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1

Water, hydrogen, deuterium, carbon, carbon-13, and oxygen-18 content of selected lunar material  

USGS Publications Warehouse

The water content of the breccia is 150 to 455 ppm, with a ??D from -580 to -870 per mil. Hydrogen gas content is 40 to 53 ppm with a ??D of -830 to -970 per mil. The CO2 is 290 to 418 ppm with S 13C = + 2.3 to + 5.1 per mil and ??18O = 14.2 to 19.1 per mil. Non-CO2 carbon is 22 to 100 ppm, ??18C = -6.4 to -23.2 per mil. Lunar dust is 810 ppm H2O (D = 80 ppm) and 188 ppm total carbon (??13C = -17.6 per mil). The 18O analyses of whole rocks range from 5.8 to 6.2 per mil. The temperature of crystallization of type B rocks is 1100?? to 1300??C, based on the oxygen isotope fractionation between coexisting plagioclase and ilmenite.

Friedman, I.; O'Neil, J.R.; Adami, L.H.; Gleason, J.D.; Hardcastle, K.

1970-01-01

2

Water, hydrogen, deuterium, carbon, carbon-13, and oxygen-18 content of selected lunar material.  

PubMed

The water content of the breccia is 150 to 455 ppm, with a deltaD from-580 to -870 per mil. Hydrogen gas content is 40 to 53 ppm with a deltaD of -830 to -970 per mil. The CO(2) is 290 to 418 ppm with delta (13)C = + 2.3 to + 5.1 per mil and delta(18)O = 14.2 to 19.1 per mil. Non-CO(2) carbon is 22 to 100 ppm, delta(13)C = -6.4 to -23.2 per mil. Lunar dust is 810 ppm H(2)O (D = 80 ppm) and 188 ppm total carbon(delta(13)C = -17.6 per mil). The (18)O analyses of whole rocks range from 5.8 to 6.2 per mil. The temperature of crystallization of type B rocks is 1100 degrees to 1300 degrees C, based on the oxygen isotope fractionation between coexisting plagioclase and ilmenite. PMID:17781488

Friedman, I; O'neil, J R; Adami, L H; Gleason, J D; Hardcastle, K

1970-01-30

3

Vibrational circular dichroism in the carbon-hydrogen and carbon-deuterium stretching modes of (S,S)-(2,3-²Hâ)oxirane  

Microsoft Academic Search

The authors report vibrational circular dichroism (VCD) spectra of (S,S)-(2,3-²Hâ)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

Teresa B. Freedman; M. Germana Paterlini; Nam Soo Lee; Laurence A. Nafie; John M. Schwab; Tapan Ray

1987-01-01

4

The Hydrogen-Deuterium Exchange at ?-Carbon Atom in N,N,N-Trialkylglycine Residue: ESI-MS Studies  

NASA Astrophysics Data System (ADS)

Derivatization of peptides as quaternary ammonium salts (QAS) is a known method for sensitive detection by electrospray ionization tandem mass spectrometry. Hydrogens at ?-carbon atom in N, N, N-trialkylglycine residue can be easily exchanged by deuterons. The exchange reaction is base-catalyzed and is dramatically slow at lower pH. Introduced deuterons are stable in acidic aqueous solution and are not back-exchanged during LC-MS analysis. Increased ionization efficiency, provided by the fixed positive charge on QAS group, as well as the deuterium labeling, enables the analysis of trace amounts of peptides.

Rudowska, Magdalena; Wojewska, Dominika; Kluczyk, Alicja; B?chor, Remigiusz; Stefanowicz, Piotr; Szewczuk, Zbigniew

2012-06-01

5

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

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.

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

1987-07-22

6

Energy Levels of Hydrogen and Deuterium  

National Institute of Standards and Technology Data Gateway

SRD 142 Energy Levels of Hydrogen and Deuterium (Web, free access)   This database provides theoretical values of energy levels of hydrogen and deuterium for principle quantum numbers n = 1 to 200 and all allowed orbital angular momenta l and total angular momenta j. The values are based on current knowledge of the revelant theoretical contributions including relativistic, quantum electrodynamic, recoil, and nuclear size effects.

7

Deuterium inventory in Tore Supra: Coupled carbon-deuterium balance  

NASA Astrophysics Data System (ADS)

This paper presents an analysis of the carbon-deuterium circulation and the resulting balance in Tore Supra over the period 2002-2007. Carbon balance combines the estimation of carbon gross erosion from spectroscopy, net erosion and deposition using confocal microscopy, lock-in thermography and SEM, and a measure of the amount of deposits collected in the vacuum chamber. Fuel retention is determined from post-mortem (PM) analyses and gas balance (GB) measurements. Special attention was paid to the deuterium outgassed during the nights and weekends of the experimental campaign (vessel under vacuum, Plasma Facing Components at 120 °C) and during vents (vessel at atmospheric pressure, PFCs at room temperature). It is shown that this outgassing is the main process reconciling the PM and GB estimations of fuel retention, closing the coupled carbon-deuterium balance. In particular, it explains why the deuterium concentration in deposits decreases with increasing depth.

Pégourié, B.; Panayotis, S.; Languille, P.; Martin, C.; Dittmar, T.; Gauthier, E.; Hatchressian, J.-C.; Pascal, J.-Y.; Roubin, P.; Ruffe, R.; Tsitrone, E.; Vartanian, S.; Wang, H.; Beauté, A.; Bouvet, J.; Brosset, C.; Bucalossi, J.; Cabié, M.; Caprin, E.; Courtois, X.; Dachicourt, R.; Delchambre, E.; Dominici, C.; Douai, D.; Ekedahl, A.; Gunn, J. P.; Hakola, A.; Jacob, W.; Khodja, H.; Likonen, J.; Linez, F.; Litnovsky, A.; Marandet, Y.; Markelj, S.; Martinez, A.; Mayer, M.; Meyer, O.; Monier-Garbet, P.; Moreau, P.; Negrier, V.; Oddon, P.; Pardanaud, C.; Pasquet, B.; Pelicon, P.; Petersson, P.; Philipps, V.; Possnert, G.; Reiter, D.; Roth, J.; Roure, I.; Rubel, M.; Saint-Laurent, F.; Samaille, F.; Vavpeti?, P.

2013-07-01

8

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

NASA Astrophysics Data System (ADS)

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.

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

2005-08-01

9

The deuterium content of atmospheric molecular hydrogen  

Microsoft Academic Search

A new technique for the separation of molecular hydrogen (H2) from air and the determination of its deuterium (D) content is presented. A high-pressure air sample in an aluminum cylinder is condensed at -196°C, whereby H2 contained in the air sample is enriched in the gaseous headspace above the liquefied air. The H2-enriched headspace is bled into a vacuum extraction

Steven Gregory Gerst

2000-01-01

10

Temperature dependent deuterium quadrupole coupling constants of short hydrogen bonds  

E-print Network

Temperature dependent deuterium quadrupole coupling constants of short hydrogen bonds Xingang Zhao January 2006 Abstract Very short hydrogen bonds universally show large positive dependences and intermode couplings. q 2006 Published by Elsevier B.V. Keywords: Hydrogen bonds; NMR; Deuterium quadrupole 1

Barsegov, Valeri

11

Omegatron mass spectrometer in a hydrogen/deuterium detached plasma  

SciTech Connect

Diagnostics of the relative concentrations of the atomic and molecular ions were carried out in hydrogen/deuterium plasma with hydrogen/deuterium gas puff in the linear plasma device, TPD-SheetIV. An omegatron ion mass spectrometer is used for analyzing ion species.

Tonegawa, A.; Nishijima, T.; Ishioka, H.; Nakanowatari, A.; Kawamura, K. [Department of Physics, School of Science, Tokai University, Kitakaname 1117, Hiratsuka 259-1292 (Japan)

2008-03-12

12

Deuterium retention of ferritic steel irradiated by energetic hydrogen ions  

NASA Astrophysics Data System (ADS)

Ferritic steel (F82H) was irradiated by energetic hydrogen ions to make a irradiation damage. The damaged ferritic steel was irradiated by deuterium ions with energy of 1.7 keV in order to investigate the retention and desorption behavior of deuterium. The deuterium ion fluence was taken up to 5 × 10 18 D/cm 2. The amount of retained deuterium increased as the deuterium ion fluence and saturated at 1 × 10 18 D/cm 2. It was clearly seen that the amount of retained deuterium increased as the damage caused by the hydrogen ion irradiation. For example, the amount of retained deuterium in the sample with 4 dpa was several times larger than that in the sample without damage. It was also seen that the desorption temperature approximately 70 K increased compared with that without damage. These results suggest that the number of trapping site and trapping energy for fuel hydrogen increases owing to the irradiation damage. The present results show that both fuel hydrogen recycling and in-vessel tritium inventory increases by the irradiation damage.

Hino, T.; Katada, Y.; Yamauchi, Y.; Akiba, M.; Suzuki, S.; Ezato, T.

2009-04-01

13

Si-SiO2 Interface Passivation Using Hydrogen and Deuterium Implantation  

E-print Network

/HfO2 interface2 after the hydrogen/ deuterium H/D isotope effect was discovered.3 Deuterium passivaSi-SiO2 Interface Passivation Using Hydrogen and Deuterium Implantation T. Kundu and D. Misraz 07102, USA Hydrogen/deuterium was implanted in 100 silicon to passivate dangling bonds at the Si/SiO2

Misra, Durgamadhab "Durga"

14

Diffusion of muonic deuterium and hydrogen atoms  

SciTech Connect

Diffusion of muonic deuterium {mu}d and muonic hydrogen {mu}p atoms produced following the stopping of negative muons in D{sub 2} or H{sub 2} at 300 K was studied at pressures of 47{endash}750 mbar (H{sub 2}) and 94{endash}1520 mbar (D{sub 2}) in two distinct target geometries. Time intervals were recorded between entry of negative muons into the gas and arrival of each resulting {mu}d or {mu}p atom at one of 50 foils immersed in the gas, and spaced regularly along the muon beam axis. The results of such measurements were fitted to time distributions generated by Monte Carlo methods, using theoretical scattering predictions and empirically chosen forms for the initial energy distributions of the muonic atoms in the 1S state. Results indicate muonic atom energy distributions which (a) are different for {mu}d and {mu}p and (b) vary with pressure. The best-fit energy distributions have mean energies ranging from 1.5 eV for {mu}d at 94 mbar to {ge}9 eV for {mu}p at 750 mbar. The data are also sensitive to scattering cross sections for {mu}d and {mu}p, and are consistent with current theoretical calculations for the {mu}d+D{sub 2} cross sections. In the case of {mu}p+H{sub 2} scattering, the experimental data suggest discrepancies with the theoretical predictions. {copyright} {ital 1997} {ital The American Physical Society}

Abbott, D.J.; Chen, G.F.; Guss, P.; Hancock, A.D.; Kraiman, J.B.; Siegel, R.T.; Vulcan, W.F.; Viel, D.W.; Welsh, R.E. [College of William and Mary in Virginia, Williamsburg, Virginia 23185 (United States)] [College of William and Mary in Virginia, Williamsburg, Virginia 23185 (United States); Petitjean, C.; Zehnder, A. [Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland)] [Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland); Breunlich, W.H.; Cargnelli, M.; Kammel, P.; Scrinzi, A.; Marton, J.; Zmeskal, J. [Institut fuer Mittelenergiephysik, Oesterreichische Akademie der Wissenschaften, A-1090 Vienna (Austria)] [Institut fuer Mittelenergiephysik, Oesterreichische Akademie der Wissenschaften, A-1090 Vienna (Austria); Reidy, J.J.; Woolverton, H.L. [University of Mississippi, University, Mississippi 38667 (United States)] [University of Mississippi, University, Mississippi 38667 (United States); Hartmann, F.J. [Technische Universitaet Muenchen, D-85748 Garching (Germany)] [Technische Universitaet Muenchen, D-85748 Garching (Germany); Adamczak, A. [Institute for Nuclear Physics, PL-31-342 Cracow (Poland)] [Institute for Nuclear Physics, PL-31-342 Cracow (Poland); Markushin, V.E. [Russian Scientific Center, Kurchatov Institute, RU-123182 Moscow (Russia)] [Russian Scientific Center, Kurchatov Institute, RU-123182 Moscow (Russia); Melezhik, V.S. [Joint Institute for Nuclear Research, RU-141980 Dubna (Russia)] [Joint Institute for Nuclear Research, RU-141980 Dubna (Russia)

1997-01-01

15

The deuterium content of atmospheric molecular hydrogen  

NASA Astrophysics Data System (ADS)

A new technique for the separation of molecular hydrogen (H2) from air and the determination of its deuterium (D) content is presented. A high-pressure air sample in an aluminum cylinder is condensed at -196°C, whereby H2 contained in the air sample is enriched in the gaseous headspace above the liquefied air. The H2-enriched headspace is bled into a vacuum extraction line where the H2 is oxidized to H2O for cryogenic isolation from the air stream. The captured water is reduced back to H2 for determination of its D/H ratio via isotope-ratio mass spectrometry (?D is reported in permil (‰) vs. Vienna Standard Mean Ocean Water, where ?D = ((D/H)sample/(D/H) VSMOW - 1)*1000‰). Air samples for ?D analyses were collected in November-December 1998 on a transect from Seattle, WA, 48°N, to McMurdo, Antarctica, 71°S (n = 19), and over a two-year interval on the Washington Coast, 48°N (n = 11), and Point Barrow, AK, 71°N (n = 6). Results indicate that the average ?D of global atmospheric H2 is +130 +/- 4‰, with average ?D values of +123 +/- 3‰ and +138 +/- 8‰ in the northern and southern hemispheres, respectively. Comparison of background and polluted samples in the Seattle area indicate the ?D of H2 produced by anthropogenic activities (e.g. automobiles) is -1961 +/- 10‰. Laboratory combustion studies of pine needles and pine branches indicate that the ?D of H2 emitted during biomass burning is -293 +/- 60‰. The results of field experiments (n = 6) using a large chamber to isolate a volume of air in contact with soil imply that the H2 removed during soil uptake has a ?D value 57 +/- 24‰ lower than that of atmospheric H2. The constraints that these preliminary isotopic measurements place on the global H2 budget are limited by the unmeasured isotopic composition of photochemically produced H2, ?Dh?. However, the global H2 isotope balance implies that the average global value of ?Dh? must be +130‰, and this value is demonstrated to be plausible. Therefore, it is concluded that the available isotopic measurements are not in disagreement with the global H2 budget, as had been previously suggested.

Gerst, Steven Gregory

2000-09-01

16

Ordered ground states of metallic hydrogen and deuterium  

NASA Technical Reports Server (NTRS)

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.

Ashcroft, N. W.

1981-01-01

17

Nucleus polarizability contribution to the hydrogen-deuterium isotope shift  

E-print Network

The correction to the hydrogen-deuterium isotope shift due to the proton and deuteron polarizability is evaluated on the basis of modern experimental data on the structure functions of inelastic lepton-nucleus scattering. The numerical value of this contribution is equal 63\\pm 12 Hz.

R. N. Faustov; A. P. Martynenko

2001-08-10

18

Appendix A SIMS profiles of hydrogen and deuterium in diamond  

E-print Network

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

Goddard III, William A.

19

Laser-driven polarized sources of hydrogen and deuterium  

SciTech Connect

A novel laser-driven polarized source of hydrogen and deuterium which operates on the principle of spin exchange optical pumping is described. The advantages of this method over conventional polarized sources for internal target experiments are presented. Technological difficulties which prevent ideal source operation are outlined along with proposed solutions. At present, the laser-driven polarized hydrogen source delivers 8 /times/ 10/sup 16/ atoms/s with a polarization (P/sub z/) of 24%. 9 refs., 2 figs.

Young, L.; Holt, R.J.; Green, M.C.; Kowalczyk, R.S.

1988-01-01

20

The pion nucleon scattering lengths from pionic hydrogen and deuterium  

NASA Astrophysics Data System (ADS)

This is the final publication of the ETH Zurich Neuchâtel PSI collaboration on the pionic hydrogen and deuterium precision X-ray experiments. We describe the recent hydrogen 3 p 1 s measurement, report on the determination of the Doppler effect correction to the transition line width, analyze the deuterium shift measurement and discuss implications of the combined hydrogen and deuterium results. From the pionic hydrogen 3 p 1 s transition experiments we obtain the strong-interaction energy level shift \\varepsilon_{1s} = -7.108±0.013 (stat.)±0.034 (syst.) eV and the total decay width ?_{1s} = 0.868±0.040 (stat.)±0.038 (syst.) eV of the 1s state. Taking into account the electromagnetic corrections we find the hadronic ? N s-wave scattering amplitude a_{?-prightarrow?-p} = 0.0883±0.0008 m_{?}^{-1} for elastic scattering and a_{?-prightarrow?0n} = -0.128±0.006 m_{?} ^{-1} for single charge exchange, respectively. We then combine the pionic hydrogen results with the 1 s level shift measurement on pionic deuterium and test isospin symmetry of the strong interaction: our data are still compatible with isospin symmetry. The isoscalar and isovector ? N scattering lengths (within the framework of isospin symmetry) are found to be b_0 = -0.0001^{+0.0009}_{-0.0021} m_{?}^{-1} and b1 = -0.0885^{+0.0010}_{-0.0021} m_{?} ^{-1}, respectively. Using the GMO sum rule, we obtain from b_1 a new value of the ? N coupling constant (g_{? N} = 13.21_{-0.05}^{+0.11}) from which follows the Goldberger Treiman discrepancy ?_{{GT}} =0.027_{-0.008}^{+0.012}. The new values of b_0 and g_{? N} imply an increase of the nucleon sigma term by at least 9 MeV.

Schröder, H.-Ch.; Badertscher, A.; Goudsmit, P. F. A.; Janousch, M.; Leisi, H. J.; Matsinos, E.; Sigg, D.; Zhao, Z. G.; Chatellard, D.; Egger, J.-P.; Gabathuler, K.; Hauser, P.; Simons, L. M.; Rusi El Hassani, A. J.

2001-07-01

21

Equations of state for hydrogen and deuterium.  

SciTech Connect

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.

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

2003-12-01

22

Theory of muonic hydrogen - muonic deuterium isotope shift  

E-print Network

We calculate the corrections of orders alpha^3, alpha^4 and alpha^5 to the Lamb shift of the 1S and 2S energy levels of muonic hydrogen (mu p) and muonic deuterium (mu d). The nuclear structure effects are taken into account in terms of the proton r_p and deuteron r_d charge radii for the one-photon interaction and by means of the proton and deuteron electromagnetic form factors in the case of one-loop amplitudes. The obtained numerical value of the isotope shift (mu d) - (mu p) for the splitting (1S-2S) 101003.3495 meV can be considered as a reliable estimation for corresponding experiment with the accuracy 10^{-6}. The fine structure interval E(1S)-8E(2S) in muonic hydrogen and muonic deuterium are calculated.

A. P. Martynenko

2004-12-17

23

Lifetimes of Hydrogen and Deuterium Related Vibrational Modes in Silicon  

SciTech Connect

Lifetimes of hydrogen and deuterium related stretch modes in Si are measured by high-resolution infrared absorption spectroscopy and transient bleaching spectroscopy. The lifetimes are found to be extremely dependent on the defect structure, ranging from 2 to 295 ps. Against conventional wisdom, we find that lifetimes of Si-D modes typically are longer than for the corresponding Si-H modes. The potential implications of the results on the physics of electronic device degradation are discussed.

Budde, M.; Luepke, G.; Chen, E; Zhang, X.; Tolk, N. H.; Feldman, L. C.; Tarhan, E.; Ramdas, A. K.; Stavola, M.

2001-10-01

24

Reactivity of TiO 2 with hydrogen and deuterium  

NASA Astrophysics Data System (ADS)

The reactivity of rutile phase TiO 2 (1 1 0) and polycrystalline anatase surfaces with molecular and ionized deuterium and hydrogen was investigated. Thermal Desorption Spectroscopy (TDS), following exposure to more than 100 kL of molecular deuterium, showed a D 2 desorption peak at ˜440 K on both single crystal rutile and polycrystalline anatase surfaces. The desorption peak was observed following exposure only at surface temperatures between 140-270 K. Ionized D 2 is significantly more reactive with the titania surface and two desorption peaks at 380 K and ˜550 K were observed together with a small D 2O peak observed at ˜440 K. Dosing the surfaces with hydrogen and deuterium either in succession or as a mixture showed HD desorption with no change in the desorption peaks, consistent with dissociative adsorption of both ionized and molecular species. The experimental data was compared to Density Functional Theory calculations and modeled as a two-step process of hydrogen dissociation at oxygen vacancy sites on TiO 2.

Yang, Y.; Sushchikh, M.; Mills, G.; Metiu, H.; McFarland, E.

2004-05-01

25

HYDROGEN AND DEUTERIUM NMR OF SOLIDS BY MAGIC ANGLE SPINNING  

SciTech Connect

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.

Eckman, R.R.

1982-10-01

26

Measurement of the ratio of hydrogen to deuterium at the KSTAR 2009 experimental campaign  

SciTech Connect

The control of the ratio of hydrogen to the deuterium is one of the very important issues for ion cyclotron range of frequency (ICRF) minority heating as well as the plasma wall interaction in the tokamak. The ratio of hydrogen to deuterium during the tokamak shot was deduced from the emission spectroscopy measurements during the KSTAR 2009 experimental campaign. Graphite tiles were used for the plasma facing components (PFCs) at KSTAR and its surface area exposed to the plasma was about 11 m{sup 2}. The data showed that it remained as high as around 50% during the campaign period because graphite tiles were exposed to the air for about two months and the hydrogen contents at the tiles are not fully pumped out due to the lack of baking on the PFC in the 2009 campaign. The validation of the spectroscopy method was checked by using the Zeeman effects and the ratio of hydrogen to the deuterium is compared with results from the residual gas analysis. During the tokamak shot, the ratio is low below 10% initially and saturated after around 1 s. When there is a hydrogen injection to the vessel via ion cyclotron wall conditioning and the boronization process where the carbone is used, the ratio of the hydrogen to the deuterium is increased by up to 100% and it recovers to around 50% after one day of operation. However it does not decrease below 50% at the end of the experimental campaign. It was found that the full baking on the PFC (with a high temperature and sufficient vacuum pumping) is required for the ratio control which guarantees the efficient ICRF heating at the KSTAR 2010 experimental campaign.

Kwak, Jong-Gu; Wang, Son Jong; Kim, Sun Ho [Korea Atomic Energy Research Institute, 1045 Daedeok-daero, Yuseong, Daejeon, South Korea, 305-353 (Korea, Republic of); Park, Jae Min; Na, Hoon Kyun [National Fusion Research Institute, Yuseong, Daejeon, South Korea, 305-333 (Korea, Republic of)

2010-10-15

27

Excited state muon transfer in hydrogen/deuterium mixtures  

SciTech Connect

We report the first direct observation of excited state muon transfer in hydrogen/deuterium mixtures by direct measurement of {ital q}{sub 1{ital s}}, the probability that a {mu}{ital p} atom, which is initially formed in an excited state, reaches the 1{ital s} ground state. The dependence of {ital q}{sub 1{ital s}} on deuterium concentration {ital c}{sub {ital d}} was measured for two different densities at cryogenic temperatures using charge coupled devices to detect the muonic x rays. First results based on the analysis of the {ital K}{sub {alpha}} lines of the two isotopes are presented. {copyright} {ital 1996 The American Physical Society.}

Lauss, B.; Ackerbauer, P.; Breunlich, W.H.; Gartner, B.; Jeitler, M.; Kammel, P.; Marton, J.; Prymas, W.; Zmeskal, J. [Institute for Medium Energy Physics, Austrian Academy of Sciences, Boltzmanngasse 3, A-1090 Wien (Austria)] [Institute for Medium Energy Physics, Austrian Academy of Sciences, Boltzmanngasse 3, A-1090 Wien (Austria); Chatellard, D.; Egger, J.; Jeannet, E. [Institut de Physique de l`Universite, CH-2000 Neuchatel (Switzerland)] [Institut de Physique de l`Universite, CH-2000 Neuchatel (Switzerland); Daniel, H.; Kosak, A.; Hartmann, F.J. [Physik Department, TU Muenchen, D-85748 Garching (Germany)] [Physik Department, TU Muenchen, D-85748 Garching (Germany); Petitjean, C. [Paul Scherrer Institut, CH-5232 Villigen (Switzerland)] [Paul Scherrer Institut, CH-5232 Villigen (Switzerland)

1996-06-01

28

Diffusion of hydrogen and deuterium in Zr-Al  

SciTech Connect

Optimization of getter performance necessitates a detailed understanding of the getter operation for a variety of experimental parameters, including pressure, temperature, getter mass, and getter thickness. For pumping at low pressures or during slow desorption, the getter operation will be dependent primarily on surface kinetics, which have been described previously. During pumping at higher pressures or during rapid desorption, bulk diffusion may play an important role. In this paper we present the first measurements of the diffusivities of hydrogen (D/sub H/) and deuterium (D/sub D/) in Zr-Al as determined from detailed analysis of desorption.

Knize, R.J.; Cecchi, J.L.

1982-10-01

29

Experimental results of hydrogen distillation at the low power cryogenic column for the production of deuterium depleted hydrogen  

SciTech Connect

The Deuterium Removal Unit (DRU) has been designed and built at the Petersburg Nuclear Physics Inst. (PNPI) to produce isotopically pure hydrogen with deuterium content less than 1 ppm. The cryogenic distillation column of 2.2 cm inner diameter and 155 cm packing height is the main element of the DRU. Column performances at different hydrogen distillation operating modes have been measured. The height equivalent to theoretical plate (HETP) for the column is 2.2 cm and almost constant over a wide range of vapour flow rates. Deuterium depleted hydrogen with a deuterium content of less than 0.1 ppm was produced in required quantity. (authors)

Alekseev, I.; Fedorchenko, O.; Kravtsov, P.; Vasilyev, A.; Vznuzdaev, M. [Petersburg Nuclear Physics Inst., Leningrad district, Gatchina, 188300 (Russian Federation)

2008-07-15

30

The Vapor Pressures and Derived Thermal Properties of Hydrogen and Deuterium  

Microsoft Academic Search

(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

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

1934-01-01

31

Influence of carbon concentration on chemical behavior of energetic deuterium implanted into carbon-contained boron film  

NASA Astrophysics Data System (ADS)

Influence of carbon concentration on chemical behavior of energetic deuterium implanted into carbon-contained boron film was investigated by XPS and TDS. Total deuterium retention and the retention of deuterium trapped by boron were decreased as the carbon concentration was increased, although that by carbon was increased. 60% of the total deuterium retention was trapped by carbon for the sample at the carbon concentration of around 30%, suggesting that deuterium had more affinity with carbon than boron. Above the carbon concentration of 20%, the chemical states of carbon were clearly changed, which led to the deuterium trapping by carbon, indicating the chemical structure change would make a large influence on D trapping. It can be said that deuterium trapped by carbon should be taken into consideration for the evaluation of tritium inventory in the carbon-contained boron film with the carbon concentration above 20%.

Suzuki, Sachiko; Yang, Yu; Yoshikawa, Akira; Kikuchi, Yohei; Sagara, Akio; Oya, Yasuhisa; Okuno, Kenji

2009-06-01

32

Hydrogen/deuterium exchange in interstellar ice analogs  

NASA Astrophysics Data System (ADS)

Context: For several reasons, methanol is believed to be formed on grain surfaces and, in warm environments, released in the gas phase. In the past, multiply deuterated isotopologues of methanol have been detected in gas phase around several low-mass protostars. In all these sources, there is significantly more CH2DOH than CH3OD. Various hypotheses have been suggested to explain this anomaly, but none is fully convincing. Aims: In this work, we test a new hypothesis experimentally: the spontaneous exchange between hydrogen and deuterium atoms in water ice as responsible for the deficiency of CH3OD with respect to CH2DOH. Methods: We follow the temperature dependence of the composition of interstellar ice analogs initially composed of CD3OD and H2O. To this aim, thin films of intimate H2O:CD3OD ice mixtures, condensed at low temperature (<110 K), are monitored by Fourier transform infrared (FTIR) spectroscopy up to the complete evaporation of CD3OD (~170 K). Results: Rapid hydrogen/deuterium (H/D) exchange is observed, at 120 K and above, through the growth of the ?_OD stretching mode of HDO at ~2425 cm-1. It is also shown that H/D exchange occurs i) on the hydroxyl functional group of methanol, i.e through hydrogen bonds, and ii) before the completion of crystallization. Conclusions: The present results suggest that the much lower abundance of CH3OD compared to CH2DOH in low-mass protostars could reflect H/D exchanges in water ice either prior to or definitely during the grain mantle sublimation. This solid-state depletion mechanism, so far neglected in the astronomical literature, might affect other deuterated molecules with hydrogen bonds.

Ratajczak, A.; Quirico, E.; Faure, A.; Schmitt, B.; Ceccarelli, C.

2009-03-01

33

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

Microsoft Academic Search

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

1981-01-01

34

CATALYTIC EXCHANGE OF HYDROGEN SULPHIDE AND OF HYDROGEN WITH DEUTERIUM ON DISULPHIDES OF MOLYBDENUM AND TUNGSTEN  

Microsoft Academic Search

The exchange reaction between hydrogen sulfide and deuterium was ; followed in the temperature range l50 to 200 deg C on a molybdenum disulfide ; catalyst and in the range 40 to 100 deg C on a sample of tungsten disulfide, the ; latter having a substantially greater surface area than the former. Studies were ; also made on the

R. L. Wilson; C. Kemball; A. K. Galwey

1962-01-01

35

Toward standardizing deuterium content reporting in hydrogen exchange-MS.  

PubMed

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

Sheff, Joey G; Schriemer, David C

2014-12-16

36

Carbon balance and deuterium inventory from a carbon dominated to a full tungsten ASDEX Upgrade  

NASA Astrophysics Data System (ADS)

The evolution of carbon/boron deposition and the deuterium inventory were determined during the transition from a carbon dominated to a full tungsten ASDEX Upgrade. In the carbon dominated machine about 17 g of carbon were deposited at the inner divertor and in remote areas during one standard discharge campaign. Main carbon sources were the ICRH antennae protection limiters in the main chamber. After coating these limiters with tungsten the carbon deposition decreased to 3-5 g. The remaining carbon originated mainly from erosion at the outer divertor strike point. Transition to a full tungsten machine resulted in a further decrease of the carbon deposition to about 1 g. 1.3-1.7 g deuterium was trapped in codeposited carbon/boron layers in the divertor and in remote areas during the carbon dominated campaigns. The deuterium inventory decreased to 0.16-0.24 g in the full tungsten machine.

Mayer, M.; Rohde, V.; Sugiyama, K.; Chen, J. L.; Gong, X.; Hopf, C.; Likonen, J.; Lindig, S.; Neu, R.; Ramos, G.; Vainonen-Ahlgren, E.; Wiltner, A.; ASDEX Upgrade Team

2009-06-01

37

Amorphous Hydrogenated Carbon Nanofilm  

Microsoft Academic Search

Amorphous hydrogenated carbon (a-C:H) nanofilm is a metastable form of amorphous carbon with significant sp3 bonding. a-C:H\\u000a is a semiconductor with a high mechanical hardness, chemical inertness, and optical transparency. This chapter will describe\\u000a the deposition methods, deposition mechanisms, characterization methods, electronic structure, gap states, defects, doping,\\u000a luminescence, field emission, mechanical properties, and some applications of a-C:H. The films have

Dechun Ba; Zeng Lin

38

Probing protein ensemble rigidity and hydrogen-deuterium exchange  

NASA Astrophysics Data System (ADS)

Protein rigidity and flexibility can be analyzed accurately and efficiently using the program floppy inclusion and rigid substructure topography (FIRST). Previous studies using FIRST were designed to analyze the rigidity and flexibility of proteins using a single static (snapshot) structure. It is however well known that proteins can undergo spontaneous sub-molecular unfolding and refolding, or conformational dynamics, even under conditions that strongly favor a well-defined native structure. These (local) unfolding events result in a large number of conformers that differ from each other very slightly. In this context, proteins are better represented as a thermodynamic ensemble of ‘native-like’ structures, and not just as a single static low-energy structure. Working with this notion, we introduce a novel FIRST-based approach for predicting rigidity/flexibility of the protein ensemble by (i) averaging the hydrogen bonding strengths from the entire ensemble and (ii) by refining the mathematical model of hydrogen bonds. Furthermore, we combine our FIRST-ensemble rigidity predictions with the ensemble solvent accessibility data of the backbone amides and propose a novel computational method which uses both rigidity and solvent accessibility for predicting hydrogen-deuterium exchange (HDX). To validate our predictions, we report a novel site specific HDX experiment which characterizes the native structural ensemble of Acylphosphatase from hyperthermophile Sulfolobus solfataricus (Sso AcP). The sub-structural conformational dynamics that is observed by HDX data, is closely matched with the FIRST-ensemble rigidity predictions, which could not be attained using the traditional single ‘snapshot’ rigidity analysis. Moreover, the computational predictions of regions that are protected from HDX and those that undergo exchange are in very good agreement with the experimental HDX profile of Sso AcP.

Sljoka, Adnan; Wilson, Derek

2013-10-01

39

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

E-print Network

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 ...

Antoniewicz, Maciek R.

40

HYDROGEN DISTILLATION AT THE DEUTERIUM REMOVAL UNIT OF MuCap EXPERIMENT  

E-print Network

321 HYDROGEN DISTILLATION AT THE DEUTERIUM REMOVAL UNIT OF MuCap EXPERIMENT I.A. Alekseev, E hydrogen gas (so- called protium) must be used. It is necessary to avoid transfers of - to impurities imposes strict and critical requirements on the hydrogen gas system supporting the detector. Desirable

Titov, Anatoly

41

Precise Calculation of Transition Frequencies of Hydrogen and Deuterium Based on a Least-Squares Analysis  

SciTech Connect

We combine a limited number of accurately measured transition frequencies in hydrogen and deuterium, recent quantum electrodynamics (QED) calculations, and, as an essential additional ingredient, a generalized least-squares analysis, to obtain precise and optimal predictions for hydrogen and deuterium transition frequencies. Some of the predicted transition frequencies have relative uncertainties more than an order of magnitude smaller than that of the g factor of the electron, which was previously the most accurate prediction of QED.

Jentschura, Ulrich D. [National Institute of Standards and Technology, Mail Stop 8401, Gaithersburg, Maryland 20899-8401 (United States); Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); Kotochigova, Svetlana; Mohr, Peter J.; Taylor, Barry N. [National Institute of Standards and Technology, Mail Stop 8401, Gaithersburg, Maryland 20899-8401 (United States); Le Bigot, Eric-Olivier [National Institute of Standards and Technology, Mail Stop 8401, Gaithersburg, Maryland 20899-8401 (United States); Laboratoire Kastler Brossel, Ecole Normale Superieure et Universite Pierre et Marie Curie, Case 74, 4 place Jussieu, 75005 Paris (France)

2005-10-14

42

Hydrogen, Deuterium and Tritium in Palladium: An Elastic Constants Study  

SciTech Connect

We have used resonant ultrasound spectroscopy to measure the three independent elastic constants of Pd-H, Pd-D, and Pd-T single crystal at 300K as a function of hydrogen, deuterium, and tritium concentration, respectively. The addition of interstitial H (D, or T) atoms, located at (0,1/2,0) in the fcc Pd lattice, affects all three elastic constants C', C{sub 44}, and B. In the mixed ({alpha}+{beta}) phase, and with increasing H isotope, the shear modulus C' shows an abnormal softening whereas C{sub 44} and B do not. This is explained in terms of Zener-type an elastic relaxations affecting the shape of the hydride phases in the coherent({alpha}+{beta}) two-phase mixture In the single {beta}-phase, C' shows a strong isotope dependence whereas C{sub 44} and B show none. This behavior is explained in terms of differences in the excitation of optical phonons. In Pd-T, {sup 3}He is produced by the radioactive decay of tritium. We have measured in situ the swelling and the change in the elastic constants in Pd-T as a function of aging time. Aging ({sup 3}He formation) affects all three elastic constants. These measurements are being used to understand the early stages of {sup 3}H-{sup 3}He cluster formation in aged Pd-T crystal.

Bach, H.T.; Schwarz, R.B.; Tuggle, D.G. [Los Alamos National Laboratory (United States)

2005-07-15

43

ELECTRON CYCLOTRON RESONANCE DISCHARGE AS A SOURCE FOR HYDROGEN AND DEUTERIUM IONS PRODUCTION  

E-print Network

1 ELECTRON CYCLOTRON RESONANCE DISCHARGE AS A SOURCE FOR HYDROGEN AND DEUTERIUM IONS PRODUCTION@uis.edu.co In this report, we describe characteristics of a ring-structure hydrogen plasma heated in electron cyclotron are observed in an electron cyclotron resonance (ECR) plasma source, #12;2 with the reaction channel involving

Boyer, Edmond

44

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

Microsoft Academic Search

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

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

1984-01-01

45

Precision Measurement of the Hydrogen-Deuterium 1S-2S Isotope Shift  

NASA Astrophysics Data System (ADS)

Measuring the hydrogen-deuterium isotope shift via two-photon spectroscopy of the 1S-2S transition, we obtain 670 994 334 606(15) Hz. This is a 10-times improvement over the previous best measurement [A. Huber , Phys. Rev. Lett. 80, 468 (1998)PRLTAO0031-900710.1103/PhysRevLett.80.468] confirming its frequency value. A calculation of the difference of the mean square charge radii of deuterium and hydrogen results in ?r2?d-?r2?p=3.82007(65)fm2, a more than twofold improvement compared to the former value.

Parthey, Christian G.; Matveev, Arthur; Alnis, Janis; Pohl, Randolf; Udem, Thomas; Jentschura, Ulrich D.; Kolachevsky, Nikolai; Hänsch, Theodor W.

2010-06-01

46

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

SciTech Connect

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.

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

47

Hydrogen storage by carbon sorption  

Microsoft Academic Search

This research determined experimentally the extent to which carbon sorbents such as activated carbon, carbon black, carbon aerogels, and carbon molecular sieves can augment the capacity of compressed hydrogen gas (CHG) storage systems. These carbon sorbents were tested at ambient temperature (300 K), at acetone-and-dry-ice temperature (190 K), and at liquid-nitrogen temperature (80 K). We concluded that, at the pressures

Scott Hynek; Ware Fuller; Jeffrey Bentley

1997-01-01

48

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

NASA Technical Reports Server (NTRS)

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.

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

1975-01-01

49

Calculated fractionation factors for carbon and hydrogen isotope exchange in the system calcite-carbon dioxide-graphite-methane-hydrogen-water vapor  

Microsoft Academic Search

Isotopic fractionation factors have been calculated for deuterium exchange between hydrogen, water vapor and methane, and for carbon-13 exchange between graphite, calcite, carbon dioxide and methane. These fractionation factors have been tabulated at various intervals between 0 and 700°C. Some geochemical applications of the calculated data are discussed

Y. Bottinga

1969-01-01

50

Hydrogen storage in carbon nanostructures  

Microsoft Academic Search

Carbon nanotubes have been known for more than 10 years. It is a challenge to fill their unique tubular structure with metals and gases. Especially, the absorption of hydrogen in single wall nanotubes has attracted many research groups worldwide. The values published for the quantity of hydrogen absorbed in nanostructured carbon materials varies between 0.4 and 67 mass%. With the

A. Züttel; P. Sudan; Ph. Mauron; T. Kiyobayashi; Ch. Emmenegger; L. Schlapbach

2002-01-01

51

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

PubMed

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

Nagy, Kornél; Redeuil, Karine; Rezzi, Serge

2009-11-15

52

Deuterium inventory in Tore Supra: Contribution of carbon deposits outgassing  

NASA Astrophysics Data System (ADS)

In carbon dominated devices, the in vessel D inventory obtained from post-mortem analyses of plasma facing component samples is generally smaller by a factor of ˜4 than that estimated from gas balance measurements. However, for an accurate evaluation of the wall inventory, gas balance measurements must be done not only during discharges and conditioning procedures, but also in between discharges and during vents. From the analysis of the whole Tore Supra database for the 2002-2007 period, we show that long term outgassing during nights, weekends and vents is essential for evaluating the deuterium release. Taking these contributions into account reconciles the gas balance and post-mortem estimations of fuel retention.

Panayotis, S.; Pégourié, B.; Caprin, E.; Douai, D.; Hatchressian, J.-C.; Negrier, V.; Pascal, J.-Y.; Vartanian, S.; Bucalossi, J.; Monier-Garbet, P.

2013-07-01

53

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

PubMed Central

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

Niemeyer, Emily D.; Brodbelt, Jennifer S.

2007-01-01

54

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

NASA Technical Reports Server (NTRS)

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.

Mauk, S. C.

1980-01-01

55

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...

56

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

ERIC Educational Resources Information Center

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…

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

2014-01-01

57

Radiative Correction to the Nuclear-Size Effect and Hydrogen-Deuterium Isotopic Shift  

E-print Network

The radiative correction to the nuclear charge radius contribution to the Lamb shift of order $\\alpha(Z\\alpha)^5m_r^3$ is calculated. In view of the recent high precision experimental data, this theoretical correction produces a significant contribution to the hydrogen-deuterium isotopic shift.

Michael I. Eides; Howard Grotch

1997-09-19

58

Advantages of Isotopic Depletion of Proteins for Hydrogen/Deuterium Exchange Experiments Monitored by Mass Spectrometry  

E-print Network

Advantages of Isotopic Depletion of Proteins for Hydrogen/Deuterium Exchange Experiments Monitored, the peaks overlap and the spectra become more and more crowded because of the presence of heavier isotopes.0 667.0 Isotopic depletion (i.e. elimination of heavier isotopes) reduces the complexity of the spectra

59

THE REACTION RATE OF HYDROGEN AND DEUTERIUM AS MEASURED IN A CHEMICAL QUENCH TUBE  

Microsoft Academic Search

Reprinted from thesis dated June 1962. A chemical quench tube was built ; and instrumented in such a way that the reaction rate of hydrogen and deuterium ; (Hâ + Dâ in equilibrium 2 HD) could be measured. The main ; innovation was the use of a solenoid-actuated valve to isolate the reacting gas ; and prevent it from mixing

1962-01-01

60

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

NASA Astrophysics Data System (ADS)

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.

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

2015-03-01

61

Empirical corrections for anharmonic zero-point vibrations of hydrogen and deuterium in geometric hydrogen bond correlations  

Microsoft Academic Search

In this paper, empirical corrections for anharmonic ground-state vibrations of hydrogen and deuterium in the hydrogen bridges A–L?B, L=H, D are introduced into the geometric hydrogen bond correlation analysis based on the empirical Pauling valence bond orders. The method is verified using the examples of the hydrogen bonded anions in [(CO)5Cr–C?N?H?N?C–Cr(CO)5]? As(Ph)4+ (1h), in [(CO)5Cr–C?N?H?N?C–Cr(CO)5]? N(n-propyl)4+ (2h), in the model

Hans-Heinrich Limbach; Mariusz Pietrzak; Hans Benedict; Peter M. Tolstoy; Nikolai S. Golubev; Gleb S. Denisov

2004-01-01

62

Relaxation Process Due to Long-Range Diffusion of Hydrogen and Deuterium in Niobium  

Microsoft Academic Search

We have applied a new method for the determination of diffusion coefficients to hydrogen and deuterium in niobium. The activation energies for both isotopes are comparatively small and differ by about 20%, whereas D0 is the same within experimental error. The activation energy for hydrogen diffusion is equal to the energy difference ℏomegaH=114+\\/-6 meV between the ground state and the

G. Schaumann; J. Voelkl; G. Alefeld

1968-01-01

63

Hydrogen and deuterium in Pd25 pct Ag alloy: Permeation, diffusion, solubilization, and surface reaction  

Microsoft Academic Search

In this work, the hydrogen and deuterium transport parameters such as permeability, diffusivity, and solubility in a Pd-25\\u000a pct Ag alloy are studied, using a permeation gas phase technique and, additionally, a computer-controlled microbalance system.\\u000a In the region in which Sieverts' law is valid, the hydrogen solubilities found using both techniques are in very good agreement.\\u000a From permeation measurements, the

E. Serra; M. Kemali; A. Perujo; D. K. Ross

1998-01-01

64

Isotope effects in dense solid hydrogen - Phase transition in deuterium at 190 + or - 20 GPa  

NASA Technical Reports Server (NTRS)

Raman measurements of solid normal deuterium compressed in a diamond-anvil cell indicate that the material undergoes a structural phase transformation at 190 + or - 20 GPa and 77 K. Spectroscopically, the transition appears analogous to that observed in hydrogen at 145 + or - 5 GPa. The large isotope effect on the transition pressure suggests there is a significant vibrational contribution to the relative stability of the solid phases of hydrogen at very high densities.

Hemley, R. J.; Mao, H. K.

1989-01-01

65

Continuous-flow isotope analysis of the deuterium/hydrogen ratio in atmospheric hydrogen.  

PubMed

A convenient method is described for analyzing the deuterium/hydrogen (D/H) ratio of atmospheric molecular hydrogen (H(2)) based on mass spectrometric isotope-ratio monitoring. The method requires small amounts of air ( approximately 300 mL STP), is operated on-line, and comprises four steps: (1). the condensation of the air matrix at approximately 40 K; (2). the collection of the non-condensed components of the air sample (H(2), Ne, He, and traces of N(2)) in a 5 A molecular sieves pre-concentration trap at approximately 63 K; (3). gas chromatographic purification of H(2) in a flow of He; and (4) quantification of the D/H ratio in an isotope-ratio mass spectrometer. The precision of the determination of the D/H ratio is better than 2 per thousand, which is comparable to, or better than, that obtained by conventional duel-inlet off-line analysis. There are, however, discrepancies relative to the D/H ratios determined by conventional duel-inlet analysis. This is due to differences in peak shape between reference and sample air, depending on the amount of H(2) injected. Consequently, calibration runs are required. After the calibration of the system, we obtained an accuracy of 1.5 per thousand, so that the accumulated uncertainty is estimated to be less than 4 per thousand. The method also allows determination of the H(2) concentration, with an uncertainty estimated to be 2%. PMID:14755615

Rhee, Tae Siek; Mak, John; Röckmann, Thomas; Brenninkmeijer, Carl A M

2004-01-01

66

Functionalization of Carbon Nanotubes using Atomic Hydrogen  

NASA Technical Reports Server (NTRS)

We have investigated the irradiation of multi walled and single walled carbon nanotubes (SWNTs) with atomic hydrogen. After irradiating the SWNT sample, a band at 2940/cm (3.4 microns) that is characteristic of the C-H stretching mode is observed using Fourier transform infrared (FTIR) spectroscopy. Additional confirmation of SWNT functionalization is tested by irradiating with atomic deuterium. A weak band in the region 1940/cm (5.2 micron) to 2450/cm (4.1 micron) corresponding to C-D stretching mode is also observed in the FTIR spectrum. This technique provides a clean gas phase process for the functionalization of SWNTs, which could lead to further chemical manipulation and/or the tuning of the electronic properties of SWNTs for nanodevice applications.

Khare, Bishun N.; Cassell, Alan M.; Nguyen, Cattien V.; Meyyappan, M.; Han, Jie; Arnold, Jim (Technical Monitor)

2001-01-01

67

Hydrogen storage in carbon nanostructures  

Microsoft Academic Search

The paper gives a critical review of the literature on hydrogen storage in carbon nanostructures. Furthermore, the hydrogen storage of graphite, graphite nanofibers (GNFs), and single-walled carbon nanotubes (SWNTs) was measured by thermal desorption spectroscopy (TDS). The samples were ball milled under Ar or D2 atmosphere in order to modify the microstructure which was characterized by X-ray diffraction, scanning electron

M Hirscher; M Becher; M Haluska; A Quintel; V Skakalova; Y.-M Choi; U Dettlaff-Weglikowska; S Roth; I Stepanek; P Bernier; A Leonhardt; J Fink

2002-01-01

68

Hydrogen/deuterium exchange mass spectrometry applied to IL-23 interaction characteristics: potential impact for therapeutics.  

PubMed

IL-23 is an important therapeutic target for the treatment of inflammatory diseases. Adnectins are targeted protein therapeutics that are derived from domain III of human fibronectin and have a similar protein scaffold to antibodies. Adnectin 2 was found to bind to IL-23 and compete with the IL-23/IL-23R interaction, posing a potential protein therapeutic. Hydrogen/deuterium exchange mass spectrometry and computational methods were applied to probe the binding interactions between IL-23 and Adnectin 2 and to determine the correlation between the two orthogonal methods. This review summarizes the current structural knowledge about IL-23 and focuses on the applicability of hydrogen/deuterium exchange mass spectrometry to investigate the higher order structure of proteins, which plays an important role in the discovery of new and improved biotherapeutics. PMID:25711416

Iacob, Roxana E; Krystek, Stanley R; Huang, Richard Y-C; Wei, Hui; Tao, Li; Lin, Zheng; Morin, Paul E; Doyle, Michael L; Tymiak, Adrienne A; Engen, John R; Chen, Guodong

2015-04-01

69

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

SciTech Connect

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.

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

70

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

Microsoft Academic Search

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

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

2010-01-01

71

New Precision Studies of Strong Interaction in Exotic Atoms: Kaonic Hydrogen and Deuterium  

SciTech Connect

The DEAR experiment at LNF delivered the most precise data on kaonic hydrogen up to now and triggered new theoretical studies. DEAR and its follow-up experiment SIDDHARTA are using precision X-ray spectroscopy of kaonic hydrogen and kaonic deuterium atoms to measure the strong interaction induced shift and width of the ground state. From these observables the isospin-dependent antikaon-nucleon scattering lengths can be determined, thus contributing to the understanding of aspects of chiral symmetry breaking in the strangeness sector.

Marton, Johann [Stefan Meyer Institut (SMI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna (Austria)

2006-11-17

72

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

PubMed

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

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

2014-06-20

73

Hydrogen storage in carbon nanotubes  

Microsoft Academic Search

Hydrogen storage in new nano-structured carbonic materials is a topic for lively discussion. The measured storage capacities of these materials, which have been announced in the literature during the last ten years are spread over an enormous range from about 0.1 wt% up to 67 wt%. This paper will give a report on the state of the art of hydrogen storage in

M. Becher; M. Haluska; M. Hirscher; A. Quintel; V. Skakalova; U. Dettlaff-Weglikovska; X. Chen; M. Hulman; YJ Choi; S. Roth; V. Meregalli; M. Parrinello; R. Ströbel; L. Jörissen; M. M. Kappes; J. Fink; A. Züttel; I. Stepanek; P. Bernier

2003-01-01

74

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

SciTech Connect

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.

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

75

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

NASA Astrophysics Data System (ADS)

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 PuH2). The heats of solution for PuHS and PuDS 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.

Richmond, S.; Bridgewater, J. S.; Ward, J. W.; Allen, T. H.

2010-03-01

76

Kinetic Method for Hydrogen-Deuterium-Tritium Mixture Distillation Simulation  

SciTech Connect

Simulation of hydrogen distillation plants requires mathematical procedures suitable for multicomponent systems. In most of the present-day simulation methods a distillation column is assumed to be composed of theoretical stages, or plates. However, in the case of a multicomponent mixture theoretical plate does not exist.An alternative kinetic method of simulation is depicted in the work. According to this method a system of mass-transfer differential equations is solved numerically. Mass-transfer coefficients are estimated with using experimental results and empirical equations.Developed method allows calculating the steady state of a distillation column as well as its any non-steady state when initial conditions are given. The results for steady states are compared with ones obtained via Thiele-Geddes theoretical stage technique and the necessity of using kinetic method is demonstrated. Examples of a column startup period and periodic distillation simulations are shown as well.

Sazonov, A.B.; Kagramanov, Z.G.; Magomedbekov, E.P. [Mendeleyev University of Chemical Technology of Russia (Russian Federation)

2005-07-15

77

Hydrogenation of single-walled carbon nanotubes  

E-print Network

Towards the development of a useful mechanism for hydrogen storage, we have studied the hydrogenation of single-walled carbon nanotubes with atomic hydrogen using core-level photoelectron spectroscopy and x-ray absorption spectroscopy. We find that atomic hydrogen creates C-H bonds with the carbon atoms in the nanotube walls and such C-H bonds can be com-pletely broken by heating to 600 oC. We demonstrate approximately 65+/-15 at % hydrogenation of carbon atoms in the single-walled carbon nanotubes which is equivalent to 5.1+/-1.2 weight % hydrogen capacity. We also show that the hydrogenation is a reversible process.

Anton Nikitin; Hirohito Ogasawara; David Mann; Reinhard Denecke; Zhiyong Zhang; Hongjie Dai; KJ Cho; Anders Nilsson

2005-10-14

78

state. However, the rates of hydrogen/deuterium exchange demonstrate that the conformation of human PrPC is not  

E-print Network

state. However, the rates of hydrogen/deuterium exchange demonstrate that the conformation of human, and can be Structural mobility of the human prion protein probed by backbone hydrogen exchange Laszlo L. P8 1TD, UK.4Krebs Institute for Biomolecular Research, Dept. of Molecular Biology and Biotechnology

Hosszu, Laszlo

79

Difference in Fibril Core Stability between Two Tau Four-Repeat Domain Proteins: A Hydrogen-Deuterium Exchange Coupled to  

E-print Network

Difference in Fibril Core Stability between Two Tau Four-Repeat Domain Proteins: A Hydrogen for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560 065, India *S Supporting hydrogen-deuterium exchange coupled to mass spectrometry as a tool. While the two fibrils are found

80

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

PubMed Central

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

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

2014-01-01

81

Experimental investigations of electron capture from atomic hydrogen and deuterium by alpha particles  

SciTech Connect

We report progress made during the period 15 September 1991--14 September 1992 on the project Experimental Investigations of Electron Capture from Atomic Hydrogen and Deuterium by Alpha Particles''. In the past year we have developed reliable, narrow energy spread, high-current sources of He[sup ++] based on direct-current magentron and electron-cyclotron resonance discharges. These sources have been proven on our test bench accelerator which has been upgraded to also allow us to test atomic hydrogen effusive targets. We have thus made substantial progress toward our goal of studying single electron capture from atomic hydrogen by doubly-ionized helium. A research plan for the upcoming year is also presented.

Gay, T.J.; Park, J.T.

1992-01-01

82

Analysis of oligomeric stability of insulin analogs using hydrogen/deuterium exchange mass spectrometry.  

PubMed

Insulin analog products for subcutaneous injection are prepared as solutions in which insulin analog molecules exist in several oligomeric states. Oligomeric stability can affect their onset and duration of action and has been exploited in designing them. To investigate the oligomeric stability of insulin analog products having different pharmacokinetics, we performed hydrogen/deuterium exchange mass spectrometry (HDX/MS), which is a rapid method to analyze dynamic aspects of protein structures. Two rapid-acting analogs (lispro and glulisine) incorporated deuteriums more and faster than recombinant human insulin, whereas a long-acting analog (glargine) and two intermediate-acting preparations (protamine-containing formulations) incorporated them less and more slowly. Kinetic analysis revealed that the number of slowly exchanged hydrogens (D(s)) (k<0.01 min(-1)) accounted for the difference in HDX reactivity among analogs. Furthermore, we found correlations between HDX kinetics and pharmacokinetics reported previously. Their maximum serum concentration (C(max)) was linearly correlated with D(s) (r=0.88) and the number of maximum exchangeable hydrogens (D(?)) (r=0.89). The maximum drug concentration time (t(max)) was also correlated with reciprocals of D(s) and D(?) (r=0.86 and r=0.96, respectively). Here we demonstrate the ability of HDX/MS to evaluate oligomeric stability of insulin analog products. PMID:21951784

Nakazawa, Shiori; Hashii, Noritaka; Harazono, Akira; Kawasaki, Nana

2012-01-01

83

Anomalously deep penetration of hydrogen and deuterium in assemblies from Nb foils and deuterated polyethylene (CD2) n under the pulse high temperature hydrogen plasma  

NASA Astrophysics Data System (ADS)

Studies of the storage and redistribution of hydrogen atoms under pulse high temperature hydrogen plasma that was obtained using a PF-4 Plasma Focus facility in a multilayered structure (sandwich) which consists of two high-purity niobium foils and a deuterium polyethylene film pressed between them have been carried out using the method for elastic recoil detection (ERD). It was established that, with an increase in pulses of the PF-4 facility, the redistribution of implanted hydrogen atoms for large depths occurs in the two Nb foils and deuterated polyethylene. The depths substantially exceed the projective range of paths of hydrogen ions (at their maximum velocity of ˜108 cm/s). A maximum hydrogen concentration of 45 at % is reached in the nearest surface of the second Nb foil to the PF-4 at 20 pulses of hydrogen plasma. An X-ray diffraction analysis showed the presence of a niobium hydride phase in both Nb foils. The redistribution of deuterium atoms from the bound state of deuterated polyethylene into the near-surface layer and the bulk material of the second Nb foil was detected as well. This phenomenon can be attributed to the transfer of implanted hydrogen atoms through the foil assembly and the transfer of deuterium from deuterated polyethylene into the near-surface layer of the second foil under the effect of powerful shock waves that are created by pulse hydrogen plasma and by acceleration in the diffusion of hydrogen and deuterium in the strain field induced by the shock wave.

Didyk, A. Yu.

2012-03-01

84

NMR-Based Detection of Hydrogen/Deuterium Exchange in Liposome-Embedded Membrane Proteins  

PubMed Central

Membrane proteins play key roles in biology. Determination of their structure in a membrane environment, however, is highly challenging. To address this challenge, we developed an approach that couples hydrogen/deuterium exchange of membrane proteins to rapid unfolding and detection by solution-state NMR spectroscopy. We show that the method allows analysis of the solvent protection of single residues in liposome-embedded proteins such as the 349-residue Tom40, the major protein translocation pore in the outer mitochondrial membrane, which has resisted structural analysis for many years. PMID:25375235

Yao, Xuejun; Dürr, Ulrich H. N.; Gattin, Zrinka; Laukat, Yvonne; Narayanan, Rhagavendran L.; Brückner, Ann-Kathrin; Meisinger, Chris; Lange, Adam; Becker, Stefan; Zweckstetter, Markus

2014-01-01

85

Determination of hydrogen/deuterium ratio with neutron measurements on MAST  

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

86

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

PubMed

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

Hone, Tyler D; Voth, Gregory A

2004-10-01

87

Studies of negative ions by collision-induced decomposition and hydrogen-deuterium exchange techniques.  

PubMed

Development of two new techniques for studying the gas phase chemistry of negative ions is reported. Collision induced dissociation (CID) of (M-1)- ions has been accomplished in a newly constructed triple stage quadrupole mass spectrometer. This instrument was assembled by adding two additional Finnigan quadrupole mass filters to a Finnigan Model 3200 CI mass spectrometer. Generation of (M-1)- ions is accomplished by allowing OH- and sample to react under CI conditions in the ion source. The first quadrupole mass filter, Q1, is then employed to selectively pass the (M-1)- ion into a second quadrupole filter containing argon or neon at 10(-3) torr. On collision with the inert gas the (M-1)- ions dissociate into fragments which are then mass analyzed in the third quadrupole filter, CID spectra of (M-1)- ions from twelve carbonyl compounds are presented in this paper. Ion molecule isotope exchange reactions in the CI ion source can be used to count the number of hydrogen atoms in many different chemical environments. Collisions between sample (M-1)- ions and deuterium-labeled reagent gases (ND3, D2O, EtOD) facilitate incorporation of deuterium into the negative ion if the basicities of the sample and reagent anions are similar. Thus it is possible to selectively incorporate deuterium into many organic samples by controlling the exothermicity of the acid base, ion-molecule chemistry. PMID:7428745

Hunt, D F; Sethi, S K; Shabanowitz, J

1980-06-01

88

Studies of negative ions by collision-induced decomposition and hydrogen-deuterium exchange techniques.  

PubMed Central

Development of two new techniques for studying the gas phase chemistry of negative ions is reported. Collision induced dissociation (CID) of (M-1)- ions has been accomplished in a newly constructed triple stage quadrupole mass spectrometer. This instrument was assembled by adding two additional Finnigan quadrupole mass filters to a Finnigan Model 3200 CI mass spectrometer. Generation of (M-1)- ions is accomplished by allowing OH- and sample to react under CI conditions in the ion source. The first quadrupole mass filter, Q1, is then employed to selectively pass the (M-1)- ion into a second quadrupole filter containing argon or neon at 10(-3) torr. On collision with the inert gas the (M-1)- ions dissociate into fragments which are then mass analyzed in the third quadrupole filter, CID spectra of (M-1)- ions from twelve carbonyl compounds are presented in this paper. Ion molecule isotope exchange reactions in the CI ion source can be used to count the number of hydrogen atoms in many different chemical environments. Collisions between sample (M-1)- ions and deuterium-labeled reagent gases (ND3, D2O, EtOD) facilitate incorporation of deuterium into the negative ion if the basicities of the sample and reagent anions are similar. Thus it is possible to selectively incorporate deuterium into many organic samples by controlling the exothermicity of the acid base, ion-molecule chemistry. PMID:7428745

Hunt, D F; Sethi, S K; Shabanowitz, J

1980-01-01

89

Analysis of Overlapped and Noisy Hydrogen/Deuterium Exchange Mass Spectra  

NASA Astrophysics Data System (ADS)

Noisy and overlapped mass spectrometry data hinder the sequence coverage that can be obtained from hydrogen deuterium exchange analysis, and places a limit on the complexity of the samples that can be studied by this technique. Advances in instrumentation have addressed these limits, but as the complexity of the biological samples under investigation increases, these problems are re-encountered. Here we describe the use of binomial distribution fitting with asymmetric linear squares regression for calculating the accurate deuterium content for mass envelopes of low signal or that contain significant overlap. The approach is demonstrated with a test data set of HIV Env gp140 wherein inclusion of the new analysis regime resulted in obtaining exchange data for 42 additional peptides, improving the sequence coverage by 11 %. At the same time, the precision of deuterium uptake measurements was improved for nearly every peptide examined. The improved processing algorithms also provide an efficient method for deconvolution of bimodal mass envelopes and EX1 kinetic signatures. All these functions and visualization tools have been implemented in the new version of the freely available software, HX-Express v2.

Guttman, Miklos; Weis, David D.; Engen, John R.; Lee, Kelly K.

2013-12-01

90

Measurements of atomic recombination in the HERMES polarized hydrogen and deuterium storage cell target  

NASA Astrophysics Data System (ADS)

The use of storage cells has become a standard technique for internal gas targets in storage rings. In case of polarized hydrogen or deuterium targets, recombination of the atoms occurs during the collisions of the atoms with the walls of the storage cell and may lead to a reduction of the target polarization. In this paper, we present measurements of recombination at the polarized internal hydrogen and deuterium gas target of the HERMES experiment in the years 1997-1999 within a temperature range of 35- 250 K. The underlying reaction mechanisms will be discussed with respect to the measured temperature and gas density dependence of surface recombination. Special attention is paid to the influence of water on recombination. These dependencies can be consistently described by a combination of three reaction mechanisms. The first one, dominating at temperatures above 120 K, is an activated Eley-Rideal reaction. A second process dominating below 100 K in case of new storage cells, is interpreted as a tunneling reaction between a physisorbed state and an atom chemically bound on the surface. When the storage cell coating is aged by the influence of the HERA positron beam, the second process is suppressed and a third (weaker) process starts to dominate. This third mechanism is described by Langmuir-Hinshelwood type reactions between physisorbed atoms.

Baumgarten, C.; Braun, B.; Court, G.; Ciullo, G.; Dalpiaz, P. F.; Golendukhin, A.; Graw, G.; Haeberli, W.; Henoch, M.; Hertenberger, R.; Koch, N.; Kolster, H.; Lenisa, P.; Nass, A.; Pod'yachev, S. P.; Reggiani, D.; Rith, K.; Steffens, E.; Stewart, J.; Wise, T.

2003-01-01

91

Probing Conserved Helical Modules of Portal Complexes by Mass Spectrometry based Hydrogen/deuterium Exchange  

PubMed Central

The dsDNA bacteriophage P22 has a ring shaped dodecameric complex composed of the 84 kDa portal protein subunit which forms the central channel of the phage’s DNA packaging motor. The overall morphology of the P22 portal complex is similar to that of the portal complexes of Phi29, SPP1, T3, T7 phages and herpes simplex virus. Secondary structure prediction of P22 portal protein and its threading onto the crystal structure of the Phi29 portal complexes suggested that P22 portal protein complex shares conserved helical modules which were found in the dodecameric interfaces of the Phi29 portal complex. To identify the amino acids involved in inter-subunit contacts in the P22 portal ring complexes and validate the threading model, we performed comparative hydrogen/deuterium exchange analysis of monomeric and in vitro assembled portal proteins of P22 and the dodecameric Phi29 portal. Hydrogen/deuterium exchange experiments provided evidence of inter-subunit interactions in the P22 portal complex similar to those in the Phi29 portal which map to the regions predicted to be conserved helical modules. PMID:18621389

Kang, Sebyung; Poliakov, Anton; Sexton, Jennifer; Renfrow, Matthew B.; Prevelige, Peter E.

2008-01-01

92

An atomic beam polarimeter to measure the nuclear polarization in the HERMES gaseous polarized hydrogen and deuterium target  

NASA Astrophysics Data System (ADS)

An atomic beam polarimeter for measurement of the hyperfine population numbers and the absolute polarization of thermal atomic hydrogen (H) and deuterium (D) beams is described. The principle of measurement and the method of calibration are given. The polarimeter measures the 4 (6) relative hyperfine population numbers of a thermal H (D) beam in the region of 10 13 atoms s -1 to an absolute error of less than 0.01. The polarimeter has been in continuous operation with the internal polarized hydrogen and deuterium gas target used in the HERMES experiment at DESY since 1996.

Baumgarten, C.; Braun, B.; Court, G.; Ciullo, G.; Ferretti, P.; Golendukhin, A.; Graw, G.; Haeberli, W.; Henoch, M.; Hertenberger, R.; Koch, N.; Kolster, H.; Lenisa, P.; Nass, A.; Pod'yachev, S. P.; Reggiani, D.; Rith, K.; Simani, M. C.; Steffens, E.; Stewart, J.; Wise, T.

2002-04-01

93

Isotopic effect study in the LHCD and LHH experiments in hydrogen/deuterium plasmas of the FT-2 tokamak  

SciTech Connect

Results of comparative experimental studies of the efficiency of lower hybrid current drive (LHCD) and lower hybrid heating (LHH) in the FT-2 tokamak in hydrogen and deuterium plasmas are presented. In the new comparative experimental runs in deuterium/hydrogen plasmas suppression of the LHCD and beginning of the interaction of LH waves with ions is controlled by the plasma density rise. Role of parametric instabilities in CD switch-off is considered. In order to analyze the experimentally observed effect of LHCD the GRILL3D and FRTC codes has been used.

Lashkul, S. I.; Altukhov, A. B.; Gusakov, E. Z.; Dyachenko, V. V.; Esipov, L. A.; Irzak, M. A.; Kantor, M. Yu.; Kouprienko, D. V.; Saveliev, A. N. [A. F. Ioffe Physical-Technical Institute, Politekhnicheskaya 26, 194021, St. Petersburg (Russian Federation); Shatalin, S. V. [St. Petersburg State Polytekhnical University, St. Petersburg (Russian Federation); Stepanov, A. Yu. [A.F. Ioffe Physical-Technical Institute, Politekhnicheskaya 26, 194021, St. Petersburg (Russian Federation)

2014-02-12

94

Catalytic hydrogenation of carbon monoxide  

SciTech Connect

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.

Wayland, B.B.

1992-12-01

95

The hydrogen/deuterium isotope effect of the host material on the lifetime of organic light-emitting diodes.  

PubMed

The hydrogen/deuterium primary kinetic isotope effect provides useful information about the degradation mechanism of OLED host materials. Thus, replacement of labile C-H bonds in the host with C-D bonds increases the device lifetime by a factor of five without loss of efficiency, and replacement with C-C bonds by a factor of 22.5. PMID:25325237

Tsuji, Hayato; Mitsui, Chikahiko; Nakamura, Eiichi

2014-12-01

96

Hydrogen and deuterium profiling at the surface of zirconium alloys. I. The effects of surface preparation  

NASA Astrophysics Data System (ADS)

The H( 15N, ??) 12 C and D( 3He, p)? reactions have been used to measure hydrogen and deuterium profiles in Zr-2.5 wt% Nb alloys loaded to contain 40-150 ppm by weight H or 56-108 ppm D. Excellent agreement is found between the results obtained by these two different techniques. Large surface H(D) peaks are found after fine metallographic sample preparation techniques. The peaks may be substantially reduced by using a fine machining operation (as the last step in surface preparation) or may be totally removed by vacuum annealing. The surface peaks appear to be associated with hydride/deuteride particles embedded in the surface layers during metallographic polishing.

Stern, A.; Khatamian, D.; Laursen, T.; Weatherly, G. C.; Perz, J. M.

1987-01-01

97

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

PubMed Central

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

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

2012-01-01

98

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

DOEpatents

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.

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

1988-01-01

99

The HERMES polarized hydrogen and deuterium gas target in the HERA electron storage ring  

NASA Astrophysics Data System (ADS)

The HERMES hydrogen and deuterium nuclear-polarized gas targets have been in use since 1996 with the polarized electron beam of HERA at DESY to study the spin structure of the nucleon. Polarized atoms from a Stern-Gerlach Atomic Beam Source are injected into a storage cell internal to the HERA electron ring. Atoms diffusing from the center of the storage cell into a side tube are analyzed to determine the atomic fraction and the atomic polarizations. The atoms have a nuclear polarization, the axis of which is defined by an external magnetic holding field. The holding field was longitudinal during 1996-2000, and was changed to transverse in 2001. The design of the target is described, the method for analyzing the target polarization is outlined, and the performance of the target in the various running periods is presented.

Airapetian, A.; Akopov, N.; Akopov, Z.; Amarian, M.; Andrus, A.; Aschenauer, E. C.; Augustyniak, W.; Avakian, R.; Avetissian, A.; Avetissian, E.; Bailey, P.; Balin, D.; Baumgarten, C.; Beckmann, M.; Belostotski, S.; Bianchi, N.; Blok, H. P.; Böttcher, H.; Borissov, A.; Borysenko, A.; Bouwhuis, M.; Braun, B.; Brüll, A.; Bryzgalov, V.; Capitani, G. P.; Capiluppi, M.; Chen, T.; Ciullo, G.; Contalbrigo, M.; Court, G.; Dalpiaz, P. F.; De Leo, R.; Demey, M.; De Nardo, L.; De Sanctis, E.; Devitsin, E.; Di Nezza, P.; Düren, M.; Ehrenfried, M.; Elalaoui-Moulay, A.; Elbakian, G.; Ellinghaus, F.; Elschenbroich, U.; Fabbri, R.; Fantoni, A.; Fechtchenko, A.; Felawka, L.; Frullani, S.; Gapienko, G.; Gapienko, V.; Garibaldi, F.; Garrow, K.; Gavrilov, G.; Gharibyan, V.; Graw, G.; Grebeniouk, O.; Gregor, I. M.; Hadjidakis, C.; Haeberli, W.; Hafidi, K.; Hartig, M.; Hasch, D.; Heesbeen, D.; Henoch, M.; Hertenberger, R.; Hesselink, W. H. A.; Hillenbrand, A.; Hoek, M.; Holler, Y.; Hommez, B.; Hristova, I.; Iarygin, G.; Ivanilov, A.; Izotov, A.; Jackson, H. E.; Jgoun, A.; Kaiser, R.; Kinney, E.; Kisselev, A.; Kobayashi, T.; Koch, N.; Kolster, H.; Kopytin, M.; Korotkov, V.; Kozlov, V.; Krauss, B.; Krivokhijine, V. G.; Lagamba, L.; Lapikás, L.; Laziev, A.; Lenisa, P.; Liebing, P.; Linden-Levy, L. A.; Lorenzon, W.; Lu, H.; Lu, J.; Lu, S.; Ma, B.-Q.; Maiheu, B.; Makins, N. C. R.; Mao, Y.; Marianski, B.; Marukyan, H.; Mexner, V.; Meyners, N.; Mussa, R.; Mikloukho, O.; Miller, C. A.; Miyachi, Y.; Muccifora, V.; Nagaitsev, A.; Nappi, E.; Naryshkin, Y.; Nass, A.; Negodaev, M.; Nowak, W.-D.; Oganessyan, K.; Ohsuga, H.; Osborne, A.; Pickert, N.; Potterveld, D. H.; Raithel, M.; Reggiani, D.; Reimer, P. E.; Reischl, A.; Reolon, A. R.; Riedl, C.; Rith, K.; Rosner, G.; Rostomyan, A.; Rubacek, L.; Rubin, J.; Ryckbosch, D.; Salomatin, Y.; Sanjiev, I.; Savin, I.; Schill, C.; Schnell, G.; Schüler, K. P.; Seele, J.; Seidl, R.; Seitz, B.; Shanidze, R.; Shearer, C.; Shibata, T.-A.; Shutov, V.; Sinram, K.; Sommer, W.; Stancari, M.; Statera, M.; Steffens, E.; Steijger, J. J. M.; Stenzel, H.; Stewart, J.; Stinzing, F.; Tait, P.; Tanaka, H.; Taroian, S.; Tchuiko, B.; Terkulov, A.; Trzcinski, A.; Tytgat, M.; Vandenbroucke, A.; van der Nat, P.; van der Steenhoven, G.; van Haarlem, Y.; Vetterli, M. C.; Vikhrov, V.; Vincter, M. G.; Vogel, C.; Volmer, J.; Wang, S.; Wendland, J.; Wilbert, J.; Wise, T.; Ybeles Smit, G.; Ye, Y.; Ye, Z.; Yen, S.; Zihlmann, B.; Zupranski, P.

2005-03-01

100

Observation of crystallization slowdown in supercooled para-hydrogen and ortho-deuterium quantum liquid mixtures  

E-print Network

We report a quantitative experimental study of the crystallization kinetics of supercooled quantum liquid mixtures of para-hydrogen (pH$_2$) and ortho-deuterium (oD$_2$) by high spatial resolution Raman spectroscopy of liquid microjets. We show that in a wide range of compositions the crystallization rate of the isotopic mixtures is significantly reduced with respect to that of the pure substances. To clarify this behavior we have performed path-integral simulations of the non-equilibrium pH$_2$-oD$_2$ liquid mixtures, revealing that differences in quantum delocalization between the two isotopic species translate into different effective particle sizes. Our results provide first experimental evidence for crystallization slowdown of quantum origin, offering a benchmark for theoretical studies of quantum behavior in supercooled liquids.

Matthias Kühnel; José M. Fernández; Filippo Tramonto; Guzmán Tejeda; Elena Moreno; Anton Kalinin; Marco Nava; Davide E. Galli; Salvador Montero; Robert E. Grisenti

2014-10-10

101

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

NASA Astrophysics Data System (ADS)

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.

Rajabi, Khadijeh

2015-01-01

102

Determination of hydrogen/deuterium ratio with neutron measurements on MAST  

SciTech Connect

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.

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

103

Activation of AMP-activated protein kinase revealed by hydrogen/deuterium exchange Mass Spectrometry  

PubMed Central

Summary 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 by 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 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

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

2013-01-01

104

Intertwined structured and unstructured regions of exRAGE identified by monitoring hydrogen-deuterium exchange.  

PubMed

Receptor for advanced glycation end products (RAGE) is a multiligand receptor that is engaged in many pathological processes. Potentially beneficial modification of its activity requires sound knowledge of its structural properties. However, up to now, only the structures of its separated domains have been published or deposited in databases. In this work, we used hydrogen-deuterium exchange and mass spectrometry to gain insight into the structural properties of exRAGE (extracellular region of RAGE)--the full extracellular part of the protein. The present work indicates the common and disparate features of full exRAGE as compared to the structural models of its separate domains. The highlight of the present study is the contrasting behavior of the different regions of the protein, with the protected regions neighboring fully exposed parts especially in the N-terminal V domain. PMID:20732329

Kupniewska-Kozak, Anna; Gospodarska, Emilia; Dadlez, Michal

2010-10-15

105

Oligomerization interface of RAGE receptor revealed by MS-monitored hydrogen deuterium exchange.  

PubMed

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

Sitkiewicz, Ewa; Tarnowski, Krzysztof; Pozna?ski, Jaros?aw; Kulma, Magdalena; Dadlez, Michal

2013-01-01

106

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

PubMed Central

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

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

2013-01-01

107

Experimental resolution of deuterium and hydrogen depth profiling with the nuclear reactions D(3He,p)? and p(15N,?,?)12C  

NASA Astrophysics Data System (ADS)

In this paper well defined test samples are used to show how the analysis depth and the matrix material influence the depth resolution of nuclear reaction analysis. The reaction D(3He,p)? is used to detect deuterium. By covering 10 nm thin deuterated amorphous carbon (a-C:D) films on silicon with tungsten (ZW = 74) and titanium (ZTi = 22) of various thicknesses between 500 nm and 8 ?m the influence of the atomic number and the overlayer thickness on the depth resolution is studied. The most probable depth profiles are calculated from the experimental data with the program NRADC, which implements Bayesian statistics. The resulting apparent layer width of the deuterium containing layer broadens with increasing thickness of the coating and this broadening is more pronounced for coatings with higher Z. These apparent layer widths are a measure for the experimentally achievable depth resolution. Their absolute values are in the same range as the theoretical optimum calculated with RESOLNRA. To investigate the depth resolution of the p(N,?,?)C reaction, a 12 nm thin hydrogenated amorphous carbon (a-C:H) film on silicon and a pure tungsten sample are analysed. The width of the instrument function of this method is deduced from the surface hydrogen peak of the pure tungsten sample. The two methods are compared.

Bielesch, S.; Oberkofler, M.; Becker, H.-W.; Maier, H.; Rogalla, D.; Schwarz-Selinger, T.; Linsmeier, Ch.

2013-12-01

108

Nucleon Polarizability Contribution to the Hydrogen Lamb Shift and Hydrogen -- Deuterium Isotope Shift  

E-print Network

The correction to the hydrogen Lamb shift due to the proton electric and magnetic polarizabilities is expressed analytically through their static values, which are known from experiment. The numerical value of the correction to the hydrogen 1S state is $ - 71 \\pm 11 \\pm 7$ Hz. Correction to the H-D 1S-2S -- isotope shift due to the proton and neutron polarizabilities is estimated as $ 53 \\pm 9 \\pm 11$ Hz.

I. B. Khriplovich; R. A. Sen'kov

1998-09-30

109

Hydrogen adsorption and storage in carbon nanotubes  

Microsoft Academic Search

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

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

110

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

NASA Astrophysics Data System (ADS)

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.

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

2012-04-01

111

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

SciTech Connect

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.

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

2012-04-15

112

Conformational stability of ribonuclease T1 determined by hydrogen-deuterium exchange.  

PubMed Central

The hydrogen-deuterium exchange kinetics of 37 backbone amide residues in RNase T1 have been monitored at 25, 40, 45, and 50 degrees C at pD 5.6 and at 40 and 45 degrees C at pD 6.6. The hydrogen exchange rate constants of the hydrogen-bonded residues varied over eight orders of magnitude at 25 degrees C with 13 residues showing exchange rates consistent with exchange occurring as a result of global unfolding. These residues are located in strands 2-4 of the central beta-pleated sheet. The residues located in the alpha-helix and the remaining strands of the beta-sheet exhibited exchange behaviors consistent with exchange occurring due to local structural fluctuations. For several residues at 25 degrees C, the global free energy change calculated from the hydrogen exchange data was over 2 kcal/mol greater than the free energy of unfolding determined from urea denaturation experiments. The number of residues showing this unexpected behavior was found to increase with temperature. This apparent inconsistency can be explained quantitatively if the cis-trans isomerization of the two cis prolines, Pro-39 and Pro-55, is taken into account. The cis-trans isomerization equilibrium calculated from kinetic data indicates the free energy of the unfolded state will be 2.6 kcal/mol higher at 25 degrees C when the two prolines are cis rather than trans (Mayr LM, Odefey CO, Schutkowski M, Schmid FX. 1996. Kinetic analysis of the unfolding and refolding of ribonuclease T1 by a stopped-flow double-mixing technique. Biochemistry 35: 5550-5561). The hydrogen exchange results are consistent with the most slowly exchanging hydrogens exchanging from a globally higher free energy unfolded state in which Pro-55 and Pro-39 are still predominantly in the cis conformation. When the conformational stabilities determined by hydrogen exchange are corrected for the proline isomerization equilibrium, the results are in excellent agreement with those from an analysis of urea denaturation curves. PMID:9232639

Mullins, L. S.; Pace, C. N.; Raushel, F. M.

1997-01-01

113

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

E-print Network

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)*10^15 cm^(-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.

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

1999-11-05

114

Transitions between elongated conformations of ubiquitin [M+11H]11+ enhance hydrogen/deuterium exchange.  

PubMed

Hydrogen/deuterium (H/D) exchange reactions between different elongated conformations of [M + 11H](11+) ions of ubiquitin and D(2)O are studied by a combination of ion mobility spectrometry (IMS) and mass spectrometry techniques. Three conformers (B, C, and D), resolved in the IMS separation, each exchange ?27 hydrogens upon exposure to 0.06 Torr of D(2)O vapor for ?35 to 40 ms. However, a region of the IMS spectrum that appears between the C and D states (corresponding to ions that undergo a structural transition during the mobility separation) undergoes substantially more exchanges (?39 total sites, 44% more than the B, C, and D states). Selection and activation of the individual B, C, and D states reveals that the increased H/D exchange occurs during the transition between structures. Overall, these studies suggest a key process in establishing the maximum exchange levels involves structural transitions, which allow protected sites to be exposed for some fraction of the reaction time. Analysis of changes in exchange levels upon structural transitions can provide insight about common regions of structure that exist in the B, C, and D conformations. PMID:21449553

Bohrer, Brian C; Atlasevich, Natalya; Clemmer, David E

2011-04-21

115

Transitions between Elongated Conformations of Ubiquitin [M+11H]11+ Enhance Hydrogen/Deuterium Exchange  

PubMed Central

Hydrogen/deuterium (H/D) exchange reactions between different elongated conformations of [M+11H]11+ ions of ubiquitin and D2O are studied by a combination of ion mobility spectrometry (IMS) and mass spectrometry techniques. Three conformers (B, C, and D), resolved in the IMS separation, each exchange ~27 hydrogens upon exposure to 0.06 torr of D2O vapor for ~35 to 40 ms. However, a region of the IMS spectrum that appears between the C and D states (corresponding to ions that undergo a structural transition during the mobility separation) undergoes substantially more exchanges (~39 total sites, 44% more than the B, C, and D states). Selection and activation of the individual B, C, and D states reveals that the increased H/D exchange occurs during the transition between structures. Overall, these studies suggest a key process in establishing the maximum exchange levels involves structural transitions, which allow protected sites to be exposed for some fraction of the reaction time. Analysis of changes in exchange levels upon structural transitions can provide insight about common regions of structure that exist in the B, C, and D conformations. PMID:21449553

Bohrer, Brian C.; Atlasevich, Natalya; Clemmer, David E.

2011-01-01

116

Nanostructural activated carbons for hydrogen storage  

NASA Astrophysics Data System (ADS)

A series of nanostructured activated carbons have been synthesized from poly(ether ether ketone) (PEEK), and its derivatives. These carbons, with surface area exceeding 3000 m2/g and with average pore diameters of ? 20 A, are proven to be superior hydrogen storage materials, with hydrogen storage capacities up to 5.5 wt% at 77 K and 45 atm. The porous texture of these carbons was controlled via optimizing three synthetic steps: thermo-oxidation of PEEK in air, pyrolysis or carbonization of the oxidized PEEK in an inert atmosphere, and activation of the pre-carbonized PEEK with metal hydroxide. Thermo-oxidation of PEEK and carbonization process were thoroughly studied. These processes have been investigated by MDSC, FTIR, TGA and Py-MS. The pyrolysis or carbonization of PEEK involves the degradation of PEEK chains in three stages. Carbon morphology, including crystallinity and porous texture, is readily controlled by adjusting carbonization temperature. Activation of PEEK carbons, using inorganic bases and other activation agents, produces microporous carbons having a very narrow pore size distribution and an average pore diameter of ? 20 A. The activation control parameters including activation agent, activation temperature, time and carbon morphology have been investigated extensively. High surface area activated carbon is obtained by activating a highly amorphous carbon with a high activation agent/carbon ratio at 800°C. Theoretical calculations show that the pores with smaller diameter, especially smaller than 7 A, favor hydrogen adsorption. The experimental results confirm this fact and show that: (1) the hydrogen adsorption capacity per unit surface area at 77 K and 1 bar is larger in the smaller pores, (2) gravimetric hydrogen storage capacity (W(H2)) is directly proportional to the ultramicropore (< 7 A) volume; and (3) the volumetric hydrogen storage capacity is directly proportional to the volume fraction of ultramicropores in carbon. Hydrogen adsorption in activated carbons synthesized from PEEK and poly(ether imide) blends, poly(phenylene oxide), polybenzimidazole and lignin show similar trends. In addition, W( H2) progressively increases as surface area increases for the carbons with similar average pore diameters. Keywords. carbon, activated carbon, poly(ether ether ketone), poly(ether imide), poly(phenylene oxide), polybenzimidazole, lignin, gas adsorption, hydrogen storage

Li, Suoding

117

Global budget fo molecular hydrogen and its deuterium content: constraints from surface, aircraft, and oceanic cruise observations  

NASA Astrophysics Data System (ADS)

To improve our understanding of the global budget of molecular hydrogen, we present a new simulation of molecular hydrogen and its deuterium component (?D) using the GEOS-CHEM three dimensional global model of tropospheric chemistry. The primary sources of H2 (fossil fuel, biofuel, and biomass burning) used in the model are based on the GEOS-CHEM CO emissions inventory, scaled with the appropriate emission factors. Secondary sources from photochemical production arise from the photolysis of formaldehyde (resulting from oxidation of methane and biogenic volatile organic compounds, BVOCs) and account for an estimated 45% of the H2 source. There is considerable uncertainty in the source of H2 from formaldehyde, because of poor understanding of BVOC sources and chemistry. We also include a seasonally varying ocean source, based on a simulation of ocean nitrogen fixation. The main tropospheric sink, accounting for ~80% of the total, is uptake by enzymes in soils, a process which is poorly understood. The remainder loss is through oxidation by the hydroxyl radical (OH). The observed deuterium component of tropospheric H2 (expressed as ?D) is enriched by ~130‰ relative to Vienna Standard Mean Ocean Water [Gerst and Quay, 2000]. The combustion and ocean sources of H2 are isotopically depleted, while the photochemical sources are thought to be isotopically enriched [Gerst and Quay, 2001]. The soil sink for H2 shows little fractionation, while the OH sink shows considerable fractionation. Furthermore, stratosphere-troposphere exchange is believed to isotopically enrich H2 [Röckmann et al. 2003; Rahn et al. 2002]. We use H2 observations from the CMDL network (seasonal cycle, latitudinal and longitudinal gradients, aircraft observations) to constrain the budget of H2 in the atmosphere, in particular, the sink by soil uptake, the photochemical source, and ocean emissions. At the same time, we use observations of ?D from ocean cruises, aircraft, and ground sites to further constrain the budget of H2 and provide new isotopic constraints on the enrichment due to the photochemical source and stratosphere-troposphere exchange. Gerst S. and P. Quay, The deuterium content of atmospheric molecular hydrogen: Methods and initial measurements, J. Geosphy. Res., 105, 26,433-26,445, 2000. Gerst S. and P. Quay, Deuterium component of the global molecular hydrogen cycle, J. Geophys. Res., 106, 5021-5031, 2001. Rahn, T. et al., Extreme deuterium enrichment in the stratospheric hydrogen and the global atmospheric budget of H2, Nature, 424, 2003. Röckmann T., T. Rhee, and A. Engel, Heavy hydrogen in the stratosphere, Atmos. Chem. Phys., 3, 2015-2023, 2003.

Price, H. U.; Jaegle, L.; Quay, P.; Rice, A.; Novelli, P.

2006-05-01

118

Designing Microporus Carbons for Hydrogen Storage Systems  

SciTech Connect

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.

Alan C. Cooper

2012-05-02

119

Hydrogen storage in carbon nanotubes  

Microsoft Academic Search

Hydrogen is the cleanest, sustainable and renewable energy carrier, and a hydrogen energy system is expected to progressively replace the existing fossil fuels in the future, the latter are being depleted very fast and causes severe environmental problems. In particular, one potential use of hydrogen lies in powering zero-emission vehicles via a proton exchange membrane fuel cell to reduce atmosphere

Hui-Ming Cheng; Quan-Hong Yang; Chang Liu

2001-01-01

120

Hydrogen storage in sonicated carbon materials  

Microsoft Academic Search

.   The hydrogen storage in purified single-wall carbon nanotubes (SWNTs), graphite and diamond powder was investigated at room\\u000a temperature and ambient pressure. The samples were sonicated in 5 M HNO3 for various periods of time using an ultrasonic probe of the alloy Ti-6Al-4V. The goal of this treatment was to open the\\u000a carbon nanotubes. The maximum value of overall hydrogen storage

M. Hirscher; M. Becher; M. Haluska; U. Dettlaff-Weglikowska; A. Quintel; G. S. Duesberg; Y.-M. Choi; P. Downes; M. Hulman; S. Roth; I. Stepanek; P. Bernier

2001-01-01

121

Microscopic self-dynamics in liquid hydrogen and in its mixtures with deuterium  

SciTech Connect

We have measured the dynamic structure factor of liquid parahydrogen, pure and mixed with deuterium, in various thermodynamic conditions using incoherent inelastic neutron scattering. The experiments were carried out on TOSCA-II, a new time-of-flight, inverse-geometry, crystal-analyzer spectrometer. After an accurate data reduction, the high-energy parts of the neutron spectra recorded in backward scattering were studied through the modified Young and Koppel model, from which the mean kinetic energy values for a hydrogen molecule were estimated. In addition the low-energy parts of the neutron spectra recorded in forward scattering were analyzed in the framework of the Gaussian approximation and fitted through a Levesque-Verlet model for the velocity autocorrelation function. Thus various physical quantities are determined and compared with accurate path integral Monte Carlo simulations. Despite the excellent quality of these fits, the velocity autocorrelation functions derived from the forward-scattering data appear totally unable to properly describe the backward-scattering ones. These findings prove an unquestionable breakdown of the Gaussian approximation in semiquantum liquids. The present results appear of great interest and suggest further investigation on the limits of the widely used Gaussian approximation.

Colognesi, D.; Celli, M.; Zoppi, M. [Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi, Via Madonna del Piano, 50019 Sesto Fiorentino, FI (Italy); Neumann, M. [Institut fuer Experimentalphysik, Universitaet Wien, Strudlhofgasse 4, 1090 Vienna (Austria)

2004-12-01

122

Conformational Analysis of Recombinant Monoclonal Antibodies with Hydrogen/Deuterium Exchange Mass Spectrometry  

PubMed Central

Understanding the conformation of antibodies, especially those of therapeutic value, is of great interest. Many of the current analytical methods used to probe protein conformation face issues in the analysis of antibodies, either due to the nature of the antibody itself or the limitations of the method. One method that has recently been utilized for conformational analysis of antibodies is hydrogen/deuterium exchange mass spectrometry (H/DX MS). H/DX MS can be used to probe the conformation and dynamics of proteins in solution, requires small sample quantities, is compatible with many buffer systems, and provides peptide-level resolution. The application of H/DX MS to immunoglobulin gamma 1 (IgG1) recombinant monoclonal antibodies can provide information about IgG1 conformation, dynamics, and changes to conformation as a result of protein modification(s), changes in storage conditions, purification procedures, formulation, and many other parameters. In this article we provide a comprehensive HD/X MS protocol for the analysis of an antibody. PMID:23475726

Houde, Damian; Engen, John R.

2013-01-01

123

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

PubMed Central

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

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

2011-01-01

124

Ion Mobility Spectrometry-Hydrogen Deuterium Exchange Mass Spectrometry of Anions: Part 1. Peptides to Proteins  

NASA Astrophysics Data System (ADS)

Ion mobility spectrometry (IMS) coupled with hydrogen deuterium exchange (HDX)-mass spectrometry (MS) has been used to study the conformations of negatively-charged peptide and protein ions. Results are presented for ion conformers of angiotensin 1, a synthetic peptide (SP), bovine insulin, ubiquitin, and equine cytochrome c. In general, the SP ion conformers demonstrate a greater level of HDX efficiency as a greater proportion of the sites undergo HDX. Additionally, these ions exhibit the fastest rates of exchange. Comparatively, the angiotensin 1 ions exhibit a lower rate of exchange and HDX level presumably because of decreased accessibility of exchange sites by charge sites. The latter are likely confined to the peptide termini. Insulin ions show dramatically reduced HDX levels and exchange rates, which can be attributed to decreased conformational flexibility resulting from the disulfide bonds. For the larger ubiquitin and protein ions, increased HDX is observed for larger ions of higher charge state. For ubiquitin, a conformational transition from compact to more elongated species (from lower to higher charge states) is reflected by an increase in HDX levels. These results can be explained by a combination of interior site protection by compact conformers as well as decreased access by charge sites. The elongated cytochrome c ions provide the largest HDX levels where higher values correlate with charge state. These results are consistent with increased exchange site accessibility by additional charge sites. The data from these enhanced IMS-HDX experiments are described in terms of charge site location, conformer rigidity, and interior site protection.

Donohoe, Gregory C.; Khakinejad, Mahdiar; Valentine, Stephen J.

2015-04-01

125

The Deuterium to Hydrogen Abundance Ratio Towards a Fourth QSO: HS0105+1619  

E-print Network

We report the measurement of the primordial D/H abundance ratio towards QSO \\object. The column density of the hydrogen in the $z \\simeq 2.536$ Lyman limit system is high, \\lnhi $= 19.422 \\pm 0.009$ \\cmm, allowing for the deuterium to be seen in 5 Lyman series transitions. The measured value of the D/H ratio towards QSO \\object is found to be D/H$ = 2.54 \\pm 0.23 \\times 10^{-5}$. The metallicity of the system showing D/H is found to be $\\simeq 0.01$ solar, indicating that the measured D/H is the primordial D/H within the measurement errors. The gas which shows D/H is neutral, unlike previous D/H systems which were more highly ionized. Thus, the determination of the D/H ratio becomes more secure since we are measuring it in different astrophysical environments, but the error is larger because we now see more dispersion between measurements. Combined with prior measurements of D/H, the best D/H ratio is now D/H$ = 3.0 \\pm 0.4 \\times 10^{-5}$, which is 10% lower than the previous value. The new values for the baryon to photon ratio, and baryonic matter density derived from D/H are $\\eta = 5.6 \\pm 0.5 \\times 10^{-10} $ and \\ob $=0.0205 \\pm 0.0018$ respectively.

John M. O'Meara; David Tytler; David Kirkman; Nao Suzuki; Jason X. Prochaska; Dan Lubin; Arthur M. Wolfe

2001-01-18

126

Probing protein ligand interactions by automated hydrogen/deuterium exchange mass spectrometry.  

PubMed

Amide hydrogen/deuterium exchange is a powerful biophysical technique for probing changes in protein dynamics induced by ligand interaction. The inherent low throughput of the technology has limited its impact on drug screening and lead optimization. Automation increases the throughput of H/D exchange to make it compatible with drug discovery efforts. Here we describe the first fully automated H/D exchange system that provides highly reproducible H/D exchange kinetics from 130 ms to 24 h. Throughput is maximized by parallel sample processing, and the system can run H/D exchange assays in triplicate without user intervention. We demonstrate the utility of this system to differentiate structural perturbations in the ligand-binding domain (LBD) of the nuclear receptor PPARgamma induced upon binding a full agonist and a partial agonist. PPARgamma is the target of glitazones, drugs used for treatment of insulin resistance associated with type II diabetes. Recently it has been shown that partial agonists of PPARgamma have insulin sensitization properties while lacking several adverse effects associated with full agonist drugs. To further examine the mechanism of partial agonist activation of PPARgamma, we extended our studies to the analysis of ligand interactions with the heterodimeric complex of PPARgamma/RXRalpha LBDs. To facilitate analysis of H/D exchange of large protein complexes, we performed the experiment with a 14.5-T Fourier transform ion cyclotron resonance mass spectrometer capable of measuring mass with accuracy in the ppb range. PMID:16478090

Chalmers, Michael J; Busby, Scott A; Pascal, Bruce D; He, Yuanjun; Hendrickson, Christopher L; Marshall, Alan G; Griffin, Patrick R

2006-02-15

127

Elastic properties of Pd-hydrogen, Pd-deuterium, and Pd-tritium single crystals  

SciTech Connect

We used a resonant-ultrasound-spectroscopy technique to measure the three independent elastic constants of PdH{sub x}, PdD{sub x}, and PdT{sub x} single crystals at 300 K. For 0.1x0.62 our PdH{sub x} crystals are two-phase mixtures of coherent {alpha} and {beta} hydride phases. For increasing x in this range, C{sub 44} decreases monotonically whereas C'=12(C11-C12) has a concave parabolic dependence. This difference is because C' is softened by an anelastic relaxation resulting from acoustic-stress-induced changes in the shape of the coherent lenticular-shape precipitates ({beta}-hydride precipitates in {alpha}-hydride matrix and {alpha}-hydride precipitates in {beta}-hydride matrix). In the {beta}-phase C' and C{sub 44} decrease with increasing hydrogen (or deuterium or tritium) content. Furthermore, C' exhibits a strong isotope effect whereas C{sub 44} does not. This effect is attributed to differences in the excitation of optical phonons in Pd-H, Pd-D and Pd-T.

Schwarz, R.B. [Los Alamos National Laboratory, MSTs, Division and ESA Mail Stop G755, Los Alamos, NM 87545 (United States)]. E-mail: rxzs@lanl.gov; Bach, H.T. [Los Alamos National Laboratory, MSTs, Division and ESA Mail Stop G755, Los Alamos, NM 87545 (United States); Harms, U. [Los Alamos National Laboratory, MSTs, Division and ESA Mail Stop G755, Los Alamos, NM 87545 (United States); Tuggle, D. [Los Alamos National Laboratory, MSTs, Division and ESA Mail Stop G755, Los Alamos, NM 87545 (United States)

2005-02-01

128

Real-time Hydrogen/Deuterium Exchange Kinetics via Supercharged Electrospray Ionization Tandem Mass Spectrometry  

PubMed Central

Amide hydrogen/deuterium exchange (HDX) rate constants of bovine ubiquitin in an ammonium acetate solution containing 1% of the electrospray ionization (ESI) “supercharging” reagent m-nitrobenzyl alcohol (m-NBA) were obtained using top-down, electron transfer dissociation (ETD) tandem mass spectrometry (MS). The supercharging reagent replaces the acid and temperature “quench” step in the conventional MS approach to HDX experiments by causing rapid protein denaturation to occur in the ESI droplet. The higher charge state ions that are produced with m-NBA are more unfolded, as measured by ion mobility, and result in higher fragmentation efficiency and higher sequence coverage with ETD. Single amino acid resolution was obtained for 44 of 72 exchangeable amide sites, and summed kinetic data were obtained for regions of the protein where adjacent fragment ions were not observed, resulting in an overall spatial resolution of 1.3 residues. Comparison of these results with previous values from NMR indicates that the supercharging reagent does not cause significant structural changes to the protein in the initial ESI solution, and that scrambling or back-exchange is minimal. This new method for top-down HDX-MS enables real-time kinetic data measurements under physiological conditions, similar to those obtained using NMR, with comparable spatial resolution and significantly better sensitivity. PMID:20942406

Sterling, Harry J.; Williams, Evan R.

2010-01-01

129

Using hydrogen-deuterium exchange to monitor protein structure in the presence of gold nanoparticles.  

PubMed

The potential applications of protein-functionalized gold nanoparticles (AuNPs) have motivated many studies characterizing protein-AuNP interactions. However, the lack of detailed structural information has hindered our ability to understand the mechanism of protein adsorption on AuNPs. In order to determine the structural perturbations that occur during adsorption, hydrogen/deuterium exchange (HDX) of amide protons was measured for two proteins by NMR. Specifically, we measured both slow (5-300 min) and fast (10-500 ms) H/D exchange rates for GB3 and ubiquitin, two well-characterized proteins. Overall, amide exchange rates are very similar in the presence and absence of AuNPs, supporting a model where the adsorbed protein remains largely folded on the AuNP surface. Small differences in exchange rates are observed for several loop residues, suggesting that the secondary structure remains relatively rigid while loops and surface residues can experience perturbations upon binding. Strikingly, several of these residues are close to lysines, which supports a model where positive surface residues may interact favorably with AuNP-bound citrate. Because these proteins appear to remain folded on AuNP surfaces, these studies suggest that it may be possible to engineer functional AuNP-based nanoconjugates without the use of chemical linkers. PMID:25265213

Wang, Ailin; Vo, Tam; Le, Vu; Fitzkee, Nicholas C

2014-12-11

130

ORIGINAL RESEARCH Hydrogen and carbon isotope fractionation during  

E-print Network

ORIGINAL RESEARCH Hydrogen and carbon isotope fractionation during degradation of chloromethane, hydrogen isotope fractionation, methylotrophic bacteria. Correspondence Thierry Nadalig, Universite de and abiotic processes. In this study, we measured hydrogen and carbon isotope fractionation of the remaining

Paris-Sud XI, Université de

131

CARBON NANOTUBE MATERIALS FOR HYDROGEN STORAGE  

Microsoft Academic Search

Carbon single-wall nanotubes (SWNTs) are essentially elongated pores of molecular dimensions and are capable of adsorbing hydrogen at relatively high temperatures and low pressures. This behavior is unique to these materials and indicates that SWNTs are the ideal building block for constructing safe, efficient, and high energy density adsorbents for hydrogen storage applications. In past work we developed methods for

A. C. Dillon; T. Gennett; J. L. Alleman; K. M. Jones; P. A. Parilla

132

Desorption of hydrogen trapped in carbon and graphite  

NASA Astrophysics Data System (ADS)

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.

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

2013-11-01

133

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

NASA Astrophysics Data System (ADS)

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.

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

2012-02-01

134

Enumeration of labile hydrogens in natural organic matter by use of hydrogen/deuterium exchange Fourier transform ion cyclotron resonance mass spectrometry.  

PubMed

A method to enumerate labile hydrogens in all constituents of molecular ensemble of natural organic matter (NOM) based on our previously developed simple hydrogen/deuterium (H/D) exchange (electrospray ionization (ESI) ion source (Kostyukevich et al. Anal. Chem. 2013, 85, 5330) and ultra-high-resolution Fourier transform ion cyclotron resonance mass spectrometry is presented. The method was applied for analysis of Suwannee River fulvic acid (SRFA), which is an International Humic Substances Society standard, as well as Siberian crude oil; and lignosulfonate. We found that SRFA and lignosulfonate molecules contain 2-5 labile hydrogens, and their number increases with the number of oxygens in the molecule. Also, we observed that compounds of Siberian crude oil ionizing in positive-ESI mode do not have labile hydrogens, while compounds ionizing in negative-ESI mode have one labile hydrogen that detaches during ESI ionization. PMID:24098913

Kostyukevich, Yury; Kononikhin, Alexey; Popov, Igor; Kharybin, Oleg; Perminova, Irina; Konstantinov, Andrey; Nikolaev, Eugene

2013-11-19

135

Hydrogen storage on activated carbon. Final report  

SciTech Connect

The project studied factors that influence the ability of carbon to store hydrogen and developed techniques to enhance that ability in naturally occurring and factory-produced commercial carbon materials. During testing of enhanced materials, levels of hydrogen storage were achieved that compare well with conventional forms of energy storage, including lead-acid batteries, gasoline, and diesel fuel. Using the best materials, an electric car with a modern fuel cell to convert the hydrogen directly to electricity would have a range of over 1,000 miles. This assumes that the total allowable weight of the fuel cell and carbon/hydrogen storage system is no greater than the present weight of batteries in an existing electric vehicle. By comparison, gasoline cars generally are limited to about a 450-mile range, and battery-electric cars to 40 to 60 miles. The project also developed a new class of carbon materials, based on polymers and other organic compounds, in which the best hydrogen-storing factors discovered earlier were {open_quotes}molecularly engineered{close_quotes} into the new materials. It is believed that these new molecularly engineered materials are likely to exceed the performance of the naturally occurring and manufactured carbons seen earlier with respect to hydrogen storage.

Schwarz, J.A. [Syracuse Univ., NY (United States). Dept. of Chemical Engineering and Materials Science

1994-11-01

136

Hydrogen--Deuterium 1S--2S Isotope Shift and the Structure of the Deuteron A. Huber, Th. Udem, B. Gross, J. Reichert, M. Kourogi \\Lambda , K. Pachucki \\Lambda\\Lambda , M. Weitz, and T. W. Hansch  

E-print Network

Hydrogen--Deuterium 1S--2S Isotope Shift and the Structure of the Deuteron A. Huber, Th. Udem, B determined the hydrogen--deuterium isotope shift of the 1S--2S two--photon resonance with a 150 fold increase--based electron scattering experiments [2--4]. In 1993 optical spectroscopic measurements of the hydrogen

Pachucki, Krzysztof

137

Theoretical modeling of infrared spectra of the hydrogen and deuterium bond in aspirin crystal  

NASA Astrophysics Data System (ADS)

An extended quantum theoretical approach of the ? IR lineshape of cyclic dimers of weakly H-bonded species is proposed. We have extended a previous approach [M.E.-A. Benmalti, P. Blaise, H.T. Flakus, O. Henri-Rousseau, Chem. Phys. 320 (2006) 267] by accounting for the anharmonicity of the slow mode which is described by a "Morse" potential in order to reproduce the polarized infrared spectra of the hydrogen and deuterium bond in acetylsalicylic acid (aspirin) crystals. From comparison of polarized IR spectra of isotopically neat and isotopically diluted aspirin crystals it resulted that centrosymmetric aspirin dimer was the bearer of the crystal main spectral properties. In this approach, the adiabatic approximation is performed for each separate H-bond bridge of the dimer and a strong non-adiabatic correction is introduced into the model via the resonant exchange between the fast mode excited states of the two moieties. Within the strong anharmonic coupling theory, according to which the X-H?⋯Y high-frequency mode is anharmonically coupled to the H-bond bridge, this model incorporated the Davydov coupling between the excited states of the two moieties, the quantum direct and indirect dampings and the anharmonicity for the H-bond bridge. The spectral density is obtained within the linear response theory by Fourier transform of the damped autocorrelation functions. The evaluated spectra are in fairly good agreement with the experimental ones by using a minimum number of independent parameters. The effect of deuteration has been well reproduced by reducing simply the angular frequency of the fast mode and the anharmonic coupling parameter.

Ghalla, Houcine; Rekik, Najeh; Michta, Anna; Oujia, Brahim; Flakus, Henryk T.

2010-01-01

138

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

NASA Technical Reports Server (NTRS)

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.

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

1973-01-01

139

Relaxation of Hydrogen and Deuterium Atoms in Storage Cells B. Braun, G. Graw, H. Kolster, A. Metz, K.Reinmuller, P. Schiemenz  

E-print Network

Relaxation of Hydrogen and Deuterium Atoms in Storage Cells B. Braun, G. Graw, H. Kolster, A. Metz and nuclear polar­ ization of hydrogen as function of the magnetic field for a drifilm coated storage cell with test storage cells of mean wall collision numbers up to 3500. The HERMES experiment at the HERA

140

On the control of carbon nanostructures for hydrogen storage applications  

E-print Network

On the control of carbon nanostructures for hydrogen storage applications Patrice Guay a , Barry L April 2004 Available online 25 May 2004 Abstract The storage of hydrogen in different carbon nanofibers, Doped carbon; C. Molecular simulation; D. Gas storage 1. Introduction Hydrogen storage in carbon

Rochefort, Alain

141

Solvent deuterium isotope effects in the catalysis of oxygen-18 exchange by human carbonic anhydrase II.  

PubMed

By measuring the rate of exchange at chemical equilibrium of 18O between HCO3- and H2O catalyzed by human carbonic anhydrase II in the absence of buffers, we have determined the rate of release from the enzyme of water bearing substrate oxygen. The ratio of this rate measured in H2O to the rate measured in D2O, the solvent deuterium isotope effect, is between 4 and 9 in the range of pH(D) from 5.8 to 8.0, with a value of 8.0 +/- 0.7 at pH(D) 6.6 (uncorrected pH meter reading). The magnitude of this isotope effect at pH(D) 6.6 has an exponential dependence on the atom fraction of deuterium in solvent water. We conclude that an intramolecular proton transfer between a proton shuttle group on the enzyme and the active site is rate limiting for the release from the enzyme of water bearing substrate oxygen and involves a change in bonding of more than one proton. In contrast, the solvent deuterium isotope effect on the intermolecular proton transfer between the external buffer imidazole and the active site (or proton shuttle group) of the enzyme is small, 2.3 at pH(D) 7.0, as determined from initial velocity experiments. With a rate constant near 9 X 10(8) M-1 s-1, this intermolecular transfer is limited to a significant extent by diffusion processes. PMID:6817788

Tu, C K; Silverman, D N

1982-12-01

142

Hot-carrier stress effects on gate-induced-drain leakage current in n-channel MOSFETs studied by hydrogen\\/deuterium isotope effect  

Microsoft Academic Search

The degradation of gate-induced-drain leakage (GIDL) current under hot-carrier stress (HCS) has been studied in n-channel MOSFETs that were annealed in hydrogen (H) or deuterium (D). It is found that the degradation of GIDL current (IGIDL) can be effectively suppressed by deuterium passivation of interface traps. By using the H\\/D isotope effect, the impacts of oxide charge trapping (?Nox) and

Kangguo Cheng; Joseph W. Lyding

2003-01-01

143

Rapid Annealing Of Amorphous Hydrogenated Carbon  

NASA Technical Reports Server (NTRS)

Report describes experiments to determine effects of rapid annealing on films of amorphous hydrogenated carbon. Study represents first efforts to provide information for applications of a-C:H films where rapid thermal processing required. Major finding, annealing causes abrupt increase in absorption and concomitant decrease in optical band gap. Most of change occurs during first 20 s, continues during longer annealing times. Extend of change increases with annealing temperature. Researchers hypothesize abrupt initial change caused by loss of hydrogen, while gradual subsequent change due to polymerization of remaining carbon into crystallites or sheets of graphite. Optical band gaps of unannealed specimens on silicon substrates lower than those of specimens on quartz substrates.

Alterovitz, Samuel A.; Pouch, John J.; Warner, Joseph D.

1989-01-01

144

A deuterium and carbon nuclear magnetic resonance spectroscopic investigation of blood flow and carbohydrate metabolism  

SciTech Connect

The purpose of this study is the development and application of nuclear magnetic resonance (NMR) spectroscopic techniques for this study of whole tissue metabolism, tissue perfusion and blood flow. The feasibility of spin imaging deuterium-enriched tissue water is demonstrated in cat brain in vivo and in situ. The potential application of D{sub 2}O administration to deuterium-flow-imaging is considered. NMR investigations of hepatic carbohydrate metabolism were performed in rat liver in vivo and in situ. A coaxial, double-surface-coil, double-resonance probe was developed for carbon detection while decoupling neighboring proton scalar interactions ({sup 13}C-({sup 1}H)) in hepatic tissue within the living animal. Hormonal and substrate regulation of hepatic glucose and glycogen metabolism was investigated by monitoring the metabolic fate of an administered c-dose of (1-{sup 13}C)glucose. Label flux was directed primarily into newly-synthesized {sup 13}C-labeled glycogen. A multiple resonance ({sup 1}H, {sup 13}C, {sup 31}P) liver perfusion probe was designed for complimentary carbohydrate metabolic studies in rat liver in vitro. A description of the {sup 13}C-({sup 1}H)/{sup 31}P NMR perfusion probe is given. The surgical technique used for liver excision and peripheral life-support apparatus required to maintain hepatic function are also detailed.

Bosch, C.S.E.

1988-01-01

145

Hydrogen storage by carbon materials  

Microsoft Academic Search

In order for fuel cells to become a practical means of supplying power for road vehicles it will be necessary for a viable method of on-board hydrogen storage to be identified and implemented. Target values that must be achieved for the critical parameters in such a system have been drawn up by the US Department of Energy. It is quite

R. Ströbel; J. Garche; P. T. Moseley; L. Jörissen; G. Wolf

2006-01-01

146

Isotopic multiplets in the carbon-13 NMR spectra of aniline derivatives and nucleosides with partially deuterated amino groups: effects of intra- and intermolecular hydrogen bonding  

SciTech Connect

In aniline derivatives, the carbon-13 resonances of atoms bearing partially deuterated amino groups, as well as the resonances of vicinal carbon atoms, appear as multiplets. This phenomenon, which is due to upfield deuterium isotope effects on carbon-13 chemical shifts, is observed under conditions of slow hydrogen exchange (e.g., in Me/sub 2/SO solutions). The effects are larger for groups engaged in intramolecular hydrogen bonds. Empirical expressions are presented that relate isotope effects with amino proton chemical shifts and hydrogen bond energies. Isotopic multiplets are also observed in the carbon-13 NMR spectra of partially deuterated nucleosides. The multiplet structure is altered upon formation of base pairs. These results are interpreted in terms of hydrogen exchange reactions involving uridine (or thymidine) hydrogen-bonded dimers or changes in hydrogen bond energies upon formation of guanosine-cytidine complexes. Estimates are given for the energies of individual hydrogen bonds in Watson-Crick base pairs.

Reuben, J.

1987-01-21

147

Equilibrium carbon and hydrogen isotope fractionation in iron  

NASA Astrophysics Data System (ADS)

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.

Schauble, E. A.

2009-12-01

148

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

SciTech Connect

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.

Lingyan Zhu

2004-02-28

149

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

PubMed Central

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

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

2014-01-01

150

Mitigation of carbon erosion in beryllium seeded deuterium plasma under bombardment by argon and helium ions in PISCES-B  

NASA Astrophysics Data System (ADS)

The influence of argon and helium impurities on chemical erosion of carbon by deuterium and on the mitigation of erosion by the beryllium seeding has been studied in the PISCES-B linear plasma device. Optical spectroscopy has been used to quantify the amounts of Be, Ar and He in the deuterium plasma and to monitor the reduction of the CD band as a measure of carbon chemical erosion of the fine-grain graphite target. The addition of Ar and He has not resulted in an increase of the carbon erosion rate. Moreover, the characteristic time for the Be layer formation was in agreement with the reference exposures. It can be concluded, that for the covered range of experimental parameters the addition of Ar and He to plasma does not affect the formation of the protective Be carbide layer and the associated mitigation of carbon erosion.

Kreter, A.; Nishijima, D.; Baldwin, M. J.; Doerner, R. P.; Pospieszczyk, A.

2011-10-01

151

Deuterium isotope effects on gas phase ion-molecule hydrogen-bonding interactions: Alcohol-alkoxide and alcohol-chloride adduct ions  

Microsoft Academic Search

Fourier Transform Ion Cyclotron Resonance (FT-ICR) and High Pressure Mass Spectrometric (HPMS) measurements of the deuterium isotope effect and kinetics of adduct ion formation have been used to probe the nature of the potential describing the motion of the hydrogen in gas phase ion-molecule hydrogen-bonding interactions. Hydrogen-bonding systems reported in this paper are alkoxide ion and chloride ion solvated by

F. E. Wilkinson; M. Peschke; J. E. Szulejko; T. B. McMahon

1998-01-01

152

Stoichiometry: Elemental Analysis of Carbon and Hydrogen  

NSDL National Science Digital Library

This site provides a useful tutorial for applying principles of stoichiometry to determine the per cent composition by weight of carbon and hydrogen in unknown compounds. This information is then used to determine the empirical formulas of the unknowns. The empirical formula and molecular weight of the unknown compounds are then employed to determine the molecular formula.

David N. Blauch

153

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

E-print Network

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

Wu, Jianzhong

154

Irradiated interplanetary dust particles as a possible solution for the deuterium/hydrogen paradox of Earth's oceans  

NASA Technical Reports Server (NTRS)

Determining the source of Earth's oceans is a longstanding problem in planetary science. Possible sources of water include water ice or water of hydration of silicate minerals in the original material from which the bulk Earth accreted and water brought in by late-arriving planetesimals during the heavy bombardment period (4.5-3.8 Gyr ago) [Chyba, 1989, 1991]. Comets are an attractive source of water because their origin in the outer solar system is consistent with the long timescale for heavy bombardment. However, the high deuterium/hydrogen (D/H) ratio of the three comets that have been studied, Halley, Hyakutake, and Hale-Bopp, indicates that Earth must have had a source with a low-D/H ratio as well. Here we suggest that solar wind-implanted hydrogen on interplanetary dust particles (IDPs) provided the necessary low-D/H component of Earth's water inventory.

Pavlov, A. A.; Pavlov, A. K.; Kasting, J. F.

1999-01-01

155

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

E-print Network

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.

Winterberg, Friedwardt

2012-01-01

156

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

E-print Network

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.

Friedwardt Winterberg

2012-07-31

157

Intramolecular hydrogen bonding of the enol forms of ?-ketoamides and ?-ketothioamides. Deuterium isotope effects on 13C chemical shifts  

NASA Astrophysics Data System (ADS)

Deuterium isotope effects of 13C chemical shifts are studied in a series of enol and keto forms of ?-ketoamides and the corresponding thioamides. In addition, the 2,6-cyclohexanediketo-1-amides and thioamides are studied. The effects of ring size (five- and six-membered rings) on the isotope effects and the tautomeric nature of the systems are also looked into. Rather unusual isotope effects are found for the amides, indicating a tautomeric system of the ?C?ONHRCOHNHR type. This is supported by the 17O chemical shift studies. The isotope effects of the simple amides are compared with those of the tetracyclines and piroxicams. The study of N-phenyl-3-phenyl-3-oxo-propiothioamide at low temperature reveals that this thioamide exists as a mixture of s-cis and s-trans species. The isotope effects and the influence of intramolecular hydrogen bonding in the two species can thus be studied. Thioamides of indan-1,3-diones show tautomeric behaviour, as revealed by very large deuterium isotope effects of both signs. Deuteriation shifts the equilibrium in the direction of the thioamide. Finally, the tendency of a series of ?-hydroxy esters, thioesters, anhydrides, amides, thioamides, aldehydes and ketones to become tautomeric is discussed in terms of hydrogen bonding, isotope effects, 2?C(OD), and the nature of the acceptor.

Hansen, Poul Erik; Duus, Fritz; Bolvig, Simon; Jagodzinski, Tadeusz S.

1996-04-01

158

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

DOEpatents

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.

Lueking, Angela (State College, PA); Narayanan, Deepa (Redmond, WA)

2011-03-08

159

Formation of deuterium-carbon inventories in gaps of plasma facing components  

NASA Astrophysics Data System (ADS)

Plasma facing components for ITER will be manufactured as macro brush structures or with castellated surfaces. Material samples with gaps of similar geometry as intended for ITER were exposed to different plasma conditions in TEXTOR, DIII-D and ASDEX Upgrade. In all devices a decrease of both carbon and deuterium inventories at the side faces from the gap entrance into the gap with scale-lengths in the mm range is found. The fraction of D retained at the gap surfaces is in the range of 0.4-4% of the incident flux. Main parameters determining the retained D-fraction are the temperature of the respective surfaces and the carbon fraction in the incident flux. Extrapolation of tritium inventory growth rates to ITER dimensions assuming the measured retention fractions at T > 200 °C and using a D/T-flux distribution with a carbon fraction of ?1% from B2/EIRENE simulations of an ITER H-mode discharge yields a contribution to the increase of the total in-vessel tritium inventory in the range of 0.5-5 g T/discharge.

Krieger, K.; Jacob, W.; Rudakov, D. L.; Bastasz, R.; Federici, G.; Litnovsky, A.; Maier, H.; Rohde, V.; Strohmayer, G.; West, W. P.; Whaley, J.; Wong, C. P. C.; Asdex Upgrade; Diii-D Teams

2007-06-01

160

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

NASA Technical Reports Server (NTRS)

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.

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

1969-01-01

161

The Deuterium to Hydrogen Ratio in the Atmospheres of Jupiter and Titan.  

NASA Astrophysics Data System (ADS)

For determining the D/H ratios in the atmospheres of Titan and Jupiter, the 8.6 (mu)m band ((nu)(,6)) of CH(,3)D and the 7.7 (mu)m band ((nu)(,4)) of CH(,4) have been used. The (nu)(,6) band of CH(,3)D was observed in the laboratory at Stony Brook, and an absolute band intensity of 63.6 cm('-2)atm('-1) at 300 K and a constant hydrogen -broadened line width of 0.075 cm('-1)atm('-1) were obtained. Theoretical band models used for this thesis are also compiled. The accuracy of the random band models is improved by using real line strength distributions instead of the conventional simple models of line strength distributions. Several methods of saving computer time and improving accuracy in the line-by-line calculations are also discussed. The 8.6 (mu)m emission feature of Titan's infrared spectrum has been analyzed, using the Voyager temperature -pressure profile. Although both C(,3)H(,8) and CH(,3)D have bands at that wavelength, CH(,3)D turns out to be dominating the observed emission on Titan. A CH(,3)D/CH(,4) mixing ratio has been derived using these bands and the strong CH(,4) band at 7.7 (mu)m. The corresponding D/H ratio is. (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI). neglecting deuterium fractionation with other molecules. The main uncertainty in this value comes from the continuum emission characteristics. The D/H ratio is apparently significantly enhanced on Titan with respect to published values for Saturn. High resolution ((DELTA)(nu) = 1 cm('-1)) spectra of the 1100-1200 cm('-1) region of the central part of Jupiter have been analyzed. There is evidence for yearly variations in the tropospheric abundances of NH(,3), PH(,3), CH(,3)D and CH(,4). The best fit NH(,3) distribution curve shows a high mixing ratio NH(,3)/H(,2) = 3.3 (+OR-) 1.7 x 10('-4), below the 147 K layer (> 0.6 atmosphere). If NH(,3) ice particles are introduced as an opacity source, the NH(,3) mixing ratio below the 147 K layer can be lowered, but the fit is worse than the model excluding NH(,3) ice particles. The best fit PH(,3) distribution curve has a PH(,3)/H(,2) mixing ratio of 8.3 (+OR-) 2.0 x 10('-7) in the troposphere. A CH(,4)/H(,2) mixing ratio of 2.5 (+OR-) 0.4 x 10('-3) is found in the troposphere. The derived D/H ratio is. (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI). Most of the modeled flux in this spectral region comes from layer above the 170 K level (< 1 atmosphere).

Kim, Sang Joon

1982-03-01

162

Peptide-Column Interactions and Their Influence on Back Exchange Rates in Hydrogen/Deuterium Exchange-MS  

NASA Astrophysics Data System (ADS)

Hydrogen/deuterium exchange (HDX) methods generate useful information on protein structure and dynamics, ideally at the individual residue level. Most MS-based HDX methods involve a rapid proteolytic digestion followed by LC/MS analysis, with exchange kinetics monitored at the peptide level. Localizing specific sites of HDX is usually restricted to a resolution the size of the host peptide because gas-phase processes can scramble deuterium throughout the peptide. Subtractive methods may improve resolution, where deuterium levels of overlapping and nested peptides are used in a subtractive manner to localize exchange to smaller segments. In this study, we explore the underlying assumption of the subtractive method, namely, that the measured back exchange kinetics of a given residue is independent of its host peptide. Using a series of deuterated peptides, we show that secondary structure can be partially retained under quenched conditions, and that interactions between peptides and reversed-phase LC columns may both accelerate and decelerate residue HDX, depending upon peptide sequence and length. Secondary structure is induced through column interactions in peptides with a solution-phase propensity for structure, which has the effect of slowing HDX rates relative to predicted random coil values. Conversely, column interactions can orient random-coil peptide conformers to accelerate HDX, the degree to which correlates with peptide charge in solution, and which can be reversed by using stronger ion pairing reagents. The dependency of these effects on sequence and length suggest that subtractive methods for improving structural resolution in HDX-MS will not offer a straightforward solution for increasing exchange site resolution.

Sheff, Joey G.; Rey, Martial; Schriemer, David C.

2013-07-01

163

Gas-phase hydrogen/deuterium exchange in a travelling wave ion guide for the examination of protein conformations  

PubMed Central

Accumulating evidence suggests that solution-phase conformations of small globular proteins and large molecular protein assemblies can be preserved for milliseconds after electrospray ionization. Thus, the study of proteins in the gas-phase on this time-scale is highly desirable. Here we demonstrate that a travelling wave ion guide (TWIG) of a Synapt mass spectrometer offers a highly suitable environment for rapid and efficient gas-phase hydrogen/deuterium exchange (HDX). Gaseous ND3 was introduced into either the source TWIG or the TWIG located just after the ion mobility cell, such that ions underwent HDX as they passed through the ND3 on the way to the time-of-flight analyzer. The extent of deuterium labeling could be controlled by varying the quantity of ND3 or the speed of the travelling wave. The gas-phase HDX of model peptides corresponded to labeling of primarily fast exchanging sites due to the short labeling times (ranging from 0.1 to 10 ms). In addition to peptides, gas-phase HDX of ubiquitin, cytochrome c, lysozyme and apomyoglobin were examined. We conclude that HDX of protein ions in a TWIG is highly sensitive to protein conformation, enables the detection of conformers present on sub-milliseconds timescales and can readily be combined with ion mobility spectrometry. PMID:19921790

Rand, Kasper D.; Pringle, Steven D.; Murphy, James P.; Fadgen, Keith E.; Brown, Jeff; Engen, John R.

2009-01-01

164

Combining ion mobility spectrometry with hydrogen-deuterium exchange and top-down MS for peptide ion structure analysis.  

PubMed

The gas-phase conformations of electrosprayed ions of the model peptide KKDDDDIIKIIK have been examined by ion mobility spectrometry (IMS) and hydrogen deuterium exchange (HDX)-tandem mass spectrometry (MS/MS) techniques. [M+4H](4+) ions exhibit two conformers with collision cross sections of 418 Å(2) and 471 Å(2). [M+3H](3+) ions exhibit a predominant conformer with a collision cross section of 340 Å(2) as well as an unresolved conformer (shoulder) with a collision cross section of ~367 Å(2). Maximum HDX levels for the more compact [M+4H](4+) ions and the compact and partially-folded [M+3H](3+) ions are ~12.9, ~15.5, and ~14.9, respectively. Ion structures obtained from molecular dynamics simulations (MDS) suggest that this ordering of HDX level results from increased charge-site/exchange-site density for the more compact ions of lower charge. Additionally, a new model that includes two distance calculations (charge site to carbonyl group and carbonyl group to exchange site) for the computer-generated structures is shown to better correlate to the experimentally determined per-residue deuterium uptake. Future comparisons of IMS-HDX-MS data with structures obtained from MDS are discussed with respect to novel experiments that will reveal the HDX rates of individual residues. PMID:25267084

Khakinejad, Mahdiar; Kondalaji, Samaneh Ghassabi; Maleki, Hossein; Arndt, James R; Donohoe, Gregory C; Valentine, Stephen J

2014-12-01

165

Wave Packet Molecular Dynamics Simulations of the Equation of State of Hydrogen and Deuterium Under Extreme Conditions  

NASA Astrophysics Data System (ADS)

Recent laser shock-wave experiments by Da Silva et al.1 with deuterium in a regime where a plasma phase-trasition has been predicted5 are a topic of many current discussions (e.g.2,3,4,12,13). In this paper we apply "Wave Packet Molecular Dynamics" (WPMD) simulations to the equation of state of hydrogen at constant temperature T = 300 K and of deuterium at constant hugoniot E - E0 +(1)/(2)(V - V0)(p + p0) = 0 and compare them with experiments and several theoretical approaches. The WPMD method was originally used by Heller for a description of the scattering of composite particles like simple atoms and molecules7; later it was applied to Coulomb systems by Klakow et al.8,9. In the present version of our model the protons are treated as classical point-particles, whereas the electrons are represented by a completely anti-symmetrized Slater-sum of periodic Gaussian wavepackets.

Knaup, M.; Reinhard, P.-G.; Toepffer, C.

2001-09-01

166

Hysteresis during lithium insertion in hydrogen-containing carbons  

Microsoft Academic Search

The authors studied lithium insertion in hydrogen-containing carbons heated at temperatures near 700 C. High capacities with large hysteresis (lithium insertion into these carbons at nearly 0 V and removal at nearly 1 V) were shown to be proportional to the hydrogen content of the samples. It is believed that the lithium atoms may bind on hydrogen-terminated edges of hexagonal

Tao Zheng; J. R. Dahn; W. R. McKinnon

1996-01-01

167

Quantum rotation of hydrogen in single-wall carbon nanotubes  

E-print Network

Quantum rotation of hydrogen in single-wall carbon nanotubes C.M. Brown a,b , T. Yildirim b , D containing single-wall carbon nanotubes. These materials have attracted considerable interest recently due the ortho±para conversion of physisorbed hydrogen in a nanotube containing soot loaded with hydrogen. From

Yildirim, Taner

168

Hydrogen Raman shifts in carbon nanotubes from molecular dynamics simulation  

E-print Network

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

Brenner, Donald W.

169

Top-down mass spectrometry and hydrogen/deuterium exchange for comprehensive structural characterization of interferons: implications for biosimilars.  

PubMed

Rapid development in biopharmaceuticals has put high demands on analytical tools that can provide accurate and comprehensive characterization of protein drugs, including biosimilars. Although the enzyme digestion based "bottom-up" approach is usually the method of choice for this purpose, it only gives peptide-level information and sequence coverage is often incomplete. In this work, we used top-down MS with electron capture dissociation (ECD) to characterize both the primary and higher order structures of a therapeutic protein interferon and its variants. Accurate mass measurement at the intact protein level combined with top-down ECD fragmentation enabled unambiguous protein sequence confirmation and identification of all PTMs. Combining hydrogen/deuterium exchange and rapid disulfide reduction with top-down ECD on the LC time scale, we have investigated the differences in higher order structure between the protein variants, as well as the impact of PTMs on protein conformation. PMID:24574185

Pan, Jingxi; Borchers, Christoph H

2014-05-01

170

Low-temperature phases of dense hydrogen and deuterium by first-principles path-integral molecular dynamics  

NASA Astrophysics Data System (ADS)

The low-temperature phases of dense hydrogen and deuterium have been investigated using first-principles path-integral molecular dynamics, a technique that we have recently implemented in the ABINIT code and that allows to account for the quantum fluctuations of atomic nuclei. A massively parallelized scheme is applied to produce trajectories of several tens of thousands steps using a 64-atom supercell and a Trotter number of 64. The so-called phases I, II and III are studied and compared to the structures proposed in the literature. The quantum fluctuations produce configurational disorder and are shown to systematically enhance the symmetry of the system: a continuous gain of symmetry in the angular density of probability of the molecules is found from classical particles to quantum D2 and finally to quantum H2. Particular emphasis is made on the ``broken-symmetry'' phase (phase II).

Torrent, Marc; Geneste, Gregory

2012-02-01

171

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

PubMed

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

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

2000-01-01

172

Thermochemical generation of hydrogen and carbon dioxide  

NASA Technical Reports Server (NTRS)

Mixing of carbon in the form of high sulfur coal with sulfuric acid reduces the temperature of sulfuric acid decomposition from 830.degree. C. to between 300.degree. C. and 400.degree. C. The low temperature sulfuric acid decomposition is particularly useful in thermal chemical cycles for splitting water to produce hydrogen. Carbon dioxide is produced as a commercially desirable byproduct. Lowering of the temperature for the sulfuric acid decomposition or oxygen release step simplifies equipment requirements, lowers thermal energy input and reduces corrosion problems presented by sulfuric acid at conventional cracking temperatures. Use of high sulfur coal as the source of carbon for the sulfuric acid decomposition provides an environmentally safe and energy efficient utilization of this normally polluting fuel.

Lawson, Daniel D. (Inventor); England, Christopher (Inventor)

1984-01-01

173

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

Microsoft Academic Search

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

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

2007-01-01

174

Doped Carbon Nanotubes for Hydrogen Storage Ragaiy Zidan  

E-print Network

Doped Carbon Nanotubes for Hydrogen Storage Ragaiy Zidan Savannah River Technology Center Savannah-capacity hydrogen storage material. The final product should have favorable thermodynamics and kinetics- board hydrogen storage for transportation applications. One of the candidates for solid hydrogen storage

175

Photobiological hydrogen production and carbon dioxide sequestration  

NASA Astrophysics Data System (ADS)

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.

Berberoglu, Halil

176

Hydrogen-containing carbon nanostructures: synthesis and properties  

Microsoft Academic Search

Data on the interaction of carbon nanomaterials (fullerenes, carbon nanotubes, graphite nanofibres and their metal-doped modifications) with hydrogen are surveyed. New results on the preparation and properties of hydrofullerenes are presented. The prospects for the use of carbon nanomaterials as reversible hydrogen sorbents are discussed. The bibliography includes 183 references.

Boris P Tarasov; Natalya F Goldshleger; Aleksandr P Moravsky

2001-01-01

177

Use of CI-MS for the determination of deuterium content in hydrocarbons; The spectra boundary method for hydrogen-abstraction  

SciTech Connect

Chemical-ionization mass spectrometry (CI-MS) has both adavantages and disadvantages over electron-impact mass spectrometry (EI-MS) in the measurement of deuterium distributions in hydrocarbons. The advantage that CI maintains over EI is that, in many instances, only a small amount of fragmentation is generated in the ionization process, resulting in simpler interpretation of the spectra. The authors report on the spectra generated by a CI process that abstracts a hydrogen (or deuterium) atom. Although some information is lost in the abstraction process, almost complete recovery can be made mathematically so that useful information may be obtained from this technique.

Price, G.L.; Iglesia, E. (Exxon Research and Engineering Co., Annandale, NJ (USA). Corporate Research Labs.)

1989-07-01

178

Functionalized carbon nanostructures for hydrogen catalysis  

NASA Astrophysics Data System (ADS)

Sodium borohydride, NaBH4, is widely used as a source of pure hydrogen. Hydrogen is of interest because it is a source of clean energy. It can be converted directly into electrical energy by means of fuel cells. One of the objectives of this thesis was to develop a new catalytic process to (i) enhance the rate of hydrogen generation, and (ii) to achieve hydrogen generation equal to 100% of the theoretically expected value. The catalyst investigated in this research is constructed by starting from single wall carbon nanotubes (SWNT). This material has a very high specific surface area and good conductivity. The SWNT were formed into a paper by a special filtration process. Polysilazane, a polymeric precursor (Ceraset(TM)-SN from KiON Corp., Wiesbaden, Germany) was diluted by acetone and then layered onto SWNT paper. The Ceraset coated SWNT was then pyrolyzed at 1100°C for three hours to form a silicon carbonitride (SiCN), polymer derived ceramic (PDC), layer on the surface of SWNT filtered paper. This functionalized SiCN carbon nanotube paper (SiCN/CNT) was used as the substrate for catalyst dispersions. The catalyst consisted of transition metals, Pt/Pd/Ru. Suspension solutions of Pt, Pd and Ru were impregnated onto the SiCN/CNT paper with the expectation of creating a monolayer of these transition metals on surface of the SiCN/CNT substrate. It is likely that an interaction could occur between the transition metals and the silicon atoms present in the SiCN layer on the surface of the carbon nanotubes. It is known that transition metals and silicon react to form silicides, suggesting the formation of a strong Si-transition metal bond. Therefore, it is possible that this bond could provide good wetting of metal atoms on SiCN functionalized carbon nanotube substrate. In the limit a monolayer of the transition metals may be achieved, which would correspond to a near zero dihedral angle between the substrate and the cluster of transition metals. In such a scenario a very high activity of the catalyst can be achieved raising the figure of merit for hydrogen generation nearly to its highest possible value. The catalytic performance is also related to the intrinsic activity of chemical composition of the catalyst. In the present work, the use of catalysts of a ternary composition has been discovered to enhance the activity of the catalyst. The experiments presented in this work use Pt/Pd/Ru catalyzed SiCN/CNT as the catalyst to react with sodium borohydride for the hydrogen generation. The thickness of SiCN/CNT paper is one of the factors, which influences the hydrogen generation rate: thinner papers produce higher rates of hydrogen generation. The likely reason for this phenomenon is that hydrogen bubbles can become trapped within the mesh of carbon nanotubes that constitute the paper-like structure of the catalyst. It is hypothesized that hydrogen bubbles can escape more easily from the interior of the paper if the paper is thinner. The effect of the paper thickness on the hydrogen generation rate forms the first part of the thesis. In the next phase of the thesis, thin film structures of carbon nanotubes, about 300 nm high, were created to serve as the catalyst substrates. Transition metals were deposited on to these substrates by an electrophoretic process. In these catalysts huge increases in hydrogen generation rates, relative to the CNT-paper architecture, were achieved. Indeed the Figure of Merit (FOM), expressed as liters per minute of hydrogen generated per gram of the precious metals, per unit molar concentration of NaBH4, (Lmin-1g met-1[NaBH4]-1), of these "thin film CNT" catalysts was up to three orders of magnitude greater than could be achieved with the thick CNT paper, as described in the first part of the thesis. These values for the FOM are more than two orders of magnitude greater than the highest values for hydrogen generation from NaBH4 reported in the literature. The reaction mechanism and the catalytic efficiency in the present work is described in terms of an electric charge transfer, as has b

Hu, Lung-Hao

179

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

E-print Network

-terminal domain. Hydrogen bonds are of paramount importance in nucleic acid structure and function. Here we show that changes in the width and anharmonicity of vibrational potential energy wells of hydrogen bonded groups can be measured in nucleic acids and can...

Vakonakis, Ioannis

2005-08-29

180

Hexicon 2: Automated Processing of Hydrogen-Deuterium Exchange Mass Spectrometry Data with Improved Deuteration Distribution Estimation  

NASA Astrophysics Data System (ADS)

Hydrogen-deuterium exchange (HDX) experiments analyzed by mass spectrometry (MS) provide information about the dynamics and the solvent accessibility of protein backbone amide hydrogen atoms. Continuous improvement of MS instrumentation has contributed to the increasing popularity of this method; however, comprehensive automated data analysis is only beginning to mature. We present Hexicon 2, an automated pipeline for data analysis and visualization based on the previously published program Hexicon (Lou et al. 2010). Hexicon 2 employs the sensitive NITPICK peak detection algorithm of its predecessor in a divide-and-conquer strategy and adds new features, such as chromatogram alignment and improved peptide sequence assignment. The unique feature of deuteration distribution estimation was retained in Hexicon 2 and improved using an iterative deconvolution algorithm that is robust even to noisy data. In addition, Hexicon 2 provides a data browser that facilitates quality control and provides convenient access to common data visualization tasks. Analysis of a benchmark dataset demonstrates superior performance of Hexicon 2 compared with its predecessor in terms of deuteration centroid recovery and deuteration distribution estimation. Hexicon 2 greatly reduces data analysis time compared with manual analysis, whereas the increased number of peptides provides redundant coverage of the entire protein sequence. Hexicon 2 is a standalone application available free of charge under http://hx2.mpimf-heidelberg.mpg.de.

Lindner, Robert; Lou, Xinghua; Reinstein, Jochen; Shoeman, Robert L.; Hamprecht, Fred A.; Winkler, Andreas

2014-06-01

181

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

SciTech Connect

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.

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

182

Obtaining laser action near the Lyman-alpha line of hydrogen and deuterium  

Microsoft Academic Search

The aim of the present experiment was to study the feasibility of developing a powerful source of coherent radiation at wavelengths between 121.5 and 121.6 nanometers, using krypton and atomic hydrogen as the working media. (The resonance line of krypton is 2 nanometers away from the Lyman alpha line of hydrogen.) The intensity of the third harmonic (121.6 nanometers) is

S. A. Batishche; V. S. Burakov; V. G. Voronin; V. I. Gladushchak; V. A. Mostovnikov; P. A. Naumenkov; G. T. Razdobarin; A. N. Rubinov; V. V. Semenov; N. V. Tarasenko

1977-01-01

183

Nickel\\/Chromium oxide\\/Zirconium oxide Catalysts for Hydrogen\\/Deuterium Isotopic Exchange  

Microsoft Academic Search

Catalysts composed of nickel and promoted with different metal oxides proved to be suitable for H\\/D isotropic exchange between hydrogen and water vapour. They loss their activity due to water condensation on their surfaces. Several nickel\\/chromium oxide\\/zirconium oxide catalysts of different composition were prepared by the coprecipitation technique. The liquid phase activity of these catalysts were followed using the hydrogen

M. M. Abdel-Badei; A. El-Sharkawi; M. Abdel-Khalik; F. Abou El-Nour

1990-01-01

184

Effective Application of Bicelles for Conformational Analysis of G Protein-Coupled Receptors by Hydrogen/Deuterium Exchange Mass Spectrometry  

NASA Astrophysics Data System (ADS)

G protein-coupled receptors (GPCRs) have important roles in physiology and pathology, and 40% of drugs currently on the market target GPCRs for the treatment of various diseases. Because of their therapeutic importance, the structural mechanism of GPCR signaling is of great interest in the field of drug discovery. Hydrogen/deuterium exchange mass spectrometry (HDX-MS) is a useful tool for analyzing ligand binding sites, the protein-protein interaction interface, and conformational changes of proteins. However, its application to GPCRs has been limited for various reasons, including the hydrophobic nature of GPCRs and the use of detergents in their preparation. In the present study, we tested the application of bicelles as a means of solubilizing GPCRs for HDX-MS studies. GPCRs (e.g., ?2-adrenergic receptor [?2AR], ?-opioid receptor, and protease-activated receptor 1) solubilized in bicelles produced better sequence coverage (greater than 90%) than GPCRs solubilized in n-dodecyl-?-D-maltopyranoside (DDM), suggesting that bicelles are a more effective method of solubilization for HDX-MS studies. The HDX-MS profile of ?2AR in bicelles showed that transmembrane domains (TMs) undergo lower deuterium uptake than intracellular or extracellular regions, which is consistent with the fact that the TMs are highly ordered and embedded in bicelles. The overall HDX-MS profiles of ?2AR solubilized in bicelles and in DDM were similar except for intracellular loop 3. Interestingly, we detected EX1 kinetics, an important phenomenon in protein dynamics, at the C-terminus of TM6 in ?2AR. In conclusion, we suggest the application of bicelles as a useful method for solubilizing GPCRs for conformational analysis by HDX-MS.

Duc, Nguyen Minh; Du, Yang; Thorsen, Thor S.; Lee, Su Youn; Zhang, Cheng; Kato, Hideaki; Kobilka, Brian K.; Chung, Ka Young

2015-03-01

185

Effective application of bicelles for conformational analysis of g protein-coupled receptors by hydrogen/deuterium exchange mass spectrometry.  

PubMed

G protein-coupled receptors (GPCRs) have important roles in physiology and pathology, and 40% of drugs currently on the market target GPCRs for the treatment of various diseases. Because of their therapeutic importance, the structural mechanism of GPCR signaling is of great interest in the field of drug discovery. Hydrogen/deuterium exchange mass spectrometry (HDX-MS) is a useful tool for analyzing ligand binding sites, the protein-protein interaction interface, and conformational changes of proteins. However, its application to GPCRs has been limited for various reasons, including the hydrophobic nature of GPCRs and the use of detergents in their preparation. In the present study, we tested the application of bicelles as a means of solubilizing GPCRs for HDX-MS studies. GPCRs (e.g., ?2-adrenergic receptor [?2AR], ?-opioid receptor, and protease-activated receptor 1) solubilized in bicelles produced better sequence coverage (greater than 90%) than GPCRs solubilized in n-dodecyl-?-D-maltopyranoside (DDM), suggesting that bicelles are a more effective method of solubilization for HDX-MS studies. The HDX-MS profile of ?2AR in bicelles showed that transmembrane domains (TMs) undergo lower deuterium uptake than intracellular or extracellular regions, which is consistent with the fact that the TMs are highly ordered and embedded in bicelles. The overall HDX-MS profiles of ?2AR solubilized in bicelles and in DDM were similar except for intracellular loop 3. Interestingly, we detected EX1 kinetics, an important phenomenon in protein dynamics, at the C-terminus of TM6 in ?2AR. In conclusion, we suggest the application of bicelles as a useful method for solubilizing GPCRs for conformational analysis by HDX-MS. PMID:25740347

Duc, Nguyen Minh; Du, Yang; Thorsen, Thor S; Lee, Su Youn; Zhang, Cheng; Kato, Hideaki; Kobilka, Brian K; Chung, Ka Young

2015-05-01

186

Characterization of IgG1 Conformation and Conformational Dynamics by Hydrogen/Deuterium Exchange Mass Spectrometry  

SciTech Connect

Protein function is dictated by protein conformation. For the protein biopharmaceutical industry, therefore, it is important to have analytical tools that can detect changes in protein conformation rapidly, accurately, and with high sensitivity. In this paper we show that hydrogen/deuterium exchange mass spectrometry (H/DX-MS) can play an important role in fulfilling this need within the industry. H/DX-MS was used to assess both global and local conformational behavior of a recombinant monoclonal IgG1 antibody, a major class of biopharmaceuticals. Analysis of exchange into the intact, glycosylated IgG1 (and the Fab and Fc regions thereof) showed that the molecule was folded, highly stable, and highly amenable to analysis by this method using less than a nanomole of material. With improved chromatographic methods, peptide identification algorithms and data-processing steps, the analysis of deuterium levels in peptic peptides produced after labeling was accomplished in 1--2 days. On the basis of peptic peptide data, exchange was localized to specific regions of the antibody. Changes to IgG1 conformation as a result of deglycosylation were determined by comparing exchange into the glycosylated and deglycosylated forms of the antibody. Two regions of the IgG1 (residues 236-253 and 292-308) were found to have altered exchange properties upon deglycosylation. These results are consistent with previous findings concerning the role of glycosylation in the interaction of IgG1 with Fc receptors. Moreover, the data clearly illustrate how H/DX-MS can provide important characterization information on the higher order structure of antibodies and conformational changes that these molecules may experience upon modification.

Houde, Damian; Arndt, Joseph; Domeier, Wayne; Berkowitz, Steven; Engen, John R.; (NEU); (Biogen)

2009-04-22

187

Patterns of structural dynamics in RACK1 protein retained throughout evolution: a hydrogen-deuterium exchange study of three orthologs.  

PubMed

RACK1 is a member of the WD repeat family of proteins and is involved in multiple fundamental cellular processes. An intriguing feature of RACK1 is its ability to interact with at least 80 different protein partners. Thus, the structural features enabling such interactomic flexibility are of great interest. Several previous studies of the crystal structures of RACK1 orthologs described its detailed architecture and confirmed predictions that RACK1 adopts a seven-bladed ?-propeller fold. However, this did not explain its ability to bind to multiple partners. We performed hydrogen-deuterium (H-D) exchange mass spectrometry on three orthologs of RACK1 (human, yeast, and plant) to obtain insights into the dynamic properties of RACK1 in solution. All three variants retained similar patterns of deuterium uptake, with some pronounced differences that can be attributed to RACK1's divergent biological functions. In all cases, the most rigid structural elements were confined to B-C turns and, to some extent, strands B and C, while the remaining regions retained much flexibility. We also compared the average rate constants for H-D exchange in different regions of RACK1 and found that amide protons in some regions exchanged at least 1000-fold faster than in others. We conclude that its evolutionarily retained structural architecture might have allowed RACK1 to accommodate multiple molecular partners. This was exemplified by our additional analysis of yeast RACK1 dimer, which showed stabilization, as well as destabilization, of several interface regions upon dimer formation. PMID:24591271

Tarnowski, Krzysztof; Fituch, Kinga; Szczepanowski, Roman H; Dadlez, Michal; Kaus-Drobek, Magdalena

2014-05-01

188

Carbon assisted water electrolysis for hydrogen generation  

NASA Astrophysics Data System (ADS)

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.

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

2013-06-01

189

Confinement of hydrogen at high pressure in carbon nanotubes  

DOEpatents

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.

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

2011-12-13

190

The effect of a nitrogen-rich surface layer on the sub-surface deuterium (hydrogen) concentration distribution in titanium  

NASA Astrophysics Data System (ADS)

Deuterium and nitrogen depth profiles in Ti with modified surfaces have been measured with Auger electron spectroscopy, secondary ion mass spectroscopy, and D( 3He,p) 4He nuclear reaction analysis. Nitrogen-rich surfaces layers of varying thicknesses were created on Ti by exposure to N 2 gas at 650°C. Deuterium loading was performed by exposure to 1 Torr of D 2 gas at 500°C. The deuterium distribution was influenced by nitrogen in the near-surface regions of all samples. Specifically, deuterium solubility was suppressed in surface regions of high (greater than 1%) nitrogen concentration. The deuterium solubility also remained low within the first few microns, well beyond the region of high nitrogen concentration. This effect is attributed to internal elastic stresses imposed by the non-deuterium absorbing nitrogen-rich layer on the Ti. These stresses prohibit the volume expansion associated with deuterium absorption. We estimate stresses on the order of 3-4 GPa are required to suppress the deuterium solubility to the values observed. The deuterium absorption kinetics were observed to depend systematically on the thickness of the nitrogen-rich layer. This is consistent with limited solubility near the surface or a surface poisoning effect influencing the overall deuterium diffusion from the gas phase into the Ti bulk.

Costescu, Corneliu I.; Heuser, Brent J.

2000-04-01

191

Carbon-hydrogen to carbon-phosphorus transformations.  

PubMed

Literature published between 2008 and 2013 concerning the functionalization of carbon-hydrogen into carbon-phosphorus bonds is surveyed. The chapter is organized by reaction mechanism. The majority of methods still proceed via deprotonation of C-H into C-M (M=Li, Na, etc.) followed by reaction with a phosphorus electrophile P-X, where X is usually chlorine. A few examples of electrophilic aromatic substitution and related processes have also been reported, although this approach has not yet been developed significantly. Over the past 5 years a rapidly growing family of reactions includes transition metal "C-H activation" and formally related radical-based processes has been developed. The latter processes offer exciting prospects for the synthesis of organophosphorus compounds. PMID:25370519

Montchamp, Jean-Luc

2015-01-01

192

IUE observations of interstellar hydrogen and deuterium toward Alpha Centauri B  

NASA Technical Reports Server (NTRS)

A high dispersion profile is presented of the Lyman-alpha emission toward Alpha Cen B as recorded in two images taken with the IUE spacecraft. The spectra were examined with a three-parameter Gaussian or five-parameter solar-type profile to derive the intrinsic background stellar emission. Voight absorption profiles were calculated for the intervening H I and D I gas. A uniform, thermally broadened medium was assumed, with the calculations being based on the free stellar parameters of density, velocity dispersion and the bulk velocity of H I, and the density of D I. The use of a small aperture is shown to have been effective in eliminating geocoronal and interplanetary diffuse Ly-alpha contamination. The H I absorption profile toward Alpha Cen B is found to be equivalent to that toward Alpha Cen A, indicating that the H I profiles derived are essentially independent of stellar emission. Less success, however, was attained in obtaining any definitive D I profile, although an asymmetry in the blue and red wings of the Lyman-alpha emissions did show the presence of absorption by interstellar deuterium and allow setting a lower limit of 0.00001 for the D I/H I ratio.

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

1986-01-01

193

FeTiMn alloy granulate in a pressure container for storage of hydrogen and deuterium  

Microsoft Academic Search

Oxygen is incorporated into an FeTiMn granulate in an amount sufficient to form double oxides of titanium and manganese therein, but insufficient to form oxides containing iron. As the result, the granules are embrittled, favoring the formation of microcracks to such an extent that activation of the granules by hydrogen takes place, after initial evacuation, at room temperature, after which

K. Klatt; H. Wenzl

1982-01-01

194

Carbonate thermochemical cycle for the production of hydrogen  

DOEpatents

The present invention is directed to a thermochemical method for the production of hydrogen from water. The method includes reacting a multi-valent metal oxide, water and a carbonate to produce an alkali metal-multi-valent metal oxide compound, carbon dioxide, and hydrogen.

Collins, Jack L (Knoxville, TN) [Knoxville, TN; Dole, Leslie R (Knoxville, TN) [Knoxville, TN; Ferrada, Juan J (Knoxville, TN) [Knoxville, TN; Forsberg, Charles W (Oak Ridge, TN) [Oak Ridge, TN; Haire, Marvin J (Oak Ridge, TN) [Oak Ridge, TN; Hunt, Rodney D (Oak Ridge, TN) [Oak Ridge, TN; Lewis Jr., Benjamin E (Knoxville, TN) [Knoxville, TN; Wymer, Raymond G (Oak Ridge, TN) [Oak Ridge, TN

2010-02-23

195

Review of hydrogen storage by adsorption in carbon nanotubes  

Microsoft Academic Search

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

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

2002-01-01

196

Hydrogen Storage on Metal-Doped Ordered Mesoporous Carbons  

E-print Network

Hydrogen Storage on Metal-Doped Ordered Mesoporous Carbons Shuguang Deng New Mexico State Meeting, May 18, 2010 #12;Outline · Research group · Hydrogen storage: background and status · Synthesis of pure and metal-doped OMC · Characterization of metal-doped OMC · Hydrogen adsorption equilibrium

Johnson, Eric E.

197

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

Microsoft Academic Search

The recent application of electron transfer dissociation (ETD) to measure the hydrogen exchange of proteins in solution at\\u000a single-residue resolution (HX-ETD) paves the way for mass spectrometry-based analyses of biomolecular structure at an unprecedented\\u000a level of detail. The approach requires that activation of polypeptide ions prior to ETD is minimal so as to prevent undesirable\\u000a gas-phase randomization of the deuterium

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

198

Characterization of the interface structure of enzyme-inhibitor complex by using hydrogen-deuterium exchange and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry.  

PubMed Central

We investigated the interaction between a thiol protease inhibitor, cystatin, and its target enzyme, papain, by hydrogen-deuterium (H/D) exchange in conjunction with successive analysis by collision-induced dissociation (CID) in an rf-only hexapole ion guide with electrospray ionization-Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR MS). The deuterium incorporation into backbone amide hydrogens of cystatin was analyzed at different time points in the presence or absence of papain, examining the mass of each fragment produced by hexapole-CID. In the absence of papain, amide hydrogens in short amino-terminal fragments, such as b10(2+) and b12(2+), were highly deuterated within 1 min. Although fewer fragments were observed for the cystatin-papain complex in the hexapole-CID spectra, significant reductions in initial deuterium content were recognized throughout the sequence of cystatin. This suggests that complex formation restricted the flexibility of the whole cystatin molecule. Detailed analyses revealed that a marked reduction in deuterium content in the region of residues 1-10 persisted for hours, suggesting that the flexible N-terminal region was tightly fixed in the binding pocket with hydrogen bonds. Our results are consistent with those of previous studies on the structure and inhibition mechanism of cystatin. We demonstrated here that enzyme-inhibitor interactions can be characterized by H/D exchange in combination with CID in a hexapole ion guide using ESI-FTICR MS rapidly and using only a small amount of sample. PMID:11206071

Akashi, S.; Takio, K.

2000-01-01

199

Gas phase hydrogen deuterium exchange reactions of a model peptide: FT-ICR and computational analyses of metal induced conformational mutations  

Microsoft Academic Search

We utilized gas phase hydrogen\\/deuterium (H\\/D) exchange reactions and ab initio calculations to investigate the complexation\\u000a between a model peptide (Arg-Gly-Asp?RGD) with various alkali metal ions. The peptide conformation is drastically altered\\u000a upon alkali metal ion complexation. The associated conformational changes depend on both the number and type of complexing\\u000a alkali metal ions. Sodium has a smaller ionic diameter and

T. Solouki; R. C. Fort; A. Alomary; A. Fattahi

2001-01-01

200

Vacuum ultraviolet photolysis of hydrogenated amorphous carbons . I. Interstellar H2 and CH4 formation rates  

NASA Astrophysics Data System (ADS)

Context. The interstellar hydrogenated amorphous carbons (HAC or a-C:H) observed in the diffuse medium are expected to disappear in a few million years, according to the destruction time scale from laboratory measurements. The existence of a-C:H results from the equilibrium between photodesorption, radiolysis, hydrogenation and resilience of the carbonaceous network. During this processing, many species are therefore injected into the gas phase, in particular H2, but also small organic molecules, radicals or fragments. Aims: We perform experiments on interstellar a-C:H analogs to quantify the release of these species in the interstellar medium. Methods: The vacuum ultraviolet (VUV) photolysis of interstellar hydrogenated amorphous carbon analogs was performed at low (10 K) to ambient temperature, coupled to mass-spectrometry detection and temperature-programed desorption. Using deuterium isotopic substitution, the species produced were unambiguously separated from background contributions. Results: The VUV photolysis of hydrogenated amorphous carbons leads to the efficient production of H2 molecules, but also to small hydrocarbons. Conclusions: These species are formed predominantly in the bulk of the a-C:H analog carbonaceous network, in addition to the surface formation. Compared with species made by the recombination of H atoms and physisorbed on surfaces, they diffuse out at higher temperatures. In addition to the efficient production rate, it provides a significant formation route in environments where the short residence time scale for H atoms inhibits H2 formation on the surface, such as PDRs. The photolytic bulk production of H2 with carbonaceous hydrogenated amorphous carbon dust grains can provide a very large portion of the contribution to the H2 molecule formation. These dust grains also release small hydrocarbons (such as CH4) into the diffuse interstellar medium, which contribute to the formation of small carbonaceous radicals after being dissociated by the UV photons in the considered environment. This extends the interstellar media environments where H2 and small hydrocarbons can be produced.

Alata, I.; Cruz-Diaz, G. A.; Muñoz Caro, G. M.; Dartois, E.

2014-09-01

201

Adsorptive hydrogen storage in carbon and porous materials  

Microsoft Academic Search

The hydrogen adsorption and desorption isotherms of a highly pure single-walled carbon nanotube sample (SWCNT), a corresponding nitric acid-treated sample (A-SWCNT), two zeolites, and several kinds of activated carbon fibers (ACFs) were measured at 77 and 303K over the hydrogen pressure range 0–3.5MPa by using the high-pressure adsorption apparatus with sufficient accuracy. The amount of adsorbed hydrogen by weight depended

H. Takagi; H. Hatori; Y. Soneda; N. Yoshizawa; Y. Yamada

2004-01-01

202

Caustic-impregnated activated carbons for removal of hydrogen sulfide  

SciTech Connect

This paper describes improvement in a process for removing hydrogen sulfide from an oxygen-containing gas stream by passing the gas stream through caustic-impregnated activated carbon, the stream containing from about 5 ppm to about 10,000 ppm by volume of hydrogen sulfide. The improvement comprises: the breakthrough capacity of the caustic-impregnated activated carbon for hydrogen sulfide is extended by the addition of ammonia to the gas stream about the time of breakthrough.

Truk, A.

1991-06-18

203

Caustic-impregnated activated carbons for removal of hydrogen sulfide  

Microsoft Academic Search

This paper describes improvement in a process for removing hydrogen sulfide from an oxygen-containing gas stream by passing the gas stream through caustic-impregnated activated carbon, the stream containing from about 5 ppm to about 10,000 ppm by volume of hydrogen sulfide. The improvement comprises: the breakthrough capacity of the caustic-impregnated activated carbon for hydrogen sulfide is extended by the addition

Truk

1991-01-01

204

Applications of nuclear reaction analysis for determining hydrogen and deuterium distribution in metals  

SciTech Connect

The use of ion beams for materials analysis has made a successful transition from the domain of the particle physicist to that of the materials scientist. The subcategory of this field, nuclear reaction analysis, is just now undergoing the transition, particularly in applications to hydrogen in materials. The materials scientist must locate the nearest accelerator, because now he will find that using it can solve mysteries that do not yield to other techniques. 9 figures

Altstetter, C.J.

1981-01-01

205

EXCHANGE OF DEUTERIUM AND HEAVY OXYGEN AMONG HYDROGEN, WATER VAPOR AND OXIDE CATALYSTS OF SPINEL TYPE  

Microsoft Academic Search

The exchange of D and O¹⁸ among Hâ, DâO¹⁸, and ; oxide catalysts of the spinel type, MgAlâOâ, MgCrâOâ, ; ZnCrâOâ, and ZnFeâOâ was studied by a flow method. The ; total ex- . change rate of hydrogen, R, and that of oxygen, R, were calculated. ; R'\\/R of a catalyst was found to be approximately independent of temperature and

Y. Yoneda; A. Fujimoto; S. Makishima

1959-01-01

206

Activity-regulating structural changes and autoantibody epitopes in transglutaminase 2 assessed by hydrogen/deuterium exchange  

PubMed Central

The multifunctional enzyme transglutaminase 2 (TG2) is the target of autoantibodies in the gluten-sensitive enteropathy celiac disease. In addition, the enzyme is responsible for deamidation of gluten peptides, which are subsequently targeted by T cells. To understand the regulation of TG2 activity and the enzyme’s role as an autoantigen in celiac disease, we have addressed structural properties of TG2 in solution by using hydrogen/deuterium exchange monitored by mass spectrometry. We demonstrate that Ca2+ binding, which is necessary for TG2 activity, induces structural changes in the catalytic core domain of the enzyme. Cysteine oxidation was found to abolish these changes, suggesting a mechanism whereby disulfide bond formation inactivates the enzyme. Further, by using TG2-specific human monoclonal antibodies generated from intestinal plasma cells of celiac disease patients, we observed that binding of TG2 by autoantibodies can induce structural changes that could be relevant for the pathogenesis. Detailed mapping of two of the main epitopes targeted by celiac disease autoantibodies revealed that they are located adjacent to each other in the N-terminal part of the TG2 molecule. PMID:25404341

Iversen, Rasmus; Mysling, Simon; Hnida, Kathrin; Jørgensen, Thomas J. D.; Sollid, Ludvig M.

2014-01-01

207

Mapping residual structure in intrinsically disordered proteins at residue resolution using millisecond hydrogen/deuterium exchange and residue averaging.  

PubMed

Measurement of residual structure in intrinsically disordered proteins can provide insights into the mechanisms by which such proteins undergo coupled binding and folding. The present work describes an approach to measure residual structure in disordered proteins using millisecond hydrogen/deuterium (H/D) exchange in a conventional bottom-up peptide-based workflow. We used the exchange mid-point, relative to a totally deuterated control, to quantify the rate of H/D exchange in each peptide. A weighted residue-by-residue average of these midpoints was used to map the extent of residual structure at near single-residue resolution. We validated this approach both by simulating a disordered protein and experimentally using the p300 binding domain of ACTR, a model disordered protein already well-characterized by other approaches. Secondary structure elements mapped in the present work are in good agreement with prior nuclear magnetic resonance measurements. The new approach was somewhat limited by a loss of spatial resolution and subject to artifacts because of heterogeneities in intrinsic exchange. Approaches to correct these limitations are discussed. PMID:25481641

Keppel, Theodore R; Weis, David D

2015-04-01

208

Mapping Residual Structure in Intrinsically Disordered Proteins at Residue Resolution Using Millisecond Hydrogen/Deuterium Exchange and Residue Averaging  

NASA Astrophysics Data System (ADS)

Measurement of residual structure in intrinsically disordered proteins can provide insights into the mechanisms by which such proteins undergo coupled binding and folding. The present work describes an approach to measure residual structure in disordered proteins using millisecond hydrogen/deuterium (H/D) exchange in a conventional bottom-up peptide-based workflow. We used the exchange mid-point, relative to a totally deuterated control, to quantify the rate of H/D exchange in each peptide. A weighted residue-by-residue average of these midpoints was used to map the extent of residual structure at near single-residue resolution. We validated this approach both by simulating a disordered protein and experimentally using the p300 binding domain of ACTR, a model disordered protein already well-characterized by other approaches. Secondary structure elements mapped in the present work are in good agreement with prior nuclear magnetic resonance measurements. The new approach was somewhat limited by a loss of spatial resolution and subject to artifacts because of heterogeneities in intrinsic exchange. Approaches to correct these limitations are discussed.

Keppel, Theodore R.; Weis, David D.

2015-04-01

209

Proton nuclear magnetic resonance spectroscopy of human transferrin N-terminal half-molecule: titration and hydrogen-deuterium exchange  

SciTech Connect

The binding of Ga(III) to the proteolytically derived N-terminal half-molecule of human transferrin (HTF/2N) was studied by proton nuclear magnetic resonance spectroscopy. The pH-dependent titration curves of the histidinyl C(2) proton chemical shifts were altered upon formation of the GaIIIHTF/2N(C/sub 2/O/sub 4/) ternary complex. Two high-pK'a histidines failed to titrate when the metal and synergistic anion formed a complex with the protein. These results implicated two histidinyl residues as direct ligands to the metal. The rates of hydrogen-deuterium exchange for the C(2) protons of certain histidinyl residues were substantially decreased by metal ion binding. The two ligand histidines were protected from exchange, and a third, low-pK'a, histidinyl residue was protected. We propose that this third histidinyl residue is involved in anion binding and may serve as the base in the putative proton-relay scheme proposed for complex formation.

Valcour, A.A.; Woodworth, R.C.

1987-06-02

210

Different conformational dynamics of ?-arrestin1 and ?-arrestin2 analyzed by hydrogen/deuterium exchange mass spectrometry.  

PubMed

Arrestins have important roles in G protein-coupled receptor (GPCR) signaling including desensitization of GPCRs and G protein-independent signaling. There have been four arrestins identified: arrestin1, arrestin2 (e.g. ?-arrestin1), arrestin3 (e.g. ?-arrestin2), and arrestin4. ?-Arrestin1 and ?-arrestin2 are ubiquitously expressed and regulate a broad range of GPCRs, while arrestin1 and arrestin4 are expressed in the visual system. Although the functions of ?-arrestin1 and ?-arrestin2 widely overlap, ?-arrestin2 has broader receptor selectivity, and a few studies have suggested that ?-arrestin1 and ?-arrestin2 have distinct cellular functions. Here, we compared the conformational dynamics of ?-arrestin1 and ?-arrestin2 by hydrogen/deuterium exchange mass spectrometry (HDX-MS). We also used the R169E mutant as a pre-activation model system. HDX-MS data revealed that ?-strands II through IV were more dynamic in ?-arrestin2 in the basal state, while the middle loop was more dynamic in ?-arrestin1. With pre-activation, both ?-arrestin1 and ?-arrestin2 became more flexible, but broader regions of ?-arrestin1 became flexible compared to ?-arrestin2. The conformational differences between ?-arrestin1 and ?-arrestin2 in both the basal and pre-activated states might determine their different receptor selectivities and different cellular functions. PMID:25542150

Yun, Youngjoo; Kim, Dong Kyun; Seo, Min-Duk; Kim, Kyeong-Man; Chung, Ka Young

2015-01-30

211

Characterization of Stress-Exposed Granulocyte Colony Stimulating Factor Using ELISA and Hydrogen/Deuterium Exchange Mass Spectrometry  

NASA Astrophysics Data System (ADS)

Information on the higher-order structure is important in the development of biopharmaceutical drugs. Recently, hydrogen/deuterium exchange coupled with mass spectrometry (HDX-MS) has been widely used as a tool to evaluate protein conformation, and unique automated systems for HDX-MS are now commercially available. To investigate the potential of this technique for the prediction of the activity of biopharmaceuticals, granulocyte colony stimulating factor (G-CSF), which had been subjected to three different stress types, was analyzed using HDX-MS and through comparison with receptor-binding activity. It was found that HDX-MS, in combination with ion mobility separation, was able to identify conformational changes in G-CSF induced by stress, and a good correlation with the receptor-binding activity was demonstrated, which cannot be completely determined by conventional peptide mapping alone. The direct evaluation of biological activity using bioassay is absolutely imperative in biopharmaceutical development, but HDX-MS can provide the alternative information in a short time on the extent and location of the structural damage caused by stresses. Furthermore, the present study suggests the possibility of this system being a versatile evaluation method for the preservation stability of biopharmaceuticals.

Tsuchida, Daisuke; Yamazaki, Katsuyoshi; Akashi, Satoko

2014-10-01

212

NMR-Based Amide Hydrogen-Deuterium Exchange Measurements for Complex Membrane Proteins: Development and Critical Evaluation  

NASA Astrophysics Data System (ADS)

A method for measuring site-specific amide hydrogen-deuterium exchange rates for membrane proteins in bilayers is reported and evaluated. This method represents an adaptation and extension of the approach of Dempsey and co-workers ( Biophys. J. 70, 1777-1788 (1996)) and is based on reconstituting 15N-labeled membrane proteins into phospholipid bilayers, followed by lyophilization and rehydration with D 2O or H 2O (control). Following incubation for a time t under hydrated conditions, samples are again lyophilized and then solubilized in an organic solvent system, where 1H- 15N HSQC spectra are recorded. Comparison of spectra from D 2O-exposed samples to spectra from control samples yields the extent of the H-D exchange which occurred in the bilayers during time t. Measurements are site specific if specific 15N labeling is used. The first part of this paper deals with the search for a suitable solvent system in which to solubilize complex membrane proteins in an amide "exchange-trapped" form for NMR quantitation of amide peak intensities. The second portion of the paper documents application of the overall procedure to measuring site-specific amide exchange rates in diacylglycerol kinase, a representative integral membrane protein. Both the potential usefulness and the significant limitations of the new method are documented.

Czerski, Lech; Vinogradova, Olga; Sanders, Charles R.

2000-01-01

213

Effect of deuterium substitution for hydrogen in surface functionalisation of hydrophilic nanosilicon particles on their spectral and dynamic properties  

NASA Astrophysics Data System (ADS)

Broadband femtosecond spectroscopy has been used to study two types of hydrophilic silicon nanoparticles: (1) photoluminescent, passivated with deuterium and oxidised in fully deuterated dimethyl sulphoxide, and (2) nonluminescent (control samples having a similar crystalline core), passivated with hydrogen and oxidised in dimethyl sulphoxide. We have found significant differences in ultrafast spectral - temporal induced absorption dynamics between the two types of nanoparticles in the energy range corresponding to their calculated band gap. The observed distinction is due to the considerably higher oxidation rate of silicon on the surface of the deuterated samples in comparison with the undeuterated ones and with the associated increase in the number of photoluminescence centres on the surface of the nanoparticles. In the samples containing self-trapped exciton (STE) energy states responsible for the photoluminescence in the red spectral region, carrier capture at these levels and carrier relaxation to the ground state have characteristic times in the femtosecond range. In the samples free of STE states, excited carriers relax to the conduction band bottom in a characteristic time of several picoseconds.

Kompanets, V. O.; Chekalin, S. V.; Dorofeev, S. G.; Kononov, N. N.; Barzilovich, P. Yu; Ishchenko, A. A.

2014-06-01

214

DEVELOPMENT OF DOPED NANOPOROUS CARBONS FOR HYDROGEN STORAGE  

SciTech Connect

Hydrogen storage materials based on the hydrogen spillover mechanism onto metal-doped nanoporous carbons are studied, in an effort to develop materials that store appreciable hydrogen at ambient temperatures and moderate pressures. We demonstrate that oxidation of the carbon surface can significantly increase the hydrogen uptake of these materials, primarily at low pressure. Trace water present in the system plays a role in the development of active sites, and may further be used as a strategy to increase uptake. Increased surface density of oxygen groups led to a significant enhancement of hydrogen spillover at pressures less than 100 milibar. At 300K, the hydrogen uptake was up to 1.1 wt. % at 100 mbar and increased to 1.4 wt. % at 20 bar. However, only 0.4 wt% of this was desorbable via a pressure reduction at room temperature, and the high lowpressure hydrogen uptake was found only when trace water was present during pretreatment. Although far from DOE hydrogen storage targets, storage at ambient temperature has significant practical advantages oner cryogenic physical adsorbents. The role of trace water in surface modification has significant implications for reproducibility in the field. High-pressure in situ characterization of ideal carbon surfaces in hydrogen suggests re-hybridization is not likely under conditions of practical interest. Advanced characterization is used to probe carbon-hydrogen-metal interactions in a number of systems and new carbon materials have been developed.

Angela D. Lueking; Qixiu Li; John V. Badding; Dania Fonseca; Humerto Gutierrez; Apurba Sakti; Kofi Adu; Michael Schimmel

2010-03-31

215

Hydrogen/deuterium exchange-protected oligomers populated during A? fibril formation correlate with neuronal cell death.  

PubMed

The aggregation of the amyloid-? peptide (A?) to form fibrils and plaques is strongly associated with Alzheimer's disease (AD). Although it is well established that this process generates neurotoxicity, it is also heterogeneous with a variety of species being formed during the conversion process. This heterogeneity makes it difficult to detect and characterize each of the aggregates formed, which precludes establishing the specific features responsible for the neurotoxicity observed. Here we use pulse-labeling hydrogen-deuterium exchange experiments analyzed by electrospray ionization mass spectrometry (PL-HDX-ESI-MS) to distinguish three ensembles populated during the aggregation of the 40 and 42 residue forms of the A? peptide, A?40 and A?42, on the basis of differences in their persistent structure. Noticeably, two of them are more abundant at the beginning and at the end of the lag phase and are therefore not detectable by conventional assays such as Thioflavin T (ThT). The ensembles populated at different stages of the aggregation process have a surprisingly consistent average degree of exchange, indicating that there are definite structural transitions between the different stages of aggregation. To determine whether an ensemble of species with a given hydrogen exchange pattern correlates with neurotoxicity, we combined PL-HDX-ESI-MS experiments with parallel measurements of the neurotoxicity of the samples under study. The results of this dual approach show that the maximum toxicity correlates with the ensemble comprising HDX protected oligomers, indicating that development of persistent structure within A? oligomers is a determinant of neurotoxicity. PMID:25265274

Serra-Vidal, Bernat; Pujadas, Lluís; Rossi, Daniela; Soriano, Eduardo; Madurga, Sergio; Carulla, Natàlia

2014-11-21

216

Effects of hydrogen adsorption on single-wall carbon nanotubes: Metallic hydrogen decoration O. Gulseren,1,2  

E-print Network

Effects of hydrogen adsorption on single-wall carbon nanotubes: Metallic hydrogen decoration O. Gu of carbon nanotubes undergo dramatic changes with hydrogen chemisorption from first principle calculations other isomers can be insulating. For both zigzag and armchair nanotubes, hydrogenation of each carbon

Yildirim, Taner

217

Fundamentals and applications of the hydrogen\\/deuterium isotope effect in improved hot-carrier reliability of MOS devices  

Microsoft Academic Search

The reliability due to hot-carrier effects poses increasing constraints on the downscaling of CMOS transistors. This thesis attempts to provide a thorough study on both fundamentals and applications of enhancing CMOS reliability by incorporation of deuterium at the oxide\\/silicon interface. The impacts of the high pressure deuterium process on device characteristics and reliability are first investigated. The effectiveness of the

Kangguo Cheng

2001-01-01

218

Sticking coefficient of hydrogen and deuterium on silicates under interstellar conditions  

E-print Network

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...

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

2012-01-01

219

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

NASA Astrophysics Data System (ADS)

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).

Gerst, Steve; Quay, Paul

2000-11-01

220

UV pumping of hyperfine transitions in the light elements, with application to 21-cm hydrogen and 92-cm deuterium lines from the early universe  

E-print Network

We present new analytic calculations of the coupling between ultraviolet resonance photons and the population of the hyperfine states in the light elements (H, D, He3+) which include several previously neglected physical processes. Among these are the backreaction of resonant scattering on the pumping radiation, the scattering of Ly_beta photons and the effect of local departure from pure Hubble flow. The application of the new treatment to the redshifted hydrogen 21 and deuterium 92 cm lines from the high-redshift universe results in an amplitude correction of up to an order of magnitude. We further show that the standard assumption that ultraviolet pumping drives the spin temperature towards the kinetic temperature does not hold for deuterium, whose spin temperature is generally negative.

Leonid Chuzhoy; Paul R. Shapiro

2006-06-30

221

Hydrogen-deuterium exchange of diborane in superacid solution through diboranonium (B sub 2 H sub 7 sup + ) and diboranium (B sub 2 H sub 5 sup + ) ions  

SciTech Connect

The slow proton/deuterium exchange of B{sub 2}H{sub 6} in the superacidic FSO{sub 3}D SbF{sub 5}/SO{sub 2}ClF medium at low temperature involving the corresponding isotopomeric diboranonium ions B{sub 2}H{sub 7}{sup +} is reported here. The structure of the B{sub 2}H{sub 7}{sup +} ion has also been probed by ab inito theoretical calculations. The H/D exchange is rationalized by the pathway that deuteriation occurs exclusively on an unbridged (terminal B-H) bond resulting in a B{sub 2}H{sub 6}D{sup +} ion which is expected to undergo polytopol (bond-to-bond) rearrangement scrambling all hydrogens and deuteriums followed by proton loss leading to the exchanged product. 18 references.

Olah, G.A.; Aniszfeld, R.; Surya Prakash, G.K.; Williams, R.E.; Lammertsma, K.; Guener, O.F.

1988-11-09

222

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

NASA Astrophysics Data System (ADS)

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 13C in groundwater pollutants in aquifers. It is also suggested that deuterium shifts are expected to be higher, especially for strongly sorbing pollutants.

Höhener, Patrick; Yu, Xianjing

2012-03-01

223

Conformational Difference in Human IgG2 Disulfide Isoforms Revealed by Hydrogen/Deuterium Exchange Mass Spectrometry.  

PubMed

Both recombinant and natural human IgG2 antibodies have several different disulfide bond isoforms, which possess different global structures, thermal stabilities, and biological activities. A detailed mapping of the structural difference among IgG2 disulfide isoforms, however, has not been established. In this work, we employed hydrogen/deuterium exchange mass spectrometry to study the conformation of three major IgG2 disulfide isoforms known as IgG2-B, IgG2-A1, and IgG2-A2 in two recombinant human IgG2 monoclonal antibodies. By comparing the protection factors between amino acid residues in isoforms B and A1 (the classical form), we successfully identified several local regions in which the IgG2-B isoform showed more solvent protection than the IgG2-A1 isoform. On the basis of three-dimensional structural models of IgG2, these identified regions were located on the Fab domains, close to the hinge, centered on the side where the two Fab arms faced each other in spatial proximity. We speculated that in the more solvent-protected B isoform, the two Fab arms were brought into contact by the nonclassical disulfide bonds, resulting in a more compact global structure. Loss of Fab domain flexibility in IgG2-B could limit its ability to access cell-surface epitopes, leading to reduced antigen binding potency. The A2 isoform was previously found to have disulfide linkages similar to those of the classical A1 isoform, but with different biophysical behaviors. Our data indicated that, compared to IgG2-A1, IgG2-A2 had less solvent protection in some heavy-chain Fab regions close the hinge, suggesting that the A2 isoform had more flexible Fab domains. PMID:25730439

Zhang, Aming; Fang, Jing; Chou, Robert Y-T; Bondarenko, Pavel V; Zhang, Zhongqi

2015-03-17

224

Molecular hydrogen tweezers: structure and mechanisms by neutron diffraction, NMR, and deuterium labeling studies in solid and solution.  

PubMed

The mechanism of reversible hydrogen activation by ansa-aminoboranes, 1-N-TMPH-CH(2)-2-[HB(C(6)F(5))(2)]C(6)H(4) (NHHB), was studied by neutron diffraction and thermogravimetric mass-spectroscopic experiments in the solid state as well as with NMR and FT-IR spectroscopy in solution. The structure of the ansa-ammonium borate NHHB was determined by neutron scattering, revealing a short N-H···H-B dihydrogen bond of 1.67 Å. Moreover, this intramolecular H-H distance was determined in solution to be also 1.6-1.8 Å by (1)H NMR spectroscopic T(1) relaxation and 1D NOE measurements. The X-ray B-H and N-H distances deviated from the neutron and the calculated values. The dynamic nature of the molecular tweezers in solution was additionally studied by multinuclear and variable-temperature NMR spectroscopy. We synthesized stable, individual isotopic isomers NDDB, NHDB, and NDHB. NMR measurements revealed a primary isotope effect in the chemical shift difference (p)?(1)H(D) = ?(NH) - ?(ND) (0.56 ppm), and hence supported dihydrogen bonding. The NMR studies gave strong evidence that the structure of NHHB in solution is similar to that in the solid state. This is corroborated by IR studies providing clear evidence for the dynamic nature of the intramolecular dihydrogen bonding at room temperature. Interestingly, no kinetic isotope effect was detected for the activation of deuterium hydride by the ansa-aminoborane NB. Theoretical calculations attribute this to an "early transition state". Moreover, 2D NOESY NMR measurements support fast intermolecular proton exchange in aprotic CD(2)Cl(2) and C(6)D(6). PMID:22087634

Schulz, Felix; Sumerin, Victor; Heikkinen, Sami; Pedersen, Björn; Wang, Cong; Atsumi, Michiko; Leskelä, Markku; Repo, Timo; Pyykkö, Pekka; Petry, Winfried; Rieger, Bernhard

2011-12-21

225

Hydrogen-deuterium exchange mass spectrometry as an emerging analytical tool for stabilization and formulation development of therapeutic monoclonal antibodies.  

PubMed

The dynamic nature of the structure of monoclonal antibodies (mAbs) can be probed at a resolution of 5-20 residues using hydrogen-deuterium exchange mass spectrometry (H/D-MS). Recent studies using H/D-MS have shown that distinct regions of IgG1 mAbs experience significant changes in backbone dynamics in response to specific physicochemical alterations, varying solution conditions, or exposure to different environmental stresses. Tracking such changes in local dynamics may therefore serve as a key analytical tool, not only to monitor stability changes, but also to design improved, and more stable formulations of therapeutic mAbs in pharmaceutical dosage forms. This review article describes the H/D-MS method as applied to the analysis of formulations containing mAbs and summarizes recent studies monitoring changes in mAb local dynamics in response to chemical modifications, physical degradation, and presence of stabilizing and destabilizing excipients. Furthermore, the nature of the local dynamics of a highly conserved peptide segment in the CH 2 domain of IgG1 mAbs is reviewed, and the results are correlated with decreased pharmaceutical stability, supporting the identification of a common aggregation hotspot sequence in the Fc region of human IgG1 mAbs. In addition, unresolved challenges (and opportunities) in applying H/D-MS technology for stabilization and formulation development of mAbs are discussed. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:327-345, 2015. PMID:25354868

Majumdar, Ranajoy; Middaugh, C Russell; Weis, David D; Volkin, David B

2015-02-01

226

Comparative Analysis of Oxy-Hemoglobin and Aquomet-Hemoglobin by Hydrogen/Deuterium Exchange Mass Spectrometry  

NASA Astrophysics Data System (ADS)

The function of hemoglobin (Hb) as oxygen transporter is mediated by reversible O2 binding to Fe(2+) heme in each of the ? and ? subunits. X-ray crystallography revealed different subunit arrangements in oxy-Hb and deoxy-Hb. The deoxy state is stabilized by additional contacts, causing a rigidification that results in strong protection against hydrogen/deuterium exchange (HDX). Aquomet-Hb is a dysfunctional degradation product with four water-bound Fe(3+) centers. Heme release from aquomet-Hb is relatively facile, triggering oxidative damage of membrane lipids. Aquomet-Hb crystallizes in virtually the same conformation as oxy-Hb. Hence, it is commonly implied that the solution-phase properties of aquomet-Hb should resemble those of the oxy state. This work compares the structural dynamics of oxy-Hb and aquomet-Hb by HDX mass spectrometry (MS). It is found that the aquomet state exhibits a solution-phase structure that is significantly more dynamic, as manifested by elevated HDX levels. These enhanced dynamics affect the aquomet ? and ? subunits in a different fashion. The latter undergoes global destabilization, whereas the former shows elevated HDX levels only in the heme binding region. It is proposed that these enhanced dynamics play a role in facilitating heme release from aquomet-Hb. Our findings should be of particular interest to the MS community because oxy-Hb and aquomet-Hb serve as widely used test analytes for probing the relationship between biomolecular structure in solution and in the gas phase. We are not aware of any prior comparative HDX/MS experiments on oxy-Hb and aquomet-Hb.

Sowole, Modupeola A.; Konermann, Lars

2013-07-01

227

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

PubMed

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

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

2015-04-01

228

Pt NANOCLUSTERS ON CARBON NANOMATERIALS FOR HYDROGEN FUEL CELLS  

Microsoft Academic Search

The detailed study of carbon nanomaterials constitution with allowance for of reduction conversions Pt (II, IV) allows to\\u000a realize directional looking up of methods of preparation of platinum catalysts for redox reactions in hydrogen fuel cells.

N. S. KUYUNKO; S. D. KUSHCH; V. E. MURADYAN; A. A. VOLODIN; V. I. TORBOV; B. P. TARASOV

229

Physisorption of molecular hydrogen on carbon nanotube with vacant defects  

NASA Astrophysics Data System (ADS)

Physisorption of molecular hydrogen on single-walled carbon nanotubes (SWCNTs) is important for its engineering applications and hydrogen energy storage. Using molecular dynamics simulation, we study the physisorption of molecular hydrogen on a SWCNT with a vacant defect, focusing on the effect of the vacant defect size and external parameters such as temperature and pressure. We find that hydrogen can be physisorbed inside a SWCNT through a vacant defect when the defect size is above a threshold. By controlling the size of the defects, we are able to extract hydrogen molecules from a gas mixture and store them inside the SWCNT. We also find that external parameters, such as low temperature and high pressure, enhance the physisorption of hydrogen molecules inside the SWCNT. In addition, the storage efficiency can be improved by introducing more defects, i.e., reducing the number of carbon atoms on the SWCNT.

Sun, Gang; Tangpanitanon, Jirawat; Shen, Huaze; Wen, Bo; Xue, Jianming; Wang, Enge; Xu, Limei

2014-05-01

230

Physisorption of molecular hydrogen on carbon nanotube with vacant defects  

SciTech Connect

Physisorption of molecular hydrogen on single-walled carbon nanotubes (SWCNTs) is important for its engineering applications and hydrogen energy storage. Using molecular dynamics simulation, we study the physisorption of molecular hydrogen on a SWCNT with a vacant defect, focusing on the effect of the vacant defect size and external parameters such as temperature and pressure. We find that hydrogen can be physisorbed inside a SWCNT through a vacant defect when the defect size is above a threshold. By controlling the size of the defects, we are able to extract hydrogen molecules from a gas mixture and store them inside the SWCNT. We also find that external parameters, such as low temperature and high pressure, enhance the physisorption of hydrogen molecules inside the SWCNT. In addition, the storage efficiency can be improved by introducing more defects, i.e., reducing the number of carbon atoms on the SWCNT.

Sun, Gang; Shen, Huaze; Wang, Enge; Xu, Limei, E-mail: limei.xu@pku.edu.cn [International Center for Quantum Materials and School of Physics, Peking University, Beijing 100871 (China); Collaborative Innovation Center of Quantum Matter, Beijing (China); Tangpanitanon, Jirawat [University of Cambridge, Cambridge, Cambridgeshire CB2 1TP (United Kingdom); Wen, Bo [International Center for Quantum Materials and School of Physics, Peking University, Beijing 100871 (China); Beijing Computational Science Research Center, Heqing Street, Haidian District, Beijing 100084 (China); Xue, Jianming [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China); Center for Applied Physics and Technology, Peking University, Beijing 100871 (China)

2014-05-28

231

Experimental investigations of electron capture from atomic hydrogen and deuterium by alpha particles. Annual progress report, 15 September 1991--14 September 1992  

SciTech Connect

We report progress made during the period 15 September 1991--14 September 1992 on the project ``Experimental Investigations of Electron Capture from Atomic Hydrogen and Deuterium by Alpha Particles``. In the past year we have developed reliable, narrow energy spread, high-current sources of He{sup ++} based on direct-current magentron and electron-cyclotron resonance discharges. These sources have been proven on our test bench accelerator which has been upgraded to also allow us to test atomic hydrogen effusive targets. We have thus made substantial progress toward our goal of studying single electron capture from atomic hydrogen by doubly-ionized helium. A research plan for the upcoming year is also presented.

Gay, T.J.; Park, J.T.

1992-11-01

232

Hydrogen uptake by carbon nanofibers catalyzed by palladium  

Microsoft Academic Search

Carbon nanofibers of herringbone conformation were obtained by chemical vapor deposition on Pd\\/La2O3 catalyst, from ethylene—hydrogen mixture. After the removal of La2O3, samples with various Pd\\/C ratios were obtained by oxidation in air. The hydrogen sorption capacities measured gravimetrically at 10MPa in pure hydrogen, for six different batches of samples, show a good correlation with the Pd\\/C ratio reveling a

Dan Lupu; Alexandru Radu Biri?; Ioan Mi?an; Adrian Jianu; Gerd Holzhüter; Eberhard Burkel

2004-01-01

233

Hydrogen adsorption on carbon-doped boron nitride nanotube.  

PubMed

The adsorption of atomic and molecular hydrogen on carbon-doped boron nitride nanotubes is investigated within the ab initio density functional theory. The binding energy of adsorbed hydrogen on carbon-doped boron nitride nanotube is substantially increased when compared with hydrogen on nondoped nanotube. These results are in agreement with experimental results for boron nitride nanotubes (BNNT) where dangling bonds are present. The atomic hydrogen makes a chemical covalent bond with carbon substitution, while a physisorption occurs for the molecular hydrogen. For the H(2) molecule adsorbed on the top of a carbon atom in a boron site (BNNT + C(B)-H(2)), a donor defect level is present, while for the H(2) molecule adsorbed on the top of a carbon atom in a nitrogen site (BNNT + C(N)-H(2)), an acceptor defect level is present. The binding energies of H(2) molecules absorbed on carbon-doped boron nitride nanotubes are in the optimal range to work as a hydrogen storage medium. PMID:17048943

Baierle, Rogério J; Piquini, Paulo; Schmidt, Tomé M; Fazzio, Adalberto

2006-10-26

234

Evidence for a bound water molecule next to the retinal Schiff base in bacteriorhodopsin and rhodopsin: a resonance Raman study of the Schiff base hydrogen/deuterium exchange.  

PubMed Central

The retinal chromophores of both rhodopsin and bacteriorhodopsin are bound to their apoproteins via a protonated Schiff base. We have employed continuous-flow resonance Raman experiments on both pigments to determine that the exchange of a deuteron on the Schiff base with a proton is very fast, with half-times of 6.9 +/- 0.9 and 1.3 +/- 0.3 ms for rhodopsin and bacteriorhodopsin, respectively. When these results are analyzed using standard hydrogen-deuteron exchange mechanisms, i.e., acid-, base-, or water-catalyzed schemes, it is found that none of these can explain the experimental results. Because the exchange rates are found to be independent of pH, the deuterium-hydrogen exchange can not be hydroxyl (or acid-)-catalyzed. Moreover, the deuterium-hydrogen exchange of the retinal Schiff base cannot be catalyzed by water acting as a base because in that case the estimated exchange rate is predicted to be orders of magnitude slower than that observed. The relatively slow calculated exchange rates are essentially due to the high pKa values of the Schiff base in both rhodopsin (pKa > 17) and bacteriorhodopsin (pKa approximately 13.5). We have also measured the deuterium-hydrogen exchange of a protonated Schiff base model compound in aqueous solution. Its exchange characteristics, in contrast to the Schiff bases of the pigments, is pH-dependent and consistent with the standard base-catalyzed schemes. Remarkably, the water-catalyzed exchange, which has a half-time of 16 +/- 2 ms and which dominates at pH 3.0 and below, is slower than the exchange rate of the Schiff base in rhodopsin and bacteriorhodopsin. Thus, there are two anomalous results, the inconsistency of the observed hydrogen exchange rates of retinal Schiff base in the two pigments with those predicted from the standard exchange schemes and the enhancement of the rate of hydrogen exchange in the two proteins over the model Schiff base in aqueous solution. We suggest that these results are explained by the presence of a structural water molecule (or molecules) at the retinal binding sites of the two pigments, quite close, probably-hydrogen bonded, to the Schiff base proton. In this case, the rate of exchange can be faster than that found for the model compound due to an "effective water concentration" near the Schiff base that is increased from that found in aqueous solution. PMID:8038384

Deng, H.; Huang, L.; Callender, R.; Ebrey, T.

1994-01-01

235

Carbon-deuterium bonds as non-perturbative infrared probes of protein dynamics, electrostatics, heterogeneity, and folding.  

PubMed

Vibrational spectroscopy is uniquely able to characterize protein dynamics and microenvironmental heterogeneity because it possesses an inherently high temporal resolution and employs probes of ultimately high structural resolution-the bonds themselves. The use of carbon-deuterium (C-D) bonds as vibrational labels circumvents the spectral congestion that otherwise precludes the use of vibrational spectroscopy to proteins and makes the observation of single vibrations within a protein possible while being wholly non-perturbative. Thus, C-D probes can be used to site-specifically characterize conformational heterogeneity and thermodynamic stability. C-D probes are also uniquely useful in characterizing the electrostatic microenvironment experienced by a specific residue side chain or backbone due to its effect on the C-D absorption frequency. In this chapter we describe the experimental procedures required to use C-D bonds and FT IR spectroscopy to characterize protein dynamics, structural and electrostatic heterogeneity, ligand binding, and folding. PMID:24061918

Zimmermann, Jörg; Romesberg, Floyd E

2014-01-01

236

Using Hydrogen/Deuterium Exchange Mass Spectrometry to Define the Specific Interactions of the Phospholipase A2 Superfamily with Lipid Substrates, Inhibitors, and Membranes*  

PubMed Central

The phospholipase A2 (PLA2) superfamily consists of 16 groups and many subgroups and constitutes a diverse set of enzymes that have a common catalytic activity due to convergent evolution. However, different PLA2 types have unique three-dimensional structures and catalytic residues as well as specific tissue localization and distinct biological functions. Understanding how the different PLA2 enzymes associate with phospholipid membranes, specific phospholipid substrate molecules, and inhibitors on a molecular basis has advanced in recent years due to the introduction of hydrogen/deuterium exchange mass spectrometry. Its theory, practical considerations, and application to understanding PLA2/membrane interactions are addressed. PMID:23209293

Cao, Jian; Burke, John E.; Dennis, Edward A.

2013-01-01

237

Hydrogenated amorphous silicon carbon alloys for solar cells  

Microsoft Academic Search

Hydrogenated amorphous silicon carbon films were grown by PECVD from silane\\/methane gas mixtures by fixing the methane ratio in the gas phase and by changing the rf power and pressure. The effects of the discharge parameters on the optical, electrical and structural properties were investigated. These effects were attributed to the variation of carbon content in the film. The analyses

Giuseppina Ambrosone; Ubaldo Coscia; Stefano Lettieri; Pasqualino Maddalena; Carlo Privato; Sergio Ferrero

2002-01-01

238

Single Membrane Reactor Configuration for Separation of Hydrogen, Carbon Dioxide and Hydrogen Sulfide  

Microsoft Academic Search

The objective of the project was to develop a novel complementary membrane reactor process that can consolidate two or more downstream unit operations of a coal gasification system into a single module for production of a pure stream of hydrogen and a pure stream of carbon dioxide. The overall goals were to achieve higher hydrogen production efficiencies, lower capital costs

Micheal Roberts; Robert Zabransky; Shain Doong; Jerry Lin

2008-01-01

239

Hydrogen-deficient atmospheres for cool carbon stars  

NASA Technical Reports Server (NTRS)

Motivated by recent work which hints at a possible deficiency of hydrogen in non-Mira N-type carbon stars and to further explore the parameter space of chemical composition, computations have been made of a series of hydrogen-deficient models for carbon stars. For these models Teff = 3000 K, and log g = 0.0. Solar abundances are used for all elements except for carbon (which is enhanced to give C/O = 1.05), hydrogen, and helium. As the fractional abundance of hydrogen is decreased, being replaced by helium, the temperature-optical depth relation is affected only slightly, but the temperature-pressure relation is changed. The most striking change in the emergent flux is the decrease of the H(-) peak at 1.65 micron compared with the blackbody peak at 1.00 micron.

Johnson, H. R.; Bower, C. D.; Lemke, D. A.; Luttermoser, D. G.; Petrakis, J. P.; Reinhart, M. D.; Welch, K. A.; Alexander, D. R.; Goebel, J. H.

1985-01-01

240

Determining interstellar hydrogen and deuterium column densities by means of the Lyman channel of the SPECTRUM UV Rowland spectrograph: a pre-launch feasibility study  

NASA Astrophysics Data System (ADS)

Our current knowledge of production and destruction of light elements in astrophysical processes suggests that deuterium is produced during Big Bang nucleosynthesis and destroyed when cycled through stars. Primordial deuterium abundance can be determined by measuring the D/H ratio in a variety of astrophysical environments with different degrees of chemical evolution: the D/H ratio of unprocessed material directly gives the primordial value, while the ratio in processed material is expected to be lower and consistent with the predictions of galactic chemical evolution models. Here we focus our attention on deuterium abundance determinations of chemically processed material such as the interstellar gas in our Galaxy. Up to now, most of the determinations of deuterium abundance have been performed in the solar system or in local interstellar clouds. However, the overall accuracy of the measurements in local clouds is still insufficient to probe evolutionary trends. New D/H measurements in clouds at different locations in our Galaxy would be necessary to establish this issue, while interstellar measurements in nearby galaxies would give further constraints on the deuterium evolution in different galactic environments. With this goal in mind we have evaluated the capability of the Lyman channel of the SPECTRUM UV Rowland spectrography in determining deuterium column density in distant interstellar clouds. Three packages have been used to obtain realistic predicted spectra and to derive `observed' column densities: (1) the MIDAS package `CLOUD', to generate theoretical interstellar absorption profiles; (2) the `Synth' package developed in the IRAF environment by two of the authors to simulate spectroscopic observations of point sources obtainable with an astronomical spectrograph, (3) the FITLYMAN package inside the Lyman context of MIDAS to derive `observed' column densities from predicted spectra. The minimum exposure times, t(subscript min), required to obtain a approximately 0.1 dex accuracy in the `observed' column densities, were derived by varying the input interstellar hydrogen column density. As a result, we show that the Lyman channel of the SPECTRUM UV Rowland spectrograph is up to the task of deriving accurate H and D column densities of low and medium column density interstellar clouds while it fails for N(HI) >= 10(superscript 21) atoms cm(superscript -2).

Franchini, Mariagrazia; Morossi, Carlo; Vladilo, G.

1996-10-01

241

Hydrogen evolution reaction of low carbon steel electrode in hydrochloric acid as a source for hydrogen production  

Microsoft Academic Search

The hydrogen evolution reaction (HER) (cathodic reaction) of low carbon steel electrode immersed in hydrochloric acid was investigated as a source for hydrogen production. Corrosion rate, hydrogen evolution rate, and current density increase with the increase of HCl concentration. Theoretically and practically, every 1g of iron produces about 0.036g of hydrogen. Therefore, the hydrogen production efficiency over the immersion period

A. A. El-Meligi; N. Ismail

2009-01-01

242

In situ deuterium observation in deuterium-implanted tungsten  

NASA Astrophysics Data System (ADS)

In order to evaluate the tritium inventory in plasma-facing tungsten components of a fusion reactor, deuterium depth profiles in tungsten were observed in situ using nuclear reaction analysis (NRA) under continuous implantation of 3 keV D ions. Measurements were conducted at temperatures of 384, 473, 573 and 673 K. Recombination coefficients and rate constants for the surface recombination process were estimated from the observed deuterium concentration. It is indicated that the measured surface recombination rate constant is applied in a case wherein tungsten is exposed to hydrogen particles of various energies from a fusion plasma. The measured recombination coefficient was identical to that found by a different technique in a previous work. Deuterium in trap sites was found to contribute to deuterium retention in the samples as well as to deuterium in solution sites. The deuterium retention was low in the 384 K sample, in which trap sites had not appeared. Deuterium retention was very low in the 673 K sample, where most deuterium atoms were detrapped and desorbed. At an intermediate temperature of 473 K, the retention showed a maximum value due to a large occupancy of deuterium over many trap sites. The dependence of the retention on deuterium fluence was explained assuming that trap sites were produced by implantation.

Furuta, Yoshinori; Takagi, Ikuji; Kawamura, Shotaro; Yamamichi, Kazuyoshi; Akiyoshi, Masafumi; Sasaki, Takayuki; Kobayashi, Taishi

2013-11-01

243

TENSILE TESTING OF CARBON STEEL IN HIGH PRESSURE HYDROGEN  

SciTech Connect

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.

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

2007-05-02

244

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

PubMed

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

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

2006-01-01

245

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

NASA Astrophysics Data System (ADS)

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.

Winterberg, F.

2013-08-01

246

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

PubMed

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

Cho, Kyu Taek; Mench, Matthew M

2012-03-28

247

MECHANICAL TESTING OF CARBON STEEL IN HIGH PRESSURE HYDROGEN  

SciTech Connect

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.

Duncan, A

2006-05-11

248

Assessing Carbon and Hydrogen Isotopic Fractionation of Diesel Fuel n-alkanes During Progressive Evaporation.  

PubMed

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

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

2015-01-01

249

Hydrogen Confinement in Carbon Nanopores: Extreme Densification at Ambient Temperature  

SciTech Connect

In-situ small angle neutron scattering (SANS) studies of hydrogen confined in small pores of polyfurfuryl alcohol-derived activated carbon (PFAC) at room-temperature provided for the first time its phase behavior in equilibrium with external H2 at pressures up to 200 bar. The data was used to evaluate the density of the adsorbed fluid, which appears to be a function of both pore size and pressure, and approaches the liquid hydrogen density in narrow nanopores at 200 bar. The surface-molecule interactions responsible for densification of hydrogen within the pores create internal pressures which exceed by a factor of up to ~ 60 the external gas pressures, confirming the benefits of adsorptive over compressive storage. These results can be utilized to guide the development of new carbon adsorbents tailored for maximum hydrogen storage capacities at near ambient temperatures.

Gallego, Nidia C [ORNL; He, Lilin [ORNL; Saha, Dipendu [ORNL; Contescu, Cristian I [ORNL; Melnichenko, Yuri B [ORNL

2011-01-01

250

Deuterium-free water ( 1H2O) in complex life-support systems of long-term space missions  

NASA Astrophysics Data System (ADS)

Heavy water containing deuterium displays toxic property. It is stated that any quantity of a heavy isotope of hydrogen—deuterium—is undesirable to animals and plants. It was earlier shown by us that physical-chemical life support systems on board the "MIR" station fractionate (change) isotopes of hydrogen, oxygen and carbon. Therefore, the problem of regenerative systems in habitable space objects should include removal, from water, of a heavy stable isotope of hydrogen—deuterium. In this article we consider one method of obtaining deuterium-free water—decomposition of distillate water in an electrolyser to hydrogen and oxygen with subsequent synthesis in a catalytic or high-temperature reactor. The influence of deuterium-free water on the growth and development of Arabidopsis thaliana and Japanese quail is investigated. It is shown that with the help of the electrolysis method it is possible to fabricate water containing 80% less deuterium in comparison with SMOW. Experimentally, it is proved on a culture of Arabidopsis thaliana and Japanese quail that water with reduced contents of deuterium (80%) displays positive biological activity.

Sinyak, Y.; Grigoriev, A.; Gaydadimov, V.; Gurieva, T.; Levinskih, M.; Pokrovskii, B.

251

Deuterium-free water (1H2O) in complex life-support systems of long-term space missions.  

PubMed

Heavy water containing deuterium displays toxic property. It is stated that any quantity of a heavy isotope of hydrogen--deuterium--is undesirable to animals and plants. It was earlier shown by us that physical-chemical life support systems on board the "MIR" station fractionate (change) isotopes of hydrogen, oxygen and carbon. Therefore, the problem of regenerative systems in habitable space objects should include removal, from water, of a heavy stable isotope of hydrogen--deuterium. In this article we consider one method of obtaining deuterium-free water--decomposition of distillate water in an electrolyser to hydrogen and oxygen with subsequent synthesis in a catalytic or high-temperature reactor. The influence of deuterium-free water on the growth and development of Arabidopsis thaliana and Japanese quail is investigated. It is shown that with the help of the electrolysis method it is possible to fabricate water containing 80% less deuterium in comparison with SMOW. Experimentally, it is proved on a culture of Arabidopsis thaliana and Japanese quail that water with reduced contents of deuterium (80%) displays positive biological activity. PMID:12575722

Sinyak, Y; Grigoriev, A; Gaydadimov, V; Gurieva, T; Levinskih, M; Pokrovskii, B

2003-04-01

252

Isotopic inferences of ancient biochemistries - Carbon, sulfur, hydrogen, and nitrogen  

NASA Technical Reports Server (NTRS)

In processes of biological incorporation and subsequent biochemical processing sizable isotope effects occur as a result of both thermodynamic and kinetic fractionations which take place during metabolic and biosynthetic reactions. In this chapter a review is provided of earlier work and recent studies on isotope fractionations in the biogeochemical cycles of carbon, sulfur, hydrogen, and nitrogen. Attention is given to the biochemistry of carbon isotope fractionation, carbon isotope fractionation in extant plants and microorganisms, isotope fractionation in the terrestrial carbon cycle, the effects of diagenesis and metamorphism on the isotopic composition of sedimentary carbon, the isotopic composition of sedimentary carbon through time, implications of the sedimentary carbon isotope record, the biochemistry of sulfur isotope fractionation, pathways of the biogeochemical cycle of nitrogen, and the D/H ratio in naturally occurring materials.

Schidlowski, M.; Hayes, J. M.; Kaplan, I. R.

1983-01-01

253

Theoretical analysis of hydrogen spillover mechanism on carbon nanotubes  

NASA Astrophysics Data System (ADS)

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.

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

2015-02-01

254

Theoretical analysis of hydrogen spillover mechanism on carbon nanotubes  

PubMed Central

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

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

2015-01-01

255

Theoretical analysis of hydrogen spillover mechanism on carbon nanotubes.  

PubMed

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

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

2015-01-01

256

Material processing with hydrogen and carbon monoxide on Mars  

NASA Technical Reports Server (NTRS)

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.

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

1991-01-01

257

Stereoselective heterocycle synthesis through oxidative carbon-hydrogen bond activation.  

PubMed

Heterocycles are ubiquitous structures in both drugs and natural products, and efficient methods for their construction are being pursued constantly. Carbon-hydrogen bond activation offers numerous advantages for the synthesis of heterocycles with respect to minimizing the length of synthetic routes and reducing waste. As interest in chiral medicinal leads increases, stereoselective methods for heterocycle synthesis must be developed. The use of carbon-hydrogen bond activation reactions for stereoselective heterocycle synthesis has produced a range of creative transformations that provide a wide array of structural motifs, selected examples of which are described in this review. PMID:21061234

Liu, Lei; Floreancig, Paul E

2010-01-01

258

NMR studies of nucleic acids. Deuterium isotope effects on sup 13 C chemical shifts in hydrogen-bonded complexes of pyrimidines and purines  

SciTech Connect

{sup 13}C NMR spectra were recorded for chloroform solutions of 2',3'-O-isopropylidene-5'-O-acetyladenosine (1), 2',3',5'-O-tribenzoyluridine (2), 2',3'-O-isopropylidene-5'-O-acetyluridine (2a), 2',3'-O-isopropylidene-5'-O-(tert-butyldimethylsilyl)guanosine (3), and 2',3'-O-isopropylidene-5'-O-(tert-butyldimethylsilyl)cytidine (4) in which the imino hydrogens were partially exchanged with deuterium. Upfield two-bond deuterium isotope effects (DIE) on {sup 13}C chemical shifts were detected under conditions of slow exchange as multiple peaks for the appropriate resonances and ranged in magnitude from 40 ppB for the amino interaction with C2 in guanosine to 217 ppB for the imino interaction with C4 in the uridine self-association dimer. {sup 13}C chemical shifts and DIEs for 2 were measured at 12 different concentrations from 219 to 231 K. The data were used in an iterative procedure to estimate chemical shifts at C2 and C4 for monomeric and dimeric forms of 2, equilibrium constants and enthalpies for self-association, and the distribution of isomeric self-association dimers. Enthalpies for formation of hydrogen bonds to C2 and C4 in 2 were similar, {Delta}H = {minus}1.8 kcal/mol. DIEs at C2 and C4 increased upon formation of a hydrogen bond to the carbonyl oxygens. The maximal increase for each center was estimated to be 90 ppB. Small increases were also observed in DIEs when nucleosides 1-4 were mixed with their complementary bases. 38 refs., 3 figs., 7 tabs.

Gmeiner, W.H.; Poulter, C.D.

1988-11-09

259

Palladium-doped Nanoporous Carbon Fibers for Hydrogen Storage  

SciTech Connect

Pd-free and Pd-containing activated carbon fibers (Pd-ACF) were synthesized from isotropic pitch as a carbon precursor. The source of Pd was a palladium salt that was premixed with pitch before carbonization. Hydrogen adsorption was measured at near-ambient temperatures (5 to 80 oC) and moderate pressures (up to 20 bar). It was found that adsorption on Pd-ACF is always higher than that on corresponding ACF, and in excess of what it would be expected based solely on formation of Pd hydride. This fact can be explained based on the mechanism of hydrogen spillover. It was also found that temperature and pressure have opposite effects on physisorption and spillover. It was hypothesized that a narrow temperature range exists, where the kinetic advantage of H2 spillover in Pd-ACF overlaps synergistically with the thermodynamic advantage of physisorption, thus contributing to enhanced uptakes compared with the Pd-free carbons.

Gallego, Nidia C [ORNL] [ORNL; Contescu, Cristian I [ORNL] [ORNL; Bhat, Vinay V [ORNL] [ORNL; van Benthem, Klaus [ORNL] [ORNL; Tekinalp, Halil [Clemson University] [Clemson University; Edie, Dan [Clemson University] [Clemson University

2008-01-01

260

Polar Aprotic Modifiers for Chromatographic Separation and Back-Exchange Reduction for Protein Hydrogen/Deuterium Exchange Monitored by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry  

NASA Astrophysics Data System (ADS)

Hydrogen/deuterium exchange monitored by mass spectrometry is an important non-perturbing tool to study protein structure and protein-protein interactions. However, water in the reversed-phase liquid chromatography mobile phase leads to back-exchange of D for H during chromatographic separation of proteolytic peptides following H/D exchange, resulting in incorrect identification of fast-exchanging hydrogens as unexchanged hydrogens. Previously, fast high-performance liquid chromatography (HPLC) and supercritical fluid chromatography have been shown to decrease back-exchange. Here, we show that replacement of up to 40% of the water in the LC mobile phase by the modifiers, dimethylformamide (DMF) and N-methylpyrrolidone (NMP) (i.e., polar organic modifiers that lack rapid exchanging hydrogens), significantly reduces back-exchange. On-line LC micro-ESI FT-ICR MS resolves overlapped proteolytic peptide isotopic distributions, allowing for quantitative determination of the extent of back-exchange. The DMF modified solvent composition also improves chromatographic separation while reducing back-exchange relative to conventional solvent.

Valeja, Santosh G.; Emmett, Mark R.; Marshall, Alan G.

2012-04-01

261

Polar Aprotic Modifiers for Chromatographic Separation and Back-Exchange Reduction for Protein Hydrogen/Deuterium Exchange Monitored by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry  

PubMed Central

Hydrogen/deuterium exchange monitored by mass spectrometry is an important non-perturbing tool to study protein structure and protein–protein interactions. However, water in the reversed-phase liquid chromatography mobile phase leads to back-exchange of D for H during chromatographic separation of proteolytic peptides following H/D exchange, resulting in incorrect identification of fast-exchanging hydrogens as unexchanged hydrogens. Previously, fast high-performance liquid chromatography (HPLC) and supercritical fluid chromatography have been shown to decrease back-exchange. Here, we show that replacement of up to 40% of the water in the LC mobile phase by the modifiers, dimethylformamide (DMF) and N-methylpyrrolidone (NMP) (i.e., polar organic modifiers that lack rapid exchanging hydrogens), significantly reduces back-exchange. On-line LC micro-ESI FT-ICR MS resolves overlapped proteolytic peptide isotopic distributions, allowing for quantitative determination of the extent of back-exchange. The DMF modified solvent composition also improves chromatographic separation while reducing back-exchange relative to conventional solvent. PMID:22298288

Valeja, Santosh G.; Emmett, Mark R.; Marshall, Alan G.

2013-01-01

262

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

Code of Federal Regulations, 2014 CFR

...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...

2014-07-01

263

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

Code of Federal Regulations, 2012 CFR

...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...

2012-07-01

264

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

Code of Federal Regulations, 2013 CFR

...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...

2013-07-01

265

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

Code of Federal Regulations, 2011 CFR

...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...

2011-07-01

266

Hydrogen retention and carbon deposition in plasma facing components and the shadowed area of JT-60U  

NASA Astrophysics Data System (ADS)

In JT-60U, erosion/deposition analyses of the plasma facing wall have shown that local carbon transport in the inboard direction was appreciable in addition to long-range transport. The total deposition and erosion rates in the divertor region were ~1 × 1021 C atoms s-1 and ~-6 × 1020 C atoms s-1, respectively. About 40% of the deposition in the divertor region likely originates from the main chamber wall. At the plasma facing surfaces of the divertor region, the highest hydrogen concentration in the (H + D)/C ratio and the retention amount were found to be ~0.13 and ~1 × 1023 atoms m-2, respectively. In the plasma-shadowed area underneath the divertor region with a vacuum vessel baking temperature of 420 K, redeposited layers of ~2 µm thickness were found with a high hydrogen concentration of ~0.75 in (H + D)/C, which was nearly the same level as that observed in JET. Large deuterium retention was also observed at the main chamber wall covered with boron layers. Their H + D retention and (H + D)/C were ~1 × 1023 atoms m-2 and ~0.16, respectively, for the vacuum vessel temperature of 570 K. Such a high deuterium retention is most likely caused by D retained in the boron layers. Nevertheless, the integration of this retention over the whole main chamber wall results in significant inventory and needs further investigation.

Masaki, K.; Tanabe, T.; Hirohata, Y.; Oya, Y.; Shibahara, T.; Hayashi, T.; Sugiyama, K.; Arai, T.; Okuno, K.; Miya, N.

2007-11-01

267

Hydrogen Bonds Involved in Binding the Qi-site Semiquinone in the bc1 Complex, Identified through Deuterium Exchange  

E-print Network

Hydrogen Bonds Involved in Binding the Qi-site Semiquinone in the bc1 Complex, Identified through them. The strength of interactions indicates that the protons are involved in hydrogen bonds with SQ. The hyperfine cou- plings differ from values typical for in-plane hydrogen bonds previously observed in model

Crofts, Antony R.

268

Deuterium Gas Analysis by Residual Gas Analyzer  

NASA Astrophysics Data System (ADS)

Hydrogen gas is generated by electrolysis method in a compact hydrogen generator. A simple procedure reduces handling and storage of hydrogen cylinders for laboratory applications. In such a system, we are producing deuterium gas from heavy water by electrolysis method. After production of the deuterium gas, we have checked the purity level of the outgoing deuterium from the electrolyser. The test was carried out in a high vacuum system in which one residual gas analyser (RGA) was mounted. The deuterium gas was inserted by one manual gas leak valve in to the vacuum system. In this study, the effect of the emission current of the RGA on the detection of the deuterium was performed. In this paper, we will discuss the detail analysis of the deuterium gas and the effect of the emission current on the partial pressure measurement.

Das, B. K.; Shukla, R.; Das, R.; Shyam, A.; Rao, A. D. P.

2012-11-01

269

TRANSITION METAL ACTIVATION AND FUNCTIONALIZATION OF CARBON-HYDROGEN BONDS  

E-print Network

TRANSITION METAL ACTIVATION AND FUNCTIONALIZATION OF CARBON-HYDROGEN BONDS William D. Jones, New York 14627 FOR #12;DOE Report, 1998-2001 2 William D. Jones Overview of Research Accomplishments will extend this work to #12;DOE Report, 1998-2001 3 William D. Jones other early metal compounds during

Jones, William D.

270

Carbon phases versus hydrogen phases: neutral gas in nearby galaxies  

NASA Astrophysics Data System (ADS)

Due to its lower-than-hydrogen first ionization energy, atomic carbon is ionized throughout the diffuse ISM, tracing both regions of ioinized and neutral hydrogen gas. On the other hand, carbon monoxide (CO) exists and emits exclusively where hydrogen is in molecular form. Neutral atomic carbon is predicted to exist in between these phases, but recent evidence in our Galaxy and from simulations show it may be closely tied to the molecular gas than previously thought. Here, we investigate the gas in various carbon stages (evidenced through emission in [CII], [CI] and CO) compared to hydrogen stages (through ?CO-corrected CO for H2 and HI emission). The observations are based upon the Beyond the Peak sample of 22 galaxies with data from the Herschel Space Observatory SPIRE FTS instrument, as well as relying on ground-based CO and HI observations. Based on these comparisons, [CI] does trace CO well and thus may provide a good way to trace molecular gas in external galaxies as well as in molecular clouds in the Milky Way.

Crocker, Alison Faye; Pellegrini, Eric; Smith, John-David T.; Beyond the Peak Team

2015-01-01

271

Properties Of Plasma-Deposited Amorphous Hydrogenated Carbon  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

272

Electrocatalytic production of hydrogen on reticulated vitreous carbon  

Microsoft Academic Search

Reticulated vitreous carbon (RVC) was used as a porous cathode for the production of hydrogen gas from flowing alkaline solution. Polarization curves were measured to evaluate the overall performance of the RVC electrode. By an aid of a mathematical model, the kinetic parameters for HER at different conditions were estimated by fitting the experimental data with the model predictions. Black

M. S El-Deab; Mahmoud M Saleh

2003-01-01

273

Hydrogenation of Single-Wall Carbon Nanotubes Using Polyamine Reagents: Combined Experimental and  

E-print Network

oxidation of SWNTs using some combination of sulfuric acid, nitric acid, and occasionally hydrogen peroxide9Hydrogenation of Single-Wall Carbon Nanotubes Using Polyamine Reagents: Combined Experimental hydrogenation of single-wall carbon nanotubes using high boiling polyamines as hydrogenation reagents. Our

274

Effect of B-Z transition and nucleic acid structure on the conformational dynamics of bound ethidium dimer measured by hydrogen deuterium exchange kinetics.  

PubMed Central

Ethidium dimer is shown to bind by intercalation, almost equally well, to the B and Z form of poly[(dG-m5dC)].poly[(dG-m5dC)], whereas the ethidium monomer shows a strong preference for the B form. The hydrogen-deuterium (H-D) exchange kinetics of the ethidium dimer bound to the B and Z form of poly [(dG-m5dC)].poly[(dG-m5dC)] could then be compared. The kinetics of the H-D exchange were strikingly slower when the dye was bound to Z DNA as compared to B DNA. The exchange kinetics were also modified when ethidium dimer was bound to tRNA and to a triple stranded structure. It is proposed that a dynamic fluctuation at the level of the nucleic acid could modulate the dynamic fluctuation at the level of the bound ligand. PMID:4011442

Markovits, J; Ramstein, J; Roques, B P; Le Pecq, J B

1985-01-01

275

PHYSIOLOGICAL ECOLOGY -ORIGINAL PAPER Carbon and hydrogen isotope fractionation under continuous  

E-print Network

PHYSIOLOGICAL ECOLOGY - ORIGINAL PAPER Carbon and hydrogen isotope fractionation under continuous intensity continuous light, e.g., in the High Arctic summer, on plant carbon and hydrogen isotope on both carbon and hydrogen isotope com- positions of three deciduous conifers whose fossil counterparts

276

Variation of Hydrogen, Carbon, Nitrogen, and Oxygen Stable Isotope Ratios in an American Diet  

E-print Network

Variation of Hydrogen, Carbon, Nitrogen, and Oxygen Stable Isotope Ratios in an American Diet: Fast isotopes of hydrogen, carbon, nitrogen, and oxygen provide insights into a heterotrophic organism's diet component within the diet. KEYWORDS: Stable isotope; hydrogen; carbon; nitrogen; oxygen; American diet; fast

Ehleringer, Jim

277

Crucial role of perfringolysin O D1 domain in orchestrating structural transitions leading to membrane-perforating pores: a hydrogen-deuterium exchange study.  

PubMed

Perfringolysin O (PFO) is a toxic protein that binds to cholesterol-containing membranes, oligomerizes, and forms a ?-barrel transmembrane pore, leading to cell lysis. Previous studies have uncovered the sequence of events in this multistage structural transition to a considerable detail, but the underlying molecular mechanisms are not yet fully understood. By measuring hydrogen-deuterium exchange patterns of peptide bond amide protons monitored by mass spectrometry (MS), we have mapped structural changes in PFO and its variant bearing a point mutation during incorporation to the lipid environment. We have defined all regions that undergo structural changes caused by the interaction with the lipid environment both in wild-type PFO, thus providing new experimental constraints for molecular modeling of the pore formation process, and in a point mutant, W165T, for which the pore formation process is known to be inefficient. We have demonstrated that point mutation W165T causes destabilization of protein solution structure, strongest for domain D1, which interrupts the pathway of structural transitions in other domains necessary for proper oligomerization in the membrane. In PFO, the strongest changes accompanying binding to the membrane focus in D1; the C-terminal part of D4; and strands ?1, ?4, and ?5 of D3. These changes were much weaker for PFO(W165T) lipo where substantial stabilization was observed only in D4 domain. In this study, the application of hydrogen-deuterium exchange analysis monitored by MS provided new insight into conformational changes of PFO associated with the membrane binding, oligomerization, and lytic pore formation. PMID:25164812

Kacprzyk-Stokowiec, Aleksandra; Kulma, Magdalena; Traczyk, Gabriela; Kwiatkowska, Katarzyna; Sobota, Andrzej; Dadlez, Micha?

2014-10-10

278

Shock compression of precompressed deuterium  

SciTech Connect

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.

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

2011-07-31

279

Carbon-palladium films as gas sensors (hydrogen, ammonia, methane)  

NASA Astrophysics Data System (ADS)

In this paper we present the results of the resistances changes of carbon-palladium films under the influences of gas like hydrogen, ammonia and methane. Our research has shown that carbon-palladium films (C-Pd films) according to the form and the structure in which they appear, they can respond to a variety of gases. The C-Pd film obtained by Physical Vapor Deposition (PVD) method is sensitive to hydrogen and do not respond to the ammonia. Thermal modification of the C-Pd film in Chemical Vapor Deposition (CVD) process affects the morphology of the film, increases its resistance and it causes that this film begins to react to the ammonia. This change causes that this film stops responding on hydrogen. Film sensitive to methane was obtained by changing the technology conditions of the PVD process. The reaction of C-Pd film on the hydrogen and the ammonia is increase resistance, while film sensitive to methane reacts by decrease of initial resistance value. In both cases, the changes are reversible after cleaning by air atmosphere. Different varieties of C-Pd films can be used to build selective sensors for hydrogen, ammonia and methane.

Rymarczyk, Joanna; Kami?ska, Anna; Krawczyk, S?awomir

2014-11-01

280

Adsorption of carbon monoxide and hydrogen on graphite.  

NASA Technical Reports Server (NTRS)

Adsorption of carbon monoxide and hydrogen was investigated on three graphites: a high-density pyrolytic graphite, a small-grain extruded graphite, and a processed pyrolytic graphite tape. The sticking probability of CO was found to decrease rapidly as the average surface coverage approached 0.01 monolayer. Lower sticking probabilities were observed on the highly oriented pyrolytic graphite which indicated that adsorption occurs principally on the edge atoms. There is negligible adsorption of molecular hydrogen on graphite that has been heated to 2400 K in vacuo.

Beitel, G. A.

1972-01-01

281

Atomistic Simulation of Carbon Nanotube Ropes and Hydrogen Absorption  

NASA Astrophysics Data System (ADS)

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.

Li, Ju; Yip, Sidney; Fujiwara, Joshua

2001-06-01

282

Mechanism of enhanced hydrogen adsorption on palladium-doped nanoporous carbon fibers  

SciTech Connect

Recent work at Oak Ridge National Laboratory was directed towards adsorptive storage of hydrogen in nanoporous carbon fibers in which palladium was incorporated prior to spinning and carbonization/activation of the fibers. Palladium doped carbon fibers exhibited enhanced hydrogen uptake compared to the corresponding palladium-free nanoporous carbon fibers (at room temperature and 2 MPa pressure). However, the mechanism responsible for the enhanced hydrogen uptake is not fully understood. New findings are presented in this paper in support of a mechanism that encompasses both hydrogen spillover on palladium metal sites and hydrogen physisorption on nanostructured carbon sites.

Contescu, Cristian I [ORNL; Gallego, Nidia C [ORNL; Wu, Xianxian [ORNL; Tekinalp, Halil [Clemson University; Edie, Dan [Clemson University; Thies, Mark C [ORNL; Baker, Frederick S [ORNL

2007-01-01

283

Theoretical investigation of planar square carbon allotrope and its hydrogenation  

NASA Astrophysics Data System (ADS)

Using density functional theory we investigate a novel carbon allotrope ‘SqC’: a square planar material that can be more than tetracoordinated. Carbon atoms in this 2D square Bravais lattice form an unusual five-center four-electron bond with neighboring four carbon atoms (tetracoordination). Such an electron-deficient bonding leaves an empty orbital which enables penta- or hexa-coordinated carbon atom. Indeed, our simulations demonstrate such penta- and hexa-coordinated configurations upon partial and complete hydrogenation, respectively. Surprisingly, in all the forms SqC shows the metallic character. SqC has the binding energy of 6.7 eV and it also satisfies the Born stability criteria. Yet our phonon calculations show that it may only be considered as quasi-stable.

Pujari, Bhalchandra S.; Tokarev, Andrey; Saraf, Deepashri A.

2012-05-01

284

Estimating groundwater mixing and origin in an overexploited aquifer in Guanajuato, Mexico, using stable isotopes (strontium-87, carbon-13, deuterium and oxygen-18).  

PubMed

Stable Isotopes (strontium-87, deuterium and oxygen-18, carbon-13) have been used to reveal different sources of groundwater and mixing processes in the aquifer of the Silao-Romita Valley in the state of Guanajuato, Mexico. Calcite dissolution appeared to be the main process of strontium release leading to relatively equal (87)Sr/(86)Sr ratios of 0.7042-0.7062 throughout the study area which could be confirmed by samples of carbonate rocks having similar Sr ratios (0.7041-0.7073). delta(13)C values (-11.91- -6.87 per thousand VPDB) of groundwaters confirmed the solution of carbonates but indicated furthermore influences of soil-CO(2). Deuterium and (18)O contents showed a relatively narrow range of-80.1- -70.0 per thousand VSMOW and -10.2- -8.8 per thousand, VSMOW, respectively but are affected by evaporation and mixing processes. The use of delta(13)C together with (87)Sr/(86)Sr revealed three possible sources: (i) carbonate-controlled waters showing generally higher Sr-concentrations, (ii) fissure waters with low-strontium contents and (iii) infiltrating water which is characterized by low delta(13)C and (87)Sr/(86)Sr ratios. The third component is affected by evaporation processes taking place before and during infiltration which might be increased by extraction and reinfiltration (irrigation return flow). PMID:18041622

Horst, Axel; Mahlknecht, Jürgen; Merkel, Broder J

2007-12-01

285

Hydrogen sensing properties of palladium-decorated carbon nanotube circuits  

NASA Astrophysics Data System (ADS)

Sensitive hydrogen gas sensors can be fabricated from carbon nanotube circuits decorated with palladium metal, and we have investigated the responsible physical mechanisms using isolated, single-walled carbon nanotubes (SWCNTs). Hydrogen sensitivity arises from two active mechanisms, neither of which is the mere adsorption of Pd onto pristine SWCNTs. The first mechanism relies on the chemical sensitivity of Schottky barriers present when semiconducting SWCNTs are contacted by metals. Pd decoration of the barrier region, or the use of pure Pd as the contact metal, produces a modest H2 sensitivity, if any. A more sensitive mechanism involves Pd-decorated defect sites, which in both metallic and semiconducting SWNTs results in reversible conductance swings of 100%. This presentation will review the temporal dynamics and pressure dependence of both mechanisms.

Khalap, Vaikunth; Sheps, Tatyana; Kane, Alexander; Collins, Philip

2008-03-01

286

Renewable hydrogen and carbon nanotubes from biodiesel waste glycerol  

PubMed Central

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

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

2013-01-01

287

Hydrogenated 5-carbon compound and method of making  

DOEpatents

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. 8 figs.

Elliott, D.C.; Frye, J.G.

1999-03-16

288

Hydrogenated 5-carbon compound and method of making  

DOEpatents

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.

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

1999-01-01

289

Automated data reduction for hydrogen/deuterium exchange experiments, enabled by high-resolution Fourier transform ion cyclotron resonance mass spectrometry.  

PubMed

Mass analysis of proteolytic fragment peptides following hydrogen/deuterium exchange offers a general measure of solvent accessibility/hydrogen bonding (and thus conformation) of solution-phase proteins and their complexes. The primary problem in such mass analyses is reliable and rapid assignment of mass spectral peaks to the correct charge state and degree of deuteration of each fragment peptide, in the presence of substantial overlap between isotopic distributions of target peptides, autolysis products, and other interferant species. Here, we show that at sufficiently high mass resolving power (m/Delta m(50%) > or = 100,000), it becomes possible to resolve enough of those overlaps so that automated data reduction becomes possible, based on the actual elemental composition of each peptide without the need to deconvolve isotopic distributions. We demonstrate automated, rapid, reliable assignment of peptide masses from H/D exchange experiments, based on electrospray ionization FT-ICR mass spectra from H/D exchange of solution-phase myoglobin. Combined with previously demonstrated automated data acquisition for such experiments, the present data reduction algorithm enhances automation (and thus expands generality and applicability) for high-resolution mass spectrometry-based analysis of H/D exchange of solution-phase proteins. PMID:20116280

Kazazic, Sasa; Zhang, Hui-Min; Schaub, Tanner M; Emmett, Mark R; Hendrickson, Christopher L; Blakney, Gregory T; Marshall, Alan G

2010-04-01

290

Automated Data Reduction for Hydrogen/Deuterium Exchange Experiments, Enabled by High-Resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry  

PubMed Central

Mass analysis of proteolytic fragment peptides following hydrogen/deuterium exchange offers a general measure of solvent accessibility/hydrogen bonding (and thus conformation) of solution-phase proteins and their complexes. The primary problem in such mass analyses is reliable and rapid assignment of mass spectral peaks to the correct charge state and degree of deuteration of each fragment peptide, in the presence of substantial overlap between isotopic distributions of target peptides, autolysis products, and other interferant species. Here, we show that at sufficiently high mass resolving power (m/?m50% ? 100,000), it becomes possible to resolve enough of those overlaps so that automated data reduction becomes possible, based on the actual elemental composition of each peptide without the need to deconvolve isotopic distributions. We demonstrate automated, rapid, reliable assignment of peptide masses from H/D exchange experiments, based on electrospray ionization FT-ICR mass spectra from H/D exchange of solution-phase myoglobin. Combined with previously demonstrated automated data acquisition for such experiments, the present data reduction algorithm enhances automation (and thus expands generality and applicability) for high-resolution mass spectrometry- based analysis of H/D exchange of solution-phase proteins. PMID:20116280

Kazazic, Sasa; Zhang, Hui-Min; Schaub, Tanner M.; Emmett, Mark R.; Hendrickson, Christopher L.; Blakney, Gregory T.; Marshall, Alan G.

2010-01-01

291

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

E-print Network

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...

Roueff, E; Hickson, K M

2015-01-01

292

Optimization of Nano-Carbon Materials for Hydrogen Sorption  

SciTech Connect

Research undertaken has added to the understanding of several critical areas, by providing both negative answers (and therefore eliminating expensive further studies of unfeasible paths) and positive feasible options for storage. Theoretical evaluation of the early hypothesis of storage on pure carbon single wall nanotubes (SWNT) has been scrutinized with the use of comprehensive computational methods (and experimental tests by the Center partners), and demonstrated that the fundamentally weak binding energy of hydrogen is not sufficiently enhanced by the SWNT curvature or even defects, which renders carbon nanotubes not practical media. More promising direction taken was towards 3-dimensional architectures of high porosity where concurrent attraction of H2 molecule to surrounding walls of nano-scale cavities can double or even triple the binding energy and therefore make hydrogen storage feasible even at ambient or somewhat lower temperatures. An efficient computational tool has been developed for the rapid capacity assessment combining (i) carbon-foam structure generation, (ii) accurate empirical force fields, with quantum corrections for the lightweight H2, and (iii) grand canonical Monte Carlo simulation. This made it possible to suggest optimal designs for carbon nanofoams, obtainable via welding techniques from SWNT or by growth on template-zeolites. As a precursor for 3D-foams, we have investigated experimentally the synthesis of VANTA (Vertically Aligned NanoTube Arrays). This can be used for producing nano-foams. On the other hand, fluorination of VANTA did not show promising increase of hydrogen sorption in several tests and may require further investigation and improvements. Another significant result of this project was in developing a fundamental understanding of the elements of hydrogen spillover mechanisms. The benefit of developed models is the ability to foresee possible directions for further improvement of the spillover mechanism.

Yakobson, Boris I [Rice University

2013-08-02

293

Carbon and hydrogen isotope fractionation resulting from anaerobic methane oxidation  

Microsoft Academic Search

Methane oxidation in the anoxic sediments of Skan Bay, Alaska resulted in fractionation of carbon and hydrogen isotopes in methane. Isotope fractionation factors were estimated by fitting methane concentration, delta C¹³-CHâ and delta-D-CHâ data with depth distributions predicted by an open system, steady state model. Assuming that molecular diffusion coefficients for C¹²-CHâ, C¹³-CHâ, and C¹²-CHâD are identical, the predicted fractionation

M. J. Alperin; W. S. Reeburgh; M. J. Whiticar

1988-01-01

294

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

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

295

Towards efficient solar hydrogen production by intercalated carbon nitride photocatalyst.  

PubMed

The development of efficient photocatalytic material for converting solar energy to hydrogen energy as viable alternatives to fossil-fuel technologies is expected to revolutionize energy shortage and environment issues. However, to date, the low quantum yield for solar hydrogen production over photocatalysts has hindered advances in the practical applications of photocatalysis. Here, we show that a carbon nitride intercalation compound (CNIC) synthesized by a simple molten salt route is an efficient polymer photocatalyst with a high quantum yield. We found that coordinating the alkali metals into the C-N plane of carbon nitride will induce the un-uniform spatial charge distribution. The electrons are confined in the intercalated region while the holes are in the far intercalated region, which promoted efficient separation of photogenerated carriers. The donor-type alkali metal ions coordinating into the nitrogen pots of carbon nitrides increase the free carrier concentration and lead to the formation of novel nonradiative paths. This should favor improved transport of the photogenerated electron and hole and decrease the electron-hole recombination rate. As a result, the CNIC exhibits a quantum yield as high as 21.2% under 420 nm light irradiation for solar hydrogen production. Such high quantum yield opens up new opportunities for using cheap semiconducting polymers as energy transducers. PMID:24061109

Gao, Honglin; Yan, Shicheng; Wang, Jiajia; Huang, Yu An; Wang, Peng; Li, Zhaosheng; Zou, Zhigang

2013-11-01

296

Hydrogen and carbon monoxide production by hydrocarbon steam reforming and pressure swing adsorption purification  

SciTech Connect

This patent describes a method for producing hydrogen and carbon monoxide from a feed mixture comprising hydrogen, carbon monoxide, carbon dioxide, and methane. It comprises passing the feed mixture through a first pressure swing adsorption system containing an adsorption bed comprising an adsorbent having a greater affinity for carbon dioxide, methane, and carbon monoxide than for hydrogen to separate hydrogen as a pure non-adsorbed product and carbon dioxide, methane, and carbon monoxide as an adsorbed fraction; desorbing carbon monoxide from the pressure swing adsorption system to form a carbon monoxide-rich fraction; desorbing carbon dioxide and methane from the pressure swing absorption system to form a carbon dioxide-rich fraction; passing the carbon monoxide-rich fraction to a second pressure swing adsorption system containing an adsorption bed comprising an adsorbent having a greater affinity for carbon monoxide than for hydrogen, carbon dioxide, and methane to separate carbon monoxide as an absorbed fraction and hydrogen, carbon dioxide, and methane as a non-adsorbed fraction; and desorbing carbon monoxide from the pressure swing adsorption system to form a pure carbon monoxide product.

Krishnamurthy, R.

1992-03-17

297

Sulfur and Hydrogen Isotope Anomalies in Meteorite Sulfonic Acids  

NASA Technical Reports Server (NTRS)

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.

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

1997-01-01

298

Sulfur and Hydrogen Isotope Anomalies in Meteorite Sulfonic Acids  

NASA Astrophysics Data System (ADS)

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.

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

1997-08-01

299

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

NASA Astrophysics Data System (ADS)

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 molecules containing carbon. Aims: Using a time-dependent gas-phase chemical model, we check the underlying hypothesis that the 13C/12C ratio of nitriles and isonitriles is equal to the elemental value. Methods: We built a chemical network that contains 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 two different physical conditions that correspond to a moderately dense cloud in an early evolutionary stage and a dense, depleted prestellar core tend to show that ammonia and its singly deuterated form are somewhat enriched in 15N, which agrees with observations. The 14N/15N ratio in N2H+ is found to be close to the elemental value, in contrast to previous models that obtain a significant enrichment, because we found that the fractionation reaction between 15N and N2H+ has a barrier in the entrance channel. The high values of the N2H+/15NNH+ and N2H+/N15NH+ ratios derived in L1544 cannot be reproduced in our model. Finally, we find that nitriles and isonitriles are in fact significantly depleted in 13C, thereby challenging previous interpretations of observed C15N, HC15N, and H15NC abundances from 13C containing isotopologues. Appendices are available in electronic form at http://www.aanda.org

Roueff, E.; Loison, J. C.; Hickson, K. M.

2015-04-01

300

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

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.

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

1989-01-01

301

Hydrogen storage reactions on titanium decorated carbon nanocones theoretical study  

NASA Astrophysics Data System (ADS)

Hydrogen storage reactions on Ti decorated carbon nanocones (CNC) are investigated by using the state of the art density functional theory calculations. The single Ti atom prefers to bind at the bridge site between two hexagonal rings, and can bind up to 6 hydrogen molecules with average adsorption energies of -1.73, -0.74, -0.57, -0.45, -0.42, and -0.35 eV per hydrogen molecule. No evidence for metal clustering in the ideal circumstances, and the hydrogen storage capacity is expected to be as large as 14.34 wt%. Two types of interactions are recognized. While the interaction of 2H2 with Ti-CNC is irreversible at 532 K, the interaction of 3H2 with Ti-CNC is reversible at 392 K. Further characterizations of the former two reactions are considered in terms of projected densities of states, simulated infrared and proton magnetic resonance spectra, electrophilicity, and statistical thermodynamic stability. The free energy of the highest hydrogen storage capacity reaction between 6H2 and Ti-CNC meets the ultimate targets of department of energy at (233.15 K) and (11.843 atm) with surface coverage (0.941) and (direct/inverse) rate constants ratio (1.35).

Shalabi, A. S.; Taha, H. O.; Soliman, K. A.; Abeld Aal, S.

2014-12-01

302

Laser induced crystallization of hydrogenated amorphous silicon-carbon alloys  

NASA Astrophysics Data System (ADS)

Laser induced crystallization of hydrogenated amorphous silicon carbon alloy (a-Si1-xCx:H) films has been investigated by means of synchrotron x-ray diffraction. The a-Si1-xCx:H films were deposited on (100) silicon wafers by very high frequency plasma enhanced chemical vapor deposition at 100MHz in hydrogen diluted silane-methane gas mixtures. The substrate was kept at 250°C or 350°C and the stoichiometry was changed from x =0.20 to 0.63. The structural characterization of the as-grown films has been carried out by Rutherford backscattering (hydrogen concentration) and infrared spectroscopy (film ordering). The films were irradiated by a KrF excimer laser (248nm ) with varying energy density and number of pulses. After irradiation, the formation of SiC crystallites has been revealed by synchrotron x-ray diffraction. Besides SiC nanocrystals, the formation of crystalline Si and graphite is observed for under- (x <0.50) and over-stoichiometric (x>0.50) samples, respectively. The essential role played by hydrogen concentration and hydrogen bonding configuration in determining the melting threshold and the consequent SiC grain formation is highlighted.

Summonte, C.; Rizzoli, R.; Servidori, M.; Milita, S.; Nicoletti, S.; Bianconi, M.; Desalvo, A.; Iencinella, D.

2004-10-01

303

Laser induced crystallization of hydrogenated amorphous silicon-carbon alloys  

SciTech Connect

Laser induced crystallization of hydrogenated amorphous silicon carbon alloy (a-Si{sub 1-x}C{sub x}:H) films has been investigated by means of synchrotron x-ray diffraction. The a-Si{sub 1-x}C{sub x}:H films were deposited on (100) silicon wafers by very high frequency plasma enhanced chemical vapor deposition at 100 MHz in hydrogen diluted silane-methane gas mixtures. The substrate was kept at 250 deg. C or 350 deg. C and the stoichiometry was changed from x=0.20 to 0.63. The structural characterization of the as-grown films has been carried out by Rutherford backscattering (hydrogen concentration) and infrared spectroscopy (film ordering). The films were irradiated by a KrF excimer laser (248 nm) with varying energy density and number of pulses. After irradiation, the formation of SiC crystallites has been revealed by synchrotron x-ray diffraction. Besides SiC nanocrystals, the formation of crystalline Si and graphite is observed for under- (x<0.50) and over-stoichiometric (x>0.50) samples, respectively. The essential role played by hydrogen concentration and hydrogen bonding configuration in determining the melting threshold and the consequent SiC grain formation is highlighted.

Summonte, C.; Rizzoli, R.; Servidori, M.; Milita, S.; Nicoletti, S.; Bianconi, M.; Desalvo, A.; Iencinella, D. [CNR-IMM Section of Bologna, Via Gobetti 101, I-40129 Bologna (Italy); DICASM, University of Bologna, Viale Risorgimento 2, I-40136 Bologna (Italy)

2004-10-01

304

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

E-print Network

, and hydrogen, reflecting the widespread occurrence of oxygen-containing organic material in the atmosphere.7Using 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

305

Molecular Dynamics Simulation of Hydrogen Storage with Single Walled Carbon Nanotubes Shigeo MARUYAMA1,2  

E-print Network

Molecular Dynamics Simulation of Hydrogen Storage with Single Walled Carbon Nanotubes * Shigeo-8656 The hydrogen storage mechanism of SWNTs was studied through molecular dynamics simulations. Assuming the simple : Molecular Dynamics Method, Hydrogen Storage, Single Walled Carbon Nanotubes, Lennard-Jones, Adsorption

Maruyama, Shigeo

306

Mechanics of hydrogen storage in carbon nanotubes Y.L. Chen a  

E-print Network

Mechanics of hydrogen storage in carbon nanotubes Y.L. Chen a , B. Liu a,Ã?, J. Wu a , Y. Huang b 17 July 2008 Keywords: Hydrogen storage Carbon nanotube Continuum model Analytical solution Atomistic simulations a b s t r a c t A continuum mechanics model is established for hydrogen storage in single

Jiang, Hanqing

307

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

NASA Astrophysics Data System (ADS)

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.

Sauter, P. A.; Balden, M.

2013-09-01

308

Noncatalytic hydrogenation of decene-1 with hydrogen accumulated in a hybrid carbon nanostructure in nanosized membrane reactors  

NASA Astrophysics Data System (ADS)

Studies on the creation of nanosized membrane reactors (NMRs) of a new generation with accumulated hydrogen and a regulated volume of reaction zone were continued at the next stage. Hydrogenation was performed in the pores of ceramic membranes with hydrogen preliminarily adsorbed in mono- and multilayered orientated carbon nanotubes with graphene walls (OCNTGs)—a new hybrid carbon nanostructure formed on the inner pore surface. Quantitative determination of hydrogen adsorption in OCNTGs was performed using TRUMEM ultrafiltration membranes with D av = 50 and 90 nm and showed that hydrogen adsorption was up to ˜1.5% of the mass of OCNTG. The instrumentation and procedure for noncatalytic hydrogenation of decene-1 at 250-350°C using hydrogen accumulated and stored in OCNTG were developed. The conversion of decene-1 into decane was ˜0.2-1.8% at hydrogenation temperatures of 250 and 350°C, respectively. The rate constants and activation energy of hydrogenation were determined. The latter was found to be 94.5 kJ/mol, which is much smaller than the values typical for noncatalytic hydrogenations and very close to the values characteristic for catalytic reactions. The quantitative distribution of the reacting compounds in each pore regarded as a nanosized membrane reactor was determined. The activity of hydrogen adsorbed in a 2D carbon nanostructure was evaluated. Possible mechanisms of noncatalytic hydrogenation were discussed.

Soldatov, A. P.

2014-08-01

309

Graphene growth using a solid carbon feedstock and hydrogen.  

PubMed

Graphene has been grown on Cu at elevated temperatures with different carbon sources (gaseous hydrocarbons and solids such as polymers); however the detailed chemistry occurring at the Cu surface is not yet known. Here, we explored the possibility of obtaining graphene using amorphous-carbon thin films, without and with hydrogen gas added. Graphene is formed only in the presence of H(2)(g), which strongly suggests that gaseous hydrocarbons and/or their intermediates are what yield graphene on Cu through the reaction of H(2)(g) and the amorphous carbon. The large area, uniform monolayer graphene obtained had electron and hole mobilities of 2520 and 2050 cm(2) V(-1) s(-1), respectively. PMID:21879747

Ji, Hengxing; Hao, Yufeng; Ren, Yujie; Charlton, Matthew; Lee, Wi Hyoung; Wu, Qingzhi; Li, Huifeng; Zhu, Yanwu; Wu, Yaping; Piner, Richard; Ruoff, Rodney S

2011-09-27

310

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

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

311

Finite element model for charge and discharge cycle of activated carbon hydrogen storage  

Microsoft Academic Search

One of the main challenges to introduce hydrogen on the energy market is to improve on-board hydrogen storage and develop more efficient distribution technologies to increase the amount of stored gas while lowering the storage pressure. The physisorption of hydrogen on activated carbons (AC) is being investigated as a possible route for hydrogen storage. The objective of this work is

Jinsheng Xiao; Jijuan Wang; Daniel Cossement; Pierre Bénard; Richard Chahine

312

Hydrogen storage and delivery: the carbon dioxide - formic acid couple.  

PubMed

Carbon dioxide and the carbonates, the available natural C1 sources, can be easily hydrogenated into formic acid and formates in water; the rate of this reduction strongly depends on the pH of the solution. This reaction is catalysed by ruthenium(II) pre-catalyst complexes with a large variety of water-soluble phosphine ligands; high conversions and turnover numbers have been realised. Although ruthenium(II) is predominant in these reactions, the iron(II) - tris[(2-diphenylphosphino)-ethyl]phosphine (PP3) complex is also active, showing a new perspective to use abundant and inexpensive iron-based compounds in the CO2 reduction. In the catalytic hydrogenation cycles the in situ formed metal hydride complexes play a key role, their structures with several other intermediates have been proven by multinuclear NMR spectroscopy. In the other hand safe and convenient hydrogen storage and supply is the fundamental question for the further development of the hydrogen economy; and carbon dioxide has been recognised to be a viable H2 vector. Formic acid--containing 4.4 weight % of H2, that is 53 g hydrogen per litre--is suitable for H2 storage; we have shown that in aqueous solutions it can be selectively decomposed into CO-free (CO < 10 ppm) CO2 and H2. The reaction takes place under mild experimental conditions and it is able to generate high pressure H2 (up to 600 bar). The cleavage of HCOOH is catalysed by several hydrophilic Ru(II) phosphine complexes (meta-trisulfonated triphenylphosphine, mTPPTS, being the most efficient one), either in homogeneous systems or as immobilised catalysts. We have also shown that the iron(II)--hydrido tris[(2-diphenylphosphino)ethyl]phosphine complex catalyses with an exceptionally high rate and efficiency (turnover frequency, TOF = 9425 h(-1)mol(-1); turnover number, TON = 92400) the formic acid cleavage, in environmentally friendly propylene carbonate solution, opening the way to use cheap, non-noble metal based catalysts for this reaction, too. PMID:22026175

Laurenczy, Gábor

2011-01-01

313

Influence of concurrent substances on removal of hydrogen sulfide by activated carbon  

Microsoft Academic Search

The influence of concurrent substances on the removal of hydrogen sulfide by activated carbon was determined. The hydrogen sulfide removal ratio of an activated carbon column was measured after breakthrough of each of the substances used. At 30°C, the adsorption capacity of carbon for toluene, ethanol, carbon disulfide, butanol and isobutanol was 0.19, 0.036, 0.043, 0.13 and 0.12g\\/g-carbon, respectively. The

Junji Masuda; Joji Fukuyama; Satoshi Fujii

1999-01-01

314

Atomic hydrogen interactions with amorphous carbon thin films  

NASA Astrophysics Data System (ADS)

The atomic-scale interactions of H atoms with hydrogenated amorphous carbon (a-C:H) films were identified using molecular dynamics (MD) simulations and experiments based on surface characterization tools. Realistic a-C:H films developed using MD simulations were impinged with H atoms with a kinetic energy corresponding to a temperature of 700 K. The specific chemical reactions of the H atoms with the a-C:H surface were identified through a detailed analysis of the MD trajectories. The MD simulations showed that hydrogenation occurs primarily at the sp2 sites and converts them to sp3-hybridized C atoms. Depending on the hybridization of the next-nearest neighbor, a dangling bond may or may not be created. The hydrogenation reaction is highly exothermic, >2.5 eV, and proceeds with a negligible activation energy barrier via a mechanism similar to Eley-Rideal. In certain cases hydrogenation may also cleave a C-C bond. The reaction events observed through MD simulations are consistent with the surface characterization of D-exposed a-C:H films using Raman spectroscopy, spectroscopic ellipsometry, and in situ attenuated total reflection Fourier-transform infrared spectroscopy.

Jariwala, Bhavin N.; Ciobanu, Cristian V.; Agarwal, Sumit

2009-10-01

315

Gas phase hydrogen permeation in alpha titanium and carbon steels  

NASA Technical Reports Server (NTRS)

Commercially pure titanium and heats of Armco ingot iron and steels containing from 0.008-1.23 w/oC were annealed or normalized and machined into hollow cylinders. Coefficients of diffusion for alpha-Ti and alpha-Fe were determined by the lag-time technique. Steady state permeation experiments yield first power pressure dependence for alpha-Ti and Sievert's law square root dependence for Armco iron and carbon steels. As in the case of diffusion, permeation data confirm that alpha-titanium is subject to at least partial phase boundary reaction control while the steels are purely diffusion controlled. The permeation rate in steels also decreases as the carbon content increases. As a consequence of Sievert's law, the computed hydrogen solubility decreases as the carbon content increases. This decreases in explained in terms of hydrogen trapping at carbide interfaces. Oxidizing and nitriding the surfaces of alpha-titanium membranes result in a decrease in the permeation rate for such treatment on the gas inlet surfaces but resulted in a slight increase in the rate for such treatment on the gas outlet surfaces. This is explained in terms of a discontinuous TiH2 layer.

Johnson, D. L.; Shah, K. K.; Reeves, B. H.; Gadgeel, V. L.

1980-01-01

316

Vector and tensor analyzing powers for [polarized deuterons on hydrogen] and [polarized deuterons on deuterium with neutrons] at E[subscript d]=45.5 MeV  

E-print Network

of the deuterium atom in a magnetic field, B, where B 117 gauss. . . . . . . . . . . . . . . . . . . 9 Schematic of experimental setup. 14 10 12 13 14 15 16 17 Simplified schematic diagram of the electronics used for data acquisition. I(T, P) for 1H... for acceleration. In operation, molecular deuterium gas is fed into a glass tube at the top of the ion source where it is dissociated into atomic deuterium by an r. f. discharge (f 20 MHz) ~ The atomic deuterium beam passes through a sextupole magnet where...

Woodward, Warren Fred

1983-01-01

317

Performance of CVD and CVR coated carbon-carbon in high temperature hydrogen  

NASA Astrophysics Data System (ADS)

As a part of the component development process for the particle bed reactor (PBR), it is necessary to develop coatings which will be time and temperature stable at extremely high temperatures in flowing hydrogen. These coatings must protect the underlying carbon structure from attack by the hydrogen coolant. Degradation which causes small changes in the reactor component, e.g. hole diameter in the hot frit, can have a profound effect on operation. The ability of a component to withstand repeated temperature cycles is also a coating development issue. Coatings which crack or spall under these conditions would be unacceptable. While refractory carbides appear to be the coating material of choice for carbon substrates being used in PBR components, the method of applying these coatings can have a large effect on their performance. Two deposition processes for these refractory carbides, chemical vapor deposition (CVD) and chemical vapor reaction (CVR), have been evaluated. Screening tests for these coatings consisted of testing of coated 2-D and 3-D weave carbon-carbon in flowing hot hydrogen at one atmosphere. Carbon loss from these samples was measured as a function of time. Exposure temperatures up to 3,000 K were used, and samples were exposed in a cyclical fashion cooling to room temperature between exposures. The results of these measurements are presented along with an evaluation of the relative merits of CVR and CVD coatings for this application.

Adams, J. W.; Barletta, R. E.; Svandrlik, J.; Vanier, P. E.

318

Iron-catalyzed hydrogenation of bicarbonates and carbon dioxide to formates.  

PubMed

The catalytic hydrogenation of carbon dioxide and bicarbonate to formate has been explored extensively. The vast majority of the known active catalyst systems are based on precious metals. Herein, we describe an effective, phosphine-free, air- and moisture-tolerant catalyst system based on Knölker's iron complex for the hydrogenation of bicarbonate and carbon dioxide to formate. The catalyst system can hydrogenate bicarbonate at remarkably low hydrogen pressures (1-5?bar). PMID:25603778

Zhu, Fengxiang; Zhu-Ge, Ling; Yang, Guangfu; Zhou, Shaolin

2015-02-01

319

Hydrogen Storage in Single-Walled Carbon Nanotubes at Room Temperature  

Microsoft Academic Search

Masses of single-walled carbon nanotubes (SWNTs) with a large mean diameter of about 1.85 nanometers, synthesized by a semicontinuous hydrogen arc discharge method, were employed for hydrogen adsorption experiments in their as-prepared and pretreated states. A hydrogen storage capacity of 4.2 weight percent, or a hydrogen to carbon atom ratio of 0.52, was achieved reproducibly at room temperature under a

C. Liu; Y. Y. Fan; M. Liu; H. T. Cong; H. M. Cheng; M. S. Dresselhaus

1999-01-01

320

Dissecting the binding mode of low affinity phage display peptide ligands to protein targets by hydrogen/deuterium exchange coupled to mass spectrometry.  

PubMed

Phage display (PD) is frequently used to discover peptides capable of binding to biological protein targets. The structural characterization of peptide-protein complexes is often challenging due to their low binding affinities and high structural flexibility. Here, we investigate the use of hydrogen/deuterium exchange mass spectrometry (HDX-MS) to characterize interactions of low affinity peptides with their cognate protein targets. The HDX-MS workflow was optimized to accurately detect low-affinity peptide-protein interactions by use of ion mobility, electron transfer dissociation, nonbinding control peptides, and statistical analysis of replicate data. We show that HDX-MS can identify regions in the two epigenetic regulator proteins KDM4C and KDM1A that are perturbed through weak interactions with PD-identified peptides. Two peptides cause reduced HDX on opposite sides of the active site of KDM4C, indicating distinct binding modes. In contrast, the perturbation site of another PD-selected peptide inhibiting the function of KDM1A maps to a GST-tag. Our results demonstrate that HDX-MS can validate and map weak peptide-protein interactions and pave the way for understanding and optimizing the binding of peptide scaffolds identified through PD and similar ligand discovery approaches. PMID:25325890

Leurs, Ulrike; Lohse, Brian; Ming, Shonoi; Cole, Philip A; Clausen, Rasmus P; Kristensen, Jesper L; Rand, Kasper D

2014-12-01

321

External reflection FTIR of peptide monolayer films in situ at the air/water interface: experimental design, spectra-structure correlations, and effects of hydrogen-deuterium exchange.  

PubMed Central

A Fourier transform infrared spectrometer has been interfaced with a surface balance and a new external reflection infrared sampling accessory, which permits the acquisition of spectra from protein monolayers in situ at the air/water interface. The accessory, a sample shuttle that permits the collection of spectra in alternating fashion from sample and background troughs, reduces interference from water vapor rotation-vibration bands in the amide I and amide II regions of protein spectra (1520-1690 cm-1) by nearly an order of magnitude. Residual interference from water vapor absorbance ranges from 50 to 200 microabsorbance units. The performance of the device is demonstrated through spectra of synthetic peptides designed to adopt alpha-helical, antiparallel beta-sheet, mixed beta-sheet/beta-turn, and unordered conformations at the air/water interface. The extent of exchange on the surface can be monitored from the relative intensities of the amide II and amide I modes. Hydrogen-deuterium exchange may lower the amide I frequency by as much as 11-12 cm-1 for helical secondary structures. This shifts the vibrational mode into a region normally associated with unordered structures and leads to uncertainties in the application of algorithms commonly used for determination of secondary structure from amide I contours of proteins in D2O solution. PMID:7919013

Flach, C R; Brauner, J W; Taylor, J W; Baldwin, R C; Mendelsohn, R

1994-01-01

322

Sites involved in intra- and interdomain allostery associated with the activation of factor viia pinpointed by hydrogen-deuterium exchange and electron transfer dissociation mass spectrometry.  

PubMed

Factor VIIa (FVIIa) is a trypsin-like protease that plays an important role in initiating blood coagulation. Very limited structural information is available for the free, inactive form of FVIIa that circulates in the blood prior to vascular injury and the molecular details of its activity enhancement remain elusive. Here we have applied hydrogen/deuterium exchange mass spectrometry coupled to electron transfer dissociation to pinpoint individual residues in the heavy chain of FVIIa whose conformation and/or local interaction pattern changes when the enzyme transitions to the active form, as induced either by its cofactor tissue factor or a covalent active site inhibitor. Identified regulatory residues are situated at key sites across one continuous surface of the protease domain spanning the TF-binding helix across the activation pocket to the calcium binding site and are embedded in elements of secondary structure and at the base of flexible loops. Thus these residues are optimally positioned to mediate crosstalk between functional sites in FVIIa, particularly the cofactor binding site and the active site. Our results unambiguously show that the conformational allosteric activation signal extends to the EGF1 domain in the light chain of FVIIa, underscoring a remarkable intra- and interdomain allosteric regulation of this trypsin-like protease. PMID:25344622

Song, Hongjian; Olsen, Ole H; Persson, Egon; Rand, Kasper D

2014-12-19

323

Hydrogen-deuterium isotope shift: From the 1S-2S-transition frequency to the proton-deuteron charge-radius difference  

SciTech Connect

We analyze and review the theory of the hydrogen-deuterium isotope shift for the 1S-2S transition, which is one of the most accurately measured isotope shifts in any atomic system, in view of a recently improved experiment. A tabulation of all physical effects that contribute to the isotope shift is given. These include the Dirac binding energy, quantum electrodynamic effects, including recoil corrections, and the nuclear-size effect, including the pertaining relativistic and radiative corrections. From a comparison of the theoretical result {Delta}f{sub th}=670 999 566.90(66)(60) kHz (exclusive of the nonrelativistic nuclear-finite-size correction) and the experimental result {Delta}f{sub expt}=670 994 334 605(15) Hz, we infer the deuteron-proton charge-radius difference {sub d}-{sub p}=3.820 07(65) fm{sup 2} and the deuteron structure radius r{sub str}=1.975 07(78) fm.

Jentschura, U.D. [Department of Physics, Missouri University of Science and Technology, Rolla, Missouri 65409-0640 (United States); Matveev, A.; Parthey, C.G.; Alnis, J.; Pohl, R.; Udem, Th.; Kolachevsky, N.; Haensch, T.W. [Max-Planck-Institut fuer Quantenoptik, DE-85748 Garching (Germany)

2011-04-15

324

Surface Analysis of Carbon-Hydrogen Bonds in Diamondlike Carbon Films by X-ray Photoelectron Spectroscopy  

NASA Astrophysics Data System (ADS)

X-ray photoelectron spectroscopy (XPS) was used to analyze the carbon-hydrogen bonds near the surfaces of two types of diamondlike carbon (DLC) film with different hydrogen distribution, which were prepared by the unbalanced magnetron sputtering (UBMS) and ionized deposition (ID) methods, respectively. Elastic recoil detection (ERD) analysis revealed that, in the UBMS films, hydrogen is distributed homogeneously along the depth axis, while in the ID film it is distributed inhomogeneously and concentrated at the surface. The C 1s spectra of the UBMS films with different hydrogen concentrations suggested that the spectra are decomposed into four components, corresponding to the carbon-hydrogen and carbon-carbon bonds of the sp2 and sp3 carbons. A correlation between the hydrogen concentrations obtained by the XPS and ERD analyses was observed. The C 1s spectrum of the ID film depended on the emission angle, suggesting that the carbon-hydrogen bonds concentrate at the surface. This result agreed with the ERD result. Both correlations suggested that XPS can analyze hydrogen as an atom bound to a carbon atom and be a comprehensive surface analytical tool for DLC films.

Takabayashi, Susumu; Okamoto, Keishi; Nakatani, Tatsuyuki; Sakaue, Hiroyuki; Takahagi, Takayuki

2009-09-01

325

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

ions.24 Of the ion-molecule probes employed for structural determination, none have been as successful as hydrogen/deuterium (H/D) exchange. This isotope-labeling technique is based upon the exchange of labile hydrogens (i.e. amine, amide, and ?OH... on non-polar, aliphatic amino acids and peptides.39,43,44,45,46 In these systems, the most likely site for protonation is the N- terminal amine, with possible charge site solvation by amide carbonyl groups.47 Although understanding of gas-phase H...

Marini, Joseph Thomas

2004-09-30

326

Hydrogen storage in carbon nanostructures - still a long road from science to commerce?  

NASA Astrophysics Data System (ADS)

Hydrogen storage in carbon nanostructures is still at a research level and not yet mature for industrial application. For the time being it is unfair to compare carbon nanostructures for hydrogen storage at the same level as metal hydrides or other established storage technologies, as not yet enough research has been carried out. Nevertheless we compare carbon nanostructures with well-established hydrogen-storage technologies to develop a feeling of the needs and to identify where bottlenecks might exist. We try to sketch the long route for carbon nanostructures to become a commercial product for hydrogen storage, with a focus on mobile applications.

Bünger, U.; Zittel, W.

2001-04-01

327

Ferromagnetism in hydrogenated N-doped amorphous carbon films  

NASA Astrophysics Data System (ADS)

Room temperature ferromagnetism has been observed in hydrogenated N-doped amorphous carbon films (a-CNx:H) prepared by plasma enhanced chemical vapor deposition. The magnetization of the films changed depending on the ratio (R) of the flow rate of nitrogen to that of methane during deposition and on the annealing temperature. The highest magnetization of the as-deposited samples was obtained with R = 4. Annealing the films at 300 °C resulted in a significant increase in the magnetic moment compared to that of the as-deposited films. When the annealing temperature was above 500 °C, the magnetic moment of the samples decreased. No ferromagnetic impurities could be detected. The ferromagnetism of the a-CNx:H film is attributed mainly to spin-polarization of the p orbitals of the N adatoms on the surface or in the interlayers of irregular carbon.

Liu, S. Y.; Zhen, C. M.; Li, Y. Z.; Pan, C. F.; Zhou, H. J.; Hou, D. L.

2012-03-01

328

X-Ray Emission and Isotopic Shift during Electrochemical Loading of Hydrogen and Deuterium in Palladium and Nickel  

NASA Astrophysics Data System (ADS)

Results from a multi-year, research effort, are summarized. The effort was developed within the framework of a cooperation between ENEA and SRI, and was mainly oriented towards: 1. Performing Electrochemical experiments to investigate the emission of X-rays during electrochemical hydrogen loading of thin metallic films of Pd and Ni, 2. Monitoring the inventory of marker elements in the electrochemical cells, and 3. Replicating experiments involving double structure cathodes, that have been performed previously at SRI and Osaka University, in which heat ^3He and tritium were observed.

Violante, Vittorio; Santoro, E.; Rosada, A.; Sarto, F.; Capobianco, L.; McKubre, Michael; Tanzella, Francis

2003-03-01

329

Simultaneous deuterium implantation and ion beam microanalyses in CFC NB31: Understanding the in-bulk migration  

NASA Astrophysics Data System (ADS)

Understanding the dynamic of in-depth migration and retention of hydrogen in Carbon Fiber Composites (CFCs) used as plasma facing material has for long time been complicated by the lack on in situ analyzing tools. A dedicated experimental setup coupling an ECR ion source to the Saclay nuclear microprobe was developed to expose CFC samples to deuterium implantation at 200-300 eV and fluences from 1022 to 1024 D/m2, and then to perform in situ ?NRA analysis for 3D deuterium profiles. Once the technique proven as non perturbative, we observed that while we have a homogeneous, fluence-independent deuterium concentration at the surface, the in-bulk deuterium is concentrated in the porosities and increases with the incident fluence, up to very large depth (500 ?m). For the first time, it was evidenced that these two distinct mechanisms are simultaneous to the implantation. D profiles evolve very little with in-vacuum storage time.

Bernard, E.; Khodja, H.; Chêne, J.; Pégourié, B.; Martin, C.; Pardanaud, C.

2013-07-01

330

Membrane-based systems for carbon capture and hydrogen purification  

SciTech Connect

This presentation describes the activities being conducted at Los Alamos National Laboratory to develop carbon capture technologies for power systems. This work is aimed at continued development and demonstration of a membrane based pre- and post-combustion carbon capture technology and separation schemes. Our primary work entails the development and demonstration of an innovative membrane technology for pre-combustion capture of carbon dioxide that operates over a broad range of conditions relevant to the power industry while meeting the US DOE's Carbon Sequestration Program goals of 90% CO{sub 2} capture at less than a 10% increase in the cost of energy services. Separating and capturing carbon dioxide from mixed gas streams is a first and critical step in carbon sequestration. To be technically and economically viable, a successful separation method must be applicable to industrially relevant gas streams at realistic temperatures and pressures as well as be compatible with large gas volumes. Our project team is developing polymer membranes based on polybenzimidazole (PBI) chemistries that can purify hydrogen and capture CO{sub 2} at industrially relevant temperatures. Our primary objectives are to develop and demonstrate polymer-based membrane chemistries, structures, deployment platforms, and sealing technologies that achieve the critical combination of high selectivity, high permeability, chemical stability, and mechanical stability all at elevated temperatures (> 150 C) and packaged in a scalable, economically viable, high area density system amenable to incorporation into an advanced Integrated Gasification Combined-Cycle (IGCC) plant for pre-combustion CO{sub 2} capture. Stability requirements are focused on tolerance to the primary synthesis gas components and impurities at various locations in the IGCC process. Since the process stream compositions and conditions (temperature and pressure) vary throughout the IGCC process, the project is focused on the optimization of a technology that could be positioned upstream or downstream of one or more of the water-gas-shift reactors (WGSRs) or integrated with a WGSR.

Berchtold, Kathryn A [Los Alamos National Laboratory

2010-11-24

331

The effect of relatively low hydrogen dilution on the properties of carbon-rich hydrogenated amorphous silicon carbide films  

NASA Astrophysics Data System (ADS)

Carbon-rich hydrogenated amorphous silicon carbide (a-Si1-xCx:H) films were deposited by plasma enhanced chemical vapor deposition (PECVD) using silane, ethylene and hydrogen as gas sources. The effect of relatively low hydrogen dilution on the properties of as-deposited samples was investigated. A variety of techniques including Scanning Electron Microscope (SEM), Fourier transform infrared spectroscopy (FTIR), Raman scattering (RS), UV-VIS spectrophotometer and photoluminescence (PL) spectroscopy were used to characterize the grown films. The deposition rate decreases with hydrogen dilution. The silicon to carbon ratio increases slightly with the addition of hydrogen. The phenomenon can be attributed to the dissipation of power density caused by hydrogen dilution. Raman G peak position shifting to a lower wave number indicates that hydrogen dilution reduces the size and concentration of sp2 carbon clusters, which is caused by the etching effect by atomic hydrogen. The optical band gap, which is controlled by the sp2 carbon clusters and Si/C ratio, changes unmonotonously. The as-deposited samples exhibited a blue-green room-temperature (RT) PL well visible to the naked eye with UV excitation. The PL band can be attributed to the radiative recombination of electron-hole pairs within small sp2 clusters containing C=C and C-H units in a sp3 amorphous matrix.

Li, Zhe; Bian, Juncao; He, Haiyan; Zhang, Xiwen; Han, Gaorong

2011-02-01

332

State-To Chemical Dynamics of the Hydrogen Atom Plus Hydrogen R Groups/deuterium R Groups Goes to Hydrogen/hydrogen Deuteride Plus R Group Hydrogen Abstraction Reactions  

NASA Astrophysics Data System (ADS)

The rotational and vibrational quantum state population distributions of the H_2/HD products of the H + HR/DR to H_2 /HD + R reactions (HD/DR = CD_4, C_2H_6, C _3H_8) have been measured using CARS spectroscopy. Very little of the available energy is partitioned to the H_2 /HD products of these reactions, although more rotational energy is found in the hydrogen product molecule as the size of the R radical increases, f_{ rm int}/f_{rm v}/f_{rm r} is 0.15/0.06/0.09, 0.18/0.06/0.12 and 0.20/0.06/0.14 for the H + CD_4, C_2 H_6, and C_3 H_8 reactions, respectively. Some anomalous behavior is exhibited in the rotational distributions of the reactions. The quantum state distributions show that more rotational energy is partitioned to those molecules formed in v^' = 1, the vibrationally excited state, than is partitioned to the product molecules formed in v^' = 0, the vibrational ground state. Of the energy that is available to produce product rotation 8(15), 11(22) and 12(27)% is partitioned to rotationally excite the H _2/HD product molecules formed in the v^' = 0(v ^' = 1) quantum states in the H + CD_4, C_2H _6, and C_3H _8 reactions, respectively. Finally, the H_2 product quantum state population distributions of the H + C_2H _6 and H + C_3H _8 reactions are observed to become less energetic, both vibrationally and rotationally, more rapidly than the HD product of the H + CD_4 reaction as the H atom reactant is allowed to undergo a greater number of collisions. This final observation could be the result of the differences in structure of the C _2H_6, and C_3H_8 and the CD_4 molecules and/or the differences in the barriers to reaction in each of the reactions.

Germann, Geoffrey James

1990-01-01

333

Single Membrane Reactor Configuration for Separation of Hydrogen, Carbon Dioxide and Hydrogen Sulfide  

SciTech Connect

The objective of the project was to develop a novel complementary membrane reactor process that can consolidate two or more downstream unit operations of a coal gasification system into a single module for production of a pure stream of hydrogen and a pure stream of carbon dioxide. The overall goals were to achieve higher hydrogen production efficiencies, lower capital costs and a smaller overall footprint than what could be achieved by utilizing separate components for each required unit process/operation in conventional coal-to-hydrogen systems. Specifically, this project was to develop a novel membrane reactor process that combines hydrogen sulfide removal, hydrogen separation, carbon dioxide separation and water-gas shift reaction into a single membrane configuration. The carbon monoxide conversion of the water-gas-shift reaction from the coal-derived syngas stream is enhanced by the complementary use of two membranes within a single reactor to separate hydrogen and carbon dioxide. Consequently, hydrogen production efficiency is increased. The single membrane reactor configuration produces a pure H{sub 2} product and a pure CO{sub 2} permeate stream that is ready for sequestration. This project focused on developing a new class of CO{sub 2}-selective membranes for this new process concept. Several approaches to make CO{sub 2}-selective membranes for high-temperature applications have been tested. Membrane disks using the technique of powder pressing and high temperature sintering were successfully fabricated. The powders were either metal oxide or metal carbonate materials. Experiments on CO{sub 2} permeation testing were also performed in the temperature range of 790 to 940 C for the metal carbonate membrane disks. However, no CO{sub 2} permeation rate could be measured, probably due to very slow CO{sub 2} diffusion in the solid state carbonates. To improve the permeation of CO{sub 2}, one approach is to make membranes containing liquid or molten carbonates. Several different types of dual-phase membranes were fabricated and tested for their CO{sub 2} permeation in reducing conditions without the presence of oxygen. Although the flux was quite low, on the order of 0.01-0.001 cc STP/cm{sup 2}/min, the selectivity of CO{sub 2}/He was almost infinite at temperatures of about 800 C. A different type of dual-phase membrane prepared by Arizona State University (ASU) was also tested at GTI for CO{sub 2} permeation. The measured CO{sub 2} fluxes were 0.015 and 0.02 cc STP/cm{sup 2}/min at 750 and 830 C, respectively. These fluxes were higher than the previous flux obtained ({approx}0.01 cc STP/cm{sup 2}/min) using the dual-phase membranes prepared by GTI. Further development in membrane development should be conducted to improve the CO{sub 2} flux. ASU has also focused on high temperature permeation/separation experiments to confirm the carbon dioxide separation capabilities of the dual-phase membranes with La{sup 0.6}Sr{sub 0.4}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}} (LSCF6482) supports infiltrated with a Li/Na/K molten carbonate mixture (42.5/32.5/25.0 mole %). The permeation experiments indicated that the addition of O{sub 2} does improve the permeance of CO{sub 2} through the membrane. A simplified membrane reactor model was developed to evaluate the performance of the process. However, the simplified model did not allow the estimation of membrane transport area, an important parameter for evaluating the feasibility of the proposed membrane reactor technology. As a result, an improved model was developed. Results of the improved membrane reactor model show that the membrane shift reaction has promise as a means to simplify the production of a clean stream of hydrogen and a clean stream of carbon dioxide. The focus of additional development work should address the large area required for the CO{sub 2} membrane as identified in the modeling calculations. Also, a more detailed process flow diagram should be developed that includes integration of cooling and preheating feed streams as well as particulate removal so that stea

Micheal Roberts; Robert Zabransky; Shain Doong; Jerry Lin

2008-05-31

334

Combustion characteristics of hydrogen. Carbon monoxide based gaseous fuels  

NASA Technical Reports Server (NTRS)

An experimental rig program was conducted with the objective of evaluating the combuston performance of a family of fuel gases based on a mixture of hydrogen and carbon monoxide. These gases, in addition to being members of a family, were also representative of those secondary fuels that could be produced from coal by various gasification schemes. In particular, simulated Winkler, Lurgi, and Blue-water low and medium energy content gases were used as fuels in the experimental combustor rig. The combustor used was originally designed as a low NOx rich-lean system for burning liquid fuels with high bound nitrogen levels. When used with the above gaseous fuels this combustor was operated in a lean-lean mode with ultra long residence times. The Blue-water gas was also operated in a rich-lean mode. The results of these tests indicate the possibility of the existence of an 'optimum' gas turbine hydrogen - carbon monoxide based secondary fuel. Such a fuel would exhibit NOx and high efficiency over the entire engine operating range. It would also have sufficient stability range to allow normal light-off and engine acceleration. Solar Turbines Incorporated would like to emphasize that the results presented here have been obtained with experimental rig combustors. The technologies generated could, however, be utilized in future commercial gas turbines.

Notardonato, J. J.; White, D. J.; Kubasco, A. J.; Lecren, R. T.

1981-01-01

335

Combustion characteristics of hydrogen. Carbon monoxide based gaseous fuels  

NASA Astrophysics Data System (ADS)

An experimental rig program was conducted with the objective of evaluating the combuston performance of a family of fuel gases based on a mixture of hydrogen and carbon monoxide. These gases, in addition to being members of a family, were also representative of those secondary fuels that could be produced from coal by various gasification schemes. In particular, simulated Winkler, Lurgi, and Blue-water low and medium energy content gases were used as fuels in the experimental combustor rig. The combustor used was originally designed as a low NOx rich-lean system for burning liquid fuels with high bound nitrogen levels. When used with the above gaseous fuels this combustor was operated in a lean-lean mode with ultra long residence times. The Blue-water gas was also operated in a rich-lean mode. The results of these tests indicate the possibility of the existence of an 'optimum' gas turbine hydrogen - carbon monoxide based secondary fuel. Such a fuel would exhibit NOx and high efficiency over the entire engine operating range. It would also have sufficient stability range to allow normal light-off and engine acceleration. Solar Turbines Incorporated would like to emphasize that the results presented here have been obtained with experimental rig combustors. The technologies generated could, however, be utilized in future commercial gas turbines.

Notardonato, J. J.; White, D. J.; Kubasco, A. J.; Lecren, R. T.

1981-10-01

336

HYBRID HETEROGENEOUS CATALYSTS FOR HYDROGENATION OF CARBON DIOXIDE  

SciTech Connect

HYBRID HETEROGENEOUS CATALYSTS FOR HYDROGENATION OF CARBON DIOXIDE Lucia M. Petkovic, Harry W. Rollins, Daniel M. Ginosar, and Kyle C. Burch Idaho National Laboratory P.O. Box 1625 Idaho Falls, ID 83415-2208 Introduction Anthropogenic emissions of carbon dioxide, a gas often associated with global warming, have increased considerably since the beginning of the industrial age.1 In the U.S., stationary CO2 sources, such as electricity generation plants, produce about one-third of the anthropogenic CO2 generation. Reports2 indicate that the power required to recover 90% of the CO2 from an integrated coal-fired power-plant is about 10% of the power-plant capacity. This energy requirement can be reduced to less than 1% if the recovered CO2 is applied to the production of synthetic fuels. However, the lack of efficient catalysts along with the costs of energy and hydrogen has prevented the development of technologies for direct hydrogenation of CO2.3 Although the cost of hydrogen for hydrogenating CO2 is not economically attractive at present, the future production of hydrogen by nuclear power sources could completely change this scenario.2 Still, an efficient catalyst will be essential for commercial application of those processes. The objective of the work presented here was the development of hybrid catalysts for one-step carbon dioxide hydrogenation to liquid fuels. The hybrid catalysts, which were prepared by two novel techniques, included a copper/zinc oxide catalytic function distributed within an acidic zeolitic matrix. Results of catalyst activity and selectivity studies at atmospheric pressure are presented in this contribution. Experimental Catalysts were prepared by two novel techniques and under several different conditions to produce copper/zinc oxide/zeolite materials. Once synthesized, samples were pelletized and the fraction between 40-60 mesh was utilized for the experiments. Two hundred milligrams of catalyst were loaded in a U-tube stainless steel reactor and a flow of 100 cm3/min of a 10:90 H2:Ar mixture was passed through the catalyst bed while the temperature was increased from room temperature to 513 K at 1.8 K/min and held at 513 K for 15 h. A reactant gas mixture composed by 10 cm3/min of CO2 and 30 cm3/min of H2 was then passed through the catalyst bed and the reaction products monitored by on-line gas chromatographic analyses using an SRI Multiple Gas Analyzer #2 equipped with 3 columns (MoleSieve 13X, Hayesep-D, and MXT-1) and 3 detectors (TCD, FID, and FID-methanizer). This GC system allowed for quantification of inert gases, CO, CO2, methanol, dimethylether, higher alcohols, water, and hydrocarbons up to C20. One hundred milligrams of a commercial syngas-to-methanol catalyst along with the same amount of a commercial zeolite catalyst was utilized under the same reaction conditions for comparison purposes. These catalysts were utilized either in two-layers (Com1) or mixed together (Com2). Results and Discussion Under the conditions applied in this study, the main reaction products were CO, CH3OH, CH3OCH3, and H2O. Methanol and dimethylether production rates and selectivities with respect to CO formation are presented in Figures 1 and 2, respectively. Although the activity of the synthesized catalysts did not surpass the commercial catalysts, the selectivity to oxygenates with respect to CO on most of the synthesized catalysts were better than on the commercial catalysts. For example, cat

Licia M. Petkovic; Harry W. Rollins; Daniel M. Ginosar; Kyle C. Burch

2006-09-01

337

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

DOEpatents

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.

Muradov, Nazim Z. (Melbourne, FL)

2011-08-23

338

Low-molecular-weight carbon nitrides for solar hydrogen evolution.  

PubMed

This work focuses on the control of the polymerization process for melon ("graphitic carbon nitride"), with the aim of improving its photocatalytic activity intrinsically. We demonstrate here that reduction of the synthesis temperature leads to a mixture of the monomer melem and its higher condensates. We show that this mixture can be separated and provide evidence that the higher condensates are isolated oligomers of melem. On evaluating their photocatalytic activity for hydrogen evolution, the oligomers were found to be the most active species, having up to twice the activity of the monomer/oligomer mixture of the as-synthesized material, which in turn has 3 times the activity of the polymer melon, the literature benchmark. These results highlight the role of "defects", i.e., chain terminations, in increasing the catalytic activity of carbon nitrides and at the same time point to the ample potential of intrinsically improving the photocatalytic activity of "carbon nitride", especially through the selective synthesis of the active phase. PMID:25537611

Lau, Vincent Wing-hei; Mesch, Maria B; Duppel, Viola; Blum, Volker; Senker, Jürgen; Lotsch, Bettina V

2015-01-28

339

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

ERIC Educational Resources Information Center

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…

Roddy, Dermot J.

2008-01-01

340

Hydrogen adsorption and cohesive energy of single-walled carbon nanotubes  

Microsoft Academic Search

Hydrogen adsorption on crystalline ropes of carbon single-walled nanotubes (SWNT) was found to exceed 8 wt. %, which is the highest capacity of any carbon material. Hydrogen is first adsorbed on the outer surfaces of the crystalline ropes. At pressures higher than about 40 bar at 80 K, however, a phase transition occurs where there is a separation of the

Y. Ye; C. C. Ahn; C. Witham; B. Fultz; J. Liu; A. G. Rinzler; D. Colbert; K. A. Smith; R. E. Smalley

1999-01-01

341

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...

342

Rapid identification of phase I and II metabolites of artemisinin antimalarials using LTQ-Orbitrap hybrid mass spectrometer in combination with online hydrogen/deuterium exchange technique.  

PubMed

Artemisinin drugs have become the first-line antimalarials in areas of multi-drug resistance. However, monotherapy with artemisinin drugs results in comparatively high recrudescence rates. Autoinduction of CYP-mediated metabolism, resulting in reduced exposure, has been supposed to be the underlying mechanism. To better understand the autoinduction of artemisinin drugs, we evaluated the biotransformation of artemisinin, also known as Qing-hao-su (QHS), and its active derivative dihydroartemisinin (DHA) in vitro and in vivo, using LTQ-Orbitrap hybrid mass spectrometer in conjunction with online hydrogen (H)/deuterium (D) exchange high-resolution (HR)-LC/MS (mass spectrometry) for rapid structural characterization. The LC separation was improved allowing the separation of QHS parent drugs and their metabolites from their diastereomers. Thirteen phase I metabolites of QHS have been identified in liver microsomal incubates, rat urine, bile and plasma, including six deoxyhydroxylated metabolites, five hydroxylated metabolites, one dihydroxylated metabolite and deoxyartemisinin. Twelve phase II metabolites of QHS were detected in rat bile, urine and plasma. DHA underwent similar metabolic pathways, and 13 phase I metabolites and 3 phase II metabolites were detected. Accurate mass data were obtained in both full-scan and MS/MS mode to support assignments of metabolite structures. Online H/D exchange LC-HR/MS experiments provided additional evidence in differentiating deoxydihydroxylated metabolites from mono-hydroxylated metabolites. The results showed that the main phase I metabolites of artemisinin drugs are hydroxylated and deoxyl products, and they will undergo subsequent phase II glucuronidation processes. This study also demonstrated the effectiveness of online H/D exchange LC-HR/MS(n) technique in rapid identification of drug metabolites. PMID:21766391

Liu, Tian; Du, Fuying; Wan, Yakun; Zhu, Fanping; Xing, Jie

2011-08-01

343

Conformation and dynamics of interchain cysteine-linked antibody-drug conjugates as revealed by hydrogen/deuterium exchange mass spectrometry.  

PubMed

Antibody-drug conjugates (ADCs) are protein therapeutics in which a target specific monoclonal antibody (mAb) is conjugated with drug molecules. The manufacturing of ADCs involves additional conjugation steps, which are carried out on the parent mAbs, and it is important to evaluate how the drug conjugation process impacts the conformation and dynamics of the mAb. Here, we present a comparative study of interchain cysteine linked IgG1 ADCs and the corresponding mAb by hydrogen/deuterium exchange mass spectrometry (HDX-MS). We found that ?90% of the primary sequence of the ADC conjugated with either monomethyl auristatin E or F (vcMMAE/mcMMAF) displayed the same HDX kinetics as the mAb, indicating the ADCs and mAbs share very similar conformation and dynamics in solution. Minor increases in HDX kinetic rates were observed in two Fc regions in the ADCs relative to the mAb which indicated that both regions become more structurally dynamic and/or more solvent-accessible in the ADCs. The findings led to a subsequent inquiry into whether the local conformational changes were due to the presence of drugs on the interchain cysteine residues or the absence of intact interchain disulfides or both. To address this question, a side-by-side HDX comparison of ADCs, mAbs, reduced mAbs (containing 8 reduced interchain cysteine thiols), and partially reduced mAbs (conjugation process intermediate) was performed. Our results indicated that the slight increase in conformational dynamics detected at the two regions in the ADCs was due to the absence of intact interchain disulfide bonds and not the presence of vcMMAE or mcMMAF on the alkylated interchain cysteine residues. These results highlight the utility of HDX-MS for interrogating the higher-order structure of ADCs and other protein therapeutics. PMID:24512515

Pan, Lucy Yan; Salas-Solano, Oscar; Valliere-Douglass, John F

2014-03-01

344

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

PubMed

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

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

2012-07-01

345

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

NASA Astrophysics Data System (ADS)

We provide an overview of experimental and theoretical studies on hydrogen storage in single-walled carbon nanotubes (SWNTs) 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 study indicates that 5.1 ± 1.2 wt% hydrogen storage could be achieved by hydrogenation (chemisorption process) of SWNTs. Our computational study shows that chemisorptions of one and two hydrogen atoms on the external surface of (3, 3), (4, 4), (5, 5), and (6, 6) armchair SWNTs are highly exothermic processes. Furthermore, two hydrogen atoms favor to bind at adjacent positions rather than at alternate carbon sites. This is different from the results reported on zigzag nanotubes. The chemisorptions of one and two hydrogen atoms significantly alter the C-C bond lengths of SWNTs in the vicinity of hydrogen addition due to the change of hybridization of carbon atom(s) from sp2 to sp3 at the chemisorption site(s). The effect of increasing the length of SWNTs on the geometries and the reaction energies of hydrogen chemisorption has also been explored. The high exothermicity of the chemisorption of hydrogen atoms on the surface of SWNTs explains the reason for the requirement of high temperature to remove hydrogen from hydrogenated SWNTs.

Dinadayalane, T. C.; Leszczynski, Jerzy

346

Molecular Dynamics Simulation of Hydrogen Storage with Single Walled Carbon Nanotubes  

E-print Network

Molecular Dynamics Simulation of Hydrogen Storage with Single Walled Carbon Nanotubes Shigeo MARUYAMA #12;The hydrogen storage mechanism of SWNTs was studied through molecular dynamics simulations,12) Fig. 6 Hydrogen storage inside each SWNT #12;Table 1 Potential parameters between SWNTs Tube d0 [Ã?

Maruyama, Shigeo

347

Metal-assisted hydrogen storage on Pt-decorated single-walled carbon nanohorns  

E-print Network

Metal-assisted hydrogen storage on Pt-decorated single-walled carbon nanohorns Yun Liu a,b,*, Craig nanoparticles can assist in enhanced hydrogen storage on high-surface area supports are still under debate. Experimental mea- surements of metal-assisted hydrogen storage have been hampered by inaccurate estima- tion

Geohegan, David B.

348

Review of theoretical calculations of hydrogen storage in carbon-based materials  

Microsoft Academic Search

.   In this paper we review the existing theoretical literature on hydrogen storage in single-walled nanotubes and carbon nanofibers.\\u000a The reported calculations indicate a hydrogen uptake smaller than some of the more optimistic experimental results. Furthermore\\u000a the calculations suggest that a variety of complex chemical processes could accompany hydrogen storage and release.

V. Meregalli; M. Parrinello

2001-01-01

349

The Effect of Ion Energy and Substrate Temperature on Deuterium Trapping in Tungsten  

NASA Astrophysics Data System (ADS)

Tungsten is a candidate plasma facing material for next generation magnetic fusion devices such as ITER and there are major operational and safety issues associated with hydrogen (tritium) retention in plasma facing components. An ion gun was used to simulate plasma-material interactions under various conditions in order to study hydrogen retention characteristics of tungsten thus enabling better predictions of hydrogen retention in ITER. Thermal Desorption Spectroscopy (TDS) was used to measure deuterium retention from ion irradiation while modelling of TDS spectra with the Tritium Migration Analysis Program (TMAP) was used to provide information about the trapping mechanisms involved in deuterium retention in tungsten. X-ray Photoelectron Spectroscopy (XPS) and Secondary Ion Mass Spectrometry (SIMS) were used to determine the depth resolved composition of specimens used for irradiation experiments. Carbon and oxygen atoms will be among the most common contaminants within ITER. C and O contamination in polycrystalline tungsten (PCW) specimens even at low levels (˜0.1%) was shown to reduce deuterium retention by preventing diffusion of deuterium into the bulk of the specimen. This diffusion barrier was also responsible for the inhibition of blister formation during irradiations at 500 K. These observations may provide possible mitigation techniques for problems associated with tritium retention and mechanical damage to plasma facing components caused by hydrogen implantation. Deuterium trapping in PCW and single crystal tungsten (SCW) was studied as a function of ion energy and substrate temperature. Deuterium retention was shown to decrease with decreasing ion energy below 100 eV/D+. Irradiation of tungsten specimens with 10 eV/D+ ions was shown to retain up to an order of magnitude less deuterium than irradiation with 500 eV/D+ ions. Furthermore, the retention mechanism for deuterium was shown to be consistent across the entire energy range studied (10-500 eV) with the shallow penetration depth of low energy ions being the major factor in the reduction in retention. A change in retention mechanism was observed as tungsten temperature during irradiation was increased from 300 to 500 K. Modelling of deuterium retention in 300 and 500 K SCW specimens revealed that two traps, 1.0 and 1.3 eV, are involved in retention for irradiations performed at 300K while a single 2.1 eV trap is present for 500 K irradiations. Experiments suggest that the 2.1 eV trap is created during irradiation of tungsten at 500 K and this process also involves the annihilation of the 1.3 and 1.0 eV traps.

Roszell, John Patrick Town

350

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

DOEpatents

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.

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

2008-11-18

351

Hydrogen induced redox mechanism in amorphous carbon resistive random access memory  

PubMed Central

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

2014-01-01

352

Catalytic Metal Free Production of Large Cage Structure Carbon Particles: A Candidate for Hydrogen Storage  

NASA Technical Reports Server (NTRS)

We will demonstrate that carbon particles consisting of large cages can be produced without catalytic metal. The carbon particles were produced in CO gas as well as by introduction of 5% methane gas into the CO gas. The gas-produced carbon particles were able to absorb approximately 16.2 wt% of hydrogen. This value is 2.5 times higher than the 6.5 wt% goal for the vehicular hydrogen storage proposed by the Department of Energy in the USA. Therefore, we believe that this carbon particle is an excellent candidate for hydrogen storage for fuel cells.

Kimura, Yuki; Nuth, Joseph A., III; Ferguson, Frank T.

2005-01-01

353

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

354

Sustainable production of green feed from carbon dioxide and hydrogen.  

PubMed

Carbon dioxide hydrogenation to form hydrocarbons was conducted on two iron-based catalysts, prepared according to procedures described in the literature, and on a new iron spinel catalyst. The CO2 conversion measured in a packed-bed reactor was limited to about 60% because of excessive amounts of water produced in this process. Switching to a system of three packed-bed reactors in series with interim removal of water and condensed hydrocarbons increased CO2 conversion to as much as 89%. The pure spinel catalyst displayed a significantly higher activity and selectivity than those of the other iron catalysts. This process produces a product called green feed, which is similar in composition to the product of a high-temperature, iron-based Fischer–Tropsch process from syngas. The green feed can be readily converted into renewable fuels by well-established technologies. PMID:24678062

Landau, Miron V; Vidruk, Roxana; Herskowitz, Moti

2014-03-01

355

Systematic study of amorphous hydrogenated and fluorinated carbon films  

NASA Astrophysics Data System (ADS)

Amorphous fluorinated carbon films were grown from CF 4 and C 2H 2 mixtures, using a Plasma Assisted Chemical Vapour Deposition (PACVD) apparatus. Two sets of films were deposited, changing in a systematic way the CF 4 flux and the bias voltage ( Vb). Film composition and structure were analysed by secondary ion mass spectroscopy (SIMS), infrared (IR) and Raman spectroscopies. Film hardness was obtained by micro-indentation measurements. On increasing fluorine content in films, hardness decreases and a fluorescence background in Raman spectra appears at high fluorine content, showing a diamond- to polymer-like structural transition. Infrared spectra indicate the presence of ?CF x, C?CHF and C?CF 2 groups in the films. Our data are compared with previous results in the literature and the mechanisms involved in film formation are discussed, especially regarding fluorine substitution for hydrogen.

Lamperti, A.; Ossi, P. M.

2003-01-01

356

Apparatus for hydrogen and carbon production via carbon aerosol-catalyzed dissociation of hydrocarbons  

NASA Technical Reports Server (NTRS)

A novel process and apparatus is disclosed for sustainable, continuous production of hydrogen and carbon by catalytic dissociation or decomposition of hydrocarbons at elevated temperatures using in-situ generated carbon particles. Carbon particles are produced by decomposition of carbonaceous materials in response to an energy input. The energy input can be provided by at least one of a non-oxidative and oxidative means. The non-oxidative means of the energy input includes a high temperature source, or different types of plasma, such as, thermal, non-thermal, microwave, corona discharge, glow discharge, dielectric barrier discharge, or radiation sources, such as, electron beam, gamma, ultraviolet (UV). The oxidative means of the energy input includes oxygen, air, ozone, nitrous oxide (NO.sub.2) and other oxidizing agents. The method, apparatus and process of the present invention is applicable to any gaseous or liquid hydrocarbon fuel and it produces no or significantly less CO.sub.2 emissions compared to conventional processes.

Muradov, Nazim Z. (Inventor); Smith, Franklyn (Inventor); Tabatabaie-Raissi, Ali (Inventor)

2012-01-01

357

Kinetic modelling of molecular hydrogen transport in microporous carbon materials.  

SciTech Connect

The proposal of kinetic molecular sieving of hydrogen isotopes is explored by employing statistical rate theory methods to describe the kinetics of molecular hydrogen transport in model microporous carbon structures. A Lennard-Jones atom-atom interaction potential is utilized for the description of the interactions between H{sub 2}/D{sub 2} and the carbon framework, while the requisite partition functions describing the thermal flux of molecules through the transition state are calculated quantum mechanically in view of the low temperatures involved in the proposed kinetic molecular sieving application. Predicted kinetic isotope effects for initial passage from the gas phase into the first pore mouth are consistent with expectations from previous modeling studies, namely, that at sufficiently low temperatures and for sufficiently narrow pore mouths D{sub 2} transport is dramatically favored over H{sub 2}. However, in contrast to expectations from previous modeling, the absence of any potential barrier along the minimum energy pathway from the gas phase into the first pore mouth yields a negative temperature dependence in the predicted absolute rate coefficients - implying a negative activation energy. In pursuit of the effective activation barrier, we find that the minimum potential in the cavity is significantly higher than in the pore mouth for nanotube-shaped models, throwing into question the common assumption that passage through the pore mouths should be the rate-determining step. Our results suggest a new mechanism that, depending on the size and shape of the cavity, the thermal activation barrier may lie in the cavity rather than at the pore mouth. As a consequence, design strategies for achieving quantum-mediated kinetic molecular sieving of H{sub 2}/D{sub 2} in a microporous membrane will need, at the very least, to take careful account of cavity shape and size in addition to pore-mouth size in order to ensure that the selective step, namely passage through the pore mouth, is also the rate determining step.

Hankel, M.; Zhang, H.; Nguyen, T. X.; Bhatia, S. K.; Gray, S. K.; Smith, S. C. (Center for Nanoscale Materials); (The Univ. of Queensland)

2011-01-01

358

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

Microsoft Academic Search

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

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

2007-01-01

359

Role of Nonmetallic Inclusions in Hydrogen Embrittlement of High-Strength Carbon Steels with Different Microalloying  

NASA Astrophysics Data System (ADS)

High-strength carbon steels of 1200 MPa strength level with different microalloying were tensile tested at constant extension rate and constant load under continuous electrochemical hydrogen charging. The results show that hydrogen markedly reduces elongation and time to fracture of all the studied steels. Fractography of the steels shows that nonmetallic inclusions (NMIs) play the major role in crack initiation in hydrogen-charged specimens. The role of NMIs in the hydrogen-induced fracture of steels is discussed.

Todoshchenko, Olga Madelen Ingrid; Yagodzinskyy, Yuriy; Saukkonen, Tapio; Hänninen, Hannu

2014-10-01

360

Thermodynamic analysis of Glycerol Steam Reforming for hydrogen production with in situ hydrogen and carbon dioxide separation  

NASA Astrophysics Data System (ADS)

A thermodynamic study of Glycerol Steam Reforming (GSR) for hydrogen production with in situ carbon dioxide and hydrogen (reaction products) simultaneous removal was performed. The sorption-enhanced membrane reactor (SEMR) was divided into multiple sub-Gibbs reactors and the Gibbs free energy minimization method was employed. The effects of temperature (600-800 K), molar water-to-glycerol feed ratio (WGFR) (3-9), pressure (1-5 atm) and fraction of hydrogen and carbon dioxide removal (f, 0-0.99) on the GSR process were target of investigation. A hydrogen yield (total moles of hydrogen produced/mole of reacted glycerol) very close to the stoichiometric value of 7 was obtained at 700 K, WGFR of 9, 1 atm and for fCO2 = 0.99 and fH2 = 0.80. This corresponds to an enhancement of 217%, 47% and 22% in terms of hydrogen yield comparatively to the traditional reactor (TR), sorption-enhanced reactor (SER) with carbon dioxide capture (fCO2 = 0.99) and membrane reactor (MR) with hydrogen separation (fH2 = 0.80) , respectively. In terms of coke, its formation was only observed under WGFRs below the stoichiometric value of 3.

Silva, Joel M.; Soria, M. A.; Madeira, Luis M.

2015-01-01

361

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

DOEpatents

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.

Marling, John B. (Livermore, CA)

1981-01-01

362

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

E-print Network

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

Cal, Mark P.

363

Concomitant Production of High Purity Hydrogen and Sequestration Ready Carbon Dioxide From Coal  

Microsoft Academic Search

A novel process on the production of a high purity stream of hydrogen from gasification products with concomitant generation of sequestration-ready carbon dioxide stream is presented. The central theme of the process lies in the sequential use of a) an oxygen transfer compound (OTC) to oxidize carbon monoxide present in syngas and b) capture of CO2 using an appropriate carbon

Kanchan Mondal; Krzysztof Piotrowski; Tomasz Wiltowski

364

Ultra-high-yield growth of vertical single-walled carbon nanotubes: Hidden roles of hydrogen  

E-print Network

Ultra-high-yield growth of vertical single-walled carbon nanotubes: Hidden roles of hydrogen to afford large-scale, highly reproducible, ultra-high-yield growth of vertical single-walled carbon been developed to grow vertically aligned multiwalled carbon nanotubes, growth of ver- tical single

Zhang, Guangyu

365

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

E-print Network

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

Abdou, Hanan E.

366

Study of Hydrogen Adsorption by Spiral Carbon Nano Fibers Synthesized From Acetylene  

Microsoft Academic Search

A spiral carbon nanofiber of 30 to 40 nm diam and 20 µm average lengths has been synthesized by catalyst chemical vapor deposition method using Ni or Fe?Ni alloy as catalyst. The purpose of synthesis of carbon nano fibers was to use it for hydrogen adsorption. Catalysts used affected the morphology of carbon nano material (CNM) where as purification and ball milling

Sandesh V. Jaybhaye; Maheshwar Sharon; Madhuri Sharon; L. N. Singh

2006-01-01

367

Effect of Hydrogen Content on Threshold Stress Intensity Factor in Carbon Steel in Hydrogen-Assisted Cracking Environments  

Microsoft Academic Search

Crack propagation of carbon steel (CS) caused by hydrogen in an overprotective buffer solution environment was investigated to determine the threshold stress intensity factor (K{sub IH}) for hydrogen assisted-cracking (HAC) using a wedge open-load (WOL) specimen. The K-value decreasing-type testing method was adopted as the experimental method. The possibility of crack propagation by cathodic protection (CP) in the soil environment

Y. Yamaguchi; K. Yamakawa; H. Nonaka

1997-01-01

368

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

NASA Astrophysics Data System (ADS)

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.

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

369

Dynamic and static deuterium inventory in ASDEX Upgrade with tungsten first wall  

NASA Astrophysics Data System (ADS)

Hydrogen retention in the divertor tokamak ASDEX Upgrade is studied by surface analysis and gas balances methods. Comparing carbon and tungsten plasma facing components (PFCs), the deuterium content of deposits at the divertor plates has dropped by a factor of 13. With tungsten PFCs only 0.7% of the puffed hydrogen is retained, including a significant amount deeply implanted in the tungsten coatings at the outer divertor. Gas balances for ITER relevant high density H-mode discharges lead to a hydrogen retention averaged over a discharge of 8.2 ± 3.3% for tungsten PFCs and 23 ± 7% for carbon PFCs. For tungsten PFCs wall saturation is observed, i.e. only 1.5 ± 3.5% of the puffed gas is retained after reaching steady state conditions. Within the error bars all hydrogen outgasses within 15 min.

Rohde, V.; Mayer, M.; Mertens, V.; Neu, R.; Sugiyama, K.; ASDEX Upgrade Team

2009-08-01

370

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

DOEpatents

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.

Detering, Brent A.; Kong, Peter C.

2006-08-29

371

Transfer of Rovibrational Energies in Hydrogen Plasma-Carbon Surface Interactions  

SciTech Connect

We present state-of-the-art molecular dynamics (MD) simulations of high-density plasma-bombardment of carbon, mimicking plasma-wall interactions at the fusion reactor first wall. Bare and hydrogenated amorphous carbon surfaces with temperatures in the range of 300-800K are bombarded by a distribution of neutral hydrogen molecules representing well defined center-of-mass and rovibrational temperatures. The MD simulations are benchmarked against experiments in which a heated carbon surface is irradiated with hydrogen molecules from a plasma source. Comparisons between simulations and experiment are presented for the rovibrational distributions upon reflection and the rotational and vibrational accommodation coefficients.

Krstic, Predrag S [ORNL; Hollmann, E. M. [University of California, San Diego; Reinhold, Carlos O [ORNL; Stuart, S. J. [Clemson University; Doerner, R. P. [University of California, San Diego; Nishijima, D. [University of California, San Diego; Pigarov, A. Yu. [University of California, San Diego

2009-01-01

372

Molecular dynamics simulation of erosion and surface evolution of tungsten due to bombardment with deuterium and carbon in  

E-print Network

t i c l e i n f o Article history: Received 8 March 2013 Received in revised form 13 May 2013 atoms can migrate to other places and re-deposit on tungsten sur- face to form thin carbon film and remove tungsten atoms from the surface. The deposited carbon on tungsten surface increases hydro- gen

Harilal, S. S.

373

Minimisation of carbon monoxide in a hydrogen stream for fuel cell application  

Microsoft Academic Search

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

D. L. Trimm

2005-01-01

374

Hydrogen storage capacity of carbon nanotubes, filaments, and vapor-grown fibers  

Microsoft Academic Search

We have studied the sorption of hydrogen by nine different carbon materials at pressures up to 11 MPa (1600 psi) and temperatures from ?80 to +500°C. Our samples include graphite particles, activated carbon, graphitized PYROGRAF vapor-grown carbon fibers (VGCF), CO2 and air-etched PYROGRAF fibers, Showa-Denko VGCF, carbon filaments grown from a FeNiCu alloy, and nanotubes from MER Corp. and Rice

Gary G Tibbetts; Gregory P Meisner; Charles H Olk

2001-01-01

375

REMOVAL OF HYDROGEN SULFIDE, AMMONIA AND NITRITE IONS FROM WATER SOLUTIONS USING MODIFIED ACTIVE CARBONS  

Microsoft Academic Search

Modified active carbons were used for removal of hydrogen sulfide, ammonia and nitrite ions from water solutions. Obtained\\u000a results demonstrate that active carbon oxidized with H2O2 following impregnation with Co(II) possesses higher adsorption capacity for NH4\\u000a + compared with unimpregnated samples. It was established that active carbon obtained from nut shells has better oxidation\\u000a properties compared with active carbons obtained

T. LUPASCU; RAISA NASTAS; M. CIOBANU; TATIANA ARAPU; V. RUSU

376

Molten metal reactor and method of forming hydrogen, carbon monoxide and carbon dioxide using the molten alkaline metal reactor  

SciTech Connect

A molten metal reactor for converting a carbon material and steam into a gas comprising hydrogen, carbon monoxide, and carbon dioxide is disclosed. The reactor includes an interior crucible having a portion contained within an exterior crucible. The interior crucible includes an inlet and an outlet; the outlet leads to the exterior crucible and may comprise a diffuser. The exterior crucible may contain a molten alkaline metal compound. Contained between the exterior crucible and the interior crucible is at least one baffle.

Bingham, Dennis N.; Klingler, Kerry M.; Turner, Terry D.; Wilding, Bruce M.

2012-11-13

377

Piezoresistive gauge factor of hydrogenated amorphous carbon films  

NASA Astrophysics Data System (ADS)

In this paper we report on the transport properties of hydrogenated amorphous carbon (a-C:H) which is an attractive material for strain gauges and can also be used in flow meters, accelerometers and vibrational sensors. The a-C:H films were deposited at -350 V bias voltage on silicon (Si) substrates using plasma assisted chemical vapor deposition (PACVD). Current-voltage characteristics of a-C:H/n-Si heterojunctions show ohmic behavior within operating voltages of ±1 V. In the higher voltage range the Frenkel-Poole mechanism is dominant. Conduction is thermally activated at temperatures ranging from 23 °C to 150 °C. The activation energy amounts to 0.48 eV. A-C:H resistors are successfully integrated as strain gauges in Si bulk micromachined force sensors. Piezoresistive gauge factors are measured for the a-C:H strain gauge resistors in the temperature range 23-60 °C. The measured piezoresistive gauge factors are in between 40 and 90 for a-C:H with resistivities in the range 100-700 M? cm.

Tibrewala, A.; Peiner, E.; Bandorf, R.; Biehl, S.; Lüthje, H.

2006-06-01

378

Multilayer Adsorption of Neon, Hydrogens, and Carbon Monoxide on Graphite.  

NASA Astrophysics Data System (ADS)

Multilayer adsorption of neon, hydrogens (H _2, HD, and D_2), and carbon monoxide on graphite have been investigated using ellipsometric-coverage vapor-pressure isotherm measurements. Chemical potentials at layer condensations and widths of the layer condensation steps were tabulated, and layer critical points were determined from the temperature dependence of the widths for all five adsorbates. In Ne we do not find evidence for reentrant first -order layering, which was previously found in Ar, Kr, and Xe. The adsorption behavior on graphite of H_2, HD, and D_2 is very similar. We observed temperature-dependent splitting and hysteresis in the fourth, fifth, and sixth layers in all three adsorbates. This may suggest structure changes, possibly between face-centered cubic and hexagonal closed-packed stacking, in these layers. In CO, below the bulk alpha- beta transition temperature, we have seen incomplete wetting with a series of layer-appearance transitions from the third to the tenth layer. Above the alpha-beta transition temperature, the thickness of the film remains around 11 layers. We observed reentrant first-order layering in the condensation of the fourth layer in CO. But the broadening feature is much weaker compared to Ar, Kr, and Xe, and is not observed at all in the higher layers.

Wu, Hong

1995-11-01

379

Ellipsometric and optical study of amorphous hydrogenated carbon films  

NASA Technical Reports Server (NTRS)

A low-frequency plasma deposition system was used to prepare amorphous hydrogenated carbon (a-C:H) films. The growth energy was varied by changing the power and/or pressure of the plasma. Ellipsometry and optical absorption were used to obtain the optical energy gap, the density of states, and the refractive index. Ion sputtering was used in conjunction with ellipsometry and Auger electron spectroscopy to get absolute sputtering rates. The plasma deposited a-C:H is amorphous with an optical energy gap of approximately 2.0-2.4 eV. These a-C:H films have higher density and/or hardness, higher refractive index, and lower optical energy gaps with increasing energy of the particles in the plasma, while the density of states remains unchanged. These results are in agreement with, and give a fine-tuned positive confirmation to, an existing conjecture on the nature of the a-C:H films (Kaplan et al., 1985).

Alterovitz, S. A.; Warner, J. D.; Liu, D. C.; Pouch, J. J.

1986-01-01

380

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...

381

Controlled cutting and hydroxyl functionalization of carbon nanotubes through autoclaving and sonication in hydrogen peroxide.  

PubMed

In this study, an eco-friendly process utilizing a low concentration of hydrogen peroxide along with autoclaving and sonication was developed, accomplishing both carbon nanotube size reduction and hydroxyl functionalization. PMID:25736168

Weydemeyer, Ethan J; Sawdon, Alicia J; Peng, Ching-An

2015-04-01

382

Realizing a Carbon-Based Hydrogen Storage Material  

Microsoft Academic Search

In response to the current need for an efficient, safe, and compact system for storing hydrogen in mobile applications, a scheme for maximizing and controlling hydrogen storage in graphite is proposed by modifying substrate reactivity through the exploitation of intrinsic vibrational modes in pristine and fully-hydrogenated graphite systems. Calculations within density functional theory suggest that infrared radiation of distinct frequencies

Tanglaw Roman; Wilson Agerico Di no; Hiroshi Nakanishi; Hideaki Kasai; Tsuyoshi Sugimoto; Kyouichi Tange

2006-01-01

383

Tribological studies of amorphous hydrogenated carbon films in a vacuum, spacelike environment  

NASA Technical Reports Server (NTRS)

Recent work on the adhesion and friction properties of plasma-deposited amorphous hydrogenated 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) exhibiting diamondlike friction behavior. The plasma-deposited a-C:H films can be effectively used as hard lubricating films on ceramic materials such as silicon nitride in vacuum.

Miyoshi, Kazuhisa

1991-01-01

384

Effects of palladium coating on field-emission properties of carbon nanofibers in a hydrogen plasma  

E-print Network

Effects of palladium coating on field-emission properties of carbon nanofibers in a hydrogen plasma. Following exposure to a hydrogen plasma for sev- eral hours we find that the coatings impede plasma damage nm) and titanium (30 nm) layers as a base, and a pat- terned nickel layer as a catalyst. The copper

Javey, Ali

385

Design and Development of New Carbon-Based Sorbent Systems for an Effective Containment of Hydrogen  

SciTech Connect

This is a summary for work performed under cooperative agreement DE FC36 04GO14006 (Design and Development of New Carbon-based Sorbent Systems for an Effective Containment of Hydrogen). The project was directed to discover new solid and liquid materials that use reversible catalytic hydrogenation as the mechanism for hydrogen capture and storage. After a short period of investigation of solid materials, the inherent advantages of storing and transporting hydrogen using liquid-phase materials focused our attention exclusively on organic liquid hydrogen carriers (liquid carriers). While liquid carriers such as decalin and methylcyclohexane were known in the literature, these carriers suffer from practical disadvantages such as the need for very high temperatures to release hydrogen from the carriers and difficult separation of the carriers from the hydrogen. In this project, we were successful in using the prediction of reaction thermodynamics to discover liquid carriers that operate at temperatures up to 150 C lower than the previously known carriers. The means for modifying the thermodynamics of liquid carriers involved the use of certain molecular structures and incorporation of elements other than carbon into the carrier structure. The temperature decrease due to the more favorable reaction thermodynamics results in less energy input to release hydrogen from the carriers. For the first time, the catalytic reaction required to release hydrogen from the carriers could be conducted with the carrier remaining in the liquid phase. This has the beneficial effect of providing a simple means to separate the hydrogen from the carrier.

Alan C. Cooper

2012-05-03

386

Hydrogen peroxide adsorption on Fe-filled single-walled carbon nanotubes: a theoretical study  

NASA Astrophysics Data System (ADS)

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 (H2O2) 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).

Moreno, J.; Kasai, K.; David, M.; Nakanishi, H.; Kasai, H.

2009-02-01

387

Hydrogen peroxide adsorption on Fe-filled single-walled carbon nanotubes: a theoretical study.  

PubMed

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

Moreno, J; Kasai, K; David, M; Nakanishi, H; Kasai, H

2009-02-11

388

Hydrogen isotope discrimination in higher plants: Correlations with photosynthetic pathway and environment  

Microsoft Academic Search

The ratio of deuterium to hydrogen (expressed as dD) in hydrogen released as water during the combustion of dried plant material was examined. The dD value (metabolic hydrogen) determined on plant materials grown under controlled conditions is correlated with pathways of photosynthetic carbon metabolism. C3 plants show mean dD values of-132‰ for shoots and -117‰ for roots; C4 plants show

H. Ziegler; C. B. Osmond; W. Stichler; P. Trimborn

1976-01-01

389

Migration mechanism for atomic hydrogen in porous carbon materials Badri Narayanan,1  

E-print Network

Migration mechanism for atomic hydrogen in porous carbon materials Badri Narayanan,1 Yufeng Zhao,2 by the porous nature of the material itself. The mechanism proposed is applicable for any porous carbon CNTs: the H-diffusion is thus facilitated by the porous nature of the material itself, which allows

Ciobanu, Cristian

390

Growth of Nanoscale Carbon Structures and Their Corresponding Hydrogen Uptake Properties  

Microsoft Academic Search

Carbon nanostructures have been synthesized using the chemical vapor deposition technique (CVD) on different catalysts, using ethylene, acetylene, or methane as the hydrocarbons. Morphological characterizations obtained using a scanning electron microscope (SEM) showed that the reaction products are carbon nanofibers (CNF) with an outer diameter that depends on the reaction conditions and nature of the reactants. Hydrogen uptake measurements, performed

D. LUPU; A. R. BIRIS; I. MISAN; N. LUPSA; A. S. BIRIS; D. A. BUZATU; M. KLEEVE

2002-01-01

391

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

E-print Network

Single Pd atoms in activated carbon fibers and their contribution to hydrogen storage 5 Cristian I, Department of Physics, Richmond, VA 23284, USA A R T I C L E I N F O Article history: Received 20 December atoms occurring in the carbon matrix that coexist with larger Pd particles. First principles

Pennycook, Steve

392

Cometary deuterium.  

PubMed

Deuterium fractionations in cometary ices provide important clues to the origin and evolution of comets. Mass spectrometers aboard spaceprobe Giotto revealed the first accurate D/H ratios in the water of Comet 1P/Halley. Ground-based observations of HDO in Comets C/1996 B2 (Hyakutake) and C/1995 O1 (Hale-Bopp), the detection of DCN in Comet Hale-Bopp, and upper limits for several other D-bearing molecules complement our limited sample of D/H measurements. On the basis of this data set all Oort cloud comets seem to exhibit a similar (D/H)H2O ratio in H2O, enriched by about a factor of two relative to terrestrial water and approximately one order of magnitude relative to the protosolar value. Oort cloud comets, and by inference also classical short-period comets derived from the Kuiper Belt cannot be the only source for the Earth's oceans. The cometary O/C ratio and dynamical reasons make it difficult to defend an early influx of icy planetesimals from the Jupiter zone to the early Earth. D/H measurements of OH groups in phyllosilicate rich meteorites suggest a mixture of cometary water and water adsorbed from the nebula by the rocky grains that formed the bulk of the Earth may be responsible for the terrestrial D/H. The D/H ratio in cometary HCN is 7 times higher than the value in cometary H2O. Species-dependent D-fractionations occur at low temperatures and low gas densities via ion-molecule or grain-surface reactions and cannot be explained by a pure solar nebula chemistry. It is plausible that cometary volatiles preserved the interstellar D fractionation. The observed D abundances set a lower limit to the formation temperature of (30 +/- 10) K. Similar numbers can he derived from the ortho-to-para ratio in cometary water, from the absence of neon in cometary ices and the presence of S2. Noble gases on Earth and Mars, and the relative abundance of cometary hydrocarbons place the comet formation temperature near 50 K. So far all cometary D/H measurements refer to bulk compositions, and it is conceivable that significant departures from the mean value could occur at the grain-size level. Strong isotope effects as a result of coma chemistry can be excluded for molecules H2O and HCN. A comparison of the cometary (D/H)H2O ratio with values found in the atmospheres of the outer planets is consistent with the long-held idea that the gas planets formed around icy cores with a high cometary D/H ratio and subsequently accumulated significant amounts of H2 from the solar nebula with a low protosolar D/H. PMID:11543290

Meier, R; Owen, T C

1999-01-01

393

Thermally Controlled Hydrogen Storage System Using Novel Carbon Materials  

Microsoft Academic Search

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

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

394

Effects of hydrogen on carbon steels at the Multi-Function Waste Tank Facility  

SciTech Connect

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.

Carlos, W.C.

1995-02-08

395

Direct and reversible hydrogenation of CO2 to formate by a bacterial carbon dioxide reductase.  

PubMed

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

Schuchmann, K; Müller, V

2013-12-13

396

Effective and efficient purification of single-wall carbon nanotubes based on hydrogen treatment  

NASA Astrophysics Data System (ADS)

A simple, effective and efficient purification method for single-wall carbon nanotubes (SWCNTs) prepared by hydrogen arc discharge has been developed. Hydrogen treatment has been used to remove the amorphous carbon and graphene sheets encapsulating Fe catalyst nanoparticles. The exposed Fe nanoparticles can be easily dissolved in concentrated hydrochloric acid. Carbon content higher than 99 wt.% can be achieved. The small SWCNTs with a diameter of 0.9 nm are found to survive during the purification processes. This new purification method enables us to obtain purified SWCNTs with high-crystallinity and without obvious damage.

Sheng, Leimei; Shi, Lei; An, Kang; Yu, Liming; Ando, Yoshinori; Zhao, Xinluo

2011-01-01

397

Carbide-Derived Carbons with Tunable Porosity Optimized for Hydrogen Storage  

SciTech Connect

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. In this project a systematic study of carbide-derived carbons, a novel form of porous carbon, was carried out to discover a high-performance hydrogen sorption material to meet the goal. In the event we were unable to improve on the state of the art in terms of stored hydrogen per unit weight, having encountered the same fundamental limit of all porous carbons: the very weak interaction between H2 and the carbon surface. On the other hand we did discover several strategies to improve storage capacity on a volume basis, which should be applicable to other forms of porous carbon. Further discoveries with potentially broader impacts include • Proof that storage performance is not directly related to pore surface area, as had been previously claimed. Small pores (< 1.5 nm) are much more effective in storing hydrogen than larger ones, such that many materials with large total surface areas are sub-par performers. • Established that the distribution of pore sizes can be controlled during CDC synthesis, which opens the possibility of developing high performance materials within a common family while targeting widely disparate applications. Examples being actively pursued with other funding sources include methane storage, electrode materials for batteries and supercapacitors with record high specific capacitance, and perm-selective membranes which bind cytokines for control of infections and possibly hemodialysis filters.

Fisher, John E.; Gogotsi, Yury; Yildirim, Taner

2010-01-07

398

Preparation and hydrogen storage of activated rayon-based carbon fibers with high specific surface area  

Microsoft Academic Search

Activated carbon fibers were prepared from rayon-based carbon fibers by two step activations with steam and KOH treatments. Hydrogen storage properties of the activated rayon-based carbon fibers with high specific surface area and micropore volume have been investigated. SEM, XRD and Brunauer–Emmett–Teller (BET) were used to characterize the samples. The adsorption performance and porous structure were investigated by nitrogen adsorption

Fen Gao; Dong-Lin Zhao; Yan Li; Xing-Guo Li

2010-01-01

399

Synthesis of sulfur-containing heterocycles through oxidative carbon-hydrogen bond functionalization.  

PubMed

Vinyl sulfides react rapidly and efficiently with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) to form ?,?-unsaturated thiocarbenium ions through oxidative carbon-hydrogen bond cleavage. These electrophiles couple with appended ?-nucleophiles to yield sulfur-containing heterocycles through carbon-carbon bond formation. Several nucleophiles are compatible with the procedure, and the reactions generally proceed through readily predictable transition states. PMID:22420412

Cui, Yubo; Floreancig, Paul E

2012-04-01

400

Unmodified versus caustics-impregnated carbons for control of hydrogen sulfide emissions from sewage treatment plants  

Microsoft Academic Search

Unmodified and caustic-impregnated carbons were compared as adsorbents for hydrogen sulfide in the North River Water Pollution Control Plant in New York City over a period of 2 years. The carbons were characterized using accelerated HâS breakthrough capacity tests, sorption of nitrogen, potentiometric titration, and thermal analysis. The accelerated laboratory tests indicate that the initial capacity of caustic-impregnated carbons exceeds

Teresa J. Bandosz; Andrey Bagreev; Foad Adib; Amos Turk

2000-01-01

401

HYDROGEN ISOTOPE PROFILE OF METHYL GROUPS IN MILIACIN (OLEAN-18-EN-3OL ME) BY NATURAL ABUNDANCE DEUTERIUM 2D-NMR  

E-print Network

HYDROGEN ISOTOPE PROFILE OF METHYL GROUPS IN MILIACIN (OLEAN- 18-EN-3OL ME) BY NATURAL ABUNDANCE.lesot@u-psud.fr; jeremy.jacob@univ-orleans.fr Compound-specific hydrogen isotope analyses are gaining increasing interest to which extent these modifications can be accompanied by a hydrogen isotope fractionation process

Paris-Sud XI, Université de

402

Shock Compression of Deuterium and the Interiors of Jupiter and Saturn  

Microsoft Academic Search

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)

D. Saumon; T. Guillot

2004-01-01

403

Carbon-carbon bond formation pathways in CO hydrogenation to higher alcohols  

SciTech Connect

Carbon-carbon bond formation pathways during CO hydrogenation to higher alcohols were studied on alkali-promoted Cu-based catalysts (K-CuMgCeO{sub x} and Cs-Cu/ZnO/Al{sub 2}O{sub 3}) using {sup 13}CO/H{sub 2}/{sup 12}CH{sub 3}OH reactants. C-C bonds in ethanol form via two pathways, direct reactions of {sup 13}CO and direct coupling of {sup 12}CH{sub 3}OH. On K-CU{sub 0.5}Mg{sub 5}CeO{sub x}, direct reactions of {sup 13}CO are the predominant pathway for the initial C-C bond steps. On Cs-Cu/ZnO/Al{sub 2}O{sub 3}, ethanol is predominantly formed via direct coupling of oxygen-containing C{sub 1} intermediates derived from {sup 12}CH{sub 3}OH. Ca{sup +} cations introduce a methanol-coupling pathway unavailable on catalysts without Cs{sup +} promoter, leading to higher alcohol synthesis rates. After ethanol formation, additional chain growth occurs via aldol-type coupling pathways using C{sub 1} intermediates derived from {sup 12}CH{sub 3}OH on both K-Cu{sub 0.5}Mg{sub 5}CeO{sub x} and Cs-Cu/ZnO/Al{sub 2}O{sub 3} catalysts.

Xu, M.; Iglesia, E.

1999-11-15

404

Minimizing fouling at hydrogenated conical-tip carbon electrodes during dopamine detection in vivo.  

PubMed

In this paper, physically small conical-tip carbon electrodes (?2-5 ?m diameter and ?4 ?m axial length) were hydrogenated to develop a probe capable of withstanding fouling during dopamine detection in vivo. Upon hydrogenation, the resultant hydrophobic sp(3) carbon surface deters adsorption of amphiphilic lipids, proteins, and peptides present in extracellular fluid and hence minimizes electrode fouling. These hydrogenated carbon electrodes showed a 35% decrease in sensitivity but little change in the limit of detection for dopamine over a 7-day incubation in a synthetic laboratory solution containing 1.0% (v/v) caproic acid (a lipid), 0.1% (w/v) bovine serum albumin and 0.01% (w/v) cytochrome C (both are proteins), and 0.002% (w/v) human fibrinopeptide B (a peptide). Subsequently, during dopamine detection in vivo, over 70% of the dopamine oxidation current remained after the first 30 min of a 60-min experiment, and at least 50% remained over the next half-period at the hydrogenated carbon electrodes. On the basis of these results, an initial average electrode surface fouling rate of 1.2% min(-1) was estimated, which gradually declined to 0.7% min(-1). These results support minimal fouling at hydrogenated carbon electrodes applied to dopamine detection in vivo. PMID:24490962

Chandra, Shaneel; Miller, Anthony D; Bendavid, Avi; Martin, Philip J; Wong, Danny K Y

2014-03-01

405

Selective Catalytic Oxidation of Hydrogen Sulfide on Activated Carbons Impregnated with Sodium Hydroxide  

SciTech Connect

Two activated carbons of different origin were impregnated with the solution of sodium hydroxide (NaOH) of various concentrations up to 10 wt %, and the effect of impregnation on the catalytic performance of the carbons was evaluated. The catalytic activity was analyzed in terms of the capacity of carbons for hydrogen sulfide (H2S) conversion and removal from hydrogen-rich fuel streams and the emission times of H2S and the products of its oxidation [e.g., sulfur dioxide (SO2) and carbonyl sulfide (COS)]. The results of impregnation showed a significant improvement in the catalytic activity of both carbons proportional to the amount of NaOH introduced. NaOH introduces hydroxyl groups (OH-) on the surface of the activated carbon that increase its surface reactivity and its interaction with sulfur-containing compounds.

Schwartz, Viviane [ORNL; Baskova, Svetlana [ORNL; Armstrong, Timothy R. [ORNL

2009-01-01

406

New clean fuel from coal -- Direct dimethyl ether synthesis from hydrogen and carbon monoxide  

SciTech Connect

Dimethyl ether (DME), which has similar physical properties to propane and is easily liquefied at low pressure, has a significant possibility as a clean and non-toxic fuel from coal or coal bed methane. Equilibrium calculation also shows a big advantage of high carbon monoxide conversion of DME synthesis compared to methanol synthesis. By using a 50 kg/day DME bench scale test plant, direct synthesis of DME from hydrogen and carbon monoxide has been studied with newly developed catalysts which are very fine particles. This test plant features a high pressure three-phase slurry reactor and low temperature DME separator. DME is synthesized at temperatures around 533--553 K and at pressures around 3--5 MPa. According to the reaction stoichiometry, the same amount of hydrogen and carbon monoxide react to DME and carbon dioxide. Carbon conversion to DME is one third and the rest of carbon is converted to carbon dioxide. As a result of the experiments, make-up CO conversion is 35--50% on an once-through basis, which is extremely high compared to that of methanol synthesis from hydrogen and carbon monoxide. DME selectivity is around 60 c-mol %. Most of the by-product is CO{sub 2} with a small amount of methanol and water. No heavy by-products have been recognized. Effluent from the reactor is finally cooled to 233--253 K in a DME separator and liquid DME is recovered as a product.

Ogawa, T.; Ono, M.; Mizuguchi, M.; Tomura, K.; Shikada, T.; Ohono, Y. [NKK Corp., Tokyo (Japan); Fujimoto, K. [Univ. of Tokyo (Japan)

1997-12-31

407

Asymmetric catalytic hydrogenation reactions in supercritical carbon dioxide  

SciTech Connect

We demonstrate that asymmetric catalytic hydrogenation reactions can be conducted in supercritical CO{sub 2} and that, in some cases, higher enantioselectivities can be achieved in this solvent relative to conventional solvents. These preliminary studies effectively demonstrate the feasibility of conducting highly enantioselective hydrogenation reactions in supercritical CO{sub 2}. Importantly, we have shown that higher enantioselectivities may be achieved in supercritical CO{sub 2} relative to conventional solvents. 16 refs., 2 tabs.

Burk, M.J.; Gross, M.F. [Duke Univ., Durham, NC (United States); Feng, S.; Tumas, W. [Los Alamos National Lab., NM (United States)

1995-08-09

408

The evolution of the structure and mechanical properties of fullerenelike hydrogenated amorphous carbon films upon annealing  

SciTech Connect

Hydrogenated amorphous carbon films were deposited on Si (100) substrates using dc-pulse plasma chemical vapor deposition. Structurally, the as-deposited carbon films could be considered as nanocomposite thin films with fullerenelike microstructure in diamondlike carbon matrix based on our previous result [Q. Wang et al., Appl. Phys. Lett. 91, 141902 (2007)]. In this paper, the evolution of the structure and the mechanical properties of hydrogenated carbon films with fullerenelike microstructure on the annealing in vacuum was investigated. The fullerenelike hydrogenated carbon films annealed at 500 deg. C showed higher hardness (16.9% harder) and higher elastic recovery (11.2% higher) than the as-deposited films. The friction coefficient of fullerenelike hydrogenated carbon films in air with 40% relative humidity remained constant at about 0.037 when annealed at 600 deg. C. The wear rate of the films decreased sharply when annealed at 200 or 300 deg. C. Structural analysis shows that annealing at 300 deg. C improved tribological properties originated from the volume increase in the fullerenelike microstructure, and further annealing at 600 deg. C improved mechanical properties originated from the transformation of nanosized curved sp{sup 2} to sp{sup 3} clusters.

Wang Qi [Department of Physics, Lanzhou University, Lanzhou 730000 (China); State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); He Deyan [Department of Physics, Lanzhou University, Lanzhou 730000 (China); Wang Chengbing; Wang Zhou; Zhang Junyan [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

2008-08-15

409

Hydrogen-bond acidic functionalized carbon nanotubes (CNTs) with covalently-bound hexafluoroisopropanol groups  

SciTech Connect

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.

Fifield, Leonard S.; Grate, Jay W.

2010-06-01

410

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 Technical Reports Server (NTRS)

Stable hydrogen, carbon, and nitrogen isotopic ratios (oD, 013C, and olSN) of organic compounds can revcal 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: CM1I2 Allan Hills (ALH) 83100, CM2 Murchison, CM2 Lewis Cliff (LEW) 90500, CM2 Lonewolf Nunataks (LON) 94101, CRZ Graves Nunataks (GRA) 95229, CRZ 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 ODC and increasing oD with increasing carbon number in the aH, (l-NH2 amino acids that correspond to predictions made for formation via Streckercyanohydrin synthesis. We also observe light ODC 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-ro-amino acids). Higher deuterium enrichments are observed in amethyl 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 CM chondrites, reflecting different parent-body chemistry.

Elsila, Jamie E.; Charnley, Steven B.; Burton, Aaron S.; Glavin, Daniel P.; Dworkin, Jason P.

2012-01-01

411

Dissociation of CH4 by electron impact: Production of metastable hydrogen and carbon fragments  

NASA Technical Reports Server (NTRS)

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.

Finn, T. G.; Carnahan, B. L.; Zipf, E. C.

1974-01-01

412

Dynamic and Thermodynamic Behavior of Carboneous and Hydrogen-Bonding Materials  

SciTech Connect

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.

Ree, F.H.; Galli, G.; Glosli, J.N.; Gygi, F.; Schwegler, E.; Viecelli, J.A.; Winter, N.W.

2000-02-04

413

X-Ray Attenuation Coefficients from 13 to 80 Mev for Hydrogen, Carbon, Water, and Aluminum  

Microsoft Academic Search

The x-ray attenuation coefficients for hydrogen, carbon, water, and aluminum have been measured in the energy range from 13 to 80 Mev by placing varying lengths of attenuators in a 90-Mev bremsstrahlung beam in a good geometry experiment using a large sodium-iodide total-absorption spectrometer as the detector. In the hydrogen case, a difference method employing cyclohexane (C6H12) and graphite was

J. M. Wyckoff; H. W. Koch

1960-01-01

414

Use of carbon nanostructures for hydrogen storage for environmentally safe automotive applications  

Microsoft Academic Search

Carbon nanostructures are considered materials with a high potential for hydrogen storage. CCVD technique was used to grown nanotubes with diameters ranging from 50 to 100 nm on a Ni:Cu catalyst and nanofibers with diameters ranging from 10 to 100 nm on a Pd\\/La2O3 catalyst. The hydrogen uptake experiments performed volumetrically in a Sievert-type installation, showed the quantity of desorbed

A. S. Biris; A. R. Biris; D. Lupu; D. Buzatu; J. Darsey; M. K. Muzumder

2004-01-01

415

Relation of Hydrogen and Methane to Carbon Monoxide in Exhaust Gases from Internal-Combustion Engines  

NASA Technical Reports Server (NTRS)

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.

Gerrish, Harold C; Tessmann, Arthur M

1935-01-01

416

Hydrogenolysis of 5-carbon sugars, sugar alcohols, and other methods and compositions for reactions involving hydrogen  

DOEpatents

Methods and compositions for reactions of hydrogen over a Re-containing catalyst with compositions containing a 5-carbon sugar, sugar alcohol, or lactic acid are described. It has been surprisingly discovered that reaction with hydrogen over a Re-containing multimetallic catalyst resulted in superior conversion and selectivity to desired products such as propylene glycol. A process for the synthesis of PG from lactate or lactic acid is also described.

Werpy, Todd A [West Richland, WA; Zacher, Alan H [Kennewick, WA

2002-11-12

417

Hydrogenolysis Of 5-Carbon Sugars, Sugar Alcohols And Compositions For Reactions Involving Hydrogen  

DOEpatents

Methods and compositions for reactions of hydrogen over a Re-containing catalyst with compositions containing a 5-carbon sugar, sugar alcohol, or lactic acid are described. It has been surprisingly discovered that reaction with hydrogen over a Re-containing multimetallic catalyst resulted in superior conversion and selectivity to desired products such as propylene glycol. A process for the synthesis of PG from lactate or lactic acid is also described.

Werpy, Todd A. (West Richland, WA); Frye, Jr., John G. (Richland, WA); Zacher, Alan H. (Kennewick, WA); Miller, Dennis J. (Okemos, MI)

2004-01-13

418

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

Microsoft Academic Search

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

BARBARA MORASCH; HANS H. RICHNOW; BERNHARD SCHINK; RAINER U. MECKENSTOCK

2001-01-01

419

Enhanced hydrogen production from biomass with in situ carbon dioxide capture using calcium oxide sorbents  

Microsoft Academic Search

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

Nicholas H. Florin; Andrew T. Harris

2008-01-01

420

Deposition and characterization of diamond-like carbon films with and without hydrogen and nitrogen  

NASA Astrophysics Data System (ADS)

Thin, non-hydrogenated, hydrogenated and nitrogenated amorphous carbon films were deposited on glassy carbon, silicon and quartz using unbalanced magnetron (UBM) sputtering of a graphite target under biased and grounded condition. Argon, argon+nitrogen and nitrogen were used as sputtering gases. The effect of hydrogenation, nitrogenation and negative and positive bias on the final concentration of trapped elements, optical band gap and molecular bonding has been studied. No profound effect of bias on the elemental conectrations of trapped elements have been found except for argon whose trapping is found to increase with bias. Hydrogenation resulted in films that enabled argon to detrap from the films. Increased nitrogen contents were observed for the films deposited by nitrogen sputtering of graphite target as opposed to the nitrogen contents found in the case of argon+nitrogen sputtering. An increase in the optical gaps of the films were observed on hydrogenation however with nitrogenation there was a trend of decreasing optical gaps with an increase in the disorder, as determined by the measurement of the Urbach tail width. An increase in sp3 bonding was observed with the increased hydrogen content in DLC films. Carbon-nitrogen films presented a very complex molecular bonding structure that needs further investigation.

Kayani, Asghar N.

421

Synthesis of superlow friction carbon films from highly hydrogenated methane plasmas.  

SciTech Connect

In this study, we investigated the friction and wear performance of diamondlike carbon films (DLC) derived from increasingly hydrogenated methane plasmas. The films were deposited on steel substrates by a plasma-enhanced chemical vapor deposition process at room temperature and the tribological tests were performed in dry nitrogen. Tests results revealed a close correlation between the hydrogen in source gas plasma and the friction and wear coefficients of the DLC films. Specifically, films grown in plasmas with higher hydrogen-to-carbon ratios had much lower friction coefficients and wear rates than did films derived from source gases with lower hydrogen-to-carbon ratios. The lowest friction coefficient (0.003) was achieved with a film derived from 25% methane--75% hydrogen, while a coefficient of 0.015 was found for films derived from pure methane. Similar correlations were observed for wear rates. Films derived from hydrogen-rich plasmas had the least wear, while films derived from pure methane suffered the highest wear. We used a combination of surface analytical methods to characterize the structure and chemistry of the DLC films and worn surfaces.

Erdemir, A.; Eryilmaz, O. L.; Nilufer, I. B.; Fenske, G. R.

2000-10-13

422

Optimizing the Binding Energy of Hydrogen on Nanostructured Carbon Materials through Structure Control and Chemical Doping  

SciTech Connect

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.

Jie Liu

2011-02-01

423

Carbon and hydrogen isotope fractionation by moderately thermophilic methanogens1  

Microsoft Academic Search

is enriched in 13C when compared with other natural sources of methane; the magnitude of this isotope effect raises the possibility that methane produced at elevated temperature by the aceticlastic reaction could be mistaken for thermogenic methane based on carbon isotopic content. Studies of H2\\/CO2 methanogenesis were conducted with Methanothermobacter marburgensis . The fractionation of carbon isotopes between CO2 and

David L. Valentine; Amnat Chidthaisong; Andrew Rice; William S. Reeburgh; Stanley C. Tyler

2004-01-01

424

In situ diagnostic for monitoring of deuterium and tritium in re-deposited carbon layers by laser induced desorption  

NASA Astrophysics Data System (ADS)

Tritium retention in the plasma facing components and co-deposition in re-deposited layers is a key issue for ITER, since the operation of the machine will be restricted to a maximum inventory of tritium. Development of methods to detect in real time the amount of retained fuel in the in vessel components is urgently required. A promising method for this is the pulsed laser induced desorption, by which the imbedded gas in such layers is released into the plasma where the injected atoms and molecules are excited and ionised and the characteristic line emission is detected spectroscopically. In this paper the release process is investigated in detail for amorphous hydrocarbon layers in a laboratory experiment, as a prerequisite for the later application and determination of conversion factors between line radiation and desorbed flux in TEXTOR plasmas. A Nd:YAG laser has been used with nearly constant output power leading to a smooth controllable increase of layer temperature, resulting in a complete desorption of D 2 and CD 4 as well as preventing carbon sublimation.

Schweer, B.; Irrek, F.; Sergienko, G.; Philipps, V.; Samm, U.

2007-06-01

425

Stable hydrogen and carbon isotope ratios of extractable hydrocarbons in the Murchison meteorite  

NASA Technical Reports Server (NTRS)

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.

Krishnamurthy, R. V.; Epstein, S.; Pizzarello, S.; Cronin, J. R.; Yuen, G. U.

1991-01-01

426

Efficient and durable hydrogen evolution electrocatalyst based on nonmetallic nitrogen doped hexagonal carbon  

PubMed Central

The feasibility of renewable energy technology, hydrogen production by water electrolysis, depends on the design of efficient and durable electrocatalyst composed of earth-abundant elements. Herein, a highly active and stable nonmetallic electrocatalyst, nitrogen doped hexagonal carbon (NHC), was developed for hydrogen production. It exhibited high activity for hydrogen evolution with a low overpotential of only 65?mV, an apparent exchange current density of 5.7 × 10?2?mA cm?2 and a high hydrogen production rate of 20.8?mL cm?2 h?1 at ?0.35?V. The superior hydrogen evolution activity of NHC stemmed from the intrinsic electrocatalytic property of hexagonal nanodiamond, the rapid charge transfer and abundance of electrocatalytic sites after nitrogen doping. Moreover, NHC was stable in a corrosive acidic solution during electrolysis under high current density. PMID:25354806

Liu, Yanming; Yu, Hongtao; Quan, Xie; Chen, Shuo; Zhao, Huimin; Zhang, Yaobin

2014-01-01

427

LITERATURE SURVEY OF GASEOUS HYDROGEN EFFECTS ON THE MECHANICAL PROPERTIES OF CARBON AND LOW ALLOY STEELS  

SciTech Connect

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).

Lam, P; Robert Sindelar, R; Thad Adams, T

2007-04-18

428

LITERATURE SURVEY OF GASEOUS HYDROGEN EFFECTS ON THE MECHANICAL PROPERTIES OF CARBON AND LOW ALLOY STEELS  

SciTech Connect

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).

Lam, P; Andrew Duncan, A; Robert Sindelar, R; Thad Adams, T

2009-04-27

429

Efficient and durable hydrogen evolution electrocatalyst based on nonmetallic nitrogen doped hexagonal carbon  

NASA Astrophysics Data System (ADS)

The feasibility of renewable energy technology, hydrogen production by water electrolysis, depends on the design of efficient and durable electrocatalyst composed of earth-abundant elements. Herein, a highly active and stable nonmetallic electrocatalyst, nitrogen doped hexagonal carbon (NHC), was developed for hydrogen production. It exhibited high activity for hydrogen evolution with a low overpotential of only 65 mV, an apparent exchange current density of 5.7 × 10-2 mA cm-2 and a high hydrogen production rate of 20.8 mL cm-2 h-1 at -0.35 V. The superior hydrogen evolution activity of NHC stemmed from the intrinsic electrocatalytic property of hexagonal nanodiamond, the rapid charge transfer and abundance of electrocatalytic sites after nitrogen doping. Moreover, NHC was stable in a corrosive acidic solution during electrolysis under high current density.

Liu, Yanming; Yu, Hongtao; Quan, Xie; Chen, Shuo; Zhao, Huimin; Zhang, Yaobin

2014-10-01

430

New Pathways and Metrics for Enhanced, Reversible Hydrogen Storage in Boron-Doped Carbon Nanospaces  

SciTech Connect

This project, since its start in 2007—entitled “Networks of boron-doped carbon nanopores for low-pressure reversible hydrogen storage” (2007-10) and “New pathways and metrics for enhanced, reversible hydrogen storage in boron-doped carbon nanospaces” (2010-13)—is in support of the DOE's National Hydrogen Storage Project, as part of the DOE Hydrogen and Fuel Cells Program’s comprehensive efforts to enable the widespread commercialization of hydrogen and fuel cell technologies in diverse sectors of the economy. Hydrogen storage is widely recognized as a critical enabling technology for the successful commercialization and market acceptance of hydrogen powered vehicles. Storing sufficient hydrogen on board a wide range of vehicle platforms, at energy densities comparable to gasoline, without compromising passenger or cargo space, remains an outstanding technical challenge. Of the main three thrust areas in 2007—metal hydrides, chemical hydrogen storage, and sorption-based hydrogen storage—sorption-based storage, i.e., storage of molecular hydrogen by adsorption on high-surface-area materials (carbons, metal-organic frameworks, and other porous organic networks), has emerged as the most promising path toward achieving the 2017 DOE storage targets of 0.055 kg H2/kg system (“5.5 wt%”) and 0.040 kg H2/liter system. The objective of the project is to develop high-surface-area carbon materials that are boron-doped by incorporation of boron into the carbon lattice at the outset, i.e., during the synthesis of the material. The rationale for boron-doping is the prediction that boron atoms in carbon will raise the binding energy of hydro- gen from 4-5 kJ/mol on the undoped surface to 10-14 kJ/mol on a doped surface, and accordingly the hydro- gen storage capacity of the material. The mechanism for the increase in binding energy is electron donation from H2 to electron-deficient B atoms, in the form of sp2 boron-carbon bonds. Our team is proud to have demonstrated the predicted increase in binding energy experimentally, currently at ~10 kJ/mol. The synthetic route for incorporation of boron at the outset is to create appropriately designed copoly- mers, with a boron-free and a boron-carrying monomer, followed by pyrolysis of the polymer, yielding a bo- ron-substituted carbon scaffold in which boron atoms are bonded to carbon atoms by synthesis. This is in contrast to a second route (funded by DE-FG36-08GO18142) in which first high-surface area carbon is cre- ated and doped by surface vapor deposition of boron, with incorporation of the boron into the lattice the final step of the fabrication. The challenge in the first route is to create high surface areas without compromising sp2 boron-carbon bonds. The challenge in the second route is to create sp2 boron-carbon bonds without com- promising high surface areas.

Pfeifer, Peter [University of Missouri; Wexler, Carlos [University of Missouri; Hawthorne, M. Frederick [University of Missouri; Lee, Mark W. [University of Missouri; Jalistegi, Satish S. [University of Missouri

2014-08-14

431

Unmodified versus caustics-impregnated carbons for control of hydrogen sulfide emissions from sewage treatment plants  

SciTech Connect

Unmodified and caustic-impregnated carbons were compared as adsorbents for hydrogen sulfide in the North River Water Pollution Control Plant in New York City over a period of 2 years. The carbons were characterized using accelerated H{sub 2}S breakthrough capacity tests, sorption of nitrogen, potentiometric titration, and thermal analysis. The accelerated laboratory tests indicate that the initial capacity of caustic-impregnated carbons exceeds that of unmodified carbon, but the nature of real-life challenge streams, particularly their lower H{sub 2}S concentrations, nullifies this advantage. As the caustic content of the impregnated carbon is consumed, the situation reverses, and the unmodified carbon becomes more effective. When the concentration of H{sub 2}S is low, the developed surface area and pore volume along with the affinity to retain water create a favorable environment for dissociative adsorption of hydrogen sulfide and its oxidation to elemental sulfur, S{sup 4+}, and S{sup 6+}. In the case of the caustic carbon, the catalytic impact of the carbon surface is limited, and its good performance lasts only while active base is present. The results also show the significant differences in performance of unmodified carbons due to combined effects of their porosity and surface chemistry.

Bandosz, T.J.; Bagreev, A.; Adib, F.; Turk, A.

2000-03-15

432

Renewable Hydrogen Carrier Carbohydrate: Constructing the Carbon-Neutral Carbohydrate Economy  

SciTech Connect

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.

Zhang, Y.-H. Percival [Virginia Polytechnic Institute and State University (Virginia Tech); Mielenz, Jonathan R [ORNL

2011-01-01

433

N-doped carbon networks: alternative materials tracing new routes for activating molecular hydrogen.  

PubMed

The fragmentation of molecular hydrogen on N-doped carbon networks was investigated by using molecular (polyaromatic macrocycles) as well as truncated and periodic (carbon nanotubes) models. The computational study was focused on the ergonicity analysis of the reaction and on the properties of the transition states involved when constellations of three or four pyridinic nitrogen atom defects are present in the carbon network. Calculations show that whenever N-defects are embedded in species characterized by large conjugated ?-systems, either in polyaromatic macrocycles or carbon nanotubes, the corresponding H2 bond cleavage is largely exergonic. The fragmentation Gibbs free energy is affected by the final arrangement of the hydrogen atoms on the defect and by the extension of the ?-electron cloud, but it is not influenced by the curvature of the system. PMID:25614208

Cortese, Remedios; Ferrante, Francesco; Roggan, Stefan; Duca, Dario

2015-02-23

434

Ultrananopores in Carbons by Boron-neutron Capture and Their Effect on Hydrogen Storage  

NASA Astrophysics Data System (ADS)

The Alliance for Collaborative Research in Alternative Fuel Technology (ALL-CRAFT) has been optimizing high surface area activated carbon nanospaces for high capacity hydrogen storage. Boron doped samples have been prepared by vapor deposition of decaborane. Neutron irradiation of Boron doped activated carbon was done at the University of Missouri Research Reactor (MURR). Ultrananopores created by alpha particle fission tracks from Boron-neutron capture alter the surface and the adsorption properties of activated Carbons. A detailed theoretical model of the creation and the structure of defects on graphene sheets was developed. BET surface areas, porosity, and pores size distributions of modified activated carbons were measured using sub-critical nitrogen isotherms. Hydrogen adsorption isotherms of irradiated samples were indicative of record fraction of high binding energies and record fraction of sub-nm pores compared to their unirradiated parent samples.

Romanos, J.; Robertson, D.; Beckner, M.; Kraus, M.; Kuchta, B.; Firlej, L.; Pfeifer, P.

2010-03-01

435

Migration Mechanism for Atomic Hydrogen in Porous Carbon Materials  

SciTech Connect

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 th