboratory

    2009-01-01

    Pressure-Composition-Temperature (PCT) data are presented for the plutonium-hydrogen (Pu-H) and plutonium-deuterium (Pu-D) systems in the solubility region up to terminal solubility (precipitation of PuH{sub 2}). The heats of solution for PuH{sub s} and PuD{sub s} are determined from PCT data in the ranges 350-625 C for gallium alloyed Pu and 400-575 C for unalloyed Pu. The solubility of high purity plutonium alloyed with 2 at.% gallium is compared to high purity unalloyed plutonium. Significant differences are found in hydrogen solubility for unalloyed Pu versus gallium alloyed Pu. Differences in hydrogen solubility due to an apparent phase change are observable in the alloyed and unalloyed solubilities. The effect of iron impurities on Pu-Ga alloyed Pu is shown via hydrogen solubility data as preventing complete homogenization.

  19. Raman measurements of phase transitions in dense solid hydrogen and deuterium to 325 GPa

    PubMed Central

    Zha, Chang-sheng; Cohen, R. E.; Mao, Ho-kwang; Hemley, Russell J.

    2014-01-01

    Raman spectroscopy of dense hydrogen and deuterium performed to 325 GPa at 300 K reveals previously unidentified transitions. Detailed analysis of the spectra from multiple experimental runs, together with comparison with previous infrared and Raman measurements, provides information on structural modifications of hydrogen as a function of density through the I–III–IV transition sequence, beginning near 200 GPa at 300 K. The data suggest that the transition sequence at these temperatures proceeds by formation of disordered stacking of molecular and distorted layers. Weaker spectral changes are observed at 250, 285, and 300 GPa, that are characterized by discontinuities in pressure shifts of Raman frequencies, and changes in intensities and linewidths. The results indicate changes in structure and bonding, molecular orientational order, and electronic structure of dense hydrogen at these conditions. The data suggest the existence of new phases, either variations of phase IV, or altogether new structures. PMID:24639543

  20. Automatic analysis of hydrogen\\/deuterium exchange mass spectra of peptides and proteins using calculations of isotopic distributions

    Microsoft Academic Search

    Magnus Palmblad; Jos Buijs; Per Håkansson

    2001-01-01

    High mass-resolving power has been shown to be useful for studying the conformational dynamics of proteins by hydrogen\\/deuterium\\u000a (H\\/D) exchange. A computer algorithm was developed that automatically identifies peptides and their extent of deuterium incorporation\\u000a from H\\/D exchange mass spectra of enzymatic digests or fragment ions produced by collisionally induced dissociation (CID)\\u000a or electron capture dissociation (ECD). The computer algorithm

  1. A centroid molecular dynamics study of liquid para-hydrogen and ortho-deuterium.

    PubMed

    Hone, Tyler D; Voth, Gregory A

    2004-10-01

    Centroid molecular dynamics (CMD) is applied to the study of collective and single-particle dynamics in liquid para-hydrogen at two state points and liquid ortho-deuterium at one state point. The CMD results are compared with the results of classical molecular dynamics, quantum mode coupling theory, a maximum entropy analytic continuation approach, pair-product forward- backward semiclassical dynamics, and available experimental results. The self-diffusion constants are in excellent agreement with the experimental measurements for all systems studied. Furthermore, it is shown that the method is able to adequately describe both the single-particle and collective dynamics of quantum liquids. PMID:15446940

  2. High-temperature diffusion of hydrogen and deuterium in titanium and TiâAl

    Microsoft Academic Search

    Shizuo Naito; Masahiro Yamamoto; Minoru Doi; Masao Kimura

    1998-01-01

    Diffusion coefficients (D{sub H} and D{sub D}) of hydrogen (H) and deuterium (D) in β-titanium (Ti) and β-TiâAl have been obtained from the rates of gaseous H and D absorption by samples in the temperature ranges of 1,173 to 1,473 K for β-Ti and 1,423 to 1,523 K for β-TiâAl. Activation energies for diffusion (ε{sub d}) are found to be

  3. Determination of hydrogen/deuterium ratio with neutron measurements on MAST.

    PubMed

    Klimek, I; Cecconello, M; Sharapov, S E; Harrison, J; Ericsson, G

    2014-11-01

    On MAST, compressional Alfvén eigenmodes can be destabilized by the presence of a sufficiently large population of energetic particles in the plasma. This dependence was studied in a series of very similar discharges in which increasing amounts of hydrogen were puffed into a deuterium plasma. A simple method to estimate the isotopic ratio nH/nD using neutron emission measurements is here described. The inferred isotopic ratio ranged from 0.0 to 0.6 and no experimental indication of changes in radial profile of nH/nD were observed. These findings are confirmed by TRANSP/NUBEAM simulations of the neutron emission. PMID:25430288

  4. Online deuterium hydrogen exchange and protein digestion coupled with ion mobility spectrometry and tandem mass spectrometry.

    PubMed

    Donohoe, Gregory C; Arndt, James R; Valentine, Stephen J

    2015-05-19

    Online deuterium hydrogen exchange (DHX) and pepsin digestion (PD) is demonstrated using drift tube ion mobility spectrometry (DTIMS) coupled with linear ion trap (LTQ) mass spectrometry (MS) with electron transfer dissociation (ETD) capabilities. DHX of deuterated ubiquitin, followed by subsequent quenching and digestion, is performed within ?60 s, yielding 100% peptide sequence coverage. The high reproducibility of the IMS separation allows spectral feature matching between two-dimensional IMS-MS datasets (undeuterated and deuterated) without the need for dataset alignment. Extracted ion drift time distributions (XIDTDs) of deuterated peptic peptides are mobility-matched to corresponding XIDTDs of undeuterated peptic peptides that were identified using collision-induced dissociation (CID). Matching XIDTDs allows a straightforward identification and deuterium retention evaluation for labeled peptides. Aside from the mobility separation, the ion trapping capabilities of the LTQ, combined with ETD, are demonstrated to provide single-residue resolution. Deuterium retention for the c- series ions across residues M(1)-L(15) and N(25)-R(42) are in good agreement with the known secondary structural elements within ubiquitin. PMID:25893550

  5. Origin of Terrestrial Water: Hydrogen/Deuterium Fractionation into Earth's Core

    NASA Astrophysics Data System (ADS)

    Wu, J.; Buseck, P. R.

    2014-12-01

    Hydrogen isotopic compositions are among the most important constraints on the origin of Earth's water. Earth's bulk water content, which is small but not negligible, is significantly greater than what the thermal gradient of the solar nebula disk would suggest for planetesimal materials condensed at one astronomical unit. The proto-solar nebula is a likely source of early Earth's water, with probable contributions from one or more of the following: water-rich planetesimals, ordinary and carbonaceous meteorites, comets, asteroids, and interplanetary dust particles. However, all of these sources have been questioned, and the proposed proto-solar nebular origin has been disputed in light of the large difference in hydrogen isotopic composition between it and terrestrial water. Current opposition to the solar nebular hypothesis is based on the critical assumption that no processes in the interior of the early Earth changed the isotopic composition of hydrogen. Nevertheless, a hypothesized hydrogenation reaction of liquid iron (2Fe + xH2 ? 2FeHx) during core formation likely provided a fractionation mechanism between hydrogen and deuterium (D). We propose that modern D/H ratios at Earth's surface resulted from this isotopic fractionation and that terrestrial water originated from oxidation of proto-solar hydrogen dissolved in the magma ocean in the early Earth by coexisting oxides (such as FeO). Thus, the isotopic composition of water on Earth can be mainly explained by internal terrestrial processes.

  6. The torque dependence of the H-mode power threshold in hydrogen, deuterium and helium plasmas in DIII-D

    SciTech Connect

    Gohil, P. [General Atomics; Jernigan, T. C. [Oak Ridge National Laboratory (ORNL); Osborne, T.H. [General Atomics, San Diego; Scoville, J. T. [General Atomics, San Diego; Strait, E. J. [General Atomics

    2010-01-01

    On DIII-D, the H-mode power threshold has been determined for hydrogen, deuterium and helium plasmas heated by neutral beam injection and/or by electron cyclotron heating and as a function of the applied torque plasmas for plasma configurations in the favourable ion grad-B drift direction. The H-mode threshold power has been determined to increase with input torque for all the main ion species (hydrogen, deuterium and helium). The H-mode threshold power for similar plasma parameters and configurations is the least for deuterium, followed by helium and hydrogen in that order. The plasma geometry also affects the power threshold, which is dependent on the X-point height.

  7. Deposition and in-depth penetration of deuterium in carbon fibre composites

    NASA Astrophysics Data System (ADS)

    Rubel, M.; Emmoth, B.; Bergsker, H.; Wienhold, P.; Dunaev, V.; Sukhomlinov, V.

    1992-12-01

    Deposition, retention and in-depth penetration of deuterium was investigated in carbon fibre composites (CFC). Comparative studies were also performed for isotropic graphite and carbon-silicon (5 or 20% Si) composites. The materials were exposed to fluxes of deuterium in a hollow cathode device and in the TEXTOR tokamak. The irradiated targets were studied by a number of techniques in order to characterize their surface composition and structure. Nuclear reaction analysis, Rutherford backscattering spectroscopy, laser profilometry, crystallographic as well as microscopic methods were applied, and thermally and ion induced release were studied. The studies performed in several time steps revealed a systematic decrease of the deuterium content in the near surface layer (1.5 ?m thick) of CFC substrates exposed to the hollow cathode plasma: from 6.8×10 18 cm -2 to 4.18×10 18 cm -2 and 3.76×10 18 cm -2 after 1, 81 and 112 days following the exposure, respectively. Moreover, in these samples a pronounced content of deuterium, even 60 times higher than the background level, was found beneath the exposed surface indicating deep penetration of D atoms through the layered structure of CFC. Thermally stimulated desorption at 1100°C resulted in the release of more than 99.9% of D atoms from the substrate. The disappearance of deuterium was accompanied by topographical changes of the surface layer as observed by scanning electron microscopy.

  8. Hydrogen and deuterium incorporation and transport in hafnium-based dielectric films on silicon

    SciTech Connect

    Pezzi, R.P.; Miotti, L.; Bastos, K.P.; Soares, G.V.; Driemeier, C.; Baumvol, I.J.R.; Punchaipetch, P.; Pant, G.; Gnade, B.E.; Wallace, R.M.; Rotondaro, A.; Visokay, J.M.; Chambers, J.J.; Colombo, L. [Instituto de Fisica, UFRGS, Av. Bento Goncalves, 9500, Porto Alegre, RS, Brazil 91509-900 (Brazil); Centro de Ciencias Exatas e Tecnologicas, UCS, Caxias do Sul, RS, Brazil 95070-560 (Brazil); Department of Electrical Engineering, University of Texas at Dallas, Richardson, Texas 75083 (United States); Silicon Technology Development, Texas Instruments Incorporated, Dallas, Texas (United States)

    2004-10-18

    Hydrogen and deuterium incorporation into nitrided and non-nitrided hafnium silicate films on Si during thermal annealing in {sup 1}H- and {sup 2}H-containing atmospheres was investigated. {sup 1}H profiling was accessed by means of nuclear resonant reaction profiling, whereas {sup 2}H incorporation was quantified by nuclear reaction analysis. The effects of preannealing in different atmospheres and temperatures were determined, as well as the losses of {sup 1}H and {sup 2}H from these structures during postannealing in vacuum. The results reveal a rather uniform depth distribution of incorporated {sup 1}H, in striking contrast with previous studies on hydrogen in silicon oxide and oxynitrides and hafnium oxide films on Si. These results are discussed in terms of the defects present in each one of the structures studied here.

  9. Detection of deuterium and hydrogen using laser-induced helium gas plasma at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Kurniawan, Koo Hendrik; Lie, Tjung Jie; Suliyanti, Maria Margaretha; Hedwig, Rinda; Abdulmadjid, Syahrun Nur; Pardede, Marincan; Idris, Nasrullah; Kobayashi, Takao; Kusumoto, Yoshihumi; Kagawa, Kiichiro; Tjia, May On

    2005-11-01

    An experimental study on gas analysis by means of laser-induced breakdown spectroscopy was conducted using a Nd-yttrium aluminum garnet laser (1,064 nm, 120 mJ, 8 ns) and helium host gas at atmospheric pressure on a sample of mixed water (H2O) and heavy water (D2O) in vapor form. It was shown that completely resolved hydrogen (H?) and deuterium (D?) emission lines that are separated by only 0.179 nm could be obtained at a properly delayed detection time when the charged particles responsible for the strong Stark broadening effect in the plasma have mostly disappeared. It is argued that the helium metastable excited state plays an important role in the hydrogen excitation process.

  10. Permeation of several gases through elastomers, with emphasis on the deuterium/hydrogen pair

    SciTech Connect

    Fitch, M.W.; Koros, W.J. (Univ. of Texas, Austin (United States)); Nolen, R.L.; Carnes, J.R. (Los Alamos National Lab., NM (United States))

    1993-02-10

    The diffusion and permeation coefficients for He, H[sub 2], D[sub 2], O[sub 2], and N[sub 2] in a variety of elastomers were measured by simple manometric methods. The elastomers studied were butyl rubber; Hypalon[reg sign] 40 and 45; Viton[reg sign] E60 and GF; Hydrin[reg sign] 100 and filled Hydrin[reg sign] 100; Kraton[reg sign] G, FG, and KG VTEOS; EPDM; epoxidized natural rubber; and neoprene. Consistent with earlier studies, elastomers with higher glass transition temperatures exhibited lower diffusion coefficients. The ratio of diffusion coefficients of the hydrogen isotope pair differed from the purely molecular-weight-based prediction. Deuterium's slightly smaller size relative to hydrogen is consistent with observed deviations from the molecular-weight-based diffusion coefficient ratio.

  11. Pulsed hydrogen–deuterium exchange mass spectrometry probes conformational changes in amyloid beta (A?) peptide aggregation

    PubMed Central

    Zhang, Ying; Rempel, Don L.; Zhang, Jun; Sharma, Anuj K.; Mirica, Liviu M.; Gross, Michael L.

    2013-01-01

    Probing the conformational changes of amyloid beta (A?) peptide aggregation is challenging owing to the vast heterogeneity of the resulting soluble aggregates. To investigate the formation of these aggregates in solution, we designed an MS-based biophysical approach and applied it to the formation of soluble aggregates of the A?42 peptide, the proposed causative agent in Alzheimer’s disease. The approach incorporates pulsed hydrogen–deuterium exchange coupled with MS analysis. The combined approach provides evidence for a self-catalyzed aggregation with a lag phase, as observed previously by fluorescence methods. Unlike those approaches, pulsed hydrogen–deuterium exchange does not require modified A?42 (e.g., labeling with a fluorophore). Furthermore, the approach reveals that the center region of A?42 is first to aggregate, followed by the C and N termini. We also found that the lag phase in the aggregation of soluble species is affected by temperature and Cu2+ ions. This MS approach has sufficient structural resolution to allow interrogation of A? aggregation in physiologically relevant environments. This platform should be generally useful for investigating the aggregation of other amyloid-forming proteins and neurotoxic soluble peptide aggregates. PMID:23959898

  12. Hydrogen-deuterium exchange in imidazole as a tool for studying histidine phosphorylation.

    PubMed

    Cebo, Ma?gorzata; Kielmas, Martyna; Adamczyk, Justyna; Cebrat, Marek; Szewczuk, Zbigniew; Stefanowicz, Piotr

    2014-12-01

    Isotope exchange at the histidine C2 atom of imidazole in D2O solution is well known to occur at a significantly slower rate than the exchange of amide protons. Analysis of the kinetics of this isotope-exchange reaction is proposed herein as a method of detecting histidine phosphorylation. This modification of His-containing peptides is challenging to pinpoint because of its instability under acidic conditions as well as during CID-MS analysis. In this work, we investigated the effect of phosphorylation of the histidine side chain in peptides on deuterium-hydrogen exchange (DHX) in the imidazole. The results demonstrate that phosphorylation dramatically slows the rate of the DHX reaction. This phenomenon can be applied to detect phosphorylation of peptides at the histidine residue (e.g., in enzymatic digests). We also found that the influence of the peptide sequence on the exchange kinetics is relatively small. A CID fragmentation experiment revealed that there was no detectable hydrogen scrambling in peptides deuterated at C2 of the imidazole ring. Therefore, MS/MS can be used to directly identify the locations of deuterium ions incorporated into peptides containing multiple histidine moieties. PMID:25354888

  13. Longitudinal-Transverse Separations of Deep-Inelastic Structure Functions at Low Q{sup 2} for Hydrogen and Deuterium

    SciTech Connect

    Tvaskis, V.; Blok, H. P. [Vrije Universiteit, 1081 HV Amsterdam (Netherlands); National Instituut voor Kernfysica en Hoge-Energiefysica (NIKHEF), 1009 DB Amsterdam (Netherlands); Christy, M. E.; Baker, O. K.; Cochran, A.; Cole, L.; Gasparian, A.; Nazaryan, V.; Sato, Y.; Uzzle, A. [Hampton University, Hampton, Virginia 23668 (United States); Arrington, J.; Jackson, H. E.; Potterveld, D. H. [Argonne National Laboratory, Argonne, Illinois 60439 (United States); Asaturyan, R.; Mkrtchyan, H.; Stepanyan, S.; Tadevosian, V. [Yerevan Physics Institute, 375036, Yerevan (Armenia); Bosted, P.; Ent, R.; Fenker, H. C. [Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States)] (and others)

    2007-04-06

    We report on a study of the longitudinal to transverse cross section ratio, R={sigma}{sub L}/{sigma}{sub T}, at low values of x and Q{sup 2}, as determined from inclusive inelastic electron-hydrogen and electron-deuterium scattering data from Jefferson Laboratory Hall C spanning the four-momentum transfer range 0.06hydrogen and deuterium.

  14. In situ study of erosion and deposition of amorphous hydrogenated carbon films by exposure to a hydrogen atom beam

    SciTech Connect

    Markelj, Sabina; Pelicon, Primoz; Cadez, Iztok; Schwarz-Selinger, Thomas; Jacob, Wolfgang [Jozef Stefan Institute and Association EURATOM-MHEST, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Max-Planck-Institut fuer Plasmaphysik (IPP), EURATOM Association, Boltzmannstr. 2, D-85748 Garching (Germany)

    2012-07-15

    This paper reports on the first dual-beam experiment employing a hydrogen atom beam for sample exposure and an ion beam for analysis, enabling in situ and real-time studies of hydrogen atom interaction with materials. The erosion of an amorphous hydrogenated carbon (a-C:H) layer by deuterium atoms at 580 K sample temperature was studied and the uptake of deuterium during the erosion process was measured in real time. The deuterium areal density increased at the beginning to 7.3 Multiplication-Sign 10{sup 15} D cm{sup -2}, but then stabilized at a constant value of 5.5 Multiplication-Sign 10{sup 15} D cm{sup -2}. Formation of a polymer-like deposit on an a-C:H layer held at room temperature and subjected to the deuterium atom beam was observed and also studied in situ. For both erosion and deposition studies an a-{sup 13}C:H layer on top of an Si substrate was used as a sample, making the experiments isotopically fully specified and thereby differentiating the deposited from the original layer and the interacting D atoms from H atoms present in the layer and in the residual vacuum. From the deposition study it was shown that carbon in the deposited layer originates from carbon-carrying species in the background vacuum that interact with hydrogen atoms. The areal density of the carbon at the surface was determined from the energy shift of the Si edge in the Rutherford backscattering spectrum. The cross section for {sup 7}Li on D at 4.3 MeV Li ion energy and at a recoil angle of 30 Degree-Sign was also determined to be (236 {+-} 16) Multiplication-Sign 10{sup -27} cm{sup 2}/sr. This is a factor of 3 {+-} 0.2 times higher than the Rutherford elastic cross section.

  15. Catalytic hydrogenation of carbon monoxide

    SciTech Connect

    Wayland, B.B.

    1992-12-01

    This project is focused on developing strategies to accomplish the reduction and hydrogenation of carbon monoxide to produce organic oxygenates at mild conditions. Our approaches to this issue are based on the recognition that rhodium macrocycles have unusually favorable thermodynamic values for producing a series of intermediate implicated in the catalytic hydrogenation of CO. Observations of metalloformyl complexes produced by reactions of H{sub 2} and CO, and reductive coupling of CO to form metallo {alpha}-diketone species have suggested a multiplicity of routes to organic oxygenates that utilize these species as intermediates. Thermodynamic and kinetic-mechanistic studies are used in constructing energy profiles for a variety of potential pathways, and these schemes are used in guiding the design of new metallospecies to improve the thermodynamic and kinetic factors for individual steps in the overall process. Variation of the electronic and steric effects associated with the ligand arrays along with the influences of the reaction medium provide the chemical tools for tuning these factors. Emerging knowledge of the factors that contribute to M-H, M-C and M-O bond enthalpies is directing the search for ligand arrays that will expand the range of metal species that have favorable thermodynamic parameters to produce the primary intermediates for CO hydrogenation. Studies of rhodium complexes are being extended to non-macrocyclic ligand complexes that emulate the favorable thermodynamic features associated with rhodium macrocycles, but that also manifest improved reaction kinetics. Multifunctional catalyst systems designed to couple the ability of rhodium complexes to produce formyl and diketone intermediates with a second catalyst that hydrogenates these imtermediates are promising approaches to accomplish CO hydrogenation at mild conditions.

  16. The effect of hydrogen/deuterium introduction on photoluminescence of 3C-SiC crystals

    SciTech Connect

    Lee, B.K.; Steckl, A.J. [Univ. of Cincinnati, OH (United States). Nanoelectronics Lab.; Zavada, J.M. [Army Research Office, Research Triangle Park, NC (United States); Wilson, R.G. [Hughes Research Labs., Malibu, CA (United States)

    1998-12-31

    The effect of the incorporation and annealing of deuterium in 3C-SiC on its photoluminescence is reported. A 3C-SiC crystal has been implanted with 100 kev deuterium and subsequently annealed at temperatures between 1015 C and 1220 C for 1 to 5 minutes. SIMS depth profiles indicate hydrogen is strongly trapped by defects generated through ion bombardment, but a gradual damage repairing occurs during annealing. Photoluminescence was measured with 488 nm Ar laser excitation for sample temperatures from 89 K to 400 K. The PL peak wavelength of 540 nm at room temperature has shifted to 538 nm at 89 K. The peak PL intensity decreases with measurement temperature while its full width at half maximum (FWHM) exhibits an increasing trend. PL data were taken at five annealing stages. The post-implantation peak PL intensity and its integrated area increase initially with annealing temperature and time. After the final annealing at 1218 C for 2 minute, PL intensity and its integrated area exhibit a decrease in level.

  17. Localized Hydration in Lyophilized Myoglobin by Hydrogen-Deuterium Exchange Mass Spectrometry. 2. Exchange Kinetics

    PubMed Central

    Sophocleous, Andreas M.; Topp, Elizabeth M.

    2012-01-01

    Solid-state hydrogen deuterium exchange with mass spectrometric analysis (ssHDX) is a promising method for characterizing proteins in amorphous solids. Though analysis of HDX kinetics is informative and well-established in solution, application of these methods to solid samples is complicated by possible heterogeneities in the solid. The studies reported here provide a detailed analysis of the kinetics of hydration and ssHDX for equine myoglobin (Mb) in solid matrices containing sucrose or mannitol. Water sorption was rapid relative to ssHDX, indicating that ssHDX kinetics was not limited by bulk water transport. Deuterium uptake in solids was well-characterized by a bi-exponential model; values for regression parameters provided insight into differences between the two solid matrices. Analysis of the widths of peptide mass envelopes revealed that in solution, an apparent EX2 mechanism prevails, consistent with native conformation of the protein. In contrast, in mannitol-containing samples, a smaller non-native subpopulation exchanges by an EX1-like mechanism. Together, the results indicate that the analysis of ssHDX kinetic data and the widths of peptide mass envelopes are useful in screening solid formulations of protein drugs for the presence of non-native species that cannot be detected by amide I FTIR. PMID:22352990

  18. Advantages of isotopic depletion of proteins for hydrogen/deuterium exchange experiments monitored by mass spectrometry.

    PubMed

    Bou-Assaf, George M; Chamoun, Jean E; Emmett, Mark R; Fajer, Piotr G; Marshall, Alan G

    2010-04-15

    Solution-phase hydrogen/deuterium exchange (HDX) monitored by mass spectrometry is an excellent tool to study protein-protein interactions and conformational changes in biological systems, especially when traditional methods such as X-ray crystallography or nuclear magnetic resonance are not feasible. Peak overlap among the dozens of proteolytic fragments (including those from autolysis of the protease) can be severe, due to high protein molecular weight(s) and the broad isotopic distributions due to multiple deuterations of many peptides. In addition, different subunits of a protein complex can yield isomeric proteolytic fragments. Here, we show that depletion of (13)C and/or (15)N for one or more protein subunits of a complex can greatly simplify the mass spectra, increase the signal-to-noise ratio of the depleted fragment ions, and remove ambiguity in assignment of the m/z values to the correct isomeric peptides. Specifically, it becomes possible to monitor the exchange progress for two isobaric fragments originating from two or more different subunits within the complex, without having to resort to tandem mass spectrometry techniques that can lead to deuterium scrambling in the gas phase. Finally, because the isotopic distribution for a small to medium-size peptide is essentially just the monoisotopic species ((12)C(c)(1)H(h)(14)N(n)(16)O(o)(32)S(s)), it is not necessary to deconvolve the natural abundance distribution for each partially deuterated peptide during HDX data reduction. PMID:20337424

  19. Localized Hydration in Lyophilized Myoglobin by Hydrogen-Deuterium Exchange Mass Spectrometry. 1. Exchange Mapping

    PubMed Central

    Sophocleous, Andreas M.; Zhang, Jun; Topp, Elizabeth M.

    2012-01-01

    The local effects of hydration on myoglobin (Mb) in solid matrices containing mannitol or sucrose (1:1 w/w, protein:additive) were mapped using hydrogen-deuterium exchange with mass spectrometric analysis (HDX-MS) at 5°C and compared to solution controls. Solid powders were exposed to D2O(g) at controlled activity (aw) followed by reconstitution and analysis of the intact protein and peptides produced by pepsin digestion. HDX varied with matrix type, aw, and position along the protein backbone. HDX was less in sucrose matrices than in mannitol matrices at all aw while the difference in solution was negligible. Differences in HDX in the two matrices were detectable despite similarities in their bulk water content. The extent of exchange in solids is proposed as a measure of the hydration of exchangeable amide groups, as well as protein conformation and dynamics; pepsin digestion allows these effects to be mapped with peptide-level resolution. PMID:22352965

  20. Method and source for producing a high concentration of positively charged molecular hydrogen or deuterium ions

    DOEpatents

    Ehlers, Kenneth W. (Alamo, CA); Leung, Ka-Ngo (Hercules, CA)

    1988-01-01

    A high concentration of positive molecular ions of hydrogen or deuterium gas is extracted from a positive ion source having a short path length of extracted ions, relative to the mean free path of the gas molecules, to minimize the production of other ion species by collision between the positive ions and gas molecules. The ion source has arrays of permanent magnets to produce a multi-cusp magnetic field in regions remote from the plasma grid and the electron emitters, for largely confining the plasma to the space therebetween. The ion source has a chamber which is short in length, relative to its transverse dimensions, and the electron emitters are at an even shorter distance from the plasma grid, which contains one or more extraction apertures.

  1. HDXFinder: Automated Analysis and Data Reporting of Deuterium/Hydrogen Exchange Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Miller, Danny E.; Prasannan, Charulata B.; Villar, Maria T.; Fenton, Aron W.; Artigues, Antonio

    2012-02-01

    Hydrogen/deuterium exchange in combination with mass spectrometry (H/D MS) is a sensitive technique for detection of changes in protein conformation and dynamics. However, wide application of H/D MS has been hindered, in part, by the lack of computational tools necessary for efficient analysis of the large data sets associated with this technique. We report a novel web-based application for automatic analysis of H/D MS experimental data. This application relies on the high resolution of mass spectrometers to extract all isotopic envelopes before correlating these envelopes with individual peptides. Although a fully automatic analysis is possible, a variety of graphical tools are included to aid in the verification of correlations and rankings of the isotopic peptide envelopes. As a demonstration, the rate constants for H/D exchange of peptides from rabbit muscle pyruvate kinase are mapped onto the structure of this protein.

  2. Oligomerization Interface of RAGE Receptor Revealed by MS-Monitored Hydrogen Deuterium Exchange

    PubMed Central

    Pozna?ski, Jaros?aw; Kulma, Magdalena; Dadlez, Michal

    2013-01-01

    Activation of the receptor for advanced glycation end products (RAGE) leads to a chronic proinflammatory signal, affecting patients with a variety of diseases. Potentially beneficial modification of RAGE activity requires understanding the signal transduction mechanism at the molecular level. The ligand binding domain is structurally uncoupled from the cytoplasmic domain, suggesting receptor oligomerization is a requirement for receptor activation. In this study, we used hydrogen-deuterium exchange and mass spectrometry to map structural differences between the monomeric and oligomeric forms of RAGE. Our results indicated the presence of a region shielded from exchange in the oligomeric form of RAGE and led to the identification of a new oligomerization interface localized at the linker region between domains C1 and C2. Based on this finding, a model of a RAGE dimer and higher oligomeric state was constructed. PMID:24098480

  3. Determination of hydrogen/deuterium ratio with neutron measurements on MAST

    SciTech Connect

    Klimek, I., E-mail: iwona.klimek@physics.uu.se; Cecconello, M.; Ericsson, G. [Department of Physics and Astronomy, Uppsala University, Uppsala (Sweden); Sharapov, S. E.; Harrison, J. [CCFE, Culham Science Centre, Abingdon (United Kingdom)

    2014-11-15

    On MAST, compressional Alfvén eigenmodes can be destabilized by the presence of a sufficiently large population of energetic particles in the plasma. This dependence was studied in a series of very similar discharges in which increasing amounts of hydrogen were puffed into a deuterium plasma. A simple method to estimate the isotopic ratio n{sub H}/n{sub D} using neutron emission measurements is here described. The inferred isotopic ratio ranged from 0.0 to 0.6 and no experimental indication of changes in radial profile of n{sub H}/n{sub D} were observed. These findings are confirmed by TRANSP/NUBEAM simulations of the neutron emission.

  4. Activation of AMP-activated protein kinase revealed by hydrogen/deuterium exchange mass spectrometry.

    PubMed

    Landgraf, Rachelle R; Goswami, Devrishi; Rajamohan, Francis; Harris, Melissa S; Calabrese, Matthew F; Hoth, Lise R; Magyar, Rachelle; Pascal, Bruce D; Chalmers, Michael J; Busby, Scott A; Kurumbail, Ravi G; Griffin, Patrick R

    2013-11-01

    AMP-activated protein kinase (AMPK) monitors cellular energy, regulates genes involved in ATP synthesis and consumption, and is allosterically activated by nucleotides and synthetic ligands. Analysis of the intact enzyme with hydrogen/deuterium exchange mass spectrometry reveals conformational perturbations of AMPK in response to binding of nucleotides, cyclodextrin, and a synthetic small molecule activator, A769662. Results from this analysis clearly show that binding of AMP leads to conformational changes primarily in the ? subunit of AMPK and subtle changes in the ? and ? subunits. In contrast, A769662 causes profound conformational changes in the glycogen binding module of the ? subunit and in the kinase domain of the ? subunit, suggesting that the molecular binding site of the latter resides between the ? and ? subunits. The distinct short- and long-range perturbations induced upon binding of AMP and A769662 suggest fundamentally different molecular mechanisms for activation of AMPK by these two ligands. PMID:24076403

  5. Time-Resolved Pulsed Hydrogen/Deuterium Exchange Mass Spectrometry Probes Gaseous Proteins Structural Kinetics

    NASA Astrophysics Data System (ADS)

    Rajabi, Khadijeh

    2015-01-01

    A pulsed hydrogen/deuterium exchange (HDX) method has been developed for rapid monitoring of the exchange kinetics of protein ions with D2O a few milliseconds after electrospray ionization (ESI). The stepwise gradual evolution of HDX of multiply charged protein ions was monitored using the pulsed HDX mass spectrometry technique. Upon introducing a very short pulse of D2O (in the ?s to ms time scale) into the linear ion trap (LIT) of a time-of-flight (TOF) mass spectrometer, bimodal distributions were detected for the ions of cytochrome c and ubiquitin. Mechanistic details of HDX reactions for ubiquitin and cytochrome c in the gas phase were uncovered and the structural transitions were followed by analyzing the kinetics of HDX.

  6. [Solid state isotope hydrogen exchange for deuterium and tritium in human gene-engineered insulin].

    PubMed

    2014-01-01

    The reaction of high temperature solid state catalytic isotope exchange in peptides and proteins under the action of catalyst-activated spillover hydrogen was studied. The reaction of human gene-engineered insulin with deuterium and tritium was conducted at 120-140° C to produce insulin samples containing 2-6 hydrogen isotope atoms. To determine the distribution of the isotope label over tritium-labeled insulin's amino acid residues, oxidation of the S-S bonds of insulin by performic acid was performed and polypeptide chains isolated; then their acid hydrolysis, amino acid analysis and liquid scintillation counts of tritium in the amino acids were conducted. The isotope label was shown to be incorporated in all amino acids of the protein, with the peptide fragment FVNQHLCGSHLVE of the insulin ?-chain showing the largest incorporation. About 45% of the total protein isotope label was incorporated in His5 and His10 of this fragment. For the analysis of isotope label distribution in labeled insulin's peptide fragments, the recovery of the S-S bonds by mercaptoethanol, the enzymatic hydrolysis by glutamyl endopeptidase from Bacillus intermedius and HPLC division of the resulting peptides were carried out. Attribution of the peptide fragments formed due to hydrolysis at the Glu-X bond in the ?-chain was accomplished by mass spectrometry. Mass spectrometry analysis data of the deuterium-labeled insulin samples' isotopomeric composition showed that the studied solid state isotope exchange reaction equally involved all the protein molecules. Biological studying of tritium-labeled insulin showed its physiological activity to be completely retained. PMID:25898721

  7. Hydrogen adsorption and storage in carbon nanotubes

    Microsoft Academic Search

    Seung Mi Lee; Ki Soo Park; Young Chul Choi; Young Soo Park; Jin Moon Bok; Dong Jae Bae; Kee Suk Nahm; Yong Gak Choi; Soo Chang Yu; Nam-gyun Kim; Thomas Frauenheim; Young Hee Lee

    2000-01-01

    A comprehensive studies on hydrogen adsorption and storage in carbon nanotubes (CNTs) have been done both experimentally and theoretically. Hydrogen atoms have been stored electrochemically in CNTs. We find that hydrogens exist as a form of H2 molecule in an empty space inside CNTs, which was confirmed by Raman spectra. Several adsorption sites in\\/on CNTs are observed during the discharging

  8. Homogeneous hydrogenation of carbon dioxide

    SciTech Connect

    Jessop, P.G.; Ikariya, Takao; Noyori, Ryoji [Research Development Corp. of Japan, Toyota (Japan). ERATO Molecular Catalysis Project

    1995-03-01

    Carbon dioxide (CO{sub 2}) is of the greatest interest as a C{sub 1} feedstock because of the vast amounts of carbon which exist in this form and because of the low cost of bulk CO{sub 2}. Currently, toxic carbon monoxide, the main competitor for many processes, is used in industry instead because CO{sub 2} is perceived to be less reactive and its efficient catalytic conversion has remained elusive. Because CO{sub 2} is a highly oxidized, thermodynamically stable compound, its utilization requires reaction with certain high energy substances or electroreductive processes. Catalytic hydrogenation is one of the most promising approaches to CO{sub 2} fixation. Recent research has shown that high catalytic efficiency, yields, and rates of reaction can be obtained from CO{sub 2} with optimum conditions and catalysts. This review will describe the simplest and most studied reactions of CO{sub 2}: the catalytic reactions with H{sub 2} in the presence or absence of other reactive species. The mechanisms of homogeneously catalyzed reactions will be emphasized. Subjects which will not be covered, aside from brief mentions, include stoichiometric reactions of CO{sub 2} with complexes, the reverse water gas shift reaction, hydrosilylation, and electrochemical or photochemical reductions of CO{sub 2}. 132 refs.

  9. Effect of hydrogen (deuterium) on properties of fusion power reactor first wall alloys

    Microsoft Academic Search

    N. F. Panayotou; J. K. Tien; R. A. Gross

    1977-01-01

    Candidate first wall fusion reactor materials were subjected to a deuterium bombardment compared to that of anticipated reactors. Significant microstructural and mechanical damage modes were observed. The mechanics involved and the relevance of deuterium interactions to fusion are discussed.

  10. Reactivation of Promoted Nickel Catalysts for Deuterium Exchange between Hydrogen and Water in the Vapour Phase

    Microsoft Academic Search

    F. H. Abou El-Nour

    1980-01-01

    Binary promoted nickel – chromium oxide and ternary promoted nickel – chromium oxide – aluminium oxide mixed catalysts were prepared for use in the present study. The catalysts were prepared by co-precipitation of the corresponding metal nitrates as carbonates followed by calcination in nitrogen atmosphere at 350 °C and reduction in hydrogen atmosphere at 320 °C. To prevent spontaneous oxidation

  11. Measurements and monitoring of the hydrogen and deuterium contents in the plasma of the L-2M stellarator

    NASA Astrophysics Data System (ADS)

    Voronov, G. S.; Berezhetskii, M. S.

    2012-04-01

    The program of experiments on ITER includes a sequential change of the plasma isotopic composition from pure hydrogen plasma in the initial stage of research to deuterium and, then, deuterium-tritium plasma with a gradual increase in the tritium content. In this context, the influence of the plasma isotopic composition on the processes of plasma heating and confinement are being actively studied on the existing tokamaks and stellarators. The plasma isotopic composition also depends on the composition of the gas desorbed from the vacuum chamber wall in the course of recycling. Therefore, the rate of change of the plasma isotopic composition after altering the injected gas also depends on the rate of change of the isotopic composition of the gas absorbed in the wall. These effects were studied in the experiments carried out on the L-2M stellarator in which the working gas was changed from hydrogen to deuterium. Spectral measurements of the intensity ratio between the H ? and D ? lines made it possible to monitor the isotopic composition of the plasma in the course of cleaning of the chamber wall from earlier absorbed hydrogen and its replacement with deuterium. After returning to hydrogen, the rate of cleaning of the wall from deuterium was also determined. The results of these experiments show that the plasma isotopic composition varies exponentially with the number N of shots after transition to another isotope, ˜exp(- N/47). Hence, the isotopic composition can be changed almost completely over 2 to 3 working days. This allows one to study the influence of the plasma isotopic composition on plasma confinement during the same experimental session.

  12. Measurements and monitoring of the hydrogen and deuterium contents in the plasma of the L-2M stellarator

    SciTech Connect

    Voronov, G. S.; Berezhetskii, M. S. [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation)

    2012-04-15

    The program of experiments on ITER includes a sequential change of the plasma isotopic composition from pure hydrogen plasma in the initial stage of research to deuterium and, then, deuterium-tritium plasma with a gradual increase in the tritium content. In this context, the influence of the plasma isotopic composition on the processes of plasma heating and confinement are being actively studied on the existing tokamaks and stellarators. The plasma isotopic composition also depends on the composition of the gas desorbed from the vacuum chamber wall in the course of recycling. Therefore, the rate of change of the plasma isotopic composition after altering the injected gas also depends on the rate of change of the isotopic composition of the gas absorbed in the wall. These effects were studied in the experiments carried out on the L-2M stellarator in which the working gas was changed from hydrogen to deuterium. Spectral measurements of the intensity ratio between the H{sub {alpha}} and D{sub {alpha}} lines made it possible to monitor the isotopic composition of the plasma in the course of cleaning of the chamber wall from earlier absorbed hydrogen and its replacement with deuterium. After returning to hydrogen, the rate of cleaning of the wall from deuterium was also determined. The results of these experiments show that the plasma isotopic composition varies exponentially with the number N of shots after transition to another isotope, {approx}exp(-N/47). Hence, the isotopic composition can be changed almost completely over 2 to 3 working days. This allows one to study the influence of the plasma isotopic composition on plasma confinement during the same experimental session.

  13. ORFEUS II echelle spectra: deuterium and molecular hydrogen in the ISM towards BD +39 3226

    NASA Astrophysics Data System (ADS)

    Bluhm, H.; Marggraf, O.; de Boer, K. S.; Richter, P.; Heber, U.

    1999-12-01

    In ORFEUS II spectra of the sdO star BD +39 3226 interstellar hydrogen and deuterium is detected. >From Ly alpha profile fitting and a curve of growth analysis of the Lyman series of H I and D I we derive the column densities N_H = 1.20+0.28}-0.22}{*10{20 cm-2 and N_D = 1.45+0.50}-0.38}{*10{15 cm-2. >From the analysis of metal absorption lines in ORFEUS and IUE spectra we obtain column densities for 11 elements. In addition, we examine absorption lines of H_2 for rotational excitation states up to J=7. We find an H_2 ortho-to-para ratio of 2.5, the fractional abundance of molecular hydrogen has a low value of log f=-4.08 for a total amount of N(H_2)=4.8+2.0}-1.6}{*10{15cm- 2. The column densities of the excitation states reveal a moderate Boltzmann excitation temperature of 130 K and an equivalent excitation temperature for the excited upper states due to UV pumping of <1800 K. Based on data obtained under the DARA ORFEUS guest observer programme

  14. Electrochemical reduction of disulfide-containing proteins for hydrogen/deuterium exchange monitored by mass spectrometry.

    PubMed

    Mysling, Simon; Salbo, Rune; Ploug, Michael; Jørgensen, Thomas J D

    2014-01-01

    Characterization of disulfide bond-containing proteins by hydrogen/deuterium exchange monitored by mass spectrometry (HDX-MS) requires reduction of the disulfide bonds under acidic and cold conditions, where the amide hydrogen exchange reaction is quenched (pH 2.5, 0 °C). The reduction typically requires a high concentration (>200 mM) of the chemical reducing agent Tris(2-carboxyethyl)phosphine (TCEP) as its reduction rate constant is decreased at low pH and temperature. Serious adverse effects on chromatographic and mass spectrometric performances have been reported when using high concentrations of TCEP. In the present study, we explore the feasibility of using electrochemical reduction as a substitute for TCEP in HDX-MS analyses. Our results demonstrate that efficient disulfide bond reduction is readily achieved by implementing an electrochemical cell into the HDX-MS workflow. We also identify some challenges in using electrochemical reduction in HDX-MS analyses and provide possible conditions to attenuate these limitations. For example, high salt concentrations hamper disulfide bond reduction, necessitating additional dilution of the sample with aqueous acidic solution at quench conditions. PMID:24251601

  15. Platform dependencies in bottom-up hydrogen/deuterium exchange mass spectrometry.

    PubMed

    Burns, Kyle M; Rey, Martial; Baker, Charles A H; Schriemer, David C

    2013-02-01

    Hydrogen-deuterium exchange mass spectrometry is an important method for protein structure-function analysis. The bottom-up approach uses protein digestion to localize deuteration to higher resolution, and the essential measurement involves centroid mass determinations on a very large set of peptides. In the course of evaluating systems for various projects, we established two (HDX-MS) platforms that consisted of a FT-MS and a high-resolution QTOF mass spectrometer, each with matched front-end fluidic systems. Digests of proteins spanning a 20-110 kDa range were deuterated to equilibrium, and figures-of-merit for a typical bottom-up (HDX-MS) experiment were compared for each platform. The Orbitrap Velos identified 64% more peptides than the 5600 QTOF, with a 42% overlap between the two systems, independent of protein size. Precision in deuterium measurements using the Orbitrap marginally exceeded that of the QTOF, depending on the Orbitrap resolution setting. However, the unique nature of FT-MS data generates situations where deuteration measurements can be inaccurate, because of destructive interference arising from mismatches in elemental mass defects. This is shown through the analysis of the peptides common to both platforms, where deuteration values can be as low as 35% of the expected values, depending on FT-MS resolution, peptide length and charge state. These findings are supported by simulations of Orbitrap transients, and highlight that caution should be exercised in deriving centroid mass values from FT transients that do not support baseline separation of the full isotopic composition. PMID:23197788

  16. Microsecond pulsed hydrogen/deuterium exchange of electrosprayed ubiquitin ions stored in a linear ion trap.

    PubMed

    Rajabi, Khadijeh

    2015-02-01

    A pulse of D2O vapour on the order of microseconds is allowed to react with the +6 to +9 charge states of ubiquitin confined in a linear ion trap (LIT). Two envelopes of peaks are detected for the ions of ubiquitin, corresponding to the ions that exchange more quickly and more slowly. The deuterium uptake of the protonated sites on ubiquitin ions accounts for the ion population with the fast exchange. The hydrogen/deuterium exchange (HDX) kinetics of ubiquitin ions trapped in the LIT for 200 ms showed comparable structural transitions to those trapped for 300 ms. When ions are trapped for longer, i.e. up to 2000 ms, mainly the slow exchanging ion population is detected. In all experiments the +7 ions exchange the most, suggesting a short distance between the surface protonated sites and nearby charged sites, and concomitantly high accessibility of surface protonated sites towards D2O. The +6 ions are more compact than the +7 ions but have one fewer protonated site, therefore fewer surface availabilities for D2O attack. The data suggest that the +6 ions keep most of their solution-phase contacts intact while the hydrophobic core is slightly interrupted in the +7 ions, possibly due to the exposure of charged His68 that is normally buried in the hydrophobic pocket. The +8 and +9 ions have more protonated sites but are less compact than the +7 ions because of Coulombic repulsion, resulting in a larger distance between the protonated sites and the basic sites. The data indicate that the HDX mechanism of ions with the slower exchange corresponding to the second envelope of peaks is primarily governed via a relay mechanism. The results suggest that the pulsed HDX MS method is sampling a population of ubiquitin ions with a similar backbone fold to the solution. PMID:25553956

  17. Carbon-hydrogen bonding in near-frictionless carbon.

    SciTech Connect

    Johnson, J. A.; Woodford, J. B.; Rajput, D.; Kolesnikov, A. I.; Schleuter, J. A.; Eryilmaz, O. L.; Erdemir, A.; Univ. of Tennessee Space Inst.; ORNL

    2008-01-01

    The uniquely low friction behavior of near-frictionless carbon (NFC) as compared to conventional diamondlike carbon (DLC) is determined by the bonding within the film. Inelastic neutron scattering (INS) and Fourier transform infrared (FTIR) spectroscopy were used to probe the bonding environment of carbon and hydrogen; both INS and FTIR can probe the whole sample. Previous work has focused on surface studies; the present results show that in the film as a whole the majority of the hydrogen is adjacent to sp{sup 3}-bonded carbon. In addition this work has determined the absence of any molecular hydrogen in NFC.

  18. Carbon-hydrogen bonding in near-frictionless carbon

    NASA Astrophysics Data System (ADS)

    Johnson, J. A.; Woodford, J. B.; Rajput, D.; Kolesnikov, A. I.; Schleuter, J. A.; Eryilmaz, O. L.; Erdemir, A.

    2008-09-01

    The uniquely low friction behavior of near-frictionless carbon (NFC) as compared to conventional diamondlike carbon (DLC) is determined by the bonding within the film. Inelastic neutron scattering (INS) and Fourier transform infrared (FTIR) spectroscopy were used to probe the bonding environment of carbon and hydrogen; both INS and FTIR can probe the whole sample. Previous work has focused on surface studies; the present results show that in the film as a whole the majority of the hydrogen is adjacent to sp3-bonded carbon. In addition this work has determined the absence of any molecular hydrogen in NFC.

  19. Carbon-hydrogen bonding in near-frictionless carbon

    SciTech Connect

    Johnson, Jackie A. [University of Tennessee Space Institute; Woodford, John B [Argonne National Laboratory (ANL); Rajput, Deepak [University of Tennessee Space Institute; Kolesnikov, Alexander I [ORNL; Schleuter, John A [Argonne National Laboratory (ANL); Eryilmaz, Osman L [Argonne National Laboratory (ANL); Erdemir, Ali [Argonne National Laboratory (ANL)

    2008-01-01

    The uniquely low friction behavior of near frictionless carbon (NFC) as compared to conventional diamond-like carbon (DLC) is determined by the bonding within the film. Inelastic neutron scattering (INS) and Fourier Transform Infrared (FTIR) spectroscopy were used to probe the bonding environment of carbon and hydrogen; both INS and FTIR can probe the whole sample. Previous work has focused on surface studies; the present results show that in the film as a whole the majority of the hydrogen is adjacent to sp3-bonded carbon. In addition this work has determined the absence of any molecular hydrogen in NFC.

  20. Carbon and hydrogen isotopic composition of bacterial methane in a shallow freshwater lake

    SciTech Connect

    Woltemate, I.; Whiticar, M.J.; Schoell, M.

    1984-09-01

    Anoxic sediments from freshwater environments such as bogs, swamps, and lakes undergoing early diagenesis are frequently characterized by the formation of biogenic methane. Freshwater biogenic methanes exhibit carbon and hydrogen isotopic values strongly depleted in C-13 and deuterium relative to the respective values for carbon dioxide and formation water. The percentages of methane generated by fermentation and carbon dioxide reduction can be estimated by comparison of hydrogen isotopes in the formation water and methane. On the basis of these hydrogen isotope data, about 75% of the methane formation in Wurmsee comes from acetate reduction. Fermentation is thus the dominant although not exclusive process. Carbon dioxide reduction contributed the balance of the bacterial methane generated. 35 references, 5 figures, 1 table.

  1. Substrate binding and conformational changes of Clostridium glutamicum diaminopimelate dehydrogenase revealed by hydrogen/deuterium exchange and electrospray mass spectrometry.

    PubMed Central

    Wang, F.; Scapin, G.; Blanchard, J. S.; Angeletti, R. H.

    1998-01-01

    C. glutamicum meso-diaminopimelate dehydrogenase is an enzyme of the L-lysine biosynthetic pathway in bacteria. The binding of NADPH and diaminopimelate to the recombinant, overexpressed enzyme has been analyzed using hydrogen/deuterium exchange and electrospray ionization/mass spectrometry. NADPH binding reduces the extent of deuterium exchange, as does the binding of diaminopimelate. Pepsin digestion of the deuterated enzyme and enzyme-substrate complexes coupled with liquid chromatography/mass spectrometry have allowed the identification of eight peptides whose deuterium exchange slows considerably upon the binding of the substrates. These peptides represent regions known or thought to bind NADPH and diaminopimelate. One of these peptides is located at the interdomain hinge region and is proposed to be exchangeable in the "open," catalytically inactive, conformation but nonexchangeable in the "closed," catalytically active conformation formed after NADPH and diaminopimelate binding and domain closure. Furthermore, the dimerization region has been localized by this method, and this study provides an example of detecting protein-protein interface regions using hydrogen/deuterium exchange and electrospray ionization. PMID:9521104

  2. Designing Microporus Carbons for Hydrogen Storage Systems

    SciTech Connect

    Alan C. Cooper

    2012-05-02

    An efficient, cost-effective hydrogen storage system is a key enabling technology for the widespread introduction of hydrogen fuel cells to the domestic marketplace. Air Products, an industry leader in hydrogen energy products and systems, recognized this need and responded to the DOE 'Grand Challenge' solicitation (DOE Solicitation DE-PS36-03GO93013) under Category 1 as an industry partner and steering committee member with the National Renewable Energy Laboratory (NREL) in their proposal for a center-of-excellence on Carbon-Based Hydrogen Storage Materials. This center was later renamed the Hydrogen Sorption Center of Excellence (HSCoE). Our proposal, entitled 'Designing Microporous Carbons for Hydrogen Storage Systems,' envisioned a highly synergistic 5-year program with NREL and other national laboratory and university partners.

  3. Deuterium isotope effects and fractionation factors of hydrogen-bonded A:T base pairs of DNA.

    PubMed

    Vakonakis, Ioannis; Salazar, Miguel; Kang, Mijeong; Dunbar, Kim R; LiWang, Andy C

    2003-02-01

    Deuterium isotope effects and fractionation factors of N1.H3-N3 hydrogen bonded Watson-Crick A:T base pairs of two DNA dodecamers are presented here. Specifically, two-bond deuterium isotope effects on the chemical shifts of (13)C2 and (13)C4, (2)delta(13)C2 and (2)delta(13)C4, and equilibrium deuterium/protium fractionation factors of H3, Phi, were measured and seen to correlate with the chemical shift of the corresponding imino proton, delta(H3). Downfield-shifted imino protons associated with larger values of (2)delta(13)C2 and (2)delta(13)C4 and smaller Phi values, which together suggested that the effective H3-N3 vibrational potentials were more anharmonic in the stronger hydrogen bonds of these DNA molecules. We anticipate that (2)delta(13)C2, (2)delta(13)C4 and Phi values can be useful gauges of hydrogen bond strength of A:T base pairs. PMID:12652119

  4. Photobiological hydrogen production and carbon dioxide sequestration

    Microsoft Academic Search

    Halil Berberoglu

    2008-01-01

    Photobiological hydrogen production is an alternative to thermochemical and electrolytic technologies with the advantage of carbon dioxide sequestration. However, it suffers from low solar to hydrogen energy conversion efficiency due to limited light transfer, mass transfer, and nutrient medium composition. The present study aims at addressing these limitations and can be divided in three parts: (1) experimental measurements of the

  5. Localized hydration in lyophilized myoglobin by hydrogen-deuterium exchange mass spectrometry. 1. Exchange mapping.

    PubMed

    Sophocleous, Andreas M; Zhang, Jun; Topp, Elizabeth M

    2012-04-01

    The local effects of hydration on myoglobin (Mb) in solid matrices containing mannitol or sucrose (1:1 w/w, protein:additive) were mapped using hydrogen-deuterium exchange with mass spectrometric analysis (HDX-MS) at 5 °C and compared to solution controls. Solid powders were exposed to D?O(g) at controlled activity (a(w)) followed by reconstitution and analysis of the intact protein and peptides produced by pepsin digestion. HDX varied with matrix type, a(w), and position along the protein backbone. HDX was less in sucrose matrices than in mannitol matrices at all a(w) while the difference in solution was negligible. Differences in HDX in the two matrices were detectable despite similarities in their bulk water content. The extent of exchange in solids is proposed as a measure of the hydration of exchangeable amide groups, as well as protein conformation and dynamics; pepsin digestion allows these effects to be mapped with peptide-level resolution. PMID:22352965

  6. Differential hydrogen/deuterium exchange mass spectrometry analysis of protein-ligand interactions.

    PubMed

    Chalmers, Michael J; Busby, Scott A; Pascal, Bruce D; West, Graham M; Griffin, Patrick R

    2011-02-01

    Functional regulation of ligand-activated receptors is driven by alterations in the conformational dynamics of the protein upon ligand binding. Differential hydrogen/deuterium exchange (HDX) coupled with mass spectrometry has emerged as a rapid and sensitive approach for characterization of perturbations in conformational dynamics of proteins following ligand binding. While this technique is sensitive to detecting ligand interactions and alterations in receptor dynamics, it also can provide important mechanistic insights into ligand regulation. For example, HDX has been used to determine a novel mechanism of ligand activation of the nuclear receptor peroxisome proliferator activated receptor-?, perform detailed analyses of binding modes of ligands within the ligand-binding pocket of two estrogen receptor isoforms, providing insight into selectivity, and helped classify different types of estrogen receptor-? ligands by correlating their pharmacology with the way they interact with the receptor based solely on hierarchical clustering of receptor HDX signatures. Beyond small-molecule-receptor interactions, this technique has also been applied to study protein-protein complexes, such as mapping antibody-antigen interactions. In this article, we summarize the current state of the differential HDX approaches and the future outlook. We summarize how HDX analysis of protein-ligand interactions has had an impact on biology and drug discovery. PMID:21329427

  7. Differential hydrogen/deuterium exchange mass spectrometry analysis of protein–ligand interactions

    PubMed Central

    Chalmers, Michael J; Busby, Scott A; Pascal, Bruce D; West, Graham M; Griffin, Patrick R

    2011-01-01

    Functional regulation of ligand-activated receptors is driven by alterations in the conformational dynamics of the protein upon ligand binding. Differential hydrogen/deuterium exchange (HDX) coupled with mass spectrometry has emerged as a rapid and sensitive approach for characterization of perturbations in conformational dynamics of proteins following ligand binding. While this technique is sensitive to detecting ligand interactions and alterations in receptor dynamics, it also can provide important mechanistic insights into ligand regulation. For example, HDX has been used to determine a novel mechanism of ligand activation of the nuclear receptor peroxisome proliferator activated receptor-?, perform detailed analyses of binding modes of ligands within the ligand-binding pocket of two estrogen receptor isoforms, providing insight into selectivity, and helped classify different types of estrogen receptor-? ligands by correlating their pharmacology with the way they interact with the receptor based solely on hierarchical clustering of receptor HDX signatures. Beyond small-molecule–receptor interactions, this technique has also been applied to study protein–protein complexes, such as mapping antibody–antigen interactions. In this article, we summarize the current state of the differential HDX approaches and the future outlook. We summarize how HDX analysis of protein–ligand interactions has had an impact on biology and drug discovery. PMID:21329427

  8. Elastic and Transport Cross Sections for Argon and Carbon in Hydrogen Plasmas

    NASA Astrophysics Data System (ADS)

    Schultz, David; Krstic?, Predrag

    2002-11-01

    The elastic transport processes of argon and carbon in the hydrogen plasma is of fundamental importance in a variety of plasma environments. Thus, hydrogen argon-mixtures are utilized in plasma processing and in low pressure discharges. Argon is also useful as an impurity ion tracer in a magnetic fusion plasmas. On the other hand, interest in the carbon transport stems from the ubiquity of graphite used as a plasma facing material in many present and planned fusion devices. By utilizing the fully quantum approach, we have calculated accurate elastic differential and integral scattering cross sections as well as the transport coefficients for hydrogen (deuterium, tritium) ions colliding with argon and carbon in the center of mass energy 0.1-100 eV. Momentum transfer and viscosity were extended to higher collision energies (up to 10 keV) using classical methods. Results were compared with previously recommended values.

  9. Desorption of hydrogen trapped in carbon and graphite

    NASA Astrophysics Data System (ADS)

    Atsumi, H.; Takemura, Y.; Miyabe, T.; Konishi, T.; Tanabe, T.; Shikama, T.

    2013-11-01

    Thermal desorption behavior of deuterium (D2) from isotropic graphites and a carbon fiber carbon composite (CFC) charged with D2 gas has been investigated to obtain information concerning hydrogen recycling and tritium inventory in fusion experimental devices as well as a futuristic fusion reactor. After thermal desorption experiments were conducted at temperatures up to 1740 K, a desorption peak at approximately 1600 K (peak 4) was discovered. This is in addition to the previously known peak at approximately 1300 K (peak 3). Peak 3 can be attributed to the release of deuterium controlled by the diffusion process in a graphite filler grain and peak 4 can be attributed to the detrapping of deuterium released from an interstitial cluster loop edge site. Activation energies of peaks 3 and 4 are estimated to be 3.48 and 6.93 eV, respectively. TDS spectra of D2 from graphite and CFCs had previously not been thoroughly investigated. A desorption peak at approximately 1600 K was discovered in the TDS spectra for all samples heated with a linear ramp rate of 0.1 K/s. For an isotropic graphite, ISO-880U, four desorption peaks were recognized in the TDS spectra at approximately 660 K, 900 K, 1300 K, and 1600 K. These peaks were named as peaks 1, 2, 3, and 4 in order of increasing temperature. Major desorption peaks (i.e., peaks 3 and 4) were analyzed and discussed in detail. The temperature of peak 3 was dependent on the size of a graphite filler grain. The desorption process is suggested to be controlled by deuterium diffusion within the filler grain with a strong influence of trapping sites, where the migration takes place as a sequence of detrapping and retrapping. The desorption for peak 4 can be ascribed to the detrapping reaction from an interstitial cluster loop edge site. Activation energies were estimated from the peak shift by varying the heating rate of TDS to be 3.48 and 6.93 eV for peaks 3 and 4, respectively. Theoretical desorption curves for peaks 3 and 4 with the above mentioned activation energies were narrower than those for the experimental desorption curve. The observed peak broadening can be attributed to the effects of grain size and activation energy distributions.

  10. Automated Hydrogen/Deuterium Exchange Electron Transfer Dissociation High Resolution Mass Spectrometry Measured at Single-Amide Resolution

    NASA Astrophysics Data System (ADS)

    Landgraf, Rachelle R.; Chalmers, Michael J.; Griffin, Patrick R.

    2012-02-01

    Hydrogen deuterium exchange mass spectrometry (HDX-MS) is a well established method for the measurement of solution-phase deuterium incorporation into proteins, which can provide insight into protein conformational mobility. However, most HDX measurements are constrained to regions of the protein where pepsin proteolysis allows detection at peptide resolution. Recently, single-amide resolution deuterium incorporation has been achieved by limiting gas-phase scrambling in the mass spectrometer. This was accomplished by employing a combination of soft ionization and desolvation conditions coupled with the radical-driven fragmentation technique electron transfer dissociation (ETD). Here, a hybrid LTQ-Orbitrap XL is systematically evaluated for its utility in providing single-amide deuterium incorporation for differential HDX analysis of a nuclear receptor upon binding small molecule ligands. We are able to show that instrumental parameters can be optimized to minimize scrambling and can be incorporated into an established and fully automated HDX platform making differential single-amide HDX possible for bottom-up analysis of complex systems. We have applied this system to determine differential single amide resolution HDX data for the peroxizome proliferator activated receptor bound with two ligands of interest.

  11. High-Resolution Mass Spectrum for Deuterium (hydrogen) Gas Permeating Palladium Film

    NASA Astrophysics Data System (ADS)

    Wei, Qing M.; Li, Xing Z.; Liu, Bin; Mueller, N.; Schoch, P.; Oehre, H.

    High-resolution mass spectrometer was used to analyze the gas from a deuterium flux maker. Mass 3 components were analyzed carefully to inspect any anomaly from the deuterium gas permeating a palladium film. Mass 3 component is confirmed again, but more work is needed to separate the signal of the helium-3 (if any) from the heavy background of D-T molecules.

  12. Titanium Doped Carbon Nanotubes for Hydrogen Storage

    NASA Astrophysics Data System (ADS)

    Fennick, Jake; Lewis, James

    2008-03-01

    An efficient method of storing hydrogen is necessary before fuel cells can become practical. Previous computational results show that a single titanium atom adsorbed on the surface of a carbon nanotube can bind up to 4 hydrogen molecules. We pursue simulations of hydrogen packed between two titanium-doped carbon nanotubes. The highest percentage weight of storage and the manner in which these parallel nanotubes pack is of particular interest. Calculations are performed with the classical MD program GULP. After computation, automated analysis will choose the combination of parameters that results in the most efficient hydrogen storage for these titanium-doped carbon nanotube systems. [1] Yildrim, T.; Ciraci, S. Phys. ReV. Lett. 2005, 94, 175501.

  13. Homogeneous hydrogenation of carbon dioxide

    Microsoft Academic Search

    Philip G. Jessop; Takao. Ikariya; Ryoji. Noyori

    1995-01-01

    Carbon dioxide (COâ) is of the greatest interest as a C⁠feedstock because of the vast amounts of carbon which exist in this form and because of the low cost of bulk COâ. Currently, toxic carbon monoxide, the main competitor for many processes, is used in industry instead because COâ is perceived to be less reactive and its efficient catalytic

  14. Hydrogenation of anthracene over active carbon-supported nickel catalyst

    Microsoft Academic Search

    Z.-G Zhang; K Okada; M Yamamoto; T Yoshida

    1998-01-01

    Hydrogen transfer behavior over active carbon and carbon-supported Ni catalyst was examined in the hydrogenation of anthracene with three kinds of hydrogen sources: hydrogen gas, hydrogen-donor tetralin and the combination of both. In tetralin, active carbon itself provided higher conversions of anthracene in the temperature range of 350–400°C than Ni\\/C catalyst, while under the pressure of hydrogen gas, the addition

  15. Structural Insights of Glucan Phosphatase Dynamics using Amide Hydrogen/Deuterium Exchange Mass Spectrometry

    PubMed Central

    Hsu, Simon; Kim, Youngjun; Li, Sheng; Durrant, Eric S.; Pace, Rachel M.; Woods, Virgil L.; Gentry, Matthew S.

    2009-01-01

    Laforin and Starch Excess 4 (SEX4) are founding members of a class of phosphatases that dephosphorylate phosphoglucans. Each protein contains a carbohydrate binding module (CBM) and a dual specificity phosphatase (DSP) domain. The gene encoding laforin is mutated in a fatal neurodegenerative disease called Lafora disease (LD). In the absence of laforin function, insoluble glucans accumulate that are hyperphosphorylated and exhibit sparse branching. It is hypothesized that these accumulations trigger the neurodegeneration and premature death of LD patients. We recently demonstrated that laforin removes phosphate from phosphoglucans and hypothesized that this function inhibits insoluble glucan accumulation. Loss of SEX4 function in plants yields a similar cellular phenotype; cells accumulate an excess amount of insoluble, hyperphosphorylated glucans. While multiple groups have shown that these phosphatases dephosphorylate phosphoglucans, there is no structure of a glucan phosphatase and little is known about the mechanism whereby they perform this action. We utilized hydrogen-deuterium exchange mass spectrometry (DXMS) and structural modeling to probe the conformational and structural dynamics of the glucan phosphatase SEX4. We found that the enzyme does not undergo a global conformational change upon glucan binding, but instead undergoes minimal rearrangement upon binding. The CBM undergoes increased protection from deuteration when bound to glucans, confirming its role in glucan binding. More interestingly, we identified structural components of the DSP that also undergo increased protection from deuteration upon glucan addition. To determine the position of these regions, we generated a homology model of the SEX4 DSP. The homology model shows that all of these regions are adjacent the DSP active site. Therefore, our results suggest that these regions of the DSP participate in presenting the phosphoglucan to the active site and provide the first structural analysis and mode of action of this unique class of phosphatases. PMID:19754155

  16. Amide hydrogen/deuterium exchange & MALDI-TOF mass spectrometry analysis of Pak2 activation.

    PubMed

    Hsu, Yuan-Hao; Traugh, Jolinda A

    2011-01-01

    Amide hydrogen/deuterium exchange (H/D exchange) coupled with mass spectrometry has been widely used to analyze the interface of protein-protein interactions, protein conformational changes, protein dynamics and protein-ligand interactions. H/D exchange on the backbone amide positions has been utilized to measure the deuteration rates of the micro-regions in a protein by mass spectrometry(1,2,3). The resolution of this method depends on pepsin digestion of the deuterated protein of interest into peptides that normally range from 3-20 residues. Although the resolution of H/D exchange measured by mass spectrometry is lower than the single residue resolution measured by the Heteronuclear Single Quantum Coherence (HSQC) method of NMR, the mass spectrometry measurement in H/D exchange is not restricted by the size of the protein(4). H/D exchange is carried out in an aqueous solution which maintains protein conformation. We provide a method that utilizes the MALDI-TOF for detection(2), instead of a HPLC/ESI (electrospray ionization)-MS system(5,6). The MALDI-TOF provides accurate mass intensity data for the peptides of the digested protein, in this case protein kinase Pak2 (also called ?-Pak). Proteolysis of Pak 2 is carried out in an offline pepsin digestion. This alternative method, when the user does not have access to a HPLC and pepsin column connected to mass spectrometry, or when the pepsin column on HPLC does not result in an optimal digestion map, for example, the heavily disulfide-bonded secreted Phospholipase A(2;) (sPLA(2;)). Utilizing this method, we successfully monitored changes in the deuteration level during activation of Pak2 by caspase 3 cleavage and autophosphorylation(7,8,9). PMID:22143461

  17. Gas phase recombination of hydrogen and deuterium atoms. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Trainor, D. W.; Ham, D. O.; Kaufman, F.

    1973-01-01

    Rate constants for the reaction H + H + M - H2 + M, with M = H2, He, and Ar were measured over the temperature range 77 to 298 K. Hydrogen atoms were produced by thermal dissociation and absolute atom concentrations were measured through use of self-balancing, isothermal catalytic probe detector. The specific rate constants were 8.1 + or - 0.4 x 10 to the minus 33rd power, 7.0 + or - 0.4 x 10 to the minus 33rd power, and 9.2 + or - 0.6 x at 298 K for M = H2, He, and Ar respectively; these values rising to 18.5 + or - 2.2 x 10 to the minus 33rd power, 12.0 + or - 1.5 x 10 to the minus 33rd power, and 27.4 + or - 4.6 x 10 to the minus 33rd power cm to the 6th power/molecules sq/sec at 77 K. for the equivalent deuterium atom process with D2 as the third body, the rate constants are 6.1 + or - 0.3 x 10 to the minus 33rd power cm to the 6th power/molecules sq/sec at 298 K and 15.1 + or - 1.0 x 10 to the minus 33rd power cm to the 6th power/molecules sq/sec at 77 K. These values are compared with previous experimental measurements and with recent theoretical calculations.

  18. Effects of protein-ligand interactions on hydrogen/deuterium exchange kinetics: canonical and noncanonical scenarios.

    PubMed

    Sowole, Modupeola A; Konermann, Lars

    2014-07-01

    Hydrogen/deuterium exchange (HDX) methods are widely used for monitoring protein-ligand interactions. This approach relies on the fact that ligand binding can modulate the extent of protein structural fluctuations that transiently disrupt hydrogen bonds and expose backbone amides to the solvent. It is commonly observed that ligand binding causes a reduction of HDX rates. This reduction can be restricted to elements adjacent to the binding site, but other regions can be affected as well. Qualitatively, ligand-induced HDX protection can be rationalized on the basis of two-state models that equate structural dynamics with global unfolding/refolding. Unfortunately, such models tend to be unrealistic because the dynamics of native proteins are dominated by subglobal transitions and local fluctuations. Ligand binding lowers the ground-state free energy. It is not obvious why this should necessarily be accompanied by a depletion of excited-state occupancies, which would be required for a reduction of HDX rates. Here, we propose a framework that implies that ligand binding can either slow or accelerate amide deuteration throughout the protein. These scenarios are referred to as "type 1" and "type 2", respectively. Evidence for type 1 binding is abundant in the literature, whereas the viability of type 2 interactions is less clear. Using HDX mass spectrometry (MS), we demonstrate that the oxygenation of hemoglobin (Hb) provides a dramatic example of a type 2 scenario. The observed behavior is consistent with cooperative T ? R switching, where part of the intrinsic O2 binding energy is reinvested for destabilization of the ground state. This destabilization increases the Boltzmann occupancy of unfolded conformers, thereby enhancing HDX rates. Surprisingly, O2 binding to myoglobin (Mb) also induces elevated HDX rates. These Mb data reveal that type 2 behavior is not limited to cooperative multisubunit systems. Although enhanced protection from deuteration is widely considered to be a hallmark of protein-ligand interactions, this work establishes that an overall deuteration increase also represents a viable outcome. HDX-based ligand screening assays, therefore, have to allow for canonical as well as noncanonical effects. PMID:24904985

  19. Microstructural studies of hydrogen and deuterium in bcc refractory metals. Progress report, 1 May 1979-31 July 1980

    SciTech Connect

    Moss, S.C.

    1980-01-01

    Over the past four years this research has been principally concerned with uncovering the microstructural atomic arrangements in alloys of hydrogen and deuterium with bcc refractory metals. Because these are interstitial phases in which the host metal lattice is substantially deformed by the incorporation of the H(D) atoms, there are pronounced x-ray scattering effects. X-ray diffraction has, therefore, been the main structural tool. A main objective of the project has been to determine the degree to which phase relations and solid solution properties in metal-hydride alloys depend upon the hydrogen-hydrogen interaction via the displacement field of the metal atoms. This has often included the elucidation of subtle thermodynamic properties which are revealed in structural studies.

  20. Structure and function of circadian clock proteins and deuterium isotope effects in nucleic acid hydrogen bonds 

    E-print Network

    Vakonakis, Ioannis

    2005-08-29

    in solution, and a correlation was established between decreasing fractionation factors and increasing imino proton chemical shift, ?H3. Similarly, a correlation was observed between ?H3and deuterium isotope effects (DIE) on chemical shift...

  1. Equilibrium carbon and hydrogen isotope fractionation in iron

    NASA Astrophysics Data System (ADS)

    Schauble, E. A.

    2009-12-01

    Recent theoretical and experimental studies (e.g., [1-3]) have suggested that Si- and Fe-isotopic signatures can be used to characterize the compositions and conditions of segregation of metallic cores in planetary interiors. This study expands the theoretical framework to include carbon and hydrogen, which may also be alloying elements. Hydrogen (D/H) and carbon (13C/12C) fractionations in iron-rich metallic melts are estimated by modeling analogous iron-rich crystals, i.e., dhcp-FeH and ?-Fe2C. C- and H-atoms in these crystals are completely coordinated by iron. The driving energy for equilibrium fractionation is assumed to come from the reduction of vibrational frequencies when heavy isotopes are substituted for light ones; vibrations are assumed to be harmonic. This treatment is crude at high temperature, and for the relatively anharmonic vibrations typical of hydrogen-bearing substances, but may provide a reasonably accurate, semi-quantitative approximation of real fractionation behavior. Vibrational frequencies of all crystals are modeled with density functional theory, using gradient-corrected functionals and ultrasoft pseudopotentials. For both carbon and hydrogen, the models suggest that the metal phase will be strongly depleted in heavy isotopes. At 2000 K, 1 atm, ?-Fe2C will have 3‰ lower 13C/12C than coexisting diamond. Combining this result with previous high-temperature theoretical and experimental studies (e.g., [4]), metal-graphite fractionation is expected to be very similar, while metal-CO2 fractionation will be almost twice as large, ca. -5‰. Deuterium/hydrogen fractionations are expected to be an order of magnitude larger, with 50-70‰ lower D/H in dhcp-FeH than in coexisting H2 gas at 2000 K, and approximately 100‰ lower D/H than water vapor. These fractionations are much larger than those inferred for silicon and iron, as expected given the differences in atomic mass. References: 1. Georg et al. (2007) Nature 447:1102; 2. Rustad & Yin (2009) Nature Geoscience doi:10.1038/ngeo546; 3. Polyakov (2009) Science 323:912; 4. Polyakov & Kharlashina (1995) GCA 59:2561.

  2. Exclusive Photoproduction of Charged Pions in Hydrogen and Deuterium from 1 to 6 GeV

    SciTech Connect

    Lingyan Zhu

    2004-02-28

    The study of the transition region in the description of exclusive processes and hadron structure, from the nucleon-meson degrees of freedom in meson-exchange models at low energy to the quark-gluon degrees of freedom in pQCD at high energy, is essential for us to understand the strong interaction. The differential cross section measurements for exclusive reactions at fixed center-of-mass angles enable us to investigate the constituent counting rule, which explicitly connects the quark-gluon degrees of freedom to the energy dependence of differential cross sections. JLab Experiment E94-104 was carried out in Hall A with two high resolution spectrometers. It included the coincidence cross section measurement for the [gamma]n --> pi{sup -}[p] process with a deuterium target and the singles measurement for the [gamma]p --> pi{sup +}[n] process with a hydrogen target. The untagged real photons were generated by the electron beam impinging on a copper radiator. The photon energies ranged from 1.1 to 5.5 GeV, corresponding to the center-of-mass energies from 1.7 to 3.4 GeV. The pion center-of-mass angles were fixed at 50 deg, 70 deg, 90 deg, and also 100 deg, 110 deg at a few energies. The JLab E94-104 data presented in this thesis contain four interesting features. The data exhibit a global scaling behavior for both [pi]{sup -} and [pi]{sup +} photoproduction at high energies and high transverse momenta, consistent with the constituent counting rule and the existing [pi]{sup +} photoproduction data. This implies that the quark-gluon degrees of freedom start to play a role at this energy scale. The data suggests possible substructure of the scaling behavior, which might be oscillations around the scaling value. There are several possible mechanisms that can cause oscillations, for example the one associated with the generalized constituent counting rule involving quark orbital angular momentum. The data show an enhancement in the scaled cross section at center-of-mass energy near 2.2 GeV, where baryon resonances are not as well known as those at low energies. The differential cross section ratios for exclusive [gamma]n --> pi{sup -}[p] to [gamma]p --> pi{sup +}[n] process at [theta]{sub cm} = 90 deg start to show consistency with the prediction based on one-hard-gluon-exchange diagrams at high energies.

  3. Resolving Isotopic Fine Structure to Detect and Quantify Natural Abundance- and Hydrogen/Deuterium Exchange-Derived Isotopomers

    PubMed Central

    Liu, Qian; Easterling, Michael L.; Agar, Jeffrey N.

    2014-01-01

    Hydrogen/deuterium exchange (HDX) mass spectrometry (MS) is used for analyzing protein dynamics, protein folding/unfolding, and molecular interactions. Until this study, HDX MS experiments employed mass spectral resolving powers that afforded only one peak per nominal mass in a given peptide’s isotope distribution, and HDX MS data analysis methods were developed accordingly. A level of complexity that is inherent to HDX MS remained unaddressed, namely, various combinations of natural abundance heavy isotopes and exchanged deuterium shared the same nominal mass and overlapped at previous resolving powers. For example, an A + 2 peak is comprised of (among other isotopomers) a two-2H-exchanged/zero-13C isotopomer, a one-2H-exchanged/one-13C isotopomer, and a zero-2H-exchanged/two-13C isotopomer. Notably, such isotopomers differ slightly in mass as a result of the ~3 mDa mass defect between 2H and 13C atoms. Previous HDX MS methods did not resolve these isotopomers, requiring a natural-abundance-only (before HDX or “time zero”) spectrum and data processing to remove its contribution. It is demonstrated here that high-resolution mass spectrometry can be used to detect isotopic fine structure, such as in the A + 2 profile example above, deconvolving the isotopomer species resulting from deuterium incorporation. Resolving isotopic fine structure during HDX MS therefore permits direct monitoring of HDX, which can be calculated as the sum of the fractional peak magnitudes of the deuterium-exchanged isotopomers. This obviates both the need for a time zero spectrum as well as data processing to account for natural abundance heavy isotopes, saving instrument and analysis time. PMID:24328359

  4. Modeling the selectivity of activated carbons for efficient separation of hydrogen and carbon dioxide

    E-print Network

    Wu, Jianzhong

    the separation of hydrogen and carbon dioxide via adsorption in activated carbons. In the simulations, both hydrogen and carbon dioxide molecules are modeled as Lennard-Jones spheres, and the activated carbons essentially no preference over the two gases and the selectivity of carbon dioxide relative to hydrogen falls

  5. 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.

  6. Deuterium-Tritium Pulse Propulsion with Hydrogen as Propellant and the Entire Spacecraft as a Gigavolt Capacitor for Ignition

    E-print Network

    Winterberg, Friedwardt

    2012-01-01

    A deuterium-tritium (DT) nuclear pulse propulsion concept for fast interplanetary transport is proposed utilizing almost all the energy for thrust and without the need for a large radiator: 1. By letting the thermonuclear micro-explosion take place in the center of a liquid hydrogen sphere with the radius of the sphere large enough to slow down and absorb the neutrons of the DT fusion reaction, heating the hydrogen to a fully ionized plasma at a temperature of ~ 105 K. 2. By using the entire spacecraft as a magnetically insulated gigavolt capacitor, igniting the DT micro-explosion with an intense GeV ion beam discharging the gigavolt capacitor, possible if the space craft has the topology of a torus.

  7. Deuterium-Tritium Pulse Propulsion with Hydrogen as Propellant and the Entire Spacecraft as a Gigavolt Capacitor for Ignition

    E-print Network

    Friedwardt Winterberg

    2012-07-31

    A deuterium-tritium (DT) nuclear pulse propulsion concept for fast interplanetary transport is proposed utilizing almost all the energy for thrust and without the need for a large radiator: 1. By letting the thermonuclear micro-explosion take place in the center of a liquid hydrogen sphere with the radius of the sphere large enough to slow down and absorb the neutrons of the DT fusion reaction, heating the hydrogen to a fully ionized plasma at a temperature of ~ 105 K. 2. By using the entire spacecraft as a magnetically insulated gigavolt capacitor, igniting the DT micro-explosion with an intense GeV ion beam discharging the gigavolt capacitor, possible if the space craft has the topology of a torus.

  8. Qualitative and quantitative analysis of mixtures of compounds containing both hydrogen and deuterium

    NASA Technical Reports Server (NTRS)

    Crespi, H. L.; Harkness, L.; Katz, J. J.; Norman, G.; Saur, W.

    1969-01-01

    Method allows qualitative and quantitative analysis of mixtures of partially deuterated compounds. Nuclear magnetic resonance spectroscopy determines location and amount of deuterium in organic compounds but not fully deuterated compounds. Mass spectroscopy can detect fully deuterated species but not the location.

  9. Gas chromatography flow rates for determining deuterium/hydrogen ratios of natural gas by gas chromatography/high-temperature conversion/isotope ratio mass spectrometry.

    PubMed

    Jia, Wanglu; Peng, Ping'an; Liu, Jinzhong

    2008-08-01

    The effects of the gas chromatography flow rate on the determination of the deuterium/hydrogen (D/H) ratios of natural gas utilising gas chromatography/high-temperature conversion/isotope ratio mass spectrometry (GC/TC/IRMS) have been evaluated. In general, the measured deltaD values of methane, ethane and propane decrease with increase in column flow rate. When the column flow rate is 1 mL/min or higher, which is commonly used for the determination of D/H ratios of natural gas, the organic H in gas compounds may not be completely converted into hydrogen gas. Based on the results of experiments conducted on a GC column with an i.d. of 0.32 mm, a GC flow rate of 0.6 mL/min is proposed for determining the D/H ratios of natural gas by GC/TC/IRMS. Although this value may be dependent on the instrument conditions used in this work, we believe that correct deltaD values of organic compounds with a few carbon atoms are obtained only when relatively low GC flow rates are used for D/H analysis by GC/TC/IRMS. Moreover, as the presence of trace water could significantly affect the determination of D/H ratios, a newly designed inlet liner was used to remove trace water contained in some gas samples. PMID:18636428

  10. Structural comparison of recombinant human macrophage colony stimulating factor ? and a partially reduced derivative using hydrogen deuterium exchange and electrospray ionization mass spectrometry

    PubMed Central

    Zhang, Y. Heidi; Yan, Xuguang; Maier, Claudia S.; Schimerlik, Michael I.; Deinzer, Max L.

    2001-01-01

    Hydrogen deuterium exchange, monitored by electrospray ionization mass spectrometry, has been employed to characterize structural features of a derivative of recombinant human macrophage colony stimulating factor beta (rhm-CSF?) in which two of the nine disulfide bridges (Cys157/Cys159–Cys`157/Cys`159) were selectively reduced and alkylated. Removal of these two disulfide bridges did not affect the biological activity of the protein. Similarities between CD and fluorescence spectra for rhm-CSF? and its derivative indicate that removing the disulfide bonds did not strongly alter the overall three-dimensional structure of rhm-CSF?. However, differences between deuterium exchange data of the intact proteins indicate that more NHs underwent fast deuterium exchange in the derivative than in rhm-CSF?. Regions located near the disulfide bond removal site were shown to exhibit faster deuterium exchange behavior in the derivative than in rhm-CSF?. PMID:11604539

  11. Catalytic carbon membranes for hydrogen production

    SciTech Connect

    Damle, A.S.; Gangwal, S.K.

    1992-01-01

    Commercial carbon composite microfiltration membranes may be modified for gas separation applications by providing a gas separation layer with pores in the 1- to 10-nm range. Several organic polymeric precursors and techniques for depositing a suitable layer were investigated in this project. The in situ polymerization technique was found to be the most promising, and pure component permeation tests with membrane samples prepared with this technique indicated Knudsen diffusion behavior. The gas separation factors obtained by mixed-gas permeation tests were found to depend strongly on gas temperature and pressure indicating significant viscous flow at high-pressure conditions. The modified membranes were used to carry out simultaneous water gas shift reaction and product hydrogen separation. These tests indicated increasing CO conversions with increasing hydrogen separation. A simple process model was developed to simulate a catalytic membrane reactor. A number of simulations were carried out to identify operating conditions leading to product hydrogen concentrations over 90 percent. (VC)

  12. Hydrogen storage in engineered carbon nanospaces.

    PubMed

    Burress, Jacob; Kraus, Michael; Beckner, Matt; Cepel, Raina; Suppes, Galen; Wexler, Carlos; Pfeifer, Peter

    2009-05-20

    It is shown how appropriately engineered nanoporous carbons provide materials for reversible hydrogen storage, based on physisorption, with exceptional storage capacities (approximately 80 g H2/kg carbon, approximately 50 g H2/liter carbon, at 50 bar and 77 K). Nanopores generate high storage capacities (a) by having high surface area to volume ratios, and (b) by hosting deep potential wells through overlapping substrate potentials from opposite pore walls, giving rise to a binding energy nearly twice the binding energy in wide pores. Experimental case studies are presented with surface areas as high as 3100 m(2) g(-1), in which 40% of all surface sites reside in pores of width approximately 0.7 nm and binding energy approximately 9 kJ mol(-1), and 60% of sites in pores of width>1.0 nm and binding energy approximately 5 kJ mol(-1). The findings, including the prevalence of just two distinct binding energies, are in excellent agreement with results from molecular dynamics simulations. It is also shown, from statistical mechanical models, that one can experimentally distinguish between the situation in which molecules do (mobile adsorption) and do not (localized adsorption) move parallel to the surface, how such lateral dynamics affects the hydrogen storage capacity, and how the two situations are controlled by the vibrational frequencies of adsorbed hydrogen molecules parallel and perpendicular to the surface: in the samples presented, adsorption is mobile at 293 K, and localized at 77 K. These findings make a strong case for it being possible to significantly increase hydrogen storage capacities in nanoporous carbons by suitable engineering of the nanopore space. PMID:19420674

  13. Hydrogen storage in engineered carbon nanospaces

    NASA Astrophysics Data System (ADS)

    Burress, Jacob; Kraus, Michael; Beckner, Matt; Cepel, Raina; Suppes, Galen; Wexler, Carlos; Pfeifer, Peter

    2009-05-01

    It is shown how appropriately engineered nanoporous carbons provide materials for reversible hydrogen storage, based on physisorption, with exceptional storage capacities (~80 g H2/kg carbon, ~50 g H2/liter carbon, at 50 bar and 77 K). Nanopores generate high storage capacities (a) by having high surface area to volume ratios, and (b) by hosting deep potential wells through overlapping substrate potentials from opposite pore walls, giving rise to a binding energy nearly twice the binding energy in wide pores. Experimental case studies are presented with surface areas as high as 3100 m2 g-1, in which 40% of all surface sites reside in pores of width ~0.7 nm and binding energy ~9 kJ mol-1, and 60% of sites in pores of width>1.0 nm and binding energy ~5 kJ mol-1. The findings, including the prevalence of just two distinct binding energies, are in excellent agreement with results from molecular dynamics simulations. It is also shown, from statistical mechanical models, that one can experimentally distinguish between the situation in which molecules do (mobile adsorption) and do not (localized adsorption) move parallel to the surface, how such lateral dynamics affects the hydrogen storage capacity, and how the two situations are controlled by the vibrational frequencies of adsorbed hydrogen molecules parallel and perpendicular to the surface: in the samples presented, adsorption is mobile at 293 K, and localized at 77 K. These findings make a strong case for it being possible to significantly increase hydrogen storage capacities in nanoporous carbons by suitable engineering of the nanopore space.

  14. Comparison of the addition of hydrogen, helium, and deuterium gases in the separation of uranium isotopes according to the separation of nozzle process

    Microsoft Academic Search

    Heeschen

    1972-01-01

    In the separation of uranium isotopes by the separation nozzle prccess, ; a mixture of UFâ with a light addition gas is used as the processing gas. ; The influence of the additional gases hydrogen, deuterium, and helium on the fiow ; rate of the gas mixture in the nozzle and the separation of the uranium isotopes ; was studied,

  15. MECHANICAL TESTING OF CARBON STEEL IN HIGH PRESSURE HYDROGEN

    Microsoft Academic Search

    2006-01-01

    The methods and interim results from a testing program to quantify hydrogen effects on mechanical properties of carbon steel pipeline and pipeline weld materials are provided. The scope is carbon steels commonly used for natural gas pipelines in the United States that are candidates for hydrogen service in the hydrogen economy. The mechanical test results will be applied in future

  16. Hydrogen Raman shifts in carbon nanotubes from molecular dynamics simulation

    E-print Network

    Brenner, Donald W.

    Hydrogen Raman shifts in carbon nanotubes from molecular dynamics simulation S.J.V. Frankland *, D hydrogen in individual single-shell carbon nanotubes and nanotube ropes using a semiclassical model. The calculations predict that isolated hydrogen molecules inside of nanotubes have a Raman frequency that increases

  17. Hydrogen storage on chemically activated carbons and carbon nanomaterials at high pressures

    Microsoft Academic Search

    M. Jordá-Beneyto; F. Suárez-García; D. Lozano-Castelló; D. Cazorla-Amorós; A. Linares-Solano

    2007-01-01

    Hydrogen adsorption measurements have been carried out at different temperatures (298K and 77K) and high pressure on a series of chemically activated carbons with a wide range of porosities and also on other types of carbon materials, such as activated carbon fibers, carbon nanotubes and carbon nanofibers. This paper provides a useful interpretation of hydrogen adsorption data according to the

  18. Hydrogenated amorphous carbon grains in Comet Halley?

    NASA Astrophysics Data System (ADS)

    Colangeli, L.; Schwehm, G.; Bussoletti, E.; Fonti, S.; Blanco, A.; Orofino, V.

    1990-01-01

    Recent IR observations of Comets Halley, Wilson, and Bradfield have shown the existence of an emission feature falling at around 3.4 microns. In this paper, it is shown that a good fit of both the IR continuum and the band can be obtained by assuming a simple thermal emission model based upon the optical properties of hydrogenated amorphous carbon (HAC) grains, measured in laboratory. The best fits of P/Halley's spectra are obtained for HAC dust amounts which appear consistent with the constraints imposed by the observed production rates. The presence of amorphous carbon solid particles is also supported on the basis of in situ mass spectrometry measurements performed by the Vega 1/2 and Giotto spacecraft in the environment of P/Halley. At present, it appears reasonable to suggest that amorphous carbon grains are able to match the observations and can be considered among likely candidates for cometary materials.

  19. Gas-Phase Hydrogen-Deuterium Exchange Labeling of Select Peptide Ion Conformer Types: a Per-Residue Kinetics Analysis.

    PubMed

    Khakinejad, Mahdiar; Kondalaji, Samaneh Ghassabi; Tafreshian, Amirmahdi; Valentine, Stephen J

    2015-07-01

    The per-residue, gas-phase hydrogen deuterium exchange (HDX) kinetics for individual amino acid residues on selected ion conformer types of the model peptide KKDDDDDIIKIIK have been examined using ion mobility spectrometry (IMS) and HDX-tandem mass spectrometry (MS/MS) techniques. The [M + 4H](4+) ions exhibit two major conformer types with collision cross sections of 418 Å(2) and 446 Å(2); the [M + 3H](3+) ions also yield two different conformer types having collision cross sections of 340 Å(2) and 367 Å(2). Kinetics plots of HDX for individual amino acid residues reveal fast- and slow-exchanging hydrogens. The contributions of each amino acid residue to the overall conformer type rate constant have been estimated. For this peptide, N- and C-terminal K residues exhibit the greatest contributions for all ion conformer types. Interior D and I residues show decreased contributions. Several charge state trends are observed. On average, the D residues of the [M + 3H](3+) ions show faster HDX rate contributions compared with [M + 4H](4+) ions. In contrast the interior I8 and I9 residues show increased accessibility to exchange for the more elongated [M + 4H](4+) ion conformer type. The contribution of each residue to the overall uptake rate showed a good correlation with a residue hydrogen accessibility score model calculated using a distance from charge site and initial incorporation site for nominal structures obtained from molecular dynamic simulations (MDS). Graphical Abstract ?. PMID:25895891

  20. Enhanced gas-phase hydrogen-deuterium exchange of oligonucleotide and protein ions stored in an external multipole ion reservoir.

    PubMed

    Hofstadler, S A; Sannes-Lowery, K A; Griffey, R H

    2000-01-01

    Rapid gas-phase hydrogen-deuterium (H-D) exchange from D(2)O and ND(3) into oligonucleotide and protein ions was achieved during storage in a hexapole ion reservoir. Deuterated gas is introduced through a capillary line that discharges directly into the low-pressure region of the reservoir. Following exchange, the degree of H-D exchange is determined using Fourier transform ion cyclotron resonance mass spectrometry. Gas-phase H-D exchange experiments can be conducted more than 100 times faster than observed using conventional in-cell exchange protocols that require lower gas pressures and additional pump-down periods. The short experimental times facilitate the quantitation of the number of labile hydrogens for less reactive proteins and structured oligonucleotides. For ubiquitin, we observe approximately 65 H-D exchanges after 20 s. Exchange rates of > 250 hydrogens s(-1) are observed for oligonucleotide ions when D(2)O or ND(3) is admitted directly into the external ion reservoir owing to the high local pressure in the hexapole. Partially deuterated oligonucleotide ions have been fragmented in the reservoir using infrared multiphoton dissociation (IRMPD). The resulting fragment ions show that exchange predominates at charged sites on the 5'- and 3'-ends of the oligonucleotide, whereas exchange is slower in the core. This hardware configuration is independent of the mass detector and should be compatible with other mass spectrometric platforms including quadrupole ion trap and time-of-flight mass spectrometers. PMID:10633235

  1. Hydrogen-bond-dynamics-based switching of conductivity and magnetism: a phase transition caused by deuterium and electron transfer in a hydrogen-bonded purely organic conductor crystal.

    PubMed

    Ueda, Akira; Yamada, Shota; Isono, Takayuki; Kamo, Hiromichi; Nakao, Akiko; Kumai, Reiji; Nakao, Hironori; Murakami, Youichi; Yamamoto, Kaoru; Nishio, Yutaka; Mori, Hatsumi

    2014-08-27

    A hydrogen bond (H-bond) is one of the most fundamental and important noncovalent interactions in chemistry, biology, physics, and all other molecular sciences. Especially, the dynamics of a proton or a hydrogen atom in the H-bond has attracted increasing attention, because it plays a crucial role in (bio)chemical reactions and some physical properties, such as dielectricity and proton conductivity. Here we report unprecedented H-bond-dynamics-based switching of electrical conductivity and magnetism in a H-bonded purely organic conductor crystal, ?-D3(Cat-EDT-TTF)2 (abbreviated as ?-D). This novel crystal ?-D, a deuterated analogue of ?-H3(Cat-EDT-TTF)2 (abbreviated as ?-H), is composed only of a H-bonded molecular unit, in which two crystallographically equivalent catechol-fused ethylenedithiotetrathiafulvalene (Cat-EDT-TTF) skeletons with a +0.5 charge are linked by a symmetric anionic [O···D···O](-1)-type strong H-bond. Although the deuterated and parent hydrogen systems, ?-D and ?-H, are isostructural paramagnetic semiconductors with a dimer-Mott-type electronic structure at room temperature (space group: C2/c), only ?-D undergoes a phase transition at 185 K, to change to a nonmagnetic insulator with a charge-ordered electronic structure (space group: P1). The X-ray crystal structure analysis demonstrates that this dramatic switching of the electronic structure and physical properties originates from deuterium transfer or displacement within the H-bond accompanied by electron transfer between the Cat-EDT-TTF ?-systems, proving that the H-bonded deuterium dynamics and the conducting TTF ?-electron are cooperatively coupled. Furthermore, the reason why this unique phase transition occurs only in ?-D is qualitatively discussed in terms of the H/D isotope effect on the H-bond geometry and potential energy curve. PMID:25127315

  2. Photobiological hydrogen production and carbon dioxide sequestration

    NASA Astrophysics Data System (ADS)

    Berberoglu, Halil

    Photobiological hydrogen production is an alternative to thermochemical and electrolytic technologies with the advantage of carbon dioxide sequestration. However, it suffers from low solar to hydrogen energy conversion efficiency due to limited light transfer, mass transfer, and nutrient medium composition. The present study aims at addressing these limitations and can be divided in three parts: (1) experimental measurements of the radiation characteristics of hydrogen producing and carbon dioxide consuming microorganisms, (2) solar radiation transfer modeling and simulation in photobioreactors, and (3) parametric experiments of photobiological hydrogen production and carbon dioxide sequestration. First, solar radiation transfer in photobioreactors containing microorganisms and bubbles was modeled using the radiative transport equation (RTE) and solved using the modified method of characteristics. The study concluded that Beer-Lambert's law gives inaccurate results and anisotropic scattering must be accounted for to predict the local irradiance inside a photobioreactor. The need for accurate measurement of the complete set of radiation characteristics of microorganisms was established. Then, experimental setup and analysis methods for measuring the complete set of radiation characteristics of microorganisms have been developed and successfully validated experimentally. A database of the radiation characteristics of representative microorganisms have been created including the cyanobacteria Anabaena variabilis, the purple non-sulfur bacteria Rhodobacter sphaeroides and the green algae Chlamydomonas reinhardtii along with its three genetically engineered strains. This enabled, for the first time, quantitative assessment of the effect of genetic engineering on the radiation characteristics of microorganisms. In addition, a parametric experimental study has been performed to model the growth, CO2 consumption, and H 2 production of Anabaena variabilis as functions of irradiance and CO2 concentration. Kinetic models were successfully developed based on the Monod model and on a novel scaling analysis employing the CO2 consumption half-time as the time scale. Finally, the growth and hydrogen production of Anabaena variabilis have been compared in a flat panel photobioreactor using three different nutrient media under otherwise similar conditions. Light to hydrogen energy conversion efficiency for Allen-Arnon medium was superior by a factor of 5.5 to both BG-11 and BG-11o media. This was attributed to the presence of vanadium and larger heterocyst frequency observed in the Allen-Arnon medium.

  3. The Speed of Oil and Mercury Diffusion Pumps for Hydrogen, Helium and Deuterium

    Microsoft Academic Search

    B. B. Dayton

    1948-01-01

    Data on several standard diffusion pumps indicate that the speed for hydrogen may be considerably less than 3.8 times the rated speed for air depending on the jet design, pump fluid, heater input, and speed of the fore pump. Evidence is presented that this reduction in speed is partly the result of diffusion of hydrogen back through the vapor jet

  4. Tunneling effects in the kinetics of helium and hydrogen isotopes desorption from single-walled carbon nanotube bundles

    SciTech Connect

    Danilchenko, B. A., E-mail: danil@iop.kiev.ua; Yaskovets, I. I.; Uvarova, I. Y. [Institute of Physics NASU, Pr. Nauki 46, 03680 Kiev (Ukraine); Dolbin, A. V.; Esel'son, V. B.; Basnukaeva, R. M.; Vinnikov, N. A. [B. Verkin Institute for Low Temperature Physics and Engineering NASU, 47 Lenin Ave., Kharkov 61103 (Ukraine)

    2014-04-28

    The kinetics of desorption both helium isotopes and molecules of hydrogen and deuterium from open-ended or ?-irradiated single-walled carbon nanotube bundles was investigated in temperature range of 10–300?K. The gases desorption rates obey the Arrhenius law at high temperatures, deviate from it with temperature reduction and become constant at low temperatures. These results indicate the quantum nature of gas outflow from carbon nanotube bundles. We had deduced the crossover temperature below which the quantum corrections to the effective activation energy of desorption become significant. This temperature follows linear dependence against the inverse mass of gas molecule and is consistent with theoretical prediction.

  5. Gaseous anion chemistry. Hydrogen-deuterium exchange in mono- and dialcohol alkoxide ions: ionization reactions in dialcohols

    SciTech Connect

    Lloyd, J.R.; Agosta, W.C.; Field, F.H.

    1980-08-15

    The subject of this work is H-D exchange in certain gaseous anions using D/sub 2/ as the exchanging agent. The anions involved are produced from ethylene glycol, 1,3-propanediol, 1,4-butanediol, ethanol, 1-propanol, and 1-butanol. Spectra and postulated ionization reactions for these mono- and dialcohols are given. Hydrogen-deuterium exchange occurs in the (M - 1)/sup -/ and (2M - 1)/sup -/ ions of ethylene glycol, 1,3-propanediol, and 1,4-butanediol. The amount of exchange occurring is 3-8 times greater in (2M - 1)/sup -/ than in (M - 1)/sup -/. The amount of H-D exchange occurring in ethanol, 1-propanol, and 1-butanol is small or zero in the (2M - 1)/sup -/ ions and in the (M - 1)/sup -/ ion for 1-butanol (the only (M - 1)/sup -/ ion which could be examined experimentally). The amount of exchange occurring in the (2M - 1)/sup -/ and (M - 1)/sup -/ ions from ethylene glycol is not affected by the total pressure or composition of the reaction mixture in the ionization chamber of the mass spectrometer. A novel hydrogen-bridging mechanism is suggested to account for the observed exchange occurring in the dialcohols.

  6. Combined hydrogen production and storage with subsequent carbon crystallization.

    PubMed

    Lueking, Angela D; Gutierrez, Humberto R; Fonseca, Dania A; Narayanan, Deepa L; Van Essendelft, Dirk; Jain, Puja; Clifford, Caroline E B

    2006-06-21

    We provide evidence of low-temperature hydrogen evolution and possible hydrogen trapping in an anthracite coal derivative, formed via reactive ball milling with cyclohexene. No molecular hydrogen is added to the process. Raman-active molecular hydrogen vibrations are apparent in samples at atmospheric conditions (300 K, 1 bar) for samples prepared 1 year previously and stored in ambient air. Hydrogen evolves slowly at room temperature and is accelerated upon sample heating, with a first increase in hydrogen evolution occurring at approximately 60 degrees C. Subsequent chemical modification leads to the observation of crystalline carbons, including nanocrystalline diamond surrounded by graphene ribbons, other sp2-sp3 transition regions, purely graphitic regions, and a previously unidentified crystalline carbon form surrounded by amorphous carbon. The combined evidence for hydrogen trapping and carbon crystallization suggests hydrogen-induced crystallization of the amorphous carbon materials, as metastable hydrogenated carbons formed via the high-energy milling process rearrange into more thermodynamically stable carbon forms and molecular hydrogen. PMID:16771488

  7. Confinement of hydrogen at high pressure in carbon nanotubes

    DOEpatents

    Lassila, David H. (Aptos, CA); Bonner, Brian P. (Livermore, CA)

    2011-12-13

    A high pressure hydrogen confinement apparatus according to one embodiment includes carbon nanotubes capped at one or both ends thereof with a hydrogen-permeable membrane to enable the high pressure confinement of hydrogen and release of the hydrogen therethrough. A hydrogen confinement apparatus according to another embodiment includes an array of multi-walled carbon nanotubes each having first and second ends, the second ends being capped with palladium (Pd) to enable the high pressure confinement of hydrogen and release of the hydrogen therethrough as a function of palladium temperature, wherein the array of carbon nanotubes is capable of storing hydrogen gas at a pressure of at least 1 GPa for greater than 24 hours. Additional apparatuses and methods are also presented.

  8. Hydrogen/Deuterium Exchange and Electron-Transfer Dissociation Mass Spectrometry Determine the Interface and Dynamics of Apolipoprotein E Oligomerization

    PubMed Central

    Huang, Richard Y-C.; Garai, Kanchan; Frieden, Carl; Gross, Michael L.

    2011-01-01

    Apolipoprotein E, a 34 kDa protein, plays a key role in triglyceride and cholesterol metabolism. Of the three common isoforms (ApoE2, 3 and 4), only ApoE4 is a risk factor for Alzheimer’s Disease. All three isoforms of wild-type ApoE self-associate to form oligomers, a process that may have functional consequences. Although the C-terminal domain, residues 216–299, of ApoE is believed to mediate self-association, the specific residues involved in this process are not known. Here we report the use of hydrogen/deuterium exchange (H/DX) coupled with enzymatic digestion to identify those regions in the sequence of full-length apoE involved in oligomerization. For this determination, we compared the results of H/DX of the wild-type proteins and those of monomeric forms obtained by modifying four residues in the C-terminal domain. The three wild type and mutant isoforms show similar structures based on their similar H/DX kinetics and extents of exchange. Regions of the C-terminus (residues 230–270) of the ApoE isoforms show significant differences of deuterium uptake between oligomeric and monomeric forms, confirming that oligomerization occurs at these regions. To achieve single amino acid resolution, we examined the extents of H/DX by using electron transfer dissociation (ETD) fragmentation of peptides representing selected regions of both the monomeric and the oligomeric forms of ApoE4. From these experiments, we could identify the specific residues involved in ApoE oligomerization. In addition, our results verify that ApoE4 is composed of a compact structure at its N-terminal domain. Regions of C-terminal domain, however, appear to lack defined structure. PMID:21899263

  9. Carbon assisted water electrolysis for hydrogen generation

    NASA Astrophysics Data System (ADS)

    Sabareeswaran, S.; Balaji, R.; Ramya, K.; Rajalakshmi, N.; Dhathathereyan, K. S.

    2013-06-01

    Carbon Assisted Water Electrolysis (CAWE) is an energy efficient process in that H2 can be produced at lower applied voltage (˜1.0 V) compared to nearly 2.0 V needed for ordinary water electrolysis for the same H2 evolution rate. In this process, carbon is oxidized to oxides of carbon at the anode of an electrochemical cell and hydrogen is produced at the cathode. These gases are produced in relatively pure state and would be collected in a separate chamber. In this paper, we present the results of influence of various operating parameters on efficiency of CAWE process. The results showed that H2 can be produced at applied voltages Eo as low as 1.0V (vs. SHE) and its production rate is strongly dependent on the type of the carbon used and its concentration in the electrolyte. It has also been found that the performance of CAWE process is higher in acidic electrolyte than in alkaline electrolyte.

  10. Relaxation of vibrational energy of deuterium on surface of solid carbon dioxide. II

    Microsoft Academic Search

    N. M. Vasilev; S. A. Kovalevskii; M. A. Kozhushner; B. R. Shub

    1982-01-01

    Various models have been examined for the relaxation of vibrational energy of excited deuterium molecules adsorbed on the surface of a frozen layer of COâ. Estimates of the probability of relaxation through different mechanisms led to the following basic mechanism: Dâ(v=1)+COâ(000)..-->..Dâ(v=0)+COâ(001)+..delta..E, where ..delta..E = 620 cm⁻¹ is the energy released to rotational and translational degrees of freedom of the deuterium

  11. TRANSITION METAL ACTIVATION AND FUNCTIONALIZATION OF CARBON-HYDROGEN BONDS

    E-print Network

    Jones, William D.

    TRANSITION METAL ACTIVATION AND FUNCTIONALIZATION OF CARBON-HYDROGEN BONDS William D. Jones-H and C-C bond functionalization, and (4) carbon-fluorine bond activation. We have made progress in each in our proposal where we have had success. These include: (1) carbon-carbon bond cleavage reactions, (2

  12. Investigation of the effect of intra-molecular interactions on the gas-phase conformation of peptides as probed by ion mobility-mass spectrometry, gas-phase hydrogen/deuterium exchange, and molecular mechanics 

    E-print Network

    Sawyer, Holly Ann

    2006-04-12

    Ion mobility-mass spectrometry (IM-MS), gas-phase hydrogen/deuterium (H/D) exchange ion molecule reactions and molecular modeling provide complimentary information and are used here for the characterization of peptide ion structure, including fine...

  13. Development and implementation of a FT-ICR mass spectrometer for the investigation of ion conformations of peptide sequence isomers containing basic amino acid residues by gas-phase hydrogen/deuterium exchange

    E-print Network

    Marini, Joseph Thomas

    2004-09-30

    The gas-phase hydrogen/deuterium (H/D) exchange of protonated di- and tripeptides containing a basic amino acid residue has been studied with a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. Bimolecular reactions...

  14. Development and implementation of a FT-ICR mass spectrometer for the investigation of ion conformations of peptide sequence isomers containing basic amino acid residues by gas-phase hydrogen/deuterium exchange 

    E-print Network

    Marini, Joseph Thomas

    2004-09-30

    The gas-phase hydrogen/deuterium (H/D) exchange of protonated di- and tripeptides containing a basic amino acid residue has been studied with a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. Bimolecular ...

  15. Mass production of multiwalled carbon nanotubes by hydrogen arc discharge

    Microsoft Academic Search

    Yoshinori Ando; Xinluo Zhao; Sakae Inoue; Sumio Iijima

    2002-01-01

    Highly graphitized multiwalled carbon nanotubes (MWNTs) were mass-produced by hydrogen arc discharge with automatic feeding of carbon electrode. Refluxing them first in hydrogen peroxide and then in a mixture of sulfuric and nitric acids was carried out for purification of MWNTs. The purification process of MWNTs was evaluated by scanning electron microscopy. Nanostructure and crystalline perfection of the purified MWNTs

  16. Review of hydrogen storage by adsorption in carbon nanotubes

    Microsoft Academic Search

    F. Lamari Darkrim; P. Malbrunot; G. P. Tartaglia

    2002-01-01

    This work deals with hydrogen adsorption in carbon nanotube materials over a wide range of pressure and temperature in order to establish the reliability of this phenomenon as a valuable storage technique of hydrogen. Our purpose is to give, discuss and compare the different results published comprising our works. Both experimental and simulation adsorption data concerning the hydrogen gas within

  17. Evidence for site-specific intra-ionic hydrogen/deuterium exchange in the low-energy collision-induced dissociation product ion spectra of protonated small molecules generated by electrospray ionisation.

    PubMed

    Holman, Stephen W; Wright, Patricia; Wells, Neil J; Langley, G John

    2010-04-01

    The experimental investigation of site-specific intra-ionic hydrogen/deuterium (H/D) exchange in the low-energy collision-induced dissociation (CID) product ion spectra of protonated small molecules generated by electrospray ionisation (ESI) is presented. The observation of intra-ionic H/D exchange in such ions under low-energy CID conditions has hitherto been rarely reported. The data suggest that the intra-ionic H/D exchange takes place in a site-specific manner between the ionising deuteron, localised at either a tertiary amine or a tertiary amine-N-oxide, and a gamma-hydrogen relative to the nitrogen atom. Nuclear magnetic resonance (NMR) spectroscopy measurements showed that no H/D exchange takes place in solution, indicating that the reaction occurs in the gas phase. The compounds analysed in this study suggested that electron-withdrawing groups bonded to the carbon atom bearing the gamma-hydrogen can preclude exchange. The effect of the electron-withdrawing group appears dependent upon its electronegativity, with lower chi value groups still allowing exchange to take place. However, the limited dataset available in this study prevented robust conclusions being drawn regarding the effect of the electron-withdrawing group. The observation of site-specific intra-ionic H/D exchange has application in the area of structural elucidation, where it could be used to introduce an isotopic label into the carbon skeleton of a molecule containing specific structural features. This could increase the throughput, and minimise the cost, of such studies due to the obviation of the need to produce a deuterium-labelled analogue by synthetic means. PMID:20069530

  18. Synthesis, characterization and hydrogen storage studies on porous carbon

    NASA Astrophysics Data System (ADS)

    Ruz, Priyanka; Banerjee, Seemita; Pandey, M.; Sudarsan, V.

    2015-06-01

    Porous carbon sample has been prepared, using zeolite-Y as template followed by annealing at 800°C, with view to estimate the extent of hydrogen storage by the sample. Based on XRD, 13C MAS NMR and Raman spectroscopic studies it is confirmed that the porous Carbon sample contains only sp2 hybridized carbon. The hydrogen sorption isotherms have been recorded for the sample at 273, 223K and 123K and the maximum hydrogen absorption capacity is found to be 1.47wt% at 123K. The interaction energy of hydrogen with the carbon framework was determined to be ˜ 10 kJ mol-1at lower hydrogen uptake and gradually decreases with increase in hydrogen loading.

  19. Computational investigation and hydrogen\\/deuterium exchange of the fixed charge derivative tris(2,4,6-Trimethoxyphenyl) phosphonium: Implications for the aspartic acid cleavage mechanism

    Microsoft Academic Search

    Kristin A. Herrmann; Vicki H. Wysocki; Erich R. Vorpagel

    2005-01-01

    Aspartic acid (Asp)-containing peptides with the fixed charge derivative tris(2,4,6trimethoxyphenyl) phosphonium (tTMP-P+) were explored computationally and experimentally by hydrogen\\/deuterium (H\\/D) exchange and by fragmentation studies to probe\\u000a the phenomenon of selective cleavage C-terminal to Asp in the absence of a “mobile” proton. Ab initio modeling of the tTMP-P+ electrostatic potential shows that the positive charge is distributed on the phosphonium

  20. Comparison of the dynamics of hydrogen and deuterium dissolved in crystalline Pd 9Si 2 and Pd 3P 0.8

    Microsoft Academic Search

    T. J Udovic; C Karmonik; Q Huang; J. J Rush; M Vennström; Y Andersson; T. B Flanagan

    2002-01-01

    The bonding potentials of hydrogen and deuterium dissolved in the crystalline alloys Pd9Si2 and Pd3P0.8 have been studied by neutron scattering techniques. Neutron powder diffraction verifies that, in both alloys, the principal type of interstitial absorption site is the quadrilateral base of a Pd-defined pyramid situated on the face of an empty triangular prism. The neutron vibrational spectroscopy results indicate

  1. Liquid–solid phase transition of hydrogen and deuterium in silica aerogel

    SciTech Connect

    Van Cleve, E.; Worsley, M. A.; Kucheyev, S. O., E-mail: kucheyev@llnl.gov [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

    2014-10-28

    Behavior of hydrogen isotopes confined in disordered low-density nanoporous solids remains essentially unknown. Here, we use relaxation calorimetry to study freezing and melting of H{sub 2} and D{sub 2} in an ?85%-porous base-catalyzed silica aerogel. We find that liquid–solid transition temperatures of both isotopes inside the aerogel are depressed. The phase transition takes place over a wide temperature range of ?4?K and non-trivially depends on the liquid filling fraction, reflecting the broad pore size distribution in the aerogel. Undercooling is observed for both H{sub 2} and D{sub 2} confined inside the aerogel monolith. Results for H{sub 2} and D{sub 2} are extrapolated to tritium-containing hydrogens with the quantum law of corresponding states.

  2. Applications of hydrogen deuterium exchange (HDX) for the characterization of conformational dynamics in light-activated photoreceptors

    PubMed Central

    Lindner, Robert; Heintz, Udo; Winkler, Andreas

    2015-01-01

    Rational design of optogenetic tools is inherently linked to the understanding of photoreceptor function. Structural analysis of elements involved in signal integration in individual sensor domains provides an initial idea of their mode of operation, but understanding how local structural rearrangements eventually affect signal transmission to output domains requires inclusion of the effector regions in the characterization. However, the dynamic nature of these assemblies renders their structural analysis challenging and therefore a combination of high- and low-resolution techniques is required to appreciate functional aspects of photoreceptors. This review focuses on the potential of hydrogen-deuterium exchange coupled to mass spectrometry (HDX-MS) for complementing the structural characterization of photoreceptors. In this respect, the ability of HDX-MS to provide information on conformational dynamics and the possibility to address multiple functionally relevant states in solution render this methodology ideally suitable. We highlight recent examples demonstrating the potential of HDX-MS and discuss how these results can help to improve existing optogenetic systems or guide the design of novel optogenetic tools. PMID:26157802

  3. Fast Comparative Structural Characterization of Intact Therapeutic Antibodies Using Hydrogen-Deuterium Exchange and Electron Transfer Dissociation.

    PubMed

    Pan, Jingxi; Zhang, Suping; Chou, Albert; Hardie, Darryl B; Borchers, Christoph H

    2015-06-16

    Higher-order structural characterization plays an important role in many stages of therapeutic antibody production. Herein, we report a new top-down mass spectrometry approach for characterizing the higher-order structure of intact antibodies, by combining hydrogen/deuterium exchange (HDX), subzero temperature chromatography, and electron transfer dissociation on the Orbitrap mass spectrometer. Individual IgG domain-level deuteration information was obtained for 6 IgG domains on Herceptin (HER), which included the antigen binding sites. This is the first time that top-down HDX has been applied to an intact protein as large as 150 kDa, which has never been done before on any instrument. Ligand-binding induced structural differences in HER were determined to be located only on the variable region of the light chain. Global glycosylation profile of antibodies and HDX property of the glycoforms were also determined by accurate intact mass measurements. Although the presence of disulfide bonds prevent the current approach from being able to obtain amino acid level structural information within the disulfide-linked regions, the advantages such as minimal sample manipulation, fast workflow, very low level of back exchange, and simple data analysis, make it well-suited for fast comparative structural evaluation of intact antibodies. PMID:25927482

  4. Application of a new ensemble conserving quantum dynamics simulation algorithm to liquid para-hydrogen and ortho-deuterium.

    PubMed

    Smith, Kyle K G; Poulsen, Jens Aage; Nyman, Gunnar; Cunsolo, Alessandro; Rossky, Peter J

    2015-06-28

    We apply the Feynman-Kleinert Quasi-Classical Wigner (FK-QCW) method developed in our previous work [Smith et al., J. Chem. Phys. 142, 244112 (2015)] for the determination of the dynamic structure factor of liquid para-hydrogen and ortho-deuterium at state points of (T = 20.0 K, n = 21.24 nm(-3)) and (T = 23.0 K, n = 24.61 nm(-3)), respectively. When applied to this challenging system, it is shown that this new FK-QCW method consistently reproduces the experimental dynamic structure factor reported by Smith et al. [J. Chem. Phys. 140, 034501 (2014)] for all momentum transfers considered. This shows that FK-QCW provides a substantial improvement over the Feynman-Kleinert linearized path-integral method, in which purely classical dynamics are used. Furthermore, for small momentum transfers, it is shown that FK-QCW provides nearly the same results as ring-polymer molecular dynamics (RPMD), thus suggesting that FK-QCW provides a potentially more appealing algorithm than RPMD since it is not formally limited to correlation functions involving linear operators. PMID:26133416

  5. Imidazole C-2 Hydrogen/Deuterium Exchange Reaction at Histidine for Probing Protein Structure and Function with MALDI Mass Spectrometry

    PubMed Central

    Hayashi, Naoka; Kuyama, Hiroki; Nakajima, Chihiro; Kawahara, Kazuki; Miyagi, Masaru; Nishimura, Osamu; Matsuo, Hisayuki; Nakazawa, Takashi

    2015-01-01

    We present a mass spectrometric method for analyzing protein structure and function, based on the imidazole C-2 or histidine C?1 hydrogen/deuterium (H/D) exchange reaction, which is intrinsically second order with respect to the concentrations of the imidazolium cation and OD? in D2O. The second-order rate constant (k2) of this reaction was calculated from the pH-dependency of the pseudo-first-order rate constant (k?) obtained from the change of average mass ?Mr (0 ? ?Mr < 1) of a peptide fragment containing a defined histidine residue at incubation time (t) such that k? = ? [ln(1??Mr)]/t. We preferred using k2 rather than k? because k2max (maximal value of k2) was empirically related to pKa as illustrated with a Brønsted plot: logk2max=-0.7pKa+? (? is an arbitrary constant), so that we could analyze the effect of structure on the H/D-exchange rate in terms of log(k2max/k2) representing the deviation of k2 from k2max. In the catalytic site of bovine ribonuclease A, His12 showed much larger change in log(k2max/k2) compared with His119 upon binding with cytidine 3?-monophosphate, as anticipated from the X-ray structures and the possible change in solvent accessibility. However, there is a need of considering the hydrogen bonds of the imidazole group with non-dissociable groups to interpret an extremely slow H/D exchange rate of His48 in partially solvent-exposed situation. PMID:24606199

  6. Detection of Hydrogen Spillover in Palladium-Modified Activated Carbon Fibers During Hydrogen Adsorption

    SciTech Connect

    Contescu, Cristian I [ORNL; Brown, Craig [National Institute of Standards and Technology (NIST); Liu, Yun [National Institute of Standards and Technology (NIST); Bhat, Vinay V [ORNL; Gallego, Nidia C [ORNL

    2009-01-01

    Palladium-modified activated carbon fibers (Pd-ACF) are being evaluated for adsorptive hydrogen storage at near-ambient conditions because of their enhanced hydrogen uptake in comparison to Pd-free activated carbon fibers (ACF). The net uptake enhancement (at room temperature and 20 bar) is in excess of the amount corresponding to formation of Pd hydride, and is usually attributed to hydrogen spillover. In this paper, inelastic neutron scattering was used to demonstrate the formation of new C-H bonds in Pd-containing activated carbon fibers after exposure to hydrogen at 20 oC and 1.6 MPa, at the expense of physisorbed H2. This finding is a post-factum proof of the atomic nature of H species formed in presence of a Pd catalyst, and of their subsequent spillover and binding to the carbon support. Chemisorption of hydrogen may explain the reduction in hydrogen uptake from first to second adsorption cycle.

  7. Catalytic behavior of Group VIII transition metals in the deuterium-acrolein reaction

    SciTech Connect

    Touroude, R.

    1980-09-01

    The catalytic reactions between acrolein and deuterium over all the Group VIII transition metals were studied by microwave spectrometry. A high catalyst selectivity in the exchange reaction, in which hydrogen is replaced by deuterium in acrolein, was found. Over Rh, Pd, Ir, Ru, and Ni, hydrogens situated on the ..beta.. carbon were quasi-selectively exchanged while over Pt, Os, and especially Co, an additional exchange of the aldehydic hydrogen took place. Over Fe, the hydrogen situated on the ..cap alpha.. carbon and the aldehydic hydrogen were exchanged equally. An attempt is made to relate the nature of the exchange to hydrogenation, decarbonylation, and hydrogenolysis and several reaction mechanisms are proposed in addition to the classical Horiuti-Polanyi mechanism, which is restricted to hydrogenation of the C-C double bond.

  8. Mechanism of Hydrogen Trapping and Transport in Carbon Materials

    NASA Astrophysics Data System (ADS)

    Atsumi, H.

    Bulk hydrogen retention and hydrogen diffusion in graphite and carbon materials have been studied to estimate hydrogen recycling and tritium inventory in a fusion reactor environment. Hydrogen may permeate into a filler grain in the form of a hydrogen molecule, diffuse through crystallite boundaries and finally be trapped as hydrogen atoms at the edge surface of a crystallite. In the estimation of hydrogen transport, the activation energy of hydrogen diffusion can be determined from absorption experiments, and the activation energy of detrapping can be obtained from desorption experiments. The activation energies of hydrogen trapping are 2.6 eV in ordinary graphite and 4.4 eV for irradiated or mechanically milled graphite samples.

  9. Deuterium retention in codeposited layers and carbon materials exposed to high flux D-plasma

    NASA Astrophysics Data System (ADS)

    Arkhipov, I. I.; Gorodetsky, A. E.; Zalavutdinov, R. Kh; Zakharov, A. P.; Burtseva, T. A.; Mazul, I. V.; Khripunov, B. I.; Shapkin, V. V.; Petrov, V. B.

    A ceramic BCN target with samples of dense RG-Ti-91 without boron, RG-Ti-B with boron (0.1 at.%) and porous POCO AXF-5Q graphites was exposed in a stationary D-plasma of the `Lenta' device with an ion energy of 200 eV and an ion flux of (3 - 6) × 10 17 D/cm 2s at 1040 and 1400 K to a fluence of ˜1 × 10 22 D/cm 2. Codeposited layers were obtained for comparison on the target surface. Thermal desorption spectroscopy (TDS) showed that the amount of deuterium in RG-Ti after exposure at 1040 K was more than an order of magnitude higher than in POCO (9 × 10 17 and 7 × 10 16 D/cm 2, respectively). The retention took place preferentially in a surface layer about 100 ?m thick. The bulk deuterium concentration in both RG-Ti and POCO was lower than 1 appm. The irradiated RG-Ti surface was subjected to strong erosion and consisted of `columnar' grains covered with TiC at their tips. The deuterium in RG-Ti irradiated at 1400 K was located in the surface layer (1.5 × 10 16 D/cm 2). The value of the bulk concentration did not exceed 0.1 appm while in POCO it was equal to about 20 appm. TDS for deuterium in RG-Ti demonstrated a spectrum similar to that for codeposited layers on a target surface. The differences in deuterium retention in the graphites are explained on the basis of structural differences. Considering tritium inventory assessment for ITER, dense graphites like RG-Ti are preferred for working divertor plates at high temperatures.

  10. Equation of State Measurements of Hydrogen and Deuterium up to 2 Mbar

    NASA Astrophysics Data System (ADS)

    Collins, G. W.

    1997-07-01

    The high density and temperature equation of state of hydrogen is integral to many astrophysical and planetary models. We (This work was done in collaboration with L. B. DaSilva, P. Celliers, K. S. Budil, R. Cauble, D. Gold, N. C. Holmes, T. W. Barbee Jr, B. A. Hammel, J. D. Kilkenny, R. J. Wallace, R. Stewart, M. Ross, A. Ng and G. Chiu.) have used the Nova laser to produce uniform and steady shocks in H2 and D2 to probe this strongly-coupled region where molecular dissociation and electronic excitation occur. We present the pressure (from 0.25 to 2.1 Mbar) and density on the first Hugoniot, derived from shock speed, particle speed, and compression measurements of liquid H2 and D2. The data show a significant increase in compressibility near 1 Mbar compared to existing widely-used equation of state models.

  11. Nonthermal escape of hydrogen and deuterium from Venus and implications for loss of water

    NASA Technical Reports Server (NTRS)

    Kumar, S.; Hunten, D. M.; Pollack, J. B.

    1983-01-01

    As the dominant nonthermal mechanism for the escape of hydrogen in past Venus atmospheres, the charge exchange of H(+) with H would have provided an escape flux close to the diffusion-limiting value for H-mixing ratios up to 0.002 at the homopause, which also marks the onset of hydrodynamic flow. Charge exchange therefore represents a viable mechanism through which Venus could have lost up to an earth-equivalent ocean of water from its atmosphere over geologic time. Present Venus atmosphere estimates are based on in situ Pioneer Venus mission measurements, and assumptions in the course of extrapolation to past atmospheres have been with respect to the nature of the bulge, circulation pattern, and ion temperature.

  12. Stable carbon and hydrogen isotope fractionation of dissolved organic groundwater pollutants by equilibrium sorption.

    PubMed

    Höhener, Patrick; Yu, Xianjing

    2012-03-15

    Linear free energy relationships (LFERs) were established which relate equilibrium vapor-liquid isotope effects to stable carbon and hydrogen isotope enrichment factors for equilibrium sorption to geosorbents. The LFERs were established for normal, cyclic or branched alkanes, monoaromatic hydrocarbons, and chloroethenes. These LFERs predict that isotopic light compounds sorb more strongly than their heavy counterparts. Defining fractionation as in classical literature by "heavy divided by light", carbon enrichment factors for equilibrium sorption were derived which ranged from -0.13±0.04‰ (benzene) to -0.52±0.19‰ (trichloroethene at 5-15 °C). Hydrogen enrichment factors for sorption of 14 different compounds were between -2.4 and -9.2‰. For perdeuterated hydrocarbons the predicted enrichment factors ranged from -19±5.4‰ (benzene) to -64±30‰ (cyclohexane). Equilibrium sorption experiments with a soil and activated carbon as sorbents were performed in the laboratory for perdeuterocyclohexane and perdeuterotoluene. The measured D/H enrichments agreed with the LFER prediction for both compounds and both sorbents within the uncertainty estimate of the prediction. The results of this work suggest that equilibrium sorption does create only very small isotope shifts for (13)C in groundwater pollutants in aquifers. It is also suggested that deuterium shifts are expected to be higher, especially for strongly sorbing pollutants. PMID:22055158

  13. Carbon-Hydrogen and Carbon-Carbon Bond Activation of Cyclopropane by a Hydridotris(pyrazolyl)borate

    E-print Network

    Jones, William D.

    Carbon-Hydrogen and Carbon-Carbon Bond Activation of Cyclopropane by a Hydridotris and re-forming alkanes via carbon-carbon bond activation using heterogeneous catalysts is an important results in C-H activation of the hydrocarbon. The cyclopropyl hydride complex rearranges in benzene

  14. A simplified method for deuterium/hydrogen isotope ratio measurements on water samples of biological origin.

    PubMed

    Scrimgeour, C M; Rollo, M M; Mudambo, S M; Handley, L L; Prosser, S J

    1993-07-01

    Equilibration of hydrogen gas with the water in a variety of biological sample materials was carried out in Vacutainers using platinum-on-alumina catalyst physically isolated from the liquid water. The equilibration takes 3 days at room temperature--much slower than with catalysts which float on the water surface--but this reduces the short-term temperature sensitivity of the procedure, and the inexpensive materials used allow convenient disposal of biologically contaminated samples after analysis. The slow equilibration also allows time for complete exchange with water contained in a complex sample matrix such as plant stems or soil without the need for prior isolation of the water sample. The method has particular application in studies of human total body water where repeated studies can be carried out over a short time period without the need to wait for the previous dose to wash out. Water turnover rates from total diurnal energy expenditure studies measured by this method were not significantly different from those obtained by the zinc reduction method. PMID:8357854

  15. Sticking coefficient of hydrogen and deuterium on silicates under interstellar conditions

    E-print Network

    Chaabouni, H; Baouche, S; Dulieu, F; Matar, E; Congiu, E; Gavilan, L; Lemaire, J L

    2012-01-01

    Sticking of H and D atoms on interstellar dust grains is the first step in molecular hydrogen formation, which is a key reaction in the InterStellar Medium (ISM). After studying the sticking coefficients of H2 and D2 molecules on amorphous silicate surfaces experimentally and theoretically, we extrapolate the results to the sticking coefficient of atoms and propose a formulae that gives the sticking coefficients of H and D on both silicates and icy dust grains. In our experiments, we used the King and Wells method for measuring the sticking coefficients of H2 and D2 molecules on a silicate surface held at 10 K. It consists of measuring with a QMS (quadrupole mass spectrometer) the signals of H2 and D2 molecules reflected by the surface during the exposure of the sample to the molecular beam at a temperature ranging from 20 K to 340 K. We tested the efficiency of a physical model, developed previously for sticking on water-ice surfaces. We applied this model to our experimental results for the sticking coeffic...

  16. The deuterium content of atmospheric molecular hydrogen: Method and initial measurements

    NASA Astrophysics Data System (ADS)

    Gerst, Steve; Quay, Paul

    2000-11-01

    A new technique for determining the ?D of atmospheric molecular hydrogen (H2) at background mixing ratios is described in detail. An air sample is compressed into a high-pressure cylinder, after which the cylinder is cooled to -196°C to condense the air and generate a headspace greatly enriched in H2. The H2-enriched headspace is collected and admitted into a high-vacuum extraction line, where the H2 is separated from the headspace gases by combustion to water followed by cryogenic collection. The H2-derived water is then reduced back to H2 for measurement of its D/H content via isotope-ratio mass spectrometry. The primary limitation of the method is contamination during compressor collection and subsequent storage of air samples in high-pressure cylinders. The ?D of atmospheric H2 was measured on air samples collected between 46°N and 72°S during a research cruise in the Pacific Ocean during 1998 and at Cheeka Peak, Washington (48°N), during 1997-1999 and Point Barrow, Alaska (71°N), during 1996-1997. These measurements yield a global average ?D of atmospheric H2 of +130+/-4‰ and average Northern and Southern Hemispheric ?D values of +123+/-3‰ and +138+/-8‰, respectively (versus Vienna standard mean ocean water).

  17. Differential isotopic enrichment to facilitate characterization of asymmetric multimeric proteins using hydrogen/deuterium exchange mass spectrometry.

    PubMed

    Goswami, Devrishi; Tuske, Steve; Pascal, Bruce D; Bauman, Joseph D; Patel, Disha; Arnold, Eddy; Griffin, Patrick R

    2015-04-01

    Hydrogen/deuterium exchange (HDX) coupled to mass spectrometry has emerged as a powerful tool for analyzing the conformational dynamics of protein-ligand and protein-protein interactions. Recent advances in instrumentation and methodology have expanded the utility of HDX for the analysis of large and complex proteins; however, asymmetric dimers with shared amino acid sequence present a unique challenge for HDX because assignment of peptides with identical sequence to their subunit of origin remains ambiguous. Here we report the use of differential isotopic labeling to facilitate HDX analysis of multimers using HIV-1 reverse transcriptase (RT) as a model. RT is an asymmetric heterodimer of 51 kDa (p51) and 66 kDa (p66) subunits. The first 440 residues of p51 and p66 are identical. In this study differentially labeled RT was reconstituted from isotopically enriched ((15)N-labeled) p51 and unlabeled p66. To enable detection of (15)N-deuterated RT peptides, the software HDX Workbench was modified to follow a 100% (15)N model. Our results demonstrated that (15)N enrichment of p51 did not affect its conformational dynamics compared to unlabeled p51, but (15)N-labeled p51 did show different conformational dynamics than p66 in the RT heterodimer. Differential HDX-MS of isotopically labeled RT in the presence of the non-nucleoside reverse transcriptase inhibitor (NNRTI) efavirenz (EFV) showed subunit-specific perturbation in the rate of HDX consistent with previously published results and the RT-EFV cocrystal structure. PMID:25763479

  18. Deposition of carbon, deuterium and metals on the wall and limiters of TFTR

    SciTech Connect

    Wampler, W.R.; Doyle, B.L.; Lee, S.R.; Pontau, A.E.; Mills, B.E.; Causey, R.A.; Buchenauer, D.; Dylla, H.F.; Ulrickson, M.A.; LaMarche, P.H.

    1987-01-01

    Following a two year operational period the TFTR graphite fixed bumper limiter has been examined by a variety of methods. The areal density of metals was mapped in-situ by beta-backscattering. Several tiles were examined in detail by nuclear-reaction analysis, Rutherford backscattering and proton-induced x-ray emission to measure areal densities of deuterium and impurities. Some areas of the limiters were found to be covered by deposited material several microns thick. Other areas where the incident plasma flux is higher were much cleaner. Long-term collection coupons were also examined to characterize deposition on the wall. From these results the total amount of deuterium on the limiter and wall in TFTR is estimated to be about 1.3 x 10/sup 24/ atoms. The implications of this for wall-pumping effects and future tritium inventory are discussed. 11 refs., 5 figs., 1 tab.

  19. Hydrogen retention of carbon dust produced in JT-60

    NASA Astrophysics Data System (ADS)

    Yoshida, H.; Yamauchi, Y.; Hirohata, Y.; Arai, T.; Suzuki, S.; Akiba, M.; Miya, N.; Hino, T.

    2005-03-01

    Hydrogen retention of dust produced by hydrogen discharges from June 1987 to October 1987 in JT-60 was measured to contribute for the estimation of in-vessel tritium inventory in the next generation of fusion reactor, such as ITER. After venting the vacuum chamber, several types of dust-like pieces, i.e. flake-like carbon dust, graphite, and metal pieces, were found in the vacuum vessel. The amount of retained hydrogen in flake-like carbon dust was two orders of magnitude larger than that in the graphite and metal pieces. However, the hydrogen concentration of flake-like carbon dust was 0.04 in the atomic ratio of H/C, which was one order of magnitude smaller than that of carbon flake produced in JET. One of possible explanations is the difference of the wall temperature between JT-60 and JET.

  20. Hydrogen adsorption calculations in expanded graphite and amorphous carbons

    SciTech Connect

    Peng, L. [University of Tennessee, Knoxville (UTK); Morris, James R [ORNL

    2010-01-01

    This paper uses an efficient and accurate approach to estimate the hydrogen physisorption in various carbon structures. Compared with previous Grand Canonical Monte Carlo (GCMC) and other methods applied to expanded graphite, the method introduced here is shown to be accurate, but the calculation is much faster and more intuitive. Our preliminary results in amorphous carbons show high hydrogen uptake close to 0.8 wt-% at 300 K and moderate pressure.

  1. Rheological analysis of creep in hydrogenated amorphous carbon films

    Microsoft Academic Search

    Patrick Lemoine; John Paul Quinn; Paul Maguire; Pagona Papakonstantinou; Niall Dougan

    2006-01-01

    We present a nanoindentation study to detect time-dependent deformations in non-polymeric hydrogenated amorphous carbon films. When the bonded hydrogen content increases from 18 to 36 at.%, as measured by Fourier transform infrared spectroscopy, we find that the film becomes less graphitic and softer. Moreover, its hardness shows a larger sensitivity to strain rate and the film with the higher hydrogen content

  2. Hydrogen storage in ni nanoparticle-dispersed multiwalled carbon nanotubes.

    PubMed

    Kim, Hyun-Seok; Lee, Ho; Han, Kyu-Sung; Kim, Jin-Ho; Song, Min-Sang; Park, Min-Sik; Lee, Jai-Young; Kang, Jeung-Ku

    2005-05-12

    Hydrogen storage properties of mutiwalled carbon nanotubes (MWCNTs) with Ni nanoparticles were investigated. The metal nanoparticles were dispersed on MWCNTs surfaces using an incipient wetness impregnation procedure. Ni catalysts have been known to effectively dissociate hydrogen molecules in gas phase, providing atomic hydrogen possible to form chemical bonding with the surfaces of MWCNTs. Hydrogen desorption spectra of MWCNTs with 6 wt % of Ni nanoparticles showed that approximately 2.8 wt % hydrogen was released in the range of 340-520 K. In Kissinger's plot to evaluate the nature of interaction between hydrogen and MWCNTs with Ni nanoparticles, the hydrogen desorption activation energy was measured to be as high as approximately 31 kJ/mol.H(2), which is much higher than the estimates of pristine SWNTs. C-H(n)() stretching vibrations after hydrogenation in FTIR further supported that hydrogen molecules were dissociated when bound to the surfaces of MWCNTs. During cyclic hydrogen absorption/desorption, there was observed no significant decay in hydrogen desorption amount. The hydrogen chemisorption process facilitated by Ni nanopaticles could be suggested as an effective reversible hydrogen storage method. PMID:16852070

  3. Structure and intermolecular dynamics of aggregates populated during amyloid fibril formation studied by hydrogen/deuterium exchange.

    PubMed

    Carulla, Natàlia; Zhou, Min; Giralt, Ernest; Robinson, Carol V; Dobson, Christopher M

    2010-08-17

    The aggregation of proteins into amyloid fibrils is a complex and fascinating process associated with debilitating clinical disorders such as Alzheimer's and Parkinson's diseases. The process of aggregation involves a series of steps during which many intermediate aggregation states are populated. Recent evidence points to these intermediate states as the toxic moieties primarily responsible for cell damage or cell death, which are critical steps in the origin and progression of these disorders. To understand the molecular basis of these diseases, it is crucial to investigate and define the details of the aggregation process, and to achieve this objective, researchers need the tools to characterize the structure and kinetics of interconversion of the various species present during amyloid fibril formation. Hydrogen-deuterium (HD) exchange experiments are based on solvent accessibilities and provide one means by which this kind of information may be acquired. In this Account, we describe research based on HD exchange processes that is directed toward better understanding the dynamics and structural reorganizations involved in the formation of amyloid fibrils. Amide hydrogens that normally undergo rapid exchange with solvent hydrogens experience much slower exchange when involved in H-bonded structures or when sterically inaccessible to the solvent. The rates of exchange can be monitored by replacing some hydrogens with deuterons. When peptide and protein molecules assemble into amyloid fibrils, the fibrils contain a core region based on repetitive arrays of beta-sheets oriented parallel to the fibril axis. HD experiments have been applied extensively to map such structures in different amyloid fibril systems. By an extension of this approach, we have observed that HD exchange can be governed by a mechanism through which molecules making up the fibrils are continuously dissolving and reforming, revealing that amyloid fibrils are not static but dynamic structures. Under such circumstances, the kinetic parameters that define this "recycling" behavior can be determined, and they contain information that could be of significant value in the design of therapeutic strategies directed against amyloid-related diseases. More recently, to gain insights into the variety of intermediates that are thought to be involved in the aggregation process, we have applied a kinetic pulse labeling HD experiment that is able to characterize such species even if they are only transiently populated. Using this approach, we have been able to obtain structural insights into the different aggregates populated during the process of amyloid fibril formation as well as kinetic and mechanistic information on the structural reorganizations that take place during aggregation. HD exchange experiments, when carefully designed, constitute powerful tools for mapping the core structures of amyloid fibrils, for investigating the recycling of fibril components, and for characterizing the various types of structural reorganization that occur during aggregation. Such information is invaluable for understanding and addressing the molecular origins of the increasingly common and highly debilitating diseases associated with protein misfolding and aggregation. PMID:20557067

  4. Bulk stable carbon and deuterium isotope analyses of bitumen artifacts from Hacinebi Tepe, Turkey: reconstructing broad economic patterns of the Uruk expansion

    Microsoft Academic Search

    Mark Schwartz; David Hollander

    2008-01-01

    This research addresses issue of inter-regional trade for the world's first colonial trading system, the economic expansion of state societies from southern Mesopotamia into southwest Iran and southeast Anatolia, through the use of stable carbon and deuterium isotope analyses of bitumen artifacts. The key goal of the project was to get beyond simply the identification of trade (Schwartz, M., Hollander,

  5. ETD in a Traveling Wave Ion Guide at Tuned Z-Spray Ion Source Conditions Allows for Site-Specific Hydrogen/Deuterium Exchange Measurements

    NASA Astrophysics Data System (ADS)

    Rand, Kasper D.; Pringle, Steven D.; Morris, Michael; Engen, John R.; Brown, Jeffery M.

    2011-10-01

    The recent application of electron transfer dissociation (ETD) to measure the hydrogen exchange of proteins in solution at single-residue resolution (HX-ETD) paves the way for mass spectrometry-based analyses of biomolecular structure at an unprecedented level of detail. The approach requires that activation of polypeptide ions prior to ETD is minimal so as to prevent undesirable gas-phase randomization of the deuterium label from solution (i.e., hydrogen scrambling). Here we explore the use of ETD in a traveling wave ion guide of a quadrupole-time-of-flight (Q-TOF) mass spectrometer with a "Z-spray" type ion source, to measure the deuterium content of individual residues in peptides. We systematically identify key parameters of the Z-spray ion source that contribute to collisional activation and define conditions that allow ETD experiments to be performed in the traveling wave ion guide without gas-phase hydrogen scrambling. We show that ETD and supplemental collisional activation in a subsequent traveling wave ion guide allows for improved extraction of residue-specific deuterium contents in peptides with low charge. Our results demonstrate the feasibility, and illustrate the advantages of performing HX-ETD experiments on a high-resolution Q-TOF instrument equipped with traveling wave ion guides. Determination of parameters of the Z-spray ion source that contribute to ion heating are similarly pertinent to a growing number of MS applications that also rely on an energetically gentle transfer of ions into the gas-phase, such as the analysis of biomolecular structure by native mass spectrometry in combination with gas-phase ion-ion/ion-neutral reactions or ion mobility spectrometry.

  6. Optimum extracted H{sup {minus}} and D{sup {minus}} current densities from gas-pressure-limited high-power hydrogen/deuterium tandem ion sources

    SciTech Connect

    Hiskes, J.R.

    1993-07-14

    The tandem hydrogen/deuterium ion source is modelled for the purpose of identifying the maximum current densities that can be extracted subject to the gas-pressure constraints proposed for contemporary beam-line systems. Optimum useful extracted current densities are found to be in the range of approximately 7 to 10 mA cm{sup {minus}2}. The sensitivity of these current densities is examined subject to uncertainties in the underlying atomic/molecular rate processes; A principal uncertainty remains the quantification of the molecular vibrational distribution following H{sub 3{sup +}} wall collisions.

  7. CO/sub 2/DBr precursor geometry limited reaction of deuterium with carbon dioxide

    SciTech Connect

    Buelow, S.; Radhakrishnan, G.; Wittig, C.

    1987-10-08

    The authors report nascent OD(X/sup 2/II) rotational, vibrational, spin-orbit, and ..lambda..-doublet excitations from reactions of deuterium atoms with CO/sub 2/. D atoms are produced by the 193-nm photolysis of DBr (h nu - D/sub 0/ = 244 kJ mol/sup -1/) (i) within a weakly bonded CO/sub 2/DBr complex, and (ii) under 300 K single-collision bulk conditions. The differences between the resulting OD distributions are modest, and the present results are similar to those of the analogous H + CO/sub 2/ system.

  8. Negative-ion production on carbon materials in hydrogen plasma: Influence of the carbon hybridization state and the hydrogen content on H-

    E-print Network

    Boyer, Edmond

    are exposed to low pressure hydrogen plasma in a 13.56 MHz plasma reactor. Relative yields of surface produced1 Negative-ion production on carbon materials in hydrogen plasma: Influence of the carbon, The Netherlands Key words: Negative-ions, hydrogen plasma, mass spectrometer, carbon materials, Negative

  9. Process for production of carbon monoxide and hydrogen

    Microsoft Academic Search

    1978-01-01

    Carbon monoxide and hydrogen are produced by spraying a mixture of molten sodium and\\/or potassium from one nozzle into a chamber maintained at a temperature of 650 to 850°C along with one or more separated sprays containing a slurry of carbon, water and carbon dioxide so that the various sprays contact each other in said hot chamber so constructed so

  10. Synthesis of selectively labeled histidine and its methylderivatives with deuterium, tritium, and carbon-14.

    PubMed

    Šamonina-Kosicka, J; Ka?ska, M

    2013-05-30

    Isotopologues of l-histidine and its N-methylderivatives labeled with deuterium and tritium at the 5-position in the imidazole ring were obtained using the isotope exchange method. The deuterium-labeled isotopologues [5-(2)H]-l-histidine, [5-(2)H]-N(?) -methyl-l-histidine, [5-(2)H]-N(?) -methyl-l-histidine, and [2,5-(2)H(2)]-l-histidine were synthesized by isotope exchange method carried out in a fully deuterated medium with. The same reaction conditions were applied to synthesize [5-(3)H]-N(?) -methyl-l-histidine, [5-(3)H]-N(?) -methyl-l-histidine, and [5-(3)H]-l-histidine with specific activity of 2.0, 5.0, and 2.6?MBq/mmol, respectively. The N(?) -[methyl-(14)C]-histamine was obtained with specific activity of 0.23?MBq/mmol in a one-step reaction by the direct methylation of histamine by [(14)C]iodomethane. PMID:24285411

  11. TENSILE TESTING OF CARBON STEEL IN HIGH PRESSURE HYDROGEN

    SciTech Connect

    Duncan, A; Thad Adams, T; Ps Lam, P

    2007-05-02

    An infrastructure of new and existing pipelines and systems will be required to carry and to deliver hydrogen as an alternative energy source under the hydrogen economy. Carbon and low alloy steels of moderate strength are currently used in hydrogen delivery systems as well as in the existing natural gas systems. It is critical to understand the material response of these standard pipeline materials when they are subjected to pressurized hydrogen environments. The methods and results from a testing program to quantify hydrogen effects on mechanical properties of carbon steel pipeline and pipeline weld materials are provided. Tensile properties of one type of steel (A106 Grade B) in base metal, welded and heat affected zone conditions were tested at room temperature in air and high pressure (10.34 MPa or 1500 psig) hydrogen. A general reduction in the materials ability to plastically deform was noted in this material when specimens were tested in hydrogen. Furthermore, the primary mode of fracture was changed from ductile rupture in air to cleavage with secondary tearing in hydrogen. The mechanical test results will be applied in future analyses to evaluate service life of the pipelines. The results are also envisioned to be part of the bases for construction codes and structural integrity demonstrations for hydrogen service pipeline and vessels.

  12. Hydrogen storage: a comparison of hydrogen uptake values in carbon nanotubes and modified charcoals

    NASA Astrophysics Data System (ADS)

    Miao, H.-Y.; Chen, G. R.; Chen, D. Y.; Lue, J. T.; Yu, M. S.

    2010-11-01

    We compared the hydrogen uptake weight percentages (wt.%) of different carbonized materials, before and after modification, for their application in hydrogen storage at room temperature. The Sievert's method [T.P. Blach, E. Mac, A. Gray, J. Alloys Compd. 446-447, 692 (2007)] was used to measure hydrogen uptake values on: (1) Taiwan bamboo charcoal (TBC), (2) white charcoal (WC), (3) single-walled carbon nanotubes (SWCNTs) bought from CBT Inc. and (4) homemade multi-walled carbon nanotubes (MWCNTs) grown on TBC. Modified samples were coated with a metal catalyst by dipping in KOH solutions of different concentrations and then activated in a high temperature oven (800 °C) under the atmospheric pressure of inert gas. The results showed that unmodified SWCNTs had superior uptake but that Taiwan bamboo charcoal, after modification, showed enhanced uptake comparable to the SWCNTs. Due to TBC's low cost and high mass production rate, they will be the key candidate for future hydrogen storage applications.

  13. Deuterium-tritium pulse propulsion with hydrogen as propellant and the entire space-craft as a gigavolt capacitor for ignition

    NASA Astrophysics Data System (ADS)

    Winterberg, F.

    2013-08-01

    A deuterium-tritium (DT) nuclear pulse propulsion concept for fast interplanetary transport is proposed utilizing almost all the energy for thrust and without the need for a large radiator: By letting the thermonuclear micro-explosion take place in the center of a liquid hydrogen sphere with the radius of the sphere large enough to slow down and absorb the neutrons of the DT fusion reaction, heating the hydrogen to a fully ionized plasma at a temperature of ˜105 K. By using the entire spacecraft as a magnetically insulated gigavolt capacitor, igniting the DT micro-explosion with an intense GeV ion beam discharging the gigavolt capacitor, possible if the space craft has the topology of a torus.

  14. Mass spectral characterization of ergot alkaloids by electrospray ionization, hydrogen/deuterium exchange, and multiple stage mass spectrometry: Usefulness of precursor ion scan experiments.

    PubMed

    Mohamed, Rayane; Gremaud, Eric; Tabet, Jean-Claude; Guy, Philippe A

    2006-01-01

    Six ergot alkaloids belonging to the lysergic acid derivatives (ergonovine (EGN) and methysergide hydrogen maleinate (MHM)) and peptide-type derivatives (ergocristine (EGR), ergotamine (EGT), ergocornine (EGC) and alpha-ergokryptine (EGK)) were studied by positive electrospray tandem mass spectrometry. The fragmentation mechanisms of these compounds were studied by collision-induced dissociation (CID) using triple quadrupole and ion trap mass spectrometers, and the nature of the major product ions further confirmed by hydrogen/deuterium (H/D) exchange experiments. A common abundant product ion at m/z 223 was characteristic of the two classes of ergot alkaloids. Therefore, a precursor ion scan of m/z 223 that triggers information data acquisition (IDA) in combination with CID experiments was used to identify other potential ergot alkaloids. Using this approach, it was possible to confirm the presence of ergosine, another peptide-type ergot alkaloid, in a rye flour extract at trace levels. PMID:16941545

  15. Investigation of the role of the micro-porous layer in polymer electrolyte fuel cells with hydrogen deuterium contrast neutron radiography.

    PubMed

    Cho, Kyu Taek; Mench, Matthew M

    2012-03-28

    In this study, the high resolution hydrogen-deuterium contrast radiography method was applied to elucidate the impact of the micro-porous layer (MPL) on water distribution in the porous fuel cell media. At the steady state, deuterium replaced hydrogen in the anode stream, and the large difference in neutron attenuation of the D(2)O produced at the cathode was used to track the produced water. It was found that the water content peaked in the cathode-side diffusion media (DM) for the cell without MPL, but with an MPL on the anode and cathode DM, the peak water amount was pushed toward the anode, resulting in a relatively flattened water profile through components and demonstrating a liquid barrier effect. Additionally, the dynamic water behavior in diffusion media was analyzed to understand the effect of a MPL and operating conditions. The water content in the DM changed with applied current, although there is a significant amount of residual liquid content that does not appear to be part of capillary channels. The effect of the MPL on irreducible saturation in DM and cell performance was also investigated. PMID:22337210

  16. A search for narrow states in the inclusive gamma ray spectra resulting from antiproton annihilations at rest in liquid hydrogen and deuterium

    SciTech Connect

    Graf, N.A.; Fero, M.; Gee, M. [and others

    1991-08-01

    The energy spectrum of gamma rays produced in proton-antiproton annihilation at rest in hydrogen and deuterium has been measured with good energy resolution and high statistics. The data were taken using the PS183 magnetic pair spectrometer at LEAR (CERN). A detailed search of the gamma spectrum yielded no evidence of gamma transitions to narrow states with widths consistent with the spectrometer resolution. In hydrogen, upper limits (95% CL) are obtained for the yield of narrow states of 2--5 {times} 10{sup {minus}4} for states below 1,700 MeV/c{sup 2}, and 5--10 {times} 10{sup {minus}4} for states between 1,700 and 1,800 MeV/c{sup 2}. In deuterium, the corresponding upper limits are, 1--7 {times} 10{sup {minus}3} for masses between 700 and 1,730 MeV/c{sup 2}, and 1--2 {times} 10{sup {minus}3} for masses between 1,750 and 1,835 MeV/c{sup 2}. These results contradict reports of the observation of narrow lines made by previous experiments. Valid pacs appear here.

  17. Dependence of implantation temperature on chemical behavior of energetic deuterium implanted into tungsten carbide

    NASA Astrophysics Data System (ADS)

    Igarashi, E.; Nishikawa, Y.; Nakahata, T.; Yoshikawa, A.; Oyaidzu, M.; Oya, Y.; Okuno, K.

    2007-06-01

    Dependence of implantation temperature on chemical behavior of energetic deuterium implanted into WC was investigated by TDS and XPS. 1.0 keV D2+ ions were implanted into WC samples at the implantation temperature range of 323-873 K. It was found that the deuterium retention decreased as the implantation temperature increased. Above 573 K, most of the retained deuterium was bound to C, which was less than 20% of the total D retention after D2+ implantation at 323 K. Above 673 K, C was segregated on the WC surface and some of the implanted deuterium was retained in the segregated carbon layer. Additionally, it can be said that the D retention in WC was much less than that in other carbon-related materials, such as graphite and SiC. Hydrogen isotope retention can be reduced significantly when WC is formed on a divertor surface as a redeposited layer.

  18. Using Elemental Ratios to Predict the Density of Organic Material Composed of Carbon, Hydrogen, and Oxygen

    E-print Network

    Using Elemental Ratios to Predict the Density of Organic Material Composed of Carbon, Hydrogen material composed of carbon, oxygen, and hydrogen using the elemental ratios O:C and H:C as input,8 Although the oxygen-to- carbon (O:C) and hydrogen-to-carbon (H:C) elemental ratios of the particle

  19. MECHANICAL TESTING OF CARBON STEEL IN HIGH PRESSURE HYDROGEN

    SciTech Connect

    Duncan, A

    2006-05-11

    The methods and interim results from a testing program to quantify hydrogen effects on mechanical properties of carbon steel pipeline and pipeline weld materials are provided. The scope is carbon steels commonly used for natural gas pipelines in the United States that are candidates for hydrogen service in the hydrogen economy. The mechanical test results will be applied in future analyses to evaluate service life of the pipelines. The results are also envisioned to be part of the bases for construction codes and structural integrity demonstrations for hydrogen service pipeline and vessels. Tensile properties of one type of steel (A106 Grade B) in base metal, welded and heat affected zone conditions were tested at room temperature in air and high pressure (1500 psig) hydrogen. A general reduction in the materials ability to plastically deform was noted in this material when specimens were tested in 1500 psig hydrogen. Furthermore, the primary mode of fracture was changed from ductile rupture in air to cleavage with secondary tearing in hydrogen. The mechanical test program will continue with tests to quantify the fracture behavior in terms of J-R curves for these materials at air and hydrogen pressure conditions.

  20. Assessing carbon and hydrogen isotopic fractionation of diesel fuel n-alkanes during progressive evaporation.

    PubMed

    Muhammad, Syahidah A; Hayman, Alan R; Van Hale, Robert; Frew, Russell D

    2015-01-01

    Compound-specific isotope analysis offers potential for fingerprinting of diesel fuels, however, possible confounding effects of isotopic fractionation due to evaporation need to be assessed. This study measured the fractionation of the stable carbon and hydrogen isotopes in n-alkane compounds in neat diesel fuel during evaporation. Isotope ratios were measured using a continuous flow gas chromatograph/isotope ratio mass spectrometer. Diesel samples were progressively evaporated at 24 ± 2°C for 21 days. Increasing depletion of deuterium in nC12-nC17 alkanes in the remaining liquid with increasing carbon chain length was observed. Negligible carbon isotope fractionation was observed. Preferential vaporization was measured for the shorter chain n-alkanes and the trend decreased with increasing chain length. The decrease in ?(2) H values indicates the preferential vaporization of the isotopically heavier species consistent with available quantitative data for hydrocarbons. These results are most important in the application of stable isotope technology to forensic analysis of diesel. PMID:25131396

  1. Methanation of gas streams containing carbon monoxide and hydrogen

    DOEpatents

    Frost, Albert C. (Congers, NY)

    1983-01-01

    Carbon monoxide-containing gas streams having a relatively high concentration of hydrogen are pretreated so as to remove the hydrogen in a recoverable form for use in the second step of a cyclic, essentially two-step process for the production of methane. The thus-treated streams are then passed over a catalyst to deposit a surface layer of active surface carbon thereon essentially without the formation of inactive coke. This active carbon is reacted with said hydrogen removed from the feed gas stream to form methane. The utilization of the CO in the feed gas stream is appreciably increased, enhancing the overall process for the production of relatively pure, low-cost methane from CO-containing waste gas streams.

  2. Enhanced hydrogen adsorption in boron substituted carbon nanospaces

    NASA Astrophysics Data System (ADS)

    Firlej, L.; Roszak, Sz.; Kuchta, B.; Pfeifer, P.; Wexler, Carlos

    2009-10-01

    Activated carbons are one of promising groups of materials for reversible storage of hydrogen by physisorption. However, the heat of hydrogen adsorption in such materials is relatively low, in the range of about 4-8 kJ/mol, which limits the total amount of hydrogen adsorbed at P =100 bar to ˜2 wt % at room temperature and ˜8 wt % at 77 K. To improve the sorption characteristics the adsorbing surfaces must be modified either by substitution of some atoms in the all-carbon skeleton by other elements, or by doping/intercalation with other species. In this letter we present ab initio calculations and Monte Carlo simulations showing that substitution of 5%-10% of atoms in a nanoporous carbon by boron atoms results in significant increases in the adsorption energy (up to 10-13.5 kJ/mol) and storage capacity (˜5 wt % at 298 K, 100 bar) with a 97% delivery rate.

  3. Hydrogen adsorption studies on single wall carbon nanotubes

    Microsoft Academic Search

    A. Ansón; M. A. Callejas; A. M. Benito; W. K. Maser; M. T. Izquierdo; B. Rubio; J. Jagiello; M. Thommes; J. B. Parra; M. T. Mart??nez

    2004-01-01

    Hydrogen adsorption data on as-grown and heat-treated single walled carbon nanotubes (SWNTs) obtained by a volumetric procedure using a Quantachrome Autosorb-1 equipment are presented. The amounts of hydrogen adsorbed at atmospheric pressure reach approximately 0.01 wt.% at 298 K and 1 wt.% at 77 K. The isosteric heat of adsorption has been calculated for both samples from H2 equilibrium adsorption

  4. Theoretical analysis of hydrogen spillover mechanism on carbon nanotubes.

    PubMed

    Juarez-Mosqueda, Rosalba; Mavrandonakis, Andreas; Kuc, Agnieszka B; Pettersson, Lars G M; Heine, Thomas

    2015-01-01

    The spillover mechanism of molecular hydrogen on carbon nanotubes in the presence of catalytically active platinum clusters was critically and systematically investigated by using density-functional theory. Our simulation model includes a Pt4 cluster for the catalyst nanoparticle and curved and planar circumcoronene for two exemplary single-walled carbon nanotubes (CNT), the (10,10) CNT and one of large diameter, respectively. Our results show that the H2 molecule dissociates spontaneously on the Pt4 cluster. However, the dissociated H atoms have to overcome a barrier of more than 2 eV to migrate from the catalyst to the CNT, even if the Pt4 cluster is at full saturation with six adsorbed and dissociated hydrogen molecules. Previous investigations have shown that the mobility of hydrogen atoms on the CNT surface is hindered by a barrier. We find that instead the Pt4 catalyst may move along the outer surface of the CNT with activation energy of only 0.16 eV, and that this effect offers the possibility of full hydrogenation of the CNT. Thus, although we have not found a low-energy pathway to spillover onto the CNT, we suggest, based on our calculations and calculated data reported in the literature, that in the hydrogen-spillover process the observed saturation of the CNT at hydrogen background pressure occurs through mobile Pt nanoclusters, which move on the substrate more easily than the substrate-chemisorbed hydrogens, and deposit or reattach hydrogens in the process. Initial hydrogenation of the carbon substrate, however, is thermodynamically unfavoured, suggesting that defects should play a significant role. PMID:25699250

  5. Theoretical analysis of hydrogen spillover mechanism on carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Juarez Mosqueda, Rosalba; Mavrandonakis, Andreas; Kuc, Agnieszka; Pettersson, Lars; Heine, Thomas

    2015-02-01

    The spillover mechanism of molecular hydrogen on carbon nanotubes in the presence of catalytically active platinum clusters was critically and systematically investigated by using density-functional theory. Our simulation model includes a Pt4 cluster for the catalyst nanoparticle and curved and planar circumcoronene for two exemplary single-walled carbon nanotubes (CNT), the (10,10) CNT and one of large diameter, respectively. Our results show that the H2 molecule dissociates spontaneously on the Pt4 cluster. However, the dissociated H atoms have to overcome a barrier of more than 2 eV to migrate from the catalyst to the CNT, even if the Pt4 cluster is at full saturation with six adsorbed and dissociated hydrogen molecules. Previous investigations have shown that the mobility of hydrogen atoms on the CNT surface is hindered by a barrier. We find that instead the Pt4 catalyst may move along the outer surface of the CNT with activation energy of only 0.16 eV, and that this effect offers the possibility of full hydrogenation of the CNT. Thus, although we have not found a low-energy pathway to spillover onto the CNT, we suggest, based on our calculations and calculated data reported in the literature, that in the hydrogen-spillover process the observed saturation of the CNT at hydrogen background pressure occurs through mobile Pt nanoclusters, which move on the substrate more easily than the substrate-chemisorbed hydrogens, and deposit or reattach hydrogens in the process. Initial hydrogenation of the carbon substrate, however, is thermodynamically unfavoured, suggesting that defects should play a significant role.

  6. Theoretical analysis of hydrogen spillover mechanism on carbon nanotubes

    PubMed Central

    Juarez-Mosqueda, Rosalba; Mavrandonakis, Andreas; Kuc, Agnieszka B.; Pettersson, Lars G. M.; Heine, Thomas

    2015-01-01

    The spillover mechanism of molecular hydrogen on carbon nanotubes in the presence of catalytically active platinum clusters was critically and systematically investigated by using density-functional theory. Our simulation model includes a Pt4 cluster for the catalyst nanoparticle and curved and planar circumcoronene for two exemplary single-walled carbon nanotubes (CNT), the (10,10) CNT and one of large diameter, respectively. Our results show that the H2 molecule dissociates spontaneously on the Pt4 cluster. However, the dissociated H atoms have to overcome a barrier of more than 2 eV to migrate from the catalyst to the CNT, even if the Pt4 cluster is at full saturation with six adsorbed and dissociated hydrogen molecules. Previous investigations have shown that the mobility of hydrogen atoms on the CNT surface is hindered by a barrier. We find that instead the Pt4 catalyst may move along the outer surface of the CNT with activation energy of only 0.16 eV, and that this effect offers the possibility of full hydrogenation of the CNT. Thus, although we have not found a low-energy pathway to spillover onto the CNT, we suggest, based on our calculations and calculated data reported in the literature, that in the hydrogen-spillover process the observed saturation of the CNT at hydrogen background pressure occurs through mobile Pt nanoclusters, which move on the substrate more easily than the substrate-chemisorbed hydrogens, and deposit or reattach hydrogens in the process. Initial hydrogenation of the carbon substrate, however, is thermodynamically unfavoured, suggesting that defects should play a significant role. PMID:25699250

  7. Quantitative Analysis of Hydrogen in Amorphous Films of Hydrogenated Carbon Nitride

    NASA Astrophysics Data System (ADS)

    Ohkawara, Yoshiaki; Ohshio, Shigeo; Suzuki, Tsuneo; Ito, Haruhiko; Yatsui, Kiyoshi; Saitoh, Hidetoshi

    2001-12-01

    The amorphous phase of hydrogenated carbon nitride, a-CNx:H (0 ?q x ?q 1), films may have clusters consisting of a mixture of sp2- and sp3-hybridized materials with cluster sizes of 0.2-2 nm. The hydrogen termination limits the size of the carbon and carbon nitride clusters. It also influences the mechanical properties of the sample. In this experiment, the relationship between the hydrogen content and the mechanical properties of carbon and related materials was investigated using elastic recoil detection analysis (ERDA), nanoindentation techniques and Raman spectroscopy. The samples were classified into three categories of hardness: mechanically soft a-CNx:H (hardness: 1-8 GPa), mechanically hard a-CNx:H (8-30 GPa) and hard hydrogenated amorphous carbon (a-C:H) (more than 30 GPa). The hydrogen contents of the sample were 10-50 at.%, 5-40 at.%, and less than 3 at.% for soft a-CNx:H, hard a-CNx:H and hard a-C:H, respectively.

  8. Material processing with hydrogen and carbon monoxide on Mars

    NASA Technical Reports Server (NTRS)

    Hepp, Aloysius F.; Landis, Geoffrey A.; Linne, Diane L.

    1991-01-01

    Several novel proposals are examined for propellant production from carbon dioxide and monoxide and hydrogen. Potential uses were also examined of CO as a fuel or as a reducing agent in metal oxide processing as obtained or further reduced to carbon. Hydrogen can be reacted with CO to produce a wide variety of hydrocarbons, alcohols, and other organic compounds. Methanol, produced by Fischer-Tropsch chemistry may be useful as a fuel; it is easy to store and handle because it is a liquid at Mars temperatures. The reduction of CO2 to hydrocarbons such as methane or acetylene can be accomplished with hydrogen. Carbon monoxide and hydrogen require cryogenic temperatures for storage as liquids. Noncryogenic storage of hydrogen may be accomplished using hydrocarbons, inorganic hydrides, or metal hydrides. Noncryogenic storage of CO may be accomplished in the form of iron carbonyl (FE(CO)5) or other metal carbonyls. Low hydrogen content fuels such as acetylene (C2H2) may be effective propellants with low requirements for earth derived resources. The impact on manned Mars missions of alternative propellant production and utilization is discussed.

  9. Nanopores of carbon nanotubes as practical hydrogen storage media

    SciTech Connect

    Han, Sang Soo; Kim, Hyun Seok; Han, Kyu Sung; Lee, Jai Young; Lee, Hyuck Mo; Kang, Jeung Ku; Woo, Seong Ihl; Duin, Adri C.T. van; Goddard, William A. III [Department of Materials Science and Engineering, KAIST, Daejeon 305-701 (Korea, Republic of); Department of Chemical and Biomolecular Engineering, KAIST, Daejeon 305-701 (Korea, Republic of); Materials and Process Simulation Center, California Institute of Technology, California 91125 (United States)

    2005-11-21

    We report on hydrogen desorption mechanisms in the nanopores of multiwalled carbon nanotubes (MWCNTs). The as-grown MWCNTs show continuous walls that do not provide sites for hydrogen storage under ambient conditions. However, after treating the nanotubes with oxygen plasma to create nanopores in the MWCNTs, we observed the appearance of a new hydrogen desorption peak in the 300-350 K range. Furthermore, the calculations of density functional theory and molecular dynamics simulations confirmed that this peak could be attributed to the hydrogen that is physically adsorbed inside nanopores whose diameter is approximately 1 nm. Thus, we demonstrated that 1 nm nanopores in MWCNTs offer a promising route to hydrogen storage media for onboard practical applications.

  10. 40 CFR 415.330 - Applicability; description of the carbon monoxide and by-product hydrogen production subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...of the carbon monoxide and by-product hydrogen production subcategory. 415.330...CATEGORY Carbon Monoxide and By-Product Hydrogen Production Subcategory § 415.330...of the carbon monoxide and by-product hydrogen production subcategory. The...

  11. Inelastic Neutron Scattering from Hydrogen Adsorbed in Carbon

    NASA Astrophysics Data System (ADS)

    Olsen, Raina; Beckner, Matthew; Taub, Haskell; Pfeifer, Peter; Wexler, Carlos

    2011-03-01

    Inelastic neutron scattering (INS) from adsorbed hydrogen offers a powerful tool to probe the local adsorption environment of storage material. We will show recently measured INS spectra of hydrogen adsorbed on four different carbon samples and discuss the interpretation of their spectral features, using previous theoretical calculations. Both rotational and vibrational transitions can be observed, along with free recoil scattering parallel to the adsorption plane. The spectra from carbon nanotubes and activated carbon are well explained by theory. However, the spectra from PVDC carbon is quite unusual. This material is based upon work supported in part by the Department of Energy under Award Nos. DE-FG02-07ER46411, DE-FG36-08GO18142, and DE-AC02-06CH11357.

  12. Deuterium abundances

    E-print Network

    M. Lemoine; J. Audouze; L. Ben Jaffel; P. Feldman; R. Ferlet; G. Hebrard; E. B. Jenkins; C. Mallouris; W. Moos; K. Sembach; G. Sonneborn; A. Vidal-Madjar; D. G. York

    1999-03-02

    We discuss the measurements of deuterium abundances in high redshift quasar absorbers, in the solar system and in the interstellar medium. We present new results that indicate spatial variations of the deuterium abundance in the interstellar medium at the level of 50% over scales possibly as small as 10 pc, and discuss plausible causes for the origin of these variations.

  13. Carbon erosion in hydrogen---The midband'' problem revisited

    SciTech Connect

    Barletta, R.E.; Vanier, P.E.; Adams, J.W.; Svandrlik, J.F. (Reactor Systems Division, Department of Nuclear Energy, Brookhaven National Laboratory, Upton, New York 11973 (United States))

    1993-01-10

    Isothermal experiments were performed on TaC-coated carbon-carbon in flowing hydrogen at atmospheric pressure. Considerable effort was put into trying to detect an enhanced rate of erosion at intermediate temperatures ([similar to]1400 K) as was found in the NERVA program. No such enhancement ( midband corrosion'') was observed, and the temperature dependence of the reaction rates seemed to follow simple activated behavior consistent with a single rate-limiting process.

  14. Carbon erosion in hydrogen—The ``midband'' problem revisited

    NASA Astrophysics Data System (ADS)

    Barletta, Robert E.; Vanier, Peter E.; Adams, Jay W.; Svandrlik, John F.

    1993-01-01

    Isothermal experiments were performed on TaC-coated carbon-carbon in flowing hydrogen at atmospheric pressure. Considerable effort was put into trying to detect an enhanced rate of erosion at intermediate temperatures (˜1400 K) as was found in the NERVA program. No such enhancement (``midband corrosion'') was observed, and the temperature dependence of the reaction rates seemed to follow simple activated behavior consistent with a single rate-limiting process.

  15. Synthesis of carbon-14, carbon-13 and deuterium labeled forms of thioacetamide and thioacetamide S-oxide

    PubMed Central

    Sarma, Diganta; Hanzlik, Robert P.

    2013-01-01

    Thioacetamide (TA) is a model hepatotoxin that undergoes metabolic activation via two successive S-oxidations. The ultimate toxic metabolite thioacetamide S,S-dioxide, or its tautomer acetimidoyl sulfinic acid CH3C(NH)SO2H, then acylates lysine side chains on cellular proteins leading to cellular dysfunction or death. To identify individual target proteins, quantitate the extent of their modification and elucidate the structural details of their modification we required both radio-labeled and stable-labeled forms of TA and its intermediate metabolite thioacetamide S-oxide (TASO). The latter is stable when purified but can be difficult to isolate. Considering currently available isotopic precursors we devised and report here methods for the synthesis and isolation of TA and TASO labeled with C-14, C-13 and/or deuterium. The methods are straightforward, utilize readily available precursors and are amenable to small scale.

  16. Predicting Protein Aggregation during Storage in Lyophilized Solids Using Solid State Amide Hydrogen/Deuterium Exchange with Mass Spectrometric Analysis (ssHDX-MS)

    PubMed Central

    2015-01-01

    Solid state amide hydrogen/deuterium exchange with mass spectrometric analysis (ssHDX-MS) was used to assess the conformation of myoglobin (Mb) in lyophilized formulations, and the results correlated with the extent of aggregation during storage. Mb was colyophilized with sucrose (1:1 or 1:8 w/w), mannitol (1:1 w/w), or NaCl (1:1 w/w) or in the absence of excipients. Immediately after lyophilization, samples of each formulation were analyzed by ssHDX-MS and Fourier transform infrared spectroscopy (FTIR) to assess Mb conformation, and by dynamic light scattering (DLS) and size exclusion chromatography (SEC) to determine the extent of aggregation. The remaining samples were then placed on stability at 25 °C and 60% RH or 40 °C and 75% RH for up to 1 year, withdrawn at intervals, and analyzed for aggregate content by SEC and DLS. In ssHDX-MS of samples immediately after lyophilization (t = 0), Mb was less deuterated in solids containing sucrose (1:1 and 1:8 w/w) than in those containing mannitol (1:1 w/w), NaCl (1:1 w/w), or Mb alone. Deuterium uptake kinetics and peptide mass envelopes also indicated greater Mb structural perturbation in mannitol, NaCl, or Mb-alone samples at t = 0. The extent of deuterium incorporation and kinetic parameters related to rapidly and slowly exchanging amide pools (Nfast, Nslow), measured at t = 0, were highly correlated with the extent of aggregation on storage as measured by SEC. In contrast, the extent of aggregation was weakly correlated with FTIR band intensity and peak position measured at t = 0. The results support the use of ssHDX-MS as a formulation screening tool in developing lyophilized protein drug products. PMID:24816133

  17. Material processing with hydrogen and carbon monoxide on Mars

    NASA Technical Reports Server (NTRS)

    Hepp, Aloysius F.; Linne, Diane L.; Landis, Geoffrey A.

    1991-01-01

    Several novel proposals are examined for propellant production from carbon dioxide and monoxide and hydrogen. Potential uses were also examined of CO as a fuel or as a reducing agent in metal oxide processing as obtained or further reduced to carbon. Hydrogen can be reacted with CO to produce a wide variety of hydrocarbons, alcohols, and other organic compounds. Methanol, produced by Fischer-Tropsch chemistry may be useful as a fuel; it is easy to store and handle because it is a liquid at Mars temperatures. The reduction of CO2 to hydrocarbons such as methane or acetylene can be accomplished with hydrocarbons. Carbon monoxide and hydrogen require cryogenic temperatures for storage as liquid. Noncryogenic storage of hydrogen may be accomplished using hydrocarbons, inorganic hydrides, or metal hydrides. Noncryogenic storage of CO may be accomplished in the form of iron carbonyl (FE(CO)5) or other metal carbonyls. Low hydrogen content fuels such as acetylene (C2H2) may be effective propellants with low requirements for earth derived resources. The impact on manned Mars missions of alternative propellant production and utilization is discussed.

  18. Properties Of Plasma-Deposited Amorphous Hydrogenated Carbon

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Pouch, John J.; Alterovitz, Samuel A.

    1992-01-01

    Report reviews experimental research on plasma-deposited films of hydrogenated amorphous carbon. Such films exhibit electrical resistivity, semi-transparency, mechanical hardness, and chemical inertness. Useful as gate dielectrics and passivating layers in semiconductor devices, insulators for metal/insulator/metal devices, and masks in nanometer lithography. Show promise as wear-resistant, hard solid lubricating coats for bearings and optical components.

  19. Hydrogen passivation induced dispersion of multi-walled carbon nanotubes.

    PubMed

    Yang, Yingchao; Xu, Zhi-Hui; Pan, Zhengwei; Li, Xiaodong

    2012-02-14

    A method combining hydrogen passivation and ultrasonication was developed for the first time to disperse multi-walled carbon nanotubes (MWCNTs) in ethanol solution and epoxy resin. Excellent dispersion of MWCNTs was achieved in both media. Three-point bending tests of the MWCNT/epoxy nanocomposites revealed a remarkable increase in elastic modulus with increasing MWCNT content. PMID:22250052

  20. Hydrogen storage properties of catalyst metal-doped single-walled carbon nanotubes

    Microsoft Academic Search

    Yong-Won Lee

    2007-01-01

    In the past decade, hydrogen storage in solid-state materials has been one of the biggest hurdles to meet the storage density, safety, reliability and cost reduction needed for a hydrogen fuel economy. Single-walled carbon nanotubes (SWNTs) are particularly intriguing for hydrogen storage because each carbon atom is a surface site, and calculations have indicated that hydrogen bond strength can be

  1. Hydrogen-deuterium exchange mass spectrometry reveals the interaction of Fenna-Matthews-Olson protein and chlorosome CsmA protein

    PubMed Central

    Huang, Richard Y-C.; Wen, Jianzhong; Blankenship, Robert E.; Gross, Michael L.

    2011-01-01

    In green-sulfur bacterial photosynthesis, excitation energy absorbed by a peripheral antenna structure known as the chlorosome is sequentially transferred through a baseplate protein to the Fenna-Matthews-Olson (FMO) antenna protein and into the reaction center, which is embedded in the cytoplasmic membrane. The molecular details of the optimized photosystem architecture required for efficient energy transfer are only partially understood. We address here the question of how the baseplate interacts with the FMO protein by applying hydrogen/deuterium exchange coupled with enzymatic digestion and mass spectrometry analysis to reveal the binding interface of the FMO antenna protein and the CsmA baseplate protein. Several regions on the FMO protein, represented by peptides consisting of 123-129, 140-149, 150-162, 191-208 and 224-232, show significant decreases of deuterium uptake after CsmA binding. The results indicate that the CsmA protein interacts with the Bchl a #1 side of the FMO protein. A global picture including peptide-level details for the architecture of the photosystem from green sulfur bacteria can now be drawn. PMID:22142245

  2. Probing the Conformational and Functional Consequences of Disulfide Bond Engineering in Growth Hormone by Hydrogen-Deuterium Exchange Mass Spectrometry Coupled to Electron Transfer Dissociation.

    PubMed

    Seger, Signe T; Breinholt, Jens; Faber, Johan H; Andersen, Mette D; Wiberg, Charlotte; Schjødt, Christine B; Rand, Kasper D

    2015-06-16

    Human growth hormone (hGH), and its receptor interaction, is essential for cell growth. To stabilize a flexible loop between helices 3 and 4, while retaining affinity for the hGH receptor, we have engineered a new hGH variant (Q84C/Y143C). Here, we employ hydrogen-deuterium exchange mass spectrometry (HDX-MS) to map the impact of the new disulfide bond on the conformational dynamics of this new hGH variant. Compared to wild type hGH, the variant exhibits reduced loop dynamics, indicating a stabilizing effect of the introduced disulfide bond. Furthermore, the disulfide bond exhibits longer ranging effects, stabilizing a short ?-helix quite distant from the mutation sites, but also rendering a part of the ?-helical hGH core slightly more dynamic. In the regions where the hGH variant exhibits a different deuterium uptake than the wild type protein, electron transfer dissociation (ETD) fragmentation has been used to pinpoint the residues responsible for the observed differences (HDX-ETD). Finally, by use of surface plasmon resonance (SPR) measurements, we show that the new disulfide bond does not compromise receptor affinity. Our work highlight the analytical potential of HDX-ETD combined with functional assays to guide protein engineering. PMID:25978680

  3. Atypical Hydrogen Uptake on Chemically Activated, Ultramicroporous Carbon

    SciTech Connect

    Bhat, Vinay V [ORNL; Contescu, Cristian I [ORNL; Gallego, Nidia C [ORNL; Baker, Frederick S [ORNL

    2010-01-01

    Hydrogen adsorption at near-ambient temperatures on ultramicroporous carbon (UMC), derived through secondary chemical activation from a wood-based activated carbon was studied using volumetric and gravimetric methods. The results showed that physisorption is accompanied by a process of different nature that causes slow uptake at high pressures and hysteresis on desorption. In combination, this results in unusually high levels of hydrogen uptake at near-ambient temperatures and pressures (e.g. up to 0.8 wt % at 25 oC and 2 MPa). The heat of adsorption corresponding to the slow process leading to high uptake (17 20 kJ/mol) is higher than usually reported for carbon materials, but the adsorption kinetics is slow, and the isotherms exhibit pronounced hysteresis. These unusual properties were attributed to contributions from polarization-enhanced physisorption caused by traces of alkali metals residual from chemical activation. The results support the hypothesis that polarization-induced physisorption in high surface area carbons modified with traces of alkali metal ions is an alternate route for increasing the hydrogen storage capacity of carbon adsorbents.

  4. Stable Hydrogen and Carbon Isotope Fractionation during Microbial Toluene Degradation: Mechanistic and Environmental Aspects†

    PubMed Central

    Morasch, Barbara; Richnow, Hans H.; Schink, Bernhard; Meckenstock, Rainer U.

    2001-01-01

    Primary features of hydrogen and carbon isotope fractionation during toluene degradation were studied to evaluate if analysis of isotope signatures can be used as a tool to monitor biodegradation in contaminated aquifers. D/H hydrogen isotope fractionation during microbial degradation of toluene was measured by gas chromatography. Per-deuterated toluene-d8 and nonlabeled toluene were supplied in equal amounts as growth substrates, and kinetic isotope fractionation was calculated from the shift of the molar ratios of toluene-d8 and nondeuterated toluene. The D/H isotope fractionation varied slightly for sulfate-reducing strain TRM1 (slope of curve [b] = ?1.219), Desulfobacterium cetonicum (b = ?1.196), Thauera aromatica (b = ?0.816), and Geobacter metallireducens (b = ?1.004) and was greater for the aerobic bacterium Pseudomonas putida mt-2 (b = ?2.667). The D/H isotope fractionation was 3 orders of magnitude greater than the 13C/12C carbon isotope fractionation reported previously. Hydrogen isotope fractionation with nonlabeled toluene was 1.7 and 6 times less than isotope fractionation with per-deuterated toluene-d8 and nonlabeled toluene for sulfate-reducing strain TRM1 (b = ?0.728) and D. cetonicum (b = ?0.198), respectively. Carbon and hydrogen isotope fractionation during toluene degradation by D. cetonicum remained constant over a growth temperature range of 15 to 37°C but varied slightly during degradation by P. putida mt-2, which showed maximum hydrogen isotope fractionation at 20°C (b = ?4.086) and minimum fractionation at 35°C (b = ?2.138). D/H isotope fractionation was observed only if the deuterium label was located at the methyl group of the toluene molecule which is the site of the initial enzymatic attack on the substrate by the bacterial strains investigated in this study. Use of ring-labeled toluene-d5 in combination with nondeuterated toluene did not lead to significant D/H isotope fractionation. The activity of the first enzyme in the anaerobic toluene degradation pathway, benzylsuccinate synthase, was measured in cell extracts of D. cetonicum with an initial activity of 3.63 mU (mg of protein)?1. The D/H isotope fractionation (b = ?1.580) was 30% greater than that in growth experiments with D. cetonicum. Mass spectroscopic analysis of the product benzylsuccinate showed that H atoms abstracted from the toluene molecules by the enzyme were retained in the same molecules after the product was released. Our findings revealed that the use of deuterium-labeled toluene was appropriate for studying basic features of D/H isotope fractionation. Similar D/H fractionation factors for toluene degradation by anaerobic bacteria, the lack of significant temperature dependence, and the strong fractionation suggest that analysis of D/H fractionation can be used as a sensitive tool to assess degradation activities. Identification of the first enzyme reaction in the pathway as the major fractionating step provides a basis for linking observed isotope fractionation to biochemical reactions. PMID:11571192

  5. Comparing hardness and wear data for tetrahedral amorphous carbon and hydrogenated amorphous carbon thin films

    Microsoft Academic Search

    P. Lemoine; J. P. Quinn; P. Maguire; J. A. McLaughlin

    2004-01-01

    We compared nanoindentation and nanoscratch testing of 10 and 50nm thick tetrahedral amorphous carbon (ta-C) and hydrogenated amorphous carbon (a-C:H). Raman spectroscopy shows the expected spectral features for the two carbon forms, however, luminescence from the ceramic substrate can alter the spectra. We find that hard ta-C films can blunt the diamond tip and hence use a tip area function

  6. Shock compression of precompressed deuterium

    SciTech Connect

    Armstrong, M R; Crowhurst, J C; Zaug, J M; Bastea, S; Goncharov, A F; Militzer, B

    2011-07-31

    Here we report quasi-isentropic dynamic compression and thermodynamic characterization of solid, precompressed deuterium over an ultrafast time scale (< 100 ps) and a microscopic length scale (< 1 {micro}m). We further report a fast transition in shock wave compressed solid deuterium that is consistent with the ramp to shock transition, with a time scale of less than 10 ps. These results suggest that high-density dynamic compression of hydrogen may be possible on microscopic length scales.

  7. [Microbial synthesis of deuterium labelled L-phenylalanine with different levels of isotopic enrichment by facultative methylotrophic bacterium Brevibacterium methylicum with RMP assimilation of carbon].

    PubMed

    Mosin, O V; Shvets, V I; Skladnev, D A; Ignatov, I

    2014-01-01

    The preparative microbial synthesis of amino acids labelled with stable isotopes, including deuterium ( 2 H), suitable for biomedical applications by methylotrophic bacteria was studied using L-phenylalanine as example. This amino acid is secreted by Gram-negative aerobic facultative methylotrophic bacteria Brevibacterium methylicum, assimilating methanol via ribulose-5-monophosphate (RMP) cycle of assimilation of carbon, The data on adaptation of L-phenylalanine secreted by methylotrophic bacterium ?. methylicum to the maximal concentration of deuterium in the growth medium with 98% 2 ? 2 O and 2% [ 2 ?]methanol, and biosynthesis of deuterium labelled L-phenylalanine With different levels of enrichment are presented. The strain was adapted by means of plating initial cells on firm (2% agarose) minimal growth media with an increasing gradient of 2 ? 2 O concentration from 0; 24.5; 49.0; 73.5 up to 98% 2 ? 2 O followed by subsequent selection of separate colonies stable to the action of 2 ? 2 O. These colonies were capable to produce L-phenylalanine. L-phenylalanine was extracted from growth medium by extraction with isopropanol with the subsequent crystallization in ethanol (output 0.65 g/l). The developed method of microbial synthesis allows to obtain deuterium labelled L-phenylalanine with different levels of isotopic enrichment, depending on concentration of 2 ? 2 O in growth media, from 17% (on growth medium with 24,5% 2 ? 2 O) up to 75% (on growth medium with 98% 2 ? 2 O) of deuterium in the molecule that is confirmed with the data of the electron impact (EI) mass- spectrometry analysis of methyl ethers of N-dimethylamino(naphthalene)-5-sulfochloride (dansyl) phenylalanine in these experimental conditions. PMID:25249528

  8. Hydrogenation of carbon-cluster cations with molecular hydrogen: implications for the growth of carbon-cluster molecules

    NASA Astrophysics Data System (ADS)

    Bohme, Diethard K.; Wlodek, Stanislaw

    1990-12-01

    Experimental results are reviewed for the hydrogenation and deuteration of carbon-cluster cations in the gas phase. Emphasis is given to reactivity measurements performed with Fourier trasform ion-cyclotron resonance (FTICR) spectrometry for large cluster ions derived from graphite and diamond by laser vaporization, and reactivity measurements performed with selected-ion flow tube (SIFT) mass spectrometry for small cluster ions derived from benzene by electron impact. New SIFT measurements are presented for reactivities of small cluster ions primarily produced from acyclic hydrocarbon molecules by electron impact. Attention is given to the insight provided by these reactivity measurements into the influence of the morphology of carbon-cluster cations on the efficiency of their hydrogenation and deuteration and on the growth of carbon-cluster molecules as it is perceived to occur in interstellar chemistry.

  9. Atomistic Simulation of Carbon Nanotube Ropes and Hydrogen Absorption

    NASA Astrophysics Data System (ADS)

    Li, Ju; Yip, Sidney; Fujiwara, Joshua

    2001-06-01

    Atomistic Simulation of Carbon Nanotube Ropes and Hydrogen Absorption Ju Li, Sidney Yip, Massachusetts Institute of Technology, Department of Nuclear Engineering, Cambridge, MA 02139; Joshua Fujiwara, Honda R&D Co., Ltd., Wako Research Center, JAPAN. Using Brenner type Reactive Empirical Bond Order (REBO) interatomic potentials, we perform atomistic simulations to calculate the optimized structures, tensile and bending strengths, and thermal conductivities of both straight and twisted single-walled nanotube ropes (bundles) where results from direct simulation are checked against those from the Green-Kubo linear response theory. Preliminary calculations are performed to study hydrogen absorption by SWNTs at room temperature and 77K.

  10. New weight-loss measurements of the chemical erosion yields of carbon materials under hydrogen ion bombardment

    NASA Astrophysics Data System (ADS)

    Balden, M.; Roth, J.

    2000-06-01

    Total erosion yields of graphite and carbon materials under hydrogen and deuterium bombardment measured with the weight-loss method are presented for ion energies between 15 eV and 8 keV in the temperature range 300 to above 1000 K. The temperature of the maximum of the chemical erosion increases from below 600 to above 850 K with ion energies from 15 to 300 eV. Chemical erosion yields obtained by weight-loss measurements exceed yields measured mass-spectrometrically always by a factor of about two. Collector experiments show that a fraction of the eroded particle sticks to walls and, therefore, reduces the yield measured by mass spectrometry. A synergistic effect of neutrals in the ion beam on the chemical erosion yield can be excluded.

  11. Sulfur and Hydrogen Isotope Anomalies in Meteorite Sulfonic Acids

    NASA Technical Reports Server (NTRS)

    Cooper, George W.; Thiemens, Mark H.; Jackson, Teresa L.; Chang, Sherwood

    1997-01-01

    Intramolecular carbon, hydrogen, and sulfur isotope ratios were measured on a homologous series of organic sulfonic acids discovered in the Murchison meteorite. Mass-independent sulfur isotope fractionations were observed along with high deuterium/hydrogen ratios. The deuterium enrichments indicate formation of the hydrocarbon portion of these compounds in a low-temperature environment that is consistent with that of interstellar clouds. Sulfur-33 enrichments observed in methanesulfonic acid could have resulted from gas-phase ultraviolet irradiation of a precursor, carbon disulfide. The source of the sulfonic acid precursors may have been the reactive interstellar molecule carbon monosulfide.

  12. Renewable hydrogen and carbon nanotubes from biodiesel waste glycerol.

    PubMed

    Wu, Chunfei; Wang, Zichun; Williams, Paul T; Huang, Jun

    2013-01-01

    In this report, we introduce a novel and commercially viable method to recover renewable hydrogen and carbon nanotubes from waste glycerol produced in the biodiesel process. Gas-phase catalytic reforming converts glycerol to clean hydrogen fuel and by replacing the problematical coke formed on the catalyst with high value carbon nanotubes, added value can be realised. Additional benefits of around 2.8 kg CNTs from the reforming of 1 tonne of glycerol and the production of 500 Nm(3) H2 could have a considerable impact on the economics of glycerol utilization. Thereby, the contribution of this research will be a significant step forward in solving a current major technical and economic challenge faced by the biofuels industry. PMID:24067754

  13. Renewable hydrogen and carbon nanotubes from biodiesel waste glycerol

    PubMed Central

    Wu, Chunfei; Wang, Zichun; Williams, Paul T.; Huang, Jun

    2013-01-01

    In this report, we introduce a novel and commercially viable method to recover renewable hydrogen and carbon nanotubes from waste glycerol produced in the biodiesel process. Gas-phase catalytic reforming converts glycerol to clean hydrogen fuel and by replacing the problematical coke formed on the catalyst with high value carbon nanotubes, added value can be realised. Additional benefits of around 2.8?kg CNTs from the reforming of 1 tonne of glycerol and the production of 500?Nm3 H2 could have a considerable impact on the economics of glycerol utilization. Thereby, the contribution of this research will be a significant step forward in solving a current major technical and economic challenge faced by the biofuels industry. PMID:24067754

  14. Catalytic carbon membranes for hydrogen production. Final report

    SciTech Connect

    Damle, A.S.; Gangwal, S.K.

    1992-01-01

    Commercial carbon composite microfiltration membranes may be modified for gas separation applications by providing a gas separation layer with pores in the 1- to 10-nm range. Several organic polymeric precursors and techniques for depositing a suitable layer were investigated in this project. The in situ polymerization technique was found to be the most promising, and pure component permeation tests with membrane samples prepared with this technique indicated Knudsen diffusion behavior. The gas separation factors obtained by mixed-gas permeation tests were found to depend strongly on gas temperature and pressure indicating significant viscous flow at high-pressure conditions. The modified membranes were used to carry out simultaneous water gas shift reaction and product hydrogen separation. These tests indicated increasing CO conversions with increasing hydrogen separation. A simple process model was developed to simulate a catalytic membrane reactor. A number of simulations were carried out to identify operating conditions leading to product hydrogen concentrations over 90 percent. (VC)

  15. Hydrogenated 5-carbon compound and method of making

    DOEpatents

    Elliott, Douglas C. (Richland, WA); Frye, John G. (Richland, WA)

    1999-01-01

    The present invention is based upon the surprising discovery that a 5-carbon compound selected from the group of 4-oxopentanoic acid, at least one lactone of 4-oxopentanoic acid, and combinations thereof, may be hydrogenated with a bimetallic catalyst of a noble metal in combination with a second metal and preserve the pendant methyl group. It was further unexpectedly discovered that the same conditions of bimetallic catalyst in the presence of hydrogen are useful for catalyzing the different intermediate reactions for example angelicalactone to gamma-valerolactone and gamma-valerolactone to 1,4-pentanediol. Finally, it was surprising that levulinic acid could be converted to 2-methyltetrahydrofuran with heating in the presence of the bimetallic catalyst and hydrogen in a single process vessel. The method of the present invention unexpectedly produced a fuel or fuel component having 2-methyltetrahydrofuran either in a yield greater than 4.5 mol % or in combination with alcohols.

  16. Infrared emission from hydrogenated amorphous carbon and amorphous carbon grains in the interstellar medium

    NASA Technical Reports Server (NTRS)

    Duley, W. W.; Jones, A. P.; Taylor, S. D.; Williams, D. A.

    1993-01-01

    The correlations deduced by Boulanger et al. (1990) from IRAS maps of the Chamaeleon, Taurus and Ursa Major molecular cloud complexes are interpreted in terms of the evolutionary hydrogenated amorphous carbon model of interstellar dust. In particular, regions of relatively strong 12-micron emission may be regions where recently accreted carbon is being converted by ambient UV to small PAHs in situ. Regions of weak 12-micron emission are probably quiescent regions where carbon has been annealed to amorphous carbon. Observational consequences of these inferences are briefly described.

  17. Differentiating the role of lithium and oxygen in retaining deuterium on lithiated plasma-facing components

    NASA Astrophysics Data System (ADS)

    Taylor, Chase

    2013-10-01

    Lithium wall conditioning has been implemented in nearly a dozen fusion devices, resulting in significantly improved plasma performance. Improvements are manifest as a reduction and eventual elimination of edge localized modes, reduced edge neutral density, reduced deuterium recycling, and some reduction in impurities. Initially, researchers assumed that lithium, via a direct lithium-deuterium bond, was directly responsible for these improvements. Our experiments and atomistic simulations have revealed that lithium coatings play a much more indirect role in improving plasma performance. The presence of oxygen in tokamaks is ubiquitously viewed as unfavorable. However, recent results show that lithium reduces oxygen impurities and surprisingly uses the oxygen to retain deuterium. Experiments using X-ray photoelectron spectroscopy identify that oxygen immediately begins to accumulate on lithium conditioned surfaces. Tight-binding density functional theory simulations tested various carbon matrices with and without lithium, oxygen, and hydrogen, and identified that oxygen plays the key role in retaining deuterium. In fact, a simulated PFC with 20% oxygen in carbon retains more deuterium than does 20% lithium in carbon. Recent experiments implanted oxygen in graphite to match simulations; however, we were unable to achieve the simulated results because all implanted oxygen was released upon deuterium bombardment. We therefore conclude that while oxygen retains deuterium, lithium plays an indispensible role in this process. Lithium attracts and retains oxygen, and then oxygen binds and retains deuterium. Lithium wall conditioning has been implemented in nearly a dozen fusion devices, resulting in significantly improved plasma performance. Improvements are manifest as a reduction and eventual elimination of edge localized modes, reduced edge neutral density, reduced deuterium recycling, and some reduction in impurities. Initially, researchers assumed that lithium, via a direct lithium-deuterium bond, was directly responsible for these improvements. Our experiments and atomistic simulations have revealed that lithium coatings play a much more indirect role in improving plasma performance. The presence of oxygen in tokamaks is ubiquitously viewed as unfavorable. However, recent results show that lithium reduces oxygen impurities and surprisingly uses the oxygen to retain deuterium. Experiments using X-ray photoelectron spectroscopy identify that oxygen immediately begins to accumulate on lithium conditioned surfaces. Tight-binding density functional theory simulations tested various carbon matrices with and without lithium, oxygen, and hydrogen, and identified that oxygen plays the key role in retaining deuterium. In fact, a simulated PFC with 20% oxygen in carbon retains more deuterium than does 20% lithium in carbon. Recent experiments implanted oxygen in graphite to match simulations; however, we were unable to achieve the simulated results because all implanted oxygen was released upon deuterium bombardment. We therefore conclude that while oxygen retains deuterium, lithium plays an indispensible role in this process. Lithium attracts and retains oxygen, and then oxygen binds and retains deuterium. Work supported by USDOE Contracts DE-FG02-08ER54990 and DOE ID Field Office contract DE-AC07-05ID14517.

  18. Solution-phase deuterium/hydrogen exchange at a specific residue using nozzle-skimmer and electron capture dissociation mass spectrometry.

    PubMed

    Hagman, Charlotte; Tsybin, Yury O; Håkansson, Per

    2006-01-01

    Information about protein conformation can be obtained with hydrogen/deuterium exchange (HDX) mass spectrometry. The isotopic solution-phase exchange of specific amide hydrogen atoms can be followed using low-vacuum nozzle-skimmer collision-induced dissociation (CID). In this study, the nozzle-skimmer technique was complemented by electron capture dissociation (ECD) Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS). The solution-phase exchange at a specific residue is monitored by comparing isotopic distributions of two consecutive b- or c-type ions. While nozzle-skimmer fragmentation takes place in the low-vacuum region of the mass spectrometer, ECD occurs at ultra-high vacuum within the mass analyzer cell of the FTICR mass spectrometer. The dissociations take place at 10(-4) and 10(-9) mbar, respectively. Low-vacuum nozzle-skimmer fragmentation can result in intramolecular exchange between product ions and solvent molecules in the gas phase. Consequently, the solution-phase information about protein or peptide conformation is lost. It was not possible to monitor isotopic solution-phase exchange at the eighth residue in substance P, (Phe)8, with nozzle-skimmer CID. By using the in-cell ECD fragmentation method, the solution-phase exchange at the (Phe)8 residue was preserved during mass spectrometric analysis. This result shows the complementary aspects of applying fragmentation at low and at high vacuum, when studying isotopic exchange in solution at specific residues using FTICRMS. PMID:16447307

  19. Comment on ``Microwave attenuation of hydrogen plasma in carbon nanotubes''

    Microsoft Academic Search

    Afshin Moradi; Afshin

    2010-01-01

    In a recent article, Babaei and Solari [J. Appl. Phys. 104, 124315 (2008)] studied the effects of the electron temperature, and the external static magnetic field on the attenuation (ATT) of the microwave in the hydrogen plasma embedded inside the carbon nanotubes (CNTs), which were grown by iron-catalyzed high-pressure disproportionation (HiPco). They showed that the position of ATT peak shifts

  20. Photoluminescence and Raman spectroscopy in hydrogenated carbon films

    Microsoft Academic Search

    B. Marchon; Jing Gui; K. Grannen; G. C. Rauch; J. W. Ager III; S. R. P. Silva; J. Robertson

    1997-01-01

    a-C:H films prepared by DC-magnetron sputtering in an H-2:Ar mixture exhibit strong photoluminescence (PL) peaks superimposed upon the Raman scattering spectrum. PL becomes observable at a hydrogen content of ca. 34\\\\%, and increases exponentially thereafter, driven by the progressive saturation of carbon dangling bonds. In this \\\\%H range, hardness and elastic modulus decrease and CSS durability reaches an optimum. The

  1. Characterization of the International Humic Substances Society standard and reference fulvic and humic acids by solution state carbon-13 (13C) and hydrogen-1 (1H) nuclear magnetic resonance spectrometry

    USGS Publications Warehouse

    Thorn, Kevin A.; Folan, Daniel W.; MacCarthy, Patrick

    1989-01-01

    Standard and reference samples of the International Humic Substances Society have been characterized by solution state carbon-13 and hydrogen-1 nuclear magnetic resonance (NMR) spectrometry. Samples included the Suwannee River, soil, and peat standard fulvic and humic acids, the Leonardite standard humic acid, the Nordic aquatic reference fulvic and humic acids, and the Summit Hill soil reference humic acid. Aqueous-solution carbon-13 NMR analyses included the measurement of spin-lattice relaxation times, measurement of nuclear Overhauser enhancement factors, measurement of quantitative carbon distributions, recording of attached proton test spectra, and recording of spectra under nonquantitative conditions. Distortionless enhancement by polarization transfer carbon-13 NMR spectra also were recorded on the Suwannee River fulvic acid in deuterated dimethyl sulfoxide. Hydrogen-1 NMR spectra were recorded on sodium salts of the samples in deuterium oxide. The carbon aromaticities of the samples ranged from 0.24 for the Suwannee River fulvic acid to 0.58 for the Leonardite humic acid.

  2. Isotopic fractionation of carbon, deuterium and nitrogen : a full chemical study

    E-print Network

    Roueff, E; Hickson, K M

    2015-01-01

    Context. The increased sensitivity and high spectral resolution of millimeter telescopes allow the detection of an increasing number of isotopically substituted molecules in the interstellar medium. The 14N/ 15N ratio is difficult to measure directly for carbon containing molecules. Aims. We want to check the underlying hypothesis that the 13C/ 12C ratio of nitriles and isonitriles is equal to the elemental value via a chemical time dependent gas phase chemical model. Methods. We have built a chemical network containing D, 13C and 15N molecular species after a careful check of the possible fractionation reactions at work in the gas phase. Results. Model results obtained for 2 different physical conditions corresponding respectively to a moderately dense cloud in an early evolutionary stage and a dense depleted pre-stellar core tend to show that ammonia and its singly deuterated form are somewhat enriched in 15N, in agreement with observations. The 14N/ 15N ratio in N2H+ is found to be close to the elemental v...

  3. Nonuniform isotope patterns produced by collision-induced dissociation of homogeneously labeled ubiquitin: implications for spatially resolved hydrogen/deuterium exchange ESI-MS studies.

    PubMed

    Ferguson, Peter L; Konermann, Lars

    2008-06-01

    There is an ongoing debate whether collision-induced dissociation (CID) of electrosprayed proteins after solution-phase hydrogen/deuterium exchange (HDX) is a viable approach for determining spatially resolved deuteration patterns. This work explores the use of two methods, source-CID and hexapole tandem mass spectrometry (MS/MS) on a quadrupole time-of-flight (Q-TOF) mass spectrometer, for measuring the fragment deuteration levels of regioselectively labeled ubiquitin. Both methods reveal that b-ions exhibit HDX levels significantly below that of the intact protein, whereas several y'' fragments are labeled to a much greater extent. These results are consistent with earlier source-CID data (Akashi, S.; Naito, Y.; Takio, K. Anal. Chem. 1999, 71, 4974-4980). However, the measured b-ion deuteration levels are in disagreement with the known solution-phase behavior of ubiquitin. Partial agreement is observed for y''-ions. Control experiments on homogeneously labeled ubiquitin (having the same average deuteration level at every exchangeable site) result in highly nonuniform fragment HDX levels. In particular, b-ions exhibit deuteration levels significantly below that of intact ubiquitin, thereby mimicking the behavior seen for the regioselectively labeled protein. This effect is likely caused by isotope fractionation during collisional activation, facilitated by the high mobility of charge carriers (scrambling) in the gas phase. The observation that the b-ion labeling behavior is largely independent of the spatial isotope distribution within solution-phase ubiquitin invalidates these ions as reporters of the protein deuteration pattern. This work questions the common practice of interpreting any nonuniformities in fragment deuteration as being indicative of regioselective solution-phase labeling. Artifactual deuterium enrichment or depletion during collisional activation may have contributed to the current lack of consensus as to whether HDX/CID represents a potentially viable tool for measuring solution-phase deuteration patterns. PMID:18459737

  4. Atomic hydrogen interactions with amorphous carbon thin films Bhavin N. Jariwala,1

    E-print Network

    Ciobanu, Cristian

    Atomic hydrogen interactions with amorphous carbon thin films Bhavin N. Jariwala,1 Cristian V-scale interactions of H atoms with hydrogenated amorphous carbon a-C:H films were identified using molecular dynamics through a detailed analysis of the MD trajectories. The MD simulations showed that hydrogenation occurs

  5. Isotopic effect on the vibrational lifetime of the carbon-deuterium stretch excitation on graphene.

    PubMed

    Sakong, Sung; Kratzer, Peter

    2011-09-21

    The relaxation of vibrational energy in the H and D stretch modes has been studied on the graphene surface using ab initio calculations. The dissipation of the vibrational energy stored in the stretching modes proceeds through vibration-phonon coupling, while the dissipation through electronic excitations makes only minor contributions. Recently, we reported the fast relaxation of the H stretch energy on graphene [S. Sakong and P. Kratzer, J. Chem. Phys. 133, 054505 (2010)]. Interestingly, we predict the lifetime of the D stretch to be markedly longer compared to the relaxation of the H stretch. This is unexpected since the vibrational amplitudes at carbon atoms in the joint C-D vibrational modes are larger than in the joint C-H modes, due to the mass ratio m(D)/m(C) > m(H)/m(C). However, the vibrational relaxation rate for the D stretch is smaller than for the H stretch, because the energy is dissipated to an acoustic phonon of graphene in the case of C-D rather than an optical phonon as is the case in C-H, and hence, the corresponding phonon density of states is lower in the C-D case. To rationalize our findings, we propose a general scheme for estimating vibrational lifetimes of adsorbates based on four factors: the density of states of the phonons that mediates the transitions, the vibration-phonon coupling strength, the anharmonic coupling between local modes, and the number of quanta involved in the transitions. Mainly the first two of these factors are responsible for the differences in the lifetimes of the C-H and C-D stretches. The possible role of the other factors is illustrated in the context of vibrational lifetimes in other recently studied systems. PMID:21950870

  6. Formaldehyde metabolism by Escherichia coli. Carbon and solvent deuterium incorporation into glycerol, 1,2-propanediol, and 1,3-propanediol.

    PubMed

    Hunter, B K; Nicholls, K M; Sanders, J K

    1985-07-16

    Escherichia coli were grown on 14.3% uniformly 13C-labeled glucose as the sole carbon source and challenged anaerobically with 90% 13C-labeled formaldehyde. The major multiply labeled metabolites were identified by 13C NMR spectroscopy to be glycerol and 1,2-propanediol, and a minor metabolite was shown to be 1,3-propanediol. In each case, formaldehyde is incorporated only into the C1 position. A novel form of 13C NMR isotope dilution analysis of the major products reveals that all the 1,2-diol C1 is formaldehyde derived but that about 40% of the glycerol C1 is derived from bacterial sources. Glycerokinase converted the metabolite [1-13C]glycerol to equal amounts of [3-13C]glycerol 3-phosphate and [1-13C]glycerol 3-phosphate, demonstrating that the metabolite is racemic. When [13C]formaldehyde incubation was carried out in H2O/D2O mixtures, deuterium incorporation was detected by beta- and gamma-isotope shifts. The 1,3-diol is deuterium labeled only at C2 and only once, while the 1,2-diol and glycerol are each labeled independently at both C2 and C3; C3 is multiply labeled. Deuterium incorporation levels are different for each metabolite, indicating that the biosynthetic pathways probably diverge early. PMID:3902080

  7. Formaldehyde metabolism by Escherichia coli. Carbon and solvent deuterium incorporation into glycerol, 1,2-propanediol, and 1,3-propanediol

    SciTech Connect

    Hunter, B.K.; Nicholls, K.M.; Sanders, J.K.

    1985-07-16

    Escherichia coli were grown on 14.3% uniformly TC-labeled glucose as the sole carbon source and challenged anaerobically with 90% TC-labeled formaldehyde. The major multiply labeled metabolites were identified by TC NMR spectroscopy to be glycerol and 1,2-propanediol, and a minor metabolite was shown to be 1,3-propanediol. In each case, formaldehyde is incorporated only into the C1 position. A novel form of TC NMR isotope dilution analysis of the major products reveals that all the 1,2-diol C1 is formaldehyde derived but that about 40% of the glycerol C1 is derived from bacterial sources. Glycerokinase converted the metabolite (1- TC)glycerol to equal amounts of (3- TC)glycerol 3-phosphate and (1- TC)glycerol 3-phosphate, demonstrating that the metabolite is racemic. When ( TC)formaldehyde incubation was carried out in H2O/D2O mixtures, deuterium incorporation was detected by beta- and gamma-isotope shifts. The 1,3-diol is deuterium labeled only at C2 and only once, while the 1,2-diol and glycerol are each labeled independently at both C2 and C3; C3 is multiply labeled. Deuterium incorporation levels are different for each metabolite, indicating that the biosynthetic pathways probably diverge early.

  8. Corrosion of Carbon Steel in Carbon Dioxide-Saturated Solutions Containing Small Amounts of Hydrogen Sulfide

    Microsoft Academic Search

    K. Videm; J. Kvarekvaal

    1995-01-01

    Carbon steel specimens were exposed in carbon dioxide (COâ)-containing brine with different amounts of hydrogen sulfide (HâS) at 70 C and 80 C. The addition of 0.02 mmol\\/L sulfide, corresponding to 45 Pa HâS partial pressure (P{sub HâS}), to brine with 70 kPa COâ at pH 4.2 caused rapid formation of a protective corrosion film. After â¼ 15 min, the

  9. Structure of middle distillate fuels on the atomic carbon and hydrogen to carbon ratio at alpha position to aromatic rings

    SciTech Connect

    Glavincevski, B.; Gulder, O.L.; Gardner, L

    1988-01-01

    The alkyl, naphthenic, or total carbon atoms of the functional groups at alpha position to aromatic rings and their hydrogen to carbon ratio are some of the important parameters for structural analysis of fossil fuel products. In this paper, the authors present a number of novel formula-structure relationships for precise determination of different carbon atom types at alpha position to aromatic rings and the average number of hydrogens per alpha-carbon.

  10. Water electrolysis with a conducting carbon cloth: subthreshold hydrogen generation and superthreshold carbon quantum dot formation.

    PubMed

    Biswal, Mandakini; Deshpande, Aparna; Kelkar, Sarika; Ogale, Satishchandra

    2014-03-01

    A conducting carbon cloth, which has an interesting turbostratic microstructure and functional groups that are distinctly different from other ordered forms of carbon, such as graphite, graphene, and carbon nanotubes, was synthesized by a simple one-step pyrolysis of cellulose fabric. This turbostratic disorder and surface chemical functionalities had interesting consequences for water splitting and hydrogen generation when such a cloth was used as an electrode in the alkaline electrolysis process. Importantly, this work also gives a new twist to carbon-assisted electrolysis. During electrolysis, the active sites in the carbon cloth allow slow oxidation of its surface to transform the surface groups from C?OH to COOH and so forth at a voltage as low as 0.2?V in a two-electrode system, along with platinum as the cathode, instead of 1.23?V (plus overpotential), which is required for platinum, steel, or even graphite anodes. The quantity of subthreshold hydrogen evolved was 24?mL?cm(-2) ?h(-1) at 1?V. Interestingly, at a superthreshold potential (>1.23?V+overpotential), another remarkable phenomenon was found. At such voltages, along with the high rate and quantity of hydrogen evolution, rapid exfoliation of the tiny nanoscale (5-7?nm) units of carbon quantum dots (CQDs) are found in copious amounts due to an enhanced oxidation rate. These CQDs show bright-blue fluorescence under UV light. PMID:24492961

  11. Retention and enrichment of tungsten-containing carbon films under deuterium beam impact

    NASA Astrophysics Data System (ADS)

    Sauter, P. A.; Balden, M.

    2013-09-01

    Retention and enrichment of a model system for mixed layers, tungsten-containing carbon films (a-C:W), were investigated with respect to the interaction with D ions. a-C:W was exposed to a mass-separated, mono-energetic D beam (200 eV/D, 1.2 × 1015 D cm-2 s-1). The W concentration in the films (0-7.5 at.%), the specimen temperature during D beam exposure (300-1300 K) and the fluence (?) of incident D (1015-1020 D cm-2) were varied. Analysis of retention and enrichment were performed by nuclear reaction analysis and Rutherford backscattering spectrometry, respectively. At 300 K and fluences up to 1019 D cm-2, the increase of the D inventory with fluence in a-C:W cannot be distinguished from a-C and pyrolytic graphite, e.g., above ˜1017 D cm-2 the D inventory increases with fluence according to ?x (x = 0.1). Above a fluence of 1019 D cm-2, however, the D inventory depends strongly on the W concentration. At a fluence of 1020 D cm-2 the D inventory is increased to the 1.5-fold of the D inventory of pyrolytic graphite for 1% and 2.5% a-C:W and it is decreased to the half value of the D inventory of pyrolytic graphite for 7.5% a-C:W. At temperatures above 300 K, following trends are observed: With increasing temperature, the D inventory increases more strongly with fluence and D reaches depths far beyond the width of the ion range. However, the D inventory does not increase with fluence according to ?x, especially at fluences above 1019 D cm-2. The peak near the surface (<70 nm) in Fig. 2a, which was increasing with decreasing temperature, is caused by an accumulation of D at surface near zones, which can be reached by energetic D. This is interpreted in the following way: Bonding states with a lower binding energy than the thermal energy at 900 K, which were unoccupied before decreasing the temperature, were becoming occupied during the decrease of the temperature; the saturation level of the implantation zone is lowered at 900 K compared to 300 K. Before the decrease of the temperature, D was able to reach depths (?600 nm; Fig. 2a), which are beyond the peak near the surface and thus cannot be reached by energetic D. Consequently, it can be concluded that the tail to lower energies in the NRA spectrum is caused by a diffusive process of D into depth (˜90% of the total inventory), i.e., a-C:W allows a kind of diffusive transport of D into depths beyond the implantation zone. (Note that these depths will be denoted as the diffusion depth in the following.) Bonding states occupied at 900 K during beam exposure are not depleted after the exposure is stopped (Fig. 2b). This interpretation is confirmed by the release of D towards the surface after the heat treatment at 1300 K (Fig. 2c). Additional bonding states, which were occupied at 1100 K, were depleted raising the temperature above 1100 K. Heat treatment at 1100 K and at 1300 K (Fig. 2c) showed a diffusive transport of D, which is directed towards the surface without the presence of an impacting D beam. In other words, the presence of a D beam is a necessary condition for the diffusive transport of D into depth.

  12. Numerical Analysis of Hydrogen Storage in Carbon Nanopores

    NASA Astrophysics Data System (ADS)

    Wexler, Carlos; Olsen, Raina; Pfeifer, Peter; Kuctha, Bogdan; Firlej, Lucyna; Roszak, Sztepan

    Carbon-based materials, due to their low cost and weight, have long been considered as suitable physisorption substrates for the reversible storage of hydrogen. Nanoporous carbons can be engineered to achieve exceptional storage capacities: gravimetric excess adsorption of 0.073 ± 0.003 kg H2/kg carbon, gravimetric storage capacity of 0.106 ± 0.005 kg H2/kg carbon, and volumetric storage capacity of 0.040 ± 0.002 kg H2/liter carbon, at 80 K and 50 bar. The nanopores generage high storage capacity by having a very high surface are, by generating a high H2-wall interaction potential, and by allowing multi-layer adsorption of H2 (at cryogenic temperatures). In this paper we show how the experimental adsorption isotherms can be understood from basic theoretical considerations and computational simulations of the adsorption in a bimodal distribution of narrow and wide pore spaces. We also analyze the possibility of multi-layer adsorption, and the effects of hypothetical larger adsorption energies. Finally, we present the results of coupled ab initio calculations and Monte Carlo simulations showing that partial substitution of carbon atoms in nanoporous matrix with boron results in significant increases of the adsorption energy and storage capacity.

  13. Numerical Analysis of Hydrogen Storage in Carbon Nanopores

    NASA Astrophysics Data System (ADS)

    Wexler, Carlos; Olsen, Raina; Pfeifer, Peter; Kuctha, Bogdan; Firlej, Lucyna; Roszak, Sztepan

    2011-03-01

    Carbon-based materials, due to their low cost and weight, have long been considered as suitable physisorption substrates for the reversible storage of hydrogen. Nanoporous carbons can be engineered to achieve exceptional storage capacities: gravimetric excess adsorption of 0.073 ± 0.003 kg H2/kg carbon, gravimetric storage capacity of 0.106 ± 0.005 kg H2/kg carbon, and volumetric storage capacity of 0.040 ± 0.002 kg H2/liter carbon, at 80 K and 50 bar. The nanopores generage high storage capacity by having a very high surface are, by generating a high H2-wall interaction potential, and by allowing multi-layer adsorption of H2 (at cryogenic temperatures). In this paper we show how the experimental adsorption isotherms can be understood from basic theoretical considerations and computational simulations of the adsorption in a bimodal distribution of narrow and wide pore spaces. We also analyze the possibility of multi-layer adsorption, and the effects of hypothetical larger adsorption energies. Finally, we present the results of coupled ab initio calculations and Monte Carlo simulations showing that partial substitution of carbon atoms in nanoporous matrix with boron results in significant increases of the adsorption energy and storage capacity.

  14. Closed system Fischer-Tropsch synthesis over meteoritic iron, iron ore and nickel-iron alloy. [deuterium-carbon monoxide reaction catalysis

    NASA Technical Reports Server (NTRS)

    Nooner, D. W.; Gibert, J. M.; Gelpi, E.; Oro, J.

    1976-01-01

    Experiments were performed in which meteoritic iron, iron ore and nickel-iron alloy were used to catalyze (in Fischer-Tropsch synthesis) the reaction of deuterium and carbon monoxide in a closed vessel. Normal alkanes and alkenes and their monomethyl substituted isomers and aromatic hydrocarbons were synthesized. Iron oxide and oxidized-reduced Canyon Diablo used as Fischer-Tropsch catalysts were found to produce aromatic hydrocarbons in distributions having many of the features of those observed in carbonaceous chondrites, but only at temperatures and reaction times well above 300 C and 6-8 h.

  15. Kinetic effect of Pd additions on the hydrogen uptake of chemically activated, ultramicroporous carbon

    SciTech Connect

    Bhat, Vinay V [ORNL; Contescu, Cristian I [ORNL; Gallego, Nidia C [ORNL

    2010-01-01

    The effect of mixing chemically-activated ultramicroporous carbon (UMC) with Pd nanopowder is investigated. Results show that Pd addition doubles the rate of hydrogen uptake, but does not enhance the hydrogen capacity or improve desorption kinetics. The effect of Pd on the rate of hydrogen adsorption supports the occurrence of the hydrogen spillover mechanism in the Pd - UMC system.

  16. Structure and mechanical properties of hydrogenated carbon films prepared by magnetron sputtering [for magnetic discs

    Microsoft Academic Search

    B. Marchon; P. N. Vo; M. R. Khan

    1991-01-01

    Hydrogenated thin carbon films have been prepared by DC magnetron sputtering in a hydrogen-containing argon HD-09. A monotonic decrease in friction buildup as well as an increase in abrasion resistance is observed for increasing hydrogen addition to the argon atmosphere, from 0 to 5%. Raman data show higher sp3 character, and an increase in hydrogen content in the film, as

  17. Biochemical hydrogen isotope fractionation during biosynthesis in higher plants reflects carbon metabolism of the plant

    NASA Astrophysics Data System (ADS)

    Cormier, Marc-André; Kahmen, Ansgar

    2015-04-01

    Compound-specific isotope analyses of plant material are frequently applied to understand the response of plants to the environmental changes. As it is generally assume that the main factors controlling ?2H values in plants are the plant's source water and evaporative deuterium enrichment of leaf water, hydrogen isotope analyses of plant material are mainly applied regarding hydrological conditions at different time scales. However, only few studies have directly addressed the variability of the biochemical hydrogen isotope fractionation occurring during biosynthesis of organic compounds (É?bio), accounting also for a large part in the ?2H values of plants but generally assumed to be constant. Here we present the results from a climate-controlled growth chambers experiment where tested the sensitivity of É?bio to different light treatments. The different light treatments were applied to induce different metabolic status (autotrophic vs. heterotrophic) in 9 different plant species that we grew from large storage organs (e.g. tubers or roots). The results show a systematic É?bio shift (up to 80 ) between the different light treatments for different compounds (i.e. long chain n-alkanes and cellulose). We suggest that this shift is due to the different NADPH pools used by the plants to build up the compounds from stored carbohydrates in heterotrophic or autotrophic conditions. Our results have important implications for the calibration and interpretation of sedimentary and tree rings records in geological studies. In addition, as the ?2H values reflect also strongly the carbon metabolism of the plant, our findings support the idea of ?2H values as an interesting proxy for plant physiological studies.

  18. Hydrogen-Stimulated Gene Expression by Salmonella enterica serovar Typhimurium in a Carbon Limited Environment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: Salmonella enterica serovar Typhimurium can utilize molecular hydrogen for growth and amino acid transport during anaerobic growth in a carbon limited environment. In this study we identified hydrogen-stimulated gene expression changes contributing to Salmonella survival. Methods: Micr...

  19. Kinetics of the Reduction of Wüstite by Hydrogen and Carbon Monoxide for the Chemical Looping Production of Hydrogen

    E-print Network

    Liu, Wen; Lim, Jin Yang; Saucedo, Marco A.; Hayhurst, Allan N.; Scott, Stuart A.; Dennis, J. S.

    2014-08-13

    produced could be stored, e.g. by geological sequestration, making the overall process “carbon-neutral”, or “carbon-negative” when biomass is used as fuel. In addition, the hydrogen produced during the oxidation of FexO and metallic Fe in steam can be kept... Kinetics of the reduction of wüstite by hydrogen and carbon monoxide for the chemical looping production of hydrogen Wen Liu a,n, Jin Yang Lim b, Marco A. Saucedo a, Allan N. Hayhurst b, Stuart A. Scott a, J.S. Dennis b a Department of Engineering...

  20. Deuterium trapping in tungsten

    NASA Astrophysics Data System (ADS)

    Poon, Michael

    Tungsten is one of the primary material candidates being investigated for use in the first-wall of a magnetic confinement fusion reactor. An ion accelerator was used to simulate the type of ion interaction that may occur at a plasma-facing material. Thermal desorption spectroscopy (TDS) was the primary tool used to analyze the effects of the irradiation. Secondary ion mass spectroscopy (SIMS) was used to determine the distribution of trapped D in the tungsten specimen. The tritium migration analysis program (TMAP) was used to simulate thermal desorption profiles from the D depth distributions. Fitting of the simulated thermal desorption profiles with the measured TDS results provided values of the D trap energies. Deuterium trapping in single crystal tungsten was studied as a function of the incident ion fluence, ion flux, irradiation temperature, irradiation history, and surface impurity levels during irradiation. The results show that deuterium was trapped at vacancies and voids. Two deuterium atoms could be trapped at a tungsten vacancy, with trapping energies of 1.4 eV and 1.2 eV for the first and second D atoms, respectively. In a tungsten void, D is trapped as atoms adsorbed on the inner walls of the void with a trap energy of 2.1 eV, or as D2 molecules inside the void with a trap energy of 1.2 eV. Deuterium trapping in polycrystalline tungsten was also studied as a function of the incident fluence, irradiation temperature, and irradiation history. Deuterium trapping in polycrystalline tungsten also occurs primarily at vacancies and voids with the same trap energies as in single crystal tungsten; however, the presence of grain boundaries promotes the formation of large surface blisters with high fluence irradiations at 500 K. In general, D trapping is greater in polycrystalline tungsten than in single crystal tungsten. To simulate mixed materials comprising of carbon (C) and tungsten, tungsten specimens were pre-irradiated with carbon ions prior to D irradiation. Deuterium trapping could be characterized by three regimes: (i) enhanced D retention in a graphitic film formed by the C+ irradiation; (ii) decreased D retention in a modified tungsten-carbon layer; and (iii) D retention in pure tungsten.

  1. Carbide-Derived Carbons with Tunable Porosity Optimized for Hydrogen Storage

    Microsoft Academic Search

    John E. Fischer; Yury Gogotsi; Taner Yildirim

    2010-01-01

    On-board hydrogen storage is a key requirement for fuel cell-powered cars and trucks. Porous carbon-based materials can in principle adsorb more hydrogen per unit weight at room temperature than liquid hydrogen at -176 oC. Achieving this goal requires interconnected pores with very high internal surface area, and binding energies between hydrogen and carbon significantly enhanced relative to H2 on graphite.

  2. Toward Understanding of Hydrogen Storage in Single-Walled Carbon Nanotubes by Investigations of Chemisorption Mechanism

    Microsoft Academic Search

    T. C. Dinadayalane; Jerzy Leszczynski

    2010-01-01

    \\u000a We provide an overview of experimental and theoretical studies on hydrogen storage in single-walled carbon nanotubes (SWNTs)\\u000a via chemisorption mechanism. The atomic hydrogens that are generated by dissociation of H2 molecules bind with carbon atoms of nanotubes, leading to strong C–H bonds in the chemisorption process. Recent experimental\\u000a study indicates that 5.1?±?1.2 wt% hydrogen storage could be achieved by hydrogenation

  3. Adsorption of hydrogen in boron-substituted nanoporous carbons

    NASA Astrophysics Data System (ADS)

    Firlej, L.; Kuchta, B.; Roszak, S.; Pfeifer, P.; Wexler, C.

    2010-03-01

    Nanoporous carbons are promising for hydrogen storage. However, the heat of physisorption is low (4.5-8 kJ/mol), which limits the total amount of hydrogen adsorbed at room temperature to ˜2 wt.% at 100 bar. To enhance sorption the surface must be modified by substitution or doping/intercalation of some atoms in the carbon skeleton by other elements. Here we present coupled ab initio calculations and Monte Carlo simulations showing that partial substitution of carbon atoms in nanoporous matrix with boron increases significantly the adsorption energy (up to 10-13.5 kJ/mol) and storage capacity (˜5 wt.% at 298 K, 100 bar), even for relatively low substitution ratios (5-10%). Although substitution causes both energetic and structural heterogeneity of the adsorbent, at room temperature the delivery of the stored gas during adsorption-desorption cycle is almost complete (˜97 %). We analyze whether the location of substituted atoms (within the graphene plane or between two adjacent planes) and randomness of its distribution modify either the adsorption mechanism or/and storage parameters. In particular the heterogeneity of energy landscape is discussed in a context of optimization of system delivery.

  4. Conformational Dynamics of the Bovine Mitochondrial ADP/ATP Carrier Isoform 1 Revealed by Hydrogen/Deuterium Exchange Coupled to Mass Spectrometry*

    PubMed Central

    Rey, Martial; Man, Petr; Clémençon, Benjamin; Trézéguet, Véronique; Brandolin, Gérard; Forest, Eric; Pelosi, Ludovic

    2010-01-01

    The mitochondrial adenine nucleotide carrier (Ancp) catalyzes the transport of ADP and ATP across the mitochondrial inner membrane, thus playing an essential role in cellular energy metabolism. During the transport mechanism the carrier switches between two different conformations that can be blocked by two toxins: carboxyatractyloside (CATR) and bongkrekic acid. Therefore, our understanding of the nucleotide transport mechanism can be improved by analyzing structural differences of the individual inhibited states. We have solved the three-dimensional structure of bovine carrier isoform 1 (bAnc1p) in a complex with CATR, but the structure of the carrier-bongkrekic acid complex, and thus, the detailed mechanism of transport remains unknown. Improvements in sample processing in the hydrogen/deuterium exchange technique coupled to mass spectrometry (HDX-MS) have allowed us to gain novel insights into the conformational changes undergone by bAnc1p. This paper describes the first study of bAnc1p using HDX-MS. Results obtained with the CATR-bAnc1p complex were fully in agreement with published results, thus, validating our approach. On the other hand, the HDX kinetics of the two complexes displays marked differences. The bongkrekic acid-bAnc1p complex exhibits greater accessibility to the solvent on the matrix side, whereas the CATR-bAnc1p complex is more accessible on the intermembrane side. These results are discussed with respect to the structural and biochemical data available on Ancp. PMID:20805227

  5. Conformational dynamics of the bovine mitochondrial ADP/ATP carrier isoform 1 revealed by hydrogen/deuterium exchange coupled to mass spectrometry.

    PubMed

    Rey, Martial; Man, Petr; Clémençon, Benjamin; Trézéguet, Véronique; Brandolin, Gérard; Forest, Eric; Pelosi, Ludovic

    2010-11-01

    The mitochondrial adenine nucleotide carrier (Ancp) catalyzes the transport of ADP and ATP across the mitochondrial inner membrane, thus playing an essential role in cellular energy metabolism. During the transport mechanism the carrier switches between two different conformations that can be blocked by two toxins: carboxyatractyloside (CATR) and bongkrekic acid. Therefore, our understanding of the nucleotide transport mechanism can be improved by analyzing structural differences of the individual inhibited states. We have solved the three-dimensional structure of bovine carrier isoform 1 (bAnc1p) in a complex with CATR, but the structure of the carrier-bongkrekic acid complex, and thus, the detailed mechanism of transport remains unknown. Improvements in sample processing in the hydrogen/deuterium exchange technique coupled to mass spectrometry (HDX-MS) have allowed us to gain novel insights into the conformational changes undergone by bAnc1p. This paper describes the first study of bAnc1p using HDX-MS. Results obtained with the CATR-bAnc1p complex were fully in agreement with published results, thus, validating our approach. On the other hand, the HDX kinetics of the two complexes displays marked differences. The bongkrekic acid-bAnc1p complex exhibits greater accessibility to the solvent on the matrix side, whereas the CATR-bAnc1p complex is more accessible on the intermembrane side. These results are discussed with respect to the structural and biochemical data available on Ancp. PMID:20805227

  6. Structure-dependent degradation of polar compounds in weathered oils observed by atmospheric pressure photo-ionization hydrogen/deuterium exchange ultrahigh resolution mass spectrometry.

    PubMed

    Islam, Ananna; Kim, Donghwi; Yim, Un Hyuk; Shim, Won Joon; Kim, Sunghwan

    2015-10-15

    The resin fractions of fresh mixtures of three oils spilled during the M/V Hebei Spirit oil spill, as well as weathered oils collected at weathering stages II and IV from the oil spill site were analyzed and compared by atmospheric pressure photo-ionization hydrogen/deuterium exchange mass spectrometry (HDX MS). The significantly decreased abundance of N(+) and [N-H+D](+) ions suggested that secondary and tertiary amine-containing compounds were preferentially degraded during the early stage of weathering. [N+H](+) and [N+D](+) ions previously attributed to pyridine-type compounds degraded more slowly than secondary and tertiary amine-containing compounds. The preferential degradation of nitrogen-containing compounds was confirmed by photo-degradation experiments using 15 standard compounds. In addition, significant increases of [S1O1+H](+) and [S1O1+D](+) ions with higher DBE values were observed from fresh oil mixtures as compared to stages II and IV samples, and that could be linked with the decrease of higher DBE compounds of the S1 class. This study presented convincing arguments and evidence demonstrating that secondary and tertiary amines were more vulnerable to photo-degradation than compounds containing pyridine, and hence, preferential degradation depending on chemical structures must be considered in the production of hazardous or toxic components. PMID:25913675

  7. Goddard high-resolution spectrograph observations of the local interstellar medium and the deuterium/hydrogen ratio along the line of sight toward Capella

    NASA Technical Reports Server (NTRS)

    Linsky, Jeffrey L.; Brown, Alexander; Gayley, Ken; Diplas, Athanassios; Savage, Blair D.; Ayres, Thomas R.; Landsman, Wayne; Shore, Steven N.; Heap, Sara R.

    1993-01-01

    HST Goddard High-Resolution Spectrograph observations of the 1216, 2600, and 2800 A spectral regions are analyzed for the spectroscopic binary system Capella, obtained at orbital phase 0.26 with 3.27-3.57 km/s resolution and high SNR. The column densities of H I, D I, Mg II, and Fe II for the local interstellar medium along this 12.5 pc line of sight, together with estimates of the temperature and turbulent velocity are inferred. It is inferred that the atomic deuterium/hydrogen ratio by number is 1.65(+0.07, -0.18) x 10 exp -5 for this line of sight. Galactic evolution calculations indicate that the primordial D/H ratio probably lies in the range of (1.5-3) x (D/H)LISM. If H0 = 80 km/s Mpc, as recent evidence suggests, then the baryonic density in units of the Einstein-de Sitter closure density is 0.023-0.031. Thus the universe is argued to expand forever, unless nonbaryonic matter greatly exceeds the amount of baryonic matter.

  8. Identification of Pharmacological Chaperones for Gaucher Disease and Characterization of Their Effects on ?-Glucocerebrosidase by Hydrogen/Deuterium Exchange Mass Spectrometry

    PubMed Central

    Tropak, Michael B.; Kornhaber, Gregory J.; Rigat, Brigitte A.; Maegawa, Gustavo H.; Buttner, Justin D.; Blanchard, Jan E.; Murphy, Cecilia; Tuske, Steven J.; Coales, Stephen J.; Hamuro, Yoshitomo; Brown, Eric D.

    2010-01-01

    Point mutations in ?-glucocerebrosidase (GCase) can result in a deficiency of both GCase activity and protein in lysosomes thereby causing Gaucher Disease (GD). Enzyme inhibitors such as isofagomine, acting as pharmacological chaperones (PCs), increase these levels by binding and stabilizing the native form of the enzyme in the endoplasmic reticulum (ER), and allow increased lysosomal transport of the enzyme. A high-throughput screen of the 50 000-compound Maybridge library identified two, non-carbohydrate-based inhibitory molecules, a 2,4-diamino-5-substituted quinazoline (IC50 5 ?M) and a 5-substituted pyridinyl-2-furamide (IC50 8 ?M). They raised the levels of functional GCase 1.5–2.5-fold in N370S or F213I GD fibroblasts. Immunofluorescence confirmed that treated GD fibroblasts had decreased levels of GCase in their ER and increased levels in lysosomes. Changes in protein dynamics, monitored by hydrogen/deuterium-exchange mass spectrometry, identified a domain III active-site loop (residues 243–249) as being significantly stabilized upon binding of isofagomine or either of these two new compounds; this suggests a common mechanism for PC enhancement of intracellular transport. PMID:18972510

  9. Atomic hydrogen maser measurements with wall surfaces of carbon tetrafluoride

    NASA Technical Reports Server (NTRS)

    Vessot, R. F. C.; Mattison, E. M.; Imbier, E. A.; Zhai, Z. C.

    1984-01-01

    The principal objectives of the Smithsonian Astrophysical Observatory cold maser research programs are given. This work is aimed principally at understanding more about the interaction of hydrogen atoms with wall coatings of fluorinated ethylene propylene (Dupont Teflon FEP-120 co-polymer) and of carbon tetrafluoride (CE4). The principal measured quantity in these experiments is the wall shift of the maser's output frequency. The wall shift per atomic collision was calculated from the measured wall frequency shift. This assumes that the wall surface area is smooth on a molecular scale.

  10. Nanostructure modification to carbon nanowall surface employing hydrogen peroxide solution

    NASA Astrophysics Data System (ADS)

    Shimoeda, Hironao; Kondo, Hiroki; Ishikawa, Kenji; Hiramatsu, Mineo; Sekine, Makoto; Hori, Masaru

    2014-04-01

    Carbon nanowalls (CNWs), which are three-dimensional carbon nanomaterials consisting of stacks of graphene sheets vertically standing on substrates, possess a mazelike architecture containing high-density graphene edges and large-area plane surfaces. A selective morphological modification technique for the surfaces of CNWs after their growth has been developed employing hydrogen peroxide (H2O2) solution. It was found that oxidative radicals in H2O2 solution formed characteristic nanometer-scale asperities on the CNW surface without etching from the top edges. Photoelectron spectra indicate that hydroxyl adsorption and subsequent reactions at the edge and plane of graphene contribute to the selective morphological change on the CNW surface.

  11. Synthesis of carbon black/carbon nitride intercalation compound composite for efficient hydrogen production.

    PubMed

    Wu, Zhaochun; Gao, Honglin; Yan, Shicheng; Zou, Zhigang

    2014-08-21

    The photoactivity of g-C3N4 is greatly limited by its high recombination rate of photogenerated carriers. Coupling g-C3N4 with other materials has been demonstrated to be an effective way to facilitate the separation and transport of charge carriers. Herein we report a composite of conductive carbon black and carbon nitride intercalation compound synthesized through facile one-step molten salt method. The as-prepared carbon black/carbon nitride intercalation compound composite was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), UV-vis absorption spectrum and photoluminescence spectroscopy (PL). The carbon black nanoparticles, homogeneously dispersed on the surface of carbon nitride intercalation compound, efficiently enhanced separation and transport of photogenerated carriers, thus improving the visible-light photocatalytic activity. The composite of 0.5 wt% carbon black and carbon nitride intercalation compound exhibited a H2 production rate of 68.9 ?mol h(-1), which is about 3.2 times higher than hydrogen production on pristine carbon nitride intercalation compound. PMID:24975427

  12. Gas-driven hydrogen isotopes permeation through different carbon materials

    NASA Astrophysics Data System (ADS)

    Spitsyn, A. V.; Golubeva, A. V.; Mayer, M.; Skovoroda, A. A.

    2009-06-01

    Hydrogen gas driven permeation through the fine-grain graphites MPG-8 and R5710, and through CFC NB31 in two main directions has been investigated for sample thicknesses of 1-7 mm and pressures from 10 -2-10 Pa. The gas driven permeation occurs through the carbon-base materials by the hydrogen molecular gas flow through the internal porosity network rather than hydrogen atom diffusion through the graphite lattice. The permeabilities of MPG-8 and Nb31 are of the same order, while the permeability of R5710 is two orders of magnitude less. The specific bulk conductivity is about 5 × 10 15 molecules s -1 m -1 Pa -1 for MPG-8; 8 × 10 13 molecules s -1 m -1 Pa -1 for R5710; 1 × 10 16 molecules s -1 m -1 Pa -1 for Nb31 along ex-pitch ( x) fibers after taking into account the perforated surface layer and 0.8 × 10 16 molecules s -1 m -1 Pa -1 for Nb31 along needled ( z) fibers.

  13. Deposition of carbon, deuterium, and metals on the wall and limiters of the Tokamak Fusion Test Reactor

    SciTech Connect

    Wampler, W.R.; Doyle, B.L.; Lee, S.R.; Pontau, A.E.; Mills, B.E.; Causey, R.A.; Buchenauer, D.; Dylla, H.F.; Ulrickson, M.A.; LaMarche, P.H.

    1988-05-01

    Following a two-year operational period the Tokamak Fusion Test Reactor (TFTR) graphite fixed bumper limiter has been examined by a variety of methods. The areal density of metals was mapped in situ by beta backscattering. Several tiles were examined in detail by nuclear-reaction analysis, Rutherford backscattering, and proton-induced x-ray emission to measure areal densities of deuterium and impurities. Some areas of the limiter were found to be covered by deposited material several microns thick. Other areas where the incident plasma flux is higher were much cleaner. Long-term collection coupons were also examined to characterize deposition on the wall. From these results the total amount of deuterium on the limiter and wall in TFTR is estimated to be approx.1.3 x 10/sup 24/ atoms. The implications of this for wall-pumping effects and future tritium inventory are discussed.

  14. Determination of the gamma-ray asymmetry in the capture of polarized neutrons on hydrogen and deuterium.

    SciTech Connect

    Bowman, J. D. (J. David); Greene, G. L. (Geoff L.); Knudson, J. N. (James N.); Lamoreaux, Steve Keith; Mitchell, G. S. (Gregory S.); Morgan, G. L. (George Lake); Wilburn, W. S. (Wesley S.); Yuan, V. W. (Vincent W.); Penttila, S. I. (Seppo I.)

    2001-01-01

    The n+p{yields}d+{gamma} experiment measures the parity-violating directional gamma-ray asymmetry, A{gamma}, with uncertainties of 0.5x10{sup -8} when cold polarized neutrons are captured by para-hydrogen. This precision measurement will determine the long-range pion-nucleon weak coupling constant, H{sub {pi}}{sup 1}, with a precision of 10% of its predicted value, and thus will help to clarify our understanding of the weak interaction between nucleons. The n+p{yields}d+{gamma} experiment on the SNS beamline 14B is designed to take advantage of the high intensity of the source and its pulsed nature. The experiment requires a 30-Hz pulsed beam for optimal performance. In three months of run time the experiment will achieve a statistical uncertainty of 0.5x10{sup -8}.

  15. Deposition of carbon, deuterium, and metals on the wall and limiters of the Tokamak Fusion Test Reactor

    Microsoft Academic Search

    W. R. Wampler; B. L. Doyle; S. R. Lee; A. E. Pontau; B. E. Mills; R. A. Causey; D. Buchenauer; H. F. Dylla; M. A. Ulrickson; P. H. LaMarche

    1988-01-01

    Following a two-year operational period the Tokamak Fusion Test Reactor (TFTR) graphite fixed bumper limiter has been examined by a variety of methods. The areal density of metals was mapped in situ by beta backscattering. Several tiles were examined in detail by nuclear-reaction analysis, Rutherford backscattering, and proton-induced x-ray emission to measure areal densities of deuterium and impurities. Some areas

  16. Thermocatalytic process for CO.sub.2-free production of hydrogen and carbon from hydrocarbons

    DOEpatents

    Muradov, Nazim Z. (Melbourne, FL)

    2011-08-23

    A novel process and apparatus are disclosed for sustainable CO.sub.2-free production of hydrogen and carbon by thermocatalytic decomposition (dissociation, pyrolysis, cracking) of hydrocarbon fuels over carbon-based catalysts in the absence of air and/or water. The apparatus and thermocatalytic process improve the activity and stability of carbon catalysts during the thermocatalytic process and produce both high purity hydrogen (at least, 99.0 volume %) and carbon, from any hydrocarbon fuel, including sulfurous fuels. In a preferred embodiment, production of hydrogen and carbon is achieved by both internal and external activation of carbon catalysts. Internal activation of carbon catalyst is accomplished by recycling of hydrogen-depleted gas containing unsaturated and aromatic hydrocarbons back to the reactor. External activation of the catalyst can be achieved via surface gasification with hot combustion gases during catalyst heating. The process and apparatus can be conveniently integrated with any type of fuel cell to generate electricity.

  17. Deuterium trapping in deep traps of differently oriented pyrolytic graphite exposed to D 2 gas at 1473 K

    NASA Astrophysics Data System (ADS)

    Chernikov, V. N.; Wampler, W. R.; Zakharov, A. P.; Gorodetsky, A. E.

    1999-01-01

    Due to their importance for tritium inventories in future DT fueled fusion machines, experimental data on H isotope diffusion, absorption and retention in deep traps ( Eb ? 4.3 eV) of graphites exposed to hydrogen at elevated temperatures have been reviewed. Deuterium retention was studied in edge- and basal-oriented pyrolytic graphite (PG) and polycrystalline RG-Ti-91 damaged by irradiation with 200 keV carbon ions. Deuterium loading was done by soaking in D 2 gas at 1473 K, and the resulting D retention was measured by nuclear reaction analysis. The microstructure was studied by cross-sectional TEM, SEM and microprofilometry. The concentration of strong traps created by irradiation and estimated by the amount of accumulated deuterium was shown to saturate with the damage above ?1 dpa at about 1000 appm. In non-damaged and damaged graphites deuterium diffuses via porous grain boundaries and along basal planes within crystallites, while its migration through the graphite lattice along the c direction was found to be negligible. Radiation modifications of PG retard deuterium diffusion and decrease the rate of its chemical erosion by a factor of five. The amount of deuterium accumulated in strong traps in graphites is mainly influenced by their macro- and microstructure, while the degree of graphitization seems to be less important. Derivations are made of the susceptibility of damaged graphites, in particular, CFCs to the retention of hydrogen isotopes in deep traps.

  18. Hydrogen Adsorption on Activated Carbon an Carbon Nanotubes Using Volumetric Differential Pressure Technique

    SciTech Connect

    Sanip, S. M.; Saidin, M. A. R.; Aziz, M.; Ismail, A. F. [Membrane Research Unit, Faculty of Chemical and Natural Resources Engineering, Universiti Teknologi Malaysia, 81310, Skudai, Johor (Malaysia)

    2010-03-11

    A simple hydrogen adsorption measurement system utilizing the volumetric differential pressure technique has been designed, fabricated and calibrated. Hydrogen adsorption measurements have been carried out at temperatures 298 K and 77 K on activate carbon and carbon nanotubes with different surface areas. The adsorption data obtained will be helpful in understanding the adsorption property of the studied carbon materials using the fundamentals of adsorption theory. The principle of the system follows the Sievert-type method. The system measures a change in pressure between the reference cell, R1 and the sample cell S1, S2, S3 over a certain temperature range, R1, S1, S2, and S3 having known fixed volume. The sample temperatures will be monitored by thermocouple TC while the pressures in R1 an S1, S2, S3 will be measured using a digital pressure transducer. The maximum operating pressure of the pressure transducer is 20 bar and calibrated with an accuracy of +-0.01 bar. High purity hydrogen is being used in the system and the amount of samples for the study is between 1.0-2.0 grams. The system was calibrated using helium gas without any samples in S1, S2 an S3. This will provide a correction factor during the adsorption process providing an adsorption free reference point when using hydrogen gas resulting in a more accurate reading of the adsorption process by eliminating the errors caused by temperature expansion effects and other non-adsorption related phenomena. The ideal gas equation of state is applied to calculate the hydrogen adsorption capacity based on the differential pressure measurements. Activated carbon with a surface area of 644.87 m{sup 2}/g showed a larger amount of adsorption as compared to multiwalled nanotubes (commercial) with a surface area of 119.68 m{sup 2}/g. This study als indicated that there is a direct correlation between the amounts of hydrogen adsorbed an surface area of the carbon materials under the conditions studied and that the adsorption significant at 77 K.

  19. Micro Strip Gas Chambers Overcoated with Carbon, Hydrogenated Amorphous Silicon, and Glass Films

    E-print Network

    Micro Strip Gas Chambers Overcoated with Carbon, Hydrogenated Amorphous Silicon, and Glass Films M Abstract The performance of glass and sapphire substrate Micro Strip Gas Chambers with chromium and molybdenum elec­ trodes overcoated with carbon, hydrogenated amorphous silicon and glass layers are reported

  20. Development of Affordable, Low-Carbon Hydrogen Supplies at an Industrial Scale

    ERIC Educational Resources Information Center

    Roddy, Dermot J.

    2008-01-01

    An existing industrial hydrogen generation and distribution infrastructure is described, and a number of large-scale investment projects are outlined. All of these projects have the potential to generate significant volumes of low-cost, low-carbon hydrogen. The technologies concerned range from gasification of coal with carbon capture and storage…

  1. A STUDY TO EVALUATE CARBON MONOXIDE AND HYDROGEN SULFIDE CONTINUOUS EMISSION MONITORS AT AN OIL REFINERY

    EPA Science Inventory

    An eleven month field evaluation was done on five hydrogen sulfide and four carbon monoxide monitors located at an oil refinery. The hydrogen sulfide monitors sampled a fuel gas feed line and the carbon monoxide monitors sampled the emissions from a fluid cat cracker (FCC). Two o...

  2. Hydrogen content and bonding structure of diamond-like carbon films deposited by ion beam deposition

    Microsoft Academic Search

    Tanaka Koki; Okada Morihiro; Kohno Takumi; Yanokura Minoru; Aratani Michi

    1991-01-01

    Diamond-like carbon films were deposited from methane gas by ion beam deposition. The hydrogen content and bonding structure of the films were studied as a function of deposition conditions. The hydrogen concentration was measured by elastic recoil detection analysis with a 50 MeV Ar ion beam and the bonding structure determined by IR and Raman spectroscopy. The hydrogen content of

  3. The hydrogen concentration of diamondlike amorphous carbon films by elastic recoil detection analysis

    Microsoft Academic Search

    Xianguan Long; Xiufeng Peng; Fuqing He; Mantian Liu; Xigang Lin

    1992-01-01

    By using elastic recoil detection analysis, the hydrogen concentration of amorphous carbon films prepared by ion beam deposition was determined. The dependence of the hydrogen concentration on the deposition parameters (energy of ion beam, beam current density, and ratio of hydrogen to methane in gas mixture) was observed for these films. It seems clear that the diamond cubic structure in

  4. Production of carbon monoxide-free hydrogen and helium from a high-purity source

    DOEpatents

    Golden, Timothy Christopher (Allentown, PA); Farris, Thomas Stephen (Bethlehem, PA)

    2008-11-18

    The invention provides vacuum swing adsorption processes that produce an essentially carbon monoxide-free hydrogen or helium gas stream from, respectively, a high-purity (e.g., pipeline grade) hydrogen or helium gas stream using one or two adsorber beds. By using physical adsorbents with high heats of nitrogen adsorption, intermediate heats of carbon monoxide adsorption, and low heats of hydrogen and helium adsorption, and by using vacuum purging and high feed stream pressures (e.g., pressures of as high as around 1,000 bar), pipeline grade hydrogen or helium can purified to produce essentially carbon monoxide -free hydrogen and helium, or carbon monoxide, nitrogen, and methane-free hydrogen and helium.

  5. Carbon, Hydrogen, and Silicon-containing Solid Lubricants

    NASA Astrophysics Data System (ADS)

    Harrison, Judith

    2005-03-01

    The development of micro-sized devices has prompted the need for protection of the surfaces of these devices. Amorphous carbon films (a-C and a-CH), doped carbon films, and self- assembled monolayers (SAMs) are all possible candidates for the passivation and lubrication of these devices. The fundamental problem associated with controlling friction and wear is a lack of understanding of the underlying atomic-scale chemical and physical processes that govern them. Extensive molecular dynamics (MD) simulations have been done that have examined the compression and friction of model hydrocarbon SAMs, amorphous carbon- and silicon-containing films both with and without hydrogen. We have examined the contact forces present at the interface between a tip and pure, or mixed-length, SAMs during sliding. Compression and shear-induced polymerization have also been modeled in unsaturated hydrocarbon films. In addition, we have also done simulations that analyze the mechanical and tribological properties of a-C, a-CH, a-C-Si, and a-C-Si-H films. Some of our recent results will be discussed.

  6. Hydrogen induced redox mechanism in amorphous carbon resistive random access memory

    PubMed Central

    2014-01-01

    We investigated the bipolar resistive switching characteristics of the resistive random access memory (RRAM) device with amorphous carbon layer. Applying a forming voltage, the amorphous carbon layer was carbonized to form a conjugation double bond conductive filament. We proposed a hydrogen redox model to clarify the resistive switch mechanism of high/low resistance states (HRS/LRS) in carbon RRAM. The electrical conduction mechanism of LRS is attributed to conductive sp2 carbon filament with conjugation double bonds by dehydrogenation, while the electrical conduction of HRS resulted from the formation of insulating sp3-type carbon filament through hydrogenation process. PMID:24475979

  7. Hydrogen retention in graphite and carbon materials under a fusion reactor environment

    NASA Astrophysics Data System (ADS)

    Atsumi, H.

    2003-03-01

    Bulk hydrogen retention and hydrogen diffusion in graphite and carbon materials have been studied to estimate hydrogen recycling and tritium inventory under a fusion reactor environment. Two kinds of hydrogen trapping sites may exist. The first will be one of lined carbon dangling bonds located at the edge surface of a crystallite with an adsorption enthalpy of 2.6 eV, the second will be a solitary carbon dangling bond, such as an interstitial cluster loop edge, with an enthalpy of 4.4 eV. The correlation between hydrogen retention and the microstructure should refer to the edge surface area of a crystallite for an unirradiated sample and to lattice spacing along the c axis for an irradiated sample. The diffusion process is the rate-determining step for hydrogen absorption into graphite, and detrapping dominates the hydrogen desorption process due to the high trapping energy.

  8. Understanding the conformational impact of chemical modifications on monoclonal antibodies with diverse sequence variation using hydrogen/deuterium exchange mass spectrometry and structural modeling.

    PubMed

    Zhang, Aming; Hu, Ping; MacGregor, Paul; Xue, Yu; Fan, Haihong; Suchecki, Peter; Olszewski, Leonard; Liu, Aston

    2014-04-01

    Chemical modifications can potentially induce conformational changes near the modification site and thereby impact the safety and efficacy of protein therapeutics. Hydrogen/deuterium exchange mass spectrometry (HDX-MS) has emerged as a powerful analytical technique with high spatial resolution and sensitivity in detecting such local conformational changes. In this study, we utilized HDX-MS combined with structural modeling to examine the conformational impact on monoclonal antibodies (mAbs) caused by common chemical modifications including methionine (Met) oxidation, aspartic acid (Asp) isomerization, and asparagine (Asn) deamidation. Four mAbs with diverse sequences and glycosylation states were selected. The data suggested that the impact of Met oxidation was highly dependent on its location and glycosylation state. For mAbs with normal glycosylation in the Fc region, oxidation of the two conserved Met252 and Met428 (Kabat numbering) disrupted the interface interactions between the CH2 and CH3 domains, thus leading to a significant decrease in CH2 domain thermal stability as well as a slight increase in aggregation propensity. In contrast, Met oxidation in the variable region and CH3 domain had no detectable impact on mAb conformation. For aglycosylated mAb, Met oxidation could cause a more global conformational change to the whole CH2 domain, coincident with the larger decrease in thermal stability and significant increase in aggregation rate. Unlike Met oxidation, Asn deamidation and Asp isomerization mostly had very limited effects on mAb conformation, with the exception of succiminide intermediate formation which induced a measurable local conformational change to be more solvent protected. Structural modeling suggested that the succinimide intermediate was stabilized by adjacent aromatic amino acids through ring-ring stacking interactions. PMID:24597564

  9. The combination of hydrogen/deuterium exchange or chemical cross-linking techniques with mass spectrometry: mapping of human 14-3-3? homodimer interface.

    PubMed

    Haladová, Kate?ina; Mrázek, Hynek; Je?men, Tomáš; Halada, Petr; Man, Petr; Novák, Petr; Chmelík, Josef; Obšil, Tomáš; Šulc, Miroslav

    2012-07-01

    Hydrogen/deuterium (H/D) exchange or chemical cross-linking by soluble carbodiimide (EDC) was employed in combination with high-resolution mass spectrometry (MS) to extend our knowledge about contact surface regions involved in the well-characterized model of interaction between two molecules of human 14-3-3? regulatory protein. The H/D exchange experiment provided low resolution mapping of interaction in the homodimeric 14-3-3? complex. A lower level of deuteration, suggesting structural protection, of two sequential segments has been demonstrated for dimeric 14-3-3? wild type relative to the monomeric mutant 14-3-3? S58D. The N-terminal sequence (the first 27 residues) from one subunit interacts with region ?C'and ?D'-helices (residues 45-98) of the other molecule across the dimer interface. To identify interacting amino acid residues within the studied complex, a chemical cross-linking reaction was carried out to produce the covalent homodimer, which was detected by SDS-PAGE. The MS analysis (following tryptic in-gel digestion) employing both high resolution and tandem mass spectrometry revealed cross-linked amino acid residues. Two alternative salt bridges between Glu81 and either Lys9 or the N-terminal amino group have been found to participate in transient interactions of the 14-3-3? isotype homodimerization. The data obtained, which have never previously been reported, were used to modify the published 14-3-3 crystal structure using molecular modeling. Based on our findings, utilization of this combination of experimental approaches, which preserve protein native structures, is suitable for mapping the contact between two proteins and also allows for the description of transient interactions or of regions with flexible structure in the studied protein complexes. PMID:22580067

  10. Unfolding and aggregation of a glycosylated monoclonal antibody on a cation exchange column. Part II. Protein structure effects by hydrogen deuterium exchange mass spectrometry.

    PubMed

    Guo, Jing; Carta, Giorgio

    2014-08-22

    Hydrogen-deuterium exchange mass spectrometry (HX-MS) with proteolytic fragmentation is used to determine patterns of unfolding, as measured by increased solvent exposure, with peptide-level resolution for a glycosylated monoclonal antibody both when eluted from a tentacle-type cation exchange column (Fractogel EMD SO3-) and while bound to the resin. Two peaks are obtained when the bound protein is eluted with either a NaCl gradient or with two NaCl steps at increasing concentration. The first, early eluting peak contains only monomeric species whose structure is consistent with the native monomer. The second, late eluting peak contains a mixture of monomeric and aggregated species. The monomeric species in this mixture is also found to have a structure consistent with that of the native mAb, showing no evidence of increased solvent exposure. The aggregated species show instead significant unfolding in areas of the protein structure contained within the Fc region. The same peptides that exhibit the greatest level of solvent exposure in the aggregated species are also found in the fraction of protein that elutes from the resin only at high salt concentration, indicating that the aggregates are formed when the strongly-bound unfolded intermediate is desorbed at high salt. There is no evidence that the unfolded intermediate, formed while the protein is bound on the resin, is present in any of the eluted fractions indicating that, upon desorption from the resin, the intermediate either quickly refolds or forms aggregates which end-up co-eluting with the refolded protein at high salt concentrations. PMID:25011681

  11. Interdependence of coenzyme-induced conformational work and binding potential in yeast alcohol and porcine heart lactate dehydrogenases: a hydrogen-deuterium exchange study

    SciTech Connect

    De Weck, Z.; Pande, J.; Kaegi, J.H.R.

    1987-07-28

    Binding of NAD coenzymes to yeast alcohol dehydrogenase (YADH) and porcine heart lactate dehydrogenase (PHLDH) was studied by hydrogen-deuterium exchange with the infrared technique. Conformational changes in the enzymes specific to the coenzymes and their fragments were observed, and the pH dependence of the exchange reaction shows that it conforms to the EX-2 scheme. In both YADH and PHLDH the magnitude of the conformational change as measured by exchange retardation is considerably larger for the NAD/sup +/ than for NADH. Studies with coenzyme fragments like ADP-ribose, ADP, and AMP also highlight the lack of rigorous correlation between structural features such as charge and size and their influence on exchange behavior. Ternary complexes such as YADH-NAD/sup +/-pyrazole, PHLDH-NAD/sup +/-oxalate, and PHLDH-NADH-oxamate, which mimic the transition state, have a significantly more pronounced effect on exchange rates than the corresponding binary complexes. The outstanding feature of this study is the demonstration that in the binary enzyme-coenzyme complexes the more loosely bound NAD/sup +/ is more effective in retarding exchange than the more firmly bound NADH. These differences are attributed to the unequal structural constraints exerted by the two coenzymes upon the enzymes, which translate to unequal expenditure of transconformational work in the formation of the two complexes. The opposing variation in the free energy of binding and the transconformational work expended can be viewed as an unequal partitioning of the net free energy gain resulting from the protein-ligand interaction into a binding term and that required for conformational change.

  12. Epitope mapping of inhibitory antibodies targeting the C2 domain of coagulation factor VIII by hydrogen-deuterium exchange mass spectrometry

    PubMed Central

    Sevy, Alexander M.; Healey, John F.; Deng, Wei; Spiegel, P. Clint; Meeks, Shannon L.; Li, Renhao

    2014-01-01

    Summary Background The development of anti-factor VIII (fVIII) antibodies (inhibitors) is a significant complication in the management of patients with hemophilia A, leading to significant increases in morbidity and treatment cost. Using a panel of anti-fVIII monoclonal antibodies (MAbs) to different epitopes on fVIII, we recently have shown that epitope specificity, inhibitor kinetics, and time to maximum inhibition are more important than inhibitor titer in predicting response to fVIII and the combination of fVIII and recombinant factor VIIa. In particular, a subset of high-titer inhibitors responded to high dose fVIII, which would not be predicted based on their inhibitor titer alone. Thus the ability to quickly map the epitope spectrum of patient plasma using a clinically feasible assay may fundamentally change how clinicians approach the treatment of high-titer inhibitor patients. Objectives To map the epitopes of anti-fVIII MAbs, of which 3 are classical inhibitors and one non-classical, using hydrogen-deuterium exchange coupled with liquid chromatography-mass spectrometry (HDX-MS). Methods Binding epitopes of 4 MAbs targeting fVIII C2 domain were mapped using HDX-MS. Results The epitopes determined by HDX-MS are consistent with those obtained earlier through structural characterization and antibody competition assays. In addition classical and non-classical inhibitor epitopes could be distinguished using a limited subset of C2-derived peptic fragments. Conclusion Our results demonstrate the effectiveness and robustness of the HDX-MS method for epitope mapping and suggest a potential role of rapid mapping of fVIII inhibitor epitopes in facilitating individualized treatment of inhibitor patients. PMID:24152306

  13. Suppression of carbon erosion by hydrogen shielding during high-flux hydrogen bombardment E. Salonen, K. Nordlund, J. Tarus, T. Ahlgren, and J. Keinonen

    E-print Network

    Nordlund, Kai

    Suppression of carbon erosion by hydrogen shielding during high-flux hydrogen bombardment E Garching bei Mu¨nchen, Germany Received 3 August 1999 The erosion of carbon by intensive hydrogen cannot be explained by standard sputtering or erosion mod- els, yet understanding it is central

  14. Hydrogen storage system based on novel carbon materials and heat pipe heat exchanger

    Microsoft Academic Search

    L. L. Vasiliev; L. E. Kanonchik; A. G. Kulakov; V. A. Babenko

    2007-01-01

    Adsorbed hydrogen is being considered as a potential energy carrier for vehicular applications to replace compressed gas due to its high energy density capability. A new design of hydrogen storage vessel using novel carbon sorbents and heat pipes thermal control is the subject of research program oriented on 5–10 kg of hydrogen be stored on-board. Porous structure and hydrogen-sorption capacities

  15. High electric field deuterium ion sources for neutron generators

    NASA Astrophysics Data System (ADS)

    Reichenbach, Birk

    Active interrogation systems for highly enriched uranium require improved fieldable neutron sources. The target technology for deuterium-tritium neutron generators is well understood and the most significant improvement can be achieved by improving the deuterium ion source through increased output and, in some cases, lifetime of the ion source. We are developing a new approach to a deuterium ion sources based upon the field desorption/evaporation of deuterium from the surfaces of metal tips. Electrostatic field desorption (EFD) desorbs previously adsorbed deuterium as ions under the influence of high electric fields (several V/A), without removing tip material. Single etched wire tip experiments have been performed and have shown that this is difficult but can be achieved with molybdenum and tungsten tips. Electrostatic field evaporation (EFE) evaporates ultra thin deuterated titanium films as ions. It has been shown that several 10s of atomic layers can be removed within a few nanoseconds from etched tungsten tips. In the course of these studies titanium deposition and deuteration methods were studied and new detection methods developed. Space charge effects resulting from the large ion currents were identified to be the most likely cause of some unusual ion emission characteristics. In addition, on W < 110 > oriented substrates a surprising body-centered cubic crystal structure of the titanium film was found and studied. The ion currents required for neutron generator applications can be achieved by microfabrication of metal tip arrays. Field desorption studies of microfabricated field emitter tip arrays have been conducted for the first time. Maximum fields of 3 V/A have been applied to the array tip surfaces to date, although fields of ˜ 2 V/A to ˜ 2.5 V/A are more typical. Desorption of atomic deuterium ions has been observed at fields of roughly 2 V/A at room temperature. The desorption of common surface adsorbates, such as hydrogen, carbon, water, and carbon monoxide is observed at fields exceeding ˜1 V/A. In vacuo heating of the arrays to temperatures of the order of 800°C can be effective in removing many of the surface contaminants observed. For both the field desorption and the field evaporation approaches further improvements to array design and fabrication are required if arrays are to provide sufficient deuterium ion currents to produce 109 to 1010 n/cm2 of tip array area for the detection systems.

  16. Spreading of PFPE lubricants on carbon surfaces: effect of hydrogen and nitrogen content

    Microsoft Academic Search

    Xiaoding Ma; Jing Gui; Kevin J. Grannen; Laura A. Smoliar; Bruno Marchon; Myung S. Jhon; Charles L. Bauer

    1999-01-01

    The spreading of OH-terminated perfluoropolyalkylether (PFPE), Zdol, on amorphous carbon surfaces was studied as a function\\u000a of hydrogen or nitrogen content in the carbon film, using scanning micro-ellipsometry. A layered structure of the thickness\\u000a profiles was observed, which remained qualitatively the same for all carbon types. The sharpness of the second layer was gradually\\u000a eroded as either hydrogen or nitrogen

  17. Deuterium enrichment by selective photo-induced dissociation of an organic carbonyl compound

    DOEpatents

    Marling, John B. (Livermore, CA)

    1981-01-01

    A method for producing a deuterium enriched material by photoinduced dissociation which uses as the working material a gas phase photolytically dissociable organic carbonyl compound containing at least one hydrogen atom bonded to an atom which is adjacent to a carbonyl group and consisting of molecules wherein said hydrogen atom is present as deuterium and molecules wherein said hydrogen atom is present as another isotope of hydrogen. The organic carbonyl compound is subjected to intense infrared radiation at a preselected wavelength to selectively excite and thereby induce dissociation of the deuterium containing species to yield a deuterium enriched stable molecular product. Undissociated carbonyl compound, depleted in deuterium, is preferably redeuterated for reuse.

  18. Dynamic Monte-Carlo modeling of hydrogen isotope reactive diffusive transport in porous graphite

    NASA Astrophysics Data System (ADS)

    Schneider, R.; Rai, A.; Mutzke, A.; Warrier, M.; Salonen, E.; Nordlund, K.

    2007-08-01

    An equal mixture of deuterium and tritium will be the fuel used in a fusion reactor. It is important to study the recycling and mixing of these hydrogen isotopes in graphite from several points of view: (i) impact on the ratio of deuterium to tritium in a reactor, (ii) continued use of graphite as a first wall and divertor material, and (iii) reaction with carbon atoms and the transport of hydrocarbons will provide insight into chemical erosion. Dynamic Monte-Carlo techniques are used to study the reactive-diffusive transport of hydrogen isotopes and interstitial carbon atoms in a 3-D porous graphite structure irradiated with hydrogen and deuterium and is compared with published experimental results for hydrogen re-emission and isotope exchange.

  19. Single Pd atoms in activated carbon fibers and their contribution to hydrogen storage 5

    E-print Network

    Pennycook, Steve

    Single Pd atoms in activated carbon fibers and their contribution to hydrogen storage 5 Cristian I carbon fibers (Pd-ACF) were synthesized by melt-spinning, carbonization and activation of an isotropic 2010 Accepted 14 May 2011 Available online 20 May 2011 A B S T R A C T Palladium-modified activated

  20. Kinetics of the Homogeneous Catalytic Hydrogenation of Olefins in Supercritical Carbon Dioxide Using a Fluoroacrylate Copolymer

    E-print Network

    Abdou, Hanan E.

    Kinetics of the Homogeneous Catalytic Hydrogenation of Olefins in Supercritical Carbon Dioxide a fluoroacrylate copolymer grafted rhodium catalyst in supercritical carbon dioxide (scCO2) are reported field of chemical reaction engineering.3-8 Specifically, supercritical carbon dioxide (scCO2

  1. PERGAMON Carbon 38 (2000) 17571765 High temperature hydrogen sulfide adsorption on activated

    E-print Network

    Cal, Mark P.

    2000-01-01

    temperature was examined as a2 function of carbon surface chemistry (oxidation, thermal desorption, and metalPERGAMON Carbon 38 (2000) 1757­1765 High temperature hydrogen sulfide adsorption on activated gas stream2 at a temperature of 5508C. The ability of activated carbon to remove H S at elevated

  2. PERGAMON Carbon 38 (2000) 17671774 High temperature hydrogen sulfide adsorption on activated

    E-print Network

    Cal, Mark P.

    2000-01-01

    PERGAMON Carbon 38 (2000) 1767­1774 High temperature hydrogen sulfide adsorption on activated carbon II. Effects of gas temperature, gas pressure and sorbent regeneration 1 2 3 *M.P. Cal , B of activated carbon sorbents were evaluated for removal of H S at high temperatures (400­6008C) in an2

  3. Sputtering and codeposition of silicon carbide with deuterium

    NASA Astrophysics Data System (ADS)

    Causey, Rion A.

    2003-03-01

    Due to its excellent thermal properties, silicon carbide is being considered as a possible plasma-facing material for fusion devices. If used as a plasma-facing material, the energetic hydrogen isotope ions and charge-exchanged neutrals escaping from the plasma will sputter the silicon carbide. To assess the tritium inventory problems that will be generated by the use of this material, it is necessary that we know the codeposition properties of the redeposited silicon carbide. To determine the codeposition properties, the deuterium plasma experiment at Sandia National Laboratories in Livermore, California has been used to directly compare the deuterium sputtering and codeposition of silicon carbide with that of graphite. A Penning discharge at a flux of 6×10 19 D/m 2 and an energy of ?300 eV was used to sputter silicon and carbon from a pair of 0.05 m diameter silicon carbide disks. The removal rate of deuterium gas from the fixed volume of the system isolated from all other sources and sinks was used to measure the codeposition probability (probability that a hydrogen isotope atom will be removed through codeposition per ion striking the sample surface). A small catcher plate used to capture a fraction of the codeposited film was analyzed using Auger spectroscopy. This analysis showed the film to begin with a high carbon to silicon ratio due to preferential sputtering of the carbon. As the film became thicker, the ratio of the depositing material changed over to the (1:1) value that must eventually be attained.

  4. Structure and hydrogen adsorption properties in low density nanoporous carbons from simulations

    SciTech Connect

    Peng, L. [University of Tennessee, Knoxville (UTK); Morris, James R [ORNL

    2012-01-01

    We systematically model the hydrogen adsorption in nanoporous carbons over a wide range of carbon bulk densities (0.6 - 2.4 g/cm3) by using tight binding molecular dynamics simulations for the carbon structures and thermodynamics calculations of the hydrogen adsorption. The resulting structures are in good agreement with the experimental data of ultra-microporous carbon (UMC), a wood-based activated carbon, as indicated by comparisons of the microstructure at atomic level, pair distribution function, and pore size distribution. The hydrogen adsorption calculations in carbon structures demonstrate both a promising hydrogen storage capacity (excess uptake of 1.33 wt% at 298K and 5 MPa, for carbon structures at the lower range of densities) and a reasonable heat of adsorption (12-22 kJ/mol). This work demonstrates that increasing the heat of adsorption does not necessarily increase the hydrogen uptake. In fact, the available adsorption volume is as important as the isosteric heat of adsorption for hydrogen storage in nanoporous carbons.

  5. Study of depth profile of hydrogen in hydrogenated diamond like carbon thin film using ion beam analysis techniques

    NASA Astrophysics Data System (ADS)

    Datta, J.; Biswas, H. S.; Rao, P.; Reddy, G. L. N.; Kumar, S.; Ray, N. R.; Chowdhury, D. P.; Reddy, A. V. R.

    2014-06-01

    The Hydrogenated Diamond Like Carbon (HDLC) thin films are deposited on Silicon substrate at room temperature using asymmetric capacitively coupled RF plasma with varying flow rates of methane. These films are undergone annealing at high vacuum (˜10-7 torr) and high temperature (750 and 1050 °C) furnace. The as-prepared and annealed HDLC films have been depth profiled for hydrogen using the resonance at 6.44 MeV in 1H(19F,??)16O nuclear reaction. The as prepared films exhibit non-uniform depth distribution of hydrogen: it decreases with depth. Annealing in vacuum brings about is a significant desorption of hydrogen from the films. Loss of hydrogen, albeit in much lower proportions, is also induced by the bombarding beam. The films also experience a mild loss of carbon, as shown by proton backscattering spectrometry, during high vacuum annealing. The depth profiles of hydrogen in the annealed films are indicative of the prevalence of graphitic carbon near film-substrate interface.

  6. Fast-quench reactor for hydrogen and elemental carbon production from natural gas and other hydrocarbons

    DOEpatents

    Detering, Brent A.; Kong, Peter C.

    2006-08-29

    A fast-quench reactor for production of diatomic hydrogen and unsaturated carbons is provided. During the fast quench in the downstream diverging section of the nozzle, such as in a free expansion chamber, the unsaturated hydrocarbons are further decomposed by reheating the reactor gases. More diatomic hydrogen is produced, along with elemental carbon. Other gas may be added at different stages in the process to form a desired end product and prevent back reactions. The product is a substantially clean-burning hydrogen fuel that leaves no greenhouse gas emissions, and elemental carbon that may be used in powder form as a commodity for several processes.

  7. Passive colorimetric dosimeter tubes for ammonia, carbon monoxide, carbon dioxide, hydrogen sulfide, nitrogen dioxide, and sulfur dioxide

    Microsoft Academic Search

    E. S. McKee; I. M. Pritts

    1981-01-01

    Colorimetric, stain length, personal dosimeters operating by gas diffusion have been developed to determine worker exposure for up to an 8-h period for several inorganic airborne contaminants in the range of their threshold limit values. Length of stain, colorimetric dosimeters have been made for the detection of ammonia (NHâ), carbon monoxide (CO), carbon dioxide (COâ), hydrogen sulfide (HâS), nitrogen dioxide

  8. Hydrogen storage in different carbon materials: Influence of the porosity development by chemical activation

    NASA Astrophysics Data System (ADS)

    Jiménez, Vicente; Ramírez-Lucas, Ana; Sánchez, Paula; Valverde, José Luís; Romero, Amaya

    2012-01-01

    The hydrogen adsorption capacity of different types of carbon nanofibers (platelet, fishbone and ribbon) and amorphous carbon have been measured as a function of pressure and temperature. The results showed that the more graphitic carbon materials adsorbed less hydrogen than more amorphous materials. After a chemical activation process, the hydrogen storage capacities of the carbon materials increased markedly in comparison with the non-activated ones. BET surface area of amorphous carbon increased by a factor of 3.5 and the ultramicropore volume doubled, thus increasing the hydrogen adsorption by a factor of 2. However, BET surface area in platelet CNFs increased by a factor of 3 and the ultramicropore volume by a factor of 6, thus increasing the hydrogen storage by a factor of 4.5. The dependency of hydrogen storage capacity of carbon materials on the BET surface area was evaluated using both a condensation model and experimental results. Comparison of data suggests that the hydrogen adsorption capacity clearly depends on the pore structure and so, on the accessibility to the internal surface.

  9. Quantum fluctuations increase the self-diffusive motion of para-hydrogen in narrow carbon nanotubes.

    PubMed

    Kowalczyk, Piotr; Gauden, Piotr A; Terzyk, Artur P; Furmaniak, Sylwester

    2011-05-28

    Quantum fluctuations significantly increase the self-diffusive motion of para-hydrogen adsorbed in narrow carbon nanotubes at 30 K comparing to its classical counterpart. Rigorous Feynman's path integral calculations reveal that self-diffusive motion of para-hydrogen in a narrow (6,6) carbon nanotube at 30 K and pore densities below ?29 mmol cm(-3) is one order of magnitude faster than the classical counterpart. We find that the zero-point energy and tunneling significantly smoothed out the free energy landscape of para-hydrogen molecules adsorbed in a narrow (6,6) carbon nanotube. This promotes a delocalization of the confined para-hydrogen at 30 K (i.e., population of unclassical paths due to quantum effects). Contrary the self-diffusive motion of classical para-hydrogen molecules in a narrow (6,6) carbon nanotube at 30 K is very slow. This is because classical para-hydrogen molecules undergo highly correlated movement when their collision diameter approached the carbon nanotube size (i.e., anomalous diffusion in quasi-one dimensional pores). On the basis of current results we predict that narrow single-walled carbon nanotubes are promising nanoporous molecular sieves being able to separate para-hydrogen molecules from mixtures of classical particles at cryogenic temperatures. PMID:21503294

  10. Novel nanoporous carbon membranes for recovery of hydrogen from refinery waste gas

    SciTech Connect

    Rao, M.B.; Sircar, S. [Air Products and Chemicals, Inc., Allentown, PA (United States)

    1996-12-31

    Petroleum refineries are among the largest users of hydrogen in the chemical industry. Hydrogen is used in hydrogenation, desulfurization and denitrogenation processes and a large source of hydrogen in refining operations is the production of aromatic compounds which are used as octane enhancers in gasoline. Environmental regulations are requiring refiners to reduce the amount of aromatic compounds in transportation fuel and, thus, the total amount of hydrogen produced in dehydrogenation processes is being reduced. In addition, refineries are being forced to use crudes which are higher in sulfur which further increases the total H{sub 2} needs. This requires refiners to make or buy hydrogen by conventional methods such as Steam-Methane Reforming or to recover hydrogen from their processes. The purpose of this paper is to describe the preparation and performance of a new carbon-based gas separation membrane and its application in two new processes for hydrogen recovery from refinery waste streams.

  11. Minimisation of carbon monoxide in a hydrogen stream for fuel cell application

    Microsoft Academic Search

    D. L. Trimm

    2005-01-01

    Means of minimising carbon monoxide in a hydrogen stream for fuel cell operation are reviewed. Reduction of carbon monoxide to an acceptable level of 10–50ppm involves high temperature and low temperature water gas shift, followed by selective oxidation of residual carbon monoxide. Methanation of very small amounts of carbon monoxide may be an alternative final step.A new range of promoted

  12. Deep inelastic structure functions from electron scattering on hydrogen, deuterium, and iron at 0. 6 GeV sup 2 le Q sup 2 le 30. 0 GeV sup 2

    SciTech Connect

    Whitlow, L.W.

    1990-03-01

    We report the final results from experiment E140, a recent deep inelastic electron-deuterium and electron-iron scattering experiment at SLAC. In addition, we present the results of a combined global analysis of all SLAC deep inelastic electron-hydrogen and electron-deuterium cross section measurements between 1970 and 1983. Data from seven earlier experiments are re-radiatively corrected and normalized to experiment E140. We report extractions of R(x,Q{sup 2}) and F{sub 2}(x,Q{sup 2}) for hydrogen and deuterium over the entire SLAC kinematic range: .06{le} x {le}.90 and 0.6{le} Q{sup 2} {le}30.0 (GeV{sup 2}). We fine that R{sup p} = R{sup d}, as expected by QCD. Extracted values of R(x,Q{sup 2}) are significantly larger than predictions based on QCD and on QCD with the inclusion of kinematic target mass terms. This difference indicates that dynamical higher twist effects may be important in the SLAC kinematic range. A best fit empirical model of R(x,Q{sup 2}) is used to extract F{sub 2} from each cross section measurement. These F{sub 2} extractions are compared with F{sub 2} data from EMC and BCDMS. Agreement is observed with EMC when the EMC data are multiplied by 1.07. Agreement is observed with BCDMS over a limited range in x. The ratios of F{sub 2}{sup d}/F{sub 2}{sup p} are examined for Q{sup 2} dependence. We observe a significant negative slope for x {le} .6, and a significant positive slope above x > .7, in excellent agreement with predictions based on QCD with the inclusion of kinematic target mass terms. 111 refs., 40 figs., 34 tabs.

  13. SEASONAL VARIATIONS OF STABLE HYDROGEN AND CARBON ISOTOPE RATIOS OF METHANE IN SUBTROPICAL FRESHWATER SEDIMENTS

    EPA Science Inventory

    Stable hydrogen (D) and carbon (13C) isotope ratios of sedimentary methane from five subtropical Florida freshwater sites exhibited smaller, less distinct seasonal variations than previously observed in temperate sediments, apparently due to the smaller range of temperatures forc...

  14. The solubility of elemental sulfur in methane, carbon dioxide and hydrogen sulfide gas

    E-print Network

    Wieland, Denton R.

    1958-01-01

    THE SOLUBILITY OF ELEMENTAL SULFUR IN METHANE, CARBON DIOXIDE AND HYDROGEN SULFIDE GAS By Denton R. Wieland A Dissertation Submitted to the Graduate School of The Agricultural and Mechanical College of Texas in partial fulfillment... of the requirements for the degree of DOCTOR OF PHILOSOPHY January 1958 Major Subject: Petroleum Engineering THE SOLUBILITY OF ELEMENTAL SULFUR IN METHANE, CARBON DIOXIDE AND HYDROGEN SULFIDE GAS A Dissertation By DENTON R. WlELAND Library A * "COLLEGE...

  15. Structure and mechanical properties of hydrogenated carbon films prepared by magnetron sputtering

    Microsoft Academic Search

    B. Marchon; P. N. Vo; M. R. Khan; J. W. II Ager

    1991-01-01

    This paper reports on hydrogenated thin carbon films which have been prepared by DC-magnetron sputtering in an hydrogen-containing Argon atmosphere. A monotonic decrease in friction buildup as well as an increase in abrasion resistance is observed for increasing hydrogen proportion in Argon, from 0 to 5%. At the same time, Raman data shows higher sp³ character and an increase in

  16. Electrochemical Removal of Carbon Monoxide in Reformate Hydrogen for Fueling Proton Exchange Membrane

    E-print Network

    Weidner, John W.

    Electrochemical Removal of Carbon Monoxide in Reformate Hydrogen for Fueling Proton Exchange Membrane Fuel Cells Sivagaminathan Balasubramanian, Charles E. Holland,* and John W. Weidner*,z Center in reformate hydrogen. In this design, the potential and gas flow are switched between the two filter cells so

  17. PHYSIOLOGICAL ECOLOGY -ORIGINAL PAPER Carbon and hydrogen isotope fractionation under continuous

    E-print Network

    for plants under continuous light conditions during a 24-h transpiration cycle. Apparent hydrogen isotope light: implications for paleoenvironmental interpretations of the High Arctic during Paleogene warming intensity continuous light, e.g., in the High Arctic summer, on plant carbon and hydrogen isotope

  18. Hydrogen embrittlement in 0.31% carbon steel used for petrochemical applications

    Microsoft Academic Search

    R. A. Siddiqui; Hussein A. Abdullah

    2005-01-01

    The presence of hydrogen will cause damaging effects in steels and its alloys used in petroleum refineries, natural gas pipelines and oil fields. The present investigation was carried out to assess the effect of hydrogenation time, independent of other processing and other constitutional variables, on the mechanical properties of 0.31% carbon steel. The results revealed that as the exposure time

  19. Hydrogen peroxide adsorption on Fe-filled single-walled carbon nanotubes: a theoretical study.

    PubMed

    Moreno, J; Kasai, K; David, M; Nakanishi, H; Kasai, H

    2009-02-11

    We investigated the adsorption of hydrogen peroxide molecules on Fe-filled single-walled carbon nanotubes (SWNTs) based on density functional theory (DFT) calculations. The adsorption possibilities for the hydrogen peroxide molecule were tested by finding the minimum energy as a function of distance of the molecule from the Fe-filled SWNT. Stable structures were obtained by optimizing the hydrogen peroxide (H(2)O(2)) as it was adsorbed on to the Fe-filled SWNT. This study may serve as an initial investigation into the possibility of Fe-filled single-walled carbon nanotubes (SWNTs) as catalyst material for the proton exchange membrane fuel cell (PEMFC). PMID:21715921

  20. Hydrogen and elemental carbon production from natural gas and other hydrocarbons

    DOEpatents

    Detering, Brent A. (Idaho Falls, ID); Kong, Peter C. (Idaho Falls, ID)

    2002-01-01

    Diatomic hydrogen and unsaturated hydrocarbons are produced as reactor gases in a fast quench reactor. During the fast quench, the unsaturated hydrocarbons are further decomposed by reheating the reactor gases. More diatomic hydrogen is produced, along with elemental carbon. Other gas may be added at different stages in the process to form a desired end product and prevent back reactions. The product is a substantially clean-burning hydrogen fuel that leaves no greenhouse gas emissions, and elemental carbon that may be used in powder form as a commodity for several processes.

  1. Partial oxidation of methanol for hydrogen production over carbon nanotubes supported Cu-Zn catalysts

    Microsoft Academic Search

    I. Eswaramoorthi; V. Sundaramurthy; A. K. Dalai

    2006-01-01

    Carbon nanotubes (CNTs) were used as support to Cu-Zn catalysts and tested their feasibility for hydrogen production from partial oxidation of methanol. The CNTs were synthesized by CVD method using acetylene as carbon source over anodic aluminum oxide template. The structural characteristics of CNTs were analysed by SEM, TEM, XRD, Raman spectroscopy and TGA. Using these CNTs as support, Cu-Zn

  2. Migration mechanism for atomic hydrogen in porous carbon materials Badri Narayanan,1

    E-print Network

    Ciobanu, Cristian

    Migration mechanism for atomic hydrogen in porous carbon materials Badri Narayanan,1 Yufeng Zhao,2 May 2012) To explain the fast kinetics of H in porous carbon, we propose that the migration relies that the chemisorbed H atoms in car- bon migrate relatively easily, with kinetics much faster than that have been

  3. Characterization of hydrogen absorption\\/desorption states on lithium-carbon-hydrogen system by neutron diffraction

    Microsoft Academic Search

    Hiroki Miyaoka; Keiji Itoh; Toshiharu Fukunaga; Takayuki Ichikawa; Yoshitsugu Kojima; Hironobu Fuji

    2008-01-01

    The nanostructural hydrogenated graphite (CnanoHx) was synthesized from graphite by ball milling under hydrogen (H2) atmosphere. In this product, characteristic hydrogenated states in the form of polarized hydrocarbon groups (-CH, -CH2, and -CH3) are realized in the nanoscale. By synthesizing the composite of CnanoHx and lithium hydride (LiH), known as the Li-C-H system, hydrogen was desorbed at 350 °C, which

  4. Structure, hydrogen bonding and thermal expansion of ammonium carbonate monohydrate

    PubMed Central

    Fortes, A. Dominic; Wood, Ian G.; Alfè, Dario; Hernández, Eduardo R.; Gutmann, Matthias J.; Sparkes, Hazel A.

    2014-01-01

    We have determined the crystal structure of ammonium carbonate monohydrate, (NH4)2CO3·H2O, using Laue single-crystal diffraction methods with pulsed neutron radiation. The crystal is orthorhombic, space group Pnma (Z = 4), with unit-cell dimensions a = 12.047?(3), b = 4.453?(1), c = 11.023?(3)?Å and V = 591.3?(3)?Å3 [?calc = 1281.8?(7)?kg?m?3] at 10?K. The single-crystal data collected at 10 and 100?K are complemented by X-ray powder diffraction data measured from 245 to 273?K, Raman spectra measured from 80 to 263?K and an athermal zero-pressure calculation of the electronic structure and phonon spectrum carried out using density functional theory (DFT). We find no evidence of a phase transition between 10 and 273?K; above 273?K, however, the title compound transforms first to ammonium sesquicarbonate monohydrate and subsequently to ammonium bicarbonate. The crystallographic and spectroscopic data and the calculations reveal a quite strongly hydrogen-bonded structure (E HB ? 30–40?kJ?mol?1), on the basis of H?O bond lengths and the topology of the electron density at the bond critical points, in which there is no free rotation of the ammonium cation at any temperature. The barrier to free rotation of the ammonium ions is estimated from the observed librational frequency to be ??36?kJ?mol?1. The c-axis exhibits negative thermal expansion, but the thermal expansion behaviour of the a and b axes is ormal. PMID:25449618

  5. Structure, hydrogen bonding and thermal expansion of ammonium carbonate monohydrate.

    PubMed

    Fortes, A Dominic; Wood, Ian G; Alfè, Dario; Hernández, Eduardo R; Gutmann, Matthias J; Sparkes, Hazel A

    2014-12-01

    We have determined the crystal structure of ammonium carbonate monohydrate, (NH4)2CO3·H2O, using Laue single-crystal diffraction methods with pulsed neutron radiation. The crystal is orthorhombic, space group Pnma (Z = 4), with unit-cell dimensions a = 12.047?(3), b = 4.453?(1), c = 11.023?(3)?Å and V = 591.3?(3)?Å(3) [?calc = 1281.8?(7)?kg?m(-3)] at 10?K. The single-crystal data collected at 10 and 100?K are complemented by X-ray powder diffraction data measured from 245 to 273?K, Raman spectra measured from 80 to 263?K and an athermal zero-pressure calculation of the electronic structure and phonon spectrum carried out using density functional theory (DFT). We find no evidence of a phase transition between 10 and 273?K; above 273?K, however, the title compound transforms first to ammonium sesquicarbonate monohydrate and subsequently to ammonium bicarbonate. The crystallographic and spectroscopic data and the calculations reveal a quite strongly hydrogen-bonded structure (EHB ? 30-40?kJ?mol(-1)), on the basis of H...O bond lengths and the topology of the electron density at the bond critical points, in which there is no free rotation of the ammonium cation at any temperature. The barrier to free rotation of the ammonium ions is estimated from the observed librational frequency to be ??36?kJ?mol(-1). The c-axis exhibits negative thermal expansion, but the thermal expansion behaviour of the a and b axes is ormal. PMID:25449618

  6. Insight into the mechanism of the thermal reduction of graphite oxide: deuterium-labeled graphite oxide is the key.

    PubMed

    Sofer, Zden?k; Jankovský, Ond?ej; Šimek, Petr; Sedmidubský, David; Šturala, Ji?í; Kosina, Ji?í; Mikšová, Romana; Macková, Anna; Mikulics, Martin; Pumera, Martin

    2015-05-26

    For the past decade, researchers have been trying to understand the mechanism of the thermal reduction of graphite oxide. Because deuterium is widely used as a marker in various organic reactions, we wondered if deuterium-labeled graphite oxide could be the key to fully understand this mechanism. Graphite oxides were prepared by the Hofmann, Hummers, Staudenmaier, and Brodie methods, and a deuterium-labeled analogue was synthesized by the Hofmann method. All graphite oxides were analyzed not only using the traditional techniques but also by gas chromatography-mass spectrometry (GC-MS) during exfoliation in hydrogen and nitrogen atmospheres. GC-MS enabled us to compare differences between the chemical compositions of the organic exfoliation products formed during the thermal reduction of these graphite oxides. Nuclear analytical methods (Rutherford backscattering spectroscopy, elastic recoil detection analysis) were used to calculate the concentrations of light elements, including the ratio of hydrogen to deuterium. Combining all of these results we were able to determine graphite oxide's thermal reduction mechanism. Carbon dioxide, carbon monoxide, and water are formed from the thermal reduction of graphite oxide. This process is also accompanied by various radical reactions that lead to the formation of a large amount of carcinogenic volatile organic compounds, and this will have major safety implications for the mass production of graphene. PMID:25894311

  7. Deuterium in the daytime thermosphere

    NASA Technical Reports Server (NTRS)

    Breig, E. L.; Sanatani, S.; Hanson, W. B.

    1987-01-01

    Ion concentration measurements for H(+) and D(+) from the magnetic ion mass spectrometer on the Atmosphere Explorer C satellite are used, in conjunction with other atmospheric data, to determine the concentrations of H and D in the nonpolar daytime thermosphere. The ratio of the observed D(+) to H(+) concentrations has essentially the same height dependence in the 300 to 800-km region as expected for their neutral counterparts, even in the presence of ion temperature gradients and probable large vertical ion fluxes. Rapid charge exchange with atomic oxygen ensures that D/H is about equal to D(+)/H(+) at the lower altitudes where the derived D to H concentration ratio is a factor of about 6 larger than its sea level value, for an exospheric temperature of 930 K. This relative enhancement of deuterium arises from the fact that hydrogen more readily escapes the earth, and a large vertical gradient in the H concentration relative to its diffusive equilibrium value is necessary to drive this upward flux through the lower thermosphere. If these planetary losses of hydrogen are much greater than those associated with evaporative escape, as is the current view, then correspondingly larger deuterium loss rates are also likely in order that the thermospheric D/H ratio not increase well above the observed value. The absolute winter daytime concentration of deuterium at 300 km is found to be 210 + or - 50 atoms/cu cm.

  8. Merging allylic carbon-hydrogen and selective carbon-carbon bond activation

    NASA Astrophysics Data System (ADS)

    Masarwa, Ahmad; Didier, Dorian; Zabrodski, Tamar; Schinkel, Marvin; Ackermann, Lutz; Marek, Ilan

    2014-01-01

    Since the nineteenth century, many synthetic organic chemists have focused on developing new strategies to regio-, diastereo- and enantioselectively build carbon-carbon and carbon-heteroatom bonds in a predictable and efficient manner. Ideal syntheses should use the least number of synthetic steps, with few or no functional group transformations and by-products, and maximum atom efficiency. One potentially attractive method for the synthesis of molecular skeletons that are difficult to prepare would be through the selective activation of C-H and C-C bonds, instead of the conventional construction of new C-C bonds. Here we present an approach that exploits the multifold reactivity of easily accessible substrates with a single organometallic species to furnish complex molecular scaffolds through the merging of otherwise difficult transformations: allylic C-H and selective C-C bond activations. The resulting bifunctional nucleophilic species, all of which have an all-carbon quaternary stereogenic centre, can then be selectively derivatized by the addition of two different electrophiles to obtain more complex molecular architecture from these easily available starting materials.

  9. Effects of hydrogen on carbon steels at the Multi-Function Waste Tank Facility

    SciTech Connect

    Carlos, W.C.

    1995-02-08

    Concern has been expressed that hydrogen produced by corrosion, radiolysis, and decomposition of the waste could cause embrittlement of the carbon steel waste tanks at Hanford. The concern centers on the supposition that the hydrogen evolved in many of the existing tanks might penetrate the steel wall of the tank and cause embrittlement that might lead to catastrophic failure. This document reviews literature on the effects of hydrogen on the carbon steel proposed for use in the Multi-Function Waste Tank Facility for the time periods before and during construction as well as for the operational life of the tanks. The document draws several conclusions about these effects. Molecular hydrogen is not a concern because it is not capable of entering the steel tank wall. Nascent hydrogen produced by corrosion reactions will not embrittle the steel because the mild steel used in tank construction is not hard enough to be susceptible to hydrogen stress cracking and the corrosion product hydrogen is not produced at a rate sufficient to cause either loss in tensile ductility or blistering. If the steel intended for use in the tanks is produced to current technology, fabricated in accordance with good construction practice, postweld heat treated, and operated within the operating limits defined, hydrogen will not adversely affect the carbon steel tanks during their 50-year design life. 26 refs.

  10. Direct and reversible hydrogenation of CO2 to formate by a bacterial carbon dioxide reductase.

    PubMed

    Schuchmann, K; Müller, V

    2013-12-13

    Storage and transportation of hydrogen is a major obstacle for its use as a fuel. An increasingly considered alternative for the direct handling of hydrogen is to use carbon dioxide (CO2) as an intermediate storage material. However, CO2 is thermodynamically stable, and developed chemical catalysts often require high temperatures, pressures, and/or additives for high catalytic rates. Here, we present the discovery of a bacterial hydrogen-dependent carbon dioxide reductase from Acetobacterium woodii directly catalyzing the hydrogenation of CO2. We also demonstrate a whole-cell system able to produce formate as the sole end product from dihydrogen (H2) and CO2 as well as syngas. This discovery opens biotechnological alternatives for efficient CO2 hydrogenation either by using the isolated enzyme or by employing whole-cell catalysis. PMID:24337298

  11. Raman scattering and hydrogen-content analysis of amorphous hydrogenated carbon films irradiated with 200keV C sup + ions

    Microsoft Academic Search

    Leonilda A. Far-row; Barry J. Wilkens; Antoni S. Gozdz; Derrick L. Hart

    1990-01-01

    Amorphous hydrogenated diamondlike'' carbon films ({ital a}-C:H) have been modified by bombardment with 200-keV C{sup +} ions at four doses ranging from 10¹⁴ to 10¹⁷ cm⁻². Ratios of carbon to hydrogen in the resulting samples have been determined with use of elastic recoil detection (ERD) and Rutherford backscattering (RBS); hydrogen content is significantly reduced as the dose is increased. Raman

  12. Thermally Controlled Hydrogen Storage System Using Novel Carbon Materials

    Microsoft Academic Search

    L. L. Vasiliev; L. E. Kanonchik; V. A. Babenko

    Successful development of sorption storage technologies for hydrogen assumes an active temperature control and special properties\\u000a of the materials, capable to adsorb hydrogen in a reversible way.\\u000a \\u000a The goal of this paper is the development of the sectional vessel with heat pipe (HP) for hydrogen sorption storage at average\\u000a pressures 3.5–6 MPa, every separate section of which has the case

  13. PUBLISHED VERSION Single crystal diamond detector measurements of deuterium-deuterium and deuterium-tritium

    E-print Network

    PUBLISHED VERSION Single crystal diamond detector measurements of deuterium-deuterium and deuterium-tritium detector measurements of deuterium-deuterium and deuterium- tritium neutrons in Joint European Torus fusion study of DT plasmas heated with tritium neutral beams Rev. Sci. Instrum. 72, 832 (2001); 10

  14. Preparation and characterization of ordered porous carbons for increasing hydrogen storage behaviors

    SciTech Connect

    Lee, Seul-Yi [Department of Chemistry, Inha University, 253 Nam-gu, Incheon 402-751 (Korea, Republic of); Park, Soo-Jin, E-mail: sjpark@inha.ac.kr [Department of Chemistry, Inha University, 253 Nam-gu, Incheon 402-751 (Korea, Republic of)

    2011-10-15

    We prepared ordered porous carbons (PCs) by using a replication method that had well-organized mesoporous silica as a template with various carbonization temperatures in order to investigate the possibility of energy storage materials. The microstructure and morphologies of the samples are characterized by XRD, TEM, and FT-Raman spectroscopy. N{sub 2} adsorption isotherms are analyzed by the t-plot method, as well as the BET and the H-K method in order to characterize the specific surface area, pore volume, and pore size distribution of the samples, respectively. The capacity of the hydrogen adsorption of the samples is evaluated by BEL-HP at 77 K and 1 bar. From the results, we are able to confirm that the synthesis of the samples can be accurately governed by the carbonization temperature, which is one of the effective parameters for developing the textural properties of the carbon materials, which affects the behaviors of the hydrogen storage. - Graphical abstract: It is described that the considerable long-range ordering and the presence of mono-dimensional aligned channels between the two aligned nanorods of the porous framework from the SBA-15 was retained in the T-950 sample during the carbonization process. Highlights: > Ordered porous carbons (PCs) are synthesized with various carbonization temperatures by using a replication method. > Carbonization temperature plays an important role in shrinking the micropores during the carbonization process of PCs. > The textural and structural properties of the PCs are good parameters for enhancing the hydrogen storage capacity.

  15. Shock Compression of Deuterium and the Interiors of Jupiter and Saturn

    Microsoft Academic Search

    D. Saumon; T. Guillot

    2004-01-01

    Recently, deuterium has been the focus of a high level of experimental and theoretical activity, sparked by a disagreement on the experimental value of the maximum compression along the principal Hugoniot. The behavior of deuterium at megabar pressures is not well understood. It is of great interest to understand how the current uncertainty on the hydrogen\\/deuterium equation of state (EOS)

  16. Passive Colorimetric Dosimeter Tubes for Ammonia, Carbon Monoxide, Carbon Dioxide, Hydrogen Sulfide, Nitrogen Dioxide and Sulfur Dioxide

    Microsoft Academic Search

    PAUL W. McCONNAUGHEY; ELMER S. McKEE; IRVIN M. PRITTS

    1985-01-01

    Colorimetric, stain length, personal dosimeters operating by gas diffusion have been developed to determine worker exposure for up to an eight-hour period for several inorganic airborne contaminants in the range of their Threshold Limit Values. Length of stain, colorimetric dosimeters have been made for the detection of ammonia (NH3), carbon monoxide (CO), carbon dioxide (CO2), hydrogen sulfide (H2S), nitrogen dioxide

  17. Manufacture of a gas containing carbon monoxide and hydrogen gas from a starting material containing carbon and/or hydrocarbon

    SciTech Connect

    Santen, S.; Johansson, B.

    1984-08-21

    In a process for manufacturing a gas substantially containing carbon monoxide and hydrogen gas from a starting material containing carbon and/or hydrocarbon, the starting material is injected in powder or liquid form together with an oxidizing agent and slag former in a combustion zone while heat energy is simultaneously supplied. The combustion zone is formed in the lower portion of a shaft filled with particulate, solid, carbonaceous material and sulphur-binding slag former.

  18. Preparation of Amorphous Hydrogenated Carbon Films by RF Sputtering at a Low-Hydrogen-Flow-Rate Region for Hydrogen-Reactive Substrates

    NASA Astrophysics Data System (ADS)

    Oshiro, Takehiko; Yamazato, Masaaki; Higa, Akira; Maehama, Takehiro; Toguchi, Minoru

    2004-05-01

    Amorphous hydrogenated carbon (a-C:H) films have been deposited by RF magnetron sputtering system in H2/He plasma. Hydrogen incorporated into the a-C:H film plays an important role in the release of internal stress in the film. On the other hand, hydrogen plasma has deoxidizing, etching and reduction effects on a substrate. Some oxides and compound semiconductors such as CdTe substrate receive serious damage during the deposition process of a-C:H film. Therefore, the amount of hydrogen radicals in sputtering plasma should be as small as possible for suppressing the damage. In this study, we investigate the effects of hydrogen incorporated to an a-C:H film which are deposited at a wide range of relative hydrogen gas flow rate (RH) from 0.1% to 50%. It has been clarified that the a-C:H films deposited in low RH have high quality and that the films can be grown on a CdTe substrate without etching by hydrogen ions and radicals at RH=0.2% and the nearest-neighbor region.

  19. Spitzer Observations of Shock-excited Hydrogen Deuteride in IC 443C, HH 7, and HH 54: Probing the Gas-phase Deuterium Abundance in the Dense Interstellar Medium

    NASA Astrophysics Data System (ADS)

    Yuan, Yuan; Neufeld, David A.; Sonnentrucker, Paule; Melnick, Gary J.; Watson, Dan M.

    2012-07-01

    We present and analyze observations—carried out using the Infrared Spectrograph (IRS) on the Spitzer Space Telescope—of the R(3) and R(4) pure rotational lines of hydrogen deuteride (HD) detected from shock-heated material associated with the supernova remnant IC 443C and with the Herbig-Haro objects HH 7 and HH 54. Assuming a continuous temperature distribution for gas observed along the sight lines, we have constrained the gas density to be in the ~103-104 cm-3 range, using both spectroscopic data for H2, HD, and CO from IRS and from the Infrared Space Observatory (ISO), as well as photometric data from Spitzer's Infrared Array Camera. The derived HD abundance relative to H2 is quite sensitive to the assumed excitation conditions in the emitting gas. Assuming that HD accounts for all gas-phase deuterium in the emitting material, and using all the available spectroscopic data to constrain the excitation conditions, we obtained gas-phase deuterium abundances [D/H]gas of 0.95+0.54 -0.27 × 10-5 and 0.87+0.31 -0.27 × 10-5 (statistical errors only) for IC 443C and HH 54, respectively. The uncertainties in the HD abundance are dominated by systematic effects related to the poorly known excitation conditions, and more accurate estimates of the HD abundance in shocked molecular clouds will require measurements of the emission in additional HD rotational transitions.

  20. Hydrogen desorption properties of multiwall carbon nanotubes with closed and open structures

    NASA Astrophysics Data System (ADS)

    Lee, Ho; Kang, Youn-Seon; Kim, Seoung-Hoe; Lee, Jai-Young

    2002-01-01

    The multiwall carbon nanotubes (MWNTs) synthesized by microwave plasma enhanced chemical vapor deposition in 0.1% CH4 (H2 dilution) reaction gas were shaped in curly structures with the blocked nanoholes and closed caps. On the contrary, the carbon nanotubes with different structures could be obtained in oxygen loaded reaction gas, showing aligned structures with connected holes and open caps. The hydrogen desorption properties of the carbon nanotubes (CNTs) with these closed and open structures were compared by thermal desorption technique. The MWNTs with closed structure desorbed hydrogen at two different temperature ranges such as 290-330 and ˜420 K, where the evolved hydrogen amount were ˜0.64 and ˜0.03 wt %, respectively. In case of aligned and open MWNTs, hydrogen as high as ˜1.97 wt % was released at ambient temperature. The hydrogen desorption of MWNTs with open and closed structure at ambient temperature showed the hydrogen desorption activation energies of -16.5 kJ/mol H2 and -18.5 kJ/mol H2, respectively. The high temperature hydrogen desorption observed only in CNTs with closed and highly defective structure was high desorption activation energy of -124.4 kJ/mol.

  1. Continuous monitoring of hydrogen and carbon dioxide at Stromboli volcano

    NASA Astrophysics Data System (ADS)

    Di Martino, Roberto M. R.; Camarda, Marco; Gurrieri, Sergio; Valenza, Mariano

    2015-04-01

    Geochemical monitoring of fumarole and soil gases is a powerful tool for volcano surveillance, for investigating the subsurface magma dynamics, and for hazard assessment in volcanic areas. The monitoring of both carbon dioxide (CO2) flux, and hydrogen (H2) concentration in active volcanic areas helps to improve the understanding of the processes linking the surface gas emissions, the chemistry of the magmatic gases, and the volcanic activity. The CO2 flux measurement is a routine technique for volcano monitoring purposes, because of CO2 is the second-abundant component of the gas phase in silicate magmas, attaining saturation at the mantle to deep crustal level. The H2 concentration has provided indications concerning the oxygen fugacity of magmatic gases, a parameter that changes over a wide range of low values (10-16 - 10-8 bar), and affects the redox state of multivalent elements. This study reports on the use a tailor-made automatic system developed for continuous monitoring purposes of H2 concentration and CO2 flux in the summit area of Stromboli volcano (Aeolian islands). The automatic device consists of an H2-selective electrochemical sensor, and two IR-spectrophotometers for measuring the CO2 flux in agreement with the dynamic concentration method. The data collected by the automatic system deployed at Stromboli from 19 May 2009 to 15 December 2010 are presented herein. The data processing provides a better understanding of the relationships between the evolution of the low temperature fumarolic emissions, and the volcanic activity. The results of the data analysis indicates that the high frequency variations exhibited by CO2 flux and H2 concentration are positively correlated with the eruptive activity of Stromboli, typically changing on time scale of hours or days. Furthermore, the investigation of the relationships between CO2 flux and H2 concentration provides an evaluation of the depth of the degassing source, by which the gas mixture containing H2 and CO2 starts to move through the rock fractures. Our data indicates that the depth of the degassing source ranges between 2 and 4 km in the volcano plumbing system, in agreement with the magma storage zone that has been proposed by other geochemical, volcanological, petrological and geophysical investigations.

  2. Transition metal activation and functionalization of carbon-hydrogen bonds

    SciTech Connect

    Jones, W.D.

    1992-06-01

    We are investigating the fundamental thermodynamic and kinetic factors that influence carbon-hydrogen bond activation at homogeneous transition metal centers and the conversion of hydrocarbons into functionalized products of potential use to the chemical industry. Advances have been made in both understanding the interactions of hydrocarbons with metals and in the functionalization of hydrocarbons. We have found that RhCl(PR{sub 3}){sub 2}(CNR) complexes can catalyze the insertion of isonitriles into the C-H bonds or arenes upon photolysis. The mechanism of these reactions was found to proceed by way of initial phosphine dissociation, followed by C-H activation and isonitrile insertion. We have also examined reactions of a series of arenes with (C{sub 5}Me{sub 5})Rh(PMe{sub 3})PhH and begun to map out the kinetic and thermodynamic preferences for arene coordination. The effects of resonance, specifically the differences in the Hueckel energies of the bound vs free ligand, are now believed to fully control the C-H activation/{eta}{sup 2}-coordination equilibria. We have begun to examine the reactions of rhodium isonitrile pyrazolylborates for alkane and arene C-H bond activation. A new, labile, carbodiimide precursor has been developed for these studies. We have completed studies of the reactions of (C{sub 5}Me{sub 5})Rh(PMe{sub 3})H{sub 2} with D{sub 2} and PMe{sub 3} that indicate that both {eta}{sup 5} {yields} {eta}{sup 3} ring slippage and metal to ring hydride migration occur more facilely than thermal reductive elimination of H{sub 2}. We have examined the reactions of heterocycles with (C{sub 5}Me{sub 5})Rh(PMe{sub 3})PhH and found that pyrrole and furan undergo C-H or N-H activation. Thiophene, however, undergoes C-S bond oxidative addition, and the mechanism of activation has been shown to proceed through sulfur coordination prior to C-S insertion.

  3. Effects of Microstructure of Carbon Nanofibers for Amperometric Detection of Hydrogen Peroxide

    SciTech Connect

    Li, Zhizhou; Cui, Xiaoli; Zheng, Junsheng; Wang, Qingfei; Lin, Yuehe

    2007-08-10

    Carbon nanofibers (CNFs) with different microstructures, including platelet-carbon nanofibers (PCNFs), fish-bone-carbon nanofibers (FCNFs), and tube-carbon nanofibers (TCNFs), were synthesized, characterized, and evaluated for electrochemical sensing of hydrogen peroxide. The CNFs studied here can show several microstructures in which various stacked morphologies and their sizes and graphite-layer ordering can be well controlled. Glassy carbon (GC) electrodes modified by CNFs were fabricated and compared for amperometric detection of hydrogen peroxide. Sensors of PCNFs/GC, FCNFs/GC, and TCNFs/GC were used in the amperometric detection of H2O2 in a solution of 0.05 M phosphate buffered saline solution (pH 7.4).

  4. Conformational changes of the glucocorticoid receptor ligand binding domain induced by ligand and cofactor binding, and the location of cofactor binding sites determined by hydrogen/deuterium exchange mass spectrometry

    PubMed Central

    Frego, Lee; Davidson, Walter

    2006-01-01

    HXMS (hydrogen/deuterium exchange mass spectrometry) of the glucocorticoid receptor ligand-binding domain (GR LBD) complexed with the agonist dexamethasone and the antagonist RU-486 is described. Variations in the rates of exchange were observed in regions consistent with the published crystal structures of GR LBD complexed with RU-486 when compared with the GR dexamethasone complex. We also report the HXMS results for agonist-bound GR LBD with the coactivator transcriptional intermediary factor 2 (TIF2) and anatagonist-bound GR LBD with nuclear receptor corepressor (NCoR). Alterations in exchange rates observed for agonist-bound GR LBD with TIF2 present were consistent with the published crystal structural contacts for the complex. Alterations in exchange rates observed for antagonist-bound GR LBD with NCoR were a subset of those observed with TIF2 binding, suggesting a common or overlapping binding site for coactivator and corepressor. PMID:16600964

  5. Process for producing methane from gas streams containing carbon monoxide and hydrogen

    DOEpatents

    Frost, Albert C. (Congers, NY)

    1980-01-01

    Carbon monoxide-containing gas streams are passed over a catalyst capable of catalyzing the disproportionation of carbon monoxide so as to deposit a surface layer of active surface carbon on the catalyst essentially without formation of inactive coke thereon. The surface layer is contacted with steam and is thus converted to methane and CO.sub.2, from which a relatively pure methane product may be obtained. While carbon monoxide-containing gas streams having hydrogen or water present therein can be used only the carbon monoxide available after reaction with said hydrogen or water is decomposed to form said active surface carbon. Although hydrogen or water will be converted, partially or completely, to methane that can be utilized in a combustion zone to generate heat for steam production or other energy recovery purposes, said hydrogen is selectively removed from a CO--H.sub.2 -containing feed stream by partial oxidation thereof prior to disproportionation of the CO content of said stream.

  6. Single Pd atoms in activated carbon fibers and their contribution to hydrogen storage

    SciTech Connect

    Contescu, Cristian I [ORNL; van Benthem, Klaus [ORNL; Li, Sa [Virginia Commonwealth University, Richland; Bonifacio, Cecile S [University of California, Davis; Pennycook, Stephen J [ORNL; Jena, Puru [Virginia Commonwealth University, Richland; Gallego, Nidia C [ORNL

    2011-01-01

    Palladium-modified activated carbon fibers (Pd-ACF) were synthesized by meltspinning, carbonization and activation of an isotropic pitch carbon precursor premixed with an organometallic Pd compound. The hydrogen uptake at 25 oC and 20 bar on Pd- ACF exceeded the expected capacity based solely on Pd hydride formation and hydrogen physisorption on the microporous carbon support. Aberration-corrected scanning transmission electron microscopy (STEM) with sub- ngstrom spatial resolution provided unambiguous identification of isolated Pd atoms occurring in the carbon matrix that coexist with larger Pd particles. First principles calculations revealed that each single Pd atom can form Kubas-type complexes by binding up to three H2 molecules in the pressure range of adsorption measurements. Based on Pd atom concentration determined from STEM images, the contribution of various mechanisms to the excess hydrogen uptake measured experimentally was evaluated. With consideration of Kubas binding as a viable mechanism (along with hydride formation and physisorption to carbon support) the role of hydrogen spillover in this system may be smaller than previously thought.

  7. Hydrogen-bond acidic functionalized carbon nanotubes (CNTs) with covalently-bound hexafluoroisopropanol groups

    SciTech Connect

    Fifield, Leonard S.; Grate, Jay W.

    2010-06-01

    Fluorinated hydrogen-bond acidic groups are directly attached to the backbone of single walled carbon nanotubes (SWCNTs) without the introduction of intermediate electron donating surface groups. Hexafluoroalcohol functional groups are exceptionally strong hydrogen bond acids, and are added to the nanotube surface using the aryl diazonium approach to create hydrogen-bond acidic carbon nanotube (CNT) surfaces. These groups can promote strong hydrogen-bonding interactions with matrix materials in composites or with molecular species to be concentrated and sensed. In the latter case, this newly developed material is expected to find useful application in chemical sensors and in CNT-based preconcentrator devices for the detection of pesticides, chemical warfare agents and explosives.

  8. Spot-free catalysis using gold carbon nanotube & gold graphene composites for hydrogen evolution reaction

    NASA Astrophysics Data System (ADS)

    Sai Siddhardha, R. S.; Lakshminarayanan, V.; Ramamurthy, Sai Sathish

    2015-08-01

    Hydrogen has been proposed as the green fuel of the future in the wake of depleting fossil fuels. Recently, carbon paste electrodes (CPE) modified with nanomaterials as electrocatalysts have drawn wide attention for hydrogen evolution reaction (HER) in acid medium. The CPEs are advantageous owing to their chemical stability and ease of fabrication. Their applications for HER without any modification, however, are hampered on account of large hydrogen overpotential associated with carbon surface. In the present study, CPE has been modified with novel gold composites as electro-catalysts for HER in acid medium. The nanocomposites have shown ?100 fold increased current density than unmodified CPE at -0.3 V. Most strikingly for the first time, this study has quantitatively brought out the difference in catalysis between surfactant capped and pristine gold nanoparticles in terms of their application as spot-free catalysts towards hydrogen gas production by electrochemical route.

  9. Compound-specific carbon, nitrogen, and hydrogen isotopic ratios for amino acids in CM and CR chondrites and their use in evaluating potential formation pathways

    NASA Astrophysics Data System (ADS)

    Elsila, Jamie E.; Charnley, Steven B.; Burton, Aaron S.; Glavin, Daniel P.; Dworkin, Jason P.

    2012-09-01

    Stable hydrogen, carbon, and nitrogen isotopic ratios (?D, ?13C, and ?15N) of organic compounds can reveal information about their origin and formation pathways. Several formation mechanisms and environments have been postulated for the amino acids detected in carbonaceous chondrites. As each proposed mechanism utilizes different precursor molecules, the isotopic signatures of the resulting amino acids may indicate the most likely of these pathways. We have applied gas chromatography with mass spectrometry and combustion isotope ratio mass spectrometry to measure the compound-specific C, N, and H stable isotopic ratios of amino acids from seven CM and CR carbonaceous chondrites: CM1/2 Allan Hills (ALH) 83100, CM2 Murchison, CM2 Lewis Cliff (LEW) 90500, CM2 Lonewolf Nunataks (LON) 94101, CR2 Graves Nunataks (GRA) 95229, CR2 Elephant Moraine (EET) 92042, and CR3 Queen Alexandra Range (QUE) 99177. We compare the isotopic compositions of amino acids in these meteorites with predictions of expected isotopic enrichments from potential formation pathways. We observe trends of decreasing ?13C and increasing ?D with increasing carbon number in the ?-H, ?-NH2 amino acids that correspond to predictions made for formation via Strecker-cyanohydrin synthesis. We also observe light ?13C signatures for ?-alanine, which may indicate either formation via Michael addition or via a pathway that forms primarily small, straight-chain, amine-terminal amino acids (n-?-amino acids). Higher deuterium enrichments are observed in ?-methyl amino acids, indicating formation of these amino acids or their precursors in cold interstellar or nebular environments. Finally, individual amino acids are more enriched in deuterium in CR chondrites than in CM chondrites, reflecting different parent-body chemistry.

  10. Principles and mechanism of combustion in the zirconium-carbon-hydrogen system

    SciTech Connect

    Martirosyan, N.A.; Dolvkhanyan, S.K.; Merzhanov, A.G.

    1986-03-01

    The authors examine the principles and mechanism of combustion in the Zr-C-H/sub 2/ system in order to clarify the generality of the effects observed previously. The experiments were performed in a constant-pressure vessel with type M-41 powdered zirconium, carbon black, and gaseous hydrogen. Chemical analysis was performed for the total and free contents of carbon, zirconium and hydrogen, and x-ray studies were performed using a DRON-0.5 analyzer. In the Zr-C-H/sub 2/ system the general tendency inherent in Me-C-H/sub 2/ systems toward completion of the hydrogenation and carbonization reactions is maintained. In this mixture, as in Ti-C-H/sub 2/, the steady-state combustion regimes are not the same when ignition sources of different temperatures are used.

  11. Dissociation of CH4 by electron impact: Production of metastable hydrogen and carbon fragments

    NASA Technical Reports Server (NTRS)

    Finn, T. G.; Carnahan, B. L.; Zipf, E. C.

    1974-01-01

    Metastable fragments produced by electron impact excitation of CH4 have been investigated for incident electron energies from threshold to 300 eV. Only metastable hydrogen and carbon atoms were observed. Onset energies for the production of metastable hydrogen atoms were observed at electron impact energies of 22.0 + or - .5 eV, 25.5 + or - .6 eV, 36.7 + or - .6 eV and 66 + or - 3 eV, and at 26.6 + or - .6 eV for the production of metastable carbon atoms. Most of the fragments appear to have been formed in high-lying Rydberg states. The total metastable hydrogen cross section reaches a maximum value of approximately 1 X 10 to the minus 18th power sq cm at 100 eV. At the same energy, the metastable carbon cross section is 2 x 10 to the minus 19th power sq cm.

  12. Dynamic and Thermodynamic Behavior of Carboneous and Hydrogen-Bonding Materials

    SciTech Connect

    Ree, F.H.; Galli, G.; Glosli, J.N.; Gygi, F.; Schwegler, E.; Viecelli, J.A.; Winter, N.W.

    2000-02-04

    Dissociation behavior of carboneous materials with or without fluorine atoms at pressures (P) of tens of gigapascal (GPa) and temperature (T) at several thousand Kelvin is not so well understood. The main issues are: (a) carbon condensation processes and (b) thermodynamics of hydrogen fluoride (HF) produced from dissociation. Item (a) requires information on (i) the melting line of carbon, (ii) liquid carbon, (iii) stability and energy barrier between graphite and diamond clusters, and (iv) kinetics of cluster growth. Item (b) requires knowledge of (v) intermolecular potentials involving HF and (vi) influence of fluorine chemistry on supercritical phase change. The details concerning these issues are described.

  13. Atomic structure and physical properties of amorphous carbon and its hydrogenated analogs

    Microsoft Academic Search

    Th. Frauenheim; P. Blaudeck; U. Stephan; G. Jungnickel

    1993-01-01

    A semiempirical molecular-dynamic density-functional approach is used to perform a systematic investigation of the stability, structure, and properties of quenched pure and hydrogenated amorphous carbon dependent on the mass density and the hydrogen concentration. By comparing the total structure energies for supercell clusters of equal composition and atom number, we obtain the most stable a-C:H configurations characterized by optimal chemical

  14. Evaluation of the isosteric heat of adsorption at zero coverage for hydrogen on activated carbons

    NASA Astrophysics Data System (ADS)

    Dohnke, E.; Beckner, M.; Romanos, J.; Olsen, R.; Wexler, C.; Pfeifer, P.

    2011-03-01

    Activated carbons made from corn cob show promise as materials for high-capacity hydrogen storage. As part of our characterization of these materials, we are interested in learning how different production methods affect the adsorption energies. In this talk, we will show how hydrogen adsorption isotherms may be used to calculate these adsorption energies at zero coverage using Henry's law. We will additionally discuss differences between the binding energy and the isosteric heat of adsorption by applying this analysis at different temperatures.

  15. Relation of Hydrogen and Methane to Carbon Monoxide in Exhaust Gases from Internal-Combustion Engines

    NASA Technical Reports Server (NTRS)

    Gerrish, Harold C; Tessmann, Arthur M

    1935-01-01

    The relation of hydrogen and methane to carbon monoxide in the exhaust gases from internal-combustion engines operating on standard-grade aviation gasoline, fighting-grade aviation gasoline, hydrogenated safety fuel, laboratory diesel fuel, and auto diesel fuel was determined by analysis of the exhaust gases. Two liquid-cooled single-cylinder spark-ignition, one 9-cylinder radial air-cooled spark-ignition, and two liquid-cooled single-cylinder compression-ignition engines were used.

  16. Enhanced hydrogen production from biomass with in situ carbon dioxide capture using calcium oxide sorbents

    Microsoft Academic Search

    Nicholas H. Florin; Andrew T. Harris

    2008-01-01

    The steam gasification of biomass, in the presence of a calcium oxide (CaO) sorbent for carbon dioxide (CO2) capture, is a promising pathway for the renewable and sustainable production of hydrogen (H2). In this work, we demonstrate the potential of using a CaO sorbent to enhance hydrogen output from biomass gasifiers. In addition, we show that CaO materials are the

  17. Experimental and theoretical study of the carbon-13 and deuterium kinetic isotope effects in the Cl and OH reactions of CH3F.

    PubMed

    Marinkovic, Marina; Gruber-Stadler, Margret; Nicovich, J Michael; Soller, Raenell; Mülhäuser, Max; Wine, Paul H; Bache-Andreassen, Lihn; Nielsen, Claus J

    2008-12-01

    A laser flash photolysis-resonance fluorescence technique has been employed to determine absolute rate coefficients for the CH3F + Cl reaction in N2 bath gas in the temperature range of 200-700 K and pressure range of 33-133 hPa. The data were fitted to a modified Arrhenius expression k(T) = 1.14 x 10(-12) x (T/298)2.26 exp{-313/T}. The OH and Cl reaction rates of (13)CH3F and CD3F have been measured by long-path FTIR spectroscopy relative to CH3F at 298 +/- 2 K and 1013 +/- 10 hPa in purified air. The FTIR spectra were fitted using a nonlinear least-squares spectral fitting method including line data from the HITRAN database and measured infrared spectra as references. The relative reaction rates defined by alpha = k(light)/k(heavy) were determined to be k(OH+CH3F)/k(OH+CD3F) = 4.067 +/- 0.018, k(OH+CH3F)/k(OH+(13)CH3F) = 1.067 +/- 0.006, k(Cl+CH3F)/k(Cl+CD3F) = 5.11 +/- 0.07, and k(Cl+CH3F)/k(Cl+(13)CH3F) = 1.016 +/- 0.006. The carbon-13 and deuterium kinetic isotope effects in the OH and Cl reactions of CH3F have been further investigated by quantum chemistry methods and variational transition state theory. PMID:18989948

  18. Optimizing the Binding Energy of Hydrogen on Nanostructured Carbon Materials through Structure Control and Chemical Doping

    SciTech Connect

    Jie Liu

    2011-02-01

    The DOE Hydrogen Sorption Center of Excellence (HSCoE) was formed in 2005 to develop materials for hydrogen storage systems to be used in light-duty vehicles. The HSCoE and two related centers of excellence were created as follow-on activities to the DOE Office of Energy Efficiency and Renewable Energy’s (EERE’s) Hydrogen Storage Grand Challenge Solicitation issued in FY 2003. The Hydrogen Sorption Center of Excellence (HSCoE) focuses on developing high-capacity sorbents with the goal to operate at temperatures and pressures approaching ambient and be efficiently and quickly charged in the tank with minimal energy requirements and penalties to the hydrogen fuel infrastructure. The work was directed at overcoming barriers to achieving DOE system goals and identifying pathways to meet the hydrogen storage system targets. To ensure that the development activities were performed as efficiently as possible, the HSCoE formed complementary, focused development clusters based on the following four sorption-based hydrogen storage mechanisms: 1. Physisorption on high specific surface area and nominally single element materials 2. Enhanced H2 binding in Substituted/heterogeneous materials 3. Strong and/or multiple H2 binding from coordinated but electronically unsatruated metal centers 4. Weak Chemisorption/Spillover. As a member of the team, our group at Duke studied the synthesis of various carbon-based materials, including carbon nanotubes and microporous carbon materials with controlled porosity. We worked closely with other team members to study the effect of pore size on the binding energy of hydrogen to the carbon –based materials. Our initial project focus was on the synthesis and purification of small diameter, single-walled carbon nanotubes (SWNTs) with well-controlled diameters for the study of their hydrogen storage properties as a function of diameters. We developed a chemical vapor deposition method that synthesized gram quantities of carbon nanotubes with average diameter size at less than 1 nm. However, initial tests performed at our collaborator’s lab at the National Renewable Energy Laboratory (NREL) did not indicate improved hydrogen sorption properties for the smaller-diameter nanotubes (compared with other types of nanotubes). As work continued, the difficulties in purification, large-scale synthesis, and stability of small diameter SWNTs became a major concern. In 2008, the Department of Energy (DOE) made a no-go decision on future applied R&D investment in pure, undoped, single-walled carbon nanotubes for vehicular hydrogen storage.2 The second phase of the project involved developing a low-cost and scalable approach for the synthesis of microporous carbon materials with well-controlled pore sizes that would be suitable for hydrogen storage. The team studied several approaches, including the use of different zeolites as a template, the use of organic micelle structures as a template, and the slow oxidation of polymer precursors. Among them, the slow activation of Polyether ether ketone (PEEK) under either CO2 environment or H2O vapor produced microporous carbon with an average pore size of less than 2 nm. Initial testing at 77K at both NREL and the California Institute of Technology (CalTech) showed that these materials can store ~5.1 wt% hydrogen (excess) at 40 bar and 77K. The main feature to note with this material is that while the excess gravimetric capacities (>5 wt% at 77K) and specific surface areas (>3100 m2/g) are similar to AX-21 and other “super activated” commercial carbon sorbents at the same temperatures and pressures, due to the smaller pore sizes, bulk densities greater than 0.7 g/ml can be achieved, enabling excess volumetric capacities greater than 35 g/L; more than double that of AX-21.

  19. Hydrogenated carbon nanotubes: x-ray absorption spectroscopy and ab initio simulation analysis

    NASA Astrophysics Data System (ADS)

    Brzhezinskaya, M.; Yalovega, G.; Shmatko, V.; Klyushin, A.; Bogoslavskaya, E.; Krestinin, A.; Bashkin, I.

    2013-04-01

    The paper presents the results of investigation of the chemical bond formation in hydrogenated single-walled carbon nanotubes using X-ray absorption spectroscopy. All measurements were performed with the use of synchrotron radiation at BESSY II. The C1s absorption spectra point to formation of covalent chemical bonding between the hydrogen and carbon atoms in H-SWNTs. The investigation of the H-SWNT local structure has been carried out on the basis of the semi-empirical PM6 method (MOPAC 2009) and Finite Difference method. The possibility of H-SWNTs dehydrogenation was also investigated.

  20. Stable hydrogen and carbon isotope ratios of extractable hydrocarbons in the Murchison meteorite

    NASA Technical Reports Server (NTRS)

    Krishnamurthy, R. V.; Epstein, S.; Pizzarello, S.; Cronin, J. R.; Yuen, G. U.

    1991-01-01

    A fairly fool-proof method to ensure that the compounds isolated from meteorites are truly part of the meteorites and not an artifact introduced by exposure to the terrestrial environment, storage, or handling is presented. The stable carbon and hydrogen isotope ratios in several of the chemical compounds extracted from the Murchison meteorite were measured. The results obtained by studying the amino acids in this meteorite gave very unusual hydrogen and carbon isotope ratios. The technique was extended to the different classes of hydrocarbons and the hydrocarbons were isolated using a variety of separation techniques. The results and methods used in this investigation are described in this two page paper.

  1. Microwave absorption by hydrogen plasma in carbon nanotubes films with layered dielectric structure

    NASA Astrophysics Data System (ADS)

    Peng, Zhihua; Liu, Baoxing; Peng, Yanfeng; Jia, Peng; Zhan, Xiaogui; Xie, Ningyu

    2015-05-01

    A layered structure model is proposed for microwave dielectric properties of nonhomogeneous hydrogen plasma in carbon nanotubes (CNTs) film. Using the transfer matrix method for solving electromagnetic wave propagation equation, the microwave attenuation of the film is calculated in the range of 0-30 GHz under different conditions. It is found theoretically that with the increase of hydrogen plasma nonhomogeneity, the frequency bandwidth of strong microwave absorption by the film increases markedly. The application of a moderate static magnetic field can effectively improve microwave attenuation properties of hydrogen plasma in CNTs. The numerical results are in good agreement with the available experimental data.

  2. LITERATURE SURVEY OF GASEOUS HYDROGEN EFFECTS ON THE MECHANICAL PROPERTIES OF CARBON AND LOW ALLOY STEELS

    SciTech Connect

    Lam, P; Andrew Duncan, A; Robert Sindelar, R; Thad Adams, T

    2009-04-27

    Literature survey has been performed for a compendium of mechanical properties of carbon and low alloy steels following hydrogen exposure. The property sets include yield strength, ultimate tensile strength, uniform elongation, reduction of area, threshold stress intensity factor, fracture toughness, and fatigue crack growth. These properties are drawn from literature sources under a variety of test methods and conditions. However, the collection of literature data is by no means complete, but the diversity of data and dependency of results in test method is sufficient to warrant a design and implementation of a thorough test program. The program would be needed to enable a defensible demonstration of structural integrity of a pressurized hydrogen system. It is essential that the environmental variables be well-defined (e.g., the applicable hydrogen gas pressure range and the test strain rate) and the specimen preparation be realistically consistent (such as the techniques to charge hydrogen and to maintain the hydrogen concentration in the specimens).

  3. LITERATURE SURVEY OF GASEOUS HYDROGEN EFFECTS ON THE MECHANICAL PROPERTIES OF CARBON AND LOW ALLOY STEELS

    SciTech Connect

    Lam, P; Robert Sindelar, R; Thad Adams, T

    2007-04-18

    Literature survey has been performed for a compendium of mechanical properties of carbon and low alloy steels following hydrogen exposure. The property sets include yield strength, ultimate tensile strength, uniform elongation, reduction of area, threshold stress intensity factor, fracture toughness, and fatigue crack growth. These properties are drawn from literature sources under a variety of test methods and conditions. However, the collection of literature data is by no means complete, but the diversity of data and dependency of results in test method is sufficient to warrant a design and implementation of a thorough test program. The program would be needed to enable a defensible demonstration of structural integrity of a pressurized hydrogen system. It is essential that the environmental variables be well-defined (e.g., the applicable hydrogen gas pressure range and the test strain rate) and the specimen preparation be realistically consistent (such as the techniques to charge hydrogen and to maintain the hydrogen concentration in the specimens).

  4. Renewable Hydrogen Carrier Carbohydrate: Constructing the Carbon-Neutral Carbohydrate Economy

    SciTech Connect

    Zhang, Y.-H. Percival [Virginia Polytechnic Institute and State University (Virginia Tech); Mielenz, Jonathan R [ORNL

    2011-01-01

    Abstract The hydrogen economy presents an appealing energy future but its implementation must solve numerous problems ranging from low-cost sustainable production, high-density storage, costly infrastructure, to eliminating safety concern. The use of renewable carbohydrate as a high-density hydrogen carrier and energy source for hydrogen production is possible due to emerging cell-free synthetic biology technology called cell-free synthetic pathway biotransformation (SyPaB). Assembly of numerous enzymes and co-enzymes in vitro can create complicated set of biological reactions or pathways that microorganisms cannot complete, for example, C6H10O5 (aq) + 7 H2O (l) 12 H2 (g) + 6 CO2 (g) (PLoS One 2007, 2:e456). Thanks to 100% selectivity of enzymes, modest reaction conditions, and high-purity of generated hydrogen, carbohydrate is a promising hydrogen carrier for end users. Gravimetric density of carbohydrate is 14.8 H2 mass% if water can be recycled from PEM fuel cells or 8.33% H2 mass% without water recycling. Renewable carbohydrate can be isolated from plant biomass or would be produced from a combination of solar electricity/hydrogen and carbon dioxide fixation mediated by high-efficiency artificial photosynthesis mediated by SyPaB. The construction of this carbon-neutral carbohydrate economy would address numerous sustainability challenges, such as electricity and hydrogen storage, CO2 fixation and long-term storage, water conservation, transportation fuel production, plus feed and food production.

  5. Hydrogenation of PAH molecules through interaction with hydrogenated carbonaceous grains.

    PubMed

    Thrower, John D; Friis, Emil E; Skov, Anders L; Jørgensen, Bjarke; Hornekær, Liv

    2014-02-28

    Carbonaceous materials contribute to a significant proportion of the interstellar dust inventory. Reactions on such grain surfaces are thought to play important roles in interstellar chemical networks. Of particular importance are reactions involving hydrogen atoms, and pathways to the formation of the most abundant molecular species, H2. Polycyclic aromatic hydrocarbons (PAHs) are an additional carbon reservoir, accounting for around 10% of the galactic carbon budget. Using thermal desorption and mass spectrometric techniques, we have investigated the interaction between PAH molecules and carbonaceous grain surfaces. We demonstrate that deuterium atoms adsorbed on graphite can react with adsorbed PAH molecules, forming superhydrogenated PAH species. Furthermore, by considering the number of D-atoms remaining bound to the graphite surface and the additional D-atoms in the observed superhydrogenated species, we see evidence for a significant release of deuterium from the graphite surface. We suggest that further reactive processes may be responsible for part of this deuterium loss, indicating that PAHs adsorbed on hydrogenated carbonaceous grains in warm interstellar environments may serve as a route to release H2 as well as forming superhydrogenated PAH species. PMID:24270708

  6. Measuring the primordial deuterium abundance during the cosmic dark ages.

    PubMed

    Sigurdson, Kris; Furlanetto, Steven R

    2006-09-01

    We discuss how measurements of fluctuations in the absorption of cosmic microwave background photons by neutral gas at redshifts z approximately 7-200 could reveal the primordial deuterium abundance of the Universe. The strength of the cross-correlation of brightness-temperature fluctuations in the redshifted 21-cm line of hydrogen with those in the redshifted 92-cm line of deuterium is proportional to the value of the deuterium-to-hydrogen ratio [D/H] fixed during big bang nucleosynthesis. Although challenging, this measurement would provide the cleanest possible determination of [D/H], free from contamination by structure formation processes at lower redshifts. We additionally report our result for the thermal spin-change cross section in deuterium-hydrogen scattering. PMID:17026353

  7. Migration Mechanism for Atomic Hydrogen in Porous Carbon Materials

    SciTech Connect

    Narayanan, B.; Zhao, Y. F.; Ciobanu, C. V.

    2012-05-14

    To explain the fast kinetics of H in porous carbon, we propose that the migration relies on H hopping from a carbon nanotube (CNT) to another. Using density functional theory, we have found that the barrier for H hopping becomes smaller than that for diffusion along a tube for certain CNT separations, decreasting to less than 0.5 eV for separations of -3.1 {angstrom}. Such significant reduction occurs irrespective of radius, chirality, registry, and orientation of the two CNTs: the diffusion is thus facilitated by the porous nature of the material itself. The mechanism proposed is applicable for any porous carbon-based nanomaterials.

  8. Adsorption of Hydrogen Sulfide onto Activated Carbon Fibers: Effect of

    E-print Network

    Borguet, Eric

    . These processes include natural gas processing, petroleum refining, petrochemical plants, Kraft mills, coke ovens is used to control gas streams with high concentrations of hydrogen sulfide. Since it can only recover pollution. Typical tail gas from Claus plant is at 100-315 °C and still contains about 0.8% to 1.5% H2S

  9. Initial hydrogen attack kinetics in a carbon steel

    NASA Astrophysics Data System (ADS)

    McKimpson, Marvin; Shewmon, Paul G.

    1981-05-01

    The kinetics of the initial stages of hydrogen attack in a commercial 0.3 pct C steel (grade A516) were investigated using an in situ dilatometer. The time, temperature and hydrogen pressure dependences of the rate of sample expansion were measured at hydrogen pressures from 1 to 20 MPa, and temperatures from 350 to 475 °C for sample strains of 10-6 to 10-3. Sample expansion began shortly after hydrogen exposure and proceeded at a nearly constant rate throughout the “incubation period” preceding rapid attack. At high temperatures and low pressures, this rate was proportional to PH 2 1.9±0.2 and had an apparent activation energy of 115 ± 9 kJ. At high pressures and low temperatures, the rate was proportional to PPH 2 1.0.62±0.07 and showed an apparent activation energy of 210 ± 13 kJ. This suggests that bubble growth during the incubation period occurs predominantly by grain boundary diffusion and is driven by near-equilibrium internal methane pressures. Sample expansion in the subsequent stages of accelerating growth probably is controlled by creep and methane generation.

  10. From methane to hydrogen, carbon black and water

    Microsoft Academic Search

    L. Fulcheri; Y. Schwob

    1995-01-01

    Most of the total world production of hydrogen comes from vapor cracking of methane. Even though methane is the least carbogen of all hydrocarbons, steam conversion of one ton of methane is accompanied by the emission of about four tons of CO2 into the atmosphere. Simple thermolysis of methane being no more endothermic than the vapor cracking reaction, cracking methane

  11. Mechanism for high hydrogen storage capacity on metal-coated carbon nanotubes: A first principle analysis

    SciTech Connect

    Lu, Jinlian; Xiao, Hong [Department of Physics and Institute for nanophysics and Rare-earth Luminescence, Xiangtan University, Xiangtan, Hunan Province 411105 (China)] [Department of Physics and Institute for nanophysics and Rare-earth Luminescence, Xiangtan University, Xiangtan, Hunan Province 411105 (China); Cao, Juexian, E-mail: jxcao@xtu.edu.cn [Department of Physics and Institute for nanophysics and Rare-earth Luminescence, Xiangtan University, Xiangtan, Hunan Province 411105 (China)] [Department of Physics and Institute for nanophysics and Rare-earth Luminescence, Xiangtan University, Xiangtan, Hunan Province 411105 (China)

    2012-12-15

    The hydrogen adsorption and binding mechanism on metals (Ca, Sc, Ti and V) decorated single walled carbon nanotubes (SWCNTs) are investigated using first principle calculations. Our results show that those metals coated on SWCNTs can uptake over 8 wt% hydrogen molecules with binding energy range -0.2--0.6 eV, promising potential high density hydrogen storage material. The binding mechanism is originated from the electrostatic Coulomb attraction, which is induced by the electric field due to the charge transfer from metal 4s to 3d. Moreover, we found that the interaction between the H{sub 2}-H{sub 2} further lowers the binding energy. - Graphical abstract: Five hydrogen molecules bound to individual Ca decorated (8, 0) SWCNT : a potential hydrogen-storage material. Highlights: Black-Right-Pointing-Pointer Each transition metal atom can adsorb more than four hydrogen molecules. Black-Right-Pointing-Pointer The interation between metal and hydrogen molecule is electrostatic coulomb attraction. Black-Right-Pointing-Pointer The electric field is induced by the charge transfer from metal 4s to metal 3d. Black-Right-Pointing-Pointer The adsorbed hydrogen molecules which form supermolecule can further lower the binding energy.

  12. Analysis of diffential absorption lidar technique for measurements of anhydrous hydrogen chloride from solid rocket motors using a deuterium fluoride laser

    NASA Technical Reports Server (NTRS)

    Bair, C. H.; Allario, F.

    1977-01-01

    An active optical technique (differential absorption lidar (DIAL)) for detecting, ranging, and quantifying the concentration of anhydrous HCl contained in the ground cloud emitted by solid rocket motors (SRM) is evaluated. Results are presented of an experiment in which absorption coefficients of HCl were measured for several deuterium fluoride (DF) laser transitions demonstrating for the first time that a close overlap exists between the 2-1 P(3) vibrational transition of the DF laser and the 1-0 P(6) absorption line of HCl, with an absorption coefficient of 5.64 (atm-cm) to the -1 power. These measurements show that the DF laser can be an appropriate radiation source for detecting HCl in a DIAL technique. Development of a mathematical computer model to predict the sensitivity of DIAL for detecting anhydrous HCl in the ground cloud is outlined, and results that assume a commercially available DF laser as the radiation source are presented.

  13. Stable Isotope (delta OXYGEN-18, Delta Deuterium, Delta CARBON-13) Dendroclimatological Studies in the Waterloo Region of Southern Ontario, Canada, Between AD 1610 and 1990.

    NASA Astrophysics Data System (ADS)

    Buhay, William Mark

    Oxygen (delta^{18} O), hydrogen (delta^2H) and carbon (delta^{13}C) isotopes were measured in wood cellulose from elm, white pine and maple trees that grew in southwestern Ontario, Canada. The measured oxygen and hydrogen isotopic data were used for model-based reconstructions of delta^{18}{O}_{meteoric water}, mean annual temperature (MAT) and relative humidity for a period, AD 1610 to 1880, that precedes instrumental records of climate. The carbon isotope measurements were compared with the Cellulose Model inferred climate data to reveal additional environmental information. Modifications made to the Cellulose Model focused on the dynamics of oxygen and hydrogen isotopic fractionation in plants during evapotranspiration and photosynthetic assimilation. For instance, kinetic fractionation of ^{18}O was found to be predictable from theoretical considerations of leaf energy balance and boundary layer dynamics. Kinetic fractionation during evapotranspiration is sensitive to the nature of the boundary layer, which is controlled by leaf size and morphology. Generally, plants with small segmented leaves have a lower component of turbidity in the leaf boundary layer, which results in higher kinetic fractionation values, than do plants having large simple leaves and more turbulent boundary layers. Kinetic ^2H enrichment in plant leaf water can also be rationalized in terms of leaf size and morphology when an apparent temperature-dependent isotope effect, acting in opposition to evaporative enrichment, is taken into account. Accounting for this temperature -dependent isotope effect helps to: (1) reconcile hydrogen kinetic fractionation inconsistencies for different leaves; (2) explain a temperature effect previously attributed to variable biochemical fractionation during cellulose synthesis, and; (3) verify hydrogen biochemical effects in plants. This improved characterization of the oxygen and hydrogen isotopic effects in plants, using the modified Cellulose Model, helped to constrain the paleoclimate interpretations from three species of trees that grew in different hydrologic settings. The inferred climate data, integrated with the hydrological setting of the trees and various climate modifying factors in the Great Lakes basin, generated an independent interpretation of summer and winter conditions in southwestern Ontario for the past 380 years. The inferred evidence indicates that conditions in southwestern Ontario between 1610 and 1750 typified those of "Little Ice Age" Europe by being cooler and drier than present. This probably resulted from a southerly positioning of the Polar Front, with respect to southwestern Ontario, which allowed sub-polar airmasses to dominantly influence this region. A subsequent retreat of the Polar Front north after 1750 allowed for a predominance of sub -tropical airmasses that resulted in warm-moist conditions and an increase in winter precipitation in this area between 1750 and 1850. Another advance of the Polar Front position south, sometime after 1850, renewed cool-dry conditions and reduced winter precipitation amounts in southwestern Ontario until the early twentieth century, after which time, climate ameliorated progressively. Typical of the findings in previous studies, a significant correlation between climate parameters and delta^{13}C_ {cellulose} values is observed for a tree (maple) from a groundwater recharge setting. The correlation is best between MAT and delta^ {13}C_{cellulose} values between 1610 and 1850. The breakdown of this correlation after 1850, due to enriched delta ^{13}C_{cellulose} values, could indicate that the tree is responding to an alteration in soil chemistry occurring due to the fallout of anthropogenically produced atmospheric pollutants. This is because the effects of depleted soil nutrients and/or leached phytotoxins on delta^ {13}C_{cellulose} values in wood cellulose, are similar to ones seen in trees that regularly experience drought stress.

  14. The Role of Hydrogen in Small Amorphous Carbon Grains: The IR Spectrum

    NASA Technical Reports Server (NTRS)

    Mennella, V.; Colangeli, L.; Pestellini, C. Cecchi; Palomba, E.; Palumbo, P.; Rotundi, A.; Bussoletti, E.

    1996-01-01

    Preliminary results on the evolution of the IR spectrum of hydrogenated carbon grains as a function of heat treatment are presented. The transformation of C-H and C-C bonding configurations is considered and the correlation with other properties of grains, such as their microstructure, is analyzed.

  15. Tropospheric carbon monoxide and hydrogen measurements over Kalimantan in Indonesia and northern Australia during October, 1997

    Microsoft Academic Search

    Yousuke Sawa; Hidekazu Matsueda; Yukitomo Tsutsumi; Jørgen B. Jensen; Hisayuki Y. Inoue; Yukio Makino

    1999-01-01

    During the PACE-5 campaign over Australia and Indonesia in October 1997, we used an aircraft to measure carbon monoxide (CO) and hydrogen (H2). Latitudinal distributions of CO and H2 clearly showed a large increase from northern Australia to Kalimantan in Indonesia. Elevated CO levels over northern Australia were observed only in the smoke plumes of savanna fires. A thick smoke

  16. Improved wear performance of ultra high molecular weight polyethylene coated with hydrogenated diamond like carbon

    Microsoft Academic Search

    J. A. Puértolas; V. Martínez-Nogués; M. J. Martínez-Morlanes; M. D. Mariscal; F. J. Medel; C. López-Santos; F. Yubero

    2010-01-01

    Hydrogenated diamond like carbon (DLCH) thin films were deposited on medical grade ultra high molecular weight polyethylene (UHMWPE) by radio frequency plasma enhanced chemical vapor deposition. The DLCH coating thicknesses ranged from 250 to 700nm. The substrates were disks made of UHMWPEs typically used for soft components in artificial joints, namely virgin GUR 1050 and highly crosslinked (gamma irradiated in

  17. Evaluation of hydrogenated physically small carbon electrodes in resisting fouling during voltammetric detection of dopamine

    Microsoft Academic Search

    Subbiah Alwarappan; K. Scott A. Butcher; Danny K. Y. Wong

    2007-01-01

    In this work, a hydrogenated film deposited on physically small carbon cylinder electrodes was used to minimise electrode fouling that is commonly encountered during electrochemical detection of the neurotransmitter dopamine in vivo. Electrode fouling generally arises from the inhibition of electron transfer reactions on an electrode surface covered by hydrophilic surface active agents including proteins, peptides and lipids present in

  18. Hydrogen and electricity from coal with carbon dioxide separation using chemical looping reactors

    Microsoft Academic Search

    Xiang Wenguo; Chen Yingying

    2007-01-01

    Concern about global climate change has led to research on low COâ emission in the process of the energy conversion of fossil fuel. One of the solutions is the conversion of fossil fuel into carbon-free energy carriers, hydrogen, and electricity with COâ capture and storage. In this paper, the main purpose is to investigate the thermodynamics performance of converting coal

  19. Three-dimensional macroscopic assemblies of low-dimensional carbon nitrides for enhanced hydrogen evolution.

    PubMed

    Jun, Young-Si; Park, Jihee; Lee, Sun Uk; Thomas, Arne; Hong, Won Hi; Stucky, Galen D

    2013-10-11

    Simple organic cooperative assembly of triazine molecules leads to three-dimensional macroscopic assemblies of low-dimensional graphitic carbon nitrides (g-CNs), for example, nanoparticles, nanotubes, and nanosheets. The approach enables the characterization of the cooperative properties and photocatalytic activities of low-dimensional g-CN materials in hydrogen evolution reactions from water under visible light. PMID:24038778

  20. Mass fractionation of carbon and hydrogen secondary ions upon Cs+ bombardment of organic materials

    E-print Network

    materials are primarily composed of carbon and hydrogen, and because isotopic labeling is often utilized samples.8,9 Therefore, isotopic labeling is often employed to more accurately characterize organic materials.10,11 Isotopic labeling has also been shown to greatly minimize matrix effects12,13 that occur

  1. Using steam reforming to produce hydrogen with carbon dioxide capture by chemical-looping combustion

    Microsoft Academic Search

    Magnus Rydén; Anders Lyngfelt

    2006-01-01

    In this paper, a novel process for hydrogen production by steam reforming of natural gas with inherent capture of carbon dioxide by chemical-looping combustion is proposed. The process resembles a conventional circulating fluidized bed combustor with reforming taking place in reactor tubes located inside a bubbling fluidized bed. Energy for the endothermic reforming reactions is provided by indirect combustion that

  2. SPITZER OBSERVATIONS OF SHOCK-EXCITED HYDROGEN DEUTERIDE IN IC 443C, HH 7, AND HH 54: PROBING THE GAS-PHASE DEUTERIUM ABUNDANCE IN THE DENSE INTERSTELLAR MEDIUM

    SciTech Connect

    Yuan Yuan; Neufeld, David A. [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Sonnentrucker, Paule [Space Telescope Science Institute, 3700 San Martin Dr, Baltimore, MD 21218 (United States); Melnick, Gary J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Watson, Dan M. [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627 (United States)

    2012-07-10

    We present and analyze observations-carried out using the Infrared Spectrograph (IRS) on the Spitzer Space Telescope-of the R(3) and R(4) pure rotational lines of hydrogen deuteride (HD) detected from shock-heated material associated with the supernova remnant IC 443C and with the Herbig-Haro objects HH 7 and HH 54. Assuming a continuous temperature distribution for gas observed along the sight lines, we have constrained the gas density to be in the {approx}10{sup 3}-10{sup 4} cm{sup -3} range, using both spectroscopic data for H{sub 2}, HD, and CO from IRS and from the Infrared Space Observatory (ISO), as well as photometric data from Spitzer's Infrared Array Camera. The derived HD abundance relative to H{sub 2} is quite sensitive to the assumed excitation conditions in the emitting gas. Assuming that HD accounts for all gas-phase deuterium in the emitting material, and using all the available spectroscopic data to constrain the excitation conditions, we obtained gas-phase deuterium abundances [D/H]{sub gas} of 0.95{sup +0.54}{sub -0.27} Multiplication-Sign 10{sup -5} and 0.87{sup +0.31}{sub -0.27} Multiplication-Sign 10{sup -5} (statistical errors only) for IC 443C and HH 54, respectively. The uncertainties in the HD abundance are dominated by systematic effects related to the poorly known excitation conditions, and more accurate estimates of the HD abundance in shocked molecular clouds will require measurements of the emission in additional HD rotational transitions.

  3. Hydrogenated amorphous carbon (a:C-H) in the planetary nebula NGC 7027

    NASA Technical Reports Server (NTRS)

    Goebel, John H.

    1987-01-01

    A spectroscopic identification of the infrared continuum radiation is proposed for the planetary nebula NGC 7027. Hydrogenated amorphous carbon (a:C-H) is shown to account for the undulating spectrum between 5 and 15 microns. The unidentified infrared emission bands lie at the peaks in the a:C-H spectrum, pointing to their association with a carbon polymorph, possibly a:C-H or polycyclic aromatic hydrocarbon molecules. Except for atomic emission lines, all the infrared emission from NGC 7027 comes from one or another polymorph of carbon.

  4. Plasma deposition of amorphous hydrogenated carbon films on III-V semiconductors

    NASA Technical Reports Server (NTRS)

    Pouch, John J.; Warner, Joseph D.; Liu, David C.; Alterovitz, Samuel A.

    1988-01-01

    Amorphous hydrogenated carbon films were grown on GaAs, InP and fused silica substrates using plasmas generated from hydrocarbon gases. Methane and n-butane sources were utilized. The effects of flow rate and power density on film growth were investigated. Carbon was the major constituent in the films. The degree of asymmetry at the carbon-semiconductor interface was approximately independent of the power density. Different H-C bonding configurations were detected by the technique of secondary-ion mass spectrometry. Band gaps up to 3 eV were obtained from optical absorption studies. Breakdown strengths as high as 600 MV/m were measured.

  5. Hydrogen Storage in Novel Carbon-Based Nanostructured Materials

    SciTech Connect

    Whitney, E. S.; Curtis, C. J.; Engtrakul, C.; Davis, M. F.; Su, T.; Parilla, P. A.; Simpson, L. J.; Blackburn, J. L.; Zhao, Y.; Kim, Y.-H.; Zhang, S. B.; Heben, M. J.; Dillon, A. C.

    2006-01-01

    Experimental wet chemical approaches to complex an iron atom with two C60 fullerenes, representing a new molecule, dubbed a 'bucky dumbbell', have been demonstrated. The structure of this molecule has been determined by 13C solid-state nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR). Furthermore, this structure has been shown to have unique binding sites for dihydrogen molecules with the technique of temperature programmed desorption (TPD). The new adsorption sites have binding energies that are stronger than that observed for hydrogen physisorbed on planar graphite, but significantly weaker than a chemical C-H bond. Further development of these molecules could make them ideal candidates for onboard vehicular hydrogen storage.

  6. Hydrogen production from coal by separating carbon dioxide during gasification

    Microsoft Academic Search

    Shiying Lin; Michiaki Harada; Yoshizo Suzuki; Hiroyuki Hatano

    2002-01-01

    Hydrogen generation during the reaction of a coal\\/CaO mixture with high pressure steam was investigated using a flow-type reactor. Coal, CaO and CO reactions with steam, and CO2 absorption by Ca(OH)2 or CaO occurred simultaneously in the experiment. It was found that H2 was the primary resultant gas, comprising about 85% of the reaction products. CO2 was fixed into CaCO3

  7. Fractionation of carbon and hydrogen isotopes by methane-oxidizing bacteria

    USGS Publications Warehouse

    Coleman, D.D.; Risatti, J.B.; Schoell, M.

    1981-01-01

    Carbon isotopic analysis of methane has become a popular technique in the exploration for oil and gas because it can be used to differentiate between thermogenic and microbial gas and can sometimes be used for gas-source rock correlations. Methane-oxidizing bacteria, however, can significantly change the carbon isotopic composition of methane; the origin of gas that has been partially oxidized by these bacteria could therefore be misinterpreted. We cultured methane-oxidizing bacteria at two different temperatures and monitored the carbon and hydrogen isotopic compositions of the residual methane. The residual methane was enriched in both 13C and D. For both isotopic species, the enrichment at equivalent levels of conversion was greater at 26??C than at 11.5??C. The change in ??D relative to the change in ??13C was independent of temperature within the range studied. One culture exhibited a change in the fractionation pattern for carbon (but not for hydrogen) midway through the experiment, suggesting that bacterial oxidation of methane may occur via more than one pathway. The change in the ??D value for the residual methane was from 8 to 14 times greater than the change in the ??13C value, indicating that combined carbon and hydrogen isotopic analysis may be an effective way of identifying methane which has been subjected to partial oxidation by bacteria. ?? 1981.

  8. Effects of heavy ion irradiation on amorphous hydrogenated (diamondlike) carbon films

    SciTech Connect

    Prawer, S.; Kalish, R.; Adel, M.; Richter, V.

    1987-05-01

    Energetic ion-beam irradiation of diamondlike carbon thin films induces a decrease of 5--6 orders of magnitude in the resistivity of the films from their as-grown value of 10/sup 7/ ..cap omega.. cm. Diagnostics used to characterize the nature of the transformation included optical absorption measurements (band gap), Raman spectroscopy (microcrystalline structure), Rutherford backscattering spectroscopy (hydrogen content of the films), and measurements of the temperature dependence of the conductivity (electronic structure). It was found that the initial decrease in resistivity with an increasing ion dose is due to the loss of hydrogen from the films, with a concomitant decrease in the optical band gap. Heating the films during the irradiation greatly accelerates the rate of hydrogen loss as a function of dose. Once the hydrogen removal is complete, further irradiation increases the film conductivity by inducing the growth of microcrystallites of graphite.

  9. Record Hydrogen Storage Capacities in Advanced Carbon Storage Materials

    NASA Astrophysics Data System (ADS)

    Wexler, C.; Beckner, M.; Romanos, J.; Burress, J.; Kraus, M.; Olsen, R.; Dohnke, E.; Carter, S.; Casteel, G.; Kuchta, B.; Firlej, L.; Leimkuehler, E.; Tekeei, A.; Suppes, G.; Pfeifer, P.

    2010-03-01

    Carbons can be engineered to achieve exceptional storage capacities: the ALL-CRAFT (www.all-craft.missouri.edu) nanoporous carbon achieves gravimetric excess adsorption of 0.073 kg H2/kg C, gravimetric storage capacity of 0.106 kg H2/kg C, and volumetric storage capacity of 0.040 kg H2/l C (80 K, 100 bar). The nanopores generate high storage capacity by having: high surface area (2,600 m^2/g); high H2-wall interaction; and multi-layer H2 adsorption (cryogenic). We we show how the experimental characteristics of the ALL-CRAFT carbon correlate to the observed H2 storage, with help from theoretical considerations and GCMC simulations. The ALL-CRAFT carbon is composed of a large variety of pore sizes which generates substantial heterogeneity. We explain most features observed by considering superpositions of low- and high-binding energy sites (9 kJ and 5 kJ/mol), corresponding to wide and narrow (< 1 nm) pores. We further explain: exceptional low-temperature storage (in excess of the usual Chahine's rule); and absence of an excess adsorption peak (for 0 < P < 100 bar).

  10. Fragmentation cross sections on hydrogen and carbon for propagation calculations

    Microsoft Academic Search

    J. Isbert; T. G. Guzik; M. Hollier

    1993-01-01

    Over the past several years measurements have been made of the fragmentation of Silicon and Oxygen at energies less than 360 MeV\\/nucleon on Carbon and polyethylene targets. The apparatus to identify fragment isotopes consisted of a stack of 36 solid detectors, beam geometry and characterization versus laboratory production angle was measured by moving the apparatus relative to the beam direction.

  11. Electron transport properties of a single-walled carbon nanotube in the presence of hydrogen cyanide: first-principles analysis.

    PubMed

    Srivastava, Anurag; Sharma, Vikash; Kaur, Kamalpreet; Khan, Md Shahzad; Ahuja, Rajeev; Rao, V K

    2015-07-01

    First-principles analysis based on density functional theory was performed to compute the electronic and transport properties of a single-walled carbon nanotube in the presence of hydrogen cyanide. A chiral (4,1) carbon nanotube was found to become less metallic as the number of hydrogen cyanide molecules nearby increased. When there were a sufficient number of hydrogen cyanide molecules close to the nanotube, it became semiconducting. This metallic to semiconducting transformation of the nanotube was verified by analyzing its conductance and current as a function of the number of molecules of hydrogen cyanide present. The conductivity of the carbon nanotube was very high when no hydrogen cyanide molecules were present, but decreased considerably when even just a single hydrogen cyanide molecule approached the surface of the nanotube. Graphical Abstract SWCNT based HCN sensor and its Current vs Bias voltage characteristics. PMID:26072123

  12. Spatial Variability in the Ratio of Interstellar Atomic Deuterium to Hydrogen. II. Observations toward ?2 Velorum and ? Puppis by the Interstellar Medium Absorption Profile Spectrograph

    NASA Astrophysics Data System (ADS)

    Sonneborn, George; Tripp, Todd M.; Ferlet, Roger; Jenkins, Edward B.; Sofia, U. J.; Vidal-Madjar, Alfred; Wo?niak, Prezemys?aw R.

    2000-12-01

    High-resolution far-ultraviolet spectra of the early-type stars ?2 Vel and ? Pup were obtained to measure the interstellar deuterium abundances in these directions. The observations were made with the Interstellar Medium Absorption Profile Spectrograph (IMAPS) during the ORFEUS-SPAS II mission in 1996. IMAPS spectra cover the wavelength range 930-1150 Å with ?/??~80,000. The interstellar D I features are resolved and cleanly separated from interstellar H I in the Ly? and Ly? profiles of both sight lines and also in the Ly? profile of ? Pup. The D I profiles were modeled using a velocity template derived from several N I lines in the IMAPS spectra recorded at higher signal-to-noise ratio. To find the best D I column density, we minimized ?2 for model D I profiles that included not only the N(D I) as a free parameter, but also the effects of several potential sources of systematic error, which were allowed to vary as free parameters. H I column densities were measured by analyzing Ly? absorption profiles in a large number of IUE high-dispersion spectra for each of these stars and applying this same ?2-minimization technique. Ultimately we found that D/H=2.18+0.36-0.31×10-5 for ?2 Vel and 1.42+0.25-0.23×10-5 for ? Pup, values that contrast markedly with D/H derived in Paper I for ? Ori A (the stated errors are 90% confidence limits). Evidently, the atomic D/H ratio in the ISM, averaged over path lengths of 250-500 pc, exhibits significant spatial variability. Furthermore, the observed spatial variations in D/H do not appear to be anticorrelated with N/H, one measure of heavy-element abundances. We briefly discuss some hypotheses to explain the D/H spatial variability. Within the framework of standard big bang nucleosynthesis, the large value of D/H found toward ?2 Vel is equivalent to a cosmic baryon density of ?Bh2=0.023+/-0.002, which we regard as an upper limit since there is no correction for the destruction of deuterium in stars. This paper is dedicated in memory of Judith L. Tokel, wife of the first author, who passed away on 2000 June 10. Her enthusiastic support and encouragement were essential to its successful completion.

  13. The role of destabilization of palladium hydride on the hydrogen uptake of Pd-containing activated carbons

    SciTech Connect

    Bhat, Vinay V [ORNL; Contescu, Cristian I [ORNL; Gallego, Nidia C [ORNL

    2009-01-01

    This paper reports on differences in stability of Pd hydride phases in palladium particles with various degrees of contact with microporous carbon supports. A sample containing Pd embedded in activated carbon fiber (Pd-ACF; 2 wt% Pd) was compared with commercial Pd nanoparticles deposited on microporous activated carbon (Pd-catalyst, 3 wt% Pd) and with support-free nanocrystalline palladium (Pd-black). The morphology of materials was characterized by electron microscopy, and the phase transformations were analyzed over a large range of hydrogen partial pressures (0.003 - 10 bar) and at several temperatures using in-situ X-ray diffraction. The results were verified with volumetric hydrogen uptake measurements. Results indicate that higher degree of Pd-carbon contacts for Pd particles embedded in a microporous carbon matrix induce efficient pumping of hydrogen out of -PdHx. It was also found that thermal cleaning of carbon surface groups prior to exposure to hydrogen further enhances the hydrogen pumping power of the microporous carbon support. In brief, this study highlights that the stability of -PdHx phase supported on carbon depends on the degree of contact between Pd-carbon and the nature of the carbon surface.

  14. "TOF2H": A precision toolbox for rapid, high density/high coverage hydrogen-deuterium exchange mass spectrometry via an LC-MALDI approach, covering the data pipeline from spectral acquisition to HDX rate analysis

    PubMed Central

    Nikamanon, Pornpat; Pun, Elroy; Chou, Wayne; Koter, Marek D; Gershon, Paul D

    2008-01-01

    Background Protein-amide proton hydrogen-deuterium exchange (HDX) is used to investigate protein conformation, conformational changes and surface binding sites for other molecules. To our knowledge, software tools to automate data processing and analysis from sample fractionating (LC-MALDI) mass-spectrometry-based HDX workflows are not publicly available. Results An integrated data pipeline (Solvent Explorer/TOF2H) has been developed for the processing of LC-MALDI-derived HDX data. Based on an experiment-wide template, and taking an ab initio approach to chromatographic and spectral peak finding, initial data processing is based on accurate mass-matching to fully deisotoped peaklists accommodating, in MS/MS-confirmed peptide library searches, ambiguous mass-hits to non-target proteins. Isotope-shift re-interrogation of library search results allows quick assessment of the extent of deuteration from peaklist data alone. During raw spectrum editing, each spectral segment is validated in real time, consistent with the manageable spectral numbers resulting from LC-MALDI experiments. A semi-automated spectral-segment editor includes a semi-automated or automated assessment of the quality of all spectral segments as they are pooled across an XIC peak for summing, centroid mass determination, building of rates plots on-the-fly, and automated back exchange correction. The resulting deuterium uptake rates plots from various experiments can be averaged, subtracted, re-scaled, error-barred, and/or scatter-plotted from individual spectral segment centroids, compared to solvent exposure and hydrogen bonding predictions and receive a color suggestion for 3D visualization. This software lends itself to a "divorced" HDX approach in which MS/MS-confirmed peptide libraries are built via nano or standard ESI without source modification, and HDX is performed via LC-MALDI using a standard MALDI-TOF. The complete TOF2H package includes additional (eg LC analysis) modules. Conclusion "TOF2H" provides a comprehensive HDX data analysis package that has accelerated the processing of LC-MALDI-based HDX data in the authors' lab from weeks to hours. It runs in a standard MS Windows (XP or Vista) environment, and can be downloaded or obtained from the authors at no cost. PMID:18803853

  15. Analysis of hydrogen sorption characteristics of boron-doped activated carbons

    NASA Astrophysics Data System (ADS)

    Beckner, M.; Romanos, J.; Stalla, D.; Dohnke, E.; Singh, A.; Lee, M.; Suppes, G.; Hawthorne, M. F.; Yu, P.; Wexler, C.; Pfeifer, P.

    2011-03-01

    There is significant interest in the properties of boron-doped activated carbons for their potential to improve hydrogen storage. Boron-doped activated carbons have been produced using a novel process involving the pyrolysis of a boron containing compound and subsequent high-temperature annealing. In this talk we will present a systematic study of the effect of different boron doping processes on the samples' surface area, micropore structure, and hydrogen sorption. Experimental results include boron content from prompt gamma neutron activation analysis, boron-carbon chemistry from Fourier transform infrared spectroscopy (FTIR), nitrogen subcritical adsorption, and 80K and 90K hydrogen adsorption isotherms which allow us to evaluate the hydrogen binding energy for each sorptive material. This material is based on work supported by the US Department of Defense under Awards No. N00164-07-P-1306 and N00164-08-C-GS37, the US Department of Energy under Awards No. DE-FG02-07ER46411 and DE-FG36-08GO18142.

  16. Synthesis of zeolite-casted microporous carbons and their hydrogen storage capacity.

    PubMed

    Lee, Seul-Yi; Park, Soo-Jin

    2012-10-15

    Zeolite-casted microporous carbons (ZMiPCs) were synthesized using the replica casting method. The ZMiPC were also treated chemically by H(3)PO(4) (A-ZMiPC) or KOH (B-ZMiPC) impregnation, to investigate the effect of the acceptor-donor interaction on the hydrogen storage behaviors. The presence of functional groups of the modified ZMiPC surfaces was confirmed by X-ray photoelectron spectroscopy. The total acidity of the carbon surfaces was determined using the Boehm titration method. The microstructure was characterized by X-ray diffraction. The N(2)/77K adsorption/desorption isotherms were analyzed to characterize specific surface area, pore volume, and pore size distribution of the samples. The capacity of hydrogen adsorption was evaluated using a pressure-composition-temperature apparatus at 298 K/100 bar. From these results, the specific surface areas and micropore volume of ZMiPC increased more than two fold compared to the zeolite template. Meanwhile, the textural properties of A-ZMiPC and B-ZMiPC were decreased by the chemical treatments. Consequently, the largest hydrogen storage was obtained on A-ZMiPC, even though their textural properties had decreased, due to a charge induced dipole interaction between the modified carbon surface and hydrogen molecules. PMID:22809550

  17. ENHANCED HYDROGEN ECONOMICS VIA COPRODUCTION OF FUELS AND CARBON PRODUCTS

    SciTech Connect

    Kennel, Elliot B; Bhagavatula, Abhijit; Dadyburjor, Dady; Dixit, Santhoshi; Garlapalli, Ravinder; Magean, Liviu; Mukkha, Mayuri; Olajide, Olufemi A; Stiller, Alfred H; Yurchick, Christopher L

    2011-03-31

    This Department of Energy National Energy Technology Laboratory sponsored research effort to develop environmentally cleaner projects as a spin-off of the FutureGen project, which seeks to reduce or eliminate emissions from plants that utilize coal for power or hydrogen production. New clean coal conversion processes were designed and tested for coproducing clean pitches and cokes used in the metals industry as well as a heavy crude oil. These new processes were based on direct liquefaction and pyrolysis techniques that liberate volatile liquids from coal without the need for high pressure or on-site gaseous hydrogen. As a result of the research, a commercial scale plant for the production of synthetic foundry coke has broken ground near Wise, Virginia under the auspices of Carbonite Inc. This plant will produce foundry coke by pyrolyzing a blend of steam coal feedstocks. A second plant is planned by Quantex Energy Inc (in Texas) which will use solvent extraction to coproduce a coke residue as well as crude oil. A third plant is being actively considered for Kingsport, Tennessee, pending a favorable resolution of regulatory issues.

  18. Hydrogen and oxygen trapping and retention in stainless steel and graphite materials irradiated in plasma

    NASA Astrophysics Data System (ADS)

    Begrambekov, L.; Ayrapetov, A.; Ermakov, V.; Kaplevsky, A.; Sadovsky, Ya.; Shigin, P.

    2013-11-01

    The paper presents the results of experimental investigation of energy and flux dependences of hydrogen isotopes and oxygen trapping in carbon materials (carbon fiber composite and pyrolitic graphite), and metals (stainless steel and nickel) under irradiation in the deuterium gas discharge plasma with and without oxygen addition. The dependence of hydrogen trapping on ion energy, ion current density, oxygen addition in deuterium plasma are presented and analyzed. The sorbed molecules, containing hydrogen atoms from the residual gas and deuterium atoms of the working gas are shown to be the important source of hydrogen trapping in both carbon based materials and stainless steel. Irradiation of the SS vacuum vessel with the neutrals or/and ions of (D2 + O2) plasma initiate the hydrogen diffusion from the vessel wall and H2, HD, D2O, HDO, H2O molecule formation on the wall surface. Trapping of the low energy plasma particles and the particles from the sorbed molecules as well as modification of working gas composition are considered as the processes provided at the expense of the potential energy of plasma particles with respect to the surface and occurred through their inelastic collisions with the surface. The hydrogen trapping occurred due to “potential” processes was named as “potential”, and in contrast the trapping of fast particles due to their kinetic energy was labeled as “kinetic”.

  19. Toward New Candidates for Hydrogen Storage: High Surface Area Carbon Aerogels

    SciTech Connect

    Kabbour, H; Baumann, T F; Satcher, J H; Saulnier, A; Ahn, C C

    2007-02-05

    We report the hydrogen surface excess sorption saturation value of 5.3 wt% at 30 bar pressure at 77 K, from an activated carbon aerogel with a surface area of 3200 m{sup 2}/g as measured by Brunauer-Emmett-Teller (BET) analysis. This sorption value is one of the highest we have measured in a material of this type, comparable to values obtained in high surface area activated carbons. We also report, for the first time, the surface area dependence of hydrogen surface excess sorption isotherms of carbon aerogels at 77 K. Activated carbon aerogels with surface areas ranging from 1460 to 3200 m{sup 2}/g are evaluated and we find a linear dependence of the saturation of the gravimetric density with BET surface area for carbon aerogels up to 2550 m{sup 2}/g, in agreement with data from other types of carbons reported in the literature. Our measurements show these materials to have a differential enthalpy of adsorption at zero coverage of {approx}5 to 7 kJ/mole. We also show that the introduction of metal nanoparticles of nickel improves the sorption capacity while cobalt additions have no effect.

  20. Carbon and hydrogen isotope effects during sorption of organic contaminants on carbonaceous materials.

    PubMed

    Schüth, Christoph; Taubald, Heinrich; Bolaño, Nerea; Maciejczyk, Kirsten

    2003-07-01

    Stable carbon and hydrogen isotopes can be an efficient means to validate biodegradation of organic contaminants in groundwater since it results in an isotopic fractionation. A prerequisite in applying this method in the field is the proof that other processes decreasing the contaminant concentration are conservative with respect to isotope effects. In this paper we show for carbon isotopes of halogenated hydrocarbon compounds [trichloroethene (TCE), cis-dichloroethene (c-DCE), vinylchloride (VC)] and carbon and hydrogen isotopes of BTEX compounds (benzene, toluene, p-xylene) that no significant fractionation occurs during equilibrium sorption onto activated carbon, lignite coke and lignite. In general, effects were in the range of the reproducibility limit of the analytical instrument (0.5 per thousand for delta13C, and 8 per thousand for delta2H). This observation was made for fractions sorbed of less than 5% to more than 95%. Also for rate-limited sorption of TCE onto activated carbon, no significant fractionation in carbon isotopes could be observed. These findings support the assumption that for these classes of compounds, sorption processes in aquifer systems are conservative with respect to isotope effects. PMID:12814884

  1. Polygeneration of SNG, hydrogen, power, and carbon dioxide from Texas lignite

    SciTech Connect

    Gray, D.; Salerno, S.; Tomlinson, G.; Marano, J.J. [Mitretek Systems, Falls Church, VA (United States)

    2004-12-15

    This feasibility study has shown that siting a mine mouth lignite fed gasification plant in Texas to produce hydrogen, SNG, electric power, and carbon dioxide could be economically feasible in an era of high natural gas prices. Because of the high moisture content of the lignite the choice of gasification system becomes an important issue. Hydrogen produced from Texas lignite in a coproduction plant could be produced in the range $5.20-$6.20/MMBTU (HHV basis) equivalent to between $0.70 and $0.84 per kilogram. This range of hydrogen costs is equivalent to hydrogen produced by steam methane reforming of natural gas if the natural gas feed price was between $3.00 and $4.00/MMBTU. With natural gas prices continuing to remain above $5.00/MMBTU this concept of using Texas lignite for hydrogen production would be economically viable. For the production of SNG from Texas lignite, the costs range from $6.90-$5.00/MMBTU (HHV basis). If natural gas prices remain above $5.00/MMBTU then the configuration using the advanced dry feed gasification system would be economically viable for production of SNG. This option may be even more attractive with other low rank coals such as Wyoming subbituminous and North Dakota lignite coals that are priced lower than Texas lignite. Production of electric power from these conceptual coproduction plants provides a valuable revenue stream. The opportunity to sell carbon dioxide for EOR in Texas provided another valuable revenue stream for the plants. The break even cost of recovering the carbon dioxide ranged from about $5.50 to $7.75 per ton depending on whether SNG or hydrogen was the product.

  2. Hydrogen

    NSDL National Science Digital Library

    Iowa Public Television. Explore More Project

    2004-01-01

    This article explores the possibilities of using hydrogen as a renewable energy source, pointing out that hydrogen fuel and hydrogen fuel cells are two options for generating power from hydrogen. The article gives an overview of the three methods used to isolate hydrogen for energy-production purposes: steam reforming, electrolysis, and burning. Information is also offered about the uses, limitations, and benefits of hydrogen as an energy source. Supporting web links are provided, including links to an article about fuel cell buses and to animations that demonstrate how hydrogen fuel cells operate.

  3. Structure and Reactions of Carbon and Hydrogen on Ru(0001): A Scanning Tunneling Microscopy Study

    SciTech Connect

    Shimizu, Tomoko K.; Mugarza, Aitor; Cerda, Jorge; Salmeron, Miquel

    2008-09-09

    The interaction between carbon and hydrogen atoms on a Ru(0001) surface was studied using scanning tunneling microscopy (STM), Density Functional Theory (DFT) and STM image calculations. Formation of CH species by reaction between adsorbed H and C was observed to occur readily at 100 K. When the coverage of H increased new complexes of the form CH+nH (n = 1, 2 and 3) were observed. These complexes, never observed before, might be precursors for further hydrogenation reactions. DFT analysis reveals that a considerable energy barrier exists for the CH+H {yields} CH{sub 2} reaction.

  4. Multi-Walled Carbon Nanotube-Doped Tungsten Oxide Thin Films for Hydrogen Gas Sensing

    PubMed Central

    Wongchoosuk, Chatchawal; Wisitsoraat, Anurat; Phokharatkul, Ditsayut; Tuantranont, Adisorn; Kerdcharoen, Teerakiat

    2010-01-01

    In this work we have fabricated hydrogen gas sensors based on undoped and 1 wt% multi-walled carbon nanotube (MWCNT)-doped tungsten oxide (WO3) thin films by means of the powder mixing and electron beam (E-beam) evaporation technique. Hydrogen sensing properties of the thin films have been investigated at different operating temperatures and gas concentrations ranging from 100 ppm to 50,000 ppm. The results indicate that the MWCNT-doped WO3 thin film exhibits high sensitivity and selectivity to hydrogen. Thus, MWCNT doping based on E-beam co-evaporation was shown to be an effective means of preparing hydrogen gas sensors with enhanced sensing and reduced operating temperatures. Creation of nanochannels and formation of p-n heterojunctions were proposed as the sensing mechanism underlying the enhanced hydrogen sensitivity of this hybridized gas sensor. To our best knowledge, this is the first report on a MWCNT-doped WO3 hydrogen sensor prepared by the E-beam method. PMID:22163623

  5. Hydrogen Adsorption in Purified Single Walled Carbon Nanotubes (SWNTs)

    NASA Astrophysics Data System (ADS)

    Pradhan, B. K.; Harutyunyan, A. R.; Sumanasekera, G. U.; Eklund, P. C.; Tokune, T.; Fujiwara, Y.

    2001-03-01

    We report results of H2 adsorption in SWNTs (produced by the arc-discharge method and purified), at 77K and moderate pressure (<20 atm.) We characterized the materials by HRTEM, Raman Spectroscopy and N2 adsorption isotherms, in order to determine the morphology and texture of sample for gas storage. HRTEM and temperature programed oxidation (TPO) results showed that the purified samples were clean from amorphous carbon, multishell carbons (MSC) and catalyst particles. In certain cases, HRTEM shows the tubes are in tact, while in other cases, it is observed that openings in the wall are created, and/or the tubes are cut into short tubelets. N2 adsorption studies allow us to obtain the specific surface area (SSA) and approximate pore size distribution. After purification, the SSA increases from ~280 m^2/g to 470 m^2/g. Measurements of H2 adsorption were performed in order to evaluate the adsorption capacity of the nanotubes at 77K and below 20 bar. We found up to 6 wt% H2 adsorbed in our purified material. (Work supported by Honda Motors R&D Co.)

  6. An amperometric hydrogen peroxide biosensor based on Co3O4 nanoparticles and multiwalled carbon nanotube modified glassy carbon electrode

    NASA Astrophysics Data System (ADS)

    Kaçar, Ceren; Dalkiran, Berna; Erden, P?nar Esra; Kiliç, Esma

    2014-08-01

    In this work a new type of hydrogen peroxide biosensor was fabricated based on the immobilization of horseradish peroxidase (HRP) by cross-linking on a glassy carbon electrode (GCE) modified with Co3O4 nanoparticles, multiwall carbon nanotubes (MWCNTs) and gelatin. The introduction of MWCNTs and Co3O4 nanoparticles not only enhanced the surface area of the modified electrode for enzyme immobilization but also facilitated the electron transfer rate, resulting in a high sensitivity of the biosensor. The fabrication process of the sensing surface was characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Amperometric detection of hydrogen peroxide was investigated by holding the modified electrode at -0.30 V (vs. Ag/AgCl). The biosensor showed optimum response within 5 s at pH 7.0. The optimized biosensor showed linear response range of 7.4 × 10-7-1.9 × 10-5 M with a detection limit of 7.4 × 10-7. The applicability of the purposed biosensor was tested by detecting hydrogen peroxide in disinfector samples. The average recovery was calculated as 100.78 ± 0.89.

  7. Single-wall carbon nanotube-based proton exchange membrane assembly for hydrogen fuel cells.

    PubMed

    Girishkumar, G; Rettker, Matthew; Underhile, Robert; Binz, David; Vinodgopal, K; McGinn, Paul; Kamat, Prashant

    2005-08-30

    A membrane electrode assembly (MEA) for hydrogen fuel cells has been fabricated using single-walled carbon nanotubes (SWCNTs) support and platinum catalyst. Films of SWCNTs and commercial platinum (Pt) black were sequentially cast on a carbon fiber electrode (CFE) using a simple electrophoretic deposition procedure. Scanning electron microscopy and Raman spectroscopy showed that the nanotubes and the platinum retained their nanostructure morphology on the carbon fiber surface. Electrochemical impedance spectroscopy (EIS) revealed that the carbon nanotube-based electrodes exhibited an order of magnitude lower charge-transfer reaction resistance (R(ct)) for the hydrogen evolution reaction (HER) than did the commercial carbon black (CB)-based electrodes. The proton exchange membrane (PEM) assembly fabricated using the CFE/SWCNT/Pt electrodes was evaluated using a fuel cell testing unit operating with H(2) and O(2) as input fuels at 25 and 60 degrees C. The maximum power density obtained using CFE/SWCNT/Pt electrodes as both the anode and the cathode was approximately 20% better than that using the CFE/CB/Pt electrodes. PMID:16114961

  8. Negative-ion production on carbon materials in hydrogen plasma: influence of the carbon hybridization state and the hydrogen content on H- yield

    NASA Astrophysics Data System (ADS)

    Ahmad, Ahmad; Pardanaud, Cédric; Carrère, Marcel; Layet, Jean-Marc; Gicquel, Alix; Kumar, Pravin; Eon, David; Jaoul, Cédric; Engeln, Richard; Cartry, Gilles

    2014-02-01

    Highly oriented polycrystalline graphite (HOPG), boron-doped diamond (BDD), nanocrystalline diamond, ultra-nanocrystalline diamond and diamond-like carbon surfaces are exposed to low-pressure hydrogen plasma in a 13.56 MHz plasma reactor. Relative yields of surface-produced H- ions due to bombardment of positive ions from the plasma are measured by an energy analyser cum quadrupole mass spectrometer. Irrespective of plasma conditions (0.2 and 2 Pa), HOPG surfaces show the highest yield at room temperature (RT), while at high temperature (HT), the highest yield (˜3-5 times compared to HOPG surface at RT) is observed on BDD surfaces. The shapes of ion distribution functions are compared at RT and HT to demonstrate the mechanism of ion generation at the surface. Raman spectroscopy analyses of the plasma-exposed samples reveal surface modifications influencing H- production yields, while further analyses strongly suggest that the hydrogen content of the material and the sp3/sp2 ratio are the key parameters in driving the surface ionization efficiency of carbon materials under the chosen plasma conditions.

  9. STEM Imaging of Single Pd Atoms in Activated Carbon Fibers Considered for Hydrogen Storage

    SciTech Connect

    Van Benthem, Klaus [University of California, Davis; Bonifacio, Cecile S [University of California, Davis; Contescu, Cristian I [ORNL; Pennycook, Stephen J [ORNL; Gallego, Nidia C [ORNL

    2011-01-01

    Aberration corrected scanning transmission electron microscopy was used to demonstrate the feasibility of imaging individual Pd atoms that are highly dispersed throughout the volume of activated carbon fibers. Simultaneous acquisition of high-angle annular dark-field and bright-field images allows correlation of the location of single Pd atoms with microstructural features of the carbon host material. Sub-Angstrom imaging conditions revealed that 18 wt% of the total Pd content is dispersed as single Pd atoms in three re-occurring local structural arrangements. The identified structural configurations may represent effective storage sites for molecular hydrogen through Kubas complex formation as discussed in detail in the preceding article.

  10. Lanthanum-hexaboride carbon composition for use in corrosive hydrogen-fluorine environments

    DOEpatents

    Holcombe, C.E. Jr.; Kovach, L.; Taylor, A.J.

    1980-01-22

    The present invention relates to a structural composition useful in corrosive hydrogen-fluorine environments at temperatures in excess of 1400/sup 0/K. The composition is formed of a isostatically pressed and sintered or a hot-pressed mixture of lanthanum hexaboride particles and about 10 to 30 vol% carbon. The lanthanum-hexaboride reacts with the high-temperature fluorine-containing gases to form an adherent layer of corrosion-inhibiting lanthanum trifluoride on exposed surfaces of the composition. The carbon in the composite significantly strengthens the composite, enhances thermal shock resistance, and significantly facilitates the machining of the composition.

  11. Plasma-deposited amorphous hydrogenated carbon films and their tribological properties

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Pouch, J. J.; Alterovitz, S. A.

    1989-01-01

    Recent work on the properties of diamondlike carbon films and their dependence on preparation conditions are reviewed. The results of the study indicate that plasma deposition enables one to deposit a variety of amorphous hydrogenated carbon (a-C:H) films exhibiting more diamondlike behavior to more graphitic behavior. The plasma-deposited a-C:H can be effectively used as hard, wear-resistant, and protective lubricating films on ceramic materials such as Si(sub 3)N(sub 4) under a variety of environmental conditions such as moist air, dry nitrogen, and vacuum.

  12. Production of thick single-walled carbon nanotubes by arc discharge in hydrogen ambience

    NASA Astrophysics Data System (ADS)

    Ando, Yoshinori; Zhao, Xinluo; Hirahara, Kaori; Iijima, Sumio

    2001-10-01

    High-quality single-walled carbon nanotubes (SWNTs) have been produced by DC arc discharge in hydrogen ambience. By using Fe 1% catalyst a large amount of SWNTs are produced in pure H2 gas. Other transition metals of iron group and its combination are also used as catalyst for preparing SWNTs by adding 1% H2S gas in H2. Tri-metal catalyst, Fe(0.25%)-Ni(0.9%)-Co(0.9%), is found to be most effective for high yield of SWNTs. The SWNTs diameters are fairly thick ˜1.4-4 nm, and some double-walled carbon nanotubes also exist with them.

  13. Carbon monoxide removal from hydrogen-rich fuel cell feedstreams by selective catalytic oxidation

    Microsoft Academic Search

    Se. H. Oh; R. M. Sinkevitch

    1993-01-01

    Indirect methanol fuel cells currently being investigated at General Motors for transportation applications require removal of carbon monoxide from the hydrogen-rich gas stream produced by the fuel processing section. A variety of catalytic materials, including noble metals (Pt, Pd, Rh, and Ru) and base metals (Co\\/Cu, Ni\\/Co\\/Fe, Ag, Cr, Fe, and Mn), were evaluated in a laboratory reactor feedstream containing

  14. Growth and structure of hydrogenated carbon films containing fullerene-like structure

    Microsoft Academic Search

    Peng Wang; Xia Wang; Weimin Liu; Junyan Zhang

    2008-01-01

    Hydrogenated carbon films were prepared by magnetron sputtering of a titanium target in methane and argon atmosphere. The film grown at -800 V bias exhibits excellent mechanical properties with a hardness of 20.9 GPa and an elastic recovery as high as 85%. Its structure, characterized by high-resolution transmission electron microscopy, Raman spectrum, and x-ray photoelectron spectroscopy, can be described as

  15. Production of activated carbon and its catalytic application for oxidation of hydrogen sulphide

    Microsoft Academic Search

    Ramin Azargohar

    2009-01-01

    Hydrogen sulphide is an environmentally hazardous gas which is present in many gas streams associated with oil and gas industry. Oxidation of H 2S to sulphur in air produces no bulky or waste material and requires no further purification. Activated carbon is known as a catalyst for this reaction. In this research, a coal-based precursor (luscar char) and a biomass-based

  16. Intrinsic stress and high temperature properties of metal-containing hydrogenated amorphous carbon coatings

    Microsoft Academic Search

    Bo Shi

    2005-01-01

    A detailed examination of the intrinsic stress development and mechanical properties of titanium-containing hydrogenated amorphous carbon (Ti-C:H) and W-C:H coatings, deposited in an inductively coupled plasma (ICP) assisted hybrid chemical\\/physical vapor deposition (CVD\\/PVD) environment was carried out. Intrinsic stresses within those coatings were found to be compressive and dependent on compositions. The intrinsic compression within Ti-C:H was further shown to

  17. Hydrogen, Methane and Carbon Dioxide Adsorption in Metal-Organic Framework Materials

    NASA Astrophysics Data System (ADS)

    Lin, Xiang; Champness, Neil R.; Schröder, Martin

    The role of porous coordination polymers (metal-organic frameworks) as storage materials for hydrogen, carbon dioxide and methane and the current state-of-the-art in this rapidly developing field are reviewed. The significant potential of porous materials to store fuel gases effectively and reversibly illustrates the great promise of engineered solid-state materials as the next generations of applied multi-functional materials.

  18. Gas turbine combustion performance test of hydrogen and carbon monoxide synthetic gas

    Microsoft Academic Search

    Min Chul Lee; Seok Bin Seo; Jae Hwa Chung; Si Moon Kim; Yong Jin Joo; Dal Hong Ahn

    2010-01-01

    The development of coal IGCC (Integrated Gasification Combined Cycle) technology has made it possible to exploit electricity generated from coal at a low cost. Furthermore, IGCC is a pre-requisite for the development of CCS (Carbon Capture and Storage) technology and hydrogen generated from coal. To achieve the need to reduce CO2 emissions, Korea’s 300MW IGCC RDD&D (Research Development, Demonstration and

  19. Hydrogen peroxide sensor based on glassy carbon electrode modified with ?-manganese dioxide nanorods

    Microsoft Academic Search

    Ai-Jun Wang; Pei-Pei Zhang; Yong-Fang Li; Jiu-Ju Feng; Wen-Ju Dong; Xue-Yan Liu

    A novel sensor for hydrogen peroxide (H2O2) was fabricated using ?-MnO2 nanorods on a glassy carbon electrode (GCE). The nanorods were obtained by a hydrothermal method and characterized by scanning\\u000a electron microscopy and X-ray diffraction. Cyclic voltammetry was used to evaluate the electrochemical performance of the\\u000a modified GCE. The sensor exhibits excellent catalytic activity toward the oxidation of H2O2 and

  20. Molecular simulation of the solubility and diffusion of carbon dioxide and hydrogen sulfide in polyethylene melts

    Microsoft Academic Search

    François Faure; Bernard Rousseau; V ´ eronique Lachet; Philippe Ungerer

    2007-01-01

    We present molecular simulation results of solubility and self-diffusion of carbon dioxide and hydrogen sulfide in linear polyethylene melts. Simulations were carried out at 433?K and pressures in the range 0.1–10?MPa. Solubilities were computed using Monte Carlo simulations in the osmotic ensemble, with constant number of polymer chains, pressure, temperature and gases chemical potential. Diffusion coefficients were obtained from equilibrium

  1. Electrochemical hydrogen storage behaviors of CVD, AD and LA grown carbon nanotubes in KOH medium

    Microsoft Academic Search

    A. K. M. Fazle Kibria; Y. H. Mo; K. S. Park; K. S. Nahm; M. H. Yun

    2001-01-01

    Carbon nanotubes (CNTs) were synthesized catalytically by both chemical vapor deposition (CVD) method in C2H2\\/H2 atmosphere at 600°C and arc-discharge (AD) method under helium atmosphere. The structure and morphology of CNTs was determined employing scanning electron microscopy (SEM) and FT-Raman spectroscopy. Hydrogen storage capacities were electrochemically measured for undoped and alkali metal (Li, Na and K) doped CVD, AD and

  2. Carbon and hydrogen isotopic composition of methane over the last 1000 years

    Microsoft Academic Search

    J. A. Mischler; T. A. Sowers; R. B. Alley; M. Battle; J. R. McConnell; L. Mitchell; T. Popp; E. Sofen; M. K. Spencer

    2009-01-01

    New measurements of the carbon and hydrogen isotopic ratios of methane (?13C of CH4 and ?D of CH4) over the last millennium are presented from the WAIS Divide, Antarctica, ice core (WDC05A), showing significant changes that likely were the result of human influences prior to the industrial revolution (at least as early as the 16th century of the common era

  3. Hydrogen photoproduction and carbon dioxide uptake by immobilized Anabaena variabilis in a hollow-fiber photobioreactor

    Microsoft Academic Search

    Sergei A. Markov; Michael J. Bazin; David O. Hall

    1995-01-01

    Hydrogen (H2) photoproduction and carbon dioxide (CO2) uptake by the cyanobacterium Anabaena variabilis was measured under partial vacuum in batch culture and in a photobioreactor. Increasing CO2 concentrations in the gas phase led to decreased H2 photoproduction and increased CO2 uptake by the cells, which was accompanied by O2 evolution.A laboratory-scale hollow-fiber photobioreactor was constructed for the production of H2

  4. Hydrogen production from biomass coupled with carbon dioxide capture: The implications of thermodynamic equilibrium

    Microsoft Academic Search

    Nicholas H. Florin; Andrew T. Harris

    2007-01-01

    In this work we report on the consequences of thermodynamic equilibrium for hydrogen (H2) generation via steam gasification of biomass, coupled with in situ carbon dioxide (CO2) capture. Calcium oxide (CaO) is identified as a suitable sorbent for CO2 capture, capable of absorbing CO2 to very low concentrations, at temperatures and pressures conducive to the gasification of biomass. The proposed

  5. Carbon nanofibers supported nickel catalyst for liquid phase hydrogenation of benzene with high activity and selectivity

    Microsoft Academic Search

    Pingle Liu; Huan Xie; Shirong Tan; Kuiyi You; Nailiang Wang; He’an Luo

    2009-01-01

    Carbon nanofibers (CNFs) prepared by catalytic decomposition of ethylene are used as support for nickel. The CNF support displays\\u000a a mean diameter of 50–60 nm, lengths up to several tens of micrometers, as highlighted by TEM. The nickel particles have a\\u000a size distribution from 10 to 20 nm of diameter. This novel Ni\\/CNFs catalyst displays good catalytic properties in liquid phase\\u000a hydrogenation

  6. On carbonaceous deposit formation in carbon monoxide hydrogenation on a natural iron catalyst

    Microsoft Academic Search

    Alfonso Loaiza-Gil; Bernardo Fontal; Fulgencio Rueda; Juan Mendialdua; Rodrigo Casanova

    1999-01-01

    During carbon monoxide hydrogenation on a natural iron catalyst, two different behaviors were observed when the operating pressure was changed from 3.5 to 20.4bar at 513K and inlet H2\\/CO of 2.0.A gradual increase in the catalyst activity to a maximum followed by a gradual loss in activity was observed at lower operating pressure. The surface composition (XPS) for the used

  7. Fractography of the high temperature hydrogen attack of a medium carbon steel

    NASA Technical Reports Server (NTRS)

    Melson, H. G.; Moorhead, R. D.

    1975-01-01

    Microscopic fracture processes were studied which are associated with hydrogen attack of a medium carbon steel in a well-controlled, high-temperature, high-purity hydrogen environment. Exposure to a hydrogen pressure and temperature of 3.5 MN/m2 and 575 C was found to degrade room temperature tensile properties with increasing exposure time. After 408 hr, yield and ultimate strengths were reduced by more than 40 percent and elongation was reduced to less than 2 percent. Initial fissure formation was found to be associated with manganese rich particles, most probably manganese oxide, aligned in the microstructure during the rolling operation. Fissure growth was found to be associated with a reduction in carbide content of the microstructure and was inhibited by the depletion of carbon. The interior surfaces of sectioned fissures or bubbles exhibit both primary and secondary cracking by intergranular separation. The grain surfaces were rough and rounded, suggesting a diffusion-associated separation process. Specimens that failed at room temperature after exposure to hydrogen were found to exhibit mixed mode fracture having varying amounts of intergranular separation, dimple formation, and cleavage, depending on exposure time.

  8. Electrical properties of hydrogenated microcrystalline silicon carbon alloys: effect of deposition parameters and light soaking

    NASA Astrophysics Data System (ADS)

    Gaiaschi, S.; Gueunier-Farret, M.-E.; Longeaud, C.; Johnson, E. V.

    2015-07-01

    New materials with electrical properties similar to those of hydrogenated amorphous silicon (a-Si:H) or hydrogenated amorphous silicon germanium alloys, but that are stable under light soaking, could be a breakthrough for multi-junction thin-film silicon solar cell technology. With this aim, hydrogenated microcrystalline silicon-carbon alloy (? c-\\text{S}{{\\text{i}}1-x}{{\\text{C}}x} :H) thin films seem like promising candidates as the variation of the carbon in the alloy composition can be used to tune the effective bandgap, keeping a high crystalline fraction. In this study, a highly hydrogen-diluted silane and methane gas mixture was used to deposit ? c-\\text{S}{{\\text{i}}1-x}{{\\text{C}}x} :H thin films by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD). The effect of the independent variation of three deposition parameters (variation of methane flow rate, addition of a small amount of silicon tetrafluoride and variation of the RF-power density) on the electronic transport and defect properties was investigated. Selected samples were studied in their ‘as deposited’ state, after light soaking until saturation, and after a high temperature annealing. Particular care was paid to comparing the behaviour of this new material system to that of a reference a-Si:H sample, deposited by standard RF-PECVD.

  9. Catalytic conversion of hydrocarbons to hydrogen and high-value carbon

    DOEpatents

    Shah, Naresh; Panjala, Devadas; Huffman, Gerald P.

    2005-04-05

    The present invention provides novel catalysts for accomplishing catalytic decomposition of undiluted light hydrocarbons to a hydrogen product, and methods for preparing such catalysts. In one aspect, a method is provided for preparing a catalyst by admixing an aqueous solution of an iron salt, at least one additional catalyst metal salt, and a suitable oxide substrate support, and precipitating metal oxyhydroxides onto the substrate support. An incipient wetness method, comprising addition of aqueous solutions of metal salts to a dry oxide substrate support, extruding the resulting paste to pellet form, and calcining the pellets in air is also discloses. In yet another aspect, a process is provided for producing hydrogen from an undiluted light hydrocarbon reactant, comprising contacting the hydrocarbon reactant with a catalyst as described above in a reactor, and recovering a substantially carbon monoxide-free hydrogen product stream. In still yet another aspect, a process is provided for catalytic decomposition of an undiluted light hydrocarbon reactant to obtain hydrogen and a valuable multi-walled carbon nanotube coproduct.

  10. Superlow friction of titanium/silicon codoped hydrogenated amorphous carbon film in the ambient air

    SciTech Connect

    Jiang Jinlong [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Department of Physics, Lanzhou University of Technology, Lanzhou 730050 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China); Hao Junying; Wang Peng; Liu Weimin [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2010-08-15

    Titanium/silicon codoped hydrogenated carbon film was deposited on the n-Si (100) substrates by reactive magnetron sputtering Ti80Si20 target in a mixture of argon and methane. Microstructure of the film was investigated using x-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, Raman spectroscopy, and attenuated total reflectance Fourier transform infrared spectroscopy. The investigations have revealed that the film has an amorphous structure and consists of high sp{sup 2} hybridized carbon atoms and bonding hydrogen atoms. The mechanical and tribological properties were evaluated using a nanoindentor and a ball-on-disk tribometer, respectively. The film exhibits hardness of 9.6 GPa, high elastic recovery of 73.0% and high H/E ratio of 0.156. Most significant, the superlow friction ({mu}<0.01) and special low wear rate (2.4x10{sup -7} mm{sup 3} N{sup -1} m{sup -1}) was observed in ambient air with 40% relative humidity. Combining the results of scanning electron microscopy and Raman analyses of the worn surface, it is concluded that some mechanisms, e.g., transfer films, friction-induced graphitization, hydrogen-terminated carbon surface, tribochemical reaction, etc., could be together responsible for this superlow friction in the ambient air.

  11. The potential energy curve and Langmuir isotherm of hydrogen adsorption by a truncated carbon sphere

    NASA Astrophysics Data System (ADS)

    Ishikawa, Shigeru; Yamabe, Tokio

    2015-06-01

    The potential energy curve for the adsorption of a hydrogen molecule by a truncated hollow sphere consisting of carbon atoms was evaluated by using the Lennard-Jones function for the pair interaction between a carbon atom and a hydrogen molecule. The sphere surface was regarded as a continuum with a uniform density identical to that of a graphite layer. The lower limit of the potential was found to be -200 meV when the sphere had a radius of 3.4 Å and no opening. By increasing the radius of the opening to 2.9 Å, the energy barrier for an incoming molecule disappeared and the lower limit increased to -150 meV, which is three times as deep as that observed for a graphite surface. The Langmuir isotherm for the truncated sphere of this size was evaluated based on the eigenvalues of the potential curve. We found that the pressure yielding a half occupancy was <50 bar at a temperature below 250 K. This indicates that a carbon pore with this shape and size can store a hydrogen molecule under mild conditions.

  12. Carbon and hydrogen isotope fractionation under continuous light: implications for paleoenvironmental interpretations of the High Arctic during Paleogene warming

    Microsoft Academic Search

    Hong Yang; Mark Pagani; Derek E. G. Briggs; M. A. Equiza; Richard Jagels; Qin Leng; Ben A. LePage

    2009-01-01

    The effect of low intensity continuous light, e.g., in the High Arctic summer, on plant carbon and hydrogen isotope fractionations\\u000a is unknown. We conducted greenhouse experiments to test the impact of light quantity and duration on both carbon and hydrogen\\u000a isotope compositions of three deciduous conifers whose fossil counterparts were components of Paleogene Arctic floras: Metasequoia glyptostroboides, Taxodium distichum, and

  13. Effect of the hydrogenating component of bifunctional zeolitecontaining catalysts on the composition of the hydrogenation products of carbon monoxide

    SciTech Connect

    Ivanova, A.S.; Egorova, L.S.; Ione, K.G.; Poshis, A.V.

    1985-09-01

    This paper presents a study on the Fe/M ratio, where M is a group V-VIII metal in bifunctional zeolite-containing catalysts on the composition of the hydrocarbon products of the hydrogenation of carbon monoxide under different reaction conditions. Additives introduced into the iron-containing component may be divided into two groups: group I) Mn, V. and Mn-V facilitate an enhancement of the products in the epsilonC/sub 5/+ fraction and group II) Sb, ce, cu, Mo and Mn-Mo which gave an enhancement in the volatile hydrocarbon fraction epsilonC/sub 2/-C/sub 4/. The nature of the zeolite (high-silicon or erionite) affects the selectivity of the transformation of CO and H/sub 2/.

  14. [Removal of fluorescent whitening agent by hydrogen peroxide oxidation catalyzed by activated carbon].

    PubMed

    Liu, Hai-Long; Zhang, Zhong-Min; Zhao, Xia; Jiao, Ru-Yuan

    2014-06-01

    Degradation of fluorescent whitening agent VBL in the processes of activated carbon (AC) and activated carbon modified (ACM) adsorptions, hydrogen peroxide (H2O2) oxidation, and hydrogen peroxide oxidation catalyzed by activated carbon were studied. Mechanism of the above catalytic oxidation was also investigated by adding tert-Butyl alcohol (TBA), the free radical scavenger, and detecting the released gases. The results showed that: the activated carbon modified by Fe (NO3)3 (ACM)exhibited better adsorption removal than AC. Catalytic oxidation showed efficient removal of VBL, and the catalytic removal of AC (up to 95%) was significantly higher than that of ACM (58% only). Catalytic oxidation was inhibited by TBA, which indicates that the above reaction involved *OH radicals and atom oxygen generated by hydrogen peroxide with the presence of AC. The results of H2O2 decomposition and released gases detection involved in the process showed that activated carbon enhanced the decomposition of H2O2 which released oxygen and heat. More O2 was produced and higher temperature of the reactor was achieved, which indicated that H2O2 decomposition catalyzed by ACM was significantly faster than that of AC. Combining the results of VBL removal, it could be concluded that the rate of active intermediates (*OH radicals and atom oxygen) production by ACM catalytic reaction was faster than that of AC. These intermediates consumed themselves and produced O2 instead of degrading VBL. It seemed that the improper mutual matching of the forming rate of activating intermediates and the supply rate of reactants was an important reason for the lower efficiency of ACM catalytic reaction comparing with AC. PMID:25158496

  15. Coulometric titrations of bases in propylene carbonate using hydrogenpalladium and deuteriumpalladium generator electrodes.

    PubMed

    Mihajlovi?, R P; Jaksi?, L N; Vajgand, V V

    1992-12-01

    The application of hydrogen and deuterium ions obtained by anodic oxidation of hydrogen and deuterium dissolved in palladium, for the coulometric determination of bases (both individual and in mixtures) in propylene carbonate, is described. The current-potential curves at a palladium anode for supporting electrolyte indicator, titrated bases, hydrogen dissolved in palladium and deuterium dissolved in palladium showed that hydrogen and deuterium are oxidized at much less positive potentials than the oxidation potentials of other substances present in the solution. The generated H(+) and D(+) ions were used for the titration of bases (pyridine, quinoline, triethylamine, n-butylaniline, 2,2'-dipiridyl and aminopyrine) with visual and potentiometric detection. The oxidation of hydrogen and deuterium proceeded with 100% current efficiency. Two-component mixtures of bases (aliphatic + aromatic amine) were titrated successfully by using two indicators, Eosin and Crystal Violet. The relative error of the determination with respect to each individual base determination, was less than 2.5% for quantities of bases ranging from 1 to 3 mg. PMID:18965575

  16. The effect of hydrogen bonds on diffusion mechanism of water inside single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Chen, Qu; Wang, Qi; Liu, Ying-Chun; Wu, Tao

    2014-06-01

    Nanopores can serve as a molecule channel for transport of fluid, where water diffusion differs remarkably from that of simple particles. Hydrogen bonds play an essential role in the diffusion anomaly. Detailed investigations are carried out on the systems of rigid (6, 6), (7, 7), (8, 8), (9, 9), and (10, 10) armchair carbon nanotubes, solvated with Lennard-Jones water fluids. The role of hydrogen bonds is examined by diffusivity statistics and animation snapshots. It is found that in small (6,6) CNT, hydrogen bonds tend to aggregate water into a wire and lead to rapid collective drift. Confinement can stabilize the hydrogen bond of water molecules and enhance its lifetime. In relatively smaller CNTs, the diffusion mechanism could be altered by the temperature. Moreover, in larger nanotubes hydrogen bonding network allows the water to form regional concentrated clusters. This allows water fluid in extremely low density exhibit rather slow self-diffusion motion. This fundamental study attempts to provide insights in understanding nanoscale delivery system in aqueous solution.

  17. Biological sulfate reduction using gas-lift reactors fed with hydrogen and carbon dioxide as energy and carbon source

    SciTech Connect

    Houten, R.T. van; Hulshoff Pol, L.W.; Lettinga, G. (Wageningen Agricultural Univ. (Netherlands). Dept. of Environmental Technology)

    1994-08-20

    Feasibility and engineering aspects of biological sulfate reduction in gas-lift reactors were studied. Hydrogen and carbon dioxide were used as energy and carbon source. Attention was paid to biofilm formation, sulfide toxicity, sulfate conversion rate optimization, and gas-liquid mass transfer limitations. Sulfate-reducing bacteria formed stable biofilms on pumice particles. Biofilm formation was not observed when basalt particles were used. However, use of basalt particles led to the formation of granules of sulfate-reducing biomass. The sulfate-reducing bacteria, grown on pumice, easily adapted to free H[sub 2]S concentrations up to 450 mg/L. Biofilm growth rate then equilibrated biomass loss rate. These high free H[sub 2]S concentrations caused reversible inhibition rather than acute toxicity. When free H[sub 2]S concentrations were kept below 450 mg/L, a maximum sulfate conversion rate of 30 g SO[sub 4][sup 2[minus

  18. Effects of hydrogen on the physical and mechanical properties of carbide derived carbon

    NASA Astrophysics Data System (ADS)

    White, Christopher

    Carbide-derived carbon (CDC) is a form of carbon produced by reacting metal carbides, such as SiC, with halogens at temperatures high enough to produce fast kinetics, but too low to permit the re-arrangement of the carbon atoms into an equilibrium graphitic structure. The structure of CDC is derivative of the original carbide structure and contains nanoscale porosity and both sp2 and sp3 bonded carbon in a variety of nanoscale structures. CDC can be produced as a thin film on hard carbides to improve their tribological performance. CDC coatings are distinguished by their low friction coefficients and high wear resistance in many important industrial environments and by their resistance to spallation and delamination. The tribology of the CDC can be affected by varying the conditions employed during the chlorination process. Varying the exposure time, temperature and chlorine concentration in the treatment gas can alter these properties. When hydrogen is introduced during treatment, or afterwards as a subsequent post-treatment, the properties of the CDC layer are modified, which further improves the tribological performance. These modifications help to reduce energy loss and result in a decrease in the rate of wear during sliding applications. The physical and mechanical properties of hydrogen enhanced CDC coatings on SiC surfaces are described in detail.

  19. Nanopore structure from USAXS/SAXS in advanced carbon materials for hydrogen storage

    NASA Astrophysics Data System (ADS)

    Kraus, Michael; Beckner, M.; Stalla, D.; Wexler, C.; Pfeifer, P.; Ilavsky, J.

    2010-03-01

    Despite their mass-production and industrial use, there is still no generally accepted structural model of non-graphitizing activated carbons. We will show how USAXS/SAXS can be used to estimate the average shape and size of nanopores in amorphous carbon used for methane and hydrogen storage. Simulated scattering curves constructed from explicit experimental N2 isotherm pore size distributions reveal that nanoporous activated carbons scatter as correlated networks of pores with scattered intensities that depend largely on sample porosity. Graphical methods will be used to show how porosity can be calculated from SAXS data, using minimal model-dependent assumptions. The results are shown to be in excellent agreement with porosity values measured via N2 sorption isotherms.

  20. Dissolution of Irradiated Commercial UO2 Fuels in Ammonium Carbonate and Hydrogen Peroxide

    SciTech Connect

    Soderquist, Chuck Z.; Johnsen, Amanda M.; McNamara, Bruce K.; Hanson, Brady D.; Chenault, Jeffrey W.; Carson, Katharine J.; Peper, Shane M.

    2011-01-18

    We propose and test a disposition path for irradiated nuclear fuel using ammonium carbonate and hydrogen peroxide media. We demonstrate on a 13 g scale that >98% of the irradiated fuel dissolves. Subsequent expulsion of carbonate from the dissolver solution precipitates >95% of the plutonium, americium, curium, and substantial amounts of fission products, effectively partitioning the fuel at the dissolution step. Uranium can be easily recovered from solution by any of several means, such as ion exchange, solvent extraction, or direct precipitation. Ammonium carbonate can be evaporated from solution and recovered for re-use, leaving an extremely compact volume of fission products, transactinides, and uranium. Stack emissions are predicted to be less toxic, less radioactive, chemically simpler, and simpler to treat than those from the conventional PUREX process.

  1. Carbon acceptors and carbon-hydrogen complexes in AlSb M. D. McCluskey*

    E-print Network

    McCluskey, Matthew

    by annealing p-type AlSb in hydrogen gas, yielding a C-H stretch mode at 2566.6 cm 1 . Our results indicate LVM that is observed with Fourier-transform infra- red FTIR spectroscopy. A similar situation occurs residual contaminant in semi-insulating material.8 The substitutional acceptors 12 CAs and 13 CAs give rise

  2. Strong interaction effects in kaonic deuterium

    NASA Astrophysics Data System (ADS)

    Barrett, R. C.; Deloff, A.

    1999-08-01

    High precision measurements of kaonic hydrogen x rays and also, for the first time, of kaonic deuterium are under way within the DEAR project using the e+e- storage ring at Frascati. The values of the strong interaction 1s level shift and width in kaonic deuterium cannot be simply predicted by relating them, via the Deser-Trueman formula, to the K-d scattering length because the latter is not known experimentally: it cannot be obtained by adding the K-p and K-n scattering lengths but involves the solution of a complicated multichannel three-body problem. We give results of calculations of the kaonic deuterium strong interaction shift and width using an (NK¯,Y?) interaction (Y=?,?) that fits the available low-energy scattering data. The 1s level shift in kaonic deuterium comes out negative and both the shift and the width are estimated to be about 1 keV. The 2p capture rate is estimated to be smaller than the 2p-->1s x-ray transition rate. This information is of importance for the planned experiment as it indicates that most of the kaons should reach the lowest 1s level.

  3. Hydrogen storage in carbon nitride nanobells X. D. Bai, Dingyong Zhong, G. Y. Zhang, X. C. Ma, Shuang Liu, and E. G. Wanga)

    E-print Network

    Zhang, Guangyu

    Hydrogen storage in carbon nitride nanobells X. D. Bai, Dingyong Zhong, G. Y. Zhang, X. C. Ma as hydrogen adsorbent. A hydrogen storage capacity up to 8 wt % was achieved reproducibly under ambient pressure and at temperature of 300 °C. The high hydrogen storage capacity under the moderate conditions

  4. Molecular simulation studies of adsorption of hydrogen cyanide and methyl ethyl ketone on zeolite NaX and activated carbon

    Microsoft Academic Search

    R. R. Kotdawala; Nikolaos Kazantzis; Robert W. Thompson

    2008-01-01

    In the present research study the primary aim is to understand and characterize the physical adsorption of polar molecules namely, hydrogen cyanide and methyl ethyl ketone (MEK) in zeolite NaX, and activated carbon through detailed Monte–Carlo simulations and computational quantum chemistry techniques. The sorption capacity and affinity of the zeolite is compared with activated carbon with different acid site concentrations,

  5. Performance of carbon-based hot frit substrates. 2, Coating performance studies in hydrogen at atmospheric pressure

    SciTech Connect

    Barletta, R.; Vanier, P.; Adams, J.; Svandrlik, J.; Powell, J.R.

    1993-07-01

    Erosion tests were conducted on coated graphite and 2D, 3D carbon- carbons in 1 atm hydrogen at high temperatures. Refractory NbC, TaC coatings were used. It was found that the most effective combination of coating and substrate was TaC deposited by chemical vapor reaction method on AXF-5QI graphite.

  6. Evaluation of energy integration aspects for IGCC-based hydrogen and electricity co-production with carbon capture and storage

    Microsoft Academic Search

    Calin-Cristian Cormos

    2010-01-01

    Integrated Gasification Combined Cycle (IGCC) is a power generation technology in which the solid feedstock is partially oxidized with oxygen and steam to produce syngas. In a conventional IGCC design without carbon capture, the syngas is purified for dust and hydrogen sulphide removal and then sent to a Combined Cycle Gas Turbine (CCGT) for power generation. Carbon capture technologies are

  7. Tritium catalyzed deuterium tokamaks

    SciTech Connect

    Greenspan, E.; Miley, G.H.; Jung, J.; Gilligan, J.

    1984-04-01

    A preliminary assessment of the promise of the Tritium Catalyzed Deuterium (TCD) tokamak power reactors relative to that of deuterium-tritium (D-T) and catalyzed deuterium (Cat-D) tokamaks is undertaken. The TCD mode of operation is arrived at by converting the /sup 3/He from the D(D,n)/sup 3/He reaction into tritium, by neutron capture in the blanket; the tritium thus produced is fed into the plasma. There are three main parts to the assessment: blanket study, reactor design and economic analysis and an assessment of the prospects for improvements in the performance of TCD reactors (and in the promise of the TCD mode of operation, in general).

  8. Hydrogen from Coal Edward Schmetz

    E-print Network

    Turbines Carbon Capture & Sequestration Carbon Capture & Sequestration The Hydrogen from Coal Program Cells, Turbines, and Carbon Capture & Sequestration #12;Production Goal for Hydrogen from Coal Central Separation System PSA Membrane Membrane Carbon Sequestration Yes (87%) Yes (100%) Yes (100%) Hydrogen

  9. Stability of electron emission current in hydrogen-free diamond-like carbon deposited by plasma enhanced chemical vapor deposition

    SciTech Connect

    Chung, S.J.; Moon, J.H.; Park, K.C. [Department of Physics, Kyung Hee University, Dongdaemoon-ku, Seoul 130-701 (Korea)] [Department of Physics, Kyung Hee University, Dongdaemoon-ku, Seoul 130-701 (Korea); Oh, M.H. [Korea Institute of Science and Technology, P.O. Box 131 (Korea)] [Korea Institute of Science and Technology, P.O. Box 131 (Korea); Milne, W.I. [University of Cambridge, Trumpington Street, Cambridge CB2 1PZ (United Kingdom)] [University of Cambridge, Trumpington Street, Cambridge CB2 1PZ (United Kingdom); Jang, J. [Department of Physics, Kyung Hee University, Dongdaemoon-ku, Seoul 130-701 (Korea)] [Department of Physics, Kyung Hee University, Dongdaemoon-ku, Seoul 130-701 (Korea)

    1997-10-01

    We have studied the electron emission characteristics of the hydrogen-free diamondlike carbon (DLC) and conventional DLC films. The electron emission current of conventional DLC increases at first and then decreases continuously with bias stress time. The emission current of the hydrogen-free DLC, deposited by the layer-by-layer technique, increases at first and then stabilizes with increasing stress time. The resistivity of the hydrogen-free DLC decreases after long bias stress, and that appears to be due to the changes in the density of states in the gap of the hydrogen-free DLC. {copyright} {ital 1997 American Institute of Physics.}

  10. Deuterium Retention in NSTX with Lithium Conditioning

    SciTech Connect

    C.H. Skinner, J.P. Allain, W. Blanchard, H.W. Kugel, R. Maingi, L. Roquemore, V. Soukhanovskii, C.N. Taylor

    2010-06-02

    High (? 90%) deuterium retention was observed in NSTX gas balance measurements both withand without lithiumization of the carbon plasma facing components. The gas retained in ohmic discharges was measured by comparing the vessel pressure rise after a discharge to that of a gasonly pulse with the pumping valves closed. For neutral beam heated discharges the gas input and gas pumped by the NB cryopanels were tracked. The discharges were followed by outgassing of deuterium that reduced the retention. The relationship between retention and surface chemistry was explored with a new plasma-material interface probe connected to an in-vacuo surface science station that exposed four material samples to the plasma. XPS and TDS analysis showed that the binding of D atoms is fundamentally changed by lithium - in particular atoms are weakly bonded in regions near lithium atoms bound to either oxygen or the carbon matrix.

  11. The effect of KOH:C and activation temperature on hydrogen storage capacities of activated carbons

    NASA Astrophysics Data System (ADS)

    Rash, Tyler; Beckner, Matt; Romanos, Jimmy; Leimkuehler, Eric; Takeei, Ali; Suppes, Galen; Wexler, Carlos; Pfeifer, Peter

    2011-03-01

    The Alliance for Collaborative Research in Alternative Fuel Technologies (ALL-CRAFT has been producing high surface area activated carbons. Here we will investigate the effect of the ratio of activating agent to carbon and activation temperature on hydrogen sorption characteristics and sample structure. Results show that a ratio of 3:1 KOH:C and an activation temperature of 790 C are the ideal activation conditions for hydrogen storage applications. Hydrogen sorption measurements are completed using a volumetric instrument that operates at pressures up to 100 bar and at temperatures of 80 K, the sublimation temperature of dry ice (-78.5 C), and room temperature. Specific surface area and pore size distributions are measured using subcritical nitrogen isotherms. This material is based on work supported by the US Department of Defense under Awards No. N00164-07-P-1306 and N00164-08-C-GS37, the US Department of Energy under Awards No. DE-FG02-07ER46411 and DE-FG36-08GO18142.

  12. The deuterium content of water in some volcanic glasses

    USGS Publications Warehouse

    Friedman, I.; Smith, R.L.

    1958-01-01

    The deuterium-hydrogen composition (relative to Lake Michigan water = 0.0) of water extractsd from coexisting perlite and obsidian from eleven different localities was determined. The water content of the obsidians is generally from 0.09 to 0.29 per cent by weight, though two samples from near Olancha, California, contain about 0.92 per cent. The relative deuterium concentration is from -4.6 to -12.3 per cent. The coexisting perlite contains from 2.0 to 3.8 per cent of water with a relative deuterium concentration of -3.1 to -16.6 per cent. The deuterium concentration in the perlites is not related to that in the enclosed obsidian. The deuterium concentration in the perlite water is related to the deuterium concentration of the modern meteoric water and the perlite water contains approximately 4 per cent less deuterium than does the groundwater of the area in which the perlites occur. The above relations hold true for perlites from northern New Mexico, east slope of the Sierra Nevada. California Coast Range, Yellowstone Park, Wyoming, and New Zealand. As the water in the obsidian is unrelated to meteoric water, but the enclosing perlite water is related, we believe that this is evidence for the secondary hydration of obsidian to form high water content perlitic glass. ?? 1958.

  13. Validation of KENO V.a for highly enriched uranium systems with hydrogen and\\/or carbon moderation

    Microsoft Academic Search

    E. P. Elliott; R. G. Vornehm; H. L. Jr. Dodds

    1993-01-01

    This paper describes the validation in accordance with ANSI\\/ANS-8.1-1983(R1988) of KENO V.a using the 27-group ENDF\\/B-IV cross-section library for systems containing highly-enriched uranium, carbon, and hydrogen and for systems containing highly-enriched uranium and carbon with high carbon to uranium (C\\/U) atomic ratios. The validation has been performed for two separate computational platforms: an IBM 3090 mainframe and an HP 9000

  14. Photocatalytic hydrogen evolution on dye-sensitized mesoporous carbon nitride photocatalyst with magnesium phthalocyanine.

    PubMed

    Takanabe, Kazuhiro; Kamata, Kumiko; Wang, Xinchen; Antonietti, Markus; Kubota, Jun; Domen, Kazunari

    2010-10-28

    Spectral sensitization of a mesoporous graphite carbon nitride (mpg-C(3)N(4)) photocatalyst was investigated by depositing magnesium phthalocyanine (MgPc) to expand the absorption to wavelengths longer than those of the principal mpg-C(3)N(4). The obtained sample, MgPc/Pt/mpg-C(3)N(4) (Pt as a cocatalyst) showed stable photocatalytic evolution of hydrogen from aqueous solution in the presence of sacrificial reagents (triethanolamine), even under irradiation at wavelengths longer than 600 nm. Increasing the amount of MgPc led to ordered MgPc aggregation on the photocatalyst surfaces. The rate of photocatalytic hydrogen evolution was highest on a sample with an amount of MgPc corresponding to a monolayer on the Pt/mpg-C(3)N(4) photocatalyst surface. The obtained action spectra of hydrogen evolution and the observation that the amount of evolved hydrogen substantially surpassed the amount of MgPc, confirm that the introduced MgPc functioned as a photocatalytic sensitizer. PMID:20820579

  15. Decorating multi-walled carbon nanotubes with nickel nanoparticles for selective hydrogenation of citral

    SciTech Connect

    Tang Yuechao; Yang Dong [Key Laboratory of Molecular Engineering of Polymers (Ministry of Education), Department of Macromolecular Science and Advanced Materials Laboratory, Fudan University, Shanghai 200433 (China); Qin Feng [Department of Chemistry, Fudan University, Shanghai 200433 (China); Hu Jianhua [Key Laboratory of Molecular Engineering of Polymers (Ministry of Education), Department of Macromolecular Science and Advanced Materials Laboratory, Fudan University, Shanghai 200433 (China); Wang Changchun, E-mail: ccwang@fudan.edu.c [Key Laboratory of Molecular Engineering of Polymers (Ministry of Education), Department of Macromolecular Science and Advanced Materials Laboratory, Fudan University, Shanghai 200433 (China); Xu Hualong [Department of Chemistry, Fudan University, Shanghai 200433 (China)

    2009-08-15

    The nanocomposites of multi-walled carbon nanotubes (MWNTs) decorated with nickel nanoparticles were conveniently prepared by a chemical reduction of nickel salt in the present of poly(acrylic acid) grafted MWNTs (PAA-g-MWNTs). Due to the strong interaction between Ni{sup 2+} and -COOH, PAA-g-MWNTs became an excellent supporting material for Ni nanoparticles. The morphology and distribution of Ni nanoparticles on the surface of MWNTs were greatly influenced by the reduction temperatures, the experimental results also showed that the distribution of Ni nanoparticles was greatly improved while the MWNTs were modified by poly(acrylic acid) (PAA). The hydrogenation activity and selectivity of MWNTs decorated with Ni nanoparticles (Ni-MWNTs) for alpha, beta-unsaturated aldehyde (citral) were also studied, and the experimental results showed that the citronellal, an important raw material for flavoring and perfumery industries, is the favorable product with a percentage as high as 86.9%, which is 7 times higher than that of catalyst by Ni-supported active carbon (Ni-AC). - Abstract: Nickel nanoparticles decorated multi-walled carbon nanotubes (Ni-MWNTs) nanocomposites were conveniently prepared by a chemical reduction of nickel salt in the present of poly(acrylic acid) grafted MWNTs (PAA-g-MWNTs). These nanocomposites possessed excellent catalytic activity and selectivity for hydrogenation of citral.

  16. Stable Isotope Measurements of Carbon Dioxide, Methane, and Hydrogen Sulfide Gas Using Frequency Modulation Spectroscopy

    NASA Astrophysics Data System (ADS)

    Nowak-Lovato, K.

    2014-12-01

    Seepage from enhanced oil recovery, carbon storage, and natural gas sites can emit trace gases such as carbon dioxide, methane, and hydrogen sulfide. Trace gas emission at these locations demonstrate unique light stable isotope signatures that provide information to enable source identification of the material. Light stable isotope detection through surface monitoring, offers the ability to distinguish between trace gases emitted from sources such as, biological (fertilizers and wastes), mineral (coal or seams), or liquid organic systems (oil and gas reservoirs). To make light stable isotope measurements, we employ the ultra-sensitive technique, frequency modulation spectroscopy (FMS). FMS is an absorption technique with sensitivity enhancements approximately 100-1000x more than standard absorption spectroscopy with the advantage of providing stable isotope signature information. We have developed an integrated in situ (point source) system that measures carbon dioxide, methane and hydrogen sulfide with isotopic resolution and enhanced sensitivity. The in situ instrument involves the continuous collection of air and records the stable isotope ratio for the gas being detected. We have included in-line flask collection points to obtain gas samples for validation of isotopic concentrations using our in-house isotope ratio mass spectroscopy (IRMS). We present calibration curves for each species addressed above to demonstrate the sensitivity and accuracy of the system. We also show field deployment data demonstrating the capabilities of the system in making live dynamic measurements from an active source.

  17. Physical Chemist Harold Clayton Urey (1893-1981) Columbia Chemistry Professor Harold Urey experimentally discovered deuterium

    E-print Network

    Physical Chemist Harold Clayton Urey (1893-1981) Columbia Chemistry Professor Harold Urey experimentally discovered deuterium in 1931. Early in that year Urey conceived and worked out a method hydrogen was distilled down to 1 cc. Urey detected deuterium by its predicted spectrum in a discharge

  18. What Is the Total Deuterium Abundance in the Local Galactic Disk?

    Microsoft Academic Search

    Jeffrey L. Linsky; Bruce T. Draine; H. W. Moos; Edward B. Jenkins; Brian E. Wood; Cristina Oliveira; William P. Blair; Scott D. Friedman; Cecile Gry; David Knauth; Jeffrey W. Kruk; Sylvestre Lacour; Nicolas Lehner; Seth Redfield; J. Michael Shull; George Sonneborn; Gerard M. Williger

    2006-01-01

    Analyses of spectra obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite, together with spectra from the Copernicus and interstellar medium absorption profile spectrograph (IMAPS) instruments, reveal an unexplained, very wide range in the observed deuterium\\/hydrogen (D\\/H) ratios for interstellar gas in the Galactic disk beyond the Local Bubble. We argue that spatial variations in the depletion of deuterium onto

  19. Covalent immobilization of protein onto a functionalized hydrogenated diamond-like carbon substrate.

    PubMed

    Biswas, Hari Shankar; Datta, Jagannath; Chowdhury, D P; Reddy, A V R; Ghosh, Uday Chand; Srivastava, Arvind Kumar; Ray, Nihar Ranjan

    2010-11-16

    Hydrogenated diamond-like carbon (HDLC) has an atomically smooth surface that can be deposited on high-surface area substrata and functionalized with reactive chemical groups, providing an ideal substrate for protein immobilization. A synthetic sequence is described involving deposition and hydrogenation of DLC followed by chemical functionalization. These functional groups are reacted with amines on proteins causing covalent immobilization on contact. Raman measurements confirm the presence of these surface functional groups, and Fourier transform infrared spectroscopy (FTIR) confirms covalent protein immobilization. Atomic force microscopy (AFM) of immobilized proteins is reproducible because proteins do not move as a result of interactions with the AFM probe-tip, thus providing an advantage over mica substrata typically used in AFM studies of protein. HDLC offers many of the same technical advantages as oxidized graphene but also allows for coating large surface areas of biomaterials relevant to the fabrication of medical/biosensor devices. PMID:20949913

  20. The reduction of carbon dioxide in iron biocatalyst catalytic hydrogenation reaction: a theoretical study.

    PubMed

    Yang, Longhua; Wang, Hongming; Zhang, Ning; Hong, Sanguo

    2013-08-21

    The reaction mechanism of CO? hydrogenation catalyzed by [FeH(PP?)]BF? (PP? = P(CH?CH?PPh?)?) had been investigated by DFT calculations. Our calculations indicated that the reduction of carbon dioxide could be carried out via two spin states, the high-spin (HS) triplet state and the low-spin (LS) singlet state. The minimum energy crossing points (MECPs) on the seam of two intersecting PESs (potential energy surfaces) were searched out. Some interesting phenomena, such as the open-loop phenomenon, and the O-rebound process, were demonstrated to be the important causes of the spin crossover. All these calculations gave us insight into the essence of the related experiment from the macro point of view, and helped to verify which spin states the related complexes pertinent were in. All of these researches would help advance the development of efficient and structurally tailorable CO? hydrogenation catalysts. PMID:23807290

  1. Optical properties of hydrogenated amorphous carbon films grown from methane plasma

    NASA Technical Reports Server (NTRS)

    Pouch, J. J.; Alterovitz, S. A.; Warner, J. D.; Liu, D. C.; Lanford, W. A.

    1985-01-01

    A 30 kHz ac glow discharge formed from methane gas was used to grow carbon films on InP substrates. Both the growth rate, and the realitive Ar ion sputtering rate at 3 keV varied monotonically with deposition power. Results from the N-15 nuclear reaction profile experiments indicated a slight drop in the hydrogen concentration as more energy was dissipated in the ac discharge. Values for the index of refraction and extinction coefficient ranged from 1.721 to 1.910 and 0 to -0.188, respectively. Optical bandgaps as high as 2.34 eV were determined.

  2. Two-dimensional gold nanostructures with high activity for selective oxidation of carbon–hydrogen bonds

    PubMed Central

    Wang, Liang; Zhu, Yihan; Wang, Jian-Qiang; Liu, Fudong; Huang, Jianfeng; Meng, Xiangju; Basset, Jean-Marie; Han, Yu; Xiao, Feng-Shou

    2015-01-01

    Efficient synthesis of stable two-dimensional (2D) noble metal catalysts is a challenging topic. Here we report the facile synthesis of 2D gold nanosheets via a wet chemistry method, by using layered double hydroxide as the template. Detailed characterization with electron microscopy and X-ray photoelectron spectroscopy demonstrates that the nanosheets are negatively charged and [001] oriented with thicknesses varying from single to a few atomic layers. X-ray absorption spectroscopy reveals unusually low gold–gold coordination numbers. These gold nanosheets exhibit high catalytic activity and stability in the solvent-free selective oxidation of carbon–hydrogen bonds with molecular oxygen. PMID:25902034

  3. Two-dimensional gold nanostructures with high activity for selective oxidation of carbon-hydrogen bonds

    NASA Astrophysics Data System (ADS)

    Wang, Liang; Zhu, Yihan; Wang, Jian-Qiang; Liu, Fudong; Huang, Jianfeng; Meng, Xiangju; Basset, Jean-Marie; Han, Yu; Xiao, Feng-Shou

    2015-04-01

    Efficient synthesis of stable two-dimensional (2D) noble metal catalysts is a challenging topic. Here we report the facile synthesis of 2D gold nanosheets via a wet chemistry method, by using layered double hydroxide as the template. Detailed characterization with electron microscopy and X-ray photoelectron spectroscopy demonstrates that the nanosheets are negatively charged and [001] oriented with thicknesses varying from single to a few atomic layers. X-ray absorption spectroscopy reveals unusually low gold-gold coordination numbers. These gold nanosheets exhibit high catalytic activity and stability in the solvent-free selective oxidation of carbon-hydrogen bonds with molecular oxygen.

  4. Catalytic hydrogenation of carbon monoxide. Progress report, December 15, 1991--December 14, 1992

    SciTech Connect

    Wayland, B.B.

    1992-12-01

    This project is focused on developing strategies to accomplish the reduction and hydrogenation of carbon monoxide to produce organic oxygenates at mild conditions. Our approaches to this issue are based on the recognition that rhodium macrocycles have unusually favorable thermodynamic values for producing a series of intermediate implicated in the catalytic hydrogenation of CO. Observations of metalloformyl complexes produced by reactions of H{sub 2} and CO, and reductive coupling of CO to form metallo {alpha}-diketone species have suggested a multiplicity of routes to organic oxygenates that utilize these species as intermediates. Thermodynamic and kinetic-mechanistic studies are used in constructing energy profiles for a variety of potential pathways, and these schemes are used in guiding the design of new metallospecies to improve the thermodynamic and kinetic factors for individual steps in the overall process. Variation of the electronic and steric effects associated with the ligand arrays along with the influences of the reaction medium provide the chemical tools for tuning these factors. Emerging knowledge of the factors that contribute to M-H, M-C and M-O bond enthalpies is directing the search for ligand arrays that will expand the range of metal species that have favorable thermodynamic parameters to produce the primary intermediates for CO hydrogenation. Studies of rhodium complexes are being extended to non-macrocyclic ligand complexes that emulate the favorable thermodynamic features associated with rhodium macrocycles, but that also manifest improved reaction kinetics. Multifunctional catalyst systems designed to couple the ability of rhodium complexes to produce formyl and diketone intermediates with a second catalyst that hydrogenates these imtermediates are promising approaches to accomplish CO hydrogenation at mild conditions.

  5. Hydrogen depolarized carbon dioxide concentrator performance improvements and cell pair structural tests. [for manned space station

    NASA Technical Reports Server (NTRS)

    Huddleston, J. D.; Aylward, J. R.

    1973-01-01

    The investigations and testing associated with the CO2 removal efficiency and voltage degradation of a hydrogen depolarized carbon oxide concentrator are reported. Also discussed is the vibration testing of a water vapor electrolysis cell pair. Performance testing of various HDC cell pairs with Cs2CO3 electrolyte provided sufficient parametric and endurance data to size a six man space station prototype CO2 removal system as having 36 HDC cell pairs, and to verify a life capability exceeding six moths. Testing also demonstrated that tetramethylammonium carbonate is an acceptable HDC electrolyte for operating over the relative humidity range of 30 to 90 percent and over a temperature range of 50 to 80 F.

  6. Sphalerite is a geochemical catalyst for carbon-hydrogen bond activation.

    PubMed

    Shipp, Jessie A; Gould, Ian R; Shock, Everett L; Williams, Lynda B; Hartnett, Hilairy E

    2014-08-12

    Reactions among minerals and organic compounds in hydrothermal systems are critical components of the Earth's deep carbon cycle, provide energy for the deep biosphere, and may have implications for the origins of life. However, there is limited information as to how specific minerals influence the reactivity of organic compounds. Here we demonstrate mineral catalysis of the most fundamental component of an organic reaction: the breaking and making of a covalent bond. In the absence of mineral, hydrothermal reaction of cis- and trans-1,2-dimethylcyclohexane is extremely slow and generates many products. In the presence of sphalerite (ZnS), however, the reaction rate increases dramatically and one major product is formed: the corresponding stereoisomer. Isotope studies show that the sphalerite acts as a highly specific heterogeneous catalyst for activation of a single carbon-hydrogen bond in the dimethylcyclohexanes. PMID:25071186

  7. Sphalerite is a geochemical catalyst for carbon?hydrogen bond activation

    PubMed Central

    Shipp, Jessie A.; Gould, Ian R.; Shock, Everett L.; Williams, Lynda B.; Hartnett, Hilairy E.

    2014-01-01

    Reactions among minerals and organic compounds in hydrothermal systems are critical components of the Earth’s deep carbon cycle, provide energy for the deep biosphere, and may have implications for the origins of life. However, there is limited information as to how specific minerals influence the reactivity of organic compounds. Here we demonstrate mineral catalysis of the most fundamental component of an organic reaction: the breaking and making of a covalent bond. In the absence of mineral, hydrothermal reaction of cis- and trans-1,2-dimethylcyclohexane is extremely slow and generates many products. In the presence of sphalerite (ZnS), however, the reaction rate increases dramatically and one major product is formed: the corresponding stereoisomer. Isotope studies show that the sphalerite acts as a highly specific heterogeneous catalyst for activation of a single carbon?hydrogen bond in the dimethylcyclohexanes. PMID:25071186

  8. Decontamination of adsorbed chemical warfare agents on activated carbon using hydrogen peroxide solutions.

    PubMed

    Osovsky, Ruth; Kaplan, Doron; Nir, Ido; Rotter, Hadar; Elisha, Shmuel; Columbus, Ishay

    2014-09-16

    Mild treatment with hydrogen peroxide solutions (3-30%) efficiently decomposes adsorbed chemical warfare agents (CWAs) on microporous activated carbons used in protective garments and air filters. Better than 95% decomposition of adsorbed sulfur mustard (HD), sarin, and VX was achieved at ambient temperatures within 1-24 h, depending on the H2O2 concentration. HD was oxidized to the nontoxic HD-sulfoxide. The nerve agents were perhydrolyzed to the respective nontoxic methylphosphonic acids. The relative rapidity of the oxidation and perhydrolysis under these conditions is attributed to the microenvironment of the micropores. Apparently, the reactions are favored due to basic sites on the carbon surface. Our findings suggest a potential environmentally friendly route for decontamination of adsorbed CWAs, using H2O2 without the need of cosolvents or activators. PMID:25133545

  9. Rh-catalyzed asymmetric hydrogenation of unsaturated lactate precursors in propylene carbonate.

    PubMed

    Schäffner, Benjamin; Andrushko, Vasyl; Holz, Jens; Verevkin, Sergey P; Börner, Armin

    2008-01-01

    The asymmetric hydrogenation of alpha-acetoxy acrylates to O-acetyl lactates with Rh catalysts based on chiral bisphospholane ligands was investigated in propylene carbonate (PC) as "green" solvent. In contrast to DuPHOS-type ligands, catASium M ligands lead to full conversion of the substrate in PC and induce excellent enantioselectivities for ethyl ester and methyl ester substrates (>98 %). Moreover, the undesired opening of the maleic anhydride moiety of the catASium M ligand observed in MeOH can be prevented under these conditions. The chiral product can be easily separated from the carbonate solvent by distillation. In this way, an ecologically benign process for the production of enantiopure lactic acid derivatives was established which offers a highly efficient catalytic transformation in a green solvent under mild conditions (1-10 bar H(2)). PMID:18956407

  10. Using deuterium in drug discovery: leaving the label in the drug.

    PubMed

    Gant, Thomas G

    2014-05-01

    Deuterium, the stable isotope of hydrogen, is known to medicinal chemists for its utility in mechanistic, spectroscopic, and tracer studies. In fact, well-known applications utilizing deuterium exist within every subdiscipline in pharmaceutical discovery and development. Recent emphasis on incorporation of deuterium into the active pharmaceutical ingredient has come about as a result of inquiries into the potential for substantial benefits of the deuterium kinetic isotope effect on the safety and disposition of the drug substance. This Perspective traces the author's experience in reviving and expanding this potential utility, first suggested many decades prior by the discoverer of this, the simplest of all isotopes. PMID:24294889

  11. Carbon Deposition on Iron–Nickel during Interaction with Carbon Monoxide–Hydrogen Mixtures

    Microsoft Academic Search

    N. M. Rodriguez; R. T. K. Baker

    1997-01-01

    We have found that the composition of Fe–Ni catalysts can have a profound effect on the activity for the decomposition of CO\\/H2mixtures at 600°C. As the fraction of nickel in the bimetallic is increased above 70% there is a significant decline in the percentage conversion of CO. The amount of solid carbon deposited on a given bimetallic catalyst was shown

  12. Hydrogen-Stimulated Carbon Acquisition and Conservation in Salmonella enterica Serovar Typhimurium ? §

    PubMed Central

    Lamichhane-Khadka, Reena; Frye, Jonathan G.; Porwollik, Steffen; McClelland, Michael; Maier, Robert J.

    2011-01-01

    Salmonella enterica serovar Typhimurium can utilize molecular hydrogen for growth and amino acid transport during anaerobic growth. Via microarray we identified H2 gas-affected gene expression changes in Salmonella. The addition of H2 caused altered expression of 597 genes, of which 176 genes were upregulated and 421 were downregulated. The significantly H2-upregulated genes include those that encode proteins involved in the transport of iron, manganese, amino acids, nucleosides, and sugars. Genes encoding isocitrate lyase (aceA) and malate synthase (aceB), both involved in the carbon conserving glyoxylate pathway, and genes encoding the enzymes of the d-glucarate and d-glycerate pathways (gudT, gudD, garR, garL, garK) are significantly upregulated by H2. Cells grown with H2 showed markedly increased AceA enzyme activity compared to cells without H2. Mutant strains with deletion of either aceA or aceB had reduced H2-dependent growth rates. Genes encoding the glutamine-specific transporters (glnH, glnP, glnQ) were upregulated by H2, and cells grown with H2 showed increased [14C]glutamine uptake. Similarly, the mannose uptake system genes (manX, manY) were upregulated by H2, and cells grown with H2 showed about 2.0-fold-increased [14C]d-mannose uptake compared to the cells grown without H2. Hydrogen stimulates the expression of genes involved in nutrient and carbon acquisition and carbon-conserving pathways, linking carbon and energy metabolism to sustain H2-dependent growth. PMID:21856852

  13. Structural and electronic properties of electron cyclotron resonance plasma deposited hydrogenated amorphous carbon and carbon nitride films

    NASA Astrophysics Data System (ADS)

    Godet, C.; Conway, N. M. J.; Bourée, J. E.; Bouamra, K.; Grosman, A.; Ortega, C.

    2002-04-01

    Hydrogenated amorphous carbon and carbon nitride films (a-C1-xNx:H) have been synthesized from methane, acetylene, or acetylene-nitrogen precursor gases using a high density electron cyclotron resonance plasma. The deposition and etching rates, along with the film stoichiometry, density, Raman signature of the sp2 phase, and optical and transport properties, have been studied as a function of plasma parameters (microwave power and negative bias of the substrate). While low-density H-rich carbon films have been grown from methane for ion energies up to 200 eV, films grown using acetylene have been obtained at high deposition rate (1.1 nm s-1) with H content below 25 H at. % and density of 2.0 g cm-3, which makes them interesting as electronic materials. For dense carbon nitride alloys, the maximum (N/N+C)=0.35 is limited by the vanishing growth rate, which results from ion-assisted chemical etching mechanisms. A larger N2 plasma etching rate related with lower film density is observed for (N/N+C) values above 0.20. As a function of the N content, Raman spectra give evidence of a continuous structural ordering of the sp2 phase, which is confirmed by a modeling of the ohmic conductivity ?(T) data based on hopping transport within a bandtail distribution of localized ? states. With increasing N content, a better overlap of p orbitals along with an increase in the localization length are expected as a consequence of a less constrained environment. A maximum of the room-temperature conductivity at (N/N+C)=0.28 reveals the onset of a transition towards polymeric alloys with lower mean coordination number.

  14. Structural influence of ordered mesoporous carbon supports for the hydrogenation of carbon monoxide to alcohols.

    PubMed

    Kim, Min-Ji; Chae, Ho-Jeong; Ha, Kyoung Su; Jeong, Kwang-Eun; Kim, Chul-Ung; Jeong, Soon-Yong; Kim, Tae-Wan

    2013-11-01

    A series of ordered mesoporous carbon materials (OMCs) possessing well-ordered nanoporosity with different mesopore structures were synthesized by the template-synthesis route. Two different pore strucutes (2-dimensional hexagonal and 3-dimensional cubic structures) and two different framework-configurations (rod-type and hollow-type carbon frameworks) are prepared by using the two different silica templates and synthetic conditions. The ordered mesoporous carbon supported promoted-rhodium catalysts were preparted by an incipient wetness method. The promoted Rh-OMC catalysts are tested by a fixed bed reactor for the catalytic conversion of syngas-to-alcohols. The characteristics of the promoted Rh-OMCs catalysts were scrutinized through a series of different techniques, including transmission electron microscopy (TEM), powder X-ray diffraction (XRD), and N2 sorption analysis, and the catalytic performance was tested in a fixed-bed reactor. It was found that the promoted Rh-OMC catalysts exhibited the different catalytic activity and selectivity of alcohols, which could be attributed to the size of metal nanoparticles being confined by the different mesostructure of OMCs. PMID:24245283

  15. Synthesis of carbon-iron(II) oxide layer on the surface of magnetite and its reactivity with H2O for hydrogen generation

    Microsoft Academic Search

    Y. Tamaura; K. Akanuma; N. Hasegawa; M. Tsuji

    1994-01-01

    Synthesis of a carbon-iron(II) oxide layer on the surface of magnetite and its reactivity with H2O for hydrogen generation reaction have been studied. X-ray diffractometry and chemical analysis showed that the carbon-bearing magnetite synthesized by the carbon-deposition reaction from CO2 gas with the hydrogen-reduced magnetite, was magnetite with a carbon-iron(II) oxide layer (CIO layer-M; M is stoichiometric magnetite) represented by

  16. Reorganization of graphite surfaces into carbon micro- and nanoparticles under high flux hydrogen plasma bombardment

    SciTech Connect

    Bystrov, Kirill; Vegt, Lenze van der; De Temmerman, Gregory; Arnas, Cecile; Marot, Laurent [FOM Institute DIFFER-Dutch Institute for Fundamental Energy Research, Association EURATOM-FOM, Partner in the Trilateral Euregio Cluster, P.O. Box 1207, NL-3430 BE Nieuwegein (Netherlands); Laboratoire de Physique des Interactions Ioniques et Moleculaires (PIIM), CNRS/Aix-Marseille Universite, F-13397 Marseille (France); Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland)

    2013-01-15

    Fine-grain graphite samples were exposed to high density low temperature (n{sub e}{approx}10{sup 20} m{sup -3}, T{sub e}{approx}1 eV) hydrogen plasmas in the Pilot-PSI linear plasma generator. Redeposition of eroded carbon is so strong that no external precursor gas injection is necessary for deposits to form on the exposed surface during the bombardment. In fact, up to 90% of carbon is redeposited, most noticeably in the region of the highest particle flux. The redeposits appear in the form of carbon microparticles of various sizes and structures. Discharge parameters influence the efficiency of the redeposition processes and the particle growth rate. Under favorable conditions, the growth rate reaches 0.15 {mu}m/s. The authors used high resolution scanning electron microscopy and transmission electron microscopy to study the particle growth mode. The columnar structure of some of the large particles points toward surface growth, while observation of the spherical carbon nanoparticles indicates growth in the plasma phase. Multiple nanoparticles can agglomerate and form bigger particles. The spherical shape of the agglomerates suggests that nanoparticles coalesce in the gas phase. The erosion and redeposition patterns on the samples are likely determined by the gradients in plasma flux density and surface temperature across the surface.

  17. Activation of extended red emission photoluminescence in carbon solids by exposure to atomic hydrogen and UV radiation

    NASA Technical Reports Server (NTRS)

    Furton, Douglas G.; Witt, Adolf N.

    1993-01-01

    We report on new laboratory results which relate directly to the observation of strongly enhanced extended red emission (ERE) by interstellar dust in H2 photodissociation zones. The ERE has been attributed to photoluminescence by hydrogenated amorphous carbon (HAC). We are demonstrating that exposure to thermally dissociated atomic hydrogen will restore the photoluminescence efficiency of previously annealed HAC. Also, pure amorphous carbon (AC), not previously photoluminescent, can be induced to photoluminesce by exposure to atomic hydrogen. This conversion of AC into HAC is greatly enhanced by the presence of UV irradiation. The presence of dense, warm atomic hydrogen and a strong UV radiation field are characteristic environmental properties of H2 dissociation zones. Our results lend strong support to the HAC photoluminescence explanation for ERE.

  18. Carbon nanotubes for hydrogen storage as being studied by the National Renewable Energy Laboratory. Technical evaluation report

    SciTech Connect

    Skolnik, E.G. [Energetics, Inc., Columbia, MD (United States)

    1997-08-01

    On June 17--18, the author met with Dr. Mike Heben of the National Renewable Energy Laboratory (NREL) to discuss his research on the development of carbon nanotubes to be used for the storage of hydrogen on-board a vehicle. Dr. Heben has been working for the past several years on a project that will develop single walled nanotubes (SWNTs) composed of carbon for storage of hydrogen. Dr. Heben has spent much time trying to develop a method by which he could produce SWNTs in sufficient quantity, and then demonstrate the adsorption and desorption of hydrogen from these nanotubes at room temperature. While Dr. Heben was able to show hydrogen adsorption levels of up to 10% on a SWNT basis, generation of SWNTs from an arc-discharge was only about 0.05% of the total soot formation. Therefore, increasing SWNT concentration was a key consideration. Findings from the meeting with Dr. Heben are presented.

  19. Method for converting hydrocarbon fuel into hydrogen gas and carbon dioxide

    DOEpatents

    Clawson, Lawrence G. (Dover, MA); Mitchell, William L. (Belmont, MA); Bentley, Jeffrey M. (Westford, MA); Thijssen, Johannes H. J. (Cambridge, MA)

    2000-01-01

    A method for converting hydrocarbon fuel into hydrogen gas and carbon dioxide within a reformer 10 is disclosed. According to the method, a stream including an oxygen-containing gas is directed adjacent to a first vessel 18 and the oxygen-containing gas is heated. A stream including unburned fuel is introduced into the oxygen-containing gas stream to form a mixture including oxygen-containing gas and fuel. The mixture of oxygen-containing gas and unburned fuel is directed tangentially into a partial oxidation reaction zone 24 within the first vessel 18. The mixture of oxygen-containing gas and fuel is further directed through the partial oxidation reaction zone 24 to produce a heated reformate stream including hydrogen gas and carbon monoxide. Steam may also be mixed with the oxygen-containing gas and fuel, and the reformate stream from the partial oxidation reaction zone 24 directed into a steam reforming zone 26. High- and low-temperature shift reaction zones 64,76 may be employed for further fuel processing.

  20. Synthesis of aliphatic hydrocarbons from carbon monoxide and hydrogen on Co-Ca alumina catalysts

    SciTech Connect

    Lapidus, A.L.; Bruk, I.A.; Yakerson, V.I.; Mamayeva, I.L.; Golosman, Ye.Z.

    1980-01-01

    The selection of carriers is of considerable importance for developing high-activity catalysts for the synthesis of aliphatic hydrocarbons from carbon monoxide and hydrogen. Natural diatomites - kieselguhrs used at the present time in industry for these purposes are characterized by the dependence of chemical composition and physical-chemical properties on the occurrence and depth of the diatomite layer. Furthermore, a general shortcoming of this type of carrier is the low mechanical strength of catalysts based on them, involving considerable loss of catalysts in handling and loading reactors. Reported is a catalyst system based on high-strength calcium aluminates containing cobalt and various intermediate additives as active components. It was established that this system was active in the synthesis of aliphatic hydrocarbons from carbon monoxide and hydrogen. A study of the effect of MgO contents in Catalysts on properties showed that catalysts containing 2.5 parts by weight MgO had the highest activity. The yield of liquid hydrocarbons reached 102.4 g/nm/sup 3/ at 220/sup 0/C. (JMT)